A scaled difference chi-square test statistic for moment structure analysis

A family of scaling corrections aimed to improve the chi-square approximation of goodness-of-fit test statistics in small samples, large models, and nonnormal data was proposed in Satorra and Bentler (1994). For structural equations models, Satorra-Bentler's (SB) scaling corrections are available in standard computer software. Often, however, the interest is not on the overall fit of a model, but on a test of the restrictions that a null model say ${\cal M}_0$ implies on a less restricted one ${\cal M}_1$. If $T_0$ and $T_1$ denote the goodness-of-fit test statistics associated to ${\cal M}_0$ and ${\cal M}_1$, respectively, then typically the difference $T_d = T_0 - T_1$ is used as a chi-square test statistic with degrees of freedom equal to the difference on the number of independent parameters estimated under the models ${\cal M}_0$ and ${\cal M}_1$. As in the case of the goodness-of-fit test, it is of interest to scale the statistic $T_d$ in order to improve its chi-square approximation in realistic, i.e., nonasymptotic and nonnormal, applications. In a recent paper, Satorra (1999) shows that the difference between two Satorra-Bentler scaled test statistics for overall model fit does not yield the correct SB scaled difference test statistic. Satorra developed an expression that permits scaling the difference test statistic, but his formula has some practical limitations, since it requires heavy computations that are notavailable in standard computer software. The purpose of the present paper is to provide an easy way to compute the scaled difference chi-square statistic from the scaled goodness-of-fit test statistics of models ${\cal M}_0$ and ${\cal M}_1$. A Monte Carlo study is provided to illustrate the performance of the competing statistics.

Closure of the Monte Carlo dynamical equation in the spherical Sherrington-Kirkpatrick model

We study the analytical solution of the Monte Carlo dynamics in the spherical Sherrington-Kirkpatrick model using the technique of the generating function. Explicit solutions for one-time observables (like the energy) and two-time observables (like the correlation and response function) are obtained. We show that the crucial quantity which governs the dynamics is the acceptance rate. At zero temperature, an adiabatic approximation reveals that the relaxational behavior of the model corresponds to that of a single harmonic oscillator with an effective renormalized mass.

Bilateral anterior pubic osteotomy in bladder exstrophy closure.

PURPOSE: We report our clinical experience with anterior pelvic osteotomy in 16 patients who underwent surgery for bladder exstrophy. The technique and its difficulties are discussed. MATERIALS AND METHODS: Anterior pelvic osteotomy of the superior ramus of the public bone is a simple and efficient method to facilitate symphyseal approximation and abdominal wall closure without or with low tension on the suture lines in neonates who undergo surgery for bladder exstrophy. Older children in whom surgery has been delayed can also benefit from this method. Compared to other methods of osteotomy in exstrophy surgery it does not require additional incisions, nor does the patient need to be repositioned on the operating table. A successful operation does not depend on any particular orthopedic skills and it can easily be done by the pediatric urologist. RESULTS: Immediate postoperative results regarding abdominal wall closure were excellent in all 16 patients. However, major postoperative complications developed in 2 patients. Despite antibiotic prophylaxis a severe soft tissue infection developed in 1 child, resulting in complete bladder dehiscence. In another patient an obturator nerve injury resulted in transient palsy, which resolved completely. While the first complication was not related to osteotomy, the second was osteotomy related. CONCLUSIONS: Bilateral superior ramotomy of the pubic bones is a new alternative, easily performed technique to optimize bladder exstrophy surgery in children.

