8,127 research outputs found
L.A.U.D.E: Learning Automata for Urban Development Exploration. The Case Study of Rome Urban System
This paper deals with urban cellular automata. It is organized in two parts. The first one is concerning theory, methodology and operational aspects of the application of cellular automata to the simulation of dynamics of urban systems. Starting with a review of the literature on this research field (Batty, Cecchini, Couclelis, White et al.) we present: ? as to theoretical foundation of the approach, a clarification on the distinction between global and local description (the traditional modelling and cellular automata, respectively); ? as to methodology, an analysis of different ways of association of cellular automata to urban phenomena (cells as individuals, cells as "spatial zones" of the city, etc.); ? as to operational problems, a discussion - among other things - of the treatment of distances, size and shape of cells, random effects, dynamics ... . Second part of the paper is more specifically concerning with identification of the transition rules controlling the temporal evolution of cellular automata. We present: ? the general theory of identification (and calibration) of cellular automata; ? a short recall to "cellular automata with endogenous identification" (i.e. learning automata) developed by two of the authors (Papini and Rabino, 1996); ? an extended report on the application of these learning automata to the explanation of the development of a territorial system (i.e. an experimental case-study)
Not All Children with Cystic Fibrosis Have Abnormal Esophageal Neutralization during Chemical Clearance of Acid Reflux.
PurposeAcid neutralization during chemical clearance is significantly prolonged in children with cystic fibrosis, compared to symptomatic children without cystic fibrosis. The absence of available reference values impeded identification of abnormal findings within individual patients with and without cystic fibrosis. The present study aimed to test the hypothesis that significantly more children with cystic fibrosis have acid neutralization durations during chemical clearance that fall outside the physiological range.MethodsPublished reference value for acid neutralization duration during chemical clearance (determined using combined impedance/pH monitoring) was used to assess esophageal acid neutralization efficiency during chemical clearance in 16 children with cystic fibrosis (3 to <18 years) and 16 age-matched children without cystic fibrosis.ResultsDuration of acid neutralization during chemical clearance exceeded the upper end of the physiological range in 9 of 16 (56.3%) children with and in 3 of 16 (18.8%) children without cystic fibrosis (p=0.0412). The likelihood ratio for duration indicated that children with cystic fibrosis are 2.1-times more likely to have abnormal acid neutralization during chemical clearance, and children with abnormal acid neutralization during chemical clearance are 1.5-times more likely to have cystic fibrosis.ConclusionSignificantly more (but not all) children with cystic fibrosis have abnormally prolonged esophageal clearance of acid. Children with cystic fibrosis are more likely to have abnormal acid neutralization during chemical clearance. Additional studies involving larger sample sizes are needed to address the importance of genotype, esophageal motility, composition and volume of saliva, and gastric acidity on acid neutralization efficiency in cystic fibrosis children
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Membrane Scaffolds Enhance the Responsiveness and Stability of DNA-Based Sensing Circuits.
Target-induced DNA strand displacement is an excellent candidate for developing analyte-responsive DNA circuitry to be used in clinical diagnostics and synthetic biology. While most available technologies rely on DNA circuitry free to diffuse in bulk, here we explore the use of liposomes as scaffolds for DNA-based sensing nanodevices. Our proof-of-concept sensing circuit responds to the presence of a model target analyte by releasing a DNA strand, which in turn activates a fluorescent reporter. Through a combination of experiments and coarse-grained Monte Carlo simulations, we demonstrate that the presence of the membrane scaffold accelerates the process of oligonucleotide release and suppresses undesired leakage reactions, making the sensor both more responsive and robust
Flexibility defines structure in crystals of amphiphilic DNA nanostars.
DNA nanostructures with programmable shape and interactions can be used as building blocks for the self-assembly of crystalline materials with prescribed nanoscale features, holding a vast technological potential. Structural rigidity and bond directionality have been recognised as key design features for DNA motifs to sustain long-range order in 3D, but the practical challenges associated with prescribing building-block geometry with sufficient accuracy have limited the variety of available designs. We have recently introduced a novel platform for the one-pot preparation of crystalline DNA frameworks supported by a combination of Watson-Crick base pairing and hydrophobic forces (Brady et al 2017 Nano Lett. 17 3276-81). Here we use small angle x-ray scattering and coarse-grained molecular simulations to demonstrate that, as opposed to available all-DNA approaches, amphiphilic motifs do not rely on structural rigidity to support long-range order. Instead, the flexibility of amphiphilic DNA building-blocks is a crucial feature for successful crystallisation
Carbonic anhydrase inhibition for the management of cerebral ischemia: in vivo evaluation of sulfonamide and coumarin inhibitors.
