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Capillary collimators have found a number of uses in fluorescence, diffraction and other x-ray fields. Most of these applications are realized with single, straight glass capillaries. Focussing of synchrotron x-radiation beams has been shown with tapered capillaries. In addition, numerous straight and bent capillaries, bundled into lens-like optics, offer experimenters many other possibilities for better use of the x-radiation from tubes, synchrotron radiation, and plasma sources or the x-ray intensity collected from samples.
Previous studies of conduct disorder (CD) have reported structural and functional alterations in the limbic system. However, the white matter tracts that connect limbic regions have not been comprehensively studied. The uncinate fasciculus (UF), a tract connecting limbic to prefrontal regions, has been implicated in CD. However, CD-related alterations in other limbic tracts, such as the cingulum and the fornix, have not been investigated. Furthermore, few studies have examined the influence of sex and none have been adequately powered to test whether the relationship between CD and structural connectivity differs by sex. We examined whether adolescent males and females with CD exhibit differences in structural connectivity compared with typically developing controls.
We acquired diffusion-weighted magnetic resonance imaging data from 101 adolescents with CD (52 females) and 99 controls (50 females). Data were processed for deterministic spherical deconvolution tractography. Virtual dissections of the UF, the three subdivisions of the cingulum [retrosplenial cingulum (RSC), parahippocampal and subgenual cingulum], and the fornix were performed and measures of fractional anisotropy (FA) and hindrance-modulated orientational anisotropy (HMOA) were analysed.
The CD group had lower FA and HMOA in the right RSC tract relative to controls. Importantly, these effects were moderated by sex – males with CD significantly lower FA compared to male controls, whereas CD and control females did not differ.
Our results highlight the importance of considering sex when studying the neurobiological basis of CD. Sex differences in RSC connectivity may contribute to sex differences in the clinical presentation of CD.
Traits of attention-deficit/hyperactivity disorder (ADHD) and autism spectrum disorder (ASD) are strongly associated in children and adolescents, largely due to genetic factors. Less is known about the phenotypic and aetiological overlap between ADHD and ASD traits in adults.
We studied 6866 individuals aged 20–28 years from the Swedish Study of Young Adult Twins. Inattention (IA) and hyperactivity/impulsivity (HI) were assessed using the WHO Adult ADHD Self-Report Scale-V1.1. Repetitive and restricted behaviours (RRB) and social interaction and communication (SIC) were assessed using the Autism-Tics, ADHD, and other Comorbidities inventory. We used structural equation modelling to decompose covariance between these ADHD and ASD trait dimensions into genetic and shared/non-shared environmental components.
At the phenotypic level, IA was similarly correlated with RRB (r = 0.33; 95% Confidence Interval (CI) 0.31–0.36) and with SIC (r = 0.32; 95% CI 0.29–0.34), whereas HI was more strongly associated with RRB (r = 0.38; 95% CI 0.35–0.40) than with SIC (r = 0.24; 95% CI 0.21–0.26). Genetic and non-shared environmental effects accounted for similar proportions of the phenotypic correlations, whereas shared environmental effects were of minimal importance. The highest genetic correlation was between HI and RRB (r = 0.56; 95% 0.46–0.65), and the lowest was between HI and SIC (r = 0.33; 95% CI 0.23–0.43).
We found evidence for dimension-specific phenotypic and aetiological overlap between ADHD and ASD traits in adults. Future studies investigating mechanisms underlying comorbidity between ADHD and ASD may benefit from exploring several symptom-dimensions, rather than considering only broad diagnostic categories.
Background: Intracranial mycotic aneurysms are rare forms of vascular abnormalities. They are typically fragile and have high tendency to bleed. Even when they are successfully secured upon intervention, the medical management can be challenging in presence of other non-ruptured aneurysms and concomitant cerebral vasospasm. Methods: A 31 year old female was admitted with right sided large intracerebral hemorrhage due to ruptured mycotic MCA aneurysm. She was also known with severe tricuspid regurgitation from drug abuse. Others aneurysms were also located intracranially and extracranially, including subclavian and renal arteries. Results: The MCA aneurysm was successfully clipped during decompressive craniectomy. The non-ruptured left ACA aneurysm was occluded through endovascular intervention. Due to cardiac condition and presence of other non-secured extarcranial aneurysms, we followed the MNI protocol for treating cerebral vasospsam by milrinone infusion. The treatment was successful for over three weeks until another micro-aneurysm had ruptured which had lead to severe and rapid clinical deterioration, that had lead eventually to death. Conclusions: Intracranial mycotic aneurysms remain challenging. Patients should be selected for surgical clipping versus endovascular intervention based on clinical state and radiological features. We suggest using milrinone over induced hypertension therapy for post-intervention cerebral vasospasm in order to lower the risk for rupturing non-secured aneurysms.
