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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
Effects of persistent organic pollutants (POPs) on the steroidogenesis of primary neonatal porcine Leydig cells
No full textAfter World War II the production of manmade chemicals has increased immensely. They are made to give desired practical properties and functions. Some are added to consumer products to provide conductivity, increase flame resistance, as plasticizer and some act as both grease and water repellants. Others are widely used as pesticides and fungicides.
A number of these compounds are spread via water, air, soil leading to exposure of living
organisms, including humans. Of particular concern are so-called Persistent Organic Pollutants (POPs), which break down slowly, bio-accumulate in the food web and spread though water and air which make these compounds reach places far from where they have been used or produced.
Since the late 1960s exposures to POPs has been associated with disturbance of the reproductive function of birds and fish affecting the hormone systems. Thinning of bird eggshell due to exposure of the pesticide dichlorodiphenyltrichloroethane (DDT) was one of the earliest published reports to get much publicity. Not long after, DDT was banned as a pesticide in Europe and northern America and comities were formed to protect the environment against POPs with harmful effects. Exposures of POPs occur as complex mixtures of POPs in the environment. One POP alone can have different effect than as part of a mixture of many POPs. Further, POPs can break down to metabolites with more and different effects than the mother substances, which also is shown with DDT and its metabolites.
In Paper I of this thesis, POPs mixtures extracted from fish oil were exposed to unstimulated and LH-stimulated primary neonatal porcine Leydig cells. The endpoints studied were toxicity,
hormone secretion of testosterone (T) and estradiol 17β (E2) in addition to gene expression of selected steroidogenic genes. The three other papers investigated the same endpoints in the same primary cells exposure to the DDT-metabolites; o,p’-DDD, 3-MeSO2-DDE and 3,3’-(bis)MeSO2-DDE. The exception was Paper III, where proteomic analysis was used instead of gene expression. In this article a broad range of proteins were investigated in unstimulated and LH-stimulated cells exposed to 3-MeSO2-DDE. With this we wanted to get closer to an explanation of the effects found in Paper II, and especially why we get increased dose related secretion of hormones in unstimulated cells while reduced secretion was found in LH-stimulated cells.
The target for all of our studies was to investigate the effects on hormone secretion at
concentrations of POPs or DDT-metabolites not related to cell toxicity. Of the DDTvii
metabolites, o,p’-DDD showed toxicity at concentrations ≥10 μM (Paper IV). Some toxicity was also observed in LH-stimulated cells exposed to 3-MeSO2-DDE at concentrations ≥20 μM (Paper II).
This thesis contain studies in which differential or partly differential effects with regard to
hormone secretion were observed with DDT metabolites and POPs mixtures dependent on whether they were stimulated with LH or not. All POPs mixtures from fish oil and DDT
metabolites caused reduced secretion of E2 and T in LH-stimulated Leydig cells while
increased secretion of hormones was found in unstimulated Leydig cells (Paper I-IV).
The expression of selected genes relevant to the steroidogenesis were mainly downregulated in LH-stimulated and unstimulated Leydig cells exposed to the POP mixtures and DDT metabolites (Paper I, II, IV). The genes STAR, CYP11A, HSD3B, CYP17A1 and CYP19A1 were most often affected.
In the proteomic study (Paper III) exposing 3-MeSO2-DDE to Leydig cells 145 proteins in LH-stimulated cells and 86 proteins in unstimulated cells were regulated by 3-MeSO2-DDE. Eleven of these proteins were common for each culture condition. This study indicated that multiple pathways were affected by exposure, including mitochondrial function, oxidative phosphorylation, eukaryotic initiation factor 2 (EIF2) signaling, glutathione detoxification. These results can give a base for new mechanistic studies.
Our studies showed that POPs mixtures extracted from fish and the DDT metabolites; o,p’-DDD, 3-MeSO2-DDE and 3,3’-(bis) MeSO2-DDE alters secretion of the hormones E2 and T differently dependent on the presence of absence of LH-stimulation. The Proteomic study (Paper III) indicated that environmental pollutants can affect important cell functions that may indirectly affect hormone secretion of the cell. These results can give grounds for future mechanistic studies
Effekter av persistente organiske miljøgifter på steroidogenesen i primære neonatale Leydigceller fra gris
Get PDFAfter World War II the production of manmade chemicals has increased immensely. They are made to give desired practical properties and functions. Some are added to consumer products to provide conductivity, increase flame resistance, as plasticizer and some act as both grease and water repellants. Others are widely used as pesticides and fungicides.
