BACKGROUND:Maternal obesity and diabetes are both associated with increased risk of congenital central nervous system (CNS) malformations in the offspring and may share a common underlying mechanism. Our objective was to evaluate whether gestational diabetes influenced the association of prepregnancy maternal obesity and risks for CNS birth defects. METHODS:This Texas population-based case-control study evaluated births occurring January 1997 through June 2001. Data came from structured telephone interviews. Cases (n=477) were mothers of offspring with anencephaly (n=120), spina bifida (n=184), holoprosencephaly (n=49), or isolated hydrocephaly (n=124). Controls (n=497) were mothers of live infants without abnormalities randomly selected from the same hospitals as cases. Response rates were approximately 60% for both cases and controls. We evaluated maternal obesity (body mass index > or =30.0 kg/m) and risks for CNS birth defects, as well as whether gestational diabetes influenced the risks. RESULTS:After adjusting for maternal ethnicity, age, education, smoking, alcohol use, and periconceptional vitamin use, obese women had substantially increased risks of delivering offspring with anencephaly (odds ratio=2.3; 95% confidence interval=1.2-4.3), spina bifida (2.8; 1.7-4.5), or isolated hydrocephaly (2.7; 1.5-5.0), but not holoprosencephaly (1.4; 0.5-3.8). Odds ratios were higher for the joint effects of maternal obesity and gestational diabetes, with evidence for interaction on a multiplicative scale. CONCLUSIONS:Maternal obesity and gestational diabetes may increase the risk of CNS birth defects through shared causal mechanisms.

The use of folic acid is a critical component in preventing birth defects. Health-care providers should take advantage of all health-care visits to counsel not only women at high risk (i.e., those with a history of having an infant with a neural tube defect [NTD]) but all women regarding the importance of folic acid use. A study conducted in Texas confirmed that white and Hispanic mothers were equally likely to recall receiving postpartum advice to use folic acid; however, Hispanic women were much less likely to use folic acid, compared with white women. This report covers data from May 2000 through November 2001. A study was conducted in Texas to determine whether women at high risk recall and follow recommendations to use folic acid. The study included 195 women at high risk and 223 control mothers who gave birth to infants without birth defects. These women participated in a telephone interview for a population-based case-control study of NTDs. Approximately 56.4% (110 of 195) of mothers who had infants affected by an NTD recalled receiving postpartum advice to use folic acid, compared with 25.6% (57 of 223) of control mothers (p < 0.01). Among nonpregnant case mothers, 54 (32.7%) of 165 reported regular use of supplements containing folic acid, and 53 (25.2%) of 210 nonpregnant control mothers reported this behavior (p = 0.11). Among case mothers, use of folic acid was significantly higher for whites (64.7%) versus Hispanics (16.5%) (p < 0.001); for women with some college education (57.1%) versus no college education (20.2%; p < 0.001); for women who were trying to get pregnant (66.7%) versus those using birth control (38.3%) or reporting using no contraceptive method (18.8%) (p = 0.001); and for women who reported receiving advice to use folic acid (40.9%) versus those who did not (22.2%; p = 0.01). Findings from this study support the need to implement NTD recurrence prevention activities in Texas. Data also identify a need for educational strategies in Texas that target Hispanic women at high risk, especially those who primarily speak Spanish. Further efforts should be made to determine why Hispanic women have low rates of folic acid use (e.g., the cost of vitamins and language and cultural barriers). On the basis of a review of research and current practice, recommendations developed by the Public Health Service include 1) women at risk for a recurrent NTD-affected pregnancy should take 0.4 mg of folic acidper day; and 2) if a woman at high risk is planning a pregnancy, she should consult her physician regarding taking the higher dose of 4.0 mg per day.

BACKGROUND Approximately 85% of primary congenital hypothyroidism (CH) is sporadic and due to malformations of the thyroid gland. Past studies have reported an increased birth weight among infants with CH. We have attempted to replicate and expand these observations, examining the association between different birth weight categories and CH stratified by infant's sex. We have also examined the prevalence of CH by mother's age and infant's ethnicity, gender, and year of birth. METHODS A cross-sectional study was conducted on 5, 049,185 infants screened by the statewide California Newborn Screening Program between 1990 and 1998, an estimated 98.6% of all newborns in the state. Dried blood spots from a heel stick were assayed for thyroxine (T4), and presumptive positives had follow-up assays of thyroid-stimulating hormone (TSH) to determine definite positives. RESULTS A total of 1,806 cases of CH were identified. The following findings are unlikely to be due to chance. Compared with infants with birth weights of 3,000-3,499 g, infants weighing <2,000 g and those weighing >/=4,500 g had a twofold or greater increase in the prevalence of CH. This was not explained as a result of confounding by the infant's ethnicity or gender. Compared with whites, elevated prevalence rates were found in most ethnic groups, which include the following: Hispanics, Chinese, Vietnamese, Asian Indians, Filipinos, Middle Easterners, and Hawaiians. As reported previously, black infants had about one-third the prevalence rate of whites. We also observed the frequently described female preponderance of CH. The female excess was maintained at all birth weights, however it varied by infant's ethnicity. Trends in the prevalence of CH were not associated with mother's age or with the time interval between 1990 and 1998. CONCLUSIONS We observed an increased risk of CH in both low-birth-weight (<2,000-g) and macrosomic (>/=4,500-g) infants. This U-shaped association has not been described in past studies. We have also expanded the previously described ethnic differences in CH risk to include ethnic groups not previously studied. The unique pattern of CH occurrence suggests that further studies to define modifiable risk factors may be useful.

