Improved Method for Long-Term Frequency Stability Measurement Using Vector Voltmeter

This paper proposes a novel approach for the improvement of the long-term frequency stability measurement using an obsolete phase meter. The hypothesis of the paper states it is possible to fully automate measurement process and reduce measurement time using the standard method supported by bespoke PC software. This theory was examined in detail and experimentally validated using GPS standard method. The results of the experiment confirmed that measurement time can be reduced more than 50 %, at the expense of a measurement uncertainty increase. Still, the estimated measurement uncertainty of the proposed method is more than satisfactory for the calibration purpose of the most common oscillator types including rubidium frequency standards

Association between risk factors, basal viral load, virus genotype and the degree of liver fibrosis with the response to the therapy in patients with chronic hepatitis C virus infection

© 2015, Institut za Vojnomedicinske Naucne Informacije/Documentaciju. All rights reserved. Background/Aim. Hepatitis C is an important sociomedical problem worldwide due to frequent progression to chronic dis-ease, occurrence of liver cirrhosis and hepatocellular carcinoma. Standard pegylated interferon alfa 2a plus ribavirin therapy results in resolution of infection only in 50% of patients. The aim of this study was to determine the association of various factors with re-sponse to the therapy in patients with chronic heptitis C virus (HCV) infection. Age and sex of patients, inoculation risk factors, histopathological changes in the liver, viral load and HCV geno-type were analyzed. Methods. The study included a group of 121 patients with chronic HCV infection. The treatment was carried out 24 weeks for virus genotype 2 and 3, and 48 weeks for geno-type 1 and 4. The degree of histopathological changes in the liver was determined by hematoxylin and eosin staining, whereas polimerase chain reaction was used for HCV genotyping. Results. In the group of non-responding patients genotype 1 was repre-sented with 100%, while in the other groups, although predomi-nantly present, its percentage was lower. Unresponsiveness to therapy and relapse of disease were associated with higher viral load and advanced fibrosis. Intravenous use of psychoactive sub-stances, as a risk factor, was present in a high percentage in the group of patients with sustained response, while blood transfusion and dialysis were leading risk factors in the group of relapse re-sponders and non-responders. Conclusion. The results of our study showed that the treatment outcome of chronic HCV infec-tion was associated with baseline HCV ribonucleic acid, HCV genotype, route of infection and the degree of histopathological changes in the liver

Expression of estrogen and progesterone receptors in subcutaneous endometriosis

Endometriosis is a clinical disorder defined by the presence of functional endometrial tissue outside the uterine cavity. Depending on the localization of the endometrial tissue related to the pelvis, the endometriosis can be classified either as intrinsic or extrinsic. The prevalence of endometriosis is difficult to determine. Statistical data show that endometriosis could be associated both with female infertility (20%) and pelvic pains (24%), while in 4.1% of affected women, endometriosis has asymptomatic forms. The total prevalence of endometriosis is estimated to be between 5-10%. A 35-year-old woman from Knic, Serbia, was admitted to the Obstetrics and Gynecology Clinic of the Clinical Center in Kragujevac for surgical treatment of a suspicious swelling in the pubic region. Following surgical intervention, a nut-sized tumor was removed and sent for both pathohistological and immunohistochemical analysis. The results confirmed the presence of subcutaneous endometriosis positive for both estrogen and progesterone receptors. Endometriosis is usually described as a steroid hormone-dependent change that resembles the eutopic endometrial tissue characteristic for the presence of both glandular and stromal tissues. Given the fact that endometrial lesions are estrogen-dependent tumors, a crucial factor in the development of endometriosis is a late exposure to the hormone, mostly estrogen. Spontaneous subcutaneous endometriosis is rarely observed, but it could be assumed if there is recurrent pelvic pain which intensifies during menstruation. Given the fact that endometriosis coexists with different autoimmune diseases, multidisciplinary approaches are required for its proper diagnosis

Influence of Running Conditions on Resonant Oscillations in Fresh-Air Ventilator Blades Used in Thermal Power Plants

