1,477 research outputs found

    Can one invasion lead to another? Niche space and the future of Southwestern U.S. riparian zones

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    Effects of Biomass Loss on the Seasonal Variability in Storage Compounds of Pterygophora Californica

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    The stalked kelp, Pterygophora californica, is an important secondary canopy- forming species of coastal kelp forests from Alaska to Baja. It has long been thought that due to its long-lived, perennial thallus structures, seasonal growth and reproduction, and compound translocation capabilities, Pterygophora creates nutrient reserves. However, many aspects of Pterygophora have been understudied, including this theorized storage mechanism. This study addressed its storage capabilities by identifying nutrient compartmentalization, monitoring thalli over time, and examining allocation through biomass removals. Compartmentalization was observed among thallus regions of control thalli. All regions of the stipe and the reproductive sori had a higher mean %C than the holdfast, sporophyll, and vegetative blade regions. Isotopic fractionation illustrated that on average, the vegetative blade and sporophylls were more enriched in 13C than the lower stipe, potentially suggesting that the high bulk carbon in the stipe is a reserve that allocates carbohydrates to the blades. However, carbon fractionation due to photosynthesis and respiration was not measured, and therefore it is unknown how much impact those processes have on the 13C enrichment among thallus regions. A pattern of decreasing mean %N was seen from the base to top of the thallus. The holdfast region on average was the region of highest %N, and lowest C:N. A pattern of increasing C:N was seen from the base to the top of the stipe, and the ratio in the sporophylls was more similar to the lower and mid stipe regions than to the other blade tissues. Seasonality of nutrient compartmentalization in the thallus was not seen, meaning time had no effect on the chemical distribution among thallus regions (ā€œcompartmentsā€). However, some seasonal variability of chemicals was observed for the thallus as a whole and within thallus regions individually. The only thallus regions that were significantly affected by blade manipulations were the lower, mid, and upper stipe. Changes within these regions were significantly impacted by the removal of sporophylls. Overall, the evident patterns in this study have uncovered a consistent nitrogen reserve in the holdfast, carbon reserve in the stipe, and allocation of carbon to the blades

    The status of Habitats Directive Annex I saltmarsh habitats, transition zones and spartina species in England

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    On unmodified soft sediment coastlines, of which there are long lengths especially on the English east and south coasts, there should be a wide transitional zone between tidal areas and full terrestrial land. The conditions in this zone result in a rich and distinctive range of habitats. There are two saltmarsh habitats listed in Annex I of the Habitats Directive within this zone (H1420 Mediterranean and thermo-Atlantic halophilous scrubs and H1320 Spartina swards,Spartinion maritimae) reflecting its importance for nature conservation. At the time work for this project was started in 2012, the conservation status of these habitats was reported as ā€˜unfavourable, bad and deterioratingā€™. Due to construction of artificial sea defences, these zones are now much reduced in extent and distribution and are under threat from a range of factors. This project aims to provide an inventory and description of Annex I saltmarsh habitats and transitional vegetation in England. This will help to update future reporting on conservation status. The outcomes will also help improve understanding of the underpinning processes which can be used in design to improve the potential for recreating these elements of saltmarshes as part of intertidal restoration schemes. The project also provides an up to date assessment of Spartina alterniflora stands in the Solent SAC through review and field survey for 2012

    Recipients of electric-powered indoor/outdoor wheelchairs provided by a National Health Service: A cross-sectional study

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    This is the post-print version of the final paper published in Archives of Physical Medicine and Rehabilitation. The published article is available from the link below. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. Copyright @ 2013 by the American Congress of Rehabilitation Medicine.OBJECTIVE: To describe the characteristics, across all ages, of powered wheelchair users and the assistive technology prescribed by a regional specialist wheelchair service DESIGN: Cross-sectional study SETTING: Regional wheelchair service provided to those fulfilling strict eligibility criteria by a National Health Service serving a population of 3 million. PARTICIPANTS: 544 Electric Powered Indoor/outdoor wheelchair (EPIOC) users. INTERVENTIONS: Not applicable MAIN OUTCOME MEASURES: Demographic, clinical/diagnostic details of EPIOC recipients including pain, (kypho)scoliosis and ventilators. Technical features including specialised (adaptive) seating (SS), tilt in space (TIS), and modified control systems. Factors were related to age groups: 1 (0-15), 2 (16-24), 3 (25-54), 4 (55-74) and 5 (75+). RESULTS: 262 men mean age 41.7 (range 8-82, sd 20.7) and 282 women mean age 47.2 (range 7-92, sd 19.7) years were studied. Neurological/neuromuscular conditions predominated (81%) with cerebral palsy (CP) (18.9%) and multiple sclerosis (16.4%). Conditions presenting at birth or during childhood constituted 39%. 99 had problematic pain, 83 a (kypho)scoliosis and 11 used ventilators. SS was provided to 169 users (31%), the majority had CP or muscular dystrophy. TIS was used by 258 (53%). Younger people were more likely to receive TIS than older ones. Only 92 had SS and TIS, mean age 29 (range 8-72, sd 17.8) years. 52 used modified control systems. CONCLUSIONS: The diversity of EPIOC users across age and diagnostic groups is shown. Their complex interrelationships with these technical features of EPIOC prescription are explored. Younger users were more complex due to age-related changes. This study provides outcomes of the EPIOC prescription for this heterogeneous group of very severely disabled people

