63 research outputs found

    Empirically-Based Warehouse Design: Can Academics Accept Such an Approach?

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    It is our opinion that existing research is not sufficient to support the design of a warehouse. As a result, facility designers that work in practice are left to face the design process with their own methods. These methods are in stark contrast to the analytical models developed in academia in that they are highly based on empirical observations. Supported by a collection of empirical observations, facility designers who work in practice employ an ad hoc design process. We present a design process based on empirical observations and then formalize it so that it can be taught and used. We illustrate the process with an example and discuss ways in which analytical methods can be used to supplement the process and improve the design. We conclude by describing additional work that is required if the design process is to be realized

    All-sky search for continuous gravitational waves from isolated neutron stars using Advanced LIGO and Advanced Virgo O3 data

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    We present results of an all-sky search for continuous gravitational waves which can be produced by spinning neutron stars with an asymmetry around their rotation axis, using data from the third observing run of the Advanced LIGO and Advanced Virgo detectors. Four different analysis methods are used to search in a gravitational-wave frequency band from 10 to 2048 Hz and a first frequency derivative from −10−8-10^{-8} to 10−910^{-9} Hz/s. No statistically-significant periodic gravitational-wave signal is observed by any of the four searches. As a result, upper limits on the gravitational-wave strain amplitude h0h_0 are calculated. The best upper limits are obtained in the frequency range of 100 to 200 Hz and they are ∌1.1×10−25{\sim}1.1\times10^{-25} at 95\% confidence-level. The minimum upper limit of 1.10×10−251.10\times10^{-25} is achieved at a frequency 111.5 Hz. We also place constraints on the rates and abundances of nearby planetary- and asteroid-mass primordial black holes that could give rise to continuous gravitational-wave signals

    Search for continuous gravitational wave emission from the Milky Way center in O3 LIGO--Virgo data

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    We present a directed search for continuous gravitational wave (CW) signals emitted by spinning neutron stars located in the inner parsecs of the Galactic Center (GC). Compelling evidence for the presence of a numerous population of neutron stars has been reported in the literature, turning this region into a very interesting place to look for CWs. In this search, data from the full O3 LIGO--Virgo run in the detector frequency band [10,2000] Hz[10,2000]\rm~Hz have been used. No significant detection was found and 95%\% confidence level upper limits on the signal strain amplitude were computed, over the full search band, with the deepest limit of about 7.6×10−267.6\times 10^{-26} at ≃142 Hz\simeq 142\rm~Hz. These results are significantly more constraining than those reported in previous searches. We use these limits to put constraints on the fiducial neutron star ellipticity and r-mode amplitude. These limits can be also translated into constraints in the black hole mass -- boson mass plane for a hypothetical population of boson clouds around spinning black holes located in the GC.Comment: 25 pages, 5 figure

    First joint observation by the underground gravitational-wave detector KAGRA with GEO 600

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    We report the results of the first joint observation of the KAGRA detector with GEO 600. KAGRA is a cryogenic and underground gravitational-wave detector consisting of a laser interferometer with 3 km arms, located in Kamioka, Gifu, Japan. GEO 600 is a British-German laser interferometer with 600 m arms, located near Hannover, Germany. GEO 600 and KAGRA performed a joint observing run from April 7 to 20, 2020. We present the results of the joint analysis of the GEO-KAGRA data for transient gravitational-wave signals, including the coalescence of neutron-star binaries and generic unmodeled transients. We also perform dedicated searches for binary coalescence signals and generic transients associated with gamma-ray burst events observed during the joint run. No gravitational-wave events were identified. We evaluate the minimum detectable amplitude for various types of transient signals and the spacetime volume for which the network is sensitive to binary neutron-star coalescences. We also place lower limits on the distances to the gamma-ray bursts analyzed based on the non-detection of an associated gravitational-wave signal for several signal models, including binary coalescences. These analyses demonstrate the feasibility and utility of KAGRA as a member of the global gravitational-wave detector network

    All-sky search for continuous gravitational waves from isolated neutron stars using Advanced LIGO and Advanced Virgo O3 data

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    We present results of an all-sky search for continuous gravitational waves which can be produced by spinning neutron stars with an asymmetry around their rotation axis, using data from the third observing run of the Advanced LIGO and Advanced Virgo detectors. Four different analysis methods are used to search in a gravitational-wave frequency band from 10 to 2048 Hz and a first frequency derivative from −10−8-10^{-8} to 10−910^{-9} Hz/s. No statistically-significant periodic gravitational-wave signal is observed by any of the four searches. As a result, upper limits on the gravitational-wave strain amplitude h0h_0 are calculated. The best upper limits are obtained in the frequency range of 100 to 200 Hz and they are ∌1.1×10−25{\sim}1.1\times10^{-25} at 95\% confidence-level. The minimum upper limit of 1.10×10−251.10\times10^{-25} is achieved at a frequency 111.5 Hz. We also place constraints on the rates and abundances of nearby planetary- and asteroid-mass primordial black holes that could give rise to continuous gravitational-wave signals.Comment: 23 main text pages, 17 figure

