California State University, Dominguez Hills
  • Carson, California, United States
Recent publications
This study empirically examines the impact of geographic customer diversification on inventory efficiency and proposes a customer-country diversification strategy as a central element of U.S. manufacturing firms’ effort to transform their global supply chains in the aftermath of the COVID-19 pandemic. Using industry-level data during the pre-pandemic period (2003-2018) and the COVID-19 pandemic, this study finds that a geographically diversified customer base significantly reduced inventory efficiency during the pre-pandemic period, but increased inventory efficiency during the COVID-19 pandemic. Our finding suggests that U.S. manufacturing firms may be able to reduce negative impacts on inventory in a global pandemic and achieve greater inventory efficiency if they can target global customer bases with demand characteristics less correlated with U.S. domestic demand.
The importance of cryptocurrency to the global economy is increasing steadily, which is evidenced by a total market capitalization of over $2.18T as of December 17, 2021, according to coinmarketcap.com (Coin, 2021). Cryptocurrencies are too confusing for laymen and require more investigation. In this study, we analyze the impact that the effective reproductive rate, an epidemiological indicator of the spread of COVID-19, has on both the price and trading volume of eight of the largest digital currencies—Bitcoin, Ethereum, Tether, Ripple, Litecoin, Bitcoin Cash, Cardano, and Binance. We hypothesize that as the rate of spread decreases, the trading price of the digital currency increases. Using Generalized Autoregressive Conditional Heteroskedasticity models, we find that the impact of the spread of COVID-19 on the price and trading volume of cryptocurrencies varies by currency and region. These findings offer novel insight into the cryptocurrency market and the impact that the viral spread of COVID-19 has on the value of the major cryptocurrencies.
This paper assesses the impact of the Colombian internal armed conflict on local development processes and deforestation during 2000–2018. The paper develops a theoretical framework of the deforestation process, as determined by the spatiotemporal patterns of socio-economic and conflict related variables. These determinants are examined using a system of spatial dynamic panels by land-use activity, and emphasizing interactions and spatiotemporal lags. The theoretical approach is innovative and applicable to other cases where political, economic and ideological interests interact in deforestation processes. In addition, the methodological structure of our spatial panels allows us to determine the effect of armed conflict agents’ and socio-economic structures, combined and in isolation. Our results formally verify that different armed actors’ strategies and ideologies, determine different and contrasting spatiotemporal patterns of deforestation/conservation, in the context of structural socio-economic determinants in Colombia. We argue about the need of context-specific modelling in any microeconomic or agent-based analysis of deforestation.
Protracted droughts lasting years to decades constitute severe threats to human welfare across the Indian subcontinent. Such events are, however, rare during the instrumental period ( ca . since 1871 CE). In contrast, the historic documentary evidence indicates the repeated occurrences of protracted droughts in the region during the preinstrumental period implying that either the instrumental observations underestimate the full spectrum of monsoon variability or the historic accounts overestimate the severity and duration of the past droughts. Here we present a temporally precise speleothem-based oxygen isotope reconstruction of the Indian summer monsoon precipitation variability from Mawmluh cave located in northeast India. Our data reveal that protracted droughts, embedded within multidecadal intervals of reduced monsoon rainfall, frequently occurred over the past millennium. These extreme events are in striking temporal synchrony with the historically documented droughts, famines, mass mortality events, and geopolitical changes in the Indian subcontinent. Our findings necessitate reconsideration of the region’s current water resources, sustainability, and mitigation policies that discount the possibility of protracted droughts in the future.
We consider the problem of SDN flow optimization in the presence of a dynamic probabilistic link failures model. We introduce a metric for path risk, which can change dynamically as network conditions and failure probabilities change. As these probabilities change, the end-to-end path survivability probability may drop, i.e., its risk may rise. The main objective is to reroute at-risk end-to-end flows with the minimum number of flow operation so that a fast flow recovery is guaranteed. We provide various formulations for optimizing network risk versus operational costs and examine the trade-offs in flow recovery and the connections between operational cost, path risk, and path survival probability. We present our suboptimal dynamic flow restoration methods and evaluate their effectiveness against the Lagrangian relaxation approach. Our results show a significant improvement in operational cost against a shortest-path approach.
