Bumblebees of the Azores (Apidae: Bombus)

Bombus terrestris and Bombus pratorum were found for the first time in the Azores in 2005. Until then Bombus ruderatus was the only bumblebee species known from this group of nine midAtlantic islands. The identity of B. terrestris was confirmed by DNA barcoding

Genuine Counterfactual Communication with a Nanophotonic Processor

In standard communication information is carried by particles or waves. Counterintuitively, in counterfactual communication particles and information can travel in opposite directions. The quantum Zeno effect allows Bob to transmit a message to Alice by encoding information in particles he never interacts with. The first suggested protocol not only required thousands of ideal optical components, but also resulted in a so-called "weak trace" of the particles having travelled from Bob to Alice, calling the scalability and counterfactuality of previous proposals and experiments into question. Here we overcome these challenges, implementing a new protocol in a programmable nanophotonic processor, based on reconfigurable silicon-on-insulator waveguides that operate at telecom wavelengths. This, together with our telecom single-photon source and highly-efficient superconducting nanowire single-photon detectors, provides a versatile and stable platform for a high-fidelity implementation of genuinely trace-free counterfactual communication, allowing us to actively tune the number of steps in the Zeno measurement, and achieve a bit error probability below 1%, with neither post-selection nor a weak trace. Our demonstration shows how our programmable nanophotonic processor could be applied to more complex counterfactual tasks and quantum information protocols.Comment: 6 pages, 4 figure

Experimental Quantum Hamiltonian Learning

Efficiently characterising quantum systems, verifying operations of quantum devices and validating underpinning physical models, are central challenges for the development of quantum technologies and for our continued understanding of foundational physics. Machine-learning enhanced by quantum simulators has been proposed as a route to improve the computational cost of performing these studies. Here we interface two different quantum systems through a classical channel - a silicon-photonics quantum simulator and an electron spin in a diamond nitrogen-vacancy centre - and use the former to learn the latter's Hamiltonian via Bayesian inference. We learn the salient Hamiltonian parameter with an uncertainty of approximately $10^{-5}$. Furthermore, an observed saturation in the learning algorithm suggests deficiencies in the underlying Hamiltonian model, which we exploit to further improve the model itself. We go on to implement an interactive version of the protocol and experimentally show its ability to characterise the operation of the quantum photonic device. This work demonstrates powerful new quantum-enhanced techniques for investigating foundational physical models and characterising quantum technologies

The Different Structures of the Two Classes of Starless Cores

We describe a model for the thermal and dynamical equilibrium of starless cores that includes the radiative transfer of the gas and dust and simple CO chemistry. The model shows that the structure and behavior of the cores is significantly different depending on whether the central density is either above or below about 10^5 cm-3. This density is significant as the critical density for gas cooling by gas-dust collisions and also as the critical density for dynamical stability, given the typical properties of the starless cores. The starless cores thus divide into two classes that we refer to as thermally super-critical and thermally sub-critical.This two-class distinction allows an improved interpretation of the different observational data of starless cores within a single model.Comment: ApJ in pres

No imminent quantum supremacy by boson sampling

It is predicted that quantum computers will dramatically outperform their conventional counterparts. However, large-scale universal quantum computers are yet to be built. Boson sampling is a rudimentary quantum algorithm tailored to the platform of photons in linear optics, which has sparked interest as a rapid way to demonstrate this quantum supremacy. Photon statistics are governed by intractable matrix functions known as permanents, which suggests that sampling from the distribution obtained by injecting photons into a linear-optical network could be solved more quickly by a photonic experiment than by a classical computer. The contrast between the apparently awesome challenge faced by any classical sampling algorithm and the apparently near-term experimental resources required for a large boson sampling experiment has raised expectations that quantum supremacy by boson sampling is on the horizon. Here we present classical boson sampling algorithms and theoretical analyses of prospects for scaling boson sampling experiments, showing that near-term quantum supremacy via boson sampling is unlikely. While the largest boson sampling experiments reported so far are with 5 photons, our classical algorithm, based on Metropolised independence sampling (MIS), allowed the boson sampling problem to be solved for 30 photons with standard computing hardware. We argue that the impact of experimental photon losses means that demonstrating quantum supremacy by boson sampling would require a step change in technology.Comment: 25 pages, 9 figures. Comments welcom

Food geographies I: relational foodscapes and the busy-ness of being more-than-food

