In their natural environment, organisms receive information through multiple sensory channels and these inputs from different sensory systems are routinely combined into integrated percepts. ...Previously, we reported that in a population of schizophrenics, deficits in audiovisual integration were observed for complex stimuli (auditory and visual syllables), but not for more simple ones (beeps and light flashes). Here, we investigated multisensory integration of emotional information in a group of schizophrenic patients. In Experiment 1, we found a reduced effect of an emotional voice on the categorization of a facial expression. In Experiment 2, the reverse test situation was presented, and, here, we observed an exaggerated effect of a face expression on the categorization of an emotional voice. Results are discussed in the light of current models of multisensory integration and their relevance for schizophrenia.
Hydrogels, physically crosslinked through stereocomplex formation, were obtained by mixing aqueous solutions of dextran with
l-lactic acid grafts and dextran with
d-lactic acid grafts. Protein-loaded ...hydrogels were simply prepared by dissolving the protein in these dextran solutions prior to mixing. It was shown that under physiological conditions the gels are fully degradable. When the gels were exposed to an aqueous buffer solution, they first showed a swelling phase in which their weight increased 2–3 times due to absorption of water, followed by a dissolution phase. The degradation time depended on the composition of the hydrogel, i.e., the number of lactate grafts, the length and polydispersity of the grafts and the initial water content, and varied from 1 to 7 days. Most likely, the degradation of the stereocomplex hydrogel started with hydrolysis of the carbonate ester, which links the lactate graft to dextran. The gels showed a release of the entrapped model proteins (IgG and lysozyme) over 6 days and the kinetics depended on the gel characteristics, such as the polydispersity of the lactate grafts and the initial water content. Lysozyme was mainly released by Fickian diffusion, indicating that its hydrodynamic diameter is smaller than the hydrogel mesh size. On the other hand the release of IgG was governed by diffusion as well as swelling/degradation of the hydrogel. Importantly, the proteins were quantitatively released from the gels and with full preservation of the enzymatic activity of lysozyme, emphasizing the protein-friendly preparation method of the protein-loaded stereocomplex hydrogel.
Hydrogels are based on hydrophilic polymers, which are crosslinked to prevent dissolution in water. Because hydrogels can contain large amounts of water, they are interesting devices for the delivery ...of proteins. In this contribution a biodegradable dextran hydrogel is described which is based on physical interactions and is particularly suitable for the controlled delivery of pharmaceutically active proteins. The unique feature of our system is that the preparation of the hydrogels takes place in an all-aqueous solution, by which the use of organic solvents is avoided. Furthermore, chemical crosslinking agents are not needed to create the hydrogels, since crosslinking is established physically by stereocomplex formation between enantiomeric oligomeric lactic acid chains. The hydrogel is simply obtained after mixing aqueous solutions of dextran(
l)-lactate and dextran(
d)-lactate. In this contribution, the formation of the hydrogels as well as their protein release properties and degradation behavior are discussed.
This paper describes a novel hydrogel concept, which is based on self-assembling of enantiomeric lactic acid oligomers (stereocomplex formation) grafted to dextran. The hydrogels are prepared in an ...all-aqueous environment. For this purpose, l- and d-lactic acid oligomers were coupled to dextran, yielding dex−(l)lactate and dex−(d)lactate, respectively. Upon dissolving each product in water separately and mixing the solutions, we observed that a hydrogel is formed at room temperature as demonstrated by rheological measurements. The storage modulus of the obtained hydrogel strongly decreased upon heating to 80 °C, while it was restored upon cooling to 20 °C, demonstrating the thermoreversibility and the physical nature of the cross-links. Rheological experiments with monodisperse lactic acid oligomers grafted to dextran showed that the degree of polymerization (DP) of the lactic acid oligomers must be at least 11 to obtain a hydrogel. The hydrogel characteristics can be modulated by varying the degree of polymerization (DP, number of lactate units per oligomer) and the degree of substitution (DS, number of lactic acid side chains per 100 glucopyranose units) of the dex−lactate products, as well as the water content of the dex−lactate solutions. Stronger gels were obtained by increasing the DP and DS and by decreasing the water content. FTIR−photoacoustic (PA) analysis demonstrated that in the hydrogels stereocomplexes were formed between the lactic acid oligomers of opposite chirality.
