Quasiparticle self‐consistent many‐body perturbation theory (MBPT) methods that update both eigenvalues and eigenvectors can calculate the excited‐state properties of molecular systems without ...depending on the choice of starting points. However, those methods are computationally intensive even on modern multi‐core central processing units (CPUs) and thus typically limited to small systems. Many‐core accelerators such as graphics processing units (GPUs) may be able to boost the performance of those methods without losing accuracy, making starting‐point‐independent MBPT methods applicable to large systems. Here, we GPU accelerate MOLGW, a Gaussian‐based MBPT code for molecules, with open accelerators (OpenACC) and achieve speedups of up to 9.7×$$ 9.7\times $$ over 32 open multi‐processing (OpenMP) CPU threads.
Quasiparticle self‐consistent many‐body perturbation theory (MBPT) methods implemented in MOLGW, a central processing unit (CPU) code for MBPT calculations of electronic excitations in molecules, are accelerated on graphics processing units (GPUs), which enables the application of predictive MBPT methods without depending on the choice of starting points to large systems.
Abstract
In this series of papers, we present new methods of frequency- and time-dependent instrumental polarization calibration for very long baseline interferometry (VLBI). In most existing ...calibration tools and pipelines, it has been assumed that instrumental polarization is constant over frequency within the instrument bandwidth and over time. The assumption is not always true and may prevent an accurate calibration, which can result in degradation of the quality of linear polarization images. In this paper, we present a method of frequency-dependent instrumental polarization calibration that is implemented in GPCAL, a recently developed polarization calibration pipeline. The method is tested using simulated data sets generated from real Very Long Baseline Array (VLBA) data. We present the results of applying the method to real VLBA data sets observed at 15 and 43 GHz. We were able to eliminate significant variability in cross-hand visibilities over frequency that is caused by frequency-dependent instrumental polarization. As a result of the calibration, linear polarization images were slightly to modestly improved as compared to those obtained without frequency-dependent instrumental polarization calibration. We discuss the reason for the minor impact of frequency-dependent instrumental polarization calibration on existing VLBA data sets and prospects for applying the method to future VLBI data sets, which are expected to provide very large bandwidths.
Abstract
We present a new method of time-dependent instrumental polarization calibration for very long baseline interferometry (VLBI). This method has been implemented in the recently developed ...polarization calibration pipeline GPCAL. Instrumental polarization, also known as polarimetric leakage, is a direction-dependent effect, and it is not constant across the beam of a telescope. Antenna pointing model accuracy is usually dependent on time, resulting in off-axis polarimetric leakages that can vary with time. The method is designed to correct for the off-axis leakages with large amplitudes that can severely degrade linear polarization images. Using synthetic data generated based on real Very Long Baseline Array (VLBA) data observed at 43 GHz, we evaluate the performance of the method. It was able to reproduce the off-axis leakages assumed in the synthetic data, particularly those with large amplitudes. The method has been applied to two sets of real VLBA data, and the derived off-axis leakages show very similar trends over time for pairs of nearby sources. Furthermore, the amplitudes of the off-axis leakages are strongly correlated with the antenna gain correction factors. The results demonstrate that the method is capable of correcting for the off-axis leakages present in VLBI data. By calibrating time-dependent instrumental polarization, the rms noise levels of the updated linear polarization images have been significantly reduced. The method is expected to substantially enhance the quality of linear polarization images obtained from existing and future VLBI observations.
We present the Generalized Polarization CALibration pipeline (GPCAL), an automated pipeline for instrumental polarization calibration of very long baseline interferometry (VLBI) data. The pipeline is ...designed to achieve a high calibration accuracy by means of fitting the instrumental polarization model, including the second-order terms, to data from multiple calibrator sources simultaneously. It also allows for using more accurate linear polarization models of calibrators for D-term estimation compared to the conventional way that assumes similar linear polarization and total intensity structures. This assumption has been widely used in the existing packages for instrumental polarization calibration but could be a source of significant uncertainties when there is no suitable calibrator satisfying the assumption. We demonstrate the capabilities of GPCAL by using simulated data, archival Very Long Baseline Array (VLBA) data of many active galactic nucleus (AGN) jets at 15 and 43 GHz, and our Korean VLBI Network (KVN) observations of many AGN jets at 86, 95, 130, and 142 GHz. The pipeline could reproduce the complex linear polarization structures of several sources shown in the previous studies using the same VLBA data. In addition, GPCAL reveals a complex linear polarization structure in the flat-spectrum radio quasar 3C 273 from the KVN data at all four frequencies. These results demonstrate that GPCAL can achieve a high calibration accuracy for various VLBI arrays.
Precipitation related to atmospheric rivers (ARs) is critical in shaping climate and extreme hydrologic events in the mid‐latitude coastal regions, making it a recent topic of intense research. This ...study has analysed the AR climatology, AR‐precipitation characteristics and their regional variations in East Asia (EA) for 1979–2015 using an AR inventory based on vertically‐integrated water‐vapour transport and AR geometry. The AR frequency over EA varies seasonally with highest (lowest) frequency in summer (winter). The AR frequency peaks in the coastal regions of the mid‐latitude western North Pacific (WNP), then decreases rapidly away from the region towards higher/lower latitudes and inlands. ARs are related to 30–60% of the annual precipitation in EA with maximum in summer; secondary peaks occur in spring in eastern China, Korea and southern Japan, and in winter for the southern China coast. Calculating the AR precipitation on days of partial AR occurrences from daily precipitation data is a key source of uncertainties in the AR‐precipitation fraction in this study. The AR days are substantially more related to heavy precipitation than non‐AR days for all seasons and regions. Seasonal cycle of AR frequency over EA and the WNP follows the northward march of the main rainband from spring to mid‐summer, but is decoupled from it from late summer to winter as the North Pacific storm track migrates into the Eastern North Pacific. The annual cycle of AR frequency and AR precipitation varies regionally; Japan and southern China adjacent to WNP show high (low) frequency of weak‐ (heavy‐) precipitating ARs in early spring (late fall) with highly frequent heavy‐precipitating ARs in summer while the mid‐latitude coastal regions, eastern China and Korea, show low frequency of heavy‐precipitating ARs in early fall with highly frequent heavy‐precipitating ARs in mid‐summer.
