4,134 research outputs found

    If I Could Tell

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    In alternating first-person accounts, two primary and two secondary characters 'speak' the fictional narrative of If I Could Tell. As the title suggests, doubt is implicit in the narrative; there is no impediment, necessarily, to the story being told - 'I could tell it, if .. .' - but, rather, doubt about telling (from the characters' perspective) where the truth lies. An accumulation of first-person revelations forms, in four parts, an altogether more contestable version of the lives, thoughts and impulses of two 'siblings' Jessica (Jess) Morell and William (Willow) Morell/Osborne, a 'hitchhiker', Luna Fortune, and a nurse, Clare. In authoring themselves, each revealing a telling truth but misperceiving what is wholly true, they simultaneously create the narrative that, beyond their power, draws them together, then alienates them. As Luna says - essentially of the difficulty of deciding whether or not Willow is 'a nice guy' - 'My point being, you can't always tell how a story turns out for the person who's listening, because you can't tell what they're hearing, what the story means, because of stuff that's happened to them or stuff they know.' And the crisis of the novel lies at this nexus, the convergence of 'stuff that's happened' and 'stuff (the characters think) they know'. Plot and structure function together in exploring the limits and consequences of this intractability. Willow and Jess are the son and daughter of Frances and Alfred Morell, an airman reported missing in action in a distant conflict when they are infants, but a presence in their lives and their imaginations. After an obscure political upheaval compels them to move from the river settlement of their early years to the city to live with Alfred's unmarried brother, Geoffrey, the promise of a wholesome upbringing fades with a despairing Frances succumbing to drink. Through an accident of circumstance, her decline is associated with a serious injury Jess suffers in falling from a tree and, in the course of her recovery, the budding of an unnaturally intimate relationship with Willow. This intimacy comes to an incestuous climax on the night of their mother's burial, all but destroying their bond. They are estranged for some two decades. By the time they meet again as adults at Geoffrey's funeral, all the most important details of their relationship and their life story are found to be false or flawed - though neither of them knows the full extent. Only Jess knows that Willow is not in fact her brother, his own father having died at the time of her conception, and Willow is alone in knowing that Alfred Morell's fate is critically at odds with the lore they grew up with. As they begin their long journey home in Willow's car, each of them is privately transfixed by the risks and challenges of sorting truth from falsehood, and sealing the rapprochement they long for. Neither foresees the deranging impact of their glancing contact with Luna. The narrative is deliberately placed in an unnamed setting in the hope of freeing it from the burdens of a given history and the reflex associations that inevitably arise from assumptions of prior knowledge. The work is not entirely free, however, from a late-20th century backdrop of ideological contest and transition in which the tropes of personal and public accountability are discernible in the tension between the characters' private and social worlds. Their apparent willingness to discount the wider setting in favour of a more intimate order of interests seems often delusional, and is arguably akin to the author's evasive intentions. The three most prominent characters all have torments to reckon with, each of them in its way originating in the churn of History, though seeming capable of being weighed on a subjective scale. Yet it is probably the social context that is, if murkily, the agency of dissonance in the characters' relations. It falls to Willow to discover - or to show, without necessarily being conscious of the demonstration - that personal and public pasts converge ineluctably, with unpredictable consequences. If I Could Tell is the distillation of a long process of reading and thinking, and four years of writing and extensive revision. The fifth and final draft reveals significant departures from the structure and character development of the first. Influences vary widely, but in thinking through the themes of engaging or evading the historical process, of placing the individual in the muddle if not always the middle, certain texts stand out for their imaginative reach and technical achievements, among them W G Sebald's Austerlitz, Gunter Grass's The Tin Drum, J M Coetzee's Life and Times of Michael K, Tolstoy's novella-length short story Haji Murat, Graham Greene's The Quiet American, Alain Robbe-Grillers The Erasers, Philip Roth's American Pastoral and, more recently, Martin Amis's House of Meetings. Throughout, I found myself returning to the notion expressed by the writer in Andre Gide's The Counterfeiters, who says of his book, emerging 'quite different from what I had been trying to invent', that 'I wish it now to run freely, according to its bent, sometimes swift, sometimes slow; I choose not to foresee its windings'. Its appeal as a writerly credo comes, eventually, with the necessarily humble acknowledgement that doubt stimulated by perceptive supervision is an indispensable accompaniment

