1,137 research outputs found
Giant Kelp Genetic Monitoring Before and After Disturbance Reveals Stable Genetic Diveristy in Southern California
Given the impacts of climate change and other anthropogenic stressors on marine systems, there is a need to accurately predict how species respond to changing environments and disturbance regimes. The use of genetic tools to monitor temporal trends in populations gives ecologists the ability to estimate changes in genetic diversity and effective population size that may be undetectable by traditional census methods. Although multiple studies have used temporal genetic analysis, they usually involve commercially important species, and rarely sample before and after disturbance. In this study, we use newly collected samples, coupled with previously characterized microsatellite data to assess the genetic consequences of disturbance in several populations of giant kelp (Macrocystis pyrifera) in the Southern California Bight. We performed a pre- and post-disturbance microsatellite analysis to look at changes over a 10-year period, which included the 2015/16 El Nino Southern Oscillation event. We used canopy biomass estimated by remote sensing (Landsat) to quantify the extent of disturbance to kelp beds, and sea surface temperature data to understand how kelp was pushed towards its temperature limits during this period. Despite prolonged periods with decreased canopy at several sites, no changes in genetic structure and allelic richness was observed. We discuss how deep refugia of subsurface sporophytes and cryptic microscopic life stages could have kept genetic diversity through disturbance, with the latter being the only possible mechanism in one shallow continental site. Given the increasing effects of climate change and uncertainty in modeling impacts of species with cryptic life history stages, we suggest further investigation to reveal the role such stages play in species resilience
Balancing the scales : the standard of reasons required in commercial arbitration and litigation in Australia
Evidence for Past Subduction Earthquakes at a Plate Boundary with Widespread Upper Plate Faulting: Southern Hikurangi Margin, New Zealand
At the southern Hikurangi margin, New Zealand, we use salt marsh stratigraphy, sedimentology, micropaleontology, and radiocarbon dating to document evidence of two earthquakes producing coseismic subsidence and (in one case) a tsunami over the past 1000 yrs. The earthquake at 520-470 yrs before present (B.P.) produced 0.25 +/- 0.1 m of subsidence at Big Lagoon. The earthquake at 880-800 yrs B.P. produced 0.45 +/- 0.1 m of subsidence at Big Lagoon and was accompanied by a tsunami that inundated >= 360 m inland with a probable height of >= 3.3 m. Distinguishing the effects of upper plate faulting from plate interface earthquakes is a significant challenge at this margin. We use correlation with regional upper plate paleoearthquake chronologies and elastic dislocation modeling to determine that the most likely cause of the subsidence and tsunami events is subduction interface rupture, although the older event may have been a synchronous subduction interface and upper plate fault rupture. The southern Hikurangi margin has had no significant (M > 6.5) documented subduction interface earthquakes in historic times, and previous assumptions that this margin segment is prone to rupture in large to great earthquakes were based on seismic and geodetic evidence of strong contemporary plate coupling. This is the first geologic evidence to confirm that the southern Hikurangi margin ruptures in large earthquakes. The relatively short-time interval between the two subduction earthquakes (similar to 350 yrs) is shorter than in current seismic-hazard models.GNSEQC Biennial ProjectNew Zealand Natural Hazards Research Platform and Foundation for Research Science and TechnologyInstitute for Geophysic
Estimating the Racial Composition of Groups of Faces: An Ensemble Other-Race Effect
In the current study we presented Asian and Caucasian
participants with brief displays containing 16 faces and asked
them to judge whether there were more Asians or Caucasians
present. We varied the physical proportion of each race in the
display using the method of constant stimuli and obtained
estimates of the point of subjective equality (PSE) by fitting
cumulative normal functions to individual data. Consistent
with recent findings on “ensemble” face processing,
participants were able to make group estimates quite
accurately. However, the estimates from the two groups of
participants did not overlap, with Asian participants
appearing to weight other-race faces more heavily than
Caucasian participants. To our knowledge, this is the first
demonstration of an other-race effect in the context of groups
of faces
Foraging activity and colony thermoregulation of the honey bee Apis mellifera following exposure to the organophosphate pesticide chlorpyrifos
Honey bees (Apis mellifera L.) are important pollinators and yet, an increasing number of reports suggest honey bee populations worldwide are in decline. Pollinators face many environmental stressors, including exposure to pesticides. Chlorpyrifos is an organophosphate pesticide that is used extensively in New Zealand. This thesis examines whether exposing bees to chlorpyrifos, applied to a forage crop at a concentration recommended by the manufacturer, alters honey bee foraging activity, or colony temperature.
