3,298 research outputs found
Video signal processing system uses gated current mode switches to perform high speed multiplication and digital-to-analog conversion
Video signal processor uses special-purpose integrated circuits with nonsaturating current mode switching to accept texture and color information from a digital computer in a visual spaceflight simulator and to combine these, for display on color CRT with analog information concerning fading
Customer Satisfaction Among Cable TV Subscribers: A Case Study of TCI of Illinois, Inc.
This study gauges customer satisfaction among subscribers of TCI of Illinois, Inc., cable company. Two research questions were formulated in order to determine the customer satisfaction levels: Can a satisfaction instrument be generated to measure customer satisfaction among cable subscribers? and What are the levels of customer satisfaction among TCI of Illinois, Inc., subscribers? Data was obtained from personal, mail and telephone surveying of a 10% random sample of Charleston cable television subscribers. The results indicate that a reliable and valid measuring device was generated and 39.5% of the respondents were satisfied with TCI overall
Brazilian Surface and Upper-level Wind Characteristics Based on Ground and Model Observations from 1980–2014
The examination of temporal changes in surface winds has been analyzed by scientists for a variety of physical, biological, climatological, and socioeconomic reasons. This research uses surface and upper-level wind data from historical in-situ and climate models to examine the geographical and climatological characteristics of wind across Brazil during 1980–2014. Overall linear and quantile regression shows that surface wind speed trends are changing regionally across Brazil. Wind speeds across northeastern Brazil are increasing, while a decreasing trend is documented for interior and southeastern Brazil. The spatial and temporal trends found are possibly related to alterations in the physical landscape (urbanization and land-cover change) and the seasonal relationship between the Intertropical Convergence Zone and the South Atlantic Anticyclone. To further examine the role of the South Atlantic Anticyclone, an additional analysis was performed to show how the position of high pressure system affects surface conditions across Brazil. Results show that surface winds across northern Brazil are affected by an equatorward shift of the semi-permanent high pressure, while southern Brazil is more influenced by migrating anticyclones that were passing through the South Atlantic Basin. A spatial and temporal analysis of upper-level wind speed trends was conducted to examine how surface and marco-scale features have evolved over Brazil. An overall vertical profile shows a decreasing trend in lower-level winds (1000–850 hPa) that switches to a positive trend in the upper portions of the atmosphere (400–200 hPa). A geographical interpretation of upper-level wind trends was performed based on a three-dimensional model. The model depicts that seasonal wind trend patterns across Brazil occur within the proximity of the Bolivian high and subtropical jet (400–200 hPa). A regional analysis confirms the role of these two synoptic features
Customer Satisfaction Among Cable TV Subscribers: A Case Study of TCI of Illinois, Inc.
This study gauges customer satisfaction among subscribers of TCI of Illinois, Inc., cable company. Two research questions were formulated in order to determine the customer satisfaction levels: Can a satisfaction instrument be generated to measure customer satisfaction among cable subscribers? and What are the levels of customer satisfaction among TCI of Illinois, Inc., subscribers? Data was obtained from personal, mail and telephone surveying of a 10% random sample of Charleston cable television subscribers. The results indicate that a reliable and valid measuring device was generated and 39.5% of the respondents were satisfied with TCI overall
Revision of Earth-sized Kepler Planet Candidate Properties with High Resolution Imaging by Hubble Space Telescope
We present the results of our Hubble Space Telescope program and describe how
our analysis methods were used to re-evaluate the habitability of some of the
most interesting Kepler planet candidates. Our program observed 22 Kepler
Object of Interest (KOI) host stars, several of which were found to be multiple
star systems unresolved by Kepler. We use our high-resolution imaging to
spatially resolve the stellar multiplicity of Kepler-296, KOI-2626, and
KOI-3049, and develop a conversion to the Kepler photometry (Kp) from the F555W
and F775W filters on WFC3/UVIS. The binary system Kepler-296 (5 planets) has a
projected separation of 0.217" (80AU); KOI-2626 (1 planet candidate) is a
triple star system with a projected separation of 0.201" (70AU) between the
primary and secondary components and 0.161" (55AU) between the primary and
tertiary; and the binary system KOI-3049 (1 planet candidate) has a projected
separation of 0.464" (225AU). We use our measured photometry to fit the
separated stellar components to the latest Victoria-Regina Stellar Models with
synthetic photometry to conclude that the systems are coeval. The components of
the three systems range from mid-K dwarf to mid-M dwarf spectral types. We
solved for the planetary properties of each system analytically and via an MCMC
algorithm using our independent stellar parameters. The planets range from
~1.6R_Earth to ~4.2R_Earth, mostly Super Earths and mini-Neptunes. As a result
of the stellar multiplicity, some planets previously in the Habitable Zone are,
in fact, not, and other planets may be habitable depending on their assumed
stellar host.Comment: 16 pages, 10 figures, ApJ, 804, 9
Kepler Mission Stellar and Instrument Noise Properties Revisited
An earlier study of the Kepler Mission noise properties on time scales of
primary relevance to detection of exoplanet transits found that higher than
expected noise followed to a large extent from the stars, rather than
instrument or data analysis performance. The earlier study over the first six
quarters of Kepler data is extended to the full four years ultimately
comprising the mission. Efforts to improve the pipeline data analysis have been
successful in reducing noise levels modestly as evidenced by smaller values
derived from the current data products. The new analyses of noise properties on
transit time scales show significant changes in the component attributed to
instrument and data analysis, with essentially no change in the inferred
stellar noise. We also extend the analyses to time scales of several days,
instead of several hours to better sample stellar noise that follows from
magnetic activity. On the longer time scale there is a shift in stellar noise
for solar-type stars to smaller values in comparison to solar values.Comment: 10 pages, 8 figures, accepted by A
The Formation Rate of Blue Stragglers in 47 Tucanae
We investigate the effects of changes in the blue straggler formation rate in
globular clusters on the blue straggler distribution in the color-magnitude
diagram. We find that the blue straggler distribution is highly sensitive to
the past formation rate. Comparing our models to new UBV observations of a
region close to the core of 47 Tucanae suggests that this cluster may have
stopped forming blue straggler formation several Gyr ago. This cessation of
formation can be associated with an epoch of primordial binary burning which
has been invoked in other clusters to infer the imminence of core collapse.Comment: 17 pages, 9 figures, submitted to the Astrophysical Journa
Parental stress increases body mass index trajectory in pre-adolescents.
