339 research outputs found
A Qualitative Study of How Children Experience and Live with Long QT Syndrome
Long QT syndrome (LQTS) is an inherited and potentially fatal disorder affecting approximately 1 in 2,000 people. Children often experience anxiety and a sense of loss of control as they try to manage the medical, social, and psychological stress that accompanies being diagnosed with LQTS. The present study utilized a qualitative research design to examine how children experience and live with long QT syndrome. Semistructured interviews were conducted with eight children between the ages of 7 to 12 who were diagnosed with LQTS. This period in a childâs life is very important for developing social skills and self-esteem as peers and teachers become more important to the child. Themes that emerged involved treatment, relationships, and social connectedness. Children communicated aspects of treatment that were important to them, such as the doctor-patient relationship, stress test, medication, going to the hospital, and lifestyle restrictions. Parental and peer relationships were also explored with regard to how much information should be known by the child, perceptions of worry, confiding in friends or keeping it private, and values of importance in a peer relationship. The children voiced fears about not being accepted and being treated differently and more specific fears, including people knowing about the diagnosis, having to answer questions about the heart monitor, and experiencing feelings of sadness and loneliness. The âFive Pillars of Adaptation for Long QT Syndromeâ born from this research are developmental level and self-esteem, peer and social relationships, parental support, social problem-solving, and treatment and resources. They provide the fundamental elements though which we can learn how a child lives with long QT syndrome
Going Green: Crime Prevention Through Environmental Design In Dubai
Crime Prevention Through Environmental Design (CPTED) is a 21st century approach to integrating various methods of crime-reducing physical and perceived security enhancement measures into a given environment. A taxonomy of CPTED measures was developed based on broader patterns identified by a guiding text in the field, 21st Century Security and CPTED (Atlas, 2008). This taxonomy was utilized as a rubric for field observations of CPTED instances in Dubai, U.A.E. Photographic record and 13 points of data were collected for each instance of CPTED over the course of 26 days, resulting in a matrix of over 700 data points. The data was then used to assess whether any correlation exists between the CPTED measures which are perceived as positively integrated with their surrounding built environments versus those which are perceived as poorly integrated with their built environments. Findings from this study suggest that CPTED measures which incorporate elements of greenery are perceived as more natural and seamlessly integrated with their built environments than those without greenery, despite both being artificially constructe
On the Chemical Mixing Induced by Internal Gravity Waves
Detailed modeling of stellar evolution requires a better understanding of the (magneto)hydrodynamic processes that mix chemical elements and transport angular momentum. Understanding these processes is crucial if we are to accurately interpret observations of chemical abundance anomalies, surface rotation measurements, and asteroseismic data. Here, we use two-dimensional hydrodynamic simulations of the generation and propagation of internal gravity waves in an intermediate-mass star to measure the chemical mixing induced by these waves. We show that such mixing can generally be treated as a diffusive process. We then show that the local diffusion coefficient does not depend on the local fluid velocity, but rather on the wave amplitude. We then use these findings to provide a simple parameterization for this diffusion, which can be incorporated into stellar evolution codes and tested against observations
Comment on âWhat Determines the Static Force Chains in Stressed Granular Media?â
Comment on O. Gendelman, Y. G. Pollack, I. Procaccia, S. Sengupta, and J.
