Monte Carlo simulation of the glass transition in three-dimensional dense polymer melts

1993

Abstract We determine the incoherent intermediate scattering function φsq(t) for a three-dimensional dense polymer melt. This function shows the signature of a two-step process which was quantitatively compared to the idealized mode coupling theory (MCT) within the β-relaxation regime. A major result of this analysis is that the studied temperature interval splits in a high temperature part, where the idealized theory describes φsq(t) over about three decades in time, and a low temperature part, where it strongly overestimates the freezing tendency of the melt. Since one can qualitatively attribute this discrepancy between the idealized MCT and the simulation data to hopping processes, the …

Enzymatic Activity of CD26 (Dipeptidylpeptidase IV) is not Required for Its Signalling Function in T Cells

1993

Abstract CD26 is a proteolytic enzyme (dipeptidylpeptidase IV) expressed on the T cell surface that defines an alternative activation signal for human T lymphocytes. Crosslinking of CD26 via monoclonal antibodies triggers proliferation and cytotoxicity in preactivated T cells. In this study, we used highly specific competitive and irreversible inhibitors of dipeptidylpeptidase IV to study the role of the enzymatic activity in activation of CD26- transfected T cells as well as of CD26-expressing normal human T cell clones. These inhibitors at concentrations that blocked up to 95% of the enzymatic activity, did not specifically inhibit T cell activation neither via TCR/CD3 nor via CD26 itself…

Deceleration of antiprotons from MeV to keV energies

1993

Trapping of antiprotons for high precision measurements at the Low Energy Antiproton Ring (LEAR/CERN) requires the deceleration of the antiproton beam from typically 5.8 MeV energy down to 10 keV for final capture in standard Penning traps. Two methods, the degradation of the beam in thin foils and the deceleration of the beam in an inverse cyclotron are investigated so far. The foil technique was successfully demonstrated with trapping efficiencies up to a few 10−4 and is now routinely used in the high precision measurement of the antiprotonproton mass ratio. The degradation foil method is compared with the deceleration technique using an inverse cyclotron tested also at LEAR.

Sesquiterpene lactones from iranian Artemisia species

1993

Abstract The aerial parts of Artemisia turcomanica and A. deserti yielded two new germacranolides, a new guaianolide, and several known mono- and sesquiterpenes.

Deep-water stromatolites andFrutexites Maslov from the early and Middle Jurassic of S-Germany and Austria

1993

Despite extensive discussions during the last 20 years stromatolites are still used by many geologists as unequivocal indicators of very shallow-water conditions. We investigated four stratigraphic units from the Lower and Middle Jurassic of southern Germany (Posidonien-Schiefer, Amaltheen-Ton) and of the Northern Calcareous Alps (Adneter Kalk, Klauskalk), which were formerly interpreted as shallow marine sediments by some authors due to the occurrence of stromatolites. Our interpretations of the macro-, micro- and ultrafacies of these sediments are not compatible with shallow-water settings. We therefore propose a deep-marine, aphotic origin of these stromatolites. Former interpretations o…

Evidence for sex pheromones produced by males and females inBlatta orientalis (Dictyoptera, Blattidae).

1993

Males and females ofBlatta orientalis produce a volatile sex pheromone attractive at a distance. The male initiates courtship behavior by adopting a calling posture while emitting his sex pheromone. He exposes the anterior region of his tergites by stretching his abdomen horizontally. Morphological observations show the existence of male tergal glands on the anterior region of tergites 1 to 8. Behavioral assays of females utilizing methylene chloride extracts of various male body parts reveal that extracts of the anterior region of tergites are highly attractive and induce more positive responses that any other body part. Once near the male, the attracted female opens widely her genital atr…

A comparative study of the population pharmacokinetics of gentamicin and amikacin in newborn patients

1993

SUMMARY The population kinetics of gentamicin and amikacin were studied comparatively in newborn patients with a similar range of gestation age (37.9 ± 2.9 and 36.7 ± 3.6 weeks), postnatal age (13.8 ± 7.4 and 16.7 ± 7 days) and weight (2.85 ± 0.57 and 2.72 ± 0.75 kg), undergoing routine therapeutic monitoring of their serum levels. Individual kinetic analysis of serum drug levels was done using a single-compartment model. The population model employed assumes the existence of residual variability in the serum concentrations and interindividual variability in the pharmacokinetic parameters. The clearance and the apparent distribution volume were calculated for each patient using a two-stage …

?-Carotene Supplements Cannot Meet All Vitamin A Requirements of Vitamin A-Deficient Rats

1993

Dynamical properties of the sleep EEG in different frequency bands.

