110 research outputs found
Smart exercise application to improve leg function and short-term memory through game- like lunge exercises: development and evaluation
The purpose of this study was to evaluate the functionality, accuracy, and usability of a novel smart exercise application (SEA). The functionality such as counting lunges, providing task-related auditory feedback, and testing short-term memory was examined while thirteen young adults (six men, age 25.4 ± 8.3 years) performed the lunge exercise with the SEA. The accuracy of logged motion data including angles and accelerations were also tested. Another twenty-five participants (11 men, age 23.2 ± 5.7 years) evaluated the usability of the SEA interest, motivation, convenience, and strength/cognitive benefit via a questionnaire. The SEA assessed the lunge motion correctly, provided auditory feedback, and tested users’ short-term memory as required. High correlations (r = 0.90 to 0.99) with low RMSE (4.85 ̊ for direction angle, 0.13 to 0.22 m/ s2 for acceleration) were observed between the sensor output and the reference output. Bland-Altman plot also showed a low discrepancy between each of the two measures. Most participants positively answered all questions about interest (60%), motivation (40%), convenience (80%), strength benefits (92%), and cognitive benefits (88%) of the SEA. The SEA demonstrated accurate kinematic assessment of accelerations and directions, assessed the lunge motion correctly, and created the appropriate auditory feedback on the short- term memory task. The high rate of positive responses suggested the potential of the application in future use
Curved Space or Curved Vacuum?
While the simple picture of a spatially flat, matter plus cosmological
constant universe fits current observation of the accelerated expansion, strong
consideration has also been given to models with dynamical vacuum energy. We
examine the tradeoff of ``curving'' the vacuum but retaining spatial flatness,
vs. curving space but retaining the cosmological constant. These different
breakdowns in the simple picture could readily be distinguished by combined
high accuracy supernovae and cosmic microwave background distance measurements.
If we allow the uneasy situation of both breakdowns, the curvature can still be
measured to 1%, but at the price of degrading estimation of the equation of
state time variation by 60% or more, unless additional information (such as
weak lensing data or a tight matter density prior) is included.Comment: 7 pages, 6 figures; minor changes to match version accepted to
Astroparticle Physics and correct typo at bottom of page
Improving the LSST dithering pattern and cadence for dark energy studies
The Large Synoptic Survey Telescope (LSST) will explore the entire southern
sky over 10 years starting in 2022 with unprecedented depth and time sampling
in six filters, . Artificial power on the scale of the 3.5 deg LSST
field-of-view will contaminate measurements of baryonic acoustic oscillations
(BAO), which fall at the same angular scale at redshift . Using the
HEALPix framework, we demonstrate the impact of an "un-dithered" survey, in
which of each LSST field-of-view is overlapped by neighboring
observations, generating a honeycomb pattern of strongly varying survey depth
and significant artificial power on BAO angular scales. We find that adopting
large dithers (i.e., telescope pointing offsets) of amplitude close to the LSST
field-of-view radius reduces artificial structure in the galaxy distribution by
a factor of 10. We propose an observing strategy utilizing large dithers
within the main survey and minimal dithers for the LSST Deep Drilling Fields.
We show that applying various magnitude cutoffs can further increase survey
uniformity. We find that a magnitude cut of removes significant
spurious power from the angular power spectrum with a minimal reduction in the
total number of observed galaxies over the ten-year LSST run. We also determine
the effectiveness of the observing strategy for Type Ia SNe and predict that
the main survey will contribute 100,000 Type Ia SNe. We propose a
concentrated survey where LSST observes one-third of its main survey area each
year, increasing the number of main survey Type Ia SNe by a factor of
1.5, while still enabling the successful pursuit of other science
drivers.Comment: 9 pages, 6 figures, published in SPIE proceedings; corrected typo in
equation
Design of Single-modal Take-over Request in SAE Level 2 & 3 Automated Vehicle
Recently, cutting-edge technology has led to the development of automated vehicles, but the limitations of the related technology may lead to hazardous situations. This resulted in the remarkable significance of the interaction between automated vehicles and drivers. In particular, the transition between the driver and the automated vehicle in accordance with Level 3 of SAE J3016 is inevitable, and guidelines or standards regarding the takeover should be provided. Therefore, we aim to prepare the safety guidelines for the takeover and to conduct a comparative test. First, guidelines for visual, auditory, and haptic displays in existing vehicles were examined. Second, preliminary research was conducted on the modality of automated vehicles. Third, we carried out a modality investigation regarding the partially automated vehicle. Based on this, we proposed visual, auditory, and haptic signals for each modality. This will serve as a significant starting point for future research based on multimodal methods
