bluuebunny/crossref_metadata_2025 huggingface dataset:
Exploring the geoengineering of climate using stratospheric sulfate aerosols: The role of particle size
Authors: Rasch Philip J. , Crutzen Paul J. , Coleman Danielle B.
Published: January 2008

Aerosols produced in the lower stratosphere can brighten the planet and counteract some of the effects of global warming. We explore scenarios in which the amount of precursors and the size of the aerosol are varied to assess their interactions with the climate system. Stratosphere‐troposphere exchange processes change in response to greenhouse gas forcing and respond to geoengineering by aerosols. Nonlinear feedbacks influence the amount of aerosol required to counteract the warming. More aerosol precursor must be injected than would be needed if stratosphere troposphere exchange processes did not change in response to greenhouse gases or aerosols. Aerosol particle size has an important role in modulating the energy budget. A prediction of aerosol size requires a much more complex representation and assumptions about the delivery mechanism beyond the scope of this study, so we explore the response when particle size is prescribed. More aerosol is required to counteract greenhouse warming if aerosol particles are as large as those seen during volcanic eruptions (compared to the smaller aerosols found in quiescent conditions) because the larger particles are less effective at scattering incoming energy, and trap some outgoing energy. About 1.5 Tg S/yr are found to balance a doubling of CO2 if the particles are small, while perhaps double that may be needed if the particles reach the size seen following eruptions.
Quantifying error in the radiative forcing of the first aerosol indirect effect
Authors: McComiskey Allison , Feingold Graham
Published: January 2008

Anthropogenic aerosol plays a major role in the Earth's radiation budget, particularly via effects on clouds. The Intergovernmental Panel on Climate Change lists the uncertainty in aerosol modification of cloud albedo as the largest unknown in the radiative forcing of climate change. Common measures of aerosol effects on clouds, Aerosol‐Cloud Interaction (ACI = −∂lnre/∂lnα, where re is drop size and α aerosol burden), cover an enormous range and, as these measures are now being used as parameterizations in global‐scale models, this has large implications for radiative forcing. We quantify the relationship between radiative forcing and changes in ACI over the range of values found in the literature. Depending on anthropogenic aerosol perturbation, radiative forcing ranges from −3 to −10 W m−2 for each 0.05 increment in ACI. Narrowing uncertainty in measures of ACI to an accuracy of 0.05 would place estimated cloud radiative forcing on a sounder footing.
Distribution of tsunami interevent times
Authors: Geist Eric L. , Parsons Tom
Published: January 2008

The distribution of tsunami interevent times is analyzed using global and site‐specific (Hilo, Hawaii) tsunami catalogs. An empirical probability density distribution is determined by binning the observed interevent times during a period in which the observation rate is approximately constant. The empirical distributions for both catalogs exhibit non‐Poissonian behavior in which there is an abundance of short interevent times compared to an exponential distribution. Two types of statistical distributions are used to model this clustering behavior: (1) long‐term clustering described by a universal scaling law, and (2) Omori law decay of aftershocks and triggered sources. The empirical and theoretical distributions all imply an increased hazard rate after a tsunami, followed by a gradual decrease with time approaching a constant hazard rate. Examination of tsunami sources suggests that many of the short interevent times are caused by triggered earthquakes, though the triggered events are not necessarily on the same fault.
Plasmoids in Saturn's magnetotail
Authors: Hill T. W. , Thomsen M. F. , Henderson M. G. , Tokar R. L. , Coates A. J. , McAndrews H. J. , Lewis G. R. , Mitchell D. G. , Jackman C. M. , Russell C. T. , Dougherty M. K. , Crary F. J. , Young D. T.
Published: January 2008

Plasmoids in Saturn's magnetotail are identified by a reversal (northward turning) of the normally southward component of the magnetic field across the tail current sheet. Three large plasmoids have been identified by the Cassini magnetometer, one near 0300 local time at a planet‐centered distance of 44 RS and two near midnight at 48–49 RS. (RS ≈ 60,300 km is Saturn's equatorial radius.) Two of these events, including in particular the 0300 event, coincided with current‐sheet crossings by the spacecraft and thus provided sufficient plasma fluxes to determine ion composition and velocity moments from Cassini Plasma Spectrometer data. The composition was largely dominated by water‐group ions, indicating an inner‐magnetosphere source. The flow was subcorotational and strongly tailward, as expected for a plasmoid. Just before the in situ detection of the 0300 plasmoid, the Magnetospheric Imaging Instrument observed an outburst of energetic neutral atoms emanating from a location midway between Saturn and Cassini, probably a signature of the reconnection event that spawned the plasmoid.
Glucose Tolerance, Lipids, and GLP‐1 Secretion in JCR:LA‐cp Rats Fed a High Protein Fiber Diet
Authors: Reimer Raylene A. , Russell James C.
Published: January 2008

Background: We have shown that individually, dietary fiber and protein increase secretion of the anorexigenic and insulinotropic hormone, glucagon‐like peptide‐1 (GLP‐1).

Objective: Our objective was to combine, in one diet, high levels of fiber and protein to maximize GLP‐1 secretion, improve glucose tolerance, and reduce weight gain.

Methods and Procedures: Lean (+/?) and obese (cp/cp) male James C Russell corpulent (JCR:LA‐cp) rats lacking a functional leptin receptor were fed one of four experimental diets (control, high protein (HP), high fiber (HF, prebiotic fiber inulin), or combination (CB)) for 3 weeks. An oral glucose tolerance test (OGTT) was performed to evaluate plasma GLP‐1, insulin and glucose. Plasma lipids and intestinal proglucagon mRNA expression were determined.

