bluuebunny/crossref_metadata_2025 huggingface dataset:
Twenty-six-year monitoring of water masers
Authors: Rudnitskij G. M. , Pashchenko M. I. , Esipov V. F. , Samodurov V. A. , Subaev I. A. , Tolmachev A. M. , Lekht E. E.
Published: January 2008

Since 1980 variability of a sample of H2O maser sources has been monitored on the 22-metre radio telescope in Pushchino, Russia. The interval between successive observational sessions is 1–2 months. The sample includes 125 maser sources in star-forming regions (SFR) and late-type variable stars. Twenty-six-year time series of H2O line profiles have detected flares and velocity drift of spectral features. Very fast variations in the H2O maser flux (Δt ≲ 1 hour) have been detected in several SFR sources, in particular, W33B. Variations of circumstellar H2O masers in late-type stars correlate with visual light curves with a time lag of 0.3-0.4P (P is the star's period). Exceptionally strong H2O maser flares were recorded in SFR sources (Sgr B2 and others) and in the stars W Hya, R Cas and U Ori. Models for H2O maser variability are reviewed. For stellar masers shock-wave excitation of H2O line variability is discussed.
Masers as probes of massive star formation in the nuclear disk
Authors: Yusef-Zadeh F. , Arendt R. G. , Heinke C. O. , Hinz J. L. , Hewitt J. W. , Pratap P. , Ramirez S. V. , Rieke G. H. , Roberts D. A. , Stolovy S. R. , Wardle M. , Whitney B. A.
Published: January 2008

OH(1720 MHz) and methanol masers are now recognized to be excellent probes of the interactions of supernova remnants with molecular clouds and tracers of massive star formation, respectively. To better understand the nature of star formation activity in the central region of the Galaxy, we have used these two classes of masers combined with the IRAC and MIPS data to study prominent sites of ongoing star formation in the nuclear disk. The nuclear disk is characterized by massive GMCs with elevated gas temperatures, compared to their dust temperatures. We note an association between methanol masers and a class of mid-infrared “green sources”. These highly embedded YSOs show enhanced 4.5μm emission due to excited molecular lines.

The distribution of methanol masers and supernova remnants suggest a low efficiency of star formation (with the exception of Sgr B2), which we believe is due to an enhanced flux of cosmic ray electrons impacting molecular clouds in the nuclear disk. We also highlight the importance of cosmic rays in their ability to heat molecular clouds, and thus increase the gas temperature.
The distance to G59.7+0.1
Authors: Xu Y. , Reid M. J. , Menten K. M. , Brunthaler A. , Zheng X. W. , Moscadelli L.
Published: January 2008

We have measured the distance to the high-mass star-forming region G59.7+0.1, which harbors the far-infra-red source IRAS 19410+2336. The distance is 2.20 ± 0.11 kpc and was determined by triangulation using Very Long Baseline Array (VLBA) observations of 12.2 GHz methanol masers phase-referenced to two compact extragalactic radio sources.
Masers in AGN environments
Authors: Greenhill L. J.
Published: January 2008

Galactic nuclei are well known sources of OH and H2O maser emission. It appears that intense star formation in ultra-luminous infrared galaxies drives most OH sources. In contrast, nuclear activity appears to drive most H2O sources. When H2O emission originates in accretion disk structures, constrained geometry and dynamics enable robust interpretation of spectroscopic and imaging data. The principal science includes study of AGN geometry at parsec and sub-parsec radii and measurement of geometric distances in the Hubble Flow. New high accuracy estimates of the “Hubble constant, H○” obtained from maser distances may enable new substantively improved constraints on fundamental cosmological parameters (e.g., dark energy).
An atlas of extragalactic water vapor masers
Authors: Braatz J. , Kondratko P. , Greenhill L. , Condon J. , Henkel C. , Gugliucci N. , Hao L. , Reid M. , Moran J. , Lo K.-Y.
Published: January 2008

We present an atlas of extragalactic water vapor masers. As of 2007, one hundred galaxies have been detected as sources of water vapor maser emission, two thirds of them discovered since 2003. Extragalactic water masers fall in at least three categories: those associated with nuclear jets or winds, those in starbursts or star-forming regions, and those in AGN accretion disks. While all maser systems offer the possibility of unique investigations into their physical environments, it is the disk masers that have been most aggressively sought because of their potential for use as precision distance indicators. Type 2 Seyfert and LINER galaxies are hosts to such disk masers. Insingle-dish spectra, disk masers are often revealed by the presence of high-velocity emission features (defined roughly by having anomalous velocities in excess of 200 km s−1). About one third of the extragalactic water masers detected to date show evidence of disk origin. Only a few galaxies are currently identified as jet-type or star-forming type. The remaining systems show only a few narrow doppler components, usually near the systemic velocity, and are difficult to categorize. These unclassified systems are detected toward AGNs and are also possibly associated with disks or winds near the nucleus. Detection rates in large maser surveys are typically 5% or less, but the observing efficiency and sensitivity of the Green Bank Telescope (GBT) allow for short integration times (typically 10 minutes to detect a narrow 30 mJy line) so many galaxies can be searched. Recently, GBT surveys targeting type 2 Seyfert galaxies identified by the SDSS have been the most productive, identifying 17 systems in surveys observed during 2006.
Masers in starburst galaxies
Authors: Darling Jeremy
Published: January 2008

