Crater formation during raindrop impact on sand

After a raindrop impacts on a granular bed, a crater is formed as both drop and target deform. After an initial, transient, phase in which the maximum crater depth is reached, the crater broadens outwards until a final steady shape is attained. By varying the impact velocity of the drop and the packing density of the bed, we find that avalanches of grains are important in the second phase and hence, affect the final crater shape. In a previous paper, we introduced an estimate of the impact energy going solely into sand deformation and here we show that both the transient and final crater diameter collapse with this quantity for various packing densities. The aspect ratio of the transient crater is however altered by changes in the packing fraction.Comment: 9 pages, 9 figure

Liquid-grain mixing suppresses droplet spreading and splashing during impact

Would a raindrop impacting on a coarse beach behave differently from that impacting on a desert of fine sand? We study this question by a series of model experiments, where the packing density of the granular target, the wettability of individual grains, the grain size, the impacting liquid, and the impact speed are varied. We find that by increasing the grain size and/or the wettability of individual grains the maximum droplet spreading undergoes a transition from a capillary regime towards a viscous regime, and splashing is suppressed. The liquid-grain mixing is discovered to be the underlying mechanism. An effective viscosity is defined accordingly to quantitatively explain the observations

REFORM: Removing False Correlation in Multi-level Interaction for CTR Prediction

Click-through rate (CTR) prediction is a critical task in online advertising and recommendation systems, as accurate predictions are essential for user targeting and personalized recommendations. Most recent cutting-edge methods primarily focus on investigating complex implicit and explicit feature interactions. However, these methods neglect the issue of false correlations caused by confounding factors or selection bias. This problem is further magnified by the complexity and redundancy of these interactions. We propose a CTR prediction framework that removes false correlation in multi-level feature interaction, termed REFORM. The proposed REFORM framework exploits a wide range of multi-level high-order feature representations via a two-stream stacked recurrent structure while eliminating false correlations. The framework has two key components: I. The multi-level stacked recurrent (MSR) structure enables the model to efficiently capture diverse nonlinear interactions from feature spaces of different levels, and the richer representations lead to enhanced CTR prediction accuracy. II. The false correlation elimination (FCE) module further leverages Laplacian kernel mapping and sample reweighting methods to eliminate false correlations concealed within the multi-level features, allowing the model to focus on the true causal effects. Extensive experiments based on four challenging CTR datasets and our production dataset demonstrate that the proposed REFORM model achieves state-of-the-art performance. Codes, models and our dataset will be released at https://github.com/yansuoyuli/REFORM.Comment: 9 pages, 5 figure

Photothermal inactivation of heat-resistant bacteria on nanoporous gold disk arrays

A rapid photothermal bacterial inactivation technique has been developed by irradiating near-infrared (NIR) light onto bacterial cells (Escherichia coli, Bacillus subtilis, Exiguobacterium sp. AT1B) deposited on surfaces coated with a dense, random array of nanoporous gold disks (NPGDs). With the use of cell viability tests and SEM imaging results, the complete inactivation of the pathogenic and heat-resistant bacterial model strains is confirmed within ~25 s of irradiation of the NPGD substrate. In addition to irradiation control experiments to prove the efficacy of the bacterial inactivation, thermographic imaging showed an immediate averaged temperature rise above 200 °C within the irradiation spot of the NPGD substrate. The light-gated photothermal effects on the NPGD substrate offers potential applications for antimicrobial and nanotherapeutic devices due to strong light absorption in the tissue optical window, i.e., the NIR wavelengths, and robust morphological structure that can withstand high instantaneous thermal shocks

Seroprevalence of Toxoplasma gondii infection in dairy goats in Shaanxi Province, Northwestern China

<p>Abstract</p> <p>Background</p> <p><it>Toxoplasma gondii </it>is an important zoonotic pathogen causing significant human and animal health problems. Infection in dairy goats not only results in significant reproductive losses, but also represents an important source of human infection due to consumption of infected meat and milk. In the present study we report for the first time seroprevalence of <it>T. gondii </it>infection in Guanzhong and Saanen dairy goats in Shaanxi province, Northwestern China.</p> <p>Results</p> <p>Sera from 751 dairy goats from 9 farms in 6 counties were examined for <it>T. gondii </it>antibodies with an indirect haemagglutination (IHA) test. Antibodies to <it>T. gondii </it>were detected in 106 (14.1%) serum samples, with antibody titres ranging from 1:64 to 1:1024. Seropositive goats were found in all 9 farms and seroprevalences in Guanzhong (16.3%, 75/461) and Saanen (10.7%, 31/290) dairy goats were not statistically significantly different. All the factors (sex, age and location) reported in the present study affected prevalence of infection, and seroprevalence increased with age, suggesting postnatal acquisition of <it>T. gondii </it>infection.</p> <p>Conclusions</p> <p>The results of the present survey indicate that infection by <it>T. gondii </it>is widely prevalent in dairy goats in Shaanxi province, Northwestern China, and this has implications for prevention and control of toxoplasmosis in this province.</p

Multi-ancestry study of blood lipid levels identifies four loci interacting with physical activity.

Many genetic loci affect circulating lipid levels, but it remains unknown whether lifestyle factors, such as physical activity, modify these genetic effects. To identify lipid loci interacting with physical activity, we performed genome-wide analyses of circulating HDL cholesterol, LDL cholesterol, and triglyceride levels in up to 120,979 individuals of European, African, Asian, Hispanic, and Brazilian ancestry, with follow-up of suggestive associations in an additional 131,012 individuals. We find four loci, in/near CLASP1, LHX1, SNTA1, and CNTNAP2, that are associated with circulating lipid levels through interaction with physical activity; higher levels of physical activity enhance the HDL cholesterol-increasing effects of the CLASP1, LHX1, and SNTA1 loci and attenuate the LDL cholesterol-increasing effect of the CNTNAP2 locus. The CLASP1, LHX1, and SNTA1 regions harbor genes linked to muscle function and lipid metabolism. Our results elucidate the role of physical activity interactions in the genetic contribution to blood lipid levels