Valley symmetry breaking in bilayer graphene: a test to the minimal model

Physical properties reflecting valley asymmetry of Landau levels in a biased bilayer graphene under magnetic field are discussed. Within the $4-$band continuum model with Hartree-corrected self-consistent gap and finite damping factor we predict the appearance of anomalous steps in quantized Hall conductivity due to the degeneracy lifting of Landau levels. Moreover, the valley symmetry breaking effect appears as a non-semiclassical de Haas-van Alphen effect where the reduction of the oscillation period to half cannot be accounted for through quasi-classical quantization of the orbits in reciprocal space, still valley degenerate.Comment: 4 pages, 3 figure

Potrebe u ishrani mlađi štuke (esox lucius) gajene u recirkulacionom sistemu

Zahvaljujući napretku tehnologije, danas je moguće intenzivno gajenje juvenilne štuke u recirkulacionom sistemu korišćenjem formulisane komercijalne hrane (Wolnicki i Górny 1997). Komercijalna hrana koja se trenutno koristi za ishranu štuke je formulisana za druge vrste kao što su pastrmka, som i jesetra. Ova hrana se veoma razlikuje po sastavu proteina i sadržaju energije, što može da utiče na parametre proizvodnje. Smanjivanje odnosa svrarljivosti proteina/energetska efikasnost (DP/DE) u smešama može dovesti do većeg zadržavanja proteina, međutim može imati efekte na zdravlje riba i kvalitet proizvoda. Prvi cilj ove studije je bio da se istraži efekat komercijalnih smeša sa različitom koncentracijom proteina i lipida na juvenilne štuke manje od 20g (eksperiment I) i preko 70g (eksperiment II). Današnji trendovi u proizvodnji hrane za ribe su usmereni u pravcu zamene ribljeg brašna alternativnim izvorima proteina kao što su biljke, suvozemne životinje i nus-proizvodi. Ovi trendovi su dirigovani kako ekonomskim tako i etičkim pitanjima (Brinker and Reiter 2011). Drugi cilj ovog rada je bio da se istraži delimična zamena ribljeg brašna u smešama. U trećem eksperimentu, ispitivana je delimična zamena ribljeg brašna sa pšeničnim glutenom i živinskim brašnom

Multiple Benefits of Plasmid-Mediated Quinolone Resistance Determinants in Klebsiella pneumoniae ST11 High-Risk Clone and Recently Emerging ST307 Clone

International high-risk clones of Klebsiella pneumoniae are among the most common nosocomial pathogens. Increased diversity of plasmid-encoded antimicrobial resistance genes facilitates spread of these clones causing significant therapeutic difficulties. The purpose of our study was to investigate fluoroquinolone resistance in extended-spectrum beta-lactamase (ESBL)-producing strains, including four K. pneumoniae and a single K. oxytoca, isolated from blood cultures in Hungary. Whole-genome sequencing and molecular typing including multilocus sequence typing (MLST) and pulsed-field gel electrophoresis (PFGE) were performed in selected strains. Gene expression of plasmid-mediated quinolone resistance determinants (PMQR) was investigated by quantitative-PCR. MLST revealed that three K. pneumoniae strains belonged to ST11 and one to ST307 whereas K. oxytoca belonged to ST52. The isolates harbored different β-lactamase genes, however, all K. pneumoniae uniformly carried blaCTX-M-15. The K. pneumoniae isolates exhibited resistance to fluoroquinolones and carried various PMQR genes namely, two ST11 strains harbored qnrB4, the ST307 strain harbored qnrB1 and all K. pneumoniae harbored oqxAB efflux pump. Levofloxacin and moxifloxacin MIC values of K. pneumoniae ST11 and ST307 clones correlated with qnr and oqxAB expression levels. The qnrA1 carrying K. oxytoca ST52 exhibited reduced susceptibility to fluoroquinolones. The maintained expression of qnr genes in parallel with chromosomal mutations indicate an additional protective role of Qnr proteins that can support dissemination of high-risk clones. During development of high-level fluoroquinolone resistance, high-risk clones retain fitness thus, enabling them for dissemination in hospital environment. Based on our knowledge this is the first report of ST307 clone in Hungary, that is emerging as a potential high-risk clone worldwide. High-level fluoroquinolone resistance in parallel with upregulated PMQR gene expression are linked to high-risk K. pneumoniae clones

