183 research outputs found
An alternative perspective on projectivity of modules
Similar to the idea of relative projectivity, we introduce the notion of
relative subprojectivity, which is an alternative way to measure the
projectivity of a module. Given modules and , is said to be {\em
-subprojective} if for every epimorphism and
homomorphism , then there exists a homomorphism such that . For a module , the {\em subprojectivity
domain of } is defined to be the collection of all modules such that
is -subprojective. A module is projective if and only if its subprojectivity
domain consists of all modules. Opposite to this idea, a module is said to
be {\em subprojectively poor}, or {\em -poor} if its subprojectivity domain
is as small as conceivably possible, that is, consisting of exactly the
projective modules. Properties of subprojectivity domains and -poor modules
are studied. In particular, the existence of an -poor module is attained
for artinian serial rings.Comment: Dedicated to the memory of Francisco Raggi; v2 some editorial
changes. 'Right hereditary right perfect' replaced by the (equivalent)
condition 'right hereditary semiprimary'; v3 a mistake corrected in the
statements of Propositions 3.8 and 3.
A novel mutation in calcium-sensing receptor gene associated to hypercalcemia and hypercalciuria.
Background: Familial Hyperparathyroidism (HPT) and Familial benign Hypocalciuric Hypercalcemia (FHH) are the most common causes of hereditary hypercalcemia. FHH has been demonstrated to be caused by inactivating mutations of calcium-sensing receptor (CaSR) gene, involved in PTH regulation as well as in renal calcium excretion.Case presentation: In two individuals, father and son, we found a novel heterozygous mutation in CaSR gene. The hypercalcemia was present only in father, which, by contrast to the classic form of FHH showed hypercalciuria (from 300 to 600 mg/24 h in different evaluations) and a Calcium/Creatinine ratio of 0.031, instead of low or normal calciuria (<0.01 typical finding in FHH). His son showed the same mutation in CaSR gene, but no clinical signs or hypercalcemia although serum ionized calcium levels were close to the upper limit of normal values (1.30 mmol/L: normal range: 1.12-1.31 mmol/L). Sequence analysis revealed a point mutation at codon 972 of CaSR gene (chromosome 3q), located within cytoplasmic domain of the CaSR, that changes Threonine with Methionine. The father was treated with Cinacalcet 90 mg/day, with a decrease of total serum calcemia from an average value of 12.2 mg/dl to 10.9 mg/dl.Conclusion: This is a case of a novel inactivating point mutation of CaSR gene that determines an atypical clinical presentation of FHH, characterized by hypercalcemia, hypercalciuria and inadequate normal PTH levels. Functional assay demonstrated that the 972 M variant influenced the maturation of the protein, in terms of the post-translational glycosylation. The impairment of the receptor activity is in keeping with the specific localization of the 972 residue in the C-terminal tail, assigned to the intracellular signalling, that on the basis of the our findings appears to be differently modulated in parathyroid gland and in kidne
Beyond inverse Ising model: structure of the analytical solution for a class of inverse problems
I consider the problem of deriving couplings of a statistical model from
measured correlations, a task which generalizes the well-known inverse Ising
problem. After reminding that such problem can be mapped on the one of
expressing the entropy of a system as a function of its corresponding
observables, I show the conditions under which this can be done without
resorting to iterative algorithms. I find that inverse problems are local (the
inverse Fisher information is sparse) whenever the corresponding models have a
factorized form, and the entropy can be split in a sum of small cluster
contributions. I illustrate these ideas through two examples (the Ising model
on a tree and the one-dimensional periodic chain with arbitrary order
interaction) and support the results with numerical simulations. The extension
of these methods to more general scenarios is finally discussed.Comment: 15 pages, 6 figure
Piracy of scientific papers in Latin America: An analysis of Sci-Hub usage data
Sci-Hub hosts pirated copies of 51 million scientific papers from commercial publishers. This article presents the siteâs characteristics, it criticizes that it might be perceived as a de-facto component of the Open Access movement, it replicates an analysis published in Science using its available usage data, but limiting it to Latin America, and presents implications caused by this site for information professionals, universities and libraries
Cosmic ray knee and new physics at the TeV scale
We analyze the possibility that the cosmic ray knee appears at an energy
threshold where the proton-dark matter cross section becomes large due to new
TeV physics. It has been shown that such interactions could break the proton
and produce a diffuse gamma ray flux consistent with MILAGRO observations. We
argue that this hypothesis implies knees that scale with the atomic mass for
the different nuclei, as KASKADE data seem to indicate. We find that to explain
the change in the spectral index in the flux from E^{-2.7} to E^{-3.1} the
cross section must grow like E^{0.4+\beta} above the knee, where \beta=0.3-0.6
parametrizes the energy dependence of the age (\tau \propto E^{-\beta}) of the
cosmic rays reaching the Earth. The hypothesis also requires mbarn cross
sections (that could be modelled with TeV gravity) and large densities of dark
matter (that could be clumped around the sources of cosmic rays). We argue that
neutrinos would also exhibit a threshold at E=(m_\chi/m_p)E_{knee}\approx 10^8
GeV where their interaction with a nucleon becomes strong. Therefore, the
observation at ICECUBE or ANITA of standard neutrino events above this
threshold would disprove the scenario.Comment: 10 pages, version to appear in JCA
Managing head and neck cancer patients during the COVID-19 pandemic: the experience of a tertiary referral center in southern Italy
Individual Rights, Economic Transactions, and Recognition: A Legal Approach to Social Economics
Modernity brought the idea of individual property rights as a com- plex phenomenon. However, economics adopted a simplistic view of property as a fundamental institution, understating the complex interaction of different rights and obligations that frame the legal environment of economic processes with an insufficiently elaborated tool. Here, a more elaborate view of legal elements will be propose
Lay People Representations on the Common Good and Its Financial Provision
The financial contribution to the common good is a relevant issue to contemporary societies, especially in the wake of the Global Financial Crisis. In the economic literature, taxes and monetary donations have been regarded as two complementary ways of financially providing for the common good. In the psychological literature, instead, they have not been studied in conjunction. In-depth interviews have been conducted using interpretative phenomenological analysis (IPA) approach and a photo-elicitation technique to investigate the representations people share on the financial provision for the common good. Results suggest that both taxes and donations are seen as indirect, rather than direct, ways of providing for the common good. From a formal and cognitive level, paying taxes and making donations can be seen as two sides of the same coin, but they present differences at the affective level. When paying taxes, people are concerned mostly about the effects and expect a material exchange in return; when making a monetary donation, people are concerned mostly about the motivations and expect an emotional exchange in return
Self-interstitials injection in crystalline Ge induced by GeO 2 nanoclusters
The effect of O implantation in crystalline Ge on the density of native point defects has been investigated through transmission electron microscopy and B diffusion experiments. Annealing at 650 âą C following O implants produces a band of defects (âŒ5-10 nm), compatible with GeO 2 nanoclusters (NCs). A clear shape transformation from elongated to spherical forms occurs within 2 h, concomitant with a transient enhanced diffusion of B. A large injection of self-interstitials from GeO 2 NCs, giving a vacancy undersaturation, and a long-range migration of self-interstitials are evidenced and discussed
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