Pepperdine University
  • Malibu, United States
Recent publications
Background: Anxiety disorders are common among adolescents. In high-income countries, anxiety is a known contributor to truancy and school refusal, but this association has been understudied in low- and middle-income countries (LMICs). Methods: We used complex samples analysis to examine the association between self-reported worry-induced insomnia (an indicator of anxiety) and unauthorized school absenteeism among 268,142 adolescents from 69 LMICs that participated in the Global School-based Student Health Survey (GSHS). Results: The median proportion of students who reported experiencing symptoms of anxiety most or all of the time during the previous year was 11.4% (range: 3.6%–28.2%); in 44 of the 69 countries, girls had a significantly higher prevalence of anxiety than boys. The percentage of students reporting school absence without permission during the past month was 30.2% (range: 14.7%–56.0%); in 40 countries, boys were significantly more likely than girls to report that they had missed school without permission in the past month. In 53 countries, adolescents who reported frequent anxiety were significantly more likely to miss school than adolescents reporting infrequent anxiety; in most of those countries, the association was significant for both girls and boys. Conclusion: School-based interventions that help children and adolescents learn how to manage stress and refer students with symptoms of psychiatric disorders to healthcare services that can provide formal diagnosis and clinical treatment may be useful for improving both mental health and school attendance, thus contributing to achievement of Sustainable Development Goals related to both health (SDG 3.4) and education (SDG 4.1).
In 2020, Bennett, Carrillo, Machacek and Sagan gave a polynomial generalization of the Narayana numbers and conjectured that these polynomials have positive integer coefficients for 1≤k≤n and for n≥1. In 2020, Sagan and Tirrell used a powerful algebraic method to prove this conjecture (in fact, they extend and prove the conjecture for more than just the type A case). In this paper we give a combinatorial proof of a formula satisfied by the Lucas-Narayana polynomials described by Bennett et al. This gives a combinatorial proof that these polynomials have positive integer coefficients. A corollary of our main result establishes a parallel theorem for the FiboNarayana numbers Nn,k,F, providing a combinatorial proof of the conjecture that these are positive integers for n≥1.
Studies are needed to understand the association between self-reported home smoking bans and objective measures of in-home smoking according to smokers’ ethnicity/nativity. Data came from a trial that used air particle monitors to reduce children’s secondhand smoke exposure in smokers’ households (N = 251). Linear regressions modeled (a) full home smoking bans by ethnicity/nativity, and (b) objectively measured in-home smoking events, predicted by main and interaction effects of self-reported home smoking bans and ethnicity/nativity. Among smokers reporting < a full ban, US-born and Foreign-born Latinos had fewer in-home smoking events than US-born Whites (p < 0.001). Participants who reported a full smoking ban had a similar frequency of smoking events regardless of ethnicity/nativity. Results indicate that self-reported home smoking bans can be used as a proxy for in-home smoking. Establishing smoking bans in the households of US-born White smokers has the largest impact on potential exposure compared to other ethnicity/nativity groups.
Ticks are the most important vectors of zoonotic disease-causing pathogens in North America and Europe. Many tick species are expanding their geographic range. Although correlational evidence suggests that climate change is driving the range expansion of ticks, experimental evidence is necessary to develop a mechanistic understanding of ticks’ response to a range of climatic conditions. Previous experiments used simulated microclimates, but these protocols require hazardous salts or expensive laboratory equipment to manipulate humidity. We developed a novel, safe, stable, convenient, and economical method to isolate individual ticks and manipulate their microclimates. The protocol involves placing individual ticks in plastic tubes, and placing six tubes along with a commercial two-way humidity control pack in an airtight container. We successfully used this method to investigate how humidity affects survival and host-seeking (questing) behavior of three tick species: the lone star tick ( Amblyomma americanum ), American dog tick ( Dermacentor variabilis ), and black-legged tick ( Ixodes scapularis ). We placed 72 adult females of each species individually into plastic tubes and separated them into three experimental relative humidity (RH) treatments representing distinct climates: 32% RH, 58% RH, and 84% RH. We assessed the survival and questing behavior of each tick for 30 days. In all three species, survivorship significantly declined in drier conditions. Questing height was negatively associated with RH in Amblyomma , positively associated with RH in Dermacentor , and not associated with RH in Ixodes . The frequency of questing behavior increased significantly with drier conditions for Dermacentor but not for Amblyomma or Ixodes . This report demonstrates an effective method for assessing the viability and host-seeking behavior of tick vectors of zoonotic diseases under different climatic conditions.
