Spin paramagnetism in d-wave superconductors

The Ginzburg-Landau equations are derived from the microscopic theory for clean layered superconductors with $d_{x^2-y^2}$ pairing symmetry, including the Pauli paramagnetism effect. The upper critical field $H_{c2}$ parallel to the $c$ axis is calculated. A comparison with the experimental data for YBCO suggests that, relative to the orbital effect, the Pauli paramagnetism contribution to $H_{c2}$ is significant. The reversible magnetization $M$ in high magnetic fields is also calculated, showing strong temperature dependence of the slope $dM/dH$, as a consequence of the spin paramagnetism. A simple expression for the high temperature spin susceptibility is derived, in a good agreement with the Knight shift measurements on YBCO.Comment: 8 pages, 3 figures; minor changes are included; reference 35 is added; shorter version will be published in Phys. Rev. B, scheduled issue 01 July 200

Cleaner metallurgical industry in Serbia: a road to the sustainable development

Since the sustainable development has been a global and fundamental objecttive, a metallurgical industrial sector faces some of the most difficult sustainability challenges of any industrial sector. On the other hand, the metallurgical production in Serbia is a very important part of the economy. Due to present facilities and technologies, metallurgical companies face a great challenge to fulfill the requirements introduced by legislature referring to the cleaner production and sustainable development. The state of art in the production, facilities, pollution with some answers to imposed challenges is presented

Dynamic polarization of graphene by moving external charges: random phase approximation

We evaluate the stopping and image forces on a charged particle moving parallel to a doped sheet of graphene by using the dielectric response formalism for graphene's $\pi$-electron bands in the random phase approximation (RPA). The forces are presented as functions of the particle speed and the particle distance for a broad range of charge-carrier densities in graphene. A detailed comparison with the results from a kinetic equation model reveal the importance of inter-band single-particle excitations in the RPA model for high particle speeds. We also consider the effects of a finite gap between graphene and a supporting substrate, as well as the effects of a finite damping rate that is included through the use of Mermin's procedure. The damping rate is estimated from a tentative comparison of the Mermin loss function with a HREELS experiment. In the limit of low particle speeds, several analytical results are obtained for the friction coefficient that show an intricate relationship between the charge-carrier density, the damping rate, and the particle distance, which may be relevant to surface processes and electrochemistry involving graphene.Comment: 14 pages, 10 figures, accepted for publication in Phys. Rev.

Meron ground states of quantum Hall droplets

We argue that topological meron excitations, which are in a strong coupling phase (bound in pairs) in infinite quantum Hall ferromagnets, become deconfined in finite size quantum Hall systems. Although effectively for larger systems meron energy grows with the size of the system, when gyromagnetic ratio is small meron becomes the lowest lying state of a quantum Hall droplet. This comes as a consequence of the many-body correlations built in the meron construction that minimize the interaction energy. We demonstrate this by using mean field ansatzes for meron wave function. The ansatzes will enable us to consider much larger system sizes than in the previous work [A. Petkovic and M.V. Milovanovic, PRL 98, 066808 (2007)], where fractionalization into merons was introduced.Comment: 6 pages, 6 figure

Breeding site traits of European newts (Triturus macedonicus, Lissotriton vulgaris, and Mesotriton alpestris: Salamandridae) in the Montenegrin karst region

We recorded the occurrence of three European newt species - the smooth newt (Lissotriton vulgaris), the eastern alpine crested newt (Triturus macedonicus), and the alpine newt (Mesotriton alpestris) - in the Montenegrin karst, as well as their breeding site characteristics. In terms of long-lasting breeding site numbers and occupation rate, the most common species is the smooth newt, followed by the alpine newt and the crested newt. The examined water bodies with­out newts showed no significant differences of aquatic habitat characteristics compared to water bodies with newts. The factors that explained most of the observed variation in newt breeding site traits were the habitat category and habitat origin. The alpine newt primarily inhabits natural lakes, while the crested newt inhabits artificial breeding sites such as lithotelma and ubao. The smooth newt is less choosy and occurs in different types of natural and artificial habitats. The aquatic requirements of Montenegrin newt species do not differ substantially in many respects from requirements of the core species range populations.Istraživano je prisustvo tri vrste evropskih mrmoljaka u crnogorskom karstu, malog (Lissotriton vulgaris), istočnog glavatog (Triturus macedonicus) i planinskog mrmoljka (Mesotriton alpestris), kao i karakteristike njihovih reproduktivnih staništa. U pogledu broja reproduktivnih staništa, mali mrmoljak je najčešća vrsta, zatim sledi planinski i na kraju istočni glavati mrmoljak. Istraživana vodena staništa bez mrmoljaka nisu pokazala značajne razlike u karakteristikama u poređenju sa vodenim staništima sa mrmoljcima. Faktori koji najbolje objašnjavaju uočenu varijabilnost karakteristika reproduktivnih staništa mrmoljaka su tip i poreklo staništa. Planinski mrmoljak primarno naseljava jezera prirodnog porekla, dok istočni glavati mrmoljak naseljava antropogena staništa (najčešće kamenice i ublove). Mali mrmoljak naseljava različite tipove staništa prirodnog ili antropogenog porekla. Osobine reproduktivnih staništa mrmoljaka Crne Gore ne razlikuju se umnogome od osobina reproduktivnih staništa populacija iz centra areala ovih vrsta.Projekat ministarstva br. 14305

Implementation of GIS technologies in assessment and protection of natural values of Tara National Park

