1,720,956 research outputs found
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
mutazioni somatiche e germinali nell'eziologia delle cardiopatie congenite
No full textLe cardiopatie congenite (CC) sono anomalie strutturali del cuore o dei grandi vasi e costituiscono il maggior numero delle malformazioni congenite alla nascita; conseguentemente rappresentano un importante problema dal punto di vista della salute pubblica.
I meccanismi molecolari alla base delle CC sono complessi e ancora oggi poco chiari.
Negli ultimi anni, modelli sperimentali di topo knockout hanno messo in evidenza il ruolo fondamentale di fattori di trascrizione cardiaci (TF's) durante la cardiogenesi, dimostrando come l'assenza del gene o la presenza di mutazioni in questi fattori siano responsabili di malformazioni cardiovascolari.
Studi di sequenziamento genico condotti su pazienti con CC hanno, infatti, evidenziato la presenza di mutazioni nei geni dei fattori di trascrizione in forme familiari sindromiche e non. Mutazioni nella linea germinale sono state identificate, sebbene raramente, anche in forme sporadiche di CC, con una frequenza inferiore al 3%.
Risulta, pertanto, evidente il ruolo di altri meccanismi molecolari che possono cooperare con i fattori genetici nell'eziologia delle CC come i meccanismi epigenetici e la presenza di mutazioni somatiche acquisite.
Pertanto, lo scopo della tesi è stato quello di verificare, attraverso uno screening genetico, la presenza di mutazioni, germinali e somatiche, nei geni Gata 4 e Nkx 2.5 sia in pazienti con CC familiare che con CC sporadica.
L'analisi mutazionale dei geni Gata4 e Nkx2.5 è stata effettuata su un totale di 10 pazienti affetti da CC afferenti presso l'Ospedale Pasquinucci di Massa. Di questi, 5 avevano una storia positiva familiare (2 maschi; età 24 mesi ± 36) e 5 erano casi sporadici (1 maschio; età 35 mesi ± 67) e risultavano appaiati per il tipo di CC (Tof, DIV, DIA, Truncus Arteriosus, DIV+DIA). Dai pazienti con CC familiare abbiamo ottenuto un piccolo campione di sangue (5 cc) periferico dal quale è stato estratto il DNA genomico, mentre dai pazienti con una forma sporadica di CC abbiamo analizzato il DNA estratto da un campione bioptico di tessuto cardiaco.
Il sequenziamento genico per il gene Gata4 ha evidenziato la presenza di molteplici varianti polimorfiche sia nelle regioni codificanti che non e nella regione 3'UTR in entrambi i gruppi di pazienti.
Abbiamo riscontrato il polimorfismo c.-543 c>t sia nei casi familiari (40%) sia nei casi sporadici (20%) con frequenze vicine a quelle descritte nella popolazione di controllo. In soli 2 casi familiari, nell'esone 6, è stata riscontrata una mutazione non-sinonima c.1130 A>G p.Ser377Gly, che si manifesta con una frequenza più elevata rispetto alla popolazione di controllo. Nelle regioni introniche del gene Gata4 abbiamo individuato diversi polimorfismi, sia nei casi familiari che sporadici con frequenze vicine a quelle della popolazione di controllo e tutti già precedentemente descritti.
In soli 2 casi familiari abbiamo osservato una variante +852 g>a nella regione 3’ UTR con una frequenza allelica del 30% e mai riportata prima.
Tuttavia, l'analisi genetica di 50 soggetti di controllo (45 maschi; età 47anni ± 16) ha evidenziato la presenza della variante genica con una frequenza allelica abbastanza elevata anche nella popolazione generale.
Per il gene Nkx2.5, abbiamo sequenziato le regioni codificanti e le vicine regioni introniche degli esoni 1 e 2. E' stato riscontrato un solo polimorfismo c.63 a>g E21E nell'esone 1 del gene, è una variante già descritta in letteratura, si presenta con una frequenza elevata nei casi sporadici (60%), nei casi familiari (60%) e nella popolazione di controllo(75%).
