635 research outputs found
Radial Velocity Studies of Close Binary Stars. IX
Radial-velocity measurements and sine-curve fits to the orbital velocity
variations are presented for the eighth set of ten close binary systems: AB
And, V402 Aur, V445 Cep, V2082 Cyg, BX Dra, V918 Her, V502 Oph, V1363 Ori, KP
Peg, V335 Peg. Half of the systems (V445 Cep, V2082 Cyg, V918 Her, V1363 Ori,
V335 Peg) were discovered photometrically by the Hipparcos mission and all
systems are double-lined (SB2) contact binaries. The broadening function method
permitted improvement of the orbital elements for AB And and V502 Oph. The
other systems have been observed for radial velocity variations for the first
time; in this group are five bright (V<7.5) binaries: V445 Cep, V2082 Cyg, V918
Her, KP Peg and V335 Peg. Several of the studied systems are prime candidates
for combined light and radial-velocity synthesis solutions.Comment: 17+ pages, 2 tables, 4 figure
How well do physical activity questions perform? A European cognitive testing study
<p><b>BACKGROUND: </b>Only few studies have focused on the cognitive processes of the respondents that are involved when answering physical activity questionnaires (PAQs). This study aimed at examining whether two PAQs work as intended with different segments of the survey population in different cultural settings in Europe.</p><p><b>METHODS: </b>The International Physical Activity Questionnaire - Short Form (IPAQ-SF) and the US National Health Interview Survey - Adult Core Physical Activity Questionnaire (NHIS-PAQ) were tested in Belgium, Estonia, Germany and the UK using a standardized cognitive interviewing procedure. IPAQ-SF measures total vigorous physical activity (PA), moderate PA, walking and sitting. NHIS-PAQ measures leisure-time vigorous PA, light and moderate PA and muscle-strengthening PA. In total 62 persons completed cognitive interviews, at least 15 interviews were conducted in each country.</p><p><b>RESULTS: </b>Both PAQs performed as intended with young and high-skilled persons and those having a regular exercise schedule. For the others, however, the testing revealed that problems occurred with both PAQs relating to understanding the concepts of '(light and) moderate' and 'vigorous' PA, classifying activities into the provided answer options of different PA intensities, recalling instances of 'normal' activities such as walking and sitting, and calculating the total duration of more than one activity or instance of an activity. The revealed problems with the questionnaires were quite similar in different countries; profound cultural differences were not observed.</p><p><b>CONCLUSIONS: </b>Both questionnaires were difficult to answer for many respondents and rather user-unfriendly. They are designed to measure an exactness of PA quantity (frequency and duration) and intensity which would be desirable to obtain from a scientific point of view; however, respondents can hardly provide this information for cognitive reasons. Studies investigating the respondents' perspective are useful for improving physical activity information based on self-reports.</p></p
The Palomar Testbed Interferometer Calibrator Catalog
The Palomar Testbed Interferometer (PTI) archive of observations between 1998
and 2005 is examined for objects appropriate for calibration of optical
long-baseline interferometer observations - stars that are predictably
point-like and single. Approximately 1,400 nights of data on 1,800 objects were
examined for this investigation. We compare those observations to an
intensively studied object that is a suitable calibrator, HD217014, and
statistically compare each candidate calibrator to that object by computing
both a Mahalanobis distance and a Principal Component Analysis. Our hypothesis
is that the frequency distribution of visibility data associated with
calibrator stars differs from non-calibrator stars such as binary stars.
Spectroscopic binaries resolved by PTI, objects known to be unsuitable for
calibrator use, are similarly tested to establish detection limits of this
approach. From this investigation, we find more than 350 observed stars
suitable for use as calibrators (with an additional being
rejected), corresponding to sky coverage for PTI. This approach
is noteworthy in that it rigorously establishes calibration sources through a
traceable, empirical methodology, leveraging the predictions of spectral energy
distribution modeling but also verifying it with the rich body of PTI's on-sky
observations.Comment: 100 pages, 7 figures, 7 tables; to appear in the May 2008ApJS, v176n
The low level of debris disk activity at the time of the Late Heavy Bombardment: a Spitzer study of Praesepe
We present 24 micron photometry of the intermediate-age open cluster
Praesepe. We assemble a catalog of 193 probable cluster members that are
detected in optical databases, the Two Micron All Sky Survey (2MASS), and at 24
micron, within an area of ~ 2.47 square degrees. Mid-IR excesses indicating
debris disks are found for one early-type and for three solar-type stars.
Corrections for sampling statistics yield a 24 micron excess fraction (debris
disk fraction) of 6.5 +- 4.1% for luminous and 1.9 +- 1.2% for solar-type
stars. The incidence of excesses is in agreement with the decay trend of debris
disks as a function of age observed for other cluster and field stars. The
values also agree with those for older stars, indicating that debris generation
in the zones that emit at 24 micron falls to the older 1-10 Gyr field star
sample value by roughly 750 Myr.
We discuss our results in the context of previous observations of excess
fractions for early- and solar-type stars. We show that solar-type stars lose
their debris disk 24 micron excesses on a shorter timescale than early-type
stars. Simplistic Monte Carlo models suggest that, during the first Gyr of
their evolution, up to 15-30% of solar-type stars might undergo an orbital
realignment of giant planets such as the one thought to have led to the Late
Heavy Bombardment, if the length of the bombardment episode is similar to the
one thought to have happened in our Solar System.
