1,655 research outputs found
Formalism and Conserved Currents in Cosmology
The formalism, based on the counting of the number of e-folds
during inflation in different local patches of the Universe, has been
introduced several years ago as a simple and physically intuitive approach to
calculate (non-linear) curvature perturbations from inflation on large sales,
without resorting to the full machinery of (higher-order) perturbation theory.
Later on, it was claimed the equivalence with the results found by introducing
a conserved fully non-linear current , thereby allowing to directly
connect perturbations during inflation to late-Universe observables. We discus
some issues arising from the choice of the initial hyper-surface in the formalism. By using a novel exact expression for , valid for any
barotropic fluid, we find that it is not in general related to the standard
uniform density curvature perturbation ; such a result conflicts with
the claimed equivalence with formalism. Moreover, a similar analysis
is done for the proposed non-perturbative generalization of the
comoving curvature perturbation .Comment: 19 pages, 1 figures. Final version accepted for publication in JCAP.
Title slightly changed to avoid confusion with existing literature. Expanded
content with the same conclusion
«FU CHIAMATO ANALFABETO, COME QUASI NON HAVESSE IMPARATO Nà PUR L'ALFABETO». Storia della parola analfabeta (o analfabeto) e dei suoi derivati
This work traces the history of the word analfabeto. The latter represents the original form of the term, which appeared at the beginning of the 17th century, and which was first joined and then replaced by the anethymological form, analfabeta. This study outlines the history of a lexicographical ghost, whose origins are associated with Bonavilla (1807) before being handed down, through a series of quotations, to contemporary vocabularies. The history of the earliest attestations is reconstructed, including the confusion between Justinian and Justin characterising the earliest contexts as well as the communicative use of the word among scholars. In addition, the process of progressive substitution of analfabeto with analfabeta is observed by commenting on the point of view of nineteenth- and early twentieth-century dictionaries. Finally, this work reports on the events surrounding crucial issues such as the right to vote and legislative reforms, before reporting on the success story that is represented by the affirmation of the derivative analfabetismo
Resilience of long modes in cosmological observables
By a careful implementation of gauge transformations involving
long-wavelength modes, we show that a variety of effects involving squeezed
bispectrum configurations, for which one Fourier mode is much shorter than the
other two, cannot be gauged away, except for the unphysical exactly
infinite-wavelength () limit. Our result applies, in particular, to the
Maldacena consistency relation for single-field inflation, yielding a local
non-Gaussianity strength (with
the primordial spectral index of scalar perturbations), and to the term, appearing in the dark matter bispectrum and in the
halo bias, as a consequence of the general relativistic non-linear evolution of
matter perturbations. Such effects are therefore physical and observable in
principle by future high-sensitivity experiments.Comment: 19 pages, no figures. LaTex. Version accepted for publication in
JCAP, minor change
Exploring life forms for linking Orthopteran assemblage and grassland plant community:
AbstractOrthopterans are well known to represent the majority of insect biomass in many grassland ecosystems. However, the verification of a relationship between the traditional descriptors of orthopteran assemblage structure and plant community patterns is not straightforward. We explore the usefulness of the concept of life forms to provide insights on such ecosystem level relationship. For this purpose, thirty sample sites in semi-natural calcareous grasslands were classified according to the relative proportion of dominant herbaceous plant life forms. Orthopteran species were grouped in four categories, based on the Bei-Bienko's life form categorization. The association among plant communities, orthopteran assemblages and environmental factors was tested by means of canonical correspondence analysis. Orthoptera groups were found to be associated with distinct plant communities, also indicating the effect of vegetation change on orthopteran assemblages. In particular, geobionta species were associated with all the most disturbed plant communities, while chortobionta and thamnobionta seemed to be dependent on better preserved grassland types. Therefore, the use of life forms could help informing on the relationships of orthopteran assemblages with grassland conservation state. Information on such community relationships at the local scale could also assist managers in the interpretation of habitat change maps in terms of biodiversity changes
Thermoclastic and cryoclastic action on calcareous building stone: durability to artificial ageing
