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This study aims to evaluate the potential of percutaneous patent foramen ovale (PFO) closure to improve the headache in patients with migraine and PFO, and discuss the difference between the randomized controlled trials (RCTs) and the single-center studies. Patients of migraine with a large shunt of PFO, who experienced ≥2 headache attacks per month and failed ≥2 categories of standardized medication, underwent PFO closure in First Affiliated Hospital of Xi'an Jiao Tong University. The clinical outcomes, including frequency and duration of headache attacks, Headache Impact Test (HIT-6) score, and Visual Analogue Scale (VAS) score, were evaluated at 3, 6, and 12 months of follow-up after the PFO closure. The different efficacies of the clinical outcomes between patients with and without aura as well as different grades of PFO were also evaluated, respectively. 134 patients with migraine (39 male and 95 female) with PFO were enrolled, whose average age was 39.21±11.37 years. After PFO closure, there was a significant reduction in frequency and duration of headache attacks, HIT-6 score, and VAS score at 3, 6, and 12 months’ follow-up (p50% in 44 (32.84%) patients at 3 months’ follow-up and increased to 48 (35.82%) at 12 months’ follow-up. 31.03% patients remained residual shunt after 6 months of closure with varying improvements of headache. This study confirmed that PFO closure can effectively reduce frequency and duration of migraine and improve quality of life, but the definitive indications and long-term effect still need further research.

Recent development on 3D flash memories largely promotes the wide application of Solid-State Drives (SSDs) by providing larger capacity from vertically-stacked layers. However, there exist speed variations across different layers because of manufacturing process variations or physical designs, which induces new challenges to fully explore the advantages of existing SSDs, e.g. the parallel structure. This paper investigates the effect of speed variation on the parallel performance of SSDs. To balance chips’ workloads, traditional method selects chips in a round-robin way. As chip queue time can be estimated by some main factors, the chip also can be chosen in a greedy way. However, because of the layer speed variation, queue time estimation model should be modified. This paper first establishes a new queue time estimation model with the awareness of the flash layer information. Then the model is used to estimate the chip queue time and to direct write requests into the chip with the least queue time. The key idea is to largely reduce queue time of each write, thus reducing the average SSD response time. Finally, this new request redirection method is evaluated on SSDsim with real world workloads. Experimental results show that our model can estimate the queue time more accurately and our new request redirection method can improve 8.3% of write queue time on average under the situation of 4 times speed variation among 16 layers.

Wireless sensor networks as the base support for the Internet of things have been a large number of popularity and application. Such as intelligent agriculture, we have to use the sensor network to obtain the growing environment data of crops and others. However, the difficulty of power supply of wireless nodes has seriously hindered the application and development of Internet of things. In order to solve this problem, people use low-power sleep scheduling and other energy-saving methods on the nodes. Although these methods can prolong the working time of nodes, they will eventually become invalid because of the exhaustion of energy. The use of solar energy, wind energy, and wireless signals in the environment to obtain energy is another way to solve the energy problem of nodes. However, these methods are affected by weather, environment, and other factors, and they are unstable. Thus, the discontinuity work of the node is caused. In recent years, the development of wireless power transfer (WPT) has brought another solution to this problem. In this paper, a three-layer framework is proposed for mobile station data collection in rechargeable wireless sensor networks to keep the node running forever, named TLFW which includes the sensor layer, cluster head layer, and mobile station layer. And the framework can minimize the total energy consumption of the system. The simulation results show that the scheme can reduce the energy consumption of the entire system, compared with a Mobile Station in a Rechargeable Sensor Network (MSiRSN).

3-D triple-level cell (3-D TLC) NAND flash has high storage density and capacity, but degrading data reliability due to high raw bit error rates induced by a certain number of program/erase cycles. To guarantee data reliability, low-density parity-check (LDPC) codes are selected as the error correction codes in modern flash memories because of strong error correction capability. However, directly adopting LDPC codes induces high decoding latency due to iterative updating of log-likelihood ratio (LLR) information in the decoding process. Increasing LLR information accuracy can greatly improve decoding performance. In this paper, we propose EMAL: using error modes aware LDPC codes for further enhancing the decoding performance of 3-D TLC NAND flash. We first obtain 3-D TLC error modes based on an FPGA testing platform, and then exploit the error modes to optimize LLR information and enable the decoding to converge at a high speed. The simulation results show that the decoding performance is significantly improved, resulting in reduced bit error rates and decoding latency.

