1,468 research outputs found

    Variational calculation for the ground state of lithium and the QED corrections for Li-like ions

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    High-precision variational calculations using multiple basis sets in Hylleraas coordinates are presented for the 1s22s 2S state of lithium. The variational bound of -7.478 060 326(10) a.u. for the nonrelativistic energy is in good agreement with our revised experimental value of -7.47 806 034(20) a.u., thereby resolving a long-standing disrepancy. Two-electron calculations of the QED corrections are extended to three-electron systems and compared with other results. The comparison for Li-like ions up to U89+ suggests a simple interpretation for the \u27\u27screening of the Lamb shift\u27\u27 recently calculated by Cheng, Johnson, and Sapirstein [Phys. Rev. Lett. 66, 2960 (1991)]. © 1991 The American Physical Society

    Optical Coherence Tomography Used as a Modality to Delineate Basal Cell Carcinoma prior to Mohs Micrographic Surgery

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    Optical coherence tomography (OCT) has potential as a modality for in vivo imaging of non-melanoma skin cancer (NMSC). By allowing identification of sub-surface margins of NMSC lesions, the use of OCT could improve the rate of complete excision and reduce the average number of stages during Mohs micrographic surgery (MMS). The objective of this study was to use OCT to delineate the apparent sub-surface margins of NMSC lesions prior to their excision by MMS. Lesions were scanned with reference to a physical marker on the skin, and the apparent margins were then identified from the OCT images and marked on the skin. Photographs of these margins and the Mohs defect were correlated and compared. OCT appears capable of visualizing the transition from lesional to normal tissue. In this case study, margins marked by use of the OCT system before surgery exhibit excellent correlation with the MMS defect. OCT offers the promise of better outcomes by enabling accurate margin mapping of NMSC in advance of MMS. Priorities now are to demonstrate this capability in a larger study, and to understand clearly indications and contraindications for use

    NO2 column changes induced by volcanic eruptions

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    Nitrogen dioxide slant column amounts measured by ground-based remote sensing from Lauder, New Zealand (45 deg S) and Campbell Island (53 deg S) during the second half of 1991 and early 1992 show anomalously low values that are attributed to the effects of volcanic eruptions. It is believed that the eruptions of Mount Pinatubo in the Philippines in June 1991 and possibly Mount Hudson in Chile in August 1991 are responsible for the stratospheric changes, which first became apparent in July 1991. The effects in the spring of 1991 are manifested as a reduction in the retrieved NO2 column amounts from normal levels by 35 to 45 percent, and an accompanying increase in the overnight decay of NO2. The existence of an accurate long-term record of column NO2 from the Lauder site enables us to quantify departures from the normal seasonal behavior with some confidence. Simultaneous retrievals of column ozone agree well with Dobson measurements, confirming that only part of the NO2 changes can be attributed to a modification of the scattering geometry by volcanic aerosols. Other reasons for the observed behavior are explored, including the effects of stratospheric temperature increases resulting from the aerosol loading and the possible involvement of heterogeneous chemical processes

    Relationship between markers of malnutrition and clinical outcomes in older adults with cancer: systematic review, narrative synthesis and meta-analysis

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    © 2020, The Author(s). Malnutrition predicts poorer clinical outcomes for people with cancer. Older adults with cancer are a complex, growing population at high risk of weight-losing conditions. A number of malnutrition screening tools exist, however the best screening tool for this group is unknown. The aim was to systematically review the published evidence regarding markers and measures of nutritional status in older adults with cancer (age ≥ 70). A systematic search was performed in Ovid Medline, EMBASE, Web of Science, CINAHL, British Nursing Database and Cochrane CENTRAL; search terms related to malnutrition, cancer, older adults. Titles, abstracts and papers were screened and quality-appraised. Data evaluating ability of markers of nutritional status to predict patient outcomes were subjected to meta-analysis or narrative synthesis. Forty-two studies, describing 15 markers were included. Meta-analysis found decreased food intake was associated with mortality (OR 2.15 [2.03–4.20] p = < 0.00001) in univariate analysis. Prognostic Nutritional Index (PNI) was associated with overall survival (HR 1.89 [1.03–3.48] p = 0.04). PNI markers (albumin, total lymphocyte count) could be seen as markers of inflammation rather than nutrition. There a suggested relationship between very low body mass index (BMI)

