Evaluation of Human Impacts on Bartlett Pond Ecosystem, Laredo, Southern Texas, USA, through Empirical Modeling

The trace elements chemistry of Bartlett Pond, a small shallow wetland pond in Laredo, Southern Texas, was sampled to evaluate the dynamics of trace elements impacts on water quality and ecosystems ecology of the pond. Two types of fish (bass and tilapia) were also sampled to see the trace element accumulation in different parts of their body. The concentrations of trace elements in water samples were found in the following order: Fe ≫Sb > Pb > As ≫Co > Tl > Cr > Cd within Bartlett Pond. Overall, the water quality of the pond is unacceptable for drinking and any other purposes as trace element concentrations (e.g. As, Cd, Co, Cr, Pb, Fe, Sb and Tl) are exceedingly higher (several fold) than the WHO and US EPA guidelines. Predictive and correlation analysis shows that most trace elements exhibit a strong positive correlation among them indicating the same anthropogenic sources and biogeochemical processes regulate these trace elements within the pond. Distributions of the trace elements in water exhibit different shapes mostly as positively skewed distribution for As, Cd, Co, Cr, and Tl, symmetrical distribution for Fe and almost symmetrical distribution for Pb and Sb. Concentrations of As, Co and Tl accumulated much higher in different parts of the Bass than Tilapia fish. The concentrations of As, Tl, Co, and Sb appeared significantly higher in different parts of the body of both Bass and Tilapia than the maximum SRM certified values. Accumulation of these contaminants in fish tissues pose increased health risks to humans who consume these contaminated fish although fishing is prohibited. Anthropogenic activities in the region primarily degrade the whole pond ecosystem ecology of the Bartlett Pond and waters of this pond to be not recommended for any use. These findings may be useful for the scientific community and concerned authorities to improve understanding about these precious natural resources and conservation of the ecosystem ecology.

Seasonal variations of leaf traits and drought adaptation strategies of four common woody species in South Texas, USA

Understanding physiological responses and drought adaptation strategies of woody plant leaf traits in sub-humid to semi-arid regions is of vital importance to understand the interplay between ecological processes and plant resource-allocation strategies of different tree species.Seasonal variations of leaf morphological traits,stoichiometric traits and their relationships of two drought tolerant woody species,live oak(Quercus virginiana)and honey mesquite(Prosopis glandulosa)and two less drought tolerant species,sugarberry(Celtis laevigata)and white ash(Fraxinus americana)were analyzed in a sub-humid to semi-arid area of south Texas,USA.Our findings demonstrate that for the two drought tolerant species,the leguminous P.glandulosa had the highest specific leaf area,leaf N,P,and lowest leaf area and dry mass,indicating that P.glandulosa adapts to an arid habitat by decreasing leaf area,thus reducing water loss,reflecting a resource acquisition strategy.While the evergreen species Q.virginiana exhibited higher leaf dry mass,leaf dry matter content,C content,C:N,C:P and N:P ratios,adapts to an arid habitat through increased leaf thickness and thus reduced water loss,reflecting a resource conservation strategy in south Texas.For the two less drought tolerant deciduous species,the variations of leaf traits in C.laevigata and F.americana varied between Q.virginiana and P.glandulosa,reflecting a trade-off between rapid plant growth and nutrient maintenance in a semi-arid environment.

Tree mortality and biomass loss in drought-aff ected forests of East Texas,USA

Changes in tree mortality due to severe drought can alter forest structure,composition,dynamics,ecosystem services,carbon fl uxes,and energy interactions between the atmosphere and land surfaces.We utilized long-term(2000‒2017,3 full inventory cycles)Forest Inventory and Analysis(FIA)data to examine tree mortality and biomass loss in drought-aff ected forests for East Texas,USA.Plots that experienced six or more years of droughts during those censuses were selected based on 12-month moderate drought severity[Standardized Precipitation Evaporation Index(SPEI)-1.0].Plots that experienced other disturbances and inconsistent records were excluded from the analysis.In total,222 plots were retained from nearly 4000 plots.Generalized nonlinear mixed models(GNMMs)were used to examine the changes in tree mortality and recruitment rates for selected plots.The results showed that tree mortality rates and biomass loss to mortality increased overall,and across tree sizes,dominant genera,height classes,and ecoregions.An average mortality rate of 5.89%year−1 during the study period could be incited by water stress created by the regional prolonged and episodic drought events.The overall plot and species-group level recruitment rates decreased during the study period.Forest mortality showed mixed results regarding basal area and forest density using all plots together and when analyzed the plots by stand origin and ecoregion.Higher mortality rates of smaller trees were detected and were likely compounded by densitydependent factors.Comparative analysis of drought-induced tree mortality using hydro-meteorological data along with drought severity and length gradient is suggested to better understand the eff ects of drought on tree mortality and biomass loss around and beyond East Texas in the southeastern United States.

