ACCELERATING FRAMES OF REFERENCE AND THE CLOCK PARADOX
Coordinate transformation between inertial reference system and noninertial acceleration system - clock paradox
INERTIAL REFERENCE SYSTEM↗
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Results for “Clock”
Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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A commandable tape-recorder delay timer and clock system for ae-b
Commandable tape recorder delay timer and clock system for Atmospheric Explorer Satellite AE-B
TAPE RECORDER↗
Entrainment in solution of an oscillating NADH oxidase activity from the bovine milk fat globule membrane with a temperature-compensated period length suggestive of an ultradian time-keeping (clock) function
Entrainment in solution of an oscillating activity with a temperature compensated period of 24 min is described for a NADH oxidase (NOX) activity of the bovine milk fat globule membrane, a derivative of the mammary epithelial cell plasma membrane. The period of 24 min remained unchanged at 17 degrees C, 27 degrees C and 37 degrees C whereas the amplitude approximately doubled with each 10 degree C rise in temperature (Q(10)congruent with 2). The periodicity was observed with both intact milk fat globule membranes and with detergent-solubilized membranes, demonstrating that the oscillations did not require an association with membranes. The periodicity was not the result of instrument variation or of chemical interactions among reactants in solution. Preparations with different periodicities entrained (autosynchronized) when mixed. Upon mixing, the preparations exhibited two oscillatory patterns but eventually a single pattern representing the mean of the farthest separated maxima of the two preparations analyzed separately emerged. The cell surface NOX protein is the first reported example of an entrainable biochemical entity with a temperature-compensated periodicity potentially capable of functioning as an ultradian or circadian clock driver.
Non-NASA Center↗
Stability measurements between Hg+ LITE 12-pole clocks
We describe frequency stability measurements of two Hg-ion clocks based upon linear 12-pole shuttle ion traps.
Hg LITE 12-pole clocks stability measurements↗
Development of flight technology for future laser-cooled space clocks
In this paper we report on the development of flight technologies to be used in space-based, laser-cooled atomic clocks scheduled to fly on the International Space Station.
atomIC clocks frequency standards microgravity↗
An Adaptive Method for Reducing Clock Skew in an Accumulative Z-Axis Interconnect System
This paper will present several methods for adjusting clock skew variations that occur in an accumulative Z-axis interconnect system.
3-D MCM Z-Axis Clock Skew↗
Applications of Advanced Clocks for Space Navigation and Communication
Precision clocks and frequency standards are widely used in communications and navigations systems.
Advanced Clocks Space Navigation Communication↗
Phase modulation with independent cavity-phase control in laser-cooled clocks in space
This paper discusses future phase modulations with independent cavity-phase control in laser cooled clocks in space.
frequency standards phase modulation atomic clock↗
Optimal Prediction of Clocks from Finite Data
This talk is about optimal linear prediction of processes with stationary dth increments, which serve as a class of models for random clock disturbances. The predictor is obtained by orthogonal projection on the affine space of estimators whose errors are invariant to additive polynomials of degree < d. The projection conditions give a system of linear equations thatcan be solved straightforwardly for the regression coefficients. If the data are equally spaced, then the predictor can be obtained by an extension of Levinson's algorithm.
stationary increments↗
Optimal Estimation of Clock Values and Trends from Finite Data
We show how to solve two problems of optimal linear estimation from a finite set of phase data. Clock noise is modeled as a stochastic process with stationary dth increments. The covariance properties of such a process are contained in the generalized autocovariance function (GACV). We set up two principles for optimal estimation: with the help of the GACV, these principles lead to a set of linear equations for the regression coefficients and some auxiliary parameters. The mean square errors of the estimators are easily calculated. The method can be used to check the results of other methods and to find good suboptimal estimators based on a small subset of the available data.
stationary increments↗
Clock Synchronization
Experimental goals are: (1) synchronize 1 pulse per second outputs derived from two different crystal oscillator sources, (2) generate near atomic clock accuracy for other experimental needs.
atomic clock↗
Revisions to Conventional Clock Domain Crossing Methodologies in Triple Modular Redundant Circuits
We present updates to the conventional methodology of triple modular redundancy (TMR) insertion as it pertains to clock domain crossings (CDCs). Three types of TMR schemes and their suggested corresponding CDC revisions are discussed.
