Buckling of a beam extruded into highly viscous fluid

Inspired by microscopic paramecies which use trichocyst extrusion to propel themselves away from thermal aggressions, we propose a macroscopic experiment to study the stability of a slender beam extruded in a highly viscous fluid. Piano wires were extruded axially at constant speed in a tank filled with corn syrup. The force necessary to extrude the wire was measured to increase linearly at first until the compressive viscous force causes the wire to buckle. A numerical model, coupling a lengthening elastica formulation with resistive force theory, predicts a similar behaviour. The model is used to study the dynamics at large time when the beam is highly deformed. It is found that at large time, a large deformation regime exists in which the force necessary to extrude the beam at constant speed becomes constant and length-independent. With a proper dimensional analysis, the beam can be shown to buckle at a critical length based on the extrusion speed, the bending rigidity and the dynamic viscosity of the fluid. Hypothesising that the trichocysts of paramercies must be sized to maximise their thrust per unit volume as well as avoid buckling instabilities, we predict that their bending rigidity must be about $3\times 10^{-9}~\mathrm{N\cdot \mu m^2}$. The verification of this prediction is left for future work.Comment: Accepted for publication in PRE on November 18 2014, 7 pages, 6 figure

The DVM and Professionalism: Editorial

As I approach my final year of Veterinary Medicine, I frequently ask myself, for what reason? Is the basis for my D.V.M. personal gain and position? Is it to attain a prestigious position in the world of professionalism? There are visions of a luxurious life - fine cars, spacious property and homes, active social lives and many important friends. Are these my primary goals

Determination of the Mutual Inductance of End Turns of Induction Motors

The object in making the following investigation was to facilitate the obtaining of a more accurate determination of the reactance of the end turns of rotating alternating current machinery. Such formulae as are available at present are, as far as the author knows, based on incorrect assumptions, or fail to consider the various factors present. The accuracy of the results obtained when using such formulae is very small. Often the calculated reactance will not be within 400% of the correct value. Because of this, it was felt that a more accurate analysis of this problem would be of value, chiefly to the designing engineer. In this report, the "end turns" of the machine windings are considered to be the part of the turns of the coils on the armature of the machine not lying in armature slots. These turns, the connecting conductors between the armature bars, lie against each other in a belt extending around the circumference of the armature. In nearly all motor coils, the end turns consist of a short section extending straight out from the armature slot, a much longer section bent nearly parallel with the core, an abruptly curved end section, and two lengths similar to the first two. It is obvious that the accurate determination of the inductance of such coils must take into account the peculiar shape of the coils and the effect of the coils upon each other. It is this second effect which is usually neglected in determinations of the reactance. Actually this mutual inductance is of greater importance than the self inductance of the coils.</p

The self-concept of children disfigured by burns and the effect of role-play on their self-concept

Bibliography: pages 200-211.This study aimed at investigating the role of physical-distinctiveness as a pertinent feature of self-concept, using the special case of children disfigured by burns. Within this group of children, the study also aimed to explore, by means of a comparative study, the possibility of improving the self-concept of burned children, through the use of selected components of the D.U.S.O. Guidance Programme. Lastly, the study aimed at gaining a clear picture of the burned child in terms of both social and psychological features. Twenty-seven subjects, in three matched groups (burn treatment group, burn control group and non-burn control group) took part in the study. The burn treatment group participated in the D.U.S.O. Programme which took place over a period of five consecutive days with five daily sessions of 90 minutes each. The burn control group took part in sessions similar to those of the burn treatment group, except that they participated in play and not the D.U.S.O. Programme. The non-burn control group was introduced as a baseline measure and did not take part in any sessions. It was hypothesized that the burn groups of children would show a significant increase in overall self-concept as a result of enrichment offered by the daily sessions. It was similarly hypothesized that, due to enrichment provided by the D.U.S.O. Programme, the burn treatment group would, when compared to the burn control group, show a significant increase in overall self-concept. It was further hypothesized that the burn treatment group would, when compared to the control groups, show a significant increase in social-self, parental-self, physical-self and school-self self-concept subscales while showing a significant decrease in aggression and body-image disturbance scores on the Draw-a-Person test, due to the greater understanding and acceptance of the self promoted by the D.U.S.O. Programme. Data obtained through the use of Laubscher's (1978) Self-Concept Questionnaire for Primary School Children (Afrikaans) and Machover's Draw-a-Person test failed to support the hypotheses. A broad trend for the burn treatment group to increase on social- and physical-self subscales of self-concept was, however, found. Quantitative data were combined and these, together with data from an Adaptation Questionnaire, based on the American Association on Mental Deficiency's "Adaptive Behaviour Scale" (1975), formed the basis for building-up a profile of the psychosocial adjustment of the burned child. Results were discussed with reference to the literature. The study's limitations were examined and future areas of research were suggested

The Decision to Pursue the Principalship: Perspectives of Certified Administrators in Upstate Central New York

This qualitative research study sought to uncover the attractants and deterrents of educational administrative positions in Upstate Central New York (CNY) public schools by exploring the perspectives of both practicing principals and those that are certified but not currently employed in an administrative position. The study posed three research questions. First, how do educators who are certified as administrators in Upstate Central New York describe experiences that have influenced them to pursue or not pursue the principalship? Second, what do certified administrators perceive as the attractants and deterrents to the principalship in Upstate Central New York and which of these are factors in their decision to apply for and accept principalships? Finally, how have the attractants and deterrents to the principalship changed in the recent years covered by this study? Participants in the study included certified educational administrators that are both practicing principals as well as those that have not yet assumed an administrative position. Purposeful and snowball sampling techniques were utilized to include participants from rural, urban, and suburban settings in CNY. Two separate cohorts, interviewed five years apart, provided insight into the changing landscape of the principalship. Findings addressing the research questions are based on five themes that emerged during the study: Accountability, Nature of the Job, Terms and Conditions of Employment, Climate, and Personal Factors. The longitudinal nature of this study revealed the emergence of the Annual Professional Performance Review (APPR) requirements as a recent major factor impacting the decision of certified administrators to seek, accept, and remain in the principalship in New York State. The conclusions of this study have potential significance to assist decision makers of CNY public schools to better understand and attract high quality candidates from the available candidate pool. Recommendations and implications are enumerated and proposed for educational constituent groups in New York State including Superintendents and Boards of Education, the New York State Education Department and State Government, Public and Private Universities with preparation programs in Educational Leadership, Professional Associations (SAANYS, NYSSBA, NYSCSS), and the Central New York School Study Council. School districts need to provide a rich professional fulfilling work environment to both attract and retain principals. As the principal is the key to promoting academic excellence, a supportive work environment that accentuates the attractants and minimizes the deterrents will facilitate the provision of a high quality, equitable education to all children throughout the diverse communities of CNY