Labor market experience and well-being after firm closure. Survey evidence on displaced manufacturing workers in Switzerland

This study examines how plant closure affected individuals' careers and lives about two years after they lost their job. We analyze the displaced workers' reemployment prospects and study for reemployed workers the characteristics of their new jobs in terms of reemployment sectors, wages, and job quality. Additionally, we inquire how workers' sociability and subjective well-being were affected by job loss. Our analysis is based on our own survey conducted in Switzerland in 2011. The survey included the workforce of five manufacturing companies that had closed down two years earlier. We addressed the risk of biases typically prevailing with observational data by complementing it with register data from the public unemployment insurance. Moreover, we use a control group based on matched data from the Swiss Household Panel. We find that workers experience strongly diverging outcomes after plant closure: on the one hand, high proportions of the workers experience a smooth transition after plant closure. More than two-thirds of the workers returned to employment, more than half of them within less than six months. With respect to their social lives, we find that positive changes in relationships with their spouse, family and friends are more frequent than negative changes. On the other hand, for a small group of workers plant closure had a detrimental effect. Close to twenty percent remained unemployed. About ten percent of the workers were long-term unemployed and subsequently often were reemployed in jobs of lower quality. Unemployed workers and workers who dropped out of the labor force were particularly prone to find their subjective well-being decreasing. The most vulnerable subgroup in our study were workers over 55. This result stands in striking contrast to a large body of literature that considers labor market institutions to be primarily biased against young workers. Our findings show that older workers not only take longer to find a job but are also less likely to return to employment. Moreover, if they manage to find a job, they experience the severest cuts in wages and job quality of all cohorts. From a life-course perspective this result is remarkable since it shows that workers are not protected from hardship in their late careers. In light of the current demographic changes this finding may have important policy implications. -- Cette étude analyse l'impact des fermetures d'entreprises sur les travailleurs licenciés. Plus précisément, nous examinons les chances de réinsertion des travailleurs dans le marché du travail et - pour ceux qui l'ont fait avec succès - dans quels secteurs, pour quels salaires et avec quelle qualité d'emploi ils sont réengagés. Nous nous intéressons également aux répercussions engendrées par la perte de l'emploi sur la sociabilité et le bien-être subjectif des travailleurs concernés. Notre analyse se base sur les données d'une enquête que nous avons menée en 2011. Cette enquête cible le personnel de cinq entreprises industrielles suisses qui avaient fermé leurs portes deux ans auparavant. Pour dépasser les biais typiques liés aux données d'observation, nous utilisons en complément des données administratives issues de l'assurance chômage publique. De plus, nous utilisons un groupe de contrôle basé sur des données appariées provenant du Panel Suisse de Ménage. Nos analyses montrent des résultats fortement contrastés. D'un côté, la majeure partie des travailleurs ont vécu une transition professionnelle plutôt facile : plus des deux tiers des personnes ont retrouvé un travail et parmi elles plus de la moitié en moins de six mois. Par rapport aux relations sociales, tant avec leur partenaire, qu'avec les membres de leur famille et leurs amis, les changements expérimentés étaient plus fréquemment positifs que négatifs. De l'autre côté, cependant, pour une petite partie de travailleurs la fermeture de leur entreprise a eu des conséquences très négatives sur leur carrière et leur bien-être. Au moment de notre enquête, presque vingt pourcents des travailleurs étaient au chômage. Les personnes au chômage et celles qui avaient quitté le marché du travail ont été particulièrement affectées par une diminution de leur bien-être subjectif. Les plus vulnérables parmi les travailleurs licenciés étaient ceux qui étaient âgés de plus de 55 ans. Notre analyse montre que les travailleurs âgés ont beaucoup moins fréquemment retrouvé un travail. Pour les personnes de plus de 55 ans qui ont tout de même retrouvé un emploi, la réinsertion a durée plus longtemps, les pertes de salaire étaient plus conséquentes et la diminution de la qualité de l'emploi plus grande que pour les autres cohortes. Au vu des changements démographiques actuels, ce résultat interpellant peut avoir des implications politiques importantes.

