834 research outputs found

    Ecosystem services delivered by small-scale wetlands

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    The benefits of small-scale wetlands have been largely overlooked, primarily because (a) such areas are considered problematic to manage, and (b) small wetlands fall outside the remit of most wetland inventories. The subsequent paucity of information prevents a comprehensive investigation of their properties and this must be addressed. Here we examine the evidence for the potential significance of small wetlands with regard to delivery of ecosystem services (ESs) and conclude that small wetlands often have a positive effect on their delivery, especially water quality, water regulation and biodiversity conservation. However these benefits can be offset by the emission of greenhouse gases. We suggest that, in future, wetlands should not be assessed on size alone, but rather in the context of both their location in the landscape and interaction with hydrological pathways. Furthermore, tools need to be developed to assess the type and efficiency of ESs delivered from all wetlands

    Robust Mapping of Incoherent Fiber-Optic Bundles

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    A method and apparatus for mapping between the positions of fibers at opposite ends of incoherent fiber-optic bundles have been invented to enable the use of such bundles to transmit images in visible or infrared light. The method is robust in the sense that it provides useful mapping even for a bundle that contains thousands of narrow, irregularly packed fibers, some of which may be defective. In a coherent fiber-optic bundle, the input and output ends of each fiber lie at identical positions in the input and output planes; therefore, the bundle can be used to transmit images without further modification. Unfortunately, the fabrication of coherent fiber-optic bundles is too labor-intensive and expensive for many applications. An incoherent fiber-optic bundle can be fabricated more easily and at lower cost, but it produces a scrambled image because the position of the end of each fiber in the input plane is generally different from the end of the same fiber in the output plane. However, the image transmitted by an incoherent fiber-optic bundle can be unscrambled (or, from a different perspective, decoded) by digital processing of the output image if the mapping between the input and output fiber-end positions is known. Thus, the present invention enables the use of relatively inexpensive fiber-optic bundles to transmit images

    Genetic Sampling of Palmer\u27s Chipmunks in the Spring Mountains, Nevada

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    Palmer\u27s chipmunk (Neotamias palmeri) is a medium-sized chipmunk whose range is limited to the higherelevation areas of the Spring Mountain Range, Nevada. A second chipmunk species, the Panamint chipmunk (Neotamias panamintinus), is more broadly distributed and lives in lower-elevation, primarily pinyon-juniper (Pinus monophylla-Juniperus osteosperma) habitat types. Panamint chipmunks are not closely related to Palmer\u27s, but field identification of the 2 species is unreliable. Palmer\u27s chipmunk is a species of concern in the state of Nevada and is listed by the International Union for Conservation of Nature (IUCN) as endangered. As such, conservation of Palmer\u27s chipmunks is a priority in the Spring Mountains National Recreation Area. We sampled putative Palmer\u27s chipmunks from 13 sites distributed across the Spring Mountains during 2010–2011. We removed Panamint chipmunks by using DNA-based identifications and then analyzed the genetic population structure of Palmer\u27s chipmunks by using a panel of 9 microsatellites. Of the 228 samples that were genotyped, 186 were Palmer\u27s; there was no evidence of hybridization between species. Four sites had exclusively Panamint chipmunks, 5 had exclusively Palmer\u27s chipmunks, and 3 had a mixture of the 2 species. In this study, Palmer\u27s chipmunks were exclusively captured at sites above 2400 m elevation, and Panamint chipmunks were exclusively captured at sites below 2200 m. Panamint chipmunks were trapped in areas typed as pinyon-juniper, but they were also trapped at sites typed as ponderosa pine (Pinus ponderosa) and mixed conifer. Both species were trapped at 3 sites; at all 3 sites, the lowerelevation traps contained Panamint chipmunks and the higher ones Palmer\u27s chipmunks. Population structure within Palmer\u27s chipmunks was minimal: heterozygosity was relatively high, and the populations displayed no signs of recent bottlenecks. Indications are that the distribution of Palmer\u27s chipmunk is limited to higher-elevation areas in the Spring Mountains, but within this area, Palmer\u27s chipmunk occurs as a single, large, well-connected, and stable population

    Structural and dynamical properties of liquid Si. An orbital-free molecular dynamics study

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    Several static and dynamic properties of liquid silicon near melting have been determined from an orbital free {\em ab-initio} molecular dynamics simulation. The calculated static structure is in good agreement with the available X-ray and neutron diffraction data. The dynamical structure shows collective density excitations with an associated dispersion relation which closely follows recent experimental data. It is found that liquid silicon can not sustain the propagation of shear waves which can be related to the power spectrum of the velocity autocorrelation function. Accurate estimates have also been obtained for several transport coefficients. The overall picture is that the dynamic properties have many characteristics of the simple liquid metals although some conspicuous differences have been found.Comment: 12 pages, 11 figure

    Optical Multi-Gas Monitor Technology Demonstration on the International Space Station

