2,258 research outputs found
Switchable Ï-electronic network of bis(α-oligothienyl)-substituted hexaphyrins between helical versus rectangular circuit
The switching phenomena of conformation with Ï-electronic network through deprotonation-protonation processes were investigated by employing a series of 5, 20-bis(α-oligothienyl) substituted hexaphyrins(1.1.1.1.1.1). They showed significant changes in the absorption and emission spectra with deprotonation, and returned to the initial state with protonation. Through NMR measurements and single crystal X-ray diffraction analysis, we found that the 5, 20-bis(α-oligothienyl) substituted hexaphyrins, which possess acyclic, helical electronic networks involving oligothienyl chains in dumbbell conformations (type-I) in a neutral form, underwent effective deprotonation upon treatment with tetrabutylammonium fluoride (TBAF) to generate the corresponding dianions, which display cyclic electronic networks with enhanced aromaticity in rectangular conformations (type-II). Our quantum calculation results provide an unambiguous description for the switchable conformation and Ï-conjugation, which revealed that a deprotonation-induced enhanced aromatic conjugation pathway is involved in the switchable Ï-electronic network
Economic Evaluations of Gestational Diabetes Mellitus Screening: A Systematic Review
BACKGROUND: This study aims to find evidence of the cost-effectiveness of gestational diabetes mellitus (GDM) screening and assess the quality of current economic evaluations which have shown different conclusions with a variation in screening methods, data sources, outcome indicators, and implementation in diverse organizational contexts. SEARCH STRATEGY: Embase, Medline, Web of Science, HTA, and NHSEED databases were searched till June 2019. SELECTION CRITERIA: Studies on economic evaluation reporting both cost and health outcomes of GDM screening programs in English language. DATA COLLECTION AND ANALYSIS: The quality of the studies was assessed using Drummond's checklist. The general characteristics, main assumptions, and results of the economic evaluations were summarized. MAIN RESULTS: Our search yielded ten eligible economic evaluations with different screening strategies comparison in different settings and perspectives. The selected papers scored 81% (68%-97%) on the items in Drummond's checklist on average. In general, a screening program is cost-effective (C-E) or even dominant over no screening. The 1-step screening, with more cases detected, is more likely to be C-E than the 2-step screening. Universal screening is more likely to be C-E than screening targeting the high-risk population. Parameters affecting cost-effectiveness include: diagnosis criteria, epidemiological characteristics of the population, efficacy of screening and treatment, and costs. CONCLUSIONS: Most studies found GDM screening to be cost-effective, though uncertainties remain due to many factors. The quality assessment identified weaknesses in the economic evaluations in terms of integrating existing data, measuring costs and consequences, analyzing perspectives, and adjusting for uncertainties
Finding iteration patterns in dynamic Web page authoring
The final publication is available at Springer via http://dx.doi.org/10.1007/11431879_10Revised Selected Papers of the Joint Working Conferences EHCI-DSVIS 2004, Hamburg, Germany, July 11-13, 2004Most of the current WWW is made up of dynamic pages. The development of dynamic pages is a difficult and costly endeavour, out-of-reach for most users, experts, and content producers. We have developed a set of techniques to support the edition of dynamic web pages in a WYSIWYG environment. In this paper we focus on specific techniques for inferring changes to page generation procedures from users actions on examples of the pages generated by these procedures. More specifically, we propose techniques for detecting iteration patterns in usersâ behavior in web page editing tasks involving page structures like lists, tables and other iterative HTML constructs. Such patterns are used in our authoring tool, DESK, where a specialized assistant, DESK-A, detects iteration patterns and generates, using Programming by Example, a programmatic representation of the userâs actions. Iteration patterns help obtain a more detailed characterization of usersâ intent, based on user monitoring techniques, that is put in relation to application knowledge automatically extracted by our system from HTML pages. DESK-A relieves end-users from having to learn programming and specification languages for editing dynamic-generated web pages.The work reported in this paper is being supported by the Spanish Ministry of Science
