55 research outputs found
EVALUATION OF THE IMPORTANCE OF BIOCHEMICAL PARAMETERS IN RELATION TO ULTRASONOGRAPHIC FINDING IN ECTOPIC PREGNANCY DIAGNOSIS
The implantation of the fertilized egg outside the uterine cavity leads to the development of ectopic pregnancy. The incidence of ectopic pregnancy is 1/100 births. The most common place of ectopic implantation of the fertilized ovum is the oviduct (98%) with predilection for the ampullar part of the Fallopian tube. The aim of this study was to determine the predictive importance of beta-hCG and progesterone concentration compared to ultrasonographic finding in the ectopic pregnancy diagnosis.We examined 24 patients with ectopic pregnancies which we divided according to the days of amenorrhea into two groups: the first group with the total of 28 patients from 16–42 days and another group of 8 patients with amenorrhea longer than 42 days. The control group was comprised of 20 patients with vital intrauterine pregnancy, gestational age of 42-52 days. Blood samples for quantitative determination of hormones were collected on three occasions after 48 hours in the forenoon time in the examined and control group of pregnant women. Ultrasonographic examinations of all pregnant women were carried out immediately after blood sampling, with the trans-vaginal approach using "make loop" option, and measurements with an accuracy of 0.1 mm.Mean values for beta-hCG range from 698-1774 mlU/ml in the first group of pregnant women, and in the second group of 1896 mlU/ml to 4410 mlU/ml with a statistically significant difference compared to the values in the control group (p <0.001). The concentration of progesterone in the first group of women ranging from 41-70 nmol/l, and in the second group of 76-94 nmol/l which is also the statistically significant difference compared to the control group (p<0.002). We have shown that ultrasonographic finding with its parameters reliably predicts the values of biochemical parameters both in normal intrauterine pregnancy and in the case of ectopic pregnancy.Embryo viability and implantation place condition the values of biochemical parameters, which makes establishing the correct diagnose difficult by following only these markers. It is necessary to combine the growth dynamics of these hormones with ultrasonographic finding as the gold standard in diagnosing ectopic pregnancy
PREDICTIVE VALUE OF FETAL NUCHAL TRANSLUCENCY IN SCREENING OF CHROMOSOMAL ABERRATIONS
In search for specific early ultrasound signs that could indicate an increased risk of hereditary or acquired disorders of the fetus, scientific researches confirm the value of exceptional ultrasound findings of nuchal translucencey (NT). The aim of the study was to determine the predictive value of the diameter of fetal NT in the detection of chromosomopathy. The investigation included 317 pregnant women with monofetal pregnancies, gestational age 11-14 weeks. The control group consisted of pregnant women in whom, after amniocentesis, a regular result of fetal karyotype was obtained. The limits of physiological and pathological findings of the NT value were not determined; instead, we used the diameters of NT that were obtained in pregnant women with pathological score of amniocentesis as potentially pathological values. Mean value of NT in the control group was 1.92±0.39mm, and in the group with pathological findings of fetal karyotype it was 2.49±0.37mm, which is a statistically significant difference (p<0.05). Mean value of the rump-crown length in the control group was 64.83±8.23mm, and the group with pathological karyotype 60.12±8.48mm; gestational age in the control group was 7.10±87.40 days, and in the pathological one 85.69±3.98 days, which speaks of homogeneity of the investigated sample (p>0.05).The probability that a patient with negative NT findings be healthy is 0.97. NT sensitivity as a marker for chromosomopathy was 0.97. The rate of false positive findings was 0.027. Specificity of NT as a marker for chromosomopathy was 0.97. The probability that a patient with positive findings NT really be ill was 0.66.Valid findings of NT can be considered safe ultrasonographic markers in the assessment of absence of chromosomopathy. Pathological finding, given the low positive predictive value of NT, must be amended by other prenatal tests before a pregnant woman is advised on prenatal invasive diagnostics
Neurološke manifestacije hipereozinofilnog sindroma – pregled literature
Hypereosinophilic syndrome is a rare disorder of the hematopoietic system. The disease is characterized by continuously high number of eosinophils (>1.5x109/L) for more than six months. Other possible causes of hypereosinophilia, such as allergic and parasitic diseases, malignant disease, Churg-Strauss disease and infection should be eliminated. The most common manifestations of hypereosinophilic syndrome are pulmonary, skin, gastrointestinal, cardiac difficulties and neurologic lesions. Numerous neurologic lesions have been described, in particular of the central and peripheral nervous systems. Review of the literature revealed the following to have been recorded so far: mononeuritis multiplex, sensory polyneuropathy, radiculopathy, myalgia, myositis and perimyositis, neuropathy, ataxia, paraplegia, ophthalmologic abnormalities, optic neuritis, hemiplegia-hemiparesis, spasmodic quadriplegia, seizures, meningitis, cerebral infarction, organic psychosyndrome, other