691 research outputs found

    A Longitudinal Study of Streptococcus mutans Colonization in Infants after Tooth Eruption

    Get PDF
    We previously reported that, before tooth eruption, over one-half of infants aged 6 mos were already infected with Streptococcus mutans. The aim of this investigation was to determine the colonization of S. mutans after tooth eruption in the same cohort of 111 infants (35 pre-term, 76 full-term). Our results showed that S. mutans colonization increased with increasing age, so that by 24 mos of age, 84% harbored the bacteria (p 10(5) CFU/mL (p < 0.02). In contrast, non-colonization of S. mutans was associated with toothbrushing (p < 0.03) and multiple courses of antibiotics (p < 0.001). Analysis of our data establishes the timing of S. mutans colonization in children from birth to 24 mos of age

    Longitudinal Current Dissipation in Bose-glass Superconductors

    Full text link
    A scaling theory of vortex motion in Bose glass superconductors with currents parallel to the common direction of the magnetic field and columnar defects is presented. Above the Bose-glass transition the longitudinal DC resistivity ρ(T)(TTBG)νz\rho_{||}(T)\sim (T-T_{BG})^{\nu' z'} vanishes much faster than the corresponding transverse resistivity ρ(T)(TTBG)ν(z2)\rho_{\perp}(T)\sim (T-T_{BG})^{\nu' (z'-2)}, thus {\it reversing} the usual anisotropy of electrical transport in the normal state of layered superconductors. In the presence of a current J\bf J at an angle θJ\theta_J with the common field and columnar defect axis, the electric field angle θE\theta_E approaches π/2\pi/2 as TTBG+T\rightarrow T_{BG}^+. Scaling also predicts the behavior of penetration depths for the AC currents as TTBGT\rightarrow T_{BG}^-, and implies a {\it jump discontinuity} at TBGT_{BG} in the superfluid density describing transport parallel to the columns.Comment: 5 pages, revte

    Distributed Supervisory Control of Discrete-Event Systems with Communication Delay

    Full text link
    This paper identifies a property of delay-robustness in distributed supervisory control of discrete-event systems (DES) with communication delays. In previous work a distributed supervisory control problem has been investigated on the assumption that inter-agent communications take place with negligible delay. From an applications viewpoint it is desirable to relax this constraint and identify communicating distributed controllers which are delay-robust, namely logically equivalent to their delay-free counterparts. For this we introduce inter-agent channels modeled as 2-state automata, compute the overall system behavior, and present an effective computational test for delay-robustness. From the test it typically results that the given delay-free distributed control is delay-robust with respect to certain communicated events, but not for all, thus distinguishing events which are not delay-critical from those that are. The approach is illustrated by a workcell model with three communicating agents

    The effects of chlorhexidine gel on Streptococcus mutans infection in 10-month-old infants: A longitudinal, placebo-controlled, double-blind trial

    Get PDF
    This study investigated the long-term effects of 0.2% chlorhexidine gel, used as a weekly brush-on gel, on Streptoccocus mutans infection in 10-month-old infants.The investigation followed the criteria of a placebo-controlled, double-blind, longitudinal clinical trial. Infants were recruited at birth and oral microbiological swabs were taken at 3 monthly intervals, together with medical, dental, dietary and brushing histories. Children who were found to be colonized with S. mutans were randomly assigned to either the chlorhexidine-gel group (N = 50) or placebo gel group (N = 46), and parents were instructed to brush the gel on the teeth once per week for 12 weeks. In another control group (N = 210), infants did not use either chlorhexidine or placebo gels. Saliva samples were cultured using S. mutans-selective tryptone-yeast extract-cysteine-sucrose-bacitracin (TYCSB) agar. The mean age of the children was 10.2 +/- 2.6 months at the start of the trial and subjects were followed until the ages of 18 months.In the children with initial low S. mutans counts of < 300 CFU/mL, there was a significant percentage reduction in S. mutans counts in the chlorhexidine-gel group compared to the placebo gel and no-gel control groups after 3 months of weekly gel brushing. However, no significant differences with the placebo group were observed after 15 months of follow-up. There were 39 children (41%) who achieved reduction of their S. mutans to 0 CFU/mL. Compared to those who remained infected with S. mutans, these children had higher toothbrushing frequencies (P < .001) and toothpaste use (P < .001), as well as lower frequencies of daily feeds (P < .01), and lesser weekly frequencies of sweet solids and liquids (P < .001).Children with relatively low initial S. mutans counts (< 300 CFU/mL) showed a reduction in S. mutans counts in the first 3 months when 0.2% chlorhexidine gel was brushed on the teeth weekly. No differences were observed when compared with the placebo and no-treatment groups at later follow-up periods

