Erratum: Momentum-Resolved Observation of Thermal and Quantum Depletion in a Bose Gas [Phys. Rev. Lett. 117, 235303 (2016)].

This corrects the article DOI: 10.1103/PhysRevLett.117.235303.

Development of an inventory of biomedical imaging physics learning outcomes for MRI radiographers.

INTRODUCTION: MRI is highly physics based yet no research-based inventory of physics learning outcomes specific to MRI radiographers was found in the literature. The purpose of this study was the development of such an inventory using a multi-stakeholder, multi-disciplinary approach (as advised by the WHO) and which would support a previously published competence profile. METHODS: The inventory was developed in two phases: Phase 1: Development of an initial version of the learning outcomes inventory required to be able to deliver the competences via an analysis of textbooks and literature and validated by a small (n = 3) expert advisory group Phase 2: Final validation carried out via a bigger (n = 15) international group of subject matter experts (SMEs). Consensus was achieved via a dichotomous web-based questionnaire. RESULTS: At 70% level of consensus the expert group validated an inventory of biomedical physics learning outcomes consisting of 281 knowledge and skill statements. It is subdivided into two sections: 'fundamental' physics learning outcomes which are generic to all competences and 'additional' physics learning outcomes specific to each individual competence. CONCLUSION: The process used is sufficiently generic to be easily adapted to the development of physics learning outcome inventories in other specialties of radiography and for other healthcare professions whose work involves highly technological medical devices. As a result of this study, the current MRI curriculum would need to be revised as it was not based on a formal systematic research process and many learning outcomes are in fact missing.

Feeding dihydroquercetin to broiler chickens.

1. A total of 80 male Ross 308 broilers were used in a study to investigate the effect of dietary dihydroquercetin (DHQ) on growth performance variables, gastrointestinal tract (GIT) and immune organ development, glutathione peroxidase (GPx) and haemoglobin in blood, hepatic vitamin E content, dietary N-corrected metabolisable energy (AMEn) and nutrient retention coefficients when fed to broiler chickens from 7 to 35 d of age. 2. Two treatments were used in this study: control (C) and C + 0.5 g/kg extract of Siberian Larch (Larix sibirica) per kg feed, containing 85% DHQ. The diets were fed over 2 feeding phases, a grower phase from 7 to 28 d of age and a finisher phase from 28 to 35 d of age. The birds were reared under the breeder's recommended conditions. 3. In general, there were no effects of DHQ on growth performance of broiler chickens. However, the results of this experiment showed that there can be changes in the redness colour of the breast meat when DQH is fed. No negative effects of feeding DHQ at 0.5 g/kg diet were observed in this study. 4. Supplementation of poultry diets with DHQ under standard industry-rearing conditions did not improve the performance or any of the studied variables, except an increase of redness index of the breast fillets. Feeding DHQ at different doses and/or under more challenging conditions, e.g. heat stress, may, however, bring positive responses.

Is there a relationship between how MRI is learned and knowledge?

RATIONALE: The aim of this study was to discover whether a specialised undergraduate degree in magnetic resonance imaging (MRI) is a better way of educating MRI practitioners than experiential methods, and how necessary it is to first qualify as a radiographer to practice. This study compared the knowledge between individuals who qualify as a radiographer and then only learn MRI experientially (experiential practitioners), to those who learn only via a specialised undergraduate degree in MRI and enter practice directly without first qualifying as a radiographer (graduate practitioners). METHOD: Forty-eight participants (graduate practitioners n = 25, experiential practitioners n = 23) from four different clinical sites in the United States of America (USA) were recruited. An objective, structured, clinical examination (OSCE) was used to compare knowledge on the key topics. RESULTS: Graduate practitioners consistently achieved a higher percentage of correct answers than the experiential group in all five sections of the OSCE. The total score in the graduate group was statistically significantly higher than for the experiential group (p = 0.018). Means scores were graduate 63.18%, (SD 11.03), experiential 53.58% (SD 16.24) There was a correspondingly large Cohen's effect size (0.697) which indicated that the specialised undergraduate degree in MRI does have an impact on knowledge. CONCLUSION: A specialised undergraduate degree may be a beneficial way of learning MRI and it may not be necessary to first qualify as a radiographer to practice competently.

