bluuebunny/crossref_metadata_2025 huggingface dataset:
Resting Energy Expenditure: Systematic Organization and Critique of Prediction Methods
Authors: Wang ZiMian , Heshka Stanley , Zhang Kuan , Boozer Carol N. , Heymsfield Steven B.
Published: April 2008

There are many published methods for predicting resting energy expenditure (REE) from measured body composition. Although these published reports extend back almost a century, new related studies appear on a regular basis. It remains unclear what the similarities and differences are among these various methods and what, if any, advantages the newly introduced REE prediction models offer. These issues led us to develop an organizational system for REE prediction methods with the goal of clarifying prevailing ambiguities in the field. Our classification scheme is founded on body composition level (whole‐body, tissue‐organ, cellular, and molecular) and related components as the REE predictor variables. Each existing REE prediction method by body composition must belong to one body composition level. The suggested classification system, founded on a conceptual basis, highlights similarities and differences among the diverse REE‐body composition prediction methods, provides a framework for teaching REE‐body composition relationships, and identifies important future research opportunities.
Intracerebroventricular Glucocorticoid Infusion in Normal Rats: Induction of Parasympathetic‐Mediated Obesity and Insulin Resistance
Authors: Cusin Isabelle , Rouru Juha , Rohner‐Jeanrenaud Françoise
Published: April 2008

Objective: The aims of the present study were to determine whether increased body weight resulting from intracerebroventricular (ICV) glucocorticoid (dexamethasone) infusion in normal rats is associated, as in obesity, with changes in glucose metabolism and to investigate whether the parasympathetic nervous system is involved in the glucocorticoid‐induced effects.

Research Methods and Procedures: Male Sprague–Dawley rats were infused with ICV dexamethasone (2.5 μg/d) or its vehicle for 2 days during which food intake, body weight, and basal insulinemia were measured. Euglycemic–hyperinsulinemic clamps associated with the labeled 2‐deoxyglucose technique were then performed to determine the total rate of glucose disappearance and the tissue glucose use indices. Similar experiments were carried out in vagotomized rats.

Results: Two days of ICV glucocorticoid infusion in normal rats resulted in increases in food intake, body weight, basal insulinemia, and produced decreases in the insulin‐stimulated total rate of glucose disappearance, as well as in glucose use indices of all muscle types studied. None of these alterations was observed when glucocorticoid infusion was carried out in vagotomized rats.

Discussion: These data show that central glucocorticoid infusion favors anabolic processes, such as feeding behavior, body weight gain, and insulin output, while promoting muscle insulin resistance. These effects seem to be mediated by an activation of the parasympathetic nervous system, because they all disappear when tested in vagotomized rats.
The Effects of Leptin Administration in Non‐obese Human Subjects
Authors: Mackintosh Ronald M. , Hirsch Jules
Published: April 2008

Objective: Body fatness is partly under hypothalamic control with effector limbs that include the endocrine system and the autonomic nervous system (ANS). In previous studies of both obese and never‐obese subjects, we have shown that weight increase leads to increased sympathetic and decreased parasympathetic activity, whereas weight decrease leads to decreased sympathetic and increased parasympathetic activity. We now report on the effect of leptin, independent of weight change, on the ANS.

Research Methods and Procedures: Normal weight males (ages 20–40 years) were fed a solid food diet, measured carefully to maintain body weight, for 3 weeks, as inpatients at the Rockefeller University General Clinical Research Center. In a single‐blind, 22‐day, placebo/drug/placebo design, six subjects received leptin 0.3 mg/kilogram subcutaneously for 6 days. ANS measures of amount of parasympathetic control and sympathetic control of heart period (interbeat interval) were made by sequential pharmacological blockade with intravenous atropine and esmolol. Norepinephrine, dopamine, and epinephrine levels in 24‐hour urine collections were also measured as well as resting metabolic rate.

Results: Sufficient food intake maintained constant body weight in all subjects. There was no evidence that leptin administration led to changes in energy metabolism sufficient to require additional food intake or to alter resting metabolic rate. Likewise, leptin administration did not alter autonomic activity. Parasympathetic control and sympathetic control, as well as the urinary catecholamines, were not significantly affected by leptin administration. Glucose and insulin levels were increased by food intake as expected, but leptin had no affect on these levels before or after food intake.

Discussion: ANS responses to changes in energy metabolism found when food intake and body weight are altered were not found in these never‐obese subjects given leptin for 6 days. Although exogenous leptin administration has profound effects on food intake and energy metabolism in animals genetically deprived of leptin, we found it to have no demonstrable effect on energy metabolism in never‐obese humans. The effects of longer periods of administration to obese individuals and to those who have lost weight demand additional investigation.
Neck Circumference as a Simple Screening Measure for Identifying Overweight and Obese Patients
Authors: Ben‐Noun Liubov (Louba) , Sohar Ezra , Laor Arie
Published: April 2008

Objective: There are numerous methods of assessing overweight and obesity. We undertook an observational study to test a method of identifying overweight or obese patients solely by measuring the circumference of the neck.

Research Methods and Procedures: A test sample and a second validation sample included 979 subjects (460 men and 519 women), who visited a family medicine clinic in a southern Israeli urban district for any reason between the randomly chosen months of January and September 1998. Main outcome included neck, waist, and hip circumferences; body mass index (BMI); and waist:hip ratio measures.

