On Essential and Inessential Polygons in Embedded Graphs

AbstractIn this article, we present a number of results of the following type: A given subgraph of an embedded graph either is embedded in a disc or it has a face chain containing a non-contractible closed path. Our main application is to prove that any two faces of a 4-representative embedding are simultaneously contained in a disc bounded by a polygon. This result is used to prove the existence of ⌊(r−1)/8⌋ pairwise disjoint, pairwise homotopic non-contractible separating polygons in an r -representative orientable embedding. Our proof of this latter result is simple and mechanical

Spin-1/2 J1-J2 model on the body-centered cubic lattice

Using exact diagonalization (ED) and linear spin wave theory (LSWT) we study the influence of frustration and quantum fluctuations on the magnetic ordering in the ground state of the spin-1/2 J1-J2 Heisenberg antiferromagnet (J1-J2 model) on the body-centered cubic (bcc) lattice. Contrary to the J1-J2 model on the square lattice, we find for the bcc lattice that frustration and quantum fluctuations do not lead to a quantum disordered phase for strong frustration. The results of both approaches (ED, LSWT) suggest a first order transition at J2/J1 $\approx$ 0.7 from the two-sublattice Neel phase at low J2 to a collinear phase at large J2.Comment: 6.1 pages 7 figure

Multi-triangulations as complexes of star polygons

Maximal $(k+1)$-crossing-free graphs on a planar point set in convex position, that is, $k$-triangulations, have received attention in recent literature, with motivation coming from several interpretations of them. We introduce a new way of looking at $k$-triangulations, namely as complexes of star polygons. With this tool we give new, direct, proofs of the fundamental properties of $k$-triangulations, as well as some new results. This interpretation also opens-up new avenues of research, that we briefly explore in the last section.Comment: 40 pages, 24 figures; added references, update Section

Classical approach in quantum physics

The application of a classical approach to various quantum problems - the secular perturbation approach to quantization of a hydrogen atom in external fields and a helium atom, the adiabatic switching method for calculation of a semiclassical spectrum of hydrogen atom in crossed electric and magnetic fields, a spontaneous decay of excited states of a hydrogen atom, Gutzwiller's approach to Stark problem, long-lived excited states of a helium atom recently discovered with the help of Poincar$\acute{\mathrm{e}}$ section, inelastic transitions in slow and fast electron-atom and ion-atom collisions - is reviewed. Further, a classical representation in quantum theory is discussed. In this representation the quantum states are treating as an ensemble of classical states. This approach opens the way to an accurate description of the initial and final states in classical trajectory Monte Carlo (CTMC) method and a purely classical explanation of tunneling phenomenon. The general aspects of the structure of the semiclassical series such as renormgroup symmetry, criterion of accuracy and so on are reviewed as well. In conclusion, the relation between quantum theory, classical physics and measurement is discussed.Comment: This review paper was rejected from J.Phys.A with referee's comment "The author has made many worthwhile contributions to semiclassical physics, but this article does not meet the standard for a topical review"

Epidemiological situation of bovine brucellosis in the State of Rio Grande do Sul, Brazil

Realizou-se um estudo para caracterizar a situação epidemiológica da brucelose bovina. O Estado foi dividido em sete regiões. Em cada região foram amostradas aleatoriamente cerca de 300 propriedades, e dentro dessas foi escolhido de forma aleatória um número pré-estabelecido de animais, dos quais foi obtida uma amostra de sangue. No total foram amostrados 16.072 animais, provenientes de 1.957 propriedades. Em cada propriedade amostrada foi aplicado um questionário epidemiológico para verificar o tipo de exploração e as práticas zootécnicas e sanitárias que poderiam estar associadas ao risco de infecção pela doença. O protocolo de testes utilizado foi o da triagem com o teste do antígeno acidificado tamponado e o reteste dos positivos com o teste do 2-mercaptoetanol. O rebanho foi considerado positivo se pelo menos um animal foi reagente às duas provas sorológicas. Para o Estado, as prevalências de focos e de animais infectados foram, respectivamente, 2,1% [1,5-2,6%] e 1,0% [0,60-1,4%]. Para os circuitos, a prevalência de focos e a de animais foram, respectivamente: circuito 1, 3,1% [1,4-5,7%] e 0,95% [0,0-2,0%]; circuito 2, 7,7% [4,9-11,3%] e 1,0% [0,40-1,7%]; circuito 3, 5,7% [3,4-8,8%] e 2,1% [0,41-3,8%]; circuito 4, 0,66% [0,08-2,4%] e 0,66% [0,0-1,8%]; circuito 5, 0,66% [0,08-2,4%] e 0,05% [0,0-0,13%]; circuito 6, 0,0% [0,0-1,3%] e 0,0% [0,0-0,25%]; circuito 7, 5,4% [2,5-10,1%] e 2,9% [0,49-5,3%]. Os fatores de risco (odds ratio, OR) associados à condição de foco foram: exploração de corte (OR= 4,27 [1,82-10,01]) e histórico de aborto (OR=3,27,1,71-6,25]). ____________________________________________________________________________________________________________ ABSTRACTA study to characterize the epidemiological status of bovine brucellosis was carried out in the State of Rio Grande do Sul. The State was divided in seven regions. Three hundred herds were randomly sampled in each region and a pre-established number of animals were sampled in each of these herds. A total of 16,072 serum samples from 1,957 herds, were collected. In each herd, it was applied an epidemiological questionnaire focused on herd traits as well as husbandry and sanitary practices that could be associated with the risk of infection. The serum samples were screened for antibodies against Brucella spp. by the Rose-Bengal Test and all positive sera were re-tested by the 2-mercaptoethanol test. The herd was considered positive if at least one animal was positive on both tests. The prevalences of infected herds and animals in the State were, respectively 2.1% [1.5-2.6%] and 1.0% [0.60-1.4%]. In the regions, the prevalences of infected herds and animals were, respectively: region 1, 3.1% [1.4-5.7%] and 0.95% [0.0-2.0%]; region 2, 7.7% [4.9-11.3%] and 1.0% [0.40-1.7%]; region 3, 5.7% [3.4-8.8%] and 2.1% [0.41-3.8%]; region 4, 0.66% [0.08-2.4%] and 0.66% [0.0-1.8%]; region 5, 0.66% [0.08-2.4%] and 0.05% [0.0-0.13%]; region 6, 0.0% [0.0-1.3%] and 0.0% [0.0-0.25%]; and region 7, 5.4% [2.5-10.1%] and 2.9% [0.49-5.3%]. The risk factors (odds ratio, OR) associated with the presence of infection were: beef herd (OR= 4.27 [1.82-10.01]) and recent history of abortion (OR= 3.27-1.71-6.25])