and Technology (MCyT), project number TIC2002-194
Tau Physics: Theory Overview
The present status of some selected topics on tau physics is presented:
charged-current universality tests, bounds on lepton-flavour violation, the
determination of alpha_s from the inclusive tau hadronic width, the measurement
of |V_{us}| through the Cabibbo-suppressed decays of the tau, and the
theoretical description of the "tau -> nu_tau K pi" spectrum.Comment: Invited talk at the 2008 International Workshop on e+e- collisions
from Phi to Psi (PhiPsi08, Frascati, Italy, 7-10 April 2008
The effects of ram-pressure stripping on the internal kinematics of simulated spiral galaxies
We investigate the influence of ram-pressure stripping on the internal gas
kinematics of simulated spiral galaxies. Additional emphasis is put on the
question of how the resulting distortions of the gaseous disc are visible in
the rotation curve and/or the full 2D velocity field of galaxies at different
redshifts. A Milky-Way type disc galaxy is modelled in combined
N-body/hydrodynamic simulations with prescriptions for cooling, star formation,
stellar feedback, and galactic winds. This model galaxy moves through a
constant density and temperature gas, which has parameters similar to the
intra-cluster medium (ICM). Rotation curves (RCs) and 2D velocity fields of the
gas are extracted from these simulations in a way that follows the procedure
applied to observations of distant, small, and faint galaxies as closely as
possible. We find that the appearance of distortions of the gaseous disc due to
ram-pressure stripping depends on the direction of the acting ram pressure. In
the case of face-on ram pressure, the distortions mainly appear in the outer
parts of the galaxy in a very symmetric way. In contrast, in the case of
edge-on ram pressure we find stronger distortions. The 2D velocity field also
shows signatures of the interaction in the inner part of the disc. At angles
smaller than 45 degrees between the ICM wind direction and the disc, the
velocity field asymmetry increases significantly compared to larger angles.
Compared to distortions caused by tidal interactions, the effects of
ram-pressure stripping on the velocity field are relatively low in all cases
and difficult to observe at intermediate redshift in seeing-limited
observations. (abridged)Comment: 9 pages, 11 figures, accepted for publication in A&
On the influence of ram-pressure stripping on the star formation of simulated spiral galaxies
We investigate the influence of ram-pressure stripping on the star formation
and the mass distribution in simulated spiral galaxies. Special emphasis is put
on the question where the newly formed stars are located. The stripping radius
from the simulation is compared to analytical estimates. Disc galaxies are
modelled in combined N-body/hydrodynamic simulations (GADGET-2) with
prescriptions for cooling, star formation, stellar feedback, and galactic
winds. These model galaxies move through a constant density and temperature
gas, which has parameters comparable to the intra-cluster medium (ICM) in the
outskirts of a galaxy cluster (T=3 keV ~3.6x10^7 K and rho=10^-28 g/cm^3). With
this numerical setup we analyse the influence of ram-pressure stripping on the
star formation rate of the model galaxy. We find that the star formation rate
is significantly enhanced by the ram-pressure effect (up to a factor of 3).
Stars form in the compressed central region of the galaxy as well as in the
stripped gas behind the galaxy. Newly formed stars can be found up to hundred
kpc behind the disc, forming structures with sizes of roughly 1 kpc in diameter
and with masses of up to 10^7 M_sun. As they do not possess a dark matter halo
due to their formation history, we name them 'stripped baryonic dwarf'
galaxies. We also find that the analytical estimate for the stripping radius
from a Gunn & Gott (1972) criterion is in good agreement with the numerical
value from the simulation. Like in former investigations, edge-on systems lose
less gas than face-on systems and the resulting spatial distribution of the gas
and the newly formed stars is different.Comment: 8 pages, 7 figures, accepted for publication in A&
Coronary heart disease and stroke disease burden attributable to fruit and vegetable intake in Japan: projected DALYS to 2060.