Masers in starburst galaxies are outstanding probes of a range of phenomena related to galaxy and black hole evolution, and offer unique high brightness temperature illumination that can be used to probe small scales in the host galaxy and in our own. But we require a deeper understanding of the galaxy-scale maser phenomenon if we wish to employ starburst galaxy masers as probes using the next generation of radio telescopes. This review summarizes what is known about the different flavors of masers in starburst galaxies and the setting and structure of OH megamasers. The question of which galaxies produce megamasers and which do not is critical to our understanding of the megamaser phenomenon, and recent studies of HCN and H2CO are particularly instructive. Constraints on the lifetime of OH megamasers and the predictability of OH megamaser line properties are critical issues to address in the near future. It is also time to begin the next wave of OH megamaser surveys at higher redshifts and to finally employ them as probes of starbursts, massive black holes, galaxy evolution, and intervening media.
OH main line masers in the M 82 starburst
Authors: Argo M. K. , Pedlar A. , Muxlow T. W. B. , Beswick R. J.
Published: January 2008

A study of the distribution of OH gas in the central region of the nearby active starburst galaxy M82 has confirmed two previously known bright masers and revealed several new main line masers. Three of these are seen only at 1665 MHz, one is detected only at 1667 MHz, while the rest are detected in both lines. Observations covering both the 1665 and 1667 MHz lines, conducted with both the Very Large Array (VLA) and the Multi-Element Radio Linked Interferometer Network (MERLIN), have been used to accurately measure the positions and velocities of these features. This has allowed a comparison with catalogued continuum features in the starburst such as HII regions and supernova remnants, as well as known water and satellite line OH masers. Most of the main line masers appear to be associated with known HII regions although the two detected only at 1665 MHz are seen along the same line of sight as known supernova remnants.
Exciting maser science with new instruments – the promise of the EVLA
Authors: Menten Karl M.
Published: January 2008

In the near future, the Expanded Very Large Array (EVLA) will allow surveys for maser sources with unprecedented sensitivity, spectral coverage and spectroscopic capabilities. In particular, comprehensive surveys for many maser species with simultaneous sensitive continuum imaging and absorption studies will give a comprehensive radio picture of star formation in the Galactic plane and elsewhere. Very efficient EVLA surveys for H2O megamasers in Active Galacic Nuclei will be possible to practically arbitrary redshifts.

EVLA and Atacama Large Millimeter Array (ALMA) studies of H2O and SiO masers will serve as high resolution probes of the innermost envelopes of oxygen-rich evolved stars and HCN masers of carbon-rich stars.

Farther in the future, the Square Kilometer Array (SKA) promises the detection of OH gigamasers at all conceivable redshifts and maser astrometry with unprecedented accuracy.
ALMA's view of maser emission
Authors: Wootten Alwyn
Published: January 2008

ALMA, the Atacama Large Millimeter/submillimeter Array, provides a large collecting area at a location on a high dry site, endowing it with unparalleled potential for sensitive spectral line observations. Its wide frequency coverage, superb receivers and flexible backend will ensure that that potential is met. Although in the Southern Hemisphere, its tropical latitude ensures good coverage of the northern sky. Since the last meeting on astrophysical masers, the ALMA team has substantially enhanced its capability for line observations. Japan's entry into ALMA has provided increased sensitivity with the addition of the 16 antennas of the Atacama Compact Array, equivalent to eight additional 12m telescopes. The first four cartridges for the baseline ALMA receiver packages (to be augmented by three other bands owing to Japanese participation) have been accepted, with performance above the already-challenging specifications. At first light, ALMA will offer nearly complete frequency coverage of the millimeter and submillimeter spectral windows, ensuring coverage of a variety of masering transitions. ALMA's flexibility as a spectrometer has increased with the enhancement of the baseline correlator with tunable filter banks, and with the addition of a separate correlator for the ACA. As an example of the increased flexibility, ALMA is now capable of multi-spectral-region and multi-resolution modes. With the former, one might observe e.g. four separate transitions anywhere within one of four 2 GHz bands with a high resolution bandwidth. With the latter, one might simultaneously observe with low spectral resolution over a wide bandwidth and with high spectral resolution over a narrow bandwidth. Thus, one could simultaneously cover an extremely broad velocity range while providing high spectral resolution of groups of lines within that range. Several science examples will be presented illustrating ALMA's potential for transforming the millimeter and submillimeter study of masers.
Mild Hypothermia Improves Transient Gene Expression Yields Several Fold in Chinese Hamster Ovary Cells
Authors: Wulhfard Sarah , Tissot Stéphanie , Bouchet Sophie , Cevey Jean , de Jesus Maria , Hacker David L. , Wurm Florian M.
Published: January 2008

