20,364 research outputs found
Association between coping strategies and drug use in a large cohort of students from a northern italian university
Background and aim of the work: Illicit drug (ID) use/abuse represent a social and economic burden for most countries worldwide which, in spite of the efforts to prevent this phenomena, is often a growing habit especially in the young adults. Preventive measurements, are needed to reduce the adverse health and social consequences of ID use/abuse. Methods: This study investigated the relationship between coping strategies and ID use in students (N=12316) from the University of Parma, Italy. Information about the ID use in the past 12 months and coping strategies were collected with a cross-sectional research design using an online questionnaire. Results: More than 25% of the participants used ID in the past year; men were more likely to use drugs than female; the likelihood of using drugs was inversely related to age. The relationship between coping strategies and ID use was analyzed with a multilevel logistic model taking into account the within-department nested structure of data. Analysis revealed that transcendence-orientation and problem-orientation were associated with a reduction of the likelihood to have used drugs. Conversely, avoidance and positive attitude were associated with an increase of the likelihood to have used drugs. Finally, seeking social support revealed a positive but modest association with increasing in drug use. Conclusions: The ID use association factors identified in this study could be utilized by the appropriate institutions/authorities as a critical review in order to develop relevant public health policies and preventive measures aimed at minimizing the use of ID in this critical age group. (www.actabiomedica.it)
Skeletal Class III Surgical-Orthodontic Treatment and Remote Digital Monitoring during COVID-19 Pandemic: A Case Report
Moderate to severe cases of skeletal Class III malocclusion, where residual growth is no longer present and an orthodontic camouflage would not achieve satisfactory outcomes, are good candidates for a combined surgical-orthodontic approach. We present the case of a 34-year-old healthy male with skeletal Class III malocclusion, where aesthetics and masticatory function were further worsened by maxillary and mandibular transverse discrepancy, hyperdivergent pattern, moderate dental crowding, occlusal contacts present only on molars, negative overjet and overbite. The management of the case included a pre-surgical phase of surgically assisted rapid palatal expansion (SARPE) and an orthodontic treatment with fixed multibracket appliance, a surgical phase consisting in Le Fort I osteotomy and bilateral sagittal split osteotomy (BSSO), and a myofunctional physical therapy targeting orofacial muscles following the orthognathic surgery. The pre-surgical phase was additionally integrated with a system of remote digital monitoring, such as Dental Monitoring®, to early detect any orthodontic emergency. As in-office visits were abruptly
interrupted because of COVID-19 pandemic, the remote digital system also permitted to regularly monitor the patient at long-distance. In conclusion, a case of skeletal Class III malocclusion was successfully managed with a multidisciplinary approach which involved orthognathic surgery, orthodontic treatment, and myofunctional physical therapy. The additional integration of remote digital technologies, such as Dental Monitoring®, may provide a continuity of care to orthodontic patients in times of COVID-19 pandemic, when the regularity of non-urgent chairside appointments might be disrupted
On Abelian Multi-Chern-Simons Field Theories
In this paper a class of multi-Chern-Simons field theories which is relevant
to the statistical mechanics of polymer systems is investigated. Motivated by
the problems which one encounters in the treatment of these theories, a general
procedure is presented to eliminate the Chern-Simons fields from their action.
In this way it has been possible to derive an expression of the partition
function of topologically linked polymers which depends explicitly on the
topological numbers and does not have intractable nonlocal terms as it happened
in previous approaches. The new formulation of multi-Chern-Simons field
theories is then used to remove and clarify some inconsistencies and
ambiguities which apparently affect field theoretical models of topologically
linked polymers. Finally, the limit of disentangled polymers is discussed.Comment: 18 pages, plain LaTe
Formation of a Matter-Wave Bright Soliton
We report the production of matter-wave solitons in an ultracold lithium 7
gas. The effective interaction between atoms in a Bose-Einstein condensate is
tuned with a Feshbach resonance from repulsive to attractive before release in
a one-dimensional optical waveguide. Propagation of the soliton without
dispersion over a macroscopic distance of 1.1 mm is observed. A simple
theoretical model explains the stability region of the soliton. These
matter-wave solitons open fascinating possibilities for future applications in
coherent atom optics, atom interferometry and atom transport.Comment: 11 pages, 5 figure
Dynamic Effect of Cold-Air Bypass Valve for Compressor Surge Recovery and Prevention in Fuel Cell Gas Turbine Hybrid Systems
A large volume between compressor and turbine is present in fuel cell gas turbine hybrid systems. The substantially larger compressor plenum volume modifies the dynamic behaviour of these systems, increasing the risk of compressor surge during transients and subsequent destruction of both turbomachinery and fuel cell components. Diverting part of the compressor inlet flow directly to the turbine inlet through a cold-air bypass valve, bypassing the fuel cell stack, has been proven to be an effective method to increase the surge margin during normal operation and also to recover the machine from fully developed surge. This study investigates the dynamic effect of different cold-air bypass valve opening/closing procedures, especially steps and ramps changing the valve fractional opening. This analysis was carried out with reference to the Hybrid Performance (Hyper) facility: a hybrid system emulated using hardware and a cyber-physical fuel cell system at the National Energy Technology Laboratory (NETL), U.S. Department of Energy (DOE). Simulations performed on a Matlab\uae-Simulink\uae dynamic model of the system based on Greitzer's theory showed a different behaviour varying the valve fractional opening with steps or ramps. Many experimental tests were performed on the Hyper facility to confirm the trends obtained from the simulations results. From the outcomes of this study, it has been possible to determine how to maximize the surge recovery effect of the cold-air bypass valve opening and to minimize surge related risks during the valve closure
Characterization of multilayer stack parameters from X-ray reflectivity data using the PPM program: measurements and comparison with TEM results
Future hard (10 -100 keV) X-ray telescopes (SIMBOL-X, Con-X, HEXIT-SAT, XEUS)
will implement focusing optics with multilayer coatings: in view of the
production of these optics we are exploring several deposition techniques for
the reflective coatings. In order to evaluate the achievable optical
performance X-Ray Reflectivity (XRR) measurements are performed, which are
powerful tools for the in-depth characterization of multilayer properties
(roughness, thickness and density distribution). An exact extraction of the
stack parameters is however difficult because the XRR scans depend on them in a
complex way. The PPM code, developed at ERSF in the past years, is able to
derive the layer-by-layer properties of multilayer structures from
semi-automatic XRR scan fittings by means of a global minimization procedure in
the parameters space. In this work we will present the PPM modeling of some
multilayer stacks (Pt/C and Ni/C) deposited by simple e-beam evaporation.
