Production of a sterile species: Quantum kinetics

Production of a sterile species is studied within an effective model of active-sterile neutrino mixing in a medium in thermal equilibrium. The quantum kinetic equations for the distribution functions and coherences are obtained from two independent methods: the effective action and the quantum master equation. The decoherence time scale for active-sterile oscillations is tau(dec)=2/Gamma(aa), but the evolution of the distribution functions is determined by the two different time scales associated with the damping rates of the quasiparticle modes in the medium: Gamma(1)=Gamma(aa)cos^2theta(m); Gamma(2)=Gamma(aa)sin^2theta(m) where Gamma(aa) is the interaction rate of the active species in the absence of mixing and theta(m) the mixing angle in the medium. These two time scales are widely different away from Mikheyev-Smirnov-Wolfenstein resonances and preclude the kinetic description of active-sterile production in terms of a simple rate equation. We give the complete set of quantum kinetic equations for the active and sterile populations and coherences and discuss in detail the various approximations. A generalization of the active-sterile transition probability in a medium is provided via the quantum master equation. We derive explicitly the usual quantum kinetic equations in terms of the"polarization vector" and show their equivalence to those obtained from the quantum master equation and effective action

Characterization of 13 multi-drug resistant Salmonella serovars from different broiler chickens associated with those of human isolates

<p>Abstract</p> <p>Background</p> <p><it>Salmonella </it>are frequently isolated from chickens and their products. Prevalent serogroups and serovars of <it>Salmonella </it>as well as their genotypes and antibiograms were determined for cloacal samples from 1595 chickens. To understand the possible serovar and H antigens for transmission between chicken and human, serovars and their H antigens of 164 chicken and 5314 human isolates were compared.</p> <p>Results</p> <p>Prevalence of <it>Salmonella </it>differed among chicken lines and ages. Chicken and human isolates belonged mainly to serogroup B, C1, C2-C3, D, and E. 13 serovars and 66 serovars were identified for chicken and human isolates respectively. The common serovars for chicken and human isolates were <it>S</it>. Typhimurium, <it>S</it>. Enteritidis, <it>S</it>. Albany, <it>S</it>. Derby, and <it>S</it>. Anatum and shared common H1 antigens "g complex; i; e,h; and z4,z24" and H2 antigens "1 complex and -". In human isolates, H1 antigen "i" and H2 antigen "-" were common in all serogroups. In chicken, antimicrobial susceptibility differed among serogroups, serovars and three counties. All isolates were susceptible to cefazolin and ceftriaxone, but highly resistant to ampicillin, chloramphenicol, flumequine, streptomycin, sulfamethoxazole-trimethoprim, and tetracycline. Except those isolates of serogroup C1 of Chick group and serogroup G, all isolates were multi-drug resistance. Only <it>S</it>. Kubacha, <it>S</it>. Typhimurium, <it>S</it>. Grampian, and <it>S</it>. Mons were resistant to ciprofloxacin and/or enrofloxacin.</p> <p>Conclusion</p> <p>In chicken, prevalent serogroups and serovars were associated with chicken ages, lines and regions; and flouroquinolone-resistant and MDR isolates emerged. H1 antigens "g complex and i" and H2 antigens "1 complex and -" might be important for transmission of <it>Salmonella </it>between chicken and human.</p

Open Gromov-Witten Invariants of Toric Calabi-Yau 3-Folds

We present a proof of the mirror conjecture of Aganagic-Vafa [arXiv:hep-th/0012041] and Aganagic-Klemm-Vafa [arXiv:hep-th/0105045] on disk enumeration in toric Calabi-Yau 3-folds for all smooth semi-projective toric Calabi-Yau 3-folds. We consider both inner and outer branes, at arbitrary framing. In particular, we recover previous results on the conjecture for (i) an inner brane at zero framing in the total space of the canonical line bundle of the projective plane (Graber-Zaslow [arXiv:hep-th/0109075]), (ii) an outer brane at arbitrary framing in the resolved conifold (Zhou [arXiv:1001.0447]), and (iii) an outer brane at zero framing in the total space of the canonical line bundle of the projective plane (Brini [arXiv:1102.0281, Section 5.3]).Comment: 39 pages, 11 figure

The combined role of MRI prostate and prostate health index in improving detection of significant prostate cancer in a screening population of Chinese men

