469 research outputs found
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
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: âBelief and Commitmentâ; âInterpreting BFHIâ and âClimbing a
Mountainâ. 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
Australian parentsâ experiences with universal child and family health services
© 2018 Australian College of Nursing Ltd Background: Australian governments provide free services to promote maternal and child health, and to support parenting for families with children up to age five. Services are principally provided by dedicated child and family health nurses, but also by general practitioners, practice nurses, pharmacy nurses and midwives. Aim: This study aimed to examine the experiences of families with young children across Australia in accessing and receiving health care for well children, parenting support and advice from a range of providers. Methods: The study used quantitative and qualitative data from an online survey of 719 parents and carers with children aged up to five years. Findings: On quantitative scales, most respondents rated healthcare providers favourably for accessibility, credibility and their approach to families. However, qualitative responses revealed widely varying reactions to child and family health provision. Parents described both positive and negative experiences, highlighting elements of practice that are critical to consumer engagement. Discussion: Parents require health care and support that are accessible, consistent, affordable, encouraging, trustworthy, evidence-based and non-judgemental. Parents feel more confidence in the information and care provided by health professionals who are well-informed, resourceful and who respect their knowledge and beliefs. Conclusion: The findings demonstrate ways in which child and family health providers can engage and effectively support families with young children
Cold neutral atoms via charge exchange from excited state positronium: a proposal
We present a method for generating cold neutral atoms via charge exchange
reactions between trapped ions and Rydberg positronium. The high charge
exchange reaction cross section leads to efficient neutralisation of the ions
and since the positronium-ion mass ratio is small, the neutrals do not gain
appreciable kinetic energy in the process. When the original ions are cold the
reaction produces neutrals that can be trapped or further manipulated with
electromagnetic fields. Because a wide range of species can be targeted we
envisage that our scheme may enable experiments at low temperature that have
been hitherto intractable due to a lack of cooling methods. We present an
estimate for achievable temperatures, neutral number and density in an
experiment where the neutrals are formed at a milli-Kelvin temperature from
either directly or sympathetically cooled ions confined on an ion chip. The
neutrals may then be confined by their magnetic moment in a co-located magnetic
minimum well also formed on the chip. We discuss general experimental
requirements
Impact of heat stress on dairy cattle and selection strategies for thermotolerance: a review
Climate change is a problem that causes many environmental issues that impact the productivity of livestock species. One of the major issues associated with climate change is an increase of the frequency of hot days and heat waves, which increases the risk of heat stress for livestock species. Dairy cattle have been identified as being susceptible to heat stress due to their high metabolic heat load. Studies have shown heat stress impacts several biological processes that can result in large economic consequences. When heat stress occurs, dairy cattle employ several physiological and cellular mechanisms in order to dissipate heat and protect cells from damage. These mechanisms require an increase and diversion in energy toward protection and away from other biological processes. Therefore, in turn heat stress in dairy cattle can lead numerous issues including reductions in milk production and reproduction as well as increased risk for disease and mortality. This indicates a need to select dairy cattle that would be thermotolerant. Various selection strategies to confer thermotolerance have been discussed in the literature, including selecting for reduced milk production, crossbreeding with thermotolerant breeds, selecting based on physiological traits and most recently selecting for enhanced immune response. This review discusses the various issues associated with heat stress in dairy cattle and the pros and cons to the various selection strategies that have been proposed to select for thermotolerance in dairy cattle
Trapped ions in optical lattices for probing oscillator chain models
We show that a chain of trapped ions embedded in microtraps generated by an
optical lattice can be used to study oscillator models related to dry friction
and energy transport. Numerical calculations with realistic experimental
parameters demonstrate that both static and dynamic properties of the ion chain
change significantly as the optical lattice power is varied. Finally, we lay
out an experimental scheme to use the spin degree of freedom to probe the phase
space structure and quantum critical behavior of the ion chain
Towards quantum state tomography of a single polariton state of an atomic ensemble
We present a proposal and a feasibility study for the creation and quantum
state tomography of a single polariton state of an atomic ensemble. The
collective non-classical and non-Gaussian state of the ensemble is generated by
detection of a single forward scattered photon. The state is subsequently
characterized by atomic state tomography performed using strong dispersive
light-atoms interaction followed by a homodyne measurement on the transmitted
light. The proposal is backed by preliminary experimental results showing
projection noise limited sensitivity and a simulation demonstrating the
feasibility of the proposed method for detection of a non-classical and
non-Gaussian state of the mesoscopic atomic ensemble. This work represents the
first attempt of hybrid discrete-continuous variable quantum state processing
with atomic ensembles
Cooling in strongly correlated optical lattices: prospects and challenges
Optical lattices have emerged as ideal simulators for Hubbard models of
strongly correlated materials, such as the high-temperature superconducting
cuprates. In optical lattice experiments, microscopic parameters such as the
interaction strength between particles are well known and easily tunable.
