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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 the food processing contaminant acrylamide and its metabolite glycidamide in human neural stem cells undergoing differentiation.
Get PDFOccupational exposure to the acrylamide (AA) monomer has been known since the 1960s to cause neurotoxicity of the central and peripheral nervous system. Concerns regarding exposure of the general populations arose upon discovering its natural formation in heated foodstuffs. AA is classified as a probable human carcinogen in addition to exhibiting genotoxic, reproductive, and developmental neurotoxic properties in experimental models. Adverse neurodevelopmental cognitive effects seen in animals have not yet been confirmed in humans. When absorbed from the gastrointestinal tract AA is metabolized mainly in the liver by CYP2E1 to glycidamide (GA). Both AA and GA are hydrophilic with wide distribution to organs and tissues. AA can reach the developing fetus via placental transfer and breast milk and prenatal exposure during pregnancy is associated with restricted fetal growth. It is unknown whether neurotoxicity is caused by AA itself or by GA. In this thesis, neural stem cells (NSCs) derived from human induced pluripotent stem cells were used to investigate the possible effect of exposure of AA and GA on key neurodevelopmental processes assessed by viability measurements, gene expression, and protein markers. The NSCs were differentiated and exposed to AA and GA (1x10-8 – 3x10-3 M) for up to 21 days. Effects on cell viability were measured using Alamar Blue™ Cell Viability assay upon exposure for 1, 3, 14, and 21 days. Alterations in gene expression of five genes were assessed using real-time PCR after exposure for 3, 14, and 21 days. Protein expression was qualitatively examined using immunocytochemistry and high content imaging after exposure for 14 and 21 days. The NSC cultures differentiated as expected, judged by changes in morphology seen in phase-contrast microscopy, gene, and protein expression of unexposed cells. Exposure to AA and/or GA at 1x10-8 M resulted in increased viability, whereas millimolar concentrations induced cytotoxicity in a time- and concentration-dependent manner. No statistically significant alterations in gene expression were observed. However, some trends were found although these may be of limited biological relevance. Expression of the astrocyte marker GFAP was not detected and should be further investigated using immunocytochemistry. Protein expression of neurodevelopmental markers did not reveal large differences in fluorescence intensity upon exposure. In conclusion, exposure to human-relevant concentrations of AA and GA increased cell viability with the most apparent effects for immature neurons, whereas higher concentrations resulted in cytotoxicity. Statistically significant alterations in the selected gene or protein expression of markers related to neurodevelopment were not observed.publishedVersio
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
Effects of polycyclic aromatic hydrocarbons (PAHs) on cell viability and gene expression related to neurite outgrowth in human neural stem cells undergoing differentiation
Get PDFPolycyclic aromatic hydrocarbons (PAHs) are widespread environmental pollutants formed
under incomplete combustions of organic materials such as the burning of fossil fuels, domestic
heating, automobile exhaust, cooking, and tobacco smoke. Some of the PAHs, like
benzo[a]pyrene (B[a]P), are known for their carcinogenic, genotoxic, and reproductive toxic
properties. Furthermore, concerns have been raised about the impact of PAHs on
neurodevelopment and possibly neurodevelopmental disorders, since accumulating evidence in
both animal and epidemiological studies points in the direction that PAH exposure can lead to
adverse effects on the developing brain. PAHs are lipophilic compounds and when inhaled they
can readily pass the placenta omitting the first path elimination in the liver. The fetus is therefore
at high risk due to limited protection by an immature blood-brain barrier and because of the
highly vulnerable dynamic complex processes during neurodevelopment. In this thesis, neural
stem cells derived from human induced pluripotent stem cells were used. This model can mimic
key neurodevelopmental differentiation processes, vital for normal brain development, which
were assessed by changes in cell viability, gene expression, and protein markers. The neural
stem cells were during differentiation to a complex neuronal network exposed to a wide
concentration range of three PAHs, namely B[a]P, β-naphthoflavone (β-NF), and pyrene for up
to 21 days. Effects on cell viability were measured with Alamar Blue™ Cell Viability assay
after exposure for 1, 3, 14, and 21 days. Changes in expression of genes related to
neurodevelopment were evaluated with real-time PCR after exposure for 3, 14, and 21 days.
