1,720,958 research outputs found
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Comparison of qPCR-HRM and fragment analysis methods to determine the methylation status of the MLH1 gene promoter in tumor samples
No full textRak debelega črevesa in danke ter rak endometrija sta dve izmed pogostejših oblik raka v svetu in v Sloveniji. Vzrok za njun nastanek je lahko sindrom Lynch (ang. Lynch syndrome, LS), ki je avtosomno dominantno dedna predispozicija za razvoj rakavih bolezni. Sindrom Lynch je povezan z okvaro genov MLH1, MSH2, MSH6, PMS2 in EPCAM, izmed katerih prvi štirje geni kodirajo proteine, ki sestavljajo kompleks, ki je vključen v mehanizem popravljanja neujemanja baznih parov v DNA (ang. DNA mismatch repair, MMR). Vzrok za nastanek raka debelega črevesa in danke ter raka endometrija pa je lahko tudi sporadična oblika raka, ki je posledica hipermetilacije promotorja gena MLH1. Razlikovanje med vzrokom za nastanek raka je pomembno zaradi nadaljnje obravnave posameznika. Za določanje prisotnosti hipermetilacije promotorja gena MLH1 lahko uporabimo številne metode, med njimi tudi MS-MLPA (za metilacijo specifična metoda od ligacije odvisnega hkratnega pomnoževanja sond, ang. methylation-specific multiplex ligation-dependent probe amplification) in qPCR-HRM (za metilacijo občutljiva metoda kvantitativne verižne reakcije s polimerazo in analize talilne krivulje visoke ločljivosti, ang. methylation-sensitive quantitative PCR high-resolution melting). Metoda MS-MLPA je v laboratoriju za molekularno genetiko, KIGM, UKC Ljubljana, že vpeljana, kot cilj tega magistrskega dela pa smo si zastavili optimizacijo in overitev metode qPCR-HRM. Uporabili smo DNA iz 25 vzorcev tkiva fiksiranega in vklopljenega v parafin ter primerjali skladnost rezultatov analize qPCR-HRM in MS-MLPA. Rezultati analiz qPCR-HRM in MS-MLPA so bili skladni, s čimer smo metodo overili. S tem smo pomembno dopolnili nabor preiskav, ki jih opravimo pri bolnikih z rakom, in s tem zmanjšali število oseb, ki bi sicer bile napotene na genetski posvet zaradi suma na LS.Colorectal cancer and endometrial cancer are among the most common forms of cancer globally and in Slovenia. One potential cause for their development is Lynch syndrome (LS), an autosomal dominant hereditary predisposition for the development of cancers. Lynch syndrome is associated with pathogenic variant in the MLH1, MSH2, MSH6, PMS2, and EPCAM genes. The first four of these genes encode proteins that form a complex involved in the DNA mismatch repair mechanism (MMR). However, the development of colorectal and endometrial cancers can also be attributed to sporadic cases, often resulting from hypermethylation of the MLH1 gene promoter region. Distinguishing between hereditary and sporadic causes of cancer is essential for appropriate patient management. Several methods are available for determining the presence of hypermethylation in the MLH1 promoter region, including MS-MLPA (methylation-specific multiplex ligation-dependent probe amplification) and qPCR-HRM (methylation-sensitive quantitative PCR high-resolution melting). The MS-MLPA technique has already been established in the Laboratory of Molecular Genetics at the Clinical Institute of Genomic Medicine (KIGM), University Medical Center Ljubljana (UKC Ljubljana). The aim of this master\u27s thesis was to optimize and validate the qPCR-HRM method. We used DNA isolated from 25 formalin fixed paraffin embedded tissue samples, comparing the results of qPCR-HRM analysis with those obtained from the MS-MLPA method. Validation of the qPCR-HRM method was achieved by confirming that the results were consistent with those from the MS-MLPA analysis. This advancement significantly expands the range of diagnostic tests available for cancer patients. Consequently, reducing the number of individuals unnecessarily referred for genetic counselling due to suspected LS
The impact of maternal nutrition during pregnancy and postpartum on child development
Get PDFEpigenetske modifikacije sodijo med najpomembnejše mehanizme preko katerih lahko okoljski dejavniki vplivajo na zgodnjo celično diferenciacijo in ustvarijo nove fenotipske lastnosti med nosečnostjo in v zgodnjem otroštvu, ne da bi spremenili zaporedje deoksiribonukleinske kisline. Številni predporodni in poporodni dejavniki, na primer prehrana matere in novorojenčka, izpostavljenost polutantom in sestava mikrobiote, prispevajo k vzpostavitvi epigenetskih modifikacij, ki ne vplivajo samo na posameznikovo prilagoditev okolju, ampak tudi na vseživljenjsko zdravje in bolezni s spreminjanjem signalnih poti in imunskega odziva. Poporodna črevesna kolonizacija, ki jo določa materinska mikrobiota in prehrana novorojenčka, privede do specifičnih epigenetskih modifikacij, ki lahko vplivajo na lastnosti črevesne sluznice in njihovo zaščitno vlogo pri razvoju vnetnih bolezni kasneje v življenju. Pri sesalcih sta dve glavni časovni obdobji, kjer se epigenom izbriše in ponovno vzpostavi, to sta gametogeneza in razvoj plodu. Razvoj plodu ima tri razvojne stopnje, obdobje pred implantacijo, v obdobju razvoja zarodka ter poporodna tranzicija. Zato je že prehrana ženske pred zanositvijo velik dejavnik, ki vpliva na razvoj otroka. Prav tako morata biti nosečnica v vseh stopnjah razvoja ploda in doječa mati zelo previdni pri prehrani, saj premalo raznolika hrana ali hrana bogata s posameznimi hranili privede do sprememb metilacijskih motivov, ki vplivajo na razvoj bolezni. Vloga prehrane matere v času nosečnosti in po porodu, prehrane otroka in njegove mikrobiote in drugih prehranskih dejavnikov močno vpliva pri določanju epigenetskih modifikacij in njihovih kratko- in dolgoročnih učinkov na zdravje in razvoj otroka.Epigenetic modifications are among the most important mechanisms through which environmental factors can influence early cell differentiation and create new phenotypic traits during pregnancy and early childhood without altering the deoxyribonucleic acid sequence. Many prenatal and postpartum factors, such as maternal and neonatal nutrition, pollutant exposure, and microbiota composition, contribute to the establishment of epigenetic modifications that affect not only an individual’s adaptation to the environment but also lifelong health and disease by altering signaling pathways and immune responses. Postpartum intestinal colonization, determined by the maternal microbiota and neonatal nutrition, leads to specific epigenetic modifications that may affect intestinal mucosal properties and their protective role in the development of inflammatory diseases later in life. In mammals, there are two main time periods where the epigenome is erased and re-established, namely gametogenesis and fetal development. Fetal development has three developmental stages, the period before implantation, the period of embryonic development, and the postpartum transition. Therefore, even woman\u27s diet before they want to conceive is a big factor influencing a child’s development. Also, a pregnant woman at all stages of fetal development and a breastfeeding mother should be very careful in their diet, as insufficiently varied foods or foods rich in individual nutrients lead to changes in methylation motives that affect the development of the disease. The role of maternal nutrition during pregnancy and after childbirth, the child\u27s diet and its microbiota and other nutritional factors strongly influence the determination of epigenetic modifications and their short- and long-term effects on the health and development of the child
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe 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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