Spectra of dynamical Dark Energy cosmologies from constant-w models

WMAP5 and related data have greatly restricted the range of acceptable cosmologies, by providing precise likelihood ellypses on the the w_0-w_a plane. We discuss first how such ellypses can be numerically rebuilt, and present then a map of constant-w models whose spectra, at various redshift, are expected to coincide with acceptable models within ~1%

Sample variance in N--body simulations and impact on tomographic shear predictions

We study the effects of sample variance in N--body simulations, as a function of the size of the simulation box, namely in connection with predictions on tomographic shear spectra. We make use of a set of 8 $\Lambda$CDM simulations in boxes of 128, 256, 512 $h^{-1}$Mpc aside, for a total of 24, differing just by the initial seeds. Among the simulations with 128 and 512 $h^{-1}$Mpc aside, we suitably select those closest and farthest from {\it average}. Numerical and linear spectra $P(k,z)$ are suitably connected at low $k$ so to evaluate the effects of sample variance on shear spectra $C_{ij}(\ell)$ for 5 or 10 tomographic bands. We find that shear spectra obtained by using 128 $h^{-1}$Mpc simulations can vary up to $\sim 25\, \%$, just because of the seed. Sample variance lowers to $\sim 3.3\, \%$, when using 512 $h^{-1}$Mpc. These very percentages could however slightly vary, if other sets of the same number of realizations were considered. Accordingly, in order to match the $\sim 1\, \%$ precision expected for data, if still using 8 boxes, we require a size $\sim 1300$ --$1700 \, h^{-1}$ Mpc for them.Comment: accepted by Ap

Twilight of the Grrrls: Stephenie Meyer’s Rehash of the Feminine Mystique

In spite of the abundance of powerful female leads in recent media productions, Stephenie Meyer’s Twilight saga (2005-2008) signaled a relapse into the ideology of the feminine mystique, famously addressed in Betty Friedan's eponymous volume (1963). By analyzing Meyer's portrayal of protagonist Bella Swan's utter lack of agency, this paper explores the ways in which the saga rehashes and perpetuates an age-old Weltanschauung in which women find their natural self-fulfillment through marriage and motherhood, using the generic conventions of supernatural romance to reinforce beliefs based on female submission, on what Jessica Valenti defines as The Purity Myth (2009) and on America's post-9/11 revival of the rhetoric of male heroism (Susan Faludi, The Terror Dream, 2007)

Tomographic weak lensing shear spectra from large N-body and hydrodynamical simulations

Forthcoming experiments will enable us to determine tomographic shear spectra at a high precision level. Most predictions about them have until now been biased on algorithms yielding the expected linear and non-linear spectrum of density fluctuations. Even when simulations have been used, so-called Halofit (Smith et al 2003) predictions on fairly large scales have been needed. We wish to go beyond this limitation. We perform N-body and hydrodynamical simulations within a sufficiently large cosmological volume to allow a direct connection between simulations and linear spectra. While covering large length-scales, the simulation resolution is good enough to allow us to explore the high-l harmonics of the cosmic shear (up to l ~ 50000), well into the domain where baryon physics becomes important. We then compare shear spectra in the absence and in presence of various kinds of baryon physics, such as radiative cooling, star formation, and supernova feedback in the form of galactic winds. We distinguish several typical properties of matter fluctuation spectra in the different simulations and test their impact on shear spectra. We compare our outputs with those obtainable using approximate expressions for non--linear spectra, and identify substantial discrepancies even between our results and those of purely N-body results. Our simulations and the treatment of their outputs however enable us, for the first time, to obtain shear results taht are fully independent of any approximate expression, also in the high-l range, where we need to incorporate a non-linear power spectrum of density perturbations, and the effects of baryon physics. This will allow us to fully exploit the cosmological information contained in future high--sensitivity cosmic shear surveys, exploring the physics of cosmic shears via weak lensing measurements.Comment: 13 pages, 19 figures, A&A in pres

Extending the Coyote emulator to dark energy models with standard w0w_0-waw_a parametrization of the equation of state

We discuss an extension of the Coyote emulator to predict non-linear matter power spectra of dark energy (DE) models with a scale factor dependent equation of state of the form w = w_0 + ( 1 - a )w_a . The extension is based on the mapping rule between non-linear spectra of DE models with constant equation of state and those with time varying one originally introduced in ref. [40]. Using a series of N-body simulations we show that the spectral equivalence is accurate to sub-percent level across the same range of modes and redshift covered by the Coyote suite. Thus, the extended emulator provides a very efficient and accurate tool to predict non-linear power spectra for DE models with w_0 - w_a parametrization. According to the same criteria we have developed a numerical code, and we have implemented in a dedicated module for the CAMB code, that can be used in combination with the Coyote Emulator in likelihood analyses of non-linear matter power spectrum measurements. All codes can be found at https://github.com/luciano-casarini/PKequalComment: All codes can be found at https://github.com/luciano-casarini/PKequa

