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Light slowing and all-optical time division multiplexing of hybrid four-wave mixing signal in nitrogen-vacancy center

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Chinese Physics B 2020年第5期29卷 254-259页

作者： Ruimin Wang irfan ahmed Faizan Raza Changbiao Li Yanpeng Zhang School of Science&Key Laboratory for Physical Electronics and Devices of the Ministry of Education&Shaanxi Key Laboratory of Information Photonic Technique Xi’an Jiaotong UniversityXi’an 710049China Department of Physics City University of Hong KongKowloonHong Kong SARChina Electrical Engineering Department Sukkur IBA University65200SindhPakistan

We report the experimental results of hybrid four-wave mixing and fluorescence signals from nitrogen-vacancy(NV)centers in diamond. The fluorescence signals are slowed owing to dark state. The observed delay time of light slowing due to interconversion between NV^- and NV^0 is about 6.4 μs. The relative intensities of read-out signals change with the wavelength and power of writing pulse. Based on light slowing, we present the model of all-optical time division multiplexing. The intensity ratio in different demultiplexed channels is modulated by the wavelength and power of control field. It has potential applications in quantum communication and all-optical network.

关键词： nonlinear optics fluorescence time division multiplexing

There is plenty of room at the top:generation of hot charge carriers and their applications in perovskite and other semiconductor-based optoelectronic devices

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Light(Science & Applications) 2021年第9期10卷 1630-1657页

作者： irfan ahmed Lei Shi Hannu Pasanen Paola Vivo Partha Maity Mohammad Hatamvand Yiqiang Zhan State Key Laboratory of ASIC and System Centre of Micro-Nano SystemSISTFudan University200433ShanghaiChina Department of Physics Government Postgraduate College(Higher Education Department-HED)Khyber Pakhtunkhwa21300MansehraPakistan State Key Laboratory of Surface Physics Key Laboratory of Micro-and Nano-PhotonicsFudan University200433ShanghaiChina Faculty of Engineering and Natural Sciences Tampere UniversityFI-33014TampereFinland KAUST Solar Center Division of Physical Science and EngineeringKing Abdullah University of Science and Technology(KAUST)Thuwal23955-6900RiyadhKingdom of Saudi Arabia

Hot charge carriers(HC)are photoexcited electrons and holes that exist in nonequilibrium high-energy states of photoactive *** cooling time and rapid extraction are the current challenges for the development of future innovative HC-based optoelectronic devices,such as HC solar cells(HCSCs),hot energy transistors(HETs),HC photocatalytic reactors,and lasing *** on a thorough analysis of the basic mechanisms of HC generation,thermalization,and cooling dynamics,this review outlines the various possible strategies to delay the HC cooling as well as to speed up their *** materials with slow cooling behavior,including perovskites and other semiconductors,are thoroughly *** addition,the opportunities for the generation of plasmon-induced HC through surface plasmon resonance and their technological applications in hybrid nanostructures are discussed in *** judiciously designing the plasmonic nanostructures,the light coupling into the photoactive layer and its optical absorption can be greatly enhanced as well as the successful conversion of incident photons to HC with tunable energies can also be ***,the future outlook of HC in optoelectronics is highlighted which will provide great insight to the research community.

关键词： optoelectronic charge plenty

Performance analysis of a random ARQ initialized cooperative communication protocol in shadowed Nakagami-m wireless channel

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Science in China(Series F) 2009年第6期52卷 1027-1036页

作者： ahmed irfan PENG MuGen WANG WenBo SHAH Syed Ismail Wireless Signal Processing and Network Laboratory Beijing University of Posts and Telecommunications Real-Time MIMO Test-Bed Laboratory Iqra University Islamabad Pakistan

In this paper, we develop and analyze an energy efficient ARQ （automatic repeat request） initialized transmit diversity protocol for cooperative *** access control （MAC） layer packet retransmission limit （similar to aShortRetryLimit or aLongRetryLimit [802.11-1997]） has been used as an actuator for transmit cooperative diversity *** take the channel state information （CSI） as a function of retransmission tries and the number of retransmission tries is modeled as a random *** close to the source node are chosen for the transmit *** form expressions are obtained for symbol error rate （SER）, outage capacity and outage probability for the proposed scheme in shadowed fading *** cooperative scheme achieves lower signal-to-noise ratio （SNR）, stumpy outage probability, higher bandwidth, and transmit energy efficiencies for desired average symbol error rate （ASER） than the preceding ARQ based cooperative ***, the results of computer simulations are included to demonstrate the efficacy of the proposed scheme and to verify the accuracy of the analytical expressions.

