Pub Date : 2008-09-01DOI: 10.1109/ALLERTON.2008.4797594
Urs Niesen, P. Gupta, D. Shah
The capacity region of a wireless network with n nodes is the set of all simultaneously achievable rates between all possible n2 node pairs. In this paper, we consider the question of determining the scaling, with respect to the number of nodes n, of the capacity region when the nodes are placed uniformly at random in a square region of area n and they communicate over Gaussian channels. We identify this scaling of the capacity region in terms of Theta(n), out of 2n total possible, cuts. Our results are constructive and provide optimal (in the scaling sense) communication schemes. In the case of a restricted class of traffic requirement (permutation traffic), we determine the precise scaling in terms of a natural generalization of the transport capacity. We illustrate the strength of these results by computing the capacity scaling in a number of scenarios with non-uniform traffic patterns for which no such results have been available before.
{"title":"The capacity region of large wireless networks","authors":"Urs Niesen, P. Gupta, D. Shah","doi":"10.1109/ALLERTON.2008.4797594","DOIUrl":"https://doi.org/10.1109/ALLERTON.2008.4797594","url":null,"abstract":"The capacity region of a wireless network with n nodes is the set of all simultaneously achievable rates between all possible n2 node pairs. In this paper, we consider the question of determining the scaling, with respect to the number of nodes n, of the capacity region when the nodes are placed uniformly at random in a square region of area n and they communicate over Gaussian channels. We identify this scaling of the capacity region in terms of Theta(n), out of 2n total possible, cuts. Our results are constructive and provide optimal (in the scaling sense) communication schemes. In the case of a restricted class of traffic requirement (permutation traffic), we determine the precise scaling in terms of a natural generalization of the transport capacity. We illustrate the strength of these results by computing the capacity scaling in a number of scenarios with non-uniform traffic patterns for which no such results have been available before.","PeriodicalId":120561,"journal":{"name":"2008 46th Annual Allerton Conference on Communication, Control, and Computing","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129991856","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2008-09-01DOI: 10.1109/ALLERTON.2008.4797584
Eitan Yaakobi, A. Vardy, P. Siegel, J. Wolf
Flash memory is a non-volatile computer memory comprised of blocks of cells, wherein each cell can take on q different levels corresponding to the number of electrons it contains. Increasing the cell level is easy; however, reducing a cell level forces all the other cells in the same block to be erased. This erasing operation is undesirable and therefore has to be used as infrequently as possible. We consider the problem of designing codes for this purpose, where k bits are stored using a block of n cells with q levels each. The goal is to maximize the number of bit writes before an erase operation is required. We present an efficient construction of codes that can store an arbitrary number of bits. Our construction can be viewed as an extension to multiple dimensions of the earlier work of Jiang and Bruck, where single-dimensional codes that can store only 2 bits were proposed.
{"title":"Multidimensional flash codes","authors":"Eitan Yaakobi, A. Vardy, P. Siegel, J. Wolf","doi":"10.1109/ALLERTON.2008.4797584","DOIUrl":"https://doi.org/10.1109/ALLERTON.2008.4797584","url":null,"abstract":"Flash memory is a non-volatile computer memory comprised of blocks of cells, wherein each cell can take on q different levels corresponding to the number of electrons it contains. Increasing the cell level is easy; however, reducing a cell level forces all the other cells in the same block to be erased. This erasing operation is undesirable and therefore has to be used as infrequently as possible. We consider the problem of designing codes for this purpose, where k bits are stored using a block of n cells with q levels each. The goal is to maximize the number of bit writes before an erase operation is required. We present an efficient construction of codes that can store an arbitrary number of bits. Our construction can be viewed as an extension to multiple dimensions of the earlier work of Jiang and Bruck, where single-dimensional codes that can store only 2 bits were proposed.","PeriodicalId":120561,"journal":{"name":"2008 46th Annual Allerton Conference on Communication, Control, and Computing","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130455295","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2008-09-01DOI: 10.1109/ALLERTON.2008.4797543
Z. Utkovski, P. Chen, J. Lindner
Geometric methods for construction of codes in the Grassmann manifolds are presented. The methods follow the geometric approach to space-time coding for the non-coherent MIMO channel where the code design is interpreted as a packing problem on Grassmann manifolds. The differential structure of the Grassmann manifold provides parametrization with the tangent space at the identity element. Grassmann codes for the non-coherent channel are constructed by mapping suitable subsets of lattices from the tangent space to the Grassmann manifold via the exponential map. As examples, constructions from the rotated Gosset, Barnes-Wall and Leech lattice are presented. Due to the specifics of the mapping, some of the structure is preserved after the mapping to the manifold. The method is further improved by modifying the mapping from the tangent space to the manifold. Ideas for other constructions of Grassmann codes are also presented and discussed.
