886 research outputs found
Children's Health Status: Examining the Associations among Income Poverty, Material Hardship, and Parental Factors
BACKGROUND: We examined a model of multiple mediating pathways of income poverty, material hardship, parenting factors, and child health status to understand how material hardship and parental factors mediate the effects of poverty on child health. We hypothesized that: (a) poverty will be directly associated with material hardship, parental depression, and health status, and indirectly with parenting behaviors through its effects on parental depression and material hardship; (b) material hardship will be associated with parental depression, parenting behaviors, and health status; and (c) parental depression will be correlated with parenting behaviors, and that both parental depression and parenting behaviors will predict child health. METHODS AND RESULTS: We used data from the 2002 National Survey of American Families for a sample of 9,645 6-to-11 year-olds to examine a 4-step structural equation model. The baseline model included covariates and income poverty. In the hardship model, food insufficiency and medical need were added to the baseline model. The parental model included parental depression and parenting behavior and baseline model. In the full model, all the constructs were included. First, income poverty had a direct effect on health status, and an indirect effect through its association with material hardship, parental depressive affect, and parenting behaviors. Medical need and food insufficiency had negative effects on child health, and indirect effects on health through their association with parental depression and parenting behaviors. Finally, parental depression and parenting behaviors were associated with child health, and part of the effect of parental depression on health was explained by its association with parenting behaviors. CONCLUSIONS: Poverty has an independent effect on health, however, its effects are partially explained by material hardship, parental depression and parental behaviors. To improve children's health would require a multi-pronged approach involving income transfers, health insurance coverage, food and nutrition assistance, and parenting interventions
Household Food Insecurity Predictive of Health Status in Early Adolescence? A Structural Analysis Using the 2002 NSAF Data Set
We used data from the 2002 National Survey of American Families to examine a structural model of the relations among food insecurity, poor nutritional status, parental mental health problems, quality of parenting, adolescents’ emotional distress, and poor health status for a national sample of 5366 12-to-14 year-olds. The results revealed that: first, food insecurity was associated with elevated levels of parental mental health problems, diminished quality of parenting, elevated levels of adolescents’ emotional problems, and higher incidence of poor nutritional and health statuses. Second, parental mental health problems were associated with diminished quality of parenting and higher incidence of poor health status; and quality of parenting had a negative effect on emotional distress, but not on health status. Finally, poor nutritional status was associated with elevated levels of emotional distress and higher incidence of poor health status; and emotional distress was predictive of poor health status. The findings of this study highlight the mediating role of nutritional status, parenting factors and adolescents’ emotional well-being in the link between food insecurity and health; and point to the complex interaction between food insecurity and health status
A Computer Analysis of Energy Use and Energy Conservation Options for a Twelve Story Office Building in Austin, Texas
The energy use of the Travis Building
at Austin, Texas was analyzed using the DOE
2.1B building energy simulation program.
An analysis was made for the building as
specified in the building plans and as
operated by the personnel currently
occupying the building. The energy
consumption of the building was compared
with the energy consumption of the building
modified to comply with the proposed ASHRAE
90.1p standards. The base design and the
ASHRAE design of the Travis building were
evaluated in Brownsville, Houston, Lubbock,
and El Paso to study the influence of the
weather on its energy consumption. In
addition, a glass with high reflectivity
and low overall heat transfer coefficient
was used to study the reduction of glass
conduction and glass solar loads. Finally,
the energy consumption of the modified
building was compared with the energy
consumption of the modified building which
conformed to the California energy
standards
A 43-Gbps Lithium Niobate Modulator Driver Module
This paper describes the realization of a 43-Gbps Lithium Niobate modulator driver module. The NRZ driver module utilizes four stages of GaAs p-HEMT MMIC amplifiers integrated with an output level detector and feedback loop to provide thermal stability and external control of the output swing. The bias and loop control circuitry are contained in the housing on a PC board external to the sealed MIC section. The integrated module (50.8 x 73.4 x 9.5 mm 3) provides 6.0 Vp-p controllable single-ended output voltage while dissipating only 4 watt
Detecting Planets Around Very Low Mass Stars with the Radial Velocity Method
The detection of planets around very low-mass stars with the radial velocity
method is hampered by the fact that these stars are very faint at optical
wavelengths where the most high-precision spectrometers operate. We investigate
the precision that can be achieved in radial velocity measurements of low mass
stars in the near infrared (nIR) Y-, J-, and H-bands, and we compare it to the
precision achievable in the optical. For early-M stars, radial velocity
measurements in the nIR offer no or only marginal advantage in comparison to
optical measurements. Although they emit more flux in the nIR, the richness of
spectral features in the optical outweighs the flux difference. We find that
nIR measurement can be as precise than optical measurements in stars of
spectral type ~M4, and from there the nIR gains in precision towards cooler
objects. We studied potential calibration strategies in the nIR finding that a
stable spectrograph with a ThAr calibration can offer enough wavelength
stability for m/s precision. Furthermore, we simulate the wavelength-dependent
influence of activity (cool spots) on radial velocity measurements from optical
to nIR wavelengths. Our spot simulations reveal that the radial velocity jitter
does not decrease as dramatically towards longer wavelengths as often thought.
