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Search Results: 1 - 10 of 2409 matches for " Davin Chia "
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Colored Bin Packing
Hamza Alsarhan,Davin Chia,Ananya Christman,Shannia Fu,Tony Jin
Computer Science , 2015,
Abstract: We study the Colored Bin Packing Problem: we are given a set of items where each item has a weight and color. We must pack the items in bins of uniform capacity such that no two items of the same color may be adjacent within in a bin. The goal is to perform this packing using the fewest number of bins. We consider a version of the problem where reordering is allowed. We first consider the zero-weight and unit weight versions of this problem, i.e. where the items have weight zero and one, respectively. We present linear time optimal algorithms for both versions.
Bin Packing with Multiple Colors
Hamza Alsarhan,Davin Chia,Ananya Christman,Shannia Fu,Yanfeng Jin
Computer Science , 2015,
Abstract: In the Colored Bin Packing problem a set of items with varying weights and colors must be packed into bins of uniform weight limit such that no two items of the same color may be packed adjacently within a bin. We solve this problem for the case where there are two or more colors when the items have zero weight and when the items have unit weight. Our algorithms are optimal and run in linear time. Since our algorithms apply for two or more colors, they demonstrate that the problem does not get harder as the number of colors increases. We also provide closed-form expressions for the optimal number of bins.
Neural Mechanisms of Impaired Fear Inhibition in Posttraumatic Stress Disorder
Tanja Jovanovic,Seth Davin Norrholm
Frontiers in Behavioral Neuroscience , 2011, DOI: 10.3389/fnbeh.2011.00044
Abstract: Posttraumatic stress disorder (PTSD) can develop in some individuals who are exposed to an event that causes extreme fear, horror, or helplessness (APA, 1994). PTSD is a complex and heterogeneous disorder, which is often co-morbid with depression, substance abuse, and anxiety disorders such as panic or social phobia. Given this complexity, progress in the field can be greatly enhanced by focusing on phenotypes that are more proximal to the neurobiology of the disorder. Such neurobiological intermediate phenotypes can provide investigative tools to increase our understanding of the roots of the disorder and develop better prevention or intervention programs. In the present paper, we argue that the inhibition of fear responses is an intermediate phenotype that is related to both the neurocircuitry associated with the disorder, and is linked to its clinical symptoms. An advantage of focusing on fear inhibition is that the neurobiology of fear has been well investigated in animal models providing the necessary groundwork in understanding alterations. Furthermore, because many paradigms can be tested across species, fear inhibition is an ideal translational tool. Here we review both the behavioral tests and measures of fear inhibition and the related neurocircuitry in neuroimaging studies with both healthy and clinical samples.
A Performance-Based Framework for Bridge Preservation Based on Damage-Integrated System-Level Behavior
Amir Gheitasi,Davin K. Harris
Mathematics , 2014,
Abstract: The safety and condition of transportation infrastructure has been at the forefront of national debates in recent times due to catastrophic bridge failures, but the issue has been a longstanding challenge for transportation agencies for many years as resources continue to diminish. The performance of this infrastructure has a direct influence on the lives of most of citizens in developed regions by providing a critical lifeline between communities and the transportation of goods and services, and as a critical component of the transportation network, bridges have received a lot of attention regarding condition assessment and maintenance practices. Despite successful implementation of advanced evaluation techniques, what is still lacking is a fundamental understanding of the system behavior in the presence of deteriorating conditions that can be used for preservation decision-making. This paper aims to present a performance-based framework that can be used to characterize the behavior of in-service bridge superstructures. In order to measure the bridge system performance with deteriorating conditions, system-level behavior of a representative composite steel girder bridge, degraded with three common damage scenarios was investigated in this study. Results obtained from validated numerical analysis demonstrated significant impact of integrated damage mechanisms on the ultimate capacity, redundancy and system ductility of the simulated bridge superstructure. It is expected that the proposed framework for evaluating system behavior will provide a first step for establishing a critical linkage between design, maintenance, and rehabilitation of highway bridges, which are uncoupled in current infrastructure decision-making processes.
