847 research outputs found

    Control of Ascaris infection by chemotherapy: which is the most cost-effective option?

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    Cost-effectiveness analysis is used to predict the optimal design of mass chemotherapy strategies in controlling Ascaris lumbricoides infection. The question of who to treat, how many to treat, and how often to treat are addressed using a population dynamic model of helminth transmission that assesses effectiveness in terms of disease reduction, combined with cost data from an actual control programme. Child-targeted treatment can be more cost-effective than population treatment in reducing the number of disease cases. The model also implies that, in the circumstances described here, enhancing coverage is a more cost-effective approach than increasing frequency of treatmen

    Improved bounds for speed scaling in devices obeying the cube-root rule

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    Speed scaling is a power management technology that involves dynamically changing the speed of a processor. This technology gives rise to dual-objective scheduling problems, where the operating system both wants to conserve energy and optimize some Quality of Service (QoS) measure of the resulting schedule. In the most investigated speed scaling problem in the literature, the QoS constraint is deadline feasibility, and the objective is to minimize the energy used. The standard assumption is that the processor power is of the form s^a where s is the processor speed, and a>1 is some constant; a˜3 for CMOS based processors. In this paper we introduce and analyze a natural class of speed scaling algorithms, that we call qOA. The algorithm qOA sets the speed of the processor to be q times the speed that the optimal offline algorithm would run the jobs in the current state. When a=3, we show that qOA is 6.7-competitive, improving upon the previous best guarantee of 27 achieved by the algorithm Optimal Available (OA). We also give almost matching upper and lower bounds for qOA for general a. Finally, we give the first non-trivial lower bound, namely e^(a-1) / a, on the competitive ratio of a general deterministic online algorithm for this problem

    String Indexing for Patterns with Wildcards

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    We consider the problem of indexing a string tt of length nn to report the occurrences of a query pattern pp containing mm characters and jj wildcards. Let occocc be the number of occurrences of pp in tt, and σ\sigma the size of the alphabet. We obtain the following results. - A linear space index with query time O(m+σjloglogn+occ)O(m+\sigma^j \log \log n + occ). This significantly improves the previously best known linear space index by Lam et al. [ISAAC 2007], which requires query time Θ(jn)\Theta(jn) in the worst case. - An index with query time O(m+j+occ)O(m+j+occ) using space O(σk2nlogklogn)O(\sigma^{k^2} n \log^k \log n), where kk is the maximum number of wildcards allowed in the pattern. This is the first non-trivial bound with this query time. - A time-space trade-off, generalizing the index by Cole et al. [STOC 2004]. We also show that these indexes can be generalized to allow variable length gaps in the pattern. Our results are obtained using a novel combination of well-known and new techniques, which could be of independent interest

    Genome-wide Association Study Identifies Genetic Variants Associated With Early and Sustained Response to (Pegylated) Interferon in Chronic Hepatitis B Patients: The GIANT-B Study

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    Background. (Pegylated) Interferon ([Peg]IFN) therapy leads to response in a minority of chronic hepatitis B (CHB) patients. Host genetic determinants of response are therefore in demand. Methods. In this genome-wide association study (GWAS), CHB patients, treated with (Peg)IFN for at least 12 weeks ± nucleos(t)ide analogues within randomized trials or as standard of care, were recruited at 21 centers from Europe, Asia, and North America. Response at 24 weeks after (Peg)IFN treatment was defined as combined hepatitis B e antigen (HBeAg) loss with hepatitis B virus (HBV) DNA <2000 IU/mL, or an HBV DNA <2000 IU/mL for HBeAg-negative patients. Results. Of 1144 patients, 1058 (92%) patients were included in the GWAS analysis. In total, 282 (31%) patients achieved the response and 4% hepatitis B surface antigen (HBsAg) loss. GWAS analysis stratified by HBeAg status, adjusted for age, sex, and the 4 ancestry components identified PRELID2 rs371991 (B= −0.74, standard error [SE] = 0.16, P = 3.44 ×10–6) for HBeAg-positive patients. Importantly, PRELID2 was cross-validated for long-term response in HBeAg-negative patients. G3BP2 rs3821977 (B = 1.13, SE = 0.24, P = 2.46 × 10–6) was associated with response in HBeAg-negative patients. G3BP2 has a role in the interferon pathway and was further examined in peripheral blood mononuclear cells of healthy controls stimulated with IFNα and TLR8. After stimulation, less production of IP-10 and interleukin (IL)-10 proteins and more production of IL-8 were observed with the G3BP2 G-allele. Conclusions. Although no genome-wide significant hits were found, the current GWAS identified genetic variants associated with (Peg)IFN response in CHB. The current findings could pave the way for gene polymorphism-guided clinical counseling, both in the setting of (Peg)IFN and the natural history, and possibly for new immune-modulating therapies

    Donor Centers and Absorption Spectra in Quantum Dots

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    We have studied the electronic properties and optical absorption spectra of three different cases of donor centers, D^{0}, D^{-} and D^{2-}, which are subjected to a perpendicular magnetic field, using the exact diagonalization method. The energies of the lowest lying states are obtained as function of the applied magnetic field strength B and the distance zeta between the positive ion and the confinement xy-plane. Our calculations indicate that the positive ion induces transitions in the ground-state, which can be observed clearly in the absorption spectra, but as zeta goes to 0 the strength of the applied magnetic field needed for a transition to occur tends to infinity.Comment: 5 pages, 4 figures, REVTeX 4, gzipped tar fil

    New Lymphogranuloma Venereum Chlamydia trachomatis Variant, Amsterdam

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    We retrospectively conducted a study of men who have sex with men who visited the Amsterdam, the Netherlands, sexually transmitted diseases clinic from January 2002 to December 2003 and had rectal Chlamydia trachomatis infections. We found that symptomatic (73%) as well as asymptomatic (43%) patients were infected with a new C. trachomatis LGV variant

    SARS Coronavirus Detection Methods

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    Using clinical samples from patients with severe acute respiratory syndrome, we showed that the sensitivities of a quantitative reverse transcription–polymerase chain reaction (80% for fecal samples and 25% for urine samples) were higher than those of the polyclonal (50% and 5%) and monoclonal (35% and 8%) antibody-based nucleocapsid antigen capture enzyme-linked immunosorbent assays

    Focus Point SUSY at the LHC Revisited

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    The estimation of the backgrounds for gluino signals in focus point supersymmetry is extended by including the backgrounds from the production of four third generation quarks in the analysis. We find that these backgrounds are negligible if one uses the strong selection criteria proposed in the literature (including this analysis) for heavy gluino searches. Softer selection criteria often recommended for lighter gluino searches yield backgrounds which are small but numerically significant. We have also repeated the more conventional background calculations and compared our results with the other groups. We find that the size of the total residual background estimated by different groups using different event generators and hard kinematical cuts agree approximately. In view of the theoretical uncertainties in the leading order signal and background cross sections mainly due to the choice of the QCD scale, the gluino mass reach at the LHC cannot be pinpointed. However, requiring a signal with 3\rm\geq 3 tagged b-jets (instead of the standard choice of 2\rm\geq 2) it is shown that gluino masses close to 2 TeV can be probed at the LHC for a range of reasonable choices of the QCD scale for an integrated luminosity of 300 fb1^{-1}.Comment: 17 pages, 4 figures, minor typos correctio
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