Large‐scale transient gene expression (TGE) in mammalian cells is a rapid method to generate recombinant proteins, but the volumetric productivity for secreted proteins is still more than an order of magnitude lower than the yields typically achieved with recombinant cell lines. Here transient recombinant protein production in Chinese hamster ovary cells transfected with linear 25 kDa polyethylenimine was significantly enhanced by incubation of the cells at temperatures ranging from 29 to 33 °C after DNA delivery. With this approach, transient recombinant antibody yields of 60–80 mg/L were achieved within 6 days of transfection. The increase in TGE correlated with the accumulation of cells in the G1 phase of the cell cycle, increased cell size, higher cell viability, higher steady‐state levels of transgene mRNA, reduced consumption of nutrients, and decreased accumulation of waste products. The enhancement of TGE was not vector‐dependent, but the presence of the woodchuck hepatitis virus post‐transcriptional regulatory element in the 3′ untranslated region of the transgene mRNA increased transient recombinant antibody expression more than 3‐fold at 31 °C as compared to expression at 37 °C. The yields achieved by the low‐temperature enhancement of TGE in CHO cells makes this technology feasible for the rapid production of gram amounts of secreted recombinant proteins at large scale (up to 100 L).
Regional and seasonal variations of the Twomey indirect effect as observed by the ATSR‐2 satellite instrument
Authors: Bulgin Claire E. , Palmer Paul I. , Thomas Gareth E. , Arnold Christopher P. G. , Campmany Elies , Carboni Elisa , Grainger Roy G. , Poulsen Caroline , Siddans Richard , Lawrence Bryan N.
Published: January 2008

We use satellite observations of aerosol optical depth τa and cloud effective radius re from the ATSR‐2 instrument in 1997 to investigate the Twomey indirect effect (IE, −∂ ln re/∂ ln τa) in regions of continental outflow. We generally find a negative correlation between τa and re, with the strongest inverse relationships downwind of Africa. North American and eastern Asian continental outflow exhibits a strong seasonal dependence, as expected. Global values for IE range from 0.10 to 0.16, consistent with theoretical predictions. Downwind of Africa, we find that the IE is unphysically high but robust (r = −0.85) during JJA associated with high aerosol loading, and attribute this tentatively to the Twomey hypothesis accounting only for a limited number of physical properties of aerosols.
Indian mantle corner flow at southern Tibet revealed by shear wave splitting measurements
Authors: Fu Yuanyuan V. , Chen Y. John , Li Aibing , Zhou Shiyong , Liang Xiaofeng , Ye Guoyang , Jin Ge , Jiang Mingming , Ning Jieyuan
Published: January 2008

We constrain anistropic seismic structure in the southernmost Tibet and the Tethyan Himalays using SKS and SKKS phases recorded from a temporary seismic network, operated from July 2004 to August 2005 in conjunction with the Hi‐Climb project. Shear wave splitting is not detected at 16 stations, most of which are located near and to the north of the Indus‐Yalong suture (IYS). For the first time anisotropy with an N‐S fast direction and 0.4 ∼ 1 s delay times is observed to the region about 50 km south of the IYS. This weak anisotropy correlates with the flat part of the subducting Indian lithosphere and could be caused by northward asthenospheric flow and shear at the base of the Indian lithosphere. The null measurements in the vicinity of the IYS are most likely the result of a vertical asthenospheric flow, the corner flow induced by the subvertical subduction of the Indian lithosphere just south of the Bangong‐Nujiang suture (BNS). Observations of the systematic changes in mantle anisotropy from southern Tibet to the central Tibet provide evidence for different mantle flow fields between the Indian and the Eurasian asthenospheric mantle, which are separated by a subvertical Indian lithosphere at the BNS.
Surface shortwave radiative forcing of different aerosol types in the central Mediterranean
Authors: di Sarra A. , Pace G. , Meloni D. , De Silvestri L. , Piacentino S. , Monteleone F.
Published: January 2008

Ground based measurements of aerosol optical depth, τ, and shortwave irradiance at the Mediterranean island of Lampedusa during 2003 and 2004 were used to estimate the surface aerosol shortwave radiative forcing. The shortwave forcing efficiency (FE) was derived at various solar zenith angles, θ, as the derivative of the shortwave irradiance with respect to τ. Values of FE for different classes of particles, namely desert dust, DD, biomass burning/industrial aerosols, BU, and for the whole dataset are derived. At the summer solstice the daily average FE is −86.4 W/m2 for DD, −70.5 W/m2 for BU, and −94.0 W/m2 for the whole dataset. The daily aerosol forcing of DD is much larger than for the other aerosol classes due to the combination of larger forcing efficiency and largest optical depths. The estimated average daily forcing at the summer solstice and equinox for DD is −30 and −24 W/m2, respectively.
Three‐dimensional crustal structure of the Mariana island arc from seismic tomography
Authors: Calvert Andrew J. , Klemperer Simon L. , Takahashi Narumi , Kerr Bryan C.
Published: January 2008

A three‐dimensional (3‐D) seismic refraction survey was acquired over the Mariana volcanic arc at 14.5–18.5°N and 145–147°E. First‐arrival traveltimes from this survey and from a separate 2‐D survey acquired approximately perpendicular to the arc have been simultaneously inverted for a 3‐D P wave velocity model using seismic tomography subject to smoothness constraints. The active arc, which initiated only 3–4 Ma ago, has an average crustal thickness of 18 km. Approximately 40 km to the east the inactive remnant of the rifted Eocene arc has an average crustal thickness of 21 km, due primarily to a thicker lower‐crustal layer with velocities of 6.5–7.0 km s−1. Crustal production clearly varies both temporally and spatially, with some crustal layers, including the igneous fore‐arc crust, varying in thickness by a factor of up to 2 along strike. Average P wave velocities within the upper crust of the modern arc are 240–360 m s−1 lower than in the Eocene arc but are 280 m s−1 higher within the lower crust. Middle crust with velocities of 6.0–6.5 km s−1 is best developed beneath the Eocene arc. These results suggest an evolution of arc structure with increasing age: We infer closure of fractures and porosity in the upper crust through hydrothermal circulation and a reduction in the mafic character of the middle to lower crust as a result of intracrustal differentiation. Although tonalitic rocks may predominate in the transition from upper to middle crust, the bulk of the crust is essentially basaltic.
Monitoring mountain permafrost evolution using electrical resistivity tomography: A 7‐year study of seasonal, annual, and long‐term variations at Schilthorn, Swiss Alps
Authors: Hilbich C. , Hauck C. , Hoelzle M. , Scherler M. , Schudel L. , Völksch I. , Vonder Mühll D. , Mäusbacher R.
Published: January 2008

