Design Space Exploration of Neural Network Activation Function Circuits

The widespread application of artificial neural networks has prompted researchers to experiment with FPGA and customized ASIC designs to speed up their computation. These implementation efforts have generally focused on weight multiplication and signal summation operations, and less on activation functions used in these applications. Yet, efficient hardware implementations of nonlinear activation functions like Exponential Linear Units (ELU), Scaled Exponential Linear Units (SELU), and Hyperbolic Tangent (tanh), are central to designing effective neural network accelerators, since these functions require lots of resources. In this paper, we explore efficient hardware implementations of activation functions using purely combinational circuits, with a focus on two widely used nonlinear activation functions, i.e., SELU and tanh. Our experiments demonstrate that neural networks are generally insensitive to the precision of the activation function. The results also prove that the proposed combinational circuit-based approach is very efficient in terms of speed and area, with negligible accuracy loss on the MNIST, CIFAR-10 and IMAGENET benchmarks. Synopsys Design Compiler synthesis results show that circuit designs for tanh and SELU can save between 3.13-7.69 and 4.45-8:45 area compared to the LUT/memory-based implementations, and can operate at 5.14GHz and 4.52GHz using the 28nm SVT library, respectively. The implementation is available at: https://github.com/ThomasMrY/ActivationFunctionDemo.Comment: 5 pages, 5 figures, 16 conferenc

Characterization of protein-protein interactions between the nucleocapsid protein and membrane protein of the avian infectious bronchitis virus

Avian infectious bronchitis virus (IBV) is one of the major viral respiratory diseases of chickens. Better understanding of the molecular mechanism of viral pathogenesis may contribute significantly to the development of prophylactic, therapeutic and diagnostic reagents as well as help in infection control. Avian IBV belongs to the Coronaviridaes and is similar to the other known coronaviruses. Previous studies have indicated that protein–protein interactions between nucleocapsid (N) and the membrane (M) proteins in coronavirus are related to coronavirus viral assembly. However, cases of IBV are seldom reported. In this study, yeast two-hybrid and  co-immunoprecipitation techniques were applied to investigate possible interactions between IBV N and M proteins. We found that interaction of the N and M proteins took place in vivo and the residues 168 – 225 of the M protein and the residues 150 - 210 of the N protein were determined to be involved in their interaction. These results may provide some useful information on the molecular mechanism of IBV’s N and M proteins, which will facilitate therapeutic strategies aiming at the disruption of the association between membrane and nucleocapsid proteins and indicate a new drug target for IBV.Key words: Co-immunoprecipitation, membrane protein, nucleocapsid protein, protein-protein interaction, yeast two-hybrid

Film-through large perovskite grains formation via a combination of sequential thermal and solvent treatment

Organic–inorganic halide perovskites have recently attracted strong research interest for fabrication of high-performance, lowcost photovoltaic devices. Recently, we reported a highly reproducible procedure to fabricate high-performance organic–inorganic halide perovskite solar cells. This procedure, based on a onestep, solvent-induced, fast deposition-crystallization method, involves the use of sec-butyl alcohol as a new solvent to induce the CH3NH3PbI3 fast crystallization deposition. In the present study, we propose a reproducible fabrication method to prepare both flat and large-grain perovskite film by adding a pre-annealing step to strengthen the perovskite nucleation, aiming to facilitate the excess CH3NH3I and solvent removal in the sec-butyl alcohol soaking process, in which all films with thickness between 420 nm and 1µm performed uniformly. The best performing planar device obtained with this procedure had an efficiency of 17.2% under AM 1.5G illumination and an average power conversion efficiency of 16.2 ± 0.5%. We also analyzed the efficiency of halide perovskite planar solar cells as a function of the perovskite film thickness; the efficiency dropped only slightly to 15.7% when the perovskite film thickness was increased to 1µm

Glycolysis-Related Gene Expression Profiling Screen for Prognostic Risk Signature of Pancreatic Ductal Adenocarcinoma

Objective: Pancreatic ductal adenocarcinoma (PDAC) is highly lethal. Although progress has been made in the treatment of PDAC, its prognosis remains unsatisfactory. This study aimed to develop novel prognostic genes related to glycolysis in PDAC and to apply these genes to new risk stratification.Methods: In this study, based on the Cancer Genome Atlas (TCGA) PAAD cohort, the expression level of glycolysis-related gene at mRNA level in PAAD and its relationship with prognosis were analyzed. Non-negative matrix decomposition (NMF) clustering was used to cluster PDAC patients according to glycolytic genes. Prognostic glycolytic genes, screened by univariate Cox analysis and LASSO regression analysis were established to calculate risk scores. The differentially expressed genes (DEGs) in the high-risk group and the low-risk group were analyzed, and the signal pathway was further enriched to analyze the correlation between glycolysis genes. In addition, based on RNA-seq data, CIBERSORT was used to evaluate the infiltration degree of immune cells in PDAC samples, and ESTIMATE was used to calculate the immune score of the samples.Results: A total of 319 glycolysis-related genes were retrieved, and all PDAC samples were divided into two clusters by NMF cluster analysis. Survival analysis showed that PDAC patients in cluster 1 had shorter survival time and worse prognosis compared with cluster 2 samples (P < 0.001). A risk prediction model based on 11 glycolysis genes was constructed, according to which patients were divided into two groups, with significantly poorer prognosis in high-risk group than in low-risk group (P < 0.001). Both internal validation and external dataset validation demonstrate good predictive ability of the model (AUC = 0.805, P < 0.001; AUC = 0.763, P < 0.001). Gene aggregation analysis showed that DEGs highly expressed in high-risk group were mainly concentrated in the glycolysis level, immune status, and tumor cell proliferation, etc. In addition, the samples in high-risk group showed immunosuppressed status and infiltrated by relatively more macrophages and less CD8+T cell.Conclusions: These findings suggested that the gene signature based on glycolysis-related genes had potential diagnostic, therapeutic, and prognostic value for PDAC

