The Effect of Tactical Tasks and Gear on Muscle Activation of SWAT Officers

Special Weapons and Tactics (SWAT) officers constitute a subgroup of specialized law enforcement officers that perform a variety of tactical operations while wearing approximately 40 kg of tactical gear. Lower back pain is a prevalent musculoskeletal injury suffered by SWAT officers. Tactical gear places significant stress on the lower back. Thus, it is important to quantify the effect that tactical gear has on muscle activation levels of torso musculature while performing occupational tasks. Electromyography was evaluated on 20 male subjects (age: 34.7±4.5 yr.; height: 1.79±.10 m; body mass: 91.53±17.32 kg; mass of gear: 13.82±1.90 kg) while performing four tactical tasks (standing, rifle walk, sitting, & shield walk) with and without gear. Electromyography was evaluated bilaterally on the erector spinae, rectus abdominis, and external oblique muscles. The dominant erector spinae (mean delta: +0.16%) and external oblique (mean delta: -0.124%) demonstrated significant changes in muscle activation with the addition of gear, which may indicate increased spinal compression. There were also trends of increased co-activation of core musculature with the addition of gear. The rifle walk and shield walk task mean muscle activations were significantly higher than the standing and sitting tasks. The shield walk produced the highest mean activations for each muscle. Physical training for SWAT officers should emphasize exercises that simulate task-specific movement patterns without gear to decrease the spinal compression associated with load carriage

Dynamics of cloud-top generating cells in winter cyclones

Recent field observations suggest that cloud-top precipitation generating cells (GCs) are ubiquitous in the warm-frontal and comma-head regions of midlatitude winter cyclones. The presence of fall streaks emanating from the GCs, and their persistence either to the surface or until merging into precipitation bands suggests that GCs are a critical component of the precipitation process in these cyclones. This dissertation assesses the influence of radiative forcing and a range of cloud-top stability profiles on the development and maintenance of cloud top generating cells (GCs) in high-resolution (100 m grid spacing) idealized Weather Research and Forecasting model (WRF) simulations with initial conditions representative of the vertical structure of a cyclone observed during the Profiling of Winter Storms (PLOWS) campaign. First, sensitivity to radiative forcing under stability and shear representative of the 14-15 February 2010 cyclone observed during PLOWS was assessed in three simulations with: longwave only (night), longwave and shortwave (day), and no radiation parameterization. Simulated GC kinematics, structure, and ice mass for the nighttime simulation are shown to compare well with Wyoming Cloud Radar, cloud probe, and other PLOWS observations from overnight on 14-15 February 2010. The domain-averaged longwave cooling rate in the day and night simulations were both in excess of 0.5 K h-1 near cloud top, with maxima > 2 K h-1 commonly observed atop GCs. Shortwave warming was weaker by comparison, with domain-averaged values 0.1 – 0.2 K h-1 and maxima of 0.5 K h-1 atop GCs. The stabilizing influence of cloud-top shortwave warming was evident in the daytime simulation’s vertical velocity spectrum, with the 99th percentile of vertical velocity in the 6 – 8 km layer of 1.2 m s-1, compared to 1.8 m s-1 for the nighttime simulation. GCs regenerate in simulations with radiative forcing after the initial stability is released, but do not persist in simulations when radiation is not parameterized, demonstrating that radiative forcing is critical to GC maintenance under the thermodynamic and vertical wind shear conditions present in this cyclone. When present, GCs are characterized by high ice supersaturation (RHice > 150%) and latent heating rates frequently in excess of 2 K h-1 collocated with vertical velocity maxima. Precipitation mixing ratio maxima of > 0.15 g kg-1 were common within GCs in both the daytime and nighttime simulations. Second, the influence of cloud-top instability paired with nighttime, daytime, or no radiative forcing on the development and maintenance (or lack) of GCs is assessed. Under initially unstable conditions, GCs develop regardless of radiative forcing, but only persist clearly with radiative forcing. Cloud-top destabilization due to longwave cooling leads to development of GCs even under initially neutral and stable conditions, supporting the hypothesis that GCs are ubiquitous atop winter cyclones because of radiative forcing. GCs do not develop in initially stable simulations with no radiation. Decreased range in vertical velocity spectra for daytime radiative forcing simulations is consistent with offset of cloud-top destabilization through longwave cooling by shortwave heating

