580 research outputs found
The Dark Matter equation of state through cosmic history
Cold Dark Matter (CDM) is a crucial constituent of the current concordance
cosmological model. Having a vanishing equation of state (EoS), its energy
density scales with the inverse cosmic volume and is thus uniquely described by
a single number, its present abundance. We test the inverse cosmic volume law
for Dark Matter (DM) by allowing its EoS to vary independently in eight
redshift bins in the range and . We use the latest measurements
of the Cosmic Microwave Background radiation from the Planck satellite and
supplement them with Baryon Acoustic Oscillation (BAO) data from the 6dF and
SDSS-III BOSS surveys, and with the Hubble Space Telescope (HST) key project
data. We find no evidence for nonzero EoS in any of the eight redshift bins.
With Planck data alone, the DM abundance is most strongly constrained around
matter-radiation equality (95%
c.l.), whereas its present day value is more weakly constrained (95% c.l.). Adding BAO or HST data does not
significantly change the constraint, while
tightens to (95% c.l.) and
(95% c.l.) respectively. Our results constrain for the first time the level of
"coldness" required of the DM across various cosmological epochs and show that
the DM abundance is strictly positive at all times.Comment: 6 pages, 4 figures, changed color scheme for figure
Znanje i stavovi beogradskih studenata medicine i stomatologije o upravljanju medicinskim otpadom
Introduction/Objective Knowledge and practical skills in medical waste (MW) management are of equal importance for medical and dental doctors. The first comparative study on the knowledge and skills in the field of MW management among Belgrade students was conducted with the goal of examining whether students of medicine and dentistry are equally familiar with this extremely important field. Methods a cross-sectional study included 558 students of the sixth year of studies (430 medical and 128 dental students) who completed an anonymous semi-structured questionnaire to determine attitudes and knowledge on MW management. Results the majority of medical and dental students had no training in MW management (79.5% and 74.6%, respectively). Dental students use protective equipment more frequently than medical students (94.5% vs. 42%, p lt 0.001). However, full vaccinal protection against hepatitis B is better among medical students compared to dental students (57.7% vs. 39.1%, p lt 0.001). Complete knowledge on postexposal prophylaxis is better among medical students compared to dental students (44.5% vs. 13.3%, p lt 0.001). However, dental students are more disciplined in reporting injuries (63.1% vs. 52.4%, p = 0.038). The students' knowledge on primary separation of infectious waste (93% vs. 77.8%, p lt 0.001) and used needles (80.3% vs. 70.4%, p = 0.007) is better among dental students compared to medical students' correct answers. Conclusion Dental students show better knowledge on MW management and are more disciplined in using personal infection protection compared to medical students. The students support continued training on MW management and investigations on this topic.Uvod/Cilj Znanje i praktične veštine upravljanja medicinskim otpadom su od posebnog značaja za doktore medicine i stomatologije. Komparativna studija o znanju i veštinama iz oblasti upravljanja medicinskim otpadom sprovedena je među beogradskim studentima prvi put, u cilju ispitivanja da li ovom izuzetno važnom oblašću studenti medicine i stomatologije vladaju podjednako dobro. Metode Ova studija preseka obuhvatila je 558 studenata šeste godine studija na Beogradskom univerzitetu (430 studenata medicine i 128 studenata stomatologije), koji su popunili anonimni upitnik o znanju i stavovima o upravljanju medicinskim otpadom. Rezultati Većina studenata stomatologije i medicine nisu imali nikakvu posebnu obuku iz upravljanja medicinskim otpadom (79,5% i 74,6%). Studenti stomatologije su češće koristili zaštitnu opremu (94,5% prema 42%, p lt 0,001). Vakcinalna zaštita od hepatitisa B je kompletnija među studentima medicine u odnosu na studente stomatologije (57,7% prema 39,1%, p lt 0,001). Znanje o profilaksi posle izloženosti bolja je među studentima medicine (44,5% prema 13,3%, p lt 0,001). Međutim, studenti stomatologije su ažurniji u pogledu prijavljivanja povreda na radnom mestu (63,1% prema 52,4%, p = 0,038). Znanje studenata o primarnoj separaciji infektivnog otpada i korišćenih igala je bolje među budućim stomatolozima (tačni odgovori 93% nasuprot 77,8%; p lt 0,001 i 80,3% prema 70,4%; p = 0,007). Zaključak Studenti stomatologije imaju bolje znanje o upravljanju medicinskim otpadom i disciplinovaniji su u pogledu korišćenja zaštitne opreme na radu u odnosu na studente medicine. Studenti podržavaju kontinuiranu edukaciju o upravljanju medicinskim otpadom i dalja istraživanja o ovoj temi
