8,877 research outputs found

    Anatomy and origin of authochthonous late Pleistocene forced regression deposits, east Coromandel inner shelf, New Zealand: implications for the development and definition of the regressive systems tract

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    High-resolution seismic reflection data from the east Coromandel coast, New Zealand, provide details of the sequence stratigraphy beneath an autochthonous, wave dominated inner shelf margin during the late Quaternary (0-140 ka). Since c. 1 Ma, the shelf has experienced limited subsidence and fluvial sediment input, producing a depositional regime characterised by extensive reworking of coastal and shelf sediments during glacio-eustatic sea-level fluctuations. It appears that only one complete fifth-order (c. 100 000 yr) depositional sequence is preserved beneath the inner shelf, the late Pleistocene Waihi Sequence, suggesting any earlier Quaternary sequences were mainly cannibalised into successively younger sequences. The predominantly Holocene-age Whangamata Sequence is also evident in seismic data and modern coastal deposits, and represents an incomplete depositional sequence in its early stages of formation. A prominent aspect of the sequence stratigraphy off parts of the east Coromandel coast is the presence of forced regressive deposits (FRDs) within the regressive systems tract (RST) of the late Pleistocene Waihi Sequence. The FRDs are interpreted to represent regressive barrier-shoreface sands that were sourced from erosion and onshore reworking of underlying Pleistocene sediments during the period of slow falling sea level from isotope stages 5 to 2 (c. 112-18 ka). The RST is volumetrically the most significant depositional component of the Waihi Sequence; the regressive deposits form a 15-20 m thick, sharp-based, tabular seismic unit that downsteps and progrades continuously across the inner shelf. The sequence boundary for the Waihi Sequence is placed at the most prominent, regionally correlative, and chronostratigraphically significant surface, namely an erosional unconformity characterised in many areas by large incised valleys that was generated above the RST. This unconformity is interpreted as a surface of maximum subaerial erosion generated during the last glacial lowstand (c. 18 ka). Although the base of the RST is associated with a prominent regressive surface of erosion, this is not used as the sequence boundary as it is highly diachronous and difficult to identify and correlate where FRDs are not developed. The previous highstand deposits are limited to subaerial barrier deposits preserved behind several modern Holocene barriers along the coast, while the transgressive systems tract is preserved locally as incised-valley fill deposits beneath the regressive surface of erosion at the base of the RST. Many documented late Pleistocene RSTs have been actively sourced from fluvial systems feeding the shelf and building basinward-thickening, often stacked wedges of FRDs, for which the name allochthonous FRDs is suggested. The Waihi Sequence RST is unusual in that it appears to have been sourced predominantly from reworking of underlying shelf sediments, and thus represents an autochthonous FRD. Autochthonous FRDs are also present on the Forster-Tuncurry shelf in southeast Australia, and may be a common feature in other shelf settings with low subsidence and low sediment supply rates, provided shelf gradients are not too steep, and an underlying source of unconsolidated shelf sediments is available to source FRDs. The preservation potential of such autochthonous FRDs in ancient deposits is probably low given that they are likely to be cannibalised during subsequent sea-level falls

    Optically controlled resonance energy transfer:Mechanism and configuration for all-optical switching

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    In a molecular system of energy donors and acceptors, resonance energy transfer is the primary mechanism by means of which electronic energy is redistributed between molecules, following the excitation of a donor. Given a suitable geometric configuration it is possible to completely inhibit this energy transfer in such a way that it can only be activated by application of an off-resonant laser beam: this is the principle of optically controlled resonance energy transfer, the basis for an all-optical switch. This paper begins with an investigation of optically controlled energy transfer between a single donor and acceptor molecule, identifying the symmetry and structural constraints and analyzing in detail the dependence on molecular energy level positioning. Spatially correlated donor and acceptor arrays with linear, square, and hexagonally structured arrangements are then assessed as potential configurations for all-optical switching. Built on quantum electrodynamical principles the concept of transfer fidelity, a parameter quantifying the efficiency of energy transportation, is introduced and defined. Results are explored by employing numerical simulations and graphical analysis. Finally, a discussion focuses on the advantages of such energy transfer based processes over all-optical switching of other proposed forms. © 2008 American Institute of Physics

    United States Air Force Officer Manpower Planning Problem via Approximate Dynamic Programming

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    The United States Air Force (USAF) is concerned with managing its officer corps to ensure sufficient personnel for mission readiness. Manpower planning for the USAF is a complex process which requires making decisions about accessions. Uncertainty about officer retention complicates such decisions. We formulate a Markov decision process model of the Air Force officer manpower planning problem (AFO-MPP) and utilize a least squares approximate policy iteration algorithm as an approximate dynamic programming (ADP) technique to attain solutions. Computational experiments are conducted on two AFO-MPP instances to compare the performance of the policy determined with the ADP algorithm to a benchmark policy. We find that the ADP algorithm performs well for the basis functions selected, providing policies which reduce soft costs associated with shortages and surpluses in the force

