Experimentally increased snow depth affects high Arctic microarthropods inconsistently over two consecutive winters.

Climate change induced alterations to winter conditions may affect decomposer organisms controlling the vast carbon stores in northern soils. Soil microarthropods are particularly abundant decomposers in Arctic ecosystems. We studied whether increased snow depth affected microarthropods, and if effects were consistent over two consecutive winters. We sampled Collembola and soil mites from a snow accumulation experiment at Svalbard in early summer and used soil microclimatic data to explore to which aspects of winter climate microarthropods are most sensitive. Community densities differed substantially between years and increased snow depth had inconsistent effects. Deeper snow hardly affected microarthropods in 2015, but decreased densities and altered relative abundances of microarthropods and Collembola species after a milder winter in 2016. Although increased snow depth increased soil temperatures by 3.2 °C throughout the snow cover periods, the best microclimatic predictors of microarthropod density changes were spring soil temperature and snowmelt day. Our study shows that extrapolation of observations of decomposer responses to altered winter climate conditions to future scenarios should be avoided when communities are only sampled on a single occasion, since effects of longer-term gradual changes in winter climate may be obscured by inter-annual weather variability and natural variability in population sizes.

Emissions from thaw ponds largely offset the carbon sink of northern permafrost wetlands.

Northern regions have received considerable attention not only because the effects of climate change are amplified at high latitudes but also because this region holds vast amounts of carbon (C) stored in permafrost. These carbon stocks are vulnerable to warming temperatures and increased permafrost thaw and the breakdown and release of soil C in the form of carbon dioxide (CO2) and methane (CH4). The majority of research has focused on quantifying and upscaling the effects of thaw on CO2 and CH4 emissions from terrestrial systems. However, small ponds formed in permafrost wetlands following thawing have been recognized as hotspots for C emissions. Here, we examined the importance of small ponds for C fluxes in two permafrost wetland ecosystems in northern Sweden. Detailed flux estimates of thaw ponds during the growing season show that ponds emit, on average (±SD), 279 ± 415 and 7 ± 11 mmol C m-2 d-1 of CO2 and CH4, respectively. Importantly, addition of pond emissions to the total C budget of the wetland decreases the C sink by ~39%. Our results emphasize the need for integrated research linking C cycling on land and in water in order to make correct assessments of contemporary C balances.

The respiratory, metabolic, and neuroendocrine effects of a new generation electronic control device.

INTRODUCTION: Electronic control devices (ECDs) have become popular in law enforcement because these devices have filled a gap left by other law enforcement devices, tactics, or tools and have been shown to reduce officer and suspect injuries. The TASER X3 is the latest generation device from the manufacturer. This device has the capability of firing three cartridges in a "semi-automatic" mode. This study is the first of the metabolic, neuroendocrine, and respiratory effects of this newer generation device. METHODS: This was a prospective, observational study of human subjects. A master instructor shot subjects with a TASER X3 in the anterior thorax with either one or two cartridges. Each subject received a 10-s exposure from the device. Vital signs were measured before and after the exposure. Venous pH, lactate, electrolytes, and catecholamines were measured before and after the exposure. Creatine kinase (CK) was measured before and at 24h post-exposure. Continuous spirometry was also performed. RESULTS: Fifty-three subjects completed the study. There were no important changes in vital signs or electrolytes. Venous pH, lactate, and catecholamine changes were similar to previous studies on earlier generation devices. There was no evidence of impairment of breathing. CK changes were greater for multiple "circuits". CONCLUSIONS: In our study, the respiratory, metabolic, and neuroendocrine effects were similar to previous generation devices. There was an increase in CK with more probes deployed.

Human cardiovascular effects of a new generation conducted electrical weapon.

