A cryptosystem with non-commutative platform groups based on conjugator search problem was recently introduced at Neural Computing and Applications 2016. Its versatility was illustrated by building a public-key encryp...A cryptosystem with non-commutative platform groups based on conjugator search problem was recently introduced at Neural Computing and Applications 2016. Its versatility was illustrated by building a public-key encryption scheme. We propose an algebraic key-recovery attack in the polynomial computational complexity. Furthermore, we peel off the encryption and decryption process and propose attack methods for solving the conjugator search problem over the given non-abelian group. Finally, we provide corresponding practical attack examples to illustrate the attack methods in our cryptanalysis, and provide some improved suggestions.展开更多
Pneumo-computed tomography (PnCT) is a technique primarily developed and used to study stenotic lesions of the esophagus, gastroesophageal junction and stom-ach for pre-surgical planning. It helps to define both upper...Pneumo-computed tomography (PnCT) is a technique primarily developed and used to study stenotic lesions of the esophagus, gastroesophageal junction and stom-ach for pre-surgical planning. It helps to define both upper and lower borders of neoplasms located in the aforementioned areas. It achieves maximum lumen distension with CO2 highlighting thickened areas of the esophageal wall, thus allowing an accurate quantifica-tion of their extents. Although there are other alterna-tives for distension (oral contrast agents, water and ef-fervescent granules), they may be suboptimal. Patients with locally advanced esophageal cancer have a dismal prognosis despite surgical resection. Therefore, neo-adjuvant treatment strategies using radiation therapy and chemotherapy were developed to improve sur-vival. Neoadjuvant therapy improves esophageal tumor prognosis in a substantial proportion of patients, and the use of imaging techniques is mandatory to detect their response. PnCT combined with virtual endoscopy and multiplanar reconstruction enhances morphologic details in esophageal cancer, and thus would allow animproved assessment of response to neoadjuvant treat-ment. Therefore, more information could be provided to assess the efficacy of pre-surgical treatment. We de-scribe the potential use of PnCT to assess the response to neoadjuvant therapy in esophageal cancer with an imaging pathologic correlation.展开更多
With the development of artificial intelligence(AI)and 5G technology,the integration of sensing,communication and computing in the Internet of Vehicles(Io V)is becoming a trend.However,the large amount of data transmi...With the development of artificial intelligence(AI)and 5G technology,the integration of sensing,communication and computing in the Internet of Vehicles(Io V)is becoming a trend.However,the large amount of data transmission and the computing requirements of intelligent tasks lead to the complex resource management problems.In view of the above challenges,this paper proposes a tasks-oriented joint resource allocation scheme(TOJRAS)in the scenario of Io V.First,this paper proposes a system model with sensing,communication,and computing integration for multiple intelligent tasks with different requirements in the Io V.Secondly,joint resource allocation problems for real-time tasks and delay-tolerant tasks in the Io V are constructed respectively,including communication,computing and caching resources.Thirdly,a distributed deep Q-network(DDQN)based algorithm is proposed to solve the optimization problems,and the convergence and complexity of the algorithm are discussed.Finally,the experimental results based on real data sets verify the performance advantages of the proposed resource allocation scheme,compared to the existing ones.The exploration efficiency of our proposed DDQN-based algorithm is improved by at least about 5%,and our proposed resource allocation scheme improves the m AP performance by about 0.15 under resource constraints.展开更多
Three cases of transient proximal small bowel angioedema induced by intravenous administration of nonionic iodinated contrast media (CM) are presented.Computed tomography (CT) images in the venous phase displayed the ...Three cases of transient proximal small bowel angioedema induced by intravenous administration of nonionic iodinated contrast media (CM) are presented.Computed tomography (CT) images in the venous phase displayed the proximal small bowel with circumferential thickening of the wall including the duodenum and proximal segment of the jejunum.The bowel wall was normal in non-enhanced images,and normal or inconspicuous in arterial phase enhanced images.In one of the three cases,the bowel wall was thickened in venous phase but disappeared in the 40 s delayed phase images.No filling defect was seen in the lumen of the superior mesenteric artery and