A proteomic investigation of Fusobacterium nucleatum alkaline-induced biofilms

Background: The Gram negative anaerobe Fusobacterium nucleatum has been implicated in the aetiology of periodontal diseases. Although frequently isolated from healthy dental plaque, its numbers and proportion increase in plaque associated with disease. One of the significant physico-chemical changes in the diseased gingival sulcus is increased environmental pH. When grown under controlled conditions in our laboratory, F. nucleatum subspecies polymorphum formed mono-culture biofilms when cultured at pH 8.2. Biofilm formation is a survival strategy for bacteria, often associated with altered physiology and increased virulence. A proteomic approach was used to understand the phenotypic changes in F. nucleatum cells associated with alkaline induced biofilms. The proteomic based identification of significantly altered proteins was verified where possible using additional methods including quantitative real-time PCR (qRT-PCR), enzyme assay, acidic end-product analysis, intracellular polyglucose assay and Western blotting. Results: Of 421 proteins detected on two-dimensional electrophoresis gels, spot densities of 54 proteins varied significantly (p < 0.05) in F. nucleatum cultured at pH 8.2 compared to growth at pH 7.4. Proteins that were differentially produced in biofilm cells were associated with the functional classes; metabolic enzymes, transport, stress response and hypothetical proteins. Our results suggest that biofilm cells were more metabolically efficient than planktonic cells as changes to amino acid and glucose metabolism generated additional energy needed for survival in a sub-optimal environment. The intracellular concentration of stress response proteins including heat shock protein GroEL and recombinational protein RecA increased markedly in the alkaline environment. A significant finding was the increased abundance of an adhesin, Fusobacterial outer membrane protein A (FomA). This surface protein is known for its capacity to bind to a vast number of bacterial species and human epithelial cells and its increased abundance was associated with biofilm formation. Conclusion: This investigation identified a number of proteins that were significantly altered by F. nucleatum in response to alkaline conditions similar to those reported in diseased periodontal pockets. The results provide insight into the adaptive mechanisms used by F. nucleatum biofilms in response to pH increase in the host environment.Jactty Chew, Peter S Zilm, Janet M Fuss and Neville J Gull

Impact of edge-removal on the centrality betweenness of the best spreaders

The control of epidemic spreading is essential to avoid potential fatal consequences and also, to lessen unforeseen socio-economic impact. The need for effective control is exemplified during the severe acute respiratory syndrome (SARS) in 2003, which has inflicted near to a thousand deaths as well as bankruptcies of airlines and related businesses. In this article, we examine the efficacy of control strategies on the propagation of infectious diseases based on removing connections within real world airline network with the associated economic and social costs taken into account through defining appropriate quantitative measures. We uncover the surprising results that removing less busy connections can be far more effective in hindering the spread of the disease than removing the more popular connections. Since disconnecting the less popular routes tend to incur less socio-economic cost, our finding suggests the possibility of trading minimal reduction in connectivity of an important hub with efficiencies in epidemic control. In particular, we demonstrate the performance of various local epidemic control strategies, and show how our approach can predict their cost effectiveness through the spreading control characteristics.Comment: 11 pages, 4 figure

A Historical Analysis Of The Social Security Program In The United States

Economic security means that sufficient provision has been made to furnish at least the basic material needs of an individual or family. Social insurance is one of the basic instruments used to combat economic insecurity. It is not easy to define economic insecurity but there are several basic factors involved. The loss of income is a factor that could lead to economic insecurity. Job separation arising from old age, accidental injury, sickness and death of the wage earner are the major forces giving rise to economic insecurity. Society has attacked the problem of economic insecurity in several ways. Regulation, alleviation, and prevention have been established as the basic methods used to approach the problems of economic security. The term social security is new in our society. Social security is a term which involves social insurance, social assistance, and related public programs. The United States was not the first country to have a social security-type program but it was not until the passage of the social. Security Act in the United States on August 14, 1935, that the term became common throughout the world. The main objective of social security is to replace part of the earnings that have stopped or reduced because the worker retires, dies, or becomes disabled. Social security is based on similar principles as private insurance, with elements to accomplish its social purpose and to keep it the least expensive. There are certain differences between commercial insurance and private insurance on the one hand and social security insurance, on the other; but the general idea is the same. Under the social security program, the whole system is operated by the federal government and some people get more benefits than others in relation to their contributions. Several services are provided through Federal grants to States under the Social Security Act

