812 research outputs found
ORK1, a potassium-selective leak channel with two pore domains cloned from Drosophila melanogaster by expression in Saccharomyces cerevisiae.
A K+ channel gene has been cloned from Drosophila melanogaster by complementation in Saccharomyces cerevisiae cells defective for K+ uptake. Naturally expressed in the neuromuscular tissues of adult flies, this gene confers K+ transport capacity on yeast cells when heterologously expressed. In Xenopus laevis oocytes, expression yields an ungated K(+)-selective current whose attributes resemble the "leak" conductance thought to mediate the resting potential of vertebrate myelinated neurons but whose molecular nature has long remained elusive. The predicted protein has two pore (P) domains and four membrane-spanning helices and is a member of a newly recognized K+ channel family. Expression of the channel in flies and yeast cells makes feasible studies of structure and in vivo function using genetic approaches that are not possible in higher animals
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Erratum: ORK1, a potassium-selective leak channel with two pore domains cloned from Drosophila melanogaster by expression in Saccharomyces cerevisiae (Proceedings of the National Academy of Sciences of the USA (1996) 93:23 (13256-13261))
Signalling Responses Following Varying Sequencing of Strength and Endurance Training in a Fed State.
The objective of this study was to compare anabolic signalling responses to differing sequences of concurrent strength and endurance training in a fed state.Eighteen resistance-trained males were randomly assigned to the following experimental conditions; i) strength training (ST), ii) strength followed by endurance training (ST-END) or iii) endurance followed by strength training (END-ST). Muscle tissue samples were taken from the vastus lateralis before each exercise protocol, upon cessation of exercise, and 1 h-post cessation of strength training. Tissue was analysed for total and phosphorylated (p-) signalling proteins linked to the mTOR and AMPK networks.Strength training performance was similar between ST, ST-END and END-ST. p-S6k1 was elevated from baseline 1 h post training in ST and ST-END (both p < 0.05). p-4E-BP1 was significantly lower than baseline post ST (p = 0.01), while 1 h post exercise in the ST-END condition p-4E-BP1 was significantly greater than post exercise (p = 0.04). p-ACC was elevated from baseline both post and 1 h post exercise (both p < 0.05) in the END-ST condition. AMPK, mTOR, p38, PKB, eEF2 responded similarly to the ST, ST-END and END-ST. Signalling responses to ST, ST-END and END were largely similar. As such it cannot be ascertained which sequence of concurrent strength and endurance training is most favourable in promoting anabolic signalling.These data indicate that in the case of the present study an acute bout of concurrent training of differing sequences elicited similar responses of the AMPK and mTOR networks
Bell Correlations and the Common Future
Reichenbach's principle states that in a causal structure, correlations of
classical information can stem from a common cause in the common past or a
direct influence from one of the events in correlation to the other. The
difficulty of explaining Bell correlations through a mechanism in that spirit
can be read as questioning either the principle or even its basis: causality.
In the former case, the principle can be replaced by its quantum version,
accepting as a common cause an entangled state, leaving the phenomenon as
mysterious as ever on the classical level (on which, after all, it occurs). If,
more radically, the causal structure is questioned in principle, closed
space-time curves may become possible that, as is argued in the present note,
can give rise to non-local correlations if to-be-correlated pieces of classical
information meet in the common future --- which they need to if the correlation
is to be detected in the first place. The result is a view resembling Brassard
and Raymond-Robichaud's parallel-lives variant of Hermann's and Everett's
relative-state formalism, avoiding "multiple realities."Comment: 8 pages, 5 figure
Using fractional exhaled nitric oxide (FeNO) to diagnose steroid-responsive disease and guide asthma management in routine care
Acknowledgements We thank Robin Taylor for his informative thinking and publications on FeNO, which have helped to influence and direct the thinking of the authors. Funding Extraction of the real-life dataset was funded by Research in Real Life Limited, the analysis of the dataset and the writing of this manuscript were co-funded (50:50) by Research in Real Life Limited and Aerocrine.Peer reviewedPublisher PD
Teaching the history of geography:Current challenges and future directions
