100 research outputs found
Manipulating Managed Execution Runtimes to Support Self-Healing Systems
Self-healing systems require that repair mechanisms are available to resolve problems that arise while the system executes. Managed execution environments such as the Common Language Runtime (CLR) and Java Virtual Machine (JVM) provide a number of application services (application isolation, security sandboxing, garbage collection and structured exception handling) which are geared primarily at making managed applications more robust. However, none of these services directly enables applications to perform repairs or consistency checks of their components. From a design and implementation standpoint, the preferred way to enable repair in a self-healing system is to use an externalized repair/adaptation architecture rather than hardwiring adaptation logic inside the system where it is harder to analyze, reuse and extend. We present a framework that allows a repair engine to dynamically attach and detach to/from a managed application while it executes essentially adding repair mechanisms as another application service provided in the execution environment
A Structural Model for Octagonal Quasicrystals Derived from Octagonal Symmetry Elements Arising in -Mn Crystallization of a Simple Monatomic Liquid
While performing molecular dynamics simulations of a simple monatomic liquid,
we observed the crystallization of a material displaying octagonal symmetry in
its simulated diffraction pattern. Inspection of the atomic arrangements in the
crystallization product reveals large grains of the beta-Mn structure aligned
along a common 4-fold axis, with 45 degree rotations between neighboring
grains. These 45 degree rotations can be traced to the intercession of a second
crystalline structure fused epitaxially to the beta-Mn domain surfaces, whose
primitive cell has lattice parameters a = b = c = a_{beta-Mn}, alpha = beta =
90 degrees, and gamma = 45 degrees. This secondary phase adopts a structure
which appears to have no known counterpart in the experimental literature, but
can be simply derived from the Cr_3Si and Al_3Zr_4 structure types. We used
these observations as the basis for an atomistic structural model for octagonal
quasicrystals, in which the beta-Mn and the secondary phase structure unit
cells serve as square and rhombic tiles (in projection), respectively. Its
diffraction pattern down the octagonal axis resembles those experimentally
measured. The model is unique in being consistent with high-resolution electron
microscopy images showing square and rhombic units with edge-lengths equal to
that of the beta-Mn unit cell. Energy minimization of this configuration, using
the same pair potential as above, results in an alternative octagonal
quasiperiodic structure with the same tiling but a different atomic decoration
and diffraction pattern.Comment: 25 pages, 10 figure
Reduced diversity and increased virulence-gene carriage in intestinal enterobacteria of coeliac children
<p>Abstract</p> <p>Background</p> <p>Coeliac disease is an immune-mediated enteropathology triggered by the ingestion of cereal gluten proteins. This disorder is associated with imbalances in the composition of the gut microbiota that could be involved in its pathogenesis. The aim of the present study was to determine whether intestinal <it>Enterobacteriaceae </it>populations of active and non-active coeliac patients and healthy children differ in diversity and virulence-gene carriage, so as to establish a possible link between the pathogenic potential of enterobacteria and the disease.</p> <p>Methods</p> <p><it>Enterobacteriaceae </it>clones were isolated on VRBD agar from faecal samples of 31 subjects (10 active coeliac patients, 10 symptom-free coeliac patients and 11 healthy controls) and identified at species level by the API 20E system. <it>Escherichia coli </it>clones were classified into four phylogenetic groups A, B1, B2 and D and the prevalence of eight virulence-associated genes (type-1 fimbriae [<it>fimA</it>], P fimbriae [<it>papC</it>], S fimbriae [<it>sfaD/E</it>], Dr haemagglutinin [<it>draA</it>], haemolysin [<it>hlyA</it>], capsule K1 [<it>neuB</it>], capsule K5 [<it>KfiC</it>] and aerobactin [<it>iutA</it>]) was determined by multiplex PCR.</p> <p>Results</p> <p>A total of 155 <it>Enterobacteriaceae </it>clones were isolated. Non-<it>E. coli </it>clones were more commonly isolated in healthy children than in coeliac patients. The four phylogenetic <it>E. coli </it>groups were equally distributed in healthy children, while in both coeliac patients most commensal isolates belonged to group A. Within the virulent groups, B2 was the most prevalent in active coeliac disease children, while D was the most prevalent in non-active coeliac patients. <it>E coli </it>clones of the virulent phylogenetic groups (B2+D) from active and non-active coeliac patients carried a higher number of virulence genes than those from healthy individuals. Prevalence of P fimbriae (<it>papC</it>), capsule K5 (<it>sfaD/E</it>) and haemolysin (<it>hlyA</it>) genes was higher in <it>E. coli </it>isolated from active and non-active coeliac children than in those from control subjects.</p> <p>Conclusion</p> <p>This study has demonstrated that virulence features of the enteric microbiota are linked to coeliac disease.</p
Antibiotic resistance is linked to carriage of papC and iutA virulence genes and phylogenetic group D background in commensal and uropathogenic Escherichia coli from infants and young children
LaSeTe<sub>2</sub>-Temperature Dependent Structure Investigation and Electron Holography on a Charge-Denstiy-Wave-Hosting Compound
Single crystals of LaSeTe2 have been prepared by reaction of the elements in a LiCl/RbCl flux at 970 K for seven days. Satellite reflections observed in diffraction experiments indicate the presence of an incommensurate lattice distortion, which is of the charge-density-wave (CDW) type. The modulated structure has been solved from X-ray data at 173, 293, and 373 K. LaSeTe2 crystallizes in the 3+1-dimensional orthorhombic superspace group Cmcm(00γ)s00 (No. 63.2) with lattice parameters of a = 4.295(1), b = 25.371(4), c = 4.306(1) Å (173K), a = 4.297(1), b = 25.408(4), c = 4.309(1) Å (293 K), and a = 4.309(1), b = 25.481(6), c = 4,321(1) Å (373 K). The modulation vector q = (0, 0, 0.288) does not change over the temperature interval. Electron holographic investigations confirm the existence of the modulation and help to visualize the charge-density wave
Spontaneous Interferon Production and Epstein-Barr Virus Antigen Expression in Human Lymphoid Cell Lines
Igm-induced tumor cell cytotoxicity mediated by normal thymocytes.
Adult murine hosts undergoing induction and regression of primary Moloney sarcoma virus (MSV) tumors develop antibodies (1-3) and lymphocytes (4-6) which have activity in vitro against Moloney leukemia virus (MLV)-determined cell surface antigens on the tumor target cells (7). Antibodies which are able to lyse the appropriate virus-induced tumor target cells in the presence of complement appear in two peaks with respect to time after MSV injection (1). The first peak occurs in the early tumor-bearing animals 10-15 days after MSV (1). This is followed by a drop in the antibody titers in early regressors whereafter the antibodies rise and maintain high titers in long-term regressor animals (1, 8). The early as well as the late peaks contained cytotoxic activity in both the IgG and IgM fractions (1). Such MLC-specific antibodies are also active in the induction of tumor cell destruction in vitro by normal lymphoid cells (8). We have recently reported that both IgG and IgM were able to induce cytotoxicity by nonimmune spleen cells as well as potentiate the cytotoxic activity of immune spleen cells (9). We now report that IgM from MSV regressor mice will induce cytotoxicity against the tumor target cells not only by normal spleen cells but by normal thymocytes and the thymus cell cytotoxicity in combination with IgM appears to be more efficient than that produced with spleen cells
Characteristics of Antibiotic-Resistant Escherichia Coli In the Rectum of Healthy School-Children
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