Spatiotemporal studies of black spruce forest soils and implications for the fate of C

Post-fire storage of carbon (C) in organic-soil horizons was measured in one Canadian and three Alaskan chronosequences in black spruce forests, together spanning stand ages of nearly 200 yrs. We used a simple mass balance model to derive estimates of inputs, losses, and accumulation rates of C on timescales of years to centuries. The model performed well for the surface and total organic soil layers and presented questions for resolving the dynamics of deeper organic soils. C accumulation in all study areas is on the order of 20–40 gC/m2/yr for stand ages up to ∼200 yrs. Much larger fluxes, both positive and negative, are detected using incremental changes in soil C stocks and by other studies using eddy covariance methods for CO2. This difference suggests that over the course of stand replacement, about 80% of all net primary production (NPP) is returned to the atmosphere within a fire cycle, while about 20% of NPP enters the organic soil layers and becomes available for stabilization or loss via decomposition, leaching, or combustion. Shifts toward more frequent and more severe burning and degradation of deep organic horizons would likely result in an acceleration of the carbon cycle, with greater CO2 emissions from these systems overall

The reniform reflecting superposition compound eyes of Nephrops norvegicus: optics, susceptibility to light-induced damage, electrophysiology and a ray tracing model

The large reniform eyes of the reptant, tube-dwelling decapod Nephrops norvegicus are described in detail. Optically these reflecting superposition compound eyes are a little unusual in that they are laterally flattened, a feature that may enhance their sensitivity in that region, albeit at the expense of resolution. Electrophysiological and anatomical investigations suggest that the eyes are tuned to appropriate spectral and temporal sensitivities in the long and short term through movement of proximal pigments and possibly rhabdom adaptation. Although exposure to ambient surface light intensities is shown to cause damage to the retinal layer, especially in deeper living animals, there is no evidence yet that demonstrates an impact of eye damage on their survival. It is suggested that experimentation on marine decapods, with sensitive eyes, requires that particular attention is paid to their light environment

Encouraging a better practicum/internship experience by developing and implementing learning modules

The use of developmentally-based series of learning modules in practicum and internship courses will be discussed. These modules are designed to reinforce key knowledge and skills acquired in the program; allowing courses to incorporate their core and specialty area objectives more systematically into their clinical experiences and evaluate their program

An Effective Chemical Deterrent for Invasive Cuban Treefrogs

Introduced vertebrates have a variety of impacts on ecosystems and economies, and many cause problems for humans. One such problem is the loss of electrical power when invasive animals cause short circuits in power-transmission equipment. Cuban treefrogs (Osteopilus septentrionalis) are known to cause power outages and are a nuisance to humans when they invade homes and defecate on doors and windows. These large, slightly toxic treefrogs were introduced into Florida from the Caribbean. They now occur throughout the peninsula of Florida and are spreading to other states in the Southeast. We used refuge choice experiments to test the effectiveness of Sniff ’n’ StopTM animal deterrent to exclude Cuban treefrogs from enclosed spaces, such as utility switchgear boxes. We found that the deterrent was effective and showed potential as a low-cost means to prevent frog-related power outages and reduce conflicts with residents in the urbanized areas preferred by these invasive frog

Inconsistent Divergence of Mitochondrial-DNA in the Spontaneously Hypertensive Rat

We have recently shown that the spontaneously hypertensive rat (SHR) and the Wistar-Kyoto (WKY) rat differ at a frequency of 1 per 62 bases in their nuclear DNA (Hypertension 1992;19:425-427). Given the origin of these strains this level of divergence was unexpected. To investigate the origin of this nuclear divergence we have examined mitochondrial DNA. Mitochondrial DNA was isolated from SHR and WKY rats, digested with several restriction enzymes, electrophoresed in 1.0% agarose gels, and the fragments visualized with ethidium bromide staining. This approach allowed us to analyze 220 base pairs of mitochondrial DNA. No differences were detected between SHR and WKY rats. Comparison with the King-Holtzman rat strain produced differences at an average of 1 per 52 base pairs. We also examined several SHR and WKY rats from within our colonies and found no differences suggesting intrastrain homogeneity for mitochondrial DNA phenotypes. These data indicate that the SHR and WKY rat share a recent, common maternal ancestor. This result is consistent with the published origins of the SHR and WKY rat strains. Together with the nuclear divergence results, the data suggest that the original Wistar colony from which SHR and WKY rats were derived was probably highly polymorphic for nuclear genes

Effect of Meter Orientation Downstream of a Short Radius Elbow on Electromagnetic Flow Meters

Electromagnetic flow meters (known as magnetic flow meters) are a widely used type of flow meter. This study examines the performance of magnetic flow meters when the electrodes in the meter are positioned at two different orientations: electrodes parallel with the plane of an upstream 90° short radius elbow and electrodes perpendicular to the plane of an upstream 90° short radius elbow. Four different meters from four different manufacturers were included in the study in which a baseline straight pipe test was first performed using more than 50 diameters of straight pipe upstream of each meter. The four meters were then installed at five different locations downstream from a 90° short-radius elbow. At each location, the meters were tested in two orientations at five different flow rates. From this study, shifts in the flow rate were observed with the electrodes located at two different orientations. These shifts in flow rate ranged from 0.01% to 4.40% of the total flow measurement, and the average shifts in flow rate ranged from 0.07% to 2.78%. For the purposes of this study, the shift in flow rate is the percentage relative to the baseline test. The results from this study illustrated that there is a significant difference in measurement accuracy when the meter electrodes are installed at different orientations relative to the plane of the bend

Interactive Visual Histories for Vector Graphics

Presentation and graphics software enables users to experiment with variations of illustrations. They can revisit recent editing operations using the ubiquitous undo command, but they are limited to sequential exploration. We propose a new interaction metaphor and visualization for operation history. While editing, a user can access a history mode in which actions are denoted by graphical depictions appearing on top of the document. Our work is inspired by the visual language of film storyboards and assembly instructions. Our storyboard provides an interactive visual history, summarizing the editing of a document or a selected object. Each view is composed of action depictions representing the userâ s editing actions and enables the user to consider the operation history in context rather than in a disconnected list view. This metaphor provides instant access to any past action and we demonstrate that this is an intuitive interface to a selective undo mechanism

A sweeter way of teaching health and safety

The underpinning educational theory for practical work is that of experimental learning or 'learning by and through doing'. Hands-on practical work promotes learning as it provides students with an opportunity to put theory into practice. There are many hazards with practical work, each with an associated risk that students will encounter while they are working in the laboratory and, therefore, adequate instruction should be given before students carry out any practical work. Getting students to engage with this in the past has been difficult due to the dryness of the material. Here we show how every students sweet tooth can be used to teach them risk assessment, experimental design and embedding health and safety as part of their scientific culture

Montana Flume Flow Corrections Under Submerged Flow

A Montana flume is a Parshall flume without a diverging downstream section and is used to measure open channel flow. Under free-flow conditions, the Parshall flume and the Montana flume have the same calibration characteristics, but under submerge flows, their calibrations significantly differ. Tests were conducted at the Utah Water Research Laboratory on an acrylic 15.2-cm (6-in.) Montana flume to determine the effects of submergence on the flow readings. This type of investigation has not been previously analyzed. It was found that a standard Parshall flume rating curve overpredicted flow rates in the submerged Montana flume, up to 48%. Parshall submergence corrections were applied to the submerged Montana flume, and flow rates were underpredicted by up to 19%. This study has developed submerged flow rate correction factors specifically for a Montana flume, and the paper also demonstrates how to apply the corrections