On the role of soil moisture in the generation of heavy rainfall during the Oder flood event in July 1997

Soil moisture-atmosphere feedbacks play an important role in the regional climate over many regions worldwide, not only for the mean climate but also for extreme events. Several studies have shown that the extent and severity of droughts and heat waves can be significantly impacted by dry or wet soil moisture conditions. To date, the impact of soil moisture on heavy rainfall events has been less frequently investigated. Thus, we consider the role of soil moisture in the formation of heavy rainfall using the Oder flood event in July 1997 as an example. Here, we used the regional climate model CCLM as an uncoupled stand alone model and the coupled COSTRICE system, where CCLM is coupled with an ocean and a sea ice model over the Baltic and North Sea regions. The results from climate simulations over Europe show that the coupled model can capture the second phase (18-20 July) of heavy rainfall that led to the Oder flood, while the uncoupled model does not. Sensitivity experiments demonstrate that the better performance of the coupled model can be attributed to the simulated soil moisture conditions in July 1997 in Central Europe, which were wetter for the coupled model than for the uncoupled model. This finding indicates that the soil moisture preceding the event significantly impacted the generation of heavy rainfall in this second phase. The better simulation in the coupled model also implies the added value that the atmosphere-ocean coupling has on the simulation of this specific extreme event. As none of the model versions captured the first phase (4-8 July), despite the differences in soil moisture, it can be concluded that the importance of soil moisture for the generation of heavy rainfall events strongly depends on the event and the general circulation pattern associated with it

Characterization of the rainy season in Burkina Faso and it's representation by regional climate models

International audienceWest African monsoon is one of the most challenging climate components to model. Five regional climate models (RCMs) were run over the West African region with two lateral boundary conditions, ERA-Interim re-analysis and simulations from two general circulation models (GCMs). Two sets of daily rainfall data were generated from these boundary conditions. These simulated rainfall data are analyzed here in comparison to daily rainfall data collected over a network of ten synoptic stations in Burkina Faso from 1990 to 2004. The analyses are based on a description of the rainy season throughout a number of it's characteristics. It was found that the two sets of rainfall data produced with the two driving data present significant biases. The RCMs generally produce too frequent low rainfall values (between 0. 1 and 5 mm/day) and too high extreme rainfalls (more than twice the observed values). The high frequency of low rainfall events in the RCMs induces shorter dry spells at the rainfall thresholds of 0. 1-1 mm/day. Altogether, there are large disagreements between the models on the simulate season duration and the annual rainfall amounts but most striking are their differences in representing the distribution of rainfall intensity. It is remarkable that these conclusions are valid whether the RCMs are driven by re-analysis or GCMs. In none of the analyzed rainy season characteristics, a significant improvement of their representation can be found when the RCM is forced by the re-analysis, indicating that these deficiencies are intrinsic to the models. © 2011 The Author(s)

iSLIM: a comprehensive approach to mapping and characterizing gene regulatory networks

Mapping gene regulatory networks is a significant challenge in systems biology, yet only a few methods are currently capable of systems-level identification of transcription factors (TFs) that bind a specific regulatory element. We developed a microfluidic method for integrated systems-level interaction mapping of TF-DNA interactions, generating and interrogating an array of 423 full-length Drosophila TFs. With integrated systems-level interaction mapping, it is now possible to rapidly and quantitatively map gene regulatory networks of higher eukaryote

Evaluation of Arctic land snow cover characteristics, surface albedo and temperature during the transition seasons from regional climate model simulations and satellite data

This paper evaluates the simulated Arctic land snow cover duration, snow water equivalent, snow cover fraction, surface albedo and land surface temperature in the regional climate model HIRHAM5 during 2008-2010, compared with various satellite and reanalysis data and one further regional climate model (COSMO-CLM). HIRHAM5 shows a general agreement in the spatial patterns and annual course of these variables, although distinct biases for specific regions and months are obvious. The most prominent biases occur for east Siberian deciduous forest albedo, which is overestimated in the simulation for snow covered conditions in spring. This may be caused by the simplified albedo parameterization (e.g. non-consideration of different forest types and neglecting the effect of fallen leaves and branches on snow for deciduous tree forest). The land surface temperature biases mirror the albedo biases in their spatial and temporal structures. The snow cover fraction and albedo biases can explain the simulated land surface temperature bias of ca. -3 °C over the Siberian forest area in spring

