1,721,016 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
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
MODELLING OF A THREE-PHASE TWO-WINDING LABORATORY TRANSFORMER WITH THE MATLAB SIMULINK PROGRAMME PACKAGE
No full textOsnovni zadatak ovog rada bio je istražiti metode za modeliranje trofaznog dvonamotnog transformatora koristeći programski paket MATLAB Simulink. Nakon analize različitih metoda, implementirana je odgovarajuća metoda i razvijen je laboratorijski model trofaznog dvonamotnog transformatora u MATLAB Simulink-u. Uspoređeni su rezultati dobiveni putem simulacijskog modela s rezultatima mjerenja na stvarnom transformatoru. Prvi dio rada daje opći uvod u transformatore, objašnjava njihov princip rada i analizira gubitke koji se javljaju tijekom njihovog rada. U drugom dijelu rada detaljno je opisan postupak određivanja parametara laboratorijskog modela trofaznog transformatora. To se postiže izvođenjem triju pokusa koji uključuju mjerenje radnog otpora VN i NN namota, pokus kratkog spoja i pokus praznog hoda. Opisana je detaljna procedura pokusa kao i rezultati mjerenja. Treći dio rada posvećen je modeliranju transformatora u MATLAB Simulink-u. Ovdje je opisana procedura potrebna za modeliranje transformatora, te su napravljeni pokusi kratkog spoja i praznog hoda. Na temelju usporedbe rezultata simulacije s rezultatima mjerenja na stvarnom transformatoru, potvrđena je valjanost izrađenog modela. Rad pruža korisnu maketu pomoću koje se mogu modelirati transformatori unutar MATLAB Simulink-a, koji se dalje mogu koristiti za testiranje rada i ponašanje transformatora pri različitim opterećenjima.The main objective of this thesis was to investigate methods for modelling a three-phase two-winding transformer using the MATLAB Simulink software package. After analysing different methods, a suitable method was implemented, and a laboratory model of a three-phase two-winding transformer was developed in MATLAB Simulink. The results obtained with the simulation model were compared with the measurement results of a real transformer. The first part of the thesis provides a general introduction to transformers, explains their operating principles and analyses the losses that occur during their operation. In the second part, the procedure for determining the parameters of the laboratory model of the three-phase transformer is described in detail. Three tests are carried out for this purpose, including measuring the resistance of the high-voltage and low-voltage windings, a short-circuit test and an open-circuit test. A detailed procedure for the tests and measurement results is described. The third part of the thesis is dedicated to modelling the transformer in MATLAB Simulink. It describes the procedure required for modelling the transformer, including the short-circuit and open-circuit tests. The validity of the developed model was confirmed by comparing the simulation results with the measurements on the real transformer. The thesis provides a useful framework for modelling transformers in MATLAB Simulink, which can be further used for testing the performance and behaviour of transformers under different load conditions
MODERN APPROACH TO TESTING THE DIFFERENTIAL PROTECTION OF TRANSFORMERS
No full textU ovome radu obrađena je problematika parametriranja i ispitivanja funkcije diferencijalne zaštite štićenog objekta, te komunikacija s numeričkim relejnim uređajem. Također, obrađene su vrste strujnih transformatora koji se koriste za diferencijalnu zaštitu visokonaponskih transformatora. Parametriziran je Siemensov zaštitni relej te je napravljeno i obrađeno sekundarno ispitivanje diferencijalne zaštite na fizičkom uređaju, kao i njegovom digitalnom blizancu. Napravljena je usporedba između fizičkog zaštitnog releja i njegovog digitalnog blizanca.This thesis deals with the parameterization and differential protection test functions of the protected object as well as the communication with a numerical relay device. It also covers the types of current transformers used for the differential protection of high-voltage transformers. The Siemens protection relay was parameterized, and a secondary differential protection test was performed and described in the case of the physical device and its digital twin. A comparison is made between the physical protection relay and its digital twin
Correlation between breast arterial calcifications and atherosclerotic changes of carotid arteries
No full textCiljevi provedenog istraživanja bili su: istražiti povezanost kalcificiranih arterija dojki na mamogramu i njihovog stupnja, s aterosklerotskim promjenama i njihovim stupnjem u karotidnim arterijama, odrediti povezanost određenih rizičnih čimbenika: dob, pušenje, dijabetes, hipertenzija i hiperlipidemija, BMI, periferna arterijska bolest, fibrilacija atrija, oralni kontraceptivi, te prethodni CVI/TIA/RIND/ sa stupnjem kalcifikacija intramamarnih arterija na mamogramu, i dokazati značaj mamografskog nalaza kalcificiranih arterija dojki kao važnog pokazatelja za postojanje aterosklerotskih promjena karotidnih arterija, te tako pridonijeti ranom otkrivanju rizika za cerebrovaskularnu bolest.
