303 research outputs found
Numerical simulation of secondary breakup of shear-thinning droplets
The breakup of non-Newtonian droplets is ubiquitous in numerous applications.
Although the non-Newtonian property can significantly change the droplet
breakup process, most previous studies consider Newtonian droplets, and the
effects of the non-Newtonian properties on the breakup process are still
unclear. This study focuses on the secondary breakup of shear-thinning droplets
by numerical simulation. The volume of fluid method is used to capture
interface dynamics on adaptive grids. To compare shear-thinning droplets and
Newtonian droplets, a new definition of the Ohnesorge number is proposed by
considering the characteristic shear rate in the droplet induced by the
airflow. The results show that compared with the Newtonian fluid, the
shear-thinning properties can change the effective viscosity distribution
inside the droplet, alter the local deformation, change the droplet morphology,
and affect the transition in the droplet breakup regime.Comment: 14 pages, 15 figure
FedDCT: A Dynamic Cross-Tier Federated Learning Scheme in Wireless Communication Networks
With the rapid proliferation of Internet of Things (IoT) devices and the
growing concern for data privacy among the public, Federated Learning (FL) has
gained significant attention as a privacy-preserving machine learning paradigm.
FL enables the training of a global model among clients without exposing local
data. However, when a federated learning system runs on wireless communication
networks, limited wireless resources, heterogeneity of clients, and network
transmission failures affect its performance and accuracy. In this study, we
propose a novel dynamic cross-tier FL scheme, named FedDCT to increase training
accuracy and performance in wireless communication networks. We utilize a
tiering algorithm that dynamically divides clients into different tiers
according to specific indicators and assigns specific timeout thresholds to
each tier to reduce the training time required. To improve the accuracy of the
model without increasing the training time, we introduce a cross-tier client
selection algorithm that can effectively select the tiers and participants.
Simulation experiments show that our scheme can make the model converge faster
and achieve a higher accuracy in wireless communication networks
Cell separation using tilted-angle standing surface acoustic waves
Separation of cells is a critical process for studying cell properties, disease diagnostics, and therapeutics. Cell sorting by acoustic waves offers a means to separate cells on the basis of their size and physical properties in a label-free, contactless, and biocompatible manner. The separation sensitivity and efficiency of currently available acoustic-based approaches, however, are limited, thereby restricting their widespread application in research and health diagnostics. In this work, we introduce a unique configuration of tilted-angle standing surface acoustic waves (taSSAW), which are oriented at an optimally designed inclination to the flow direction in the microfluidic channel. We demonstrate that this design significantly improves the efficiency and sensitivity of acoustic separation techniques. To optimize our device design, we carried out systematic simulations of cell trajectories, matching closely with experimental results. Using numerically optimized design of taSSAW, we successfully separated 2- and 10-Āµm-diameter polystyrene beads with a separation efficiency of ~99%, and separated 7.3- and 9.9-Āµm-polystyrene beads with an efficiency of ~97%. We illustrate that taSSAW is capable of effectively separating particlesācells of approximately the same size and density but different compressibility. Finally, we demonstrate the effectiveness of the present technique for biologicalābiomedical applications by sorting MCF-7 human breast cancer cells from nonmalignant leukocytes, while preserving the integrity of the separated cells. The method introduced here thus offers a unique route for separating circulating tumor cells, and for label-free cell separation with potential applications in biological research, disease diagnostics, and clinical practice.National Institutes of Health (U.S.) (Grant U01HL114476)National Institutes of Health (U.S.) (New Innovator Award 1DP2OD007209-01)National Science Foundation (U.S.). Materials Research Science and Engineering Centers (Program) (Grant DMR-0820404
Engineering Properties of Sweet Potato Starch for Industrial Applications by Biotechnological Techniques Including Genome Editing
Sweet potato (Ipomoea batatas) is one of the largest food crops in the world. Due to its abundance of starch, sweet potato is a valuable ingredient in food derivatives, dietary supplements, and industrial raw materials. In addition, due to its ability to adapt to a wide range of harsh climate and soil conditions, sweet potato is a crop that copes well with the environmental stresses caused by climate change. However, due to the complexity of the sweet potato genome and the long breeding cycle, our ability to modify sweet potato starch is limited. In this review, we cover the recent development in sweet potato breeding, understanding of starch properties, and the progress in sweet potato genomics. We describe the applicational values of sweet potato starch in food, industrial products, and biofuel, in addition to the effects of starch properties in different industrial applications. We also explore the possibility of manipulating starch properties through biotechnological means, such as the CRISPR/Cas-based genome editing. The ability to target the genome with precision provides new opportunities for reducing breeding time, increasing yield, and optimizing the starch properties of sweet potatoes
