Frequency selective reflection and transmission at a layer composed of a periodic dielectric

The feasibility of using a periodic dielectric layer, composed of alternating bars having dielectric constants epsilon sub 1 and epsilon sub 2, as a frequency selective subreflector in order to permit feed separation in large aperture reflecting antenna systems was examined. For oblique incidence, it is found that total transmission and total reflection can be obtained at different frequencies for proper choices of epsilon sub 1, epsilon 2, and the geometric parameters. The frequencies of total reflection and transmission can be estimated from wave phenomena occurring in a layer of uniform dielectric constant equal to the average for the periodic layers. About some of the frequencies of total transmission, the bandwidth for 90% transmission is found to be 40%. However, the bandwidth for 90% reflection is always found to be much narrower; the greatest value found being 2.5%

Review of In-Building Propagation Phenomena at UHF Frequencies

men both the base station and subscriber antennas are located in the cluttered multipath environment inside buildings, fast fading is observed as either antenna is moved over a distance on the order of a wavelength. The fast fading is evident in measurements made on CWsignals, on individual arrivals forpulsed excitation, even forpulses as short as 5 ns. The statistical properties of the fading are discussed, along with the usual measures of the pulse response, such as path loss, mean excess delay, rms delay spread and coherence bandwidth

Estimating Genetic Ancestry Proportions from Faces

Ethnicity can be a means by which people identify themselves and others. This type of identification mediates many kinds of social interactions and may reflect adaptations to a long history of group living in humans. Recent admixture in the US between groups from different continents, and the historically strong emphasis on phenotypic differences between members of these groups, presents an opportunity to examine the degree of concordance between estimates of group membership based on genetic markers and on visually-based estimates of facial features. We first measured the degree of Native American, European, African and East Asian genetic admixture in a sample of 14 self-identified Hispanic individuals, chosen to cover a broad range of Native American and European genetic admixture proportions. We showed frontal and side-view photographs of the 14 individuals to 241 subjects living in New Mexico, and asked them to estimate the degree of NA admixture for each individual. We assess the overall concordance for each observer based on an aggregated measure of the difference between the observer and the genetic estimates. We find that observers reach a significantly higher degree of concordance than expected by chance, and that the degree of concordance as well as the direction of the discrepancy in estimates differs based on the ethnicity of the observer, but not on the observers' age or sex. This study highlights the potentially high degree of discordance between physical appearance and genetic measures of ethnicity, as well as how perceptions of ethnic affiliation are context-specific. We compare our findings to those of previous studies and discuss their implications

Genetic Drivers of Heterogeneity in Type 2 Diabetes Pathophysiology

Type 2 diabetes (T2D) is a heterogeneous disease that develops through diverse pathophysiological processes1,2 and molecular mechanisms that are often specific to cell type3,4. Here, to characterize the genetic contribution to these processes across ancestry groups, we aggregate genome-wide association study data from 2,535,601 individuals (39.7% not of European ancestry), including 428,452 cases of T2D. We identify 1,289 independent association signals at genome-wide significance (P \u3c 5 × 10-8) that map to 611 loci, of which 145 loci are, to our knowledge, previously unreported. We define eight non-overlapping clusters of T2D signals that are characterized by distinct profiles of cardiometabolic trait associations. These clusters are differentially enriched for cell-type-specific regions of open chromatin, including pancreatic islets, adipocytes, endothelial cells and enteroendocrine cells. We build cluster-specific partitioned polygenic scores5 in a further 279,552 individuals of diverse ancestry, including 30,288 cases of T2D, and test their association with T2D-related vascular outcomes. Cluster-specific partitioned polygenic scores are associated with coronary artery disease, peripheral artery disease and end-stage diabetic nephropathy across ancestry groups, highlighting the importance of obesity-related processes in the development of vascular outcomes. Our findings show the value of integrating multi-ancestry genome-wide association study data with single-cell epigenomics to disentangle the aetiological heterogeneity that drives the development and progression of T2D. This might offer a route to optimize global access to genetically informed diabetes care

Genetic drivers of heterogeneity in type 2 diabetes pathophysiology

Type 2 diabetes (T2D) is a heterogeneous disease that develops through diverse pathophysiological processes1,2 and molecular mechanisms that are often specific to cell type3,4. Here, to characterize the genetic contribution to these processes across ancestry groups, we aggregate genome-wide association study data from 2,535,601 individuals (39.7% not of European ancestry), including 428,452 cases of T2D. We identify 1,289 independent association signals at genome-wide significance (P &lt; 5 × 10-8) that map to 611 loci, of which 145 loci are, to our knowledge, previously unreported. We define eight non-overlapping clusters of T2D signals that are characterized by distinct profiles of cardiometabolic trait associations. These clusters are differentially enriched for cell-type-specific regions of open chromatin, including pancreatic islets, adipocytes, endothelial cells and enteroendocrine cells. We build cluster-specific partitioned polygenic scores5 in a further 279,552 individuals of diverse ancestry, including 30,288 cases of T2D, and test their association with T2D-related vascular outcomes. Cluster-specific partitioned polygenic scores are associated with coronary artery disease, peripheral artery disease and end-stage diabetic nephropathy across ancestry groups, highlighting the importance of obesity-related processes in the development of vascular outcomes. Our findings show the value of integrating multi-ancestry genome-wide association study data with single-cell epigenomics to disentangle the aetiological heterogeneity that drives the development and progression of T2D. This might offer a route to optimize global access to genetically informed diabetes care.</p

Pulse Propagation Characteristics at 2.4 GHz inside Buildings

The growing use of unlicensed wireless systems has spurred interest in the 2.4-GHz ISM band. In order to facilitate the design of such systems, measurements of the pulse response characteristics have been made inside commercial buildings. From the measured pulse response, the statistical properties of the amplitude variation for individual pulses was determined, in addition to the path loss, mean excess delay, root mean square (RMS) delay spread, and the coherence bandwidth of the indoor channelThis work was supported in part by a grant from Symbol Technologies, Inc. and the New York State Science and Technology Foundation

Efficient CDMA System Design for Highway Microcells Based on Accurate Modeling of Path Loss

Out-of-cell interference is an important factor in determining the system capacity of CDMA systems. Out-of-cell interference is influenced by propagation parameters such as slope index s of the path loss model, the standard deviation σ of shadowloss, and the correlation coefficients of shadow loss for propagation from the desired base station and fromthe interfering base station. For line-of-sight (LOS) cells along streets or roadways, propagation may be described by a two-slope model that has smaller slow-fading loss σ and a larger slope index past the breakpoint Rb than thesingle-slope model. As a result, smaller out-of-cell interference is obtained with the two-slope model, leading to system designs having less infrastructure than are obtained using the single-slope model. In this paper we examine how a more realistic prediction of quality of service (QOS) made with the two-slope model leads to cost-effective system designs

Effect of Propagation Modeling on LOS Microcellular System Design

The original publication is available at www.springerlink.com.Linear microcells employing low base station antennas have been proposed for emerging PCS systems. In such systems, the characteristics of the propagation on line-of-sight (LOS) radio links will fundamentally determine the system performance. In this context, it is meaningful to discuss the effect on system design of the two commonly used propagation models, the two-slope model and the single-slope model. In this paper we present several methods to compare the frequency reuse pattern and base station separation based on these two propagation models, and verify the importance of correct propagation modeling for ef® cient system design. We consider interfering signals coming from two cochannel base stations in the first tier, and include slow fading loss when comparing system performances. Based on system design results and subsequent performance, the two-slope model is recommended for LOS PCS microcells