774 research outputs found

    Magnetic and axial vector form factors as probes of orbital angular momentum in the proton

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    We have recently examined the static properties of the baryon octet (magnetic moments and axial vector coupling constants) in a generalized quark model in which the angular momentum of a polarized nucleon is partly spin ⟨Sz⟩\langle S_z \rangle and partly orbital ⟨Lz⟩\langle L_z \rangle. The orbital momentum was represented by the rotation of a flux-tube connecting the three constituent quarks. The best fit is obtained with ⟨Sz⟩=0.08±0.15\langle S_z \rangle = 0.08\pm 0.15, ⟨Lz⟩=0.42±0.14\langle L_z \rangle = 0.42\pm 0.14. We now consider the consequences of this idea for the q2q^2-dependence of the magnetic and axial vector form factors. It is found that the isovector magnetic form factor GMisovec(q2)G_M^{\mathrm{isovec}}(q^2) differs in shape from the axial form factor FA(q2)F_A(q^2) by an amount that depends on the spatial distribution of orbital angular momentum. The model of a rigidly rotating flux-tube leads to a relation between the magnetic, axial vector and matter radii, ⟨r2⟩mag=fspin⟨r2⟩axial+52forb⟨r2⟩matt\langle r^2 \rangle_{\mathrm{mag}} = f_{\mathrm{spin}} \langle r^2 \rangle_{\mathrm{axial}} + \frac{5}{2} f_{\mathrm{orb}} \langle r^2 \rangle_{\mathrm{matt}}, where forb/fspin=13⟨Lz⟩/GAf_{\mathrm{orb}}/ f_{\mathrm{spin}} = \frac{1}{3}\langle L_z \rangle / G_A, fspin+forb=1f_{\mathrm{spin}} + f_{\mathrm{orb}} = 1. The shape of FA(q2)F_A(q^2) is found to be close to a dipole with MA=0.92±0.06M_A = 0.92\pm 0.06 GeV.Comment: 18 pages, 5 ps-figures, uses RevTe

    Bank business model migrations in Europe: determinants and effects

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    In response to post-crisis regulatory reforms, the European banking sector has undergone significant changes that have led banks to reconsider their strategies, structures and operations. Based on a sample of over 3,000 banks from 32 European countries during the period 2010–2017, we identify banks’ business models based on cluster analysis and track their evolution.We then apply a logistic regression and find that banks with higher risk and lower profitability are more likely to change their business model. Employing a propensity score matching approach, we investigate the effect of migration on bank performance and find that changing the business model affects banks positively (i.e. migrating banks increase their profitability, stability and cost efficiency). The effect of migration differs depending on the target business model. When switches are a consequence of being acquired or motivated by regulatory compliance, the positive impact remains

    The role of organizational citizenship behavior and gender between job satisfaction and task performance

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    Job satisfaction (JS) is an indicator of individual psychosocial health. Consistent evidence showed that voluntary extra-role behavior in organizations, namely organizational citizenship behavior (OCB), can also contribute to individual psychological health. JS has been found to positively influence employees’ OCB, and both JS and OCB have been found to predict employees’ task performance (TP). The purpose of this study was to investigate whether employees’ OCB mediates the relationship of JS with TP, taking into consideration gender as a potential moderator, and other sociodemographic and work-related characteristics as confounding variables. A total of 518 employees, 54.6% women, aged 19–66 years with a mean age of about 36 years, completed measures of JS, OCB, and TP. Results showed a partial mediation of OCB in the JS-TP relationship, which was invariant across gender. A potential practical implication of findings is that human resource managers and practitioners might ultimately benefit male and female employees’ well-being as well as the organizations’ productivity by developing targeted individual-and group-level trainings and interventions to enhance JS and OCB

    The historical development of pharmacopoeias and the inclusion of exotic herbal drugs with a focus on Europe and Brazil

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    Ethnopharmacological relevance: In spite of the rich bio-cultural diversity found in the Neotropics relatively few herbal drugs native to South America are included in the global pharmacopoeia. Material and methods: In the attempt to historically explain the inclusion of herbal drugs into official pharmacopoeias we consider the disparate epidemiology and cultural evolution of the New and the Old World. We then trace the development of pharmacopoeias and review forces that worked towards and against the synchronization of pharmacopoeias and highlight the role of early chemical and pharmacological studies in Europe. Finally, we compare the share of exotic and native herbal drug species included in the Brazilian Pharmacopoeia with the share of exotic and native species included in the European Pharmacopoeia as well as those used for products registered with ANVISA. Results: The domination of Eurasian herbal drugs in the European Pharmacopoeia seems to be conditioned by the geographical extension of Eurasia, which facilitated the interchange of materia medica and the creation of a consensus of use since ancient times. At the time of the Conquest the epidemiology of the Amerindian populations resembled that of pre-agriculturalist societies while no written consensus around efficacious medicine existed. Subsequently, introduced and well-tried plant species of the Old World gained therapeutic importance in the New World. Conclusion: The research focus in Europe and the US resulted in a persistence of herbal drugs with a historic importance in the European and US pharmacopoeias, which gained a status as safe and efficacious. During the last decades only few ethnopharmacological field-studies have been conducted with indigenous Amerindian groups living in the Brazilian Amazon, which might be attributable to difficulties in obtaining research permissions. Newly adopted regulations regarding access to biodiversity and traditional knowledge as well as the simplified procedure for licencing herbal medicinal products in Brazil prospects an interesting future for those aiming at developing herbal medicine based on bio-cultural diversity and respecting the protocols regulating benefit sharing

    Formation mechanisms and phase stability of solid-state grown cspbi3 perovskites

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    CsPbI3 inorganic perovskite is synthesized by a solvent-free, solid-state reaction, and its structural and optical properties can be deeply investigated using a multi-technique approach. X-ray Diffraction (XRD) and Raman measurements, optical absorption, steady-time and time-resolved luminescence, as well as High-Resolution Transmission Electron Microscopy (HRTEM) imaging, were exploited to understand phase evolution as a function of synthesis time length. Nanoparticles with multiple, well-defined crystalline domains of different crystalline phases were observed, usually surrounded by a thin, amorphous/out-of-axis shell. By increasing the synthesis time length, in addition to the pure α phase, which was rapidly converted into the δ phase at room temperature, a secondary phase, Cs4PbI6, was observed, together with the 715 nm-emitting γ phase

    A Fully Differential Digital CMOS Pulse UWB Generator

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    A new fully-digital CMOS pulse generator for impulse-radio Ultra-Wide-Band (UWB) systems is presented. First, the shape of the pulse which best fits the FCC regulation in the 3.1-5 GHz sub-band of the entire 3.1-10.6 GHz UWB bandwidth is derived and approximated using rectangular digital pulses. In particular, the number and width of pulses that approximate an ideal template is found through an ad-hoc optimization methodology. Then a fully differential digital CMOS circuit that synthesizes the pulse sequence is conceived and its functionality demonstrated through post-layout simulations. The results show a very good agreement with the FCC requirements and a low power consumptio

    Power-Gating Technique for Network-on-Chip Buffers

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    A new approach to reducing leakage power in network-on-chip buffers is presented. The non-uniformity of buffer utilisation is leveraged across the network and power-gating is applied to scarcely utilised buffers. Instead of turning-off the buffers completely, a buffer portion is kept turned-on. This design choice has a significant performance benefit because the buffer is always able to receive network packets. Design aspects and trade-offs in a 45 nm CMOS technology are discussed and results obtained over video application benchmarks are presented. It is shown that it is possible to reduce buffer leakage by 40% without performance penalt
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