Showing papers by "Alcatel-Lucent published in 1982"

NMR chemical shift imaging in three dimensions

Abstract: A method for obtaining the three-dimensional distribution of chemical shifts in a spatially inhomogeneous sample using Fourier transform NMR is presented. The method uses a sequence of pulsed field gradients to measure the Fourier transform of the desired distribution on a rectangular grid in (k,t) space. Simple Fourier inversion then recovers the original distribution. An estimated signal/noise ratio of 20 in 10 min is obtained for an "image" of the distribution of a 10 mM phosphorylated metabolite in the human head at a field of 20 kG with 2-cm resolution.

Electronic audio communications system with versatile message delivery

Abstract: An advanced electronic telecommunications system is provided for the deposit, storage and delivery of audio messages to both users and non-users with limited access provided to the non-user under the control of the user. A Voice Message System (10) interconnects multiple private exchanges (12) of a subscriber with a central telephone office (22). Individual subscriber users may access the Voice Message System (10) through ON NET telephones (18) or OFF NET telephones (24). Selected non-users may be allowed access through the OFF NET telephones (24), the scope of the access of the selected non-users being determined by a subscriber user. The Voice Message System (10) includes an administrative subsystem (60), call processor subsystem (62) and a data storage subsystem (64). The Voice Message System (10) enables the user to deposit a message in data storage subsystem (64) for automatic delivery to other addresses connected to the system and to designate the message for priority transmission. The recipient is able to redirect the message from a message originator to a second recipient and the second recipient can re-redirect it to a third recipient. The Voice Message System (10) also enables a user to access the system to determine if any messages have been in data storage subsystem (64) for him. Prerecorded instructional messages are deposited in the data storage subsystem (64) for instructing a user or a selected non-user on their progress in using the system.

Hydrogen-evolving semiconductor photocathodes: nature of the junction and function of the platinum group metal catalyst

Abstract: Noble metal incorporation in the surface of p-type semiconductor photocathodes to catalyze hydrogen evolution leads to efficient solar to chemical conversion if a set of energetic and kinetic criteria are satisfied: (1) the semiconductor-catalyst junction barrier height must be equal to or greater than that of the semiconductor H/sup +//H/sub 2/ junction; (2) the recombination velocity of photogenerated electrons at the semiconductor-catalyst interface must be low; (3) the overpotential for hydrogen evolution at solar cell current densities (approx.30 mA/cm/sup 2/) must be minor. Because of substantial differences in the vacuum work functions of Pt, Rh, Ru, and the (redox potential of the) H/sup +//H/sub 2/ couple, the barrier heights for junctions of each of the four systems with p-InP ought to vary widely. Yet experiments show that all p-InP(M)/H/sup +//H/sub 2/ junctions, where M = Pt, Rh, Ru, or no metal, have essentially the same approx.0.7-V gain in onset potential for hydrogen evolution relative to Pt/H/sup +//H/sub 2/. We attribute the similarity to the known lowering of metal work functions upon hydrogen alloying. Such alloying increases the barrier height and thereby the gain in onset potential over that anticipated from the vacuum work functions. The barrier height, measured as themore » limiting value of onset potential gain at high irradiance, approaches in all cases the Fermi level difference of p-InP and H/sup +//H/sub 2/ (0.9 +/- 0.2 eV). That Fermi level pinning by interfacial states is not the cause of the similar barriers is evident from the reversible decrease in onset potential with hydrogen depletion and by a unity diode perfection factor of the p-InP(Rh)/H/sup +//H/sub 2/ photocathode, which indicates no measurable interfacial recombination of photogenerated carriers. In agreement, the quantum efficiency of carrier collection (hydrogen evolution) nears unity.« less

New display based on electrically induced index‐matching in an inhomogeneous medium

Abstract: The operation of a new light modulation device that employs electric field controlled light scattering in an inhomogeneous medium is described. The orientation of a nematic liquid crystal, contained in micrometer sized inclusions in a nonabsorbing solid, is changed to produce a varying refractive index. When the refractive index of the liquid crystal matches that of the solid, the composite medium is nonscattering and transparent. If the refractive indices do not match, the medium is scattering and opaque. High contrast ratios have been measured for transmitted light with a response time of a ∼1 ms. The application of this technique to passive display devices is discussed.

