Philosophy's loss, neurology's gain:the endeavor of John Hughlings-Jackson

The year 2011 marked the centenary of the death of one of the founders of British neurology, John Hughlings-Jackson (1835-1911). By common consent he was a great clinician. But he was more. He endeavored to use clinical observations to throw light on one of the great problems of the modern world, the problem of mind. Hughlings-Jackson's daily contact with mentalities warped by neurological disease caused him to ponder deeply the nature of the mind-brain relationship, nowadays often known simply as the "hard problem. " In particular, he saw the danger of conflating mind and brain, a danger that has grown greater with the spectacular growth of neuroscientific knowledge during the last century. Although Hughlings-Jackson's neuroscientific thought is long outdated, his philosophic endeavors remain highly instructive. © 2012 by The Johns Hopkins University Press.

The epileptology of Theodore Herpin (1799-1865)

The Frenchman, Theodore Herpin (1799-1865), in Des Acces Incomplets d'Epilepsie, published posthumously in 1867, provided a very detailed account of a wide range of the possible manifestations of nonconvulsive epileptic seizures. However, he did not note the presence of absence seizures in any of his 300 patients who had experienced, at least in some of their attacks, what he considered were incomplete manifestations of epilepsy, the word epilepsy being taken to refer to full generalized tonic-clonic seizures. In the one patient, Herpin recognized that all epileptic seizures, whether complete or incomplete, began in the same way, and deduced that they must originate in the same place in that patient's brain. He did not develop the latter idea further. His observations, and his interpretation of them, seem to have preceded John Hughlings Jackson's independent development of similar concepts, but Jackson's more extensive intellectual exploration of the implications of his observations made him a more important figure than Herpin in the history of epileptology.

The epileptology of William Aldren Turner

William Aldren Turner (1864-1945), in his day Physician to the National Hospital, Queen Square, and to King's College Hospital, London, was one of the major figures in the world of epileptology in the period between Hughlings Jackson in the latter part of the 19th century and the advent of electroencephalography in the 1930s. Although he also made contributions to knowledge in other areas of neurology, and with Grainger Stewart wrote a competent textbook on that subject, Turner's main professional interest throughout his career seems to have been epilepsy. On the basis of a series of earlier, rather heavily statistical, personal publications dealing with various aspects of the disorder, he authored what became a well-accepted monograph entitled Epilepsy-a study of the idiopathic disorder, which appeared in 1907, and he also gave the 1910 Morison lectures in Edinburgh on the topic. His writings on epilepsy over a period of three decades consolidated knowledge rather than led to significant advances, but helped maintain interest in the disorder during a rather long fallow phase in the development of the understanding of its nature. (C) 2005 Elsevier Ltd. All rights reserved.

Water Flow Through the Gills of Port Jackson Sharks

Evidence is presented for the existence of a countercurrent flow between water and blood at the respiratory surfaces of the Port Jackson shark gill.

Spectral properties of the tandem Jackson network, seen as a quasi-birth-and-death process

Quasi-birth-and-death (QBD) processes with infinite “phase spaces” can exhibit unusual and interesting behavior. One of the simplest examples of such a process is the two-node tandem Jackson network, with the “phase” giving the state of the first queue and the “level” giving the state of the second queue. In this paper, we undertake an extensive analysis of the properties of this QBD. In particular, we investigate the spectral properties of Neuts’s R-matrix and show that the decay rate of the stationary distribution of the “level” process is not always equal to the convergence norm of R. In fact, we show that we can obtain any decay rate from a certain range by controlling only the transition structure at level zero, which is independent of R. We also consider the sequence of tandem queues that is constructed by restricting the waiting room of the first queue to some finite capacity, and then allowing this capacity to increase to infinity. We show that the decay rates for the finite truncations converge to a value, which is not necessarily the decay rate in the infinite waiting room case. Finally, we show that the probability that the process hits level n before level 0 given that it starts in level 1 decays at a rate which is not necessarily the same as the decay rate for the stationary distribution.

