Applications of selected hot alkali vapors

U ovom doktorskom radu obrađena je primjena odabranih vrućih alkalijskih para. Rad je sastavljen od tri cjeline, od kojih svaka predstavlja određenu primjenu alkalijskih para. U prvoj cjelini se proučavaju svojstva i mogućnosti primjene cezijevog visokotlačnog izvora svjetlosti, te moguća poboljšanja. Također, uspoređuje se sa svojstvima natrijevog izvora svjetlosti. Potvrđeno je da je cezijev izvor svjetlosti u spektralnom smislu idealan izvor svjetla budući ima spektar vrlo sličan Sunčevom. Ipak, njegova slabija efikasnost (zbog velikog udjela infracrvenog dijela spektra) je rezultirala time da još nije našao svoju široku primjenu. Pokazano je da je udio infracrvenog dijela spektra znatno veći u cezijevom izvoru svjetlosti nego u natrijevoj izvoru, te da se taj udio smanjuje sa smanjivanjem napona napajanja. Rezultati mjerenja na cezijevom visokotlačnom izvoru svjetlosti, prezentirani u ovom doktorskom radu, iskoristit će se u budućnosti kako pri kreiranju novih izvora svjetlosti, tako i u nekim novim primjenama poput generiranje električne energije putem konverzije sunčeve svjetlosti. Druga cjelina je uključivala izradu eksperimentalnog postava za realizaciju brzinskog češlja na kaliju, te teorijsku simulaciju tih rezultata. Nakon što su već realizirane interakcije femtosekundnih pulseva s atomima rubidija i cezija, u sklopu ove disertacije realizirane su i s atomima kalija koristeći tehniku modificirane direktne spektroskopije frekventnim češljem. Potvrđena je pretpostavka da se pobuđena stanja ne uspijevaju relaksirati između dva nadolazeća pulsa femtosekundnog lasera (period repeticije 12,5 ns). Posljedica toga su promjene u strukturi Dopplerova profila kalijevih rezonantnih spektralnih linija. Teorijski model je pokazao vrlo dobro slaganje s eksperimentalnim rezultatima, što je od velike važnosti za ovu metodu u mogućim daljnjim primjenama. Isti eksperiment je proveden i u homogenom magnetskom polju. Dobiveni rezultati ukazuju na veliku mogućnost primjene kalija u magnetometriji. Zadnja cjelina doktorskog rada je uključivala mjerenje apsorpcijskih spektara alkalijskih mješavina rubidija i cezija, odnosno kalija i rubidija na različitim temperaturama. Na visokim temperaturama (preko 450°C) uočene spektralne pojave (na 418,3 nm i oko 527 nm) pripisane su postojanju RbCs molekularnih satelita u slučaju Rb-Cs mješavine. U slučaju K-Rb mješavine atomskih para pronađeno je nekoliko mogućih molekularnih satelita koji čekaju dodatne teorijske potvrde. Pojava ovih molekularnih satelita se u konačnici povezuje s fotoasocijacijom cezijevih i rubidijevih, odnosno kalijevih i rubidijevih atoma. Potvrda njihova postojanja je vrlo značajna zbog primjene u fizici ultrahladnih molekula. Kao zaključak svega navedenog, u budućnosti je moguće očekivati primjenu alkalijskih para, kako u domeni razvoja novih izvora svjetlosti, interakciji femtosekundnog laserskog frekventnog češlja s atomima kalija u magnetskom polju, tako i u domeni heteronuklearnih molekula s novim satelitskim vrpcama.The subject of this doctoral thesis is the application of hot alkali vapors. The thesis is composed of three parts each of which represents a certain application of alkali vapors. In the first part, properties, possible applications and improvements of cesium high pressure light source were studied. Furthermore, the comparison with properties of sodium high pressure light source was made. It was confirmed that cesium light source is, in a spectral aspect, ideal source of light giving that it has a spectrum very similar to the sun spectrum. However its poor efficiency, due to large infrared part of spectrum, has resulted in lack of its wide spread application. Additionally, within the scopes of this research, it was shown that the proportion of infrared part of the spectrum is considerably higher in cesium than in sodium high pressure light source, and that this proportion lowers with lowering voltage. Results of the measurements on the cesium high pressure light source presented in this dissertation could be used in creation of new light sources as well as in certain novel applications, such as generating electrical energy through the conversion of the sun light. The second part of the dissertation included realization of the experimental setup for velocity comb on potassium and theoretical simulation of this result. After previous realization of the femtosecond pulses interaction with the rubidium and cesium atoms, the same was achieved with potassium using the technique of modified direct frequency comb spectroscopy. The assumption that the excited states cannot be relaxed between two subsequent pulses of the femtosecond laser (period of repetition was 12,5 ns) was confirmed. Consequence of this is a change in the structure of the Doppler profile of potassium resonant spectral lines. The theoretical model has shown very good agreement with the experimental results which is of great importance for this method and further possible applications. The same experiment was performed in the homogenous magnetic field. These results could be used for application of potassium in magnetometry. The last part of the doctoral thesis is based on the measurement of absorption spectrum of alkali mixture of rubidium and cesium, or potassium and rubidium at different temperatures. At higher temperatures (higher than 450°C) new spectral phenomena was observed (at 418,3 nm and about 527 nm). They were attributed to molecular satellite of RbCs molecule in the Rb-Cs vapor mixture. In the case of K-Rb mixture several new possible satellites were found which needs theoretical confirmation. Appearance of these new satellites is related to photoassociation of cesium and rubidium, or potassium and rubidium atoms. Confirmation of their existence is very important for applications in physics of ultracold molecules. As an overall conclusion, it is possible to expect the application of alkali vapors in several areas; in the field of development of new light sources, interacting femtosecond laser frequency comb with potassium atoms in a magnetic field, as well as in the domain of heteronuclear molecules with new satellite bands

