Quantum simulation of the hexagonal Kitaev model with trapped ions

We present a detailed study of quantum simulations of coupled spin systems in surface-electrode ion-trap arrays, and illustrate our findings with a proposed implementation of the hexagonal Kitaev model [A. Kitaev, Annals of Physics 321,2 (2006)]. The effective (pseudo)spin interactions making up such quantum simulators are found to be proportional to the dipole-dipole interaction between the trapped ions, and are mediated by motion which can be driven by state-dependent forces. The precise forms of the trapping potentials and the interactions are derived in the presence of a surface electrode and a cover electrode. These results are the starting point to derive an optimized surface-electrode geometry for trapping ions in the desired honeycomb lattice of Kitaev's model, where we design the dipole-dipole interactions in a way that allows for coupling all three bond types of the model simultaneously, without the need for time discretization. Finally we propose a simple wire structure that can be incorporated in a microfabricated chip to generate localized state-dependent forces which drive the couplings prescribed by this particular model; such a wire structure should be adaptable to many other situations.Comment: 24 pages, 7 figures. v2: simplified the derivation of (28) without changing conclusions; minor edits. v3: minor edit

In vitro pancreatic carcinogenesis

Studies in our laboratories have indicated that pancreatic cancer originates not only from pancreatic ductal/ductular cells but also from within the Langerhans' islets, probably from reserve (precursor, stem) cells. To identify, enrich and characterize these cells, we established a long-term hamster islet culture and studied their growth, differentiation and response to the pancreatic carcinogen, N-nitrosobis(2-oxopropyl)amine (BOP). One group of cultured islets was treated in vitro with BOP (KL5B group) and the other group of islets served as an untreated control (KL5N group). During the early culture days, in both groups all cultured islets showed a progressive loss of endocrine cells and replacement by ductular, acinar and intermediary cells. However, all these cells disappeared after 35 days in culture and gave room to undifferentiated cells, which we believe represent stem cells. No differences were found between KL5N and KL5B cells with regard to cell growth and differentiation until day 35, when the growth of the KL5B cells accelerated and the cells underwent increasing pleomorphism and atypia. At day 133, KL5B cells but not KL5N cells showed colony formation in soft agar and formed invasive, poorly differentiated adenocarcinomas of the ductal type when transplanted into hamsters. All of these tumors showed mutation of the K-ras gene and extensive chromosomal damage. We concluded that like ductal/ductular cells, certain cell populations within islets are responsive to the carcinogenic effect of BOP. We could not ascertain whether these cells present a preexisting (stem, reserve) cell population within the islets or transdifferentiated islet cell

Electrostatics of Gapped and Finite Surface Electrodes

We present approximate methods for calculating the three-dimensional electric potentials of finite surface electrodes including gaps between electrodes, and estimate the effects of finite electrode thickness and an underlying dielectric substrate. As an example we optimize a radio-frequency surface-electrode ring ion trap, and find that each of these factors reduces the trapping secular frequencies by less than 5% in realistic situations. This small magnitude validates the usual assumption of neglecting the influences of gaps between electrodes and finite electrode extent.Comment: 9 pages, 9 figures (minor changes

Modified spin-wave theory with ordering vector optimization I: frustrated bosons on the spatially anisotropic triangular lattice

We investigate a system of frustrated hardcore bosons, modeled by an XY antiferromagnet on the spatially anisotropic triangular lattice, using Takahashi's modified spin-wave (MSW) theory. In particular we implement ordering vector optimization on the ordered reference state of MSW theory, which leads to significant improvement of the theory and accounts for quantum corrections to the classically ordered state. The MSW results at zero temperature compare favorably to exact diagonalization (ED) and projected entangled-pair state (PEPS) calculations. The resulting zero-temperature phase diagram includes a 1D quasi-ordered phase, a 2D Neel ordered phase, and a 2D spiraling ordered phase. We have strong indications that the various ordered or quasi-ordered phases are separated by spin-liquid phases with short-range correlations, in analogy to what has been predicted for the Heisenberg model on the same lattice. Within MSW theory we also explore the finite-temperature phase diagram. We find that the zero-temperature long-range-ordered phases turn into quasi-ordered phases (up to a Berezinskii-Kosterlitz-Thouless temperature), while zero-temperature quasi-ordered phases become short-range correlated at finite temperature. These results show that modified spin-wave theory is very well suited for describing ordered and quasi-ordered phases of frustrated XY spins (or, equivalently, of frustrated lattice bosons) both at zero and finite temperatures. While MSW theory, just as other theoretical methods, cannot describe spin-liquid phases, its breakdown provides a fast method for singling out Hamiltonians which may feature these intriguing quantum phases. We thus suggest a tool for guiding our search for interesting systems whose properties are necessarily studied with a physical quantum simulator.Comment: 40 pages, 16 figure