Drawing upon the personal reflections of geographical educators in Brazil, Canada, the UK, and the US, this Forum provides a state-of-the-discipline review of teaching in the history of geography; identifies the practical and pedagogical challenges associated with that teaching; and offers suggestions and provocations as to future innovation. The Forum shows how teaching in the history of geography is valued – as a tool of identity making, as a device for cohort building and professionalization, and as a means of interrogating the disciplinary present – but also how it is challenged by neoliberal educational policies, competing priorities in curriculum design, and sub-disciplinary divisions
An ultraviolet-optical flare from the tidal disruption of a helium-rich stellar core
The flare of radiation from the tidal disruption and accretion of a star can
be used as a marker for supermassive black holes that otherwise lie dormant and
undetected in the centres of distant galaxies. Previous candidate flares have
had declining light curves in good agreement with expectations, but with poor
constraints on the time of disruption and the type of star disrupted, because
the rising emission was not observed. Recently, two `relativistic' candidate
tidal disruption events were discovered, each of whose extreme X-ray luminosity
and synchrotron radio emission were interpreted as the onset of emission from a
relativistic jet. Here we report the discovery of a luminous
ultraviolet-optical flare from the nuclear region of an inactive galaxy at a
redshift of 0.1696. The observed continuum is cooler than expected for a simple
accreting debris disk, but the well-sampled rise and decline of its light curve
follows the predicted mass accretion rate, and can be modelled to determine the
time of disruption to an accuracy of two days. The black hole has a mass of
about 2 million solar masses, modulo a factor dependent on the mass and radius
of the star disrupted. On the basis of the spectroscopic signature of ionized
helium from the unbound debris, we determine that the disrupted star was a
helium-rich stellar core.Comment: To appear in Nature on May 10, 201
X-ray spectropolarimetric measurements of the Kerr metric
It is thought that the spacetime geometry around black hole candidates is
described by the Kerr solution, but an observational confirmation is still
missing. Today, the continuum-fitting method and the analysis of the iron
K line cannot unambiguously test the Kerr paradigm because of the
degeneracy among the parameters of the system, in the sense that it is
impossible with current X-ray data to distinguish a Kerr black hole from a
non-Kerr object with different values of the model parameters. In this paper,
we study the possibility of testing the Kerr nature of black hole candidates
with X-ray spectropolarimetric measurements. Within our simplified model that
does not include the effect of returning radiation, we find that it is
impossible to test the Kerr metric and the problem is still the strong
correlation between the spin and possible deviations from the Kerr geometry.
Moreover, the correlation is very similar to that of other two techniques,
which makes the combination of different measurements not very helpful.
Nevertheless, our results cannot be taken as conclusive and, in order to arrive
at a final answer, the effect of returning radiation should be properly taken
into account.Comment: 12 pages, 8 figures. v2: refereed versio
The Human Nasal Microbiota and Staphylococcus aureus Carriage
BACKGROUND: Colonization of humans with Staphylococcus aureus is a critical prerequisite of subsequent clinical infection of the skin, blood, lung, heart and other deep tissues. S. aureus persistently or intermittently colonizes the nares of approximately 50% of healthy adults, whereas approximately 50% of the general population is rarely or never colonized by this pathogen. Because microbial consortia within the nasal cavity may be an important determinant of S. aureus colonization we determined the composition and dynamics of the nasal microbiota and correlated specific microorganisms with S. aureus colonization. METHODOLOGY/PRINCIPAL FINDINGS: Nasal specimens were collected longitudinally from five healthy adults and a cross-section of hospitalized patients (26 S. aureus carriers and 16 non-carriers). Culture-independent analysis of 16S rRNA sequences revealed that the nasal microbiota of healthy subjects consists primarily of members of the phylum Actinobacteria (e.g., Propionibacterium spp. and Corynebacterium spp.), with proportionally less representation of other phyla, including Firmicutes (e.g., Staphylococcus spp.) and Proteobacteria (e.g. Enterobacter spp). In contrast, inpatient nasal microbiotas were enriched in S. aureus or Staphylococcus epidermidis and diminished in several actinobacterial groups, most notably Propionibacterium acnes. Moreover, within the inpatient population S. aureus colonization was negatively correlated with the abundances of several microbial groups, including S. epidermidis (p = 0.004). CONCLUSIONS/SIGNIFICANCE: The nares environment is colonized by a temporally stable microbiota that is distinct from other regions of the integument. Negative association between S. aureus, S. epidermidis, and other groups suggests microbial competition during colonization of the nares, a finding that could be exploited to limit S. aureus colonization
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