A horizontally polarizing liquid trap enhances the tabanid-capturing efficiency of the classic canopy trap

Host-seeking female tabanid flies, that need mammalian blood for the development of their eggs, can be captured by the classic canopy trap with an elevated shiny black sphere as a luring visual target. The design of more efficient tabanid traps is important for stock-breeders to control tabanids, since these blood-sucking insects can cause severe problems for livestock, especially for horse- and cattle-keepers: reduced meat/milk production in cattle farms, horses cannot be ridden, decreased quality of hides due to biting scars. We show here that male and female tabanids can be caught by a novel, weather-proof liquid-filled black tray laid on the ground, because the strongly and horizontally polarized light reflected from the black liquid surface attracts water-seeking polarotactic tabanids. We performed field experiments to reveal the ideal elevation of the liquid trap and to compare the tabanid-capturing efficiency of three different traps: (1) the classic canopy trap, (2) the new polarization liquid trap, and (3) the combination of the two traps. In field tests, we showed that the combined trap captures 2.4–8.2 times more tabanids than the canopy trap alone. The reason for the larger efficiency of the combined trap is that it captures simultaneously the host-seeking female and the water-seeking male and female tabanids. We suggest supplementing the traditional canopy trap with the new liquid trap in order to enhance the tabanid-capturing efficiency.

PROTON INELASTIC DIFFRACTION BY A BLACK NUCLEUS AND THE SIZE OF EXCITED NUCLEI

We systematically derive a length scale characterizing the size of a low-lying, β stable nucleus from empirical data for the diffraction peak angle in the proton inelastic differential cross-section of incident energy of ~ 1 GeV. In doing so, we assume that the target nucleus in the ground state is a completely absorptive "black" sphere of radius a. The cross-section πa2, where a is determined in such a way as to reproduce the empirical proton diffraction peak angle in the elastic channel, is known to agree with empirical total reaction cross-sections for incident protons to within error bars. By comparing the inelastic diffraction patterns obtained in the Fraunhofer approximation with the experimental ones, one can likewise derive the black sphere radius al for the excited state with spin l. We find that for 12 C , 58, 60, 62, 64 Ni , and 208 Pb , the value of al obtained from the inelastic channel is generally larger than the value of a from the elastic channel and tends to increase with the excitation energy. This increase is remarkable for the Hoyle state. Finally, we discuss the relation between al and the size of excited nuclei.

The Sweetshops of Kolkata

Obsession with dessert is widely shared by the residents of Kolkata. Life's passages and religious rituals are all celebrated with sugary creations. Bengali desserts are typically made with some sort of milk product. Among these are mishti doi a custard-like dessert made by adding yogurt cultures to sweetened evaporated milk. However, Bengal is best known for desserts based on chhana. This is a fresh cheese with a consistency similar to ricotta. Some chhana is made into fritters, which include pantua, a doughnut-brown ball about the size of a lime, and kalojam, a nearly jet black sphere of dough. Both of these are soaked in syrup. Rossogolla is made from a similar dough but is boiled rather than fried. When soaked in a milk-based syrup, it is called rossomalai. In a simpler preparation, the fresh cheese is cooked down with sugar and formed into many kinds of sweets called sandesh. One of the city's best know sandesh shops is Girish Chandra Dey & Nakur Chandra Nandy, or Nakur, in the old Shyambazar district. At Nakur they begin with raw milk, process it into cheese, and then cook, form, and flavor it into many types of sandesh of often unorthodox flavors. This artisanal approach cannot be followed by smaller neighborhood confectioners, called moiras in Bengali. They often use ready-made chhana for their confections. Trying to keep up with the times, new confectioners have tried to expand their operations and offer new products some of which are artificially sweetened.