4,761 research outputs found
Extending electron orbital precession to the molecular case: Can orbital alignment be used to observe wavepacket dynamics?
The complexity of ultrafast molecular photoionization presents an obstacle to
the modelling of pump-probe experiments. Here, a simple optimized model of
atomic rubidium is combined with a molecular dynamics model to predict
quantitatively the results of a pump-probe experiment in which long range
rubidium dimers are first excited, then ionized after a variable delay. The
method is illustrated by the outline of two proposed feasible experiments and
the calculation of their outcomes. Both of these proposals use Feshbach 87Rb2
molecules. We show that long-range molecular pump-probe experiments should
observe spin-orbit precession given a suitable pump-pulse, and that the
associated high-frequency beat signal in the ionization probability decays
after a few tens of picoseconds. If the molecule was to be excited to only a
single fine structure state state, then a low-frequency oscillation in the
internuclear separation would be detectable through the timedependent
ionization cross section, giving a mechanism that would enable observation of
coherent vibrational motion in this molecule.Comment: 9 pages, 10 figures, PRA submissio
Veterinary practitioners’ selection of diagnostic tests for the primary evaluation of colic in the horse
The aim of this study was to survey veterinary practitioners’ selection of diagnostic tests for horses with clinical signs of abdominal pain. A questionnaire was distributed to veterinary surgeons involved in the primary evaluation of horses with abdominal pain, including the respondent's demographics, selection of diagnostic tests and factors affecting decision-making. Data analysis included descriptive analysis, categorisation of free text and simple univariable correlations to explore the relationships between independent variables and the relative self-estimated frequency that diagnostic tests were performed. A total of 228 responses were analysed. Participants worked in mixed practice (55.7 per cent), first opinion equine (22.8 per cent), first and second opinion equine (17.9 per cent) and referral practice (3.1 per cent). The majority (48.2 per cent, 105/218) were very confident managing a colic case (confidence level 4/5). The most frequently used diagnostic tests were ‘response to analgesia’ (87.2±24.0 per cent cases), rectal examination (75.9±21.2 per cent) and nasogastric intubation (43.8±27.6 per cent). Approach varied between practitioners, and for all diagnostic tests with frequency of use ranging from 0 to 100 per cent of cases. ‘Risk to personal safety’ was the most common reason for not using rectal examination. Practitioner's opinion of their confidence level in managing a colic case was associated with how frequently they used different diagnostic tests. There was marked variation in practitioners’ approaches, highlighting the need for further evidence to support decision-making
A Tale of Two Animats: What does it take to have goals?
What does it take for a system, biological or not, to have goals? Here, this
question is approached in the context of in silico artificial evolution. By
examining the informational and causal properties of artificial organisms
('animats') controlled by small, adaptive neural networks (Markov Brains), this
essay discusses necessary requirements for intrinsic information, autonomy, and
meaning. The focus lies on comparing two types of Markov Brains that evolved in
the same simple environment: one with purely feedforward connections between
its elements, the other with an integrated set of elements that causally
constrain each other. While both types of brains 'process' information about
their environment and are equally fit, only the integrated one forms a causally
autonomous entity above a background of external influences. This suggests that
to assess whether goals are meaningful for a system itself, it is important to
understand what the system is, rather than what it does.Comment: This article is a contribution to the FQXi 2016-2017 essay contest
"Wandering Towards a Goal
Administrative Law
This survey updates Professor Levinson\u27s 1975 article on the Florida Administrative Procedure Act. The survey examines and reports all appellate decisions, attorney general opinions and 1976 amendments. Collateral to the discussion of the 1976 amendments, the authors focus on and report the results of the first series of amendments enacted in 1975. In addition, a legislatively proposed constitutional amendment, defeated in the last general election, and the implementing bill vetoed by the governor prior to the general election are considered
Penalty finite element approximations of the stationary power- law Stokes problem
Finite element approximations of the stationary power-law Stokes problem using penalty
formulation are considered. A priori error estimates under appropriate smoothness assumptions on the
solutions are established without assuming a discrete version of the BB condition. Numerical solutions
are presented by implementing a nonlinear conjugate gradient metho
Reviewing research evidence and the case of participation in sport and physical recreation by black and minority ethnic communities
The paper addresses the implications of using the process of systematic review in the many areas of leisure where there is a dearth of material that would be admitted into conventional Cochrane Reviews. This raises important questions about what constitutes legitimate knowledge, questions that are of critical import not just to leisure scholars, but to the formulation of policy. The search for certainty in an area that lacks conceptual consensus results in an epistemological imperialism that takes a geocentric form. While clearly, there is a need for good research design whatever the style of research, we contend that the wholesale rejection of insightful research is profligate and foolhardy. A mechanism has to be found to capitalise on good quality research of whatever form. In that search, we draw upon our experience of conducting a review of the material available on participation in sport and physical recreation by people from Black and minority ethnic groups. The paper concludes with a proposal for a more productive review process that makes better use of the full panoply of good quality research available. © 2012 © 2012 Taylor & Francis
Dynamics of gene expression and the regulatory inference problem
From the response to external stimuli to cell division and death, the
dynamics of living cells is based on the expression of specific genes at
specific times. The decision when to express a gene is implemented by the
binding and unbinding of transcription factor molecules to regulatory DNA.