A simulation study comparing the Texas two-step and the multistage consecutive fracturing method

Multistage hydraulic fracturing in horizontal wells is a critical technique for developing unconventional oil and gas resources.Stress interactions among neighboring fractures cause immature fracture development.The Texas two-step fracturing(TTSF)method is a new technique that aims to enhance fracture complexity and conductivity.This paper compares the fracture development of consecutive fracturing and the TTSF.The fracturing sequence in the multistage fracturing method has a significant effect on the fracture length,fracture width and injection pres sure.The consecutive fracturing results in relatively uneven fracture length and width.Certain fractures in consecutive fracturing are restrained to be closed due to the strong stress shadowing effect.In contrast,TTSF has considerable potential for alleviating the negative effects of stress interactions and producing a larger stimulated reservoir volume.

Extending the Economic Life of the Ogallala Aquifer with Water Conservation Policies in the Texas Panhandle

The continued decline in the availability of water from the Ogallala Aquifer in the Texas Panhandle has led to an increased interest in conservation policies designed to extend the life of the aquifer and sustain rural economies. Four counties were chosen for evaluation. This study evaluates the effectiveness of five policies in terms of changes in the saturated thickness, crop mix, water use per acre, and the net present value of farm profits over a 60-year planning horizon. The dynamic optimization models were developed using GAMS for the baseline as well as one for all five of the policy alternatives for each county. Results indicate that the policy scenarios of biotechnology adoption and a water use restriction will conserve the most water among the policies analyzed. In terms of economic returns, the biotechnology adoption policy by far provides the greatest benefit to producers due to yield increases that are estimated with current annual growth rates in new seed varieties. The water use restriction policy, on the other hand, has the lowest net present value of returns, indicating that conservation is accompanied with significant costs to producers. The irrigation adoption technology scenario is the next best policy in terms of net present value of returns (following biotechnology);however, it ranks last in terms of reducing aquifer depletion. It is important to note that while the models do not perfectly predict the factors being evaluated, it is the basis for comparison between the policy scenarios which are important. These comparisons will aid policy makers in determining the most effective strategy to conserve water while simultaneously considering the economic costs to producers. In addition, the results of this study can be applied to other areas facing similar conditions, either currently or in the future, throughout the Texas Panhandle.

Texas Crisis Highlights Grid Vulnerabilities

In February 2021,during a massive blackout in Texas,USA,a man made the news for using his hybrid Ford F-150 pickup truck,a model equipped with a generator,to power his house for three days[1].Other hybrid F-150 owners followed suit,and Ford requested that its Texas dealerships lend out the trucks on their lots so that more people could access these mini-power stations during the week-long disaster[2].That some residents had to rely on their pickup trucks to provide electricity for their homes illustrates the severity of the grid crisis that paralyzed Texas.For an average of 42 h,69%of Texans had no electricity(Fig.1)[3],leaving many homes without heat as temperatures fell to record lows.About half of the population also lacked running water because water plants lost power[3].According to the state’s figures,hypothermia,carbon monoxide poisoning,and other storm-related causes exacerbated by the power outage killed at least 210 people[4],but one analysis put the death toll at 700[5].The economic price tag,including damage to homes and businesses from burst pipes,may be as high as 200 billion USD[6].

基于Texas(HEFR)法倭肯河流域中下游段河道生态基流量计算

文章通过Tennant法和Texas法(HEFR)生态基流量计算方法对倭肯河中下游进行生态需水量计算,以倭肯河中游倭肯水文站水文数据为例,通过Tennat法和Texas法对倭肯河流域生态基流量进行成果分析,以探求出Texas方法在东北地区河流的适用程度。

High-Speed Rail Route and Regional Mobility with a Ras-ter-Based Decision Support System: The Texas Urban Triangle Case

This study addresses sustainable transportation in the Texas Urban Triangle at the regional scale. Its aim is to determine the most suitable corridor for new transport infrastructure by employing a spatial decision support system proposed in this project. The system is being tested through its application to a prototype corridor parallel to Interstate 35 between San Antonio and Austin. The basic research questions asked are spatial in nature, so accordingly the geographic information system is the primary method of data analysis. The overall modeling approach is devoted to answering the following questions: What are the considerations to support sustainable growth? What scale or type of infrastructure is necessary? And how to adequately model the transportation corridors to meet the demands and to sustain the living environment at the same time?

Texas从头计算程序的移植和应用

本文叙述Texas梯度法从头计算程序的改编和移植工作,并运用移植后的程序对甲硝胺等分子的基态平衡几何构型实现了全优化计算.

Modeling and Mapping Flood Hazard with a Flood Risk Assessment Tool: A Case Study of Austin, Texas

As a hazard, flood is an extremely important indicator of how a city is resilient to waterborne diseases and epidemics. Over many decades, flood as a hazard has been a major factor in inducing displacement of marginalized section of the people. Austin city within Central Texas has been identified as one of the major hotspots for flooding in recent decades. Thus, the objectives of the paper are two folded: 1) Empirically, we analyzed and mapped out the susceptibility levels from the factors of physical environments to assess the risk of urban flooding (rainfall data, surface water bodies and topography);in Austin, Texas and 2) Methodologically, we created a re-useable ArcGIS scripting tool that can be used by researchers to automate the process of flood risk modelling with certain criteria. The paper showcases a novel time sensitive building of a tool which will enable better visibility of flood within the city of Austin.

