41 research outputs found
On the Heisenberg invariance and the Elliptic Poisson tensors
We study different algebraic and geometric properties of Heisenberg invariant
Poisson polynomial quadratic algebras. We show that these algebras are
unimodular. The elliptic Sklyanin-Odesskii-Feigin Poisson algebras
are the main important example. We classify all quadratic
invariant Poisson tensors on with and show that
for they coincide with the elliptic Sklyanin-Odesskii-Feigin Poisson
algebras or with their certain degenerations.Comment: 14 pages, no figures, minor revision, typos correcte
Time-Frequency Transfer with Quantum Fields
Clock synchronisation relies on time-frequency transfer procedures which
involve quantum fields. We use the conformal symmetry of such fields to define
as quantum operators the time and frequency exchanged in transfer procedures
and to describe their transformation under transformations to inertial or
accelerated frames. We show that the classical laws of relativity are changed
when brought in the framework of quantum theory.Comment: 4 page
Appropriateness of Imaging for Low-Risk Prostate Cancer-Real World Data from the Pennsylvania Urologic Regional Collaboration (PURC)
Imaging for prostate cancer defines the extent of disease. Guidelines recommend against imaging low-risk prostate cancer patients with a computed tomography (CT) scan or bone scan due to the low probability of metastasis. We reviewed imaging performed for men diagnosed with low-risk prostate cancer across the Pennsylvania Urologic Regional Collaborative (PURC), a physician-led data sharing and quality improvement collaborative. The data of 10 practices were queried regarding the imaging performed in men diagnosed with prostate cancer from 2015 to 2022. The cohort included 13,122 patients with 3502 (27%) low-risk, 2364 (18%) favorable intermediate-risk, 3585 (27%) unfavorable intermediate-risk, and 3671 (28%) high-risk prostate cancer, based on the AUA guidelines. Amongst the low-risk patients, imaging utilization included pelvic MRI (59.7%), bone scan (17.8%), CT (16.0%), and PET-based imaging (0.5%). Redundant imaging occurred in 1022 patients (29.2%). There was variability among the PURC sites for imaging used in the low-risk patients, and iterative education reduced the need for CT and bone scans. Approximately 15% of low-risk patients had staging imaging performed using either a CT or bone scan, and redundant imaging occurred in almost one-third of men. Such data underscore the need for continued guideline-based education to optimize the stewardship of resources and reduce unnecessary costs to the healthcare system
Movement and Fluctuations of the Vacuum
Quantum fields possess zero-point or vacuum fluctuations which induce
mechanical effects, namely generalised Casimir forces, on any scatterer.
Symmetries of vacuum therefore raise fundamental questions when confronted
with the principle of relativity of motion in vacuum. The specific case of
uniformly accelerated motion is particularly interesting, in connection with
the much debated question of the appearance of vacuum in accelerated frames.
The choice of Rindler representation, commonly used in General Relativity,
transforms vacuum fluctuations into thermal fluctuations, raising difficulties
of interpretation. In contrast, the conformal representation of uniformly
accelerated frames fits the symmetry properties of field propagation and
quantum vacuum and thus leads to extend the principle of relativity of motion
to uniform accelerations.
Mirrors moving in vacuum with a non uniform acceleration are known to
radiate. The associated radiation reaction force is directly connected to
fluctuating forces felt by motionless mirrors through fluctuation-dissipation
relations. Scatterers in vacuum undergo a quantum Brownian motion which
describes irreducible quantum fluctuations. Vacuum fluctuations impose ultimate
limitations on measurements of position in space-time, and thus challenge the
very concept of space-time localisation within a quantum framework.