The recent development of 3D flash memories has promoted the widespread application of SSDs in modern storage systems by providing large storage capacity and low cost. Garbage collection (GC) as a time-consuming but necessary operation in flash memories largely affects the performance. In this paper, we perform a comprehensive experimental study on how garbage collection impacts the performance of flash-based SSDs, in the view of performance cliff that closely relates to Quality of Service (QoS). According to the study results using real-world workloads, we first observe that GC occasionally causes response time spikes, which we call the performance cliff problem. Then, we find that 3D SSDs exacerbate the situation by inducing a much higher number of page migrations during GC. To relieve the performance cliff problem, we propose PreGC to assist normal GC. The key idea is to distribute the page migrations into the period before normal GC, thus leading to a reduction in page migrations during the GC period. Comprehensive experiments with real-world workloads have been performed on the SSDsim simulator. Experimental results show that PreGC can efficiently relieve the performance cliff by reducing the tail latency from the 90th to 99.99th percentiles while inducing a little extra write amplification.

By storing multibit per cell, multilevel cell (MLC) NAND flash memory achieves high storage capacity, but sacrificing data reliability. Error correction codes, such as Bose–Chaudhuri–Hocquenghem (BCH) codes, are widely used to ensure data reliability. However, high raw bit error rates induced by interference noises make BCH codes become insufficient to guarantee data reliability. Low-density parity-check (LDPC) codes are considered as the replacement due to the stronger error correction capability. Nevertheless, directly exploiting LDPC codes introduces a concern about decoding latency because of their iterative decoding in the soft decision process. To develop effective LDPC decoding algorithms, it is necessary to have a more profound understanding on flash failure patterns. This paper first observes the pair-bit errors (PBEs) characteristic of MLC NAND flash memory on a real field-programmable gate array testing platform, then proposes a PBE-aware LDPC (PAL) decoding scheme-based upon this observation, in which PBE provides the promotion information for LDPC decoding to reduce decoding latency. Simulation results show that the decoding latency can be reduced by up to 54%, compared with the conventional LDPC codes.

Read-ahead schemes of page cache have been widely used to improve read performance of Linux systems. As Android system inherits the Linux kernel, traditional read-ahead schemes are directly applied in mobile devices. However, read request sizes and page cache sizes in mobile devices are much smaller than other platforms, which may decrease read-ahead efficiency and hurt user experience. The read-ahead efficiency is defined as hit pages / all pre-fetched pages in a sequential read. To study the efficiency of traditional read-ahead in mobile devices, this paper first observes that many pre-fetched pages are unused in page cache, which causes high page cache eviction ratio with high extra access latency. Then, this paper analyzes the factors that closely relate to the access latency. It is found that there exists a trade-off between read-ahead size and access latency. A size-tuning scheme is then proposed to explore this trade-off. Experimental results on real mobile devices have shown that the proposed scheme can reduce the number of pre-fetched pages and improve the efficiency of read-ahead without decreasing the page cache hit ratio.

Numerous published studies have investigated the relationship between the CD14-260C>T (rs2569190) polymorphism and the risk of myocardial infarction (MI). However, the results are still conflicting and inconclusive. Potentially eligible published articles were searched in four databases including PubMed, Web of Science, EMBASE and Chinese Biomedical Database (CBM). The odds ratio (OR) with its 95% confidence interval (CI) was used to estimate the strength of the associations. Thirteen papers including 17 case-control studies were included, reporting a total of 6,443 MI patients and 6,315 controls. A significant increase in overall MI susceptibility was identified in the homozygote model. In the subgroup analysis, with respect to the type of MI, a significantly increasing acute MI susceptibility was found in the homozygote model. In the subgroup analysis for ethnicity, a significant increased susceptibility was found in Asian populations in allele, homozygote, recessive and dominant models. However, no significant association was found among Caucasian populations. In conclusion, there may be a moderate association between the CD14-260C>T polymorphism and acute MI susceptibility. This association may be different between ethnicities with the CD14-260C>T polymorphism being a risk factor for myocardial infarction in Asian populations.

Higher mortality in asthmatics has been shown previously. However, evidence on different asthma phenotypes on long-term mortality risk is limited. The aim was to evaluate the impact of asthma phenotypes on mortality in general population. Data from the National Health and Nutrition Examination Survey from 2001–2002 to 2013–2014 linked mortality files through December 31, 2015, were used (N = 37,015). Cox proportional hazards regression was used to estimate the risk of all-cause and cause-specific mortality adjusting for sociodemographic characteristics, smoking, body mass index, and chronic conditions. During the mean follow-up time of 7.5 years, 4326 participants died from a variety of causes. Current asthma, but not former asthma was associated with increased all-cause mortality (current asthma: HR = 1.37; 95% CI 1.20–1.58; Former asthma: HR = 0.93; 95% CI 0.73–1.18); as well as mortality from cardiovascular disease (HRCurrent = 1.41; 95% CI 1.08–1.85) and chronic lower respiratory diseases (HRCurrent = 3.17; 95% CI 1.96–5.14). In addition, we found that the HR for cardiovascular disease (CVD) mortality was slightly greater in people with childhood-onset asthma than those with adult-onset asthma. The HR for chronic lower respiratory diseases (CLRD) mortality was greater in people with adult-onset asthma than those with childhood-onset asthma. However, the differences were not statistically significant. Our study suggested that current asthma but not former asthma was associated with increased all-cause, CLRD and CVD mortality. Future well-designed studies with larger sample are required to demonstrate the association and clarify the potential mechanisms involved.

