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Energy balance is maintained by controlling both energy intake and energy expenditure. Thyroid hormones play a crucial role in regulating energy expenditure. Their levels are adjusted by a tight feed back-control led regulation of thyroid hormone production/incretion and by their hepatic metabolism. Thyroid hormone degradation has previously been shown to be enhanced by treatment with phenobarbital or other antiepileptic drugs due to a CAR-dependent induction of phase 11 enzymes of xenobiotic metabolism. We have recently shown, that PPAR alpha agonists synergize with phenobarbital to induce another prototypical CAR target gene, CYP2B1. Therefore, it was tested whether a PPAR alpha agonist could enhance the phenobarbital-dependent acceleration of thyroid hormone elimination. In primary cultures of rat hepatocytes the apparent half-life of T3 was reduced after induction with a combination of phenobarbital and the PPARa agonist WY14643 to a larger extent than after induction with either Compound alone. The synergistic reduction of the half-life could be attributed to a synergistic induction of CAR and the CAR target genes that code for enzymes and transporters involved in the hepatic elimination of T3, such as OATP1A1, OATP1A3, UGT1A3 and UCT1A10. The PPAR alpha-dependent CAR induction and the subsequent induction of T3-eliminating enzymes might be of physiological significance for the fasting- incluced reduction in energy expenditure by fatty acids as natural PPARa ligands. The synergism of the PPAR alpha agonist WY14643 and phenobarbital in inducing thyroid hormone breakdown might serve as a paradigm for the synergistic disruption of endocrine control by other combinations of xenobiotics.
The incidence of cardiovascular diseases increases with the growth of the human population and an aging society, leading to very high expenses in the public health system. Therefore, it is challenging to develop sophisticated methods in order to improve medical diagnostics. The question whether the normal heart rate is chaotic or not is an attempt to elucidate the underlying mechanisms of cardiovascular dynamics and therefore a highly controversial topical challenge. In this contribution we demonstrate that linear and nonlinear parameters allow us to separate completely the data sets of the three groups provided for this controversial topic in nonlinear dynamics. The question whether these time series are chaotic or not cannot be answered satisfactorily without investigating the underlying mechanisms leading to them. We give an example of the dominant influence of respiration on heart beat dynamics, which shows that observed fluctuations can be mostly explained by respiratory modulations of heart rate and blood pressure (coefficient of determination: 96%). Therefore, we recommend reformulating the following initial question: "Is the normal heart rate chaotic?" We rather ask the following: " Is the normal heart rate 'chaotic' due to respiration?"
Activated carbon has become a widely used tool to investigate root-mediated allelopathy of plants, especially in plant invasion biology, because it adsorbs and thereby neutralizes root exudates. Allelopathy has been a controversially debated phenomenon for years, which revived in plant invasion biology as one possible reason for the success of invasive plants. Noxious plant exudates may harm other plants and provide an advantage to the allelopathic plant. However, root exudates are not always toxic, but may stimulate the microbial community and change nutrient availability in the rhizosphere. In a greenhouse experiment, we investigated the interacting effects of activated carbon, arbuscular mycorrhiza and plant competition between the invasive Senecio inaequidens and the native Artemisia vulgaris. Furthermore, we tested whether activated carbon showed any undesired effects by directly affecting mycorrhiza or soil chemistry. Contrary to the expectation, S. inaequidens was a weak competitor and we could not support the idea that allelopathy was involved in the competition. Activated carbon led to a considerable increase in the aboveground biomass production and reduced the infection with arbuscular mycorrhiza of both plant species. We expected that arbuscular mycorrhiza promotes plant growth by increasing nutrient availability, but we found the contrary when activated carbon was added. Chemical analyses of the substrate showed, that adding activated carbon resulted in a strong increase in plant available phosphate and in a decrease of the C-organic/N-total ration both of which suggest stimulated microbial activity. Thus, activated carbon not only reduced potential allelopathic effects, but substantially changed the chemistry of the substrate. These results show that activated carbon should be handled with great care in ecological experiments on allelopathy because of possible confounding effects on the soil community.
The effect of introducing positive charges (lysines) in human cytochrome c (cyt c) on the redox properties and reaction rates of cyt c with superoxide radicals was studied. The mutated forms of this electron-transfer protein are used as sensorial recognition elements for the amperometric detection of the reactive oxygen radical. The proteins were prepared by site-directed mutagenesis focusing on amino acids near the heme edge. The 11 mutants of human cyt c expressed in the course of this research have been characterized by UV-vis spectroscopy, circular dichroism, and NMR spectroscopy to verify overall structure integrity as well as axial coordination of the heme iron. The mutants are investigated voltammetrically using promoter-modified gold electrodes with respect to redox activity and formal redox potential. The rate constants for the reaction with superoxide have been determined spectrophotometrically. Four mutants show a higher reaction rate with the radical as compared to the wild type. These mutants are used for the construction of superoxide sensors based on thiol-modified gold electrodes and covalently fixed proteins. We found that the E66K mutant-based electrode has a clearly higher sensitivity in comparison with the wild-type-based sensor while retaining the high selectivity and showing a good storage stability.
Fault zones are the locations where motion of tectonic plates, often associated with earthquakes, is accommodated. Despite a rapid increase in the understanding of faults in the last decades, our knowledge of their geometry, petrophysical properties, and controlling processes remains incomplete. The central questions addressed here in our study of the Dead Sea Transform (DST) in the Middle East are as follows: (1) What are the structure and kinematics of a large fault zone? (2) What controls its structure and kinematics? (3) How does the DST compare to other plate boundary fault zones? The DST has accommodated a total of 105 km of left-lateral transform motion between the African and Arabian plates since early Miocene (similar to 20 Ma). The DST segment between the Dead Sea and the Red Sea, called the Arava/Araba Fault (AF), is studied here using a multidisciplinary and multiscale approach from the mu m to the plate tectonic scale. We observe that under the DST a narrow, subvertical zone cuts through crust and lithosphere. First, from west to east the crustal thickness increases smoothly from 26 to 39 km, and a subhorizontal lower crustal reflector is detected east of the AF. Second, several faults exist in the upper crust in a 40 km wide zone centered on the AF, but none have kilometer-size zones of decreased seismic velocities or zones of high electrical conductivities in the upper crust expected for large damage zones. Third, the AF is the main branch of the DST system, even though it has accommodated only a part (up to 60 km) of the overall 105 km of sinistral plate motion. Fourth, the AF acts as a barrier to fluids to a depth of 4 km, and the lithology changes abruptly across it. Fifth, in the top few hundred meters of the AF a locally transpressional regime is observed in a 100-300 m wide zone of deformed and displaced material, bordered by subparallel faults forming a positive flower structure. Other segments of the AF have a transtensional character with small pull-aparts along them. The damage zones of the individual faults are only 5-20 m wide at this depth range. Sixth, two areas on the AF show mesoscale to microscale faulting and veining in limestone sequences with faulting depths between 2 and 5 km. Seventh, fluids in the AF are carried downward into the fault zone. Only a minor fraction of fluids is derived from ascending hydrothermal fluids. However, we found that on the kilometer scale the AF does not act as an important fluid conduit. Most of these findings are corroborated using thermomechanical modeling where shear deformation in the upper crust is localized in one or two major faults; at larger depth, shear deformation occurs in a 20-40 km wide zone with a mechanically weak decoupling zone extending subvertically through the entire lithosphere.
Point-of-care testing (POCT) is a fast developing area in clinical diagnostics that is considered to be one of the main driving forces for the future in vitro diagnostic market. POCT means decentralized testing at the site of patient care. The most important POCT devices are handheld blood glucose sensors. In some of these sensors, after the application of less than 1 A mu l whole blood, the results are displayed in less than 10 s. For protein determination, the most commonly used devices are based on lateral flow technology. Although these devices are convenient to use, the results are often only qualitative or semiquantitative. The review will illuminate some of the current methods employed in POCT for proteins and will discuss the outlook for techniques (e.g., electrochemical immunosensors) that could have a great impact on future POCT of proteins.
Prävention kindlichen übergewichts : elterliche Selbstwirksamkeit und Handlungsergebniserwartungen
(2009)
Adipositas ist ein ernstzunehmendes gesundheitliches Problem, welches das physische und psychosoziale Wohlbefinden von Kindern und deren Eltern beeintraechtigt und somit wirksamer praeventiver Ansaetze bedarf. Dabei ist es bedeutsam, welche Barrieren, Anreize und Selbstwirksamkeitserwartungen Eltern fuer oder gegen die Teilnahme an solchen Programmen entscheiden lassen. Ziel der Studie war es zu untersuchen, wie Muetter ihre Selbstwirksamkeits- und Handlungsergebniserwartungen beschreiben und inwieweit sich soziodemografische Aspekte auf diese Einschaetzungen auswirken. Insgesamt wurden 219 Muetter von Kindern im Alter von 3-6 Jahren befragt. Mehr als die Haelfte der befragten Muetter waren uebergewichtig bzw. adipoes sowie 12% der Kinder. Es ergaben sich weder fuer das Alter und das Geschlecht des Kindes noch fuer das Familieneinkommen Unterschiede in den Handlungsergebniserwartungen. Muetter mit geringerer Bildung nahmen weniger Anreize wahr und Muetter mit uebergewichtigen Kindern sahen weniger Barrieren fuer eine Programmteilnahme. uebergewichtige Muetter dagegen bewerteten die Barrieren und Anreize hoeher als normalgewichtige Muetter. Hinsichtlich der Selbstwirksamkeit ergaben sich ebenfalls Unterschiede bezueglich der Bildung und des Gewichts der Mutter sowie des Kindes. Im Vorfeld einer Intervention sollte ein Beratungsgespraech bezogen auf die muetterlichen Erwartungen stattfinden, um die Teilnahmebereitschaft und den Programmerfolg zu unterstuetzen.
OBJECTIVE: To examine factors associated with the maternal perception of the weight status in related and unrelated children and to examine whether associated health risks for children's physical and mental health are recognized. PATIENTS AND METHODS: Two hundred nineteen mothers with children between 3 and 6 years of age took part in this study. The participating mothers were recruited from inpatient clinics and kindergartens. Parents were presented with 9 silhouettes representing different age- and gender-specific BMI percentiles. Demographic and weight-related variables were assessed with regard to their influence on the accuracy of the maternal weight estimation in general and for their own child. RESULTS: Of the participating mothers, 64.5% identified the overweight silhouettes of preschool- aged children correctly. However, only 48.8% of the mothers identified the overweight silhouettes associated with an increased risk for physical health problems, and 38.7% identified the silhouettes associated with an increased mental health risk. Mothers with a lower educational background were more likely to misclassify the overweight silhouettes and underestimate the associated health problems. For their own child, only 40.3% of the mothers chose silhouettes that were in agreement with the objective weight status of their child. This underestimation was associated with a higher maternal and child weight status but not with a general inability to identify the weight status of children. CONCLUSIONS: Identifying unrelated overweight silhouettes is influenced by maternal education level, whereas estimating their own child's weight status is influenced by the weight status of the mother and the child. Hence, feedback on the child's risk to become overweight is necessary to increase maternal risk awareness and willingness to take part in prevention programs.
