12,411 research outputs found

    Micro-encapsulated phase change material (MPCM) slurries: characterization and building applications

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    © 2017 Micro-encapsulated Phase Change Material (MPCM) slurries, acting as the heat transfer fluids or thermal storage mediums, have gained applications in various building thermal energy systems, significantly enhancing their energy efficiency and operational performance. This paper presents a review of research on MPCM slurries and their building applications. The research collects information on the currently available MPCM particles and shells, studies of the physical, structural and thermal stability, and rheological properties of MPCM slurries, and identification/determination of the critical parameters and dimensionless numbers relating to the MPCM slurries’ heat transfer. The research suggests possible approaches for enhancing the heat transfer between a MPCM slurry and its surroundings, while several controversial phenomena and potential causes were also investigated. Furthermore, the research presents mathematical correlations established between different thermal and physical parameters relating to the MPCM slurries, and introduces a number of practical applications of the MPCM slurries in building thermal energy systems. Based on such extensive review and analyses, the research will help in identifying the current status, potential problems in existence, and future directions in research, development and practical application of MPCM slurries. It will also promote the development and application of cost-effective and energy-efficient PCM materials and thus contribute to achieving the UK and international targets in energy saving and carbon emission reductions in the building sector and beyond

    Another Look at the Effect of State Mandates for Health Insurance Benefits

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    The research question we address is whether state laws that require health insurance policies to provide coverage for specified benefits have affected the size of the population without any private sector health insurance coverage. The laws are often alleged to increase the cost of insurance premiums and thus reduce incentives for smaller employers to offer and for individuals to purchase health insurance. Using data from the United States Census Current Population Survey (CPS) from 1996 to 2002, we measure the effects of 2 sets of high cost benefit mandates on the probability for workers to have health insurance through their employer. We use both individual and state level analyses. Generally we find weak and statistically insignificant effects associated with benefit mandates, though we see evidence that this relationship grows stronger over time

    Luminosity Dependence in the Fundamental Plane Projections of Elliptical Galaxies

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    We analyze the fundamental plane projections of elliptical galaxies as a function of luminosity, using a sample of approximately 80,000 galaxies drawn from Data Release 4 (DR4) of the Sloan Digital Sky Survey (SDSS). We separate brightest cluster galaxies (BCGs) from our main sample and reanalyze their photometry due to a problem with the default pipeline sky subtraction for BCGs. The observables we consider are effective radius (R_e), velocity dispersion (sigma), dynamical mass (M_dyn ~ R_e sigma2), effective density (sigma2/R_e2), and effective surface brightness (mu_e). With the exception of the L-M_dyn correlation, we find evidence of variations in the slope (i.e. the power-law index) of the fundamental plane projections with luminosity for our normal elliptical galaxy population. In particular, the radius-luminosity and Faber-Jackson relations are steeper at high luminosity relative to low luminosity, and the more luminous ellipticals become progressively less dense and have lower surface brightnesses than lower luminosity ellipticals. These variations can be understood as arising from differing formation histories, with more luminous galaxies having less dissipation. Data from the literature and our reanalysis of BCGs show that BCGs have radius-luminosity and Faber-Jackson relations steeper than the brightest non-BCG ellipticals in our sample, consistent with significant growth of BCGs via dissipationless mergers. The variations in slope we find in the Faber-Jackson relation of non-BCGs are qualitatively similar to that reported in the black hole mass-velocity dispersion (M_BH-sigma) correlation. This similarity is consistent with a roughly constant value of M_BH/M_star over a wide range of early type galaxies, where M_star is the stellar mass.Comment: v2: expanded analysis of BCGs; 17 pages, 9 figures; accepted in MNRA

    Corporal punishment and youth externalizing behavior in Santiago, Chile

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    OBJECTIVES: Corporal punishment is still widely practiced around the globe, despite the large body of child development research that substantiates its short- and long-term consequences. Within this context, this paper examined the relationship between parental use of corporal punishment and youth externalizing behavior with a Chilean sample to add to the growing empirical evidence concerning the potential relationship between increased corporal punishment and undesirable youth outcomes across cultures. METHODS: Analysis was based on 919 adolescents in Santiago, Chile. Descriptive and multivariate analyses were conducted to examine the extent to which parents' use of corporal punishment and positive family measures were associated with youth externalizing behavior. Furthermore, the associations between self-reported externalizing behavior and infrequent, as well as frequent, use of corporal punishment were investigated to understand how varying levels of parental use of corporal punishment were differently related to youth outcomes. RESULTS: Both mothers' and fathers' use of corporal punishment were associated with greater youth externalizing behavior. Additionally, increases in positive parenting practices, such as parental warmth and family involvement, were met with decreases in youth externalizing behavior when controlling for youth demographics, family socioeconomic status, and parents' use of corporal punishment. Finally, both infrequent and frequent use of corporal punishment were positively associated with higher youth problem behaviors, though frequent corporal punishment had a stronger relationship with externalizing behavior than did infrequent corporal punishment. CONCLUSIONS: Parental use of corporal punishment, even on an occasional basis, is associated with greater externalizing behavior for youth while a warm and involving family environment may protect youth from serious problem behaviors. Therefore, findings of this study add to the growing evidence concerning the negative consequences of corporal punishment for youth outcomes.R01 HD033487 - NICHD NIH HHS; R01 DA021181 - NIDA NIH HH

    Relationship between discordance in parental monitoring and behavioral problems among Chilean adolescents

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    This study investigated the role of discrepancies between parent and youth reports of perceived parental monitoring in adolescent problem behaviors with a Chilean sample (N= 850). Higher levels of discordance concerning parental monitoring predicted greater levels of maladaptive youth behaviors. A positive association between parent-youth discordance and externalizing problems indicated that large adult-youth disagreement in parental monitoring may impose a great risk, despite protective efforts of parental monitoring. Although the direct relationship between parental monitoring and youth internalizing behaviors was not significant, parent-youth incongruence in monitoring was associated with greater levels of internalizing behaviors. Therefore, differing assessments of parental behaviors, as an indicator of less optimal family functioning, may provide important information about youth maladjustment and may potentially provide a beginning point for family-focused intervention.R01 DA021181 - NIDA NIH HHS; R01 DA021181-05 - NIDA NIH HHS; R01 HD033487 - NICHD NIH HH
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