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Search Results: 1 - 10 of 2810 matches for " Naohiko Kobayashi "
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Ultra-Wideband Time-of-Arrival and Angle-of-Arrival Estimation Using Transformation Between Frequency and Time Domain Signals
Naohiko Iwakiri,Takehiko Kobayashi
Journal of Communications , 2008, DOI: 10.4304/jcm.3.1.12-19
Abstract: This paper presents an ultra wideband (UWB) channel sounding scheme with a technique for time of arrival (TOA) and angle of arrival (AOA) estimation using transformation between time and frequency domain signals. Since the measured UWB power spectrum can be transformed into a time domain signal, both frequency and time domain signals are available for the channel estimation. We propose the TOA estimation using a peak search over time domain signal, and the AOA estimation using MUSIC and AOA histograms. The AOA histogram is counted for AOA samples of discrete frequencies over the UWB bandwidth. Comparing both AOA histograms before and after TOA subtraction, we can determine pairing the elements of TOA vector and those of AOA vector. The anechoic chamber tests indicated that both TOAs and AOAs were precisely resolved for two-path model, even if either TOAs or AOAs were too close to resolve.
Performance Analysis of Ultra-Wideband Channel for Short-Range Monopulse Radar at Ka-Band
Naohiko Iwakiri,Natsuki Hashimoto,Takehiko Kobayashi
Journal of Electrical and Computer Engineering , 2012, DOI: 10.1155/2012/710752
Abstract: High-range resolution is inherently provided with Ka-band ultra-wideband (UWB) vehicular radars. The authors have developed a prototype UWB monopulse radar equipped with a two-element receiving antenna array and reported its measurement results. In this paper, a more detailed verification using these measurements is presented. The measurements were analyzed employing matched filtering and eigendecomposition, and then multipath components were extracted to examine the behavior of received UWB monopulse signals. Next, conventional direction finding algorithms based on narrowband assumption were evaluated using the extracted multipath components, resulting in acceptable angle-of-arrival (AOA) from the UWB monopulse signal regardless of wideband signals. Performance degradation due to a number of averaging the received monopulses was also examined to design suitable radar's waveforms.
Resurrection of a Bull by Cloning from Organs Frozen without Cryoprotectant in a ?80°C Freezer for a Decade
Yoichiro Hoshino, Noboru Hayashi, Shunji Taniguchi, Naohiko Kobayashi, Kenji Sakai, Tsuyoshi Otani, Akira Iritani, Kazuhiro Saeki
PLOS ONE , 2009, DOI: 10.1371/journal.pone.0004142
Abstract: Frozen animal tissues without cryoprotectant have been thought to be inappropriate for use as a nuclear donor for somatic cell nuclear transfer (SCNT). We report the cloning of a bull using cells retrieved from testicles that had been taken from a dead animal and frozen without cryoprotectant in a ?80°C freezer for 10 years. We obtained live cells from defrosted pieces of the spermatic cords of frozen testicles. The cells proliferated actively in culture and were apparently normal. We transferred 16 SCNT embryos from these cells into 16 synchronized recipient animals. We obtained five pregnancies and four cloned calves developed to term. Our results indicate that complete genome sets are maintained in mammalian organs even after long-term frozen-storage without cryoprotectant, and that live clones can be produced from the recovered cells.
Mapping and Exome Sequencing Identifies a Mutation in the IARS Gene as the Cause of Hereditary Perinatal Weak Calf Syndrome
Takashi Hirano, Naohiko Kobayashi, Tamako Matsuhashi, Daisaku Watanabe, Toshio Watanabe, Akiko Takasuga, Mayumi Sugimoto, Yoshikazu Sugimoto
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0064036
Abstract: We identified an IARS (isoleucyl-tRNA synthetase) c.235G>C (p.Val79Leu) substitution as the causative mutation for neonatal weakness with intrauterine growth retardation (perinatal weak calf syndrome). In Japanese Black cattle, the syndrome was frequently found in calves sired by Bull A. Hence, we employed homozygosity mapping and linkage analysis. In order to identify the perinatal weak calf syndrome locus in a 4.04-Mb region of BTA 8, we analysed a paternal half-sibling family with a BovineSNP50 BeadChip and microsatellites. In this critical region, we performed exome sequencing to identify a causative mutation. Three variants were detected as possible candidates for causative mutations that were predicted to disrupt the protein function, including a G>C (p.Val79Leu) mutation in IARS c.235. The IARS c.235G>C mutation was not a homozygous risk allele in the 36 healthy offspring of Bull A. Moreover, the IARS Val79 residue and its flanking regions were evolutionarily and highly conserved. The IARS mutant (Leu79) had decreased aminoacylation activity. Additionally, the homozygous mutation was not found in any of 1526 healthy cattle. Therefore, we concluded that the IARS c.235G>C mutation was the cause of hereditary perinatal weak calf syndrome.