Short and long-term climate changes are a critical factor of stone decay even in temperate Mediterranean areas, when the combined fluctuations of temperature and moisture lead to thermoclastism and cryoclastism. The effects of weathering are of particular concern in the conservation field, for the assessment of the vulnerability of outdoorexposed stone materials in the historical built heritage. An example of this outline is Apulia, a region of southern Italy characterized by warm, dry summers and mild, rather rainy winters that can bring sub-zero temperatures; here, climate-driven decay can seriously affect the state of conservation of the local calcareous stone used in the monumental heritage, especially the most porous and softest materials. The dynamic behavior of the Apulian calcareous stone in response to thermo-hygrometric stresses was studied here by means of an artificial accelerated ageing test, focusing on a single local stone variety known as âpietra gentileâ. It is a fine-grained, soft and porous calcarenite, which is exploited in the Murge area from the outcrops of the âCalcare di Carannaâ Fm. (late Campanian?âMaastrichtian). The quarrying activity is concentrated in the territory of Valle dâItria and mainly of Ostuni, touristically known as âthe White Townâ, where the stone is widely used for the sacred and civil architecture. The ageing test was programmed according to the typical climatic characteristics of the considered area, following the historical recordings by the official Apulian monitoring institute (Struttura di Monitoraggio Meteoclimatico, Centro Funzionale Regionale); in order to simulate the seasonal climatic changes, the extreme temperatures were considered, while the possible insolation effects for higher temperatures were also taken into account. So, samples of âpietra gentileâ were subjected to 100 temperature cycles from 60 to â5 âŠC, in a climatic chamber with a maximum relative humidity of 60%. Before the ageing, the samples were petrographically characterized through optical microscopy on thin section, followed by a geotechnical parameterization with petrophysical measurements (dry density, total porosity, MIP porosity) and indirect ultrasonic and sclerometric tests. Then, after every 20 ageing cycles, the same tests stated above were carried out; in addition, the measurement of residual strains and SEM observations were performed. With this methodology, the gradual modifications in fabric, petrophysical and mechanical properties of the tested stone were analyzed.The results revealed a high durability of the material to the conditions of ageing experimented. The main modifications of the samples concerned fabric, i.e. microcracking due to thermoclastic and cryoclastic action, which occurred only in limited areas for an uneven distribution of internal stresses. For this reason, no evident effects on the macroscopic integrity and physico-mechanical performance were noted, whereas the stone almost preserved the original strength and elasticity. Finally, the data gathered were used to suggest a method for the evaluation of the vulnerability of âpietra gentileâ to freeze-thaw microcracking, based on the peculiar porosimetric distribution and the environmental conditions of weathering. New information are globally provided about a stone material that has been largely used in the Apulian monumental heritage, but has received scarce attention from the archaeometric research so far
Primordial Non-Gaussianity in Supersolid Inflation
We study primordial non-gaussianity in supersolid inflation. The dynamics of
supersolid is formulated in terms of an effective field theory based on four
scalar fields with a shift symmetric action minimally coupled with gravity. In
the scalar sector, there are two phonon-like excitations with a kinetic mixing
stemming from the completely spontaneous breaking of diffeomorphism. In a
squeezed configuration, of scalar perturbations is angle
dependent and not proportional to slow-roll parameters showing a blunt
violation of the Maldacena consistency relation. Contrary to solid inflation,
the violation persists even after an angular average and generically the amount
of non-gaussianity is significant. During inflation, non-gaussianity in the TSS
and TTS sector is enhanced in the same region of the parameters space where the
secondary production of gravitational waves is sizeable enough to enter in the
sensitivity region of LISA, while the scalar is still within
the current experimental limits.Comment: 54 pages, 13 figures. Latex file. A number of typos corrected with
the JHEP versio
The role of knowledge in water service coproduction and policy implications
More than 50 years after the seminal studies of Elinor Ostrom, the concept of water service âcoproductionâ is of interest due to its ability to achieve a delicate balance of governance in the sector. This novel analysis applies a systematic literature review to the water coproduction policies to identify the factors that promote their successful development. The results show that knowledge is the decisive element for newly shared governance. From this study, implications for water management and research are derived
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