Predicting phase transition pressure in solids: a semiclassical possibility

This is a short review of the physical ideas,algorithm for calculations and some results of a semiclassical theory of the behaviour of materials under high pressure,proposed by P.Savic and R.Kasanin.The theory has found applications from DAC experiments to studies of planetary interior structure.Comment: PDF file,no figure

Avian Influenza - a global threat

Influenca ptica, popularno nazivana i ptičja gripa, uzrokuje velike štete u peradarstvu na Dalekom Istoku, ali i zabrinutost globalnih razmjera zbog širenja ovog virusa divljim pticama. Osim Dalekog Istoka, influenca ptica u protekle je dvije godine ćinila značajne probleme i u peradarstvu SAD-a, Kanade i Južnoafričke Republike. Do unatrag 10-ak godina nije bilo dokaza da virusi ptičje influnce mogu izravno zaraziti čovjeka i obratno. Izravni prijenos virusa influence s ptica na čovjeka prvi put je zapažen tijekom pojave visokopatogene influence u Hong Kongu 1997. uzrokovane podtipom virusa H5N1 kada je zaraženo 18, a umrlo 6 ljudi. Krajem 2003. na Dalekom Istoku ponovno izbija visokopatogena influenca te je po treći put od 1997. u ovoj regiji prouzročena podtipom H5N1. Zadnja od ove tri epizootije je započela u Južnoj Koreji i ubrzo se proširila u većini zemalja Dalekog Istoka. Za razliku od predhodnih pojava visokopatogene influence ptica, ovaj put virus prenose i divlje ptice te je zaraza do sada prenešena u većinu azijskih i europskih zemalja te u Afriku. Za očekivati je da će se bolest pojaviti i na drugim kontinentima. Najveću zabrinutost ipak je izazivalo zaražavanje ljudi sa smrtnošću od preko 50 %, kao i mogućnost da virus mutacijom stekne svojstvo interhumanog prijenosa što bi za posljedicu imalo novu pandemiju gripe.Avian influenza, also known as bird flu, causes enormous economic losses in poultry industry in the Far East, but also a global concern because of the spread of the virus by feral birds. Beside the Far East, avian influenza recently caused significant problems in poultry industry in the United States, Canada and South Africa. Until a decade ago, there was no evidence of spreading of the virus from birds to humans and vice versa. First direct transmission from birds to humans was reported in 1997 during an outbreak of highly pathogenic avian influenza in Hong Kong caused by H5N1 virus when 18 people became infected and six died. By the end of 2003 there was another outbreak of highly pathogenic avian influenza in the Far East and this was the third time in the region that it was caused by H5N1 subtype. The last H5N1 epidemic started in South Korea and soon spread to most Far East countries. In contrast to previous highly pathogenic avian influenza outbreaks, this time the virus was spread by feral birds and the infection was introduced in most of the Asian and European countries as well as in Africa. Nevertheless, the main concern is human infection with mortality above 50 % and possibility of the virus to mutate in a form capable for inter human transmission, which will result in new human influenza pandemic

"Thermal diffusivity and electron transport properties of NTC samples obtained by photoacoustic method

Poster presented at the Seventh Yugoslav Materials Research Society Conference - YUCOMAT 2005, Herceg Novi, Crna Gora, September 12-16, 2005

