Network robustness improvement via long-range links

Abstract Many systems are today modelled as complex networks, since this representation has been proven being an effective approach for understanding and controlling many real-world phenomena. A significant area of interest and research is that of networks robustness, which aims to explore to what extent a network keeps working when failures occur in its structure and how disruptions can be avoided. In this paper, we introduce the idea of exploiting long-range links to improve the robustness of Scale-Free (SF) networks. Several experiments are carried out by attacking the networks before and after the addition of links between the farthest nodes, and the results show that this approach effectively improves the SF network correct functionalities better than other commonly used strategies

Transplantation and young surgeons in italy

The relation between young surgeons and transplantation has always been a "love and hate" one. Until a few years ago this branch of surgery was seen as pioneering, with extreme and and extensive training, and was reserved to few elected members. Nowadays things are different. In this article we try to understand the true reasons that young Italian surgeons avoid transplantation surgery

Sutureless jejuno-jejunal anastomosis in gastric cancer patients: a comparison with handsewn procedure in a single institute

Background: The biofragmentable anastomotic ring has been used to this day for various types of anastomosis in the gastrointestinal tract, but it has not yet achieved widespread acceptance among surgeons. The purpose of this retrospective study is to compare surgical outcomes of sutureless with suture method of Roux-and-Y jejunojejunostomy in patients with gastric cancer.Methods: Two groups of patients were obtained based on anastomosis technique (sutureless group versus hand sewn group): perioperative outcomes were recorded for every patient.Results: The mean time spent to complete a sutureless anastomosis was 11 +/- 4 min, whereas the time spent to perform hand sewn anastomosis was 23 +/- 7 min. Estimated intraoperative blood loss was 178 +/- 32ml in the sutureless group and 182 +/- 23ml in the suture-method group with no significant differences. No complications were registered related to enteroanastomosis. Intraoperative mortality was none for both groups.Conclusions: The Biofragmentable Anastomotic Ring offers a safe and time-saving method for the jejuno-jejunal anastomosis in gastric cancer surgery, and for this purpose the ring has been approved as a standard method in our clinic. Nevertheless currently there are few studies on upper gastrointestinal sutureless anastomoses and this could be the reason for the low uptake of this device

Large symptomatic gastric diverticula: two case reports and a brief review of literature

Gastric diverticula are rare and uncommon conditions. Most gastric diverticula are asymptomatic. When symptoms arise, they are most commonly upper abdominal pain, nausea and emesis, while dyspepsia and vomiting are less common. Occasionally, patients with gastric diverticula can have dramatic presentations related to massive bleeding or perforation. The diagnosis may be difficult, as symptoms can be caused by more common gastrointestinal pathologies and only aggravated by diverticula. The appropriate management of diverticula depends mainly on the symptom pattern and as well as diverticulum size. There is no specific therapeutic strategy for an asymptomatic diverticulum. Although some authors support conservative therapy with antacids, this provides only temporary symptom relief since it is not able to resolve the underlying pathology. Surgical resection is the mainstay of treatment when the diverticulum is large, symptomatic or complicated by bleeding, perforation or malignancy, with over two-thirds of patients remaining symptom-free after surgery, while laparoscopic resection, combined with intraoperative endoscopy, is a safe and feasible approach with excellent outcomes. Here, we present two cases of uncommon large symptomatic gastric diverticula with a discussion of the cornerstones in management and report a minimally invasive solution, with a brief review of the literature. (C) 2013 Baishideng. All rights reserved

Comparison of the 6th and 7th editions of the AJCC/UICC TNM staging system for gastric cancer focusing on the "N" parameter-related survival: the monoinstitutional NodUs Italian study

Background: A large number of Asian population studies examined the difference between the 6th and the 7th tumor, node, metastasis (TNM) while it is still poorly validated among Caucasian populations. This is a retrospective study aimed at investigating the efficacy of the 7th edition American Joint Committee on Cancer (AJCC)/Union for International Cancer Control (UICC) staging system for gastric cancer focusing on the "N" parameter-related survival for prognostic assessment in gastric cancer patients of a single Western high-volume institution.Methods: From January 2002 to December 2009, the data of 274 patients with gastric cancer who underwent gastric surgery at the 8th General and Gastrointestinal Surgical Centre of the Second University of Naples were analyzed retrospectively. We collected data for patient demographics, tumor characteristics, surgical characteristics, and TNM stage. Particularly, the nodal status, with the number of dissected nodes and metastatic nodes, was reviewed from the pathology records. The same patient dataset was used to stage patients according to both the 6th and 7th edition criteria.Results: Age at surgery, tumor location, histological grade, Lauren's classification subtypes, and 6th and 7th AJCC/UICC N categories were found to have statistically significant associations with overall survival on univariate analysis. In the 6th edition staging system, the Kaplan-Meier plot did not show significant overlapped survival curves: significant differences were found between N0 and N1, P<.001; N1 and N2, P=.04; and N2 and N3, P<.001. On the contrary, in the 7th edition, among all five substages, there were similar survival curves between N categories 2 and 3a (P=.98) with a statistically significant discriminatory ability only between N1 versus N3b and N2 versus N3b (P=.02 and .04, respectively).Conclusions: Based on analysis, we found that several clinicopathological variables, especially histological grade and Lauren's classification, were significant prognostic factors in our database. The 6th and 7th AJCC/UICC N classifications represent significantly independent prognostic factors, and the 6th AJCC/UICC N classification seems to be superior to the 7th AJCC/UICC N classification in terms of uniformity, differentiation, and monotonicity of gradients