Exploring the S-Matrix of Massless Particles

We use the recently proposed generalised on-shell representation for scattering amplitudes and a consistency test to explore the space of tree-level consistent couplings in four-dimensional Minkowski spacetime. The extension of the constructible notion implied by the generalised on-shell representation, i.e. the possibility to reconstruct at tree level all the scattering amplitudes from the three-particle ones, together with the imposition of the consistency conditions at four-particle level, allow to rediscover all the known theories and their algebra structure, if any. Interestingly, this analysis seems to leave room for high-spin couplings, provided that at least the requirement of locality is weakened. We do not claim to have found tree-level consistent high-spin theories, but rather that our methods show signatures of them and very likely, with a suitable modification, they can be a good framework to perform a systematic search.Comment: 44 pages, 1 figur

Transition from collisionless to collisional MRI

Recent calculations by Quataert et al. (2002) found that the growth rates of the magnetorotational instability (MRI) in a collisionless plasma can differ significantly from those calculated using MHD. This can be important in hot accretion flows around compact objects. In this paper we study the transition from the collisionless kinetic regime to the collisional MHD regime, mapping out the dependence of the MRI growth rate on collisionality. A kinetic closure scheme for a magnetized plasma is used that includes the effect of collisions via a BGK operator. The transition to MHD occurs as the mean free path becomes short compared to the parallel wavelength 2\pi/k_{\Par}. In the weak magnetic field regime where the Alfv\'en and MRI frequencies $\omega$ are small compared to the sound wave frequency k_{\Par} c_0, the dynamics are still effectively collisionless even if $\omega \ll \nu$, so long as the collision frequency \nu \ll k_{\Par} c_{0}; for an accretion flow this requires \nu \lsim \Omega \sqrt{\beta}. The low collisionality regime not only modifies the MRI growth rate, but also introduces collisionless Landau or Barnes damping of long wavelength modes, which may be important for the nonlinear saturation of the MRI.Comment: 20 pages, 4 figures, submitted to ApJ with a clearer derivation of anisotropic pressure closure from drift kinetic equatio

U(1)-decoupling, KK and BCJ relations in N=4\mathcal{N}=4 SYM

We proved the color reflection relation, U(1)-decoupling, Kleiss-Kuijf and Bern-Carrasco-Johansson relation for color-ordered $\mathcal{N}=4$ Super Yang-Mills theory using $\mathcal{N}=4$ SYM version BCFW recursion relation, which depends only on the general properties of super-amplitudes. This verified the conjectured matter fields BCJ relation. We also show that color reflection relation and U(1)-decoupling relation are special cases of KK relation, if we consider the KK relation as a general relation, then the former two relations come out naturally as the special cases.Comment: 17 page

Preschoolers' attribution of affect to music: a comparison between vocal and instrumental performance

Research has shown inconsistent results concerning the ability of young children to identify musical emotion. This study explores the influence of the type of musical performance (vocal vs. instrumental) on children’s affect identification. Using an independent-group design, novel child-directed music was presented in three conditions: instrumental, vocal-only, and song (instrumental plus vocals) to 3- to 6-year-olds previously screened for language development (n = 76). A forced-choice task was used in which children chose a face expressing the emotion matching each musical track. All performance conditions comprised ‘happy’ (major mode/fast tempo) and ‘sad’ (minor mode/slow tempo) tracks. Nonsense syllables rather than words were used in the vocals in order to avoid the influence of lyrics on children's decisions. The results showed that even the younger children were able to identify correctly the intended emotion in music, although ‘happy’ music was more readily recognized and recognition appeared facilitated in the instrumental condition. Performance condition interacted with gender