Finite element simulation of thunderstorm electrodynamics in the proximity of the storm

Observations of electric fields, Maxwell current density, and air conductivity over thunderstorms were presented. The measurements were obtained using electric field mils and conductivity probes installed on a U2 aircraft as the aircraft passed approximately directly over an active thunderstorm at an altitude of 18 to 20 km. Accurate electrical observations of this type are rare and provide important information to those involved in numerically modeling a thunderstorm. A preliminary set of computer simulations based on this data were conducted and are described. The simulations show good agreement with measurements and are used to infer the thundercloud's charging current and amount of charge exchanged per flash

Worms: Education and Health Externalities in Kenya

Intestinal helminths - including hookworm, roundworm, schistosomiasis, and whipworm - infect more than one-quarter of the world's population. A randomized evaluation of a project in Kenya suggests that school-based mass treatment with deworming drugs reduced school absenteeism in treatment schools by one quarter; gains are especially large among the youngest children. Deworming is found to be cheaper than alternative ways of boosting school participation. By reducing disease transmission, deworming creates substantial externality health and school participation benefits among untreated children in the treatment schools and among children in neighboring schools. These externalities are large enough to justify fully subsidizing treatment. We do not find evidence that deworming improves academic test scores. Existing experimental studies, in which treatment is randomized among individuals in the same school, find small and insignificant deworming treatment effects on education; however, these studies underestimate true treatment effects if deworming creates positive externalities for the control group and reduces treatment group attrition.

Movement of Adult Colorado Potato Beetles, \u3ci\u3eLeptinotarsa Decemlineata\u3c/i\u3e (Coleoptera: Chrysomelidae), in Response to Isolated Potato Plots

Mark recapture techniques were used to determine Colorado potato beetle movement in circular arenas with isolated plots of potatoes at each ordinal direction. Post-diapause beetles aggregated on one or a few of the plants in one of the plots for each release, but not on the same plants in different releases. Differences in plant attractiveness were therefore not likely responsible for the aggregatory behavior. Aggregations were probably a result of either coordinated movement from the release site to the plants or an aggregatory signal with a range of at least 15 m. Summer adults did not aggregate on plants. Correlations of summer beetle recapture distributions to wind direction showed that anemotactic behavior could not account for the major portion of variation in beetle orientation to the potato plots. Some positive attraction to the plots was indicated because more beetles were recaptured at the plots than would be expected from random motion. The number of beetles recaptured at plots covered by cheesecloth was not significantly different from recaptures on uncovered plots, indicating little reliance on visual cues specific to potatoes for location of the plants

The Illusion of Sustainability

The history of foreign development assistance is one of movement away from addressing immediate needs and toward focusing on the underlying causes of poverty. A recent manifestation is the move towards sustainability,' which stresses community mobilization, education, and cost-recovery. This stands in contrast to the traditional economic analysis of development projects, with its focus on providing public goods and correcting externalities. We examine evidence from randomized evaluations on strategies for combating intestinal worms, which affect one in four people worldwide. Providing medicine to treat worms was extremely cost effective, although medicine must be provided twice per year indefinitely to keep children worm-free. An effort to promote sustainability by educating Kenyan schoolchildren on worm prevention was ineffective, and a mobilization' intervention from psychology failed to boost deworming drug take-up. Take-up was highly sensitive to drug cost: a small increase in cost led to an 80 percent reduction in take-up (relative to free treatment). The results suggest that, in the context we examine, the pursuit of sustainability may be an illusion, and that in the short-run, at least, external subsidies will remain necessary.

On bound states of multiple t-quarks due to Higgs exchange

Froggatt, Nielsen et al suggested that the Higgs boson exchange between top quarks produces enough attraction to generate their multiple bound states. Furthermore they claimed that the system of 6 top and 6 anti-top quarks is bound so strongly that the binding energy nearly compensates the masses of t-quarks, making it very light. We calculated the energy of such states more accurately, variationally and by self-consistent mean field approximation, and found that these state are weakly bound for massless Higgs boson and unbound with the account for its mass.Comment: 3 page

The Shane Wirtanen counts: Observability of the galaxy correlation function

For an explicit test of the ability to recover the galaxy two-point correlation function from the Lick catalog of Shane and Wirtanen, we have applied the reduction and analysis methods of Seidner et al. and Groth and Peebles to model galaxy distributions that have known plate and field "errors" and that are high-fidelity simulations of the Lick sample. The model galaxy space distribution is constructed with the Soneira-Peebles prescription, which generates model distributions which have two-, three-, and four-point correlation functions in good agreement with the observed correlation functions. The space distribution is projected onto the sky with and without plate "errors." The Seidner et al. analysis recovers the plate factors in the former case with an error of 6.3%, as originally estimated. The two-point correlation function estimated from the "corrected" model catalog reproduces the built-in correlation function including the break from the power law. This is also true if the angular scale of the break is increased or decreased by a factor of 1.76 from the observed value. We also compare a map of the corrected counts with a map of the counts projected without plate errors and find that the corrected map is a good visual representation of the galaxy distribution. Finally, we construct a simulation which includes systematic variations in plate sensitivity with observer and time-so called "plate shape gradients." Once again, the correlation function of the model catalog reproduces the built in correlation function