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Fundamental differences between perception and cognition argue that the distinction can be maintained independently of cognitive penetrability. The core processes of cognition can be integrated under the theory of relational knowledge. The distinguishing properties include symbols and an operating system, structure-consistent mapping between representations, construction of representations in working memory that enable generation of inferences, and different developmental time courses.
We report the analysis of 154 hours of nearly continuous high-speed photometric data on the pulsating DB white dwarf (DBV) GD 358 obtained during the Whole Earth Telescope (WET) run of May 1990. The Fourier transform (FT) of the light curve is dominated by power in the range from 1200 – 1700μHz with more than 180 significant peaks in the total transform. We also see significant power at the sums and differences of the dominant frequencies, indicating the importance of nonlinear behavior. We can use this data to obtain an accurate total stellar mass, and surface He layer mass. The implied surface He layer mass, if correct, provides a significant and surprising challenge to stellar evolution theory, as well as the theory of chemical mixing.
White dwarf stars provide important boundary conditions for the understanding of stellar evolution. An adequate understanding of even these simple stars is impossible without detailed knowledge of their interiors. PG1346+082, an interacting binary white dwarf system, provides a unique opportunity to view the interior of one degenerate as it is brought to light in the accretion disk of the second star as the primary strips material from its less massive companion (see Wood et at. 1987).
PG1346+082 is a photometric variable with a four magnitude variation over a four to five day quasi-period. A fast Fourier transform (FFT) of the light curve shows a complex, time-dependent structure of harmonics. PG1346+082 exhibits flickering – the signature of mass transfer. The optical spectra of the system contain weak emission features during minimum and broad absorption at all other times. This could be attributed to pressure broadening in the atmosphere of a compact object, or to a combination of pressure broadening and doppler broadening in a disk surrounding the compact accretor. No hydrogen lines are observed and the spectra are dominated by neutral helium. The spectra also display variable asymmetric line profiles.
The recent upgrade of the Arecibo planetary radar system, combined with the huge increase in the near-Earth asteroid (NEA) discovery rate by large survey programs, has greatly increased our ability to observe these objects with radar. Radar provides size, shape, rotation, and trajectory information, and in most cases is the only ground-based technique that spatially resolves near-Earth objects. While the resolution of radar images (typically 7.5m) is not as high as for the very best spacecraft images, spacecraft can visit only a few such objects, and radar observations greatly increase our understanding of the diversity of near-Earth objects, at orders of magnitude lower cost. The single clearest result of these observations is the great variety of near-Earth objects, with binary systems, very fast and very slow rotations, spheres, “bifurcated” objects, and “shards”, suggesting that a similar variety of production and delivery mechanisms deliver these objects to near-Earth orbit. Spacecraft mission planning should take into account this variety, and concentrate on broad coverage of a wide range of objects.
Influenza A (H1N1) pdm09 became the predominant circulating strain in the United States during the 2013–2014 influenza season. Little is known about the epidemiology of severe influenza during this season.
A retrospective cohort study of severely ill patients with influenza infection in intensive care units in 33 US hospitals from September 1, 2013, through April 1, 2014, was conducted to determine risk factors for mortality present on intensive care unit admission and to describe patient characteristics, spectrum of disease, management, and outcomes.
A total of 444 adults and 63 children were admitted to an intensive care unit in a study hospital; 93 adults (20.9%) and 4 children (6.3%) died. By logistic regression analysis, the following factors were significantly associated with mortality among adult patients: older age (>65 years, odds ratio, 3.1 [95% CI, 1.4–6.9], P=.006 and 50–64 years, 2.5 [1.3–4.9], P=.007; reference age 18–49 years), male sex (1.9 [1.1–3.3], P=.031), history of malignant tumor with chemotherapy administered within the prior 6 months (12.1 [3.9–37.0], P<.001), and a higher Sequential Organ Failure Assessment score (for each increase by 1 in score, 1.3 [1.2–1.4], P<.001).
Risk factors for death among US patients with severe influenza during the 2013–2014 season, when influenza A (H1N1) pdm09 was the predominant circulating strain type, shifted in the first postpandemic season in which it predominated toward those of a more typical epidemic influenza season.
