2,911 research outputs found
Sum frequency generation from partially ordered media and interfaces: a polarization analysis
Is Agricultural Intensification Profitable For Mozambican Smallholders? An Appraisal of the Inputs Subsector and the 1996/97 DNER/Sg2000 Program
Farm Management, Downloads July 2008-June 2009: 5,
Wolves: Behavior, Ecology, and Conservation: Photo Section I
Wolves in Yellowstone National Park\u27s restored population often must compete with grizzly bears at the carcasses of their kills. Especially after their first feeding at a kill, wolves tend to relinquish their kills to bears. Photograph by Doug Smith.
Elk are one of the most common prey of wolves in the northern Rocky Mountains of North America, primarily because in most areas they tend to outnumber other prey. This large bull standing his ground escaped this pack. Photograph by Doug Smith
What Makes Agricultural Intensification Profitable for Mozambican Smallholders? An Appraisal of the Inputs Subsector and the 1996/97 DNER/SG2000 Program
This report summarizes an appraisal of input utilization and marketing in Mozambique, focusing on the following research questions: (1) What are current smallholder yields for major commodities, and what is the potential for increasing yields through the use of improved technologies? (2) To what extent are improved technologies already being used by smallholders, and is the use of improved technologies profitable? (3) How are improved seeds, fertilizer and pesticides currently produced and distributed? and (4) What are the key constraints and opportunities for increasing the use of improved technologies by smallholders?food security, food policy, improved technologies, Farm Management, Downloads July 2008-July 2009: 9, O31,
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Individual Differences in Dopamine Are Associated with Reward Discounting in Clinical Groups But Not in Healthy Adults.
Some people are more willing to make immediate, risky, or costly reward-focused choices than others, which has been hypothesized to be associated with individual differences in dopamine (DA) function. In two studies using PET imaging, one empirical (Study 1: N = 144 males and females across 3 samples) and one meta-analytic (Study 2: N = 307 across 12 samples), we sought to characterize associations between individual differences in DA and time, probability, and physical effort discounting in human adults. Study 1 demonstrated that individual differences in DA D2-like receptors were not associated with time or probability discounting of monetary rewards in healthy humans, and associations with physical effort discounting were inconsistent across adults of different ages. Meta-analytic results for temporal discounting corroborated our empirical finding for minimal effect of DA measures on discounting in healthy individuals but suggested that associations between individual differences in DA and reward discounting depend on clinical features. Addictions were characterized by negative correlations between DA and discounting, but other clinical conditions, such as Parkinson's disease, obesity, and attention-deficit/hyperactivity disorder, were characterized by positive correlations between DA and discounting. Together, the results suggest that trait differences in discounting in healthy adults do not appear to be strongly associated with individual differences in D2-like receptors. The difference in meta-analytic correlation effects between healthy controls and individuals with psychopathology suggests that individual difference findings related to DA and reward discounting in clinical samples may not be reliably generalized to healthy controls, and vice versa.SIGNIFICANCE STATEMENT Decisions to forgo large rewards for smaller ones due to increasing time delays, uncertainty, or physical effort have been linked to differences in dopamine (DA) function, which is disrupted in some forms of psychopathology. It remains unclear whether alterations in DA function associated with psychopathology also extend to explaining associations between DA function and decision making in healthy individuals. We show that individual differences in DA D2 receptor availability are not consistently related to monetary discounting of time, probability, or physical effort in healthy individuals across a broad age range. By contrast, we suggest that psychopathology accounts for observed inconsistencies in the relationship between measures of DA function and reward discounting behavior
Gaps and weaknesses in the global protected area network for safeguarding at-risk species
Protected areas are essential to biodiversity conservation. Creating new parks can protect larger populations and more species, yet strengthening existing parks, particularly those vulnerable to harmful human activities, is a critical but underappreciated step for safeguarding at-risk species. Here, we model the area of habitat that terrestrial mammals, amphibians, and birds have within park networks and their vulnerability to current downgrading, downsizing, or degazettement events and future land-use change. We find that roughly 70% of species analyzed have scant representation in parks, or occur within parks that are affected by shifts in formal legal protections or are vulnerable to increased human pressures. Our results also show that expanding and strengthening park networks across just 1% of the world’s land area could preserve irreplaceable habitats of 1191 species that are particularly vulnerable to extinction
What Makes Agricultural Intensification Profitable for Mozambican Smallholders? An Appraisal of the Inputs Subsector and the 1996/97 DNER/SG2000 Program, Volume II: Main Report
Ministry of Agriculture and Rural Development, Directorate of Economics, Republic of Mozambiquefood security, food policy, Mozambique, agriculture, Farm Management, Q18,
Systematic study of X-ray Cavities in the brightest galaxy of the Draco Constellation NGC 6338
We present results based on the systematic analysis of currently available
Chandra archive data on the brightest galaxy in the Draco constellation NGC
6338, in order to investigate the properties of the X-ray cavities. In the
central ~6 kpc, at least a two and possibly three, X-ray cavities are evident.
All these cavities are roughly of ellipsoidal shapes and show a decrement in
the surface brightness of several tens of percent. In addition to these
cavities, a set of X-ray bright filaments are also noticed which are spatially
coincident with the H{\alpha} filaments over an extent of 15 kpc. The H{\alpha}
emission line filaments are perpendicular to the X- ray cavities. Spectroscopic
analysis of the hot gas in the filaments and cavities reveal that the X-ray
filaments are cooler than the gas contained in the cavities. The emission line
ratios and the extended, asymmetric nature of the H{\alpha} emission line
filaments seen in this system require a harder ionizing source than that
produced by star formation and/or young, massive stars. Radio emission maps
derived from the analysis of 1.4 GHz VLA FIRST survey data failed to show any
association of these X-ray cavities with radio jets, however, the cavities are
filled by radio emission. The total power of the cavities is 17\times 1042 erg
s-1 and the ratio of the radio luminosity to cavity power is ~ 10-4, implying
that most of the jet power is mechanical.Comment: The paper contains 12 figures and 3 tables, Accepted 2011 December 7
for publication in MNRA
Surface Characterization of Polycarbonate Parts from Selective Laser Sintering
Surfaces of polycarbonate Selective Laser Sintering parts are investigated to determine the
characteristics affecting part quality. Surfaces are obtained from experiments by varying
four factors, namely, layer thickness, laser power, part orientation, and build angle. First,
spatial modes on SLS surfaces are decomposed using a qualitative spectral analysis in an
attempt to find their origins. Thermal modes on the top surfaces of polycarbonate SLS
parts result in the other modes being obscured; melting and part curl are concluded to be
the dominant modes on these surfaces. Furthermore, surface modes resulting from building
the part at an angle to the powder bed are identified and modeled. Then, mathematical
measures are computed for the surfaces to determine surface precision quantitatively. An
analysis-of-variance study is performed to reveal the trends in surface precision with respect
to control factors. Surface precision is shown to change significantly with laser power and
part orientation, and trade-offs with part strength are presented.Mechanical Engineerin
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