5,226 research outputs found

    Global disease monitoring and forecasting with Wikipedia

    Full text link
    Infectious disease is a leading threat to public health, economic stability, and other key social structures. Efforts to mitigate these impacts depend on accurate and timely monitoring to measure the risk and progress of disease. Traditional, biologically-focused monitoring techniques are accurate but costly and slow; in response, new techniques based on social internet data such as social media and search queries are emerging. These efforts are promising, but important challenges in the areas of scientific peer review, breadth of diseases and countries, and forecasting hamper their operational usefulness. We examine a freely available, open data source for this use: access logs from the online encyclopedia Wikipedia. Using linear models, language as a proxy for location, and a systematic yet simple article selection procedure, we tested 14 location-disease combinations and demonstrate that these data feasibly support an approach that overcomes these challenges. Specifically, our proof-of-concept yields models with r2r^2 up to 0.92, forecasting value up to the 28 days tested, and several pairs of models similar enough to suggest that transferring models from one location to another without re-training is feasible. Based on these preliminary results, we close with a research agenda designed to overcome these challenges and produce a disease monitoring and forecasting system that is significantly more effective, robust, and globally comprehensive than the current state of the art.Comment: 27 pages; 4 figures; 4 tables. Version 2: Cite McIver & Brownstein and adjust novelty claims accordingly; revise title; various revisions for clarit

    A method for determining CP violating phase γ\gamma

    Full text link
    A new way of determining the phases of weak amplitudes in charged BB decays based on SU(3) symmetry is proposed. The CP violating phase γ\gamma can now be determined without the previous difficulty associated with electroweak penguins.Comment: 9 pages plus one figure, Revte

    Electroweak Model Independent Tests for SU(3) Symmetry in Hadronic B Decays

    Get PDF
    We study effects of new physics beyond the Standard Model on SU(3) symmetry in charmless hadronic two body B decays. It is found that several equalities for some of the decay amplitudes, such as A(Bd(Bu)π+π,π+K(πKˉ0))=A(BsK+π,KK+(K0Kˉ0))A(B_d (B_u) \to \pi^+\pi^-,\pi^+ K^- (\pi^- \bar K^0)) =A(B_s \to K^+ \pi^-, K^- K^+ (K^0 \bar K^0)), A(Bdπ+ρ,πρ+,Kρ+,π+K)=A(BsK+ρ,πK+,KK+,K+K)A(B_d \to \pi^+\rho^-, \pi^- \rho^+, K^-\rho^+, \pi^+ K^{*-}) = A(B_s \to K^+ \rho^-, \pi^- K^{*+}, K^- K^{*+}, K^+ K^{*-}), A(Bd(Bu)ρ+ρ,ρ+K(ρKˉ0))=A(BsK+ρ,KK+(K0Kˉ0))A(B_d (B_u) \to \rho^+\rho^-, \rho^+ K^{*-}(\rho^- \bar K^{*0})) =A(B_s \to K^{*+} \rho^-, K^{*-} K^{*+} (K^{*0} \bar K^{*0})), predicted by SU(3) symmetry in the SM are not affected by new physics. These relations provide important electroweak model independent tests for SU(3) symmetry in B decays.Comment: 4 pages, revte

    CP Violation in a Multi-Higgs Doublet Model

    Get PDF
    We study CP violation in a multi-Higgs doublet model based on a S3×Z3S_3 \times Z_3 horizontal symmetry. We consider two mechanisms for CP violation in this model: a) CP violation due to complex Yukawa couplings; and b) CP violation due to scalar-pseudoscalar mixings. We find that the predictions for ϵ/ϵ\epsilon'/\epsilon, CP violation in B decays and the electric dipole moments of neutron and electron are different between these two mechanisms. These predictions are also dramatically different from the minimal Standard Model predictions.Comment: 17 pages + one figure, Revtex. Talk presented by Deshpande at the Conference WHEPP-3, December 199

    The CP violating phase γ\gamma from global fit of rare charmless hadronic B decays

