Pattern Dynamics of Vortex Ripples in Sand: Nonlinear Modeling and Experimental Validation

Vortex ripples in sand are studied experimentally in a one-dimensional setup with periodic boundary conditions. The nonlinear evolution, far from the onset of instability, is analyzed in the framework of a simple model developed for homogeneous patterns. The interaction function describing the mass transport between neighboring ripples is extracted from experimental runs using a recently proposed method for data analysis, and the predictions of the model are compared to the experiment. An analytic explanation of the wavelength selection mechanism in the model is provided, and the width of the stable band of ripples is measured.Comment: 4 page

The influence of change in feeding and management on the prevalence of multi-resistant Salmonella typhimurium DTI 04 in Danish pigherds. Four case stories

In the period June-December 1998 attempt were made to reduce the apparent prevalence of multi-resistant Salmonella Typhimurium DTI04 in four infected herds. The interventions were intensive rodent control, thorough cleaning, inclusion of organic acid in feed/water, and feeding non heat treated feed (to mimic home mixed feed). Every month 50-70 pooled faecal samples were collected from each herd. The four herds showed great variation in apparent prevalence between age groups in the same herd

Haemodynamics and flow modification stents for peripheral arterial disease:a review

Endovascular stents are widely used for the treatment of peripheral arterial disease (PAD). However, the development of in-stent restenosis and downstream PAD progression remain a challenge. Stent revascularisation of PAD causes arterial trauma and introduces abnormal haemodynamics, which initiate complicated biological processes detrimental to the arterial wall. The interaction between stent struts and arterial cells in contact, and the blood flow field created in a stented region, are highly affected by stent design. Spiral flow is known as a normal physiologic characteristic of arterial circulation and is believed to prevent the development of flow disturbances. This secondary flow motion is lost in atheromatous disease and its re-introduction after endovascular treatment of PAD has been suggested as a method to induce stabilised and coherent haemodynamics. Stent designs able to generate spiral flow may support endothelial function and therefore increase patency rates. This review is focused on secondary flow phenomena in arteries and the development of flow modification stent technologies for the treatment of PAD

The influence of change in feeding and management on the prevalence of multi-resistant Salmonella typhimurium DTI 04 in Danish pigherds. Four case stories

In the period June-December 1998 attempt were made to reduce the apparent prevalence of multi-resistant Salmonella Typhimurium DTI04 in four infected herds. The interventions were intensive rodent control, thorough cleaning, inclusion of organic acid in feed/water, and feeding non heat treated feed (to mimic home mixed feed). Every month 50-70 pooled faecal samples were collected from each herd. The four herds showed great variation in apparent prevalence between age groups in the same herd.</p

Superhuman Hearing - Virtual Prototyping of Artificial Hearing: A Case Study on Interactions and Acoustic Beamforming

Directivity and gain in microphone array systems for hearing aids or hearable devices allow users to acoustically enhance the information of a source of interest. This source is usually positioned directly in front. This feature is called acoustic beamforming. The current study aimed to improve users' interactions with beamforming via a virtual prototyping approach in immersive virtual environments (VEs). Eighteen participants took part in experimental sessions composed of a calibration procedure and a selective auditory attention voice-pairing task. Eight concurrent speakers were placed in an anechoic environment in two virtual reality (VR) scenarios. The scenarios were a purely virtual scenario and a realistic 360° audio-visual recording. Participants were asked to find an individual optimal parameterization for three different virtual beamformers: (i) head-guided, (ii) eye gaze-guided, and (iii) a novel interaction technique called dual beamformer, where head-guided is combined with an additional hand-guided beamformer. None of the participants were able to complete the task without a virtual beamformer (i.e., in normal hearing condition) due to the high complexity introduced by the experimental design. However, participants were able to correctly pair all speakers using all three proposed interaction metaphors. Providing superhuman hearing abilities in the form of a dual acoustic beamformer guided by head and hand movements resulted in statistically significant improvements in terms of pairing time, suggesting the task-relevance of interacting with multiple points of interests