BLV-CoCoMo-qPCR: a useful tool for evaluating bovine leukemia virus infection status
Mayuko Jimba, Shin-nosuke Takeshima, Hironobu Murakami, Junko Kohara, Naohiko Kobayashi, Tamako Matsuhashi, Takashi Ohmori, Tetsuo Nunoya, Yoko Aida
BMC Veterinary Research , 2012, DOI: 10.1186/1746-6148-8-167
Abstract: BLV-CoCoMo-qPCR was found to be highly sensitive when compared with the real-time PCR-based TaqMan MGB assay developed by Lew et al. and the commercial TaKaRa cycleave PCR system. The BLV copy number determined by BLV-CoCoMo-qPCR was only partially correlated with the positive rate for anti-BLV antibody as determined by the enzyme-linked immunosorbent assay, passive hemagglutination reaction, or agar gel immunodiffusion. This result indicates that, although serotests are widely used for the diagnosis of BLV infection, it is difficult to detect BLV infection with confidence by using serological tests alone. Two cattle were experimentally infected with BLV. The kinetics of the provirus did not precisely correlate with the change in anti-BLV antibody production. Moreover, both reactions were different in cattle that carried different bovine leukocyte antigen (BoLA)-DRB3 genotypes.Our results suggest that the quantitative measurement of proviral load by BLV-CoCoMo-qPCR is useful tool for evaluating the progression of BLV-induced disease. BLV-CoCoMo-qPCR allows us to monitor the spread of BLV infection in different viewpoint compared with classical serotest.Bovine leukemia virus (BLV) is associated with enzootic bovine leucosis (EBL) [1], which is the most common neoplastic disease of cattle. Infection by BLV can remain clinically silent, with cattle in an aleukemic state. Alternatively, it can emerge as persistent lymphocytosis (PL), characterized by an increased number of B lymphocytes, and, more rarely, as B-cell lymphomas in various lymph nodes after a long latent period [2]. Sheep that are experimentally inoculated with BLV develop B-cell tumors at a higher frequency and with a shorter latent period than naturally infected cattle [2,3].BLV is closely related to human T-cell leukemia virus types 1 and 2 (HTLV-1 and ?2), which are associated with adult T-cell leukemia (ATL) and with the chronic neurological disorder tropical spastic paraparesis/HTLV-1-associated myelo
Online connection for remittances
Naohiko Omata
Forced Migration Review , 2011,
Abstract: Internet cafés in refugee camps allow refugees to maintain and create networks for overseas remittances. For those who rely on receiving money from overseas...
The contact structure on the link of a cusp singularity
Naohiko Kasuya
Mathematics , 2012,
Abstract: We show that the contact structure on the link of a cusp singularity is contactomorphic to a Sol-manifold with the positive contact structure arising from the Anosov flow.
An obstruction for existence of codimension two contact embeddings in a Darboux chart
Naohiko Kasuya
Mathematics , 2013,
Abstract: We prove the vanishing of the first Chern class of a codimension 2 closed contact submanifold of a cooriented contact manifold with trivial integral 2-dimensional cohomology group. Hence the first Chern class is an obstruction for the existence of codimension 2 contact embeddings in a Darboux chart. For the existence of such an embedding, we prove that a closed cooriented contact 3-manifold can be a contact submanifold of the 5-dimensional Euclidean space for a certain contact structure, if its first Chern class vanishes.
Association between Systolic Blood Pressure Difference ≥10 mm Hg and Ankle-Brachial Index  [PDF]
Shinji Maeda, Yuzo Okumura, Naohiko Hara
International Journal of Clinical Medicine (IJCM) , 2016, DOI: 10.4236/ijcm.2016.75039
Abstract: Background: In new outpatients, blood pressure should be measured in both arms. A previous study reported that an inter-arm systolic blood pressure difference (ΔSBP) of ≥10 mm Hg is associated with an increased risk of mortality. Aim: The aim was to identify the associations with absolute values of ΔSBP (|ΔSBP|) ≥10 mm Hg. Subjects and Methods: This study included 2481 patients. Patients with a body mass index ≥25 kg/m2 were defined as obese. The group of A was defined as following: ankle-brachial index (ABI) was <0.9 or ≥1.3. ΔSBP was expressed as right arm BP minus left arm BP. |ΔSBP| ≥10 mm Hg were analyzed using multivariate logistic analysis. Results: |ΔSBP| ≥10 mm Hg was found in 6.0% of patients and |ΔSBP| < 5 mm Hg in 80.4%. In multivariate analysis, the odds ratios (ORs) of the associations with |ΔSBP| ≥10 mm Hg were significantly associated with abnormal ABI and obesity regardless of sex and age. Moreover, the OR of the combined effects of abnormal ABI and obesity was higher than that of abnormal ABI and obesity alone. Conclusion: |ΔSBP| ≥10 mm Hg was associated with abnormal ABI and obesity. In a primary care setting, blood pressure should be actively measured in both arms. This study suggests that the associations with |ΔSBP| ≥10 mm Hg may be a useful part of screening for abnormal ABI.
C2-Alkylation of N-pyrimidylindole with vinylsilane via cobalt-catalyzed C–H bond activation
Zhenhua Ding,Naohiko Yoshikai
Beilstein Journal of Organic Chemistry , 2012, DOI: 10.3762/bjoc.8.174
Abstract: Direct C2-alkylation of an indole bearing a readily removable N-pyrimidyl group with a vinylsilane was achieved by using a cobalt catalyst generated in situ from CoBr2, bathocuproine, and cyclohexylmagnesium bromide. The reaction allows coupling between a series of N-pyrimidylindoles and vinylsilanes at a mild reaction temperature of 60 °C, affording the corresponding alkylated indoles in moderate to good yields.
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