Pixelwise immersion factor calibration for underwater hyperspectral imaging instruments.

In situ spectral reflectance initially captured at high spatial resolution with underwater hyperspectral imaging (UHI) is effective for classification and quantification in oceanic biogeochemical studies; however, the measured spectral radiance is rarely used as an absolute quantity due to challenges in calibration of UHI instruments. In this paper, a commercial UHI instrument was calibrated for radiometric flat field response and pixelwise immersion effect to support in situ measurement of absolute spectral radiance. The radiometric and immersion factor calibrations of the UHI instrument were evaluated quantitatively through comparative experiments with a spectroradiometer and a spectrometer.

Neural network approach for correction of multiple scattering errors in the LISST-VSF instrument.

The LISST-VSF is a commercially developed instrument used to measure the volume scattering function (VSF) and attenuation coefficient in natural waters, which are important for remote sensing, environmental monitoring and underwater optical wireless communication. While the instrument has been shown to work well at relatively low particle concentration, previous studies have shown that the VSF obtained from the LISST-VSF instrument is heavily influenced by multiple scattering in turbid waters. High particle concentrations result in errors in the measured VSF, as well as the derived properties, such as the scattering coefficient and phase function, limiting the range at which the instrument can be used reliably.

Efficient Monte Carlo simulation reveals significant multiple scattering errors in underwater angular scattering measurements.

Multiple scattering can severely affect the accuracy of optical instrumentation. Variance reduction methods have been implemented to improve a Monte Carlo model developed to simulate volume scattering functions measured by LISST-VSF instruments. The implemented methods can result in more than a tenfold increase in efficiency.

Analysis of multiple scattering errors in LISST-VSF volume scattering function measurements using Monte Carlo simulations and experimental data.

A Monte Carlo algorithm has been developed to investigate the effects of multiple scattering on the volume scattering function measured by the LISST-VSF instrument. The developed algorithm is compared to experimental results obtained from bench-top measurements using 508nm spherical polystyrene beads and Arizona test dust as scattering agents. The Monte Carlo simulation predicts measured volume scattering functions at all concentrations.

In situ measurements of the volume scattering function with LISST-VSF and LISST-200X in extreme environments: evaluation of instrument calibration and validity.

The LISST-VSF and LISST-200X are commercial instruments made available in recent years, enabling underwater measurements of the volume scattering function, which has not been routinely measured in situ due to lack of instrumentation and difficulty of measurement. Bench-top and in situ measurements have enabled absolute calibration of the instruments and evaluation of instrument validity ranges, even at environmental extremes such as the clear waters at the North Pole and turbid glacial meltwaters. Key considerations for instrument validity ranges are ring detector noise levels and multiple scattering.

Validation of OMI-DOAS total ozone column amounts against ground-based measurements at an African equatorial belt site.

The total ozone column amount (TOCA) values from the Ozone Monitoring Instrument (OMI) derived from OMI/Aura ozone (O3) differential optical absorption spectroscopy (DOAS) V003 (OMDOAO3) have been validated against the ground-based TOCA values derived from Dobson and the Norwegian Institute for Air Research UV measurements in Kampala (0.31º N, 32.58º E, 1200 m), Uganda, for the period between 2005 and 2018.

Cherenkov Luminescence Imaging for Assessment of Radioactive Plaque Position in Brachytherapy of Uveal Melanoma: An In Vivo Feasibility Study.

Purpose: To study the feasibility of using Cherenkov luminescence imaging (CLI) to evaluate and document ruthenium-106 plaque position during brachytherapy of uveal melanoma.

Methods: Ruthenium-106 decays by emitting high-energy beta particles. When the electrons pass through the eye, Cherenkov radiation generates a faint light that can be captured by highly sensitive cameras.

Testing Fluorescence Lifetime Standards using Two-Photon Excitation and Time-Domain Instrumentation: Fluorescein, Quinine Sulfate and Green Fluorescent Protein.