Audition in vampire bats, Desmodus rotundus

1. Within the tonotopic organization of the inferior colliculus two frequency ranges are well represented: a frequency range within that of the echolocation signals from 50 to 100 kHz, and a frequency band below that of the echolocation sounds, from 10 to 35 kHz. The frequency range between these two bands, from about 40 to 50 kHz is distinctly underrepresented (Fig. 3B). 2. Units with BFs in the lower frequency range (10–25 kHz) were most sensitive with thresholds of -5 to -11 dB SPL, and units with BFs within the frequency range of the echolocation signals had minimal thresholds around 0 dB SPL (Fig. 1). 3. In the medial part of the rostral inferior colliculus units were encountered which preferentially or exclusively responded to noise stimuli. — Seven neurons were found which were only excited by human breathing noises and not by pure tones, frequency modulated signals or various noise bands. These neurons were considered as a subspeciality of the larger sample of noise-sensitive neurons. — The maximal auditory sensitivity in the frequency range below that of echolocation, and the conspicuous existence of noise and breathing-noise sensitive units in the inferior colliculus are discussed in context with the foraging behavior of vampire bats

THERMAL PHYSIOLOGY OF SCELOPORUS OLIVACEUS AND SCELOPORUS VARIABILIS IN SOUTH TEXAS

This study explores the thermal physiology of two sympatric lizard species, Sceloporus olivaceus (Texas spiny lizard) and Sceloporus variabilis (rose-bellied lizard), in South Texas. I document the metabolic rate and its temperature sensitivity, thermal limits, and performance at different temperatures to better understand the impact of rising temperatures and urbanization on these ectotherms, whose body temperature and, consequently, metabolic rate, activity level, and reproductive success depend on their thermal environment. We hypothesize that S. olivaceus will exhibit greater thermal resilience owing to its broader latitudinal range, variable habitat usage within Texas, and presumed more versatile thermoregulatory strategies. Scelorporus olivaceus\u27s higher voluntary thermal maximum and thermal stability across temperatures indicate a greater tolerance to elevated temperatures and a potential competitive advantage in warmer habitats that result from urbanization and climate change. Sceloporus variabilis appears to be less adapted to extremely warm temperatures, which may be why we do not see them on campus while they are common in adjacent forested habitats. Understanding these species\u27 thermal ecology is crucial for predicting their adaptability and guiding conservation efforts in rapidly changing environments

A Fast 3-Approximation for the Capacitated Tree Cover Problem with Edge Loads

The capacitated tree cover problem with edge loads is a variant of the tree cover problem, where we are given facility opening costs, edge costs and loads, as well as vertex loads. We try to find a tree cover of minimum cost such that the total edge and vertex load of each tree does not exceed a given bound. We present an (mlog n) time 3-approximation algorithm for this problem. This is achieved by starting with a certain LP formulation. We give a combinatorial algorithm that solves the LP optimally in time (mlog n). Then, we show that a linear time rounding and splitting technique leads to an integral solution that costs at most 3 times as much as the LP solution. Finally, we prove that the integrality gap of the LP is 3, which shows that we can not improve the rounding step in general

Effects of external nutrient sources and extreme weather events on the nutrient budget of a Southern European coastal lagoon

