Left ventricular rotation: a neglected aspect of the cardiac cycle

Purpose: To describe the mechanics and possible clinical importance of left ventricular (LV) rotation, exemplify techniques to quantify LV rotation and illustrate the temporal relationship of cardiac pressures, electrocardiogram and LV rotation. Materials and methods: Review of the literature combined with selected examples of echocardiographic measurements. Results: Rotation of the left ventricle around its longitudinal axis is an important but thus far neglected aspect of the cardiac cycle. LV rotation during systole maximizes intracavitary pressures, increases stroke volume, and minimizes myocardial oxygen demand. Shearing and restoring forces accumulated during systolic twisting are released during early diastole and result in diastolic LV untwisting or recoil promoting early LV filling. LV twist and untwist are disturbed in a number of cardiac diseases and can be influenced by several therapeutic interventions by altering preload, afterload, contractility, heart rate, and/or sympathetic tone. Conclusions: The concept of LV twisting and untwisting closely linking LV systolic and diastolic function may carry potential diagnostic and therapeutic importance for the management of critically ill patients. Future clinical studies need to address the feasibility of assessing LV twist and untwist as well as the relevance of its therapeutic modulation in critically ill patient

Eroding Potentiometers

Eroding potentiometers have been devised for measuring the time-dependent positions of char fronts advancing through layers of insulating material subject to intense heating from one side. In the original application, the material layers of interest are thermal insulators in rocket motors and the heat comes from firing of the motors, but the principle of operation is equally applicable to other insulating materials subject to intense heating (e.g., ablative fire-retardant materials). Measuring the thickness decrement of propellant (in hybrid motors in particular) is another possible application of this transducer. Telemetry informs mission control of the propellant left after each burn. An eroding potentiometer could be characterized, more precisely, as an eroding two-wire resistor. It includes a twisted pair of thin, insulated wires oriented along the thickness of, and embedded in, the layer of thermal-insulation material to be tested (see figure). The electrical insulation material on the wires should be one for which the charring temperature is about the same as (or perhaps slightly less than) that of the thermal- insulation material to be tested. In the original rocket-motor application, the wires have a diameter of 0.003 in. (.0.08 mm), are made of manganin, and are coated with polyimide for electrical insulation. Outside the thermal insulation on the cold side, the wire leads are connected to a Wheatstone bridge circuit for measurement of electrical resistance change

Exercise Improves Vascular Dilator Reactivity in Chronically Stressed Rats with Pre-existing Metabolic Syndrome

Please refer to the pdf version of the abstract located adjacent to the title

The Green New Deal and Green Transitions

In February 2019, Representative Ocasio-Cortez and Senator Markey introduced a Green New Deal Resolution in Congress, calling for a tenyear mobilization toward action on climate change, socioeconomic inequality, and other issues. A Green New Deal--evoking the language of FDR-erapolicy--envisions a transition to a green economy that is integrated with concern for the social and economic welfare of those who are most harmed by environmental degradation and those who are most likely to be displaced by the reinvention ofU.S. infrastructure and energy systems. This Article addresses the need for engaging with regulatory transition theory in order to assess the legal, policy design, and implementation challenges of a Green New Deal. Regulatory transition theory explains how economic, legal, and political pressures can lead to policies that are counterproductive, unjust, and inefficient. Key examples of this phenomenon are found throughout the core U.S. environmental-legal framework, which has been plagued by overly generous transition relief in the grandfathering of aging infrastructure and through other policies that differentiate between new and existing sources. This history provides important lessons for designing a Green New Deal around four principles: equity, efficacy, efficiency, and political coalition-building. Some solutions for transitions that can be effectively implemented may be intuitive but must overcome political economy challenges and legal barriers

Green Transitions in a COVID Economy

As many elements of a Green New Deal languished in Congress, economic policy took dramatic turns instead to address a different crisis: the Covid-19 pandemic. This Essay explores the way in which legal and policy responses to Covid-19 in the United States—particularly as discourse has focused on the impacts of Covid-19 response on labor markets—may provide insight into the political economy of a Green New Deal. New federal spending toward a just transition is structurally much easier to accomplish than developing new regulatory policy through legislation or executive action and avoids judicial policing of administrative authority