Case Study: Reviewing Methods of Assessing Community Adaptive Capacity for Jefferson County, Texas

With the increased attention on community sustainability and resilience, different poles have developed voicing similarities and/or differences of the two concepts. This study quantifies adaptive capacity of Jefferson County, Texas, one of the coastal communities at the Gulf of Mexico having some of the worse adverse effects. Review of existing methods is presented. Analyses were conducted for the last ten years: from 2005 to 2014. Interestingly, statistical analyses showed that the County’s socio-economic profile or indicators have not changed throughout the ten years, but the environmental, institutional, and infrastructure indicators have. Focusing on one location magnifies the adaptive capacity of Jefferson County, the temporal aspect of both perspectives, and the relevance of existing methods to this community with its peculiarities. Future assessments need to be based on primary data collected through participatory engagement of all stakeholders. This calls for attempts to quantify adaptive capacity using the comparatively more challenging deductive reasoning, which would allow for incorporation of more risks and thus higher readiness.

Exploratory Analyses for Water Quality of the Gulf of Mexico Basin, Texas, 2005-2014

With the increased demand for more water sources, the issues of water quality have become more important. This study presents exploratory data analyses on water quality issues related to the Gulf of Mexico Basin in Texas for the last decade: 2005-2014. Dissolved oxygen, water temperature, specific conductance, PH, transparency, sampling depth and Enterococci observations for the ten years from 2005 to 2014 were analyzed. Statistical testing showed that the observations followed similar distributions between the years. Thus they were combined for each of the variables. Throughout the ten years transparency, water temperature, specific conductance, and Enterococci showed higher variances. Pair-wise correlations were negligible but they had positive spatial autocorrelation. Sampling was constantly conducted in the four months of February, May, August, and November. Water temperature, dissolved oxygen and Enterococci concentrations varied significantly during these four months. Univariate spatial regressions showed that Enterococci is predicted to increase whereas dissolved oxygen, PH, water temperature, specific conductances were predicted to decrease.

Age, Race and Gender Spatiotemporal Disparities of COPD Emergency Room Visits in Houston, Texas

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.

Multivariate Geostatistical Model for Groundwater Constituents in Texas

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.

Generalizations of the Feline and Texas Chainsaw Josephus Problems

We define and study the Extended Feline Josephus Game, a game in which n players, each with ℓlives, stand in a circle. The game proceeds by alternating between hitting k consecutive players—each of whom will consequently lose a life—and skipping s consecutive players. This cycle continues until every player except one loses all of their lives. Given the nonnegative integer parameters n, k, s and ℓ, the goal of the game is to identify the surviving player. In this paper, we show how the defining parameters n, k, s, and ℓaffect the survivor of games with specific constraints on those parameters and our main results provide new closed formulas to determine the survivor of these Extended Feline Josephus Games. Moreover, for cases where these formulas do not apply, we provide recursive formulas for reducing the initial game to other games with smaller parameter values. For the interested reader, we present a variety of directions for future work in this area, including an extension which considers players lying on a general graph, rather than on a circle.

过程安全管理体系对BP Texas事故探析

危化品生产过程的安全事故所造成的经济损失和社会影响均较大,必须从根源上消除,至少也要极大程度地减缓。BP Texas炼油厂爆炸和火灾事故是美国近40年来最严重的工厂灾难之一,也是一起典型的过程安全事故。以过程安全管理(PSM)体系要素分析方法对该事故进行研究,系统地探讨该事故的原因。可以看出,多个要素严重违反体系要求为该事故发生的关键原因。同时以实例证明PSM体系的重要性,通过控制其中要素的严重偏离,实现从根源上和管理体系上消除重大安全事故风险的目标。

Does Climatic Variability Influence Agricultural Land Prices under Differing Uses? The Texas High Plains Case

The Texas High Plains faces projections of increasing temperature and declining precipitation in the future on account of its semi-arid climate. This research evaluated the impact of climatic variability on agricultural land prices under different land uses in the Texas High Plains, employing the Ricardian approach of land climate pricing over a study period of 1991-2011. The results indicate that climatic variability had a greater impact on irrigated land prices as compared to dryland and ranchland. This study could be instrumental in predictive market analyses of rural land values in semi-arid economies which are vulnerable to future climate change.

Use of Interspecific Hybrids in the Texas A&M University Cotton Improvement Laboratory

Integrating alleles from Gossypium species into G.hirsutum is important for the enhancement of genetic variability and for creating polymorphism useful in molecular mapping studies.Through collaborative efforts,several species including G.barbadense,G.tomentosum,and G.mustelinum

Texas Prototypes找准定位

居于印刷电路板(PCB)的设计与生产之间的工作实在是既耗时又耗精力的黑洞,正是这些环节需要重配置、重写、测试以及再测试等工作。Texas Prototypes抓住这些黑洞并且将之转化成了美妙的sweet spot(最佳位置)。