2,634 research outputs found
Activity Patterns, Home Range, and Microhabitat Selection of a Terrestrial Turtle (Rhinoclemmys rubida perixantha) in a Tropical Dry Forest
Turtles are in trouble worldwide, with nearly half recognized by the International Union for Conservation of Nature (IUCN) as needing special protection. The Eurasian pond and Neotropical wood turtles of the family Geoemydidae are the most diverse turtles and comprise ¼ of all turtle species yet basic information on their natural history is lacking. Moreover, seasonal tropical dry forest (SDTF), where many geoemydids exist, is considered the most endangered ecosystem in the world. We investigated the activity patterns, home range size, and microhabitat selection of the Mexican Spotted Wood Turtle (Rhinoclemmys rubida perixantha) in its SDTF habitat by tracking turtles with trail spools and radio telemetry. Our data show activity of R. r. perixantha was strongly associated with the intense dry season in the tropical deciduous forest, where turtles made fewer movements and walked significantly shorter distances (wet=46.8±3.6m, dry=21.4± 4m, P2=48.5, PThis was the first field study ever conducted on the endangered Mexican Spotted Wood Turtle in its native habitat
Causation, Measurement Relevance and No-conspiracy in EPR
In this paper I assess the adequacy of no-conspiracy conditions employed in
the usual derivations of the Bell inequality in the context of EPR
correlations. First, I look at the EPR correlations from a purely
phenomenological point of view and claim that common cause explanations of
these cannot be ruled out. I argue that an appropriate common cause explanation
requires that no-conspiracy conditions are re-interpreted as mere common
cause-measurement independence conditions. In the right circumstances then,
violations of measurement independence need not entail any kind of conspiracy
(nor backwards in time causation). To the contrary, if measurement operations
in the EPR context are taken to be causally relevant in a specific way to the
experiment outcomes, their explicit causal role provides the grounds for a
common cause explanation of the corresponding correlations.Comment: 20 pages, 1 figur
Applying causality principles to the axiomatization of probabilistic cellular automata
Cellular automata (CA) consist of an array of identical cells, each of which
may take one of a finite number of possible states. The entire array evolves in
discrete time steps by iterating a global evolution G. Further, this global
evolution G is required to be shift-invariant (it acts the same everywhere) and
causal (information cannot be transmitted faster than some fixed number of
cells per time step). At least in the classical, reversible and quantum cases,
these two top-down axiomatic conditions are sufficient to entail more
bottom-up, operational descriptions of G. We investigate whether the same is
true in the probabilistic case. Keywords: Characterization, noise, Markov
process, stochastic Einstein locality, screening-off, common cause principle,
non-signalling, Multi-party non-local box.Comment: 13 pages, 6 figures, LaTeX, v2: refs adde
The Integrated Catchments model of Phosphorus dynamics (INCA-P), a new approach for multiple source assessment in heterogeneous river systems: model structure and equations
International audienceA new model has been developed for assessing the effects of multiple sources of phosphorus on the water quality and aquatic ecology in heterogeneous river systems. The Integrated Catchments model for Phosphorus (INCA-P) is a process-based, mass balance model that simulates the phosphorus dynamics in both the plant/soil system and the stream. The model simulates the spatial variations in phosphorus export from different land use types within a river system using a semi-distributed representation, thereby accounting for the impacts of different land management practices, such as organic and inorganic fertiliser and wastewater applications. The land phase of INCA-P includes a simplified representation of direct runoff, soilwater and groundwater flows, and the soil processes that involve phosphorus. In addition, the model includes a multi-reach in-stream component that routes water down the main river channel. It simulates Organic and Inorganic Phosphorus concentrations in the land phase, and Total Phosphorus (dissolved plus particulate phosphorus) concentrations in the in-stream phase. In-stream Soluble Reactive Phosphorus concentrations are determined from the Total Phosphorus concentrations and the macrophyte, epiphyte and algal biomasses are simulated also. This paper describes the model structure and equations, the limitations and the potential utility of the approach. Keywords: modelling, water quality, phosphorus, soluble reactive phosphorus, basin management</p
A topos for algebraic quantum theory
The aim of this paper is to relate algebraic quantum mechanics to topos
theory, so as to construct new foundations for quantum logic and quantum
spaces. Motivated by Bohr's idea that the empirical content of quantum physics
is accessible only through classical physics, we show how a C*-algebra of
observables A induces a topos T(A) in which the amalgamation of all of its
commutative subalgebras comprises a single commutative C*-algebra. According to
the constructive Gelfand duality theorem of Banaschewski and Mulvey, the latter
has an internal spectrum S(A) in T(A), which in our approach plays the role of
a quantum phase space of the system. Thus we associate a locale (which is the
topos-theoretical notion of a space and which intrinsically carries the
intuitionistic logical structure of a Heyting algebra) to a C*-algebra (which
