1,723,509 research outputs found
Large-scale albuminuria screen for nephropathy models in chemically induced mouse mutants
Full text linkBackground/Aim: Phenotype-driven screening of a great pool of randomly mutant mice and subsequent selection of animals showing symptoms equivalent to human kidney diseases may result in the generation of novel suitable models for the study of the pathomechanisms and the identification of genes involved in kidney dysfunction. Methods: We carried out a large-scale analysis of ethylnitrosourea (ENU)-induced mouse mutants for albuminuria by using qualitative SDS-polyacrylamide gel electrophoresis. Results: The primary albuminuria screen preceded the comprehensive phenotypic mutation analysis in a part of the mice of the Munich ENU project to avoid loss of mutant animals as a consequence of prolonged suffering from severe nephropathy. The primary screen detected six confirmed phenotypic variants in 2,011 G1 animals screened for dominant mutations and no variant in 48 G3 pedigrees screened for recessive mutations. Further breeding experiments resulted in two lines showing a low phenotypic penetrance of albuminuria. The secondary albuminuria screen was carried out in mutant lines which were established in the Munich ENU project without preceding primary albuminuria analysis. Two lines showing increased plasma urea levels were chosen to clarify if severe kidney lesions are involved in the abnormal phenotype. This analysis revealed severe albuminuria in mice which are affected by a recessive mutation leading to increased plasma urea and cholesterol levels. Conclusion: Thus, the phenotypic selection of ENU-induced mutants according to the parameter proteinuria in principle demonstrates the feasibility to identify nephropathy phenotypes in ENU-mutagenized mice. Copyright (C) 2005 S. Karger AG, Basel
Enu mouse mutagenesis: generation of mouse mutants with aberrant plasma IgE levels.
Full text linkpeer reviewedBACKGROUND: The ENU Mouse Mutagenesis Project aims at a large-scale, systematic production of mouse mutants using the alkylating agent ethyl-nitrosourea (ENU). Offspring of mutagenized mice are subjected to a multiparameter screen to detect alterations in various phenotypes with the ultimate goal of identifying novel genes relevant for the expression of the phenotype. Using this approach, we have analyzed plasma IgE concentrations to identify mouse mutants with aberrant plasma IgE levels. METHODS AND RESULTS: ENU-mutagenized male C3HeB/FeJ were mated to wild-type females to produce F1 offspring. F1 animals were analyzed for alterations in their plasma IgE concentrations that showed a dominant mode of inheritance, or bred further to screen for recessive phenotypes. Plasma IgE concentrations were determined by ELISA and a normal range for plasma IgE was established using C3HeB/FeJ wild-type animals. So far we have tested 6568 F1 animals. Repeated testing confirmed a stable aberrant IgE phenotype in 124 animals. To confirm the genetic basis of the observed phenotype, these mice were subjected to confirmation crossing. Currently we have established 9 independent mutant mouse lines (3 with high plasma IgE and 6 with plasma IgE below detection limit) that have been genetically confirmed and additional 24 variant mouse lines are currently undergoing confirmation testing. CONCLUSION: ENU mouse mutagenesis allowed us to generate and identify mouse mutants with aberrant plasma IgE levels, which may be used to characterize novel genes involved in IgE regulation and may serve as animal models for IgE-mediated diseases
Valutare le competenze del docente inclusivo: revisione sistematica nei corsi di specializzazione sul sostegno in Italia
No full textLa formazione degli insegnanti assume oggi una primaria importanza nella realizzazione di un sistema scolastico equo e inclusivo, consentendo ai docenti la possibilità di acquisire le necessarie competenze per rispondere in maniera congrua alle diverse esigenze di tutti gli alunni. In Italia, nell’ambito dei percorsi di formazione per il conseguimento della specializzazione per l’attività di sostegno didattico agli alunni con disabilità, differenti sono le modalità impiegate per valutare l’efficacia dei suddetti corsi e, in particolare, le competenze acquisite alla fine del percorso formativo. L’obiettivo del lavoro è dunque quello di delineare, mediante una revisione sistematica, un quadro comparativo degli strumenti utilizzati per valutare le competenze dei corsisti alla fine del percorso formativo, nonché i profili di competenza cui si riferiscono. A tal fine, sono stati presi in considerazione N=12 studi primari pubblicati in open access dal 2011 al 2020. La sintesi descrittiva ricavata dall’indagine può essere utile per realizzare modelli di valutazione e learning outcomes condivisi per i docenti che si specializzano nelle attività di sostegno didattico
Dynamics of neural system under the influence of a magnetic flux
No full textAn autonomous model describing biological aspects of synapses affected by electromagnetic fields, is considered. A quaternary system comparable to the third-order FitzHuh–Rinzel (FHR) model is obtained. Linear stability criteria and conditions for Hopf bifurcations are achieved also by means of a ternary auxiliary spectrum showing that some of the resulting conditions recall those related to critical solutions of the FHR system
Experimental Dynamic Response of a Multi-Story Frame Structure Equipped with Non-Conventional TMD Implemented via Inter-Story Isolation
Full text linkA shaking table experiment conducted on a multi-degrees-of-freedom frame structure equipped with a non-conventional tuned mass damper (TMD) is presented. The non-conventional TMD is characterized by a high mass ratio, without adding further structural masses, and is realized via inter-story isolation. The structure top story mass of a four-story steel frame structure is isolated and converted into tuned mass, connecting to the substructure with two high damping rubber bearings placed in series. Aspects related to the dynamic structural response as well as the seismic effectiveness assessment of a non-conventional TMD are addressed. Three structural configurations are tested: the reference four-story structure, the three-story intermediate structure, and the three-story structure equipped with a non-conventional TMD. The input motion conditions considered are: white noise, sine sweep, and natural earthquakes. Through experiments, structural identification is carried out and different dynamic behaviors emerge for the configurations tested. The nonlinear effects provoked on the structure by the adopted isolators are investigated, showing high dissipative capabilities in a wide range of amplitudes of the excitation. It is demonstrated that a non-conventional TMD is a smart control strategy useful for enhancing structural vibration mitigation
