Rare-gas solids under pressure: A path-integral Monte Carlo simulation

Rare-gas solids (Ne, Ar, Kr, and Xe) under hydrostatic pressure up to 30 kbar have been studied by path-integral Monte Carlo simulations in the isothermal-isobaric ensemble. Results of these simulations have been compared with available experimental data and with those obtained from a quasiharmonic approximation (QHA). This comparison allows us to quantify the overall anharmonicity of the lattice vibrations and its influence on several structural and thermodynamic properties of rare-gas solids. The vibrational energy increases with pressure, but this increase is slower than that of the elastic energy, which dominates at high pressures. In the PIMC simulations, the vibrational kinetic energy is found to be larger than the corresponding potential energy, and the relative difference between both energies decreases as the applied pressure is raised. The accuracy of the QHA increases for rising pressure.Comment: 9 pages, 6 figure

A new outcome measure for cost-utility analyses of screening programs

We show that, under some plausible assumptions, the gain in QALYs a screening program offers is a positive linear transformation of the program's sensitivity level. This result simplifies considerably the cost-utility analysis of mutually exclusive screening programs.

Opportunity analysis of newborn screening programs

There exist congenital diseases that reduce newborns' potential opportunities. This reduction is sometimes alleviated if the congenital disease is early detected thanks to a newborn screening program. We propose an outcome measurement of newborn screening programs based on the opportunity gains they offer. We show that, under plausible assumptions, the ranking of the available screening programs for a particular disease, according to this new outcome measurement, do not depend on the metric of opportunity. We also apply our model to the current debate about choosing between a selective or a universal newborn hearing screening program to detect congenital hearing impairment.opportunities, potential success, screening programs

Molar volume of solid isotopic helium mixtures

Solid isotopic helium mixtures have been studied by path-integral Monte Carlo simulations in the isothermal-isobaric ensemble. This method allowed us to study the molar volume as a function of temperature, pressure, and isotopic composition. At 25 K and 0.2 GPa, the relative difference between molar volumes of isotopically-pure crystals of 3He and 4He is found to be about 3%. This difference decreases under pressure, and for 12 GPa it is smaller than 1%. For isotopically-mixed crystals, a linear relation between lattice parameters and concentrations of helium isotopes is found, in agreement with Vegard's law. The virtual crystal approximation, valid for isotopic mixtures of heavier atoms, does not give reliable results for solid solutions of helium isotopes.Comment: 7 pages, 5 figure

A NEW OUTCOME MEASURE FOR COST-UTILITY ANALYSES OF SCREENING PROGRAMS

In this paper we provide a new outcome measure for the cost-utility analyses of alternative screening programs of a particular disease. We show that for non-invasive screening programs satisfying plausible assumptions, QALYs can be replaced by a simpler outcome: the sensitivity of the program. In other words, the cost-utility analysis can be made without computing the utility each program offers. Consequently, results would be immune to two of the most controversial issues in the cost-utility analysis approach: the elicitation method to obtain quality weights of health profiles, and the discount rate for future health benefits. The assumptions are particularly suitable in the case of selecting between the universal and the selective implementation of a non-invasive screening program. Therefore, we apply our result to provide an additional viewpoint in the current debate about the implementation of a universal or selective newborn screening program to detect congenital hearing impairment.Cost-utility analysis, cost-sensitivity ratios, screening programs,

OPPORTUNITY ANALYSIS OF NEWBORN SCREENING PROGRAMS

There exist congenital diseases that reduce newborns' potential opportunities. This reduction is sometimes alleviated if the congenital disease is early detected thanks to a newborn screening program. We propose an outcome measurement of newborn screening programs based on the opportunity gains they offer after its implementation. We show that, under plausible assumptions, preferences among the available screening programs for a particular disease according to this new outcome measurement, do not depend on the metric of opportunity. We also apply our model to the current debate about choosing between a selective or a universal newborn hearing screening program to detect congenital hearing impairment.Opportunity analysis, potential success, screening programs

