Quasi-Whittaker modules for the Schr\"odinger algebra

In this paper, we construct a new class of modules for the Schr\"{o}dinger algebra \mS, called quasi-Whittaker module. Different from \cite{[ZC]}, the quasi-Whittaker module is not induced by the Borel subalgebra of the Schr\"{o}dinger algebra related with the triangular decomposition, but its Heisenberg subalgebra \mH. We prove that, for a simple \mS-module $V$, $V$ is a quasi-Whittaker module if and only if $V$ is a locally finite \mH-module; Furthermore, we classify the simple quasi-Whittaker modules by the elements with the action similar to the center elements in U(\mS) and their quasi-Whittaker vectors. Finally, we characterize arbitrary quasi-Whittaker modules.Comment: 17 page

竞争战略与美国特朗普政府对华政策调整

The Competitive Strategy, which helped the US gain great advantages in competition with its major rivals, has played an important part in US foreign policy for a long time. The full use of it in the cold war with Soviet Union is the most significant case. In recent years, under the promotion of the academic circle and the strategic circle, the concept of a competitive strategy is rapidly returning into the US foreign strategy, becoming an important theoretical basis for the adjustment of the Trump Administration's China policy. Recently, the United States has taken multi-domain actions simultaneously to strengthen the strategic competition and containment policies against China, such as mobilizing public opinion, provoking China-related issues, creating new weaponized legislation and even increasingly making use of Taiwan and Hong Kong to contain China. Under this competition situation, China must balance the whole picture and the critical point, make proper adjustments accordingly while sticking to their bottom-line priorities. Only in this way can China relieve the pressure and gain the initiative to effectively manage competition with the US. During this course, China should make more effort in improving its capacity and level of governance, strengthening the domestic foundation of competition against the US. Meanwhile, China should also actively adapt itself to the changing world and make full use of the situation to guide the direction of the China-US relationship. Key Words: Strategic competition; China-US relationship; Competition management; Counterbalancing ability 竞争战略在美国对外政策中占有重要地位，尤其在和主要对手的较量中，美国善于运用这一战略并曾收到较大成效，其中最显著的案例就是在美苏冷战中的充分运用。在美国学界和战略界的推动下，竞争战略理念在美对外战略中快速回归，也成为特朗普政府对华政策调整的重要理论依据。近来美国不断强化对华战略竞争与遏制的舆论动员，设置涉华议题，为强化对华战略竞争与遏制提供法律依据，并在等多个领域出手，全面强化对华战略竞争压力，甚至更多地利用台湾、香港局势的发展变化来牵制中国。面对咄咄逼人的竞争态势，中国既需抓住关键也需把握全局，既要坚守底线也要进退有据，有效管控中美竞争，化解战略压力拓展战略主动；而在竞争中更须切实提升国家治理能力和水平，筑牢战略竞争的国内基础，同时也要积极顺应世界变局，因势利导努力牵引中美关系的发展方向。 【关键词】战略竞争 中美关系 竞争管控 制衡能力 因势利

Investigating mechanism of inclined CPT in granular ground using DEM

Abstract. This paper presents an investigation on mechanism of the inclined 1 cone penetration test (CPT) using the numerical discrete element method (DEM). 2 A series of penetration tests with the penetrometer inclined at different angles 3 (i.e., 0°,15°, 30°, 45° and 60°) were numerically performed under µ=0.0 and 4 µ=0.5, where µ is the frictional coefficient between the penetrometer and the soil. 5 The deformation patterns, displacements of soil particles adjacent to the cone tip, 6 velocity fields, rotations of the principal stresses and the averaged pure rotation 7 rate (APR) were analyzed. Special focus was placed on the effect of friction. The 8 DEM results showed that soils around the cone tip experienced complex 9 displacement paths at different positions as the inclined penetration proceeded, 10 and the friction only had significant effects on the soils adjacent to the 11 penetrometer side and tip. Soils exhibited characteristic velocity fields 12 corresponding to three different failure mechanisms and the right side was easier 13 to be disturbed by friction. Friction started to play its role when the tip approached 14 the observation points, while it had little influence on rotation rate. The 15 normalized tip resistance (q c = f /σ v0 ) increased with friction as well as inclination 16 angle. The relationship between q c and relative depth (y/R) can be described as q c 17 =a×(y/R) -b , with parameters a and b dependent on penetration direction. The 18 normalized resistance perpendicular to the penetrometer axis q p increases with the 19 inclination angle, thus the inclination angle should be carefully selected to ensure 20 the penetrometer not to deviate from its original direction or even be broken in 21 real tests. 2