Influence of the characteristics of isolation and mitigation devices on the response of single-degree-of-freedom vibro-impact systems with two-sided bumpers and gaps via shaking table tests
Full text linkDuring strong earthquakes, structural pounding may occur between structures (buildings, bridges, strategic facilities, critical equipment, etc.) and the surrounding moat wall because of the limited separation distance and the deformations of the isolator. An arrangement that favors the solution of this problem is the interposition of shock absorbers. Thus, the influence of geometrical and mechanical characteristics of isolation and mitigation devices on nonlinear, nonsmooth response of vibro-impact systems is experimentally investigated in this paper on the basis of a laboratory campaign of experimental tests. Shaking table tests were carried out under a harmonic excitation in order to investigate two different configurations: the absence and the presence of bumpers. Three different values of the table acceleration peak were applied, four different amplitude values of the total gap between mass and bumpers were considered, and also four different types of bumpers were employed; moreover, two problems were addressed, namely, control of excessive displacements and control of excessive accelerations, and hence, two types of normalization were adopted in order to better interpret experimental results. Suitable choices of pairs of bumpers and gaps were suggested as a trade-off between conflicting objectives. Furthermore, a numerical model was proposed, and its governing parameters identified in order to simulate the experimental results
Lactobacillus sanfranciscensis CB1: manganese, oxygen, superoxide dismutase and metabolism.
No full textOn the thermodynamics of Barium Oxyfluoride precursor in YBCO growth via the MOD process
Full text linkBarium Oxyfluoride plays an important role, as a precursor species, in the nucleation and growth of YBa2Cu3O7-delta (YBCO) via the low fluorine metal organic decomposition (MOD low-fluorine) route. In this contribution, we present a study on the thermodynamics of oxyfluoride by processing experimental data on YBCO growth on LaAlO3 (LAO) substrates. The analysis allows one to determine the standard enthalpy and the standard entropy changes for oxyfluoride formation from barium oxide and barium fluoride. To identify the thermodynamically more favorable route to oxyfluoride formation in the MOD low-fluorine process, the free energy change for the formation of the precursor, through reactions involving gas water, has been determined. The free energy of formation via fluoride and water indicates higher stability of oxygen rich oxyfluoride for P-HF(2)/PH2O < 10(-6). In the framework of nucleation theory, the present results are needed to study the effect of precursor composition on film orientation
Fokker-Planck equation for the crystal-size probability density in progressive nucleation and growth with application to lognormal, Gaussian and gamma distributions
Full text linkThe Fokker Planck (FP) equation for the probability density function (PDF) of crystal size in phase transformations ruled by progressive nucleation and growth, has been derived. Crystals are grouped in sub-sets, we
refer to as τ-crystals, where τ is the birth time of the set. It is shown that the size PDF is the superposition of the
PDF of the crystal sub-sets (τ-PDFs), with weight given by the nucleation rate. The growth and diffusion coefficients entering the FP equations are estimated as a function of both τ-PDFs and nucleation rate. The functional
form of these coefficients is studied for solutions of the FP equation for τ-crystals given by the lognormal,
Gaussian and gamma distributions. For the first two distributions, the effect of fluctuations, nucleation rate and
growth rate, on the shape of the distribution has been investigated. It is shown that for an exponential decay of
the fluctuation term, the shape of the PDF is mainly governed by both the time constant for nucleation and the
strength of the fluctuation. It is found that τ-PDFs given by the one-parameter gamma distributions are suitable to
deal with KJMA (Kolmogorov Johnson Mehl Avrami) compliant phase transformations, where the fluctuation
term is proportional to crystal size. The connection between the FP equation for the size PDF and the evolution
equation for the density of crystal populations is also discussed
Investigation on the optimal properties of semi active control devices with continuous control for equipment isolation
No full textThe paper treats the semi active isolation of a single equipment, acceleration sensitive, by means of a variable elastic control device. A numerical study on a single degree of freedom (SDOF) structural model equipped with a continuously variable elastic device subjected to harmonic input is presented. The utilized control algorithm is derived by the Lyapunov method and specialized in order to obtain instantaneous optimality. In order to minimize the dynamic response of interest, i.e. the equipment absolute acceleration, some parameters that define the algorithm and the device are conveniently selected. The purpose of the paper is to investigate the optimal isolation properties of semi active variable stiffness devices with continuous control across the whole frequency spectrum. The performances of the isolated equipment are evaluated in terms of absolute acceleration transmissibility. Semi active continuous control is compared with semi active ON-OFF mode and conventional linear passive control. Results show that it is possible to choose conveniently the parameters regulating semi active continuous control in order to limit the absolute acceleration transmissibility at all the frequencies. In literature from problems concerning vibration isolation, transmissibility is alternatively defined in terms of absolute acceleration or displacement. Here, absolute displacement transmissibility is also estimated. It is observed that in case of semi active control, there are differences between the two transmissibility representations, and they do not lead to analogous results for evaluating the performance of the control system
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