876 research outputs found
Quasars: What turns them off?
(Abridged) We explore the idea that the anti-hierarchical turn-off observed
in the quasar population arises from self-regulating feedback, via an outflow
mechanism. Using a detailed hydrodynamic simulation we calculate the luminosity
function of quasars down to a redshift of z=1 in a large, cosmologically
representative volume. Outflows are included explicitly by tracking halo
mergers and driving shocks into the surrounding intergalactic medium. Our
results are in excellent agreement with measurements of the spatial
distribution of quasars, and we detect an intriguing excess of galaxy-quasar
pairs at very short separations. We also reproduce the anti-hierarchical
turnoff in the quasar luminosity function, however, the magnitude of the
turn-off falls short of that observed as well as that predicted by analogous
semi-analytic models. The difference can be traced to the treatment of gas
heating within galaxies. The simulated galaxy cluster L_X-T relationship is
close to that observed for z~1 clusters, but the simulated galaxy groups at z=1
are significantly perturbed by quasar outflows, suggesting that measurements of
X-ray emission in high-redshift groups could well be a "smoking gun" for the
AGN heating hypothesis.Comment: 16 pages, 11 figures, submitted to ApJ, comments welcome
The Role of Heating and Enrichment in Galaxy Formation
We show that the winds identified with high-redshift low-mass galaxies may
strongly affect the formation of stars in more massive galaxies that form
later. With 3D realizations of a simple linear growth model we track gas
shocking, metal enrichment, and cooling, together with dark halo formation. We
show that outflows typically strip baryonic material out of collapsing
intermediate mass halos, suppressing star formation. More massive halos can
trap the heated gas but collapse late, leading to a broad bimodal redshift
distribution, with a larger characteristic mass associated with the lower
redshift peak. This scenario accounts for the observed bell-shaped luminosity
function of early type galaxies, explains the small number of Milky Way
satellite galaxies relative to Cold Dark Matter models predictions, and
provides a possible explanation for the lack of metal poor G-dwarfs in the
solar neighborhood and the more general lack of low-metallicity stars in
massive galaxies relative to ``closed-box'' models of chemical enrichment.
Intergalactic medium heating from outflows should produce spectral distortions
in the cosmic microwave background that will be measurable with the next
generation of experiments.Comment: 19 pages, 12 figures, accepted to ApJ, models refined and minor
revisions mad
Schmidt balls around the identity
Robustness measures as introduced by Vidal and Tarrach [PRA, 59, 141-155]
quantify the extent to which entangled states remain entangled under mixing.
Analogously, we introduce here the Schmidt robustness and the random Schmidt
robustness. The latter notion is closely related to the construction of Schmidt
balls around the identity. We analyse the situation for pure states and provide
non-trivial upper and lower bounds. Upper bounds to the random Schmidt-2
robustness allow us to construct a particularly simple distillability
criterion. We present two conjectures, the first one is related to the radius
of inner balls around the identity in the convex set of Schmidt number
n-states. We also conjecture a class of optimal Schmidt witnesses for pure
states.Comment: 7 pages, 1 figur
Are wearable heart rate measurements accurate to estimate aerobic energy cost during low-intensity resistance exercise?