    Defect chemistry and vacancy concentration of luminescent europium doped ceria nanoparticles by solvothermal method

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    Pure phase and europium-doped ceria nanocrystals have been synthesized by a single step simple solvothermal process. Different spectroscopic, diffractive, and microscopic techniques were used to determine the morphology, size, crystal structure, and phase of all the samples. Electron energy loss spectroscopy (EELS) for elemental mapping confirmed that good solid solutions were formed and that the particles had a homogeneous distribution of europium. The defect chemistry was more complex than might be expected with the incorporation of each Eu3+ ion resulting in the production of an anion vacancy since the doping results in charge compensating (i.e., for Eu3+) anion vacancies as well as vacancies due to oxygen removal from the crystallite surface. Variations in nanoparticles dimension and lattice parameters were measured as a function of dopant concentrations and their variations explained. The band gap of the samples could be tailored by the doping. The doped samples were found to be luminescent due to the substitution of Ce4+ ions in the cubic symmetric lattice by the dopant ions. The thermal stability of the fluorescence properties was also investigated

    Natural Wormholes as Gravitational Lenses

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    Visser has suggested traversable 3-dimensional wormholes that could plausibly form naturally during Big Bang inflation. A wormhole mouth embedded in high mass density might accrete mass, giving the other mouth a net *negative* mass of unusual gravitational properties. The lensing of such a gravitationally negative anomalous compact halo object (GNACHO) will enhance background stars with a time profile that is observable and qualitatively different from that recently observed for massive compact halo objects (MACHOs) of positive mass. We recommend that MACHO search data be analyzed for GNACHOs.Comment: 4 pages; plus 4 figures; ReV_TeX 3.0; DOE/ER/40537-001/NPL94-07-01

    A positron annihilation spectroscopic investigation of europium-doped cerium oxide nanoparticles

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    Doping in ceria (CeO2) nanoparticles with europium (Eu) of varying concentrations (0, 0.1, 0.5, 
, 50 atom%) is studied using complementary experimental techniques and novel observations were made during the investigation. The immediate observable effect was a distinct reduction in particle sizes with increasing Eu concentration attributed to the relaxation of strain introduced due to the replacement of Ce4+ ions by Eu3+ ions of larger radius. However, this general trend was reversed in the doping concentration range of 0.1–1 atom% due to the reduction of Ce4+ to Ce3+ and the formation of anion vacancies. Quantum confinement effects became evident with the increase of band gap energy when the particle sizes reduced below 7–8 nm. Positron annihilation studies indicated the presence of vacancy type defects in the form of vacancy clusters within the nanoparticles. Some positron annihilation was also seen on the surface of crystallites as a result of diffusion of thermalized positrons before annihilation. Coincidence Doppler broadening measurements indicated the annihilation of positrons with electrons of different species of atoms and the characteristic S–W plot showed a kink-like feature at the particle sizes where quantum confinement effects began

