On diffraction within a dielectric medium as an example of the Minkowski formulation of optical momentum

The Abraham-Minkowski dilemma relates to the disputed value of the optical momentum within a dielectric medium and whether the free-space value should be divided (Abraham) or multiplied (Minkowski) by the refractive index. Although undoubtedly simplistic, these two approaches provide intuitive insight to many subtle problems in optical physics. This paper reviews a modified version of the Einstein box argument that supports an Abraham formulation, then considers diffraction within a dielectric medium and shows it supports a simple Minkowski formulation, i.e. that the optical momentum should be multiplied by the refractive index

Evaluation of liposomes coated with a pH responsive polymer

Liposomes have been coated with the pH responsive polymer, Eudragit S100, and the formulation's potential for lower gastrointestinal (GI) targeting following oral administration assessed. Cationic liposomes were coated with the anionic polymer through simple mixing. The evolution of a polymer coat was studied using zeta potential measurements and laser diffraction size analysis. Further evidence of an association between polymer and liposome was obtained using light and cryo scanning electron microscopy. Drug release studies were carried out at pH 1.4, pH 6.3 and pH 7.8, representing the pH conditions of the stomach, small intestine and ileocaecal junction, respectively.\ud \ud The polymer significantly reduced liposomal drug release at pH 1.4 and pH 6.3 but drug release was equivalent to the uncoated control at pH 7.8, indicating that the formulation displayed appropriate pH responsive release characteristics. While the coating layer was not able to withstand the additional challenge of bile salts this reinforces the importance of evaluating these types of formulations in more complex media.\ud \u

The importance of being alkaline

The earliest forms of "protolife" on Earth must have been able to reproduce and replicate; it is likely that they were also cellular. How might such systems have formed? In his Perspective, Russell highlights the report by Hanczyc et al., who show that clay particles can catalyze the formation of lipid vesicles. These particles also adsorb RNA. If the vesicles are forced to divide, RNA is distributed among the daughter vesicles. Similar conditions to those used in the experiments may have existed at mounds created by alkaline, hydrothermal seepages on the ancient ocean floor. However, instead of lipids, polypeptides formed from amino acids may have formed the first organic membranes

Stress intensity In a thermoroll

During the manufacture of coated paper products, a paper-making stock consisting of water and 1% or less wood fibers is prepared by chemically or mechanically separating the fibers from wood. A screening process removes most of the water; the remainder is removed through pressing against felts and contact drying. The web is further densified by passing it through high pressure calender rolls, resulting in about a two-fold decrease in caliper of the pressed and dried paper. The web may then pass through a number of calender nips. This last stage of densification involves high temperatures and pressures that lead to high stresses in the roll material. A stack consists of two rolls: one has a polymeric elastomer covering, the other is a solid iron alloy (the thermoroll). It is our task to estimate the stresses in the thermoroll under standard operating conditions, and determine whether it is possible, under certain conditions, for cracking or roll failure to occur. The main focus of our group was to calculate the temperature gradient in the thermoroll and to determine whether this gradient can lead to an intensification of stress in the nip region

The effect of ethnic factor on cephalic index in 17-20 years old females of north of Iran [Efecto del factor étnico en el índice cefálico en mujeres entre 17 y 20 años de edad del norte de Irán]

Cephalic index and head shape are affected by geographical, gender, age, racial and ethnic factors. This study was carried out to determine cephalic index and head shape in 17-20 years old female in Gorgan, North of Iran. This descriptive and cross sectional study is undertaken on 410 normal 17-20 years old female (Turkman group: n=203, Fars group: n=207). The study was done by classic cephalometry in Gorgan North of Iran. Means and SD of cephalic index was 85 ± 4.5 and 82.8 ± 3.6 in native Fars and Turkman groups, respectively. Dominant and rare type of head shape in native Fars group were hyperbrachycephalic (53.6%) and dolichocephalic (15%), and in Turkman group were brachycephalic (58.1%) and dolichocephalic (0.05%), respectively. With noticing of our results and other studies in the world, we can conclude that the role of ethnic factor on head dimensions. © 2007 Sociedad Chilena de Anatomía

The variation of head shapes in 17-20 years old native fars male in Gorgan-North of Iran

Cephalic index and head shape are affected by geographical, gender, age and racial factors. This study carried out to determine cephalic index and head shape in 17-20 years old native Fars male in Gorgan, North of Iran. This descriptive study was done on 200 of 17-20 years old male native Fars by classic cephalometry in Gorgan, North of Iran. Mean and SD of cephalic index was 84.8 ± 6.9. The head shape of 52% of individuals was hyperbrachycephalic, 25% brachycephalic, 21.5% mesocephalic and 1.5% dolichocephalic. Native Fars individuals showed typical hyperbrachycephalic. In comparing to other studies in world, we can conclude that the role of racial/ethnic factor in cephalic diameters. © 2006 Sociedad Chilena de Anatomía

Libraries and the management of research data

A discussion of the role of university libraries in the management of digital research data outputs. Reviews some of the recent history of progress in this area from a UK perspective, with reference to international developments

Stepping out of the picture: Using drama in storyline topics

This chapter discusses using drama in storyline topics