986 resultados para Normative theory
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The recently developed semiclassical variational Wigner-Kirkwood (VWK) approach is applied to finite nuclei using external potentials and self-consistent mean fields derived from Skyrme inter-actions and from relativistic mean field theory. VWK consist s of the Thomas-Fermi part plus a pure, perturbative h 2 correction. In external potentials, VWK passes through the average of the quantal values of the accumulated level density and total en energy as a function of the Fermi energy. However, there is a problem of overbinding when the energy per particle is displayed as a function of the particle number. The situation is analyzed comparing spherical and deformed harmonic oscillator potentials. In the self-consistent case, we show for Skyrme forces that VWK binding energies are very close to those obtained from extended Thomas-Fermi functionals of h 4 order, pointing to the rapid convergence of the VWK theory. This satisfying result, however, does not cure the overbinding problem, i.e., the semiclassical energies show more binding than they should. This feature is more pronounced in the case of Skyrme forces than with the relativistic mean field approach. However, even in the latter case the shell correction energy for e.g.208 Pb turns out to be only ∼ −6 MeV what is about a factor two or three off the generally accepted value. As an adhoc remedy, increasing the kinetic energy by 2.5%, leads to shell correction energies well acceptable throughout the periodic table. The general importance of the present studies for other finite Fermi systems, self-bound or in external potentials, is pointed out.
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We perform Hartree calculations of symmetric and asymmetric semi-infinite nuclear matter in the framework of relativistic models based on effective hadronic field theories as recently proposed in the literature. In addition to the conventional cubic and quartic scalar self-interactions, the extended models incorporate a quartic vector self-interaction, scalar-vector non-linearities and tensor couplings of the vector mesons. We investigate the implications of these terms on nuclear surface properties such as the surface energy coefficient, surface thickness, surface stiffness coefficient, neutron skin thickness and the spin-orbit force.
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By means of computer simulations and solution of the equations of the mode coupling theory (MCT),we investigate the role of the intramolecular barriers on several dynamic aspects of nonentangled polymers. The investigated dynamic range extends from the caging regime characteristic of glass-formers to the relaxation of the chain Rouse modes. We review our recent work on this question,provide new results, and critically discuss the limitations of the theory. Solutions of the MCT for the structural relaxation reproduce qualitative trends of simulations for weak and moderate barriers. However, a progressive discrepancy is revealed as the limit of stiff chains is approached. This dis-agreement does not seem related with dynamic heterogeneities, which indeed are not enhanced by increasing barrier strength. It is not connected either with the breakdown of the convolution approximation for three-point static correlations, which retains its validity for stiff chains. These findings suggest the need of an improvement of the MCT equations for polymer melts. Concerning the relaxation of the chain degrees of freedom, MCT provides a microscopic basis for time scales from chain reorientation down to the caging regime. It rationalizes, from first principles, the observed deviations from the Rouse model on increasing the barrier strength. These include anomalous scaling of relaxation times, long-time plateaux, and nonmonotonous wavelength dependence of the mode correlators.
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The article presents a discussion of foundational issues in the field of management science, focusing on advances in management theory and research. The metaphor of explanatory lenses is used as a rubric to illustrate the theoretical challenges involved in elucidating the interrelationships of various factors in organizational behavior. The importance of clarifying such interrelationships is emphasized, from the standpoint of editing scholarly papers on such topics for publication. Topics discussed include communication and psychology in management, economics, and behavioral finance.
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We present computer simulations of a simple bead-spring model for polymer melts with intramolecular barriers. By systematically tuning the strength of the barriers, we investigate their role on the glass transition. Dynamic observables are analyzed within the framework of the mode coupling theory (MCT). Critical nonergodicity parameters, critical temperatures, and dynamic exponents are obtained from consistent fits of simulation data to MCT asymptotic laws. The so-obtained MCT λ-exponent increases from standard values for fully flexible chains to values close to the upper limit for stiff chains. In analogy with systems exhibiting higher-order MCT transitions, we suggest that the observed large λ-values arise form the interplay between two distinct mechanisms for dynamic arrest: general packing effects and polymer-specific intramolecular barriers. We compare simulation results with numerical solutions of the MCT equations for polymer systems, within the polymer reference interaction site model (PRISM) for static correlations. We verify that the approximations introduced by the PRISM are fulfilled by simulations, with the same quality for all the range of investigated barrier strength. The numerical solutions reproduce the qualitative trends of simulations for the dependence of the nonergodicity parameters and critical temperatures on the barrier strength. In particular, the increase in the barrier strength at fixed density increases the localization length and the critical temperature. However the qualitative agreement between theory and simulation breaks in the limit of stiff chains. We discuss the possible origin of this feature.
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Formation of nanosized droplets/bubbles from a metastable bulk phase is connected to many unresolved scientific questions. We analyze the properties and stability of multicomponent droplets and bubbles in the canonical ensemble, and compare with single-component systems. The bubbles/droplets are described on the mesoscopic level by square gradient theory. Furthermore, we compare the results to a capillary model which gives a macroscopic description. Remarkably, the solutions of the square gradient model, representing bubbles and droplets, are accurately reproduced by the capillary model except in the vicinity of the spinodals. The solutions of the square gradient model form closed loops, which shows the inherent symmetry and connected nature of bubbles and droplets. A thermodynamic stability analysis is carried out, where the second variation of the square gradient description is compared to the eigenvalues of the Hessian matrix in the capillary description. The analysis shows that it is impossible to stabilize arbitrarily small bubbles or droplets in closed systems and gives insight into metastable regions close to the minimum bubble/droplet radii. Despite the large difference in complexity, the square gradient and the capillary model predict the same finite threshold sizes and very similar stability limits for bubbles and droplets, both for single-component and two-component systems.
