1,897 research outputs found
Future constraints on neutrino isocurvature perturbations in the curvaton scenario
In the curvaton scenario, residual isocurvature perturbations can be
imprinted in the cosmic neutrino component after the decay of the curvaton
field, implying in turn a non-zero chemical potential in the neutrino
distribution. We study the constraints that future experiments like Planck,
SPIDER or CMBPol will be able to put on the amplitude of isocurvature
perturbations in the neutrino component. We express our results in terms of the
square root \gamma of the non-adiabaticity parameter \alpha and of the extra
relativistic degrees of freedom \Delta N_eff. Assuming a fiducial model with
purely adiabatic fluctuations, we find that Planck (SPIDER) will be able to put
the following upper limits at the 1sigma level: \gamma < 5.3x10^-3 (1.2x10^-2)
and \Delta N_eff < 0.16 (0.40) . CMBPol will further improve these constraints
to \gamma < 1.5x10^-3 and \Delta N_eff < 0.043. Finally, we recast these bounds
in terms of the background neutrino degeneracy parameter \xi\ and the
corresponding perturbation amplitude \sigma_\xi, and compare with the bounds on
\xi\ that can be derived from Big Bang Nucleosynthesis.Comment: 6 pages, 2 figures. References added. Matches version accepted for
publication in Phys. Rev.
Ambiguous Tests of General Relativity on Cosmological Scales
There are a number of approaches to testing General Relativity (GR) on linear
scales using parameterized frameworks for modifying cosmological perturbation
theory. It is sometimes assumed that the details of any given parameterization
are unimportant if one uses it as a diagnostic for deviations from GR. In this
brief report we argue that this is not necessarily so. First we show that
adopting alternative combinations of modifications to the field equations
significantly changes the constraints that one obtains. In addition, we show
that using a parameterization with insufficient freedom significantly tightens
the apparent theoretical constraints. Fundamentally we argue that it is almost
never appropriate to consider modifications to the perturbed Einstein equations
as being constraints on the effective gravitational constant, for example, in
the same sense that solar system constraints are. The only consistent
modifications are either those that grant near-total freedom, as in
decomposition methods, or ones which map directly to a particular part of
theory space
Mutant p53 improves cancer cells\u2019 resistance to endoplasmic reticulum stress by sustaining activation of the UPR regulator ATF6
Missense mutations in the TP53 gene are frequent in human cancers, giving rise to mutant p53 proteins that can acquire oncogenic properties. Gain of function mutant p53 proteins can enhance tumour aggressiveness by promoting cell invasion, metastasis and chemoresistance. Accumulating evidences indicate that mutant p53 proteins can also modulate cell homeostatic processes, suggesting that missense p53 mutation may increase resistance of tumour cells to intrinsic and extrinsic cancer-related stress conditions, thus offering a selective advantage. Here we provide evidence that mutant p53 proteins can modulate the Unfolded Protein Response (UPR) to increase cell survival upon Endoplasmic Reticulum (ER) stress, a condition to which cancer cells are exposed during tumour formation and progression, as well as during therapy. Mechanistically, this action of mutant p53 is due to enhanced activation of the pro-survival UPR effector ATF6, coordinated with inhibition of the pro-apoptotic UPR effectors JNK and CHOP. In a triple-negative breast cancer cell model with missense TP53 mutation, we found that ATF6 activity is necessary for viability and invasion phenotypes. Together, these findings suggest that ATF6 inhibitors might be combined with mutant p53-targeting drugs to specifically sensitise cancer cells to endogenous or chemotherapy-induced ER stress
Prospective Assessment of Sex-Related Differences in Symptom Status and Health Perception Among Patients With Atrial Fibrillation.
We prospectively assessed sex-specific differences in health perception, overall symptom status, and specific symptoms in a large cohort of patients with atrial fibrillation.
