M-PESA: Finding new ways to serve the unbanked in Kenya

Over the past three years, payment strategies for emerging markets have been revolutionized by the advent of a simple cell-phone-based payment service in Kenya called M-PESA (“M” for “mobile” and “pesa” for “money”). From a small-scale pilot program in 2006, M-PESA has become an outstanding success in Kenya; customer response has been unprecedented. Currently, more than 9 million Kenyans use M-PESA to perform tens of millions of transactions every month throughout the country. Although this success has led to new opportunities, it has also brought about many unforeseen challenges.M-PESA, Mobile Phone, rural areas, rural banking, safe money transfers, small-scale pilot programs,

Holonomy and Projective Equivalence in 4-Dimensional Lorentz Manifolds

A study is made of 4-dimensional Lorentz manifolds which are projectively related, that is, whose Levi-Civita connections give rise to the same (unparameterised) geodesics. A brief review of some relevant recent work is provided and a list of new results connecting projective relatedness and the holonomy type of the Lorentz manifold in question is given. This necessitates a review of the possible holonomy groups for such manifolds which, in turn, requires a certain convenient classification of the associated curvature tensors. These reviews are provided.Comment: Comments: 23 pages, LaTeX; typos corrected, page 9 last line corrected to $g'=e^{2\chi}a^{-1}

Studies on the photo-oxidation of chlorophyll

Examination has bean made of the ohotooxidation, in visible light, of chlorophyll preparations, deposited on various solids, by means of the direct measurement of oxygen pressure decrease.Rates of oxidation were very low on glass, zinc oxide, aluminium oxide, ferric oxide, and on talc, but were some five to ten times more rapid on thallous bromide and thallous iodide. The maximum quantum efficiency on glass in light of wave length 4358 A.U. was of the order 10⁻², increasing slightly with decreasing film thickness.Chromatographic and solvent partition separation methods applied to two chlorophyll preparations enabled two main fractions to be examin¬ ed, a yellow carotene fraction and the green chloro¬ phyll fraction. Cn thallous bromide, the oxygen to carotene and the oxygen to chlorophyll molar ratios in oxidation were unity. The chlorophyll fraction of a second sample showed an apparent oxygen to chlorophyll molar ratio of approximately two. Oxidations were partly reversible by simple pressure reduction. For one chlorophyll preparation, a limit of oxygen pressure of approximately 0.1mm. was established, below which no oxidation occurred.A possible mechanism has been discussed in relation to the experimental results and to the general nature of such preparations