Similar to other digital assets, deep neural network (DNN) models could suffer from piracy threat initiated by insider and/or outsider adversaries due to their inherent commercial value. DNN watermarking is a promising technique to mitigate this threat to intellectual property. This work focuses on black-box DNN watermarking, with which an owner can only verify his ownership by issuing special trigger queries to a remote suspicious model. However, informed attackers, who are aware of the watermark and somehow obtain the triggers, could forge fake triggers to claim their ownerships since the poor robustness of triggers and the lack of correlation between the model and the owner identity. This consideration calls for new watermarking methods that can achieve better trade-off for addressing the discrepancy. In this paper, we exploit frequency domain image watermarking to generate triggers and build our DNN watermarking algorithm accordingly. Since watermarking in the frequency domain is high concealment and robust to signal processing operation, the proposed algorithm is superior to existing schemes in resisting fraudulent claim attack. Besides, extensive experimental results on 3 datasets and 8 neural networks demonstrate that the proposed DNN watermarking algorithm achieves similar performance on functionality metrics and better performance on security metrics when compared with existing algorithms.

Background There is growing evidence that pseudogenes may serve as prognostic biomarkers in several cancers. The present study was designed to develop and validate an accurate and robust pseudogene pairs-based signature for the prognosis of hepatocellular carcinoma (HCC). Methods RNA-sequencing data from 374 HCC patients with clinical follow-up information were obtained from the Cancer Genome Atlas (TCGA) database and used in this study. Survival-related pseudogene pairs were identified, and a signature model was constructed by Cox regression analysis (univariate and least absolute shrinkage and selection operator). All individuals were classified into high- and low-risk groups based on the optimal cutoff. Subgroups analysis of the novel signature was conducted and validated in an independent cohort. Pearson correlation analyses were carried out between the included pseudogenes and the protein-coding genes based on their expression levels. Enrichment analysis was performed to predict the possible role of the pseudogenes identified in the signature. Results A 19-pseudogene pair signature, which included 21 pseudogenes, was established. Patients in high-risk group demonstrated an increased the risk of adverse prognosis in the TCGA cohort and the external cohort (all P P Conclusion The novel proposed and validated pseudogene pair-based signature may serve as a valuable independent prognostic predictor for predicting survival of patients with HCC.

Objective: To identify feature autophagy-related genes (ARGs) in patients with acute myocardial infarction (AMI) and further investigate their value in the diagnosis of AMI. Methods: Gene microarray expression data of AMI peripheral blood samples were downloaded from the GSE66360 dataset. The data were randomly classified into a discovery cohort (21 AMI patients and 22 healthy controls) and a validation cohort (28 AMI patients and 28 healthy controls). Differentially expressed ARGs between patients with AMI and healthy controls in the discovery cohort were identified using a statistical software package. Feature ARGs were screened based on support vector machine-recursive feature elimination (SVM-RFE), and an SVM classifier was constructed. Receiver operating characteristic (ROC) analysis was used to investigate the predictive value of the classifier, which was further verified in an independent external cohort. Results: A total of seven genes were identified based on SVM-RFE. The SVM classifier had an excellent discrimination ability in both the discovery cohort (area under the curve [AUC] = 0.968) and the validation cohort (AUC = 0.992), which was further confirmed in the GSE48060 dataset (AUC = 0.963). Furthermore, the SVM classifier showed outstanding discrimination between AMI patients with and without recurrent events in the independent external cohort (AUC = 0.992). The identified genes are mainly involved in the cellular response to autophagy, macroautophagy, apoptosis, and the FoxO signaling pathway. Conclusion: Our study identified feature ARGs and indicated their potential roles in AMI diagnosis to improve our understanding of the molecular mechanism underlying the occurrence of AMI.

The loess formation sampling method on the Chinese Loess Plateau generally involves the acquisition of samples from the basset section and the drilling core. Constraints imposed by the precision of the drilling machine operation make it difficult to determine the orientation of the samples due to the rotation of the core.Although researchers have proposed solutions for reconstructing the north direction of the samples by adopting the viscous remanent magnetization (VRM) orientation, it remains uncertain whether this approach can be adopted in studies that use the magnetic fabric to trace the palaeomonsoonal direction, and the degree to which this approach will change the magnetic fabric results.Based on the achievements of other researchers, we adopted the VRM orientation of the basset section samples oriented in the field. By determining how the VRM orientation changes the magnetic fabric of loess over different demagnetization temperature ranges, we can draw the preliminary conclusion that there is no significant difference between the magnetic fabric information of the loess obtained at 100–150°C VRM orientation and that obtained from the field orientation (the statistical bin size is 22.5°, significance level α = 0.05). This indicates that the VRM orientation approach is feasible for studying non-oriented drilling core samples to determine the prevailing surface paleowind direction with appropriate precision.