Moreover, in order to verify the predictions of PPM, the obtained results are
compared with TEM profiles taken on the same set of samples. As we will show,
PPM results are in good agreement with the TEM findings. In addition, we show
that the accurate fitting returns a physically correct evaluation of the
variation of layers thickness through the stack, whereas the thickness trend
derived from TEM profiles can be altered by the superposition of roughness
profiles in the sample image
Functional inequalities for some generalised Mehler semigroups
We consider generalised Mehler semigroups and, assuming the existence of an
associated invariant measure , we prove functional integral
inequalities with respect to , such as logarithmic Sobolev and
Poincar\'{e} type. Consequently, some integrability properties of exponential
functions with respect to are deduced
A method for estimating object detection probability, lateral resolution, and errors in 3D-LiDARs
3D-LiDARs are nowadays used for many applications, the success of which certainly depends on the processing of the LiDAR output—the point cloud, PC,—but it also inexorably depends on the quality of the PC data. In this study, we propose an experimental method aimed at allowing estimating the errors and deformations that will statistically affect the LiDAR output — the PC. Taking advantage of the fact that LiDARs sample the surrounding space by observing it along divergent lines, hereinafter referred to as rays, this study proposes a simple method based on the experimental determination of the ray detection probability — the probability that a single ray detects the hit object, or a fraction of it, by adding a point in the point cloud. All other probabilities of interest are derived from such a probability. The proposed method also allows highlighting unexpected errors such as cross-talk. As will be shown by the examples given, due to cross-talk, small objects may be deformed and enlarged on a significantly greater number of points in the PC. Likewise, objects angularly separated by an angle greater than the angular resolution declared by the manufacturer may unexpectedly result in a continuum of points. Such errors may compromise the ability to perform very important tasks such as detection, classification, and tracking of dynamic and static objects, as well as the partition of the scene into drivable and non-drivable regions and the path planning around generic obstacles in 3D space
Effect of recombinant human nerve growth factor eye drops in patients with dry eye: a phase IIa, open label, multiple-dose study
Background: Dry eye disease (DED) affects more than 14% of the elderly population causing decrease of quality of life, high costs and vision impairment. Current treatments for DED aim at lubricating and controlling inflammation of the ocular surface. Development of novel therapies targeting different pathogenic mechanisms is sought-after. The aim of this study is to evaluate safety and efficacy of recombinant human nerve growth factor (rhNGF) eye drops in patients with DED. Methods: Forty consecutive patients with moderate to severe DED were included in a phase IIa, prospective, open label, multiple-dose, clinical trial to receive rhNGF eye drops at 20 μg/mL (Group 1: G1) or at 4 μg/mL (Group 2: G2) concentrations, two times a day in both eyes for 28 days (NCT02101281). The primary outcomes measures were treatment-emerged adverse events (AE), Symptoms Assessment in Dry Eye (SANDE) scale, ocular surface staining and Schirmer test. Results: Of 40 included patients, 39 completed the trial. Both tested rhNGF eye drop concentrations were safe and well tolerated. Twenty-nine patients experienced at least one AE (14 in G1 and 15 in G2), of which 11 had at least 1 related AE (8 in G1 and 3 in G2). Both frequency and severity of DED symptoms and ocular surface damage showed significant improvement in both groups, while tear function improved only in G1. Conclusions: The data of this study indicate that rhNGF eye drops in both doses is safe and effective in improving symptoms and signs of DED. Randomised clinical trials are ongoing to confirm the therapeutic benefit of rhNGF in DED. Trial registration number: NCT02101281
Glueball operators and the microscopic approach to N=1 gauge theories
We explain how to generalize Nekrasov's microscopic approach to N=2 gauge
theories to the N=1 case, focusing on the typical example of the U(N) theory
with one adjoint chiral multiplet X and an arbitrary polynomial tree-level
superpotential Tr W(X). We provide a detailed analysis of the generalized
glueball operators and a non-perturbative discussion of the Dijkgraaf-Vafa
matrix model and of the generalized Konishi anomaly equations. We compute in
particular the non-trivial quantum corrections to the Virasoro operators and
algebra that generate these equations. We have performed explicit calculations
up to two instantons, that involve the next-to-leading order corrections in
Nekrasov's Omega-background.Comment: 38 pages, 1 figure and 1 appendix included; v2: typos and the list of
references corrected, version to appear in JHE
- …