Temperature-aware clock tree synthesis considering spatiotemporal hot spot correlations

Temperature variation in microprocessors is a workload dependent problem. In such a design, the clock skew should be minimized with respect to temperature variation. Existing work has studied clock tree embedding perturbation consid-ering time variant temperature variation. There is no existing method that can reduce skew variation. This paper develops an efficient yet effective simultaneous hotspot avoid embedding and thermal aware routing (TMST) method, where hotspot embedding avoid tree topology located in area with high temperature possibility and thermal aware routing reduce skew in tree path with more smooth temperature area. With a thermally tolerable tree structure, our method can reduce not only delay skew but also skew variation (skew violation range). Compared with existing temperature-aware clock tree method, our TMST solution reduces skew variation by 2X compared with the Greedy-DME (GDME) method of Edahiro and existing thermal aware clock synthesis TACO and PECO. With the scale from 100 down to 1 temperature maps, our TMST also guarantees the smallest wire length overflow. TMST reduces the worst case skew up to 4X than PECO and 5X than TACO. I

Responses of Karenia mikimotoi to allelochemical linoleic acid: Growth inhibition, photosynthetic damage, oxidative stress and cell apoptosis

Linoleic acid (LA), a potentially algae-inhibiting chemical released by macroalgae, has been shown to hinder the growth of numerous bloom-forming species. The allelopathic effects of LA (varying from 100 μg/L to 900 μg/L) on harmful microalgae K. mikimotoi were examined using population growth dynamics and physiological levels of K. mikimotoi. LA (>500 μg/L) strongly inhibited algal growth with most cells halted at the S and G2 phases and an evident drop in photosynthetic pigments (chlorophyll a (chl a), chlorophyll c (chl c) and carotenoids). Furthermore, chlorophyll fluorescence parameters such as Fv/Fm, PI, ETo/RC showed a declining trend whereas ABS/RC, DIo/RC, TRo/RC showed an increasing trend with increasing LA exposure concentrations. The level of intracellular reactive oxygen species (ROS) was considerably higher, indicating that LA promoted oxidative stress in K. mikimotoi. Excessive ROS promoted apoptosis in K. mikimotoi, which was noted by increased activity of caspase-3, caspase-9, and flow cytometry (FCM) data. Furthermore, N-acetylcysteine (NAC) and N-Acetyl-Asp-Glu-Val-Asp-CHO (Ac-DEVD-CHO) lowered the apoptotic rates of the LA-treated algal cells, indicating that the aforementioned inhibitors delayed K. mikimotoi apoptosis under LA treatment. To summarize, cell cycle arrest of K. mikimotoi is less sensitive to ROS, but the overproduction of ROS generated by LA activated caspase-3 and caspase-9, which further promoted the apoptosis of K. mikimotoi. This research showed that LA might have great potential and application prospects in controlling the outbreak of harmful algae

Anisotropic ultrafast spin/valley dynamics in WTe2 films

WTe2 Weyl semimetal hosts the natural broken inversion symmetry and strong spin orbit coupling, making it promising for exotic spin/valley dynamics within a picosecond timescale. Here, we unveil an anisotropic ultrafast spin/valley dynamics in centimeter-scale, single-crystalline Td-WTe2 films using a femtosecond pump-probe technique at room temperature. We observe a transient (~0.8 ps) intra-valley transition and a subsequent polarization duration (~5 ps) during the whole spin/valley relaxation process. Furthermore, the relaxation exhibits the remarkable anisotropy of approximately six-fold and two-fold symmetries due to the intrinsic anisotropy along the crystalline orientation and the extrinsic matrix element effect, respectively. Our results offer a prospect for the ultrafast manipulation of spin/valleytronics in topological quantum materials for dissipationless high-speed spin/valleytronic devices.Comment: 21 pages, 4 figure

Sensitive and Ultrabroadband Phototransistor Based on Two-Dimensional Bi2O2Se Nanosheets

