Study of Virus-Like Particles in Male Mice Carrying Mammary Tumour Agent

SEVERAL investigations had been conducted in order to study the origin and distribution of mammary tumour agent (MTA) in various organs of high cancer strain mice. It (MTA) is known to be harboured also by the males of the same strains in their reproductive organs and accessory glands (Andervont and Dunn, 1948a) from which it can be transmitted to virus susceptible females in the course of repeated mating to these same females and eventually to their young ones (Andervont and Dunn, 1948b) through the milk (Bittner, 1952). Muhlbock (1950) established the presence of this agent in the sperms passed from the end of the epididymis. He (Muhlbock, 1952) had experimentally shown that agent free females develop mammary tumours after mating with the males of high-cancer strain. He had also shown that the seminal vesicle of such males shows biological activity for these agents and can produce mammary tumours in the females. Recently Feldman (1963) has shown virus-like particles within the endoplasmic reticulum of the epididymis of both high-cancer strain, and agent free males. Further investigations in this line of work were thought to be quite pertinent

THz Time Domain Characterization of Human Skin Tissue for Nano-Electromagnetic Communication

This paper presents an experimental investigation of excised human skin tissue material parameters by THz Time Domain Spectroscopy in the band 0.1-2.5 THz. The results are used to evaluate the channel path loss Nano-electromagnetic communication. Refractive index and absorption coefficient values are evaluated for dermis layer of the human skin. Results obtained illustrate the effect of hydrated tissue on channel parameters and provide the optimum distance, which can be utilized for effective communication inside the human skin

Magnetoresistance of atomic-sized contacts: an ab-initio study

The magnetoresistance (MR) effect in metallic atomic-sized contacts is studied theoretically by means of first-principle electronic structure calculations. We consider three-atom chains formed from Co, Cu, Si, and Al atoms suspended between semi-infinite Co leads. We employ the screened Korringa-Kohn-Rostoker Green's function method for the electronic structure calculation and evaluate the conductance in the ballistic limit using the Landauer approach. The conductance through the constrictions reflects the spin-splitting of the Co bands and causes high MR ratios, up to 50%. The influence of the structural changes on the conductance is studied by considering different geometrical arrangements of atoms forming the chains. Our results show that the conductance through s-like states is robust against geometrical changes, whereas the transmission is strongly influenced by the atomic arrangement if p or d states contribute to the current.Comment: Revised version, presentation of results is improved, figure 2 is splitted to two figure

Excitons in boron nitride nanotubes: dimensionality effects

We show that the optical absorption spectra of boron nitride (BN) nanotubes are dominated by strongly bound excitons. Our first-principles calculations indicate that the binding energy for the first and dominant excitonic peak depends sensitively on the dimensionality of the system, varying from 0.7 eV in bulk hexagonal BN via 2.1 eV in the single sheet of BN to more than 3 eV in the hypothetical (2,2) tube. The strongly localized nature of this exciton dictates the fast convergence of its binding energy with increasing tube diameter towards the sheet value. The absolute position of the first excitonic peak is almost independent of the tube radius and system dimensionality. This provides an explanation for the observed "optical gap" constancy for different tubes and bulk hBN [R. Arenal et al., to appear in Phys. Rev. Lett. (2005)].Comment: 5 pages, 2 figure

From social machines to social protocols:Software engineering foundations for sociotechnical systems

The overarching vision of social machines is to facilitate social processes by having computers provide administrative support. We conceive of a social machine as a sociotechnical system (STS): a software-supported system in which autonomous principals such as humans and organizations interact to exchange information and services. Existing approaches for social machines emphasize the technical aspects and inadequately support the meanings of social processes, leaving them informally realized in human interactions. We posit that a fundamental rethinking is needed to incorporate accountability, essential for addressing the openness of the Web and the autonomy of its principals. We introduce Interaction-Oriented Software Engineering (IOSE) as a paradigm expressly suited to capturing the social basis of STSs. Motivated by promoting openness and autonomy, IOSE focuses not on implementation but on social protocols, specifying how social relationships, characterizing the accountability of the concerned parties, progress as they interact. Motivated by providing computational support, IOSE adopts the accountability representation to capture the meaning of a social machine’s states and transitions. We demonstrate IOSE via examples drawn from healthcare. We reinterpret the classical software engineering (SE) principles for the STS setting and show how IOSE is better suited than traditional software engineering for supporting social processes. The contribution of this paper is a new paradigm for STSs, evaluated via conceptual analysis

