Frequency Stability Measurement in the Frequency Domain

Дисертација истражује најприхватљивије методе мерења стабилности фреквенције у фреквенцијском домену, односно мерење вредности величине „фазни шум“, приликом процеса еталонирања мерне опреме. Када се говори о мерној опреми која је предмет еталонирања, дисертација је, пре свега, окренута ка еталонирању врхунских комерцијалних стандарда (еталона) фреквенције. Приказана истраживања су била основ за покретање и реализацију истраживачко-развојног пројекта у оквиру Министарства одбране, који је имао за циљ оспособљавање метролошке лабораторије Техничког опитног центра Војске Србије за потпуно еталонирање мерне опреме из области времена и фреквенције. Различите методе мерења подразумевају и различите мерне могућности, као и врло широк спектар еталонске и мерне опреме која се користи при њиховој реализацији. У дисертацији се приказују различити начини мерења фазног шума и описују методе реализоване на основу доступне мерне опреме. Како се ради о методама упоредне анализе референтног и мереног сигнала, посебно критична позиција је одабир референце, односно референтног еталона. Истраживање је довело до закључака којима је предложен метод мерења потребне и довољне мерне несигурности као и начин реализације изабране методе, односно одабир еталонске мерне опреме. У циљу увођења мерне методе у употребу, извршена су и приказана мерења на различитим типовима и врстама мерне опреме. Валидација методе је остварена билатералним поређењем са Дирекцијом за мере и драгоцене метале, Група за време, фреквенцију и дистрибуцију времена. Да је могуће реализовати методу мерења фазног шума приликом еталонирања најквалитетнијих осцилатора је постављена хипотеза дисертације, која је истраживањем доказана и практично спроведена. Крајњи резултат истраживања је довео до увођења признате методе еталонирања фазног шума, први путDisertacija istražuje najprihvatljivije metode merenja stabilnosti frekvencije u frekvencijskom domenu, odnosno merenje vrednosti veličine „fazni šum“, prilikom procesa etaloniranja merne opreme. Kada se govori o mernoj opremi koja je predmet etaloniranja, disertacija je, pre svega, okrenuta ka etaloniranju vrhunskih komercijalnih standarda (etalona) frekvencije. Prikazana istraživanja su bila osnov za pokretanje i realizaciju istraživačko-razvojnog projekta u okviru Ministarstva odbrane, koji je imao za cilj osposobljavanje metrološke laboratorije Tehničkog opitnog centra Vojske Srbije za potpuno etaloniranje merne opreme iz oblasti vremena i frekvencije. Različite metode merenja podrazumevaju i različite merne mogućnosti, kao i vrlo širok spektar etalonske i merne opreme koja se koristi pri njihovoj realizaciji. U disertaciji se prikazuju različiti načini merenja faznog šuma i opisuju metode realizovane na osnovu dostupne merne opreme. Kako se radi o metodama uporedne analize referentnog i merenog signala, posebno kritična pozicija je odabir reference, odnosno referentnog etalona. Istraživanje je dovelo do zaključaka kojima je predložen metod merenja potrebne i dovoljne merne nesigurnosti kao i način realizacije izabrane metode, odnosno odabir etalonske merne opreme. U cilju uvođenja merne metode u upotrebu, izvršena su i prikazana merenja na različitim tipovima i vrstama merne opreme. Validacija metode je ostvarena bilateralnim poređenjem sa Direkcijom za mere i dragocene metale, Grupa za vreme, frekvenciju i distribuciju vremena. Da je moguće realizovati metodu merenja faznog šuma prilikom etaloniranja najkvalitetnijih oscilatora je postavljena hipoteza disertacije, koja je istraživanjem dokazana i praktično sprovedena. Krajnji rezultat istraživanja je doveo do uvođenja priznate metode etaloniranja faznog šuma, prvi putThe dissertation examines the most acceptable methods for measuring the frequency stability in the frequency domain, that is, measuring the value of the "phase noise", during the process of measuring equipment calibration. When it comes to measuring equipment as a subject of calibration, the dissertation is, first of all, oriented towards the calibration of the highest commercial frequency standards. The presented researches were the basis for initiation and realization of the research and development project within the Ministry of Defense, which was aimed at training the metrology laboratory of the Technical Test Center of the Serbian Army for complete calibration of measuring equipment in the area of time and frequency. Different measurement methods also involve different measurement possibilities, as well as a very wide range of calibration and measuring equipment used in their realization. Different methods of measuring phase noise are described in the dissertation and they describe realized methods based on available measuring equipment. As for methods of comparative analysis of the reference and measured signal, a particularly critical position is the selection of the reference, that is, the reference oscillator. The research led to conclusions suggesting the method of measuring the necessary and sufficient measurement uncertainty, as well as the method of realization of the chosen method, i.e. selection of the standard measuring equipment. In order to put the measurement method into practice, measurements were performed on different types of measuring equipment. Validation of the method was achieved by bilateral comparison with the Directorate of Measures and Precious Metals, Group for time, frequency and time dissemination. The possibility to realize the method of phase noise measurement during the calibration of the highest quality oscillators is a hypothesis of the dissertation that has been set up, and has been proven and practically carried out by the research. The final result of the research led to the introduction of a recognized calibration method of the phase noise, for the first time in the Republic of Serbia