1993

The information concerning the dynamic behavior of the sleep process gained by the usual evaluation of sleep EEGs according to the criteria of Rechtschaffen and Kales is limited. Therefore a new methodical approach is presented, which is a special case of spectral analyzed data processing. After digital band-pass filtering of the sleep EEG the root-mean-square (RMS) value of successive 20 s EEG epochs is calculated in defined frequency ranges. This procedure ensures to take into account the influence of the phase relation between different frequency components. The temporal course of these RMS values during the night reveals smooth curves with continuous transitions between different sleep …

Simultaneous bilateral occurrence of a M. extensor digiti medii and a M. extensor digitorum brevis.

1993

Summary For the first time, the simultaneous and bilateral occurrence of two variants of the extensors of the fingers, M. extensor digiti medii and M. extensor digitorum brevis, is reported. The extensor of the middle finger arises from the distal fourth of the radius and runs to the base of the proximal phalanx. The short extensor of the fingers arises from the metacarpal region and inserts into the dorsal aponeurosis. Both muscles are innervated by the R. profundus n. radialis.

Relation between reflectance of rice crop and indices of pollution by heavy metals in soils of albufera natural park (Valencia, Spain)

1993

13 páginas, 3 figuras, 4 tablas, 1 foto.

Glycosaminoglycan Antibodies in Endocrine Ophthalmopathy

1993

An increased accumulation of glycosaminoglycans (GAG) in the orbita has been reported in endocrine ophthalmopathy (EO). In this study we investigated whether antibodies directed against GAG are present in the sera of 52 EO patients and 47 healthy controls. Three out of 52 patients exhibited low titers of antinuclear antibodies and all patients were negative for antibodies against extractable nuclear antigens. Isotype IgG antibodies were detected by means of an ELISA using hyaluronic acid and dermatan sulfate as antigens. Values were expressed as optical density at 405 nm. In comparison to the control group (0.445, 0.364, 0.588; median, 25th, 75th percentile) significantly (p < 0.001) higher…

Lifetime measurements of the 3D3/2 and 3D5/2 metastable states in CaII

1993

The lifetime of the metastable 3D3/2 and 3D5/2 states of Ca+ ions is determined in a r.f. ion trap by laser excitation of this levels and subsequent time delayed probing of the state population by a second laser. In a buffer gas atmosphere of about 10−5−10−6 mbar of He we observe quenching to the ground state and strong finestructure mixing of the two D-states. This mixing allowes only the determination of the combined lifetime. Our result of τ(3D)=1.24(39) s is in good agreement with theoretical calculations.

Focal myositis of the temporal muscle

1993

Focal myositis is a rare inflammatory disease of the skeletal muscle that may involve any part of the body. We present a 19-year-old man with a short history of a painful pseudotumor in the right temporal region. MRI pictures showed a swollen right temporal muscle and muscle biopsy revealed the characteristic histological and immunocytochemical findings of polymyositis.

Kinetic-Ising-model description of Newtonian dynamics: A one-dimensional example.

1993

We show that the Newtonian dynamics of a chain of particles with an anharmonic on-site potential and harmonic nearest-neighbor interactions can be described by a one-dimensional kinetic Ising model with most general Glauber transition rates, provided the temperature is low enough compared to the minimum barrier height. The transition rates are calculated by use of the transition-state theory. At higher temperatures, memory effects occur which invalidate this kinetic description. These memory effects are due to the appearance of dynamically correlated clusters of particles performing periodic oscillations over a certain time scale.

Neurilemoma of the tibial nerve in the popliteal fossa A case report

1993

We report a case of a 61 year old man who had a history of 4 years right leg pain. Clinical and radiological examination and MRI revealed a soft tissue mass in the popliteal fossa. A neurilemoma of the tibial nerve was confirmed after removal of the tumor and histological examination. To our knowledge this is the first case of a neurilemoma located in the tibial nerve reported in the literature.

Antihydrogen production in a combined trap

1993

In this paper we study the properties of a Paul trap with a superimposed magnetic field (combined trap) and discuss the possibility of using this trap to simultaneously store positrons and antiprotons to form antihydrogen.

Rolipram inhibits airway microvascular leakage induced by platelet-activating factor, histamine and bradykinin in guinea-pigs.

1993

Abstract Rolipram (0·1–1000 μg kg−1, i.v.) reduced the increase in microvascular permeability induced by platelet-activating factor (PAF; 50 ng kg−1, i.v.) at different sites of the guinea-pig airways. Rolipram (1–100μg kg−1, i.v.) inhibited histamine (30μg kg−1, i.v.)-and bradykinin (0·3 μg kg, i.v.)-induced airway microvascular leakage. These effects of rolipram were obtained at doses which inhibit histamine (7–20 μg kg−1 min−1)-induced bronchoconstriction (IC50 = 3 ± 1 μg kg, i.v.) without depressing arterial blood pressure in the guinea-pig. Aminophylline (50 mg kg−1) did not change the effect of PAF. The anti-exudative effect of rolipram is of potential therapeutic value in asthma.