Two well known phenomena associated with erupting filaments are the transient coronal holes that form on each side of the filament channel and the bright post-event arcade with its expanding double row of footpoints. Here we focus on a frequently overlooked signature of filament eruptions: the spike- or fan-shaped brightenings that appear to mark the far endpoints of the filament. From a sample of non-active-region filament events observed with the Extreme- Ultraviolet Imaging Telescope on the Solar and Heliospheric Observatory, we find that these brightenings usually occur near the outer edges of the transient holes, in contrast to the post-event arcades, which define their inner edges. The endpoints are often multiple and are rooted in and around strong network flux well outside the filament channel, a result that is consistent with the axial field of the filament being much stronger than the photospheric field inside the channel. The extreme ultraviolet brightenings, which are most intense at the time of maximum outward acceleration of the filament, can be used to determine unambiguously the direction of the axial field component from longitudinal magnetograms. Their location near the outer boundary of the transient holes suggests that we are observing the footprints of the current sheet formed at the leading edge of the erupting filament, as distinct from the vertical current sheet behind the filament which is the source of the post-event arcade.
The transmembrane tight junction protein occludin is sensitive to oxidative stress. Occludin oligomerizes; however, its function in the tight junction is unknown. The cytosolic C-terminal tail contains a coiled coil-domain and forms dimers contributing to the oligomerization. The regulation of the oligomerization remains unclear. As the domain area contains sulfhydryl residues, we tested the hypothesis that the dimerization of the coiled coil-domain depends on these residues. We showed that the dimerization is modulated by the thiol concentration in the low-millimolar range, which is relevant both for physiological and pathophysiological conditions. Masking the sulfhydryl residues in the fragment by covalent binding of 4-vinyl pyridine prevented the dimerization but did not affect its helical structure and cylindric shape. The data demonstrate, for the first time, that disulfide bridge formation of murine cystein 408 is involved in the dimerization. This process is redox-sensitive but the secondary structure of the domain is not. It is concluded that the dimerization of occludin may play a regulatory role in the tight junction assembly under physiological and pathological conditions.
Occludin is a self-associating transmembrane tight junction protein affected in oxidative stress. However, its function is unknown. The cytosolic C-terminal tail contains a coiled coil-domain forming dimers contributing to the self- association. Studying the hypothesis that the self-association is redox-sensitive, we found that the dimerization of the domain depended on the sulfhydryl concentration of the environment in low-millimolar range. Under physiological conditions, monomers and dimers were detected. Masking the sulfhydryl residues in the domain prevented the dimerization but affected neither its helical structure nor cylindric shape. Incubation of cell extracts containing full-length occludin with sulfhydryl reagents prevented the dimerization; a cysteine/alanine exchange mutant also did not show dimer formation. This demonstrates, for the first time, that disulfide bridge formation of the domain is involved in the occludin dimerization. It is concluded that the redox-dependent dimerization of occludin may play a regulatory role in the tight junction assembly under physiological and pathological conditions.
Background: Speech development is frequently impaired in very low birth weight (VLBW) infants. Few and controversial data have been published on concepts regarding the influence of bilingual education. Aims: The objectives of the current study were to assess the influence of parental bilingualism on speech development and neurodevelopmental outcome in low risk VLBW infants. Study design: Monocentric prospective controlled cohort study with standardized follow- up. Subjects: We recruited 50 singleton VLBW infants each from monolingual and bilingual families as well as 90 term control infants. The infants were free of disease and congenital malformation. Outcome measures: Griffiths scales of infant development at the corrected ages of 6 and 12 months, Bayley Scales of Infant Development II (BSID II) with 22 months. Results: In general, both bilingual and monolingual VLBW infants achieved age-specific milestones at the corrected age of 6,12 and 22 months. However, bilingual VLBW infants achieved significantly lower scores than their monolingual peers in all cognitive subscales. The influence of maternal education on the neurodevelopmental outcome of the preterm infants was not significant; the subscales' correlation with socioeconomic or biological parameters was poor. However, a clear differentiation between social status and bilingual environment importance for speech development was not possible. Conclusions: In the setting of the present investigation, parental bilingualism is associated with slower neurodevelopment in VLBW infants during the first 2 years of life.
Carbon assimilation mode in mixotrophs and the fatty acid composition of their rotifer consumers
(2009)
P>1. We examined an important ecophysiological link between the mixotrophic flagellate Chlamydomonas acidophila and its consumers, the rotifers Elosa worallii, Cephalodella sp. and Brachionus sericus, by comparing their fatty acid profiles. 2. The mixotrophic flagellate was grown under either exclusively autotrophic conditions in the light, under exclusively heterotrophic conditions in the dark with an organic carbon source (glucose), or in the light plus the organic carbon sources (=mixotrophic). 3. Under heterotrophic growth conditions, C. acidophila strongly reduced its content of the n-3 polyunsaturated fatty acid (PUFA) alpha-linolenic acid (ALA, C18:3n-3) compared with auto- and mixotrophic growth conditions. Although PUFAs with more than 18 carbon atoms were not detected in C. acidophila, significant amounts of eicosatetraenoic (ETA, 20:4n-3) and eicosapentaenoic acid (EPA, 20:5n-3) were found in three rotifer consumers. 4. Species-specific differences in the fatty acid profiles with respect to ETA, EPA and the precursor ALA were found in the rotifers: Brachionus and Cephalodella fed on the heterotrophic diets synthesised less EPA. In Elosa, smaller amounts of ALA were detected but were converted efficiently to a constant content of EPA and to an exceptionally high content of ETA. 5. Since in nature the mode of carbon assimilation among mixotrophic organisms differs, and their fatty acid composition varies depending on their mode of carbon assimilation, the availability of ALA might be critical for their consumers. An insufficient dietary supply of this precursor for the synthesis of ETA and EPA can prevent consumers from regulating their content of ETA and EPA. Therefore, observed differences in values of the latter might underly species-specific differences in the competitive capability of consumers.
Secretion in blowfly (Calliphora vicina) salivary glands is regulated by the neurohormone serotonin (5-HT), which activates the InsP(3)/Ca2+ pathway and the cAMP/protein kinase A (PKA) pathway in the secretory cells. The latter signaling cascade induces the activation of a vacuolar H+-ATPase on the apical membrane. Here, we have determined the distribution of PKA by using antibodies against the PKA regulatory subunit-II (PKA-RII) and the PKA catalytic subunit (PKA-C) of Drosophila. PKA is present in high concentrations within the secretory cells. PKA-RII and PKA-C co-distribute in non-stimulated glands, being enriched in the basal portion of the secretory cells. Exposure to 8-CPT-cAMP or 5-HT induces the translocation of PKA-C to the apical membrane, whereas the PKA-RII distribution remains unchanged. The recruitment of PKA-C to the apical membrane corroborates our hypothesis that vacuolar H+-ATPase, which is enriched in this membrane domain, is a target protein for PKA.
Peripheral T-cell (TC) tolerance can be induced by tolerogenic antigen-presenting cell (APC). A prerequisite is the reduction or blockade of B7 of APC. Besides dendritic cell, B cells can be used as APC. Here, we show the generation B cells with reduced B7 expression by lentiviral transduction of endoplasmic reticulum (ER)-directed CTLA4. Vectors coding for the human CTL4-Ig were used for the human B-cell line Raji. Transduction efficiency was over 90% (MOI = 3). For the murine B-cell line A20 and for primary mouse B cells, murine CTLA4 was used. We show that B cells with reduced B7 expression reduce the antigen (Ag) specific TC proliferation in vitro. B cells expressing an ER-directed CTLA4 may reduce Ag-specific immune responses.
This paper reports on a project to compare predictions from a range of catchment models applied to a mesoscale river basin in central Germany and to assess various ensemble predictions of catchment streamflow. The models encompass a large range in inherent complexity and input requirements. In approximate order of decreasing complexity, they are DHSVM, MIKE-SHE, TOPLATS, WASIM-ETH, SWAT, PRMS, SLURP, HBV, LASCAM and IHACRES. The models are calibrated twice using different sets of input data. The two predictions from each model are then combined by simple averaging to produce a single-model ensemble. The 10 resulting single-model ensembles are combined in various ways to produce multi-model ensemble predictions. Both the single-model ensembles and the multi-model ensembles are shown to give predictions that are generally superior to those of their respective constituent models, both during a 7-year calibration period and a 9- year validation period. This occurs despite a considerable disparity in performance of the individual models. Even the weakest of models is shown to contribute useful information to the ensembles they are part of. The best model combination methods are a trimmed mean (constructed using the central four or six predictions each day) and a weighted mean ensemble (with weights calculated from calibration performance) that places relatively large weights on the better performing models. Conditional ensembles. in which separate model weights are used in different system states (e.g. summer and winter, high and low flows) generally yield little improvement over the weighted mean ensemble. However a conditional ensemble that discriminates between rising and receding flows shows moderate improvement. An analysis of ensemble predictions shows that the best ensembles are not necessarily those containing the best individual models. Conversely, it appears that some models that predict well individually do not necessarily combine well with other models in multi-model ensembles. The reasons behind these observations may relate to the effects of the weighting schemes, non- stationarity of the climate series and possible cross-correlations between models.
External climate forcings-such as long-term changes in solar insolation-generate different climate responses in tropical and high latitude regions(1). Documenting the spatial and temporal variability of past climates is therefore critical for understanding how such forcings are translated into regional climate variability. In contrast to the data- richmiddle and high latitudes, high-quality climate-proxy records from equatorial regions are relatively few(2-4), especially from regions experiencing the bimodal seasonal rainfall distribution associated with twice-annual passage of the Intertropical Convergence Zone. Here we present a continuous and well-resolved climate-proxy record of hydrological variability during the past 25,000 years from equatorial East Africa. Our results, based on complementary evidence from seismic-reflection stratigraphy and organic biomarker molecules in the sediment record of Lake Challa near Mount Kilimanjaro, reveal that monsoon rainfall in this region varied at half-precessional (similar to 11,500-year) intervals in phase with orbitally controlled insolation forcing. The southeasterly and northeasterly monsoons that advect moisture from the western Indian Ocean were strengthened in alternation when the inter-hemispheric insolation gradient was at a maximum; dry conditions prevailed when neither monsoon was intensified and modest local March or September insolation weakened the rain season that followed. On sub-millennial timescales, the temporal pattern of hydrological change on the East African Equator bears clear high-northern-latitude signatures, but on the orbital timescale it mainly responded to low-latitude insolation forcing. Predominance of low-latitude climate processes in this monsoon region can be attributed to the low-latitude position of its continental regions of surface air flow convergence, and its relative isolation from the Atlantic Ocean, where prominent meridional overturning circulation more tightly couples low-latitude climate regimes to high-latitude boundary conditions.
The femtosecond-laser-induced, substrate-mediated associative desorption of molecular hydrogen and deuterium from a Ru(0001) surface in the so-called DIMET limit is studied theoretically. Two widely used models, a "quantum nonadiabatic" approach and a "classical adiabatic" one are employed and compared to each other. The quantum model is realized by the Monte Carlo wave packet (MCWP) method in the framework of open-system density matrix theory: The classical approach is realized with the help of (frictional) Langevin dynamics with stochastic forces. For both models the same ground-state potential energy surface is used and the same two-temperature model adopted to describe the hot- electron-driven desorption dynamics. Apart from these common features both models are different. Still, both account well for the main experimental findings (Wagner et al. Phys. Rev. B 2005, 72, 205404). In particular, an isotope effect in desorption probabilities, the energy content of the desorbing molecules, and the scaling of these observables with laser fluence are reproduced and explained. The similarity of the results obtained with both models is traced back to the fact that, in the present case, the photodynamics takes place dominantly in the ground electronic state because the electronically excited state is rapidly quenched. The short lifetime of the excited state has also the effect that photoreaction cross sections are typically very small. An IR+vis hybrid scheme, by which the adsorbate is vibrationally excited by IR photons prior to the heating of metal electrons with the vis pulse, is shown to successfully promote the reaction even for strongly coupled adsorbate-surface systems.