A combined geophysical and thermal monitoring approach for improved observation of mountain permafrost degradation is presented. Time‐lapse inversion of repeated electrical resistivity tomography (ERT) measurements allows both active layer dynamics and interannual permafrost conditions to be delineated. Analysis of a comprehensive ERT monitoring data set from a 7‐year study at Schilthorn, Swiss Alps, confirmed the applicability of ERT monitoring to observations of freezing and thawing processes on short‐term, seasonal, and long‐term scales. Long‐term resistivity changes were evaluated on the basis of seasonal resistivity variations showing an annual cycle with high resistivities in frozen and low resistivities in unfrozen state. One important result is the detection of a sustained impact of the extraordinarily hot European summer of 2003 on the permafrost regime, which is more severe than previously assumed from borehole temperatures. Combined analyses of ERT monitoring and borehole temperature data revealed substantial ground ice degradation as a consequence of the 2003 summer, which did not recover in the following years despite suitable subsurface temperature conditions. Resistivity changes that are nonconforming to long‐term temperature evolution are attributed to the limited availability of liquid water and/or changes in material characteristics (e.g., pore volume changes as a result of subsidence).
Ice‐front variation and tidewater behavior on Helheim and Kangerdlugssuaq Glaciers, Greenland
Authors: Joughin Ian , Howat Ian , Alley Richard B. , Ekstrom Goran , Fahnestock Mark , Moon Twila , Nettles Meredith , Truffer Martin , Tsai Victor C.
Published: January 2008

We used satellite images to examine the calving behavior of Helheim and Kangerdlugssuaq Glaciers, Greenland, from 2001 to 2006, a period in which they retreated and sped up. These data show that many large iceberg‐calving episodes coincided with teleseismically detected glacial earthquakes, suggesting that calving‐related processes are the source of the seismicity. For each of several events for which we have observations, the ice front calved back to a large, pre‐existing rift. These rifts form where the ice has thinned to near flotation as the ice front retreats down the back side of a bathymetric high, which agrees well with earlier theoretical predictions. In addition to the recent retreat in a period of higher temperatures, analysis of several images shows that Helheim retreated in the 20th Century during a warmer period and then re‐advanced during a subsequent cooler period. This apparent sensitivity to warming suggests that higher temperatures may promote an initial retreat off a bathymetric high that is then sustained by tidewater dynamics as the ice front retreats into deeper water. The cycle of frontal advance and retreat in less than a century indicates that tidewater glaciers in Greenland can advance rapidly. Greenland's larger reservoir of inland ice and conditions that favor the formation of ice shelves likely contribute to the rapid rates of advance.
Stochastic flocculation of cohesive sediment: Analysis of floc mobility within the floc size spectrum
Authors: Maggi Federico
Published: January 2008

A stochastic Lagrangian model is proposed to describe flocculation of suspended cohesive sediment flocs. This model takes into account the floc population in a parametric fashion, and predicts the time evolution of an individual floc by a sequence of stochastic aggregation and breakup events. Upon calibration on experimental data, the model was used to investigate floc mobility within the population size spectrum, bringing to light dynamical aspects not otherwise detectable with deterministic models. Our analysis showed that floc size fluctuations correlated with the population size distribution and breakup probability, and that size‐dependent burst events repeated intermittently in time. Further analysis showed the effect of the floc population distribution on individual floc size transition and equilibrium, and the effect of using either a constant or variable floc capacity dimension to describe floc geometry.
Could the Quality of Dietary Fat, and Not Just Its Quantity, Be Related to Risk of Obesity?
Authors: Moussavi Nadiah , Gavino Victor , Receveur Olivier
Published: January 2008

This review focuses on the possible association between types of fatty acids and weight change. It examines the biological plausibility underlining these associations and the evidence obtained to date from clinical trials and epidemiological studies. Animal studies have shown that dietary short‐ and medium‐chain fatty acids compared to long‐chain fatty acids appear to promote weight loss. Similarly, monounsaturated fatty acids (MUFAs) appear to favor weight loss compared to saturated fatty acids (SFAs) in human studies. The structure of fatty acids seems to affect their degree of oxidation and deposition. Although results are conflicting, human studies follow the general trend reported in animal studies. These trials suggest that some fatty acids are prone to oxidation and some others lead to fat storage when comparing isocaloric diets. For instance, n‐3 polyunsaturated fatty acids (PUFAs), eicosapentaenoic and docosahexaenoic acids are preferentially oxidizied to other PUFA but results remain inconsistent. Epidemiological studies concerning this issue reported that total dietary fat, which includes MUFA, PUFA, and SFA could increase the risk of obesity, but results are few and conflicting. The rising biological plausibility linking dietary fat quality and risk of obesity, together with the rather recent addition of fatty acids content in food composition tables, support the need for major epidemiological studies in that area.
Differences in Daily Energy Expenditure in Lean and Obese Women: The Role of Posture Allocation
Authors: Johannsen Darcy L. , Welk Gregory J. , Sharp Rick L. , Flakoll Paul J.
Published: January 2008

Objective: A low resting metabolic rate (RMR) is considered a risk factor for weight gain and obesity; however, due to the greater fat‐free mass (FFM) found in obesity, detecting an impairment in RMR is difficult. The purposes of this study were to determine the RMR in lean and obese women controlling for FFM and investigate activity energy expenditure (AEE) and daily activity patterns in the two groups.

