Abundance and exploitation rate of the blue crab (Callinectes sapidus) in Chesapeake Bay

We estimated absolute abundance of the blue crab stock in Chesapeake Bay during winter from stratified random surveys conducted baywide from 1990 to 1999, using the swept-area method. We estimated catching efficiency of the survey gear from multiple depletion experiments to correct for temporal and vessel/area differences in catchability. The survey was conducted during the winter, when crabs are dormant and buried in the bottom. Analysis of crab carapace width (CW) frequency distributions revealed two size modes: CW less or equal 60 mm and CW greater than 60 mm, corresponding to age-0 (recruits) and age-1+ (one year and older), respectively. Absolute density of blue crab recruits varied from 10 to 55 crabs per 1,000 m(2) across years (95 million to 540 million baywide), with no significant trends over time. Abundance of age-1 + crabs declined significantly from 35 to 38 crabs per I 000 m(2) in 1990-1991 (342 million to 371 million crabs baywide) to 8.3 in 1999 (92 million crabs baywide). A stronger decline in the number of males indicates that males were exploited more intensively than females. A three-year moving average of spawning stock abundance (age- 1+ females) declined twofold from the early to the late 1990s. The absolute abundance of the blue crab population in Chesapeake Bay varied from 241 million to 867 million. Over-wintering mortality was usually less than 2%, but substantially higher mortality occurred in 1994 (7.3%) and 1996 (11.9%). High correlation between January water temperature and the percentage of dead crabs provides strong evidence of the adverse effect of cold winter on survival of crabs. Large crabs were affected most by cold winter temperatures. We estimated exploitation rates for the commercial fishery by comparing abundance with total landings. The estimated exploitation rates varied from 40% to 52% from 1990 to 1998 and increased to a record high of 70% in 1999. Fishing mortality rates varied from 0.6 to 0.9 year(-1) ill most years and were above the level providing maximum yield per recruit (F-max = 0.64 year(-1)) in nearly all years. The record fishing mortality in 1999 (F-1999, = 1.6 year(-1)) exceeded the overfishing threshold (F-10% = 1.0 year(-1)). Despite evidence of growth overfishing, the blue crab population supported large harvests throughout the 1990s. Increase of fishing mortality above the F-10% in 1999, indicates that the population was overfished and is at risk of recruitment overfishing if fishing mortality remains at this level

Implications of large scale shifts in tropospheric NOx levels in the remote tropical Pacific

A major observation recorded during NASA's western Pacific Exploratory Mission (PEM-West B) was the large shift in tropical NO levels as a function of geographical location. High-altitude NO levels exceeding 100 pptv were observed during portions of tropical flights 5-8, while values almost never exceeded 20 pptv during tropical flights 9 and 10. The geographical regions encompassing these two flight groupings are here labeled "high" and "low" NOx regimes. A comparison of these two regimes, based on back trajectories and chemical tracers, suggests that air parcels in both were strongly influenced by deep convection. The low NOx regime appears to have been predominantly impacted by marine convection, whereas the high NOx regime shows evidence of having been more influenced by deep convection over a continental land mass. DMSP satellite observations point strongly toward lightning as the major source of NOx in the latter regime. Photochemical ozone formation in the high NOx regime exceeded that for low NOx by factors of 2 to 6, whereas O3 destruction in the low NOx regime exceeded that for high NOx by factors of up to 3. Taking the tropopause height to be 17 km, estimates of the net photochemical effect on the O3 column revealed that the high NOx regime led to a small net production. By contrast, the low NOx regime was shown to destroy O3 at the rate of 3.4% per day. One proposed mechanism for off-setting this projected large deficit would involve the transport of O3 rich midlatitude air into the tropics. Alternatively, it is suggested that O3 within the tropics may be overall near self-sustaining with respect to photochemical activity. This scenario would require that some tropical regions, unsampled at the time of PEM-B, display significant net column O3 production, leading to an overall balanced budget for the "greater" tropical Pacific basin. Details concerning the chemical nature of such regimes are discussed

