Classical properties of low-dimensional conductors: Giant capacitance and non-Ohmic potential drop

Electrical field arising around an inhomogeneous conductor when an electrical current passes through it is not screened, as distinct from 3D conductors, in low-dimensional conductors. As a result, the electrical field depends on the global distribution of the conductivity sigma(x) rather than on the local value of it, inhomogeneities of sigma(x) produce giant capacitances C(omega) that show frequency dependence at relatively low omega, and electrical fields develop in vast regions around the inhomogeneities of sigma(x). A theory of these phenomena is presented for 2D conductors.Comment: 5 pages, two-column REVTeX, to be published in Physical Review Letter

Designing a Crowd-Based Relocation System—The Case of Car-Sharing

Car-sharing services promise environmentally sustainable and cost-efficient alternatives to private car ownership, contributing to more environmentally sustainable mobility. However, the challenge of balancing vehicle supply and demand needs to be addressed for further improvement of the service. Currently, employees must relocate vehicles from low-demand to high-demand areas, which generates extra personnel costs, driven kilometers, and emissions. This study takes a Design Science Research (DSR) approach to develop a new way of balancing the supply and demand of vehicles in car-sharing, namely crowd-based relocation. We base our approach on crowdsourcing, a concept by which customers are requested to perform vehicle relocations. This paper reports on our comprehensive DSR project on designing and instantiating a crowd-based relocation information system (CRIS). We assessed the resulting artifact in a car-sharing simulation and conducted a real world car-sharing service system field test. The evaluation reveals that CRIS has the potential for improving vehicle availability, increasing environmental sustainability, and reducing operational costs. Further, the prescriptive knowledge derived in our DSR project can be used as a starting point to improve individual parts of the CRIS and to extend its application beyond car-sharing into other sharing services, such as power bank- or e-scooter-sharing

TGF-β inhibitor Smad7 regulates dendritic cell-induced autoimmunity

TGF-β is an anti-inflammatory cytokine whose signaling is negatively controlled by Smad7. Previously, we established a role for Smad7 in the generation of autoreactive T cells; however, the function of Smad7 in dendritic cells (DCs) remains elusive. Here, we demonstrate that DC-specific Smad7 deficiency resulted in elevated expression of the transcription factors Batf3 and IRF8, leading to increased frequencies of CD8(+)CD103(+) DCs in the spleen. Furthermore, Smad7-deficient DCs expressed higher levels of indoleamine 2,3-dioxygenase (IDO), an enzyme associated with tolerance induction. Mice devoid of Smad7 specifically in DCs are resistant to the development of experimental autoimmune encephalomyelitis (EAE) as a result of an increase of protective regulatory T cells (Tregs) and reduction of encephalitogenic effector T cells in the central nervous system. In agreement, inhibition of IDO activity or depletion of Tregs restored disease susceptibility. Intriguingly, when Smad7-deficient DCs also lacked the IFN-γ receptor, the mice regained susceptibility to EAE, demonstrating that IFN-γ signaling in DCs mediates their tolerogenic function. Our data indicate that Smad7 expression governs splenic DC subset differentiation and is critical for the promotion of their efficient function in immunity

Conductance Ratios and Cellular Identity

Recent experimental evidence suggests that coordinated expression of ion channels plays a role in constraining neuronal electrical activity. In particular, each neuronal cell type of the crustacean stomatogastric ganglion exhibits a unique set of positive linear correlations between ionic membrane conductances. These data suggest a causal relationship between expressed conductance correlations and features of cellular identity, namely electrical activity type. To test this idea, we used an existing database of conductance-based model neurons. We partitioned this database based on various measures of intrinsic activity, to approximate distinctions between biological cell types. We then tested individual conductance pairs for linear dependence to identify correlations. Contrary to experimental evidence, in which all conductance correlations are positive, 32% of correlations seen in this database were negative relationships. In addition, 80% of correlations seen here involved at least one calcium conductance, which have been difficult to measure experimentally. Similar to experimental results, each activity type investigated had a unique combination of correlated conductances. Finally, we found that populations of models that conform to a specific conductance correlation have a higher likelihood of exhibiting a particular feature of electrical activity. We conclude that regulating conductance ratios can support proper electrical activity of a wide range of cell types, particularly when the identity of the cell is well-defined by one or two features of its activity. Furthermore, we predict that previously unseen negative correlations and correlations involving calcium conductances are biologically plausible

Retrospective evaluation of whole exome and genome mutation calls in 746 cancer samples