A number of these compounds are spread via water, air, soil leading to exposure of living
organisms, including humans. Of particular concern are so-called Persistent Organic Pollutants (POPs), which break down slowly, bio-accumulate in the food web and spread though water and air which make these compounds reach places far from where they have been used or produced.
Since the late 1960s exposures to POPs has been associated with disturbance of the reproductive function of birds and fish affecting the hormone systems. Thinning of bird eggshell due to exposure of the pesticide dichlorodiphenyltrichloroethane (DDT) was one of the earliest published reports to get much publicity. Not long after, DDT was banned as a pesticide in Europe and northern America and comities were formed to protect the environment against POPs with harmful effects. Exposures of POPs occur as complex mixtures of POPs in the environment. One POP alone can have different effect than as part of a mixture of many POPs. Further, POPs can break down to metabolites with more and different effects than the mother substances, which also is shown with DDT and its metabolites.
In Paper I of this thesis, POPs mixtures extracted from fish oil were exposed to unstimulated and LH-stimulated primary neonatal porcine Leydig cells. The endpoints studied were toxicity,
hormone secretion of testosterone (T) and estradiol 17β (E2) in addition to gene expression of selected steroidogenic genes. The three other papers investigated the same endpoints in the same primary cells exposure to the DDT-metabolites; o,p’-DDD, 3-MeSO2-DDE and 3,3’-(bis)MeSO2-DDE. The exception was Paper III, where proteomic analysis was used instead of gene expression. In this article a broad range of proteins were investigated in unstimulated and LH-stimulated cells exposed to 3-MeSO2-DDE. With this we wanted to get closer to an explanation of the effects found in Paper II, and especially why we get increased dose related secretion of hormones in unstimulated cells while reduced secretion was found in LH-stimulated cells.
The target for all of our studies was to investigate the effects on hormone secretion at
concentrations of POPs or DDT-metabolites not related to cell toxicity. Of the DDTvii
metabolites, o,p’-DDD showed toxicity at concentrations ≥10 μM (Paper IV). Some toxicity was also observed in LH-stimulated cells exposed to 3-MeSO2-DDE at concentrations ≥20 μM (Paper II).
This thesis contain studies in which differential or partly differential effects with regard to
hormone secretion were observed with DDT metabolites and POPs mixtures dependent on whether they were stimulated with LH or not. All POPs mixtures from fish oil and DDT
metabolites caused reduced secretion of E2 and T in LH-stimulated Leydig cells while
increased secretion of hormones was found in unstimulated Leydig cells (Paper I-IV).
The expression of selected genes relevant to the steroidogenesis were mainly downregulated in LH-stimulated and unstimulated Leydig cells exposed to the POP mixtures and DDT metabolites (Paper I, II, IV). The genes STAR, CYP11A, HSD3B, CYP17A1 and CYP19A1 were most often affected.
In the proteomic study (Paper III) exposing 3-MeSO2-DDE to Leydig cells 145 proteins in LH-stimulated cells and 86 proteins in unstimulated cells were regulated by 3-MeSO2-DDE. Eleven of these proteins were common for each culture condition. This study indicated that multiple pathways were affected by exposure, including mitochondrial function, oxidative phosphorylation, eukaryotic initiation factor 2 (EIF2) signaling, glutathione detoxification. These results can give a base for new mechanistic studies.
Our studies showed that POPs mixtures extracted from fish and the DDT metabolites; o,p’-DDD, 3-MeSO2-DDE and 3,3’-(bis) MeSO2-DDE alters secretion of the hormones E2 and T differently dependent on the presence of absence of LH-stimulation. The Proteomic study (Paper III) indicated that environmental pollutants can affect important cell functions that may indirectly affect hormone secretion of the cell. These results can give grounds for future mechanistic studies.Etter andre verdenskrig har produksjonen av menneskeskapte kjemikalier økt kraftig. De er skapt for å gi ulike produkter ønskede egenskaper, eksempelvis, strømledende, flammeavstøtende, plastifiserende, fett- og vannavstøtende. I tillegg finnes plantevernmidler som er laget for å hemme eller forebygge angrep av skadedyr, sopp og ugras som skader planter.
