Remotely piloted LTA vehicle for surveillance

Various aspects of a remotely piloted mini-LTA vehicle for surveillance, monitoring and measurement for civilian and military applications are considered. Applications, operations and economics are discussed

Shape of a liquid front upon dewetting

We examine the profile of a liquid front of a film that is dewetting a solid substrate. Since volume is conserved, the material that once covered the substrate is accumulated in a rim close to the three phase contact line. Theoretically, such a profile of a Newtonian liquid resembles an exponentially decaying harmonic oscillation that relaxes into the prepared film thickness. For the first time, we were able to observe this behavior experimentally. A non-Newtonian liquid - a polymer melt - however, behaves differently. Here, viscoelastic properties come into play. We will demonstrate that by analyzing the shape of the rim profile. On a nm scale, we gain access to the rheology of a non-Newtonian liquid.Comment: 4 pages, 4 figure

Band structure of helimagnons in MnSi resolved by inelastic neutron scattering

A magnetic helix realizes a one-dimensional magnetic crystal with a period given by the pitch length $\lambda_h$. Its spin-wave excitations -- the helimagnons -- experience Bragg scattering off this periodicity leading to gaps in the spectrum that inhibit their propagation along the pitch direction. Using high-resolution inelastic neutron scattering the resulting band structure of helimagnons was resolved by preparing a single crystal of MnSi in a single magnetic-helix domain. At least five helimagnon bands could be identified that cover the crossover from flat bands at low energies with helimagnons basically localized along the pitch direction to dispersing bands at higher energies. In the low-energy limit, we find the helimagnon spectrum to be determined by a universal, parameter-free theory. Taking into account corrections to this low-energy theory, quantitative agreement is obtained in the entire energy range studied with the help of a single fitting parameter.Comment: 5 pages, 3 figures; (v2) slight modifications, published versio

Slow Conduction in the Border Zones of Patchy Fibrosis Stabilizes the Drivers for Atrial Fibrillation: Insights from Multi-Scale Human Atrial Modeling

Introduction: The genesis of atrial fibrillation (AF) and success of AF ablation therapy have been strongly linked with atrial fibrosis. Increasing evidence suggests that patient-specific distributions of fibrosis may determine the locations of electrical drivers (rotors) sustaining AF, but the underlying mechanisms are incompletely understood. This study aims to elucidate a missing mechanistic link between patient-specific fibrosis distributions and AF drivers. Methods: 3D atrial models integrated human atrial geometry, rule-based fiber orientation, region-specific electrophysiology, and AF-induced ionic remodeling. A novel detailed model for an atrial fibroblast was developed, and effects of myocyte-fibroblast (M-F) coupling were explored at single-cell, 1D tissue and 3D atria levels. Left atrial LGE MRI datasets from 3 chronic AF patients were segmented to provide the patient-specific distributions of fibrosis. The data was non-linearly registered and mapped to the 3D atria model. Six distinctive fibrosis levels (0–healthy tissue, 5–dense fibrosis) were identified based on LGE MRI intensity and modeled as progressively increasing M-F coupling and decreasing atrial tissue coupling. Uniform 3D atrial model with diffuse (level 2) fibrosis was considered for comparison. Results: In single cells and tissue, the largest effect of atrial M-F coupling was on the myocyte resting membrane potential, leading to partial inactivation of sodium current and reduction of conduction velocity (CV). In the 3D atria, further to the M-F coupling, effects of fibrosis on tissue coupling greatly reduce atrial CV. AF was initiated by fast pacing in each 3D model with either uniform or patient-specific fibrosis. High variation in fibrosis distributions between the models resulted in varying complexity of AF, with several drivers emerging. In the diffuse fibrosis models, waves randomly meandered through the atria, whereas in each the patient-specific models, rotors stabilized in fibrotic regions. The rotors propagated slowly around the border zones of patchy fibrosis (levels 3–4), failing to spread into inner areas of dense fibrosis. Conclusion: Rotors stabilize in the border zones of patchy fibrosis in 3D atria, where slow conduction enable the development of circuits within relatively small regions. Our results can provide a mechanistic explanation for the clinical efficacy of ablation around fibrotic regions

Комплекс геофизических исследований скважин с целью определения коллекторских свойств палеозойского резервуара на Герасимовском месторождении (Томская область)

