121,522 research outputs found

    Soft Gluon Logarithmic Resummation and Hadron Mass Effects in Single Hadron Inclusive Production

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    We define a general scheme for the evolution of fragmentation functions which resums soft gluon logarithms in a manner consistent with fixed order evolution. We present an explicit example of our approach in which double logarithms are resummed using the Double Logarithmic Approximation. We show that this scheme reproduces the Modified Leading Logarithm Approximation in certain limits, and find that after using it to fit quark and gluon fragmentation functions to experimental data,a good description of the data from the largest x values to the peak region in ln (1/x) is obtained. In addition, we develop a treatment of hadron mass effects which gives additional improvements at small x.Comment: Prepared for Ringberg Workshop: New Trends in HERA Physics 2005, October 2 - 7, 200

    Distribution of melanopsin positive neurons in pigmented and albino mice: evidence for melanopsin interneurons in the mouse retina.

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    Here we have studied the population of intrinsically photosensitive retinal ganglion cells (ipRGCs) in adult pigmented and albino mice. Our data show that although pigmented (C57Bl/6) and albino (Swiss) mice have a similar total number of ipRGCs, their distribution is slightly different: while in pigmented mice ipRGCs are more abundant in the temporal retina, in albinos the ipRGCs are more abundant in superior retina. In both strains, ipRGCs are located in the retinal periphery, in the areas of lower Brn3a(+)RGC density. Both strains also contain displaced ipRGCs (d-ipRGCs) in the inner nuclear layer (INL) that account for 14% of total ipRGCs in pigmented mice and 5% in albinos. Tracing from both superior colliculli shows that 98% (pigmented) and 97% (albino) of the total ipRGCs, become retrogradely labeled, while double immunodetection of melanopsin and Brn3a confirms that few ipRGCs express this transcription factor in mice. Rather surprisingly, application of a retrograde tracer to the optic nerve (ON) labels all ipRGCs, except for a sub-population of the d-ipRGCs (14% in pigmented and 28% in albino, respectively) and melanopsin positive cells residing in the ciliary marginal zone (CMZ) of the retina. In the CMZ, between 20% (pigmented) and 24% (albino) of the melanopsin positive cells are unlabeled by the tracer and we suggest that this may be because they fail to send an axon into the ON. As such, this study provides the first evidence for a population of melanopsin interneurons in the mammalian retina

    Analgesic and Hepatoprotective Activity of Methanolic Leaf Extract of Ocimum gratissimum (L.).

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    The methanolic extract of Ocimum gratissimum (L.) leaves was screened for analgesic and hepatoprotective activity in albino rats, respectively. The use of the hot-plate method to study central analgesic activity of the leaves extract in albino rats indicated that the extract possesses the ability to significantly reduce pain threshold and also increase the response latency period to thermal stimuli in albino rats, similar to the reference drug acetylsalicylic acid. After treatment reaction time of albino rats was significantly increased to 10.92 sec with 40 mg kg-1 of leaves extract, whereas acetylsalicylic acid also increased reaction time to 12.53 sec with 25 mL kg-1. A decline in the reaction time beyond 1.61 sec was observed by the reference drug and leaves extract. Albino rats whose livers were damaged with a hepatotoxin-Carbon tetrachloride (CCl4) 0.5 mL kg-1 i.p. were used to test for hepatoprotective properties of the plant leaves extract. It reduced significantly (p<0.05) liver enzyme levels for animals treated with CCL4 (0.5 mL kg-1) and the methanolic plant leaf extract (40 mg kg-1) concurrently compared to animals treated with CCL4 only. Many histopathological changes in the liver such as marked dilation of the central vein, blood vessel congestion and inflammatory leucocytic infiltrations which were observed in the CCl4 treated animals were not observed in the CCl4 + plant extract treated animals. No apparent disruptions of the normal liver structure by histological and enzyme activities assessment were observed. The results show that the methanolic leaf extract is a potent analgesic and antihepatotoxic agent

