Open surgical procedures for incisional hernias

BACKGROUND: Incisional hernias occur frequently after abdominal surgery and can cause serious complications. The choice of a type of open operative repair is controversial. Determining the type of open operative repair is controversial, as the recurrence rate may be as high as 54%. OBJECTIVES: To identify the best available open operative techniques for incisional hernias. SEARCH STRATEGY: Electronic databases MEDLINE, EMBASE, LILACS, and the Cochrane Central Register of Controlled Trials (CENTRAL) were searched from 1990 to 2007 and trials were identified from the known trial reference lists. SELECTION CRITERIA: Studies were eligible for inclusion if they were randomized trials comparing different techniques for open operative techniques for incisional hernias. DATA COLLECTION AND ANALYSIS: Statistical analyses were performed using the fixed effects model. Results were expressed as relative risk for dichotomous outcomes and weighted mean difference for continuous outcomes with 95% confidence intervals. MAIN RESULTS: Eight trials comparing different open repairs for incisional hernias were identified; one trial was excluded. The included studies enrolled 1,141 patients. The results of three trials comparing suture repair versus mesh repair were pooled. Hernia recurrence was more frequent, wound infection less frequent in the direct suture group compared to the onlay or sublay mesh groups. The recurrence rates of two trials comparing onlay and sublay positions were pooled. This comparison yielded no difference in recurrences (two studies pooled), although operation time was shorter in the onlay group (one study). No difference was found in recurrence, satisfaction with cosmetics, or infection between the onlay standard mesh and skin autograft groups, following analysis pooling the two treatment arms. However, the analysis demonstrated less pain in the skin autograft group. Other trials comparing different mesh materials or different positions of the mesh, or comparing mesh with the components separation technique are described individually. The comparison between lightweight and standard mesh showed a trend for more recurrences in the lightweight group. The comparison between onlay and intraperitoneal mesh positions resulted in non significant fewer hernia recurrences, less seroma formation and more postoperative pain in the intraperitoneal group. No differences in the recurrence rates between the components separation and the intraperitoneal mesh technique. AUTHORS' CONCLUSIONS: There is good evidence from three trials that open mesh repair is superior to suture repair in terms of recurrences, but inferior when considering wound infection. Six trials yielded insufficient evidence as to which type of mesh or which mesh position (on- or sublay) should be used. There was also insufficient evidence to advocate the use of the components separation technique

Eenvoudige elleboogluxaties in Nederland: Wat doen Nederlandse chirurgen?

Abstract: Er is weinig evidence voor de optimale behandeling van eenvoudige elleboogluxaties. Hoewel er aanwijzingen zijn dat eenvoudige elleboogluxaties niet te lang moeten worden geïmmobiliseerd en functioneel kunnen worden nabehandeld. Om een overzicht te krijgen over hoe eenvoudige elleboogluxaties in Nederland worden behandeld, verrichtten wij een enquête onder leden van de Nederlandse Vereniging van Traumatologie. Alle leden ontvingen een e-mail met het verzoek om een digitale vragenlijst over de behandeling van elleboogluxaties in te vullen. Het response percentage was 17% (n=90). Vijfendertig (39%) chirurgen verbinden geen consequenties aan stabiliteitsonderzoek van de elleboog na repositie. Drieënzestig procent van deze chirurgen behandelt de patiënten met een gipsverband gedurende gemiddeld 3.4 weken. Bij 55 (61%) van de 90 respondenten beïnvloed het stabiliteitsonderzoek wel de vorm van behandeling. Bij een stabiel gewricht wordt in ongeveer 64% van de gevallen een functionele behandeling voorgeschreven en bij een instabiel gewricht behandelen 24% van de respondenten functioneel met een functionele fixateur. De resultaten van de enquête onder Nederlandse chirurgen laat zien, dat de meeste ondervraagden immobilisatie verkiezen boven functionele behandelingAbstract Background: Randomised controlled trials and observational comparative studies show little proof for the optimal form of treatment for simple elbow dislocations. However, there is some evidence that functional treatment in simple elbow dislocations may lead to better functional outcome. To get an overview of how simple elbow dislocations are treated in the Netherlands we performed a survey among Dutch surgeons. Methods: All members of the Dutch Society of Traumatology received an e-mail with the request to fill out an electronic questionnaire. Results: The response rate was 17% (n=90) . Thirty vive (39%) of them stated that stability testing after reposition of the joint did not influence subsequent form of treatment. Sixty three percent of them treated patients with a above the elbow cast for a mean of 3.4 weeks. Fifty five (61%) responders used stability testing as a guide for treatment. joint is stable after reposition. In the case of a stabile joint 64% of these surgeons treat patients with functional treatment. When there is joint instability 24% prefer functional treatment with a hinged external fixator. Conclusion: The results of this inquiry among Dutch surgeons showed that the majority of simple elbow dislocations are treated with immobilisation and that functional treatment is not widespread

