2,737 research outputs found
Application of asymptotic expansions of maximum likelihood estimators errors to gravitational waves from binary mergers: the single interferometer case
In this paper we describe a new methodology to calculate analytically the
error for a maximum likelihood estimate (MLE) for physical parameters from
Gravitational wave signals. All the existing litterature focuses on the usage
of the Cramer Rao Lower bounds (CRLB) as a mean to approximate the errors for
large signal to noise ratios. We show here how the variance and the bias of a
MLE estimate can be expressed instead in inverse powers of the signal to noise
ratios where the first order in the variance expansion is the CRLB. As an
application we compute the second order of the variance and bias for MLE of
physical parameters from the inspiral phase of binary mergers and for noises of
gravitational wave interferometers . We also compare the improved error
estimate with existing numerical estimates. The value of the second order of
the variance expansions allows to get error predictions closer to what is
observed in numerical simulations. It also predicts correctly the necessary SNR
to approximate the error with the CRLB and provides new insight on the
relationship between waveform properties SNR and estimation errors. For example
the timing match filtering becomes optimal only if the SNR is larger than the
kurtosis of the gravitational wave spectrum
Harvesting traffic-induced vibrations for structural health monitoring of bridges
This paper discusses the development and testing of a renewable energy source for powering wireless sensors used to monitor the structural health of bridges. Traditional power cables or battery replacement are excessively expensive or infeasible in this type of application. An inertial power generator has been developed that can harvest traffic-induced bridge vibrations. Vibrations on bridges have very low acceleration (0.1–0.5 m s _2 ), low frequency (2–30 Hz), and they are non-periodic. A novel parametric frequency-increased generator (PFIG) is developed to address these challenges. The fabricated device can generate a peak power of 57 µW and an average power of 2.3 µW from an input acceleration of 0.54 m s _2 at only 2 Hz. The generator is capable of operating over an unprecedentedly large acceleration (0.54–9.8 m s _2 ) and frequency range (up to 30 Hz) without any modifications or tuning. Its performance was tested along the length of a suspension bridge and it generated 0.5–0.75 µW of average power without manipulation during installation or tuning at each bridge location. A preliminary power conversion system has also been developed.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90794/1/0960-1317_21_10_104005.pd
Unified Multifractal Description of Velocity Increments Statistics in Turbulence: Intermittency and Skewness
The phenomenology of velocity statistics in turbulent flows, up to now,
relates to different models dealing with either signed or unsigned longitudinal
velocity increments, with either inertial or dissipative fluctuations. In this
paper, we are concerned with the complete probability density function (PDF) of
signed longitudinal increments at all scales. First, we focus on the symmetric
part of the PDFs, taking into account the observed departure from scale
invariance induced by dissipation effects. The analysis is then extended to the
asymmetric part of the PDFs, with the specific goal to predict the skewness of
the velocity derivatives. It opens the route to the complete description of all
measurable quantities, for any Reynolds number, and various experimental
conditions. This description is based on a single universal parameter function
D(h) and a universal constant R*.Comment: 13 pages, 3 figures, Extended version, Publishe
Rural men and mental health: their experiences and how they managed
There is a growing awareness that a primary source of information about mental health lies with the consumers. This article reports on a study that interviewed rural men
with the aim of exploring their mental health experiences within a rural environment. The results of the interviews are a number of stories of resilience and survival that
highlight not only the importance of exploring the individuals' perspective of their issues, but also of acknowledging and drawing on their inner strengths. Rural men face a number of challenges that not only increase the risk of mental illness but also decrease the likelihood of them seeking and/or finding professional support. These men's stories, while different from each other, have a common thread of coping. Despite some support from family and friends participants also acknowledged that seeking out professional support could have made the recovery phase easier. Mental health nurses need to be aware, not only of the barrier to professional support but also of the significant resilience that individuals have and how it can be utilised
Binary Models for Marginal Independence
Log-linear models are a classical tool for the analysis of contingency
tables. In particular, the subclass of graphical log-linear models provides a
general framework for modelling conditional independences. However, with the
exception of special structures, marginal independence hypotheses cannot be
accommodated by these traditional models. Focusing on binary variables, we
present a model class that provides a framework for modelling marginal
independences in contingency tables. The approach taken is graphical and draws
on analogies to multivariate Gaussian models for marginal independence. For the
graphical model representation we use bi-directed graphs, which are in the
tradition of path diagrams. We show how the models can be parameterized in a
simple fashion, and how maximum likelihood estimation can be performed using a
version of the Iterated Conditional Fitting algorithm. Finally we consider
combining these models with symmetry restrictions
Design and analysis of fractional factorial experiments from the viewpoint of computational algebraic statistics
We give an expository review of applications of computational algebraic
statistics to design and analysis of fractional factorial experiments based on
our recent works. For the purpose of design, the techniques of Gr\"obner bases
and indicator functions allow us to treat fractional factorial designs without
distinction between regular designs and non-regular designs. For the purpose of
analysis of data from fractional factorial designs, the techniques of Markov
bases allow us to handle discrete observations. Thus the approach of
computational algebraic statistics greatly enlarges the scope of fractional
factorial designs.Comment: 16 page
Recent data indicate that black women are at greater risk of severe morbidity and mortality from postpartum haemorrhage, both before and after adjusting for comorbidity.
