Terminal Configuration Research Articles

Temporal variations of the indoor wireless millimeter-wave channel

This paper reports experiments conducted near 30 GHz to characterize human-induced variations of an indoor radio channel for which both terminals are stationary. The dependence of envelope characteristics on various parameters (degree and localization of movement, terminal configuration, and spatial short-range fading level) is examined. In particular, it is found that the received envelopes may be considered realizations of only locally stationary processes, even when movement in the propagation environment is homogeneous. The results presented may be used in the design of broad-band wireless LANs and serve as a basis for the development of a theoretical model capable of predicting channel temporal variation characteristics under a variety of conditions.

Characterization of dark noise in CdZnTe spectrometers

Systematic measurements of dark noise spectra of CdZnTe x- and γ-ray spectrometers, correlated with the dc I-V characteristics and detector technology, are reported. The dark noise of two innovative CdZnTe spectrometer configurations are studied: metal-semiconductor-metal (MSM) resistive detectors with three terminals as well as heterostructure PIN detectors with thermally evaporated n+ CdS and p+ ZnTe contacts, which are fabricated on high pressure Bridgman CdZnTe (Zn=10%) crystals. The two innovative CdZnTe spectrometer configurations presented here exhibit very low dark (leakage) current. By reducing the dc value of the dark (leakage) current below 1 nA, shot noise becomes the dominant noise mechanism and the contribution of 1/f noise becomes negligible. The use of non-injecting contacts (evaporated gold) for the MSM detectors and the operation of the PIN detector in the reverse bias mode prevent generation-recombination noise which becomes dominant with injecting contacts (for example MSM detectors with evaporated indium and titanium contacts) or when operating the PIN detector in the forward bias mode. Surface leakage is reduced by applying surface passivation but is eliminated only by using the three terminal MSM configuration which exhibits simple shot noise instead of the suppressed shot noise observed in the two terminal MSM spectrometers. The noise measurements are useful for optimizing detector technology.

Phonon and magnetic excitations in neodymium pentaphosphate

The structure of NdP 5O 14 consists of cross-linked double chains of corner-sharing PO 4 tetrahedra extending parallel to the crystallographic a-axis. Each Nd atom is coordinated by eight O atoms. The NdO 8 polyhedra are isolated from each other and share no common O atoms. High-gain and long-lifetime laser action had been reported in NdP 5O 14 crystals. The neutron excitation spectra reveal a one-phonon density of states extended to about 180 meV with several distinct PO stretching bands at high energies. These features reflect the existence of different PO bond lengths among the terminal and bridging configurations and the associated atomic dynamics. Furthermore, magnetic scattering from Nd ions permitted the determination of the energy-level structure of the crystal-field-split Nd: 4 I 9 2 ground multiplet.

Inhibitory effects of arachidonic acid on nicotinic transmission in bullfrog sympathetic neurons.

Inhibitory effects of arachidonic acid on nicotinic transmission in bullfrog sympathetic neurons. J. Neurophysiol. 78: 2396-2401, 1997. Arachidonic acid (AA, 0.2-40 mu M) reversibly reduced the amplitude of the fast excitatory postsynaptic potentials and the underlying currents (fast EPSCs) of bullfrog sympathetic neurons evoked by preganglionic nerve stimulation in a Ca2+-deficient solution. AA reduced the acetylcholine (ACh)-induced nicotinic currents (nIACh) evoked by brief applications of ACh to the ganglion cells in a dose-related manner. AA reduced the maximum amplitude of nIACh estimated from the dose-response relationship without causing an appreciable change in the apparent dissociation constant. Indomethacin (2 mu M) and nordihydroguaiaretic acid (20 mu M), blockers of cyclooxygenase and lipoxygenase pathways, respectively, had no effect on the inhibition of fast EPSC by AA. AA did not obviously affect the preganglionic nerve terminal spike configuration, synaptic delay, facilitation, quantal content of transmitter release, or the presynaptic long-term potentiation elicited by the repetitive stimulation applied to the preganglionic nerve fibers. These results suggest that AA acts on an allosteric site of the nicotinic receptor-channel complex either directly or indirectly and in turn inhibits ion permeation through these channels without affecting the release of ACh from preganglionic nerve terminals.