    Non-Invasive Raman Tomographic Imaging of Canine Bone Tissue

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    Raman spectroscopic diffuse tomographic imaging has been demonstrated for the first time. It provides a noninvasive, label-free modality to image the chemical composition of human and animal tissue and other turbid media. This technique has been applied to image the composition of bone tissue within an intact section of a canine limb. Spatially distributed 785-nm laser excitation was employed to prevent thermal damage to the tissue. Diffuse emission tomography reconstruction was used, and the location that was recovered has been confirmed by micro-computed tomography (micro-CT) images. With recent advances, diffuse tomography shows promise for in vivo clinical imaging.1, 2 In principle, algorithms developed for fluorescence imaging in tissue can be applied to Raman signals. Although the Raman effect is weaker than fluorescence, the scattered signal is detectable, and thus tomography is achievable. Here we demonstrate the first diffuse tomography reconstructions based on Raman scatter. Raman mapping and imaging are well-established techniques for examining material surfaces.3 Subsurface mapping of simple planar objects was reported recently4, 5 using fiber optic probes with spatially separated injection and collection fibers.6 Noninvasive measurements of bone Raman spectra were demonstrated at depths of5mm role= presentation \u3e5mm below the skin.5 Bone is promising for Raman tomography because the spectra are rich in compositional information,7 which reflects bone maturity and health. Spectroscopically measured bone composition changes have been correlated with aging8 and susceptibility to osteoporotic fracture.9 The Raman spectrum of bone mineral is easily distinguished from the spectra of proteins and other organic tissue constituents, facilitating recovery of even weak signals by multivariate techniques. Assessments of bone quantity and quality are essential to detect and monitor fracture risk and fracture healing with disease or injury. Common sites for fracture with osteoporosis are the spine, proximal femur, and distal radius. Stress fractures are most frequently seen in the weight-bearing sites of the tibia and metatarsals. Fracture risk depends on bone geometry, architecture, and material properties, as well as the nature of applied load (magnitude, rate, and direction). As a result, noninvasive imaging and nondestructive analysis methods have been developed to assess many of these bone attributes that are increasingly important to clinical practice and basic research in orthopedics.10 Current clinical in vivo methods include dual-energy x-ray absorptiometry (DXA), quantitative computed tomography (QCT), magnetic resonance imaging (MRI), ultrasound, and most recently, high-resolution peripheral QCT. Ex vivo analyses of bone specimens from patients or animals have also utilized these and other techniques. In this study, we couple micro-computed tomography (micro-CT) and diffuse optical tomography with Raman spectroscopy to recover spatial and composition information from bone tissue ex vivo. We demonstrate the first reconstruction-based recovery of Raman signals through thick tissues to yield molecular information about subsurface bone tissue. Reconstructions from transcutaneous Raman measurements are challenging, because layers of skin, muscle, fat, and connective tissue lie over the bone sites of interest. These layers have different optical properties and thus variably scatter and polarize the injected light. We chose a canine model because of specimen availability and a bone size similar to human bone. We selected the tibia, a site that is clinically important and has relatively few overlying soft tissues. Measurements were made on the medial surface, where the only additional optical barrier is the crural extensor retinaculum ligament. The canine hind limb was harvested from an animal euthanized in an approved (UCUCA) University of Michigan study. The section of the limb distal to the knee was excised and scanned using in vivo micro-CT (eXplore Locus RS, GE Healthcare, Ontario, Canada). The tibia was scanned at80kV role= presentation \u3e80kV and 450ÎŒA role= presentation \u3e450ÎŒA with an exposure time of 100ms role= presentation \u3e100ms using a 360-deg scan technique. The image was reconstructed at a 93-ÎŒm role= presentation \u3e93-ÎŒm voxel resolution [Fig. 1a ]

    Ground-layer wavefront reconstruction from multiple natural guide stars

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    Observational tests of ground layer wavefront recovery have been made in open loop using a constellation of four natural guide stars at the 1.55 m Kuiper telescope in Arizona. Such tests explore the effectiveness of wide-field seeing improvement by correction of low-lying atmospheric turbulence with ground-layer adaptive optics (GLAO). The wavefronts from the four stars were measured simultaneously on a Shack-Hartmann wavefront sensor (WFS). The WFS placed a 5 x 5 array of square subapertures across the pupil of the telescope, allowing for wavefront reconstruction up to the fifth radial Zernike order. We find that the wavefront aberration in each star can be roughly halved by subtracting the average of the wavefronts from the other three stars. Wavefront correction on this basis leads to a reduction in width of the seeing-limited stellar image by up to a factor of 3, with image sharpening effective from the visible to near infrared wavelengths over a field of at least 2 arc minutes. We conclude that GLAO correction will be a valuable tool that can increase resolution and spectrographic throughput across a broad range of seeing-limited observations.Comment: 25 pages, 8 figures, to be published in Astrophys.

    Synthesis and stability of IR-820 and FITC doped silica nanoparticles

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    Fluorescent silica nanoparticles (NPs) have potential in biomedical applications as diagnostics and traceable drug delivery agents. In this study, we have synthesized fluorescent dye grafted silica NPs in two step process. First, a stable method to synthesize various sizes of silica NPs ranging from 20 to 52, 95, 210 and 410 nm have been successfully demonstrated. Secondly, as-synthesized silica NPs are readily grafted with some fluorescent dyes like IR-820 and fluorescein isothiocyanate (FITC) dyes by simple impregnation method. IR-820 and FITC dyes are ‘activated’ by (3-mercaptopropyl)trimethoxysilane (MPTMS) and (3-aminopropyl)triethoxysilane (APTS) respectively prior to the grafting on silica NPs. UV–vis spectroscopy is used to test the stability of dye grafted silica NPs. The fluorescent dye grafted silica NPs are quite stable in aqueous solution. Also, a new type of dual dye-doped hybrid silica nanoparticles has been developed. The combination of microscopic and spectroscopic techniques shows that the synthesis parameters have significant effects on the particle shape and size and is tuneable from a few nanometers to a few hundred nanometers. The ability to create size controlled nanoparticles with associated (optical) functionality may have significant importance in bio-medical imaging

