Sb-, Dy-, and Eu-doped oxyfluoride silicate glasses for light emitting diodes

International audienceA series of Sb-, Dy-, and Eu-doped oxyfluoride silicate glasses for light emitting diodes (LEDs) applications were prepared via the melt-quenching method, and studied by a) photoluminescence emission and excitation spectra, b) decay curves, c) Commission Internationale de L'Eclairage (CIE) chromaticity coordinates, and d) correlated color temperatures (CCTs). We discover the energy transfer from Sb3+ to Dy3+ ions occurs in Sb/Dy co-doped glass. We also find the emission behavior of Sb3+ single doped glass is dependent on the excitation wavelength. Furthermore, the white light emission can be achieved in Sb/Dy/Eu co-doped oxyfluoride silicate glasses under ultraviolet (UV) light excitation. The results presented here demonstrate that the as-prepared Sb/Dy/Eu doped oxyfluoride silicate glasses may serve as a potential candidate for LEDs-based lightin

The Application of Infrared Imaging and Optical Coherence Tomography of the Lacrimal Punctum in Patients Undergoing Punctoplasty for Epiphora

Purpose To determine the application of imaging the stenotic lacrimal punctum with infrared photographs and optical coherence tomography (OCT) and to identify characteristics of the lacrimal punctum in patients who benefit from punctoplasty. Design Case-control study. Participants Twenty patients with epiphora who were listed for punctoplasty and 20 healthy controls. Methods Prospectively, 20 patients listed for punctoplasty were asked to rate their epiphora, using the Munk score, before and after punctoplasty. They also underwent preoperative OCT and infrared imaging of the affected punctum. They were divided into 2 groups, depending on whether the epiphora improved, and were compared with 20 healthy controls. Main Outcome Measures Measurements of puncta from infrared and OCT images were obtained along with Munk scores of patient epiphora. Results The infrared image measurements were significantly smaller in those patients whose epiphora improved compared with those whose did not in both the area of the punctal aperture and in the maximum punctal diameter. Additionally, those patients with improvement in epiphora had a significantly smaller preoperative punctal diameter at 100 μm depth on OCT compared with healthy controls; this was not observed in patients whose epiphora failed to improve. There was no significant difference in the punctum diameter among the 3 groups at the punctum surface entrance or at 500 μm depth. Patients with epiphora had a higher tear meniscus within the punctum compared with healthy controls. Conclusions Lacrimal punctum infrared and OCT imaging may be helpful in predicting patients more likely to benefit symptomatically from punctoplasty, with patients with smaller puncta having greater symptomatic improvement. However, the results suggest that inner punctum diameter (not readily measurable by slit-lamp examination), rather than the surface diameter, is correlated with outcome. Additionally, OCT measurements of the tear meniscus height within the punctum may be related to the degree of epiphora

The Clustering of High-Redshift (2.9 ≤\leq z ≤\leq 5.1) Quasars in SDSS Stripe 82

We present a measurement of the two-point autocorrelation function of photometrically-selected, high-$z$ quasars over $\sim$ 100 deg$^2$ on the Sloan Digitial Sky Survey Stripe 82 field. Selection is performed using three machine-learning algorithms, trained on known high-$z$ quasar colors, in a six-dimensional, optical/mid-infrared color space. Optical data from the Sloan Digitial Sky Survey is combined with overlapping deep mid-infrared data from the \emph{Spitzer} IRAC Equatorial Survey and the \emph{Spitzer}-HETDEX Exploratory Large-area survey. The selected quasar sample consists of 1378 objects and contains both spectroscopically-confirmed quasars and photometrically-selected quasar candidates. These objects span a redshift range of $2.9 \leq z \leq 5.1$ and are generally fainter than $i=20.2$; a regime which has lacked sufficient number density to perform autocorrelation function measurements of photometrically-classified quasars. We compute the angular correlation function of these data, marginally detecting quasar clustering. We fit a single power-law with an index of $\delta = 1.39 \pm 0.618$ and amplitude of $\theta_0 = 0.71 \pm 0.546$ arcmin. A dark-matter model is fit to the angular correlation function to estimate the linear bias. At the average redshift of our survey ($\langle z \rangle = 3.38$) the bias is $b = 6.78 \pm 1.79$. Using this bias, we calculate a characteristic dark-matter halo mass of 1.70--9.83$\times 10^{12}h^{-1} M_{\odot}$. Our bias estimate suggests that quasar feedback intermittently shuts down the accretion of gas onto the central super-massive black hole at early times. If confirmed, these results hint at a level of luminosity dependence in the clustering of quasars at high-$z$.Comment: 23 Pages, 17 Figure

Initial Results of a Silicon Sensor Irradiation Study for ILC Extreme Forward Calorimetry

