Ports play a fundamental role in a sustainable integration of Africa in International trade. Both importers and exporters, shipping companies and government, however face high cost for sea transport and substantial in...Ports play a fundamental role in a sustainable integration of Africa in International trade. Both importers and exporters, shipping companies and government, however face high cost for sea transport and substantial inefficiency in port operations. This has resulted in congestion, higher dwell time, higher costs which affect the competitive ability in sub regional and global economy. This study investigates the main factors explaining poor container handling operations and limited competitive ability in Cameroonian Ports and aggregating this to the competitive position of Cameroonian ports in the West and Central African sub-regions (WCA). Using Analytic Hierarchy Process (A.H.P), the paper seeks to provide a basic understanding of container transportation and port’s terminal operations problems (constraints & ineffectiveness) in Cameroon.展开更多
Decentralized finance(DeFi)is a general term for a series of financial products and services.It is based on blockchain technology and has attracted people’s attention because of its open,transparent,and intermediary ...Decentralized finance(DeFi)is a general term for a series of financial products and services.It is based on blockchain technology and has attracted people’s attention because of its open,transparent,and intermediary free.Among them,the DeFi ecosystem based on Ethereum-based blockchains attracts the most attention.However,the current decentralized financial system built on the Ethereum architecture has been exposed to many smart contract vulnerabilities during the last few years.Herein,we believe it is time to improve the understanding of the prevailing Ethereum-based DeFi ecosystem security issues.To that end,we investigate the Ethereum-based DeFi security issues:1)inherited from the real-world financial system,which can be solved by macro-control;2)induced by the problems of blockchain architecture,which require a better blockchain platform;3)caused by DeFi invented applications,which should be focused on during the project development.Based on that,we further discuss the current solutions and potential directions ofDeFi security.According to our research,we could provide a comprehensive vision to the research community for the improvement of Ethereum-basedDeFi ecosystem security.展开更多
BACKGROUND:Automated external defibrillators(AEDs)enable laypeople to provide early defi brillations to patients undergoing cardiac arrest,but scant information is available on the general public’s ability to use AED...BACKGROUND:Automated external defibrillators(AEDs)enable laypeople to provide early defi brillations to patients undergoing cardiac arrest,but scant information is available on the general public’s ability to use AEDs.This study assessed the ability of laypeople to operate AEDs,the effect of a 15-minute training,and whether skills differed by age.METHODS:From May 1 to December 31,2018,a prospective simulation study was conducted with 94 laypeople aged 18–65 years(32 aged 18–24 years,34 aged 25–54 years,and 28 aged 55–65 years)with no prior AED training.The participants’AED skills were assessed individually pretraining,post-training,and at a three-month follow-up using a simulated cardiac arrest scenario.The critical actions and time intervals were evaluated during the AED operating process.RESULTS:Only 14(14.9%)participants(eight aged 18–24 years,four aged 25–54 years,and two aged 55–65 years)successfully delivered defi brillations before training.AED operation errors were more likely to occur among the participants aged 55–65 years than among other age groups.After training,the proportion of successful defi brillations increased signifi cantly(18–24 years old:25.0%vs.71.9%,P<0.01;25–54 years old:11.8%vs.70.6%,P<0.01;55–65 years old:7.1%vs.67.9%,P<0.01).After three months,26.1%of the participants aged 55–65 years successfully delivered defi brillations,which was signifi cantly lower than that of participants aged 18–24 years(54.8%)and 25–54 years(64.3%)(P=0.02).There were no differences in time measures among three age groups in each test.CONCLUSIONS:The majority of untrained laypeople cannot effectively operate AEDs.More frequent training and refresher courses are crucial to improve AED skills.展开更多
Celiac disease(CD) is now recognized as a common disorder among Middle Eastern(ME) and North African(NA) populations.The aim of this review is to assess the available data regarding CD in the ME and NA and to compare ...Celiac disease(CD) is now recognized as a common disorder among Middle Eastern(ME) and North African(NA) populations.The aim of this review is to assess the available data regarding CD in the ME and NA and to compare this information with that of Western countries.A literature review was performed using the electronic databases PubMed and Medline(1950-2008) as search engines,and "celiac disease" was used as a Mesh term.The search was limited to ME and NA countries.The prevalence of CD in ME and NA countries among low risk populations is similar to that of Western countries,but is higher in high risk populations such as those with type 1 diabetes.It is underestimated