The relevance of somatostatin receptors in thyroid neoplasia

111In-octreotide scintigraphy in patients with persistent medullary thyroid carcinoma (MTC) visualized tumors in about half of the surgically explored sites. Tumor visualization correlated with rapid tumor growth and large tumor volume as judged from calcitonin levels. The 111In concentration ratio between tumor (T) and blood (B) in surgically excised lymph node metastases of MTC showed a large variation, with low values for microscopic and high values for macroscopic metastases in individual patients. Three cases of MTC, Hürthle cell adenoma and papillary thyroid cancer are reported with preoperative scintigraphy, T/B ratios and Northern analyses of the surgical biopsies. Visualization of tumors was possible in the absence of sstr2 (the high affinity receptor for octreotide) with the exception of microscopic tumor growth. T/B values in the patient with Hürthle cell adenoma were similar to those found in the contralateral thyroid lobe with goitre. The relatively high uptake of 111In in benign thyroid conditions probably limits the use of octreotide scintigraphy in the diagnosis of primary tumors. The technique has certain advantages over radioiodine scintigraphy after the surgical treatment of thyroid tumors: no need for withdrawal of thyroxin substitution; a possibility to diagnose metastases of tumors that do not concentrate radioiodine (MTC, Hürthle cell cancer); and complementary information about metastatic sites of non-medullary thyroid cancer (papillary and follicular tumors).     

A New Constitutive Model for the Finite Element Simulation of Local Hot Forming of Aluminum 6xxx Alloys

A new internal variable constitutive model for the use in finite element (FE) simulation of local hot forming of 6xxx aluminum alloys is presented. The model relates the flow stress to the temperature, total strain rate, and internal variables, which represent the dislocation density and the contributions to the hardening stress from elements in solid solution and precipitates. The time evolutions of the internal variables are modeled by an equation representing the accumulation/annihilation of dislocations and by a precipitate model developed elsewhere, taking into account a size distribution of precipitates. The parameters of the constitutive model have been fitted to tensile tests at different temperatures, strain rates, and precipitate states. Manuscipt submitted March 22, 2007.

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Synchronization in a network of identical discrete‐time agents with uniform constant communication delay

This paper studies the synchronization problem for a network of identical discrete‐time agents with unknown uniform constant communication delay. When the agents are non‐introspective, the problem is solvable via a decentralized low‐gain‐based synchronization controller if the delay satisfies the proposed upper bound. When the agents are introspective, the synchronization problem can be solved with arbitrary bounded communication delay. Copyright © 2013 John Wiley & Sons, Ltd.     

Method of data reduction of sampled speech signals by using nonuniform sampling and a time-variable digital filter

A method of data reduction applicable to sampled continuous signals, for example, sampled speech signals, is described and tested by computer simulation, Nonuniform sampling obtained through skipping of samples is used. The reconstruction network is a time-variable digital filter. A minimisation procedure for coefficient derivation is described.     

Some related aspects of platypus electroreception: temporal integration behaviour, electroreceptive thresholds and directionality of the bill acting as an antenna

This paper focuses on how the electric field from the prey of the platypus is detected with respect to the questions of threshold determination and how the platypus might localize its prey. A new behaviour in response to electrical stimuli below the thresholds previously reported is presented. The platypus shows a voluntary exploratory behaviour that results from a temporal integration of a number of consecutive stimulus pulses. A theoretical analysis is given, which includes the threshold dependence on the number of receptors and temporal integration of consecutive stimuli pulses, the close relationships between electrical field decay across the bill, electroreceptive thresholds and directionality of the platypus bill acting as an antenna. It is shown that a lobe shape, similar to that which has been measured, can be obtained by combining responses in a specific way from receptors sensing the electric field decay across the bill. Two possible methods for such combinations are discussed and analysed with respect to measurements and observed behaviour of the platypus. A number of factors are described which need to be considered when electroreceptive thresholds are to be determined. It is shown that some information about the distance to the source is theoretically available from the pattern of field decay across the platypus's bill. The paper includes a comparative analysis of radar target tracking and platypus prey localization.     

Almost output synchronization for heterogeneous time‐varying networks for a class of non‐introspective,nonlinear agents without exchange of controller states

We consider almost output synchronization for directed heterogeneous time‐varying networks where agents are non‐introspective (i.e., agents have no access to their own states or outputs) in the presence of external disturbances. The nonlinear agents have a triangular structure and are globally Lipschitz continuous. The network can be time‐varying with network switches occurring at arbitrary moments. A purely decentralized time‐invariant protocol based on a low‐gain and high‐gain method is designed for each agent to achieve almost output synchronization while reducing the impact of disturbances on the output synchronization error. Copyright © 2016 John Wiley & Sons, Ltd.     

Non-k-Diagonality in the Interlayer Pair-Tunneling Model of High-Temperature Superconductivity

We investigate the effect of k-space broadening of the interlayer pairing kernel on the critical temperature T_c and the k-dependence of the gap function in a one-dimensional version of the interlayer pair-tunneling model of high-T_c superconductivity. We consider constant as well as k-dependent intralayer pairing kernels. We find that the sensitivity to k-space broadening is larger the smaller the width of the peak of the Fermi-level gap calculated for zero broadening. This width increases with the overall magnitude of the interlayer tunneling matrix element, and decreases with the bandwidth of the single-electron intralayer excitation spectrum. The width also increases as the Fermi level is moved towards regions where the excitation spectrum flattens out. We argue that our qualitative conclusions are valid also for a two-dimensional model. This indicates that at or close to half-filling in two dimensions, when the Fermi-surface gap for zero broadening attains its peaks at (±/a, 0) and (0, ±/a) where the excitation spectrum is flat, these peaks should be fairly robust to moderate momentum broadening.