Nephrotic Syndrome in Children: From Bench to Treatment
J.-C. Davin,N. W. Rutjes
International Journal of Nephrology , 2011, DOI: 10.4061/2011/372304
Abstract: Idiopathic nephrotic syndrome (INS) is the most frequent form of NS in children. INS is defined by the association of the clinical features of NS with renal biopsy findings of minimal changes, focal segmental glomerulosclerosis (FSGS), or mesangial proliferation (MP) on light microscopy and effacement of foot processes on electron microscopy. Actually the podocyte has become the favourite candidate for constituting the main part of the glomerular filtration barrier. Most cases are steroid sensitive (SSINS). Fifty percents of the latter recur frequently and necessitate a prevention of relapses by nonsteroid drugs. On the contrary to SSINS, steroid resistant nephrotic syndrome (SRINS) leads often to end-stage renal failure. Thirty to forty percents of the latter are associated with mutations of genes coding for podocyte proteins. The rest is due to one or several different circulating factors. New strategies are in development to antagonize the effect of the latter. 1. Introduction Nephrotic syndrome (NS) is an illness consisting in leakage of proteins in urine, resulting in life threatening conditions due hypovolemia, hypercoagulation, and infection. The annual incidence of NS in children in the USA and in Europe has been estimated to be 1–7 per 100,000 children, with a cumulative prevalence of 16 per 100,000 children [1–3]. Nephrotic syndrome in children can be classified according to 3 three groups [3]: secondary, congenital and infantile, and idiopathic. Secondary nephrotic syndrome is defined as nephrotic syndrome associated with well-defined diseases that are inflammatory (e.g., lupus nephritis, acute postinfectious glomerulonephritis, IgA nephropathy, Henoch-Sch?nlein purpura, etc.) or not (e.g., Alport syndrome, focal sclerosis due to reduced nephronic mass resulting from renal scarring, etc.). Congenital and infantile NSs are occurring before the age of one year and are mostly associated with infections (e.g., syphilis, toxoplasmosis, etc.) or with mutations of genes coding for podocytes proteins and are steroid resistant. Idiopathic nephrotic syndrome (INS) is the most frequent form of NS in children representing more than 90 percent of cases between 1 and 10 years of age and 50 percent after 10 years of age [1]. INS is defined by the association of the clinical features of NS with renal biopsy findings of diffuse foot process effacement on electron microscopy and minimal changes (called minimal change disease (MCD)), focal segmental glomerulosclerosis (FSGS), or diffuse mesangial proliferation (DMP) on light microscopy [4]. Most patients have
libcov: A C++ bioinformatic library to manipulate protein structures, sequence alignments and phylogeny
Davin Butt, Andrew J Roger, Christian Blouin
BMC Bioinformatics , 2005, DOI: 10.1186/1471-2105-6-138
Abstract: The bioinformatics library libcov is a collection of C++ classes that provides a high and low-level interface to maximum likelihood phylogenetics, sequence analysis and a data structure for structural biological methods. libcov can be used to compute likelihoods, search tree topologies, estimate site rates, cluster sequences, manipulate tree structures and compare phylogenies for a broad selection of applications.Using this library, it is possible to rapidly prototype applications that use the sophistication of phylogenetic likelihoods without getting involved in a major software engineering project. libcov is thus a potentially valuable building block to develop in-house methodologies in the field of protein phylogenetics.With the development of genomics, research in biology and systems biology is becoming increasingly data-driven. The feedback between available data and hypotheses has accelerated the pace at which innovative ideas are generated. Life scientists are in a position to design novel methodologies but do not necessarily have the in-house skills to produce software implementations. Simple methods, made of complex building blocks such as maximum likelihood calculations, require major software development projects before they can be prototyped. The use of libraries can help to rapidly prototype software implementations.We present libcov, an object-oriented library to perform phylogenetic inference and the manipulation of protein sequences and structures. The library is written in C++, is compliant with the GNU standards and packaged as a dynamic library that can be installed on most Unix distributions (including MacOS X).There are other bioinformatic libraries available, many of which overlap with libcov in their functionalities. The PAL library, for example, [1] is a Java implementation which offers a versatile object set for nucleotide and protein phylogeny. More generally, interested readers can visit the Open Bioinformatics Foundation [2] that links to
Preface ''Nitrogen & Global Change''
E. L. Davin ,S. I. Seneviratne
Biogeosciences (BG) & Discussions (BGD) , 2012,
Abstract: The influence of land processes and in particular of diffuse/direct radiation partitioning on surface fluxes and associated regional-scale climate feedbacks is investigated using ERA-40 driven simulations over Europe performed with the COSMO-CLM2 Regional Climate Model (RCM). Two alternative Land Surface Models (LSMs), a 2nd generation LSM (TERRA_ML) and a more advanced 3rd generation LSM (Community Land Model version 3.5), and two versions of the atmospheric component are tested, as well as a revised coupling procedure allowing for variations in diffuse/direct light partitioning at the surface, and their accounting by the land surface component. Overall, the RCM performance for various variables (e.g., surface fluxes, temperature and precipitation) is improved when using the more advanced 3rd generation LSM. These improvements are of the same order of magnitude as those arising from a new version of the atmospheric component, demonstrating the benefit of using a realistic representation of land surface processes for regional climate simulations. Taking into account the variability in diffuse/direct light partitioning at the surface further improves the model performance in terms of summer temperature variability at the monthly and daily time scales. Comparisons with observations show that the RCM realistically captures temporal variations in diffuse/direct light partitioning as well as the evapotranspiration sensitivity to these variations. Our results suggest that a modest but consistent fraction (up to 3 %) of the overall variability in summer temperature can be explained by variations in the diffuse to direct ratio.
