9,740 research outputs found
A study of global monopole in Lyra geometry
A class of exact static solution around a global monopole resulting from the
breaking of a global S0(3) symmetry is obtained in the context of Lyra
geometry. Our solution is shown to possess an interesting feature like
wormholes space-time. It has been shown that the global monopole exerts no
gravitational force on surrounding non-relativistic matter.Comment: 6 pages, Published in Mod.Phys.Lett.A19:2785-2790,200
Minor millets as a central element for sustainably enhanced incomes, empowerment, and nutrition in rural India
Minor millets comprise a group of cereal species that are genetically diverse and adapted to a range of marginal growing conditions where major cereals such as wheat, rice, and maize are relatively unsuccessful. Millets require few inputs and withstand severe biotic and abiotic stresses. They are also more nutritious than major cereals. Despite these advantages, neglect in several arenas has resulted in a steady decline in the cultivation of minor millets in India over the past few decades. As part of a United Nations global project on underutilized species, we undertook action research intended to stem the decline in cultivation and enhance the conservation and use of minor millets in 753 households spread across 34 villages in four states of India. Our aim was to improve incomes, nutritional status, and empowerment, especially for women. Overall, our holistic approach to mainstreaming species such as finger millet, little millet, foxtail millet, and barnyard millet indicates that these neglected and underutilized species can play a strategic role in improving many dimensions of livelihoods
Aquatic Macrophyte Diversity and Habitat Characterization of the Cuyahoga River Watershed in Northeastern Ohio
Author Institution: Dept. of Biological, Geological and Environmental Sciences, Cleveland State University, OHWe surveyed aquatic macrophyte diversity and abundance at 20 sites along the main channel of the Cuyahoga River and its tributaries. These sites included 12 sites in the watershed at which an Index of Biological Integrity (IBI) for fish communities deviated significantly from a value predicted by a statistical model of landscape urbanization and stream habitat quality. These sites were classified as Best
of the Best, Worst of the Best, Best of the Worst and Worst of the Worst among 164 sites within the Cuyahoga basin. In order to characterize a site, we collected data on the physical features of the stream and quantified the species abundance of aquatic macrophytes in a 100 m transect. Within each transect, measurements of stream width, bankfull width, stream depth, bankfull depth, and canopy cover were recorded every 10 m. Nitrate, phosphate, and ammonia content of water samples were also assayed. The quality of stream habitat for each site was quantified using the Qualitative Habitat Evaluation Index (QHEI). Strong significant correlations between the measure of stream depth and stream width as well as canopy coverage and bankfull width were observed. A weak significant correlation was found between IBI and QHEI scores. Additional analysis showed that water chemistry did not influence QHEI or IBI scores. An analysis of variance indicated that the IBI scores significantly differed among site types.
Macrophytes were discovered at seven of the 20 sites with an overall richness of 11 species among all sites. The most common aquatic macrophytes were: Elodea canadensis L., Sparganium americanum Nutt., and Sagittaria latifolia Willd. Results demonstrate that physical stream characteristics are strong indicators of fish population integrity, but are not necessarily indicative of aquatic macrophyte
assemblages. Storms severely impacted many streams during the survey, possibly altering macrophyte assemblages. Further surveys should be undertaken at additional sites within the Cuyahoga River watershed for a comprehensive assessment of aquatic macrophytes
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Lunar elemental composition and ivestigations with D-CIXS x-ray mapping spectrometer on SMART-1
The D-CIXS Compact X-ray Spectrometer on ESA SMART-1 successfully launched in Sept 2003 can derive 45 km resolution images of the Moon with a spectral resolution of 185 eV, providing the first high-resolution global map of rock forming element abundances
Measurement of the lifetime of the B_c meson in the semileptonic decay channel
Using approximately 1.3 fb-1 of data collected by the D0 detector between
2002 and 2006, we measure the lifetime of the B_c meson in the B_c -> J/psi mu
nu X final state. A simultaneous unbinned likelihood fit to the J/\psi+mu
invariant mass and lifetime distributions yields a signal of 881 +/- 80 (stat)
candidates and a lifetime measurement of \tau(B_c) = 0.448 +0.038 -0.036 (stat)
+/- 0.032 (syst) ps.Comment: 7 pages, 2 figures, submitted to Phys. Rev. Let
A search for the standard model Higgs boson in the missing energy and acoplanar b-jet topology at sqrt(s) = 1.96 TeV
We report a search for the standard model Higgs boson in the missing energy
and acoplanar b-jet topology, using an integrated luminosity of 0.93 inverse
femtobarn recorded by the D0 detector at the Fermilab Tevatron Collider. The
analysis includes signal contributions from pp->ZH->nu nu b b, as well as from
WH production in which the charged lepton from the W boson decay is undetected.
