University of Texas at El Paso
  • El Paso, TX, United States
Recent publications
We study the effect of having a female top manager (FTM) on firm performance using World Bank Enterprise Survey data that cover 130,000 firms in 130 mostly developing countries from 2008 to 2017. We show that firms with FTMs underperform their male-led counterparts. FTMs’ underperformance is largely driven by small and medium-sized enterprises and varies widely across world regions. FTMs influence firm performance through affecting firms’ three critical factors of production, which are finance, technology, and labor. Our mediation analyses indicate that the negative FTM–performance relation can be partially mediated by firms’ access to finance, technology usage, and labor selection, which are proxied by lines of credit, internet purchases, and labor cost, correspondingly. This study synthesizes the leadership literature, extends upper echelon and social role theories, and brings clarity to the equivocal findings in the literature on the relation between female leadership and firm performance.
In the Kalahari Copperbelt, the mechanism of regional scale Cu‐Ag mineralization has remained intensely debated between early diagenesis and a single pass during a regional deformation event. At the Zone 5 Cu‐Ag deposit in northwestern Botswana, the orebody is hosted preferentially by chemically reduced metasedimentary rocks that overly oxidized, hematite‐bearing arkosic sandstone. An early diagenetic mineralizing event has been identified which is characterized by fine‐grained stratiform pyrite, including recrystallized framboidal pyrite, intergrown with diagenetic mineral assemblages in the host‐rock. Diagenetic pyrite is in textural equilibrium with chalcopyrite, sphalerite, galena, and (Fe‐Co‐Ni) sulfarsenide. These minerals were subsequently overprinted by a more intense, multi‐stage, structurally‐controlled hydrothermal Cu‐Ag mineralization event related to the Damaran orogeny (~600–480 Ma). The hydrothermal Cu‐Ag mineralization was deposited from hot (~236–265°C), high salinity (19–24.6 wt% NaCl equiv.) hydrothermal ore fluids. Petrographic results reveal an apparent overlap in trace metal associations (Cu, Fe, As, Zn, Pb, Ni, Co) between the two mineralizing events, which can be explained by remobilization of precursor sulfides. The major Ag‐carriers in the ore are chalcocite, covellite, and bornite. The δ34S values of diagenetic pyrite range from −35.8 to +11.4‰, whereas those of hydrothermal epigenetic sulfides, including pyrite, range from −28.0 to +3.0‰. We propose that the hydrothermal sulfides had acquired some bacterially‐reduced sulfur from earlier‐formed minerals. The δ18O and δ13C values of quartz and calcite associated with the hydrothermal mineralization are typical of Neoproterozoic sediment‐hosted Cu‐Ag deposits. However, the δ18O isotopic values of the calcite gangue are anomalously depleted, which is likely due to recrystallization under metamorphic conditions. Our studies at Zone 5 indicate that the Zone 5 Cu‐Ag deposit is the result of a multi‐stage mineralization history that includes both diagenetic and epigenetic events (punctuated by >400 m.y.) facilitated by a strong litho‐structural control. The Zone 5 Cu‐Ag deposit is the result of a multi‐stage mineralization history that includes both diagenetic and epigenetic events, facilitated by a strong litho‐structural control.
A very critical and integral part of the power system is the distribution networks. The final component of the power system, including transmission systems or consumers, is the distribution system (DS). This leads to the highest energy loss that happens. So improving the performance of distribution networks is required not only to provide the reliability of power supply but also to achieve the most economic cost. By optimizing the power flow and simultaneously minimizing the total emission cost and generation cost and taking into account the power losses, these objectives can be achieved. In recent years, heuristic methods are widely employed for solving such complex problems, and The main modern optimization techniques are genetic algorithm(GA). The most important issue in Evolutionary Algorithms is exploration vs. exploitation. Maybe GA is restricted for exploration features, what causes slow convergence and poor robustness Therefore, using the hybridization strategy, the main reason behind this is that such a hybrid approach is expected to create swape between the exploration and exploitation. This work presents performance improvement of a radial distribution networks using a new hybrid optimization technique of Genetic Algorithms (GA) with Equilibrium optimizer (EO) algorithm called Hybrid Genetic Algorithm Equilibrium optimizer (GAEO). It is used for optimum location and size of Renewable Energy Sources (wind energy, photovoltaic, fuel cell) on distribution systems. DG source locations and capacity have strongly influenced the improvement of the distribution network performance by reducing the entire system's power loss, enhancing the voltage profile, reducing fuel costs and emissions of contaminants.