Role of land surface processes and diffuse/direct radiation partitioning in simulating the European climate
E. L. Davin,S. I. Seneviratne
Biogeosciences Discussions , 2011, DOI: 10.5194/bgd-8-11601-2011
Abstract: The influence of land processes and in particular of diffuse/direct radiation partitioning on surface fluxes and associated regional-scale climate feedbacks is investigated. ERA-40 driven simulations over Europe are performed using the COSMO-CLM2 Regional Climate Model (RCM). Two alternative Land Surface Models (LSMs), a 2nd generation LSM (TERRA_ML) and a more advanced 3rd generation LSM (Community Land Model version 3.5), and two versions of the atmospheric component are tested, as well as a revised coupling procedure allowing for variations in diffuse/direct light partitioning at the surface, and their accounting by the land surface component. Overall, the RCM performance for various variables (e.g., surface fluxes, temperature and precipitation) is improved when using the more advanced 3rd generation LSM. These improvements are of the same order of magnitude as those arising from a new version of the atmospheric component, demonstrating the benefit of using a realistic representation of land surface processes for regional climate simulations. Taking into account variability in diffuse/direct light partitioning at the surface further improves the model performance in terms of summer temperature variability at the monthly and daily time scales. Comparisons with observations show that the RCM realistically captures temporal variations in diffuse/direct light partitioning as well as the evapotranspiration sensitivity to these variations. Our results suggest that a modest but consistent fraction (up to 3 %) of the overall variability in summer temperature can be explained by variations in the diffuse to direct ratio.
The Art of Collaborative Autoethnography: Exploring the Evolution of a Self-Organizing, Non-Traditional Doctoral Cohort  [PDF]
Ashley Gleiman, Davin Knolton, Kevin Mokhtarian
Open Access Library Journal (OALib Journal) , 2015, DOI: 10.4236/oalib.1101634
Abstract: Using collaborative autoethnography methods, this article presents the exploration of three non- traditional doctoral student’s journey as they evolved into a self-organized cohort. Individual processes involving self-authorship, self-observation, personal reflections and analysis, combined with group dialogues and conversations about the experience lead to a formed sense of community amongst the researchers. Composite themes develop through a collaborative analysis of individual personal narratives highlighting significant learning experiences, adult development considerations, and the culturally adaptive nature of non-traditional doctoral students that often remain unexamined in other methodologies.
An Analysis of Buck Converter Efficiency in PWM/PFM Mode with Simulink  [PDF]
Cheng Peng, Chia Jiu Wang
Energy and Power Engineering (EPE) , 2013, DOI: 10.4236/epe.2013.53B013
Abstract:

This technical paper takes a study into efficiency comparison between PWM and PFM control modes in DC-DC buck converters. Matlab Simulink Models are built to facilitate the analysis of various effects on power loss and converting efficiency, including different load conditions, gate switching frequency, setting of voltage and current thresholds, etc. From efficiency vs. load graph, a best switching frequency is found to achieve a good efficiency throughout the wide load range. This simulation point is then compared to theoretical predictions, justifying the effectiveness of computer based simulation. Efficiencies at two different control modes are compared to verify the improvement of PFM scheme.

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