{"title":"Some geometric methods for construction of space-time codes in Grassmann manifolds","authors":"Z. Utkovski, P. Chen, J. Lindner","doi":"10.1109/ALLERTON.2008.4797543","DOIUrl":"https://doi.org/10.1109/ALLERTON.2008.4797543","url":null,"abstract":"Geometric methods for construction of codes in the Grassmann manifolds are presented. The methods follow the geometric approach to space-time coding for the non-coherent MIMO channel where the code design is interpreted as a packing problem on Grassmann manifolds. The differential structure of the Grassmann manifold provides parametrization with the tangent space at the identity element. Grassmann codes for the non-coherent channel are constructed by mapping suitable subsets of lattices from the tangent space to the Grassmann manifold via the exponential map. As examples, constructions from the rotated Gosset, Barnes-Wall and Leech lattice are presented. Due to the specifics of the mapping, some of the structure is preserved after the mapping to the manifold. The method is further improved by modifying the mapping from the tangent space to the manifold. Ideas for other constructions of Grassmann codes are also presented and discussed.","PeriodicalId":120561,"journal":{"name":"2008 46th Annual Allerton Conference on Communication, Control, and Computing","volume":"34 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126332647","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2008-09-01DOI: 10.1109/ALLERTON.2008.4797546
M. Zoltowski, T. Qureshi, R. Calderbank
We present a pilot-assisted method for estimating the frequency selective channel in a MIMO-OFDM (multiple input multiple output -orthogonal frequency division multiplexing) system. The pilot sequence is designed using the DFT (discrete Fourier transform) of the Golay complementary sequences. Novel exploitation of the perfect autocorrelation property of the Golay codes, in conjunction with OSTBC (orthogonal space-time block code) based pilot waveform scheduling across multiple OFDM frames, facilitates simple separation of the channel mixtures at the receive antennas. The DFT length used to transform the complementary sequence into the frequency domain is shown to be a key critical parameter for correctly estimating the channel. NMSE (normalized mean squared error) between the actual and the estimated channel is used to characterize the estimation performance.
