5,619 research outputs found
The incidence of regional factors on "competitive performanceâ of universities
The performance of single universities, beyond internal determinants, is influenced by the conditions of their own territorial context, that is by a number of factors related to their local geographical area, meant as a space of territorial interactions, measurable by its previous relational dynamics. This set of factors can, directly or indirectly, affect both the organizational structure and strategic orientations of the single university, as well as the results achieved by it in the field of education and research.Through a multi-dimensional statistical model, the evaluation criteria for university performance will be compared to some territorial variables which, in scientific literature, are considered to be indexes of territorial competitiveness. The statistical model aims at measuring the impact local context has on the competitive performance of universities, explaining the nature and intensity of this relationship. With reference to the objectives of the research, data we will use refer to two different sets of indicators: on the one hand, data used to evaluate university performance, on the other hand, the ones used to measure territorial competitiveness. In more detail, university performance is based on some of the indicators used by the CENSIS in the "University Ranking 2010" referring to the following databases: MIUR-Statistical Office; CINECA; CNVSU; National LLP Agency Italy; CRUI; CORDIS. Territorial data, instead, are extracted from the "Atlas of the Provinces and Regions competitivenessâ elaborated by UNIONCAMERE. For both sets of indicators, the analysis will refer to the year 2008.If the indicators of university performance are correlated to territorial conditions, they donât really measure university productivity/competitiveness, but rather the competitiveness of its territorial context. This can lead to some distortions in the financial resources allocation and, more generally, in national supporting policies to public universities.In their conclusions, authors also tend to reverse the perspective through which the role of government intervention has been traditionally interpreted. If universities are qualifying elements of territorial competitiveness â as it is shown by the fact that they are frequently used within the set of indicators to measure it â the strengthening of university system should be one of the priority objectives of regional development policies. Consequently, national government should invest in university education and research, even where university performance, due to some specific local conditions, is not satisfactory or even below fixed national or international standards.
Variations of the initial mass function in semi-analytical models: implications for the mass assembly and the chemical enrichment of galaxies in the GAEA model
In this work, we investigate the implications of the Integrated Galaxy-wide
stellar Initial Mass Function (IGIMF) approach in the framework of the
semi-analytic model GAEA (GAlaxy Evolution and Assembly), which features a
detailed treatment of chemical enrichment and stellar feedback. The IGIMF
provides an analytic description of the dependence of the stellar IMF shape on
the rate of star formation in galaxies. We find that our model with a universal
IMF predicts a rather flat [/Fe]-stellar mass relation. The model
assuming the IGIMF, instead, is able to reproduce the observed increase of
-enhancement with stellar mass, in agreement with previous studies.
This is mainly due to the fact that massive galaxies are characterized by
larger star formation rates at high-redshift, leading to stronger
-enhancement with respect to low-mass galaxies. At the same time, the
IGIMF hypothesis does not affect significantly the trend for shorter star
formation timescales for more massive galaxies. We argue that in the IGIMF
scenario the [/Fe] ratios are good tracers of the highest star
formation events. The final stellar masses and mass-to-light-ratio of our model
massive galaxies are larger than those estimated from the synthetic photometry
assuming a universal IMF, providing a self-consistent interpretation of similar
recent results, based on dynamical analysis of local early type galaxies.Comment: 14 pages, 8 figures, 2 tables, submitted to MNRA
A semi-analytic model comparison: testing cooling models against hydrodynamical simulations
We compare predictions of cooled masses and cooling rates from three
stripped-down Semi-Analytic Models (SAMs) of galaxy formation with the results
of N-body+SPH simulations with gas particle mass of 3.9x10^6 Msun, where
radiative cooling of a gas of primordial composition is implemented. We also
run a simulation where cooling is switched on at redshift ~2, in order to test
cooling models in a regime in which their approximations are expected to be
valid. We confirm that cooling models implemented in SAMs are able to predict