Methods and Procedures: Twenty healthy, non‐smoking, pre‐menopausal women (10 lean and 10 obese) participated in this 14‐day observational study on free‐living energy balance. RMR was measured by indirect calorimetry; AEE and total energy expenditure (TEE) were calculated using doubly labeled water (DLW), and activity patterns were investigated using monitors. Body composition including FFM and fat mass (FM) was measured by dual energy X‐ray absorptiometry (DXA).

Results: RMR was similar in the obese vs. lean women (1601 ± 109 vs. 1505 ± 109 kcal/day, respectively, P = 0.12, adjusting for FFM and FM). Obese women sat 2.5 h more each day (12.7 ± 3.2 h vs. 10.1 ± 2.0 h, P < 0.05), stood 2 h less (2.7 ± 1.0 h vs. 4.7 ± 2.2 h, P = 0.02) and spent half as much time in activity than lean women (2.6 ± 1.5 h vs. 5.4 ± 1.9 h, P = 0.002).

Discussion: RMR was not lower in the obese women; however, they were more sedentary and expended less energy in activity than the lean women. If the obese women adopted the activity patterns of the lean women, including a modification of posture allocation, an additional 300 kcal could be expended every day.
Observational Study of Bone Accretion During Successful Weight Loss in Obese Adolescents
Authors: Stettler Nicolas , Berkowtiz Robert I. , Cronquist Joanna L. , Shults Justine , Wadden Thomas A. , Zemel Babette S. , Leonard Mary B.
Published: January 2008

Objective: To assess bone mineral content (BMC) among obese adolescents who lose weight during a critical period for bone accretion.

Methods and Procedures: Whole body, lumbar spine, lower, and upper limb BMC were measured in 62 obese adolescents who completed an intensive 12‐month weight loss trial. BMC was adjusted for height (z ‐scores) using data from a reference group of 66 adolescents (who were 18% overweight).

Results: At baseline, the BMC of the obese group was higher than the reference group. During the 12‐month weight loss program, unadjusted BMC increased among the obese adolescents, despite successful weight loss. After adjustment for height, whole body BMC did not change significantly from baseline to 12 months (mean ± s.d.: 1.08 ± 0.67 to 1.06 ± 0.67, P = 0.7). Region‐specific BMC‐for‐height however decreased for the lower (1.07 ± 0.57 to 0.95 ± 0.59, P < 0.001) and upper (1.29 ± 0.56 to 1.18 ± 0.57, P = 0.01) limbs, but lumbar spine BMC‐for‐height increased (0.14 ± 1.06 to 0.40 ± 0.94, P < 0.001). These changes were largely and independently explained by changes in lean and fat mass.

Discussion: This study confirms that obese adolescents have high BMC for height and suggests that, unlike adults, their BMC continues to increase during weight loss and remains higher than the BMC of a reference group. After adjustment for growth‐related changes, lower and upper limb BMC appears to decrease, while lumbar spine BMC appears to increase. These results suggest that to optimize the health benefits of weight loss among obese adolescents, their bone health should be better understood and addressed.
Familial Aggregation of Metabolic Syndrome and Its Components in a Large Chinese Population
Authors: Feng Yan , Zang Tonghua , Xu Xiping , Xu Xin
Published: January 2008

Objective: To investigate the familial aggregation of metabolic syndrome (MetS) and its components in the Chinese.

Methods and Procedures: A total of 17,954 subjects from 5,224 families with multiple siblings aged 25–64 years old (mean age 45.8 years, 51.6% male) were enrolled from a rural area of Anhui Province of China during 2004–2005. Anthropometric measurement, body composition, blood pressure, plasma lipids, and fasting glucose and insulin, as well as a questionnaire interview, were obtained from each participant.

Results: Significant correlations among siblings were observed in all the traits examined, including BMI, waist circumference, total body and abdominal fat percentage, fasting plasma glucose (FPG) and insulin, insulin resistance index of homeostatic model assessment (HOMA‐IR), total cholesterol, triglyceride, high‐density lipoprotein cholesterol (HDL‐C), low‐density lipoprotein cholesterol, and blood pressure, after adjustment for age, gender and some other covariates. The correlation coefficients varied from 0.18 for FPG to 0.42 for HDL‐C. In stratified analyses, we found siblings with a smaller age gap among them had higher intraclass correlation coefficients (ICCs) for most of the above phenotypes than those with a greater age difference, and the correlation of systolic blood pressure (SBP) was stronger in male siblings than that in female. If the eldest sibling is affected by MetS or any of its components, younger siblings bear a twofold to threefold higher risk for developing MetS or any of its components than those with a healthy eldest sibling.

