Search

This study addresses the dynamics of the Agulhas inshore front in the submesoscale range upstream of 26° E. Submesoscale frontal eddies are observed in the vicinity of Port Elizabeth (26° E) from satellite images and in observations collected from underwater gliders. Using a submesoscale‐resolving numerical model (dx ∼ 0.75 km), we are able to simulate similar submesoscale eddies. Barotropic instability is confirmed as the generation mechanism by a one‐dimensional linear stability analysis and an eddy kinetic energy budget. Kinetic energy is transferred from the mean flow to the eddies through the mean horizontal shear, which is a signature of barotropic instability. When the Agulhas Current is in a nonmeandering state, submesoscale eddy generation is a recurrent process which locally drives the front's variability. Along the front, the spatial variability of barotropic instability is shaped by the background strain. A large strain aligned with the frontal axis intensifies the frontal shear upstream of 28° E while a weakening of the strain allows for barotropic instability to be triggered downstream. Although an intermittent process, the barotropic instability shows a dominant period of variability comparable with the variability of the Agulhas Current and Undercurrent. Submesoscale frontal eddies are generated due to barotropic instability in the Agulhas CurrentThe background strain provides favorable conditions for instability generationA new regime of variability is highlighted in addition to the two modes described by Paldor and Lutjeharms (2009)

Polyzyklische aromatische Kohlenwasserstoffe (PAK) enthaltende Teeröle (Kreosote), wie sie u. a. zur Imprägnierung von Bahnschwellen eingesetzt wurden, stellen ebenso wie kontaminierte Böden ehemaliger Industriegelände hohe Anforderungen an eine fachgerechte Entsorgung. Pyrolyseprodukte aus organischem Material, die besonders hohe Anteile an krebserzeugenden PAK enthalten wie Braun- und Steinkohlenteeröle sind von der MAK-Kommission in Kategorie 1 eingestuft. Für die Gefährdungsbeurteilung bei Tätigkeiten mit diesen PAK-Gemischen ist als Bezugssubstanz bei Arbeitsplatzmessungen der Stoff Benzo[a]pyren zu wählen. Für die Bewertung der inhalativen Belastung gemäß der Technischen Regel für Gefahrstoffe (TRGS) 910 gelten hierfür eine Akzeptanz- und Toleranzkonzentration von 70 bzw. 700 ng/m3. Der dermalen Aufnahme von PAK kommt jedoch eine maßgebliche Rolle zu. Als Ziel war zu klären, ob die Akzeptanzkonzentration eingehalten werden kann. Begleitet von aufeinanderfolgenden Arbeitsschutzmaßnahmen, wurden in zwei Bahnschwellenbetrieben und einer Anlage zur thermischen Bodensanierung mehrfach Arbeitsplatzmessungen und ein Biomonitoring anhand des Markers 1‑Hydroxypyren (1-OHP) durchgeführt. Bei den Arbeitsplatzmessungen zeigten sich sowohl Überschreitungen der Akzeptanz- als auch der Toleranzkonzentration bei kritischen Tätigkeiten bis zum Dreifachen. Beim Biomonitoring zeigte sich keine Korrelation zu den Messungen in der Arbeitsplatzluft. Es erwies sich jedoch als geeignet, den Erfolg der getroffenen Maßnahmen zu überprüfen. In Einzelfällen zeigten sich sehr hohe 1‑OHP-Konzentrationen bis zu 350 µg/g Kreatinin. Überwiegend wurden jedoch am Ende der Studie Werte im Bereich des Biologischen Arbeitsstoff-Referenzwertes (BAR) gemessen. Eine erfolgreiche Umsetzung des Risikokonzeptes erscheint somit möglich. Railway sleepers impregnated with tar oils (creosote) containing polycyclic aromatic hydrocarbons (PAH) and contaminated soil from industrial wasteland require professional waste management. The maximum workplace concentration (MAK) committee has classified pyrolysis products from organic materials, such as tar oils from lignite and anthracite coal as carcinogens according to category 1. Benzo[a]pyrene (BaP) is used as the reference substance for exposure assessment when working with materials containing PAH. Acceptable and tolerable concentrations of 70 ng/m3and 700 ng/m3, respectively, are used for the assessment of inhalative exposure according to the technical rule for hazardous substances (TRGS) 910. Dermal uptake of PAH is of particularly high relevance. The aim of this study was to check if the acceptable concentrations can be complied with. Accompanied by consecutive occupational protective measures, air monitoring and biological biomonitoring using 1‑hydroxypyrene (1-OHP) as internal marker were performed in two railway sleeper recycling companies and a thermal soil remediation company. Workplace measurements showed results exceeding the acceptable and the tolerable concentrations by up to three times for critical tasks. The results of biological monitoring did not correlate with those of air monitoring; however, biological monitoring enabled the efficiency of applied protective measures to be checked. In some cases concentrations of 1‑OHP up to 350 µg/g creatinine were found. At the end of this study most of the results were in the range of the German BAR value (the biological reference value for workplace substances). A successful implementation of the risk-related concept according to TRGS 910 therefore seems to be possible.

