San Diego State University

About: San Diego State University is a education organization based out in San Diego, California, United States. It is known for research contribution in the topics: Population & Poison control. The organization has 12418 authors who have published 27950 publications receiving 1192375 citations. The organization is also known as: SDSU & San Diego State College.

Hybrid Fractal Shape Planar Monopole Antenna Covering Multiband Wireless Communications With MIMO Implementation for Handheld Mobile Devices

Abstract: A hybrid fractal shape planar monopole antenna covering multiple wireless communication bands is presented for multiple-input-multiple-output (MIMO) implementation for handheld mobile devices. The proposed structure is the combination of Minkowski island curve and Koch curve fractals. It is placed with edge to edge separation of 0.16λ0 at 1.75 GHz. The T-shape strip is inserted and rectangular slot is etched at top side of ground plane, respectively to improve the impedance matching and isolation between the antennas. A measured impedance matching fractional bandwidths ( S11 ≤ -10 dB) are 14% from 1.65 GHz to 1.9 GHz for the band 1 and 80% from 2.68 GHz to 6.25 GHz for the band 2. Acceptable agreement is obtained between the simulated and measured antenna performance parameters. These characteristics demonstrate that the proposed antenna is an attractive candidate for handheld mobile devices.

Variability in exchange of CO2 across 12 northern peatland and tundra sites

Abstract: Many wetland ecosystems such as peatlands and wet tundra hold large amounts of organic carbon (C) in their soils, and are thus important in the terrestrial C cycle. We have synthesized data on the carbon dioxide (CO2) exchange obtained from eddy covariance measurements from 12 wetland sites, covering 1-7 years at each site, across Europe and North America, ranging from ombrotrophic and minerotrophic peatlands to wet tundra ecosystems, spanning temperate to arctic climate zones. The average summertime net ecosystem exchange of CO2 (NEE) was highly variable between sites. However, all sites with complete annual datasets, seven in total, acted as annual net sinks for atmospheric CO2. To evaluate the influence of gross primary production (GPP) and ecosystem respiration (R-eco) on NEE, we first removed the artificial correlation emanating from the method of partitioning NEE into GPP and R-eco. After this correction neither R-eco (P = 0.162) nor GPP (P = 0.110) correlated significantly with NEE on an annual basis. Spatial variation in annual and summertime R-eco was associated with growing season period, air temperature, growing degree days, normalized difference vegetation index and vapour pressure deficit. GPP showed weaker correlations with environmental variables as compared with R-eco, the exception being leaf area index (LAI), which correlated with both GPP and NEE, but not with R-eco. Length of growing season period was found to be the most important variable describing the spatial variation in summertime GPP and R-eco; global warming will thus cause these components to increase. Annual GPP and NEE correlated significantly with LAI and pH, thus, in order to predict wetland C exchange, differences in ecosystem structure such as leaf area and biomass as well as nutritional status must be taken into account.

Murine Noroviruses Comprising a Single Genogroup Exhibit Biological Diversity despite Limited Sequence Divergence

Abstract: Viruses within the genus Norovirus of the family Caliciviridae are the major cause of acute, nonbacterial gastroenteritis worldwide. Human noroviruses are genetically diverse, with up to 57% divergence in capsid protein sequences, and comprise three genogroups. The significance of such genetic diversity is not yet understood. The discovery of murine norovirus (MNV) and its ability to productively infect cultured murine macrophages and dendritic cells has provided an opportunity to determine the functional consequences of norovirus diversity in vitro and in vivo. Therefore, we compared the full-length genomes of 21 new MNV isolates with five previously sequenced MNV genomes and demonstrated a conserved genomic organization consisting of four open reading frames (ORFs) and a previously unknown region of nucleotide conservation in ORF2. A phylogenetic analysis of all 26 MNV genomes revealed 15 distinct MNV strains, with up to 13% divergence at the nucleotide level, that comprise a single genotype and genogroup. Evidence for recombination within ORF2 in several MNV genomes was detected by multiple methods. Serological analyses comparing neutralizing antibody responses between highly divergent strains suggested that the MNV genogroup comprises a single serotype. Within this single genogroup, MNV strains exhibited considerable biological diversity in their ability to grow in culture and to infect and/or persist in wild-type mice. The isolation and characterization of multiple MNV strains illustrate how genetic analysis may underestimate the biological diversity of noroviruses and provide a molecular map for future studies of MNV biology.

Illicit drug use among Mexicans and Mexican Americans in California: the effects of gender and acculturation

Abstract: Aims. To examine the effects of gender and acculturation on illicit drug use among the Mexican-origin population in California. Design. The 3012 subjects between 18 and 59 years of age were selected under a stratified, multi-stage cluster sampling method. Setting. Fresno County in California is primarily agricultural, with only one metropolitan area. Over 30% of the total population of 764 800, are Hispanics, of Mexican origin. Measurements. A modified version of the World Health Organization's Composite International Diagnostic Instrument (WHO-CIDI) was used to ascertain drug use. Respondents were considered drug users if they had ever used marijuana, cocaine, hallucinogens, heroin or inhalants. Acculturation was measured with a Likert scale, assessing English vs. Spanish language preference. Other covariates of interest were nativity and place of residence. Findings. Men had higher rates of use than women for every drug (men = 46.3%, women = 23.2%). Urban rates were higher than rural rates, for both women (urban = 32.8% vs. rural = 16.6%) and men (urban = 57.0% vs. rural = 36.8%). In logistic regression models, men were more likely than women to have ever used illicit drugs or inhalants (adjusted OR = 4.8), cocaine (adjusted OR = 5.3) or marijuana (OR = 4.3). However, the combined effect of United States nativity and acculturation, on drug use, was greater among women (adjusted OR = 29.3) than among men (adjusted OR = 7.4). The effect of acculturation was stronger among urban, than among town or rural residents. Conclusions. Acculturation and United States nativity are risk factors for illicit drug use among Mexican origin men and women. However, women have increased vulnerability compared with men. Findings reinforce the need for culturally based public health interventions.