Study of volatile contaminants in reclaimed water

Different methods were evaluated for reducing the volatile contaminants found in water recovered from urine by distillation. The use of activated carbon, addition of potassium permanganate, and the use of oxidation catalyst are described along with laboratory tests. It is concluded that catalytic decomposition appears to be feasible, and further investigation is recommended

Radiation-Hydrodynamic Simulations of Collapse and Fragmentation in Massive Protostellar Cores

We simulate the early stages of the evolution of turbulent, virialized, high-mass protostellar cores, with primary attention to how cores fragment, and whether they form a small or large number of protostars. Our simulations use the Orion adaptive mesh refinement code to follow the collapse from ~0.1 pc scales to ~10 AU scales, for durations that cover the main fragmentation phase, using three-dimensional gravito-radiation hydrodynamics. We find that for a wide range of initial conditions radiation feedback from accreting protostars inhibits the formation of fragments, so that the vast majority of the collapsed mass accretes onto one or a few objects. Most of the fragmentation that does occur takes place in massive, self-shielding disks. These are driven to gravitational instability by rapid accretion, producing rapid mass and angular momentum transport that allows most of the gas to accrete onto the central star rather than forming fragments. In contrast, a control run using the same initial conditions but an isothermal equation of state produces much more fragmentation, both in and out of the disk. We conclude that massive cores with observed properties are not likely to fragment into many stars, so that, at least at high masses, the core mass function probably determines the stellar initial mass function. Our results also demonstrate that simulations of massive star forming regions that do not include radiative transfer, and instead rely on a barotropic equation of state or optically thin heating and cooling curves, are likely to produce misleading results.Comment: 23 pages, 18 figures, emulateapj format. Accepted to ApJ. This version has minor typo fixes and small additions, no significant changes. Resolution of images severely degraded to fit within size limit. Download the full paper from http://www.astro.princeton.edu/~krumholz/recent.htm

How will Brexit affect health and health services in the UK? Evaluating three possible scenarios against the WHO health system building blocks

The process of leaving the European Union (EU) will have profound consequences for health and the National Health Service (NHS) in the UK. In this paper, we use the WHO health system building blocks framework to assess the likely effects of three scenarios we term soft Brexit, hard Brexit, and failed Brexit. We conclude that each scenario poses substantial threats. The workforce of the NHS is heavily reliant on EU staff. Financing of health care for UK citizens in the EU and vice versa is threatened, as is access to some capital funds, while Brexit threatens overall economic performance. Access to pharmaceuticals, technology, blood, and organs for transplant is jeopardised. Information used for international comparisons is threatened, as is service delivery, especially in Northern Ireland. Governance concerns relate to public health, competition and trade law, and research. However, we identified a few potential opportunities for improvement in areas such as competition law and flexibility of training, should the UK Government take them. Overall, a soft version of Brexit would minimise health threats whereas failed Brexit would be the riskiest outcome. Effective parliamentary scrutiny of policy and legal changes will be essential, but the scale of the task risks overwhelming parliament and the civil service

How will Brexit affect health services in the UK? An updated evaluation

All forms of Brexit are bad for health, but some are worse than others. This paper builds on our 2017 analysis using the WHO health system building blocks framework to assess the likely effects of Brexit on the National Health Service (NHS) in the UK. We consider four possible scenarios as follows: a No-Deal Brexit under which the UK leaves the EU on March 29, 2019, without any formal agreement on the terms of withdrawal; a Withdrawal Agreement, as negotiated between the UK and EU and awaiting (possible) formal agreement, which provides a transition period until the end of December, 2020; the Northern Ireland Protocol's backstop coming into effect after the end of that period; or the Political Declaration on the Future Relationship between the UK and EU. Our analysis shows that a No-Deal Brexit is substantially worse for the NHS than a future involving the Withdrawal Agreement, which provides certainty and continuity in legal relations while the Political Declaration on the Future Relationship is negotiated and put into legal form. The Northern Ireland backstop has varying effects, with continuity in some areas, such as health products, but no continuity in others. The Political Declaration on the Future Relationship envisages a relationship that is centred around a free-trade agreement, in which wider health-related issues are largely absent. All forms of Brexit, however, involve negative consequences for the UK's leadership and governance of health, in both Europe and globally, with questions about the ability of parliament and other stakeholders to scrutinise and oversee government actions

Assessing the potential impact on health of the UK's future relationship agreement with the EU : analysis of the negotiating positions.

While policy attention is understandably diverted to COVID-19, the end of the UK's post-Brexit ‘transition period’ remains 31 December 2020. All forms of future EU−UK relationship are worse for health than EU membership, but analysis of the negotiating texts shows some forms are better than others. The likely outcomes involve major negative effects for NHS staffing, funding for health and social care, and capital financing for the NHS; and for UK global leadership and influence. We expect minor negative effects for cross border healthcare (except in Northern Ireland); research collaboration; and data sharing, such as the Early Warning and Response System for health threats. Despite political narratives, the legal texts show that the UK seeks de facto continuity in selected key areas for pharmaceuticals, medical devices, and equipment [including personal protective equipment (PPE)], especially clinical trials, pharmacovigilance, and batch-testing. The UK will be excluded from economies of scale of EU membership, e.g. joint procurement programmes as used recently for PPE. Above all, there is a major risk of reaching an agreement with significant adverse effects for health, without meaningful oversight by or input from the UK Parliament, or other health policy stakeholders

