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Electromagnetic induction (EMI) sensors using sufficiently low-frequency harmonic sources and sufficiently small loop separations operate in the low-induction-number (LIN) domain for a relatively wide range of background conductivity. These systems are used in diverse near-surface investigations including applications from soil sciences, hydrology, and archaeology. The special case of portable multiconfiguration EMI sensors operating at frequencies <= 20 kHz offers the possibility of using a fast linear deconvolution method to interpret multichannel data sets in three dimensions. Here, we have developed a fast 3D inversion/deconvolution method regularized with 3D smoothness constraints and formulated in the hybrid spectral-spatial domain. Compared with other linear approaches, the spectral-spatial domain formulation significantly reduces the computational cost of the processing and opens the door for real-time 3D interpretation of large data sets consisting of more than 100,000 data points. First, we test our proposed algorithm on synthetic data sets computed with the full Maxwell theory. Then, we apply our method to a real four-configuration EMI data set acquired to map the thickness of peat layers embedded in a sandy environment. For the synthetic and the field example, we compared our result with the result obtained using a standard point-by-point 1D nonlinear inversion approach. This comparison demonstrates that the proposed methodology provides superior lateral resolution compared with the 1D nonlinear inversion, at the same time significantly reducing the computational cost of the processing.
The phrase form and function was established in architecture and biology and refers to the idea that form and functionality are closely correlated, influence each other, and co-evolve. We suggest transferring this idea to hydrological systems to separate and analyze their two main characteristics: their form, which is equivalent to the spatial structure and static properties, and their function, equivalent to internal responses and hydrological behavior. While this approach is not particularly new to hydrological field research, we want to employ this concept to explicitly pursue the question of what information is most advantageous to understand a hydrological system. We applied this concept to subsurface flow within a hillslope, with a methodological focus on function: we conducted observations during a natural storm event and followed this with a hillslope-scale irrigation experiment. The results are used to infer hydrological processes of the monitored system. Based on these findings, the explanatory power and conclusiveness of the data are discussed. The measurements included basic hydrological monitoring methods, like piezometers, soil moisture, and discharge measurements. These were accompanied by isotope sampling and a novel application of 2-D time-lapse GPR (ground-penetrating radar). The main finding regarding the processes in the hillslope was that preferential flow paths were established quickly, despite unsaturated conditions. These flow paths also caused a detectable signal in the catchment response following a natural rainfall event, showing that these processes are relevant also at the catchment scale. Thus, we conclude that response observations (dynamics and patterns, i.e., indicators of function) were well suited to describing processes at the observational scale. Especially the use of 2-D time-lapse GPR measurements, providing detailed subsurface response patterns, as well as the combination of stream-centered and hillslope-centered approaches, allowed us to link processes and put them in a larger context. Transfer to other scales beyond observational scale and generalizations, however, rely on the knowledge of structures (form) and remain speculative. The complementary approach with a methodological focus on form (i.e., structure exploration) is presented and discussed in the companion paper by Jackisch et al. (2017).
The study deals with the identification and characterization of rapid subsurface flow structures through pedo- and geo-physical measurements and irrigation experiments at the point, plot and hillslope scale. Our investigation of flow-relevant structures and hydrological responses refers to the general interplay of form and function, respectively. To obtain a holistic picture of the subsurface, a large set of different laboratory, exploratory and experimental methods was used at the different scales. For exploration these methods included drilled soil core profiles, in situ measurements of infiltration capacity and saturated hydraulic conductivity, and laboratory analyses of soil water retention and saturated hydraulic conductivity. The irrigation experiments at the plot scale were monitored through a combination of dye tracer, salt tracer, soil moisture dynamics, and 3-D time-lapse ground penetrating radar (GPR) methods. At the hillslope scale the subsurface was explored by a 3-D GPR survey. A natural storm event and an irrigation experiment were monitored by a dense network of soil moisture observations and a cascade of 2-D time-lapse GPR "trenches". We show that the shift between activated and non-activated state of the flow paths is needed to distinguish structures from overall heterogeneity. Pedo-physical analyses of point-scale samples are the basis for sub-scale structure inference. At the plot and hillslope scale 3-D and 2-D time-lapse GPR applications are successfully employed as non-invasive means to image subsurface response patterns and to identify flow-relevant paths. Tracer recovery and soil water responses from irrigation experiments deliver a consistent estimate of response velocities. The combined observation of form and function under active conditions provides the means to localize and characterize the structures (this study) and the hydrological processes (companion study Angermann et al., 2017, this issue).
