Chip-based quantum key distribution Sibson, P; Erven, C; Godfrey, M ...
Nature communications,
02/2017, Letnik:
8, Številka:
1
Journal Article
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Improvement in secure transmission of information is an urgent need for governments, corporations and individuals. Quantum key distribution (QKD) promises security based on the laws of physics and ...has rapidly grown from proof-of-concept to robust demonstrations and deployment of commercial systems. Despite these advances, QKD has not been widely adopted, and large-scale deployment will likely require chip-based devices for improved performance, miniaturization and enhanced functionality. Here we report low error rate, GHz clocked QKD operation of an indium phosphide transmitter chip and a silicon oxynitride receiver chip-monolithically integrated devices using components and manufacturing processes from the telecommunications industry. We use the reconfigurability of these devices to demonstrate three prominent QKD protocols-BB84, Coherent One Way and Differential Phase Shift-with performance comparable to state-of-the-art. These devices, when combined with integrated single photon detectors, pave the way for successfully integrating QKD into future telecommunications networks.
The halo of the Milky Way provides a laboratory to study the properties of the shocked hot gas that is predicted by models of galaxy formation. There is observational evidence of energy injection ...into the halo from past activity in the nucleus of the Milky Way
; however, the origin of this energy (star formation or supermassive-black-hole activity) is uncertain, and the causal connection between nuclear structures and large-scale features has not been established unequivocally. Here we report soft-X-ray-emitting bubbles that extend approximately 14 kiloparsecs above and below the Galactic centre and include a structure in the southern sky analogous to the North Polar Spur. The sharp boundaries of these bubbles trace collisionless and non-radiative shocks, and corroborate the idea that the bubbles are not a remnant of a local supernova
but part of a vast Galaxy-scale structure closely related to features seen in γ-rays
. Large energy injections from the Galactic centre
are the most likely cause of both the γ-ray and X-ray bubbles. The latter have an estimated energy of around 10
erg, which is sufficient to perturb the structure, energy content and chemical enrichment of the circumgalactic medium of the Milky Way.
Dirac metals (gapless semiconductors) are believed to turn into Weyl metals when perturbations, which break either time reversal symmetry or inversion symmetry, are employed. However, no experimental ...evidence has been reported for the existence of Weyl fermions in three dimensions. Applying magnetic fields near the topological phase transition from a topological insulator to a band insulator in Bi1-xSbx we observe not only the weak antilocalization phenomenon in magnetoconductivity near zero magnetic fields (B<0.4 T), but also its upturn above 0.4 T only for E//B. This "incompatible" coexistence between weak antilocalization and "negative" magnetoresistivity is attributed to the Adler-Bell-Jackiw anomaly ("topological" E·B term) in the presence of weak antilocalization corrections.
The limit of application of the Scherrer equation Miranda, M. A. R.; Sasaki, J. M.
Acta crystallographica. Section A, Foundations and advances,
January 2018, 2018-Jan-01, 2018-01-01, 20180101, Letnik:
74, Številka:
1
Journal Article
Recenzirano
The Scherrer equation is a widely used tool to obtain crystallite size from polycrystalline samples. Its limit of applicability has been determined recently, using computer simulations, for a few ...structures and it was proposed that it is directly dependent on the linear absorption coefficient (μ0) and Bragg angle (gθB). In this work, a systematic study of the Scherrer limit is presented, where it is shown that it is equal to approximately 11.9% of the extinction length. It is also shown that absorption imposes a maximum value on it and that this maximum is directly proportional to sin gθB/μ0.
Study of the limit of applicability of the Scherrer equation has found it is approximately 11.9% of the extinction length and has a maximum value because of absorption.
A more complete understanding of how fear extinction alters neuronal activity and connectivity within fear circuits may aid in the development of strategies to treat human fear disorders. Using a ...c-fos-based transgenic mouse, we found that contextual fear extinction silenced basal amygdala (BA) excitatory neurons that had been previously activated during fear conditioning. We hypothesized that the silencing of BA fear neurons was caused by an action of extinction on BA inhibitory synapses. In support of this hypothesis, we found extinction-induced target-specific remodeling of BA perisomatic inhibitory synapses originating from parvalbumin and cholecystokinin-positive interneurons. Interestingly, the predicted changes in the balance of perisomatic inhibition matched the silent and active states of the target BA fear neurons. These observations suggest that target-specific changes in perisomatic inhibitory synapses represent a mechanism through which experience can sculpt the activation patterns within a neural circuit.
•Contextual fear extinction silences basal amygdala fear neurons•Perisomatic parvalbumin around silent fear neurons is increased after extinction•Perisomatic CB1 receptors around active fear neurons are increased after extinction•Behavior can cause target-specific remodeling of perisomatic inhibitory synapses
Fear extinction silences fear neurons in the basal amygdala. Trouche et al. show that contextual fear extinction causes changes in perisomatic inhibitory synapses around basal amygdala fear neurons and that these changes match the activation state of the fear neurons.