Aiming at protecting and enhancing the quality of life of mid-lower income groups, China gradually implements the construction of public rental housing projects across the country. This paper takes Beijing as an example to analyse the potential impact of public rental housing on the city by constructing charts, which cover three aspects. The main findings are the creation of a large number of public rental housing units can attract an influx of high-quality talent, yet it is also found that while public rental housing can alleviate the pressure on the property expenditure of this group of people to a certain extent, it does not have a significant impact on their consumption expenditure due to the uncertainty of their future income. Finally, some suggestion on the construction and management of public rental housing are raised to improve the existing policy. KeywordsPublic rental housingConsumption expenditureTalent introduction
Abstract This study presents an environmentally contingent view of CEO core self‐evaluations (CSE) and the effects on strategic risk taking. Drawing on upper echelons theory and approach‐avoidance theory, we propose that high CSE CEOs are responsive to rather than disregard environmental cues and pursue strategic risks that enable the firm to capitalize on competitive opportunities while refraining from risks not suited to the external environment. Focusing on two forms of strategic risk—resource allocation risk taking and strategic nonconformity—we develop hypotheses examining the contingencies across levels of environmental concentration, dynamism, and munificence. We test our hypotheses on a panel of 106 CEOs from publicly traded US companies over 1998‐2004 using historiometric analyses. Supporting our hypotheses, findings indicate that the effects of CEO CSE on resource allocation risk taking and strategic nonconformity are contingent on industry concentration and environmental dynamism. Findings advance the understanding of CEO’s positive self‐regard.
The authors propose a strategy to help event planners pivot and adjust to the post-COVID world. This involves the use of social media and sales force automation (SFA). The authors explain how both of these can be accomplished in a low cost, easy to learn and use manner by adopting LinkedIn. The authors also present three tools that will help the event planner assess if they and their personnel are ready to make such a change. The authors conclude with a set of managerial imperatives that include not only how to be proactive and competitive but also the operational adjustments that will be necessary for the mode of operation, the reach of the planner, how online presence and content will drive awareness, the role and definition of personnel, how client relationships are conducted, and how the different facets of the event itself will change.
As a new generation enters the workforce, it is important to understand the ethical concerns of these emerging professionals and future leaders. Crucially, because forces such as technology, globalization, and social responsibility are transforming the business environment. The present study defines ethical concerns as topics of ethics that are important to oneself that are influenced by the social context and affect attitudes and behaviors. Inspired by past studies and trends, this research examines a four-decade historical perspective of ethical concerns of college students in the United States. Our findings indicate that the foci of concern for business-related ethical issues among incoming professionals have significantly shifted – focusing more on environmental, collective, and corporate social responsibility concerns of bettering society, but less on ethical standards meeting the needs of organizations. Of cautionary note, incoming professionals feel increased pressure to act unethically and to overlook ethical concerns related to application of new technologies in order to succeed. Implications for theory and practice are discussed.
The purpose of the current study was to assess the effects of acute and short-term nitrate (NO3−)-rich beetroot juice (BR) supplementation on performance outcomes and muscle oxygenation during bench press and back squat exercise. Fourteen recreationally active males were assigned in a randomized, double-blind, crossover design to supplement for 4 days in two conditions: (1) NO3−-depleted beetroot juice (PL; 0.10 mmol NO3− per day) and (2) BR (11.8 mmol NO3− per day). On days 1 and 4 of the supplementation periods, participants completed 2 sets of 2 × 70%1RM interspersed by 2 min of recovery, followed by one set of repetitions-to-failure (RTF) at 60%1RM for the determination of muscular power, velocity, and endurance. Quadriceps and pectoralis major tissue saturation index (TSI) were measured throughout exercise. Plasma [NO3−] and nitrite ([NO2−]) were higher after 1 and 4 days of supplementation with BR compared to PL (p < 0.05). Quadriceps and pectoralis major TSI were not different between conditions (p > 0.05). The number of RTF in bench press was 5% greater after acute BR ingestion compared to PL (PL: 23 ± 4 vs. BR: 24 ± 5, p < 0.05). There were no differences between BR and PL for RTF for back squat or power and velocity for back squat or bench press (p > 0.05). These data improve understanding on the ergogenic potential of BR supplementation during resistance exercise.
