134 resultados para CBC


Relevância:

10.00% 10.00%

Publicador:

Resumo:

Aircraft emissions of black carbon (BC) contribute to anthropogenic climate forcing and degrade air quality. The smoke number (SN) is the current regulatory measure of aircraft particulate matter emissions and quantifies exhaust plume visibility. Several correlations between SN and the exhaust mass concentration of BC (CBC) have been developed, based on measurements relevant to older aircraft engines. These form the basis of the current standard method used to estimate aircraft BC emissions (First Order Approximation version 3 [FOA3]) for the purposes of environmental impact analyses. In this study, BC with a geometric mean diameter (GMD) of 20, 30, and 60 nm and filter diameters of 19 and 35 mm are used to investigate the effect of particle size and sampling variability on SN measurements. For BC with 20 and 30 nm GMD, corresponding to BC emitted by modern aircraft engines, a smaller SN results from a given CBC than is the case for BC with 60 nm GMD, which is more typical of older engines. An updated correlation between CBC and SNthat accounts for typical size of BC emitted by modern aircraft is proposed. An uncertainty of ±25% accounts for variation in GMD in the range 20-30 nm and for the range of filter diameters. The SN-CBC correlation currently used in FOA3 underestimates by a factor of 2.5-3 for SN <15, implying that current estimates of aircraft BC emissions derived from SN are underestimated by the same factor. Copyright © American Association for Aerosol Research.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

After grass carps Ctenopharyngodon idellus were injected with cortisol, with (CBC) and without (C) a cocoa butter carrier, the effects of both slowly and rapidly acting exogenous cortisol oil their non-specific immune functions were investigated. On the one hand, after injection with CBC, the cortisol concentration and lysozyme activity in fish serum were enhanced and were sustained at high levels for a long period (30 days). The killing activity in the serum declined with time, and phagocytosis of head kidney macrophages diminished significantly (P < 0.05 or P < 0.01). The leukocrit values in the high dose group (31-8 mg cortisol fish(-1)) increased over time, however, with the maximum average being 5.6% at day 30. The spleen mass index in the high dose group was 0.93 x 10(-3) after 30 days, notably lower (P < 0.05) than that in the control group. In addition, a decrease in resistance to Aeronionas hydrophilo infection in cortisol-treated fish was shown, with the final cumulative mortalities being 54.5 and 66.7% in the low and high dose groups, respectively. On the other hand, there was a decrease in both serum cortisol concentration and lysozyme activity of the experimental fish within 2 weeks after injection with C, where plasma bactericidal activities in the high dose group (31-8 mg cortisol fish(-1)) were remarkably lower (P < 0.01) than those in the control group at each sampling, but were increased slightly over time. The results of which were different from those in the CBC trial. Phagocytic activity of head kidney macrophages and spleen mass index decreased significantly (P < 0.05), while there were increases in leukocrit value and cumulative mortality due to A. hydrophila. The results of which were similar to those in the CBC trial. This study indicated that the injection of cortisol depressed the non-specific immune functions of the grass carp and increased its susceptibility to disease. (c) 2005 The Fisheries Society of the British Isles.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Submitted by zhangdi (zhangdi@red.semi.ac.cn) on 2009-04-13T11:45:31Z

Relevância:

10.00% 10.00%

Publicador:

Resumo:

分组密码工作模式是利用分组密码解决实际问题的密码方案.好的工作模式可以弥补分组密码的某些缺憾;相反,不好的工作模式可能带来安全隐患.工作模式的研究始终伴随着分组密码的研究历史,新的分组密码标准的推出,都会伴随着相应工作模式的研究.从针对DES的ECB、CBC、CFB和OFB,到针对AES的CTR、CCM、CMAC、GCM和AESKW,作者以各种模式标准为主线,介绍分组密码工作模式的设计理念、安全模型、二十多年的研究成果以及发展现状.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

