541 research outputs found
Range contraction to a higher elevation: the likely future of the montane vegetation in South Africa and Lesotho
Global climate change is a major challenge for the future with serious potential impacts on biodiversity. Biodiversity in mountains is particularly vulnerable as many montane species are adapted to narrow microhabitats, making them less able to adjust to a climatic
change. It is considered important to investigate range changes in the South African Great Escarpment because of the high levels of biodiversity in these mountains, as well as their importance for water provision in South Africa. The current and future ranges of 46 montane plant species in South Africa and Lesotho were therefore modelled using biomod in R, using presence points and predictor variables which included rainfall and temperature worldclim layers. The performance of distribution models produced was evaluated using the Area Under the receiver operating Curve (AUC), True Skill Statistic (TSS), Sensitivity and Specificity. We calculated beta diversity and species richness changes between current and future climates for the group of 46 species, as well as shifts of the predicted presence region boundaries and centroids. We also analysed shifts in minimum, median and maximum elevations. Results show a contraction in speciesâ ranges towards higher elevation as has been documented from other mountain regions around the world. These results are a cause for concern as a warming climate is decreasing the potential regions of occurrence of montane species in South Africa and Lesothoâs mountainous regions of high biodiversity. This region is under a diverse range of conservation and land use management practises, and our results suggest a coordinated response to climate change is needed
A Compact 3H(p,gamma)4He 19.8-MeV Gamma-Ray Source for Energy Calibration at the Sudbury Neutrino Observatory
The Sudbury Neutrino Observatory (SNO) is a new 1000-tonne D2O Cerenkov solar
neutrino detector. A high energy gamma-ray source is needed to calibrate SNO
beyond the 8B solar neutrino endpoint of 15 MeV. This paper describes the
design and construction of a source that generates 19.8-MeV gamma rays using
the 3H(p,gamma)4He reaction (``pt''), and demonstrates that the source meets
all the physical, operational and lifetime requirements for calibrating SNO. An
ion source was built into this unit to generate and to accelerate protons up to
30 keV, and a high purity scandium tritide target with a scandium-tritium
atomic ratio of 1:2.0+/-0.2 was included. This pt source is the first
self-contained, compact, and portable high energy gamma-ray source (E>10 MeV).Comment: 33 pages (including 2 table, 12 figures) This is the revised
manuscript, accepted for publication in NIM A. This revision relfects minor
editorial changes from the previous versio
Diffuse Neutron Scattering Study of a Disordered Complex Perovskite Pb(Zn1/3Nb2/3)O3 Crystal
Diffuse scattering around the (110) reciprocal lattice point has been
investigated by elastic neutron scattering in the paraelectric and the relaxor
phases of the disordered complex perovskite crystal-Pb(Zn1/3Nb2/3)O3(PZN). The
appearance of a diffuse intensity peak indicates the formation of polar
nanoregions at temperature T*, approximately 40K above Tc=413K. The analysis of
this diffuse scattering indicates that these regions are in the shape of
ellipsoids, more extended in the direction than in the direction.
The quantitative analysis provides an estimate of the correlation length, \xi,
or size of the regions and shows that \xi ~1.2\xi , consistent with
the primary or dominant displacement of Pb leading to the low temperature
rhombohedral phase. Both the appearance of the polar regions at T*and the
structural transition at Tc are marked by kinks in the \xi curve but not
in the \xi one, also indicating that the primary changes take place in a
direction at both temperatures.Comment: REVTeX file. 4 pages, 3 figures embedded, New version after referee
cond-mat/010605
Child caries management: A randomized controlled trial in dental practice
This multicenter 3-arm, parallel-group, patient-randomized controlled trial compared clinical effectiveness of 3 treatment strategies over 3 y for managing dental caries in primary teeth in UK primary dental care. Participants aged 3 to 7 y with at least 1 primary molar with dentinal carious lesion were randomized across 3 arms (1:1:1 via centrally administered system with variable-length random permuted blocks): C+P, conventional carious lesion management (complete carious tooth tissue removal and restoration placement) with prevention; B+P, biological management (sealing in carious tooth tissue restoratively) with prevention; and PA, prevention alone (diet, plaque removal, fluorides, and fissure sealants). Parents, children, and dentists were not blind to allocated arm. Coâprimary outcomes were 1) the proportion of participants with at least 1 episode of dental pain and/or infection and 2) the number of episodes of dental pain and/or infection during follow-up (minimum, 23 mo). In sum, 1,144 participants were randomized (C+P, n = 386; B+P, n = 381; PA, n = 377) by 72 general dental practitioners, of whom 1,058 (C+P, n = 352; B+P, n = 352; PA, n = 354) attended at least 1 study visit and were included in the primary analysis. The median follow-up was 33.8 mo (interquartile range, 23.8 to 36.7). Proportions of participants with at least 1 episode of dental pain and/or infection were as follows: C+P, 42%; B+P, 40%; PA, 45%. There was no evidence of a difference in incidence of dental pain and/or infection when B+P (adjusted risk difference [97.5% CI]: â2% [â10% to 6%]) or PA (4% [â4% to 12%]) was compared with C+P. The mean (SD) number of episodes of dental pain and/or infection were as follows: C+P, 0.62 (0.95); B+P, 0.58 (0.87); and PA, 0.72 (0.98). Superiority could not be concluded for number of episodes between B+P (adjusted incident rate ratio (97.5% CI): 0.95 [0.75 to 1.21]) or PA (1.18 [0.94 to 1.48]) and C+P. In conclusion, there was no evidence of a difference among the 3 treatment approaches for incidence or number of episodes of dental pain and/or infection experienced by these participants with high caries risk and established disease (trial registration: ISRCTN77044005)
Completion of Advance Directives: Do Social Work Preadmission Interviews Make a Difference?