Composite magnetostrictive materials for advanced automotive magnetomechanical sensors

In this paper we present the development of a composite magnetostrictive material for automotive applications. The material is based on cobalt ferrite, CoO×Fe₂O₃, and contains a small fraction of metallic matrix phase that serves both as a liquid phase sintering aid during processing and enhances the mechanical properties over those of a simple sintered ferrite ceramic. In addition the metal matrix makes it possible to braze the material making the assembly of a sensor relatively simple. The material exhibits good sensitivity and should have high corrosion resistance while at the same time it is low cost

A New Recursion Relation for the 6j-Symbol

The 6j-symbol is a fundamental object from the re-coupling theory of SU(2) representations. In the limit of large angular momenta, its asymptotics is known to be described by the geometry of a tetrahedron with quantized lengths. This article presents a new recursion formula for the square of the 6j-symbol. In the asymptotic regime, the new recursion is shown to characterize the closure of the relevant tetrahedron. Since the 6j-symbol is the basic building block of the Ponzano-Regge model for pure three-dimensional quantum gravity, we also discuss how to generalize the method to derive more general recursion relations on the full amplitudes.Comment: 10 pages, v2: title and introduction changed, paper re-structured; Annales Henri Poincare (2011

On the fourth-order accurate compact ADI scheme for solving the unsteady Nonlinear Coupled Burgers' Equations

The two-dimensional unsteady coupled Burgers' equations with moderate to severe gradients, are solved numerically using higher-order accurate finite difference schemes; namely the fourth-order accurate compact ADI scheme, and the fourth-order accurate Du Fort Frankel scheme. The question of numerical stability and convergence are presented. Comparisons are made between the present schemes in terms of accuracy and computational efficiency for solving problems with severe internal and boundary gradients. The present study shows that the fourth-order compact ADI scheme is stable and efficient

Living for the weekend: youth identities in northeast England

Consumption and consumerism are now accepted as key contexts for the construction of youth identities in de-industrialized Britain. This article uses empirical evidence from interviews with young people to suggest that claims of `new community' are overstated, traditional forms of friendship are receding, and increasingly atomized and instrumental youth identities are now being culturally constituted and reproduced by the pressures and anxieties created by enforced adaptation to consumer capitalism. Analysis of the data opens up the possibility of a critical rather than a celebratory exploration of the wider theoretical implications of this process

Particle interactions with single or multiple 3D solar reconnecting current sheets

The acceleration of charged particles (electrons and protons) in flaring solar active regions is analyzed by numerical experiments. The acceleration is modelled as a stochastic process taking place by the interaction of the particles with local magnetic reconnection sites via multiple steps. Two types of local reconnecting topologies are studied: the Harris-type and the X-point. A formula for the maximum kinetic energy gain in a Harris-type current sheet, found in a previous work of ours, fits well the numerical data for a single step of the process. A generalization is then given approximating the kinetic energy gain through an X-point. In the case of the multiple step process, in both topologies the particles' kinetic energy distribution is found to acquire a practically invariant form after a small number of steps. This tendency is interpreted theoretically. Other characteristics of the acceleration process are given, such as the mean acceleration time and the pitch angle distributions of the particles.Comment: 18 pages, 9 figures, Solar Physics, in pres

