1,339 research outputs found
The Effects of Frustration and Social Desirability on Heterosexual Attraction
Walster, Walster, Piliavin and Schmidt\u27s (1973) finding that a selectively hard-to-get female was preferred over either an easy-to-get or a hard-to-get female was replicated for unfrustrated males. However, when males were mildly frustrated, they preferred females who had indicated attraction toward them. The implications of these results were discussed in terms of external rewards and the motivational state of individuals
Use of Combined Systemic Hypothermia and Local Heat Treatment to Enhance Temperature Differences Between Tumor and Normal Tissues
The feasibility of combining local heat treatment with wholebody hypothermia in an effort to improve therapeutic gain was assessed. Superficial, non perfused phantom tumors were fashioned in eight anesthetized mongrel dogs by transplantation of the spleen from the abdomen to a subcutaneous site on the hind limb. After pretreatment of the animal with the vasodilator hydralazine (0.5 mg/kg, IV) to enhance normal tissue perfusion, the spleen implant was heated with a 2450-MHz microwave diathermy apparatus, first with the animal\u27s core body temperature in the normal range (39°C) and then after the animal had been packed in ice to reduce core temperature to 30°C. Applied power density and temperatures in both the phantom tumor and underlying muscle tissue were recorded during brief interruptions of diathermy until steady-state temperatures had been achieved. Under normothermic conditions with time-averaged applied power of 0.038 W/ml to phantom tumor and 0.014 W/ml to underlying muscle, tumor temperature rose to 45.9 ± l.8°C, while muscle temperature remained at 40.5 ± 0.7°C. During whole-body hypothermia applied power could be increased to 0.114 W/ml in phantom tumor and to 0.025 W/ml in muscle. Muscle temperature rose only to 33.8 ± l.6°C, while that of the nonperfused phantom tumor rose to 53.6 ± 4.3°C with systemic hypothermia. These results are in agreement with predictions based on the bioheat transfer equation, i.e., heat extraction from well-perfused normal tissues is greatly augmented by cooling of the arterial blood, allowing greater power input to the tumor-bearing region, higher tumor temperatures, and enhanced therapeutic gain during local heat treatments of poorly perfused tumor nodules
Supernova Remnants in the Fossil Starburst in M82
We report the discovery of ten compact H-alpha-bright sources in the
post-starburst region northeast of the center of M82, ``M82 B.'' These objects
have H alpha luminosities and sizes consistent with Type II supernova remnants
(SNRs). They fall on the same H alpha surface brightness-diameter (Sigma-D)
relation defined by SNRs in other nearby star-forming galaxies, with the M82
candidates lying preferentially at the small diameter end. These are the first
candidates for optically-visible SNRs in M82 outside the heavily obscured
central starburst within ~250 pc from the galactic center. If these sources are
SNRs, they set an upper limit to the end of the starburst in region ``B2,''
about 500 pc from the galaxy's core, of ~50 Myr. Region ``B1,'' about 1000 pc
from the core, lacks good SNR candidates and is evidently somewhat older. This
suggests star formation in the galaxy has propagated inward toward the
present-day intense starburst core.Comment: Re-submitted to AJ, referee's comments taken into account, 15 pages
LaTeX preprint style, 4 postscript figures; full-resolution figures available
from http://www.astro.virginia.edu/~rd7a/snrs/ Changes: minor textual changes
and orientation/axes of Fig.
