Descartes, corpuscles and reductionism : mechanism and systems in Descartes' physiology

I argue that Descartes explains physiology in terms of whole systems, and not in terms of the size, shape and motion of tiny corpuscles (corpuscular mechanics). It is a standard, entrenched view that Descartes’s proper means of explanation in the natural world is through strict reduction to corpuscular mechanics. This view is bolstered by a handful of corpuscular-mechanical explanations in Descartes’s physics, which have been taken to be representative of his treatment of all natural phenomena. However, Descartes’s explanations of the ‘principal parts’ of physiology do not follow the corpuscular–mechanical pattern. Des Chene (2001) has identified systems in Descartes’s account of physiology, but takes them ultimately to reduce down to the corpuscle level. I argue that they do not. Rather, Descartes maintains entire systems, with components selected from multiple levels of organisation, in order to construct more complete explanations than corpuscular mechanics alone would allow

Two-photon resonant excitation of interatomic coulombic decay in neon dimers

The recent availability of intense and ultrashort extreme ultraviolet sources opens up the possibility of investigating ultrafast electronic relaxation processes in matter in an unprecedented regime. In this work we report on the observation of two-photon excitation of interatomic Coulombic decay (ICD) in neon dimers using the tunable intense pulses delivered by the free electron laser FERMI. The unique characteristics of FERMI (narrow bandwidth, spectral stability, and tunability) allow one to resonantly excite specific ionization pathways and to observe a clear signature of the ICD mechanism in the ratio of the ion yield created by Coulomb explosion. The present experimental results are explained by ab initio electronic structure and nuclear dynamics calculations

A randomized controlled trial of tai chi for long-term low back pain (TAI CHI): Study rationale, design, and methods

<p>Abstract</p> <p>Background</p> <p>Low back pain persisting for longer than 3 months is a common and costly condition for which many current treatments have low-moderate success rates at best. Exercise is among the more successful treatments for this condition, however, the type and dosage of exercise that elicits the best results is not clearly defined. Tai chi is a gentle form of low intensity exercise that uses controlled movements in combination with relaxation techniques and is currently used as a safe form of exercise for people suffering from other chronic pain conditions such as arthritis. To date, there has been no scientific evaluation of tai chi as an intervention for people with back pain. Thus the aim of this study will be to examine the effects of a tai chi exercise program on pain and disability in people with long-term low back pain.</p> <p>Methods and design</p> <p>The study will recruit 160 healthy individuals from the community setting to be randomised to either a tai chi intervention group or a wait-list control group. Individuals in the tai chi group will attend 2 tai chi sessions (40 minutes)/week for 8 weeks followed by 1 tai chi session/week for 2 weeks. The wait-list control will continue their usual health care practices and have the opportunity to participate in the tai chi program once they have completed the follow-up assessments. The primary outcome will be bothersomeness of back symptoms measured with a 0–10 numerical rating scale. Secondary outcomes include, self-reports of pain-related disability, health-related quality of life and global perceived effect of treatment. Statistical analysis of primary and secondary outcomes will be based on the intention to treat principle. Linear mixed models will be used to test for the effect of treatment on outcome at 10 weeks follow up. This trial has received ethics approval from The University of Sydney Human Research Ethics Committee. HREC Approval No.10452</p> <p>Discussion</p> <p>This study will be the first trial in this area and the information on its effectiveness will allow patients, clinicians and treatment funders to make informed choices regarding this treatment.</p> <p>Trial Registration</p> <p>This trial has been registered with Australian New Zealand Clinical Trials Registry. <b>ACTRN12608000270314</b></p

The material soul: Strategies for naturalising the soul in an early modern epicurean context

We usually portray the early modern period as one characterised by the ‘birth of subjectivity’ with Luther and Descartes as two alternate representatives of this radical break with the past, each ushering in the new era in which ‘I’ am the locus of judgements about the world. A sub-narrative called ‘the mind-body problem’ recounts how Cartesian dualism, responding to the new promise of a mechanistic science of nature, “split off” the world of the soul/mind/self from the world of extended, physical substance—a split which has preoccupied the philosophy of mind up until the present day. We would like to call attention to a different constellation of texts—neither a robust ‘tradition’ nor an isolated ‘episode’, somewhere in between—which have in common their indebtedness to, and promotion of an embodied, Epicurean approach to the soul. These texts follow the evocative hint given in Lucretius’ De rerum natura that ‘the soul is to the body as scent is to incense’ (in an anonymous early modern French version). They neither assert the autonomy of the soul, nor the dualism of body and soul, nor again a sheer physicalism in which ‘intentional’ properties are reduced to the basic properties of matter. Rather, to borrow the title of one of these treatises (L’Âme Matérielle), they seek to articulate the concept of a material soul. We reconstruct the intellectual development of a corporeal, mortal and ultimately material soul, in between medicine, natural philosophy and metaphysics, including discussions of Malebranche and Willis, but focusing primarily on texts including the 1675 Discours anatomiques by the Epicurean physician Guillaume Lamy; the anonymous manuscript from circa 1725 entitled L’Âme Matérielle, which is essentially a compendium of texts from the later seventeenth century (Malebranche, Bayle) along with excerpts from Lucretius; and materialist writings such Julien Offray de La Mettrie’s L’Homme-Machine (1748), in order to articulate this concept of a ‘material soul’ with its implications for notions of embodiment, materialism and selfhood

