445 research outputs found

    Bond-slip analysis via a cohesive-zone model simulating damage, friction and interlocking

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    A recently proposed cohesive-zone model which effectively combines damage, friction and mechanical interlocking has been revisited and further validated by numerically simulating the pull-out test, from a concrete block, of a ribbed steel bar in the post-yield deformation range. The simulated response is in good agreement with experimental measurements of the bond slip characteristics in the post-yield range of deformed bars reported in the literature. This study highlights the main features of the model: with physically justified and relatively simple arguments, and within the sound framework of thermodynamics with internal variables, the model effectively separates the three main sources of energy dissipation, i.e. loss of adhesion, friction along flat interfaces and mechanical interlocking. This study provides further evidence that the proposed approach allows easier and physically clearer procedures for the determination of the model parameters of such three elementary mechanical behaviours, and makes possible their interpretation and measurement as separate material property, as a viable alternative to lumping these parameters into single values of the fracture energy. In particular, the proposed approach allows to consider a single value of the adhesion energy for modes I and II

    Prostitution, Essential and Incidental Aspects: A Liberal Argument for Legalization

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    Prostituciju se često prikazuje agresivnom i prisilnom aktivnosti, pri čemu imamo uvjerljive empirijske dokaze da ponekad i jest tako. Međutim, to nije dovoljno da bi bila nezakonita. Naš je argument da bi aktivnost trebala postati nezakonita ako i samo ako je u svojoj suštini agresivna i/ili prisilna. No, prostitucija sama po sebi nije nasilna, samo incidentno. Zaista, prostitucija se može definirati kao čin pružanja, iz perspektive mušterije, ne-reproduktivnog spolnog odnosa za novac (Edlund and Korn, 2002). Ni agresija ni prisila nužno ne ulaze u ovu sveobuhvatnu definiciju. Zbog toga prostituciju treba legalizirati, a zakone koji je zabranjuju ukinuti.Prostitution is often depicted as an aggressive and coercive activity. We have convincing empirical evidence that sometimes this is indeed the case. However, this is not sufficient to make it illegal. We argue that an activity should be outlawed if and only if it is essentially aggressive and/or coercive. But prostitution is not inherently violent, only incidentally. Indeed, prostitution could be defined as “the act of rendering, from the client’s point of view, non-reproductive sex against payment” (Edlund and Korn, 2002). No aggression and/or coercion necessarily enters this all-inclusive definition. This is why prostitution should be legalized laws to the contrary repealed

    Skeletal myocyte types and vascularity in the Black Sicilian Pig.

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    The objective of this study was to verify the presence of giant fibres in the Black Sicilian pig skeletal muscle and to evaluate the effect of sex on histochemical and morphometric characteristics of the myocytes (myofibres) as well as vascularity of the muscle. Twenty Black Sicilian pigs (10 males, 10 females) from a farm in Sicily (Italy) were slaughtered at two years of age. Muscle tissues were obtained from three muscles: psoas major, longissimus dorsi, and trapezius. Myofibres were stained for myosin ATPase, succinic dehydrogenase, and α-amylase-PAS. For all fibre types, area and perimeter were measured. Slow-twitch oxidative fibres, fast-twitch glycolytic fibres and fast-twitch oxidative-glycolytic fibres were histochemically differentiated; an image-analyzing system was used. The results showed no differences between males and females in percentage of the fibre types, but there were significant differences between sexes in size of all the three fibre types. Psoas major muscle had a high percentage of slow-twitch oxidative fibres and contained more capillaries per fibre and per mm2 than trapezius and longissimus dorsi, in which fast-twitch glycolytic fibres dominated. The cross-sectional area of all fibres types was larger in longissimus dorsi than in trapezius and psoas major muscles; the giant fibres were absent in all the muscles studied. Fibre type composition may contribute to the variation of meat quality

    Autoimmune mucocutaneous blistering diseases after SARS-Cov-2 vaccination: A Case report of Pemphigus Vulgaris and a literature review