the amount of cooled mass at z=0 to within ~20 per cent. However, some relevant
discrepancies are found. (i) When the contribution from poorly resolved halos
is subtracted out, SAMs tend to under-predict by ~30 per cent the mass that
cools in the infall-dominated regime. (ii) At large halo masses SAMs tend to
over-predict cooling rates, though the numerical result may be affected by the
use of SPH. (iii) As found in our previous work, cooling rates are found to be
significantly affected by model details: simulations disfavour models with
large cores and with quenching of cooling at major mergers. (iv) When cooling
is switched on at z~2, cold gas accumulates very quickly in the simulated
halos. This accumulation is reproduced by SAMs with varying degrees of
accuracy.Comment: 20 pages, 12 figures, accepted by MNRA
TG, FT-IR and NMR characterization of n-C16H34 contaminated alumina and silica after mechanochemical treatment
This paper deals with the application of mechanochemistry to model systems composed of alumina or silica artificially contaminated with n-C16H34. The mechanochemical treatment was carried out by means of a ring mill for times ranging from 10 to 40 h. Thermogravimetry and infrared and nuclear magnetic resonance spectroscopies were used for the characterization of the mechanochemical products. The results have indicated that, in the case of alumina, almost all the contaminant n-C16H34 undergoes a complex oxidative reaction path whose end products are strongly held on the surface. These end products are most likely made of crosslinked, partially oxidized hydrocarbon chains bond to the solid surface via COOâ groups. In the case of silica, the hydrocarbon undergoes a different, equally complex reaction path, but to a lower extent. In this case the end products are most probably carbonylic compounds and graphitic carbon. Then, for both solid matrices, the mechanochemical treatment promotes significant modification of the chemical nature of the polluting hydrocarbon with end products much more difficult to remove from the surface. As the systems studied are models of sites contaminated by aliphatic hydrocarbon, the results are worthy of consideration in relation to the mobility of the contaminants in the environment
L'obesitĂ , la forza muscolare, la composizione muscolare e la performance fisica in una popolazione anziana
Objective: To evaluate the association between BMI levels, muscular strength, muscle composition and physical performance, in a follow-up of 6 years, in an elderly population.
Materials and Methods: 2911 Italians subjects aged > 65 years from the Progetto Veneto Anziani (ProVA) study were analyzed. ProVA was a population study focused on chronic diseases and functional limitations. Physical performance with the Short Physical Performance Battery (SPPB) and leg muscular strength with dynamometry were measured in all subjects both at baseline and at the end of follow-up.. Fat distribution and skeletal muscle composition were measured in an abdominal single-scan magnetic resonance (MRI) in a randomly selected sample of 348 subjects at baseline. Study population was stratified by six BMI classes: underweight (BMI<18.5 kg/m2), normal weight (BMI 18.5-24.9), overweight (BMI 25.0-29.9), obesity I level (30.0-34.9), obesity II level (35.0-39.9), and severe obesity (BMIâ„40.0). Associations between BMI levels, muscular strength, muscle compositions and physical performance were analyzed in multivariable adjusted models.
Results: In the ProVA population, an association between BMI levels and SPPB was observed. Normal weight subjects showed, in a sex and age-adjusted model, the best SPPB scores (8.29±0.03), with significant differences compared to underweight (7.50±0.15; p<0.001), overweight (8.12±0.02; p<0.001), class I (7.72±0.04; p<0.001), class II (6.67±0.09; p<0.001) and class III obesity (5.88±0.24; p<0.001). This pattern was not modified by further adjustment for socio-economic status, smoke, physical activity level and comorbidities. Compared to normal weight subjects (22.9±0.1 kg), leg muscular strength was higher in overweight (23.8±0.1; p<0.001) and in class I obesity (24.5±0.1; p<0.001), but it was reduced in class II (21.4±0.3; p<0.001) and class III obesity (19.8±0.9; p<0.001). The association between BMI and impaired physical performance was not significantly affected by adjustment for leg muscular strength. In a multiple logistic analysis, performed after the exclusion of subjects with at the baseline value <3 in the SPPB test, and adjusting for age, sex, smoking, income, education, physical activity and chronic disease, a significant increased risk of a statistically significant reduction in SPPB test was observed for overweight and obese subjects.
In the subgroup of patients with abdominal MRI, at the baseline, an inverse association between SPPB scores and the degree of fat infiltration of skeletal muscle was observed.