This paper examines the contemporary meanings and functions of self-Orientalism in the Bosnian context by analyzing Jasmila Žbanić’s film, Quo Vadis, Aida (2020). The issue of self-Orientalism entails a double intrigue at the individual and collective levels: first, why Bosnian cultural producers (the ‘Orientalized’) replicate Orientalism; and second, why Orientalism, in its various forms, proliferates in Balkans despite the region’s own marginalized position. Examining Quo Vadis Aida both within Bosnian’s specific context and as part of a global phenomenon of cinematic self-Orientalism or autoexoticism, this paper argues that the film self-Orientalizes in an effort to meet contemporary viewers’ expectations for facile resolutions to imperialist Orientalism, as well as to improve the film’s marketability with Western audiences. Applying Laura Doyle’s framework of ‘inter-imperiality’ we examine how Quo Vadis, Aida ‘writes back’ to multiple empires by tracing Orientalism’s trajectories – from Ottoman Empire to the Austro-Hungarian and modern-day Holland – and by weaving the lingering effects of imperialism from before the arrival Ottomans to Bosnia in Middle Ages to the present. The paper argues that the film reveals the extent of globalist anxiety that motivates producers’ artistic imagination and reflects colonial phantasies that promote stereotyped representation of the Balkans.
We are not aware of any validated sexual health communication scales for use with young men who have sex with men (YMSM). We used data from an HIV prevention study in Lebanon with 226 YMSM aged 18–29 to assess the psychometric characteristics of our scale, Judgmental Communication with Peers about Sex (JCPS). The construct validity of the JCPS scale was supported by it being negatively correlated with general social support, percentage of alters perceived to be supportive, and the percentage of peers who are perceived to use condoms. The scale was positively correlated with gay-related discrimination, feeling part of the gay community, and gay social integration. These findings reflect a reliable, valid measure to assess judgmental sexual health communication between YMSM.
The purpose of this cross-sectional study is to examine the causal relationship of maternal education and infants' health outcomes. Using birth certificate data over the years 1970–2004 and exploiting the space-time variation in Minimum Dropout Age laws to solve the endogeneity of education, we find a sizeable effect of mothers' education on their birth outcomes. An additional year of maternal education is associated with a reduction in incidences of low birth weight and preterm birth by 15.2 and 12.7 percent, respectively. The estimates are robust across various specifications and even when allowing mothers’ cohort-of-birth to vary across regions. The results suggest that the candidate mechanisms of impact include improvements in timing, quantity, and quality of prenatal care, lower negative health behavior during pregnancy such as smoking and drinking, and higher spousal education.
We examine whether and how auditors incorporate rollover risk in assessing a client’s risk. Rollover risk is the risk associated with long-term debt maturing in 1 year, which has to be refinanced or settled shortly. Debt has two counteracting effects on firms’ riskiness: increased liquidity risk and increased monitoring. The finance literature suggests that rollover risk is an apparent risk factor because it results in high liquidity risk but only a weak (or limited) monitoring benefit. Consistent with that literature, we show that auditors increase audit fees, exhibit a higher likelihood of issuing a going-concern opinion, and terminate relations with their clients more frequently as rollover risk increases. Our study is the first in the audit research literature to document that auditors factor rollover risk in their pricing, going concern, and client portfolio decisions.
Encouraging consumers to adopt a new shopping model is always challenging for a retailer. With the fierce competition in the retail industry, retailers aim to actively reach more consumers, especially on the internet. The Try-Before-You-Buy (TBYB) e-commerce shopping model has been emerging and rapidly developing recently. This study examines the antecedents of consumers’ acceptance of the TBYB model. We find that tailoring to consumers’ preferences—namely, implementing a customization strategy—is beneficial to enhance consumers’ perceived quality of the TBYB model, however, it also increases their perceived risk of the model. Additionally, offering a flexible forward transaction process is more important than the backward transaction flexibility because while both increase consumers’ perceived quality, only the forward transaction flexibility reduces consumers’ perceived risk of the TBYB model. Further, we find while the perceived quality is a facilitator for consumers to have the intention to accept the TBYB model, higher perceived risk is not a preventer. This reveals the asymmetric role of consumers’ perceived quality and perceived risk in generating their TBYB model acceptance intention. Our study helps retailers to implement the corresponding improvement policies and designs to better optimize the operations of the TBYB model.
Functional trait diversity determines if ecosystem processes are sensitive to shifts in species abundances or composition. For example, trait variation suggests detritivores process detritus at different rates and make different contributions to whole-assemblage processing, which could be sensitive to compositional shifts. Here, we used a series of microcosm experiments to quantify species-specific coarse and fine particulate organic matter (CPOM and FPOM) processing for ten larval caddisfly species and three non-caddisfly species in high-elevation wetlands. We then compared trait-based models including life history, dietary, and extrinsic traits to determine which traits explained interspecific variation in detritus processing. Finally, we compared processing by mixed caddisfly assemblages in microcosms and natural ponds to additive predictions based on species-specific processing to determine if single-species effects are additive in multi-species assemblages. We found considerable interspecific variation in biomass-specific CPOM (13-fold differences) and FPOM (8-fold differences) processing. Furthermore, on a mass-specific basis, amphipods, chironomids, and caddisflies processed similar amounts of detritus, suggesting non-shredder taxa could process more than previously recognized. Trait models including dietary percent detritus, development rate, body size, and wetland hydroperiod explained 81 and 57% of interspecific variation in CPOM and FPOM processing, respectively. Finally, species-specific additive predictions were strikingly similar to mixed-assemblage processing in microcosms and natural ponds, with the largest difference being a 15% overestimate. Thus, additivity of species-specific processing suggests single-species rates may be useful for understanding functional consequences of shifting assemblages, and a trait-based approach to predicting species-specific processing could support generating additive predictions of whole-assemblage processing.