Results: Energy intake was lower with the HF diet in lean and obese rats. Weight gain did not differ between diets. Higher colonic proglucagon mRNA in lean rats fed a CB diet was associated with higher GLP‐1 secretion during OGTT. The HP diet significantly reduced plasma glucose area under the curve (AUC) during OGTT in obese rats, which reflected both an increased GLP‐1 AUC and higher fasting insulin. Diets containing inulin resulted in the lowest plasma triglyceride and total cholesterol levels.

Discussion: Overall, combining HP with HF in the diet increased GLP‐1 secretion in response to oral glucose, but did not improve glucose tolerance or lipid profiles more than the HF diet alone did. We also suggest that glycemic and insulinemic response to prebiotics differ among rat models and future research work should examine their role in improving glucose tolerance in diet‐induced vs. genetic obesity with overt hyperleptinemia.
Insurance Coverage and Incentives for Weight Loss Among Adults With Metabolic Syndrome
Authors: Arterburn David , Westbrook Emily O. , Wiese Cheryl J. , Ludman Evette J. , Grossman David C. , Fishman Paul A. , Finkelstein Eric A. , Jeffery Robert W. , Drewnowski Adam
Published: January 2008

Objective: To describe how insured adults with metabolic syndrome respond to various options for insurance coverage and financial incentives for weight management.

Methods and Procedures: Insured adults meeting the criteria for the metabolic syndrome were randomly identified through automated medical records and invited to participate in a telephone‐based survey of the acceptability of various weight management programs—with different financial incentives and insurance coverage options—in a health maintenance organization. Multivariable logistic regression models were used to test the relationship between participant characteristics and the odds of being motivated by incentives.

Results: One hundred and fifty‐three adults with the metabolic syndrome completed the survey (i.e., 79% of telephone contacts). A hypothetical increase in insurance coverage from 10 to 100% led to a threefold increase among women and a sevenfold increase among men in the proportion reporting they were “very interested” in enrolling in a weight management program within the next 30 days. Most participants (76% of women and 57% of men) supported a health plan–sponsored financial incentive program tied to weight loss, and 41% believed such a program would motivate them to lose weight. The mean financial incentive proposed for a 15‐pound weight loss was $591 (median: $125).

Discussion: Although weight loss is an effective treatment for metabolic syndrome, standard health insurance rarely covers intensive behavioral treatment. The results of this study suggest that providing full insurance coverage and financial incentives for weight management increases the interest in participating in obesity treatment programs. Further research should determine how full coverage and incentives affect participation rates, long‐term body weight changes, and costs.
Attenuation of Vascular/Neural Dysfunction in Zucker Rats Treated With Enalapril or Rosuvastatin
Authors: Oltman Christine L. , Davidson Eric P. , Coppey Lawrence J. , Kleinschmidt Travis L. , Lund Donald D. , Yorek Mark A.
Published: January 2008

Objective: Obese Zucker rats, animal model for the metabolic syndrome, develop a diabetes‐like neuropathy that is independent of hyperglycemia. The purpose of this study was to determine whether drugs used to treat cardiovascular dysfunction in metabolic syndrome also protect nerve function.

Methods and Procedures: Obese Zucker rats at 20 weeks of age were treated for 12 weeks with enalapril or rosuvastatin. Lean rats were used as controls. Vasodilation in epineurial arterioles was measured by videomicroscopy. Endoneurial blood flow (EBF) was measured by hydrogen clearance and nerve conduction velocity was measured following electrical stimulation of motor or sensory nerves.

Results: Enalapril treatment decreased serum angiotensin‐converting enzyme (ACE) activity and both drugs reduced serum cholesterol levels. In obese Zucker rats at 32 weeks of age superoxide levels were elevated in the aortas and epineurial arterioles, which were reduced by treatment with either drug. Nitrotyrosine levels were increased in epineurial arterioles and reduced with enalapril treatment. EBF was decreased and corrected by treatment with either drug. Motor nerve conduction velocity was decreased and significantly improved with enalapril treatment. Obese Zucker rats were hypoalgesic in response to a thermal stimulus and this was significantly improved with either treatment. Treatment with either enalapril or rosuvastatin significantly reversed the decrease in acetylcholine‐mediated vascular relaxation of epineurial arterioles in obese Zucker rats.

Discussion: Even though obese Zucker rats have normal glycemia vascular and neural dysfunctions develop with age and can be improved by treatment with either enalapril or rosuvastatin.
Vitamin D Status and Response to Vitamin D3 in Obese vs. Non‐obese African American Children
Authors: Rajakumar Kumaravel , Fernstrom John D. , Holick Michael F. , Janosky Janine E. , Greenspan Susan L.
Published: January 2008

Background: Serum 25‐hydroxyvitamin D (25(OH)D) is low in obese adults.

Objective: To examine serum 25(OH)D in obese (BMI >95th percentile for age) vs. non‐obese (BMI = 5th–75th percentile for age) 6–10‐year‐old African American children and compare their differences in therapeutic response to vitamin D supplementation.

Methods and Procedures: In an open label non‐randomized pre‐post comparison 21 obese (OB) and 20 non‐obese (non‐OB) subjects matched for age, sex, skin color, and pubertal maturation were treated with 400 IU of vitamin D3 daily for 1 month. Serum 25(OH)D, 1,25‐dihydroxyvitamin D (1,25(OH)2D), parathyroid hormone (PTH), leptin, and markers of bone turnover (serum bone‐specific alkaline phosphatase (BSAP), osteocalcin (OC), and urine n ‐telopeptide cross‐links of type 1 collagen (urine NTX)) were measured. Vitamin D deficiency was defined as serum 25(OH)D ≤20 ng/ml and insufficiency as 21–29 ng/ml respectively.