Cruise data sets, satellite remote sensing observations, and model data analyses are combined to highlight the existence of a coastal surface poleward flow in the southwest of Madagascar: the Southwest MAdagascar Coastal Current (SMACC). The SMACC is a relatively shallow (<300 m) and narrow (<100 km wide) warm and salty coastal surface current, which flows along the south western coast of Madagascar toward the south, opposite to the dominant winds. The warm water surface signature of the SMACC extends from 22°S (upstream) to 26.4°S (downstream). The SMACC exhibits a seasonal variability: more intense in summer and reduced in winter. The average volume transport of its core is about 1.3 Sv with a mean summer maximum of 2.1 Sv. It is forced by a strong cyclonic wind stress curl associated with the bending of the trade winds along the southern tip of Madagascar. The SMACC directly influences the coastal upwelling regions south of Madagascar. Its existence is likely to influence local fisheries and larval transport patterns, as well as the connectivity with the Agulhas Current, affecting the returning branch of the global overturning circulation. A new coastal current: the Southwest MAdagascar Coastal Current (SMACC) has been uncovered. This coastal current flows along the southwestern coast of Madagascar toward the south. The SMACC is a relatively shallow (<300 m) and narrow (<100 km wide) warm and salty surface current, which is more intense in summer and reduced in winter. The Southwest MAdagascar Coastal Current has a downstream impact on the upwelling system at the south of Madagascar which is a physical process inducing local fertilization. As such, the Southwest MAdagascar Coastal Current has key implications for studies about the greater Agulhas Current system, remote connections between oceanographic systems, biophysical coupling in upwelling systems, fisheries management, local livelihoods, and so forth. The uncovering of the SMACC has significant implications for the improved broader understanding of ocean systems around the world. The Southwest MAdagascar Coastal Current (SMACC) is a newly discovered surface poleward currentThe SMACC exhibits a seasonal cycle and is driven by the wind stress curlThe SMACC influences the coastal upwelling region south of Madagascar

Gliders were deployed for the first time in the Agulhas Current region to investigate processes of interactions between western boundary currents and shelf waters. Continuous observations from the gliders in water depths of 100–1000 m and over a period of 1 month provide the first high‐resolution observations of the Agulhas Current's inshore front. The observations collected in a nonmeandering Agulhas Current show the presence of submesoscale cyclonic eddies, generated at the inshore boundary of the Agulhas Current. The submesoscale cyclones are often associated with warm water plumes, which extend from their western edge and exhibit strong northeastward currents. These features are a result of shear instabilities and extract their energy from the mean Agulhas Current jet. Glider observations show the presence of submesoscale cyclonic eddies at the inshore boundary of the Agulhas CurrentSubmesoscale cyclones are generated through shear instability of the currentSubmesoscale cyclones drive warm water plumes towards the continental shelf

Décrire la mise en place et rapporter les premiers résultats d’un dépistage de la rétinopathie diabétique (RD) par technique d’électro-rétinographie (ERG) réalisée par une infirmière de pratique avancée (IPA).