Influenza A virus matrix protein 1 (M1) is an essential component involved in the structural stability of the virus and in the budding of new virions from infected cells. A deeper understanding of the molecular basis of virion formation and the budding process is required in order to devise new therapeutic approaches. We performed a detailed investigation of the interaction between M1 and phosphatidylserine (PS) (i.e., its main binding target at the plasma membrane [PM]), as well as the distribution of PS itself, both in model membranes and in living cells. To this end, we used a combination of techniques, including Forster resonance energy transfer (FRET), confocal microscopy imaging, raster image correlation spectroscopy, and number and brightness (N&B) analysis. Our results show that PS can cluster in segregated regions in the plane of the lipid bilayer, both in model bilayers constituted of PS and phosphatidylcholine and in living cells. The viral protein M1 interacts specifically with PS-enriched domains, and such interaction in turn affects its oligomerization process. Furthermore, M1 can stabilize PS domains, as observed in model membranes. For living cells, the presence of PS clusters is suggested by N&B experiments monitoring the clustering of the PS sensor lactadherin. Also, colocalization between M1 and a fluorescent PS probe suggest that, in infected cells, the matrix protein can specifically bind to the regions of PM in which PS is clustered. Taken together, our observations provide novel evidence regarding the role of PS-rich domains in tuning M1-lipid and M1-M1 interactions at the PM of infected cells. IMPORTANCE Influenza virus particles assemble at the plasma membranes (PM) of infected cells. This process is orchestrated by the matrix protein M1, which interacts with membrane lipids while binding to the other proteins and genetic material of the virus. Despite its importance, the initial step in virus assembly (i.e., M1-lipid interaction) is still not well understood. In this work, we show that phosphatidylserine can form lipid domains in physical models of the inner leaflet of the PM. Furthermore, the spatial organization of PS in the plane of the bilayer modulates M1-M1 interactions. Finally, we show that PS domains appear to be present in the PM of living cells and that M1 seems to display a high affinity for them.
The African Humid Period (AHP) between similar to 15 and 5.5 cal. kyr BP caused major environmental change in East Africa, including filling of the Suguta Valley in the northern Kenya Rift with an extensive (similar to 2150 km(2)), deep (similar to 300 m) lake. Interfingering fluvio-lacustrine deposits of the Baragoi paleo-delta provide insights into the lake-level history and how erosion rates changed during this time, as revealed by delta-volume estimates and the concentration of cosmogenic Be-10 in fluvial sand. Erosion rates derived from delta-volume estimates range from 0.019 to 0.03 mm yr(-1). Be-10-derived paleo-erosion rates at similar to 11.8 cal. kyr BP ranged from 0.035 to 0.086 mm yr(-1), and were 2.7 to 6.6 times faster than at present. In contrast, at similar to 8.7 cal. kyr BP, erosion rates were only 1.8 times faster than at present. Because Be-10-derived erosion rates integrate over several millennia; we modeled the erosion-rate history that best explains the 10Be data using established non-linear equations that describe in situ cosmogenic isotope production and decay. Two models with different temporal constraints (15-6.7 and 12-6.7 kyr) suggest erosion rates that were 25 to 300 times higher than the initial erosion rate (pre-delta formation). That pulse of high erosion rates was short (similar to 4 kyr or less) and must have been followed by a rapid decrease in rates while climate remained humid to reach the modern Be-10-based erosion rate of,similar to 0.013 mm yr(-1). Our simulations also flag the two highest Be-10-derived erosion rates at 11.8 kyr BP related to nonuniform catchment erosion. These changes in erosion rates and processes during the AHP may reflect a strong increase in precipitation, runoff, and erosivity at the arid-to-humid transition either at 15 or similar to 12 cal. kyr BP, before the landscape stabilized again, possibly due to increased soil production and denser vegetation.
