6,404 research outputs found
Classical Robustness of Quantum Unravellings
We introduce three measures which quantify the degree to which quantum
systems possess the robustness exhibited by classical systems when subjected to
continuous observation. Using these we show that for a fixed environmental
interaction the level of robustness depends on the measurement strategy, or
unravelling, and that no single strategy is maximally robust in all ways.Comment: 8 Pages, 2 figures, Version 2. Minor changes to wording for
clarification and some references added. Accepted for publication in
Europhysics Letter
Computational Design of Chemical Nanosensors: Metal Doped Carbon Nanotubes
We use computational screening to systematically investigate the use of
transition metal doped carbon nanotubes for chemical gas sensing. For a set of
relevant target molecules (CO, NH3, H2S) and the main components of air (N2,
O2, H2O), we calculate the binding energy and change in conductance upon
adsorption on a metal atom occupying a vacancy of a (6,6) carbon nanotube.
Based on these descriptors, we identify the most promising dopant candidates
for detection of a given target molecule. From the fractional coverage of the
metal sites in thermal equilibrium with air, we estimate the change in the
nanotube resistance per doping site as a function of the target molecule
concentration assuming charge transport in the diffusive regime. Our analysis
points to Ni-doped nanotubes as candidates for CO sensors working under typical
atmospheric conditions
Bosonic Reduction of Susy Generalized Harry Dym Equation
In this paper we construct the two component supersymmetric generalized Harry
Dym equation which is integrable and study various properties of this model in
the bosonic limit. In particular, in the bosonic limit we obtain a new
integrable system which, under a hodograph transformation, reduces to a coupled
three component system. We show how the Hamiltonian structure transforms under
a hodograph transformation and study the properties of the model under a
further reduction to a two component system. We find a third Hamiltonian
structure for this system (which has been shown earlier to be a bi-Hamiltonian
system) making this a genuinely tri-Hamiltonian system. The connection of this
system to the modified dispersive water wave equation is clarified. We also
study various properties in the dispersionless limit of our model.Comment: 21 page
QUANTIFYING CRITICAL FEATURES OF UNDERWATER STROKE TECHNIQUE IN FREESTYLE SWIMMING
The purpose of this study was to establish methods for accurately quantifying the time of entry, catch and release in freestyle swimming. The methods allow ready data collection, digitising and analysis without recourse to expensive cameras and diglising equipment thereby enabling analysis by coaches as well as biomechanists. Interpolation procedures to improve the accuracy of estimating the time of occurrence of the events were developed
Rotational Feshbach Resonances in Ultracold Molecular Collisions
In collisions at ultralow temperatures, molecules will possess Feshbach
resonances, foreign to ultracold atoms, whose virtual excited states consist of
rotations of the molecules. We estimate the mean spacing and mean widths of
these resonant states, exploiting the fact the molecular collisions at low
energy display chaotic motion. As examples, we consider the experimentally
relevant molecules O_2, OH, and PbO. The density of s-wave resonant states for
these species is quite high, implying that a large number of narrow resonant
states will exist.Comment: 4 pages, 2 figure
Partition function of two- and three-dimensional Potts ferromagnets for arbitrary values of q>0
A new algorithm is presented, which allows to calculate numerically the
partition function Z_q of the d-dimensional q-state Potts models for arbitrary
real values q>0 at any given temperature T with high precision. The basic idea
is to measure the distribution of the number of connected components in the
corresponding Fortuin-Kasteleyn representation and to compare with the
distribution of the case q=1 (graph percolation), where the exact result Z_1=1
is known.