Neogene magmatism and its possible causal relationship with hydrocarbon generation in SW Colombia
(2009)
The Cretaceous oil-bearing source and reservoir sedimentary succession in the Putumayo Basin, SW Colombia, was intruded by gabbroic dykes and sills. The petrological and geochemical character of the magmatic rocks shows calc- alkaline tendency, pointing to a subduction-related magmatic event. K/Ar dating of amphibole indicates a Late Miocene to Pliocene age (6.1 +/- A 0.7 Ma) for the igneous episode in the basin. Therefore, we assume the intrusions to be part of the Andean magmatism of the Northern Volcanic Zone (NVZ). The age of the intrusions has significant tectonic and economic implications because it coincides with two regional events: (1) the late Miocene/Pliocene Andean orogenic uplift of most of the sub-Andean regions in Peru, Ecuador and Colombia and (2) a pulse of hydrocarbon generation and expulsion that has reached the gas window. High La/Yb, K/Nb and La/Nb ratios, and the obtained Sr-Nd-Pb isotopic compositions suggest the involvement of subducted sediments and/or the assimilation of oceanic crust of the subducting slab. We discuss the possibility that magma chamber(s) west of the basin, below the Cordillera, did increase the heat flow in the basin causing generation and expulsion of hydrocarbons and CO2.
The Subandean fold and thrust belt of Bolivia constitutes the easternmost part of the Andean orogen that reflects thin-skinned shortening and eastward propagation of the Andean deformation front. The exact interplay of tectonics, climate, and erosion in the deposition of up to 7.5 km of late Cenozoic strata exposed in the Subandes remains unclear. To better constrain these relationships, we use four W-E industry seismic reflection profiles, eight new zircon U-Pb ages from Mio-Pliocene sedimentary strata, and cross-section balancing to evaluate the rates of thrust propagation, shortening, and deposition pinch-out migration. Eastward thrusting arrived in the Subandean belt at similar to 12.4 +/- 0.5 Ma and propagated rapidly toward the foreland unit approximately 6 Ma. This was followed by out-of- sequence deformation from ca. 4 to 2.1 Ma and by renewed eastward propagation thereafter. Our results show that the thrust-front propagation- and deposition pinch-out migration rates mimic the sediment accumulation rate. The rates of deposition pinchout migration and thrust propagation increased three- and two fold, respectively (8 mm/a; 3.3 mm/a) at 86 Ma. The three-fold increase in deposition pinch-out migration rate at this time is an indication of enhanced erosional efficiency in the hinterland, probably coupled with flexural rebound of the basin. Following the pulse of pinch-out migration, the Subandean belt witnessed rapid similar to 80 km eastward propagation of thrusting to the La Vertiente structure at 6 Ma. As there is no evidence for this event of thrust front migration being linked to an increase in shortening rate, the enhanced frontal accretion suggests a shift to supercritical wedge taper conditions. We propose that the supercritical state was due to a drop in basal strength, caused by sediment loading and pore fluid overpressure. This scenario implies that climate-controlled variation in erosional efficiency was the driver of late Miocene mass redistribution, which induced flexural rebound of the Subandean thrust belt, spreading of a large clastic wedge across the basin, and subsequent thrust-front propagation.
Recognition of an inferred Miocene marine incursion affecting areas from Colombia through Peru and Bolivia and into Argentina is essential to delineate the South American Seaway. In Bolivia, corresponding strata of inferred marine origin have been assigned to the late Miocene Yecua Formation. We carried out high-resolution delta C-13 and delta O-18 isotopic studies on 135 in situ carbonates from 3 outcrops, combined with detailed sedimentologic, paleontologic, and ichnologic analysis. Four less negative delta C-13 excursion levels were recorded that coincide well with beds containing marine body (barnacle) and trace (Ophiomorpha) fossils. These strata are interbedded with red-green beds containing mudcracks, plant roots, gypsum, and trace fossils of the continental Scoyenia ichnofacies. Our data are significant in that they show for the first time four possible short-lived marine incursions in the Bolivian central Andes during the late Miocene. The result is constrained by a new U-Pb date of 7.17 +/- 0.34 Ma at the top of Yecua strata.
Many of today's distributed computing systems in the field do not Support the migration of execution entities among computing nodes (luring runtime. The relatively static association between units of processing and computing nodes makes it difficult to implement fault-tolerant behavior or load-balancing schemes. The concept of code migration may provide a solution to the above-mentioned problems. it can be defined as the movement of processes, objects, or components from one computing node to another during system runtime in a distributed environment. With the advent of the virtual machine-based NET framework, many of the cross-language heterogeneity issues have been resolved. With the commercial implementation, the shared source "Rotor", and the open-source "Mono" implementation on hand, we have focused on cross-operating system heterogeneity issues and present interoperability and migration schemes for applications distributed over different operating systems (namely Linux and Windows 2000) as well as various NET implementations. Within this paper, we describe the integration of a migration facility with the hell) of Aspect- Oriented Programming (AOP) into the NET framework. AOP is interesting as it addresses non-functional system properties on the middleware level, without the need to manipulate lower system layers like the operating system itself. Most features required to implement object or process migration (such as reflection mechanisms or a machine-independent executable format) are already present in the NET frameworks, so the integration of such a concept is a natural extension of the system capabilities. We have implemented several proof-of-concept applications for different use case scenarios. The paper contains an experimental evaluation of the performance impact of object migration in context of those applications.
Tree size and herbivory determine below-canopy grass quality and species composition in savannahs
(2009)
Large single-standing trees are rapidly declining in savannahs, ecosystems supporting a high diversity of large herbivorous mammals. Savannah trees are important as they support both a unique flora and fauna. The herbaceous layer in particular responds to the structural and functional properties of a tree. As shrubland expands stem thickening occurs and large trees are replaced by smaller trees. Here we examine whether small trees are as effective in providing advantages for grasses growing beneath their crowns as large trees are. The role of herbivory in this positive tree- grass interaction is also investigated. We assessed soil and grass nutrient content, structural properties, and herbaceous species composition beneath trees of three size classes and under two grazing regimes in a South African savannah. We found that grass leaf content (N and P) beneath the crowns of particularly large (ca. 3.5 m) and very large trees (ca. 9 m) was as much as 40% greater than the same grass species not growing under a tree canopy, whereas nutrient contents of grasses did not differ beneath small trees (< 2.3 m). Moderate herbivory enhanced these effects slightly. Grass species composition differed beneath and beyond the tree canopy but not between tree size classes. As large trees significantly improve the grass nutrient quality for grazers in contrast to smaller trees, the decline of the former should be halted. The presence of trees further increases grass species diversity and patchiness by favouring shade- tolerant species. Both grazing wildlife and livestock will benefit from the presence of large trees because of their structural and functional importance for savannahs.
A theoretical model for the selective subsurface absorption of atomic hydrogen in a Pd(111) surface by infrared (IR) laser pulses is presented. The dynamics of the adsorbate is studied within the reduced density matrix approach. Energy and phase relaxation of the hydrogen atom are treated using the semigroup formalism. The vibrational excitation leading to subsurface absorption is performed using rationally designed pulses as well as IR laser pulses optimized on- the-fly. It is shown that dissipation can be used as a tool to transfer population to an otherwise inaccessible state via a mechanism known as "laser distillation." We demonstrate that when the reaction path is generalized from a reduced one-dimensional to full three-dimensional treatment of the system, the laser control strategy can prove very different.
Evolutionary processes play an important role in shaping the dynamics of range expansions, and selection on dispersal propensity has been demonstrated to accelerate rates of advance. Previous theory has considered only the evolution of unconditional dispersal rates, but dispersal is often more complex. For example, many species emigrate in response to crowding. Here, we use an individual-based model to investigate the evolution of density dependent dispersal into empty habitat, such as during an invasion. The landscape is represented as a lattice and dispersal between Populations follows a stepping-stone pattern. Individuals carry three 'genes' that determine their dispersal strategy when experiencing different population densities. For a stationary range we obtain results consistent with previous theoretical studies: few individuals emigrate from patches that are below equilibrium density. However, during the range expansion of a previously stationary population, we observe evolution towards dispersal strategies where considerable emigration occurs well below equilibrium density. This is true even for moderate costs to dispersal, and always results in accelerating rates of range expansion. Importantly, the evolution we observe at an expanding front depends upon fitness integrated over several generations and cannot be predicted by a consideration of lifetime reproductive success alone. We argue that a better understanding of the role of density dependent dispersal, and its evolution, in driving population dynamics is required especially within the context of range expansions.
Owen et al. [Owen. R.B.. Potts, R., Behrensmeyer, A.K., Ditchfield, P. 2008. Diatomaceous sediments and environmental change in the Pleistocene Olorgesailie Formation, southern Kenya Rift Valley. Palaeogeography, Palaeochmatology, Palaeoccology, 269. 17-37], Diatomaceous sediments and environmental change in the Pleistocene Olorgesailie Formation. southern Kenya Rift. Palaeogeography Palaeoclimatology Palaeciecology, 269, 17-37) argued that diatom assemblage variations in the Olorgesailie Formation indicate considerable environmental instability with both wetter and drier periods, contradicting the proposed period of lake stability and wet climatic conditions between ca 11 and 0.9 million years ago as proposed by Trauth et al [Trauth, M.H. Maslin, MA.. Demo. A.. Strecker, M R.. 2005. Late Cenozoic moisture history of East Africa. Science 309. 2051-2053., Trauth, M H. Mashn. M.A., Deino, A., Bergner. A G.N.. Diihnforth, M. Strecker. M.R, 2007 High- and low-latitude forcing of Plio-Pleistocene East African climate and hL.man evolution. journal of Human Evolution 53, 475-486] Contrary to the interpretation of our work by O Nen et al. [Owen. R.B, Potts, R. Behrensmeyer, A.K. Ditchfield. P. 2008], we never said that the proposed periods of large lakes were characterized by stable conditions.
The Kuramoto phase-diffusion equation is a nonlinear partial differential equation which describes the spatiotemporal evolution of a phase variable in an oscillatory reaction-diffusion system. Synchronization manifests itself in a stationary phase gradient where all phases throughout a system evolve with the same velocity, the synchronization frequency. The formation of concentric waves can be explained by local impurities of higher frequency which can entrain their surroundings. Concentric waves in synchronization also occur in heterogeneous systems, where the local frequencies are distributed randomly. We present a perturbation analysis of the synchronization frequency where the perturbation is given by the heterogeneity of natural frequencies in the system. The nonlinearity in the form of dispersion leads to an overall acceleration of the oscillation for which the expected value can be calculated from the second-order perturbation terms. We apply the theory to simple topologies, like a line or sphere, and deduce the dependence of the synchronization frequency on the size and the dimension of the oscillatory medium. We show that our theory can be extended to include rotating waves in a medium with periodic boundary conditions. By changing a system parameter, the synchronized state may become quasidegenerate. We demonstrate how perturbation theory fails at such a critical point.
The behavior of weakly coupled self-sustained oscillators can often be well described by phase equations. Here we use the paradigm of Kuramoto phase oscillators which are coupled in a network to calculate first- and second-order corrections to the frequency of the fully synchronized state for nonidentical oscillators. The topology of the underlying coupling network is reflected in the eigenvalues and eigenvectors of the network Laplacian which influence the synchronization frequency in a particular way. They characterize the importance of nodes in a network and the relations between them. Expected values for the synchronization frequency are obtained for oscillators with quenched random frequencies on a class of scale-free random networks and for a Erdoumls-Reacutenyi random network. We briefly discuss an application of the perturbation theory in the second order to network structural analysis.