Computer-aided design of nano-filter construction using DNA self-assembly

Computer-aided design plays a fundamental role in both top-down and bottom-up nano-system fabrication. This paper presents a bottom-up nano-filter patterning process based on DNA self-assembly. In this study we designed a new method to construct fully designed nano-filters with the pores between 5 nm and 9 nm in diameter. Our calculations illustrated that by constructing such a nano-filter we would be able to separate many molecules

Anisotropic flow of charged hadrons, pions and (anti-)protons measured at high transverse momentum in Pb-Pb collisions at sNN=2.76\sqrt{s_{\rm NN}}=2.76 TeV

The elliptic, $v_2$, triangular, $v_3$, and quadrangular, $v_4$, azimuthal anisotropic flow coefficients are measured for unidentified charged particles, pions and (anti-)protons in Pb-Pb collisions at $\sqrt{s_{\rm NN}} = 2.76$ TeV with the ALICE detector at the Large Hadron Collider. Results obtained with the event plane and four-particle cumulant methods are reported for the pseudo-rapidity range $|\eta|<0.8$ at different collision centralities and as a function of transverse momentum, $p_{\rm T}$, out to $p_{\rm T}=20$ GeV/$c$. The observed non-zero elliptic and triangular flow depends only weakly on transverse momentum for $p_{\rm T}>8$ GeV/$c$. The small $p_{\rm T}$ dependence of the difference between elliptic flow results obtained from the event plane and four-particle cumulant methods suggests a common origin of flow fluctuations up to $p_{\rm T}=8$ GeV/$c$. The magnitude of the (anti-)proton elliptic and triangular flow is larger than that of pions out to at least $p_{\rm T}=8$ GeV/$c$ indicating that the particle type dependence persists out to high $p_{\rm T}$.Comment: 16 pages, 5 captioned figures, authors from page 11, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/186

Centrality dependence of charged particle production at large transverse momentum in Pb-Pb collisions at sNN=2.76\sqrt{s_{\rm{NN}}} = 2.76 TeV

The inclusive transverse momentum ($p_{\rm T}$) distributions of primary charged particles are measured in the pseudo-rapidity range $|\eta|<0.8$ as a function of event centrality in Pb-Pb collisions at $\sqrt{s_{\rm{NN}}}=2.76$ TeV with ALICE at the LHC. The data are presented in the $p_{\rm T}$ range $0.15<p_{\rm T}<50$ GeV/$c$ for nine centrality intervals from 70-80% to 0-5%. The Pb-Pb spectra are presented in terms of the nuclear modification factor $R_{\rm{AA}}$ using a pp reference spectrum measured at the same collision energy. We observe that the suppression of high-$p_{\rm T}$ particles strongly depends on event centrality. In central collisions (0-5%) the yield is most suppressed with $R_{\rm{AA}}\approx0.13$ at $p_{\rm T}=6$-7 GeV/$c$. Above $p_{\rm T}=7$ GeV/$c$, there is a significant rise in the nuclear modification factor, which reaches $R_{\rm{AA}} \approx0.4$ for $p_{\rm T}>30$ GeV/$c$. In peripheral collisions (70-80%), the suppression is weaker with $R_{\rm{AA}} \approx 0.7$ almost independently of $p_{\rm T}$. The measured nuclear modification factors are compared to other measurements and model calculations.Comment: 17 pages, 4 captioned figures, 2 tables, authors from page 12, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/284

Measurement of the polarisation of W bosons produced with large transverse momentum in pp collisions at sqrt(s) = 7 TeV with the ATLAS experiment

This paper describes an analysis of the angular distribution of W->enu and W->munu decays, using data from pp collisions at sqrt(s) = 7 TeV recorded with the ATLAS detector at the LHC in 2010, corresponding to an integrated luminosity of about 35 pb^-1. Using the decay lepton transverse momentum and the missing transverse energy, the W decay angular distribution projected onto the transverse plane is obtained and analysed in terms of helicity fractions f0, fL and fR over two ranges of W transverse momentum (ptw): 35 < ptw < 50 GeV and ptw > 50 GeV. Good agreement is found with theoretical predictions. For ptw > 50 GeV, the values of f0 and fL-fR, averaged over charge and lepton flavour, are measured to be : f0 = 0.127 +/- 0.030 +/- 0.108 and fL-fR = 0.252 +/- 0.017 +/- 0.030, where the first uncertainties are statistical, and the second include all systematic effects.Comment: 19 pages plus author list (34 pages total), 9 figures, 11 tables, revised author list, matches European Journal of Physics C versio