Refine
Year of publication
- 2011 (1133) (remove)
Document Type
- Article (823)
- Doctoral Thesis (139)
- Postprint (40)
- Review (40)
- Monograph/Edited Volume (32)
- Conference Proceeding (26)
- Other (12)
- Preprint (7)
- Part of a Book (6)
- Master's Thesis (3)
Language
- English (1133) (remove)
Keywords
- climate change (8)
- X-rays: stars (7)
- Holocene (6)
- Tibetan Plateau (6)
- NMR (5)
- gamma rays: general (5)
- stars: massive (5)
- Dictyostelium (4)
- Eye movements (4)
- Photosynthesis (4)
Institute
- Institut für Biochemie und Biologie (230)
- Institut für Physik und Astronomie (178)
- Institut für Chemie (159)
- Institut für Geowissenschaften (134)
- Department Psychologie (55)
- Institut für Informatik und Computational Science (46)
- Institut für Ernährungswissenschaft (42)
- Institut für Mathematik (37)
- Department Linguistik (32)
- Institut für Anglistik und Amerikanistik (32)
On utilise de plus en plus les tests de verification pour confirmer l'atteinte du consommation d'oxygene maximale (VO(2 max)). Toutefois, le moment et les methodes d'evaluation varient d'un groupe de travail a l'autre. Les objectifs de cette etude sont de constater si on peut administrer un test de verification apres un test d'effort progressif ou s'il est preferable de le faire une autre journee et si on peut determiner le VO(2 max) tout de meme lors de la premiere seance chez des sujets ne repondant pas au critere de verification. Quarante sujets (age, 24 +/- 4 ans; VO(2 max), 50 +/- 7 mL center dot min(-1)center dot kg(-1)) participent a un test d'effort progressif sur tapis roulant et, 10 min plus tard, a un test de verification (VerifDay1) a 110 % de la velocite maximale (v(max)). Le critere de verification est un VO(2) de pointe au VerifDay1 < 5,5 % a la valeur retenue au test d'effort progressif. Les sujets ne repondant pas au critere de verification passent un autre test de verification, mais a 115 % du VerifDay1', et ce, 10 min plus tard pour confirmer le VO(2) de pointe du VerifDay1 en tant que VO(2 max). Tous les autres sujets repassent le VerifDay1 a un jour different (VerifDay2). Six sujets sur quarante ne repondent pas au critere de verification. Chez quatre d'entre eux, on confirme l'atteinte du VO(2 max) au VerifDay1'. Le VO(2) de pointe au VerifDay1 est equivalent a celui du VerifDay2 (3722 +/- 991 mL center dot min(-1) comparativement a 3752 +/- 995 mL center dot min(-1), p = 0,56), mais le temps jusqu'a l'epuisement est significativement plus long au VerifDay2 (2:06 +/- 0:22 min:s comparativement a 2:42 +/- 0:38 min:s, p < 0,001, n = 34). Le VO(2) de pointe obtenu au test de verification ne semble pas conditionne par un test d'effort progressif maximal prealable. On peut donc realiser le test d'effort progressif et le test de verification lors de la meme seance d'evaluation. Chez presque tous les individus ne repondant pas au critere de verification, on peut determiner le VO(2 max) au moyen d'un autre test de verification plus intense.
The growth of plant organs is under genetic control. Work in model species has identified a considerable number of genes that regulate different aspects of organ growth. This has led to an increasingly detailed knowledge about how the basic cellular processes underlying organ growth are controlled, and which factors determine when proliferation gives way to expansion, with this transition emerging as a critical decision point during primordium growth. Progress has been made in elucidating the genetic basis of allometric growth and the role of tissue polarity in shaping organs. We are also beginning to understand how the mechanisms that determine organ identity influence local growth behaviour to generate organs with characteristic sizes and shapes. Lastly, growth needs to be coordinated at several levels, for example between different cell layers and different regions within one organ, and the genetic basis for such coordination is being elucidated. However, despite these impressive advances, a number of basic questions are still not fully answered, for example, whether and how a growing primordium keeps track of its size. Answering these questions will likely depend on including additional approaches that are gaining in power and popularity, such as combined live imaging and modelling.