Objectives: This study tests the efficacy of a preadmission, educational interview on advance directives, in this case, health care proxies (HCPs) offered to elective, orthopedic patients. Method: Using a quasi-experimental design, participants (n = 54) are assigned to either treatment group (who received the educational interview, conducted by a social worker, over and above the federally mandated written information on HCPs) or comparison group (who received the written information only). Results: Logistic regression analysis indicates there is a statistically significantly higher probability that a patient would sign an HCP if assigned to the treatment group than if assigned to the comparison condition. Conclusion: Benefits of educating patients about HCPs as part of routine social work practice are outlined
Statistical disclosure control in tabular data
Data disseminated by National Statistical Agencies (NSAs) can be classified
as either microdata or tabular data. Tabular data is obtained from microdata by
crossing one or more categorical variables. Although cell tables provide aggregated
information, they also need to be protected. This chapter is a short introduction to
tabular data protection. It contains three main sections. The first one shows the different
types of tables that can be obtained, and how they are modeled. The second
describes the practical rules for detection of sensitive cells that are used by NSAs.
Finally, an overview of protection methods is provided, with a particular focus on
two of them: âcell suppression problemâ and âcontrolled tabular adjustmentâ.Postprint (published version
An Integrated TCGA Pan-Cancer Clinical Data Resource to Drive High-Quality Survival Outcome Analytics
For a decade, The Cancer Genome Atlas (TCGA) program collected clinicopathologic annotation data along with multi-platform molecular profiles of more than 11,000 human tumors across 33 different cancer types. TCGA clinical data contain key features representing the democratized nature of the data collection process. To ensure proper use of this large clinical dataset associated with genomic features, we developed a standardized dataset named the TCGA Pan-Cancer Clinical Data Resource (TCGA-CDR), which includes four major clinical outcome endpoints. In addition to detailing major challenges and statistical limitations encountered during the effort of integrating the acquired clinical data, we present a summary that includes endpoint usage recommendations for each cancer type. These TCGA-CDR findings appear to be consistent with cancer genomics studies independent of the TCGA effort and provide opportunities for investigating cancer biology using clinical correlates at an unprecedented scale. Analysis of clinicopathologic annotations for over 11,000 cancer patients in the TCGA program leads to the generation of TCGA Clinical Data Resource, which provides recommendations of clinical outcome endpoint usage for 33 cancer types
Climatic effects on sugarcane ripening under the influence of cultivars and crop age
The lack of information about the effects of cultivars, crop age and climate on the sugarcane (Saccharum ssp.) crop yield and quality has been the primary factor impacting the sugar-ethanol sector in Brazil. One of the processes about which we do not have a satisfactory understanding is sugarcane ripening and the effects of cultivars, crop age and climate on that. Sugarcane ripening is the process of sucrose accumulation in stalks, which is heavily influenced by several factors, mainly by climatic conditions such as air temperature and water deficits. Because it is a complex process, studies of the variables involved in sugarcane ripening can provide important information, resulting in a better use of commercial cultivars, bringing advantages to growers, processing units, breeding programs and scientific community. In this review, we discuss the available knowledge of the interaction between climate conditions and sugarcane ripening, under the influence of genotypic characteristics and crop age. In several studies, the main conclusion is that sugarcane ripening depends on a complex combination of climate variables, the genetic potential of cultivars and crop management. Soil moisture and air temperature are the primary variables involved in sugarcane ripening, and their combination stimulates the intensity of the process. In addition, the need for studies integrating the effects of climate on plant physiological processes and on the use of chemical agents to stimulate sugarcane ripening is highlighted
Search for displaced vertices arising from decays of new heavy particles in 7 TeV pp collisions at ATLAS
We present the results of a search for new, heavy particles that decay at a
significant distance from their production point into a final state containing
charged hadrons in association with a high-momentum muon. The search is
conducted in a pp-collision data sample with a center-of-mass energy of 7 TeV
and an integrated luminosity of 33 pb^-1 collected in 2010 by the ATLAS
detector operating at the Large Hadron Collider. Production of such particles
is expected in various scenarios of physics beyond the standard model. We
observe no signal and place limits on the production cross-section of
supersymmetric particles in an R-parity-violating scenario as a function of the
neutralino lifetime. Limits are presented for different squark and neutralino
masses, enabling extension of the limits to a variety of other models.Comment: 8 pages plus author list (20 pages total), 8 figures, 1 table, final
version to appear in Physics Letters
Measurement of the polarisation of W bosons produced with large transverse momentum in pp collisions at sqrt(s) = 7 TeV with the ATLAS experiment
This paper describes an analysis of the angular distribution of W->enu and
W->munu decays, using data from pp collisions at sqrt(s) = 7 TeV recorded with
the ATLAS detector at the LHC in 2010, corresponding to an integrated
luminosity of about 35 pb^-1. Using the decay lepton transverse momentum and
the missing transverse energy, the W decay angular distribution projected onto
the transverse plane is obtained and analysed in terms of helicity fractions
f0, fL and fR over two ranges of W transverse momentum (ptw): 35 < ptw < 50 GeV
and ptw > 50 GeV. Good agreement is found with theoretical predictions. For ptw
> 50 GeV, the values of f0 and fL-fR, averaged over charge and lepton flavour,
are measured to be : f0 = 0.127 +/- 0.030 +/- 0.108 and fL-fR = 0.252 +/- 0.017
+/- 0.030, where the first uncertainties are statistical, and the second
include all systematic effects.Comment: 19 pages plus author list (34 pages total), 9 figures, 11 tables,
revised author list, matches European Journal of Physics C versio
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