Results: Pearson's correlation coefficients indicated a significant association between neck circumference (NC) and: BMI (men, r = 0.83; women, r = 0.71; each, p < 0.0001), age (men, r = 0.33; women, r = 0.36; each, p < 0.0001), weight (men, r = 0.7; women, r = 0.81; each, p < 0.0001), waist circumference (men, r = 0.86; women, r = 0.85; each, p < 0.0001), hip circumference (men, r = 0.62; women, r = 0.56; each, p < 0.0001), and waist:hip ratio (men, r = 0.66; women, r = 0.87; each, p < 0.0001). NC ≥37 cm for men and ≥34 cm for women were the best cutoff levels for determining the subjects with BMI ≥25.0 kg/m2 using the receiver output curve analysis. In the validation unrelated group, the test characteristics were excellent with 98% sensitivity, 89% specificity, and 94% accuracy for men, and 100% sensitivity, 98% specificity, and 99% accuracy for women. NC ≥39.5 cm for men and ≥36.5 cm for women were the best cutoff levels for determining the subjects with BMI ≥30 kg/m2 using the receiver output curve analysis. In the validation unrelated group, the test characteristics were excellent with 93% sensitivity, 90% specificity, and 91% accuracy for men, and 93% sensitivity, 98% specificity, and 97% accuracy for women.

Discussion: NC measurement is a simple and time‐saving screening measure that can be used to identify overweight and obese patients. Men with NC <37 cm and women with NC <34 cm are not to be considered overweight. Patients with NC ≥37 cm for men and ≥34 cm for women require additional evaluation of overweight or obesity status.
Obesity and Elevated Plasma Leptin Concentration in oMT1A‐o Growth Hormone Transgenic Mice
Authors: Oberbauer Anita M. , Runstadler Jonathan A. , Murray James D. , Havel Peter J.
Published: April 2008

OBERBAUER, A. M., JONATHAN A. RUNSTADLER, JAMES D. MURRAY, AND PETER J. HAVEL. Obesity and elevated plasma leptin concentration in oMT1A‐o growth hormone transgenic mice.

Objective: This study was undertaken to evaluate plasma leptin concentration in the regulatable ovine metallothionein‐ovine growth hormone (oMT1a‐oGH) transgenic (TG) mouse model of obesity.

Research Methods and Procedures: Transgene stimulus (zinc) was provided at 21 days of age to male and female wild‐type (WT) and TG mice. Plasma leptin concentrations were measured by radioimmunoassay at 42, 63, 84, and 105 days of age and from inactivated TG mice at 84 and 105 days.

Results: WT and TG mice did not differ significantly in plasma leptin concentration at any of the ages examined (42, 63, 84, and 105 days), although females showed consistently higher plasma leptin concentrations than males regardless of genotype throughout the duration of the study. Male and female TG mice in which the transgene was inactivated at 63 days had a 1.5‐fold to 3.5‐fold increase in plasma leptin concentration over WT mice and continuously activated TG mice at 84 and 105 days of age. The elevated plasma leptin concentration seen in the inactivated TG mice at 84 and 105 days of age reflects the >300% increase in white adipose tissue seen in this model and correlated with all adipose depot weights and overall body lipid at these later ages. When plasma leptin was expressed per gram of total body fat, the leptin adjusted for body lipid was significantly higher in WT mice than either continuously activated TG or activated and then inactivated TG groups.

Discussion: The inactivated TG mice in this study had higher plasma leptin levels with increasing total body adiposity, but the relative proportion of circulating leptin, on a total body lipid basis, was reduced when compared with the WT mice. This reduction was also observed in activated TG mice at the older ages. Although the absolute levels of circulating leptin were elevated in the inactivated TG animals, the amount of leptin produced per gram of fat was lowered. With the inactivation of the transgene, the leptin remained depressed after the removal of the elevated growth hormone. This represents a potential explanation for the ensuing hypertrophy of the fat depots and the abnormal phenotypic response of inactivated TG mice to elevated plasma leptin concentrations resulting in the development of obesity.
Bupropion for Weight Loss: An Investigation of Efficacy and Tolerability in Overweight and Obese Women
Authors: Gadde Kishore M. , Parker Corette B. , Maner Lauren G. , Wagner H. Ryan , Logue Eric J. , Drezner Marc K. , Krishnan K. Ranga R.
Published: April 2008

Objective: On the basis of the clinical observations that bupropion facilitated weight loss, we investigated the efficacy and tolerability of this drug in overweight and obese adult women.

Research Methods and Procedures: A total of 50 overweight and obese (body mass index: 28.0 to 52.6 kg/m2) women were included. The core component of the study was a randomized, double‐blind, placebo‐controlled comparison for 8 weeks. Bupropion or placebo was started at 100 mg/d with gradual dose increase to a maximum of 200 mg twice daily. All subjects were prescribed a 1600 kcal/d balanced diet and compliance was monitored with food diaries. Responders continued the same treatment in a double‐blind manner for an additional 16 weeks to a total of 24 weeks. There was additional single‐blind follow‐up treatment for a total of 2 years.

Results: Subjects receiving bupropion achieved greater mean weight loss (last‐observation‐carried‐forward analysis) over the first 8 weeks of the study (p = 0.0001): 4.9% ± 3.4% (n = 25) for bupropion treatment compared with 1.3% ± 2.4% (n = 25) for placebo treatment. For those who completed the 8 weeks, the comparison was 6.2% ± 3.1% (n = 18) vs. 1.6% ± 2.9% (n = 13), respectively(p = 0.0002), with 12 of 18 of the bupropion subjects (67%) losing over 5% of baseline body weight compared with 2 of 13 in the placebo group (15%; p = 0.0094). In the continuation phase, 14 bupropion responders who completed 24 weeks achieved weight loss of 12.9% ± 5.6% with fat accounting for 73.5% ± 3.7% of the weight lost and no change in bone mineral density as assessed by DXA. Bupropion was generally well‐tolerated in this sample.