在随机Oracle模型的基础上, 提出一种基于单向陷门置换(trapdoor permutations, TDPs)的、可并行的、长消息签密方案——PLSC (parallel long-message signcryption). 该方法采用“整体搅乱, 局部加密(scramble all, and encrypt small)”的思想, 用一个伪随机数对要传送的消息和用户的身份(ID)进行“搅乱(scrambling operation)”, 然后对两个固定长度的小片段(并行地)进行单向陷门置换(TDP)操作. 这种设计使得整个方案可直接高效地处理任意长度的消息, 既可避免循环调用单向陷门置换(如CBC模式)所造成的计算资源的极度消耗, 也可避免由“对称加密方案”与“签密方案”进行“黑盒混合(black-box hybrid)”所造成的填充(padding)冗余. 不仅可以显著地节约消息带宽, 而且可以显著地提高整体效率. 具体地说, 该方法对任何长度的消息进行签密, 仅需进行一次接收方的TDP运算(相当于加密), 以及一次发送方的TDP运算(相当于签名), 从而最大限度地降低了TDP运算的次数, 提高了整体的运算效率. 因为, 对于公钥加密算法来说, 运算量主要集中在TDP运算上, TDP运算是整个算法的瓶颈所在. 另一方面, 由于避免了填充上的冗余, 新方案的效率也高于标准的“黑盒混合”方案.重要的是, 新方案能够达到选择密文攻击下的紧致的语义安全性(IND- CCA2)、密文完整性(INT-CTXT)以及不可否认性(non-repudiation). 而且所有这些安全要求都可以在多用户(multi-user)、内部安全(insider-security)的环境下得以实现. 另外, 尽管新方案主要针对长消息的签密, 但它也可应用于某些不能进行大块数据处理的环境(智能卡或其他只有少量内存的环境). 也就是说, 对于这些小内存设备来说, 仍然可以用该方案来实现长消息的签密处理.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

本论文对流动注射在分光光度法中的应用进行了研究。结合流动注射分析的基本特点,建立了药品中抗坏血酸、稀土铝合金中的稀土总量的快速测定方法;采用RE-(CDBC-CPA)、Ba-(DBC-CPA)、和Ge-SAF-CTMAB三体系,探索了流动注射分光光度法在提高测定选择性上的可能性;可用交替注入法同时测定了矿石中的铁和钛;基于Gd、y的速差动力学差异测定了二者混合稀土中的单一稀土。1.“铁(Ⅲ)-邻菲啰啉溶液体系流动注射分光光度法测定药品中的抗坏血酸“一部分,基于抗坏血酸对高铁定量还原成亚铁后与邻菲啰啉显色,试验了流路参数及显色条件对反应的影响,建立了片剂、注射剂中抗坏血酸的快速测定方法。本方法体系简单,操作快速、方便。“反相流动注射分光光度法测定稀土铝合金中的稀土总量”一部分,基于稀土与DBC-CPA的快速显色反应,确定了适宜的流路参数及显色条伯,在此条件下,可能只需一种混合稀土标液就可对不同配份的样品进行分析,从而简化了手续,样品测定结果满意。2.“反相流动注射分析光度法测定的选择性”一部分,采用R_E-(CBC-CPA)、Ba-(DBC-CPA)、和Ge-SAF-CTMAB三体系对流动注射分光光度法提高测定选择性进行了试验。实验结果表明,选取适宜的条件,可以抑制干扰。对于待测组分反应快而干扰组分反应慢的体系,采用少量低浓度的显色剂,可降低干扰组分的干扰程度。本文中,在选定的条件下,三体系的选择性均有不同程度的提高。3.“交替注入流动注射分光光度法同时测定岩矿中的全铁和钛”一部分,以钛铁试剂为显色剂,抗坏血酸为预还原剂,采用交替注入的方法,快速测定了岩矿中的全铁和钛,样品分析结果满意;“流动注射速差动力学分光光度法同时测定Gd、y混合稀土中的单一稀土“一部分,基于Gd、y的三氯偶氮胂配合物在CyDTA存在下褪色速率的不同,选 用同一长度不同内径的反应线圈,试验了流路参数及显色条件对二者配合物褪色速率的影响,推导了计算二者各自含量的公式,对于不同配比(1:8到8:1,以氧化物计)的Gd、y混合样品,测定结果较为满意,回收率在90-110%之间。

Relevância:

10.00% 10.00%

Publicador:

Resumo:

