2,774 research outputs found

    Can we predict expected adenoma weight preoperatively with reference to the correlation of preoperative biochemical tests with parathyroid adenoma weight?

    Get PDF
    Background: Primary hyperparathyroidism is a prevalent disease with proven benefits for appropriately selected patients who undergo parathyroidectomy. The ability to accurately predict expected single adenoma gland weight as the cause based on preoperative biochemical tests could improve cure rates in a minimally invasive approach. Objective: To assess the correlation between parathyroid weight and preoperative parathyroid hormone and calcium levels in patients with primary hyperparathyroidism with a solitary adenoma and determine if these could be used to predict expected parathyroid weight. Methods: Patients with primary hyperparathyroidism who underwent curative parathyroidectomy from 2013 to 2018 was retrospectively analysed. Results: There is a strong positive correlation r = 0.602 between preoperative PTH levels with respect to parathyroid weight (p \u3c 0.001). There was a moderate correlation r = 0.474 between preoperative adjusted Calcium and PTH weight (p \u3c 0.001). An algorithm was developed to calculate predicted weight of a single adenoma but when tested against cases with hyperplasia and double adenomas during the period, the variability of predicted weight meant it was impossible to differentiate between the causes. Hyperplasia was excluded and 95% of double adenomas excluded however, when parathyroid weight exceeded 1200 mg. Conclusion: There is a strong correlation between preoperative PTH levels and calcium levels with parathyroid weight. The large variability of predicted parathyroid weight however, precludes the use of biochemical tests alone preoperatively in being able to differentiate between a single adenoma, double adenoma or hyperplasia as the cause in primary hyperparathyroidism. At parathyroid predicted weights above 1200 mg however, all cases of hyperplasia, and 95% of double adenomas excluded

    A simple method for improving the specificity of anti-methyl histone antibodies

    Get PDF
    Antibodies differentiating between the mono-, di- and trimethylated forms of specific histone lysine residues are a critical tool in epigenome research, but show variable specificity, potentially limiting comparisons across studies and between samples. Using trimethyl histone H3 lysine 4 (H3K4me3)-a mark enriched at transcription start sites (TSS) of active genes-as an example, we describe how simple co-incubation with synthetic peptide of the K4me2 modification leads to increased specificity for K4me3 and a much sharper peak distribution proximal to TSS following chromatin immunoprecipitation and massively parallel sequencing (ChIP-Seq)

    A scaling law for distinct electrocaloric cooling performance in low-dimensional organic, relaxor and anti-ferroelectrics.

    Get PDF
    Electrocaloric (EC) materials show promise in eco-friendly solid-state refrigeration and integrable on-chip thermal management. While direct measurement of EC thin-films still remains challenging, a generic theoretical framework for quantifying the cooling properties of rich EC materials including normal-, relaxor-, organic- and anti-ferroelectrics is imperative for exploiting new flexible and room-temperature cooling alternatives. Here, we present a versatile theory that combines Master equation with Maxwell relations and analytically relates the macroscopic cooling responses in EC materials with the intrinsic diffuseness of phase transitions and correlation characteristics. Under increased electric fields, both EC entropy and adiabatic temperature changes increase quadratically initially, followed by further linear growth and eventual gradual saturation. The upper bound of entropy change (∆Smax) is limited by distinct correlation volumes (V cr ) and transition diffuseness. The linearity between V cr and the transition diffuseness is emphasized, while ∆Smax = 300 kJ/(K.m3) is obtained for Pb0.8Ba0.2ZrO3. The ∆Smax in antiferroelectric Pb0.95Zr0.05TiO3, Pb0.8Ba0.2ZrO3 and polymeric ferroelectrics scales proportionally with V cr-2.2, owing to the one-dimensional structural constraint on lattice-scale depolarization dynamics; whereas ∆Smax in relaxor and normal ferroelectrics scales as ∆Smax ~ V cr-0.37, which tallies with a dipolar interaction exponent of 2/3 in EC materials and the well-proven fractional dimensionality of 2.5 for ferroelectric domain walls

    The physical origins of gas in the circumgalactic medium using observationally-motivated TNG50 mocks