An appreciation of the diversity of art library users and their information I needs, and of the literature of art, is a necessary prerequisite to consideration I of the objectives of cooperative collection development and resource sharing I among art libraries. The idea of cooperation gathered momentum after World I War 1, after it had become clear that no art library could ever be I comprehensive, and was put into practice after the Second World War, at I local and national levels. Local cooperative schemes were implemented at I Vienna and in Ohio State (ARLO); the Farmington Plan was by contrast an I example of a national programme. In the Federal Republic of Germany the I libraries belonging to the AKB operate a cooperative acquisitions scheme and I receive extra funding to allow them to specialise in particular subject areas in I addition to their normal acquisitions. The Fine Arts Library of Harvard I University participates in the Research Libraries Group Art and Architecture I Program. The concept of assigning different subjects and collection I responsibilities to different libraries in order to achieve comprehensive I coverage makes a lot of sense especially if in academic institutions links can be I developed between the library’s specialisation and the institution’s academic programme.
Approximately 6,000 current periodicals may be considered relevant to the art library, though no one art library can provide more than a fraction of these. Aids to the selection of an essential ‘core’ collection include specialized bibliographies; for access to periodicals outside its means or scope the art library must rely on cooperation with other libraries. Micro-publishing can play a vital part in facilitating global access. to art periodicals; meanwhile the art librariun can make a more informed selection of titles for a particular library, by analysing the needs of the library’s actual and potential users, and by studying what has been written on the history of art periodicals and of their usefulness. Excerpts from a paper presented to the ARLIS International Conference on art periodicals at the University of Sussex on April 9th.
As the range and sophistication of visual resources, and the size of collections available to the art historian and student have increased over the last century, so has the need for an appropriately qualified body of professionals to organise and develop them. This paper explains how and why those involved with visual resources have tended to have a background and training other than in librarianship, and how as a consequence, the two branches of the profession of art librarianship (textual and visual) have grown apart, with visual resources professionals allying themselves to art historical organisations. The author makes a case for the merging of the two professions, united in serving the same subject oriented clientele. This paper was first delivered to the Section of Art Libraries at the IFLA Council, in Montreal, August 1982.
Piezoelectric AlGaN/GaN FETs on SiC with high carrier mobility have been fabricated yielding IDS=450 mA/mm and gm=200 mS/mm. In the on-state, under UV-illumination, the devices sustain a drain voltage of VDS=49 V, corresponding to a power dissipation of 26.5 W/mm. On turn-on of the device from the pinch-off state, a significant delay in the drain current build-up is observed. This effect depends on the pinch-off time and the pinch-off voltage and can be removed by either a brief UV-illumination or a VDS>25 V applied in the on-state. The drain current transients are characterized by a relaxation time τ, which is in the order of several hundred seconds. From the temperature dependence of τ, an activation energy of about 280 meV and a capture cross section of 4.4·10−18cm2 were determined. The devices show pronounced persistent photoconductivity (PPC) and the drain current ID is sensitive to illumination.
Ochotonophila flava Dickoré & Freitag sp. nov. (Caryophyllaceae – Silenoideae) is described from the mountains of Bamiyan Province, central Afghanistan. It differs from the two previously known species endemic to Afghanistan, Ochotonophila allochrusoides Gilli and O. eglandulosa Hedge & Wendelbo, by its cream to yellow petals and elliptic leaves. A key to the identification of Ochotonophila species is provided; distribution and ecology are outlined.