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    Background: Cases of severe autoimmune blistering diseases (AIBDs) have recently been reported in association with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination. Aims: To describe a report of oropharyngeal Pemphigus Vulgaris (OPV) triggered by the mRNABNT162b2 vaccine (Comirnaty®/ Pfizer/ BioNTech) and to analyze the clinical and immunological characteristics of the AIBDs cases reported following the SARS-CoV-2 vaccination. Methods: The clinical and immunological features of our case of OPV were documented. A review of the literature was conducted and only cases of AIBDs arising after the SARS-CoV-2 vaccination were included. Case report: A 60-year old female patients developed oropharyngeal and nasal bullous lesions seven days after the administration of a second dose of the mRNABNT162b2 vaccine (Comirnaty®/ Pfizer/BioNtech). According to the histology and direct immunofluorescence findings showing the presence of supra-basal blister and intercellular staining of IgG antibodies and the presence of a high level of anti-Dsg-3 antibodies (80 U/ml; normal < 7 U/ml) in the serum of the patients, a diagnosis of oropharyngeal Pemphigus Vulgaris was made. Review: A total of 35 AIBDs cases triggered by the SARS-CoV-2 vaccination were found (including our report). 26 (74.3%) were diagnosed as Bullous Pemphigoid, 2 (5.7%) as Linear IgA Bullous Dermatosis, 6 (17.1%) as Pemphigus Vulgaris and 1 (2.9%) as Pemphigus Foliaceus. The mean age of the sample was 72.8 years and there was a predominance of males over females (F:M=1:1.7). In 22 (62.9%) cases, the disease developed after Pfizer vaccine administration, 6 (17.1%) after Moderna, 3 (8.6%) after AstraZeneca, 3 (8.6%) after CoronaVac (one was not specified). All patients were treated with topical and/or systemic corticosteroids, with or without the addition of immunosuppressive drugs, with a good clinical response in every case. Conclusion: Clinicians should be aware of the potential, though rare, occurrence of AIBDs as a possible adverse event after the SARS-CoV-2 vaccination. However, notwithstanding, they should encourage their patients to obtain the vaccination in order to assist the public health systems to overcome the COVID-19 pandemic

    Lung ultrasound and BNP to detect hidden pulmonary congestion in euvolemic hemodialysis patients: a single centre experience

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    Background: Dry weight assessment in hemodialysis (HD) remains a challenge. The aim of the study was to investigate the prevalence of subclinical pulmonary congestion using lung ultrasound (LUS) in maintenance HD patients with no clinical or bioimpedance signs of hyperhydration. The correlation between B-lines Score (BLS) and brain natriuretic peptide (BNP) was also evaluated. Methods: Twenty-four HD patients underwent LUS and BNP dosage at the end of the mid-week HD session, monthly for 6 months. LUS was considered as positive when BLS was >15. Hospitalizations and cardiovascular events were also evaluated in relation to the BLS. Results: LUS+ patients at baseline were 16 (67%), whereas 11 (46%) showed LUS + in at least 50% of the measurements (rLUS+ patients). Only the rLUS+ patients had a higher number of cardiovascular events [p=0.019, OR: 7.4 (CI 95%. 1.32-39.8)] and hospitalizations [p=0.034, OR 5.5 (CI 95% 1.22- 24.89)]. A BNP level of 165 pg/ml was identified as cut-off value for predicting pulmonary congestion, defined by BLS >15. Conclusion: Prevalence of pulmonary congestion as assessed by LUS and persistent or recurrent BLS >15 were quite prevalent findings in euvolemic HD patients. In the patients defined as rLUS+, a higher rate of cardiovascular events and hospital admissions was registered. BNP serum levels > 165 pg/ml resulted predictive of pulmonary congestion at LUS. In the dialysis care, regular LUS examination should be reasonably included among the methods useful to detect subclinical lung congestion and to adjust patients’ dry weight

    A modular approach for remote operation of humanoid robots in search and rescue scenarios