Predictors of Arterial Stiffness in Law Enforcement Officers

Background: Compare arterial stiffness among law enforcement officers (LEOs) versus general population normative values and identify predictors of arterial stiffness in LEOs. Methods: Seventy male LEOs (age: 24–54 years) completed body composition, blood pressures, physical activity level, and carotid-femoral pulse wave velocity (cfPWV) measurements. T-tests and regression analyses were utilized to compare LEO data to normative data and predict cfPWV, respectively. Results: Compared to similar age strata within the general population, cfPWV was lower among LEO’s under 30-years (mean difference = −0.6 m·s−1), but higher among LEOs 50–55-years (mean difference = 1.1 m·s−1). Utilizing regression, age, relative body fat, and diastolic blood pressure explained the greatest variance in LEO’s cfPWV (adj. R2 = 0.56, p \u3c 0.001). Conclusion: This investigation demonstrated that arterial stiffness may progress more rapidly in LEOs and LEOs’ relative body fat and blood pressure may primarily affect arterial stiffness and risk of CVD

Dynamics of Cloud-Top Generating Cells in Winter Cyclones. Part III: Shear and Convective Organization

Cloud-top generating cells (GCs) are a common feature atop stratiform clouds within the comma head of winter cyclones. The dynamics of cloud-top GCs are investigated using very high-resolution idealized WRF Model simulations to examine the role of shear in modulating the structure and intensity of GCs. Simulations were run for the same combinations of radiative forcing and instability as in Part II of this series, but with six different shear profiles ranging from 0 to 10ms21 km21 within the layer encompassing the GCs. The primary role of shear was to modulate the organization of GCs, which organized as closed convective cells in simulations with radiative forcing and no shear. In simulations with shear and radiative forcing, GCs organized in linear streets parallel to the wind. No GCs developed in the initially stable simulations with no radiative forcing. In the initially unstable and neutral simulations with no radiative forcing or shear, GCs were exceptionally weak, with no clear organization. In moderate-shear (Du/Dz 5 2, 4ms21 km21) simulations with no radiative forcing, linear organization of the weak cells was apparent, but this organization was less coherent in simulations with high shear (Du/Dz 5 6, 8, 10ms21 km21). The intensity of the updrafts was primarily related to the mode of radiative forcing but was modulated by shear. The more intense GCs in nighttime simulations were either associated with no shear (closed convective cells) or strong shear (linear streets). Updrafts within GCs under conditions with radiative forcing were typically ;1–2 ms21 with maximum values , 4ms21

Effect of angiotensin-converting enzyme inhibitor and angiotensin receptor blocker initiation on organ support-free days in patients hospitalized with COVID-19

IMPORTANCE Overactivation of the renin-angiotensin system (RAS) may contribute to poor clinical outcomes in patients with COVID-19. Objective To determine whether angiotensin-converting enzyme (ACE) inhibitor or angiotensin receptor blocker (ARB) initiation improves outcomes in patients hospitalized for COVID-19. DESIGN, SETTING, AND PARTICIPANTS In an ongoing, adaptive platform randomized clinical trial, 721 critically ill and 58 non–critically ill hospitalized adults were randomized to receive an RAS inhibitor or control between March 16, 2021, and February 25, 2022, at 69 sites in 7 countries (final follow-up on June 1, 2022). INTERVENTIONS Patients were randomized to receive open-label initiation of an ACE inhibitor (n = 257), ARB (n = 248), ARB in combination with DMX-200 (a chemokine receptor-2 inhibitor; n = 10), or no RAS inhibitor (control; n = 264) for up to 10 days. MAIN OUTCOMES AND MEASURES The primary outcome was organ support–free days, a composite of hospital survival and days alive without cardiovascular or respiratory organ support through 21 days. The primary analysis was a bayesian cumulative logistic model. Odds ratios (ORs) greater than 1 represent improved outcomes. RESULTS On February 25, 2022, enrollment was discontinued due to safety concerns. Among 679 critically ill patients with available primary outcome data, the median age was 56 years and 239 participants (35.2%) were women. Median (IQR) organ support–free days among critically ill patients was 10 (–1 to 16) in the ACE inhibitor group (n = 231), 8 (–1 to 17) in the ARB group (n = 217), and 12 (0 to 17) in the control group (n = 231) (median adjusted odds ratios of 0.77 [95% bayesian credible interval, 0.58-1.06] for improvement for ACE inhibitor and 0.76 [95% credible interval, 0.56-1.05] for ARB compared with control). The posterior probabilities that ACE inhibitors and ARBs worsened organ support–free days compared with control were 94.9% and 95.4%, respectively. Hospital survival occurred in 166 of 231 critically ill participants (71.9%) in the ACE inhibitor group, 152 of 217 (70.0%) in the ARB group, and 182 of 231 (78.8%) in the control group (posterior probabilities that ACE inhibitor and ARB worsened hospital survival compared with control were 95.3% and 98.1%, respectively). CONCLUSIONS AND RELEVANCE In this trial, among critically ill adults with COVID-19, initiation of an ACE inhibitor or ARB did not improve, and likely worsened, clinical outcomes. TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT0273570