The Principles of Proton Probe Microanalysis in Biology

The proton microprobe, more correctly described as an ion microprobe which operates at MeV energies, complements its parent instrument the electron microprobe. This paper compares the basic principles and performance of the two instruments and relates the evolution of biological analysis on such ion microprobes to that on electron microprobes, covering the development of sample handling techniques and of data handling techniques and comparing beam damage studies. The paper describes the variety of techniques available to the ion microprobe - the initial techniques of Energy Dispersive X-ray analysis, Rutherford Back Scattering and Nuclear Reaction Analysis and the rapid evolution of new techniques, from Scanning Transmission Ion Microscopy to 3-dimensional tomography. All of these new techniques required the advanced computerised data handling which has been a feature of ion microprobe development

Remarks on the fractal dimension of bi-space global and exponential attractors

Bi-spaces global and exponential attractors for the time continuous dynamical systems are considered and the bounds on their fractal dimension are discussed in the context of the smoothing properties of the system between appropriately chosen function spaces. A unified analytic semigroup approach to abstract parabolic equations is described and applications to the sample problems are given

Random attractors for degenerate stochastic partial differential equations

We prove the existence of random attractors for a large class of degenerate stochastic partial differential equations (SPDE) perturbed by joint additive Wiener noise and real, linear multiplicative Brownian noise, assuming only the standard assumptions of the variational approach to SPDE with compact embeddings in the associated Gelfand triple. This allows spatially much rougher noise than in known results. The approach is based on a construction of strictly stationary solutions to related strongly monotone SPDE. Applications include stochastic generalized porous media equations, stochastic generalized degenerate p-Laplace equations and stochastic reaction diffusion equations. For perturbed, degenerate p-Laplace equations we prove that the deterministic, infinite dimensional attractor collapses to a single random point if enough noise is added.Comment: 34 pages; The final publication is available at http://link.springer.com/article/10.1007%2Fs10884-013-9294-

SALL4 controls cell fate in response to DNA base composition

Contains fulltext : 232790.pdf (Publisher’s version ) (Open Access

Pectin-bioactive glass self-gelling, injectable composites with high antibacterial activity

The present work focuses on the development of novel injectable, self-gelling composite hydrogels based on two types of low esterified amidated pectins from citrus peels and apple pomace. Sol-gelderived, calcium-rich bioactive glass (BG) fillers in a particle form are applied as delivery vehicles for the release of Ca2+ ions to induce internal gelation of pectins. Composites were prepared by a relatively simple mixing technique, using 20% w/v BG particles of two different sizes (2.5 and <45 µm). Smaller particles accelerated pectin gelation slightly faster than bigger ones, which appears to result from the higher rate of Ca2+ ion release. µCT showed inhomogeneous distribution of the BG particles within the hydrogels. All composite hydrogels exhibited strong antibacterial activity against methicilin-resistant Staphylococcus aureus. The mineralization process of pectin-BG composite hydrogels occurred upon incubation in simulated body fluid for 28 days. In vitro studies demonstrated cytocompatibility of composite hydrogels with MC3T3-E1 osteoblastic cells

A Wasp Manipulates Neuronal Activity in the Sub-Esophageal Ganglion to Decrease the Drive for Walking in Its Cockroach Prey

BACKGROUND: The parasitoid Jewel Wasp hunts cockroaches to serve as a live food supply for its offspring. The wasp stings the cockroach in the head and delivers a cocktail of neurotoxins directly inside the prey's cerebral ganglia. Although not paralyzed, the stung cockroach becomes a living yet docile 'zombie', incapable of self-initiating spontaneous or evoked walking. We show here that such neuro-chemical manipulation can be attributed to decreased neuronal activity in a small region of the cockroach cerebral nervous system, the sub-esophageal ganglion (SEG). A decrease in descending permissive inputs from this ganglion to thoracic central pattern generators decreases the propensity for walking-related behaviors. METHODOLOGY AND PRINCIPAL FINDINGS: We have used behavioral, neuro-pharmacological and electrophysiological methods to show that: (1) Surgically removing the cockroach SEG prior to wasp stinging prolongs the duration of the sting 5-fold, suggesting that the wasp actively targets the SEG during the stinging sequence; (2) injecting a sodium channel blocker, procaine, into the SEG of non-stung cockroaches reversibly decreases spontaneous and evoked walking, suggesting that the SEG plays an important role in the up-regulation of locomotion; (3) artificial focal injection of crude milked venom into the SEG of non-stung cockroaches decreases spontaneous and evoked walking, as seen with naturally-stung cockroaches; and (4) spontaneous and evoked neuronal spiking activity in the SEG, recorded with an extracellular bipolar microelectrode, is markedly decreased in stung cockroaches versus non-stung controls. CONCLUSIONS AND SIGNIFICANCE: We have identified the neuronal substrate responsible for the venom-induced manipulation of the cockroach's drive for walking. Our data strongly support previous findings suggesting a critical and permissive role for the SEG in the regulation of locomotion in insects. By injecting a venom cocktail directly into the SEG, the parasitoid Jewel Wasp selectively manipulates the cockroach's motivation to initiate walking without interfering with other non-related behaviors

Antibody responses in furunculosis patients vaccinated with autologous formalin-killed Staphylococcus aureus

Autologous vaccines (short: autovaccines) have been used since the beginning of the 20th century to treat chronic staphylococcal infections, but their mechanisms of action are still obscure. This prospective pilot study involved four patients with furunculosis who were vaccinated with autologous formalin-killed Staphylococcus aureus cells. Vaccines were individually prepared from the infecting S. aureus strain and repeatedly injected subcutaneously in increasing doses over several months. We characterized the virulence gene repertoire and spa genotype of the infecting and colonising S. aureus strains. Serum antibody responses to secreted and surface-bound bacterial antigens were determined by two-dimensional immunoblotting and flow-cytometry based assays (Luminex®). All patients reported clinical improvement. Molecular characterization showed that all strains isolated from one patient over time belonged to the same S. aureus clone. Already before treatment, there was robust antibody binding to a broad range of staphylococcal antigens. Autovaccination moderately boosted the IgG response to extracellular antigens in two patients, while the antibody response of the other two patients was not affected. Similarly, vaccination moderately enhanced the antibody response against some staphylococcal surface proteins, e.g. ClfA, ClfB, SdrD and SdrE. In summary, autovaccination only slightly boosted the pre-existing serum antibody response, predominantly to bacterial surface antigens

Modelling opinion formation by means of kinetic equations

In this chapter, we review some mechanisms of opinion dynamics that can be modelled by kinetic equations. Beside the sociological phenomenon of compromise, naturally linked to collisional operators of Boltzmann kind, many other aspects, already mentioned in the sociophysical literature or no, can enter in this framework. While describing some contributions appeared in the literature, we enlighten some mathematical tools of kinetic theory that can be useful in the context of sociophysics