Evaluation of a warfarin bait for controlling invasive wild pigs (Sus scrofa)

BACKGROUND

Wild pigs (Sus scrofa) cause widespread environmental and economic damage, and as a result are subjected to extensive control. Current management strategies have proven insufficient, and there is growing interest in use of toxicants to control invasive populations of this species. In 2017 a low-dose warfarin bait was federally approved for use in controlling wild pigs in the United States. However, no states have allowed use of this bait due to unanswered questions regarding welfare concerns, field efficacy, and non-target impacts.

RESULTS

All captive wild pigs fed 0.005% warfarin baits in no choice feeding trials succumbed in an average of 8 days from exposure. Behavioral symptoms of warfarin exposure included vomiting, external bleeding, abnormal breathing, incoordination, and limping. Postmortem examinations revealed hemorrhaging in organs and muscles, particularly the legs, gastrointestinal tract, and abdomen. Warfarin residues in tissues averaged 1.0 mg kg^-1 for muscle, 3.9 mg kg^-1 for liver, and 2.8 mg kg^-1 for small intestines. Field testing revealed wild pigs required extensive training to access bait within pig-specific bait stations, and once acclimated, exhibited reluctance to consume toxic baits, resulting in no mortalities across two separate field deployments of toxic bait.

CONCLUSION

Our results suggest wild pigs are susceptible to low-dose warfarin, and warfarin residues in pig tissues postmortem are generally low. However, although warfarin-based baits are currently approved for use by the US Environmental Protection Agency, further improvements to pig-specific bait delivery systems and bait palatability are needed, as well as additional research to quantify efficacy, cost, and non-target impacts prior to widespread implementation. © 2021 Society of Chemical Industry. This article has been contributed to by US Government employees and their work is in the public domain in the USA.

Direct measurement of TEM lamella thickness in FIB-SEM

Transmission electron microscope (TEM) specimen preparation by focused ion beam (FIB) milling requires delicate polishing of a thin window of material during the final stages of the procedure. Over or underpolishing is common and requires extra microscope resources to correct. Despite some methods for lamella thickness measurement being available, the majority of users judge the final polishing step subjectively from scanning electron microscope (SEM) images acquired between milling steps. Here we demonstrate successful thickness determination of thin silicon lamellae using calibrated secondary electron detectors in a FIB-SEM dual-beam chamber. Unlike previous thickness measurement methods it does not require long acquisition times, the use of in-chamber scanning transmission electron microscope (STEM) or energy dispersive x-ray spectroscopy detectors. The calibration aligns a SEM image to an electron energy loss spectroscopy (EELS) map of lamella thickness acquired in a TEM. This calibration reveals the greyscale-thickness dependence of two secondary electron SEM detectors: the through-lens detector (TLD) and the in-chamber electron detector (ICE). It was found that lamella thickness estimation for TLD images is accurate for areas thinner than 0.4 t/λ, whilst ICE images are most accurate for areas thicker than 0.5 t/λ up to 1.1 t/λ. The procedure presented here allows objective lamella thickness determination during the final stages of FIB specimen preparation using conventional imaging modes for common secondary electron detectors. LAY DESCRIPTION: Successful analysis of a material in a transmission electron microscope requires very thin windows of the material to be fabricated. Despite the quality of this analysis relying heavily on the thickness of the window, measuring thickness during window fabrication is not common practice. The authors show that it is possible to measure the thickness of the window directly in a focused-ion-beam chamber with a scanning electron microscope without altering the fabrication procedure, and using electron detectors common to most microscopes.

Transport of hydrogen isotopes through interlayer spacing in van der Waals crystals

Atoms start behaving as waves rather than classical particles if confined in spaces commensurate with their de Broglie wavelength. At room temperature this length is only about one ångström even for the lightest atom, hydrogen. This restricts quantum-confinement phenomena for atomic species to the realm of very low temperatures^1-5. Here, we show that van der Waals gaps between atomic planes of layered crystals provide ångström-size channels that make quantum confinement of protons apparent even at room temperature. Our transport measurements show that thermal protons experience a notably higher barrier than deuterons when entering van der Waals gaps in hexagonal boron nitride and molybdenum disulfide. This is attributed to the difference in the de Broglie wavelengths of the isotopes. Once inside the crystals, transport of both isotopes can be described by classical diffusion, albeit with unexpectedly fast rates comparable to that of protons in water. The demonstrated ångström-size channels can be exploited for further studies of atomistic quantum confinement and, if the technology can be scaled up, for sieving hydrogen isotopes.