U ovom istraživanju je uključeno 300 ispitanica koje su razvrstane u dvije skupine: ispitivana skupina sa 149 ispitanica s arterijskim kalcifikacijama dojki na mamogramu, i kontrolna skupina sa 151 ispitanicom bez arterijskih kalcifikacija dojki na mamogramu. U ispitivanoj grupi su dvije podgrupe ispitanica - ispitanice s nježnim i ispitanice s intenzivnim kalcifikacijama. Svim ispitanicama učinjen je Dopler karotida, uzeti su anamnestički podaci i učinjene su laboratorijske pretrage.
Istraživanje je, temeljem statističke obrade, pokazalo statistički značajnu povezanost kalcificiranih arterija dojki na mamografiji, i stupanj ateroskleroze karotidnih arterija na ultrazvučnom Dopler testu kod ispitivanih. Obradom je utvrđena statistički značajna povezanost nalaza srednje intezivnih kalcificiranih arterija dojki i uzimanja oralne kontracepcije, te dobi ispitanica. Statistički nema značajne povezanosti arterijskih kalcifikacija dojki s rizičnim čimbenicima u krvi (kolesterol, trigliceridi, glukoza), pušenjem, konzumacijom alkohola, kardiovaskularnim bolestima i BMI. Dobiveni rezultati ovog ispitivanja su potvrdili statistički visoku korelaciju između grupe intenzivnih kalcifikacija arterija dojki i postojanja aterosklerotskih promjena u karotidnim arterijama. Logističkom regresijom utvrđeno je da je nalaz intenzivnih kalcifikacija značajan prediktor pozitivnog rezultata na Dopleru.
Ispitivanjem je potvrđena hipoteza, da nazočnost kalcificiranih stijenki arterija dojke na mamografskom pregledu, upućuje na veću vjerojatnost aterosklerotičnih promjena stijenki karotidnih arterija. Mamografski nalaz kalcificiranih stijenki arterija dojki predstavlja povećan rizik za postojanje aterosklerotskih promjena karotidnih arterija, koje su značajan čimbenik rizika cerebrovaskularne bolesti.Cerebrovascular diseases in all its forms according to the frequency and the high percentage of lethality and mortality are at the very top of the problems of modern medicine. The goal of modern medical science is the prevention of cerebrovascular disease . In this research breast arterial calcifications in mammograms were detected predominantly within The National programme of early detection of breast cancer in Croatia which has been implemented in the Republic of Croatia since 2006. The aim of the research was to investigate a connection between calcified arteries on breast mammograms and atherosclerotic changes in the carotid arteries. The second objective was to determine the association of certain risk factors : age , smoking, diabetes, hypertension and hyperlipidemia, BMI, peripheral artery disease, atrial fibrillation, oral contraceptives and previous stroke /TIA/RIND/IM with the degree of intramammary arterial calcifications on mammograms. The study aimed to assess the importance of mammography findings of breast arterial calcifications (finding to which attention was not paid in everyday diagnosis ) as an important indicator for the presence of atherosclerotic changes in the carotid arteries, and thus contribute to the early detection of the risk for cerebrovascular disease. This was a prospective study that included 300 women aged 47-69 years. Breast arterial calcifications were found in mammograms of 149 women while the control group consisted of 151 women without breast arterial calcifications in mammograms .
The hypothesis of the study was :
1. Mammographic finding of breast arterial calcifications represents an increased risk for the existence of atherosclerotic changes of the carotid arteries, which are a significant risk factor for cerebrovascular disease.
2. The degree of breast arterial calcification is correlated with the degree of atherosclerotic changes in the carotid artery and carotid artery stenosis assessed by ultrasound.
3. The occurrence of breast arterial calcification is associated with age, smoking, elevated blood glucose, high blood pressure, lipids, BMI (body mass index ), peripheral artery disease , previous stroke / TIA / RIND / MI , atrial fibrillation , taking oral contraceptives, hormon replacement therapy .
All patients were included in mammography and Doppler ultrasound of carotid arteries with the risk factor anlaysis.
