Sociodemographic Correlates of Sexlessness Among American Adults and Associations with Self-Reported Happiness Levels: Evidence from the U.S. General Social Survey

Although sexual activity is commonly believed to be a key component of emotional well-being, little is known about the factors associated with the absence of sexual activity or its associations with self-reported happiness. Using the U.S. General Social Survey–National Death Index 2008 dataset, a series of nationally representative surveys (1988–2002), this study analyzed the sociodemographic and lifestyle factors associated with past-year sexlessness and self-reported happiness among American adults (n = 17,744). After adjustment for marital status, there were no significant time trends evident in the proportion of American adults reporting past-year sexlessness. Among participants (age = 18–89 years), 15.2% of males and 26.7% of females reported past-year sexlessness while 8.7% of males and 17.5% of females reported no sex for 5 years or more. For both genders, past-year sexlessness was most strongly associated with older age and being currently non-married in the multivariable models. Among males, the multivariable analysis also showed that sexlessness was associated with providing less than 20% of the house-hold income (OR 2.27). In female participants, sexlessness was associated with very low income, poor health, lower financial satisfaction, absence of children, and having conservative sexual attitudes (OR 1.46–3.60). For both genders, Black race was associated with a much lower likelihood of sexlessness among currently non-married adults. The purported detrimental impact of sexlessness on self-reported happiness levels was not evident in this large, nationally representative study after adjusting for sociodemographic factors. Sexless Americans reported very similar happiness levels as their sexually active counterparts

Airline revenue management based on dynamic programming incorporating passenger sell-up behavior

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2008.Includes bibliographical references (p. 141-147).Low-fare carriers with simplified and unrestricted fare structures have rapidly grown and captured an important share of demand in the markets they enter, forcing legacy carriers to inevitably simplify their fare structures to avoid distraction of their competitiveness. Consequently, traditional Revenue Management (RM) systems, which assume independent demand of fare classes, have become less effective for legacy carriers in dealing with passengers who tend to purchase the lowest fare available in the absence of distinctions among fare products. This thesis studies two RM optimization algorithms based on dynamic programming, Lautenbacher DP (DPL) and Gallego-Van Ryzin DP (DP-GVR), that aim to control fare class closure using maximum expected revenue. The underlying principle of both DP methods considers the actual arrival pattern of passengers as a Markov decision process. DPL assumes independence of fare classes as do traditional RM methods, and determines which classes should be open for a given time frame. DP-GVR considers the fact that passengers may sell-up or buy down between fare classes, and determines which fare class should be the lowest class open for a given time frame. The goal of this thesis is to evaluate the effectiveness of DPL and DP-GVR when they account for sell-up, using not only arbitrary sell-up assumptions but also estimated sell-up rates. Based on results obtained with the Passenger Origin-Destination Simulator (PODS), we compare the performance of both methods to traditional methods under various competitive settings. Simulation results in a single origin-destination market demonstrate the potential of DPL over traditional methods when high passenger sell-up rates are assumed or estimated.(cont.) The use of DPL achieves as much as 7.3% revenue improvement over EMSRb with Q-Forecasting at high demand. In contrast, the performance of DP-GVR is weaker especially against an advanced RM method, regardless of sell-up input or estimator used. On the other hand, results from a bigger network illustrate that an airline that practices DP-GVR performs much better against both simple and advanced competing RM methods. We conclude that the performance of the theoretically appealing DPL and DP-GVR depends on the environment in which they are used, the types of passenger sell-up estimator employed, as well as the Revenue Management method applied by the competitor.by Chiu Fai Wilson Tam.S.M

Effects of coarse particulate matter on emergency hospital admissions for respiratory diseases: A time-series analysis in Hong Kong

Background: Many epidemiological studies have linked daily counts of hospital admissions to particulate matter (PM) with an aerodynamic diameter ≤ 10 μm (PM 10) and ≤ 2.5 μm (PM 2.5), but relatively few have investigated the relationship of hospital admissions with coarse PM (PM c; 2.5-10 μm aerodynamic diameter). Objectives: We conducted this study to estimate the health effects of PM c on emergency hospital admissions for respiratory diseases in Hong Kong after controlling for PM 2.5 and gaseous pollutants. Methods: We conducted a time-series analysis of associations between daily emergency hospital admissions for respiratory diseases in Hong Kong from January 2000 to December 2005 and daily PM 2.5 and PM c concentrations. We estimated PMc concentrations by subtracting PM 2.5 from PM 10 measurements. We used generalized additive models to examine the relationship between PM c (single- and multiday lagged exposures) and hospital admissions adjusted for time trends, weather conditions, influenza outbreaks, PM 2.5, and gaseous pollutants (nitrogen dioxide, sulfur dioxide, and ozone). Results: A 10.9-μg/m 3 (interquartile range) increase in the 4-day moving average concentration of PM c was associated with a 1.94% (95% confidence interval: 1.24%, 2.64%) increase in emergency hospital admissions for respiratory diseases that was attenuated but still significant after controlling for PM 2.5. Adjusting for gaseous pollutants and altering models assumptions had little influence on PM c effect estimates. Conclusion: PM c was associated with emergency hospital admissions for respiratory diseases in Hong Kong independent of PM 2.5 and gaseous pollutants. Further research is needed to evaluate health effects of different components of PM c.published_or_final_versio