    Full text link
    Absorbers in the spectrum of background objects probe the circumgalactic medium (CGM) surrounding galaxies, but its physical properties remain unconstrained. We use the cosmological hydrodynamical simulation TNG50 to statistically trace the origins of HI Ly-α\alpha absorbers around galaxies at z=0.5z = 0.5 with stellar masses ranging from 108^8 to 1011^{11} M⊙_\odot. We emulate observational CGM studies by considering all gas within a line of sight velocity range of ±500\pm 500 km s−1^{-1} from the central, to quantitatively assess the impact of other galaxy haloes and overdense gas in the IGM that intersect sightlines. The impact of satellites to the total absorber fraction is most significant at impact parameters 0.5Rvir<b<Rvir0.5 R_{\rm vir} < b < R_{\rm vir} and satellites with masses below typical detection limits (M∗<108M_* < 10^8 M⊙_\odot) account for 10 (40) per cent of absorbers that intersect any satellite bound to 101010^{10} and 101110^{11} (109)(10^9) M⊙_\odot centrals. After confirming outflows are more dominant along the minor axis, we additionally show that at least 20 per cent of absorbers exhibit no significant radial movement, indicating that absorbers can also trace quasi-static gas. The metallicity of absorbers also depends on the azimuthal angle, but this signal is largely driven by enriched inflowing and quasi-static gas. Our work shows that determining the stellar mass of galaxies at zabsz_{\rm abs} is essential to constrain the physical origin of the gas traced in absorption, which in turn is key to characterising the kinematics and distribution of gas and metals in the CGM.Comment: 23 pages, 13 figures. Accepted for publication in MNRA

    Investigations on Epoxy-Carbamate Foams Modified with Different Flame Retardants for High-Performance Applications

    Get PDF
    In transport sectors such as aviation, automotive and railway, materials combining a high lightweight potential with high flame retardant properties are in demand. Polymeric foams are suitable materials as they are lightweight, but often have high flammability. This study focuses on the influence of different flame retardants on the burning behavior of Novolac based epoxy foams using Isophorone Diamine carbamate (B-IPDA) as dual functional curing and blowing agent. The flame retardant properties and possible modifications of these foams are systematically investigated. Multiple flame retardants, representing different flame retardant mechanisms, are used and the effects on the burning behavior as well as mechanical and thermal properties are evaluated. Ammonium polyphosphate (APP), used with a filler degree of 20 wt.% or higher, functions as the best performing flame retardant in this study

    A scaling law for distinct electrocaloric cooling performance in low-dimensional organic, relaxor and anti-ferroelectrics

    Get PDF
    Electrocaloric (EC) materials show promise in eco-friendly solid-state refrigeration and integrable on-chip thermal management. While direct measurement of EC thin-films still remains challenging, a generic theoretical framework for quantifying the cooling properties of rich EC materials including normal-, relaxor-, organic- and anti-ferroelectrics is imperative for exploiting new flexible and room-temperature cooling alternatives. Here, we present a versatile theory that combines Master equation with Maxwell relations and analytically relates the macroscopic cooling responses in EC materials with the intrinsic diffuseness of phase transitions and correlation characteristics. Under increased electric fields, both EC entropy and adiabatic temperature changes increase quadratically initially, followed by further linear growth and eventual gradual saturation. The upper bound of entropy change (∆Smax) is limited by distinct correlation volumes (V cr ) and transition diffuseness. The linearity between V cr and the transition diffuseness is emphasized, while ∆Smax = 300 kJ/(K.m3) is obtained for Pb0.8Ba0.2ZrO3. The ∆Smax in antiferroelectric Pb0.95Zr0.05TiO3, Pb0.8Ba0.2ZrO3 and polymeric ferroelectrics scales proportionally with V cr −2.2, owing to the one-dimensional structural constraint on lattice-scale depolarization dynamics; whereas ∆Smax in relaxor and normal ferroelectrics scales as ∆Smax ~ V cr −0.37, which tallies with a dipolar interaction exponent of 2/3 in EC materials and the well-proven fractional dimensionality of 2.5 for ferroelectric domain walls

    The BarYon CYCLE Project (ByCycle): Identifying and Localizing MgII Metal Absorbers with Machine Learning