Triple Modular Redundancy (TMR)↗
Clocks and oscillators in space
In this paper a short review of the role of clocks and oscillators in space is presented, together with some future projections for laser based systems.
clocks↗
Characteristics and Applications of Precise GPS Clock Solutions Every 30 Seconds
Using carrier pahse and pseudorange data from a small network of globally distributed GPS receivers with precise tiem references, we are able to estimate GPS clock parameters every 30 sec, with sub-decimeter accuracy, in a computationally efficent manner.
GPS↗
Angiographic Anatomy and Relevance of 3 and 9 O’clock Arteries During Radioembolization
Purpose3 and 9 o’clock arteries (3&9As) which supply the common hepatic duct connect hepatic with duodenal/pancreatic territories. The study purpose is to describe the angiographic anatomy of 3&9As and discuss their relevance when performing radioembolization (RE) of liver malignancies.Materials and MethodsThe anatomy of the 3&9As was systematically investigated by a retrospective analysis of angiograms, technetium Tc-99 m-macroaggregated albumin (MAA) scintigrams, yttrium-90 (Y90) Bremsstrahlung-SPECT/CT datasets, and clinical data of 153 patients who underwent RE between 2010 and 2013.ResultsAnalysis of preprocedural angiograms identified 3&9As in 36 (24%) of the 153 patients. Following embolization of the gastroduodenal artery, 3&9As were seen in 53 cases (35%). The three most common origins of the 3&9As were the right hepatic artery (n = 14), the cystic artery (n = 11), and S5 and S6 segmental arteries (n = 5 each). Extrahepatic Tc-99 m-MAA deposition in the territory of the 3&9As was significantly more frequent when 3&9As were detectable on preprocedural angiograms (28%{sub visible} vs. 11%{sub not} {sub visible}; p = 0.001) and especially when the 3&9As were not embolized or bridged prior to RE (50%{sub not} {sub occluded/bridged} vs. 19%{sub occupied/bridged}; p = 0.043). The presence of extrahepatic Y90 Bremsstrahlung after RE (n = 17) was attributable to microsphere diversion via the 3&9A territory in four patients and possible diversion via this territory in nine patients. Five of these 13 patients presented with epigastric pain, nausea, or vomiting (CTCAE severity grade ≤ 3) (p = 0.014).Conclusion3&9As are commonly detectable during evaluation angiography prior to RE, have a variable angioanatomic origin, and should be prophylactically occluded to prevent complications.
62 RADIOLOGY AND NUCLEAR MEDICINE↗
TNF-α induces expression of the circadian clock gene Bmal1 via dual calcium-dependent pathways in rheumatoid synovial cells
Highlights: • TNF-α induces over-expression of Bmal1 in rheumatoid synovial cells. • This over-expression was induced through dual calcium dependent pathways. • These dual pathways were regulated by p300/CBP histone acetyltransferases. • Ca{sup 2+} influx-p300/CBP pathway may provide a novel therapeutic strategy for RA. Tumor necrosis factor (TNF)-α is responsible for expressions of several clock genes and affects joint symptoms of rheumatoid arthritis (RA) with diurnal fluctuation. We tried to determine the mechanism involved in over-expression of Bmal1, induced by TNF-α, in primary cultured rheumatoid synovial cells. Cells were incubated with intra-cellular Ca{sup 2+} chelator BAPTA-AM, calcineurin inhibitor FK506 and p300/CBP (CREB binding protein) inhibitor C646, respectively, or transfected with p300 and CBP small interfering RNA (siRNA) before stimulation with TNF-α. Oscillation phase and amplitude of Bmal1, transcriptional activator Rorα, transcriptional repressor Rev-erbα, and histone acetyltransferases (p300 and Cbp) were evaluated by quantitative real-time PCR. As results, TNF-α did not influence the oscillation phase of Rev-erbα, while enhanced those of Rorα, resulting in over-expression of Bmal1. When Ca{sup 2+} influx was inhibited by BAPTA-AM, TNF-α-mediated up-regulation of Rorα was cancelled, however, that of Bmal1 was still apparent. When we further explored another pathway between TNF-α and Bmal1, TNF-α suppressed the expression of Rev-erbα in the absence of Ca{sup 2+} influx, as well as those of p300 and Cbp genes. Finally, actions of TNF-α, in increasing Bmal1/Rorα and decreasing Rev-erbα, were cancelled by C646 treatment or silencing of both p300 and Cbp. In conclusion, we determined a novel role of TNF-α in inducing Bmal1 via dual calcium dependent pathways; Rorα was up-regulated in the presence of Ca{sup 2+} influx and Rev-erbα was down-regulated in the absence of that. Results proposed that inhibition of p300/CBP could be new therapeutic targets for RA.
