79 research outputs found
Health Beliefs and Parenting Attitudes Influence Breastfeeding Patterns Among Low-income African-American women
OBJECTIVE: To describe breastfeeding initiation among 210 urban African-American mothers with inadequate prenatal care.
METHODS: This study is a caseâcontrol study of postpartum mothers recruited from four large urban hospitals.
RESULTS: Mothers who chose to breastfeed were more educated, employed before birth, married, and using contraception postnatally. Regression model analysis controlling for demographic differences revealed that breastfeeding was significantly associated with a higher perception of severity of illness and higher confidence in the ability of health care to prevent illness. Breastfeeding mothers were less likely to reverse parentâ child roles and had a lower perception of hassle from their infantâs behavior. When comparing mothers who breastfed longer than 8 weeks to those who did not breastfeed, breastfeeding mothers had high scores related to empathy toward infants on the AdultâAdolescent Parenting Inventory as well as a low perception of hassle on the Parenting Daily Hassle. The perception of existing formal or informal social support did not influence breastfeeding behavior.
CONCLUSION: Personal attributes of low-income urban mothers such as health beliefs and parental attitudes may play a role in the initiation and duration of breastfeeding. Low-income African-American mothers may be influenced in their choice to breastfeed by supportive messages from physicians and nurses delivering care to mothers and their newborns. Emphasis should be placed on the role breastfeeding can play in preventing childhood illnesses
Superprocesses as models for information dissemination in the Future Internet
Future Internet will be composed by a tremendous number of potentially
interconnected people and devices, offering a variety of services, applications
and communication opportunities. In particular, short-range wireless
communications, which are available on almost all portable devices, will enable
the formation of the largest cloud of interconnected, smart computing devices
mankind has ever dreamed about: the Proximate Internet. In this paper, we
consider superprocesses, more specifically super Brownian motion, as a suitable
mathematical model to analyse a basic problem of information dissemination
arising in the context of Proximate Internet. The proposed model provides a
promising analytical framework to both study theoretical properties related to
the information dissemination process and to devise efficient and reliable
simulation schemes for very large systems
The Taming of Closed Time-like Curves
We consider a orbifold, where acts by time and space
reversal, also known as the embedding space of the elliptic de Sitter space.
The background has two potentially dangerous problems: time-nonorientability
and the existence of closed time-like curves. We first show that closed causal
curves disappear after a proper definition of the time function. We then
consider the one-loop vacuum expectation value of the stress tensor. A naive
QFT analysis yields a divergent result. We then analyze the stress tensor in
bosonic string theory, and find the same result as if the target space would be
just the Minkowski space , suggesting a zero result for the
superstring. This leads us to propose a proper reformulation of QFT, and
recalculate the stress tensor. We find almost the same result as in Minkowski
space, except for a potential divergence at the initial time slice of the
orbifold, analogous to a spacelike Big Bang singularity. Finally, we argue that
it is possible to define local S-matrices, even if the spacetime is globally
time-nonorientable.Comment: 37 pages, LaTeX2e, uses amssymb, amsmath and epsf macros, 8 eps and 3
ps figures; (v2): Two additional comments + one reference added; (v3):
corrections in discussion of CTCs + some clarification
A comparison of flare forecasting methods. II. Benchmarks, metrics and performance results for operational solar flare forecasting systems
YesSolar flares are extremely energetic phenomena in our Solar System. Their impulsive,
often drastic radiative increases, in particular at short wavelengths, bring immediate
impacts that motivate solar physics and space weather research to understand solar
flares to the point of being able to forecast them. As data and algorithms improve
dramatically, questions must be asked concerning how well the forecasting performs;
crucially, we must ask how to rigorously measure performance in order to critically
gauge any improvements. Building upon earlier-developed methodology (Barnes et al.