We present a new 10Be record spanning the Matuyama-Brunhes (M-B) reversal from the Heqing paleolake basin in southern China. It provides a robust proxy for past geomagnetic variations that can be compared with paleomagnetic records. The M-B transition is identified as a pronounced maximum of authigenic 10Be/9Be ratio between 768.6 and 778.5 ka, that is consistent with all other available 10Be-proxy records from marine, ice and loess archives. However, it is offset by approximately 0–60 cm depth from the magnetic signature of the polarity transition recorded in the same sediments. We attribute this offset to the lock-in effect of the remanence acquisition process, which is similar to the phenomenon that exists in marine sediments. We suggest that after eliminating the climatic-hydrological signal, the Heqing sediments may be used as an archive for atmospheric 10Be production rate changes. The combination of magnetic remanence measurements and the cosmogenic 10Be allows for a more precise geochronology of geomagnetic polarity reversals.

Present advanced precise race detection techniques leverage strict causal relation to locate data races, leading to false negatives and missing many hidden races. In this paper, we present a novel race detection technique, called DigHR, which can detect more hidden races than existing precise techniques. DigHR is based on a weak causal relation, called afterward-confirm (AC) relation, which relaxes restrictions of existing causal relations and is proved to be sound. To represent AC relations between events, we propose a new data structure, called water-flow graph, which enable DigHR to analyze AC relations and detect hidden races at run-time. We have implemented DigHR in C/C++ and evaluated the effectiveness of DigHR by detecting races from real-world benchmarks and applications. The experimental results show that DigHR can precisely detect 21% more races than previous techniques, including FastTrack and CP.

Address space layout randomization (ASLR) is now widely adopted in modern operating systems to thwart code reuse attacks. However, an adversary can still bypass fine-grained ASLR by exploiting memory corruption vulnerabilities and performing memory disclosure attacks. Although Execute-no-Read schemes have been proven to be an efficient solution against read-based memory disclosures, existing solutions need modifications to kernel or hypervisor. Besides, the defense of execution-based memory disclosures has been ignored. In this paper, we propose BoundShield, a self-protection scheme that provides comprehensive protection against memory disclosure attacks, especially against those based on executing arbitrary code by leveraging Intel Memory Protection Extension . BoundShield protects code memory by defending not only read-based memory disclosure attacks but also execution-based memory disclosure attacks. On one hand, read-based memory disclosures can be eliminated by hiding all code sections and code pointers in a secret region separated from the user address space. On the other hand, BoundShield prevents return addresses from being corrupted and ensures that all function pointers point to the legitimate entries whenever they are dereferenced, which significantly reduces the attack surface for execution-based memory disclosures. We have implemented a prototype of BoundShield based on a set of modifications to compiler toolchain and the standard C library. Our evaluation results show that the BoundShield can provide strong defenses against memory disclosure attacks while incurring a small performance overhead.

3D-multi-level cell (MLC) NAND flash memory adopts 3D stack technology and stores two bits per cell, leading to improved storage capacities, but sacrificing data reliability. Low-density parity-check (LDPC) codes showing strong error correction capability benefit from their soft decision decoding, which is widely exploited to guarantee data reliability. Nevertheless, adopting LDPC codes can introduce a concern about read performance, because their iterative soft-decision decoding requires Log-Likelihood Ratio (LLR) information, called soft decision information, by applying multi-sensing voltages. This process of obtaining LLR information leads to high sensing and transferring latencies, lowering down 3D-MLC read performance. In particular, when raw bit error rates (RBER) are much higher due to the long retention periods and program/erase (P/E) cycles, this problem becomes more serious. In this paper, we propose a RBER-aware multi-sensing scheme for reducing sensing and transferring latencies, and thus improving read performance. This proposed scheme exploits the variations of RBER in flash pages with the increase of retention time and P/E cycles to dynamically apply sensing voltages. Simulation results show that this scheme significantly decreases the number of required sensing voltages while maintaining LDPC error correction capability, enhancing 3D-MLC read performance.

Concurrent techniques have been widely adopted in software systems, and data race has become a great threat to stability and security of concurrent systems. Previous precise race detection techniques either may miss many races, or are only suitable for some specific programs, such as the programs executed in a virtual machine rather than in actual hardware. To solves these problems, this paper introduces a dynamic predictive race detector, called LayDetect, which detects predictable races in C/C++ programs. LayDetect applies an innovative layering technique, which can detect more races than other detectors, such as FastTrack. We have implemented and evaluated LayDetect with well-known benchmarks and real-world applications. LayDetect has detected 3.7 M races at run-time which is more than that of FastTrack by two orders of magnitude, while the average slowdown (3.0 $$\times $$ ) and space overhead (34.1 MB) of LayDetect are similar to that of FastTrack.