OBJECTIVES: The conducted electrical weapon (CEW) is used by law enforcement to control potentially violent people. Much of the research in CEW safety has focused on the TASER X26, which uses a single deployment cartridge. New Generation CEW (NGCEW) technology has been developed that uses a different circuit and multiple cartridges that can be simultaneously deployed. The objective of this study is to examine the cardiovascular effects of the NGCEW in different deployment possibilities. METHODS: This was a prospective study of human subjects during NGCEW training courses. Subjects received a NGCEW probe deployment to the frontal torso in 1 of 3 configurations: 2, 3,or 4 embedded probes and then underwent a 10-s exposure. Before and after vital signs, electrocardiograms (ECGs), and serum troponin I values were obtained. Real-time echocardiography was utilized before, during and after the exposure to evaluate heart rate and rhythm. RESULTS: Initially, a 1st version NGCEW (NGCEWv1) that was in the final stages of manufacturer verification was used at the training courses. It had not been publicly released. During a NGCEWv1 exposure with 2 probes, there was an apparent brief episode of cardiac capture. Testing was halted and the manufacturer was notified. The device was redesigned and the study continued when a redesigned, 2nd version (NGCEWv2) was used. The NGCEW1 was studied in 8 subjects. The NGCEWv2 was studied in 45 subjects with no evidence of cardiac capture. There were no important post-exposure vital sign, troponin I or ECG changes found in any volunteers. CONCLUSIONS: An apparent brief myocardial capture event occurred with the NGCEWv1. This device was not released and was redesigned. The NGCEWv2 appears to exhibit a reasonable degree of cardiac safety with frontal torso exposures and multiple probe combination configurations.

The effect of an electronic control device on muscle injury as determined by creatine kinase enzyme.

The medical literature on the effect of electronic control devices (ECD) on muscle injury is sparse. In this paper, we examine pooled data from five human studies that used creatine kinase (CK) as a marker for muscle injury. CK was measured in five separate studies involving four TASER ECDs with different exposure durations and number of circuits or contact points. Device type, exposure duration, number of circuits or contact points, and CK values at baseline and 24 h after exposure were pooled from these previous studies. Data were analyzed to determine the correlation of CK to duration of exposure, number of contact points, and distance between the probes. The pooled results contained 163 subjects. Seven were withdrawn due to incomplete data, leaving 156 subjects for analysis (median age 36, range 19-67, 93.6% male). 121 (77.6%) subjects had 2 contacts points, 10 (6.4%) had 3 contact points, 18 (11.5%) had 4 contact points, and 7 (4.5%) had 6 contact points. 81 (51.9%) subjects had a 5-s exposure, 64 (41.0%) a 10-s exposure, and, 11 (7.1%) a 30-s exposure. Median baseline CK (145 U/l, IQR 104-217, range 12-1956) did not differ between groups (P = 0.213 for number of contact points, 0.124 for duration). For the number of contacts, the median change in CK for 2 points of contact was 32 (IQR -1 to 1513, range -205 to 1821), for 3 was 1456 (IQR 634-1868, range 101-25452), for 4 was 887 (IQR 285-7481, range -1054 to 7481), and for 6 was 846 (IQR 57-1149, range -8 to 2309), (P < 0.001). For duration, the median change in CK for 5 s was 26.5 (IQR -8 to 109, range -1054 to 2309), for 10 s was 303 (IQR 34.5-1073, range -205 to 25452), and for 30 s was 47 (IQR 23-82, range -140 to 364), (P < 0.001). There was a relationship between the number of points of contact and the change in CK (P < 0.001) but not a relationship between the duration and the change in CK (P = 0.496). The median spread between the probe pairs for our pooled data was 40 cm, with a range from 18 to 70 cm (n = 76). The correlation between the change in CK and spread between the probe pairs was 0.16 at baseline (P = 0.18), and 0.24 at 24 h (P = 0.04) by Spearman's rank correlation. ECD exposure can cause a modest increase in CK. Although we cannot draw conclusions about the individual devices included in this analysis, our findings indicated that multiple contact points or exposures may result in a larger increase in CK, but the duration of the exposure does not appear to have a significant effect on CK. There is a correlation between the distance between the probes and the change in CK.

Acidosis and catecholamine evaluation following simulated law enforcement "use of force" encounters.