{"title":"Complementary codes based channel estimation for MIMO-OFDM systems","authors":"M. Zoltowski, T. Qureshi, R. Calderbank","doi":"10.1109/ALLERTON.2008.4797546","DOIUrl":"https://doi.org/10.1109/ALLERTON.2008.4797546","url":null,"abstract":"We present a pilot-assisted method for estimating the frequency selective channel in a MIMO-OFDM (multiple input multiple output -orthogonal frequency division multiplexing) system. The pilot sequence is designed using the DFT (discrete Fourier transform) of the Golay complementary sequences. Novel exploitation of the perfect autocorrelation property of the Golay codes, in conjunction with OSTBC (orthogonal space-time block code) based pilot waveform scheduling across multiple OFDM frames, facilitates simple separation of the channel mixtures at the receive antennas. The DFT length used to transform the complementary sequence into the frequency domain is shown to be a key critical parameter for correctly estimating the channel. NMSE (normalized mean squared error) between the actual and the estimated channel is used to characterize the estimation performance.","PeriodicalId":120561,"journal":{"name":"2008 46th Annual Allerton Conference on Communication, Control, and Computing","volume":"C-33 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126487340","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2008-09-01DOI: 10.1109/ALLERTON.2008.4797708
A. Kirsch, M. Mitzenmacher
In a multiple choice hash table scheme, each item is stored in one of d ges 2 hash table buckets. The ability to choose from multiple locations when storing an item improves space utilization, while the simplicity of such schemes makes them highly amenable to hardware implementation, as in a router. Some variants, such as cuckoo hashing, allow items to be moved among their d choices in order to improve load balance and avoid hash table overflows. We consider schemes that move items on insertion and deletion operations, as arguably one would be willing to incur more time on such operations as opposed to more frequent lookup operations. To keep the schemes as simple as possible for hardware implementation, we focus on schemes that allow a single move on an insertion or deletion. Our results show significant space savings when moving items is allowed, even under the limitation of one move per insertion and deletion operation.
{"title":"On the performance of multiple choice hash tables with moves on deletes and inserts","authors":"A. Kirsch, M. Mitzenmacher","doi":"10.1109/ALLERTON.2008.4797708","DOIUrl":"https://doi.org/10.1109/ALLERTON.2008.4797708","url":null,"abstract":"In a multiple choice hash table scheme, each item is stored in one of d ges 2 hash table buckets. The ability to choose from multiple locations when storing an item improves space utilization, while the simplicity of such schemes makes them highly amenable to hardware implementation, as in a router. Some variants, such as cuckoo hashing, allow items to be moved among their d choices in order to improve load balance and avoid hash table overflows. We consider schemes that move items on insertion and deletion operations, as arguably one would be willing to incur more time on such operations as opposed to more frequent lookup operations. To keep the schemes as simple as possible for hardware implementation, we focus on schemes that allow a single move on an insertion or deletion. Our results show significant space savings when moving items is allowed, even under the limitation of one move per insertion and deletion operation.","PeriodicalId":120561,"journal":{"name":"2008 46th Annual Allerton Conference on Communication, Control, and Computing","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129070289","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2008-09-01DOI: 10.1109/ALLERTON.2008.4797690
A. Aram, S. Sarkar, C. Singh, Anurag Kumar
We consider a framework in which several service providers offer downlink wireless data access service in a certain area. Each provider serves its end-users through opportunistic secondary spectrum access of licensed spectrum, and needs to pay primary license holders of the spectrum usage based and membership based charges for such secondary spectrum access. In these circumstances, if providers pool their resources and allow end-users to be served by any of the cooperating providers, the total user satisfaction as well as the aggregate revenue earned by providers may increase. We use coalitional game theory to investigate such cooperation among providers, and show that the optimal cooperation schemes can be obtained as solutions of convex optimizations. We next show that under usage based charging scheme, if all providers cooperate, there always exists an operating point that maximizes the aggregate revenue of providers, while presenting each provider a share of the revenue such that no subset of providers has an incentive to leave the coalition. Furthermore, such an operating point can be computed in polynomial time. Finally, we show that when the charging scheme involves membership based charges, the above result holds in important special cases.
