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An Enhanced Tilted-Angle Acoustofluidic Chip for Cancer Cell Manipulation
No full textIn recent years, surface acoustic wave (SAW) devices have demonstrated great potentials and increasing applications in the manipulation of nano- and micro-particles including biological cells with the advantages of label-free, high sensitivity and accuracy. In this letter, we introduce a novel tilted-angle SAW devices to optimise the acoustic pressure inside a microchannel for cancer-cell manipulation. The SAW generation and acoustic radiation force are improved by seamlessly patterning electrodes in the space surrounding the microchannel. Comparisons between this novel SAW device and a conventional device show a 32% enhanced separation efficiency while the input power, manufacturing cost and fabrication effort remain the same. Effective separation of HeLa cancer cells from peripheral blood mononuclear cells is demonstrated. This novel SAW device has the advantages in minimizing device power consumption, lowering component footprint and increasing device density
How is flexible electronics advancing neuroscience research?
No full textInnovative neurotechnology must be leveraged to experimentally answer the multitude of pressing questions in modern neuroscience. Driven by the desire to address the existing neuroscience problems with newly engineered tools, we discuss in this review the benefits of flexible electronics for neuroscience studies. We first introduce the concept and define the properties of flexible and stretchable electronics. We then categorize the four dimensions where flexible electronics meets the demands of modern neuroscience: chronic stability, interfacing multiple structures, multi-modal compatibility, and neuron-type-specific recording. Specifically, with the bending stiffness now approaching that of neural tissue, implanted flexible electronic devices produce little shear motion, minimizing chronic immune responses and enabling recording and stimulation for months, and even years. The unique mechanical properties of flexible electronics also allow for intimate conformation to the brain, the spinal cord, peripheral nerves, and the retina. Moreover, flexible electronics enables optogenetic stimulation, microfluidic drug delivery, and neural activity imaging during electrical stimulation and recording. Finally, flexible electronics can enable neuron-type identification through analysis of high-fidelity recorded action potentials facilitated by its seamless integration with the neural circuitry. We argue that flexible electronics will play an increasingly important role in neuroscience studies and neurological therapies via the fabrication of neuromorphic devices on flexible substrates and the development of enhanced methods of neuronal interpenetration
Optimal anticipatory control as a theory of motor preparation: A thalamo-cortical circuit model.
No full textAcross a range of motor and cognitive tasks, cortical activity can be accurately described by low-dimensional dynamics unfolding from specific initial conditions on every trial. These "preparatory states" largely determine the subsequent evolution of both neural activity and behavior, and their importance raises questions regarding how they are, or ought to be, set. Here, we formulate motor preparation as optimal anticipatory control of future movements and show that the solution requires a form of internal feedback control of cortical circuit dynamics. In contrast to a simple feedforward strategy, feedback control enables fast movement preparation by selectively controlling the cortical state in the small subspace that matters for the upcoming movement. Feedback but not feedforward control explains the orthogonality between preparatory and movement activity observed in reaching monkeys. We propose a circuit model in which optimal preparatory control is implemented as a thalamo-cortical loop gated by the basal ganglia
Spatial analysis of the drivers, characteristics, and effects of forest fragmentation
No full textBuilding on the existing literature, this study examines whether specific drivers of forest fragmentation cause particular fragmentation characteristics, and how these characteristics can be linked to their effects on forest-dwelling species. This research uses Landsat remote imaging to examine the changing patterns of forests. It focuses on areas which have undergone a high level of a specific fragmentation driver, in particular either agricultural expansion or commodity-driven deforestation. Seven municipalities in the states of Rondônia and Mato Grosso in Brazil are selected as case study areas, as these states experienced a high level of commodity-driven deforestation and agricultural expansion respectively. Land cover maps of each municipality are created using the Geographical Information System software ArcGIS Spatial Analyst extension. The resulting categorical maps are input into Fragstats fragmentation software to calculate quantifiable fragmentation metrics for each municipality. To determine the effects that these characteristics are likely to cause, this study uses a literature review to determine how species traits affect their responses to forest fragmentation. Results indicate that, in areas that underwent agricultural expansion, the remaining forest patches became more complex in shape with longer edges and lost a large amount of core area. This negatively affects species which are either highly dispersive or specialist to core forest habitat. In areas that underwent commodity-driven deforestation, it was more likely that forest patches would become less aggregated and create disjunct core areas. This negatively affects smaller, sedentary animals which do not naturally travel long distances. This study is significant in that it links individual fragmentation drivers to their landscape characteristics, and in turn uses these to predict effects on species with particular traits. This information will prove useful for forest managers, particularly in the case study municipalities examined in this study, in deciding which species require further protection measures. The methodology could be applied to other drivers of forest fragmentation such as forest fires
Effect of Bearing Pressure on Liquefaction-Induced Settlement in Layered Soils
No full textEarthquake-induced liquefaction causes extensive damage to infrastructure. Soil liquefaction-induced effects can account for a significant proportion of damage such as the settlement of existing buildings on liquefiable soils. The influence of structures on the behavior of liquefiable soil is complex. In this paper, the effect of bearing pressure on liquefaction-induced settlement in layered soils was studied. Two 1 g shaking table tests, with different model buildings and bearing pressures, were conducted to establish the ultimate settlement of different structures in liquefiable layered soils. The results showed that as expected the settlement of the heavier building was larger than that of the lighter one. However, the settlement ratio of two buildings was smaller than the bearing pressure ratio. This study will be used as a benchmark for further testing on improving performance through the use of soil reinforcement methods
