BPS and non-BPS states in a supersymmetric Landau-Ginzburg theory

We analyze the spectrum of the N=(2,2) supersymmetric Landau-Ginzburg theory in two dimensions with superpotential W=X^{n+2}-lambda X^2. We find the full BPS spectrum of this theory by exploiting the direct connection between the UV and IR limits of the theory. The computation utilizes results from the Picard-Lefschetz theory of singularities and its extension to boundary singularities. The additional fact that this theory is integrable requires that the BPS states do not close under scattering. This observation fixes the masses of non-BPS states as well.Comment: 27 pages, 12 figure

Avoidance of dental appointment due to cost and consequences for oral health-related quality of life: 25-yr follow-up of Swedish adults

We explored how socio-demographic and personal characteristics contribute to avoidance of dental appointment due to cost over time from age 55 (in 1997) to 75 (in 2017) and assessed the implications for oral health-related quality of life. In 1992, 6346 residents born in 1942 consented to participate in a prospective questionnaire survey, and 3060 (48.2%) of them completed postal follow-ups every fifth year until 2017. Oral health-related quality of life was assessed using the Oral Impact on Daily Performance inventory. The frequency of avoidance of dental appointment due to cost declined from 7.0% (in 1997) to 5.4% (in 2017), whereas the frequency of oral impacts declined from 26.0% in 2007 to 24.0% in 2017. Generalized Estimating Equation models revealed that avoidance of dental appointments due to cost was more likely reported in 1997 (OR: 1.5: 1.2–1.8) than in 2017, more likely in low educated people, and less likely in those using private dental care services. Avoidance of dental appointment due to cost was associated with impaired oral health-related quality of life. Social inequalities in avoidance of dental appointment due to cost and oral impacts did not vary across time but persisted into older ages despite the dental health care reforms that had been implemented.publishedVersio

Neurobehavioral function and low-level exposure to brominated flame retardants in adolescents : a cross-sectional study

Background: Animal and in vitro studies demonstrated a neurotoxic potential of brominated flame retardants, a group of chemicals used in many household and commercial products to prevent fire. Although the first reports of detrimental neurobehavioral effects in rodents appeared more than ten years ago, human data are sparse. Methods: As a part of a biomonitoring program for environmental health surveillance in Flanders, Belgium, we assessed the neurobehavioral function with the Neurobehavioral Evaluation System (NES-3), and collected blood samples in a group of high school students. Cross-sectional data on 515 adolescents (13.6-17 years of age) was available for the analysis. Multiple regression models accounting for potential confounders were used to investigate the associations between biomarkers of internal exposure to brominated flame retardants [serum levels of polybrominated diphenyl ether (PBDE) congeners 47, 99, 100, 153, 209, hexabromocyclododecane (HBCD), and tetrabromobisphenol A (TBBPA)] and cognitive performance. In addition, we investigated the association between brominated flame retardants and serum levels of FT3, FT4, and TSH. Results: A two-fold increase of the sum of serum PBDE's was associated with a decrease of the number of taps with the preferred-hand in the Finger Tapping test by 5.31 (95% CI: 0.56 to 10.05, p = 0.029). The effects of the individual PBDE congeners on the motor speed were consistent. Serum levels above the level of quantification were associated with an average decrease of FT3 level by 0.18 pg/mL (95% CI: 0.03 to 0.34, p = 0.020) for PBDE-99 and by 0.15 pg/mL (95% CI: 0.004 to 0.29, p = 0.045) for PBDE-100, compared with concentrations below the level of quantification. PBDE-47 level above the level of quantification was associated with an average increase of TSH levels by 10.1% (95% CI: 0.8% to 20.2%, p = 0.033), compared with concentrations below the level of quantification. We did not observe effects of PBDE's on neurobehavioral domains other than the motor function. HBCD and TBBPA did not show consistent associations with performance in the neurobehavioral tests. Conclusions: This study is one of few studies and so far the largest one investigating the neurobehavioral effects of brominated flame retardants in humans. Consistently with experimental animal data, PBDE exposure was associated with changes in the motor function and the serum levels of the thyroid hormones

A Shock-Patching Code for Ultra-Relativistic Fluid Flows

We have developed a one-dimensional code to solve ultra-relativistic hydrodynamic problems, using the Glimm method for an accurate treatment of shocks and contact discontinuities. The implementation of the Glimm method is based on an exact Riemann solver and van der Corput sampling sequence. In order to improve computational efficiency, the Glimm method is replaced by a finite differencing scheme in those regions where the fluid flow is sufficiently smooth. The accuracy and convergence of this hybrid method is investigated in tests involving planar, cylindrically and spherically symmetric flows that exhibit strong shocks and Lorentz factors of up to ~2000. This hybrid code has proven to be successful in simulating the interaction between a thin, ultra-relativistic, spherical shell and a low density stationary medium, a situation likely to appear in Gamma-Ray Bursts, supernovae explosions, pulsar winds and AGNs.Comment: submitted to ApJ, in press, Latex, uses AAS macro aaspp4.sty and psfig.tex (version 1.9), 12 pages, 5 figures and 4 tables, revised version (more detailed description of the numerical implementation of the Glimm method

