Acoustic mismatch model and thermal phonon radiation across a tin/sapphire interface with radiation temperatures between 1.6 and 3.7 K

Using a special sandwich arrangement consisting of a constantan film, an insulating oxide layer and a superconducting tin-tunnel junction evaporated on an a-cut sapphire, the temperature jump between tin and sapphire has been measured as function of thermal phonon flux under steady-state and transient conditions using rectangular current pulses in the constantan heater. The tunnel junction serves as a very fast thermometer with a time resolution in the nanosecond range. During the steady-state and the heatup interval, full agreement is found between experimental results, and the predictions of the acoustic mismatch model applied to the phonon transfer across the tin/sapphire interface and under the additional assumption that thermal equilibrium exists between electrons and phonons (one-temperature model). In contrast, very strong deviations are found during the cooling process which starts immediately after the end of the heating pulses. This observed nonequilibrium between electron and phonon system is discussed in more detail in a subsequent paper.     

The cytoplasmic fragment of the aspartate receptor displays globally dynamic behavior

A number of cloned soluble fragments if the bacterial chemotaxis transmembrane receptors retain partial function. Prior studies of a fragment corresponding to the cytoplasmic domain (c-fragment) of the Escherichia coli aspartate receptor have correlated the signaling state of mutant receptors with the oligomerization state of the c-fragments: equilibria of smooth-swimming mutants are shifted toward oligomeric states; tumble mutants are shifted toward monomeric states [Long, D. G., & Weis, R. M. (1992) Biochemistry 31, 9904-9911]. We have applied several experimental probes of local and global structural flexibility to two signaling states, the wild-type (monomeric) and S461L smooth mutant (predominantly dimeric) c-fragments. Featureless near-UV CD spectra are observed, which indicate that the single Trp residue is in a symmetric environment (most likely averaged by fluctuations) and suggest that the C-termini of both proteins are highly mobile. Both proteins undergo extremely rapid proteolysis and enhance ANS fluorescence, which indicates that many sites are accessible to trypsin cleavage and hydrophobic sites are accessible to ANS binding. The global nature of the flexibility is demonstrated by 1H NMR studies. Lack of chemical shift dispersion suggests that fluctuations average the environments of side chains and backbone protons. Rapid exchange of 99% of the observable amide protons suggests that these fluctuations give high solvent accessibility to nearly the entire backbone. This evidence indicates that both monomeric and dimeric c-fragments are globally flexible proteins, with properties similar to "molten-globule" states. The significance of this flexibility depends on whether it is retained in functioning receptors: the c-fragment structure may lack important tertiary contacts, protein-protein interactions, or topological constraints needed to stabilize a nondynamic native structure, or the cytoplasmic domain of the native receptor may retain flexibility which may be modulated in the mechanism of transmembrane signaling.     

Correction to: Efficient Hardware Architectures for 1D- and MD-LSTM Networks

Journal of Signal Processing Systems -     

An improved extreme learning machine model for the prediction of human scenarios in smart homes

One of the main objectives of smart homes is healthcare monitoring and assistance, especially for elderly and disabled people. Therefore, an accurate prediction of the inhabitant behavior is very helpful to provide the required assistance. This work aims to propose a prediction model that satisfies the accuracy as well as the rapidity of the learning phase. To do so, we propose to improve the existing extreme learning machine (ELM) model by defining a recurrent form. This form ensures a temporal relationship of inputs between observations at different time steps. The new model uses feedback connections to the input layer from the output layer which allows the output to be included in the long-term prediction. A recurrent dynamic network, with feedback connections of the output of the network, is proposed to predict the future series representing future activities of the inhabitant. The resulting model, called Recurrent Extreme Learning Machine (RELM), provides the ability to learn the human behavior and ensures a good balance between the learning time and the prediction accuracy. The input data is based on the real data representing the activities of persons belonging to the profile of first level (i.e. P ₁) as measured by the dependency model called Functional Autonomy Measurement System (SMAF) used in the geriatric domain. The experimental results reveal that the proposed RELM model requires a minimum time during the learning phase with a better performance compared to existing models.     

Assessment of pollution aerosols sources above the Straits of Dover using lead isotope geochemistry.