Results: Vitamin D deficiency occurred in 12/21 (57%) OB vs. 8/20 (40%) non‐OB at baseline (P = 0.35) and persisted in 5/21 (24%) OB vs. 2/18 (11%) non‐OB (P = 0.42) after treatment. When the cohort was stratified by the baseline levels of 25(OH)D, there were differences in the response to treatment in the obese and non‐obese cohorts.

Discussion: Vitamin D deficiency was common among OB and non‐OB preadolescent African American children, and 400 IU of vitamin D3 (2× the recommended adequate intake) daily for 1 month was inadequate to raise their blood levels of 25(OH)D to ≥30 ng/ml.
Guggulsterone Inhibits Adipocyte Differentiation and Induces Apoptosis in 3T3‐L1 Cells
Authors: Yang Jeong‐Yeh , Della‐Fera Mary Anne , Baile Clifton A.
Published: January 2008

Objective: To determine the effects of guggulsterone (GS), the active substance in guggulipid, on apoptosis, adipogenesis, and lipolysis using 3T3‐L1 cells.

Methods and Procedures: For apoptosis and lipolysis experiments, mature adipocytes were treated with GS isomers. Viability, apoptosis, and caspase 3/7 activation were quantified using MTS, enzyme‐linked immunosorbent assay (ELISA), caspase‐Glo 3/7 activity assay, respectively. The expression of cytochrome c was demonstrated by western blot. Lipolysis was quantified by measuring the release of glycerol. For adipogenesis experiments, postconfluent preadipocytes were incubated with GS isomers for up to 6 days during maturation. Adipogenesis was quantified by measuring lipid content using Nile Red dye. Western blot was also used to demonstrate the adipocyte‐specific transcription factors peroxisome proliferator–activated receptor γ2 (PPARγ2), CCAAT/enhancer binding protein α (C/EBPα), and C/EBPβ.

Results: In mature adipocytes cis‐GS decreased viability, whereas the trans‐GS isomer had little effect. Both isomers caused dose‐dependent increases in apoptosis and cis‐GS was more effective than trans‐GS in inducing apoptosis. cis‐ and trans‐GS also increased caspase‐3 activity and release of cytochrome c from mitochondria. In maturing preadipocytes, both isomers were equally effective in reducing lipid content. The adipocyte‐specific transcription factors PPARγ2, C/EBPα, and C/EBPβ were downregulated after treatment with cis‐GS during the maturation period. Furthermore, cis‐GS increased basal lipolysis of mature adipocytes, but trans‐GS had no effect.

Discussion: These results indicate that GS isomers may exert antiobesity effects by inhibiting differentiation of preadipocytes, and by inducing apoptosis and promoting lipolysis of mature adipocytes. The cis‐GS isomer was more potent than the trans‐GS isomer in inducing apoptosis and lipolysis in mature adipocytes.
A Polymorphism at the IL6ST (gp130) Locus Is Associated With Traits of the Metabolic Syndrome
Authors: Gottardo Lucia , De Cosmo Salvatore , Zhang Yuan‐Yuan , Powers Christine , Prudente Sabrina , Marescotti Maria C. , Trischitta Vincenzo , Avogaro Angelo , Doria Alessandro
Published: January 2008

The interleukin 6 signal transducer (IL6ST, also known as gp130) is a ubiquitously expressed intermediate of the interleukin‐6 signaling pathway. We investigated whether genetic variability at the IL6ST locus is involved in the modulation of metabolic traits and the etiology of the metabolic syndrome (MS). Four haplotype‐tagging single nucleotide polymorphisms were typed in two populations of non‐diabetic subjects, one from Northern Italy (Padua (PD), n = 630), the other from Southern Italy (San Giovanni Rotondo (SGR), n = 553). In the PD population, a nominally significant association was observed between fasting glucose and rs715180 (P = 0.02), rs3729960 (P = 0.02), and rs10940495 (P = 0.05), between homeostasis model assessment index (HOMAIR) and rs715180 (P = 0.04), and between triglycerides and rs3729960 (P = 0.03). In the SGR population, high‐density lipoprotein (HDL) levels were associated with rs715180 (P = 0.01), systolic blood pressure and waist circumference with rs3729960 (P = 0.005 and 0.02, respectively). The frequency of rs715180 minor allele carriers progressively decreased from individuals with no MS components to those with three or more components (P for trend = 0.006 in the two populations combined). Compared to major allele homozygotes, minor allele carriers had 40% lower odds of having at least one MS component (Odds ratio = 0.6, 95% confidence interval 0.4–0.8, P = 0.005). These findings point to IL6ST variants as possible determinants of impaired glucose metabolism and other abnormalities of MS.
Adiponectin and Metabolic Syndrome in Middle‐aged and Elderly Chinese
Authors: Wang Jing , Li Huaixing , Franco Oscar H. , Yu Zhijie , Liu Yong , Lin Xu
Published: January 2008

Objective: Hypoadiponectinemia is an important risk factor for metabolic syndrome (MetS). However, little is known about its role in the Chinese population. The aim of this study was to investigate the association between plasma adiponectin levels and MetS in middle‐aged and elderly Chinese from both urban and rural areas of northern and southern China.

