240 research outputs found
Gravitational waves from inspiralling compact binaries: Energy flux to third post-Newtonian order
The multipolar-post-Minkowskian approach to gravitational radiation is
applied to the problem of the generation of waves by the compact binary
inspiral. We investigate specifically the third post-Newtonian (3PN)
approximation in the total energy flux. The new results are the computation of
the mass quadrupole moment of the binary to the 3PN order, and the current
quadrupole and mass octupole to the 2PN order. Wave tails and tails of tails in
the far zone are included up to the 3.5PN order. The recently derived 3PN
equations of binary motion are used to compute the time-derivatives of the
moments. We find perfect agreement to the 3.5PN order with perturbation
calculations of black holes in the test-mass limit for one body. Technical
inputs in our computation include a model of point particles for describing the
compact objects, and the Hadamard self-field regularization. Because of a
physical incompleteness of the Hadamard regularization at the 3PN order, the
energy flux depends on one unknown physical parameter, which is a combination
of a parameter \lambda in the equations of motion, and a new parameter \theta
coming from the quadrupole moment.Comment: 69 pages, version which includes the correction of an Erratum to be
published in Phys. Rev. D (2005
Gravitational-Wave Inspiral of Compact Binary Systems to 7/2 Post-Newtonian Order
The inspiral of compact binaries, driven by gravitational-radiation reaction,
is investigated through 7/2 post-Newtonian (3.5PN) order beyond the quadrupole
radiation. We outline the derivation of the 3.5PN-accurate binary's
center-of-mass energy and emitted gravitational flux. The analysis consistently
includes the relativistic effects in the binary's equations of motion and
multipole moments, as well as the contributions of tails, and tails of tails,
in the wave zone. However the result is not fully determined because of some
physical incompleteness, present at the 3PN order, of the model of
point-particle and the associated Hadamard-type self-field regularization. The
orbital phase, whose prior knowledge is crucial for searching and analyzing the
inspiral signal, is computed from the standard energy balance argument.Comment: 12 pages, version which includes the correction of an Erratum to be
published in Phys. Rev. D (2005
Connected Surveillance for Detection of Complications After Early Discharge from Bariatric Surgery.
peer reviewedAs part of a bariatric enhanced recovery after surgery (ERAS) program, at-home follow-up using a novel Internet application was used to detect early complications. The study aimed to evaluate the safety and effectiveness of this "connected surveillance" protocol over a 10-day follow-up. Patients were monitored 24/7 by a trained nursing team with daily surgeon review of patient self-reports. Morbidly obese patients (n = 281) underwent OAGB (126, 47.70%) or sleeve gastrectomy (138, 52.3%). Of 264 who completed the study (mean age 40 years [20-66]), 3 (1.1%) underwent revision for early complications; there were 6 (2.1%) readmissions and 22 (8.3%) consultations. In a bariatric surgery ERAS program, "Internet-connected surveillance" proved safe and effective in detecting 100% of early complications, and most patients were satisfied with their care
Long-Term Outcomes After One-Anastomosis Gastric Bypass (OAGB) in Morbidly Obese Patients.
peer reviewed[en] BACKGROUND: One-anastomosis gastric bypass (OAGB) has gradually gained in popularity. Evidence of the validity of the technique and the quality of life in the longer term is scarce. The aim of this study was to retrospectively evaluate the longitudinal (≥ 5 years) safety, weight-loss efficacy, comorbid disease improvement, and quality of life of patients following OAGB.
METHODS: Data from patients who underwent OAGB from January 2009 to December 2011 were retrospectively reviewed. Preoperative clinical characteristics and data through 8 years were analyzed.
RESULTS: A total of 163 patients completed 5 to 8 years of follow-up with a mean age of 41 ± 11.4 years (22-65). Ninety-four patients (57.6%) had undergone prior bariatric surgery (gastric band). Mean body mass index (BMI, kg/m2) at the time of OAGB was 41.2 ± 6.5 (range 30.1-50.6). Twenty-one patients (13.0%) suffered from type 2 diabetes mellitus (T2DM), 59 (36.2%) hypertension, 31 osteoarthritis (19.0%), and 24 had obstructive sleep apnea (14.7%). At 5, 6, 7, and 8 years of follow-up, respective mean BMI reduction was 12.6 (n = 163), 11.8 (n = 100), 10.7 (n = 82), and 8.8 (n = 40). Respective mean excess weight loss was 81.8 ± 23.6%, 75.9 ± 20.8%, 69.1 ± 20.4%, and 62.3 ± 23.4%. All obesity-related comorbidities decreased significantly at follow-up time points. Five patients (3%) underwent laparoscopic reoperation within 90 days after surgery. Incidence of recurrent reflux was 14.0%. At a mean follow-up of 92 months (76-111), improved or greatly improved quality of life was reported by 86.0% of patients.
