271 research outputs found
Finding high-order analytic post-Newtonian parameters from a high-precision numerical self-force calculation
We present a novel analytic extraction of high-order post-Newtonian (pN)
parameters that govern quasi-circular binary systems. Coefficients in the pN
expansion of the energy of a binary system can be found from corresponding
coefficients in an extreme-mass-ratio inspiral (EMRI) computation of the change
in the redshift factor of a circular orbit at fixed angular
velocity. Remarkably, by computing this essentially gauge-invariant quantity to
accuracy greater than one part in , and by assuming that a subset of
pN coefficients are rational numbers or products of and a rational, we
obtain the exact analytic coefficients. We find the previously unexpected
result that the post-Newtonian expansion of (and of the change
in the angular velocity at fixed redshift factor) have
conservative terms at half-integral pN order beginning with a 5.5 pN term. This
implies the existence of a corresponding 5.5 pN term in the expansion of the
energy of a binary system.
Coefficients in the pN series that do not belong to the subset just described
are obtained to accuracy better than 1 part in at th pN
order. We work in a radiation gauge, finding the radiative part of the metric
perturbation from the gauge-invariant Weyl scalar via a Hertz
potential. We use mode-sum renormalization, and find high-order renormalization
coefficients by matching a series in to the large- behavior of
the expression for . The non-radiative parts of the perturbed metric
associated with changes in mass and angular momentum are calculated in the
Schwarzschild gauge
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The utility of diagnostic selective nerve root blocks in the management of patients with lumbar radiculopathy: a systematic review.
OBJECTIVE: Lumbar radiculopathy (LR) often manifests as pain in the lower back radiating into one leg (sciatica). Unsuccessful back surgery is associated with significant healthcare costs and risks to patients. This review aims to examine the diagnostic accuracy of selective nerve root blocks (SNRBs) to identify patients most likely to benefit from lumbar decompression surgery. DESIGN: Systematic review of diagnostic test accuracy studies. ELIGIBILITY CRITERIA: Primary research articles using a patient population with low back pain and symptoms in the leg, SNRB administered under radiological guidance as index test, and any reported reference standard for the diagnosis of LR. INFORMATION SOURCES: MEDLINE (Ovid), MEDLINE In-Process & Other Non-Indexed Citations, EMBASE, Science Citation Index, Biosis, LILACS, Dissertation abstracts and National Technical Information Service from inception to 2018. METHODS: Risk of bias and applicability was assessed using the QUADAS-2 tool. We performed random-effects logistic regression to meta-analyse studies grouped by reference standard. RESULTS: 6 studies (341 patients) were included in this review. All studies were judged at high risk of bias. There was substantial heterogeneity across studies in sensitivity (range 57%-100%) and specificity (10%-86%) estimates. Four studies were diagnostic cohort studies that used either intraoperative findings during surgery (pooled sensitivity: 93.5% [95% CI 84.0 to 97.6]; specificity: 50.0% [16.8 to 83.2]) or 'outcome following surgery' as the reference standard (pooled sensitivity: 90.9% [83.1 to 95.3]; specificity 22.0% [7.4 to 49.9]). Two studies had a within-patient case-control study design, but results were not pooled because different types of control injections were used. CONCLUSIONS: We found limited evidence which was of low methodological quality indicating that the diagnostic accuracy of SNRB is uncertain and that specificity in particular may be low. SNRB is a safe test with a low risk of clinically significant complications, but it remains unclear whether the additional diagnostic information it provides justifies the cost of the test.National Institute for Health Research Health Technology Assessment programme grant (project number 09/111/01)
Dilute, derivatise and shoot: Measurement of urinary free metanephrines and catecholamines as ethyl derivatives by LC-MSMS
This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/
This author accepted manuscript is made available following 24 month embargo from date of publication (Sept 2017) in accordance with the publisherâs archiving policyBackground
The measurement of catecholamines and their metabolites in either urine or plasma is an important diagnostic test used to exclude the presence of neuroendocrine tumours. Because of weak chromatographic retention and potential ion-suppression, reverse-phase LC-MSMS is not ideal for analysis of these polar molecules. Here, we investigate derivatisation by ethylation as an alternative approach.
