A highly selective electrochemical assay based on the Sakaguchi reaction for the detection of protein arginine methylation state

Protein arginine methylation is a common form of post-translational modification that plays an important role in many bioprocesses. However, research advances in this field have been severely hampered by the lack of a quick and sensitive method for detecting the arginine methylation state of a protein. In this work we propose a direct and sensitive electrochemical method for identifying the arginine methylation state. This novel assay combines an electrochemical technique with the Sakaguchi reaction, which is highly selective towards the arginine methylation state. We show that the presence of a methyl group on the arginine residue of a protein prevents the Sakaguchi reaction, while the unmethylated arginine residue selectively reacts with 8-hydroxyquinoline; the electrical signal of the reaction product is used for electrochemical detection. From this, a highly selective and simple electrochemical sensor has been developed based on (1) the high selectivity of the Sakaguchi reaction towards the arginine methylation state, and (2) the sensitive electrochemical signal generated by the linked 8-hydroxyquinoline. The assay described in this work thus provides a convenient tool for detection of protein arginine methylation, which may facilitate studies of the biological functions of protein arginine methylases and demethylases

Infrared permittivity of the biaxial van der Waals semiconductor α\alpha-MoO3_3 from near- and far-field correlative studies

The biaxial van der Waals semiconductor $\alpha$-phase molybdenum trioxide ($\alpha$-MoO$_3$) has recently received significant attention due to its ability to support highly anisotropic phonon polaritons (PhPs) -infrared (IR) light coupled to lattice vibrations in polar materials-, offering an unprecedented platform for controlling the flow of energy at the nanoscale. However, to fully exploit the extraordinary IR response of this material, an accurate dielectric function is required. Here, we report the accurate IR dielectric function of $\alpha$-MoO$_3$ by modelling far-field, polarized IR reflectance spectra acquired on a single thick flake of this material. Unique to our work, the far-field model is refined by contrasting the experimental dispersion and damping of PhPs, revealed by polariton interferometry using scattering-type scanning near-field optical microscopy (s-SNOM) on thin flakes of $\alpha$-MoO$_3$, with analytical and transfer-matrix calculations, as well as full-wave simulations. Through these correlative efforts, exceptional quantitative agreement is attained to both far- and near-field properties for multiple flakes, thus providing strong verification of the accuracy of our model, while offering a novel approach to extracting dielectric functions of nanomaterials, usually too small or inhomogeneous for establishing accurate models only from standard far-field methods. In addition, by employing density functional theory (DFT), we provide insights into the various vibrational states dictating our dielectric function model and the intriguing optical properties of $\alpha$-MoO$_3$

Variation of cataract surgery costs in four different graded providers of China

<p>Abstract</p> <p>Background</p> <p>China has the largest population of cataract patients in the world. However, the cataract surgery rate per million remains low in China. We carried out a survey on costs of cataract surgery from four different graded providers in China and analyzed differences in cost among these clinics.</p> <p>Methods</p> <p>1,189 patients were recruited for the study in four eye clinics, located in two provinces, Guangdong province in southern China and Hubei province in central China. The average cost of each cataract surgery episode was calculated including cost of intraocular lens, cost of drugs and facility cost. We also collected information on reimbursement and disposable annual income of local residents.</p> <p>Results</p> <p>Mean total cost per cataract intervention of four different providers varied considerably, ranging from US$1,293 in Union Hospital to US$ 536 in Jingshan County Hospital. In all providers, except for Jingshan County Hospital, the cost exceeded annual disposable income of local rural residents. As to the proportion of patients with reimbursement, the figure for Union Hospital was only 36%, while for other three clinics it was more than 60%. There was a significant difference between mean reimbursement ratios, with the highest ratio in Zhongshan Ophthalmic Center being 71%.</p> <p>Conclusions</p> <p>Significant differences in costs of cataract surgery were found among the 4 different graded providers. A part of the cost was borne by patients. Proportion of patients with reimbursement and mean reimbursement ratios were higher in economically developed regions than in economically developing regions. Much more financial support should be directed into the rural New Cooperative Medical Scheme to raise the reimbursement ratio in rural China.</p

Direct observation of spin polarization in epitaxial Fe3O4(001)/MgO thin films grown by magnetron sputtering

We obtained epitaxial single-crystal Fe3O4(001)/MgO(001) thin films by magnetron sputtering. The high quality of the grown Fe3O4 films was confirmed by reflection high-energy electron diffraction and x-ray photoelectron spectroscopy. Atomic magnetic properties of Fe3O4(001)/MgO(001) were investigated using vibrating sample magnetometry and x-ray magnetic circular dichroism. The values of saturation magnetization and magnetic moment are 407 ± 5 emu/cm3 (3.26 ± 0.04 μ B / (f. u.)) and 3.31 ± 0.15 μ B / (f. u.), respectively, in the Fe3O4 film as thin as 5 nm, which are close to the bulk values. The spin polarization was directly measured using spin-resolved photoemission spectroscopy. The measured spin polarization has a maximum value of -42% ± 3%, which is comparable to the theoretical value for the (2 × 2)R45° reconstructed Fe3O4(001) surface. Furthermore, the film thickness-dependent measurements indicate that the anti-phase boundaries significantly decrease the spin polarization rather than the lattice mismatch. Our results demonstrate that epitaxial Fe3O4(001)/MgO thin films grown by magnetron sputtering have desired magnetic properties, facilitating the potential application of Fe3O4-based spintronic devices

The Double Burdens of Mental Health Among AIDS Patients With Fully Successful Immune Restoration: A Cross-Sectional Study of Anxiety and Depression in China

