Electrostatic image effects for counter-ions between charged planar walls

We study the effect of dielectric inhomogeneities on the interaction between two planparallel charged surfaces with oppositely charged mobile charges in between. The dielectric constant between the surfaces is assumed to be different from the dielectric constant of the two semiinfinite regions bounded by the surfaces, giving rise to electrostatic image interactions. We show that on the weak coupling level the image charge effects are generally small, making their mark only in the second order fluctuation term. However, in the strong coupling limit, the image effects are large and fundamental. They modify the interactions between the two surfaces in an essential way. Our calculations are particularly useful in the regime of parameters where computer simulations would be difficult and extremely time consuming due to the complicated nature of the long range image potentials.Comment: 21 pages, 8 figure

Remarks on Limits on String Scale from Proton Decay and Low-Energy amplitudes in Braneworld Scenario

We discuss IR limit of four-fermion scattering amplitudes in braneworld models including intersecting-branes and SUSY SU(5) GUT version of it. With certain compactification where instanton effect is negligible, grand unification condition in D6-D6 intersecting-branes scenario subject to experimental constraint on proton decay provides possibility for upper limit on the string scale, $M_S$, through relationship between the string coupling, $g_s$, and the string scale. We discuss how IR divergence is related to number of twisted fields we have to introduce into intersection region and how it can change IR behaviour of tree-level amplitudes in various intersecting-branes models. Using number of twisted fields, we identify some intersecting-branes models whose tree-level amplitudes are purely stringy in nature and automatically proportional to $g_s/M^2_{S}$ at low energy. They are consequently suppressed by the string scale. For comparison, we also derive limit on the lower bound of the string scale from experimental constraint on proton decay induced from purely stringy contribution in the coincident-branes model, the limit is about $10^5$ TeV.Comment: 14 page

The Electronics and Data Acquisition System of the DarkSide Dark Matter Search

It is generally inferred from astronomical measurements that Dark Matter (DM) comprises approximately 27\% of the energy-density of the universe. If DM is a subatomic particle, a possible candidate is a Weakly Interacting Massive Particle (WIMP), and the DarkSide-50 (DS) experiment is a direct search for evidence of WIMP-nuclear collisions. DS is located underground at the Laboratori Nazionali del Gran Sasso (LNGS) in Italy, and consists of three active, embedded components; an outer water veto (CTF), a liquid scintillator veto (LSV), and a liquid argon (LAr) time projection chamber (TPC). This paper describes the data acquisition and electronic systems of the DS detectors, designed to detect the residual ionization from such collisions

R&D on co-working transport schemes in Geant4

A research and development (R&D) project related to the extension of the Geant4 toolkit has been recently launched to address fundamental methods in radiation transport simulation. The project focuses on simulation at different scales in the same experimental environment; this problem requires new methods across the current boundaries of condensed-random-walk and discrete transport schemes. The new developments have been motivated by experimental requirements in various domains, including nanodosimetry, astronomy and detector developments for high energy physics applications.Comment: To be published in the Proceedings of the CHEP (Computing in High Energy Physics) 2009 conferenc

The articulation of enkinaesthetic entanglement

In this article I present an argument for the necessary co-articulation of meaning within our felt enkinaesthetic engagement with our world. The argument will be developed through a series of stages, the first of which will be an elaboration of the notion of articulation of and through the body. This will be followed by an examination of enkinaesthetic experiential entanglement and the role it plays in rendering our world meaningful and our actions values-realising. At this stage I will begin to extend Husserl’s notion of intentional transgression to the enkinaesthetic sphere of lived experience, and in support of this claim I will examine the theoretical and practical work of osteopathic manual listening [Gens & Roche 2014] and the ‘felt sense’ in focusing [Gendlin] which makes possible a shift from a somatic articulation to a semantic, and potentially conceptual, one. Throughout, my position will be compatible with Merleau-Ponty’s claim that “Whenever I try to understand myself, the whole fabric of the perceptible world comes too, and with it comes the others who are caught in it.” [Merleau-Ponty 1964a, p.15]

Baseline natural killer and T cell populations correlation with virologic outcome after regimen simplification to atazanavir/ritonavir alone (ACTG 5201).