Unfortunately, this benefit of using optical lattices to study Hubbard models
come with one clear disadvantage: the energy scales in atomic systems are
typically nanoKelvin compared with Kelvin in solids, with a correspondingly
miniscule temperature scale required to observe exotic phases such as d-wave
superconductivity. The ultra-low temperatures necessary to reach the regime in
which optical lattice simulation can have an impact-the domain in which our
theoretical understanding fails-have been a barrier to progress in this field.
To move forward, a concerted effort to develop new techniques for cooling and,
by extension, techniques to measure even lower temperatures. This article will
be devoted to discussing the concepts of cooling and thermometry, fundamental
sources of heat in optical lattice experiments, and a review of proposed and
implemented thermometry and cooling techniques.Comment: in review with Reports on Progress in Physic
A qualitative study of the experiences and expectations of women receiving in-patient postnatal care in one English maternity unit
Background Studies consistently highlight in-patient postnatal care as the area of maternity care women are least satisfied with. As part of a quality improvement study to promote a continuum of care from the birthing room to discharge home from hospital, we explored womenâs expectations and experiences of current inpatient care. Methods For this part of the study, qualitative data from semi-structured interviews were transcribed and analysed using content analyses to identify issues and concepts. Women were recruited from two postnatal wards in one large maternity unit in the South of England, with around 6,000 births a year. Results Twenty women, who had a vaginal or caesarean birth, were interviewed on the postnatal ward. Identified themes included; the impact of the ward environment; the impact of the attitude of staff; quality and level of support for breastfeeding; unmet information needs; and womenâs low expectations of hospital based postnatal care. Findings informed revision to the content and planning of in-patient postnatal care, results of which will be reported elsewhere. Conclusions Womenâs responses highlighted several areas where changes could be implemented. Staff should be aware that how they inter-act with women could make a difference to care as a positive or negative experience. The lack of support and inconsistent advice on breastfeeding highlights that units need to consider how individual staff communicate information to women. Units need to address how and when information on practical aspects of infant care is provided if women and their partners are to feel confident on the womanâs transfer home from hospital
Weidehaltung im alpinen Raum
Fachtagung fĂŒr Biologische Landwirtschaft - Weidehaltung im alpinen Raum
Inhalt der Tagung:
Ergebnisse zur Kurzrasenweidehaltung im Vergleich zur Schnittnutzung
Vergleich der Biomasseproduktion bei Schnittnutzung und Kurzrasenweide unter biologischen Bedingungen im ostalpinen Raum
Ampferregulierung durch intensive Beweidung möglich? Ergebnisse aus einem Exaktversuch sowie aus der Praxis
Ergebnisse zur Rindfleischproduktion auf der Weide - Kalbin, Ochse, Jungrind
Ergebnisse zum Einfluss der Abkalbesaison auf MilchkĂŒhe bei Vollweidehaltung
Erste Versuchsergebnisse und Erfahrungen zur Weidehaltung von Milchziegen
Parasitenbelastung von Weideziegen - Ergebnisse aus einem Versuch sowie aus Praxisuntersuchungen
Ergebnisse zur Almrekultivierung mit Schafen - Ănderungen in Pflanzenbestand und Vegetationsstruktu
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