Observations of Shadow Bands at the Total Solar Eclipse of 16 February 1980

Photoelectric observations of short term light variations (shadow bands) at the 16 Feb. 1980 total solar eclipse have been made using a set of spatially separated PIN diodes. Light variations in a bandpass of 1-500 Hz were detected during the half-minutes preceding and following the total phase. Fourier analysis of the noise spectrum of the variations reveals a sharp drop-off for frequencies about 50 Hz and an overall spectrum quite similar to previously reported power spectra of stellar scintillation. This is consistent with an atmospheric origin for the shadow bands. Cross-correlations between the detector outputs are low, suggesting a short persistence time for the turbulent elements causing the patterns

Organic Alternatives to Quantum Dots for Intraoperative Near-Infrared Fluorescent Sentinel Lymph Node Mapping:

Intraoperative near-infrared (NIR) fluorescence imaging provides the surgeon with real-time image guidance during cancer and other surgeries. We have previously reported the use of NIR fluorescent quantum dots (QDs) for sentinel lymph node (SLN) mapping. However, because of concerns over potential toxicity, organic alternatives to QDs will be required for initial clinical studies. We describe a family of 800 nm organic heptamethine indocyanine-based contrast agents for SLN mapping spanning a spectrum from 775 Da small molecules to 7 MDa nanocolloids. We provide a detailed characterization of the optical and physical properties of these contrast agents and discuss the advantages and disadvantages of each. We present robust methods for the covalent conjugation, purification, and characterization of proteins with tetra-sulfonated heptamethine indocyanines, including mass spectroscopic site mapping of highly substituted molecules. One contrast agent, NIR fluorescent human serum albumin (HSA800), emerged as the molecule with the best overall performance with respect to entry to lymphatics, flow to the SLN, retention in the SLN, fluorescence yield and reproducibility. This preclinical study, performed on large animals approaching the size of humans, should serve as a foundation for future clinical studies. Mol Imaging (2005) 4, 172 – 181

Anaemia, iron status and vitamin A deficiency among adolescent refugees in Kenya and Nepal

AbstractObjectiveTo investigate the prevalence of anaemia (haemoglobin 8.3 μg ml−1) and vitamin A deficiency (serum retinol < 0.7 μmoll−1) in adolescent refugees.DesignCross-sectional surveys.SettingKakuma refugee camp in Kenya and seven refugee camps in Nepal.SubjectsAdolescent refugee residents in these camps.ResultsAnaemia was present in 46% (95% confidence interval (CI): 42–51) of adolescents in Kenya and in 24% (95% CI: 20–28) of adolescents in Nepal. The sensitivity of palmar pallor in detecting anaemia was 21%. In addition, 43% (95% CI: 36–50) and 53% (95% CI: 46–61) of adolescents in Kenya and Nepal, respectively, had iron deficiency. In both surveys, anaemia occurred more commonly among adolescents with iron deficiency. Vitamin A deficiency was found in 15% (95% CI: 10–20) of adolescents in Kenya and 30% (95% CI: 24–37) of adolescents in Nepal. Night blindness was not more common in adolescents with vitamin A deficiency than in those without vitamin A deficiency. In Kenya, one of the seven adolescents with Bitot's spots had vitamin A deficiency.ConclusionsAnaemia, iron deficiency and vitamin A deficiency are common among adolescents in refugee populations. Such adolescents need to increase intakes of these nutrients; however, the lack of routine access makes programmes targeting adolescents difficult. Adolescent refugees should be considered for assessment along with other at-risk groups in displaced populations

OPA1 mutations cause cytochrome c oxidase deficiency due to loss of wild-type mtDNA molecules.

Pathogenic OPA1 mutations cause autosomal dominant optic atrophy (DOA), a condition characterized by the preferential loss of retinal ganglion cells and progressive optic nerve degeneration. Approximately 20% of affected patients will also develop more severe neuromuscular complications, an important disease subgroup known as DOA(+). Cytochrome c oxidase (COX)-negative fibres and multiple mitochondrial DNA (mtDNA) deletions have been identified in skeletal muscle biopsies from patients manifesting both the pure and syndromal variants, raising the possibility that the accumulation of somatic mtDNA defects contribute to the disease process. In this study, we investigated the mtDNA changes induced by OPA1 mutations in skeletal muscle biopsies from 15 patients with both pure DOA and DOA(+) phenotypes. We observed a 2- to 4-fold increase in mtDNA copy number at the single-fibre level, and patients with DOA(+) features had significantly greater mtDNA proliferation in their COX-negative skeletal muscle fibres compared with patients with isolated optic neuropathy. Low levels of wild-type mtDNA molecules were present in COX-deficient muscle fibres from both pure DOA and DOA(+) patients, implicating haplo-insufficiency as the mechanism responsible for the biochemical defect. Our findings are consistent with the 'maintenance of wild-type' hypothesis, the secondary mtDNA deletions induced by OPA1 mutations triggering a compensatory mitochondrial proliferative response in order to maintain an optimal level of wild-type mtDNA genomes. However, when deletion levels reach a critical level, further mitochondrial proliferation leads to replication of the mutant species at the expense of wild-type mtDNA, resulting in the loss of respiratory chain COX activity

Ecological resilience in lakes and the conjunction fallacy

There is a pressing need to apply stability and resilience theory to environmental management to restore degraded ecosystems effectively and to mitigate the effects of impending environmental change. Lakes represent excellent model case studies in this respect and have been used widely to demonstrate theories of ecological stability and resilience that are needed to underpin preventative management approaches. However, we argue that this approach is not yet fully developed because the pursuit of empirical evidence to underpin such theoretically grounded management continues in the absence of an objective probability framework. This has blurred the lines between intuitive logic (based on the elementary principles of probability) and extensional logic (based on assumption and belief) in this field

Storm impacts on phytoplankton community dynamics in lakes

In many regions across the globe, extreme weather events such as storms have increased in frequency, intensity, and duration due to climate change. Ecological theory predicts that such extreme events should have large impacts on ecosystem structure and function. High winds and precipitation associated with storms can affect lakes via short‐term runoff events from watersheds and physical mixing of the water column. In addition, lakes connected to rivers and streams will also experience flushing due to high flow rates. Although we have a well‐developed understanding of how wind and precipitation events can alter lake physical processes and some aspects of biogeochemical cycling, our mechanistic understanding of the emergent responses of phytoplankton communities is poor. Here we provide a comprehensive synthesis that identifies how storms interact with lake and watershed attributes and their antecedent conditions to generate changes in lake physical and chemical environments. Such changes can restructure phytoplankton communities and their dynamics, as well as result in altered ecological function (e.g., carbon, nutrient and energy cycling) in the short‐ and long‐term. We summarize the current understanding of storm‐induced phytoplankton dynamics, identify knowledge gaps with a systematic review of the literature, and suggest future research directions across a gradient of lake types and environmental conditions