Using prostate-specific antigen (PSA) for prostate cancer (PCa) screening led to overinvestigation and overdiagnosis of indolent PCa. We aimed to investigate the value of prostate health index (PHI) and magnetic resonance imaging (MRI) prostate in an Asian PCa screening program. Men aged 50-75 years were prospectively recruited from a community-based PSA screening program. Men with PSA 4.0-10.0 ng ml -1 had PHI result analyzed. MRI prostate was offered to men with PSA 4.0-50.0 ng ml -1. A systematic prostate biopsy was offered to men with PSA 4.0-9.9 ng ml -1 and PHI ≥35, or PSA 10.0-50.0 ng ml -1. Additional targeted prostate biopsy was offered if they had PI-RADS score ≥3. Clinically significant PCa (csPCa) was defined as the International Society of Urological Pathology (ISUP) grade group (GG) ≥2 or ISUP GG 1 with involvement of ≥30% of total systematic cores. In total, 12.8% (196/1536) men had PSA ≥4.0 ng ml -1. Among 194 men with PSA 4.0-50.0 ng ml -1, 187 (96.4%) received MRI prostate. Among them, 28.3% (53/187) had PI-RADS ≥3 lesions. Moreover, 7.0% (107/1536) men were indicated for biopsy and 94.4% (101/107) men received biopsy. Among the men received biopsy, PCa, ISUP GG ≥2 PCa, and csPCa was diagnosed in 42 (41.6%), 24 (23.8%), and 34 (33.7%) men, respectively. Compared with PSA/PHI pathway in men with PSA 4.0-50.0 ng ml -1, additional MRI increased diagnoses of PCa, ISUP GG ≥2 PCa, and csPCa by 21.2% (from 33 to 40), 22.2% (from 18 to 22), and 18.5% (from 27 to 32), respectively. The benefit of additional MRI was only observed in PSA 4.0-10.0 ng ml -1, and the number of MRI needed to diagnose one additional ISUP GG ≥2 PCa was 20 in PHI ≥35 and 94 in PHI &lt;35. Among them, 45.4% (89/196) men with PSA ≥4.0 ng ml -1 avoided unnecessary biopsy with the use of PHI and MRI. A screening algorithm with PSA, PHI, and MRI could effectively diagnose csPCa while reducing unnecessary biopsies. The benefit of MRI prostate was mainly observed in PSA 4.0-9.9 ng ml -1 and PHI ≥35 group. PHI was an important risk stratification step for PCa screening.</p

Analysis technique for exceptional points in open quantum systems and QPT analogy for the appearance of irreversibility

We propose an analysis technique for the exceptional points (EPs) occurring in the discrete spectrum of open quantum systems (OQS), using a semi-infinite chain coupled to an endpoint impurity as a prototype. We outline our method to locate the EPs in OQS, further obtaining an eigenvalue expansion in the vicinity of the EPs that gives rise to characteristic exponents. We also report the precise number of EPs occurring in an OQS with a continuum described by a quadratic dispersion curve. In particular, the number of EPs occurring in a bare discrete Hamiltonian of dimension $n_\textrm{D}$ is given by $n_\textrm{D} (n_\textrm{D} - 1)$; if this discrete Hamiltonian is then coupled to continuum (or continua) to form an OQS, the interaction with the continuum generally produces an enlarged discrete solution space that includes a greater number of EPs, specifically $2^{n_\textrm{C}} (n_\textrm{C} + n_\textrm{D}) [2^{n_\textrm{C}} (n_\textrm{C} + n_\textrm{D}) - 1]$, in which $n_\textrm{C}$ is the number of (non-degenerate) continua to which the discrete sector is attached. Finally, we offer a heuristic quantum phase transition analogy for the emergence of the resonance (giving rise to irreversibility via exponential decay) in which the decay width plays the role of the order parameter; the associated critical exponent is then determined by the above eigenvalue expansion.Comment: 16 pages, 7 figure

Computational Physics on Graphics Processing Units

The use of graphics processing units for scientific computations is an emerging strategy that can significantly speed up various different algorithms. In this review, we discuss advances made in the field of computational physics, focusing on classical molecular dynamics, and on quantum simulations for electronic structure calculations using the density functional theory, wave function techniques, and quantum field theory.Comment: Proceedings of the 11th International Conference, PARA 2012, Helsinki, Finland, June 10-13, 201

Motivation and Knowledge Sharing through Social Media within Danish Organizations

Part 3: Creating Value through ApplicationsInternational audienceBased on an empirical quantitative study, this article investigates employee motivation in Danish companies and aims at determining which factors affect employees’ knowledge sharing through social media in a working environment. Our findings pinpoint towards the potential social media have for enhancing internal communication, knowledge sharing and collaboration in organizations, but the adoption is low, at this point, due to mainly organizational and individual factors. Technological factors do not seem to affect employees’ motivation for knowledge sharing as much as previous research has found, but it is the influence from the combination of individual and organizational factors, which affect the adoption of the platforms. A key finding in the study is that knowledge sharing is not a ‘social dilemma’ as previous studies have found. The study shows a positive development in employees’ willingness to share knowledge, because knowledge sharing is considered more beneficial than to hoard it

Knowledge Sharing Idiosyncrasies of University Students in Ghana

Part 6: Decision Making and Knowledge ManagementInternational audienceThis study explored the factors affecting knowledge sharing behaviour of students in a higher institution of learning. Using a model derived from the Social Cognitive Theory and the Theory of Reason Action, six hypotheses were tested from a cross-sectional data collected from 371 undergraduate students on a 4-year degree programme in the University of Ghana. Five out of the six hypotheses were supported. The results showed that the knowledge sharing behaviour (KSB) of the students was significantly related to five of the human and environmental factors (F=639.9, df=5, 290, p<0.05) with a co-efficient of variation of R2=0.917 (91.7%). The knowledge sharing behavior of the students was, however, not significantly dependent on their personal characteristics. The study makes a case for increased attention in understanding the human and environmental factors of knowledge sharing since knowledge sharing is largely a people activity shaped by culture

Patients' Understanding of How Genotype Variation Affects Benefits of Tamoxifen Therapy for Breast Cancer

CYP2D6 is a critical enzyme in the metabolism of tamoxifen and potentially a key determinant in breast cancer outcomes. Our study examined patients' beliefs about how CYP2D6 genotype would affect their prognoses