vein.No peritoneal effusion or mesentery abnormality was found.Each of these patients reported only mild abdominal discomfort and recovered without specific treatment within a short time.Only one patient suffered mild diarrhea after scanning which had resolved by the following day.The transient anaphylactic small bowel angioedema due to intravenous iodinated contrast media was easily diagnosed based on its characteristic CT findings and clinical symptoms.Differential diagnosis may include inflammatory and ischemic bowel disease,as well as neoplasms.A three-phase CT protocol and good under-standing of this disorder are fundamentally important in the diagnosis of this condition.The supposed etiology behind the transient anaphylactic reaction to intravenous administration of iodinated CM in small bowel is similar to other CM-induced hypersensitive immediate reactions.The predilection location of transient anaphylactic bowel angioedema is the small intestine,particularly the proximal segment.A speculated cause may be the richer supply of vessels in the small intestine,ample mucous folds and loose connective tissue in the duodenum and the jejunum.展开更多
A new recursive algorithm with the partial parallel structure based on the linearly constrained minimum variance(LCMV)criterion for adaptive monopulse systems is proposed.The weight vector associated with the original...A new recursive algorithm with the partial parallel structure based on the linearly constrained minimum variance(LCMV)criterion for adaptive monopulse systems is proposed.The weight vector associated with the original whole antenna array is decomposed into several adaptive weight sub-vectors firstly.An adaptive algorithm based on the conventional LCMV principle is then deduced to update the weight sub-vectors for sum and difference beam,respectively.The optimal weight vector can be obtained after convergence.The required computational complexity is evaluated for the proposed technique,which is on the order of O(N)and less than that of the conventional LCMV method.The flow chart scheme with the partial parallel structure of the proposed algorithm is introduced.This scheme is easy to be implemented on a distributed computer/digital signal processor(DSP)system to solve the problems of the heavy computational burden and vast data transmission of the large-scale adaptive monopulse array.Then,the monopulse ratio and convergence rate of the proposed algorithm are evaluated by numerical simulations.Compared with some recent adaptive monopulse estimation methods,a better performance on computational complexity and monopulse ratio can be achieved with the proposed adaptive method.展开更多
Primary tumors of the diaphragm are quite rare. About 150 cases have been reported in the literature. Fibrosarcomas are the commonest malignant neoplasms of the diaphragm; however, only a few(less than 20) cases have ...Primary tumors of the diaphragm are quite rare. About 150 cases have been reported in the literature. Fibrosarcomas are the commonest malignant neoplasms of the diaphragm; however, only a few(less than 20) cases have been reported to date. We present the case of an extremely rare tumor of the diaphragm mimicking a liver mass. The patient, a young 28-year-old woman, presented with an 8-month-history of mildly progressive upper abdominal pain and early fullness after meals. Computed tomography scan of the abdomen revealed a mass located in the region of the left lobe of the liver with non visualized left lobe and partial vascular supply of the mass from the left hepatic artery. The tumor was also seen to draw its vascularity from bilateral internal mammary arteries. Surgical excision and hepatectomy was planned, keeping in mind the diagnosis of an atypical left hepatic mass. Laparotomy revealed a left diaphragmatic tumor growing caudally into the upper abdomen, compressing and splaying the liver along the left medial surface where the tumorwas virtually adherent to it. Successful excision of the mass and subsequent histopathological and immunochemistry examination of the specimen revealed low grade fibromyxoid sarcoma of the diaphragm. This case highlights the unusual presentation of a diaphragmatic mesenchymal tumor and how it can be mistaken as an atypical liver mass. It also emphasizes the tumoral vascular supply as an indicator of its organ of origin.展开更多
Due to high node mobility, stability has been always one of the major concerns of vehicle clustering algorithms in vehicular ad hoc networks. In this paper, we propose a novel clustering algorithm based on the informa...Due to high node mobility, stability has been always one of the major concerns of vehicle clustering algorithms in vehicular ad hoc networks. In this paper, we propose a novel clustering algorithm based on the information of routes planned by vehicular navigation systems. In the clustering algorithm, we design a residual route time function to quantitatively calculate the overlapping time among vehicles based on route information, with which a novel clusterhead selection metric is presented. We further design a mechanism of future-clusterhead, which can help avoid message exchanges at intersections and reduce the overhead of cluster maintenance. The simulation results show that, compared with previous works, our clustering algorithm can achieve higher stability and at the same time lower communication cost.展开更多
