Hyperbaric oxygen therapy for the prevention of radiation-induced tissue injury in the head and neck region.

__Abstract__ Each year, more than 500.000 cases of head and neck cancer (HNC) occur worldwide. More than half of these are oral cavity cancers, while the rest comprises pharyngeal and laryngeal cancers (Figure 1). The vast majority (~90%) of HNC diagnoses are squamous cell carcinomas, originating from the epithelium. HNC can be divided into three clinical stages: early, locoregionally advanced and metastatic, of which more than 50% belongs to the second category. Metastases are seen in the lymph nodes of the neck, and are often the first sign of the disease. Morbidity rates are close to 25% but are highly dependent on staging. Early detection exponentially increases the chance of curing. Alcohol consumption, tobacco smoking and human papillomavirus infection are the most important risk factors (alcohol and tobacco accounting for 75% of HNCs)

The effect of hemicelluloses on the mechanical properties of individual pulp fibers.

Ph.D

Fc Receptors for IgE and Interleukin-4 Induced IgE and IgG4 Secretion

IgE binds to two types of Fc receptors, called Fc∈R1 (or high-affinity Fc∈R) and Fc∈R2 (or low-affinity Fc∈R). The Fc∈R1 is composed of four polypeptide chains, one α, one β, and two γ chains. The α chain contains the IgE binding site and is a member of the immunoglobulin supergene family. The Fc∈R2, also called CD23, consists of one polypeptide chain which shows homology to animal lectin receptors. Fc∈R1 are expressed on mast cells and basophils. Crosslinking of the Fc∈R1 induces immediate release of mediators of inflammation such as histamine and leukotrienes and delayed secretion of interleukins 4, 5, and 6. Fc∈R2 are expressed on resting μδ+ B cells, monocytes/macrophages (MΦ), eosinophils, and platelets but rarely on T cells. Interleukin-4 up-regulates Fc∈R2 expression on B cells and MΦ. The functions of Fc∈R2 on the different cell types are not fully established and are controversial. Fc∈R2 on MΦ, eosinophils, and platelets mediate cytotoxicity to schistosomules, enhance phagocytosis, and induce the release of granule enzymes. However, MΦ from patients with atopic dermatitis expressing significantly more Fc∈R2 than MΦ from normals do not release more leukotriene C4, prostaglandin E2, or β-glucuronidase after incubation with aggregated IgE than normal monocytes. Furthermore, aggregated IgG1 is much more efficient than IgE in inducing mediator release from MΦ and IgG1 antibodies are not known to induce immediate-type hypersensitivity reactions. Therefore, definitive proof that Fc∈R2 are involved in the pathogenesis of allergic disorders is still lacking. IL-4 appears to play a central role in immediate-type hypersensitivity. It induces human B cells to secrete IgE and IgG4, Ig isotypes typical for antibodies to helminthic parasites and allergens. IL-4 stimulates mast cell growth and up-regulates Fc∈R2 expression. Interferon-γ and IL-2 inhibit the IL-4-induced IgG4 and IgE secretion. Whether the abnormally high IgE antibody production in atopic patients is the result of overproduction of IL-4 or deficient IFN-γ/IL-2 production is presently unknown

2,4-DINITROPHENYL RECEPTORS ON MOUSE THYMUS AND SPLEEN CELLS

A higher percentage of specific antigen-binding cells can be detected not only in normal CBA/J mouse spleen cell preparations (0.99%), but also in the normal thymus cell preparations (0.15%) with the use of [125I]2,4-dinitrophenyl-human IgG (DNP-HGG) as compared with most other antigens employed under similar conditions. The receptors on these cells are mainly specific for the DNP group as shown by the inhibition studies with DNP-lysine and the other DNP conjugates. In addition, it was shown by the inhibition studies with DNP-lysine that the thymus cells seem to have a lower avidity for DNP than the spleen cells. Preincubation of cell suspensions with antisera to immunoglobulins showed that the DNP-HGG antigen-binding cells in the thymus are inhibited predominantly with anti-µ-chain serum and the spleen cells with both anti-µ-chain and anti-γ-chain sera; both cell populations were also significantly inhibited with the antisera to κ-chains and Fab fragments. These data indicate that the nature of the receptor on the T cell differs from that on the majority of spleen cells

Gaussian approximation for finitely extensible bead-spring chains with hydrodynamic interaction

The Gaussian Approximation, proposed originally by Ottinger [J. Chem. Phys., 90 (1) : 463-473, 1989] to account for the influence of fluctuations in hydrodynamic interactions in Rouse chains, is adapted here to derive a new mean-field approximation for the FENE spring force. This "FENE-PG" force law approximately accounts for spring-force fluctuations, which are neglected in the widely used FENE-P approximation. The Gaussian Approximation for hydrodynamic interactions is combined with the FENE-P and FENE-PG spring force approximations to obtain approximate models for finitely-extensible bead-spring chains with hydrodynamic interactions. The closed set of ODE's governing the evolution of the second-moments of the configurational probability distribution in the approximate models are used to generate predictions of rheological properties in steady and unsteady shear and uniaxial extensional flows, which are found to be in good agreement with the exact results obtained with Brownian dynamics simulations. In particular, predictions of coil-stretch hysteresis are in quantitative agreement with simulations' results. Additional simplifying diagonalization-of-normal-modes assumptions are found to lead to considerable savings in computation time, without significant loss in accuracy.Comment: 26 pages, 17 figures, 2 tables, 75 numbered equations, 1 appendix with 10 numbered equations Submitted to J. Chem. Phys. on 6 February 200

Cryptocurrency Competition and Market Concentration in the Presence of Network Effects

When network products and services become more valuable as their userbase grows (network effects), this tendency can become a major determinant of how they compete with each other in the market and how the market is structured. Network effects are traditionally linked to high market concentration, early-mover advantages, and entry barriers, and in the market they have also been used as a valuation tool. The recent resurgence of Bitcoin has been partly attributed to network effects, too. We study the existence of network effects in six cryptocurrencies from their inception to obtain a high-level overview of the application of network effects in the cryptocurrency market. We show that, contrary to the usual implications of network effects, they do not serve to concentrate the cryptocurrency market, nor do they accord any one cryptocurrency a definitive competitive advantage, nor are they consistent enough to be reliable valuation tools. Therefore, while network effects do occur in cryptocurrency networks, they are not (yet) a defining feature of the cryptocurrency market as a whole