Zylberg, Physical Review Letters 116, 078001 (2016).Comment: 1 pag
Shallow two-component gravity-driven flows with vertical variation
Gravity-driven geophysical mass flows often consist of a heterogeneous fluid-solid mixture. The complex interplay between the components leads to phenomena such as lateral levee formation in avalanches, or a granular front and an excess fluid pore pressure in debris flows. These effects are very important for predicting runout and the forces on structures, yet they are only partially represented in simplified shallow flow theories, since rearrangement of the mixture composition perpendicular to the main flow direction is neglected. In realistic flows, however, rheological properties and effective basal drag may depend strongly on the relative concentration of the components. We address this problem and present a depth-averaged model for shallow mixtures that explicitly allows for rearrangement in this direction. In particular we consider a fluid-solid mixture that experiences bulk horizontal motion, as well as internal sedimentation and resuspension of the particles, and therefore resembles the case of a debris flow. Starting from general mixture theory we derive bulk balance laws and an evolution equation for the particle concentration. Depth-integration yields a shallow mixture flow model in terms of bulk mass, depth-averaged particle concentration, the particle vertical centre of mass and the depth-averaged velocity. This new equation in this model for the particle vertical centre of mass is derived by taking the first moment, with respect to the vertical coordinate, of the particle mass conservation equation. Our approach does not make the Boussinesq approximation and results in additional terms coupling the momentum flux to the vertical centre of mass. The system is hyperbolic and reduces to the shallow-water equations in the homogeneous limit of a pure fluid or perfect mixing. We highlight the effects of sedimentation on resuspension and finally present a simple friction feedback which qualitatively resembles a large-scale experimental debris flow data set acquired at the Illgraben, Switzerlan
Comparing Flow Thresholds and Dynamics for Oscillating and Inclined Granular Layers
The onset and dynamics of flow in shallow horizontally oscillating granular layers are studied as a function of the depth of the layer and imposed acceleration. Measurements of the flow velocity made from the top and side are presented in the frame of reference of the container. As is also found for avalanches of inclined layers, the thresholds for starting and stopping of flow are slightly different. The variation with depth of the starting acceleration Îstart for the oscillating layer is similar to the corresponding variation of the tangent of the starting angle tan(Îstart) for avalanches in the same container at low frequencies, but deviates as the frequency is increased. However, the threshold behavior depends significantly on the measurement protocol. Just above Îstart, the motion decays with time as the material reorganizes over a minute or so, causing the apparent threshold to increase. Furthermore, the rms velocity as a function of acceleration rises more sharply above the starting threshold if the first minute or so of excitation is discarded. Once excited, the rheology of the material is found to vary in time during the cycle in surprising ways. If the maximum inertial force (proportional to the container acceleration amplitude) is slightly higher than that required to produce flow, the flow velocity grows as soon as the inertial force exceeds zero in each cycle, but jamming occurs long before the inertial force returns to zero. At higher Î, the motion is fluidlike over the entire cycle. However, the fraction of the cycle during which the layer is mobile is typically far higher than what one would predict from static considerations or the behavior of the inclined layer. Finally, we consider the flow profiles as a function of both the transverse distance across the cell at the free surface and also as a function of the vertical coordinate in the boundary layer near the sidewall. These profiles have time-dependent shapes and are therefore significantly different from profiles previously measured for avalanche flows
The dynamics of surges in the 3 February 2015 avalanches in Vallee de la Sionne
Five avalanches were artificially released at the VallĂ©e de la Sionne test site in the west of Switzerland on 3 February 2015 and recorded by the GEOphysical flow dynamics using pulsed Doppler radAR Mark 3 radar system. The radar beam penetrates the dilute powder cloud and measures reflections from the underlying denser avalanche features allowing the tracking of the flow at 111 Hz with 0.75 m downslope resolution. The data show that the avalanches contain many internal surges. The large or âmajorâ surges originate from the secondary release of slabs. These slabs can each contain more mass than the initial release, and thus can greatly affect the flow dynamics, by unevenly distributing the mass. The small or âminorâ surges appear to be a roll wave-like instability, and these can greatly influence the front dynamics as they can repeatedly overtake the leading edge. We analyzed the friction acting on the fronts of minor surges using a Voellmy-like, simple one-dimensional model with frictional resistance and velocity-squared drag. This model fits the data of the overall velocity, but it cannot capture the dynamics and especially the slowing of the minor surges, which requires dramatically varying effective friction. Our findings suggest that current avalanche models based on Voellmy-like friction laws do not accurately describe the physics of the intermittent frontal region of large mixed avalanches. We suggest that these data can only be explained by changes in the snow surface, such as the entrainment of the upper snow layers and the smoothing by earlier flow fronts
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Mathematical and biological modelling of RNA secondary structure and its effects on gene expression.
Secondary structures within the 5' untranslated regions of messenger RNAs can have profound effects on the efficiency of translation of their messages and thereby on gene expression. Consequently they can act as important regulatory motifs in both physiological and pathological settings. Current approaches to predicting the secondary structure of these RNA sequences find the structure with the global-minimum free energy. However, since RNA folds progressively from the 5' end when synthesised or released from the translational machinery, this may not be the most probable structure. We discuss secondary structure prediction based on local-minimisation of free energy with thermodynamic fluctuations as nucleotides are added to the 3' end and show that these can result in different secondary structures. We also discuss approaches for studying the extent of the translational inhibition specified by structures within the 5' untranslated region.Peer Reviewe
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