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Impact of microspheres on liquid surfaces is a universal phenomenon in nature and in industrial processes. However, most relevant studies have mainly focused on the sphere's vertical impact. Herein, we present the first observation on the oblique impact of microspheres on the surface of quiescent liquid using high-speed microphotography. The sphere motion and liquid surface distortion after the oblique impact are basically different from those after a vertical impact. The sphere rotates and its trajectory deviates from the impact direction during the oblique impact process, while the non-axisymmetric liquid surface distortion experiences an evolution from half-cavity to full-cavity patterns. The dependence of motions of the sphere and the three-phase contact line on the impact angle
and Weber number are investigated, and the scaling laws for the sphere's penetration time and penetration depth are given. We provide a phase diagram with respect to the Weber number and impact angle that describes the observed impact modes of submergence and oscillation, which shows that the critical Weber number between two impact modes increases when the impact angle decreases. Additionally, a scaling model is established based on energy balance to distinguish different impact modes. The model indicates that the critical Weber number for the microsphere's oblique impact is equal to
times that for vertical impact, agreeing well with the experimental results.
Facilitated by the establishment of terrestrial networks and satellite constellations of Automatic Identification System (AIS) receivers, large quantities of spatial and temporal information that trace ships' paths have been collected. The exponential increase in the amount of AIS data has caused expensive and time-consuming transmission, calculation and storage problems. Using appropriate trajectory simplification methods in a timely manner to compress redundant information while minimising the loss of importation information is important. To minimise the simplification error, this paper proposes an online multi-dimensional simplification algorithm for AIS trajectory streaming data. The simplification algorithm takes into account position, direction and speed preservation. Finally, a comparison experiment with other algorithms is made to examine the effectiveness of this algorithm. The results indicate that the proposed online multi-dimensional simplification algorithm can effectively preserve a ship's motion state, including its position, speed and course.
This paper is devoted to the American option pricing problem governed by the Black-Scholes equation. The existence of an optimal exercise policy makes the problem a free boundary value problem of a parabolic equation on an unbounded domain. The optimal exercise boundary satisfies a nonlinear Volterra integral equation and is solved by a high-order collocation method based on graded meshes. This free boundary is then deformed to a fixed boundary by the front-fixing transformation. The boundary condition at infinity (due to the fact that the underlying asset's price could be arbitrarily large in theory), is treated by the perfectly matched layer technique. Finally, the resulting initial-boundary value problems for the option price and some of the Greeks on a bounded rectangular space-time domain are solved by a finite element method. In particular, for Delta, one of the Greeks, we propose a discontinuous Galerkin method to treat the discontinuity in its initial condition. Convergence results for these two methods are analyzed and several numerical simulations are provided to verify these theoretical results.
The pricing model for American lookback options can be characterised as a two-dimensional free boundary problem. The main challenge in this problem is the free boundary, which is also the main concern for financial investors. We use a standard technique to reduce the pricing model to a one-dimensional linear complementarity problem on a bounded domain and obtain a corresponding variational inequality. The inequality is discretised by finite differences and finite elements in the temporal and spatial directions, respectively. By enforcing inequality constraints related to the options using Lagrange multipliers, the discretised variational inequality is reformulated as a set of semi-smooth equations, which are solved by a primal-dual active set method. One of the major advantages of our algorithm is that we can obtain the option values and the free boundary simultaneously, and numerical simulations show that our approach is as efficient as some other methods.
We report a novel approach to the instantaneous photoinitiated synthesis of mixed anatase-rutile nanocrystalline TiO2 thin films with a three-dimensional nanostructure through pulsed white light irradiation of photosensitive Ti-organic precursor films. Pulsed photoinitiated pyrolysis accompanied by instantaneous self-assembly and crystallization occurred to form graphitic oxides-coated TiO2 nanograins. Subsequent pulsed light irradiation working as in situ pulsed photothermal treatment improved the crystalline quality of TiO2 film despite its low attenuation of light. The non-radiative recombination of photogenerated electrons and holes in TiO2 nanograins, coupled with inefficient heat dissipation due to low thermal conductivity, produces enough heat to provide the thermodynamic driving force for improving the crystalline quality. The graphitic oxides were reduced by pulsed photothermal treatment and can be completely removed by oxygen plasma cleaning. This photoinitiated nanofabrication technology opens a promising way for the low-cost and high-throughput manufacturing of nanostructured metal oxides as well as TiO2 nanocrystalline thin films.