Wearable devices represent one of the most popular trends in health and fitness. Rapid advances in wearable technology present a dizzying display of possible functions: from thermometers and barometers, magnetometers and accelerometers, to oximeters and calorimeters. Consumers and practitioners utilize wearable devices to track outcomes, such as energy expenditure, training load, step count, and heart rate. While some rely on these devices in tandem with more established tools, others lean on wearable technology for health-related outcomes, such as heart rhythm analysis, peripheral oxygen saturation, sleep quality, and caloric expenditure. Given the increasing popularity of wearable devices for both recreation and health initiatives, understanding the strengths and limitations of these technologies is increasingly relevant. Need exists for continued evaluation of the efficacy of wearable devices to accurately and reliably measure purported outcomes. The purposes of this review are (1) to assess the current state of wearable devices using recent research on validity and reliability, (2) to describe existing gaps between physiology and technology, and (3) to offer expert interpretation for the lay and professional audience on how best to approach wearable technology and employ it in the pursuit of health and fitness. Current literature demonstrates inconsistent validity and reliability for various metrics, with algorithms not publicly available or lacking high-quality validation studies. Advancements in wearable technology should consider standardizing validation metrics, providing transparency in used algorithms, and improving how technology can be tailored to individuals. Until then, it is prudent to exercise caution when interpreting metrics reported from consumer-wearable devices.
While recent studies have examined the effects of viewing body-positive social media content on body appreciation and satisfaction in young adult women, research has yet to include older adult women. The current study assessed the effects of viewing body-positive Instagram content on body image in 205 adult women (18-76 years old) who were randomly assigned to view either body-positive, thin-ideal, or appearance-neutral Instagram content. Our findings demonstrated that exposure to body-positive Instagram content resulted in greater levels of body appreciation and body satisfaction compared to exposure to thin-ideal and neutral Instagram content, while no significant differences were found between any of the conditions on self-objectification. Finally, age was only a significant moderator for one variable (self objectification) and condition (thin ideal), indicating that exposure to body-positive social media content may improve levels of body appreciation and satisfaction in adult women, regardless of age.
Entrepreneurial ecosystems (EE) are composed not only of startups but also the organizations that support them. Theory has been ambivalent about whether an EE is spatially bounded or includes distant organizations. This exploratory study uses a time series of all Internet industry initial public offerings (IPO) to explore the locational changes not only of startups but also four key EE service providers: lawyers, investment bankers, venture capitalists, and board directors. We find that while the startups became only slightly more concentrated, the EE service providers concentrated more rapidly, as an industry center in Silicon Valley emerged. Our results suggest that over the industry life cycle, industry knowledge exhibits a tendency to spatially concentrate, and this results in a concentration of industry-specific EE service providers that is even greater than the more gradual concentration of startups. As a result, startups, wherever they are located, increasingly source EE services from the industrial knowledge concentration.
Background and purpose: Accurate delineation of the urethra is a prerequisite for urethral dose reduction in prostate radiotherapy. However, even in MR-guided radiation therapy (MRgRT), consistent delineation of the urethra is challenging, particularly in online adaptive radiotherapy. This paper presented a fully automatic MRgRT-based prostatic urethra segmentation framework. Materials and methods: Twenty-eight prostate cancer patients were included in this study. In-house 3D HASTE and TSE sequences were used to image the Foley-free urethra on a 0.35T MRgRT system. The segmentation pipeline uses 3D nnU-Net as the base and innovatively combines ground truth and its corresponding radial distance (RD) map during training supervision. Additionally, we evaluate the benefit of incorporating a convolutional long-short term memory (LSTM-Conv) layer and spatial recurrent layer (RCL) into nnU-Net. A novel slice-by-slice simple exponential smoothing (SEPS) method specifically for tubular structures was used to post-process the segmentation results. Results: The experimental results show that nnU-Net trained using a combination of Dice, cross-entropy and RD achieved a Dice score of 77.1±2.3% in the testing dataset. With SEPS, Hausdorff distance (HD) and 95% HD were reduced to 2.95±0.17 mm and 1.84±0.11 mm, respectively. LSTM-Conv and RCL layers only minimally improved the segmentation precision. Conclusion: We present the first Foley-free MRgRT-based automated urethra segmentation study. Our method is built on a data-driven neural network with novel cost functions and a post-processing step designed for tubular structures. The performance is consistent with the need for online and offline urethra dose reduction in prostate radiotherapy. This article is protected by copyright. All rights reserved.