关键词： automatic repeat request (ARQ) cooperative transmit diversity composite shadowed fading channel wireless networks

Current practice of anticoagulant in the treatment of splanchnic vein thrombosis secondary to acute pancreatitis

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Hepatobiliary & Pancreatic Diseases International 2020年第2期19卷 116-121页

作者： William Norton Gabija Lazaraviciute George Ramsay Irene Kreis irfan ahmed Mohamed Bekheit Department of General Surgery Aberdeen Royal InfirmaryAberdeen AB252ZNUK Rowett Institute of Nutrition and Health University of AberdeenForesterhillAberdeen AB252ZDUK Clinical Effectiveness Unit Royal College of Surgeons of England35-43 Lincoln’s Inn FieldsHolbornLondon WC2A 3PEUK Department of Surgery El Kabbary HospitalEl KabbaryAlexandriaEgypt

Background:Severe acute pancreatitis is a common diagnosis in emergency general surgery and can be a cause of significant morbidity and mortality.A consequence of severe acute pancreatitis is thrombus in the splanchnic *** thrombi can potentially lead to bowel ischemia or hepatic ***,another complication of severe acute pancreatitis is retroperitoneal *** this time,it is unclear if treating patients for splanchnic vein thrombosis in the context of severe acute pancreatitis is associated with any outcome benefit.A systematic review might clarify this *** sources:A two-fold search strategy(one broad and one precise)looked at all published *** review was registered on PROSPERO(ID:CRD42018102705).MEDLINE,EMBASE,PubMed,Cochrane and Web of Science databases were searched and potentially relevant papers were reviewed indepen-dently by two *** disagreement was reviewed by a third independent *** outcome was reestablishment of flow in the thrombosed vein versus bleeding ***:Of 1462 papers assessed,a total of 16 papers were eligible for *** were no ran-domized controlled trials,2 were case series,5 retrospective single-center studies and 9 case *** were a total of 198 patients in these studies of whom 92(46.5%)received anticoagulation *** rates of recanalization of veins in the treated and non-treated groups was 14%and 11%and bleeding complications were 16%and 5%,***,the included studies were too heterogeneous to undertake a ***:The systematic review highlights the lack evidence addressing this clinical ***-fore a randomized controlled trial would be appropriate to undertake.

关键词： Severe acute pancreatitis Splanchnic vein thrombosis Anticoagulant therapy

Cartesian Product Based Transfer Learning Implementation for Brain Tumor Classification

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Computers, Materials & Continua 2022年第11期73卷 4369-4392页

作者： irfan ahmed Usmani Muhammad Tahir Qadri Razia Zia Asif Aziz Farheen Saeed Electronic Engineering Department Sir Syed University of Engineering&TechnologyKarachi75300Pakistan Department of Computer Science Bahria University Karachi CampusKarachi75260Pakistan Christus Trinity Clinic TexasUSA