Methods and Procedures: This population‐based cross‐sectional study included 3,193 subjects aged 50–70 from urban and rural areas of Beijing (northern China) and Shanghai (southern China). Plasma adiponectin concentrations were measured using a high‐throughput micro‐assay, Luminex. MetS was identified with the updated National Cholesterol Education Program Adult Treatment Panel III (NCEP ATP III) criteria.

Results: Adiponectin levels were significantly higher in female, and rural subjects than in male or urban residents (P < 0.001). The prevalence and the number of MetS components progressively increased with declined adiponectin levels (P for trend <0.001). The participants in the lowest adiponectin quartile had a significantly increased risk for acquiring MetS (odds ratio (OR) 3.38, 95% confidence interval (CI) 2.56–4.46) after adjustment for potential confounders. Subjects from Beijing or rural areas had a higher risk for MetS at the same given level of adiponectin than did their Shanghai or urban counterparts, respectively.

Discussion: Adiponectin is negatively associated with MetS in the middle‐aged and elderly Chinese independent of known confounders such as BMI, physical activity and life habits. The urban–rural and northern–southern differences in susceptibility to MetS should be taken into consideration for the early detection and prevention of MetS.
Prevalence and Associated Factors of Overweight and Obesity in a Chinese Rural Population
Authors: Zhang Xingang , Sun Zhaoqing , Zhang Xinzhong , Zheng Liqiang , Liu Shuangshuang , Xu Changlu , Li Jiajin , Zhao Fenfen , Li Jue , Hu Dayi , Sun Yingxian
Published: January 2008

Background: Overweight and obesity are now considered as a serious health problem, and a very important risk factor for many diseases.

Objective: This study was designed to investigate the epidemiologic features of overweight and obesity among rural adults in China.

Method and Procedures: A cross‐sectional survey was conducted during 2004–2005, using a multistage cluster sampling method to select a representative sample in Fuxin county, Liaoning province, China. A total of 29,970 adults, aged ≥35 years, were examined. At baseline, lifestyle and other factors were obtained. Overweight and obesity were defined according to the classification by the World Health Organization.

Results: Overall, the prevalence of overweight was 18.6%; 15.1% in men and 22.1% in women. The prevalence of obesity was 1.7%; 1.2% in men and 2.2% in women. Multivariable logistic regression revealed certain risk factors of obesity that included being a women, Mongolian nationality and education status of over junior high school level. Moderate physical activity alone was shown as protective factor.

Discussion: Although the prevalence of obesity was low, overweight was relatively high in the Chinese rural population, especially in adult women. Gender, diet, physical activity, education levels, and ethnicity were associated with the prevalence of these health conditions.
Physical Activity Patterns in the National Weight Control Registry
Authors: Catenacci Victoria A. , Ogden Lorraine G. , Stuht Jennifer , Phelan Suzanne , Wing Rena R. , Hill James O. , Wyatt Holly R.
Published: January 2008

Objective: The National Weight Control Registry (NWCR) was established in 1993 to examine the characteristics of those who are successful at weight loss: individuals maintaining a 13.6‐kg weight loss for >1 year. The size of the registry has increased substantially since the early descriptions of this group a decade ago. The purpose of this study was to describe in detail the weekly physical activity habits of NWCR members, to examine the relationship between amount of activity and demographic characteristics, and to determine if changes in activity parameters have occurred over time.

Methods and Procedures: Participants were 887 men and 2,796 women who enrolled in the NWCR between 1993 and 2004. Physical activity was evaluated at registry entry using the Paffenbarger Physical Activity Questionnaire.

Results: NWCR entrants report an average of 2,621 ± 2,252 kcal/week in physical activity. There is considerable variability in the amount of activity reported: 25.3% report <1,000 kcal/week and 34.9% report >3,000 kcal/week. Activity level on registry entry is related to the magnitude but not the duration of weight loss. The amount of activity reported by men has decreased over time while no significant change was observed in women. Changes in the types of activities most frequently reported were also observed.

Discussion: Overall, NWCR participants are an extremely physically active group. However, the amount of activity reported is highly variable, making it difficult to develop a single recommendation for the optimum amount of physical activity for weight loss maintenance. A better understanding of individual‐specific determinants of how much activity is required for weight loss maintenance ought to be a high research priority.
Testing of a scanning adiabatic calorimeter with Joule effect heating of the sample
Authors: Barreiro-Rodríguez G. , Yáñez-Limón J. M. , Contreras-Servin C. A. , Herrera-Gomez A.
Published: January 2008

We evaluated a scanning adiabatic resistive calorimeter (SARC) developed to measure the specific enthalpy of viscous and gel-type materials. The sample is heated employing the Joule effect. The cell is constituted by a cylindrical jacket and two pistons, and the sample is contained inside the jacket between the two pistons. The upper piston can slide to allow for thermal expansion and to keep the pressure constant. The pistons also function as electrodes for the sample. While the sample is heated through the Joule effect, the electrodes and the jacket are independently heated to the same temperature of the sample using automatic control. This minimizes the heat transport between the sample and its surroundings. The energy to the sample is supplied by applying to the electrodes an ac voltage in the kilohertz range, establishing a current in the sample and inducing electric dissipation. This energy can be measured with enough exactitude to determine the heat capacity. This apparatus also allows for the quantification of the thermal conductivity by reproducing the evolution of the temperature as heat is introduced only to one of the pistons. To this end, the system was modeled using finite element calculations. This dual capability proved to be very valuable for correction in the determination of the specific enthalpy. The performance of the SARC was evaluated by comparing the heat capacity results to those obtained by differential scanning calorimetry measurements using a commercial apparatus. The analyzed samples were zeolite, bauxite, hematite, bentonite, rice flour, corn flour, and potato starch.
Contribution of inter- and intramolecular energy transfers to heat conduction in liquids
Authors: Torii Daichi , Nakano Takeo , Ohara Taku
Published: January 2008