A pilot study of the King LT supralaryngeal airway use in a rural Iowa EMS system

Introduction In 2003, the King Laryngeal Tube (LT) received FDA approval for US sales. Prehospital systems in urban setting have begun evaluating and adopting the LT for clinical airway management. However, it is not routinely approved by State EMS Boards for use by all prehospita

OH and HO2 chemistry in the North Atlantic free troposphere

Interactions between atmospheric hydrogen oxides and aircraft nitrogen oxides determine the impact of aircraft exhaust on atmospheric chemistry. To study these interactions, the Subsonic Assessment: Ozone and Nitrogen Oxide Experiment (SONEX) assembled the most complete measurement complement to date for studying HO(x) (OH and HO2) chemistry in the free troposphere. Observed and modeled HO(x) agree on average to within experimental uncertainties (±40%). However, significant discrepancies occur as a function of NO and at solar zenith angles >70°. Some discrepancies appear to be removed by model adjustments to HO(x)-NO(x) chemistry, particularly by reducing HO2NO2 (PNA) and by including heterogeneous reactions on aerosols and cirrus clouds

Seasonal differences in the photochemistry of the South Pacific: A comparison of observations and model results from PEM-Tropics A and B

A time-dependent photochemical box model is used to examine the photochemistry of the equatorial and southern subtropical Pacific troposphere with aircraft data obtained during two distinct seasons: the Pacific Exploratory Mission-Tropics A (PEM-Tropics A) field campaign in September and October of 1996 and the Pacific Exploratory Mission-Tropics B (PEM-Tropics B) campaign in March and April of 1999. Model-predicted values were compared to observations for selected species (e.g., NO2, OH, HO2) with generally good agreement. Predicted values of HO2 were larger than those observed in the upper troposphere, in contrast to previous studies which show a general underprediction of HO2 at upper altitudes. Some characteristics of the budgets of HOx, NOx, and peroxides are discussed. The integrated net tendency for O3 is negative over the remote Pacific during both seasons, with gross formation equal to no more than half of the gross destruction. This suggests that a continual supply of O3 into the Pacific region throughout the year must exist in order to maintain O3 levels. Integrated net tendencies for equatorial O3 showed a seasonality, with a net loss of 1.06×1011 molecules cm-2 s-1 during PEM-Tropics B (March) increasing by 50% to 1.60×1011 molecules cm-2 s-1 during PEM-Tropics A (September). The seasonality over the southern subtropical Pacific was somewhat lower, with losses of 1.21×1011 molecules cm-2 s-1 during PEM-Tropics B (March) increasing by 25% to 1.51×1011 molecules cm-2 s-1 during PEM-Tropics A (September). While the larger net losses during PEM-Tropics A were primarily driven by higher concentrations of O3, the ability of the subtropical atmosphere to destroy O3 was ∼30% less effective during the PEM-Tropics A (September) campaign due to a drier atmosphere and higher overhead O3 column amounts. Copyright 2001 by the American Geophysical Union

Smaller Hippocampal Volume in Posttraumatic Stress Disorder: A Multisite ENIGMA-PGC Study: Subcortical Volumetry Results From Posttraumatic Stress Disorder Consortia

BACKGROUND—Many studies report smaller hippocampal and amygdala volumes in posttraumatic stress disorder (PTSD), but findings have not always been consistent. Here, we present the results of a large-scale neuroimaging consortium study on PTSD conducted by the Psychiatric Genomics Consortium (PGC)–Enhancing Neuroimaging Genetics through Meta-Analysis (ENIGMA) PTSD Working Group. METHODS—We analyzed neuroimaging and clinical data from 1868 subjects (794 PTSD patients) contributed by 16 cohorts, representing the largest neuroimaging study of PTSD to date. We assessed the volumes of eight subcortical structures (nucleus accumbens, amygdala, caudate, hippocampus, pallidum, putamen, thalamus, and lateral ventricle). We used a standardized image-analysis and quality-control pipeline established by the ENIGMA consortium. RESULTS—In a meta-analysis of all samples, we found significantly smaller hippocampi in subjects with current PTSD compared with trauma-exposed control subjects (Cohen’s d = −0.17, p = .00054), and smaller amygdalae (d = −0.11, p = .025), although the amygdala finding did not survive a significance level that was Bonferroni corrected for multiple subcortical region comparisons (p \u3c .0063). CONCLUSIONS—Our study is not subject to the biases of meta-analyses of published data, and it represents an important milestone in an ongoing collaborative effort to examine the neurobiological underpinnings of PTSD and the brain’s response to trauma