Near-surface geophysical techniques are extensively used in a variety of engineering, environmental, geologic, and hydrologic applications. While many of these applications ask for detailed, quantitative models of selected material properties, geophysical data are increasingly used to estimate such target properties. Typically, this estimation procedure relies on a two-step workflow including (1) the inversion of geophysical data and (2) the petrophysical translation of the inverted parameter models into the target properties. Standard deterministic implementations of such a quantitative interpretation result in a single best-estimate model, often without considering and propagating the uncertainties related to the two steps. We address this problem by using a rather novel, particle-swarm-based global joint strategy for data inversion and by implementing Monte Carlo procedures for petrophysical property estimation. We apply our proposed workflow to crosshole ground-penetrating radar, P-, and S-wave data sets collected at a well-constrained test site for a detailed geotechnical characterization of unconsolidated sands. For joint traveltime inversion, the chosen global approach results in ensembles of acceptable velocity models, which are analyzed to appraise inversion-related uncertainties. Subsequently, the entire ensembles of inverted velocity models are considered to estimate selected petrophysical properties including porosity, bulk density, and elastic moduli via well-established petrophysical relations implemented in a Monte Carlo framework. Our results illustrate the potential benefit of such an advanced interpretation strategy; i.e., the proposed workflow allows to study how uncertainties propagate into the finally estimated property models, while concurrently we are able to study the impact of uncertainties in the used petrophysical relations (e.g., the influence of uncertain, user-specified parameters). We conclude that such statistical approaches for the quantitative interpretation of geophysical data can be easily extended and adapted to other applications and geophysical methods and might be an important step toward increasing the popularity and acceptance of geophysical tools in engineering practice.
Mietpreisbremse
(2017)
Der Zugang der Bevölkerung zu Wohnraum und die Bezahlbarkeit des Wohnens sind seit jeher Kernthemen der Sozialen Marktwirtschaft. Für den Gesetzgeber ist es nicht zuletzt angesichts von rund 23 Millionen Mieterhaushalten in Deutschland politisch attraktiv, mittels gesetzlicher Beschränkungen Einfluss auf die Mietpreisentwicklung zu nehmen. Das Werk zeigt die ökonomischen Auswirkungen derartiger Mietpreisbegrenzungen auf, untersucht ihre regulatorischen und privatrechtlichen Implikationen und arbeitet die Grenzen für eine verfassungskonforme Ausgestaltung heraus. Dabei nimmt der Autor auch zur Diskussion um die sog. Materialisierung des Privatrechts Stellung und entwickelt einen eigenen Ansatz, wie sich unter privatrechtlichen Gesichtspunkten Einschränkungen der Vertragsfreiheit rechtfertigen lassen. Die Arbeit schließt mit einer umfassenden Bewertung der im Jahr 2015 eingeführten Mietpreisbremse, in deren Rahmen insbesondere die Verfassungsmäßigkeit der Mietpreisbremse untersucht wird.
Ausgezeichnet mit dem Fakultätspreis der Universität Potsdam.
Die Rechtsgrundlagen des grenzüberschreitenden Kooperationsrechts zwischen Gebietskörperschaften
(2017)
Durch den Siegeszug der interkommunalen Zusammenarbeit und ihrer rechtlichen Grundlagen in den letzten Jahrzehnten wurde das Kooperationsrecht zwischen Gebietskörperschaften innerhalb von nationalen oder regionalen Rechtsordnungen umfassend erforscht. Die Frage nach der Anwendung dieses Rechts in einem grenzüberschreitenden Zusammenhang fand hingegen kaum Beachtung. Diese Arbeit zielt deshalb auf eine systematische Einordnung der Rechtsquellen der nationalen und europäischen Rechtsordnungen ab, die für die grenzüberschreitende Zusammenarbeit zwischen Gebietskörperschaften Anwendung finden.
