370 research outputs found
Changes in nurses’ work associated with computerised information systems: Opportunities for international comparative studies using the revised Work Observation Method by Activity Timing (WOMBAT)
An important step in advancing global health through informatics is to understand how systems support health professionals to deliver improved services to patients. Studies in several countries have highlighted the potential for clinical information systems to change patterns of work and communication, and in particular have raised concerns that they reduce nurses’ time in direct care. However measuring the effects of systems on work is challenging and comparisons across studies have been hindered by a lack of standardised definitions and measurement tools. This paper describes the Work Observation Method by Activity Time (WOMBAT) technique version 1.0 and the ways in which the data generated can describe different aspects of health professionals’ work. In 2011 a revised WOMBAT version 2.0 was developed specifically to facilitate its use by research teams in different countries. The new features provide opportunities for international comparative studies of nurses’ work to be conducted
Channeling Effects in Direct Dark Matter Detectors
The channeling of the ion recoiling after a collision with a WIMP changes the
ionization signal in direct detection experiments, producing a larger signal
than otherwise expected. We give estimates of the fraction of channeled
recoiling ions in NaI (Tl), Si and Ge crystals using analytic models produced
since the 1960's and 70's to describe channeling and blocking effects. We find
that the channeling fraction of recoiling lattice nuclei is smaller than that
of ions that are injected into the crystal and that it is strongly temperature
dependent.Comment: 8 pages, 12 figures, To appear in the Proceedings of the sixth
International Workshop on the Dark Side of the Universe (DSU2010) Leon,
Guanajuato, Mexico 1-6 June 201
Recoiling Ion-Channeling in Direct Dark Matter Detectors
The channeling of the recoiling nucleus in crystalline detectors after a WIMP
collision would produce a larger scintillation or ionization signal in direct
detection experiments than otherwise expected. I present estimates of
channeling fractions obtained using analytic models developed from the 1960's
onwards to describe channeling and blocking effects. We find the fractions to
be too small to affect the fits to potential WIMP candidates. I also examine
the possibility of detecting a daily modulation of the dark matter signal due
to channeling.Comment: Talk presented at the DSU 2011 Conference, KITPC, Beijing, China,
Sept 26-30, 2011. 8 pages, 14 figures, jpconf.cls and jpconf11.clo necessary
to typese
Fisher zeros of the Q-state Potts model in the complex temperature plane for nonzero external magnetic field
The microcanonical transfer matrix is used to study the distribution of the
Fisher zeros of the Potts models in the complex temperature plane with
nonzero external magnetic field . Unlike the Ising model for
which has only a non-physical critical point (the Fisher edge singularity), the
Potts models have physical critical points for as well as the
Fisher edge singularities for . For the cross-over of the Fisher
zeros of the -state Potts model into those of the ()-state Potts model
is discussed, and the critical line of the three-state Potts ferromagnet is
determined. For we investigate the edge singularity for finite lattices
and compare our results with high-field, low-temperature series expansion of
Enting. For we find that the specific heat, magnetization,
susceptibility, and the density of zeros diverge at the Fisher edge singularity
with exponents , , and which satisfy the scaling
law .Comment: 24 pages, 7 figures, RevTeX, submitted to Physical Review
Density of states, Potts zeros, and Fisher zeros of the Q-state Potts model for continuous Q
The Q-state Potts model can be extended to noninteger and even complex Q in
the FK representation. In the FK representation the partition function,Z(Q,a),
is a polynomial in Q and v=a-1(a=e^-T) and the coefficients of this
polynomial,Phi(b,c), are the number of graphs on the lattice consisting of b
bonds and c connected clusters. We introduce the random-cluster transfer matrix
to compute Phi exactly on finite square lattices. Given the FK representation
of the partition function we begin by studying the critical Potts model
Z_{CP}=Z(Q,a_c), where a_c=1+sqrt{Q}. We find a set of zeros in the complex
w=sqrt{Q} plane that map to the Beraha numbers for real positive Q. We also
identify tilde{Q}_c(L), the value of Q for a lattice of width L above which the
locus of zeros in the complex p=v/sqrt{Q} plane lies on the unit circle. We
find that 1/tilde{Q}_c->0 as 1/L->0. We then study zeros of the AF Potts model
in the complex Q plane and determine Q_c(a), the largest value of Q for a fixed
value of a below which there is AF order. We find excellent agreement with
Q_c=(1-a)(a+3). We also investigate the locus of zeros of the FM Potts model in
the complex Q plane and confirm that Q_c=(a-1)^2. We show that the edge
singularity in the complex Q plane approaches Q_c as Q_c(L)~Q_c+AL^-y_q, and
determine the scaling exponent y_q. Finally, by finite size scaling of the
Fisher zeros near the AF critical point we determine the thermal exponent y_t
as a function of Q in the range 2<Q<3. We find that y_t is a smooth function of
Q and is well fit by y_t=(1+Au+Bu^2)/(C+Du) where u=u(Q). For Q=3 we find
y_t~0.6; however if we include lattices up to L=12 we find y_t~0.50.Comment: to appear in Physical Review
Yang-Lee Zeros of the Q-state Potts Model on Recursive Lattices
The Yang-Lee zeros of the Q-state Potts model on recursive lattices are
studied for non-integer values of Q. Considering 1D lattice as a Bethe lattice
with coordination number equal to two, the location of Yang-Lee zeros of 1D
ferromagnetic and antiferromagnetic Potts models is completely analyzed in
terms of neutral periodical points. Three different regimes for Yang-Lee zeros
are found for Q>1 and 0<Q<1. An exact analytical formula for the equation of
phase transition points is derived for the 1D case. It is shown that Yang-Lee
zeros of the Q-state Potts model on a Bethe lattice are located on arcs of
circles with the radius depending on Q and temperature for Q>1. Complex
magnetic field metastability regions are studied for the Q>1 and 0<Q<1 cases.
