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Contemporary ice stream flow is directly linked to conditions at the ice/bed interface, yet this environment is logistically difficult to access. Instead, we investigate subglacial processes important for ice stream flow by studying tills on the deglaciated Antarctic continental shelf. We test currently-accepted hypotheses surrounding subglacial processes and till properties with a Ross Sea dataset. Till shear strengths indicate a continuum of simultaneous processes acting at the bed, rather than discrete ‘deformation’ and ‘lodgement’ end-members. We identify a threshold water content representing saturated pore spaces, leading to basal sliding and meltwater channelization. Based on observations of till properties relative to glacial landforms, we challenge the assumption that low shear strength is linked to intense deformation. Spatial variability in landform morphology reflects variability in deforming processes at the sub-ice stream scale and suggests a maximum deforming bed thickness of 2 m at the grounding line. Regional till properties generally correlate with seafloor geology and deglacial history; the western Ross Sea is characterized by higher and more variable shear strengths and water contents, while lower-shear strength till was preserved in the Eastern Basin. These observations inform till interpretation and provide context for deforming beds beneath the modern ice sheet and on glaciated continental shelves.
While our fascination with understanding the past is sufficient to warrant an increased focus on synthesis, solutions to important problems facing modern society require understandings based on data that only archaeology can provide. Yet, even as we use public monies to collect ever-greater amounts of data, modes of research that can stimulate emergent understandings of human behavior have lagged behind. Consequently, a substantial amount of archaeological inference remains at the level of the individual project. We can more effectively leverage these data and advance our understandings of the past in ways that contribute to solutions to contemporary problems if we adapt the model pioneered by the National Center for Ecological Analysis and Synthesis to foster synthetic collaborative research in archaeology. We propose the creation of the Coalition for Archaeological Synthesis coordinated through a U.S.-based National Center for Archaeological Synthesis. The coalition will be composed of established public and private organizations that provide essential scholarly, cultural heritage, computational, educational, and public engagement infrastructure. The center would seek and administer funding to support collaborative analysis and synthesis projects executed through coalition partners. This innovative structure will enable the discipline to address key challenges facing society through evidentially based, collaborative synthetic research.
The first starfish bed to be recognized from the Antilles is a lensoid body in the middle Miocene Grand Bay Formation of Carriacou, The Grenadines (West Indies). This unit was deposited in a turbidite basin in a region of active volcanism fed from one centre and preserves common deep-water taxa more typical of the Palaeozoic, such as crinoids and brachiopods. The starfish bed is a channel-fill deposit laid down in at least 150–200 m water depth, although the specimens may have been derived from shallower water. A goniasterid asteroid and an ophiacanthid ophiuroid have been recognized. The first articulated asteroid from the Antillean fossil record is Paragonaster(?) haldixoni sp. nov. In all skeletal features it appears close to the extant Atlantic species Paragonaster grandis H. L. Clark and P. subtilis (Perrier), but differs in having a single row of rectangular abactinal ossicles extending to the arm tip; these are longer than wide. The brittlestar, Ophiocamax ventosa sp. nov., is described on the basis of a fragmentary disc and arms from this deposit. The closest similarities are with the extant tropical western Atlantic species Ophiocamax hystrix Lyman and O. austera Verrill. However, the new species has thorns covering the entire surface of dorsal arm plates, while arm spines have a multitude of small thorns, loosely arranged in numerous rows and dorsal arm plate shape differs markedly. The occurrence of O. ventosa sp. nov. suggests that Ophiocamax has been a deep-sea taxon at least since the Miocene.
Desiccation following prolonged air exposure challenges survival of aquatic plants during droughts, water drawdowns, and overland dispersal. To improve predictions of plant response to air exposure, we observed the viability of vegetative fragments of 10 aquatic plant species (Cabomba caroliniana, Ceratophyllum demersum, Elodea canadensis, Egeria densa, Myriophyllum aquaticum, Myriophyllum heterophyllum, Myriophyllum spicatum, Potamogeton crispus, Potamogeton richardsonii, and Hydrilla verticillata) following desiccation. We recorded mass loss, desiccation rate, and plant fragment survival across a range of air exposures. Mass loss accurately predicted viability of aquatic plant fragments upon reintroduction to water. However, similar periods of air exposure differentially affected viability between species. Understanding viability following desiccation can contribute to predicting dispersal, improving eradication protocols, and disposing of aquatic plants following removal from invaded lakes or contaminated equipment.
