3,756 research outputs found
Introduction to the special issue on institutions and culture in economic contexts
The need of further research on the interlink between culture and institutions has been strongly advocated by economists and institutionalists alike. However, bringing together culture and institutions within an organic framework, though, is a non-trivial operation. This is due to the complexity of the synergies between cultural aspects and institutional devices. This special issue attempts to start filling this gap and to build an ad-hoc systemic platform for disseminating such a debate. To this purpose, it brings together an organic collection of contributions in well-established conceptualisations of both culture and institutions, supported by robust and consistent methodological applications. The essays presented in this work provide consistent evidence and conceptual perspectives supporting the idea that the synergies between cultural and institutional aspects are of paramount importance to understand human behaviour, individuals' choices and societies' patterns. They also improve the theoretical, empirical and methodological understanding of the role of institutions and culture in different geopolitical and socio-economic realms. By doing so, these contributions place this special issue as prelude to further research on the co-evolution of culture and institutions and on its possible implications on different societal aspects, human development and well-being
Accurate evolutions of inspiralling and magnetized neutron-stars: equal-mass binaries
By performing new, long and numerically accurate general-relativistic
simulations of magnetized, equal-mass neutron-star binaries, we investigate the
role that realistic magnetic fields may have in the evolution of these systems.
In particular, we study the evolution of the magnetic fields and show that they
can influence the survival of the hypermassive-neutron star produced at the
merger by accelerating its collapse to a black hole. We also provide evidence
that even if purely poloidal initially, the magnetic fields produced in the
tori surrounding the black hole have toroidal and poloidal components of
equivalent strength. When estimating the possibility that magnetic fields could
have an impact on the gravitational-wave signals emitted by these systems
either during the inspiral or after the merger we conclude that for realistic
magnetic-field strengths B<~1e12 G such effects could be detected, but only
marginally, by detectors such as advanced LIGO or advanced Virgo. However,
magnetically induced modifications could become detectable in the case of
small-mass binaries and with the development of gravitational-wave detectors,
such as the Einstein Telescope, with much higher sensitivities at frequencies
larger than ~2 kHz.Comment: 18 pages, 10 figures. Added two new figures (figures 1 and 7). Small
modifications to the text to match the version published on Phys. Rev.
Accurate numerical simulations of inspiralling binary neutron stars and their comparison with effective-one-body analytical models
Binary neutron-star systems represent one of the most promising sources of
gravitational waves. In order to be able to extract important information,
notably about the equation of state of matter at nuclear density, it is
necessary to have in hands an accurate analytical model of the expected
waveforms. Following our recent work, we here analyze more in detail two
general-relativistic simulations spanning about 20 gravitational-wave cycles of
the inspiral of equal-mass binary neutron stars with different compactnesses,
and compare them with a tidal extension of the effective-one-body (EOB)
analytical model. The latter tidally extended EOB model is analytically
complete up to the 1.5 post-Newtonian level, and contains an analytically
undetermined parameter representing a higher-order amplification of tidal
effects. We find that, by calibrating this single parameter, the EOB model can
reproduce, within the numerical error, the two numerical waveforms essentially
up to the merger. By contrast, analytical models (either EOB, or Taylor-T4)
that do not incorporate such a higher-order amplification of tidal effects,
build a dephasing with respect to the numerical waveforms of several radians.Comment: 25 pages, 17 figs. Matched published versio
Accurate evolutions of inspiralling neutron-star binaries: assessment of the truncation error
We have recently presented an investigation in full general relativity of the
dynamics and gravitational-wave emission from binary neutron stars which
inspiral and merge, producing a black hole surrounded by a torus (see
arXiv:0804.0594). We here discuss in more detail the convergence properties of
the results presented in arXiv:0804.0594 and, in particular, the deterioration
of the convergence rate at the merger and during the survival of the merged
object, when strong shocks are formed and turbulence develops. We also show
that physically reasonable and numerically convergent results obtained at
low-resolution suffer however from large truncation errors and hence are of
little physical use. We summarize our findings in an "error budget", which
includes the different sources of possible inaccuracies we have investigated
and provides a first quantitative assessment of the precision in the modelling
of compact fluid binaries.Comment: 13 pages, 5 figures. Minor changes to match published version. Added
figure 5 right pane
Accurate evolutions of inspiralling neutron-star binaries: prompt and delayed collapse to black hole
Binary neutron-star (BNS) systems represent primary sources for the
gravitational-wave (GW) detectors. We present a systematic investigation in
full GR of the dynamics and GW emission from BNS which inspiral and merge,
producing a black hole (BH) surrounded by a torus. Our results represent the
state of the art from several points of view: (i) We use HRSC methods for the
hydrodynamics equations and high-order finite-differencing techniques for the
Einstein equations; (ii) We employ AMR techniques with "moving boxes"; (iii) We
use as initial data BNSs in irrotational quasi-circular orbits; (iv) We exploit
the isolated-horizon formalism to measure the properties of the BHs produced in
the merger; (v) Finally, we use two approaches, based either on gauge-invariant
perturbations or on Weyl scalars, to calculate the GWs. These techniques allow
us to perform accurate evolutions on timescales never reported before (ie ~30
ms) and to provide the first complete description of the inspiral and merger of
a BNS leading to the prompt or delayed formation of a BH and to its ringdown.