Background Adverse childhood experiences (ACEs) have been historically associated with negative life outcomes among the general population. Objective With limited research among Latinx college students, this study assessed how specific constructs moderate the association between ACEs and alcohol and marijuana use. Participants and setting Latinx participants recruited from a large U.S./Mexico border region university (Females: N = 283, Males: N = 168) completed an online survey which included: demographics, the Center for Youth Wellness Adverse Childhood Experience Questionnaire (CYW ACE-Q) Teen Self-Report, Drug Use Frequency (DUF), Experiences in Close Relationships Scale (ECR), General Self-Efficacy Scale (GSE), Attitudinal Familism Scale (AFS), The Machismo Measure or The Marianismo Beliefs Scale (MBS), and The Bicultural Self-Efficacy Scale (BSE). Methods Hierarchical linear regressions were conducted to test for main and interactive effects and to determine if the individual moderators (i.e., attachment style, self-efficacy, familism, traditional gender norms, bicultural self-efficacy) affect the relationship between ACEs and alcohol and marijuana use. Results Results indicated that among females, attachment style (β = 0.04, p = .03), MBS (β = −65.57, p = .01), and BSE (β = 0.34, p = .04) moderate the relationship between ACEs and alcohol and marijuana use. No moderation analyses were statistically significant among males. Conclusions Clinical implications include, for both substance use and trauma treatment among Latinx college students, the assessment of ACEs and attachment style to promote greater insight into the client's inner struggles and emotional processing in relation to marianismo beliefs and bicultural self-efficacy.
The United States Food and Drug Administration (USFDA) demands that the generic industry prove topical ocular products' pharmaceutical and bioequivalence (BE). In contrast to generic oral drugs, topical ocular product BE testing has proved difficult. New generic versions are compared to an authorized drug product known as a Reference Listed Drug (RLD) to demonstrate their bioequivalence. If the excellent in-vitro results may support the presumption of equivalence in-vivo performance and the only clinically significant difference between the generic and RLD is in its physicochemical qualities and drug release rate, then in-vivo BE studies may be waived. Proving BE through dissolution tests is a golden standard for most conventional dosage forms. However, due to the limited number of biorelevant in-vitro drug release testing (IVRT) approaches capable of differentiating their performance based on product quality and physicochemical properties, the development of generic ophthalmic products has been slow and time-consuming. Often, BE of topical ophthalmic formulations cannot be proved using a single in-vitro test; therefore, an elaborated discussion on various IVRT methods performed to demonstrate bioequivalence of complex generis like ophthalmic emulsions, suspensions, ointments, and gels is necessary. This manuscript aims to review the status of biowaiver criteria for complex ophthalmic products concerning the product-specific FDA guidance to the generic industry.
Local economy should be an important determinant of commercial real estate (CRE) performance. This paper empirically examines how the economic conditions of a metropolitan area drive the performance of CRE in the area. This paper shows that areas with better economic conditions provide a higher total return on commercial properties than those with worse economic conditions. Further analysis indicates that both the income return and capital appreciation of CRE are significantly affected by the size of the economy (proxied as GDP level), while the capital return (but not income return) is significantly affected by the growth of the economy (proxied as GDP growth). The results are largely consistent in the Fama–MacBeth regression, the portfolio analysis, and the propensity score matching model, providing solid evidence on the important effects of local economy on CRE.
Adolescents who befriend drug using peers may be at risk for initiated and continued substance use. The present secondary data analysis examined how drug use homophily (i.e., similarity) in justice-involved boys’ friendship groups relates to their subsequent substance use variety across a period of five years. Participants were 1216 first-time adolescent offenders (Mage Baseline = 15.29; 100% male). Multilevel model analyses revealed that, among participants who entered the study with a history of substance use, drug use homophily was associated with greater subsequent substance use variety. Among participants who entered the study without a history of substance use, this association was no longer significant. The findings have implications for guiding justice system programming aimed at decreasing adolescent offenders’ substance use.
