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Rejoinder of ``Cross-Covariance Functions for Multivariate Geostatistics''  [PDF]
Marc G. Genton,William Kleiber
Statistics , 2015, DOI: 10.1214/15-STS519
Abstract: Rejoinder of ``Cross-Covariance Functions for Multivariate Geostatistics'' by Genton and Kleiber [arXiv:1507.08017].
The impact of urbanization and institutions of higher education on Houston Texas’ Third Ward Community
AI Akpan
Journal of Applied Sciences and Environmental Management , 2006,
Abstract: University towns are influenced by the features of urbanization and impact greatly on the health of the inhabitants. This paper evaluates the impacts of urbanization on the Third Ward communities that are located within Texas Southern University and the University of Houston. The paper further assesses how characteristics of the urban environment may have affected the population health. The historical background of the Third Ward Houston Texas is first reviewed to determine the extent to which urbanization and the presence of universities have impacted on the quality of life of the residents. The overall effects of urbanization are reviewed using all the available literature with broad emphasis on the physical, and social environments, and access to health and social services. Irrespective of the presence of universities and colleges, the surrounding neighborhood communities of the Third Ward Houston continue to face formidable historic challenges to improving public health and general quality of life. Although, urbanization has brought about reinvestment initiatives, changing demographics, and growth creating changes that offer new opportunities for improving health while requiring that health systems be adapted to residents' health needs, however, the communities remain stagnant and unique. Ultimately, the key factors affecting the quality of life in the Third Ward communities are the physical environment, the social environment, and access to health and social services. Overall, the neighborhood communities of the Third Ward do not seem to respond positively to developmental influence of the universities and colleges and are negatively impacted by urbanization. It is suggested that improvement in the Third Ward areas should require setting local, state, and national agendas for progress. Therefore, certain priorities must be put in place namely, development must reorient around the educational and population dynamics, including cultural diversity, and the growing numbers of elderly. @JASEM
The Impacts of Oilfield-Related Booms and the Overall Safeties Implications in Houston Harris County, Texas and Surrounding Areas!  [PDF]
Park E. Atatah, Catherine W. Kisavi-Atatah
Open Journal of Social Sciences (JSS) , 2015, DOI: 10.4236/jss.2015.312011
Abstract: This study investigates the impacts of oil/gas hydraulic fracking in Houston Harris County, Texas and surrounding areas. Recently, the increase in preventable roads accidents had been a concern to many Houstonians and surrounding areas residents. Further, the deplorable condition of the public roads was yet another concern primarily blamed on the implications of oil and gas hydraulic fracking in Houston Harris County, Texas and surrounding areas. The study found a statistical significant difference in Houston population increase between 2010 and 2014 as hydraulic fracking expands. We also found a symmetric statistical significant increase in fatal roads’ accidents in less than 5 years, along with deplorable infrastructures. Additionally, we found a continued symmetric collective price drops in oil and gas; yet, the price of Houston, Texas median house increased astronomically to unaffordable levels for native Houstonians. The outlined findings of this study should hopefully pinpoint some of the public policy implication issues created by excessive hydraulic fracking in Houston Harris County, Texas and surrounding areas. Finally, the pinpointed recommendations should be useful in refocusing public policy decision makers in addressing some of the identified pressing public policy implications in Houston Harris County, Texas and surrounding areas; which could possibly bring some positive social changes eventually.
Primary and secondary sources of formaldehyde in urban atmospheres: Houston Texas region
D. D. Parrish, T. B. Ryerson, J. Mellqvist, J. Johansson, A. Fried, D. Richter, J. G. Walega, R. A. Washenfelder, J. A. de Gouw, J. Peischl, K. C. Aikin, S. A. McKeen, G. J. Frost, F. C. Fehsenfeld,S. C. Herndon
Atmospheric Chemistry and Physics (ACP) & Discussions (ACPD) , 2012,
Abstract: We evaluate the rates of secondary production and primary emission of formaldehyde (CH2O) from petrochemical industrial facilities and on-road vehicles in the Houston Texas region. This evaluation is based upon ambient measurements collected during field studies in 2000, 2006 and 2009. The predominant CH2O source (92 ± 4% of total) is secondary production formed during the atmospheric oxidation of highly reactive volatile organic compounds (HRVOCs) emitted from the petrochemical facilities. Smaller contributions are primary emissions from these facilities (4 ± 2%), and secondary production (~3%) and primary emissions (~1%) from vehicles. The primary emissions from both sectors are well quantified by current emission inventories. Since secondary production dominates, control efforts directed at primary CH2O emissions cannot address the large majority of CH2O sources in the Houston area, although there may still be a role for such efforts. Ongoing efforts to control alkene emissions from the petrochemical facilities, as well as volatile organic compound emissions from the motor vehicle fleet, will effectively reduce the CH2O concentrations in the Houston region. We do not address other emission sectors, such as off-road mobile sources or secondary formation from biogenic hydrocarbons. Previous analyses based on correlations between ambient concentrations of CH2O and various marker species have suggested much larger primary emissions of CH2O, but those results neglect confounding effects of dilution and loss processes, and do not demonstrate the causes of the observed correlations. Similar problems must be suspected in any source apportionment analysis of secondary species based upon correlations of ambient concentrations of pollutants.
