Welded repairs of punctured thin-walled aluminum pressure vessels

Punctures in thin-walled aluminum pressure vessels are repaired by plugging the hole with an interference-fit disc and welding the unit. The repaired vessels withstood test pressures in excess of vessel ultimate design values for 2-, 4-, and 6-inch holes in 0.202-inch-thick aluminum alloy parent material

Minority Adolescents at Risk for Obesity: Health Behaviors and Perceptions

The purpose of this study was to examine behaviors related to nutrition and physical activity of inner-city minority adolescents, and their perception of normal weight and overweight. The research study used a descriptive, non-experimental design which had a convenience sample of thirty-seven 8th grade minority adolescents who attended a chartered urban K-8 grade school in Northern California. There were no statistically significant differences in the results, however, over 50% of the students reported not eating the recommended daily servings of fruits and vegetables. Another 68% reported participating more than 30 minutes in exercising or playing sports during physical education class. Although 42% of the students reported being the right weight, they wanted to lose weight. This demonstrates a need for healthy nutritional behavior and physical activity amongst this population. School nurses can play an important role in identifying at risk students for obesity and provide education in nutrition, structured physical activities, and obesity prevention strategies

'Requisite irony' and the knowledge based economy: a critical discourse analysis of the drafting of education policy in the european union

This chapter makes a case for combining the critical analysis of discourse with an embrace of ‘self-reflexive irony’ (Jessop, 2002, 2004a) in the investigation of the articulations between the Knowledge Based Economy (KBE) and education policy in the European Union (EU). Irony is embraced as a topic within the study of EU governance of education policy in so far as it contributes to an analysis of the activities of supranational and national actors within complex multi-scalar political structures. In addition, the implications of self-reflexive irony are considered so as to suggest a series of clarifications for the process of analysing policy texts within a Critical Discourse Analysis (CDA) framework (Fairclough,1989,1996,1999). In essence, the chapter does two things. It interrogates the contradictory strategies and sources of conflict in the production of EU scale education policy texts and questions both the significance and the stability of the articulation of education reform with KBE discourses. At the same time, the chapter argues that the production of such texts contingently but incrementally contributes to the production of a relatively stable governance framework for EU scale education policy and that it is to the significance of this that a critical discourse analysis leads

Prospects for Detection of Synchrotron Emission from Secondary Electrons and Positrons in Starless Cores: Application to G0.216+0.016

We investigate the diffusion of cosmic rays into molecular cloud complexes. Using the cosmic-ray diffusion formalism of Protheroe, et al. (2008), we examine how cosmic rays diffuse into clouds exhibiting different density structures, including a smoothed step-function, as well as Gaussian and inverse-$r$ density distributions, which are well known to trace the structure of star-forming regions. These density distributions were modelled as an approximation to the Galactic centre cloud G0.216+0.016, a recently-discovered massive dust clump that exhibits limited signs of massive star formation and thus may be the best region in the Galaxy to observe synchrotron emission from secondary electrons and positrons. Examination of the resulting synchrotron emission, produced by the interaction of cosmic ray protons interacting with ambient molecular matter producing secondary electrons and positrons reveals that, due to projection effects, limb-brightened morphology results in all cases. However, we find that the Gaussian and inverse-$r$ density distributions show much broader flux density distributions than step-function distributions. Significantly, some of the compact (compared to the $2.2''$ resolution, 5.3 GHz JVLA observations) sources show non-thermal emission, which may potentially be explained by the density structure and the lack of diffusion of cosmic rays into the cloud. We find that we can match the 5.3 and 20 GHz flux densities of the non-thermal source JVLA~1 and 6 from Rodr\'{\i}guez & Zapata (2014) with a local cosmic ray flux density, a diffusion coefficient suppression factor of $\chi=0.1-0.01$ for a coefficient of $3\times10^{27}$ cm$^2$ s$^{-1}$, and a magnetic field strength of 470 $\mu$G.Comment: 4 pages, 2 figures, accepted for publication in the Astrophysical Journal Letter

Pulsar state switching, timing noise and free precession

Recent radio pulsar observations have shown that a number of pulsars display interesting long term periodicities in their spin-down rates. At least some of these pulsars also undergo sharp changes in pulse profile. This has been convincingly attributed to the stars abruptly switching between two different magnetospheric states. The sharpness of these transitions has been taken as evidence against free precession as the mechanism behind the long term variations. We argue that such a conclusion is premature. By performing a simple best-fit analysis to the data, we show that the relationship between the observed spin and modulation periods is of approximately the correct form to be accounted for by the free precession of a population of neutron stars with strained crusts, the level of strain being similar in all of the stars, and consistent with the star retaining a memory of a former faster rotation rate. We also provide an argument as to why abrupt magnetospheric changes can occur in precessing stars, and how such changes would serve to magnify the effect of precession in the timing data, making the observation of the precession more likely in those stars where such switching occurs. We describe how future observations could further test the precession hypothesis advanced here.Comment: Additional reference inserted; to appear in MNRA

Parameter choices and ranges for continuous gravitational wave searches for steadily spinning neutron stars

We consider the issue of selecting parameters and their associated ranges for carrying out searches for continuous gravitational waves from steadily rotating neutron stars. We consider three different cases (i) the "classic" case of a star spinning about a principal axis; (ii) a biaxial star, not spinning about a principal axis; (iii) a triaxial star spinning steady, but not about a principal axis (as described in Jones, MNRAS vol 402, 2503 (2010)). The first of these emits only at one frequency; the other two at a pair of harmonically related frequencies. We show that in all three cases, when written in terms of the original "source parameters", there exist a number of discrete degeneracies, with different parameter values giving rise to the same gravitational wave signal. We show how these can be removed by suitably restricting the source parameter ranges. In the case of the model as written down by Jones, there is also a continuous degeneracy. We show how to remove this through a suitable rewriting in terms of "waveform parameters", chosen so as to make the specialisations to the other stellar models particularly simple. We briefly consider the (non-trivial) relation between the assignment of prior probabilities on one set of parameters verses the other. The results of this paper will be of use when designing strategies for carrying out searches for such multi-harmonic gravitational wave signals, and when performing parameter estimation in the event of a detection.Comment: Updated to match version accepted by MNRAS: One new equation (equation 82)); typo (sign-error) corrected in equation (88); one more paragraph inserted into Summary and Discussion sectio