Background: Anxiety and depression continue to be significant comorbidities for people with HIV infection. We investigated the prevalence of and factors associated with anxiety and depression among adult HIV-infected patients across China.Methods: In this cross-sectional study, we described clinical and psychosocial variables related to depression and anxiety in 4103 HIV-infected persons. Doctors assessed anxiety and depression by asking patients whether they had experienced anxiety or depression in the prior month. Patients also self-administered the Hospital Anxiety and Depression (HAD) scale; those with score ≥8 on HAD-A/D were considered to be at high risk of anxiety or depression.Results: Associations between socio-demographic, psychosocial, and ART-related clinical factors and risk of depression or anxiety were investigated using multivariable logistic regression. Among patients assessed between 9/2014 and 11/2015, 27.4% had symptoms of anxiety, 32.9% had symptoms of depression, and 19.0% had both. Recentness of HIV diagnoses (P = 0.046) was associated with elevated odds of anxiety. Older age (P = 0.004), higher educational attainment (P &lt; 0.001), employment (P = 0.001), support from family / friends (P &lt; 0.001), and sleep disturbance (P &lt; 0.001), and number of ART regimen switches (P = 0.046) were associated with risk of depression, while neither sex nor transmission route showed any associations. There were no significant associations with HIV-specific clinical factors including current CD4+ T cell count and current viral load.Conclusions: Prevalence of symptoms of anxiety and depression is high in this cohort of treatment-experienced HIV patients. Psychological and social-demographic factors, rather than HIV disease status, were associated with risk of depression and anxiety. This finding highlights the need to deliver interventions to address the mental health issues affecting HIV-infected persons with fully successful immune restoration across China

Safe vs. Fair: A formidable trade-off in tackling climate change

Global warming requires a response characterized by forward-looking management of atmospheric carbon and respect for ethical principles. Both safety and fairness must be pursued, and there are severe trade-offs as these are intertwined by the limited headroom for additional atmospheric CO2 emissions. This paper provides a simple numerical mapping at the aggregated level of developed vs. developing countries in which safety and fairness are formulated in terms of cumulative emissions and cumulative per capita emissions respectively. It becomes evident that safety and fairness cannot be achieved simultaneously for strict definitions of both. The paper further posits potential global trading in future cumulative emissions budgets in a world where financial transactions compensate for physical emissions: the safe vs. fair tradeoff is less severe but remains formidable. Finally, we explore very large deployment of engineered carbon sinks and show that roughly 1,000 Gt CO2 of cumulative negative emissions over the century are required to have a significant effect, a remarkable scale of deployment. We also identify the unexplored issue of how such sinks might be treated in sub-global carbon accounting

Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals &lt;1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

PMap : unlocking the performance genes of HPC applications

Performance modeling, the science of understanding and predicting application performance, is important but challenging. High Performance Computing (HPC) with large- scale applications and aggressive technologies, such as dynamic computational grids, hybrid computing platforms, and innovative storage systems, further complicates the task. This dissertation proposed and proved the hypothesis that a small number of performance primitives can be extracted from HPC applications and leveraged for fast application performance modeling and prediction even on large-scale dynamic systems. PMap : a set of methods and tools to extract, measure, and analyze performance primitives in HPC applications are proposed, implemented, and verified under these challenging environments. Two production computational grids, Teragrid and Geon, were monitored with periodically running benchmarks for about half a year. Their performance fluctuated in the 50% range. However, simple benchmarks that serve as performance primitives can be used to predict application performance with a relative error as low as 9%. To map program constructs to the best matched hardware components in hybrid computing platforms, an automatic idioms (performance primitives) recognition method was proposed and implemented based on the open source compiler Open64. With the NAS Parallel Benchmark (NPB) as a case study, the prototype system is about 90% accurate compared with idiom classfication by a human expert. The performance of the idiom benchmarks with their corresponding in- stances in the NPB codes on two different platforms were compared with different methods. The approximation accuracy is up to 97%. With the HPC data challenge and emerging storage technologies, a flash-based supercomputer DASH was designed, built, and tuned. A large parameter space was swept by fast and reliable measurements developed to investigate varying design options, and the results showed that performance can be improved by as much as 9x with appropriate existing technologies developed here. Finally, the PMaC framework was extended to model and predict application performance on flash storage systems. Results showed that the total I/O time can be predicted with reasonable error of 15%. The end result of this body of work is that the performance of applications on supercomputers can be understood by mapping their performance genetic

Cash holdings, the internal capital market, and capital allocation efficiency in listed companies

AbstractThe rise in firm-level cash asset ratios has become a prominent trend in countries around the world which may further influence the capital allocation efficiency. This study analysed the inefficient effect of cash holdings on the capital allocation by combining the internal capital market theory with principal–agent theory and asymmetric information theory. The theoretical hypotheses were tested using linear panel regression models based on financial data from Chinese listed enterprises. We found that corporations holding more cash assets had lower capital allocation efficiency than those with fewer cash assets, which is consistent with agency theory and asymmetric information theory. Internal capital markets exacerbated this adverse effect. Additional testing was conducted to examine the heterogeneity of this effect between different types of ownership and strategy; the findings showed that an increase in cash holdings had a greater marginal impact on overinvestment among privately owned enterprises and underinvestment among state-owned enterprises. Internal capital market operation alleviated the problem of overinvestment but exacerbated the problem of underinvestment in privately owned enterprises, whereas it increased overinvestment in state-owned enterprises. The results suggested that different types of enterprises should deal with the inefficient effect of cash assets based on the causes of inefficient investment