1,500 research outputs found
Edge channel mixing induced by potential steps in an integer quantum Hall system
We investigate the coherent mixing of co-propagating edge channels in a
quantum Hall bar produced by step potentials. In the case of two edge channels
it is found that, although a single step induces only a few percent mixing, a
series of steps could yield 50% mixing. In addition, a strong mixing is found
when the potential height of a single step allows a different number of edge
channels on the two sides of the step. Charge density probability has been also
calculated even for the case where the step is smoothened.Comment: final version: 7 pages, 6 figure
Preliminary realization of an electric-powered hydraulic pump system for a waste compactor truck and a techno-economic analysis
Most industrial trucks are equipped with hydraulic systems designed for specic operations, for which the required power is supplied by the internal combustion engine (ICE). The largest share of the power consumption is required by the hydraulic system during idling operations, and, consequently, the current literature focuses on energy saving strategies for the hydraulic system rather than making the vehicle traction more efficient. This study presents the preliminary realization of an electric-powered hydraulic pump system (e-HPS) that drives the lifting of the dumpster and the garbage compaction in a waste compactor truck, rather than traditional ICE-driven hydraulic pump systems (ICE-HPSs). The different components of the e-HPS are described and the battery pack was modelled using the kinetic battery model. The end-of-life of the battery pack was determined to assess the economic feasibility of the proposed e-HPS for the truck lifespan, using numerical simulations. The aim was twofold: To provide an implementation method to retrofit the e-HPS to a conventional waste compactor truck and to assess its economic feasibility, investigating fuel savings during the use phase and the consequent reduction of CO2 emissions. Results show that the total lifespan cost saving achieved a value of 65,000. Furthermore, total CO2 emissions for the e-HPS were about 80% lower than those of the ICE-HPS, highlighting that the e-HPS can provide significant environmental benefits in an urban context
Screening and Management of Coronary Artery Disease in Kidney Transplant Candidates
Cardiovascular disease (CVD) is a major cause of morbidity and mortality in patients with chronic kidney disease (CKD), especially in end-stage renal disease (ESRD) patients and during the first year after transplantation. For these reasons, and due to the shortage of organs available for transplant, it is of utmost importance to identify patients with a good life expectancy after transplant and minimize the transplant peri-operative risk. Various conditions, such as severe pulmonary diseases, recent myocardial infarction or stroke, and severe aorto-iliac atherosclerosis, need to be ruled out before adding a patient to the transplant waiting list. The effectiveness of systematic coronary artery disease (CAD) treatment before kidney transplant is still debated, and there is no universal screening protocol, not to mention that a nontailored screening could lead to unnecessary invasive procedures and delay or exclude some patients from transplantation. Despite the different clinical guidelines on CAD screening in kidney transplant candidates that exist, up to today, there is no worldwide universal protocol. This review summarizes the key points of cardiovascular risk assessment in renal transplant candidates and faces the role of noninvasive cardiovascular imaging tools and the impact of coronary revascularization versus best medical therapy before kidney transplant on a patient’s cardiovascular outcome
Spatio-temporal analysis of the urban–rural gradient structure: an application in a Mediterranean mountainous landscape (Serra San Bruno, Italy)
Abstract. The most recent and significant transformations of European landscapes have occurred as a consequence of a series of diffused, varied and often connected phenomena: urban growth and sprawl, agricultural intensification in the most suitable areas and agricultural abandonment in marginal areas. These phenomena can affect dramatically ecosystems' structure and functioning, since certain modifications cause landscape fragmentation while others tend to increase homogeneity. Thus, a thorough comprehension of the evolution trends of landscapes, in particular those linked to urban-rural relations, is crucial for a sustainable landscape planning. In this framework, the main objectives of the present paper are: (a) to investigate Land Use/Land Cover (LULC) transformations and dynamics that occurred over the period 1955–2006 in the municipality of Serra San Bruno (Calabria, Italy), an area particularly representative of the Mediterranean mountainous landscape; (b) to compare the settlement growth with the urban planning tools in charge in the study area; (c) to examine the relationship between urban–rural gradient, landscape metrics, demographic and