Hybrid materials consisting of stimuli-responsive polymers (SRPs) in an inorganic matrix have the potential for use in a variety of applications as switchable or tunable membranes, coatings, adsorbents, and solute reservoirs. Poly(N-isopropylacrylamide) (PNIPAAM) is an SRP that exhibits inverse solubility behavior in water upon an increase in temperature through a transition from a hydrophilic to a hydrophobic state. In an earlier communication, we demonstrated that when PNIPAAM is encapsulated in a silica matrix by a sol−gel process, the resultant hybrid material can function as a switchable molecular filter. In this paper, we present detailed investigation and characterization of these membranes, which exhibit reversible on/off permeation behavior, above and below the transition temperature of PNIPAAM, respectively. Scanning and transmission electron microscopic studies show that the membranes are highly homogeneous, and phase separation of the polymers is not observed. Differential scanning calorimetry, contact angle, and permeation experiments indicate that the PNIPAAM in the hybrid materials retains its aqueous critical solubility transition. Nitrogen porosimetry measurements indicated that the dried hybrid materials are mesoporous with an average pore size of ~30 Å. Permeation of solutions of poly(ethylene glycols) (PEGs) varying in molecular weight through the hybrid membranes clearly demonstrates that they can function as switchable molecular filters. Under controlled pressure, the membranes are impermeable to water below the transition temperature. At the same pressures, above the transition temperature, membranes are permeable to PEGs with molecular weights below a threshold value. In the membranes studied, the molecular weight of PNIPAAM encapsulated in the silica did not dramatically affect the PEG molecular weight threshold for permeation.

Neurocan is a component of the extracellular matrix in brain. Due to its inhibition of neuronal adhesion and outgrowth in vitro and its expression pattern in vivo it was suggested to play an important role in axon guidance and neurite growth. To study the role of neurocan in brain development we generated neurocan-deficient mice by targeted disruption of the neurocan gene. These mice are viable and fertile and have no obvious deficits in reproduction and general performance. Brain anatomy, morphology, and ultrastructure are similar to those of wild-type mice. Perineuronal nets surrounding neurons appear largely normal. Mild deficits in synaptic plasticity may exist, as maintenance of late-phase hippocampal long-term potentiation is reduced. These data indicate that neurocan has either a redundant or a more subtle function in the development of the brain.

Using the computer system PASS (prediction of activity spectra for substances), which predicts simultaneously several hundreds of biological activities, a training set for discriminating between drugs and nondrugs is created. For the training set, two subsets of databases of drugs and nondrugs (a subset of the World Drug Index, WDI, vs the Available Chemicals Directory, ACD) are used. The high value of prediction accuracy shows that the chemical descriptors and algorithms used in PASS provide highly robust structure−activity relationships and reliable predictions. Compared to other methods applied in this field, the direct benchmark undertaken with this paper showed that the results obtained with PASS are in good accordance with these approaches. In addition, it has been shown that the more specific drug information used in the training set of PASS, the more specific discrimination between drug and nondrug can be obtained.

