273 research outputs found

    Micro-level opportunity structures as determinants of non-CEO executive pay

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    We develop a theory wherein the pay of non-CEO executives can be explained by micro-level opportunity structures--the intersection of functional position, CEO background, human capital, and firm strategic resource allocation decisions. Our theory suggests a positive association between pay and a position made visible by resource allocation decisions, a functional background similar to that of the CEO, and a position that helps the firm manage strategic resource allocations. A unique longitudinal data set that combines survey and archival data on the four highest echelons of senior executives in large U.S. firms provided support for this multilevel framework

    Supramolecular interactions in clusters of polar and polarizable molecules

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    We present a model for molecular materials made up of polar and polarizable molecular units. A simple two state model is adopted for each molecular site and only classical intermolecular interactions are accounted for, neglecting any intermolecular overlap. The complex and interesting physics driven by interactions among polar and polarizable molecules becomes fairly transparent in the adopted model. Collective effects are recognized in the large variation of the molecular polarity with supramolecular interactions, and cooperative behavior shows up with the appearance, in attractive lattices, of discontinuous charge crossovers. The mean-field approximation proves fairly accurate in the description of the gs properties of MM, including static linear and non-linear optical susceptibilities, apart from the region in the close proximity of the discontinuous charge crossover. Sizeable deviations from the excitonic description are recognized both in the excitation spectrum and in linear and non-linear optical responses. New and interesting phenomena are recognized near the discontinuous charge crossover for non-centrosymmetric clusters, where the primary photoexcitation event corresponds to a multielectron transfer.Comment: 14 pages, including 11 figure

    Two genes required for diabetes in BB rats: Evidence from cyclical intercrosses and backcrosses

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    The BB rat strain spontanteously develops diabetes mellitus which rapidly progresses to ketoacidosis and death if not treated with exogenous insulin. 40-60% of BB rats develop overt diabetes and exhibit prominent insulitis, selective pancreatic beta cell destruction, and circulating antibodies to islet cell surfaces. Diabetes can be prevented with multiple forms of immunotherapy and can be transferred with activated splenic iymphocytes. In addition to the diabetic syndrome, BB rats have a striking lymphophenia characterized by an almost total lack of circulating T cells. Colle et al., using a sequential breeding program, have described associations between the development of diabetes and the inheritance of major histocompatibility complex (MHC) 1 genes, lymphopenia, and susceptibility to pancreatic lymphocytic infiltrates

    Anthropogenic Space Weather

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    Anthropogenic effects on the space environment started in the late 19th century and reached their peak in the 1960s when high-altitude nuclear explosions were carried out by the USA and the Soviet Union. These explosions created artificial radiation belts near Earth that resulted in major damages to several satellites. Another, unexpected impact of the high-altitude nuclear tests was the electromagnetic pulse (EMP) that can have devastating effects over a large geographic area (as large as the continental United States). Other anthropogenic impacts on the space environment include chemical release ex- periments, high-frequency wave heating of the ionosphere and the interaction of VLF waves with the radiation belts. This paper reviews the fundamental physical process behind these phenomena and discusses the observations of their impacts.Comment: 71 pages, 35 figure

    New neutron-rich nuclei Zr103,104 and the A100 region of deformation

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    Partial decay schemes in the neutron-rich nuclei Zr103 and Zr104 have been measured for the first time and rotational bands in Zr100 102 have been extended to spins of up to 10Latin small letter h with stroke by observing prompt rays from the spontaneous fisson of Cm248. These nuclei are among the most deformed known at low spin and excitation energy. The level structures in the odd-A nuclei show that the h11/2 intruder orbital plays an important role in stabilizing the deformation in this region

    Can forest management based on natural disturbances maintain ecological resilience?

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    Given the increasingly global stresses on forests, many ecologists argue that managers must maintain ecological resilience: the capacity of ecosystems to absorb disturbances without undergoing fundamental change. In this review we ask: Can the emerging paradigm of natural-disturbance-based management (NDBM) maintain ecological resilience in managed forests? Applying resilience theory requires careful articulation of the ecosystem state under consideration, the disturbances and stresses that affect the persistence of possible alternative states, and the spatial and temporal scales of management relevance. Implementing NDBM while maintaining resilience means recognizing that (i) biodiversity is important for long-term ecosystem persistence, (ii) natural disturbances play a critical role as a generator of structural and compositional heterogeneity at multiple scales, and (iii) traditional management tends to produce forests more homogeneous than those disturbed naturally and increases the likelihood of unexpected catastrophic change by constraining variation of key environmental processes. NDBM may maintain resilience if silvicultural strategies retain the structures and processes that perpetuate desired states while reducing those that enhance resilience of undesirable states. Such strategies require an understanding of harvesting impacts on slow ecosystem processes, such as seed-bank or nutrient dynamics, which in the long term can lead to ecological surprises by altering the forest's capacity to reorganize after disturbance

    High-spin transition quadrupole moments in neutron-rich Mo and Ru nuclei: Testing Îł softness?