Infinite spin limit of semiclassical string states

Motivated by recent works of Hofman and Maldacena and Dorey we consider a special infinite spin limit of semiclassical spinning string states in AdS5 x S5. We discuss examples of known folded and circular 2-spin string solutions and demonstrate explicitly that the 1-loop superstring correction to the classical expression for the energy vanishes in the limit when one of the spins is much larger that the other. We also give a general discussion of this limit at the level of integral equations describing finite gap solutions of the string sigma model and argue that the corresponding asymptotic form of the string and gauge Bethe equations is the same.Comment: 38 pages, 3 figures; v2: comments on derivation of bound states of magnons from discrete Bethe equations added in section 4 and appendix C, references added, Imperial-TP-AT-6-4, HUTP-06/A002

Shark-diving tourism as a financing mechanism for shark conservation strategies in Malaysia

This study estimated the economic value of the shark-diving industry in Semporna, the most popular diving destination of Malaysia, by surveying the expenditures of diving tourists and dive operators through the region. A willingness-to-pay survey was also used to estimate the potential of the industry as a financing mechanism for enforcement and management of a hypothetical Marine Protected Area (MPA) to conserve shark populations. The study showed that in 2012, shark-diving tourism provided direct revenues in excess of USD 9.8 million to the Semporna region. These economic benefits had a flow-on effect, generating more than USD 2 million in direct taxes to the government and USD 1.4 million in salaries to the community. A contingent valuation analysis indicated that implementation of a fee paid by divers could generate over USD 2 million for management and enforcement of the MPA each year. These findings suggest that shark diving is an important contributor to the economy of the Semporna region that could be used as a mechanism to assist financial resourcing for management and conservation strategies

Underwater adhesive using solid–liquid polymer mixes

Instantaneous adhesion between different materials is a requirement for several applications ranging from electronics to biomedicine. Approaches such as surface patterning, chemical cross-linking, surface modification, and chemical synthesis have been adopted to generate temporary adhesion between various materials and surfaces. Because of the lack of curing times, temporary adhesives are instantaneous, a useful property for specific applications that need quick bonding. However, to this day, temporary adhesives have been mainly demonstrated under dry conditions and do not work well in submerged or humid environments. Furthermore, most rely on chemical bonds resulting from strong interactions with the substrate such as acrylate based. This work demonstrates the synthesis of a universal amphibious adhesive solely by combining solid polytetrafluoroethylene (PTFE) and liquid polydimethylsiloxane (PDMS) polymers. While the dipole-dipole interactions are induced by a large electronegativity difference between fluorine atoms in PTFE and hydrogen atoms in PDMS, strong surface wetting allows the proposed adhesive to fully coat both substrates and PTFE particles, thereby maximizing the interfacial chemistry. The two-phase solid–liquid polymer system displays adhesive characteristics applicable both in air and water, and enables joining of a wide range of similar and dissimilar materials (glasses, metals, ceramics, papers, and biomaterials). The adhesive exhibits excellent mechanical properties for the joints between various surfaces as observed in lap shear testing, T-peel testing, and tensile testing. The proposed biocompatible adhesive can also be reused multiple times in different dry and wet environments. Additionally, we have developed a new reactive force field parameterization and used it in our molecular dynamics simulations to validate the adhesive nature of the mixed polymer system with different surfaces. This simple amphibious adhesive could meet the need for a universal glue that performs well with a number of materials for a wide range of conditions

Lassoing and corraling rooted phylogenetic trees

The construction of a dendogram on a set of individuals is a key component of a genomewide association study. However even with modern sequencing technologies the distances on the individuals required for the construction of such a structure may not always be reliable making it tempting to exclude them from an analysis. This, in turn, results in an input set for dendogram construction that consists of only partial distance information which raises the following fundamental question. For what subset of its leaf set can we reconstruct uniquely the dendogram from the distances that it induces on that subset. By formalizing a dendogram in terms of an edge-weighted, rooted phylogenetic tree on a pre-given finite set X with |X|>2 whose edge-weighting is equidistant and a set of partial distances on X in terms of a set L of 2-subsets of X, we investigate this problem in terms of when such a tree is lassoed, that is, uniquely determined by the elements in L. For this we consider four different formalizations of the idea of "uniquely determining" giving rise to four distinct types of lassos. We present characterizations for all of them in terms of the child-edge graphs of the interior vertices of such a tree. Our characterizations imply in particular that in case the tree in question is binary then all four types of lasso must coincide