New hyperbolic 4-manifolds of low volume

We prove that there are at least 2 commensurability classes of minimal-volume hyperbolic 4-manifolds. Moreover, by applying a well-known technique due to Gromov and Piatetski-Shapiro, we build the smallest known non-arithmetic hyperbolic 4-manifold.Comment: 21 pages, 6 figures. Added the Coxeter diagrams of the commensurability classes of the manifolds. New and better proof of Lemma 2.2. Modified statements and proofs of the main theorems: now there are two commensurabilty classes of minimal volume manifolds. Typos correcte

Compact hyperbolic manifolds without spin structures

We exhibit the first examples of compact orientable hyperbolic manifolds that do not have any spin structure. We show that such manifolds exist in all dimensions $n \geq 4$. The core of the argument is the construction of a compact orientable hyperbolic $4$-manifold $M$ that contains a surface $S$ of genus $3$ with self intersection $1$. The $4$-manifold $M$ has an odd intersection form and is hence not spin. It is built by carefully assembling some right angled $120$-cells along a pattern inspired by the minimum trisection of $\mathbb{C}\mathbb{P}^2$. The manifold $M$ is also the first example of a compact orientable hyperbolic $4$-manifold satisfying any of these conditions: 1) $H_2(M,\mathbb{Z})$ is not generated by geodesically immersed surfaces. 2) There is a covering $\tilde{M}$ that is a non-trivial bundle over a compact surface.Comment: 23 pages, 16 figure

Comment

A chloride-based chemical-vapor-deposition (CVD) process has been successfully used to grow very high quality 3C-SiC epitaxial layers on on-axis α-SiC substrates. An accurate process parameters study was performed testing the effect of temperature, surface preparation, precursor ratios, nitrogen addition, and substrate polytype and polarity. The 3C layers deposited showed to be largely single-domain material of very high purity and of excellent electrical characteristics. A growth rate of up to 10 μm/h and a low background doping enable deposition of epitaxial layers suitable for MOSFET devices

Convex plumbings in closed hyperbolic 4-manifolds

We show that every plumbing of disc bundles over surfaces whose genera satisfy a simple inequality may be embedded as a convex submanifold in some closed hyperbolic four-manifold. In particular its interior has a geometrically finite hyperbolic structure that covers a closed hyperbolic four-manifold.Comment: 18 pages, 11 figure

Acquired and inherited risk factors for splanchnic venous thrombosis

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Transperineal excision of malignant peripheral nerve sheath tumors of the ischiorectal fossa: Case report of a rare tumor in a frequently forgotten anatomical region

Introduction and importance: Malignant peripheral nerve sheath tumor is an aggressive tumor that arises from peripheral nerves. Frequently associated with neurofibromatosis, its common localization is in the extremities, trunk (with paravertebral regions), neck and head. Some cases have been found in the pelvis or uterus. In this case report we illustrate one of the rarest localization of this type of tumor in the ischiorectal fossa, with the full recovery of the patient after surgical excision and radiotherapy. Case presentation: A 61-year-old woman showed a lump near the anus which was initially diagnosed as a lipoma of the right ischiorectal fossa, by Computed Tomography scan. The tumor was completely removed with a minimal skin incision, and the patient had a complete recovery. Only the pathological examination determined the diagnosis of malignant peripheral nerve sheath tumor, in this unusual localization. In consideration of its high aggressiveness the patient underwent radiotherapy. After more than two years of follow-up there is no sign of recurrence. Discussion: In sites far from branches of nerves, malignant peripheral nerve sheath tumors can be considered episodic. Ischiorectal fossa is a rare localization, and the differential diagnosis from benign mesenchymal cell tumors can be challenging. When possible, a biopsy should be performed before surgery. Conclusion: Surgical excision of tumors in ischiorectal fossa should be always complete, in consideration of possible histological surprise

Mediterranean jellyfish as novel food: effects of thermal processing on antioxidant, phenolic, and protein contents