because of lack of clinical suspicion and lack of patient awareness.Clinical presentations in term of gastrointestinal,hematologic,skeletal,and liver manifestations are similar between both populations except for a high prevalence of short stature in some ME and NA countries.Few studies have addressed atypical or silent CD.As in the West,diagnosis is initially made by serological tests and is confirmed by small intestinal biopsies.Gluten-free diet is the main mode of treatment with a higher apparent adherence rate than in the West.Most disease complications result from malabsorption.The disease is strongly associated with HLA DQ2 and to a lesser extent with HLA DQ8 alleles.In conclusion,CD prevalence is underestimated,with little data available about its malignant complications.Disease parameters in the ME and NA are otherwise similar to those in Western countries.展开更多
Recent advancements in decentralized finance(DeFi)have resulted in a rapid increase in the use of Automated Market Makers(AMMs)for creating decentralized exchanges(DEXs).In this paper,we organize these developments by...Recent advancements in decentralized finance(DeFi)have resulted in a rapid increase in the use of Automated Market Makers(AMMs)for creating decentralized exchanges(DEXs).In this paper,we organize these developments by treating an AMM as a neoclassical black-box characterized by the conversion of inputs(tokens)to outputs(prices).The conversion is governed by the technology of the AMM summarized by an‘exchange function’.Various types of AMMs are examined,including:Constant Product Market Makers;Constant Mean Market Makers;Constant Sum Market Makers;Hybrid Function Market Makers;and,Dynamic Automated Market Makers.The paper also looks at the impact of introducing concentrated liquidity in an AMM.Overall,the framework presented here provides an intuitive geometric representation of how an AMM operates,and a clear delineation of the similarities and differences across the various types of AMMs.展开更多
BACKGROUND: To popularize the wide-spread use of automated external defi brillator(AED) to save life in sudden cardiac arrest, we compared the strength and weakness of different types of AEDs to enable a sound selecti...BACKGROUND: To popularize the wide-spread use of automated external defi brillator(AED) to save life in sudden cardiac arrest, we compared the strength and weakness of different types of AEDs to enable a sound selection based on regional requirement.METHODS: This was a retrospective descriptive study. Different types of AEDs were compared according to the information of AEDs from manuals and brochures provided by the manufacturers. Fifteen types of AEDs were divided into 3 groups, basic, intermediate and advanced.RESULTS: Lifeline? AUTO AED had the best performance in price, portability and user-friendly among AEDs of basic level. It required less time for shock charging. Samaritan PAD defi brillator was superior in price, portability, durability and characteristic among AEDs of intermediate level. It had the longest warranty and highest protection against water and dust. Lifeline? PRO AED had the best performance in most of the criteria among AEDs of advanced level and offered CPR video and manual mode for laypersons and clinicians respectively.CONCLUSION: Lifeline? AUTO AED, Samaritan PAD def ibrillator, Lifeline? PRO AED are superior in AEDs of basic, intermediate and advanced levels, respectively. A feasible AED may be chosen by users according to the regional requirement and the current information about the best available products.展开更多
ON August 15, 2002, world famousescapologist Robert Gallup gave a free performance at the foot of the Badaling Great Wall. It was for the benefit of young people from China’s western regions who cannot afford to cont...ON August 15, 2002, world famousescapologist Robert Gallup gave a free performance at the foot of the Badaling Great Wall. It was for the benefit of young people from China’s western regions who cannot afford to continue their education."Defying death" is Gallup’s specialty. With the help of an assistant, he is tied up, and sus-展开更多
CHINESE consumers are caught up in a power play - quite lit- erally. When it comes to selecting an electricity supplier, choic- es are limited to the State Grid Corp. in the north and China Southern Power Grid in the ...CHINESE consumers are caught up in a power play - quite lit- erally. When it comes to selecting an electricity supplier, choic- es are limited to the State Grid Corp. in the north and China Southern Power Grid in the south. Monopoly of the industry has long been the status quo in China, but now there are signs that the situation is changing.展开更多
Nowadays,tungsten oxides,as a typical transition metal oxide,are widely and intensively investigated owing to their excellent material properties and device properties.Controlling oxygen defi ciency in tungsten oxides...Nowadays,tungsten oxides,as a typical transition metal oxide,are widely and intensively investigated owing to their excellent material properties and device properties.Controlling oxygen defi ciency in tungsten oxides is typically the key to enhance their performances for a variety of critical technological applications.With a gradual increase of oxygen defi ciency,various non-stoichiometric tungsten oxides can be formed by re-adjustment of the atomic arrangement,which exhibits superior performances than their traditional stoichiometric counterparts.This review mainly focuses on the recent advances in oxygen-defi cient tungsten oxides from the point of atomic structures,including the forming mechanism of non-stoichiometric tungsten oxides and the superiority of these oxygen-defi cient tungsten oxides in energy-related devices.Finally,the challenge and perspective of oxygen-defi cient tungsten oxides are also discussed.展开更多
