City University of New York City - Lehman College
Recent publications
This study shows that capital structure choices of US corporations are interdependent across time. We follow a two-step estimation approach. First, using a large cross-section of firms we estimate year-by-year average capital structure choices, i.e., the average firm’s percentage of new funding that is secured through debt, its term composition, and the percentage of new equity represented by retained earnings. Second, these time series are included in a Factor Augmented Vector Autoregressive model in which three factors representing real economic activity, expected future funding conditions, and prices, are included. We test for the interdependence between optimal capital structure decisions and for the influence exerted by macroeconomic conditions on these decisions. Results show there is a hierarchical order in which firms make capital structure decisions. They first decide on the share of debt out of total new funding they will hire. Conditional on this they decide on the term of their debt and on their earnings retention policy. Of outmost importance, macroeconomic factors are key for making capital structure decisions.
Let A\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\mathcal {A}}$$\end{document} be a class of algebras with I,A∈A\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$I, A \in {\mathcal {A}}$$\end{document}. We interpret the lattice-theoretic “strictly meet irreducible/cover” situation B<C\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$B < C$$\end{document} in lattices of the form SA(I,A)\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$S_{{\mathcal {A}}}(I,A)$$\end{document} of all subalgebras of A containing I, where we call such B<C\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$B < C$$\end{document} a minimum proper extension (mpe), and show that this means B is maximal in SA(I,A)\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$S_{{\mathcal {A}}}(I,A)$$\end{document} for not containing some r∈A\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$r \in A$$\end{document} and C is generated by B and r. For the class G\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\mathcal {G}}$$\end{document} of groups, we determine the mpe’s in SG({0},Q)\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$S_{{\mathcal {G}}}(\{0\},{\mathbb {Q}})$$\end{document} using invariants of Beaumont and Zuckerman and show that these (plus utilization of a Hamel basis) determine the mpe’s in SG({0},R)\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$S_{{\mathcal {G}}}(\{0\},{\mathbb {R}})$$\end{document}. Finally, we show that the latter yield some (not all) of the minimum proper essential extensions in W∗\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\mathbf {W}^{*}$$\end{document}, the category of Archimedean ℓ\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\ell $$\end{document}-groups with strong order unit and unit-preserving ℓ\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\ell $$\end{document}-group homomorphisms.
We study volatility spillovers between the corporate sector’s and Latin American countries’ CDS. Daily data from 14 October 2006 to 23 August 2021 are employed. Spillovers are computed both for the raw data and for filtered series, which factor out the effect of global common factors on the various CDS series. Results indicate that most spillovers occur within groups. However, considerable spillovers are also registered from LAC sovereigns to corporations and vice versa. Interesting differences are encountered between filtered and unfiltered data. Specifically, spillovers from countries to corporations are overestimated (in about 4.3% points) and spillovers from corporations to sovereigns are underestimated (in about 5.8% points) when unfiltered data is used. This result calls for a revision of results obtained from studies that do not consider the role of global common factors on system spillovers. Like in most related studies, spillovers show considerable time-variation, being larger during times of financial or economic distress. When looking at total system spillovers over time, those corresponding to unfiltered series are always larger than those corresponding to filtered series. The difference between the two time-series is largest in times of distress, indicating that global factors play a major role in times of crises.
Mental health concerns have increased in prevalence since the beginning of the COVID-19 pandemic. Many turn to online resources for relevant information. The purpose of this study is to describe the availability of mental health information on YouTube, and to assess the relevance of the videos’ content in relation to the actual need of the population. The 100 most-watched YouTube videos in English resulting from a YouTube search of “COVID-19” and “mental health” were evaluated. Of mental health conditions, anxiety and depression were mentioned in over 50% of the videos. A positive correlation was found between videos that mentioned anxiety and those that mentioned depression (p < 0.001). The numbers of videos focused on anxiety and depression were correlated with themes such as life stressors and social distancing (p < 0.05). Videos that did not make recommendations for dealing with stressors had more positive ratings than videos that did make such recommendations (p = 0.002). The content of YouTube videos addressing mental health issues during COVID-19 reflects the actual prevalence of specific mental health conditions during this same time period. Viewer ratings may be indicative of the public need for information about mental health conditions and validation for difficult experiences on social media sites. YouTube must be better utilized to disseminate information about mental illness.
