1,658 research outputs found
Productive Efficiency in 16 European Countries
We investigate in this paper differences in productive efficiency across sixteen European countries. In order to assess differences in productive efficiency, we have built a dynamic input-output model and computed for each country the balanced growth rate and the balanced output composition. After that, we investigate how the differences existing between the output composition for balanced growth and the actual one relate to the differences between the rate of balanced growth and the actual one. In the final part of the paper we examine the influence of individual sectors on the rate of balanced growth by looking for growth-sensitive sectors.Productive efficiency, input-output, growth, Europe
Breath of Life: Heart Disease Link to Developmental Hypoxia.
Heart disease remains one of the greatest killers. In addition to genetics and traditional lifestyle risk factors, we now understand that adverse conditions during pregnancy can also increase susceptibility to cardiovascular disease in the offspring. Therefore, the mechanisms by which this occurs and possible preventative therapies are of significant contemporary interest to the cardiovascular community. A common suboptimal pregnancy condition is a sustained reduction in fetal oxygenation. Chronic fetal hypoxia results from any pregnancy with increased placental vascular resistance, such as in preeclampsia, placental infection, or maternal obesity. Chronic fetal hypoxia may also arise during pregnancy at high altitude or because of maternal respiratory disease. This article reviews the short- and long-term effects of hypoxia on the fetal cardiovascular system, and the importance of chronic fetal hypoxia in triggering a developmental origin of future heart disease in the adult progeny. The work summarizes evidence derived from human studies as well as from rodent, avian, and ovine models. There is a focus on the discovery of the molecular link between prenatal hypoxia, oxidative stress, and increased cardiovascular risk in adult offspring. Discussion of mitochondria-targeted antioxidant therapy offers potential targets for clinical intervention in human pregnancy complicated by chronic fetal hypoxia.The work is supported by The British Heart Foundation (RG/17/8/32924) and the Medical Research Council UK (MR/V03362X/1)
Get Out the (Costly) Vote: Institutional Design for Greater Participation
Institutions designed to increase turnout appeal to democratic sentiments but are highly debated as they entail two potentially countervailing effects. While generating more pieces of information, they may decrease the average voter's information quality. We examine two commonly discussed institutions inducing participation: abstention penalties (used in 32 countries around the world) and lotteries providing a prize to one randomly chosen participant (as proposed on the 2006 Arizona ballot). We analyze a benchmark rational choice model in which voters vary in their information quality and participation is costly. We illustrate that both institutions can improve collective outcomes, though lotteries are a more effective instrument asymptotically. In an array of lab experiments we empirically assess institutional performance. We find strong evidence for selective participation: lab voters participate more when better informed or when institutionally induced. However, because subjects vote more often than the equilibrium predictions, these institutions entail less welfare benefits than theory prescribes. Lotteries do fare better than fines, suggesting that they may be a useful alternative to commonly used compulsory voting schemes.Costly voting; Election lotteries; Laboratory elections
The Bargiolina, a striking historical stone from Monte Bracco (Piedmont, NW Italy) and a possible source of industrial minerals
The Bargiolina quartzite from Monte Bracco (western Alps, northern Italy) represents one of the most important historical ornamental stones of the Piedmont region. Known and used since the prehistoric age as substituting material for chert, it was celebrated by Leonardo da Vinci, and exploited at least since the XIII century, peaking in the XX century. It was extensively used in the construction of basilicas and noble palaces by famous architects of Piedmontese Baroque, for internal and external stone cladding. There are four main commercial and chromatic varieties, and the main technical feature is the regular schistosity, to obtain very thin natural split slabs. The different varieties have a homogeneous mineralogical composition and microstructure: A fine and homeoblastic grain size, and a granular—lepidoblastic texture, with regularly spaced schistose domains. The main rock-forming minerals are quartz, phengite, small amounts of K-feldspar and traces of plagioclase and chlorite. The yield rate of quarries is about 20%, and the poor exploitation planning of the past led to only partly exploited quarry benches, with a very poor residual yield. The large amount of quartz-rich quarry waste and the presence of kaolin-rich gneisses suggests the potential for novel applications in the field of industrial minerals
Integrating the geodesic equations in the Schwarzschild and Kerr space-times using Beltrami's "geometrical" method
We revisit a little known theorem due to Beltrami, through which the
integration of the geodesic equations of a curved manifold is accomplished by a
method which, even if inspired by the Hamilton-Jacobi method, is purely
geometric. The application of this theorem to the Schwarzschild and Kerr
metrics leads straightforwardly to the general solution of their geodesic
equations. This way of dealing with the problem is, in our opinion, very much
in keeping with the geometric spirit of general relativity. In fact, thanks to
this theorem we can integrate the geodesic equations by a geometrical method
and then verify that the classical conservation laws follow from these
equations.Comment: 12 pages; corrected typos, journal-ref adde
Methodology for Pressurized Thermal Shock Analysis in Nuclear Power Plant
The relevance of the fracture mechanics in the technology of the nuclear power plant is
mainly connected to the risk of a catastrophic brittle rupture of the reactor pressure vessel.
There are no feasible countermeasures that can mitigate the effects of such an event that
impair the capability to maintain the core covered even in the case of properly functioning
of the emergency systems.