Closure of large wounds using rubber bands in rabbits

OBJECTIVE: to verify the effectiveness of the rubber elastic band in the treatment of large wounds of the body wall of rabbits by means of traction of its edges. METHODS: we studied 30 New Zealand rabbits, divided into three groups (n=10): Group 1- healing by secondary intention; Group 2- removal and eutopic repositioning of skin as full thickness skin graft; Group 3- Approximation of wound edges with elastic rubber band. In all animals, we removed a segment of the back skin and subcutaneous tissue down to the fascia, in accordance with an acrylic mold of 8cm long by 12cm wide. All animals were observed for 21 days. RESULTS: two animals of groups 1 and 2 had wound abscess. In Group 2, there was partial or total graft loss in 90% of animals. The complete closure of the wounds was observed in four animals of Group 1, six of Group 2 and eight of Group 3. There was no difference between the scar resistance values of groups 2 and 3, which were higher than those in Group 1. The scars of the three groups were characterized by the presence of mature connective tissue mixed with blood vessels and inflammatory infiltration, predominantly polymorphonuclear. CONCLUSION: the tensile strength of the wound edges with rubber elastic band is as efficient as the skin graft to treat rabbits' large body wounds.

Closure of the Monte Carlo dynamical equation in the spherical Sherrington-Kirkpatrick model

We study the analytical solution of the Monte Carlo dynamics in the spherical Sherrington-Kirkpatrick model using the technique of the generating function. Explicit solutions for one-time observables (like the energy) and two-time observables (like the correlation and response function) are obtained. We show that the crucial quantity which governs the dynamics is the acceptance rate. At zero temperature, an adiabatic approximation reveals that the relaxational behavior of the model corresponds to that of a single harmonic oscillator with an effective renormalized mass.

Infrared intensities of furan, pyrrole and thiophene: beyond the double harmonic approximation

Infrared intensities of the fundamental, overtone and combination transitions in furan, pyrrole and thiophene have been calculated using the variational normal coordinate code MULTIMODE. We use pure vibrational wavefunctions, and quartic force fields and cubic dipole moment vector surfaces, generated by density functional theory. The results are compared graphically with second-order perturbation calculations and with relative intensities from experiment for furan and pyrrole.

First order k-th moment finite element analysis of nonlinear operator equations with stochastic data

We develop and analyze a class of efficient Galerkin approximation methods for uncertainty quantification of nonlinear operator equations. The algorithms are based on sparse Galerkin discretizations of tensorized linearizations at nominal parameters. Specifically, we consider abstract, nonlinear, parametric operator equations J(\alpha ,u)=0 for random input \alpha (\omega ) with almost sure realizations in a neighborhood of a nominal input parameter \alpha _0. Under some structural assumptions on the parameter dependence, we prove existence and uniqueness of a random solution, u(\omega ) = S(\alpha (\omega )). We derive a multilinear, tensorized operator equation for the deterministic computation of k-th order statistical moments of the random solution's fluctuations u(\omega ) - S(\alpha _0). We introduce and analyse sparse tensor Galerkin discretization schemes for the efficient, deterministic computation of the k-th statistical moment equation. We prove a shift theorem for the k-point correlation equation in anisotropic smoothness scales and deduce that sparse tensor Galerkin discretizations of this equation converge in accuracy vs. complexity which equals, up to logarithmic terms, that of the Galerkin discretization of a single instance of the mean field problem. We illustrate the abstract theory for nonstationary diffusion problems in random domains.

Chebyshev-Laurent polynomials and weighted approximation

Let (a, b) subset of (0, infinity) and for any positive integer n, let S-n be the Chebyshev space in [a, b] defined by S-n:= span{x(-n/2+k),k= 0,...,n}. The unique (up to a constant factor) function tau(n) is an element of S-n, which satisfies the orthogonality relation S(a)(b)tau(n)(x)q(x) (x(b - x)(x - a))(-1/2) dx = 0 for any q is an element of Sn-1, is said to be the orthogonal Chebyshev S-n-polynomials. This paper is an attempt to exibit some interesting properties of the orthogonal Chebyshev S-n-polynomials and to demonstrate their importance to the problem of approximation by S-n-polynomials. A simple proof of a Jackson-type theorem is given and the Lagrange interpolation problem by functions from S-n is discussed. It is shown also that tau(n) obeys an extremal property in L-q, 1 less than or equal to q less than or equal to infinity. Natural analogues of some inequalities for algebraic polynomials, which we expect to hold for the S-n-pelynomials, are conjectured.