Poreklo i genetička struktura nekoliko mađarskih divljih i domestifikovanih populacija potočne pastrmke na osnovu PCR-RFLP i mikrosatelitskih markera

U Evropi je, na osnovu studija mitohondrijalne DNK, identifikovano pet evolutivnih linija potočne pastrmke (Salmo trutta m. fario L. 1758): Atlanska, Dunavska, Mediteranska, Jadranska i Mramorna. Mađarske linije bi teorijski trebalo da pripadaju Dunavskoj liniji na osnovu hidrogeografije zemlje, ipak, ovo nije potvrđeno genetičkim studijama. Korišćeni su molekularni markeri da bi se ispitalo genetička pozadina populacije potočne pastrmke u Mađarskoj. Istraživanja su uključila jedini matični nasad potočne pastrmke u Mađarskoj, kao i po jedna populacije u planinskim vencima Bükk, Aggtelek, Börzsöny i Visegrádi, po jedna populacija u svakom. Genetička analiza je do sada sprovedena na 533 individue, isečak peraja je uzorkovan sa svake ribe i PCR-RFLP (kontrolni region mitohondrijalne DNK, laktat dehidrogenaza i somatolaktin geni), kao i analiza mikrosatelitnih markeri (BFRO002, OMM1064, Ssa408uos, SsoSL417, SsoSL438) su bili korišćeni da bi se razlikovale Dunavska i Atlanska linija potočne pastrmke. Na osnovu genetičke analize mitohondrijalne DNK divljih populacija, udeo Dunavskog haplotipa je nizak (< 10 %), sa izuzetkom potoka Apátkúti u planinama Visegrádi, gde je nađena relativno visok udeo Dunavskog haplotipa (34%). 401 analizirani primerak matičnog jata farme je skoro u potpunosti Atlanski haplotip, što ukazuje na efekat osnivača. Iako su kasnije prikupljeni primerci iz obližnjeg potoka i pridodati matičnom jatu, njihov broj je bio ograničen jer su uglavnom svi bili mužjaci. Budući da je jedino matično jato u Mađarskoj, ribe sa ove farme se koriste za poribljavanje od strane ribolovaca, što može dovesti do značajnog uticaja na prirodne populacije. Na osnovu analize nuklearnih markera sve populacije su veoma heterogene. Veliki udeo (60-80%) Atlanskih alela primećen za ove markere na svim lokacijama gde je obavljano uzorkovanje ukazuje na efekat intenzivnog poribljavanja mađarskih salmonidnih regiona. Analize mikrosatelitskih markera su ukazale na visoku heterozigotnost i Hardy-Weinberg-ovu ravnotežu svih populacija

Gyeptelepítés elmélete és gyakorlata az ökológiai szemléletű gazdálkodásban

Az utóbbi években egyre nagyobb az igény mind hazánkban, mind Európában a szántóföldi művelés alól kivett területek alternatív, fenntartható hasznosítására, melyre jó lehetőséget biztosít az ökológiai szemléletű gyepgazdálkodás. A gyepesítéssel szemben támasztott legfontosabb elvárás egy főképp füvek dominálta évelő gyep létrejötte, amely visszaszorítja a nemkívánatos gyomfajokat. Ökológiai célú gyeptelepítés esetén rendkívül fontos a megfelelő szaporítóanyagok, a megfelelő fűfajok kiválasztása és a természetkímélő technológia alkalmazása. A telepítendő fajokat a terület ökológiai jellemzőinek (talajtípus, vízgazdálkodás, hőmérséklet és csapadék viszonyok) figyelembe vételével és a későbbi hasznosítás (legeltetés, kaszálás) szempontjait szem előtt tartva kell kiválasztani. A telepítés időpontját és technológiáját szintén össze kell hangolni a termőhelyi adottságokkal és a későbbi hasznosítással. Legújabb kiadványunk olyan tudományos igényességgel kidolgozott, de a mindennapi gazdálkodásban alkalmazható szakanyag, amely felhívja a figyelmet az ökológiai szempontú gyeptelepítés legfontosabb szempontjaira, a gyeptelepítéshez használt magkeverékkel szemben támasztott kívánalmakra, a telepítés gyakorlati kivitelezésére, valamint várható gép- és költségigényére. A kiadvány a Debreceni Egyetem Ökológiai Tanszéke közreműködésével, Dr. Török Péter szerkesztésében valósult meg. A projekt a Magyar Nemzeti Vidéki Hálózat Elnökségének értékelése és javaslata alapján, az Európai Mezőgazdasági és Vidékfejlesztési Alap társfinanszírozásában, a Nemzeti Vidékfejlesztési Program Irányító Hatóságának jóváhagyásával válhatott valóra