Roncus ivansticae (Neobisiidae, Pseudoscorpiones): A new epigean species from eastern Serbia
A single species of Roncus L. Koch, 1873, which was collected in eastern Serbia and is new to science (R. ivansticae n. sp.) is described herein; the diagnostic characters are illustrated and their distribution is provided. The possible establishment of two species (or supraspecific?) groups of Roncus is presented briefly in view of the importance of some diagnostic characters
Influence of shape complexity, material, Stress concentration and temperature To designing of welded constructions
U ovoj doktorskoj disertaciji zavarena konstrukcija je posmatrana kao
složen sistem elemenata sa kompleksnim interakcijama koji su heterogeni iz
aspekta materijala, oblika i dimenzija, mehaničkih karakteristika, kao i
eksploatacionih i funkcionalnih uslova. Heterogenost elemenata zavarene
konstrukcije uslovljava njihove različite karakteristike i odgovore na
opterećenje, dok nehomogenost njihove mikrostrukture uslovljava i dodatno
usložnjava naponsko-deformaciono stanje. Specifičnosti projektovanja
zavarenih mašinskih konstrukcija sagledane su iz aspekta složenosti oblika,
materijala, koncentracije napona i temperature eksploatacije. Eksperimentalno
određivanje mehaničkih karakteristika i analiza ponašanja u eksploatacionim
uslovima, na sobnoj i povišenim temperaturama, izvedena je na modelima od
mikrolegiranog čelika povišene jačine. Ispitivani modeli pored zone
zavarenog spoja sadrže i zonu geometrijskog diskontinuiteta kao dodatni izvor
koncentracije napona što je čest slučaj kod elemenata zavarenih konstrukcija.
Skup faktora koji uslovljavaju projektovanje zavarenih konstrukcija
identifikovan je sveobuhvatnom analizom eksperimentalnih rezultata i
verifikovan je teorijskim razmatranjem naponsko-deformacionog stanja koje
nastaje kod razmatranih modela. Posebna pažnja je posvećena analizi mehaničkih
osobina i karakteristika mikrolegiranih čelika povišene jačine za izradu
veoma odgovornih zavarenih mašinskih konstrukcija, kao savremenog materijala,
čija upotreba omogućava ostvarivanje niza prednosti, ali sa sobom donosi i
specifične probleme koji moraju biti adekvatno rešeni tokom procesa
projektovanja ovih konstrukcija.
Identifikovanjem faktora koji određuju konstrukciono rešenje zavarenih
mašinskih konstrukcija i utvrđivanjem njihovog uticaja date su preporuke
kojima se utemeljuje racionalno korišćenje materijala i energije, ostvaruje
smanjenje ukupnih troškova uz prihvatljive ekološke efekte i istovremeno
unapređuje sigurnost i pouzdanost zavarenih mašinskih konstrukcija.In this dissertation welded constructions are analyzed as complex systems of
elements with complex mechanisms of interactions that are heterogeneous from the
aspects of materials, shape and dimensions, mechanical properties, so as exploitation and
functional conditions. Heterogeneity of elements of welded constructions cause their
different characteristics and their different response to load, while inhomogeneity of their
microstructure cause complex stress-strain state so as additional complication of this
state. The specific characteristics of welded constructions design are highlighted from
the aspect of shape complexity, material, stress concentrations and exploitation
temperature. Experimental determination of mechanical properties and analysis of
mechanical response to load during exploitation at room and elevated temperatures were
done at models made of low alloyed high strength steel. Tested models besides zone of
welded joint have zone of geometrical discontinuities as additional source of stress
concentration that is common case at elements of welded mechanical constructions. Set
of parameters that influent to design of welded constructions is identificated by analysis
of experimental results and verified by theoretical considerations of stress-strain state at
tested models. Special focus is put on analysis of characteristics and mechanical
properties of low alloyed high strength steels for welded mechanical constructions as
present material with usage that obtain number of advances, but also bring some specific
problems that must be solved during process of design of those constructions.
