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Search Results: 1 - 10 of 464270 matches for " ?or?evi? Sini?a "
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The Aubry-Mather theorem for driven generalized elastic chains
Sinia Slijep?evi
Mathematics , 2013,
Abstract: We consider uniformly (DC) or periodically (AC) driven generalized infinite elastic chains (a generalized Frenkel-Kontorova model) with gradient dynamics. We first show that the union of supports of all the invariant measures, denoted by A, projects injectively to a dynamical system on a 2-dimensional cylinder. We also prove existence of ergodic invariant measures supported on a set of rotationaly ordered configurations with an arbitrary (rational or irrational) rotation number. This shows that the Aubry-Mather structure of ground states persists if an arbitrary AC or DC force is applied. The set A attracts almost surely (in probability) configurations with bounded spacing. In the DC case, the set A consists entirely of equilibria and uniformly sliding solutions. The key tool is a new weak Lyapunov function on the space of translationally invariant probability measures on the state space, which counts intersections.
Alkaloids in the pharmaceutical industry: Structure, isolation and application
Nikoli? Milan,?or?eviSinia M.
Hemijska Industrija , 2003, DOI: 10.2298/hemind0310471n
Abstract: By the end of the 18th and the beginning of the 19th century a new era began in medicine, pharmaceutics and chemistry that was strongly connected with alkaloids and alkaloid drugs. Even before that it was known that certain drugs administered in limited doses were medicines, and toxic if taken in larger doses (opium, coke leaves, belladonna roots, monkshood tubers crocus or hemlock seeds). However, the identification, isolation and structural characterization of the active ingredients of the alkaloid drugs was only possible in the mid 20th century by the use of modern extraction equipment and instrumental methods (NMR, X-ray diffraction and others).In spite of continuing use over a long time, there is still great interest in investigating new drugs, potential raw materials for the pharmaceutical industry, as well as the more detailed investigation and definition of bio-active components and the indication of their activity range, and the partial synthesis of new alkaloid molecules based on natural alkaloids. The scope of these investigations, especially in the field of semi-synthesis is to make better use of the bio-active ingredients of alkaloid drugs, i.e. to improve the pharmacological effect (stronger and prolonged effect of the medicine, decreased toxicity and side effects), or to extend or change the applications. A combined classification of alkaloids was used, based on the chemical structure and origin, i.e. the source of their isolation to study alkaloid structure. For practical reasons, the following classification of alkaloids was used: ergot alkaloids, poppy alkaloids, tropanic alkaloids purine derivative alkaloids, carbon-cyclic alkaloids, and other alkaloids. The second part of this report presents a table of general procedures for alkaloid isolation from plant drugs (extraction by water non-miscible solvents, extraction by water-miscible solvents and extraction by diluted acid solutions). Also, methods for obtaining chelidonine and glaucine as hydrochloride bases and salts were presented in more details. Data from leading world pharmacopoeias (Ph. Eur. Ill/s 2000, DAB 1996, USP 23, JP XIII, BP 1993, Ph. Jug. IV) were used in the study of application of the pure alkaloids in pharmaceutical forms with predetermined doses. A comparative study of these data shows that a great number of preparations are produced worldwide based on alkaloids and alkaloids with modified structure. These medicines have found use in modern therapeutic practice in many countries. Most products are produced on the basis of caffeine, theophylline, ephedrine, atropine
Influence of different types of surgical suture materials on mehanical damage of oral mucosa
Mirkovi? Sinia,?ur?evi?-Mirkovi? Tatjana
Medicinski Pregled , 2011, DOI: 10.2298/mpns1104157m
Abstract: Introduction. Throughout history many kinds of different suture materials have been used for closing and suturing surgical wounds. Medical literature describes four basic characteristics of suture material: knot safety, tensile strength, tissue reaction and wound safety. The tissue reaction is reflected in an inflammatory response, which, though minimal, occurs during first two to seven days after implanting suture into the tissue. The aim of this research was to investigate whether different suture materials affect the development of decubital damage of oral mucosa, which to a great extent can compromise the process of wound healing. Material and methods. The investigation was designed as a prospective clinical study including 150 patients of both genders, aged between 25 and 60. The patients were distributed into three groups of 50 persons. The suture Black Silk was used in the first group, designated as a control group. Nylon and Vicril were used in the second and third group, i.e. experimental groups, respectively. Decubital damage of the surrounding soft tissues was the main parameter for monitoring the effects of selected suture materials on the oral mucosa. Conclusion. The comparison of results obtained for the investigated suture materials after suturing oral mucosa revealed that certain advan-tage could be given to synthetic monofilament suture materials
The transport speed and optimal work in pulsating Frenkel-Kontorova models
Braslav Rabar,Sinia Slijep?evi
Mathematics , 2015,
Abstract: We consider a generalized one-dimensional chain in a periodic potential (the Frenkel-Kontorova model), with dissipative, pulsating (or ratchet) dynamics as a model of transport when the average force on the system is zero. We find lower bounds on the transport speed under mild assumptions on the asymmetricity and steepness of the site potential. Physically relevant applications include explicit estimates of the pulse frequencies and mean spacings for which the transport is non-zero, and more specifically the pulse frequencies which maximize work. The bounds explicitly depend on the pulse period and subtle number-theoretical properties of the mean spacing. The used method is a study of the time evolution of spatially invariant measures in the space of measures equipped with the $L^1$-Wasserstein metric. Even though it is applied here in a deterministic setting, thus could perhaps also be of use for ratchet models in random fields.