A 1.26ha crop of Phacelia tanacetifolia was planted in the Ida Valley of Central Otago, New Zealand, and sprayed with 0.20kg a.i/ha of Lorsban 50EC. The spray event occurred in early January 2017, the height of the austral summer. Honey bee colonies were introduced to the crop either, prior to the spray event or at intervals thereafter. Colonies exposed to pesticide were compared with colonies located on control (untreated) sites.
HiveMind monitors, a satellite based measurement system, were used to provide a real time count of foraging activity and a record of internal hive temperatures in all colonies. Activity and temperature measurements were taken every three hours over a 4 month period.
Significant changes in maximum activity levels and in-hive temperature were identified in all colonies. The results suggest these changes were mainly driven by shifts in forage availability and external temperature over time. There was no clear evidence linking chlorpyrifos exposure to either the decline in activity levels, or to changes in colony temperature. However this may be due to the length of the experiment which may have required a longer study period to observe pesticide effects, or the effects were masked due to other environmental factors. Further work is required to ascertain whether in the longer term, chlorpyrifos alters colony productivity
A crematorium
Thesis (M.Arch.) Massachusetts Institute of Technology. Dept. of Architecture, 1955.Accompanying drawings held by MIT Museum.Includes bibliographies.by William Beckley Hayward.M.Arch
Quantification of Residual Stress from Photonic Signatures of Fused Silica
A commercially available grey-field polariscope (GFP) instrument for photoelastic examination is used to assess impact damage inflicted upon the outer-most pane of Space Shuttle windows made from fused silica. A method and apparatus for calibration of the stress-optic coefficient using four-point bending is discussed. The results are validated on known material (acrylic) and are found to agree with literature values to within 6%. The calibration procedure is then applied to fused-silica specimens and the stress-optic coefficient is determined to be 2.43 +/- 0.54 x 10(exp -12)/Pa. Fused silica specimens containing impacts artificially made at NASA's Hypervelocity Impact Technology Facility (HIT-F), to simulate damage typical during space flight, are examined. The damage sites are cored from fused silica window carcasses and examined with the GFP. The calibrated GFP measurements of residual stress patterns surrounding the damage sites are presented. Keywords: Glass, fused silica, photoelasticity, residual stres
Blending for student engagement: lessons learned for the MOOCs and beyond
The purpose of this ongoing, three-year action research study is to explore the digital challenges of student engagement in higher education within the experimental platform of blended learning. Research questions examine the role of digital innovation in supporting diverse learners, as well as building meaningful connections with technology for undergraduate teacher education students. Results from qualitative data collected through instructor journals and field notes and student mid-term and exit surveys during year one, indicate blended learning can be effective for modelling how to use technology to shift learners towards more active agency. The immediacy of the localised university classroom delivered a viable research setting for digital experimentation, while providing a significant lived experience for undergraduates to springboard their future technological practices with K–12 students. Four pedagogical opportunities for digital intentionality in virtual spaces emerged during data analysis and are shared as considerations for future innovation: (1) designing digital resources, (2) scaffolding student learning, (3) learner customisation, and (4) promoting the lived experience. Lessons learned could be effective in helping develop higher quality educational experiences for on-campus students, as well as scaffolding greater engagement in online formats involving more global populations (e.g., massive online open courses – MOOCs)
Bridge and ballast interaction at a viaduct structural expansion joint on a high speed railway
Proving MEMS technologies for smarter railway infrastructure
Quantifying how railway track responds to passing trains in terms of displacement, velocity or acceleration, can provide insights into both the performance and the condition of the track. A number of trackside monitoring technologies have been shown to be capable of providing this information; however these are primarily research tools and tend to be costly hence actual deployments are relatively limited in scope. To assess systematically the changing health of railway track, more cost-effective continuous approaches to monitoring are required. Micro electrical mechanical systems (MEMS) are commonplace sensors in consumer electronics, low cost and can be used to measure acceleration. Thus they have the potential to provide the kind of data required to assess railway track behaviour at a much lower cost and in an environmentally robust small deployment package. However confidence in the quality of the data is required. This paper discusses the criteria for the selection of MEMS devices for this application. Laboratory trials and direct comparison of trackside measurements with well-established monitoring techniques demonstrate the effectiveness of the selected MEMS devices, and show their potential for use in continuous monitoring schemes to evaluate changes in track performance. The paper thus provides evidence that these kinds of low cost technologies are suitable for railway applications, building confidence in their use and enabling their adoption in self-monitoring smart infrastructure
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