A novel hydrogel system in which crosslinking is established by stereocomplex formation between lactic acid oligomers of opposite chirality is proposed. To investigate the feasibility of this novel ...system, we first investigate whether there is an operation window where lactic acid oligomers in either the
d- or
l-form do not give a crystalline phase, whereas in a blend of the
d- and
l-form stereocomplex formation occurs. Therefore,
d- and
l-lactic acid oligomers with different degrees of polymerization (DP) were prepared and analyzed using DSC. It was shown that crystallinity was present in
d- or
l-oligomers with DP ≥11. On the other hand, in blends of
d- and
l-oligomers of lactic acid crystallinity (stereocomplexation) was already observed at a DP ≥7. In the next step,
l- and
d-lactic acid oligomers were coupled via their terminal hydroxyl group to dextran, yielding dex-(
l)lactate and dex-(
d)lactate, respectively. Upon dissolving each product in water separately and mixing the solutions, a hydrogel is formed at room temperature as demonstrated by rheological measurements. The storage modulus of the obtained hydrogel strongly decreased upon heating to 80°C, while it was restored upon cooling to 20°C demonstrating the thermo-reversibility and the physical nature of the cross-links. The storage modulus of the gels depends on the degree of polymerization of the lactate acid grafts and their degree of substitution on dextran. Interestingly, gel formation was favored when one lactic oligomer was coupled via its hydroxyl group whereas the oligomer of opposite chirality was coupled via its carboxylic acid group. This is ascribed to the parallel packing of the oligomers in stereocomplexes.
d- and l-lactic acid oligomers were synthesized by polymerization of d- or l-lactide using 2-(2-methoxyethoxy)ethanol (MEE) and stannous octoate as initiator and catalyst, respectively. The average ...degree of polymerization (DPav) of the oligomers could be tailored by the monomer/initiator ratio. HPLC and GPC analysis showed that the oligomers had a M w/M n ratio of around 1.5. Mass spectroscopic analysis revealed that products contained besides MEE−(lactate) n =2,4,6,etc. also MEE−(lactate) n =1,3,5,etc.. The latter products are most likely formed due to transesterification reactions. Monodisperse lactic acid oligomers (DP 1−16) were obtained from the polydisperse oligomers by preparative HPLC and characterized by NMR and mass spectrometry. DSC analysis showed that crystallinity was present in d- or l-oligomers with DP ≥ 11. On the other hand, in blends of d- and l-oligomers of lactic acid crystallinity (stereocomplexation) was observed at a DP ≥ 7.
Primate Origins Ravosa, Matthew J; Dagosto, Marian
2007
eBook
This book provides a novel focus on adaptive explanations for cranial and postcranial features and functional complexes, socioecological systems, life history patterns, etc. in early primates. It ...further offers a detailed rendering of the phylogenetic affinities of such basal taxa to later primate clades as well as to other early/recent mammalian orders. In addition to the strictly paleontological or systemic questions regarding Primate Origins, the editors concentrate on the adaptive significance of primate characteristics. Thus, the book provides the broadest possible perspective on early primate phylogeny and the adaptive uniqueness of the Order Primates.
The extended OPAL silicon strip microvertex detector Anderson, S.; Batley, J.R.; Beck, G.A. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
02/1998, Letnik:
403, Številka:
2
Journal Article
Recenzirano
Odprti dostop
The OPAL experiment at the CERN LEP collider recently increased the geometrical acceptance of its silicon microvertex detector. The azimuthal coverage is improved by adding one pair of detector ...modules to each of the two layers, while the polar angle coverage is extended by adding new detector modules in line with the existing ones. This improves the efficiency for high quality tracking in OPAL and in particular for b quark tagging in Higgs boson searches. A description of the detector is given, with emphasis on new or modified elements with respect to the earlier version. Results on the performance of the new detector are presented.
The radiation monitoring and beam dump system of the OPAL silicon microvertex detector is described. This system was designed and implemented to measure the radiation dose over time scales varying ...from a millisecond to a year, and to induce a fast beam dump if the radiation exceeds a given threshold in dose and in dose rate within a very small time interval. The system uses reverse-biased silicon diodes as sensitive elements and good stability is achieved by AC coupling of the amplifiers to the sensors.
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