Ecological analysis of macrozoobenthos communities in the Nišava River

Doktorska disertacija obuhvata ekološku analizu zajednica makrozoobentosa reke Nišave i njihovu zavisnost od biotičkih i abiotičkih faktora. Istraživanja su obavljena mesečnom dinamikom na dvanaest lokaliteta od maja 2006. do aprila 2007. godine. U disertaciji se diskutuje zavisnost koncentracije hlorofila a i mase perifitona od abiotičkih faktora. Sa druge strane, razmatran je pritisak (na osnovu brojnosti) filtratornih vrsta zajednice makroinvertebrata na količinu fitoplanktona (izraženu preko hlorofila a) i pritisak grebača na masu perifitona. Dobijen je predikcioni model za izračunavanje koncentracije hlorofila a korišćenjem multiple linearne regresije. Model ima značajnu predikcionu moć (sig=0,003). Na osnovu Pirsonovog koeficijenta korelacije konstatovano je da postoji značajna povezanost koncentracije hlorofila a sa mutnoćom (p=0,000), sa ukupnim fosforom (p=0,029) i sa kombinovanom (zbirnom) koncentracijom ukupnog azota i fosfora (p=0,036). Nije utvrđena značajna povezanost sa brojnošću filtratornih organizama, što govori da njihov pritisak nije dovoljno jak da bi limitirao količinu fitoplanktona. Taksonomskom analizom makroinvertebrata reke Nišave utvrđeno je prisustvo 132 vrste iz 4 različita filuma. Filum Platyhelminthes je predstavljen sa 3 vrste iz 2 familije. Filum Annelida obuhvata 23 vrste iz 6 familija. Najveći broj vrsta ovog filuma pripada potklasi Oligochaeta (16 vrsta). Filum Mollusca obuhvata 13 vrsta iz 5 familija, od kojih 11 pripada klasi Gastropoda, a 2 klasi Bivalvia. Najveći broj vrsta faune makroinvertebrata pripada filumu Arthropoda (92 vrste iz 33 familije), od kojih 3 pripadaju subfilumu Crustacea, a sve ostale podfilumu Hexapoda, odnosno klasi Insecta. Rezultati taksonomske analize pojedinačnih grupa u okviru zajednice makroinvertebrata pokazuju da najveći broj vrsta pripada grupi Ephemeroptera (28 vrsta), zatim slede Diptera (26 vrsta) i Trichoptera (20 vrsta). Ostale grupe su zastupljene sa manjim brojem vrsta. Diskutovana je sezonska i longitudinalna dinamika grupa makroinvertebrata i njihova uslovljenost faktorima sredine. Razmatrani su indeksi diverziteta i adekvatnost njihovog korišćenja kao pokazatelja zagađenosti ekosistema, posebno za svaku grupu...This doctoral dissertation comprises the ecological analysis of macrozoobenthos communities in the Nišava River and their dependence on biotic and abiotic factors. The studies followed the monthly dynamics at 12 sites, from May 2006 to April 2007. The dissertation is discussing the dependence of chlorophyll a concentration and periphyton mass on abiotic factors, as well as the pressure (based on abundance) of filtrating species in the macroinvertebrate community on the amount of phytoplankton (expressed as chlorophyll a) and pressure of scraper species on periphyton mass. The prediction model for calculating chlorophyll a concentration was derived from the multiple linear regression. This model has a significant prediction power (sig=0.003). The Pearson's correlation coefficient was used to determine the correlation of chlorophyll a concentration with water turbidity (p=0.000), total phosphorus (p=0.029) and combined (summative) concentration of total nitrogen and total phosphorus (p=0.036). No significant connection with the abundance of filtrating organisms was determined, which indicates that their pressure was not strong enough to limit the quantity of phytoplankton. The taxonomic analysis of macroinvertebrates in the Nišava River yielded the presence of 132 species from 4 different phyla. The phylum Platyhelminthes was represented with 3 species from 2 families. The phylum Annelida was represented with 23 species from 6 families. Most recorded species from this phylum belong to the subclass Oligochaeta (16 species). The phylum Mollusca was represented with 13 species from 5 families, of which 11 were from the class Gastropoda and 2 from the class Bivalvia. Most species of the macroinvertebrate fauna belong to the phylum Arthropoda (92 species from 33 families), of which 3 were from the subphylum Crustacea, while all others belong to the subphylum Hexapoda and class Insecta. The results of the taxonomic analysis of individual groups within the macroinvertebrate community have shown that most species belong to the group Ephemeroptera (28 species), followed by Diptera (26 species), and Trichoptera (20 species). Other groups were represented with a smaller number of species. The study also includes the discussion on seasonal and longitudinal dynamics of macroinvertebrate groups and the effect of environmental factors on their presence. The diversity indices and their suitability as indicators of ecosystem pollution were discussed for each group separately..

Nucleotide sequence analysis of the inversion termini located within IS3 elements α3β3 and β5α5 of Escherichia coli K-12

This paper presents the first detailed structural analysis of termini of an inversion mediated by recombination between Escherichia coli native IS elements. The complete nucleotide sequence of the inversion termini in the lactose region of Escherichia coli K-12 confirms our previous suggestion that the inversion occurred by homologous recombination between α3β3 and β5α5 IS3 elements (D.J. Savic, J. Bacteriol. 140:311-319, 1979; D.J. Savic, S. Romac, and S.D. Ehrlich, J. Bacteriol. 155:943-946, 1983). The data show a slight structural divergence of α3β3 and β5α5 elements, but they do not reveal new sequences within recomhined IS3 elements that could influence the expression of nearby genes

Investigation of sintering kinetics of NiO using photo acoustic spectroscopy

Sintering kinetics of NiO was investigated using photo acoustic spectroscopy This method was used to follow the change of phase and amplitude of the photo acoustic signal of nickel-oxide samples sintered at 1373 K for 15-240 min. as a function of modulation frequency of the laser beam. Fitting of experimental data enabled determination of photo acoustic properties including thermal diffusivity of sintered nickel-oxide. Analysis of the change of sample density during sintering showed that the sintering process of this material can be observed from the view

Spectroscopy and polarimetry of the gravitationally lensed quasar Q0957+561

We present new spectroscopic and polarimetric observations of the first discovered gravitational lens Q0957+561 obtained with the 6m telescope of the Special Astrophysical Observatory (SAO, Russia). We explore spectropolarimetric parameters of Q0957+561 A,B components to investigate the innermost structure of the quasar, and explore the nature of polarization in lensed quasars. Additionally, we compare their present-day spectral characteristics with previous observations in order to study long-term spectral changes. We analyze spectral characteristics of lensed quasar comparing spectra of A and B images, as well as comparing previously observed image spectra with present-day ones. The polarization parameters of A-B images are compared. We also model the macro-lens influence on the polarization of the images representing the gravitational lens with a singular isothermal elliptical potential. We find that the brightness and SED ratio of components A and B changed during a long period. Polarization in broad lines of components A and B showed that the equatorial scattering cannot be detected in this quasar. We find wavelength-dependent polarization that may be explained as a combination of the polarization from the disc and outflowing material. There is a significant difference between polarization parameters of the A and B images: the B component shows a higher polarization degree and polarization angle. However, both polarization vectors are nearly perpendicular to the observed radio jet projection. It indicates that the polarization in the continuum is coming from the accretion disc. Our simple lensing model of a polarized source showed that macro-lens can cause the observed differences in polarization parameters of Q0957+561 A,B images. Using Mg II broad line and luminosity of component A we estimated that the Q0957+561 black hole mass is M~(4.8-6.1) $10^8$ M$\odot$Comment: accepted in A

"Thermal diffusivity and electron transport properties of NTC samples obtained by photoacoustic method

Poster presented at the Seventh Yugoslav Materials Research Society Conference - YUCOMAT 2005, Herceg Novi, Crna Gora, September 12-16, 2005