ECONOMIC EVALUATION OF NEWBORN HEARING SCREENING PROCEDURES

In the past few years, there has been a growing interest in the medical literature about the study of the different existing screening procedures to detect hearing impairment in infants and young children. However, concerning their economic evaluation, there are some important aspects, such as indirect costs, which are not considered by that literature. Here, we present an economic evaluation of these screening procedures, using utility theory, to measure benefits of a health care program, i.e. a cost-utility analysis. The analysis is presented from different points of view, depending on the cost we would like to compute. If we only consider direct costs, then targeted procedures, based on high risk criteria are preferred. On the other hand, if indirect costs, such as special education, and disability allowances were computed, then cost-utility analysis would advocate for the implementation of universal screening procedures.Economic Evaluation; Cost Utility Analysis; Cost-Sensitivity Ratios;

GENERALIZED COST-ANALYSIS OF SCREENING PROGRAMS

Nowadays, there is a growing interest about including indirect costs of health care programs in economic evaluations. In this paper, we provide a generalized cost-analysis of screening programs and propose a technique to measure production gains associated with these programs. We apply this technique to show evidence in favor of implementing a newborn screening program to detect congenital hearing impairment.Production gains, screening programs, cost analysis, potential social earnings.

Propagating, evanescent, and localized states in carbon nanotube-graphene junctions

We study the electronic structure of the junctions between a single graphene layer and carbon nanotubes, using a tight-binding model and the continuum theory based on Dirac fermion fields. The latter provides a unified description of different lattice structures with curvature, which is always localized at six heptagonal carbon rings around each junction. When these are evenly spaced, we find that it is possible to curve the planar lattice into armchair (6n,6n) as well as zig-zag (6n,0) nanotubes. We show that the junctions fall into two different classes, regarding the low-energy electronic behavior. One of them, constituted by the junctions made of the armchair nanotubes and the zig-zag (6n,0) geometries when n is a multiple of 3, is characterized by the presence of two quasi-bound states at the Fermi level, which are absent for the rest of the zig-zag nanotubes. These states, localized at the junction, are shown to arise from the effective gauge flux induced by the heptagonal carbon rings, which has a direct reflection in the local density of states around the junction. Furthermore, we also analyze the band structure of the arrays of junctions, finding out that they can also be classified into two different groups according to the low-energy behavior. In this regard, the arrays made of armchair and (6n,0) nanotubes with n equal to a multiple of 3 are characterized by the presence of a series of flat bands, whose number grows with the length of the nanotubes. We show that such flat bands have their origin in the formation of states confined to the nanotubes in the array. This is explained in the continuum theory from the possibility of forming standing waves in the mentioned nanotube geometries, as a superposition of modes with opposite momenta and the same quantum numbers under the C_6v symmetry of the junction.Comment: 13 pages, 8 figure

Populism and Precarity in Contemporary Indian Dystopian Fiction: Nayantara Sahgal''s When the Moon Shines By Day and Prayaag Akbar''s Leila

Although dystopia has been an enduring trope in literature, it is now, however, that dystopian and apocalyptic fiction has become especially popular all over the world. The main aim of this article is to discuss how contemporary Indian fiction denounces the barbarity of contemporary Indian nationalism, in particular the policies enforced by a repressive Indian state where tradition and purity are valued above multiculturality, dialogue and equality. In order to do this, I focus on two internationally acclaimed novels, namely, Nayantara Sahgal's When the Moon Shines by Day (2017) and Prayaag Akbar's Leila (2018). In different but complementary ways, both dystopias draw a telling portrait of precarious times in contemporary India. Both novels also warn against the dangers of the fundamentalist version of Hindu nationalism and cultural censorship, at the same time as they bring to our attention the damage that a dominant minority can inflict on those situated at the bottom of the social ladder, who are thus condemned to live in inhuman conditions, as if they were less than nothing