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Dive into the research topics where Nataša Kejžar is active.

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Featured researches published by Nataša Kejžar.


Resuscitation | 2015

Frequency and number of resuscitation related rib and sternum fractures are higher than generally considered

Eduard Kralj; Matej Podbregar; Nataša Kejžar; Jože Balažic

AIM OF THE STUDY This study aimed to establish the incidence, number and location of CPR-related skeletal chest injuries (SCI) and to investigate the influence of age, gender, changes in resuscitation guidelines and technique of resuscitation. METHODS We analysed SCI in 2148 patients who had undergone resuscitation for non-traumatic cardiac arrest, as shown by autopsies performed at the Institute of Forensic Medicine in Ljubljana in the period 2004-2013. RESULTS External cardiac massage caused SCI in 86% of males and in 91% of females; sternum fractures occurred in 59% of males and 79% of females, rib fractures in 77% of males and 85% of females and sternocostal separations in 33% of males and 12% of females. The average number of all SCI per person was thus almost the same in males and females: 10.95 vs. 10.96. The percentage of patients injured and the number of SCI increased with age. Changes in resuscitation guidelines were also identified as a factor contributing to the incidence and number of SCI. No adverse effect of the use of LUCAS was found. CONCLUSION It is generally considered that at least 1/3 of resuscitated patients sustain rib fractures and at least 1/5 sustains sternum fractures. However, our study showed that these injuries are much more frequent and that increased compression rate and depth cause more SCI. Since in the period 2011-2013 accompanying severe injuries occurred in only 1.85% of cases, the resuscitation technique has not yet jeopardised patients safety, but further close monitoring is needed.


Archive | 2010

Network Analysis of Works on Clustering and Classification from Web of Science

Nataša Kejžar; Simona Korenjak Černe; Vladimir Batagelj

Web of Science (WoS) is a database that provides information about current and past articles published in over 10,000 of the most prestigious, high impact research journals in the world from year 1970 on. A file with full information – records about selected articles – can be downloaded and further analyzed. We collected from WoS complete records on articles from Journal of Classification, articles citing these articles, and articles in WoS cited by them at least 10 times. A special program WoS2Pajek was developed for converting such data into Pajek network files. The citation network between articles, networks of articles ×authors, articles × keywords, articles × journals, and the partition according to publication year were obtained from the data. These networks were analyzed in order to identify the most important authors, works and topics that have been involved in the field in the last decades.


Journal of Mathematical Sociology | 2008

Probabilistic inductive classes of graphs

Nataša Kejžar; Zoran Nikoloski; Vladimir Batagelj

A unifying framework—probabilistic inductive classes of graphs (PICGs)—is defined by imposing a probability space on the rules and their left elements from the standard notion of inductive class of graphs. The rules can model the processes creating real-world social networks, such as spread of knowledge, dynamics of acquaintanceships or sexual contacts, and emergence of clusters. We demonstrate the characteristics of PICGs by casting some well-known models of growing networks in this framework. Results regarding expected size and order are derived. For PICG models of connected and 2-connected graphs order, size and asymptotic degree distribution are presented. The approaches used represent analytic alternative to computer simulation, which is mostly used to obtain the properties of evolving graphs.


Data Science and Classification | 2006

Analyzing the Structure of U.S. Patents Network

Vladimir Batagelj; Nataša Kejžar; Simona Korenjak-Černe; Matjaž Zaveršnik

The U.S. patents network is a network of almost 3.8 millions patents (network vertices) from the year 1963 to 1999 (Hall et al. (2001)) and more than 16.5 millions citations (network arcs). It is an example of a very large citation network.


Population Studies-a Journal of Demography | 2015

A weighted clustering of population pyramids for the world's countries, 1996, 2001, 2006

Simona Korenjak-Černe; Nataša Kejžar; Vladimir Batagelj

This paper presents clusters of the worlds countries obtained by a novel weighted clustering method. The approach is based on data representations with symbolic descriptions of age–sex structures. To obtain clusters with similar descriptions, a weighted clustering method is used which is suitable for data described with discrete distributions. In contrast to the classical approach, this method allows the population of each sex to be included in the clustering process, thereby obtaining a representative age–sex structure corresponding to all the countries contained in the cluster. Observing the data over time reveals clusters of countries with similar changes in their population age–sex distributions. The resulting population pyramids are presented for 1996, 2001, and 2006. An online supplement to this paper is available at http://dx.doi.org/10.1080/00324728.2014.954597.


Journal of Classification | 2011

Clustering of Distributions: A Case of Patent Citations

Nataša Kejžar; Simona Korenjak-Černe; Vladimir Batagelj

Often the data units are described with discrete distributions (work described with citation distribution over time, population pyramid described as age-sex distribution etc.).When the set of such units is very large, appropriate clustering methods can reveal the typical patterns hidden in the data.In this paper we present an adapted leaders method combined with a compatible adapted agglomerative hierarchical method that are based on relative error measure between a unit and the corresponding cluster representative–leader. The proposed approach is illustrated on citation distributions derived from the data set of US patents from 1980 to 1999. These new methods were developed because clustering of units, described with distributions, with classical k-means method reveals patterns with single high peaks which correspond to a single year. These patterns prevail over other distribution shapes also present in the data. Compared with centers in k-means method, clusters’ representatives obtained with the proposed new methods better detect typical distribution shapes of units. The obtained main cluster types for different sets of units show three main patterns: patents with early or late peak of importance to the community, and patents where the importance is slowly increasing throughout the time period.


