Birational automorphism groups of projective varieties of Picard number two

We slightly extend a result of Oguiso on birational or automorphism groups (resp. of Lazi\'c - Peternell on Morrison-Kawamata cone conjecture) from Calabi-Yau manifolds of Picard number two to arbitrary singular varieties X (resp. to klt Calabi-Yau pairs in broad sense) of Picard number two. When X has only klt singularities and is not a complex torus, we show that either Aut(X) is almost cyclic, or it has only finitely many connected components.Comment: title slightly changed to this; some proof simplified; submitted to the Proceedings of Groups of Automorphisms in Birational and Affine Geometry, 28 October - 3 November 2012, C.I.R.M., Trento, Ital

Numerical analysis of temperature field during hardfacing process and comparison with experimental results

The three-dimensional transient nonlinear thermal analysis of the hard facing process is performed by using the finite element method. The simulations were executed on the open source Salome platform using the open source finite element solver Code_Aster. The Gaussian double ellipsoid was selected in order to enable greater possibilities for the calculation of the moving heat source. The numerical results were compared with available experimental results

Impact of general anesthesia on sleep in the experimental model of Parkison's disease neuropathology - possible risks of postoperative recovery

U ovoj doktorskoj disertaciji ispitivan je uticaj ketamin/diazepam i pentobarbital opšte anestezije na EEG mikrostrukturu i obrazac disanja tokom anestezije, kao i na arhitekturu spavanja i strukturu prelaznih stanja, EEG mikrostrukturu i dinamiku epizoda svih faza spavanja nakon anestezije, kako u fiziološkim kontrolama, tako i u eksperimentalnom modelu holinergičke neuropatologije Parkinsonove bolesti (bilateralna lezija PPT jedra). Rezultati ove doktorske disertacije pokazali su da je ketamin/diazepam anestezija operativnog nivoa izazvala ozbiljan poremećaj respiratornog obrasca i EEG mikrostrukture tokom anestezije. Međutim, jednako vreme potrebno za uspostavljanje stabilne anestezije u pacova sa bilateralnom lezijom PPT jedra kao i dugotrajni suprimirajući efekti na povećanu NREM beta i teta amplitudu (elektrofiziološki markeri deficita holinergičkih neurona PPT jedra) nakon anestezije, ukazuju da je ova anestezija potencijalno povoljnija, kako za ulazak u anesteziju, tako i za NREM fazu spavanja nakon operativnih zahvata kod gerijatrijskih pacijenata, kao i pacijenata obolelih od Parkinsonove i Alchajmerove bolesti. Nasuprot ketamin/diazepam anesteziji, pentobarbital anestezija ima povoljnije dejstvo na REM fazu spavanja nakon anestezije, kako kod fizioloških kontrola, tako i u eksperimentalnom modelu holinergičke neuropatologije Parkinsonove bolesti na osnovu: dugotrajnih poremećaja REM spavanja i strukture prelaznih stanja kod fizioloških kontrola koje izaziva ketamin/diazepam anestezija; suprimirajućih efekata obe anestezije operativnog nivoa na produženu REM/REM1 fazu spavanja i poremećaj njihove EEG mikrostrukture kod bilateralne lezije PPT jedra; suprimirajućeg efekta pentobarbital anestezije na povećani broj NREM/REM/NREM prelaza uzrokovanih lezijom PPT jedra; kao i na osnovu EEG mikrostrukture tokom stabilne pentobarbital anestezije, koja se ne razlikuje u poređenju PPT lezije i fiziološke kontrole