In previous studies L-fucose has been shown to facilitate long-term memory formation and to enhance and prolong long-term potentiation (LTP). To search for possible presynaptic or postsynaptic mechanisms that are affected by L-fucose, we examined the effect of L-fucose on (1) inhibition of LTP induction via glutamate receptors by antagonists, (2) paired-pulse facilitation, and (3) presynaptic transmitter release. Coapplication of 0.2 mM L-fucose with the competitive N-methyl-D-aspartate (NMDA) receptor antagonist, D-2-amino-5-phosphonovalerate (AP5), or coapplication of 0.2 mM L-fucose in the presence of an inhibitor for class I/II metabotropic glutamate receptors, (S)-alpha-methyl-4-carboxyphenylglycine (MCPG), reversed LTP blockade in the CA1-region of hippocampal slices. In contrast, L-fucose had no effect on the LTP blockade by the noncompetitive NMDA ion-channel blocker (5R,10S)-(+)-5-Methyl-10, 11-dihydro-5H-dibenzo[a,d]cyclohepten-5, 10-imine hydrogen maleate (MK-801). Paired-pulse facilitation, which is a primarily presynaptic phenomenon of short-term plasticity, was decreased in the presence of 0.2 mM L-fucose. Furthermore, L-fucose enhanced the K(+)-stimulated release of [(3)H]-D-aspartate from preloaded hippocampal slices in a concentration-dependent manner. These observations demonstrate an influence of L-fucose on transmitter release that in turn can increase transmitter availability at postsynaptic glutamate receptors. This effect of L-fucose may contribute to the LTP facilitation seen in vitro and in vivo as well as to improvement in memory formation.

The origin of ultralow‐velocity zones (ULVZs) remains an open question despite recent advances in mineral physics and seismology. Here, we examine the hypothesis that FeSi formed from core‐mantle chemical reactions is a plausible source of ULVZs at the core‐mantle boundary (CMB). The sound velocities of B2‐structured FeSi were measured up to 115(2) GPa and 1600(200) K by nuclear inelastic scattering (NIS) in laser‐heated diamond anvil cells (LH‐DACs). Within uncertainties, the sound velocities of B2‐FeSi display negligible anharmonicity, hence validating the extrapolation of velocity‐density relations (Birch's law) to P‐Tconditions of the CMB. The sound velocities of B2‐FeSi are significantly lower compared to other candidate phases in a lowermost mantle assemblage, and the Preliminary Reference Earth Model at CMB conditions. Less than 8.4 vol% of FeSi in the aggregate is thus sufficient to explain both the velocity decrements and the high density anomaly observed in a wide range of ULVZs. Seismic studies have revealed patches on the Earth's core‐mantle boundary (CMB), which have extremely low seismic velocities. However, the origin of these so‐called ultralow‐velocity zones (ULVZs) remains unclear. One plausible source could be FeSi, which is assumed to form from chemical reactions between material from the core and the mantle. Here, we test this hypothesis in an experimental study, where the elastic behavior of FeSi is measured while the sample is exposed to very high pressures and temperatures comparable to those in the Earth's lower mantle. From these measurements we derived the sound velocities of the high‐pressure phase of FeSi at the CMB. We found that the sound velocities of FeSi are significantly lower than those of the average lowermost mantle measured in seismic studies, and also lower than those of other mineral phases in this region, which are also considered as potential sources of ULVZs. FeSi is thus a plausible candidate to explain the origin of ULVZs. Our results show that less than 8.4% of FeSi by volume in the aggregate are enough to explain both the amplitude of the velocity reduction and the high density anomaly observed in a wide range of ULVZs. Very low sound velocities in B2‐FeSi, a candidate phase at the CMB, measured up to 115 GPa and 1600 K by NISNegligible anharmonic contributions to sound velocities validate the extrapolation of Birch's law to CMB conditionsLess than 8.4 vol% B2‐FeSi produced by core‐mantle reactions are enough to explain the seismic anomalies associated with the ULVZs Very low sound velocities in B2‐FeSi, a candidate phase at the CMB, measured up to 115 GPa and 1600 K by NIS Negligible anharmonic contributions to sound velocities validate the extrapolation of Birch's law to CMB conditions Less than 8.4 vol% B2‐FeSi produced by core‐mantle reactions are enough to explain the seismic anomalies associated with the ULVZs