1. Anthropogenic nitrogen (N) deposition exerts profound influence on the composition and function of native ecosystems, commonly resulting in reduced plant richness and increases in nonnative plant invasion. Identifying differences in plant N responses and functional traits could help to explain the ongoing invasion and biological impoverishment of ecosystems subject to N deposition. 2. We compared the growth, emergence phenology, and functional traits of thirty native and invasive annual plant species under high and low N availability, with the goal of evaluating if invasives exhibit functionally dissimilar responses to N compared to the native species they displace. 3. Invasives grew larger than natives, especially under increased N availability. Overall, invasives and natives did not differ in emergence phenology. However, these groups of species differed in relationships between growth and days to emergence, and N addition further strengthened these differences; invasives consistently grew larger than natives that emerged around the same time, while natives showed a strong negative effect of delayed emergence on plant growth. 4. Relative N responses for measures of plant growth and allocation did not differ between native and invasive species, but invasives exhibited greater plasticity in physiological traits. This included significantly lower leaf N content, higher CN ratios, and greater water‐use efficiency (WUE) in plants grown under high N. Invasives also showed functionally different patterns of growth and water use. Across species, invasives showed a positive relationship between shoot growth and WUE. Native species showed a tradeoff between root allocation and WUE, while invasives displayed high values for WUE even despite reduced root:shoot ratios under high N. 5. Our results highlight the ability of invasives to rapidly accrue biomass, disproportionately benefit from early emergence and N addition, and use water efficiently despite rapid growth. Natives, on the other hand, pay a higher cost for delayed emergence and may experience tradeoffs between growth and water‐use. The more pronounced functional differences between natives and invasives observed under high N likely play an important role in driving invasion and reduced species diversity under N enrichment. These differences could be used to inform successful management strategies for N‐impacted and water‐limited ecosystems.
Over two hundred billion black soldier flies (BSF, Hermetia illucens (Diptera: Stratiomyidae)) are reared annually across the globe, with the industry projected to grow substantially in the coming decade. Black soldier flies are being actively explored across the globe for use as livestock feed; fishmeal replacements; biodiesel; human, animal, and food waste management; and even sustainable human protein. Despite the huge number of individual insects reared and interest in BSF welfare by numerous producers and academics, there is no paper that considers the species-specific welfare of BSF in farmed conditions. We review factors that relate to BSF welfare in commercial rearing facilities, including: diseases/parasites, abiotic conditions (temperature, humidity/moisture, substrate aeration, light, pupation substrates, and adult spatial needs), adult and larval nutritional considerations, injury and crowding, handling-associated stress, selective breeding and genetic modification, environmental contaminants, and slaughter methods. We conclude with a discussion of the most pressing welfare concerns for the industry, recommendations for altering the conditions that give rise to them, and suggestions for future research directions that would lend valuable insights to BSF welfare. While this summary is BSF-centric, the core topic of animal welfare applies to all insect models currently, or in the future, produced as food and feed.
Prolung Khmer (ព្រលឹងខ្មែរ , meaning “Khmer Soul” or “Khmer Spirit”), is a culturally salient ideological discourse found in modern Cambodian culture in the homeland and the diaspora. Prolung Khmer draws on symbols and practices from Cambodia’s 2000-year cultural heritage, linking Khmer history, religion, language, the arts, and socio-political relationships in an essentialized ideology of Khmer culture. Using a genealogical analysis, this article traces the historical development of Prolung Khmer from earliest times to the present with examples from Cambodia and the diaspora. We argue that through its use, Prolung Khmer delineates, historicizes, and naturalizes what it means to be Khmer in the homeland and the diaspora.
Increased mass shootings and terrorist activities severely impact society mentally and physically. Development of real-time and cost-effective automated weapon detection systems increases a sense of safety in public. Most of the previously proposed methods were vision-based. They visually analyze the presence of a gun in a camera frame. This research focuses on gun-type (rifle, handgun, none) detection based on the audio of its shot. Mel-frequency-based audio features have been used. We compared both convolution-based and fully self-attention-based (transformers) architectures. We found transformer architecture generalizes better on audio features. Experimental results using the proposed transformer methodology on audio clips of gunshots show classification accuracy of 93.87%, with training loss and validation loss of 0.2509 and 0.1991, respectively. Based on experiments, we are convinced that our model can effectively be used as both a standalone system and in association with visual gun-detection systems for better security.