Dust Devil Tracks

Dust devils that leave dark- or light-toned tracks are common on Mars and they can also be found on the Earth’s surface. Dust devil tracks (hereinafter DDTs) are ephemeral surface features with mostly sub-annual lifetimes. Regarding their size, DDT widths can range between ∼1 m and ∼1 km, depending on the diameter of dust devil that created the track, and DDT lengths range from a few tens of meters to several kilometers, limited by the duration and horizontal ground speed of dust devils. DDTs can be classified into three main types based on their morphology and albedo in contrast to their surroundings; all are found on both planets: (a) dark continuous DDTs, (b) dark cycloidal DDTs, and (c) bright DDTs. Dark continuous DDTs are the most common type on Mars. They are characterized by their relatively homogenous and continuous low albedo surface tracks. Based on terrestrial and martian in situ studies, these DDTs most likely form when surficial dust layers are removed to expose larger-grained substrate material (coarse sands of ≥500 μm in diameter). The exposure of larger-grained materials changes the photometric properties of the surface; hence leading to lower albedo tracks because grain size is photometrically inversely proportional to the surface reflectance. However, although not observed so far, compositional differences (i.e., color differences) might also lead to albedo contrasts when dust is removed to expose substrate materials with mineralogical differences. For dark continuous DDTs, albedo drop measurements are around 2.5 % in the wavelength range of 550–850 nm on Mars and around 0.5 % in the wavelength range from 300–1100 nm on Earth. The removal of an equivalent layer thickness around 1 μm is sufficient for the formation of visible dark continuous DDTs on Mars and Earth. The next type of DDTs, dark cycloidal DDTs, are characterized by their low albedo pattern of overlapping scallops. Terrestrial in situ studies imply that they are formed when sand-sized material that is eroded from the outer vortex area of a dust devil is redeposited in annular patterns in the central vortex region. This type of DDT can also be found in on Mars in orbital image data, and although in situ studies are lacking, terrestrial analog studies, laboratory work, and numerical modeling suggest they have the same formation mechanism as those on Earth. Finally, bright DDTs are characterized by their continuous track pattern and high albedo compared to their undisturbed surroundings. They are found on both planets, but to date they have only been analyzed in situ on Earth. Here, the destruction of aggregates of dust, silt and sand by dust devils leads to smooth surfaces in contrast to the undisturbed rough surfaces surrounding the track. The resulting change in photometric properties occurs because the smoother surfaces have a higher reflectance compared to the surrounding rough surface, leading to bright DDTs. On Mars, the destruction of surficial dust-aggregates may also lead to bright DDTs. However, higher reflective surfaces may be produced by other formation mechanisms, such as dust compaction by passing dust devils, as this may also cause changes in photometric properties. On Mars, DDTs in general are found at all elevations and on a global scale, except on the permanent polar caps. DDT maximum areal densities occur during spring and summer in both hemispheres produced by an increase in dust devil activity caused by maximum insolation. Regionally, dust devil densities vary spatially likely controlled by changes in dust cover thicknesses and substrate materials. This variability makes it difficult to infer dust devil activity from DDT frequencies. Furthermore, only a fraction of dust devils leave tracks. However, DDTs can be used as proxies for dust devil lifetimes and wind directions and speeds, and they can also be used to predict lander or rover solar panel clearing events. Overall, the high DDT frequency in many areas on Mars leads to drastic albedo changes that affect large-scale weather patterns

Electron Scattering From High-Momentum Neutrons in Deuterium

We report results from an experiment measuring the semi-inclusive reaction $d(e,e'p_s)$ where the proton $p_s$ is moving at a large angle relative to the momentum transfer. If we assume that the proton was a spectator to the reaction taking place on the neutron in deuterium, the initial state of that neutron can be inferred. This method, known as spectator tagging, can be used to study electron scattering from high-momentum (off-shell) neutrons in deuterium. The data were taken with a 5.765 GeV electron beam on a deuterium target in Jefferson Laboratory's Hall B, using the CLAS detector. A reduced cross section was extracted for different values of final-state missing mass $W^{*}$, backward proton momentum $\vec{p}_{s}$ and momentum transfer $Q^{2}$. The data are compared to a simple PWIA spectator model. A strong enhancement in the data observed at transverse kinematics is not reproduced by the PWIA model. This enhancement can likely be associated with the contribution of final state interactions (FSI) that were not incorporated into the model. A ``bound neutron structure function'' $F_{2n}^{eff}$ was extracted as a function of $W^{*}$ and the scaling variable $x^{*}$ at extreme backward kinematics, where effects of FSI appear to be smaller. For $p_{s}>400$ MeV/c, where the neutron is far off-shell, the model overestimates the value of $F_{2n}^{eff}$ in the region of $x^{*}$ between 0.25 and 0.6. A modification of the bound neutron structure function is one of possible effects that can cause the observed deviation.Comment: 33 pages RevTeX, 9 figures, to be submitted to Phys. Rev. C. Fixed 1 Referenc