654 research outputs found
Mitigazione della suscettibilità alla liquefazione di sabbie sciolte con iniezioni di miscele plastiche: primi risultati sperimentali
Antioxidant Properties of Propofol
Propofol is an intravenous sedative-hypnotic agent indicated for induction and maintenance of general anesthesia as well as for sedation of intubated, mechanically ventilated adults in intensive care units (ICU). Propofol is characterized by a phenolic structure similar to that of a-tocopherol, and presents antioxidant properties that have been demonstrated both in vitro and in vivo. The aim of the present review is to evaluate the antioxidant properties of propofol in various models and whether or not it may be considered an efficient therapeutic tool in counteracting oxidative stress during general anesthesia and sedation in ICU
From evidence-base to practice: implementation of the Nurse Family Partnership programme in England
The aims of this article are to highlight the issues that are relevant to the implementation of a rigorously evidence-based programme of support, the Nurse Family Partnership programme, into a national system of care. Methods used are semi-structured interviews with families in receipt of the programme in the first 10 sites, with the nursing staff, with members of the central team guiding the initiative and with other professionals. Analyses of data collected during programme delivery evaluate fidelity of delivery. The results indicate that the programme is perceived in a positive light and take-up is high, with delivery close to the stated US objectives. Issues pertaining to sustainability are highlighted - in particular, local concerns about cost set against long-term rather than immediate gains. However, local investment is predominantly strong, with creative methods being planned for the future. Overall, the study shows that within an NHS system of care it is possible to deliver a targeted evidence-based programme
Efficacy of Three Different Prophylactic Treatments for Postoperative Nausea and Vomiting after Vitrectomy: A Randomized Clinical Trial
Postoperative nausea and vomiting (PONV) after vitreoretinal surgery may potentially be associated with severe complications, such as suprachoroidal hemorrhage. The purpose of the present multicenter clinical trial (NCT02386059) was to assess the efficacy of three different prophylactic treatments for PONV after vitrectomy under local anesthesia. Patients undergoing primary vitrectomy were randomized to the control arm or to one of the treatment arms (4 mg ondansetron, 4 mg dexamethasone, combination of the two drugs). The primary outcome measure was the proportion of complete response (no nausea, no vomiting, no retching, and no use of antiemetic rescue medication) during 24 h after vitrectomy. Secondary outcomes included the severity standardized score of PONV, postoperative pain standardized score, and rate of ocular and non-ocular adverse events. Baseline demographics of the 1287 patients were comparable between the four arms. The combined therapy group showed a statistically significant lower incidence of PONV compared to the placebo and monotherapy (p < 0.001). PONV severity was also reduced in the combination group compared to the others (p < 0.001). Postoperative pain scores and adverse events were comparable among the four groups. Combined therapy with dexamethasone and ondansetron was the most effective treatment for reducing the incidence and severity of PONV in patients undergoing vitrectomy under local anesthesia
BIO-INDUCED PARTIAL SATURATION AS A LIQUEFACTION MITIGATION TECHNIQUE
The present work aims to the development of a bio-Induced Partial Saturation (bio IPS) technique able to generate gas bubbles within the pores of the soil and, at the same time, to the development of a reliable monitoring technique. Starting from the identification and isolation of specific microorganisms able to generate gas bubbles, the work aims first at evaluating the capability of the selected microorganisms to nucleate bubbles. Then, the environmental compatibility of the metabolism's products is investigated by performing preliminary chemical and biological tests, in order to verify the applicability of the technique.
Successively, with the aim to quantify the amount of generated gas, desaturation tests are carried out for different experimental conditions, monitoring at the same time environmental parameters of interest as well. Once the nucleation process has been widely explored, and the environmental compatibility has been ensured, the experimental setup has been finally focused on possible monitoring techniques able to control and verify the degrees of saturation achieved with the IPS technology. Basically, two possible monitoring parameters have been investigated, i.e. electrical resistivity and P-waves velocity. Their sensitivity to the degree of saturation of a soil will be analysed in detail as it follows, showing that such parameters are well suited to quantify the desaturation level achieved with the bio-IPS technique and, on the other hand, that a delicate interpretation of the data must to be taken into account. It will be highlighted that a combination of the two technologies is likely the best possible monitoring solution
Observation of low energy dispersive modes in un- derdoped (La, Nd) 2−x Sr x CuO 4
We find excitations lower in energy than known phonon modes in underdoped LaSrCuO (x=0.08), with both inelastic X-Ray scattering (IXS) and inelastic neutron scattering (INS). A non dispersive excitation at 9 meV is identified and is also seen by INS in (La,Nd)SrCuO, with 40 Nd substitution. INS also identifies a still lower energy dispersive mode at low q in the Nd free sample. These modes are clearly distinct from the longitudinal acoustic phonon and correspond in energy to the Zone Centre modes measured by optical spectroscopy and associated with stripe dynamics
Multiscale Modeling with Differential Equations
Many physical systems are governed by ordinary or partial differential
equations (see, for example, Chapter ''Differential equations'', ''System of
Differential Equations''). Typically the solution of such systems are functions
of time or of a single space variable (in the case of ODE's), or they depend on
multidimensional space coordinates or on space and time (in the case of PDE's).
