Design and implementation of multipattern generators in analog VLSI

In recent years, computational biologists have shown through simulation that small neural networks with fixed connectivity are capable of producing multiple output rhythms in response to transient inputs. It is believed that such networks may play a key role in certain biological behaviors such as dynamic gait control. In this paper, we present a novel method for designing continuous-time recurrent neural networks (CTRNNs) that contain multiple embedded limit cycles, and we show that it is possible to switch the networks between these embedded limit cycles with simple transient inputs. We also describe the design and testing of a fully integrated four-neuron CTRNN chip that is used to implement the neural network pattern generators. We provide two example multipattern generators and show that the measured waveforms from the chip agree well with numerical simulations.     

Cloning, expression, and characterization of a DNA binding domain of gpNu1, a phage lambda DNA packaging protein

Terminase is an enzyme from bacteriophage lambda that is required for insertion of the viral genome into an empty pro-capsid. This enzyme is composed of the viral proteins gpNu1 (20.4 kDa) and gpA (73.3 kDa) in a holoenzyme complex. Current models for terminase assembly onto DNA suggest that gpNu1 binds to three repeating elements within a region of the lambda genome known as cosB which, in turn, stimulates the assembly of a gpA dimer at the cosN subsite. This prenicking complex is the first of several stable nucleoprotein intermediates required for DNA packaging. We have noted a hydrophobic region within the primary amino acid sequence of the terminase gpNu1 subunit and hypothesized that this region constitutes a protein-protein interaction domain required for cooperative assembly at cosB and that is also responsible for the observed aggregation behavior of the isolated protein. We therefore constructed a mutant of gpNu1 in which this hydrophobic "domain" has been deleted in order to test these hypotheses. The deletion mutant protein, gpNu1DeltaK, is fully soluble and, unlike full-length protein, shows no tendency toward aggregation; However, the protein is a dimer under all experimental conditions examined as determined by gel permeation and sedimentation equilibrium analysis. The truncated protein is folded with evidence of secondary and tertiary structural elements by circular dichroism and NMR spectroscopy. While physical and biological assays demonstrate that gpNu1DeltaK does not interact with the terminase gpA subunit, the deletion mutant binds with specificity to cos-containing DNA. We have thus constructed a deletion mutant of the phage lambda terminase gpNu1 subunit which constitutes a highly soluble DNA binding domain of the protein. We further propose that the hydrophobic amino acids found between Lys100 and Pro141 define a self-association domain that is required for the assembly of stable nucleoprotein packaging complexes and that the C-terminal tail of the protein defines a distinct gpA-binding site that is responsible for terminase holoenzyme formation.     

Erwinia amylovora secretes DspE, a pathogenicity factor and functional AvrE homolog, through the Hrp (type III secretion) pathway

Erwinia amylovora was shown to secrete DspE, a pathogenicity factor of 198 kDa and a functional homolog of AvrE of Pseudomonas syringae pv. tomato. DspE was identified among the supernatant proteins isolated from cultures grown in an hrp gene-inducing minimal medium by immunodetection with a DspE-specific antiserum. Secretion required an intact Hrp pathway.     

Wärmeübertragung in dissoziierenden Gasen bei schneller und gehemmter Gleichgewichtseinstellung

Stoff- und Transporteigenschaften von dissoziierenden Oasen: Spezifische Wärme, Wärmeleitzahl, Enthalpie, Viskosität, Diffusionskoeffizient. Aufstellung von Grenzschicht-Differentialgleichungen dissoziierender Gase für die Wärmeübertragung bei schneller Gleichgewichtseinstellung. Versuche zur Wärmeübertragung bei schneller Gleichgewichtseinstellung am N₂O₄–NO₂-Gemisch und deren Ergebnisse. Wärmeübertragung bei gehemmter Gleichgewichtseinstellung mit fallendem Druck. Ergebnisse für natürliche und erzwungene Konvektion am horizontalen Zylinder.     

Die Erhöhung der Grundfrequenz und der Beullast von Kreisplatten durch geeignete plastische Verformung

Zusammenfassung Eine M?glichkeit, ohne Mehraufwand an Material oder Verwendung teurerer Werkstoffe das dynamische Verhalten oder die Tragf?higkeit von Bauteilen zu verbessern, wird am Beispiel der Grundfrequenz- und Beullaststeigerung von Kreisplatten durch das Einpr?gen von geeigneten Eigenspannungszust?nden dargelegt. Die Ergebnisse einer Optimierung solcher Eigenspannungsfelder werden dargestellt, und die M?glichkeit der Erzeugung geeigneter Eigenspannungszust?nde wird an Hand eines Experiments nachgewiesen.     

