321 research outputs found
Analysis, design, fabrication and testing of an optical tip clearance sensor
Analyses and the design, fabrication, and testing of an optical tip clearance sensor with intended application in aircraft propulsion control systems are reported. The design of a sensor test rig, evaluation of optical sensor components at elevated temperatures, sensor design principles, sensor test results at room temperature, and estimations of sensor accuracy at temperatures of an aircraft engine environment are discussed. Room temperature testing indicated possible measurement accuracies of less than 12.7 microns (0.5 mils). Ways to improve performance at engine operating temperatures are recommended. The potential of this tip clearance sensor is assessed
Mars riometer system
A riometer (relative ionospheric opacity meter) measures
the intensity of cosmic radio noise at the surface of a planet.
When an electromagnetic wave passes through the
ionosphere collisions between charged particles (usually
electrons) and neutral gases remove energy from the wave.
By measuring the received signal intensity at the planet's
surface and comparing it to the expected value (the quietday
curve) a riometer can deduce the absorption
(attenuation) of the trans-ionospheric signal. Thus the
absorption measurements provide an indication of ionisation
changes occurring in the ionosphere.
To avoid the need for orbiting sounders riometers use the
cosmic noise background as a signal source. Earth-based
systems are not subject to the challenging power, volume
and mass restriction that would apply to a riometer for
Mars. Some Earth-based riometers utilise phased-array
antennas in order to provide an imaging capability.UnpublishedVienna - Austria3.9. Fisica della magnetosfera, ionosfera e meteorologia spazialeope
Semiclassical mechanics of a non-integrable spin cluster
We study detailed classical-quantum correspondence for a cluster system of
three spins with single-axis anisotropic exchange coupling. With autoregressive
spectral estimation, we find oscillating terms in the quantum density of states
caused by classical periodic orbits: in the slowly varying part of the density
of states we see signs of nontrivial topology changes happening to the energy
surface as the energy is varied. Also, we can explain the hierarchy of quantum
energy levels near the ferromagnetic and antiferromagnetic states with EKB
quantization to explain large structures and tunneling to explain small
structures.Comment: 9 pages. For related works see
"http://www.msc.cornell.edu/~clh/clh.html
Research on the relation of EEG signal chaos characteristics with high-level intelligence activity of human brain
Using phase space reconstruct technique from one-dimensional and multi-dimensional time series and the quantitative criterion rule of system chaos, and combining the neural network; analyses, computations and sort are conducted on electroencephalogram (EEG) signals of five kinds of human consciousness activities (relaxation, mental arithmetic of multiplication, mental composition of a letter, visualizing a 3-dimensional object being revolved about an axis, and visualizing numbers being written or erased on a blackboard). Through comparative studies on the determinacy, the phase graph, the power spectra, the approximate entropy, the correlation dimension and the Lyapunov exponent of EEG signals of 5 kinds of consciousness activities, the following conclusions are shown: (1) The statistic results of the deterministic computation indicate that chaos characteristic may lie in human consciousness activities, and central tendency measure (CTM) is consistent with phase graph, so it can be used as a division way of EEG attractor. (2) The analyses of power spectra show that ideology of single subject is almost identical but the frequency channels of different consciousness activities have slight difference. (3) The approximate entropy between different subjects exist discrepancy. Under the same conditions, the larger the approximate entropy of subject is, the better the subject's innovation is. (4) The results of the correlation dimension and the Lyapunov exponent indicate that activities of human brain exist in attractors with fractional dimensions. (5) Nonlinear quantitative criterion rule, which unites the neural network, can classify different kinds of consciousness activities well. In this paper, the results of classification indicate that the consciousness activity of arithmetic has better differentiation degree than that of abstract
Poboljšana elektromagnetska kompatibilnost (EMC) sklopnog energetskog pretvarača sa slučajnom modulacijom