Ischemia of brain areas is a global health problem, causing death or long-term disability. Current pharmacological options have limited impact on ischemic damages. Recently, a relationship between hypoxia and carbonic anhydrase (CA) over-expression has been highlighted suggesting CA inhibition as a possible target. This study aimed to evaluate the pharmacological profile of sulfonamide and coumarin CA inhibitors in rats underwent permanent middle cerebral artery occlusion (pMCAO). The neurological score of pMCAO rats was dramatically reduced 24 h after occlusion. Repeated subcutaneous injections of the CA inhibitors 4 and 7 (1 mg kg(-1)) were able to increase the neurological score by 40%. Compound 7 showed the tendency to reduce the volume of hemisphere infarction. The standard CA inhibitor acetazolamide was ineffective. The properties of novel CA inhibitors to improve neurological functionalities after cerebral ischemic insult are shown. The CA involvement in cerebral hypoxic phenomena deserves deeper investigations
Heterocoumarins Are Selective Carbonic Anhydrase IX and XII Inhibitors with Cytotoxic Effects against Cancer Cells Lines
We have synthesized
a new series of coumarin-based compounds demonstrating
high selectivity and potent effects with low nanomolar affinity against
the tumor associated carbonic anhydrase (CA, EC 4.2.1.1) isoforms
hCA IX and XII. A number of these compounds were evaluated ex vivo against human prostate (PC3) and breast (MDA-MB-231)
cancer cell lines. Compounds 4b and 15 revealed
effective cytotoxic effects after 48 h of incubation in both normoxic
and hypoxic conditions with PC3 cancer cell line. However, compound 3 showed selective cytotoxic effects against MDA-MB-231 in
hypoxic condition. These results may be of particular importance for
the choice of future drug candidates targeting hypoxic tumors and
metastases, considering the fact that a selective carbonic anhydrase
CA IX inhibitor (SLC-0111) is presently in phase II clinical trials
Predictors of unemployment status in people with relapsing multiple sclerosis: a single center experience
Background: Multiple sclerosis (MS) is the most common cause of nontraumatic chronic neurological disability affecting young adults during their crucial employment years. Objectives: To evaluate patients and disease related factors associated to unemployment in a cohort of relapsing–remitting (RR) MS patients. Methods: We included RRMS patients with a follow-up of at least 1 year. We collected data about years of school education and employment status. Patients underwent a neuropsychological evaluation using the Brief International Cognitive Assessment for Multiple Sclerosis (BICAMS). Demographic and clinical predictors of unemployment were assessed through a multivariable stepwise logistic regression model. Results: We evaluated 260 consecutive RRMS patients. Employed patients were less frequently female (68.4% vs 83.3%, p = 0.006), less disabled (median Expanded Disability Status Scale (EDSS) score: 2.0 (0–7.0) vs 2.5 (0–7.5), p < 0.001), with more years of school education (mean ± standard deviation (SD), years: 13.74 ± 0.30 vs 10.86 ± 3.47, p < 0.001). Female sex and a higher EDSS score resulted associated with a greater risk of unemployment (OR 3.510, 95% CI 1.654–7.448, p = 0.001; OR 1.366, 95% CI 1.074–1.737, p = 0.011, respectively), whereas a greater number of years of schooling and current disease-modifying therapy exposure resulted protective factors (OR 0.788, 95% CI 0.723–0.858, p < 0,001; OR 0.414, 95% CI 0.217–0.790, p = 0.008, respectively). Conclusions: Understanding work is pervasively influenced by consequences of MS, we confirmed the impact of demographic, physical, and cognitive factors on employment status in RRMS patients
Integrable model for interacting electrons in metallic grains
We find an integrable generalization of the BCS model with non-uniform
Coulomb and pairing interaction. The Hamiltonian is integrable by construction
since it is a functional of commuting operators; these operators, which
therefore are constants of motion of the model, contain the anisotropic Gaudin
Hamiltonians. The exact solution is obtained diagonalizing them by means of
Bethe Ansatz. Uniform pairing and Coulomb interaction are obtained as the
``isotropic limit'' of the Gaudin Hamiltonians. We discuss possible
applications of this model to a single grain and to a system of few interacting
grains.Comment: 4 pages, revtex. Revised version to be published in Phys. Rev. Let
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