Direct Detection of Galactic Halo Dark Matter

The Milky Way Galaxy contains a large, spherical component which is believed to harbor a substantial amount of unseen matter. Recent observations indirectly suggest that as much as half of this ``dark matter'' may be in the form of old, very cool white dwarfs, the remnants of an ancient population of stars as old as the Galaxy itself. We conducted a survey to find faint, cool white dwarfs with large space velocities, indicative of their membership in the Galaxy's spherical halo component. The survey reveals a substantial, directly observed population of old white dwarfs, too faint to be seen in previous surveys. This newly discovered population accounts for at least 2% of the halo dark matter. It provides a natural explanation for the indirect observations, and represents a direct detection of Galactic halo dark matter.Comment: 13 pages, 4 figures, 1 table. Note added after Science Express online publication: This text reflects the correction of a few typographical errors in the online version of the table. It also includes the new constraint on the calculation of d_max which accounts for the fact that the survey could not have detected stars with proper motions below 0.33 arcseconds per year. Published online at ScienceExpress www.sciencemag.org 22 March 2001; 10.1126/science.1059954; To appear in Science 27 April 200

Faecal haemoglobin can define risk of colorectal neoplasia at surveillance colonoscopy in patients at increased risk of colorectal cancer.

Background: Quantitative faecal immunochemical tests measure faecal haemoglobin concentration (f-Hb), which increases in the presence of colorectal neoplasia.Objective: We examined the diagnostic accuracy of faecal immunochemical test (FIT)in patients at increased risk of colorectal cancer (CRC) attending for surveillance colonoscopy as per national guidelines.Methods: A total of 1103 consecutive patients were prospectively invited to complete a FIT before their scheduled colonoscopy in two university hospitals in 2014– 2016. F-Hb was analysed on an OC-Sensor io automated analyser (Eiken Chemical Co., Ltd, Tokyo, Japan) with a limit of detection of 2 µg Hb/g faeces. The diagnostic accuracy of f-Hb for CRC and higher-risk adenoma was examined.Results: A total of 643 patients returned a faecal test. After excluding 4 patients with known inflammatory bowel disease, 639 (57.9%) remained in the study: age range: 25–90 years (median: 64 years, interquartile range (IQR): 55–71): 54.6% male. Of 593 patients who also completed colonoscopy, 41 (6.9%) had advanced neoplasia (4 CRC, 37 higher-risk adenoma). Of the 238 patients (40.1%) who had detectable f-Hb, 31 (13.0%) had advanced neoplasia (2 CRC, 29 higher-risk adenoma) compared with 10 (2.8%) in those with undetectable f-Hb (2 CRC, 8 higher-risk adenoma). Detectable f-Hb gave negative predictive values of 99.4% for CRC and 97.2% for CRC plus higher-risk adenoma.Conclusion: In patients at increased risk of CRC under colonoscopy surveillance, a test measuring faecal haemoglobin can provide an objective estimate of the risk of advanced neoplasia, and could enable tailored scheduling of colonoscopy.</p

SSSPM J1444-2019: an extremely high proper motion, ultracool subdwarf

We present the discovery of a new extreme high proper motion object (3.5 arcsec/year) which we classify as an ultracool subdwarf with [M/H] = -0.5. It has a formal spectral type of sdM9 but also shows L-type features: while the VO bands are completely absent, it exhibits extremely strong TiO absorption in its optical spectrum. With a radial velocity of about -160 km/s and a rough distance estimate of 16--24 pc, it is likely one of the nearest halo members crossing the Solar neighbourhood with a heliocentric space velocity of (U,V,W)=(-244,-256,-100)+/-(32,77,6) km/s.Comment: 4 pages, 4 figures (Fig.1a-d available as jpg files), accepted for publication in Astronomy & Astrophysics Letter

Communicating REDD+ Issues at Local Level: Creating Latent and Manifest Conflict

”Carbon offsetting”in forestry-related projects is widely regarded as the ideal solution to the three challenges of the 21st Century: climate change, biodiversity conservation andsocio-economic development. At the same time, there is scepticism about the Reducing Emissions from Deforestation and Forest Degradation (REDD) proposal particularly because of the weak governance and institutional capacities in many developing countries, which could jeopardize the delivery of benefits at the local level. One major problem is that most people have little knowledge on the causes and consequences of the climate change. This is partly because the information is largely scattered among scientific journals, and obscured by jargon and sophisticated mathematical models. Consequently, REDD+ is beyond thereach of manyof the people affected by REDD+. This paper examines the efforts and the capacity of the local governments and other development agents in explaining the REDD + issues and its impacts on the local people, especially customary communities. The research shows that lack of policy communication and promotion, as well as consultations with the affected groups arethe main contributing factors to latent and manifest conflicts. In turn, this conflicth as proven that NGOs, district governments and scientists have not been successful intermediaries. Thus, in the future policy communication on REDD+ should beaimed at improved network formation (i.e. between farmer groups with business partners and NGOs and other related actors), learning, negotiation and relationship building (i.e. between members of farmer groups, not only withtheir leaders within the farmer groups but also with governmental and business sectors). Policy communication should also create a new configuration of support and services in form of advocacy, empowerment and management skills and technical skills for conserving their natural resources, for adaptation to climate change and building more equitable governance and transparency at local level

