Ordinary Differential Equation-based Sparse Signal Recovery

This study investigates the use of continuous-time dynamical systems for sparse signal recovery. The proposed dynamical system is in the form of a nonlinear ordinary differential equation (ODE) derived from the gradient flow of the Lasso objective function. The sparse signal recovery process of this ODE-based approach is demonstrated by numerical simulations using the Euler method. The state of the continuous-time dynamical system eventually converges to the equilibrium point corresponding to the minimum of the objective function. To gain insight into the local convergence properties of the system, a linear approximation around the equilibrium point is applied, yielding a closed-form error evolution ODE. This analysis shows the behavior of convergence to the equilibrium point. In addition, a variational optimization problem is proposed to optimize a time-dependent regularization parameter in order to improve both convergence speed and solution quality. The deep unfolded-variational optimization method is introduced as a means of solving this optimization problem, and its effectiveness is validated through numerical experiments.Comment: 13 page

Gradient Flow Decoding for LDPC Codes

The power consumption of the integrated circuit is becoming a significant burden, particularly for large-scale signal processing tasks requiring high throughput. The decoding process of LDPC codes is such a heavy signal processing task that demands power efficiency and higher decoding throughput. A promising approach to reducing both power and latency of a decoding process is to use an analog circuit instead of a digital circuit. This paper investigates a continuous-time gradient flow-based approach for decoding LDPC codes, which employs a potential energy function similar to the objective function used in the gradient descent bit flipping (GDBF) algorithm. We experimentally demonstrate that the decoding performance of the gradient flow decoding is comparable to that of the multi-bit mode GDBF algorithm. Since an analog circuit of the gradient flow decoding requires only analog arithmetic operations and an integrator, future advancements in programmable analog integrated circuits may make practical implementation feasible.Comment: 6 page

Two different classes of co-occurring motif pairs found by a novel visualization method in human promoter regions

<p>Abstract</p> <p>Background</p> <p>It is essential in modern biology to understand how transcriptional regulatory regions are composed of <it>cis</it>-elements, yet we have limited knowledge of, for example, the combinational uses of these elements and their positional distribution.</p> <p>Results</p> <p>We predicted the positions of 228 known binding motifs for transcription factors in phylogenetically conserved regions within -2000 and +1000 bp of transcriptional start sites (TSSs) of human genes and visualized their correlated non-overlapping occurrences. In the 8,454 significantly correlated motif pairs, two major classes were observed: 248 pairs in Class 1 were mainly found around TSSs, whereas 4,020 Class 2 pairs appear at rather arbitrary distances from TSSs. These classes are distinct in a number of aspects. First, the positional distribution of the Class 1 constituent motifs shows a single peak near the TSSs, whereas Class 2 motifs show a relatively broad distribution. Second, genes that harbor the Class 1 pairs are more likely to be CpG-rich and to be expressed ubiquitously than those that harbor Class 2 pairs. Third, the 'hub' motifs, which are used in many different motif pairs, are different between the two classes. In addition, many of the transcription factors that correspond to the Class 2 hub motifs contain domains rich in specific amino acids; these domains may form disordered regions important for protein-protein interaction.</p> <p>Conclusion</p> <p>There exist at least two classes of motif pairs with respect to TSSs in human promoters, possibly reflecting compositional differences between promoters and enhancers. We anticipate that our visualization method may be useful for the further characterisation of promoters.</p

Brain Activation During Autobiographical Memory Retrieval with Special Reference to Default Mode Network

Recent neuroimaging studies have suggested that brain regions activated during retrieval of autobiographical memory (ABM) overlap with the default mode network (DMN), which shows greater activation during rest than cognitively demanding tasks and is considered to be involved in self-referential processing. However, detailed overlap and segregation between ABM and DMN remain unclear. This fMRI study focuses first on revealing components of the DMN which are related to ABM and those which are unrelated to ABM, and second on extracting the neural bases which are specifically devoted to ABM. Brain activities relative to rest during three tasks matched in task difficulty assessed by reaction time were investigated by fMRI; category cued recall from ABM, category cued recall from semantic memory, and number counting task. We delineated the overlap between the regions that showed less activation during semantic memory and number counting relative to rest, which correspond to the DMN, and the areas that showed greater or less activation during ABM relative to rest. ABM-specific activation was defined as the overlap between the contrast of ABM versus rest and the contrast of ABM versus semantic memory. The fMRI results showed that greater activation as well as less activation during ABM relative to rest overlapped considerably with the DMN, indicating that the DMN is segregated to the regions which are functionally related to ABM and the regions which are unrelated to ABM. ABM-specific activation was observed in the left-lateralized brain regions and most of them fell within the DMN