It is essential for everyone working with experimental science to be certain that their instruments produce reliable results, and for fluorescence lifetime experiments, information about fluorescence lifetime standards is crucial. A large part of the literature on lifetime standards dates back to the 1970s and 1980s, and the use of newer and faster measuring devices may deem these results unreliable. We have tested the three commonly used fluorophores fluorescein, quinine sulfate and green fluorescent protein for their suitability to serve as lifetime standards, especially to be used with two-photon excitation measurements in the time-domain.

Reading from an iPad or from a book in bed: the impact on human sleep. A randomized controlled crossover trial.

Objective: To objectively and subjectively compare whether reading a story for 30 min from an iPad or from a book in bed prior to sleep will differentially affect sleep.

Methods: Sixteen students (12 females, mean age 25.1 ± 2.

Blue-blocking glasses as additive treatment for mania: a randomized placebo-controlled trial.

Objectives: The discovery of the blue lightsensitive retinal photoreceptor responsible for signaling daytime to the brain suggested that light to the circadian system could be inhibited by using blue-blocking orange tinted glasses. Blue-blocking (BB) glasses are a potential treatment option for bipolar mania. We examined the effectiveness of BB glasses in hospitalized patients with bipolar disorder in a manic state.

Aerosol optical properties in Northern Norway and Svalbard.

We present comparisons between estimates of the aerosol optical thickness and the Ångström exponent in Northern Norway and Svalbard based on data from AERONET (Aerosol Robotic Network) stations at Andenes (69.28°N, 16.01°E, 379 m altitude) and Hornsund (77.

Chlorophyll a fluorescence lifetime reveals reversible UV-induced photosynthetic activity in the green algae Tetraselmis.

The fluorescence lifetime is a very useful parameter for investigating biological materials on the molecular level as it is mostly independent of the fluorophore concentration. The green alga Tetraselmis blooms in summer, and therefore its response to UV irradiation is of particular interest. In vivo fluorescence lifetimes of chlorophyll a were measured under both normal and UV-stressed conditions of Tetraselmis.

Validation of ozone monitoring instrument ultraviolet index against ground-based UV index in Kampala, Uganda.

The Ozone Monitoring Instrument (OMI) overpass solar ultraviolet (UV) indices have been validated against the ground-based UV indices derived from Norwegian Institute for Air Research UV measurements in Kampala (0.31° N, 32.58° E, 1200 m), Uganda for the period between 2005 and 2014.

Aerosol optical properties and precipitable water vapor column in the atmosphere of Norway.

Between February 2012 and April 2014, we measured and analyzed direct solar radiances at a ground-based station in Bergen, Norway. We discovered that the spectral aerosol optical thickness (AOT) and precipitable water vapor column (PWVC) retrieved from these measurements have a seasonal variation with highest values in summer and lowest values in winter. The highest value of the monthly median AOT at 440 nm of about 0.

Blocking blue light during mania - markedly increased regularity of sleep and rapid improvement of symptoms: a case report.

Objective: Available pharmacological treatment of mania is insufficient. Virtual darkness therapy (blue light-blocking treatment by means of orange-tinted glasses) is a promising new treatment option for mania. The basis for this might be the recently identified blue light-sensitive retinal photoreceptor, which is solely responsible for light stimulus to the circadian master clock.

Aerosols in coastal and inland areas in the equatorial African belt.

Aerosols affect the climate directly through absorption and reflection of sunlight back to space and indirectly by acting as cloud condensation nuclei. This paper is based on more than three decades of satellite data (1979-1994 and 1996-2012) from total ozone mapping spectrometer (TOMS) and ozone monitoring instrument (OMI), which have provided measurements of backscattered radiances in the wavelength range from 331 to 380 nm. These data have been used to determine the aerosol climatology and to investigate the influence of the aerosol index (AI) on the ultraviolet index (UVI) in coastal land areas in Serrekunda (13.

Testing fluorescence lifetime standards using two-photon excitation and time-domain instrumentation: rhodamine B, coumarin 6 and lucifer yellow.

Having good information about fluorescence lifetime standards is essential for anyone performing lifetime experiments. Using lifetime standards in fluorescence spectroscopy is often regarded as a straightforward process, however, many earlier reports are limited in terms of lifetime concentration dependency, solvents and other technical aspects. We have investigated the suitability of the fluorescent dyes rhodamine B, coumarin 6, and lucifer yellow as lifetime standards, especially to be used with two-photon excitation measurements in the time-domain.