Objective: To study the relationship of Nε-(carboxymethyl)-lysine level (CML)
with microstructure changes of white matter (WM), and cognitive impairment
in patients with type 2 diabetes mellitus (T2DM) and to discuss the
potential mechanism underlying T2DM-associated cognitive impairment. Methods: The study was performed in T2DM patients (n=22) with disease course
≥5 years and age ranging from 65 to 75 years old. A control group consisted
of 25 sex- and age-matched healthy volunteers. Fractional anisotropy (FA) of
several WM regions was analyzed by diffusion tensor imaging scan. Plasma CML
levels were measured by enzyme-linked immunosorbent assay, and cognitive
function was assessed by Mini-Mental State Examination and Montreal
cognitive assessment (MoCA). Results: The total Mini-Mental State Examination score in the patient group
(25.72±3.13) was significantly lower than the control group (28.16±2.45)
(p<0.05). In addition, the total MoCA score in the patient group
(22.15±3.56) was significantly lower than the control group 25.63±4.12)
(p<0.01). In the patient group, FA values were significantly decreased in
the corpus callosum, cingulate fasciculus, inferior fronto-occipital
fasciculus, parietal WM, hippocampus, and temporal lobes relative to
corresponding regions of healthy controls (p<0.05). Plasma CML level was
negatively correlated with average FA values in the global brain (r=−0.58,
p<0.01) and MoCA scores (r=−0.47, p<0.05). Conclusions: In T2DM, WM microstructure changes occur in older patients, and
elevations in CML may play a role in the development of cognitive
According to most prospective studies, being underweight (BMI<18·5 kg/m2) is associated with significantly higher mortality than being of normal weight, especially among smokers. We aimed to explore in a generally lean population whether being underweight is significantly associated with increased all-cause mortality.
Prospective cohort study.
Korea Medical Insurance Corporation study with 14 years of follow-up.
After excluding deaths within the first 5 years of follow-up (1993–1997) to minimize reverse causation and excluding participants without information about smoking and health status, 94 133 men and 48 496 women aged 35–59 years in 1990 were included.
We documented 5411 (5·7 %) deaths in men and 762 (1·6 %) in women. Among never smokers, hazard ratios (HR) for underweight individuals were not significantly higher than those for normal-weight individuals (BMI=18·5–22·9 kg/m2): HR=0·87 (95 % CI 0·41, 1·84, P=0·72) for underweight men and HR=1·12 (95 % CI 0·76, 1·65, P=0·58) for underweight women. Among ex-smokers, HR=0·86 (95 % CI 0·38, 1·93, P=0·72) for underweight men and HR=3·77 (95 % CI 0·42, 32·29, P=0·24) for underweight women. Among current smokers, HR=1·60 (95 % CI 1·28, 2·01, P<0·001) for underweight men and HR=2·07 (95 % CI 0·43, 9·94, P=0·36) for underweight women.
The present study does not support that being underweight per se is associated with increased all-cause mortality in Korean men and women.
This paper presents a vision-based obstacle avoidance design using a monocular camera onboard a mobile robot. A novel image processing procedure is developed to estimate the distance between the robot and obstacles based-on inverse perspective transformation (IPT) in an image plane. A robust image processing solution is proposed to detect and segment a drivable ground area within the camera view. The proposed method integrates robust feature matching with adaptive color segmentation for plane estimation and tracking to cope with variations in illumination and camera view. After IPT and ground region segmentation, distance measurement results are obtained similar to those of a laser range finder for mobile robot obstacle avoidance and navigation. The merit of this algorithm is that the mobile robot can have the capacity of path finding and obstacle avoidance by using a single monocular camera. Practical experimental results on a wheeled mobile robot show that the proposed imaging system successfully obtains distances of surrounding objects for reactive navigation in an indoor environment.
