Status of the Major Oyster Diseases in Virginia 2004 A Summary of the Annual Monitoring Program

2004 was the second very wet year in a row. While rainfall and streamflows were normal in winter and early spring, and just slightly above average during the summer, the fall of 2004 was nearly as wet as the year before. Salinities were again depressed throughout the lower Bay. Water temperatures were below normal during the winter, but typical otherwise. Low salinities and, in the winter, temperatures brought continued abatement in the oyster diseases caused by Perkinsus marinus (Dermo) and Haplosporidium nelsoni (MSX). Among quarterly James River Survey sites, maximum annual P. marinus prevalences were the lowest they had been since before 1992. In summer and fall, when P. marinus is normally most prevalent, it was found in a maximum of 68% of oysters at Wreck Shoal and in no more than 20% of the oysters anywhere else. Advanced infections were rare, and limited to Wreck Shoal. H. nelsoni was found in a single oyster, at Wreck Shoal in July

Status of the Major Oyster Diseases in Virginia 2005 A Summary of the Annual Monitoring Program

More normal riverflows and salinities returned in 2005 after two very wet years. Temperatures were somewhat colder than normal during the winter, and warmer during the summer. The physical environment was generally more favorable for parasite activity, and thus brought a slight increase in prevalence and intensity of the oyster diseases caused by Perkinsus marinus (Dermo) and Haplosporidium nelsoni (MSX). Among quarterly James River Survey sites, maximum annual P. marinus prevalences returned to levels typical of the mid- 1990s, before the years of drought. P. marinus prevalence reached 92% at Wreck Shoal, 56% at Point of Shoal, 68% at Horsehead Rock, and 8% at Deepwater Shoal, where P. marinus was observed for the first time since early 2003. More advanced, heavy infections became more numerous, but were limited to Wreck Shoal. H. nelsoni was restricted to Wreck Shoal, where it increased in maximum prevalence from 4% to 20%

Status of the Major Oyster Diseases in Virginia 2006-2008 A Summary of the Annual Oyster Disease Monitoring Program

Fall Survey sampling revealed P. marinus levels to be generally normal to high in Virginia tributaries. By 2007 P. marinus was present on every oyster reef sampled, and by the end of the 2006-2008 period the parasite was probably causing some mortality throughout Virginia waters. Data for H. nelsoni are still incomplete for 2006/7 because of funding limitations, but in 2008 H. nelsoni was observed at 17 of 31 sampled reefs, a marked expansion in distribution since 2003/4. A significant MSX disease outbreak occurred in the Great Wicomico River in 2008, as a mild winter and a long period of elevated salinities supported increased H. nelsoni activity among a population of relatively susceptible oysters. Analyses of Spring Imports deployments of susceptible upper Rappahannock River oysters to the York River revealed typically high annual levels of disease-related oyster mortality, each year exceeding 88%. Perkinsus marinus began to affect the deployment relatively early in 2006 and 2008, with prevalences around 50% and moderate infections emerging by early July. Infections developed more slowly in 2007, but by August of each year P. marinus levels were similar: 96% prevalence, with abundant moderate and some heavy infections. Late summer and fall P. marinus levels were above the long-term average for Spring Imports deployments. Peak H. nelsoni impacts on the Spring Imports deployments during 2006-2008 were typical, but the onset of serious MSX disease occurred earlier than normal in 2006, with prevalence reaching 88% and intense infections abundant by early July. Early July H. nelsoni levels were lower than normal in 2007 and 2008

Heterodyne range imaging as an alternative to photogrammetry

Solid-state full-field range imaging technology, capable of determining the distance to objects in a scene simultaneously for every pixel in an image, has recently achieved sub-millimeter distance measurement precision. With this level of precision, it is becoming practical to use this technology for high precision three-dimensional metrology applications. Compared to photogrammetry, range imaging has the advantages of requiring only one viewing angle, a relatively short measurement time, and simplistic fast data processing. In this paper we fist review the range imaging technology, then describe an experiment comparing both photogrammetric and range imaging measurements of a calibration block with attached retro-reflective targets. The results show that the range imaging approach exhibits errors of approximately 0.5 mm in-plane and almost 5 mm out-of-plane; however, these errors appear to be mostly systematic. We then proceed to examine the physical nature and characteristics of the image ranging technology and discuss the possible causes of these systematic errors. Also discussed is the potential for further system characterization and calibration to compensate for the range determination and other errors, which could possibly lead to three-dimensional measurement precision approaching that of photogrammetry

