1,990 research outputs found

    The late-time development of the Richtmyer–Meshkov instability

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    Measurements have been made of the growth by the Richtmyer–Meshkov instability of nominally single-scale perturbations on an air/sulfur hexafluoride (SF6) interface in a large shock tube. An approximately sinusoidal shape is given to the interface by a wire mesh which supports a polymeric membrane separating the air from the SF6. A single shock wave incident on the interface induces motion by the baroclinic mechanism of vorticity generation. The visual thickness delta of the interface is measured from schlieren photographs obtained singly in each run and in high-speed motion pictures. Data are presented for delta at times considerably larger than previously reported, and they are tested for self-similarity including independence of initial conditions. Four different initial amplitude/wavelength combinations at one incident shock strength are used to determine the scaling of the data. It is found that the growth rate decreases rapidly with time, ddelta/dt[proportional]t–p (i.e., delta[proportional]t1–p), where 0.67<~p<~0.74 and that a small dependence on the initial wavelength lambda0 persists to large time. The larger value of the power law exponent agrees with the result of the late-time-decay similarity law of Huang and Leonard [Phys. Fluids 6, 3765–3775 (1994)]. The influence of the wire mesh and membrane on the mixing process is assessed

    A novel methodology for in vivo endoscopic phenotyping of colorectal cancer based on real-time analysis of the mucosal lipidome: a prospective observational study of the iKnife

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    Background: This pilot study assessed the diagnostic accuracy of rapid evaporative ionization mass spectrometry (REIMS) in colorectal cancer (CRC) and colonic adenomas. Methods: Patients undergoing elective surgical resection for CRC were recruited at St. Mary’s Hospital London and The Royal Marsden Hospital, UK. Ex vivo analysis was performed using a standard electrosurgery handpiece with aspiration of the electrosurgical aerosol to a Xevo G2-S iKnife QTof mass spectrometer (Waters Corporation). Histological examination was performed for validation purposes. Multivariate analysis was performed using principal component analysis and linear discriminant analysis in Matlab 2015a (Mathworks, Natick, MA). A modified REIMS endoscopic snare was developed (Medwork) and used prospectively in five patients to assess its feasibility during hot snare polypectomy. Results: Twenty-eight patients were recruited (12 males, median age 71, range 35–89). REIMS was able to reliably distinguish between cancer and normal adjacent mucosa (NAM) (AUC 0.96) and between NAM and adenoma (AUC 0.99). It had an overall accuracy of 94.4 % for the detection of cancer versus adenoma and an adenoma sensitivity of 78.6 % and specificity of 97.3 % (AUC 0.99) versus cancer. Long-chain phosphatidylserines (e.g., PS 22:0) and bacterial phosphatidylglycerols were over-expressed on cancer samples, while NAM was defined by raised plasmalogens and triacylglycerols expression and adenomas demonstrated an over-expression of ceramides. REIMS was able to classify samples according to tumor differentiation, tumor budding, lymphovascular invasion, extramural vascular invasion and lymph node micrometastases (AUC’s 0.88, 0.87, 0.83, 0.81 and 0.81, respectively). During endoscopic deployment, colonoscopic REIMS was able to detect target lipid species such as ceramides during hot snare polypectomy. Conclusion: REIMS demonstrates high diagnostic accuracy for tumor type and for established histological features of poor prognostic outcome in CRC based on a multivariate analysis of the mucosal lipidome. REIMS could augment endoscopic and imaging technologies for precision phenotyping of colorectal cancer

    Comparative Analysis of Zeolite Y From Nigerian Clay and Standard Grade

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    Zeolite Y catalyst with silica/alumina mola‹· ntio of 4.70 was synthesized from Elefun (Nigel"ia) clay unde‹· hydwthe‹·mal tJ·eatment of calcined kaolin with aqueous NaOH at atmosphel"ic p‹·essm·e. This pape‹· descl"ibed the p‹·epantion of zeolite Y catalyst fmm metakaolin of quality Elefun kaolin by ageing at 34oC fo‹· 7days, and then n·ystallized at lOOoC fm· 24 hom·s. The synthesized zeolite NaY was modified by exchanging with NH4Cl to obtain its hydwgen fo‹·m with silica/alumina ntio of 3.18. Both developed and standa1·d zeolite Y catalyst we1·e then chanctel"ized by a val"iety of physicochemical methods, including XRD, XRF spectwscope. The mm·phologies we1·e examined using SEM. Similar results we1·e obtained, thus confi‹·ming the synthesis of zeolite Y