Methods
A simple and rapid method involving acetaldehyde and a reducing agent was used to convert urine free metanephrines and catecholamines, and their deuterated analogues as internal standards, to mono-ethyl or diethyl- derivatives. Using an Agilent 6460 triple-quadrupole mass spectrometer, precursor and product ion mass spectra were recorded to allow comparison of multiple reaction monitoring methods for both derivatised and non-derivatised analytes under reverse-phase LC-MSMS conditions with positive electrospray ionization.
Results
Conversion of biogenic amines to less polar ethyl derivatives increased their mass and enhanced the intensity of their molecular ions and fragments. Ethylation also improved the chromatographic properties of the amines, with greater retention and elution from reverse-phase HPLC columns with a methanol or acetonitrile gradient. The signal response of tandem mass spectrometric detection was increased up to 50-fold for ethyl metanephrines compared to non-derivatised compounds. This increase allowed for the omission of solid-phase extraction of urine as a clean-up step prior to analysis. The âdilute-derivatise-shootâ method maintained analytical performance with respect to between-run imprecision (CV < 6%) and accuracy in an external quality assurance program. Gender-related ranges for free metanephrines in early-morning spot urines, collected from adult patients, were similar using either derivatised or non-derivatised samples.
Conclusions
The LC-MSMS detection of free urine biogenic amines can be greatly enhanced by ethyl derivatisation, which is easy and rapid to perform. Advantages include improved chromatography and lower limits of quantitation, that negate the requirement for solid-phase clean-up of urine prior to analysis. A disadvantage is the potential toxicity of the derivatising agents used if they are not handled appropriately
A phase II study of dacetuzumab (SGN-40) in patients with relapsed diffuse large B-cell lymphoma (DLBCL) and correlative analyses of patient-specific factors
BACKGROUND: Patients with DLBCL who are ineligible for or have relapsed after aggressive salvage chemotherapy have a poor prognosis. CD40 is expressed on multiple B-cell neoplasms including DLBCL and is a potential target for immunotherapy. Dacetuzumab (SGN-40), a non-blocking, partial agonist, humanized IgG1, anti-CD40 monoclonal antibody, has previously demonstrated anti-lymphoma activity in a phase I study. METHODS: A phase II study was undertaken to evaluate the rate and duration of objective responses and safety of single-agent dacetuzumab in relapsed DLBCL. Forty-six adult patients with relapsed/refractory DLBCL received up to 12Â cycles of intravenous dacetuzumab using intrapatient dose-escalation to a target dose of 8Â mg/kg/week in an initial 5-week cycle, followed by 4-week cycles of 8Â mg/kg/week. Study endpoints included rate and duration of objective responses, safety, survival, pharmacokinetics, immunogenicity, and exploratory correlative studies. RESULTS: Overall response rate was 9% and disease control rate (complete remissionâ+âpartial remissionâ+âstable disease) was 37%. Common non-hematologic adverse events (AEs) included fatigue, headache, chills, fever, and nausea. The most frequent Grade 3â4 non-hematologic AE was deep venous thrombosis (3 patients). Grade 3â4 lymphopenia (41%), neutropenia (13%), or thrombocytopenia (19%) occurred without associated infection or bleeding. Reversible ocular events, including conjunctivitis and ocular hyperemia, occurred in 8 patients (17%). Patient-specific factors, including Fc-gamma-RIIIa polymorphism, did not appear to correlate with antitumor activity. CONCLUSIONS: Single-agent dacetuzumab has modest activity and manageable toxicity in unselected patients with relapsed DLBCL. Combination regimens and robust methods of patient selection may be necessary for further development. TRIAL REGISTRATION: ClinicalTrials.gov identifier NCT00435916
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Evaluating Cumulative Ecosystem Response to Restoration Projects in the Columbia River Estuary, Annual Report 2005
