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Search Results: 1 - 10 of 6647 matches for " Philip Heraud "
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Phenotypic Plasticity of Southern Ocean Diatoms: Key to Success in the Sea Ice Habitat?
Olivia Sackett, Katherina Petrou, Brian Reedy, Adrian De Grazia, Ross Hill, Martina Doblin, John Beardall, Peter Ralph, Philip Heraud
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0081185
Abstract: Diatoms are the primary source of nutrition and energy for the Southern Ocean ecosystem. Microalgae, including diatoms, synthesise biological macromolecules such as lipids, proteins and carbohydrates for growth, reproduction and acclimation to prevailing environmental conditions. Here we show that three key species of Southern Ocean diatom (Fragilariopsis cylindrus, Chaetoceros simplex and Pseudo-nitzschia subcurvata) exhibited phenotypic plasticity in response to salinity and temperature regimes experienced during the seasonal formation and decay of sea ice. The degree of phenotypic plasticity, in terms of changes in macromolecular composition, was highly species-specific and consistent with each species’ known distribution and abundance throughout sea ice, meltwater and pelagic habitats, suggesting that phenotypic plasticity may have been selected for by the extreme variability of the polar marine environment. We argue that changes in diatom macromolecular composition and shifts in species dominance in response to a changing climate have the potential to alter nutrient and energy fluxes throughout the Southern Ocean ecosystem.
The Characterisation of Pluripotent and Multipotent Stem Cells Using Fourier Transform Infrared Microspectroscopy
Julie Cao,Elizabeth S. Ng,Donald McNaughton,Edouard G. Stanley,Andrew G. Elefanty,Mark J. Tobin,Philip Heraud
International Journal of Molecular Sciences , 2013, DOI: 10.3390/ijms140917453
Abstract: Fourier transform infrared (FTIR) microspectroscopy shows potential as a benign, objective and rapid tool to screen pluripotent and multipotent stem cells for clinical use. It offers a new experimental approach that provides a holistic measurement of macromolecular composition such that a signature representing the internal cellular phenotype is obtained. The use of this technique therefore contributes information that is complementary to that acquired by conventional genetic and immunohistochemical methods.
A Formalization of Polytime Functions
Sylvain Heraud,David Nowak
Computer Science , 2011,
Abstract: We present a deep embedding of Bellantoni and Cook's syntactic characterization of polytime functions. We prove formally that it is correct and complete with respect to the original characterization by Cobham that required a bound to be proved manually. Compared to the paper proof by Bellantoni and Cook, we have been careful in making our proof fully contructive so that we obtain more precise bounding polynomials and more efficient translations between the two characterizations. Another difference is that we consider functions on bitstrings instead of functions on positive integers. This latter change is motivated by the application of our formalization in the context of formal security proofs in cryptography. Based on our core formalization, we have started developing a library of polytime functions that can be reused to build more complex ones.
Human Amnion Epithelial Cells Induced to Express Functional Cystic Fibrosis Transmembrane Conductance Regulator
Sean V. Murphy, Rebecca Lim, Philip Heraud, Marian Cholewa, Mark Le Gros, Martin D. de Jonge, Daryl L. Howard, David Paterson, Courtney McDonald, Anthony Atala, Graham Jenkin, Euan M. Wallace
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0046533
Abstract: Cystic fibrosis, an autosomal recessive disorder caused by a mutation in a gene encoding the cystic fibrosis transmembrane conductance regulator (CFTR), remains a leading cause of childhood respiratory morbidity and mortality. The respiratory consequences of cystic fibrosis include the generation of thick, tenacious mucus that impairs lung clearance, predisposing the individual to repeated and persistent infections, progressive lung damage and shortened lifespan. Currently there is no cure for cystic fibrosis. With this in mind, we investigated the ability of human amnion epithelial cells (hAECs) to express functional CFTR. We found that hAECs formed 3-dimensional structures and expressed the CFTR gene and protein after culture in Small Airway Growth Medium (SAGM). We also observed a polarized CFTR distribution on the membrane of hAECs cultured in SAGM, similar to that observed in polarized airway cells in vivo. Further, hAECs induced to express CFTR possessed functional iodide/chloride (I?/Cl?) ion channels that were inhibited by the CFTR-inhibitor CFTR-172, indicating the presence of functional CFTR ion channels. These data suggest that hAECs may be a promising source for the development of a cellular therapy for cystic fibrosis.
