Sex differences in the influence of body mass index on anatomical architecture of brain networks.

Background/objectivesThe brain has a central role in regulating ingestive behavior in obesity. Analogous to addiction behaviors, an imbalance in the processing of rewarding and salient stimuli results in maladaptive eating behaviors that override homeostatic needs. We performed network analysis based on graph theory to examine the association between body mass index (BMI) and network measures of integrity, information flow and global communication (centrality) in reward, salience and sensorimotor regions and to identify sex-related differences in these parameters.Subjects/methodsStructural and diffusion tensor imaging were obtained in a sample of 124 individuals (61 males and 63 females). Graph theory was applied to calculate anatomical network properties (centrality) for regions of the reward, salience and sensorimotor networks. General linear models with linear contrasts were performed to test for BMI and sex-related differences in measures of centrality, while controlling for age.ResultsIn both males and females, individuals with high BMI (obese and overweight) had greater anatomical centrality (greater connectivity) of reward (putamen) and salience (anterior insula) network regions. Sex differences were observed both in individuals with normal and elevated BMI. In individuals with high BMI, females compared to males showed greater centrality in reward (amygdala, hippocampus and nucleus accumbens) and salience (anterior mid-cingulate cortex) regions, while males compared to females had greater centrality in reward (putamen) and sensorimotor (posterior insula) regions.ConclusionsIn individuals with increased BMI, reward, salience and sensorimotor network regions are susceptible to topological restructuring in a sex-related manner. These findings highlight the influence of these regions on integrative processing of food-related stimuli and increased ingestive behavior in obesity, or in the influence of hedonic ingestion on brain topological restructuring. The observed sex differences emphasize the importance of considering sex differences in obesity pathophysiology

Exchange bias in laterally oxidized Au/Co/Au nanopillars

Au/Co/Au nanopillars fabricated by colloidal lithography of continuous trilayers exhibit and enhanced coercive field and the appearance of an exchange bias field with respect to the continuous layers. This is attributed to the lateral oxidation of the Co interlayer that appears upon disc fabrication. The dependence of the exchange bias field on the Co nanodots size and on the oxidation degree is analyzed and its microscopic origin clarified by means of Monte Carlo simulations based on a model of a cylindrical dot with lateral core/shell structure.Comment: 8 pages, 4 figures. Published in Appl. Phys. Let

Coupling of individual quantum emitters to channel plasmons.

Efficient light-matter interaction lies at the heart of many emerging technologies that seek on-chip integration of solid-state photonic systems. Plasmonic waveguides, which guide the radiation in the form of strongly confined surface plasmon-polariton modes, represent a promising solution to manipulate single photons in coplanar architectures with unprecedented small footprints. Here we demonstrate coupling of the emission from a single quantum emitter to the channel plasmon polaritons supported by a V-groove plasmonic waveguide. Extensive theoretical simulations enable us to determine the position and orientation of the quantum emitter for optimum coupling. Concomitantly with these predictions, we demonstrate experimentally that 42% of a single nitrogen-vacancy centre emission efficiently couples into the supported modes of the V-groove. This work paves the way towards practical realization of efficient and long distance transfer of energy for integrated solid-state quantum systems.E.B.-U., R.M., M.G. and R.Q. acknowledge the European Community’s Seventh Framework Programme (grant ERC- Plasmolight; no. 259196) and Fundació privada CELLEX. E.B.-U. acknowledges support of the FPI fellowship from the Spanish MICINN. R.M. acknowledges support of Marie Curie and NEST fellowships. C.G.-B. and F.J.G.-V. acknowledge the European Research Council (ERC-2011-AdG, Proposal No. 290981). C.G.-B., E.M., and F.J.G.-V. acknowledge the Spanish MINECO (Contract No. MAT2011-28581-C02-01). C.G.-B. acknowledges support of the FPU fellowship from the Spanish MECD. I.P.R., T.H. and S.I.B. acknowledge financial support for this work from the Danish Council for Independent Research (the FTP project ANAP, Contract No. 09-072949) and from the European Research Council, Grant No. 341054 (PLAQNAP). Y.A. acknowledges the support of RYC-2011-08471 fellowship from MICINN. We thank Luis Martin-Moreno and Cesar E. García for fruitful discussions, Jana M. Say and Louise J. Brown for providing the ND solution, and Ioannis Tsioutsios for support with the AFM manipulation technique.This is the final published version. It first appeared at http://www.nature.com/ncomms/2015/150807/ncomms8883/full/ncomms8883.html

