19,504 research outputs found
Alternative NAD(P)H dehydrogenase and alternative oxidase: proposed physiological roles in animals
The electron transport systems in mitochondria of many organisms contain alternative respiratory enzymes distinct from those of the canonical respiratory system depicted in textbooks. Two of these enzymes, the alternative NADH dehydrogenase and the alternative oxidase, were of interest to a limited circle of researchers until they were envisioned as gene therapy tools for mitochondrial disease treatment. Recently, these enzymes were discovered in several animals. Here, we analyse the functioning of alternative NADH dehydrogenases and oxidases in different organisms. We propose that both enzymes ensure bioenergetic and metabolic flexibility during environmental transitions or other conditions which may compromise the operation of the canonical respiratory system.
The electron transport systems in mitochondria of many organisms contain alternative respiratory enzymes distinct from those of the canonical respiratory system depicted in textbooks. Two of these enzymes, the alternative NADH dehydrogenase and the alternative oxidase, were of interest to a limited circle of researchers until they were envisioned as gene therapy tools for mitochondrial disease treatment. Recently, these enzymes were discovered in several animals. Here, we analyse the functioning of alternative NADH dehydrogenases and oxidases in different organisms. We propose that both enzymes ensure bioenergetic and metabolic flexibility during environmental transitions or other conditions which may compromise the operation of the canonical respiratory system
Constraining the origin of the planetary debris surrounding ZTF J0139+5245 through rotational fission of a triaxial asteroid
White dwarfs containing orbiting planetesimals or their debris represent crucial benchmarks by which theoretical investigations of post-main-sequence planetary systems may be calibrated. The photometric transit signatures of likely planetary debris in the ZTF J0139+5245 white dwarf system have an orbital period of about 110 d. An asteroid which breaks up to produce this debris may spin itself to destruction through repeated close encounters with the star without entering its Roche radius and without influence from the white dwarf’s luminosity. Here, we place coupled constraints on the orbital pericentre (q) and the ratio (β) of the middle to longest semiaxes of a triaxial asteroid which disrupts outside of this white dwarf’s Roche radius (rRoche) soon after attaining its 110-d orbit. We find that disruption within tens of years is likely when β ≲ 0.6 and q ≈ 1.0–2.0rRoche, and when β ≲ 0.2 out to q ≈ 2.5rRoche. Analysing the longer time-scale disruption of triaxial asteroids around ZTF J0139+5245 is desirable but may require either an analytical approach relying on ergodic theory or novel numerical techniques
Minimally Parametric Power Spectrum Reconstruction from the Lyman-alpha Forest
Current results from the Lyman alpha forest assume that the primordial power
spectrum of density perturbations follows a simple power law form, with
running. We present the first analysis of Lyman alpha data to study the effect
of relaxing this strong assumption on primordial and astrophysical constraints.
We perform a large suite of numerical simulations, using them to calibrate a
minimally parametric framework for describing the power spectrum. Combined with
cross-validation, a statistical technique which prevents over-fitting of the
data, this framework allows us to reconstruct the power spectrum shape without
strong prior assumptions. We find no evidence for deviation from
scale-invariance; our analysis also shows that current Lyman alpha data do not
have sufficient statistical power to robustly probe the shape of the power
spectrum at these scales. In contrast, the ongoing Baryon Oscillation Sky
Survey (BOSS) will be able to do so with high precision. Furthermore, this
near-future data will be able to break degeneracies between the power spectrum
shape and astrophysical parameters.Comment: 11 pages plus appendices, 8 figures. v2: matches version published in
MNRAS. Some clarifications to discussion and exposition, updated reference
2-Server PIR with sub-polynomial communication
A 2-server Private Information Retrieval (PIR) scheme allows a user to
retrieve the th bit of an -bit database replicated among two servers
(which do not communicate) while not revealing any information about to
either server. In this work we construct a 1-round 2-server PIR with total
communication cost . This improves over the
currently known 2-server protocols which require communication and
matches the communication cost of known 3-server PIR schemes. Our improvement
comes from reducing the number of servers in existing protocols, based on
Matching Vector Codes, from 3 or 4 servers to 2. This is achieved by viewing
these protocols in an algebraic way (using polynomial interpolation) and
extending them using partial derivatives
Restorative justice : Transformation Project Prison Ministry\u27s reason for growth and motivation of the volunteers
https://place.asburyseminary.edu/ecommonsatsdissertations/1836/thumbnail.jp
Coreografías
Traducción al castellano del intercambio de correspondencia entre Jacques Derrida y Christie V. McDonald, en el otoño de 1981. A partir de las preguntas de McDonald, el filósofo reflexiona en torno a temas como el género, la diferencia sexual, los movimientos feministas, los feminismos, el lugar de la mujer, y el aporte que una perspectiva como la deconstrucción ofrece a su abordaje
Angular dependent magnetothermopower of alpha-(ET)2KHg(SCN)4
The magnetic field and angular dependencies of the thermopower and Nernst
effect of the quasi-two-dimensional organic conductor alpha-(ET)2KHg(SCN)4 are
experimentally measured at temperatures below (4 K) and above (9 K) the
transition temperature to fields of In addition, a theoretical model which
involves a magnetic breakdown effect between the q1D and q2D bands is proposed
in order to simulate the data. Analysis of the background components of the
thermopower and Nernst effect imply that at low temperatures, in the CDW state,
the properties of alpha-(ET)2KHg(SCN)4 are determined mostly by the orbits on
the new open Fermi sheets. Quantum oscillations observed in the both
thermoelectric effects, at fields above 8 T, originate only from the alpha
orbit.Comment: 25 pages, 18 figure
Helmholtz solitons in optical materials with a dual power-law refractive index
A nonlinear Helmholtz equation is proposed for modelling scalar optical beams in uniform planar waveguides whose refractive index exhibits a purely-focusing dual powerlaw
dependence on the electric field amplitude. Two families of exact analytical solitons, describing forward- and backward-propagating beams, are derived. These solutions are
physically and mathematically distinct from those recently discovered for related nonlinearities. The geometry of the new solitons is examined, conservation laws are reported,
and classic paraxial predictions are recovered in a simultaneous multiple limit. Conventional semi-analytical techniques assist in studying the stability of these nonparaxial solitons, whose propagation properties are investigated through extensive simulations
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