    Full text link
    The upcoming ByCycle project on the VISTA/4MOST multi-object spectrograph will offer new prospects of using a massive sample of ∼1\sim 1 million high spectral resolution (RR = 20,000) background quasars to map the circumgalactic metal content of foreground galaxies (observed at RR = 4000 - 7000), as traced by metal absorption. Such large surveys require specialized analysis methodologies. In the absence of early data, we instead produce synthetic 4MOST high-resolution fibre quasar spectra. To do so, we use the TNG50 cosmological magnetohydrodynamical simulation, combining photo-ionization post-processing and ray tracing, to capture MgII (λ2796\lambda2796, λ2803\lambda2803) absorbers. We then use this sample to train a Convolutional Neural Network (CNN) which searches for, and estimates the redshift of, MgII absorbers within these spectra. For a test sample of quasar spectra with uniformly distributed properties (λMgII,2796\lambda_{\rm{MgII,2796}}, EWMgII,2796rest=0.05−5.15\rm{EW}_{\rm{MgII,2796}}^{\rm{rest}} = 0.05 - 5.15 \AA, SNR=3−50\rm{SNR} = 3 - 50), the algorithm has a robust classification accuracy of 98.6 per cent and a mean wavelength accuracy of 6.9 \AA. For high signal-to-noise spectra (SNR>20\rm{SNR > 20}), the algorithm robustly detects and localizes MgII absorbers down to equivalent widths of EWMgII,2796rest=0.05\rm{EW}_{\rm{MgII,2796}}^{\rm{rest}} = 0.05 \AA. For the lowest SNR spectra (SNR=3\rm{SNR=3}), the CNN reliably recovers and localizes EWMgII,2796rest_{\rm{MgII,2796}}^{\rm{rest}} ≥\geq 0.75 \AA\, absorbers. This is more than sufficient for subsequent Voigt profile fitting to characterize the detected MgII absorbers. We make the code publicly available through GitHub. Our work provides a proof-of-concept for future analyses of quasar spectra datasets numbering in the millions, soon to be delivered by the next generation of surveys.Comment: 13 pages, 9 figures, 1 table. Accepted for publication in MNRA

    A novel filter wheel for multi-channel switching and polarization rotation

    Get PDF
    This study proposes an innovative filter wheel for the multi-channel switching of polarization state. The proposed device enables switching between two orthogonal linear polarization states or two orthogonal circular polarization states to achieve either linear dichroism (LD) or circular dichroism (CD). The filter wheel enables channel switching and orientation rotation with high repeatability. This paper describes in detail the methods used in the alignment of multiple polarizers and quarter-waveplates. In addition, the extinction ratio and retardation, which can be used as indications of polarimetric performance, are measured to a high degree of precision. The apparatus was applied for 6-channel polarization state switching in which three channels were used for multi-spectral broadband polarimetric applications across a range of 400–1600 nm. The remaining three channels were used for multi-wavelength precision polarimetric applications at wavelengths of 457, 532, and 632 nm in the visible range. When installed in a microspectrophotometer, the proposed apparatus can be used in multi-spectral broadband polarimetric spectroscopy as well as multi-wavelength polarimetric imaging applications to achieve LD and CD effects at the micro scale

    Improving identification & management of familial hypercholesterolaemia in primary care: pre- and post-intervention study

    Get PDF
    Background and Aims: Familial hypercholesterolaemia (FH) is a major cause of premature heart disease but remains unrecognised in most patients. This study investigated if a systematic primary care-based approach to identify and manage possible FH improves recommended best clinical practice. Methods: Pre- and post-intervention study in six UK general practices (population 45,033) which invited patients with total cholesterol >7.5 mmol/L to be assessed for possible FH. Compliance with national guideline recommendations to identify and manage possible FH (repeat cholesterol; assess family history of heart disease; identify secondary causes and clinical features; reduce total & LDL-cholesterol; statin prescribing; lifestyle advice) was assessed by calculating the absolute difference in measures of care pre- and six months post-intervention. Results: The intervention improved best clinical practice in 118 patients consenting to assessment (of 831 eligible patients): repeat cholesterol test (+75.4%, 95% CI 66.9-82.3); family history of heart disease assessed (+35.6%, 95% CI 27.0-44.2); diagnosis of secondary causes (+7.7%, 95% CI 4.1-13.9), examining clinical features (+6.0%, 95% CI 2.9-11.7). For 32 patients diagnosed with possible FH using Simon-Broome criteria, statin prescribing significantly improved (18.8%, 95% CI 8.9-35.3) with non-significant mean reductions in cholesterol post-intervention (total: -0.16 mmol/L, 95% CI -0.78-0.46; LDL: -0.12 mmol/L, 95% CI -0.81-0.57). Conclusions: Within six months, this simple primary care intervention improved both identification and management of patients with possible FH, in line with national evidence-based guidelines. Replicating and sustaining this approach across the country could lead to substantial improvement in health outcomes for these individuals with very high cardiovascular risk
    • …
    corecore