Bi2O2Se, a high-mobility and air-stable 2D material, has attracted substantial attention for application in integrated logic electronics and optoelectronics. However, achieving an overall high performance over a wide spectral range for Bi2O2Se-based devices remains a challenge. A broadband phototransistor with high photoresponsivity (R) is reported that comprises high-quality large-area (≈180 µm) Bi2O2Se nanosheets synthesized via a modified chemical vapor deposition method with a face-down configuration. The device covers the ultraviolet (UV), visible (Vis), and near-infrared (NIR) wavelength ranges (360–1800 nm) at room temperature, exhibiting a maximum R of 108 696 A W−1 at 360 nm. Upon illumination at 405 nm, the external quantum efficiency, R, and detectivity (D*) of the device reach up to 1.5 × 107%, 50055 A W−1, and 8.2 × 1012 Jones, respectively, which is attributable to a combination of the photogating, photovoltaic, and photothermal effects. The devices reach a −3 dB bandwidth of 5.4 kHz, accounting for a fast rise time (τrise) of 32 µs. The high sensitivity, fast response time, and environmental stability achieved simultaneously in these 2D Bi2O2Se phototransistors are promising for high-quality UV and IR imaging applications

DNA Immunization with Fusion of CTLA-4 to Hepatitis B Virus (HBV) Core Protein Enhanced Th2 Type Responses and Cleared HBV with an Accelerated Kinetic

BACKGROUND: Typically, DNA immunization via the intramuscular route induces specific, Th1-dominant immune responses. However, plasmids expressing viral proteins fused to cytotoxic T lymphocyte antigen 4 (CTLA-4) primed Th2-biased responses and were able to induced effective protection against viral challenge in the woodchuck model. Thus, we addressed the question in the mouse model how the Th1/Th2 bias of primed immune responses by a DNA vaccine influences hepatitis B virus (HBV) clearance. PRINCIPAL FINDINGS: Plasmids expressing HBV core protein (HBcAg) or HBV e antigen and HBcAg fused to the extracellular domain of CTLA-4 (pCTLA-4-HBc), CD27, and full length CD40L were constructed. Immunizations of these DNA plasmids induced HBcAg-specific antibody and cytotoxic T-cell responses in mice, but with different characteristics regarding the titers and subtypes of specific antibodies and intensity of T-cell responses. The plasmid pHBc expressing HBcAg induced an IgG2a-dominant response while immunizations of pCTLA-4-HBc induced a balanced IgG1/IgG2a response. To assess the protective values of the immune responses of different characteristics, mice were pre-immunized with pCTLA-4-HBc and pHBc, and challenged by hydrodynamic injection (HI) of pAAV/HBV1.2. HBV surface antigen (HBsAg) and DNA in peripheral blood and HBcAg in liver tissue were cleared with significantly accelerated kinetics in both groups. The clearance of HBsAg was completed within 16 days in immunized mice while more than 50% of the control mice are still positive for HBsAg on day 22. Stronger HBcAg-specific T-cell responses were primed by pHBc correlating with a more rapid decline of HBcAg expression in liver tissue, while anti-HBs antibody response developed rapidly in the mice immunized with pCTLA-4-HBc, indicating that the Th1/Th2 bias of vaccine-primed immune responses influences the mode of viral clearance. CONCLUSION: Viral clearance could be efficiently achieved by Th1/Th2-balanced immune response, with a small but significant shift in T-cell and B-cell immune responses

A Hybrid Causal Structure Learning Algorithm for Mixed-Type Data

Inferring the causal structure of a set of random variables is a crucial problem in many disciplines of science. Over the past two decades, various approaches have been pro- posed for causal discovery from observational data. How- ever, most of the existing methods are designed for either purely discrete or continuous data, which limit their practical usage. In this paper, we target the problem of causal structure learning from observational mixed-type data. Although there are a few methods that are able to handle mixed-type data, they suffer from restrictions, such as linear assumption and poor scalability. To overcome these weaknesses, we formulate the causal mechanisms via mixed structure equation model and prove its identifiability under mild conditions. A novel locally consistent score, named CVMIC, is proposed for causal directed acyclic graph (DAG) structure learning. Moreover, we propose an efficient conditional independence test, named MRCIT, for mixed-type data, which is used in causal skeleton learning and final pruning to further improve the computational efficiency and precision of our model. Experimental results on both synthetic and real-world data demonstrate that our proposed hybrid model outperforms the other state-of-the-art methods. Our source code is available at https://github.com/DAMO-DI-ML/AAAI2022-HCM