NLIE for hole excited states in the sine-Gordon model with two boundaries

We derive a nonlinear integral equation (NLIE) for some bulk excited states of the sine-Gordon model on a finite interval with general integrable boundary interactions, including boundary terms proportional to the first time derivative of the field. We use this NLIE to compute numerically the dimensions of these states as a function of scale, and check the UV and IR limits analytically. We also find further support for the ground-state NLIE by comparison with boundary conformal perturbation theory (BCPT), boundary truncated conformal space approach (BTCSA) and the boundary analogue of the Luscher formula.Comment: 31 pages, LaTeX; graphicx, epstopdf, 4 figure

The spectrum of tachyons in AdS/CFT

We analyze the spectrum of open strings stretched between a D-brane and an anti-D-brane in planar AdS/CFT using various tools. We focus on open strings ending on two giant gravitons with different orientation in $AdS_5 \times S^5$ and study the spectrum of string excitations using the following approaches: open spin-chain, boundary asymptotic Bethe ansatz and boundary thermodynamic Bethe ansatz (BTBA). We find agreement between a perturbative high order diagrammatic calculation in ${\cal N}=4$ SYM and the leading finite-size boundary Luscher correction. We study the ground state energy of the system at finite coupling by deriving and numerically solving a set of BTBA equations. While the numerics give reasonable results at small coupling, they break down at finite coupling when the total energy of the string gets close to zero, possibly indicating that the state turns tachyonic. The location of the breakdown is also predicted analytically.Comment: 40 pages, lots of figures, v2: typos corrected, accepted for publication in JHE

Unfolded Description of AdS4AdS_4 Kerr Black Hole

It is shown that $AdS_4$ Kerr black hole is a solution of simple unfolded differential equations that form a deformation of the zero-curvature description of empty $AdS_4$ space-time. Our construction uses the Killing symmetries of the Kerr solution. All known and some new algebraic properties of the Kerr-Schild solution result from the obtained black hole unfolded system in the coordinate-independent way. Kerr Schild type solutions of free equations in $AdS_4$ for massless fields of any spin, associated to the proposed black hole unfolded system, are found.Comment: 18 page

Systematic review of the scientific literature on the economic evaluation of cochlear implants in adult patients

A systematic review of the economic literature of cochlear implants (CI) was conducted with the aim of summarizing the results of studies on the cost effectiveness of monolateral and bilateral (sequential/simultaneous) CI in adult patients affected by severe to profound prelingual and postlingual hearing impairment. The literature search was performed using “PubMed MEDLINE” and the Centre for Reviews and Dissemination search engines. Inclusion criteria related to economic evaluation included primary studies published in English language from January 2000 to May 2010 and aimed to quantify costs of CI and compare monolateral CI vs. acoustic prosthesis and bilateral (sequential/ simultaneous) CI vs. monolateral CI in terms of cost per unit of effectiveness. Four articles were identified. The mean direct medical cost of the monolateral CI varied from € 30,026 to € 45,770 in postlingually deafened patients, and the cost of device represented the main cost component. Additional median costs of simultaneous and sequential bilateral CI were, respectively, € 21,831 and € 25,459. The mean direct medical cost of monolateral CI was € 31,942 in prelingually deafened patients. The monolateral CI in postlingually deafened patients represented a cost effective intervention as compared with no implant (€ /QALY varied from € 7,930, € 24,983 to € 33,094). Monolateral CI were not a cost effective intervention for traditional patients with more than 40 years of hearing impairment (€ 64,604/QALY ) or for patients with marginal benefits from using acoustic prosthesis with more than 30 years of hearing impairment (€ 106,267/QALY ). The cost effectiveness of monolateral CI worsened with increasing age (€ /QALY from € 23,439 for patients < 30 years old to € 55,369 for patients > 70 years). Bilateral CI in postlingually deafened patients were less cost effective than monolateral CI (from € 91,943/QALY to € 102,640/QALY ). Monolateral CI were cost effective in prelingually deafened patients (€ /QALY : € 8,096). Given the few economic evaluation studies in literature, future researches are needed to support the cost effectiveness results of CI in adults and to evaluate the cost effectiveness of bilateral CI, as well as to estimate the non-medical direct and indirect cost components

Systematic review of the scientific literature on the economic evaluation of cochlear implants in paediatric patients