This paper surveys some analytical and experimental results concerning different randomized modulation strategies in switched-mode power converters (SMPCs). After a short review of practical experiences within the literature it presents the benefits of several randomized schemes for power converters (i.e. reduced electromagnetic interference - EMI, and lower acoustic noise). It also introduces the mathematical background for dealing with randomized modulation within the medium-frequency range: power spectrum density (PSD). Finally, the EMI measurements confirm the improved EMC performances of the randomized boost rectifier, as also in the DC-DC buck converter.Ovaj članak istražuje analitičke i eksperimentalne rezultate različitih slučajnih strategija modulacije u sklopnim energetskim pretvaračima (SMPCs). Nakon kratkog pregleda praktičnih iskustava iz literature, predstavljene su prednosti nekoliko slučajnih shema za energetske pretvarače (smanjena elektromagnetska interferencija - EMI, i niži akustični šum). Također, uvedena je matematička podloga za rad sa slučajnom modulacijom u području srednjih frekvencija: spektralna gustoća snage (PSD). Konačno, EMI mjerenja potvrđuju poboljšanja EMC performansi slučajnih uzlaznih ispravljača, kao i DC-DC silaznih pretvarača
Inhibition of Multidrug Resistance by SV40 Pseudovirion Delivery of an Antigene Peptide Nucleic Acid (PNA) in Cultured Cells
Peptide nucleic acid (PNA) is known to bind with extraordinarily high affinity and sequence-specificity to complementary nucleic acid sequences and can be used to suppress gene expression. However, effective delivery into cells is a major obstacle to the development of PNA for gene therapy applications. Here, we present a novel method for the in vitro delivery of antigene PNA to cells. By using a nucleocapsid protein derived from Simian virus 40, we have been able to package PNA into pseudovirions, facilitating the delivery of the packaged PNA into cells. We demonstrate that this system can be used effectively to suppress gene expression associated with multidrug resistance in cancer cells, as shown by RT-PCR, flow cytometry, Western blotting, and cell viability under chemotherapy. The combination of PNA with the SV40-based delivery system is a method for suppressing a gene of interest that could be broadly applied to numerous targets
Behavioural Significance of Cerebellar Modules
A key organisational feature of the cerebellum is its division into a series of cerebellar modules. Each module is defined by its climbing input originating from a well-defined region of the inferior olive, which targets one or more longitudinal zones of Purkinje cells within the cerebellar cortex. In turn, Purkinje cells within each zone project to specific regions of the cerebellar and vestibular nuclei. While much is known about the neuronal wiring of individual cerebellar modules, their behavioural significance remains poorly understood. Here, we briefly review some recent data on the functional role of three different cerebellar modules: the vermal A module, the paravermal C2 module and the lateral D2 module. The available evidence suggests that these modules have some differences in function: the A module is concerned with balance and the postural base for voluntary movements, the C2 module is concerned more with limb control and the D2 module is involved in predicting target motion in visually guided movements. However, these are not likely to be the only functions of these modules and the A and C2 modules are also both concerned with eye and head movements, suggesting that individual cerebellar modules do not necessarily have distinct functions in motor control
Dispersion of the second-order nonlinear susceptibility in ZnTe, ZnSe, and ZnS
We have measured the absolute values of the second-harmonic generation (SHG) coefficient |d| for the zinc-blende II-VI semiconductors ZnTe, ZnSe, and ZnS at room temperature. The investigated spectral region of the fundamental radiation λF ranges from 520 to 1321 nm using various pulsed laser sources. In the transparent region of the II-VI semiconductors, the SHG coefficient exceeds the values of birefringent materials as ammonium dihydrogen phosphate (ADP) and potassium dihydrogen phosphate (KDP) by one or two orders of magnitudes. Above the E0 band gap a strong dispersion of |d| is observed, showing a maximum for a second-harmonic frequency close to the E1 gap. The experimental results are compared to calculated values using a simple three-band model including spin-orbit splitting. Substantial agreement is found to the experimentally observed dispersion of the second-order nonlinear susceptibility
Deletion of individual Ku subunits in mice causes an NHEJ-independent phenotype potentially by altering apurinic/apyrimidinic site repair