    Electrochemistry at nanoscale electrodes : individual single-walled carbon nanotubes (SWNTs) and SWNT-templated metal nanowires

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    Individual nanowires (NWs) and native single-walled carbon nanotubes (SWNTs) can be readily used as well-defined nanoscale electrodes (NSEs) for voltammetric analysis. Here, the simple photolithography-free fabrication of submillimeter long Au, Pt, and Pd NWs, with sub-100 nm heights, by templated electrodeposition onto ultralong flow-aligned SWNTs is demonstrated. Both individual Au NWs and SWNTs are employed as NSEs for electron-transfer (ET) kinetic quantification, using cyclic voltammetry (CV), in conjunction with a microcapillary-based electrochemical method. A small capillary with internal diameter in the range 30–70 ÎŒm, filled with solution containing a redox-active mediator (FcTMA+ ((trimethylammonium)methylferrocene), Fe(CN)64–, or hydrazine) is positioned above the NSE, so that the solution meniscus completes an electrochemical cell. A 3D finite-element model, faithfully reproducing the experimental geometry, is used to both analyze the experimental CVs and derive the rate of heterogeneous ET, using Butler–Volmer kinetics. For a 70 nm height Au NW, intrinsic rate constants, k0, up to ca. 1 cm s–1 can be resolved. Using the same experimental configuration the electrochemistry of individual SWNTs can also be accessed. For FcTMA+/2+ electrolysis the simulated ET kinetic parameters yield very fast ET kinetics (k0 > 2 ± 1 cm s–1). Some deviation between the experimental voltammetry and the idealized model is noted, suggesting that double-layer effects may influence ET at the nanoscale

    Quantum Inequalities and Singular Energy Densities

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    There has been much recent work on quantum inequalities to constrain negative energy. These are uncertainty principle-type restrictions on the magnitude and duration of negative energy densities or fluxes. We consider several examples of apparent failures of the quantum inequalities, which involve passage of an observer through regions where the negative energy density becomes singular. We argue that this type of situation requires one to formulate quantum inequalities using sampling functions with compact support. We discuss such inequalities, and argue that they remain valid even in the presence of singular energy densities.Comment: 18 pages, LaTex, 2 figures, uses eps

    The Inheritance of Resistance Alleles in Multiple Sclerosis

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    Multiple sclerosis (MS) is a complex trait in which alleles at or near the class II loci HLA-DRB1 and HLA-DQB1 contribute significantly to genetic risk. HLA-DRB1*15 and HLA-DRB1*17-bearing haplotypes and interactions at the HLA-DRB1 locus increase risk of MS but it has taken large samples to identify resistance HLA-DRB1 alleles. In this investigation of 7,093 individuals from 1,432 MS families, we have assessed the validity, mode of inheritance, associated genotypes, and the interactions of HLA-DRB1 resistance alleles. HLA-DRB1*14-, HLA-DRB1*11-, HLA-DRB1*01-, and HLA-DRB1*10-bearing haplotypes are protective overall but they appear to operate by different mechanisms. The first type of resistance allele is characterised by HLA-DRB1*14 and HLA-DRB1*11. Each shows a multiplicative mode of inheritance indicating a broadly acting suppression of risk, but a different degree of protection. In contrast, a second type is exemplified by HLA-DRB1*10 and HLA-DRB1*01. These alleles are significantly protective when they interact specifically in trans with HLA-DRB1*15-bearing haplotypes. HLA-DRB1*01 and HLA-DRB1*10 do not interact with HLA-DRB1*17, implying that several mechanisms may be operative in major histocompatibility complex–associated MS susceptibility, perhaps analogous to the resistance alleles. There are major practical implications for risk and for the exploration of mechanisms in animal models. Restriction of antigen presentation by HLA-DRB1*15 seems an improbably simple mechanism of major histocompatibility complex–associated susceptibility
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