Polarons, the combined motion of electrons in a cloth of their lattice distortions, are a key transport feature in doped manganites. To develop a profound understanding of the colossal resistance ...effects induced by external fields, the study of polaron correlations and the resulting collective polaron behavior, i.e., polaron ordering and transition from polaronic transport to metallic transport is essential. We show that static long-range ordering of Jahn-Teller polarons forms a polaron solid which represents a new type of charge and orbital ordered state. The related noncentrosymmetric lattice distortions establish a connection between colossal resistance effects and multiferroic properties, i.e., the coexistence of ferroelectric and antiferromagnetic ordering. Colossal resistance effects due to an electrically induced polaron solid-liquid transition are directly observed in a transmission electron microscope with local electric stimulus applied in situ using a piezo-controlled tip. Our results shed light onto the colossal resistance effects in magnetic field and have a strong impact on the development of correlated electron-device applications such as resistive random access memory (RRAM).
Mixed land use, residential density, street connectivity, and commute distance have been identified as potential variables affecting transport-related physical activity (TPA) behaviors. In this ...study, objectively measured urban design variables and TPA behaviors for adults who commuted to an occupation (
n=364) were examined. Utilitarian walking and cycling for other purposes were not investigated. Commute distance was negatively associated with TPA behaviors. Logistic regression analysis identified respondents who commuted through the most connected streets were more likely to engage in TPA modes to access their occupation (OR=6.9) when compared to those traveling along the least connected. No other associations between TPA behaviors and urban variables were shown. Improved street connectivity and reduced commute distances will likely support TPA.
C. V. Starr Laboratory for Molecular Neuropharmacology, Department of Anesthesiology, Weill Medical College, Cornell University, New York, New York
Submitted 25 April 2005;
accepted in final form 4 ...September 2005
Whole cell patch-clamp recordings were obtained from thalamic ventrobasal (VB) and reticular (RTN) neurons in mouse brain slices. A bicuculline-sensitive tonic current was observed in VB, but not in RTN, neurons; this current was increased by the GABA A receptor agonist 4,5,6,7-tetrahydroisothiazolo-5,4-cpyridine-3-ol (THIP; 0.1 µM) and decreased by Zn 2+ (50 µM) but was unaffected by zolpidem (0.3 µM) or midazolam (0.2 µM). The pharmacological profile of the tonic current is consistent with its generation by activation of GABA A receptors that do not contain the 1 or 2 subunits. GABA A receptors expressed in HEK 293 cells that contained 4 2 subunits showed higher sensitivity to THIP (gaboxadol) and GABA than did receptors made up from 1 2 , 4 2 2s, or 1 2 2s subunits. Western blot analysis revealed that there is little, if any, 3 or 5 subunit protein in VB. In addition, co-immunoprecipitation studies showed that antibodies to the subunit could precipitate 4 , but not 1 subunit protein. Confocal microscopy of thalamic neurons grown in culture confirmed that 4 and subunits are extensively co-localized with one another and are found predominantly, but not exclusively, at extrasynaptic sites. We conclude that thalamic VB neurons express extrasynaptic GABA A receptors that are highly sensitive to GABA and THIP and that these receptors are most likely made up of 4 2 subunits. In view of the critical role of thalamic neurons in the generation of oscillatory activity associated with sleep, these receptors may represent a principal site of action for the novel hypnotic agent gaboxadol.
Address for reprint requests and other correspondence: P. A. Goldstein, Dept. of Anesthesiology, Weill Medical College, Cornell University, 1300 York Ave., Room A-1050, New York, NY 10021 (E-mail: pag2014{at}med.cornell.edu )
Numerous taxonomic groups exhibit an evolutionary trajectory in cell or body size. The size structure of marine phytoplankton communities strongly affects food web structure and organic carbon export ...into the ocean interior, yet macroevolutionary patterns in the size structure of phytoplankton communities have not been previously investigated. We constructed a database of the size of the silica frustule of the dominant fossilized marine planktonic diatom species over the Cenozoic. We found that the minimum and maximum sizes of the diatom frustule have expanded in concert with increasing species diversity. In contrast, the mean area of the diatom frustule is highly correlated with oceanic temperature gradients inferred from the δ18O of foraminiferal calcite, consistent with the hypothesis that climatically induced changes in oceanic mixing have altered nutrient availability in the euphotic zone and driven macroevolutionary shifts in the size of marine pelagic diatoms through the Cenozoic.