SSSL: Shoulder Surfing Safe Login

Classical PIN-entry methods are vulnerable to a broad class of observation attacks (shoulder surfing, key-logging). A number of alternative PIN-entry methods that are based on human cognitive skills have been proposed. These methods can be classified into two classes regarding information available to a passive adversary: (i) the adversary fully observes the entire input and output of a PIN-entry procedure, and (ii) the adversary can only partially observe the input and/or output. In this paper we propose a novel PIN-entry scheme- Shoulder Surfing Safe Login (SSSL). SSSL is a challenge response protocol that allows a user to login securely in the presence of the adversary who can observe (via key-loggers, cameras) user input. This is accomplished by restricting the access to SSSL challenge values. Compared to existing solutions, SSSL is both user-friendly (not mentally demanding) and cost efficient. Our usability study reveals that the average login time with SSSL is around 8 sec in a 5-digit PIN scenario. We also show the importance of considering side-channel timing attacks in the context of authentication schemes based on human cognitive skills

Application of Novel Lossless Compression of Medical Images Using Prediction and Contextual Error Modeling

Conduction of tele-3D-computer assisted operations as well as other telemedicine procedures often requires highest possible quality of transmitted medical images and video. Unfortunately, those data types are always associated with high telecommunication and storage costs that sometimes prevent more frequent usage of such procedures. We present a novel algorithm for lossless compression of medical images that is extremely helpful in reducing the telecommunication and storage costs. The algorithm models the image properties around the current, unknown pixel and adjusts itself to the local image region. The main contribution of this work is the enhancement of the well known approach of predictor blends through highly adaptive determination of blending context on a pixel-by-pixel basis using classification technique. We show that this approach is well suited for medical image data compression. Results obtained with the proposed compression method on medical images are very encouraging, beating several well known lossless compression methods. The predictor proposed can also be used in other image processing applications such as segmentation and extraction of image regions

Application of Novel Lossless Compression of Medical Images Using Prediction and Contextual Error Modeling

Conduction of tele-3D-computer assisted operations as well as other telemedicine procedures often requires highest possible quality of transmitted medical images and video. Unfortunately, those data types are always associated with high telecommunication and storage costs that sometimes prevent more frequent usage of such procedures. We present a novel algorithm for lossless compression of medical images that is extremely helpful in reducing the telecommunication and storage costs. The algorithm models the image properties around the current, unknown pixel and adjusts itself to the local image region. The main contribution of this work is the enhancement of the well known approach of predictor blends through highly adaptive determination of blending context on a pixel-by-pixel basis using classification technique. We show that this approach is well suited for medical image data compression. Results obtained with the proposed compression method on medical images are very encouraging, beating several well known lossless compression methods. The predictor proposed can also be used in other image processing applications such as segmentation and extraction of image regions