Discussion: Bupropion was more effective than placebo in achieving weight loss at 8 weeks in overweight and obese adult women in this preliminary study. Initial responders to bupropion benefited further in the continuation phase.
The Relationship between Health‐Related Quality of Life and Weight Loss
Authors: Kolotkin Ronette L. , Crosby Ross D. , Williams G. Rhys , Hartley Guilford G. , Nicol Susan
Published: April 2008

Objective: This is a report of health‐related quality of life (HRQOL) changes in obese patients completing at least 1 year of outpatient treatment in a weight reduction program combining phentermine‐fenfluramine and dietary counseling.

Research Methods and Procedures: Participants were 141 women (87.6%) and 20 men (12.4%) who had an average body mass index at intake of 41.1 kg/m2 (SD = 7.0, range = 29.5 to 67.0 kg/m2) and an average age of 44.9 years (SD = 9.3, range = 23 to 65 years). HRQOL was assessed at intake and at 1‐year follow‐up using the Impact of Weight on Quality of Life (IWQOL)‐Lite questionnaire. The relationship between HRQOL changes and weight loss was examined using Pearson correlations. Clinically meaningful change in HRQOL was defined as a 1.96 SEM reduction in IWQOL‐Lite total score.

Results: On average, participants lost 20.2 kg or 17.6% of their weight over the 1‐year period. Of the participants, 15.5% lost <10% of their weight, 24.2% lost 10% to 14.9%, 23.6% lost 15% to 19.9%, and 36.6% lost 20% or more. All five IWQOL‐Lite scales and total score showed statistically significant improvement over the 1‐year period. Changes in IWQOL‐Lite scores from intake to 1 year showed statistically significant correlations with percentage of weight loss for all subscales and total score. Subscale correlations with weight loss ranged from 0.166 (Public Distress) to 0.396 (Physical Function) and was 0.370 for the total score. Forty‐four percent of participants losing <10% met the criterion of clinically meaningful change, compared with 51.3% losing 10% to 14.9%, 55.3% losing 15% to 19.95%, and 76.3% losing >20%. For total score and for three of the five IWQOL‐Lite scales (Physical Function, Self‐Esteem, and Sexual Life), the relationship between weight loss and clinically meaningful change was linear and was significant at p < 0.05. Physical Function and Self‐Esteem were most strongly affected by weight loss.

Discussion: HRQOL changes, as measured by an obesity‐specific instrument (IWQOL‐Lite), are strongly related to weight reduction.
Sex‐Dependent Dietary Obesity, Induction of UCPs, and Leptin Expression in Rat Adipose Tissues
Authors: Rodríguez Ana M. , Quevedo‐Coli Santiago , Roca Pilar , Palou Andreu
Published: April 2008

Objective: The aim of this study was to determine the sex‐dependent differences in the response of key parameters involved in thermogenesis and control of body weight in brown adipose tissue (BAT) and white adipose tissue (WAT) in postcafeteria‐fed rats, a model of dietary obesity.

Research Methods and Procedures: BAT and WAT were obtained from male and female control and postcafeteria‐fed Wistar rats. Postcafeteria‐fed rats were initially fed with cafeteria diet from day 10 of life until day 110 (cafeteria period) and with standard chow diet from then until day 180 of life (postcafeteria period). Body mass and energy intake were evaluated. Biometric parameters were analyzed in interscapular BAT (IBAT). Levels of uncoupling protein 1 (UCP1), α2‐adrenergic receptor (AR), and β3‐AR proteins and UCP1, UCP2, UCP3, β3‐AR, and leptin mRNAs, in IBAT or WAT, were studied by Western blot and Northern blot analyses, respectively.

Results: Rats attained 59% (females) and 39% (males) increase in body weight at the end of the cafeteria period. During the postcafeteria period, the rats showed a loss of body weight, which was higher in females. Postcafeteria‐fed female rats also presented higher activation of thermogenic parameters in IBAT, including UCP1, UCP2, and UCP3 mRNAs. Female control rats showed lower levels of both α2 and β3‐ARs in BAT compared with male rats, but these levels in postcafeteria‐fed female and male rats were the same, because males tended to down‐regulate them. Levels of leptin mRNA in response to the postcafeteria state depended on gender and the specific WAT depot studied.

Discussion: It is suggested that in postcafeteria‐fed female rats, BAT thermogenic capacity becomes more efficiently activated than in males. Female rats also showed a bigger weight loss. The parallel regulation of the levels of UCP2 and UCP3 mRNAs, with respect to UCP1 mRNA, with higher activation in female postcafeteria‐fed rats, suggests a possible role of both UCP2 and UCP3 in the regulation of energy expenditure and in the control of body weight. The distinct responses to overweight of α2 and β3‐ARs—which were sex dependent—and leptin mRNA—which depended on both sex and WAT depot—also support the different response of thermogenesis‐related parameters between overweight males and females.
Body Composition of African American and White Children: A 2‐Year Follow‐Up of the BAROC Study
Authors: Bray George A. , DeLany James P. , Harsha David W. , Volaufova Julia , Champagne Catherine M.
Published: April 2008

Objective: To evaluate the 2‐year changes in body composition of white and African American boys and girls.

