Why Surplus Consumption in the Habit Model May be Less Persistent than You Think

In U.S. data, value stocks have higher expected excess returns and higher CAPM alphas than growth stocks. We find the external-habit model of Campbell and Cochrane (1999) can generate a value premium in both CAPM alpha and expected excess return so long as the persistence of the log surplus-consumption ratio is not too high. In contrast, Lettau and Wachter (2007) find that when the log surplus-consumption ratio is assumed to be highly persistent as in Campbell and Cochrane, the external-habit model generates a growth premium in expected excess return. However, the micro evidence favors a less persistent log surplus-consumption ratio. We choose a value for this persistence which is sufficiently low that the most recent 2 years of log consumption contribute over 98% of all past consumption to log habit, which is a much more reasonable number than the 25% contribution generated by the Lettau-Wachter value. In our model, expected consumption is slowly mean-reverting, as in the long-run risk model of Bansal and Yaron (2004), which is why our model is able to generate a price-dividend ratio for aggregate equity that exhibits the high autocorrelation found in the data, despite the very low persistence of the price-of-risk state variable. Our results suggest that an external habit model in the spirit of Campbell and Cochrane can deliver an empirically sensible value premium once the persistence of the surplus consumption ratio is calibrated to the micro evidence rather than set to a value close to one. When we allow the conditional volatility of consumption growth to also be slowly mean reverting as in the long-run risk model of Bansal and Yaron, our model is also able to generate empirically sensible predictability of long-horizon returns using the price-dividend ratio, without eroding the value premium. Our results also suggest that models with fast-moving habit can deliver several empirical properties of aggregate dividend strips that have been recently documented.

PEAK RATE OF TRUNK ENERGY OUTFLOW DIFFERS BETWEEN PITCH TYPES IN SOFTBALL PITCHERS

In softball players, it is unclear how certain pitch types may increase the risk of injury. The purpose of this study was to determine energy flow differences in the trunk and upper-arm segments between pitch types. Twenty-three softball pitchers participated. Absolute values of trunk energy inflow (IF) and outflow (OF), and upper arm IF, as well as segment energy flow when normalized to pitch speed were assessed in three pitch types. Differences between trunk energy OF were found between fastballs compared to curveballs and dropballs. When normalized to pitch speed, trunk energy OF only differed between fastballs and dropballs. For the upper arm, absolute differences were found between the fastball and curveball. Similar rates of humerus IF between the fastball and dropball and less trunk outflow in the dropball may indicate increased upper extremity demands in the dropball

Targeted treatment of yaws with contact tracing : how much do we miss?

Yaws is a disabling bacterial infection found primarily in warm and humid tropical areas. The World Health Organization strategy mandates an initial round of total community treatment (TCT) with single-dose azithromycin followed either by further TCT or active case-finding and treatment of cases and their contacts (the Morges strategy). We sought to investigate the effectiveness of the Morges strategy. We employed a stochastic household model to study the transmission of infection using data collected from a pre-TCT survey conducted in the Solomon Islands. We used this model to assess the proportion of asymptomatic infections that occurred in households without active cases. This analysis indicated that targeted treatment of cases and their household contacts would miss a large fraction of asymptomatic infections (65%–100%). This fraction was actually higher at lower prevalences. Even assuming that all active cases and their households were successfully treated, our analysis demonstrated that at all prevalences present in the data set, up to 90% of (active and asymptomatic) infections would not be treated under household-based contact tracing. Mapping was undertaken as part of the study “Epidemiology of Yaws in the Solomon Islands and the Impact of a Trachoma Control Programme,” in September–October 2013

Acute dehydration impairs endurance without modulating neuromuscular function

Introduction/Purpose: This study examined the influence of acute dehydration on neuromuscular function. Methods: On separate days, combat sports athletes experienced in acute dehydration practices (n = 14) completed a 3 h passive heating intervention (40∘C, 63% relative humidity) to induce dehydration (DHY) or a thermoneutral euhydration control (25∘C, 50% relative humidity: CON). In the ensuing 3 h ad libitum fluid and food intake was allowed, after which participants performed fatiguing exercise consisting of repeated unilateral knee extensions at 85% of their maximal voluntary isometric contraction (MVIC) torque until task failure. Both before and after the fatiguing protocol participants performed six MVICs during which measures of central and peripheral neuromuscular function were made. Urine and whole blood samples to assess urine specific gravity, urine osmolality, haematocrit and serum osmolality were collected before, immediately and 3 h after intervention. Results: Body mass was reduced by 3.2 ± 1.1% immediately after DHY (P \u3c 0.001) but recovered by 3 h. Urine and whole blood markers indicated dehydration immediately after DHY, although blood markers were not different to CON at 3 h. Participants completed 28% fewer knee extensions at 85% MVIC (P \u3c 0.001, g = 0.775) and reported a greater perception of fatigue (P = 0.012) 3 h after DHY than CON despite peak torque results being unaffected. No between-condition differences were observed in central or peripheral indicators of neuromuscular function at any timepoint. Conclusion: Results indicate that acute dehydration of 3.2% body mass followed by 3 h of recovery impairs muscular strength-endurance and increases fatigue perception without changes in markers of central or peripheral function. These findings suggest that altered fatigue perception underpins muscular performance decrements in recovery from acute dehydration