During the analysis of mammograms two independent radiologists recorded breast arterial calcifications and based on their visual assessement classified them according to the degree of intensity in two stages:
1. First degree indicates gentle arterial calcifications
2. Second degree indicates intense arterial calcifications
In order to assess the presence and degree of stenosis duplex Doppler ultrasound with spectral flow quantification was done. The common carotid artery ( CCA) throughout the course , in the transverse and longitudinal sections was examined , then the bifurcation and the internal carotid artery (ICA) and external carotid artery (AC ). Stenoses were diagnosed by consensus on performing Doppler ultrasound adopted by a group of experts under the auspices of the Society of Radiologists in ultrasound in San Francisco ( USA ) in the year of 2002 .
Assessment of atherosclerotic lesions of the carotid arteries was performed in four stages:
O. level - normal Doppler ultrasound of the carotid arteries
1. degree - mild atherosclerotic changes in terms of wall thickening and ACI initial small plaque
2. degree - moderate atherosclerotic changes in terms of larger plaques and stenosis of up to 50 %
3. degree - advanced atherosclerotic changes in terms of stenosis over 50 %
All subjects underwent blood test analysis with attention to the risk factors for atherosclerosis ( triglycerides, cholesterol, glucose ) .
The results were statistically analyzed and presented numerically and in tables .
In this study, the average age of subjects was 61.95 ± 6.41 years , range 47-69 years. Groups of patients were compared by age and with regard to the result of mammography by age and the resulting variable whose averages are statistically significantly different in groups was based on statistical analysis. Insight into the mean age in groups, it is evident that there is a correlation between the findings of the age group of subjects with an intense calcification and atherosclerotic changes in the carotid artery ( F = 5.494 , p < .05 ) .
The above tabular and graphical data indicate a slight, statistically significant correlation between mammography findings with mild calcified arteries and changes in circulation disorder of the carotid arteries on Doppler test ( τ = ,149 , p < 0.05 ). With the increasing arterial calcification on mammography the result of Dopler test is increasing to some extent.
This connection is manifested in mild percent reduction proper findings and a slight increase of stenosis on Doppler test with increasing calcifications on mammography.
It can be determined that there is a statistically significant correlation between the results of intensive calcifications on mammography and the results of the Doppler test based on the data from the table and graphic display and the resulting chi-square test ( χ2 = 8.242 , p < 0.05 ). There is less proportion of patients with a normal Doppler and a greater proportion of those with stenosis ( especially stenoses < 50 % ) in the group with intense breast arterial calcifications.
In the research all respondents underwent blood tests with an analysis of known risk factors for cerebrovascular disease including: cholesterol, triglycerides and glucose .
The average blood glucose value was 6 ± 1.75 mmol / L , with a range from 4 to 25.95 mmol / L. The average amount of cholesterol in the blood was 5.37 ± 0.94 mmol / L , with a range from 3.94 to 8.8 mmol / L. The average value of triglycerides in the blood was 1.45 ± 0.5 mmol / L with a range of 0.74 to 4.23 mmol / L. There is no statistically significant correlation between breast arterial calcifications and these risk factors. History data related to cerebrovascular disease risk factors: smoking, alcohol consumption, data about previous use of oral contraceptives and taking hormone replacement therapy , hypertension , a prior morbidity from cardiovascular disease and peripheral arterial disease , BMI, atrial fibrillation were obtained from the respondents. Smoking is the only one variable of the three observed variables( smoking, hypertension, taking oral contraceptives) that is not allocated equally by both groups of respondents compared to mammography ( χ2 = 9.450 , p < 0.05 ) . In the group with gentle(mild) calcification is the highest proportion of smokers ( 28.9 %) compared to the group without calcification (14.6 %) or the group with intense calcification (12.1 %) .
It is evident that the index of smoking was 0.33, for alcohol consumption 0.006 and 0.33 for hypertension. Also low indices were for body mass index, hormone replacement therapy, atrial fibrillation, peripheral arterial disease and the number of births .
The results of this study confirmed a statistically high correlation between the intensive breast arterial calcifications and the presence of atherosclerotic changes in the carotid arteries. Mammographic finding of intense calcifications is a significant predictor of a positive result on Doppler or subjects with intense calcifications are 3,037 times more likely to have thickening of the carotid wall or stenosis. The results showed small statistically significant correlation with age and also with taking oral contraceptives. The probability of an increase in breast artery calcification slightly increases with age. Also, women taking oral contraceptives have a higher level of calcified breasts arteries
Correlation between breast arterial calcifications and atherosclerotic changes of carotid arteries
No full textCiljevi provedenog istraživanja bili su: istražiti povezanost kalcificiranih arterija dojki na mamogramu i njihovog stupnja, s aterosklerotskim promjenama i njihovim stupnjem u karotidnim arterijama, odrediti povezanost određenih rizičnih čimbenika: dob, pušenje, dijabetes, hipertenzija i hiperlipidemija, BMI, periferna arterijska bolest, fibrilacija atrija, oralni kontraceptivi, te prethodni CVI/TIA/RIND/ sa stupnjem kalcifikacija intramamarnih arterija na mamogramu, i dokazati značaj mamografskog nalaza kalcificiranih arterija dojki kao važnog pokazatelja za postojanje aterosklerotskih promjena karotidnih arterija, te tako pridonijeti ranom otkrivanju rizika za cerebrovaskularnu bolest.