When the COVID-19 pandemic began, many 12-step meetings rapidly transitioned from an in-person to an online format. In this qualitative focus group study, 17 attendees of 12-step programs from six U.S. states participated in one of two focus groups on Zoom platform in August 2021 in which their experiences of attending online versus in-person meetings were explored. Respondents praised the accessibility and convenience of online meetings, and the ability to interact with members from different geographic locations. However, they noted the loss of intensive social support found at in-person meetings and technological/procedural challenges that remain unsolved online.
Aptamer ligand discovery against multiple molecules expressed on whole cells is an essential component in molecular tool development. However, owing to their intrinsic structural characteristics, cell-surface receptors have proven to be challenging targets in ligand discovery. Several variants to systematic evolution of ligands by exponential enrichment (SELEX) have been introduced to address the ″target problem″ for aptamer screening. To this end, we introduced a variant of SELEX, termed ligand-guided selection (LIGS), to identify highly specific aptamers against complex cell-surface markers in their native state. So far, the application of LIGS has been aimed at identifying aptamers against the most dominant receptors on the cell surface. Here, we report that LIGS can be expanded to identify two receptors on the same cell surface, paving the way to generate a multiplexed ligand discovery platform based on SELEX-targeting membrane receptors in their native functional state. Using CD19 and CD20 expressed on Toledo cells as a model system, multiple aptamer families were evolved against Toledo cells. We then utilized two monoclonal antibodies (mAbs) against CD20 and CD19 to selectively partition specific aptamers against CD19 and CD20. Following biochemical characterization, we introduce two specific aptamers against CD19 and two specific aptamers against CD20 with high affinity. Multi-target LIGS, as reported here, demonstrates a successful combinatorial approach for nucleic acid library screening to generate multiple artificial nucleic acid ligands against multiple receptors expressed on a single cell.
Decades of research from across the globe highlight unequal and unfair division of household labor as a key factor that leads to relationship distress and demise. But does it have to? Testing a priori predictions across three samples of individuals cohabiting with a romantic partner during the COVID-19 pandemic ( N = 2,193, including 476 couples), we found an important exception to this rule. People who reported doing more of the household labor and who perceived the division as more unfair were less satisfied across the early weeks and ensuing months of the pandemic, but these negative effects disappeared when people felt appreciated by their partners. Feeling appreciated also appeared to buffer against the negative effects of doing less, suggesting that feeling appreciated may offset the relational costs of unequal division of labor, regardless of who contributes more. These findings generalized across gender, employment status, age, socioeconomic status, and relationship length.
Excited state quenching is a key step in photochemical reactions that involve energy or electron transfer. High reaction quantum yields require sufficiently high concentrations of a quencher to ensure efficient quenching. The determination of quencher concentrations is typically done through trial and error. Using kinetic modeling, however, a simple relationship was developed that predicts the concentration of quencher necessary to quench 90% of excited states, using only the photosensitizer lifetime and the rate constant for quenching as inputs. Comparison of the predicted quencher concentrations and quencher concentrations used in photoredox reactions featuring acridinium-based photocatalysts reveals that the majority of reactions used quencher concentrations significantly below the predicted concentration. This suggests that these reactions exhibit low quantum yields, requiring long reaction times and/or intense light sources.
Recently, the idea of using neutrino oscillations to measure the Hubble constant was introduced. We show that such a task is unfeasible because for typical energies of cosmic neutrinos, oscillations average out over cosmological distances and so the oscillation probability depends only on the mixing angles.
Given a graph , its auxiliary square‐graph is the graph whose vertices are the non‐edges of and whose edges are the pairs of non‐edges which induce a square (i.e., a 4‐cycle) in . We determine the threshold edge‐probability at which the Erdős–Rényi random graph begins to asymptotically almost surely (a.a.s.) have a square‐graph with a connected component whose squares together cover all the vertices of . We show , a polylogarithmic improvement on earlier bounds on due to Hagen and the authors. As a corollary, we determine the threshold at which the random right‐angled Coxeter group a.a.s. becomes strongly algebraically thick of order 1 and has quadratic divergence.
