Texas Southern University
Texas Southern University, School of Public Affairs: Digital ScholarshipNot a member yet
21372 research outputs found
Sort by
Combined molecular-dynamics and quantum-trajectories simulation of laser-driven, collisional systems
No full textWe introduce a combined molecular-dynamics and quantum-trajectories code to simulate the effects of near-resonant optical fields on state-vector evolution and particle motion in a collisional system. In contrast to collisionless systems, in which the quantum dynamics of multilevel, laser-driven particles with spontaneous emission can be described with the optical Bloch equations (OBEs), particle velocities in sufficiently collisional systems change on timescales comparable to those of the laser-induced, quantum-state dynamics. These transient velocity changes can cause the time-averaged velocity dependence of the quantum state to differ from the OBE solution. We use this multiscale code to describe laser cooling in a strontium ultracold neutral plasma. Important phenomena described by the simulation include suppression of electromagnetically induced transparencies through rapid velocity changing collisions and thermalization between cooled and uncooled directions for anisotropic laser cooling
Methods for Identifying Truck Crash Hotspots
Get PDFThe goal of this study was to develop a new method for identifying the actual risky spots by using the geographic information system (GIS). For this purpose, in this study, three different methods for detecting hotspots are developed, i.e., (1) the annual average daily traffic (AADT) normalization method, (2) AK crashes (A is the incapacitating crash, and K is the fatal crash) percentage method, and (3) distribution difference method. To evaluate the performances of these three hotspot detection methods along with a baseline method that only considered the frequency of crashes, we applied these three methods to identify the top 20 hotspots for truck crashes in two representative areas in Texas. The results indicated that (1) all three proposed methods produced more reasonable results than the baseline method, and (2) the distribution difference method outperformed the other methods
Verification of Cryptocurrency Mining Using Ethereum
Get PDFWith advancement in computer technology, financial technology has also evolved. Blockchain technology has evolved over the past decade; however, this has also resulted in some malicious attacks. To earn mining rewards of a blockchain, a new type of attack, called cryptojacking, has emerged in the online world. This attack uses the computer resources of a victim to obtain mining rewards without user confirmation. However, this monetization model was originally intended to replace advertising as a source of revenue for a website. To resolve such problems, a storage verification architecture based on smart contracts was proposed in the study. The decentralized system of blockchain enables users to identify and participate in verification of mining sites through Ethereum smart contracts
Improving Bus Transit Services for Disabled Individuals: Demand Clustering, Bus Assignment, and Route Optimization
Get PDFBus transit provides shorter-distance public transportation services, which are subject to various disability discrimination acts with various dedicated features. The Americans with Disabilities Act (ADA) requires that disabled individuals shall have equal rights to receive fare bus transit services, including fixed-route and door-to-door bus services. Most previous studies were mainly focused on policy aspects as part of the efforts of disability rights. The proper planning of demand requests from disabled individuals has been a critical issue but has gained insufficient attention. The existing methodologies in planning route for special transit buses for disabled individuals normally do not consider passengers\u27 waiting time, lack sufficient flexibility, and have strict restrictions on the total number of served destinations. This paper proposes a four-module based methodology for the planning of bus transit, including demand information collection, demand clustering, transit bus assignment, and a linear programming-based route planning with different objective functions. Houston MetroLift bus transit service was employed as an example to illustrate the proposed method. Three scenarios during the route planning module were designed in this case study: (1) planning for pre-timed shortest distance, (2) planning for the pre-timed shortest waiting time of passengers, and (3) flexible planning. Results showed that scenario 1 obtained the shortest total travel time and the highest benefit for bus providers, scenario 2 is with the shortest average waiting time, while scenario 3 is real-time based with longer total travel time and longer waiting time. Scenarios 2 and 3 consider the special needs of disabled passengers