Изучение геологического строения месторождения и анализ ранее проведенных геофизических исследований в скважинах Герасимовского месторождения Томской области позволил построить физико-геологическую модель пласта М нефтегазоносного горизонта зоны контакта. В проектном разделе представлено обоснование заложения глубокой скважины и определен комплекс геофизических методов исследования для решения геологических задач. Рассмотрена методика проведения работ и используемая аппаратура. Рассчитана стоимость затрат на проведение проектных работ и даны рекомендации по минимизации воздействия их на человека и окружающую среду.The study of the geological structure of the field and the analysis of previously conducted geophysical studies in the wells of the Gerasimovskoye field of the Tomsk region made it possible to build a physical and geological model of the reservoir M of the oil and gas horizon of the contact zone. The project section presents the rationale for laying a deep well and defines a set of geophysical research methods to solve geological problems. The technique of work and the equipment used are considered. The cost of design work was calculated and recommendations were made to minimize their impact on humans and the environment

Thickness-dependent spontaneous dewetting morphology of ultrathin Ag films

We show here that the morphological pathway of spontaneous dewetting of ultrathin Ag films on SiO2 under nanosecond laser melting is found to be film thickness dependent. For films with thickness h between 2 <= h <= 9.5 nm, the morphology during the intermediate stages of dewetting consisted of bicontinuous structures. For films 11.5 <= h <= 20 nm, the intermediate stages consisted of regularly-sized holes. Measurement of the characteristic length scales for different stages of dewetting as a function of film thickness showed a systematic increase, which is consistent with the spinodal dewetting instability over the entire thickness range investigated. This change in morphology with thickness is consistent with observations made previously for polymer films [A. Sharma et al, Phys. Rev. Lett., v81, pp3463 (1998); R. Seemann et al, J. Phys. Cond. Matt., v13, pp4925, (2001)]. Based on the behavior of free energy curvature that incorporates intermolecular forces, we have estimated the morphological transition thickness for the intermolecular forces for Ag on SiO2 . The theory predictions agree well with observations for Ag. These results show that it is possible to form a variety of complex Ag nanomorphologies in a consistent manner, which could be useful in optical applications of Ag surfaces, such as in surface enhanced Raman sensing.Comment: 20 pages, 5 figure

Eur J Human Genet

Heterozygous missense mutations in the serine-threonine kinase receptor BMPR1B result typically in brachydactyly type A2 (BDA2), whereas mutations in the corresponding ligand GDF5 cause brachydactyly type C (BDC). Mutations in the GDF inhibitor Noggin (NOG) or activating mutations in GDF5 cause proximal symphalangism (SYM1). Here, we describe a novel mutation in BMPR1B (R486Q) that is associated with either BDA2 or a BDC/SYM1-like phenotype. Functional investigations of the R486Q mutation were performed and compared with the previously reported BDA2-causing mutation R486W and WT BMPR1B. Overexpression of the mutant receptors in chicken micromass cultures resulted in a strong inhibition of chondrogenesis with the R486Q mutant, showing a stronger effect than the R486W mutant. To investigate the consequences of the BMPR1B mutations on the intracellular signal transduction, we used stably transfected C2C12 cells and measured the activity of SMAD-dependent and SMAD-independent pathways. SMAD activation after stimulation with GDF5 was suppressed in both mutants. Alkaline phosphatase induction showed an almost complete loss of activation by both mutants. Our data extend the previously known mutational and phenotypic spectrum associated with mutations in BMPR1B. Disturbances of NOG-GDF5-BMPR1B signaling cascade can result in similar clinical manifestations depending on the quantitative effect and mode of action of the specific mutations within the same functional pathway

Dewetting of thin polymer films near the glass transition

Dewetting of ultra-thin polymer films near the glass transition exhibits unexpected front morphologies [G. Reiter, Phys. Rev. Lett., 87, 186101 (2001)]. We present here the first theoretical attempt to understand these features, focusing on the shear-thinning behaviour of these films. We analyse the profile of the dewetting film, and characterize the time evolution of the dry region radius, $R_{d}(t)$, and of the rim height, $h_{m}(t)$. After a transient time depending on the initial thickness, $h_{m}(t)$ grows like $\sqrt{t}$ while $R_{d}(t)$ increases like $\exp{(\sqrt{t})}$. Different regimes of growth are expected, depending on the initial film thickness and experimental time range.Comment: 4 pages, 5 figures Revised version, published in Physical Review Letters: F. Saulnier, E. Raphael and P.-G. de Gennes, Phys. Rev. Lett. 88, 196101 (2002

Cardiac cell modelling: Observations from the heart of the cardiac physiome project

In this manuscript we review the state of cardiac cell modelling in the context of international initiatives such as the IUPS Physiome and Virtual Physiological Human Projects, which aim to integrate computational models across scales and physics. In particular we focus on the relationship between experimental data and model parameterisation across a range of model types and cellular physiological systems. Finally, in the context of parameter identification and model reuse within the Cardiac Physiome, we suggest some future priority areas for this field