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

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

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

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

The Quaternary sequence of the Nahr el Kebir, NW Syria: An important repository for evidence of Palaeolithic occupation and landscape evolution in the eastern Mediterranean

The third largest river in Syria, the Nahr el Kebir has a well-preserved record of river-terrace deposits that have produced substantial Palaeolithic artefact assemblages both from within the terrace deposits and from the land surfaces above and around them. At the Mediterranean coastline, the fluvial gravels interdigitate with raised shoreline terrace deposits, providing an insight into the temporal and climatic relations of both of these important geomorphological and morphostratigraphical archives, as well as their relationship with each other. New research is reported here on the Pleistocene geology and geomorphology of the Nahr el Kebir and the associated Palaeolithic archaeology, the latter having been reinterpreted based on reassessment of museum collections arising from earlier detailed work. Field visits revealed an additional, hitherto unrecognized low-level river terrace, whereas one of the previously recognized Palaeolithic levels can be shown to coincide with slope deposits that armour hilltops rather than representing a genuine fluvial formation. The new understanding of these geomorphological and sedimentary archives supports ideas that this corner of the Mediterranean has experienced unusually rapid uplift during the recent Quaternary, as a result of which the local rivers, including the Kebir, have deepened their valleys rapidly. Consequently, only the recent part of the Quaternary is recorded in the Kebir system and the ages envisaged previously for the terrace deposits and the Palaeolithic artefact assemblages were considerable overestimates in many cases, a finding that has significance for their correlation with those from the wider region. Reassessment of the Palaeolithic archaeology suggests a settlement history initially dominated by groups using handaxes, alongside simple core working (0.5–0.3 Ma), followed by a major change with the appearance of Levallois core working alongside handaxes, marking the transition to the early Middle Palaeolithic

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