3,750 research outputs found
Ecological study of aquatic midges and some related insects with special reference to feeding habits
Die Schweiz ist ein reiches Land. Sie verfügt über viele Millionäre. Der große Reichtum konzentriert sich auf wenige Familien und Personen. In der Schweiz leben aber auch eine halbe Million der Bevölkerung (7,5 Mio.) in Haushalten von Erwerbstätigen, die weniger als das Existenzminimum verdienen. Über 200‘000 Personen sind auf Sozialhilfe angewiesen. Bei den Vermögen und den verfügbaren Einkommen hat sich in den letzten Jahren die Kluft zwischen den obersten und untersten zehn Prozent verschärft. Die Zunahme der sozialen Ungleichheit erhöht die soziale Brisanz, was mehr zu ergründen ist. Die soziale Differenzierung dokumentiert Prozesse der Globalisierung. Sie reproduziert und spezifiziert alte soziale Ungleichheiten. Wichtig ist, dass die Soziale Arbeit das thematisiert und weiter theoretisiert
Polyelectrolyte Adsorption
The problem of charged polymer chains (polyelectrolytes) as they adsorb on a
planar surface is addressed theoretically. We review the basic mechanisms and
theory underlying polyelectrolyte adsorption on a single surface in two
situations: adsorption of a single charged chain, and adsorption from a bulk
solution in solvent conditions. The behavior of flexible and
semi-rigid chains is discussed separately and is expressed as function of the
polymer and surface charges, ionic strength of the solution and polymer bulk
concentration. We mainly review mean-field results and briefly comment about
fluctuation effects. The phenomenon of polyelectrolyte adsorption on a planar
surface as presented here is of relevance to the stabilization of colloidal
suspensions. In this respect we also mention calculations of the inter-plate
force between two planar surfaces in presence of polyelectrolyte. Finally, we
comment on the problem of charge overcompensation and its implication to
multi-layers formation of alternating positive and negative polyelectrolytes on
planar surfaces and colloidal particles.Comment: 11 pages, 4 PS figures (Latex/RevTex), submitted to C.R. Acad. Sci
(Paris
On the role of exploitation and exploration strategies in the maintenance of cognitive biases: Beyond the pursuit of instrumental rewards
Why can initial biases persist in repeated choice tasks? Previous research has shown that frequent rewards can lure the decision maker into premature exploitation of a supposedly best option, which can result in the persistence of initial biases. Here, we demonstrate that even in the absence of rewards, initial biases can be perpetuated through a positive testing strategy. After eliciting a biased preference for one of two equally rewarding options, participants (N = 203) could sample freely from both options without the lure of any financial rewards. When participants were told to rule out alternatives in this phase, they explored the supposedly worse option and thereby managed to overcome their initial bias. When told to optimize their strategy, however, they exhibited a positive testing strategy resulting in the continued exploitation of the supposedly better option, a bias they maintained in an incentivized choice phase and later judgments. Across all participants, individual tendencies to exploit one option in earlier phases predicted biased behavior in subsequent phases. The findings highlight that not only the pursuit of instrumental rewards can lead to exploitation and the maintenance of initial biases. We discuss potential consequences for interventions
Разработка способов десульфуризации трансформаторных масел
We report on combined dc and microwave electronic measurements of magnetic flux transport in micron and submicron-patterned high-T-c films. In a given temperature regime below the superconducting transition temperature T-c, the current-driven flux transport is restricted to flux motion guided by the submicron patterns. Via frequency-dependent measurements of the forward transmission coefficient S-21 it is demonstrated that the mechanism of the guided flux transport depends on the microwave frequency and the geometrical size of the superconducting structures. At low frequencies, flux is transported via Abrikosov vortices leading to additional microwave losses. Above a geometrically defined frequency, a different mechanism seems to be responsible for flux transport that does not contribute to the microwave losses and most likely represents a phase-slip type mechanism. The limiting vortex velocity obtained from the frequency dependence of the microwave properties agrees with the Larking-Ovchinnikov critical vortex velocity that is determined via dc pulse measurements. In spite of the change of mechanism, guidance of flux persists in these nanopatterns up to high frequencies of several GHz
Dipolar versus multipolar dynamos: the influence of the background density stratification
Context: dynamo action in giant planets and rapidly rotating stars leads to a
broad variety of magnetic field geometries including small scale multipolar and
large scale dipole-dominated topologies. Previous dynamo models suggest that
solutions become multipolar once inertia becomes influential. Being tailored
for terrestrial planets, most of these models neglected the background density
stratification. Aims: we investigate the influence of the density
stratification on convection-driven dynamo models. Methods: three-dimensional
nonlinear simulations of rapidly rotating spherical shells are employed using
the anelastic approximation to incorporate density stratification. A systematic
parametric study for various density stratifications and Rayleigh numbers
allows to explore the dependence of the magnetic field topology on these
parameters. Results: anelastic dynamo models tend to produce a broad range of
magnetic field geometries that fall on two distinct branches with either strong
dipole-dominated or weak multipolar fields. As long as inertia is weak, both
branches can coexist but the dipolar branch vanishes once inertia becomes
influential. The dipolar branch also vanishes for stronger density
stratifications. The reason is the concentration of the convective columns in a
narrow region close to the outer boundary equator, a configuration that favors
non-axisymmetric solutions. In multipolar solutions, zonal flows can become
significant and participate in the toroidal field generation. Parker dynamo
waves may then play an important role close to onset of dynamo action leading
to a cyclic magnetic field behavior. Conclusion: Our simulations also suggest
that the fact that late M dwarfs have dipolar or multipolar magnetic fields can
be explained in two ways. They may differ either by the relative influence of
inertia or fall into the regime where both types of solutions coexist.Comment: 13 pages, 13 figures, 2 tables, accepted for publication in A&
The histological and immunohistochemical features of the skin lesions in CANDLE syndrome
Chronic atypical neutrophilic dermatosis with lipodystrophy and elevated temperature (CANDLE) syndrome is a newly characterized autoinflammatory disorder, caused by mutations in PSMB8. It is characterized by early-onset fevers, accompanied by a widespread, violaceous and often annular, cutaneous eruption. While the exact pathogenesis of this syndrome is still obscure, it is postulated that the inflammatory disease manifestations stem from excess secretion of interferons. Based on preliminary blood cytokine and gene expression studies, the signature seems to come mostly from type I interferons, which are proposed to lead to the recruitment of immature myeloid cells into the dermis and subcutis. In this study, we systematically analyzed skin biopsies from 6 CANDLE syndrome patients by routine histopathology and immunohistochemistry methods. Skin lesions showed the presence of extensive mixed dermal and subcutaneous inflammatory infiltrate, composed of mononuclear cells, atypical myeloid cells, neutrophils, eosinophils and some mature lymphocytes. Positive LEDER and myeloperoxidase staining supported the presence of myeloid cells. Positive CD68/PMG1 and CD163 staining confirmed the existence of histiocytes and monocytic macrophages in the inflammatory infiltrate. CD123 staining was positive, demonstrating the presence of plasmacytoid dendritic cells. Uncovering the unique histopathologic and immunohistochemical features of CANDLE syndrome provides tools for rapid and specific diagnosis of this disorder as well as further insight into the pathogenesis of this severe, life-threatening conditionThis work was supported in part by the NIAMS Intramural Research Program (IRP) at the National Institutes of Health (NIH); The Authority for Research and Development, Hebrew University of Jerusalem (to A.Z.), and the Young clinician’s grant, Hadassah – Hebrew University Medical Center (to Y.R.
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