An experimental design approach is used to determine which factors (design parameters) of spectrally modulated, spectrally encoded (SMSE) waveforms have the greatest impact on coexistence with other communication waveforms. The SMSE framework supports cognition-based, software defined radio (SDR) applications and is well-suited for coexistence analysis. For initial proof-of-concept, a two factor (parameter), three-level (value) experimental design technique is applied to a coexistent scenario to characterize SMSE waveform impact on direct sequence spread spectrum (DSSS) receiver performance. The experimental design methodology reliably captures factor-level sensitivities and identifies those factors having greatest impact on system coexistence behavior (bit error variation). Given these initial results and its effectiveness in other engineering fields, it is believed that experimental design may pave the way for developing more rigorous waveform design methods and allow more robust coexistence analysis of conventional, DSSS and SMSE waveforms.

The interference suppression capability of spectrally modulated, spectrally encoded (SMSE) signals is characterised for multiple channels containing partial band interference. The recently-introduced SMSE analytic framework is well-suited for software defined radio applications where coexistence and interference suppression (avoidance) is essential. Performance improvement is demonstrated using adaptive interference suppression within the SMSE framework over a wide range of interference-to-signal power ratios.

We derive recurrence relations between phase space expressions in different dimensions by confining some of the coordinates to tori or spheres of radius R and taking the limit as R → ∞. These relations take the form of mass integrals, associated with extraneous momenta (relative to the lower dimension), and produce the result in the higher dimension.

We derive expressions for the phase-space of a particle of momentum p decaying into N particles, that are valid for any number of dimensions. These are the imaginary parts of so-called 'sunset' diagrams, which we also obtain. The results are given as a series of hypergeometric functions, which terminate for odd dimensions and are also well-suited for deriving the threshold behaviour.

Initial acquisition performance of a transform domain communication system (TDCS) is characterized via modeling and simulation (M&S). A TDCS with interference suppression capability differs from typical spread spectrum systems in two primary ways. 1) spectrally crowded regions are avoided via adaptive spectral notching, and 2) no carrier modulation is employed. Thus, minimal signal structure exists for synchronization purposes. Initial TDCS acquisition performance is investigated for various synchronization codewards and several acquisition methods, e.g., direct time correlation (DTC) and German's technique, using both peak and threshold detection techniques. IMATLAB(R) simulation results indicate that a TDCS can achieve a high probability of detection (P/sub d/>0.9) for relatively low input signal-to-noise ratios (SNRs), as low as -23 dB for peak detection and -21 dB for threshold detection. Extensive computer simulations and subsequent analysis indicates that a TDCS can adequately acquire and accurately align a locally generated reference waveform with the received noise-like TDCS signal.

This research characterizes the initial acquisition performance of a TDCS via modeling and simulation. As previously demonstrated, a TDCS provides an effective interference suppression capability and differs from traditional spread spectrum systems in two primary ways: 1) spectrally crowded regions are avoided via adaptive spectral notching, and 2) no carrier modulation is employed; rather; "noise-like" basis functions are data modulated. Relevant TDCS research has unrealistically assumed perfect synchronization conditions, a vitally important and complete element of most digital communication systems. This research investigated initial TDCS acquisition performance for various synchronization codewords and several acquisition methods, e.g., direct time correlation (DTC) and German's technique, using both peak and threshold detection techniques. Theoretical development and MATLAB(R) simulation results indicate a TDCS can achieve a high probability of detection (P-D > 0.9) for relatively low input Signal-to-Noise Ratios (SNRs), as low as -23 dB for peak detection and -21 dB far threshold detection. For peak detection, DTC provides the best acquisition performance, i.e., the highest P-D for a given input SNR and fixed probability of false alarm, P-FA. For threshold detection with fixed P-FA of 0.01, DTC provides the best acquisition performance for SNRs below -12 dB, and German's technique provides the best acquisition performance above -12 dB. DTC results are shown to approximate matched filter performance while providing reasonable improvement over radiometric processing. Extensive computer simulations and subsequent analysis indicate that a TDCS cart adequately acquire and accurately align a locally generated reference waveform with a received noise-like TDCS signal.

Ku, J; Hunter, C T; Hunt, J P; Roberts, M L; Baker, C C; Lemasters, J J Author Information

Remote-handled transuranic nuclear waste poses a particular challenge for assaying due to the high neutron and γ-ray background that emanate from the non-fissile, but highly radioactive material, contained within the waste. The utilization of a Radio Frequency Quadrupole (RFQ) linac with a neutron flux of the order of 1010 n/s/4π has shown that, in principle, the differential die-away technique can be used to reliably assay this special class of nuclear waste.

The clinical efficacy of glycerine-ichthammol in otitis externa may be due to an anti-inflammatory action of ichthammol or a dehydrating effect of glycerine on the oedematous ear canal. Its antimicrobial activity, if any, against the common organisms in otitis externa is not well known. A study of the antibacterial property of glycerine-ichthammol as measured by a growth inhibition test and a modified cidal assay, showed inhibition of selected gram positive organisms (Streptococcus pyogenes and Staphylococcus aureus) by ichthammol and glycerine-ichthammol combination, but only negligible antibacterial activity against Pseudomonas aeruginosa and Escherichia coli. Candida albicans was also weakly inhibited. As the activity against gram negative organisms is minimal, incorporation of an anti-gram negative antibiotic such as gentamicin in the glycerine-ichthammol compound to enhance its antibacterial spectrum is suggested.

