422 research outputs found
Inherent Holography In Fuzzy Spaces and An N-tropic Approach To The Cosmological Constant Problem
In this letter we show that the noncommutative spaces, and in particular
fuzzy spheres, are natural candidates which explicitly exhibit the holography,
by noting that the smallest physically accessible volume is much larger that
the expected Planckian size. Moreover, we show that fuzzy spheres provide us
with a new approach, ''an -tropic'' approach, to the cosmological constant
problem, though in a Euclidean space-time.Comment: 11 pages, no figures; v3: Presentation improved by adding a
discussion on the Schwarzchild blackhole entropy, the version to appear in
PL
Electronic consent in a COVID-19 vaccine implementation trial in South Africa: Participant perspectives.
The COVID-19 pandemic has warranted modifications to clinical research implementation to ensure adherence to public health and safety measures. Often, this modification has necessitated a deviation from the traditional face-to-face approach to an electronic or hybrid consent process. We assessed the acceptability and preference for electronic consent and explored understanding of the electronic consent information – an outcome which is vital in providing reassurance that consent is provided with full appreciation of the risks and benefits of study participation. In this descriptive study, healthcare professionals (HCPs) were invited, through a database of HCP contacts, snowball sampling and advertisement, to participate in an online survey between 14 July 2021 and 17 September 2021, to explore their experiences of providing electronic consent for enrolment into the largest implementation trial of a COVID vaccine in South Africa (SISONKE Trial). Descriptive analysis was used to characterise respondents and categorical data were expressed as frequencies. The prevalence of recurring responses to open-ended questions allowed for the identification of themes. A total of 1025 HCPs completed the online survey. Access to a COVID-19 vaccine was the strongest motivating factor for enrolment (82.3%) into the SISONKE Trial. Over a third of participants (38.6%) were not able to discuss the study with research staff. While the majority of participants (85.2%) indicated that online consent was acceptable, it was recognised that acceptability was context specific. Although 64% indicated awareness that reporting both a positive COVID test and adverse events were requirements, a significant percentage (32%) did not recall that the reporting period was 2 years. The electronic consent process was easily navigated by educated HCPs with access to electronic devices and data. Vaccine access was the most important motivation for participation, thus raising questions about how voluntary the consent process was and the role of desperation in deciding to participate.Significance:• Navigation of the electronic consent process for participation in a COVID-19 vaccine implementation trial is not a challenge for educated healthcare professionals with access to electronic devices and data. However, technical skills and access to technology may impact the integrity of the informed consent process for lay research participants.• Motivation to join research studies for access to scarce resources impacts negatively on the authenticity of the consent processes, as participation may be informed but not truly voluntary, and is an issue that ethics committees and researchers should address
Transport equation for the photon Wigner operator in non-commutative QED
We derive an exact quantum equation of motion for the photon Wigner operator
in non-commutative QED, which is gauge covariant. In the classical
approximation, this reduces to a simple transport equation which describes the
hard thermal effects in this theory. As an example of the effectiveness of this
method we show that, to leading order, this equation generates in a direct way
the Green amplitudes calculated perturbatively in quantum field theory at high
temperature.Comment: 13 pages, twocolumn revtex4 styl
Classical transport equation in non-commutative QED at high temperature
We show that the high temperature behavior of non-commutative QED may be
simply obtained from Boltzmann transport equations for classical particles. The
transport equation for the charge neutral particle is shown to be
characteristically different from that for the charged particle. These
equations correctly generate, for arbitrary values of the non-commutative
parameter theta, the leading, gauge independent hard thermal loops, arising
from the fermion and the gauge sectors. We briefly discuss the generating
functional of hard thermal amplitudes.Comment: 11 page
Time-Space Noncommutativity in Gravitational Quantum Well scenario
A novel approach to the analysis of the gravitational well problem from a
second quantised description has been discussed. The second quantised formalism
enables us to study the effect of time space noncommutativity in the
gravitational well scenario which is hitherto unavailable in the literature.
