1,721,106 research outputs found
The nucleon Drell-Hearn-Gerasimov sum rule within a relativistic constituent quark model
No full textWe investigate the Drell-Hearn-Gerasimov sum rule within a relativistic constituent quark model based on the light-front formalism.The contribution of the nucleon to Delta transition is explicitly evaluated using different forms of the baryon wave functions and adopting a one-body relativistic current which includes Dirac and Pauli form factors for the constituent quark
Synthesis and sar study of 2-substituted imidazo[2,1-b] [1,3]benzothiazoles and related compounds endowed with affinity for dopamine d2 receptors as potential antipsychotics
No full textSchizophrenia is a complex disorder affecting approximately 1% of the population.
Typical antipsychotic agents such as chlorpromazine and haloperidol block the D2 subtype of
dopamine receptors in a direct relation to their clinical potency. However, although blockade of
D2 receptors improves the positive symptoms of the disease, it also accounts for side effects which
strongly limit patient compliance, in particular extrapyramidal effects and hyperprolactinemia.
During the past few years, a second generation of antipsychotic agents has emerged
(e.g.,clozapine, risperidone, olanzapine, and ziprasidone); they are categorized as atypical in
contrast to conventional D2 blockers and exhibit a dual dopaminergic and serotonergic mechanism
of action: a relatively weak dopamine D2 receptor antagonism in vitro and in vivo, but potentially
important activities at other dopaminergic (D1, D4) receptors, at serotonergic (5-HT1A, 5HT2A,
5HT3, 5HT2C), adrenergic (a1, a2), histaminergic (H1), and muscarinic receptors. They are claimed
to be active against both positive and negative symptoms of schizophrenia, even though they do
exhibit a variety of other side effects as weight gain, postural hypotension, sedation, dry mouth.
For these reasons the search for more effective and less toxic agents still continues [1,2].
In this context we have developed a series of (1,2-diphenyl-imidazolyl)piperazine
derivatives (1) that are endowed with substantial affinities for both dopamine D2 receptors as well
as 5-HT1A and 5-HT2A serotonin receptors, compound 1a (R = o-OCH3) of which is representative [3].
We have extended our study on other series of compounds derived from 1 both modifying
the 1,2-diphenyl motif attached to the imidazole core, and the phenyl-piperazine moiety.
All novel compounds were submitted by Lundbeck to radioligand binding assay on
dopamine, serotonin, adrenergic, histaminergic receptor subtypes. The chemistry and the in vitro
screening will be discussed in the poster
Leading and higher twists in the proton polarized structure function g1p at large Bjorken x
No full textA phenomenological parametrization of the proton polarized structure function g1p(x,Q2) is developed for x≳0.02 using deep inelastic data up to ∼50 (GeV/c)2 as well as available experimental results on both photo- and electroproduction of proton resonances. According to the new parametrization the generalized Drell-Hearn-Gerasimov sum rule is predicted to have a zero-crossing point at Q2=0.16±0.04 (GeV/c)2. Then, low-order polarized Nachtmann moments are estimated and their Q2 behavior is investigated in terms of leading and higher twists for Q2≳1 (GeV/c)2. The leading twist is treated at NLO in the strong coupling constant and the effects of higher orders of the perturbative series are estimated using soft-gluon resummation techniques. In the case of the first moment, higher-twist effects are found to be quite small for Q2≳1 (GeV/c)2, and the singlet axial charge has been determined to be a0[10 (GeV/c)2]=0.16±0.09. In the case of higher order moments, which are sensitive to the large-x region, higher-twist effects are significantly reduced by the introduction of soft gluon contributions, but they are still relevant at Q2∼ few (GeV/c)2 at variance with the case of the unpolarized transverse structure function of the proton. Our finding suggests that spin-dependent correlations among partons may have more impact than spin-independent ones. As a by-product, it is also shown that the Bloom-Gilman local duality is strongly violated in the region of polarized electroproduction of the Δ(1232) resonance
Synthesis and SAR study of 2-substituted imidazo[2,1-b][1,3]benzothiazoles and related compounds endowed with affinity for dopamine D2 receptors as potential antipsychotics
No full textGoing Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Extracting excited states from lattice QCD: the Roper resonance
No full textAbstractWe present a new method for extracting excited states from a single two-point correlation function calculated on the lattice. Our method simply combines the correlation function evaluated at different time slices so as to “subtract” the leading exponential decay (ground state) and to give access to the first excited state. The method is applied to a quenched lattice study (volume=243×64, β=6.2, a−1=2.55 GeV) of the first excited state of the nucleon using the local interpolating operator O=ɛabc[uaTCγ5db]uc. The results are consistent with the identification of our extracted excited state with the Roper resonance N′(1440). The switching of the level ordering with respect to the negative-parity partner of the nucleon, N*(1535), is not seen at the simulated quark masses and, basing on crude extrapolations, is tentatively expected to occur close to the physical point
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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