15,501 research outputs found
ILR Impact Brief - It’s a Paradox: Union Workers Less Satisfied but Less Likely to Quit
[Excerpt] Existing economic models of human behavior do not adequately deal with the seeming inconsistency between union members’ attitudes about their jobs and their subsequent actions. A more promising explanation might derive from job satisfaction theory, which suggests that union members have a particular set of values, expectations, and frames of reference that they use to evaluate the outcomes of their work effort. Individuals who join unions may place higher value on wages and benefits, which are the focus of most collectively- bargained contracts, than do non-union workers; historically, unions have delivered in this regard. Unionized workers may be more dissatisfied because of a more adversarial climate (e.g., testy supervisory and interpersonal relations, narrowly-defined jobs) but are less likely to quit because the things they value most—good wages and benefits—are provided
Experimental studies of perceptual processes, section two Progress report, Jan. - Sep. 30, 1965
Complex discriminative behavior, fixed ratio reinforcement of large units of behavior and deferred reinforcement studied in chimpanzee
Organs from animals for man
In the following review some of the problems of xenotransplantation shall be discussed, based on the few experimental data available so far and on reports in the literature describing investigations which may be of importance for xenotransplantation. The impact of gravity on the upright posture of man versus almost all other mammals, the dysfunction between enzymes and hormones in different species and the lack of interactions between interleukins, cytokines and vasoactive substances will be taken into consideration. The question must be asked whether different levels of carrier molecules or serum proteins play a role in the physiological network. Even though the development of transgenic animals or other imaginative manipulations may lead to the acceptance of any type of xenografted organ, it has to be established for how long the products of the xenografts are able to act in the multifactorial orchestra. We are far from understanding xenogeneic molecular mechanisms involved in toxicity, necrosis and apoptosis or even reperfusion injury and ischemia in addition to the immediate mechanisms of the hyperacute xenogeneic rejection. Here, cell adhesion, blood clotting and vasomotion collide and bring micro-and macrocirculation to a standstill. All types of xenogeneic immunological mechanisms studied so far were found to have a more serious impact than those seen in allogeneic transplantation. In addition we are now only beginning to understand that so-called immunological parameters in allogeneic mechanisms act also in a true physiological manner in the xenogeneic situation. These molecular mechanisms occur behind the curtain of hyperacute, accelerated, acute or chronic xenograft rejection of which only some folds have been lifted to allow glimpses of part of the total scene. Other obstacles are likely to arise when long-term survival is achieved. These obstacles include retroviral infections, transfer of prions and severe side effects of the massive immunosuppression which will be needed. Moral, ethical and religious concerns are under debate and the species-specific production of proteins of the foreign donor species developed for clinical use suddenly appears to be a greater problem than anticipated
Effective field theory description of halo nuclei
Nuclear halos emerge as new degrees of freedom near the neutron and proton
driplines. They consist of a core and one or a few nucleons which spend most of
their time in the classically-forbidden region outside the range of the
interaction. Individual nucleons inside the core are thus unresolved in the
halo configuration, and the low-energy effective interactions are short-range
forces between the core and the valence nucleons. Similar phenomena occur in
clusters of He atoms, cold atomic gases near a Feshbach resonance, and some
exotic hadrons. In these weakly-bound quantum systems universal scaling laws
for s-wave binding emerge that are independent of the details of the
interaction. Effective field theory (EFT) exposes these correlations and
permits the calculation of non-universal corrections to them due to
short-distance effects, as well as the extension of these ideas to systems
involving the Coulomb interaction and/or binding in higher angular-momentum
channels. Halo nuclei exhibit all these features. Halo EFT, the EFT for halo
nuclei, has been used to compute the properties of single-neutron, two-neutron,
and single-proton halos of s-wave and p-wave type. This review summarizes these
results for halo binding energies, radii, Coulomb dissociation, and radiative
capture, as well as the connection of these properties to scattering
parameters, thereby elucidating the universal correlations between all these
observables. We also discuss how Halo EFT's encoding of the long-distance
physics of halo nuclei can be used to check and extend ab initio calculations
that include detailed modeling of their short-distance dynamics.Comment: 104 pages, 31 figures. Topical Review for Journal of Physics G. v2
incorporates several modifications, particularly to the Introduction, in
response to referee reports. It also corrects multiple typos in the original
submission. It corresponds to the published versio
Simulating the impact of the Smith Cloud
We investigate the future evolution of the Smith Cloud by performing
hydrodynamical simulations of the cloud impact onto the gaseous Milky Way
Galactic disk. We assume a local origin for the cloud and thus do not include a
dark matter component to stabilize it. Our main focus is the cloud's influence
on the local and global star formation rate (SFR) of the Galaxy and whether or
not it leads to an observable event in the far future. Our model assumes two
extremes for the mass of the Smith Cloud, an upper mass limit of 10
M and a lower mass limit of 10 M, compared to the
observational value of a few 10 M. In addition, we also make the
conservative assumption that the entirety of the cloud mass of the extended
Smith Cloud is concentrated within the tip of the cloud. We find that the
impact of the low-mass cloud produces no noticeable change in neither the
global SFR nor the local SFR at the cloud impact site within the galactic disk.
