The fundamental plane of clusters of galaxies: a quest for understanding cluster dynamics and morphology

We discuss implications of the fundamental plane parameters of clusters of galaxies derived from combined optical and X-ray data of a sample of 78 nearby clusters. In particular, we investigate the dependence of these parameters on the dynamical state of the cluster. We introduce a new concept of allocation of the fundamental plane of clusters derived from their intrinsic morphological properties, and put some theoretical implications of the existence of a fundamental plane into perspective.We discuss implications of the fundamental plane parameters of clusters of galaxies derived from combined optical and X-ray data of a sample of 78 nearby clusters. In particular, we investigate the dependence of these parameters on the dynamical state of the cluster. We introduce a new concept of allocation of the fundamental plane of clusters derived from their intrinsic morphological properties, and put some theoretical implications of the existence of a fundamental plane into perspective

Interactive Videos vs. Hypertext Documents – The Effect on Learning Quality and Time Effort when Acquiring Procedural Knowledge

The use of information systems and the rise of new learning concepts have changed the way individuals are acquiring knowledge in organizational, educational and private contexts. Recently, video tutorials have become a widely-used instrument for learning and successful platforms emerged, offering massive open online courses based on video content. With the existence of different learning technologies the question arises: How these media formats affect the learning performance of individuals? We introduce interactive videos as a new media format and compare this technology to hypertext documents in an educational context. Our results from an experiment with 130 participants reveal that the learning quality can be significantly increased when interactive videos are used to acquire procedural knowledge. However, we did not observe any effect on time effort

Optical absorption of non-interacting tight-binding electrons in a Peierls-distorted chain at half band-filling

In this first of three articles on the optical absorption of electrons in half-filled Peierls-distorted chains we present analytical results for non-interacting tight-binding electrons. We carefully derive explicit expressions for the current operator, the dipole transition matrix elements, and the optical absorption for electrons with a cosine dispersion relation of band width $W$ and dimerization parameter $\delta$. New correction (``$\eta$''-)terms to the current operator are identified. A broad band-to-band transition is found in the frequency range $W\delta < \omega < W$ whose shape is determined by the joint density of states for the upper and lower Peierls subbands and the strong momentum dependence of the transition matrix elements.Comment: 17 pages REVTEX 3.0, 2 postscript figures; hardcopy versions before May 96 are obsolete; accepted for publication in The Philosophical Magazine

A new model for preclinical testing of dermal substitutes for human skin reconstruction

Background: Currently, acellular dermal substitutes used for skin reconstruction are usually covered with split-thickness skin grafts. The goal of this study was to develop an animal model in which such dermal substitutes can be tested under standardized conditions using a bioengineered dermo-epidermal skin graft for coverage. Methods: Bioengineered grafts consisting of collagen type I hydrogels with incorporated human fibroblasts and human keratinocytes seeded on these gels were produced. Two different dermal substitutes, namely Matriderm®, and an acellular collagen type I hydrogel, were applied onto full-thickness skin wounds created on the back of immuno-incompetent rats. As control, no dermal substitute was used. As coverage for the dermal substitutes either the bioengineered grafts were used, or, as controls, human split-thickness skin or neonatal rat epidermis were used. Grafts were excised 21days post-transplantation. Histology and immunofluorescence was performed to investigate survival, epidermis formation, and vascularization of the grafts. Results: The bioengineered grafts survived on all tested dermal substitutes. Epidermis formation and vascularization were comparable to the controls. Conclusion: We could successfully use human bioengineered grafts to test different dermal substitutes. This novel model can be used to investigate newly designed dermal substitutes in detail and in a standardized wa

Demonstration of safety of intravenous immunoglobulin in geriatric patients in a long-term, placebo-controlled study of Alzheimer's disease.