Kvazi-klasična osnovna stanja i magnoni u monoperiodičnim spinskim sistemima

Tema ovog rada je simetrijski zasnovana analiza sistema čiji atomi (čvorovi) imaju nenulte magnetne momente (spinove), a čija je dinamika diktirana Hamiltonijanima kvadratne forme po spinovima, tj. spin-spin interakcija je zadata tenzorom drugog reda. U ovoj oblasti se obično koristi isključivo translaciona periodi ˇcnost kristala, dok se ostale simetrije naknadno razmatraju. Stoga je osnovni cilj ove studije uključivanje kompletne simetrije sistema, pre svega u modeliranje magnetnih Hamiltonijana, a potom i u nalaženje njihovih mogućih rešenja u smislu kvazi-klasičnih osnovnih stanja i odgovarajućih nisko-energijskih (heli)magnonskih spektara. Da bi se to efikasno postiglo, rad je metodološki zasnovan na strogom formalizmu koji tretira sisteme čije su geometrijske konfiguiracije invarijantne na podgrupe Euklidske grupe, a interakcije obuhvataju proizvoljan nivo susedstva. Polazeći od osobina Lijeve algebre ugaonih momenata, u kvantno-mehaničkom prostoru stanja definiše se dejstvo grupe, koje, usled principa invarijantnosti hamiltonijana, izdvaja aksijalno-vektorsku reprezentaciju uz odgovarajuća ograničenja na tenzorsko polje interakcije. Zajedno sa tim, hermitičnost hamiltonijana omogućava generalizaciju Morijinih pravila na sve dozvoljene komponente interakcije. Zbog velike dimenzije kvantnog prostora stanja, koja se skalira eksponencijalno sa brojem čvorova, rešenja ovakvih modela su, osim u najjednostavnijim slučajevima, aproksimativna. Tako, ograničavanjem probnog skupa varijacionog problema na separabilna stanja energija postaje funkcional po klasičnim vektorima (na čvorovima), koji, u opštem slučaju, nemaju med¯usobno jednake dužine. Kako je potonji uslov podrazumevan u aproksimaciji srednjeg polja, u radu se razmatraju mogu´cnosti da ovako nad¯eno osnovno stanje bude regularno, tj. invarijantno na neku spinsku grupu. U tu svrhu se pokazuje da se klasifikacija spinskih grupa može izvršiti korišćenjem realnih trodimenzionalnih reprezentacija (spinske reprezentacije) kojima se direktno određuju i sva regularna uređenja (međusobno jednakih dužina). Polazeći dalje od pretpostavke da je model takav da je optimizovan regularno ured¯enim klasičnim spinovima na ˇcvorovima, a ˇcuvaju´ci njihovu prirodu ugaonog momenta, izvedeno je preslikavanje u bozonsku sliku otklona od osnovnog stanja. Time se dinamika niskoenergijskih pobuda svodi na svojstveni problem odgovarajuće beskonačno dimenzione dinamičke matrice koji se, opet zahvaljujući simetriji, lako rešava metodom modifikovanih grupnih projektora. Kako, međutim, u opštem slučaju grupa simetrije može biti smanjena, predlaže se algoritam za rešavanje svojstvenog problema dinami čke matrice koji efektivno koristi celu grupu. Za monoperiodične sisteme koji su opisani jednom od 13 familija linijskih grupa detaljno se analiziraju transformaciona svojstva tenzora interakcije i Morijina pravila, dok se pojmovi izotropnosti i homogenosti prilagođavaju kvazi-jednodimenzionalnoj geometriji. Izdvaja se prototipni Hamiltonijan koji pored XXZ Hajzenbergovog člana ima i Džalošinski- Morijin vektor usmeren duž ose sistema. Pored tenzora, podrobno se klasifikuju spinske reprezentacije i uređenja prve (najvažnije) familije linijskih grupa; uređenja ostalih familija se dobijaju iz prve, u radu predloženim algoritmom. Konačno, navedeni teorijski koncepti se primenjuju na nedavno sintetisanim 13C nanotubama čiji su nuklearni spinovi putem lutajućih elektrona spregnuti dugo-dometnom Ruderman- Kitel-Kasuja-Josida interakcijom. Dobijena raznolikost helimagnetnih faza koje se kontrolišu naponom, osim toga što ukazuje na univerzalno ponašanje svih nanotuba, kandiduje ih, takođe, za spintroničke uređaje.Subject of this work is symmetry based analysis of systems whose atoms (sites) have non-vanishing magnetic moments (spins), and whose dynamics is governed by Hamiltonians of quadratic forms in spins, i.e. spin-spin interaction is given by the second rank tensor. Commonly, in this field, the translational periodicity of a crystal is used only, while the other symmetries are considered afterwards. Therefore, the main aim of this study is inclusion of the full symmetry of systems in the modeling of the magnetic Hamiltonians first, and then in finding their possible solutions, in particular the quasi-classical ground states and the corresponding low-energy (heli)magnons spectra. To achieve this efficiently, the work is methodologically based on rigorous formalism treating the systems whose geometrical configurations are invariant under the subgroups of the Euclidean group, and whose interactions involve arbitrary levels of neighbours. Starting from the properties of the angular momentum Lie algebra, in quantum-mechanical state space group action is defined, which, due to the invariance principle for Hamiltonian, singles out the axial-vector representation and its constrains on the interaction tensor field. Together with that, the hermiticity of Hamiltonian enables us to generalize the Moria’s rules on all of the allowed components of the interaction. Because of the large dimension of the quantum state space, which is exponentially scaled by the numbers of sites, the solutions of such models are approximate, except in the simplest cases. Thus, restricting the trial set of the variational problem to the separable states, the energy becomes a functional over the site classical vectors, which, in general case, do not have mutually equal lengths. Since, in the mean-field approximation the latter condition is defaulted, in this work, the possibilities that the ground state found in this way is regular, i.e. invariant under a spin group, are considered. For this purpose, it is shown that the classification of the spin groups can be performed using orthogonal three-dimensional real representations (spin representations), by which all the regular arrangements (of mutually equal lengths) are directly determined also. Further on, starting from the assumption that a model is optimized by the regularly arranged classical site spins, and preserving their angular momentum nature, the mapping in the bosonic picture of deviations from the ground state is derived. Thereby, the dynamics of the low-energy excitations is reduced to the eigenproblem of the corresponding infinite-dimensional dynamical matrix, which, owing to symmetry again, is easy to solve by the modified group projectors technique. However, since in general case the symmetry group can be lowered, the algorithm for solving the dynamical matrix eigenproblem, which effectively uses the whole group is proposed. For monoperiodic systems, described by one of the 13 families of the line groups, the transformational properties of interaction tensors are analysed in detail, while the notions of isotropy and homogenity are accommodated to the quasi-one-dimensional geometry. The Hamiltonian prototype, which besides the XXZ Heisenberg term has also the Dzyaloshinskii-Moria vector directed along the system axis, is singled out. In addition to the tensors, spin representations and arrangements of the first (the most important) family line groups are classified thoroughly; the arrangements of the rest of the families are to be obtained from these by the algorithm proposed in the work. Finally, the specified theoretical concepts are applied to the recently synthesized 13C nanotubes, whose nuclear spins are coupled by the long-ranged Ruderman-Kittel- Kasuya-Yosida interaction via itinerant electrons. Besides the obtained diversity of the gate-voltage controlabille helimagnetic phases reveals a universal behaviour of all the nanotubes, it makes them to be the candidates for spintronic devices, too