CONCLUSION: OAGB provided very good weight loss, comorbidity improvement, and quality of life at follow-up of ≥ 5 years
Measuring gravitational effects on antimatter in space
A direct measurement of the gravitational acceleration of antimatter has never been performed to date. Recently, such an experiment has been proposed, using antihydrogen with an atom interferometer and an antihydrogen confinament has been realized at CERN. In alternative we propose an experimental test of the gravitational interaction with antimatter by measuring the branching fraction of the CP violating decay of KL in space. In fact, even if the theoretical Standard Model explains the CPV with the presence of pure phase in the KMC Kobaiashi-Maskava-Cabibbo matrix, ample room is left for contributions by other interactions and forces to generate CPV in the mixing of the neutral K and B mesons. Gravitation is a good candidate and we show that at the altitude of the International Space Station, gravitational effects may change the level of CP violation such that a 5 sigma discrimination may be obtained by collecting the KL produced by the cosmic proton flux within a few years
Recent discovery of Paranthura japonica Richardson, 1909 (Crustacea: Isopod: Paranthuridae) in European marine waters (Arcachon Bay, Bay of Biscay)
The Asiatic isopod Paranthura japonica Richardson, 1909 was collected in 2007 in Arcachon Bay (SW France), where the species occurs in a variety of habitats, both in the intertidal and at shallow depths. This species, native to the Sea of Japan, may have been accidentally introduced in Arcachon Bay with oyster transfers or as fouling on ship hulls
Reconciling MOND and dark matter?
Observations of galaxies suggest a one-to-one analytic relation between the
inferred gravity of dark matter at any radius and the enclosed baryonic mass, a
relation summarized by Milgrom's law of modified Newtonian dynamics (MOND).
However, present-day covariant versions of MOND usually require some additional
fields contributing to the geometry, as well as an additional hot dark matter
component to explain cluster dynamics and cosmology. Here, we envisage a
slightly more mundane explanation, suggesting that dark matter does exist but
is the source of MOND-like phenomenology in galaxies. We assume a canonical
action for dark matter, but also add an interaction term between baryonic
matter, gravity, and dark matter, such that standard matter effectively obeys
the MOND field equation in galaxies. We show that even the simplest realization
of the framework leads to a model which reproduces some phenomenological
predictions of cold dark matter (CDM) and MOND at those scales where these are
most successful. We also devise a more general form of the interaction term,
introducing the medium density as a new order parameter. This allows for new
physical effects which should be amenable to observational tests in the near
future. Hence, this very general framework, which can be furthermore related to
a generalized scalar-tensor theory, opens the way to a possible unification of
the successes of CDM and MOND at different scales.Comment: 9 page
Population Pharmacokinetics of Palbociclib and Its Correlation with Clinical Efficacy and Safety in Patients with Advanced Breast Cancer.
Neutropenia is the most frequent dose-limiting toxicity reported in patients with metastatic breast cancer receiving palbociclib. The objective of this study was to investigate the pharmacokinetic-pharmacodynamic (PK/PD) relationships for toxicity (i.e., absolute neutrophil count, ANC) and efficacy (i.e., progression-free survival, PFS). A semi-mechanistic PK/PD model was used to predict neutrophils' time course using a population approach (NONMEM). Influence of demographic and clinical characteristics was evaluated. Cox proportional hazards models were developed to evaluate the influence of palbociclib PK on PFS. A two-compartment model with first-order absorption and a lag time adequately described the 255 palbociclib concentrations provided by 44 patients. The effect of the co-administration of proton-pump inhibitors in fasting conditions increased palbociclib clearance by 56%. None of the tested covariates affected the PD parameters. Model-based simulations confirmed the concentration-dependent and non-cumulative properties of palbociclib-induced neutropenia, reversible after treatment withdrawal. The ANC nadir occurred approximately at day 24 of each cycle. Cox analyses revealed a trend for better PFS with increasing palbociclib exposure in older patients. By characterizing palbociclib-induced neutropenia, this model offers support to clinicians to rationally optimize treatment management through patient-individualized strategies
Sarcopenia Predicts Early Dose-Limiting Toxicities and Pharmacokinetics of Sorafenib in Patients with Hepatocellular Carcinoma
BACKGROUND: Sorafenib induces frequent dose limiting toxicities (DLT) in patients with advanced hepatocellular carcinoma (HCC). Sarcopenia has been associated with poor performance status and shortened survival in cancer patients. PATIENTS AND METHODS: The characteristics of Child Pugh A cirrhotic patients with HCC receiving sorafenib in our institution were retrospectively analyzed. Sorafenib plasma concentrations were determined at each visit. Toxicities were recorded during the first month of treatment, and sarcopenia was determined from baseline CT-scans. RESULTS: Forty patients (30 males) were included. Eleven (27.5%) were sarcopenic. Eighteen patients (45%) experienced a DLT during the first month of treatment. Sarcopenic patients experienced significantly more DLTs than non-sarcopenic patients did (82% versus 31%, p = 0.005). Grade 3 diarrhea was significantly more frequent in sarcopenic patients than in non-sarcopenic patients (45.5% versus 6.9%, p = 0.01), but not grade 3 hand foot syndrome reaction (9% versus 17.2%, p = 1). On day 28, median sorafenib AUC (n = 17) was significantly higher in sarcopenic patients (102.4 mg/l.h versus 53.7 mg/l.h, p = 0.013). CONCLUSIONS: Among cirrhotic Child Pugh A patients with advanced HCC, sarcopenia predicts sorafenib exposure and the occurrence of DLT within the first month of treatment
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