Population dynamics of an exploited population of Orconectes virilis in Northwestern Ontario

Exploitation of northern stocks of the crayfish Orconectes virilis (Hagen) produced significant alterations in several population parameters. High fishing efforts increased per capita fecundity, young-of-year (YOY) production, and age- and sex-specific growth, and altered mortality patterns. Climatic variation, measured as arbitrarily defined weather variables, did not influence life history parameters in the exploited population. However, short-term temperature fluctuations affected YOY production and future reproductive potential in the control lake. The control population in Shallow Lake exhibited strong density dependence in regulating both mortality and growth rates of pre-recruit age classes. Behavioural dominance by maturing males (age I-to-age II) effectively controlled juvenile life history parameters , i.e., egg-to-YOY and YOY-to-age I mortality and growth. As a result a dynamic oscillatory relationship existed between annual age I-to-age II male growth and female year-class strength, which in turn correlated with cohort egg production. Exploitation of Dock Lake's population broke down this process so that year-class strength directly correlated with annual growth but cohort egg production varied independently. The amount harvested, using passive fishing gear, proportionately increased with increases in nominal effort. However interactions between sampling intensity, duration of harvest and behavioural responses resulted in a upper limit to the percent of the exploitable stock that that could be removed by this fishery. Rlteration of life history parameters contributed to population resilience and stability as fishing pressure increased

DNA/RNA Degradation Rate in Long Term Fixed Museum Specimens

In today’s research driven society, it has become commonplace for institutions to rely upon DNA and RNA extraction techniques to help obtain genomic data from old specimens. Generally, specimens were commonly preserved for future gross examination and/or teaching. Using histological examination of specimens from museum jars from the Pathology Department at the Indiana University School of Medicine, the sequential and chronological degradation of DNA and RNA has been studied. We examined gross specimens from nine decades from 1920 until 2000. We evaluated histologic preservation of kidney, liver, heart, lung, spleen, uterus, and brain for nuclear structure in these samples. Nuclear preservation was based on amount of nuclei per 20x microscopic field and the crispness of the nuclear membrane and internal features. The nuclei in high lipid tissues such as the brain were found to degrade at a quicker rate than dense tissues such as the heart and uterus. Our study has shown specimens preserved beyond fifty years were likely to have little to no nuclei left, thus indicating that there was little to no DNA and RNA remaining. This technique of histologic evaluation first is an important finding and a general guideline which may save research institutions from the expensive process of DNA and RNA extraction

Use of Aperio Whole Slide Imaging System to Capture and Utilize Digital Virtual Slides for Pathology Education

poster abstractDigital whole slide imaging is the technique of digitizing an entire microscope slide at the highest resolution to produce a “digital virtual microscope slide” with high image quality. This digital image can be viewed in three to four fields, from low to high power, a feature commonly used by pathologists. This digital virtual slide can be used in conjunction with image processing software (both windows-based and browser-based) to view, manipulate, position, and specify the magnification of the image on a screen as if using a regular microscope to view the original glass slide. As the slide is captured in a virtual format, it is possible to use the image for archiving, copying, transferring over networks, distant consultation, as well as integration for educational use on the web and/or DVD. In this study, we captured all C603 and C604 sophomore pathology teaching slides in the general and systemic pathology course for viewing and learning through the Aperio ImageScope viewer. The resulting digital images possessed greater ease of use, were quicker to scan and allowed easier location of pathologic lesions in the slides. The ImageScope viewer allowed students to quickly zoom in and out of the slides at multiple fields of magnification. Instructors that have switched to the Aperio system from the old Bliss system found the Aperio system allowed the instructor to open up to 8 slides at one time, allowing side by side comparison to be completed on the same screen. The system also allows one to measure the size of the cells and to capture detailed images of tumor cells, inflammatory cells, and/or necrosis (cell death). This system is available for use on desktop, laptop, and most digital devices (such as smart phones or tablets). Compared to the old Bliss system, which is unable to perform these functions

Prompt and accurate diagnosis of ventricular arrhythmias with a novel index based on phase space reconstruction of ECG

Aim: to develop a statistical index based on the phase space reconstruction (PSR) of the electrocardiogram (ECG) for the accurate and timely diagnosis of ventricular tachycardia (VT) and ventricular fibrillation (VF).Methods: thirty-two ECGs with sinus rhythm (SR) and 32 ECGs with VT/VF were analyzed using the PSR technique. Firstly, the method of time delay embedding were employed with the insertion of delay “?” in the original time-series X(t), which produces the Y(t) = X(t ? ?). Afterwards, a PSR diagram was reconstructed by plotting Y(t) against X(t). The method of box counting was applied to analyze the behavior of the PSR trajectories. Measures as mean (?), standard deviation (?) and coefficient of variation (CV = ?/?), kurtosis (?) for the box counting of PSR diagrams were reported.Results: during SR, CV was always < 0.05, while with the onset of arrhythmia CV increased > 0.05. A similar pattern was observed with ? , where < 6 was considered as the cut-off point between SR and VT/VF. Therefore, the upper threshold for SR was considered CV th = 0.05 and ?th < 6. For optimisation of the accuracy, a new index (J ) was proposed: View the MathML sourceJ=wCVCVth+1?w??th.During SR the upper limit of J was the value of 1. Furthermore CV, ? and J crossed the cut-off point timely before the onset of arrhythmia (average time: 4 min 31 s; SD: 2 min 30 s); allowing sufficient time for preventive therapy.Conclusion: the J index improved ECG utility for arrhythmia monitoring and detection utility, allowing the prompt and accurate diagnosis of ventricular arrhythmias