π-Bridge Effect on Symmetric Carbazole-Based Small Molecules for Realizing Ultraviolet Fluorescent Emission

A series of symmetric carbazole derivatives (CzP-H, CzP-CN, CzP-Me, and CzP-OMe), which comprise electron-donating and electron-drawing groups appending on a phenyl core, was synthesized and characterized in detail. These compounds exhibit excellent thermal stabilities, with thermal decomposition temperatures exceeding 400 °C. From the fluorescent spectra in film, CzP-H, CzP-Me, and CzP-OMe showed UV to blue-violet emission, with peaks at 396 nm, 402 nm, and 392 nm, respectively. The E00 energies of CzP-H, CzP-CN, CzP-Me, and CzP-OMe were 3.39 eV, 2.83 eV, 3.50 eV, and 3.35 eV, respectively. From the electrochemical measurements, the highest occupied molecular orbital (HOMOs) energy levels were −5.30 eV, −5.64 eV, −5.46 eV, and −5.24 eV for CzP-H, CzP-CN, CzP-Me, and CzP-OMe, respectively. Through calculations from HOMO energy levels and E00 energies, the lowest unoccupied molecular orbital (LUMOs) energy levels of CzP-H, CzP-CN, CzP-Me, and CzP-OMe were −1.91 eV, −2.81 eV, −1.96 eV, and −1.89 eV, respectively. Therefore, the introduction of different substitutes in phenyl cores would distinctly affect the photophysical properties. These results indicate that the prepared carbazole derivatives could be potential candidates for realizing ultraviolet or blue-violet emission

Development of a Conventional RT-PCR Assay for Rapid Detection of Porcine Deltacoronavirus with the Same Detection Limit as a SYBR Green-Based Real-Time RT-PCR Assay

Porcine deltacoronavirus (PDCoV) is a newly discovered coronavirus, which belongs to the family Coronaviridae. It causes watery diarrhea, vomiting, and dehydration in newborn piglets. A sensitive RT-PCR method is urgently required to detect PDCoV infection. In this study, we developed and evaluated a conventional RT-PCR assay and a SYBR green-based real-time RT-PCR assay that targeted the PDCoV n gene. Both assays are specific and have the same limit of detection at 2 × 101 copies of RNA molecules per reaction. Eighty-four clinical samples were subjected to both conventional RT-PCR and real-time RT-PCR, and the same positive rate (41.7%) was achieved, which was much higher than the positive rate (26.2%) using a previously described one-step RT-PCR technique. In summary, a conventional RT-PCR technique was successfully established for the detection of PDCoV with the same detection limit as a SYBR green-based real-time RT-PCR assay

Fluidized Bed Two-Stage Gasification Process for Clean Fuel Gas Production from Herb Residue: Fundamentals and Demonstration

A new two-stage gasification process, decoupling complex biomass gasification from biomass pyrolysis and char gasification, has been proposed for the production of clean industrial fuel gas. In this work, Chinese herb residues will be used as raw material, and the fundamental studies and demonstration of this process were conducted on an externally heated laboratory two-stage gasification setup and an industrial demonstration plant, respectively. The fundamental studies found that the appropriate operation of the upstream fluidized bed (FB) pyrolyzer occurred at 700 degrees C and the suitable conditions for effective tar removal in the downstream gasifier were as follows: 850 degrees C, an equivalent ratio of air (ER) at 0.04, and a retention time of tar containing fuel gas above 0.9 s. On the basis of these fundamental data, an autothermal demonstration plant treating 600 kg of herb residue per hour was built and successfully commissioned for its continuous running to verify the technology feasibility. The running data showed that the tar content in the gasified gas was as low as 400 mg/Nm(3) at temperatures of 700 degrees C for the FB pyrolyzer and 850 degrees C for the transport fluidized bed gasifier. The produced fuel gas had a heating value of similar to 5.0 MJ/Nm(3). All of these displayed well-the technical characteristics and demonstrated the process feasibility for this newly developed gasification technology.</p