140 research outputs found
Systems, interactions and macrotheory
A significant proportion of early HCI research was guided by one very clear vision: that the existing theory base in psychology and cognitive science could be developed to yield engineering tools for use in the interdisciplinary context of HCI design. While interface technologies and heuristic methods for behavioral evaluation have rapidly advanced in both capability and breadth of application, progress toward deeper theory has been modest, and some now believe it to be unnecessary. A case is presented for developing new forms of theory, based around generic “systems of interactors.” An overlapping, layered structure of macro- and microtheories could then serve an explanatory role, and could also bind together contributions from the different disciplines. Novel routes to formalizing and applying such theories provide a host of interesting and tractable problems for future basic research in HCI
Pressure and linear heat capacity in the superconducting state of thoriated UBe13
Even well below Tc, the heavy-fermion superconductor (U,Th)Be13 has a large
linear term in its specific heat. We show that under uniaxial pressure, the
linear heat capacity increases in magnitude by more than a factor of two. The
change is reversible and suggests that the linear term is an intrinsic property
of the material. In addition, we find no evidence of hysteresis or of latent
heat in the low-temperature and low-pressure portion of the phase diagram,
showing that all transitions in this region are second order.Comment: 5 pages, 4 figure
Quantum deformation of the angular distributions of synchrotron radiation. Emission of particles in the first excited state
The exact expressions for the characteristics of synchrotron radiation of
charged particles in the first excited state are obtained in analytical form
using quantum theory methods. We performed a detailed analysis of the angular
distribution structure of radiation power and its polarization for particles
with spin 0 and 1/2. It is shown that the exact quantum calculations lead to
results that differ substantially from the predictions of classical theory
Modification of Experimental Protocols for a Space Shuttle Flight and Applications for the Analysis of Cytoskeletal Structures During Fertilization, Cell Division , and Development in Sea Urchin Embryos
To explore the role of microgravity on cytoskeletal organization and skeletal calcium deposition during fertilization, cell division, and early development, the sea urchin was chosen as a model developmental system. Methods were developed to employ light, immunofluorescence, and electron microscopy on cultures being prepared for flight on the Space Shuttle. For analysis of microfilaments, microtubules, centrosomes, and calcium-requiring events, our standard laboratory protocols had to be modified substantially for experimentation on the Space Shuttle. All manipulations were carried out in a closed culture chamber containing 35 ml artificial sea water as a culture fluid. Unfertilized eggs stored for 24 hours in these chambers were fertilized with sperm diluted in sea water and fixed with concentrated fixatives for final fixation in formaldehyde, taxol, EGTA, and MgCl2(exp -6)H2O for 1 cell to 16 cell stages to preserve cytoskeletal structures for simultaneous analysis with light, immunofluorescence, and electron microscopy, and 1.5 percent glutaraldehyde and 0.4 percent formaldehyde for blastula and plueus stages. The fixed samples wre maintained in chambers without degradation for up to two weeks after which the specimens were processed and analyzed with routine methods. Since complex manipulations are not possible in the closed chambers, the fertilization coat was removed from fixation using 0.5 percent freshly prepared sodium thioglycolate solution at pH 10.0 which provided reliable immunofluorescence staining for microtubules. Sperm/egg fusion, mitosis, cytokinesis, and calcium deposition during spicule formatin in early embryogenesis were found to be without artificial alterations when compared to cells fixed fresh and processed with conventional methods
The Opportunity Cost of the Conservation Reserve Program: A Kansas Land Example
The effects of the Conservation Reserve Program (CRP) on farmland values is investigated using a set of parcel-level data for land sales in Kansas over the period 1998 to 2014. The sales data are used to estimate a hedonic model of land values that allows for the opportunity cost of CRP enrollment to vary across space and time. Factors impacting the opportunity costs include the relative productivity of land, returns to farming, and the time remaining under the CRP contracts. We find that the discount associated with having land under CRP contract averages 7%
Eletrolite leakage as a technique to diagnose euphorbia heterophylla biotypes resistant to ppo-inhibitors herbicides
How To Find Charm in Nuclear Collisions at RHIC and LHC
Measurements of dilepton production from charm decay and Drell-Yan processes
respectively probe the gluon and sea quark distributions in hadronic
collisions. In nucleus-nucleus collisions, these hard scattering processes
constitute a `background' to thermal contributions from the hot matter produced
by the collision. To determine the magnitude and behavior of this background,
we calculate the hard scattering contribution to dilepton production in nuclear
collisions at RHIC and LHC at next to leading order in perturbative QCD.
Invariant mass, rapidity and transverse momentum distributions are presented.
We compare these results to optimistic hydrodynamic estimates of the thermal
dilepton production. We find that charm production from hard scattering is by
far the dominant contribution. Experiments therefore can measure the gluon
distribution in the nuclear target and projectile and, consequently, can
provide new information on gluon shadowing. We then illustrate how experimental
cuts on the rapidity gap between the leptons can aid in reducing the charm
background, thereby enhancing thermal information.Comment: 32 pages, latex, 19 figure
Influência do envelhecimento acelerado na anatomia da testa de sementes de soja, cv. Monsoy 8400
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