Synthesis of titania (TiO2) nanorods on various substrates has recently attracted attention for energy and environmental applications. Herein, we report growth of nanostructured TiO2 on Si(111) and glass borosilicate substrates by a two-step method. A thin film of anatase TiO2 was first laid down by spin coating and annealing, followed by the growth of rutile TiO2 nanorods with a hydrothermal method. To understand the role of the polycrystalline anatase TiO2 seed layer, we selected a relatively high temperature for the hydrothermal reaction, e.g., 175 °C at which no rutile TiO2 nanorods could grow without the precoated anatase TiO2 layer. The morphology and microstructure of both the polycrystalline anatase and rutile nanorod layers were characterized by electron microscopy and x-ray powder diffraction. Such a two-step fabrication method makes it possible to grow TiO2 nanorods on almost any substrate.
We consider Chinese cultural, psychological and social factors that are likely to place boundaries on the applicability of DeNisi and Pritchard's motivational framework and discuss how these cultural barriers play out at each of the links in their model. We conclude with a summary and a discussion of some of the broader implications of applying models of work motivation to a Chinese economy in transition.
While investigating the reversible seasonal obesity of Siberian hamsters, direct sympathetic nervous system (SNS) postganglionic innervation of white adipose tissue (WAT) has been demonstrated using anterograde and retrograde tract tracers. The primary function of this innervation is lipid mobilization. The brain SNS outflow to WAT has been defined using the pseudorabies virus (PRV), a retrograde transneuronal tract tracer. These PRV-labelled SNS outflow neurons are extensively co-localized with melanocortin-4 receptor mRNA, which, combined with functional data, suggests their involvement in lipolysis. The SNS innervation of WAT also regulates fat cell number, as noradrenaline inhibits and WAT denervation stimulates fat cell proliferation in vitro and in vivo respectively. The sensory innervation of WAT has been demonstrated by retrograde tract tracing, electrophysiological recording and labelling of the sensory-associated neuropeptide calcitonin gene-related peptide in WAT. Local injections of the sensory nerve neurotoxin capsaicin into WAT selectively destroy this innervation. Just as surgical removal of WAT pads triggers compensatory increases in lipid accretion by non-excised WAT depots, capsaicin-induced sensory denervation triggers increases in lipid accretion of non-capsaicin-injected WAT depots, suggesting that these nerves convey information about body fat levels to the brain. Finally, parasympathetic nervous system innervation of WAT has been suggested, but the recent finding of no WAT immunoreactivity for the possible parasympathetic marker vesicular acetylcholine transporter (VAChT) argues against this claim. Collectively, these data suggest several roles for efferent and afferent neural innervation of WAT in body fat regulation.
The Raman-active modes of solid films of MxC60 (x-0, 6; M=K, Rb, Cs) and K3C60 have been studied experimentally. The mode-activity is dominated by intraball interactions, and the effect of the M + ions on the C60 spectrum is observed to be almost insensitive to the radius or mass of the alkali metal. Tangential modes of solid C60 are observed to soften in M660 by -60 cm−1, which can be attributed to a charge-transfer-induced elongation of the intraball bond lengths, similar to that observed in graphite intercalation compounds. Conversely, the radial modes are found to upshift slightly, indicating that a competing mechanism counteracts the effect of the bond elongation. For K3C60, six Raman lines have been observed in which the lowest frequency mode exhibits a Breit-Wigner-Fano lineshape, indicating a coupling between the lowest frequency Hq-derived intramolecular modes of C60 and a broad Raman-active continuum with the same symmetry lying lower in frequency.
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