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Deformation of the Fermi surface of a spinless two-dimensional electron gas in presence of an anisotropic Coulomb interaction potential
No full textWe consider the stability of the circular Fermi surface of a two-dimensional electron gas system against an elliptical deformation induced by an anisotropic Coulomb interaction potential. We use the jellium approximation for the neutralizing background and treat the electrons as fully spin-polarized (spinless) particles with a constant isotropic (effective) mass. The anisotropic Coulomb interaction potential considered in this work is inspired from studies of two-dimensional electron gas systems in the quantum Hall regime. We use a Hartree–Fock procedure to obtain analytical results for two special Fermi liquid quantum electronic phases. The first one corresponds to a system with circular Fermi surface while the second one corresponds to a liquid anisotropic phase with a specific elliptical deformation of the Fermi surface that gives rise to the lowest possible potential energy of the system. The results obtained suggest that, for the most general situations, neither of these two Fermi liquid phases represent the lowest energy state of the system within the framework of the family of states considered in this work. The lowest energy phase is one with an optimal elliptical deformation whose specific value is determined by a complex interplay of many factors including the density of the system
Results for the electrostatic potential of a uniformly charged hemispherical surface
No full textWe study the form of the electrostatic potential created by a hemispherical surface with uniform surface charge density. We specifically consider a “northern” hemispherical surface and try to obtain analytical expressions for the electrostatic potential at an arbitrary point in space. Some compact analytical results are obtained for special cases and an interesting mathematical integral formula is derived as a by-product of the approach. The results suggest that a general expression for the electrostatic potential at an arbitrary point in space, if possible, would be very hard to obtain in compact analytical form
Exploring state-level variabilities between perceived community resilience and posttraumatic stress symptoms during the COVID-19 pandemic: Multilevel modeling approach.
No full textConsidering the variabilities in the spread of the novel coronavirus (causing COVID-19) in the United States, the current study aimed at examining the variabilities in people’s levels of posttraumatic stress symptoms (PTSS) across the states. Specifically, the associations between PTSS and both individual-level factors (i.e., perceived community resilience, symptoms of COVID-19, and demographic variables) and state-level factors (i.e., state population, population density, the proportion of African American individuals, gross domestic product per capita, and a number of COVID-19 cases), as well as a potential moderation effect of a state-level factor between perceived community resilience and PTSS were examined. The final sample included 548 participants nested within 46 states of the United States, who participated in the study via Amazon’s Mechanical Turk between April 2 and April 9t, 2020. There were significant associations between all individual-level factors and PTSS. Regarding the association between the state-level factors and PTSS, states with greater population and COVID-19 cases were associated with higher levels of PTSS, although population density was negatively associated with PTSS. Furthermore, the percentage of African American individuals residing in a state moderated the relation between perceived community resilience and PTSS. The moderating effect of gross domestic product per capita was also marginally significant. These results imply the importance of taking into account the state-level variabilities in examining PTSS during the COVID-19 pandemic. (PsycInfo Database Record (c) 2021 APA, all rights reserved
A Stochastic Knapsack Game: Revenue Management in Competitions
Get PDFWe study a mathematical model for revenue management under competitions with multiple sellers. The model combines the stochastic knapsack problem, a classic revenue management model, with a non-coorperative game model that characterizes the sellers’ rational behavior. We are able to establish a dynamic recursive procedure that incorporate the value function with the utility function of the games. The formalization of the dynamic recursion allows us to establish some fundamental structural properties
On the Generalization of Interval Valued fuzzy Generalized Bi-ideals in Ordered Semigroups
Get PDFIn this paper, a new general form than interval valued fuzzy generalized bi-ideals in ordered semigroups is introduced. The concept of interval valued fuzzy generalized bi-ideals is initiated and several properties and characterizations are provided. A condition for an interval valued fuzzy generalized bi-ideal to be an interval valued fuzzy generalized bi-ideal is obtained. Using implication operators and the notion of implication-based an interval valued fuzzy generalized bi-ideal, characterizations of an interval valued fuzzy generalized bi-ideal and an interval valued fuzzy generalized bi-ideal are considered
Commutative Monoid on Symmetrical Difference Operator Over Intuitionistic Fuzzy Matrices
Get PDFIn this article, we extend the mathematical operation symmetrical difference (⊖) to intuitionistic fuzzy matrix. Various properties of the difference operator ’⊖’ are discussed over intuitionistic fuzzy matrices. Also associativity property of the above said operator is studied when each entry of an intuitionistic fuzzy matrix is either intuitionistic fuzzy tautological or co tautological since it is very critical when we prove that in usual manner. Finally, a commutative monoid algebraic structure is obtained on symmetrical difference operator over intuitionistic fuzzy matrices
Factors That Impact The Graduation Of Students Who Enroll In Workforce Programs At A Community College In Southeast Texas
No full textChairs of Advisory Committee: Pamela Barber-Freeman and Jerrell Moore Community colleges are used by many high school students as a catalyst to earn a four-year degree or gain skills needed to enter the workforce (Curry, 2013’ Ma & Baum, 2016; Palmadessa, 2017). Cohen and Brawer (2008) described community colleges as two-year institutions that offer associate degrees and technical certificates for students who are not fully ready to attend a four-year university. While recruiting students for community college programs is aligned with the mission, keeping students enrolled until graduation is daunting (Kronenberger, 2012; Shapiro et al., 2016). According to the National Center for Education Statistics (2020), graduation rates at community colleges are comparatively lower than at four-year institutions.