Neurologic Abnormalities in Workers of a 1-Bromopropane Factory
We reported recently that 1-bromopropane (1-BP; n-propylbromide, CAS Registry no. 106-94-5), an alternative to ozone-depleting solvents, is neurotoxic and exhibits reproductive toxicity in rats. The four most recent case reports suggested possible neurotoxicity of 1-BP in workers. The aim of the present study was to establish the neurologic effects of 1-BP in workers and examine the relationship with exposure levels. We surveyed 27 female workers in a 1-BP production factory and compared 23 of them with 23 age-matched workers in a beer factory as controls. The workers were interviewed and examined by neurologic, electrophysiologic, hematologic, biochemical, neurobehavioral, and postural sway tests. 1-BP exposure levels were estimated with passive samplers. Tests with a tuning fork showed diminished vibration sensation of the foot in 15 workers exposed to 1-BP but in none of the controls. 1-BP factory workers showed significantly longer distal latency in the tibial nerve than did the controls but no significant changes in motor nerve conduction velocity. Workers also displayed lower values in sensory nerve conduction velocity in the sural nerve, backward recalled digits, Benton visual memory test scores, pursuit aiming test scores, and five items of the Profile of Mood States (POMS) test (tension, depression, anxiety, fatigue, and confusion) compared with controls matched for age and education. Workers hired after May 1999, who were exposed to 1-BP only (workers hired before 1999 could have also been exposed to 2-BP), showed similar changes in vibration sense, distal latency, Benton test scores, and depression and fatigue in the POMS test. Time-weighted average exposure levels in the workers were 0.34ā49.19 ppm. Exposure to 1-BP could adversely affect peripheral nerves or/and the central nervous system
A Linear Approximate Algorithm for Earth Mover's Distance with Thresholded Ground Distance
Effective and efficient image comparison plays a vital role in content-based image retrieval (CBIR). The earth moverās distance (EMD) is an enticing measure for image comparison, offering intuitive geometric interpretation and modelling the human perceptions of similarity. Unfortunately, computing EMD, using the simplex method, has cubic complexity. FastEMD, based on min-cost flow, reduces the complexity to (O(N2logā”N)). Although both methods can obtain the optimal result, the high complexity prevents the application of EMD on large-scale image datasets. Thresholding the ground distance can make EMD faster and more robust, since it can decrease the impact of noise and reduce the range of transportation. In this paper, we present a new image distance metric, EMD+, which applies a threshold to the ground distance. To compute EMD+, the FastEMD approach can be employed. We also propose a novel linear approximation algorithm. Our algorithm achieves ON complexity with the benefit of qualified bins. Experimental results show that (1) our method is 2 to 3 orders of magnitude faster than EMD (computed by FastEMD) and 2 orders of magnitude faster than FastEMD and (2) the precision of our approximation algorithm is no less than the precision of FastEMD
Above-knee Prosthesis Control Based on Posture Recognition by Support Vector Machine
Abstract-In order for individuals suffering from transfemoral amputation to walk in a variety of circumstances, the above-knee prosthesis based on posture recognition was presented. The body posture of lower limb was classified into four classes, "stair", "sitting", "standing", and "walking". For measure the amputee's movement intent, surface EMG signals which can reflect amputee's movement intent and can be measured without invasion were applied to identify postural adjustments by support vector machine. The result of this study indicates that this method can recognize every postural adjustment with a higher identification rate, and has a great potential in practical application of artificial lower limb
Altered Functional Connectivity in an Aged Rat Model of Postoperative Cognitive Dysfunction: A Study Using Resting-State Functional MRI
BACKGROUND: Postoperative cognitive impairment is a common complication after cardiac and major non-cardiac surgery in the elderly, but its causes and mechanisms remain unclear. The purpose of the current study was to use resting-state functional magnetic resonance imaging (fMRI) to explore changes in the functional connectivity, i.e. the synchronization of low frequency fluctuation (LFF), in an animal model of cognitive impairment in aged rats. METHODS: Aged (22 months) rats were anaesthetized with 40 Āµg/kg fentanyl and 500 Āµg/kg droperidol (intraperitoneal) for splenectomy. Cognitive function was assessed using Y maze prior to operation and on postoperative days 1, 3 and 9. To evaluate functional connectivity, resting-state fMRI data were acquired using a 3T MR imaging system with a 4 channel phase array rat head coil. RESULTS: Cognitive function was impaired at postoperative days 1 and 3 compared with preoperative. Significant synchronized LFF was detected bilaterally in the primary somatosensory cortex and hippocampus preoperatively. By contrast, no significant LFF synchronization was detected in the right primary somatosensory cortex and right hippocampus on postoperative days 1 and 3, although the pattern of functional connectivity had become almost normal by day 9. CONCLUSION: Splenectomy performed under neuroleptic anaesthesia triggers a cognitive decline that is associated with altered spontaneous neuronal activity in the cortex and hippocampus
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