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The OVV blazar 3C 446 was monitored over seven months in 1997 with ground based telescopes and instruments on ESA's Infrared Space Observatory (ISO). The aim was to try to detect variations in the IR and see if these were correlated with optical variations. The object varied in the optical and near-IR during this period, but did not vary in the far-IR. Despite being a factor of ten weaker than in 1983, the optical-IR SED exhibited the same slope. The new far-IR observations from ISO allow us to determine the location of the turnover in the spectrum, caused by synchrotron self-absorption. It occurs just longwards of 100 μm.
Psilocybin is a classic psychedelic drug that has a history of use in psychotherapy. One of the rationales for its use was that it aids emotional insight by lowering psychological defences.
To test the hypothesis that psilocybin facilitates access to personal memories and emotions by comparing subjective and neural responses to positive autobiographical memories under psilocybin and placebo.
Ten healthy participants received two functional magnetic resonance imaging scans (2mg intravenous psilocybin v. intravenous saline), separated by approximately 7 days, during which they viewed two different sets of 15 positive autobiographical memory cues. Participants viewed each cue for 6 s and then closed their eyes for 16 s and imagined re-experiencing the event. Activations during this recollection period were compared with an equivalent period of eyes-closed rest. We split the recollection period into an early phase (first 8 s) and a late phase (last 8 s) for analysis.
Robust activations to the memories were seen in limbic and striatal regions in the early phase and the medial prefrontal cortex in the late phase in both conditions (P<0.001, whole brain cluster correction), but there were additional visual and other sensory cortical activations in the late phase under psilocybin that were absent under placebo. Ratings of memory vividness and visual imagery were significantly higher after psilocybin (P<0.05) and there was a significant positive correlation between vividness and subjective wellbeing at follow-up (P<0.01).
Evidence that psilocybin enhances autobiographical recollection implies that it may be useful in psychotherapy either as a tool to facilitate the recall of salient memories or to reverse negative cognitive biases.
Membranes with dimensions up to 10 mm x 15 mm have been fabricated in epitaxial 3C-SiC/Si wafers. An array of CTLM metal contacts was deposited onto the upper surface of the n-SiC membrane. Both Al/n-SiC and Pd/n-SiC contacts which were formed on the membrane and on the adjacent substrate have shown an ohmic current/ voltage response. Values of specific contact resistance, ρc, were measured directly on the membranes. These results have shown no consistent difference in ρc of the contacts located either on the membrane or off the membrane. The exposure of SiC surfaces to reactive ion etching in CF4 plasma during the fabrication of a membrane has resulted in ρc which was higher by a factor of 103 than with as-grown and KOH etched silicon surfaces.
The dynamic mechanical behaviour of a series of cyclic olefin copolymers (COCs) with varying norbornene content has been examined in the vicinity of the glass transition temperature, Tg. The temperature of the transition has been shown to increase linearly with increase in norbornene content. Measurements of both the elastic storage modulus, E′, and loss modulus, E″, have decreased exponentially with rise in temperature above Tg . A levelling-off in E″ occurred at >20 °C above Tg for all copolymers. The results of Dynamic Mechanical Thermal Analysis (DMTA) have been used in the identification of optimum conditions for hot embossing. At >20 °C above Tg in a region of viscous liquid flow, the hot embossing of COC has resulted in a full replication of channel depth without cracking or distortion.
About fifty species of terrestrial arthropods have been collected in Antarctica; these include mites, ticks, springtails, sucking lice, biting lice and flies. The mites include both free-living and parasitic forms, the springtails and flies are free-living, and the ticks and lice are parasitic. The ticks, parasitic mites, and biting lice are associated with birds, and the sucking lice with seals. The number of species are about equally divided between free-living and parasitic forms. The ability of insects and mites to survive the very low winter temperatures and frequent strong winds of Antarctica is of considerable interest; judged in relation to commonly accepted ideas of tolerance, the environment is extremely forbidding.
The frequency of herds affected with 13 different diseases is shown to bear a simple relationship to the frequency of affected animals. The relationship seems to be useful for predicting proportions of affected herds.
As more and more patients are planned in 3D, the need to verify their position and treatment in 3D also becomes apparent. Megavoltage (MV) and kilovoltage (KV) cone beam computed tomography (CBCT) provide 3D verification of patient position. However, the soft tissue contrast and thus the accuracy of delineation is superior with KV CT imaging. CBCT in conjunction with energy fluence maps from electronic portal imaging devices (EPIDs) could theoretically be used to verify the dose delivered. In this instance, a cross calibration between the KV CBCT and the EPID would be required which would not be necessary with MV CBCT. Adaptive planning with CBCT poses similar challenges for both KV and MV CBCT. Although KV CBCT can produce images with Hounsfield units (HUs) comparable with conventional CT in homogenous phantoms there are large discrepancies in inhomogeneous mediums. If the cupping artefact is corrected for in MV CBCT, the HU values can compare well with KV CBCT for homogenous media. However, advances need to be made to achieve a lower patient dose with MV CBCT. At present, the lower dose required for KV CBCT allows for more frequent imaging and better image quality.