A clinical case of neonatal diabetes caused by INS gene mutation

Neonatal diabetes mellitus (NDM) is a severe endocrine pathology diagnosed in children during the first months of life. It comprises rare (1:300 000–1:400 000 newborns) metabolic disorders with postnatal pancreatic β-cell dysfunction, manifested by hyperglycaemia and hypoinsulinaemia. It is currently established that molecular genetic diagnosis of neonatal diabetes forms can influence treatment and prognosis. Interestingly, most identified mutations in the insulin gene are not inherited, but are sporadic. There is evidence that, in addition to heterozygous INS mutations, NDM can be caused by homozygous or compound-heterozygous mutations. The present article presents the clinical case of a girl with NDM associated with an INS gene mutation. INS gene mutations cause permanent diabetes and require children to undergo genetic examination, especially patients with type 1 diabetes in the absence of antibodies. Currently, there are no data that allow to determine a phenotypic and genotypic ‘portrait’ of NDM forms or to explain the factors determining their occurrence. Further studies of clinical cases of neonatal diabetes are therefore required to determine the characteristics of NDM subtypes with subsequent disease prognosis

Sensitivity enhancement of nanoplasmonic sensors in low refractive index substrates

9 páginas, 4 figuras, 1 tabla.-- OCIS codes: (130.6010) Sensors; (240.6680) Surface Plasmons; (310.6845) Thin film devices and applications; (260.3910) Metal opticsMetal films perforated by nanoholes constitute a powerful platform for surface plasmon resonance biosensing. We find that the refractive index sensitivity of nanohole arrays increases if their resonance is red-shifted by increasing the separation distance between holes. However, an additional sensitivity enhancement occurs if the nanohole sensors are manufactured on low index substrates, despite the fact such substrates significantly blue-shift the resonance. We find a ~40% higher bulk refractive index sensitivity for a system of ~100 nm holes in 20 nm gold films fabricated on Teflon substrates (n=1.32) compared to the case when conventional glass substrates (n=1.52) are used. A similar improvement is observed for the case when a thin layer of dielectric material is deposited on the samples. These results can be understood by considering the electric field distribution induced by the so-called antisymmetric surface plasmon polariton in the thin gold films.B. Brian and M. Käll acknowledge the financial support from Swedish Research Council and Swedish Foundation for Strategic Research. B. Sepulveda and L. M. Lechuga acknowledge the financial support from M. Botin Foundation.Peer reviewe

Spectral tunability of a plasmonic antenna with a dielectric nanocrystal.

We show that the positioning of a nanometer length scale dielectric object, such as a diamond nanocrystal, in the vicinity of a gold bowtie nanoantenna can be used to tune the plasmonic mode spectrum on the order of a linewidth. We further show that the intrinsic luminescence of gold enhanced in the presence of nanometer-scale roughness couples efficiently to the plasmon mode and carries the same polarization anisotropy. Our findings have direct implications for cavity quantum electrodynamics related applications of hybrid antenna-emitter complexes

Optically controlled interparticle distance tuning and welding of single gold nanoparticle pairs by photochemical metal deposition

We report on the in-situ controlled tuning of the particle gap in single pairs of gold nanodisks by photochemical metal deposition. The optically induced growth of nanodisk dimers fabricated by electron beam lithography leads to a decrease of the interparticle gap width down to 0 nm. Due to the increasing particle size and stronger plasmonic coupling, a smooth redshift of the localized surface plasmon (LSP) resonances is observed in such particle pairs during the growth process. The interparticle gap width, and hence the LSP resonance, can be tuned to any desired spectral position. The experimental results we obtain with this nanoscale fabrication technique are well described by the so-called plasmon ruler equation. Consequently, both the changes in particle diameter as well as in gap width can be characterized in-situ via far-field read-out of the optical properties of the dimers

Photochemical tuning of plasmon resonances in single gold nanoparticles

We report on the spectrally controlled photochemical tuning of the size, shape, and localized surface plasmon resonances of individual gold nanoparticles. Single spheres, extracted from a colloidal solution, and elongated nanodiscs, fabricated by electron beam lithography, were exposed to a gold salt solution while being illuminated one by one by a focused 532-nm laser beam. The photochemical reduction of tetrachloroaureate complexes, followed by the subsequent agglomeration of gold atoms at the particle surface, lead to a well-controlled single-particle growth. This fully in situ monitored method allows us to tune the radius of single spheres as well as the aspect ratio of single ellipsoidal particles, enabling spectral control of their respective localized surface plasmon resonances