Frequency-revealing attacks against Frequency-hiding Order-preserving Encryption

Order-preserving encryption (OPE) allows efficient comparison operations over encrypted data and thus is popular in encrypted databases. However, most existing OPE schemes are vulnerable to inference attacks as they leak plaintext frequency. To this end, some frequency-hiding order-preserving encryption (FH-OPE) schemes are proposed and claim to prevent the leakage of frequency. FH-OPE schemes are considered an important step towards mitigating inference attacks. Unfortunately, there are still vulnerabilities in all existing FH-OPE schemes. In this work, we revisit the security of all existing FH-OPE schemes. We are the first to demonstrate that plaintext frequency hidden by them is recoverable. We present three ciphertext-only attacks named frequency-revealing attacks to recover plaintext frequency. We evaluate our attacks in three real-world datasets. They recover over 90% of plaintext frequency hidden by any existing FH-OPE scheme. With frequency revealed, we also show the potentiality to apply inference attacks on existing FH-OPE schemes. Our findings highlight the limitations of current FH-OPE schemes. Our attacks demonstrate that achieving frequency-hiding requires addressing the leakages of both non-uniform ciphertext distribution and insertion orders of ciphertexts, even though the leakage of insertion orders is always ignored in OPE

bpMRI and mpMRI for detecting prostate cancer: A retrospective cohort study

BackgroundWe aimed to compare the detection rates of prostate cancer (PCa) and clinically significant prostate cancer(csPCa) by biparametric (bp-) and multiparameter magnetic resonance imaging (mpMRI).Materials and MethodsA total of 699 patients who underwent transperineal prostate biopsy in the Department of Urology, the Second Affiliated Hospital of Nantong University from January 2018 to December 2021 were retrospectively reviewed. Multivariate analysis was used to explore the influencing factors associated with the detection rates of PCa and csPCa. According to MRI examination before biopsy, the patients were divided into bpMRI group and mpMRI group. The detection rates of PCa and csPCa by bpMRI and mpMRI were compared. Furthermore, stratified analysis was performed for patients in these two groups to compare the detection rates of PCa and csPCa at different tPSA intervals, different prostate volume (PV) intervals and different PI-RADS V2 scores.ResultsA total of 571 patients were finally analyzed in this study after exclusion, and the overall detection rate of PCa was 54.5%. Multivariate analysis showed that patient age, tPSA level, prostate volume and PI-RADS V2 score were independent risk factors affecting the detection rates of PCa and csPCa. The detection rates of PCa and csPCa by bpMRI and mpMRI were comparable (51.3% vs. 57.9%, 44.0% vs. 48.0%, both P > 0.05), with no statistical significance. In the tPSA 10–20 ng/ml interval, the detection rates of PCa (59.72% vs. 40.35%, P = 0.011) and csPCa (51.39% vs. 28.82%, P = 0.005) by mpMRI were significantly higher than those by bpMRI, while in other tPSA interval (tPSA < 4 ng/ml, 4–10 ng/ml, 20–100 ng/ml), different PVs (≤30 ml, 30–60 ml, >60 ml) and different PI-RADS V2 scores (3, 4, and 5), the detection rates of PCa and csPCa were comparable between the two groups.ConclusionFor detecting PCa and csPCa, bpMRI and mpMRI had similar diagnostic efficacies, whereas mpMRI detected more PCa and csPCa in the tPSA interval of 10–20 ng/ml