Abstract. Kindling is a generally accepted model for studying epilepsy development in the context of overexpression of processes of neuronal plasticity. In previous studies we have shown that establishment of kindling by repeated application of subconvulsive doses of pentylenetetrazol (PTZ) also led to marked changes in hippocampal excitability and an impairment in learning behaviour. With the intention of further investigating the relationship between kindling development, kindling-induced changes in excitability and learning deficits, rats were chemically kindled under pretreatment with the nootropic drug piracetam. Furthermore, we tested acute piracetam effects on developed kindling seizures, the learning deficit and potentiation effects. At the investigated dose piracetam did not influence the kindling development. The kindling-induced potentiation of hippocampal field potentials was significantly diminished in piracetam-pretreated rats. Piracetam acutely injected completely antagonized this potentiation effect. Piracetam brought about a significant improvement in impaired learning performance in rats pretreated during kindling induction and acutely injected before the learning experiment, respectively. Possible correlations between the suppressing of the kindling related potentiation in hippocampal structures by piracetam and its beneficial effect on learning impairment are discussed as antagonizing overexpression of potentiation in the course of kindling.

1. Hippocampal long‐term potentiation (LTP) may serve as an elementary process underlying certain forms of learning and memory in vertebrates. As is the case with behavioural memory, hippocampal LTP in the rat CA1 region and in the dentate gyrus occurs in stages, which can be separated by an inhibitor of RNA synthesis. 2. Experiments have been performed in two brain regions, in the hippocampal CA1 region in vitro and in the dentate gyrus in vivo. 3. Maintenance of hippocampal LTP in the CA1 region in vitro was influenced by the RNA synthesis inhibitor actinomycin D from 4 h onwards. 4. The effect of actinomycin D on the time course of the population spike potentiation was more pronounced than the effect on the time course of the EPSP component, suggesting different mechanisms for the two forms of potentiation. 5. Intrahippocampal and intracerebroventricular injection of actinomycin D into rats prevented a late stage of LTP in the dentate gyrus in vivo measured as the population spike amplitude. 6. Since actinomycin D was only effective in influencing the maintenance of LTP when applied before tetanization, the requirement for transcription during LTP may have a critical time window. 7. Actinomycin D influenced the maintenance of LTP specifically, since the drug did not alter any potentials in control experiments after its removal or when it was administered shortly after tetanization. A second, structurally different RNA synthesis inhibitor, 5,6‐dichloro‐1‐beta‐D‐ribofuranosyl benzimidazole, mimicked the effect of actinomycin D in vitro.

Large real-time applications often impose stringent requirements on the system architecture concerning the number of different operating conditions under which they must operate. Modes and mode changes are a powerful concept to represent these operational phases within the system architecture.

In male young adult Wistar rats the influences of nucleus raphe electrocoagulation, spinal cord dissection (cordotomy between C7 and Th1), vagotomy and denervation of liver hilus by phenol on liver cytochrome P450-system (cytochrome P450 concentration, ethylmorphine N-demethylation and ethoxycoumarin O-deethylation activities, hexobarbitone sleeping time) were investigated.

Trans-synaptic activation of gene expression is linked to long-term plastic adaptations in the nervous system. To examine the molecular program induced by synaptic activity, we have employed molecular cloning techniques to identify an immediate early gene that is rapidly induced in the brain. We here report the entire nucleotide sequence of the cDNA, which encodes an open reading frame of 396 amino acids. Within the hippocampus, constitutive expression was low. Basal levels of expression in the cortex were high but can be markedly reduced by blockade of N-methyl-D-aspartate receptors. By contrast, synaptic activity induced by convulsive seizures increased mRNA levels in neurons of the cortex and hippocampus. High-frequency stimulation of the perforant path resulted in long-term potentiation and a spatially confined dramatic increase in the level of mRNA in the granule cells of the ipsilateral dentate gyrus. Transcripts were localized to the soma and to the dendrites of the granule cells. The dendritic localization of the transcripts offers the potential for local synthesis of the protein at activated postsynaptic sites and may underlie synapse-specific modifications during long-term plastic events.

