Branislav Petrovic

Characteristics of upper urothelial carcinoma in an area of Balkan endemic nephropathy in south Serbia. A fifty-year retrospective study.

Aims and background Upper urinary tract transitional cell carcinoma, a relatively rare tumor, is up to 100 times more frequent in regions with Balkan endemic nephropathy. Characteristics of transitional cell carcinoma in the endemic South Morava Region in Serbia in the previous 50 years were evaluated. Patients We analyzed 477 cases with pathologically confirmed transitional cell carcinoma who underwent surgery from 1957 to 2006: 91 from endemic, 106 from adjacent and 280 from control settlements. Cases in the study came from 10 endemic villages, 46 adjacent villages, 51 control villages and the city of Nis. Results The increase in number of transitional cell carcinoma from 1957 was followed by a peak between 1967 and 1978 (yearly incidence 21.9 per 100,000) and a slow decrease thereafter to 7.4 (1997–2006). In the control settlements, the increase was steady. Reduced kidney function at surgery was found in 58% of patients from endemic and in 20% from control settlements. Age at surgery has significantly increased from 52.3 and 51.5 (1957–1966) to 70.9 and 66.1 (1997–2006) for endemic and control settlements, respectively. The female sex was predominant in endemic and adjacent settlements and the male sex in control settlements. Transitional cell carcinoma from endemic settlements was of a lower grade in the period from 1957–1986, but in the period from 1987–2006 they were predominantly high grade. Low tumor stage (pTa-pT1) predominated in transitional cell carcinoma from the endemic and adjacent but not the control settlements in the period from 1957 to 1986. However, in the last 20 years, upper urinary tract transitional cell carcinoma stage increased, the highest in the period from 1997 to 2006 in all settlements studied. Conservative surgery was advocated for transitional cell carcinoma in Balkan endemic nephropathy areas up to 1996. Transitional cell carcinoma are now more malignant and more advanced than before, and a less aggressive approach is used only for absolute indications. Conclusions An increased number of transitional cell carcinoma in endemic settlements was observed, markedly decreasing in the last decade. An increasing age and a shorter survival were recorded in patients both from Balkan endemic nephropathy and control settlements. Sporadic cases upper urinary tract transitional cell carcinoma in settlements adjacent to endemic settlements were demonstrated. Free full text available at www.tumorionline.it

Health-related quality of life in patients after the acute myocardial infarction

IntroductionAcute myocardial infarction has a negative impact on patient’s quality of life. The aim of this paper was to evaluate the health-related quality of life in patients one month after the acute myocardial infarction.Material and methodThe study involved 160 patients of both sexes, 30 to 79 years of age. The health-related quality of life in patients was assessed at the admission at the coronary care unit, and one month after. The following questionnaires were used: EuroQuolVAS and EuroQuol 5 Dimension. Angina pectoris was ranked according to the Canadian Cardiovascular Society Classification. Results: Men and women evaluated their health condition in a similar way (60.48±11.98 vs 60.55±12.24). Patients who (have) undergone primary coronary intervention had significantly higher average scores on EuroQuolVAS than the patients who were treated with thrombolytic therapy (68.69±9.67 vs 52.31±7.87, p<0.001). Modest and severe problems were the most presented in answers to those questions: pain/discomfort, anxiety/depression and self-care. Both men (0.92±0.43 vs 3.27±0.59, p<0.001) and women (0.89±0.46 vs 3.19±0.55, p<0.001) had significiantly lower average marks of angina pectoris one month after the acute myocardial infarction than at the admission to the hospital.ConclusionOne month after the acute myocardial infarction the quality of life in patients was very impared. Patients who undergone to the primary coronary intervention evaluated their health condition as better than the patients who were treated with thrombolytic therapy. Those patients also had the lower average marks of angina pectoris and the higher health-related quality of life.

THE INFLUENCE OF MARITAL STATUS ON EPIDEMIOLOGICAL CHARACTERISTICS OF SUICIDES IN THE SOUTHEASTERN PART OF SERBIA

BACKGROUND The support of close persons is a protective factor in the suicide epidemiology. The aim of this paper is to determine if there are differences between epidemiological characteristics of the suicides committed by married people in relation to singles. METHODS In order to determine epidemiological characteristics of suicide among married and single people in the southeastern Serbia 628 suicides committed from 1995 to 2002 among persons 20 years of age and over were analysed. To compare suicide rates between married and single persons chi2 test was performed. RESULTS From 628 registered suicides, 188 were performed by women, and 440 by men. The average annual suicide rate among males was 24.1 per 100,000 and among females it was 9.9. The highest rates were among widowed (139.0) and divorced men (63.2). The highest risk factor for suicide was to be widowed (men: RR=8.35; women: RR=2.75). The suicide trend among women, both married and single has been declining, whilst among males it has been on significant increase. Seasonality of suicides, weekly and daily distribution had a small influence on the epidemiological characteristics of suicides. Married women committed more suicides by poisoning than single women (p=0.02). In both groups, the most frequent way is hanging. CONCLUSION Though marital status plays important role in an increasing rates of suicide, time and the way of its happening, this role is not decisive. Single people are very vulnerable and the time and way of suicide show that their reasons are more serious than among married ones.