Advertisers and marketers increasingly adopt and invest in audiovisual formats for their communications. In contrast, academic researchers often rely on static visual stimuli to test advertising- and marketing-related research questions. In this research note, we discuss whether and how academic research could benefit from the ability to develop and use dynamic audiovisual stimuli and we consider the validity-related trade-offs inherent in their use. We first outline the components researchers should consider in constructing dynamic audiovisual stimuli. Then, in an attempt to reduce barriers to creation of dynamic audiovisual stimuli in advertising research, we review tools researchers can use to design realistic dynamic stimuli. We conclude with ways in which the use of dynamic stimuli can open new research approaches, thus expanding advertising-related theory.
This paper takes as its starting point an important conversation held between Thomas Hardy and Leslie Stephen in 1875 in which they discussed the “unreality of time” (Maitland 1906 Maitland, Frederic. 1906. The Life and Letters of Leslie Stephen. London: Duckworth. [Google Scholar], 203). This idea informs Hardy’s (1873 Hardy, Thomas. (1873) 2009. A Pair of Blue Eyes, edited by Alan Manford. Oxford: Oxford University Press. [Google Scholar]) novel, A Pair of Blue Eyes, in which the amateur geologist Henry Knight hangs from a cliff and before him flashes a vision of deep time, which culminates in an eye-to-eye encounter with a trilobite. Several critics have argued for Leslie Stephen’s “A Bad Five Minutes in the Alps” (1872 Stephen, Leslie. 1872. “A Bad Five Minutes in the Alps.” Fraser’s Magazine (New Series) 6 (November): 545–560. [Google Scholar]), published just weeks before, as a source of inspiration for Hardy’s scene. I investigate these claims, and argue that Gideon Mantell’s Wonders of Geology (1848 Mantell, Gideon. (1838) 1848. The Wonders of Geology. 6th ed. London: Henry G. Bohn. Beinecke Library, Yale University, Purdy 128. [Google Scholar]) was a greater influence. Drawing on the work of Patricia Ingham and Adelene Buckland, I consider the differences between these texts, and explore the implications of Hardy’s removing the gaze of Mantell’s “higher intelligence” and replacing his teleological view of time with a backwards slide down the evolutionary scale. This prefigured Thomas Henry Huxley’s fear that with the cooling of the sun, humankind would eventually devolve into “low” and “simple” organisms “such as the Diatom of the arctic and antarctic ice” (1894 Huxley, Thomas Henry. 1894. “The Struggle for Existence in Human Society.” In Evolution and Ethics, 195–236. London: Macmillan. [Google Scholar], 191). This paper also draws on Hardy’s copy of The Wonders of Geology, now in the Beinecke, and contested questions around its provenance. Finally, I conclude that this scene raises questions of scale that are never fully resolved and that these questions haunt the rest of Hardy’s oeuvre.
Although the practitioner and the academic literatures both note the importance of ethno-racial diversity in the nonprofit sector, we pursue a better understanding of this sector’s ethno-racial diversity dynamics by exploring the drivers of ethno-racial diversity at multiple organizational hierarchy levels—boards of directors, executive staff teams, and full-time staff. Using data from nonprofit organizations participating in Candid’s Diversity, Equity, and Inclusion initiative, we find evidence that upward mobility for ethno-racial minority group members remains limited. Our findings also indicate a positive relationship between ethno-racial diversity in a nonprofit’s local community and ethno-racial diversity at each organizational hierarchy level. This relationship is partially mediated by the political liberalness of the local community, with the strongest mediating effects at the board of directors and executive staff organizational levels. This partial mediation suggests that the local environment’s tolerance of societal hierarchies and unequal outcomes may be related to nonprofit organizational diversity, equity, and inclusion efforts.
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3,264 members
Edward Shafranske
  • The Graduate School of Education and Psychology
Kathleen A Eldridge
  • The Graduate School of Education and Psychology
David W. Foy
  • The Graduate School of Education and Psychology
Rodney L Honeycutt
  • Division of Natural Science
Adel C Najdowski
  • The Graduate School of Education and Psychology
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