L'assenza di mutazioni patologiche sia nella linea germinale che in quella somatica sottolinea la possibilità che altri meccanismi molecolari, prevalentemente epigenetici, possano essere coinvolti nello sviluppo delle CC
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
Geneticsand epigenetics of congenital heart disease
No full textThe genetic architecture behind the development of congenital heart disease (CHD) still remains unclear, although CHD represents the most common type of birth defect affecting nearly 1% of live births. CHD occurs through heterogeneous and complex processes where common variants and/or (low/intermediate penetrance) mutations in genes critical for cardiac morphogenesis as well as dysregulation of post-transcriptional control play a crucial role.
The purpose of this thesis was to expand the knowledge about the etiology of CHDs through 3 main objectives:
1. to investigate the presence of gene mutations in key cardiac transcription factors in both germline and somatic cells;
2. to analyze the association between SNPs and haplotypes in the 3’UTR of candidate genes and CHD risk as well as their influence on the post-transcriptional control through the binding with specific miRNAs;
3. to investigate the presence of novel rare mutations in 17 genes related to CHD by using a next generation sequencing (NGS) approach.
We performed a Sanger sequencing of GATA4 and NKX2.5 genes in cardiac tissues of 15 sporadic (7 males; 12.4±7.5 years) and in blood samples of 15 familial (6 males; 14.1±9.0 years) patients with non-syndromic CHD. For each SNP in the 3’UTR, computational analysis was used to detect putative miRNAs and to assess the sum of all the Differences of Minimum Free Energy of hybridization (|ΔMFEtot| = Σ|ΔMFE|) in order to predict the biological importance of a SNP binding more miRNAs. Subsequently, we performed a validation reporter gene assay based on the luminescence generated by the luciferase protein, to validate the SNP whit the highest |ΔMFEtot| as a direct target of selected miRNAs. A case-control study and haplotype analysis were completed in order to define the association between the four common variants with the highest |ΔMFEtot| in the GATA4 3’UTR and the CHD risk.
A total of 12 DNA samples of CHD patients was sequenced in a NGS study by using the MiSeq® sequencing platform. The Design Studio included 17 genes related to CHD: NODAL, ZIC3, ELN, NKX2.5, JAG1, CFC1, LEFTY2, ACVR2B, GATA4, GATA6, GDF1, MYH6, TFAP2A, NOTCH1, TBX1, TBX20, and ZFPM2.
No evidence of novel GATA4 and NKX2.5 mutations was found in both sporadic and familial patients. However, we found several SNPs in the 3’UTR of GATA4 gene. Computational analysis revealed 27 putative miRNAs binding to GATA4 3'UTR variants. The most relevant |ΔMFEtot| (21.66 kcal/mol) was found for the miR-583, specifically targeting the +1521C>G SNP. A validation reporter gene assay based on the luminescence generated by the luciferase protein indicated that miR-583 was dose-dependently effective in regulating +1521 C allele compared with +1521 G allele.
The case-control study revealed that the +1158 C>T and +1521 C>G SNPs were significantly associated with the CHD risk (both, p=0.01). The haplotype analysis showed that the C-A-A-C haplotype (more common in CHD than controls) 4-fold increased the risk of CHD (p=0.04). Conversely, the T-T-G-C haplotype (more uncommon in CHDs) was associated with a significantly decreased CHD risk (p=0.035).
As regarded NGS, each single variant resulted from the targeted resequencing analysis has been annotated using the web application wANNOVAR (http://wannovar.usc.edu/) and the Ingenuity Variant Analysis software tool (Ingenuity Systems, QIAGEN), following specific parameters, as quality, frequency and pathogenicity. After filtering, the NGS analysis revealed 8 novel pathogenetic mutations, likely involved in the pathogenesis of CHD. Specifically, the mutations were identified mainly in genes (NOTCH1, MYH6, CFC1, GDF1, LEFTY2) that are related to left and/or right isomerism, involving transposition of the great arteries, tetralogy of Fallot and common atrioventricular canal anomalies.
These results provided important insights into the genetics of isolated, non-syndromic CHDs, underlining the need to investigate both the impact of SNPs on posttranscriptional mechanisms and the effects of novel, rare mutations with a low penetrance
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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