The aim of the present study was to assess the accuracy of heart rate to estimate energy cost during eight resistance exercises performed at low intensities: half squat, 45° inclined leg press, leg extension, horizontal bench press, 45° inclined bench press, lat pull down, triceps extension and biceps curl. 56 males (27.5 ± 4.9 years, 1.78 ± 0.06 m height, 78.67 ± 10.7 kg body mass and 11.4 ± 4.1% estimated body fat) were randomly divided into four groups of 14 subjects each. Two exercises were randomly assigned to each group and subjects performed four bouts of 4-min constant-intensity at each assigned exercise: 12%, 16%, 20% and 24% 1-RM. Exercise and intensity order were random. Each subject performed no more than 2 bouts in the same testing session. A minimum recovery of 24h was kept between sessions. During testing VO2 was measured with Cosmed K4b2 and heart rate was measured with Polar V800 monitor. Energy cost was calculated from mean VO2 during the last 30-s of each bout by using the energy equivalent 1 ml O2 = 5 calorie. Linear regressions with heart rate as predictor and energy cost as dependent variable were build using mean data from all subjects. Robustness of the regression lines was given by the scatter around the regression line (Sy.x) and Bland-Altman plots confirmed the agreement between measured and estimated energy costs. Significance level was set at p≤0.05. The regressions between heart rate and energy cost in the eight exercises were significant (p<0.01) and robustness was: half squat (Sy.x = 0,48 kcal·min-1), 45° inclined leg press (Sy.x = 0,54 kcal·min-1), leg extension (Sy.x = 0,59 kcal·min-1), horizontal bench press (Sy.x = 0,47 kcal·min-1), 45° inclined bench press (Sy.x = 0,54 kcal·min-1), lat pull down (Sy.x = 0,28 kcal·min-1), triceps extension (Sy.x = 0,08 kcal·min-1) and biceps curl (Sy.x = 0,13 kcal·min-1). We conclude that during low-intensity resistance exercises it is possible to estimate aerobic energy cost by wearable heart rate monitors with errors below 10% in healthy young trained males.This research was supported by Norte Portugal Regional Operational Programme (NORTE 2020), through Portugal 2020 and the European Regional Development Fund, NanoSTIMA, NORTE-01-0145- FEDER-000016 to VMR. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.info:eu-repo/semantics/publishedVersio
Processo de delimitação da região produtora dos vinhos de altitude de Santa Catarina para indicação geográfica.
A região produtora dos vinhos de altitude de Santa Catarina abrange os produtores de vinhos finos identificados nos cadastros citados no Capítulo 1. A qualidade dos vinhos produzidos nessa região, somada a suas características físicas, socioeconômicas e culturais, justifica e subsidia a constituição de uma indicação geográfica (IG)
Experimental implementation of a NMR entanglement witness
Entanglement witnesses (EW) allow the detection of entanglement in a quantum
system, from the measurement of some few observables. They do not require the
complete determination of the quantum state, which is regarded as a main
advantage. On this paper it is experimentally analyzed an entanglement witness
recently proposed in the context of Nuclear Magnetic Resonance (NMR)
experiments to test it in some Bell-diagonal states. We also propose some
optimal entanglement witness for Bell-diagonal states. The efficiency of the
two types of EW's are compared to a measure of entanglement with tomographic
cost, the generalized robustness of entanglement. It is used a GRAPE algorithm
to produce an entangled state which is out of the detection region of the EW
for Bell-diagonal states. Upon relaxation, the results show that there is a
region in which both EW fails, whereas the generalized robustness still shows
entanglement, but with the entanglement witness proposed here with a better
performance
Investigations into in situ Enterococcus faecalis biofilm removal by passive and active sodium hypochlorite irrigation delivered into the lateral canal of a simulated root canal model
Aim To investigate in situ Enterococcus faecalis biofilm removal from the lateral canal of a simulated root canal system using passive or active irrigation protocols. Methodology Root canal models (n = 43) were manufactured from transparent resin materials using 3D-printing. Each canal was created with an 18 mm length, apical size 30, a .06 taper, and a lateral canal of 3 mm length, 0.3 mm diameter. Biofilms were grown on the lateral canal and apical 3 mm of the main canal for 10 days. Biofilm of three models was examined using SEM. The other forty models were divided to four groups (n = 10). The models were observed under a fluorescence microscope. Following 60 s of 9 mL of 2.5% NaOCl irrigation using syringe and needle, the irrigant was either left stagnant in the canal or activated using gutta-percha, sonic or ultrasonic methods for 30 s. Images were then captured every second using an external camera. The residual biofilm percentages were measured using image analysis software. The data were analyzed using generalized linear mixed models. A significance level of 0.05 was used throughout. Results The greatest level of biofilm removal was with ultrasonic agitation (66.76%) followed by sonic (45.49%), manual agitation (43.97%), and passive irrigation groups (38.67%) respectively. The differences were significant between the residual biofilm in the passive irrigation and both sonic & ultrasonic groups (P = 0.001). Conclusion Agitation resulted in better penetration of the 2.5% NaOCl into the lateral canal of an artificial root canal model. Ultrasonic agitation of NaOCl improved the removal of biofilm
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