"Remove all impurities": a review of infection prevention and control measures in pre-Nightingale nursing

[Extract] Infection prevention and control measures such as hand hygiene, environmental cleaning and the use of personal protective equipment are used in health care to reduce the risk of transmitting infectious agents. The origin of many of these measures are credited to Florence Nightingale’s accomplishments in reducing the morbidity and mortality rates of British soldiers during the Crimean War (1854-1856) and are found in her seminal book, Notes on Nursing: What It Is and What It Is Not (1859). In Notes on Nursing, Nightingale highlighted to her audience the inextricable link between health and the sickroom environment and described basic infection prevention and control principles the caregiver should institute to restore health while limiting their risk of exposure to contagion. Even though Notes on Nursing was never written for vocational nursing, these guiding principles later formed the basis of the Nightingale model for nursing training and are collectively referred to as nursing’s first theory on environmental health. Despite the continual reverence for Nightingale’s contribution to infection prevention and control, little is known about the genesis of her ideas presented in Notes on Nursing nor their influences

Langtree's new sectional map of the state of Arkansas /

Relief shown by hachures."Entered according to Act of Congress in the year 1866, in the Clerks office of the District Court of the United States for the District of Arkansas, by G. McGowan."Printed by G.W. & C.B. Colton & Co

Gain from the two-envelope problem via information asymmetry: on the suboptimality of randomized switching

The two-envelope problem (or exchange problem) is one of maximizing the payoff in choosing between two values, given an observation of only one. This paradigm is of interest in a range of fields from engineering to mathematical finance, as it is now known that the payoff can be increased by exploiting a form of information asymmetry. Here, we consider a version of the 'two-envelope game' where the envelopes’ contents are governed by a continuous positive random variable. While the optimal switching strategy is known and deterministic once an envelope has been opened, it is not necessarily optimal when the content's distribution is unknown. A useful alternative in this case may be to use a switching strategy that depends randomly on the observed value in the opened envelope. This approach can lead to a gain when compared with never switching. Here, we quantify the gain owing to such conditional randomized switching when the random variable has a generalized negative exponential distribution, and compare this to the optimal switching strategy. We also show that a randomized strategy may be advantageous when the distribution of the envelope's contents is unknown, since it can always lead to a gain.Mark D. McDonnell, Alex J. Grant, Ingmar Land, Badri N. Vellambi, Derek Abbott and Ken Leve

The two-envelope problem revisited

The two-envelope problem has intrigued mathematicians for decades, and is a question of choice between two states in the presence of uncertainty. The problem so far, is considered open and there has been no agreed approach or framework for its analysis. In this paper we outline an elementary approach based on Cover's switching function that, in essence, makes a biased random choice where the bias is conditioned on the observed value of one of the states. We argue that the resulting symmetry breaking introduced by this process results in a gain counter to naive expectation. Finally, we discuss a number of open questions and new lines of enquiry that this discovery opens up. © 2010 World Scientific Publishing Company.Derek Abbott, Bruce R. Davis and Juan M. R. Parrond