mental changes, stroke, temporal arteritis, leptomeningeal dissemination, memory deficits and dysarthria.Hipereozinofilni sindrom je rijetka bolest hematopoetskog sustava. Bolest je obilježena visokim brojem eozinofila (>1,5x109/L) duže od šest mjeseci, uz uvjet da su isključeni drugi mogući uzroci hipereozinofilije kao što su alergija i parazitne bolesti, maligne bolesti, Churg-Straussova bolest i druge infekcijske bolesti. Većina kliničkih manifestacija hipereozinofilnog sindroma obuhvaća oštećenja pluća, kože, probavnog sustava, srčane poremećaje i neurološka oštećenja. Opisana su brojna neurološka oštećenja središnjeg i perifernog živčanog sustava. Pretraživanjem literature nalaze se moguće neurološke manifestacije bolesti kao što su mononeuritis multiplex, senzorna polineuropatija, radikulopatija, mijalgija, miozitis i perimiozitis, neuropatija, ataksija, paraplegija, oftalmološki poremećaji, optički neuritis, hemiplegija-hemipareza, spastička tetraplegija, epileptični napadaji, meningitis, ishemijski moždani udar, psihoorganski sindrom i drugi mentalni poremećaji, temporalni arteritis, leptomeningealna diseminacija, poremećaji pamćenja i dizartrija
The estimation of compressive strength of normal and recycled aggregate concrete
Procena čvrstoće pri pritisku se postavlja kao važan zadatak proizvođačima betona, naročito pri projektovanju betonskih mešavina i obezbeđenju zahtevanog kvaliteta proizvedenog betona. U radu je prikazano poređenje eksperimentalnih rezultata čvrstoće pri pritisku betona sa prirodnim i recikliranim agregatom sa rezultatima dobijenim na osnovu jednačina prikazanih u tehničkoj regulativi. Prikazan je koeficijent determinacije eksperimentalnih podataka i rezultata dobijenih na osnovu preračuna prema jednačinama datim u EN 1992-1-1, ACI 209 i tabeli za preračun datoj u SRPS U.M1.048. Prikaz zavisnosti čvrstoće pri pritisku betona na osnovu jednačina datih u radu se odnosi na određivanje zavisnosti u odnosu na vrstu upotrebljenog cementa i starosti betona negovanog na konstantnoj temperaturi.Estimation of concrete strength is an important issue in ready-mixed concrete industry, especially, in proportioning new mixtures and for the quality assurance of the concrete produced. In this article, on the basis of the existing experimental data of compressive strength of normal and recycled aggregate concrete and equation for compressive strength calculating given in Technical regulation are compared. The accuracies of prediction by experimental data obtained in laboratory as well as by EN 1992-1-1, ACI 209 and SRPS U.M1.048 are compared on the basis of the coefficient of determination. The determination of the compressive strengths by the equation described here relies on determination of type of cement and age of concrete with the constant curing temperature
Frost resistance of concrete with crushed brick as aggregate
Predmet istraživanja su betoni spravljeni sa recikliranom opekom kao agregatom. Eksperimentalni rad je obuhvatio više vrsta betona spravljenih sa istom količinom cementa (385 kg/m3) i istom konzistencijom (sleganje oko 1 cm). Kao agregat je korišćena reciklirana opeka i kombinacija reciklirane opeke i prirodnog rečnog agregata. Posmatran je uticaj upotrebljenih frakcija drobljene opeke i njihovog procentualnog učešća na čvrstoću pri pritisku, upijanje vode i otpornost prema dejstvu mraza. Na osnovu rezultata eksperimentalnih istraživanja može se zaključiti da se primenom reciklirane opeke kao agregata dobija novi kompozitni materijal sa zadovoljavajućim fizičko - mehaničkim karakteristikama.The investigation included concrete made by using recycled brick as aggregate. Experimental work included several types of concrete made with the same cement content (385 kg/m3), and same consistency (slump about 1 cm). Recycled brick and combination of natural river aggregate and recycled brick were used as aggregates. The influence of percentage and grain size of crushed brick aggregate on concrete compressive strength, water absorption and frost resistance were observed. On the basis of the results obtained during experimental research, a general conclusion can be drawn that the application of recycled concrete as aggregate can lead to new composites with satisfactory physical-mechanical properties
Resistance of CEM III/B based materials to acid attack
Cementni materijali u poljoprivrednim i drugim industrijskim objektima izloženi su dejstvu kiselina. Zbog toga vek konstrukcija zavisi od trajnosti maltera ili betonskih elemenata u agresivnoj sredini. U radu je predstavljena otpornost na koroziju koja je uzrokovana sulfatnom, nitratnom, ureom, mlečnom i sirćetnom kiselinom. Skenirajuća elektronska mikroskopija (SEM) korišćena je da se ispita efekat agresivnih rastvora na mikrostrukturu i mehaničke osobine maltera. Hemijska otpornost prizmi od maltera i dve vrste betona testirana je prema metodi Koch-Steinegger. Kako je uslov za otpornost na agresivne rastvore taj da zatezna čvrstoća maltera nije manja od 70% u odnosu na referentne prizme negovane u vodi, može se zaključiti da su malter i beton, napravljeni sa CEM III/B, u ovom istraživanju otporni na sve kiseline kojima su tretirani. .Cement based materials in the agricultural and other industrial structures are exposed to acid attack. That is the reason why the service life of structure depends on the durability of mortar or concrete elements in aggressive environment. Resistance to corrosion caused by sulphate, nitrate, carbamide, lactic acid and acetic acid was presented. Optical and scanning electron microscopy (SEM) was used to examine the effect of aggressive solutions on the microstructure and mechanical properties of mortar. The chemical resistance of mortar prisms and two types of concrete were tested according to the Koch-Steinegger method. As the condition for resistance in aggressive solution is that flexural strength of mortar prisms is no less than 70 % compared to referent prisms cured in water it can be concluded that mortar and concrete made with CEM III/B in this investigation are resistant to all treated acids
