6,031 research outputs found
Proline-rich tyrosine kinase 2 mediates gonadotropin-releasing hormone signaling to a specific extracellularly regulated kinase-sensitive transcriptional locus in the luteinizing hormone beta-subunit gene
No full textG protein-coupled receptor regulation of gene transcription primarily occurs through the phosphorylation of transcription factors by MAPKs. This requires transduction of an activating signal via scaffold proteins that can ultimately determine the outcome by binding signaling kinases and adapter proteins with effects on the target transcription factor and locus of activation. By investigating these mechanisms, we have elucidated how pituitary gonadotrope cells decode an input GnRH signal into coherent transcriptional output from the LH beta-subunit gene promoter. We show that GnRH activates c-Src and multiple members of the MAPK family, c-Jun NH2-terminal kinase 1/2, p38MAPK, and ERK1/2. Using dominant-negative point mutations and chemical inhibitors, we identified that calcium-dependent proline-rich tyrosine kinase 2 specifically acts as a scaffold for a focal adhesion/cytoskeleton-dependent complex comprised of c-Src, Grb2, and mSos that translocates an ERK-activating signal to the nucleus. The locus of action of ERK was specifically mapped to early growth response-1 (Egr-1) DNA binding sites within the LH beta-subunit gene proximal promoter, which was also activated by p38MAPK, but not c-Jun NH2-terminal kinase 1/2. Egr-1 was confirmed as the transcription factor target of ERK and p38MAPK by blockade of protein expression, transcriptional activity, and DNA binding. We have identified a novel GnRH-activated proline-rich tyrosine kinase 2-dependent ERK-mediated signal transduction pathway that specifically regulates Egr-1 activation of the LH beta-subunit proximal gene promoter, and thus provide insight into the molecular mechanisms required for differential regulation of gonadotropin gene expression
Validation of simulated real world TCP stacks
No full textThe TCP models in ns-2 have been validated and are widely used in network research. They are however not aimed at producing results consistent with a TCP implementation, they are rather designed to be a general model for TCP congestion control. The Network Simulation Cradle makes real world TCP implementations available to ns-2: Linux, FreeBSD and OpenBSD can all be simulated as easily as using the original simplified models. These simulated TCP implementations can be validated by directly comparing packet traces from simulations to traces measured from a real network. We describe the Network Simulation Cradle, present packet trace comparison results showing the high degree of accuracy possible when simulating with real TCP implementations and briefly show how this is reflected in a simulation study of TCP throughput
93.8% Current Efficiency and 0.672 ns Transient Response Reconfigurable LDO for Wireless Sensor Network Systems
No full textCurrent-efficient, fast-transient reconfigurable low-dropout regulator (LDO) is proposed for the wireless sensor network (WSN) system. The proposed LDO is designed and simulated in a 65 nm CMOS process showing the 3 key features: 1) a reconfigurable LDO architecture to achieve both low quiescent current (IQ) and wide bandwidth by adaptively adjusting to different load current conditions, 2) ultra-low-IQ and high PSR regulator for light-load efficient operation utilizing the gain boosting scheme within the flipped voltage follower loop, and 3) fast transient regulator for robust heavy-load operation with level-shifted impedance attenuation buffer (IAB) to reduce the supply ripples generated by wireless transceiver. The proposed LDO shows the state-of-the-art 93.8% current efficiency in the load condition of 1 µA, and achieves 0.672 ns response time even with 10 ns load transition
Arthrobacter pascens NS
No full textDescription of Arthrobacter pascens NS 4Y-8-4 Cells are Gramstainingpositive, nonflagellated and rod-shaped. Colonies are circular, entire, convex and white-colored after 2 days on R2A at 30°C. Positive for esculin hydrolysis and βgalactosidase in API 20NE but negative for nitrate reduction, indole production, glucose fermentation, arginine dihydrolase, urease and gelatinase. D-Glucose, L-arabinose, D-mannitol, D-mannose, N-acetyl-glucosamine, D-maltose, gluconate, malate and citrate are utilized. Does not utilize caprate, adipate and phenylacetate. Strain NS 4Y-8-4 (= NIBRBA 0000114873) has been isolated from ginseng soil, Anseong, Korea.Published as part of Ko, Kwan Su, Cha, Chang-Jun, Im, Wan-Taek, Kim, Seung-Bum, Seong, Chi-Nam, Bae, Jin-Woo, Jahng, Kwangyeop, Cho, Jang-Cheon, Joh, Ki-seong & Lee, Soon Dong, 2017, A report of 34 unrecorded bacterial species in Korea, belonging to the Actinobacteria, pp. 1-14 in Journal of Species Research 6 (1) on page 11, DOI: 10.12651/JSR.2017.6.1.001, http://zenodo.org/record/812037