Towards a quieter world : three-dimensional printed acoustic metamaterials for noise control

Environmental noise impacts the everyday life of millions of people and it represents a growing concern for the health of the world's population. To mitigate this impact, noise reducing materials such as foam or barriers are employed extensively with effective results. However, the efficacy of such materials is limited by the inverse relationship between the frequency of the attenuated waves and materials characteristics like thickness and density, as described by the mass-law. In order to overcome this fundamental limitation, a new challenge in acoustic engineering has emerged to design and manufacture lightweight and subwavelength materials that can break the mass-law. A potential solution to this challenge is represented by a recently discovered family of materials, called acoustic metamaterials, which show properties typically not found in nature. These materials are made of resonant building blocks that are smaller than the wavelength of the attenuated acoustic wave. When these building blocks are combined to form a metamaterial, they lead to the formation of band gaps - near their resonance frequency - that deeply attenuate the incident sound. The manufacturing of noise reducing acoustic metamaterials could also largely benefit from recent advances in three-dimensional printing technologies, as they offer the possibility to fabricate abstract shapes and to carefully choose some properties of the printed materials. The work presented in this thesis describes the modelling, fabrication and measurement of noise reducing acoustic metamaterials based on Helmholtz resonators, thin plates and active piezoelectric plates. These materials have been produced through original and innovative three-dimensional printing techniques. The results of this thesis can be applied to noise control in audio applications such as headphones, hearing aids and smart speakers. Similarly, other fields like aerospace and automotive industry or architectural acoustics could also greatly benefit from lightweight subwavelength noise reduction.Environmental noise impacts the everyday life of millions of people and it represents a growing concern for the health of the world's population. To mitigate this impact, noise reducing materials such as foam or barriers are employed extensively with effective results. However, the efficacy of such materials is limited by the inverse relationship between the frequency of the attenuated waves and materials characteristics like thickness and density, as described by the mass-law. In order to overcome this fundamental limitation, a new challenge in acoustic engineering has emerged to design and manufacture lightweight and subwavelength materials that can break the mass-law. A potential solution to this challenge is represented by a recently discovered family of materials, called acoustic metamaterials, which show properties typically not found in nature. These materials are made of resonant building blocks that are smaller than the wavelength of the attenuated acoustic wave. When these building blocks are combined to form a metamaterial, they lead to the formation of band gaps - near their resonance frequency - that deeply attenuate the incident sound. The manufacturing of noise reducing acoustic metamaterials could also largely benefit from recent advances in three-dimensional printing technologies, as they offer the possibility to fabricate abstract shapes and to carefully choose some properties of the printed materials. The work presented in this thesis describes the modelling, fabrication and measurement of noise reducing acoustic metamaterials based on Helmholtz resonators, thin plates and active piezoelectric plates. These materials have been produced through original and innovative three-dimensional printing techniques. The results of this thesis can be applied to noise control in audio applications such as headphones, hearing aids and smart speakers. Similarly, other fields like aerospace and automotive industry or architectural acoustics could also greatly benefit from lightweight subwavelength noise reduction

The polycystic ovary syndrome evolutionary paradox: a genome-wide association studies-based, in silico, evolutionary explanation.

Objective: In this study we analyze the PCOS phenotype-genotype relationship in silico, using SNPs of representative genes for analysis of genetic clustering and distance, to evaluate the degree of genetic similarity. Data Source: 1000 Genomes, HapMap, and Human Genome Diversity Project databases were used as source of allele frequencies of the SNPs, using data from male and female individuals grouped according to their geographical ancestry. Setting and Design: Genetic clustering was calculated from SNPs data by Bayesian inference. The inferred ancestry of individuals was matched with PCOS phenotype data, extracted from a previous meta-analysis. The measure of genetic distance was plotted against the geographic distance between the populations. Results: The individuals were assigned to five genetic clusters, matching with different world regions (Kruskal-Wallis/Dunn's post test; P < .0001), and converging in two main PCOS phenotypes in different degrees of affinity. The overall genetic distance increased with the geographic distance among the populations (linear regression; R2 = 0.21; P < .0001), in a phenotype-unrelated manner. Conclusions: Phenotype-genotype correlations were demonstrated, suggesting that PCOS genetic gradient results from genetic drift due to a serial founder effect occurred during ancient human migrations. The overall prevalence of the disease supports intralocus sexual conflict as alternative to the natural selection of phenotypic traits in females