Polar motion and UT1: Comparison of VLBI, lunar laser, satellite laser, satellite Doppler, and conventional astrometric determinations
Very long baseline interferometry observations made with a 3900 km baseline interferometer (Haystack Observatory in Massachusetts to Owens Valley Observation in California) were used to estimate changes in the X-component of the position of the Earth's pole and in UT1. These estimates are compared with corresponding ones from lunar laser ranging, satellite laser ranging, satellite Doppler, and stellar observations
Assessing Gale Crater as an Exploration Zone for the First Human Mission to Mars
Mars is the "horizon goal" for human space flight [1]. Towards that endeavor, one must consider several factors in regards to choosing a landing site suitable for a human-rated mission including: entry, descent, and landing (EDL) characteristics, scientific diversity, and possible insitu resources [2]. Selecting any one place is a careful balance of reducing risks and increasing scientific return for the mission
DPRESS: Localizing estimates of predictive uncertainty
<p>Abstract</p> <p>Background</p> <p>The need to have a quantitative estimate of the uncertainty of prediction for QSAR models is steadily increasing, in part because such predictions are being widely distributed as tabulated values disconnected from the models used to generate them. Classical statistical theory assumes that the error in the population being modeled is independent and identically distributed (IID), but this is often not actually the case. Such inhomogeneous error (heteroskedasticity) can be addressed by providing an individualized estimate of predictive uncertainty for each particular new object <it>u</it>: the standard error of prediction <it>s</it><sub>u </sub>can be estimated as the non-cross-validated error <it>s</it><sub>t* </sub>for the closest object <it>t</it>* in the training set adjusted for its separation <it>d </it>from <it>u </it>in the descriptor space relative to the size of the training set.</p> <p><display-formula><graphic file="1758-2946-1-11-i1.gif"/></display-formula></p> <p>The predictive uncertainty factor <it>γ</it><sub>t* </sub>is obtained by distributing the internal predictive error sum of squares across objects in the training set based on the distances between them, hence the acronym: <it>D</it>istributed <it>PR</it>edictive <it>E</it>rror <it>S</it>um of <it>S</it>quares (DPRESS). Note that <it>s</it><sub>t* </sub>and <it>γ</it><sub>t*</sub>are characteristic of each training set compound contributing to the model of interest.</p> <p>Results</p> <p>The method was applied to partial least-squares models built using 2D (molecular hologram) or 3D (molecular field) descriptors applied to mid-sized training sets (<it>N </it>= 75) drawn from a large (<it>N </it>= 304), well-characterized pool of cyclooxygenase inhibitors. The observed variation in predictive error for the external 229 compound test sets was compared with the uncertainty estimates from DPRESS. Good qualitative and quantitative agreement was seen between the distributions of predictive error observed and those predicted using DPRESS. Inclusion of the distance-dependent term was essential to getting good agreement between the estimated uncertainties and the observed distributions of predictive error. The uncertainty estimates derived by DPRESS were conservative even when the training set was biased, but not excessively so.</p> <p>Conclusion</p> <p>DPRESS is a straightforward and powerful way to reliably estimate individual predictive uncertainties for compounds outside the training set based on their distance to the training set and the internal predictive uncertainty associated with its nearest neighbor in that set. It represents a sample-based, <it>a posteriori </it>approach to defining applicability domains in terms of localized uncertainty.</p
Iron-Manganese Redox Reactions in Endeavour Crater Rim Apron Rocks
The Mars Exploration Rover Opportunity has been exploring Noachian age rocks and outcrops on the rim of the 22 km diameter Endeavour crater since August 2011. The Cape York area is a low-lying rim of Endeavour that contains 3 distinct lithologies: 1) the stratigraphically lowest Matijevic fm of pre-impact lithology, 2) Shoemaker fm of impact breccias, and 3) the stratigraphically highest rim lithology Grasberg fm of post-impact sediments that drape the lower slopes of the rim. The sulfate-rich sediment of the Burns fm lies unconformably over the Grasberg fm. Ca-sulfate veins were discovered in Grasberg fm sediments; the sulfates precipitated from aqueous fluids flowing upward through these materials. Opportunity investigated the chemistry and morphology of outcrops in the Matijevic fm that have Fe(sup 3+)-rich smectite detected by orbital signatures returned by CRISM on MRO. Matijevic fm also contains "boxwork" fractures with chemistry consistent with an Al-rich smectite and veins that appear to be rich in Ca-sulfate. More recently on Cape Tribulation, Opportunity has characterized two S-, Mg- and Mn-rich rich rocks overturned and fractured by the rover's wheels on Cook Haven. Those rocks have been dubbed "Pinnacle Island" and "Stuart Island" and will be referred to as the "Island" rocks. The objectives of this study are to characterize the Fe and Mn contents in the Cape York materials, including the two Island rocks, and to provide a model for Mn mobilization and precipitation. Detailed geochemistry of Endeavour rim rocks is presented in a companion paper. Geochemical trends and elemental associations were obtained from data returned by the Alpha Particle X-ray Spectrometer (APXS) on Opportunity
Oxidation Of Manganese At Kimberley, Gale Crater: More Free Oxygen In Mars' Past?