Here, we construct stochastic models of gene expression dynamics and test them
on experimental time-series data of messenger-RNA concentrations. The models
are used to infer biophysical parameters of gene transcription, including the
statistics of transcription factor-DNA binding and the target genes controlled
by a given transcription factor.Comment: revised version to appear in Europhys. Lett., new titl
A pump-probe study of the formation of rubidium molecules by ultrafast photoassociation of ultracold atoms
An experimental pump-probe study of the photoassociative creation of
translationally ultracold rubidium molecules is presented together with
numerical simulations of the process. The formation of loosely bound
excited-state dimers is observed as a first step towards a fully coherent
pump-dump approach to the stabilization of Rb into its lowest ground
vibrational states. The population that contributes to the pump-probe process
is characterized and found to be distinct from a background population of
pre-associated molecules.Comment: Accepted for publication in Phys. Rev. A (10 pages, 9 figures
Climate change adaptation planning and cross-sectoral policy coherence in southern Africa
The post-2015 development agenda requires policy coherence, where achievement
of development goals in one sector does not undermine the achievement of the
goals of another. It also recognises that cross-cutting issues like adaptation
to climate change need to be mainstreamed across multiple sectors. This paper
presents a policy analysis using the cases of Malawi, Tanzania and Zambia. It
analyses the water management and agricultural strategies and approaches
identified in a variety of policies and plans. These include national sector
policies for water and agriculture, National Development Plans, and climate
change policies and strategies, including National Adaptation Programmes of
Action and the Intended Nationally Determined Contributions submitted prior to
the 2015 United Nations Framework Convention on Climate Change Conference of
the Parties. It assesses the extent to which policies are coherent with one
another with regard to their treatment of climate change adaptation using
Qualitative Document Analysis. Findings identify that sector policies show
some degree of cross-thematic coherence, in particular around their
acknowledgement of the importance to address disaster management of floods and
droughts. However, policy statements are typified by a relative lack of
recognition of the need to develop supporting instruments and strategies that
address climate adaptation needs over longer timeframes. Climate change
policies explicitly call for significant investment in adaptation from the
international community. Where coherence between sector and climate policies
and strategies is strongest, the more recent climate policies largely
repackage existing sectoral policy statements. These findings can be
understood in the context of the uncertainty of climate change impacts for the
longer term (for which a wider variety of adaptations are identified),
alongside more event-driven disaster management planning where the impacts are
more immediate and obviously evident. This prioritisation is also linked to
development needs and the short-term nature of political cycles and economic
gain. For climate-resilient policy decision-making to make further headway, we
argue that governments need to embrace cross-sectoral planning more pro-
actively in order to foster greater policy coherence and to deliver more
climate resilient agriculture and water management
From Navas to Kaltoft: The European Court of Justice’s evolving definition of disability and the implications for HIV-positive individuals
This article will examine the definition of disability developed by the European Court of Justice for the purposes of the Employment Equality Directive and examine whether it is sufficient for the purpose of bringing People Living with HIV/AIDS within its scope. The article will argue that in order to adequately protect People Living with HIV/AIDS within the EU from discrimination, the European Court of Justice needs to ensure that a coherent EU wide definition of disability, based fully upon the social model of disability, is adopted. This is necessary in order to ensure adequate protection not only for People Living with HIV/AIDS but for all individuals with disabilities from discrimination throughout the EU. In addition to this central argument, this paper will argue that the lack of a coherent definition of disability grounded in the social model fragments protection for People Living with HIV/AIDS across the EU leading to a number of possible unintended consequences
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