Discussion: Our study demonstrated a significant familial resemblance as regards MetS and its components among the Chinese. Further studies are warranted to investigate specific genetic and environmental factors related to MetS in this population.
Correlates of State Legislative Action to Prevent Childhood Obesity
Authors: Cawley John , Liu Feng
Published: January 2008

Objective: To determine the factors associated with state legislative action to address childhood obesity.

Methods and Procedures: This paper has an ecologic study design, with data on each US state from 2003 to 2006. Data on whether a bill was introduced in the state legislature and whether a law was enacted to address childhood obesity were linked to a rich set of independent variables concerning state political and socioeconomic characteristics that were drawn from a variety of sources. The association between state legislative action and state political and socioeconomic characteristics was measured using probit regression.

Results: From 2003 to 2005 there was an increasing trend toward the introduction of bills and enactment of laws to address childhood obesity. State legislative action on childhood obesity was more likely in states with a greater gap between adults' actual and desired weight, a higher percentage of college‐educated adults, a higher percentage of African‐American residents, a Democratic governor, or a legislature not controlled by Republicans.

Discussion: The socioeconomic conditions of the state and its political climate strongly predict legislative action to address childhood obesity. The finding that Democratic governors and state legislatures not controlled by Republicans are associated with greater policy action against obesity suggests that the 2006 election may result in additional action against obesity in certain states. This study can also be used to guide the efforts of public health advocates, who can achieve greater success by targeting their efforts toward states with conducive political environments.
Alteration of Dietary Fat Intake to Prevent Weight Gain: Jayhawk Observed Eating Trial
Authors: Donnelly Joseph E. , Sullivan Debra K. , Smith Bryan K. , Jacobsen Dennis J. , Washburn Richard A. , Johnson Susan L. , Hill James O. , Mayo Matthew S. , Spaeth Kendra R. , Gibson Cheryl
Published: January 2008

Objective: To examine the effects of ad libitum diets with three distinct levels of fat intake for the prevention of weight gain in sedentary, normal‐weight and overweight men and women.

Methods and Procedures: Three hundred and five participants were randomized to one of three diets. The diets targeted <25% of energy from fat (low fat (LF)), between 28 and 32% of energy from fat (moderate fat (MF)), or >35% of energy from fat (high fat (HF)). Participants consumed two meals per day on weekdays and one meal per day on weekends in a university cafeteria over a 12‐week period. Energy and nutrient content of cafeteria foods were measured by digital photography. All meals and snacks consumed outside the cafeteria were measured by dietary recall. All analysis of energy and nutrient content was completed using Nutrition Data System for Research (NDS‐R) version 2005.

Results: Two hundred and sixty participants completed the study. LF gained 0.1 ± 3.1 kg, MF gained 0.8 ± 2.5 kg, and HF gained 1.0 ± 2.2 kg and there was no gender or age effect. Longitudinal mixed modeling indicated a significant difference among the groups in weight over time (P = 0.0366). When adjusting for total energy intake, which was a significant predictor of weight over time, the global effect for the group was eliminated. Thus, increasing weight was a function of increasing energy but not increasing percentage of fat intake.

Discussion: Energy intake, but not percentage of energy from fat, appears responsible for the observed weight gain. LF diets may contribute to weight maintenance and HF diets may promote weight gain due to the influence of fat intake on total energy intake.
Gender Differences in Predictors of Body Weight and Body Weight Change in Healthy Adults
Authors: Chiriboga David E. , Ma Yunsheng , Li Wenjun , Olendzki Barbara C. , Pagoto Sherry L. , Merriam Philip A. , Matthews Charles E. , Hebert James R. , Ockene Ira S.
Published: January 2008

Background: Overweight and obesity are important predictors of a wide variety of health problems. Analysis of naturally occurring changes in body weight can provide valuable insights in improving our understanding of the influence of demographic, lifestyle, and psychosocial factors on weight gain in middle‐age adults.

Objective: To identify gender‐specific predictors of body weight using cross‐sectional and longitudinal analyses.

Methods and Procedures: Anthropometric, lifestyle and psychosocial factors were measured at baseline and then quarterly for 1 year in 572 healthy adult volunteers from Central Massachusetts who were recruited between 1994 and 1998. Linear mixed models were used to analyze the relationship between body weight and potential predictors, including demographic (e.g., age, educational level), lifestyle (e.g., diet, physical activity, smoking), and psychosocial (e.g., anxiety, depression) factors.

Results: Over the 1‐year study period, on average, men gained 0.3 kg and women lost 0.2 kg. Predictors of lower body weight at baseline in both men and women included current cigarette smoking, greater leisure‐time physical activity, and lower depression and anxiety scores. Lower body weights were associated with a lower percentage of caloric intake from protein and greater occupational physical activity levels only among men; and with higher education level only among women. Longitudinal predictors of 1‐year weight gain among women included increased total caloric intake and decreased leisure‐time physical activity, and among men, greater anxiety scores.

Discussion: Demographic, lifestyle and psychosocial factors are independently related to naturally occurring changes in body weight and have marked differential gender effects. These effects should be taken into consideration when designing interventions for weight‐loss and maintenance at the individual and population levels.
Obesity and Physical Activity Among Aboriginal Canadians
Authors: Katzmarzyk Peter T.
Published: January 2008

Objective: To investigate ethnic differences in obesity and physical activity among Aboriginal and non‐Aboriginal Canadians.

