California State University
  • Long Beach, United States
Recent publications
  • Yertai Tanai
    Yertai Tanai
  • Kamil Ciftci
    Kamil Ciftci
Improving student graduation is of utmost importance for higher education institutions, both public and private. The key contribution of this study is to apply the uplift modeling framework to optimize preparatory course assignments as an instrument to boost student success for graduation. Specifically, we concentrate on two university programs, English and Math preparatory courses, to identify students who would benefit the most from these courses and successfully graduate. To achieve this objective, we analyze 10-years of incoming freshmen data with a wide range of feature variables from a major university in the US. We then build and test several uplift methodologies to determine students’ response to the treatments. The best-performing model allows us to identify students in different segments and target those who are most responsive to the treatment to achieve optimal results. Additionally, we identify the most significant variables and provide student profiles and attributes that distinguish those who would gain from preparatory courses from those who would not. The framework developed in this study can serve as a valuable tool for decision-making and policy support. It can improve not only the student success perspective, but also the allocation of university resources by identifying and advising a fraction of students who would benefit from taking these preparatory courses and have a positive impact on their graduation.
  • Amelia Stone-Johnstone
    Amelia Stone-Johnstone
Many postsecondary institutions across the United States have adopted the corequisite model of academic support to facilitate student learning and the successful completion of introductory mathematics courses within students’ first year of college enrollment. While research have highlighted the benefits of corequisites in terms of academic outcomes, there is little qualitative research on the impact of this model of academic support on students beyond course grades. Through student narratives, this study documents how one university implemented their College Algebra corequisite and investigates the impact of the classroom climate of a corequisite course on students’ attitudes toward mathematics. This study shows that though the classroom climate positively impacted the participants’ attitudes toward mathematics in general, the climate of the corequisite specifically had a greater impact on their beliefs about mathematics and perceptions of themselves as learners of mathematics. However, there were some identified drawbacks to the corequisite course including time-consuming coursework and occasionally unproductive group collaboration. These findings highlight the potential for corequisites to foster positive attitudes toward mathematics, yet it also demonstrated a need for greater intention in the course development to ensure a coherent course structure where course activities and assessments give way to meaningful and productive student engagement.
Numerous tropical macroalgae provide associational refuge to other benthic organisms, presumably due to their physical structure and/or production of chemical metabolites. One feature determining their effectiveness as an associational refuge is likely to be the size of the organism benefitting from the refuge. Using a manipulative experiment in the back reef of Moorea, French Polynesia, we tested if the macroalga Turbinaria ornata provided an associational refuge from fish corallivores for small colonies of massive Porites spp., and how this differed with colony size (20–100 mm diameter). Tissue loss through corallivory increased with colony size but was ~ 72% less for Porites colonies associated with T. ornata versus colonies separated from this macroalga, while dense macroalgae beds on contemporary reefs negatively impact the recruitment, growth and survival of corals, small colonies of Porites appear to benefit, through reduced corallivory, by associating with the macroalga Turbinaria. This association may come at a cost (e.g., reduced growth) and should be the focus of future research.
Patterns of morphological divergence across species’ ranges can provide insight into local adaptation and speciation. In this study, we compared phenotypic divergence among 4,221 crickets from 337 populations of two closely related species of field cricket, Gryllus firmus and G. pennsylvanicus , and their hybrids. We found that these species differ across their geographic range in key morphological traits, such as body size and ovipositor length, and we directly compared phenotype with genotype for a subset of crickets to demonstrate nuclear genetic introgression, phenotypic intermediacy of hybrids, and essentially unidirectional mitochondrial introgression. We discuss how these morphological traits relate to life history differences between the two species. Our comparisons across geographic areas support prior research suggesting that cryptic variation within G. firmus may represent different species. Our study highlights how variable morphology can be across wide-ranging species and the importance of studying reproductive barriers in more than one or two transects of a hybrid zone.
