199 research outputs found
f(R) theories
Over the past decade, f(R) theories have been extensively studied as one of
the simplest modifications to General Relativity. In this article we review
various applications of f(R) theories to cosmology and gravity - such as
inflation, dark energy, local gravity constraints, cosmological perturbations,
and spherically symmetric solutions in weak and strong gravitational
backgrounds. We present a number of ways to distinguish those theories from
General Relativity observationally and experimentally. We also discuss the
extension to other modified gravity theories such as Brans-Dicke theory and
Gauss-Bonnet gravity, and address models that can satisfy both cosmological and
local gravity constraints.Comment: 156 pages, 14 figures, Invited review article in Living Reviews in
Relativity, Published version, Comments are welcom
Perspectives and Integration in SOLAS Science
Why a chapter on Perspectives and Integration in SOLAS Science in this book? SOLAS science by its nature deals with interactions that occur: across a wide spectrum of time and space scales, involve gases and particles, between the ocean and the atmosphere, across many disciplines including chemistry, biology, optics, physics, mathematics, computing, socio-economics and consequently interactions between many different scientists and across scientific generations. This chapter provides a guide through the remarkable diversity of cross-cutting approaches and tools in the gigantic puzzle of the SOLAS realm.
Here we overview the existing prime components of atmospheric and oceanic observing systems, with the acquisition of ocean–atmosphere observables either from in situ or from satellites, the rich hierarchy of models to test our knowledge of Earth System functioning, and the tremendous efforts accomplished over the last decade within the COST Action 735 and SOLAS Integration project frameworks to understand, as best we can, the current physical and biogeochemical state of the atmosphere and ocean commons. A few SOLAS integrative studies illustrate the full meaning of interactions, paving the way for even tighter connections between thematic fields. Ultimately, SOLAS research will also develop with an enhanced consideration of societal demand while preserving fundamental research coherency.
The exchange of energy, gases and particles across the air-sea interface is controlled by a variety of biological, chemical and physical processes that operate across broad spatial and temporal scales. These processes influence the composition, biogeochemical and chemical properties of both the oceanic and atmospheric boundary layers and ultimately shape the Earth system response to climate and environmental change, as detailed in the previous four chapters. In this cross-cutting chapter we present some of the SOLAS achievements over the last decade in terms of integration, upscaling observational information from process-oriented studies and expeditionary research with key tools such as remote sensing and modelling.
Here we do not pretend to encompass the entire legacy of SOLAS efforts but rather offer a selective view of some of the major integrative SOLAS studies that combined available pieces of the immense jigsaw puzzle. These include, for instance, COST efforts to build up global climatologies of SOLAS relevant parameters such as dimethyl sulphide, interconnection between volcanic ash and ecosystem response in the eastern subarctic North Pacific, optimal strategy to derive basin-scale CO2 uptake with good precision, or significant reduction of the uncertainties in sea-salt aerosol source functions. Predicting the future trajectory of Earth’s climate and habitability is the main task ahead. Some possible routes for the SOLAS scientific community to reach this overarching goal conclude the chapter
Multi-messenger observations of a binary neutron star merger
On 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of ~1.7 s with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg2 at a luminosity distance of 40+8-8 Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to 2.26 Mo. An extensive observing campaign was launched across the electromagnetic spectrum leading to the discovery of a bright optical transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC 4993 (at ~40 Mpc) less than 11 hours after the merger by the One- Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The optical transient was independently detected by multiple teams within an hour. Subsequent observations targeted the object and its environment. Early ultraviolet observations revealed a blue transient that faded within 48 hours. Optical and infrared observations showed a redward evolution over ~10 days. Following early non-detections, X-ray and radio emission were discovered at the transient’s position ~9 and ~16 days, respectively, after the merger. Both the X-ray and radio emission likely arise from a physical process that is distinct from the one that generates the UV/optical/near-infrared emission. No ultra-high-energy gamma-rays and no neutrino candidates consistent with the source were found in follow-up searches. These observations support the hypothesis that GW170817 was produced by the merger of two neutron stars in NGC4993 followed by a short gamma-ray burst (GRB 170817A) and a kilonova/macronova powered by the radioactive decay of r-process nuclei synthesized in the ejecta
Long-term use of non-steroidal anti-inflammatory drugs and the risk of myocardial infarction in the general population