Opening the debate on MRI practitioner education - Is there a need for change?

RATIONALE: Magnetic Resonance Imaging (MRI) practitioners are traditionally radiographers who learn MRI experientially. This review opens the debate on whether this is the best way of learning MRI. It was conducted as part of a study exploring the value of direct-entry into MRI via a specialized undergraduate degree without first qualifying as a radiographer. METHOD: A narrative literature review using the search terms MRI, radiography education and specialist education (healthcare, radiography). FINDINGS: There is a lack of cohesive policy on how to educate imaging specialists. There is evidence that MRI practitioners lack knowledge and that current educational methods are failing. Direct entry via a specialized undergraduate degree is permitted in some countries, and research suggests that this is a beneficial way of learning MRI.

An international survey of MRI qualification and certification frameworks with an emphasis on identifying elements of good practice.

The purpose of the study was to survey MRI qualification and certification frameworks in the major English-speaking countries (Australia, New Zealand, US, Canada, UK, Ireland) with the aim of identifying elements of good practice. The intention is to incorporate these elements in a national framework that could be used in supporting an MRI specialist register. The study was conducted using document analysis of MRI qualification and certification documents from these states with data triangulated through a web-based questionnaire amongst an expert group of MRI radiographers (n = 59) from the same states. Based on the results of the study, recommendations have been put forward for those countries that are in the process of developing such frameworks. The main recommendations include that a professional or regulatory body externally accredits MRI programmes and that learning outcomes be based on an MRI competence profile that addresses current and forecasted needs of the particular country. The MRI competence profile should encompass a novice-to expert continuum and be referenced directly to a national qualification framework. Ideally each level of expertise should be assessed and evidenced by a portfolio of CPD activities, including clinical and management case studies appropriate to that level.

Momentum-Resolved Observation of Thermal and Quantum Depletion in a Bose Gas.

We report on the single-atom-resolved measurement of the distribution of momenta ℏk in a weakly interacting Bose gas after a 330 ms time of flight. We investigate it for various temperatures and clearly separate two contributions to the depletion of the condensate by their k dependence. The first one is the thermal depletion. The second contribution falls off as k^{-4}, and its magnitude increases with the in-trap condensate density as predicted by the Bogoliubov theory at zero temperature. These observations suggest associating it with the quantum depletion. How this contribution can survive the expansion of the released interacting condensate is an intriguing open question.

Characterization of a detector chain using a FPGA-based time-to-digital converter to reconstruct the three-dimensional coordinates of single particles at high flux.

We report on the development of a novel FPGA-based time-to-digital converter and its implementation in a detection chain that records the coordinates of single particles along three dimensions. The detector is composed of micro-channel plates mounted on top of a cross delay line and connected to fast electronics. We demonstrate continuous recording of the timing signals from the cross delay line at rates up to 4.1 × 10(6) s(-1) and three-dimensional reconstruction of the coordinates up to 3.2 × 10(6) particles per second. From the imaging of a calibrated structure we measure the in-plane resolution of the detector to be 140(20) µm at a flux of 3 × 10(5) particles per second. In addition, we analyze a method to estimate the resolution without placing any structure under vacuum, a significant practical improvement. While we use UV photons here, the results of this work apply to the detection of other kinds of particles.

Quantum Signature of Analog Hawking Radiation in Momentum Space.

We consider a sonic analog of a black hole realized in the one-dimensional flow of a Bose-Einstein condensate. Our theoretical analysis demonstrates that one- and two-body momentum distributions accessible by present-day experimental techniques provide clear direct evidence (i) of the occurrence of a sonic horizon, (ii) of the associated acoustic Hawking radiation, and (iii) of the quantum nature of the Hawking process. The signature of the quantum behavior persists even at temperatures larger than the chemical potential.

Atomic Hong-Ou-Mandel experiment.