High-frequency cyclic load of fresh air supply to ventilator blades in thermo energetic facilities can cause the occurrence of fretting in the pressed overlap of ventilator shaft and socket. These loads can be generated by the resonant oscillations of ventilator blades and thermal residual stress due to welding. To prevent running in resonant conditions, the manufacturer of the ventilator defined a procedure of adjusting blades natural frequency in the process of production, as well as period control during exploitation period The numerical simulations and the accelerations measured and presented in this paper, enabling analysis of mass changes and rotation rate effects on resonant oscillations occurrence in fresh air ventilator

Characterization of a low cost Lagenaria vulgaris based carbon for ranitidine removal from aqueous solutions

Practical aspects of Lagenaria vulgaris shell conversion to activated carbon were examined along with its use in ranitidine adsorption. Kinetics and isotherms of adsorption onto Lagenaria vulgaris carbon (LVC) were correlated to several theoretical adsorption models. The best fit was found in the case of Langmuir and pseudo-second-order model indicating monolayer adsorption. The influence of pH under kinetic study showed slightly hindered adsorption below pH 4. The optimal adsorbent dosage was set to 1 g/L. LVC was characterized by several complementary techniques, including wet chemical techniques such as Boehm's titrations and determination of pH(pzc) and pH of LVC, which revealed neutral nature of the adsorbent. N-2 sorptometry determined specific surface area of 665 m(2)/g and significant ratio of micropores in the sample with maximum wall's diameter of 2.2 nm. Fourier transform infrared spectroscopy (FTIR) confirmed the role of lignin and cellulose in the formation of the final LVC structure. Porous structure of the material was proved by using scanning electron microscopy. Preparation of LVC material drew attention as an easy and low-cost process for production of a highly efficient adsorbent which exhibited fast kinetics of ranitidine removal in the first minutes of contacting and large adsorption capacity (315.5 mg/g) at equilibrium

Sexual dimorphism of medium-sized neurons with spines in human nucleus accumbens

The nucleus accumbens is a limbic nucleus, representing part of the striatum body, and together with the caudate nucleus and putamen, it lies on the septum. The aim of this study was to examine morphological sexual dimorphism in spine density and also to undertake an immunohistochemical study of expression for estrogen and progesterone receptors in the medium-sized neurons in the nucleus accumbens. The research was conducted on twenty human brains of persons of both sexes, between the age of 20-75 years. The Golgi method was applied to determine the types and subtypes of neurons, morphologies of soma, dendrites and axons, as well as the relations between the cells and glial elements. The following were quantitatively examined: the maximum diameter of the neurons, the minimal diameter of the neurons, and the total length of the dendrites. The expression of receptors for estrogen and progesterone, their distribution and intensity were defined immunohistochemically. The parameters of the bodies of neurons in the shell and core of the nucleus accumbens were studied in both men and women. No statistically significant differences were found. Examination of the spine density showed statistical significance in terms of a higher density of spines in women. Immunohistochemically, in the female brain estrogen expression is diffusely spread in a large number of neurons; it is extra nuclear, of granular appearance and high intensity. In the male brain, expression of estrogen is visible and distributed over about one half of different types of neurons; it is extra nuclear, of granular appearance, mostly of middle and low staining intensity. Expression of progesterone in the female brain was very discreet and on a very small number of neurons; it was extra nuclear and with a weak staining intensity. Expression of progesterone in the male brain was distributed on a small number of neurons. It had a granular appearance, it was extra nuclear, with a very low staining intensity. Our results show differences in the morphology as well as expression of receptors for estrogen and progesterone on medium-sized neurons with spines in the nucleus accumbens of men and women

Experimental and numerical study of globe valve housing

Complex structure experimental analysis has always been a huge challenge for researchers. Conventional experimental methods (e.g., strain gauges) give only limited data sets regarding measurement on critical areas with high geometrical discontinuities. A 3D Digital Image Correlation method is an optical method that overcomes the limitations of conventional methods and enables full-field displacement and strain measurement of geometrically complex structures. System Aramis, based on Digital Image Correlation method, is used for experimental analysis and numerical model verification in this paper. Investigated complex structure is sphere/cylinder junction on globe valve housing subjected to axial loading. The highest experimentally measured von Mises strain values around 0.15% are recorded on cylinder/sphere intersection. Von Mises strain values on cylindrical and spherical part are several times smaller than on intersection itself. It is important to emphasize that, to the authors best knowledge, this is the first paper showing experimental results of 3D full and strain field of geometrically complex structure (sphere/cylinder intersection) on the intersection itself on pressure equipment. It is proven that 3D Digital Image Correlation method is fast and versatile method for recording strain during loading of complex structures