在信息安全的许多实际应用中往往需要同时提供私密性和认证性,通常采用加密模式和消息认证码的组合来实现这一目的,但这种实现方式须对同一消息分加密和认证两阶段进行处理,不仅密钥使用量大,而且效率低下.本文基于CBC加密模式设计了一种新的一阶段加密认证方案OXCBC,能够同时提供私密性和认证性,且仅使用一个密钥和一个Nonce,与同类型的加密认证方案相比具有较高的效率.在分组密码是强伪随机置换的假设下,证明了该方案的认证性.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

文中研究由密文的完整性检查而导致的数据保密性问题,提出一个新的安全概念——加密方案在密文验证攻击下的不可区分性(IND-CVA:indistinguishability ofencryption scheme under ciphertext verification attacks)来刻画加密方案在这种情况下的保密安全性。IND-CVA允许敌手访问加密oracle和密文验证oracle。与IND-CPA和IND-CCA相比,IND-CVA比IND-CPA稍微强些,但要比IND-CCA弱得多。IND-CVA能使多数常用的加密方案(如:OTP,CBC,及CTR)得以满足。并且,这个IND-CVA可以恰当地刻画安全信道的保密安全性。将认证方案和加密方案结合起来是保证通信安全的一种常用方法。然而,在IND-CVA模型下,当利用认证方案来加强保密安全性的时候,却有可能反而破坏了原有的保密安全性。IND-CVA揭示了完整性对保密性的影响,准确刻画了安全信道的保密性要求,为协议设计提供了有益的参考。

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Wydział Biologii

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Analysis of the generic attacks and countermeasures for block cipher based message authentication code algorithms (MAC) in sensor applications is undertaken; the conclusions are used in the design of two new MAC constructs Quicker Block Chaining MAC1 (QBC-MAC1) and Quicker Block Chaining MAC2 (QBC-MAC2). Using software simulation we show that our new constructs point to improvements in usage of CPU instruction clock cycle and energy requirement when benchmarked against the de facto Cipher Block Chaining MAC (CBC-MAC) based construct used in the TinySec security protocol for wireless sensor networks.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

A zone based systems design framework is described and utilised in the implementation of a message authentication code (MAC) algorithm based on symmetric key block ciphers. The resulting block cipher based MAC algorithm may be used to provide assurance of the authenticity and, hence, the integrity of binary data. Using software simulation to benchmark against the de facto cipher block chaining MAC (CBC-MAC) variant used in the TinySec security protocol for wireless sensor networks and the NIST cipher block chaining MAC standard, CMAC; we show that our zone based systems design framework can lead to block cipher based MAC constructs that point to improvements in message processing efficiency, processing throughput and processing latency.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