The study of foodscapes has spread throughout geography at the same time as food scholarship has spearheaded post-disciplinary research. This report argues that geographers have taken to post-disciplinarity to explore the ways that food is ‘more-than-food’ through analyses of the visceral nature of eating and politics and the vital (re)materializations of food’s cultural geographies. Visceral food geographies illuminate what I call the ‘contingent relationalities’ of food in the critical evaluation of the indeterminate, situated politics of ‘feeling food’ and those of the embodied collectivities of obesity. Questions remain, however, about how a visceral framework might be deployed for broader critiques within foodscapes and the study of human geography. The study of food’s vital materialisms opens up investigation into the practices of the ‘makings’ of meat, food waste and eating networks. Analysis of affect, embodiment and cultural practices is central to these theorizations and suggests consideration of the multiple materialisms of food, space and eating. There is, I contend, in the more radical, ‘post-relational’ approaches to food, the need for a note of caution. Exuberant claims for the ontological, vital agency of food should be tempered by, or at least run parallel to, critical questions of the real politik of political and practical agency in light of recent struggles over austerity, food poverty and food justice

Adenosine kinase inhibition selectively promotes rodent and porcine islet β-cell replication

Diabetes is a pathological condition characterized by relative insulin deficiency, persistent hyperglycemia, and, consequently, diffuse micro- and macrovascular disease. One therapeutic strategy is to amplify insulin-secretion capacity by increasing the number of the insulin-producing β cells without triggering a generalized proliferative response. Here, we present the development of a small-molecule screening platform for the identification of molecules that increase β-cell replication. Using this platform, we identify a class of compounds [adenosine kinase inhibitors (ADK-Is)] that promote replication of primary β cells in three species (mouse, rat, and pig). Furthermore, the replication effect of ADK-Is is cell type-selective: treatment of islet cell cultures with ADK-Is increases replication of β cells but not that of α cells, PP cells, or fibroblasts. Short-term in vivo treatment with an ADK-I also increases β-cell replication but not exocrine cell or hepatocyte replication. Therefore, we propose ADK inhibition as a strategy for the treatment of diabetes.Stem Cell and Regenerative Biolog

Three intermediate-mass YSOs with different properties emerging from the same natal cloud in IRAS 00117+6412

We observed with the VLA, PdBI, and SMA the centimeter and millimeter continuum, N2H+(1-0), and CO(2-1) emission associated with a dusty cloud harboring a nascent cluster with intermediate-mass protostars. At centimeter wavelengths we found a strong source, tracing a UCHII region, at the eastern edge of the dusty cloud, with a shell-like structure, and with the near-infrared counterpart falling in the center of the shell. This is presumably the most massive source of the forming cluster. About 15'' to the west of the UCHII region and well embedded in the dusty cloud, we detected a strong millimeter source, MM1, associated with centimeter and near-infrared emission. MM1 seems to be driving a prominent high-velocity CO bipolar outflow, and is embedded in a ridge of dense gas traced by N2H+. We estimated that MM1 is an intermediate-mass source in the Class 0/I phase. About 15'' to the south of MM1, and still more deeply embedded in the dusty cloud, we detected a compact millimeter source, MM2, with neither centimeter nor near-infrared emission, but with water maser emission. MM2 is associated with a clump of N2H+, whose kinematics reveal a clear velocity gradient and additionally we found signposts of infall motions. MM2, being deeply embedded within the dusty cloud, with an associated water maser but no hints of CO outflow emission, is an intriguing object, presumably of intermediate mass. In conclusion, the UCHII region is found at the border of a dusty cloud which is currently undergoing active star formation. Two intermediate-mass protostars in the dusty cloud seem to have formed after the UCHII region and have different properties related to the outflow phenomenon.Comment: accepted to Astronomy and Astrophysic

Patterns of homozygosity in insular and continental goat breeds

Background: Genetic isolation of breeds may result in a significant loss of diversity and have consequences on health and performance. In this study, we examined the effect of geographic isolation on caprine genetic diversity patterns by genotyping 480 individuals from 25 European and African breeds with the Goat SNP50 BeadChip and comparing patterns of homozygosity of insular and nearby continental breeds. Results: Among the breeds analysed, number and total length of ROH varied considerably and depending on breeds, ROH could cover a substantial fraction of the genome (up to 1.6 Gb in Icelandic goats). When compared with their continental counterparts, goats from Iceland, Madagascar, La Palma and Ireland (Bilberry and Arran) displayed a significant increase in ROH coverage, ROH number and F ROH values (P value < 0.05). Goats from Mediterranean islands represent a more complex case because certain populations displayed a significantly increased level of homozygosity (e.g. Girgentana) and others did not (e.g. Corse and Sarda). Correlations of number and total length of ROH for insular goat populations with the distance between islands and the nearest continental locations revealed an effect of extremely long distances on the patterns of homozygosity. Conclusions: These results indicate that the effects of insularization on the patterns of homozygosity are variable. Goats raised in Madagascar, Iceland, Ireland (Bilberry and Arran) and La Palma, show high levels of homozygosity, whereas those bred in Mediterranean islands display patterns of homozygosity that are similar to those found in continental populations. These results indicate that the diversity of insular goat populations is modulated by multiple factors such as geographic distribution, population size, demographic history, trading and breed management