ドウテキ ページ ノ ゾウカ ガ モタラス Web リンク コウゾウ ノ ヘンカ

いくつかのWebサイト群に対してクローリングを行い、リンク構造を解析した。静的ページではリンクの確率密度分布が過去の研究同様べき乗則に従っていることと、inリンクの緊密度が動的ページに比べ高いことがわかった。一方動的ページでは、リンク確率密度分布がべき乗則に従っておらず、inのクラスター係数が著しく低かった。また、リンク数が多くなるにつれ、特にinのクラスター係数が高くなることを確認した。これによって、inのリンク数が多いページ同士は緊密なリンク関係にあることがわかった。この事実から、静的、動的ページかによってクロール手法を変えることによって効率的なクロール手法の開発につながると思われる。We performed crawling for several groups of Web sites and analyzed link structures. The probability density distribution of in-link showed the power-law which had been found in previous researches, and the closeness of in-link was found to be low in comparison with that of dynamic pages. On the other hand, in the dynamic pages, probability density distribution of links did not obey the power-law, and a clustering coefficient of in-link was remarkably low. Furthermore, we confirmed that particularly clustering coefficients of in-link increase as the number of the links increases. Therefore, it was found that the Web pages with many in-links have close relations mutually. These show a possible new crawling strategy that changes crawling methods by checking whether an Web page is static or dynamic

Identification of 45 New Neutron-Rich Isotopes Produced by In-Flight Fission of a 238U Beam at 345 MeV/nucleon

A search for new isotopes using in-flight fission of a 345 MeV/nucleon 238U beam has been carried out at the RI Beam Factory at the RIKEN Nishina Center. Fission fragments were analyzed and identified by using the superconducting in-flight separator BigRIPS. We observed 45 new neutron-rich isotopes: 71Mn, 73,74Fe, 76Co, 79Ni, 81,82Cu, 84,85Zn, 87Ga, 90Ge, 95Se, 98Br, 101Kr, 103Rb, 106,107Sr, 108,109Y, 111,112Zr, 114,115Nb, 115,116,117Mo, 119,120Tc, 121,122,123,124Ru, 123,124,125,126Rh, 127,128Pd, 133Cd, 138Sn, 140Sb, 143Te, 145I, 148Xe, and 152Ba

Essential Role of Neuron-Enriched Diacylglycerol Kinase (DGK), DGKβ in Neurite Spine Formation, Contributing to Cognitive Function

BACKGROUND: Diacylglycerol (DG) kinase (DGK) phosphorylates DG to produce phosphatidic acid (PA). Of the 10 subtypes of mammalian DGKs, DGKbeta is a membrane-localized subtype and abundantly expressed in the cerebral cortex, hippocampus, and caudate-putamen. However, its physiological roles in neurons and higher brain function have not been elucidated. METHODOLOGY/PRINCIPAL FINDINGS: We, therefore, developed DGKbeta KO mice using the Sleeping Beauty transposon system, and found that its long-term potentiation in the hippocampal CA1 region was reduced, causing impairment of cognitive functions including spatial and long-term memories in Y-maze and Morris water-maze tests. The primary cultured hippocampal neurons from KO mice had less branches and spines compared to the wild type. This morphological impairment was rescued by overexpression of DGKbeta. In addition, overexpression of DGKbeta in SH-SY5Y cells or primary cultured mouse hippocampal neurons resulted in branch- and spine-formation, while a splice variant form of DGKbeta, which has kinase activity but loses membrane localization, did not induce branches and spines. In the cells overexpressing DGKbeta but not the splice variant form, DGK product, PA, was increased and the substrate, DG, was decreased on the plasma membrane. Importantly, lower spine density and abnormality of PA and DG contents in the CA1 region of the KO mice were confirmed. CONCLUSIONS/SIGNIFICANCE: These results demonstrate that membrane-localized DGKbeta regulates spine formation by regulation of lipids, contributing to the maintenance of neural networks in synaptic transmission of cognitive processes including memory

Generation and Characterization of Conditional Heparin-Binding EGF-Like Growth Factor Knockout Mice

Recently, neurotrophic factors and cytokines have been shown to be associated in psychiatric disorders, such as schizophrenia, bipolar disorder, and depression. Heparin-binding epidermal growth factor-like growth factor (HB-EGF) is a member of the EGF family, serves as a neurotrophic molecular and plays a significant role in the brain. We generated mice in which HB-EGF activity is disrupted specifically in the ventral forebrain. These knockout mice showed (a) behavioral abnormalities similar to those described in psychiatric disorders, which were ameliorated by typical or atypical antipsychotics, (b) altered dopamine and serotonin levels in the brain, (c) decreases in spine density in neurons of the prefrontal cortex, (d) reductions in the protein levels of the NR1 subunit of the N-methyl-D-aspartate (NMDA) receptor and post-synaptic protein-95 (PSD-95), (e) decreases in the EGF receptor, and in the calcium/calmodulin-dependent protein kinase II (CaMK II) signal cascade. These results suggest the alterations affecting HB-EGF signaling could comprise a contributing factor in psychiatric disorder

メタンフェタミン誘発逆耐性現象における皮質-線条体グルタミン酸神経伝達に関する電気生理学的解析

緒言 第一章 メタンフェタミン誘発行動逆耐性モデルラットの作製 第二章 メタンフェタミン休薬時における線条体ニューロンのグルタミン酸受容体の変化に関する検討 第三章 メタンフェタミン休薬時におけるグルタミン酸神経伝達の可塑的変化に関する電気生理学的検討 総括Made available in DSpace on 2012-09-06T02:51:14Z (GMT). No. of bitstreams: 1 moriguchi.pdf: 11423244 bytes, checksum: 1d7752193eb9484ff3cfa95d90b7be8a (MD5) Previous issue date: 2001-03-2