Doppler global velocimetry （DGV） has already been shown to be an interesting technique capable of measuring the three components of velocity in a plane. A 1-component DGV system is currently under development at the...Doppler global velocimetry （DGV） has already been shown to be an interesting technique capable of measuring the three components of velocity in a plane. A 1-component DGV system is currently under development at the LMFA, using a stabilized continuous wave （CW） argon ion laser for ermssion, lne receiver Ieatures only one camera for both signal and reference images and incorporates a DEF1 system to adjust the incident laser light frequency and its transmission coefficient on the iodine cell absorption line. A description of the whole system is presented and a validation with measurements of axial velocities at several positions in a round free jet is proposed.展开更多
Interest Rate Swap(IRS)is the most vivid application of the principle of comparative advantage in the financial field.The effectiveness of interest rate swap in managing interest rate risk has been widely recognized.H...Interest Rate Swap(IRS)is the most vivid application of the principle of comparative advantage in the financial field.The effectiveness of interest rate swap in managing interest rate risk has been widely recognized.However,the traditional interest rate swap transaction is complicated.Meanwhile,there usually existmarket risks and credit risks.To alleviate risks and cost,and improve liquidity of interest rate swap,this paper proposes a smart contract basedmatching platform for interest rate swap of real fiat currency.Smart contracts play a key role for sharing data among participants,which can not be forged or tampered with.In our design,an efficient peer-to-peer counterparty matching method on the chain is proposed.The whole trading process of interest rate swap is carried out on the blockchain,which has higher security.A prototype based on smart contracts running on Ethereum is implemented and validates our design.展开更多
文摘Ports play a fundamental role in a sustainable integration of Africa in International trade. Both importers and exporters, shipping companies and government, however face high cost for sea transport and substantial inefficiency in port operations. This has resulted in congestion, higher dwell time, higher costs which affect the competitive ability in sub regional and global economy. This study investigates the main factors explaining poor container handling operations and limited competitive ability in Cameroonian Ports and aggregating this to the competitive position of Cameroonian ports in the West and Central African sub-regions (WCA). Using Analytic Hierarchy Process (A.H.P), the paper seeks to provide a basic understanding of container transportation and port’s terminal operations problems (constraints & ineffectiveness) in Cameroon.
基金supported by the Key-Area Research and Development Program of Guangdong Province 2020B0101090003CCF-NSFOCUS Kunpeng Scientific Research Fund (CCFNSFOCUS 2021010)+4 种基金Innovation Fund Program of the Engineering Research Center for Integration and Application of Digital Learning Technology of Ministry of Education under Grant No.1221027National Natural Science Foundation of China (Grant Nos.61902083,62172115,61976064)Guangdong Higher Education Innovation Group 2020KCXTD007 and Guangzhou Higher Education Innovation Group (No.202032854)Guangzhou Fundamental Research Plan of“Municipal-School”Jointly Funded Projects (No.202102010445)Guangdong Province Science and Technology Planning Project (No.2020A1414010370).
文摘Decentralized finance(DeFi)is a general term for a series of financial products and services.It is based on blockchain technology and has attracted people’s attention because of its open,transparent,and intermediary free.Among them,the DeFi ecosystem based on Ethereum-based blockchains attracts the most attention.However,the current decentralized financial system built on the Ethereum architecture has been exposed to many smart contract vulnerabilities during the last few years.Herein,we believe it is time to improve the understanding of the prevailing Ethereum-based DeFi ecosystem security issues.To that end,we investigate the Ethereum-based DeFi security issues:1)inherited from the real-world financial system,which can be solved by macro-control;2)induced by the problems of blockchain architecture,which require a better blockchain platform;3)caused by DeFi invented applications,which should be focused on during the project development.Based on that,we further discuss the current solutions and potential directions ofDeFi security.According to our research,we could provide a comprehensive vision to the research community for the improvement of Ethereum-basedDeFi ecosystem security.
