560 research outputs found
Numerical Simulation of the Performance of a Twin Scroll Radial Turbine at Different Operating Conditions
Twin scroll radial turbines are increasingly used for turbocharging applications, to take advantage of the pulsating exhaust gases. In spite of its relevance in turbocharging techniques, scientific literature about CFD applied to twin scroll turbines is limited, especially in case of partial admission. In the present paper a CFD complete model of a twin scroll radial turbine is developed in order to give a contribution to literature in understanding the capabilities of current industrial CFD approaches applied to these difficult cases and to develop performance index that can be used for turbine design optimization purposes. The flow solution is obtained by means of ANSYS CFX \uae in a wide range of operating conditions in full and partial admission cases. The total-to-static efficiency and the mass flow parameter (MFP) have been calculated and compared with the experimental database in order to validate the numerical model. The purpose of the developed procedure is also to generate a database for twin scroll turbines useful for future applications. A comparison between performances obtained in different admission conditions was performed. In particular the analysis focused on the characterization of the flow at volute outlet/rotor inlet section. A flow distortion index at rotor inlet was introduced to correlate the turbine performance and the flow nonuniformities generated by the volute. Finally the influence of the backside cavity on the performance parameters is also discussed. The introduction of these new nonuniformity indices is proposed for volute design and optimization procedures
Rasch analysis of the Fatigue Severity Scale in Italian subjects with multiple sclerosis.
To perform a psychometric analysis of the Fatigue Severity Scale (FSS) using Rasch analysis in a sample of Italian subjects with multiple sclerosis
TDEM for Martian in situ resource prospecting missions
This paper presents a TDEM (Time Domain Electromagnetic Methods) application, addressed to the search
for water on Mars. In this context, the opportunities for a TDEM system as payload in a future mission are
investigated for different in situ exploration scenarios. The TDEM sounding capability is evaluated with respect
to the expected Martian environment, and some considerations are made about the many unknown variables
(above all the background EM noise and the subsoil composition) altogether with the limited resources availability
(mission constraints in mass, time and power) and the way they could represent an obstacle for operations and
measurements
Survival of patients with spinal muscular atrophy type 1
BACKGROUND: Spinal muscular atrophy type 1 (SMA1) is a progressive disease and is usually fatal in the first year of life. METHODS: A retrospective chart review was performed of SMA1 patients and their outcomes according to the following choices: letting nature take its course (NT); tracheostomy and invasive mechanical ventilation (TV); continuous noninvasive respiratory muscle aid (NRA), including noninvasive ventilation; and mechanically assisted cough. RESULTS: Of 194 consecutively referred patients enrolled in this study (103 males, 91 females), NT, TV, and NRA were chosen for 121 (62.3%), 42 (21.7%), and 31 (16%) patients, respectively. Survival at ages 24 and 48 months was higher in TV than NRA users: 95% (95% confidence interval: 81.8%-98.8%) and 67.7% (95% confidence interval: 46.7%-82%) at age 24 months (P < .001) and 89.43% and 45% at age 48 months in the TV and NRA groups, respectively (P < .001). The choice of TV decreased from 50% (1992-1998) to 12.7% (2005-2010) (P < .005) with a nonstatistically significant increase for NT from 50% to 65%. The choice of NRA increased from 8.1% (1999-2004) to 22.7% (2005-2010) (P < .001). CONCLUSIONS: Long-term survival outcome is determined by the choice of the treatment. NRA and TV can prolong survival, with NRA showing a lower survival probability at ages 24 and 48 months. Copyright © 2013 by the American Academy of Pediatrics
Urinary metabolomics (GC-MS) reveals that low and high birth weight infants share elevated inositol concentrations at birth
Objective: Metabolomics is a new ‘‘omics’’ platform aimed at high-throughput identification, quantification and characterization of small molecule metabolites. The metabolomics approach has been successfully applied to the classification different physiological states and identification of perturbed biochemical pathways. The purpose of the current investigation is the application of metabolomics to explore biological mechanisms which may lead to the onset
of metabolic syndrome in adulthood.
Methods: We evaluated differences in metabolites in the urine collected within 12 hours from 23 infants with IUGR (IntraUterine Growth Restriction), or LGA (Large for Gestational Age), compared to control infants (10 patients defined AGA: Appropriate for Gestational Age). Urinary metabolites were quantified by GC-MS and used to highlight similarities between the two metabolic diseases and identify metabolic markers for their predisposition. Quantified metabolites were analyzed using a multivariate statistics coupled with receiver operator characteristic curve (ROC) analysis of identified biomarkers.
Results: Urinary myo-inositol was the most important discriminant between LGA + IUGR and control infants, and displayed an area under the ROC curve¼1.
Conclusion: We postulate that the increase in plasma and consequently urinary inositol may constitute a marker of altered glucose metabolism during fetal development in both IUGR and LGA newborns
Compton Scattering by the Proton using a Large-Acceptance Arrangement
Compton scattering by the proton has been measured using the tagged-photon
facility at MAMI (Mainz) and the large-acceptance arrangement LARA. The new
data are interpreted in terms of dispersion theory based on the SAID-SM99K
parameterization of photo-meson amplitudes. It is found that two-pion exchange
in the t-channel is needed for a description of the data in the second
resonance region. The data are well represented if this channel is modeled by a
single pole with mass parameter m(sigma)=600 MeV. The asymptotic part of the
spin dependent amplitude is found to be well represented by pi-0-exchange in
the t-channel. A backward spin-polarizability of
gamma(pi)=(-37.1+-0.6(stat+syst)+-3.0(model))x10^{-4}fm^4 has been determined
from data of the first resonance region below 455 MeV. This value is in a good
agreement with predictions of dispersion relations and chiral pertubation
theory. From a subset of data between 280 and 360 MeV the resonance
pion-photoproduction amplitudes were evaluated leading to a E2/M1 multipole
ratio of the p-to-Delta radiative transition of EMR(340
MeV)=(-1.7+-0.4(stat+syst)+-0.2(model))%. It was found that this number is
dependent on the parameterization of photo-meson amplitudes. With the MAID2K
parameterization an E2/M1 multipole ratio of EMR(340
MeV)=(-2.0+-0.4(stat+syst)+-0.2(model))% is obtained
Notulae to the Italian flora of algae, bryophytes, fungi and lichens: 2
In this contribution, new data concerning red algae, lichens and bryophytes of the Italian flora are presented. It includes new records and confirmations for the algal genus Grateloupia, the bryophyte genus Didymodon, and the lichen genera Buellia, Cladonia, Letharia, Pertusaria, and Pyrenula
Targeting p53 and histone methyltransferases restores exhausted CD8+ T cells in HCV infection
Hepatitis C virus infection (HCV) represents a unique model to characterize, from early to late stages of infection, the T cell differentiation process leading to exhaustion of human CD8+ T cells. Here we show that in early HCV infection, exhaustion-committed virus-specific CD8+ T cells display a marked upregulation of transcription associated with impaired glycolytic and mitochondrial functions, that are linked to enhanced ataxia-telangiectasia mutated (ATM) and p53 signaling. After evolution to chronic infection, exhaustion of HCV-specific T cell responses is instead characterized by a broad gene downregulation associated with a wide metabolic and anti-viral function impairment, which can be rescued by histone methyltransferase inhibitors. These results have implications not only for treatment of HCV-positive patients not responding to last-generation antivirals, but also for other chronic pathologies associated with T cell dysfunction, including cancer
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