Hot high-mass accretion disk candidates

To better understand the physical properties of accretion disks in high-mass star formation, we present a study of a 12 high-mass accretion disk candidates observed at high spatial resolution with the Australia Telescope Compact Array (ATCA) in the NH3 (4,4) and (5,5) lines. Almost all sources were detected in NH3, directly associated with CH3OH Class II maser emission. From the remaining eleven sources, six show clear signatures of rotation and/or infall motions. These signatures vary from velocity gradients perpendicular to the outflows, to infall signatures in absorption against ultracompact HII regions, to more spherical infall signatures in emission. Although our spatial resolution is ~1000AU, we do not find clear Keplerian signatures in any of the sources. Furthermore, we also do not find flattened structures. In contrast to this, in several of the sources with rotational signatures, the spatial structure is approximately spherical with sizes exceeding 10^4 AU, showing considerable clumpy sub-structure at even smaller scales. This implies that on average typical Keplerian accretion disks -- if they exist as expected -- should be confined to regions usually smaller than 1000AU. It is likely that these disks are fed by the larger-scale rotating envelope structure we observe here. Furthermore, we do detect 1.25cm continuum emission in most fields of view.Comment: 21 pages, 32 figures, accepted for ApJS. A high-resolution version can be found at http://www.mpia.de/homes/beuther/papers.htm

Infall of gas as the formation mechanism of stars up to 20 times more massive than the Sun

Theory predicts and observations confirm that low-mass stars (like the Sun) in their early life grow by accreting gas from the surrounding material. But for stars ~ 10 times more massive than the Sun (~10 M_sun), the powerful stellar radiation is expected to inhibit accretion and thus limit the growth of their mass. Clearly, stars with masses >10 M_sun exist, so there must be a way for them to form. The problem may be solved by non-spherical accretion, which allows some of the stellar photons to escape along the symmetry axis where the density is lower. The recent detection of rotating disks and toroids around very young massive stars has lent support to the idea that high-mass (> 8 M_sun) stars could form in this way. Here we report observations of an ammonia line towards a high-mass star forming region. We conclude from the data that the gas is falling inwards towards a very young star of ~20 M_sun, in line with theoretical predictions of non-spherical accretion.Comment: 11 pages, 2 figure

New Debris Disks Around Nearby Main Sequence Stars: Impact on The Direct Detection of Planets

Using the MIPS instrument on the Spitzer telescope, we have searched for infrared excesses around a sample of 82 stars, mostly F, G, and K main-sequence field stars, along with a small number of nearby M stars. These stars were selected for their suitability for future observations by a variety of planet-finding techniques. These observations provide information on the asteroidal and cometary material orbiting these stars - data that can be correlated with any planets that may eventually be found. We have found significant excess 70um emission toward 12 stars. Combined with an earlier study, we find an overall 70um excess detection rate of $13 \pm 3$% for mature cool stars. Unlike the trend for planets to be found preferentially toward stars with high metallicity, the incidence of debris disks is uncorrelated with metallicity. By newly identifying 4 of these stars as having weak 24um excesses (fluxes $\sim$10% above the stellar photosphere), we confirm a trend found in earlier studies wherein a weak 24um excess is associated with a strong 70um excess. Interestingly, we find no evidence for debris disks around 23 stars cooler than K1, a result that is bolstered by a lack of excess around any of the 38 K1-M6 stars in 2 companion surveys. One motivation for this study is the fact that strong zodiacal emission can make it hard or impossible to detect planets directly with future observatories like the {\it Terrestrial Planet Finder (TPF)}. The observations reported here exclude a few stars with very high levels of emission, $>$1,000 times the emission of our zodiacal cloud, from direct planet searches. For the remainder of the sample, we set relatively high limits on dust emission from asteroid belt counterparts

The Formation of the First Low-Mass Stars From Gas With Low Carbon and Oxygen Abundances

The first stars in the Universe are predicted to have been much more massive than the Sun. Gravitational condensation accompanied by cooling of the primordial gas due to molecular hydrogen, yields a minimum fragmentation scale of a few hundred solar masses. Numerical simulations indicate that once a gas clump acquires this mass, it undergoes a slow, quasi-hydrostatic contraction without further fragmentation. Here we show that as soon as the primordial gas - left over from the Big Bang - is enriched by supernovae to a carbon or oxygen abundance as small as ~0.01-0.1% of that found in the Sun, cooling by singly-ionized carbon or neutral oxygen can lead to the formation of low-mass stars. This mechanism naturally accommodates the discovery of solar mass stars with unusually low (10^{-5.3} of the solar value) iron abundance but with a high (10^{-1.3} solar) carbon abundance. The minimum stellar mass at early epochs is partially regulated by the temperature of the cosmic microwave background. The derived critical abundances can be used to identify those metal-poor stars in our Milky Way galaxy with elemental patterns imprinted by the first supernovae.Comment: 14 pages, 2 figures (appeared today in Nature

Reducing Zero-point Systematics in Dark Energy Supernova Experiments

We study the effect of filter zero-point uncertainties on future supernova dark energy missions. Fitting for calibration parameters using simultaneous analysis of all Type Ia supernova standard candles achieves a significant improvement over more traditional fit methods. This conclusion is robust under diverse experimental configurations (number of observed supernovae, maximum survey redshift, inclusion of additional systematics). This approach to supernova fitting considerably eases otherwise stringent mission calibration requirements. As an example we simulate a space-based mission based on the proposed JDEM satellite; however the method and conclusions are general and valid for any future supernova dark energy mission, ground or space-based.Comment: 30 pages,8 figures, 5 table, one reference added, submitted to Astroparticle Physic