Research Methods and Procedures: A total of 114 boys and girls ages 12 to 14 years with equal sex and ethnic distribution between African American and white races participated in measurements of body composition using DXA, underwater weighing (densitometry), skinfold thickness, corporal diameters, circumferences, isotope dilution (H218O), and bioelectric impedance.

Results: Sixty‐eight of the 114 children advanced from Tanner Stages 1 and 2 to Tanner Stages 3 to 5 over a 2‐year period. More than 50% of the children were in the top 15th percentile according to normative data for body mass index but not for triceps skinfold. All measures except for percentage of fat, density, and four of the six skinfolds increased significantly during the 2 years, with no differences between races, genders, or fat group. The boys who advanced in Tanner Stage reduced their percentage of fat and a number of skinfolds and increased their lean body mass, but the girls did not. The percentage of water was significantly higher in the fatter children and declined significantly over 2 years. Most children remained in the same quartile of body fat, lean body mass, and bone mineral content over 2 years.

Discussion: The data are consistent with the hypothesis that over 2 years, growth is the major determinant of changing body composition, with body‐fat group and sexual maturation being additional variables.
Obesity and Sarcopenia after Menopause Are Reversed by Sex Hormone Replacement Therapy
Authors: Sørensen Morten Beck , Rosenfalck Anne Mette , Højgaard Liselotte , Ottesen Bent
Published: April 2008

Objective: Menopause is linked to an increase in fat mass and a decrease in lean mass exceeding age‐related changes, possibly related to reduced output of ovarian steroids. In this study we examined the effect of combined postmenopausal hormone replacement therapy (HRT) on the total and regional distribution of fat and lean body mass.

Research Methods and Procedures: Sixteen healthy postmenopausal women (age: 55 ± 3 years) were studied in a placebo‐controlled, crossover study and were randomized to 17β estradiol plus cyclic norethisterone acetate (HRT) or placebo in two 12‐week periods separated by a 3‐month washout. Total and regional body composition was measured by DXA at baseline and in the 10th treatment week in both periods. Changes were compared by a paired Student's t test.

Results: The change in body weight during HRT was equal to the change during placebo (−24.6 g vs. −164 g, p = 0.42), but relative fat mass was significantly reduced (−0.5% vs. +1.24%, p < 0.01). During HRT, compared with during placebo, lean body mass increased (+347 g vs. −996 g, p < 0.01) and total fat mass decreased (−400 g vs. +836 g, p = 0.06). Total bone mineral content increased (+28.9 g vs. −4.4 g, p = 0.04) and abdominal fat decreased (−185 g vs. +253 g, p = 0.04) during HRT compared with placebo.

Discussion: HRT is linked to the reversal of both menopause‐related obesity and loss of lean mass, without overall change in body weight. The increase in lean body mass during HRT is likely explained by muscle anabolism, which in turn, prevents disease in the elderly.
Larger Hip Circumference Independently Predicts Health and Longevity in a Swedish Female Cohort
Authors: Lissner Lauren , Björkelund Cecilia , Heitmann Berit L. , Seidell Jaap C. , Bengtsson Calle
Published: April 2008

Objective: The waist circumference is widely viewed as a simple but effective measure for assessing obesity‐related health risks, whereas measurement of the hip circumference is not currently prioritized. This study examines health risks associated specifically with hip circumference in a cohort of Swedish women, to determine whether information may be lost by excluding the hip circumference from health surveys.

Research Methods and Procedures: The subjects described in this report constitute a population‐based sample of 38‐ to 60‐year‐old women who underwent anthropometric examinations in 1968. The 24‐year incidence rates have been ascertained for myocardial infarction, combined cardiovascular diseases, and diabetes. All‐cause, cardiovascular, and myocardial infarction mortality also were evaluated.

Results: Hip circumference was a significant independent inverse risk estimator for all endpoints studied. Using Cox regression with adjustment for age, smoking, body mass index, and waist circumference, the remaining variability associated with larger hips was associated with significantly fewer adverse health outcomes. The hip circumference became statistically informative after body mass index adjustment. The strongest protective associations were observed for cardiovascular disease and diabetes endpoints, although significant trends were also seen for total mortality. Considering hip and waist simultaneously, the strength of the inverse association for large hips generally exceeded the positive association for waist.

Discussion: Recent interest in the waist circumference as an effective screening tool has taken the focus off of the hip circumference. The present results suggest that collection of hip measurements should not be discontinued in assessment of obesity‐related risk status and health promotion.
The Effects of Metformin and Diet on Plasma Testosterone and Leptin Levels in Obese Men
Authors: Ozata Metin , Oktenli Cagatay , Bingol Necati , Ozdemir I. Caglayan
Published: April 2008

Objective: The aim of this study was to investigate the effects of combined hypocaloric diet and metformin on circulating testosterone and leptin levels in obese men with or without type 2 diabetes.

Research Methods and Procedures: Twenty obese men with type 2 diabetes (mean body mass index [BMI]: 35.5 ± 1.1 kg/m2) and 20 nondiabetic obese men were enrolled in the study. We measured serum follicle‐stimulating hormone, luteinizing hormone (LH), total testosterone (TT), free testosterone (FT), sex‐hormone‐binding globulin (SHBG), dehydroepiandrosterone sulfate (DHEAS), and plasma leptin levels before and 3 months after metformin treatment. Both groups were placed on a hypocaloric diet and 850 mg of metformin taken orally twice daily for 3 months.

