171 research outputs found

    Beyond records and representations: inbetween writing in educational ethnography

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    Ethnographers are particularly interested in writing. They have paid particular attention to the practices of making field notes and to the ways in which their public texts represent those that they have encountered and studied. To date there has been less attention paid to the kinds of writing that used to make sense of experiences in the field. We call this inbetween writing. By examining our own processes of inbetween writing, and drawing on the work of James Clifford, we have produced a nine-part heuristic of inbetween writing. We argue that the heuristic could be used in research methods education to highlight the importance of writing to ethnographic sense-making and knowledge production

    Comparison of tools for the sustainability assessment of nanomaterials

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    Nanomaterials are becoming widely used in areas such as biomedical applications, food, environmental protection, energy production, information technology and agriculture. As such, more research has been conducted on their synthesis and manufacturing from a variety of feedstocks. However, concerns regarding their impact on human health and the environment leads researchers to conduct a variety of ‘sustainability’ assessments. The purpose of this paper was to review the current opinion of sustainability assessments concerning nanomaterials. Major assessment tools were reviewed including life cycle assessment, risk assessment and multi-criteria decision analysis, along with subcategories. The review found that each assessment tool did positively contribute to sustainability assessments, but each also had drawbacks of varying degrees. In particular, multi-criteria decision analysis provides the most relevant tool for conducting a sustainability assessment as it can handle criteria of any typology and provide multiple types of decision recommendations, including rankings, scores and classifications

    DESI Commissioning Instrument Metrology

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    The Dark Energy Spectroscopic Instrument (DESI) is under construction to measure the expansion history of the Universe using the Baryon Acoustic Oscillation technique. The spectra of 35 million galaxies and quasars over 14000 sq deg will be measured during the life of the experiment. A new prime focus corrector for the KPNO Mayall telescope will deliver light to 5000 fiber optic positioners. The fibers in turn feed ten broad-band spectrographs. We will describe the methods and results for the commissioning instrument metrology program. The primary goals of this program are to calculate the transformations and further develop the systems that will place fibers within 5um RMS of the target positions. We will use the commissioning instrument metrology program to measure the absolute three axis Cartesian coordinates of the five CCDs and 22 illuminated fiducials on the commissioning instrument

    An apparatus for verification of absolute calibration of quantum effiency for charge-coupled devices

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    The LBNL Microsystems Laboratory produces backside illuminated, high resistivity, p-channel, charge-coupled devices (CCDs). A system was developed to test the quantum efficiency (QE) of the CCDs; the percentage of electrons that are emitted from the CCD surface per amount of light that it\u27s exposed to. The QE system was designed and constructed to test CCDs of a much smaller size then what is currently produced. To continue testing, I redesigned the QE apparatus to make room for the new, larger size, CCDs while still preserving measurement accuracy. I removed the photodiode that formally sat alongside the CCD in the Dewar, and installed it in a separate container. Instead of the CCD and the photodiode taking flux measurements simultaneously, the processes are now preformed separately. The error caused by the separation has remained less than 1.78%

    Inducible ablation of CD11c+ cells to determine their role in skin wound repair

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    Wound healing in healthy skin requires a complex interplay between immune and non‐immune cells. In addition to their roles in infection control and cell debridement, leukocytes secrete factors to orchestrate the timing of the repair process via cross‐talk with epithelia. This critical role in wound timing is vital as failure to induce wound closure leads to debilitating chronic wounds susceptible to further infection and patient sepsis

    Frustrated Lewis pair (FLP)-catalyzed hydrogenation of aza-Morita–Baylis–Hillman adducts and sequential organo-FLP catalysis

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    Herein we report the metal-free diastereoselective frustrated Lewis pair (FLP)-catalyzed hydrogenation of aza-Morita–Baylis–Hillman (aza-MBH) adducts, accessing a diverse range of stereodefined β-amino acid derivatives in excellent isolated yields (28 examples, 89% average yield, up to 90:10 d.r.). Furthermore, sequential organo-FLP catalysis has been developed. An initial organocatalyzed aza-MBH reaction followed by in situ FLP formation and hydrogenation of the electron-deficient α,β-unsaturated carbonyl compounds can be performed in one-pot, using DABCO as the Lewis base in both catalytic steps

    Molecular cross sections for high resolution spectroscopy of super earths, warm Neptunes and hot Jupiters

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    High-resolution spectroscopy (HRS) has been used to detect a number of species in the atmospheres of hot Jupiters. Key to such detections is accurately and precisely modelled spectra for cross-correlation against the R ≳ 20 000 observations. There is a need for the latest generation of opacities which form the basis for high signal-to-noise detections using such spectra. In this study we present and make publicly available cross-sections for six molecular species, H2O, CO, HCN, CH4, NH3, and CO2 using the latest line lists most suitable for low- and high-resolution spectroscopy. We focus on the infrared (0.95–5 μm) and between 500 and 1500 K where these species have strong spectral signatures. We generate these cross-sections on a grid of pressures and temperatures typical for the photospheres of super-Earth, warm Neptunes, and hot Jupiters using the latest H2 and He pressure broadening. We highlight the most prominent infrared spectral features by modelling three representative exoplanets, GJ 1214 b, GJ 3470 b, and HD 189733 b, which encompass a wide range in temperature, mass, and radii. In addition, we verify the line lists for H2O, CO, and HCN with previous high-resolution observations of hot Jupiters. However, we are unable to detect CH4 with our new cross-sections from HRS observations of HD 102195 b. These high-accuracy opacities are critical for atmospheric detections with HRS and will be continually updated as new data become available

    Asymmetric triplex metallohelices with high and selective activity against cancer cells

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    Small cationic amphiphilic α-helical peptides are emerging as agents for the treatment of cancer and infection, but they are costly and display unfavourable pharmacokinetics. Helical coordination complexes may offer a three-dimensional scaffold for the synthesis of mimetic architectures. However, the high symmetry and modest functionality of current systems offer little scope to tailor the structure to interact with specific biomolecular targets, or to create libraries for phenotypic screens. Here, we report the highly stereoselective asymmetric self-assembly of very stable, functionalized metallohelices. Their anti-parallel head-to-head-to-tail ‘triplex’ strand arrangement creates an amphipathic functional topology akin to that of the active sub-units of, for example, host-defence peptides and ​p53. The metallohelices display high, structure-dependent toxicity to the human colon carcinoma cell-line HCT116 ​p53++, causing dramatic changes in the cell cycle without DNA damage. They have lower toxicity to human breast adenocarcinoma cells (MDA-MB-468) and, most remarkably, they show no significant toxicity to the bacteria methicillin-resistant Staphylococcus aureus and Escherichia coli. At a glanc
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