Chaotic and regular motion around generalized Kalnajs discs

The motion of test particles in the gravitational fields generated by the first four members of the infinite family of generalized Kalnajs discs, is studied. In first instance, we analyze the stability of circular orbits under radial and vertical perturbations and describe the behavior of general equatorial orbits and so we find that radial stability and vertical instability dominate such disc models. Then we study bounded axially symmetric orbits by using the Poincare surfaces of section and Lyapunov characteristic numbers and find chaos in the case of disc-crossing orbits and completely regular motion in other cases

Electric Vehicles

This chapter regards the current state of electric vehicles in society today: the pros and cons, areas that need to improve, etc. The chapter starts by discussing some of the unethical practices that go into creating commodities of electric vehicles. From there, we explore the short, yet rapidly changing history of electric vehicles. Topics explored throughout its history include early inefficiencies, the introduction of hybrids that led to major improvements, and the increase in availability. The chapter then explores markets and commodities of electric vehicles, which explores the supply and demand side of this technology. We will show how growing demand has lead to improved government action, and how production methods must be improved for a sustainable future of electric vehicles. Finally, we test the ethics of electric vehicles, challenging the notion of nothing but the most ethical environmental standards. We will show how ways of metal mining and electricity generation actually do more bad than good for our environment. By reading this chapter, you will become more knowledgeable of how impactful electric vehicles are, and also you will get a grasp on whether or not you want to support this practice.Angela Person, Ph.D.N

Employment Testing and Incentives to Learn

Employment tests predict job performance because they measure or are correlated with a large set of malleable developed abilities which are causally related to productivity. Our economy currently under-rewards the achievements that are measured by these tests. Consequently, economic incentives to study hard in high school are minimal and this absence of incentives has contributed to the low levels of achievement in math and science. The paper concludes with a discussion of ways in which employment tests can strengthen incentives to learn

Mixed methods evaluation of a primary eye care training programme for primary health workers in Morogoro Tanzania.

BACKGROUND: There are 285 million people with visual impairment (VI) worldwide including 39 million who are blind; 15 % of those with VI live in Africa, and around 80 % of VI is preventable or treatable with the right equipment, information and skills. The scarcity of human resources for eye health, particularly in Sub-Saharan Africa, is a key challenge towards achieving this goal. Therefore training primary health workers (PHW) in providing eye-care services has been seen by some authors as a way to improve access to eye-care services in remote communities. However, the package of interventions which could be effectively delivered for eye-care at the primary-care level or the set of skills and competencies that PHWs need has not yet been delineated. The aim of the study was to evaluate the effectiveness of a four day training programme of PHWs in primary eye-care conducted in Morogoro, Tanzania in 2010/2011. METHODS: A mixed methods study using pre- and immediate post-training knowledge assessment of 60 trainees, and in-depth face to face interviews with 20 PHWs and 8 service managers 2 to 3 years after the training. RESULTS: Pre-and immediate post-training assessments indicated improvement in health worker knowledge about eye-care in the short term. Qualitative investigations 2 to 3 years after the training showed that although staff could make the correct management decisions when presented with eye-health problems, they often could not make a correct diagnosis. PHWs and managers reported satisfaction with the content of the training but some of the less well qualified staff found it overwhelming. Theoretical teaching was appreciated by most participants but almost all suggested increasing the time spent on acquiring skills. The training manual was accepted by many and some improvements were recommended. All interviewed PHWs were keen to improve their skills and knowledge. Acquired skills and knowledge were used for identification, referral of patients and for eye-health promotion. CONCLUSION: The training program in Morogoro was considered by PHWs as broadly successful and satisfying in terms of content, methods and duration of training. However, any future programme needs to be considered within the context of strengthening wider health systems

Comment Regarding the Functional Form of the Schmidt Law

Star formation rates on the galactic scale are described phenomenologically by two distinct relationships, as emphasized recently by Elmegreen (2002). The first of these is the Schmidt law, which is a power-law relation between the star formation rate and the column density. The other relationship is that there is a cutoff in the gas density below which star formation shuts off. The purpose of this paper is to argue that 1) these two relationships can be accommodated by a single functional form of the Schmidt law, and 2) this functional form is motivated by the hypothesis that star formation is a critical phenomenon, and that as a corollary, 3) the existence of a sharp cutoff may thus be an emergent property of galaxies, as was argued by Seiden (1983), as opposed to the classical view that this cutoff is due to an instability criterion.Comment: 14 pages, 3 figures, in press, New Astronomy. Figs provided in original (png) format as well as ps format for ps/pdf generatio