In some cases, the solutions may depend on several time or space scales. An
example governed by ODE's is the damped harmonic oscillator, in the two extreme
cases of very small or very large damping, the cardiovascular system, where the
thickness of the arteries and veins varies from centimeters to microns, shallow
water equations, which are valid when water depth is small compared to typical
wavelength of surface waves, and sorption kinetics, in which the range of
interaction of a surfactant with an air bubble is much smaller than the size of
the bubble itself. In all such cases a detailed simulation of the models which
resolves all space or time scales is often inefficient or intractable, and
usually even unnecessary to provide a reasonable description of the behavior of
the system. In the Chapter ''Multiscale modeling with differential equations''
we present examples of systems described by ODE's and PDE's which are
intrinsically multiscale, and illustrate how suitable modeling provide an
effective way to capture the essential behavior of the solutions of such
systems without resolving the small scales.Comment: 40 pages, 20 figures, to be published as a book chapter in a SIAM
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A finite-difference ghost-point multigrid method for multi-scale modelling of sorption kinetics of a surfactant past an oscillating bubble
We propose a method for the numerical solution of a multiscale model
describing sorption kinetics of a surfactant around an oscillating bubble. The
evolution of the particles is governed by a convection-diffusion equation for
the surfactant concentration , with suitable boundary condition on the
bubble surface, which models the action of the short range attractive-repulsive
potential acting on them when they get sufficiently close to the surface
\cite{multiscale_mod}. In the domain occupied by the fluid, the particles are
transported by the fluid motion generated by the bubble oscillations. The
method adopted to solve the equation for is based on a finite-difference
scheme on a uniform Cartesian grid and implemented in 2D and 3D axisymmetric
domains. We use a level-set function to define the region occupied by the
bubble, while the boundary conditions are discretized by a ghost-point
technique to guarantee second order accuracy at the curved boundary. The sparse
linear system is finally solved with a geometric multigrid technique designed
\textit{ad-hoc\/} for this specific problem. Several accuracy tests are
provided to prove second order accuracy in space and time.
The fluid dynamics generated by the oscillating bubble is governed by the
Stokes equation solved with a second order accurate method based on a
monolithic approach, where the momentum and continuity equations are solved
simultaneously. Since the amplitude of the bubble oscillations are very small,
a simplified model is presented where the computational bubble is actually
steady and its oscillations are represented purely with time-dependent boundary
conditions. A numerical comparison with the moving domain model confirms that
this simplification is perfectly reasonable for the class of problems
investigated in this paper
Finite element discretization of a biological network formation system: a preliminary study
A finite element discretization is developed for the Cai-Hu model, describing
the formation of biological networks. The model consists of a non linear
elliptic equation for the pressure and a non linear reaction-diffusion
equation for the conductivity tensor . The problem requires high
resolution due to the presence of multiple scales, the stiffness in all its
components and the non linearities. We propose a low order finite element
discretization in space coupled with a semi-implicit time advancing scheme. The
code is {verified} with several numerical tests performed with various choices
for the parameters involved in the system. In absence of the exact solution, we
apply Richardson extrapolation technique to estimate the order of the method.Comment: 11 pages, 3 figures, 18 plots, 2 table
Serving highly vulnerable families in home-visitation programs
Home-visitation programs for families with young children are growing in popularity in the US. These programs typically seek to prevent child abuse and neglect and/or promote optimal development for infants, toddlers, and/or preschool-age children. This paper focuses on improving the capacity of home-visitation programs to meet the complex needs of highly vulnerable families with young children. Poverty, maternal depression and substance abuse, and domestic violence are noted as factors that place young children at risk for poor outcomes. The challenges of providing home-visitation services to families in which these risk factors are present are discussed. Family engagement, matching services to families’ needs, and staff capabilities are highlighted as areas in which improvements can be made to enhance home-visitation programs’ capacity to serve highly vulnerable families. Recommendations are given for improving the effectiveness of home-visitation programs in serving these families, as well for addressing policy and research issues related to the further development and evaluation of these programs.First author draf
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