The molecular dynamics expression of heat flux, originally derived by Irving and Kirkwood [J. Chem. Phys. 18, 817 (1950)] for pairwise potentials, is generalized in this paper for systems with many-body potentials. The original formula consists of a kinetic part and a potential part, and the latter term is found in the present study to be expressible as a summation of contributions from all the many-body potentials defined in the system. The energy transfer among a set of sites for which a many-body potential is defined is discussed and evaluated by the rate of increase in the kinetic energy of each site due to the potential, and its accumulation over all the potentials in the system is shown to make up the potential part of the generalized expression. A molecular dynamics simulation for liquid n-octane was performed to demonstrate the applicability of the new expression obtained in this study to measure the heat flux and to elucidate the contributions of inter- and intramolecular potentials to heat conduction.
Local-density approximation for orbital densities applied to the self-interaction correction
Authors: Umezawa Naoto
Published: January 2008

A simple approximation to the functional derivative of Perdew-Zunger-type self-interaction-corrected local-spin density functional is suggested. In this approach, the orbital density ∣ϕiσ(r)∣2 is regarded as a functional of the local electron density ∣ϕiσ(r)∣2=niσ(nσ(r)) so as to enable a functional derivative of niσ(nσ(r)) with respect to nσ(r). Our computational results show that this approximation gives fairly good estimates of the total energy, the ionization potential, and the electron affinity for atoms. Comparative studies of this method with the averaged-density approximation and the global averaging method for the self-interaction correction are made.
Infrared spectra of CO2-doped He4 clusters, HeN4–CO2, with N=1–60
Authors: McKellar A. R. W.
Published: January 2008

High resolution spectra of HeN4–CO2 clusters are studied in the region of the CO2 ν3 fundamental band (∼2300cm−1). The clusters are produced in a pulsed supersonic jet expansion from a cooled nozzle source and probed by direct absorption using a tunable diode laser operating in a rapid-scan mode. Four carbon dioxide isotopes (O16C12O16, O16C13O16, O18C13O18, and O16C13O18) are used to support the analysis, and because additional rotational transitions are allowed for the asymmetric one (O16C13O18). Resolved R(0) (J=1←0) rotation-vibration transitions are observed for clusters up to N=60. A detailed rotational analysis is possible up to N≈20 and, with some assumptions, to N≈37 and beyond. The derived rotational constants (B values) vary smoothly with N and show evidence for broad oscillations similar to those already reported for HeN–OCS and HeN–N2O. Possible indications of a disruption are observed in the J=2 levels of larger clusters (N>22) which could be caused by interactions with a “dark” helium cluster modes.
A general electromagnetic field-circuit coupling method based on time-stepping finite element analysis for performance analysis of pulse-width modulated switching converters considering hysteresis effects
Authors: Chen Jiaxin , Guo Youguang , Zhu Jian Guo , Lin Zhi Wei
Published: January 2008

Considering the special characteristics existing in the pulse-width modulated (PWM) switching converter, a general method for the time-stepping finite element analysis based electromagnetic field coupling with its feeding circuit used in the analysis of PWM switching converter considering hysteresis effects is introduced in this paper. Comparing with the electromagnetic field-circuit indirect coupling method (ICM), the proposed method has overcome the drawback that the ICM cannot take the hysteresis effects into account. Compared with the electromagnetic field-circuit direct coupling method (DCM), the proposed method has the similar accuracy but higher efficiency. Furthermore, like the ICM, the proposed method also divides the system with higher state dimensions produced by the DCM into two subsystems with lower state dimensions; this may reduce the algorithm convergence problem which often happens in high dimensional systems.
A tubular flux-switching permanent magnet machine
Authors: Wang J. , Wang W. , Clark R. , Atallah K. , Howe D.
Published: January 2008

The paper describes a novel tubular, three-phase permanent magnet brushless machine, which combines salient features from both switched reluctance and permanent magnet machine technologies. It has no end windings and zero net radial force and offers a high power density and peak force capability, as well as the potential for low manufacturing cost. It is, therefore, eminently suitable for a variety of applications, ranging from free-piston energy converters to active vehicle suspensions.
Temperature dependence of the magnetostriction and magnetoelastic coupling in Fe100−xAlx (x=14.1,16.6,21.5,26.3) and Fe50Co50
Authors: Clark A. E. , Restorff J. B. , Wun–Fogle M. , Wu D. , Lograsso T. A.
Published: January 2008

In this paper, we report magnetostriction measurements, (λ100) on Fe-rich Fe–Al alloys and Fe50Co50 as functions of temperature from 77K to room temperature (RT). From these measurements and elastic constant (c′) measurements, the tetragonal magnetoelastic coupling constants (b1’s) were calculated. Significant differences were found between our RT measurements and earlier magnetostriction measurements for the higher Al concentration alloys (16.6%, 21.5%, 26.3% Al) and the Fe50Co50 alloy. Reminiscent of the temperature dependence of λ100 for pure Fe, magnetostriction changes with temperature are minimal for Fe–Al alloys having the disordered bcc (A2) structure (x<19% Al). In contrast, the alloy possessing the ordered (D03) structure shows an anomalous decrease in magnetostriction in λ100 with decreasing temperature. For the Fe–Al alloy system, the magnetoelastic coupling constant, ∣b1∣, exhibits a peak at room temperature maximizing at 16.6% Al with a value of 12.3MJ∕m3. For Fe50Co50, ∣b1∣ was calculated to be ∼34MJ∕m3 at room temperature.
Observation of field-induced domain wall propagation in magnetic nanowires by magnetic transmission x-ray microscopy
Authors: Bryan M. T. , Fry P. W. , Fischer P. J. , Allwood D. A.
Published: January 2008

