Determination of the Concentration of Gases by Measurement of Pressure

For the determination of the concentration of gases by means of pressure measurement, a precise equation of state is given by which analysis can be carried out within an accuracy of 10 ppm. The parameters of the equation of state are explicitely reported for carbon dioxide, argon, and helium

Non-response in the American Time Use Survey: Who Is Missing from the Data and How Much Does It Matter?

This paper examines non-response in a large government survey. The response rate for the American Time Use Survey (ATUS) has been below 60 percent for the first two years of its existence, raising questions about whether the results can be generalized to the target population. The paper begins with an analysis of the types of non-response encountered in the ATUS. We find that non-contact accounts for roughly 60 percent of ATUS non-response, with refusals accounting for roughly 40 percent. Next, we examine two hypotheses about the causes of this non-response. We find little support for the hypothesis that busy people are less likely to respond to the ATUS, but considerable support for the hypothesis that people who are weakly integrated into their communities are less likely to respond, mostly because they are less likely to be contacted. Finally, we compare aggregate estimates of time use calculated using the ATUS base weights without any adjustment for non-response to estimates calculated using the ATUS final weights with a non-response adjustment and to estimates calculated using weights that incorporate our own non-response adjustments based on a propensity model. While there are some modest differences, the three sets of estimates are broadly similar. The paper ends with a discussion of survey design features, their effect on the types and level of non-response, and the tradeoffs associated with different design choices.

Social tourism and its ethical foundations

Although social tourism has been seen in a number of countries as having potential to counter social exclusion, formulating a definition for the term is difficult. "Social tourism" is used to describe a variety of initiatives for a variety of different social groups. These range from holidays for children from low-income backgrounds, through improving accessibility in hotels, to offering ecological holidays. This article discusses the definitions of "social tourism," distinguishing host-related and visitor-related forms, and aims to clarify its potential value in combating social exclusion. It does so by examining the ethical values underlying the way social tourism is defined and suggesting a theoretical framework for the effects of social tourism. Some ethical views of society place an a priori moral duty on the stronger strata to support the weaker. Others do not judge the support of the weaker strata as an a priori dominant ethical principle, and judge the welfare of the state by the opportunity of all its strata. Ethical positions that see stronger strata as having a moral duty to support the weaker are more likely to be supportive toward both host-related and visitor-related social tourism. Those that do not will probably support host-related social tourism, but will support visitor-related social tourism, if publicly funded, only if it can demonstrate benefits for the whole of society. In Western liberal democracies where this is a prevailing view, visitor-related social tourism might justify public expenditure as a potential tool to combat social exclusion. It can be seen as a merit good if it improves excluded peoples' handicapping characteristics, through, for example, beneficial effects in health, self-esteem, and improvement of family relationships. However, there is little research to test its effectiveness in achieving these outcomes. Further research is required to evaluate whether social tourism can have a significant role in combating social exclusion, and thus justify support from public expenditure

Tourism and social policy: the value of social tourism

Social Tourism for low-income groups forms part of social policy in several countries of mainland Europe, but little research evidence of its benefits exists. This study empirically examines these benefits in terms of increases in social and family capital. Interviews and focus groups were conducted with participating families and their support workers, in a semi-longitudinal research design. Social Tourism was found to increase family capital in the short term, and social capital—in terms of social networks, related pro-active behavior and self-esteem—in the medium term. These increases can be seen as beneficial for the participants and to wider society. Consequently it is suggested that Social Tourism may be a cost-effective addition to social policy. Keywords: Social Tourism, low-income, social capital, family capital

Segregation of an intruder in a heated granular dense gas

A recent segregation criterion [V. Garz\'o, Phys. Rev. E \textbf{78}, 020301(R) (2008)] based on the thermal diffusion factor $\Lambda$ of an intruder in a heated granular gas described by the inelastic Enskog equation is revisited. The sign of $\Lambda$ provides a criterion for the transition between the Brazil-nut effect (BNE) and the reverse Brazil-nut effect (RBNE). The present theory incorporates two extra ingredients not accounted for by the previous theoretical attempt. First, the theory is based upon the second Sonine approximation to the transport coefficients of the mass flux of intruder. Second, the dependence of the temperature ratio (intruder temperature over that of the host granular gas) on the solid volume fraction is taken into account in the first and second Sonine approximations. In order to check the accuracy of the Sonine approximation considered, the Enskog equation is also numerically solved by means of the direct simulation Monte Carlo (DSMC) method to get the kinetic diffusion coefficient $D_0$. The comparison between theory and simulation shows that the second Sonine approximation to $D_0$ yields an improvement over the first Sonine approximation when the intruder is lighter than the gas particles in the range of large inelasticity. With respect to the form of the phase diagrams for the BNE/RBNE transition, the kinetic theory results for the factor $\Lambda$ indicate that while the form of these diagrams depends sensitively on the order of the Sonine approximation considered when gravity is absent, no significant differences between both Sonine solutions appear in the opposite limit (gravity dominates the thermal gradient). In the former case (no gravity), the first Sonine approximation overestimates both the RBNE region and the influence of dissipation on thermal diffusion segregation.Comment: 9 figures; to be published in Phys. Rev.

Defining childhood severe falciparum malaria for intervention studies.

Background Clinical trials of interventions designed to prevent severe falciparum malaria in children require a clear endpoint. The internationally accepted definition of severe malaria is sensitive, and appropriate for clinical purposes. However, this definition includes individuals with severe nonmalarial disease and coincident parasitaemia, so may lack specificity in vaccine trials. Although there is no “gold standard” individual test for severe malaria, malaria-attributable fractions (MAFs) can be estimated among groups of children using a logistic model, which we use to test the suitability of various case definitions as trial endpoints. Methods and Findings A total of 4,583 blood samples were taken from well children in cross-sectional surveys and from 1,361 children admitted to a Kenyan District hospital with severe disease. Among children under 2 y old with severe disease and over 2,500 parasites per microliter of blood, the MAFs were above 85% in moderate- and low-transmission areas, but only 61% in a high-transmission area. HIV and malnutrition were not associated with reduced MAFs, but gastroenteritis with severe dehydration (defined by reduced skin turgor), lower respiratory tract infection (clinician's final diagnosis), meningitis (on cerebrospinal fluid [CSF] examination), and bacteraemia were associated with reduced MAFs. The overall MAF was 85% (95% confidence interval [CI] 83.8%–86.1%) without excluding these conditions, 89% (95% CI 88.4%–90.2%) after exclusions, and 95% (95% CI 94.0%–95.5%) when a threshold of 2,500 parasites/μl was also applied. Applying a threshold and exclusion criteria reduced sensitivity to 80% (95% CI 77%–83%). Conclusions The specificity of a case definition for severe malaria is improved by applying a parasite density threshold and by excluding children with meningitis, lower respiratory tract infection (clinician's diagnosis), bacteraemia, and gastroenteritis with severe dehydration, but not by excluding children with HIV or malnutrition