53 research outputs found
Fully non-Gaussian Scalar-Induced Gravitational Waves
No full textScalar -Induced Gravitational Waves (SIGWs) represent a particular class of primordial signals which are sourced at second -order in perturbation theory whenever a scalar fluctuation of the metric is present. They form a guaranteed Stochastic Gravitational Wave Background (SGWB) that, depending on the amplification of primordial scalar fluctuations, can be detected by GW detectors. The amplitude and the frequency shape of the scalar -induced SGWB can be influenced by the statistical properties of the scalar density perturbations. In this work we study the intuitive physics behind SIGWs and we analyze the imprints of local non-Gaussianity of the primordial curvature perturbation on the GW spectrum. We consider all the relevant non -Gaussian contributions up to fifth -order in the scalar seeds without any hierarchy, and we derive the related GW energy density ohm GW ( f ). We perform a Fisher matrix analysis to understand to which accuracy non-Gaussianity can be constrained with the LISA detector, which will be sensitive in the milli -Hertz frequency band. We find that LISA, neglecting the impact of astrophysical foregrounds, will be able to measure the amplitude, the width and the peak of the spectrum with an accuracy up to O(10 - 4 ), while non-Gaussianity can be measured up to O(10 - 3 ). Finally, we discuss the implications of our non-Gaussianity expansion on the fraction of Primordial Black Holes
Cosmology with Pulsar Timing Array: the case of scalar-induced gravitational waves
No full textreservedGravitational Waves (GWs) constitute a unique window on the very early universe, probing scales that are inaccessible even to Cosmic Microwave Background (CMB) experiments. Scalar-induced GWs represent a particular class of GWs which are sourced at second-order in perturbation theory whenever a scalar fluctuation of the metric is present. In this work we study the intuitive physics behind induced GWs and the construction of the power spectra, analyzing the imprints of local non-Gaussianity of the primordial curvature perturbation on the GW spectrum. For the first time we consider all the relevant non-Gaussian contributions up to third-order in the scalar seeds and we derive the related GW energy density ΩGW(k). We consider different types of primordial curvature power spectra and we assume radiation domination at the time of GW production.
The goal of this work is to understand if these scalar-induced GWs and primordial non-Gaussianity can be probed by Pulsar Timing Array (PTA) experiments, which work in the nano-Hertz frequency range
Regulation of VEGFR2 signaling in angiogenesis and vascular permeability
No full textAngiogenesis and vascular permeability occur in physiological and pathological conditions. Angiogenesis denotes the process of blood vessel formation from preexisting quiescent vessels. Angiogenesis is initiated by proangiogenic factors, inducing endothelial cell sprouting, migration and anastomosis, followed by regression of the new vessels or maturation into a quiescent status. Vascular permeability is the process where blood vessels exchange nutrients, solutes and inflammatory cells with the surrounding tissue. Small molecules freely cross the endothelial wall, however macromolecules and cells leak out from the vasculature only after stimulation by certain factors, including VEGF. Angiogenesis and vascular permeability are tightly regulated physiological processes, but uncontrolled angiogenesis and excessive leakage lead to pathological conditions and the progression of several diseases. VEGF and its receptor VEGFR2 are critical players in angiogenesis and in vascular permeability. The binding of the ligand to the receptor is not the only event involved in the activation and regulation of the signaling cascade. Coreceptors, kinases, phosphatases, and other proteins involved in the trafficking of the complex modulate the signal amplitude and duration. VEGF/VEGFR2 complex combined with the coreceptor NRP1 has a strong pro-angiogenic action and a critical role in angiogenesis. Both VEGFR2 and NRP1 bind VEGF and can present VEGF in cis, when both VEGFR2 and NRP1 are expressed on the same endothelial cell or in trans, when NRP1 is expressed on an adjacent endothelial cell or another type of cell. Y949 and Y1212 are two of the main phosphorylation sites of VEGFR2 induced by VEGFA. The binding of phosphorylated Y949 to the SH2 domain of TSAd regulates vascular permeability leading to Src activation and adherens junction opening in vitro. Phospho-Y1212 is implicated in actin stress fiber remodeling via the adapter Nck, affecting the actin cytoskeleton and endothelial cell migration in