Some properties of ultra-high strength concrete
Značajno mesto u primeni novih materijala u građevinarstvu zauzima upotreba betona ultra visokih čvrstoća. Struktura, svojstva i tehnologija izrade ove vrsta betona se intenzivno proučava poslednjih petnaest godina. U ovom radu je prikazana mogućnost dobijanja betona ultra visokih čvrstoća na osnovu eksperimentalnih istraživanja primenom komponentnih materijala dostupnih u Srbiji. Spravljene su tri serije uzoraka sa različitim vrstama cemenata. Korišćena su čelična vlakna dužine 8mm i poprečnog preseka 0.175mm. Prikazana su fizičko-mehanička svojstva betona ultra visokih čvrstoća i analizirana je mikrostruktura ovog kompozita.Modern civil engineering is characterized with increased application of Ultra-high strength concrete (UHSC). Structure, properties and manufacturing technologies of UHSC are intensively analyzed in the last fifteen years. Possibilities of getting UHSC designed with the materials that are available in Serbian market, were tested in the experimental work; they are shown in this paper. Three series of samples were made with different types of cement. Steel fibers were used: length 8 mm, diameter 0.175 mm. Physical-mechanical properties of UHSC are presented and microstructure of concrete was observed, as well
Evaluation of air content on concrete compressive strength with classical approach and neural networks
Mnogi parametri utiču na karakteristike svežeg i očvrslog betona. Jedan od najvažnijih svakako jeste poroznost betona. Poroznost svežeg betona meri se količinom uvučenog vazduha. Uticaj uvučenog vazduha na beton i njegovu pritisnu čvrstoću istraživali su mnogi svetski istraživači. Na bazi tih istraživanja, izdvojene su dve, u praksi najviše korišćene, formule. Tehnike mekog programiranja, a posebno neuronske mreže, s formiranim bazama podataka laboratorijskih ispitivanja betona, otvaraju novi pristup u predviđanju uticaja količine uvučenog vazduha u svežem betonu na njegovu čvrstoću pri pritisku.Many parameters influence on the characteristics of fresh and hardened concrete. One of the most important characteristic of concrete is its porosity. Measure the porosity of fresh concrete is measured by the amount of entrained air. The effect of entrained air in concrete on compressive strength investigated by many authors. On the bases these works we have two formulas applicable in practice. Soft programming techniques especialy neural networks and the formation of databases related to the testing in laboratories for concrete opened up new approaches in predicting the impact of the quantity of entrained air in concrete on compressive strength
Market concentration and profitability: the empirical evidence from Serbian manufacturing industry
Utjecaj tržišne koncentracije na profitabilnost je kontroverzno pitanje u oblasti industrijske organizacije, na koje nema jasnog odgovora. Cilj istraživanja je ispitati ovaj eventualni utjecaj u kontekstu prerađivačke industrije Srbije. Temeljna hipoteza u ovom istraživanju jest da povećanje koncentracije tržišta povećava profitabilnost na tržištima zbog tajnog sporazuma dominantnih tvrtki. Hipoteza je testirana definiranjem i ocjenom modela koji opisuje utjecaj strukturnih i ostalih kontrolnih varijabli na profitabilnost tržišta, korištenjem sekundarnih podataka panela za 122 tržišta, promatrana u 2015. i 2017. godini. Podaci su dobiveni iz 30037 financijskih izvješća tvrtki iz sektora prerađivačke industrije. Model je procijenjen primjenom dvostupanjske metode najmanjih kvadrata s komponentama slučajne pogreške (EC2SLS). Rezultati istraživanja ukazuju na statistički značajan pozitivan utjecaj koncentracije tržišta na profitabilnost, što ide u prilog tradicionalnoj hipotezi tržišne snage.The impact of market concentration on profitability is a controversial question in industrial organization without a clear answer. The aim of the research is to investigate this prospective impact in the context of Serbian manufacturing industry. The main hypothesis of the research is that the increase in market concentration increases the profitability in the markets, due to the collusion of the dominant companies. We test this hypothesis by defining, estimating and testing the model describing the impact of structural and other control variables on
market profitability by using secondary panel data for 122 markets, observed in 2015 and 2017. We obtained the data from 30 037 financial reports of the manufacturing industry companies. The model was estimated by using an error component two stage least squares estimator (EC2SLS). The results indicate a statistically significant positive impact of market concentration on profitability, empirically supporting the traditional market power hypothesis
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