The Kurancali ultramafic-mafic cumulate body, an allochthonous ophiolitic sliver in central Anatolia, is characterized by the presence of abundant hydrous phases (phlogopite, pargasite) besides augitic diopside, plagioclase, and accessory amounts of rutile, sphene, apatite, zircon, and calcite. Based on modes of the essential minerals, the olivine-orthopyroxene-free cumulates are grouped as clinopyroxenite, hydrous clinopyroxenite, phlogopitite, hornblendite, layered gabbro, and diorite. Petrographical, mineralogical and geochemical features of the rocks infer crystallization from a hydrous magma having high-K calcalkaline affinity with slightly alkaline character, and point to metasomatised mantle as the magma source. Our evidence implies that the metasomatising component, which modified the composition of the mantle wedge source rock in an intraoceanic subduction zone, was a H2O, alkali and carbonate-rich aluminosilicate fluid and/or melt, probably derived from a subducted slab. We suggest that the metasomatic agents in the subarc mantle led to the generation of a hydrous magma, which produced the Kurancali cumulates in an island-arc basement in a supra-subduction-zone setting during the closure of the Izmir-Ankara-Erzincan branch of the Alpine Neotethys Ocean.
Terrestrial-derived dissolved organic carbon (DOC) contributes significantly to the energetic basis of many aquatic food webs. Although heterotrophic bacteria are generally considered to be the sole consumers of DOC, algae and cyanobacteria of various taxonomic groups are also capable of exploiting this resource. We tested the hypothesis that algae can utilise DOC in the presence of bacteria if organic resources are supplied in intervals by photolysis of recalcitrant DOC. In short-term uptake experiments, we changed irradiation in the range of minutes. As model substrates, polymers of radiolabelled coumaric acid (PCA) were used, which during photolysis are known to release aromatic compounds comparable to terrestrial-derived and refractory DOC. Three cultured freshwater algae readily assimilated PCA photoproducts equivalent to a biomass-specific uptake of 5-60% of the bacterial competitors present. Algal substrate acquisition did not depend on whether PCA was photolysed continuously or in intervals. However, the data show that photoproducts of terrestrial DOC can be a significant resource for osmotrophic algae. In long-term growth experiments, interval light was applied one hour per day. We allowed cultured Chlamydomonas to compete for ambient DOC of low concentration. We found higher abundances of Chlamydomonas when cultures were irradiated intermittently rather than continuously. These data suggest that photolysis of DOC supports algal heterotrophy, and potentially facilitates growth, when light fluctuations are large, as during the diurnal light cycle. We concluded that osmotrophic algae can efficiently convert terrestrial carbon into the biomass of larger organisms of aquatic food webs.
We investigated the response of two populations of the barb Garra barreimiae to different light intensities (0.5-2000 lx) from a light source. Adults of both the surface (epigean) and cave (hypogean) G. barreimiae populations show photophobic behavior. A photophobic response in the cave form was seen only at higher light intensities because the cavefish are eyeless and rely on extra-retinal light receptors to detect light. In contrast, juveniles (surface and cave) showed photophilic behavior, and their preference for the photic zone of the test tank decreased with increasing age. We discuss the potential role played by photophobic behavior for the colonization of caves by previously surface- dwelling fishes.
Early Carboniferous to Permian magmatism associated with rifting within the northern foreland of the Variscan Orogen was widespread across Europe. During the long period of magmatic activity the regional tectonic setting changed across the region from early Carboniferous extension and basin formation to a rifting-wrenching style of deformation in the late Carboniferous (Stephanian) to early Permian. Wrenching and faulting were accompanied by widespread, voluminous and episodic magmatic extrusion, intrusion and underplating. This was followed by thermal relaxation and the development of the Northern and Southern Permian Basins in later Permian times. Thermal relaxation was punctuated by a Permo- Triassic phase of extension and graben formation. Ar-40/Ar-39 Ar step-heating dating for mineral separates and whole- rock samples of magmatic rocks from southern Scandinavia (Oslo Graben and south Sweden) and Rugen (north Germany) provides further radiometric evidence for three of the proposed periods of magmatic activity in the region. Latest Carboniferous to earliest Permian ages (c. 300-310 Ma) were obtained for volcanic rocks in the Oslo Graben and dolerite sills and dykes in south Sweden and north Germany. This phase can be time-correlated with magmatic activity that occurred throughout Europe during large-scale dextral wrenching that followed the Variscan Orogeny. A second phase of alkaline intrusions is confined to the Oslo Graben and related to caldera collapse around c. 275 Ma. The third, Permo- Triassic phase (c. 250 Ma) is considered to be related to a new tectonic cycle involving extension that triggered minor melting of enriched, fertile mantle.
Erosional exhumation and topography in mountain belts are temporally and spatially variable over million year timescales because of changes in both the location of deformation and climate. We investigate spatiotemporal variations in exhumation across a 150 x 250 km compartment of the NW Himalaya, India. Twenty-four new and 241 previously published apatite and zircon fission track and white mica Ar-40/Ar-39 ages are integrated with a 1-D numerical model to quantify rates and timing of exhumation alongstrike of several major structures in the Lesser, High, and Tethyan Himalaya. Analysis of thermochronometer data suggests major temporal variations in exhumation occurred in the early middle Miocene and at the Plio-Pleistocene transition. (1) Most notably, exhumation rates for the northern High Himalayan compartments were high (2-3 mm a(-1)) between similar to 23-19 and similar to 3-0 Ma and low (0.5-0.7 mm a(-1)) in between similar to 19-3 Ma. (2) Along the southern High Himalayan slopes, however, high exhumation rates of 1-2 mm a(-1) existed since 11 Ma. (3) Our thermochronology data sets are poorly correlated with present-day rainfall, local relief, and specific stream power which may likely result from (1) a lack of sensitivity of changes in crustal cooling to spatial variations in erosion at high exhumation rates (>similar to 1 mm a(-1)), (2) spatiotemporal variation in erosion not mimicking the present-day topographic or climatic conditions, or (3) the thermochronometer samples in this region having cooled under topography that only weakly resembled the modern-day topography.
We study the effects of parametric noise on a lattice network, which is locally modeled by a two-dimensional Rulkov map. We conclude that at some intermediate noise intensity, parametric noise can induce ordered circular patterns, which indicates the appearance of spatiotemporal coherence resonance in the studied lattice. With the observation of coherence-like manner in linear spatial cross-correlation, the coherence phenomena can be analyzed quantitatively.
Rising demand for food and bioenergy makes it imperative to breed for increased crop yield. Vegetative plant growth could be driven by resource acquisition or developmental programs. Metabolite profiling in 94 Arabidopsis accessions revealed that biomass correlates negatively with many metabolites, especially starch. Starch accumulates in the light and is degraded at night to provide a sustained supply of carbon for growth. Multivariate analysis revealed that starch is an integrator of the overall metabolic response. We hypothesized that this reflects variation in a regulatory network that balances growth with the carbon supply. Transcript profiling in 21 accessions revealed coordinated changes of transcripts of more than 70 carbon-regulated genes and identified 2 genes (myo-inositol-1- phosphate synthase, a Kelch-domain protein) whose transcripts correlate with biomass. The impact of allelic variation at these 2 loci was shown by association mapping, identifying them as candidate lead genes with the potential to increase biomass production.
It is well established that reproductive isolation often arises from genome incompatibilities and that genes encoding reproductive traits are less prone to introgression. Hybrid zones of Mytilus trossulus and Mytilus edulis provide an intriguing model to assess reproductive isolation. Although gene flow is restricted in North America, introgression is pervasive in the Baltic. This study aimed at analyzing the shape of multilocus clines across the Baltic contact zone between M. edulis and M. trossulus to infer mechanisms of restriction to gene flow. We use maximum likelihood methods to construct the best fitting individual clines for five markers located on biparentally inherited autosomes and paternally and maternally inherited mitochondrial DNA (mtDNA). Strong cline shape differences among markers suggest that reproductive isolation arising from genome-wide incompatibilities is weak, and that these discrepancies possibly result from genetic drift, hybrid zone movement or marker-specific selection. However, the finding of a common cline center for M7 lysin (involved in fertilization) and paternally transmitted mtDNA (causing nuclear-mitochondrial incompatibilities in hybrids) suggest that these loci may play a role in incomplete reproductive isolation.
The mussel Mytilus edulis can be used as model to study the molecular basis of reproductive isolation because this species maintains its species integrity, despite of hybridizing in zones of contact with the closely related species M. trossulus or M. galloprovincialis. This study uses selective antibody production by means of hybridoma technology to identify molecules which are involved in sperm function of M. edulis. Fragmented sperm were injected into mice and 25 hybridoma cell clones were established to obtain monoclonal antibodies (mAb). Five clones were identified producing mAb targeting molecules putatively involved in sperm function based on enzyme immunoassays, dot and Western blotting as well as immunostaining of tissue sections. Specific localization of these mAb targets on sperm and partly also in somatic tissue suggests that all five antibodies bind to different molecules. The targets of the mAb obtained from clone G26-AG8 were identified using mass spectrometry (nano-LC-ESI-MS/MS) as M6 and M7 lysin. These acrosomal proteins have egg vitelline lyses function and are highly similar (76%) which explains the cross reactivity of mAb G26- AG8. Furthermore, M7 lysin was recently shown to be under strong positive selection suggesting a role in interspecific reproductive isolation. This study shows that M6 and M7 lysin are not only found in the sperm acrosome but also in male somatic tissue of the mantle and the posterior adductor muscle, while being completely absent in females. The monoclonal antibody G26-AG8 described here will allow elucidating M7/M6 lysin function in somatic and gonad tissue of adult and developing animals.
Laser flash photolysis is applied to study the recombination reaction of lophyl radicals in ionic liquids in comparison with dimethylsulfoxide as an example of a traditional organic solvent. The latter exhibits a similar micropolarity as the ionic liquids. The ionic liquids investigated are 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (1), 1-hexyl-3-methylimidazolium hexafluorophosphate (2), and 1-butyl-3- methylimidazolium tetafluoroborate (3). The recombination of the photolytic generated lophyl radicals occur significantly faster in the ionic liquids than expected from their macroscopic viscosities and is a specific effect of these ionic liquids. On the other hand, this reaction can be compared with the macroscopic viscosity in the case of dimethylsulfoxide. Activation parameters obtained for lophyl radical recombination suggest different, anion-dependent mechanistic effects. Quantum chemical calculations based on density functional theory provide a deeper insight of the molecular properties of the lophyl radical and its precursor. Thus, excitation energies, spin densities, molar volumes, and partial charges are calculated. Calculations show a spread of spin density over the three carbon atoms of the imidazolyl moiety, while only low spin density is calculated for the nitrogens.
Orogenic plateaus are extensive, high-elevation areas with low internal relief that have been attributed to deep-seated and/or climate-driven surface processes. In the latter case, models predict that lateral plateau growth results from increasing aridity along the margins as range uplift shields the orogen interior from precipitation. We analyze the spatiotemporal progression of basin isolation and filling at the eastern margin of the Puna Plateau of the Argentine Andes to determine if the topography predicted by such models is observed. We find that the timing of basin filling and reexcavation is variable, suggesting nonsystematic plateau growth. Instead, the Airy isostatically compensated component of topography constitutes the majority of the mean elevation gain between the foreland and the plateau. This indicates that deep-seated phenomena, such as changes in crustal thickness and/or lateral density, are required to produce high plateau elevations. In contrast, the frequency of the uncompensated topography within the plateau and in the adjacent foreland that is interrupted by ranges appears similar, although the amplitude of this topographic component increases east of the plateau. Combined with sedimentologic observations, we infer that the low internal relief of the plateau likely results from increased aridity and sediment storage within the plateau and along its eastern margin.
