Group Validation in Recommender Systems: Framework for Multi-layer Performance Evaluation

Interpreting the performance results of models that attempt to realize user behavior in platforms that employ recommenders is a big challenge that researchers and practitioners continue to face. Although current evaluation tools possess the capacity to provide solid general overview of a system's performance, they still lack consistency and effectiveness in their use as evident in most recent studies on the topic. Current traditional assessment techniques tend to fail to detect variations that could occur on smaller subsets of the data and lack the ability to explain how such variations affect the overall performance. In this article, we focus on the concept of data clustering for evaluation in recommenders and apply a neighborhood assessment method for the datasets of recommender system applications. This new method, named neighborhood-based evaluation, aids in better understanding critical performance variations in more compact subsets of the system to help spot weaknesses where such variations generally go unnoticed with conventional metrics and are typically averaged out. This new modular evaluation layer complements the existing assessment mechanisms and provides the possibility of several applications to the recommender ecosystem such as model evolution tests, fraud/attack detection and a possibility for hosting a hybrid model setup

A study of serum levels of B cell-attracting chemokine-13 (CXCL 13) and rheumatologic manifestations of chronic hepatitis C virus infection in a cohort of Egyptian patients

AbstractMany rheumatologic manifestations have been associated with Hepatitis C virus (HCV) infection including; arthralgia, myalgia, fatigue, fibromyalgia, vasculitis, and sicca syndrome. The relationship between emergence and persistence of intrahepatic or circulating B cell clonotypes and HCV infection is still unknown. However accumulating evidences indicate that certain chemokines play a critical role in providing the appropriate environment for activation and expansion of naïve lymphocytes, one of these chemokines is B cell-attracting chemokine-13 (CXCL13).CXCL13 is a major regulator of B-cell trafficking. This study evaluates circulating levels of CXCL13 protein in chronically HCV-infected Egyptian patients compared with healthy controls and its association with articular synovial hypertrophy. Rheumatic manifestations were present in 85% of patients; included fatigue (20%), arthralgia (the commonest manifestation) (65%), fibromyalgia (22%), myalgia (37%), Rayunad’s phenomenon (10%), peripheral neuropathy and arthritis (2.5%), and tendenitis (7.5). Cryoglobulins recorded in this study were of type II & III mixed cryoglobulins (MC) positive in 25% all of which showed positive rheumatoid factor (RF). Significant low levels of C3 and C4 were reported in the patient group. CXCL13 serum levels were significantly high in the patient group especially in the MC positive group compared to controls. The highest levels of CXCL13 were significantly associated with rheumatologic manifestations with or without mixed cryoglobulinemia and significantly associated with articular synovial hypertrophy

Predictive model of 2-cyclohexylthiophene for corrosion inhibition in mild steel using computational method

Corrosion inhibition activity of 2-cyclohexylthiophene (2CHT) for mild steel in acidic media was predicted using QSAR tool. The model used two descriptors namely; Moran autocorrelation of lag4 weighted by mass (MATS4M) which explained the linearity and branching of the compounds and largest eigen values n3 of burden matrix weighted by mass (SPMAX3-Bh(m)) describes the nature and size of the neighboring atom. The modeling results revealed the potential of the compounds as a good corrosion inhibitor with percentage inhibition efficiency (%IE) of 76.5%. Quantum chemical calculation using DFT with 6-311G++(d,p) basis was used to evaluate the performance of the predicted compound as corrosion inhibitor by quantum chemical parameters such as EHUMO, ELUMO, Energy gap (Egap), hardness (?), softness (S), dipole moment (µ), electronegativity (X), electron affinity (A), ionization energy (I) and total energy (TE). The results obtained from quantum chemical parameters were found to be consistent with predicted result

Ulcerative Colitis-Associated Colorectal Cancer Prevention by 5-Aminosalicylates: Current Status and Perspectives

International audienc

Indirect dark matter searches as a probe of degenerate particle spectra

We consider the possibility that the cosmological dark matter consists of particles very close in mass to new colored particles below the TeV scale. While such a scenario is inherently difficult to directly confirm at colliders, we find that indirect dark matter searches may be a powerful alternative. In particular, we show that in this case dark matter annihilation to quark-quark-gluon final states can give rise to significant antiproton (but also gamma-ray) fluxes, and compare the resulting constraints to bounds from direct searches at LEP, the Tevatron and the LHC. For supersymmetric neutralinos degenerate with squarks, e.g., antiprotons can give rise to more stringent constraints for masses below around 45-80 GeV.Comment: 6 pages, 4 figures; minor updates to match the published versio

Detecting light leptophilic gauge boson at BESIII detector

The $O(GeV)$ extra $U(1)$ gauge boson named U-boson, has been proposed to mediate the interaction among leptons and dark matter (DM), in order to account for the observations by PAMELA and ATIC. In such kind of models, the extra U(1) gauge group can be chosen as $U(1)_{L_i-L_j}$ with $L_i$ the $i-$th generation lepton number. This anomaly-free model provides appropriate dark matter relic density and boost factor required by experiments. In this work the observability of such kind of U-boson at BESIII detector is investigated through the processes $e^ + e^ - \to U\gamma$, followed by $U\to e^+e^-$, $U\to \mu^+\mu^-$ and $U\to \nu\overline{\nu}$. In the invisible channel where U-boson decays into neutrinos, BESIII can measure the coupling of the extra $U(1)$ down to $O(10^{- 4}) \sim O(10^{- 5})$ because of the low Standard Model backgrounds. In the visible channel where U-boson decays into charged lepton pair, BESIII can only measure the coupling down to $O(10^{- 3}) \sim O(10^{- 4})$ due to the large irreducible QED backgrounds.Comment: 7pages, 9figures; V2: SecIII corrected, discussions adde

Burnout among surgeons before and during the SARS-CoV-2 pandemic: an international survey

Background: SARS-CoV-2 pandemic has had many significant impacts within the surgical realm, and surgeons have been obligated to reconsider almost every aspect of daily clinical practice. Methods: This is a cross-sectional study reported in compliance with the CHERRIES guidelines and conducted through an online platform from June 14th to July 15th, 2020. The primary outcome was the burden of burnout during the pandemic indicated by the validated Shirom-Melamed Burnout Measure. Results: Nine hundred fifty-four surgeons completed the survey. The median length of practice was 10 years; 78.2% included were male with a median age of 37 years old, 39.5% were consultants, 68.9% were general surgeons, and 55.7% were affiliated with an academic institution. Overall, there was a significant increase in the mean burnout score during the pandemic; longer years of practice and older age were significantly associated with less burnout. There were significant reductions in the median number of outpatient visits, operated cases, on-call hours, emergency visits, and research work, so, 48.2% of respondents felt that the training resources were insufficient. The majority (81.3%) of respondents reported that their hospitals were included in the management of COVID-19, 66.5% felt their roles had been minimized; 41% were asked to assist in non-surgical medical practices, and 37.6% of respondents were included in COVID-19 management. Conclusions: There was a significant burnout among trainees. Almost all aspects of clinical and research activities were affected with a significant reduction in the volume of research, outpatient clinic visits, surgical procedures, on-call hours, and emergency cases hindering the training. Trial registration: The study was registered on clicaltrials.gov "NCT04433286" on 16/06/2020