U ovom istraživanju je uključeno 300 ispitanica koje su razvrstane u dvije skupine: ispitivana skupina sa 149 ispitanica s arterijskim kalcifikacijama dojki na mamogramu, i kontrolna skupina sa 151 ispitanicom bez arterijskih kalcifikacija dojki na mamogramu. U ispitivanoj grupi su dvije podgrupe ispitanica - ispitanice s nježnim i ispitanice s intenzivnim kalcifikacijama. Svim ispitanicama učinjen je Dopler karotida, uzeti su anamnestički podaci i učinjene su laboratorijske pretrage.
Istraživanje je, temeljem statističke obrade, pokazalo statistički značajnu povezanost kalcificiranih arterija dojki na mamografiji, i stupanj ateroskleroze karotidnih arterija na ultrazvučnom Dopler testu kod ispitivanih. Obradom je utvrđena statistički značajna povezanost nalaza srednje intezivnih kalcificiranih arterija dojki i uzimanja oralne kontracepcije, te dobi ispitanica. Statistički nema značajne povezanosti arterijskih kalcifikacija dojki s rizičnim čimbenicima u krvi (kolesterol, trigliceridi, glukoza), pušenjem, konzumacijom alkohola, kardiovaskularnim bolestima i BMI. Dobiveni rezultati ovog ispitivanja su potvrdili statistički visoku korelaciju između grupe intenzivnih kalcifikacija arterija dojki i postojanja aterosklerotskih promjena u karotidnim arterijama. Logističkom regresijom utvrđeno je da je nalaz intenzivnih kalcifikacija značajan prediktor pozitivnog rezultata na Dopleru.
Ispitivanjem je potvrđena hipoteza, da nazočnost kalcificiranih stijenki arterija dojke na mamografskom pregledu, upućuje na veću vjerojatnost aterosklerotičnih promjena stijenki karotidnih arterija. Mamografski nalaz kalcificiranih stijenki arterija dojki predstavlja povećan rizik za postojanje aterosklerotskih promjena karotidnih arterija, koje su značajan čimbenik rizika cerebrovaskularne bolesti.Cerebrovascular diseases in all its forms according to the frequency and the high percentage of lethality and mortality are at the very top of the problems of modern medicine. The goal of modern medical science is the prevention of cerebrovascular disease . In this research breast arterial calcifications in mammograms were detected predominantly within The National programme of early detection of breast cancer in Croatia which has been implemented in the Republic of Croatia since 2006. The aim of the research was to investigate a connection between calcified arteries on breast mammograms and atherosclerotic changes in the carotid arteries. The second objective was to determine the association of certain risk factors : age , smoking, diabetes, hypertension and hyperlipidemia, BMI, peripheral artery disease, atrial fibrillation, oral contraceptives and previous stroke /TIA/RIND/IM with the degree of intramammary arterial calcifications on mammograms. The study aimed to assess the importance of mammography findings of breast arterial calcifications (finding to which attention was not paid in everyday diagnosis ) as an important indicator for the presence of atherosclerotic changes in the carotid arteries, and thus contribute to the early detection of the risk for cerebrovascular disease. This was a prospective study that included 300 women aged 47-69 years. Breast arterial calcifications were found in mammograms of 149 women while the control group consisted of 151 women without breast arterial calcifications in mammograms .
The hypothesis of the study was :
1. Mammographic finding of breast arterial calcifications represents an increased risk for the existence of atherosclerotic changes of the carotid arteries, which are a significant risk factor for cerebrovascular disease.
2. The degree of breast arterial calcification is correlated with the degree of atherosclerotic changes in the carotid artery and carotid artery stenosis assessed by ultrasound.
3. The occurrence of breast arterial calcification is associated with age, smoking, elevated blood glucose, high blood pressure, lipids, BMI (body mass index ), peripheral artery disease , previous stroke / TIA / RIND / MI , atrial fibrillation , taking oral contraceptives, hormon replacement therapy .