Body structure and composition of canoeists and kayakers: analysis of junior and teenage polish national canoeing team

The somatic build, biological age, general state of health, mental predisposition and physical fitness are the criteria for selection of individuals in competitive sport. The present study aims to analys the differences in body structure and composition of canoeists and kayakers and derive conclusions regarding the criteria for selection of individuals incompetitive sport. The research was conducted on a group of 32 men aged between 17 and 22: 16 kayakers and 16 Canadian canoeists of the junior and teenage Polish national canoeing team. Body composition was examined by means of bioelectrical segmental impedance. Body build type was determined using the anthropometric Heath-Carter method. Statistical analysis was performed using the Welch t-test. The examination of morphological features reveals significant differences in the studied parameters between the canoeists and kayakers. There are also significant differences between competitors of the Sydney 2000 Olympic Games and the studied group. We found that competitive kayakers should be taller than canoeists. The lower part of the body in kayakers is more developed than in canoeists and canoeists are more dehydrated than kayakers.

Whole-body cryostimulation in kayaker women: a study of the effect of cryogenic temperatures on oxidative stress after the exercise

AIM

The aim of this study was to determine the effect of whole-body cryostimulation on the activity of selected antioxidant enzymes and the concentration of lipid peroxidation products in kayaker women in the course of training.

METHODS

The study was performed on the group of 9 kayaker women, who underwent two training cycles: one typical ten-day training cycle and the another ten-day cycle preceded by cryostimulation sessions twice a day. The activity of antioxidant enzymes was assayed in erythrocytes, while the concentration of lipid peroxidation products was measured both in erythrocytes and in blood plasma.

RESULTS

A statistically significant increase in superoxide dismutase (SOD) and glutathione peroxidase (GPx) activity in erythrocytes and in concentration of conjugated dienes (CD) in blood plasma and erythrocytes and thiobarbituric acid reactive substances (TBARS) in plasma was revealed in kayaker women after the first six days of training without cryostimulation. Comparing two performed training cycles, after the first six days of training preceded by cryostimulation lower SOD and GPx activity in erythrocytes was detected, as well as lower CD levels in blood plasma and erythrocytes and lower TBARS concentration in blood plasma of kayaker women than after the six days of training without cryostimulation.

CONCLUSIONS

Whole-body cryostimulation improves the antioxidant capacity of organism exposed to intense exercise. Brief application of cryogenic temperatures is likely related to the activation of adaptive homeostatic mechanisms in accordance with the hormetic dose-response model.

Improvement in the face/name association performance after three months of physical training in elderly women

Several lines of evidence suggest that physical exercise not only influences the development of muscles, cardiovascular and respiratory systems, but also exerts a significant influence on the central nervous system. We examined the influence of strength and endurance training on cognitive performance in 33 healthy elderly volunteers (women, mean age 63.5 +/-4.5 yr) over a 3-month period of supervised training program. A control group consisted of 8 age-matched (mean age 66.3 +/-4.6) healthy volunteers who did not participate in any exercise training program. To evaluate the cognitive performance in our subjects we used two tests: face/name association test and Stroop test. The tests were applied shortly before and immediately after the training program. In the experimental group, a significant improvement in the association test performance, on average, from 71.6 +/-7.3% to 79.7 +/-7.2% (P<0.0001) was observed over the 3-month training period. There were no changes in the Stroop test results over the same time. Likewise, there were no changes in the control groups. Our data demonstrate that the training regime that is strictly followed over a relatively short period of time may improve the performance in associative memory tasks in elderly subjects. The study supports the notion that physical exercise influences cognitive performance and extend this notion to be valid for healthy elderly subjects.

Effect of altitude training on the peroxidation and antioxidant enzymes in sportsmen

PURPOSE

The aim of this work was an evaluation of the influence of physical exercise in high-altitude conditions (about 2000 m above sea level) on thiobarbituric acid reactive substances (TBARS) and superoxide dismutase (SOD) and catalase (CAT) activities in 10 kayakers and 10 rowers.

METHODS

During their training, the sportsmen performed different kinds of static and dynamic efforts. The blood samples were taken from the cubital vein on the control day at low altitude and at high altitude, and on the 4th, 10th, and 18th days of the training camp before and after exercise. The TBARS and lactic acid concentrations in blood plasma and SOD and CAT activities in erythrocytes were measured.

RESULTS

A statistically significant increase of SOD and CAT activities in erythrocytes after exercise on the 4th, 10th, and 18th days of training was found. The TBARS concentration in erythrocytes decreased in a statistically significant way after the end of the 10th day of exercise (P < 0.01), and on 18th day it more than doubled (P < 0.001) when preexercise values were compared with postexercise values of each day. A statistically significant increase of TBARS concentration in blood plasma was observed only after the end of exercise on the 10th day-using the same comparison as above. A statistically significant increased lactic acid concentration in blood plasma was noticed both on 4th or 18th days of training.

CONCLUSIONS

The results obtained show the increasing generation of oxygen-derived free radicals and the compensatory intensification of SOD and CAT activities after training in altitude (high mountain) conditions.

Poststimulatory pitch shifts for pure tones

Changes in the pitch of a short tone pulse (25 msec, 1000 HZ), following a leading tone, were measured at various leading-tone frequencies and for various time intervals between the leading tone and the tone pulse. The results show that poststimulatory pitch shifts away from the pitch of the leading tone are significant and reproducible. It is suggested that poststimulatory pitch shifts may influence the results of various psychoacoustic experiments on pitch perception.