The First World War Centenary in the UK: ‘A Truly National Commemoration’?

Prime Minister David Cameron has called for ‘a truly national commemoration of the First World War’. This article shows this to be problematic, politicised and contested. This is in part due to the elision of English and British histories. Scottish, Welsh and Irish responses are noted, and the role and commemorations of ‘our friends in the Commonwealth’. There are tensions around interpretations of empire and race. There has been a failure to appreciate that the debates about the legacies of the First World War are deeply entangled with those of colonialism

Optically addressing single rare-earth ions in a nanophotonic cavity

We demonstrate optical probing of spectrally resolved single Nd rare-earth ions in yttrium orthovanadate. The ions are coupled to a photonic crystal resonator and show strong enhancement of the optical emission rate via the Purcell effect, resulting in near radiatively limited single photon emission. The measured high coupling cooperativity between a single photon and the ion allows for the observation of coherent optical Rabi oscillations. This could enable optically controlled spin qubits, quantum logic gates, and spin-photon interfaces for future quantum networks

Estimate of the Spontaneous Mutation Rate in Chlamydomonas reinhardtii

The nature of spontaneous mutations, including their rate, distribution across the genome, and fitness consequences, is of central importance to biology. However, the low rate of mutation has made it difficult to study spontaneous mutagenesis, and few studies have directly addressed these questions. Here, we present a direct estimate of the mutation rate and a description of the properties of new spontaneous mutations in the unicellular green alga Chlamydomonas reinhardtii. We conducted a mutation accumulation experiment for ∼350 generations followed by whole-genome resequencing of two replicate lines. Our analysis identified a total of 14 mutations, including 5 short indels and 9 single base mutations, and no evidence of larger structural mutations. From this, we estimate a total mutation rate of 3.23 × 10(−10)/site/generation (95% C.I. 1.82 × 10(−10) to 5.23 × 10(−10)) and a single base mutation rate of 2.08 × 10(−10)/site/generation (95% C.I., 1.09 × 10(−10) to 3.74 × 10(−10)). We observed no mutations from A/T → G/C, suggesting a strong mutational bias toward A/T, although paradoxically, the GC content of the C. reinhardtii genome is very high. Our estimate is only the second direct estimate of the mutation rate from plants and among the lowest spontaneous base-substitution rates known in eukaryotes

Time-walk and jitter correction in SNSPDs at high count rates

Superconducting nanowire single-photon detectors (SNSPDs) are a leading detector type for time correlated single photon counting, especially in the near-infrared. When operated at high count rates, SNSPDs exhibit increased timing jitter caused by internal device properties and features of the RF amplification chain. Variations in RF pulse height and shape lead to variations in the latency of timing measurements. To compensate for this, we demonstrate a calibration method that correlates delays in detection events with the time elapsed between pulses. The increase in jitter at high rates can be largely canceled in software by applying corrections derived from the calibration process. We demonstrate our method with a single-pixel tungsten silicide SNSPD and show it decreases high count rate jitter. The technique is especially effective at removing a long tail that appears in the instrument response function at high count rates. At a count rate of 11.4 MCounts/s we reduce the full width at one percent maximum level (FW1%M) by 45%. The method therefore enables certain quantum communication protocols that are rate-limited by the (FW1%M) metric to operate almost twice as fast. \c{opyright} 2022. All rights reserved.Comment: 5 pages, 3 figure

Streaming Motions Towards the Supermassive Black Hole in NGC 1097

We have used GMOS-IFU and high resolution HST-ACS observations to map, in unprecedented detail, the gas velocity field and structure within the 0.7 kpc circumnuclear ring of the SBb LINER/Seyfert 1 galaxy NGC 1097. We find clear evidence of radial streaming motions associated with spiral structures leading to the unresolved (<3.5 parsecs) nucleus, which we interpret as part of the fueling chain by which gas is transported to the nuclear starburst and supermassive black hole.Comment: 4 pages, 3 figures using emulateapj. Accepted for publication in Astrophysical Journal Letters. Download high-resolution version from http://www.astro.uu.se/~kambiz/DOC/paper-N1097.pd

Waveguide-Coupled Superconducting Nanowire Single-Photon Detectors

We have demonstrated WSi-based superconducting nanowire single-photon detectors coupled to SiN_x waveguides with integrated ring resonators. This photonics platform enables the implementation of robust and efficient photon-counting detectors with fine spectral resolution near 1550 nm

The Distribution of High and Low Redshift Type Ia Supernovae

The distribution of high redshift Type Ia supernovae (SNe Ia) with respect to projected distance from the center of the host galaxy is studied and compared to the distribution of local SNe. The distribution of high-z SNe Ia is found to be similar to the local sample of SNe Ia discovered with CCDs, but different than the sample discovered photographically. This is shown to be due to the Shaw effect. These results have implications for the use of SNe Ia to determine cosmological parameters if the local sample of supernovae used to calibrate the light curve decline relationships is drawn from a sample discovered photographically. A K-S test shows that the probability that the high redshift SNe of the Supernova Cosmology Project are drawn from the same distribution as the low redshift calibrators of Riess et al. is 0.1%. This is a potential problem because photographically discovered SNe are preferentially discovered farther away from the galaxy nucleus, where SNe show a lower scatter in absolute magnitude, and are on average 0.3 magnitudes fainter than SNe located closer to the center of their host galaxy. This raises questions about whether or not the calibration SNe sample the full range of parameters potentially present in high redshift SNe Ia. The limited data available suggest that the calibration process is adequate; however, it would be preferable if high redshift SNe and the low redshift SNe used to calibrate them were drawn from the same sample, as subtle differences may be important. Data are also presented which suggest that the seeming anti-Malmquist trend noticed by Tammann et al.(1996, 1998) for SNe Ia in galaxies with Cepheid distances may be due to the location of the SNe in their host galaxies.Comment: 16 pages, 2 figures Accepted for publication in the Astrophysical Journa