A potential association between type 1 diabetes mellitus and subsequent epilepsy emerged in recent studies. This study aimed to evaluate the possible relationship between type 1 diabetes mellitus and epilepsy using meta-analysis. Pubmed, ISI Web of Knowledge, Embase and Cochrane Library were searched for potential studies of the association between type 1 diabetes mellitus and epilepsy from inception to February 1, 2017. Two investigators independently screened studies for inclusion and extracted related data; discrepancies were solved by consensus. Random effects model of Hazard Ratio (HR) was used to estimate the strength of association. We identified 13 papers from potentially relevant articles of which 3 cohort studies met the inclusion criteria. Random effects meta-analysis showed that type 1 diabetes mellitus was associated with an increased risk of epilepsy with HR = 3.29 (95% CI: 2.61-4.14; I2 = 0, p = 0.689). Similar results were observed in type 1 diabetes mellitus patents younger than 18-years-old with HR = 2.96 (95% CI: 2.28-3.84; I2 = 0, p = 0.571). Meta-analysis of 2 studies that adjusted for potential confounders yielded an increased risk of epilepsy with HR = 2.89 (95% CI: 2.26-3.70; I2 = 0, p = 0.831). The meta-analysis indicates that type 1 diabetes mellitus is associated with a statistically significant increased risk for epilepsy compared to those without type 1 diabetes mellitus.

In order to satisfy the increased concern on SSD performance, this paper studied GC performance in the view of performance cliff and tail latency. At first, our preliminary experiments figure out that increased page migrations is the root cause of performance cliff. Then, combined with the existing works aiming at GC performance in 2D SSDs, including the partial GC and aggressive GC, a novel GC-assisting method PreGC is proposed to relieve GC-induced performance cliff. The key idea of PreGC is that a part of pages within victim blocks can be pre-migrated ahead of the time nearby GC invoking and when system is idle. Thus, normal page migrations induced by GC can be reduced and response time peaks would be lowered down. Experimental results show that PreGC can efficiently relieve the performance cliff by reducing migrated page numbers in normal GC as well as the tail latency while inducing negligible write amplification.

Solid state drives (SSDs) widely used in cyber-physical systems have to use block cleaning operations to reclaim storage space because of the out-of-place update characteristics. As these operations often take high time costs and do harm to flash lifetime because of write amplification, SSD system performance has been largely decreased. Garbage collection and wear leveling, as two typical block cleaning techniques, are invoked without enough communication between each other, which may induce one block repeatedly cleaned within a short period, leading to worse performance and lifetime of SSDs. This paper proposes an unified block cleaning method called UniBC by considering the two invoking conditions unitedly to reduce the cost of overall block cleaning. In details, UniBC makes garbage collection able to consider the wear degree of victim blocks by utilizing constrained victim block selection techniques and wear leveling be aware of the utilization degree of victim blocks. By exploiting UniBC, repetitive block cleaning operations can be avoided and overall system performance can be improved. Experimental results show that UniBC can improve 10% block cleaning performance on average.

Purpose. To compare the sensitivity and specificity of modified and traditional methods of contrast echocardiography of the right portion of the heart in patients with a suspicion of patent foramen ovale (PFO). Methods. The study population consisted of 506 patients with high clinical suspicion of PFO. The traditional Valsalva maneuver consists of expiration against a closed glottis after a full inspiration. A modified Valsalva maneuver was performed with a handmade pressure monitoring device, which measured pressure during performance of the Valsalva maneuver. Modified and traditional methods of contrast echocardiography were performed among all patients. Contrast transesophageal echocardiography (TEE) was regarded as the gold standard. Results. A total of 279 patients with PFO were confirmed by TEE. 259 cases (sensitivity: 92.83%) were detected by a modified method of contrast echocardiography of the right portion of the heart, while 234 cases were detected using the traditional method (sensitivity: 83.87%). The sensitivity of modified contrast echocardiography of the right portion of the heart was significantly higher than that of the traditional method (92.83% vs. 83.87%, P=0.001). However, there was no significant difference in the specificity of the two methods for the diagnosis of PFO (97.35% vs. 96.03%, P=0.431). Additionally, the results of semiquantitative evaluation of PFO using modified method failed to show a more positive rate than shown by the traditional method (Z=−1.782, P=0.075). Conclusions. Modified contrast echocardiography of the right portion of the heart yielded a higher sensitivity than the traditional method, which contributed to the diagnosis of cardiac PFO. The research was a part of a register study (https://register.clinicaltrials.gov/ ClinicalTrials ID: NCT02777359).