Robust-resistant spectrum estimation

Abstract: Conventional spectrum estimates of both the smoothed-periodogram and autoregressive variety lack robustness toward outliers in the original data. Outliers and other local perturbations are modeled by non-Gaussian additive noise, which is zero most of the time. Correspondingly, the lack of robustness of the conventional estimates of the spectrum manifest not only inflated variances but also damaging asymptotic biases. This paper discusses robust-resistant methods of spectrum estimation which do not suffer in this way. The main approach involves "data cleaning" by either one-sided or two-sided outlier interpolators based on autoregressive approximations. The autoregressive coefficients are themselves estimated robustly in an iterative loop along with the data-cleaning operation. The well-cleaned data are then used along with the autoregressive model to form smoothed spectral density estimates via prewhitening. Study of the so-called "linear part" of the nonlinear outlier interpolator algorithm shows that considerable bias reduction is realizable through use of the robust procedure. Some examples of applications of the robust methodology are presented. Special considerations for real-time processing and large data sets are discussed. Extensions of the method to cross-spectrum estimation, missing data, and irregularly spaced data problems are briefly mentioned.

Optical response time of In0.53Ga0.47As/InP avalanche photodiodes

Abstract: Heterojunction In0.53Ga0.47As/InP avalanche photodiodes have recently been observed to have a response to long‐wavelength optical pulses which contains both fast and slow components. We present evidence that the slow response is limited by charge pile‐up at the semiconductor heterointerface. We find that the speed of response depends on the degree of compositional grading in the heterointerface region. The response time can be significantly reduced for compositional grading lengths of greater than 600 A depending on the doping and depletion region width in the In0.53Ga0.47As layer.

Large conductivity changes in ion beam irradiated organic thin films

Abstract: Using 2‐MeV Ar+ ion beam irradiation, we have generated conducting patterns in otherwise high resistivity, organic thin films of 3,4,9,10‐perylenetetracarboxylic dianhydride (PTCDA), 1,4,5,8‐napthalenetetracarboxylic dianhydride (NTCDA), and Ni phthalocyanine (NiPc). The room‐temperature resistivity of the films changes by 14 orders of magnitude from its as‐deposited value of ρ≳1010 Ω cm to ρ≅5×10−4 Ω cm at ion doses of 1017 cm−2. The temperature (T) dependence of the resistivity follows ρ(T)∝exp[+(T0/T)1/2] over a wide range of dose and temperature. The characteristic temperature T0 is found to be a function of dose. The exp(T0/T)1/2 behavior of ρ(T) is consistent with charge transport due to hopping between isolated, conducting islands.

Stress tuning of the metal-insulator transition at millikelvin temperatures

Abstract: A high-resolution scan of the metal-insulator transition in Si:P at millikelvin temperatures has been obtained by applying uniaxial stress A sharp, but continuous, metal-insulator transition is resolved, with conductivities below Mott's "minimum" value σ_M These measurements join smoothly with previous low-resolution experiments, ruling out any discontinuity at σ_M The reproducible critical behavior disagrees with predictions of existing scaling theories of localization

Low-loss Ti:LiNbO 3 waveguide bends at λ = 1.3 µm

Abstract: Low-loss waveguide bends are necessary for many proposed integrated optical circuits. The bend loss associated with an S -shaped transition connecting offset 6 μm wide titanium-indiffused lithium niobate strip waveguides has been measured as a function of transition length and initial Ti metal thickness for 1.3 μm wavelength. Losses as low as 0.2 ± 0.2 dB have been achieved for a transition between offset parallel waveguides with a 0.1 mm lateral and 3.25 mm longitudinal separation. The bend loss is shown to be strongly dependent on the mode confinement and less sensitive to the shape of the transition curve.

