209 research outputs found

    On the canonical divisor of smooth toroidal compactifications

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    In this paper, we show that the canonical divisor of a smooth toroidal compactification of a complex hyperbolic manifold must be nef if the dimension is greater or equal to three. Moreover, if n3n\geq 3 we show that the numerical dimension of the canonical divisor of a smooth nn-dimensional compactification is always bigger or equal to n1n-1. We also show that up to a finite \'etale cover all such compactifications have ample canonical class, therefore refining a classical theorem of Mumford and Tai. Finally, we improve in all dimensions n3n\geq 3 the cusp count for finite volume complex hyperbolic manifolds given in [DD15a].Comment: Title shortened to match published versio

    Exceptional collections and the bicanonical map of Keum's fake projective planes

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    On Seshadri constants of varieties with large fundamental group

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    Let XX be a smooth variety and let LL be an ample line bundle on XX. If π1alg(X)\pi^{alg}_{1}(X) is large, we show that the Seshadri constant ϵ(pL)\epsilon(p^{*}L) can be made arbitrarily large by passing to a finite \'etale cover p:XXp:X'\rightarrow X. This result answers affirmatively a conjecture of J.-M. Hwang. Moreover, we prove an analogous result when π1(X)\pi_{1}(X) is large and residually finite. Finally, under the same topological assumptions, we appropriately generalize these results to the case of big and nef line bundles. More precisely, given a big and nef line bundle LL on XX and a positive number N>0N>0, we show that there exists a finite \'etale cover p:XXp: X'\rightarrow X such that the Seshadri constant ϵ(pL;x)N\epsilon(p^{*}L; x)\geq N for any xpB+(L)=B+(pL)x\notin p^{*}\textbf{B}_{+}(L)=\textbf{B}_{+}(p^{*}L), where B+(L)\textbf{B}_{+}(L) is the augmented base locus of LL

    Moving Seshadri constants, and coverings of varieties of maximal Albanese dimension

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    Let XX be a smooth projective complex variety of maximal Albanese dimension, and let LXL \to X be a big line bundle. We prove that the moving Seshadri constants of the pull-backs of LL to suitable finite abelian \'etale covers of XX are arbitrarily large. As an application, given any integer k1k\geq 1, there exists an abelian \'etale cover p ⁣:XXp\colon X' \to X such that the adjoint system KX+pL\big|K_{X'} + p^*L \big| separates kk-jets away from the augmented base locus of pLp^*L, and the exceptional locus of the pull-back of the Albanese map of XX under pp

    Effect of chicken bone extracts on metabolic and mitochondrial functions of K562 cell line

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    Background: Tetracyclines’ use in intensive animal farming has raised some concerns regarding the biosafety for humans. Increasing evidences have revealed the presence of these drugs in processed animal by-products, such as bone, throughout the food chain. A potential off-target of tetracyclines is the bacterial-like mitochondrial translational machinery, thereby causing proteostatic alterations in mitochondrial DNA-encoded components of the oxidative phosphorylation system. Methods: The Seahorse methodology, confocal microscopy imaging of mitochondrial potential and reactive oxygen species, and q-RT-PCR analysis of the expression of genes involved in mitochondrial biogenesis and mitophagy were carried out on human lymphoblast derived K562 cell line challenged with bone powder derived from chicken treated with or without oxytetracycline and pure oxytetracycline. Results: A complex dose-dependent profile was attained with a low dosage of bone powder extracts causing a metabolic adaptation hallmarked by stimulation of the mitochondrial respiration and enhanced expression of mitochondriogenic factors in particular in cells challenged with oxytetracycline-free bone extract. Conversely, a higher dosage of bone powder extracts, regardless of their source, caused a progressive inhibition of mitochondrial respiration and glycolysis, ultimately leading to cell death. No significant effects of the pure oxytetracycline were observed. Conclusion: Bone powder, regardless of chicken treatment, contains and releases factors/chemicals responsible for the observed effects on energy metabolism. Quantitative differential effects appear to depend on biochemical alterations in the bone matrix caused by antibiotics rather than antibiotics themselves