Constraints on the cosmic expansion history from GWTC-3

We use 47 gravitational-wave sources from the Third LIGO-Virgo-KAGRA Gravitational-Wave Transient Catalog (GWTC-3) to estimate the Hubble parameter $H(z)$, including its current value, the Hubble constant $H_0$. Each gravitational-wave (GW) signal provides the luminosity distance to the source and we estimate the corresponding redshift using two methods: the redshifted masses and a galaxy catalog. Using the binary black hole (BBH) redshifted masses, we simultaneously infer the source mass distribution and $H(z)$. The source mass distribution displays a peak around $34\, {\rm M_\odot}$, followed by a drop-off. Assuming this mass scale does not evolve with redshift results in a $H(z)$ measurement, yielding $H_0=68^{+12}_{-7} {\rm km\,s^{-1}\,Mpc^{-1}}$ ($68\%$ credible interval) when combined with the $H_0$ measurement from GW170817 and its electromagnetic counterpart. This represents an improvement of 17% with respect to the $H_0$ estimate from GWTC-1. The second method associates each GW event with its probable host galaxy in the catalog GLADE+, statistically marginalizing over the redshifts of each event's potential hosts. Assuming a fixed BBH population, we estimate a value of $H_0=68^{+8}_{-6} {\rm km\,s^{-1}\,Mpc^{-1}}$ with the galaxy catalog method, an improvement of 42% with respect to our GWTC-1 result and 20% with respect to recent $H_0$ studies using GWTC-2 events. However, we show that this result is strongly impacted by assumptions about the BBH source mass distribution; the only event which is not strongly impacted by such assumptions (and is thus informative about $H_0$) is the well-localized event GW190814

Search for continuous gravitational wave emission from the Milky Way center in O3 LIGO--Virgo data

We present a directed search for continuous gravitational wave (CW) signals emitted by spinning neutron stars located in the inner parsecs of the Galactic Center (GC). Compelling evidence for the presence of a numerous population of neutron stars has been reported in the literature, turning this region into a very interesting place to look for CWs. In this search, data from the full O3 LIGO--Virgo run in the detector frequency band $[10,2000]\rm~Hz$ have been used. No significant detection was found and 95$\%$ confidence level upper limits on the signal strain amplitude were computed, over the full search band, with the deepest limit of about $7.6\times 10^{-26}$ at $\simeq 142\rm~Hz$. These results are significantly more constraining than those reported in previous searches. We use these limits to put constraints on the fiducial neutron star ellipticity and r-mode amplitude. These limits can be also translated into constraints in the black hole mass -- boson mass plane for a hypothetical population of boson clouds around spinning black holes located in the GC.Comment: 25 pages, 5 figure

Search for Eccentric Black Hole Coalescences during the Third Observing Run of LIGO and Virgo

Despite the growing number of confident binary black hole coalescences observed through gravitational waves so far, the astrophysical origin of these binaries remains uncertain. Orbital eccentricity is one of the clearest tracers of binary formation channels. Identifying binary eccentricity, however, remains challenging due to the limited availability of gravitational waveforms that include effects of eccentricity. Here, we present observational results for a waveform-independent search sensitive to eccentric black hole coalescences, covering the third observing run (O3) of the LIGO and Virgo detectors. We identified no new high-significance candidates beyond those that were already identified with searches focusing on quasi-circular binaries. We determine the sensitivity of our search to high-mass (total mass $M>70$ $M_\odot$) binaries covering eccentricities up to 0.3 at 15 Hz orbital frequency, and use this to compare model predictions to search results. Assuming all detections are indeed quasi-circular, for our fiducial population model, we place an upper limit for the merger rate density of high-mass binaries with eccentricities $0 < e \leq 0.3$ at $0.33$ Gpc$^{-3}$ yr$^{-1}$ at 90\% confidence level.Comment: 24 pages, 5 figure