The Forward Physics Facility (FPF) is a proposal to create a cavern with the space and infrastructure to support a suite of far-forward experiments at the Large Hadron Collider during the High Luminosity era. Located along the beam collision axis and shielded from the interaction point by at least 100 m of concrete and rock, the FPF will house experiments that will detect particles outside the acceptance of the existing large LHC experiments and will observe rare and exotic processes in an extremely low-background environment. In this work, we summarize the current status of plans for the FPF, including recent progress in civil engineering in identifying promising sites for the FPF and the experiments currently envisioned to realize the FPF’s physics potential. We then review the many Standard Model and new physics topics that will be advanced by the FPF, including searches for long-lived particles, probes of dark matter and dark sectors, high-statistics studies of TeV neutrinos of all three flavors, aspects of perturbative and non-perturbative QCD, and high-energy astroparticle physics.
Regular physical exercise can decrease the risk for obesity, diabetes, and cardiovascular disease, increase life expectancy, and promote psychological health and neurocognitive functioning. Cross-sectional studies show that cardiorespiratory fitness level (VO2 max) is associated with enhanced brain health, including improved mood state and heightened cognitive performance. Interventional studies are consistent with these cross-sectional studies, but most have focused on low-fit populations. Few such studies have asked if increasing levels of physical activity in moderately fit people can significantly enhance mood, motivation, and cognition. Therefore, the current study investigated the effects of increasing aerobic exercise in moderately fit individuals on psychological state and cognitive performance. We randomly assigned moderately fit healthy adults, 25–59 years of age, who were engaged in one or two aerobic exercise sessions per week to either maintain their exercise regimen (n = 41) or increase their exercise regimen (i.e., 4–7 aerobic workouts per week; n = 39) for a duration of 3 months. Both before and after the intervention, we assessed aerobic capacity using a modified cardiorespiratory fitness test, and hippocampal functioning via various neuropsychological assessments including a spatial navigation task and the Mnemonic Similarity Task as well as self-reported measures including the Positive and Negative Affect Scale, Beck Anxiety Inventory, State-Trait Anxiety Inventory, Perceived Stress Scale, Rumination Scale, Eating Disorders Examination, Eating Attitudes Test, Body Attitudes Test, and Behavioral Regulation of Exercise Questionnaire. Consistent with our initial working hypotheses, we found that increasing exercise significantly decreased measures of negative affect, including fear, sadness, guilt, and hostility, as well as improved body image. Further, we found that the total number of workouts was significantly associated with improved spatial navigation abilities and body image as well as reduced anxiety, general negative affect, fear, sadness, hostility, rumination, and disordered eating. In addition, increases in fitness levels were significantly associated with improved episodic memory and exercise motivation as well as decreased stress and disordered eating. Our findings are some of the first to indicate that in middle-aged moderately-fit adults, continuing to increase exercise levels in an already ongoing fitness regimen is associated with additional benefits for both psychological and cognitive health.
Introduction The effects of dietary protein on body composition and physical performance seemingly depend on the essential amino acid profile of the given protein source, although controversy exists about whether animal protein sources may possess additional anabolic properties to plant-based protein sources. Purpose To compare the effects of a novel plant-based protein matrix and whey protein supplementation on body composition, strength, power, and endurance performance of trained futsal players. Methods Fifty male futsal players were followed during 8 weeks of supplementation, with 40 completing the study either with plant-based protein ( N = 20) or whey protein ( N = 20). The following measures were assessed: bone mineral content, lean body mass, and fat mass; muscle thickness of the rectus femoris; total body water; blood glucose, hematocrit, C-reactive protein, aspartate aminotransferase, alanine aminotransferase, creatine kinase, creatinine, and estimated glomerular filtration rate; salivary cortisol; maximal strength and 1-RM testing of the back squat and bench press exercises; muscle power and countermovement jump; VO 2max and maximal aerobic speed. Subjects were asked to maintain regular dietary habits and record dietary intake every 4 weeks through 3-day food records. Results No differences in any variable were observed between groups at baseline or pre- to post-intervention. Moreover, no time * group interaction was observed in any of the studied variables, and a time effect was only observed regarding fat mass reduction. Conclusions Supplementing with either a novel plant-based protein matrix or whey protein did not affect any of the variables assessed in high-level futsal players over 8 wks. These results suggest that whey protein does not possess any unique anabolic properties over and above those of plant-based proteins when equated to an essential amino acid profile in the population studied. Furthermore, when consuming a daily protein intake >1.6 g/kg ⁻¹ , additional protein supplementation does not affect body composition or performance in trained futsal players, regardless of protein type/source.