Buffer overflow (BoF) is one of the most dangerous security vulnerabilities. A BoF can be induced by functions, such as the memcpy family, or loops with pointer or array operations. Static detection of BoF is a well-defined method and often performed before system deployment. However, most of previous static techniques either detect the BoFs induced by functions or analyze simple loops that induce BoFs, such as the single loop with a single loop variable. In order to clearly understand the impact of loops on BoF, we perform an empirical study on real-world BoFs detected in the past three years, including 211 BoFs from 60 open-source systems, and find that about a third of these BoFs are induced by loops. Motivated by this observation, we propose a novel static detection technique, DBloop, to localize BoFs induced by loops. The key of DBloop is to get the extremum length of data-movement on the buffer by analyzing target loops and then check whether the buffer overruns using constraint solving. We have implemented DBloop with CIL, and evaluated it on real-world programs detection by comparing with a commercial tool, Checkmarx, and an open-source tool, Splint. DBloop successfully localizes 57 BoFs induced by loops, while Checkmarx and Splint only detect 4 and 3, respectively. Moreover, DBloop has detected 4 new BoFs that have not been reported before.

Copyback is an advanced command contributing to accelerating data migration in garbage collection (GC). Unfortunately, detecting copyback feasibility (whether copyback can be carried out with assurable reliability) against data corruption in the traditional copyback-based GC causes an expensive performance penalty. This paper first explores copyback error characteristics on real NAND flash chips, then proposes a fast garbage collection scheme called FastGC. It utilizes copyback error characteristics to efficiently detect copyback feasibility of data instead of transferring out all valid data for detecting. Experiment results in the SSDsim show the proposed FastGC greatly promotes write response time and read response time by up to 44.2% and 66.3% respectively, compared to the traditional copyback-based GC.

Studies of cosmogenic 10Be in Chinese loess began about twenty-five years ago and since then a number of research groups worldwide have contributed to a firm understanding of the production, transport, deposition and storage of 10Be in loess. The essential characteristics that make 10Be a useful isotopic tracer in loess, include: (1) dominant atmospheric production directly linked to the intensity of the Earth’s magnetic field; (2) climate-dependent deposition; and (3) subsequent immobility, so that as 10Be accumulates in a loess profile its stratigraphic integrity is preserved. This fact, combined with very high deposition rates in loess on the Chinese Loess Plateau, makes 10Be an especially valuable continental archive of paleoclimate and paleomagnetism, complementing marine and ice-core records. Here we provide in particular the most recent progress of 10Be tracer studies in Chinese loess, including the determination of the correct age of the Brunhes–Matuyama polarity reversal at 780 ± 3 ka B.P., in accord with marine and ice records, and quantitative reconstruction of 130-ka paleoprecipitation using 10Be from Chinese loess profiles.

The storage capacity of NAND Flash has increased by scaling down to smaller cell size and using multi-level storage technology, but data reliability is degraded by severer retention errors. To ensure data reliability, error correction codes (ECC) are adopted, such as BCH and low-density parity check (LDPC) codes. However, BCH codes are insufficient when raw bit error rates (RBER) caused by retention errors are high. As a result, BCH codes are inevitably replaced with LDPC codes with stronger error correction capability. Traditional LDPC codes are used to independently correct bit errors in the LSB and MSB pages. Unfortunately, decoding latency in such two pages is significantly unbalanced, MSB pages take much higher latency due to higher RBER, leading to suboptimal flash read performance. This paper proposes a cooperative error correction scheme, called CooECC, to reduce LDPC decoding latency of the MSB page in NAND Flash. By exploiting data error characteristics introduced by retention errors, CooECC integrates the decoding result of the LSB page into the initial information of LDPC decoding for the MSB page, making it more accurate. This in turn enables decoding to converge at a higher rate. Simulation results show that for LDPC schemes with information lengths of 2KB and 4KB, the decoding latency can be reduced by up to 87% and 84%, respectively, when RBER is as high as 8.0 × 10^-3.

With the development of bit density and technology scaling, the process variation (PV) has become much severe on NAND flash memory. As PV presents reliability among flash blocks, which causes read performance variation to read data on different blocks. This paper proposes to improve read performance of LDPC based flash memory by exploiting the reliability characteristics of PV. First, a block grouping approach is proposed to classify the flash blocks based on their reliability. Then, a read data placement scheme is proposed, which is designed to place read-hot data on flash blocks with high reliability and move read-cold data to blocks with low reliability. Experiment results show that, with negligible overhead, the proposed scheme is able to significantly improve the read performance.

This paper proposes to improve read performance of LDPC based flash memory by exploiting process variation (PV). The work includes three parts. First, a block grouping approach is proposed to classify the flash blocks based on their reliability. Second, based on the grouping approach, a read data placement scheme is proposed, which is designed to place read-hot data on flash blocks with high reliability. However, simply placing read-hot data to high reliable blocks conflicts with recent PV-aware wear leveling schemes. In the third part of the work, a grouping partition scheme is proposed to limit the number of high reliable blocks for read-hot data. In this case, read performance can be well improved with little impact on the lifetime improvement.