Giant dielectric constants at the approach to the insulator-metal transition

Abstract: We have measured the real and imaginary parts of the dielectric susceptibility of insulating samples of P-doped Si at millikelvin temperatures at 400 MHz using a resonant transmission cavity. We find that the real part is enhanced by more than two orders of magnitude over the isolated donor polarizability, and we determine the exponent which describes the critical divergence of the real part at the insulator-metal transition by fitting the temperature dependence of the corresponding imaginary part. The form of the observed divergence remains unexplained theoretically.

Organic‐on‐inorganic semiconductor contact barrier devices

Abstract: The organic compound 3,4,9,10‐perylenetetracarboxylic dianhydride (PTCDA) has previously been observed to undergo a large increase in conductivity on irradiation with energetic particle beams. In this letter, we describe the electrical characteristics of novel rectifying junctions employing unirradiated PTCDA vapor deposited onto 10‐Ω cm p‐Si substrates. The PTCDA‐Si contact barrier has a height of φB = 0.74 eV. The resulting diodes undergo avalanche breakdown at VB = 230 V, and exhibit current densities at 1/2 VB of ⩽50 μA/cm2. In addition, the forward current‐voltage (IF−V) characteristics are strongly dependent on the contact metal used on the top PTCDA surface. The best results obtained were for diodes employing Ti contacts which gave nonhysteretic, stable IF‐V characteristics with an ideality factor of n = 1.7. Several properties of the as‐deposited PTCDA are also discussed. The rectifying characteristics reported here, coupled with the properties of irradiated PTCDA, suggest many unique device app...

Isolated ultracold porphyrins in supersonic expansions. I. Free‐base tetraphenylporphyrin and Zn‐tetraphenylporphyrin

Abstract: In this paper we report the results of an experimental study of the fluorescence excitation spectra and of the time‐resolved emission of Zn‐tetraphenylporphyrin (ZnTPP) and of free‐base tetraphenylporphyrin (H2TPP) seeded in pulsed supersonic expansions of He. We have studied the S0→S1 transition (the Q band) and the S0→S2 transition (the Soret, B band) of ZnTPP, as well as the S0→S1x transition (the Qx band), the S0→S1y transition (the Qy band), and the S0→S2x transition (the Bx band) of H2TPP. Information was obtained on the electronic energy levels, the vibrational level structure, the details of low‐frequency nuclear motion, and some characteristics of electronic relaxation.

Deep levels in In0.53Ga0.47 As/InP heterostructures

Abstract: We report on deep levels in In0.53Ga0.47 As/InP heterostructure avalanche photodiodes grown by liquid‐phase epitaxy. Two electron levels have been identified and studied using both admittance spectroscopy and a static capacitance‐voltage technique. One level, found only in the InP layer, is acceptor‐like with an activation energy of etA = 0.20±0.02 eV and has a density in the bulk of the InP layer of NtA≊ 1015 cm−3. The density of the trap increases sharply at the In0.53Ga0.47 As/InP heterointerface to a value nearly ten times the background carrier concentration in this region. Filling of this trap at low temperatures reduces the conduction band discontinuity at the heterointerface from Δec = 0.19 to 0.03 eV due to repulsion of the bands. The second trap, which is characteristic only of the In0.53Ga0.47 As, has an activation energy of etB = 0.16±0.01 eV, and a density of between 3×1013 and 8×1013 cm−3.