Co-seismic luminescence in Lima, 150 km from the epicenter of the Pisco, Peru earthquake of 15 August 2007
J. A. Heraud,J. A. Lira
Natural Hazards and Earth System Sciences (NHESS) & Discussions (NHESSD) , 2011, DOI: 10.5194/nhess-11-1025-2011
Abstract: The first photographs of Co-seismic Luminescence, commonly known as Earthquake lights (EQLs), were reported in 1968 in Japan. However, there have been documented reports of luminescence associated with earthquakes since ancient times in different parts of the world. Besides this, there is modern scientific work dealing with evidence of and models for the production of such lights. During the Peru 15 August 2007 Mw=8.0 earthquake which occurred at 06:40 p.m. LT, hence dark in the southern wintertime, several EQLs were observed along the Peruvian coast and extensively reported in the capital city of Lima, about 150 km northwest of the epicenter. These lights were video-recorded by a security camera installed at the Pontificia Universidad Catolica del Peru (PUCP) campus and time-correlated with seismic ground accelerations registered at the seismological station on campus, analyzed and related to highly qualified eyewitness observations of the phenomena from other parts of the city and to other video recordings. We believe the evidence presented here contributes significantly to sustain the hypothesis that electromagnetic phenomena related to seismic activity can occur, at least during an earthquake. It is highly probable that continued research in luminescence and the use of magnetometers in studying electromagnetic activity and radon gas emanation detectors will contribute even more towards determining their occurrence during and probably prior to seismic activity.
Pre-earthquake Magnetic Pulses
John Scoville,Jorge Heraud,Friedemann Freund
Physics , 2014,
Abstract: A semiconductor model of rocks is shown to describe unipolar magnetic pulses, a phenomenon that has been observed prior to earthquakes. These pulses are observable because their extremely long wavelength allows them to pass through the Earth's crust. Interestingly, the source of these pulses may be triangulated to pinpoint locations where stress is building deep within the crust. We couple a semiconductor drift-diffusion model to a magnetic field in order to describe the electromagnetic effects associated with electrical currents flowing within rocks. The resulting system of equations is solved numerically and it is seen that a volume of rock may act as a diode that produces transient currents when it switches bias. These unidirectional currents are expected to produce transient unipolar magnetic pulses similar in form, amplitude, and duration to those observed before earthquakes, and this suggests that the pulses could be the result of geophysical semiconductor processes.
Reducing consumption to avert catastrophic global climate change: The case of aviation  [PDF]
Philip Cafaro
Natural Science (NS) , 2013, DOI: 10.4236/ns.2013.51A016
Abstract:

Avoiding potentially catastrophic global climate change is a moral imperative, demanding significant reductions in greenhouse gas emissions from all important transport sectors, including aviation. However, because passenger flights and freight traffic are increasing much faster than efficiency improvements, the aviation sector will not be able to reduce emissions, or even stabilize them at current levels, without direct, forceful action to reduce demand. This paper reviews the ethical principles and empirical realities supporting the case for reducing worldwide aviation traffic. It argues that most passenger air travel and air freight shipping represents unnecessary luxury consumption, which responsible moral agents should willingly reduce in order to mitigate global climate change. It considers several mechanisms for doing so, and contends that they may succeed, but only if combined with an explicit recognition and binding commitment that for the foreseeable future, aviation must be a slow-growth or no-growth sector of the world economy.

Linking Regional Science and Urban Economics: Long-Run Interactions among Preferences for Amenities and Public Goods  [PDF]
Philip E. Philip E. Graves
Modern Economy (ME) , 2012, DOI: 10.4236/me.2012.33035
Abstract: The linked nature of long-term patterns of urban deconcentration and regional change (from rustbelt to sunbelt in the U.S., but with similar phenomena increasingly world-wide) is analyzed in a framework that emphasizes heterogeneous human preferences. The focus is on the important interactions that exist between local and regional amenities, whether exogenous or endogenous. The central thesis is that persistent exogenous amenity variation among regions provides an underlying pattern of regional growth and decline. However, inappropriate provision of local public goods in central cities is seen to lead both to non-optimally large levels of suburbanization and to rates of regional change that are also non-optimally large.
