1,720,962 research outputs found
Melatonin treatment in spring and reproductive recovery in sheep with different body condition score and age.
No full textWith the aim to evaluate the effect of melatonin treatment on the advanced reproductive recovery in sheep with different body condition score (BCS) and age, 800 ewes were selected from two farms. These ewes (3-6 years old, multiparous and with BCS 2.5-4.0) were subdivided into two Groups (200 M and 200 C), balanced on their BCS and age. On 20 March, Group M was treated with one melatonin implant (18 mg). Group C was untreated. Males were introduced to the groups 35 days after treatment. Gestation was diagnosed between day 45 and 90 after mating by transabdominal ultrasonography. From day 150 to 190 after rams introduction, lambing date and newborns' number were recorded. The average time in days between male introduction and lambing resulted shorter in treated than in control ewes (166.4 ± 0.48 vs. 172.5 ± 0.50) (P < 0.05). At day 160 and 170 from ram introduction the fertility rate was higher in Group M than in C (P < 0.05). The overall fertility at day 190 from rams introduction showed no differences between Group M and C (337 and 339, respectively). At day 170 from male introduction the number of the 5-6 years-old lambed ewes were 2-fold higher than the youngers (P < 0.05). The animals with a BCS 3.5-4.0 had a faster response to male effect, and a shorter mean distance in days from rams introduction to lambing, compared to those scored 2.5-3.0 (166.1 ± 0.48 vs. 174.8 ± 0.51) (P < 0.05). We concluded that the ewes with BCS 3.5-4.0 and aged 5-6 years showed a better response to melatonin treatment in spring
Influences of melatonin treatment, melatonin receptor 1A (MTNR1A) and kisspeptin (KiSS-1) genes polymorphisms on first conception in Sarda ewe lambs
No full textIn order to investigate if the melatonin receptor 1A (MTNR1A) and kisspeptin (KiSS-1) genes influence the reproductive response to melatonin treatment, 510 Sarda ewe lambs were divided into groups C (control) and M; Group M received one melatonin implant (18mg). After 35 days rams were introduced for 40 days and subsequent lambing dates and number of newborns were recorded. The MTNR1A gene Exon II and KiSS-1 gene Exon I were amplified and genotyped by restriction fragment length polymorphism (RFLP) and single-strand conformation polymorphism analysis. Two single nucleotide polymorphisms (SNPs; C606T and G612A) in MTNR1A and one (G1035A) in KiSS-1 were found. The most frequent genotypes were G/G (63%) and C/C (53%) for MTNR1A and G/G (92%) for KiSS-1. Treated animals showed a higher lambing rate (P<0.05) and an advanced lambing date (P<0.05) compared with controls. The three SNPs did not influence the onset of reproductive activity. The majority of the G/G animals of Group M lambed before 190 days after ram introductio
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
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
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
Neurobiological, attentional and memory changes in posttraumatic stress disorder
Full text linkThis dissertation aimed at investigating the role of fear learning and encoding mechanisms in the development and maintenance of anxiety and trauma-related disorders in two studies.
In study 1, we combined functional resting state connectivity with skin conductance data of cued and contextual fear conditioning in 119 healthy individuals.
In study 2, we applied simultaneous high-density electroencephalography (EEG) with eye-tracking during free picture viewing (including traumatic cues in neutral contexts) and memory tests of the same materials in 20 patients with post-traumatic stress disorder (PTSD) and 20 trauma controls who did not develop PTSD (NPTSD). In study 1, we hypothesized that increased functional connectivity of the default mode network (DMN) (1) with the amygdala and frontal control regions would be associated with a decrease in the magnitude of cue aversive learning, and (2) that another DMN connectivity pattern including the hippocampal formation, would negatively correlate with the strength of contextual conditioning indices.
The main result of this study is that two different DMN patterns were identified in which stronger connectivity linked to lower differential SCRs during fear and anxiety was learning. One was related to cue conditioning and involved the amygdala and the medial prefrontal cortex, and one was associated with context conditioning and included the hippocampal formation and sensorimotor areas.
In the second study, we expected an early perceptual bias on trauma-related cues at the expense of the context in PTSD compared to NPTSD as visible in the modulation of polarity/amplitudes of the visual C1 and in eye tracking early fixation measures. Referring to the memory performance we expected the PTSD group to better retrieve pictures requiring a more elemental/unitary strategy (aka where the association between cues and contexts was kept constant) and consequently in being especially worse than NPTSD in retrieving cue-context modified associations. We finally expected encoding strategies to account for the memory performance.
In the simultaneous EEG-eye-tracking task we found that the PTSD but not the NPTSD group oriented more towards traumatic but not neutral cues at the expense of the context. These outcomes were present at the first stages of information processing as indicated by the changes in polarity of the C1 component of the EEG and predicted the following associative memory performance.
Different resting-state connectivity patterns within the DMN could emerge in association with individual predispositions of learning fear and anxiety.
Because of the recognized clinical implications of these learning mechanisms in trauma and anxiety disorders, our findings highlight the relevance of brain connectivity differences as possible biomarkers already at rest and in healthy individuals, for example in healthy populations with high exposure to traumatic events (such as medical personal, rescue workers, police officer, soldiers) in order to reduce vulnerability and/or promote resilience to develop PTSD.
An hippocampal processing impairment is probably responsible for the memory deficits in PTSD but possibly promoted from the strongly biased encoding strategy of the cues versus contexts, which also it is helpful in explaining intrusions and hyperarousal symptoms in a more complex perspective.
Moreover, increasing awareness encoding used strategies could help existing therapies (e.g. cognitive behavioral and exposure therapy) in modifying faster the appraisal and memory of the trauma through trained restructuring of events and contextual representations
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