Methods and Procedures: The sample included 24,279 Canadians (1,176 Aboriginals, 23,103 non‐Aboriginals) aged 2–64 years from the 2004 Canadian Community Health Survey (CCHS). Adult participants were classified as underweight/normal weight, overweight (BMI 25–29.9 kg/m2) or obese (BMI ≥ 30 kg/m2). Children and youth 2–17 years of age were classified as normal weight, overweight or obese based on the International Obesity Task Force criteria. Leisure‐time physical activity levels over the previous 3 months were obtained by questionnaire in those aged 12–64 years.

Results: The prevalence of obesity in adults was 22.9% (men: 22.9%; women: 22.9%), and the prevalence was higher among Aboriginals (37.8%) compared to non‐Aboriginals (22.6%). The prevalence of obesity in children and youth was 8.2% (boys: 9.2%; girls: 7.2%), and the prevalence was higher among Aboriginals (15.8%) compared to non‐Aboriginals (8.0%). In both youth and adults, the odds for obesity were higher among Aboriginals (youth: OR = 2.3 (95% CI: 1.4–3.8); adults: OR = 2.4 (95% CI: 1.6–3.6)) after adjustment for a number of covariates. There were no ethnic differences in the prevalence of physical inactivity; however, physical inactivity was a predictor of obesity in both the Aboriginal and non‐Aboriginal samples.

Discussion: The prevalence of obesity is higher among Canadian Aboriginals compared to the rest of the population. Further research is required to better delineate the determinants of obesity and the associated health consequences in this population.
Metabolic Syndrome and Health‐related Quality of Life in Obese Individuals Seeking Weight Reduction
Authors: Tsai Adam Gilden , Wadden Thomas A. , Sarwer David B. , Berkowitz Robert I. , Womble Leslie G. , Hesson Louise A. , Phelan Suzanne , Rothman Rebecca
Published: January 2008

Background: No previous research has examined the association between metabolic syndrome (MetSyn) and health‐related quality of life (HRQoL) using standard criteria for defining MetSyn. We hypothesized that MetSyn would be associated with lower HRQoL on measures of physical and mental health.

Methods and Procedures: Participants were 361 individuals in two randomized weight loss trials. MetSyn was defined by the National Cholesterol Education Panel criteria. The Medical Outcomes Study, Short Form‐36 (SF‐36) was used to assess HRQoL. Differences in HRQoL and in clinical and psychosocial characteristics were compared among participants with and without MetSyn. Multiple regression was used to determine predictors of HRQoL.

Results: MetSyn was associated with lower scores on the physical function and general health subscales of the SF‐36 and on the physical component summary (PCS) score. This association remained after controlling for age or depression but was eliminated by controlling for BMI. MetSyn was not associated with lower mental quality of life, a higher depression score, tobacco or alcohol use, or a higher rate of psychosocial stressors.

Discussion: Individuals with MetSyn reported lower HRQoL. This appeared to be an effect of increased weight, rather than a unique effect of MetSyn. Larger studies are needed to assess whether MetSyn may have an independent effect on HRQoL.
Reaction of carbon monoxide and hydrogen on neutral Nb8 clusters in the gas phase
Authors: Xie Y. , He S.-G. , Dong F. , Bernstein E. R.
Published: January 2008

Reactions of neutral Vn, Nbn, and Tan metal clusters (n⩽11) with CO+H2 mixed gases and CH3OH in a flow tube reactor (1–50Torr) are studied by time of flight mass spectroscopy and density functional theory calculations. Metal clusters are generated by laser ablation, and reactants and products are ionized by low fluence (∼200μJ∕cm2) 193nm excimer laser light. Nbn clusters exhibit strong size dependent reactivity in reactions both with CO+H2 and CH3OH compared with Vn and Tan clusters. A “magic number” (relatively intense) mass peak at Nb8COH4 is observed in the reaction of Nbn clusters with CO+H2, and CH3OH is suggested to be formed. This feature at Nb8COH4 remains the most intense peak independent of the relative concentrations of CO and H2 in the flow tube reactor. No other Nbn, Tan, or Vn feature behaves in this manner. In reactions of CH3OH with metal clusters Mn (M=V, Nb, and Ta, n=3–11), nondehydrogenated products MnCOH4∕MnCH3OH are only observed on Nb8 and Nb10, whereas dehydrogenated products MnCO∕CMnO are observed for all other clusters. These observations support the suggestion that CH3OH can be formed on Nb8 in the reaction of Nbn with CO+H2. A reaction mechanism is suggested based on the experimental results and theoretical calculations of this work and of those in the literature. Methanol formation from CO+H2 on Nb8 is overall barrierless and thermodynamically and kinetically favorable.
Limitation of the electromagnetic cloak with dispersive material
Authors: Yao Peijun , Liang Zixian , Jiang Xunya
Published: January 2008

Based on causality, the limitation of the electromagnetic cloak with dispersive material is investigated in this letter. The results show that perfect invisibility cannot be achieved because of the dilemma that either the group velocity Vg diverges or a strong absorption is imposed on the cloaking material. It is an intrinsic conflict which originates from the demand of causality. However, the total cross section can really be reduced through the approach of coordinate transformation. A simulation of finite-difference time-domain method is performed to validate our analysis.
Critical conditions for stable dipole-bound dianions
Authors: Ferrón Alejandro , Serra Pablo , Kais Sabre
Published: January 2008