Evidence for modification of the superconducting order parameter in YBa/sub 2/Cu/sub 3/O/sub 7-δ/ films by injection of a spin polarized current

We have deposited novel bilayer thin films of a ferromagnetic material and YBa/sub 2/Cu/sub 3/O/sub 7/ separated by a thin Au diffusion barrier to study the effects of a spin polarized nonequilibrium quasiparticle population on the superconducting order parameter. Thin films of YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta//, Au, and Permalloy (Ni/sub 0.8/Fe/sub 0.2/) were deposited by pulsed laser deposition onto (100) MgO, SrTiO/sub 3/, or LaAlO/sub 3/ substrates. A thin stripe of YBa/sub 2/Cu/sub 3/,O/sub 7-/spl delta//, was patterned and two pairs of Au cross stripes for current and voltage contact were deposited at each end. Between these contacts a Permalloy and a Au cross stripe was also deposited to serve as the spin polarized and unpolarized quasiparticle injection sources, respectively. Utilizing this pseudo-three terminal device configuration we have in some samples measured reductions in the superconducting order parameter at the ferromagnet contact as compared to the normal metal contact. Details of this experiment, issues for optimized fabrication, and theoretical issues are discussed.

Re-innervation patterns of chick auditory sensory epithelium after acoustic overstimulation

There is evidence from several studies showing that sensory cells which are destroyed by trauma in the chick auditory epithelium are replaced by new cells. The fate of neurons that innervate the injured and degenerating sensory cells in the lesion, and the temporal sequence of re-innervation of regenerated hair cells are not well understood. This study examined efferent terminals in the chick auditory sensory epithelium following acoustic overstimulation using synapsin-specific immunocytochemistry. Chicks were exposed to an octave band noise (1.5 kHz center frequency, 116 dB SPL, 16 h) and killed on each day from 0 to 9 days postexposure. In the proximal half of control whole mounts of the basilar papillae, synapsin-specific immunoreactivity stained efferent terminals throughout the abneural portion of the sensory epithelium (the short hair cell region). In this area, the labeling appeared as 2–3 bouton-shaped clusters along the abneural edge of each hair cell. After acoustic overstimulation, a lesion was observed at the abneural edge of the papilla where many short hair cells were lost. The center of the lesion was located at 40% distance from the proximal end of each traumatized papilla. Synapsin-specific labeling was not found in sites where expanded supporting cells had replaced missing hair cells. Hair cells which survived the trauma exhibited a shrunken apical area, and synapsin-labeled boutons were observed near their basal domains. New hair cells, which first appeared in the papilla 4 days after trauma, were not initially associated with synapsin-labeled boutons. Regenerated hair cells first displayed contacts with synapsin-labeled boutons 7 days after trauma. Nine days after acoustic overstimulation, most new hair cells appeared to be associated with synapsin-labeled boutons which resembled the normal horseshoe configuration of efferent terminals. The data suggest that direct contact with functional efferent synapses is not necessary for the generation and differentiation of new hair cells.

Novel asymmetry in the differential resistance of AuFe spin-glass wires

We have measured the differential resistance R=dV/dI of mesoscopic AuFe wires as a function of temperature T and dc current bias I. As a function of I, the low temperature resistance R(I) shows a maximum, reflecting a similar maximum in R(T) which is due to the onset of spin-glass order in these films. However, R(I) is asymmetric in I, this asymmetry being related to the presence of magnetic impurities in the AuFe films. The degree of asymmetry is sample-specific and is sensitive to the four terminal measurement configuration used to measure the sample. We believe the asymmetry is related to anomalous spin-scattering in the sample.

Automated guided vehicle traffic control at a container terminal

Because a large number of vehicles use the same infrastructural facilities, the control of automated guided vehicle (AGV) traffic at a container terminal is crucial to the system performance. A new modelling technique which has been used to successfully model the relevant aspects of traffic control is presented in this paper. The control can be imposed by using a hierarchical system of so called semaphores, thus it is possible to follow a structural approach in the design of a traffic control configuration. The technique has been used to model an elementary terminal configuration and tested in a simulation model.