Journal of Informetrics | 2014

On standardization of the Activity Index

Janez Stare; Nataša Kejžar

Relative Specialization Index (RSI) was introduced as a simple transformation of the Activity Index (AI), the aim of this transformation being standardization of AI, and therefore more straightforward interpretation. RSI is believed to have values between −1 and 1, with −1 meaning no activity of the country (institution) in a certain scientific field, and 1 meaning that the country is only active in the given field. While it is obvious from the definition of RSI that it can never be 1, it is less obvious, and essentially unknown, that its upper limit can be quite far from 1, depending on the scientific field. This is a consequence of the fact that AI has different upper limits for different scientific fields. This means that comparisons of RSIs, or AIs, across fields can be misleading. We therefore believe that RSI should not be used at all. We also show how an appropriate standardization of AI can be achieved.


PLOS ONE | 2018

Sequential assessment of clinical and laboratory parameters in patients with hemorrhagic fever with renal syndrome

Emil Pal; Miša Korva; Katarina Resman Rus; Nataša Kejžar; Petra Bogovič; Anica Kurent; Tatjana Avšič-Županc; Franc Strle

Background Information on the sequential appearance, duration, and magnitude of clinical and laboratory parameters in hemorrhagic fever with renal syndrome (HFRS) is limited. Methods Analysis of clinical and laboratory parameters obtained serially in 81 patients with HFRS, of whom 15 were infected with Dobrava virus and 66 with Puumala virus. Results The initial signs/symptoms, appearing on median day 1 of illness, were fever, headache, and myalgia. These were present in 86%, 65%, and 40% of patients and had a median duration of 4, 4, and 5.5 days, respectively. The signs/symptoms were followed by myopia (appearance on day 5), insomnia (day 6), oliguria/anuria (day 6), polyuria (day 9), and sinus bradycardia (day 9.5). These were present in 35%, 30%, 28%, 91%, and 35% of patients; their median duration was 2, 2, 2, 7, and 1 day, respectively. Laboratory abnormalities, including thrombocytopenia, elevated alanine aminotransferase, CRP, procalcitonin, creatinine, diminished glomerular filtration rate, and leukocytosis, were ascertained on admission to hospital or on the following day (day 5 or 6 of illness) and were established in 95%, 87%, 99%, 91%, 94%, 87%, and 55% of patients, and had a median duration of 4, 3, 7, 3, 9, 8, and 2 days, respectively. Comparison of patients infected with Dobrava and Puumala viruses found several differences in the frequency, magnitude, and duration of abnormalities, indicating that Dobrava virus causes the more severe HFRS. Conclusions In the majority of patients, the classic clinical distinction into febrile, hypotonic, oliguric, polyuric, and convalescent phases of illness is unclear.


Emerging microbes & infections | 2018

Relationship between circulating vascular endothelial growth factor and its soluble receptor in patients with hemorrhagic fever with renal syndrome

Emil Pal; Miša Korva; Katarina Resman Rus; Nataša Kejžar; Petra Bogovič; Franc Strle; Tatjana Avšič-Županc

Hemorrhagic fever with renal syndrome (HFRS) is characterized by endothelial dysfunction with capillary leakage without obvious cytopathology in the capillary endothelium. The aim of the study was to analyze the kinetics of vascular endothelial growth factor (VEGF) and its soluble receptor (sVEGFR-2) in HFRS patients infected with Dobrava (DOBV) or Puumala virus (PUUV). VEGF and sVEGFR-2 levels were measured in daily plasma and urine samples of 73 patients with HFRS (58 with PUUV, 15 with DOBV) and evaluated in relation to clinical and laboratory variables. In comparison with the healthy controls, initial samples (obtained in the first week of illness) from patients with HFRS had higher plasma and urine VEGF levels, whereas sVEGFR-2 levels were lower in plasma but higher in urine. VEGF levels did not differ in relation to hantavirus species, viral load, or the severity of HFRS. The comparison of VEGF dynamics in plasma and urine showed the pronounced secretion of VEGF in urine. Significant correlations were found between daily VEGF/sVEGFR-2 levels and platelet counts, as well as with diuresis: the correlations were positive for plasma VEGF/sVEGFR-2 levels and negative for urine levels. In addition, patients with hemorrhagic manifestations had very high plasma and urine VEGF, together with high urine sVEGFR-2. Measuring the local secretion of sVEGFR-2 in urine might be a useful biomarker for identifying HFRS patients who will progress to severe disease.


Archive | 2014

Understanding large temporal networks and spatial networks : exploration, pattern searching, visualization and network evolution

Vladimir Batagelj; Patrick Doreian; Anuška Ferligoj; Nataša Kejžar

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Franc Strle

University of Ljubljana

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Janez Stare

University of Ljubljana

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Miša Korva

University of Ljubljana

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Eduard Kralj

University of Ljubljana

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