Numerous reports have been done to seek the relationship between sleep apnea hypopnea syndrome (SAHS) and the risk of atrial fibrillation (AF). However, definite conclusion has not yet been fully established. We examined whether SAHS increases AF incidence in common population and summarized all existing studies in a meta-analysis. We summarized the current studies by searching related database for potential papers of the association between SAHS and the risk of AF. Studies that reported original data or relative risks (RRs) with 95% confidence intervals (CIs) for the associations were included. Sensitivity analyses were performed by omitting each study iteratively and publication bias was detected by Begg’s tests. Eight eligible studies met the inclusion criteria. Fixed effects meta-analysis showed that SAHS increased AF risk in the common population (RR = 1.70, 95% CI: 1.53–1.89, P=0.002, I2=69.2%). There was a significant association between mild SAHS and the risk of AF (RR = 1.52, 95% CI: 1.28–1.79, P=0.01, I2=78.4%), moderate SAHS (RR = 1.88, 95% CI: 1.55–2.27, P=0.017, I2=75.6%), and severe SAHS (RR = 2.16, 95% CI: 1.78–2.62, P<0.001, I2=91.0%). The results suggest that sleep apnea hypopnea syndrome could increase the risk of AF, and the higher the severity of SAHS, the higher risk of atrial fibrillation.

With the technology scaling of solid state drives (SSDs), data reliability has to be ensured by advanced Low-Density Parity-Check (LDPC) codes. As LDPC reads often take high latency, read performance involved in traditional garbage collection, called external GC, is largely decreased, which affects system performance. GC can choose not to correct data with LD-PC codes but just copy valid pages into registers of NAND flash, which we call internal GC. Although this method avoids long latency in LDPC reads, the data integrity is sacrificed because of error aggregation in valid pages. To balance performance and reliability, this paper proposes a new garbage collection method, named as LDPC-aware Garbage Collection (LaGC), to selectively choose blocks with high error rates to perform external GC. These blocks are often close to uncorrectable error rates, which take a small portion during a long flash life period. Thus, most of blocks perform internal GC and keep advantage of low read latency. Experimental results show that LaGC can reduce 78% of read latency in external GC and achieve about 2% system performance improvement.

3D NAND flash memory has been well developed due to its high density and decreasing cost compared with planar flash. However, one issue for 3D NAND flash, which has not been well solved, is its worse read disturb. The worse read disturb of 3D NAND flash stems from its much more word lines in a block. In this case, it receives much more read operations, leading to increased read disturb. Previous work proposed to relax the read disturb on planar flash through reducing the pass-through voltage, V pass , on the unread word lines. However, this is not viable for 3D NAND flash with the increased number of word lines in a block. In this work, a new read disturb reduction scheme is proposed for 3D NAND flash. First, a read error model is presented, which demonstrates that selective V pass reduction is a viable approach. Then, a read-hotness aware V pass reduction scheme is proposed to improve performance without violating the reliability requirement. Simulation shows that the proposed scheme achieves encouraging performance improvement.

Flash Friendly File System (F2FS) is getting popular among mobile devices. However, lack of empirical and comprehensive analysis for characteristics of F2FS prohibits better application of F2FS. In this paper, we present a set of comprehensive experimental studies on mobile devices and show several counterintuitive observations on F2FS, including imprecise hot/cold data separation, unexpected trigger condition of background GC, impact of fragmentation on read performance and impact of readahead by fragments and available space. Based on these observations, we further provide several pilot solutions to improve the performance of these mobile devices. The objective is to inspire researchers and users to pay attention to F2FS characteristics, and further optimize its performance.

The factors controlling climate in China's western interior are numerous and quite complex. These vary on seasonal to multi-millennial time scales as a result of changing dominance of influence from the Westerlies and the Asian and Indian Monsoon systems. These in turn respond to additional factors such as the dynamics of the Walker and Hadley circulation in the Pacific and Indian Ocean basins, the strength of the Siberian and Northwest Pacific Highs, and on long timescales to changes in the distribution of solar insolation resulting from orbital forcing. Here, we use the Empirical Orthogonal Function (EOF) analysis to investigate the spatiotemporal patterns of climate in China's western interior during the last 15 ka as revealed from a suite of 17 lacustrine carbonate δ18O records. Based on similarities to the EOF analysis of the modern data, we interpret the first two leading eigenmodes of the paleodata sets as P and T, respectively. Other climatic proxy data from this region appear to agree well with this interpretation. Our analysis reveals a discrete change in the spatial EOF patterns occurring at circa 7.5–6 ka BP with respect to the patterns observed prior to this. These patterns suggest that the arid NW region of the study area became significantly wetter following this juncture, but that the Asian Monsoon influenced (SE) region of the study area along the eastern flank of the Tibetan Plateau became drier. A more complex pattern of change is revealed by the second rank EOF, interpreted as temperature. This shows a discrete change at ∼7.5–6 ka BP from cooler to hotter temperatures on the central Tibetan Plateau, but slightly cooler temperatures in the lowland Monsoon affected area (SE) after 6 ka BP. We interpret both these sets of changes to result from more persistent high pressure over the Tibetan Plateau during Boreal summer, with a resultant enhancement of moisture transport by the westerlies and diminished monsoonal flow following ∼6 ka BP.