Conclusion: A poor physical performance was observed in overweight and obese elderly subjects, whereas leg muscular strength was reduced only in subjects with more severe obesity. The physical performance was negatively influenced by the degree of fat infiltration in skeletal muscle. Moreover, an increased risk of worsening in physical performance during the years was found in overweight and obese as compared to normal weight subjects. In conclusion high BMI values affect negatively physical performance and expose the elderly to a risk of a further decline in physical performance with consequent disabilit
Hierarchical 1D/3D Approach for the Development of a Turbulent Combustion Model Applied to a VVA Turbocharged Engine. Part II: Combustion Model
As discussed in the part I of this paper, 3D models represent a useful tool for a detailed description of the mean and turbulent flow fields inside the engine cylinder. 3D results are utilized to develop and validate a 0D phenomenological turbulence model, sensitive to the variation of operative parameters such as valve phasing, valve lift, engine speed, etc. In part II of this paper, a 0D phenomenological combustion model is presented, as well. It is based on a fractal description of the flame front and is able to sense each of the fuel properties, the operating conditions (air-to-fuel ratio, spark advance, boost level) and the combustion chamber geometry. In addition, it is capable to properly handle different turbulence levels predicted by means of the turbulence model presented in the part I. The turbulence and combustion models are included, through user routines, in the commercial software GT-Power". With reference to a small twin-cylinder VVA turbocharged engine, the turbulence/combustion model, once properly tuned, is finally used to calculate in-cylinder pressure traces, rate of heat release and overall engine performance at full load operations and brake specific fuel consumption at part load, as well. An excellent agreement between numerical forecasts and experimental evidence is obtained
Hierarchical 1D/3D Approach for the Development of a Turbulent Combustion Model Applied to a VVA Turbocharged Engine. Part I: Turbulence Modelâ
Abstract It is widely recognized that air-fuel mixing, combustion and pollutant formation inside internal combustion engines are strongly influenced by the spatial and temporal evolution of both marco- and micro- turbulent scales. Particularly, in spark ignited engines, the generation of a proper level of turbulence intensity for the correct development of the flame front is traditionally based on the onset, during the intake and compression strokes, of a tumbling macro-structure. Recently, in order to both reduce pumping losses due to throttling and develop advanced and flexible engine control strategies, fully variable valve actuation systems have been introduced, capable of simultaneously governing both valve phasing and lift. Despite the relevant advantages in terms of intake system efficiency, this technology introduces uncertainties on the capability of the intake port/valve assembly to generate, at low loads, sufficiently coherent and stable structures, able therefore to promote adequate turbulence levels towards the end of the compression, with relevant effects on the flame front development. It is a common knowledge that 3D-CFD codes are able to describe the evolution of the in-cylinder flow field and of the subsequent combustion process with good accuracy; however, they require too high computational time to analyze the engine performance for the whole operating domain. On the contrary, this task is easily accomplished by 1D codes, where, however, the combustion process is usually derived from experimental measurements of the in-cylinder pressure trace (Wiebe correlation). This approach is poorly predictive for the simulation of operating conditions relevantly different from the experimental ones. To overcome the above described issues, enhanced physical models for the description of in-cylinder turbulence evolution and combustion to be included in a 1D modeling environment are mandatory. In the present paper (part I), a 0D (i.e. homogeneous and isotropic) phenomenological (i.e. sensitive to the variation of operative parameters such as valve phasing, valve lift, intake and exhaust pressure levels, etc.) turbulence model belonging to the K-k model family is presented in detail. The model is validated against in-cylinder results provided by 3D-CFD analyses carried ou
A pH-sensitive stearoyl-PEG-poly(methacryloyl sulfadimethoxine)-decorated liposome system for protein delivery: an application for bladder cancer treatment
Stealth pH-responsive liposomes for the delivery of therapeutic proteins to the bladder epithelium were prepared using methoxy-poly(ethylene glycol)5kDa-1,2-distearoyl-sn-glycero-3-phosphoethanolamine (mPEG5kDa-DSPE) and stearoyl-poly(ethylene glycol)-poly(methacryloyl sulfadimethoxine) copolymer (stearoyl-PEG-polySDM), which possesses an apparent pKa of 7.2. Liposomes of 0.2:0.6:100, 0.5:1.5:100 and 1:3:100 mPEG5kDa-DSPE/stearoyl-PEG-polySDM/(soybean phosphatidylcholine + cholesterol) molar ratios were loaded with bovine serum albumin (BSA) as a protein model. The loading capacity was 1.3% w/w BSA/lipid. At pH 7.4, all liposome formulations displayed a negative zeta-potential and were stable for several days. By pH decrease or addition to mouse urine, the zeta potential strongly decreased, and the liposomes underwent a rapid size increase and aggregation. Photon correlation spectroscopy (PCS) and transmission electron microscopy (TEM) analyses showed that the extent of the aggregation depended on the stearoyl-PEG-polySDM/lipid molar ratio. Cytofluorimetric analysis and confocal microscopy showed that at pH 6.5, the incubation of MB49 mouse bladder cancer cells and macrophages with fluorescein isothiocyanate-labelled-BSA (FITC-BSA) loaded and N-(Lissamine Rhodamine B sulfonyl)-1, 2-dihexadecanoyl-sn-glycero-3-phosphoethanolamine triethylammonium salt (rhodamine-DHPE) labelled 1:3:100 mPEG5kDa-DSPE/stearoyl-PEG-polySDM/lipid molar ratio liposomes resulted in a time-dependent liposome association with the cells. At pH 7.4, the association of BSA-loaded liposomes with the MB49 cells and macrophages was remarkably lower than at pH 6.5. Confocal images of bladder sections revealed that 2 h after the instillation, liposomes at pH 7.4 and control non-responsive liposomes at pH 7.4 or 6.5 did not associate nor delivered FITC-BSA to the bladder epithelium. On the contrary, the pH-responsive liposome formulation set at pH 6.5 and soon administered to mice by bladder instillation showed that, 2 h after administration, the pH-responsive liposomes efficiently delivered the loaded FITC-BSA to the bladder epitheliu
The Quantum Frontier of Software Engineering: A Systematic Mapping Study
Context. Quantum computing is becoming a reality, and quantum software
engineering (QSE) is emerging as a new discipline to enable developers to
design and develop quantum programs.