    Management of low rectal cancer complicating ulcerative colitis: Proposal of a treatment algorithm

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    Low rectal Carcinoma arising at the background of Ulcerative Colitis poses significant management challenges to the clinicians. The complex decision-making requires discussion at the multidisciplinary team meeting. The published literature is scarce, and there are significant variations in the management of such patients. We reviewed treatment protocols and operative strategies; with the aim of providing a practical framework for the management of low rectal cancer complicating UC. A practical treatment algorithm is proposed

    Feasibility and outcomes of ERAS protocol in elective cT4 colorectal cancer patients: results from a single-center retrospective cohort study

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    Background Programs of Enhanced Recovery After Surgery reduces morbidity and shorten recovery in patients undergoing colorectal resections for cancer. Patients presenting with more advanced disease such as T4 cancers are frequently excluded from undergoing ERAS programs due to the difficulty in applying established protocols. The primary aim of this investigation was to evaluate the possibility of applying a validated ERAS protocol in patients undergoing colorectal resection for T4 colon and rectal cancer and to evaluate the short-term outcome. Methods Single-center, retrospective cohort study. All patients with a clinical diagnosis of stage T4 colorectal cancer undergoing surgery between November 2016 and January 2020 were treated following the institutional fast track protocol without exclusion. Short-term postoperative outcomes were compared to those of a control group treated with conventional care and that underwent surgical resection for T4 colorectal cancer at the same institution from January 2010 to October 2016. Data from both groups were collected retrospectively from a prospectively maintained database. Results Eighty-two patients were diagnosed with T4 cancer, 49 patients were included in the ERAS cohort and 33 in the historical conventional care cohort. Both, the mean time of tolerance to solid food diet and postoperative length of stay were significantly shorter in the ERAS group than in the control group (3.14 +/- 1.76 vs 4.8 +/- 1.52; p < 0.0001 and 6.93 +/- 3.76 vs 9.50 +/- 4.83; p = 0.0084 respectively). No differences in perioperative complications were observed. Conclusions Results from this cohort study from a single-center registry support the thesis that the adoption of the ERAS protocol is effective and applicable in patients with colorectal cancer clinically staged T4, reducing significantly their length of stay and time of tolerance to solid food diet, without affecting surgical postoperative outcomes

    The Ricci flow on noncommutative two-tori

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    In this paper we construct a version of Ricci flow for noncommutative 2-tori, based on a spectral formulation in terms of the eigenvalues and eigenfunction of the Laplacian and recent results on the Gauss-Bonnet theorem for noncommutative tori.Comment: 18 pages, LaTe

    Molecular analysis of the apoptotic effects of BPA in acute myeloid leukemia cells

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    <p>Abstract</p> <p>Background:</p> <p>BPA (bisphenol A or 2,2-bis(4-hydroxy-phenol)propane) is present in the manufacture of polycarbonate plastic and epoxy resins, which can be used in impact-resistant safety equipment and baby bottles, as protective coatings inside metal food containers, and as composites and sealants in dentistry. Recently, attention has focused on the estrogen-like and carcinogenic adverse effects of BPA. Thus, it is necessary to investigate the cytotoxicity and apoptosis-inducing activity of this compound.</p> <p>Methods:</p> <p>Cell cycle, apoptosis and differentiation analyses; western blots.</p> <p>Results:</p> <p>BPA is able to induce cell cycle arrest and apoptosis in three different acute myeloid leukemias. Although some granulocytic differentiation concomitantly occurred in NB4 cells upon BPA treatment, the major action was the induction of apoptosis. BPA mediated apoptosis was caspase dependent and occurred by activation of extrinsic and intrinsic cell death pathways modulating both FAS and TRAIL and by inducing BAD phosphorylation in NB4 cells. Finally, also non genomic actions such as the early decrease of both ERK and AKT phosphorylation were induced by BPA thus indicating that a complex intersection of regulations occur for the apoptotic action of BPA.</p> <p>Conclusion:</p> <p>BPA is able to induce apoptosis in leukemia cells via caspase activation and involvement of both intrinsic and extrinsic pathways of apoptosis.</p
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