    Quark and lepton masses and mixing from a gauged SU(3)_F family symmetry with a light O(eV) sterile Dirac neutrino

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    In the framework of a complete vector-like and universal gauged SU(3)_F family symmetry, we report a global region in the parameter space where this approach can account for a realistic spectrum of quark masses and mixing in a 4 x 4 non-unitary V_{CKM}, as well as for the known charged lepton masses and the squared neutrino mass differences reported from neutrino oscillation experiments. The SU(3)FSU(3)_F family symmetry is broken spontaneously in two stages by heavy SM singlet scalars, whose hierarchy of scales yield and approximate SU(2)_F global symmetry associated to the almost degenerate boson masses of the order of the lower scale of the SU(3)_F SSB. The gauge symmetry, the fermion content, and the transformation of the scalar fields, all together, avoid Yukawa couplings between SM fermions. Therefore, in this scenario ordinary heavy fermions, top and bottom quarks and tau lepton, become massive at tree level from Dirac See-saw mechanisms, while light fermions, including light neutrinos, obtain masses from radiative corrections mediated by the massive gauge bosons of the SU(3)_F family symmetry. The displayed fit parameter space region solution for fermion masses and mixing yield the vector-like fermion masses: M_D \approx 3.2 \,TeV, M_U \approx 6.9 \,TeV, M_E \approx 21.6 \,TeV, SU(2)_F family gauge boson masses of O(2TeV)\mathcal{O} (2 TeV), and the squared neutrino mass differences: m_2^2-m_1^2 \approx 7.5 x 10^{-5}\;eV^2, m_3^2-m_2^2 \approx 2.2 x 10^{-3}\;eV^2, m_4^2-m_1^2 \approx 0.82\;eV^2.Comment: 19 pages, 1 figure, Contribution to Proceedings of the 19th Workshop "What Comes Beyond the Standard Models", July 11-19, Bled, Slovenia. arXiv admin note: substantial text overlap with arXiv:1602.08212, arXiv:1212.457

    The industrial symbiosis approach: A classification of business models

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    Industrial symbiosis is a collaborative approach concerning physical exchange of materials, energy, and services among different firms: accordingly, wastes produced by a given firm are exploited as inputs by other firms. This approach is able to generate remarkable environmental benefits, since it allows to reduce the amount of wastes disposed of in the landfill and the amount of primary inputs used by the industrial sector. It has been proved that the economic logic is the basis of symbiotic exchanges. Through industrial symbiosis, firms are interested to achieve competitive advantage coming from lower production costs and revenue increase. Therefore, the first requirement for the establishment of a symbiotic relationship is its economic sustainability for all the firms involved. In this paper, from the analysis of actual cases of industrial symbiosis, we develop a classification of business models oriented to the symbiotic approach. The classification is based on the different ways in which industrial symbiosis is able to generate economic benefits for the firm that implements it. Six different business models oriented to industrial symbiosis have been identified. The proposed classification could be useful at the company level, in order to promote the implementation of the symbiotic approach, providing a guide about how to integrate it within its current business models

    The non-singlet kaon fragmentation function from e^+e^- kaon production

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    We perform fits to the available charged and neutral kaon production data in e++eK+Xe^++e^-\to K+X, K=K±andKS0K=K^\pm and K^0_S, and determine the non-singlet combination of kaon fragmentation functions DuK±DdK±D_u^{K^\pm}-D_d^{K^\pm} in a model independent way and without any correlations to the other fragmentation functions. Only nuclear isospin invariance is assumed. Working with non-singlets allows us to include the data at very low momentum fractions, which have so far been excluded in global fits, and to perform a first NNLO fit to fragmentation functions. We find that the kaon non-singlet fragmentation function at large zz is larger than that obtained by the other collaborations from global fit analysis and differs significantly at low zz
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