Paraneoplastic neurological syndromes(PNS) is a series of rare neurologic disorders which happen with an underlying malignancy. It has various clinical symptoms proceding to the diagnosis of tumors. Although the abnor...Paraneoplastic neurological syndromes(PNS) is a series of rare neurologic disorders which happen with an underlying malignancy. It has various clinical symptoms proceding to the diagnosis of tumors. Although the abnormality of anti-neuronal antibodies is suggestive of PNS and tumors, there exist many false positive and false negative cases. The diagnosis of PNS is usually a challenge in clinic. Positron emission tomography/computed tomography(PET/CT) imaging is an anatomical and functional fusion imaging method, which provides the whole-body information by single scan. Fluorodeoxyglucose(FDG) PET/CT imaging can not only detect potential malignant lesions in the whole body, but also assess functional abnormality in the brain. In this review, the mechanism, clinical manifestation, diagnostic procedure and the recent progress of the utility of FDG PET/CT in PNS are introduced respectively.展开更多
The prevalence of sexual reproduction has long been an outstanding problem of evolutionary biology. Different explanations have been offered to explain the prevalence of sexual reproduction. These explanations mainly ...The prevalence of sexual reproduction has long been an outstanding problem of evolutionary biology. Different explanations have been offered to explain the prevalence of sexual reproduction. These explanations mainly focus on the benefits of sexual reproduction’s ability to shuffle and recombine genes. In this paper, we propose an alternative and comprehensive point of view to this important problem. We first hypothesize that sexual reproduction leads to genetic homogeneity and maintains adaptational advantages of organisms. In stable conditions with strong selective pressures, the maintenance of desired adaptational advantages is one benefit of sexual reproduction. We further hypothesize that sexual reproduction provides a mechanism by which entire populations of similar genomes can interact and collaborate with one another in order to improve the population’s average genomic fitness, a phenomena we call coerced collaborative group evolution. We show that groups of individuals will improve as a whole, even though each individual is still operating under their own best interests. We also argue that the so-called ‘two-fold cost of males’ is misguided if we take limited resources in any environment into consideration. Finally, we propose an intuitive and visualized view to connect different theories on sexual reproduction to establish a comprehensive theory to explain sexual reproduction’s prevalence.展开更多
In this paper, I shall sketch a new way to consider a Lindenbaum-Tarski algebra as a 3D logical space in which any one (of the 256 statements) occupies a well-defined position and it is identified by a numerical ID. T...In this paper, I shall sketch a new way to consider a Lindenbaum-Tarski algebra as a 3D logical space in which any one (of the 256 statements) occupies a well-defined position and it is identified by a numerical ID. This allows pure mechanical computation both for generating rules and inferences. It is shown that this abstract formalism can be geometrically represented with logical spaces and subspaces allowing a vectorial representation. Finally, it shows the application to quantum computing through the example of three coupled harmonic oscillators.展开更多
The field of social computing emerged more than ten years ago. During the last decade, researchers from a vari- ety of disciplines have been closely collaborating to boost the growth of social computing research. This...The field of social computing emerged more than ten years ago. During the last decade, researchers from a vari- ety of disciplines have been closely collaborating to boost the growth of social computing research. This paper aims at iden- tifying key researchers and institutions, and examining the collaboration patterns in the field. We employ co-authorship network analysis at different levels to study the bibliographic information of 6 543 publications in social computing from 1998 to 2011. This paper gives a snapshot of the current re- search in social computing and can provide an initial guid- ance to new researchers in social computing.展开更多