The theorization of multimodality in academic scholarship is disconnected from how it is conceptualized by children. To bridge this gap, we analyzed 75 interviews with children about their digital video making. Analysis of their responses demonstrates children's socially-embedded, age-specific understandings of how modes operate, as well as when and why to employ them. In many cases, children's ideas ran counter to formal semiotic grammars and metalanguages of design. Bridging Systemic Functional Linguistics and social semiotics approaches with work in transliteracies, we argue for the need to advance age-centric social semiotic theories that center children's voices, purposes, and capacity to generate theory.
Recognizing early cardiac sarcoidosis (CS) imaging phenotypes can help identify opportunities for effective treatment before irreversible myocardial pathology occurs. We aimed to characterize regional CS myocardial remodeling features correlating with future adverse cardiac events by coupling automated image processing and data analysis on cardiac magnetic resonance (CMR) imaging datasets. A deep convolutional neural network (DCNN) was used to process a CMR database of a 10-year cohort of 117 consecutive biopsy-proven sarcoidosis patients. The maximum relevance − minimum redundancy method was used to select the best subset of all the features—24 (from manual processing) and 232 (from automated processing) left ventricular (LV) structural/functional features. Three machine learning (ML) algorithms, logistic regression (LogR), support vector machine (SVM) and multi-layer neural networks (MLP), were used to build classifiers to categorize endpoints. Over a median follow-up of 41.8 (inter-quartile range 20.4–60.5) months, 35 sarcoidosis patients experienced a total of 43 cardiac events. After manual processing, LV ejection fraction (LVEF), late gadolinium enhancement, abnormal segmental wall motion, LV mass (LVM), LVMI index (LVMI), septal wall thickness, lateral wall thickness, relative wall thickness, and wall thickness of 9 (out of 17) individual LV segments were significantly different between patients with and without endpoints. After automated processing, LVEF, end-diastolic volume, end-systolic volume, LV mass and wall thickness of 92 (out of 216) individual LV segments were significantly different between patients with and without endpoints. To achieve the best predictive performance, ML algorithms selected lateral wall thickness, abnormal segmental wall motion, septal wall thickness, and increased wall thickness of 3 individual segments after manual image processing, and selected end-diastolic volume and 7 individual segments after automated image processing. LogR, SVM and MLP based on automated image processing consistently showed better predictive accuracies than those based on manual image processing. Automated image processing with a DCNN improves data resolution and regional CS myocardial remodeling pattern recognition, suggesting that a framework coupling automated image processing with data analysis can help clinical risk stratification.
Alterations to ratios of protein and fiber in an organism's diet have been shown to structurally and functionally alter its individual digestive physiology. However, it is unclear how these dietary changes may affect phenotypic changes across generations. We utilized feeding trials, morphological analyses, enzyme activities, and 16S rRNA sequencing of the gut microbiome of zebrafish (Danio rerio) to determine how variations to fiber and protein concentrations, kept consistent across sequential generations, affect phenotypic changes. Our results show that Parental (P) and first generation (F1) fish did not differ from each other in terms of their intestine length, intestine mass, enzyme activity levels, and microbial community composition for any of the three experimental diets (high-protein/low-fiber, moderate-protein/fiber, and low-protein/high-fiber). However, each of the three experimental diets for the P and F1 fish, as well as the ancestral diet fish, did have distinct microbial community structure from one another. This indicates that there is a strong dietary effect on digestive physiology and gut microbial community and that these effects are consistent when the diet is kept homogenous across generations.
It is quite common to find that formal and informal sectors compete in the waste electrical and electronic equipment (WEEE) recycling markets in developing countries. The formal sector consists of recyclers with dismantling qualifications, while the informal sector includes recyclers without qualifications. The two sectors compete on the used products' acquisition quantities which depend on both the acquisition prices and collection services. By constructing two-stage game models, the paper studies the two sectors’ competitive strategy, i.e., focusing on higher price or better service. We also examine how subsidies on the formal sector affect its decisions under two schemes of subsidies, namely, subsidy on acquisition quantity and subsidy on acquisition cost. The social welfare under two schemes of subsidies is compared under the same budget. Results show that as the collection cost of the formal sector decreases, the formal sector will adopt the service strategy by investing in its collection service, even at a cost disadvantage compared with the informal sector, while the informal sector will lower service level and raise acquisition price. A rise in subsidy level will also encourage the formal sector to use the service strategy.
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Elwin Tilson
  • Division of Health Sciences
Matt Mutchler
  • Department of Sociology
István Kovanecz
  • Department of Biology
Mojtaba Kamyab
  • Orthotics & Prosthetics
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