    Response to Letter to the Editor

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/89557/1/j.1399-0012.2011.01437.x.pd

    Factors associated with positive attitudes toward organ donation in Arab Americans

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/86866/1/j.1399-0012.2010.01382.x.pd

    Modelling of content-aware indicators for effective determination of shot boundaries in compressed MPEG videos

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    In this paper, a content-aware approach is proposed to design multiple test conditions for shot cut detection, which are organized into a multiple phase decision tree for abrupt cut detection and a finite state machine for dissolve detection. In comparison with existing approaches, our algorithm is characterized with two categories of content difference indicators and testing. While the first category indicates the content changes that are directly used for shot cut detection, the second category indicates the contexts under which the content change occurs. As a result, indications of frame differences are tested with context awareness to make the detection of shot cuts adaptive to both content and context changes. Evaluations announced by TRECVID 2007 indicate that our proposed algorithm achieved comparable performance to those using machine learning approaches, yet using a simpler feature set and straightforward design strategies. This has validated the effectiveness of modelling of content-aware indicators for decision making, which also provides a good alternative to conventional approaches in this topic

    Monitoring Seagrass within the Reef 2050 Integrated Monitoring and Reporting Program: final report of the Seagrass Expert Group

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    Seagrass is widely distributed throughout the Great Barrier Reef (the Reef), with a documented 35,000 square kilometres and a potential habitat area of 228,300 square kilometres. Seagrass meadows occur in many different environmental conditions, both within and beyond the impact of flood plumes, and are common in areas of high anthropogenic activity, such as ports and areas adjacent to urban centres. Many processes and services that maintain the exceptional values of the Reef occur in seagrass meadows. To provide the services that support these values seagrass habitats include a range of species, growth forms and benthic landscapes, that respond to pressures in different ways. In many cases seagrasses also modify their environments to improve environmental conditions on the Reef. Seagrasses vary spatially and temporally in their distribution and abundance across the Reef, occurring in different water quality types (estuaries, coastal, reefal and offshore) and at different water depths (intertidal, shallow subtidal, deep water). The diversity of potential seagrass habitats is one reason they support so many of the environmental services and values of the Great Barrier Reef World Heritage Area (World Heritage Area), including: habitat for crabs, prawns and fish –– supporting recreational and commercial fishing; primary food resource for species of conservation significance (dugong, green turtles, migratory shore birds); shoreline stabilisation by binding sediment to slow erosion; water clarity improvement, by promoting the settlement of fine particulate matter; and providing a natural carbon sink. To deliver the seagrass components of the knowledge system required to deliver Reef 2050 Long-Term Sustainability Plan (Reef 2050 Plan) reporting and other management activities, there will need to be modifications and enhancements made to the current seagrass monitoring programs. The Drivers, Pressures, State, Impact, Response (DPSIR) framework was used to facilitate the identification of linkages between the pressures on seagrass, state of the seagrass, the impact a decline in seagrass would have on community values, and the responses management agencies can take to mitigate loss of values. We have also defined twelve seagrass habitat types that occur on the Reef, identified by a matrix of water body type and water depth. The seagrasses occurring in each habitat are exposed to different pressures and require different management actions (responses) to protect and enhance the values of the community and Reef ecosystems. The proposed monitoring program has three spatial and temporal scales, with each scale providing different information (knowledge) to support resilience-based management of the Reef. 1. Habitat assessment: will occur across the Reef at all sites where seagrass has a potential of occurring. It will determine seagrass abundance, species composition and spatial extent of each habitat type within the World Heritage Area. This scale will be focused on supporting future outlook reports, but will also provide information for operational and strategic management and contribute towards other reports. 2. Health assessment: will take place at representative regional sites, for each habitat type. These sites will provide managers with annual and seasonal trends in seagrass condition and resilience at a regional scale for each habitat. This scale will provide higher temporal detail (i.e. at least annually) of seagrass condition and resilience, supporting tactical, operational and strategic management applications. This scale will provide the majority of information for regional/catchment report cards and the assessment of management effectiveness at a catchment wide scale. It will also contribute important trends in condition and resilience to Outlook reports and other communication products with more frequent reporting. 3. Process monitoring: will take place at the fewest number of sites, nested within habitat and health assessment sites. Due to the time-consuming and complex nature of these measurements the sampling sites will be chosen to focus on priority knowledge gaps. This scale will provide managers with information on cause-and-effect relationships and linkages between different aspects of the Reef’s processes and ecosystems. This scale will include measures of seagrass resilience (for example, feedback loops, recovery time after disturbance, history of disturbance and thresholds for exposure to pressures). The attributes measured at these sites will also provide confidence to managers regarding the impact a change in seagrass condition is likely to have on other values of the Reef (for example, fish, megafauna, coral, Indigenous heritage, and human dimensions). To ensure that future seagrass monitoring delivers the information required to report on the Reef 2050 Plan and meets the other knowledge requirements of managers, a spatially balanced random sampling design needs to be implemented on the Reef. Existing monitoring programs can and should be integrated into this design. However, current seagrass monitoring programs do not provide a balanced assessment of seagrass condition across the entire Reef, hence are not suitable to meet the Reef 2050 Plan reporting requirements and many other management information needs. Existing sites within current monitoring are focused on habitat types that are intertidal and shallow sub-tidal and lie close to the coast. These habitats have been previously selected because they face high levels of cumulative anthropogenic risk and therefore have higher levels of management demand for information. The current sites are likely to decline more rapidly, in response to catchment run-off and other anthropogenic pressures, than the average for seagrass meadows across the entire Reef. They also have a greater potential to show improvements from Reef catchment management actions that reduce pollution associated with run-off. This report sets out the framework for a recommended new seagrass monitoring program, highlighting the substantial improvements in knowledge and confidence this new program will deliver, and provides a scope for the statistical design work required to support implementation of this program