60 APPLIED LIFE SCIENCES↗
Knocking down clock control gene CRY1 decreases adipogenesis via canonical Wnt/β-catenin signaling pathway
Highlights: • Adipogenic differentiation induces CRY1 expression. . • Knockdown of CRY1 inhibits adipogenic differentiation and adipogenesis-specific gene expression. • Knockdown of CRY1 activates canonical Wnt/β-catenin signaling pathway. Cryptochrome gene 1(CRY1) is a member of circadian clock genes, which play an important role in adipocyte biology. CRY1 was reported to be related with the lipid metabolism, but the molecule mechanism of CRY1 in regulating the adipogenesis remains unclear. Here we report that CRY1 is a key regulator in adipogenic differentiation. We found that the expression levels of CRY1 in 3T3-L1 cells and C3H10T1/2 cells gradually increased during the process of adipogenic differentiation. Knockdown of endogenous CRY1 significantly inhibited the expression of adipogenic markers and lipid droplet formation in cells under adipogenic induction. In addition, knockdown of endogenous CRY1 promoted the expression and nuclear accumulation of β-catenin, the critical signal molecular in the canonical canonical Wnt signaling pathway, suggesting the regulation effect of CRY1 in adipogenesis was mediated by canonical Wnt/β-catenin signaling. Taken together, our study suggests that CRY1 regulates adipogenic differentiation through modulating the canonical Wnt/β-catenin signaling pathway.
60 APPLIED LIFE SCIENCES↗
Structures of the intermediates of Kok’s photosynthetic water oxidation clock
Inspired by the period-four oscillation in flash-induced oxygen evolution of photosystem II discovered by Joliot in 1969, Kok performed additional experiments and proposed a five-state kinetic model for photosynthetic oxygen evolution, known as Kok’s S-state clock or cycle. The model comprises four (meta)stable intermediates (S 0 , S 1 , S 2 and S 3 ) and one transient S 4 state, which precedes dioxygen formation occurring in a concerted reaction from two water-derived oxygens bound at an oxo-bridged tetra manganese calcium (Mn 4 CaO 5 ) cluster in the oxygen-evolving complex. This reaction is coupled to the two-step reduction and protonation of the mobile plastoquinone QB at the acceptor side of PSII. Here in this paper, using serial femtosecond X-ray crystallography and simultaneous X-ray emission spectroscopy with multi-flash visible laser excitation at room temperature, we visualize all (meta)stable states of Kok’s cycle as high-resolution structures (2.04–2.08 Å). In addition, we report structures of two transient states at 150 and 400 µs, revealing notable structural changes including the binding of one additional ‘water’, Ox, during the S 2 →S 3 state transition. Our results suggest that one water ligand to calcium (W3) is directly involved in substrate delivery. The binding of the additional oxygen Ox in the S 3 state between Ca and Mn1 supports O–O bond formation mechanisms involving O5 as one substrate, where Ox is either the other substrate oxygen or is perfectly positioned to refill the O5 position during O 2 release. Thus, our results exclude peroxo-bond formation in the S 3 state, and the nucleophilic attack of W3 onto W2 is unlikely.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