We investigate the dielectric properties and electric breakdown strength of subpercolative composites of conductive carbon black particles in a rubber insulating matrix. A significant increase in the permittivity in the vicinity of the insulator to conductor transition was observed, with relatively low increases in dielectric loss; however, a rapid decrease in electric breakdown strength was inevitable. A steplike feature was ascribed to agglomeration effects. The low ultimate values of the electric field strength of such composites appear to prohibit practical use.
Why animals can't act
(2009)
Given the many marvelous things animals can do and moreover the success we have in employing the intentional stance towards animals, it seems to be almost unthinkable to say that animals could not act at all. Nonetheless, this is exactly what I argue for. I claim that strictly speaking there is no animal action, only behaviour. I defend this claim in three steps. Firstly, I recapitulate some of the weighty grounds that speak in favour of animal agency. Secondly, I explain why I still doubt that animals act. The argument is that the account of agency that I take to be the most attractive one entails that animals can't act. Since this account of agency is non-standard, I spend the bulk of the paper with providing a sketch of what, according to it, actions are. Finally, I explain why it is still so natural and promising to regard animals as agents, although in fact they aren't. As one might put it: of course they act, only strictly speaking they don't.
Current-voltage analysis of single-carrier transport is a popular method for the determination of charge carrier mobilities in organic semiconductors. Although in widespread use for the analysis of hole transport, only a few reports can be found where the method was applied to electron transport. Here, we summarize the experimental difficulties related to the metal electrode leakage currents and nonlinear differential resistance (NDR) effects and explain their origin. We present a modified preparation technique for the metal electrodes and show that it significantly increases the reliability of such measurements. It allows to produce test devices with low leakage currents and without NDR even for thin organic layers. Metal oxides were often discussed as a possible cause of NDR. Our measurements on forcibly oxidized metal electrodes demonstrate that oxide layers are not exclusively responsible for NDR effects. We present electron transport data for two electron-conducting polymers often applied in all-polymer solar cells for a large variety of layer thicknesses and temperatures. The results can be explained by established exponential trapping models.
In this publication we present an extension of the standard model within the framework of Connes' noncommutative geometry. The model presented here is based on a minimal spectral triple which contains the standard model particles, new vectorlike fermions, and a new U(1) gauge subgroup. Additionally a new complex scalar field appears that couples to the right-handed neutrino, the new fermions, and the standard Higgs particle. The bosonic part of the action is given by the spectral action which also determines relations among the gauge couplings, the quartic scalar couplings, and the Yukawa couplings at a cutoff energy of similar to 10(17) GeV. We investigate the renormalization group flow of these relations. The low energy behavior allows to constrain the Higgs mass, the mass of the new scalar, and the mixing between these two scalar fields.
This paper provides a complete list of Krajewski diagrams representing the standard model of particle physics. We will give the possible representations of the algebra and the anomaly free lifts which provide the representation of the standard model gauge group on the fermionic Hilbert space. The algebra representations following from the Krajewski diagrams are not complete in the sense that the corresponding spectral triples do not necessarily obey to the axiom of Poincare duality. This defect may be repaired by adding new particles to the model, i.e., by building models beyond the standard model. The aim of this list of finite spectral triples (up to Poincare duality) is therefore to provide a basis for model building beyond the standard model.
In this paper we will implement the inverse seesaw mechanism into the noncommutative framework on the basis of the AC extension of the standard model. The main difference from the classical AC model is the chiral nature of the AC fermions with respect to a U(1)(X) extension of the standard model gauge group. It is this extension which allows us to couple the right-handed neutrinos via a gauge invariant mass term to left-handed A particles. The natural scale of these gauge invariant masses is of the order of 10(17) GeV while the Dirac masses of the neutrino and the AC particles are generated dynamically and are therefore much smaller (similar to 1 to similar to 10(6) GeV). From this configuration, a working inverse seesaw mechanism for the neutrinos is obtained.
A reconstruction of Milankovitch to millennial-scale variability of sea surface temperature (SST) and sea surface productivity in the Pleistocene midlatitude North Atlantic Ocean (marine isotope stage (MIS) 16-9) and its relationship to ice sheet instability was carried out on sediments from Integrated Ocean Drilling Program (IODP) Site U1313. This reconstruction is based on alkenone and n-alkane concentrations, U-37(K)' index, total organic carbon (TOC) and carbonate contents, X-ray diffraction data, magnetic susceptibility, and accumulation rates. Increased input of ice-rafted debris occurred during MIS 16, 12, and 10, characterized by high concentrations of dolomite, quartz, and feldspars and elevated accumulation rates of terrigenous matter. Minimum input values of terrigenous matter, on the other hand, were determined for MIS 13 and 11. Peak values of dolomite, coinciding with quartz, plagioclase, and kalifeldspar peaks and maxima in long-chain n-alkanes indicative for land plants, are interpreted as Heinrich-like events related to sudden instability of the Laurentide Ice Sheet during early and late (deglacial) phases of the glacials. The coincidence of increased TOC values with elevated absolute concentrations of alkenones suggests increased glacial productivity, probably due to a more southern position of the Polar Front. Alkenone-based SST reached absolute maxima of about 19 degrees C during MIS 11.3 and absolute minima of <10 degrees C during MIS 12 and 10. Within MIS 11, prominent cooling events (MIS 11.22 and 11.24) occurred. The absolute SST minima recorded directly before and after the glacial maxima MIS 10.2 and 12.2 are related to Heinrich-like event meltwater pulses, as supported by the coincidence of SST minima and maxima in C-37:4 alkenones and dolomite. These sudden meltwater pulses, especially during terminations IV and V, probably caused a collapse of phytoplankton productivity as indicated by the distinct drop in alkenone concentrations. Ice sheet disintegration and subsequent surges and outbursts of icebergs and meltwater discharge may have been triggered by increased insolation in the northern high latitudes.
Plant communities can be affected both by arbuscular mycorrhizal fungi (AMF) and hemiparasitic plants. However, little is known about the interactive effects of these two biotic factors on the productivity and diversity of plant communities. To address this question, we set up a greenhouse study in which different AMF inocula and a hemiparasitic plant (Rhinanthus minor) were added to experimental grassland communities in a fully factorial design. In addition, single plants of each species in the grassland community were grown with the same treatments to distinguish direct AMF effects from indirect effects via plant competition. We found that AMF changed plant community structure by influencing the plant species differently. At the community level, AMF decreased the productivity by 15-24%, depending on the particular AMF treatment, mainly because two dominant species, Holcus lanatus and Plantago lanceolata, showed a negative mycorrhizal dependency. Concomitantly, plant diversity increased due to AMF inoculation and was highest in the treatment with a combination of two commercial AM strains. AMF had a positive effect on growth of the hemiparasite, and thereby induced a negative impact of the hemiparasite on host plant biomass which was not found in non-inoculated communities. However, the hemiparasite did not increase plant diversity. Our results highlight the importance of interactions with soil microbes for plant community structure and that these indirect effects can vary among AMF treatments. We conclude that mutualistic interactions with AMF, but not antagonistic interactions with a root hemiparasite, promote plant diversity in this grassland community.
Active motor processes are present in many sensory systems to enhance perception. In the human visual system, miniature eye movements are produced involuntarily and unconsciously when we fixate a stationary target. These fixational eye movements represent self-generated noise which serves important perceptual functions. Here we investigate fixational eye movements under the influence of external noise. In a two-choice discrimination task, the target stimulus performed a random walk with varying noise intensity. We observe noise-enhanced discrimination of the target stimulus characterized by a U-shaped curve of manual response times as a function of the diffusion constant of the stimulus. Based on the experiments, we develop a stochastic information-accumulator model for stimulus discrimination in a noisy environment. Our results provide a new explanation for the constructive role of fixational eye movements in visual perception.
An efficient electrocatalytic biosensor for sulfite detection was developed by co-immobilizing sulfite oxidase and cytochrome c with polyaniline sulfonic acid in a layer-by-layer assembly. QCM, UV-Vis spectroscopy and cyclic voltammetry revealed increasing loading of electrochemically active protein with the formation of multilayers. The sensor operates reagentless at low working potential. A catalytic oxidation current was detected in the presence of sulfite at the modified gold electrode, polarized at +0.1 V ( vs. Ag/AgCl 1 M KCl). The stability of the biosensor performance was characterized and optimized. A 17-bilayer electrode has a linear range between 1 and 60 mu M sulfite with a sensitivity of 2.19 mA M-1 sulfite and a response time of 2 min. The electrode retained a stable response for 3 days with a serial reproducibility of 3.8% and lost 20% of sensitivity after 5 days of operation. It is possible to store the sensor in a dry state for more than 2 months. The multilayer electrode was used for determination of sulfite in unspiked and spiked samples of red and white wine. The recovery and the specificity of the signals were evaluated for each sample.
The aim of this study was to investigate the effects of three different forms of strategy instruction on 210 elementary-school students' reading comprehension. Students were assigned to any one of three intervention conditions or to a traditional instruction condition (control condition). Training students were taught four reading strategies (summarizing, questioning, clarifying, predicting) and practiced these strategies in small groups (reciprocal teaching), pairs, or instructor-guided small groups. At both the post- and follow-up test the intervention students attained higher scores on an experiment-developed task of reading comprehension and strategy use than the control students who received traditional instruction. Furthermore, students who practiced reciprocal teaching in small groups outperformed use than the control students who received traditional instruction groups on a standardized reading comprehension test.
Drawing on works of literature, philosophy and art the author tries to unearthen the multiple meanings of tears and crying in the history of the fine arts. The essay spans from pictures of the earliest known representations of tears in the Middle Ages to the tears found in photographies of the Modern Arts of nowadays.
Enhanced water temperatures promote the occurrence of cyanobacterial blooms, which may be detrimental to aquatic herbivores. Especially, the often-dominant crustaceans could be negatively affected because cyanobacteria are deficient in phytosterols, which are required by the crustaceans to form the membrane component cholesterol, which in turn plays a role in thermal adaptation. Here, we determined the influence of temperature on growth, reproduction and the allocation of dietary sterol into somatic tissues and eggs of the keystone species Daphnia magna raised along a dietary cholesterol gradient. Mass-specific growth rates of D. magna increased with the increasing availability of dietary cholesterol up to an incipient limiting level, which increased with increasing temperature. This indicates a higher demand for cholesterol for growth at higher temperatures and may explain the consistently smaller clutch sizes of reproducing females at the highest temperature. The cholesterol content of the individuals increased with increasing dietary cholesterol; this increase was enhanced at higher temperatures, indicating a higher demand for cholesterol for tissues and probably specifically for membranes. Surprisingly, the daphnids showed different allocation strategies with regard to temperature and dietary sterol availability. The cholesterol content of eggs was enhanced at higher temperature, which suggested that females allocate more cholesterol to their offspring, presumably to ensure sufficient egg development. When dietary cholesterol was limiting, however, females did not allocate more cholesterol to their eggs. Our data suggest that during cyanobacterial blooms, a potential dietary sterol limitation of Daphnia can be intensified at higher water temperatures, which can occur with global warming.
