438 research outputs found
Assessment of Demographic, Anthropometric, and Physical Performance Variables as Predictors of Spring Cycling Power
Please download pdf version here
Functional Organization of Locomotor Interneurons in the Ventral Lumbar Spinal Cord of the Newborn Rat
Although the mammalian locomotor CPG has been localized to the lumbar spinal cord, the functional-anatomical organization of flexor and extensor interneurons has not been characterized. Here, we tested the hypothesis that flexor and extensor interneuronal networks for walking are physically segregated in the lumbar spinal cord. For this purpose, we performed optical recordings and lesion experiments from a horizontally sectioned lumbar spinal cord isolated from neonate rats. This ventral hemi spinal cord preparation produces well-organized fictive locomotion when superfused with 5-HT/NMDA. The dorsal surface of the preparation was visualized using the Ca2+ indicator fluo-4 AM, while simultaneously monitoring motor output at ventral roots L2 and L5. Using calcium imaging, we provided a general mapping view of the interneurons that maintained a stable phase relationship with motor output. We showed that the dorsal surface of L1 segment contains a higher density of locomotor rhythmic cells than the other segments. Moreover, L1 segment lesioning induced the most important changes in the locomotor activity in comparison with lesions at the T13 or L2 segments. However, no lesions led to selective disruption of either flexor or extensor output. In addition, this study found no evidence of functional parcellation of locomotor interneurons into flexor and extensor pools at the dorsal-ventral midline of the lumbar spinal cord of the rat
Multi-scale correlations in different futures markets
In the present work we investigate the multiscale nature of the correlations
for high frequency data (1 minute) in different futures markets over a period
of two years, starting on the 1st of January 2003 and ending on the 31st of
December 2004. In particular, by using the concept of "local" Hurst exponent,
we point out how the behaviour of this parameter, usually considered as a
benchmark for persistency/antipersistency recognition in time series, is
largely time-scale dependent in the market context. These findings are a direct
consequence of the intrinsic complexity of a system where trading strategies
are scale-adaptive. Moreover, our analysis points out different regimes in the
dynamical behaviour of the market indices under consideration.Comment: 14 pages and 25 figure
Asymmetry of wind waves studied in a laboratory tank
International audienceAsymmetry of wind waves was studied in laboratory tank tinder varied wind and fetch conditions using both bispectral analysis of wave records and third-order statistics of the surface elevation. It is found skewness S (the normalized third-order moment of surface elevation describing the horizontal asymmetry waves) varies only slightly with the inverse wave u*/Cm (where u* is the air friction velocity and Cm is phase speed of the dominant waves). At the same time asymmetry A, which is determined from the Hilbert transform of the wave record and characterizes the skewness of the rate of change of surface elevation, increase consistently in magnitude with the ratio u*/Cm. This suggests that nonlinear distortion of the wave profile determined by the degree of wind forcing and is a sensitive indicator of wind-wave interaction processes. It is shown that the asymmetric profile of waves can described within the frameworks of the nonlinear nonspectral concept (Plate, 1972; Lake and Yuen, 197 according to which the wind-wave field can be represented as a coherent bound-wave system consisting mainly of dominant component w. and its harmonics propagating with the same speed C. , as observed by Ramamonjiaris and Coantic (1976). The phase shift between o). harmonics is found and shown to increase with the asymmetry of the waves
Managing 100 Digital Humanities Projects: Digital scholarship and archiving in King’s Digital Lab.
During the 2016–2017 financial year, King's Digital Lab (King's College London) undertook an extensive archiving and sustainability project to ensure the ongoing management, security, and sustainability of ~100 digital humanities projects, produced over a twenty-year period. Many of these projects, including seminal publications such as Aphrodisias in Late Antiquity, Inscriptions of Roman Tripolitania, Henry III Fine Rolls, Jonathan Swift Archive, Jane Austen Manuscripts, The Gascon Rolls, The Gough Map, and Inquisitions Post Mortem, occupy important positions in the history of digital humanities. Of the projects inherited by the lab, about half are either of exceptionally high quality or seminal in other ways but almost all of them struggled with funding and technical issues that threatened their survival. By taking a holistic approach to infrastructure, and software engineering and maintenance, the lab has resolved the majority of the issues and secured the short to medium term future of the projects in its care. This article details the conceptual, procedural, and technical approaches used to achieve that, and offers policy recommendations to prevent repetition of the situation in the future
Essential versus accessory aspects of cell death: recommendations of the NCCD 2015
Cells exposed to extreme physicochemical or mechanical stimuli die in an uncontrollable manner, as a result of their immediate structural breakdown. Such an unavoidable variant of cellular demise is generally referred to as ‘accidental cell death’ (ACD). In most settings, however, cell death is initiated by a genetically encoded apparatus, correlating with the fact that its course can be altered by pharmacologic or genetic interventions. ‘Regulated cell death’ (RCD) can occur as part of physiologic programs or can be activated once adaptive responses to perturbations of the extracellular or intracellular microenvironment fail. The biochemical phenomena that accompany RCD may be harnessed to classify it into a few subtypes, which often (but not always) exhibit stereotyped morphologic features. Nonetheless, efficiently inhibiting the processes that are commonly thought to cause RCD, such as the activation of executioner caspases in the course of apoptosis, does not exert true cytoprotective effects in the mammalian system, but simply alters the kinetics of cellular demise as it shifts its morphologic and biochemical correlates. Conversely, bona fide cytoprotection can be achieved by inhibiting the transduction of lethal signals in the early phases of the process, when adaptive responses are still operational. Thus, the mechanisms that truly execute RCD may be less understood, less inhibitable and perhaps more homogeneous than previously thought. Here, the Nomenclature Committee on Cell Death formulates a set of recommendations to help scientists and researchers to discriminate between essential and accessory aspects of cell death
