507 research outputs found
POD-Based reduced order methods for optimal control problems governed by parametric partial differential equation with varying boundary control
In this work we propose tailored model order reduction for varying boundary optimal con-trol problems governed by parametric partial differential equations. With varying boundary control, we mean that a specific parameter changes where the boundary control acts on the system. This peculiar formulation might benefit from model order reduction. Indeed, fast and reliable simulations of this model can be of utmost usefulness in many applied fields, such as geophysics and energy engineering. However, varying boundary control features very complicated and diversified parametric behaviour for the state and adjoint variables. The state solution, for example, changing the boundary control parameter, might feature transport phenomena. Moreover, the problem loses its affine structure. It is well known that classical model order reduction techniques fail in this setting, both in accuracy and in efficiency. Thus, we propose reduced approaches inspired by the ones used when dealing with wave-like phenomena. Indeed, we compare standard proper orthogonal decomposi-tion with two tailored strategies: geometric recasting and local proper orthogonal decom-position. Geometric recasting solves the optimization system in a reference domain simpli-fying the problem at hand avoiding hyper-reduction, while local proper orthogonal decom-position builds local bases to increase the accuracy of the reduced solution in very general settings (where geometric recasting is unfeasible). We compare the various approaches on two different numerical experiments based on geometries of increasing complexity.& COPY; 2023 Elsevier Inc. All rights reserved
Not smoking is associated with lower risk of hypertension: results of the Olivetti Heart Study.
Few epidemiological investigations evaluated the role of smoking
cessation on blood pressure (BP), and the results are not univocal. Therefore,
the aim of this study was to assess the effect of smoking cessation on the risk
to develop hypertension (HPT) and on BP values.
METHODS: This longitudinal study, with a follow-up period of 8 years, included
the participants of the Olivetti Heart Study. Participants were 430 untreated
normotensive non-diabetic men with normal renal function, examined twice in
1994-95 and in 2002-04. The sample included current smokers (S, n = 212), former
smokers (ES, n = 145) and never smokers (NS, n = 73) at baseline.
RESULTS: Basal body mass index (BMI), systolic blood pressure (SBP) and diastolic
blood pressure (DBP) were significantly higher in ES than in S (ES vs. S; BMI:
27.0 ± 2.5 vs. 26.1 ± 2.9 kg/m(2); P < 0.01; SBP/DBP: 121.2 ± 9.3/80.0 ± 5.8 vs.
19.1 ± 9.9/77.4 ± 6.7 mm Hg; P < 0.05; M ± SD). After 8 years of follow-up, BP
changes (Î) were significantly lower in ES than in S (ÎSBP/DBP: 12.6 ± 13.4/7.9 ±
8.1 vs. 16.0 ± 14.9/10.3 ± 10.1 mm Hg; P < 0.05; M ± SD), also after adjustment
for potential confounders. Moreover, at the last examination, the overall HPT
prevalence was 33%, with lower values in ES than in S (25 vs. 38%, P = 0.01).
After accounting for age, BP and BMI at baseline, and changes in smoking habit
over the 8-year period, ES still had significant lower risk of HPT than S (odds
ratio 0.30, 95% confidence interval 0.15-0.58; P < 0.01).
CONCLUSIONS: In this sample of healthy men, smoking cessation was associated with
lower BP increment and minor HPT risk, independently of potential confounders
A weighted POD-reduction approach for parametrized PDE-constrained Optimal Control Problems with random inputs and applications to environmental sciences
HindIII(+/â) Polymorphism of the Y Chromosome, Blood Pressure, and Serum Lipids: No Evidence of Association in Three White Populations
n/
Controlled study of the effect of angiotensin converting enzyme inhibition versus calcium-entry blockade on insulin sensitivity in overweight hypertensive patients: Trandolapril Italian Study (TRIS).