In the Appendix, we determine the cluster's parameters via boostrap Monte
Carlo isochrone fitting, yielding an age of 757 Myr (+- 36 Myr at 1 sigma
confidence) and a distance of 179 pc (+- 2 pc at 1 sigma confidence), not
allowing for systematic errors.Comment: 22 pages, 14 figures, 9 tables, emulateapj format; Accepted for
publication in The Astrophysical Journa
Coach development through collaborative action research: enhancing the learning environment within a national talent development system
Motivation to learn is an essential factor of talent being realised , which throws into light the essential role that the motivational climate plays in developing talent. Through collaborative action research, the aim of this study was to develop coaches’ learning to enhance the learning environment within a national talent development system, utilising the) TARGET framework (task, authority, recognition, grouping, evaluation and time). Results revealed that participatory collaborative action research is an effective coach development tool for coaches in order to enhance their learning and the motivational climate within their sessions. The study identified the benefits of coach development through participatory action research, revealing a highly positive response to the role that collaborative learning played in pedagogical developmen
Complexity of multi-dimensional spontaneous EEG decreases during propofol induced general anaesthesia
Emerging neural theories of consciousness suggest a correlation between a specific type of neural dynamical complexity and the level of consciousness: When awake and aware, causal interactions between brain regions are both integrated (all regions are to a certain extent connected) and differentiated (there is inhomogeneity and variety in the interactions). In support of this, recent work by Casali et al (2013) has shown that Lempel-Ziv complexity correlates strongly with conscious level, when computed on the EEG response to transcranial magnetic stimulation. Here we investigated complexity of spontaneous high-density EEG data during propofol-induced general anaesthesia. We consider three distinct measures: (i) Lempel-Ziv complexity, which is derived from how compressible the data are; (ii) amplitude coalition entropy, which measures the variability in the constitution of the set of active channels; and (iii) the novel synchrony coalition entropy (SCE), which measures the variability in the constitution of the set of synchronous channels. After some simulations on Kuramoto oscillator models which demonstrate that these measures capture distinct ‘flavours’ of complexity, we show that there is a robustly measurable decrease in the complexity of spontaneous EEG during general anaesthesia
Calculating daily dose in the Observational Medical Outcomes Partnership Common Data Model
Purpose: We aimed to develop a standardized method to calculate daily dose (i.e., the amount of drug a patient was exposed to per day) of any drug on a global scale using only drug information of typical observational data in the Observational Medical Outcomes Partnership Common Data Model (OMOP CDM) and a single reference table from Observational Health Data Sciences And Informatics (OHDSI).
Materials and Methods: The OMOP DRUG_STRENGTH reference table contains information on the strength or concentration of drugs, whereas the OMOP DRUG_EXPOSURE table contains information on patients' drug prescriptions or dispensations/claims. Based on DRUG_EXPOSURE data from the primary care databases Clinical Practice Research Datalink GOLD (United Kingdom) and Integrated Primary Care Information (IPCI, The Netherlands) and healthcare claims from PharMetrics® Plus for Academics (USA), we developed four formulas to calculate daily dose given different DRUG_STRENGTH reference table information. We tested the dose formulas by comparing the calculated median daily dose to the World Health Organization (WHO) Defined Daily Dose (DDD) for six different ingredients in those three databases and additional four international databases representing a variety of healthcare settings: MAITT (Estonia, healthcare claims and discharge summaries), IQVIA Disease Analyzer Germany (outpatient data), IQVIA Longitudinal Patient Database Belgium (outpatient data), and IMASIS Parc Salut (Spain, hospital data). Finally, in each database, we assessed the proportion of drug records for which daily dose calculations were possible using the suggested formulas.
Results: Applying the dose formulas, we obtained median daily doses that generally matched the WHO DDD definitions. Our dose formulas were applicable to >85% of drug records in all but one of the assessed databases.
Conclusion: We have established and implemented a standardized daily dose calculation in OMOP CDM providing reliable and reproducible results
Phenomenology As Philosophy and Method
Phenomenology is a philosophical movement that approaches the study of human beings and their culture differently from the logical positivist model used in the natural sciences and in special education. phenomenologists view the application of the logical positivist model to the study of human beings as inappropriate because the model does not address the uniqueness of human life. in this article, the theroetical assumptions and methodological orientations of phenomenology are discussed, followed by their applications to ways of doing research in special education.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68638/2/10.1177_074193259501600305.pd
Soft-bound synaptic plasticity increases storage capacity
Accurate models of synaptic plasticity are essential to understand the adaptive properties of the nervous system and for realistic models of learning and memory. Experiments have shown that synaptic plasticity depends not only on pre- and post-synaptic activity patterns, but also on the strength of the connection itself. Namely, weaker synapses are more easily strengthened than already strong ones. This so called soft-bound plasticity automatically constrains the synaptic strengths. It is known that this has important consequences for the dynamics of plasticity and the synaptic weight distribution, but its impact on information storage is unknown. In this modeling study we introduce an information theoretic framework to analyse memory storage in an online learning setting. We show that soft-bound plasticity increases a variety of performance criteria by about 18% over hard-bound plasticity, and likely maximizes the storage capacity of synapses
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