An Exact Characterization of the Generalization Error for the Gibbs Algorithm

Various approaches have been developed to upper bound the generalization error of a supervised learning algorithm. However, existing bounds are often loose and lack of guarantees. As a result, they may fail to characterize the exact generalization ability of a learning algorithm.Our main contribution is an exact characterization of the expected generalization error of the well-known Gibbs algorithm (a.k.a. Gibbs posterior) using symmetrized KL information between the input training samples and the output hypothesis. Our result can be applied to tighten existing expected generalization error and PAC-Bayesian bounds. Our approach is versatile, as it also characterizes the generalization error of the Gibbs algorithm with data-dependent regularizer and that of the Gibbs algorithm in the asymptotic regime, where it converges to the empirical risk minimization algorithm. Of particular relevance, our results highlight the role the symmetrized KL information plays in controlling the generalization error of the Gibbs algorithm

Evaluation of liver enzyme levels in workers exposed to vinyl chloride vapors in a petrochemical complex: A cross-sectional study

Background: Polyvinyl chloride is used in production and manufacturing of many essential tools (e.g. plastic pipes, photography films, etc.). Its production is impossible without the use of vinyl chloride monomer (VCM), which can cause liver damage in long-term. In this study we intend to assess the effects of mild to moderate long term exposure to VCM on liver and to assess the importance of liver enzyme measurements as a screening tool. Methods: In this study, liver enzyme levels of 52 workers were compared to 48 control workers using the T-test. The cases all worked in a PVC production unit in a petrochemical complex and the controls were randomly selected from office personnel of the same complex. A questionnaire was also filled in about information such as age, weight, work history, etc. in both groups. Results: Mean comparisons for ALP and GGT using T-test showed statistically significant differences between the two groups. For AST, ALT and bilirubin (total, direct) the mean was higher in the case group but this difference was not statistically significant. Discussion: This study showed that mild exposure to VCM can cause mild liver cholestasis. So, using cholestasis assessment tests such as ALP and GGT should be considered in periodic assessment of liver function in PVC producing units

A computational fluid dynamics study of laminar forced convection improvement of a non-Newtonian hybrid nanofluid within an annular pipe in porous media

Porous inserts and nanofluids are among the conventional methods for the amelioration of heat transfer in industrial systems. The heat transfer rate could also be improved by utilizing porous substances with a higher thermal conductivity in these systems. This research work presents a two-dimensional (2D) numerical examination of the laminar forced convection of an Al2O3-CuO-carboxy methyl cellulose (CMC) non-Newtonian hybrid nanofluid within an annular pipe in a porous medium. The porous medium was inserted within two inner or outer wall cases. For hybrid nanofluid flow modeling in porous media, a Darcy–Brinkman–Forchheimer formulation was employed. Additionally, a power-law technique was utilized as a fluid viscosity model for the considered non-Newtonian fluid. The governing equations were discretized according to the finite volume method (FVM) using the computational fluid dynamics (CFD) software package ANSYS-FLUENT. The cylinder walls’ thermal boundary conditions were exposed to a constant heat flux. For various Darcy numbers, the impacts of different volume fractions of the hybrid nanofluid (0% to 5%), the total Nusselt number, the pressure drop, and the performance number (PN) were evaluated. The outcomes indicate that the heat transfer coefficient increases considerably with a decrease in the Darcy number (0.1 to 0.0001), as well as with an increase in the porous thickness ratio. Moreover, it was found that the nanoparticles’ increased volume fraction would ameliorate the heat transfer and, more considerably, the PN factor. Furthermore, according to the outcomes in both cases I and II for a constant porous thickness ratio and Darcy number (rp=1,Da=0.0001) and a high volume fraction (φ=5%), the maximum total Nusselt number reached 1274.44. Moreover, applying a volume fraction of 5% with Da=0.1 and rp=1 reached the highest value of the PN index equal to 7.61, which is augmented as roughly 88% compared to the case of a zero volume fraction

Comparison of laboratory and daily-life gait speed assessment during on and off states in parkinson’s disease