Cancer remains the second most common cause of death in the US. Due to a recurrent problem with anticancer drug resistance, there is a current need for anticancer drugs with distinct modes of action for combination drug therapy We have tested two novel piperidone compounds, named 2608 (1-dichloroacetyl − 3,5-bis(3,4-difluorobenzylidene)-4-piperidone) and 2610 (1-dichloroacetyl-3,5-bis(3,4-dichlorobenzylidene)-4-piperidone), for their potential cytotoxicity on numerous human cancer cell lines. We found that both compounds were cytotoxic for breast, pancreatic, leukemia, lymphoma, colon, and fibroblast cell lines, with a cytotoxic concentration 50% (CC50) in the low micromolar to nanomolar concentration range. Further assays focused primarily on an acute lymphoblastic lymphoma and colon cancer cell lines since they were the most sensitive and resistant to the experimental piperidones. The cell death mechanism was evaluated through assays commonly used to detect the induction of apoptosis. These assays revealed that both 2608 and 2610 induced reactive oxygen species (ROS) accumulation, mitochondrial depolarization, and activated caspase-3/7. Our findings suggest that the piperidones induced cell death via the intrinsic apoptotic pathway. Additional assays revealed that both piperidones cause cell cycle alteration in lymphoma and colon cell lines. Both piperidones elicited DNA fragmentation, as evidenced by an increment in the sub-G0/G1 subpopulation in both cell lines. Similar to other related compounds, both piperidones were found to act as proteasome inhibitors by increasing the levels of poly-ubiquitinated proteins in both lymphoma and colon cell lines. Hence, the two piperidones exhibited attractive cytotoxic properties and suitable mechanisms of action, which makes them good candidates as anticancer drugs.
Background Repetitive transcranial magnetic stimulation (rTMS) is a non-invasive form of brain stimulation that positively regulates the motor and non-motor symptoms of Parkinson's disease (PD). Although, most reviews and meta-analysis have shown that rTMS intervention is effective in treating motor symptoms and depression, very few have used randomised controlled trials (RCTs) to analyse the efficacy of this intervention in PD. We aimed to review RCTs of rTMS in patients with PD to assess the efficacy of rTMS on motor and non-motor function in patients with PD. Methods In this systematic review and meta-analysis, we searched PubMed, MEDLINE and Web of Science databases for RCTs on rTMS in PD published between January 1, 1988 to January 1, 2022. Eligible studies included sham-controlled RCTs that used rTMS stimulation for motor or non-motor symptoms in PD. RCTs not focusing on the efficacy of rTMS in PD were excluded. Summary data were extracting from those RCTs by two investigators independently. We then calculated standardised mean difference with random-effect models. The main outcome included motor and non-motor examination of scales that were used in PD motor or non-motor assessment. This study was registered with PROSPERO, CRD42022329633. Findings Fourteen studies with 469 patients met the criteria for our meta-analysis. Twelve eligible studies with 381 patients were pooled to analyse the efficacy of rTMS on motor function improvement. The effect size on motor scale scores was 0.51 (P < 0.0001) and were not distinctly heterogeneous (I² = 29%). Five eligible studies with 202 patients were collected to evaluate antidepressant-like effects. The effect size on depression scale scores was 0.42 (P = 0.004), and were not distinctly heterogeneous (I² = 25%), indicating a significant anti-depressive effect (P = 0.004). The results suggest that high-frequency of rTMS on primary motor cortex (M1) is effective in improving motor symptoms; while the dorsolateral prefrontal cortex (DLPFC) may be a potentially effective area in alleviating depressive symptom. Interpretation The findings suggest that rTMS could be used as a possible adjuvant therapy for PD mainly to improve motor symptoms, but could have potential efficacy on depressive symptoms of PD. However, further investigation is needed. Funding The National Natural Science Foundation of China (NO: 81873777, 82071414), Initiated Foundation of Zhujiang Hospital (NO: 02020318005), Scientific Research Foundation of Guangzhou (NO: 202206010005), and Science and Technology Program of Guangdong of China (NO: 2020A0505100037).
This article has been retracted: please see Elsevier Policy on Article Withdrawal ( This article has been retracted at the request of the Editors. Following receipt of whistle-blower complaints, an investigation of this and related papers was conducted. The Editor-in-Chief no longer has confidence in the scientific integrity of this paper as similar images have been used in various articles in multiple journals claiming varying conditions, which violates our publishing policies. The XRD pattern in Fig. 5 in this article was reported differently in previous articles (e.g., Construction and Building Materials, 2021, 267, pp.121806, These results are carefully checked and reviewed by a duly constituted expert committee, and are concluded to be unreliable findings. Communication with the corresponding author raised further concerns with the integrity of this work and proposed revisions deepened, rather than clarified, the uncertainty as to what materials were used in this study. One of the conditions of submission of a paper for publication is that authors of reports of original research should present an accurate account of the work performed as well as an objective discussion of its significance. Underlying data should be represented accurately in the paper. A paper should contain sufficient detail and references to permit others to replicate the work. Fraudulent or knowingly inaccurate statements constitute unethical behaviour and are unacceptable. As such this article represents a misuse of the scientific publishing system. The scientific community takes a very strong view on this matter and apologies are offered to readers of the journal that this was not detected during the submission process.
