B+-tree Index Optimization by Exploiting Internal Parallelism of Flash-based Solid State Drives

Previous research addressed the potential problems of the hard-disk oriented design of DBMSs of flashSSDs. In this paper, we focus on exploiting potential benefits of flashSSDs. First, we examine the internal parallelism issues of flashSSDs by conducting benchmarks to various flashSSDs. Then, we suggest algorithm-design principles in order to best benefit from the internal parallelism. We present a new I/O request concept, called psync I/O that can exploit the internal parallelism of flashSSDs in a single process. Based on these ideas, we introduce B+-tree optimization methods in order to utilize internal parallelism. By integrating the results of these methods, we present a B+-tree variant, PIO B-tree. We confirmed that each optimization method substantially enhances the index performance. Consequently, PIO B-tree enhanced B+-tree's insert performance by a factor of up to 16.3, while improving point-search performance by a factor of 1.2. The range search of PIO B-tree was up to 5 times faster than that of the B+-tree. Moreover, PIO B-tree outperformed other flash-aware indexes in various synthetic workloads. We also confirmed that PIO B-tree outperforms B+-tree in index traces collected inside the Postgresql DBMS with TPC-C benchmark.Comment: VLDB201

Infrared Camera-Based Non-contact Measurement of Brain Activity From Pupillary Rhythms

Pupillary responses are associated with affective processing, cognitive function, perception, memory, attention, and other brain activities involving neural pathways. The present study aimed to develop a noncontact system to measure brain activity based on pupillary rhythms using an infra-red web camera. Electroencephalogram (EEG) signals and pupil imaging of 70 undergraduate volunteers (35 female, 35 male) were measured in response to sound stimuli designed to evoke arousal, relaxation, happiness, sadness, or neutral responses. This study successfully developed a real-time system that could detect an EEG spectral index (relative power: low beta in FP1; mid beta in FP1; SMR in FP1; beta in F3; high beta in F8; gamma P4; mu in C4) from pupillary rhythms using the synchronization phenomenon in harmonic frequency (1/100 f) between the pupil and brain oscillations. This method was effective in measuring and evaluating brain activity using a simple, low-cost, noncontact system, and may be an alternative to previous methods used to evaluate brain activity

Toward a Better Understanding of Loss Functions for Collaborative Filtering

Collaborative filtering (CF) is a pivotal technique in modern recommender systems. The learning process of CF models typically consists of three components: interaction encoder, loss function, and negative sampling. Although many existing studies have proposed various CF models to design sophisticated interaction encoders, recent work shows that simply reformulating the loss functions can achieve significant performance gains. This paper delves into analyzing the relationship among existing loss functions. Our mathematical analysis reveals that the previous loss functions can be interpreted as alignment and uniformity functions: (i) the alignment matches user and item representations, and (ii) the uniformity disperses user and item distributions. Inspired by this analysis, we propose a novel loss function that improves the design of alignment and uniformity considering the unique patterns of datasets called Margin-aware Alignment and Weighted Uniformity (MAWU). The key novelty of MAWU is two-fold: (i) margin-aware alignment (MA) mitigates user/item-specific popularity biases, and (ii) weighted uniformity (WU) adjusts the significance between user and item uniformities to reflect the inherent characteristics of datasets. Extensive experimental results show that MF and LightGCN equipped with MAWU are comparable or superior to state-of-the-art CF models with various loss functions on three public datasets.Comment: Accepted by CIKM 202

Integrated Analysis Method for Stability Analysis and Maintenance of Cut-Slope in Urban

In the process of constructing roads for the development of the city, cut-slopes are made by excavating mountains. However, these cut-slopes are degraded in strength by time-deterioration phenomenon, and progressive slope failure is caused. This study developed an integrated analysis method for stability analysis and maintenance of cut-slopes in urban. The slope stability analysis was performed using the finite element model, and the progressive slope failure by time-dependent deterioration was quantified by using the strength parameters of soil applying the strength reduction factor (SRF). The displacements until the slope failure by slope stability analysis were quantified by cumulative displacement curve, velocity curve, and inverse velocity curve and, applied to the slope maintenance method. The inverse-velocity curve applied to the prediction of the time of slope failure was regressed to the 1st linear equation in the brittle material and the 3rd polynomial equation in the ductile material. This is consistent with the proposed formula of Fukuzono and also shows similar behavior to the failure case in literature. In the future, integrated analysis method should be improved through additional research. And it should be applied to cut-slope to prevent disasters