Ku70 and Ku80 form a heterodimer called Ku that forms a holoenzyme with DNA dependent-protein kinase catalytic subunit (DNA-PKCS) to repair DNA double strand breaks (DSBs) through the nonhomologous end joining (NHEJ) pathway. As expected mutating these genes in mice caused a similar DSB repair-defective phenotype. However, ku70-/- cells and ku80 -/- cells also appeared to have a defect in base excision repair (BER). BER corrects base lesions, apurinic/apyrimidinic (AP) sites and single stand breaks (SSBs) utilizing a variety of proteins including glycosylases, AP endonuclease 1 (APE1) and DNA Polymerase β (Pol β). In addition, deleting Ku70 was not equivalent to deleting Ku80 in cells and mice. Therefore, we hypothesized that free Ku70 (not bound to Ku80) and/or free Ku80 (not bound to Ku70) possessed activity that influenced BER. To further test this hypothesis we performed two general sets of experiments. The first set showed that deleting either Ku70 or Ku80 caused an NHEJ-independent defect. We found ku80-/- mice had a shorter life span than dna-pkcs-/- mice demonstrating a phenotype that was greater than deleting the holoenzyme. We also found Ku70-deletion induced a p53 response that reduced the level of small mutations in the brain suggesting defective BER. We further confirmed that Ku80-deletion impaired BER via a mechanism that was not epistatic to Pol β. The second set of experiments showed that free Ku70 and free Ku80 could influence BER. We observed that deletion of either Ku70 or Ku80, but not both, increased sensitivity of cells to CRT0044876 (CRT), an agent that interferes with APE1. In addition, free Ku70 and free Ku80 bound to AP sites and in the case of Ku70 inhibited APE1 activity. These observations support a novel role for free Ku70 and free Ku80 in altering BER. © 2014 Choi et al
3 years of liraglutide versus placebo for type 2 diabetes risk reduction and weight management in individuals with prediabetes: a randomised, double-blind trial
Background Liraglutide 3\ub70 mg was shown to reduce bodyweight and improve glucose metabolism after the 56-week period of this trial, one of four trials in the SCALE programme. In the 3-year assessment of the SCALE Obesity and Prediabetes trial we aimed to evaluate the proportion of individuals with prediabetes who were diagnosed with type 2 diabetes. Methods In this randomised, double-blind, placebo-controlled trial, adults with prediabetes and a body-mass index of at least 30 kg/m2, or at least 27 kg/m2 with comorbidities, were randomised 2:1, using a telephone or web-based system, to once-daily subcutaneous liraglutide 3\ub70 mg or matched placebo, as an adjunct to a reduced-calorie diet and increased physical activity. Time to diabetes onset by 160 weeks was the primary outcome, evaluated in all randomised treated individuals with at least one post-baseline assessment. The trial was conducted at 191 clinical research sites in 27 countries and is registered with ClinicalTrials.gov, number NCT01272219. Findings The study ran between June 1, 2011, and March 2, 2015. We randomly assigned 2254 patients to receive liraglutide (n=1505) or placebo (n=749). 1128 (50%) participants completed the study up to week 160, after withdrawal of 714 (47%) participants in the liraglutide group and 412 (55%) participants in the placebo group. By week 160, 26 (2%) of 1472 individuals in the liraglutide group versus 46 (6%) of 738 in the placebo group were diagnosed with diabetes while on treatment. The mean time from randomisation to diagnosis was 99 (SD 47) weeks for the 26 individuals in the liraglutide group versus 87 (47) weeks for the 46 individuals in the placebo group. Taking the different diagnosis frequencies between the treatment groups into account, the time to onset of diabetes over 160 weeks among all randomised individuals was 2\ub77 times longer with liraglutide than with placebo (95% CI 1\ub79 to 3\ub79, p<0\ub70001), corresponding with a hazard ratio of 0\ub721 (95% CI 0\ub713\u20130\ub734). Liraglutide induced greater weight loss than placebo at week 160 (\u20136\ub71 [SD 7\ub73] vs 121\ub79% [6\ub73]; estimated treatment difference 124\ub73%, 95% CI 124\ub79 to 123\ub77, p<0\ub70001). Serious adverse events were reported by 227 (15%) of 1501 randomised treated individuals in the liraglutide group versus 96 (13%) of 747 individuals in the placebo group. Interpretation In this trial, we provide results for 3 years of treatment, with the limitation that withdrawn individuals were not followed up after discontinuation. Liraglutide 3\ub70 mg might provide health benefits in terms of reduced risk of diabetes in individuals with obesity and prediabetes. Funding Novo Nordisk, Denmark
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