A B S T R A C T Societal demand for vitally important hydrological and other forest ecosystem services (FES) has been rapidly increasing due to accelerating socioeconomic development and global change. Combined with growing threats of water insecurity, complex forest-water interactions are especially challenging to address given the trade-offs among competing FES (e.g., water yield vs carbon sequestration, or biomass production vs biodiversity conservation). The concept of balanced forest ecosystem service management (BFESM) offers a strategy for optimizing the production of multiple FES to meet societal demand and ensure ecological integrity in ways that harmonize both the synergies and tradeoffs across desired FES and the differing and often conflicting needs and priorities of diverse stakeholders. Better understanding the complex and often nonlinear interactions among different FES and how these vary across spatial and temporal scales and different site contexts is critical to developing BFESM strategies. Moreover, the often sharply contrasting FES needs and priorities of different societal groups or stakeholders must be considered in conjunction with information about FES trade-offs. Policy strategies that introduce compensation mechanisms to account for the public good and non-market nature of many highly valued FES (e.g., clean and plentiful water supply, climate regulation) such as Payments for Ecosystem Services (PES), are increasingly being used to foster FES stewardship, yet transitioning from the conventional single FES towards multi-targeted PES (MTPES) approaches could greatly improve the effectiveness of PES schemes. Here, we present five guiding principles of BFESM and discuss the opportunities and challenges of designing effective MTPES policy frameworks. Building on the strengths of each, we then propose an integrated BFESM-MTPES framework for balancing the biophysical understanding of complex synergies and trade-offs across the target FES with the demands and interests of diverse stakeholders. We then discuss specific tools for developing a decision support framework that better integrates and informs strategies for managing forest-water interactions and other FES to achieve BFESM-MTPES goals based on innovative, science-based approaches. We conclude by highlighting key future research directions. Abbreviations: ES, ecosystem services; FES, forest ecosystem services; BFESM, balanced forest ecosystem service management; PES, payments for ecosystem services; STPES, single-targeted payments for ecosystem services; MTPES, multi-targeted payments for ecosystem services. (50 days' free access )
The simulation of field aging using laboratory techniques is an essential prerequisite in the design of high-quality asphalt mixtures. Previous studies in this area have indicated the potential to use an accelerated method for aging loose mixtures using highly oxidative gases, namely ozone and other reactive oxygen species (ROS). Based on that, the present work was concerned with the investigation of the accelerated aging mechanisms in effect and upscaling of the experimental setup to accommodate larger quantity of mixes. Firstly, the chemical transformations and real time oxidation products formed under an ozone rich environment were compared to an air-based environment for three binders using a Vocus proton transfer reaction (PTR-TOF) time-of-flight mass spectrometer. It was observed that the formation of oxygenated species was significantly higher under an ozone rich environment, indicating higher levels of oxidation. The high-resolution level characterization of the oxidation series of several different molecules provided definitive evidence to support the previous hypothesis of using ozone and ROS to fast-track the oxidation of asphalt mixtures. Following this, an experimental method was developed to age up to nine kilograms (kg) of loose mixtures obtained from a mixing plant using ozone and ROS, in a duration of 22 h. After aging, different properties of the mixtures were compared to analogous mixtures aged as per a benchmark method of loose mixture aging at 95 °C for 5 days in a laboratory oven. The various results obtained from the IDEAL-CT tests, rheological and chemical property analyses of extracted binders clearly illustrated the effectiveness of the oxidative gas based aging method for the accelerated aging of loose mixtures, providing comparable levels of aging as traditional methods. Overall, the work conducted in this study provides comprehensive results regarding critical aspects of the developed method and alludes to the opportunity for wide scale applicability.
