Charakterisierung pankreatischer Casein-Plasteine

Characterization of pancreatic casein plasteins. In the course of the plastein reaction hydrophobic peptides concentrate mainly in the aggregates (plasteins), whilst hydrophilic peptides remain in solution (supernatant). Liquid chromatographic and sequence analytical studies of pancreatic casein plasteins have shown that the aggregates consist mainly of the free amino acids tyrosine, phenylalanine and tryptophan. Plasteins contain, in addition, short-chain peptides, particularly from the C-terminal of β-casein. Characterization of the functional properties of the plasteins has shown clearly that aggregation of the short-chain peptides and free amino acids is brought by non-covalent, hydrophobic and ionogenic interactions. In the supernatants resulting from the plastein reaction caseinophosphopeptide sequences, in particular from α_s-casein, were determined.     

Aggregate input-output models of neuronal populations

An extraordinary amount of electrophysiological data has been collected from various brain nuclei to help us understand how neural activity in one region influences another region. In this paper, we exploit the point process modeling (PPM) framework and describe a method for constructing aggregate input-output (IO) stochastic models that predict spiking activity of a population of neurons in the "output" region as a function of the spiking activity of a population of neurons in the "input" region. We first build PPMs of each output neuron as a function of all input neurons, and then cluster the output neurons using the model parameters. Output neurons that lie within the same cluster have the same functional dependence on the input neurons. We first applied our method to simulated data, and successfully uncovered the predetermined relationship between the two regions. We then applied our method to experimental data to understand the input-output relationship between motor cortical neurons and 1) somatosensory and 2) premotor cortical neurons during a behavioral task. Our aggregate IO models highlighted interesting physiological dependences including relative effects of inhibition/excitation from input neurons and extrinsic factors on output neurons.     

Evaluation of colour properties and chemical quality parameters of cactus juices

The chemical composition and visual appearance of cactus fruits from the genera Opuntia and Hylocereus were investigated. Colour properties were assessed in solutions with pH ranging from 1 to 8 and expressed as chroma, hue and colour shade. Between pH 3 and 7, all samples were stable as indicated by hue and chroma values. The colour shade of the red juice of Opuntia ficus-indica cv. 'Rossa' was in the range of red beet preparations hitherto most commonly used for colouring low-acid food commodities. Hylocereus was characterized by purplish hues, whereas the juice from O. ficus-indica cv. 'Gialla' displayed a yellow tonality. An improved spectrophotometric method for pigment quantification was proposed. Betacyanin contents were 525.3, 73.9 and 1.3 mg/l in juices from Hylocereus polyrhizus, Opuntia ficus-indica cv. 'Rossa' and O. ficus-indica cv. 'Gialla', whereas betaxanthins amounted to 48.3, 36.4 and 5.3 mg/l in O. ficus-indica cv. 'Gialla', O. ficus-indica cv. 'Rossa', and H. polyrhizus, respectively. Although the colourless fruits from O. ficus-indica cv. 'Bianca' and H. undatus could not be considered as a colour source, selected quality parameters were also investigated with respect to their nutritional value. To the best of our knowledge, this is the first report about the chemical quality parameters of H. polyrhizus and H. undatus.     

Quasistatics,Ollendorff-Cerenkov electrodynamics and moving media

Contents The quasistatic approach to engineering problems implies an infinite phase velocity of a plane wave of light in vacuum; on the other hand, a self-consistent theory of electrodynamics of moving media is based upon the constant, finite velocity c of such a wave. — A suggestion is made — with the aid of the Ollendorff approach to electrodynamics of moving media — how the two conflicting points of view may be reconciled.

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Quasistatik, Ollendorff-Cerenkov Elektrodynamik und bewegte Körper

Übersicht Die quasistatische Elektrodynamik macht Gebrauch von der Annahme einer unendlich großen Vakuum-Phasengeschwindigkeit der ebenen elektromagnetischen Welle; die Elektrodynamik bewegter Körper hingegen beruht auf der Annahme einer endlichen Fortpflanzungsgeschwindigkeit c. —Ein Vorschlag wird gemacht — an Hand der Ollendorff-Elektrodynamik — zur Beseitigung des entstehenden Widerspruchs.

     

Purification and crystal growth of LiY0.5Er0.5F4 crystals

The purification procedure of the LiY_0.5Er_0.5F₄ compound for Bridgman-Stockbarger and Czochralski single crystal growth has been investigated. Yttrium and rare-earth oxyfluorides were found to form during hydrofluoric heat-treatment of the starting fluoride mixture. Optically clear single crystals of purified LiY_0.5Er_0.5F₄ were grown by both Bridgman-Stockbarger and Czochralski methods. The stoichiometry was investigated by magnetic susceptibility measurements and the Er content in the single crystals grown by both Bridgman-Stockbarger and Czochralski methods were found to fit stoichiometry within the measurement error. No free (OH)^? ions were found by infrared absorption spectroscopy.     

