3,076 research outputs found
Vortex annihilation in the ordering kinetics of the O(2) model
The vortex-vortex and vortex-antivortex correlation functions are determined
for the two-dimensional O(2) model undergoing phase ordering. We find
reasonably good agreement with simulation results for the vortex-vortex
correlation function where there is a short-scaled distance depletion zone due
to the repulsion of like-signed vortices. The vortex-antivortex correlation
function agrees well with simulation results for intermediate and long-scaled
distances. At short-scaled distances the simulations show a depletion zone not
seen in the theory.Comment: 28 pages, REVTeX, submitted to Phys. Rev.
LISA Response Function and Parameter Estimation
We investigate the response function of LISA and consider the adequacy of its
commonly used approximation in the high-frequency range of the observational
band. We concentrate on monochromatic binary systems, such as white dwarf
binaries. We find that above a few mHz the approxmation starts becoming
increasingly inaccurate. The transfer function introduces additional amplitude
and phase modulations in the measured signal that influence parameter estmation
and, if not properly accounted for, lead to losses of signal-to-noise ratio.Comment: 4 pages, 2 figures, amaldi 5 conference proceeding
Facing the LISA Data Analysis Challenge
By being the first observatory to survey the source rich low frequency region
of the gravitational wave spectrum, the Laser Interferometer Space Antenna
(LISA) will revolutionize our understanding of the Cosmos. For the first time
we will be able to detect the gravitational radiation from millions of galactic
binaries, the coalescence of two massive black holes, and the inspirals of
compact objects into massive black holes. The signals from multiple sources in
each class, and possibly others as well, will be simultaneously present in the
data. To achieve the enormous scientific return possible with LISA,
sophisticated data analysis techniques must be developed which can mine the
complex data in an effort to isolate and characterize individual signals. This
proceedings paper very briefly summarizes the challenges associated with
analyzing the LISA data, the current state of affairs, and the necessary next
steps to move forward in addressing the imminent challenges.Comment: 4 pages, no figures, Proceedings paper for the TeV Particle
Astrophysics II conference held Aug 28-31 at the Univ. of Wisconsi
Structural Change in (Economic) Time Series
Methods for detecting structural changes, or change points, in time series
data are widely used in many fields of science and engineering. This chapter
sketches some basic methods for the analysis of structural changes in time
series data. The exposition is confined to retrospective methods for univariate
time series. Several recent methods for dating structural changes are compared
using a time series of oil prices spanning more than 60 years. The methods
broadly agree for the first part of the series up to the mid-1980s, for which
changes are associated with major historical events, but provide somewhat
different solutions thereafter, reflecting a gradual increase in oil prices
that is not well described by a step function. As a further illustration, 1990s
data on the volatility of the Hang Seng stock market index are reanalyzed.Comment: 12 pages, 6 figure
Stability of a Nonequilibrium Interface in a Driven Phase Segregating System
We investigate the dynamics of a nonequilibrium interface between coexisting
phases in a system described by a Cahn-Hilliard equation with an additional
driving term. By means of a matched asymptotic expansion we derive equations
for the interface motion. A linear stability analysis of these equations
results in a condition for the stability of a flat interface. We find that the
stability properties of a flat interface depend on the structure of the driving
term in the original equation.Comment: 14 pages Latex, 1 postscript-figur
HERMIONE: a randomized Phase 2 trial of MM-302 plus trastuzumab versus chemotherapy of physician's choice plus trastuzumab in patients with previously treated, anthracycline-naĂŻve, HER2-positive, locally advanced/metastatic breast cancer.