Nowadays,pyogenic liver abscess(PLA)is still a common and severe intra-abdominal infection,and Klebsiella pneumoniae had emerged as the most common pathogenic bacteria worldwide in the past ten years.Our study aims to...Nowadays,pyogenic liver abscess(PLA)is still a common and severe intra-abdominal infection,and Klebsiella pneumoniae had emerged as the most common pathogenic bacteria worldwide in the past ten years.Our study aims to achieve an early pathogenic diagnosis and rational therapy modality for Klebsiella pneumoniae liver abscess(KLA)through clinical data analysis.A total of 197 inpatients in Zhongshan Hospital,Shanghai,diagnosed as having liver abscess between March 2001 and September 2009 were enrolled.Patients with monomicrobial infection were divided into two groups:patients with K.pneumoniae liver abscess(KLA group,n=106)and those with non-Klebsiella pneumoniae liver abscess(NKLA group,n=56).A retrospective analysis was made between these two groups on the aspects of underlying diseases,clinical characteristics,laboratory data,culture results,and imaging findings.To evaluate the effects of different medical interventions,monomicrobial KLA patients were further divided into four subgroups(percutaneous liver aspiration,aspiration plus antibiotics flushing,aspiration plus retained catheter,and aspiration plus antibiotics flushing and retained catheter),and corresponding therapeutic effects were analyzed.KLA was more likely to occur in patients with coexisting diseases such as diabetes mellitus(53.77%vs 25.00%,P=0.001)and hepatic adipose infiltration(16.04%vs 5.36%,P=0.029).Compared to NKLA group,clinical characteristics including abdominal pain(40.57%vs 57.14%,P=0.044),hypodynamia(19.81%vs 46.43%,P=0.001),and hepatomegaly(4.72%vs 14.29%,P=0.033)were much milder,but with a higher fasting blood glucose level(7.84±0.36 vs 5.76±0.30,P=0.001)on admission in KLA group.In addition,KLA abscess often appeared singly in the right lobe of the liver with gas forming nature(32.88%vs 13.51%,P=0.039),unsmooth rim(71.23%vs 40.54%,P=0.002),and dynamic septum enhancement(41.10%vs 16.22%,P=0.009).Compared to mono aspiration subgroup,additional antibiotic flushing could not further improve clinical outcomes of KLA patients(P>0.05);however,the retained catheter showed obvious advantage in reducing abscess diameter(34.38±3.25 mm vs 22.67±2.37 mm,P=0.017).It can be concluded that the strong association with diabetes,milder clinical symptoms,and gas-forming nature in CT images makes early pathogenic diagnosis of KLA possible.Comparatively,ultrasonography-guided percutaneous liver aspiration with retained catheter may be the most rational intervention modality of KLA.展开更多
Trading rules performing well on a given data set seldom lead to promising out-of-sample results, a problem which is a consequence of the in-sample data snooping bias. Efforts to justify the selection of trading rules...Trading rules performing well on a given data set seldom lead to promising out-of-sample results, a problem which is a consequence of the in-sample data snooping bias. Efforts to justify the selection of trading rules by assessing the out-of-sample performance will not really remedy this predica- ment either, because they are prone to be trapped in what is known as the out-of-sample data-snooping bias. Our approach to curb the data-snooping bias consists of constructing a framework for trading rule selection using a-priori robustness strategies, where robustness is gauged on the basis of time- series bootstrap and multi-objective criteria. This approach focuses thus on building robustness into the process of trading rule selection at an early stage, rather than on an ex-post assessment of trading rule fitness. Intra-day FX market data constitute the empirical basis of the proposed investigations. Trading rules are selected from a wide universe created by evolutionary computation tools. The authors show evidence of the benefit of this approach in terms of indirect forecasting accuracy when investing in FX markets.展开更多
We implemented a new protocol—multiphase dynamic helical scan to acquire CT angiography(CTA)and whole brain CT perfusion(CTP)images simulta-neously with single scan on 16 multidetector CT(MDCT).A total of 90 patients...We implemented a new protocol—multiphase dynamic helical scan to acquire CT angiography(CTA)and whole brain CT perfusion(CTP)images simulta-neously with single scan on 16 multidetector CT(MDCT).A total of 90 patients who were randomly assigned into 3 groups were included in our study.Each group underwent CT scan by using the new protocol,traditional CTA and CTP protocol,respectively.The image quality of CTA,the CTP parameter values and the X-ray doses were measured and compared between the new protocol and the traditional protocols.There was no statistically significant difference in the CTA image quality between the above methods(P=0.55).For CTP parameters,the new protocol tended to overestimate the blood volume(BV)and bloodflow(BF)value,and to underestimate the mean transit time(MTT)value compared with the traditional method.However,there was no statistically significant difference in BV,BF,and MTT value between the two methods except permeability surface(PS)(P>0.05).The volume CT dose index(CTDIvol)and dose length product(DLP)of our protocol were lower than the traditional one.The new protocol can obtain valuable diagnostic information in a shorter time without significant compromise in image quality.In addition,it reduces the radiation dose as well as contrast medium usage on the patient.展开更多
