Mechanics of CPR Performed with the Patient on a Soft Bed Versus a Hard Surface

Objective: To study the effects of underlying bed softness versus stiffness on the effectiveness of chest compressions in CPR. Methods: For a wide range of bed stiffness constants, mathematical models describing compression of the human chest supported by a hospital bed were created for an adult thorax experiencing either a sinusoidal compressive force or a sinusoidal sternal displacement. Results: With 5 cm peak displacement, sternum-to-spine compression fell from 4.3 to 1.0 cm, and peak power fell from 59 to 23 Watts, as bed stiffness decreased from 50,000 to 5,000 N/m. Less than 35% of maximal chest compression occurred at a typical bed stiffness of 10,000 N/m. With 400 N peak force, sternum-to-spine compression decreased from 5.0 to 2.0 cm, and peak power increased from 82 to 226 Watts, as bed stiffness decreased from 50,000 to 5,000 N/m. However, greater than 85% of maximal chest compression was obtained at a typical bed stiffness of 10,000 N/m. Conclusion: The deterioration of chest compression performed on soft beds is technique dependent. If necessary, CPR can be performed effectively on a softer surface using a constant peak force technique. However, a firm surface is most desirable

Breeding Yellow-flowered Alfalfa for Combined Wildlife Habitat and Forage Purposes

The objectives of our research were to: • evaluate a wide array of alfalfa germplasm containing varied levels of M. sativa ssp. falcata for traits related to suitability for stockpiling and nesting cover for game birds, •compare yellow-flowered cultivars and germplasms to conventional hay- and pasture-type cultivars for forage yield and quality in a delayed single-harvest / production system, and • develop, by phenotypic selection, one or more synthetic cultivars of yellow-flowered alfalfa that would have high forage yield, tolerance to potato leafhopper yellowing, prolonged flowering, and good leaf retention under a stockpiling management system until mid-July

First cohomology for finite groups of Lie type: simple modules with small dominant weights

Let $k$ be an algebraically closed field of characteristic $p > 0$, and let $G$ be a simple, simply connected algebraic group defined over $\mathbb{F}_p$. Given $r \geq 1$, set $q=p^r$, and let $G(\mathbb{F}_q)$ be the corresponding finite Chevalley group. In this paper we investigate the structure of the first cohomology group $H^1(G(\mathbb{F}_q),L(\lambda))$ where $L(\lambda)$ is the simple $G$-module of highest weight $\lambda$. Under certain very mild conditions on $p$ and $q$, we are able to completely describe the first cohomology group when $\lambda$ is less than or equal to a fundamental dominant weight. In particular, in the cases we consider, we show that the first cohomology group has dimension at most one. Our calculations significantly extend, and provide new proofs for, earlier results of Cline, Parshall, Scott, and Jones, who considered the special case when $\lambda$ is a minimal nonzero dominant weight.Comment: 24 pages, 5 figures, 6 tables. Typos corrected and some proofs streamlined over previous versio