I/O Schedulers for Proportionality and Stability on Flash-Based SSDs in Multi-Tenant Environments

The use of flash based Solid State Drives (SSDs) has expanded rapidly into the cloud computing environment. In cloud computing, ensuring the service level objective (SLO) of each server is the major criterion in designing a system. In particular, eliminating performance interference among virtual machines (VMs) on shared storage is a key challenge. However, studies on SSD performance to guarantee SLO in such environments are limited. In this paper, we present analysis of I/O behavior for a shared SSD as storage in terms of proportionality and stability. We show that performance SLOs of SSD based storage systems being shared by VMs or tasks are not satisfactory. We present and analyze the reasons behind the unexpected behavior through examining the components of SSDs such as channels, DRAM buffer, and Native Command Queuing (NCQ). We introduce two novel SSD-aware host level I/O schedulers on Linux, called A & x002B;CFQ and H & x002B;BFQ, based on our analysis and findings. Through experiments on Linux, we analyze I/O proportionality and stability in multi-tenant environments. In addition, through experiments using real workloads, we analyze the performance interference between workloads on a shared SSD. We then show that the proposed I/O schedulers almost eliminate the interference effect seen in CFQ and BFQ, while still providing I/O proportionality and stability for various I/O weighted scenarios

Effects of Body Mass Index on Ankle Joint Muscle Function and Dynamic Proprioceptive Control

PURPOSE Increased body mass index (BMI) increases ankle instability and adversely affects human movement. This study aims to compare and analyze the muscle function and proprioception of the ankle joint based on Body Mass Index (BMI) to determine potential differences. METHODS Twenty-eight healthy male and female college students were categorized into overweight (≥ BMI 23) and normal (< BMI 23) groups. Measurements included BMI, isokinetic strength of dorsiflexion, plantarflexion, eversion, inversion, ankle joint range of motion, and ankle joint proprioception. RESULTS In dorsiflexion, right 30°/sec (p=.035), left 30°/sec (p=.009) and right 120°/sec (p=.011); in plantarflexion, left 30°/sec (p<.001), right 120°/sec (p=.007) and left 120°/sec (p=.006) in ankle inversion, left 30°/sec (p=.001), right 120°/sec (p=.021) and left 120°/sec (p=.007), left 30°/sec (p=.014), 120°/sec (p=.001) in ankle inversion-eversion ratio, right (p=.003) and left (p=.003) in ankle joint range of motion, right (p<.001) and left (p=.022) in total proprioception, and left (p<.001) in left-right proprioception were significantly different between the normal and overweight groups. CONCLUSIONS It was found that the overweight group had lower muscle strength, joint range of motion, and proprioceptive control function of the ankle joint than the normal group according to BMI. Therefore, exercise programs should be provided to strengthen the periarticular muscles involved in ankle movement, such as the tibialis anterior, soleus, and peroneus longus, and to control dynamic proprioception to prevent ankle injuries and function of the ankle joint according to BMI

Hybrid compression of hyperspectral images based on PCA with pre-encoding discriminant information

It has been shown that image compression based on principal component analysis (PCA) provides good compression efficiency for hyperspectral images. However, PCA might fail to capture all the discriminant information of hyperspectral images, since features that are important for classification tasks may not be high in signal energy. To deal with this problem, we propose a hybrid compression method for hyperspectral images with pre-encoding discriminant information. A feature extraction method is first applied to the original images, producing a set of feature vectors that are used to generate feature images and then residual images by subtracting the feature-reconstructed images from the original ones. Both feature images and residual images are compressed and transmitted. Experiments on data from the Airborne Visible/Infrared Imaging Spectrometer sensor indicate that the proposed method provides better compression efficiency with improved classification accuracy than conventional compression methods

STAT3 inhibitor mitigates cerebral amyloid angiopathy and parenchymal amyloid plaques while improving cognitive functions and brain networks

Previous reports indicate a potential role for signal transducer and activator of transcription 3 (STAT3) in amyloid-β (Aβ) processing and neuritic plaque pathogenesis. In the present study, the impact of STAT3 inhibition on cognition, cerebrovascular function, amyloid pathology, oxidative stress, and neuroinflammation was studied using in vitro and in vivo models of Alzheimer\u27s disease (AD)-related pathology. For in vitro experiments, human brain vascular smooth muscle cells (HBVSMC) and human brain microvascular endothelial cells (HBMEC) were used, and these cultured cells were exposed to Aβ peptides followed by measurement of activated forms of STAT3 expression and reactive oxygen species (ROS) generation. Further, 6 months old 5XFAD/APOE4 (5XE4) mice and age-matched negative littermates were used for in vivo experiments. These mice were treated with STAT3 specific inhibitor, LLL-12 for 2 months followed by neurobehavioral and histopathological assessment. In vitro experiments showed exposure of cerebrovascular cells to Aβ peptides upregulated activated forms of STAT3 and produced STAT3-mediated vascular oxidative stress. 5XE4 mice treated with the STAT3-specific inhibitor (LLL-12) improved cognitive functions and functional connectivity and augmented cerebral blood flow. These functional improvements were associated with a reduction in neuritic plaques, cerebral amyloid angiopathy (CAA), oxidative stress, and neuroinflammation. Reduction in amyloid precursor protein (APP) processing and attenuation of oxidative modification of lipoprotein receptor related protein-1 (LRP-1) were identified as potential underlying mechanisms. These results demonstrate the broad impact of STAT3 on cognitive functions, parenchymal and vascular amyloid pathology and highlight the therapeutic potential of STAT3 specific inhibition for treatment of AD and CAA

High performance polymer light-emitting diodes with N-type metal oxide/conjugated polyelectrolyte hybrid charge transport layers

We present an interfacial engineering strategy employing n-type-metal-oxide/conjugated-polyelectrolyte (CPE) hybrid charge-transport layers for highly efficient polymer light-emitting diodes (PLEDs). The hybrid metal-oxide/CPE layer facilitates electron-injection, while blocking hole-transport, and thereby maximizes electron-hole recombination within the emitting layer. A series of metal-oxide/CPE combinations were tested in inverted PLEDs (FTO/metal-oxide/CPF8BT/MoO3/Au). Specifically, HfO2/CPE double layer achieved an electroluminescence (EL) efficiency of up to 25.8 cd/A (@ 6.4 V, one of the highest values reported for fluorescent PLEDs).open11

IO Optimization Techniques for Disk-based Graph Engines

Department of Computer Science and Engineeringope