INTRODUCTION:We present safety results from a study of Gammagard Liquid intravenous immunoglobulin (IGIV) in patients with probable Alzheimer's disease. METHODS:This was a placebo-controlled double-blind study. Subjects were randomized to 400 mg/kg (n = 127), 200 mg/kg (n = 135) IGIV, or to 0.25% human albumin (n = 121) administered every 2 weeks ± 7 days for 18 months. RESULTS:Elevated risk ratios of IGIV versus placebo included chills (3.85) in 9.5% of IGIV-treated subjects (all doses), compared to 2.5% of placebo-treated subjects, and rash (3.08) in 15.3% of IGIV-treated subjects versus 5.0% of subjects treated with placebo. Subjects in the highest IGIV dose group had the lowest proportion of SAEs considered related to product (2 of 127 [1.6%]). Subjects treated with IGIV experienced a lower rate of respiratory and all other infections compared to placebo. DISCUSSION:IGIV-treated subjects did not experience higher rates of renal failure, lung injury, or thrombotic events than the placebo group. There were no unexpected safety findings. IGIV was well tolerated throughout 18 months of treatment in subjects aged 50-89 years

LC-MS/MS-based proteome profiling in Daphnia pulex and Daphnia longicephala: the Daphnia pulex genome database as a key for high throughput proteomics in Daphnia

<p>Abstract</p> <p>Background</p> <p>Daphniids, commonly known as waterfleas, serve as important model systems for ecology, evolution and the environmental sciences. The sequencing and annotation of the <it>Daphnia pulex </it>genome both open future avenues of research on this model organism. As proteomics is not only essential to our understanding of cell function, and is also a powerful validation tool for predicted genes in genome annotation projects, a first proteomic dataset is presented in this article.</p> <p>Results</p> <p>A comprehensive set of 701,274 peptide tandem-mass-spectra, derived from <it>Daphnia pulex</it>, was generated, which lead to the identification of 531 proteins. To measure the impact of the <it>Daphnia pulex </it>filtered models database for mass spectrometry based <it>Daphnia </it>protein identification, this result was compared with results obtained with the Swiss-Prot and the <it>Drosophila melanogaster </it>database. To further validate the utility of the <it>Daphnia pulex </it>database for research on other <it>Daphnia </it>species, additional 407,778 peptide tandem-mass-spectra, obtained from <it>Daphnia longicephala</it>, were generated and evaluated, leading to the identification of 317 proteins.</p> <p>Conclusion</p> <p>Peptides identified in our approach provide the first experimental evidence for the translation of a broad variety of predicted coding regions within the <it>Daphnia </it>genome. Furthermore it could be demonstrated that identification of <it>Daphnia longicephala </it>proteins using the <it>Daphnia pulex </it>protein database is feasible but shows a slightly reduced identification rate. Data provided in this article clearly demonstrates that the <it>Daphnia </it>genome database is the key for mass spectrometry based high throughput proteomics in <it>Daphnia</it>.</p

Human amniotic fluid derived cells can competently substitute dermal fibroblasts in a tissue-engineered dermo-epidermal skin analog

Purpose: Human amniotic fluid comprises cells with high differentiation capacity, thus representing a potential cell source for skin tissue engineering. In this experimental study, we investigated the ability of human amniotic fluid derived cells to substitute dermal fibroblasts and support epidermis formation and stratification in a humanized animal model. Methods: Dermo-epidermal skin grafts with either amniocytes or with fibroblasts in the dermis were compared in a rat model. Full-thickness skin wounds on the back of immuno-incompetent rats were covered with skin grafts with (1) amniocytes in the dermis, (2) fibroblasts in the dermis, or, (3) acellular dermis. Grafts were excised 7 and 21days post transplantation. Histology and immunofluorescence were performed to investigate epidermis formation, stratification, and expression of established skin markers. Results: The epidermis of skin grafts engineered with amniocytes showed near-normal anatomy, a continuous basal lamina, and a stratum corneum. Expression patterns for keratin 15, keratin 16, and Ki67 were similar to grafts with fibroblasts; keratin 1 expression was not yet fully established in all suprabasal cell layers, expression of keratin 19 was increased and not only restricted to the basal cell layer as seen in grafts with fibroblasts. In grafts with acellular dermis, keratinocytes did not survive. Conclusion: Dermo-epidermal skin grafts with amniocytes show near-normal physiological behavior suggesting that amniocytes substitute fibroblast function to support the essential cross-talk between mesenchyme and epithelia needed for epidermal stratification. This novel finding has considerable implications regarding tissue engineerin