    Non-asymptotically flat, non-AdS dilaton black holes

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    We show that previously known non-asymptotically flat static black hole solutions of Einstein-Maxwell-dilaton theory may be obtained as near-horizon limits of asymptotically flat black holes. Specializing to the case of the dilaton coupling constant α2=3\alpha^2 = 3, we generate from the non-asymptotically flat magnetostatic or electrostatic black holes two classes of rotating dyonic black hole solutions. The rotating dyonic black holes of the ``magnetic'' class are dimensional reductions of the five-dimensional Myers-Perry black holes relative to one of the azimuthal angles, while those of the ``electric'' class are twisted dimensional reductions of rotating dyonic Rasheed black strings. We compute the quasi-local mass and angular momentum of our rotating dyonic black holes, and show that they satisfy the first law of black hole thermodynamics, as well as a generalized Smarr formula. We also discuss the construction of non-asymptotically flat multi-extreme black hole configurations.Comment: Minor corrections. 2 references added. To appear in Physical Review

    Choroidal vascularity map in unilateral central serous chorioretinopathy: A comparison with fellow and healthy eyes

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    Background: To map the choroidal vascularity index and compare two eyes in patients with unilateral central serous chorioretinopathy (CSCR). Methods: This was a retrospective, observa-tional study performed in patients with unilateral CSCR. Choroidal thickness (CT) and Choroidal vascularity index (CVI) were measured and mapped in various zones according to the early treatment diabetic retinopathy (ETDRS) grid. Results: A total of 20 CSCR patients (20 study and 20 fellow eyes) were included in the study. Outer nasal region CT was seen to be significantly lower than central CT (p = 0.042) and inner nasal CT (p = 0.007); outer ring CT was significantly less than central (p = 0.04) and inner ring (p = 0.01) CT in CSCR eyes. On potting all the CVI values against the corresponding CT values, a positive correlation was seen in CSCR eyes (r = 0.54, p &lt; 0.01), which was slightly weaker in fellow eyes (r = 0.3, p &lt; 0.01) and a negative correlation was seen in healthy eyes (r = −0.262, p &lt; 0.01). Conclusions: Correlation between CVI and CT was altered in CSCR eyes as compared to fellow and normal eyes with increasing CVI towards the center of the macula and superiorly in CSCR eyes

    The early Neolithic of Iraqi Kurdistan: current research at Bestansur, Shahrizor Plain

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    Human communities made the transition from hunter-foraging to more sedentary agriculture and herding at multiple locations across Southwest Asia through the Early Neolithic period (ca. 10,000-7000 cal. BC). Societies explored strategies involving increasing management and development of plants, animals, materials, technologies, and ideologies specific to each region whilst sharing some common attributes. Current research in the Eastern Fertile Crescent is contributing new insights into the Early Neolithic transition and the critical role that this region played. The Central Zagros Archaeological Project (CZAP) is investigating this transition in Iraqi Kurdistan, including at the earliest Neolithic settlement so far excavated in the region. In this article, we focus on results from ongoing excavations at the Early Neolithic site of Bestansur on the Shahrizor Plain, Sulaimaniyah province, in order to address key themes in the Neolithic transition
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