BACKGROUND: Recent data indicate that chronic use of coxibs leads to an increased occurrence of thrombotic cardiovascular events. This raises the question as to whether traditional non-steroidal anti-inflammatory drugs (tNSAIDs) might also produce similar hazards. Our aim has been to evaluate the association between the chronic use of tNSAIDs and the risk of myocardial infarction (MI) in patients. METHODS: We performed a nested case-control analysis with 4,975 cases of acute MI and 20,000 controls, frequency matched to cases by age, sex, and calendar year. RESULTS: Overall, current use of tNSAID was not associated with an increased risk of MI (RR:1.07;95%CI: 0.95–1.21). However, we found that the relative risk (RR) of MI for durations of tNSAID treatment of >1 year was 1.21 (95% CI, 1.00–1.48). The corresponding RR was 1.34 (95% CI, 1.06–1.70) for non-fatal MI. The effect was independent from dose. The small risk associated with long-term use of tNSAIDs was observed among patients not taking low-dose aspirin (RR: 1.29; 95% CI, 1.01–1.65). The effect of long-term use for individual tNSAIDs ranged from a RR of 0.87 (95% CI, 0.47–1.62) with naproxen to 1.38 (95% CI, 1.00–1.90) with diclofenac. CONCLUSION: This study adds support to the hypothesis that chronic treatment with some tNSAIDs is associated with a small increased risk of non-fatal MI. Our data are consistent with a substantial variability in cardiovascular risks between individual tNSAIDs
Short-Lived Trace Gases in the Surface Ocean and the Atmosphere
The two-way exchange of trace gases between the ocean and the atmosphere is important for both the chemistry and physics of the atmosphere and the biogeochemistry of the oceans, including the global cycling of elements. Here we review these exchanges and their importance for a range of gases whose lifetimes are generally short compared to the main greenhouse gases and which are, in most cases, more reactive than them. Gases considered include sulphur and related compounds, organohalogens, non-methane hydrocarbons, ozone, ammonia and related compounds, hydrogen and carbon monoxide. Finally, we stress the interactivity of the system, the importance of process understanding for modeling, the need for more extensive field measurements and their better seasonal coverage, the importance of inter-calibration exercises and finally the need to show the importance of air-sea exchanges for global cycling and how the field fits into the broader context of Earth System Science
A New Academic Quality at Work Tool (AQ@workT) to Assess the Quality of Life at Work in the Italian Academic Context
The present study provides evidence for a valid and reliable tool, the Academic Quality at Work Tool (AQ@workT), to investigate the quality of life at work in academics within the Italian university sector. The AQ@workT was developed by the QoL@Work research team, namely a group of expert academics in the field of work and organizational psychology affiliated with the Italian Association of Psychologists. The tool is grounded in the job demands-resources model and its psychometric properties were assessed in three studies comprising a wide sample of lecturers, researchers, and professors: a pilot study (N = 120), a calibration study (N = 1084), and a validation study (N = 1481). Reliability and content, construct, and nomological validity were supported, as well as measurement invariance across work role (researchers, associate professors, and full professors) and gender. Evidence from the present study shows that the AQ@workT represents a useful and reliable tool to assist university management to enhance quality of life, to manage work-related stress, and to mitigate the potential for harm to academics, particularly during a pandemic. Future studies, such as longitudinal tests of the AQ@workT, should test predictive validity among the variables in the tool
Salmonella enterica ssp. arizonae infection in a 43-year-old Italian man with hypoglobulinemia: a case report and review of the literature
<p>Abstract</p> <p>Introduction</p> <p><it>Salmonella enterica </it>ssp. <it>arizonae </it>is an uncommon human pathogen with serious infections reported in immunocompromised hosts. In Europe, only a few cases have been described. Patients with this infection usually have a history of contact with reptiles or travel abroad. We present a case report of infection in a patient with hypoglobulinemia and a literature review.</p> <p>Case presentation</p> <p>We describe the case of a 43-year-old Caucasian Italian man with hypoglobulinemia who presented to our hospital with sepsis and diarrhea. A stool culture yielded <it>S. enterica </it>ssp. <it>arizonae</it>. Our patient was treated with oral ciprofloxacin and made a full recovery. We also present a review of the cases of <it>S. enterica </it>ssp. <it>arizonae </it>infections previously reported in Europe.</p> <p>Conclusions</p> <p>The majority of infections from <it>S. enterica </it>ssp. <it>arizonae </it>occur in patients who are immunocompromised. Data from the literature suggests that it may be difficult to eradicate the bacteria and thus, prolonged antibiotic courses are often used. It would be advisable for clinicians to investigate for pre-existing immune dysfunction if <it>S. enterica </it>ssp. <it>arizonae </it>is isolated. In Italy, although there have only been a few cases, the likely route of transmission remains unclear and requires further surveillance.</p
Reporting conditionals with modals
Conditionals and modals work in tandem in some instances of practical reasoning, or decision making. Consider the following example (from Kratzer 2012):
a. I want to become a mayor.
b. (q) I will become a mayor only if (p) I go to the pub.
c. Therefore, I should go to the pub.