Cosmogenic 10Be is a promising precipitation index, because its fallout flux in sediments is mainly controlled by wet precipitation after its production in the atmosphere. Here we report on a new study for reconstructing precipitation during the last 130 ka using 10Be measurements from Chinese loess, with multivariable linear regression to remove the geomagnetic field modulation and dust flux dilution effects from the loess 10Be record. The broad similarity between our result and speleothem δ18O indicates that the new precipitation record is robust. It also records an interesting increase in precipitation that occurred during Marine Isotope Stage 3 (MIS 3), exhibiting a similar rainfall amount with that of MIS 5, suggesting that MIS 3 is a special period with strengthened summer Monsoon intensity. By comparison with a stacked marine isotope record and a summer insolation record, our precipitation data clearly show a close correspondence with Northern Hemisphere summer (June, July, and August) solar insolation changes on orbital timescales. During MIS 3, our record follows the insolation differential between 30°N and 30°S, suggesting that rising rainfall changes during MIS 3 are a response to the interhemispheric summer insolation differential forcing.

The collapse of some pre-historical and historical cultures, including Chinese dynasties were presumably linked to widespread droughts, on the basis of synchronicities of societal crises and proxy-based climate events. Here, we present a comparison of ancient inscriptions in Dayu Cave from Qinling Mountains, central China, which described accurate times and detailed impacts of seven drought events during the period of 1520–1920 CE, with high-resolution speleothem records from the same cave. The comparable results provide unique and robust tests on relationships among speleothem δ18O changes, drought events and societal unrest. With direct historical evidences, our results suggest that droughts and even modest events interrupting otherwise wet intervals can cause serious social crises. Modeling results of speleothem δ18O series suggest that future precipitation in central China may be below the average of the past 500 years. As Qinling Mountain is the main recharge area of two large water transfer projects and habitats of many endangered species, it is imperative to explore an adaptive strategy for the decline in precipitation and/or drought events.

This paper proposes a cascading algorithm (CSR) based on compressed sensing, which aims to reduce intensive computations in super-resolution imaging of fluorescence microscopy. Performance of existing algorithms such as CVX and L1H drop sharply when applied to obtain finer images with high density molecules. CSR fully exploits the extreme sparsity property of molecules in the compressed sensing model and progressively restricts solution space stage by stage. We perform a comprehensive study of existing algorithms and the proposed algorithm under different resolutions and molecules’ densities. Simulation and experimental results confirm the performance advantage of CSR when applied to recover dense molecules.

The purpose of this study was to compare the effectiveness and safety of a single vs dual occluders in the treatment of multiple atrial septal defects (ASDs).We retrospectively reviewed the records of patients with multiple ASDs treated with single or dual Amplatzer septal occluders from January 2010 to March 2013. Data extracted from the medical records included patient demographic information, ASD sizes, distance between the defects, preprocedure and postprocedure echocardiographic parameters, and treatment-related complications. Treatment success was defined as the occluder stably fixed without shunting, and no effects to other heart structures.Sixty-four patients were included. There were no significant differences between the two groups with respect to age, weight, gender, larger ASD diameter, smaller ASD diameter, and echocardiographic parameters before treatment. Successful closure was achieved in all patients in the single-occluder group regardless of whether the distance between defects was ≥7 mm or7 mm, and in all patients in the dual-occluder group. Residual shunting after surgery and residual leakage after 1-year follow-up were significantly more common in the dual-occluder group compared with the single-occluder group (residual shunting: 31% vs. 8%, respectively; P=.02 and residual leakage: 19% vs. 2%, respectively; P=.04). No procedure-related complications occurred in either group.Single and dual occluders are both safe and effective for the repair of multiple ASDs; however, the risk of residual shunt is greater with dual occluders.

To observe the effect of oversized occluder on endothelialization post percutaneous closure of experimental atrial septal defect (ASD) in dogs.ASD was established with the help of transthoracic echocardiography in 18 dogs. ASD size was (6.0 ± 0.2) mm. Dogs were randomly divided into normal size group (implanted with 8 mm occlude, n = 9) and oversized group (implanted with 12 mm occluder, n = 9). Dogs were randomly killed at 3, 6 and 14 months after percutaneous closure. The endothelialization process on device surface was observed by scanning electron microscope.Four animals died around 1 month post procedure. Microscopic sections from normal group showed nearly complete endothelialization at 3 months after device implantation and complete endothelialization at 6 and 14 months after device implantation. While microscopic sections showed lack of endothelialization at 3 months post implantation, nearly endothelialization at 6 months, and complete endothelialization at 14 months after device implantation in oversized group.Incomplete endothelialization of occluder surface is observed at 6 months after implantation of an oversized ASD occluder device in this model.