Multi-channel Media Access Control for Wireless Sensor Networks: A survey

This paper deals with multi-channel Media Access Control (MAC) protocols for Wireless Sensor Networks (WSNs). We first give an overview of multi-channel communication in WSNs and propose the classification of existing multi-channel MAC protocols for WSNs. Then, we describe briefly three representative protocols by stating their essential behavior and emphasizing their strengths and weaknesses.

[Association of stressful life events with acute myocardial infarction in population in the city of Nis within the period from 1998-2000].

BACKGROUND/AIM Stressful life events present a very important category of psychosocial stress. A few studies have showed that a psychosocial stress represents a very important risk factor for acute myocardial infarction (AMI), but measures of stress may not be suitable for different countries, cultures and ethnic groups. The aim of this study was to investigate the relation of stressful life events with AMI in the period of 1998-2000 in the population of the city of Nis. METHODS A case-control study included 100 patients with the first MI (in the period 1998-2000) and 100 healthy subjects, matched with respect to sex and age (+/- 2 years) from the city of Nis. The data of stressful life events were obtained by the Scaling of life events by Paykel ES, modified by the authors consistent with the examined population and the period of investigation. The Yates chi2 test, odds ratio - OR and their 99% interval of confidence were used as statistical procedures. RESULTS The results showed that stressful life events in the period of investigation were very important risk factors for AMI with a statistically significant level (p = 0.000). Huge financial problems (OR = 202.36, Ci = 24.82-4387.58), violation of law (OR = 168.00, Ci = 10.66-6658.96) and serious illness of family members (OR = 159.60, Ci = 19.05- 3514.81) were the highest risk for AMI. The patients who reported that his/her son or other member of family had been gone to the army (or mobilization) before the illness onset, had 138 times higher risk of AMI (Ci = 14.98-3222.47, chi2 = 40.95, p = 0.000), while the patients who had mobilized themselves had 84 times higher risk (Ci = 7.00-2363.06, chi2= 23.87, p = 0.000). Effect of several stressful life events lead to significantly increased risk of AMI andthat significance is larger as the number of life events is more frequent (one life event: OR = 28.41, Ci = 3.73-593.52; chi2 = 17.40, p = 0.000; ? 4: OR = 336.00, Ci = 28.31-9760.28, chi2 = 50,43, p = 0,000). CONCLUSION These findings indicate that stressful life events are associated with AMI and that they are very important for further epidemiological investigation of the triggering mechanisms and should improve preventive strategies of this serious disorder.

Reliable data transfer Rendezvous protocol in wireless sensor networks using 2D-SEC-DED encoding technique

Abstract Many applications in Wireless Sensor Networks (WSNs) require all data to be transmitted with minimal or without loss, what implies that reliability is an important characteristic. In any WSN, there are two basic approaches to recover erroneous packets. One way is to use Automatic Repeat reQuest (ARQ), and another is Forward Error Correction (FEC). The error-control systems for applications based on ARQ use error detection coupled with retransmission requests to maximize reliability at some cost to throughput. Error detection is generally provided by the lower protocol layers which use checksums (e.g. Cyclic Redundancy Checksums (CRCs)) to discard corrupted packets and trigger retransmission requests. In these solutions event a single erroneous bit can render a packet useless to the end user. Having in mind that in WSNs the power is scarce and is primarily consumed by wireless transmission and reception, we propose to use FEC rather than ARQ. FEC is a way of correcting packets by transmitting additional information bits with aim to reduce the frequency of retransmission requests. During this, data bytes are optionally encoded after being fragmented with Error Correcting Code (ECC) to recover data bits in case of small number of bit errors. Various FEC encoding schemes such as erasure and Hamming based codes are available. The choice of the encoding schemes depends on the applications and error characteristics (error models/patterns) of the wireless channel. Erasure encoding is preferable for usage when the error pattern is burst dominated, while Hamming encoding when noise causes random errors. Our observations show that most bit errors are single-bit or double-bit errors and burst errors are present but rare. In this work, an efficient Hamming based FEC encoding scheme of relatively low complexity called Two Dimensional-Single Error Correcting-Double Error Detecting (2D-SEC-DED), intended to minimize packet retransmissions and to save energy, has been developed. Such FEC scheme can be used to correct all single-bit and 99.99%of double/multiple-bit errors. Since the radio block is dominant energy consumer within a Sensor Node (SN), we focus our attention to answer the question: which is the adequate metric to use, and under what conditions to accurately characterize the quality of the communication, related to reliable data transfer, with minimal energy consumption. To this end, as first, in a case when the bit error is not high and most errors are single-bit, we show that 2D SEC-DED encoding scheme is more energy efficient in comparison to erasure encoding. As second, the advantages of using 2D-SEC-DED in respect to CRC (NO-FEC) encoding, concerning decreasing the energy consumption and increasing the reliability of the radio block are derived through implementation of two versions of the Rendezvous Protocol for Long Living (RPLL) referred as Modified-RPLL (M-RPLL as FEC based) and Ordinary-RPLL (O-RPLL as NO-FEC), respectively.