By identification of factors that influent to constructional solution of welded
construction and determination of their influence, recommendations are given to
establish rational usage of material and energy, obtained reduction of total costs with
minimal ecological impact and with simultaneous improve of safety and reliability of
welded constructions
Revealing the nature of central emission nebulae in the dwarf galaxy NGC 185
In this paper we present new optical observations of the galaxy NGC 185
intended to reveal the status of supernova remnants (SNRs) in this dwarf
companion of the Andromeda galaxy. Previously, it was reported that this galaxy
hosts one SNR. Our deep photometric study with the 2m telescope at Rozhen
National Astronomical Observatory using narrow-band H and [SII] filters
revealed complex structure of the interstellar medium in the center of the
galaxy. To confirm the classification and to study the kinematics of the
detected nebulae, we carried out spectroscopic observations using the SCORPIO
multi-mode spectrograph at the 6m telescope at the Special Astrophysical
Observatory of the Russian Academy of Science, both in low- and high-resolution
modes. We also searched the archival X-ray and radio data for counterparts of
the candidate SNRs identified by our optical observations. Our observations
imply the presence of one more SNR, one possible HII region previously
cataloged as part of an SNR, and the presence of an additional source of shock
ionization in one low-brightness PN. We detected enhanced [SII]/H_alpha and
[NII]/H_alpha line ratios, as well as relatively high (up to 90 km s)
expansion velocities of the two observed nebulae, motivating their
classification as SNRs (with diameters of 45 pc and 50 pc), confirmed by both
photometric and spectral observations. The estimated electron density of
emission nebulae is 30 - 200 cm. Archival XMM-Newton observations
indicate the presence of an extended, low-brightness, soft source in projection
of one of the optical SNRs, whereas the archival VLA radio image shows weak,
unresolved emission in the center of NGC 185.Comment: 15 pages, 14 figures, accepted for publication in A&
The effect of VHL gene mutation on the expression levels of mTOR signaling pathway proteins in clear cell renal cell carcinoma
Sporadični svetloćelijski karcinomi bubrega asocirani su sa mutacijama tumor
supresorskog gena VHL kod 60-80 % pacijenata. U odsustvu funkcionalnog proteina
VHL dolazi do akumulacije faktora indukovanih hipoksijom koji regulišu ekspresiju
gena uključenih u procese angiogeneze, eritropoeze, ćelijskog metabolizma i
preživljavanja. Pored specifičnog genetičkog profila i povišenog nivoa HIF-2α
svetloćelijske karcinome bubrega karakteriše glikolitički metabolički put i povišena
aktivnost mTOR signalnog puta. Nepovoljan energetski status i hipoksija blokiraju
aktivnost mTOR signalnog puta preko proteina AMPK i REDD1.
Ova studija imala je za cilj da utvrdi mogću asocijaciju mutacionog statusa gena
VHL sa patohistološkim parametrima, nivoom HIF-2α iRNK i nivoom proteina HIF-2α,
mTOR, TSC1, TSC2, eIF4E-BP1, p70S6K1, AMPK, REDD1 i PDK3 u svetloćelijskom
karcinomu bubrega.
Studija je obuhvatala 47 pacijenata kojima je urađena totalna nefrektomija zbog
prisustva svetloćelijskog karcinoma bubrega. Genomska DNK izolovana iz uzoraka
venske krvi i somatska DNK izolovana iz uzoraka tumorskog i neizmenjenog tkiva
bubrega upotrebljene su za određivanje mutacionog statusa gena VHL i gubitka
heterozigotnosti 3p lokusa sekvenciranjem, metodom amplifikacije višestruko ligiranih
proba i fragmentnom analizom mikrosatelitnih markera. Metilacioni status promotora
gena VHL ispitan je metil specifičnom PCR reakcijom nakon bisulfitne modifikacije
DNK. Kvantitativni RT-PCR primenjen je za relativnu kvantifikaciju HIF-2α iRNK u
tumorskom i neizmenjenog tkivu bubrega. Kvantitafikacija ekspresije proteina HIF-2α,
mTOR, TSC1, eIF4E-BP1, p70S6K1, AMPK, REDD1 i PDK3 utvrđena je Western blot
metodom. Semikvantitativna imunohistohemijska analiza korišćena je za utvrđivanje
nivoa ekpresije proteina TSC2...Sporadic clear cell renal carcinoma is associated with mutations of the VHL gene
in 60-80 % patients. The absence of a functional VHL protein leads to accumulation of
hypoxia-inducible factors which regulate expression of genes involved in angiogenesis,
erythropoiesis, cell metabolism and survival. Specific genetic background,
overexpression of HIF-2α transcription factor as well as glycolytic metabolism and
upregulated activity of mTOR pathway are the main characteristics of clear cell renal
carcinoma. The lack of energy and hypoxia inhibit mTOR signaling through activity of
AMPK and REDD1 proteins.