Accurate assessment of Parkinson’s disease (PD) ON and OFF states in the usual environment is essential for tailoring optimal treatments. Wearables facilitate measurements of gait in novel and unsupervised environments; however, differences between unsupervised and in-laboratory measures have been reported in PD. We aimed to investigate whether unsupervised gait speed discriminates medication states and which supervised tests most accurately represent home perfor-mance. In-lab gait speeds from different gait tasks were compared to home speeds of 27 PD patients at ON and OFF states using inertial sensors. Daily gait speed distribution was expressed in percentiles and walking bout (WB) length. Gait speeds differentiated ON and OFF states in the lab and the home. When comparing lab with home performance, ON assessments in the lab showed moderate-to-high correlations with faster gait speeds in unsupervised environment (r = 0.69; p < 0.001), associated with long WB. OFF gait assessments in the lab showed moderate correlation values with slow gait speeds during OFF state at home (r = 0.56; p = 0.004), associated with short WB. In-lab and daily assessments of gait speed with wearables capture additional integrative aspects of PD, reflecting different aspects of mobility. Unsupervised assessment using wearables adds complementary information to the clinical assessment of motor fluctuations in PD.This research was funded by Keep Control from the EU’s Horizon 2020 (H2020) research and innovation program under the Marie Sklodowska-Curie (MSCA-ITN-ETN), grant number 721577. No other financial support and funding for the preceding twelve months are applied

Squaring the Circle: Geometric Skewness and Symmetry Breaking for Passive Scalar Transport in Ducts and Pipes

We study the role geometry plays in the emergence of asymmetries in diffusing passive scalars advected by pressure-driven flows in ducts and pipes of different aspect ratios. We uncover nonintuitive, multi-time-scale behavior gauged by a new statistic, which we term "geometric skewness" S^{G}, which measures instantaneously forming asymmetries at short times due to flow geometry. This signature distinguishes elliptical pipes of any aspect ratio, for which S^{G}=0, from rectangular ducts whose S^{G} is generically nonzero, and, interestingly, shows that a special duct of aspect ratio ≈0.53335 behaves like a circular pipe as its geometric skewness vanishes. Using a combination of exact solutions, novel short-time asymptotics, and Monte Carlo simulations, we establish the relevant time scales for plateaus and extrema in the evolution of the skewness and kurtosis for our class of geometries. For ducts limiting to channel geometries, we present new exact, single-series formulas for the first four moments on slices used to benchmark Monte Carlo simulations

Evaluation of civil flight deck design using fuzzy logic approach

A good ergonomic design for cockpit can greatly help to improve pilots’ task efficiency and reduce potential human errors, hence increasing safety of flight operations. The ergonomics aspect should be more emphasized nowadays as the cockpit system moves towards more flight automation, particularly regarding the human-machine interactions. In this study, the main objective is to highlight whether there is potential improvement for current cockpit system design. The evaluation process is done using fuzzy logic pattern recognition approach and three evaluation objects have been chosen, which are instrument panel, pedestal panel and pilot's seat. 14 experts are involved in evaluating these objects through a survey that has been distributed to them. 10 evaluation criteria are established for the study and cockpit designs of two existing aircraft series are used in the example case study. All in all, the results highlight that there exists some rooms for improvement for the current cockpit design that should be considered in the future to enhance its efficiency

N�89 and C�274 Truncated Enzymes of Chondroitinase ABC I Regain More Imperturbable Microenvironments Around Structural Components in Comparison to their Wild Type

Immune response stimulation and inactivation of chondroitinase ABC I in physiological condition have been limited its use in various clinical conditions as a bacterial enzyme drug. In the present study, we have investigated some structural and functional features of N�89, C�274 and N�89C�274; three designed truncated cABC I, in order to clarify the unclear role of two terminal parts of cABC I i.e., the 1�89 and 747�1021 amino acids sequences of the full length enzyme through truncation. As a result, the numbers of potential epitopes, the susceptibility to trypsin digestion, ANS fluorescence spectra, and fluorescence quenching using KI and acrylamide were diminished for N�89 and C�274 in comparison to the wild type. Secondary and tertiary structure investigation for N�89 and C�274 revealed that the intrinsic fluorescence was increased and Far-UV CD spectra were changed accordingly. Relative to the wild type enzyme, 0.164, 0.195 remaining activity and lack of activity was shown with the zymographic assay for N�89, C�274 and N�89C�274 variants, respectively. The diminished enzyme activity and structural changes suggested a reorientation of microenvironments interactions including cation�� interactions around structural elements toward lowering regional mobility. Constructing applicable truncated cABC I with improved features could be regarded as a strategy to regain new possible functional advantages over the full length enzyme. © 2019, Springer Science+Business Media, LLC, part of Springer Nature