After the Fall: Legacy Effects of Biogenic Structure on Wind-Generated Ecosystem Processes Following Mussel Bed Collapse

Blue mussels (Mytilus edulis) are ecosystem engineers with strong effects on species diversity and abundances. Mussel beds appear to be declining in the Gulf of Maine, apparently due to climate change and predation by the invasive green crab, Carcinus maenas. As mussels die, they create a legacy of large expanses of shell biogenic structure. In Maine, USA, we used bottom traps to examine effects of four bottom cover types (i.e., live mussels, whole shells, fragmented shells, bare sediment) and wind condition (i.e., days with high, intermediate, and low values) on flow-related ecosystem processes. Significant differences in transport of sediment, meiofauna, and macrofauna were found among cover types and days, with no significant interaction between the two factors. Wind condition had positive effects on transport. Shell hash, especially fragmented shells, had negative effects, possibly because it acted as bed armor to reduce wind-generated erosion and resuspension. Copepods had the greatest mobility and shortest turnover times (0.15 d), followed by nematodes (1.96 d) and the macrofauna dominant, Tubificoides benedeni (2.35 d). Shell legacy effects may play an important role in soft-bottom system responses to wind-generated ecosystem processes, particularly in collapsed mussel beds, with implications for recolonization, connectivity, and the creation and maintenance of spatial pattern

SigTree: A Microbial Community Analysis Tool to Identify and Visualize Significantly Responsive Branches in a Phylogenetic Tree.

Microbial community analysis experiments to assess the effect of a treatment intervention (or environmental change) on the relative abundance levels of multiple related microbial species (or operational taxonomic units) simultaneously using high throughput genomics are becoming increasingly common. Within the framework of the evolutionary phylogeny of all species considered in the experiment, this translates to a statistical need to identify the phylogenetic branches that exhibit a significant consensus response (in terms of operational taxonomic unit abundance) to the intervention. We present the R software package SigTree, a collection of flexible tools that make use of meta-analysis methods and regular expressions to identify and visualize significantly responsive branches in a phylogenetic tree, while appropriately adjusting for multiple comparisons

Administrative Law

This article is a report of certain developments during the last two years relating to the Virginia Administrative Process Act ( the VAPA ), which governs rulemaking and adjudication of cases by state agencies as well as judicial review of both

Monitoring sediment transfer processes on the desert margin

LANDSAT Thematic Mapper and Multispectral Scanner data have been used to construct change detection images for three playas in south-central Tunisia. Change detection images have been used to analyze changes in surface reflectance and absorption between wet and dry season (intra-annual change) and between different years (inter-annual change). Change detection imagery has been used to examine geomorphological changes on the playas. Changes in geomorphological phenomena are interpreted from changes in soil and foliar moisture levels, differences in reflectances between different salt and sediments and the spatial expression of geomorphological features. Intra-annual change phenomena that can be detected from multidate imagery are changes in surface moisture, texture and chemical composition, vegetation cover and the extent of aeolian activity. Inter-annual change phenomena are divisible into those restricted to marginal playa facies (sedimentation from sheetwash and alluvial fans, erosion from surface runoff and cliff retreat) and these are found in central playa facies which are related to the internal redistribution of water, salt and sediment

Grade Span Configuration and Academic Performance for Students in Poverty: A Texas Multiyear Analysis

Grade-span configuration refers to the range of grades within a school (Coladarci & Hancock, 2002). The debate over the benefits of one grade span configuration over the other has ensued for decades (Howley, 2002). Specific questions in this debate are (a) Which grade span configuration is most cost effective?; (b) Which grade span configuration yields the best academic achievement?; and (c) Which grade span configuration best meets the social and emotional needs of middle level children? (Howley, 2002)

Liability for Proceeding with Unfounded Litigation

The important issues for this Note are the meaning of good ground and the nature of the sanctions available in a given case.One can conceive of many ways in which a pleading could lack good ground. At one extreme, -the attorney might know that the facts alleged were untrue. \u27 Alternatively, the facts alleged, though not positively known to be untrue, might be based solely on speculation--as when the plaintiff, unsure who assaulted him, picked a name from the telephone directory on a hunch and sued that person. Between these egregious cases and the case in which the allegations have good ground by almost any definition lie innumerable gradations; at some point along this spectrum, the line of demarcation between lacking good ground and having good ground must be drawn. A separate but related question arises when the facts alleged, though not false or purely speculative, do not by any reasonable inference support the legal proposition on behalf of which they are offered. \u2

Approaches to Enhance Driver Situational Assessment Aids

Collision warning systems encounter a fundamental trade-off between providing the driver more time in which to respond and alerting the driver unnecessarily. The probability that a driver successfully avoids a hazard increases as the driver is provided more time and distance in which to identify the hazard and execute the most effective response. However, alerting the driver at earlier, more conservative thresholds increases the probability that the alerts are unnecessary, either because sensor error has falsely identified a hazard or because the environment has changed such that a hazard is no longer a threat. Frequent unnecessary alerts degrade alert effectiveness by reducing trust in the system. The human-factors issues pertaining to a forward collision warning system (FCWS) were analyzed using an Integrated Human-Centered Systems approach, from which two design features were proposed: multi-stage alerting, which alerts the driver at a conservative early threshold, in addition to a more serious late threshold; and directional alerting, which provides the driver information regarding the location of the hazard that prompted the alert activation. Alerting the driver earlier increases the probability of a successful response by conditioning the driver to respond more effectively if and when evasive action is necessary. Directional alerting decreases the amount of time required to identify the hazard, while promoting trust in the system by informing the driver of the cause of the alert activation. The proposed design features were incorporated into three FCWS configurations, and an experiment was conducted in which drivers were equipped with the systems and placed in situations in which a collision would occur if they did not respond. Drivers who were equipped with multi-stage and directional alerting were more effective at avoiding hazardous situations than drivers who were not provided early alerting. Drivers with early alerting tended to respond earlier and more consistently, which promoted more successful responses. Subjective feedback indicates that drivers experienced high levels of acceptance, confidence, and trust in multi-stage and directional alerting.This work was funded by a grant provided through the Ford-MIT Alliance

Practical analysis of polymers with depth varying compositions using Fourier transform infrared photoacoustic spectroscopy (plenary)

Fourier transform infrared photoacoustic spectroscopy can be used as a nondestructive method to probe the molecular composition of materials as a function of depth into the sample. This is done by varying the thickness of the surface layer being analyzed, which can be as great as some tens of micrometers, depending on optical and thermal properties.Computational methods are described to process photoacoustic amplitude and phase spectra for both semiquantitative and quantitative depth analyses. These methods are demonstrated on layered and gradient samples