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Epäasianmukaisella verontorjunnalla kannustintyyppisten ympäristöverojen yhteydessä tarkoitetaan sitä, että veron määrä vähenee ilman ympäristön tilan paranemista. Tutkimuksessa selvitetään, millaisia epäasianmukaisia verontorjuntakeinoja ympäristöveroihin liittyy, kuinka paljon niissä on kyse lainsäädäntöteknisistä valinnoista sekä lainsäädännön puutteellisuudesta ja kuinka ympäristöverotusta voitaisiin mahdollisesti parantaa. Esitys painottuu normatiiviseen sääntelyteoriaan eli siihen, minkälainen ohjauskeino tai sääntely palvelee parhaiten tietyn yhteiskuntapoliittisen päämäärän saavuttamista. Päästöt ovat usein suorassa suhteessa tuotteen ominaisuuksiin, mutta ympäristöverot eivät. Ongelmalliseksi muodostuvat lisäksi veronalennukset, kuten veroporrastukset ja veron palautukset. Nämä kannustavat epäasianmukaiseen verontorjuntaan, kuten yritysjärjestelyihin, hamstraukseen ja esimerkiksi jätteiden sijoittamiseen kaatopaikkojen ulkopuolelle. Epäasianmukaista verontorjuntaa voidaan ehkäistä muun muassa kiristämällä rangaistuksia, tiedottamalla, kaventamalla normaaliverokohtelun ja lievennetyn verokohtelun eroa sekä verotuksen kohdetta muuttamalla. Tärkeintä tulevaisuudessa olisi kuitenkin keskittyä kansainväliseen yhteistyöhön ja ympäristöverotuksen yhdenmukaistamiseen.
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Tutkielman tavoitteena on selvittää, miten markkinointiviestintä voidaan investointihyödykemarkkinoilla toteuttaa asiakaslähtöisesti. Siinä on käsitelty asiakkaiden tarpeita markkinoinnin lähtökohtana, kohderyhmän segmentointia sekä viestinnän sisällön rakentamista investointihyödyke-markkinoilla. Tutkimuksessa on käytetty normatiivista eli soveltavaa case-tutkimusta ja sen analyysimenetelmä on ollut kvalitatiivinen. Tutkielma jakautuu teoreettiseen ja empiiriseen osaan: tutkimuksen teoriaosa on toteutettu kirjallisuustutkimuksena ja empiirisen osan pohjana on käytetty aiheesta aiemmin tehtyä kvantitatiivista tutkimusta, jota on täydennetty kvalitatiivisilla syvähaastatteluilla. Empiirisen osan tavoitteena on rakentaa markkinointiviestinnän sanoma OptiDwell-kalanterille sen kohderyhmän tarpeiden selvityksen pohjalta.
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Tutkielman tavoitteena on markkinointisuunnitelman laatiminen teollisuustuotteelle, jota business-to-business -markkinoilla toimiva case-yritys valmistaa. Aihetta tarkastellaan ensin teoreettisesti lähdekirjallisuuden avulla ja sen jälkeen empiirisesti case-yrityksen näkökulmasta. Tutkimusmenetelmänä on normatiivinen eli soveltava case-tutkimus. Tutkimusote on kvalitatiivinen. Markkinointisuunnitelma laaditaan analysoimalla yrityksen ulkoista ja sisäistä toimintaympäristöä, asettamalla markkinoinnin tavoitteet, määrittelemällä markkinointistrategiat ja yksilöimällä toimintaohjeet. Markkinointisuunnitelman laatiminen kannattaa, sillä se tehostaa yrityksen ulkoista markkinointia. Tutkielman tuloksena voidaan todeta, että case-yrityksellä on hyvät mahdollisuudet menestyä hihnavaakamarkkinoilla uudella tuotteellaan, kunhan se saa nimeään tunnetuksi.
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This study views personnel strategy process in strategic management perspective. The theoretical part discusses about personnel management theories and the theory of strategy process. After that the empirical part combines both theories mentioned above into a normative approach of personnel strategy process.
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We analyze the results for infinite nuclear and neutron matter using the standard relativistic mean field model and its recent effective field theory motivated generalization. For the first time, we show quantitatively that the inclusion in the effective theory of vector meson self-interactions and scalar-vector cross-interactions explains naturally the recent experimental observations of the softness of the nuclear equation of state, without losing the advantages of the standard relativistic model for finite nuclei.
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BACKGROUND: Theory of mind (ToM), the capacity to infer the intention, beliefs and emotional states of others, is frequently impaired in behavioural variant fronto-temporal dementia patients (bv-FTDp); however, its impact on caregiver burden is unexplored. SETTING: National Institute of Neurological Disorders and Stroke, National Institutes of Health. SUBJECTS: bv-FTDp (n = 28), a subgroup of their caregivers (n = 20) and healthy controls (n = 32). METHODS: we applied a faux-pas (FP) task as a ToM measure in bv-FTDp and healthy controls and the Zarit Burden Interview as a measure of burden in patients' caregivers. Patients underwent structural MRI; we used voxel-based morphometry to examine relationships between regional atrophy and ToM impairment and caregiver burden. RESULTS: FP task performance was impaired in bv-FTDp and negatively associated with caregiver burden. Atrophy was found in areas involved in ToM. Caregiver burden increased with greater atrophy in left lateral premotor cortex, a region associated in animal models with the presence of mirror neurons, possibly involved in empathy. CONCLUSION: ToM impairment in bv-FTDp is associated with increased caregiver burden.