As application, d=2 and d=3-dimensional ferromagnetic Potts models are
studied, and the critical values q_c, where the transition changes from second
to first order, are determined. Large systems of sizes N=1000^2 respectively
N=100^3 are treated. The critical value q_c(d=2)=4 is confirmed and
q_c(d=3)=2.35(5) is found.Comment: 4 pages, 4 figures, RevTe
Pinning of quantized vortices in helium drop by dopant atoms and molecules
Using a density functional method, we investigate the properties of liquid
4He droplets doped with atoms (Ne and Xe) and molecules (SF_6 and HCN). We
consider the case of droplets having a quantized vortex pinned to the dopant. A
liquid drop formula is proposed that accurately describes the total energy of
the complex and allows one to extrapolate the density functional results to
large N. For a given impurity, we find that the formation of a
dopant+vortex+4He_N complex is energetically favored below a critical size
N_cr. Our result support the possibility to observe quantized vortices in
helium droplets by means of spectroscopic techniques.Comment: Typeset using Revtex, 3 pages and 5 figures (4 Postscript, 1 jpeg
Molecular formations in ultracold mixtures of interacting and noninteracting atomic gases
Atom-molecule equilibrium for molecular formation processes is discussed for
boson-fermion, fermion-fermion, and boson-boson mixtures of ultracold atomic
gases in the framework of quasichemical equilibrium theory. After presentation
of the general formulation, zero-temperature phase diagrams of the
atom-molecule equilibrium states are calculated analytically; molecular, mixed,
and dissociated phases are shown to appear for the change of the binding energy
of the molecules. The temperature dependences of the atom or molecule densities
are calculated numerically, and finite-temperature phase structures are
obtained of the atom-molecule equilibrium in the mixtures. The transition
temperatures of the atom or molecule Bose-Einstein condensations are also
evaluated from these results. Quantum-statistical deviations of the law of mass
action in atom-molecule equilibrium, which should be satisfied in mixtures of
classical Maxwell-Boltzmann gases, are calculated, and the difference in the
different types of quantum-statistical effects is clarified. Mean-field
calculations with interparticle interactions (atom-atom, atom-molecule, and
molecule-molecule) are formulated, where interaction effects are found to give
the linear density-dependent term in the effective molecular binding energies.
This method is applied to calculations of zero-temperature phase diagrams,
where new phases with coexisting local-equilibrium states are shown to appear
in the case of strongly repulsive interactions.Comment: 35 pages, 14 figure
British Association for Biological Anthropology and Osteoarchaeology: Equality, Diversity and Inclusion Race Equality Review
Racism continues to be widespread, subtle and often ignored or selectively attended to within organisations. This review sought to evaluate the British Association for Biological Anthropology and Osteoarchaeology (BABAO)’s existing race equality practices, to further support its movement towards becoming an antiracist organisation. The review arose from a commitment by BABAO to interrogate its current structures and redress problematic cultures within the organisation, following a member of colour expressing concerns. In itself, this provides an encouraging example both of the reflexivity of the organisation and the power of a single voice.
Through focus groups and surveys, insights were gained with regards to the organisational culture and in response to issues concerning equality, diversity and inclusion (EDI), particularly regarding the need for BABAO to become a more racially literate organisation. The review attempted to
glean members’ understanding of anti-racism and how some cultures within the organisation may be racially exclusive or marginalising. In addition to this, the reviewers engaged with stakeholders about where areas could be improved within BABAO in continuing their work towards becoming
a racially cognizant organisation. Responses gleaned from the focus groups and survey questionnaire distributed to members revealed that BABAO as an organisation has made some
tentative first steps towards race equality, but has some way to go. The paucity of Black, Asian and Minority Ethnic members made gaining perspectives a challenge in relation to experiences of racial discrimination. In itself, this is an indicator that inclusion is an area for growth and reflection. Other key findings included issues with reporting structures and governance processes, with a need for strong and courageous leadership to drive forward conversations around race and racism; a need for training and work to improve racial literacy of the organisation and its members; and a lack of engagement and participation from current members in EDI issues. Nevertheless, the review also indicated that the organisation has made significant strides towards establishing anti-racist practices and are working diligently to engage all members in this endeavour. To this end, the conclusions and recommendations provided aim to
enhance current action and further enable BABAO to achieve an anti-racist, inclusive organisational culture.Based on the considerations outlined throughout the report, there were twenty-seven recommendations made. They reflect the need to build a foundation of awareness, understanding and safety upon which to develop a culture of learning, reflection and shared, collective action. High-level recommendations are synthesised below, with further detail in the body of the report
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