Protein markers were qualitatively investigated with immunocytochemistry and high content
imaging after 14 and 21 days of exposure. The culture and differentiation processes developed
as expected, determined by changes in morphology and gene expression in addition to the
protein markers. Exposure to low concentrations of β-NF and pyrene increased cell viability,
while higher concentrations of particular B[a]P caused cytotoxicity. Minor alternations were
found in gene expression, and only one gene was statistically significantly changed upon
exposure. Expression of the astrocyte marker GFAP was unexpectedly not detected. Protein
expression of markers related to neurodevelopment was only qualitative and did not reveal any
visible differences after PAH exposure up to 21 days. In conclusion, exposure to the PAHs
increased cell viability at nanomolar concentrations of β-NF and pyrene, whereas micromolar
concentrations of B[a]P caused a decrease. The neurite outgrowth marker GAP43 was
statistically significantly increased after 21 days of exposure to the three PAHs. No visible
alterations in protein markers for neurodevelopment processes were observed.Polysykliske aromatiske hydrokarboner (PAHer) er en stor gruppe av miljøforurensende
stoffer/kjemikalier som dannes under ufullstendig forbrenning av organisk materiale. Utslipp
ses i sammenheng med husholdningsoppvarming, bileksos, matlagning og tobakksrøyk. Noen
PAHer, som benzo[a]pyren (B[a]P), er kjent for sin kreftfremkallende, gentoksiske og
reproduksjonstoksiske egenskaper. Bekymring rundt mulige nevroutviklingsforstyrrelser
indusert av PAHer, har blitt utrykt, etter akkumulerende bevis i både dyrestudier og
epidemiologiske studier. PAHer er fettløselige forbindelser, og når de inhaleres, kan de passere
morkaken og unngå første linje-elimineringen i leveren. Fosteret har derfor høy risiko for
eksponeringen som følge av den umodne blodhjerne-barrieren og de svært sårbare og
dynamiske prosessene under nevroutvikling.
I denne oppgaven ble nevrale stamceller utviklet fra human induserte pluripotente stamceller
benyttet. Cellemodellen kan etterligne viktige prosesser i human nevroutvikling/hjerneutvikling
og mulig endringer i slike prosesser ble undersøkt ved bruk av viabilitetsstudier, genuttrykk og
proteinmarkører. Nevrale stamceller ble, under differensiering, til et komplekst nettverk av
nevroner eksponert for ulike konsentrasjoner av PAHer i opptil 21 dager. PAHer som ble
benyttet var B[a]P, β-naftoflavon (β-NF) og pyrene. Effekter på celleviabilitet ble målt med
Alamar Blue™ etter eksponering i 1, 3, 14 og 21 dager. Endring i genuttrykk ble analysert med
sanntids-PCR etter eksponering i 3, 14 og 21 dager. Proteinmarkører ble undersøkt kvalitativt
med immuncytokjemi og visualisert med høyoppløselighetbilledtakning etter eksponering i 14
og 21 dager. Cellekulturen og differensieringsprosessen utviklet seg som forventet, som vist
ved endringer i morfologi, genuttrykk og forekomst av proteinmarkører. Eksponering for lave
konsentrasjoner av β-NF og pyren førte til en økning i celleviabilitet, mens høye
konsentrasjoner av særlig B[a]P forårsaket cytotoksisitet. Mindre endringer ble funnet i
genuttrykk, og kun et gen var statistisk signifikant endret etter eksponering. Genuttrykk av
GFAP ble ikke funnet og bør videre undersøkes. Proteinutrykk av markører relatert til
nevroutvikling og morfologi var kun kvalitativt vurdert, og ingen åpenbare forskjeller ble
funnet etter PAH-eksponering i opptil 21 dager. Det konkluderes med at PAH-eksponering av
nanomolare konsentrasjoner av β-NF og pyren økte celleviabiliteten, mens mikromolare
konsentrasjoner av den mulige kreftfremkallende PAH-forbindelsen B[a]P forårsaket en
reduksjon. Nevrittutvekstmarkøren GAP43 ble statistisk signifikant økt etter 21 dager
eksponering. Ingen åpenbare endringer i proteinutrykk ble observert.publishedVersio
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
Effects of the food processing contaminant acrylamide and its metabolite glycidamide in human neural stem cells undergoing differentiation
Get PDFOccupational exposure to the acrylamide (AA) monomer has been known since the 1960s to cause neurotoxicity of the central and peripheral nervous system. Concerns regarding exposure of the general populations arose upon discovering its natural formation in heated foodstuffs. AA is classified as a probable human carcinogen in addition to exhibiting genotoxic, reproductive, and developmental neurotoxic properties in experimental models. Adverse neurodevelopmental cognitive effects seen in animals have not yet been confirmed in humans. When absorbed from the gastrointestinal tract AA is metabolized mainly in the liver by CYP2E1 to glycidamide (GA). Both AA and GA are hydrophilic with wide distribution to organs and tissues. AA can reach the developing