To send content items to your account,
please confirm that you agree to abide by our usage policies.
If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account.
Find out more about sending content to .
To send content items to your Kindle, first ensure firstname.lastname@example.org
is added to your Approved Personal Document E-mail List under your Personal Document Settings
on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part
of your Kindle email address below.
Find out more about sending to your Kindle.
Note you can select to send to either the @free.kindle.com or @kindle.com variations.
‘@free.kindle.com’ emails are free but can only be sent to your device when it is connected to wi-fi.
‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
Stellarator configurations with reactor relevant energetic particle losses are constructed by simultaneously optimizing for quasisymmetry and an analytically derived metric (
), which attempts to align contours of the second adiabatic invariant,
with magnetic surfaces. Results show that with this optimization scheme it is possible to generate quasihelically symmetric equilibria on the scale of ARIES-CS which completely eliminate all collisionless alpha particle losses within normalized radius
. We show that the best performance is obtained by reducing losses at the trapped–passing boundary. Energetic particle transport can be improved even when neoclassical transport, as calculated using the metric
, is degraded. Several quasihelically symmetric equilibria with different aspect ratios are presented, all with excellent energetic particle confinement.
Flaviviruses include many viruses causing encephalitis, including West Nile encephalitis, St. Louis encephalitis, tick-borne encephalitis and Japanese encephalitis. Human pegivirus genotype-1 (HPgV-1) is a lesser known member of the Flaviviridae family and has been identified in human serum, cerebrospinal fluid and brain tissue. Here, we describe two adult patients with fatal HPgV-1-associated encephalitis. Neuroimaging revealed multifocal lesions, initially present in the periventricular and brain stem white matter, then one year later throughout the corona radiata bilaterally with marked involvement of the brainstem and cervical spinal cord. Phylogenetic analyses of HPgV-1 showed clustering of brain-derived sequences from both patients with other human pegiviruses. In both patients, a novel 87-nucleotide deletion in the viral NS2 gene was detected. The presence of positive and negative strand HPgV-1 RNA and viral antigens in both patients indicated viral persistence and replication in the CNS. Autopsy showed lymphocyte infiltration and gliosis predominantly in white matter of the brain and brain stem but, to a lesser extent, also in grey matter. Immunofluorescence revealed HPgV-1 NS5A antigen in lymphocytes as well as in astrocytes and oligodendrocytes. Thus, we hypothesize that the novel deletion in the NS2 coding region may have caused HPgV-1 neuroadaptation or might represent a yet unrecognized genotype of human pegivirus.
This presentation will enable the learner to:
1.Describe the clinical and neuropathological features of fatal human pegivirus-associated encephalitis
2.Recognize the importance of molecular analysis in encephalitis cases with unknown etiology
In order to ensure the quality of the source catalogue derived from the SASS processing an automatic as well as a visual screening procedure was applied to 1378 survey fields. Most (94%) of the 18,811 sources were confirmed by this screening process. The rest is flagged for various reasons. Broad band images are available for a subset of the flagged sources. Details of the screening process can be found at www.rosat.mpe-garching.mpg.de/survey/rass-bsc/doc.html.
Following the recent evidence for the presence of an excess of power around 1 mHz in the frequency spectrum of the Doppler shift measurements for Procyon (Martic et al., 1999), we searched for individual frequencies of p-modes from three independent observing runs (5, 10 and 15 nights). All observations (December 1997, November 1998, January 1999) were made with the ELODIE spectrograph on the 1.93 m telescope at Observatoire de Haute Provence. The individual peaks in cleaned power spectra of each time series in the interval of excess power are compared with the predicted p-mode frequencies from stellar models (Chaboyer et al., 1999) for Procyon A.
We present a series of statistical tests using homogeneous data and measurements for a sample of Seyfert galaxies. These galaxies were selected from mostly isotropic properties, their far infrared fluxes and warm infrared colors, which provide a considerable advantage over the criteria used by most investigators in the past, like ultraviolet excess. Our results provide strong support for a Unified Model in which Seyferts 2’s contain a torus seen more edge-on than in Seyferts l’s and show that previous results showing the opposite were most likely due to selection effects.
The aim of this paper (further developed in Barban et al. 1999) is to present new evidence of the possible stellar origin of the observed excess power in the power spectrum of Procyon A presented in Martic et al. (1999) by comparing these observational data with theoretical predictions and numerical simulations.
