Multiscale models of colloidal dispersion of particles in nematic liquid crystals

We use homogenization theory to develop a multiscale model of colloidal dispersion of particles in nematic liquid crystals under weak-anchoring conditions. We validate the model by comparing it with simulations by using the Landau–de Gennes free energy and show that the agreement is excellent. We then use the multiscale model to study the effect that particle anisotropy has on the liquid crystal: spherically symmetric particles always reduce the effective elastic constant. Asymmetric particles introduce an effective alignment field that can increase the Fredericks threshold and decrease the switch-off time

A General Framework for Recursive Decompositions of Unitary Quantum Evolutions

Decompositions of the unitary group U(n) are useful tools in quantum information theory as they allow one to decompose unitary evolutions into local evolutions and evolutions causing entanglement. Several recursive decompositions have been proposed in the literature to express unitary operators as products of simple operators with properties relevant in entanglement dynamics. In this paper, using the concept of grading of a Lie algebra, we cast these decompositions in a unifying scheme and show how new recursive decompositions can be obtained. In particular, we propose a new recursive decomposition of the unitary operator on $N$ qubits, and we give a numerical example.Comment: 17 pages. To appear in J. Phys. A: Math. Theor. This article replaces our earlier preprint "A Recursive Decomposition of Unitary Operators on N Qubits." The current version provides a general method to generate recursive decompositions of unitary evolutions. Several decompositions obtained before are shown to be as a special case of this general procedur

A pediatric digital storytelling system for third year medical students: The Virtual Pediatric Patients

BACKGROUND: Computer-based patient simulations (CBPS) are common, effective, instructional methods for medical students, but have limitations. The goal of this project was to describe the development of a CBPS designed to overcome some of these limitations and to perform an online evaluation. METHODS: In 1996, patients and families experiencing a common pediatric problem were interviewed, photographed and a chart review completed. A digital storytelling template was developed: 1. patient's story, evaluation and clinical course, 2. problem-based approach to the evaluation, and 3. discussion of disease process. The media was digitized and placed onto the Internet. The digital stories and a 10-question online survey were pilot tested. Online survey responses were collected from 1999–2003. Overall use of the digital stories was measured by computer server logs and by the number of hyperlinks to the CBPS. RESULTS: Eight stories were created using this system. Over 4.5 years, 814,148 digital story pages were read by 362,351 users. Hyperlink citations from other websites to the CBPS were 108. Online survey respondents (N = 393) described the overall quality as excellent or very good (88.4%). The stores were clearly written (92%) at an appropriate level (91.4%). Respondents felt they could begin to evaluate a similar case presentation (95.4%), and would remember the case in the future (91%). CONCLUSIONS: A new type of CBPS, the digital storytelling system, has been developed and evaluated which and appears to be successful in overcoming some of the limitations of earlier CBPS by featuring patient's stories in their own words, by focusing on problems rather than diseases, and by having stories that are quick for students to work through

Short report: molecular markers associated with Plasmodium falciparum resistance to sulfadoxine-pyrimethamine in the Democratic Republic of Congo.

Sulfadoxine-pyrimethamine (SP) is the first line antimalarial treatment in the Democratic Republic of Congo. Using polymerase chain reaction, we assessed the prevalence of mutations in the dihydrofolate reductase (dhfr) (codons 108, 51, 59) and dihydropteroate synthase (dhps) (codons 437, 540) genes of Plasmodium falciparum, which have been associated with resistance to pyrimethamine and sulfadoxine, respectively. Four hundred seventy-four patients were sampled in Kilwa (N = 138), Kisangani (N = 112), Boende (N = 106), and Basankusu (N = 118). The proportion of triple mutations dhfr varied between sites but was always > 50%. The proportion of dhps double mutations was < 20%, with some sites as low as 0.9%. A quintuple mutation was present in 12.8% (16/125) samples in Kilwa; 11.9% (13/109) in Kisangani, 2.9% (3/102) in Boende, and 0.9% (1/112) in Basankusu. These results suggest high resistance to pyrimethamine alone or combined with sulfadoxine. Adding artesunate to SP does not seem a valid alternative to the current monotherapy

Spatial targeted vector control is able to reduce malaria prevalence in the highlands of Burundi.