The detection of clonal proliferation in granular lymphocyte‐proliferative disorders of natural killer cell lineage

The clonal proliferation of large granular lymphocytes can be detected in patients with T-cell-lineage granular lymphocyte-proliferative disorders (T-GLPD) by Southern blotting T-cell receptor genes. However, this cannot be applied to patients with natural killer-cell-lineage GLPD (NK-GLPD) as it lacks a clonal marker. We therefore investigated the use of two other diagnostic techniques in evaluating clonal proliferation in Japanese patients with NK-GLPD (n = 4) and T-GLPD (n = 3) by chromosomal analysis of peripheral blood mononuclear cells (PBMC) stimulated with either interleukin-2 or phytohaemagglutinin, and Epstein-Barr viral (EBV) genomic DNA analysis. Chromosomal analysis revealed abnormal karyotypes in the PBMC of three of four patients with NK-GLPD, whereas EBV analysis showed a monoclonal terminal configuration in the PBMC in the fourth patient. Southern blots revealed rearrangements of the TCR genes in all three patients with T-GLPD but in none of those with NK-GLPD. It is suggested that these methods may be useful in detecting the abnormal proliferation of large granular lymphocytes in NK-GLPD.

Study of closed-shell molecular complexes as possible laser media

We have evaluated a series of blue-green emitting molecular-complex materials (d/sup 0/ electronic system) from the point of view of their suitability as possible tunable laser media. All of them reveal a very strong, broad-band excited-state absorption (ESA), occurring between states of different configurations and positioned at the energy related to the crystal field parameter 10 Dq. The ESA strongly overlaps the luminescence spectra. Because of the nature of the terminal state of ESA, the high rate of ESA transitions can be ascribed to the efficient breaking of the Laporte selection rule, because of considerable admixture of % orbitals of ligands and/or p-orbitals of the central ion into the d-orbitals of the central ion in the terminal configuration, and to the existence of triplet terms in this configuration. We survey the ESA characteristics and compare its cross sections to those of stimulated emission. We interpret the obtained results by means of a configuration-coordinate model. Some possible avenues of future work are indicated. >

Development of the IBM 1500 computer-assisted instructional system

The IBM 1500 Instructional System was the only commercial system produced by a single manufacturer that had an integrated student terminal configuration providing a keyboard and light pen response mode, CRT-based graphics, audio, and static film projection. Experimental instructional systems had been developed by IBM prior to a prototype version of the 1500 Instructional System, which was tested at Stanford University. A production version of the 1500 System with changes in the CPU and the audio system and having the capability to run a maximum of 32 student stations was installed in over 30 sites beginning in the late 1960s. IBM's commitment to the development of this system was extensive but short-lived, as most sites were unable to maintain funding support for the system. In retrospect, the IBM 1500 System had capabilities yet to be supported on the microcomputer systems of the 1990s. >

X-ray photoelectron spectroscopy applications to corrosion and adhesion at metal oxide surfaces

X-ray photoelectron spectroscopy (XPS) has been widely used to characterise the surfaces of oxide films on metals and of bulk oxides. The surface sensitivity and the chemical information it provides are useful in examining the stability of the oxide surface with regard to hydration and hydroxylation, and in post-failure analysis of adhesive joints and delaminated coatings. Aluminium and titanium are used as examples, as they are important widely used materials, where resistance to hydration and bonding to the oxide surface are critical in many applications. Both oxide surfaces normally terminate in hydroxyl groups which on the titanium surface are readily resolved into bridged and terminal configurations. Although infrared evidence suggests the same structure on aluminium surfaces, this is generally not resolved in the oxygen XPS spectrum. A crucial part of the improved performance in adhesion and corrosion resistance of these metals is the improvement of the hydration resistance of the oxide film or the oxide—coating interface. Again XPS is useful in examining the mode of action of hydration blockers and conversion coatings.

The SOUT optical intersatellite communication terminal

Optical communications links between satellites promise to become an important element of future space infrastructure and are the subject of considerable development in Europe. Major advantages over conventional microwave links are low mass and power and smaller size leading to easier accommodation on the satellite. The Small Optical User Terminal (SOUT) is an optical communications package for interconnecting a low earth orbiting satellite to future optical data relay terminals and is the subject of an ESA development programme led by MMS (UK). The baseline terminal has a data rate of 2 Mbps over the return interorbit link and a mass of around 25 kg. The terminal configuration uses a unique combination of a periscopic coarse pointing assembly, refractive telescope, passive antivibration mount, combined acquisition and tracking sensor, and fibre coupled lasers and receivers. The paper discusses the design aspects for an asymmetric optical link based on the SOUT, covering link budgets, pointing, acquisition, and tracking and communications performance. Key SOUT subsystems are described and the structural and thermal configuration which allows these features to be combined in a compact unit is reported.

