213 research outputs found

    Analysis of corrections to the eikonal approximation

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    Various corrections to the eikonal approximations are studied for two- and three-body nuclear collisions with the goal to extend the range of validity of this approximation to beam energies of 10 MeV/nucleon. Wallace's correction does not improve much the elastic-scattering cross sections obtained at the usual eikonal approximation. On the contrary, a semiclassical approximation that substitutes the impact parameter by a complex distance of closest approach computed with the projectile-target optical potential efficiently corrects the eikonal approximation. This opens the possibility to analyze data measured down to 10 MeV/nucleon within eikonal-like reaction models.Comment: 10 pages, 8 figure

    Cache attack on MISTY1

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    Side-channel attacks exploit information from physical implementations of cryptographic systems. Cache attacks have improved at recovering information by combining observations of the victim\u27s cache access and knowledge of the cipher’s structure. Cache attacks have been implemented for most Feistel- and SPN-structured block cipher algorithms, but the security of algorithms for special structures has seen little attention. We perform a Flush+Reload attack on MISTY1, a class of block cipher with a recursive structure. The function is performed before the plaintext input S-box and after the ciphertext output S-box, making it difficult to attack the first and last rounds. However, the key scheduling part of MISTY1 leaks many bits of the key, which, together with the leakage of partial bits of the round key during encryption, is sufficient to recover it. We design an algorithm that can recover the MISTY1 128-bit key after observing encryption one time, and then use leakage during encryption to reduce its complexity. We experiment on 32- and 64-byte cache line environments. An adversary need observe as little as 5 encryptions to recover the 128-bit key in 0.035 second in the first case, and 10 encryptions to recover the key in 2.1 hours in the second case

    Virtual Planning and 3D printing modeling for mandibular reconstruction with fibula free flap

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    This study was to evaluate the use of virtual planning and 3D printing modeling in mandibular reconstruction and compare the operation time and surgical outcome of this technique with conventional method. Between 2014 and 2017, 15 patients underwent vascularized fibula flap mandibular reconstruction using virtual planning and 3D printing modeling. Titanium plates were pre-bent using the models and cutting guides were used for osteotomies. 15 patients who underwent mandibular reconstruction using fibula flap without aid of virtual planning and 3D printing models were selected as control group. The operation time was recorded and compared in two groups. Accuracy of reconstruction was measured by superimposing the preoperative image onto the postoperative image of mandible. The selected bony landmark, distance and angle were measured. The mean total operation time and reconstruction time were 1.60±0.37 and 5.54±0.50 hours in computer-assisted group, respectively; These were 2.58±0.45 and 6.54±0.70 hours in conventional group, respectively. Both operation time and reconstruction time were shorter in computer-assisted group. The difference between the preoperative and postoperative intercondylar distances, intergonial angle distances, anteroposterior distances and gonial angles were 2.92±1.15 and 4.48±1.41mm, 2.93±1.19 and 4.79±1.48mm, 4.31±1.24 and 5.61±1.41mm, 3.85±1.68° and 5.88±2.12° in the computer-assisted and conventional group, respectively. The differences between the preoperative and postoperative mandible is smaller in the computer-assisted group. Virtual planning and 3D printing modeling have the potential to increase mandibular reconstruction accuracy and reduce operation time. we believe that this technology for mandibular reconstruction in selected patients will become a used method and improve the quality of reconstruction

    Fabrication of Crack-free Photonic Crystal Films on Superhydrophobic Nanopin Surface

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    厦门大学生物仿生及软物质研究院林友辉副教授以及院长刘向阳教授在利用超疏水基底改善胶体小球自组装研究方向取得进展。 目前通过胶体小球自组装方法已构筑了许多复杂却高度有序的光子晶体。但是胶体小球在形成有序结构过程中会不可避免的产生收缩和应力,该方法通常会导致裂纹和缺陷的形成,降低了光子晶体的光学质量,也同时限制了其进一步的应用。 在该研究中,作者基于以上的研究现状,以纳米针状的超疏水表面为基底,来改善胶体小球的自组装,可以减少甚至消除大尺度的裂纹的效果。基于该原理,最后成功制备出厘米级别无裂纹的光子晶体薄膜。【Abstract】sed on their superior optical performance, photonic crystals (PCs) have been investigated as excellent candidates for widespread applications including sensors, displays, separation processes, and catalysis. However, fabrication of large-area PC assemblies with no defects and structurally controllable is still a tough task. Herein, we develop an effective strategy for preparing centimeter-scale crack-free photonic crystals films by the combined effects of soft assembly and superhydrophobic nanopin surfaces. Owing to its large contact angle and low adhesive force on the superhydrophobic substrate, the colloidal suspension exhibits a continuous retraction of the three-phase (gas−liquid−solid) contact line(TCL) in the process of solvent (water molecules) evaporation. The constantly receding TCL can bring the colloidal spheres closer to each other, which could timely close the gaps due to the loss of water molecules. As a result, close-packed and well-ordered assembly structures can be easily obtained. We expect that this work may pave the way to utilize novel superhy drophobic materials for designing and developing high-quality PCs and to apply PCs in different fields.This work is financially supported by National Nature Science Foundation (Nos. 21401154,U1405226), 111 project (B16029), Guangdong Natural Science Foundation (2014A030310005),the Fundamental Research Funds for the Central Universities of China (Nos. 20720170011,20720140528), Ph.D. Programs Foundation of Ministry of Education of China(20130121110018), Fujian Provincial Department of Science & Technology (2014H6022).X.Y.L.'s primary affiliation is the Department of Physics, National University of Singapore