An fMRI Study of Word Reading and Colour Recognition in Different Quadrant Fields

This fMRI study analyzed activations for processing of word and colour, which were presented in each of the four quadrants, to investigate anatomical segregation between colour and orientation processing and also to examine the effect of visual stimulus position on brain activations. Main effect of visual category was found in the bilateral extrastriate cortices extending to the left visual word form area (word > colour) and small area of the right ventrolateral prefrontal cortex (colour > word). ROI analysis showed that there was a tendency that V4α, not V4/8, showed a greater response to colours than to words. Main effect of visual fields was found in early visual areas, which showed greater responses to the left than to the right field stimuli and also to the lower than to the upper field stimuli. No significant interactions between visual category and visual fields were found

気管支喘息の low attenuation are (LAA) に対する長期喫煙の影響-4年間の経過観察-

Background-The influence of cigarette smoking on the pathogenesis of asthma in the elderly remains controversial. This study attempts to estimate longitudinal changes in HRCT (high resolution computed tomography) parameters and pulmonary function parameters obtained for ex-smokers and never-smokers in asthmatics during 4-yr follow-up period. Methods-Fourteen asthmatics (6 ex-smokers and 8 never-smokers) were studied to determine the influence of aging and cigarette smoking on pulmonary function, and mean lung density (MLD) and the relative area of the lung showing attenuation values less than -950 HU (RA950) on HRCT scans. Results-The values of FVC and FEV1, were significantly more decreased in asthmatics without a smoking history during 4-yr follow-up period. The values of FVC, FEV1, FEV1/FVC and DLco/VA were significantly decreased and RV/TLC were significantly increased in asthmatics with a smoking history over 4 years, and annual decline in FEV1 ex-smokers was larger than that in never-smokers. In the upper lung field, inspiratory MLD was observed to shift in a negative direction and inspiratory RA950 was found to increase during 4-yr observation period in ex-smokers, but not in never-smokers. In the middle lung field, inspiratory RA950 was significantly enhanced in both two groups. Although expiratory MLD, expiratory RA950 and exp RA950/ins RA950 were observed to change significantly during the observation period in ex-smokers, no changes were observed in never-smokers. Conclusion-These results suggest that aging augments airspace enlargement predominantly in the middle lung field, while long term cigarette smoking further worsens emphysematous alterations in the upper lung field.気管支喘息患者の肺高分解能CT所見に対する長期喫煙の影響を検討することを目的とした｡非喫煙喘息患者8名,喫煙歴を有する喘息患者6名を対象として,肺機能,肺平均CT値(MLD),-950HU以下のlow attenuation area(RA(950))について4年間の経過観察を行った｡ 4年間の観察中,非喫煙喘息患者では努力肺活量,1秒量の低下を認めた｡喫煙歴を有する喘息患者では努力肺活量,1秒量,1秒率,肺拡散能 の低下および残気率の増加を認めた｡喫煙歴を有する喘息患者では吸気において,上肺野MLDの有意の低下,RA(950)の有意の上昇を認めたが,非喫煙喘息患者では有意の変化は認めなかった｡中肺RA(950)は喫煙歴を有する喘息患者,非喫煙喘息患者ともに有意の上昇を認めた｡また,呼気において,喫煙歴を有する喘息患者でMLDの有意の低下,RA(950)の有意の上昇を認めたが,非喫煙喘息患者では有意の変化は認めなかった｡喘息患者において,加齢は主に中肺野のlow atenuation area,喫煙は上肺野のlow atenuation areaに影響を及ぼすことが示唆された

Cryogenic deuterium target experiments with the GEKKO XII, green laser system

Copyright 1995 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in Physics of Plasmas, 2(6), 2495-2503, 1995 and may be found at http://dx.doi.org/10.1063/1.87121

