Systems and methods for altering visual acuity

Provided are systems operable to effect a temporary change in a modulation transfer function (MTF) of a target imaging system. The systems include a light source operable to produce light for transient propagation onto at least a portion of the target imaging system, a power source in operative communication with the light source and configured to effect the production of light from the light source, and a transmission unit in operative communication with the light source and configured to propagate the produced light onto at least a portion of the target imaging system. The propagated light is configured for absorbance by the portion of the target imaging system; the absorbance causes an increase in temperature and a change in a refractive index profile of at least the portion of the imaging system. The change in refractive index profile produces a temporary change in the MTF of the imaging system.Board of Regents, University of Texas Syste

Integrating methods for determining length-at-age to improve growth estimates for two large scombrids

Fish growth is commonly estimated from length-at-age data obtained from otoliths. There are several techniques for estimating length-at-age from otoliths including 1) direct observed counts of annual increments; 2) age adjustment based on a categorization of otolith margins; 3) age adjustment based on known periods of spawning and annuli formation; 4) back-calculation to all annuli, and 5) back-calculation to the last annulus only. In this study we compared growth estimates (von Bertalanffy growth functions) obtained from the above five methods for estimating length-at-age from otoliths for two large scombrids: narrow-barred Spanish mackerel (Scomberomorus commerson) and broad-barred king mackerel (Scomberomorus semifasciatus). Likelihood ratio tests revealed that the largest differences in growth occurred between the back-calculation methods and the observed and adjusted methods for both species of mackerel. The pattern, however, was more pronounced for S. commerson than for S. semifasciatus, because of the pronounced effect of gear selectivity demonstrated for S. commerson. We propose a method of substituting length-at-age data from observed or adjusted methods with back-calculated length-at-age data to provide more appropriate estimates of population growth than those obtained with the individual methods alone, particularly when faster growing young fish are disproportionately selected for. Substitution of observed or adjusted length-at-age data with back-calculated length-at-age data provided more realistic estimates of length for younger ages than observed or adjusted methods as well as more realistic estimates of mean maximum length than those derived from backcalculation methods alone

Demographic characteristics of exploited tropical lutjanids: a comparative analysis

Demographic parameters from seven exploited coral reef lutjanid species were compared as a case study of the implications of intrafamily variation in life histories for multispecies harvest management. Modal lengths varied by 4 cm among four species (Lutjanus fulviflamma, L. vitta, L. carponotatus, L. adetii), which were at least 6 cm smaller than the modal lengths of the largest species (L. gibbus, Symphorus nematophorus, Aprion virescens). Modal ages, indicating ages of full selection to fishing gear, were 10 years or less for all species, but maximum ages ranged from 12 (L. gibbus) to 36 years (S. nematophorus). Each species had a unique growth pattern, with differences in length-at-age and mean asymptotic fork length (L∞), but smaller species generally grew fast during the first 1–2 years of life and larger species grew more slowly over a longer period. Total mortality rates varied among species; L. gibbus had the highest mortality and L. fulviflamma, the lowest mortality. The variability in life history strategies of these tropical lutjanids makes generalizations about lutjanid life histories difficult, but the fact that all seven had characteristics that would make them particularly vulnerable to fishing indicates that harvest of tropical lutjanids should be managed with caution

Spotsize Effects on Guinea Pig Skin Following Pulsed Irradiation

Laser irradiation parameters such as wavelength, irradiance (W/cm2), and pulse duration have been clearly shown to influence the extent to which tissue is damaged. The careful choice of these parameters can result in confining laser injury to specific targets in tissue. Spotsize, a parameter not commonly appreciated in the application of lasers to medicine and surgery, has been shown, in this study, to contribute to the ultimate outcome of laser effects in tissue. A series of histological events occurring in the skin are demonstrated to be directly related to the effects of spotsize on tissue at a fixed exposure time and wavelength. Many of these changes could contribute to unwanted adverse effects, such as scarring, which occur following certain laser therapies

Laser treatment of cutaneous vascular lesions

Methods for treating maladies such as cutaneous vascular lesions. A patient in need of vascular lesion treatment is identified. A hyperosmotic agent is administered to a region adjacent the lesion. Blood flow velocity is slowed within the region using the hyperosmotic agent, and the lesion is exposed to laser radiation.Board of Regents, University of Texas Syste

