Surface electrons at plasma walls

In this chapter we introduce a microscopic modelling of the surplus electrons on the plasma wall which complements the classical description of the plasma sheath. First we introduce a model for the electron surface layer to study the quasistationary electron distribution and the potential at an unbiased plasma wall. Then we calculate sticking coefficients and desorption times for electron trapping in the image states. Finally we study how surplus electrons affect light scattering and how charge signatures offer the possibility of a novel charge measurement for dust grains.Comment: To appear in Complex Plasmas: Scientific Challenges and Technological Opportunities, Editors: M. Bonitz, K. Becker, J. Lopez and H. Thomse

Linear-response theory and lattice dynamics: a muffin-tin orbital approach

A detailed description of a method for calculating static linear-response functions in the problem of lattice dynamics is presented. The method is based on density functional theory and it uses linear muffin-tin orbitals as a basis for representing first-order corrections to the one-electron wave functions. As an application we calculate phonon dispersions in Si and NbC and find good agreement with experiments.Comment: 18 pages, Revtex, 2 ps figures, uuencoded, gzip'ed, tar'ed fil

Suppression of Radiation-Induced Salivary Gland Dysfunction by IGF-1

Radiation is a primary or secondary therapeutic modality for treatment of head and neck cancer. A common side effect of irradiation to the neck and neck region is xerostomia caused by salivary gland dysfunction. Approximately 40,000 new cases of xerostomia result from radiation treatment in the United States each year. The ensuing salivary gland hypofunction results in significant morbidity and diminishes the effectiveness of anti-cancer therapies as well as the quality of life for these patients. Previous studies in a rat model have shown no correlation between induction of apoptosis in the salivary gland and either the immediate or chronic decrease in salivary function following gamma-radiation treatment.A significant level of apoptosis can be detected in the salivary glands of FVB mice following gamma-radiation treatment of the head and neck and this apoptosis is suppressed in transgenic mice expressing an activated mutant of Akt (myr-Akt1). Importantly, this suppression of apoptosis in myr-Akt1 mice preserves salivary function, as measured by saliva output, three and thirty days after gamma-radiation treatment. In order to translate these studies into a preclinal model we found that intravenous injection of IGF1 stimulated activation of endogenous Akt in the salivary glands in vivo. A single injection of IGF1 prior to exposure to gamma-radiation diminishes salivary acinar cell apoptosis and completely preserves salivary gland function three and thirty days following irradiation.These studies suggest that apoptosis of salivary acinar cells underlies salivary gland hypofunction occurring secondary to radiation of the head and neck region. Targeted delivery of IGF1 to the salivary gland of patients receiving head and neck irradiation may be useful in reducing or eliminating xerostomia and restoring quality of life to these patients

WNT signalling in prostate cancer

Genome sequencing and gene expression analyses of prostate tumours have highlighted the potential importance of genetic and epigenetic changes observed in WNT signalling pathway components in prostate tumours-particularly in the development of castration-resistant prostate cancer. WNT signalling is also important in the prostate tumour microenvironment, in which WNT proteins secreted by the tumour stroma promote resistance to therapy, and in prostate cancer stem or progenitor cells, in which WNT-β-catenin signals promote self-renewal or expansion. Preclinical studies have demonstrated the potential of inhibitors that target WNT receptor complexes at the cell membrane or that block the interaction of β-catenin with lymphoid enhancer-binding factor 1 and the androgen receptor, in preventing prostate cancer progression. Some WNT signalling inhibitors are in phase I trials, but they have yet to be tested in patients with prostate cancer

Radiation Produces Irreversible Chronic Dysfunction in the Submandibular Glands of the Rat

The exposure to high doses of ionizing radiation during radiotherapy results in severe morphological and functional alterations of the salivary glands, such as xerostomia. In the present study we investigated the chronic effect of a single radiation dose of 15 Gray (Gy) limited to head and neck on rat salivary gland function (salivary secretion and gland mass) and histology. Results indicate that norepinephrine (NE)-induced salivary secretion was reduced significantly at 30, 90, 180 and 365 days after the administration of a single dose of 15 Gy of ionizing radiation compared to non-irradiated animals. The maximal secretory response was reduced by 33% at 30 and 90 days post irradiation. Interestingly, a new fall in the salivary response to NE was observed at 180 days and was maintained at 365 days post irradiation, showing a 75% reduction in the maximal response. The functional fall of the salivary secretion observed at 180 days post irradiation was not only associated with a reduction of gland mass but also to an alteration of the epithelial architecture exhibiting a changed proportion of ducts and acini, loss of eosinophilic secretor granular material, and glandular vacuolization and fibrosis. On the basis of the presented results, we conclude that ionizing radiation produces irreversible and progressive alterations of submandibular gland (SMG) function and morphology that leads to a severe salivary hypo-function