Resveratrol Protects Cardiac Tissue in Experimental Malignant Hypertension Due to Antioxidant, Anti-Inflammatory, and Anti-Apoptotic Properties

Hypertension is one of the most prevalent and powerful contributors of cardiovascular diseases. Malignant hypertension is a relatively rare but extremely severe form of hypertension accompanied with heart, brain, and renal impairment. Resveratrol, a recently described grape-derived, polyphenolic antioxidant molecule, has been proposed as an effective agent in the prevention of cardiovascular diseases. This study was designed to examine chronic resveratrol administration on blood pressure, oxidative stress, and inflammation, with special emphasis on cardiac structure and function in two models of experimental hypertension. The experiments were performed in spontaneously (SHRs) and malignantly hypertensive rats (MHRs). The chronic administration of resveratrol significantly decreased blood pressure in both spontaneously and malignant hypertensive animals. The resveratrol treatment ameliorated morphological changes in the heart tissue. The immunohistochemistry of the heart tissue after resveratrol treatment showed that both TGF-β and Bax were not present in the myocytes of SHRs and were present mainly in the myocytes of MHRs. Resveratrol suppressed lipid peroxidation and significantly improved oxidative status and release of NO. These results suggest that resveratrol prevents hypertrophic and apoptotic consequences induced by high blood pressure with more pronounced effects in malignant hypertension

SURGICAL TREATMENT OF THE RHEUMATOID FOOT

Cilj je ovog članka prikazati činjenice vezane uz kirurško liječenje stopala kod pacijenata s reumatoidnim artritisom. Reumatski upalni proces pogađa vezivno tkivo, zglobove, ligamente, tetive, hrskavicu i kosti uzrokujući deformaciju, bol i gubitak funkcije. Osobito je razoran na stopalima. Deformacije zbog reumatoidnog artritisa veće su nego u drugim reumatskim bolestima. Česta deformacija prednjeg dijela reumatoidnog stopala jest haluks valgus. Na metatarzofalangealnim zglobovima ostalih prstiju, osobito drugom, česte su subluksacija i potpuna dislokacija, a na prstima se razvijaju fleksija proksimalnog interfalangealnog zgloba te fleksija ili ekstenzija distalnog interfalangealnog zgloba. Stražnji dio stopala postupno, poslije i u manjoj mjeri biva zahvaćen bolešću. Učinjen je velik napredak u liječenju reumatskih bolesti lijekovima i kirurški. Primjenjuje se nekoliko rekonstruktivnih metoda. Za deformacije prvog traka stopala: artrodeza prvoga metatarzofalangealnog zgloba, Kellerova resekcija ili resekcija Mayova tipa, implantacijska artroplastika, sinoviektomija, osteotomija prve metatarzalne kosti. Za ostale metatarzofalangealne zglobove: tenotomije i produživanje tetiva ekstenzora, otvoreno opuštanje metatarzofalangealnih zglobova, sinoviektomija, resekcija baze proksimalne falange, metatarzalna kondilektomija, resekcija metatarzalne glavice, osteotomija metatarzalne kosti. Za prste: proksimalna interfalangealna resekcija, proksimalna interfalangealna artrodeza, distalna interfalangealna resekcija, stabilizacija prstiju sindaktilijom. Resekcijske artroplastike, skraćujući koštane strukture, poboljšavaju pokretljivost, ali je njihov rezultat nepredvidiv. Za stražnji dio stopala: artrodeza talonavikularnog, suptalarnog, kalkaneokuboidnog zgloba i zgloba gležnja ili aloartroplastika gležnja. Na vrijeme indicirano, dobro planirano i provedeno kirurško liječenje obično daje dobre rezultate. Ono nalaže intenzivnu suradnju pacijenta, reumatologa i ortopeda.The aim of this article is to present certain facts associated with rheumatoid foot surgery. Arthritic disease processes attack the joints, ligaments, tendons, cartilage, and bones, causing deformity, pain, and loss of function. Their effect on the feet can be devastating. Deformities secondary to rheumatoid arthritis are more severe than those in other forms of arthritic diseases. A common deformity of the forefoot is hallux valgus. The lesser metatarsophalangeal joints, especially the second one, commonly show lateral subluxation and total dislocation, and the toes develop flexion of the proximal interphalangeal joint and flexion or extension of the distal interphalangeal joint. The hindfoot is less affected by the disease process, most oft en only in the late stage of the disease. Great progress has been made in the medical and surgical treatment of arthritic diseases. Several reconstructive procedures can be performed. For first ray deformities: first metatarsophalangeal joint fusion, Mayo or Keller resection, implant arthroplasty, synovectomy, proximal osteotomy of the first metatarsal, and metatarsocuneiform fusion. For lesser metatarsophalangeal joints: extensor tenotomies, open metatarsophalangeal joint release, synovectomy, base resection, metatarsal condylectomy, metatarsal head resection, base and metatarsal head resection, and lesser metatarsal osteotomy. For the toes: proximal interphalangeal joint arthroplasty, proximal interphalangeal joint fusion, distal interphalangeal joint arthroplasty, proximal phalangeal base resection, and digital stabilization by syndactylization. Resection arthroplasty improves motion by shortening skeletal structures and providing new gliding surfaces, but the results are unpredictable. For the rheumatoid hindfoot, arthrodesis of the talonavicular, subtalar, calcaneocuboid, and tibiotalar joints or ankle arthroplasty can be performed. The results of a well-planned and performed surgical treatment, indicated in time, are usually good. Co-operation between the patient, rheumatologist, and surgeon is required