Discovery of New Milky Way Star Cluster Candidates in the 2MASS Point Source Catalog II. Physical Properties of the Star Cluster CC01

Three new obscured Milky Way clusters were detected as surface density peaks in the 2MASS point source catalog during our on-going search for hidden globular clusters and massive Arches-like star clusters. One more cluster was discovered serendipitously during a visual inspection of the candidates. The first deep J, H, and Ks imaging of the cluster [IBP2002] CC01 is presented. We estimated a cluster age of ~1-3 Myr, distance modulus of (m-M)0=12.56+-0.08 mag (D=3.5 Kpc), and extinction of AV~7.7 mag. We also derived the initial mass function slope for the cluster: Gamma=-2.23+-0.16. The integration over the initial mass function yielded a total cluster mass M_{total}<=1800+-200Msol. CC01 appears to be a regular, not very massive star cluster, whose formation has probably been induced by the shock front from the nearby HII region Sh2-228.Comment: 8 pages, 9 figures, accepted in A&

Integration of Eye Health into Primary Care Services in Tanzania: A Qualitative Investigation of Experiences in Two Districts.

Background: Visual impairment is a public health problem in sub-Saharan Africa, affecting nearly 5% of the population. Efforts to combat avoidable causes have been hampered by weak health systems and little evidence exists to suggest what interventions may be effective to improve the situation. Despite this, there are calls to promote some specific interventions, one of which being the closer integration of eye health services into health systems, often focusing on training primary health workers to deliver basic eye health services. This study seeks to understand how eye health services are delivered by primary health workers who have received training and what constraints remain to effective service provision. Methods: This was a qualitative investigation into the experiences of 20 primary health workers trained in primary eye care and eight key informants working within specialist eye health services or regional and district health management positions in two districts in Tanzania. Results: Despite feeling confident in their own eye care skills, most primary health workers felt constrained in the services they could provide to their communities by insufficient resources needed for diagnosis and treatment, and by lack of systematic supportive supervision to their work. Specialist ophthalmic staff were aware of this issue, although for the most part they felt it was not within their capacity to remedy and that it fell within the remit of general health managers. Many participants discussed the low support to eye health from the national government, evidenced through the lack of dedicated funding to the area and traditional reliance on outside funds including international charities. Conclusions: Although training of primary health workers is useful, it is recognised that is not sufficient to address the burden of eye health disease present in rural communities in Tanzania. It is likely that broader engagement with the general health system, and most likely with the private sector, will be necessary to improve the coverage of eye health care to remote and poor communities such as those in Morogoro. Further investment is needed to develop innovative approaches to delivering eye health services, including preventative, curative and rehabilitative services

Schwann cell mitochondrial metabolism supports long-term axonal survival and peripheral nerve function

Mitochondrial dysfunction is a common cause of peripheral neuropathies. While the role of neuron and axonal mitochondria in peripheral nerve disease is well appreciated, whether Schwann cell (SC) mitochondrial deficits contribute to peripheral neuropathies is unclear. Here we examine how SC mitochondrial dysfunction affects axonal survival and contributes to the decline of peripheral nerve function by generating mice with SC-specific mitochondrial deficits. These mice (Tfam-SCKOs) were produced through the tissue-specific deletion of the mitochondrial transcription factor A gene (Tfam), which is essential for mitochondrial DNA (mtDNA) transcription and maintenance. Tfam-SCKOs were viable but, as they aged, they developed a progressive peripheral neuropathy characterized by nerve conduction abnormalities as well as extensive muscle denervation. Morphological examination of Tfam-SCKO nerves revealed early preferential loss of small unmyelinated fibers followed by prominent demyelination and degeneration of larger-caliber axons. Tfam-SCKOs displayed sensory and motor deficits consistent with this pathology. Remarkably, the severe mtDNA depletion and respiratory chain abnormalities in Tfam-SCKO mice did not affect SC proliferation or survival. Mitochondrial function in SCs is therefore essential for maintenance of axonal survival and normal peripheral nerve function, suggesting that SC mitochondrial dysfunction contributes to human peripheral neuropathies