physical variables; (d) to investigate the evolution of urban–rural gradient composition and configuration along significant axes of landscape changes. Data with a high level of detail (minimum mapping unit 0.2 ha) were obtained through the digitisation of historical aerial photographs and digital orthophotos identifying LULC classes according to the Corine Land Cover legend. The investigated period was divided into four significant time intervals, which were specifically analysed to detect LULC changes. Differently from previous studies, in the present research the spatio-temporal analysis of urban–rural gradient was performed through three subsequent steps: (1) kernel density analysis of settlements; (2) analysis of landscape structure by means of metrics calculated using a moving window method; (3) analysis of composition and configuration of the urban–rural gradient within three landscape profiles located along significant axes of LULC change. The use of thematic overlays and transition matrices enabled a precise identification of the LULC changes that had taken place over the examined period. As a result, a detailed description and mapping of the landscape dynamics were obtained. Furthermore, landscape profiling technique, using continuous data, allowed an innovative and valuable approach for analysing and interpreting urban–rural gradient structure over space and time
Z-Drugs and their use in drug-facilitated crimes: a review of the literature
Background: Z-Drugs are a category of non-benzodiazepine sedative-hypnotic drugs that include Zolpidem, Zopiclone and Zaleplon. They are all rapidly adsorbed and have a very short half- life, features that make them first-line treatment of insomnia and, in the meantime, first-choice drugs in cases of poisoning for criminal purposes. Z-drugs are frequently use in Drug Facilitated Crime cases (DFC) and Drug Facilitated Sexual Assault (DFSA), namely crimes, robberies, extortion and sexual violence committed after administration of incapacitating substances able to induce sedative-hypnotic effects. In these circumstances, the psychoactive substance is considered as a weapon and constitutes an aggravating circumstance in the criminal act: accordingly, judicial authority legitimates the analytical determination of these substances. Currently, few tests able to detect such drugs are available in daily clinical practice. Aim: The aim of this work is to evaluate the effective utilization of Z-Drugs. Methods: We have analyzed the literature, focusing on cases in which the criminal use of such incapacitating substances has been demonstrated. Relevant scientific articles were identified from PubMed, Cochrane Central, Scopus, Web of Science, Science Direct, EMBASE up to December 2022 using the following keywords: "z-drugs", "drug facilitated crime", "forensic toxicology". The resulting references were screened to exclude duplicates. In addition, non-English papers were excluded. This evaluation left 10 articles (8 case reports and 2 original studies) divided as follows: 1 case report of a DFC (robbery), 6 cases of confirmed DFSA, 3 cases of suspected DFSA, 2 original studies about DFC. Results: The totality of the selected cases showed positive toxicological tests for a single intake of z-drugs. Conclusions: This work has shown the limitations of screening tests currently in use in the emergency rooms. Forensic toxicology tests should be introduced in daily clinical practice
Spatio-temporal analysis of the urban–rural gradient structure: an application in a Mediterranean mountainous landscape (Serra San Bruno, Italy)
The most recent and significant transformations of European landscapes have occurred as a consequence of a series of diffused, varied and often connected phenomena: urban growth and sprawl, agricultural intensification in the most suitable areas and agricultural abandonment in marginal areas. These phenomena can affect dramatically ecosystems' structure and functioning, since certain modifications cause landscape fragmentation while others tend to increase homogeneity. Thus, a thorough comprehension of the evolution trends of landscapes, in particular those linked to urban-rural relations, is crucial for a sustainable landscape planning. In this framework, the main objectives of the present paper are: (a) to investigate Land Use/Land Cover (LULC) transformations and dynamics that occurred over the period 1955–2006 in the municipality of Serra San Bruno (Calabria, Italy), an area particularly representative of the Mediterranean mountainous landscape; (b) to compare the settlement growth with the urban planning tools in charge in the study area; (c) to examine the relationship between urban–rural gradient, landscape metrics, demographic and physical variables; (d) to investigate the evolution of urban–rural gradient composition and configuration along significant axes of landscape changes. Data with a high level of detail (minimum mapping unit 0.2 ha) were obtained through the digitisation of historical aerial photographs and digital orthophotos identifying LULC classes according to the