1,042 research outputs found
Statistical Mechanics of the Chinese Restaurant Process: lack of self-averaging, anomalous finite-size effects and condensation
The Pitman-Yor, or Chinese Restaurant Process, is a stochastic process that
generates distributions following a power-law with exponents lower than two, as
found in a numerous physical, biological, technological and social systems. We
discuss its rich behavior with the tools and viewpoint of statistical
mechanics. We show that this process invariably gives rise to a condensation,
i.e. a distribution dominated by a finite number of classes. We also evaluate
thoroughly the finite-size effects, finding that the lack of stationary state
and self-averaging of the process creates realization-dependent cutoffs and
behavior of the distributions with no equivalent in other statistical
mechanical models.Comment: (5pages, 1 figure
Automated synthesis of radiopharmaceuticals for positron emission tomography: an apparatus for labelling with [11C] methyl iodide (MIASA)
A fully automated apparatus for the routine synthesis and
formulation of short-lived 11C (t1/2 = 20 min) labelled radiopharmaceuticals
for positron emission tomography (PET) has
been developed. [11C]Carbon dioxide is converted to [11C]methyl
iodide, which can be used to label a wide variety of substrates by
methylation at C, N, O, or S electron rich centres. The apparatus,
MIASA (methyl iodide automated synthesis apparatus), was
designed to operate as part of an automated labelling system in a
shielded âhotâ laboratory. The apparatus was designed without the
size constraints of typical instrumentation used in hot cells, although
it is compact where necessary. Ample use of indicators and sensors,
together with compact design of the reaction flasks for small dead
space and efficient evaporation, led to good reliability and
performance. The design of the hardware and software is described
in this paper, together with a preparation of 3-N-[11C]methylspiperone
as a sterile injectable solution in physiological saline
Aerosol chemical composition and distribution during the Pacific Exploratory Mission (PEM) Tropics
Distributions of aerosol-associated soluble ions over much of the South Pacific were determined by sampling from the NASA DC-8 as part of the Pacific Exploratory Mission (PEM) Tropics campaign. The mixing ratios of all ionic species were surprisingly low throughout the free troposphere (2-12 km), despite the pervasive influence from biomass burning plumes advecting over the South Pacific from the west during PEM-Tropics. At the same time, the specific activity of 7Be frequently exceeded 1000 fCi m-3 through much of the depth of the troposphere. These distributions indicate that the plumes must have been efficiently scavenged by precipitation (removing the soluble ions), but that the scavenging must have occurred far upwind of the DC-8 sampling regions (otherwise 7Be activities would also have been low). This inference is supported by large enhancements of HNO3 and carboxylic acids in many of the plumes, as these soluble acidic gases would also be readily scavenged in any precipitation events. Decreasing mixing ratios of NH4 + with altitude in all South Pacific regions sampled provide support for recent suggestions that oceanic emissions of NH3 constitute a significant source far from continents. Our sampling below 2 km reaffirms the latitudinal pattern in the methylsulfonate/non-sea-salt sulfate (MSA/nss SO4 =) molar ratio established through surface-based and shipboard sampling, with values increasing from \u3c0.05 in the tropics to nearly 0.6 at 70°S. However, we also found very high values of this ratio (0.2-0.5) at 10 km altitude above the intertropical convergence zone near 10°N. It appears that wet convective pumping of dimethylsulfide from the tropical marine boundary layer is responsible for the high values of the MSA/nss SO4 = ratio in the tropical upper troposphere. This finding complicates use of this ratio to infer the zonal origin of biogenic S transported long distances. Copyright 1999 by the American Geophysical Union
"How do pilates trained physiotherapists utilize and value pilates exercise for MSK conditions? A qualitative study"
Background
Pilates is a popular exercise therapy approach offering numerous benefits, including muscular strength, flexibility, control, and core stability. Pilates has been widely utilized in the prevention and rehabilitation of a variety of musculoskeletal disorders.
Objectives
The aim of this study was to explore the experiences and opinions of Pilates trained NHS and private practice physiotherapists in the UK, regarding the perceived benefits, risks, delivery and rationale for this exercise method.
Methods
This qualitative study used a selfâdesigned electronic survey to retrieve the views of 30 physiotherapists, who had undertaken formal Pilates Instruction training, recruited by a purposive and snowball sampling method. Questions were either multiple choice or openâended, examined via thematic analysis.
Results
Physiotherapists identified the most important benefits of Pilates as reduction in fearâavoidance, improving bodily awareness and increasing muscular strength. Exercises that promote general movement were highlighted as being particularly useful, with a majority recommending daily practice for optimum benefit. Participants recognized lack of core strength as a key indicator, whereas others criticized excessive focus on this principle.