2016, Paper I), international representatives of regional warning centers and research
facilities assembled in 2017 at the Institute for Space-Earth Environmental Research,
Nagoya University, Japan to â for the first time â directly compare the performance
of operational solar flare forecasting methods. Multiple quantitative evaluation metrics
are employed, with focus and discussion on evaluation methodologies given the restrictions of operational forecasting. Numerous methods performed consistently above the
âno skillâ level, although which method scored top marks is decisively a function of
flare event definition and the metric used; there was no single winner. Following in
this paper series we ask why the performances differ by examining implementation
details (Leka et al. 2019, Paper III), and then we present a novel analysis method to
evaluate temporal patterns of forecasting errors in (Park et al. 2019, Paper IV). With
these works, this team presents a well-defined and robust methodology for evaluating
solar flare forecasting methods in both research and operational frameworks, and todayâs performance benchmarks against which improvements and new methods may be
compared
Interactive effects of light, leaf temperature, CO 2 and O 2 on photosynthesis in soybean
A biochemical model of C 3 photosynthesis has been developed by G.D. Farquhar et al. (1980, Planta 149, 78â90) based on Michaelis-Menten kinetics of ribulose-1,5-bisphosphate (RuBP) carboxylase-oxygenase, with a potential RuBP limitation imposed via the Calvin cycle and rates of electron transport. The model presented here is slightly modified so that parameters may be estimated from whole-leaf gas-exchange measurements. Carbon-dioxide response curves of net photosynthesis obtained using soybean plants ( Glycine max (L.) Merr.) at four partial pressures of oxygen and five leaf temperatures are presented, and a method for estimating the kinetic parameters of RuBP carboxylase-oxygenase, as manifested in vivo, is discussed. The kinetic parameters so obtained compare well with kinetic parameters obtained in vitro, and the model fits to the measured data give r 2 values ranging from 0.87 to 0.98. In addition, equations developed by J.D. Tenhunen et al. (1976, Oecologia 26, 89â100, 101â109) to describe the light and temperature responses of measured CO 2 -saturated photosynthetic rates are applied to data collected on soybean. Combining these equations with those describing the kinetics of RuBP carboxylase-oxygenase allows one to model successfully the interactive effects of incident irradiance, leaf temperature, CO 2 and O 2 on whole-leaf photosynthesis. This analytical model may become a useful tool for plant ecologists interested in comparing photosynthetic responses of different C 3 plants or of a single species grown in contrasting environments.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47469/1/425_2004_Article_BF00395048.pd
TRY plant trait database â enhanced coverage and open access
Plant traitsâthe morphological, anatomical, physiological, biochemical and phenological characteristics of plantsâdetermine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to biodiversity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of traitâbased plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traitsâalmost complete coverage for âplant growth formâ. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and traitâenvironmental relationships. These traits have to be measured on individual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives
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REFINING OF MgX AND OTHER URANIUM-BEARING MATERIALS. Quarterly Progress Report
Investigations on problems related to the use of MgX and other feed materials in the Plant 6 U refinery at St. Louis, Mo., have continued, with emphasis on the extraction of process feeds by neutral ether. Results of Scheibel column extraction tests wtth neutral ether on a variety of pitchblende, MgX, and V-20 soda salt feed materials indicate that the addition of Fe to complex interfering elements can reduce U losses in raffinates to lower levels than are attainable with acid ether in the absence of Fe. The beneficial effect of neutral ether on transfer of contaminants, especially Mo, to the ether extract was substantiated. It is indicated that the inclusion of V-20 soda salt in a feed tends to increase U losses in extraction; the addition of Fe was shown to be advantageous here also. Sources and costs of added Fe are considered. (G.Y.
The Tradeoff Between Improved Monetary Control and Market Interest Rate Variability in Australia
Comprehensive Analysis of Binding Sites in Tubulin
Tubulin plays essential roles in vital cellular activities and is the target of a wide range of proteins and ligands. Here, using a combined computational and crystallographic fragment screening approach, we addressed the question of how many binding sites exist in tubulin. We identified 27 distinct sites, of which 11 have not been described previously, and analyzed their relationship to known tubulin\u2013protein and tubulin\u2013ligand interactions. We further observed an intricate pocket communication network and identified 56 chemically diverse fragments that bound to 10 distinct tubulin sites. Our results offer a unique structural basis for the development of novel small molecules for use as tubulin modulators in basic research applications or as drugs. Furthermore, our method lays down a framework that may help to discover new pockets in other pharmaceutically important targets and characterize them in terms of chemical tractability and allosteric modulation
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