Neuroelectromagnetic correlates of perceptual closure processes

Perceptual closure refers to the coherent perception of an object under circumstances when the visual information is incomplete. Although the perceptual closure index observed in electroencephalography reflects that an object has been recognized, the full spatiotemporal dynamics of cortical source activity underlying perceptual closure processing remain unknown so far. To address this question, we recorded magnetoencephalographic activity in 15 subjects (11 females) during a visual closure task and performed beamforming over a sequence of successive short time windows to localize high-frequency gamma-band activity (60–100 Hz). Two-tone images of human faces (Mooney faces) were used to examine perceptual closure. Event-related fields exhibited a magnetic closure index between 250 and 325 ms. Time-frequency analyses revealed sustained high-frequency gamma-band activity associated with the processing of Mooney stimuli; closure-related gamma-band activity was observed between 200 and 300 ms over occipitotemporal channels. Time-resolved source reconstruction revealed an early (0–200 ms) coactivation of caudal inferior temporal gyrus (cITG) and regions in posterior parietal cortex (PPC). At the time of perceptual closure (200–400 ms), the activation in cITG extended to the fusiform gyrus, if a face was perceived. Our data provide the first electrophysiological evidence that perceptual closure for Mooney faces starts with an interaction between areas related to processing of three-dimensional structure from shading cues (cITG) and areas associated with the activation of long-term memory templates (PPC). Later, at the moment of perceptual closure, inferior temporal cortex areas specialized for the perceived object are activated, i.e., the fusiform gyrus related to face processing for Mooney stimuli.

Analytical Models of Exoplanetary Atmospheres. II. Radiative Transfer via the Two-Stream Approximation

We present a comprehensive analytical study of radiative transfer using the method of moments and include the effects of non-isotropic scattering in the coherent limit. Within this unified formalism, we derive the governing equations and solutions describing two-stream radiative transfer (which approximates the passage of radiation as a pair of outgoing and incoming fluxes), flux-limited diffusion (which describes radiative transfer in the deep interior) and solutions for the temperature-pressure profiles. Generally, the problem is mathematically under-determined unless a set of closures (Eddington coefficients) is specified. We demonstrate that the hemispheric (or hemi-isotropic) closure naturally derives from the radiative transfer equation if energy conservation is obeyed, while the Eddington closure produces spurious enhancements of both reflected light and thermal emission. We concoct recipes for implementing two-stream radiative transfer in stand-alone numerical calculations and general circulation models. We use our two-stream solutions to construct toy models of the runaway greenhouse effect. We present a new solution for temperature-pressure profiles with a non-constant optical opacity and elucidate the effects of non-isotropic scattering in the optical and infrared. We derive generalized expressions for the spherical and Bond albedos and the photon deposition depth. We demonstrate that the value of the optical depth corresponding to the photosphere is not always 2/3 (Milne's solution) and depends on a combination of stellar irradiation, internal heat and the properties of scattering both in optical and infrared. Finally, we derive generalized expressions for the total, net, outgoing and incoming fluxes in the convective regime.

Exact moment calculations for genetic models with migration, mutation, and drift

Using properties of moment stationarity we develop exact expressions for the mean and covariance of allele frequencies at a single locus for a set of populations subject to drift, mutation, and migration. Some general results can be obtained even for arbitrary mutation and migration matrices, for example: (1) Under quite general conditions, the mean vector depends only on mutation rates, not on migration rates or the number of populations. (2) Allele frequencies covary among all pairs of populations connected by migration. As a result, the drift, mutation, migration process is not ergodic when any finite number of populations is exchanging genes. in addition, we provide closed form expressions for the mean and covariance of allele frequencies in Wright's finite-island model of migration under several simple models of mutation, and we show that the correlation in allele frequencies among populations can be very large for realistic rates of mutation unless an enormous number of populations are exchanging genes. As a result, the traditional diffusion approximation provides a poor approximation of the stationary distribution of allele frequencies among populations. Finally, we discuss some implications of our results for measures of population structure based on Wright's F-statistics.