Evaluation of manifold representations of chemistry in stratified, swirl-stabilized flames
No full textThe validity of assuming that a simple, low-dimensional manifold can sufficiently accurately represent the chemical state in a turbulent flame is investigated. The experimental data from the Cambridge/Sandia stratified swirl burner working in nine different configurations are post-processed to explore the effects of coordinate, swirl flow ratio, and stratification factor on the conditionally-averaged reactive scalars. First, the mixture fraction and thermal progress variable are employed to construct a two-dimensional conditional manifold by using all of the data – regardless of the coordinate in the physical domain, swirl ratio, and stratification factor. Moreover, one-point, one-time measurements are utilized to compute the exact joint Probability Density Function (PDF) of the conditioning variables at each point. Having the conditional averages of temperature and mass fractions of CO2, CO, CH4, H2, and H2O in addition to the joint PDF of the conditioning variables, the low-dimensional manifold is applied to calculate the unconditional averages for each of the scalars. The mean values are also obtained by ensemble averaging all of the data available for each of the measuring points, and the discrepancies between the values calculated from the two approaches are reported in order to assess the validity of the assumptions underlying the low-dimensional chemistry representations. The results suggest that the two chosen conditioning variables are not sufficient to make the manifold independent of the real domain, so, the normalized total enthalpy is introduced as the third conditioning variable and the process repeated. Results obtained from the three-condition manifold demonstrate that the discrepancies for prediction of the reactive scalars, more significantly for CO2 and CO mass fractions, decrease when using the third condition. The discrepancies with three conditions show that a three-dimensional manifold is sufficient to assume the conditional averages are independent of swirl and stratification. A normalized accumulated discrepancy is used as a metric for each of the cases so one can see the overall effect of each assumption that is made for constructing the conditional manifold. Decoupling the manifold from the coordinate, swirl ratio, and stratification level makes it possible to obtain the filtered chemical source-terms from a static lookup table for many flames which will considerably reduce the computational cost for simulating turbulent reacting flows
Design, Fabrication and Performance Evaluation of Conductors in Tube Cables
No full textWith excellent mechanical properties and electromagnetic properties, compact superconducting cables are considered as potential candidates for large capacity power applications and fusion magnets. In this paper, the concept of a novel compact cable, conductors in tube (CIT) cable is introduced from the aspect of design, fabrication, and performance evaluation, respectively. The principal advantages of CIT cables are that the cable can release the residual stress created from the fabrication process, and the outer former of the cable can be used as both the supporter as well as the container of refrigerant liquid. Firstly, the topological structure and the detailed fabrication process of a CIT cable are presented. Then, a typical CIT cable is manufactured. The feasibility of this new structure is verified by its critical current test. Moreover, bending characteristics of CIT cables are evaluated and compared with Conductors on Round Core (CORC) cables from the aspect of both simulation and experiments. The superior bending performance enables it to be potential in the future compact magnet application
Modulated sparse superposition codes for the complex AWGN channel
No full textThis paper studies a generalization of sparse superposition codes (SPARCs) for communication over the complex additive white Gaussian noise (AWGN) channel. In a SPARC, the codebook is defined in terms of a design matrix, and each codeword is a generated by multiplying the design matrix with a sparse message vector. In the standard SPARC construction, information is encoded in the locations of the non-zero entries of the message vector. In this paper we generalize the construction and consider modulated SPARCs, where information is encoded in both the locations and the values of the non-zero entries of the message vector. We focus on the case where the non-zero entries take values from a phase-shift keying (PSK) constellation. We propose a computationally efficient approximate message passing (AMP) decoder, and obtain analytical bounds on the state evolution parameters which predict the error performance of the decoder. Using these bounds we show that PSK-modulated SPARCs are asymptotically capacity achieving for the complex AWGN channel, with either spatial coupling or power allocation. We also provide numerical simulation results to demonstrate the error performance at finite code lengths. These results show that introducing modulation to the SPARC design can significantly reduce decoding complexity without sacrificing error performance
Closing remarks
No full textThe TFAST project covered very wide range of knowledge starting from the basic research to more applied flow configurations. New knowledge generated in this project casts new light on the possibilities of flow control methods in reducing negative effects of shock wave interaction with laminar boundary layer. On the other hand application of flow control devices in the laminar boundary layer, just to inspire transition, is a valuable result. As usually in such complex flow structure the results are strongly case dependent, but the complexity of the presented approach shows great potential for improvements and provides a good basis for future research
Corrigendum to “Technology Roadmapping for mission-led agile hardware development: a case study of a commercial fusion energy start-up” Technological Forecasting & Social Change 158 (2020) 120064 (Technological Forecasting & Social Change (2020) 158, (S0040162519318281), (10.1016/j.techfore.2020.120064))
No full textInadvertently the authors omitted information in the caption of Figure 6, which should read: “Compact tokamak concept based on a collaboration between PPPL and Tokamak Energy (original image created by T. Brown of Princeton Plasma Physics Laboratory)”.The authors apologise for this omission. The updated email address of the first author is [email protected]