Results: Metformin and hypocaloric diets led to decreases in BMI and waist and hip circumferences in both groups. A significant decrease in TT levels in the diabetic group and FT levels in the control group was found, whereas follicle‐stimulating hormone, LH, and DHEAS levels were not changed significantly. A significant increase in SHBG levels was observed in the control group but not in the patient group. Leptin levels also decreased after treatment in both groups. Decreased testosterone levels were not correlated to changes in waist and hip circumference, waist‐to‐hip ratio, BMI, and levels of fasting blood glucose, leptin, SHBG, or DHEAS in the diabetic group. However, a decrease in FT was correlated to changes in the levels of SHBG (r = −0.71, p = 0.001) and LH (r = 0.80, p = 0.001) but not to other parameters.

Discussion: We conclude that metformin treatment combined with a hypocaloric diet leads to reduced FT levels in obese nondiabetic men and to reduced TT levels in obese men with type 2 diabetes. Increased SHBG levels may account for the decrease in FT levels in the former group.
Effect of Satiation on Brain Activity in Obese and Lean Women
Authors: Gautier Jean‐François , Del Parigi Angelo , Chen Kewei , Salbe Arline D. , Bandy Daniel , Pratley Richard E. , Ravussin Eric , Reiman Eric M. , Tataranni Pietro Antonio
Published: April 2008

Objective: To investigate the response of the brains of women to the ingestion of a meal.

Research Methods and Procedures: We used measures of regional cerebral blood flow (rCBF), a marker of neuronal activity, by positron emission tomography to describe the functional anatomy of satiation, i.e., the response to a liquid meal in the context of extreme hunger (36‐hour fast) in 10 lean (BMI ≤ 25 kg/m2; 32 ± 10 years old, 61 ± 7 kg; mean ± SD) and 12 obese (BMI ≥ 35 kg/m2; 30 ± 7 years old, 110 ± 14 kg) women.

Results: In lean and obese women, satiation produced significant increases in rCBF in the vicinity of the prefrontal cortex (p < 0.005). Satiation also produced significant decreases in rCBF in several regions including the thalamus, insular cortex, parahippocampal gyrus, temporal cortex, and cerebellum (in lean and obese women), and hypothalamus, cingulate, nucleus accumbens, and amygdala (in obese women only; all p < 0.005). Compared with lean women, obese women had significantly greater increases in rCBF in the ventral prefrontal cortex and had significantly greater decreases in the paralimbic areas and in areas of the frontal and temporal cortex.

Discussion: This study indicates that satiation elicits differential brain responses in obese and lean women. It also lends additional support to the hypothesis that the paralimbic areas participate in a central orexigenic network modulated by the prefrontal cortex through feedback loops.
Does Waist Circumference Add to the Predictive Power of the Body Mass Index for Coronary Risk?
Authors: Iwao Satoshi , Iwao Nobuko , Muller Denis C. , Elahi Dariush , Shimokata Hiroshi , Andres Reubin
Published: April 2008

Objectives: To examine the power of the combined measurements of body mass index (BMI) and waist circumference (WC) for the prediction of abnormality in coronary heart disease risk factors and to determine whether the additional measurement of WC is predictive in older men and women.

Research Methods and Procedures: 1190 men and 751 women of the Baltimore Longitudinal Study of Aging were dichotomized into younger (<65 years) and older (65+ years) age groups. Coronary risk factors in the realms of glucose/insulin metabolism, blood pressure, and plasma lipids were assessed. The relationship of BMI and WC, singly and combined, to 10 risk factors for coronary heart disease was examined.

Results: In younger and older men and women, BMI and WC are highly correlated (0.84 to 0.88). BMI and WC are also significantly correlated to all 10 coronary risk factors in younger men and women and to 8 of the 10 in the older men and women. Both partial correlation and logistic regression analyses revealed a modest but significant improvement in the prediction of coronary risk in younger men and women by WC after controlling for the level of BMI. There was no improvement in the older subjects.

Discussion: WC adds only modestly to the prediction of coronary risk in younger subjects once BMI is known, and adds nothing to the production of risk in older subjects.
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anion and new carbenic isomers of cyanodiacetylene: A matrix isolation IR study
Authors: Coupeaud Anne , Turowski Michał , Gronowski Marcin , Piétri Nathalie , Couturier-Tamburelli Isabelle , Kołos Robert , Aycard Jean-Pierre
Published: April 2008

Products of the vacuum-UV photolysis of cyanodiacetylene (HC5N) in solid argon—the anion C5N−, imine HNC5, and the branched carbene C4(H)CN—have been identified by IR absorption spectroscopy, in addition to the already discovered isonitrile HC4NC. Spectral assignments were assisted by deuterium substitution experiments, by BD(T) calculations, and by the results of a recent density functional theory study.
The Euclidean gravitational action as black hole entropy, singularities, and spacetime voids
Authors: Castro Carlos
Published: April 2008