Reforma pravosuđa u Srbiji 2008-2012

U monografiji autori suočavaju pravničku javnost sa nedavnom pravnom istorijom neuspelih nastojanja da se pravosuđe u Srbiji pobolјša, da se poverenje građana povrati, da se postave osnove za vladavinu prava nad politikom, makar u najbitnijim elementima domena pravosudne vlasti, kao što je izbor sudija i javnih tužilaca, da se prikažu rezultati neuspele reforme i da se istraže pravni i politički uzroci neuspeha. Monografija je podelјena na dva dela – prvi pod nazivom „Reformisanje pravosuđa 2008–2010“, i drugi nazvan „Postupak preispitivanja 2011–2012“. Podela je kako hronološka, tako i logička – autori na sistematičan i sveobuhvatan način analiziraju ustavni i zakonski okvir reforme pravosuđa u Srbiji, kao i praksu tela koja su tu reformu sprovodila, te daju konačnu ocenu uspešnosti ovog poduhvata, koji je formalno okončan u julu 2012. godine. U prvom delu knjige se ispituje pravnoteorijski i pravnopolitički okvir onoga što se podrazumeva pod dobrim pravosuđem u jednoj demokratskoj državi, uz isticanje političke nezavisnosti sudija i sudstva kao klјučnog elementa te formule. Poseban deo posvećen je međunarodnopravnim, teorijskim, ustavnim i zakonskim osnovima reforme pravosuđa iz 2008. godine. U monografiji se detalјno kritički analizira Ustav Srbije iz 2006. godine, kao i Ustavni zakon za sprovođenje Ustava, te organizacioni pravosudni zakoni, koji su predstavlјali normativni osnov za najdublјi zahvat u pravosuđe u novoj demokratskoj istoriji Srbije. Detalјno su analizirane i odluke Ustavnog suda Srbije, kao i izdvojena mišlјenja. Ne manje značajna je i analiza odluke na osnovu koje je valјalo temelјno izmeniti pravosudni kadar Srbije. U radu se potom prikazuje način na koji su radila tela koja su reformu sprovodila, sa naročitim akcentom na sastav i način rada prvog saziva Visokog saveta sudstva, i na uočene nedostatke po oba pitanja. Potom je kritički analiziran normativnopravni okvir za postupak preispitivanja odluka prvih saziva Visokog saveta sudstva i Državnog veća tužilaca, kao uvod u drugi deo publikacije. Drugi deo monografije je posvećen detalјnoj kritičkoj analizi postupka preispitivanja odluka o neizboru na funkciju sudija, javnih tužilaca i zamenika javnih tužilaca. Autori su prvo detalјno prikazali rad tela pred kojima je vođen postupak, analizirajući naročito to da li su ona i u kojoj meri poštovala procesna načela u svom radu. Potom je izvršena detalјna analiza transparentnosti rada ovih tela i data ocena o tome da li su ona zaista bila nezavisna tela koja su postupala u cilјu ispravlјanja pogrešaka do tada učinjenih u reformi pravosuđa. Poseban deo publikacije posvećen je analizi sadržine odluka koje su usvojili novi sastavi Državnog veća tužilaca i Visokog saveta sudstva. Potom je učinjen osvrt na ulogu različitih organizacija koje su pratile ovaj postupak i njihov uticaj na tok postupka preispitivanja. Na samom kraju analizirane su odluke Ustavnog suda iz jula 2012. godine, kojima je postupak de facto vraćen u fazu pre opšteg izbora sudija, javnih tužilaca i zamenika javnih tužilaca iz 2009. godine. U zaklјučku su autori dali oštru ali utemelјenu kritiku pokušaja da se pravosuđe Srbije reformiše u skladu sa evropskim standardima, kao i neke načelne preporuke koje se moraju poštovati kako bi se postigao cilј kojem jedna demokratska država mora težiti – da ima odista nezavisno i stručno pravosuđe