Egyptian Artbrospira phytosterols: Production, identification, antioxidant and antiproliferative activities
No full textCultivation of microalgae as a source of phytosterol and other lipid compounds has gained more attention for commercial applications in pharmaceutical, cosmetic and food function industries. In this research, native Spirulina maxima SM from Egypt was grown in individual cultures containing various concentrations of nitrogen (N), phosphorus (P) and sulfur (S) elements in order to elucidate the effect of its elements on lipid and phytosterols production and to evaluate its antioxidant and antiproliferative activities. The results revealed that the SM was able to grow in different concentrations of testing elements S (from 0.3 to 2.4 mM), P (from 0.3 to 2.4 mM) and N (0.3 to 3.2 mM) with significant differences. A high potential for production of MS biomass, total lipid and phytosterol contents were obtained in individual cultures containing 0.6 mM N, 0.6 mM P and 0.80 mM, respectively. Therefore, these concentrations (combination of S+P+N element) were selected for cultivation of SM at large scale in a column photobioreactor (PBR 300 L) to induce sufficient SM biomass so that, we can obtain an adequate amount of total lipid and phytosterol contents. Phytosterols (PS) of native SM grown in the 300 L PBR were partially purified from unsaponified extracts of SM total lipid followed by its purification by crystallization process. The identification and quantification of PS profile were performed by GC-FID analysis. The results revealed high levels of campsterol, D7-Avena sterol, β-sitosterol, stigmasterol and other compounds. These PS compounds showed marked in vitro superoxide, DPPH and OH radical scavenging activity, which was comparable with the results obtained with standard antioxidants BHA or α-tocopherol. Moreover, SM phytosterols exhibited anti-proliferative activity against three human cancer cell lines (MCF-7, Hep-G2 and HCT-116) with IC50 values less than 11.62 fig/mL as assessed by in vitro MTT colorimetric method. Thus, SM phytosterol may be considered as a potential natural source of promising ingredient in the future for a range of health applications for human, cosmetic industries and in functional food
Addressing power dynamics in community-engaged research partnerships
Get PDFBackground: Successful community-engaged research depends on the quality of the collaborative partnerships between community -members and academic researchers and may take several forms depending on the purpose which dictates the degree to which power dynamics are handled within the collaborative arrangement. Methods: To understand the power dynamics and related concepts within community-engaged research arrangements, a secondary analysis of an existing qualitative data set was undertaken. Two models of community-engaged research, a review of literature, and the applied experiences of researchers familiar with community engagement practices confirmed the power dynamics concepts used to carry out the analysis of the qualitative data set according to the principles of directed content analysis. This analysis yielded quotes on power dynamics and related issues. Tools to address the power dynamics exposed by the quotes were selected using the literature and lived experience of the researchers. Finally, to ensure trustworthiness, the selected quotes on power dynamics and the recommended tools were subjected to naturalistic treatment using peer debriefings and triangulation. Results: Analysis of existing qualitative data made clear that community-engaged research between health practitioners and communities may take several forms depending on the purpose and dictate how power dynamics, including inequities, biases, discrimination, racism, rank and privilege, are handled within the collaborative arrangement. Three tools including implicit bias training, positionality, and structural competency may be used to address power dynamics and related concepts. Conclusion: Analysis of the qualitative data set highlighted the power dynamics within different community-engaged research models and the tools that may be used to address inequitable power dynamics including implicit bias training, positionality, and structural competency
Temporal trends of gestational malaria in the United States