1. Dual‐excitation microfluorometry (Fura‐2 as indicator) was employed to monitor directly changes in the cytosolic calcium concentration [( Ca2+]i) in single cells. We investigated and compared the effects of stimulation of AR42J rat pancreatic acinar cells by two peptide agonists, substance P and bombesin. 2. Substance P (10(‐7) M) and bombesin (10(‐8) M) each gave rise to a marked, but transient, elevation in [Ca2+]i. The calcium signals evoked by the two peptides were qualitatively and quantitatively very similar. However, in the absence of extracellular Ca2+ the response to substance P, but not bombesin, was abolished. These results suggest that substance P induces calcium influx across the cell surface membrane but does not release calcium from internal stores. Bombesin in marked contrast releases calcium from intracellular stores in the absence of any detectable calcium influx. 3. Depolarization by high‐K+ extracellular solutions evoked a marked, but transient, rise in [Ca2+]i. This elevation in [Ca2+]i was strictly dependent upon the presence of Ca2+ in extracellular media. 4. Nifedipine (5 x 10(‐6) M), an antagonist of L‐type voltage‐dependent Ca2+ channels, blocked the elevations in [Ca2+]i induced by either substance P or high‐K+ solutions, but not that evoked by application of bombesin. 5. Patch‐clamp, single‐channel current recordings from cell‐attached patches of membrane confirmed the presence of voltage‐dependent calcium channels in the surface membranes of AR42J cells. Whole‐cell current recordings demonstrated voltage‐dependent inward Ca2+ (Ba2+) currents which were increased in amplitude by substance P and blocked by nifedipine. 6. The protein kinase C (PKC) activators, the phorbol diester, phorbol 1,2‐myristate 13‐acetate (PMA, 10(‐7) M), and cell‐permeable diacylglycerol analogues, 1‐oleoyl‐2‐acetyl‐sn‐glycerol (OAG, 2.5 x 10(‐6) M) and sn‐2‐dioctanoyl glycerol (DiC8, 2.5 x 10(‐6) M), mimicked the effect of substance P, but not bombesin, in elevating [Ca2+]i in a manner that was blocked by removal of extracellular Ca2+ or application of nifedipine. 7. The PKC inhibitor, polymyxin B (2.5 x 10(‐6) M), applied 2 min prior to stimulation blocked the effects of substance P and PKC activators, but not bombesin, in elevating [Ca2+]i. 8. The calcium signals evoked by substance P and bombesin are achieved by activation of different molecular mechanisms. Substance P, the evidence suggests, activates PKC which in turn stimulates calcium influx by opening voltage‐dependent Ca2+ channels in the cell surface membranes.(ABSTRACT TRUNCATED AT 400 WORDS)

High concentrations of bethanechol (10−4 to 10−3 M) were effective stimulants of amylase secretion from the mouse pancreas if incubations are performed in low [ca2+] (0.1 mM) solutions but not if normal Krebs solution (2.56 mM Ca2+) was used. This inhibitory effect of Ca2+ at high secretagogue concentrations did not appear to be mediated through the microtubules or microfilaments.

Segments of mouse parotid were placed in a superfusion chamber. Surface acini were impaled by one or two micro-electrodes for measurement of membrane potential and resistance. The acinus under investigation was stimulated by micro-iontophoretic application of acetylcholine (ACh) or adrenaline.

The effects of microiontophoretic applications of catecholamines and acetylcholine on parotid acinar cell membrane potential and resistance were investigated using intracellular microelectrode recording in superfused segments of mouse parotid or rat submandibular glands. Short pulses of acetylcholine and α-adrenergic agonists had similar effects, consisting of a marked decrease in membrane resistance accompanied by an initial depolarization or hyperpolarization depending on the level of the resting membrane potential. This initial response was followed by a slow hyperpolarization occurring at a time when the resistance was increasing towards the prestimulation level. The equilibrium potential for the initial potential change caused by excitation of the cholinergic receptors was investigated directly by setting the membrane potential at different levels by injecting direct current and stimulating the same cell repeatedly with equal doses of acetylcholine. The equilibrium potential was found to be about −55 mV. The delayed hyperpolarization could not be reversed by passing hyperpolarizing current, but actually increased in size with higher membrane potentials. The minimum latency of the effect of acetylcholine or α-adrenergic agonists was 200–500 msec.

In epoxidation of the conformationally biassed 5-t-butylcyclohex-2-enols by peroxybenzoic acid, higher cis-stereoselectivity and faster rate are found for the pseudo-equatorial than for the pseudo-axial alcohol. Cyclo-oct-2-en-1-ol is epoxidised with stereospecific introduction of the epoxy-group trans to hydroxy, and appropriate acyclic allylic alcohols show a preference for formation of the threo-epoxy-alcohol. A consistent interpretation of these results is advanced, based on the postulate that the preferred conformation of an allylic alcohol in the transition state for epoxidation is as in (XX).

AbstractBei der Epoxidation der Cyclohexenole (I) bzw. (IV) (oder deren Acetate) mit Peroxybenzoesäure zu den Produkten (II) und (III) bzw. (V) und (II) sind cis‐Stereoselektivität und Reaktionsgeschwindigkeit für den pseudo‐ äquatorialen Alkohol größer als für den pseudoaxialen.