vitro. Paladin is a vascular-enriched phosphatase-domain containing protein without reported phosphatase activity and is a negative regulator of insulin receptor and Toll-like receptor 9 signaling. In this thesis work, I have investigated the spatial dynamics of NRP1/VEGFR2 complex formation (in cis and in trans) for coordinating VEGF-mediated angiogenesis in physiological and in pathological conditions (Paper I). I have studied, in vivo, the role of VEGFR2 Y949 in vascular permeability and metastatic spread (Paper II) and the role of VEGFR2 Y1212 in angiogenic remodeling and vessel stability (Paper III). Furthermore, I have examined paladin’s role in regulating VEGF/VEGFR2 signaling and VE-cadherin junction stability, in angiogenic sprouting and vascular permeability (Paper IV). In conclusion, VEGF/VEGFR2 signaling is regulated by a multifactor system and each individual regulatory mechanism leads to a specific outcome in angiogenesis, vascular permeability and vessel stability
Hoffa’s fat pad thickness: a measurement method with sagittal MRI sequences
No full textBackground: Hoffa’s fat pad is a structure located within the fibrous joint capsule of the knee joint, but outside the synovial cavity. It plays an important biomechanical and metabolic role in knee joint, reducing the impact of forces generated by loading and producing cytokines. Changes in its size can induce modifications in the knee homeostasis. However, a great variability exists regarding its measurements. This work aims to evaluate the reliability of a measurement method of Hoffa’s fat pad dimensions through MRI. Methods: 3T sagittal IW 2D TSE fat-suppressed MRI sequences, taken from the OAI (Osteoarthritis initiative) database, of 191 male and female patients, aged between 40 and 80 years, were analysed; a manual measurement of the thickness of Hoffa’s fat pad of each subject was then performed by two different readers. The interobserver reliability and intraobserver reliability of the measurements were described by coefficient of variation (CV), Pearson correlation and Bland–Altman plots. Results: All statistical analyses have shown that not significant intra- or interobservers differences were evident (intraobserver CV % for the first observer was 2.17% for the right knee and 2.24% for the left knee, while for the second observer 2.31% for the right knee and 2.24% for the left knee; linear correlation was for the first observer r = 0.96 for the right knee and r = 0.96 for the left knee, while for the second observer r = 0.97 for the right knee and r = 0.96 for the left knee; in addition, the interobserver CV % was 1.25% for the right knee and 1.21% for the left knee and a high interobserver linear correlation was found: r = 0.97 for the right knee and r = 0.96 for the left knee). All results suggest that this manual measurement method of Hoffa’s fat pad thickness can be performed with satisfactory intra- and interobserver reliability. Conclusions: Hoffa’s fat pad thickness can be measured, using sagittal MRI images, with this manual method that represents, for his high reliability, an effective means for the study of this anatomical structure. © 2021, The Author(s)
Diagnostic, therapeutic and healthcare management protocols in thyroid surgery: 3rd consensus conference of the italian association of endocrine surgery units (U.E.C. CLUB)
No full textAbstract
Aim: To update the Diagnostic-Therapeutic-Healthcare Protocol (Protocollo Diagnostico-Terapeutico-Assistenziale, PDTA) created by the U.E.C. CLUB (Association of the Italian Endocrine Surgery Units) during the I Consensus Conference in 2008. Methods: In the preliminary phase, the II Consensus involved a selected group of experts; the elaboration phase was conducted via e-mail among all members; the conclusion phase took place during the X National Congress of the U.E.C. CLUB. The following were examined: diagnostic pathway and clinical evaluation; mode of admission and waiting time; therapeutic pathway (patient preparation for surgery, surgical treatment, postoperative management, management of major complications); hospital discharge and patient information; outpatient care and follow-up. Conclusions: The PDTA for parathyroid surgery approved by the II Consensus Conference (June 2013) is the official PDTA of the U.E.C. CLUB. © Italian Society of Endocrinology (SIE) 2013
A Novel Technique of Digestive Anastomosis Reinforcement Using Bovine Pericardium Patch
No full textBrief Reports should be submitted online to www.editorialmanager.com/ amsurg. (See details online under ‘‘Instructions for Authors’’.) They should be no more than 4 double-spaced pages with no Abstract or sub-headings, with a maximum of four (4) references. If figures are included, they should be limited to two (2). The cost of printing color figures is the responsibility of the author. In general, authors of case reports should use the Brief Report format