Patient’s Comfort and Technical Quality Exams at 1.5 and 3.0 T Magnetic Resonance Imaging  [PDF]
Sinia Vujmilovi?, Sa?a Vujnovi?, Violeta Kova?evi?-Dragosavljevi?, Zoran Vujkovi?, Davorka Katana, Dragana Gruji?-Vujmilovi?
Open Journal of Radiology (OJRad) , 2016, DOI: 10.4236/ojrad.2016.64035
Abstract: Increased interest of clinicians for using 3.0 T magnetic resonance imaging (MRI), as imaging modality of choice for their patients, has been evident in the past few years. The aim of this study was to compare the technical quality of the obtained tomography using 3.0 T and 1.5 T MRI, and to compare the subjective feeling of discomfort of patients and subjective acoustic noise experience during imaging using MRI at 3.0 T and 1.5 T. Brain MRI (1.5 and 3.0 T) was performed in 58 patients, according to a standardized protocol. All studies have been randomly described by independent two radiologists. The reference standard for the existence of technical artifact is established on the basis of both radiologists’ consensus. We also compared the subjective feelings of the discomfort and acoustic noise during the both MRI (1.5 T and 3.0 T) exams. Artifacts were significantly more common during 3.0 T MRI in comparison with the 1.5 T MRI (χ2 = 5.286, P < 0.05), as well as in male patients (χ2 = 8.841, P < 0.05), and sub-jective assessments of discomfort and acoustic noise were higher in patients who underwent imaging using 3.0 T MRI, (χ2 = 125.959, df = 1, P < 0.001) and in females (χ2 = 195.449, df = 1, P < 0.001). Additional research is needed to prove that appropriate information for patients about the discomfort during 3.0 T MRI and their psychological preparation is very important element for optimal use of 3.0 T MRI in daily clinical practice.
Effect of planting density on diameter structure of black poplar clones S6-7 and M-1 - section Aigeiros [Duby]
Andra?ev Sinia,Ron?evi? Savo,Bobinac Martin T.
Glasnik ?umarskog Fakulteta , 2003, DOI: 10.2298/gsf0388007a
Abstract: The parameters of diameter structure of two black poplar clones in the section Aigeiros Duby (S6-7 and M-1) are presented depending on three different spacings: 3x3 m, 4.25x4.25 m and 6x6 m. Modeling of diameter structure was performed by Weibull’s function of probability distribution. We determined the effect of spacing (density) and clone both on the parameters and on the model diameter structure.
