Search results for "Magnification"

Bioaccumulation, Biodistribution, Toxicology and Biomonitoring of Organofluorine Compounds in Aquatic Organisms

2021

This review is a survey of recent advances in studies concerning the impact of poly- and perfluorinated organic compounds in aquatic organisms. After a brief introduction on poly- and perfluorinated compounds (PFCs) features, an overview of recent monitoring studies is reported illustrating ranges of recorded concentrations in water, sediments, and species. Besides presenting general concepts defining bioaccumulative potential and its indicators, the biodistribution of PFCs is described taking in consideration different tissues/organs of the investigated species as well as differences between studies in the wild or under controlled laboratory conditions. The potential use of species as bioi…

Local structure of self-affine sets

2011

The structure of a self-similar set with open set condition does not change under magnification. For self-affine sets the situation is completely different. We consider planar self-affine Cantor sets E of the type studied by Bedford, McMullen, Gatzouras and Lalley, for which the projection onto the horizontal axis is an interval. We show that within small square neighborhoods of almost each point x in E, with respect to many product measures on address space, E is well approximated by product sets of an interval and a Cantor set. Even though E is totally disconnected, the limit sets have the product structure with interval fibres, reminiscent to the view of attractors of chaotic differentia…

The trophic transfer of persistent pollutants (HCB, DDTs, PCBs) within polar marine food webs.

2017

Biomagnification (increase in contaminant concentrations at successively higher levels of trophic web), is a process that can transversally impair biodiversity and human health. Most research shows that biomagnification should be higher at poles with northern sites having a major tendency to biomagnify Persistent Organic Pollutants (POPs) through their marine food webs. We investigated the biomagnification degree into two marine trophic webs combining carbon and nitrogen stable isotopes and POP analyses. We showed that the Antarctic trophic web was more depleted than the sub-Arctic one and the differences highlighted for the basal part could explain the difference in length between them. Co…

Horizontal and vertical food web structure drives trace element trophic transfer in Terra Nova Bay, Antarctica

2019

Abstract Despite a vast amount of literature has focused on trace element (TE) contamination in Antarctica during the last decades, the assessment of the main pathways driving TE transfer to the biota is still an overlooked issue. This limits the ability to predict how variations in sea-ice dynamics and productivity due to climate change will affect TE allocation in the food web. Here, food web structure of Tethys Bay (Terra Nova Bay, Ross Sea, Antarctica) was first characterised by analysing carbon and nitrogen stable isotopes (δ13C, δ15N) in organic matter sources (sediment and planktonic, benthic and sympagic primary producers) and consumers (zooplankton, benthic invertebrates, fish and …

HCB, p,p'-DDE and PCB ontogenetic transfer and magnification in bluefin tuna (Thunnus thynnus) from the Mediterranean Sea.

2007

The bluefin tuna, Thunnus thynnus (Linnaeus 1758), is biologically and economically important in the Atlantic--Mediterranean ecosystems. Bluefin tuna feed on diverse food items depending on their age, thus they occupy different trophic levels during their lifespan. Hexachlorobenzene (HCB), p,p'-DDE and polychlorinated biphenyls (PCBs) are well-known persistent organic pollutants (POPs) in the Mediterranean basin. The relationship between stable isotopes of nitrogen (N) and the POP residue levels in tissues has recently increased knowledge on the link between the trophic levels and the contaminant accumulation. Trophic levels were estimated by using 15N/14N ratio (delta15N) and HCB, p,p'-DDE…

Trace metal transfer in the food webs of a semi-enclosed coastal ecosystem (Stagnone di Marsala, Sicily, Italy)

2010

Super-resolution-based magnification of endothelium cells from biomicroscope videos of the cornea

2018

We present a practical, robust, and effective pipeline to compute a high-resolution (HR) image of the corneal endothelium starting from a low-resolution (LR) video sequence obtained with a general purpose slit lamp biomicroscope. An image quality typical of dedicated and more expensive confocal microscopes is achieved via software magnification by exploiting information redundancy in the video sequence. In particular, the HR image is generated from the best LR frames, obtained by identifying the most suitable endothelium video subsequence using a support vector machine-based learning approach, followed by a robust graph-based frame registration. Results on long, real sequences show that the…

Red Cell Interactions with the Microcirculation

1976

We have measured RBC velocity profiles for mammalian arterioles and venules from high-speed cinematographic motion pictures. Measurements were made at 320× and 400× optical magnification over an averaging time period of 10 ms. In vivo profiles are uniformly nonsymmetrical, the RBCs exhibit rotation, and they frequently deviate sidewise from the overall axial direction of motion. In general, this is more pronounced on the venous side. Since all of the profiles are time variant and the average values are synchronous with the midstream velocity, individual RBC velocities will vary about the average. Profiles become more blunted in vessels with smaller diameters. In vessels below 16 μm diameter…

Radon–Wigner display: a compact optical implementation with a single varifocal lens

2008

A new optical implementation of the Radon‐Wigner display for one-dimensional objects is presented, making use of the fractional Fourier transform approach. The proposed setup makes use of only two conventional refractive elements: a cylindrical lens and a varifocal lens. Although the exact magnifications cannot be achieved simultaneously for all the fractional transforms, an optimum design can be obtained through balancing the conflicting magnification requirements. Experimental results are obtained with a commercially available progressive addition lens. For comparison, computer simulations are also provided. © 1997 Optical Society of America

Ultrasound Effects after Post Space Preparation: An SEM Study

2006

The aim of this study was to evaluate the effect of ultrasonic treatment on occlusion of dentine tubules in root canal walls after post space preparation in endodontically treated teeth. Twenty-four premolars were instrumented and filled using warm vertical condensation; after post space preparation, they were divided into two groups. The control group was treated using the etching procedure. The experiment samples were treated with EDTA irrigation and ultrasound activation for 30 s before the etching procedure. The roots were divided and the canal walls were examined under SEM at 1000x magnification. The debris and open tubule marks were observed at 2, 6, and 10 mm levels using a three-ste…