Virus-like particles (VLPs) have long attracted the attention of biologists and metrologists due to their dual nature. Despite their similarity to viruses, VLPs lack a virus DNA or RNA, thereby posing no threat of infection. The development of methods for the creation and standardization of VLPs, as well as for monitoring their characteristics, represents an important problem in the field of biotechnology and molecular biology. In this work, we aim to substantiate the requirements, methods, and instruments used to ensure the traceability of VLP-based certified reference materials (CRMs). The following methods for characterization of biological and physicochemical properties of such CRMs were considered: mass balance; high-performance liquid chromatography-mass spectrometry (HPLC–MS); gas chromatography-mass spectrometry (GC–MS); Karl Fischer coulometric titration; ion chromatography; inductively coupled plasma mass spectrometry; and isotope dilution. It was established that VLP-based CRMs should meet the following requirements: the presence of molecular patterns common to many pathogenic biological agents (PBAs) but absent in the organism; traceability to SI units (Systeme international d’unites, SI); the absence of own genetic material; the presence only of inactivated homogenous strains when used for vaccine delivery. VLP-based CRMs facilitate metrological support in the field of medicine and vaccine production.
The present study aims to generalize the experience of creating state reference materials (GSOs) of active substances and determine their main characteristics, standardized both in the State Pharmacopoeia of the Russian Federation and in the regulatory documents of the measurement uniformity assurance system. In connection with the violation of supply chains, the acquisition and use of foreign reference active substances became quite problematic or even impossible. As a consequence of the current difficult situation with the insufficient nomenclature of GSOs, the domestic manufacturers and developers faced urgent problems in creating them. The development of antimicrobial reference active substances will solve urgent issues of strengthening the technological sovereignty of Russia, minimize the import dependence of the Russian economy, as well as ensure the targets of the Strategy for Scientific and Technological Development of the Russian Federation to be achieved. The conclusions of the study can be applied in creating GSOs to substitute imported reference materials or surpass their level.
African American women bear a mental health burden and are less likely to seek and receive appropriate services than their dominant culture peers. African Americans may underutilize professional counseling services due to factors such as stigma, healthy cultural mistrust, and cultural values. To date, researchers have paid limited attention to ways to break through barriers to mental health equity. This phenomenological study examined the lived experiences of ten African American women who sought service from licensed professional counselors. Participants sought help after failure of self-care and traditional supports, recognized barriers, and approached counseling as a last resort. Through counseling, they found new perspectives, surprise connections, and opportunities for growth. Findings inform communities about what counseling is (and is not) as well as different types of support that can be obtained from a professional counselor. Limitations and future research directions are discussed.
Background Muslim Arab immigrants are a fast-growing, under-studied, and underserved minority population in the United States. Little is known about breastfeeding practices in this population. Objectives The objective of this study was to describe infant feeding practices and factors associated with these practices among immigrant Muslim Arab women. Design A nonexperimental-one group, cross-sectional, descriptive, prospective design was used to identify infant feeding practices among immigrant Muslim Arab women. Methods A convenience sample of one hundred sixteen immigrant Muslim Arab women with at least one child five years or younger was recruited from a large metropolitan area in the Southwestern region. Participants completed the social ecological model of health promotion self-reported questionnaire. Descriptive statistics were performed to identify infant feeding practices and logistic regression was used to identify factors associated with these practices. Results Immigrant Muslim Arab mothers demonstrate high breastfeeding initiation rates (99.2%) and lengthy breastfeeding duration ( M = 11.86, SD = 8.04), but low rates of exclusive breastfeeding at six months (21.6%). The most frequent reasons for early termination of breastfeeding were perceived insufficient milk (44.4%), child was still hungry after breastfeeding (37.5%), and the belief that the child was old enough to stop breastfeeding (32.9%). Conclusion Development of educational interventions are needed to improve breastfeeding exclusivity and raise women’s awareness of the importance of exclusive breastfeeding. Healthcare providers should help women gain confidence in their ability to produce enough milk to successfully continue breastfeeding.