The seasonal and annual nitrogen (N), phosphorus (P), and carbon (C) budgets of the mesotidal Ria Formosa lagoon, southern Portugal, were estimated to reveal the main inputs and outputs, the seasonal patterns, and how they may influence the ecological functioning of the system. The effects of extreme weather events such as long-lasting strong winds causing upwelling and strong rainfall were assessed. External nutrient inputs were quantified; ocean exchange was assessed in 24-h sampling campaigns, and final calculations were made using a hydrodynamic model of the lagoon. Rain and stream inputs were the main freshwater sources to the lagoon. However, wastewater treatment plant and groundwater discharges dominated nutrient input, together accounting for 98, 96, and 88 % of total C, N, and P input, respectively. Organic matter and nutrients were continuously exported to the ocean. This pattern was reversed following extreme events, such as strong winds in early summer that caused upwelling and after a period of heavy rainfall in late autumn. A principal component analysis (PCA) revealed that ammonium and organic N and C exchange were positively associated with temperature as opposed to pH and nitrate. These variables reflected mostly the benthic lagoon metabolism, whereas particulate P exchange was correlated to Chl a, indicating that this was more related to phytoplankton dynamics. The increase of stochastic events, as expected in climate change scenarios, may have strong effects on the ecological functioning of coastal lagoons, altering the C and nutrient budgets.Portuguese Science and Technology Foundation (FCT) [POCI/MAR/58427/2004, PPCDT/MAR/58427/2004]; Portuguese Science and Technology Foundation (FCT

Interconnect Optimization in Chip Design

In this thesis, we take a closer look at the buffering problem. We review the literature on the buffering problem and examine how different algorithms try to solve it. We present an overview over the different aspects that are relevant for buffering, explain how they can be modelled and what decisions we made in modelling. Based on these considerations, we present a new problem formulation that captures more aspects and allows more degrees of freedom than all the previous algorithms and formulations. We present an (exponential time) algorithm that is able to solve this problem either approximately, or even optimally, with higher running time. Both variants depend on a slew accuracy function. We prove that the algorithm finds an optimum solution if it starts with a certain set of initial slews. Then, we show how to guess slews that allow us to find an optimum solution. In this way, we solve the inherent problem of including slew in buffering algorithms. Then, we demonstrate that the algorithm can be modified to include higher order delay models or increase the degrees of freedom at the cost of ignoring the slew. We also present multiple new speed up techniques. Among them are a data structure that efficiently maintains the labels in our algorithm, a construction of a sparse graph representing the routing space and buffering positions that retains helpful properties for finding good solutions and a practical (almost) feasible lower bound function. Then we develop as additional speedups a fast way to restrict the topology of solutions and present a new iterative clustering heuristic that is timing aware. It uses the Capacitated Tree Cover Problem with Edge Loads as a black box. We present a new 3-approximation algorithm for this problem that runs in O(mlog n) time. An underlying LP-relaxation can be solved optimally using a greedy algorithm, despite its exponential number of inequalities. We round this LP and apply a wellknown splitting technique to get to a feasible solution. In a final step, we prove that the integrality gap of our LP-relaxation is 3, which means that our analysis was optimal. Finally, we test our algorithm both in a benchmark setting and a practical setting. We show that we gain significant speedups by augmenting our algorithm with heuristic speedup techniques that do not lead to a notable loss in result quality. Then we examine how the fastest variants of our algorithm perform in a practical setting and see that it can give us significant improvements at a high runtime cost. Unfortunately, it is too slow to use it as a default tool in a design flow, but it can be used to optimize a few hard instances that otherwise would have to be optimized manually by a designer. Our algorithm allows us for the first time to benchmark existing buffering algorithms and heuristics. We can find out if solutions are good or how to improve them by comparing to our results. BonnRouteBuffer has been improved this way multiple times

Dependence properties of bivariate copula families

Motivated by recently investigated results on dependence measures and robust risk models, this paper provides an overview of dependence properties of many well known bivariate copula families, where the focus is on the Schur order for conditional distributions, which has the fundamental property that minimal elements characterize independence and maximal elements characterize perfect directed dependence. We give conditions on copulas that imply the Schur ordering of the associated conditional distribution functions. For extreme value copulas, we prove the equivalence of the lower orthant order, the Schur order for conditional distributions, and the pointwise order of the associated Pickands dependence functions. Further, we provide several tables and figures that list and illustrate various positive dependence and monotonicity properties of copula families, in particular from classes of Archimedean, extreme value, and elliptical copulas. Finally, for Chatterjee's rank correlation, which is consistent with respect to the Schur order for conditional distributions, we give some new closed-form formulas in terms of the parameter of the underlying copula family