Transition from integral to pancake like vortices in single crystal YBa 2Cu 3O 7−δ

Single crystals of YBa 2Cu 3O 7−δ were studied in a six terminal voltage contact configuration and magnetic fields up to 8 T applied parallel and perpendicularly to the basal plane. Sample thickness dependent phase diagrams were obtained for the magnetic field dependent temperature T br , where vortices lose their coherence over the c-axis length of the sample.

GABAergic terminals in nucleus maznocellularis and laminaris originate from the superior olivary nucleus

The auditory brainstem nuclei, angularis (NA), magnocellularis (NM), and laminaris (NL) of the chicken, Gallus, contain terminals that stain for antibodies against the inhibitory neurotransmitter, gamma-aminobutyric acid (GABA). Some of these terminals originate from cells surrounding nucleus magnocellularis. Results from this study indicate that the majority of the GABAergic terminals found in NA, NM and NL originate from the superior olivary nucleus (SON). Injections of cholera toxin and horseradish peroxidase show that superior olivary nucleus (SON) neurons, which respond to pure tones, project bilaterally to NA, NM, and NL. NA and NL are reciprocally connected with the SON. More NA cells project to the SON than NL cells. While SON neurons project to NM, NM neurons do not project axons back to the SON. The configuration of SON terminals in NA, NM and NL matches the pattern of GABA-immunoreactive puncta seen in these three nuclei: they surround individual NM cells, congregate in the dendritic neuropil of NL, and blanket the NA. The data indicate that NA, NM and NL may be affected by two different inhibitory cell types: local interneurons and SON neurons. Patterns of connectivity described in this report suggest that the activity of NA cells could influence NM and NL cell physiology. Specifically, increases in NA cell activity could augment the effects of GABAergic SON neurons on NM and NL. Hence, binaural perception in the chicken may be more dependent upon changes in intensity cues than previously believed.

Distinct clonotypic Epstein–Barr virus-induced fatal lymphoproliferative disorder in a patient with wiskott-aldrich syndrome

Recently, reports of Epstein-Barr virus (EBV)-induced lymphoproliferative disorders (LPD) have increased in number among immunosuppressed recipients of organ transplants. The importance of analyzing both the immunoglobulin gene and EBV termini is advocated for the investigation of pathogenetic mechanisms for clonal proliferation in EBV-induced LPD; however, the oncogenic mechanisms of EBV-induced LPD remain unclear. Furthermore, there are very few clonotypic studies of EBV-induced LPD in patients with primary immunodeficiency diseases. The authors studied the clonality of an EBV-induced fatal LPD in a 20-year-old patient with Wiskott-Aldrich syndrome (WAS), an X-linked recessive primary immunodeficiency disease. An autopsy showed non-Hodgkin lymphoma of B-cell origin with diffuse large cells in both systemic lymph nodes and extranodal organs. Immunohistochemical and Southern blot analyses showed polyclonal rearrangement of immunoglobulin genes in most of the lesions except for the pulmonary hilar lymph node. Furthermore, the analysis of restriction fragment length polymorphism with several fragments from EBV genome indicated that EBV genomes in all lesions were identical; however, a single but different-sized EBV termini was detected in every EBV-positive lesion when probed with the EcoRI-Dhet spanning terminal repeat region of EBV. The EBV-induced fatal LPD in a patient with WAS showed the characteristic clonotype, polyclonal immunoglobulin gene rearrangement, and monoclonal EBV terminal configuration. Furthermore, EBV termini in each lesion varied in size. This particular clonotype implicates several unique pathogenetic mechanisms for clonal proliferation of EBV-induced LPD.