Heterotrophic marine bacteria utilize organic carbon for growth and biomass synthesis. Thus, their physiological variability is key to the balance between the production and consumption of organic ...matter and ultimately particle export in the ocean. Here we investigate a potential link between bacterial traits and ecosystem functions in the rapidly warming West Antarctic Peninsula (WAP) region based on a bacteria-oriented ecosystem model. Using a data assimilation scheme, we utilize the observations of bacterial groups with different physiological traits to constrain the group-specific bacterial ecosystem functions in the model. We then examine the association of the modeled bacterial and other key ecosystem functions with eight recurrent modes representative of different bacterial taxonomic traits. Both taxonomic and physiological traits reflect the variability in bacterial carbon demand, net primary production, and particle sinking flux. Numerical experiments under perturbed climate conditions demonstrate a potential shift from low nucleic acid bacteria to high nucleic acid bacteria-dominated communities in the coastal WAP. Our study suggests that bacterial diversity via different taxonomic and physiological traits can guide the modeling of the polar marine ecosystem functions under climate change.
Abstract Purpose We compared the effectiveness of 2 physical activity prescriptions delivered in primary care—the standard time-based Green Prescription and a pedometer step-based Green ...Prescription—on physical activity, body mass index (BMI), blood pressure, and quality of life in low-active older adults. Methods We undertook a randomized controlled trial involving 330 low-active older adults (aged ≥65 years) recruited through their primary care physicians’ patient databases. Participants were randomized to either the pedometer step-based Green Prescription group (n = 165) or the standard Green Prescription group (n = 165). Both groups had a visit with the primary care practitioner and 3 telephone counseling sessions over 12 weeks aimed at increasing physical activity. Outcomes were the changes in physical activity (assessed with the Auckland Heart Study Physical Activity Questionnaire), blood pressure, BMI, quality of life (assessed with the 36-Item Short Form Health Survey), physical function status (assessed with the Short Physical Performance Battery), and falls over a 12-month period. Results Of the patients invited to participate, 57% responded. At 12 months, leisure walking increased by 49.6 min/wk for the pedometer Green Prescription compared with 28.1 min/wk for the standard Green Prescription ( P = .03). For both groups, there were significant increases across all physical activity domains at 3 months (end of intervention) that were largely maintained after 12 months of follow-up. BMI did not change in either group. Significant improvements in blood pressure were observed for both groups without any differences between them. Conclusion Pedometer use resulted in a greater increase in leisure walking without any impact on overall activity level. All participants increased physical activity, and on average, their blood pressure decreased over 12 months, although the clinical relevance is unknown.
Drifting cylindrical traps and the flux proxy 234Th indicate more than an order of magnitude higher sinking fluxes of particulate carbon and 234Th in January 2009 than measured by a time‐series ...conical trap used regularly on the shelf of the west Antarctic Peninsula (WAP). The higher fluxes measured in this study have several implications for our understanding of the WAP ecosystem. Larger sinking fluxes result in a revised export efficiency of at least 10% (C flux/net primary production) and a requisite lower regeneration efficiency in surface waters. High fluxes also result in a large supply of sinking organic matter to support subsurface and benthic food webs on the continental shelf. These new findings call into question the magnitude of seasonal and interannual variability in particle flux and reaffirm the difficulty of using moored conical traps as a quantitative flux collector in shallow waters.
One of the major immediate and long-term health issues in modern society is the problem of overweight and obesity. This paper examines the role of the workplace in the problem by studying the ...association between occupational sitting time and overweight and obesity (body mass index BMI ≥25) in a sample of adult Australians in full-time employment.
Data on age, gender, occupation, physical activity, occupational sitting time, and BMI were collected in September 2003 from a sample of 1579 adult men and women in full-time employment at the time of the survey. Logistic regression was used to examine the association between occupational sitting time and overweight and obesity.
Mean occupational sitting time was >3 hours/day, and significantly higher in men (209 minutes) than in women (189 minutes,
p=0.026). Univariate analyses showed significant associations between occupational sitting time and BMI of ≥25 in men but not in women. After adjusting for age, occupation, and physical activity, the odds ratio for BMI ≥25 was 1.92 (confidence interval: 1.17–3.17) in men who reported sitting for >6 hours/day, compared with those who sat for <45 minutes/day.
Occupational sitting time was independently associated with overweight and obesity in men who were in full-time paid work. These results suggest that the workplace may play an important role in the growing problem of overweight and obesity. Further research is needed to clearly understand the association between sitting time at work and overweight and obesity in women.
Multiple methods of grafting graphene oxide (GO) nanosheets to natural clinoptilolite-rich zeolite particles were developed in our laboratory. In this study, we have systematically characterized the ...GO coated particles prepared by various methods to select the most promising method for further research efforts. This study revealed that the most promising coating method was the clean-acid-treated zeolite particles followed by deposition of GO nanosheets onto the zeolite surface and mild thermal treatment of the particles. GO and its synergistic interaction in zeolite was attributed to electrostatic interactions, hydrophobic interactions and hydrogen bonds. Hydrophobic interactions are enhanced both due to dealumination of zeolite caused by the cleaning method followed by acid treatment and due to partial thermal deoxygenation of GO. This method provided a ten times larger surface area (from 10.55 m
g
to 117.96 m
g
) and three times smaller pore diameter (from 81.91 Å to 30.68 Å), providing great particles for a variety of applications as adsorbents or catalysts.
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