1,992 research outputs found
Quantum-dot based nanothermometry in optical plasmonic recording media
We report on the direct experimental determination of the temperature increment caused by laser irradiation in a optical recording media constituted by a polymeric film in which gold nanorods have been incorporated. The incorporation of CdSe quantum dots in the recording media allowed for single beam thermal reading of the on-focus temperature from a simple analysis of the two-photon excited fluorescence of quantum dots. Experimental results have been compared with numerical simulations revealing an excellent agreement and opening a promising avenue for further understanding and optimization of optical writing processes and media
Ins1 (Cre) knock-in mice for beta cell-specific gene recombination.
AIMS/HYPOTHESIS: Pancreatic beta cells play a central role in the control of glucose homeostasis by secreting insulin to stimulate glucose uptake by peripheral tissues. Understanding the molecular mechanisms that control beta cell function and plasticity has critical implications for the pathophysiology and therapy of major forms of diabetes. Selective gene inactivation in pancreatic beta cells, using the Cre-lox system, is a powerful approach to assess the role of particular genes in beta cells and their impact on whole body glucose homeostasis. Several Cre recombinase (Cre) deleter mice have been established to allow inactivation of genes in beta cells, but many show non-specific recombination in other cell types, often in the brain.
METHODS: We describe the generation of Ins1 (Cre) and Ins1 (CreERT2) mice in which the Cre or Cre-oestrogen receptor fusion protein (CreERT2) recombinases have been introduced at the initiation codon of the Ins1 gene.
RESULTS: We show that Ins1 (Cre) mice induce efficient and selective recombination of floxed genes in beta cells from the time of birth, with no recombination in the central nervous system. These mice have normal body weight and glucose homeostasis. Furthermore, we show that tamoxifen treatment of adult Ins1 (CreERT2) mice crossed with Rosa26-tdTomato mice induces efficient recombination in beta cells.
CONCLUSIONS/INTERPRETATION: These two strains of deleter mice are useful new resources to investigate the molecular physiology of pancreatic beta cells
Absorption efficiency of gold nanorods determined by quantum dot fluorescence thermometry
In this work quantum dot fluorescence thermometry, in combination with double-beam confocal microscopy, has been applied to determine the thermal loading of gold nanorods when subjected to an optical excitation at the longitudinal surface plasmon resonance. The absorbing/heating efficiency of low (â3) aspect ratio gold nanorods has been experimentally determined to be close to 100%, in excellent agreement with theoretical simulations of the extinction, absorption, and scattering spectra based on the discrete dipole approximation
Optical Interferometry of early-type stars with PAVO@CHARA. I. Fundamental stellar properties
We present interferometric observations of 7 main-sequence and 3 giant stars
with spectral types from B2 to F6 using the PAVO beam combiner at the CHARA
array. We have directly determined the angular diameters for these objects with
an average precision of 2.3%. We have also computed bolometric fluxes using
available photometry in the visible and infrared wavelengths, as well as
space-based ultraviolet spectroscopy. Combined with precise \textit{Hipparcos}
parallaxes, we have derived a set of fundamental stellar properties including
linear radius, luminosity and effective temperature. Fitting the latter to
computed isochrone models, we have inferred masses and ages of the stars. The
effective temperatures obtained are in good agreement (at a 3% level) with
nearly-independent temperature estimations from spectroscopy. They validate
recent sixth-order polynomial (B-V)- empirical relations
\citep{Boyajian2012a}, but suggest that a more conservative third-order
solution \citep{vanBelle2009} could adequately describe the
(V-K)- relation for main-sequence stars of spectral type A0 and
later. Finally, we have compared mass values obtained combining surface gravity
with inferred stellar radius (\textit{gravity mass}) and as a result of the
comparison of computed luminosity and temperature values with stellar
evolutionary models (\textit{isochrone mass}). The strong discrepancy between
isochrone and gravity mass obtained for one of the observed stars,
\,Lyr, suggests that determination of the stellar atmosphere parameters
should be revised.Comment: 13 pages, 9 figures, accepted for publication in MNRA
Flexibility I-deals and prosocial motives: a trickle-down perspective
Growing concerns of maintaining the best talent have contributed to the rising number of idiosyncratic deals (i-deals) at the workplace. I-deals refer to the personalised work arrangements between employees and their employers where the terms benefit both parties. Despite the acknowledgment that supervisors are key in creating i-deals, research to date has overlooked their role. Drawing on prosocial motives and social learning theory, we explore an overall model of what triggers employee flexibility i-deals and the consequences of such i-deals on employee outcomes. In so doing, we explore one of the key yet untested assumptions of i-deals theory: that they are intended to be mutually beneficial. We investigate our model with matched supervisor â employee data (nâ=â186) collected in El Salvador and Chile. Findings reveal that there is a positive association between supervisorsâ prosocial motives and employeesâ flexibility i-deals. Moreover, prosocial motives of supervisors trickle-down and shape employeesâ functioning at work (i.e. work performance and deviant behaviours) and lead them to be more prosocially motivated through employeesâ flexibility i-deals
'It's a Form of Freedom': The experiences of people with disabilities within equestrian sport
This paper explores the embodied, gendered experiences of disabled horseâriders. Drawing on data from five inâdepth interviews with paradressage riders, the ways in which their involvement in elite disability sport impacts upon their sense of identity and confidence are explored, as well as the considerable health and social benefits that this involvement brings. Social models of disability are employed and the shortcomings of such models, when applied to disability sport, are highlighted. The data presented here demonstrates the necessity of seeing disability sport as an embodied experience and acknowledging the importance of impairment to the experiences of disabled athletes. Living within an impaired body is also a gendered experience and the implications of this when applied to elite disability sport are considered
Anisotropic lattice changes in femtosecond laser inscribed Nd3+:MgO:LiNbO3 optical waveguides
We report on the fabrication and microspectroscopy imaging of femtosecond laser written
double-filament based Nd3+ :MgO:LiNbO3 optical waveguides. The waveguiding high
refractive-index regions are identified by blueshifts of the Nd3+ ion fluorescence lines with no
deterioration in the fluorescence efficiency, whereas filamentary low-index regions are identified by
both a Nd3+ line redshift and a fluorescence efficiency reduction. The lattice structural
micromodifications at the origin of both waveguide formation and Nd3+ fluorescence changes have
been investigated by means of confocal micro-Raman experiments. We have found that the direct
laser written filaments are mainly constituted by a large density of defects, together with a marked
axial compression perpendicular to the filaments ïżœalong the optical c-axisïżœ. Conversely, the
high-index waveguiding regions are characterized by a pronounced anisotropic dilatation of the
LiNbO3 lattice xy-planes
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