Bifurcation analysis in a silicon neuron

International audienceIn this paper, we describe an analysis of the nonlinear dynamical phenomenon associated with a silicon neuron. Our silicon neuron integrates Hodgkin-Huxley (HH) model formalism, including the membrane voltage dependency of temporal dynamics. Analysis of the bifurcation conditions allow us to identify different regimes in the parameter space that are desirable for biasing our silicon neuron. This approach of studying bifurcations is useful because it is believed that computational properties of neurons are based on the bifurcations exhibited by these dynamical systems in response to some changing stimulus. We describe numerical simulations and measurements of the Hopf bifurcation which is characteristic of class 2 excitability in the HH model. We also show a phenomenon observed in biological neurons and termed excitation block. Hence, by showing that this silicon neuron has similar bifurcations to a certain class of biological neurons, we can claim that the silicon neuron can also perform similar computation

Status of MSBS Study at NAL in 1995

Magnetic field intensity and currents passing through the coils of the National Aerospace Laboratory (NAL) 1O cm Magnetic Suspension and Balance System (MSBS) were measured while a cylindrical model was oscillated along x,y,z and also about y and z axes, respectively. The model was made of alnico 5 and was 8 mm in diameter and 60 mm long. Two kinds of tests were carried out. Amplitude of the oscillation was varied at a frequency of 10 Hz. Frequency was varied from 1 to 50 Hz in the other test. Results of the tests show that the relation between coil currents and magnetic force acting on the model is affected by frequency. They also show that the relation between measured magnetic field intensity and the force in vertical direction is independent of the frequency below 30 Hz. Using the measured magnetic field intensity, the vertical force can be evaluated at the MSBS instantaneously when a model moves at frequencies below 30 Hz. A static drag force calibration test was carried out at the 60 cm MSBS. Obtained relationships between measured drag coil currents and loads shows large hysteresis

人工種苗生産されたキジハタ仔稚魚の遊泳・摂餌関連形質の発達

人工種苗生産されたキジハタ仔稚魚について、遊泳と摂餌に関する形質の発育を記載し発育段階の設定を行った。遊泳では以下の5段階に分けられた：1）遊泳未発達期（D0～1）－遊泳に関する形質は出現しない時期；2）浮遊および胸鰭発達期（D2～9）－肩帯の構成要素が出現する時期；3）尾鰭推進準備期（D10－12～15－17）－脊索末端の上屈が開始・完了する時期；4）尾鰭＋体全体推進期（D15－17～20－22）－脊椎要素が出現・完成し、臀鰭と腹鰭、尾鰭の鰭条が定数になる時期；5）遊泳機能完成期（D20－22～）－稚魚としての遊泳能力が獲得される時期。摂餌でも以下の5段階に分けられた：1）摂餌未発達期（D0～2）－未開口で内部栄養に依存する時期；2）初期吸込み期（D3～9）－口腔を形成する要素が出現し、開口したことで陰圧を利用した摂餌が可能となる時期；3）吸込み摂餌期（D10－12～20－22）－口腔を形成する要素の化骨により吸込み機能が強化され、上顎に占める前上顎骨の長さが一定になることで口の開閉能力が増す時期；4）吸込み＋噛みつき期（D20－22～35）－摂餌関連形質はすべて出現・完成し、顎歯だけでなく前鋤骨歯や口蓋骨歯も出現する時期；5）摂餌機能完成期（D35～）－稚魚としての摂餌能力が獲得される時期。本研究の結果から、本種の初期飼育の困難さの一因が、内部栄養から外部栄養に切り替わる期間の遊泳・摂餌関連形質の発育の遅さであることが判明した。さらにD30を過ぎると、群れを形成するとともに、共食いの萌芽行動である「J字」ポーズが見られた。本研究の結果は、今後の本種をふくむハタ科魚類の種苗生産の新しい管理手法の開発に資すると期待される。Based on the development of swimming- and feeding-related characters, ontogenetic intervals of larvae and juveniles were investigated for hatchery-reared red spotted grouper, Epinephelus akaara. Five phases each were recognized for the development of swimming and feeding functions as follows. Swimming: 1) the phase with less active swimming (hatching to 1 day after hatching, D1); 2) the phase with body control by pectoral fins (D2～D9); 3) the phase with preparation of caudal fin propulsion (D10-12～D15-17); 4) the phase with caudal fin and whole body propulsion (D15-17～D20-22); 5) the phase of juvenile swimming mode (beyond D20-22). Feeding: 1) the phase with endogenous nutrient (hatching to D2); 2) the phase with initial feeding of sucking (D3～D9); 3) the phase with sucking ability increasing (D10-12～D20-22); 4) the phase with sucking and initial biting (D20-22～D35); 5) the phase of juvenile feeding mode (beyond D35). The present study revealed that the difficulties of larval rearing of the species would be partly due to the delay of development of characters related to swimming- and feeding-functions during the changeover from endogenous to exogenous feeding. After D30, the juveniles with functional swimming- and feeding-mode showed both swimming in schools and posing with “J-posture”, the latter being considered to be the onset of cannibalistic behavior. The results of present study are expected to contribute to the improvement of larval rearing system in groupers.今井 智・小金隆之・山下貴示: 国立研究開発法人水産研究・教育機構瀬戸内海区水産研究所資源生産部Satoshi IMAI, Takayuki KOGANE, Takashi YAMASHITA: Stock Enhancement and Aquaculture Department, National Research Institute of Fisheries and Environment of Inland Sea, Fisheries Research and Education Agency河野 博: 東京海洋大学学術研究院海洋環境科学部門 魚類学研究室Hiroshi KOHNO: Laboratory of Ichthyology, Department of Ocean Sciences, Tokyo University of Marine Science and Technology (TUMSAT