    Third universal definition of myocardial infarction

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    "Myocardial infarction (MI) can be recognised by clinical features, including electrocardiographic (ECG) findings, elevated values of biochemical markers (biomarkers) of myocardial necrosis, and by imaging, or may be defined by pathology. It is a major cause of death and disability worldwide. MI may be the first manifestation of coronary artery disease (CAD) or it may occur, repeatedly, in patients with established disease. Information on MI rates can provide useful information regarding the burden of CAD within and across populations, especially if standardized data are collected in a manner that distinguishes between incident and recurrent events. From the epidemiological point of view, the incidence of MI in a population can be used as a proxy for the prevalence of CAD in that population. The term ‘myocardial infarction’ may have major psychological and legal implications for the individual and society. It is an indicator of one of the leading health problems in the world and it is an outcome measure in clinical trials, observational studies and quality assurance programmes. These studies and programmes require a precise and consistent definition of MI. In the past, a general consensus existed for the clinical syndrome designated as MI. In studies of disease prevalence, the World Health Organization (WHO) defined MI from symptoms, ECG abnormalities and cardiac enzymes. However, the development of ever more sensitive and myocardial tissue-specific cardiac biomarkers and more sensitive imaging techniques now allows for detection of very small amounts of myocardial injury or necrosis. Additionally, the management of patients with MI has significantly improved, resulting in less myocardial injury and necrosis, in spite of a similar clinical presentation. Moreover, it appears necessary to distinguish the various conditions which may cause MI, such as ‘spontaneous’ and ‘procedure-related’ MI. Accordingly, physicians, other healthcare providers and patients require an up-to-date definition of MI.

    Third universal definition of myocardial infarction

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    "Myocardial infarction (MI) can be recognised by clinical features, including electrocardiographic (ECG) findings, elevated values of biochemical markers (biomarkers) of myocardial necrosis, and by imaging, or may be defined by pathology. It is a major cause of death and disability worldwide. MI may be the first manifestation of coronary artery disease (CAD) or it may occur, repeatedly, in patients with established disease. Information on MI rates can provide useful information regarding the burden of CAD within and across populations, especially if standardized data are collected in a manner that distinguishes between incident and recurrent events. From the epidemiological point of view, the incidence of MI in a population can be used as a proxy for the prevalence of CAD in that population. The term ‘myocardial infarction’ may have major psychological and legal implications for the individual and society. It is an indicator of one of the leading health problems in the world and it is an outcome measure in clinical trials, observational studies and quality assurance programmes. These studies and programmes require a precise and consistent definition of MI. In the past, a general consensus existed for the clinical syndrome designated as MI. In studies of disease prevalence, the World Health Organization (WHO) defined MI from symptoms, ECG abnormalities and cardiac enzymes. However, the development of ever more sensitive and myocardial tissue-specific cardiac biomarkers and more sensitive imaging techniques now allows for detection of very small amounts of myocardial injury or necrosis. Additionally, the management of patients with MI has significantly improved, resulting in less myocardial injury and necrosis, in spite of a similar clinical presentation. Moreover, it appears necessary to distinguish the various conditions which may cause MI, such as ‘spontaneous’ and ‘procedure-related’ MI. Accordingly, physicians, other healthcare providers and patients require an up-to-date definition of MI.

    Search for subsolar-mass binaries in the first half of Advanced LIGO’s and Advanced Virgo’s third observing run

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    We report on a search for compact binary coalescences where at least one binary component has a mass between 0.2 M_\odot and 1.0 M_\odot in Advanced LIGO and Advanced Virgo data collected between 1 April 2019 1500 UTC and 1 October 2019 1500 UTC. We extend previous analyses in two main ways: we include data from the Virgo detector and we allow for more unequal mass systems, with mass ratio q \geq 0.1. We do not report any gravitational-wave candidates. The most significant trigger has a false alarm rate of 0.14 \mathrm{yr}^-1. This implies an upper limit on the merger rate of subsolar binaries in the range [220–24200] \mathrm{Gpc}^{-3} \, \mathrm{yr}^{-1}, depending on the chirp mass of the binary. We use this upper limit to derive astrophysical constraints on two phenomenological models that could produce subsolar-mass compact objects. One is an isotropic distribution of equal-mass primordial black holes. Using this model, we find that the fraction of dark matter in primordial black holes is f_\mathrm{PBH}\equiv \Omega_\mathrm{PBH}/\Omega_\mathrm{DM}\lesssim 6\%. The other is a dissipative dark matter model, in which fermionic dark matter can collapse and form black holes. The upper limit on the fraction of dark matter black holes depends on the minimum mass of the black holes that can be formed: the most constraining result is obtained at M_\mathrm{min}=1 M_\odot, where f_\mathrm{DBH}\equiv \Omega_\mathrm{PBH}/\Omega_\mathrm{DM}\lesssim 0.003\%. These are the tightest limits on spinning subsolar-mass binaries to date

    All-sky search for gravitational wave emission from scalar boson clouds around spinning black holes in LIGO O3 data

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    This paper describes the first all-sky search for long-duration, quasimonochromatic gravitational-wave signals emitted by ultralight scalar boson clouds around spinning black holes using data from the third observing run of Advanced LIGO. We analyze the frequency range from 20 to 610 Hz, over a small frequency derivative range around zero, and use multiple frequency resolutions to be robust towards possible signal frequency wanderings. Outliers from this search are followed up using two different methods, one more suitable for nearly monochromatic signals, and the other more robust towards frequency fluctuations. We do not find any evidence for such signals and set upper limits on the signal strain amplitude, the most stringent being ≈10−25 at around 130 Hz. We interpret these upper limits as both an “exclusion region” in the boson mass/black hole mass plane and the maximum detectable distance for a given boson mass, based on an assumption of the age of the black hole/boson cloud system
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