Conclusions
Physiotherapists identified a range of interâlinked benefits and recognized that Pilates is hugely modifiable. Individualizing exercises can further encourage participation and negate the restriction of some health conditions. NHS and Private Practice Therapists utilize Pilates in a similar way, although rationales for its use may differ, as the justification for Pilates exercise may be evolving. Pilates appears a valuable methodology in the NHS, which can help patients engage with activity
A chemotactic-based model for spatial activity recognition
Spatial activity recognition in everyday environments is particularly challenging due to noise incorporated during video-tracking. We address the noise issue of spatial recognition with a biologically inspired chemotactic model that is capable of handling noisy data. The model is based on bacterial chemotaxis, a process that allows bacteria to survive by changing motile behaviour in relation to environmental dynamics. Using chemotactic principles, we propose the chemotactic model and evaluate its classification performance in a smart house environment. The model exhibits high classification accuracy (99%) with a diverse 10 class activity dataset and outperforms the discrete hidden Markov model (HMM). High accuracy (>89%) is also maintained across small training sets and through incorporation of varying degrees of artificial noise into testing sequences. Importantly, unlike other bottom–up spatial activity recognition models, we show that the chemotactic model is capable of recognizing simple interwoven activities
Epiparasitic plants specialized on arbuscular mycorrhizal fungi
Over 400 non-photosynthetic species from 10 families of vascular plants obtain their carbon from fungi and are thus defined as myco-heterotrophs. Many of these plants are epiparasitic on green plants from which they obtain carbon by 'cheating' shared mycorrhizal fungi. Epiparasitic plants examined to date depend on ectomycorrhizal fungi for carbon transfer and exhibit exceptional specificity for these fungi, but for most myco-heterotrophs neither the identity of the fungi nor the sources of their carbon are known. Because many myco-heterotrophs grow in forests dominated by plants associated with arbuscular mycorrhizal fungi (AMF; phylum Glomeromycota), we proposed that epiparasitism would occur also between plants linked by AMF. On a global scale AMF form the most widespread mycorrhizae, thus the ability of plants to cheat this symbiosis would be highly significant. We analysed mycorrhizae from three populations of Arachnitis uniflora (Corsiaceae, Monocotyledonae), five Voyria species and one Voyriella species (Gentianaceae, Dicotyledonae), and neighbouring green plants. Here we show that non-photosynthetic plants associate with AMF and can display the characteristic specificity of epiparasites. This suggests that AMF mediate significant inter-plant carbon transfer in nature
Patient Information Leaflets for Lumbar Spine Surgery: A Missed Opportunity
Background: High-quality patient information is recommended to help reduce procedure-related anxiety and encourage
patients to become active participants in their recovery. The objective of this study was to analyze the quality of patient
information leaflets (PILs) given to National Health Service (NHS) patients ahead of lumbar spine surgery. Methods: The
DISCERN tool was used to evaluate the quality of PILs, sourced from NHS websites. Results: Thirty-two PILs on lumbar
surgery were included. Two (6%) leaflets were considered poor, 13 (41%) were marked as fair, 14 (44%) were of good quality,
and 3 (9%) were scored as excellent. The total mean score was 55 (30-74), which corresponds to good quality. The lowest
scoring questions were sources of information (Q4), balanced/unbiased content (Q6), and explanation of no treatment (Q12).
Conclusions: There is considerable variation in the quality of PILs provided ahead of lumbar spine surgery. The scope for
improvement is clear, and as the move toward patient-centered, evidence-based care continues, it is important that hospital
resources provide recommendations based upon evidence of clinical effectiveness
On the origin of the Boson peak in globular proteins
We study the Boson Peak phenomenology experimentally observed in globular
proteins by means of elastic network models. These models are suitable for an
analytic treatment in the framework of Euclidean Random Matrix theory, whose
predictions can be numerically tested on real proteins structures. We find that
the emergence of the Boson Peak is strictly related to an intrinsic mechanical
instability of the protein, in close similarity to what is thought to happen in
glasses. The biological implications of this conclusion are also discussed by
focusing on a representative case study.Comment: Proceedings of the X International Workshop on Disordered Systems,
Molveno (2006
Social presence and dishonesty in retail
Self-service checkouts (SCOs) in retail can benefit consumers and retailers, providing control and autonomy to shoppers independent from staff, together with reduced queuing times. Recent research indicates that the absence of staff may provide the opportunity for consumers to behave dishonestly, consistent with a perceived lack of social presence. This study examined whether a social presence in the form of various instantiations of embodied, visual, humanlike SCO interface agents had an effect on opportunistic behaviour. Using a simulated SCO scenario, participants experienced various dilemmas in which they could financially benefit themselves undeservedly. We hypothesised that a humanlike social presence integrated within the checkout screen would receive more attention and result in fewer instances of dishonesty compared to a less humanlike agent. This was partially supported by the results. The findings contribute to the theoretical framework in social presence research. We concluded that companies adopting self-service technology may consider the implementation of social presence in technology applications to support ethical consumer behaviour, but that more research is required to explore the mixed findings in the current study.<br/
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