Phytophthora verrucosa in Association With Toe Rot of Tomatoes

1. The symptoms of Toe Rot of Tomato roots have been detailed and a description of P. verrucosa given. 2. Reproductive structures, on which the identify of the fungus depends, were produced very irregularly . 3. Repeated attempts to derive a pure culture of the fungus from roots plated on a variety of media met with no success. Other Phycomy-cetous fungi of a vegetative nature were present in sufficient quantity to confuse the issue. 4. An attempt was made to isolate P. verrucosa from oospores which had been subjected to various pretreatments before germination. Initial vegetative hyphae were produced on a few occasions, but subsequent growth could not be sustained. 5. Information was obtained regarding the mode of germination of oospores of this species. Germination may take place in a "direct" method, producing branching hyphae, or "indirectly" with the formation of vesicles and the release of zoospores from these. 6. Toe Rot symptoms have been produced by plant- ing in diseased soil, but oogonia to confirm the presence of P. verrucosa were frequently lacking. P. verrucosa was induced artificially, however, by immersing the roots of seedlings for 6 days in water in which oogonia had borne vesicles and these had become evacuated. Oogonia were found on these seedlings 16 days after immersion. 7. As oogonia of P. verrucosa were not invariably present as evidence of infection by that fungus, a record was made of other fungal flora recurring on Toe Rot plants. None of these appear in themselves to be sufficiently actively parasitic to act as Pathogen. P. verrucosa is therefore still regarded as the primary cause. The Toe Rot symptoms may be produced by the fungus in a vegetative state, unidentifiable, in the absence of oogonia, as P. verrucosa. 8. Control experiments were set up. Owing to the sporadic nature of the infection in untreated sections, no true basis for comparison was available. A fuller understanding of the conditions favouring attack is necessary before satisfactory control measures can be planned

The efficiencies of generating cluster states with weak non-linearities

We propose a scalable approach to building cluster states of matter qubits using coherent states of light. Recent work on the subject relies on the use of single photonic qubits in the measurement process. These schemes can be made robust to detector loss, spontaneous emission and cavity mismatching but as a consequence the overhead costs grow rapidly, in particular when considering single photon loss. In contrast, our approach uses continuous variables and highly efficient homodyne measurements. We present a two-qubit scheme, with a simple bucket measurement system yielding an entangling operation with success probability 1/2. Then we extend this to a three-qubit interaction, increasing this probability to 3/4. We discuss the important issues of the overhead cost and the time scaling. This leads to a "no-measurement" approach to building cluster states, making use of geometric phases in phase space.Comment: 21 pages, to appear in special issue of New J. Phys. on "Measurement-Based Quantum Information Processing

Experiences of aspiring school principals receiving coaching as part of a leadership development programme

Purpose This paper adds depth to our understanding of how coaching works by exploring the experiences of 14 aspiring school principals who received one-to-one leadership coaching as part of a leadership development programme. Design/methodology/approach This study adopts a phenomenological approach. Individual semi-structured interviews were conducted with the participants. Thematic analysis was used to code the data and identify themes. Findings This paper reports on four themes based on the experiences of the participants: having time to reflect, feeling safe to explore, focussing on what's important for me and experiencing positive emotions. Research limitations/implications The findings are unique to the participants who volunteered to take part in this study and therefore not representative of a general population of aspiring educational leaders. Further research is needed into the possible benefits of coaching to support educators undergoing leadership training. Practical implications The findings raise a potential dilemma within the teaching profession about the use of educators' time; while they need to give time and attention to multiple stakeholders, they also need to protect time for their own development and self-reflection. Based on the reported experiences of the participants in this study, it is recommended that coaching be considered a component of professional development for educational leaders. Originality/value This paper adds to the growing research base for coaching in education, providing a unique insight into the experiences of aspiring school principals who received one-to-one leadership coaching as part of a leadership development programme

Giant optical Faraday rotation induced by a single electron spin in a quantum dot: Applications to entangling remote spins via a single photon

We propose a quantum non-demolition method - giant Faraday rotation - to detect a single electron spin in a quantum dot inside a microcavity where negatively-charged exciton strongly couples to the cavity mode. Left- and right-circularly polarized light reflected from the cavity feels different phase shifts due to cavity quantum electrodynamics and the optical spin selection rule. This yields giant and tunable Faraday rotation which can be easily detected experimentally. Based on this spin-detection technique, a scalable scheme to create an arbitrary amount of entanglement between two or more remote spins via a single photon is proposed.Comment: 5 pages, 3 figure