We consider either a polytropic or an ideal fluid EOS and show that already
with this idealized EOSs a very interesting phenomenology emerges. In
particular, we show that while high-mass binaries lead to the prompt formation
of a rapidly rotating BH surrounded by a dense torus, lower-mass binaries give
rise to a differentially rotating NS, which undergoes large oscillations and
emits large amounts of GWs. Eventually, also the NS collapses to a rotating BH
surrounded by a torus. Finally, we also show that the use of a non-isentropic
EOS leads to significantly different evolutions, giving rise to a delayed
collapse also with high-mass binaries, as well as to a more intense emission of
GWs and to a geometrically thicker torus.Comment: 35 pages, 29 figures, corrected few typos to match the published
version. High-resolution figures and animations can be found at
http://numrel.aei.mpg.de/Visualisations/Archive/BinaryNeutronStars/Relativistic_Meudon/index.htm
High Levels of Circulating Type II Collagen Degradation Marker (CTx-II) Are Associated with Specific VDR Polymorphisms in Patients with Adult Vertebral Osteochondrosis
Both vitamin D and collagen have roles in osteocartilaginous homeostasis. We evaluated the association between the circulating 25-hydroxyvitamin D (25(OH)D) type I and II collagen degradation products (CTx-I, and CTx-II), and four vitamin D receptor gene (VDR) polymorphisms, in Italian males affected by low back pain (LBP) due to herniation/discopathy and/or vertebral osteochondrosis. FokI, BsmI, ApaI, and TaqI VDR-polymorphisms were detected through PCR-restriction fragment length polymorphism (RFLP), and circulating 25(OH)D, CTx-I and CTx-II were measured by immunoassays in 79 patients (of which 26 had osteochondrosis) and 79 age-, sex- and body mass index (BMI)-matched healthy controls. Among all 158 subjects, carriers of FF and Ff genotypes showed lower 25(OH)D than ff, which suggested a higher depletion of vitamin D in F allele carriers. Higher CTx-I concentrations were observed in TT versus Tt among controls, and Tt versus tt among LBP cases, which suggested a higher bone-cartilaginous catabolism in subjects bearing the T allele. Higher CTx-II concentrations were observed in patients with osteochondrosis bearing FF, bb, TT, or Aa genotypes in comparison with hernia/discopathy patients and healthy controls. Vertebral osteochondrosis shows peculiar genotypic and biochemical features related to vitamin D and the osteocartilaginous metabolism. Vitamin D has roles in the pathophysiology of osteochondrosis
Perioperative management of hypertensive neuroblastoma: A study from the Italian Group of Pediatric Surgical Oncologists (GICOP)
Background: Hypertension (HT) is rarely reported in patients affected by Neuroblastoma (NB), and management guidelines are lacking. Clinical features and perioperativemedical treatment insuchpatientswere reviewed to1) ascertain whether a shared treatment strategy exists among centers and 2) if possible, propose some recommendations for the perioperative management of HT in NB patients.
Methods: A retrospectivemulticenter surveywas conducted on patients affected by NBwho presented HT symptoms.