For test masses greater than Planck mass, the ultimate limit in localisation
is determined by gravitational vacuum fluctuations. Not only positions in
space-time, but also geodesic distances, behave as quantum variables,
reflecting the necessary quantum nature of an underlying geometry.Comment: 17 pages, to appear in Reports on Progress in Physic
Multiple-Quantum Spin Dynamics of Entanglement
Dynamics of entanglement is investigated on the basis of exactly solvable
models of multiple-quantum (MQ) NMR spin dynamics. It is shown that the time
evolution of MQ coherences of systems of coupled nuclear spins in solids is
directly connected with dynamics of the quantum entanglement. We studied
analytically dynamics of entangled states for two- and three-spin systems
coupled by the dipole-dipole interaction. In this case dynamics of the quantum
entanglement is uniquely determined by the time evolution of MQ coherences of
the second order. The real part of the density matrix describing MQ dynamics in
solids is responsible for MQ coherences of the zeroth order while its imaginary
part is responsible for the second order. Thus, one can conclude that dynamics
of the entanglement is connected with transitions from the real part of the
density matrix to the imaginary one and vice versa. A pure state which
generalizes the GHZ and W states is found. Different measures of the
entanglement of this state are analyzed for three-partite systems.Comment: 11 pages, 4 figure
Protocol of a Multicentre Randomised Controlled Trial Assessing Transperineal Prostate Biopsy to Reduce Infectiouscomplications
Introduction Approximately one million prostate biopsies are performed annually in the USA, and most are performed using a transrectal approach under local anaesthesia. The risk of postbiopsy infection is increasing due to increasing antibiotic resistance of rectal flora. Single-centre studies suggest that a clean, percutaneous transperineal approach to prostate biopsy may have a lower risk of infection. To date, there is no high-level evidence comparing transperineal versus transrectal prostate biopsy. We hypothesise that transperineal versus transrectal prostate biopsy under local anaesthesia has a significantly lower risk of infection, similar pain/discomfort levels and comparable detection of non-low-grade prostate cancer.
Methods and analysis We will perform a multicentre, prospective randomised clinical trial to compare transperineal versus transrectal prostate biopsy for elevated prostate-specific antigen in the first biopsy, prior negative biopsy and active surveillance biopsy setting. Prostate MRI will be performed prior to biopsy, and targeted biopsy will be conducted for suspicious MRI lesions in addition to systematic biopsy (12 cores). Approximately 1700 men will be recruited and randomised in a 1:1 ratio to transperineal versus transrectal biopsy. A streamlined design to collect data and to determine trial eligibility along with the two-stage consent process will be used to facilitate subject recruitment and retention. The primary outcome is postbiopsy infection, and secondary outcomes include other adverse events (bleeding, urinary retention), pain/ discomfort/anxiety and critically, detection of non-low-grade (grade group â„2) prostate cancer.
Ethics and dissemination The Institutional Review Board of the Biomedical Research Alliance of New York approved the research protocol (protocol number #18-02-365, approved 20 April 2020). The results of the trial will be presented at scientific conferences and published in peer-reviewed medical journals.
Trial registration number NCT04815876
Prostate Cancer Biochemical Recurrence Rates After Robotic-Assisted Laparoscopic Radical Prostatectomy
Background and Objectives:
To determine prostate cancer biochemical recurrence rates with respect to surgical margin (SM) status for patients undergoing robotic-assisted laparoscopic radical prostatectomy (RALP).
Methods:
IRB-approved radical prostatectomy database was queried. Patients were stratified as low, intermediate, and high risk according to DâAmico\u27s risk classification. Postoperative prostate-specific antigen (PSA) values were obtained every 3 mo for the first year, then biannually and annually thereafter. Biochemical recurrence was defined as â„0.2ng/mL. Patients receiving adjuvant or salvage treatment were included. Positive surgical margin was defined as presence of cancer cells at inked resection margin in the final specimen. Margin presence (negative/positive), margin multiplicity (single/multiple), and margin length (â€3mm focal and \u3e3mm extensive) were noted. Kaplan-Meier curves of biochemical recurrence-free survival (BRFS) as a function of SM were generated. Forward stepwise multivariate Cox regression was performed, with preoperative PSA, Gleason score, pathologic stage, prostate gland weight, and SM as covariates.
Results:
At our institution, 1437 patients underwent RALP (2003-2009). Of these, 1159 had sufficient data and were included in our analysis. Mean follow-up was 16 mo. Kaplan-Meier curves demonstrated significant increase in BRFS in low-risk and intermediate-risk groups with negative SM. Overall BRFS at 5 y was 72%. Gleason score, pathologic stage, and SM status were significant prognostic factors in multivariate analysis.
Conclusions:
Negative surgical margins resulted in lower biochemical recurrence rates for low-risk and intermediate-risk groups. Multifocal and longer positive margins were associated with higher biochemical recurrence rates compared with unifocal and shorter positive margins. Documenting biochemical recurrence rates for RALP is important, because this treatment for localized prostate cancer is validated