Mit Inkrafttreten der NFA 2008 hat die Schweiz ihren Finanzausgleich umfassend reformiert und erstmals auch einen direkt umverteilenden Ausgleich zwischen den Kantonen geschaffen. Diese Reform blieb auf deutscher Seite weitgehend unbeachtet. Der Autor vergleicht zunächst die finanzverfassungsrechtlichen Grundstrukturen in beiden Ländern und erläutert das bestehende und das ab 2020 geltende deutsche System. Dem folgt eine umfassende Analyse des sekundären Finanzausgleichs in der Schweiz, sog. Finanzausgleich im engeren Sinn, mit ausführlicher Darstellung des Ressourcenausgleichs sowie des geografisch-topografischen und soziodemografischen Lastenausgleichs. Im Anschluss werden nach Problemschwerpunkten gegliedert Reformoptionen für Deutschland aufgezeigt. Der Autor plädiert insbesondere für einen nach Schweizer Vorbild gestalteten indikatorbasierten Lastenausgleich, um dem verfassungsrechtlichen Benennungs- und Begründungsgebot bei Sonderlasten besser gerecht zu werden.
Durch Art. 20 Abs. 1 des Grundgesetzes wird die Bundesrepublik Deutschland als demokratischer und sozialer Bundesstaat insbesondere dem Föderalismus verpflichtet. Er ist neben der Demokratie eine der Säulen unseres Staatswesens. Im Bewusstsein dieser Grundentscheidung unserer Verfassung fällt mit Art. 115f Abs. 1 Nr. 2 GG eine Vorschrift auf, die hiervon im Verteidigungsfall eine weitreichende Ausnahme zu ermöglichen scheint. Die Bundesregierung soll dann unter bestimmten Voraussetzungen außer der Bundesverwaltung auch den Landesregierungen und Landesbehörden Weisungen erteilen können. Es stellt sich in Anbetracht eines solchen Ausnahmerechts die Frage, wie sich dieses Weisungsrecht der Bundesregierung in unser Rechtssystem einfügt.
Der Autor nähert sich dieser Frage zunächst über die geschichtlichen Hintergründe, die zur Einfügung der Vorschrift geführt haben. Er geht detailliert auf die Voraussetzungen dieses Weisungsrechts der Bundesregierung ein und stellt es in seinen systematischen Zusammenhang. Neben einer Darstellung des Weisungsbegriffs als Möglichkeit der Einflussnahme auf die Bundesverwaltung und die Länder, werden auch die damit umschriebenen Weisungsadressaten näher untersucht. Auch den Fragen, welchen Gegenstand Weisungen nach dieser Vorschrift haben können, wie sie zu erlassen sind und welche Wirkungen sich aus ihnen ergeben, wird in der Untersuchung detailreich nachgegangen. Daneben behandelt der Autor die sich daraus ergebenden Anschlussfragen, welcher Rechtsschutz gegen derartige Weisungen besteht, wer damit verbundene Aufgaben zu finanzieren hat und wer für eventuelle Schäden zu haften hat. Das Werk schließt mit einer Erörterung, ob es sich bei dieser Vorschrift um eine verfassungswidrige Verfassungsnorm handelt, und einem Blick auf internationale Vorschriften, die Einfluss auf das Weisungsrecht nehmen könnten.
Fluthilfe 2013
(2017)
Die Abhandlung „Fluthilfe 2013 – Finanzierung der Hochwassernachsorge“ erläutert im ersten Hauptteil die verfassungsrechtlichen Probleme im Zusammenhang mit der Errichtung von staatlichen Sondervermögen, da der Bund solche Fonds jeweils nach den Hochwasserkatastrophen der Jahre 2002 und 2013 errichtete und mit einem Milliardenbudget ausstattete. Der zweite Hauptteil überprüft am Beispiel des Sondervermögens Aufbauhilfe 2013 die Kompetenzen von Bund und Ländern bei der Milderung und Beseitigung von öffentlichen und privaten Flutschäden. Daneben finden in der vorliegenden Abhandlung europarechtliche Bezüge, die Hochwasserprävention und -vorsorge sowie die Rechte und Pflichten von Staat und Bürgern im Falle einer Flutkatastrophe Berücksichtigung. Die Arbeit endet mit konkreten Änderungsvorschlägen zur verfassungsrechtlichen Kompetenzverteilung für den Bereich Hochwassernachsorge.