Image analysis by moment invariants using a set of step-like basis functions

Moment invariants have been thoroughly studied and repeatedly proposed as one of the most powerful tools for 2D shape identification. In this paper a set of such descriptors is proposed, being the basis functions discontinuous in a finite number of points. The goal of using discontinuous functions is to avoid the Gibbs phenomenon, and therefore to yield a better approximation capability for discontinuous signals, as images. Moreover, the proposed set of moments allows the definition of rotation invariants, being this the other main design concern. Translation and scale invariance are achieved by means of standard image normalization. Tests are conducted to evaluate the behavior of these descriptors in noisy environments, where images are corrupted with Gaussian noise up to different SNR values. Results are compared to those obtained using Zernike moments, showing that the proposed descriptor has the same performance in image retrieval tasks in noisy environments, but demanding much less computational power for every stage in the query chain.

Mesenchymal Stromal Cells From Adipose Tissue Attached To Suture Material Enhance The Closure Of Enterocutaneous Fistulas In A Rat Model.

Surgical treatment for enterocutaneous fistulas (EF) frequently fails. Cell therapy may represent a new approach to treatment. Mesenchymal stromal cells (MSCs) have high proliferative and differentiation capacity. This study aimed to investigate whether MSCs could adhere to suture filament (SF), promoting better EF healing. MSCs, 1 × 10(6), from adipose tissue (ATMSCs) were adhered to a Polyvicryl SF by adding a specific fibrin glue formulation. Adhesion was confirmed by confocal and scanning electron microscopy (SEM). A cecal fistula was created in 22 Wistar rats by incising the cecum and suturing the opening to the surgical wound subcutaneously with four separate stitches. The animals were randomly allocated to three groups: control (CG)-five animals, EF performed; injection (IG)-eight animals 1 × 10(6) ATMSCs injected around EF borders; and suture filament (SG): nine animals, sutured with 1 × 10(6) ATMSCs attached to the filaments with fibrin glue. Fistulas were photographed on the operation day and every 3 days until the 21st day and analyzed by two observers using ImageJ Software. Confocal and SEM results demonstrated ATMSCs adhered to SF (ATMSCs-SF). The average reduction size of the fistula area at 21st day was greater for the SG group (90.34%, P < 0.05) than the IG (71.80%) and CG (46.54%) groups. ATMSCs adhered to SF maintain viability and proliferative capacity. EF submitted to ATMSCs-SF procedure showed greater recovery and healing. This approach might be a new and effective tool for EF treatment.

Topiramate-associated acute, bilateral, angle-closure glaucoma: case report

This paper describes a topiramate induced acute bilateral angle-closure glaucoma. This rare adverse effect is an idiosyncratic reaction characterized by uveal effusion and lens forward displacement, leading to increased intraocular pressure and vision loss. We describe a 55 year-old white woman with migraine, spasmodic torticollis and essential tremor, who developed bilateral acute angle-closure glaucoma, one week after starting topiramate 25 mg/day. She was seen at the Ophthalmology Emergency Department of the Fundação João Penido Burnier (Campinas, SP, Brazil) with a 4 hours history of blurry vision, ocular pain and bright flashes vision. Slit lamp examination revealed moderate conjunctival injection and corneal edema, and shallow anterior chambers. Intraocular pressure was 48 mmHg in both eyes. Fundoscopic examination findings were normal. She was treated with timolol, brimonidine, dorzolamide, pilocarpine, prednisone acetate eye drops and acetazolamide. One hour after those measures, as the intraocular pressure was 30 mmHg, she received a manitol intravenous injection and the intraocular pressure normalized. After 24 hours an iridotomy with Yag laser was performed. Topiramate was discontinued and she was totally recovered after one week.