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    The transition quadrupole moments, Qt, of rotational bands in the neutron-rich, even-mass 102-108Mo and 108-112Ru nuclei were measured in the 8-16 â„Ź spin range with the Doppler-shift attenuation method. The nuclei were populated as fission fragments from 252Cf fission. The detector setup consisted of the Gammasphere spectrometer and the HERCULES fast-plastic array. At moderate spin, the Qt moments are found to be reduced with respect to the values near the ground states. Attempts to describe the observations in mean-field-based models, specifically cranked relativistic Hartree-Bogoliubov theory, illustrate the challenge theory faces and the difficulty to infer information on Îł softness and triaxiality from the data

    Accretion, Outflows, and Winds of Magnetized Stars

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    Many types of stars have strong magnetic fields that can dynamically influence the flow of circumstellar matter. In stars with accretion disks, the stellar magnetic field can truncate the inner disk and determine the paths that matter can take to flow onto the star. These paths are different in stars with different magnetospheres and periods of rotation. External field lines of the magnetosphere may inflate and produce favorable conditions for outflows from the disk-magnetosphere boundary. Outflows can be particularly strong in the propeller regime, wherein a star rotates more rapidly than the inner disk. Outflows may also form at the disk-magnetosphere boundary of slowly rotating stars, if the magnetosphere is compressed by the accreting matter. In isolated, strongly magnetized stars, the magnetic field can influence formation and/or propagation of stellar wind outflows. Winds from low-mass, solar-type stars may be either thermally or magnetically driven, while winds from massive, luminous O and B type stars are radiatively driven. In all of these cases, the magnetic field influences matter flow from the stars and determines many observational properties. In this chapter we review recent studies of accretion, outflows, and winds of magnetized stars with a focus on three main topics: (1) accretion onto magnetized stars; (2) outflows from the disk-magnetosphere boundary; and (3) winds from isolated massive magnetized stars. We show results obtained from global magnetohydrodynamic simulations and, in a number of cases compare global simulations with observations.Comment: 60 pages, 44 figure

    Ação de fitoreguladores no desenvolvimento de Chrysanthemum leucanthemum L.

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    Plants of Chrysanthemum leucanthemum grown in pots with soil under greenhouse conditions, were sprayed with growth regulators twice, in May and June, to study the development of the plants in October. Succinic acid-2,2-dimethylhydrazide (SADH) at concentrations of 1250, 2500 and 5000 ppm, (2-chloroethyl) trimethylammonium chloride (CCC) 2000 ppm, (2-chloroethyl) phosphonic acid (CEPA) 320 ppm, maleic hydrazide (MH;) 1000 ppm, gibberellic acid (GA) 50 and 100 ppm, indolylacetic acid (IAA) 100 ppm, and water as check treatment, were applied. MH 1000 ppm reduced the number of leaves and stems. SADH treatments reduced the shoot growth and the number of stems. Applications of IAA 100 ppm promoted the formation of higher number of leaves and stems in Chrysanthemum leucanthemum. It was seen that sprays with GA at a concentration of 100 ppm elongated shoots.Plantas ornamentais de Chrysanthemum leucanthemum, cultivadas em recipientes contendo solo como substrato, em condições de estufa, foram pulverizadas em maio e junho com reguladores de crescimento, com a finalidade de se verificar a ação dos mesmos no desenvolvimento das plantas, determinado em outubro. Aplicaram-se SADH nas concentrações de 1250, 2500 e 5000 ppm, CCC na dosagem de 2000 ppm, CEPA 320 ppm, MH 1000 ppm, GA 50 e 100 ppm, IAA 100 ppm e água como controle. Hidrazida maleica 1000 ppm reduziu o número de folhas e hastes formadas. Tratamentos com ácido succínico - 2,2-dimetilhidrazida diminuiram a altura do caule e o número de hastes das plantas. Aplicações de ácido indolilacético 100 ppm promoveram a formação de maior número de folhas e de hastes em Chrysanthemum. Pulverizações com ácido giberélico 100 ppm incrementaram a altura do caule da espécie estudada

    Characterization of octupole-type structures in Th 221

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    A detailed level scheme for Th221 has been established in an experiment using the O18+207Pb reaction at 96 MeV. The evaporation residues from this fissile system were selected with the HERCULES detector array and residue-gated Îł rays were measured with Gammasphere. Three band structures of interlinked, alternating-parity levels are observed, two of which are non-yrast. In addition, several high-lying excitations are found. The yrast band is seen up to spin-parity 37/2- and 39/2+, beyond which a high-spin feeding transition is observed. The non-yrast sequences are interpreted as parity-doublet structures, based on a configuration similar to that of the yrast band in Th223 (K=5/2). The key properties of even-odd nuclei in this mass region [B(E1)/B(E2) and B(M1)/B(E2) ratios, spin alignments, parity splittings] are reviewed
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