We performed a prospective multicenter observational cohort study of 1553 patients with atrial fibrillation. Patients completed questionnaires about personal characteristics, comorbidities, and symptoms on a yearly basis. Mean age was 70±11 years among women and 67±12 years among men. Health perception on a visual analogue scale ranging from 0 to 100 (with higher scores indicating better health perception) was significantly lower in women than in men (70 [interquartile range: 50-80] versus 75 [interquartile range: 60-85]; javax.xml.bind.JAXBElement@29592a5d <0.0001). More women than men had any symptoms (85.0% versus 68.3%; javax.xml.bind.JAXBElement@7ac0b4e4 <0.0001), palpitations (65.2% versus 44.4%; javax.xml.bind.JAXBElement@41229466 <0.0001), dizziness (25.6% versus 13.5%; javax.xml.bind.JAXBElement@61871784 <0.0001), dyspnea (35.7% versus 21.8%; javax.xml.bind.JAXBElement@16cc22b <0.0001), and fatigue (25.3% versus 19.1%; javax.xml.bind.JAXBElement@7ef43176 =0.006). At 1-year follow-up, symptoms decreased in both sexes but remained more frequent in women (49.1% versus 32.6%, javax.xml.bind.JAXBElement@2b200b6a <0.0001). In multivariable adjusted longitudinal regression models, female sex remained an independent predictor for lower health perception (Ă=-4.8; 95% CI, -6.5 to -3.1; javax.xml.bind.JAXBElement@72c212bd <0.0001), any symptoms (odds ratio [OR]: 2.6; 95% CI, 2.1-3.4; javax.xml.bind.JAXBElement@15d8fb54 <0.0001), palpitations (OR: 2.6; 95% CI, 2.1-3.2; javax.xml.bind.JAXBElement@4af80718 <0.0001), dizziness (OR: 2.9; 95% CI, 2.1-3.9; javax.xml.bind.JAXBElement@61282e76 <0.0001), dyspnea (OR: 2.1; 95% CI, 1.6-2.8; javax.xml.bind.JAXBElement@31d9f14 <0.0001), fatigue (OR: 1.6; 95% CI, 1.2-2.2; javax.xml.bind.JAXBElement@51cdd678 =0.0008), and chest pain (OR: 1.8; 95% CI, 1.3-2.6; javax.xml.bind.JAXBElement@5b87db9e =0.001).
Women with atrial fibrillation have a substantially higher symptom burden and lower health perception than men. These relationships persisted after multivariable adjustment and during prospective follow-up
Late-transition versus smooth H(z)-deformation models for the resolution of the Hubble crisis
Gravitational transitions at low redshifts (zt < 0.1) have been recently proposed as a solution to
the Hubble and growth tensions. Such transitions would naturally lead to a transition in the absolute
magnitude M of type Ia supernovae (SnIa) at zt (Late M Transitions - LMT) and possibly in the
dark energy equation of state parameter w (Late w â M Transitions - LwMT). Here, we compare
the quality of fit of this class of models to cosmological data, with the corresponding quality of fit of
the cosmological constant model (ÎCDM) and some of the best smooth H(z) deformation models
(wCDM, CPL, PEDE). We also perform model selection via the Akaike Information Criterion and
the Bayes factor. We use the full CMB temperature anisotropy spectrum data, the baryon acoustic
oscillations (BAO) data, the Pantheon SnIa data, the SnIa absolute magnitude M as determined by
Cepheid calibrators and the value of the Hubble constant H0 as determined by local SnIa calibrated
using Cepheids. We find that smooth H(z) deformation models perform worse than transition
models for the following reasons: 1) They have a worse fit to low-z geometric probes (BAO and
SnIa data); 2) They favor values of the SnIa absolute magnitude M that are lower as compared
to the value Mc obtained with local Cepheid calibrators at z < 0.01; 3) They tend to worsen the
âŠm,0âÏ8,0 growth tension. We also find that the wâM transition model (LwMT) does not provide
a better quality of fit to cosmological data than a pure M transition model (LMT) where w is fixed
to the ÎCDM value w = â1 at all redshifts. We conclude that the LMT model has significant
statistical advantages over smooth late-time H(z) deformation models in addressing the Hubble
crisis
Survival of dental implants in patients with oral cancer treated by surgery and radiotherapy: a retrospective study
BACKGROUND:
The aim of this retrospective study was to evaluate the survival of dental implants placed after ablative surgery, in patients affected by oral cancer treated with or without radiotherapy.
