Grain size dependence of barchan dune dynamics

The dependence of the barchan dune dynamics on the size of the grains involved is investigated experimentally. Downsized barchan dune slices are observed in a narrow water flow tube. The relaxation time from an initial symmetric triangular heap towards an asymmetric shape attractor increases with dune mass and decreases with grain size. The dune velocity increases with grain size. In contrast, the velocity scaling and the shape of the barchan dune is independent of the size of the grains

Axis formation in annual killifish: Nodal coordinates morphogenesis in absence of Huluwa prepatterning

Axis formation in fish and amphibians is initiated by a prepattern of maternal gene products in the blastula. The embryogenesis of annual killifish challenges prepatterning models because blastomeres disperse and then re-aggregate to form the germ layers and body axes. This dispersion-aggregation process prompts the question how axis determinants such as Huluwa and germ layer inducers such as Nodal function in annual killifish. Here we show in Nothobranchius furzeri that huluwa, the factor thought to break symmetry by stabilizing β-catenin, is a non-functional pseudogene. Nuclear β-catenin is not selectively stabilized on one side of the blastula but accumulates in cells forming the incipient aggregate. Inhibition of Nodal signaling blocks aggregation and disrupts coordinated cell migration, establishing a novel role for this signaling pathway. These results reveal a surprising departure from classic mechanisms of axis formation: canonical Huluwa-mediated prepatterning is dispensable and Nodal coordinates morphogenesis. One Sentence Summary Axis formation in annual killifish relies on Nodal to coordinate cell migration and is independent of Huluwa-mediated prepatterning

Time to first consultation, diagnosis and treatment of TB among patients attending a referral hospital in Northwest, Ethiopia

Background Early detection and treatment of TB is essential for the success of TB control program performance. The aim of this study was to determine the length and analyze predictors of patients’, health systems’ and total delays among patients attending a referral hospital in Bahir Dar, Ethiopia. Methods A cross-sectional study was conducted among newly diagnosed TB cases?=?15 years of age. Delay was analyzed at three levels: the periods between 1) onset of TB symptoms and first visit to medical provider, i.e. patients’ delay, 2) the first visit to a medical provider and the initiation of treatment i.e. health systems’ delay and 3) onset of TB symptoms and initiation of treatment i.e. total delay. Uni- and multi-variate logistic regression analyses were performed to investigate predictors of patients’, health systems’ and total delays. Results The median time of patients’ delay was 21 days [(interquartile range (IQR) (7 days, 60 days)]. The median health systems’ delay was 27 days (IQR 8 days, 60 days) and the median total delay was 60 days (IQR 30 days, 121 days). Patients residing in rural areas had a three-fold increase in patients’ delay compared to those from urban areas [Adjusted Odds Ratio (AOR) 3.4; 95% (CI 1.3, 8.9)]. Extra-pulmonary TB (EPTB) cases were more likely to experience delay in seeking treatment compared to pulmonary (PTB) cases [(AOR 2.6; 95% (CI 1.3, 5.4)]. Study subjects who first visited health centres [(AOR) 5.1; 95% (CI 2.1, 12.5)], private facilities [(AOR) 3.5; 95% (CI 1.3, 9.7] and health posts [(AOR) 109; 95% (CI 12, 958], were more likely to experience an increase in health systems’ delay compared to those who visited hospitals. Conclusions The majority of TB patients reported to medical providers within an acceptable time after the onset of symptoms. Rural residence was associated with patients’ and total delays. Providing the population with information about TB symptoms and the importance of early health seeking may be an efficient way to decrease TB transmission, morbidity and mortality. Establishing efficient TB diagnostic and treatment facilities at the periphery level is imperative to reduce diagnostic delay and expedite TB treatment

Vorticity, divergence, and vertical velocity in a baroclinic boundary layer with a linear variation of the geostrophic wind

The Ekman-Taylor problem for the planetary boundary layer is solved in the case of a thermal wind which varies linearly with height. The upper boundary condition is a vanishing ageostrophic wind, while the lower boundary condition is continuity of the stress vector across the interface between the planetary boundary layer and the surface layer. The latter condition is used to determine the magnitude and the direction of the wind at the bottom of the Ekman layer.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/42509/1/10546_2005_Article_BF02137679.pd

