1,019 research outputs found
Theoretical study of charge exchange dynamics in He + NO collisions
We investigate the charge transfer mechanism in the collisions of helium ions
on nitric oxide using a molecular description framework with consideration of
the orientation of the projectile toward the target. The anisotropy of the
collision process has been analysed in detail in connection with the
non-adiabatic interactions around avoided crossings. Potential energy curves,
radial and rotational coupling matrix elements have been determined by means of
ab initio quantum chemical methods. The collision dynamics is performed in the
[1.-25.] keV collision energy range using a semiclassical approach, and the
total electron transfer cross sections are analysed with regard to available
experimental data.Comment: 16 pages, 3 tables, 6 figure
Exploring Set-Theoretic Practices of Youth Engagement in Connective Journalism: What We Lose in School-Mathematical Descriptions
Analyzing youth video submissions regarding COVID-19 to KQEDâs âLetâs Talk About the Electionâ website, we explore the mathematics these youth engaged in through their submissions without creating any explicit connection to school mathematical concepts or standards. Our focus is the studentsâ construction of sets (e.g. sets of nurses, doctors, American workers), as a means of creating connection with voters and other media authors through Marchi and Clarkâs (2021) construct of connective journalism. We observe these youth constructing sets of varying sizes and reflecting on how these sets are contextualized within a larger political dialogue. We also attempt to rewrite part of one student composition using school mathematical symbolic logic, reviewing what in the studentâs message is no longer present in the school mathematical analogue and why. We conclude by encouraging practitioners to explore with their students other instances in which they can challenge numerical or school mathematical symbolic writing as a superior means of communicating ideas
Greenhouse gas emissions in the agricultural phase of wine production in the Maremma rural district (Tuscany, Italy).
In recent years, there has been an increasing interest from retailers, industries and environmental associations in estimating the life cycle of greenhouse gases emitted in the atmosphere from everyday products and services, also known as carbon footprint (CF). Life cycle assessment (LCA) is the most common methodology used to evaluate the environmental impact of a product. This approach was largely used in many industrial sectors and was also recently applied to quantify the environmental impact of the agri-food chain. Within agri-food products, wine is one of the most analysed, both for its importance in economic production and in the world distribution market. The present study is a part of the Carbon Label Project carried out in the wine production chain in the Maremma rural district (Tuscany, Italy). The project assessed the greenhouse
gas (GHG) emissions from wine production for labelling purposes.
Here, we evaluated the environmental performances of four high
quality wines for carbon labelling. The international standards ISO
14040, ISO 14044, and the Product Category Rules (PCR) Wine from Fresh Grapes (except sparkling wine) and Grape Must for the Environmental Product Declaration (EPD) certification, specifically for
Climate Declaration, were used in order to carry out our analyses. The functional unit (FU) used here was one 0.75 L bottle of wine. The system boundaries were set from the vineyard planting to the distribution and waste disposal. The global warming potential (GWP) of four investigated wines was found to lie between 0.6 and 1.3 kg CO2-eq./bottle, showing a value comparable with literature. With all the four wines analysed, the agricultural phase covered, on average, 22% of the total GWP/bottle, while the main impact was in the production of the glass bottle. The results showed that the vineyard-planting phase has a significant impact on the wine CF, thus it has to be considered in the life cycle, while in literature it is frequently omitted. On the contrary, the pre-production phase did not present a relevant impact. The use of nitrogen fertilisers, the grapesâ yield and N2O emissions were the parameters that mostly affected the carbon footprint in the agricultural phase, as underlined by the sensitivity analysis
Is quarantine for covid-19 pandemic associated with psychological burden in primary ciliary dyskinesia?