Walking distance minimization for airport terminal configurations

Passenger walking distance is a major consideration in determining the configuration of an airport terminal. Given the size of a terminal in terms of the number of aircraft gates, the mean passenger walking distance is derived based on: the fraction of arriving, departing and transferring (hub and non-hub) passengers; gate spacing; spacing requirement for aircraft maneuvering; and the terminal block dimensions. Pier, satellite, and pier-satellite terminal configurations are considered. It is assumed that all aircraft parking positions are capable of handling any type of aircraft and passengers are equally distributed among all the gate positions over the life of the facility. Two groups of hub transfers are defined to accommodate different levels of hub and spoke operations. The optimum terminal geometry in terms of the number of piers or satellites and their sizes, is obtained by minimizing the mean walking distance for all the passengers. The probability distribution of the walking distance of a passenger is generated by simulation. Given an acceptable walking distance, several statistical parameters that are suitable to compare the optimum geometries for different configurations are reported. It is shown that in most cases the lower and the upper bounds of the optimum number of piers or satellites are proportional to the square root of the total number of gates in the terminal. For a wide range of passenger mixes and numbers of gates, a semi-centralized pier configuration appears to be the best terminal configuration with respect to passenger walking. Guidelines for the selection of the best terminal configuration for non-hub, moderate-hub and all-hub (wayport) terminals are presented. The application of the proposed method in a terminal expansion situation is given.

Effects of cell losses on picture quality in ATM networks

Asynchronous transfer mode (ATM) is viewed as the technique that forms the basis of broadband integrated services digital networks (B-ISDN). In ATM, the cell losses that accompany congestion during cell multiplexing are believed to cause a significant deterioration in quality. In this paper, we study the effects of cell losses on image quality from the standpoint of subjective evaluations. First, the impairment factors that cause deterioration in the received video are extracted for the various network and terminal configurations that are assumed. Next, with the impairment factors as the parameters, a computer simulation was created of the impairment that accompanies cell loss and the subjective quality was studied using a 320-frame video signal. It was clearly shown that of all the impairment factors, the five major influences on quality are the number of lost cells, the number of picture elements (pels) in the impaired region, the amplitude distortion of the image in the impaired region, the shape of the impaired region, and the bursti-ness of cell loss. In addition, when consecutive frames are inquired as a result of cell loss, except when only one segment is seen, the total number of impaired frames hardly affects subjective image quality. Finally, based on these evaluation results, we discuss cell loss quality in pulse code modulation (PCM) and provide guidelines for designing networks and terminals.

Dynamics of polar filament discharge and sporoplasm expulsion by microsporidian spores

AbstractSpores of the microsporidium Nosema algerae were stimulated to germinate in vitro while observed with video‐enhanced contrast microscopy. Field‐by‐field playback of tape‐recorded sequences yielded the first serial illustrations and kinematic analysis of the explosive discharge of the polar filament and the sporoplasm. The filament emerges from the anterior pole of the spore in a regularly pitched helicoidal course along a nearly straight axis, with a mean maximum instant velocity of 105 μm/s. Just before elongation is completed the filament tip follows a tortuous path that often results in a curved or spiralling terminal configuration. Then elongation stops and, after a lag that may vary from less than 15 to over 500 ms, the sporoplasm pours out at the filament tip forming a globule that quickly grows up to a size larger than its original volume within the spore. Concomitantly, the helical filament becomes straightened and frequently the spore body is pulled forward. Thereafter a relaxed filament, usually 5–10% shorter than when maximally extended, remains connecting the empty spore case and the sporoplasmic droplet. Experiments with hyperosmolar media produced a considerable slowdown of filament extrusion and often precluded sporoplasm discharge. The present results are fully consistent with the hypothesis of a hydrostatic pressure‐triggered mechanism of spore germination, and revealed that the process is composed of two discrete phases separated by a variable lag: (1) complete eversion of the polar filament, and (2) passage of the main sporoplasm mass along the tube. The data provide a preliminary basis toward the conception of a quantitative physical model of microsporidian spore germination. © 1992 Wiley‐Liss, Inc.

A local area radio network utilizing CSMA/CD scheme for its inter-radio base station network

The cordless configuration of computer terminals and other systems is considered in various applications in recent years. Cordless terminals are expected to have the following advantages: the flexibility of the terminal user is enhanced; the geographical range of the service is enlarged; and the reconstruction of the local-area network is made unnecessary when the office organization is to be modified. On the other hand, excellent communication quality is difficult to maintain in radio transmissions due to the effects of fading and shadowing. Moreover, the efficient use of limited frequency resources should be considered. Previous studies have already pointed out that the communication quality and the throughput are greatly improved by providing more than one base station for the random access radio channels in the radio communication system. In that case, however, the selection control of a packet received by more than one base station is not easy. No study on this problem has been made. This paper proposes an autonomous and distributed selection control of a packet received by more than one base station, on CSMA/CD LAN. The fundamental performances are analyzed and evaluated, and the usefulness of the system as an inter-radio base station network in CSMA/CD LAN is indicated.