We have observed Procyon with the fiber-fed échelle spectrograph ELODIE coupled with a Fabry-Perot etalon at the 193-cm of the Observatoire de Haute Provence (France) over 5 nights during 1997 December – 1998 January. Here, we present the results of a search for solar-like oscillations on this star and the performance of this instrumentation for asteroseismology. The power spectra show an excess of signal between 0.42 mHz and 1.46 mHz, which could be due to stellar oscillations.
Dry etching of silver for the metallization in microelectronics is
investigated. Etching is performed using an electron-cyclotron-resonance
reactive-ion-beam-etching system (ECR-RIBE) in an Ar/CF4 or
Ar/CF4/O2 mixture. The etch characteristics are
strongly affected by ion energy (beam voltage and microwave energy); the
O2 concentration in the reactive mixture has only a small
effect. An anisotropic, smooth etch profile and clean surface are obtained.
Focused ion beam (FIB) and atomic force microscopy (AFM) have been used to
study the etched profile and the roughness, respectively.
The physical and electrical properties as well as thermal stability of
reactively sputtered titanium nitride (TiN) film serving as a diffusion
barrier was studied for silver (Ag) metallization. The thermal stability of
Ag/TiN metallizations on Si with 12-nm-thick TiN barriers, as-deposited and
after annealing at 300-650°C in N2/H2 for 30 min, was
investigated with sheet resistance measurement, X-ray diffraction, focused
ion beam-scanning electron microscopy, atomic force microscopy and X-ray
photoelectron spectroscopy. According to electrical measurement no change of
sheet resistance was found after annealing at 600°C, but an abrupt rise
appeared at 650°C annealing. There are two causes by which the Ag/TiN/Si
structure became degraded. One is agglomeration of the silver layer, and the
other is oxidation and diffusion which are also associated problems during
A novel, proprietary, and general approach to depositing thin films and coatings, The novel Jet Vapor Deposition TM (JVDTM) process is described, in which single or multiple “jets in low vacuum” are coupled with “mobile substrates” to generate a wide range of multicomponent, multilayer and “host-guest” thin films and coatings. Highly transparent and conducting aluminum-doped ZnO (ZnO:A1) thin films have been deposited at room temperature on glass slide, flexible polymer and thin film PV coated substrates by the JVDTM process. The thin films obtained from the optimized operating conditions have an average transmittance of about 85% in the visible range and electrical resistivities of 7 to 10×10-4 Ω-cm. Proper control of substrate bias, dopant content, deposition rate, and oxygen to metal ratio are the keys to depositing low resistivity and high transparency thin films.
Electrically switchable volume reflection holograms were written by inhomogeneous illumination of a prepolymer syrup containing a nematic liquid crystal and a multifunctional acrylate monomer. Switchable holograms are diffractive optics structures and the diffraction efficiency can be controlled by the application of an electric field. Reflection gratings with grating spacing varying between 0.16-0.27 µm were made during the phase separation of liquid crystals from the fast curing prepolymer syrup. The reflection efficiency of the holograms were electrically modulated with the applied field of ∼10-15V/µm. Real time study of the grating formation revealed that the maximum efficiency is reached in ∼15 seconds. The shrinkage of the host polymer during grating formation resulted in the blue shift of the reflection notch. The response time of the grating in an electric field is ∼50 µs. Low voltage scanning electron microscope studies showed the presence of discrete nematic droplet domains of sizes 30-60 nm in liquid crystal rich region.
As MOSFET dimensions are aggressively scaled, minimizing the thermal budget becomes critical for limiting the diffusion of channel profiles. Unfortunately, high quality dielectrics with low deposition temperatures have not been readily available. Typical room temperature dielectrics are porous and electrically leaky. A promising technique for low temperature dielectric deposition is Jet Vapor Deposition (JVD).  Two coaxial quartz nozzles spray the process gases to the substrate surface at super-sonic speeds while a microwave cavity generates a plasma in the nozzle.  We have successfully deposited silicon nitride films using SiH4/He and N2/He gas mixtures. These are the first reported JVD results on 200 mm wafers.
For white light generation with LUCOLEDs the phosphors on the base of YAG:Ce are ideally suited. The variation of the phosphor composition were performed. Powder Ga-substituted phosphors as well as Lu,Y,La,Sc- substituted epitaxial films were investigated. The effects on luminescence and excitation spectra, which is relevant for luminescence conversion, are reported.