    Full text link
    We study constraints on the CP violating phase γ\gamma in the Kobayashi-Maskawa model using available experimental data. We first follow the conventional method to up date the constraint on γ\gamma by performing a χ2\chi^2 analysis using data from ϵK|\epsilon_K|, ΔmBd,s\Delta m_{B_{d,s}} and Vub/Vcb|V_{ub}/V_{cb}|. We also include the recent information on sin2β\sin2\beta in the analysis. We obtain the best fit for γ\gamma to be 6666^\circ and the 95% C.L. allowed range to be 428742^\circ \sim 87^\circ. We then develop a method to carry out a χ2\chi^2 analysis based on SU(3) symmetry using data from BππB\to \pi \pi and BKπB\to K \pi. We also discuss SU(3) breaking effects from model estimate. We find that present data on Bππ,KπB\to \pi\pi, K \pi can also give some constraint on γ\gamma although weaker than the earlier method limited by the present experimental errors. Future improved data will provide more stringent constraint. Finally we perform a combined fit using data from ϵK|\epsilon_K|, ΔmBd,s\Delta m_{B_{d,s}}, Vub/Vcb|V_{ub}/V_{cb}|, sin2β\sin2\beta and rare charmless hadronic B decays. The combined analysis gives γ=67\gamma=67^\circ for the best fit value and 438743^\circ \sim 87^\circ as the 95% C.L. allowed range. Several comments on other methods to determine γ\gamma based on SU(3) symmetry are also provided.Comment: Revised verion with the new experimental data from Belle and Babar included in the analysis to obtain the global fit for the CP violating phase gamma. RevTex, 32 pages and 8 figure

    Bidirectional Thermo-Mechanical Properties of Foam Core Materials Using DIC

    Get PDF

    Development of Tailorable Electrically Conductive Thermal Control Material Systems

    Get PDF
    The optical characteristics of surfaces on spacecraft are fundamental parameters in controlling its temperature. Passive thermal control coatings with designed solar absorptance and infrared emittance properties have been developed and have been in use for some time. In this total space environment, the coating must be stable and maintain its desired optical properties as well as mechanical properties for the course of the mission lifetime. The mission lifetimes are increasing and in our quest to save weight, newer substrates are being integrated which limit electrical grounding schemes. All of this has added to already existing concerns about spacecraft charging and related spacecraft failures or operational failures. The concern is even greater for thermal control surfaces that are very large. One way of alleviating such concerns is to design new thermal control material systems (TCMS) that can help to mitigate charging via providing charge leakage paths. The objective of this program was to develop two types of passive electrically conductive TCMS. The first was a highly absorbing/emitting black surface and the second was a low (alpha(sub s)/epsilon(sub N)) type white surface. The surface resistance goals for the black absorber was 10(exp 4) to 10(exp 9) Omega/square, and for the white surfaces it was 10(exp 6) to 10(exp 10) Omega/square. Several material system concepts were suggested and evaluated for space environment stability and electrical performance characterization. Our efforts in designing and evaluating these material systems have resulted in several developments. New concepts, pigments and binders have been developed to provide new engineering quality TCMS. Some of these have already found application on space hardware, some are waiting to be recognized by thermal designers, and some require further detailed studies to become state-of-the-art for future space hardware and space structures. Our studies on baseline state-of-the-art materials and conductive concepts have resulted in several important findings that are of interest to all thermal designers and systems integrators

    Some Issues in a Gauge Model of Unparticles

    Full text link
    We address in a recent gauge model of unparticles the issues that are important for consistency of a gauge theory, i.e., unitarity and Ward identity of physical amplitudes. We find that non-integrable singularities arise in physical quantities like cross section and decay rate from gauge interactions of unparticles. We also show that Ward identity is violated due to the lack of a dispersion relation for charged unparticles although the Ward-Takahashi identity for general Green functions is incorporated in the model. A previous observation that the unparticle's (with scaling dimension d) contribution to the gauge boson self-energy is a factor (2-d) of the particle's has been extended to the Green function of triple gauge bosons. This (2-d) rule may be generally true for any point Green functions of gauge bosons. This implies that the model would be trivial even as one that mimics certain dynamical effects on gauge bosons in which unparticles serve as an interpolating field.Comment: v1:16 pages, 3 figures. v2: some clarifications made and presentation improved, calculation and conclusion not modified; refs added and updated. Version to appear in EPJ