ciliaFA : a research tool for automated, high-throughput measurement of ciliary beat frequency using freely available software

Background: Analysis of ciliary function for assessment of patients suspected of primary ciliary dyskinesia (PCD) and for research studies of respiratory and ependymal cilia requires assessment of both ciliary beat pattern and beat frequency. While direct measurement of beat frequency from high-speed video recordings is the most accurate and reproducible technique it is extremely time consuming. The aim of this study was to develop a freely available automated method of ciliary beat frequency analysis from digital video (AVI) files that runs on open-source software (ImageJ) coupled to Microsoft Excel, and to validate this by comparison to the direct measuring high-speed video recordings of respiratory and ependymal cilia. These models allowed comparison to cilia beating between 3 and 52 Hz. Methods: Digital video files of motile ciliated ependymal (frequency range 34 to 52 Hz) and respiratory epithelial cells (frequency 3 to 18 Hz) were captured using a high-speed digital video recorder. To cover the range above between 18 and 37 Hz the frequency of ependymal cilia were slowed by the addition of the pneumococcal toxin pneumolysin. Measurements made directly by timing a given number of individual ciliary beat cycles were compared with those obtained using the automated ciliaFA system. Results: The overall mean difference (± SD) between the ciliaFA and direct measurement high-speed digital imaging methods was −0.05 ± 1.25 Hz, the correlation coefficient was shown to be 0.991 and the Bland-Altman limits of agreement were from −1.99 to 1.49 Hz for respiratory and from −2.55 to 3.25 Hz for ependymal cilia. Conclusions: A plugin for ImageJ was developed that extracts pixel intensities and performs fast Fourier transformation (FFT) using Microsoft Excel. The ciliaFA software allowed automated, high throughput measurement of respiratory and ependymal ciliary beat frequency (range 3 to 52 Hz) and avoids operator error due to selection bias. We have included free access to the ciliaFA plugin and installation instructions in Additional file 1 accompanying this manuscript that other researchers may use

Adaptive mutation using statistics mechanism for genetic algorithms

Copyright @ 2004 Springer-Verla

CX3CR1 Polymorphisms are associated with atopy but not asthma in German children

Chemokines and their receptors are involved in many aspects of immunity. Chemokine CX3CL1, acting via its receptor CX3CR1, regulates monocyte migration and macrophage differentiation as well as T cell-dependent inflammation. Two common, nonsynonymous polymorphisms in CX3CR1 have previously been shown to alter the function of the CX3CL1/CX3CR1 pathway and were suggested to modify the risk for asthma. Using matrix-assisted laser desorption/ionization time-of-flight technology, we genotyped polymorphisms Val249Ile and Thr280Met in a cross-sectional population of German children from Munich (n = 1,159) and Dresden ( n = 1,940). For 249Ile an odds ratio of 0.77 (95% confidence interval 0.63-0.96; p = 0.017) and for 280Met an odds ratio of 0.71 ( 95% confidence interval 0.56-0.89; p = 0.004) were found with atopy in Dresden but not in Munich. Neither polymorphism was associated with asthma. Thus, amino acid changes in CX3CR1 may influence the development of atopy but not asthma in German children. Potentially, other factors such as environmental effects may modify the role of CX3CR1 polymorphisms. Copyright (c) 2007 S. Karger AG, Basel