Recent data indicate that black women are at greater risk of severe morbidity and mortality from postpartum haemorrhage, both before and after adjusting for comorbidity. Causes of increased risk of severe morbidity and mortality related to postpartum haemorrhage in black women in the USA are poorly understood and warrant further research.
There is a need for tailored maternity services and improved access to care for women from ethnic minorities
DEFENS - Drug Exposure Feedback and Education for Nurses’ Safety: study protocol for a randomized controlled trial
Abstract
Background
Three decades of research findings have documented the health effects of handling hazardous drugs. Oncology nurses are vulnerable due to frequent administration of antineoplastics, low adherence to equipment use, reported barriers to use, and perceived low risk of health effects. No interventions have been tested in a controlled, multi-site trial to increase nurses’ use of protective equipment when handling hazardous drugs. The Drug Exposure Feedback and Education for Nurses’ Safety (DEFENS) study will compare the efficacy of education (control) versus an audit and feedback intervention (treatment) on nurses’ self-reported use of personal protective equipment when handling hazardous drugs. The treatment intervention will include tailored messages based on nurses’ reported barriers to protective equipment use.
Methods/Design
The DEFENS Study is a cluster randomized controlled trial. We are enrolling cancer centers and will recruit nurse participants in April 2015. Eligible cancer centers employ at least 20 eligible registered nurses in the chemotherapy infusion setting and have on-site phlebotomy resources. Eligible participants are nurses who work at least 0.40 full-time equivalent hours in the chemotherapy infusion setting and have not received an antineoplastic drug for a health problem in the past year. An encrypted, user-authenticated website will administer surveys and deliver control and treatment interventions. The primary endpoint is the change in score on nurses’ reports of the Revised Hazardous Drug Handling Questionnaire between baseline and approximately 18 months later. A baseline survey is completed after informed consent and is repeated 18 months later. Nurses in all sites who experience a drug spill will also report incidents as they occur; these reports inform the treatment intervention. Plasma will be obtained at baseline, approximately 18 months later (the primary endpoint), and with drug spill occurrences to measure hazardous drugs levels and to inform the treatment intervention. Potential mediators include knowledge of hazardous drug handling and perceived risk of drug exposure. We will examine whether personal factors and organizational factors moderate the intervention effects.
Trial registration
Clinicaltrials.gov
NCT02283164
, registered 31 October 2014.http://deepblue.lib.umich.edu/bitstream/2027.42/111045/1/13063_2015_Article_674.pd
Adsorption models of hybridization and post-hybridisation behaviour on oligonucleotide microarrays
Analysis of data from an Affymetrix Latin Square spike-in experiment
indicates that measured fluorescence intensities of features on an
oligonucleotide microarray are related to spike-in RNA target concentrations
via a hyperbolic response function, generally identified as a Langmuir
adsorption isotherm. Furthermore the asymptotic signal at high spike-in
concentrations is almost invariably lower for a mismatch feature than for its
partner perfect match feature. We survey a number of theoretical adsorption
models of hybridization at the microarray surface and find that in general they
are unable to explain the differing saturation responses of perfect and
mismatch features. On the other hand, we find that a simple and consistent
explanation can be found in a model in which equilibrium hybridization followed
by partial dissociation of duplexes during the post-hybridization washing
phase.Comment: 26 pages, 6 figures, some rearrangement of sections and some
additions. To appear in J.Phys.(condensed matter
CAR-Net: Clairvoyant Attentive Recurrent Network
We present an interpretable framework for path prediction that leverages
dependencies between agents' behaviors and their spatial navigation
environment. We exploit two sources of information: the past motion trajectory
of the agent of interest and a wide top-view image of the navigation scene. We
propose a Clairvoyant Attentive Recurrent Network (CAR-Net) that learns where
to look in a large image of the scene when solving the path prediction task.
Our method can attend to any area, or combination of areas, within the raw
image (e.g., road intersections) when predicting the trajectory of the agent.
This allows us to visualize fine-grained semantic elements of navigation scenes
that influence the prediction of trajectories. To study the impact of space on
agents' trajectories, we build a new dataset made of top-view images of
hundreds of scenes (Formula One racing tracks) where agents' behaviors are
heavily influenced by known areas in the images (e.g., upcoming turns). CAR-Net
successfully attends to these salient regions. Additionally, CAR-Net reaches
state-of-the-art accuracy on the standard trajectory forecasting benchmark,
Stanford Drone Dataset (SDD). Finally, we show CAR-Net's ability to generalize
to unseen scenes.Comment: The 2nd and 3rd authors contributed equall
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