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Design Optimization of Heat Wheels for Energy Recovery in HVAC Systems

Air to air heat exchangers play a crucial role in mechanical ventilation equipment, due to the potential primary energy savings both in case of refurbishment of existing buildings or in case of new ones. In particular, interest in heat wheels is increasing due to their low pressure drop and high effectiveness. In this paper a detailed optimization of design parameters of heat wheels is performed in order to maximize sensible effectiveness and to minimize pressure drop. The analysis is carried out through a one dimensional lumped parameters heat wheel model, which solves heat and mass transfer equations, and through appropriate correlations to estimate pressure drop. Simulation results have been compared with experimental data of a heat wheel tested in specific facilities, and good agreement is attained. The device optimization is performed through the variation of main design parameters, such as heat wheel length, channel base, height and thickness and for different operating conditions, namely the air face velocity and the revolution speed. It is shown that the best configurations are achieved with small channel thickness and, depending on the required sensible effectiveness, with appropriate values of wheel length and channel base and height

KRAS is a molecular determinant of platinum responsiveness in glioblastoma

Background: KRAS is the undisputed champion of oncogenes, and despite its prominent role in oncogenesis as mutated gene, KRAS mutation appears infrequent in gliomas. Nevertheless, gliomas are considered KRAS-driven cancers due to its essential role in mouse malignant gliomagenesis. Glioblastoma is the most lethal primary brain tumor, often associated with disturbed RAS signaling. For newly diagnosed GBM, the current standard therapy is alkylating agent chemotherapy combined with radiotherapy. Cisplatin is one of the most effective anticancer drugs and is used as a first-line treatment for a wide spectrum of solid tumors (including medulloblastoma and neuroblastoma) and many studies are currently focused on new delivery modalities of effective cisplatin in glioblastoma. Its mechanism of action is mainly based on DNA damage, inducing the formation of DNA adducts, triggering a series of signal-transduction pathways, leading to cell-cycle arrest, DNA repair and apoptosis. Methods: Long-term cultures of human glioblastoma, U87MG and U251MG, were either treated with cis-diamminedichloroplatinum (cisplatin, CDDP) and/or MEK-inhibitor PD98059. Cytotoxic responses were assessed by cell viability (MTT), protein expression (Western Blot), cell cycle (PI staining) and apoptosis (TUNEL) assays. Further, gain-of-function experiments were performed with cells over-expressing mutated hypervariable region (HVR) KRASG12V plasmids. Results: Here, we studied platinum-based chemosensitivity of long-term cultures of human glioblastoma from the perspective of KRAS expression, by using CDDP and MEK-inhibitor. Endogenous high KRAS expression was assessed at transcriptional (qPCR) and translational levels (WB) in a panel of primary and long-term glioblastoma cultures. Firstly, we measured immediate cellular adjustment through direct regulation of protein concentration of K-Ras4B in response to cisplatin treatment. We found increased endogenous protein abundance and involvement of the effector pathway RAF/MEK/ERK mitogen-activated protein kinase (MAPK) cascade. Moreover, as many MEK inhibitors are currently being clinically evaluated for the treatment of high-grade glioma, so we concomitantly tested the effect of the potent and selective non-ATP-competitive MEK1/2 inhibitor (PD98059) on cisplatin-induced chemosensitivity in these cells. Cell-cycle phase distribution was examined using flow cytometry showing a significant cell-cycle arrest in both cultures at different percentage, which is modulated by MEK inhibition. Cisplatin-induced cytotoxicity increased sub-G1 percentage and modulates G2/M checkpoint regulators cyclins D1 and A. Moreover, ectopic expression of a constitutively active KRASG12V rescued CDDP-induced apoptosis and different HVR point mutations (particularly Ala 185) reverted this phenotype. Conclusion: These findings warrant further studies of clinical applications of MEK1/2 inhibitors and KRAS as 'actionable target' of cisplatin-based chemotherapy for glioblastoma