Nanoelectromechanical coupling in fullerene peapods probed via resonant electrical transport experiments

Fullerene peapods, that is carbon nanotubes encapsulating fullerene molecules, can offer enhanced functionality with respect to empty nanotubes. However, the present incomplete understanding of how a nanotube is affected by entrapped fullerenes is an obstacle for peapods to reach their full potential in nanoscale electronic applications. Here, we investigate the effect of C60 fullerenes on electron transport via peapod quantum dots. Compared to empty nanotubes, we find an abnormal temperature dependence of Coulomb blockade oscillations, indicating the presence of a nanoelectromechanical coupling between electronic states of the nanotube and mechanical vibrations of the fullerenes. This provides a method to detect the C60 presence and to probe the interplay between electrical and mechanical excitations in peapods, which thus emerge as a new class of nanoelectromechanical systems.Comment: 7 pages, 3 figures. Published in Nature Communications. Free online access to the published version until Sept 30th, 2010, see http://www.nature.com/ncomms/journal/v1/n4/abs/ncomms1034.htm

Emergence of robust growth laws from optimal regulation of ribosome synthesis

Bacteria must constantly adapt their growth to changes in nutrient availability; yet despite large‐scale changes in protein expression associated with sensing, adaptation, and processing different environmental nutrients, simple growth laws connect the ribosome abundance and the growth rate. Here, we investigate the origin of these growth laws by analyzing the features of ribosomal regulation that coordinate proteome‐wide expression changes with cell growth in a variety of nutrient conditions in the model organism Escherichia coli. We identify supply‐driven feedforward activation of ribosomal protein synthesis as the key regulatory motif maximizing amino acid flux, and autonomously guiding a cell to achieve optimal growth in different environments. The growth laws emerge naturally from the robust regulatory strategy underlying growth rate control, irrespective of the details of the molecular implementation. The study highlights the interplay between phenomenological modeling and molecular mechanisms in uncovering fundamental operating constraints, with implications for endogenous and synthetic design of microorganisms.ISSN:1744-429

Scents of Adolescence: The Maturation of the Olfactory Phenotype in a Free-Ranging Mammal

Olfaction is an important sensory modality for mate recognition in many mammal species. Odorants provide information about the health status, genotype, dominance status and/or reproductive status. How and when odor profiles change during sexual maturation is, however often unclear, particularly in free-ranging mammals. Here, we investigated whether the wing sac odorant of male greater sac-winged bats (Saccopteryx bilineata, Emballonuridae) differs between young and adults, and thus offers information about sexual maturity to potential mating partners. Using gas chromatography – mass spectrometry, we found differences in the odorants of young and adult males prior and during, but not after the mating period. The wing sac odorant of adult males consists of several substances, such as Pyrocoll, 2,6,10-trimethyl-3-oxo-6,10-dodecadienolide, and a so far unidentified substance; all being absent in the odor profiles of juveniles prior to the mating season. During the mating season, these substances are present in most of the juvenile odorants, but still at lower quantities compared to the wing sac odorants of adults. These results suggest that the wing sac odorant of males encodes information about age and/or sexual maturity. Although female S. bilineata start to reproduce at the age of half a year, most males of the same age postpone the sexual maturation of their olfactory phenotype until after the first mating season

Estimating the Diets of Animals Using Stable Isotopes and a Comprehensive Bayesian Mixing Model

Using stable isotope mixing models (SIMMs) as a tool to investigate the foraging ecology of animals is gaining popularity among researchers. As a result, statistical methods are rapidly evolving and numerous models have been produced to estimate the diets of animals—each with their benefits and their limitations. Deciding which SIMM to use is contingent on factors such as the consumer of interest, its food sources, sample size, the familiarity a user has with a particular framework for statistical analysis, or the level of inference the researcher desires to make (e.g., population- or individual-level). In this paper, we provide a review of commonly used SIMM models and describe a comprehensive SIMM that includes all features commonly used in SIMM analysis and two new features. We used data collected in Yosemite National Park to demonstrate IsotopeR's ability to estimate dietary parameters. We then examined the importance of each feature in the model and compared our results to inferences from commonly used SIMMs. IsotopeR's user interface (in R) will provide researchers a user-friendly tool for SIMM analysis. The model is also applicable for use in paleontology, archaeology, and forensic studies as well as estimating pollution inputs

Inhibition, Reinforcement Sensitivity and Temporal Information Processing in ADHD and ADHD+ODD: Evidence of a Separate Entity?