METHODS:
We collected data for 34 subjects (22 females, 12 males; mean age: 51â±â19) with malignant oral tumors who had been treated with ablative surgery and received dental implant rehabilitation between 2007 and 2012. Postoperative radiation therapy (less than 50 Gy) was delivered before implant placement in 12 patients. A total of 144 titanium implants were placed, at a minimum interval of 12 months, in irradiated and non-irradiated residual bone.
RESULTS:
Implant loss was dependent on the position and location of the implants (Pâ=â0.05-0.1). Moreover, implant survival was dependent on whether the patient had received radiotherapy. This result was highly statistically significant (Pâ<â0.01). Whether the implant was loaded is another highly significant (Pâ<â0.01) factor determinin
Two-neutron transfer reaction mechanisms in C(He,He)C using a realistic three-body He model
The reaction mechanisms of the two-neutron transfer reaction
C(He,He) have been studied at 30 MeV at the TRIUMF ISAC-II
facility using the SHARC charged-particle detector array. Optical potential
parameters have been extracted from the analysis of the elastic scattering
angular distribution. The new potential has been applied to the study of the
transfer angular distribution to the 2 8.32 MeV state in C, using
a realistic 3-body He model and advanced shell model calculations for the
carbon structure, allowing to calculate the relative contributions of the
simultaneous and sequential two-neutron transfer. The reaction model provides a
good description of the 30 MeV data set and shows that the simultaneous process
is the dominant transfer mechanism. Sensitivity tests of optical potential
parameters show that the final results can be considerably affected by the
choice of optical potentials. A reanalysis of data measured previously at 18
MeV however, is not as well described by the same reaction model, suggesting
that one needs to include higher order effects in the reaction mechanism.Comment: 9 pages, 9 figure
The ALMA-ALPAKA survey I: high-resolution CO and [CI] kinematics of star-forming galaxies at z = 0.5-3.5
Spatially-resolved studies of the kinematics of galaxies provide crucial
insights into their assembly and evolution, enabling to infer the properties of
the dark matter halos, derive the impact of feedback on the ISM, characterize
the outflow motions. To date, most of the kinematic studies at z=0.5-3.5 were
obtained using emission lines tracing the warm, ionized gas. However, whether
these provide an exhaustive or only a partial view of the dynamics of galaxies
and of the properties of the ISM is still debated. Complementary insights on
the cold gas kinematics are therefore needed. We present ALPAKA, a project
aimed at gathering high-resolution observations of CO and [CI] emission lines
of star-forming galaxies at z=0.5-3.5 from the ALMA public archive. With 147
hours of total integration time, ALPAKA assembles ~0.25'' observations for 28
star-forming galaxies, the largest sample with spatially-resolved cold gas
kinematics as traced by either CO or [CI] at z>0.5. By combining
multi-wavelength ancillary data, we derive the stellar masses () and
star-formation rates (SFR) for our targets, finding values of M and SFR of 10-3000 M/yr. A large fraction of
ALPAKA galaxies (19/28) lie in overdense regions (clusters, groups, and
protoclusters). We exploit the ALMA data to infer their dynamical state and we
find that 19/28 ALPAKA galaxies are rotating disks, 2 are interacting systems,
while for the remaining 7 sources the classification is uncertain. The disks
have velocity dispersion values that are typically larger in the innermost
regions than in the outskirts, with a median value for the entire disk sample
of 35 km/s. Despite the bias of our sample towards galaxies
hosting very energetic mechanisms, the ALPAKA disks have high ratios of
ordered-to-random motion () with a median value of 9.Comment: 35 pages, 23 figures, 5 tables; submitted to A&A. The data and the
outputs of the kinematic analysis will be made available at
https://alpaka-survey.github.io/index.html once the paper is accepted.
Comments are welcom
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