Knowledge-based transfer learning techniques have shown good performance for brain tumor classification,especially with small ***,to obtain an optimized model for targeted brain tumor classification,it is challenging to select a pre-trained deep learning(DL)model,optimal values of hyperparameters,and optimization algorithm(solver).This paper first presents a brief review of recent literature related to brain tumor ***,a robust framework for implementing the transfer learning technique is *** the proposed framework,a Cartesian product matrix is generated to determine the optimal values of the two important hyperparameters:batch size and learning *** extensive exercise consisting of 435 simulations for 11 state-of-the-art pre-trained DL models was performed using 16 paired hyperparameters from the Cartesian product matrix to input the model with the three most popular solvers(stochastic gradient descent with momentum(SGDM),adaptive moment estimation(ADAM),and root mean squared propagation(RMSProp)).The 16 pairs were formed using individual hyperparameter values taken from literature,which generally addressed only one hyperparameter for optimization,rather than making a grid for a particular *** proposed framework was assessed using a multi-class publicly available dataset consisting of glioma,meningioma,and pituitary *** assessment shows that ResNet18 outperforms all other models in terms of accuracy,precision,specificity,and recall(sensitivity).The results are also compared with existing state-of-the-art research work that used the same *** comparison was mainly based on performance metric“accuracy”with support of three other parameters“precision,”“recall,”and“specificity.”The comparison shows that the transfer learning technique,implemented through our proposed framework for brain tumor classification,outperformed all existing *** the best of our knowledge,the proposed framework is a

关键词： Deep transfer learning Cartesian product hyperparameter optimization magnetic resonance imaging(MRI) brain tumor classification

Field evaluation of some bait additives against Indian crested porcupine(Hystrix indica)(Rodentia:Hystricidae)

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Integrative Zoology 2013年第3期8卷 285-292页

作者： Muhammad MUSHTAQ Iftikhar HUSSAIN Afsar MIAN Shahid MUNIR irfan ahmed Abdul Aziz KHAN Department of Zoology PMAS Arid Agriculture UniversityRawalpindiPakistan Wildlife Management PMAS Arid Agriculture UniversityRawalpindiPakistan National Agricultural Research Centre IslamabadPakistan

This research study evaluated the effect of different additives on the bait consumption by Indian crested porcupine,a serious forest and agricultural pest,under field *** additives(saccharin,common salt,bone meal,fish meal,peanut butter,egg yolk,egg shell powder,yeast powder,mineral oil and coconut oil)at 2 and 5%each were tested for their relative preference,using groundnut-maize(1:1)as basic *** the additives were tested under a no-choice test *** control tests,no additive was mixed with the basic *** at 5%concentration significantly enhanced the consumption of bait over the basic bait,while 2%saccharin supplemented bait resulted in a non-significant bait *** other additives did not enhance the consumption of the bait material;rather,these worked as ***,the repellency was lowest with the common salt,followed by egg yolk,egg shell powder,bone meal,peanut butter,mineral oil,fish meal and yeast powder,while coconut remained the most repellent *** present study suggested that groundnut-maize(1:1)supplemented with 5%saccharin was the preferred bait combination,and can be used with different rodenticides for the management of Indian crested porcupine.

关键词： additives baits evaluation Hystrix indica Indian crested porcupine

The role of graft reperfusion sequence in the development of non-anastomotic biliary strictures following orthotopic liver transplantation: A meta-analysis

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Hepatobiliary & Pancreatic Diseases International 2019年第1期18卷 4-11页

作者： Mohamed Bekheit Matteo Catanzano Stuart Shand irfan ahmed ELSaid ELKayal Gihan Mohamed Shehata Adel Zaki Center of Liver Surgery and Transplantation Paul Brousse Hospital University of Paris-Sud Medical Research Institute University of Alexandria HPB Surgery Unit Department of Surgery Aberdeen Royal Infirmary Department of Surgery Elkabbary General Hospital University of Aberdeen Department of Surgery Alexandria Main University Hospital Faculty of Medicine

Background: Liver transplant is a potential cure for liver failure and hepatic malignancy but there are many techniques which have been described for vascular reconstruction. This study was to compare the prevalence of non-anastomotic biliary stricture and other surgical complications based on Clavien-Dindo scoring system, in initial portal reperfusion(sequential) versus simultaneous or initial artery reperfusion. Data sources: Meta-analysis of published studies comparing the outcomes of both techniques was carried out. Data search was conducted across the major databases and studies were selected under the guidance of the Cochrane guidelines for systematic reviews and meta-analysis. Results: Seven studies were included to address the primary and the secondary outcomes. No statistical difference was found in the incidence of non-anastomotic biliary strictures(OR = 0.40; P = 0.14), regardless of reperfusion technique. The pooled estimate of the Clavien-Dindo grading of complications was not significantly different between the techniques, though Clavien-Dindo II complications were higher in the simultaneous or initial artery reperfusion group than the initial portal reperfusion group(OR = 2.73; P = 0.01). Similarly, there was no difference in the operative time, hospital stay and other outcomes addressed in this report. Conclusions: The available evidence suggests that there is no significant difference demonstrated in the rate of non-anastomotic biliary strictures or other complications, between the two techniques, except for Clavien-Dindo II complications.