The aim of present study was to determine association of VHL gene mutational
status with pathohistological parameters, expression level of mRNA HIF-2α and
expression levels of mTOR, TSC1, TSC2, eIF4E-BP1, p70S6K1, AMPK, REDD1 and
PDK3 proteins in clear cell renal carcinoma.
The study included 47 patients who underwent radical nephrectomy due to
unilateral kidney tumor. DNA was extracted from peripheral venous blood, tumorous
and corresponding healthy renal tissue. The VHL gene mutational status and loss of
heterozigosity of 3p loci were detected using DNA sequencing, MLPA and analysis of
microsatellite markers. The VHL gene promoter methylation analysis was examined by
MS-PCR after bisulphite modification of DNA. Quantitative real time PCR was
performed for relative quantification of HIF-2 alpha mRNA. Expression levels of HIF-
2α, mTOR, TSC1, eIF4E-BP1, p70S6K1, AMPK, REDD1 and PDK3 proteins was
determined using Western blot method. Immunohistochemistry was performed for semiquantitative
analysis of TSC2 protein.
Alteration of VHL gene and/or changes of 3p loci were detected in 37/47 (78.7
%) analysed tumorous samples..
The analysis of particles emission during the process of grinding of steel EN 90MNV8
Metal grinding is a one of the manufacturing technologies that is greatly connected to particles emission. Particles generated during the grinding process are dangerous in terms of its potential penetration deeply into the lungs of an operator. The level of risk for human respiratory system is related to nature, shape and size of the particles, and for this reason it is important to have a quality characterization of emitted particles. This paper focuses on particles characterization on the bases of image analysis from scanning electron microscopy (SEM). The research was conducted during the process of grinding of steel EN 90MnV8, using personal sampler. Results of image analysis, consisted of Feret’s diameter and circularity, showed quite a wide range of sizes and significant deviation of particles from regular shape
Specific purpose language teaching within the context of the European language education policy
Predmet ovog istraživanja je analiza postulata evropske obrazovne jezičke politike i rezultati koji se postižu primenom pojedinih njenih aspekata na planiranje nastave jezika struke/jezika za posebne namene. U radu su predstavljena teorijska i praktična saznanja iz primenjene lingvistike, teorije jezičke politike i planiranja i metodike nastave stranog jezika kao jezika struke/jezika za posebne namene. Pored toga, pravi se jasna razlika između jezika struke i jezika za posebne namene sa ciljem da se doprinese unapređenju terminološke preciznosti u ovoj oblasti primenjene lingvistike. Empirijski deo obuhvata akciono istraživanje bazirano na vlastitom iskustvu autorke u radu sa učenicima različitih struka i odnosi se na analizu efikasnosti primene preporuka Zajedničkog evropskog okvira za jezike u planiranju i nastavi jezika struke/jezika za posebne namene, uključivanja sociolingvističkih, interkulturnih i vanjezičkih elemenata u nastavu, kao i primene akcionog pristupa u nastavi jezika struke/jezika za posebne namene. U radu se prikazuje nekoliko inovativnih modela nastave francuskog jezika struke/jezika za posebne namene zasnovanih na ovim principima. Ispitanici su bili zaposleni u Ministarstvu pravde, pripadnici Ministarstva unutrašnjih poslova koji pohađaju specijalizovane tečajeve francuskog jezika u organizaciji Francuskog instituta u Beogradu i studenti Fakulteta bezbednosti Univerziteta u Beogradu koji pohađaju izbornu nastavu jezika struke u okviru Inovacionog centra Fakulteta bezbednosti. Pored toga, definisane su smernice za dalje unapređenje nastave jezika struke u našim visokoškolskim ustanovama a odnose se pre svega na učenje jezika struke od početnog nivoa, kreiranje programa nastave u skladu sa potrebama učenika i primenu adekvatnih metodoloških postupaka.The subject of this research work is an analysis of the premises of the European education policy, assessment of the results achieved through implementation of certain aspects of this policy and their impact on the planning of language teaching for vocational and specific purposes. The thesis presents theoretical and practical findings from the fields of applied linguistics, language policy and planning theory and foreign language teaching methodology for vocational and specific purpose language teaching. The thesis offers a clear distinction between the vocational language and specific purpose language, in order to achieve a higher level of terminological precision in this field of applied linguistics. The empirically based part of the thesis presents action based research results originating from the author’s personal experience in work with the students from a variety of vocational backgrounds and offers an assessment of the levels of efficiency achieved through practical implementation of the recommendations contained in the Common European Framework of Reference for Languages in the course of planning and realization of language teaching for