1,720,994 research outputs found
Morphologic maturation of tachykinin peptide-expressing cells in the postnatal rabbit retina
No full textTachykinin TK. peptides, which include substance P, neurokinin A, two neurokinin A-related peptides and neurokinin B, are widely
present in the nervous system, including the retina, where they act as neurotransmittersrmodulators as well as growth factors. In the
present study, we investigated the maturation of TK-immunoreactive IR. cells in the rabbit retina with the aim of further contributing to
the knowledge of the development of transmitter-identified retinal cell populations. In the adult retina, the pattern of TK immunostaining
is consistent with the presence of TK peptides in amacrine, displaced amacrine, interplexiform and ganglion cells. In the newborn retina,
intensely immunostained TK-IR somata are located in the ganglion cell layer GCL. and in the inner nuclear layer INL. adjacent to the
inner plexiform layer IPL.. They are characterized by an oval-shaped cell body originating a single process without ramifications. TK-IR
processes are occasionally observed in the IPL and in the outer plexiform layer OPL.. Long TK-IR fiber bundles are observed in the
ganglion cell axon layer. TK-IR profiles resembling small somata are rarely observed in the INL adjacent to the OPL. At postnatal day
PND. 2, some TK-IR cells display more complex morphologic features, including processes with secondary ramifications. Long TK-IR
processes in the IPL are often seen to terminate with growth cones. Between PND 6 and PND 11 eye opening., there is a dramatic
increase in the number of immunolabeled processes with growth cones both in the IPL and in the OPL and the mature lamination of
TK-IR fibers in laminae 1, 3 and 5 of the IPL is established. TK-IR cells attain mature morphological characteristics and the rare, putative
TK-IR somata in the distal INL are no longer observed. After eye opening, growth cones are not present and the pattern typical of the
adult is reached. These observations indicate that the development of TK-IR cells can be divided into an early phase from birth to PND
6. in which these cells establish their morphological characteristics, and a later phase from PND 6 to eye opening. in which they are
involved in active growth of their processes and likely in synapse formation. Since TK peptides are thought to play neurotrophic actions
in the developing nervous system and they are consistently present in the retina throughout postnatal development, they may also act as
growth factors during retinal maturation
Going 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
Agronomic-productive characteristics of two genotype of stevia rebaudiana in Central Italy
Full text linkStevia rebaudiana Bertoni produces a variety of high-potency low calorie sweeteners in its’ leaf tissue. The aim of this work was to evaluate the productive potential of two different Stevia rebaudiana genotypes and the characteristics of the production of the plant obtained through different cultivation methods, in central Italy. For several years (1992-2000) agronomic trials on Stevia rebaudiana cultivated in the littoral area near Pisa (Italy) carried out. In 1992 two different genotypes of Stevia (B1 and B2) transplanted in silt-loam soil; in 1996 other plants from B2 genotype, produced by vegetative process (micropropagation), were transplanted in the same field. In the period from 1992-1999 the production of leaves from both genotypes increase as of the third year and the ratio leaf-aerial plant, after the peak in the third year, tends to diminish. Except the first year (1997) there were not recorded statistically significant differences between the two propagation methods employed in relation to leaf production. The quantity of leaves produced from a single harvest was less than resulting from two cuttings and the micropropagation plants produced a larger amount of leaves than those from cutting. The leaf-stem ratio was to become an interesting morphological and production characteristic parameter of the plant. Stevia rebaudiana appears particularly suited for the cultivation environment of central Italy. A particular positive aspect that must be considered in these regions is that Stevia can be grown successfully as poliannual species because crop survival over the winter is high. The results obtained show that this species is economically profitable until the 5th or 6th year of cultivation. At our latitudes is also necessary to establish a program of genetic improvement in order to develop earlier varieties that can guaranty an optimum qualitative and quantitative seed production
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
Functional metalloproteins integrated with conductive substrates: Detecting single molecules and sensing individual recognition events
No full textIn the past decade, there has been significant interest in the integration of biomaterials with electronic elements: combining biological functions of biomolecules with nanotechnology offers new perspectives for implementation of ultrasensitive hybrid nanodevices. In particular, great attention has been devoted to redox metalloproteins, since they possess unique characteristics, such as electron-transfer capability, possibility of gating redox activity, and nanometric size, which make them appealing for bioelectronics applications at the nanoscale. The reliable connection of redox proteins to electrodes, aimed at ensuring good electrical contact with the conducting substrate besides preserving protein functionality, is a fundamental step for designing a hybrid nanodevice and calls for a full characterization of the immobilized proteins, possibly at the single-molecule level. Here, we describe how a multitechnique approach, based on several scanning probe microscopy techniques, may provide a comprehensive characterization of different metalloproteins on metal electrodes, disclosing unique information not only about morphological properties of the adsorbed molecules but also about the effectiveness of electrical coupling with the conductive substrate, or even concerning the preserved biorecognition capability upon adsorption. We also show how the success of an immobilization strategy, which is of primary importance for optimal integration of metalloproteins with a metal electrode, can be promptly assessed by means of the proposed approach. Besides the characterization aspect, the complementary employment of the proposed techniques deserves major potentialities for ultrasensitive detection of adsorbed biomolecules. In particular, it is shown how sensing of single metalloproteins may be optimized by monitoring the most appropriate observable. Additionally, we suggest how the combination of several experimental techniques might offer increased versatility, real-time response, and wide applicability as a detection method, once a reproducible correlation among signals coming from different single-molecule techniques is established
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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