Remarks on the f_0(400-1200) scalar meson as the dynamically generated chiral partner of the pion

The quark-level linear sigma model is revisited, in particular concerning the identification of the f_0(400-1200) (or \sigma(600)) scalar meson as the chiral partner of the pion. We demonstrate the predictive power of the linear sigma model through the pi-pi and pi-N s-wave scattering lengths, as well as several electromagnetic, weak, and strong decays of pseudoscalar and vector mesons. The ease with which the data for these observables are reproduced in the linear sigma model lends credit to the necessity to include the sigma as a fundamental q\bar{q} degree of freedom, to be contrasted with approaches like chiral perturbation theory or the confining NJL model of Shakin and Wang.Comment: 15 pages, plain LaTeX, 3 EPS figure

Insight Into the Molecular Mechanisms for Microcystin Biodegradation in Lake Erie and Lake Taihu

Microcystins are potent hepatotoxins that are frequently detected in fresh water lakes plagued by toxic cyanobacteria. Microbial biodegradation has been referred to as the most important avenue for removal of microcystin from aquatic environments. The biochemical pathway most commonly associated with the degradation of microcystin is encoded by the mlrABCD (mlr) cassette. The ecological significance of this pathway remains unclear as no studies have examined the expression of these genes in natural environments. Six metatranscriptomes were generated from microcystin-producing Microcystis blooms and analyzed to assess the activity of this pathway in environmental samples. Seventy-eight samples were collected from Lake Erie, United States/Canada and Lake Tai (Taihu), China, and screened for the presence of mlr gene transcripts. Read mapping to the mlrcassette indicated transcripts for these genes were absent, with only 77 of the collective 3.7 billion reads mapping to any part of the mlr cassette. Analysis of the assembled metatranscriptomes supported this, with only distantly related sequences identified as mlrABC-like. These observations were made despite the presence of microcystin and over 500,000 reads mapping to the mcy cassette for microcystin production. Glutathione S-transferases and alkaline proteases have been previously hypothesized to be alternative pathways for microcystin biodegradation, and expression of these genes was detected across space and time in both lakes. While the activity of these alternative pathways needs to be experimentally confirmed, they may be individually or collectively more important than mlr genes in the natural environment. Importantly, the lack of mlr expression could indicate microcystin biodegradation was not occurring in the analyzed samples. This study raises interesting questions about the ubiquity, specificity and locality of microcystin biodegradation, and highlights the need for the characterization of relevant mechanisms in natural communities to understand the fate of microcystin in the environment and risk to public health

DNA/RNA Degradation Rate in Fixed Tissue

poster abstractIn today’s research driven society, it has become commonplace for institutions to rely upon DNA and RNA extraction techniques to help obtain genomic data from old specimens. Generally, specimens were commonly preserved for future gross examination and/or teaching. Using histological examination of specimens from museum jars from the Pathology Department at the Indiana University School of Medicine, the sequential and chronological degradation of DNA and RNA has been studied. We examined gross specimens from nine decades from 1920 until 2000. We evaluated histologic preservation of nuclear structure in these samples. Nuclear preservation was based on amount of nuclei per 20x microscopic field, the crispness of the nuclear membrane and internal features. The nuclei in high lipid tissues such as the brain were found to degrade at a quicker rate than dense proteinaceous structures such as the heart and uterus. Our study has shown specimens preserved beyond roughly fifty years are likely to have little to no nuclei left, thus indicating that there was little to no DNA and RNA remaining. This technique of histologic evaluation is an important finding and general guideline which may save research institutions from the expensive process of DNA and RNA extractio

Practical quantum cryptography for secure free-space communications

Quantum cryptography is an emerging technology in which two parties may simultaneously generate shared, secret cryptographic key material using the transmission of quantum states of light. The security of these transmissions is based on the inviolability of the laws of quantum mechanics and information-theoretically secure post-processing methods. An adversary can neither successfully tap the quantum transmissions, nor evade detection, owing to Heisenberg's uncertainty principle. In this paper we describe the theory of quantum cryptography, and the most recent results from our experimental free-space system with which we have demonstrated for the first time the feasibility of quantum key generation over a point-to-point outdoor atmospheric path in daylight. We achieved a transmission distance of 0.5 km, which was limited only by the length of the test range. Our results provide strong evidence that cryptographic key material could be generated on demand between a ground station and a satellite (or between two satellites), allowing a satellite to be securely re-keyed on orbit. We present a feasibility analysis of surface-to-satellite quantum key generation.Comment: 12 pages, 4 figure