12,080 research outputs found

    The Impact of Residential Treatment on Emotionally Disturbed Boys

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    Within the past four decades, social work has witnessed the development of increasingly specialized servicecs to children, among these a sort of “total impact therapy” generally defined as residential treatment. In conjunction with the basic social work values of the bio-psycho-social nature of human maladjustment, residential centres have attempted to help the child effect a happier adjustment to his life situation by meeting some ungratified basic need. Institutions for dependent children complimented those for custodial care of even isolation; contemporary residential treatment centres are designed to meet a broader range of needs of the child than those of forty years ago through a variety of approaches, often referred to as milieu therapy. Consideration of the common needs of children is basic to questions concerning the place of institutional treatment and the particular type of child for which this social work service is the most appropriate one. The residential treatment centre addresses the whole gamut of a child’s needs from physical care to rehabilitation. Exposure to, and participation in, a group life experience simulating as closely as possible the family or community life experience is the element differentiating residential care from other treatment modes. By involvement in the realities of his daily situation and the working through or resolution of these, the child is helped to cope with his own growth and development—physical, emotional, and social. Problems and questions examined in this paper revolve around the residential treatment centre defined vaguely by the Child Welfare League of America as “A building....maintained and operated by a chartered agency, organization or institution, whose main purpose is to provide shelter and care to a group of unrelated children and youths up to eighteen years of age.” More specifically, the concern for research, the proposal and plans for implementation are focused on Mount St. Joseph, an autonomous, non-profit institution providing care for boys with moderate to severe emotional disturbances

    Masses of light tetraquarks and scalar mesons in the relativistic quark model

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    Masses of the ground state light tetraquarks are dynamically calculated in the framework of the relativistic diquark-antidiquark picture. The internal structure of the diquark is taken into account by calculating the form factor of the diquark-gluon interaction in terms of the overlap integral of the diquark wave functions. It is found that scalar mesons with masses below 1 GeV: f_0(600) (\sigma), K^*_0(800) (\kappa), f_0(980) and a_0(980) agree well with the light tetraquark interpretation.Comment: 9 pages, Report-no adde

    Magnetically Controlled Spasmodic Accretion During Star Formation. II. Results

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    The problem of the late accretion phase of the evolution of an axisymmetric, isothermal magnetic disk surrounding a forming star has been formulated in a companion paper. The "central sink approximation" is used to circumvent the problem of describing the evolution inside the opaque central region for densities greater than 10^11 cm^-3 and radii smaller than a few AUs. Only the electrons are assumed to be attached to the magnetic field lines, and the effects of both negatively and positively charged grains are accounted for. After a mass of 0.1 solar mass accumulates in the central cell (forming star), a series of magnetically driven outflows and associated outward propagating shocks form in a quasi-periodic fashion. As a result, mass accretion onto the protostar occurs in magnetically controlled bursts. We refer to this process as spasmodic accretion. The shocks propagate outward with supermagnetosonic speeds. The period of dissipation and revival of the outflow decreases in time, as the mass accumulated in the central sink increases. We evaluate the contribution of ambipolar diffusion to the resolution of the magnetic flux problem of star formation during the accretion phase, and we find it to be very significant although not sufficient to resolve the entire problem yet. Ohmic dissipation is completely negligible in the disk during this phase of the evolution. The protostellar disk is found to be stable against interchange-like instabilities, despite the fact that the mass-to-flux ratio has temporary local maxima.Comment: Astrophysical Journal, in press. 29 pages, 13 figure

    Responses of a bacterial pathogen to phosphorus limitation of its aquatic invertebrate host

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    Host nutrition is thought to affect the establishment, persistence, and severity of pathogenic infections. Nutrient-deficient foods possibly benefit pathogens by constraining host immune function or benefit hosts by limiting parasite growth and reproduction. However, the effects of poor elemental food quality on a host's susceptibility to infection and disease have received little study. Here we show that the bacterial microparasite Pasteuria ramosa is affected by the elemental nutrition of its aquatic invertebrate host, Daphnia magna. We found that high food carbon : phosphorus (C: P) ratios significantly reduced infection rates of Pasteuria in Daphnia and led to lower within-host pathogen multiplication. In addition, greater virulent effects of bacterial infection on host reproduction were found in Daphnia-consuming P-deficient food. Poor Daphnia elemental nutrition thus reduced the growth and reproduction of its bacterial parasite, Pasteuria. The effects of poor host nutrition on the pathogen were further evidenced by Pasteuria's greater inhibition of reproduction in P-limited Daphnia. Our results provide strong evidence that elemental food quality can significantly influence the incidence and intensity of infectious disease in invertebrate hosts

