A journey home: what drives how long people are homeless?

Abstract: This paper uses survival analysis to model exits over time from two alternative notions of homelessness. We are unique in being able to account for time-invariant, unobserved heterogeneity. We find that duration dependence has an inverted U-shape with exit rates initially increasing (indicating positive duration dependence) and then falling. Like previous researchers, we find results consistent with negative duration dependence in models which ignore unobserved heterogeneity. Exit rates out of homelessness fall with age and with the education level of mothers. Women are more likely than men to exit homelessness when it is broadly conceived, but appear to be less likely to exit when it is narrowly defined. Finally, higher paternal education and exemptions from welfare-related activity requirements due to either mental or physical health conditions are all associated with higher exit rates

Parenting style as an investment in human development

We propose a household production function approach to human development in which the role of parenting style in child rearing is explicitly considered. Specifically, we model parenting style as an investment in human development that depends not only on inputs of time and market goods, but also on attention, i.e. cognitive effort. Socioeconomic disadvantage is linked to parenting style and human development through the constraints that it places on cognitive capacity. Our model finds empirical support. We demonstrate that parenting style is a construct that is distinct from standard goods- and time-intensive parental investments and that effective parenting styles are negatively correlated with socioeconomic disadvantage. Moreover, parenting style is an important determinant of young adult’s human capital net of other parental investments

Virtual Borders: Online Nominal Rigidities and International Market Segmentation

Do prices respond to macro shocks? Does the mere presence of international frontiers hinder trade? We revisit these questions by studying a dataset of online book prices for a number of US and Canadian retailers. We believe our dataset is well suited to this task for a number of reasons: (1) data for multiple retailers are available; (2) the products sold are identical across retailers; (3) the sample spans a period of large fluctuations in the bilateral exchange rate; (4) the nature of the industry is such that physical distance is irrelevant beyond shipping costs which are observable; (5) nominal frictions in the form of menu costs are arguably minimal; and (6) proxies for sales are available for most retailers. Given the unique nature of our dataset, the first objective of the paper is to document the degree of price rigidity and price dispersion. Our main findings are: online book prices display significant stickiness; there is a large degree of heterogeneity across retailers in terms of price rigidity and pricing strategy; price dispersion is high both within and across borders. Also, price levels do not appear to respond to exchange rate fluctuations. Building on the predictions from a simple two-country, multi-firm model and by exploiting information contained both in prices and quantities, we show that market segmentation is probably behind this disconnect .

Heart Rate Variability Threshold Evaluation During Arm and Leg Cycling

Background: The Heart Rate Variability Threshold (HRVT) is a point of deflection in heart rate variability assessed during incremental exercise to exhaustion. This threshold is thought to represent a shift in the autonomic balance. Purpose: The purpose of this study was to evaluate (HRVT) during arm (AC) and leg cycling (LC). Methods: There were twenty-three participants (age: 23.3±4.7 years; height: 168.6±7.5 cm; weight 66.8±8.9 kg). Participants completed two graded exercise tests, one for AC and one for LC on different days. They wore a heart rate monitor which recorded R-R intervals. The test performed was a graded exercise test to exhaustion (GXT) using a ramp protocol. The root mean square of successive differences between normal heartbeats (RMSSD) of the R-R intervals during the GXT was calculated using specialized software. A time-varying moving average (64 second window and 3 second shift) was used. A piecewise fitting function consisting of two linear functions was used to detect time and RMSSD at HRVT. The time (as percentage of the total time to exhaustion) at which HRVT occurred was also calculated. Log transformation was performed in case the normality assumption was violated. A paired t-test was run for the outcomes of interest. Mean and standard deviations were reported and an alpha value of p Results: Log transformation was performed on the RMSSD and percentage at HRVT. There was no significant difference in time at HRVT (p=0.36) between AC (4.2 ± .1.0 minutes) and LC (3.9 ± 1.6 minutes) or percentage at threshold (p=0.85) between AC (49.3 ± 11.9%) and LC (50.4 ± 20.1%). There was also no significant difference in RMSSD at HRVT (p=0.93) between arm (1.3 ± 0.36 ms) and leg cycling (1.3 ± 0.54 ms). Conclusion: Time, RMSSD, and percentage at HRVT were not different between exercise modes. Autonomic balance, as measured by heart rate variability threshold, does not seem to be influenced by exercise modality