Suppressed CO emission and high G/D ratios in z=2 galaxies with sub-solar gas-phase metallicity
We study a population of significantly sub-solar enrichment galaxies at z=1.99, to investigate how molecular gas, dust and star-formation relate in low-metallicity galaxies at the peak epoch of star-formation. We target our sample with several deep ALMA and VLA datasets, and find no individual detections of CO[4-3], CO[1-0] or dust, in stark contrast to the >60% detection rate expected for solar-enrichment galaxies with these MS Halpha SFRs. We find that both low and high density molecular gas (traced by CO[1-0] and CO[4-3] respectively) are affected by the low enrichment, showing sample average (stacked) luminosity deficits >0.5-0.7 dex below expectations. This is particularly pertinent for the use of high-J CO emission as a proxy of instantaneous star-formation rate. Our individual galaxy data and stacked constraints point to a strong inverse dependence âZÎł of gas-to-dust ratios (G/D) and CO-to-H2 conversion factors (aco) on metallicity at zâŒ2, with ÎłG/D<-2.2 and γαCO<-0.8, respectively. We quantify the importance of comparing G/D and aco vs. metallicity trends from the literature on a common, suitably normalised metallicity scale. When accounting for systematic offsets between different metallicity scales, our zâŒ2 constraints on these scaling relations are consistent with the corresponding relations for local galaxies. However, among those local relations, we favour those with a steep/double power-law dependence of G/D on metallicity. Finally, we discuss the implications of these findings for (a) gas mass measurements for sub-Mâ galaxies, and (b) efforts to identify the characteristic galaxy mass scale contributing most to the comoving molecular gas density at z=2
Passive galaxies as tracers of cluster environments at z~2
Even 10 billion years ago, the cores of the first galaxy clusters are often
found to host a characteristic population of massive galaxies with already
suppressed star formation. Here we search for distant cluster candidates at z~2
using massive passive galaxies as tracers. With a sample of ~40
spectroscopically confirmed passive galaxies at 1.3<z<2.1, we tune photometric
redshifts of several thousands passive sources in the full 2 sq.deg. COSMOS
field. This allows us to map their density in redshift slices, probing the
large scale structure in the COSMOS field as traced by passive sources. We
report here on the three strongest passive galaxy overdensities that we
identify in the redshift range 1.5<z<2.5. While the actual nature of these
concentrations is still to be confirmed, we discuss their identification
procedure, and the arguments supporting them as candidate galaxy clusters
(likely mid-10^13 M_sun range). Although this search approach is likely biased
towards more evolved structures, it has the potential to select still rare,
cluster-like environments close to their epoch of first appearance, enabling
new investigations of the evolution of galaxies in the context of structure
growth.Comment: 5 pages, 5 figures; A&A Letters, in pres
Satellite content and quenching of star formation in galaxy groups at z ~ 1.8
We study the properties of satellites in the environment of massive star-forming galaxies at z ~ 1.8 in the COSMOS field, using a sample of 215 galaxies on the main sequence of star formation with an average mass of ~1011Mâ. At z> 1.5, these galaxies typically trace halos of mass âł1013Mâ. We use optical-near-infrared photometry to estimate stellar masses and star formation rates (SFR) of centrals and satellites down to ~ 6 Ă 109Mâ. We stack data around 215 central galaxies to statistically detect their satellite halos, finding an average of ~3 galaxies in excess of the background density. We fit the radial profiles of satellites with simple ÎČ-models, and compare their integrated properties to model predictions. We find that the total stellar mass of satellites amounts to ~68% of the central galaxy, while spectral energy distribution modeling and far-infrared photometry consistently show their total SFR to be 25-35% of the central's rate. We also see significant variation in the specific SFR of satellites within the halo with, in particular, a sharp decrease at <100 kpc. After considering different potential explanations, we conclude that this is likely an environmental signature of the hot inner halo. This effect can be explained in the first order by a simple free-fall scenario, suggesting that these low-mass environments can shut down star formation in satellites on relatively short timescales of ~0.3 Gyr
- âŠ