Hadron production by e+e- annihilation at center-of-mass energies between 2.6 and 7.8 GeV. I. Total cross section, multiplicities, and inclusive momentum distributions

Abstract: Measurements of multihadron production in e+e− annihilation at center-of-mass energies between 2.6 and 7.8 GeV are presented. Aside from the narrow resonances ψ(3095) and ψ(3684), the total hadronic cross section is found to be approximately 2.7 times the cross section for the production of muon pairs at c.m. energies below 3.7 GeV and 4.3 times the muon-pair cross section at c.m. energies above 5.5 GeV. Complicated structure is found at intermediate energies. Charged-particle multiplicities and inclusive momentum distributions are presented.

The quenching of Na(3 2P) by H2: Interactions and dynamics

Abstract: An eight‐configuration diatomics‐in‐molecules formalism with symmetrically orthogonalized diabatic input is used to calculate the three lowest potential energy surfaces and nonadiabatic couplings for Na+H2 collisions. The singlet diatomic input for NaH and the singlet and triplet diatomic input for H−2 are chosen to reproduce the accurate adiabatic curves for those cases, and the diatomic input for H2 is based on theoretical interpretations of the resonance states. Trajectory calculations are carried out using the calculated 2 2A′ potential surface and nonadiabatic couplings, and the choice of H−2 input is found to sensitively affect the H2 vibrational excitation in the resonance‐line quenching process. One H−2 curve, based on the work of Wadehra and Bardsley, yields an amount of vibrational excitation similar to that observed experimentally. The resulting set of potential energy surfaces provides a reasonable microscopic interpretation of the chemical dynamics of the quenching process Na(3p2P)+H2(v = 0, ...

Evidence for hydrogen bonding of bound dioxygen to the distal histidine of oxycobalt myoglobin and haemoglobin

Abstract: The origin of the differences in oxygen binding energy in various haemoglobins and myoglobins has long been debated. Perutz1 proposed that the haem-coordinated histidine (proximal histidine) strains the haem iron in low affinity globins but relaxes it in high affinity globins. The existence of such tension in T-structure deoxyhaemoglobin (deoxyHb) was recently confirmed by electron paramagnetic resonance (EPR)2,3, resonance Raman4,5 and NMR6 spectroscopy. Although its contribution to the free energy of cooperativity is insignificant in the deoxy state, the tension at the haem is considered to be ∼1 kcal mol−1 for the ligated form in which the haem iron moves into the porphyrin plane7. The remaining free energy is probably stored in other parts of the molecule. Therefore, a study of the stabilization mechanisms of the oxygenated form became increasingly important. A hydrogen bond between the bound oxygen and the distal histidine has been proposed by Pauling8; this would be expected to stabilize the oxy form of the protein and could contribute to the regulation of the oxygen affinity through the oxygen dissociation rate. A series of EPR and functional studies on various cobalt-substituted monomeric haemoglobins and myoglobins suggested the presence of such hydrogen bonding8–12 and it has recently been established in crystals of oxy iron myoglobin (oxyFeMb)13 and in oxyhaemoglobin14. Here we present resonance Raman spectra of the oxy forms of cobalt–porphyrin-substituted myoglobin and haemoglobin (CoMb and CoHb) recorded in buffered H2O and D2O solutions at 406.7 nm excitation. Only the Raman lines corresponding to the O—O stretching mode of the bound oxygen15, appearing near 1,130 cm−1, are shifted (2–5 cm−1) on replacement of H2O by D2O; no other vibrations, including the Co—O2 stretching mode, exhibit any frequency shifts. This indicates that the bound oxygen in oxyCoMb and in both subunits of oxyCoHb interacts with the adjacent exchangeable proton, and confirms the formation of a hydrogen bond between the bound oxygen and the distal histidine9.

Apparatus for measuring in situ the state of oxidation-reduction of a living organ

Abstract: Apparatus having application to surgical operations has an ultra-violet laser pulse generator (1), an infrared laser pulse generator (3), an optical fibre (11) which transmits these pulses in one direction to the organ (13) and returns the fluorescence emitted by the organ together with reflected infrared radiation. Said returned radiation is detected by two receivers (25 and 20) and a circuit (31) for processing the electric signals delivered by said receivers.