Neutralizing Coal Mine Effluent with Limestone to Decrease Metals and Sulphate Concentrations

Abstract.   This paper describes pilot scale tests of a novel process for the neutralisation of acidic mine water. Leachate from a waste coal dump was neutralised with limestone, and iron, aluminium, and sulphate were removed. Specific aspects studied were: the process configuration; the rates of iron oxidation, limestone neutralisation, and gypsum crystallisation; the chemical composition of the effluents before and after treatment; the efficiency of limestone utilisation; and the sludge solids content. The acidity was decreased from 12,000 to 300 mg/L (as CaCO₃), sulphate from 15,000 to 2,600 mg/L, iron from 5,000 to 10 mg/L, aluminium from 100 to 5 mg/L, while the pH increased from 2.2 to 7.0. Reaction times of 2.0 and 4.5 h were required under continuous and batch operations respectively for the removal of 4 g/L Fe (II). The iron oxidation rate was found to be a function of the Fe (II), hydroxide, oxygen, and suspended solids (SS) concentrations. The optimum SS concentration for iron oxidation in a fluidised-bed reactor was 190 g/L. Up-flow velocity had no influence on the rate of iron oxidation in the range 5 to 45 m/h. Sludge with a high solids content of 55% (m/v) was produced. This is high compared to the typical 20% achieved with the high density sludge process using lime. It was determined that neutralisation costs could be reduced significantly with an integrated iron oxidation and limestone neutralisation process because limestone is less expensive than lime, and a high-solids-content sludge is produced. Full scale implementation followed this study.     

(31)P-MR Spectroscopy for the evaluation of energy metabolism in intact residual myocardium after acute myocardial infarction in humans

Objective experimental studies have demonstrated that acute myocardial infarction (MI) alters energy metabolism even in non-infarcted adjacent tissue. In patients with subacute MI, the influence of the regional ischemie insult on energy metabolism of intact septal myocardium was analyzed using³¹P-Magnetic resonance spectroscopy (MRS). Patients and Methods in eight patients with wall motion abnormalities in the anterior wall³¹P-spectra were obtained from non-infarcted adjacent scptal myocardium, as well as infarcted anterior myocardium (voxel size 25 ccm each) 29 ±8 days after MI using a 3D-CSI technique. Additionally, cardiac function was analyzed using breath-hold cine MRI. MR1 was repeated 6 months after revascularization to assess viability of infarcted segments. Eight age-matched healthy volunteers served as control group. Results according to follow-up MRI 4/8 patients showed regional wall motion recovery. Here, PCr/ATP-ratios were not significantly reduced in intact septal myocardium as well as infarcted anterior myocardium compared to healthy volunteers (1.28 ±0.10 and 1.14 ±0.09 vs. 1.45 ±0.29). No recovery of regional function was detected in 4/8 patients with —therefore—non-viable anterior myocardium. PCr/ATP-ratios were significantly reduced in intact and infarcted myocardium compared with healthy volunteers as well as to patients with wall motion recovery (0.77 ±0.17 and 0.49 ±0.23;P < 0.05). Discussion these preliminary results indicate that energy metabolism is reduced in patients with persisting wall motion abnormalities after myocardial infarction and revascularization in ischemically injured as well as in adjacent non-injured myocardium.     

Second Generation Nanostructured Metal Oxide Matrices to Increase the Thermal Stability of CO and NO2 Sensing Layers Based on Iron(II) Phthalocyanine

An iron(II) phthalocyanine (FePc) complex solubilized by decylamine (DA) and benzylamine (BA) is incorporated into a nanoparticulate metal oxide matrix to develop optical sensor films sensitive to NO₂ and CO. Eleven amine solvents have been tested as N‐donor ligands that permit ligand exchange with the gas molecules. We have systematically investigated the suitability of different N‐donor ligands, studied the thermal stability of the NO₂‐ and CO‐sensing films at 4, 25, 60, and 80 °C by photometry, and corroborated our findings by using NMR experiments. A satisfactory thermal stability of the films has not been obtained for chemically unmodified nanoparticulate metal oxide matrices. We have therefore developed a second generation of nanostructured metal oxide supports that show increased thermal stability and adequate sensitivity to NO₂ and CO. These novel nanostructured matrices have been chemically modified using amines, alumina oligomers, and/or anti‐gas‐fading agents. These components have been integrated into the metal oxide matrices to avoid degradation of the optical films and to preserve their sensitivity.