The hot embossing of grating-based optically variable devices has been demonstrated in biaxially-oriented polypropylene (BOPP). The embossing of several types of optically variable device has been examined including portrait, non-portrait and 3 dimensional images. The images embossed into BOPP have displayed a novel optically variable effect when viewed in transmitted light. Embossing of the grating structures was examined over a range of temperatures (80-155 °C) at 135 kN force. High quality replication was achieved over a full embossing area of 80 x 80 mm at temperatures > 120 °C.
The reactive ion etching of a range of hard coatings (TiN, TiCN, CrN and TiAlN) has been examined as a function of rf power, flow rate and pressure. The films were deposited by filtered arc deposition (TiN, TiAlN and CrN) or low energy electron beam (TiCN) on polished disc substrates of M2 tool steel. The flat surfaces were lithographically patterned with a grating structure (∼1 μm pitch). The TiN and TiCN layers have shown significantly higher etch rates (100-250 nm/min) than the CrN and TiAlN (∼5 nm/min) coatings. These regimes of higher and low etch rate were identified as ion-enhanced chemical etching and physical sputtering, respectively. In CF4/O2 plasma, the etch rate of the TiN and TiCN layers increased with rf power, flow rate and pressure which were parameters known to enhance the density of active fluorine species. The etch rates of TiN and TiCN layers were higher in CF4/O2 plasma than in CHF3/O2 gases in which polymer deposition was produced at pressure ≥ 35 mTorr.
Diamond films were implanted with C+, Si+ or Sn+ ions at multiple energies in order to generate a uniform region of implantation-induced disorder. Analysis of the C+ implanted surfaces by micro-Raman spectroscopy has shown only minor increase in the proportion of nondiamond or sp2-bonded carbon at doses of 5 × 1013 - 5 × 1015 ions/cm2. In comparison, an amorphization of the structure was evident after implantation with either Si+ ions at a dose of 5 × 1015 ions/cm2 or with Sn+ ions at >5 × 1014 ions/cm2. At a given implantation dose, the etch rate of the diamond film in a CF4/O2 plasma increased with the mass of the implanted species in the order of C+, Si+ and Sn+. For a given implant species, the etch rate was directly proportional to vacancy concentration as controlled by the dose or the implantation-induced disorder.
This paper describes the influence of the topography of a lithographically patterned substrate (aluminium electrodes on a CVD diamond film) on the uniformity of sputtered ZnO films. Diamond films with an average surface roughness of ∼1nm, had aluminium electrodes (thickness 80nm, linewidth/space 2.6μm) patterned on them. ZnO was RF sputtered on to the substrate and the uniformity of the ZnO grain structure was examined using SEM, XRD and AFM. Abrupt changes in topography at the edges of the aluminium electrodes resulted in poor alignment of ZnO grains. SEM/AFM micrographs show misalignment of ZnO grains at the edges of the raised electrodes. When the electrodes were recessed into the diamond film, using a damascene-like process, the SEM/AFM micrographs showed improved grain uniformity of ZnO. XRD showed a significant increase in the c-axis (002) orientation and an absence of the (101) orientation. AFM micrographs also showed the improvement in the ZnO surface topography. These results may be of significance to high frequency Surface Acoustic Wave (SAW) devices.
Low resistance ohmic contacts for silicon devices commonly incorporate silicide materials as part of the contact. The electrical characterisation of ohmic contacts requires the use of various test structures such as the Cross Kelvin Resistor in order to determine the specific contact resistance ρc. This paper describes the results of using a three-dimensional finite element model of a Kelvin Resistor test structure in order to determine the influence of the electrical and geometrical parameters of a silicide-well on the magnitude of ρc. The same model of the test structure is further used to model the current density in the contact region. The results indicate that the presence of a silicide-well leads to reduced values of both ρc and the current density.