In a highland province of Burundi, indoor residual spraying and long-lasting insecticidal net distribution were targeted in the valley, aiming also to protect the population living on the hilltops. The impact on malaria indicators was assessed, and the potential additional effect of nets evaluated. After the intervention--and compared with the control valleys--children 1-9 years old in the treated valleys had lower risks of malaria infection (odds ratio, OR: 0.55), high parasite density (OR: 0.48), and clinical malaria (OR: 0.57). The impact on malaria prevalence was even higher in infants (OR: 0.14). Using nets did not confer an additional protective effect to spraying. Targeted vector control had a major impact on malaria in the high-risk valleys but not in the less-exposed hilltops. Investment in targeted and regular control measures associated with effective case management should be able to control malaria in the highlands

Thermal optical non-linearity of nematic mesophase enhanced by gold nanoparticles – an experimental and numerical investigation

In this work the mechanisms leading to the enhancement of optical nonlinearity of nematic liquid crystalline material through localized heating by doping the liquid crystals (LCs) with gold nanoparticles (GNPs) are investigated. We present some experimental and theoretical results on the effect of voltage and nanoparticle concentration on the nonlinear response of GNP-LC suspensions. The optical nonlinearity of these systems is characterized by diffraction measurements and the second order nonlinear refractive index, n 2 , is used to compare systems with different configurations and operating conditions. A theoretical model based on heat diffusion that takes into account the intensity and finite size of the incident beam, the nanoparticle concentration dependent absorbance of GNP doped LC systems and the presence of bounding substrates is developed and validated. We use the model to discuss the possibilities of further enhancing the optical nonlinearity

The additional-mode garden of RR Lyrae stars

Space-based photometric missions revealed a surprising abundance of millimagnitude-level additional modes in RR Lyrae stars. The modes that appear in the modulated fundamental-mode (RRab) stars can be ordered into four major categories. Here we present the distribution of these groups in the Petersen diagram, and discuss their characteristics and connections to additional modes observed in other RR Lyrae stars.Comment: 4 pages, 4 figures, proceedings of the Joint TASC2-KASC9-SPACEINN-HELAS8 Conference "Seismology of the Sun and the Distant Stars 2016", to be published in EPJ Wo

Microbiological evidences of methanotriphic activity in the soils of the geothermal area of Pantelleria island (Italy)

Methane plays an important role in the Earth\u2019s atmospheric chemistry and radiative balance being the second most important greenhouse gas after carbon dioxide. Methane is released to the atmosphere by a wide number of sources, both natural and anthropogenic, with the latter being twice as large as the former. It has recently been established that significant amounts of geological methane, produced within the Earth\u2019s crust, are currently released naturally into the atmosphere. Active or recent volcanic/geothermal areas represent one of these sources of geological methane. Microbial oxidation in soils contributes for about 3-9% to the total removal of CH4 from the atmosphere. Recent studies evidenced methanotrophic activity also in soils of volcanic/geothermal areas notwithstanding their harsh environmental conditions (high temperatures, low pH and high concentrations of H2S and NH3). The purpose of our study was to verify the methanotrophic potential and the bacterial diversity of the soils of the main geothermal area of Pantelleria island (Italy). Laboratory incubation experiments with soil samples collected at the main exhalative area showed methane consumption values of up to 9500 ng per g of dry soil per hour while soils collected outside the geothermal area less than 6 ng/g/h. Geothermal soils showed their maximum methane consumption in the shallowest part of the soil profile (0-3 cm) mantaining high values (>100 ng/g/h) at least up to dephts of 15 cm. Furthermore they showed the maximum consumption at about 37\ub0C, showing a still recognizable consumption (>20 ng/g/h) at 80\ub0C, and a positive correlation with the methane concentration in the incubation atmosphere. These results can be considered a clear evidence of the presence of methanotrophs. In order to evaluate the bacterial diversity, soil metagenomic DNA was extracted from Le Favare and analysed using a Temporal Temperature Gradient Electrophoresis (TTGE) analysis of the amplified Bacterial 16S rRNA gene. The amplification of metagenomic DNA with primers targeting Proteobacterial and Verrucomicrobial MMO (methane monooxygenase) genes is in progress. Enrichment cultures on a mineral medium in a CH4-enriched (25%) atmosphere allowed to isolate different strains that are under characterization

Aqueye+: a new ultrafast single photon counter for optical high time resolution astrophysics

Aqueye+ is a new ultrafast optical single photon counter, based on single photon avalanche photodiodes (SPAD) and a 4-fold split-pupil concept. It is a completely revisited version of its predecessor, Aqueye, successfully mounted at the 182 cm Copernicus telescope in Asiago. Here we will present the new technological features implemented on Aqueye+, namely a state of the art timing system, a dedicated and optimized optical train, a high sensitivity and high frame rate field camera and remote control, which will give Aqueye plus much superior performances with respect to its predecessor, unparalleled by any other existing fast photometer. The instrument will host also an optical vorticity module to achieve high performance astronomical coronography and a real time acquisition of atmospheric seeing unit. The present paper describes the instrument and its first performances.Comment: Proceedings of the SPIE, Volume 9504, id. 95040C 14 pp. (2015