The Thompson cross section for scattering of electromagnetic waves by a free electron in an expanding universe is derived here. The equations of motion of the electron are obtained using the Einstein-Infeld-Hoffmann (EIH) surface integral method. These integrals are evaluated approximately by perturbing off an Einstein-deSitter cosmological field. It is found that the Thompson cross section varies with time as the inverse square of the cosmic scale factor R(t).

The nexus between the gravitational field and the space-time metric was an essential element in Einstein's development of General Relativity and led him to his discovery of the field equations for the gravitational field/metric. I will argue here that the metric is in fact an inessential element of this theory and can be dispensed with entirely. Its sole function in the theory was to describe the space-time measurements made by ideal clocks and rods. However, the behavior of model clocks and measuring rods can be derived directly from the field equations of General Relativity using the Einstein-Infeld-Hoffmann (EIH) approiximation procedure. Therefore one does not need to introduce these ideal clocks and rods and hence has no need of a metric.

Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Twitter Facebook Reddit LinkedIn Tools Icon Tools Reprints and Permissions Cite Icon Cite Search Site Citation James L. Anderson; Answer to Question ♯15 [‘‘What space scales participate in cosmic expansion?,’’ Frank Munley, Am. J. Phys. 63(4), 297 (1995)]. Am. J. Phys. 1 May 1996; 64 (5): 527–528. https://doi.org/10.1119/1.18145 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAmerican Association of Physics TeachersAmerican Journal of Physics Search Advanced Search |Citation Search

The Solid State Imaging (SSI) experiment on the Galileo Orbiter spacecraft utilizes a high-resolution (1500 mm focal length) television camera with an 800 × 800 pixel virtual-phase, charge-coupled detector. It is designed to return images of Jupiter and its satellites that are characterized by a combination of sensitivity levels, spatial resolution, geometric fiedelity, and spectral range unmatched by imaging data obtained previously. The spectral range extends from approximately 375 to 1100 nm and only in the near ultra-violet region (∼ 350 nm) is the spectral coverage reduced from previous missions. The camera is approximately 100 times more sensitive than those used in the Voyager mission, and, because of the nature of the satellite encounters, will produce images with approximately 100 times the ground resolution (i.e., ∼ 50 m lp-1) on the Galilean satellites. We describe aspects of the detector including its sensitivity to energetic particle radiation and how the requirements for a large full-well capacity and long-term stability in operating voltages led to the choice of the virtual phase chip. The F/8.5 camera system can reach point sources of V(mag) ∼ 11 with S/N ∼ 10 and extended sources with surface brightness as low as 20 kR in its highest gain state and longest exposure mode. We describe the performance of the system as determined by ground calibration and the improvements that have been made to the telescope (same basic catadioptric design that was used in Mariner 10 and the Voyager high-resolution cameras) to reduce the scattered light reaching the detector. The images are linearly digitized 8-bits deep and, after flat-fielding, are cosmetically clean. Information ‘preserving’ and ‘non-preserving’ on-board data compression capabilities are outlined. A special “summation” mode, designed for use deep in the Jovian radiation belts, near Io, is also described. The detector is ‘preflashed’ before each exposure to ensure the photometric linearity. The dynamic range is spread over 3 gain states and an exposure range from 4.17 ms to 51.2 s. A low-level of radial, third-order, geometric distortion has been measured in the raw images that is entirely due to the optical design. The distortion is of the pincushion type and amounts to about 1.2 pixels in the corners of the images. It is expected to be very stable.

The relationship between reported coffee consumption and specific causes of death was examined in 9484 males enrolled in the Adventist Mortality Study in 1960 and followed through 1985. Coffee consumption was divided into three levels: less than 1 cup per day, 1-2 cups per day, and greater than or equal to 3 cups per day. Approximately one third of the subjects did not drink coffee. Cause-specific mortality rates were compared using survival analysis including Cox's proportional hazard model, and controlling for potential confounders such as body mass index, heart disease and hypertension at baseline, race, physical activity, marital status, educational level, smoking history, and dietary pattern. Inclusion of interaction terms between coffee consumption and attained age as time-dependent covariates allowed the hazard ratio to vary with age. Univariate analyses showed a statistically significant association (p less than 0.05) for coffee consumption and mortality for most endpoints. Multivariate analyses showed a small but statistically significant association between coffee consumption and mortality from ischemic heart disease, other cardiovascular diseases, all cardiovascular diseases, and all causes of death. For the major causes of death, the hazard ratios decreased from about 2.5 at 30 years of age to 1.0 around 95 years of age. These results indicate that abstinence from coffee leads to compression of mortality rather than an increase in lifespan.