Infect. Control Hosp. Epidemiol. 2015;36(11):1251–1260
Perhaps no American novel has cut businessmen so unremittingly as Sinclair Lewis' Babbitt. Yet at the time of its appearance in 1922 reactions were surprisingly mixed. As an introduction to the persistence of “Babbittry” in the United States — in. life as in the lexicon of invective — the passions aroused during the first decade of “George Babbitt's” life bear review.
(Ni75Fe25)v/(SiO2)1-v nanocomposites with v =0.5, 0.7, and 1.0, where 75 denotes the atomic percent of Ni in the Ni-Fe alloy phase and v denotes the volume fraction of the magnetic constituent in the composite, were synthesized using a wet chemical approach. The x-ray diffraction and TEM experiments show that the synthetic NiFe/SiO2 is a two-phase composite system in that an amorphous insulating SiO2 layer coats each Ni-Fe particle. The Ni-Fe particle is in a fcc Ni-Fe alloy state. Its size can be controlled over a rather large range between 5 nm to 70 nm by adjusting the reaction parameters. Particular attention was paid to reduce the chemical reaction temperature so as to insure the smallness of the particle size. Meanwhile, measurements of the saturation magnetization indicated that the higher the heat treatment temperature, the more complete the chemical reaction to form the Ni-Fe alloys from precursor materials.
In an effort to explore new highly resistive soft magnetic materials, Fe/SiO2 nanocomposite materials have been synthesized using a wet chemical reaction approach in which the precursor complex was annealed at various temperatures. The crystallographic structure, nanostructure, morphology, and magnetic properties of the synthetic Fe/SiO2 particles were studied by x-ray diffraction, transmission electron microscopy, and magnetic measurements. The experimental results show that for this approach, the [.alpha]-Fe particles are coated with amorphous silica. The progress of the reaction, the purity of Fe/SiO2 in the synthetic powder, and the Fe particle size are highly dependent on the annealing temperature. By adjusting the annealing temperature, the particle size can be controlled from approximately 20 nm to 70 nm. For the synthetic nanopowder obtained by H2 reduction at 400 °C, there exists a superparamagnetic behavior below room temperature; while for the nanopowders obtained by reduction at higher temperatures, the ferromagnetic behavior is dominant. Based on these studies, optimum synthesis conditions for Fe/SiO2 nanocomposites is determined.
NiFe2O4 is an important high frequency soft magnetic material due to its ultra high resistivity; however, its initial permeability is rather low. Conventional magnetic ferrites are manufactured through ceramic processing. In an effort to explore innovative approaches for fabricating ferrite materials with improved performance, a study of fabricating nanostructured NiFe2O4 using wet chemical approaches has been carried out. The synthetic NiFe2O4 precursor was synthesized by a citrate reaction method followed by calcinating at various temperatures. Systematic studies concerning the crystallographic structure, the nanostructure and morphology of the particle, the phase homogeneity, the conditions for chemical reaction completion, and the magnetic properties have been carried out using x-ray diffraction, transmission electron microscopy, and magnetic measurements. The results show that by using a citrate reaction approach, pure phase and stoichiometric NiFe2O4 can be fabricated easily, and the particle size can be controlled on a nanometer scale, even at high calcination temperatures. In addition, a comparative study of the NiFe2O4 fabricated by conventional ceramic processing and this new citrate processing will be presented.
We report low and high field vibrating sample magnetometry results and resistance measurements on a highly oriented, single-phase sample of Y1Ba2Cu3O7−x. We find no anisotropy for the low-field (1mT) Meissner effect or trapped flux. Ratios for high field (to 1.9 T) and ρab/ρc are ∼ 2 and 3.6 respectively. Both are different from single-crystal results, a difference we attribute to grain boundary effects.
Hydrogenated amorphous silicon (a-Si:H) films prepared by electron cyclotron resonance plasma enhanced CVD (ECR PECVD) were investigated electrically and optically. The electrical and optical properties of a-Si:H were strongly dependent on magnet coil current, microwave power, and substrate temperature. A high deposition rate of a-Si:H up to 150 nm/min was realized by this technology. The photoconductive characteristics prepared at 300°C are comparable to those obtained by glow discharge PECVD (GD PECVD).