For the high-mass cloud we find a short-term (roughly 5 Myr) increase of the
global SFR of up to 1 M yr, which nearly doubles the normal
Milky Way SFR. This highly localized starburst should be observable.Comment: 14 pages, 5 figure
Efimov universality with Coulomb interaction
The universal properties of charged particles are modified by the presence of
a long-range Coulomb interaction. We investigate the modification of Efimov
universality as a function of the Coulomb strength using the Gaussian expansion
method. The resonant short-range interaction is described by Gaussian
potentials to which a Coulomb potential is added. We calculate binding energies
and root mean square radii for the three- and four-body systems of charged
particles and present our results in a generalised Efimov plot. We find that
universal features can still be discerned for weak Coulomb interaction, but
break down for strong Coulomb interaction. The root-mean-square radius plateaus
at increasingly smaller values for strong Coulomb interaction and the
probablity distributions of the states become more concentrated inside the
Coulomb barrier. As an example, we apply our universal model to nuclei with an
alpha-cluster substructure. Our results point to strong non-universal
contributions in that sector.Comment: 18 pages, 9 figures, final version (with small orthographical
corrections
Universal few-body physics in a harmonic trap
Few-body systems with resonant short-range interactions display universal
properties that do not depend on the details of their structure or their
interactions at short distances. In the three-body system, these properties
include the existence of a geometric spectrum of three-body Efimov states and a
discrete scaling symmetry. Similar universal properties appear in 4-body and
possibly higher-body systems as well. We set up an effective theory for
few-body systems in a harmonic trap and study the modification of universal
physics for 3- and 4-particle systems in external confinement. In particular,
we focus on systems where the Efimov effect can occur and investigate the
dependence of the 4-body spectrum on the experimental tuning parameters.Comment: 20 pages, 10 figures, final version, new references adde
Universal physics of bound states of a few charged particles
We study few-body bound states of charged particles subject to attractive
zero-range/short-range plus repulsive Coulomb interparticle forces. The
characteristic length scales of the system at zero energy are set by the
Coulomb length scale and the Coulomb-modified effective range
. We study shallow bound states of charged particles with
and show that these systems obey universal scaling laws
different from neutral particles. An accurate description of these states
requires both the Coulomb-modified scattering length and the effective range
unless the Coulomb interaction is very weak (). Our findings are
relevant for bound states whose spatial extent is significantly larger than the
range of the attractive potential. These states enjoy universality -- their
character is independent of the shape of the short-range potential.Comment: 8 pages, 6 figures, extended discussion, results unchanged, to appear
in Phys. Lett.
Star formation rates of distant luminous infrared galaxies derived from Halpha and IR luminosities
We present a study of the star formation rate (SFR) for a sample of 16
distant galaxies detected by ISOCAM at 15um in the CFRS0300+00 and CFRS1400+52
fields. Their high quality and intermediate resolution VLT/FORS spectra have
allowed a proper correction of the Balmer emission lines from the underlying
absorption. Extinction estimates using the Hbeta/Hgamma and the Halpha/Hbeta
Balmer decrement are in excellent agreement, providing a robust measurement of
the instantaneous SFR based on the extinction-corrected Halpha luminosity. Star
formation has also been estimated exploiting the correlations between IR
luminosity and those at MIR and radio wavelengths. Our study shows that the
relationship between the two SFR estimates follow two distinct regimes: (1) for
galaxies with SFRIR below ~ 100Msolar/yr, the SFR deduced from Halpha
measurements is a good approximation of the global SFR and (2) for galaxies
near of ULIRGs regime, corrected Halpha SFR understimated the SFR by a factor
of 1.5 to 2. Our analyses suggest that heavily extincted regions completely
hidden in optical bands (such as those found in Arp 220) contribute to less
than 20% of the global budget of star formation history up to z=1.Comment: (1) GEPI, Obs. Meudon, France ;(2) CEA-Saclay, France ;(3) ESO,
Gemany ;(4) IAC, Spain. To appear in A&
The Coronal Analysis of SHocks and Waves (CASHeW) Framework
Coronal Bright Fronts (CBF) are large-scale wavelike disturbances in the
solar corona, related to solar eruptions. They are observed in extreme
ultraviolet (EUV) light as transient bright fronts of finite width, propagating
away from the eruption source. Recent studies of individual solar eruptive
events have used EUV observations of CBFs and metric radio type II burst
observations to show the intimate connection between low coronal waves and
coronal mass ejection (CME)-driven shocks. EUV imaging with the Atmospheric
Imaging Assembly(AIA) instrument on the Solar Dynamics Observatory (SDO) has
proven particularly useful for detecting CBFs, which, combined with radio and
in situ observations, holds great promise for early CME-driven shock
characterization capability. This characterization can further be automated,
and related to models of particle acceleration to produce estimates of particle
fluxes in the corona and in the near Earth environment early in events. We
present a framework for the Coronal Analysis of SHocks and Waves (CASHeW). It
combines analysis of NASA Heliophysics System Observatory data products and
relevant data-driven models, into an automated system for the characterization
of off-limb coronal waves and shocks and the evaluation of their capability to
accelerate solar energetic particles (SEPs). The system utilizes EUV
observations and models written in the Interactive Data Language (IDL). In
addition, it leverages analysis tools from the SolarSoft package of libraries,
as well as third party libraries. We have tested the CASHeW framework on a
representative list of coronal bright front events. Here we present its
features, as well as initial results. With this framework, we hope to
contribute to the overall understanding of coronal shock waves, their
importance for energetic particle acceleration, as well as to the better
ability to forecast SEP events fluxes.Comment: Accepted for publication in the Journal of Space Weather and Space
Climate (SWSC
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