All patients were included in mammography and Doppler ultrasound of carotid arteries with the risk factor anlaysis.
During the analysis of mammograms two independent radiologists recorded breast arterial calcifications and based on their visual assessement classified them according to the degree of intensity in two stages:
1. First degree indicates gentle arterial calcifications
2. Second degree indicates intense arterial calcifications
In order to assess the presence and degree of stenosis duplex Doppler ultrasound with spectral flow quantification was done. The common carotid artery ( CCA) throughout the course , in the transverse and longitudinal sections was examined , then the bifurcation and the internal carotid artery (ICA) and external carotid artery (AC ). Stenoses were diagnosed by consensus on performing Doppler ultrasound adopted by a group of experts under the auspices of the Society of Radiologists in ultrasound in San Francisco ( USA ) in the year of 2002 .
Assessment of atherosclerotic lesions of the carotid arteries was performed in four stages:
O. level - normal Doppler ultrasound of the carotid arteries
1. degree - mild atherosclerotic changes in terms of wall thickening and ACI initial small plaque
2. degree - moderate atherosclerotic changes in terms of larger plaques and stenosis of up to 50 %
3. degree - advanced atherosclerotic changes in terms of stenosis over 50 %
All subjects underwent blood test analysis with attention to the risk factors for atherosclerosis ( triglycerides, cholesterol, glucose ) .
The results were statistically analyzed and presented numerically and in tables .
In this study, the average age of subjects was 61.95 ± 6.41 years , range 47-69 years. Groups of patients were compared by age and with regard to the result of mammography by age and the resulting variable whose averages are statistically significantly different in groups was based on statistical analysis. Insight into the mean age in groups, it is evident that there is a correlation between the findings of the age group of subjects with an intense calcification and atherosclerotic changes in the carotid artery ( F = 5.494 , p < .05 ) .
The above tabular and graphical data indicate a slight, statistically significant correlation between mammography findings with mild calcified arteries and changes in circulation disorder of the carotid arteries on Doppler test ( τ = ,149 , p < 0.05 ). With the increasing arterial calcification on mammography the result of Dopler test is increasing to some extent.
This connection is manifested in mild percent reduction proper findings and a slight increase of stenosis on Doppler test with increasing calcifications on mammography.
It can be determined that there is a statistically significant correlation between the results of intensive calcifications on mammography and the results of the Doppler test based on the data from the table and graphic display and the resulting chi-square test ( χ2 = 8.242 , p < 0.05 ). There is less proportion of patients with a normal Doppler and a greater proportion of those with stenosis ( especially stenoses < 50 % ) in the group with intense breast arterial calcifications.
In the research all respondents underwent blood tests with an analysis of known risk factors for cerebrovascular disease including: cholesterol, triglycerides and glucose .
The average blood glucose value was 6 ± 1.75 mmol / L , with a range from 4 to 25.95 mmol / L. The average amount of cholesterol in the blood was 5.37 ± 0.94 mmol / L , with a range from 3.94 to 8.8 mmol / L. The average value of triglycerides in the blood was 1.45 ± 0.5 mmol / L with a range of 0.74 to 4.23 mmol / L. There is no statistically significant correlation between breast arterial calcifications and these risk factors. History data related to cerebrovascular disease risk factors: smoking, alcohol consumption, data about previous use of oral contraceptives and taking hormone replacement therapy , hypertension , a prior morbidity from cardiovascular disease and peripheral arterial disease , BMI, atrial fibrillation were obtained from the respondents. Smoking is the only one variable of the three observed variables( smoking, hypertension, taking oral contraceptives) that is not allocated equally by both groups of respondents compared to mammography ( χ2 = 9.450 , p < 0.05 ) . In the group with gentle(mild) calcification is the highest proportion of smokers ( 28.9 %) compared to the group without calcification (14.6 %) or the group with intense calcification (12.1 %) .
It is evident that the index of smoking was 0.33, for alcohol consumption 0.006 and 0.33 for hypertension. Also low indices were for body mass index, hormone replacement therapy, atrial fibrillation, peripheral arterial disease and the number of births .
The results of this study confirmed a statistically high correlation between the intensive breast arterial calcifications and the presence of atherosclerotic changes in the carotid arteries. Mammographic finding of intense calcifications is a significant predictor of a positive result on Doppler or subjects with intense calcifications are 3,037 times more likely to have thickening of the carotid wall or stenosis. The results showed small statistically significant correlation with age and also with taking oral contraceptives. The probability of an increase in breast artery calcification slightly increases with age. Also, women taking oral contraceptives have a higher level of calcified breasts arteries
- …