Fully non-Gaussian Scalar-Induced Gravitational Waves
No full textScalar-induced Gravitational Waves (SIGWs) represent a particular class of
primordial signals which are sourced at second-order in perturbation theory
whenever a scalar fluctuation of the metric is present. They form a guaranteed
Stochastic Gravitational Wave Background (SGWB) that, depending on the
amplification of primordial scalar fluctuations, can be detected by GW
detectors. The amplitude and the frequency shape of the scalar-induced SGWB can
be influenced by the statistical properties of the scalar density
perturbations. In this work we study the intuitive physics behind SIGWs and we
analyze the imprints of local non-Gaussianity of the primordial curvature
perturbation on the GW spectrum. We consider all the relevant non-Gaussian
contributions up to fifth-order in the scalar seeds without any hierarchy, and
we derive the related GW energy density . We perform a
Fisher matrix analysis to understand to which accuracy non-Gaussianity can be
constrained with the LISA detector, which will be sensitive in the milli-Hertz
frequency band. We find that LISA, neglecting the impact of astrophysical
foregrounds, will be able to measure the amplitude, the width and the peak of
the spectrum with an accuracy up to , while
non-Gaussianity can be measured up to . Finally, we
discuss the implications of our non-Gaussianity expansion on the fraction of
Primordial Black Holes.Comment: 39 pages, 23 figures + Appendice
Regulation of VEGFR2 signaling in angiogenesis and vascular permeability [Elektronisk resurs]
No full textAngiogenesis and vascular permeability occur in physiological and pathological conditions. Angiogenesis denotes the process of blood vessel formation from preexisting quiescent vessels. Angiogenesis is initiated by proangiogenic factors, inducing endothelial cell sprouting, migration and anastomosis, followed by regression of the new vessels or maturation into a quiescent status. Vascular permeability is the process where blood vessels exchange nutrients, solutes and inflammatory cells with the surrounding tissue. Small molecules freely cross the endothelial wall, however macromolecules and cells leak out from the vasculature only after stimulation by certain factors, including VEGF. Angiogenesis and vascular permeability are tightly regulated physiological processes, but uncontrolled angiogenesis and excessive leakage lead to pathological conditions and the progression of several diseases.VEGF and its receptor VEGFR2 are critical players in angiogenesis and in vascular permeability. The binding of the ligand to the receptor is not the only event involved in the activation and regulation of the signaling cascade. Coreceptors, kinases, phosphatases, and other proteins involved in the trafficking of the complex modulate the signal amplitude and duration.VEGF/VEGFR2 complex combined with the coreceptor NRP1 has a strong pro-angiogenic action and a critical role in angiogenesis. Both VEGFR2 and NRP1 bind VEGF and can present VEGF in cis, when both VEGFR2 and NRP1 are expressed on the same endothelial cell or in trans, when NRP1 is expressed on an adjacent endothelial cell or another type of cell.Y949 and Y1212 are two of the main phosphorylation sites of VEGFR2 induced by VEGFA. The binding of phosphorylated Y949 to the SH2 domain of TSAd regulates vascular permeability leading to Src activation and adherens junction opening in vitro. Phospho-Y1212 is implicated in actin stress fiber remodeling via the adapter Nck, affecting the actin cytoskeleton and endothelial cell migration in vitro.Paladin is a vascular-enriched phosphatase-domain containing protein without reported phosphatase activity and is a negative regulator of insulin receptor and Toll-like receptor 9 signaling.In this thesis work, I have investigated the spatial dynamics of NRP1/VEGFR2 complex formation (in cis and in trans) for coordinating VEGF-mediated angiogenesis in physiological and in pathological conditions (Paper I). I have studied, in vivo, the role of VEGFR2 Y949 in vascular permeability and metastatic spread (Paper II) and the role of VEGFR2 Y1212 in angiogenic remodeling and vessel stability (Paper III). Furthermore, I have examined paladin’s role in regulating VEGF/VEGFR2 signaling and VE-cadherin junction stability, in angiogenic sprouting and vascular permeability (Paper IV).In conclusion, VEGF/VEGFR2 signaling is regulated by a multifactor system and each individual regulatory mechanism leads to a specific outcome in angiogenesis, vascular permeability and vessel stability.</p
- …