    Gravitational catalysis of chiral and color symmetry breaking of quark matter in hyperbolic space

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    We study the dynamical breaking of chiral and color symmetries of dense quark matter in the ultrastatic hyperbolic spacetime RH3R\otimes H^3 in the framework of an extended Nambu--Jona-Lasinio model. On the basis of analytical expressions for chiral and color condensates as functions of curvature and temperature, the phenomenon of dimensional reduction and gravitational catalysis of symmetry breaking in strong gravitational field is demonstrated in the regime of weak coupling constants. In the case of strong couplings it is shown that curvature leads to small corrections to the flat-space values of condensate and thus enhances the symmetry breaking effects. Finally, using numerical calculations phase transitions under the influence of chemical potential and negative curvature are considered and the phase portrait of the system is constructed.Comment: 14 pages, 5 figure

    Off-shell pion electromagnetic form factor from a gauge-invariant Nambu-Jona-Lasinio model

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    The off--shell electromagnetic vertex function of pions and kaons is studied in a bosonized Nambu--Jona-Lasinio model with a gauge--invariant proper--time cutoff. The slope of the pion form factor with respect to the pion 4--momentum is found to be equal to the on--shell pion charge radius in the chiral limit. The off--shell slope of the K0K^0 form factor is zero, that of the K±K^\pm about 15\% smaller than that of the pion. We compare our results with those of a recent calculation in chiral perturbation theory.Comment: (9 p., standard LaTeX, 1 PostScript figure appended) UNITUE-THEP-7/9

    Color superconductivity in the static Einstein Universe

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    We study the behavior of quark and diquark condensates in dense quark matter under the influence of a gravitational field adopting as a simple model the static DD-dimensional Einstein Universe. Calculations are performed in the framework of the extended Nambu--Jona-Lasinio model at finite temperature and quark density on the basis of the thermodynamic potential and the gap equations. Quark and diquark condensates as functions of the chemical potential and temperature at different values of the curvature have been studied. Phase portraits of the system have been constructed

    A diquark model for baryons containing one heavy quark

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    We present a phenomenological ansatz for coupling a heavy quark with two light quarks to form a heavy baryon. The heavy quark is treated in the heavy mass limit, and the light quark dynamics is approximated by propagating scalar and axial vector 'diquarks'. The resulting effective lagrangian, which incorporates heavy quark and chiral symmetry, describes interactions of heavy baryons with Goldstone bosons in the low energy region. As an application, the Isgur--Wise form factors are estimated.Comment: 9 pages + 8 figures, both as uuencoded PS, discussion of Bjorken limit (1 par + 1 fig) added, to appear in Z.Phys.

    Streamers in air splitting into three branches

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    We investigate the branching of positive streamers in air and present the first systematic investigation of splitting into more than two branches. We study discharges in 100 mbar artificial air that is exposed to voltage pulses of 10 kV applied to a needle electrode 160 mm above a grounded plate. By imaging the discharge with two cameras from three angles, we establish that about every 200th branching event is a branching into three. Branching into three occurs more frequently for the relatively thicker streamers. In fact, we find that the surface of the total streamer cross-sections before and after a branching event is roughly the same.Comment: 6 pages, 7 figure

    Symmetric Versus Nonsymmetric Structure of the Phosphorus Vacancy on InP(110)

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    The atomic and electronic structure of positively charged P vacancies on InP(110) surfaces is determined by combining scanning tunneling microscopy, photoelectron spectroscopy, and density-functional theory calculations. The vacancy exhibits a nonsymmetric rebonded atomic configuration with a charge transfer level 0.75+-0.1 eV above the valence band maximum. The scanning tunneling microscopy (STM) images show only a time average of two degenerate geometries, due to a thermal flip motion between the mirror configurations. This leads to an apparently symmetric STM image, although the ground state atomic structure is nonsymmetric.Comment: 5 pages including 3 figures. related publications can be found at http://www.fhi-berlin.mpg.de/th/paper.htm
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