Age, Race and Gender Spatiotemporal Disparities of COPD Emergency Room Visits in Houston, Texas  [PDF]
Faye Anderson, Arch Carson, Lawrence Whitehead, Keith Burau
Occupational Diseases and Environmental Medicine (ODEM) , 2015, DOI: 10.4236/odem.2015.31001
Chronic obstructive pulmonary disease (COPD) is one of the major causes of morbidity and mortality in the United State. The investigation of the continuing increase in its prevalence and mortality has increased attempts to further understand its causes and how to manage it. Understanding the spatial and temporal distribution of COPD emergency room (ER) visits in Harris County (Houston) can guide these efforts in a uniform yet diverse setting like this one. The objectives of this study were to identify the temporal and spatial variations of COPD emergency room visits adjusted by age, gender, ethnicity, day of the week, month, and year, and to estimate the odds ratio of COPD emergency room visits adjusted by the six risk factors. The dataset used were extracted from two resources: ER Utilization Study and Harris County centroid coordinates. Exploratory statistical analyses were conducted to study the spatiotemporal disparities and investigate associations. Logistic regression was performed to estimate the odds ratio of COPD primary diagnosis adjusted for age, race, gender, day of the week, month, and year. The number of COPD ER visits kept increasing from 2004 throughout 2009 but there was a significant increase after the year 2005. Spring and summer had lower visits compared to winter and autumn. Lowest visits were during June and July and higher during December and January. Tuesdays had the highest number of visits compared to the remaining days of the week with Saturdays having had the lowest number of visits. Temporal analyses show the continuous increase in COPD ER visits in Houston as well as the consistent spatial disparities between zip regions. After adjustment for age, race, gender, day of the week, month, and year, there were statistically significant associations between emergency room chronic obstructive pulmonary disease diagnoses in Houston, Texas, with these six predictors.
Cross-Covariance Functions for Multivariate Geostatistics  [PDF]
Marc G. Genton,William Kleiber
Statistics , 2015, DOI: 10.1214/14-STS487
Abstract: Continuously indexed datasets with multiple variables have become ubiquitous in the geophysical, ecological, environmental and climate sciences, and pose substantial analysis challenges to scientists and statisticians. For many years, scientists developed models that aimed at capturing the spatial behavior for an individual process; only within the last few decades has it become commonplace to model multiple processes jointly. The key difficulty is in specifying the cross-covariance function, that is, the function responsible for the relationship between distinct variables. Indeed, these cross-covariance functions must be chosen to be consistent with marginal covariance functions in such a way that the second-order structure always yields a nonnegative definite covariance matrix. We review the main approaches to building cross-covariance models, including the linear model of coregionalization, convolution methods, the multivariate Mat\'{e}rn and nonstationary and space-time extensions of these among others. We additionally cover specialized constructions, including those designed for asymmetry, compact support and spherical domains, with a review of physics-constrained models. We illustrate select models on a bivariate regional climate model output example for temperature and pressure, along with a bivariate minimum and maximum temperature observational dataset; we compare models by likelihood value as well as via cross-validation co-kriging studies. The article closes with a discussion of unsolved problems.
Multivariate Geostatistical Model for Groundwater Constituents in Texas  [PDF]
Faye Anderson
International Journal of Geosciences (IJG) , 2014, DOI: 10.4236/ijg.2014.513132
Abstract: Although many studies have explored the quality of Texas groundwater, very few have investigated the concurrent distributions of more than one pollutant, which provides insight on the temporal and spatial behavior of constituents within and between aquifers. The purpose of this research is to study the multivariate spatial patterns of seven health-related Texas groundwater constituents, which are calcium (Ca), chloride (Cl), nitrate (NO3), sodium (Na), magnesium (Mg), sulfate (SO4), and potassium (K). Data is extracted from Texas Water Development Board’s database including nine years: 2000 through 2008. A multivariate geostatistical model was developed to examine the interactions between the constituents. The model had seven dependent variables—one for each of the constituents, and five independent variables: altitude, latitude, longitude, major aquifer and water level. Exploratory analyses show that the data has no temporal patterns, but hold spatial patterns as well as intrinsic correlation. The intrinsic correlation allowed for the use of a Kronecker form for the covariance matrix. The model was validated with a split-sample. Estimates of iteratively re-weighted generalized least squares converged after four iterations. Matern covariance function estimates are zero nugget, practical range is 44 miles, 0.8340 variance and kappa was fixed at 2. To show that our assumptions are reasonable and the choice of the model is appropriate, we perform residual validation and universal kriging. Moreover, prediction maps for the seven constituents are estimated from new locations data. The results point to an alarmingly increasing levels of these constituents’ concentrations, which calls for more intensive monitoring and groundwater management.