Total energy calculations for Ni-rich ß′-phase NiAl have been performed using the large system multiple scattering (LSMS) method. The large samples used to model the alloys involved up to 128 atoms per cell, and were constructed to have the experimental short range order (SRO) parameters. Both short range ordering and charge transfer effects are automatically taken into account in the calculation. The calculated formation energies of both stoichiometric and non-stoichiometric compounds are in excellent agreement with experiment.
A project to begin to address the phenomena of flow and element migration in fractured porous rock has recently been started by the Los Alamos National Laboratory, Sandia National Laboratories, and Argonne National Laboratory. The work has three objectives: 1) to develop the experimental, instrumental, and safety techniques necessary to conduct controlled, small-scale, radionuclide migration, field experiments; 2) to use these techniques to define radionuclide migration through rock by performing generic, at-depth experiments under closely controlled conditions in a single fracture in porous rock; and 3) to determine whether available lithologic, geochemical, and hydraulic properties together with existing or developed transport models are sufficient and appropriate to describe real field conditions (i.e., to scale from small-scale laboratory studies to bench-size studies to field studies). The detailed scope of this project and its current status are described.
A technique has been developed using 222Rn as a flow path monitor. Its principle advantage over other radiotracers or dyes is that while the Kd of Rn gas in water solution is zero and hence follows the water path, its 210Pb daughter is retained strongly by rock. The immobilized 210Pb is not subject to diffusion, an important consideration in the proposed Nevada Field Test. To evaluate the technique, a series of laboratory scale experiments have been performed. Artificial fissures consisting of glass plates and prepared flat surfaces were coupled to insure well characterized fissures. Water solutions of radiotracer were metered through these fissures and the discharge monitored to produce breakthrough curves as a function of flow rate. The rock surfaces were analysed for radionuclide concentration and the rock sectioned for diffusion profile into the rock.
Consolidation of nanostructure magnetic particles is required not only for manufacturing bulk component, it is actually a fundamental requirement for obtaining novel magnetic properties from the material. Consolidation (assembly) of nanoparticles to full density without deteriorating their nanostructure (size and morphology) is a big challenge. Here we present the consolidation experiments of NiFe/SiO2 and Co/SiO2 nanocomposites via detonation consolidation. This approach is based on the explosive pressure created when an acetylene and oxygen mixture gas fires in a sample containing tube, the very high hypersonic propulsion force makes nanoparticles deposit onto the target. Depending on the powder morphology and operation conditions, the density of the consolidated sample can reach over 91% of the theoretical density of the bulk materials. X-ray diffraction experiments on the samples before and after consolidation indicate that the denotation consolidations can be optimized such that it does not cause any phase transition. However, a particle size increase was observed. Static magnetic studies carried out on the samples before and after detonation operation shows that the saturation magnetization does not. This indicates that the operation does not cause an oxidation of the nanopowders. These experiments show that detonation approach is a good candidate for consolidating magnetic nanoparticles.
Conditions for the transfer printing of patterned carbon nanotube (CNT) films, along with a Au-gate, a poly methylmethacrylate (PMMA) dielectric layer and Au source-drain electrodes have been developed for the fabrication of thin-film transistors on a polyethylene terephthalate (PET) substrate. Chemical vapor deposition (CVD) grown CNTs were patterned using a photolithographic method.
Transfer printing was used to fabricate devices having both top gate and bottom gate configurations. Replacement of the SiO2 dielectric with PMMA correlates with a decreased hysteresis in the transconductance behavior. Encapsulation of the CNTs between the polymeric substrate and dielectric layer yields ambipolar behavior. Variations in device performance are also observed as a function of CNT film density and channel length, suggesting changing contributions of the metallic and semiconducting CNTs to the transport mechanism.
By alternating the gate voltage polarity of a pentacene thin film transistor, we show that the drain current is stabilized and thus the bias stress effect is overcome. This allows for controlled testing of the device sensitivity to environmental conditions. We find that the conductivity of the device decreases on the time scale of seconds when the device is exposed to water vapor, which is manifested through a decrease in mobility and a shift in the threshold voltage. Simple recombination modeling suggests that trapping is the responsible mechanism. However, the effects of water vapor can be reversed by exposing the device to dry nitrogen flow. The time scale for recovery is on the order of 10s of minutes.