基金supported by the State Key Program of National Natural Science of China(Grant Nos. 61332019)the National Natural Science Foundation of China (61572303)+7 种基金National Key Research and Development Program of China ( 2017YFB0802003 , 2017YFB0802004)National Cryptography Development Fund during the 13th Five-year Plan Period (MMJJ20170216)the Foundation of State Key Laboratory of Information Security (2017-MS-03)the Fundamental Research Funds for the Central Universities(GK201702004,GK201603084)Major State Basic Research Development Program of China (973 Program) (No.2014CB340600)National High-tech R&D Program of China(2015AA016002, 2015AA016004)Natural Science Foundation of He Bei Province (No. F2017201199)Science and technology research project of Hebei higher education (No. QN2017020)
文摘A cryptosystem with non-commutative platform groups based on conjugator search problem was recently introduced at Neural Computing and Applications 2016. Its versatility was illustrated by building a public-key encryption scheme. We propose an algebraic key-recovery attack in the polynomial computational complexity. Furthermore, we peel off the encryption and decryption process and propose attack methods for solving the conjugator search problem over the given non-abelian group. Finally, we provide corresponding practical attack examples to illustrate the attack methods in our cryptanalysis, and provide some improved suggestions.
文摘Pneumo-computed tomography (PnCT) is a technique primarily developed and used to study stenotic lesions of the esophagus, gastroesophageal junction and stom-ach for pre-surgical planning. It helps to define both upper and lower borders of neoplasms located in the aforementioned areas. It achieves maximum lumen distension with CO2 highlighting thickened areas of the esophageal wall, thus allowing an accurate quantifica-tion of their extents. Although there are other alterna-tives for distension (oral contrast agents, water and ef-fervescent granules), they may be suboptimal. Patients with locally advanced esophageal cancer have a dismal prognosis despite surgical resection. Therefore, neo-adjuvant treatment strategies using radiation therapy and chemotherapy were developed to improve sur-vival. Neoadjuvant therapy improves esophageal tumor prognosis in a substantial proportion of patients, and the use of imaging techniques is mandatory to detect their response. PnCT combined with virtual endoscopy and multiplanar reconstruction enhances morphologic details in esophageal cancer, and thus would allow animproved assessment of response to neoadjuvant treat-ment. Therefore, more information could be provided to assess the efficacy of pre-surgical treatment. We de-scribe the potential use of PnCT to assess the response to neoadjuvant therapy in esophageal cancer with an imaging pathologic correlation.
基金supported by The Fundamental Research Funds for the Central Universities(No.2021XD-A01-1)The National Natural Science Foundation of China(No.92067202)。
文摘With the development of artificial intelligence(AI)and 5G technology,the integration of sensing,communication and computing in the Internet of Vehicles(Io V)is becoming a trend.However,the large amount of data transmission and the computing requirements of intelligent tasks lead to the complex resource management problems.In view of the above challenges,this paper proposes a tasks-oriented joint resource allocation scheme(TOJRAS)in the scenario of Io V.First,this paper proposes a system model with sensing,communication,and computing integration for multiple intelligent tasks with different requirements in the Io V.Secondly,joint resource allocation problems for real-time tasks and delay-tolerant tasks in the Io V are constructed respectively,including communication,computing and caching resources.Thirdly,a distributed deep Q-network(DDQN)based algorithm is proposed to solve the optimization problems,and the convergence and complexity of the algorithm are discussed.Finally,the experimental results based on real data sets verify the performance advantages of the proposed resource allocation scheme,compared to the existing ones.The exploration efficiency of our proposed DDQN-based algorithm is improved by at least about 5%,and our proposed resource allocation scheme improves the m AP performance by about 0.15 under resource constraints.