BackgroundHuman epidermal growth factor receptor 2 (HER2)-positive breast cancer is a particularly aggressive form of the disease, and ultimately progresses in patients with metastases on standard therapies. Anthracyclines, such as doxorubicin, are an effective treatment for HER2-positive breast cancer, particularly when administered in combination with trastuzumab - however, doxorubicin-related cardiotoxicity has limited its use. Many patients are therefore never treated with anthracyclines, even upon disease progression, despite the potential for benefit. MM-302 is a novel, HER2-targeted antibody-liposomal doxorubicin conjugate that specifically targets HER2-overexpressing cells. Preclinical and Phase 1 data suggest that MM-302, as a monotherapy or in combination with trastuzumab, could be effective for managing previously treated, anthracycline-naĂŻve, HER2-positive breast cancer, without the cardiotoxicity observed with free doxorubicin formulations.Methods/designHERMIONE is an open-label, multicenter, randomized (1:1) Phase 2 trial of MM-302 plus trastuzumab versus chemotherapy of physician's choice (gemcitabine, capecitabine, or vinorelbine) plus trastuzumab planned to enroll 250 anthracycline-naĂŻve patients with locally advanced/metastatic HER2-positive breast cancer. Key inclusion criteria are: previous treatment with trastuzumab (with or without pertuzumab) in any setting; refractory or intolerant to pertuzumab (refractory to pertuzumab defined as progression in the locally advanced or metastatic setting, or disease recurrence during or within 12Â months of completing pertuzumab-containing neoadjuvant and/or adjuvant therapy); and disease progression on, or intolerant to, ado-trastuzumab emtansine for locally advanced or metastatic disease. The trial is currently being conducted at sites in the USA, Canada, and Western Europe. Treatment will be administered in 21-day cycles, and will be continued until disease progression or unacceptable toxicity. The primary endpoint is independently assessed progression-free survival (PFS). Tumor response will be assessed every 6Â weeks, and defined according to RECIST v1.1. Secondary endpoints include investigator-assessed PFS, overall survival (OS), OS rates at 6Â months and 1Â year, objective response rates, safety and tolerability, quality of life, and the pharmacokinetic profile of MM-302 plus trastuzumab.DiscussionThe HERMIONE study will evaluate the efficacy and safety of MM-302 plus trastuzumab in patients with refractory HER2-positive advanced/metastatic breast cancer for whom there are no standard of care therapies with a proven survival advantage.Trial registrationClinicaltrials.gov identifier: NCT02213744 . Registration date: 06AUG2014
Detecting extreme mass ratio inspiral events in LISA data using the Hierarchical Algorithm for Clusters and Ridges (HACR)
One of the most exciting prospects for the Laser Interferometer Space Antenna
(LISA) is the detection of gravitational waves from the inspirals of
stellar-mass compact objects into supermassive black holes. Detection of these
sources is an extremely challenging computational problem due to the large
parameter space and low amplitude of the signals. However, recent work has
suggested that the nearest extreme mass ratio inspiral (EMRI) events will be
sufficiently loud that they might be detected using computationally cheap,
template-free techniques, such as a time-frequency analysis. In this paper, we
examine a particular time-frequency algorithm, the Hierarchical Algorithm for
Clusters and Ridges (HACR). This algorithm searches for clusters in a power map
and uses the properties of those clusters to identify signals in the data. We
find that HACR applied to the raw spectrogram performs poorly, but when the
data is binned during the construction of the spectrogram, the algorithm can
detect typical EMRI events at distances of up to Gpc. This is a little
further than the simple Excess Power method that has been considered
previously. We discuss the HACR algorithm, including tuning for single and
multiple sources, and illustrate its performance for detection of typical EMRI
events, and other likely LISA sources, such as white dwarf binaries and
supermassive black hole mergers. We also discuss how HACR cluster properties
could be used for parameter extraction.Comment: 21 pages, 11 figures, submitted to Class. Quantum Gravity. Modified
and shortened in light of referee's comments. Updated results consider tuning
over all three HACR thresholds, and show 10-15% improvement in detection rat
The Role of Mesotocin on Social Bonding in Pinyon Jays
The neuropeptide oxytocin influences mammalian social bonding by facilitating the building and maintenance of parental, sexual, and sameâsex social relationships. However, we do not know whether the function of the avian homologue mesotocin is evolutionarily conserved across birds. While it does influence avian prosocial behavior, mesotocin\u27s role in avian social bonding remains unclear. Here, we investigated whether mesotocin regulates the formation and maintenance of sameâsex social bonding in pinyon jays (Gymnorhinus cyanocephalus), a member of the crow family. We formed squads of four individually housed birds. In the first, âpairâformationâ phase of the experiment, we repeatedly placed pairs of birds from within the squad together in a cage for short periods of time. Prior to entering the cage, we intranasally administered one of three hormone solutions to both members of the pair: mesotocin, oxytocin antagonist, or saline. Pairs received repeated sessions with administration of the same hormone. In the second, âpairâmaintenanceâ phase of the experiment, all four members of the squad were placed together in a large cage, and no hormones were administered. For both phases, we measured the physical proximity between pairs as our proxy for social bonding. We found that, compared with saline, administering mesotocin or oxytocin antagonist did not result in different proximities in either the pairâformation or pairâmaintenance phase of the experiment. Therefore, at the dosages and time frames used here, exogenously introduced mesotocin did not influence sameâsex social bond formation or maintenance. Like oxytocin in mammals, mesotocin regulates avian prosocial behavior; however, unlike oxytocin, we do not have evidence that mesotocin regulates social bonds in birds
Perturbation Expansion in Phase-Ordering Kinetics: II. N-vector Model
The perturbation theory expansion presented earlier to describe the
phase-ordering kinetics in the case of a nonconserved scalar order parameter is
generalized to the case of the -vector model. At lowest order in this
expansion, as in the scalar case, one obtains the theory due to Ohta, Jasnow
and Kawasaki (OJK). The second-order corrections for the nonequilibrium
exponents are worked out explicitly in dimensions and as a function of the
number of components of the order parameter. In the formulation developed
here the corrections to the OJK results are found to go to zero in the large
and limits. Indeed, the large- convergence is exponential.Comment: 20 pages, no figure
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