We implemented an experimental scheme for ultrafast x-ray diffraction at storage rings based on a laser-driven Bragg-switch that shortens the x-ray pulses emitted from an undulator. The increased time-resolution is demonstrated by observing changes of intensity, position and width of the diffraction peaks of a La(0.7)Sr(0.3)MnO(3)/SrTiO(3) superlattice sample after optical excitation, i.e., by quantitatively measuring the propagation of an expansion wave through the sample. These experimental transients with timescales of 35 to 60 ps evidence a reduction of the x-ray pulse duration by a factor of two.
The change from outbreeding to selfing is one of the most frequent evolutionary transitions in flowering plants. It is often accompanied by characteristic morphological and functional changes to the flowers (the selfing syndrome), including reduced flower size and opening. Little is known about the developmental and genetic basis of the selfing syndrome, as well as its adaptive significance. Here, we address these issues using the two closely related species Capsella grandiflora (the ancestral outbreeder) and red shepherd's purse (Capsella rubella, the derived selfer). In C. rubella, petal size has been decreased by shortening the period of proliferative growth. Using interspecific recombinant inbred lines, we show that differences in petal size and flower opening between the two species each have a complex genetic basis involving allelic differences at multiple loci. An intraspecific cross within C. rubella suggests that flower size and opening have been decreased in the C. rubella lineage before its extensive geographical spread. Lastly, by generating plants that likely resemble the earliest ancestors of the C. rubella lineage, we provide evidence that evolution of the selfing syndrome was at least partly driven by selection for efficient self-pollination. Thus, our studies pave the way for a molecular dissection of selfing-syndrome evolution.
Salt diapirs are common features of sedimentary basins. If close to the surface, they can bear a significant hazard due to possible dissolution sinkholes, karst formation and collapse dolines or their influence on ground water chemistry. We investigate the potential of ambient vibration techniques to map the 3-D roof morphology of shallow salt diapirs. Horizontal-to-vertical (H/V) spectral peaks are derived at more than 900 positions above a shallow diapir beneath the city area of Hamburg, Germany, and are used to infer the depth of the first strong impedance contrast. In addition, 15 small-scale array measurements are conducted at different positions in order to compute frequency-dependent phase velocities of Rayleigh waves between 0.5 and 25 Hz. The dispersion curves are inverted together with the H/V peak frequency to obtain shear-wave velocity profiles. Additionally, we compare the morphology derived from H/V and array measurements to borehole lithology and a gravity-based 3-D model of the salt diapir. Both methods give consistent results in agreement with major features indicated by the independent data. An important result is that H/V and array measurements are better suited to identify weathered gypsum caprocks or gypsum floaters, while gravity-derived models better sample the interface between sediments and homogeneous salt. We further investigate qualitatively the influence of the 3-D subsurface topography of the salt diapir on the validity of local 1-D inversion results from ambient vibration dispersion curve inversion.
1-Oxo-1,3-dithiolane (4) and its cis- andtrans-2-methyl (5,6), -4-methyl (7,8) and -5-methyl (9,10) derivatives were prepared by oxidizing the corresponding 1,3-dithiolanes (1-3) with NaIO4 in water. The oxides were purified and their isomers separated using thin layer chromatography. The structural characterization was carried out with 1H and 13C NMR spectroscopy and molecular modelling. The sulfoxides 4-6 and 8-10 attain two S(1) type envelopes (sometimes slightly distorted) the S=Oax envelope greatly dominating. Cis-4-methyl-1-oxo-1,3-dithiolane is a special case exhibiting both two closely related S=Oax (30 and 27%) as well as S=Oeq (21 and 22%) forms [S(1) and C(4) envelopes, respectively]. The relative energies of these conformations, the values of 1H-1H coupling constants and 1H and 13C chemical shifts were estimated by computational methods and they support well the conclusions based on the experimental data.