Neural networks are used to separate signal from background. In the absence of
a signal, we set limits on the cross section of pp->VH times the branching
ratio of H->bb at the 95% C.L. of 2.6 - 2.3 pb, for Higgs boson masses in the
range 105 - 135 GeV, where V=W,Z. The corresponding expected limits range from
2.8 pb - 2.0 pb.Comment: Submitted to Phys. Rev. Letter
Observation of ZZ production in ppbar collisions at sqrt(s) = 1.96 TeV
We present an observation for ZZ -> l+l-l'+l'- (l, l' = e or mu) production
in ppbar collisions at a center-of-mass energy of sqrt(s) = 1.96 TeV. Using 1.7
fb-1 of data collected by the D0 experiment at the Fermilab Tevatron Collider,
we observe three candidate events with an expected background of 0.14 +0.03
-0.02 events. The significance of this observation is 5.3 standard deviations.
The combination of D0 results in this channel, as well as in ZZ -> l+l-nunubar,
yields a significance of 5.7 standard deviations and a combined cross section
of sigma(ZZ) = 1.60 +/- 0.63 (stat.) +0.16 -0.17 (syst.) pb.Comment: 7 pages, 1 figure, 2 tables Modified slightly following review
proces
A novel application of Fiber Bragg Grating (FBG) sensors in MPGD
We present a novel application of Fiber Bragg Grating (FBG) sensors in the
construction and characterisation of Micro Pattern Gaseous Detector (MPGD),
with particular attention to the realisation of the largest triple (Gas
electron Multiplier) GEM chambers so far operated, the GE1/1 chambers of the
CMS experiment at LHC. The GE1/1 CMS project consists of 144 GEM chambers of
about 0.5 m2 active area each, employing three GEM foils per chamber, to be
installed in the forward region of the CMS endcap during the long shutdown of
LHC in 2108-2019. The large active area of each GE1/1 chamber consists of GEM
foils that are mechanically stretched in order to secure their flatness and the
consequent uniform performance of the GE1/1 chamber across its whole active
surface. So far FBGs have been used in high energy physics mainly as high
precision positioning and re-positioning sensors and as low cost, easy to
mount, low space consuming temperature sensors. FBGs are also commonly used for
very precise strain measurements in material studies. In this work we present a
novel use of FBGs as flatness and mechanical tensioning sensors applied to the
wide GEM foils of the GE1/1 chambers. A network of FBG sensors have been used
to determine the optimal mechanical tension applied and to characterise the
mechanical tension that should be applied to the foils. We discuss the results
of the test done on a full-sized GE1/1 final prototype, the studies done to
fully characterise the GEM material, how this information was used to define a
standard assembly procedure and possible future developments.Comment: 4 pages, 4 figures, presented by Luigi Benussi at MPGD 2015 (Trieste,
Italy). arXiv admin note: text overlap with arXiv:1512.0848
Measurement of the electron charge asymmetry in ppbar->W+X->enu+X events at sqrt{s}=1.96 TeV
We present a measurement of the electron charge asymmetry in
ppbar->W+X->enu+X events at a center of mass energy of 1.96 TeV using 0.75 fb-1
of data collected with the D0 detector at the Fermilab Tevatron Collider. The
asymmetry is measured as a function of the electron transverse momentum and
pseudorapidity in the interval (-3.2, 3.2) and is compared with expectations
from next-to-leading order calculations in perturbative quantum chromodynamics.
These measurements will allow more accurate determinations of the proton parton
distribution functions.Comment: 7 pages, 3 figures, Fermilab-Pub-08/249-E, submitted to Phys. Rev.
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