Space charge in drift chambers operated with the Xe,CO2(15%) mixture

Using prototype modules of the ALICE Transition Radiation Detector we investigate space charge effects and the dependence of the pion rejection performance on the incident angle of the ionizing particle. The average pulse height distributions in the drift chambers operated with the Xe,CO2(15%) mixture provide quantitative information on the gas gain reduction due to space charge accumulating during the drift of the primary ionization. Our results demonstrate that the pion rejection performance of a TRD is better for tracks which are not at normal incidence to the anode wires. We present detailed simulations of detector signals, which reproduce the measurements and lend strong support to our interpretation of the measurements in terms of space charge effects.Comment: 18 pages, 10 figures, accepted for publication in Nucl.Instrum.Meth. A. Data files available at http://www-alice.gsi.de/tr

Changes in wild meat hunting and use by rural communities during the COVID‐19 socio‐economic shock

There is limited quantitative evidence of the effects of socio‐economic shocks on biological resource use. Focusing on wild meat hunting, a substantial livelihood and food source in tropical regions, we evaluated the impacts of the shock from Nigeria's coronavirus disease (COVID‐19) lockdown on species exploitation around a global biodiversity hotspot. Using a 3‐year quantitative dataset collected during and after the lockdown (covering 1008 hunter‐months) and matching by time of year, we found that successful hunting trip rates were more frequent during the lockdown, with a corresponding increase in the monthly number, mass, and value of animals caught. Moreover, hunters consumed a larger proportion of wild meat and sold less during lockdown, compared to non‐lockdown periods. These results suggest that local communities relied on wild meat to supplement reduced food and income during the lockdown, buffering the COVID‐19's socio‐economic shock. Our findings also indicate that wild species may be especially vulnerable to increased hunting pressure during socio‐economic shocks

Predictors of frequency and success of wild meat hunting trips and carcass prices in an African biodiversity hotspot

Hunting wild animals for food and income, which is pervasive across tropical regions, drives biodiversity loss. Interventions to promote sustainable wild meat harvesting require information on hunter behavior. Here we monitored the hunting activities of 33 hunters in SE Nigeria over three years (1,106 hunter-months) to identify correlates of (a) the probability of initiating a hunting trip on any given day; (b) trip success – whether an animal was caught, and if so, how many; and (c) carcass price. We found a higher probability of initiating a trip during periods with bright moon phases and in peak agriculture season. Hunters were more likely to catch at least one animal when there was less rainfall and on shorter hunting trips. However, among successful trips, the number of animals caught increased with trip duration. Taken together, these results suggest hunters set themselves a minimum target of not returning empty-handed rather than optimally adjusting their hunting effort. Lastly, the carcass price per kilogram of a species’ meat increased with its palatability but decreased with mass, with the fall in price observed to be greater for rarely caught, smaller-bodied animals than more frequently caught animals. Our results provide deeper insights into the behavioral plasticity of wild meat hunters