What is already known about this subjectRates of childhood obesity have increased since the mid-1970s. Research into behavioural determinants has focused on physical inactivity and unhealthy diets. Cross-sectional studies indicate an association between psychological stress experienced by parents and obesity in pre-adolescents.What this study addsWe provide evidence of a prospective association between parental psychological stress and increased weight gain in pre-adolescents. Family-level support for those experiencing chronic stress might help promote healthy diet and exercise behaviours in children.ObjectiveWe examined the impact of parental psychological stress on body mass index (BMI) in pre-adolescent children over 4 years of follow-up.MethodsWe included 4078 children aged 5-10 years (90% were between 5.5 and 7.5 years) at study entry (2002-2003) in the Children's Health Study, a prospective cohort study in southern California. A multi-level linear model simultaneously examined the effect of parental stress at study entry on the attained BMI at age 10 and the slope of change across annual measures of BMI during follow-up, controlled for the child's age and sex. BMI was calculated based on objective measurements of height and weight by trained technicians following a standardized procedure.ResultsA two standard deviation increase in parental stress at study entry was associated with an increase in predicted BMI attained by age 10 of 0.287 kg m(-2) (95% confidence interval 0.016-0.558; a 2% increase at this age for a participant of average attained BMI). The same increase in parental stress was also associated with an increased trajectory of weight gain over follow-up, with the slope of change in BMI increased by 0.054 kg m(-2) (95% confidence interval 0.007-0.100; a 7% increase in the slope of change for a participant of average BMI trajectory).ConclusionsWe prospectively demonstrated a small effect of parental stress on BMI at age 10 and weight gain earlier in life than reported previously. Interventions to address the burden of childhood obesity should address the role of parental stress in children
Resolving the Controversy Over the Core Radius of 47 Tucanae (NGC 104)
This paper investigates the discrepancy between recent measurements of the
density profile of the globular cluster 47 Tuc that have used HST data sets.
Guhathakurta et al. (1992) used pre-refurbishment WFPC1 V-band images to derive
r_c = 23" +/- 2". Calzetti et al. (1993) suggested that the density profile is
a superposition of two King profiles (r_c = 8" and r_c = 25") based on U-band
FOC images. De Marchi et al. (1996) used deep WFPC1 U-band images to derive r_c
= 12" +/- 2". Differences in the adopted cluster centers are not the cause of
the discrepancy. Our independent analysis of the data used by De Marchi et al.
reaches the following conclusions: (1) De Marchi et al.'s r_c ~ 12" value is
spuriously low, a result of radially-varying bias in the star counts in a
magnitude limited sample -- photometric errors and a steeply rising stellar
luminosity function cause more stars to scatter across the limiting magnitude
into the sample than out of it, especially near the cluster center where
crowding effects are most severe. (2) Changing the limiting magnitude to the
main sequence turnoff, away from the steep part of the luminosity function,
partially alleviates the problem and results in r_c = 18". (3) Combining such a
limiting magnitude with accurate photometry derived from PSF fitting, instead
of the less accurate aperture photometry employed by De Marchi et al., results
in a reliable measurement of the density profile which is well fit by r_c = 22"
+/- 2". Archival WFPC2 data are used to derive a star list with a higher degree
of completeness, greater photometric accuracy, and wider areal coverage than
the WFPC1 and FOC data sets; the WFPC2-based density profile supports the above
conclusions, yielding r_c = 24" +/- 1.9".Comment: 22 pages, 5 figures, 1 table; accepted for publication in PASP; see
http://www.ucolick.org/~raja/hgg.tar.gz for full-resolution figure
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