Shielding Performance of Metallic Cylinders

Electrical and electronic equipment must often be protected against external interference. Accordingly, metal shields are used against microwave radiation, electromagnetic effects, etc. Conducting materials, impregnated with elastic substances, are also used in many cases. The present paper deals with the performance of such a cylindrical shield, including a reference to shielding effectiveness. It is shown that with the assumed model the shield is pervious along its axis over a spectrum of frequencies.     

Resource optimization in QoS multicast routing of real-time multimedia

We consider a network design problem, where applications require various levels of Quality-of-Service (QoS) while connections have limited performance. Suppose that a source needs to send a message to a heterogeneous set of receivers. The objective is to design a low-cost multicast tree from the source that would provide the QoS levels (e.g., bandwidth) requested by the receivers. We assume that the QoS level required on a link is the maximum among the QoS levels of the receivers that are connected to the source through the link. In accordance, we define the cost of a link to be a function of the QoS level that it provides. This definition of cost makes this optimization problem more general than the classical Steiner tree problem. We consider several variants of this problem all of which are proved to be NP-Hard. For the variant where QoS levels of a link can vary arbitrarily and the cost function is linear in its QoS level, we give a heuristic that achieves a multicast tree with cost at most a constant times the cost of an optimal multicast tree. The constant depends on the best constant approximation ratio of the classical Steiner tree problem. For the more general variant, where each link has a given QoS level and cost we present a heuristic that generates a multicast tree with cost O(min{logr,k}) times the cost of an optimal tree, where r denotes the number of receivers, and k denotes the number of different levels of QoS required. We generalize this result to hold for the case of many multicast groups.     

Charge relaxation across conducting films

Contents A brief analysis of the charge relaxation mechanism across a nonmagnetic metallic film was outlined. In the relatively recent past the classical relaxation time estimates for a bulk conductor were reexamined and found wanting; although for semiconductors the classical approach is still sometimes resorted to for a rough working estimate, we adopted in the present communication a somewhat different, quasi-heuristic study, explicitly taking into account the distributed parameter characteristics of the film. The solution of the proposed problem also provides insight into the transient behavior of nonmagnetic shielding plates-insight which might be of practical value in the area of electromagnetic compatibility.

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Ladungsrelaxation in leitenden Schichten

Übersicht Es wird eine kurze Analyse des Mechanismus' der Ladungsrelaxation in einer nichtmagnetischen, metallischen Schicht vorgestellt. Die vor relativ kurzer Zeit wieder untersuchte Abschätzung der klassischen Relaxationszeit für ausgedehnte Leiter ließ zu wünschen übrig. Obwohl man sich bei Halbleitern für eine grobe Abschätzung manchmal noch des klassischen Ansatzes bedient, wurde in der vorliegenden Mitteilung eine davon abweichende quasi-heuristische Betrachtung verwendet, wobei die verteilten Parameter der Schicht explizit berücksichtigt werden. Die Lösung das vorgelegten Problems verschafft auch Einsicht in des transiente Verhalten nichtmagnetischer Abschirmplatten; dies kann auf dem Gebiet der Elektromagnetischen Verträglichkeit von praktischem Wert sein.

     

Phenolic compounds and antioxidant capacity of Brazilian mango (Mangifera indica L.) varieties

Phenolic compounds and antioxidant activities of four mango varieties cultivated in Brazil were analyzed. The profile of flavonol-O-glycosides and xanthone-C-glycosides was characterized in pulps from Haden, Tommy Atkins, Palmer, and Ubá cultivars and in the agro-industrial residues from Ubá variety by LC–ESI–MS analysis. The first three varieties were collected from conventional production, whereas Ubá was obtained from organic production. The total phenolic content of the peels and seed kernel extracts was analyzed utilizing Folin-Ciocalteu’s reagent. The aqueous-methanolic extracts of pulp, peel and seed kernels were analyzed for antioxidant activity (AA) by free radical-scavenging and reducing power. A total of 12 flavonoids and xanthones were identified in the pulps, peels and seed kernels, with larger amounts of these compounds being present in the organically grown Ubá variety. The Ubá mango pulp presented higher AA and the peel and seed kernel extracts showed higher AA than did a commercial standard.