Two-particle interference is a fundamental feature of quantum mechanics, and is even less intuitive than wave-particle duality for a single particle. In this duality, classical concepts--wave or particle--are still referred to, and interference happens in ordinary space-time. On the other hand, two-particle interference takes place in a mathematical space that has no classical counterpart. Entanglement lies at the heart of this interference, as it does in the fundamental tests of quantum mechanics involving the violation of Bell's inequalities. The Hong, Ou and Mandel experiment is a conceptually simpler situation, in which the interference between two-photon amplitudes also leads to behaviour impossible to describe using a simple classical model. Here we report the realization of the Hong, Ou and Mandel experiment using atoms instead of photons. We create a source that emits pairs of atoms, and cause one atom of each pair to enter one of the two input channels of a beam-splitter, and the other atom to enter the other input channel. When the atoms are spatially overlapped so that the two inputs are indistinguishable, the atoms always emerge together in one of the output channels. This result opens the way to testing Bell's inequalities involving mechanical observables of massive particles, such as momentum, using methods inspired by quantum optics, and to testing theories of the quantum-to-classical transition. Our work also demonstrates a new way to benchmark non-classical atom sources that may be of interest for quantum information processing and quantum simulation.

Influence of gold coating and interplate voltage on the performance of chevron micro-channel plates for temporally and spatially resolved single particle detection.

We present a study of two different sets of Micro-Channel Plates used for time and space resolved single particle detection. We investigate the effects of the gold coating and that of introducing an interplate voltage between the spatially separated plates. We find that the gold coating increases the count rate of the detector and the pulse amplitude as previously reported for non-spatially resolved setups. The interplate voltage also increases count rates. In addition, we find that a non-zero interplate voltage improves the spatial accuracy in determining the arrival position of incoming single particles (by ~20%) while the gold coating has a negative effect (by ~30%).

Violation of the Cauchy-Schwarz inequality with matter waves.

The Cauchy-Schwarz (CS) inequality-one of the most widely used and important inequalities in mathematics-can be formulated as an upper bound to the strength of correlations between classically fluctuating quantities. Quantum-mechanical correlations can, however, exceed classical bounds. Here we realize four-wave mixing of atomic matter waves using colliding Bose-Einstein condensates, and demonstrate the violation of a multimode CS inequality for atom number correlations in opposite zones of the collision halo. The correlated atoms have large spatial separations and therefore open new opportunities for extending fundamental quantum-nonlocality tests to ensembles of massive particles.

An oscillator circuit to produce a radio-frequency discharge and application to metastable helium saturated absorption spectroscopy.

We present a rf gas discharge apparatus which provides an atomic frequency reference for laser manipulation of metastable helium. We discuss the biasing and operation of a Colpitts oscillator in which the discharge coil is part of the oscillator circuit. Radiofrequency radiation is reduced by placing the entire oscillator in a metal enclosure.

Acoustic analog to the dynamical Casimir effect in a Bose-Einstein condensate.

We have modulated the density of a trapped Bose-Einstein condensate by changing the trap stiffness, thereby modulating the speed of sound. We observe the creation of correlated excitations with equal and opposite momenta, and show that for a well-defined modulation frequency, the frequency of the excitations is half that of the trap modulation frequency.

ELR510444, a novel microtubule disruptor with multiple mechanisms of action.

Although several microtubule-targeting drugs are in clinical use, there remains a need to identify novel agents that can overcome the limitations of current therapies, including acquired and innate drug resistance and undesired side effects. In this study, we show that ELR510444 has potent microtubule-disrupting activity, causing a loss of cellular microtubules and the formation of aberrant mitotic spindles and leading to mitotic arrest and apoptosis of cancer cells. ELR510444 potently inhibited cell proliferation with an IC(50) value of 30.9 nM in MDA-MB-231 cells, inhibited the rate and extent of purified tubulin assembly, and displaced colchicine from tubulin, indicating that the drug directly interacts with tubulin at the colchicine-binding site. ELR510444 is not a substrate for the P-glycoprotein drug transporter and retains activity in ßIII-tubulin-overexpressing cell lines, suggesting that it circumvents both clinically relevant mechanisms of drug resistance to this class of agents. Our data show a close correlation between the concentration of ELR510444 required for inhibition of cellular proliferation and that required to cause significant loss of cellular microtubule density, consistent with its activity as a microtubule depolymerizer. ELR510444 also shows potent antitumor activity in the MDA-MB-231 xenograft model with at least a 2-fold therapeutic window. Studies in tumor endothelial cells show that a low concentration of ELR510444 (30 nM) rapidly alters endothelial cell shape, similar to the effect of the vascular disrupting agent combretastatin A4. These results suggest that ELR510444 is a novel microtubule-disrupting agent with potential antivascular effects and in vivo antitumor efficacy.