Detectors proposed for the International Linear Collider (ILC) incorporate a tungsten sampling calorimeter (`BeamCal') intended to reconstruct showers of electrons, positrons and photons that emerge from the interaction point of the collider with angles between 5 and 50 milliradians. For the innermost radius of this calorimeter, radiation doses at shower-max are expected to reach 100 MRad per year, primarily due to minimum-ionizing electrons and positrons that arise in the induced electromagnetic showers of e+e- `beamstrahlung' pairs produced in the ILC beam-beam interaction. However, radiation damage to calorimeter sensors may be dominated by hadrons induced by nuclear interactions of shower photons, which are much more likely to contribute to the non-ionizing energy loss that has been observed to damage sensors exposed to hadronic radiation. We report here on the results of SLAC Experiment T-506, for which several different types of silicon diode sensors were exposed to doses of radiation induced by showering electrons of energy 3.5-10.6 GeV. By embedding the sensor under irradiation within a tungsten radiator, the exposure incorporated hadronic species that would potentially contribute to the degradation of a sensor mounted in a precision sampling calorimeter. Depending on sensor technology, efficient charge collection was observed for doses as large as 220 MRad.Comment: Talk presented at the International Workshop on Future Linear Colliders (LCWS13), Tokyo, Japan, 11-15 November 201

Characterizing the Occluded Lacrimal Punctum Using Anterior Segment Optical Coherence Tomography.

PURPOSE: Epiphora is sometimes associated with an absent or occluded lacrimal drainage punctum (or puncta). This study uses noninvasive "enhanced depth" anterior segment optical coherence tomography (OCT) to give improved characterization and understanding of absent or fully occluded puncta and the underlying canaliculus. METHODS: Anterior segment spectral domain OCT images were collected prospectively from 9 lower puncta of 6 patients with epiphora and absent or fully occluded puncta, not amenable to dilation in clinic, to see if a canaliculus was visible on OCT imaging below the occluded punctum. RESULTS: An epithelial lined canalicular lumen was visible on OCT in 4 lower eyelid puncta from 2 patients and OCT identified 80% (4/5) of the canaliculi that were located on microscope-assisted punctal exploration. These lumens were seen within 580 μm depth from the eyelid margin surface. A half of the eyes in which a canaliculus was identified on OCT (the 2 eyes in a single patient) had resolution of epiphora following punctoplasty, and the other patient was found to have coexisting nasolacrimal duct stenosis and required later dacryocystorhinostomy. The positive predictive value for identifying a canaliculus on lower eyelid punctal exploration in acquired complete punctal occlusion (excluding the congenital case) was 1, with a negative predictive value of 1. CONCLUSIONS: This study demonstrates that canaliculi can be imaged with OCT where formal access is precluded by an occluded punctum. This noninvasive investigation might help predict the likelihood of successful retrieval of a canaliculus at surgical exploration

Non-contacting techniques for plant drought stress detection

Plant drought stress indicators such as crop water stress index (CWSI), plant motion in the form of covariance of top-projected canopy area (COV_TPCA), leaf water content represented as equivalent water thickness (EWT), and their threshold values for drought stress detection were established from measurements. Performances of these indicators in detecting drought stress of New Guinea Impatiens plants in a controlled environment were evaluated. Analysis of variance (ANOVA) was conducted to compare the timing of drought stress detection by these indicators against the timing of incipient drought stress defined by evapotranspiration (ET) and timing of human visual detection. Statistical analysis was also performed to study the consistency of the threshold values of the indicators in different experiments. ANOVA results showed that the CWSI was the most reliable indicator for early plant drought stress detection. The timing of the drought stress detection from the earliest to the latest was CWSI, EWT and COV_TPCA. While COV_TPCA and EWT were not able to detect drought stress as early as CWSI, ANOVA results indicated that these two indicators were able to detect drought stress no later than visual detection. ANOVA results also showed that there was no significant difference in threshold values of CWSI and COV_TPCA in different experiments, but different cultivars used in the experiments resulted in significant differences in EWT threshold values

Spectroscopy of broad absorption line quasars at 3≲z≲53\lesssim z \lesssim 5 -- I: evidence for quasar winds shaping broad/narrow emission line regions

We present an observational study of 22 broad absorption line quasars (BAL QSOs) at $3\lesssim z \lesssim5$ based on optical/near-IR spectroscopy, aiming to investigate quasar winds and their effects. The near-IR spectroscopy covers the \hb\ and/or \mgii\ broad emission lines (BELs) for these quasars, allowing us to estimate their central black hole (BH) masses in a robust way. We found that our BAL QSOs on average do not have a higher Eddington ratio than that from non-BAL QSOs matched in redshift and/or luminosity. In a subset consisting of seven strong BAL QSOs possessing sub-relativistic BAL outflows, we see the prevalence of large \civ-BEL blueshift ($\sim$3100 km s$^{-1}$) and weak \oiii\ emission (particularly the narrow \oiii$\lambda$5007 component), indicative of nuclear outflows affecting the narrow emission-line (NEL) regions. In another subset consisting of thirteen BAL QSOs having simultaneous observations of \mgii\ and \hb, we found a strong correlation between 3000~\AA\ and 5000~\AA\ monochromatic luminosity, consistent with that from non-BAL QSOs matched in redshift and luminosity; however, there is no correlation between \mgii\ and \hb\ in FWHM, likely due to nuclear outflows influencing the BEL regions. Our spectroscopic investigations offer strong evidence that the presence of nuclear outflows plays an important role in shaping the BEL/NEL regions of these quasars and possibly, regulating the growth of central supermassive black holes (SMBHs). We propose that BEL blueshift and BAL could be different manifestations of the same outflow system viewed at different sightlines and/or phases.Comment: 13 pages, 10 figures. Accepted for publication in Ap