EFFICIENCY INDEX USED TO ASSESS SHOULDER STRESS IN COLLEGE SOFTBALL PITCHERS THROUGHOUT A SIMULATED GAME

Shoulder distraction forces in softball pitching are known to have a positive impact on performance yet a negative impact on musculoskeletal health. The purpose of this study was to assess changes in shoulder stress across innings pitched using Efficiency Arm-Stress Index (EASI) scores. Motion capture was used on collegiate softball pitchers pitching a simulated game. Peak shoulder distraction force was obtained using inverse dynamics procedures and used to calculate an EASI score (fastball velocity divided by peak shoulder distraction force in percent body weight). A RM·ANOVA revealed inning had no effect on EASI score (F[6,7]=1.28, p=0.286). Understanding a pitcher’s efficiency score may help shape individual pitching loads. Future work should investigate clinically meaningful changes in efficiency scores and mechanisms behind low efficiencies

Seahorse Brood Pouch Transcriptome Reveals Common Genes Associated with Vertebrate Pregnancy

Viviparity (live birth) has evolved more than 150 times in vertebrates, and represents an excellent model system for studying the evolution of complex traits. There are at least 23 independent origins of viviparity in fishes, with syngnathid fishes (seahorses and pipefish) unique in exhibiting male pregnancy. Male seahorses and pipefish have evolved specialized brooding pouches that provide protection, gas exchange, osmoregulation, and limited nutrient provisioning to developing embryos. Pouch structures differ widely across the Syngnathidae, offering an ideal opportunity to study the evolution of reproductive complexity. However, the physiological and genetic changes facilitating male pregnancy are largely unknown. We used transcriptome profiling to examine pouch gene expression at successive gestational stages in a syngnathid with the most complex brood pouch morphology, the seahorse Hippocampus abdominalis. Using a unique time-calibrated RNA-seq data set including brood pouch at key stages of embryonic development, we identified transcriptional changes associated with brood pouch remodeling, nutrient and waste transport, gas exchange, osmoregulation, and immunological protection of developing embryos at conception, development and parturition. Key seahorse transcripts share homology with genes of reproductive function in pregnant mammals, reptiles, and other live-bearing fish, suggesting a common toolkit of genes regulating pregnancy in divergent evolutionary lineage

Analysis of the prevalence of HTLV-1 proviral DNA in cervical smears and carcinomas from HIV positive and negative Kenyan women

The oncogenic retrovirus human T-cell lymphotropic virus type 1 (HTLV-1) is endemic in some countries although its prevalence and relationship with other sexually transmitted infections in Sub-Saharan Africa is largely unknown. A novel endpoint PCR method was used to analyse the prevalence of HTLV-1 proviral DNA in genomic DNA extracted from liquid based cytology (LBC) cervical smears and invasive cervical carcinomas (ICCs) obtained from human immunodeficiency virus-positive (HIV+ve) and HIV-negative (HIV−ve) Kenyan women. Patient sociodemographic details were recorded by structured questionnaire and these data analysed with respect to HIV status, human papillomavirus (HPV) type (Papilocheck®) and cytology. This showed 22/113 (19.5%) of LBC’s from HIV+ve patients were positive for HTLV-1 compared to 4/111 (3.6%) of those from HIV−ve women (p = 0.0002; odds ratio (OR) = 6.42 (2.07–26.56)). Only 1/37 (2.7%) of HIV+ve and none of the 44 HIV−ve ICC samples were positive for HTLV-1. There was also a significant correlation between HTLV-1 infection, numbers of sexual partners (p < 0.05) and smoking (p < 0.01). Using this unique method, these data suggest an unexpectedly high prevalence of HTLV-1 DNA in HIV+ve women in this geographical location. However, the low level of HTLV-1 detected in HIV+ve ICC samples was unexpected and the reasons for this are unclear

Targeted Treatment of Yaws With Household Contact Tracing: How Much Do We Miss?

Yaws is a disabling bacterial infection found primarily in warm and humid tropical areas. The World Health Organization strategy mandates an initial round of total community treatment (TCT) with single-dose azithromycin followed either by further TCT or active case-finding and treatment of cases and their contacts (the Morges strategy). We sought to investigate the effectiveness of the Morges strategy. We employed a stochastic household model to study the transmission of infection using data collected from a pre-TCT survey conducted in the Solomon Islands. We used this model to assess the proportion of asymptomatic infections that occurred in households without active cases. This analysis indicated that targeted treatment of cases and their household contacts would miss a large fraction of asymptomatic infections (65%-100%). This fraction was actually higher at lower prevalences. Even assuming that all active cases and their households were successfully treated, our analysis demonstrated that at all prevalences present in the data set, up to 90% of (active and asymptomatic) infections would not be treated under household-based contact tracing. Mapping was undertaken as part of the study "Epidemiology of Yaws in the Solomon Islands and the Impact of a Trachoma Control Programme," in September-October 2013

Modeling Treatment Strategies to Inform Yaws Eradication.

Yaws is a neglected tropical disease targeted for eradication by 2030. To achieve eradication, finding and treating asymptomatic infections as well as clinical cases is crucial. The proposed plan, the Morges strategy, involves rounds of total community treatment (i.e., treating the whole population) and total targeted treatment (TTT) (i.e., treating clinical cases and contacts). However, modeling and empirical work suggests asymptomatic infections often are not found in the same households as clinical cases, reducing the utility of household-based contact tracing for a TTT strategy. We use a model fitted to data from the Solomon Islands to predict the likelihood of elimination of transmission under different intervention schemes and levels of systematic nontreatment resulting from the intervention. Our results indicate that implementing additional treatment rounds through total community treatment is more effective than conducting additional rounds of treatment of at-risk persons through TTT