‘Being the bridge and the beacon’: a qualitative study of the characteristics and functions of the liaison role in child and family health services in Australia

© 2016 John Wiley & Sons Ltd Aims and objectives: This article explores the characteristics and functions of the liaison role in child and family health services in Australia. Background: Liaison roles are increasingly being used to improve communication between health services and professionals and to facilitate access to support for individuals and families in need. Nurses are commonly, although not always, the professionals who undertake these roles. Research on the role and outcomes of liaison positions in child and family health services is limited in Australia and internationally. Design: A qualitative interpretive design informed this study. Interviews and focus groups were conducted with 40 liaison and other health professionals, primarily nurses, working with families with newborn and young children in two Australian States. Data were analysed thematically. Results: Three major themes were identified reflecting the importance of defining the role and tasks which included building bridges between services and professionals, supporting families during transition between services and supporting clinicians. Several facilitators and barriers were identified, including concerns about sustainability of the roles. Conclusions: Professionals working in a liaison role in child and family health services emphasise that these positions have the potential to link services and professionals, thereby providing more effective care pathways for children and families especially for those with complex and multiple vulnerabilities. While a few children and family health services in Australia provide liaison services, the extent of liaison support and the outcomes for families in Australia is unknown. Relevance to clinical practice: Nurses working with children and families are the most likely health professionals to undertake a liaison role. In many nursing contexts, liaison roles are relatively new and those in the role have the responsibility to define the key purpose of their role. Liaison roles are multifaceted requiring the nurse to have excellent communication and negotiation skills to effectively link diverse professionals and services, while simultaneously engaging with and supporting vulnerable families and children. Nurses in these roles also support and educate clinical colleagues

Ten steps or climbing a mountain: A study of Australian health professionals' perceptions of implementing the baby friendly health initiative to protect, promote and support breastfeeding

Background: The Baby Friendly Hospital (Health) Initiative (BFHI) is a global initiative aimed at protecting, promoting and supporting breastfeeding and is based on the ten steps to successful breastfeeding. Worldwide, over 20,000 health facilities have attained BFHI accreditation but only 77 Australian hospitals (approximately 23%) have received accreditation. Few studies have investigated the factors that facilitate or hinder implementation of BFHI but it is acknowledged this is a major undertaking requiring strategic planning and change management throughout an institution. This paper examines the perceptions of BFHI held by midwives and nurses working in one Area Health Service in NSW, Australia. Methods: The study used an interpretive, qualitative approach. A total of 132 health professionals, working across four maternity units, two neonatal intensive care units and related community services, participated in 10 focus groups. Data were analysed using thematic analysis. Results: Three main themes were identified: ‘Belief and Commitment’; ‘Interpreting BFHI’ and ‘Climbing a Mountain’. Participants considered the BFHI implementation a high priority; an essential set of practices that would have positive benefits for babies and mothers both locally and globally as well as for health professionals. It was considered achievable but would take commitment and hard work to overcome the numerous challenges including a number of organisational constraints. There were, however, differing interpretations of what was required to attain BFHI accreditation with the potential that misinterpretation could hinder implementation. A model described by Greenhalgh and colleagues on adoption of innovation is drawn on to interpret the findings. Conclusion: Despite strong support for BFHI, the principles of this global strategy are interpreted differently by health professionals and further education and accurate information is required. It may be that the current processes used to disseminate and implement BFHI need to be reviewed. The findings suggest that there is a contradiction between the broad philosophical stance and best practice approach of this global strategy and the tendency for health professionals to focus on the ten steps as a set of tasks or a checklist to be accomplished. The perceived procedural approach to implementation may be contributing to lower rates of breastfeeding continuation