The use of retarded potentials in solving the wave equation is usually justified on physical grounds or else by an appeal to causality. It is shown here that these potentials are asymptotic solutions obtained by solving the wave equation as an initial value problem and imposing only the condition that the initial field energy be finite. The relation of this result to the so-called electromagnetic arrow of time is discussed.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTA TRIBUTE TO PROFESSOR LOCKHART BURGESS ("BUCK") ROGERSJames A. de Haseth and James L. AndersonCite this: Anal. Chem. 1992, 64, 13, 687A–688APublication Date (Print):July 1, 1992Publication History Published online31 May 2012Published inissue 1 July 1992https://pubs.acs.org/doi/10.1021/ac00037a728https://doi.org/10.1021/ac00037a728research-articleACS PublicationsRequest reuse permissionsArticle Views21Altmetric-Citations1LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts

The relationship between reported coffee consumption and specific causes of death was examined in 9484 males enrolled in the Adventist Mortality Study in 1960 and followed through 1985. Coffee consumption was divided into three levels: 3 cups per day. Approximately one third of the subjects did not drink coffee. Cause-specific mortality rates were compared using survival analysis including Cox's proportional hazard model, and controlling for potential confounders such as body mass index, heart disease and hypertension at baseline, race, physical activity, marital status, educational level, smoking history, and dietary pattern. Inclusion of interaction terms between coffee consumption and attained age as time-dependent covariates allowed the hazard ratio to vary with age. Univariate analyses showed a statistically significant association (p < 0.05) for coffee consumption and mortality for most endpoints. Multivariate analyses showed a small but statistically significant association between coffee consumption and mortality from ischemic heart disease, other cardiovascular diseases, all cardiovascular diseases, and all causes of death. For the major causes of death, the hazard ratios decreased from about 2.5 at 30 years of age to 1.0 around 95 years of age. These results indicate that abstinence from coffee leads to compression of mortality rather than an increase in lifespan.

The relativistic generalization of fluctuation-dissipation-theorems for a dilute relativistic gas are derived both on the level of the relativistic Boltzmann-Langevin equation and of the relativistic hydrodynamics. The second moments of the fluctuating heat flow and stress-tensor are calculated by two different approaches analogous to the methods of Fox and Uhlenbeck and Landau and Lifshitz. The results are the naturally covariant generalization of the nonrelativistic results of these authors.

Newton’s first two laws of motion are often taken to be a definition of force. It is argued that they are true laws in that they make statements about the nature of the physical world. In particular, the first law can be viewed as asserting the existence of an ensemble of trajectories in a four-dimensional space along which force-free bodies, if they exist, would move. Such an ensemble, together with Newton’s absolute time, constitute the essential ingredients of the underlying geometrical structure of Newtonian space-time. If this view is accepted, it is a relatively simple matter to describe how special and general relativity differ from Newtonian mechanics.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSpectroelectrochemical response and flow hydrodynamics in thin-layer flow detectors with long optical path lengths and fiber-optic or slab waveguide couplingLawrence E. Fosdick and James L. AndersonCite this: Anal. Chem. 1988, 60, 2, 163–168Publication Date (Print):January 15, 1988Publication History Published online1 May 2002Published inissue 15 January 1988https://doi.org/10.1021/ac00153a013RIGHTS & PERMISSIONSArticle Views50Altmetric-Citations13LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (793 KB) Get e-Alerts Get e-Alerts

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSpectroelectrochemical response and optical geometry optimization of thin-layer flow detectors with long optical path lengths: theoryLawrence E. Fosdick and James L. AndersonCite this: Anal. Chem. 1988, 60, 2, 156–162Publication Date (Print):January 15, 1988Publication History Published online1 May 2002Published inissue 15 January 1988https://doi.org/10.1021/ac00153a012Request reuse permissionsArticle Views46Altmetric-Citations7LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts

A procedure is presented for dealing with “fast” radiating systems. It employs a method of matching a numerical solution in the source region to an analytic solution in the outer region. As a test of its effectiveness it is applied to a simple radiating system composed of a nonrelativistic harmonic oscillator coupled to a spherically symmetric scalar field. The effects of radiation damping on the oscillator are readily calculated and agree with the exact analytic predictions that one can derive. The accuracy of the “monopole formula” is checked and shown to fail in the fast-motion regime. It is also shown that the asymptotic damping of the system is independent of the initial conditions as long as the total energy is positive and constant. An instability of the system is also discussed.