Crop raiding patterns of solitary and social groups of red-tailed monkeys on cocoa pods in Uganda

Crop damage by wildlife is a very prevalent form of human-wildlife conflict adjacent to protected areas, and great economic losses from crop raiding impede efforts to protect wildlife. Management plans are needed to decrease damage by raiding wildlife, yet conservation biologists typically lack the basic information needed for informed conservation strategies. Red-tailed monkeys (Cercopithecus ascanius) raid a variety of crops adjacent to protected forests in East Africa; however, the role of group structure on crop raiding has not been explored. Here, crop raiding patterns of solitary males and social groups were investigated during 10 months in a plantation of mature cocoa in Uganda. Monkeys gained access to the plantation via trees planted as wind breaks and shade trees, and the sighting frequency of groups was negatively related to the distance from the forest edge. In contrast, solitary males were sighted more frequently far from the forest edge and caused proportionately greater damage than members raiding in a social group. These results highlight that for social animals, crop raiding behavior can vary among types of social groupings; appropriate strategies to cope with raiding must therefore respond to this variation. Deborah Baranga, G. Isabirye Basuta, Julie A. Teichroeb, and Colin A. Chapman

Spin-axis relaxation in spin-exchange collisions of alkali atoms

We present calculations of spin-relaxation rates of alkali-metal atoms due to the spin-axis interaction acting in binary collisions between the atoms. We show that for the high-temperature conditions of interest here, the spin relaxation rates calculated with classical-path trajectories are nearly the same as those calculated with the distorted-wave Born approximation. We compare these calculations to recent experiments that used magnetic decoupling to isolate spin relaxation due to binary collisions from that due to the formation of triplet van-der-Waals molecules. The values of the spin-axis coupling coefficients deduced from measurements of binary collision rates are consistent with those deduced from molecular decoupling experiments. All the experimental data is consistent with a simple and physically plausible scaling law for the spin-axis coupling coefficients.Comment: text+1 figur

Spin Relaxation Resonances Due to the Spin-Axis Interaction in Dense Rubidium and Cesium Vapor

Resonances in the magnetic decoupling curves for the spin relaxation of dense alkali-metal vapors prove that much of the relaxation is due to the spin-axis interaction in triplet dimers. Initial estimates of the spin-axis coupling coefficients for the dimers are 290 MHz for Rb; 2500 MHz for Cs.Comment: submitted to Physical Review Letters, text + 3 figure

Ion beam propagation in a transverse magnetic field and in a magnetized plasma

Propagation of a charge-neutralized ion beam, in a transverse magnetic field (Bz <400 G) and in a magnetized plasma, has been studied. Measurements indicate that the beam propagation mechanism is due to the E×B drift in the region of high β (1<β<400), where β is the ratio of beam kinetic energy to transverse magnetic field energy. Diamagnetic measurements, both internal and external to the propagating beam, confirm the fast diffusion of Bz into the beam on a time scale much shorter than the beam rise time of 10-7 s. When the beam is injected into a magnetized plasma the electric field is shorted to a degree that increases with increasing background plasma density. When the plasma density reaches 1013/cm3 (∼200×the beam density) complete shorting occurs and the beam is deflected by the transverse magnetic field

Microwave radiation by a relativistic electron beam propagation through low‐pressure air

Intense relativistic electron beams fired into air at varying pressures display a wide range of microwave signatures. These experiments held beam current, energy, and pulse length constant while varying gas pressure. Our observing window is 10 to 40 GHz. At low pressures ( less than 10m Torr) exponential spectra result, consistent with beam reflexing or virtual cathode oscillations. Above 20 m Torr the spectrum flattens and suggests collective emission at the beam-generated plasma frequencies. Power falls linearly with pressure above 20 m Torr, until electron-Neutral collisions damp the emission at a few Torr. However, weak 10 GHz emission appears at full atmospheric pressure

MICROWAVE-RADIATION BY A RELATIVISTIC ELECTRON-BEAM PROPAGATION THROUGH LOW-PRESSURE AIR

Intense relativistic electron beams fired into air at varying pressures display a wide range of microwave signatures. These experiments held beam current, energy, and pulse length constant while varying gas pressure. Our observing window is 10 to 40 GHz. At low pressures ( less than 10m Torr) exponential spectra result, consistent with beam reflexing or virtual cathode oscillations. Above 20 m Torr the spectrum flattens and suggests collective emission at the beam-generated plasma frequencies. Power falls linearly with pressure above 20 m Torr, until electron-Neutral collisions damp the emission at a few Torr. However, weak 10 GHz emission appears at full atmospheric pressure