Soft-bottom benthic assemblages and levels of contaminants in sediments and biota at Gray's Reef National Marine Sanctuary and nearby shelf waters off the coast of Georgia (2000 and 2001)

A series of studies was initiated to assess the condition of benthic macroinfauna and chemical contaminant levels in sediments and biota of the Gray’s Reef National Marine Sanctuary (GRNMS) and nearby shelf waters off the coast of Georgia. Four key objectives of the research are (1) to document existing environmental conditions within the sanctuary in order to provide a quantitative benchmark for tracking any future changes due to either natural or human disturbances; (2) to examine broader cross-shelf spatial patterns in benthic fauna and sediment contaminant concentrations and to identify potential controlling factors associated with the observed patterns; (3) to assess any between-year temporal variability in benthic fauna; and (4) to evaluate the importance of benthic fauna as prey for higher trophic levels. Such questions are being addressed to help fulfill long-term science and management goals of the GRNMS. However, it is anticipated that the information will be of additional value in broadening our understanding of the surrounding South Atlantic Bight (SAB) ecosystem and in bringing the knowledge to bear on related resourcemanagement issues of the region. We have begun to address the first three of these objectives with data from samples collected in spring 2000 at stations within GRNMS, and in spring 2001 at stations within the sanctuary and along three cross-shelf transects extending from the mouths of Sapelo, Doboy, and Altamaha Sounds out to sanctuary depths (about 17-20 m). This report provides a description of baseline conditions within the sanctuary, based on results of the spring 2000 survey (Section II), and uses data from both 2000 and 2001 to examine overall spatial and temporal patterns in biological and chemical variables within the sanctuary and surrounding inner-shelf environment (Section III). (PDF contains 65 pages

Plasma B-6 vitamer changes following a 50-km ultramarathon

The purpose of this study was to measure plasma B-6 vitamers, and other factors which may affect the plasma concentrations of these vitamers under extreme physical conditions. Blood samples were drawn from 8 men and 3 women (43.7 ± 8.6 years) 30 minutes prior to the start of a 50-km ultramarathon race (pre), and at 5 (PST) and 60 (PST60) minutes post race. HPLC was used to measure pyridoxal 5' phosphate (PLP), pyridoxal (PL), pyridoxine (PN), and 4-pyridoxic acid ( 4-PA). Plasma total vitamin B-6 (TB6) was measured microbiologically. Plasma glucose, albumin, and lactate concentration, and alkaline phosphatase activity, as well as hematocrit and hemoglobin levels were measured. Food and liquid intake was assessed during the run. There was a significant (p<0.0001) decrease in the plasma PLP concentration between pre and PST, with a mean decrease of 12.9 ± 8.8 nmol/L (31 % decrease). At PST60 there was a further decrease in plasma PLP concentration bringing the total decrease to 17.9 nmol/L (44%). The plasma TB6 concentration also decreased after the run, but the mean decrease was only 11 nmol/L (pre to PST60). PL increased by 25% after the run, and did not change further at PST60. The mean PN value did not change significantly after the run. The mean plasma 4-PA concentration increased by 21 % post-run and decreased to just below the pre-run value after l hour. The decrease in plasma PLP with a subsequent increase in plasma 4-PA and PL concentration's suggests that persons participating in a 50-km ultramarathon may metabolize vitamin B-6 at an increased rate, and thus have an increased requirement for vitamin B-6

Seasonal Survival and Cause-Specific Mortality of Northern Bobwhites in Mississippi

Knowledge of northern bobwhite (Colinus virginianus) survival and rates at which specific mortality agents remove individuals from the population is important for implementation of science-based harvest and habitat management regimes. To better understand population response to habitat management, we monitored 194 radio-marked northern bobwhites in managed old-field habitats in eastcentral Mississippi, 1993 to 1996. Bobwhite populations increased during the first 3 years following initiation of disking and burning practices. During the 2nd year of bobwhite habitat management breeding season survival (0.509) was high relative to other southeastern populations. However, breeding season survival declined from the 2nd through the 5th year of management (1993, 0.509; 1994, 0.362; 1995, 0.338; 1996, 0.167; P \u3c 0.001). Declining seasonal survival was attributable to increasing mammalian mortality from 1993 to 1996 (P \u3c 0.01). Avian mortality rates were stochastic and differed among years (P = 0.04), while unknown mortality rates were similar (P = 0.13). Avian mortality evidently operated in a density-dependent fashion, whereas mammalian mortality continued to increase despite declining bobwhite population. Northern bobwhite cause-specific mortality rates among years differed by sex (P \u3c 0.01) and age (P \u3c 0.01). Indices of breeding season relative abundance declined with declining survival. We hypothesize that manipulations (bum, disk, bum/disk) which created habitat that met the seasonal requirements of breeding bobwhites and other early successional prey species, may have resulted in a functional and numerical response of mammalian predators