Spontaneous four-wave mixing of de Broglie waves: beyond optics.

We investigate the atom-optical analog of degenerate four-wave mixing by colliding two Bose-Einstein condensates of metastable helium. The momentum distribution of the scattered atoms is measured in three dimensions. A simple analogy with photon phase matching conditions suggests a spherical final distribution. We find, however, that it is an ellipsoid with radii smaller than the initial collision momenta. Numerical and analytical calculations agree with this and reveal the interplay between many-body effects, mean-field interaction, and the anisotropy of the source condensate.

Sub-poissonian number differences in four-wave mixing of matter waves.

We demonstrate sub-Poissonian number differences in four-wave mixing of Bose-Einstein condensates of metastable helium. The collision between two Bose-Einstein condensates produces a scattering halo populated by pairs of atoms of opposing velocities, which we divide into several symmetric zones. We show that the atom number difference for opposing zones has sub-Poissonian noise fluctuations, whereas that of nonopposing zones is well described by shot noise. The atom pairs produced in a dual number state are well adapted to sub-shot-noise interferometry and studies of Einstein-Podolsky-Rosen-type nonlocality tests.

Observation of atom pairs in spontaneous four-wave mixing of two colliding Bose-Einstein condensates.

We study atom scattering from two colliding Bose-Einstein condensates using a position sensitive, time resolved, single atom detector. In analogy to quantum optics, the process can also be thought of as spontaneous, degenerate four-wave mixing of de Broglie waves. We find a clear correlation between atoms with opposite momenta, demonstrating pair production in the scattering process. We also observe a Hanbury Brown-Twiss correlation for collinear momenta, which permits an independent measurement of the size of the pair production source and thus the size of the spatial mode. The back-to-back pairs occupy very nearly two oppositely directed spatial modes, a promising feature for future quantum optics experiments.

Roughness suppression via rapid current modulation on an Atom chip.

We present a method to suppress the roughness of the potential of a wire-based, magnetic atom guide: modulating the wire current at a few tens of kHz, the potential roughness, which is proportional to the wire current, averages to zero. Using ultracold 87Rb clouds, we show experimentally that modulation reduces the roughness by at least a factor five without measurable heating or atom loss. This roughness suppression results in a dramatic reduction of the damping of center-of-mass oscillations.

Comparison of the Hanbury Brown-Twiss effect for bosons and fermions.

Fifty years ago, Hanbury Brown and Twiss (HBT) discovered photon bunching in light emitted by a chaotic source, highlighting the importance of two-photon correlations and stimulating the development of modern quantum optics. The quantum interpretation of bunching relies on the constructive interference between amplitudes involving two indistinguishable photons, and its additive character is intimately linked to the Bose nature of photons. Advances in atom cooling and detection have led to the observation and full characterization of the atomic analogue of the HBT effect with bosonic atoms. By contrast, fermions should reveal an antibunching effect (a tendency to avoid each other). Antibunching of fermions is associated with destructive two-particle interference, and is related to the Pauli principle forbidding more than one identical fermion to occupy the same quantum state. Here we report an experimental comparison of the fermionic and bosonic HBT effects in the same apparatus, using two different isotopes of helium: (3)He (a fermion) and 4He (a boson). Ordinary attractive or repulsive interactions between atoms are negligible; therefore, the contrasting bunching and antibunching behaviour that we observe can be fully attributed to the different quantum statistics of each atomic species. Our results show how atom-atom correlation measurements can be used to reveal details in the spatial density or momentum correlations in an atomic ensemble. They also enable the direct observation of phase effects linked to the quantum statistics of a many-body system, which may facilitate the study of more exotic situations.