fetus via placental transfer and breast milk and prenatal exposure during pregnancy is associated with restricted fetal growth. It is unknown whether neurotoxicity is caused by AA itself or by GA. In this thesis, neural stem cells (NSCs) derived from human induced pluripotent stem cells were used to investigate the possible effect of exposure of AA and GA on key neurodevelopmental processes assessed by viability measurements, gene expression, and protein markers. The NSCs were differentiated and exposed to AA and GA (1x10-8 – 3x10-3 M) for up to 21 days. Effects on cell viability were measured using Alamar Blue™ cell viability assay upon exposure for 1, 3, 14, and 21 days. Alterations in gene expression of five genes were assessed using real-time PCR after exposure for 3, 14, and 21 days. Protein expression was qualitatively examined using immunocytochemistry and high content imaging after exposure for 14 and 21 days. The NSC cultures differentiated as expected, judged by changes in morphology seen in phase-contrast microscopy, gene, and protein expression of unexposed cells. Exposure to AA and/or GA at 1x10-8 M resulted in increased viability, whereas millimolar concentrations induced cytotoxicity in a time- and concentration-dependent manner. No statistically significant alterations in gene expression were observed. However, some trends were found although these may be of limited biological relevance. Expression of the astrocyte marker GFAP was not detected and should be further investigated using immunocytochemistry. Protein expression of neurodevelopmental markers did not reveal large differences in fluorescence intensity upon exposure. In conclusion, exposure to human-relevant concentrations of AA and GA increased cell viability with the most apparent effects for immature neurons, whereas higher concentrations resulted in cytotoxicity. Statistically significant alterations in the selected gene or protein expression of markers related to neurodevelopment were not observed.Siden 1960-tallet har det vært kjent at eksponering for akrylamid (AA) monomer forårsaker nevrotoksisitet i det sentrale og perifere nervesystemet. Bekymring for eksponering av den generelle befolkningen oppsto etter oppdagelsen av AA i varmebehandlet mat. AA er klassifisert som et mulig humant karsinogen i tillegg til å besitte gen-, reproduktivt- og utviklingstoksiske egenskaper i eksperimentelle studier. Alvorlige kognitive effekter sett i dyrestudier har ikke blitt bekreftet i humane studier til dags dato. AA tas opp fra mage-tarmkanalen og metaboliseres hovedsakelig i leveren av CYP2E1 til glysidamid (GA). Både AA og GA er vannløselige og distribueres i vannfasen til de fleste indre organer og vev. AA kan nå barnet gjennom overføring via morkaken og morsmelk og prenatal eksponering under svangerskapet er assosiert med begrenset fostervekst. Det er derimot ukjent om det er AA eller GA som forårsaker nevrotoksisiteten som er assosiert med eksponering. I denne oppgaven ble nevrale stamceller, opparbeidet fra humane induserte pluripotente stamceller, brukt til å undersøke effekten av eksponering på prosesser viktige i den humane hjerneutviklingen. Stamcellene ble differensiert og eksponert for AA og GA (1x10-8 – 3x10-3 M) i opptil 21 dager og undersøkt ved bruk av viabilitetsmålinger, genuttrykk og proteinmarkører. AA og GA sin påvirkning på cellenes viabilitet ble undersøkt med Alamar Blue™ viabilitetsanalyse etter eksponering i 1, 3, 14 og 21 dager. Endringer i genuttrykket av fem utvalgte gener ble undersøkt ved sanntids-PCR etter eksponering i 3, 14 og 21 dager. Etter eksponering i 14 og 21 dager ble det kvalitative proteinuttrykket undersøkt med immuncytokjemi og høyoppløselighets-billedtagning. Kulturen utviklet seg som forventet vurdert etter endringer i morfologi ved bruk av fasekontrastmikroskopi, gen og protein markører av ueksponerte celler. AA og GA påvirket viabiliteten til cellene hvor 1x10-8 M medførte økt viabilitet mens millimolare konsentrasjoner resulterte i celledød på en tids- og konsentrasjonsavhengig måte. Det ble observert ikke-statistisk signifikante endringer og trender i genuttrykket, men som er av begrenset human relevans. Genuttrykket av astrocyttmarkøren GFAP ble ikke påvist og bør undersøkes nærmere med immuncytokjemi. Ingen større forskjeller i fluorescensintensitet ble observert for proteinmarkørene. I denne oppgaven ble det konkludert med at human relevante konsentrasjoner av AA og GA medførte en økning i viabilitet mest synlig for umodne nevroner mens høyere konsentrasjoner medførte celledød. Ingen statistisk signifikante endringer i gen- eller proteinuttrykk av relevante nevroutviklingsmarkører ble observert i denne studien.publishedVersio
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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