We present finite size scaling calculations of the critical parameters for binding two electrons to a finite linear dipole field. This approach gives very accurate results for the critical parameters by using a systematic expansion in a finite basis set. A complete ground state stability diagram for the dipole-bound dianion is obtained using accurate variational and finite size scaling calculations. We also study the near threshold behavior of the ground state energy by calculating its critical exponent.
Theory for an order-driven disruption of the liquid state in water
Authors: England Jeremy L. , Park Sanghyun , Pande Vijay S.
Published: January 2008

Water is known to exhibit a number of peculiar physical properties because of the strong orientational dependence of the intermolecular hydrogen bonding interactions that dominate its liquid state. Recent full-atom simulations of water in a nanolayer between graphite plates submersed in an aqueous medium have raised the possibility of a new addition to this list of peculiarities: they show that application of a strong, uniform electric field normal to and between the plates can cause a pronounced decrease in particle density, rather than the increase expected from electrostriction theory for polarizable fluids [Vaitheeswaran et al., J. Phys. Chem. B 70, 6629 (2005)]. However, in seeming contradiction to this result, another study that simulated a range of similar systems has reported a less surprising electrostrictive increase in particle density upon application of the field [Bratko et al., J. Am. Chem. Soc. 129, 2504 (2007)]. In this work, we attempt to reconcile these conflicting simulation phenomena using a statistical mechanical lattice liquid model of water in an applied field. By solving the model using mean-field theory, we show that a field-induced transition to a markedly lower-density phase such as that observed in recent simulations is possible within a certain parameter regime, but that outside of this regime, the more conventional electrostrictive result should be obtained. Upon modifying the model to treat the case of bulk water under constant pressure in an applied field, we predict a density drop with rising field, and subsequently observe the predicted behavior in our own molecular dynamics simulations of liquid water. Our findings lead us to propose that the model considered here may be useful in a variety of contexts for describing the trade-off between orientational ordering of water molecules and their participation in the liquid phase.
A new anisotropic soft-core model for the simulation of liquid crystal mesophases
Authors: Lintuvuori Juho S. , Wilson Mark R.
Published: January 2008

A new anisotropic soft-core model is presented, which is suitable for the rapid simulation of liquid crystal mesophases. The potential is based on a soft spherocylinder, which can be easily tuned to favor different liquid crystal mesophases. The soft-core nature of the potential makes it suitable for long-time step molecular dynamics or dissipative particle dynamics simulations, particularly as a reference model for mesogens or as an anisotropic solvent for use in combination with atomistic models. Results are presented for two variants of the new potential, which show different mesophase behaviors. Variants of the potential can also be linked together to produce more complicated molecular structures. Here, as an example, results are provided for a model multipedal liquid crystal, which has eight liquid crystalline groups linked to a central core via semiflexible chains. Here, despite the complexity of molecular structure, the model succeeds in showing the spontaneous formation of a liquid crystal phase. The results also demonstrate that there is a very strong coupling between the internal structure of the multipedal mesogen and the molecular order of the phase, with the mesogen spontaneously undergoing major structural rearrangement at the transition to the liquid crystal phase.
Magnetization and magnetocaloric effect in ball-milled zinc ferrite powder
Authors: Gass J. , Srikanth H. , Kislov N. , Srinivasan S. S. , Emirov Y.
Published: January 2008

Enhancement of magnetocaloric effect (MCE) in nanostructured materials is important for refrigeration applications such as spot cooling in microelectromechanical system devices. Here we report the first investigation of MCE properties in ball-milled ZnFe2O4 particles. The MCE was obtained by measuring a family of M-H curves at set temperature intervals and calculating the entropy change (ΔS) for this system using the Maxwell relation. The surface structure of zinc ferrite particles is sensitive to ball milling conditions and we observed that these surface effects greatly impact the MCE and our observations could provide a route for its potential enhancement by controlled surface modification.
Interpretation of edge pedestal rotation measurements in DIII-D
Authors: Stacey W. M. , Groebner R. J.
Published: January 2008

A novel methodology for inferring experimental toroidal angular momentum transfer rates from measured toroidal rotation velocities and other measured quantities has been developed and applied to analyze rotation measurements in the DIII-D [J. Luxon, Nucl. Fusion 42, 6149 (2002)] edge pedestal. The experimentally inferred values have been compared with predictions based on atomic physics processes and on neoclassical toroidal viscosity. The poloidal rotation velocities have been calculated from poloidal momentum balance using neoclassical parallel viscosity and a novel retention of all terms in the poloidal momentum balance, and compared with measured values in the DIII-D edge pedestal.
Epitaxial growth of colossal magnetoresistive films onto Si(100)
Authors: Hu F. X. , Sun J. R. , Shen B. G. , Rong C. B. , Gao J.
Published: January 2008

We report the growth of colossal magnetoresistive (CMR) films La0.7Ca0.3MnO3 (LCMO) and La0.9Ba0.1MnO3 (LBMO) onto Si (100) using a simple pulsed-laser deposition technique. To avoid oxidation of the Si surface, an initial growth of SrTiO3 of a few atomic layers was carried out. We found that epitaxial growth of LCMO and LBMO films on Si can be realized by optimizing the deposition process. The obtained LCMO and LBMO films show ferromagnetic nature and the resulted LCMO/Si and LBMO/Si heterojunctions exhibit good rectifying behavior with magnetically tunable characteristics.