OBJECTIVES: Law enforcement authorities are often charged with controlling resisting suspects. These encounters sometimes result in the sudden and unexpected death of the suspect. Drug intoxication, excited delirium syndrome, or excessive uses of force are factors that are often blamed, but sometimes the mechanism of these deaths is not fully understood. It is possible that worsening acidosis or excessive catecholamine release play a part. The objective of this study was to determine the effect on markers of acidosis and catecholamines of various tasks intended to simulate common arrest-related situations. METHODS: Subjects were assigned to one of five task groups: 1) a 150-meter sprint and wall hurdle (simulated flight from arrest); 2) 45 seconds of striking a heavy bag (simulated physical resistance); 3) a 10-second TASER X26 electronic control device exposure; 4) a fleeing and resistance exercise involving a law enforcement dog (K-9); or 5) an oleoresin capsicum (OC) exposure to the face and neck. Baseline serum pH, lactate, potassium, troponin I, catecholamines, and creatine kinase (CK) were evaluated. Serum catecholamines, pH, lactate, and potassium were sampled immediately after the task and every 2 minutes for 10 minutes posttask. Vital signs were repeated immediately after the task. Serum CK and troponin I were evaluated again at 24 hours posttask. RESULTS: Sixty-six subjects were enrolled; four did not complete their assigned task. One subject lost the intravenous (IV) access after completing the task and did not have data collected, and one subject only received a 5-second TASER device exposure and was excluded from the study, leaving 12 subjects in each task group. The greatest changes in acidosis markers occurred in the sprint and heavy bag groups. Catecholamines increased the most in the heavy bag group and the sprint group and increased to a lesser degree in the TASER, OC, and K-9 groups. Only the sprint group showed an increase in CK at 24 hours. There were no elevations in troponin I in any group, nor any clinically important changes in potassium. CONCLUSIONS: The simulations of physical resistance and fleeing on foot led to the greatest changes in markers of acidosis and catecholamines. These changes may be contributing or causal mechanisms in sudden custodial arrest-related deaths (ARDs). This initial work may have implications in guiding applications of force for law enforcement authorities (LEAs) when apprehending resisting subjects.

Effect of an electronic control device exposure on a methamphetamine-intoxicated animal model.

OBJECTIVES: Because of the prevalence of methamphetamine abuse worldwide, it is not uncommon for subjects in law enforcement encounters to be methamphetamine-intoxicated. Methamphetamine has been present in arrest-related death cases in which an electronic control device (ECD) was used. The primary purpose of this study was to determine the cardiac effects of an ECD in a methamphetamine intoxication model. METHODS: Sixteen anesthetized Dorset sheep (26-78 kg) received 0.0 mg/kg (control animals, n = 4), 0.5 mg/kg (n = 4), 1.0 mg/kg (n = 4), or 1.5 mg/kg (n = 4) of methamphetamine hydrochloride as a slow intravenous (IV) bolus during continuous cardiac monitoring. The animals received the following exposures in sequence from a TASER X26 ECD beginning at 30 minutes after the administration of the drug: 1) 5-second continuous exposure, 2) 15-second intermittent exposure, 3) 30-second intermittent exposure, and 4) 40-second intermittent exposure. Darts were inserted at the sternal notch and the cardiac apex, to a depth of 9 mm. Cardiac motion was determined by thoracotomy (smaller animals, < or = 32 kg) or echocardiography (larger animals, > 68 kg). Data were analyzed using descriptive statistics and chi-square tests. RESULTS: Animals given methamphetamine demonstrated signs of methamphetamine toxicity with tachycardia, hypertension, and atrial and ventricular ectopy in the 30-minute period immediately after administration of the drug. Smaller animals (n = 8, < or = 32 kg, mean = 29.4 kg) had supraventricular dysrhythmias immediately after the ECD exposures. Larger animals (n = 8, > 68 kg, mean = 72.4) had only sinus tachycardia after the exposures. One of the smaller animals had frequent episodes of ventricular ectopy after two exposures, including runs of delayed onset, nonsustained six- to eight-beat unifocal and multifocal ventricular tachycardia that spontaneously resolved. This animal had significant ectopy prior to the exposures as well. Thoracotomy performed on three smaller animals demonstrated cardiac capture during ECD exposure consistent with previous animal studies. In the larger animals, none of the methamphetamine-intoxicated animals demonstrated cardiac capture. Two control sheep showed evidence of capture similar to the smaller animals. No ventricular fibrillation occurred after the exposure in any animal. CONCLUSIONS: In smaller animals (32 kg or less), ECD exposure exacerbated atrial and ventricular irritability induced by methamphetamine intoxication, but this effect was not seen in larger, adult-sized animals. There were no episodes of ventricular fibrillation after exposure associated with ECD exposure in methamphetamine-intoxicated sheep.