Get PDFBackground: Although regarded as rare in the United States (US), increased global traffic and importation of malaria from endemic countries may lead to a rise in gestational malaria in the US. Methods: This multi-year retrospective study analyzed trends in diagnosed cases of gestational malaria from 2002 to 2017 using joinpoint regression models. We also assessed the association between gestational malaria and selected maternal-fetal adverse outcomes. Results: Mothers diagnosed with gestational malaria tended to be older, and the majority of diagnosed cases (52.9%) were among Non-Hispanic (NH) Blacks. Diagnosed cases of gestational malaria are on the rise in the US. Mothers diagnosed with gestational malaria were 5 times as likely (OR = 5.05, 95% CI: 4.05–6.29) to be anemic as compared to those without malaria. Compared to NH-Whites, NH-Black mothers were twice as likely to experience stillbirth, had nearly 50% greater adjusted odds of severe preeclampsia, and had about 30% elevated likelihood for preterm labor. Conclusions: There is a need to dedicate appropriate resources to identify women that are at risk for gestational malaria in order to prevent related pregnancy complications
Bioanalytical assay development and validation for the pharmacokinetic study of gmc1, a novel fkbp52 co-chaperone inhibitor for castration resistant prostate cancer
Get PDFBackground: GMC1 (2-(1H-benzimidazol-2-ylsulfanyl)-N-[(Z)-(4-methoxyphenyl) methylideneamino] acetamide) effectively inhibits androgen receptor function by binding directly to FKBP52. This is a novel mechanism for the treatment of castration resistant prostate cancer (CRPC). Methods: an LC-MS/MS method was developed and validated to quantify GMC1 in plasma and urine from pharmacokinetics studies in rats. An ultra-high-performance liquid chromatography (UHPLC) system equipped with a Waters XTerra MS C18 column was used for chromatographic separation by gradient elution with 0.1% (v/v) formic acid in water and methanol. A Sciex 4000 QTRAP® mass spectrometer was used for analysis by multiple reaction monitoring (MRM) in positive mode; the specific ions [M+H]+ m/z 340.995 → m/z 191.000 and [M+H]+ m/z 266.013 → m/z 234.000 were monitored for GMC1 and internal standard (albendazole), respectively. Results: GMC1 and albendazole had retention times of 1.68 and 1.66 min, respectively. The calibration curves for the determination of GMC1 in rat plasma and urine were linear from 1–1000 ng/mL. The LC-MS/MS method was validated with intra-and inter-day accuracy and precision within the 15% acceptance limit. The extraction recovery values of GMC1 from rat plasma and urine were greater than 95.0 ± 2.1% and 97.6 ± 4.6%, respectively, with no significant interfering matrix effect. GMC1 is stable under expected sample handling, storage, preparation and LC-MS/MS analysis conditions. Conclusions: Pharmacokinetic evaluation of GMC1 revealed that the molecule has a biexponential disposition in rats, is distributed rapidly and extensively, has a long elimination half-life, and appears to be eliminated primarily by first order kinetics
Potential role of drug metabolizing enzymes in chemotherapy-induced gastrointestinal toxicity and hepatotoxicity
No full textIntroduction: Toxicity of chemotherapy drugs is the leading cause of poor therapeutic outcome in many cancer patients. Gastrointestinal (GI) toxicity and hepatotoxicity are among the most common side effects of current chemotherapies. Emerging studies indicate that many chemotherapy-induced toxicities are driven by drug metabolism, but very few reviews summarize the role of drug metabolism in chemotherapy-induced GI toxicity and hepatotoxicity. In this review, we highlighted the importance of drug metabolizing enzymes (DMEs) in chemotherapy toxicity. Areas covered: Our review demonstrated that altered activity of DMEs play important role in chemotherapy-induced GI toxicity and hepatotoxicity. Besides direct changes in catalytic activities, the transcription of DMEs is also affected by inflammation, cell-signaling pathways, and/or by drugs in cancer patients due to the disease etiology. Expert opinion: More studies should focus on how DMEs are altered during chemotherapy treatment, and how such changes affect the metabolism of chemotherapy drug itself. This mutual interaction between chemotherapies and DMEs can lead to excessive exposure of parent drug or toxic metabolites which ultimately cause GI adverse effect
Formation of argon cluster with proton seeding
No full textWe employ force-field molecular dynamics simulations to investigate the kinetics of nucleation to new liquid or solid phases in a dense gas of particles, seeded with ions. We use precise atomic pair interactions, with physically correct long-range behaviour, between argon atoms and protons. Time dependence of molecular cluster formation is analysed at different proton concentration, temperature and argon gas density. The modified phase transitions with proton seeding of the argon gas are identified and analysed. The seeding of the gas enhances the formation of nano-size atomic clusters and their aggregation. The strong attraction between protons and bath gas atoms stabilises large nano-clusters and the critical temperature for evaporation. An analytical model is proposed to describe the stability of argon-proton droplets and is compared with the molecular dynamics simulations