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    The International Space Station (ISS) employs a suite of portable and permanently located gas monitors to insure crew health and safety. These sensors are tasked with functions ranging from fixed mass spectrometer based major constituents analysis to portable electrochemical sensor based combustion product monitoring. An all optical multigas sensor is being developed that can provide the specificity of a mass spectrometer with the portability of an electrochemical cell. The technology, developed under the Small Business Innovation Research program, allows for an architecture that is rugged, compact and low power. A four gas version called the Multi-Gas Monitor was launched to ISS in November 2013 aboard Soyuz and activated in February 2014. The portable instrument is comprised of a major constituents analyzer (water vapor, carbon dioxide, oxygen) and high dynamic range real-time ammonia sensor. All species are sensed inside the same enhanced path length optical cell with a separate vertical cavity surface emitting laser (VCSEL) targeted at each species. The prototype is controlled digitally with a field-programmable gate array/microcontroller architecture. The optical and electronic approaches are designed for scalability and future versions could add three important acid gases and carbon monoxide combustion product gases to the four species already sensed. Results obtained to date from the technology demonstration on ISS are presented and discussed

    Subretinal pigment epithelial deposition of Drusen components including hydroxyapatite in a primary cell culture model

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    Purpose: Extracellular deposits containing hydroxyapatite, lipids, proteins, and trace metals that form between the basal lamina of the RPE and the inner collagenous layer of Bruch's membrane are hallmarks of early AMD. We examined whether cultured RPE cells could produce extracellular deposits containing all of these molecular components. Methods: Retinal pigment epithelium cells isolated from freshly enucleated porcine eyes were cultured on Transwell membranes for up to 6 months. Deposit composition and structure were characterized using light, fluorescence, and electron microscopy; synchrotron x-ray diffraction and x-ray fluorescence; secondary ion mass spectroscopy; and immunohistochemistry. Results: Apparently functional primary RPE cells, when cultured on 10-μm-thick inserts with 0.4-μm-diameter pores, can produce sub-RPE deposits that contain hydroxyapatite, lipids, proteins, and trace elements, without outer segment supplementation, by 12 weeks. Conclusions: The data suggest that sub-RPE deposit formation is initiated, and probably regulated, by the RPE, as well as the loss of permeability of the Bruch's membrane and choriocapillaris complex associated with age and early AMD. This cell culture model of early AMD lesions provides a novel system for testing new therapeutic interventions against sub-RPE deposit formation, an event occurring well in advance of the onset of vision loss

    Repositionable Versus Balloon-Expandable Devices for Transcatheter Aortic Valve Implantation in Patients With Aortic Stenosis.

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    The safety and effectiveness of the fully repositionable LOTUS valve system as compared with the balloon-expandable Edwards SAPIEN 3 prosthesis for the treatment of aortic stenosis has not been evaluated to date. All patients undergoing transcatheter aortic valve implantation with the Edwards SAPIEN 3 or the LOTUS valve system were included into the Swiss Transcatheter Aortic Valve Implantation Registry. An adjusted analysis was performed to compare the early clinical safety outcome according to the Valve Academic Research Consortium-2 definition. Between February 2014 and September 2015, 140 and 815 patients were treated with the LOTUS and the Edwards SAPIEN 3 valve, respectively. There was no difference in crude and adjusted analyses of the early safety outcome between patients treated with LOTUS (14.3%) and those treated with Edwards SAPIEN 3 (14.6%) (crude hazard ratio, 0.97; 95% CI, 0.61-1.56 [P=0.915]; adjusted hazard ratio, 1.03; 95% CI, 0.64-1.67 [P=0.909]). More than mild aortic regurgitation was <2% for both devices. A total of 34.3% of patients treated with LOTUS and 14.1% of patients treated with Edwards SAPIEN 3 required a permanent pacemaker (HR, 2.76; 95% CI, 1.97-3.87 [P<0.001]). The repositionable LOTUS valve system and the balloon-expandable Edwards SAPIEN 3 prosthesis appeared comparable in regard to the Valve Academic Research Consortium-2 early safety outcome, and the rates of more than mild aortic regurgitation were exceedingly low for both devices. The need for new permanent pacemaker implantation was more frequent among patients treated with the LOTUS valve

    Short and Efficient Syntheses of Protoberberine Alkaloids using Palladium-Catalyzed Enolate Arylation

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    A concise synthesis of the biologically active alkaloid berberine is reported, and a versatile palladium‐catalyzed enolate arylation is used to form the isoquinoline core. The overall yield of 50 % is a large improvement over the single, previous synthesis. By design, this modular route allows the rapid synthesis of other members of the protoberberine family (e.g., pseudocoptisine and palmatine) by substitution of the readily available aryl bromide and ketone coupling partners. Moreover, by combining enolate arylation with in situ functionalization, substituents can be rapidly and regioselectively introduced at the alkaloid C13 position, as demonstrated by the total synthesis of dehydrocorydaline. The avoidance of electrophilic aromatic substitution reactions to make the isoquinoline allows direct access to analogues possessing more varied electronic properties, such as the fluorine‐containing derivative synthesized here
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