The local translation of KNa in dendritic projections of auditory neurons and the roles of KNa in the transition from hidden to overt hearing loss

Local and privileged expression of dendritic proteins allows segregation of distinct functions in a single neuron but may represent one of the underlying mechanisms for early and insidious presentation of sensory neuropathy. Tangible characteristics of early hearing loss (HL) are defined in correlation with nascent hidden hearing loss (HHL) in humans and animal models. Despite the plethora of causes of HL, only two prevailing mechanisms for HHL have been identified, and in both cases, common structural deficits are implicated in inner hair cell synapses, and demyelination of the auditory nerve (AN). We uncovered that N

Feasibility, Accuracy and Performance of Contact Block Reduction method for multi-band simulations of ballistic quantum transport

Numerical utilities of the Contact Block Reduction (CBR) method in evaluating the retarded Green's function, are discussed for 3-D multi-band open systems that are represented by the atomic tight-binding (TB) and continuum k\cdotp (KP) band model. It is shown that the methodology to approximate solutions of open systems which has been already reported for the single-band effective mass model, cannot be directly used for atomic TB systems, since the use of a set of zincblende crystal grids makes the inter-coupling matrix be non-invertible. We derive and test an alternative with which the CBR method can be still practical in solving TB systems. This multi-band CBR method is validated by a proof of principles on small systems, and also shown to work excellent with the KP approach. Further detailed analysis on the accuracy, speed, and scalability on high performance computing clusters, is performed with respect to the reference results obtained by the state-of- the-art Recursive Green's Function and Wavefunction algorithm. This work shows that the CBR method could be particularly useful in calculating resonant tunneling features, but show a limited practicality in simulating field effect transistors (FETs) when the system is described with the atomic TB model. Coupled to the KP model, however, the utility of the CBR method can be extended to simulations of nanowire FETs.Comment: 10 Pages, 9 Figure

Single-Cell RNA-seq Reveals Profound Alterations in Mechanosensitive Dorsal Root Ganglion Neurons with Vitamin E Deficiency.

Ninety percent of Americans consume less than the estimated average requirements of dietary vitamin E (vitE). Severe vitE deficiency due to genetic mutations in the tocopherol transfer protein (TTPA) in humans results in ataxia with vitE deficiency (AVED), with proprioceptive deficits and somatosensory degeneration arising from dorsal root ganglia neurons (DRGNs). Single-cell RNA-sequencing of DRGNs was performed in Ttpa-/- mice, an established model of AVED. In stark contrast to expected changes in proprioceptive neurons, Ttpa-/- DRGNs showed marked upregulation of voltage-gated Ca2+ and K+ channels in mechanosensitive, tyrosine-hydroxylase positive (TH+) DRGNs. The ensuing significant conductance changes resulted in reduced excitability in mechanosensitive Ttpa-/- DRGNs. A highly supplemented vitE diet (600 mg dl-α-tocopheryl acetate/kg diet) prevented the cellular and molecular alterations and improved mechanosensation. VitE deficiency profoundly alters the molecular signature and functional properties of mechanosensitive TH+ DRGN, representing an intriguing shift of the prevailing paradigm from proprioception to mechanical sensation

Geometrically Induced Multiple Coulomb Blockade Gaps

We have theoretically investigated the transport properties of a ring-shaped array of small tunnel junctions, which is weakly coupled to the drain electrode. We have found that the long range interaction together with the semi-isolation of the array bring about the formation of stable standing configurations of electrons. The stable configurations break up during each transition from odd to even number of trapped electrons, leading to multiple Coulomb blockade gaps in the the $I-V$ characteristics of the system.Comment: 4 Pages (two-columns), 4 Figures, to be published in Physical Review Letter