Mjerna točnost stomatoloških radiometara ovisno o vremenu mjerenja

Inadequate intensity of the polymerization light source can compromise the quality and longevity of dental composite restorations. In order to maintain optimal strength of polymerization devices, regular control of polymerization units is necessary. The aim of this study was to compare the accuracy of two radiometers in the measurement of light intensity of photopolymerization devices concerning the time point of measurement. Light intensity measurements of 16 halogen and 8 LED curing lights were performed using three different devices at the beginning as well as 10 and 40 seconds after the start of illumination. Two were handheld radiometers: Bluephase meter (BM) and Cure Rite (CR), while an integrating sphere (IS) represented the reference device. Data were statistically analyzed using Friedman’s test and Wilcoxon signed-rank test (p<0.05). The values at the beginning and after 10 seconds measured by BM were significantly higher than the measurements by IS, whereas CR showed higher values after 10 and 40 seconds. Both commercial radiometers tended to overestimate the light intensity of LED and halogen curing units when compared to the reference device. The time point of measurement influences the output value. The heating of radiometers was proposed as a possible explanation for the inaccuracy.Neodgovarajući intenzitet svjetlosti polimerizacijskih uređaja može ugroziti kvalitetu i dugotrajnost stomatoloških kompozitnih restoracija. Kako bi se očuvala optimalna snaga polimerizacijskih uređaja neophodna je redovita kontrola. Svrha ovoga ispitivanja bila je usporediti dva radiometra u točnosti mjerenja intenziteta svjetlosti fotopolimerizacijskih uređaja uzimajući u obzir vrijeme mjerenja. Mjerenja intenziteta svjetlosti 16 halogenih i 8 LED polimerizacijskih lampa provedena su pomoću tri uređaja na početku iluminacije, te nakon 10 i 40 sekunda. Korištena su dva ručna radiometra: Bluephase meter (BM) i Cure Rite (CR), dok je integrirajuća sfera (IS) predstavljala referentni uređaj. Podaci su statistički analizirani pomoću Friedmanova testa i Wilcoxonova signed-rank testa (p<0.05). Vrijednosti izmjerene pomoću BM na početku i nakon 10 sekunda bile su značajno više od onih izmjerenih pomoću IS, dok je CR pokazao više vrijednosti nakon 10 i 40 sekunda. Oba komercijalno dostupna radiometra pokazala su tendenciju prikazivanja viših vrijednosti intenziteta svjetlosti LED i halogenih polimerizacijskih uređaja u usporedbi s referentnim uređajem. Vrijeme mjerenja ima utjecaja na očitanje intenziteta svjetlosti. Zagrijavanje radiometara je predloženo kao moguće objašnjenje njihove nepreciznosti

Laparoskopska parcijalna pericistektomija ehinokokne ciste slezene – prikaz bolesnice [Laparoscopic partial pericystectomy of splenic hydatid cyst - a case report]

Echinococcal cyst of the spleen is usually a result of infection with the parasite Echinococcus granulosus. The spleen is the third most frequent localization of echinococcus after liver and lungs. Partial laparoscopic pericystectomy can be done without the loss of blood and scattering of scolexes with spleen preservation and conservation of its immune function. We present the patient with a large (1 8 x 16 x 12 cm) echinococcal cyst of the spleen that compressed the surrounding organs (stomach, transverse colon, pancreas and left kidney), and prevented normal passage causing vomiting after every meal. In this patient, PAIR procedure (puncture, aspiration, injection, reaspiration) and conservative treatment was attempted on several occasions without success. Finally, laparoscopic partial pericystectomy was performed, evacuating the contents of the cyst. The surgery lasted 120 minutes. Postoperatively the patient was without complications. Hospitalization lasted five days. Six months later, the patient is without problems. These echinococcus cysts of the spleen cannot be solved using PAIR technique and conservative treatment. Laparoscopic partial pericystectomy is a better solution than open surgery due to less trauma to the patient, especially in elderly people