Precipitation related to atmospheric rivers (ARs) like shown in the image is important in shaping the regional hydroclimate in East Asia (EA). This study reveals that ARs contribute 30–60% of the annual precipitation in EA with maximum in summer and minimum in winter. The seasonal evolution of AR activities follows the northward march of the EA monsoon rainband from spring to early summer, then is decoupled from it in fall and winter.
Old-age poverty in Korea remains exceptionally high among OECD countries despite a significant expansion in pension expenditure. This article presents an institutional explanation for such a puzzle. ...Using ‘targeting within universalism’ as the analytic framework, this study examines the institutional effects of pension models on old-age poverty in Korea. Firstly, comparative analysis finds that universal provision of pensions negatively affects old-age poverty independent of the expenditure size, identifying Korean pensions as the least universal among OECD countries. Secondly, institutional analysis of the Korean pension system explains why the expenditure growth left a large share of the elderly with no or a partial pension. Finally, microsimulation analysis examines alternative assistance pension models for their potential to alter poverty outcomes. Strikingly, universal models alleviate old-age poverty more cost-effectively than the extant targeting model, questioning the efficiency-based justification for low-income targeting. In particular, the universal floor model appears to be the most effective, allowing greater benefits to the poorer without a means test. Even for assistance benefits, universal models may better remedy poverty under such conditions as low take-up among the needy, prevalence of low-income incidence, and pro-rich distribution of extant social transfers.
To reconcile the inconsistencies and complexities in the relationship between team diversity and performance, our meta‐analysis takes a more nuanced approach to the relationship between team ...deep‐level diversity and team performance. We examine the type of deep‐level diversity (personality, values, culture), task complexity, and executive team status as moderators of the relationship between team deep‐level diversity and positive emergent states, positive team processes, and team conflict. In addition, we examine the mediating role of positive team emergent states, positive team processes, and team conflict in explaining how team deep‐level diversity relates to team performance. We test our hypotheses with a meta‐analytic database of 94 papers reporting 280 effect sizes based on 24,425 teams. Findings show that team deep‐level diversity is associated with fewer positive emergent states and positive team processes and more team conflict. There is an indirect relationship between team deep‐level diversity and team performance through each of the mediators: positive emergent states, positive team processes, and team conflict. Implications for theory and practice are discussed.
Label-free biosensing methods that rely on the use of localized surface plasmon resonance (LSPR) have attracted great attention as a result of their simplicity, high sensitivity, and relatively low ...cost. However, in-situ analysis of real samples using these techniques has remained challenging because colloidal nanoparticles (NPs) can be unstable at certain levels of pH and salt concentration. Even in the case of a chip-type LSPR sensor that can resolve the instability problem by employing NPs immobilized on the substrate, loading of a sample to sensor chip with exact volume control can be difficult for unskilled users. Herein, we report an optical-fiber-based LSPR aptasensor that can avoid these problems and serve as a portable and simple system for sensitive detection of a small mycotoxin, ochratoxin A (OTA), in real samples. The optical fiber coated with aptamer-modified gold nanorods (GNRs) is simply dipped into a solution containing OTA and subjected to LSPR analysis. Quantitative analysis of OTA is performed by measuring the spectral red shift of the LSPR peak of GNRs. Under optimized conditions, the LSPR peak shift displays a linear response (R2 = 0.9887) to OTA in the concentration range from 10pM to 100nM, with a limit of detection of 12.0pM (3S). The developed sensor shows a high selectivity for OTA over other mycotoxins such as zearalenone (ZEN) and ochratoxin B (OTB), and shows an accurate detection capability for OTA in real grape juice samples.
•Simple and in situ measurement of OTA was possible by dipping a sensing probe into solution samples.•Wide dynamic range from 10pM to 100nM was achieved.•Limit of detection (LOD) for OTA was reached to 12.0pM (3S).•OTA in grape juice could be successfully analyzed with good recoveries.
Aim
To evaluate the long term root coverage outcomes of coronally advanced flap plus a connective tissue graft with (CAF + CTG) or without an epithelial collar (CAF + ECTG), and evaluate the adjacent ...treated sites included in the flap.
Methods
Seventeen of the original 20 subjects included in the randomized clinical trial were available at 12 years (43 sites). Mean root coverage (mRC), keratinized tissue width (KTW), gingival thickness (GT) on the grafted and adjacent sites were evaluated and compared with baseline and 6 months.
Result
There was a reduction in the mRC at all sites: 16.52% in the CAF + CTG (p > .05), 19.42% in the CAF + ECTG (p < .05) and 34.12% in the CAF‐alone (adjacent treated sites) group (p < .05). No significant differences were observed within the groups for changes in KTW, GT and clinical attachment level (CAL) (p > .05). Keratinized tissue width at baseline and at 6 months was found to be predictors for the stability of the gingival margin in the long term.
Conclusions
CAF + CTG and CAF + ECTG were found equally efficacious in maintaining the levels of the gingival margin with a small amount of relapse over the period of 12 years while CAF‐alone sites showed a greater gingival recession (GR) reoccurrence.
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