{"title":"A coalitional game framework for cooperative secondary spectrum access","authors":"A. Aram, S. Sarkar, C. Singh, Anurag Kumar","doi":"10.1109/ALLERTON.2008.4797690","DOIUrl":"https://doi.org/10.1109/ALLERTON.2008.4797690","url":null,"abstract":"We consider a framework in which several service providers offer downlink wireless data access service in a certain area. Each provider serves its end-users through opportunistic secondary spectrum access of licensed spectrum, and needs to pay primary license holders of the spectrum usage based and membership based charges for such secondary spectrum access. In these circumstances, if providers pool their resources and allow end-users to be served by any of the cooperating providers, the total user satisfaction as well as the aggregate revenue earned by providers may increase. We use coalitional game theory to investigate such cooperation among providers, and show that the optimal cooperation schemes can be obtained as solutions of convex optimizations. We next show that under usage based charging scheme, if all providers cooperate, there always exists an operating point that maximizes the aggregate revenue of providers, while presenting each provider a share of the revenue such that no subset of providers has an incentive to leave the coalition. Furthermore, such an operating point can be computed in polynomial time. Finally, we show that when the charging scheme involves membership based charges, the above result holds in important special cases.","PeriodicalId":120561,"journal":{"name":"2008 46th Annual Allerton Conference on Communication, Control, and Computing","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121039084","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2008-09-01DOI: 10.1109/ALLERTON.2008.4797593
D. Du, W. Bhosri, A. Frazho
In this paper, we reformulate the design of IIR synthesis filters in classical multirate systems as an optimization problem involving a new norm called Pm-norm where m is any positive integer. That optimization problem can be solved using a recent generalization of the commutant lifting techniques in operator theory. The introduced norm is actually a trade-off in handling energy distortion and error peak distortion. Our development allows the designer to select from a family of filters the one which is best suited for specific applications. The well-known H2 and Hinfin designs then can be viewed as special cases when m=1 and mrarrinfin respectively. The computation relies mainly on FFT technique and a finite section of certain Toeplitz matrices. The obtained filters are of low order and attractive for practical implementation. Moreover, the proposed approach works for non-rational transfer functions. A new method for inner outer factorization of a rational matrix-valued function is also developed.
{"title":"Mixed norm low order multirate filterbank design: Relaxed commutant lifting approach","authors":"D. Du, W. Bhosri, A. Frazho","doi":"10.1109/ALLERTON.2008.4797593","DOIUrl":"https://doi.org/10.1109/ALLERTON.2008.4797593","url":null,"abstract":"In this paper, we reformulate the design of IIR synthesis filters in classical multirate systems as an optimization problem involving a new norm called Pm-norm where m is any positive integer. That optimization problem can be solved using a recent generalization of the commutant lifting techniques in operator theory. The introduced norm is actually a trade-off in handling energy distortion and error peak distortion. Our development allows the designer to select from a family of filters the one which is best suited for specific applications. The well-known H2 and Hinfin designs then can be viewed as special cases when m=1 and mrarrinfin respectively. The computation relies mainly on FFT technique and a finite section of certain Toeplitz matrices. The obtained filters are of low order and attractive for practical implementation. Moreover, the proposed approach works for non-rational transfer functions. A new method for inner outer factorization of a rational matrix-valued function is also developed.","PeriodicalId":120561,"journal":{"name":"2008 46th Annual Allerton Conference on Communication, Control, and Computing","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121386942","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2008-09-01DOI: 10.1109/ALLERTON.2008.4797670
E. Ekrem, S. Ulukus
We develop an outer bound for the secrecy capacity region of a class of multiple access wiretap channels (MAC-WT). In this class, which we call the weak eavesdropper class, each user's link to the legitimate receiver is stronger than its link to the eavesdropper. Our outer bound partially matches the achievable region in an n-letter form. In addition, a looser version of our outer bound provides close approximations to the capacity region of the Gaussian MAC-WT channel. In particular, we prove that our outer bound is within 0.5 bits/channel use of the achievable rates along the individual rates for all weak eavesdropper Gaussian MAC-WT, and within 0.5 bits/channel use in all directions for certain weak eavesdropper Gaussian MAC-WT channels.