    Continuous low-dose cyclophosphamide plus prednisone in the treatment of relapsed and refractory multiple myeloma with severe complications

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    Background/objectiveWe retrospectively analyzed the effective and safety of continuous low-dose cyclophosphamide combined with prednisone (CP) in relapsed and refractory multiple myeloma (RRMM) patients with severe complications.MethodsA total of 130 RRMM patients with severe complications were enrolled in this study, among which 41 patients were further given bortezomib, lenalidomide, thalidomide or ixazomib on the basis of CP regimen (CP+X group). The response to therapy, adverse events (AEs), overall survival (OS) and progression-free survival (PFS) were recorded.ResultsAmong the 130 patients, 128 patients received therapeutic response assessment, with a complete remission rate (CRR) and objective response rate (ORR) of 4.7% and 58.6%, respectively. The median OS and PFS time were (38.0 ± 3.6) and (22.9±5.2) months, respectively. The most common AEs were hyperglycemia (7.7%), pneumonia (6.2%) and Cushing’s syndrome (5.4%). In addition, we found the pro-BNP/BNP level was obviously decreased while the LVEF (left ventricular ejection fraction) was increased in RRMM patients following CP treatment as compared with those before treatment. Furthermore, CP+X regimen further improved the CRR compared with that before receiving the CP+X regimen (24.4% vs. 2.4%, P=0.007). Also, both the OS and PFS rates were significantly elevated in patients received CP+X regimen following CP regimen as compared with the patients received CP regimen only.ConclusionThis study demonstrates the metronomic chemotherapy regimen of CP is effective to RRMM patients with severe complications

    Sciences for The 2.5-meter Wide Field Survey Telescope (WFST)

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    The Wide Field Survey Telescope (WFST) is a dedicated photometric survey facility under construction jointly by the University of Science and Technology of China and Purple Mountain Observatory. It is equipped with a primary mirror of 2.5m in diameter, an active optical system, and a mosaic CCD camera of 0.73 Gpix on the main focus plane to achieve high-quality imaging over a field of view of 6.5 square degrees. The installation of WFST in the Lenghu observing site is planned to happen in the summer of 2023, and the operation is scheduled to commence within three months afterward. WFST will scan the northern sky in four optical bands (u, g, r, and i) at cadences from hourly/daily to semi-weekly in the deep high-cadence survey (DHS) and the wide field survey (WFS) programs, respectively. WFS reaches a depth of 22.27, 23.32, 22.84, and 22.31 in AB magnitudes in a nominal 30-second exposure in the four bands during a photometric night, respectively, enabling us to search tremendous amount of transients in the low-z universe and systematically investigate the variability of Galactic and extragalactic objects. Intranight 90s exposures as deep as 23 and 24 mag in u and g bands via DHS provide a unique opportunity to facilitate explorations of energetic transients in demand for high sensitivity, including the electromagnetic counterparts of gravitational-wave events detected by the second/third-generation GW detectors, supernovae within a few hours of their explosions, tidal disruption events and luminous fast optical transients even beyond a redshift of 1. Meanwhile, the final 6-year co-added images, anticipated to reach g about 25.5 mag in WFS or even deeper by 1.5 mag in DHS, will be of significant value to general Galactic and extragalactic sciences. The highly uniform legacy surveys of WFST will also serve as an indispensable complement to those of LSST which monitors the southern sky.Comment: 46 pages, submitted to SCMP

    Efficacy of early prone or lateral positioning in patients with severe COVID-19: a single-center prospective cohort

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    Abstract Background Position intervention has been shown to improve oxygenation, but its role in non-invasively ventilated patients with severe COVID-19 has not been assessed. The objective of this study was to investigate the efficacy of early position intervention on non-invasively ventilated patients with severe COVID-19. Methods This was a single-center, prospective observational study in consecutive patients with severe COVID-19 managed in a provisional ICU at Renmin Hospital of Wuhan University from 31 January to 15 February 2020. Patients with chest CT showing exudation or consolidation in bilateral peripheral and posterior parts of the lungs were included. Early position intervention (prone or lateral) was commenced for &amp;gt; 4 hours daily for 10 days in these patients, while others received standard care. Results The baseline parameters were comparable between the position intervention group (n = 17) and the standard care group (n = 35). Position intervention was well-tolerated and increased cumulative adjusted mean difference of SpO2/FiO2 (409, 95% CI 86 to 733) and ROX index (26, 95% CI 9 to 43) with decreased Borg scale (−9, 95% CI −15 to −3) during the first 7 days. It also facilitated absorption of lung lesions and reduced the proportion of patients with high National Early Warning Score 2 (≥ 7) on days 7 and 14, with a trend toward faster clinical improvement. Virus shedding and length of hospital stay were comparable between the two groups. Conclusions This study provides the first evidence for improved oxygenation and lung lesion absorption using early position intervention in non-invasively ventilated patients with severe COVID-19, and warrants further randomized trials. </jats:sec
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