Magnetic transmission x-ray microscopy (M-TXM) is used to image domain walls in magnetic ring structures formed by a 300nm wide, 24nm thick Ni81Fe19 nanowire. Both transverse- and vortex-type domain walls are observed after application of different field sequences. Domain walls can be observed by comparing images obtained from opposite field sequences or else domain wall propagation observed by comparing successive images in a particular field sequence. This demonstrates the potential use of M-TXM in developing and understanding planar magnetic nanowire behavior.
Comparative micro-Raman spectroscopy study of tellurium-filled double-walled carbon nanotubes
Authors: Sendova Mariana , Flahaut Emmanuel
Published: January 2008

Tellurium-filled double-walled carbon nanotubes (Te@DWNTs) have been studied by Raman spectroscopy in the temperature interval from 300to700K employing 785nm excitation wavelength, and their spectra have been compared to those of pristine double-walled carbon nanotubes (DWNTs). The DWNTs were synthesized by catalytic chemical vapor deposition. Assignment of the radial breathing modes and the tangential modes was done based on the one dimensional electronic energy band structure of carbon nanotubes. The tangential mode components of Te@DWNT are downshifted compared to those of pristine DWNT consistent with the proposed weakening of the carbon-carbon bond due to the introduced van der Waals interaction of the Te atoms with the DWNT. It was established that Te@DWNT can be unambiguously identified by the 30% temperature coefficient decrease of the G′-band position.
Nonlinear current-voltage characteristics of oxygen-deficient La0.67Ca0.33MnO3−y films
Authors: Liu S. J. , Juang J. Y. , Lin J.-Y. , Wu K. H. , Uen T. M. , Gou Y. S.
Published: January 2008

Two different types of nonlinear current-voltage characteristics are observed in oxygen-deficient La0.67Ca0.33MnO3−y (LCMO) films at temperatures below the insulator-metal transition. The paraboliclike dynamic conductance G(V), defined as dI/dV, curves near the zero bias observed in highly oxygen-deficient LCMO films implies the contribution from the spin-dependent tunneling transport between ferromagnetic clusters, with magnetic-disordered regions serving as tunneling barriers. On the other hand, for the slightly oxygen-deficient LCMO films, dips around the zero bias were observed in nonlinear G(V) curves and have been attributed to spin-flip scattering, with oxygen vacancies serving as scattering centers.
NMR study of liquid to solid transition in a glass forming metallic system
Authors: Li Lilong , Wu Yue
Published: January 2008

Quadrupolar spin-lattice relaxation effect was used to study the temperature dependence of the correlation of electric field gradient (EFG) observed by Cu63 and Cu65 NMR in the liquid and supercooled liquid states of Pd43Cu27Ni10P20 metallic glass forming system. The correlation time of EFG was shown to have a dramatic temperature dependence that cannot be accounted for by available theory. Analyzed in the context of mode coupling theory (MCT), it is shown that the correlation time of EFG follows the scaling equation of MCT and reveals a Tc, the critical temperature of MCT, at 700K. Other NMR techniques such as chemical exchange line narrowing and stimulated echo pulse sequences were used to study motion of P31 at lower temperatures. Combined together, these techniques cover the whole range of liquid to solid transition. By comparing the NMR results with data obtained by other techniques, a decoupling of motion for different types of atoms is revealed starting from Tc and below. This essentially demonstrates a transition from liquidlike to solidlike motion at Tc as predicted by MCT.
Magnetic and transport and structure properties of the room temperature ferromagneto Sr1−xHoxCoO3−δ
Authors: Balamurugan S. , Yamaura K. , Asthana A. , Ubaldini A. , Matsui Y. , Takayama-Muromachi E.
Published: January 2008

The perovskite Sr1−xHoxCoO3−δ shows room temperature ferromagnetism (Tc∼335K) in a severely limited composition range 0.2⩽x⩽0.25. The formal Co valence is almost constant at +3 regardless of the Ho concentration (x⩾0.2); thus, the high-spin state or the intermediate spin state of 3d6 Co should be mainly responsible for the magnetism. The ferromagnetism was found to accompany the formation of a superstructure 2ap×2ap×4ap (ap denotes a cubic perovskite cell). Besides, an additional superstructure 4(2ap)×4(2ap)×(4ap) was found at x=0.225, where the ferromagnetic volume in magnetic susceptibility was largest. The data suggest that the formation of the multiple superstructures probably plays a key role to establish the peculiar ferromagnetism.
Electronic properties of single crystalline UNi0.39Rh0.61Al
Authors: El-Khatib S. , Alsmadi A. M. , Correa V. , Andreev A. V. , Lacerda A. , Nasreen F. , Nakotte H.
Published: January 2008

