7 research outputs found
Upper limits on the strength of periodic gravitational waves from PSR J1939+2134
The first science run of the LIGO and GEO gravitational wave detectors
presented the opportunity to test methods of searching for gravitational waves
from known pulsars. Here we present new direct upper limits on the strength of
waves from the pulsar PSR J1939+2134 using two independent analysis methods,
one in the frequency domain using frequentist statistics and one in the time
domain using Bayesian inference. Both methods show that the strain amplitude at
Earth from this pulsar is less than a few times .Comment: 7 pages, 1 figure, to appear in the Proceedings of the 5th Edoardo
Amaldi Conference on Gravitational Waves, Tirrenia, Pisa, Italy, 6-11 July
200
Improving the sensitivity to gravitational-wave sources by modifying the input-output optics of advanced interferometers
We study frequency dependent (FD) input-output schemes for signal-recycling
interferometers, the baseline design of Advanced LIGO and the current
configuration of GEO 600. Complementary to a recent proposal by Harms et al. to
use FD input squeezing and ordinary homodyne detection, we explore a scheme
which uses ordinary squeezed vacuum, but FD readout. Both schemes, which are
sub-optimal among all possible input-output schemes, provide a global noise
suppression by the power squeeze factor, while being realizable by using
detuned Fabry-Perot cavities as input/output filters. At high frequencies, the
two schemes are shown to be equivalent, while at low frequencies our scheme
gives better performance than that of Harms et al., and is nearly fully
optimal. We then study the sensitivity improvement achievable by these schemes
in Advanced LIGO era (with 30-m filter cavities and current estimates of
filter-mirror losses and thermal noise), for neutron star binary inspirals, and
for narrowband GW sources such as low-mass X-ray binaries and known radio
pulsars. Optical losses are shown to be a major obstacle for the actual
implementation of these techniques in Advanced LIGO. On time scales of
third-generation interferometers, like EURO/LIGO-III (~2012), with
kilometer-scale filter cavities, a signal-recycling interferometer with the FD
readout scheme explored in this paper can have performances comparable to
existing proposals. [abridged]Comment: Figs. 9 and 12 corrected; Appendix added for narrowband data analysi
The State of the Dry Forest Zone and its Communities
94 p.The Dry Forest Zone is a region of eastern Oregon
and northern California with challenging
market conditions and high levels of poverty
and unemployment. However, local entrepreneurship,
collaboration, and commitment to integrated
economic development and natural resource management
in the zone are strong. In the past decade,
the scope of community-based nonprofits, integrated
biomass utilization businesses, and new networks
has increased, fostering sustainable forest stewardship
at an increasingly regional scale. The geography and climate of the zone support dry
forests of pine and mixed conifer with fire regimes
that are departed from their historical range of variability.
These forests are prone to wildfire hazards
and in need of active management to restore more
diverse and variable-aged structures. As 68 percent
of the land in the zone is public, the communities
of this region rely on the economic and ecological
productivity of these federal forests. The number of
sawmills that once provided high levels of primary
processing capacity and employment has shrunk to nine mills in the zone. More forest-related employment
is now forestry support work, including activities
such as firefighting, pest control, and thinning.
Poverty and unemployment have increased, with
estimated poverty levels in 2007 of over 15 percent
in ten of the fifteen counties. Through the Dry Forest
Zone project, we have an opportunity to build on
the local strengths of this region and overcome these
ecological and socioeconomic challenges.Financial support was provided the U.S. Endowment for Forestry and Communities,
USDA Rural Development, and the Ford Foundation
Detektion von Apnoeereignissen aus Schnarchsignalen
Zur ambulanten Differenzierung zwischen primärem Schnarchen und obstruktiver Schlafapnoe wird eine kostengünstige und einfach durchführbare Diagnostik benötigt. Eine Quantifizierung der Schnarchlautstärke ist bisher nicht zufriedenstellend möglich, führt jedoch typischerweise den Patienten zum HNO-Arzt. Das Ziel dieser Studie war es, anhand von während des Schlafes aufgezeichneten Atemgeräuschen eine Software zu entwickeln, die Schnarchgeräusche quantifiziert und Atempausen detektiert.Auf der Basis von 89 Ganz-Nacht-Datensätzen von 49 Personen wurde ein Algorithmus entwickelt, der das gesamte Audiosignal mit speziellen Filtersystemen nach charakteristischen Atemgeräuschen durchsucht. Folgt auf eine Geräuschpause von mindestens 10 sec Länge ein typisches Öffnungsgeräusch, so wird diese Stelle als Apnoe-ähnliches Ereignis erkannt. Zur Ermittlung von Sensitivität und Spezifität der Software wurden die Ergebnisse dann mit den in der simultanen Polysomnographie gefundenen Atempausen verglichen. Das Ausmaß der Schnarchgeräusche wurde bezüglich ihrer Intensität und Häufigkeit quantifiziert.Zur Erzielung einer optimalen Apnoeerkennung waren Bandpassfilter und adaptive Schwellenwertbestimmung erforderlich. Bei einem Filterwert von 11 Sekunden wurde eine Sensitivität von 81,5% und eine Spezifität von 48,5% erreicht. Vereinfachte Hochpassfilter ergaben eine deutlich schlechtere Genauigkeit. Für die Beurteilung des Schnarchens wurde ein Index aus mittlerer Intensität und Schnarchhäufigkeit errechnet.Die Analyse von Atemgeräuschen im Schlaf kann erfolgreich zum Apnoescreening und zur Quantifizierung der Schnarchlautstärke genutzt werden. Weitere Modifikationen sind erforderlich, um die Genauigkeit des Systems noch zu verbessern.Supported by: teilweise unterstützt durch IFU GmbH, Lichtena
External validation and recalibration of an incidental meningioma prognostic model - IMPACT: protocol for an international multicentre retrospective cohort study
Introduction: Due to the increased use of CT and MRI, the prevalence of incidental findings on brain scans is increasing. Meningioma, the most common primary brain tumour, is a frequently encountered incidental finding, with an estimated prevalence of 3/1000. The management of incidental meningioma varies widely with active clinical-radiological monitoring being the most accepted method by clinicians. Duration of monitoring and time intervals for assessment, however, are not well defined. To this end, we have recently developed a statistical model of progression risk based on single-centre retrospective data. The model Incidental Meningioma: Prognostic Analysis Using Patient Comorbidity and MRI Tests (IMPACT) employs baseline clinical and imaging features to categorise the patient with an incidental meningioma into one of three risk groups: low, medium and high risk with a proposed active monitoring strategy based on the risk and temporal trajectory of progression, accounting for actuarial life expectancy. The primary aim of this study is to assess the external validity of this model. Methods and analysis: IMPACT is a retrospective multicentre study which will aim to include 1500 patients with an incidental intracranial meningioma, powered to detect a 10% progression risk. Adult patients ≥16 years diagnosed with an incidental meningioma between 1 January 2009 and 31 December 2010 will be included. Clinical and radiological data will be collected longitudinally until the patient reaches one of the study endpoints: intervention (surgery, stereotactic radiosurgery or fractionated radiotherapy), mortality or last date of follow-up. Data will be uploaded to an online Research Electronic Data Capture database with no unique identifiers. External validity of IMPACT will be tested using established statistical methods. Ethics and dissemination: Local institutional approval at each participating centre will be required. Results of the study will be reported through peer-reviewed articles and conferences and disseminated to participating centres, patients and the public using social media