Proximity of Residence to Bodies of Water and Risk for West Nile Virus Infection: A Case-Control Study in Houston, Texas
Melissa S. Nolan,Ana Zangeneh,Salma A. Khuwaja,Diana Martinez,Susan N. Rossmann,Victor Cardenas,Kristy O. Murray
Journal of Biomedicine and Biotechnology , 2012, DOI: 10.1155/2012/159578
Abstract: West Nile virus (WNV), a mosquito-borne virus, has clinically affected hundreds of residents in the Houston metropolitan area since its introduction in 2002. This study aimed to determine if living within close proximity to a water source increases one’s odds of infection with WNV. We identified 356 eligible WNV-positive cases and 356 controls using a population proportionate to size model with US Census Bureau data. We found that living near slow moving water sources was statistically associated with increased odds for human infection, while living near moderate moving water systems was associated with decreased odds for human infection. Living near bayous lined with vegetation as opposed to concrete also showed increased risk of infection. The habitats of slow moving and vegetation lined water sources appear to favor the mosquito-human transmission cycle. These methods can be used by resource-limited health entities to identify high-risk areas for arboviral disease surveillance and efficient mosquito management initiatives.
Healthcare Resource Utilization for Recurrent Clostridium difficile Infection in a Large University Hospital in Houston, Texas  [PDF]
Samuel L. Aitken, Tiby B. Joseph, Dhara N. Shah, Todd M. Lasco, Hannah R. Palmer, Herbert L. DuPont, Yang Xie, Kevin W. Garey
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0102848
Abstract: Background There are limited data examining healthcare resource utilization in patients with recurrent Clostridium difficile infection (CDI). Methods Patients with CDI at a tertiary-care hospital in Houston, TX, were prospectively enrolled into an observational cohort study. Recurrence was assessed via follow-up phone calls. Patients with one or more recurrence were included in this study. The location at which healthcare was obtained by patients with recurrent CDI was identified along with hospital length of stay. CDI-attributable readmissions, defined as a positive toxin test within 48 hours of admission and a primary CDI diagnosis, were also assessed. Results 372 primary cases of CDI were identified of whom 64 (17.2%) experienced at least one CDI recurrence. Twelve of 64 patients experienced 18 further episodes of CDI recurrence. Of these 64 patients, 33 (50.8%) patients with recurrent CDI were readmitted of which 6 (18.2%) required ICU care, 29 (45.3%) had outpatient care only, and 2 (3.1%) had an ED visit. Nineteen (55.9%) readmissions were defined as CDI-attributable. For patients with CDI-attributable readmission, the average length of stay was 6±6 days. Conclusion Recurrent CDI leads to significant healthcare resource utilization. Methods of reducing the burden of recurrent CDI should be further studied.
Correlates of susceptibility to smoking among Mexican origin youth residing in Houston, Texas: A cross-sectional analysis
Anna V Wilkinson, Andrew J Waters, Vandita Vasudevan, Melissa L Bondy, Alexander V Prokhorov, Margaret R Spitz
BMC Public Health , 2008, DOI: 10.1186/1471-2458-8-337
Abstract: We analyzed cross-sectional survey data from 1,187 participants who reported they had never smoked, even a puff of a cigarette. The survey assessed peer and family social influence, school and neighborhood characteristics, level of family acculturation and socioeconomic status, and attitudes toward smoking. Bivariate associations, Student's t-tests, and logistic regression analysis were used to examine predictors of susceptibility.Overall, 22.1% of the never-smokers were susceptible to smoking. Boys were more likely to be susceptible than girls (25.6% vs. 18.9%), and susceptible children were slightly older than non-susceptible children (12.1 vs. 11.8 years). In addition, multivariate analyses revealed that positive expectations about smoking exerted the strongest influence on susceptibility status (odds ratio = 4.85). Multivariate analyses further revealed that compared to non-susceptible participants, susceptibles were more likely to report peer influences supportive of smoking, lower subjective social status and more detentions at school, more temptations to try smoking and to have a mother and a brother who smokes.Our findings suggest that interventions that target positive expectations about smoking may be useful in this population. Furthermore, because youth encounter smoking-initiation risk factors in different social environments, our results underscore the continued need for both family- and school-based primary prevention programs to adequately combat their influence. The results also can be used to inform the development of culturally sensitive programs for Mexican origin youth.The construct of cognitive susceptibility to smoking, defined as lacking a firm commitment not to smoke in the future or if offered a cigarette by a friend, integrates behavioral intentions and expectations for future behavior [1]. Over the past decade, the construct has consistently demonstrated strong predictive abilities and has become widely accepted. In prospective studies, co
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