Comparative Analysis of Heart Rate Variability Between Traditional Sets and Rest Redistribution

Resistance exercise methods have different effects on the cardiovascular system. During skeletal muscular contraction, heart rate increases while heart rate variability (HRV) decreases. HRV is thought to represent the complex interaction between the sympathetic and parasympathetic branches of the autonomic nervous system. PURPOSE: This study analyzed heart rate variability during two methods of resistance exercise, traditional sets (TS) and rest redistribution sets (RR), both containing the same volume and total rest time. METHODS: Twenty-five participants (Mean ± SD: Age= 22.4 ± 3.7 y.; height = 167.5 ± 9.7 cm; body mass = 72.7 ± 14.7 kg) completed 40 repetitions of the barbell squat with 65% 1RM load. Participants completed TS (4 sets of 10 repetitions, 3-minute rest) and RR (10 sets of 4 repetitions, 1-minute rest), in a randomized order on separate days. HRV was collected from each participant using a heart rate monitor. The HRV was analyzed using a specialized software. Average windows were developed to calculate the root mean square of successive differences (RMSSD) between normal heartbeats and stress index (SI) at rest, during the exercise session, and during recovery. Log transformation was performed in the case of a violation of the normality assumption. Paired t-tests were used to compare RMSSD and SI responses at initial rest, during exercise and recovery between TS and RR. RESULTS: During the initial rest period, there were no statistical differences between RR and TS in RMSSD (p=0.36; 7.85 ± 44.2 vs. 9.14 ± 6.63, respectively or SI (p=0.81; 3.50 ± 0.43 vs. 3.41 ±0.60, respectively). However, there were statistical significance for both RMSSD (pCONCLUSION: While the vagal response does not seem to be affected by training method during recovery, stress responses were higher during RR than TS exercise, as measured by HRV. Future studies can examine HRV behavior during exercise and establish its relationship to other physiological and perceptual markers

Contextualizing the Acute Responses to Arm Cycling

The prescription of aerobic exercise modalities engaging the arm musculature have the potential to extend the reach of physical activity and promote cardiorespiratory fitness in individuals with lower body impairment due to excessive body mass, and among individuals seeking to complement and diversify standard leg training. This study compared the acute cardiopulmonary responses obtained during arm cycling and leg cycling performed at different intensities among lean and average (LA) and overfat and obese individuals (OFO). Participants were 37 young and relatively healthy adults. They were tested for mode-specific peak power output and work rate at ventilatory threshold during two randomized maximal incremental protocol tests. The experiments were four randomized constant work rate isocaloric protocols for arm cycling and leg cycling performed at heavy and moderate exercise intensities based on participants\u27 ventilatory threshold and peak power output obtained from the maximal incremental protocol tests. All experiments were matched for the same caloric expenditure of 100 kcal. Cardiopulmonary parameters and the time to expend 100 kcal (Tkcal100) were recorded. Tkcal100 was increased for the OFO in comparison to the LA group. Among the cardiopulmonary parameters measured in this study, only oxygen uptake relative to body mass was significantly different between groups; however, differences were no longer evident when oxygen uptake values were considered relative to fat-free mass. Furthermore, cardiopulmonary variables are more affected by exercise intensity than exercise mode, while responses to different intensities are not necessarily proportional. Young adults with excess body fat appear to respond less favorably to acute exercise when compared to lean and average body composition individuals, as evidenced by a longer Tkcal100