文摘Three cases of transient proximal small bowel angioedema induced by intravenous administration of nonionic iodinated contrast media (CM) are presented.Computed tomography (CT) images in the venous phase displayed the proximal small bowel with circumferential thickening of the wall including the duodenum and proximal segment of the jejunum.The bowel wall was normal in non-enhanced images,and normal or inconspicuous in arterial phase enhanced images.In one of the three cases,the bowel wall was thickened in venous phase but disappeared in the 40 s delayed phase images.No filling defect was seen in the lumen of the superior mesenteric artery and vein.No peritoneal effusion or mesentery abnormality was found.Each of these patients reported only mild abdominal discomfort and recovered without specific treatment within a short time.Only one patient suffered mild diarrhea after scanning which had resolved by the following day.The transient anaphylactic small bowel angioedema due to intravenous iodinated contrast media was easily diagnosed based on its characteristic CT findings and clinical symptoms.Differential diagnosis may include inflammatory and ischemic bowel disease,as well as neoplasms.A three-phase CT protocol and good under-standing of this disorder are fundamentally important in the diagnosis of this condition.The supposed etiology behind the transient anaphylactic reaction to intravenous administration of iodinated CM in small bowel is similar to other CM-induced hypersensitive immediate reactions.The predilection location of transient anaphylactic bowel angioedema is the small intestine,particularly the proximal segment.A speculated cause may be the richer supply of vessels in the small intestine,ample mucous folds and loose connective tissue in the duodenum and the jejunum.
基金supported by the National Natural Science Foundation of China(11273017)
文摘A new recursive algorithm with the partial parallel structure based on the linearly constrained minimum variance(LCMV)criterion for adaptive monopulse systems is proposed.The weight vector associated with the original whole antenna array is decomposed into several adaptive weight sub-vectors firstly.An adaptive algorithm based on the conventional LCMV principle is then deduced to update the weight sub-vectors for sum and difference beam,respectively.The optimal weight vector can be obtained after convergence.The required computational complexity is evaluated for the proposed technique,which is on the order of O(N)and less than that of the conventional LCMV method.The flow chart scheme with the partial parallel structure of the proposed algorithm is introduced.This scheme is easy to be implemented on a distributed computer/digital signal processor(DSP)system to solve the problems of the heavy computational burden and vast data transmission of the large-scale adaptive monopulse array.Then,the monopulse ratio and convergence rate of the proposed algorithm are evaluated by numerical simulations.Compared with some recent adaptive monopulse estimation methods,a better performance on computational complexity and monopulse ratio can be achieved with the proposed adaptive method.
文摘Primary tumors of the diaphragm are quite rare. About 150 cases have been reported in the literature. Fibrosarcomas are the commonest malignant neoplasms of the diaphragm; however, only a few(less than 20) cases have been reported to date. We present the case of an extremely rare tumor of the diaphragm mimicking a liver mass. The patient, a young 28-year-old woman, presented with an 8-month-history of mildly progressive upper abdominal pain and early fullness after meals. Computed tomography scan of the abdomen revealed a mass located in the region of the left lobe of the liver with non visualized left lobe and partial vascular supply of the mass from the left hepatic artery. The tumor was also seen to draw its vascularity from bilateral internal mammary arteries. Surgical excision and hepatectomy was planned, keeping in mind the diagnosis of an atypical left hepatic mass. Laparotomy revealed a left diaphragmatic tumor growing caudally into the upper abdomen, compressing and splaying the liver along the left medial surface where the tumorwas virtually adherent to it. Successful excision of the mass and subsequent histopathological and immunochemistry examination of the specimen revealed low grade fibromyxoid sarcoma of the diaphragm. This case highlights the unusual presentation of a diaphragmatic mesenchymal tumor and how it can be mistaken as an atypical liver mass. It also emphasizes the tumoral vascular supply as an indicator of its organ of origin.