Efficacy of Internet-based self-monitoring interventions on maternal and neonatal outcomes in perinatal diabetic women: A systematic review and meta-analysis

10.2196/jmir.6153Journal of Medical Internet Research188e19

Post-outburst X-ray flux and timing evolution of Swift J1822.3-1606

Swift J1822.3-1606 was discovered on 2011 July 14 by the Swift Burst Alert Telescope following the detection of several bursts. The source was found to have a period of 8.4377 s and was identified as a magnetar. Here we present a phase-connected timing analysis and the evolution of the flux and spectral properties using RXTE, Swift, and Chandra observations. We measure a spin frequency of 0.1185154343(8) s$^{-1}$ and a frequency derivative of $-4.3\pm0.3\times10^{-15}$ at MJD 55761.0, in a timing analysis that include significant non-zero second and third frequency derivatives that we attribute to timing noise. This corresponds to an estimated spin-down inferred dipole magnetic field of $B\sim5\times10^{13}$ G, consistent with previous estimates though still possibly affected by unmodelled noise. We find that the post-outburst 1--10 keV flux evolution can be characterized by a double-exponential decay with decay timescales of $15.5\pm0.5$ and $177\pm14$ days. We also fit the light curve with a crustal cooling model which suggests that the cooling results from heat injection into the outer crust. We find that the hardness-flux correlation observed in magnetar outbursts also characterizes the outburst of Swift J1822.3-1606. We compare the properties of Swift J1822.3-1606 with those of other magnetars and their outbursts.Comment: 12 pages, 8 figures, accepted for publication in Ap

Characterization of water and wildlife strains as a subgroup of Campylobacter jejuni using DNA microarrays.

Campylobacter jejuni is the leading cause of human bacterial gastroenteritis worldwide, but source attribution of the organism is difficult. Previously, DNA microarrays were used to investigate isolate source, which suggested a non-livestock source of infection. In this study we analysed the genome content of 162 clinical, livestock and water and wildlife (WW) associated isolates combined with the previous study. Isolates were grouped by genotypes into nine clusters (C1 to C9). Multilocus sequence typing (MLST) data demonstrated that livestock associated clonal complexes dominated clusters C1-C6. The majority of WW isolates were present in the C9 cluster. Analysis of previously reported genomic variable regions demonstrated that these regions were linked to specific clusters. Two novel variable regions were identified. A six gene multiplex PCR (mPCR) assay, designed to effectively differentiated strains into clusters, was validated with 30 isolates. A further five WW isolates were tested by mPCR and were assigned to the C7-C9 group of clusters. The predictive mPCR test could be used to indicate if a clinical case has come from domesticated or WW sources. Our findings provide further evidence that WW C. jejuni subtypes show niche adaptation and may be important in causing human infection

Thermal receptivity of free convective flow from a heated vertical surface: linear waves

Numerical techniques are used to study the receptivity to small-amplitude thermal disturbances of the boundary layer flow of air which is induced by a heated vertical flat plate. The fully elliptic nonlinear, time-dependent Navier–Stokes and energy equations are first solved to determine the steady state boundary-layer flow, while a linearised version of the same code is used to determine the stability characteristics. In particular we investigate (i) the ultimate fate of a localised thermal disturbance placed in the region near the leading edge and (ii) the effect of small-scale surface temperature oscillations as means of understanding the stability characteristics of the boundary layer. We show that there is a favoured frequency of excitation for the time-periodic disturbance which maximises the local response in terms of the local rate of heat transfer. However the magnitude of the favoured frequency depends on precisely how far from the leading edge the local response is measured. We also find that the instability is advective in nature and that the response of the boundary layer consists of a starting transient which eventually leaves the computational domain, leaving behind the large-time time-periodic asymptotic state. Our detailed numerical results are compared with those obtained using parallel flow theory

Elucidating the aetiology of human Campylobacter coli infections

Peer reviewedPublisher PD