450 research outputs found
Bulk Mediated Surface Diffusion: Non Markovian Desorption with Finite First Moment
Here we address a fundamental issue in surface physics: the dynamics of
adsorbed molecules. We study this problem when the particle's desorption is
characterized by a non Markovian process, while the particle's adsorption and
its motion in the bulk are governed by a Markovian dynamics. We study the
diffusion of particles in a semi-infinite cubic lattice, and focus on the
effective diffusion process at the interface . We calculate analytically
the conditional probability to find the particle on the plane as well as
the surface dispersion as functions of time. The comparison of these results
with Monte Carlo simulations show an excellent agreement.Comment: 16 pages, 7 figs. European Physical Journal B (in press
A systemic design application for resources management in urban green spaces
Urban green spaces are often analyzed by the quantity of provided services, the kind of benefits they supply for the community and the human actions that modify the urban ecosystems. Moreover, urban green spaces and green infrastructures can produce important resources, even if these latter are not always considered during the preparation of management plans. To this extent, the Systemic Design can help to show the qualitative aspects of these resources and how they can be managed. Aim of this study is therefore to illustrate how a holistic approach like the Systemic Design can be applied to the management of urban green infrastructure, their ecosystem services and the raw materials and resources useful for the community.With an application to a real case, we will show how a Systemic Design approach is able to state resources' availability in a green urban area with the consequent identification of the area in which these resources can be employed. This identification is the essential prerequisite for the creation of a plan that stress the links among ecosystem services, resources and urban dwellers and the consequent best management practices, with particular emphasis on challenges related to climate changes and increasing urbanization.When necessary, Systemic Design can also provide viable indications to redesign a new context with different fluxes of materials and energy and can contribute to the creation of a set of new activities deeply connected with local green spaces. The final results can be identified in the creation of work tools for administrators and urban designers interested in the integrated management of green infrastructures and the suggestion of a new urban model, with stronger connections between society and territory, for more sustainable and resilient cities
Probabilistic cost-effectiveness analysis of controlled ovarian stimulation with recombinant FSH plus recombinant LH vs. human menopausal gonadotropin for women undergoing IVF
Background
The association of recombinant FSH plus recombinant LH in 2:1 ratio may be used not only to induce ovulation in anovulatory women with hypogonadotropic hypogonadism but also to achieve multiple follicular developments in human IVF. The aim of this analysis was to estimate the cost-effectiveness of Controlled Ovarian Stimulation (COS) with recombinant FSH (rFSH) plus recombinant LH (rLH) in comparison with highly purified human menopausal gonadotropin (HP-hMG) in the woman undergoing in vitro fertilization (IVF) in Italy.
Methods
A probabilistic decision tree was developed to simulate patients undergoing IVF, either using r-FSH + r-LH or HP-hMG to obtain COS. The model considers the National Health System (NHS) perspective and a time horizon equal to two years. Simulations were reported considering the number of retrieved oocytes (5–9, 10–15 and > 15) and transition probabilities were estimated through specific analyses carried out on the population of 848 women enrolled in the real-life.
Results
The model estimated that patients undertaking therapeutic protocol with r-FSH + r-LH increase the general success rate (+ 6.6% for pregnancy). The incremental cost-effectiveness ratio (ICER) per quality-adjusted life year (QALY) of r-FSH + r-LH was below the willingness to pay set at €20,000 for all the considered scenarios.
Conclusions
The cost-utility analysis demonstrated that the r-FSH + r-LH is a cost-effective option for the Italian National Health System (NHS)
Discretization-related issues in the KPZ equation: Consistency, Galilean-invariance violation, and fluctuation--dissipation relation
In order to perform numerical simulations of the KPZ equation, in any
dimensionality, a spatial discretization scheme must be prescribed. The known
fact that the KPZ equation can be obtained as a result of a Hopf--Cole
transformation applied to a diffusion equation (with \emph{multiplicative}
noise) is shown here to strongly restrict the arbitrariness in the choice of
spatial discretization schemes. On one hand, the discretization prescriptions
for the Laplacian and the nonlinear (KPZ) term cannot be independently chosen.
On the other hand, since the discretization is an operation performed on
\emph{space} and the Hopf--Cole transformation is \emph{local} both in space
and time, the former should be the same regardless of the field to which it is
applied. It is shown that whereas some discretization schemes pass both
consistency tests, known examples in the literature do not. The requirement of
consistency for the discretization of Lyapunov functionals is argued to be a
natural and safe starting point in choosing spatial discretization schemes. We
also analyze the relation between real-space and pseudo-spectral discrete
representations. In addition we discuss the relevance of the Galilean
invariance violation in these consistent discretization schemes, and the
alleged conflict of standard discretization with the fluctuation--dissipation
theorem, peculiar of 1D.Comment: RevTex, 23pgs, 2 figures, submitted to Phys. Rev.
Age-related increase in resistance to acute Trypanosoma cruzi infection in rats is associated with an appropriate antibody response
Inoculation at weaning with Trypanosoma cruzi in inbred 'l' rats resulted in a self-resolving acute infection characterized by marked parasitaemias, whereas challenge to adult rats revealed a mild disease with extremely low parasitaemias. To explore the mechanisms underlying such age-associated differences in disease outcome, we analysed the in vitro replication of T. cruzi, nitric oxide and tumour necrosis factor-α (TNF-α) production in peritoneal macrophages (PMs), the serum concentrations of the specific immunoglobulins (Igs) IgM and IgG, antibodies exhibiting lytic activity against bloodstream forms of T. cruzi and circulating levels of nitrate, TNF-α and interferon-Îł (IFN-Îł). Macrophages from young rats were as effective as their adult counterparts for restraining intracellular parasite replication. When stimulated with IFN-Îł, culture supernatants from young PMs contained higher amounts of nitrite and TNF-α. Serum samples from 4 and 7 days post infection revealed easily detectable amounts of nitrate, with values being further augmented by day 7 post infection and significantly higher in the young group. TNF-α levels were only detected in the young group by day 7 post infection. Both groups had increased amounts of IFN-Îł in their sera, although in adult rats, this trend was followed by a significant drop at day 7, with young rats showing values still higher by the same time point evaluation. In contrast, young rats presented significantly lower levels of IgM and IgG antibodies during the first week of infection. Increased resistance in adult rats seems to be the result of a more appropriate antibody production.Fil: Pascutti, MarĂa Fernanda. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Rosario. Instituto de InmunologĂa Clinica y Experimental de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias MĂ©dicas. Instituto de InmunologĂa Clinica y Experimental de Rosario; ArgentinaFil: Bottasso, Oscar Adelmo. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Rosario. Instituto de InmunologĂa Clinica y Experimental de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias MĂ©dicas. Instituto de InmunologĂa Clinica y Experimental de Rosario; ArgentinaFil: Hourquescos, M. C.. Universidad Nacional de Rosario; ArgentinaFil: Wietzerbin, Jeanne. Institute Curie; FranciaFil: Revelli, Silvia Susana. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Rosario. Instituto de InmunologĂa Clinica y Experimental de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias MĂ©dicas. Instituto de InmunologĂa Clinica y Experimental de Rosario; Argentin
The weight of water
Leonardo da Vinci’s pioneering work on hydrostatics combined traditional knowledge and innovative empiricism in an attempt to understand an object fraught with paradox: the water-filled container
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