Prothymosin α and thymosin α1are believed to be thymus-derived, hormone-like materials with immunomodulatory functions performed outside the cell. These functions are inconsistent with the existence of a full length cDNA clone that does not encode an amino-terminal signal peptide or several consecutive hydrophobic residues. A study of the prothymosin α mRNAs and genes was undertaken in search of evidence for secreted forms of the protein. Prothymosin α mRNA was localized exclusively on free, rather than membrane-bound, polysomes. Upon screening cosmid and plasmid libraries totaling 2 × 106clones, a gene family consisting of six members was identified. Sequence information from the 5′-ends of all the genes indicated that none encodes an amino-terminal signal peptide. One of the genes, apparently by means of alternate splicing, gives rise to two prothymosin α mRNAs, one of which has an additional internal glutamic acid codon with respect to the other. Comparison of the translated nucleic acid sequences of the five remaining genes with those encoded in the mRNAs revealed 30–98% homology in the first 50 amino acids. These five genes appear to be processed genes and/or pseudogenes. The localization of prothymosin α mRNAs on free polysomes, together with the partial nucleotide sequences of the genes, strongly suggest an intracellular function for prothymosin α. Therefore, the possibility must be raised that prothymosin α and its peptide derivatives act as xenobiotics when introduced into assays of immune function.

Not Available

A series of test substrates have been synthesized to establish the effect of termini on the putative exoribonuclease H activity of reverse transcriptase. Recombinant reverse transcriptase from human immunodeficiency virus, natural enzyme from avian myeloblastosis virus, and a known endonuclease, Escherichia coli ribonuclease H, cleaved relaxed, circular, covalently closed plasmids in which 770 consecutive residues of one strand were ribonucleotides. The avian enzyme also deadenylated capped globin mRNA with a covalently attached oligo(dT) tail at the 3' end. These results resolve a long-standing controversy--that the viral enzymes are obligatory exonucleases in vitro, based on their failure to cleave certain substrates for E. coli ribonuclease H, including circular poly(A).linear poly(T) and ribonucleotide-substituted supercoiled plasmids, but resemble endonucleases in vivo, based on their ability to degrade RNA in complex DNA.RNA hybrids. The data strongly suggest that the viral enzymes are endonucleases with exquisite sensitivity to the conformation of heteroduplexes. Inhibition of viral, but not cellular, ribonuclease H with ribonucleoside-vanadyl complexes further distinguishes these enzymes.

In order to obtain further evidence of the pharmacological effects of retention-facilitating substances, the influence of sodium-orotate, methylglucamine orotate, and pirazetam on the bioelectrical activity of central nervous system structures were studied. Sodium orotate showed no influence on the cortical and hippocampal spontaneous EEGs of conscious nonimmobilized rabbits. The amplitude of the first surface-positive wave of the cortical evoked potential that was elicited by stimulation of tooth pulp was, however, significantly increased in long-lasting terms by both pirazetam and the two salts of orotic acid. Similarly, the three substances also influenced the changes in excitability induced by PTP of tooth pulp. The findings suggest that these chemicals facilitate in nonspecific manner responses to externally applied stimuli through central structures. The relationships between the altered stimulus response and the retention-facilitating action of these substances are discussed.

Abstract: Photodynamic therapy (PDT) of tumours in hollow organs requires light application devices which enable homogeneous illumination of the tissue surface in hollow organs. This paper presents two laser light application systems generating a homogeneous light distribution and one monitoring unit which detects variations in the applied laser light intensity during treatment. A cylindrical light diffuser has been developed for PDT of cylindrical organs (e.g. bronchus, oesophagus). This system guarantees a defined homogeneity of the laser light intensity. An exact positioning to a defined treatment area is possible. Adjacent tissue is prevented from laser light irradiation. A special lens system has been developed for the irradiation of flat surfaces (e.g. skin, carina, organ wall of the large bowel and the stomach). The illumination area is defined by the distance to the tissue and the large aperture. The size of the system allows for it to pass through the biopsy channel of conventional endoscopes. A monitoring device recently developed helps to detects of the fibre, changes in the medium around the fibre tip, and variations of the laser output power during laser treatment. All devices serve for evaluating an accurate light dosimetry in clinical PDT.