This report is the second annual report of a six-year project to evaluate the cumulative effects of habitat restoration projects in the Columbia River Estuary, conducted by Pacific Northwest National Laboratory's Marine Sciences Laboratory, NOAA's National Marine Fisheries Service Pt. Adams Biological Field Station, and the Columbia River Estuary Study Taskforce for the US Army Corps of Engineers. In 2005, baseline data were collected on two restoration sites and two associated reference sites in the Columbia River estuary. The sites represent two habitat types of the estuary--brackish marsh and freshwater swamp--that have sustained substantial losses in area and that may play important roles for salmonids. Baseline data collected included vegetation and elevation surveys, above and below-ground biomass, water depth and temperature, nutrient flux, fish species composition, and channel geometry. Following baseline data collection, three kinds of restoration actions for hydrological reconnection were implemented in several locations on the sites: tidegate replacements (2) at Vera Slough, near the city of Astoria in Oregon State, and culvert replacements (2) and dike breaches (3) at Kandoll Farm in the Grays River watershed in Washington State. Limited post-restoration data were collected: photo points, nutrient flux, water depth and temperature, and channel cross-sections. In subsequent work, this and additional post-restoration data will be used in conjunction with data from other sites to estimate net effects of hydrological reconnection restoration projects throughout the estuary. This project is establishing methods for evaluating the effectiveness of individual projects and a framework for assessing estuary-wide cumulative effects including a protocol manual for monitoring restoration and reference sites
Confrontational Behavior and Escalation to War 1816-1980: A Research Plan
The understanding of international war, like many complex social events, may be - and has been - ap proached from a range of theoretical perspectives and via a variety of research strategies. Outside of the work of Bloch (1898), Sorokin (1936), Richardson (1941), and Wright (1942), however, there was little re search of a scientific nature until the mid-1960s. And while these past fifteen years have certainly not given us a compelling theory of international war, they have seen a steady growth in cumulative knowledge regar ding the correlates of war. These results, despite the expected mix of inconsistencies and anomalies, provide us with some sense of the factors that are most consistently associated with war over the last century and a half, along with some tentative insights into the rising and declining potency of these factors.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68556/2/10.1177_002234338201900104.pd
An integrative framework for the appraisal of coloration in nature
The world in color presents a dazzling dimension of phenotypic variation. Biological interest in this variation has burgeoned, due to both increased means for quantifying spectral information and heightened appreciation for how animals view the world differently than humans. Effective study of color traits is challenged by how to best quantify visual perception in nonhuman species. This requires consideration of at least visual physiology but ultimately also the neural processes underlying perception. Our knowledge of color perception is founded largely on the principles gained from human psychophysics that have proven generalizable based on comparative studies in select animal models. Appreciation of these principles, their empirical foundation, and the reasonable limits to their applicability is crucial to reaching informed conclusions in color research. In this article, we seek a common intellectual basis for the study of color in nature. We first discuss the key perceptual principles, namely, retinal photoreception, sensory channels, opponent processing, color constancy, and receptor noise. We then draw on this basis to inform an analytical framework driven by the research question in relation to identifiable viewers and visual tasks of interest. Consideration of the limits to perceptual inference guides two primary decisions: first, whether a sensory-based approach is necessary and justified and, second, whether the visual task refers to perceptual distance or discriminability. We outline informed approaches in each situation and discuss key challenges for future progress, focusing particularly on how animals perceive color. Given that animal behavior serves as both the basic unit of psychophysics and the ultimate driver of color ecology/evolution, behavioral data are critical to reconciling knowledge across the schools of color research
Deep Investigation of Neutral Gas Origins (DINGO): HI stacking experiments with early science data
We present early science results from Deep Investigation of Neutral Gas
Origins (DINGO), an HI survey using the Australian Square Kilometre Array
Pathfinder (ASKAP). Using ASKAP sub-arrays available during its commissioning
phase, DINGO early science data were taken over 60 deg of the
Galaxy And Mass Assembly (GAMA) 23 h region with 35.5 hr integration time. We
make direct detections of six known and one new sources at . Using HI
spectral stacking, we investigate the HI gas content of galaxies at for different galaxy colours. The results show that galaxy morphology
based on optical colour is strongly linked to HI gas properties. To examine