Sex differences in the cardiorespiratory and hemodynamic response to exercise exist due to differences in heart size, blood volume, and hemoglobin mass, eliciting higher maximal oxygen uptake (VO2max) in men versus women. Data are equivocal whether sex differences in training responsiveness occur. This study investigated potential sex differences in the hemodynamic response (stroke volume (SV) and cardiac output (CO)) to high‐intensity interval exercise (HIIE). Habitually active men (n = 15) and women (n = 13) underwent VO2max testing, followed by three HIIE sessions consisting of the 4 × 4, 10 × 1, and reduced exertion high‐intensity training (REHIT), whose order was randomized. During exercise, oxygen uptake (VO2) and hemodynamic responses were determined. Results showed no sex difference in peak relative VO2 (p = 0.263), CO (p = 0.277), or SV (p = 0.116), although absolute values were higher in men (p < 0.05). Peak absolute (127.3 ± 20.6 vs. 115.2 ± 16.6 mL/beat, p = 0.004, d = 0.66) and relative SV (111.0 ± 15.5 vs. 100.7 ± 11.1% max, p = 0.005, d = 0.78) were higher with REHIT versus 4 × 4. No sex differences in mean relative VO2, CO, or SV occurred (p > 0.05). Data showed lower mean VO2 during REHIT versus 4 × 4 (59.3 ± 6.8 vs. 65.8 ± 5.8 %VO2max, p < 0.001, d = 1.05) and 10 × 1 (59.3 ± 6.8 vs. 69.1 ± 7.4 %VO2max, p < 0.001, d = 1.4). Mean CO was lower in REHIT than 10 × 1 (79.8 ± 8.6 vs. 84.0 ± 7.4% max, p = 0.012, d = 0.53). Previously reported differences in VO2max response to HIIE may not be due to unique hemodynamic responses.
The objective of this study was to measure particulate matter (PM) total loss rates in three older (1940s, 1960s, and 1980s) elevators in California during two phases and three low-cost intervention modes. Tracer gas decay and <2 μm aerodynamic diameter nontoxic NaCl particles (PM2) were used to calculate PM2 loss rates. The NaCl particles were considered surrogates for smaller particles carrying SARS-CoV-2. Empirical PM2 loss rates were paired with modeled dynamic scenarios to estimate SARS-CoV-2-relevant PM2 removal. Mean loss rates (hr-1) ranged from 1.8 to 184. Compared to a closed-door, stationary elevator, the moving elevators had a fourfold increased mean loss rate (hr-1), while an air cleaner in a stationary elevator increased the mean loss rates sixfold. In a dynamic particle removal simulation of a ten-story elevator, PM was removed 1.38-fold faster with an air cleaner intervention during bottom and top floor stops only (express ride) and 1.12-fold faster with an air cleaner during every other floor stops. The increase in removal rates due to the air cleaner was modest due to the higher moving and open-door removal rates, except during stationary phase. The half-life of PM2 particles in a stationary elevator after all passengers have left can be 8-12 minutes following a single emission and 2-5 minutes with an air cleaner. The low particle removal rate in the stationary elevator requires an intervention so that the particle removal rate will be high to eliminate infectious aerosol. If codes permit, keeping the door open when the elevator is stationary is most effective; otherwise, an air cleaner in a stationary elevator should be used. While an air cleaner is commonly seen as a substantial improvement in reducing potential virus concentration in air, in the moving elevator scenarios, the effect is quite modest. This paper provides empirical particle loss rates inside elevators, the effectiveness of air cleaners in a dynamic elevator space, two approaches to control infectious agents while the elevator is stationary, and support for a precautionary approach towards elevator use amidst a pandemic.
The paper examines the legal nature of the estoppel principle, applied both as a result of unfair actions of the party and because of the party’s inconsistent behavior. The paper analyzes the possibility of applying the German principle of protestatio facto contraria (objection to the actual expression of will) and compares estoppel and the continental law principle venire contra factum proprium.The study classifies the rules of law regulating the application of the estoppel principle; two categories of norms are distinguished, namely, the norms related to the prohibition of unfair actions and the norms aimed at preserving the contract. The author compares the norms of the Russian civil legislation regulating the application of the estoppel principle and highlights the conditions under which its application is allowed. The paper discusses the possibility of applying the principle of estoppel in the absence of the party’s intentions to harm the counterparty. The author analyzes the court practice related to the prohibition of contradictory behavior. In particular, the author analyzes legal disputes caused by the parties’ references to the non-conclusion or invalidity of the contract, as well as related to the inconsistent refusal of the party from the contract. Additionally, the author identified the circumstances to be proved when referring the parties to the need to apply the estoppel principle. Based on the results of the analysis, the author proposes options for improving legislative regulation of the application of the estoppel principle. In particular, the author proposes to introduce the following criteria for analyzing the need to apply the estoppel principle: the degree of validity and reasonableness of expectations of the counterparty’s behavior; analysis of the counterparty’s behavior; a causal relationship between an inconsistent behavior of the party and the damage caused to the relying party; the degree of damage caused to the party as a result of the counterparty’s unscrupulous behavior.