We argue why the static spherically symmetric vacuum solutions of Einstein’s equations described by the textbook Hilbert metric gμν(r) is not diffeomorphic to the metric gμν(∣r∣) corresponding to the gravitational field of a point mass delta function source at r=0. By choosing a judicious radial function R(r)=r+2G∣M∣Θ(r) involving the Heaviside step function, one has the correct boundary condition R(r=0)=0, while displacing the horizon from r=2G∣M∣ to a location arbitrarily close to r=0 as one desires, rh→0, where stringy geometry and quantum gravitational effects begin to take place. We solve the field equations due to a delta function point mass source at r=0, and show that the Euclidean gravitational action (in ℏ units) is precisely equal to the black hole entropy (in Planck area units). This result holds in any dimensions D⩾3. In the Reissner–Nordstrom (massive charged) and Kerr–Newman black hole case (massive rotating charged) we show that the Euclidean action in a bulk domain bounded by the inner and outer horizons is the same as the black hole entropy. When one smears out the point-mass and point-charge delta function distributions by a Gaussian distribution, the area-entropy relation is modified. We postulate why these modifications should furnish the logarithmic corrections (and higher inverse powers of the area) to the entropy of these smeared black holes. To finalize, we analyze the Bars–Witten stringy black hole in 1+1 dimension and its relation to the maximal acceleration principle in phase spaces and Finsler geometries.
Bubble velocity in the nonlinear Rayleigh–Taylor instability at a deflagration front
Authors: Modestov Mikhail , Bychkov Vitaly , Betti Riccardo , Eriksson Lars-Erik
Published: April 2008

The Rayleigh–Taylor instability at a deflagration front is studied systematically using extensive direct numerical simulations. It is shown that, for a sufficiently large gravitational field, the effects of bubble rising dominate the deflagration dynamics. It is demonstrated both analytically and numerically that the deflagration speed is described asymptotically by the Layzer theory in the limit of large acceleration. In the opposite limit of small and zero gravitational field, intrinsic properties of the deflagration front become important. In that case, the deflagration speed is determined by the velocity of a planar front and by the Darrieus–Landau instability. Because of these effects, the deflagration speed is larger than predicted by the Layzer theory. An analytical formula for the deflagration speed is suggested, which matches two asymptotic limits of large and small acceleration. The formula is in good agreement with the numerical data in a wide range of Froude numbers. The present results are also in agreement with previous numerical simulations on this problem.
Matrix isolation IR spectroscopic and ab initio studies of C3N− and related species
Authors: Kołos Robert , Gronowski Marcin , Botschwina Peter
Published: April 2008

Coupled cluster calculations were carried out for C3N−, CCNC−, C3N, CCNC, C3N+, and C3O. They support the experimental identification of the C3N− ion by means of matrix isolation infrared (IR) spectroscopy. The anion was generated in electric discharges through the cyanoacetylene isotopomers HC3N14, HC3N15, and H2C3N, trapped in cryogenic rare gas matrices (Ne, Ar, Kr), and detected via its two most intense IR absorption bands, assigned to the ν1 and ν2 stretching vibrations. C3N− appears to be quite a stable anion, with a vertical detachment energy predicted to be as high as 4.42eV. A large equilibrium electric dipole moment of 3.10D facilitates the investigation of C3N− by microwave spectroscopy and radio astronomy. Various structural parameters and spectroscopic properties have been calculated for all tetra-atomic species considered.
Dynamical decoupling schemes derived from Hamilton cycles
Authors: Rötteler Martin
Published: April 2008

We address the problem of decoupling the interactions in a spin network governed by a pair-interaction Hamiltonian. Combinatorial schemes for decoupling and for manipulating the couplings of Hamiltonians have been developed, which use selective pulses. In this paper, we consider an additional requirement on these pulse sequences: as few different control operations as possible should be used. This requirement is motivated by the fact that to find an optimal implementation of each individual selective pulse will be expensive since it requires to solve a pulse shaping problem. Hence, it is desirable to use as few different selective pulses as possible. As a first result, we show that for d-dimensional systems, where d⩾2, the ability to implement only two control operations is sufficient to turn off the time evolution. Next, we address the case of a bipartite system with local control and show that four different control operations are sufficient. Finally, turning to networks consisting of several d-dimensional nodes, we show that decoupling can be achieved if one is able to control a number of different control operations, which is logarithmic in the number of nodes. We give an explicit family of efficient decoupling schemes with logarithmic number of different pulses based on the classic Hamming codes. We also provide a table of the best known decoupling schemes for small networks of qubits.
Transport and magnetic properties of NdCuGe compound
Authors: Goruganti V. , Rathnayaka K. D. D. , Ross Joseph H. , Öner Y. , Lue C. S. , Kuo Y. K.
Published: April 2008

Electrical resistivity, heat capacity, and dc magnetization measurements were performed on the AlB2-type intermetallics NdCuGe and LaCuGe over the temperature range of 2–300K. NdCuGe exhibits magnetization attributable to Nd3+ moments, with an antiferromagnetic (AF) transition at 3.1K. Magnetization, heat capacity, and resistivity measurements were used to determine the crystalline electric field (CEF) splitting of the Nd3+ magnetic sublevels. The ground state is a doublet composed of ±5∕2 levels and the AF state is built from this magnetic doublet, with a reduction in the average sublattice magnetization attributable to site disorder among Cu–Ge sites. Low-temperature electrical transport is dominated by spin-disorder scattering among CEF-split levels and a small T2 spin fluctuation term. The latter is nearly two orders of magnitude smaller than previously observed in isostructural CeCuGe, for which the anomalous observed thermopower exponent was attributed to extended spin fluctuations above the magnetic transition. By contrast, simple-metallic behavior provides a good fit to the NdCuGe thermopower, thus, the CeCuGe results can be attributed to resonant scattering due to partial hybridization of the localized orbitals.
Precisely tunable continuous-wave terahertz source with interferometric frequency control
Authors: Deninger Anselm J. , Göbel Thorsten , Schönherr Daniel , Kinder Thomas , Roggenbuck Axel , Köberle Markus , Lison Frank , Müller-Wirts Thomas , Meissner Peter
Published: April 2008