Comparison of exercise, dobutamine-atropine and dipyridamole-atropine stress echocardiography in detecting coronary artery disease

BACKGROUND: Dipyridamole and dobutamine stress echocardiography testing are most widely utilized, but their sensitivity remained suboptimal in comparison to routine exercise stress echocardiography. The aim of our study is to compare, head-to-head, exercise, dobutamine and dipyridamole stress echocardiography tests, performed with state-of-the-art protocols in a large scale prospective group of patients. METHODS: Dipyridamole-atropine (Dipatro: 0.84 mg/kg over 10 min i.v. dipyridamole with addition of up to 1 mg of atropine), dobutamine-atropine (Dobatro: up to 40 mcg/kg/min i.v. dobutamine with addition of up to 1 mg of atropine) and exercise (Ex, Bruce) were performed in 166 pts. Of them, 117 pts without resting wall motion abnormalities were enrolled in study (91 male; mean age 54 ± 10 years; previous non-transmural myocardial infarction in 32 pts, angina pectoris in 69 pts and atypical chest pain in 16 pts). Tests were performed in random sequence, in 3 different days, within 5 day period under identical therapy. All patients underwent coronary angiography. RESULTS: Significant coronary artery disease (CAD; ≥50% diameter stenosis) was present in 69 pts (57 pts 1-vessel CAD, 12 multivessel CAD) and absent in 48 pts. Sensitivity (Sn) was 96%, 93% and 90%, whereas specificity (Sp) was 92%, 92% and 87% for Dobatro, Dipatro and Ex, respectively (p = ns). Concomitant beta blocker therapy did not influence peak rate-pressure product and Sn of Dobatro and Dipatro (p = ns). CONCLUSION: When state-of-the-art protocols are used, dipyridamole and dobutamine stress echocardiography have comparable and high diagnostic accuracy, similar to maximal post-exercise treadmill stress echocardiography

Obstetric and gynecological intervention in women with Bernard-Soulier syndrome: Report of two cases

Introduction. Bernard-Soulier syndrome (BSS) is a rare inherited bleeding disorder characterized by giant platelets thrombocytopenia e prolonged bleeding timee frequent hemorrhages with considerable morbidity. Data on the outcome of pregnancy and gynecological intervention in BSS are rare and there are no general therapeutic recommendations. Cases Outline. We report two cases of BSS. In the first case a 29-year-old patient with BSS was admitted in 8 weeks of gestation. The diagnosis of BSS was made on the basis of prolonged bleeding time, giant-platelets thrombocytopenia, and absent ristocetin-induced platelet aggregation. In 38 week of gestation Cesarean section, with platelets transfusion preparation, was performed. Obstetric intervention passed without complication. Postoperative course was complicated with a three-week vaginal bleeding resistant to platelet transfusion. Neonate platelet count was normal. Our second case was a 28-year-old patient with BSS, hospitalized for ovarial tumor surgery. The patient was prepared for the intervention with platelets transfusion. The surgery was uncomplicated, but on the second postoperative day a massive vaginal bleeding, resistant to the platelet transfusion, developed. Bleeding control was achieved with activated recombinant factor VII. Twelve hours the patient developed later hypertensive crisis with epileptic seizure due to subarachnoid hemorrhage. Therapy was continued with platelet transfusion, antihypertensive and antiedema drugs. PH examination of tumor tissue showed hemorrhagic ovarial cyst. Conclusion. Obstretic and gynecological intervention in women with BSS may be associated with a life-threatening bleeding thus requiring a multidisciplinary approach with adequate preparation. Because of the limited data in the literature, it is not possible to provide firm management recommendations and each case should be managed individually