Autonomic computing systems are designed to be self-diagnosing and self-healing, such that they detect performance and correctness problems, identify their causes, and react accordingly. These abilities can improve performance, availability, and security, while simultaneously reducing the effort and skills required of system administrators. One way that systems can support these abilities is by allowing monitoring code, diagnostic code, and function implementations to be dynamically inserted and removed in live systems. This "hot swapping" avoids the requisite prescience and additional complexity inherent in creating systems that have all possible configurations built in ahead of time. For already-complex pieces of code such as operating systems, hot swapping provides a simpler, higher-performance, and more maintainable method of achieving autonomic behavior. In this paper, we discuss hot swapping as a technique for enabling autonomic computing in systems software. First, we discuss its advantages and describe the required system structure. Next, we describe K42, a research operating system that explicitly supports interposition and replacement of active operating system code. Last, we describe the infrastructure of K42 for hot swapping and several instances of its use demonstrating autonomic behavior.As computer systems become more complex, they become more difficult to administer properly. Special training is needed to configure and maintain modern systems, and this complexity continues to increase. Autonomic computing systems address this problem by managing themselves. Central to autonomic computing is the ability of a system to identify problems and to reconfigure itself in order to address them. In this paper, we investigate hot swapping as a technology that can be used to address systems software's autonomic requirements. Hot swapping is accomplished either by interpositioning of code, or by replacement of code. Interpositioning involves inserting a new component between two existing ones. This allows us, for example, to enable more detailed monitoring when problems occur, while minimizing run-time costs when the system is performing acceptably. Replacement allows an active component to be switched with a different implementation of that component while the system is running, and while applications continue to use resources managed by that component. As conditions change, upgraded components, better suited to the new environment, dynamically replace the ones currently active.

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Anatomic variants in the right atrium are under-recognized and under-reported phenomena in cardiac imaging. In the fetus, right atrium serves as a conduit for oxygenated blood to be delivered to the left heart bypassing the right ventricle and the nonfunctional lungs. The anatomy in the fetal right atrium is designed for such purposeful circulation. The right and left venous valves are prominent structures in the fetal heart that direct inferior vena caval flow towards the foramen ovale. These anatomic structures typically regress and the foramen ovale closes after birth. However, the venous valves can persist leading to a range of anatomic, physiological, and pathological consequences in the adult. We describe various presentations of persistent venous valves, focusing on the right venous valve in this illustrated multimodality imaging article.

Anesthesiologists use several classes of medications that target the central nervous system (CNS) for nonanesthetic use to treat side effects, mitigate risk of complications and treat postoperative pain. In addition, many patients will be on chronic medications that are CNS active, and understanding anesthetic implications is of the utmost importance for the practicing anesthesiologist. Of particular importance are medications used to treat patients with chronic opioid use disorder, such as methadone, naltrexone, and buprenorphine. This chapter is an overview of CNS-active medications that are commonly used outside of the operating room that are imperative to know for the physician anesthesiologist.