Eddy genesis and manipulation in plane laminar shear flow

Eddy formation and presence in a plane laminar shear flow configuration consisting of two infinitely long plates orientated parallel to each other is investigated theoretically. The upper plate, which is planar, drives the flow; the lower one has a sinusoidal profile and is fixed. The governing equations are solved via a full finite element formulation for the general case and semi-analytically at the Stokes flow limit. The effects of varying geometry (involving changes in the mean plate separation or the amplitude and wavelength of the lower plate) and inertia are explored separately. For Stokes flow and varying geometry, excellent agreement between the two methods of solution is found. Of particular interest with regard to the flow structure is the importance of the clearance that exists between the upper plate and the tops of the corrugations forming the lower one. When the clearance is large, an eddy is only present at sufficiently large amplitudes or small wavelengths. However, as the plate clearance is reduced, a critical value is found which triggers the formation of an eddy in an otherwise fully attached flow for any finite amplitude and arbitrarily large wavelength. This is a precursor to the primary eddy to be expected in the lid-driven cavity flow which is formed in the limit of zero clearance between the plates. The influence of the flow driving mechanism is assessed by comparison with corresponding solutions for the case of gravity-driven fluid films flowing over an undulating substrate. When inertia is present, the flow generally becomes asymmetrical. However, it is found that for large mean plate separations the flow local to the lower plate becomes effectively decoupled from the inertia dominated overlying flow if the wavelength of the lower plate is sufficiently small. In such cases the local flow retains its symmetry. A local Reynolds number based on the wavelength is shown to be useful in characterising these large-gap flows. As the mean plate separation is reduced, the form of the asymmetry caused by inertia changes, and becomes strongly dependent on the plate separation. For lower plate wavelengths which do not exhibit a cinematically induced secondary eddy, an inertially induced secondary eddy can be created if the mean plate separation is sufficiently small and the global Reynolds number sufficiently large

Comments on: "Starting solutions for some unsteady unidirectional flows of a second grade fluid," [Int. J. Eng. Sci. 43 (2005) 781]

A significant mathematical error is identified and corrected in a recent highly-cited paper on oscillatory flows of second-grade fluids [Fetecau & Fetecau (2005). Int. J. Eng. Sci., 43, 781--789]. The corrected solutions are shown to agree identically with numerical ones generated by a finite-difference scheme, while the original ones of Fetecau & Fetecau do not. A list of other recent papers in the literature that commit the error corrected in this Comment is compiled. Finally, a summary of related erroneous papers in this journal is presented as an Appendix.Comment: 8 pages, 2 figures (4 images), elsarticle class; accepted for publication in International Journal of Engineering Scienc

Three-body recombination rates near a Feshbach resonance within a two-channel contact interaction model

We calculate the three-body recombination rate into a shallow dimer in a gas of cold bosonic atoms near a Feshbach resonance using a two-channel contact interaction model. The two-channel model naturally describes the variation of the scattering length through the Feshbach resonance and has a finite effective range. We confront the theory with the available experimental data and show that the two-channel model is able to quantitatively describe the existing data. The finite effective range leads to a reduction of the scaling factor between the recombination minima from the universal value of 22.7. The reduction is larger for larger effective ranges or, correspondingly, for narrower Feshbach resonances.Comment: 9 pages, 7 figure

Biologiske ressurser i området som er aktuelt som trasé for kraftkabler fra Norge til kontinentet

Rapporten er utarbeidet på oppdrag fra Statkraft Engineering, i anledning planleggingen av linjenett for overføring av elektrisk kraft fra Norge til kontinentet. Utredningen er en del av arbeidet med å vurdere konsekvensene for marine biologiske ressurser ved overføring av elektrisk kraft i monopol likestrømskabel. Rapporten er en sammenstillelse av kunnskap om biologiske ressurser i området som er aktuellt for elektrodeanlegg og kabel. Det er gitt en beskrivelse samt kartmessig framstilling av utbredelse av viktige fiskebestander i området, samt migasjon av fisk gjennom det aktuelle området

Mobile phone based mini-spectrometer for rapid screening of skin cancer

We demonstrate a highly sensitive mobile phone based spectrometer that has potential to detect cancerous skin lesions in a rapid, non-invasive manner. Earlier reports of low cost spectrometers utilize the camera of the mobile phone to image the field after moving through a diffraction grating. These approaches are inherently limited by the closed nature of mobile phone image sensors and built in optical elements. The system presented uses a novel integrated grating and sensor that is compact, accurate and calibrated. Resolutions of about 10 nm can be achieved. Additionally, UV and visible LED excitation sources are built into the device. Data collection and analysis is simplified using the wireless interfaces and logical control on the smart phone. Furthermore, by utilizing an external sensor, the mobile phone camera can be used in conjunction with spectral measurements. We are exploring ways to use this device to measure endogenous fluorescence of skin in order to distinguish cancerous from non-cancerous lesions with a mobile phone based dermatoscope

Phononic drumhead surface state in the distorted kagome compound RhPb

RhPb was initially recognized as one of CoSn-like compounds with P6/mmm symmetry, containing an ideal kagome lattice of d-block atoms. However, theoretical calculations predict the realization of the phonon soft mode, which leads to the kagome lattice distortion and stabilization of the structure with P$\bar{6}$2m symmetry [A. Ptok et al., Phys. Rev. B 104, 054305 (2021)]. Here, we present the single crystal x-ray diffraction results supporting this prediction. Furthermore, we discuss the main dynamical properties of RhPb with P$\bar{6}$2m symmetry, i.e. phonon dispersions and surface Green's functions using the modern theoretical methods based on density functional theory. The bulk phononic dispersion curves contain several flattened bands, Dirac nodal lines, and triple degenerate Dirac points. As a consequence, the phononic drumhead surface state is realized for the (100) surface, terminated by the zigzaglike edge of Pb honeycomb sublattice