5,815 research outputs found
A long-term perspective on deforestation rates in the Brazilian Amazon
Monitoring tropical forest cover is central to biodiversity preservation, terrestrial carbon stocks, essential ecosystem and climate
functions, and ultimately, sustainable economic development. The Amazon forest is the Earthâs largest rainforest, and despite
intensive studies on current deforestation rates, relatively little is known as to how these compare to historic (pre 1985) deforestation
rates. We quantified land cover change between 1975 and 2014 in the so-called Arc of Deforestation of the Brazilian Amazon,
covering the southern stretch of the Amazon forest and part of the Cerrado biome. We applied a consistent method that made use of
data from Landsat sensors: Multispectral Scanner (MSS), Thematic Mapper (TM), Enhanced Thematic Mapper Plus (ETM+) and
Operational Land Imager (OLI). We acquired suitable images from the US Geological Survey (USGS) for five epochs: 1975, 1990,
2000, 2010, and 2014. We then performed land cover analysis for each epoch using a systematic sample of 156 sites, each one
covering 10 km Ă 10 km, located at the confluence point of integer degree latitudes and longitudes. An object-based classification of
the images was performed with five land cover classes: tree cover, tree cover mosaic, other wooded land, other land cover, and water.
The automatic classification results were corrected by visual interpretation, and, when available, by comparison with higher
resolution imagery. Our results show a decrease of forest cover of 24.2% in the last 40 years in the Brazilian Arc of Deforestation,
with an average yearly net forest cover change rate of -0.71% for the 39 years considered
PACAP-PAC1R modulates fear extinction via the ventromedial hypothalamus
Exposure to traumatic stress can lead to fear dysregulation, which has been associated with posttraumatic stress disorder (PTSD). Previous work showed that a polymorphism in the PACAP-PAC1R (pituitary adenylate cyclase-activating polypeptide) system is associated with PTSD risk in women, and PACAP (ADCYAP1)-PAC1R (ADCYAP1R1) are highly expressed in the hypothalamus. Here, we show that female mice subjected to acute stress immobilization (IMO) have fear extinction impairments related to Adcyap1 and Adcyap1r1 mRNA upregulation in the hypothalamus, PACAP-c-Fos downregulation in the Medial Amygdala (MeA), and PACAP-FosB/ÎFosB upregulation in the Ventromedial Hypothalamus dorsomedial part (VMHdm). DREADD-mediated inhibition of MeA neurons projecting to the VMHdm during IMO rescues both PACAP upregulation in VMHdm and the fear extinction impairment. We also found that women with the risk genotype of ADCYAP1R1 rs2267735 polymorphism have impaired fear extinction
Promoter hypomethylation of the LINE-1 retrotransposable elements activates sense/antisense transcription and marks the progression of chronic myeloid leukemia
Aberrant genome-wide hypomethylation is thought to be
related to tumorigenesis by promoting genomic instability.
Since DNA methylation is considered an important mechanism
for the silencingof retroelements, hypomethylation
in human tumors may lead to their reactivation. However,
the role of DNA hypomethylation in chronic myeloid
leukemia (CML) remains to be elucidated. In this study,
the methylation status of the LINE-1 (L1) retrotransposon
promoter was analysed in CML samples from the chronicphase
(CP, nÂź140) and the blast crisis (BC, nÂź47). L1
hypomethylation was significantly more frequent in BC
(74.5%) than in CP (38%) (Po0.0001). Furthermore,
L1 hypomethylation led to activation of both ORF1 sense
transcription (Po0.0001) and c-MET gene antisense
transcription (Po0.0001), and was significantly associated
with high levels of BCRâABL (PÂź0.02) and
DNMT3b4 (PÂź0.001) transcripts. Interestingly, in
CP-CML, extensive L1 hypomethylation was associated
with poorer prognosis in terms of cytogenetic response
to interferon (PÂź0.004) or imatinib (PÂź0.034) and
progression-free survival (PÂź0.005). The above results
strongly suggest that activation of both sense and
antisense transcriptions by aberrant promoter hypomethylation
of the L1 elements plays a role in the progression
and clinical behavior of the CML
Neutral currents and tests of three-neutrino unitarity in long-baseline experiments
We examine a strategy for using neutral current measurements in long-baseline
neutrino oscillation experiments to put limits on the existence of more than
three light, active neutrinos. We determine the relative contributions of
statistics, cross section uncertainties, event misidentification and other
systematic errors to the overall uncertainty of these measurements. As specific
case studies, we make simulations of beams and detectors that are like the K2K,
T2K, and MINOS experiments. We find that the neutral current cross section
uncertainty and contamination of the neutral current signal by charge current
events allow a sensitivity for determining the presence of sterile neutinos at
the 0.10--0.15 level in probablility.Comment: 24 pages, Latex2e, uses graphicx.sty, 2 postscript figures. Submitted
to the Neutrino Focus Issue of New Journal Physics at http://www.njp.or
Small-Scale Extrusion of Corn Masa By-Products