Granular Packings: Nonlinear elasticity, sound propagation and collective relaxation dynamics

Experiments on isotropic compression of a granular assembly of spheres show that the shear and bulk moduli vary with the confining pressure faster than the 1/3 power law predicted by Hertz-Mindlin effective medium theories (EMT) of contact elasticity. Moreover, the ratio between the moduli is found to be larger than the prediction of the elastic theory by a constant value. The understanding of these discrepancies has been a longstanding question in the field of granular matter. Here we perform a test of the applicability of elasticity theory to granular materials. We perform sound propagation experiments, numerical simulations and theoretical studies to understand the elastic response of a deforming granular assembly of soft spheres under isotropic loading. Our results for the behavior of the elastic moduli of the system agree very well with experiments. We show that the elasticity partially describes the experimental and numerical results for a system under compressional loads. However, it drastically fails for systems under shear perturbations, particularly for packings without tangential forces and friction. Our work indicates that a correct treatment should include not only the purely elastic response but also collective relaxation mechanisms related to structural disorder and nonaffine motion of grains.Comment: 21 pages, 13 figure

MammoSapiens: eResearch of the lactation program. Building online facilities for collaborative molecular and evolutionary analysis of lactation and other biological systems from gene sequences and gene expression data.

Delivering bioinformatics power to life science researchers inevitably runs into problems of limited computing resources in the context of exponentially increasing data sources, access time, costs, lack of skills and, rapidly evolving technology and software tools with poorly defined standards. In this context the development of online facilities to best enable collaborative research often needs to be customized to specific project applications in close cooperation with the experimentalist users and, to be concerned with the storage and management of results to allow more consistency and traceability of results on a broad access data mining platform. Here we showcase an Internet based research platform using the PHP/MySQL paradigm for the collaborative, integrative and comparative analysis of lactation related gene sequences and gene expression experiments to support lactation research. We also illustrate how these resources are used, how they enable research by allowing meta-analysis of data and results and, how the bottom-up development of customized eResearch components can lead to the production of more generic functional software tools and eResearch environments for deployment to a larger number of biological researchers working on other bio-systems

Pressure dependence of the sound velocity in a 2D lattice of Hertz-Mindlin balls: a mean field description

We study the dependence on the external pressure $P$ of the velocities $v_{L,T}$ of long wavelength sound waves in a confined 2D h.c.p. lattice of 3D elastic frictional balls interacting via one-sided Hertz-Mindlin contact forces, whose diameters exhibit mild dispersion. The presence of an underlying long range order enables us to build an effective medium description which incorporates the radial fluctuations of the contact forces acting on a single site. Due to the non linearity of Hertz elasticity, self-consistency results in a highly non-linear differential equation for the "equation of state" linking the effective stiffness of the array with the applied pressure, from which sound velocities are then obtained. The results are in excellent agreement with existing experimental results and simulations in the high and intermediate pressure regimes. It emerges from the analysis that the departure of $v_{L}(P)$ from the ideal $P^{1/6}$ Hertz behavior must be attributed primarily to the fluctuations of the stress field, rather than to the pressure dependence of the number of contacts

The Lyot Project Direct Imaging Survey of Substellar Companions: Statistical Analysis and Information from Nondetections

The Lyot project used an optimized Lyot coronagraph with Extreme Adaptive Optics at the 3.63m Advanced Electro-Optical System telescope (AEOS) to observe 86 stars from 2004 to 2007. In this paper we give an overview of the survey results and a statistical analysis of the observed nondetections around 58 of our targets to place constraints on the population of substellar companions to nearby stars. The observations did not detect any companion in the substellar regime. Since null results can be as important as detections, we analyzed each observation to determine the characteristics of the companions that can be ruled out. For this purpose we use a Monte Carlo approach to produce artificial companions, and determine their detectability by comparison with the sensitivity curve for each star. All the non-detection results are combined using a Bayesian approach and we provide upper limits on the population of giant exoplanets and brown dwarfs for this sample of stars. Our nondetections confirm the rarity of brown dwarfs around solar-like stars and we constrain the frequency of massive substellar companions (M>40Mjup) at orbital separation between and 10 and 50 AU to be <20%.Comment: 32 pages, 11 figures, 2 tables. Published in the Astrophysical Journa