We assess the capability of lead isotopes to study the transport of pollution aerosols above the Straits of Dover by collecting atmospheric aerosols above the Eastern Channel and the Southern Bight of the North Sea. During the same period, we characterized the lead isotopic signature of the main industrial sources on the French coast near the Straits of Dover. Urban and automobile-derived aerosols were also collected. Due to the phasing out of lead in gasoline, the urban isotopic composition (206Pb/207Pb = 1.158 +/- 0.003) has become more radiogenic, although it is highly variable. On a regional scale, major industrial emissions have a well-defined isotopic composition (1.13 < 206Pb/207Pb < 1.22), more radiogenic than the petrol-lead signature (1.06 < 206Pb/207Pb < 1.12). These results together with those measured near the main coastal highway show that the automobile source has become a minor component of particulate lead in air. On a local scale, Dunkerque, the most urbanized and industrialized area along the Straits of Dover, may transiently control elevated lead concentrations. Except for the occurrence of local and regional range transport episodes, lead concentrations in the Straits of Dover can be related to remote or semi-remote pollution source emissions. Combining air mass retrospective trajectories and related lead abundances and isotopic compositions, it can be shown that lead aerosols originating from eastern Europe have an isotopic signature (1.145 < 206Pb/207Pb < 1.169) different from the isotopic composition of west-European lead aerosols (1.111 < 206Pb/207Pb < 1.142). The influence of remote North American sources is suggested, with caution, due to uncertainties in meteorological calculations.     

Thermionic emission model for contact resistance in organic field-effect transistor

Injection mechanism of top-contact pentacene field-effect transistor (OFET) was investigated in respect to the internal field. The contact resistance was evaluated by the transmission line method for various applied external voltages as well as various pentacene film thicknesses. The behaviour of contact resistance was described in terms of the thermionic emission model (Schottky injection) and internal electric field generated by excess charges accumulated on pentacene–gate insulator interface. It was shown that pentacene film thickness changes the internal electric field affecting the carrier injection barrier. It was concluded that the space-charge field effect made a significant contribution for smaller pentacene film thicknesses and therefore in accordance to the thermionic model was able to decrease contact resistance representing the potential drop.     

Contact Behavior of Microcrystalline Cellulose Pellets Depending on their Water Content

Microcrystalline cellulose pellets for oral drug delivery are often produced by a combined wet extrusion-spheronization process. During the entire process, the cylindrical as well as the spherical pellets are exposed to various stresses resulting in a change of their shape and size due to plastic deformation and breakage. In this work, the effect of moisture content of pellets on their mechanical behavior is studied. In static compression tests, the strong influence of water content on deformation behavior of pellets is confirmed. Moreover, impact tests are performed using a setup consisting of three high-speed cameras to record pellet-wall collisions. Material properties, such as stiffness, restitution coefficient, breakage force, and displacement, were analyzed depending on the water content.     

Morphological and rheological detection of the phase inversion of PMMA/PS polymer blends

The phase inversion process was investigated from different points of view. First, a reliable on-line and off-line method of morphology detection using light microscopy is established. The method provides fast information that can be used to discriminate between different types of morphologies. Second, TEM images are modelled with Markov Random Fields. For characterization purposes image features are introduced and tested. A combination of features allows classification of different morphologies of PMMA/PS blends. In the third part we show that the rheological properties of blends allow also discrimination between different morphologies. Received: 6 November 1997/Revised version: 3 December 1997/Accepted: 3 December 1997     

Electrochemical methods coupled with impedance measurement for energy gap study: correlation between the energy states and charge transport properties

The energy states of poly(3-hexylthiophene) (P3HT) polymer films degraded using UV/ozone environment were studied by optical and electrochemical methods. Energy levels of highest occupied and lowest unoccupied molecular orbitals as well as localized states between them were estimated. Electrical properties of polymer films sandwiched between two metal electrodes were investigated for various trap energy distributions. Comparison of the energy states density evaluated by optical/electrochemical methods and estimated from the current-voltage characteristics was carried out to discuss suitability of space-charge limited electrical conduction models for semiconducting polymers.     

A Diversified Library of Bacterial and Fungal Bifunctional Cytochrome P450 Enzymes for Drug Metabolite Synthesis

Innovative biohydroxylation catalysts for the preparation of drug metabolites were developed from scratch. A set of bacterial and fungal sequences of putative and already known bifunctional P450 enzymes was identified by protein sequence alignments, expressed in Escherichia coli and characterised. Notably, a fungal self‐sufficient cytochrome P450 (CYP) from Aspergillus fumigatus turned out to be especially stable during catalyst preparation and application and also in presence of organic co‐solvents. To enhance the catalytic activity and broaden the substrate specificity of those variants with high expression levels prominent single mutations were introduced. Selected improved variants were then used as lyophilised bacterial lysates for the synthesis of 4′‐hydroxydiclofenac and 6‐hydroxychlorzoxazone, the two metabolites of active pharmaceutical compounds diclofenac and chlorzoxazone representing the same metabolites as generated by human P450s.