This paper reviewed work to date on multicomponent oxides deposited, utilizing openatmosphere Combustion Chemical Vapor Deposition for electronic applications. Epitaxial barium strontium titanate and strontium titanate thin films were deposited on (100) MgO single crystal substrates. They were patterned to form interdigitated structures for electrically tunable devices, namely, coupled microstripline phase shifters (CMPS). The undoped, as-deposited perovskite dielectrics exhibited a figure of merit of 53°/dB at 20 GHz and 23°C, indicating high degree of tunability and fairly low loss. High-permittivity (ε=263), polycrystalline BST and SrTiO3 were studied for dynamic random access memory, and leakage current density of 10−7 A/cm2 was measured. Intended for non-volatile ferroelectric memory, lead zirconium titanate was deposited onto a seed layer of perovskite structure to prevent the growth of the unwanted pyrochlore phase. To function as buffer layers for superconductor applications, epitaxial CeO2, YSZ, SrTiO3, LaAlO3, Y2O3, and Yb2O3 coatings on single crystal and textured nickel substrate were investigated. Electronic analyses and characterization, using SEM, EDS, XRD, and X-ray pole figures, were presented.
Internal sequences of Tn501(Hg) and Tn721(Tc) have been compared by hybridization. In spite of the difference in the resistance they code for, there is extensive homology between the two elements. This homology resides in the transposon-coded genes that are necessary for transposition and indicates that the elements are closely related.
Tholins are polymeric hydrogenated carbon nitrides formed from N2:CH4 mixtures exposed to electrical discharges. They are complex disordered solids, and their structural chemistry and formation processes are not yet fully understood. Tholins have been widely adopted as useful analogs of reddish organic solids associated with planetary bodies or in interstellar space (e.g., Titan's aerosols, reddish surfaces of outer objects, interstellar organics, etc.) for fitting astronomical observations. However, there has been little evidence to date that they in fact constitute pertinent model materials, i. e. with chemical structure/composition similar to those presumed to be present in planetary or interstellar organic solids. In this contribution, we first review recent advances made regarding the determination of composition and structure of tholins produced in the laboratory. They point to a high chemical selectivity in the range of functional groups present, the control of unsaturation by nitrogen, and the highly disordered character of the structures. In a second section, we discuss the relationship between chemistry and the optical properties of tholins, and we point out the lack of a unique relationship between the shape and strength of the visible absorption bands and the chemical composition or structure of the model tholins. The tholins exhibit similarities with HCN “polymers”, that are suspected to be present in cometary refractory dust. This points to the existence of possible similar polymerisation processes, and it suggests they could also be used as analogs of N-rich cometary organics. Laboratory-based studies of cometary dust might offer new insights on the “chemical relevancy” of tholins, as combined micro-analytical techniques will allow direct comparison of chemical information between the materials produced. In a third section we present recent results pertaining to the search for such compounds in cometary grains (Stardust grains, interplanetary dust particles - IDPs). We show that some N-rich spots in stratospheric IDPs are rich in cyanide species, but no tholin-like compounds or polymeric HCN have been detected to date.
This article reviews the extant twin studies employing magnetic resonance imaging data (MRI), with an emphasis on studies of populationbased samples. There have been approximately 75 twin reports using MRI, with somewhat under half focusing on typical brain structure. Of these, most are samples of adults. For large brain regions such as lobar volumes, the heritabilities of large brain volumes are consistently high, with genetic factors accounting for at least half of the phenotypic variance. The role of genetics in generating individual differences in the volumes of small brain regions is less clear, mostly due to a dearth of information, but rarely because of disagreement between studies. Multivariate analyses show strong genetic relationships between brain regions. Cortical regions involved in language, executive function, and emotional regulation appear to be more heritable than other areas. Studies of brain shape also show significant, albeit lower, genetic effects on population variance. Finally, there is evidence of significant genetically mediated relationships between intelligence and brain structure. At present, the majority of twin imaging studies are limited by sample sizes small by the standards of behavioral genetics; nevertheless the literature at present represents a pioneering effort in the pursuit of answers to many challenging neurobiological questions.
Several large studies have demonstrated that the liability to smoke cigarettes is strongly genetically influenced. However, the role of genetic and environmental risk factors in the use of other common forms of tobacco use has yet to be studied. Data on the regular use of cigarettes, cigars, pipes, dip (moist snuff), and chewing tobacco from 2634 male twins were analyzed with ACE structural equation models. Twin similarity for regular cigarette and dip use was largely genetic in origin. However, twin resemblance for chewing tobacco was just about equally the result of genes and shared environment, and twin similarity for use of pipes and cigars was entirely the result of shared environmental factors. Thus, the genetic influences on the liability for regular tobacco use appear to vary based on tobacco type. The causes for the use of different forms of tobacco are complex and worthy of further study.