High Mn concentrations provide unique indicators of water-rich environments and their redox state. Very high-potential oxidants are required to oxidize Mn to insoluble, high-valence oxides that can precipitate and concentrate Mn in rocks and sediments; these redox potentials are much higher than those needed to oxidize Fe or S. Consequently, Mn-rich rocks on Earth closely track the rise of atmospheric oxygen. Given the association between Mn-rich rocks and the redox state of surface environments, observations of anomalous Mn enrichments on Mars raise similar questions about redox history, solubility and aqueous transport, and availability as a metabolic substrate. Our observations suggest that at least some of the high Mn present in Gale crater occurs in the form of Mn-oxides filling veins that crosscut sand-stones, requiring post-depositional precipitation as highly oxidizing fluids moved through the fractured strata after their deposition and lithification
Overview of the Spirit Mars Exploration Rover Mission to Gusev Crater: Landing Site to Backstay Rock in the Columbia Hills
Spirit landed on the floor of Gusev Crater and conducted initial operations on soil covered, rock-strewn cratered plains underlain by olivine-bearing basalts. Plains surface rocks are covered by wind-blown dust and show evidence for surface enrichment of soluble species as vein and void-filling materials and coatings. The surface enrichment is the result of a minor amount of transport and deposition by aqueous processes. Layered granular deposits were discovered in the Columbia Hills, with outcrops that tend to dip conformably with the topography. The granular rocks are interpreted to be volcanic ash and/or impact ejecta deposits that have been modified by aqueous fluids during and/or after emplacement. Soils consist of basaltic deposits that are weakly cohesive, relatively poorly sorted, and covered by a veneer of wind blown dust. The soils have been homogenized by wind transport over at least the several kilometer length scale traversed by the rover. Mobilization of soluble species has occurred within at least two soil deposits examined. The presence of mono-layers of coarse sand on wind-blown bedforms, together with even spacing of granule-sized surface clasts, suggest that some of the soil surfaces encountered by Spirit have not been modified by wind for some time. On the other hand, dust deposits on the surface and rover deck have changed during the course of the mission. Detection of dust devils, monitoring of the dust opacity and lower boundary layer, and coordinated experiments with orbiters provided new insights into atmosphere-surface dynamics
Quasi-long-range order in the random anisotropy Heisenberg model: functional renormalization group in 4-\epsilon dimensions
The large distance behaviors of the random field and random anisotropy O(N)
models are studied with the functional renormalization group in 4-\epsilon
dimensions. The random anisotropy Heisenberg (N=3) model is found to have a
phase with the infinite correlation radius at low temperatures and weak
disorder. The correlation function of the magnetization obeys a power law <
m(x) m(y) >\sim |x-y|^{-0.62\epsilon}. The magnetic susceptibility diverges at
low fields as \chi \sim H^{-1+0.15\epsilon}. In the random field O(N) model the
correlation radius is found to be finite at the arbitrarily weak disorder for
any N>3. The random field case is studied with a new simple method, based on a
rigorous inequality. This approach allows one to avoid the integration of the
functional renormalization group equations.Comment: 12 pages, RevTeX; a minor change in the list of reference
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