environmental impacts on the HI gas content of galaxies, three sub-samples are
made based on the GAMA group catalogue. The average HI mass of group central
galaxies is larger than those of satellite and isolated galaxies, but with a
lower HI gas fraction. We derive a variety of HI scaling relations for physical
properties of our sample, including stellar mass, stellar mass surface density,
colour, specific star formation rate, and halo mass. We find that the
derived HI scaling relations are comparable to other published results, with
consistent trends also observed to 0.5 dex lower limits in stellar mass
and stellar surface density. The cosmic HI densities derived from our data are
consistent with other published values at similar redshifts. DINGO early
science highlights the power of HI spectral stacking techniques with ASKAP.Comment: 27 pages, 25 figures, 10 tables, accepted for publication in MNRA
Deep Investigation of Neutral Gas Origins (DINGO): HI stacking experiments with early science data
We present early science results from Deep Investigation of Neutral Gas Origins (DINGO), an H I survey using the Australian Square Kilometre Array Pathfinder (ASKAP). Using ASKAP subarrays available during its commissioning phase, DINGO early science data were taken over âŒ60 deg2 of the Galaxy And Mass Assembly (GAMA) 23 h region with 35.5 h integration time. We make direct detections of six known and one new sources at z \u3c 0.01. Using H I spectral stacking, we investigate the H I gas content of galaxies at 0.04 \u3c z \u3c 0.09 for different galaxy colours. The results show that galaxy morphology based on optical colour is strongly linked to H I gas properties. To examine environmental impacts on the H I gas content of galaxies, three subsamples are made based on the GAMA group catalogue. The average H I mass of group central galaxies is larger than those of satellite and isolated galaxies, but with a lower H I gas fraction. We derive a variety of H I scaling relations for physical properties of our sample, including stellar mass, stellar mass surface density, NUV â r colour, specific star formation rate, and halo mass. We find that the derived H I scaling relations are comparable to other published results, with consistent trends also observed to âŒ0.5 dex lower limits in stellar mass and stellar surface density. The cosmic H I densities derived from our data are consistent with other published values at similar redshifts. DINGO early science highlights the power of H I spectral stacking techniques with ASKA
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Evaluating Cumulative Ecosystem Response to Restoration Projects in the Columbia River Estuary, Annual Report 2006
This report is the third annual report of a six-year project to evaluate the cumulative effects of habitat restoration action in the Columbia River Estuary (CRE). The project is being conducted for the U.S. Army Corps of Engineers (Corps) by the Marine Sciences Laboratory of the Pacific Northwest National Laboratory, the Pt. Adams Biological Field Station of the National Marine Fisheries Service, and the Columbia River Estuary Study Taskforce. Measurement of the cumulative effects of ecological restoration projects in the Columbia River estuary is a formidable task because of the size and complexity of the estuarine landscape and the meta-populations of salmonids in the Columbia River basin. Despite the challenges presented by this system, developing and implementing appropriate indicators and methods to measure cumulative effects is the best way to enable estuary managers to track the overall effectiveness of investments in estuarine restoration projects. This project is developing methods to quantify the cumulative effects of multiple restoration activities in the CRE. The overall objectives of the 2006 study were to continue to develop techniques to assess cumulative effects, refine the standard monitoring protocols, and initiate development of an adaptive management system for Corps of Engineersâ habitat restoration monitoring efforts in the CRE. (The adaptive management effort will be reported at a later date.) Field studies during 2006 were conducted in tidal freshwater at Kandoll Farm on the lower Grays River and tidal brackish water at Vera Slough on Youngs Bay. Within each of area, we sampled one natural reference site and one restoration site. We addressed the overall objectives with field work in 2006 that, coupled with previous field data, had specific objectives and resulted in some important findings that are summarized here by chapter in this report. Each chapter of the report contains data on particular monitored variables for pre- and post-restoration conditions at both the Kandoll and Vera study areas
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