The aim of the study consists in a systematic review concerning the economic evaluation of cochlear implant (CI) in children by searching the main international clinical and economic electronic databases. All primary studies published in English from January 2000 to May 2010 were included. The types of studies selected concerned partial economic evaluation, including direct and indirect costs of cochlear implantation; complete economic evaluation, including minimization of costs, cost-effectiveness analysis (CEA), cost-utility analysis (CUA) and cost-benefit analysis (CBA) performed through observational and experimental studies. A total of 68 articles were obtained from the database research. Of these, 54 did not meet the inclusion criteria and were eliminated. After reading the abstracts of the 14 articles selected, 11 were considered eligible. The articles were then read in full text. Furthermore, 5 articles identified by bibliography research were added manually. After reading 16 of the selected articles, 9 were included in the review. With regard to the studies included, countries examined, objectives, study design, methodology, prospect of analysis adopted, temporal horizon, the cost categories analyzed strongly differ from one study to another. Cost analysis, cost-effectiveness analysis and an analysis of educational costs associated with cochlear implants were performed. Regarding the cost analysis, only two articles reported both direct cost and indirect costs. The direct cost ranged between € 39,507 and € 68,235 (2011 values). The studies related to cost-effectiveness analysis were not easily comparable: one study reported a cost per QALY ranging between $5197 and$ 9209; another referred a cost of $2154 for QALY if benefits were not discounted, and$ 16,546 if discounted. Educational costs are significant, and increase with the level of hearing loss and type of school attended. This systematic review shows that the healthcare costs are high, but savings in terms of indirect and quality of life costs are also significant. Cochlear implantation in a paediatric age is cost-effective. The exiguity and heterogeneity of studies did not allow detailed comparative analysis of the studies included in the review

An HST Imaging Survey of Low-Mass Stars in the Chamaeleon I Star Forming region

We present new HST/WFPC2 observations of 20 fields centered around T Tauri stars in the Chamaeleon I star forming region. Images have been obtained in the F631N ([OI]6300A), F656N (Ha) and F673N ([SII]6716A+6731A) narrow-band filters, plus the Johnson V-band equivalent F547M filter. We detect 31 T Tauri stars falling within our fields. We discuss the optical morphology of 10 sources showing evidence of either binarity, circumstellar material, or mass loss. We supplement our photometry with a compilation of optical, infrared and sub-millimeter data from the literature, together with new sub-mm data for three objects, to build the Spectral Energy Distributions (SED) of 19 single sources. Using an SED model fitting tool, we self-consistently estimate a number of stellar and disk parameters, while mass accretion rates are directly derived from our Ha photometry. We find that bolometric luminosities derived from dereddened optical data tend to be underestimated in systems with high alpha(2-24} IR spectral index, suggesting that disks seen nearly edge-on may occasionally be interpreted as low luminosity (and therefore more evolved) sources. On the other hand, the same alpha(2-24) spectral index, a tracer of the amount of dust in the warmer layers of the circumstellar disks, and the mass accretion rate appear to decay with the isocronal stellar age, suggesting that the observed age spread (~0.5-5 Myr) within the cluster is real. Our sample contains a few outliers that may have dissipated their circumstellar disks on shorter time-scale.Comment: to appear on Astronomical Journal, accepted April 16, 2012 (AJ-10740

Triangle percolation in mean field random graphs -- with PDE

We apply a PDE-based method to deduce the critical time and the size of the giant component of the ``triangle percolation'' on the Erd\H{o}s-R\'enyi random graph process investigated by Palla, Der\'enyi and VicsekComment: Summary of the changes made: We have changed a remark about k-clique percolation in the first paragraph. Two new paragraphs are inserted after equation (4.4) with two applications of the equation. We have changed the names of some variables in our formula

Are There Age Spreads in Star Forming Regions?

A luminosity spread at a given effective temperature is ubiquitously seen in the Hertzsprung-Russell (HR) diagrams of young star forming regions and often interpreted in terms of a prolonged period (>=10 Myr) of star formation. I review the evidence that the observed luminosity spreads are genuine and not caused by astrophysical sources of scatter. I then address whether the luminosity spreads necessarily imply large age spreads, by comparing HR diagram ages with ages from independent clocks such as stellar rotation rate, the presence of circumstellar material and lithium depletion. I argue that whilst there probably is a true luminosity dispersion, there is little evidence to support age spreads larger than a few Myr. This paradox could be resolved by brief periods of rapid accretion during the class I pre main-sequence phase.Comment: To appear in the proceedings of JENAM10: Star Clusters in the Era of Large Surveys, 8 page