    Melting of Flux Lines in an Alternating Parallel Current

    Full text link
    We use a Langevin equation to examine the dynamics and fluctuations of a flux line (FL) in the presence of an {\it alternating longitudinal current} J(ω)J_{\parallel}(\omega). The magnus and dissipative forces are equated to those resulting from line tension, confinement in a harmonic cage by neighboring FLs, parallel current, and noise. The resulting mean-square FL fluctuations are calculated {\it exactly}, and a Lindemann criterion is then used to obtain a nonequilibrium `phase diagram' as a function of the magnitude and frequency of J(ω)J_{\parallel}(\omega). For zero frequency, the melting temperature of the mixed phase (a lattice, or the putative "Bose" or "Bragg Glass") vanishes at a limiting current. However, for any finite frequency, there is a non-zero melting temperature.Comment: 5 pages, 1 figur

    Soy intake and breast cancer risk in Singapore Chinese Health Study

    Get PDF
    We investigated the effects of soy isoflavone intake on breast cancer in a prospective study of 35 303 Singapore Chinese women enrolled during April 1993 to December 1998 in the Singapore Chinese Health Study. At recruitment, each subject was personally administered a validated semiquantitative food frequency questionnaire covering 165 food and beverage items. As of December 31 2005, 629 had developed breast cancer following an accumulation of 338 242 person-years. Using Cox regression and adjusting for age at interview, year of interview, dialect group, education, family history of breast cancer, age when periods became regular, parity, menopausal status, body mass index (BMI), n-3 fatty acid, and other covariates, we found breast cancer risk was reduced significantly in association with high soy intake. Relative to women with lower (below median) soy intake (<10.6 mg isoflavone per 1000 Kcal), women with higher (above median) intake showed a significant 18% risk reduction (relative risk (RR)=0.82, 95% confidence interval (CI)=0.70–0.97). This inverse association was apparent mainly in postmenopausal women (RR=0.74, 95% CI=0.61–0.90), and was not observed in premenopausal women (RR=1.04, 95% CI=0.77–1. 40). Among postmenopausal women, the soy–breast cancer association was stronger in those above median BMI (RR=0.67, 95% CI=0.51–0.88) than in leaner women (RR=0.83, 95% CI=0.62–1.11). Duration of follow-up modified the soy–breast cancer association, the effect being twice as large among women with 10+ vs fewer years of follow-up. Neither oestrogen nor progesterone receptor status of the tumours materially influenced the association. These prospective findings suggest that approximately 10 mg of isoflavones per day, obtained in a standard serving of tofu, may have lasting beneficial effects against breast cancer development

    Female trauma patients in the emergency department: should their injury prevention programme be different?

    Get PDF
    Background: (1) To compare the characteristics of female and male trauma patients seen in the Emergency Department (ED) and (2) to determine if injury prevention programmes for women should be different. Methods: A prospective survey was conducted for 11544 trauma patients, aged 15 years and above, who presented to the ED of an urban public hospital in Singapore over 6 months. The following data were collected: demography, place, type and mechanism of injury and subsequent disposition from the ED. Results: Almost half (49.5%) the injuries sustained by females occurred at home, with low falls of less than 2 metres being the most common mechanism of injury (52.7%). Victims of domestic violence were predominantly female at p&lt;0.0001
    corecore