311 research outputs found
Financial Fragility in the Current European crisis
The paper argues that the European financial system in the years following the great financial crisis started in 2007 has become increasingly fragile. Minsky’s notion of fragility, on which it is based, is related to history, policy and institutions. In the current European environment, fragility depends on the rise of shadow banks’ assets, the expansion of derivatives and the changes in financial regulation. All these elements have jointly triggered several feedback loops. In Minsky’s opinion, policies should have the scope of thwarting self-enforcing feedback loops. Yet the policies that have been implemented so far seem to have produced the opposite effects. They have created new feedback loops that nurture fragility again. This outcome, however, is not surprising for policies may change initial conditions and have unintended consequences, as Minsky has taught us since a long time
Parametri di intensitĂ sismica per la stima degli spostamenti permanenti di pendii omogenei
Gli attuali criteri di progettazione in condizioni sismiche si avvalgono di procedure legate alla valutazione della prestazione del sistema espressa in termini di perdite quantificabili (costi di riparazione), di funzionalità o di beni inestimabili (vite umane, beni storico-culturali). In tale ottica il parametro rappresentativo della risposta è correlato attraverso procedure più o meno sofisticate a uno o più parametri che descrivano le caratteristiche del moto sismico. La scelta di tali parametri deve essere effettuata attraverso criteri di efficienza e sufficienza (cfr. p.es. Tothong & Luco, 2007; Luco & Cornell, 2007) inoltre devono poter essere prevedibili attraverso opportune leggi di ricorrenza.
In tale ambito, la presente nota propone una applicazione dei criteri citati per la stima della curva di pericolosità degli spostamenti cosismici dei pendii e per la valutazione critica dell’efficienza dei parametri di intensità del moto considerati significativi. In particolare vengono confrontate alcune relazioni indicate nella letteratura nazionale ed internazionale, e viene presentata una relazione che tiene conto dell’intensità di Housner, IH, quale parametro efficace per la stima degli spostamenti. Per la previsione del parametro IH viene proposta, inoltre, una legge di attenuazione in funzione di magnitudo e distanza
Tc=21K in epitaxial FeSe0.5Te0.5 thin films with biaxial compressive strain
High purity epitaxial FeSe0.5Te0.5 thin films with different thickness were
grown by Pulsed Laser Ablation on different substrates. By varying the film
thickness, Tc up to 21K were observed, significantly larger than the bulk
value. Structural analyses indicated that the a axis changes significantly with
the film thickness and is linearly related to the Tc. The latter result
indicates the important role of the compressive strain in enhancing Tc. Tc is
also related to both the Fe-(Se,Te) bond length and angle, suggesting the
possibility of further enhancement
Effect of grain refinement on enhancing critical current density and upper critical field in undoped MgB2 ex-situ tapes
Ex-situ Powder-In-Tube MgB2 tapes prepared with ball-milled, undoped powders
showed a strong enhancement of the irreversibility field H*, the upper critical
field Hc2 and the critical current density Jc(H) together with the suppression
of the anisotropy of all of these quantities. Jc reached 104 A/cm2 at 4.2 K and
10 T, with an irreversibility field of about 14 T at 4.2 K, and Hc2 of 9 T at
25 K, high values for not-doped MgB2. The enhanced Jc and H* values are
associated with significant grain refinement produced by milling of the MgB2
powder, which enhances grain boundary pinning, although at the same time also
reducing the connectivity from about 12% to 8%. Although enhanced pinning and
diminished connectivity are in opposition, the overall influence of ball
milling on Jc is positive because the increased density of grains with a size
comparable with the mean free path produces strong electron scattering that
substantially increases Hc2, especially Hc2 perpendicular to the Mg and B
planes.Comment: 26 pages, 9 figures, submitted to J. Appl. Phy
Prevalence of heavy smokers in the year 2000 in the province of Varese, Italy.
ABSTRACT: Prevalence of heavy smokers in the year
2000 in the Province of Varese, Italy. A. Imperatori, N.
Rotolo, V. Conti, D. Di Natale, V. Tropeano, W. Mantovani.
Background. Knowing the prevalence of heavy smokers
(HS) by gender and age is a pre-requisite for bringing
into effect public health measures against smoking-related
diseases. Smoking prevalence data is available for the Italian
Regions, however it is generally unknown for the Italian
Provinces.
Methods. In the year 2000 a survey of smoking prevalence
was conducted by 47 general practitioners (GPs), by
personal interview, in a large sample of the Varese
Province population 45-74 years of age (28,034 subjects;
13,528 men, 14,506 women). Each surveyed subject was
categorised either as ever HS (current/former smoker of
at least 10 pack-years) or as non HS. The information on
smoking habit collected by the GPs was anonymously
pooled for analysis. Prevalence figures of smoking were
tabulated by gender and by 5-year age-strata.
Results. In the population 45-74 years of age the percentage
of ever HS overall was 22.3% (34.4% of men;
11.0% of women). The prevalence of ever HS in both sexes
combined progressively decreased with advancing age,
from 23.6% (45-49 year stratum) to 19.5% (70-74 year stratum).
Current HS were 24.5% of men and 9.5% of women.