    Policy Gaps and Opportunities: A Systematic Review of Autism Spectrum Disorder and Criminal Justice Intersections

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    LAY ABSTRACT: The number of people with autism spectrum disorder has increased, and as this population ages, research is showing high rates of contact with the criminal justice system among this group. Social and communication differences that autistic individuals experience can act as a risk factor during these interactions, as shown by public reports of negative and violent encounters between autistic individuals and the law enforcement. There is a clear need for evidence-based strategies to reduce high rates of contact and to improve outcomes when an interaction occurs. This article provides a systematic review of research on autism spectrum disorder and criminal justice system to compile this evidence base. The Preferred Reporting Items for Systematic Reviews and Meta-Analysis structure was used to identify 89 articles after searching six databases. The Sequential Intercept Model describes the criminal justice system as different stages, or intercepts, that are connected, and the Sequential Intercept Model serves as an overall framework to organize the included articles. Articles were analyzed to identify research themes at each intercept, which offer guidance for policy and program changes that support equitable justice for autistic individuals

    A Centennial Record of Paleosalinity Change in the Tidal Reaches of the Potomac and Rappahannock Rivers, Tributaries to Chesapeake Bay

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    Gravity and push cores from the Potomac and Rappahannock Rivers (Virginia Tidewater) were collected from central and proximal estuarine zones with known seasonal salinity stratification. The lowermost microfossil associations in the cores comprise alternating ostracode populations of Cyprideis salebrosa and Cytheromorpha. This microfossil association gives way to an oligohaline association dominated by the freshwater ostracode Darwinula stevensoni. Stable oxygen isotope values (Ī“18O) of Rapphannock Cyprideis salebrosa are highly variable ranging between -6.6 to -3.2ā€° VPDB. Ī“18O values for Potomac Cytheromorpha fuscata range from -8.2 to -3.2ā€° VPDB. Positive excursions in Ī“18O values are synchronous with population peaks for both Cyprideis and Cytheromorpha indicative of increased marine influence and/or higher salinities. Microfossil paleoecology coupled with oxygen isotope values record a marked shift towards gradual freshening and deterioration of the salinity structure in the tidal tributaries during the mid-to late 19th century. We attribute these trends to both decadal climate trends and aggressive land use practices in the Chesapeake Bay watershed during the late 19th to middle 20th centuries

    Variation in the organization and subunit composition of the mammalian pyruvate dehydrogenase complex E2/E3BP core assembly

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    The final version of this article is available at the link below.Crucial to glucose homoeostasis in humans, the hPDC (human pyruvate dehydrogenase complex) is a massive molecular machine comprising multiple copies of three distinct enzymes (E1ā€“E3) and an accessory subunit, E3BP (E3-binding protein). Its icosahedral E2/E3BP 60-meric ā€˜coreā€™ provides the central structural and mechanistic framework ensuring favourable E1 and E3 positioning and enzyme co-operativity. Current core models indicate either a 48E2+12E3BP or a 40E2+20E3BP subunit composition. In the present study, we demonstrate clear differences in subunit content and organization between the recombinant hPDC core (rhPDC; 40E2+20E3BP), generated under defined conditions where E3BP is produced in excess, and its native bovine (48E2+12E3BP) counterpart. The results of the present study provide a rational basis for resolving apparent differences between previous models, both obtained using rhE2/E3BP core assemblies where no account was taken of relative E2 and E3BP expression levels. Mathematical modelling predicts that an ā€˜averageā€™ 48E2+12E3BP core arrangement allows maximum flexibility in assembly, while providing the appropriate balance of bound E1 and E3 enzymes for optimal catalytic efficiency and regulatory fine-tuning. We also show that the rhE2/E3BP and bovine E2/E3BP cores bind E3s with a 2:1 stoichiometry, and propose that mammalian PDC comprises a heterogeneous population of assemblies incorporating a network of E3 (and possibly E1) cross-bridges above the core surface.This work was partly supported by EPSRC (under grants GR/R99393/01 and EP/C015452/1)
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