The Pulse Azimuth effect as seen in induction coil magnetometers located in California and Peru 2007–2010, and its possible association with earthquakes
J. C. Dunson,T. E. Bleier,S. Roth,J. Heraud
Natural Hazards and Earth System Sciences (NHESS) & Discussions (NHESSD) , 2011, DOI: 10.5194/nhess-11-2085-2011
Abstract: The QuakeFinder network of magnetometers has recorded geomagnetic field activity in California since 2000. Established as an effort to follow up observations of ULF activity reported from before and after the M = 7.1 Loma Prieta earthquake in 1989 by Stanford University, the QuakeFinder network has over 50 sites, fifteen of which are high-resolution QF1005 and QF1007 systems. Pairs of high-resolution sites have also been installed in Peru and Taiwan. Increases in pulse activity preceding nearby seismic events are followed by decreases in activity afterwards in the three cases that are discussed here. In addition, longer term data is shown, revealing a rich signal structure not previously known in QuakeFinder data, or by many other authors who have reported on pre-seismic ULF phenomena. These pulses occur as separate ensembles, with demonstrable repeatability and uniqueness across a number of properties such as waveform, angle of arrival, amplitude, and duration. Yet they appear to arrive with exponentially distributed inter-arrival times, which indicates a Poisson process rather than a periodic, i.e., stationary process. These pulses were observed using three-axis induction coil magnetometers that are buried 1–2 m under the surface of the Earth. Our sites use a Nyquist frequency of 16 Hertz (25 Hertz for the new QF1007 units), and they record these pulses at amplitudes from 0.1 to 20 nano-Tesla with durations of 0.1 to 12 s. They are predominantly unipolar pulses, which may imply charge migration, and they are stronger in the two horizontal (north-south and east-west) channels than they are in the vertical channels. Pulses have been seen to occur in bursts lasting many hours. The pulses have large amplitudes and study of the three-axis data shows that the amplitude ratios of the pulses taken from pairs of orthogonal coils is stable across the bursts, suggesting a similar source. This paper presents three instances of increases in pulse activity in the 30 days prior to an earthquake, which are each followed by steep declines after the event. The pulses are shown, methods of detecting the pulses and calculating their azimuths is developed and discussed, and then the paper is closed with a brief look at future work.
Cortical Implication in Lower Voluntary Muscle Force Production in Non-Hypoxemic COPD Patients
Francois Alexandre, Nelly Heraud, Nicolas Oliver, Alain Varray
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0100961
Abstract: Recent studies have shown that muscle alterations cannot totally explain peripheral muscle weakness in COPD. Cerebral abnormalities in COPD are well documented but have never been implicated in muscle torque production. The purpose of this study was to assess the neural correlates of quadriceps torque control in COPD patients. Fifteen patients (FEV1 54.1±3.6% predicted) and 15 age- and sex-matched healthy controls performed maximal (MVCs) and submaximal (SVCs) voluntary contractions at 10, 30 and 50% of the maximal voluntary torque of the knee extensors. Neural activity was quantified with changes in functional near-infrared spectroscopy oxyhemoglobin (fNIRS-HbO) over the contralateral primary motor (M1), primary somatosensory (S1), premotor (PMC) and prefrontal (PFC) cortical areas. In parallel to the lower muscle torque, the COPD patients showed lower increase in HbO than healthy controls over the M1 (p<0.05), PMC (p<0.05) and PFC areas (p<0.01) during MVCs. In addition, they exhibited lower HbO changes over the M1 (p<0.01), S1 (p<0.05) and PMC (p<0.01) areas during SVCs at 50% of maximal torque and altered motor control characterized by higher torque fluctuations around the target. The results show that low muscle force production is found in a context of reduced motor cortex activity, which is consistent with central nervous system involvement in COPD muscle weakness.
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