217 research outputs found
Measuring every particle's size from three-dimensional imaging experiments
Often experimentalists study colloidal suspensions that are nominally
monodisperse. In reality these samples have a polydispersity of 4-10%. At the
level of an individual particle, the consequences of this polydispersity are
unknown as it is difficult to measure an individual particle size from
microscopy. We propose a general method to estimate individual particle radii
within a moderately concentrated colloidal suspension observed with confocal
microscopy. We confirm the validity of our method by numerical simulations of
four major systems: random close packing, colloidal gels, nominally
monodisperse dense samples, and nominally binary dense samples. We then apply
our method to experimental data, and demonstrate the utility of this method
with results from four case studies. In the first, we demonstrate that we can
recover the full particle size distribution {\it in situ}. In the second, we
show that accounting for particle size leads to more accurate structural
information in a random close packed sample. In the third, we show that crystal
nucleation occurs in locally monodisperse regions. In the fourth, we show that
particle mobility in a dense sample is correlated to the local volume fraction.Comment: 7 pages, 5 figure
Prioritization of fish communities with a view to conservation and restoration on a large scale European basin, the Loire (France)
The hierarchical organization of important sites for the conservation or the
restoration of fish communities is a great challenge for managers, especially because of
financial or time constraints. In this perspective, we developed a methodology, which is
easy to implement in different locations. Based on the fish assemblage characteristics of
the Loire basin (France), we created a synthetic conservation value index including the
rarity, the conservation status and the species origin. The relationship between this new
synthetic index and the Fish-Based Index allowed us to establish a classification protocol
of the sites along the Loire including fish assemblages to be restored or conserved. Sites
presenting disturbed fish assemblages, a low rarity index, few threatened species, and a
high proportion of non-native species were considered as important for the restoration of
fish biodiversity. These sites were found mainly in areas where the assemblages are
typical of the bream zone, e.g. with a higher number of eurytopic and limnophilic
species. On the contrary, important sites for conservation were defined as having an
important conservation potential (high RI, a lot of threatened species, and few nonnatives
fish species) and an undisturbed fish assemblage similar to the expected community
if habitats are undisturbed. Important sites for conservation were found in the
Loire basin’s medium reaches which host assemblages typical for the grayling and the
barbell zones, e.g. with a higher number of rheophilic species. The synthetic conservation value index could be adapted and completed with other criteria according to
management priorities and capacities
Towards an Integrative Cognitive-Socio-Technical Approach in Health Informatics: Analyzing Technology-Induced Error Involving Health Information Systems to Improve Patient Safety
The purpose of this paper is to argue for an integration of cognitive and socio-technical approaches to assessing the impact of health information systems. Historically, health informatics research has examined the cognitive and socio-technical aspects of health information systems separately. In this paper we argue that evaluations of health information systems should consider aspects related to cognition as well as socio-technical aspects including impact on workflow (i.e. an integrated view). Using examples from the study of technology-induced error in healthcare, we argue for the use of simulations to evaluate the cognitive-socio-technical impacts of health information technology [36]. Implications of clinical simulations and analysis of cognitive-social-technical impacts are discussed within the context of the system development life cycle to improve health information system design, implementation and evaluation
How should health service organizations respond to diversity? A content analysis of six approaches
Background Health care organizations need to be responsive to the needs of increasingly diverse patient populations. We compared the contents of six publicly available approaches to organizational responsiveness to diversity. The central questions addressed in this paper are: what are the most consistently recommended issues for health care organizations to address in order to be responsive to the needs of diverse groups that differ from the majority population? How much consensus is there between various approaches? Methods We purposively sampled six approaches from the US, Australia and Europe and used qualitative textual analysis to categorize the content of each approach into domains (conceptually distinct topic areas) and, within each domain, into dimensions (operationalizations). The resulting classification framework was used for comparative analysis of the content of the six approaches. Results We identified seven domains that were represented in most or all approaches: organizational commitment, empirical evidence on inequalities and needs, a competent and diverse workforce, ensuring access for all users, ensuring responsiveness in care provision, fostering patient and community participation, and actively promoting responsiveness. Variations in the operationalization of these domains related to different scopes, contexts and types of diversity. For example, approaches that focus on ethnic diversity mostly provide recommendations to handle cultural and language differences; approaches that take an intersectional approach and broaden their target population to vulnerable groups in a more general sense also pay attention to factors such as socio-economic status and gender. Conclusions Despite differences in labeling, there is a broad consensus about what health care organizations need to do in order to be responsive to patient diversity. This opens the way to full scale implementation of organizational responsiveness in healthcare and structured evaluation of its effectiveness in improving patient outcomes
Holographic Roberge-Weiss Transitions II: Defect Theories and the Sakai-Sugimoto Model
We extend the work of Aarts et al., including an imaginary chemical potential
for quark number into the Sakai-Sugimoto model and codimension k defect
theories. The phase diagram of these models are a function of three parameters,
the temperature, chemical potential and the asymptotic separation of the
flavour branes, related to a mass for the quarks in the boundary theories. We
compute the phase diagrams and the pressure due to the flavours of the theories
as a function of these parameters and show that there are Roberge-Weiss
transitions in the high temperature phases, chiral symmetry restored for the
Sakai-Sugimoto model and deconfined for the defect models, while at low
temperatures there are no Roberge-Weiss transitions. In all the models we
consider the transitions between low and high temperature phases are first
order, hence the points where they meet the Roberge-Weiss lines are triple
points. The pressure for the defect theories scales in the way we expect from
dimensional analysis while the Sakai-Sugimoto model exhibits unusual scaling.
We show that the models we consider are analytic in \mu^2 when \mu^2 is small.Comment: 39 pages, 12 figures. references added, Sakai-Sugimoto section
revised, version to appear in JHE
Computational Prediction and Molecular Characterization of an Oomycete Effector and the Cognate Arabidopsis Resistance Gene
Hyaloperonospora arabidopsidis (Hpa) is an obligate biotroph oomycete pathogen of the model plant Arabidopsis thaliana and contains a large set of effector proteins that are translocated to the host to exert virulence functions or trigger immune responses. These effectors are characterized by conserved amino-terminal translocation sequences and highly divergent carboxyl-terminal functional domains. The availability of the Hpa genome sequence allowed the computational prediction of effectors and the development of effector delivery systems enabled validation of the predicted effectors in Arabidopsis. In this study, we identified a novel effector ATR39-1 by computational methods, which was found to trigger a resistance response in the Arabidopsis ecotype Weiningen (Wei-0). The allelic variant of this effector, ATR39-2, is not recognized, and two amino acid residues were identified and shown to be critical for this loss of recognition. The resistance protein responsible for recognition of the ATR39-1 effector in Arabidopsis is RPP39 and was identified by map-based cloning. RPP39 is a member of the CC-NBS-LRR family of resistance proteins and requires the signaling gene NDR1 for full activity. Recognition of ATR39-1 in Wei-0 does not inhibit growth of Hpa strains expressing the effector, suggesting complex mechanisms of pathogen evasion of recognition, and is similar to what has been shown in several other cases of plant-oomycete interactions. Identification of this resistance gene/effector pair adds to our knowledge of plant resistance mechanisms and provides the basis for further functional analyses
- …