U(Ni,Rh)Al alloys crystallize in the hexagonal ZrNiAl structure. Here, we report on measurements on a single crystalline member of this series, namely, UNi0.39Rh0.61Al. Similar to other members of this series, this compound exhibits highly anisotropic properties with the easy-magnetization direction along the c-axis. We report in the results of electrical resistance, magnetoresistance, and thermal expansion as a function of temperature (2–300K) and applied magnetic field (0–18T). The results provide strong evidence for antiferromagnetic ordering at TN⩽15K followed by a ferromagneticlike (ferro—or ferrimagnetic) transition around 7K (we use the term “ferromagneticlike” because, based on our bulk data, we cannot exclude canted moments with antiferromagnetic components or ferromagnetic order of two different moments). A magnetic B-T phase diagram for UNi0.39Rh0.61Al is proposed.
Spin transitions of Co ions in RCoO3 (R=Gd,Tb) investigated by measuring the electric field gradient at R and Co sites
Authors: Carbonari A. W. , Cavalcante F. H. M. , Malavasi R. F. L. , Cabrera-Pasca G. A. , Mestnik-Filho J. , Saxena R. N.
Published: January 2008

Hyperfine interactions in perovskite-structure RCoO3 (R=Gd,Tb) compounds have been measured by perturbed angular correlation technique using Cd111 and Ta181 nuclear probes. The electric quadrupole interactions at Cd111 show two different sites, assigned to probe substituting Gd or Tb and Co atoms. The temperature dependence of quadrupole frequencies shows discontinuities which have been interpreted as thermally activated spin-state transitions from low-spin ground state configuration to the intermediate-spin (IS) state and from IS state to high-spin state of Co3+ ion. For Ta181 only one major interaction was observed, which was assigned to probe at Co sites. Indication of a Jahn-Teller distortion, which stabilizes the intermediate-spin state with orbital ordering, is also pointed out.
Analysis methodology of movable emittance-meter measurements for low energy electron beams
Authors: Mostacci A. , Bacci A. , Boscolo M. , Chiadroni E. , Cianchi A. , Filippetto D. , Migliorati M. , Musumeci P. , Ronsivalle C. , Rossi A. R.
Published: January 2008

The design of photoinjectors for modern free electron laser linac relies heavily on particular beam behavior in the few meters after the gun. To experimentally characterize it a movable emittance meter was proposed and built [L. Catani et al., Rev. Sci. Instrum. 77, 093301 (2006)] based on the beam slicing technique. This paper addresses all the aspects of analysis of the data acquired with the emittance meter and common to any slit based emittance measurement for low energy beams.
Dissipative cryogenic filters with zero dc resistance
Authors: Bluhm Hendrik , Moler Kathryn A.
Published: January 2008

The authors designed, implemented, and tested cryogenic rf filters with zero dc resistance, based on wires with a superconducting core inside a resistive sheath. The superconducting core allows low frequency currents to pass with negligible dissipation. Signals above the cutoff frequency are dissipated in the resistive part due to their small skin depth. The filters consist of twisted wire pairs shielded with copper tape. Above approximately 1GHz, the attenuation is exponential in ω, as typical for skin depth based rf filters. By using additional capacitors of 10nF per line, an attenuation of at least 45dB above 10MHz can be obtained. Thus, one single filter stage kept at mixing chamber temperature in a dilution refrigerator is sufficient to attenuate room temperature black body radiation to levels corresponding to 10mK above about 10MHz.
Sparsity enhancement for blind deconvolution of ultrasonic signals in nondestructive testing application
Authors: Wei Liang , Hua-ming Lei , Pei-wen Que
Published: January 2008

The received signal in ultrasonic pulse-echo inspection can be modeled as a convolution between an impulse response and the reflection sequence, which is the impulse characteristic of the inspected object. Deconvolution aims at approximately inverting this process to improve the time resolution so that the overlap between echoes from closely spaced reflectors becomes small. This paper presents a modified minimum entropy blind deconvolution algorithm for deconvolving ultrasonic signals. Enhancement of the resolution is achieved by using the presented method. In addition, the presented approach will, in many cases, lead to a faster computation. A nonlinear function is the key point to the efficiency of the modified blind deconvolution algorithm, which is used to increase the sparsity of the iteration output and to decrease the influence of the added noise by replacing each iteration output by output of the nonlinear function. Simulations showed the efficiency of the modification as compared with minimum entropy deconvolution when deconvolving synthetic ultrasonic signals. Experimental results using real ultrasonic data evaluated further that the exact solution consistently yields good performance. The thickness of a thin steel sample can be calculated by the modified blind deconvolution filter with a reasonable accuracy.
Expanding roles of plant aquaporins in plasma membranes and cell organelles
Authors: Katsuhara Maki , Hanba Yuko T. , Shiratake Katsuhiro , Maeshima Masayoshi
Published: January 2008

Aquaporins facilitate water transport across biomembranes in a manner dependent on osmotic pressure and water-potential gradient. The discovery of aquaporins has facilitated research on intracellular and whole-plant water transport at the molecular level. Aquaporins belong to a ubiquitous family of membrane intrinsic proteins (MIP). Plants have four subfamilies: plasma-membrane intrinsic protein (PIP), tonoplast intrinsic protein (TIP), nodulin 26-like intrinsic protein (NIP), and small basic intrinsic protein (SIP). Recent research has revealed a diversity of plant aquaporins, especially their physiological functions and intracellular localisation. A few PIP members have been reported to be involved in carbon dioxide permeability of cells. Newly identified transport substrates for NIP members of rice and Arabidopsis thaliana have been demonstrated to transport silicon and boron, respectively. Ammonia, glycerol, and hydrogen peroxide have been identified as substrates for plant aquaporins. The intracellular localisation of plant aquaporins is diverse; for example, SIP members are localised on the ER membrane. There has been much progress in the research on the functional regulation of water channel activity of PIP members including phosphorylation, formation of hetero-oligomer, and protonation of histidine residues under acidic condition. This review provides a broad overview of the range of potential aquaporins, which are now believed to participate in the transport of several small molecules in various membrane systems in model plants, crops, flowers and fruits.
Dehydrins in Lupinus albus: pattern of protein accumulation in response to drought
Authors: Pinheiro Carla , Cruz de Carvalho Maria H. , Bartels Dorothea , Ricardo Cândido Pinto , Chaves M. Manuela
Published: January 2008