Quenching through Dirac and semi-Dirac points in optical Lattices: Kibble-Zurek scaling for anisotropic Quantum-Critical systems

We propose that Kibble-Zurek scaling can be studied in optical lattices by creating geometries that support, Dirac, Semi-Dirac and Quadratic Band Crossings. On a Honeycomb lattice with fermions, as a staggered on-site potential is varied through zero, the system crosses the gapless Dirac points, and we show that the density of defects created scales as $1/\tau$, where $\tau$ is the inverse rate of change of the potential, in agreement with the Kibble-Zurek relation. We generalize the result for a passage through a semi-Dirac point in $d$ dimensions, in which spectrum is linear in $m$ parallel directions and quadratic in rest of the perpendicular $(d-m)$ directions. We find that the defect density is given by $1 /{\tau^{m\nu_{||}z_{||}+(d-m)\nu_{\perp}z_{\perp}}}$ where $\nu_{||}, z_{||}$ and $\nu_{\perp},z_{\perp}$ are the dynamical exponents and the correlation length exponents along the parallel and perpendicular directions, respectively. The scaling relations are also generalized to the case of non-linear quenching

Non-Hermitian Kibble-Zurek mechanism with tunable complexity in single-photon interferometry

Non-Hermitian descriptions of quantum matter have seen impressive progress recently, with major advances in understanding central aspects such as their topological properties or the physics of exceptional points, the non-Hermitian counterpart of critical points. Here, we use single-photon interferometry to reconstruct the non-Hermitian Kibble-Zurek mechanism and its distinct scaling behavior for exceptional points, by simulating the defect production upon performing slow parameter ramps. Importantly, we are able to realise also higher-order exceptional points, providing experimental access to their theoretically predicted characteristic Kibble-Zurek scaling behaviour. Our work represents a crucial step in increasing the experimental complexity of non-Hermitian quantum time-evolution. It thus also furthers the quest to move the frontier from purely single-particle physics towards increasingly complex settings in the many-body realm.Comment: 8 pages, 6 figure

Disorder Promotes Ferromagnetism: Rounding of the Quantum Phase Transition in Sr₁₋ₓCaₓRuO₃

The subtle interplay of randomness and quantum fluctuations at low temperatures gives rise to a plethora of unconventional phenomena in systems ranging from quantum magnets and correlated electron materials to ultracold atomic gases. Particularly strong disorder effects have been predicted to occur at zero-temperature quantum phase transitions. Here, we demonstrate that the composition-driven ferromagnetic-to-paramagnetic quantum phase transition in Sr1-xCaxRuO3 is completely destroyed by the disorder introduced via the different ionic radii of the randomly distributed Sr and Ca ions. Using a magneto-optical technique, we map the magnetic phase diagram in the composition-temperature space. We find that the ferromagnetic phase is significantly extended by the disorder and develops a pronounced tail over a broad range of the composition x. These findings are explained by a microscopic model of smeared quantum phase transitions in itinerant magnets. Moreover, our theoretical study implies that correlated disorder is even more powerful in promoting ferromagnetism than random disorder