3,956 research outputs found
Microrheology with optical tweezers: data analysis
We present a data analysis procedure that provides the solution to a long-standing issue in microrheology studies, i.e. the evaluation of the fluids' linear viscoelastic properties from the analysis of a finite set of experimental data, describing (for instance) the time-dependent mean-square displacement of suspended probe particles experiencing Brownian fluctuations. We report, for the first time in the literature, the linear viscoelastic response of an optically trapped bead suspended in a Newtonian fluid, over the entire range of experimentally accessible frequencies. The general validity of the proposed method makes it transferable to the majority of microrheology and rheology techniques
A special simplex in the state space for entangled qudits
Focus is on two parties with Hilbert spaces of dimension d, i.e. "qudits". In
the state space of these two possibly entangled qudits an analogue to the well
known tetrahedron with the four qubit Bell states at the vertices is presented.
The simplex analogue to this magic tetrahedron includes mixed states. Each of
these states appears to each of the two parties as the maximally mixed state.
Some studies on these states are performed, and special elements of this set
are identified. A large number of them is included in the chosen simplex which
fits exactly into conditions needed for teleportation and other applications.
Its rich symmetry - related to that of a classical phase space - helps to study
entanglement, to construct witnesses and perform partial transpositions. This
simplex has been explored in details for d=3. In this paper the mathematical
background and extensions to arbitrary dimensions are analysed.Comment: 24 pages, in connection with the Workshop 'Theory and Technology in
Quantum Information, Communication, Computation and Cryptography' June 2006,
Trieste; summary and outlook added, minor changes in notatio
Unified analysis of terminal-time control in classical and quantum systems
Many phenomena in physics, chemistry, and biology involve seeking an optimal
control to maximize an objective for a classical or quantum system which is
open and interacting with its environment. The complexity of finding an optimal
control for maximizing an objective is strongly affected by the possible
existence of sub-optimal maxima. Within a unified framework under specified
conditions, control objectives for maximizing at a terminal time physical
observables of open classical and quantum systems are shown to be inherently
free of sub-optimal maxima. This attractive feature is of central importance
for enabling the discovery of controls in a seamless fashion in a wide range of
phenomena transcending the quantum and classical regimes.Comment: 10 page
Transformation Optics for Plasmonics
A new strategy to control the flow of surface plasmon polaritons at metallic
surfaces is presented. It is based on the application of the concept of
Transformation Optics to devise the optical parameters of the dielectric medium
placed on top of the metal surface. We describe the general methodology for the
design of Transformation-Optical devices for surface plasmons and analyze, for
proof-of-principle purposes, three representative examples with different
functionalities: a beam shifter, a cylindrical cloak and a ground-plane cloak.Comment: 15 pages, 3 figure
Molecular and morphometric variation in European populations of the articulate brachiopod <i>Terebeatulina retusa</i>
Molecular and morphometric variation within and between population samples of the articulate brachiopod <i>Terebratulina</i> spp., collected in 1985-1987 from a Norwegian fjord, sea lochs and costal sites in western Scotland, the southern English Channel (Brittany) and the western Mediterranean, were measured by the analysis of variation in the lengths of mitochondrial DNA (mtDNA) fragments produced by digestion with nine restriction endonucleases and by multivariate statistical analysis of six selected morphometric parameters. Nucleotide difference within each population sample was high. Nucleotide difference between population samples from the Scottish sites, both those that are tidally contiguous and those that appear to be geographically isolated, were not significantly different from zero. Nucleotide differences between the populations samples from Norway, Brittany, Scotland and the western Mediterranean were also very low. Morphometric analysis confirmed the absence of substantial differentiation
Herbivores at the Highest Risk of Extinction Among Mammals, Birds, and Reptiles
As a result of their extensive home ranges and slow population growth rates, predators have often been perceived to suffer higher risks of extinction than other trophic groups. Our study challenges this extinction-risk paradigm by quantitatively comparing patterns of extinction risk across different trophic groups of mammals, birds, and reptiles. We found that trophic level and body size were significant factors that influenced extinction risk in all taxa. At multiple spatial and temporal scales, herbivores, especially herbivorous reptiles and large-bodied herbivores, consistently have the highest proportions of threatened species. This observed elevated extinction risk for herbivores is ecologically consequential, given the important roles that herbivores are known to play in controlling ecosystem function
ERβ Binds N-CoR in the Presence of Estrogens via an LXXLL-like Motif in the N-CoR C-terminus
Nuclear receptors (NRs) usually bind the corepressors N-CoR and SMRT in the absence of ligand or in the presence of antagonists. Agonist binding leads to corepressor release and recruitment of coactivators. Here, we report that estrogen receptor β (ERβ) binds N-CoR and SMRT in the presence of agonists, but not antagonists, in vitro and in vivo. This ligand preference differs from that of ERα interactions with corepressors, which are inhibited by estradiol, and resembles that of ERβ interactions with coactivators. ERβ /N-CoR interactions involve ERβ AF-2, which also mediates coactivator recognition. Moreover, ERβ recognizes a sequence (PLTIRML) in the N-CoR C-terminus that resembles coactivator LXXLL motifs. Inhibition of histone deacetylase activity specifically potentiates ERβ LBD activity, suggesting that corepressors restrict the activity of AF-2. We conclude that the ER isoforms show completely distinct modes of interaction with a physiologically important corepressor and discuss our results in terms of ER isoform specificity in vivo
Drug repurposing for rare:progress and opportunities for the rare disease community
Repurposing is one of the key opportunities to address the unmet rare diseases therapeutic need. Based on cases of drug repurposing in small population conditions, and previous work in drug repurposing, we analyzed the most important lessons learned, such as the sharing of clinical observations, reaching out to regulatory scientific advice at an early stage, and public-private collaboration. In addition, current upcoming trends in the field of drug repurposing in rare diseases were analyzed, including the role these trends could play in the rare diseases’ ecosystem. Specifically, we cover the opportunities of innovation platforms, the use of real-world data, the use of artificial intelligence, regulatory initiatives in repurposing, and patient engagement throughout the repurposing project. The outcomes from these emerging activities will help progress the field of drug repurposing for the benefit of patients, public health and medicines development
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