Attitudes and Knowledge of Medical Students about Distance Learning / Stavovi i znanje studenata medicine o učenju na daljinu

Abstract Distance learning can be defined as education or training offered to participants at a different place, physically distant from the lecturer or sources of information. The difference in attitudes and knowledge of students about distance learning in relation to gender and year of studying was examined. The study sample included 371 students of the Faculty of Medicine in Niš (165 students were at the first year of studies and 206 students were at the sixth year of studies). Originally structured epidemiological questionnaire was distributed to students. Gender and age had no significant influence on students’ knowledge of distance learning. There was no statistically significant difference in taking positive attitudes about distance learning among medical students of the first and sixth year. Gender has statistically significantly affected the attitudes. E-learning does not eliminate the existing methods of learning, but it supplements them and greatly helps in teaching plans and programs. Sažetak Učenje na daljinu se može definisati kao obrazovanje ili obuka koja se nudi polaznicima na različitom mestu odnosno fizički udaljenim od predavača ili izvora informacija. Cilj rada je bio analiza stavova i znanja o učenju na daljinu studenata medicine, kao i utvrđivanje uticaja pola i starosnog doba na zauzumanje odredenog stava i znanja. Uzorak istraživanja je obuhvatio 371 studenata Medicinskog fakulteta u Nišu (165 studenata na prvoj godini studija i 206 studenata na sestoj godini studija). Studentima je podeljen originalni epidemioloski upitnik. Starosna dob i polna pripadnost nisu imale statisticki znacajan uticaj na znanja o ucenju na daljinu. Nije nađena statistička značajnost razlika u zauzimanju pozitivnih stavova o učenju na daljinu među studenatima medicine prve i seste godine studija. Polna pripadnost je statisticki znacajno uticala na zauzimanje određenog stava. E-učenje ne eliminiše postojeće metode učenja, već ih samo upotpunjuje i u mnogome pomaže u savlađivanju nastavnih planova i progarama.

Using adaptive filtering in single-phase grid-connected system

Recently, there has been a pronounced increase of interest in the field of renewable energy. In this area power inverters are crucial building blocks in a segment of energy converters, since they change direct current (DC) to alternating current (AC). Grid connected power inverters should operate in synchronism with the grid voltage. In this paper, the structure of a power system based on adaptive filtering is described. The main purpose of the adaptive filter is to adapt the output signal of the inverter to the corresponding load and/or grid signal. By involving adaptive filtering the response time decreases and quality of power delivery to the load or grid increases. A comparative analysis which relates to power system operation without and with adaptive filtering is given. In addition, the impact of variable impedance of load on quality of delivered power is considered. Results which relates to total harmonic distortion (THD) factor are obtained by Matlab/Simulink software.

One Realization of Low-Power Wireless Sensor Node

In this paper a practical realization of sensor node is described. Performance analysis for new implemented protocol is also described. In proposed model a sensor network is organized into local clusters. Within the cluster a nodes are battery powered and fixed cluster-head or gateway node have large power supply. In this paper a data exchange between sensor node and cluster head only bee analyzed. Data exchange and number of nodes in cluster is effect statistical analysis based upon in Poisson distribution. Minimum number of trials needed to be sure that the packet reaches the receiver with prescribed probability for varying bit error rate is discussed, too. Lastly, for our hardware solution and example application for temperature measurement energy consumption analysis is given. Comparative results display a power consumption reduction of one order of magnitude regard to previous solution.

TV link receiver unit realization

In this paper, one practical realization of indoor unit of TV link receiver is described. Receiver unit is part of microwave radio relay system in 10GHz range. Unit is capable for receiving and demodulating FM signals in baseband of up to 10 MHz. Baseband is divided in two parts. First (0 to 5 MHz) is reserved for video signal, and second (5 MHz to 10 MHz) is for two audio subcarriers. Realization is based on satellite receiver in-door unit structure. It include Samsung BS-Tuner, integrated circuit SGS Thompson STV0042 for video processing and microcontroller unit based on Atmels AT89C2051.