38 research outputs found
The Spitzer c2d Survey of Nearby Dense Cores. V. Discovery of a VeLLO in the "Starless" Dense Core L328
This paper reports the discovery of a Very Low Luminosity Object (VeLLO) in
the "starless" dense core L328, using the Spitzer Space Telescope and ground
based observations from near-infrared to millimeter wavelengths. The Spitzer 8
micron image indicates that L328 consists of three subcores of which the
smallest one may harbor a source, L328-IRS while two other subcores remain
starless. L328-IRS is a Class 0 protostar according to its bolometric
temperature (44 K) and the high fraction ~72 % of its luminosity emitted at
sub-millimeter wavelengths. Its inferred "internal luminosity" (0.04 - 0.06
Lsun) using a radiative transfer model under the most plausible assumption of
its distance as 200 pc is much fainter than for a typical protostar, and even
fainter than other VeLLOs studied previously. Note, however, that its inferred
luminosity may be uncertain by a factor of 2-3 if we consider two extreme
values of the distance of L328-IRS (125 or 310 pc). Low angular resolution
observations of CO do not show any clear evidence of a molecular outflow
activity. But broad line widths toward L328, and Spitzer and near-infrared
images showing nebulosity possibly tracing an outflow cavity, strongly suggest
the existence of outflow activity. Provided that an envelope of at most ~0.1
Msunis the only mass accretion reservoir for L328-IRS, and the star formation
efficiency is close to the canonical value ~30%, L328-IRS has not yet accreted
more than 0.05 Msun. At the assumed distance of 200 pc, L328-IRS is destined to
be a brown dwarf.Comment: 29 pages, 8 figures, 1 table, to be published in Astrophysical
Journa
Bridging the Gap Between Stars and Planets: The Formation and Early Evolution of Brown Dwarfs
This White Paper, submitted to the National Academy of Sciences' Astro2010
Decadal Review Committee, focuses on 2 central themes in the study of young
brown dwarfs -- their formation mechanism and disk characteristics -- which are
of direct relevance to fundamental questions of stellar and planetary origins
and properties.Comment: 8 pages, 3 figures, Astro2010 Science White Paper (v2 has 2
references corrected/updated, and 3 repeated references in the v1 reference
list removed
National Guidelines For The Management Of Pain In Older Adults
Consultation Paper- This guidance document reviews the epidemiology and management of pain in older people via a systematic literature review of published research. The aim of this document is to inform any health professionals in any care settings who work with older adults on best practice for the management of pain and to identify any gaps in the evidence which may require further research
Extreme Conservation Leads to Recovery of the Virunga Mountain Gorillas
As wildlife populations are declining, conservationists are under increasing pressure to measure the effectiveness of different management strategies. Conventional conservation measures such as law enforcement and community development projects are typically designed to minimize negative human influences upon a species and its ecosystem. In contrast, we define “extreme” conservation as efforts targeted to deliberately increase positive human influences, including veterinary care and close monitoring of individual animals. Here we compare the impact of both conservation approaches upon the population growth rate of the critically endangered Virunga mountain gorillas (Gorilla beringei beringei), which increased by 50% since their nadir in 1981, from approximately 250 to nearly 400 gorillas. Using demographic data from 1967–2008, we show an annual decline of 0.7%±0.059% for unhabituated gorillas that received intensive levels of conventional conservation approaches, versus an increase 4.1%±0.088% for habituated gorillas that also received extreme conservation measures. Each group of habituated gorillas is now continuously guarded by a separate team of field staff during daylight hours and receives veterinary treatment for snares, respiratory disease, and other life-threatening conditions. These results suggest that conventional conservation efforts prevented a severe decline of the overall population, but additional extreme measures were needed to achieve positive growth. Demographic stochasticity and socioecological factors had minimal impact on variability in the growth rates. Veterinary interventions could account for up to 40% of the difference in growth rates between habituated versus unhabituated gorillas, with the remaining difference likely arising from greater protection against poachers. Thus, by increasing protection and facilitating veterinary treatment, the daily monitoring of each habituated group contributed to most of the difference in growth rates. Our results argue for wider consideration of extreme measures and offer a startling view of the enormous resources that may be needed to conserve some endangered species
Finishing the euchromatic sequence of the human genome
The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead
Many Labs 2: Investigating Variation in Replicability Across Samples and Settings
We conducted preregistered replications of 28 classic and contemporary published findings, with protocols that were peer reviewed in advance, to examine variation in effect magnitudes across samples and settings. Each protocol was administered to approximately half of 125 samples that comprised 15,305 participants from 36 countries and territories. Using the conventional criterion of statistical significance (p < .05), we found that 15 (54%) of the replications provided evidence of a statistically significant effect in the same direction as the original finding. With a strict significance criterion (p < .0001), 14 (50%) of the replications still provided such evidence, a reflection of the extremely highpowered design. Seven (25%) of the replications yielded effect sizes larger than the original ones, and 21 (75%) yielded effect sizes smaller than the original ones. The median comparable Cohen’s ds were 0.60 for the original findings and 0.15 for the replications. The effect sizes were small (< 0.20) in 16 of the replications (57%), and 9 effects (32%) were in the direction opposite the direction of the original effect. Across settings, the Q statistic indicated significant heterogeneity in 11 (39%) of the replication effects, and most of those were among the findings with the largest overall effect sizes; only 1 effect that was near zero in the aggregate showed significant heterogeneity according to this measure. Only 1 effect had a tau value greater than .20, an indication of moderate heterogeneity. Eight others had tau values near or slightly above .10, an indication of slight heterogeneity. Moderation tests indicated that very little heterogeneity was attributable to the order in which the tasks were performed or whether the tasks were administered in lab versus online. Exploratory comparisons revealed little heterogeneity between Western, educated, industrialized, rich, and democratic (WEIRD) cultures and less WEIRD cultures (i.e., cultures with relatively high and low WEIRDness scores, respectively). Cumulatively, variability in the observed effect sizes was attributable more to the effect being studied than to the sample or setting in which it was studied.UCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Sociales::Instituto de Investigaciones Psicológicas (IIP
Portfolio Analysis with the Markowitz Model
Investment counseling and decision making criteria have undergone drastic changes the past two decades--largely due to Harry M. Markowitz. Radical theories of portfolio management have been developed by Markowitz, gaining increased acceptance since their introduction in 1952. Prior to this time rather naive concepts persisted on how to manage a firm\u27s investment portfolio. The investment sector of the financial world was highly dependent upon chartists and technical analysts for input on how to manage portfolios. The dominant philosophy of portfolio management prior to 1952 can be summarized as follows. Emphasis was placed upon the evaluation of individual securities. How securities would perform when combined with one another was not considered. An investment manager looked only at an individual security\u27s potential and past returns and virtually neglected any factor of risk the firm might be exposed to. Evaluation was on securities individually, not on securities together in a portfolio