Objective. This paper presents a systematic mapping study of the current
state of QSE research, aiming to identify the most investigated topics, the
types and number of studies, the main reported results, and the most studied
quantum computing tools/frameworks. Additionally, the study aims to explore the
research community's interest in QSE, how it has evolved, and any prior
contributions to the discipline before its formal introduction through the
Talavera Manifesto.
Method. We searched for relevant articles in several databases and applied
inclusion and exclusion criteria to select the most relevant studies. After
evaluating the quality of the selected resources, we extracted relevant data
from the primary studies and analyzed them.
Results. We found that QSE research has primarily focused on software
testing, with little attention given to other topics, such as software
engineering management. The most commonly studied technology for techniques and
tools is Qiskit, although, in most studies, either multiple or none specific
technologies were employed. The researchers most interested in QSE are
interconnected through direct collaborations, and several strong collaboration
clusters have been identified. Most articles in QSE have been published in
non-thematic venues, with a preference for conferences.
Conclusions. The study's implications are providing a centralized source of
information for researchers and practitioners in the field, facilitating
knowledge transfer, and contributing to the advancement and growth of QSE
Refinement of a 0D Turbulence Model to Predict Tumble and Turbulent Intensity in SI Engines. Part II: Model Concept, Validation and Discussion
As known, reliable information about underlying turbulence intensity is a mandatory pre-requisite to predict the burning rate in quasi-dimensional combustion models. Based on 3D results reported in the companion part I paper, a quasi-dimensional turbulence model, embedded under the form of "user routine" in the GT-Power\u2122 software, is here presented in detail. A deep discussion on the model concept is reported, compared to the alternative approaches available in the current literature. The model has the potential to estimate the impact of some geometrical parameters, such as the intake runner orientation, the compression ratio, or the bore-to-stroke ratio, thus opening the possibility to relate the burning rate to the engine architecture. Preliminarily, a well-assessed approach, embedded in GT-Power commercial software v.2016, is utilized to reproduce turbulence characteristics of a VVA engine. This test showed that the model fails to predict tumble intensity for particular valve strategies, such LIVC, thus justifying the need for additional refinements. The model proposed in this work is conceived to solve 3 balance equations, for mean flow kinetic energy, tumble vortex momentum, and turbulent kinetic energy (3-eq. concept). An extended formulation is also proposed, which includes a fourth equation for the dissipation rate, allowing to forecast the integral length scale (4-eq. concept). The impact of the model constants is parametrically analyzed in a first step, and a tuning procedure is advised. Then, a comparison between the 3- and the 4-eq. concepts is performed, highlighting the advantages of the 3-eq. version, in terms of prediction accuracy of turbulence speed-up at the end of the compression stroke. An extensive 3-eq. model validation is then realized according to different valve strategies and engine speeds. The user-model is then utilized to foresee the effects of main geometrical parameters analyzed in part I, namely the intake runner orientation, the compression ratio, and the bore-to-stroke ratio. A two-valve per cylinder engine is also considered. Temporal evolutions of 0D- and 3D-derived mean flow velocity, turbulent intensity, and tumble velocity present very good agreements for each investigated engine geometry and operating condition. The model, particularly, exhibits the capability to accurately predict the tumble trends by varying some geometrical parameter of the engine, which is helpful to estimate the related impact on the burning rate. Summarizing, the developed 0D model well estimates the in-cylinder turbulence characteristics, without requiring any tuning constants adjustment with engine speed and valve strategy. In addition, it demonstrates the capability to properly take into account the intake duct orientation and the compression ratio without tuning adjustments. Some minor tuning variation allows predicting the effects of bore-to-stroke ratio, as well. Finally, the model is verified to furnish good agreements also for a two-valve per cylinder engine, and with reference to two different high-performance engines
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