151 research outputs found

    Configuration spaces are not homotopy invariant

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    We present a counterexample to the conjecture on the homotopy invariance of configuration spaces. More precisely, we consider the lens spaces L7,1L_{7,1} and L7,2L_{7,2}, and prove that their configuration spaces are not homotopy equivalent by showing that their universal coverings have different Massey products.Comment: 6 page

    Algebraic structures on graph cohomology

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    We define algebraic structures on graph cohomology and prove that they correspond to algebraic structures on the cohomology of the spaces of imbeddings of S^1 or R into R^n. As a corollary, we deduce the existence of an infinite number of nontrivial cohomology classes in Imb(S^1,R^n) when n is even and greater than 3. Finally, we give a new interpretation of the anomaly term for the Vassiliev invariants in R^3.Comment: Typos corrected, exposition improved. 14 pages, 2 figures. To appear in J. Knot Theory Ramification

    Powertrain Modal Analysis for Defining the Requirements for a Vehicle Drivability Study

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    The powertrain of a car plays a major role in establishing the vehicle’s offered comfort due to vibrations because it is the heaviest single component installed on the chassis; therefore, when oscillating, it transmits considerable forces to the chassis, inducing unwanted vibrations. For this reason, it is important to identify some associated properties with the powertrain suspension system that describe the performance of its rigid body dynamics. In this way, we could place constraints and requirements on these quantities in order to exclude all the configurations that cause intolerable levels of vibrations, and include all the others in the analysis for further evaluation. The definition of these requirements is critical: a poor setting of requirements excludes potentially good powertrain suspension setups and includes those ones with a drivability index that is too poor. In this paper, we identify a set of quantities that show correlation with the vibration performance of the powertrain setup. A method for testing the specificity of the requirements is also shown in order to evaluate which requirements perform best when it comes to filtering engine suspension setups that provide an acceptable level of vibrations

    Graft monocytic myeloid-derived suppressor cell content predicts the risk of acute graft-versus-host disease after allogeneic transplantation of granulocyte colony-stimulating factor-mobilized peripheral blood stem cells.

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    Abstract Myeloid-derived suppressor cells (MDSCs) are powerful immunomodulatory cells that in mice play a role in infectious and inflammatory disorders, including acute graft-versus-host disease (GVHD) after allogeneic hematopoietic stem cell transplantation. Their relevance in clinical acute GVHD is poorly known. We analyzed whether granulocyte colony-stimulating factor (G-CSF) administration, used to mobilize hematopoietic stem cells, affected the frequency of MDSCs in the peripheral blood stem cell grafts of 60 unrelated donors. In addition, we evaluated whether the MDSC content in the peripheral blood stem cell grafts affected the occurrence of acute GVHD in patients undergoing unrelated donor allogeneic stem cell transplantation. Systemic treatment with G-CSF induces an expansion of myeloid cells displaying the phenotype of monocytic MDSCs (Lin low/neg HLA-DR − CD11b + CD33 + CD14 + ) with the ability to suppress alloreactive T cells in vitro, therefore meeting the definition of MDSCs. Monocytic MDSC dose was the only graft parameter to predict acute GVHD. The cumulative incidence of acute GVHD at 180 days after transplantation for recipients receiving monocytic MDSC doses below and above the median was 63% and 22%, respectively ( P = .02). The number of monocytic MDSCs infused did not impact the relapse rate or the transplant-related mortality rate ( P > .05). Although further prospective studies involving larger sample size are needed to validate the exact monocytic MDSC graft dose that protects from acute GVHD, our results strongly suggest the modulation of G-CSF might be used to affect monocytic MDSCs graft cell doses for prevention of acute GVHD

    Configuration spaces and Vassiliev classes in any dimension

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    The real cohomology of the space of imbeddings of S^1 into R^n, n>3, is studied by using configuration space integrals. Nontrivial classes are explicitly constructed. As a by-product, we prove the nontriviality of certain cycles of imbeddings obtained by blowing up transversal double points in immersions. These cohomology classes generalize in a nontrivial way the Vassiliev knot invariants. Other nontrivial classes are constructed by considering the restriction of classes defined on the corresponding spaces of immersions.Comment: Published by Algebraic and Geometric Topology at http://www.maths.warwick.ac.uk/agt/AGTVol2/agt-2-39.abs.htm