Differentiation of Gram-Negative Bacterial Aerosol Exposure Using Detected Markers in Bronchial-Alveolar Lavage Fluid

The identification of biosignatures of aerosol exposure to pathogens has the potential to provide useful diagnostic information. In particular, markers of exposure to different types of respiratory pathogens may yield diverse sets of markers that can be used to differentiate exposure. We examine a mouse model of aerosol exposure to known Gram negative bacterial pathogens, Francisella tularensis novicida and Pseudomonas aeruginosa. Mice were subjected to either a pathogen or control exposure and bronchial alveolar lavage fluid (BALF) was collected at four and twenty four hours post exposure. Small protein and peptide markers within the BALF were detected by matrix assisted laser desorption/ionization (MALDI) mass spectrometry (MS) and analyzed using both exploratory and predictive data analysis methods; principle component analysis and degree of association. The markers detected were successfully used to accurately identify the four hour exposed samples from the control samples. This report demonstrates the potential for small protein and peptide marker profiles to identify aerosol exposure in a short post-exposure time frame

Reverse Engineering a Signaling Network Using Alternative Inputs

One of the goals of systems biology is to reverse engineer in a comprehensive fashion the arrow diagrams of signal transduction systems. An important tool for ordering pathway components is genetic epistasis analysis, and here we present a strategy termed Alternative Inputs (AIs) to perform systematic epistasis analysis. An alternative input is defined as any genetic manipulation that can activate the signaling pathway instead of the natural input. We introduced the concept of an “AIs-Deletions matrix” that summarizes the outputs of all combinations of alternative inputs and deletions. We developed the theory and algorithms to construct a pairwise relationship graph from the AIs-Deletions matrix capturing both functional ordering (upstream, downstream) and logical relationships (AND, OR), and then interpreting these relationships into a standard arrow diagram. As a proof-of-principle, we applied this methodology to a subset of genes involved in yeast mating signaling. This experimental pilot study highlights the robustness of the approach and important technical challenges. In summary, this research formalizes and extends classical epistasis analysis from linear pathways to more complex networks, facilitating computational analysis and reconstruction of signaling arrow diagrams

Phonons and related properties of extended systems from density-functional perturbation theory

This article reviews the current status of lattice-dynamical calculations in crystals, using density-functional perturbation theory, with emphasis on the plane-wave pseudo-potential method. Several specialized topics are treated, including the implementation for metals, the calculation of the response to macroscopic electric fields and their relevance to long wave-length vibrations in polar materials, the response to strain deformations, and higher-order responses. The success of this methodology is demonstrated with a number of applications existing in the literature.Comment: 52 pages, 14 figures, submitted to Review of Modern Physic

Omanicotyle heterospina n. gen. et n. comb. (Monogenea: Microcotylidae) from the gills of Argyrops spinifer (Forsskal) (Teleostei: Sparidae) from the Sea of Oman

Background: The Sultanate of Oman's aquaculture industry is expanding with an on-going assessment of potential new fish species for culture. The king soldier bream, Argyrops spinifer (Forsskål) (Sparidae), is one such species that is under consideration. During a routine health assessment of specimens caught in the Sea of Oman throughout the period November 2009 to March 2011, a number of gill polyopisthocotylean monogeneans were recovered. Methods: A subsequent study of the monogeneans using a range of morphology-based approaches indicated that these were Bivagina heterospina Mamaev et Parukhin, 1974. In the absence of pre-existing molecular data, an expanded description of this species is provided, including a differential diagnosis with other species and genera belonging to the subfamily Microcotylinae Monticelli, 1892 with the subsequent movement of this species to a new genus to accommodate it. Results: The polyopisthocotyleans collected from the gills of A. spinifer appear to be unique within the family Microcotylidae Taschenberg, 1879 in that, morphologically, they possess a pair of large, muscular vaginae each armed with a full crown of 16-18 robust spines and a unique dorsal region of folded tegument, which permits their discrimination from species of Bivagina Yamaguti, 1963. Sequencing of the SSU rDNA (complete 1968 bp) and LSU rDNA (partial 949 bp) places the specimens collected during this study within the subfamily Microcotylinae, but the LSU rDNA sequence differs from Bivagina and also from other microcotylid genera. Morphological features of B. heterospina sensu Mamaev et Parukhin, 1974 and the specimens collected from the current study are consistent with one another and represent a single species. The vaginal armature of these worms is unique and differs from all other genera within the Microcotylinae, including Bivagina, and its movement to Omanicotyle n. gen. to accommodate this species is proposed. Conclusions: A new genus, Omanicotyle n. gen., is erected to accommodate Omanicotyle [Bivagina] heterospina n. comb. which represents the first monogenean to be described from Omani marine waters. Given the pathogenic potential of microcotylids on captive held fish stocks, a full assessment of Omanicotyle heterospina n. gen. et n. comb. is now required before large-scale production commences