A 0.7-fJ/bit/search 2.2-ns search time hybrid-type TCAM architecture
No full textThis paper presents a hybrid-type TCAM architecture which can utilize the benefits of both NOR and NAND-type TCAM cells: high speed and low power. A hidden bank selection scheme is proposed to activate limited amount of cells during the search operation avoiding additional timing penalty. Match line repeaters and sub-match line scheme are used for fast NAND search operation. A test chip with 144-kb TCAM capacity is implemented using 0.1-mum 1.2-V CMOS process to verify the proposed schemes. It shows 2.2 ns of match evaluation time on a 144-bit data search with 0.7 fJ/bitt/search energy efficiency
Just culture bij de NS
No full textIn een just culture heerst waardering voor openheid. In zo’n organisatiecultuur gaatmen rechtvaardig om met fouten en met medewerkers die bij een incident betrokken zijn. In dit artikel leest u hoe de NS probeert een just culture te ontwikkelen door middel van een leidraad.Safety and Security Scienc
ATF3 upregulation in glia during Wallerian degeneration: differential expression in peripheral nerves and CNS white matter
No full textBackground: Many changes in gene expression occur in distal stumps of injured nerves but the transcriptional control of these events is poorly understood. We have examined the expression of the transcription factors ATF3 and c-Jun by non-neuronal cells during Wallerian degeneration following injury to sciatic nerves, dorsal roots and optic nerves of rats and mice, using immunohistochemistry and in situ hybridization.Results: Following sciatic nerve injury-transection or transection and reanastomosis-ATF3 was strongly upregulated by endoneurial, but not perineurial cells, of the distal stumps of the nerves by 1 day post operation (dpo) and remained strongly expressed in the endoneurium at 30 dpo when axonal regeneration was prevented. Most ATF3+ cells were immunoreactive for the Schwann cell marker, S100. When the nerve was transected and reanastomosed, allowing regeneration of axons, most ATF3 expression had been downregulated by 30 dpo. ATF3 expression was weaker in the proximal stumps of the injured nerves than in the distal stumps and present in fewer cells at all times after injury. ATF3 was upregulated by endoneurial cells in the distal stumps of injured neonatal rat sciatic nerves, but more weakly than in adult animals. ATF3 expression in transected sciatic nerves of mice was similar to that in rats. Following dorsal root injury in adult rats, ATF3 was upregulated in the part of the root between the lesion and the spinal cord (containing Schwann cells), beginning at 1 dpo, but not in the dorsal root entry zone or in the degenerating dorsal column of the spinal cord. Following optic nerve crush in adult rats, ATF3 was found in some cells at the injury site and small numbers of cells within the optic nerve displayed weak immunoreactivity. The pattern of expression of c-Jun in all types of nerve injury was similar to that of ATF3.Conclusion: These findings raise the possibility that ATF3/c-Jun heterodimers may play a role in regulating changes in gene expression necessary for preparing the distal segments of injured peripheral nerves for axonal regeneration. The absence of the ATF3 and c-Jun from CNS glia during Wallerian degeneration may limit their ability to support regeneration
Ondertunneling van NS-sporen door een metrotunnel te Rotterdam
No full textOm de toekomstige groei van het autoverkeer in de stad in te dammen heeft gemeente Rotterdam besloten om het openbaar vervoer in de stad uit te breiden. Daarnaast moeten de verschillende vormen van openbaar vervoer beter op elkaar worden aangesloten. Een van de plannen om dit te realiseren is het metronet van de stad in noordelijke richting uit te breiden via Berkel en Rodenrijs naar Zoetermeer. In deze plaatsen moet een aansluiting komen op het NS-net. Het noordelijk deel van de huidige noord-zuidlijn in het Rotterdamse metronet eindigt in een tunnel onder het stationsplein bij het Centraal Station. Op die plaats moet een aansluiting worden gemaakt tussen de nieuwe en de bestaande tunnel. Vanaf deze plaats kruist het geplande tracé het NS-spooremplacement waarna de lijn in noordelijke richting zijn weg vervolgt. In dit rapport wordt verslag gedaan van een onderzoek naar de meest geschikte methode voor de realisatie van de metrotunnel ter plaatse van de kruising met het NS-spoor . Uitgangspunt daarbij is dat de aanleg geen problemen zal opleveren voor het NS treinverkeer. Tevens wordt het verschil in uitvoering tussen een 2- en een 3-sporentunnel met elkaar vergeleken. Belangrijkste conclusies: Het kruisen van het NS-spoor met een metrotunnel is met de openbouwkuipmethode goed mogelijk maar gaat gepaard met partiële buitendienststelling van de sporen, wat in zeer goed overleg met de NS moet gebeuren. Zodra de wanden van de kuip zijn aangebracht kan door een goede planning van de uitvoering gezorgd worden dat de NS geen verdere overlast ondervindt. Het aanleggen van een 3-sporenkuip geeft in vergelijking een 2-sporenkuip geen grote extra problemen. De werkzaamheden voor de aanleg van de kuip moeten allemaal onder de sporen door plaatsvinden zodat het treinverkeer zo min mogelijk wordt verstoord. Hier kan niet zoals gebruikelijk vanaf het maaiveld naast de kuip worden gewerkt, maar moet vanuit de kop worden gewerkt. Bij de kuip waarbij onderwaterbeton wordt toegepast geeft de uitvoering meer problemen omdat niet vanaf het maaiveld in de natte kuip kan worden gewerkt. Door gebruik te maken van een hulpmiddel die onder de stempels door beweegt, de zogenaamde "negatieve brugconstructie" , kunnen een aantal moeilijke handelingen tijdens de uitvoering veel makkelijker worden uitgevoerd. Met een dergelijke hulpconstructie neemt de kans toe dat een vloer van gewapend onderwaterbeton kan worden aangebracht die aan de eisen voldoet. Bij het maken van een keuze tussen een ongewapende vloer en een gewapende vloer wordt dan ook gekozen voor het gewapende alternatief. Om echter op deze plaats geen onnodige risico' s te nemen krijgt de vloer slechts een gedeeltelijke constructieve functie.WaterbouwHydraulic EngineeringCivil Engineering and Geoscience
CHANG JUN YOON
No full text학위논문(석사)--아주대학교 일반대학원 :분자과학기술학과,2006. 2Recent advances in the generation and amplification of ultrashort laser pulses are remarkable due to broad applications in many areas such as ultrafast spectroscopy, imaging and material processing. Recently, optical parametric chirped pulse amplification (OPCPA) turned out to be an efficient method to amplify ultrashort pulses. Using this technique, energies of intensive ns or sub-nanosecond (sub-ns) pump pulses can be efficiently transferred to the spatially and temporally synchronized stretched low-energy seed pulses in a suitable nonlinear crystal. OPCPA is a promising alternative to widely used regenerative and multi-pass amplifiers. It offers some advantages such as extremely broad gain bandwidth, high contrast ratio, low thermal effect, low nonlinear wavefront distortion and compact experimental performance without electro-optic modulators.
Looking at the recent progress in OPCPA, it was divided in two directions. The first trend was concentrated on the development of exceptionally high peak power (TW-level) laser systems at low repetition rates between single short to 10 Hz. Such high-energy OPCPA’s were seeded by pulses from Ti:sapphire laser at the degenerate point near 1 m. The second tendency was related to the development of more compact and stable fs OPCPA systems operating in kHz repetition rates with intermediate powers as alternative of regenerative and multi-pass amplifiers.
In this work, we report on experimental design and characteristics of a Cr:forsterite based OPCPA, what we believe to be the first demonstration in kHz repetition rates. Recently, a complex multi-cascade broadband Cr:forsterite OPCPA was demonstrated with slightly different pump and seed wavelengths to generate J-energies, but at a low repetition rate of 2 Hz. In this work, a kHz diode-pumped frequency-doubled Nd:YVO4 laser was used as pump laser delivering the shortest ns pulses (≤10 ns), up to now. Suitable gain medium was carefully selected by performing theoretical analysis of phase matching properties of different nonlinear crystals such as DKDP, KDP and BBO. Both collinear and noncollinear phase matching geometries were considered and characterized for broadband parametric process. The bandwidth broadening is a prior condition for generation of ultrashort pulses. It turned out that DKDP seems to be the best candidate for Cr:forsterite based OPCPA. Subsequently, first experiment results of the non-degenerate single-pass OPCPA delivering pulses near 935 nm and 1235 nm, respectively, were presented and discussed.목 차
국문요약 ⅰ
그림차례 ⅴ
표 차 례 ⅷ
1. 서론 1
1.1 역사 1
1.2 고출력 극초단 펄스 응용 3
1.3 광매개 처프 펄스 증폭법 5
1.4 연구 목적 8
2. 기본 이론 10
2.1 펄스압축기와 펄스늘임기 10
2.1.1 GVD(Group Velocity Dispersion) 11
2.1.2 프리즘 쌍 13
2.1.3 회절격자 쌍을 이용한 펄스압축기 16
2.1.4 회절격자 쌍을 이용한 펄스늘임기 19
2.2 광매개 이득 22
2.2.1 Noncollinear 위상정합 23
2.2.2 광매개 이득 25
2.2.3 군속도 부정합 26
3. 광매개 처프 펄스 증폭기 제작 28
3.1 공진기 특성 29
3.2 펄스늘임기와 펄스압축기 제작 32
3.2.1 펄스늘임기 수차분석을 위한 광경로 추적 32
3.2.2 펄스늘임기 37
3.2.3 펄스압축기 43
3.3 광매개 증폭기 구성 47
3.3.1 시간적 동기화 실현 47
3.3.2 비선형 단결정의 증폭 가능성 분석 50
3.3.3 DKDP를 이용한 증폭실험 61
4. 결론 및 향후 연구 방향 64
참고문헌 66
Abstract 71Maste
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