vocational and specific purposes, inclusion of sociolinguistic, intercultural and extra linguistic elements in the teaching process, and implementation of the action based approach in language teaching for vocational and specific purposes. The thesis presents a number of innovative models of French language teaching for vocational and specific purposes based on these principles. The subjects were employees of the Ministry of Justice and Ministry of Interior Affairs who attended specialized language courses organized by the French Language Institute in Belgrade and students of the Faculty of Security of Belgrade University who attended elective language courses at the Innovation Centre of the Faculty of Security. Also, the thesis offers a set of guidelines for further improvement of the vocational language teaching at the institutions of higher education, focusing primarily on introduction of vocational language teaching in the early stages of language learning, starting from the beginner’s level, development of curricula that will meet the specific needs of the students and selection of appropriate teaching methods
Analysis of the correlation between socio-environmental factors and academic stress and mental health of students
Cilj: Mnogobrojni negativni faktori okruženja i psihosocijalni stresori, kao što su
konstantni pritisak za uspehom, preopterećenost akademskim obavezama i nedostatak
slobodnog vremena, a u današnje vreme i teška socijalno ekonomska situacija, doprinose
nastanku sve češćih poremećaja psihofizičkog zdravlja univerzitetskih studenata, te je
zdravlje ove populacije postalo fokus istraživanja poslednjih godina. Glavni ciljevi rada
sastoje se u ispitivanju specifičnosti zdravstvenog stanja studenata Medicinskog fakulteta,
Ekonomskog fakulteta i Fakulteta veterinarske medicine Univerziteta u Beogradu iz
podataka sistematskih pregleda Zavoda za zdravstvenu zaštitu studenata Beograd sa
posebnim osvrtom na mentalno zdravlje i analiza njihovog uspeha na studijama. Cilj rada
je i procena uticaja socio-ekoloških faktora na psihofizičko zdravlje studenata tri ispitivana
fakulteta, sa prospektivnim praćenjem uticaja ovih faktora kod studenata medicine. Kao
cilj je navedena i analiza stanja psihičkog distresa, analiza rezultata pojave sindroma
izgaranja (emocionalne iscrpljenosti, depersonalizacije i umanjenog samopostignuća) za
studente sva tri ispitivana fakulteta, kao i analiza prevalencije faktora rizika za nastanak
akademskog distresa i sindroma izgaranja na predkliničkim i kliničkim godinama studija
Medicinskog fakulteta u Beogradu. Metodologija: Ovo istraživanje je dizajnirano kao kombinacija dve studije – studije
preseka, koja predstavlja istraživanje prevalencije akademskog distresa i sindroma
izgaranja kod studenata ispitivana tri fakulteta u Beogradu i prospektivne studije, kojom
su obuhvaćeni studenti I i III godine Medicinskog fakulteta i tokom naredne II i IV godina
studija sa ciljem da se ispitaju promene u rezultatima pojave akademskog distresa i
sindroma izgaranja na predkliničkim i kliničkim godinama studija...Objective: Numerous negative environmental factors and psychosocial stressors, such as
constant pressure to succeed, excessive academic obligations and lack of free time, and in
the present time the difficult socioeconomic situation, contribute to the emergence of
increasingly frequent mental and physical health disorders in university students, making
the health of this population the focus of the recent research. The main objectives of this
work include the analysis of the specifics of the health status of students of the School of
Medicine, Faculty of Economics and the Faculty of Veterinary Medicine, University of
Belgrade based on the data of physical examinations conducted at the Institute for Student
Health Care Belgrade, with special emphasis on their mental health and academic
achievement. The aim is to estimate the impact of socio-environmental factors on
psychological and physical health of students of these three faculties, with the prospective
monitoring of the impact these factors have on medical students. Another goal is the
analysis of the mental distress, the analysis of the results of the occurrence of burnout
syndrome (emotional exhaustion, depersonalization and reduced personal accomplishment)
for students of all three faculties, as well as the analysis of the prevalence of risk factors for
academic distress and burnout syndrome in preclinical and clinical years of studies at the
School of Medicine in Belgrade.
Methodology: This study was designed as a combination of two studies - cross section,
which is a survey on the prevalence of academic distress and burnout syndrome among students studied at three universities in Belgrade and prospective studies, which included
students first and third year of the School of Medicine, and over the next two and four
years of study in order to examine the changes in the results of the occurrence of academic
distress and burnout syndrome in preclinical and clinical years of study..
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