Some substrates and inhibitors of cytosolic epoxide hydrolase induce sister-chromatid exchanges in mammalian cells, but do not induce gene mutations …

1993

Abstract Trans -stilbene oxide, trans -β-methylstyrene, 7,8-oxide, trans -β-ethylstyrene, 7,8-oxide, trans -β-propylstyrene 7,8-oxide and 4-fluorochalcone oxide were investigated for genotoxic activity in bacterial and mammalian cells, in the absence of external xenobiotic-metabolising systems. All compounds strongly enhanced the frequency of sister-chromatid exchanges (SCE) in cultured human lymphocytes. None of them was mutagenic in Salmonella typhimurium (reversion of the his − strains TA98, TA100 and TA104). The limit of detection was 1 20,000 to 1 10 6 of the activity of the positive control, benzo[ a ]pyrene 4,5-oxide, depending on the compound and the bacterial strain. Trans -β-methy…

Cellular cation exchange in arterial hypertension: Effects of insulin resistance

1993

Coherent (γ, π0) photoproduction in a local approximation to the delta-hole model

1993

Abstract We develop a local approximation to the Δh model for coherent π 0 photoproduction in nuclei which allows one to perform reliable calculations in heavy nuclei where the traditional Δh approach is technically unfeasible. We evaluate the cross section in different nuclei and compare our results with available data in 12 C.

An in vitro model to study cellular photosensitizer uptake and photodynamic dose-response relationships of tumor cells

1993

Cellular fluorescence intensity (CFI) after incubation with varying concentrations of the photosensitizer Photofrin and the photodynamically induced dose-response relationships of hamster melanoma cells (A-MEL-3) were studied in a recently developed in vitro model. After administration of Photofrin to the extracellular serum-free medium, CFI was evaluated by flow cytometry together with constantly fluorescing latex particles used as a reference. After 5 min, 50% of maximal CFI was found, and after 60 min CFI was maximal. No further increase was obtained during the exposure to Photofrin over the incubation period of 4 h. During this plateau phase, CFI was significantly related to the concent…

Uptake and Metabolism of ?-Carotene Isomers in Rats

1993

Report of a case of localized Castleman's disease with progression to malignant lymphoma.

1993

Microporous hypercrosslinked polystyrene Styrosorb as a restricted access packing in sample clean-up for high performance liquid chromatography. Part…

1993

Styrosorb is a beaded microporous polystyrene with particle sizes between 2 and 4 μm. In spite of hypercrosslinkage the material was seen to swell in organic solvents. The native material is functionalized with Tris-groups at the outer surface of the particles. The average pore diameter was determined as 1.45±0.3 nm from size exclusion data using polystyrene and polyethylene standards in THF. The reversed phase behavior of the restricted access phase Styrosorb was investigated by injection of two test mixtures. Mixture I contained five aromatic amines, mixture II consisted of AmperozideR and four related compounds. The optimum range of mobile phase composition was assessed so that analytes …

Fast, low-level detection of strontium-90 and strontium-89 in environmental samples by collinear resonance ionization spectroscopy

1993

Environmental assessment in the wake of a nuclear accident requires the rapid determination of the radiotoxic isotopes 89Sr and 90Sr. Useful measurements must be able to detect 108 atoms in the presence of about 1018 atoms of the stable, naturally occurring isotopes. This paper describes a new approach to this problem using resonance ionization spectroscopy in collinear geometry, combined with classical mass separation. After collection and chemical separation, the strontium from a sample is surface-ionized and the ions are accelerated to an energy of about 30 keV. Initially, a magnetic mass separator provides an isotopic selectivity of about 106. The ions are then neutralized by charge exc…

ARC A computerized system for urban garbage collection

1993

In this paper we present ARC a computerized system developed for urban garbage collection. The package is intended to help the planners in the design of efficient collection routes and to facilitate the study and evaluation of alternatives concerning issues such as the type and number of vehicles, frequency of collection and type and location of refuse containers. The final product is a “user friendly” system designed to be used by the planners without outside assistance.

Effects of sensitization on vasoactive intestinal polypeptide-induced relaxation and its concentration and binding in guinea-pig airways.