Corine Land Cover legend. The investigated period was divided into four significant time intervals, which were specifically analysed to detect LULC changes. Differently from previous studies, in the present research the spatio-temporal analysis of urban–rural gradient was performed through three subsequent steps: (1) kernel density analysis of settlements; (2) analysis of landscape structure by means of metrics calculated using a moving window method; (3) analysis of composition and configuration of the urban–rural gradient within three landscape profiles located along significant axes of LULC change. The use of thematic overlays and transition matrices enabled a precise identification of the LULC changes that had taken place over the examined period. As a result, a detailed description and mapping of the landscape dynamics were obtained. Furthermore, landscape profiling technique, using continuous data, allowed an innovative and valuable approach for analysing and interpreting urban–rural gradient structure over space and time
Embolization in Pediatric Patients: A Comprehensive Review of Indications, Procedures, and Clinical Outcomes
Embolization in pediatric patients encompasses a large spectrum of indications, ranging from the elective treatment of congenital diseases of the cardiovascular system to the urgent management of acute hemorrhagic conditions. In particular, the endovascular treatment of central and peripheral vascular malformations and hypervascular tumors represents a wide chapter for both congenital and acquired situations. Thanks to the progressive availability of low-profile endovascular devices and new embolic materials, the mini-invasive approach has gradually overtaken surgery. In this review, the main embolization procedures will be illustrated and discussed, with a focus on clinical indications and expected outcomes. The most recent mini-invasive techniques will be described, with hints on the cutting-edge devices and embolic materials
On the Rapid Collapse and Evolution of Molecular Clouds
Stars generally form faster than the ambipolar diffusion time, suggesting
that several processes short circuit the delay and promote a rapid collapse.
These processes are considered here, including turbulence compression in the
outer parts of giant molecular cloud (GMC) cores and GMC envelopes, GMC core
formation in an initially supercritical state, and compression-induced
triggering in dispersing GMC envelopes. The classical issues related to star
formation timescales are addressed: high molecular fractions, low efficiencies,
long consumption times for CO and HCN, rapid GMC core disruption and the lack
of a stable core, long absolute but short relative timescales with accelerated
star formation, and the slow motions of protostars. We consider stimuli to
collapse from changes in the density dependence of the ionization fraction, the
cosmic ray ionization rate, and various dust properties at densities above
~10^5 cm^{-3}. We favor the standard model of subcritical GMC envelops and
suggest they would be long lived if not for disruption by rapid star formation
in GMC cores. The lifecycle of GMCs is illustrated by a spiral arm section in
the Hubble Heritage image of M51, showing GMC formation, star formation, GMC
disruption with lingering triggered star formation, and envelope dispersal.
There is no delay between spiral arm dustlanes and star formation; the
classical notion results from heavy extinction in the dust lane and triggered
star formation during cloud dispersal. Differences in the IMF for the different
modes of star formation are considered.Comment: 46 pages, 5 figures, scheduled for ApJ 668, October 20, 200
Re-entrant spin susceptibility of a superconducting grain
We study the spin susceptibility chi of a small, isolated superconducting
grain. Due to the interplay between parity effects and pairing correlations,
the dependence of chi on temperature T is qualitatively different from the
standard BCS result valid in the bulk limit. If the number of electrons on the
grain is odd, chi shows a re-entrant behavior as a function of temperature.
This behavior persists even in the case of ultrasmall grains where the mean
level spacing is much larger than the BCS gap. If the number of electrons is
even, chi(T) is exponentially small at low temperatures.Comment: 9 pages, 3 figures. To be published in PR
On the L_p-solvability of higher order parabolic and elliptic systems with BMO coefficients
We prove the solvability in Sobolev spaces for both divergence and
non-divergence form higher order parabolic and elliptic systems in the whole
space, on a half space, and on a bounded domain. The leading coefficients are
assumed to be merely measurable in the time variable and have small mean
oscillations with respect to the spatial variables in small balls or cylinders.
For the proof, we develop a set of new techniques to produce mean oscillation
estimates for systems on a half space.Comment: 44 pages, introduction revised, references expanded. To appear in
Arch. Rational Mech. Ana
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