关键词： Liver transplantation Organ transplantation Liver surgery Rejection

Data-driven design of high-performance MASnxPb1-xI3 perovskite materials by machine learning and experimental realization

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Light(Science & Applications) 2022年第9期11卷 2115-2126页

作者： XIA CAI FENGCAI LIU ANRAN YU JIAJUN QIN MOHAMMAD HATAMVAND irfan ahmed JIAYAN LUO YIMING ZHANG HAO ZHANG YIQIANG ZHAN School of Information Science and Technology Fudan UniversityShanghai 200433China College of Information Mechanical and Electrical EngineeringShanghai Normal UniversityShanghai 200234China Center of Micro-Nano System Fudan UniversityShanghai 200433China Department of Physics Chemistry and BiologyLinkoping UniversityLinkoping SE-58183Sweden Key Laboratory of Micro and Nano Photonic Structures and Department of Optical Science and Engineering Fudan UniversityShanghai 200433China Yiwu Research Institute of Fudan University Chengbei RoadYiwu CityZhejiang 322000China

The photovoltaic performance of perovskite solar cell is determined by multiple interrelated factors,such as perovskite compositions,electronic properties of each transport layer and fabrication parameters,which makes it rather challenging for optimization of device performances and discovery of underlying ***,we propose and realize a novel machine learning approach based on forward-reverse framework to establish the relationship between key parameters and photovoltaic performance in high-profile MASnxPb1-xI3 perovskite *** proposed method establishes the asymmetrically bowing relationship between band gap and Sn composition,which is precisely verified by our *** on the analysis of structural evolution and SHAP library,the rapid-change region and low-bandgap plateau region for small and large Sn composition are explained,*** establishing the models for photovoltaic parameters of working photovoltaic devices,the deviation of short-circuit current and open-circuit voltage with band gap in defective-zone and low-bandgap-plateau regions from Shockley-Queisser theory is captured by our models,and the former is due to the deep-level traps formed by crystallographic distortion and the latter is due to the enhanced susceptibility by increased Sn4+*** more difficulty for hole extraction than electron is also concluded in the models and the prediction curve of power conversion efficiency is in a good agreement with Shockley-Queisser *** the help of search and optimization algorithms,an optimized Sn:Pb composition ratio near 0.6 is finally obtained for high-performance perovskite solar cells,then verified by our *** constructive method could also be applicable to other material optimization and efficient device development.

关键词： perovskite performance optimization

Forecasting investment and consumption behavior of economic agents through dynamic computable general equilibrium model

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Financial Innovation 2018年第1期4卷 125-145页

作者： irfan ahmed Claudio Socci Francesca Severini Qaiser Rafique Yasser Rosita Pretaroli Preston University No.85Street 3Sector H-8/1MacerataPakistan University of Macerata MacerataItaly.

Much research has been devoted to examination of the financial easing policy of the European Central Bank(ECB).However,this study is one of the first to use a dynamic micro-founded model to investigate empirically the impact of the ECB’s Quantitative Easing(QE)policy on consumption and investment by economic agents in Italy(households,government,firms,and the rest of the world).For this purpose,we constructed a Financial Social Accounting Matrix(FSAM)for the Italian economy for the year 2009 to calibrate a dynamic computable general equilibrium model(DCGE).This model allowed us to evaluate the direct and indirect impact of money flow on the behavior of consumption and *** findings of the study confirmed the positive impact of the ECB’s monetary policy on the level of investment and consumption.

关键词： European Central Bank Quantitative easing Monetary policy Investment behavior Social accounting matrix Dynamic CGE analysis