752 research outputs found
Direct Laser Sintering of Borosilicate Glass
Despite the advantages that selective laser sintering (SLS) offers in terms of material
availability, many materials have yet to be explored for feasibility and even fewer are
available on a commercial basis. This paper presents initial investigations for one such
material, borosilicate glass, which could be of particular interest to filter manufacturers
because it presents an attractive alternative to the conventional, time-consuming way of
producing filters of various porosity classes. Process results are presented including a
determination of the optimal parameter window and the effect of processing parameters on the
density and surface quality. The effects of thermal post-processing and the inclusion of an
additive are also discussed.Mechanical Engineerin
Direct Laser Sintering of Ceramics
For more than one decade layer manufacturing technologies assist the development of new
products. Due to a layer-wise build-up of a three-dimensional geometry, nearly every
complex design is producible in a short period of time. Selective Laser Sintering is a powderbased technique to produce plastic prototypes (Rapid Prototyping) or metal mould inserts
(Rapid Tooling). The laser sintering of ceramic powder is not yet commercialized but
applications could be both Rapid Prototyping and Rapid Tooling. The former involves the
laser sintering of investment casting shells and cores to cast metal prototypes and the latter the
laser sintering of ceramic master patterns for metal spray forming of steel mould inserts. The
advantage compared to actual processes are a faster availability of the final product. To
facilitate these applications, special ceramic powders as well as new process parameter
combinations were investigated. This paper will present achieved results within the abovedescribed applications.Mechanical Engineerin
Induced Polyakov supergravity on Riemann surfaces of higher genus
An effective action is obtained for the , induced supergravity on a
compact super Riemann surface (without boundary) of genus ,
as the general solution of the corresponding superconformal Ward identity. This
is accomplished by defining a new super integration theory on
which includes a new formulation of the super Stokes theorem and residue
calculus in the superfield formalism. Another crucial ingredient is the notion
of polydromic fields. The resulting action is shown to be well-defined and free
of singularities on \sig. As a by-product, we point out a morphism between
the diffeomorphism symmetry and holomorphic properties.Comment: LPTB 93-10, Latex file 20 page
On the holomorphic factorization for superconformal fields
For a generic value of the central charge, we prove the holomorphic
factorization of partition functions for free superconformal fields which are
defined on a compact Riemann surface without boundary. The partition functions
are viewed as functionals of the Beltrami coefficients and their fermionic
partners which variables parametrize superconformal classes of metrics.Comment: 5 pages, LATEX, MPI-Ph/92-7
The Polyakov action on the supertorus
A consistent method for obtaining a well-defined Polyakov action on the
supertorus is presented. This method uses the covariantization of derivative
operators and enables us to construct a Polyakov action which is globally
defined.Comment: 15 pages LaTe
Determinants of methicillin-susceptible Staphylococcus aureus native bone and joint infection treatment failure: a retrospective cohort study.
BACKGROUND: Although methicillin-susceptible Staphylococcus aureus (MSSA) native bone and joint infection (BJI) constitutes the more frequent clinical entity of BJI, prognostic studies mostly focused on methicillin-resistant S. aureus prosthetic joint infection. We aimed to assess the determinants of native MSSA BJI outcomes.
METHODS: Retrospective cohort study (2001-2011) of patients admitted in a reference hospital centre for native MSSA BJI. Treatment failure determinants were assessed using Kaplan-Meier curves and binary logistic regression.
RESULTS: Sixty-six patients (42 males [63.6%]; median age 61.2Â years; interquartile range [IQR] 45.9-71.9) presented an acute (nâ=â38; 57.6%) or chronic (nâ=â28; 42.4%) native MSSA arthritis (nâ=â15; 22.7%), osteomyelitis (nâ=â19; 28.8%) or spondylodiscitis (nâ=â32; 48.5%), considered as "difficult-to-treat" in 61 cases (92.4%). All received a prolonged (27.1Â weeks; IQR, 16.9-36.1) combined antimicrobial therapy, after surgical management in 37 cases (56.1%). Sixteen treatment failures (24.2%) were observed during a median follow-up period of 63.3Â weeks (IQR, 44.7-103.1), including 13 persisting infections, 1 relapse after treatment disruption, and 2 super-infections. Independent determinants of treatment failure were the existence of a sinus tract (odds ratio [OR], 5.300; 95% confidence interval [CI], 1.166-24.103) and a prolonged delay to infectious disease specialist referral (OR, 1.134; 95% CI 1.013-1.271).
CONCLUSIONS: The important treatment failure rate pinpointed the difficulty of cure encountered in complicated native MSSA BJI. An early infectious disease specialist referral is essential, especially in debilitated patients or in presence of sinus tract
d=2, N=2 Superconformal Symmetries and Models
We discuss the following aspects of two-dimensional N=2 supersymmetric
theories defined on compact super Riemann surfaces: parametrization of (2,0)
and (2,2) superconformal structures in terms of Beltrami coefficients and
formulation of superconformal models on such surfaces (invariant actions,
anomalies and compensating actions, Ward identities).Comment: 43 pages, late
W-algebras from symplectomorphisms
It is shown how -algebras emerge from very peculiar canonical
transformations with respect to the canonical symplectic structure on a compact
Riemann surface. The action of smooth diffeomorphisms of the cotangent bundle
on suitable generating functions is written in the BRS framework while a
-symmetry is exhibited. Subsequently, the complex structure of the symmetry
spaces is studied and the related BRS properties are discussed. The specific
example of the so-called -algebra is treated in relation to some other
different approaches.Comment: LaTex, 25 pages, no figures, to appear in Journ. Math. Phy
Invasive pulmonary aspergillosis in chronic obstructive pulmonary disease: an emerging fungal pathogen
ABSTRACTAcute invasive pulmonary aspergillosis occurs predominantly in immunocompromised hosts, with increasing numbers of cases of invasive aspergillosis among patients with chronic obstructive pulmonary disease (COPD) being reported. Among 13 cases of invasive aspergillosis diagnosed in COPD patients admitted to the intensive care unit with acute respiratory distress, the only risk factor for invasive fungal infection was corticosteroid treatment. Invasive aspergillosis should be suspected in COPD patients receiving steroid treatment who have extensive pulmonary infiltrates. Survival depends on rapid diagnosis and early appropriate treatment. A decrease or interruption of steroid treatment should be considered as part of the overall therapeutic strategy
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