The Yang-Lee edge singularity exponents are calculated for both 1D and Bethe
lattice Potts models. The dynamics of metastability regions for different
values of Q is studied numerically.Comment: 15 pages, 6 figures, with correction
Theory of finite temperature crossovers near quantum critical points close to, or above, their upper-critical dimension
A systematic method for the computation of finite temperature () crossover
functions near quantum critical points close to, or above, their upper-critical
dimension is devised. We describe the physics of the various regions in the
and critical tuning parameter () plane. The quantum critical point is at
, , and in many cases there is a line of finite temperature
transitions at , with . For the relativistic,
-component continuum quantum field theory (which describes lattice
quantum rotor () and transverse field Ising () models) the upper
critical dimension is , and for , is the control
parameter over the entire phase diagram. In the region , we obtain an expansion for coupling constants which then are
input as arguments of known {\em classical, tricritical,} crossover functions.
In the high region of the continuum theory, an expansion in integer powers
of , modulo powers of , holds for all
thermodynamic observables, static correlators, and dynamic properties at all
Matsubara frequencies; for the imaginary part of correlators at real
frequencies (), the perturbative expansion describes
quantum relaxation at or larger, but fails for or smaller. An important principle,
underlying the whole calculation, is the analyticity of all observables as
functions of at , for ; indeed, analytic continuation in is
used to obtain results in a portion of the phase diagram. Our method also
applies to a large class of other quantum critical points and their associated
continuum quantum field theories.Comment: 36 pages, 4 eps figure
Numerical comparison of two approaches for the study of phase transitions in small systems
We compare two recently proposed methods for the characterization of phase
transitions in small systems. The validity and usefulness of these approaches
are studied for the case of the q=4 and q=5 Potts model, i.e. systems where a
thermodynamic limit and exact results exist. Guided by this analysis we discuss
then the helix-coil transition in polyalanine, an example of structural
transitions in biological molecules.Comment: 16 pages and 7 figure
Double-beta decay of Te to the first 0 excited state of Xe with CUORICINO
The CUORICINO experiment was an array of 62 TeO single-crystal
bolometers with a total Te mass of kg. The experiment finished
in 2008 after more than 3 years of active operating time. Searches for both
and double-beta decay to the first excited state in
Xe were performed by studying different coincidence scenarios. The
analysis was based on data representing a total exposure of
N(Te)t=y. No evidence for a signal was
found. The resulting lower limits on the half lives are y (90% C.L.), and
y (90%
C.L.).Comment: 6 pages, 4 figure
The development, design, testing, refinement, simulation and application of an evaluation framework for communities of practice and social-professional networks
Background. Communities of practice and social-professional networks are generally considered to enhance workplace experience and enable organizational success. However, despite the remarkable growth in interest in the role of collaborating structures in a range of industries, there is a paucity of empirical research to support this view. Nor is there a convincing model for their systematic evaluation, despite the significant potential benefits in answering the core question: how well do groups of professionals work together and how could they be organised to work together more effectively? This research project will produce a rigorous evaluation methodology and deliver supporting tools for the benefit of researchers, policymakers, practitioners and consumers within the health system and other sectors. Given the prevalence and importance of communities of practice and social networks, and the extent of investments in them, this project represents a scientific innovation of national and international significance. Methods and design. Working in four conceptual phases the project will employ a combination of qualitative and quantitative methods to develop, design, field-test, refine and finalise an evaluation framework. Once available the framework will be used to evaluate simulated, and then later existing, health care communities of practice and social-professional networks to assess their effectiveness in achieving desired outcomes. Peak stakeholder groups have agreed to involve a wide range of members and participant organisations, and will facilitate access to various policy, managerial and clinical networks. Discussion. Given its scope and size, the project represents a valuable opportunity to achieve breakthroughs at two levels; firstly, by introducing novel and innovative aims and methods into the social research process and, secondly, through the resulting evaluation framework and tools. We anticipate valuable outcomes in the improved understanding of organisational performance and delivery of care. The project's wider appeal lies in transferring this understanding to other health jurisdictions and to other industries and sectors, both nationally and internationally. This means not merely publishing the results, but contextually interpreting them, and translating them to advance the knowledge base and enable widespread institutional and organisational application
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