Background and purpose: Although carbon monoxide (CO) can modulate inflammatory processes, the influence of CO on adhesion molecules is less clear. This might be due to the limited amount of CO generated by haem degradation. We therefore tested the ability of a CO releasing molecule (CORM-3), used in supra-physiological concentrations, to modulate the expression of vascular cell adhesion molecule (VCAM)-1 and E-selectin on endothelial cells and the mechanism(s) involved. Experimental approach: Human umbilical vein endothelial cells (HUVECs) were stimulated with tumour necrosis factor (TNF)-alpha in the presence or absence of CORM-3. The influence of CORM-3 on VCAM-1 and E- selectin expression and the nuclear factor (NF)-kappa B pathway was assessed by flow cytometry, Western blotting and electrophoretic mobility shift assay. Key results: CORM-3 inhibited the expression of VCAM-1 and E-selectin on TNF-alpha- stimulated HUVEC. VCAM-1 expression was also inhibited when CORM-3 was added 24 h after TNF-alpha stimulation or when TNF-alpha was removed. This was paralleled by deactivation of NF-kappa B and a reduction in VCAM-1 mRNA. Although TNF- alpha removal was more effective in this regard, VCAM-1 protein was down-regulated more rapidly when CORM-3 was added. CORM-3 induced haem oxygenase-1 (HO-1) in a dose- and time-dependent manner, mediated by the transcription factor, Nrf2. CORM-3 was still able to down-regulate VCAM-1 expression in HUVEC transfected with siRNA for HO-1 or Nrf2. Conclusions and implications: Down-regulation of VCAM and E-selectin expression induced by CORM-3 was independent of HO-1 up- regulation and was predominantly due to inhibition of sustained NF-kappa B activation.
Why does Cecil Beaton choose Jackson Pollock paintings as backdrops for his fashion shoot for American Vogue in March of 1951? Beaton's photographs represent a special, highly ambivalent moment in the development of an American aesthetic identity in and through Vogue. His clearly "European gaze" instrumentalizes Pollock's paintings for his own purposes and highlights the long-lasting ideological conflict between European design and American identity. A close examination of the role of the magazine in shaping the self-image of America's upper classes, as well as of the function of these images within the parameters of the magazine itself and of abstract art within the series, offers an enriched understanding of the relationship of art and fashion in Vogue. These notorious images become the occasion for an analysis of the relationship between America's avant-garde and Vogue, the integration of their works into the structure of the magazine and their function therein. Situating the photographs within the socio- historical context of the magazine offers insight, as well, into Beaton's photos as a factor in an internal conflict at the magazine arising from the clash of Vogue's orientation on European and French fashion and lifestyle and its identity as a magazine for a specific, American upper-class audience. While Beaton's pictures incorporate the "strength" of American creativity, these images do not assert the equality of American with French design. The issue is no longer a fundamental legitimization of American design; much more, the newly reestablished dominance of the French as a creative force in fashion after the introduction of Dior's New Look had to be balanced with American reality. Beaton's images attempt to stage the newly reborn longing for a "feeling of Frenchness" and to integrate it with an essentially-American creativity in the New World through the use of Pollock's paintings.
Linear amphiphilic diblock and ternary triblock copolymers were synthesized by the RAFT method in two successive steps using a poly(ethylene oxide) (PEO) macrochain transfer agent, butyl or 2-ethylhexyl acrylate, and 1H, 1H, 2H, 2H-perfluorodecyl acrylate. The diblock and the triblock copolymers, which consist of a hydrophilic, a lipophilic, and a short fluorophilic block, self-assemble in water into spherical micellar aggregates. Imaging by cryogenic transmission electron microscopy (cryo-TEM) revealed that the micellar cores of the aggregates made from these "triphilic" copolymers can undergo local phase separation to form a unique ultrastructure. In these multicompartment micelles, it appears that extended nonspherical domains, presumably made of nanocrystallites of the fluorocarbon block, are embedded in the hydrocarbon matrix forming the spherical micellar core. This novel internal structure of a micellar core is attributed to the mutual incompatibility of the fluorocarbon and hydrocarbon side chains in combination with the tendency of the used fluorocarbon acrylate monomer to undergo side-chain crystallization.
The interaction between topicalization and structural constraints : evidence from Yucatec Maya
(2009)
This article deals with the syntactic and pragmatic properties of left dislocated constituents in Yucatec Maya. It has been argued that these constituents are topics, which implies that a particular structural configuration, namely left dislocation displays a 1:1 correspondence to a particular discourse function. We present evidence that the discourse properties of left dislocation are not uniform: only a subset of the left dislocated constituents qualify as topics in the strict sense, while other instances of left dislocation are better explained if we assume a structural constraint that bans the postverbal occurrence of subject constituents in a particular syntactic configuration. Our empirical findings show that though the occurrence of word order possibilities in discourse is not random, it is not necessarily determined by a unique licensing condition.
Georgian is famous for its word order flexibility: all permutations of constituent order are possible and the choice among them is primarily determined by information structure. In this paper, we show that word order is not the only means to encode information structure in this language, but it is used in combination with sentence prosody. After a preliminary description of the use of prosodic phrasing and intonation for this purpose, we address the question of the interrelation between these two strategies. Based on experimental evidence, we investigate the interaction of focus with word order and prosody, and we conclude that some aspects of word order variation are pragmatically vacuous and can be accommodated in any context if they are realized with an appropriate prosodic structure, while other word order phenomena are quite restrictive and cannot be overridden through prosodic manipulations.
The dual isotopes of deep nitrate as a constraint on the cycle and budget of oceanic fixed nitrogen
(2009)
We compare the output of an 18-box geochemical model of the ocean with measurements to investigate the controls on both the mean values and variation of nitrate delta N-15 and delta O-18 in the ocean interior. The delta O-18 of nitrate is our focus because it has been explored less in previous work. Denitrification raises the delta N-15 and delta O-18 of mean ocean nitrate by equal amounts above their input values for N-2 fixation (for delta N-15) and nitrification (for delta O-18), generating parallel gradients in the delta N-15 and delta O-18 of deep ocean nitrate. Partial nitrate assimilation in the photic zone also causes equivalent increases in the delta N-15 and delta O-18 of the residual nitrate that can be transported into the interior. However, the regeneration and nitrification of sinking N can be said to decouple the N and O isotopes of deep ocean nitrate, especially when the sinking N is produced in a low latitude region, where nitrate consumption is effectively complete. The delta N-15 of the regenerated nitrate is equivalent to that originally consumed, whereas the regeneration replaces nitrate previously elevated in delta O-18 due to denitrification or nitrate assimilation with nitrate having the delta O-18 of nitrification. This lowers the delta O-18 of mean ocean nitrate and weakens nitrate delta O-18 gradients in the interior relative to those in delta N-15. This decoupling is characterized and quantified in the box model, and agreement with data shows its clear importance in the real ocean. At the same time, the model appears to generate overly strong gradients in both delta O-18 and delta N-15 within the ocean interior and a mean ocean nitrate delta O-18 that is higher than measured. This may be due to, in the model, too strong an impact of partial nitrate assimilation in the Southern Ocean on the delta N-15 and delta O-18 of preformed nitrate and/or too little cycling of intermediate-depth nitrate through the low latitude photic zone.
Culture studies of denitrifying bacteria predict that denitrification will generate equivalent gradients in the delta N-15 and delta O-18 of deep ocean nitrate. A depth profile of nitrate isotopes from the Hawaii Ocean Time-series Station ALOHA shows less of an increase in delta O-18 than in delta N-15 as one ascends from abyssal waters into the denitrification-impacted mid-depth waters. A box model of the ocean nitrate N and O isotopes indicates that this is the effect of the low latitude nitrate assimilation/regeneration cycle: organic N sinking out of the surface spreads the high-delta N-15 signal of pelagic denitrification into waters well below and beyond the suboxic zone, whereas the nitrate delta O-18 signal of denitrification can only be transmitted by circulation in the interior.
We consider the dynamics of monodisperse bubbly liquid confined by two plane solid walls and subject to small- amplitude high-frequency transverse oscillations. The period of these oscillations is assumed small in comparison with typical relaxation times for a single bubble but comparable with the period of volume eigenoscillations. The time- averaged description accounting for the two-way coupling between the liquid and the bubbles and for the diffusivity of bubbles is applied. We find nonuniform steady states with the liquid quiescent on average. At relatively low frequencies, accumulation of bubbles either at the walls or in planes parallel to the walls is detected. These one- dimensional states are shown to be unstable. At relatively high frequencies, this accumulation is found at the central plane and the solution is stable.
Covalently crosslinked PEI hydrogels are efficient templates for calcium phosphate mineralization in SBF. In contrast to the PEI hydrogels, non-crosslinked PEI does not lead to calcium phosphate nucleation and growth in SBF. The precipitate is a mixture of brushite and hydroxyapatite. The PEI/calcium phosphate composite material exhibits a sponge like morphology and a chemical composition that is interesting for implants. Cytotoxicity tests using Dictyostelium discoideum amoebae show that both the non-mineralized and mineralized hydrogels have a very low cytotoxicity. This suggests that next generation PEI hydrogels, where also the degradation products are non-toxic, could be interesting for biomedical applications.
Calcium phosphate mineralization from aqueous solution in the presence of organic growth modifiers has been intensely studied in the recent past. This is mostly due to potential applications of the resulting composites in the biomaterials field. Polymers in particular are efficient growth modifiers. As a result, there has been a large amount of work on polymeric growth modifiers. Interestingly, however, relatively little work has been done on polycationic additives. The current paper shows that poly(ethylene oxide)b-poly(L-lysine) block copolymers lead to an interesting morphology of calcium phosphate precipitated at room temperature and subjected to a mild heat treatment at 85 degrees C. Electron microscopy, synchrotron X-ray diffraction, and porosity analysis show that a (somewhat) porous material with channel-like features forms. Closer inspection using transmission electron microscopy shows that the channels are probably not real channels. Much rather the morphology is the result of the aggregation of ca. 100-nm-sized rodlike primary particles, which changes upon drying to exhibit the observed channel-like features. Comparison experiments conducted in the absence of polymer and with poly(ethylene oxide)-b-poly(L-glutamate) show that these features only form in the presence of the polycationic poly(L-lysine) block, suggesting a distinct interaction of the polycation with either the crystal or the phosphate ions prior to mineralization.
We propose a new mechanism which explains the existence of enormously sharp edges in the rings of Saturn. This mechanism is based on the synchronization phenomenon due to which the epicycle rotational phases of particles in the ring, under certain conditions, become synchronized with the phase of external satellite, e. g. with the phase of Mimas in the case of the outer B ring edge. This synchronization eliminates collisions between particles and suppresses the diffusion induced by collisions by orders of magnitude. The minimum of the diffusion is reached at the centre of the synchronization regime corresponding to the ratio 2:1 between the orbital frequency at the edge of B ring and the orbital frequency of Mimas. The synchronization theory gives the sharpness of the edge in a few tens of meters that is in agreement with available observations.
We analyzed mtDNA polymorphisms (parts of control region, ND5, ND2, Cytb, 12S, together 902 bp) in 59 scat and 18 tissue samples from 13 Indian populations of the critically endangered Indian tiger (Panthera tigris tigris), along with zoo animals as reference. Northern tiger populations exhibit two unique haplotypes suggesting genetic isolation. Western populations from Sariska (extinct in 2004) and Ranthambore are genetically similar, such that Ranthambore could serve as a source for reintroduction in Sariska. Zoo populations maintain mitochondrial lineages that are rare or absent in the wild.
The topic of this essay is akrasia in its most paradoxical kind, as it appears to us in the emblem of Medea. The argument starts with the claim that the problem with akrasia is especially a problem of rational potentiality: to understand it philosophically, we are forced to embrace the idea that its possibility is immanent to the rational capacity of action. By discussing elements of Plato's, Aristotle's, and Davidson's explanations of practical irrationality, the argument proceeds to demonstrate that the reasons a practical capacity provides exist as "forces", that rational forces are structurally in excess with respect to their normative statuses, and that Medea is the mythical figure par excellence of such an immanent excess of rational agency. On account of these insights, we can begin to understand that akrasia is not only a kind of failure, or incapacity, but entails the very possibility of a "metamorphosis" of the subject.