The purpose of this research was to investigate the factors that influenced graduation from a Workforce Development program at a Southeast Texas community college. College-based workforce programs provide students with industry-particular skills for employment (Bromberg & Theokas, 2016; United States Department of Education, 2019). Although there are numerous studies of Career and Technical Education programs, few studies solely feature workforce programs at community colleges.
The researcher selected a quantitative research design and used numerical observations by means of a logistic regression model to determine whether graduation from workforce programs was predictive. The sample consisted of 300 students enrolled in a community college in Southeast Texas. Given the non-significance of the entire model, there was no practical significance to the effect of age. The researcher collected the primary data for this research from a community college data bank and placed the data in an Excel format. The data on the spreadsheet was used to compute a logistic regression model using Social Package for Social Sciences (SPSS) version 26. The tabulations for the variables showed the sample of CTE/Workforce Development students were mostly male, Hispanic, and enrolled in law enforcement courses. The available demographic information showed a high proportion of students with household incomes under $15,000 and with parents who completed high school. Of those students who had college readiness coursework, most completed the Texas Success Initiative (TSI) test. For the overall proposed model, there was a significant predictor of program completion. The direction of the coefficient indicated there was a significant difference at the p\u3c.05 level for students based on their race.
These findings are important because they provided school administrators another viewpoint when considering methods to improve the graduation of workforce students at community colleges. Furthermore, the findings in this study can be the impetus to future studies that focus on topics beneficial to non-White groups such as African American and Hispanic male students. Future research may dig deeper in examining community colleges\u27 graduation and retention tendencies with other variables. These topics may not only help school administrators, policymakers, and educators but students of color as well.
Keywords: community college workforce programs; community college retentio
Data without Democracy: The Cruel Optimism of Education Technology and Assessment
No full textThis essay examines contemporary digital educational assessment and argues that there are underlying problematic values and consequences entailed by the datafication of education as coupled with assessment practices. By applying Dewey’s work concerning curriculum, aims, growth, and the conception of democracy through education to current methods, this examination exposes digital assessment as perpetuating a cruel optimism through assessment that undermines democratic, progressive functions of education. Dewey’s philosophy provides a perspective from which to repurpose digital tools in a manner that fosters, rather than hinders, aims, growth, and democracy in education
Vanillin based polymers: V. Poly(hydrovanilloin–urethane)
No full textRenewable resources based hydrovanilloin [1,2-bis(4-hydroxy-3-methoxyphenyl)-1,2-ethanediol] was synthesized in 86% yield by electrochemical dimerization of vanillin in aqueous NaOH. This symmetrical bis-phenol monomer was then used for the preparation of urethane polymers by two different methods. In the first method a 1:2 mole ratio mixture of hydrovanilloin and diisocyanate was polymerized in DMF using 1,4-diazabicyclo[2,2,2]octane as the catalyst at 60°C, for 1 h to give poly(hydrovanilloin–urethane)s. In the second method diisocyanates were first reacted with polyethylene glycol-400 to give pre-polymers. Then prepolymers were reacted with equivalent amount of hydrovanilloin at 60°C for 4 days to produce poly(hydrovanilloin-ethylene glycol-urethane)s. The first method resulted hard poly(hydrovanilloin–urethane)s showing Tg values in the range of 121–172°C. The second method yielded softer poly(hydrovanilloin-ethylene glycol-urethane)s and these polymers failed to show distinct glass transition temperatures in the DSC analysis. However, poly(hydrovanilloin-ethylene glycol-urethane)s showed better thermal stabilities than polymers without polyethylene glycol units
Prediction of soil erosion risk using earth observation data under recent emission scenarios of CMIP6
No full textThe earth observation data and CMIP6 models were used to predict plausible soil loss from the Ghaghara river basin. The decadal prediction of soil loss (28.64 ton/ha/year) was found high for SSP585 of CanESM5 during 2015–2025. However, the lower value was reported as 21.71 ton/ha/year for SSP245 of MRI-ESM2-0 during 2035–2045. The century level future rainfall erosivity factor was found lowest for SSP245, however highest for SSP585 of Access-ESM1-5, CanESM5, and IPSL-CM6A-LR. The SSP585 (Access-ESM1-5, CanESM5, and IPSL-CM6A-LR) have maximum soil erosion rate as 29.07, 28.03, and 28.0 ton/ha/year, respectively. For the SSP585, increments were observed as 35.93%, 31.04%, and 30%, respectively, compared to the baseline year (2014). Whereas, lowest was reported as 21.7 and 24.9 ton/ha/year and consequently the low increment as 1.31% and 16.55% for both scenarios of MRI-ESM2-0 compared to baseline. We observed that the soil erosion rate is aligned with the predicted rainfall erosivity factor