Paediatric burns in a rural South African district hospital

Objectives. To describe the epidemiology, clinical features, management and outcome of children with burns admitted to a rural district hospital. Design. A retrospective analysis of the case notes of consecutive cases of paediatric burns. Setting. Hlabisa Hospital, KwaZulu-Natal - a 450-bed rural district hospital serving approximately 200 000 people. Subjects. All cases of paediatric burns (age < 12 years) admitted to Hlabisa Hospital in 1994. Main outcome measures. Number of admissions, month of admission, age, sex, time to presentation, site of burn, complications, number of surgical procedures, adherence to management protocol and outcome. Results. One hundred and forty-nine children presented to the outpatient department in 1994 and 88 (59%) were admitted, The median age of those admitted was 36 months with 66 (75%) aged less than 5 years; 42 (48%) were boys, Thirty-nine children (44%) were admitted during the four winter months of May to August, The average interval from the tirne of the burn to presentation at hospital was 42 hours (range 1 - 120). Sixty-eight burns (77%) were due to hot fluid or food burning the legs, trunk or arms, There was a high level of morbidity, Nineteen (22%) children developed wound infections, 5 (6%) developed contractures and 20 (23%) required a total of 32 surgical procedures, There was 1 death, Burns were responsible for more paediatric patient days spent in hospital than any condition other than malnutrition, and a longer length of stay was associated with delay in presentation, Children presenting within 24 hours of the burn had a mean length of stay of 12.8 days, compared with 25.2 days (P = 0.03) for children presenting 24 hours or more after the burn. Twenty of the 22 children who stayed for longer than 3 weeks or who required transfer were judged to have been managed inadequately in at least one respect compared with 3 of 48 who were discharged within 2 weeks or not transferred (P < 0.001). Conclusion. This study shows that paediatric burns are an important cause of morbidity and contribute significantly to inpatient stay in this rural setting. The lengthy delay from time of burn to presentation at hospital is of serious concern and our results show that this delay is associated with increased hospital stay. As most burns were due to spillage of hot fluids or food there seems to be significant potential for preventive interventions. Community-based studies would help to estimate the true incidence of burns and would contribute to an understanding of the reasons for delay in presentation. The information gathered is being used to inform the development of a burns prevention programme.4 page(s

Magneto-mechanical interplay in spin-polarized point contacts

We investigate the interplay between magnetic and structural dynamics in ferromagnetic atomic point contacts. In particular, we look at the effect of the atomic relaxation on the energy barrier for magnetic domain wall migration and, reversely, at the effect of the magnetic state on the mechanical forces and structural relaxation. We observe changes of the barrier height due to the atomic relaxation up to 200%, suggesting a very strong coupling between the structural and the magnetic degrees of freedom. The reverse interplay is weak, i.e. the magnetic state has little effect on the structural relaxation at equilibrium or under non-equilibrium, current-carrying conditions.Comment: 5 pages, 4 figure

Graphitic-BN Based Metal-free Molecular Magnets From A First Principle Study

We perform a first principle calculation on the electronic properties of carbon doped graphitic boron nitride graphitic BN. It was found that carbon substitution for either boron or nitrogen atom in graphitic BN can induce spontaneous magnetization. Calculations based on density functional theory with the local spin density approximation on the electronic band structure revealed a spin polarized, dispersionless band near the Fermi energy. Spin density contours showed that the magnetization density originates from the carbon atom. The magnetization can be attributed to the carbon 2p electron. Charge density distribution shows that the carbon atom forms covalent bonds with its three nearest neighbourhood. The spontaneous magnetization survives the curvature effect in BN nanotubes, suggesting the possibility of molecular magnets made from BN. Compared to other theoretical models of light-element or metal-free magnetic materials, the carbon-doped BN are more experimentally accessible and can be potentially useful.Comment: 8 pages, 4 figure