Improved Method for Calibration and Nonlinearity Correction of Microwave Power Sensor

Power sensor nonlinearity contributes significantly to the increase of the microwave power measurement uncertainty. Current methods for sensor calibration do not provide correction of the results, due to the sensor nonlinearity. The paper describes an improved method and an automated measuring system based on it for power sensor calibration that enables the correction of the results, taking into account amplitude and frequency dependent nonlinearity. The novel calibration method is based on the application of high-linearity thermistor power transfer standard. The power sensor calibration process is fully automated and improved by applying the automated measuring system, PC and VEEpro software. Performed calculation of the calibration measurement uncertainty and the analysis of power measurement uncertainty budget indicate that the new calibration method allows the correction of sensor nonlinearity and contributes to significant reduction of the microwave power measurement uncertainty, ranging from 15,8% to 40,5%. Experimental results and validation confirm the applicability of the improved calibration method and prove the existence of significant dependence of sensor nonlinearity on the power level, but also on the frequency of the measured microwave power

The error at application of Fleishmann\u27s formula for the estimation of milk total solids

Pored velikog napretka u instrumentalnoj analitičkoj tehnici za gravimetrijsko određivanje suhe tvari mlijeka, još uvijek to određivanje je sporo i skupo s obzirom na potreban rad i instrumente.Investigations were carried out upon the differences between total solids of milk determined gravimetrically and calculated by Fleischmann\u27s formula. In two series of analyses were found differences between gravimetric and calculated percentages 0.31 and 0.19 respectively. The calculated percentages were higher than those determined gravimetrically. The obtained differences were significant at P<0.05 and P<0.01 respectively. It was pointed out the importance of systematic error in the estimation of total solids of milk by using Fleischmanns formula and the need for a new formula which would be adapted to the specific composition of Yugoslav milk

The red wine polyphenol, resveratrol improves hemodynamics, oxidative defence and aortal structure in essential and malignant hypertension

Resveratrol the polyphenolic antioxidant molecule has been proposed as an effective agent in the prevention of several pathological conditions, thus this study was aimed to evaluate its chronic effects on functional and structural remodeling of the aorta in spontaneously (SHR) and malignantly hypertensive rats (MHR). Resveratrol significantly decreased arterial pressure and improved regional hemodynamic parameters, bioavailability of nitric oxide, ameliorated morphological changes in the tunica media and smooth muscle of the aorta, preserved endothelium, reduced inflammation and apoptosis in both SHR and MHR, but excrete more beneficial effects on SHR. Resveratrol suppressed lipid peroxidation, significantly improved oxidative status and reduced levels of lipids. These results suggest the cardiovascular benefits of resveratrol dietary enrichment in both experimental models of hypertension