Infectious salmon anemia (ISA) virus: infectivity in seawater under different physical conditions.

Infectious salmon anemia (ISA) virus (genus Isavirus, family Orthomyxoviridae), present in all major salmon producing countries, is the causative agent for a serious and commercially important disease affecting Atlantic Salmon Salmo salar. Nearly all ISA outbreaks occur in the marine production phase and knowledge about survival time for ISA virions in seawater is crucial for an adequate strategy to combat the disease. To acquire knowledge about this important factor, a study of ISA virus exposed to four different physical conditions was carried out.

Comparison of ground-based measurements of solar UV radiation at four sites on the Tibetan Plateau.

We compare results for the UV index (UVI), the total ozone column (TOC), and the radiation modification factor (RMF, being 1 in the absence of clouds and aerosols) at four sites on the Tibetan Plateau. The results were obtained by analyzing ground measurements by multichannel moderate-bandwidth filter instruments for the period July 2008-September 2010, and radiative transfer modeling was used to aid the interpretation of the results. The highest UVI of 20.

Stokes scattering matrix for human skin.

We use a layered model of normal human skin based on size distributions of polydisperse spherical particles and their complex refractive indices to compute the Stokes scattering matrix at wavelengths in the visible spectral band. The elements of the Stokes scattering matrix are required in a polarized radiative transfer code for a coupled air-tissue system to compute the polarized reflectance and examine how it is dependent on the vertical structure of the inherent optical properties of skin, including the phase matrix. Thus, the elements of the Stokes scattering matrix can be useful for investigating polarization-dependent light propagation in turbid optical media, such as human skin tissue.

Bidirectional reflectance distribution function of Spectralon white reflectance standard illuminated by incoherent unpolarized and plane-polarized light.

A Lambert surface would appear equally bright from all observation directions regardless of the illumination direction. However, the reflection from a randomly scattering object generally has directional variation, which can be described in terms of the bidirectional reflectance distribution function (BRDF). We measured the BRDF of a Spectralon white reflectance standard for incoherent illumination at 405 and 680 nm with unpolarized and plane-polarized light from different directions of incidence.

Optical transfer diagnosis of pigmented lesions.

Background: Optical transfer diagnosis is a novel melanoma detection system that uses morphologic-physiologic mapping.

Objective: To further evaluate the potential of optical transfer diagnosis for distinguishing benign from malignant pigmented melanocytic neoplasms.

Methods And Materials: Ninety-four patients with pigmented lesions suggestive of melanoma were referred for optical transfer diagnosis.

Optical transfer diagnosis of pigmented lesions: a pilot study.

Objective: To evaluate the potential of a novel imaging technology, optical transfer diagnosis (OTD), for differentiation of benign from malignant pigmented melanocytic lesions.

Design: Patients with pigmented lesions suspicious for melanoma were referred for OTD. After scanning, lesions were biopsied for histopathologic examination, each by two separate dermatopathologists.

Protection from phototoxic injury during surgery and endoscopy in erythropoietic protoporphyria.

Erythropoietic protoporphyria is an inherited condition characterized by pronounced solar photosensitivity and in a minority of patients severe liver disease that necessitates liver transplantation for survival. Phototoxic injury to abdominal organs and skin has been reported in several cases of liver transplantation surgery, including a few transplants in which protective light filters were used. This study discusses the optimal characteristics of light filters used during liver transplantation surgery.

Parameterization of the inherent optical properties of Murchison Bay, Lake Victoria.

Lake Victoria, Africa's largest freshwater lake, suffers greatly from negative changes in biomass of species of fish and also from severe eutrophication. The continuing deterioration of Lake Victoria's ecological functions has great long-term consequences for the ecosystem benefits it provides to the countries bordering its shores. However, knowledge about temporal and spatial variations of optical properties and how they relate to lake constituents is important for a number of reasons such as remote sensing, modeling of underwater light fields, and long-term monitoring of lake waters.