Phosphorus-31 nuclear magnetic resonance studies of bioenergetics in wild-type and adenosinetriphosphatase(1-) Escherichia coli cells.

Abstract: By use of 31P NMR, the transmembrane pH gradient (delta pH) and the intracellular levels of phosphorylated metabolites were measured in aerobic suspensions of wild-type Escherichia coli cells in the presence and absence of the adenosinetriphosphatase (ATPase) inhibitor dicyclohexylcarbodiimide (DCCD); the same parameters were also determined in E. coli mutants deficient in ATPase activity under both anaerobic and aerobic conditions. A method is described by which dense suspensions of E. coli cells (approximately 3 X 10(11) cells/mL) were oxygenated so that steady-state O2 levels in the suspensions were far greater than the Km for O2 consumption. Under these conditions, in wild-type MRE600 cells, the intracellular concentrations of PI, NTP, and NDP were measured to be 3.0 +/- 1.5, 8 +/- 1, and 1.2 +/- 1 mM, respectively, while the intracellular pH was approximately 7.5 over the external pH range studied (6 to approximately 7.0). Upon treatment with DCCD, the intracellular NTP level was drastically reduced and intracellular Pi concentration increased in respiring wild-type cells; in the same cells, however, DCCD did not affect the intracellular pH and the delta pH. During respiration in the presence of lactate, ATPase- cells established a delta pH but failed to synthesize any detectable levels of NTP. Conversely, ATPase- cells accumulated high levels of NTP but did not generate a delta pH during glycolysis under anaerobic conditions. These results are in complete agreement with the generally accepted chemiosmotic hypothesis. 31P NMR data on intact ATPase- NR70 cells were in agreement with the previously proposed [Rosen, B. P., Brey, R., & Hasan, S. (1978) J. Bacteriol. 134, 1030] existence of a proton leak in this strain which is sealed by DCCD or by spontaneous mutation into strain NR71. However, the NMR data also indicated that other major differences exist between NR71 and NR70 cells.

Best simultaneous Diophantine approximations. I. Growth rates of best approximation denominators

Abstract: This paper defines the notion of a best simultaneous Diophantine approximation to a vector a in Rn with respect to a norm 11 11 on Rn. Suppose a is not rational and order the best approximations to a with respect to II II by increasing denominators I qI < q2 < * It is shown that these denominators grow at least at the rate of a geometric series, in the sense that g(a, 11 * 11) =ihmjinff(q) / I + I Let g(II * 11) denote the infimum of g(a, II *I) over all a in Rn with an irrational coordinate. For the sup norm 11 115 on R2 it is shown that g(lI * II,) ?0 = 1.270+ where 4= 02 + 1.

Pictorial similarity judgments and the organization of visual memory in the rhesus monkey.

Abstract: The organization of visual memory for pictures was studied in the rhesus monkey. Two monkeys were tested in a same/different task in which sequentially presented pictures were compared to each other in a pair-wise fashion. The resulting confusion matrixes were analyzed using a multidimensional scaling procedure to obtain two- and three-dimensional graphic representations of the stimulus space. In Experiment 1, the monkeys' confusion errors caused pictures of human and rhesus monkey faces to fall in the same region of multidimensional space, which suggested that the monkeys categorized facial stimuli. A similar effect was found for pictures of different types of fruit. Experiment 2 replicated the categorization of faces with a more diverse collection of human and nonhuman primate faces. Experiment 3 explored the fruit category by varying stimulus attributes orthogonally. The results from this experiment showed that both monkeys encoded the pictures in this category by type of fruit (apples or grapes) and color (red or yellow). Taken together, these studies indicate that rhesus monkeys will treat some classes of pictorial stimuli categorically in visual memory.

