Force-limiting and the mechanical response of natural turfgrass used in the National Football League: A step toward the elimination of differential lower limb injury risk on synthetic turf

Lower limb injury rate in the National Football League (NFL) is greater on synthetic turf than on natural turfgrass. Foot loading in potentially injurious situations can be mitigated by damage to natural turfgrass that limits the peak load by allowing relative motion between the foot and the ground. Synthetic turf surfaces do not typically sustain such damage and thus lack such a load-limiting mechanism. To guide innovation in synthetic turf design, this paper reports 1) the peak loads of natural turfgrass when loaded by a cleated footform and 2) corridors that define the load-displacement response. Kentucky bluegrass [Poa pratensis, L.] and two cultivars of hybrid bermudagrass [Cynodon dactylon (L.) Pers × C. transvaalensis Burtt Davy] were tested with two cleat patterns in three loading modes (anterior-posterior or AP translation, medial-lateral or ML translation, and forefoot external rotation) at two power levels (full-power, which generated potentially injurious loads, and reduced-power, which generated horizontal forces similar to non-injurious ground reaction forces applied by an elite athlete during play). All tests generated peak force<4.95 kN and torque<173 Nm, which is in a loading regime that would be expected to mitigate injury risk. In full-power tests, bermudagrass withstood significantly (p < 0.05) greater peak loads than Kentucky bluegrass: (3.86 ± 0.45 kN vs. 2.66 ± 0.23 kN in AP, 3.25 ± 0.45 kN vs. 2.49 ± 0.36 kN in ML, and 144.8 ± 12.0 Nm vs. 126.3 ± 6.1 Nm in rotation). Corridors are reported that describe the load-displacement response aggregated across all surfaces tested.

Homogeneous fields: Double expansion method, 3D printing/CNC realization, and verification by atomic magnetometry

In low-field magnetic resonance applications there is often an interest in creating homogeneous magnetic fields over unusual geometries, particularly when quantum magnetometers are involved. In this paper a design method is proposed, where both the surface current and magnetic field are expanded to find current coefficients that cancel out higher order field terms. Two coils are designed using this double expansion methodology: (1) a tuning field for a half-meter-long atomic magnetometer array and (2) a null field for a magnetometer to operate adjacent to an excitation solenoid. The field verification of the former shows the accuracy of CNC milling and the method proposed; a close analysis of the field signature in the latter revealed the limitations of 3D printing for precise scientific applications. Both coils are designed to be fifth-order error systems or better.

Toxicity Related to Radiotherapy Dose and Targeting Strategy: A Pooled Analysis of Cooperative Group Trials of Combined Modality Therapy for Locally Advanced Non-Small Cell Lung Cancer

OBJECTIVE

Concurrent chemoradiotherapy (CRT) was the standard treatment for locally advanced NSCLC (LA-NSCLC). This study was performed to examine thoracic radiotherapy (TRT) parameters and their impact on adverse events (AEs).

METHODS

We collected individual patient data from 3600 patients with LA-NSCLC who participated in 16 cooperative group trials of concurrent CRT. The TRT parameters examined included field design strategy (elective nodal irradiation [ENI] versus involved-field [IF] TRT [IF-TRT]) and TRT dose (60 Gy versus ≥60 Gy). The primary end point of this analysis was the occurrence of AEs. ORs for AEs were calculated with univariable and multivariable logistic models.

RESULTS

TRT doses ranged from 60 to 74 Gy. ENI was not associated with more grade 3 or higher AEs than IF-TRT was (multivariable OR = 0.77, 95% confidence interval [CI]: 0.543-1.102, p = 0.1545). Doses higher than 60 Gy (high-dose TRT) were associated with significantly more grade 3 or higher AEs (multivariable OR = 1.82, 95% CI: 1.501-2.203, p < 0.0001). In contrast, ENI was associated with significantly more grade 4 or higher AEs (multivariable OR = 1.33, 95% CI: 1.035-1.709, p = 0.0258). Doses higher than 60 Gy were also associated with more grade 4 or higher AEs (multivariate OR = 1.42, 95% CI: 1.191-1.700, p = 0.0001). Grade 5 AEs plus treatment-related deaths were more frequent with higher-dose TRT (p = 0.0012) but not ENI (p = 0.099).

CONCLUSIONS

For patients with LA-NSCLC treated with concurrent CRT, IF-TRT was not associated with the overall risk of grade 3 or higher AEs but was associated with significantly fewer grade 4 or higher AEs than ENI TRT. This is likely the result of irradiation of a lesser amount of adjacent critical normal tissue. Higher TRT doses were associated significantly with grade 3 or higher and grade 4 or higher AEs. On the basis of these findings and our prior report on survival, CRT using IF-TRT and 60 Gy (conventionally fractionated) were associated with more favorable patient survival and less toxicity than was the use of ENI or higher radiotherapy doses.