BACKGROUND: Fruit and vegetable consumption was considered a protective effect against cardiovascular and cerebrovascular diseases (CVDs). This study aimed to project the reduction in the CVD burden under different scenarios of increased fruit and vegetable intake in Japan by 2060. METHODS: Population attributable fractions (PAF) were calculated by gender and age in 2015. The projection considered five scenarios for 2015, 2030, 2045, and 2060: 1) a baseline of no changes in intake; 2) a moderate increase in fruit intake (extra 50âg/day or 1/2 serving); 3) an high increase in fruit intake (extra 100âg/day or 1 serving); 4) a moderate increase in vegetable intake (extra 70âg/day or 1 serving); and 5) an high increase in vegetable intake (extra 140âg/day or 2 servings). Potentially preventable disability-adjusted life years (DALYs) for CVDs were estimated for each scenario. Monte Carlo simulations were performed to calculate the 95% confidence intervals of the estimates. RESULTS: Across all age groups, men had a higher daily vegetable intake than women (292.7âg/dâ>â279.3âg/d) but a lower daily fruit intake (99.3âg/dâ<â121.0âg/d). Comparing with recommended intake level (350âg/d of vegetable and 200âg/d of fruit), the total CVD burden was estimated to be 302,055 DALYs attributable to inadequate fruit consumption in 2015, which accounted for 12.6% of the total CVD burden (vegetable: 202,651 DALYs; 8.5%). In 2060, the percentage of the CVD burden due to insufficient intake of fruit is estimated to decrease to 7.9% under the moderate increase scenario and to decrease to 4.5% under the high increase scenario (vegetable: 5.4%; 2.4%). CONCLUSIONS: The study suggested that a relevantly large percentage of the CVD burden can be alleviated by promoting even modest increases in fruit and vegetable consumption in Japan
Removal and mixing of the coronal gas from satellites in galaxy groups: cooling the intragoup gas
The existence of an extended hot gaseous corona surrounding clusters, groups
and massive galaxies is well established by observational evidence and
predicted by current theories of galaxy formation. When a small galaxy collides
with a larger one, their coronae are the first to interact, producing
disturbances that remove gas from the smaller system and settle it into the
corona of the larger one. For a Milky-Way-size galaxy merging into a low-mass
group, ram pressure stripping and the Kelvin-Helmholtz instability are the most
relevant of these disturbances. We argue that the turbulence generated by the
latter mixes the material of both coronae in the wake of the orbiting satellite
creating a "warm phase" mixture with a cooling time a factor of several shorter
than that of the ambient intragroup gas. We reach this conclusion using
analytic estimates, as well as adiabatic and dissipative high resolution
numerical simulations of a spherical corona subject to the ablation process of
a constant velocity wind with uniform density and temperature. Although this is
a preliminary analysis, our results are promising and we speculate that the
mixture could potentially trigger in situ star formation and/or be accreted
into the central galaxy as a cold gas flow resulting in a new mode of star
formation in galaxy groups and clusters.Comment: 15 pages, 5 figures, accepted for publication in MNRA
The interaction of dark matter cusp with the baryon component in disk galaxies
In this paper we examine the effect of the formation and evolution of the
disk galaxy on the distribution of dark halo matter. We have made simulations
of isolated dark matter (DM) halo and two component (DM + baryons). N-body
technique was used for stellar and DM particles and TVD MUSCL scheme for
gas-dynamic simulations. The simulations include the processes of star
formation, stellar feedback, heating and cooling of the interstellar medium.
The results of numerical experiments with high spatial resolution let us to
conclude in two main findings. First, accounting of star formation and
supernova feedback resolves the so-called problem of cusp in distribution of
dark matter predicted by cosmological simulations. Second, the interaction of
dark matter with dynamic substructures of stellar and gaseous galactic disk
(e.g., spiral waves, bar) has an impact on the shape of the dark halo. In
particular, the in-plane distribution of dark matter is more symmetric in runs,
where the baryonic component was taken into account.Comment: 7 pages, 6 figure
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