Distribution of Craniofacial Variables in South Dalmatian and Middle Croatian Populations

The objective of the present work was to determine some relevant craniofacial parameters, particularly in relation to sex, for the study of the distribution of basic head and face types, and to investigate craniofacial and morphological differences between two population samples. The study sample comprised 100 subjects of both sex aged 18 to 30 from South Dalmatia and 200 subjects from Middle Croatia. Eight basic craniofacial variables were measured to obtain head, forehead and face indexes. The data indicate that average values of all variables can be used as standard craniofacial parameters for the examined population groups. All the craniofacial variables are considerably higher in men than in women (p < 0.05). In the South Dalmatian population mesocephalia (48.0%) and leptoprosopia (82.0%) prevail, while in the Middle Croatian population the brachycephalia (62.0%), and euriprosopia (73.5%) are present to a greater degree. The most significant craniofacial and morphological differences between the examined study samples are head width (Eu–Eu), face width (Zy–Zy), and forehead height (Tr–N). They were found to be statistically significant in the examined Middle Croatian population (p < 0.05). The presented measurements are highly relevant to orthodontic diagnostics and therapy

Determination of specific antibodies titre to salmonella enteritidis by elisa technique in several selected flocks of laying hens

In this paper, the antibody titre to Salmonella enteritidis (SE) was examined by the ELISA method in two flocks of laying hens, where during routine bacteriological investigations Salmonellae was never isolated, and in one flock where Colysepticemia was diagnosed and Salmonella isolated accidentally. In the flocks were Salmonellae were not isolated, a titre with a high level of specific antibodies to SE was discovered (15 and 45%), while the flock with accidental findings of SE was poorly positive (5%). These results point to the necessity of introducing serological monitoring to SE so that the infection of salmonella may be discovered early and the prevalence in the flock determined, and also for the purpose of applying adequate measures that could reduce the possibility of secretion of SE through eggs

Enhanced human papillomavirus type 8 oncogene expression levels are crucial for skin tumorigenesis in transgenic mice

AbstractHuman papillomavirus 8 (HPV8) is involved in skin cancer development in epidermodysplasia verruciformis patients. Transgenic mice expressing HPV8 early genes (HPV8-CER) developed papillomas, dysplasias and squamous cell carcinomas. UVA/B-irradiation and mechanical wounding of HPV8-CER mouse skin led to prompt papilloma induction in about 3weeks. The aim of this study was to analyze the kinetics and level of transgene expression in response to skin irritations. Transgene expression was already enhanced 1 to 2days after UVA/B-irradiation or tape-stripping and maintained during papilloma development. The enhanced transgene expression could be assigned to UVB and not to UVA. Papilloma development was thus always paralleled by an increased transgene expression irrespective of the type of skin irritation. A knock-down of E6 mRNA by tattooing HPV8-E6-specific siRNA led to a delay and a lower incidence of papilloma development. This indicates that the early increase of viral oncogene expression is crucial for induction of papillomatosis

wild birds in Serbia during 2012: first isolation and characterisation of WNV strains from Serbia

Monitoring West Nile virus (WNV) infection i