{"title":"On the secrecy of multiple access wiretap channel","authors":"E. Ekrem, S. Ulukus","doi":"10.1109/ALLERTON.2008.4797670","DOIUrl":"https://doi.org/10.1109/ALLERTON.2008.4797670","url":null,"abstract":"We develop an outer bound for the secrecy capacity region of a class of multiple access wiretap channels (MAC-WT). In this class, which we call the weak eavesdropper class, each user's link to the legitimate receiver is stronger than its link to the eavesdropper. Our outer bound partially matches the achievable region in an n-letter form. In addition, a looser version of our outer bound provides close approximations to the capacity region of the Gaussian MAC-WT channel. In particular, we prove that our outer bound is within 0.5 bits/channel use of the achievable rates along the individual rates for all weak eavesdropper Gaussian MAC-WT, and within 0.5 bits/channel use in all directions for certain weak eavesdropper Gaussian MAC-WT channels.","PeriodicalId":120561,"journal":{"name":"2008 46th Annual Allerton Conference on Communication, Control, and Computing","volume":"63 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122735215","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2008-09-01DOI: 10.1109/ALLERTON.2008.4797537
Alireza Seyedi
A Markov based unified model for energy harvesting nodes in wireless sensor networks is proposed. Using the presented model, the probability of event loss due to energy run out as well as an analytical vulnerability metric, namely average time to energy run-out, are derived. The results provide insight into the performance of energy harvesting nodes in wireless sensor networks as well as design requirements for such nodes. The proposed vulnerability metric can be used in the various harvesting aware techniques at different protocol layers.
{"title":"Modeling and analysis of energy harvesting nodes in wireless sensor networks","authors":"Alireza Seyedi","doi":"10.1109/ALLERTON.2008.4797537","DOIUrl":"https://doi.org/10.1109/ALLERTON.2008.4797537","url":null,"abstract":"A Markov based unified model for energy harvesting nodes in wireless sensor networks is proposed. Using the presented model, the probability of event loss due to energy run out as well as an analytical vulnerability metric, namely average time to energy run-out, are derived. The results provide insight into the performance of energy harvesting nodes in wireless sensor networks as well as design requirements for such nodes. The proposed vulnerability metric can be used in the various harvesting aware techniques at different protocol layers.","PeriodicalId":120561,"journal":{"name":"2008 46th Annual Allerton Conference on Communication, Control, and Computing","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122814879","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this paper we study a generalized model for quantity (Cournot) oligopolistic competition. The main goal in this paper is to understand Cournot competition when firms are producing multiple differentiated products and are faced with a variety of constraints. We first study existence and uniqueness of Cournot equilibria under general constraints. The main focus of the paper is to compare the total society surplus and the total firms' profit under Cournot competition to the corresponding total surplus and total profit of the firms under a centralized setting, (i.e., when a single firm controls all the products in the market maximizing total surplus or total profit respectively). Our goal is to understand how the presence of competition affects the overall society (that includes firms and consumers) as well as the overall firms' profit in the system, but also determine what the key drivers of the inefficiencies that arise due to competition are.
{"title":"Generalized quantity competition for multiple products and loss of efficiency","authors":"Jonathan Kluberg, G. Perakis","doi":"10.1287/opre.1110.1017","DOIUrl":"https://doi.org/10.1287/opre.1110.1017","url":null,"abstract":"In this paper we study a generalized model for quantity (Cournot) oligopolistic competition. The main goal in this paper is to understand Cournot competition when firms are producing multiple differentiated products and are faced with a variety of constraints. We first study existence and uniqueness of Cournot equilibria under general constraints. The main focus of the paper is to compare the total society surplus and the total firms' profit under Cournot competition to the corresponding total surplus and total profit of the firms under a centralized setting, (i.e., when a single firm controls all the products in the market maximizing total surplus or total profit respectively). Our goal is to understand how the presence of competition affects the overall society (that includes firms and consumers) as well as the overall firms' profit in the system, but also determine what the key drivers of the inefficiencies that arise due to competition are.","PeriodicalId":120561,"journal":{"name":"2008 46th Annual Allerton Conference on Communication, Control, and Computing","volume":"108 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117287764","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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