An Electrochemical Study of Frustrated Lewis Pairs: A Metal-free Route to Hydrogen Oxidation

[Image: see text] Frustrated Lewis pairs have found many applications in the heterolytic activation of H(2) and subsequent hydrogenation of small molecules through delivery of the resulting proton and hydride equivalents. Herein, we describe how H(2) can be preactivated using classical frustrated Lewis pair chemistry and combined with in situ nonaqueous electrochemical oxidation of the resulting borohydride. Our approach allows hydrogen to be cleanly converted into two protons and two electrons in situ, and reduces the potential (the required energetic driving force) for nonaqueous H(2) oxidation by 610 mV (117.7 kJ mol(–1)). This significant energy reduction opens routes to the development of nonaqueous hydrogen energy technology

Novel B(Ar')2(Ar'') hetero-tri(aryl)boranes: a systematic study of Lewis acidity

A series of homo- and hetero-tri(aryl)boranes incorporating pentafluorophenyl, 3,5-bis(trifluoromethyl)phenyl, and pentachlorophenyl groups, four of which are novel species, have been studied as the acidic component of frustrated Lewis pairs for the heterolytic cleavage of H2. Under mild conditions eight of these will cleave H2; the rate of cleavage depending on both the electrophilicity of the borane and the steric bulk around the boron atom. Electrochemical studies allow comparisons of the electrophilicity with spectroscopic measurements of Lewis acidity for different series of boranes. Discrepancies in the correlation between these two types of measurements, combined with structural characterisation of each borane, reveal that the twist of the aryl rings with respect to the boron-centred trigonal plane is significant from both a steric and electronic perspective, and is an important consideration in the design of tri(aryl)boranes as Lewis acids

Exploring structural and electronic effects in three isomers of tris{bis(trifluoromethyl)phenyl}borane: Towards the combined electrochemical-frustrated Lewis pair activation of H2

Three structural isomers of tris{bis(trifluoromethyl)phenyl}borane have been studied as the acidic com- ponent of frustrated Lewis pairs. While the 3,5-substituted isomer is already known to heterolytically cleave H2 to generate a bridging-hydride; ortho-substituents in the 2,4- and 2,5-isomers quench such reactivity through electron donation into the vacant boron pz orbital and steric blocking of the boron centre; as shown by electrochemical, structural and computational studies. Electrochemical studies of the corresponding borohydrides identify that the two-electron oxidation of terminal-hydrides occurs at more positive potentials than observed for [HB(C6F5)3]−, while the bridging-hydride oxidizes at a higher poten- tial still, comparable to that of free H2

A Hubble Space Telescope survey for novae in M87 – III. Are novae good standard candles 15 d after maximum brightness?

Ten weeks of daily imaging of the giant elliptical galaxy M87 with the Hubble Space Telescope (HST) has yielded 41 nova light curves of unprecedented quality for extragalactic cataclysmic variables. We have recently used these light curves to demonstrate that the observational scatter in the so-called maximum-magnitude rate of decline (MMRD) relation for classical novae is so large as to render the nova-MMRD useless as a standard candle. Here, we demonstrate that a modified Buscombe–de Vaucouleurs hypothesis, namely that novae with decline times t_2 > 10 d converge to nearly the same absolute magnitude about two weeks after maximum light in a giant elliptical galaxy, is supported by our M87 nova data. For 13 novae with daily sampled light curves, well determined times of maximum light in both the F606W and F814W filters, and decline times t_2 > 10 d we find that M87 novae display M_(606W,15) = −6.37 ± 0.46 and M_(814W,15) = −6.11 ± 0.43. If very fast novae with decline times t_2 < 10 d are excluded, the distances to novae in elliptical galaxies with stellar binary populations similar to those of M87 should be determinable with 1σ accuracies of ± 20 per cent with the above calibrations

Mechanisms of activation of mouse and human enteroendocrine cells by nutrients

AstraZeneca, Wellcome Trust, Bowel and Cancer Research, Barts and the London Charity