15,949 research outputs found
Reply to "Comment on 'A linear optics implementation of weak values in Hardy's paradox'"
The comment by Lundeen et al. contains two criticisms of our proposal. While
we agree that the state-preparation procedure could be replaced by a simpler
setup as proposed by the authors of the comment, we do not agree with the
authors on their second, and more important point regarding two-particle weak
measurements. We believe this to be the result of a misunderstanding of our
original paper.Comment: 2 pages, accepted in PR
Linear optics implementation of weak values in Hardy's paradox
We propose an experimental setup for the implementation of weak measurements
in the context of the gedankenexperiment known as Hardy's Paradox. As Aharonov
et al. showed, these weak values form a language with which the paradox can be
resolved. Our analysis shows that this language is indeed consistent and
experimentally testable. It also reveals exactly how a combination of weak
values can give rise to an apparently paradoxical result.Comment: 4 pages, accepted by PR
Gravitational waves from an accreting neutron star with a magnetic mountain
We calculate the amplitude of gravitational waves from a neutron star accreting symmetrically at its magnetic poles. The magnetic field, which is compressed into an equatorial belt during accretion, confines accreted matter in a mountain at the magnetic pole, producing gravitational waves. We compute hydromagnetic equilibria and the corresponding quadrupole moment as a function of the accreted mass, Ma, finding the polarization- and orientation- averaged wave strain at Earth to be h_c = 6.3 Ă 10^(â25)(M_a/10^(â5)M_â)(Æ/0.6kHz)^2(d/1kpc)^(â1) for a range of conditions, where Æ is the wave frequency and d is the distance to the source. This is ~ 10^2 times greater than previous estimates, which failed to treat the mass-flux distribution self-consistently with respect to flux-freezin
Cell-free protein synthesizing systems from Vicia faba (L)
Vicia faba (L) seeds form protein as their major food reserve. The two major storage proteins, vicilin and legumin, which account for up to 20% dry weight of the mature seed are formed within a comparatively short period during seed development, and during this period, a significant part of the total metabolism of the cell is directed towards their synthesis. An active cell-free amino acid incorporating system has been isolated from developing seeds, and its conditions of activity determined in in vitro incubations using polyuridylic acid as a messenger. Bacterial contamination of the incubations was low. The activity of this system in amino acid incorporation is compared with other in vitro systems from plants. Microsomes, enzyme fractions and tRNA were prepared from developing seeds of different ages, and the above system-was used to assay changes in the amino acid incorporating activity of components from different ages of seeds, to see if any correlation could be found between the changes in the in vivo protein synthetic activity during seed development with the changes in the in vitro efficiency of the components in incorporation. Rates of in vitro amino acid incorporation were compared with the estimated rate of in vivo synthesis of the storage proteins. The changes in the in vitro amino acid incorporating activity are discussed with reference to the anatomical changes occurring during seed development, as seen in electron micrographs of developing seeds, and in particular with reference to the changes in the free and membrane bound ribosome content. Further evidence for the role of the membrane bound ribosomes in storage protein synthesis is presented
Weak Measurement of the Arrival Times of Single Photons and Pairs of Entangled Photons
In this paper we propose a setup for the weak measurement of photon arrival
time. It is found that the weak values of this arrival time can lie far away
from the expectation value, and in principle also in regions forbidden by
special relativity. We discuss in brief the implications of these results as
well as their reconciliation with the principle of causality. Furthermore, an
analysis of the weak arrival times of a pair of photons in a Bell state shows
that these weak arrival times are correlated.Comment: 4 pages, 1 figur
The accelerating influence of humans on mammalian macroecological patterns over the late Quaternary
The transition of hominins to a largely meat-based diet ~1.8 million years ago led to the exploitation of other mammals for food and resources. As hominins, particularly archaic and modern humans, became increasingly abundant and dispersed across the globe, a temporally and spatially transgressive extinction of large-bodied mammals followed; the degree of selectivity was unprecedented in the Cenozoic fossil record. Today, most remaining large-bodied mammal species are confined to Africa, where they coevolved with hominins. Here, using a comprehensive global dataset of mammal distribution, life history and ecology, we examine the consequences of âbody size downgradingâ of mammals over the late Quaternary on fundamental macroecological patterns. Specifically, we examine changes in species diversity, global and continental body size distributions, allometric scaling of geographic range size with body mass, and the scaling of maximum body size with area. Moreover, we project these patterns toward a potential future scenario in which all mammals currently listed as vulnerable on the IUCN\u27s Red List are extirpated. Our analysis demonstrates that anthropogenic impact on earth systems predates the terminal Pleistocene and has grown as populations increased and humans have become more widespread. Moreover, owing to the disproportionate influence on ecosystem structure and function of megafauna, past and present body size downgrading has reshaped Earth\u27s biosphere. Thus, macroecological studies based only on modern species yield distorted results, which are not representative of the patterns present for most of mammal evolution. Our review supports the concept of benchmarking the âAnthropoceneâ with the earliest activities of Homo sapiens
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