§ 4 Kommunalrecht
(2017)
We give a new and very short proof of a theorem of Greiner asserting that a positive and contractive -semigroup on an -space is strongly convergent in case it has a strictly positive fixed point and contains an integral operator. Our proof is a streamlined version of a much more general approach to the asymptotic theory of positive semigroups developed recently by the authors. Under the assumptions of Greiner's theorem, this approach becomes particularly elegant and simple. We also give an outlook on several generalisations of this result.
The concept of a Global Monsoon (GM) has been proposed based on modern precipitation observations, but its application over a wide range of temporal scales is still under debate. Here, we present a synthesis of 268 continental paleo-moisture records collected from monsoonal systems in the Eastern Hemisphere, including the East Asian Monsoon (EAsM), the Indian Monsoon (IM), the East African Monsoon (EAfM), and the Australian Monsoon (AuM) covering the last 18,000 years. The overall pattern of late Glacial to Holocene moisture change is consistent with those inferred from ice cores and marine records. With respect to the last 10,000 years (10 ka), i.e. a period that has high spatial coverage, a Fuzzy c-Means clustering analysis of the moisture index records together with "Xie-Beni" index reveals four clusters of our data set. The paleoclimatic meaning of each cluster is interpreted considering the temporal evolution and spatial distribution patterns. The major trend in the tropical AuM, EAfM, and IM regions is a gradual decrease in moisture conditions since the early Holocene. Moisture changes in the EAsM regions show maximum index values between 8 and 6 ka. However, records located in nearby subtropical areas, i.e. in regions not influenced by the intertropical convergence zone, show an opposite trend compared to the tropical monsoon regions (AuM, EAfM and IM), i.e. a gradual increase. Analyses of modern meteorological data reveal the same spatial patterns as in the paleoclimate records such that, in times of overall monsoon strengthening, lower precipitation rates are observed in the nearby subtropical areas. We explain this pattern as the effect of a strong monsoon circulation suppressing air uplift in nearby subtropical areas, and hence hindering precipitation. By analogy to the modern system, this would mean that during the early Holocene strong monsoon period, the intensified ascending airflows within the monsoon domains led to relatively weaker ascending or even descending airflows in the adjacent subtropical regions, resulting in a precipitation deficit compared to the late Holocene. Our conceptual model therefore integrates regionally contrasting moisture changes into the Global Monsoon hypothesis. (C) 2017 Elsevier Ltd. All rights reserved.
Heterostyly is a fascinating adaptation to promote outbreeding and a classical paradigm of botany. In the most common type of heterostyly, plants either form flowers with long styles and short stamens, or short styles and long stamens. This reciprocal organ positioning reduces pollen wastage and promotes cross-pollination, thus increasing male fitness. In addition, in many heterostylous species selfing and the generation of unfit progeny due to inbreeding depression is limited by a self-incompatibility system, thus promoting female fitness. The two floral forms are genetically determined by the S locus as a complex supergene, namely a chromosomal region containing several individual genes that control the different traits, such as style or stamen length, and are held together by very tight linkage due to suppressed recombination. Recent molecular-genetic studies in several systems, including Turnera, Fagopyrum, Linum, and Primula have begun to identify and characterize the causal heterostyly genes residing at the S locus. An emerging theme from several families is that the dominant S haplotype represents a hemizygous region not present on the recessive s haplotype. This provides an explanation for the suppressed recombination and suggests a scenario for the chromosomal evolution of the S locus. In this review, we discuss the results from recent molecular-genetic analyses in light of the classical models on the genetics and evolution of heterostyly.