1,789 research outputs found
The Gas Temperature of Starless Cores in Perseus
In this paper we study the determinants of starless core temperatures in the
Perseus molecular cloud. We use NH3 (1,1) and (2,2) observations to derive core
temperatures (T_kin) and data from the COMPLETE Survey of Star Forming Regions
and the c2d Spitzer Legacy Survey for observations of the other core and
molecular cloud properties. The kinetic temperature distribution probed by NH3
is in the fairly narrow range of 9 - 15 K. We find that cores within the
clusters IC348 and NGC1333 are significantly warmer than "field" starless
cores, and T_kin is higher within regions of larger extinction-derived column
density. Starless cores in the field are warmer when they are closer to class
O/I protostars, but this effect is not seen for those cores in clusters. For
field starless cores, T_kin is higher in regions in which the 13CO linewidth
and the 1.1mm flux from the core are larger, and T_kin is lower when the the
peak column density within the core and average volume density of the core are
larger. There is no correlation between T_kin and 13CO linewidth, 1.1mm flux,
density or peak column density for those cores in clusters. The temperature of
the cloud material along the line of sight to the core, as measured by CO or
far-infrared emission from dust, is positively correlated with core temperature
when considering the collection of cores in the field and in clusters, but this
effect is not apparent when the two subsamples of cores are considered
separately.Comment: Accepted to ApJ; 13 pages, including 3 tables and three figure
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Transport responses to an economic blockade: necessity nudges Cuba towards a less transport intensive society
In transport terms, the Caribbean island nation of Cuba is unique because for the past forty years it has been subjected to an economic blockade by its erstwhile dominant trading partner, the United States. Furthermore, this economic pressure was exacerbated in the early 1990s with the political and economic collapse of the Former Soviet Union, and the Eastern European Socialist countries which had replaced the United States as Cuba’s principal trading partners. These events have led to a transformation in how goods and people are moved, not least because of a huge reduction in the amount of hard currency available to pay for fuel, vehicles and spare parts. This resulted in a number of innovative behavioural and technological outcomes.
In short, the impact of the post-Soviet State of Emergency on travel patterns in Cuba meant that Cuban imports as a whole fell by 75%, from 8.1bn Cuban Pesos in 1989 to 2.0bn Cuban Pesos in 1993, while over the same period in the transport sector, fuel (i.e. oil) imports were cut by 76%, and imports of transport equipment fell by 86%
Comparing Star Formation on Large Scales in the c2d Legacy Clouds: Bolocam 1.1 mm Dust Continuum Surveys of Serpens, Perseus, and Ophiuchus
We have undertaken an unprecedentedly large 1.1 millimeter continuum survey
of three nearby star forming clouds using Bolocam at the Caltech Submillimeter
Observatory. We mapped the largest areas in each cloud at millimeter or
submillimeter wavelengths to date: 7.5 sq. deg in Perseus (Paper I), 10.8 sq.
deg in Ophiuchus (Paper II), and 1.5 sq. deg in Serpens with a resolution of
31", detecting 122, 44, and 35 cores, respectively. Here we report on results
of the Serpens survey and compare the three clouds. Average measured angular
core sizes and their dependence on resolution suggest that many of the observed
sources are consistent with power-law density profiles. Tests of the effects of
cloud distance reveal that linear resolution strongly affects measured source
sizes and densities, but not the shape of the mass distribution. Core mass
distribution slopes in Perseus and Ophiuchus (alpha=2.1+/-0.1 and
alpha=2.1+/-0.3) are consistent with recent measurements of the stellar IMF,
whereas the Serpens distribution is flatter (alpha=1.6+/-0.2). We also compare
the relative mass distribution shapes to predictions from turbulent
fragmentation simulations. Dense cores constitute less than 10% of the total
cloud mass in all three clouds, consistent with other measurements of low
star-formation efficiencies. Furthermore, most cores are found at high column
densities; more than 75% of 1.1 mm cores are associated with Av>8 mag in
Perseus, 15 mag in Serpens, and 20-23 mag in Ophiuchus.Comment: 32 pages, including 18 figures, accepted for publication in Ap
Chemical determinants of occupational hypersensitivity pneumonitis
Background: Workplace inhalational exposures to low molecular weight (LMW) chemicals cause hypersensitivity pneumonitis (HP) as well as the more common manifestation of respiratory hypersensitivity, occupational asthma (OA).
Aims: To explore whether chemical causation of HP is associated with different structural and physico-chemical determinants from OA.
Methods: Chemical causes of human cases of HP and OA were identified from searches of peer-reviewed literature up to the end of 2011. Each chemical was categorised according to whether or not it had been the attributed cause of at least one case of HP. The predicted asthma hazard was determined for each chemical using a previously developed quantitative structure-activity relationship (QSAR) model. The chemicals in both sets were independently and ‘blindly’ analysed by an expert in mechanistic chemistry for a qualitative prediction of protein cross-linking potential and determination of lipophilicity (log Kow).
Results: Ten HP causing chemicals were identified and had a higher median QSAR predicted asthma hazard than the control group of 101 OA causing chemicals (p < 0.005). Nine of ten HP causing chemicals were predicted to be protein cross-linkers compared to 24/92 controls (p<0.0001). The distributions of log Kow indicated higher values for the HP list (median 3.47) compared to controls (median 0.81) (p < 0.05).
