3,049 research outputs found
Extended depth of focus intraocular lens: Chromatic performance
We describe a first-and-second-diffractive-order intraocular lens ((1st,2nd)DIOL) within the class of hybrid refractive-diffractive designs for intraocular lenses (IOLs) and analyse its properties of focus extension and compensation of longitudinal chromatic aberration (LCA), particularly for lenses with low addition. Power, energy efficiency and their wavelength dependence are extended from monofocal IOL and conventional bifocal zeroth-and-first-diffractive-order IOL ((0th,1st)DIOL) to (1st,2nd)DIOL of low addition. Compensation of LCA is experimentally assessed in optical bench through the through-focus energy efficiency of three Tecnis IOLs with red, green and blue illuminations: ZA9003 (monofocal), ZKB00 (bifocal (0th,1st)DIOL with + 2.75 D add) and Symfony ZXR00. We prove Tecnis Symfony ZXR00 IOL can be considered an example of (1st,2nd)DIOL design of low addition, with LCA compensation in both the distance and intermediate foci, whereas the bifocal (0th,1st)DIOL does not compensate in the distance focus. However, the energy efficiency of (1st,2nd)DIOL for wavelengths other than the design wavelength is markedly more asymmetric.Postprint (published version
An atlas of Calcium triplet spectra of active galaxies
We present a spectroscopic atlas of active galactic nuclei covering the
region around the 8498, 8542, 8662 Calcium triplet (CaT) lines. The sample
comprises 78 objects, divided into 43 Seyfert 2s, 26 Seyfert 1s, 3 Starburst
and 6 normal galaxies. The spectra pertain to the inner ~300 pc in radius, and
thus sample the central kinematics and stellar populations of active galaxies.
The data are used to measure stellar velocity dispersions (sigma_star) both
with cross-correlation and direct fitting methods. These measurements are found
to be in good agreement with each-other and with those in previous studies for
objects in common. The CaT equivalent width is also measured. We find average
values and sample dispersions of W_CaT of 4.6+/-2.0, 7.0 and 7.7+/-1.0
angstrons for Seyfert 1s, Seyfert 2s and normal galaxies, respectively. We
further present an atlas of [SIII]\lambda 9069 emission line profiles for a
subset of 40 galaxies. These data are analyzed in a companion paper which
addresses the connection between stellar and Narrow Line Region kinematics, the
behaviour of the CaT equivalent width as a function of sigma_star, activity
type and stellar population properties.Comment: 18 pages, 10 figures, accepted for publication in MNRA
Standards for Proficiencies for Instruction Librarians and Coordinators
As the role of instruction and information literacy continues to grow in the academic library, librarians are faced with a need to develop a more focused set of skills to teach effectively in library instruction programs. At the same time, many libraries struggle to offer meaningful training and professional development to improve instruction, especially without a set of established standards for what makes a good instructor. This document is intended to help instruction librarians define and gain the skills needed to be excellent teachers in library instruction programs and to foster collaborations necessary to create and improve information literacy programs.
In many academic libraries, instruction librarians also serve as coordinators of instructional services and as instructional leaders in their organization. In addition to proficiencies needed for librarians with teaching responsibilities are the skills required for instruction coordinators to manage programs. They also must operate effectively at all levels of the academic organization in order to implement broad-reaching curriculum-integrated information literacy programs
Standards for Proficiencies for Instruction Librarians and Coordinators
As the role of instruction and information literacy continues to grow in the academic library, librarians are faced with a need to develop a more focused set of skills to teach effectively in library instruction programs. At the same time, many libraries struggle to offer meaningful training and professional development to improve instruction, especially without a set of established standards for what makes a good instructor. This document is intended to help instruction librarians define and gain the skills needed to be excellent teachers in library instruction programs and to foster collaborations necessary to create and improve information literacy programs.
In many academic libraries, instruction librarians also serve as coordinators of instructional services and as instructional leaders in their organization. In addition to proficiencies needed for librarians with teaching responsibilities are the skills required for instruction coordinators to manage programs. They also must operate effectively at all levels of the academic organization in order to implement broad-reaching curriculum-integrated information literacy programs
Quantitative Changes in Biofilms of a Seawater Tubular Heat Exchanger Subjected to Electromagnetic Fields Treatment
Biofilms adhesion is one of the more important cost
of industries plants on wide world, which use to water for cooling
heat exchangers or are in contact with water. This study evaluated
the effect of Electromagnetic Fields on biofilms in tubular heat
exchangers using seawater cooling. The results showed an up to 40%
reduction of the biofilm thickness compared to the untreated control
tubes. The presence of organic matter was reduced by 75%, the
inorganic mater was reduced by 87%, and 53% of the dissolved solids
were eliminated. The biofilm thermal conductivity in the treated tube
was reduced by 53% as compared to the control tube. The hardness
in the effluent during the experimental period was decreased by 18%
in the treated tubes compared with control tubes. Our results show
that the electromagnetic fields treatment has a great potential in the
process of removing biofilms in heat exchanger
Energy balance in apodized diffractive multifocal intraocular lenses
Postprint (published version
Energy Distribution between Distance and Near Images in Apodized Diffractive Multifocal Intraocular Lenses
Postprint (published version
Clinical assessment of chromatic aberration in phakic and pseudophakic eyes using a simple autorefractor
We describe a psychophysical method and a simple setup – an autorefractor with a Scheiner disc, sequentially illuminated with red and blue lights – for the clinical assessment of the longitudinal chromatic aberration (LCA) in phakic and pseudophakic patients. This method applies to the unaccommodated eye, even in the presence of positive or negative refractive errors and astigmatism. It measures the chromatic difference of refraction as an estimate of LCA. We built a proof of concept from inexpensive and off-the-shelf optomechanical components with which we obtained the preliminary clinical results presented in the paper. We considered one control group of phakic patients and three groups of pseudophakic patients with monofocal implants of different designs and materials. The results, satisfactory and consistent with those reported by other researchers in related works, demonstrate the method and system feasibility.Peer ReviewedPostprint (published version
Maximum tree height in European Mountains decreases above a climate-related elevation threshold
Mountain forests face important threats from global change and spatio-temporal variation in tree height can help to monitor these effects. In this study, we used the Global Ecosystem Dynamics Investigation space-borne laser sensor to examine the relationship between maximum tree height and elevation, and the role of climate, in the main European mountain ranges. We found a piecewise relationship between elevation and maximum tree height in all mountain ranges, supporting the existence of a common breakpoint that marks the beginning of tree development limitations. Temperature and precipitation were identified as the most important drivers of tree height variation. Additionally, we predicted significant upward displacement of the breakpoint for the period 2080-2100 under climate change scenarios, potentially increasing the area without growth limitations for trees. These findings contribute to understanding the impacts of global warming on mountain forest ecosystems and provide insights for their monitoring and management
- …