LAPAROSCOPIC PARTIAL PERICYSTECTOMY OF SPLENIC HYDATID CYST – A CASE REPORT

Ehinokokna cista slezene redovito je posljedica infekcije parazitom Echinococcus granulosus. Slezena je treća najčešća lokalizacija ehinokoka, nakon jetre i pluća. Parcijalna laparoskopska pericistektomija može se učiniti bez gubitka krvi i rasapa skoleksa s prezervacijom slezene i očuvanjem njezine imunosne funkcije. Prikazana je pacijentica s velikom (18 × 16 × 12 cm) ehinokoknom cistom slezene koja je pritiskala okolne organe (želudac, poprečni kolon, pankreas i lijevi bubreg), onemogućavajući normalnu pasažu i izazivajući povraćanje nakon svakog obroka. Kod bolesnice su u nekoliko navrata neuspješno pokušani postupak PAIR (punkcija, aspiracija, injekcija, reaspiracija) i konzervativno liječenje te je naposljetku učinjena laparoskopska parcijalna pericistektomija s evakuacijom sadržaja ciste. Zahvat je trajao 120 minuta. Postoperacijski tijek protekao je bez komplikacija. Hospitalizacija je trajala 5 dana. Šest mjeseci kasnije bolesnica je bez tegoba. Ovakve ehinokokne ciste slezene nije moguće ukloniti tehnikom PAIR i konzervativnim liječenjem. Laparoskopska parcijalna pericistektomija bolje je rješenje od otvorene operacije zbog manje traume za organizam, osobito kod starijih ljudi.Echinococcal cyst of the spleen is usually a result of infection with the parasite Echinococcus granulosus. The spleen is the third most frequent localization of echinococcus after liver and lungs. Partial laparoscopic pericystectomy can be done without the loss of blood and scattering of scolexes with spleen preservation and conservation of its immune function. We present the patient with a large (18×16×12 cm) echinococcal cyst of the spleen that compressed the surrounding organs (stomach, transverse colon, pancreas and left kidney), and prevented normal passage causing vomiting after every meal. In this patient, PAIR procedure (puncture, aspiration, injection, reaspiration) and conservative treatment was ­attempted on several occasions without success. Finally, laparoscopic partial pericystectomy was performed, evacuating the contents of the cyst. The surgery lasted 120 minutes. Postoperatively the patient was without complications. Hospi­talization lasted five days. Six months later, the patient is without problems. These echinococcus cysts of the spleen cannot be solved using PAIR technique and conservative treatment. Laparoscopic partial pericystectomy is a better solution than open surgery due to less trauma to the patient, especially in elderly people

LAPAROSCOPIC PARTIAL PERICYSTECTOMY OF SPLENIC HYDATID CYST – A CASE REPORT

Ehinokokna cista slezene redovito je posljedica infekcije parazitom Echinococcus granulosus. Slezena je treća najčešća lokalizacija ehinokoka, nakon jetre i pluća. Parcijalna laparoskopska pericistektomija može se učiniti bez gubitka krvi i rasapa skoleksa s prezervacijom slezene i očuvanjem njezine imunosne funkcije. Prikazana je pacijentica s velikom (18 × 16 × 12 cm) ehinokoknom cistom slezene koja je pritiskala okolne organe (želudac, poprečni kolon, pankreas i lijevi bubreg), onemogućavajući normalnu pasažu i izazivajući povraćanje nakon svakog obroka. Kod bolesnice su u nekoliko navrata neuspješno pokušani postupak PAIR (punkcija, aspiracija, injekcija, reaspiracija) i konzervativno liječenje te je naposljetku učinjena laparoskopska parcijalna pericistektomija s evakuacijom sadržaja ciste. Zahvat je trajao 120 minuta. Postoperacijski tijek protekao je bez komplikacija. Hospitalizacija je trajala 5 dana. Šest mjeseci kasnije bolesnica je bez tegoba. Ovakve ehinokokne ciste slezene nije moguće ukloniti tehnikom PAIR i konzervativnim liječenjem. Laparoskopska parcijalna pericistektomija bolje je rješenje od otvorene operacije zbog manje traume za organizam, osobito kod starijih ljudi.Echinococcal cyst of the spleen is usually a result of infection with the parasite Echinococcus granulosus. The spleen is the third most frequent localization of echinococcus after liver and lungs. Partial laparoscopic pericystectomy can be done without the loss of blood and scattering of scolexes with spleen preservation and conservation of its immune function. We present the patient with a large (18×16×12 cm) echinococcal cyst of the spleen that compressed the surrounding organs (stomach, transverse colon, pancreas and left kidney), and prevented normal passage causing vomiting after every meal. In this patient, PAIR procedure (puncture, aspiration, injection, reaspiration) and conservative treatment was ­attempted on several occasions without success. Finally, laparoscopic partial pericystectomy was performed, evacuating the contents of the cyst. The surgery lasted 120 minutes. Postoperatively the patient was without complications. Hospi­talization lasted five days. Six months later, the patient is without problems. These echinococcus cysts of the spleen cannot be solved using PAIR technique and conservative treatment. Laparoscopic partial pericystectomy is a better solution than open surgery due to less trauma to the patient, especially in elderly people