Conclusion: These findings suggest that chemicals capable of causing HP tend to have higher predicted asthma hazard, are more lipophilic and are more likely to be protein cross-linkers than those causing OA.
Key words: hypersensitivity pneumonitis, occupational chemicals, occupational respiratory disease, toxic inhalatio
Tax treatment of employer commuting support: an international review
Correctly pricing transport behaviour to take account of the ‘external’ costs such as congestion and emissions imposed on society by excessive car use has long been a tenet of effective transportation demand management. But while policy‐makers have striven to increase public transport subsidies, raise petrol taxes and introduce road‐user charging schemes to price the real costs of car travel properly, in most cases correcting the wider influences of the personal tax regime has begun only relatively recently. This paper is based on work undertaken for the Department of the Environment, Transport and the Regions, and the Inland Revenue of the UK government, which is currently working on addressing this very issue. In addition to reporting the British situation, the paper also uses a series of case studies to outline how this same process has been approached in the USA, Ireland, Germany, the Netherlands, Switzerland and Norway, and how successful they have been thus far with respect to transportation demand management objectives. It then draws conclusions about which direction policy‐makers should be aiming for in the future
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Setting targets for HIV/AIDS-What lessons can be learned from other disease control programmes?
Our analysis of experience from programmes targeting malaria, leprosy and TB shows the importance of drawing broadly on research and implementation expertise, and civil society more broadly, when setting targets for HIV control. The engagement of stakeholders from the highest burden settings, including affected populations, is crucial, to ensure that disease control efforts uphold human rights and tackle HIV-related stigma and discrimination.
An appropriate balance is needed between ambitious, galvanising global targets that drive funding and political/public engagement, and targets that reflect the complexities and local epidemiological variations in disease profile. Ethical issues and unintended consequences need to be considered when setting targets—particularly around local effects and opportunity costs of having foregone other areas of disease control and public health. Intermediate and adaptable targets are needed that allow for course corrections to programmes.
Overly burdensome reporting requirements for individual local programmes and countries should be avoided, as well as potential for overlapping and sometimes conflicting targets both within and across vertical disease programmes. Process targets should be distinguished from outcome targets, which should be measurable and based on high-quality data.
Retention of expert healthcare worker skills and specialist services is vital, while moving towards integrated health systems if effective disease control programmes are to be maintained. Target development should seek areas of programme delivery where an opportunity to codevelop targets and integrate services exists. Global efforts to move to universal health coverage (UHC), for example, could be factored in when developing targets.
Sustaining investment and continuing political interest in the end phase of any elimination or eradication strategy, once incidence and prevalence are low, are critical to achieve success. Equity- and access-based service delivery targets become increasingly important as the elimination strategy nears its end and should be factored into planning.
Achieving disease elimination and/or eradication is only possible with sufficient investment in research to develop new prevention tools such as vaccines, point-of-care diagnostics, and treatments to counteract the effects of increasing drug resistance and the challenging latency period of diseases; public health infrastructure upgrades that address wider determinants of health; and health and surveillance systems that allow for equitable delivery and access to services
Identifying a human rights–based approach to obesity for States and civil society
Summary Obesity and its comorbidities pose daunting challenges to global health and development in the 21st century. This paper reviews some commonalities between obesity and another global health challenge, the pandemic of human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS). International human rights law was an important catalyst for civil society movements that helped to overcome inertia and generate political will for State action in response to HIV and AIDS. Drawing on the HIV experience, the authors propose a conceptual model for a human rights?based response to obesity founded on the twin pillars of State obligations and civil society engagement. Framing States' obligations to address the global obesity pandemic as a matter of international law, informed by the examples of the United Nations ?International Guidelines on HIV/AIDS and Human Rights? and the General Comments of the United Nations human rights treaty bodies on HIV and AIDS, provides a normative framework to guide State actions and opportunities to engage the extensive accountability mechanisms of the United Nations international human rights system. In addition, it provides civil society organizations with the language and tools to demand State action on obesity. The authors call for similar authoritative guidance for States on the application of international human rights law to obesity
WASP-29b: A Saturn-sized transiting exoplanet
We report the discovery of a Saturn-sized planet transiting a V = 11.3, K4
dwarf star every 3.9 d. WASP-29b has a mass of 0.24+/-0.02 M_Jup and a radius
of 0.79+/-0.05 R_Jup, making it the smallest planet so far discovered by the
WASP survey, and the exoplanet most similar in mass and radius to Saturn. The
host star WASP-29 has an above-Solar metallicity and fits a possible
correlation for Saturn-mass planets such that planets with higher-metallicity
host stars have higher core masses and thus smaller radii.Comment: 6 pages, submitted to ApJ
WASP-26b : a 1-Jupiter-mass planet around an early-G-type star
We report the discovery of WASP-26b, a moderately over-sized Jupiter-mass exoplanet transiting its 11.3-mag early-G-type host star (1SWASP J001824.70-151602.3; TYC 5839-876-1) every 2.7566 days. A simultaneous fit to transit photometry and radial-velocity measurements yields a planetary mass of 1.02 ± 0.03 MJup and radius of 1.32 ± 0.08 RJup. The host star, WASP-26, has a mass of
1.12 ± 0.03 M and a radius of 1.34 ± 0.06 R and is in a visual double with a fainter K-type star. The two stars are at least a common-proper motion pair with a common distance of around 250 ± 15 pc and an age of 6 ± 2 Gy
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