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Electromagnetically induced transparency and electromagnetically induced absorption in Y-type system

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Chinese physics B 2020年第5期29卷 303-310页

作者： Kalan Mal Khairul Islam Suman Mondal Dipankar Bhattacharyya Amitava Bandyopadhyay Department of physics Suri Vidyasagar CollegeSuriPIN 731101West BengalIndia Departmet of Physics Visva-BharatiSantiniketanPIN 731235West BengalIndia Department of physics Santipur CollegeSantipurPIN 741404West BengalIndia

The propagation of a probe field through a four-level Y-type atomic system is described in the presence of two additional coherent radiation fields,namely,the control field and the coupling field.An expression for the probe response is derived analytically from the optical Bloch equations under steady state condition to study the absorptive properties of the system under probe field propagation through an ensemble of stationary atoms as well as in a Doppler broadened atomic vapor medium.The most striking result is the conversion of electromagnetically induced transparency(EIT)into electromagnetically induced absorption(EIA)as we start switching from weak probe regime to strong probe regime.The dependence of this conversion on residual Doppler averaging due to wavelength mismatch is also shown by choosing the coupling transition as a Rydberg transition.

关键词： Y-type system density matrix method electromagnetically induced transparency(EIT) electromagnetically induced absorption(EIA)

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Functional recovery following traumatic spinal cord injury mediated by a unique polymer scaffold seeded with neural stem cells and Schwann cells

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Chinese Medical Journal 2010年第17期123卷 2424-2431页

作者： CHEN Gang HU Yan-rong WAN Hong XIA Lei LI Jun-hua YANG Fei QU Xue WANG Shen-guo WANG Zhong-cheng departmet of Neurosurgery Xinjiang Autonomous Region People Hospital Urumqi 830001 China Research Center of Clinical Medicine Xinjiang Autonomous Region People Hospital Urumqi 830001 China Beijing Neurosurgical Institute Beijing 100050 China State Key Laboratory of Polymer physics & Chemistry Institute of Chemistry The Chinese Academy of Sciences Beijing 100080 China

Background The most important objective of transplant studies in the injured spinal cord has been to provide a favorable environment for axonal growth. Moreover, the continuing discovery of new grafts is providing new potentially interesting transplant candidates. Our purpose was to observe the morphological and functional repair effects of the co-transplantation of neural stem cell （NSC）, Schwann ceils （SCs） and poly lactide-co-glycolide acid （PLGA） on the spinal cord injury of rats.Methods A scaffold of PLGA was fabricated. NSCs and SCs were cultured, with the NSCs labeled with 5-bromodeoxyuridine, and the complex of NSC/PLGA or NSC＋SCs/PLGA were constructed. Thirty-six Wistar rats were randomly divided into three groups： group A （transplantation of PLGA）, group B （transplantation of NSC/PLGA） and group C （transplantation of NSC＋SCs/PLGA）. The 3 mm length of the right hemicord was removed under the microscope in all rats. The PLGA or the complex of PLGA-celIs were implanted into the injury site. Basso-Beattie-Bresnahan （BBB）locomotion scores, motor and somatosensory evoked potential of lower limbs were examined to learn the rehabilitation of sensory and motor function at 4 weeks, 8 weeks, 12 weeks and 24 weeks after injury. All the recovered spinal cord injury （SCI） tissues were observed with HE staining, immunohistochemistry, and transelectronmicroscopy to identify the survival, migration and differentiation of the transplanted cells and the regeneration of neural fibres at 4 weeks, 8 weeks,12 weeks and 24 weeks after injury.Results （1） From 4 weeks to 24 weeks after injury, the BBB locomotion scores of cell-transplanted groups were better than those of the non-cell-transplanted group, especially group C （P 〈0.05）. The amplitudes of the somatosensory evoked potential （SEP） and motor-evoked potential （MEP） were improved after injury in groups B and C, but the amplitude of SEP and MEP at 4 weeks was lower than that at 12 weeks and 24 weeks after injury. Compared with group B, the amplitude of SEP and MEP in grou

关键词： spinal cord injuries neural stem cell Schwann cells poly lactide-co-glycolide acid transplantation

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Collective Band Structures in the Neutron-Rich ^(107,109)Ru Nuclei

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Chinese physics Letters 1998年第11期15卷 793-795页

作者：朱胜江甘翠云 J.H.Hamilton A.V.Ramayya B.R.S.Babu 萨哈伊 W.C.Ma 龙桂鲁邓景康朱凌燕李明杨利明 J.Komicki J.D.Cole R.Aryaeinejad Y.K.Dardenne M.W.Drigert J.O.Rasmussen M.A.Stoyer S.Y.Chu K.E.Gregorich M.F.Mohar S.G.Prussin I.Y.Lee N.R.Johnson F.K.McGowan Departmet of Physics Tsinghua UniversityBeijing 100084 Department of physics Vanderbilt UniversityNashvilleTN 37235USA Department of physics Mississippi State UniversityMS 39762USA Idaho National Engineering Laboratory Idaho FallsID 83415USA Lawrence Berkeley Laboratory BerkeleyCA 94720USA Oak Ridge National Laboratory Oak RidgeTN 37831USA

The levels in neutron-rich odd-A ^(107,109)Ru nuclei have been investigated by using γ -γ -and γ -γ -γ-coincidence studies of the prompt γ-rays from the spontaneous fission of 252Cf. The ground state bands and the negative parity bands are identified and expanded in both nuclei. Triaxial rotor plus particle model calculations indicate the ground state bands originate from v(d_(5/2)+g_(7/2)) quasiparticle configurations and the negative parity bands are from vh_(11/2) orbital.

关键词： bands parity

WAPN:a distributed wormhole attack detection approach for wireless sensor networks

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Journal of Zhejiang University-Science A(Applied physics & Engineering) 2009年第2期10卷 279-289页

作者： Fan-rui KONG Chun-wen LI Qing-qing DING Guang-zhao CUI Bing-yi CUI Department of Automation. Tsinghua University Beijing 100084. China State Key Lab of Power Systems Departmet of Electrical Engineering Tsinghua University Beijing 100084 China State Key Lab of Informational Electric Apparatus in Henan Zhengzhou 450002 China Department of Phvsics Nanjing University Nanjing 210093 China

As the applications of wireless sensor networks(WSNs) diversify,providing secure communication is emerging as a critical requirement. In this paper,we investigate the detection of wormhole attack,a serious security issue for WSNs. Wormhole attack is difficult to detect and prevent,as it can work without compromising sensor nodes or breaching the encryption key. We present a wormhole attack detection approach based on the probability distribution of the neighboring-node-number,WAPN,which helps the sensor nodes to judge distributively whether a wormhole attack is taking place and whether they are in the in-fluencing area of the attack. WAPN can be easily implemented in resource-constrained WSNs without any additional requirements,such as node localization,tight synchronization,or directional antennas. WAPN uses the neighboring-node-number as the judging criterion,since a wormhole usually results in a significant increase of the neighboring-node-number due to the extra attacking link. Firstly,we model the distribution of the neighboring-node-number in the form of a Bernoulli distribution. Then the model is simplified to meet the sensor nodes' constraints in computing and memory capacity. Finally,we propose a simple method to obtain the threshold number,which is used to detect the existence of a wormhole. Simulation results show that WAPN is effective under the conditions of different network topologies and wormhole parameters.

关键词：无线个域网无线传感器网络虫洞攻击检测安全防护

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