The origin of the problem is related to the aggressive environment in which the vessel
operates for long term (e.g. more than 40 years), characterized by high neutron flux during
normal operation. Over time, the vessel steel becomes progressively more brittle in the
region adjacent to the core. If a vessel had a preexisting flaw of critical size and certain
severe system transients occurred, this flaw could propagate rapidly through the vessel,
resulting in a through-wall crack. The severe transients that can lead the nuclear power
plant in such conditions, known as Pressurized Thermal Shock (PTS), are characterized by
rapid cooling (i.e., thermal shock) of the a part of the internal reactor pressure vessel surface
that may be combined with repressurization can create locally a sudden increase of the
stresses inside the vessel wall and lead to the suddenly growth of the flaw inside the vessel
thickness.
Based on the long operational experience from nuclear power plants equipped with reactor
pressure vessel all over the world, it is possible to conclude that the simultaneous
occurrence of critical-size flaws, embrittled vessel, and a severe PTS transient is a very low
probability event. Moreover, additional studies performed at utilities and regulatory
authorities levels have shown that the RPV can operate well beyond the original design life
(40 years) because of the large safety margin adopted in the design phase.
A better understanding and knowledge of the materials behavior, improvement in
simulating in a more realistic way the plant systems and operational characteristics and a better evaluation of the loads on the RPV wall during the PTS scenarios, have shown that
the analysis performed during the 80’s were overly conservative, based on the tools and
knowledge available at that time.
Nowadays the use of best estimate approach in the analyses, combined with tools for the
uncertainty evaluation is taking more consideration to reduce the safety margins, even from
the regulatory point of view. The US NRC has started the process to revise the technical base
of the PTS analysis for a more risk-informed oriented approach. This change has the aim to
remove the un-quantified conservatisms in all the steps of the PTS analysis, from the
selection of the transients, the adopted codes and the criteria for conducting the analysis
itself thus allow a more realistic prediction.
This change will not affect the safety, because beside the operational experience, several
analysis performed by thermal hydraulic, fracture mechanics and Probabilistic Safety
Assessment (PSA) point of view, have shown that the reactor fleet has little probability of
exceeding the limits on the frequency of reactor vessel failure established from NRC
guidelines on core damage frequency and large early release frequency through the period
of license extension. These calculations demonstrate that, even through the period of license
extension, the likelihood of vessel failure attributable to PTS is extremely low (≈10-8/year)
for all domestic pressurized water reactors.
Different analytical approaches have been developed for the evaluation of the safety margin
for the brittle crack propagation in the rector pressure vessel under PTS conditions. Due to
the different disciplines involved in the analysis: thermal-hydraulics, structural mechanics
and fracture mechanics, different specialized computer codes are adopted for solving single
part of the problem.
The aims of this chapter is to present all the steps of a typical PTS analysis base on the
methodology developed at University of Pisa with discussion and example calculation
results for each tool adopted and their use, based on a more realistic best estimate approach.
This methodology starts with the analysis of the selected scenario by mean a System
Thermal-Hydraulic (SYS-TH) code such as RELAP5 [2][3], RELAP5-3D [1], CATHARE2
[4][6], etc. for the analysis of the global behavior of the plant and for the evaluation of the
primary side pressure and fluid temperature at the down-comer inlet.
For a more deep investigation of the cooling load on the rector pressure vessel internal
surface at small scale, a Computational Fluid Dynamics (CFD) code is used. The calculated
temperature profile in the down-comer region is transferred to a Finite Element (FE)
structural mechanics code for the evaluation of the stresses inside the RPV wall. The stresses
induced by the pressure in the primary side are also evaluated.
The stress intensity factor at crack tip is evaluated by mean the weight function method
based on a simple integration of the stresses along the crack border multiplied by the weight
function. The values obtained are compared with the critical stress intensity factor typical of
the reactor pressure vessel base material for the evaluation of the safety margin
A point mutation in the splice donor site of intron 7 in the as2-casein encoding gene of the Mediterranean River buffalo results in an allele-specific exon skipping
The CSN1S2 cDNA of 10 unrelated Mediterranean
River Buffaloes reared in Southern Italy was amplified
by RT-PCR, while the region from the 6th to the 8th exon
of the CSN1S2 gene was amplified from genomic template.
cDNA sequence comparisons showed
that five individuals had a normal transcript only (named CSN1S2A), one had a
deleted transcript only (named CSN1S2B), because of the splicing out of the 27-bp of
exon 7, and the remaining four had a heterozygous pattern.
Analysis of the genomic sequences revealed a FM865620:
g.773G>C transversion that caused inactivation of the intron 7
splice donor site and, consequently, the allele-specific exon skipping
characteristic of the CSN1S2B allele. The g.773G>C
mutation creates a new AluI restriction site enabling a PCR–
RFLP rapid genotyping assay. The cDNA sequences showed three additional
exonic mutations forming an extended haplotype with
the g.773G>C polymorphism: FM865618: c.459C>T,
c.484A>T and c.568A>G homozygous and heterozygous
respectively in the CSN1S2BB and CSN1S2AB buffaloes. The
first is silent, while the remaining two are non-conservative
(p.Ile162Phe and p.Thp200Ala respectively). The genotype frequencies (37 CSN1S2A/A,
15 CSN1S2A/B and one CSN1S2B/B) are in agreement with
Hardy–Weinberg equilibrium, with the
frequency of the deleted B allele being 0.16.
The predicted bubaline as2B protein
is 198 aa long instead of 207 aa and would also be characterized
by the presence of Phe at position 147 and Ala at 185
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