Given what the cogniser wants (a) and the relevant circumstances (b), the conclusion that the cogniser goes to the pub comes out as necessary. Hence, the presence of the necessity modal should in (c). Indeed, given the context of (a), the necessity modal in (c) is simply a reflection of the necessity of p for q, which is overtly represented by the use of the ‘only if p, q’ construction. This chapter looks into whether indirect reports of conditionals – in particular, indirect reports which involve the use of a modal verb – are sensitive to the necessity of p for q in cases where necessity is not overtly represented in a conditional, as in ‘if p, q’ formulations.
We report on two online experiments into the relation between (i) perceived necessity or sufficiency of the truth of a conditional antecedent for the truth of the consequent, and (ii) the formulation of an indirect report of a conditional with necessity or possibility modals (have to, should, could). In Experiment 1, the ‘necessity/sufficiency of p for q’ variable was manipulated by contextually altering the number of alternative antecedents (e.g. Cummins et al. 1991; Thompson 1994; Politzer 2003). It was found that modals used in indirect reports of ‘if p, q’ conditionals co-vary with the number of alternative antecedents in predictable ways. This suggests that modals used in indirect reports of ‘if p, q’ conditionals may be a diagnostic for biconditional versus material interpretations of conditionals. The aim of Experiment 2 was to find out whether the results of Experiment 1 could be replicated in contexts which lower/eliminate the believability of the conditionals. It was found that manipulating the believability variable has no reliable effect on the results
Reporting conditionals with modals
Conditionals and modals work in tandem in some instances of practical reasoning, or decision making. Consider the following example (from Kratzer 2012):
a. I want to become a mayor.
b. (q) I will become a mayor only if (p) I go to the pub.
c. Therefore, I should go to the pub.
Given what the cogniser wants (a) and the relevant circumstances (b), the conclusion that the cogniser goes to the pub comes out as necessary. Hence, the presence of the necessity modal should in (c). Indeed, given the context of (a), the necessity modal in (c) is simply a reflection of the necessity of p for q, which is overtly represented by the use of the ‘only if p, q’ construction. This chapter looks into whether indirect reports of conditionals – in particular, indirect reports which involve the use of a modal verb – are sensitive to the necessity of p for q in cases where necessity is not overtly represented in a conditional, as in ‘if p, q’ formulations.
We report on two online experiments into the relation between (i) perceived necessity or sufficiency of the truth of a conditional antecedent for the truth of the consequent, and (ii) the formulation of an indirect report of a conditional with necessity or possibility modals (have to, should, could). In Experiment 1, the ‘necessity/sufficiency of p for q’ variable was manipulated by contextually altering the number of alternative antecedents (e.g. Cummins et al. 1991; Thompson 1994; Politzer 2003). It was found that modals used in indirect reports of ‘if p, q’ conditionals co-vary with the number of alternative antecedents in predictable ways. This suggests that modals used in indirect reports of ‘if p, q’ conditionals may be a diagnostic for biconditional versus material interpretations of conditionals. The aim of Experiment 2 was to find out whether the results of Experiment 1 could be replicated in contexts which lower/eliminate the believability of the conditionals. It was found that manipulating the believability variable has no reliable effect on the results
Structural and Functional Similarities between Osmotin from Nicotiana Tabacum Seeds and Human Adiponectin
Osmotin, a plant protein, specifically binds a seven transmembrane domain receptor-like protein to exert its biological activity via a RAS2/cAMP signaling pathway. The receptor protein is encoded in the gene ORE20/PHO36 and the mammalian homolog of PHO36 is a receptor for the human hormone adiponectin (ADIPOR1). Moreover it is known that the osmotin domain I can be overlapped to the β-barrel domain of adiponectin. Therefore, these observations and some already existing structural and biological data open a window on a possible use of the osmotin or of its derivative as adiponectin agonist. We have modelled the three-dimensional structure of the adiponectin trimer (ADIPOQ), and two ADIPOR1 and PHO36 receptors. Moreover, we have also modelled the following complexes: ADIPOQ/ADIPOR1, osmotin/PHO36 and osmotin/ADIPOR1. We have then shown the structural determinants of these interactions and their physico-chemical features and analyzed the related interaction residues involved in the formation of the complexes. The stability of the modelled structures and their complexes was always evaluated and controlled by molecular dynamics. On the basis of these results a 9 residues osmotin peptide was selected and its interaction with ADIPOR1 and PHO36 was modelled and analysed in term of energetic stability by molecular dynamics. To confirm in vivo the molecular modelling data, osmotin has been purified from nicotiana tabacum seeds and its nine residues peptide synthesized. We have used cultured human synovial fibroblasts that respond to adiponectin by increasing the expression of IL-6, TNF-alpha and IL-1beta via ADIPOR1. The biological effect on fibroblasts of osmotin and its peptide derivative has been found similar to that of adiponectin confirming the results found in silico
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