New 60-cm Radio Survey Telescope with the Sideband-Separating SIS Receiver for the 200 GHz Band

We have upgraded the 60-cm radio survey telescope located in Nobeyama, Japan. We developed a new waveguide-type sideband-separating SIS mixer for the telescope, which enables the simultaneous detection of distinct molecular emission lines both in the upper and lower sidebands. Over the RF frequency range of 205-240 GHz, the single-sideband receiver noise temperatures of the new mixer are 40-100 K for the 4.0-8.0 GHz IF frequency band. The image rejection ratios are greater than 10 dB over the same range. For the dual IF signals obtained by the receiver, we have developed two sets of acousto-optical spectrometers and a telescope control system. Using the new telescope system, we successfully detected the 12CO (J=2-1) and 13CO (J=2-1) emission lines simultaneously toward Orion KL in 2005 March. Using the waveguide-type sideband-separating SIS mixer for the 200 GHz band, we have initiated the first simultaneous 12CO (J=2-1) and 13CO (J=2-1) survey of the galactic plane as well as large-scale mapping observations of nearby molecular clouds.Comment: 15 pages, 15 figures, Accepted for publication in PASJ, version with high resolution figures is available via http://www.nro.nao.ac.jp/~nakajima/vst1_2sb.pd

Dissection of lung parenchyma using electrocautery is a safe and acceptable method for anatomical sublobar resection

BACKGROUND: Anatomic sublobar resection is being assessed as a substitute to lobectomy for primary lung cancers. However, persistent air leak after anatomic sublobar resection is prevalent and increasing surgical morbidity and costs. The use of electrocautery is being popularized recently in anatomic sublobar resection. We have retrospectively evaluated the safety and efficacy of intersegmental plane dissection using electrocautery. METHODS: Between April 2009 to September 2010, 47 patients were treated with segmentectomy for clinical T1N0M0 non-small cell lung cancers. The intersegmental plane was dissected using electrocautery alone or in combination with staplers. We evaluated the methods of dividing intersegmental plane (electrocautery alone or combination with electrocautery and staplers), intraoperative blood loss, duration of chest tube placement, duration of surgery, preoperative FEV(1.0) %, incidence of prolonged air leak, length of postoperative hospital stay, postoperative pulmonary function at 6 months after surgery and the cost for sealing intersegmental plane. RESULTS: Among the 47 patients, 22 patients underwent intersegmental plane dissection with electrocautery alone and 25 patients did in combination with electrocautery and staplers. The mean number of stapler cartridges used was only 1.3 in electrocautery and staplers group. Mean age, gender, number of patients whose FEV(1)% < 70 % were similar between two groups. There was no statistical difference between electrocautery alone and combination with electrocautery and staplers group in duration of surgery (282 vs. 290 minutes), intraoperative blood loss (203 vs.151 ml), duration of chest tube placement (3.2 vs. 3.1 days), postoperative hospital stay (11.0 vs.10.0 days), postoperative loss of FEV(1.0) (13 vs.8 %), loss of FVC (11 vs. 6 %) or incidence of minor postoperative complications [9 % (2/22) vs. 16 % (4/25), p = 0.30)]. However, incidence of prolonged air leak was higher in electrocautery alone group than in combination with electrocautery and staplers group [14 % (3/22) vs. 4 % (1/25), p = 0.025)]. The cost of materials for sealing air leaks amounted to €964 per patient in the electrocautery alone group and €1594 per patient in combination with electrocautery and staplers group. CONCLUSIONS: The number of patients with prolonged air leak was higher in the electrocautery alone group. The use of staplers in addition to electrocautery may lead to reduced prolonged air leak. However, the use of electrocautery for intersegmental plane dissection appeared to be safe with acceptable postoperative complications and effective in reducing costs

Inhibition of the mitochondria-shaping protein Opa1 restores sensitivity to Gefitinib in a lung adenocarcinomaresistant cell line

Drug resistance limits the efficacy of chemotherapy and targeted cancer treatments, calling for the identification of druggable targets to overcome it. Here we show that the mitochondria-shaping protein Opa1 participates in resistance against the tyrosine kinase inhibitor gefitinib in a lung adenocarcinoma cell line. Respiratory profiling revealed that oxidative metabolism was increased in this gefitinib-resistant lung cancer cell line. Accordingly, resistant cells depended on mitochondrial ATP generation, and their mitochondria were elongated with narrower cristae. In the resistant cells, levels of Opa1 were increased and its genetic or pharmacological inhibition reverted the mitochondrial morphology changes and sensitized them to gefitinib-induced cytochrome c release and apoptosis. In vivo, the size of gefitinib-resistant lung orthotopic tumors was reduced when gefitinib was combined with the specific Opa1 inhibitor MYLS22. The combo gefitinib-MYLS22 treatment increased tumor apoptosis and reduced its proliferation. Thus, the mitochondrial protein Opa1 participates in gefitinib resistance and can be targeted to overcome it