is the noncommutative notion of a space). In this setting, states on A become
probability measures (more precisely, valuations) on S(A), and self-adjoint
elements of A define continuous functions (more precisely, locale maps) from
S(A) to Scott's interval domain. Noting that open subsets of S(A) correspond to
propositions about the system, the pairing map that assigns a (generalized)
truth value to a state and a proposition assumes an extremely simple
categorical form. Formulated in this way, the quantum theory defined by A is
essentially turned into a classical theory, internal to the topos T(A).Comment: 52 pages, final version, to appear in Communications in Mathematical
Physic
The Oxford Questions on the foundations of quantum physics
The twentieth century saw two fundamental revolutions in physics --
relativity and quantum. Daily use of these theories can numb the sense of
wonder at their immense empirical success. Does their instrumental
effectiveness stand on the rock of secure concepts or the sand of unresolved
fundamentals? Does measuring a quantum system probe, or even create, reality,
or merely change belief? Must relativity and quantum theory just co-exist or
might we find a new theory which unifies the two? To bring such questions into
sharper focus, we convened a conference on Quantum Physics and the Nature of
Reality. Some issues remain as controversial as ever, but some are being nudged
by theory's secret weapon of experiment.Comment: 8 page
Studies on the vascular cambium
The nature of the vascular cambium is discussed and the length of the elements in the secondary xylem related to the division and elongation cycles of the cambial fusiform initials. Particular attention is given to the activities of the storeyed cambium. The ontogeny of the storeyed cambium is described for Hoheria angustifolia Raoul. (Malvaceae). The transition from procambium to cambium was found to take place gradually, the meristem acquiring cambial characteristics over a number of internodes, some before and some after internodal elongation had ceased. The cambium is non storeyed at the commencement of secondary growth but later develops a storeyed pattern. Developmental changes in the cambium with radial growth were studied in Aeschynomene hispida Willd. (Papilionaceae). Repeated radial longitudinal divisions in the fusiform cambial initials in this plant produce a highly developed storeyed pattern with radial growth. The frequency of these divisions decreases with increasing distance from the stem centre. The mean length of the fusiform initials decreases slightly with radial growth. Variation in the size of the fusiform initials and vessel members was also investigated in Hoberia angustifolia. Mean length of the fusiform initials was found to remain constant with increasing distance from the stem centre but a slight decrease was observed with increasing height in the tree. Mean fusiform initial width showed an increase followed by a decrease with increasing height in the tree. The significance of these results is related to the division pattern in the storeyed cambium
Hydrogen limitation and syntrophic growth among natural assemblages of thermophilic methanogens at deep-sea hydrothermal vents
© The Author(s), 2016. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Frontiers in Microbiology 7 (2016): 1240, doi:10.3389/fmicb.2016.01240.Thermophilic methanogens are common autotrophs at hydrothermal vents, but their growth constraints and dependence on H2 syntrophy in situ are poorly understood. Between 2012 and 2015, methanogens and H2-producing heterotrophs were detected by growth at 80∘C and 55∘C at most diffuse (7–40∘C) hydrothermal vent sites at Axial Seamount. Microcosm incubations of diffuse hydrothermal fluids at 80∘C and 55∘C demonstrated that growth of thermophilic and hyperthermophilic methanogens is primarily limited by H2 availability. Amendment of microcosms with NH4+ generally had no effect on CH4 production. However, annual variations in abundance and CH4 production were observed in relation to the eruption cycle of the seamount. Microcosm incubations of hydrothermal fluids at 80∘C and 55∘C supplemented with tryptone and no added H2 showed CH4 production indicating the capacity in situ for methanogenic H2 syntrophy. 16S rRNA genes were found in 80∘C microcosms from H2-producing archaea and H2-consuming methanogens, but not for any bacteria. In 55∘C microcosms, sequences were found from H2-producing bacteria and H2-consuming methanogens and sulfate-reducing bacteria. A co-culture of representative organisms showed that Thermococcus paralvinellae supported the syntrophic growth of Methanocaldococcus bathoardescens at 82∘C and Methanothermococcus sp. strain BW11 at 60∘C. The results demonstrate that modeling of subseafloor methanogenesis should focus primarily on H2 availability and temperature, and that thermophilic H2 syntrophy can support methanogenesis within natural microbial assemblages and may be an important energy source for thermophilic autotrophs in marine geothermal environments.This work was funded by the Gordon and Betty Moore Foundation grant GBMF 3297, the NASA Earth and Space Science Fellowship Program grant NNX11AP78H, the National Science Foundation grant OCE-1547004, with funding from NOAA/PMEL, contribution #4493, and JISAO under NOAA Cooperative Agreement NA15OAR4320063, contribution #2706
Morphine-6-Sulfate Analogues and Their Use for the Treatment of Pain
3-O-Acetylmorphine-6-sulfate analogues are potent, centrally-acting morphine derivatives. The compounds are useful for the treatment of pain
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