Abstract Objectives In this study, the authors analyzed the prognostic role of right ventricular systolic function (RVF) longitudinal trends in a large cohort of patients affected by dilated ...cardiomyopathy (DCM). Background RVF is a known prognostic predictor in DCM; however, whether RVF changes over time to better predict the long-term disease progression has not been investigated. Methods From 1993 to 2008, we analyzed 512 patients with DCM (46 years of age 36 to 55 years of age, left ventricular ejection fraction 32% 25% to 41%) with a potential follow-up of ≥72 months and available data at baseline and at least 1 pre-specified follow-up evaluation (i.e., 6, 24, 48, or 72 months). RV dysfunction was defined as RV fractional area change <35% at 2-dimensional echocardiography. The primary outcome measure was a composite of death or heart transplantation. Results At enrollment, 103 (20%) patients had RV dysfunction. During follow-up, 89 of them (86%, 17% of the overall cohort) normalized RVF at a median time of 6 months, whereas 38 of the remaining 409 patients with normal baseline RVF (9%; 7% of the overall population) exhibited a new-onset RV dysfunction (median time: 36 months). RVF normalization was significantly associated with subsequent left ventricular reverse remodeling that was observed at a median time of 24 months (odds ratio: 2.49; 95% confidence interval CI: 1.17 to 5.3; p = 0.018). At baseline multivariate analysis, RV dysfunction was independently associated with the primary outcome measure (hazard ratio: 1.71; 95% CI: 1.02 to 2.85; p = 0.0413). At time-dependent model, RVF revaluation over time maintained an independent predictive value (hazard ratio: 2.83; 95% CI: 1.57 to 5.11; p = 0.0006). Conclusions Patients with DCM frequently present RV dysfunction at first evaluation. However, a complete RVF recovery is largely observed early after optimization of medical therapy and predates subsequent left ventricular reverse remodeling. Systematic revaluation of patients including RVF throughout regular follow-up conferred additive long-term prognostic value to the baseline evaluation.
The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has consistently changed medical practice throughout specialties, regardless of their contribution in facing the disease ...itself. We surveyed neurosurgeons worldwide to investigate the situation they are experiencing.
A 17-question, web-based survey was administered to neurosurgeons worldwide through the World Federation of Neurosurgical Societies and the Neurosurgery Cocktail from March 28 to April 5, 2020, by web link or e-mail invitation. Questions were divided into 3 subgroups: general information, health system organization, and institutional plans for the SARS-CoV-2 outbreak. Collected data were initially elaborated using SurveyMonkey software. Country-specific data were extracted from the World Health Organization website. Statistical analysis was performed using R, version 3.6.3.
Of the 446 respondents, most were from Italy (20%), India (19%), and Pakistan (5%). Surgical activity was significantly reduced in most centers (79%) and dedicated in-hospital routes were created for patients with SARS-CoV-2 (58%). Patient screening was performed only when there were symptoms (57%) and not routinely before surgery (18%). The preferred methods included a nasopharyngeal swab and chest radiograph. Health professionals were rarely screened (20%) and sometimes, even if SARS-CoV-2 positive, were asked to work if asymptomatic (26%). Surgical planning was changed in most institutions (92%), whereas indications were modified for nonurgent procedures (59%) and remained unchanged for subarachnoid hemorrhages (85%).
Most neurosurgeons worldwide reported work reorganization and practices that respond to current international guidelines. Differences in practice might be related to the perception of the pandemic and significant differences in the health systems. Sharing data and experiences will be of paramount importance to address the present moment and challenges in the near future.
Firstly formulated to solve unconstrained optimization problems, the common way to solve constrained ones with the metaheuristic particle swarm optimization algorithm (PSO) is represented by adopting ...some penalty functions. In this paper, a new nonpenalty-based constraint handling approach for PSO is implemented, adopting a supervised classification machine learning method, the support vector machine (SVM). Because of its generality, constraint handling with SVM appears more adaptive both to nonlinear and discontinuous boundary. To preserve the feasibility of the population, a simple bisection algorithm is also implemented. To improve the search performances of the algorithm, a relaxation function of the constraints is also adopted. In the end part of this paper, two numerical literature benchmark examples and two structural examples are discussed. The first structural example refers to a homogeneous constant cross-section simply supported beam. The second one refers to the optimization of a plane simply supported Warren truss beam. The obtained results in terms of objective function demonstrate that this new approach represents a valid alternative to solve constrained optimization problems even in structural optimization field. Furthermore, as demonstrated by the Warren truss beam problem, this new algorithm provides an optimal structural design which represents also a good solution from the technical point of view with a trivial rounding-off that does not jeopardize significantly the optimization design process.
We performed a suite of experiments aimed at examining the frictional properties of unaltered basalts at conditions considered to be representative of slip at shallow depths in volcano-tectonic ...environments and in-situ geo-energy basaltic sites. Scientific drilling and field studies on exhumed subsurface faults and fractures analogues suggest that, frictional sliding in basalts can occur in shear zones within a volume of wear debris or along localized joint surfaces. To illuminate how microstructural heterogeneities affect the nucleation of slip instabilities in basalts, we sheared simulated fault gouge and bare rock surfaces at low normal stresses (4–30 MPa) at ambient temperature, under room-dry and wet conditions. We performed velocity steps (0.1–300 μm/s) and slide-hold-slides (30–3000 s holds) to determine the frictional stability and healing properties of basalts. In all the tests, we observed high friction coefficient associated with important frictional restrengthening. Overall, our results show that microstructural heterogeneities strongly affect the friction velocity dependence of basalts: while for normal stresses ≥10 MPa, shear localization accompanied by cataclasis and grain size reduction favors the transition to velocity weakening behavior of powdered samples, on bare surfaces gouge production during shearing promotes a transition to a velocity strengthening behavior. Our results imply that at the tested conditions, friction instabilities may promptly nucleate in shear zones where deformation within (unaltered) basaltic gouge layers is localized, such as those located along volcanic flanks, while joint surfaces characterized by rough rock-on-rock contacts are less prone to unstable slip, which is suppressed at velocities ≥10 μm/s.