    Evaluation of White Striping prevalence and predisposing factors in broilers at slaughter

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    White striping ( WS: ) is an alteration of breast and thigh muscles of broiler chickens characterized by the presence of white striations parallel to the direction of muscle fibers. This study was performed to evaluate the prevalence and the predisposing factors to WS in commercial broilers of different weight reared in northern Italy. Fifty seven broiler flocks, including animals of medium- and heavy-weight, were grossly evaluated at slaughter for the presence of WS. For each flock, breeding data (mean BW at slaughter, ADG, sex, color of skin and fat, genetic line, age, antibiotic treatment, and prevalence of deep pectoral myopathy) were collected and statistically analyzed to assess their correlation with WS. Histology of breast fillets affected by different grades of WS was performed to evaluate potential differences between medium- and heavy-weight broilers. The overall prevalence of WS in medium- and heavy-weight broilers (mean BW 2.59 \ub1 0.13 kg and 3.64 \ub1 0.34 kg, respectively) was 70.2 \ub1 7.9% and 82.51 \ub1 8.5%, respectively, while the percentage of severe WS was 13.3 \ub1 7.1% and 25.7 \ub1 12.8%, respectively. A strong correlation was found between presence of WS, BW at slaughter, and ADG (Pearson correlation = 0.69, P < 0.01; Pearson correlation = 0.67, P < 0.01). WS also closely correlated with the prevalence of deep pectoral myopathy (Spearman's Rho slaughterhouse 1 = 0.74, Spearman's Rho slaughterhouse 2 = 0.51, P < 0.01). No correlation was found between genetics or sanitary status of the flock and WS. Histology confirmed that breasts with WS lesions were affected by a polyphasic degenerative and necrotizing myopathy, and that the lesions, as expected, were more severe in heavy-weight broilers. In conclusion, WS is a major concern in commercial meat poultry reared in Italy, affecting more severely heavier broilers, and it is mainly related to the BW and ADG of animals

    Atypical antipsychotics and metabolic syndrome : from molecular mechanisms to clinical differences

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    Atypical antipsychotics (AAPs) are commonly prescribed medications to treat schizophre-nia, bipolar disorders and other psychotic disorders. However, they might cause metabolic syndrome (MetS) in terms of weight gain, dyslipidemia, type 2 diabetes (T2D), and high blood pressure, which are responsible for reduced life expectancy and poor adherence. Importantly, there is clear evidence that early metabolic disturbances can precede weight gain, even if the latter still remains the hallmark of AAPs use. In fact, AAPs interfere profoundly with glucose and lipid homeostasis acting mostly on hypothalamus, liver, pancreatic β-cells, adipose tissue, and skeletal muscle. Their ac-tions on hypothalamic centers via dopamine, serotonin, acetylcholine, and histamine receptors affect neuropeptides and 5′ AMP-activated protein kinase (AMPK) activity, thus producing a supra-physiological sympathetic outflow augmenting levels of glucagon and hepatic glucose production. In addition, altered insulin secretion, dyslipidemia, fat deposition in the liver and adipose tissues, and insulin resistance become aggravating factors for MetS. In clinical practice, among AAPs, olan-zapine and clozapine are associated with the highest risk of MetS, whereas quetiapine, risperidone, asenapine and amisulpride cause moderate alterations. The new AAPs such as ziprasidone, lurasi-done and the partial agonist aripiprazole seem more tolerable on the metabolic profile. However, these aspects must be considered together with the differences among AAPs in terms of their efficacy, where clozapine still remains the most effective. Intriguingly, there seems to be a correlation between AAP’s higher clinical efficacy and increase risk of metabolic alterations. Finally, a multidisciplinary approach combining psychoeducation and therapeutic drug monitoring (TDM) is proposed as a first-line strategy to avoid the MetS. In addition, pharmacological treatments are discussed as well.Publisher PDFPeer reviewe
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