Comparison of Two Methods for Quantifying Northern Bobwhite Habitat Use

Habitat use is an important ecological parameter that is used to make informed decisions about quail management and research. Statistical methods for quantifying habitat use are numerous, but few objective criteria are available to support the selection of a particular analytical approach. Therefore, we compared breeding season habitat use by radio-marked northern bobwhites (Colinus virginianus) at 2 study sites in Mississippi with 2 widely used statistical methods; Chi-square goodness-of-fit test with Bonferroni confidence intervals, and compositional analysis. These statistical methods produced similar results for both study areas; however, more detailed habitat use information was provided by compositional analysis when performed using the customary hierarchical approach. Therefore, for analysis of radio-marked quail, we recommend this method due to its effective hierarchical approach, improved statistical validity, and ability to incorporate other population parameters (e.g .. survival) into statistical models of habitat use by northern bobwhites

Terrestrial Myriametric Radio Burst Observed by IMAGE and Geotail Satellites

We report IMAGE and Geotail simultaneous observations of a terrestrial myriametric radio burst (TMRB) detected on August 19, 2001. The TMRB was confined in time (0830-1006 UT) and frequency (12-50 kHz), suggesting a fan beam-like emission pattern from a single discrete source. Analysis and comparisons with existing TMR radiations strongly suggest that the TMRB is a distinct emission perhaps resulting from dayside magnetic reconnection instigated by northward interplanetary field condition

High-Capacity Communications from Martian Distances

High capacity communications from Martian distances, required for the envisioned human exploration and desirable for data-intensive science missions, is challenging. NASA s Deep Space Network currently requires large antennas to close RF telemetry links operating at kilobit-per-second data rates. To accommodate higher rate communications, NASA is considering means to achieve greater effective aperture at its ground stations. This report, focusing on the return link from Mars to Earth, demonstrates that without excessive research and development expenditure, operational Mars-to-Earth RF communications systems can achieve data rates up to 1 Gbps by 2020 using technology that today is at technology readiness level (TRL) 4-5. Advanced technology to achieve the needed increase in spacecraft power and transmit aperture is feasible at an only moderate increase in spacecraft mass and technology risk. In addition, both power-efficient, near-capacity coding and modulation and greater aperture from the DSN array will be required. In accord with these results and conclusions, investment in the following technologies is recommended:(1) lightweight (1 kg/sq m density) spacecraft antenna systems; (2) a Ka-band receive ground array consisting of relatively small (10-15 m) antennas; (3) coding and modulation technology that reduces spacecraft power by at least 3 dB; and (4) efficient generation of kilowatt-level spacecraft RF power

Terrestrial Myriametric Radio Burst Observed by IMAGE and Geotail Satellites

We report the simultaneous detection of a terrestrial myriametric radio burst (TMRB) by IMAGE and Geotail on 19 August 2001. The TMRB was confined in time (0830-1006 UT) and frequency (12-50kHz). Comparisons with all known nonthermal myriametric radiation components reveal that the TMRB might be a distinct radiation with a source that is unrelated to the previously known radiation. Considerations of beaming from spin-modulation analysis and observing satellite and source locations suggest that the TMRB may have a fan beamlike radiation pattern emitted by a discrete, dayside source located along the poleward edge of magnetospheric cusp field lines. TMRB responsiveness to IMF Bz and By orientations suggests that a possible source of the TMRB could be due to dayside magnetic reconnection instigated by northward interplanetary field condition

Customer Referral Behavior: Do Switchers and Stayers Differ?

In today’s highly competitive market environment, service providers are beginning to recognize that customer referral plays an important role in enhancing firm value through cost-effective acquisition of new customers. While a significant body of research has focused on exploring customer referral, surprisingly limited research to date has addressed how customer referral may vary for different customer groups, particularly among switchers and stayers. This article examines the moderating effect of switchers and stayers on the relationships between service quality and perceived value on customer referral behavior. Actual referral data were collected from 441 customers of an Internet Service Provider in two waves for this study. The results show that the effects of positive changes in service quality and perceived value on customer referral behavior are stronger for recently acquired customers (switchers) than for long-term customers (stayers). The findings of the study suggest that investment in service quality and value improvements yield significantly higher returns (through greater customer referrals) for switchers than for stayers. Based on the findings, the authors recommend that service managers should identify and target newly acquired customers, who have switched from different service providers, right from the outset of the relationship with service offerings that signify higher quality and value in order to maximize customer referrals