We realized a tunable continuous-wave terahertz source with megahertz frequency resolution. The system is based on optical heterodyning of two near-infrared distributed feedback diode lasers, each laser being stabilized by electronic feedback from a low-finesse quadrature interferometer. The control loop permits precisely linear laser frequency scans over >1200GHz, and a beat signal linewidth of 1MHz at 80ms time scale. Using GaAs photomixers and log-periodic antennae, we achieve a signal-to-noise ratio of the terahertz power of >70dB at 100GHz and 100ms integration time, and still ∼30dB at 1THz. As an example for high-resolution terahertz spectroscopy, we characterize the transmission properties of a subwavelength metal grating.
Gamma-ray waveguides
Authors: Tournear D. M. , Hoffbauer M. A. , Akhadov E. A. , Chen A. T. , Pendleton S. J. , Williamson T. L. , Cha K. C. , Epstein R. I.
Published: April 2008

We have developed an approach for gamma-ray optics using layered structures acting as planar waveguides. Experiments demonstrating channeling of 122keV gamma rays in two prototype waveguides validate the feasibility of this technology. Gamma-ray waveguides allow one to control the direction of radiation up to a few MeV. The waveguides are conceptually similar to polycapillary optics, but can function at higher gamma-ray energies. Optics comprised of these waveguides will be able to collect radiation from small solid angles or concentrate radiation into small area detectors. Gamma-ray waveguides may find applications in medical imaging and treatment, astrophysics, and homeland security.
Ultra-high-precision time control system over any long time delay for laser pump and synchrotron x-ray probe experiment
Authors: Fukuyama Yoshimitsu , Yasuda Nobuhiro , Kim Jungeun , Murayama Haruno , Ohshima Takashi , Tanaka Yoshihito , Kimura Shigeru , Kamioka Hayato , Moritomo Yutaka , Toriumi Koshiro , Tanaka Hitoshi , Kato Kenichi , Ishikawa Tetsuya , Takata Masaki
Published: April 2008

An ultra-high-precision clock system for long time delay has been developed for picosecond time-resolved x-ray diffraction measurements using synchrotron radiation (SR) pulses and synchronized femtosecond laser pulses. The time delay control between pump laser pulse and the probe SR pulse was achieved by combining an in-phase quadrature modulator and a synchronous counter. This method allowed us to change the delay time by a nearly infinite amount while maintaining the precision of ±8.40ps. Time-resolved diffraction measurements using the delay control system were demonstrated for precise measurement of an acoustic velocity in a single crystal of gallium arsenide.
Time-dependent fields and anisotropy dominated magnetic media
Authors: Rivkin K. , Tabat N. , Foss-Schroeder S.
Published: April 2008

We use a single dipole approximation to analyze the behavior of anisotropy dominated magnetic nanoparticles subjected to an external rf field. Analysis of the steady state oscillations and their stability reveals the optimal conditions for the magnetization reversal by a combination of constant frequency rf field and a dc field.
Origin of substantial plastic deformation in Gum Metals
Authors: Xing H. , Sun J. , Yao Q. , Guo W. Y. , Chen R.
Published: April 2008

The elastic property and structure of dislocation in Gum Metal are investigated by anisotropic elastic theory and high-resolution transmission electron microscopy (HRTEM). The results show that the elastic energy coefficients for the 1∕2⟨111⟩ perfect dislocations nearly equal to zero as the shear modulus along ⟨111⟩{110}, {112}, {123} when the valence electron number e∕a reaches 4.2, which implies a low intrinsic critical resolved shear stress for dislocation glide. HRTEM observations further revealed 70.53° dislocations in Gum Metal after severe cold working. The substantial plastic deformation is considered to originate from the conventional dislocation mechanism, rather than from the dislocation-free mechanism in Gum Metals.
Electrical properties of pulsed UV laser irradiated amorphous carbon
Authors: Miyajima Y. , Adikaari A. A. D. T. , Henley S. J. , Shannon J. M. , Silva S. R. P.
Published: April 2008

Amorphous carbon films containing no hydrogen were irradiated with a pulsed UV laser in vacuum. Raman spectroscopy indicates an increase in the quantity of sp2 clustering with the highest laser energy density and a commensurate reduction in resistivity. The reduction of resistivity is explained to be associated with thermally induced graphitization of amorphous carbon films. The high field transport is consistent with a Poole–Frenkel type transport mechanism via neutral trapping centers related to sp2 sites which are activated under high fields. Decreasing the resistivity is an important feature for use of carbon as an electronic material.
Structural disordering process of an amorphous alloy driven by the elastostatic compression at room temperature
Authors: Lee Sang-Chul , Lee Chang-Myeon , Lee Jae-Chul , Kim Hwi-Jun , Shibutani Yoji , Fleury Eric , Falk Michael L.
Published: April 2008

This study demonstrates that permanent deformation results when an amorphous alloy is subjected to a stress below yield at room temperature. The resultant deformation was observed to be homogeneous and is thought to occur as a result of the structural disordering, in which densely packed short-range ordered clusters break down to form new, loosely packed ones. It was found that this disordering process is irreversible even if the applied stress is removed, resulting in the creation of excess free volume. These findings were analyzed using the molecular dynamics simulations in the light of atomic-scale structural changes.
Optical properties of InxAl1−xAs alloy films
Authors: Yoon J. J. , Ghong T. H. , Byun J. S. , Kim Y. D. , Aspnes D. E. , Kim H. J. , Chang Y. C. , Song J. D.
Published: April 2008