Phase Space Tomography of Matter-Wave Diffraction in the Talbot Regime

We report on the theoretical investigation of Wigner distribution function (WDF) reconstruction of the motional quantum state of large molecules in de Broglie interference. De Broglie interference of fullerenes and as the like already proves the wavelike behaviour of these heavy particles, while we aim to extract more quantitative information about the superposition quantum state in motion. We simulate the reconstruction of the WDF numerically based on an analytic probability distribution and investigate its properties by variation of parameters, which are relevant for the experiment. Even though the WDF described in the near-field experiment cannot be reconstructed completely, we observe negativity even in the partially reconstructed WDF. We further consider incoherent factors to simulate the experimental situation such as a finite number of slits, collimation, and particle-slit van der Waals interaction. From this we find experimental conditions to reconstruct the WDF from Talbot interference fringes in molecule Talbot-Lau interferometry.Comment: 16 pages, 9 figures, accepted at New Journal of Physic

Evaluation of two counterflow traps for testing behaviour-mediating compounds for the malaria vector Anopheles gambiae s.s. under semi-field conditions in Tanzania

BACKGROUND\ud \ud Evaluation of mosquito responses towards different trap-bait combinations in field trials is a time-consuming process that can be shortened by experiments in contained semi-field systems. Possible use of the BG Sentinel (BGS) trap to sample Anopheles gambiae s.s. was evaluated. The efficiency of this trap was compared with that of the Mosquito Magnet-X (MM-X) trap, when baited with foot odour alone or combinations of foot odour with carbon dioxide (CO2) or lemongrass as behaviour-modifying cues.\ud \ud METHODS\ud \ud Female An. gambiae s.s. were released in an experimental flight arena that was placed in a semi-field system and left overnight. Catch rates for the MM-X and BGS traps were recorded. Data were analysed by fitting a generalized linear model to the (n+1) transformed catches.\ud \ud RESULTS\ud \ud Both types of traps successfully captured mosquitoes with all odour cues used. When the BGS trap was tested against the MM-X trap in a choice assay with foot odour as bait, the BGS trap caught about three times as many mosquitoes as the MM-X trap (P = 0.002). Adding CO2 (500 ml/min) to foot odour increased the number of mosquitoes caught by 268% for the MM-X (P < 0.001) and 34% (P = 0.051) for the BGS trap, compared to foot odour alone. When lemongrass leaves were added to foot odour, mosquito catches were reduced by 39% (BGS, P < 0.001) and 38% (MM-X, P = 0.353), respectively.\ud \ud CONCLUSION\ud \ud The BGS trap shows high potential for field trials due to its simple construction and high catch rate when baited with human foot odour only. However, for rapid screening of different baits in a contained semi-field system, the superior discriminatory power of the MM-X trap is advantageous

Characteristics and service needs of women and babies admitted to residential parenting units in New South Wales: A mixed-methods study

© 2018 John Wiley & Sons Ltd Aims and objectives: To examine the characteristics and service needs of women and babies admitted to residential parenting services (RPS) in the first year following birth in New South Wales, Australia. Background: In Australia, there is a tiered system to support maternal, child and family health, which includes RPS. Design: Sequential explanatory mixed-methods design. Methods: Individual patient data were obtained from a random review of 10% of all medical records (n = 300 of 3,011 admissions) of women with an infant of <12 months of age who were admitted to RPS in 2013. Following review of the medical records, qualitative data were collected via interviews with eight women who accessed RPS. Chi-square analysis and Student's t test were used to analyse quantitative data. Qualitative data were analysed using a descriptive interpretive approach. An integrative approach was taken in reporting the findings. Results: Women admitted to the RPS were on average 32 years of age, were Australian born (72%) and had a university qualification (40%), and most were employed. The majority of women were primiparous (60%) and had a vaginal birth (61%). Women with male infants were much more likely to be admitted to the RPS (58%) compared to the NSW male-to-female ratio (51.3% vs. 48.7%). Over 50% of women reported mental health issues with 27% having an Edinburgh Postnatal Depression Scale score ≥13 on admission. The primary reason women sought parenting support was for sleep and settling (83%). During their stay, services used by women included social workers (44%), psychologists (52%) and psychiatrists (4.5%). Conclusion: Women who access RPS report psychosocial and mental health issues. Services provided by RPS support women during this challenging early parenting period by providing multidisciplinary, holistic and peer support. Relevance to clinical practice: A high prevalence of mental health issues identified in this study indicated a need for ongoing training and support for RPS staff. Ensuring clinicians have the appropriate skill sets to best support their clientele will maximise the outcomes for women and families who access RPS during the early parenting period