We first present a recently developed three-dimensional chemodynamic code for galaxy evolution from the Kiev–Kiel collaboration. It follows the evolution of all components of a galaxy, such as dark matter, stars, molecular clouds and diffuse interstellar matter. Dark matter and stars are treated as collisionless N-body systems. The interstellar matter is numerically described by a smoothed particle hydrodynamics approach for the diffuse (hot) gas and a sticky particle scheme for the (cool) molecular clouds. Physical processes, such as star formation, stellar death, or condensation and evaporation processes of clouds interacting with the ISM are described locally. An example application of the model to a star forming dwarf galaxy will be shown for comparison with other codes. Secondly, we will discuss new kinds of exotic chemodynamic processes, as they occur in dense gas–star systems in galactic nuclei, such as non-standard ‘drag’-force interactions, destructive and gas-producing stellar collisions. Their implementation in one-dimensional dynamic models of galactic nuclei is presented. Future prospects to generalise these to three dimensions are in progress and will be discussed.
Single crystalline, ferroelectric BaTiO3 as material with the highest piezoelectric constants among the perovskites with ordered sublattices was implanted with 111In(111Cd). The electric field gradient at the Ti position was measured with perturbed γγ-angular correlation spectroscopy (PAC) while the crystal was exposed to an external electric field. A quadratic dependence could be observed: νQ(E) = (34.8(1) + 0.16(4) E/kV/mm + 0.080(2) E2/kV2/mm2) MHz. Point charge model calculations reproduce the linear change of Vzz, but not the quadratic term. The polarizability of the host ions of BaTiO3 is known to be nonlinear with respect to an electric field. The resulting quadratic shift of the electron density is reflected in the strength of the EFG.
Capillary optics appear to permit the fabrication of practical collimator systems for laserdriven x-ray point sources. With such collimators, the illumination of wafers can meet the tight requirements for lithographic patterning of sub-micron device structures. However, the use of x-radiation with photon energies between 800–1200 eV makes capillaries of conventional silica-based glass capillaries marginal due to their low reflectivity. The reflectivity of various materials were examined with the goal of finding alternate glasses, elements for doping glasses or surface coatings that may enhance these collimators for lithographic applications. Coating capillary surfaces with more reflective materials may be the most viable method for improving the radiation transport properties for capillary optics to be used in x-ray lithography.
The perturbed angular correlation technique has been applied to study the local environment of tantalum in nickel after ion implantation of hafnium and after laser-pulse melting. The magnetic hyperfine interaction at the daughter nucleus tantalum in nickel is used to determine the uniqueness of the tantalum lattice site. Several hafnium concentrations were employed and auxiliary measurements using ion-beam channeling, Rutherford backscattering and Auger electron spectroscopy were performed.
The stress evolution of Mo/Si and Ru/Si multilayers sputtered under the same processing conditions has been investigated. A series of Mo/Si multilayers was also prepared with varying sputtering pressures. The stress evolution of each multilayer displays a well-defined modulation concurrent with the deposition of Mo (Ru) and Si. Large stress develops during the early stages of deposition of each successive layer with Mo (Ru) exhibiting apparent tension and Si exhibiting apparent compression. In the Mo/Si multilayers, these initial transients cause curvature changes of, ∼ 2.5 to 4.5 N/m depending on the sputtering pressure. For Ru/Si the transients exceed 8 N/m and extend across a larger fraction of the total layer thickness. Intermixing and reaction at the interfaces of Mo/Si and Ru/Si multilayers lead to a volume contraction and consequently a contraction of the bilayer period. Moreover, volume contraction due to intermixing is a stress generating mechanism that may explain the initial transients in the stress evolution. The volume of the interdiffused regions of Mo/Si and Ru/Si multilayers was estimated by measuring the contraction of the bilayer period using x-ray diffraction. The results show a strong correlation with the size of the initial stress transients suggesting that intermixing may cause them.
The results of parallel RBS and photoluminescence studies of erbium implanted GaAs are presented. Low dose implantations do not produce any significant PL signals, and the dose must be in the range le14 to le15 /cm2 in order that Er related emission dominates in the PL spectrum. A comprehensive analysis of the effects of coimplantation with oxygen on the Er luminescence is reported and the data are compared to those of GaAs:Er and AIGaAs:Er samples grown by MBE. The evidence indicates that, at high doses, ErAs precipitates are formed unless oxygen is co-implanted, and that the Er atoms which produce the luminescence occupy substitutional Ga sites.