Chandra Observations of Type Ia Supernovae: Upper Limits to the X-ray Flux of SN 2002bo, SN 2002ic, SN 2005gj, and SN 2005ke
We set sensitive upper limits to the X-ray emission of four Type Ia
supernovae (SNe Ia) using the Chandra X-ray Observatory. SN 2002bo, a normal,
although reddened, nearby SN Ia, was observed 9.3 days after explosion. For an
absorbed, high temperature bremsstrahlung model the flux limits are 3.2E-16
ergs/cm^2/s (0.5-2 keV band) and 4.1E-15 ergs/cm^2/s (2-10 keV band). Using
conservative model assumptions and a 10 km/s wind speed, we derive a mass loss
rate of \dot{M} ~ 2E-5 M_\odot/yr, which is comparable to limits set by the
non-detection of Halpha lines from other SNe Ia. Two other objects, SN 2002ic
and SN 2005gj, observed 260 and 80 days after explosion, respectively, are the
only SNe Ia showing evidence for circumstellar interaction. The SN 2002ic X-ray
flux upper limits are ~4 times below predictions of the interaction model
currently favored to explain the bright optical emission. To resolve this
discrepancy we invoke the mixing of cool dense ejecta fragments into the
forward shock region, which produces increased X-ray absorption. A modest
amount of mixing allows us to accommodate the Chandra upper limit. SN 2005gj is
less well studied at this time. Assuming the same circumstellar environment as
for SN 2002i, the X-ray flux upper limits for SN 2005gj are ~4 times below the
predictions, suggesting that mixing of cool ejecta into the forward shock has
also occurred here. Our reanalysis of Swift and Chandra data on SN 2005ke does
not confirm a previously reported X-ray detection. The host galaxies NGC 3190
(SN 2002bo) and NGC 1371 (SN 2005ke) each harbor a low luminosity (L_X ~ 3-4E40
ergs/s) active nucleus in addition to wide-spread diffuse soft X-ray emission.Comment: 16 pages, to appear in ApJ (20 Nov 2007
The Carnegie Supernova Project: First Near-Infrared Hubble Diagram to z~0.7
The Carnegie Supernova Project (CSP) is designed to measure the luminosity
distance for Type Ia supernovae (SNe Ia) as a function of redshift, and to set
observational constraints on the dark energy contribution to the total energy
content of the Universe. The CSP differs from other projects to date in its
goal of providing an I-band {rest-frame} Hubble diagram. Here we present the
first results from near-infrared (NIR) observations obtained using the Magellan
Baade telescope for SNe Ia with 0.1 < z < 0.7. We combine these results with
those from the low-redshift CSP at z <0.1 (Folatelli et al. 2009). We present
light curves and an I-band Hubble diagram for this first sample of 35 SNe Ia
and we compare these data to 21 new SNe Ia at low redshift. These data support
the conclusion that the expansion of the Universe is accelerating. When
combined with independent results from baryon acoustic oscillations (Eisenstein
et al. 2005), these data yield Omega_m = 0.27 +/- 0.0 (statistical), and
Omega_DE = 0.76 +/- 0.13 (statistical) +/- 0.09 (systematic), for the matter
and dark energy densities, respectively. If we parameterize the data in terms
of an equation of state, w, assume a flat geometry, and combine with baryon
acoustic oscillations, we find that w = -1.05 +/- 0.13 (statistical) +/- 0.09
(systematic). The largest source of systematic uncertainty on w arises from
uncertainties in the photometric calibration, signaling the importance of
securing more accurate photometric calibrations for future supernova cosmology
programs. Finally, we conclude that either the dust affecting the luminosities
of SNe Ia has a different extinction law (R_V = 1.8) than that in the Milky Way
(where R_V = 3.1), or that there is an additional intrinsic color term with
luminosity for SNe Ia independent of the decline rate.Comment: 44 pages, 23 figures, 9 tables; Accepted for publication in the
Astrophysical Journa
Very Low Mass Stellar and Substellar Companions to Solar-Like Stars From MARVELS V: A Low Eccentricity Brown Dwarf from the Driest Part of the Desert, MARVELS-6b
We describe the discovery of a likely brown dwarf (BD) companion with a
minimum mass of 31.7 +/- 2.0 M_Jup to GSC 03546-01452 from the MARVELS radial
velocity survey, which we designate as MARVELS-6b. For reasonable priors, our
analysis gives a probability of 72% that MARVELS-6b has a mass below the
hydrogen-burning limit of 0.072 M_Sun, and thus it is a high-confidence BD
companion. It has a moderately long orbital period of 47.8929 +0.0063/-0.0062
days with a low eccentricty of 0.1442 +0.0078/-0.0073, and a semi-amplitude of
1644 +12/-13 m/s. Moderate resolution spectroscopy of the host star has
determined the following parameters: T_eff = 5598 +/- 63, log g = 4.44 +/-
0.17, and [Fe/H] = +0.40 +/- 0.09. Based upon these measurements, GSC
03546-01452 has a probable mass and radius of M_star = 1.11 +/- 0.11 M_Sun and
R_star = 1.06 +/- 0.23 R_Sun with an age consistent with less than ~6 Gyr at a
distance of 219 +/- 21 pc from the Sun. Although MARVELS-6b is not observed to
transit, we cannot definitively rule out a transiting configuration based on
our observations. There is a visual companion detected with Lucky Imaging at
7.7 arcsec from the host star, but our analysis shows that it is not bound to
this system. The minimum mass of MARVELS-6b exists at the minimum of the mass
functions for both stars and planets, making this a rare object even compared
to other BDs.Comment: 15 pages, 15 figures, 5 tables. Accepted for publication in The
Astronomical Journa
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