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    In the present work we have designed and implemented a modular, robust and user-friendly Pilot Interface meant to control humanoid robots in rescue scenarios during dangerous missions. We follow the common approach where the robot is semi-autonomous and it is remotely controlled by a human operator. In our implementation, YARP is used both as a communication channel for low-level hardware components and as an interconnecting framework between control modules. The interface features the capability to receive the status of these modules continuously and request actions when required. In addition, ROS is used to retrieve data from different types of sensors and to display relevant information of the robot status such as joint positions, velocities and torques, force/torque measurements and inertial data. Furthermore the operator is immersed into a 3D reconstruction of the environment and is enabled to manipulate 3D virtual objects. The Pilot Interface allows the operator to control the robot at three different levels. The high-level control deals with human-like actions which involve the whole robot’s actuation and perception. For instance, we successfully teleoperated IIT’s COmpliant huMANoid (COMAN) platform to execute complex navigation tasks through the composition of elementary walking commands (e.g.[walk_forward, 1m]). The mid-level control generates tasks in cartesian space, based on the position and orientation of objects of interest (i.e. valve, door handle) w.r.t. a reference frame on the robot. The low level control operates in joint space and is meant as a last resort tool to perform fine adjustments (e.g. release a trapped limb). Finally, our Pilot Interface is adaptable to different tasks, strategies and pilot’s needs, thanks to a modular architecture of the system which enables to add/remove single front-end components (e.g. GUI widgets) as well as back-end control modules on the fly

    Maximizing Nash Social Welfare in 2-Value Instances: The Half-Integer Case

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    We consider the problem of maximizing the Nash social welfare when allocatinga set GG of indivisible goods to a set NN of agents. We study instances, inwhich all agents have 2-value additive valuations: The value of a good g \inG for an agent iNi \in N is either 11 or ss, where ss is an odd multiple of12\frac{1}{2} larger than one. We show that the problem is solvable inpolynomial time. Akrami et at. showed that this problem is solvable inpolynomial time if ss is integral and is NP-hard whenever s=pqs = \frac{p}{q},pNp \in \mathbb{N} and qNq\in \mathbb{N} are co-prime and p>q3p > q \ge 3. Forthe latter situation, an approximation algorithm was also given. It obtains anapproximation ratio of at most 1.03451.0345. Moreover, the problem is APX-hard,with a lower bound of 1.0000151.000015 achieved at pq=54\frac{p}{q} = \frac{5}{4}. Thecase q=2q = 2 and odd pp was left open. In the case of integral ss, the problem is separable in the sense that theoptimal allocation of the heavy goods (= value ss for some agent) isindependent of the number of light goods (= value 11 for all agents). Thisleads to an algorithm that first computes an optimal allocation of the heavygoods and then adds the light goods greedily. This separation no longer holdsfor s=32s = \frac{3}{2}; a simple example is given in the introduction. Thus analgorithm has to consider heavy and light goods together. This complicatesmatters considerably. Our algorithm is based on a collection of improvementrules that transfers any allocation into an optimal allocation and exploits aconnection to matchings with parity constraints.<br

    Maximizing Nash Social Welfare in 2-Value Instances

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    We consider the problem of maximizing the Nash social welfare when allocatinga set G\mathcal{G} of indivisible goods to a set N\mathcal{N} of agents. Westudy instances, in which all agents have 2-value additive valuations: Thevalue of every agent iNi \in \mathcal{N} for every good jGj \in \mathcal{G} isvij{p,q}v_{ij} \in \{p,q\}, for p,qNp,q \in \mathbb{N}, pqp \le q. Maybe surprisingly,we design an algorithm to compute an optimal allocation in polynomial time ifpp divides qq, i.e., when p=1p=1 and qNq \in \mathbb{N} after appropriatescaling. The problem is \classNP-hard whenever pp and qq are coprime and p3p\ge 3. In terms of approximation, we present positive and negative results forgeneral pp and qq. We show that our algorithm obtains an approximation ratioof at most 1.0345. Moreover, we prove that the problem is \classAPX-hard, witha lower bound of 1.0000151.000015 achieved at p/q=4/5p/q = 4/5.<br
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