Corn masa by-product streams are high in fiber and are amenable for utilization in livestock feed rations. This approach is a potentially viable alternative to landfilling, the traditional disposal method for these processing residues. Suspended solids were separated from a masa processing waste stream, blended with soybean meal at four levels (0, 10, 20, and 30% wb), and extruded in a laboratory-scale extruder at speeds of 50 rpm (5.24 rad/sec) and 100 rpm (10.47 rad/sec) with temperature profiles of 80-90-100°C and 100-110-120°C. Processing conditions, including dough and die temperatures, drive torque, specific mechanical energy consumption, product and feed material throughput rates, dough apparent viscosity, and dough density, were monitored during extrusion. The resulting products were subjected to physical and nutritional characterization to determine the effects of processing conditions for these blends. Extrudate analysis included moisture content, water activity, crude protein, in vitro protein digestibility, crude fat, ash, product diameter, expansion ratios, unit and true density, color, water absorption and solubility, and durability. All blends were suitable for extrusion at the processing conditions used. Blend ratio had little effect on either processing parameters or extrudate properties; extrusion temperature and screw speed, on the other hand, significantly affected both processing and product properties
Large enhancement of deuteron polarization with frequency modulated microwaves
We report a large enhancement of 1.7 in deuteron polarization up to values of
0.6 due to frequency modulation of the polarizing microwaves in a two liters
polarized target using the method of dynamic nuclear polarization. This target
was used during a deep inelastic polarized muon-deuteron scattering experiment
at CERN. Measurements of the electron paramagnetic resonance absorption spectra
show that frequency modulation gives rise to additional microwave absorption in
the spectral wings. Although these results are not understood theoretically,
they may provide a useful testing ground for the deeper understanding of
dynamic nuclear polarization.Comment: 10 pages, including the figures coming in uuencoded compressed tar
files in poltar.uu, which also brings cernart.sty and crna12.sty files neede
Spin Structure of the Proton from Polarized Inclusive Deep-Inelastic Muon-Proton Scattering
We have measured the spin-dependent structure function in inclusive
deep-inelastic scattering of polarized muons off polarized protons, in the
kinematic range and . A
next-to-leading order QCD analysis is used to evolve the measured
to a fixed . The first moment of at is .
This result is below the prediction of the Ellis-Jaffe sum rule by more than
two standard deviations. The singlet axial charge is found to be . In the Adler-Bardeen factorization scheme, is
required to bring in agreement with the Quark-Parton Model. A
combined analysis of all available proton and deuteron data confirms the
Bjorken sum rule.Comment: 33 pages, 22 figures, uses ReVTex and smc.sty. submitted to Physical
Review
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A Search for Dark Higgs Bosons
Recent astrophysical and terrestrial experiments have motivated the proposal
of a dark sector with GeV-scale gauge boson force carriers and new Higgs
bosons. We present a search for a dark Higgs boson using 516 fb-1 of data
collected with the BABAR detector. We do not observe a significant signal and
we set 90% confidence level upper limits on the product of the Standard
Model-dark sector mixing angle and the dark sector coupling constant.Comment: 7 pages, 5 postscript figures, published version with improved plots
for b/w printin
Search for New Physics with Jets and Missing Transverse Momentum in pp collisions at sqrt(s) = 7 TeV
A search for new physics is presented based on an event signature of at least
three jets accompanied by large missing transverse momentum, using a data
sample corresponding to an integrated luminosity of 36 inverse picobarns
collected in proton--proton collisions at sqrt(s)=7 TeV with the CMS detector
at the LHC. No excess of events is observed above the expected standard model
backgrounds, which are all estimated from the data. Exclusion limits are
presented for the constrained minimal supersymmetric extension of the standard
model. Cross section limits are also presented using simplified models with new
particles decaying to an undetected particle and one or two jets
Search for the standard model Higgs boson in the H to ZZ to 2l 2nu channel in pp collisions at sqrt(s) = 7 TeV
A search for the standard model Higgs boson in the H to ZZ to 2l 2nu decay
channel, where l = e or mu, in pp collisions at a center-of-mass energy of 7
TeV is presented. The data were collected at the LHC, with the CMS detector,
and correspond to an integrated luminosity of 4.6 inverse femtobarns. No
significant excess is observed above the background expectation, and upper
limits are set on the Higgs boson production cross section. The presence of the
standard model Higgs boson with a mass in the 270-440 GeV range is excluded at
95% confidence level.Comment: Submitted to JHE
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