Occupational stress facing nurse academics—A mixed-methods systematic review

© 2019 John Wiley & Sons Ltd Aim: To better understand occupational stress faced by nurse academics. Methods: A mixed-methods systematic review, following the Joanna Briggs Institute [JBI], (Joanna Briggs Institute Reviewers’ Manual: 2014 edition, 2014) process. Studies were assessed for quality and risk of bias by using standardised critical appraisal instruments from the Joanna Briggs Institute. In addition, processes and reporting were checked against the Equator guidelines. See Appendix S1. Results: The review revealed that nursing academics do experience occupational stress, including burnout. Occupational stress for academic nurses is associated with various factors including work–life balance, workload issues, resources and support, and adapting to change. However, much of the literature focuses on nurses during the initial transition from clinical to academic environment, with rather less focus on established mid-to-late career nurse academics. Discussion: Occupational stress and burnout are evident in the university academic workforce, adversely affecting the well-being of academic nurses, and the long-term sustainability of the academic nursing workforce. While there is considerable literature focusing on the novice academic nurse, particularly during the transition period, rather less is known about occupational stress among academic nurses across the career trajectory. Various strategies to deal with the negative consequences of occupational stress are identified, including (a) quality mentors for novice and younger nursing academics; (b) training in resilience building for novice academics; (c) supporting collegial relationships and reducing bullying; (d) assistance for professional development and research; (e) better support and resources to overcome increasing workloads; and (f) greater work-related empowerment to enhance job satisfaction. Conclusion: There is a need for a broader whole-of-career research focus to more fully identify, explore and mitigate the occupational stressors that negatively affect the academic nurse workforce. Relevance to clinical practice: A strong and resilient academic nurse workforce is essential for the sustainability of the profession. Organisations should review their work practices and provide greater work-related empowerment to reduce occupational stressors among nursing academics

Schrodinger cats and their power for quantum information processing

We outline a toolbox comprised of passive optical elements, single photon detection and superpositions of coherent states (Schrodinger cat states). Such a toolbox is a powerful collection of primitives for quantum information processing tasks. We illustrate its use by outlining a proposal for universal quantum computation. We utilize this toolbox for quantum metrology applications, for instance weak force measurements and precise phase estimation. We show in both these cases that a sensitivity at the Heisenberg limit is achievable.Comment: 10 pages, 5 figures; Submitted to a Special Issue of J. Opt. B on "Fluctuations and Noise in Photonics and Quantum Optics" (Herman Haus Memorial Issue

Spectral Effects of Strong Chi-2 Non-Linearity for Quantum Processing

Optical $\chi^{(2)}$ non-linearity can be used for parametric amplification and producing down-converted entangled photon pairs that have broad applications. It is known that weak non-linear media exhibit dispersion and produce a frequency response. It is therefore of interest to know how spectral effects of a strong $\chi^{(2)}$ crystal affect the performance. Here we model the spectral effects of the dispersion of a strong $\chi^{(2)}$ crystal and illustrate how this affects its ability to perform Bell measurements and influence the performance of a quantum gates that employ such a Bell measurement. We show that a Dyson series expansion of the unitary operator is necessary in general, leading to unwanted spectral entanglement. We identify a limiting situation employing periodic poling, in which a Taylor series expansion is a good approximation and this entanglement can be removed.Comment: Will be submitted to PR

High speed quantum gates with cavity quantum electrodynamics

Cavity quantum electrodynamic schemes for quantum gates are amongst the earliest quantum computing proposals. Despite continued progress, and the dramatic recent demonstration of photon blockade, there are still issues with optimal coupling and gate operation involving high-quality cavities. Here we show dynamic control techniques that allow scalable cavity-QED based quantum gates, that use the full bandwidth of the cavities. When applied to quantum gates, these techniques allow an order of magnitude increase in operating speed, and two orders of magnitude reduction in cavity Q, over passive cavity-QED architectures. Our methods exploit Stark shift based Q-switching, and are ideally suited to solid-state integrated optical approaches to quantum computing.Comment: 4 pages, 3 figures, minor revision

Single photon quantum non-demolition in the presence of inhomogeneous broadening

Electromagnetically induced transparency (EIT) has been often proposed for generating nonlinear optical effects at the single photon level; in particular, as a means to effect a quantum non-demolition measurement of a single photon field. Previous treatments have usually considered homogeneously broadened samples, but realisations in any medium will have to contend with inhomogeneous broadening. Here we reappraise an earlier scheme [Munro \textit{et al.} Phys. Rev. A \textbf{71}, 033819 (2005)] with respect to inhomogeneities and show an alternative mode of operation that is preferred in an inhomogeneous environment. We further show the implications of these results on a potential implementation in diamond containing nitrogen-vacancy colour centres. Our modelling shows that single mode waveguide structures of length $200 \mu\mathrm{m}$ in single-crystal diamond containing a dilute ensemble of NV$^-$ of only 200 centres are sufficient for quantum non-demolition measurements using EIT-based weak nonlinear interactions.Comment: 21 pages, 9 figures (some in colour) at low resolution for arXiv purpose