Results: From 2006 to 2014, 1126 children were registered in the Italian Registry of Neuroblastoma (RINB). Of these, 21 with HT (1.8%) were included in our analysis. Pre- and intraoperative HT management was somewhat dissimilar among the participating centers, apart from a certain consistency in the intraoperative use of the alpha-1 blocker urapidil. Six of the 21 patients (28%) needed persistent antihypertensive treatment at a median follow-up of 36 months (range 4\u2013-96 months) despite tumor removal. Involvement of the renal pedicle was the only risk factor constantly associated to HT persistency following surgery. A correlation between the presence of HT and the secretion of specific catecholamines and/or compression of the renal vascular pedicle could not be demonstrated.
Conclusion: Based on this retrospective review of NB patients with HT, no definite therapeutic protocol can be recommended owing to heterogeneity of adopted treatments in different centers. A proposal of perioperative HT management in NB patients is however presented. Level of evidence: IV
Deficits in mitochondrial TCA cycle and OXPHOS precede rod photoreceptor degeneration during chronic HIF activation
Background: Major retinal degenerative diseases, including age-related macular degeneration, diabetic retinopathy and retinal detachment, are associated with a local decrease in oxygen availability causing the formation of hypoxic areas affecting the photoreceptor (PR) cells. Here, we addressed the underlying pathological mechanisms of PR degeneration by focusing on energy metabolism during chronic activation of hypoxia-inducible factors (HIFs) in rod PR.
Methods: We used two-photon laser scanning microscopy (TPLSM) of genetically encoded biosensors delivered by adeno-associated viruses (AAV) to determine lactate and glucose dynamics in PR and inner retinal cells. Retinal layer-specific proteomics, in situ enzymatic assays and immunofluorescence studies were used to analyse mitochondrial metabolism in rod PRs during chronic HIF activation.
Results: PRs exhibited remarkably higher glycolytic flux through the hexokinases than neurons of the inner retina. Chronic HIF activation in rods did not cause overt change in glucose dynamics but an increase in lactate production nonetheless. Furthermore, dysregulation of the oxidative phosphorylation pathway (OXPHOS) and tricarboxylic acid (TCA) cycle in rods with an activated hypoxic response decelerated cellular anabolism causing shortening of rod photoreceptor outer segments (OS) before onset of cell degeneration. Interestingly, rods with deficient OXPHOS but an intact TCA cycle did not exhibit these early signs of anabolic dysregulation and showed a slower course of degeneration.
Conclusion: Together, these data indicate an exceeding high glycolytic flux in rods and highlight the importance of mitochondrial metabolism and especially of the TCA cycle for PR survival in conditions of increased HIF activity
An improved formulation of the relativistic hydrodynamics equations in 2D Cartesian coordinates
A number of astrophysical scenarios possess and preserve an overall
cylindrical symmetry also when undergoing a catastrophic and nonlinear
evolution. Exploiting such a symmetry, these processes can be studied through
numerical-relativity simulations at smaller computational costs and at
considerably larger spatial resolutions. We here present a new
flux-conservative formulation of the relativistic hydrodynamics equations in
cylindrical coordinates. By rearranging those terms in the equations which are
the sources of the largest numerical errors, the new formulation yields a
global truncation error which is one or more orders of magnitude smaller than
those of alternative and commonly used formulations. We illustrate this through
a series of numerical tests involving the evolution of oscillating spherical
and rotating stars, as well as shock-tube tests.Comment: 19 pages, 9 figure
Dasabuvir and Ombitasvir/Paritaprevir/Ritonavir with or without Ribavirin in Patients with HIV-HCV Coinfection. Real Life Interim Analysis of an Italian Multicentre Compassionate Use Program
Background and Aims: An HCV cure is now possible in a large proportion of HIV-HCV patient. We present real life results of a compassionate use program promoted by SIMIT (Infectious and Tropical Diseases Italian Society) of Dasabuvir and Ombitasvir/Paritaprevir/Ritonavir ± Ribavirin for 12 weeks in 213 HIV-HCV genotype 1 patients. Data on efficacy and tolerability of this strategy in HIV patients have been reported until now only in 43 non cirrhotic HIV subjects
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