The jitter strongly depends on the details of the spots, i.e., on spot
temperature and the spectral appearance of the spot. Forthcoming nIR
spectrographs will allow the search for planets with a particular advantage in
mid- and late-M stars. Activity will remain an issue, but simultaneous
observations at optical and nIR wavelengths can provide strong constraints on
spot properties in active stars.Comment: accepted by ApJ, v2 accepted revision with new precision
calculations, abstract abride
Disinfection of Spacecraft Potable Water Systems by Photocatalytic Oxidation Using UV-A Light Emitting Diodes
Ultraviolet (UV) light has long been used in terrestrial water treatment systems for photodisinfection and the removal of organic compounds by several processes including photoadsorption, photolysis, and photocatalytic oxidation/reduction. Despite its effectiveness for water treatment, UV has not been explored for spacecraft applications because of concerns about the safety and reliability of mercury-containing UV lamps. However, recent advances in ultraviolet light emitting diodes (UV LEDs) have enabled the utilization of nanomaterials that possess the appropriate optical properties for the manufacture of LEDs capable of producing monochromatic light at germicidal wavelengths. This report describes the testing of a commercial-off-the-shelf, high power Nichia UV-A LED (250mW A365nnJ for the excitation of titanium dioxide as a point-of-use (POD) disinfection device in a potable water system. The combination of an immobilized, high surface area photocatalyst with a UV-A LED is promising for potable water system disinfection since toxic chemicals and resupply requirements are reduced. No additional consumables like chemical biocides, absorption columns, or filters are required to disinfect and/or remove potentially toxic disinfectants from the potable water prior to use. Experiments were conducted in a static test stand consisting of a polypropylene microtiter plate containing 3mm glass balls coated with titanium dioxide. Wells filled with water were exposed to ultraviolet light from an actively-cooled UV-A LED positioned above each well and inoculated with six individual challenge microorganisms recovered from the International Space Station (ISS): Burkholderia cepacia, Cupriavidus metallidurans, Methylobacterium fujisawaense, Pseudomonas aeruginosa, Sphingomonas paucimobilis and Wautersia basilensis. Exposure to the Nichia UV-A LED with photocatalytic oxidation resulted in a complete (>7-log) reduction of each challenge bacteria population in <180 minutes of contact time. With continued advances in the design and manufacture of UV-A LEDs and semi-conducting photocatalysts, LED activated photochemical process technology promises to extend its application to spacecraft environmental systems
Development of Temperature and Humidity-Based Indicators for Diagnosing Problems in Low Tonnage, Split System Air Conditioners
This paper presents results of a survey of the
literature and identifies the most common degraded
conditions associated with low-tonnage air
conditioners. Other laboratory studies as well as
marketed diagnostic systems are also summarized. A
procedure for identification of useful, low-cost
temperature-based indicators of degraded conditions
has been developed at the Energy Systems
Laboratory, Texas A&M University in College
Station, TX under contract to Honeywell. This paper
presents the methodology used to identify the
temperature-based indicators for the most common
degraded conditions gleaned from the literature
The Impact of Endothall on the Aquatic Plant Community of Kress Lake, Washington
CA dense mat-forming population of Eurasian watermilfoil
(
Myriophyllum spicatum
L
.
) was interfering with fishing and
recreation in a small western Washington lake. A low concentration
(1.5 mg/L active ingredient) of the herbicide endothall
formulated as Aquathol® K was used in 2000 to attempt
to selectively control the Eurasian watermilfoil. Aquatic plant
biomass and frequency data were collected before treatment,
ten weeks after treatment and during the growing season for
3 additional years. Macrophyte data were analyzed to assess
the herbicide’s impacts on Eurasian watermilfoil as well as
the rest of the aquatic plant community. Results showed a significant
decrease in Eurasian watermilfoil biomass and frequency
10 weeks after treatment. The Eurasian watermilfoil
continued to be present, but at a significantly reduced level
through the remainder of the study (3 years after treatment).
Of the native plant species, large-leaf pondweed (
Potamogeton
amplifolius
Tucker
.
) frequency and biomass was significantly
reduced after treatment. Common elodea (
Elodea canadensis
Rich.), muskgrass (
Chara
sp. Vallaint.) and bladderwort (
Utricularia
sp. L.) all increased significantly after treatment.
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