Boson sampling from a Gaussian state Lund, A P; Laing, A; Rahimi-Keshari, S ...
Physical review letters,
09/2014, Volume:
113, Issue:
10
Journal Article
Peer reviewed
Open access
We pose a randomized boson-sampling problem. Strong evidence exists that such a problem becomes intractable on a classical computer as a function of the number of bosons. We describe a quantum ...optical processor that can solve this problem efficiently based on a Gaussian input state, a linear optical network, and nonadaptive photon counting measurements. All the elements required to build such a processor currently exist. The demonstration of such a device would provide empirical evidence that quantum computers can, indeed, outperform classical computers and could lead to applications.
The microRNA (miRNA) miR-10 family has attracted attention because of its conservation and the position of the miR-10 genes within the Hox clusters of developmental regulators. In several species, ...miR-10 is coexpressed with a set of Hox genes and has been found to regulate the translation of Hox transcripts. In addition, members of the miR-10 family are de-regulated in several cancer forms. Aside from acting in translational repression, miR-10 was recently found to bind a group of transcripts containing a terminal oligo-pyrimidine (TOP) motif and to induce their translation, thereby adding a new function to the miRNA repertoire.
Signal amplification is ubiquitous in the control of physical systems, and the ultimate performance limit of amplifiers is set by quantum physics. Increasing the amplitude of an unknown quantum ...optical field, or any harmonic oscillator state, must introduce noise. This linear amplification noise prevents perfect copying of the quantum state, enforces quantum limits on communications and metrology, and is the mechanism preventing the increase of entanglement via local operations. Non-deterministic versions of ideal cloning and local entanglement increase (distillation) are allowed, suggesting the possibility of non-deterministic noiseless linear amplification. Here we introduce, and experimentally demonstrate, such a noiseless linear amplifier for quantum states of the optical field, and use it for distillation of field-mode entanglement. This simple but powerful circuit enables practical devices for enhancing quantum technologies. The idea of noiseless amplification unifies approaches to cloning and distillation, and will find applications in quantum metrology and communications.
A significant proportion of bacteria express two or more chaperonin genes. Chaperonins are a group of molecular chaperones, defined by sequence similarity, required for the folding of some cellular ...proteins. Chaperonin monomers have a mass of c. 60 kDa, and are typically found as large protein complexes containing 14 subunits arranged in two rings. The mechanism of action of the Escherichia coli GroEL protein has been studied in great detail. It acts by binding to unfolded proteins and enabling them to fold in a protected environment where they do not interact with any other proteins. GroEL can assist the folding of many proteins of different sizes, sequences, and structures, and homologues from many different bacteria can functionally replace GroEL in E. coli. What then are the functions of multiple chaperonins? Do they provide a mechanism for cells to increase their general chaperoning ability, or have they become specialized to take on specific novel cellular roles? Here I will review the genetic, biochemical, and phylogenetic evidence that has a bearing on this question, and show that there is good evidence for at least some specificity of function in multiple chaperonin genes.
Abstract
Merging neutron stars produce “kilonovae”—electromagnetic transients powered by the decay of unstable nuclei synthesized via rapid neutron capture (the
r
-process) in material that is ...gravitationally unbound during inspiral and coalescence. Kilonova emission, if accurately interpreted, can be used to characterize the masses and compositions of merger-driven outflows, helping to resolve a long-standing debate about the origins of
r
-process material in the Universe. We explore how the uncertain properties of nuclei involved in the
r
-process complicate the inference of outflow properties from kilonova observations. Using
r
-process simulations, we show how nuclear physics uncertainties impact predictions of radioactive heating and element synthesis. For a set of models that span a large range in both predicted heating and final abundances, we carry out detailed numerical calculations of decay product thermalization and radiation transport in a kilonova ejecta with a fixed mass and density profile. The light curves associated with our models exhibit great diversity in their luminosities, with peak brightness varying by more than an order of magnitude. We also find variability in the shape of the kilonova light curves and their color, which in some cases runs counter to the expectation that increasing levels of lanthanide and/or actinide enrichment will be correlated with longer, dimmer, redder emission.
The genus Mitragyna (Rubiacaeae) has been traditionally used in parts of Africa, Asia and Oceania. In recent years, there has been increased interest in species of Mitragyna with the introduction of ...products to western markets and regulatory uncertainty.
This paper reviewed the traditional ethnomedicinal uses of leaves for species belonging to the genus Mitragyna with reference to the botany and known chemistry in order to highlight areas of interest for products currently being sold as kratom.
A literature search was conducted using Web of Science, Google Scholar, the Royal Museum for Central Africa, Internet Archive, Hathi Trust, and Biodiversity Heritage Library search engines in the spring of 2015, fall of 2016 and winter of 2017 to document uses of bark, leaf and root material.
Leaves of M. speciosa (kratom) had the most common documented ethnomedicinal uses as an opium substitute or remedy for addiction. Other species of Mitragyna were reportedly used for treating pain, however the mode of preparation was most often cited as topical application. Other uses of Mitragyna included treatment of fever, skin infections, and as a mild anxiolytic.
Mitragyna species have been used medicinally in various parts of the world and that there is significant traditional evidence of use. Modern products that include formulations as topical application of liniments, balms or tinctures may provide effective alternatives for treatment of certain types of pains. Future research is required to establish safety and toxicology limits, medicinal chemistry parameters and the potential for different physiological responses among varying genetic populations to support regulatory requirements for Mitragyna spp.
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Bile salts are potent antimicrobial agents and are an important component of innate defenses in the intestine, giving protection against invasive organisms. They play an important role in determining ...microbial ecology of the intestine and alterations in their levels can lead to increased colonization by pathogens. We have previously demonstrated survival of the opportunistic pathogen
in the human colonic model. Thus investigating the interaction between
and bile salts is an important factor in understanding its ability to colonize in the host intestine. Harnessing bile salts may also give a new avenue to explore in the development of therapeutic strategies to control drug resistant bacteria. Despite this importance, the antibacterial activity of bile salts on
is poorly understood. In this study, we investigated the antibacterial effects of the major unconjugated and conjugated bile salts on
. Several concentration-dependent antibacterial mechanisms were found. Unconjugated bile salts at their minimum inhibitory concentration (cholic and deoxycholic acid at 20 and 1 mM, respectively) killed
, and this was associated with increased membrane disruption and leakage of cellular contents. Unconjugated bile salts (cholic and deoxycholic acid at 8 and 0.4 mM, respectively) and conjugated bile salts (glycocholic and taurocholic acid at 20 mM) at their sub inhibitory concentrations were still able to inhibit growth through disruption of the proton motive force and increased membrane permeability. We also demonstrated that unconjugated bile salts possess more potent antibacterial action on
than conjugated bile salts.
Nanoindentation has become ubiquitous for the measurement of mechanical properties at ever-decreasing scales of interest, including some studies that have explored the atomic-level origins of ...plasticity in perfect crystals. With substantial guidance from atomistic simulations, the onset of plasticity during nanoindentation is now widely believed to be associated with homogeneous dislocation nucleation. However, to date there has been no compelling quantitative experimental support for the atomic-scale mechanisms predicted by atomistic simulations. Our purpose here is to significantly advance the quantitative potential of nanoindentation experiments for the study of dislocation nucleation. This is accomplished through the development and application of high-temperature nanoindentation testing, and the introduction of statistical methods to quantitatively evaluate data. The combined use of these techniques suggests an unexpected picture of incipient plasticity that involves heterogeneous nucleation sites, and which has not been anticipated by atomistic simulations.
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