Echocardiographic evaluation of a TASER-X26 application in the ideal human cardiac axis.

OBJECTIVES: TASER electronic control devices (ECDs) are used by law enforcement to subdue aggressive persons. Some deaths temporally proximate to their use have occurred. There is speculation that these devices can cause dangerous cardiac rhythms. Swine research supports this hypothesis and has reported significant tachyarrhythmias. It is not known if this occurs in humans. The objective of this study was to determine the occurrence of tachyarrhythmias in human subjects subjected to an ECD application. METHODS: This was a prospective, nonblinded study. Human volunteers underwent limited echocardiography before, during, and after a 10-second TASER X26 ECD application with preplaced thoracic electrodes positioned in the upper right sternal border and the cardiac apex. Images were analyzed using M-mode through the anterior leaflet of the mitral valve for evidence of arrhythmia. Heart rate (HR) and the presence of sinus rhythm were determined. Data were analyzed using descriptive statistics. RESULTS: A total of 34 subjects were enrolled. There were no adverse events reported. The mean HR prior to starting the event was 108.7 beats/min (range 65 to 146 beats/min, 95% CI = 101.0 to 116.4 beats/min). During the ECD exposure, the mean HR was 120.1 beats/min (range 70 to 158 beats/min, 95% CI = 112.2 to 128.0 beats/min) and a mean of 94.1 beats/min (range 55 to 121 beats/min, 95% CI = 88.4 to 99.7 beats/min) at 1 minute after ECD exposure. Sinus rhythm was clearly demonstrated in 21 (61.7%) subjects during ECD exposure (mean HR 121.4 beats/min; range 75 to 158 beats/min, 95% CI = 111.5 to 131.4). Sinus rhythm was not clearly demonstrated in 12 subjects due to movement artifact (mean HR 117.8 beats/min, range 70 to 152 beats/min, 95% CI = 102.8 to 132.8 beats/min). CONCLUSIONS: A 10-second ECD exposure in an ideal cardiac axis application did not demonstrate concerning tachyarrhythmias using human models. The swine model may have limitations when evaluating ECD technology.

Impact of conducted electrical weapons in a mentally ill population: a brief report.

INTRODUCTION: Conducted electrical weapons (CEWs) are used by some law enforcement agencies to subdue mentally ill subjects who are combative, violent, or suicidal. The use of CEWs in this population is controversial. Proponents advocate CEW use to avoid other forms of escalated force. Opponents advocate against CEW use because of the potential for abuse. What is lacking in the medical literature is documentation of the impact on outcome that this technology may have when used in this population. This project represents an initial report in this area. METHODS: A database of CEW use has been maintained since 1999 to which law enforcement agencies voluntarily report. This database was reviewed for occurrences of CEW use on mentally ill and suicidal subjects. Situation outcome and potential for law enforcement use of deadly force as an alternative were recorded. Data analysis was performed using descriptive statistics. RESULTS: There were 10,608 reports of CEW use over a 72-month period. Of these, there were 2452 uses on mentally ill subjects; and of these, 1111 (45.3%) were in situations where lethal force by the law enforcement agency would have been justified or where the subject represented an imminent life threat to himself. CONCLUSION: The mentally ill represents a significant portion of subjects upon whom CEWs are used. These data suggest frequent use of CEWs in situations where deadly force would otherwise be justified and in situations where subjects exhibit imminent danger to themselves. These data also suggest that escalation to deadly force was avoided in many mental illness and suicidal situations by the presence of a CEW.