Hyperkalemia in hypertensive patients undergoing regular hemodialysis during enalapril and fosinopril therapy
Dimkovi? Nada,?or?evi? Tanja,Popovi? Jovan,Dimkovi? Sinia
Srpski Arhiv za Celokupno Lekarstvo , 2006, DOI: 10.2298/sarh0602044d
Abstract: Introduction. Hypertension is evident in 80%-85% of patients with chronic renal failure and antihypertensive therapy is needed in 25%-30% of patients. Apart from antihypertensive effect, ACEi’s decrease the left ventricular hypertrophy and mortality in dialysis patients. Even so, their use is limited due to hyperkalemia. Objective. The objective of the study was to compare the effect of fosinopril and enalapril on serum potassium level in hypertensive hemodialysis patients. Method. Prospective pilot study included 16 patients undergoing chronic hemodialysis, with mean age of 58.9±9.6 years and mean duration of hypertension 11.3±7.1 years. The effect of antihypertensive drugs of equivalent dose was followed during three periods (three months each): period 1 (therapy with enalapril), period 2 (therapy with fosinopril) and period 3 (therapy with enalapril). Dialysis conditions were constant and patients were without signs of catabolic state. Laboratory results were followed on monthly basis and mean values were compared by ANOVA-one way test. Difference between variables between periods was tested using Bonferoni method. Results. There was significant difference between mean serum potassium levels throughout three therapeutic periods (5.88±0.38 vs. 4.99±0.44 vs. 5.46±0.46mmol/l; p<0.001). Difference was evident even in the first month of fosinopril therapy. The effect can not be explained by dialysis adequacy since Kt/ V was similar throughout three treatment periods (1.18±0.24 vs. 1.25±0.21 vs. 1.25±0.14; p=ns). Systolic blood pressure was regulated even better with fosinopril than with enalapril (187.5±21.4 mmHg vs.160.0±20.0 mmHg; p=0.01) and this effect was prolonged during period 3 (160.0±26.1mmHg). Hemoglobin values mainly depended on specific anemia therapy and not on particular ACEi drug. Conclusion. Fosinopril carries less risk of hyperkalemia in hypertensive hemodialysis patients than enalapril. Although definite conclusion may be drawn after well-designed studies, the results presented in this pilot study suggest that fosinopril may be recommended for hypertensive hemodialysis patients who are at risk to develop inter-dialytic hyperkalemia.
Incidence of penile curvature in various forms of hypospadias
?or?evi? Miroslav,Stojanovi? Borko,Stojsavljevi? Miodrag,Du?i? Sinia
Srpski Arhiv za Celokupno Lekarstvo , 2009, DOI: 10.2298/sarh0908391d
Abstract: Introduction. Hypospadias is a congenital anomaly of the penis, characterised by ectopically positioned urethral meatus and associated anomalies (cryptorchidism, inguinal hernia, penile curvature). Proximal forms of hypospadias, as severe cases, are particularly accompanied by penile curvature (chordee). Distal types are considered to be mild degrees. Objective. To determine the incidence of congenital curvature within various forms of hypospadias in order to signify preoperative and intraoperative diagnosis of chordee as a part of hypospadias repair. Methods. The total of 454 patients with hypospadias were treated surgically in a five-year period (2001-2006.) at the University Children's Hospital of Belgrade. The patients were divided into two groups according to the surgeon who had treated them. Only the first group of patients was tested for chordee as a part of standard procedure and complete treatment. In both groups we analyzed the number of patients treated for penile curvature within various types of hypospadias. We also compared scores in the two groups using Fisher test and χ2-test. Results. Scanning retrospective, 104 cases (22.9%) of diagnosed and surgically corrected chordee were determined. In 31.6% of patients from the first group and 11.6% of patients from the second group we diagnosed and corrected some form of penile curvature was. Chordee was significantly more frequent in the first group, regarding hypospadias in general (p<0.01), as well as distal (p<0.05) and mid shaft forms (p<0.01). Conclusion. Penile curvature is not uncommon in hypospadias. In this study we report a significantly higher frequency as related to the patients in the second group who were not tested for curvature during hypospadias treatment. This is why standard techniques in hypospadias repair should definitely include the diagnosis and surgical correction of penile curvature.
Calibration procedure for zenith plummets
Vukan OGRIZOVI?,Sinia DEL?EV,Jelena GU?EVI
Geonauka , 2013,
Abstract: Zenith plummets are used mainly in applied geodesy, in civil engineering surveying, for materialization of the local vertical. The error of the vertical deflection of the instrument is directly transferred to the error of the observing construction. That is why a proper calibration procedure for the zenithlot is required. Metrological laboratory of the Faculty of Civil Engineering in Belgrade developed such calibration procedure. Here we present a mathematical model of the calibration and some selected results.
Dejan Bokonji?,Mirjana Miri?,Sinia Risti?,Pedja Kova?evi
Acta Facultatis Medicae Naissensis , 2005,
Abstract: The aim of the paper was to test the association between serum C-reactive protein (CRP) and serum ferritin and its role in the severity of anemia of hemodialysis patients. A cross-sectional study was conducted on the patients with an end-stage renal disease who underwent HD treatment with acetate basis dialysate and polysulfone membranes. There were 36 patients overall (f=15, m=21), 25 of whom were non-diabetic HD patients and 11 diabetic HD patients. There was an approximate significant inverse correlation between serum CRP and hemoglobin level and also a significant positive correlation between serum CRP and serum iron as well as an approximate significant inverse correlation between serum CRP and HD adequacy. A significant positive correlation between serum CRP and serum ferritin was registered. Malnutrition-inflammation complex syndrome may increase serum ferritin concentration apart from iron status, and needs more attention during iron therapy for the treatment of anemia in regular HD patients.
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