Background: Information on psychological impact of COVID-19 quarantine in primary ciliary dyskinesia (PCD), a chronic disorder with recurrent pulmonary exacerbations, is lacking. Psychological well-being was prospectively assessed during COVID-19 lockdown in Italy in a PCD population. Methods: we recruited 27 PCD patients and 27 healthy controls. To assess psychological well-being, psychological general well-being index and parenting stress index-short questionnaires were administered to participants â„15 years-old and to mothers of participants <15 years-old, respectively. The PCD exacerbations since outbreak onset and frequency of quarantine weekly chest physiotherapy were compared to the same period of 2019. Outcomes: 70% of PCD mothers and 90% of PCD patients did not show parental stress levels or distress levels, respectively, and these groups showed no significant difference in stress compared to controls. The PCD pulmonary exacerbations occurred less frequently and weekly chest physiotherapy sessions significantly increased compared to the same period during 2019 (p < 0.05). Interpretation: During COVID-19 quarantine, a PCD population showed psychological well-being. Low exacerbation rate, explained by lower infectious exposure or improved compliance to chest physiotherapy, likely contributed to psychological well-being. Evaluating psychological burden and parental stress is a valuable tool for measuring the emotional impact of PCD and improving PCD medical care
Dielectric formalism and damping of collective modes in trapped Bose-Einstein condensed gases
We present the general dielectric formalism for Bose-Einstein condensed
systems in external potential at finite temperatures. On the basis of a model
arising within this framework as a first approximation in an intermediate
temperature region for large condensate we calculate the damping of low-energy
excitations in the collisionless regime.Comment: 4 pages, no figures, RevTe
Anti-TNF-alpha agents and endothelial function in rheumatoid arthritis: A systematic review and meta-analysis
Rheumatoid arthritis (RA) has been associated with endothelial dysfunction, a pathophysiological feature of atherosclerosis. Our aim was to determine whether TNF-\u3b1 blockade has a beneficial effect on endothelial function in RA. We performed a systematic review with meta-analysis to evaluate the effect of anti-TNF-\u3b1 agents on endothelial function in RA patients. MedLine, Cochrane CENTRAL and SCOPUS were searched up to March 2016. Inclusion criteria were: 1) randomised controlled trial (RCT), quasi-RCT, before-after cohort study; 2) including RA patients; 3) treatment with anti-TNF-\u3b1 medications; 4) evaluating the change from baseline in endothelial function. The search strategy retrieved 180 records, of which 20 studies were included in the systematic review. Pooled analysis using a random-effects model demonstrated a significant improvement in endothelial function following anti-TNF-\u3b1 treatment (SDM 0.987, 95%CI [0.64-1.33], p < 0.0001). Generalisation of the results of the meta-analysis may be limited due to the presence of heterogeneity (I2 = 82.65%, p < 0.001) and evidence of possible publication bias. Meta-regression showed that endothelial function measurement technique was a significant contributor to heterogeneity. In conclusion, although limited by the methodological quality of the included studies, our meta-analysis suggests that anti-TNF-\u3b1 treatment may improve endothelial function in RA patients
Supersymmetric Homogeneous Quantum Cosmologies Coupled to a Scalar Field
Recent work on supersymmetric Bianchi type IX cosmologies coupled to a
scalar field is extended to a general treatment of homogeneous quantum
cosmologies with explicitely solvable momentum constraints, i.e. Bianchi types
I, II, VII, VIII besides the Bianchi type IX, and special cases, namely the
Friedmann universes, the Kantowski-Sachs space, and Taub-NUT space. Besides the
earlier explicit solution of the Wheeler DeWitt equation for Bianchi type IX,
describing a virtual wormhole fluctuation, an additional explicit solution is
given and identified with the `no-boundary state'.Comment: 23 PAGE
Limitations of squeezing due to collisional decoherence in Bose-Einstein condensates
We study the limitations for entanglement due to collisional decoherence in a
Bose-Einstein condensate. Specifically we consider relative number squeezing
between photons and atoms coupled out from a homogeneous condensate. We study
the decay of excited quasiparticle modes due to collisions, in condensates of
atoms with one or two internal degrees of freedom. The time evolution of these
modes is determined in the linear response approximation to the deviation from
equilibrium. We use Heisenberg-Langevin equations to derive equations of motion
for the densities and higher correlation functions which determine the
squeezing. In this way we can show that decoherence due to quasiparticle
interactions imposes an important limit on the degree of number squeezing which
may be achieved. Our results are also relevant for the determination of
decoherence times in other experiments based on entanglement, e.g. the slowing
and stopping of light in condensed atomic gases using dark states.Comment: 16 pages RevTeX, 3 figure
Quantum Cosmology of Generalized Two--Dimensional Dilaton Gravity Models
The quantum cosmology of two-dimensional dilaton-gravity models is
investigated. A class of models is mapped onto the constrained
oscillator-ghost-oscillator model. A number of exact and approximate solutions
to the corresponding Wheeler-DeWitt equation are presented. A wider class of
minisuperspace models that can be solved in this fashion is identified.
Supersymmetric extensions to the induced gravity theory and the bosonic string
theory are then considered and closed-form solutions to the associated quantum
constraints are derived. The possibility of applying the third-quantization
procedure to two-dimensional dilaton-gravity is briefly discussed.Comment: 28 pages, late
Properties of excitations in systems with a spinor Bose-Einstein condensate
General theory in case of homogenous Bose-Einstein condensed systems with
spinor condensate is presented for the correlation functions of density and
spin fluctuations and for the one-particle propagators as well. The random
phase approximation is investigated and the damping of the modes is given in
the intermediate temperature region. It is shown that the collective and the
one-particle excitation spectra do not coincide fully.Comment: 5 pages, 1 figur
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