1993

We investigated the relaxant effect of vasoactive intestinal polypeptide (VIP) in trachea and lung parenchyma from normal and sensitized guinea-pigs. A technique by which drug access was restricted to either the mucosal or the adventitial surface of tracheal rings was used. In intact trachea, concentration-response curves for VIP entering from the mucosal surface (pD2 = 6.61 +/- 0.06) were displaced to the right compared with those for adventitial entry (pD2 = 6.78 +/- 0.04). Epithelium removal produced a leftward shift (approximately 2.8-fold) in the mucosal VIP concentration-response curve. Sensitization did not alter the responsiveness (maximal effect) or sensitivity (pD2 values) of trac…

The KeV Majoron as a dark matter particle

1993

We consider a very weakly interacting KeV majoron as dark matter particle (DMP), which provides both the critical density $\rho_{cr} = 1.88 \times 10^{-29} h^{2}$ $g/cm^{3}$ and the galactic scale $M_{gal}$ $\sim m^{3}_{Pl}/m^{2}_{J} \sim 10^{12} M_{\odot} (m_{J}/1 KeV)^{-2}$ for galaxy formation. The majoron couples to leptons only through some new "directly interacting particles", called DIPS, and this provides the required smallness of the coupling constants. If the masses of these DIPS are greater than the scale $V_s$ characterizing the spontaneous violation of the global lepton symmetry they are absent at the corresponding phase transition ($T \sim V_s$) and the majorons are produced d…

Nuclear localization of the protein encoded by the Wilms’ tumor gene WT1 in embryonic and adult tissues

1993

ABSTRACT The human Wilms’ tumor gene WT1 encodes a putative transcription factor implicated in tumorigenesis and in specifying normal urogenital development. We have studied the distribution of WT1 protein and mRNA using immunohistochemistry and in situ hybridization. Monoclonal antibodies were raised against a peptide specific to the first alternative splice site of WT1. Two antibodies specifically reacted on Western blot to this WT1 isoform. Immunofluorescence localized WT1 protein to podocytes during mesonephric and metanephric development. In situ hybridization revealed a similar pattern of expression except that WT1 mRNA was also present in metanephric blastema and renal vesicles. Mess…

On-line trace enrichment for the determination of ethacrynic acid in urine by liquid chromatography and column-switching

1993

Abstract A chromatographic method based on liquid chromatography (LC) using column-switching for the determination of ethacrynic acid in urine samples, is described. The proposed system uses a Hypersil ODS-C18, 30 μm (20 mm × 2.1 mm i.d.) pre-column for the pre-concentration and separation of ethacrynic acid from the biological matrix. Polar urinary compounds are removed by flushing the pre-column with purified water, and the enriched analyte is then switched in back-flush mode onto an HP-LiChrospher RP C18, 5 μm (125 × 4 mm i.d.) analytical column, where it is chromatographed using an acetonitrile-acetate buffer gradient elution. The UV detector was set at 275 nm. The recovery of drug was …

Molecular association of cryptand 221D in NaCl-water solutions. A small-angle neutron scattering study

1993

Molecules of 5-Decyl-4,7,13,16,21-pentaoxa-1,10-diaza-bicyclo-[8.8.5.]tricosan (221D) and its sodium complex, with both a hydrophobic and a hydrophilic portion, are expected to form aggregates in water solutions. This was confirmed by surface tension measurements. The aggregation behaviour was studied by small-angle neutron scattering at two different [NaCl]/[221D] molar ratios, such as to obtain, in one case, aggregates entirely made up of ionic monomers, and in the other, mixed micelles constituted by both ionic and non-ionic units. The variation of the aggregation number and number of aggregates indicated that, in the former case, smaller micelles were formed, as a consequence of repulsi…

Oxygenated germacranes from Santolina chamaecyparissus

1993

The polar fraction of an extract of Santolina chamaecyparissus ssp. squarrosa yielded six new germacrane derivatives and a novel seco-germacrane lactone. The structures have been derived from spectral data, X-ray diffraction and chemical correlations.

Kinetics of Photofrin II in perifocal brain edema.

1993

Photodynamic therapy is under intense investigation as a possible adjuvant for the treatment of malignant tumors of the central nervous system. It relies on the fact that photosensitizers are selectively taken up or retained by malignant tissue. However, most brain tumors are accompanied by substantial vasogenic edema as a consequence of blood-brain barrier disruption within the tumor, leading to extravasation and propagation of plasma constituents into the surrounding brain tissue. Systemically administered photosensitizers may enter healthy tissue together with the edema fluid, possibly leading to sensitization of tissues outside the tumor. To test this hypothesis, vasogenic edema was ind…

Lifetimes of yrast states in 110Cd

1993

Abstract Lifetimes or lifetime limits of 20 yrast levels in 110 Cd have been measured using the recoil-distance method and the NORDBALL array of Compton-suppressed Ge detectors. From the reduced transition probabilities competing rotational and vibrational behaviour of 110 Cd is revealed. Also non-collective states, associated with proton configurations, have been observed.

Influence of data treatment on the shape of 2H NMR T1 curves

1993

A new interpretation of 2H T1 data of glass-forming systems in the range of the range of the caloric glass transition temperature has been proposed. It is shown that with the traditional treatment of the data the timescale of structural relaxation has an influence on the observed spin-lattice relaxation times. Avoiding this problem with a different treatment of the experimental data, it is possible to compare the 2H T1 data directly with corresponding 1H data.