Identification of Aloes in East Africa

Volume: XXV

The influence of non-CO2 forcings on cumulative carbon emissions budgets

Carbon budgets provide a useful tool for policymakers to help meet the global climate targets, as they specify total allowable carbon emissions consistent with limiting warming to a given temperature threshold. Non-CO _2 forcings have a net warming effect in the Representative Concentration Pathways (RCP) scenarios, leading to reductions in remaining carbon budgets based on CO _2 forcing alone. Carbon budgets consistent with limiting warming to below 2.0 °C, with and without accounting for the effects of non-CO _2 forcings, were assessed in inconsistent ways by the Intergovernmental Panel on Climate Change (IPCC), making the effects of non-CO _2 forcings hard to identify. Here we use a consistent approach to compare 1.5 °C and 2.0 °C carbon budgets with and without accounting for the effects of non-CO _2 forcings, using CO _2 -only and RCP8.5 simulations. The median allowable carbon budgets for 1.5 °C and 2.0 °C warming are reduced by 257 PgC and 418 PgC, respectively, and the uncertainty ranges on the budgets are reduced by more than a factor of two when accounting for the net warming effects of non-CO _2 forcings. While our overall results are consistent with IPCC, we use a more robust methodology, and explain the narrower uncertainty ranges of carbon budgets when non-CO _2 forcings are included. We demonstrate that most of the reduction in carbon budgets is a result of the direct warming effect of the non-CO _2 forcings, with a secondary contribution from the influence of the non-CO _2 forcings on the carbon cycle. Such carbon budgets are expected to play an increasingly important role in climate change mitigation, thus understanding the influence of non-CO _2 forcings on these budgets and their uncertainties is critical

Experimental feedback control of quantum systems using weak measurements

A goal of the emerging field of quantum control is to develop methods for quantum technologies to function robustly in the presence of noise. Central issues are the fundamental limitations on the available information about quantum systems and the disturbance they suffer in the process of measurement. In the context of a simple quantum control scenario--the stabilization of non-orthogonal states of a qubit against dephasing--we experimentally explore the use of weak measurements in feedback control. We find that, despite the intrinsic difficultly of implementing them, weak measurements allow us to control the qubit better in practice than is even theoretically possible without them. Our work shows that these more general quantum measurements can play an important role for feedback control of quantum systems.Comment: 4 pages, 3 figures. v2 Added extra citation, journal reference and DOI. Minor typographic correction

Thirty Meter Telescope Site Testing I: Overview

As part of the conceptual and preliminary design processes of the Thirty Meter Telescope (TMT), the TMT site testing team has spent the last five years measuring the atmospheric properties of five candidate mountains in North and South America with an unprecedented array of instrumentation. The site testing period was preceded by several years of analyses selecting the five candidates, Cerros Tolar, Armazones and Tolonchar in northern Chile; San Pedro Martir in Baja California, Mexico and the 13 North (13N) site on Mauna Kea, Hawaii. Site testing was concluded by the selection of two remaining sites for further consideration, Armazones and Mauna Kea 13N. It showed that all five candidates are excellent sites for an extremely large astronomical observatory and that none of the sites stands out as the obvious and only logical choice based on its combined properties. This is the first article in a series discussing the TMT site testing project.Comment: Accepted for publication in PASP, April 2009 issu

Truth-telling to the patient, family, and the sexual partner: a rights approach to the role of healthcare providers in adult HIV disclosure in China.

Patients' rights are central in today's legislation and social policies related to health care, including HIV care, in not only Western countries but around the world. However, given obvious socio-cultural differences it is often asked how or to what extent patients' rights should be respected in non-Western societies such as China. In this paper, it is argued that the patients' rights framework is compatible with Chinese culture, and that from the perspective of contemporary patient rights healthcare providers have a duty to disclose truthfully the diagnosis and prognosis to their patients, that the Chinese cultural practice of involving families in care should - with consent from the patient - be promoted out of respect for patients' rights and well-being, and that healthcare providers should be prepared to address the issue of disclosing a patient's HIV status to sexual partner(s). Legally, the provider should be permitted to disclose without consent from the patient but not obliged to in all cases. The decision to do this should be taken with trained sensitivity to a range of ethically relevant considerations. Post-disclosure counseling or psychological support should be in place to address the concerns of potentially adverse consequences of provider-initiated disclosure and to maximize the psychosocial and medical benefits of the disclosure. There is an urgent need for healthcare providers to receive training in ethics and disclosure skills. This paper concludes also with some suggestions for improving the centerpiece Chinese legislation, State Council's "Regulations on AIDS Prevention and Control" (2006), to further safeguard the rights and well-being of HIV patients

Modeling the climate impact of Southern Hemisphere ozone depletion:the importance of the ozone dataset

The ozone hole is an important driver of recent Southern Hemisphere (SH) climate change, and capturing these changes is a goal of climate modeling. Most climate models are driven by off-line ozone data sets. Previous studies have shown that there is a substantial range in estimates of SH ozone depletion, but the implications of this range have not been examined systematically. We use a climate model to evaluate the difference between using the ozone forcing (Stratospheric Processes and their Role in Climate (SPARC)) used by many Intergovernmental Panel on Climate Change Fifth Assessment Report (Coupled Model Intercomparison Project) models and one at the upper end of the observed depletion estimates (Binary Database of Profiles (BDBP)). In the stratosphere, we find that austral spring/summer polar cap cooling, geopotential height decreases, and zonal wind increases in the BDBP simulations are all doubled compared to the SPARC simulations, while tropospheric responses are 20–100% larger. These results are important for studies attempting to diagnose the climate fingerprints of ozone depletion

The optical/infrared counterpart(s) of IRAS 18333-2357

Observations of the potential optical counterparts of the unusual source IRAS 18333-2357 show that this source is associated with an extraordinary planetary nebula system in the galactic globular cluster M22. Three distinct optical objects were found within 2" of the IRAS 18333-2357 position as determined by precisely locating the 20 μm infrared source. One object is a red star with m_v ≈ 14.7 mag, which appears to be an unrelated background field star that is possibly significantly reddened beyond the line-of-sight reddening to M22. The second stellar object is a very blue star with m_v ≈ 14.3 mag located about 1~3 south of the red star. Absorption lines of He 11 and possibly H are present in 4000-5000 A spectra of the stellar pair, similar to spectra of planetary nebula nuclei. The third member of this optical triple is an extended emission line nebulosity approximately 10" x 7" in size, centered about 1" east and south of the red star. The ionized gas in this nebulosity is extraordinarily oxygen-rich and neon-rich relative to both hydrogen and helium compared to the atmospheres of M22 red giants and is substantially oxygen-rich and neon-rich relative to hydrogen in comparison with typical planetary nebulae. This nebulosity is almost certainly in M22. The blue star is also very likely to be a member of M22, the source of ionizing photons for the nebulosity and probably the luminosity source for IRAS 18333-2357. We suggest that the dust responsible for the strong infrared emission of IRAS 18333-2357 is physically associated with the M22 nebulosity. In this case the total nebular mass, comprised of 3-10 x 10^(-4) M_☉ of ionized gas plus > 6 x 10^(-4) M_☉ of silicate or carbon-based grains, is possibly dominated by the dust component. The 0, Mg, Si abundances in the case of silicate grains, or carbon in the case of carbon-based grains, may be enhanced relative to hydrogen by at least a factor of 1000 compared to solar abundances. The relative abundances and mass of the M22 nebula are very unusual among known planetary nebulae. It is speculated that this system in M22 may be the result of the interaction within a close binary system containing at least one 0-Ne white dwarf component, or perhaps related to planetary nebulae like A30 and A78