Context: Multiple myeloma (MM) is the second most common hematological malignancy in the USA, constituting 1.8% of new cases (SEER database). It is a heterogeneous disease that is influenced by sociodemographic factors, with poor survival in non-Hispanic (NH) Blacks and Whites (Pulte et al. 2014). But, clinical characteristics and outcomes of MM are not well understood in Hispanics, one of the fastest-growing populations in the US. Methods: We used the Texas Cancer Registry to evaluate the differences between Hispanic and NH MM patients diagnosed between 1996 to 2016. Socio-demographic characteristics including ethnicity, gender, age, comorbidities, and primary payer were evaluated. Ethnicity was identified as Hispanic and non-Hispanic, and the race as Whites, Blacks, and American Indians. Statistical analysis was performed using SAS software. Hazard ratios (HR) for death and corresponding 95% confidence intervals (CI) were estimated using the cox proportional hazard model. Results: We found 5115 Hispanic and 22426 NH MM patients satisfying the inclusion criteria. Hispanics were diagnosed with MM at a younger age compared to NH (mean (CI) - 65.2 (12.4) vs 68.0 (11.8), P<0.001). Hispanic ethnicity was associated with poor survival after controlling for age at diagnosis, gender, race, and treatment (HR death 1.19, P=0.001). Additionally, increasing age at diagnosis correlated with higher mortality (HR 1.88 in 51-65 years old (yo), HR 2.65 in 66-79 yo, and HR 4.30 in 80+ yo, P=0.001), while females (HR 0.85, P=0.001) and transplant recipients (HR 0.5, P=0.001) had better survival on multivariate cox regression analysis. Blacks (HR 1.17) and American Indians (HR 1.13) did worse when compared with Whites, however, the difference was not statistically significant. Moreover, patients with private insurance had better outcomes than uninsured or Medicare insured (HR 0.85, P=0.049) when controlled for other covariates. Conclusions: To our knowledge, this is the largest analysis reporting outcomes of MM in Hispanics in the USA. While the study is limited by its retrospective nature, the recognition that outcomes in MM patients are impacted by ethnicity is important, which could be related to our findings of earlier age at diagnosis in Hispanics. These data highlight the need for improved access to equitable healthcare and clinical trials for Hispanics.
Abrupt thaw could cause permafrost ecosystems to release more carbon than is predicted from gradual thaw alone. However, thermokarst feature mapping is limited in scope, and observed responses of carbon fluxes to abrupt thaw are variable. We developed a thermokarst detection algorithm that identifies thermokarst features from a single elevation dataset with 71.5 percent accuracy and applied it in Healy, Alaska. Additionally, we investigated the landscape-level variation in carbon dioxide and methane fluxes by extent of abrupt thaw using eddy covariance. Seven percent of the site was classified as thermokarst. Water tracks were the most extensive form of thermokarst, although small pits were much more numerous. Abrupt thaw was positively correlated with carbon uptake during the growing season, when increases in gross primary productivity outpaced increases in ecosystem respiration in vegetation-dense water tracks. However, this was outweighed by higher carbon release in thermokarst features during the nongrowing season. Additionally, abrupt thaw was positively correlated with methane production nearly year-round. Our findings support the hypothesis that abrupt thaw of permafrost carbon will contribute to the permafrost climate feedback above and beyond that associated with gradual thaw and highlights the need to map thermokarst and incorporate abrupt thaw into Earth System Models.
This study aims to develop an alternating polyketone containing cationic groups in one and four alternating positions for increased functionality. A novel polyarylidene ketone was synthesized using simple condensation polymerization of terephthaldehyde and 2,5-hexane dione (PAK) The physicochemical properties of the resulting polymer were evaluated using Fourier-transform infrared spectroscopy, thermogravimetric analysis, X-ray diffraction, UV-Visible absorbance, fluorescence, and SEM investigations. The findings show that the polymer is amorphous, has good thermal stability, and emits red light. It can also be used as a dye adsorbent in aqueous solutions, with high selectivity for the cationic dye methylene blue (MB). The adsorbent efficiency of PAK was measured as a function of pH, dosage, and initial dye concentration; the greatest dye removal of 96 % was obtained at pH 10, 50 mg dosage, and initial dye concentration of 20 ppm. Kinetics and isotherms were studied, showing that the pseudo-second-order model described kinetic data better than Freundlich and Langmuir and revealed a satisfactory chemisorption process. This study suggests that PAK can purify MB dyeing wastewater, remove Zn²⁺, Cu²⁺, Ni²⁺, Co²⁺, Cd²⁺, Fe³⁺ metal ions well, and is selective for Fe³⁺ and Cu²⁺; ion adsorption is chelating-based.
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5,725 members
Igor C. Almeida
  • Department of Biological Sciences
German Rosas-Acosta
  • Department of Biological Sciences
Arshad M. Khan
  • Department of Biological Sciences and Border Biomedical Research Center
Sourav Roy
  • Department of Biological Sciences
Laura Serpa
  • Department of Geological Sciences
500 W University Dr, 79968, El Paso, TX, United States
Head of institution
Heather Wilson
(915) 747-5000