On the basis of our data from telephone and face-to-face conversations between adolescent girls and young women of ethnic Turkish background who live in Berlin, we will describe some characteristic structures of the ethnic style of speaking that is called 'Turkendeutsch', 'Turkenslang', 'Kanak sprak' or the like. In our data, this style of speaking is not deployed throughout the speakers' conversations, butonly in particular turns and turn-constructional units (TCUs). The utterances most typical of this style exhibit specific combinations of syntactic and prosodic features that are unusual for colloquial and/or regionalized varieties of German. Among the structures recurrently found are specific kinds of pre- and post-positioned constituents before and after their 'host' sentences, the separation of turn-constructional units into very short prosodic units, the deployment of both lexical stress as well as utterance accentuation as a resource for stylistic variation, and the constitution of particular rhythmic patterns. In our paper, we will discuss some of these structures and show how they arc used its a resource to achieve particular tasks in conversational interaction.
Accessory minerals of the Caledonian Rumburk granite are investigated to gain insight into its magmatic and post-magmatic evolution history. Recent geothermometers calibrated for trace elements in rutile (Zr), zircon (Ti), and quartz (Ti) were used to determine mineral-formation temperatures, which are compared with T data obtained from melt and fluid-inclusion Studies on quartz. Improved electron-microprobe analytical conditions allowed distinguishing several generations of rutile. Submicron-sized rutile needles included in quartz crystallized at around 739 +/- 13 degrees C and, thus, are evidently magmatic. Simultaneous crystallization of the high-T rutile and quartz is the favoured concept compared with an exsolution model for the needles. Th-U-total Pb dating of xenotime-(Y) by electron microprobe yielded a bimodal age distribution of 494 +/- 8 Ma (2 sigma; n = 44) and 311 +/- 8 Ma (2 sigma; n = 48), which is missing in monazite-(Ce). The older age correlates with the early Ordovician granite emplacement age Suggested by earlier isotopic Studies. The younger Carboniferous age also may be geologically reasonable, because the granite experienced a minor tectonothermal overprint during the Variscan orogenesis. However, whether this event has caused the resetting of the isotopic system in the xenotime is uncertain. This also holds for the age of the partial breakdown of monazite and xenotime into reaction coronas composed of fluorapatite, allanite-(Ce), epidote +/- clinozoisite. This alteration assemblage was likely produced already during autometasomatic reworking of the solidifying magma in Ordovician time, but it cannot be excluded that it relates to a Carboniferous fluid imprint connected with late-Variscan processes.
The post-Variscan uplift of the western Anti-Atlas Precambrian core is studied by zircon fission track (ZFT) analysis of ten samples of granites and schists from the Kerdous and Ifni inliers. All samples yield Carboniferous ZFT ages ranging from 358 +/- 31 Ma to 319 +/- 32 Ma, with nine dates younger than 338 +/- 35 Ma. The weighted mean age calculated for these nine samples is 328 +/- 30 Ma. These results compare with the available K-Ar datings of white mica and biotite from the same rocks or from the overlying Ediacaran-Cambrian low-grade metasediments. The fact that different systems with distinct closure temperatures yield similar ages suggests the occurrence of a short Carboniferous thermal event followed by rapid cooling. Consistent with the regional geological framework, the thermal event is assigned to the Variscan folding, being followed by rapid exhumation and cooling related to the post-folding erosion. To cite this article: S. Sebti et aL, C. R. Geoscience 341 (2009).
Geothermobarometric, radiogenic isotopic and thermochronologic data are used to track the influence of an ancient continental margin (Western Province) on development of an adjacent Carboniferous-Cretaceous magmatic arc (Outboard Median Batholith) in Fiordland, New Zealand. The data show a record of complicated Mesozoic Gondwana margin growth. Paragneiss within the Outboard Median Batholith is of Carboniferous to Jurassic age and records burial to middle crustal depths in Late Jurassic-Early Cretaceous during subduction-related plutonism and arc thickening. In contrast, Western Province metasedimentary rocks in the area of study immediately west of the Outboard Median Batholith are Late Cambrian-Early Ordovician in age, recrystallized at the amphibolite facies in the Late Devonian-Early Carboniferous and exhibit no evidence for Mesozoic textural or isotopic reequilibration. A phase of deformation, between 128 and 116 Ma deformed, exhumed, and cooled the Outboard Median Batholith to greenschist facies temperatures, while large parts of the Western Province underwent >= 9 kbar metamorphic conditions. Zircon grains from Mesozoic inboard plutons are isotopically more evolved (epsilon Hf(t) = +2.3 to +4.0) than those in the Outboard Median Batholith (epsilon Hf(t) = +9.4 to +11.1). The contrasting zircon Hf isotope ratios, absence of S-type plutons or Proterozoic-Early Paleozoic inherited zircon, and the apparent absence of Early Paleozoic metasedimentary rocks indicates that the Outboard Median Batholith is unlikely to be underlain by the Western Province continental lithosphere. The new data are consistent with the Outboard Median Batholith representing an allochthonous (although not necessarily exotic) arc that was juxtaposed onto the Gondwana continental margin along the intervening Grebe Mylonite Zone.
R. Sekuler, P. Tynan, and E. Levinson (1973) found that when 2 characters are presented side-by-side with a short onset asynchrony, subjectively, they often appear in a "first-left, then-right" order. The authors of this article conducted 6 experiments in which observers judged the temporal order (TOJs) in which 2 digits were presented. They found a consistent TOJ benefit (larger d') when the numerically smaller digit was presented first, even though this semantic information was irrelevant to the task and unrelated to the correct response. They concluded that digits located to the left of the mental number line are transmitted faster to a central comparison stage, which represents an "internal counterpart" to the Sekuler et al. (1973) finding regarding external locations. A corresponding benefit is found for letters pairs (e.g., A-Z) and also for mixed digit-letter pairs (e.g., I-Z).
This article addresses the different institutional and cultural contexts which must be considered when implementing E-Government in sub-Saharan Africa. Although E-Government is a global phenomenon, simply transferring ICT solutions and related organizational concepts from developed to developing countries seems inappropriate. E-Government undoubtedly has the potential to reduce administrative and development problems. However, it is obvious that compared to developed countries, additional effort is necessary when implementing E-Government in developing countries. More than in developed countries, the different initial institutional, cultural, and wider administrative contexts must be considered to avoid unintended effects. It is oversimplifying the issue to merely state that E-Government projects fail in Africa and other developing regions. Although E-Government in African countries lags far behind developed countries, this should be considered more as a state failure or lack of capacity in general. In particular, the different administrative contexts and rationalities must be taken into an account when implementing E-Government projects and strategies. Therefore, especially for African countries, a context-oriented approach seems to be a more promising route to the successful implementation of E-Government. The results of this approach may not seem ambitious from a western perspective, but could contribute to the solution of real-life and development problems in African societies.
The ellipticity of boundary value problems on a smooth manifold with boundary relies on a two-component principal symbolic structure (sigma(psi), sigma(partial derivative)), consisting of interior and boundary symbols. In the case of a smooth edge on manifolds with boundary, we have a third symbolic component, namely, the edge symbol sigma(boolean AND), referring to extra conditions on the edge, analogously as boundary conditions. Apart from such conditions 'in integral form' there may exist singular trace conditions, investigated in Kapanadze et al., Internal Equations and Operator Theory, 61, 241-279, 2008 on 'closed' manifolds with edge. Here, we concentrate on the phenomena in combination with boundary conditions and edge problem.
The centrosome is the main microtubule-organizing center and constitutes the largest protein complex in a eukaryotic cell. The Dictyostelium centrosome is an established model for acentriolar centrosomes and it consists of a layered core structure Surrounded by a so-called corona, which harbors microtubule nucleation complexes. We have identified 34 new centrosomal candidate proteins through mass spectrometrical analysis of the proteome of isolated Dictyostelium centrosomes. Here we present a characterization of 12 centrosomal candidate proteins all featuring coiled coil regions and low expression levels, which are the most common attributes of centrosomal proteins. We used GFP fusion proteins to localize the candidate proteins in whole cells and on microtubule-free, isolated centrosomes. Thus we were able to identify nine new genuine centrosomal proteins including a putative orthologue of Cep192, an interaction partner of polo-like kinase 4 in human centriole biogenesis. In this respect, centrosomal localization of the only polo-like kinase in Dictyostelium, Pik, is also shown in this work. Using confocal deconvolution microscopy, four components, CP39, CP55, CP75, and CP91 could be clearly assigned to the so far almost uncharacterized centrosomal core structure, while CP148 and Cep192 localized to a zone between that of corona marker and core proteins. Finally, CP103 and CP248 were constituents of the corona. In contrast, NE81 was localized at the nuclear envelope and three others, an orthologue of the spindle checkpoint component Mad1, the novel Cenp68, and the centrosomal CP248 were observed at the centromeres, which are clustered and linked to the centrosome throughout the entire cell cycle. Cell Motil. Cytoskeleton 66: 915-928, 2009.
Centrosomal attachment to nuclei is crucial for proper mitosis and nuclear positioning in various organisms, and generally involves Sun-family proteins located at the inner nuclear envelope. There is still no common scheme for the outer nuclear membrane proteins interacting with Sun I in centrosome/nucleus attachment. Here we propose a model in which Sun1 mediates a physical link between centrosomes and clustered centromeres through both nuclear membranes in Dictyostelium. For the first time we provide a detailed microscopic analysis of the centrosomal and nuclear envelope localization of endogenous Dictyostelium Sun1 during interphase and mitosis. By immunogold electron microscopy we show that Sun1 is a resident of both nuclear membranes. Disruption of Sun1 function by overexpression of full-length GFP-Sun1 or a GFP-Sun-domain deletion construct revealed not only the established function in centrosome/nucleus attachment and maintenance of ploidy, but also a requirement of Sun1 for the association of the centromere cluster with the centrosome. Live-cell imaging visualized the occurrence of mitotic defects, and demonstrated the requirement of microtubules for dynamic distance changes between centrosomes and nuclei. FRAP analysis revealed at least two populations of Sun1, with an immobile fraction associated with the centrosome, and a mobile fraction in the nuclear envelope.
Aspects of morphology control during the oxidative synthesis of electrically conducting polymers
(2009)
The formation of micro- and nanostructures during the oxidative polymerization of polypyrrole and polyaniline is investigated using different sulfonic acid dopants. Rod- or tube-like structures are found in polypyrrole as well as in polyaniline without addition of further compounds to the initial reaction mixture of monomer, dopant and oxidant. In these cases, always a crystalline precursor complex composed of a dopand molecule and the pure monomer (aniline) or a trimeric moiety (pyrrole) serves as in-situ template. In most cases the surface of the growing polymer is covered by secondary structures with much smaller sizes so that a hierarchical order of structures at different length scales results. Corresponding model considerations for the polymerization process are outlined. Additionally, unusual structures like platelets, frames, rings, or ribbons are observed in the polypyrrole synthesis in the presence of fluorosurfactants.