Objective: To examine the effect of plyometric jump training on skeletal muscle hypertrophy in healthy individuals. Methods: A systematic literature search was conducted in the databases PubMed, SPORTDiscus, Web of Science, and Cochrane Library up to September 2021. Results: Fifteen studies met the inclusion criteria. The main overall finding (44 effect sizes across 15 clusters median = 2, range = 1–15 effects per cluster) indicated that plyometric jump training had small to moderate effects [standardised mean difference (SMD) = 0.47 (95% CIs = 0.23–0.71); p < 0.001] on skeletal muscle hypertrophy. Subgroup analyses for training experience revealed trivial to large effects in non-athletes [SMD = 0.55 (95% CIs = 0.18–0.93); p = 0.007] and trivial to moderate effects in athletes [SMD = 0.33 (95% CIs = 0.16–0.51); p = 0.001]. Regarding muscle groups, results showed moderate effects for the knee extensors [SMD = 0.72 (95% CIs = 0.66–0.78), p < 0.001] and equivocal effects for the plantar flexors [SMD = 0.65 (95% CIs = −0.25–1.55); p = 0.143]. As to the assessment methods of skeletal muscle hypertrophy, findings indicated trivial to small effects for prediction equations [SMD = 0.29 (95% CIs = 0.16–0.42); p < 0.001] and moderate-to-large effects for ultrasound imaging [SMD = 0.74 (95% CIs = 0.59–0.89); p < 0.001]. Meta-regression analysis indicated that the weekly session frequency moderates the effect of plyometric jump training on skeletal muscle hypertrophy, with a higher weekly session frequency inducing larger hypertrophic gains [β = 0.3233 (95% CIs = 0.2041–0.4425); p < 0.001]. We found no clear evidence that age, sex, total training period, single session duration, or the number of jumps per week moderate the effect of plyometric jump training on skeletal muscle hypertrophy [β = −0.0133 to 0.0433 (95% CIs = −0.0387 to 0.1215); p = 0.101–0.751]. Conclusion: Plyometric jump training can induce skeletal muscle hypertrophy, regardless of age and sex. There is evidence for relatively larger effects in non-athletes compared with athletes. Further, the weekly session frequency seems to moderate the effect of plyometric jump training on skeletal muscle hypertrophy, whereby more frequent weekly plyometric jump training sessions elicit larger hypertrophic adaptations.
Illicit economies have become a major driver of socio-environmental change in Latin America’s rural spaces. The arrival of transnational drug trade networks in rural communities has significantly altered the economic, political, and social dynamics of entire regions. The drug trade has particularly affected the ancestral territories of Indigenous and Afro-descendent peoples, which coincide with significant areas of forests and high biodiversity, increasingly making trafficking an issue of racial and environmental justice as well. Furthermore, the decades-long drug wars, sponsored in large part by the United States Government, have fundamentally altered economic, social, environmental, and political conditions in areas of production and transshipment. The convergence of competing claims on rural spaces coupled with the violence provoked by the drug trade and state reactions to it enable and constrain possibilities for transformative action on the part of rural communities, and for development and governance projects. In this introduction to the Special Issue, we provide an overview of cross-cutting insights and key conceptual and methodological themes from the nine included papers. These findings challenge normative narratives of how illicit economies negatively affect political stability and economic development, problematizing especially the role of the state and market economies in this nexus. These papers also make clear the importance of mixed methods and ethnographic research that attends to questions of power to describe, explain, and transform illicit economies’ roles in this dynamic region.
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Ryan Raaum
  • Department of Anthropology
Sandra Levey
Edward L Jarroll
  • Department of Biological Sciences
Manfred Philipp
  • Department of Chemistry
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