Porous asphalt mixtures are gaining popularity due to their ability to effectively drain surface water and mitigate traffic noise in regions with high rainfall. However, compared to conventional asphalt pavements, these types of pavements with high void content necessitate specific guidelines for achieving an optimal mix design. The performance characteristics of porous asphalt mixtures are notably influenced by the grading and composition of materials, especially with regards to their resistance to moisture damage. This study aimed to investigate the properties of porous asphalt mixtures using limestone and siliceous aggregates with varying gradations, while maintaining bitumen contents of 5% and 6%. In accordance with the regulations set forth by the National Center for Asphalt Technology, the findings indicate that siliceous-based aggregates exhibit improved void characteristics (increased by 3%) and permeability (increased by 11%). However, they also display reduced resistance to moisture-induced failures (decreased by 4%). On the other hand, adhering to the gradation recommendations provided by the National Asphalt Pavement Association guidelines, except for a slight decrease of 3% in moisture sensitivity, yields an overall enhancement of 25% in other performance characteristics. To analyze the data, statistical methods were employed, resulting in regression models with a minimum R ² value of 0.97. These models helped determine the optimal binder percentage for different aggregate types and gradations, providing valuable insights for practical implementation.
Although uniqueness has various definitions in the literature, the personal sense of uniqueness, defined as the perception of unconditional self-worth, contributes positively to mental health. Research has found that perceived responses to capitalization attempts and the sense of uniqueness are negatively associated with depression and positively associated with happiness. Our study was conducted with an emerging adult sample from various ethnicities (N = 557) and investigated the sense of uniqueness as the mediator of perceived responses to capitalization attempts in friendships and mental health. The models demonstrated that the correlations between perceived responses to capitalization attempts and both happiness and depression were mediated by the sense of uniqueness. The results were discussed by considering the role of uniqueness in the capitalization process. Also, suggestions for future research were provided.
Digestion is driven by digestive enzymes and digestive enzyme gene copy number can provide insights on the genomic underpinnings of dietary specialization. The "Adaptive Modulation Hypothesis" (AMH) proposes that digestive enzyme activity, which increases with increased gene copy number, should correlate with substrate quantity in the diet. To test the AMH and reveal some of the genetics of herbivory vs carnivory, we sequenced, assembled, and annotated the genome of Anoplarchus purpurescens, a carnivorous prickleback fish in the family Stichaeidae, and compared the gene copy number for key digestive enzymes to that of Cebidichthys violaceus, a herbivorous fish from the same family. A highly contiguous genome assembly of high quality (N50 = 10.6 Mb) was produced for A. purpurescens, using combined long-read and short-read technology, with an estimated 33,842 protein-coding genes. The digestive enzymes that we examined include pancreatic α-amylase, carboxyl ester lipase, alanyl aminopeptidase, trypsin, and chymotrypsin. Anoplarchus purpurescens had fewer copies of pancreatic α-amylase (carbohydrate digestion) than C. violaceus (1 vs. 3 copies). Moreover, A. purpurescens had one fewer copy of carboxyl ester lipase (plant lipid digestion) than C. violaceus (4 vs. 5). We observed an expansion in copy number for several protein digestion genes in A. purpurescens compared to C. violaceus, including trypsin (5 vs. 3) and total aminopeptidases (6 vs. 5). Collectively, these genomic differences coincide with measured digestive enzyme activities (phenotypes) in the two species and they support the AMH. Moreover, this genomic resource is now available to better understand fish biology and dietary specialization.