Previous studies that have examined the relationship between implicit and explicit motive measures have consistently found little variance overlap between both types of measures regardless of thematic content domain (i.e., power, achievement, affiliation). However, this independence may be artifactual because the primary means of measuring implicit motivescontent-coding stories people write about picture cuesare incommensurable with the primary means of measuring explicit motives: having individuals fill out self-report scales. To provide a better test of the presumed independence between both types of measures, we measured implicit motives with a Picture Story Exercise (PSE; McClelland, Koestner, Weinberger, 1989) and explicit motives with a cue- and response-matched questionnaire version of the PSE (PSE-Q) and a traditional measure of explicit motives, the Personality Research Form (PRF; Jackson, 1984) in 190 research participants. Correlations between the PSE and the PSE-Q were small and mostly nonsignificant, whereas the PSE- Q showed significant variance overlap with the PRF within and across thematic domains. We conclude that the independence postulate holds even when more commensurable measures of implicit and explicit motives are used.
The authors present organic photovoltaic (OPV) devices comprising a small molecule electron acceptor based on 2- vinyl-4,5-dicyanoimidazole (Vinazene (TM)) and a soluble poly(p-phenylenevinylene) derivative as the electron donor. A strong dependence of the fill factor (FF) and the external quantum efficiency [incident photons converted to electrons (IPCE)] on the heterojunction topology is observed. As-prepared blends provided relatively low FF and IPCE values of 26% and 4.5%, respectively, which are attributed to significant recombination of geminate pairs and free carriers in a highly intermixed blend morphology. Going to an all-solution processed bilayer device, the FF and IPCE dramatically increased to 43% and 27%, respectively. The FF increases further to 57% in devices comprising thermally deposited Vinazene layers where there is virtually no interpenetration at the donor/acceptor interface. This very high FF is comparable to values reported for OPV using fullerenes as the electron acceptor. Furthermore, the rather low electron affinity of Vinazene compound near 3.5 eV enabled a technologically important open circuit voltage (V-oc) of 1.0 V.
This article discusses how much the clean development mechanism (CDM) can contribute to the deployment of renewable energies (RE) in China. While there are at least two general barriers to utilizing CDM finance for RE deployment - namely high project costs and the proof of additionality - this article argues that an appropriate national regulation Can lead RE technologies to a stage of commercialisation at which CDM financing can become crucial. For an assessment of the current policy mix in place in China for the deployment of renewable energies, the article compares the national Chinese regulations for renewable energies and China's specific CDM rules for their impact: where do general and CDM-specific regulations for the promotion of renewable energies provide synergies, where does the policy- making on these two levels collide?
Investigating the dog genome we found 178965 introns with a moderate length of 200-1000 bp. A screening of these sequences against 23 different repeat libraries to find insertions of short interspersed elements (SINEs) detected 45276 SINEs. Virtually all of these SINEs (98%) belong to the tRNA-derived Can-SINE family. Can-SINEs arose about 55 million years ago before Carnivora split into two basal groups, the Caniformia (doglike carnivores) and the Feliformia (cat-like carnivores). Genome comparisons of dog and cat recovered 506 putatively informative SINE loci for caniformian phylogeny. In this study we show how to use such genome information of model organisms to research the phylogeny of related non-model species of interest. Investigating a dataset including representatives of all major caniformian lineages, we analysed 24 randomly chosen loci for 22 taxa. All loci were amplifiable and revealed 17 parsimony- informative SINE insertions. The screening for informative SINE insertions yields a large amount of sequence information, in particular of introns, which contain reliable phylogenetic information as well. A phylogenetic analysis of intron- and SINE sequence data provided a statistically robust phylogeny which is congruent with the absence/presence pattern of our SINE markers. This phylogeny strongly supports a sistergroup relationship of Musteloidea and Pinnipedia. Within Pinnipedia, we see strong support from bootstrapping and the presence of a SINE insertion for a sistergroup relationship of the walrus with the Otariidae.
We determine the metallicity distribution function (MDF) of the Galactic halo by means of a sample of 1638 metal-poor stars selected from the Hamburg/ESO objective-prism survey (HES). The sample was corrected for minor biases introduced by the strategy for spectroscopic follow-up observations of the metal-poor candidates, namely "best and brightest stars first". Comparison of the metallicities [Fe/H] of the stars determined from moderate-resolution (i.e., R similar to 2000) follow-up spectra with results derived from abundance analyses based on high-resolution spectra (i.e., R > 20 000) shows that the [Fe/H] estimates used for the determination of the halo MDF are accurate to within 0.3 dex, once highly C-rich stars are eliminated. We determined the selection function of the HES, which must be taken into account for a proper comparison between the HES MDF with MDFs of other stellar populations or those predicted by models of Galactic chemical evolution. The latter show a reasonable agreement with the overall shape of the HES MDF for [Fe/H] > -3.6, but only a model of Salvadori et al. (2007) with a critical metallicity for low-mass star formation of Z(cr) = 10(-3.4) Z(circle dot) reproduces the sharp drop at [Fe/H] similar to -3.6 present in the HES MDF. Although currently about ten stars at [Fe/H] < -3.6 are known, the evidence for the existence of a tail of the halo MDF extending to [Fe/H] similar to -5.5 is weak from the sample considered in this paper, because it only includes two stars [Fe/H] < -3.6. Therefore, a comparison with theoretical models has to await larger statistically complete and unbiased samples. A comparison of the MDF of Galactic globular clusters and of dSph satellites to the Galaxy shows qualitative agreement with the halo MDF, derived from the HES, once the selection function of the latter is included. However, statistical tests show that the differences between these are still highly significant.
Though orogen-parallel shortening and vertical extension have dominated the tectonic evolution of the central Andes, a significant kinematic shift from horizontal contraction to extension appears to have occurred within the high Puna-Altiplano Plateau, with the establishment of extension oblique to the orogen since late Miocene time. We present data from the southern margin of the Puna Plateau, NW Argentina, where new normal faults have been documented in the Fiambala, Punta Negra, and La Quebrada areas. The unifying characteristics of these areas are that young normal faults reactivate or crosscut older thrust and reverse faults. The relationship between the faults and the late Miocene- Pliocene Punaschotter conglomerate suggests that the extensional faulting must be younger than 3.5 to 7 Ma. Existing data are incomplete but indicate that similar horizontal extension has occurred in many regions throughout the Puna- Altiplano Plateau, while shortening continues along the plateau margins. Given the spatial and temporal distribution of this late Miocene to Pliocene kinematic shift, both lithospheric loss in the Puna Plateau and plateau-wide gravitational extensional spreading enhanced by slowing of plate convergence rate could be responsible. The young, disorganized, horizontal extension in the Andes today may be the precursor to more pronounced extension such as observed on the Tibetan Plateau since mid-Miocene time.
A confocal set-up for three-dimensional (3D) micro X-ray fluorescence (micro-XRF) was used at the mySpot beamline at BESSY II, which allows compositional depth profiling for various applications. We present results obtained with a confocal 3D micro-XRF set-up for chemical age dating using the U, Th and Pb concentrations of monazite within rock thin sections. The probing volume was determined to be approximately 21 x 21 x 24 mu m(3) for W-L alpha using an excitation energy of 19 keV. The relative detection limits particularly for Pb are below 10 ppm (for Counting times
Es werden Befunde aus einer prospektiven Laengsschnittstudie praesentiert, in der 321 Probanden im Alter von 8, 13, 18 und 25 Jahren untersucht werden konnten; ihre Dunkelfelddelinquenz wurde mit 18 und 25 Jahren erfasst. Wir suchten nach Assoziationen zur Delinquenzentwicklung und erwarteten Unterschiede zwischen auf das Jugendalter beschraenkter gegenueber ins fruehe Erwachsenenalter fortgesetzter sowie spaet, d.h. nach dem Alter von 18 Jahren, beginnender Delinquenz. Wir fanden gemeinsame Risikofaktoren und fuer die drei Verlaufstypen spezifische Risikokonstellationen, die eher im Jugendalter als in der Kindheit identifiziert wurden. Widrige familiaere Bedingungen, Entwicklungsverzoegerungen und psychische Stoerungen scheinen mit Delinquenz als eher persistentem Verhalten assoziiert.
The enantiomerically pure C-2-syrnmetrical hexa-1,5-diene-3,4-diol is selectively monopropargylated. The products undergo ring-closing enyne metathesis to give exclusively dihydropyrans as single stereoisomers. An unprotected hydroxy group is identified as the factor controlling the ring-size selectivity.
All stereoisomers of the natural product centrolobine are selectively synthesized, by starting from a common precursor. Key steps are an enantioselective allylation with enantiomerically pure allylsilanes, a tandem ring-closing metathesis-isomerization reaction, and a Heck reaction by using an arene diazonium salt. By choosing appropriate conditions for the final deprotection step, either the cis-configured centrolobines or their epimers are selectively obtained.
Recent evidence suggests that heterogeneity in the age at onset could explain the inconsistent findings of association studies relating the dopamine transporter (DAT1) gene with alcohol and nicotine consumption. The aim of this study was to examine interactions between two DAT1 polymorphisms and different initiation ages with regard to alcohol and tobacco consumption levels and dependence. Two hundred and ninety-one young adults (135 males, 156 females) participating in the Mannheim Study of Children at Risk were genotyped for the 40-bp variable number of tandem repeats (VNTR) and rs27072 polymorphisms of DAT1. Age at initiation was assessed at age 15 and 19 years. Information about current alcohol and tobacco consumption was obtained at age 19 years using self-report measures and structured interviews. Results suggest that age at onset of intensive consumption moderated the association of the DAT1 gene with early adult substance use and dependence, revealing a DAT1 effect only among individuals homozygous for the 10r allele of the 40-bp VNTR who had started daily smoking or being intoxicated early in life. Equally, carriers of the T allele of the rs27072 polymorphism reporting an early age at first intoxication showed higher current alcohol consumption at age 19 years. In contrast, no interaction between rs27072 and the age at first cigarette with regard to later smoking was observed. These findings provide evidence that the DAT1 gene interacts with an early heavy or regular drug exposure of the maturing adolescent brain to predict substance (ab)use in young adulthood. Further studies are required to confirm these findings.
In this paper we present the fabrication and characterization of polymer nanomembranes filled with magnetic nanoparticles and attached covalently to a periodic array of free-standing silicon walls, forming an array of micro- channels with the membrane as a cover. The width of a micro-channel of about 1.4 mu m sets a characteristic lateral size and the thickness of the polymer membrane ranges between 100 and 300 nm. The membrane is made of cross-linked hydrophilic polymers possessing a Young's modulus of only a few MPa. The presence of the magnetic particles within the membrane makes the film responsive to external magnetic fields. The mechanical and magnetic properties of the membrane are characterized by bulge tests and with atomic force microscopy.
In the recent past, recurrence quantification analysis (RQA) has gained an increasing interest in various research areas. The complexity measures the RQA provides have been useful in describing and analysing a broad range of data. It is known to be rather robust to noise and nonstationarities. Yet, one key question in empirical research concerns the confidence bounds of measured data. In the present Letter we suggest a method for estimating the confidence bounds of recurrence-based complexity measures. We study the applicability of the suggested method with model and real- life data.
Structural and thermochronologic studies of the western margin of the central Andean Plateau show changing styles of deformation through time that give insights into tectonic evolution. In southwest Peru, uplift of the plateau proceeded in several distinct phases. First, NW striking, NE dipping reverse faults accommodated uplift prior to similar to 14-16 Ma. Subsequent uplift of the plateau relative to the piedmont (between the plateau and the Pacific Ocean) occurred between similar to 14 and 2.2 Ma and was accommodated by NW striking, SW dipping normal faults and subparallel monoclinal folds. The youngest phase of uplift affected the piedmont region and the plateau margin as a coherent block. Although the uplift magnitude associated with phase 1 is unknown, phases 2 and 3 resulted in at least 2.4-3.0 km of uplift. Up to 1 km of this may have occurred during phase 3. Geodynamic processes occurring in both the continental interior and the subduction zone likely contributed to uplift.