Funder: NCI U24CA211006Abstract: The Cancer Genome Atlas (TCGA) and International Cancer Genome Consortium (ICGC) curated consensus somatic mutation calls using whole exome sequencing (WES) and whole genome sequencing (WGS), respectively. Here, as part of the ICGC/TCGA Pan-Cancer Analysis of Whole Genomes (PCAWG) Consortium, which aggregated whole genome sequencing data from 2,658 cancers across 38 tumour types, we compare WES and WGS side-by-side from 746 TCGA samples, finding that ~80% of mutations overlap in covered exonic regions. We estimate that low variant allele fraction (VAF < 15%) and clonal heterogeneity contribute up to 68% of private WGS mutations and 71% of private WES mutations. We observe that ~30% of private WGS mutations trace to mutations identified by a single variant caller in WES consensus efforts. WGS captures both ~50% more variation in exonic regions and un-observed mutations in loci with variable GC-content. Together, our analysis highlights technological divergences between two reproducible somatic variant detection efforts

Supporting Land-Use Mapping by Using Multitemporal Thermal Infrared Imagery in Conjunction with a Simple Diurnal Temperature Model

We propose an algorithm for deriving surface specific information from a multitemporal thermal data set with a simple model of the diurnal temperature curve. Based on an analytic solution of the heat conduction equation (Price 1977) this algorithm allows the determination of the thermal inertia and of the linearization coefficients of the outgoing heatfluxes for each pixel of a multitemporal thermal image by fitting the model to the respective temperature values. At least three temperature measurements at different times of one day are needed for that process. For computational convenience we introduce a function representing the ratio of two temperature differences. The determined model parameters are analyzed regarding their usefulness for land-use mapping. The algorithm was tested on a multitemporal multispectral image data set recorded by a DAEDALUS AADS 1268 line scanner. The test site was an agricultural area near the city of Nuremberg, Germany. The data was recorded at 4:30 a.m...

1997 Simulation of High Resolution Satellite Imagery from Multispectral Airborne Scanner Imagery for . . .

For the years 1997 to 2000 it is expected that a number of new satellites will be launched into orbit by private companies which are specified to deliver panchromatic imagery of the earth surface with a spatial resolution as fine as 1 m. In contrast to the panchromatic band, the spectrally resolved bands will have a four times coarser ground resolution. Therefore, image fusion algorithms will certainly be employed in order to produce `sharpened&apos; color imagery. The new satellites have the potential of stimulating and expanding the remote sensing market for image products at a resolution around one meter. In order to prepare for this era we have examined image fusion algorithms using already available airborne imagery. This paper tests fusion algorithms on imagery which was simulated using multispectral images of an airborne scanner (DAEDALUS ATM) with an average resolution of 1 m. The main advantage of a simulation of satellite images is the possibility to immediately check the deviatio..

Study of Sealed Surfaces and Diurnal Temperature Variations in Urban Environments with Airborne Scanner Data

The composition of surfaces in urban areas has a strong influence on urban climate and therefore on the quality of life. In general sealed surfaces will cause a stronger daytime heating in comparison to vegetated areas. Using remotely sensed data it is possible to monitor the extent of surface sealing and its effect on surface temperature. Furthermore, the determination of thermal behaviour with regard to solar heating can be used to discriminate between different surface types. In this study we investigate the usefulness of remotely sensed temperatures of a part of the diurnal brightness temperature curve for unsupervised classification purposes in an urban environment, in particular for sealed and unsealed surfaces. Thermal image data were taken with the thermal IR channel of the Daedalus AADS 1268 scanner at four different times (4:30, 8:30, 11:30, 12:30 MET). We propose a straightforward method to classify a scene into vegetated and non vegetated regions based solely on thermal dat..

Accuracy Assessment Of Vegetation Monitoring With High Spatial Resolution Satellite Imagery

For the years 1997 to 2000 it is expected that a number of new satellites will be launched into orbit by private companies which are specified to deliver panchromatic imagery of the earth surface with a spatial resolution as fine as 1m. In contrast to the panchromatic band, the spectrally resolved bands will have a four times coarser ground resolution. Therefore, image fusion algorithms will be employed in order to produce panchromatic-`sharpened&apos; color imagery. The new satellites have the potential of stimulating and expanding the remote sensing market for image products at a resolution around one meter. In order to prepare for this era we have examined image fusion algorithms using already available airborne imagery. This paper describes tests of fusion algorithms on imagery which was simulated using multispectral images of an airborne scanner (DAEDALUS ATM) with an average pixel size of 1m. The main advantage of this simulation of satellite images is the possibility to measure quant..