The corresponding first quantized theory reveals a leading order perturbation
term of noncommutative origin. Latest experimental findings are used to
estimate an upper bound on the time--space noncommutative parameter. Our
results are found to be consistent with the order of magnitude estimations of
other NC parameters reported earlier.Comment: 7 pages, revTe
Noncommutative massive Thirring model in three-dimensional spacetime
We evaluate the noncommutative Chern-Simons action induced by fermions
interacting with an Abelian gauge field in a noncommutative massive Thirring
model in (2+1)-dimensional spacetime. This calculation is performed in the
Dirac and Majorana representations. We observe that in Majorana representation
when goes to zero we do not have induced Chern-Simons term in the
dimensional regularization scheme.Comment: Accepted to Phys. Rev. D; 9 pages, Revtex4, no figures, references
added, minor improvements, Eq.31 correcte
Noncommutative quantum mechanics and Bohm's ontological interpretation
We carry out an investigation into the possibility of developing a Bohmian
interpretation based on the continuous motion of point particles for
noncommutative quantum mechanics. The conditions for such an interpretation to
be consistent are determined, and the implications of its adoption for
noncommutativity are discussed. A Bohmian analysis of the noncommutative
harmonic oscillator is carried out in detail. By studying the particle motion
in the oscillator orbits, we show that small-scale physics can have influence
at large scales, something similar to the IR-UV mixing
Non-Hermitian quantum mechanics in non-commutative space
We study non Hermitian quantum systems in noncommutative space as well as a
\cal{PT}-symmetric deformation of this space. Specifically, a
\mathcal{PT}-symmetric harmonic oscillator together with iC(x_1+x_2)
interaction is discussed in this space and solutions are obtained. It is shown
that in the \cal{PT} deformed noncommutative space the Hamiltonian may or may
not possess real eigenvalues depending on the choice of the noncommutative
parameters. However, it is shown that in standard noncommutative space, the
iC(x_1+x_2) interaction generates only real eigenvalues despite the fact that
the Hamiltonian is not \mathcal{PT}-symmetric. A complex interacting
anisotropic oscillator system has also been discussed.Comment: 5 pages, revised versio
First-Line Nivolumab in Stage IV or Recurrent Non-Small-Cell Lung Cancer.
Nivolumab has been associated with longer overall survival than docetaxel among patients with previously treated non-small-cell lung cancer (NSCLC). In an open-label phase 3 trial, we compared first-line nivolumab with chemotherapy in patients with programmed death ligand 1 (PD-L1)-positive NSCLC.
We randomly assigned, in a 1:1 ratio, patients with untreated stage IV or recurrent NSCLC and a PD-L1 tumor-expression level of 1% or more to receive nivolumab (administered intravenously at a dose of 3 mg per kilogram of body weight once every 2 weeks) or platinum-based chemotherapy (administered once every 3 weeks for up to six cycles). Patients receiving chemotherapy could cross over to receive nivolumab at the time of disease progression. The primary end point was progression-free survival, as assessed by means of blinded independent central review, among patients with a PD-L1 expression level of 5% or more.
Among the 423 patients with a PD-L1 expression level of 5% or more, the median progression-free survival was 4.2 months with nivolumab versus 5.9 months with chemotherapy (hazard ratio for disease progression or death, 1.15; 95% confidence interval [CI], 0.91 to 1.45; P=0.25), and the median overall survival was 14.4 months versus 13.2 months (hazard ratio for death, 1.02; 95% CI, 0.80 to 1.30). A total of 128 of 212 patients (60%) in the chemotherapy group received nivolumab as subsequent therapy. Treatment-related adverse events of any grade occurred in 71% of the patients who received nivolumab and in 92% of those who received chemotherapy. Treatment-related adverse events of grade 3 or 4 occurred in 18% of the patients who received nivolumab and in 51% of those who received chemotherapy.
Nivolumab was not associated with significantly longer progression-free survival than chemotherapy among patients with previously untreated stage IV or recurrent NSCLC with a PD-L1 expression level of 5% or more. Overall survival was similar between groups. Nivolumab had a favorable safety profile, as compared with chemotherapy, with no new or unexpected safety signals. (Funded by Bristol-Myers Squibb and others; CheckMate 026 ClinicalTrials.gov number, NCT02041533 .)
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