HRCT上の肺のLow Attenuation Areaおよび肺機能により評価された高齢者善喘息の特徴

The clinical significance of low attenuation area <-950 HU of the lungs on high - resolution computed tomography (HRCT) was evaluated in 80 patients with asthma in relation to patient age, CT number, pulmonary function including % residusal volume (% RV) and % DLco, and generation of leukotrienes B4 and C4 by leucocytes. 1. The % LAA (<- 950 HU) of the lungs showed a tendency to increase significantly with aging; the % LAA was significantly larger in elderly patients over the age of 60 years than in those under the age of 49 years. The CT number was also significantlyincreased with aging. 2. The values of % FVC, % FEV1.0, and FEV1.0% were significantly decreased in elderly patients over age 70 compared with the values in those under age 49. 3. The value of % residual volume (% RV) tended to increase significantly with aging; the value in patients over the age of 70 years was significantly larger in those between the ages of 50 and 59 (p<O.OOl). and under the age of 49 years (p<O.OOl). 4. The % DLco value significantly decreased with aging; the value in patients over age 70 was significantly lower than the value in those between the ages of 50 and 59 (p<O.Ol) and under age 49 (p<O.OOl). 5. A significant correlation was observed between % LAA of the lungs and % RV (r=O. 67, p<0.001), however. any significant correlations were not observed between % LAA and the values of % FVC, % FEV1.0, and FEV1.0% . 6. The generation of LTB4 and LTC4 by leucocytes was not significantly related with patient age. The results suggested that % LAA of the lungs on HRCT tended to increse with aging, accompanied with a significant increase in % RV.気管支喘息80例(全例非喫煙者)を対象に,high resolution computedt omography (HRCT)上の肺の-950HU以下のLow attenuation area (LAA)の臨床的意義について, 患者年齢, CT number,残気率(% RV),拡散能(% DLco)を含む肺機能検査,白血球のコイコトリエンB4,C4の産生能などとの関連のもとに検討を加えた｡ 1.% LAAは,年齢が高くなるにつれて増加する傾向を示し,60才以上の症例の% LAAは,49歳以下の症例に比べ有意に高い値を示した｡また,CT numberも,年齢が高くなるにつれて有意の増加を示した｡ 2.% FVC,% FEV1.0およびFEV1.0%値は,いずれも70才以上の症例で49歳以下の症例に比べ有意に低い値を示した｡ 3.残気率(% RV)は,年齢が高くなるにつれて増加する傾向を示し,70才以上の症例の% RVは,50-59才および49才以下の症例の% RVに比べ有意に高い値を示した｡ 4.一方,拡散能(% DLco)は,年齢が高くなるにつれて有意に低下する傾向を示し,70才以上の症例の% DLcoは,50-59才および49才以下の症例のDLcoに比べ有意に低い値を示した｡ 5.% LAAと% RVとの間には有意の相関が見られたが,% LAAと% DLco,および% LAAと換気機能(% FVC,% FEV1.0,FEV1.0%)との間には関連は見られなかった｡ 6.白血球のLTB4およびLTC4の産生能においては年齢による差は見られなかった｡これらの結果は,% LAAが年齢とともに増加すること,そして% LAAは% RVと密接な関連を有していることを示している

Multidetector-CT findings of dissecting aortic aneurysum and coronary artery disease. Based on the case of dissecting aortic aneurysum and coronary artery disease.

2000年になり多列検出器高速CT (Multi-detector CT,以下MDCT)が出現し,大動脈疾患や心電図同期での冠動脈狭窄病変診断への臨床応用が開始された.当院でも2001年7月からMDCTが稼動し,日常臨床診療に貢献している. 今回,解離性上行大動脈瘤(DeBakeyII)(以下DAA)と冠動脈疾患(LAD# 7の閉塞)を合併した患者を診療した.MDCTによるCT - Angiography (以下CTA)が両者の診断に非常に有用であった.患者の負担は100mlの末梢静脈内への造影剤の投与と約数十秒間の呼吸停止だけで,解離性大動脈瘤並びに冠動脈狭窄病変の診断にそれぞれ非常に有用であった.三次元診断の鮮明な画像が得られ,かつ低侵襲度のMDCT並びにCTAは,今後益々臨床の場で血管造影検査の強力なファーストチョイスの診療手段になると考える.Multidetector-CT (MDCT) and CT-Angio hase proven to be extremely useful in diagnosis of dissecting aortic aneurysum (DM) and coronary artery disease (CAD) . We report a case of DM complicated with CAD which was diagnosed by new MDCT