Recommended from our members
F.J. Turner’s ‘frontier thesis’: the ruse of American ‘character'
American society was transformed by the expansion of capital Westward and the explosion in opportunities that ensued for land grabbing and agricultural and industrial investment. In Turner’s (1961) frontier thesis this was portrayed as resulting in the emergence of ‘the new man’ i.e. the fulfilment of American character. The frontier thesis is a neo-Darwinian contribution. It posits exceptionalism and transcendence as the keys to American character. The gene pool of the Americans, thriving in a new geographical and social environment, is depicted as achieving a higher level of development than the stratified societies of Old Europe. What the thesis ignores is the importance of orthodox Eurocentric strategies of colonization and land appropriation. Turner portrays pioneer/settler society as a heroic departure, but in many ways, it is a continuation of European precedents. Analogously, the proposition that the push West crystallized American character obscures the role of personality, especially in urban-industrial settings, in establishing the parameters of American life. Turner conceived of character as emerging from a struggle with the spatial frontier. But the struggles of personality with the social frontier of repression and establishment values is no less significant. The paper examines the tensions between character and personality by using some ideas developed by Carl Schmitt on the significance of ‘the opportunity’ in competitive advantage. The importance of the opportunity and personality in developing the American way of life are examined by the vaudeville and celebrity traditions. The exploitation of contingency for personal advantage, the use of melodrama to engineer social impact, the social validation of forthright behaviour are examined in the context of the careers of the film actress Mae West and the comedian Bob Hope
Is music enriching for group-housed captive chimpanzees (Pan troglodytes)?
Many facilities that house captive primates play music for animal enrichment or for caregiver enjoyment. However, the impact on primates is unknown as previous studies have been inconclusive. We conducted three studies with zoo-housed chimpanzees (Pan troglodytes) and one with group-housed chimpanzees at the National Centre for Chimpanzee Care to investigate the effects of classical and pop/rock music on various variables that may be indicative of increased welfare. Study one compared the behaviour and use of space of 18 animals when silence, classical or pop/rock music was played into one of several indoor areas. Overall, chimpanzees did not actively avoid the area when music was playing but were more likely to exit the area when songs with higher beats per minute were broadcast. Chimpanzees showed significantly fewer active social behaviours when music, rather than silence, was playing. They also tended to be more active and engage in less abnormal behaviour during the music but there was no change to either self-grooming or aggression between music and silent conditions. The genre of music had no differential effects on the chimpanzees’ use of space and behaviour. In the second study, continuous focal observations were carried out on three individuals with relatively high levels of abnormal behaviour. No differences in behaviour between music and silence periods were found in any of the individuals. The final two studies used devices that allowed chimpanzees to choose if they wanted to listen to music of various types or silence. Both studies showed that there were no persistent preferences for any type of music or silence. When taken together, our results do not suggest music is enriching for group-housed captive chimpanzees, but they also do not suggest that music has a negative effect on welfare
5-Hydroxymethylcytosine is a predominantly stable DNA modification.
5-Hydroxymethylcytosine (hmC) is an oxidation product of 5-methylcytosine which is present in the deoxyribonucleic acid (DNA) of most mammalian cells. Reduction of hmC levels in DNA is a hallmark of cancers. Elucidating the dynamics of this oxidation reaction and the lifetime of hmC in DNA is fundamental to understanding hmC function. Using stable isotope labelling of cytosine derivatives in the DNA of mammalian cells and ultrasensitive tandem liquid-chromatography mass spectrometry, we show that the majority of hmC is a stable modification, as opposed to a transient intermediate. In contrast with DNA methylation, which occurs immediately during replication, hmC forms slowly during the first 30 hours following DNA synthesis. Isotopic labelling of DNA in mouse tissues confirmed the stability of hmC in vivo and demonstrated a relationship between global levels of hmC and cell proliferation. These insights have important implications for understanding the states of chemically modified DNA bases in health and disease.We would like to acknowledge the CRUK CI Flow Cytometry and Histopathology/ISH core facilities for their contributions, David Oxley, Clive d’Santos and Donna Michelle-Smith for their support with mass spectrometry, Xiangang Zou for his help with mES cells and David Tannahill for critical reading of the manuscript. This work was funded by Cancer Research UK (all authors) and the Wellcome Trust Senior Investigator Award (S.B.).This is the accepted manuscript. The final version is available from Nature Chemistry at http://www.nature.com/nchem/journal/vaop/ncurrent/full/nchem.2064.html
- …