Defect influences on the photoactivity of ZnO nanoparticles prepared by a powdered coconut water (ACP) assisted synthesis have been studied. The crystalline phase and morphology of ZnO nanoparticles ...were effectively controlled by adjusting the calcination temperature (400–700 °C). An induced transition of hybrid Zn5(CO3)2(OH)6/ZnO nanoparticles to single-phase ZnO nanoparticles was obtained at 480 °C. The morphological analysis revealed a formation of ZnO nanoparticles with semispherical (∼6.5 nm)- and rod-like (∼96 nm) shapes when the calcination temperatures were 400 and 700 °C, respectively. Photoluminescence characterizations revealed several defects types in the samples with V Zn and V O + being in the self-assembly of semispherical- and rod-like ZnO nanoparticles. The photocatalytic activity of the ZnO nanoparticles was examined by assessing the degradation of methylene blue in an aqueous solution under low-intensity visible-light irradiation (∼3 W m–2). The results point toward the self-assembly of semispherical- and rod-like ZnO nanoparticles that had significantly better photocatalytic activity (∼31%) in comparison to that of spherical-agglomerated- or near-spherical-like species within 120 min of irradiation. The possible photocatalytic mechanism is discussed in detail, and the morphology-driven intrinsic V Zn+V O + defects are proposed to be among the active sites of the ZnO nanoparticles enhancing the photocatalytic activity.
Fluorescence in situ hybridization (FISH) reveals the abundance and positioning of nucleic acid sequences in fixed samples. Despite recent advances in multiplexed amplification of FISH signals, it ...remains challenging to achieve high levels of simultaneous amplification and sequential detection with high sampling efficiency and simple workflows. Here we introduce signal amplification by exchange reaction (SABER), which endows oligonucleotide-based FISH probes with long, single-stranded DNA concatemers that aggregate a multitude of short complementary fluorescent imager strands. We show that SABER amplified RNA and DNA FISH signals (5- to 450-fold) in fixed cells and tissues. We also applied 17 orthogonal amplifiers against chromosomal targets simultaneously and detected mRNAs with high efficiency. We then used 10-plex SABER-FISH to identify in vivo introduced enhancers with cell-type-specific activity in the mouse retina. SABER represents a simple and versatile molecular toolkit for rapid and cost-effective multiplexed imaging of nucleic acid targets.
Aims. We present a comprehensive X-ray study of the population of supernova remnants (SNRs) in the Large Magellanic Cloud (LMC). Using primarily XMM-Newton observations, we conduct a systematic ...spectral analysis of LMC SNRs to gain new insight into their evolution and the interplay with their host galaxy. Methods. We combined all the archival XMM-Newton observations of the LMC with those of our Very Large Programme LMC survey. We produced X-ray images and spectra of 51 SNRs, out of a list of 59 objects compiled from the literature and augmented with newly found objects. Using a careful modelling of the background, we consistently analysed all the X-ray spectra and measure temperatures, luminosities, and chemical compositions. The locations of SNRs are compared to the distributions of stars, cold gas, and warm gas in the LMC, and we investigated the connection between the SNRs and their local environment, characterised by various star formation histories. We tentatively typed all LMC SNRs, in order to constrain the ratio of core-collapse to type Ia SN rates in the LMC. We also compared the column densities derived from X-ray spectra to H i maps, thus probing the three-dimensional structure of the LMC. Results. This work provides the first homogeneous catalogue of the X-ray spectral properties of SNRs in the LMC. It offers a complete census of LMC remnants whose X-ray emission exhibits Fe K lines (13% of the sample), or reveals the contribution from hot supernova ejecta (39%), which both give clues to the progenitor types. The abundances of O, Ne, Mg, Si, and Fe in the hot phase of the LMC interstellar medium are found to be between 0.2 and 0.5 times the solar values with a lower abundance ratio α/Fe than in the Milky Way. The current ratio of core-collapse to type Ia SN rates in the LMC is constrained to NCC/NIa=1.35(-0.24+0.11), which is lower than in local SN surveys and galaxy clusters. Our comparison of the X-ray luminosity functions of SNRs in Local Group galaxies (LMC, SMC, M31, and M33) reveals an intriguing excess of bright objects in the LMC. Finally, we confirm that 30 Doradus and the LMC Bar are offset from the main disc of the LMC to the far and near sides, respectively.
Background and aims
The type IV intermediate filament, nestin, may be a candidate diagnostic marker for combined hepatocellular–cholangiocarcinoma (cHCC–CCA). Therefore, the significance of nestin as ...a diagnostic marker for cHCC–CCA categorized by the World Health Organization (WHO) 2019 classification and its relationship with clinicopathological features were examined in the present study.
Methods and results
Nestin expression was immunohistochemically assessed in the liver sections from 75 patients with cHCC–CCA, 22 with small duct‐type intrahepatic cholangiocarcinoma (iCCA), 20 with large duct‐type iCCA and 35 with hepatocellular carcinoma (HCC). Nestin expression and its relationship with clinicopathological features and genetic alterations were investigated in cHCC–CCA. Nestin expression was detected in significantly more patients with cHCC–CCA (66.7%) than in those with large duct‐type iCCA (5%) (P < 0.01), HCC (2.9%) (P < 0.01) and small duct‐type iCCA (40.9%) (P < 0.05). Nestin expression was partly associated with neural cell adhesion molecule (NCAM) and vimentin expression. Nestin expression was also observed in significantly more patients with small duct‐type iCCA than in those with large duct‐type iCCA and HCC (P < 0.01). Nestin‐positive cHCC–CCA was characterized by a smaller tumour size, the more frequent presence of cholangiolocellular carcinoma (CLC) components, a higher rate of p53 overexpression and a higher rate of multiple genetic alterations (P < 0.05). Furthermore, p53 overexpression was associated with a higher histological grade and multiple genetic alterations (P < 0.05) in nestin‐positive cHCC–CCA.
Conclusion
Nestin may be a useful diagnostic marker for a specific subgroup of cHCC–CCA and small duct‐type iCCA associated with CLC components, p53 mutations and multiple genetic alterations, which are related to stemness and multipotent differentiation.
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