This paper considers the problem of kernel regression and classification with possibly unobservable response variables in the data, where the mechanism that causes the absence of information can depend on both predictors and the response variables. Our proposed approach involves two steps: First we construct a family of models (possibly infinite dimensional) indexed by the unknown parameter of the missing probability mechanism. In the second step, a search is carried out to find the empirically optimal member of an appropriate cover (or subclass) of the underlying family in the sense of minimizing the mean squared prediction error. The main focus of the paper is to look into some of the theoretical properties of these estimators. The issue of identifiability is also addressed. Our methods use a data-splitting approach which is quite easy to implement. We also derive exponential bounds on the performance of the resulting estimators in terms of their deviations from the true regression curve in general \(L_p\) norms, where we allow the size of the cover or subclass to diverge as the sample size n increases. These bounds immediately yield various strong convergence results for the proposed estimators. As an application of our findings, we consider the problem of statistical classification based on the proposed regression estimators and also look into their rates of convergence under different settings. Although this work is mainly stated for kernel-type estimators, it can also be extended to other popular local-averaging methods such as nearest-neighbor and histogram estimators.
Although students tend to dislike exams, tests—broadly defined in the present commentary as opportunities to practice retrieving to-be-learned information—can function as one of the most powerful learning tools. However, tests have a variety of attributes that affect their efficacy as a learning tool. For example, tests can have high and low stakes (i.e., the proportion of a student’s grade the exam is worth), vary in frequency, cover different ranges of course content (e.g., cumulative versus non-cumulative exams), appear in many forms (e.g., multiple-choice versus short answer), and occur before or after the presentation of what is to be learned. In this commentary, we discuss how these different approaches to test design can impact the ability of tests to enhance learning and how their use as instruments of learning—not just means of assessment—can benefit long-term learning. We suggest that instructors use frequent, low-stakes, cumulative exams and a variety of test formats (e.g., cued recall, multiple-choice, and true/false) and give students exams both prior to learning and following the presentation of the to-be-learned material.
Let $\ell $ be a prime number. The Iwasawa theory of multigraphs is the systematic study of growth patterns in the number of spanning trees in abelian $\ell $ -towers of multigraphs. In this context, growth patterns are realized by certain analogs of Iwasawa invariants, which depend on the prime $\ell $ and the abelian $\ell $ -tower of multigraphs. We formulate and study statistical questions about the behavior of the Iwasawa $\mu $ and $\lambda $ invariants.
For bilinguals, lexical access in one language may affect, or be affected by, activation of words in another language. Research to date suggests seemingly contradictory effects of such cross-linguistic influence (CLI): in some cases CLI facilitates lexical access while in others it is a hindrance. Here we provide a comprehensive review of CLI effects drawn from multiple disciplines and paradigms. We describe the contexts within which CLI gives rise to facilitation and interference and suggest that these two general effects arise from separate mechanisms that are not mutually exclusive. Moreover, we argue that facilitation is ubiquitous, occurring in virtually all instances of CLI, while interference is not always present and depends on levels of cross-language lexical competition. We discuss three critical factors – language context, direction, and modality of CLI – which appear to modulate facilitation and interference. Overall, we hope to provide a general framework for investigating CLI in future research.
Racial and ethnic disparities in STEM achievement are associated with weaker economic growth, greater social inequalities, and narrower parameters of scientific inquiry. Extant research suggests that undergraduate research experiences (URE) can reduce those disparities by enhancing perceptions of belonging and scientific self-efficacy among students from underrepresented groups. However, to date, very few studies have examined the relationship between URE and post-baccalaureate educational achievement gains among such students and those that have tend to be limited in terms of causal leverage and generalizability. In this study, we aim to make progress by analyzing data from the California State University system’s longstanding Louis Stokes Alliance for Minority Participation (CSU-LSAMP) program. Applying a quasi-experimental research design and drawing upon a large and representative sample of students whom we tracked over time, we observe that URE is strongly associated with post-baccalaureate enrollment and graduation in STEM disciplines among students from underrepresented backgrounds.
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Al-Mahmnur Alam
  • Department of Chemistry and Biochemistry
Alejandra Cox
  • Department of Economics
Amanda Fisher
  • Department of Biological Sciences
Huajun Yang
  • Department of Chemistry and Biochemistry
Long Beach, United States