In the space of just 20 years, internal cross-border co-operation (CBC) has transformed from a marginal issue for European integration into an important strand of the third objective of European Union's (EU's) regional policy. How might this process of transformation be explained? This study intends to reconstruct the chronology of its development through interviews and use of archival material. The emergence of the current CBC policy was not, we argue, an inevitable solution to the problem of border management but, rather, the result of a struggle between the actors of that policy sub-system. The dramatic rise of CBC is the result of a series of factors that originated with the signing of the Single European Act in 1986. The construction of CBC as a set of problems and solutions by a network of policy actors at the margins of the EU through a series of technical reports, together with the policy window opened by the appointment of the Delors Commission, allowed the launching of an innovative CBC policy which has consolidated over time.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Despite a low positive predictive value, diagnostic tests such as complete blood count (CBC) and C-reactive protein (CRP) are commonly used to evaluate whether infants with risk factors for early-onset neonatal sepsis (EOS) should be treated with antibiotics. We investigated the impact of implementing a protocol aiming at reducing the number of diagnostic tests in infants with risk factors for EOS in order to compare the diagnostic performance of repeated clinical examination with CBC and CRP measurement. The primary outcome was the time between birth and the first dose of antibiotics in infants treated for suspected EOS. Among the 11,503 infants born at ≥35 weeks during the study period, 222 were treated with antibiotics for suspected EOS. The proportion of infants receiving antibiotics for suspected EOS was 2.1% and 1.7% before and after the change of protocol (p = 0.09). Reduction of diagnostic tests was associated with earlier antibiotic treatment in infants treated for suspected EOS (hazard ratio 1.58; 95% confidence interval [CI] 1.20-2.07; p <0.001), and in infants with neonatal infection (hazard ratio 2.20; 95% CI 1.19-4.06; p = 0.01). There was no difference in the duration of hospital stay nor in the proportion of infants requiring respiratory or cardiovascular support before and after the change of protocol. Reduction of diagnostic tests such as CBC and CRP does not delay initiation of antibiotic treatment in infants with suspected EOS. The importance of clinical examination in infants with risk factors for EOS should be emphasised.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Norah and Fred Fisher welcomed John Fisher into the world on November 29, 1912, not knowing what an influential role he would play in shaping Canada's history. John Fisher grew up as the middle child of five brothers and sisters in Frosty Hollow, New Brunswick, close to today’s town of Sackville. Sackville’s main industry was the Enterprise Foundry which the Fisher family owned and operated; however, Fisher had no plans of going into the family business. He was more inspired by his maternal grandfather, Dr. Cecil Wiggins, who lived with the family after retiring from the Anglican ministry. Wiggins encouraged all his grandchildren to be well read and to take part in discussions on current events. There were often visitors in the Fisher household taking part in discussions about politics, religion, and daily life. Fisher forced himself to take part in these conversations to help overcome his shyness in social settings. These conversations did help with his shyness and also in forming many opinions and observations about Canada. It put Fisher on the road to becoming Mr. Canada and delivering the many eloquent speeches for which he was known. Fisher did not venture far from home to complete his first degree. In 1934 he graduated from Mount Allison University in Sackville, NB with an Arts degree. The same year Fisher enrolled in Dalhousie’s law school. During his time at Dalhousie, Fisher discovered radio through Hugh Mills. Mills or “Uncle Mel” was on CHNS, Halifax’s only radio station at the time. Fisher began by making appearences on the radio drama show. By 1941 he had begun writing and broadcasting his own works and joined the staff as an announcer and continuity writer. In 1936 the Canadian Broadcasting Corporation was formed, the first National radio station. Fisher joined the CBC shortly after it’s beginning and remained with them, as well as the Halifax Herald newspaper, even after his law school graduation in 1937. By 1943 Fisher’s talks became a part of the CBC’s programming for a group of maritime radio stations. Fisher once described his talks as follows “my talks weren’t meant to be objective. . . they were meant to be favourable. They were ‘pride builders’” He began his famed John Fisher Reports at CBC Toronto when he transfered there shortly after the war. This program brought emmence pride to the fellow Canadians he spoke about leading to approximately 3500 requests per year to speak at banquets and meeting throughout Canada and the United States. Fisher was a well travelled indivdual who would draw on personal experiences to connect with his audience. His stories were told in simple, straight forward language for anyone to enjoy. He became a smooth, dynamic and passionate speaker who sold Canada to Canadians. He became a renowned journalist, folk historian, writer and broadcaster. Fisher was able to reach a vast array of people through his radio work and build Canadian pride, but he did not stop there. Other ways Fisher has contributed to Canada and the Canadian people include: Honoured by five Canadian Universities. 1956, became the Director of the Canadian Tourist Association. 1961, was appointed Special Assistant to the Prime Minister of Canada. 1963, Commissioner of the Centennial Commission (the Federal Agency Responsible for Canada’s 100th birthday) 1968, received the Service Medal , a coveted Order of Canada. President of John Fisher Enterprises Ltd., private consultant work, specializing in Centennial planning, broadcasts, lectures and promotion. John Fisher continued recording radio broadcasts even after his diagnosis with cancer. He would record 3 or 4 at a time so he was free to travel across Canada, the U.S., Europe and Mexico in search of treatments. Fisher passed away from the disease on February 15, 1981 and he is buried at Mount Pleasant Cemetery in Toronto.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The pamphlet was originally broadcast over CBC radio March 1, 1942. The inside cover remarks about the public response and the return of the author, Eric Knight to participate in ongoing wartime talks. The pamphlet discusses the life of the British during World War II compared to that of Canadians, "Do you not see that wealth is not money...but a way of living?".