    Bˉ0π+X\bar B^0 \to \pi^+ X in the Standard Model

    Full text link
    In this paper we investigate the possibility of studying BπB\to \pi form factor using the semi-inclusive decays Bˉ0π++Xq\bar B^0 \to \pi^+ + X_q. In general BPXB\to PX semi-inclusive decays involve several hadronic parameters. But for Bˉ0π+Xq\bar B^0 \to \pi^+ X_q decays we find that in the factorization approximation, the only unknown hadronic parameters are the form factors F0,1BπF^{B\to \pi}_{0,1}. Therefore these form factors can be studied in Bˉ0π+Xq\bar B^0 \to \pi^+ X_q decays. Using theoretical model calculations for the form factors the branching ratios for Bˉ0π+Xd(ΔS=0)\bar B^0 \to \pi^+ X_d(\Delta S = 0) and Bˉ0π+Xs(ΔS=1)\bar B^0 \to \pi^+ X_s (\Delta S = -1), with the cut Eπ>2.1E_{\pi} > 2.1 GeV, are estimated to be in the ranges of (3.14.9)×105(F1Bπ(0)/0.33)2(3.1\sim 4.9) \times 10^{-5}(F^{B\to \pi}_1(0)/0.33)^2 and (2.54.2)×105(F1Bπ(0)/0.33)2(2.5\sim 4.2)\times 10^{-5}(F_1^{B\to \pi}(0)/0.33)^2, respectively, depending on the value of γ\gamma. The combined branching ratio for Bˉ0π+(Xd+Xs)\bar B^0 \to \pi^+ (X_d+ X_s) is about 7.4×105(F1Bπ(0)/0.33)27.4\times 10^{-5} (F^{B\to \pi}_1(0)/0.33)^2 and is insensitive to γ\gamma. We also discuss CP asymmetries in these decay modes.Comment: RevTex 8 pages and two figure

    Semi-Inclusive B\to K(K^*) X Decays with Initial Bound State Effects

    Get PDF
    The effects of initial bb quark bound state for the semi-inclusive decays BK(K)XB\to K(K^*) X are studied using light cone expansion and heavy quark effective theory methods. We find that the initial bound state effects on the branching ratios and CP asymmetries are small. In the light cone expansion approach, the CP-averaged branching ratios are increased by about 2% with respect to the free bb-quark decay. For Bˉ0K(K)X\bar B^0 \to K^- (K^{*-}) X, the CP-averaged branching ratios are sensitive to the phase γ\gamma and the CP asymmetry can be as large as 7% (14%), whereas for BKˉ0(Kˉ0)XB^-\to \bar K^0 (\bar K^{*0})X the CP-averaged branching ratios are not sensitive to γ\gamma and the CP asymmetries are small (<1< 1%). The CP-averaged branching ratios are predicted to be in the ranges (0.531.5)×104(0.53 \sim 1.5)\times 10^{-4} [(0.252.0)×104(0.25 \sim 2.0)\times 10^{-4}] for Bˉ0K(K)X\bar B^0 \to K^- (K^{*-})X and (0.770.84)×104(0.77 \sim 0.84)\times 10^{-4} [(0.670.74)×104(0.67 \sim 0.74)\times 10^{-4}] for BKˉ0(Kˉ0)XB^-\to \bar K^0 (\bar K^{*0}) X, depending on the value of the CP violating phase γ\gamma. In the heavy quark effective theory approach, we find that the branching ratios are decreased by about 10% and the CP asymmetries are not affected. These predictions can be tested in the near future.Comment: 29 pages, 12 ps figure
    corecore