Mount Tara is among the most important centers of Balkan and European ecosystem and species biodiversity. It is characterized by diversified and well-maintained communities of old deciduous and mixed coniferous forests (beech/fir/spruce). They represent a unique example of well preserved forests in SE Europe with numerous endemic and relict species of indigenous flora and fauna. The geographical information system (GIS) that we have created has proved an excellent tool for valorization and protection of all natural values and potentials of Tara National Park.Geografski informacioni sistem je: organizovan skup računarskog hardvera softvera, geografskih podataka i kadra, dizajniran da efikasno prikuplja smešta, nadgrađuje, manipuliše, analizira i prikazuje sve forme geografski referencirane informacije. Za ekologe GIS je otvorio nove mogućnosti za istraživanja i aplikaciju sakupljenih informacija. Zbog same kompleksnosti sistema životne sredine mi najčešće nastojimo da ih proučavamo koristeći redukcionistički pristup, fokusirajući ce na male, diskretne pojednostavljene aspekte. Međutim većina problema u životnoj sredini su više faktorijalni i zahtevaju razmatranje širokog spektra izvora informacija pitanja i interesa. Za većinu ekoloških studija potrebne su nam eksplicitnije i kvalifikovanije terenske informacije vezane za faktore koji bi mogli da objasne posmatranu ekosistemsku, faunističku i florističku raznovrsnost u dimenziji prostorne i vremenske distribucije uključujući i podatke o geologiji, klimi, pedologiji, distribuciji i ponašanju istrživanih vrsta. Ovde svoju ulogu pronalaze geografski informacioni sistemi (GIS). Nacionalni park Tara obuhvata najveći deo planine Tare u zapadnoj Srbiji prosečne nadmorske visine 1000-1200 m na 180 km od Beograda. Ukupna površina zaštićenog područja Nacionalnog parka je 19.175 ha, a 37.584 ha predstavlja zaštitnu zonu oko Nacionalnog parka. Pripada opštini Bajina Bašta. Planina Tara predstavlja jednu od vrućih tačaka specijskog i ekosistemskog diverziteta sa 35 različitih šumskih zajednica lišćarskog, mešovito četinarskog tipa, kao i 19 opisanih livadskih zajednica. Mnoge od njih posebno one sa Pančićevom omorikom, imaju reliktan ili endemoreliktan karakter. U tom smislu sasvim je opravdano što se Tara danas našla na listi područja značajnih za očuvanje ptičijeg sveta (IBA) i dnevnih leptira Evrope (PBA), a u toku je njeno uključivanje u međunarodnu listu područja značajnog za očuvanje svetske flore (IPA). Kako se gazdovanje i upravljanje praktično svim prirodnim potencijalima NP Tara, do sada dominantno zasnivalo na principima šumarske tehnologije i inženjeringa ovaj rad ima svoju punu naučnu opravdanost u pokušaju implementacije savremenih naučnih saznanja iz oblasti zaštite biodiverziteta, konzervacione ekologije geografije i prostornog planiranja u mehanizam upravljanja prirodnim nacionalnim resursima. Ovaj tip vrednovanja i zaštite otvara mogućnost primene održivog/usklađenog korišćenja resursa NP Tara. Tokom 2002. i 2003. godine formirane su teme GIS NP Tara koje obuhvataju prirodne (geomorfologija, geologija, pedologija, hidrologija, vegetacija, flora fauna), korišćene (eksploatacija šuma) i veštačke (antropogene) sadržaje (puteve, brane, naselja, turističke sadržaje i granice). Geografski informacioni sistem koji je formiran za NP Taru sa temama koje ga čine da prati okvire sličnih projekata rađenih u Evropi i svetu i jedan je od tipičnih geografskih informacionih sistema (iz oblasti ekologije, zaštite životne sredine, šumarstva, itd), koji sadrži gotovo sve vrste podataka (izuzev satelitskih snimaka) u GIS (rasterske, vektorske, DEM, baza podataka i aerofotogrametrijske snimke).Projekat ministarstv

Genetic Variability in Different Lucerne (\u3cem\u3eMedicago Sativa\u3c/em\u3e) Genotypes

One of the basic goals of modern lucerne breeding programmes is creation of new cultivars with a great potential for high quality and stable yields of both forage and hay (Riday & Brummer, 2002). Such cultivars meet increased needs of animal husbandry and must contribute to diverse farming systems (Luki , 2000). Our trial was aimed at determining genetic variability of yield components in 7 lucerne genotypes, as well as at evaluation of their breeding potential as gene donors to new lucerne cultivar

Subwavelength hole arrays with nanoapertures fabricated by scanning probe nanolithography

Owing to their surface plasmon-based operation, arrays of subwavelength holes show extraordinary electromagnetic transmission and intense field localizations of several orders of magnitude. Thus they were proposed as the basic building blocks for a number of applications utilizing the enhancement of nonlinear optical effects. We designed and simulated nanometer-sized subwavelength holes using an analytical approach. In our experiments we used the scanning probe method for nanolithographic fabrication of subwavelength hole arrays in silver layers sputtered on a positive photoresist substrate. We fabricated ordered nanohole patterns with different shapes, dispositions and proportions. The smallest width was about 60 nm. We characterized the fabricated samples by atomic force microscopy

Bistability in superconducting rings containing an inhomogeneous Josephson junction

We investigate the magnetic response of a superconducting Nb ring containing a ferromagnetic PdNi Josephson junction and a tunnel junction in parallel. A doubling of the switching frequency is observed within certain intervals of the external magnetic field. Assuming sinusoidal current-phase relations of both junctions our model of a dc-SQUID embedded within a superconducting ring explains this feature by a sequence of current reversals in the ferromagnetic section of the junction in these field intervals. The switching anomalies are induced by the coupling between the magnetic fluxes in the two superconducting loops.Comment: 5 pages, 4 figure