323,815 research outputs found
Reply to Michael A. Gorin, Arthur I. Sagalowsky and Mark S. Soloway's Letter to the Editor re: S. Picozzi, C. Ricci, M. Gaeta et al. Upper urinary tract recurrence following radical cystectomy for bladder cancer: a meta-analysis on 13,185 patients. J Urol 2012; 188: 2046-54
No full textCharge-density waves, quantum-anharmonicity, polar responses and resonant Raman in 1D conjugated systems
No full textSystems with reduced dimensionality are known to display many fascinating phenomena, with properties often showing pathological behaviors. In this context, one of the most studied aspect regards the insurgence of a modulation of the electronic charge density, i.e. a charge density wave (CDW). The interest in CDWs physics is very broad as they are present in many systems, ranging from 1D and 2D materials, to high Tc superconductors and transition metal dichalcogenides. CDWs usually manifest as a broken-symmetry state, that in 1D chains of atoms results in the presence of a bond-length alternation, commonly explained as a consequence of the interplay between an instability of electronic origin and the coupling between electronic and lattice degrees of freedom. It is commonly understood that the interplay of these elements in 1D systems regulates the competition between a dimerized, less symmetric, configuration and an undimerized, more symmetric, one. In particular, a diatomic chain of atoms presents a second-order phase transition between these two phases. However, a part for these two ingredients, many other different elements are actually at play in the creation of a CDW. Indeed, there are evidences that the presence of a CDW in the infinitely-long straight chains of carbon atoms, called carbyne, is strongly affected by quantum and anharmonic fluctuations, as well as from the effect of an external environment, as we confirm and discuss in our study. The aim of the present work is thus, on one hand, to unveil the contribution of each element to the manifestation of a CDW, and, on the other hand, to study the properties of 1D systems that host CDWs. Indeed, the instability at the boundaries of the structural phase transition suggests the presence of interesting and peculiar polar responses. Following this idea, in our work, we show how 1D systems such as conjugated polymers present a huge enhancement of the effective charges, with values up to 30 times that of the nominal electronic charge at the critical point of the transition, and of the piezoelectric coefficients, which in principle present a diverging behavior in proximity of the phase boundary. In the task of determining the properties of these materials, it is then fundamental to resort to particular experimental techniques, such as resonance Raman spectroscopy. However, at date, a theory which permits to accurately describe experimental results on 1D systems is lacking. We address this problem in our work, introducing a framework that allows for the calculation of resonance Raman spectra beyond the commonly adopted Placzek approximation, even in systems beyond the simple 1D case
Legal accountability in Clinical Ethics Consultation
No full textThe aim of this paper is to outline the framework for a critical reflection about legal accountability associated with Clinical Ethics Consultation (CEC). First of all, we will explain why we believe that, at the present time, in Italy, CEC provided by an individual Ethics Consultant shoud be considered the best format to guarantee a quality service to patients and healthcare professionals. We will then analyse whether and when an Ethics Consultant can be held liable for violation of a civil or criminal law. Finally, starting from the analysis of the jurisprudential evolution and the healthcare legislation reforms, we will propose a discipline applicable to the Ethics Consultant's activity in case of damage to a patient. According to this perspective, we will illustrate why the formal and juridical acknowledgement of the Ethics Consultant's activity can define the contents of his actual role in the care process while helping to spread the CEC culture as a dialogic process meant to effectively improve health care through the identification, analysis and resolution of ethical dilemmas in clinical practice
Is Left Ventricular Assist Device Deactivation Ethically Acceptable? A Study on the Euthanasia Debate
No full textIn the last decades, new technologies have improved the survival of patients affected by chronic illnesses. Among them, left ventricular assist device (LVAD) has represented a viable solution for patients with advanced heart failure (HF). Even though the LVAD prolongs life expectancy, patients' vulnerability generally increases during follow up and patients' request for the device withdrawal might occur. Such a request raises some ethical concerns in that it directly hastens the patient's death. Hence, in order to assess the ethical acceptability of LVAD withdrawal, we analyse and examine an ethical argument, widely adopted in the literature, that we call the "descriptive approach", which consists in giving a definition of life-sustaining treatment to evaluate the ethical acceptability of treatment withdrawal. Focusing attention on LVAD, we show criticisms of this perspective. Finally, we assess every patient's request of LVAD withdrawal through a prescriptive approach, which finds its roots in the criterion of proportionality
A trade-investment model for distribution of wealth
No full textEconophysics provides a strategy for understanding the potential mechanisms underlying the anomalous distribution of wealth found in real societies. We present a computational nonlinear stochastic model for the distribution of wealth that depends upon three parameters and two mechanisms: trade and investment. To avoid economic paradoxes, the trade mechanism is assumed to be related to the poorer trader???s wealth and to statistically advantage the poorer of the two traders. The two mechanisms together are shown to generate a distribution that reproduces the full range of the empirical wealth distribution, and not only the inverse power-law tail that Pareto found in western societies at the end of the 19th century
Re: the results of ureteral stenting after ureteroscopic lithotripsy for ureteral calculi: a systematic review and meta-analysis: S. Pengfei, L. Yutao, Y. Jie, W. Wuran, D. Yi, Z. Hao and W. Jia, J Urol 2011; 186: 1904-1909
No full textShallow geology characterization using Rayleigh and Love wave dispersion curves derived from seismic noise array measurements
No full textRole of structural defects on the half-metallic character of Co2MnGe and Co2MnSi Heusler alloys
No full textHeusler alloys, such as Co2MnSi and Co2MnGe, have been predicted from first–principles to be half metallic and potential candidates for spintronic applications. However, spin polarizations of only 50–60% were experimentally obtained for these compounds—a decrease attributed to defects in the Mn and Co sub- lattices. Accurate ab initio full-potential linearized augmented plane wave calculations are performed in order to determine the effects of several types of defects such as antisites and atomic swaps on the electronic and magnetic properties of the bulk Heusler compounds. Our findings, in general agreement with experiments, show that Mn antisites have the lowest formation energy and retain the half-metallic character. On the other hand, Co antisites have a slightly higher formation energy and a dramatic effect on the electronic properties: the defect states that locally destroy half metallicity are energetically localized and are screened out in a couple of atomic shells. In this case, the spin polarization at the Fermi level is strongly reduced, and the spin polarization due to the s electrons, responsible for the tunneling current, is in excellent agreement with experiment. Finally, both Mn-Si and Mn-Co atomic swaps have very high formation energies, keeping however the half-metallic character
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