Ulempen med mange av disse forbindelsene er at de brytes ned sakte og akkumuleres i næringskjeder. Disse kjemiske forbindelsene kalles gjerne persistente organiske forurensningsstoffer og benevnes gjerne som POPs (engelsk: Persistent Organic Pollutants). Spredning gjennom vann og luft gjør at disse stoffene kan ende opp langt fra steder de er benyttet eller produsert.
Sent på 1960 tallet ble det oppdaget at eksponering for POPs kunne være forbundet med skade på forplantningsevnen hos fugl og fisk. Tynning av fugleskall på grunn av eksponering for plantevernmiddelet dichlorodiphenyltrichloroethane (DDT) var et av de første funnene som fikk mye publisitet. Ikke lenge etter ble DDT forbudt som plantevernmiddel i Europa og NordAmerika, og det ble iverksatt tiltak for å redusere utslipp av POPs med skadelige effekter. POPs forekommer som komplekse blandinger i miljøet. Effekter av disse kan ha andre effekter enn stoffene enkeltvis. POPs blir nedbrutt i varierende grad til metabolitter som kan gi andre effekter enn morsubstansen. Dette er også vist med DDT og dets metabolitter.acceptedVersio
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
Studies of boar taint, with an emphasis on testicular function and development
Get PDFBoar taint is an odour reminiscent of sweat, urine or faeces, perceived as off-flavour when meat from entire male swine is heated. The compunds that cause boar taint are androstenone and skatole/indole. Androstenone is secreted as a testis steroid, while skatole/indole originates in the large intestine. Environmental factors do not have much impact on androstenone levels. Castration is therefore used to eliminate the site of androstenone synthesis. This also influences skatole degradation, which is inhibited by androstenone in the liver. However, surgical castration is being phased out for animal welfare reasons, so that alternative ways of reducing boar taint is needed.
Heritability for androstenone levels is high, so that breeding for lower levels is possible. However, this will only be successful if unwanted side effects can be avoided. Side effects include lower levels of other sexual steroids and delayed sexual maturation in both boars and gilts. Breed differences in adrostenone levels and sexual maturation have also been shown.
The principal aim of this thesis was to investigate the relationships between levels of androstenone and other testis steroids and testis development, including interactions between genotype, phenotype and breed differences.Hanngriser utsondrer en urin-faecal-aktig kroppslukt som gjerne betegnes som rånelukt. Denne kan oppfattes som frastøtende når kjøtt fra hanngriser varmes opp. Lukten fra hanngriser kommer fra skatol/indol og androstenon. Skatol og indol blir dannet i tykktarmen. Nivåene av skatol og indol kan påvirkes av foring og hygienisk standard, men det er også en betydelig arvelig komponent. Vekselvirkninger i leveren gjør at nedbrytingen av skatol påvirkes av androstenon.
Ettersom androstenon dannes sammen med steroidene i testiklene, har det vært vanlig å kastrere griser kirurgisk for å eliminere kjønnslukten. Kastrering ved kirurgisk inngrep fases ut grunnet dyrevernhensyn. Derfor er det etterspørsel etter bærekraftige alternativer for å redusere nivåene av androstenon.
Den høye arveligheten åpner for at nivåer av androstenon kan påvirkes gjennom avl, men slike tiltak kan først forventes når det blir mulig å unngå bieffekter av avlen. Slike bieffekter er lavere steroidnivåer og forsinket kjønnsmodning hos begge kjønn. I tillegg bidrar raseforskjeller for både androstenonnivåer og kjønnsmodning til å komplisere problemstillingen.
Hovedformålet med avhandlingen var å studere forholdet mellom androstenon, andre steroider med opphav i testikkelen og testikkelutvikling. Interaksjoner mellom genotype, fenotype og raseforskjeller var også inkludert.Astri og Birger Torstedts Legat id:2298 and Eivind Eckbos Lega
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
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
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