Modelling Curriculum Choice at A-level: Why is Business Studies More Popular than Economics?

This paper uses A-level Information System (ALIS) data to quantify the determinants of the choice between Economics and Business Studies at A-level. These subjects are often perceived as close curriculum options and possible substitutes in the UK. Subject choice is modelled using an underlying latent variable approach. On the basis of a series of counterfactual exercises an overall average grade differential, a measure of their comparative difficulty, is estimated to be 1.3 (old) UCAS points, equivalent to approximately two-thirds of a letter grade, in favour of Business Studies. The estimating equation suggests that a unit increase in the grade differential increases the probability of selecting Business Studies over Economics by approximately 12 percentage points. There is evidence that females are less likely to choose Economics over Business Studies and the more able students, in terms of their average GCSE score and mathematical ability, are more likely to select Economics. There is also some evidence of parental background characteristics and ethnicity exerting significant effects on the choice between these two subjects.

Lower Bounds on U_{e3}

We give minimal values for the smallest lepton mixing parameter U_{e3}, applying 2-loop renormalization group equations in an effective theory approach. This is relevant in scenarios that predict an inverted neutrino mass spectrum with the smallest mass and U_{e3} being zero at tree level, a situation known to be preserved at 1-loop order. At 2-loop, U_{e3} is generated at a level of 10^{-12}-10^{-14}. Such small values are of interest in supernova physics. Corresponding limits for the normal mass ordering are several orders of magnitude larger. Our results show that U_{e3} can in general expected be to be non-zero.Comment: 5 pages, 2 figures. Matches published versio

South Africa’s new Cooperatives Act: A missed opportunity for small farmers and land reform beneficiaries

Agricultural cooperatives are often viewed as appropriate vehicles to facilitate vertical coordination with, or horizontal integration between, small farmers who would otherwise be excluded from value-adding opportunities and discerning markets. In South Africa, renewed interest in development-oriented cooperatives saw the introduction of a new Cooperatives Act in 2005, along with support measures dedicated to ‘emerging’ cooperatives. This paper contends that the architects of the new Act discounted important trends in international legislation that would have made development-oriented cooperatives more versatile and given their members better access to capital and expertise through equity partnerships with private agribusiness firms. It is concluded that the new Act should be amended to admit non-patron investors as members, and to allow for non-redeemable and hence appreciable and tradable shares. Such innovations are emerging internationally, usually with a cap on non-patron voting power.Agricultural cooperatives, small farmers, new institutional economics, strategic partnerships, land reform beneficiaries,

A NOTE ON NONLINEARITY BIAS AND DICHOTOMOUS CHOICE CVM: IMPLICATIONS FOR AGGREGATE BENEFITS ESTIMATION

It is a generally known statistical fact that the mean of a nonlinear function of a set of random variables is not equivalent to the function evaluated at the means of the variables. However, in dichotomous choice contingent valuation studies a common practice is to calculate an overall mean (or median) by integrating over offer space (numerically or analytically) an estimated logit or probit function in which sample mean values for the concomitant variables are used. We demonstrate this procedure to be incorrect and we statically test the procedure against the correct method for nonlinear models. Using data resulting in a well-behaved logit model, we reject the hypothesis of congruence between the two means. Such a finding should be considered in future single response dichotomous choice CVM studies, particularly when aggregation is of interest.Research Methods/ Statistical Methods,

A Targeted Therapeutic Rescues Botulinum Toxin-A Poisoned Neurons

Botulinum neurotoxin (BoNT), a Category A biothreat agent, is the most potent poison known to mankind. Currently no antidote is available to rescue poisoned synapses. BoNT acts specifically by blocking neurotransmission primarily at peripheral nerve-muscle junctions causing severe flaccid muscle paralysis, which is fatal if proper medical care is not provided. The neurotoxin acts by specifically entering the presynaptic nerve endings where it interferes with the biochemical machinery involved in the process of neurotransmitter release, i.e., neuroexocytosis. Most serotypes of BoNT are known to remain active for weeks to months after entering the nerves, but BoNT/A is the most potent and long lasting in causing muscle paralysis. An effective medical countermeasure strategy requires developing a drug that could rescue poisoned neuromuscular synapses, and would include its efficient delivery specifically to presynaptic nerve terminals. Here we report rescuing of botulinum poisoned nerve cells by Mastoparan-7 (Mas-7), a peptide constituent of bee venom, that was delivered through a drug delivery vehicle (DDV) constructed from the non-toxic fragment of botulinum neurotoxin itself. We found that Mas-7 that was delivered into BoNT/A intoxicated cultured mouse spinal cord cells restored over 40% of stimulated neurotransmitter release. The rescue of the cell poisoning did not occur from inhibition of the endopeptidase activity of BoNT/A against its well known substrate, SNAP-25 that is mechanistically involved in the exocytosis process. Rather, Mas-7 induced a physiological host response apparently unrelated to SNAP-25, but linked to the phospholipase signal transduction pathway. In addition to providing the first effective antidote against botulism, our results open new avenues to study the mechanism of exocytosis, and also to examine an alternative cellular mechanism of botulinum neurotoxin action. An effective BoNT-based DDV can also be utilized for drug delivery against many neuronal and neuromuscular disorders

X-Ray Eclipse Timing in the LMXB EXO0748-676

Orbital period changes are an important diagnostic for understanding low mass X-ray binary (LMXB) accretion-induced angular momentum exchange and overall system evolution. We present our most recent results for the eclipse timing of the LMXB EXO0748-676. Since its discovery in 1985 it has apparently undergone three distinct orbital period "epochs", each characterized by a different orbital period than the previous epoch. We outline the orbital period behavior for EXO0748-676 over the past 18 years and discuss the implications of this behavior in light of current theoretical ideas for LMXB evolution.Comment: 4 Pages, 3 Figures, Submitted to the X-Ray Timing 2003: Rossi and Beyond conference, November 200

Short-term memory trace mediated by termination kinetics of olfactory receptor.

Odorants activate receptors in the peripheral olfactory neurons, which sends information to higher brain centers where behavioral valence is determined. Movement and airflow continuously change what odor plumes an animal encounters and little is known about the effect one plume has on the detection of another. Using the simple Drosophila melanogaster larval model to study this relationship we identify an unexpected phenomenon: response to an attractant can be selectively blocked by previous exposure to some odorants that activates the same receptor. At a mechanistic level, we find that exposure to this type of odorant causes prolonged tonic responses from a receptor (Or42b), which can block subsequent detection of a strong activator of that same receptor. We identify naturally occurring odorants with prolonged tonic responses for other odorant receptors (Ors) as well, suggesting that termination-kinetics is a factor for olfactory coding mechanisms. This mechanism has implications for odor-coding in any system and for designing applications to modify odor-driven behaviors