基金partially supported by The National Key Research and Development Program of China(No.2016YFB0200404)National Natural Science Foundation of China(No.61501527,61379157,U1711263)+6 种基金MOE-CMCC Joint Research Fund of China(No.MCM20160104)State’s Key Project of Research and Development Plan(No.2016YFE01229003)the Fundamental Research Funds for the Central Universitiesthe Science,Technology and Innovation Commission of Shenzhen Municipality(JCYJ20160429170032960)Guangdong Science and Technology Project(No.2016B010126003)2016 Major Project of Collaborative Innovation in Guangzhou(No.201604046008)Program of Science and Technology of Guangdong(No.2015B010111001)
文摘Due to high node mobility, stability has been always one of the major concerns of vehicle clustering algorithms in vehicular ad hoc networks. In this paper, we propose a novel clustering algorithm based on the information of routes planned by vehicular navigation systems. In the clustering algorithm, we design a residual route time function to quantitatively calculate the overlapping time among vehicles based on route information, with which a novel clusterhead selection metric is presented. We further design a mechanism of future-clusterhead, which can help avoid message exchanges at intersections and reduce the overhead of cluster maintenance. The simulation results show that, compared with previous works, our clustering algorithm can achieve higher stability and at the same time lower communication cost.
基金Supported by grants from the National Natural Science Foundation of China(No.81101065,31100604)Higher Education Doctoral Program of China Research Fund for New Teacher(No.20110001120043)+1 种基金National Major Scientific Equipment Special Fund(No.2011YQ03011409)Beijing Capital Special Development Application Program(No.Z141107002514159)
文摘Paraneoplastic neurological syndromes(PNS) is a series of rare neurologic disorders which happen with an underlying malignancy. It has various clinical symptoms proceding to the diagnosis of tumors. Although the abnormality of anti-neuronal antibodies is suggestive of PNS and tumors, there exist many false positive and false negative cases. The diagnosis of PNS is usually a challenge in clinic. Positron emission tomography/computed tomography(PET/CT) imaging is an anatomical and functional fusion imaging method, which provides the whole-body information by single scan. Fluorodeoxyglucose(FDG) PET/CT imaging can not only detect potential malignant lesions in the whole body, but also assess functional abnormality in the brain. In this review, the mechanism, clinical manifestation, diagnostic procedure and the recent progress of the utility of FDG PET/CT in PNS are introduced respectively.
文摘The prevalence of sexual reproduction has long been an outstanding problem of evolutionary biology. Different explanations have been offered to explain the prevalence of sexual reproduction. These explanations mainly focus on the benefits of sexual reproduction’s ability to shuffle and recombine genes. In this paper, we propose an alternative and comprehensive point of view to this important problem. We first hypothesize that sexual reproduction leads to genetic homogeneity and maintains adaptational advantages of organisms. In stable conditions with strong selective pressures, the maintenance of desired adaptational advantages is one benefit of sexual reproduction. We further hypothesize that sexual reproduction provides a mechanism by which entire populations of similar genomes can interact and collaborate with one another in order to improve the population’s average genomic fitness, a phenomena we call coerced collaborative group evolution. We show that groups of individuals will improve as a whole, even though each individual is still operating under their own best interests. We also argue that the so-called ‘two-fold cost of males’ is misguided if we take limited resources in any environment into consideration. Finally, we propose an intuitive and visualized view to connect different theories on sexual reproduction to establish a comprehensive theory to explain sexual reproduction’s prevalence.
文摘In this paper, I shall sketch a new way to consider a Lindenbaum-Tarski algebra as a 3D logical space in which any one (of the 256 statements) occupies a well-defined position and it is identified by a numerical ID. This allows pure mechanical computation both for generating rules and inferences. It is shown that this abstract formalism can be geometrically represented with logical spaces and subspaces allowing a vectorial representation. Finally, it shows the application to quantum computing through the example of three coupled harmonic oscillators.
文摘The field of social computing emerged more than ten years ago. During the last decade, researchers from a vari- ety of disciplines have been closely collaborating to boost the growth of social computing research. This paper aims at iden- tifying key researchers and institutions, and examining the collaboration patterns in the field. We employ co-authorship network analysis at different levels to study the bibliographic information of 6 543 publications in social computing from 1998 to 2011. This paper gives a snapshot of the current re- search in social computing and can provide an initial guid- ance to new researchers in social computing.