Efficient simulation of a Tandem Jackson Network

The two-node tandem Jackson network serves as a convenient reference model for the analysis and testing of different methodologies and techniques in rare event simulation. In this paper we consider a new approach to efficiently estimate the probability that the content of the second buffer exceeds some high level L before it becomes empty, starting from a given state. The approach is based on a Markov additive process representation of the buffer processes, leading to an exponential change of measure to be used in an importance sampling procedure. Unlike changes of measures proposed and studied in recent literature, the one derived here is a function of the content of the first buffer. We prove that when the first buffer is finite, this method yields asymptotically efficient simulation for any set of arrival and service rates. In fact, the relative error is bounded independent of the level L; a new result which is not established for any other known method. When the first buffer is infinite, we propose a natural extension of the exponential change of measure for the finite buffer case. In this case, the relative error is shown to be bounded (independent of L) only when the second server is the bottleneck; a result which is known to hold for some other methods derived through large deviations analysis. When the first server is the bottleneck, experimental results using our method seem to suggest that the relative error is bounded linearly in L.

Tradução, Adaptação e Validação para o Português da Escala de Sunderland e da Escala Revista de Cubbin & Jackson

Objetivo: Traduzir para o português e avaliar as propriedades de medidas da Escala de Sunderland e da Escala Revista de Cubbin & Jackson, instrumentos cuja finalidade é avaliar o risco de desenvolvimento de úlceras por pressão em terapia intensiva. Métodos: O estudo compreendeu os processos de tradução e de adaptação das escalas à língua portuguesa, bem como o processo de validação dos instrumentos em estudo. A amostra foi constituída por 90 pacientes internados na unidade de terapia intensiva. Na avaliação da fiabilidade, foram identificados valores de alfa de Cronbach de 0,702 e de 0,708 para a Escala de Sunderland e a Escala Revista de Cubbin & Jackson, respectivamente. A validação de critério (preditiva) foi realizada comparativamente com a Escala de Braden (padrão-ouro), sendo as principais medidas avaliadas a sensibilidade, a especificidade, o valor preditivo positivo, o valor preditivo negativo e a área sob uma curva,que foram calculadas com base nos pontos de corte definidos pelos autores. Resultados: A Escala de Sunderland obteve 60% de sensibilidade, 86,7% de especificidade, 47,4% de valor preditivo positivo, 91,5% de valor preditivo negativo e 0,86 para a área sob uma curva. A Escala Revista de Cubbin & Jackson obteve 73,3% de sensibilidade, 86,7% de especificidade, 52,4% de valor preditivo positivo, 94,2% de valor preditivo negativo e 0,91 para a área sob uma curva. A Escala de Braden obteve 100% de sensibilidade, 5,3% de especificidade, 17,4% de valor preditivo positivo, 100% de valor preditivo negativo e 0,72 para a área sob uma curva. Conclusão: Ambos os instrumentos demonstram possuir fiabilidade e validade para a utilização. Nessa amostra, a Escala Revista de Cubbin & Jackson obteve melhores valores preditivos para desenvolvimento de úlceras por pressão em terapia intensiva.

Icones filicum ad eas potissimum species illustrandas destinatæ, quæ hactenus, vel in herbariis delituerunt prorsus incognitae, vel saltem nondum per icones botanicis innotuerunt.Figures and descriptions of ferns, principally of such as have been altogether unnoticed by botanists, or as have not yet been correctly figured.By William Jackson Hooker and Robert Kaye Greville.

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Icones filicum ad eas potissimum species illustrandas destinatæ, quæ hactenus, vel in herbariis delituerunt prorsus incognitae, vel saltem nondum per icones botanicis innotuerunt.Figures and descriptions of ferns, principally of such as have been altogether unnoticed by botanists, or as have not yet been correctly figured.By William Jackson Hooker and Robert Kaye Greville.

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