Infection surveillance definitions for long-term care facilities (ie, the McGeer Criteria) have not been updated since 1991. An expert consensus panel modified these definitions on the basis of a structured review of the literature. Significant changes were made to the criteria defining urinary tract and respiratory tract infections. New definitions were added for norovirus gastroenteritis and Clostridum difficile infections.
Decline in executive function has been noted in the prodromal stage of Alzheimer's disease (AD) and may presage more global cognitive declines. In this prospective longitudinal study, five measures of executive function were used to predict subsequent global cognitive decline in initially nondemented older adults. Of 71 participants, 15 demonstrated significant decline over a 1-year period on the Dementia Rating Scale (Mattis, 1988) and the remaining participants remained stable. In the year before decline, the decline group performed significantly worse than the no-decline group on two measures of executive function: the Color-Word Interference Test (CWIT; inhibition/switching condition) and Verbal Fluency (VF; switching condition). In contrast, decliners and non-decliners performed similarly on measures of spatial fluency (Design Fluency switching condition), spatial planning (Tower Test), and number-letter switching (Trail Making Test switching condition). Furthermore, the CWIT inhibition-switching measure significantly improved the prediction of decline and no-decline group classification beyond that of learning and memory measures. These findings suggest that some executive function measures requiring inhibition and switching provide predictive utility of subsequent global cognitive decline independent of episodic memory and may further facilitate early detection of dementia. (JINS, 2012, 18, 118–127)
Nutrigenomics is the study of how constituents of the diet interact with genes, and their products, to alter phenotype and, conversely, how genes and their products metabolise these constituents into nutrients, antinutrients, and bioactive compounds. Results from molecular and genetic epidemiological studies indicate that dietary unbalance can alter gene–nutrient interactions in ways that increase the risk of developing chronic disease. The interplay of human genetic variation and environmental factors will make identifying causative genes and nutrients a formidable, but not intractable, challenge. We provide specific recommendations for how to best meet this challenge and discuss the need for new methodologies and the use of comprehensive analyses of nutrient–genotype interactions involving large and diverse populations. The objective of the present paper is to stimulate discourse and collaboration among nutrigenomic researchers and stakeholders, a process that will lead to an increase in global health and wellness by reducing health disparities in developed and developing countries.
Our experiments show boron-interstitial cluster dissolution is reduced during oxidation, a behavior not predicted by the current models. Both our experiments and others on the time dependence indicate the reactivation is coming from more than one cluster. Since oxidation induced interstitial injection reduces reactivation, one of the significant clusters has to release an interstitial release during dissolution. Recent ab-initio calculations provide a qualitatively different B clustering model, with two significant cluster species. Based on these energetics, we have developed a new physically based model that for the first time accounts for the experimentally observed cluster dissolution time and ambient dependence.
Anomalous B diffusion behavior is also observed in an investigation of Ge influence on B diffusion. Silicon wafers were subjected to a Si preamorphization implant (PAI), followed by Ge and B implants contained within the existing amorphous layer. The control sample received only Si PAI and B implant. Upon annealing, the peak of the B profile shifts towards the surface and increases in magnitude, exhibiting uphill diffusion. The control samples subjected to the same thermal processing exhibit TED, but no uphill diffusion behavior. This is consistent with the model of B diffusion in Si1−xGex, accounting for trapping of B at Ge sites through formation of GeB complex.
An accurate method to measure the four point probe (4PP) sheet resistance (Rs) of USJ Source-Drain structures is described. The new method utilizes Elastic Material probes (EM- probe) to form non-penetrating contacts to the silicon surface. The probe design is kinematic and the force is controlled to ensure elastic deformation of the probe material. The probe material is selected so that large direct tunneling currents can flow through the native oxide thereby forming a low impedance contact. Sheet resistance measurements on USJ implanted P+/N structures with SIMS junction depths as shallow as 15 nm have been measured. The sheet resistance values obtained with the new EM-probe 4PP method were found to be consistent with expectations. In this paper, the method will be demonstrated on a variety of implanted USJ structures.