Pseudodielectric functions ⟨ε⟩ of InxAl1−xAs ternary alloy films were determined from 1.5to6.0eV by spectroscopic ellipsometry. We minimized overlayer effects by performing wet-chemical etching to more accurately determine intrinsic bulk dielectric responses. Energies of the E1, E1+Δ1, E0′, E2, E2+Δ2 and E2′ critical points (CPs) were identified by band structure calculations of the linear augmented Slater-type orbital method. These calculations also showed a crossing of the E0′ and E2 CP structures with increasing In composition and a new saddle point in the AlAs band structure.
Coupling length of silicon-on-insulator directional couplers probed by Fourier-space imaging
Authors: Jágerská J. , Le Thomas N. , Houdré R. , Beggs D. M. , O’Brien D. , Krauss T. F.
Published: April 2008

We use a Fourier-space imaging technique relying on outcoupling grating probes to study the coupled mode interaction and dispersion properties of guided modes in silicon-on-insulator codirectional couplers. Our approach allows us to measure the mode splitting inherent to coupled systems, determine the mode symmetry, and locally probe the coupling length with an accuracy of ±50nm. A systematic study of directional couplers with different waveguide widths, coupling gaps, and e-beam exposure doses is reported in order to verify the results across a wider parameter space.
Nonvolatile memory with molecule-engineered tunneling barriers
Authors: Hou Tuo-Hung , Raza Hassan , Afshari Kamran , Ruebusch Daniel J. , Kan Edwin C.
Published: April 2008

We report a novel field-sensitive tunneling barrier by embedding C60 in SiO2 for nonvolatile memory applications. C60 is a better choice than ultrasmall nanocrystals due to its monodispersion. Moreover, C60 provides accessible energy levels to prompt resonant tunneling through SiO2 at high fields. However, this process is quenched at low fields due to highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) gap and large charging energy of C60. Furthermore, we demonstrate an improvement of more than an order of magnitude in retention to program/erase time ratio for a metal nanocrystal memory. This shows promise of engineering tunnel dielectrics by integrating molecules in the future hybrid molecular-silicon electronics.
Reduction of photoleakage current in polycrystalline silicon thin-film transistor using NH3 plasma treatment on buffer layer
Authors: Lu Hau-Yan , Chang Ting-Chang , Liu Po-Tsun , Li Hung-Wei , Hu Chin-Wei , Lin Kun-Chin , Wang Chao-Chun , Tai Ya-Hsiang , Chi Sien
Published: April 2008

The technology of polycrystalline silicon thin-film transistors (poly-Si TFTs) with low photoleakage current is developed in this work. The electrical characteristics of poly-Si TFTs under illumination were significantly improved employing the NH3 plasma treatment on the buffer layer, with no need for complicate device structure and additional masks. The trap states that originated from the plasma bombardment on the interface between the poly-Si layer and buffer oxide can effectively recombine the light-induced electron-hole pairs. The fewer residual electron-hole pairs lead to the lower photoleakage current and improved subthreshold swing, as well as maintaining good electrical characteristics in the dark sate.
Highly reproducible fabrication of back-gated GaAs∕AlGaAs heterostructures using AuGeNi ohmic contacts with initial Ni layer
Authors: Valeille Arnaud , Muraki Koji , Hirayama Yoshiro
Published: April 2008

We show for back-gated GaAs∕AlxGa1−xAs heterostructures that a thin Ni layer deposited prior to the standard AuGeNi Ohmic contacts dramatically improves the device yield by keeping the annealed contacts from reaching the back gate 1.2μm below the channel. A systematic investigation of the contact resistance and the back-gate characteristics as a function of the initial Ni layer thickness and the annealing temperature demonstrates that back-gated structures with contact resistance below 100Ω can be obtained with a high yield of 90%.
Scent evolution in Chinese roses
Authors: Scalliet Gabriel , Piola Florence , Douady Christophe J. , Réty Stéphane , Raymond Olivier , Baudino Sylvie , Bordji Karim , Bendahmane Mohammed , Dumas Christian , Cock J. Mark , Hugueney Philippe
Published: April 2008

The phenolic methyl ether 3,5-dimethoxytoluene (DMT) is a major scent compound of many modern rose varieties, and its fragrance participates in the characteristic “tea scent” that gave their name to Tea and Hybrid Tea roses. Among wild roses, phenolic methyl ether (PME) biosynthesis is restricted to Chinese rose species, but the progenitors of modern roses included both European and Chinese species (e.g.,
Rosa chinensis
cv Old Blush), so this trait was transmitted to their hybrid progeny. The last steps of the biosynthetic pathways leading to DMT involve two methylation reactions catalyzed by the highly similar orcinol
O
-methyltransferases (OOMT) 1 and 2. OOMT1 and OOMT2 enzymes exhibit different substrate specificities that are consistent with their operating sequentially in DMT biosynthesis. Here, we show that these different substrate specificities are mostly due to a single amino acid polymorphism in the phenolic substrate binding site of OOMTs. An analysis of the
OOMT
gene family in 18 species representing the diversity of the genus
Rosa
indicated that only Chinese roses possess both the
OOMT2
and the
OOMT1
genes. In addition, we provide evidence that the Chinese-rose-specific
OOMT1
genes most probably evolved from an
OOMT2
-like gene that has homologues in the genomes of all extant roses. We propose that the emergence of the
OOMT1
gene may have been a critical step in the evolution of scent production in Chinese roses.