This study compared children with ADHD-only, ADHD+ODD and normal controls (age 8–12) on three key neurocognitive functions: response inhibition, reinforcement sensitivity, and temporal information processing. The goal was twofold: (a) to investigate neurocognitive impairments in children with ADHD-only and children with ADHD+ODD, and (b) to test whether ADHD+ODD is a more severe from of ADHD in terms of neurocognitive performance. In Experiment 1, inhibition abilities were measured using the Stop Task. In Experiment 2, reinforcement sensitivity and temporal information processing abilities were measured using a Timing Task with both a reward and penalty condition. Compared to controls, children with ADHD-only demonstrated impaired inhibitory control, showed more time underestimations, and showed performance deterioration in the face of reward and penalty. Children with ADHD+ODD performed in-between children with ADHD-only and controls in terms of inhibitory controls and the tendency to underestimate time, but were more impaired than controls and children with ADHD-only in terms of timing variability. In the face of reward and penalty children with ADHD+ODD improved their performance compared to a neutral condition, in contrast to children with ADHD-only. In the face of reward, the performance improvement in the ADHD+ODD group was disproportionally larger than that of controls. Taken together the findings suggest that, in terms of neurocognitive functioning, comorbid ADHD+ODD is a substantial different entity than ADHD-only

Changing boreal methane sources and constant biomass burning during the last termination

Past atmospheric methane concentrations show strong fluctuations in parallel to rapid glacial climate changes in the Northern Hemisphere superimposed on a glacial–interglacial doubling of methane concentrations. The processes driving the observed fluctuations remain uncertain but can be constrained using methane isotopic information from ice cores. Here we present an ice core record of carbon isotopic ratios in methane over the entire last glacial–interglacial transition. Our data show that the carbon in atmospheric methane was isotopically much heavier in cold climate periods. With the help of a box model constrained by the present data and previously published results, we are able to estimate the magnitude of past individual methane emission sources and the atmospheric lifetime of methane. We find that methane emissions due to biomass burning were about 45 Tg methane per year, and that these remained roughly constant throughout the glacial termination. The atmospheric lifetime of methane is reduced during cold climate periods. We also show that boreal wetlands are an important source of methane during warm events, but their methane emissions are essentially shut down during cold climate conditions

Abstract P5-06-02: Proliferative breast disease identified by nipple aspirate fluid cytopathology has the laterality and asymmetry characteristics of breast cancer, supporting the thesis it is a cancer precursor

Abstract Introduction. Within the basket of conditions known as Benign Breast Disease, Proliferative Breast Disease (PBD) is a finding at biopsy or aspiration of either benign hyperplasia or atypical hyperplasia (ADH). PBD is known to confer increased risk of future breast cancer [Hartmann, NEJM 2015;372:78-89]. However, there is some controversy as to whether these lesions are precursors to breast cancer (BCa), in which their synchronicity and asymmetry should match BCa, or alternatively, if they are biomarkers of risk, in which future cancers would not necessarily be linked in time and space to earlier PBD lesions. The Left-dominant asymmetry was first described over half a century ago, but its molecular origins in embryonic development have only recently been characterized.[Wilting. J.Current Medic Chem 2011; 18:5519-27]. This study was conducted to explore if a similar pattern of asymmetry and unilateral v. bilateral incidence might exist in PBD. This could help to resolve the question of whether PBD is a precursor to BCa or merely a biomarker. Methods. We examined Nipple Aspirate Fluid (NAF) for evidence of proliferative cytopathology, defined as a finding of either hyperplasia or ADH. NAF was collected using either one of two models of aspirator devices (ForeCYTE™ or HALO™). NAF is aspirated, dispersed on a flower filter, sprayed with fixative and stained with the Pap stain prior to cytologic characterization. Filters mounted whole on glass are placed directly under the microscope. This method allows for a diagnostically interpretable specimen in NAF-droplets as little as 0.007 µL, 1000-fold smaller than the unassisted visual detection limit. A central lab evaluated all specimens. Results. Between 1/2012 and 6/2013, 1154 women without prior BCa (Age range 18-85; median 48, mean 47.9) consented to submit bilateral NAF specimens; 99.7% of breasts yielded NAF adequate for analysis, evidenced by presence of a duct-selective protein assay on the filter. PBD was found in 149 women, of whom 24 bilateral. The distribution is shown in the table below. Distribution of benign and atypical hyperplasia among 149 women with PBD Left-onlyRight onlyBilateralCCR 4594218CCR 51684CCR4 (L) and CCR5 (R)--2Total Women755024King Classification: CCR4 = Benign hyperplasia; CCR5 - Atypical Hyperplasia (ADH) Benign hyperplasia was found in 121 women: 10.5% of those tested. It was bilateral in 13% of cases and left-sided only in 57%. ADH was found in 30 women or 2.6% of those tested. When present, ADH was bilateral in 13% (4/30), L-sided only 53% (16/30) and R-sided only 33% (10/30) of the time. Total PBD identified by NAF cytopathology occurred in 13% (149/1154) of this population, was bilateral in 16.1% (24/149), L-only in 50.3% (75/149)and R-only in 33.5% 50/149). The excess left-sided occurrence of 17% was significant (p=0.048 by chi-square). Conclusion. This is the first report describing laterality and symmetry of PBD as made by non-invasive NAF collection and demonstrates that the pattern observed is similar to what is seen with invasive breast cancer and in situ lesions, supporting the hypothesis that PBD are precursor lesions to breast cancer. Citation Format: Kylstra JW, Kalnoski MH, Vo T, Lee ML, Chen S-C, Quay SC. Proliferative breast disease identified by nipple aspirate fluid cytopathology has the laterality and asymmetry characteristics of breast cancer, supporting the thesis it is a cancer precursor. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P5-06-02.</jats:p