Dehydrins (DHNs) are proteins that accumulate abundantly in various plant tissues in response to environmental stresses and during seed maturation, possibly assisting cells in tolerating dehydration. White lupins (Lupinus albus L.) are able to withstand periods of severe water deficit (WD) and previous work suggested that the stem plays a central role as a survival structure. To investigate DHNs involvement in this strategy, we studied tissue specific protein accumulation of a RAB16-like DHN in lupin during a progressive WD and early recovery. Differences were found between leaves, stems and roots. In leaves and roots, the accumulation of the RAB16-like DHN was independent of the water status whereas in the stem (cortex and stele), DHNs were only detected under severe plant WD (stele relative water content, RWC, reduction of 6–7% and cortex RWC reduction of 20%). DHN mRNA analysis by RT–PCR, showed the presence of one DHN mRNA regardless of the tissue or the plant water status.
Short-term 15N uptake kinetics and nitrogen nutrition of bryophytes in a lowland rainforest, Costa Rica
Authors: Wanek Wolfgang , Pörtl Katja
Published: January 2008

Though bryophytes can markedly affect the hydrological and biogeochemical cycles of tropical rainforests, virtually nothing is known on their nutritional requirements. Here, short-term 15N uptake kinetics of NO3–, NH4+ and glycine were studied in nine species of bryophytes in a lowland wet tropical forest, Costa Rica. Net uptake of all three N forms obeyed to saturation (Michaelis-Menten) kinetics between 1 and 500 µmol L–1. Mean Km (Vmax) values ranged between 21 µm (6.6 µmol g–1 DW h–1, nitrate), 94 µm (43.5 µmol g–1 DW h–1, ammonium) and 126 µm (37.6 µmol g–1 DW h–1, glycine). No significant differences were evident between epiphyllous and epiphytic bryophytes. Concentrations of nitrogenous solutes of external sources ranged between 1.7 and 35.9 µm. External nitrogen concentrations and kinetic constants of the bryophyte species allowed estimation of net uptake rates in the field. The mean uptake rates were 1.8 µmol g–1 DW h–1 for nitrate, 3.6 µmol g–1 DW h–1 for ammonium, and 3.4 µmol g–1 DW h–1 for glycine, indicating that amino acids significantly contribute to bryophyte nutrition.
A mutant ankyrin protein kinase from Medicago sativa affects Arabidopsis adventitious roots
Authors: Chinchilla Delphine , Frugier Florian , Raices Marcela , Merchan Francisco , Giammaria Veronica , Gargantini Pablo , Gonzalez-Rizzo Silvina , Crespi Martin , Ulloa Rita
Published: January 2008

A family of plant kinases containing ankyrin-repeats, the Ankyrin-Protein Kinases (APKs), shows structural resemblance to mammalian Integrin-Linked Kinases (ILKs), key regulators of mammalian cell adhesion. MsAPK1 expression is induced by osmotic stress in roots of Medicago sativa (L.) plants. The Escherichia coli-purified MsAPK1 could only phosphorylate tubulin among a variety of substrates and the enzymatic activity was strictly dependent on Mn2+. MsAPK1 is highly related to two APK genes in Arabidopsis thaliana (L.), AtAPK1 and AtAPK2. Promoter-GUS fusions assays revealed that the Arabidopsis APK genes show distinct expression patterns in roots and hypocotyls. Although Medicago truncatula (L.) plants affected in MsAPK1 expression could not be obtained using in vitro regeneration, A. thaliana plants expressing MsAPK1 or a mutant MsAPK1 protein, in which the conserved aspartate 315 of the kinase catalytic domain was replaced by asparagines (DN-lines), developed normally. The DN mutant lines showed increased capacity to develop adventitious roots when compared with control or MsAPK1-expressing plants. APK-mediated signalling may therefore link perception of external abiotic signals and the microtubule cytoskeleton, and influence adventitious root development.
Evaluating a seasonal, sex-specific size-structured stock assessment model for the American lobster, Homarus americanus
Authors: Kanaiwa Minoru , Chen Yong , Wilson Carl
Published: January 2008

Many models of different complexities are developed for fisheries stock assessment, and yet few have been rigorously evaluated for their performance in capturing fisheries population dynamics. This causes confusion about when a model should be used or not in assessing fisheries resources. This is especially true for models with complex structures. The present study evaluated the performance of a seasonal, sex-specific and size-structured stock assessment model with respect to the temporal pattern of recruitment, observation errors associated with input data, process errors and violation of model assumptions for the American lobster Homarus americanus. Using an individual-based lobster simulator, a series of lobster fisheries with different characteristics were simulated and the model was applied to the simulated data to estimate key fisheries parameters. Estimated values were then compared with the true values in the simulated fisheries to evaluate the model’s ability to capture the temporal trend in stock abundance, biomass and recruitment, and to identify factors that might result in model failure. Results show that this newly developed lobster stock assessment model performs well in capturing the dynamics of the lobster population under a wide range of conditions. Temporal trends in natural mortality and biased estimates of growth parameters posed the most serious problems. The present study shows the importance of model evaluation.