文摘Nowadays,pyogenic liver abscess(PLA)is still a common and severe intra-abdominal infection,and Klebsiella pneumoniae had emerged as the most common pathogenic bacteria worldwide in the past ten years.Our study aims to achieve an early pathogenic diagnosis and rational therapy modality for Klebsiella pneumoniae liver abscess(KLA)through clinical data analysis.A total of 197 inpatients in Zhongshan Hospital,Shanghai,diagnosed as having liver abscess between March 2001 and September 2009 were enrolled.Patients with monomicrobial infection were divided into two groups:patients with K.pneumoniae liver abscess(KLA group,n=106)and those with non-Klebsiella pneumoniae liver abscess(NKLA group,n=56).A retrospective analysis was made between these two groups on the aspects of underlying diseases,clinical characteristics,laboratory data,culture results,and imaging findings.To evaluate the effects of different medical interventions,monomicrobial KLA patients were further divided into four subgroups(percutaneous liver aspiration,aspiration plus antibiotics flushing,aspiration plus retained catheter,and aspiration plus antibiotics flushing and retained catheter),and corresponding therapeutic effects were analyzed.KLA was more likely to occur in patients with coexisting diseases such as diabetes mellitus(53.77%vs 25.00%,P=0.001)and hepatic adipose infiltration(16.04%vs 5.36%,P=0.029).Compared to NKLA group,clinical characteristics including abdominal pain(40.57%vs 57.14%,P=0.044),hypodynamia(19.81%vs 46.43%,P=0.001),and hepatomegaly(4.72%vs 14.29%,P=0.033)were much milder,but with a higher fasting blood glucose level(7.84±0.36 vs 5.76±0.30,P=0.001)on admission in KLA group.In addition,KLA abscess often appeared singly in the right lobe of the liver with gas forming nature(32.88%vs 13.51%,P=0.039),unsmooth rim(71.23%vs 40.54%,P=0.002),and dynamic septum enhancement(41.10%vs 16.22%,P=0.009).Compared to mono aspiration subgroup,additional antibiotic flushing could not further improve clinical outcomes of KLA patients(P>0.05);however,the retained catheter showed obvious advantage in reducing abscess diameter(34.38±3.25 mm vs 22.67±2.37 mm,P=0.017).It can be concluded that the strong association with diabetes,milder clinical symptoms,and gas-forming nature in CT images makes early pathogenic diagnosis of KLA possible.Comparatively,ultrasonography-guided percutaneous liver aspiration with retained catheter may be the most rational intervention modality of KLA.
文摘Trading rules performing well on a given data set seldom lead to promising out-of-sample results, a problem which is a consequence of the in-sample data snooping bias. Efforts to justify the selection of trading rules by assessing the out-of-sample performance will not really remedy this predica- ment either, because they are prone to be trapped in what is known as the out-of-sample data-snooping bias. Our approach to curb the data-snooping bias consists of constructing a framework for trading rule selection using a-priori robustness strategies, where robustness is gauged on the basis of time- series bootstrap and multi-objective criteria. This approach focuses thus on building robustness into the process of trading rule selection at an early stage, rather than on an ex-post assessment of trading rule fitness. Intra-day FX market data constitute the empirical basis of the proposed investigations. Trading rules are selected from a wide universe created by evolutionary computation tools. The authors show evidence of the benefit of this approach in terms of indirect forecasting accuracy when investing in FX markets.
文摘We implemented a new protocol—multiphase dynamic helical scan to acquire CT angiography(CTA)and whole brain CT perfusion(CTP)images simulta-neously with single scan on 16 multidetector CT(MDCT).A total of 90 patients who were randomly assigned into 3 groups were included in our study.Each group underwent CT scan by using the new protocol,traditional CTA and CTP protocol,respectively.The image quality of CTA,the CTP parameter values and the X-ray doses were measured and compared between the new protocol and the traditional protocols.There was no statistically significant difference in the CTA image quality between the above methods(P=0.55).For CTP parameters,the new protocol tended to overestimate the blood volume(BV)and bloodflow(BF)value,and to underestimate the mean transit time(MTT)value compared with the traditional method.However,there was no statistically significant difference in BV,BF,and MTT value between the two methods except permeability surface(PS)(P>0.05).The volume CT dose index(CTDIvol)and dose length product(DLP)of our protocol were lower than the traditional one.The new protocol can obtain valuable diagnostic information in a shorter time without significant compromise in image quality.In addition,it reduces the radiation dose as well as contrast medium usage on the patient.