Anhydrobiosis and Freezing-Tolerance:Adaptations That Facilitate the Establishment of Panagrolaimus Nematodes in Polar Habitats

<div><p>Anhydrobiotic animals can survive the loss of both free and bound water from their cells. While in this state they are also resistant to freezing. This physiology adapts anhydrobiotes to harsh environments and it aids their dispersal. <i>Panagrolaimus davidi</i>, a bacterial feeding anhydrobiotic nematode isolated from Ross Island Antarctica, can survive intracellular ice formation when fully hydrated. A capacity to survive freezing while fully hydrated has also been observed in some other Antarctic nematodes. We experimentally determined the anhydrobiotic and freezing-tolerance phenotypes of 24 <i>Panagrolaimus</i> strains from tropical, temperate, continental and polar habitats and we analysed their phylogenetic relationships. We found that several other <i>Panagrolaimus</i> isolates can also survive freezing when fully hydrated and that tissue extracts from these freezing-tolerant nematodes can inhibit the growth of ice crystals. We show that <i>P. davidi</i> belongs to a clade of anhydrobiotic and freezing-tolerant panagrolaimids containing strains from temperate and continental regions and that <i>P. superbus</i>, an early colonizer at Surtsey island, Iceland after its volcanic formation, is closely related to a species from Pennsylvania, USA. Ancestral state reconstructions show that anhydrobiosis evolved deep in the phylogeny of <i>Panagrolaimus</i>. The early-diverging <i>Panagrolaimus</i> lineages are strongly anhydrobiotic but weakly freezing-tolerant, suggesting that freezing tolerance is most likely a derived trait. The common ancestors of the <i>davidi</i> and the <i>superbus</i> clades were anhydrobiotic and also possessed robust freezing tolerance, along with a capacity to inhibit the growth and recrystallization of ice crystals. Unlike other endemic Antarctic nematodes, the life history traits of <i>P. davidi</i> do not show evidence of an evolved response to polar conditions. Thus we suggest that the colonization of Antarctica by <i>P. davidi</i> and of Surtsey by <i>P. superbus</i> may be examples of recent “ecological fitting” of freezing-tolerant anhydrobiotic propagules to the respective abiotic conditions in Ross Island and Surtsey.</p></div

Spinster Homolog 2 (Spns2) Deficiency Causes Early Onset Progressive Hearing Loss

Spinster homolog 2 (Spns2) acts as a Sphingosine-1-phosphate (S1P) transporter in zebrafish and mice, regulating heart development and lymphocyte trafficking respectively. S1P is a biologically active lysophospholipid with multiple roles in signalling. The mechanism of action of Spns2 is still elusive in mammals. Here, we report that Spns2-deficient mice rapidly lost auditory sensitivity and endocochlear potential (EP) from 2 to 3 weeks old. We found progressive degeneration of sensory hair cells in the organ of Corti, but the earliest defect was a decline in the EP, suggesting that dysfunction of the lateral wall was the primary lesion. In the lateral wall of adult mutants, we observed structural changes of marginal cell boundaries and of strial capillaries, and reduced expression of several key proteins involved in the generation of the EP (Kcnj10, Kcnq1, Gjb2 and Gjb6), but these changes were likely to be secondary. Permeability of the boundaries of the stria vascularis and of the strial capillaries appeared normal. We also found focal retinal degeneration and anomalies of retinal capillaries together with anterior eye defects in Spns2 mutant mice. Targeted inactivation of Spns2 in red blood cells, platelets, or lymphatic or vascular endothelial cells did not affect hearing, but targeted ablation of Spns2 in the cochlea using a Sox10-Cre allele produced a similar auditory phenotype to the original mutation, suggesting that local Spns2 expression is critical for hearing in mammals. These findings indicate that Spns2 is required for normal maintenance of the EP and hence for normal auditory function, and support a role for S1P signalling in hearing

In search of self-awareness: Results of the National Lipid Association 2010 Lipid Pulse Membership Survey

In 2010 a survey of the National Lipid Association (NLA) membership was developed and launched with the objective of exploring the demographics, practice patterns, and educational needs of the health professionals in our organization involved in the practice of clinical lipidology. To report the results of this survey and use this information to enable the organization to better serve the needs of our membership. A 30-question survey was administered to the NLA membership before and shortly after the Annual Scientific Sessions in May, 2010. Demographic information, test ordering patterns, educational needs and resources, and technology awareness of 640 valid respondents was assessed. The respondents represent a balanced mix of practitioners in rural and metropolitan population centers throughout the United States. Physicians represent 67%, nurse practitioners and physician assistants 16%, and pharmacists 8% of the respondents. Among physicians, 50% are internal medicine or family medicine specialists, 32% cardiologists, and 11% endocrinologists. Most working in lipid clinics reported that their clinic was financially solvent. The respondents believed that adjunctive lipoprotein testing was clinically useful in risk prediction. The greatest educational needs included statin intolerance; strategies for improving compliance; metabolic syndrome; and lipoprotein particle and apolipoprotein B concentration. The most important sources of lipid information were the Journal of Clinical Lipidology and the NLA Annual Scientific Sessions. The survey provided valuable information that may be used to better serve the practice and educational needs of the membership of the NLA