基金the National Natural Science Foundation of China(81703303)Shanghai Municipal Government Pujiang Research Development Program(17PJC070)+1 种基金HeartRescue Project China Programand Innovative Research Team of High-level Local Universities in Shanghai.
文摘BACKGROUND:Automated external defibrillators(AEDs)enable laypeople to provide early defi brillations to patients undergoing cardiac arrest,but scant information is available on the general public’s ability to use AEDs.This study assessed the ability of laypeople to operate AEDs,the effect of a 15-minute training,and whether skills differed by age.METHODS:From May 1 to December 31,2018,a prospective simulation study was conducted with 94 laypeople aged 18–65 years(32 aged 18–24 years,34 aged 25–54 years,and 28 aged 55–65 years)with no prior AED training.The participants’AED skills were assessed individually pretraining,post-training,and at a three-month follow-up using a simulated cardiac arrest scenario.The critical actions and time intervals were evaluated during the AED operating process.RESULTS:Only 14(14.9%)participants(eight aged 18–24 years,four aged 25–54 years,and two aged 55–65 years)successfully delivered defi brillations before training.AED operation errors were more likely to occur among the participants aged 55–65 years than among other age groups.After training,the proportion of successful defi brillations increased signifi cantly(18–24 years old:25.0%vs.71.9%,P<0.01;25–54 years old:11.8%vs.70.6%,P<0.01;55–65 years old:7.1%vs.67.9%,P<0.01).After three months,26.1%of the participants aged 55–65 years successfully delivered defi brillations,which was signifi cantly lower than that of participants aged 18–24 years(54.8%)and 25–54 years(64.3%)(P=0.02).There were no differences in time measures among three age groups in each test.CONCLUSIONS:The majority of untrained laypeople cannot effectively operate AEDs.More frequent training and refresher courses are crucial to improve AED skills.
文摘Celiac disease(CD) is now recognized as a common disorder among Middle Eastern(ME) and North African(NA) populations.The aim of this review is to assess the available data regarding CD in the ME and NA and to compare this information with that of Western countries.A literature review was performed using the electronic databases PubMed and Medline(1950-2008) as search engines,and "celiac disease" was used as a Mesh term.The search was limited to ME and NA countries.The prevalence of CD in ME and NA countries among low risk populations is similar to that of Western countries,but is higher in high risk populations such as those with type 1 diabetes.It is underestimated because of lack of clinical suspicion and lack of patient awareness.Clinical presentations in term of gastrointestinal,hematologic,skeletal,and liver manifestations are similar between both populations except for a high prevalence of short stature in some ME and NA countries.Few studies have addressed atypical or silent CD.As in the West,diagnosis is initially made by serological tests and is confirmed by small intestinal biopsies.Gluten-free diet is the main mode of treatment with a higher apparent adherence rate than in the West.Most disease complications result from malabsorption.The disease is strongly associated with HLA DQ2 and to a lesser extent with HLA DQ8 alleles.In conclusion,CD prevalence is underestimated,with little data available about its malignant complications.Disease parameters in the ME and NA are otherwise similar to those in Western countries.
文摘Recent advancements in decentralized finance(DeFi)have resulted in a rapid increase in the use of Automated Market Makers(AMMs)for creating decentralized exchanges(DEXs).In this paper,we organize these developments by treating an AMM as a neoclassical black-box characterized by the conversion of inputs(tokens)to outputs(prices).The conversion is governed by the technology of the AMM summarized by an‘exchange function’.Various types of AMMs are examined,including:Constant Product Market Makers;Constant Mean Market Makers;Constant Sum Market Makers;Hybrid Function Market Makers;and,Dynamic Automated Market Makers.The paper also looks at the impact of introducing concentrated liquidity in an AMM.Overall,the framework presented here provides an intuitive geometric representation of how an AMM operates,and a clear delineation of the similarities and differences across the various types of AMMs.