    Consistency of Moderate to Vigorous Physical Activity in Middle School Physical Education

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    This study assessed the consistency of moderate to vigorous physical activity (MVPA) in a sample of middle school physical education lessons. Random intercept hierarchical linear regressions were employed to model the relationship between consistency of MVPA and independent variables, including lesson and teacher characteristics. Larger classes spent significantly more time in consistent MVPA in the absence of controlling for teacher characteristics. A significant interaction between class size and teacher experience suggests that experience may play a beneficial role in larger classes, and overall class size does not have to be a barrier to achieving high levels of MVPA

    Current Sheet and Reconnection Inflow-Outflow Observations During Solar Eruptions

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    Magnetic reconnection is widely accepted as a dominant source of energy during solar flares; however, observations of it have been indirect and/or incomplete. Using the suite of instruments available spanning wavelength space, we will provide observations and measurements of both the inputs and outputs predicted from reconnection in the form of inflows preceding outflows (i.e. supra-arcade downflows, supra-arcade downflowing loops, upflows, and disconnection events). We will also present evidence for current sheets through which reconnection is expected to occur and discuss current sheet motion during flare progression

    A novel microfluidic device capable of maintaining functional thyroid carcinoma specimens ex vivo provides a new drug screening platform

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    © 2019 The Author(s). Background: Though the management of malignancies has improved vastly in recent years, many treatment options lack the desired efficacy and fail to adequately augment patient morbidity and mortality. It is increasingly clear that patient response to therapy is unique to each individual, necessitating personalised, or 'precision' medical care. This demand extends to thyroid cancer; ~ 10% patients fail to respond to radioiodine treatment due to loss of phenotypic differentiation, exposing the patient to unnecessary ionising radiation, as well as delaying treatment with alternative therapies. Methods: Human thyroid tissue (n = 23, malignant and benign) was live-sliced (5 mm diameter × 350-500 μm thickness) then analysed or incorporated into a microfluidic culture device for 96 h (37 °C). Successful maintenance of tissue was verified by histological (H&E), flow cytometric propidium iodide or trypan blue uptake, immunohistochemical (Ki67 detection/ BrdU incorporation) and functional analysis (thyroxine [T4] output) in addition to analysis of culture effluent for the cell death markers lactate dehydrogenase (LDH) and dead-cell protease (DCP). Apoptosis was investigated by Terminal deoxynucleotidyl transferase dUTP nick end labelling (TUNEL). Differentiation was assessed by evaluation of thyroid transcription factor (TTF1) and sodium iodide symporter (NIS) expression (western blotting). Results: Maintenance of gross tissue architecture was observed. Analysis of dissociated primary thyroid cells using flow cytometry both prior to and post culture demonstrated no significant change in the proportion of viable cells. LDH and DCP release from on-chip thyroid tissue indicated that after an initial raised level of release, signifying cellular damage, detectable levels dropped markedly. A significant increase in apoptosis (p < 0.01) was observed after tissue was perfused with etoposide and JNK inhibitor, but not in control tissue incubated for the same time period. No significant difference in Ki-67 positivity or TTF1/NIS expression was detected between fresh and post-culture thyroid tissue samples, moreover BrdU positive nuclei indicated on-chip cellular proliferation. Cultured thyroid explants were functionally viable as determined by production of T4 throughout the culture period. Conclusions: The described microfluidic platform can maintain the viability of thyroid tissue slices ex vivo for a minimum of four days, providing a platform for the assessment of thyroid tissue radioiodine sensitivity/adjuvant therapies in real time
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