OBJECTIVES: Simplified maintenance therapy with ritonavir-boosted atazanavir (ATV/r) provides an alternative treatment option for HIV-1 infection that spares nucleoside analogs (NRTI) for future use and decreased toxicity. We hypothesized that the level of immune activation (IA) and recovery of lymphocyte populations could influence virologic outcomes after regimen simplification. METHODS: Thirty-four participants with virologic suppression ≥ 48 weeks on antiretroviral therapy (2 NRTI plus protease inhibitor) were switched to ATV/r alone in the context of the ACTG 5201 clinical trial. Flow cytometric analyses were performed on PBMC isolated from 25 patients with available samples, of which 24 had lymphocyte recovery sufficient for this study. Assessments included enumeration of T-cells (CD4/CD8), natural killer (NK) (CD3+CD56+CD16+) cells and cell-associated markers (HLA-DR, CD\u27s 38/69/94/95/158/279). RESULTS: Eight of the 24 patients had at least one plasma HIV-1 RNA level (VL) \u3e50 copies/mL during the study. NK cell levels below the group median of 7.1% at study entry were associated with development of VL \u3e50 copies/mL following simplification by regression and survival analyses (p = 0.043 and 0.023), with an odds ratio of 10.3 (95% CI: 1.92-55.3). Simplification was associated with transient increases in naïve and CD25+ CD4+ T-cells, and had no impact on IA levels. CONCLUSIONS: Lower NK cell levels prior to regimen simplification were predictive of virologic rebound after discontinuation of nucleoside analogs. Regimen simplification did not have a sustained impact on markers of IA or T lymphocyte populations in 48 weeks of clinical monitoring. TRIAL REGISTRATION: ClinicalTrials.gov NCT00084019

Validity of home-based sonographic diagnosis of obstetric risk factors by auxiliary nurse midwives in rural Nepal

Background Approximately 2·3 million fetal, neonatal, or maternal deaths occur annually during the intrapartum period or on the day of birth. Several risk factors for intrapartum-related complications require ultrasonography for accurate diagnosis, but sonographic services are scarce in low-resource settings. In this study, we aimed to assess the feasibility of community-based ultrasonography conducted by auxiliary nurse midwives to identify basic obstetric risk factors, in rural Sarlahi District, Nepal. We aimed to assess the validity at which these health workers can detect noncephalic position, multiple gestation, and placenta previa and to explore whether sonographic diagnosis could improve outcomes for women with these high-risk conditions. Methods Three auxiliary nurse midwives (ANM) received two 1-week ultrasound trainings at Tribhuvan University Teaching Hospital in Kath mandu, Nepal. Women at 32 weeks’ or more gestation were enrolled in the study, and received ultrasonography from the ANMs during home visits. ANMs used ultrasonography to identify non-cephalic position, multiple gestation, and placenta previa. Images were saved and later reassessed by gold standard ultrasonographers to determine the validity of the ANM assessment. We also compared adverse outcomes in noncephalic or multiple gestation births from the study group with those in a comparison group of women who did not receive ultrasonography from our study, but the study was not powered to detect a difference. Findings We collected data from 815 women. The kappa statistics for diagnosis of non-cephalic position were 0·92, 0·98, and 0·94, respectively, for the three ANMs against the gold standard. Sensitivity, specificity, positive predictive value, and negative predictive value were between 90% and 100% for all ANMs. For multiple gestation pregnancies (n=6), the ANMs were in perfect agreement with both the gold standard reading and maternal postpartum self-report. Two cases of placenta previa were detected, and the gold standard was in agreement with both. There were 4 adverse outcomes out of 19 women (21%) with non-cephalic or multiple gestation pregnancies in the study group compared with 10 out of 36 (28%) in the comparison group. This difference was not significant (p=0·586). Interpretation Our findings suggest that it is feasible for ANMs to conduct ultrasonography to identify basic obstetric risk factors in low-income settings. The difference in birth outcomes in non-cephalic and multiple births, comparing those antenatally diagnosed by ultrasound and those who were not, was not significant; the sample size was too small to detect a diff erence. Further investigation is warranted to determine whether sonographic diagnosis of selected obstetric factors could contribute to improved care-seeking and health outcomes in low-income settings. Funding Cappsci Data for Life Award, SonoSite Soundcaring Program, National Institutes of Health/National Institute of Child Health and Human Development, Bill & Melinda Gates Foundation