文摘BACKGROUND: To popularize the wide-spread use of automated external defi brillator(AED) to save life in sudden cardiac arrest, we compared the strength and weakness of different types of AEDs to enable a sound selection based on regional requirement.METHODS: This was a retrospective descriptive study. Different types of AEDs were compared according to the information of AEDs from manuals and brochures provided by the manufacturers. Fifteen types of AEDs were divided into 3 groups, basic, intermediate and advanced.RESULTS: Lifeline? AUTO AED had the best performance in price, portability and user-friendly among AEDs of basic level. It required less time for shock charging. Samaritan PAD defi brillator was superior in price, portability, durability and characteristic among AEDs of intermediate level. It had the longest warranty and highest protection against water and dust. Lifeline? PRO AED had the best performance in most of the criteria among AEDs of advanced level and offered CPR video and manual mode for laypersons and clinicians respectively.CONCLUSION: Lifeline? AUTO AED, Samaritan PAD def ibrillator, Lifeline? PRO AED are superior in AEDs of basic, intermediate and advanced levels, respectively. A feasible AED may be chosen by users according to the regional requirement and the current information about the best available products.
文摘ON August 15, 2002, world famousescapologist Robert Gallup gave a free performance at the foot of the Badaling Great Wall. It was for the benefit of young people from China’s western regions who cannot afford to continue their education."Defying death" is Gallup’s specialty. With the help of an assistant, he is tied up, and sus-
文摘CHINESE consumers are caught up in a power play - quite lit- erally. When it comes to selecting an electricity supplier, choic- es are limited to the State Grid Corp. in the north and China Southern Power Grid in the south. Monopoly of the industry has long been the status quo in China, but now there are signs that the situation is changing.
基金supported by the National Natural Science Foundation of China(No.61904080)the Macao Young Scholars Program of China(No.AM2020005)Guangdong Basic and Applied Basic Research Foundation(No.2022A1515110994).
文摘Nowadays,tungsten oxides,as a typical transition metal oxide,are widely and intensively investigated owing to their excellent material properties and device properties.Controlling oxygen defi ciency in tungsten oxides is typically the key to enhance their performances for a variety of critical technological applications.With a gradual increase of oxygen defi ciency,various non-stoichiometric tungsten oxides can be formed by re-adjustment of the atomic arrangement,which exhibits superior performances than their traditional stoichiometric counterparts.This review mainly focuses on the recent advances in oxygen-defi cient tungsten oxides from the point of atomic structures,including the forming mechanism of non-stoichiometric tungsten oxides and the superiority of these oxygen-defi cient tungsten oxides in energy-related devices.Finally,the challenge and perspective of oxygen-defi cient tungsten oxides are also discussed.
基金the CIRT (Consortium Indus trie Recherche en Turbomachines) which is supporting this workmore particularly at the LMFA, Alain Ef fernelli for building many elements of the receiver, Gil bert Halter for helping in the collimation processAndre Vouillarmet for his advice in this project.
文摘Doppler global velocimetry （DGV） has already been shown to be an interesting technique capable of measuring the three components of velocity in a plane. A 1-component DGV system is currently under development at the LMFA, using a stabilized continuous wave （CW） argon ion laser for ermssion, lne receiver Ieatures only one camera for both signal and reference images and incorporates a DEF1 system to adjust the incident laser light frequency and its transmission coefficient on the iodine cell absorption line. A description of the whole system is presented and a validation with measurements of axial velocities at several positions in a round free jet is proposed.
文摘Interest Rate Swap(IRS)is the most vivid application of the principle of comparative advantage in the financial field.The effectiveness of interest rate swap in managing interest rate risk has been widely recognized.However,the traditional interest rate swap transaction is complicated.Meanwhile,there usually existmarket risks and credit risks.To alleviate risks and cost,and improve liquidity of interest rate swap,this paper proposes a smart contract basedmatching platform for interest rate swap of real fiat currency.Smart contracts play a key role for sharing data among participants,which can not be forged or tampered with.In our design,an efficient peer-to-peer counterparty matching method on the chain is proposed.The whole trading process of interest rate swap is carried out on the blockchain,which has higher security.A prototype based on smart contracts running on Ethereum is implemented and validates our design.