Examining Stroke Volume Changes During Exercise in Healthy Young Adults

Cardiac output is determined by the combination of heart rate and stroke volume. While heart rate is primarily influenced by cardiac autonomic input, stroke volume\u27s behavior is more intricate due to the interplay between myocardial response to stretch (Frank-Starling law) and adrenergic changes in contractility. No consensus exist on its behavior during exercise despite extensive data. PURPOSE: The aim of this study was to assess how normalized stroke volume scores (SV) change in young, healthy adult males during a graded exercise test to exhaustion (GXT). METHODS: Participants (n=20; age=22.9±2.4; BMI=23.7±2.4) were instructed to abstain from engaging in vigorous exercise for a period of 24 hours before the study, ensure they were adequately hydrated, and maintain a fasting state. Participants completed a graded exercise test to exhaustion in the morning on an electromagnetically braked cycle ergometer. SV was recorded using trans-thoracic bioimpedance device and results were averaged and normalized into five epochs. To determine the effect of GXT epochs on SV score, SV was normalized to percentage of within- subject maximum SV, and mean SV was quantified across 10 equally spaced epochs (10% of trial duration each). A mixed model was used to compare epochs. Assumptions of residual normality and homoscedasticity were visually verified using q-q plots and model predicted scores vs. residuals plots, respectively. SV score was modeled using participant as a random effect, and GXT epochs as fixed effects. Follow-up pairwise comparisons utilized Holm sequential corrections. Alpha was set at 0.05. RESULTS: There were no significant differences (p\u3e.05) between epochs 1 (85.2%±5.7) and 2 (86.6%±5.4), epochs 2 and 3 (88.8%±4.1), or among epochs 3 through 10 (91.4%±3.5). There were significant differences (p\u3c0.01) between epochs 1 and 3-10. There were significant differences between epochs 2 and 4-10. CONCLUSION: SV exhibited a general increase throught the first 30% of test duration. However, beyond this point, there was no statistically significant increase in stroke volume, indicating a relatively stable pattern after the first 30% of the test. These results in agreement with previous data that have reported a plateau in stroke volume during progressive exercise to exhaustion

Augmented collisional ionization via excited states in XUV cluster interactions

The impact of atomic excited states is investigated via a detailed model of laser-cluster interactions, which is applied to rare gas clusters in intense femtosecond pulses in the extreme ultraviolet (XUV). This demonstrates the potential for a two-step ionization process in laser-cluster interactions, with the resulting intermediate excited states allowing for the creation of high charge states and the rapid dissemination of laser pulse energy. The consequences of this excitation mechanism are demonstrated through simulations of recent experiments in argon clusters interacting with XUV radiation, in which this two-step process is shown to play a primary role; this is consistent with our hypothesis that XUV-cluster interactions provide a unique window into the role of excited atomic states due to the relative lack of photoionization and laser field-driven phenomena. Our analysis suggests that atomic excited states may play an important role in interactions of intense radiation with materials in a variety of wavelength regimes, including potential implications for proposed studies of single molecule imaging with intense X-rays.Comment: 4 pages, 2 figure

Draft genome sequence of a multidrug-resistant CTX-M-15 β-lactamase-producing uropathogenic Escherichia coli isolate (ST131-O25b-H30) from Pakistan exhibiting high potential virulence

Objectives: Uropathogenic Escherichia coli (UPEC) is the leading cause of urinary tract infections (UTI). The pandemic ST131 clonal type is associated with multidrug resistance and virulence. We report the first draft genome of an ST131-O25b-H30 strain from Pakistan, isolated from a patient with community-acquired UTI. Methods: Next-generation sequencing was performed using MiSeq and HiSeq 2500 platforms. De novo assembly of the reads was performed using SPAdes (v 3.11.). The genomic features were determined with PATRIC and RAST tool kit. Results: The 5,327,975 bp draft genome sequence has 5433 CDS and 82 tRNAs, an array of resistance genes (blaCTXM-15, blaOXA-1, blaCMY-2, sul2, catB, dfrA17, mph(A)), one class 1 integron, 77 IS elements, one transposon (Tn3-like), multiple virulence markers and seven intact prophage loci. Conclusion: In conclusion, the genome sequence of this new UPEC isolate from Pakistan provides novel insight into the genetic attributes of an epidemic clone associated with high level of resistance and virulence

Astrophysical science metrics for next-generation gravitational-wave detectors

The second generation of gravitational-wave detectors are being built and tuned all over the world. The detection of signals from binary black holes is beginning to fulfill the promise of gravitational-wave astronomy. In this work, we examine several possible configurations for third-generation laser interferometers in existing km-scale facilities. We propose a set of astrophysically motivated metrics to evaluate detector performance. We measure the impact of detector design choices against these metrics, providing a quantitative cost-benefit analyses of the resulting scientific payoffs