Conclusions. The year 2000 survey on smoking habit,
showing 22.3% prevalence of ever HS in age range 45-74
years, is the first conducted in the Varese Province using a
large population sample. The data on heavy cigarette
smoking presented in this paper, stratified by gender and
age, may be used to monitor changes in the smoking habit
and in the incidence of smoking-related illnesses at the
provincial level
From antiferromagnetism to superconductivity in Fe 1+y(Te1-x,Sex) (0 < x < 0.20): a neutron powder diffraction analysis
The nuclear and magnetic structure of Fe1+y(Te1-x,Sex) (0 < x < 0.20)
compounds was analyzed between 2 K and 300 K by means of Rietveld refinement of
neutron powder diffraction data. Samples with x < 0.075 undergo a tetragonal to
monoclinic phase transition at low temperature, whose critical temperature
decreases with increasing Se content; this structural transition is strictly
coupled to a long range antiferromagnetic ordering at the Fe site. Both the
transition to a monoclinic phase and the long range antiferromagnetism are
suppressed for 0.10 < x < 0.20. The onset of the structural and of the magnetic
transition remains coincident with the increase of Se substitution. The low
temperature monoclinic crystal structure has been revised. Superconductivity
arises for x > 0.05, therefore a significant region where superconductivity and
long range antiferromagnetism coexist is present in the pseudo-binary FeTe -
FeSe phase diagram.Comment: 33 pages, 4 tables, 13 figure
Generation of non-synchronous accelerograms for evaluate the seismic bridge response, including local site amplification.
Non-synchronous seismic actions particularly affect the behaviour of infrastructures with significant longitudinal extension, as bridges, interacting with the soil at surface or below ground level. Some authors state that non synchronism may increase by a large amount the structural response. Several acceleration records relative to different points of the ground with different soil profiles at distances meaningful for bridge analyses, are not available in data banks. The objective of this work is the generation of arrays of asynchronous signals at different points in space, starting from natural accelerograms related to a given seismic event, to increase the number of the available data. The computer code GAS has been modified to use natural accelerograms. The procedure has been applied to a real case, L’Aquila main-shock, for which records in different points of the free field are known
Salud Dental y Periodontal en Adultos de 60 Años y más
En una muestra de 108 adultos mayores de 60 años que recibieron asistencia en la Facultad de OdontologĂa de la Universidad Nacional del Nordeste, se determinĂł el estado de salud dental y periodontal y la asociaciĂłn de la cobertura de seguridad social en atenciĂłn de salud con la necesidad de prĂłtesis.El 56% eran mujeres; 65% tenĂa entre 60 - 69 años. 76% poseĂa obra social. ĂŤndice CPO-D promedio 25.31 - componente perdido promedio 22.13 (69.13%). Se hallĂł ausencia de enfermedad periodontal en 93.26% y 40% presentĂł O' Leary no compatible con salud. Pacientes sin prĂłtesis superiores 64% y 83% inferiores. Necesidad de prĂłtesis parcial inferior 43% y 25% superior, completa en el arco superior 34% y en el inferior 33%.De los sujetos con cobertura en salud 62% necesitaban prĂłtesis inferior y un 41% superior. En quienes no poseĂan cobertura en salud los porcentajes fueron menores, 20% y 18% respectivamente
Evidence for electromagnetic granularity in polycrystalline Sm1111 iron-pnictides with enhanced phase purity
We prepared polycrystalline SmFeAsO1-xFx (Sm1111) bulk samples by sintering
and hot isostatic pressing (HIP) in order to study the effects of phase purity
and relative density on the intergranular current density. Sintered and HIPped
Sm1111 samples are denser with fewer impurity phases, such as SmOF and the
grain boundary wetting phase, FeAs. We found quite complex magnetization
behavior due to variations of both the inter and intragranular current
densities. Removing porosity and reducing second phase content enhanced the
intergranular current density, but HIPping reduced Tc and the intragranular
current density, due to loss of fluorine and reduction of Tc. We believe that
the HIPped samples are amongst the purest polycrystalline 1111 samples yet
made. However, their intergranular current densities are still small, providing
further evidence that polycrystalline pnictides, like polycrystalline cuprates,
are intrinsically granular.Comment: 14 pages, 6 figure
Transport and superconducting properties of Fe-based superconductors: SmFeAs(O1-x Fx) versus Fe1+y (Te1-x, Sex)
We present transport and superconducting properties - namely resistivity,
magnetoresistivity, Hall effect, Seebeck effect, thermal conductivity, upper
critical field - of two different families of Fe-based superconductors, which
can be viewed in many respects as end members: SmFeAs(O1-xFx) with the largest
Tc and the largest anisotropy and Fe1+y(Te1-x,Sex), with the largest Hc2, the
lowest Tc and the lowest anisotropy. In the case of the SmFeAs(O1-xFx) series,
we find that a single band description allows to extract an approximated
estimation of band parameters such as carrier density and mobility from
experimental data, although the behaviour of Seebeck effect as a function of
doping demonstrates that a multiband description would be more appropriate. On
the contrary, experimental data of the Fe1+y(Te1-x,Sex) series exhibit a
strongly compensated behaviour, which can be described only within a multiband
model. In the Fe1+y(Te1-x,Sex) series, the role of the excess Fe, tuned by Se
stoichiometry, is found to be twofold: it dopes electrons in the system and it
introduces localized magnetic moments, responsible for Kondo like scattering
and likely pair-breaking of Cooper pairs. Hence, excess Fe plays a crucial role
also in determining superconducting properties such as the Tc and the upper
critical field Bc2. The huge Bc2 values of the Fe1+y(Te1-x,Sex) samples are
described by a dirty limit law, opposed to the clean limit behaviour of the
SmFeAs(O1-xFx) samples. Hence, magnetic scattering by excess Fe seems to drive
the system in the dirty regime, but its detrimental pairbreaking role seems not
to be as severe as predicted by theory. This issue has yet to be clarified,
addressing the more fundamental issue of the interplay between magnetism and
superconductivity
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