The Waikato range imager

We are developing a high precision simultaneous full-field acquisition range imager. This device measures range with sub millimetre precision in range simultaneously over a full-field view of the scene. Laser diodes are used to illuminate the scene with amplitude modulation with a frequency of 10MHz up to 100 MHz. The received light is interrupted by a high speed shutter operating in a heterodyne configuration thus producing a low-frequency signal which is sampled with a digital camera. By detecting the phase of the signal at each pixel the range to the scene is determined. We show 3D reconstructions of some viewed objects to demonstrate the capabilities of the ranger

Status of the Major Oyster Diseases in Virginia 2003 A Summary of the Annual Monitoring Program

Low temperatures and salinities brought abatement in the oyster diseases caused by Perkinsus marinus (Dermo) and Haplosporidium nelsoni (MSX) for the first time since 1998. In the James River, P. marinus prevalences were the lowest they had been since 1998. In summer and fall, when P. marinus is normally most prevalent, it was found in a maximum of 72% of oysters at Wreck Shoal and in less than half the oysters at Horsehead Rock and Point of Shoals. Advanced infections were very rare. Haplosporidium nelsoni had disappeared completely from quarterly James River samples by Jul

Video-rate or high-precision: A flexible range imaging camera

A range imaging camera produces an output similar to a digital photograph, but every pixel in the image contains distance information as well as intensity. This is useful for measuring the shape, size and location of objects in a scene, hence is well suited to certain machine vision applications. Previously we demonstrated a heterodyne range imaging system operating in a relatively high resolution (512-by-512) pixels and high precision (0.4 mm best case) configuration, but with a slow measurement rate (one every 10 s). Although this high precision range imaging is useful for some applications, the low acquisition speed is limiting in many situations. The system’s frame rate and length of acquisition is fully configurable in software, which means the measurement rate can be increased by compromising precision and image resolution. In this paper we demonstrate the flexibility of our range imaging system by showing examples of high precision ranging at slow acquisition speeds and video-rate ranging with reduced ranging precision and image resolution. We also show that the heterodyne approach and the use of more than four samples per beat cycle provides better linearity than the traditional homodyne quadrature detection approach. Finally, we comment on practical issues of frame rate and beat signal frequency selection

Why are Children Still Working?

This study aims to determine the effect of household characteristics and children's living environment on child labor to reduce the likelihood of child labor occurrence. The data source of this research is Sakernas (Indonesian National Labor Force Survey) of August 2018, including school accreditation, household head gender, age, working sector, employment status, household size, dependency ratio, location, and school quality, towards the probability of child labor occurrence in Indonesia. Results suggest that the government must prioritize welfare programs for women household heads, asses the minimum age for marriage, improve education facilities, and increase parental awareness to eliminate child labor. The government needs to improve education infrastructure. This infrastructure improvement should be accompanied by the convenience of school access and its costs. The lack of education infrastructure, especialy in rural areas makes it difficult for children there to attend formal schooling

Axial-vector meson mixing in orthocharmonium decays

The new BES measurement on the two-body decays of J/psi and psi' into an axial-vector meson and a pseudoscalar meson is analyzed with the axial-K mixing including the one-photon annihilation contribution. A somewhat puzzling pattern of the K_1^+ K^- decay channels can be understood with no tight constraint on the mixing angle. The branching fractions of the K_1^0 K-bar^0 channels will be the cleanest source of information to determine the mixing angle from the 1^+ 0^- decays of J/psi and psi'.Comment: 14 pages with 4 eps figure

Mother's curse is pervasive across a large mitonuclear Drosophila panel

The maternal inheritance of mitochondrial genomes entails a sex-specific selective sieve, whereby mutations in mitochondrial DNA can only respond to selection acting on females. In theory, this enables male-harming mutations to accumulate in mitochondrial genomes as long as they are neutral, beneficial, or only slightly deleterious to females. Ultimately, this bias could drive the evolution of male-specific mitochondrial mutation loads, an idea known as mother’s curse. Earlier work on this hypothesis has mainly used small Drosophila panels, in which naturally sourced mitochondrial genomes were coupled to an isogenic nuclear background. The lack of nuclear genetic variation in these designs has precluded robust generalization. Here, we test the predictions of mother’s curse using a large Drosophila mitonuclear genetic panel, comprising nine isogenic nuclear genomes coupled to nine mitochondrial haplotypes, giving a total of 81 different mitonuclear genotypes. Following a predictive framework, we tested the mother’s curse hypothesis by screening our panel for wing size. This trait is tightly correlated with overall body size and is sexually dimorphic in Drosophila. Moreover, growth is heavily reliant on metabolism and mitochondrial function, making wing size an ideal trait for the study of the impact of mitochondrial variation. We detect high levels of mitonuclear epistasis, and more importantly, we report that mitochondrial genetic variance is larger in male than female Drosophila for eight out of the nine nuclear genetic backgrounds used. These results demonstrate that the maternal inheritance of mitochondrial DNA does indeed modulate male life history traits in a more generalisable way than previously demonstrated