Pd/Zn/Au contacts to p-In0.53Ga0.47As/InP with various barrier layers (Pd, Pt or LaB,) to the indiffusion of Au have been examined by Rutherford Backscattering Spectrometry (RBS). For the metallisations with a barrier layer of Pd, the ageing of the contacts at 400°C for 20 h produced a widespread indiffusion of Au. In comparison, the incorporation of a layer of Pt or amorphous LaB6 prevented an indiffusion of Au and significantly reduced any outdiffusion of the semiconductor elements. The presence of the barrier layer of Pt or LaB6 produced little or no detrimental increase in specific contact resistance, ρc, for this contact system. Values of ρc in the range 8–10 × 10−6 Ω cm2 were obtained for all of the contacts based on Pd/Zn/Au after annealing at 500°C. A comparison has been made with the characteristics of Pt/Ti/Pt/Au contacts to p-In0.53Ga0.47As/ InP which were shown as stable against the indiffusion of Au.
The electrical characteristics of In, Sn, Au and Pt contacts on n-type Hg0.4Cd0.6Te formed in the presence and absence of prior In2+ implantation have been examined. Measurements of specific contact resistance made using a Transmission Line Model have shown that the unimtlanted In/Hg0.4Cd0.6 and Sn/Hg0.4Cd0.6 junctions gave values of pc = 3.0x10−3 to 4.0x10−3 ohm.cm2. Auger sputter profiles of the asdeposited In/Hg0.4Cd0.6 and Sn/Hg0.4Cd0.6 interfaces have shown a significant in-diffusion of the metal overlayer. The influence of shallow In2+ implantation prior to metallization was an increase in pc which occurred above a dose of 1013 ions/cm2. In contrast, Pt and Au formed Schottky barrier diodes on n-type Hg0.4Cd0.6 with øb=0.69eV for Pt and øb=0.79eV for Au. With prior In2+ implantation, both Pt and Au contacts exhibited an ohmic behaviour with pc= 2x10−1 ohm.cm2. These results have significance in the fabrication of devices for 1.0 -2.5μm optical communications.
We report on progress in the monolithic integration of a metal-semiconductor-metal (MSM) detector and transimpedence amplifier and of a photoconductive detector (PCD) with a metal-semiconductor field effect transistor (MESFET) in Hg1-xCdxTe. The layers of CdTe/n-type Hg1-xCdxTe were grown by MOCVD on semi-insulating GaAs substrates (2° misoriented 100). Fabrication of the devices was by an FET planar process; with a standard lift-off used to form Schottky metallization on both the interdigitated electrodes of the MSM detector (2μm width, 2μm spacing) and the gate of the MESFETs (5μm length, 100μm width). The MSM photodetectors exhibited breakdown voltages in the range 60 to 80V, a dark current of 1 Ona at 5V bias, and responsivities of > 1.0 A/W measured at 40V using CW 1.3um illumination. The integrated devices have been characterised by electrical and micro RBS techniques; the results were found to be strongly dependent on the stoichiometric x ratio of the Hg1-xCdxTe. This initial work demonstrates the suitability of Hg1-xCdxTe/GaAs structures in the fabrication of integrated optoelectronic circuits.
As the initial part of a research programme to assess the importance of geochemical factors in livestock production, a survey has been conducted on the copper (Cu) content of whole blood samples from cattle analyzed by the Veterinary Investigation Service over the period 1977-1980 inclusive. The area covered was restricted to England and the Welsh borders; data for Wales were not included, as they were not of a strictly comparable form, being based on plasma rather than on whole blood analysis.
Bradley Hill, 8·8 km (5½ miles) north-west of Ilchester, is a low hill projecting northwards from the Lower Lias plateau between Somerton and Langport and is capped by a thin band of Rhaetic clay.
The site of the Romano-British farmstead, 53 m (175 ft.) above sea level, is in a prominent and exposed position at NGR ST 4800 3034 (FIG. 1; PL. XVIII A). There are extensive views in all directions, particularly over the valley of the River Cary to the north and over the great expanse of King's Sedgemoor to the west. On the hilltop plateau, the calcareous ploughsoil was 0·20 to 0·25 m in depth, except around the sites of the Romano-British buildings.
Eight species of spiders belonging to two families were collected on northeastern Devon Island, N.W.T., in connection with the Canadian International Biological Program, Tundra Biome. They are Lycosidae: Tarentula exasperans Pickard-Cambridge; Erigonidae: Acartauchenius pilifrons (Koch), Collinsia spetsbergensis (Thorell), Diplocephalus barbatus (Koch), Erigone psychrophila Thorell, Hilaira vexatrix (Pickard-Cambridge), Minyriolus pampia Chamberlin, and Typhochraestus latithorax (Strand). The three most commonly collected species were E. psychrophila, T. exasperans, and H. vexatrix, in that order. New distributional data from other arctic localities for the above-mentioned species are given. A. pilifrons is recorded for the first time from the Nearctic Region and is described and figured in detail.