A semantic model of types for applicative languages

Abstract: If integer constants are added to the syntax of the pure lambda calculus, then primitive integer values have to be added to the underlying domain V of values. Unlike functions, primitive values should not be applied; we want a run-time error to occur if an attempt is made to apply them as functions. Expressions that might lead to run-time errors are separated out by imposing a “type” structure on expressions. A systematic model of types is developed, in which types are formalized as “ideals” (sets with a certain structure). Polymorphic functions are handled by introducing a quantifier for taking conjunctions of types. Operations for constructing new types from old lead to the consideration of higher-order or meta types, which are called “kinds” to avoid confusion with types. Finally, the semantic model of types is applied to show the soundness of a proof system for inferring the types of expressions.

Spontaneous Photoelectrolysis of HBr and HI

Abstract: Spontaneous and efficient photoelectrolysis of HBr into hydrogen and bromine is reported for light of wavelengths to 950 nm in a p-n photoelectrolysis cell composed of a p-InP photocathode with noble metal catalyst islands on the surface and an n-MoSe/sub 2/ or an n-WSe/sub 2/ photoanode. Photoelectrolysis of HI with the same photoelectrodes yields hydrogen and iodine and simultaneously produces electrical power. The efficiency of the photoelectrolysis is calculated by two methods, one based on the stored free energy and the other based on electrical power saved. The efficiencies for HBr photoelectrolysis by 632.8 nm light are 7.8%, if calculated by the first method, and 11.2%, if calculated by the second. 34 refs.

Electronic audio communications systems network

Abstract: An advanced electronic telecommunications system is provided for the deposit, storage and delivery of audio messages to both user and non-users with limited access provided to the non-user under the control of the user. A Voice Message System (10) interconnects multiple private exchanges (12) of a subscriber with a central telephone office (22). Individual subscriber users may access the Voice Message System (10) through ON NET telephones (18) or OFF Net telephones (24). Selected non-users may be allowed access through the OFF NET telephones (24), the scope of the access of the selected non-users is determined by a subscriber user. The Voice Message System (10) includes an administrative subsystem (60), call processor subsystem (62) and a data storage subsystem (64). The Voice Message System (10) enables the user to deposit a message in data storage subsystem (64) for automatic delivery to other addresses connected to the system. Individual systems (42) can be linked in a network (40) by either a digital data link (48) or a public telephone network (51). The Voice Message System (10) also enables a user to access the system to determine if any messages have been in data storage subsystem (64) for him. Prerecorded instructional messages are deposited in the data storage subsystem (64) for instructing a user or a selected non-user on their progress in using the system.

Quaternary-transformation-induced changes at the heme in deoxyhemoglobins.

Abstract: Quaternary-structure-induced differences in both the high- and low-frequency regions of the resonance Raman spectrum of the heme have been detected in a variety of hemoglobins. These differences may be the result of (1) changes in the amino acid sequence, induced by genetic and chemical modifications, and (2) alterations in the quaternary structure. For samples in solution in low ionic strength buffers, differences in the 1357-cm-1 line (an electron-density-sensitive vibrational mode) correlate with differences in the 216-cm-1 line (the iron-histidine stretching mode). Thus, changes in the iron-histidine bond and changes in the pi-electron density of the porphyrin depend upon a common heme-globin interaction. The quaternary-structure-induced changes in the vibrational modes associated with the heme demonstrate that there is extensive communication between the heme and the globin and impact on models for the energetics of cooperativity. The local interactions of the iron-histidine mode are energetically small and destabilize the deoxy heme in the T structure with respect to the R structure. Therefore, these interactions must be larger in the ligated protein than in the deoxy protein to obtain a negative free energy of cooperativity. Additionally, our data imply that the deprotonation of the proximal histidine does not play a major role in the energetics of cooperativity. On the other hand, models for cooperativity that require conformational changes in the iron-histidine bond or direct interaction between the porphyrin and the protein are qualitatively consistent with the observed variation of heme electronic structure in concert with protein quaternary structure.