•Unaltered basalt faults are frictionally strong with high healing rates.•Basalt microstructural heterogeneities affect the stability of sliding.•Fault gouges may nucleate slip instabilities.•Bare rock surfaces are less prone to unstable slip.
This paper addresses a collective motion problem for a multi-agent system composed of nonholonomic vehicles. The aim of the vehicles is to achieve circular motion around a virtual reference beacon. A ...control law is proposed, which guarantees global asymptotic stability of the circular motion with a prescribed direction of rotation, in the case of a single vehicle. Equilibrium configurations of the multi-vehicle system are studied and sufficient conditions for their local stability are given, in terms of the control law design parameters. Practical issues related to sensory limitations are taken into account. The transient behavior of the multi-vehicle system is analyzed via numerical simulations.
Assessing temporal changes in species extinction risk is necessary for measuring conservation success or failure and for directing conservation resources toward species or regions that would benefit ...most. Yet, there is no long‐term picture of genuine change that allows one to associate species extinction risk trends with drivers of change or conservation actions. Through a review of 40 years of IUCN‐related literature sources on species conservation status (e.g., action plans, red‐data books), we assigned retrospective red‐list categories to the world's carnivores and ungulates (2 groups with relatively long generation times) to examine how their extinction risk has changed since the 1970s. We then aggregated species’ categories to calculate a global trend in their extinction risk over time. A decline in the conservation status of carnivores and ungulates was underway 40 years ago and has since accelerated. One quarter of all species (n = 498) moved one or more categories closer to extinction globally, while almost half of the species moved closer to extinction in Southeast Asia. The conservation status of some species improved (toward less threatened categories), but for each species that improved in status 8 deteriorated. The status of large‐bodied species, particularly those above 100 kg (including many iconic taxa), deteriorated significantly more than small‐bodied species (below 10 kg). The trends we found are likely related to geopolitical events (such as the collapse of Soviet Union), international regulations (such as CITES), shifting cultural values, and natural resource exploitation (e.g., in Southeast Asia). Retrospective assessments of global species extinction risk reduce the risk of a shifting baseline syndrome, which can affect decisions on the desirable conservation status of species. Such assessments can help conservationists identify which conservation policies and strategies are or are not helping safeguard biodiversity and thus can improve future strategies. Una Evaluación Retrospectiva de la Declinación Global de Carnívoros y Ungulados
The aim of this work is to investigate the long-term bleeding risk of cerebral cavernous malformation (CCM) remnants. A review of clinical, radiological, operative, and post-operative data of a ...cerebral cavernous malformation (CCMs) prospective database was performed. Fisher’s exact test and Mann-Whitney
U
-test were used to assess differences between non-hemorrhagic and hemorrhagic CCM remnants for 14 variables. Recursive partitioning analysis was performed to assess the order of variables most associated with CCM remnant bleeding. Twenty-four patients out of 126 had a CCM post-surgical remnant. Of these, 7 had at least one post-operative hemorrhagic event. The mean follow-up was 80.7 months (range 12–144). CCM post-surgical remnant bleeding presented mostly with acute headache (50%) and focal neurological deficit (25%); in the remaining cases, the hemorrhage was asymptomatic. Retreatment was performed in two patients, with surgery and radiosurgery, respectively; no treatment was performed in the majority of cases. All patients ranked as non-II, according to Zabramski classification, did not show any post-surgical bleeding. The presence of a pre-operative perilesional hemosiderin ring was highly significant in predicting post-surgical bleeding (sensitivity = 0.94, specificity = 0.88) and incorrectly predicted bleeding in only two of the 24 patients. This study provides an evaluation of clinical and radiological factors influencing the bleeding risk of a CCM post-surgical remnant in a homogeneous population. Perilesional hemosiderin ring and Zabramski Type II appear to strongly condition the bleeding risk of a CCM post-surgical remnant.
Mast cells are abundant in the heart, among myocardial fibers, around coronary arteries, within arterial intima and intramural vessels, and in atherosclerotic plaques. Their mediators can be released ...during anaphylaxis and be responsible for acute coronary syndrome. This condition has been described as Kounis syndrome (KS). We report three cases of acute myocardial ischemia, which fulfill the definition for KS. In Cases 1 and 2, the association of intense chest pain with acute urticaria after an allergenic contact (wasp sting and betalactam antibiotic administration, respectively) was suspected to be an attack of angina related to an allergic reaction. No signs of an allergic reaction were observed in Case 3, but only the history of a wasp sting suggested its relationship to loss of consciousness and heart ischemia when hypersensitivity to venom was ascertained. These cases strongly recommend measurement of anaphylactic biomarkers, such as tryptase, during acute coronary syndromes to detect the possible involvement of an allergic reaction. Conversely, measurement of cardiac biomarkers during anaphylaxis, even without obvious signs of myocardial ischemia, might identify patients at risk of myocardial injury.
This comment shows that Peng (2018)’s Theorem 2 requires amendment. A new set of (relatively stricter) assumptions is provided, under which Peng (2018)’s findings –in particular, the asymmetric ...impact of capital and income risk on wealth mobility –hold true, and the approach developed therein proves suited for comparing stationary distributions of linear stochastic models.
•Peng (2018)’s Theorem 2 requires amendment.•An alternative set of assumptions is provided to support Peng (2018)’s claims.•Income tax has no impact on wealth mobility.•A tax on capital returns increases wealth mobility.
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