    Homeostasis and Polymorphism in Vernal Development of Chaoborus Americanus

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/119057/1/ecy19735461247.pd

    VISUAL CONTROL OF HIGH-VELOCITY FOOT-TARGETING TASKS IN NOVICE AND EXPERT PERFORMERS

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    The visual regulation of step length and duration during target-directed locomotion was examined in relation to gait mode, approach velocity, obstacle task, and practice during a series of four experiments. Visual regulation was found to decrease in novice performers but increase in expert performers when approach velocity increased. The aptitude of expert performers is partly due to their ability to visually regulate for a greater time and distance during the approach, resulting in more accurate final foot placement. The speed/accuracy trade-off may be a mechanism that protects novice performers from harm whilst negotiating obstacles in the everyday environment

    THE APPROACH, VAULTING PERFORMANCE, AND JUDGE’S SCORE IN WOMEN’S ARTISTIC GYMNASTICS

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    The approach step, hurdle, and round-off length characteristics of women’s vaulting were examined in relation to post-flight performance and judge’s score during five trials for five gymnasts. Two reference strips with alternating 50cm black and white intervals were placed on either side of the approach area. One 50Hz panning camera filmed the approach, with two stationary 250Hz cameras filming the post-flight vaulting performance. Two qualified judges viewed each trial and provided a performance score. A significant correlation was found between velocity during visual control of the approach, post-flight time (p≤0.01) and judge’s score (p≤0.01). Specifically, increased approach velocity leads to an increase in round-off velocity (p≤0.01), resulting in a short high velocity take-off from the board (p≤0.01)

    It’s gender Jim, but not as we know it 
 A critical review of constructions of gendered knowledge of the global south

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    This article explores how research helps construct a certain type of ‘gender’ knowledge that arises from, informs and reinforces ‘instrumentalist’ gendered policy perspectives on development of the Global South. It uses a case study of research funded under the ESRC-DFID Joint Fund for Poverty Alleviation which awarded 122 grants amounting to £66.2 million (around US$88 million) between 2005 and 2015. From a systematic review of the awards a typology of gender inclusion and exclusion was constructed that found 60% of all awards mentioned gender or included some level of gender analysis. The subsequent synthesis of the evidence suggested that in only 30% of all awards was the gendered knowledge produced central to the study and/or focused on better understanding gender roles, relations and identities. Applying a Feminist Institutionalist lens, the study highlights how institutional ideas around gender are reflected in the funding call specifications, and in turn influence how researchers ‘engendered’ their research, and the type of gendered knowledge produced. It finds much of the new gendered knowledge produced out of the Joint Fund emerged from non-gender focused research often produced by non-gendered researchers. It suggests that as gender becomes mainstreamed into research, and as more researchers ‘do gender’, so research becomes, conversely, less ‘gendered’. The ‘new’ gender knowledge produced may then merely evidence existing institutional policy positions rather than advance the policy agenda

    Effect of pressure on the partial equivalent volume of salts in seawater

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    The effect of pressure on the partial equivalent volumes of salts of the major ions in 35%, seawater at 10 and 25°C was determined for applied pressures of 400 and 1000 bars from measurements of the change in solution compression with salt concentration...

    The Creation of a Next-Generation Cancer Treatment Using Photodynamic Therapy

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    Photodynamic therapy (PDT) is a treatment for various health disorders, including cancer, that uses a photosensitive agent and light. Unlike other cancer treatments, PDT is a focused treatment that kills cancerous cells without harming the surrounding tissues. When a photosensitive agent is administered, it accumulates in the tumor as it binds to low density lipoproteins. When the tumor is exposed to a specific wavelength of light, the photosensitive agent is activated; this results in the release singlet oxygen, which kills the tumor. The objective of this research was to synthesize and characterize a novel photosensitive agent, H2TPP-2A2E. Purification of the novel be used in the next generation of photodynamic therapy. material was achieved using column chromatography. In addition, IR, UV-vis, and NMR spectroscopies were used to characterize the product, and purity was determined using HPLC. After determining that our product was refined, cytotoxicity testing in light and dark conditions revealed that the novel H2TPP-2A2E, could potentially be used in the next generation of photodynamic therapy

    ZnTPPEA as a Potential Photosensitizer in Photodynamic Therapy

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    Photodynamic therapy (PDT) is an emerging treatment that is used against certain types of cancer and other diseases. It functions using a photosensitizer in the presence of light that contributes to cell death in the desired tissues. This research centered on the development of a novel water-soluble porphyrin that could be utilized as a photosensitizer. Using ethanolamine the resulting compound, ZnTPP-EA, was created. Purification and characterization was carried out. The ZnTPP-EA was tested on the A549 lung cancer cell line using an MTT assay under light and dark conditions to assess the compound\u27s effectiveness as a photosensitizer for PDT
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