聚合干扰下小小区网络的协作传输方案及性能分析

该文针对聚合干扰下小小区网络协作传输的场景,分析了宏小区基站的物理位置服从泊松分布,且多用户预编码采用线性预编码时用户端的性能。通过基于概率密度函数的性能分析法,推导出小小区网络协作传输的中断概率、容量以及误符号率的闭合表达式,结果表明由于聚合干扰的存在,仅仅依靠小小区网络基站天线数的增加并不能持续提高用户端的性能。进一步,针对小小区网络中用户的接入问题,提出了一种基于能效最大化的用户接入方案,并对所提方案进行了性能分析和仿真验证,从结果可以看到所提小小区网络用户接入方案在提高系统能效方面要优于其他接入方案,仿真结果验证了基于能效最大化的接入方案的优越性,并验证了本文理论分析的正确性。

能量收集增强型无人机中继辅助传输设计

针对无人机(Unmanned Aerial Vehicles,UAV)中继辅助通信系统中,源和目的节点之间的信息传输由于大尺度衰落等原因故需要无人机作为中继进行辅助完成,其中无人机中继采用时间切换和功率分配的方式进行能量收集(Energy Harvesting,EH),且利用最大化系统链路信噪比的无人机中继选择策略。利用概率密度函数分析法推导了终端在收到无人机中继传输的信息后,受到环境中聚合干扰情况下,系统的中断概率闭合表达式。在此基础上利用Q函数得到了系统的误码率。此外分析了终端在受到聚合干扰以及延迟受限状态下系统的中断概率和吞吐量。结果表明所提出的比例因子、发射功率和无人机中继选择的多参数联合优化可有效提升系统的吞吐量并降低系统的中断概率和误码率。仿真验证了所提方案的有效性和理论分析的正确性,联合优化方案可以有效地提升系统性能。

Unperturbed dimensions of atactic poly(dibenzyl itaconate)s

The unperturbed dimension and temperature character of poly(dibenzyl itaconate)s (PDBzI) are studied by a revised rotational isomeric state (RIS) method. The improved formulas of the mean-square radius of gyration, deduced by the pseudo-stereochemical equilibrium approach, may be used to investigate the configurational-conformational properties of atactic polymers with large side groups [poly(itaconates) for instance]. The calculated results showed that poly(itaconates) have larger dimension of the molecule than other vinyl polymers. Comparison of the dimension between considering and without considering side groups showed that the effect of large side groups on the unperturbed dimension for short-chain polymers is more obvious than that of long-chain polymers and, if the dimension of side groups increases, the effect also increases. The dimension differences of PDBzI between short-chain and long-chain polymers are investigated by the relation of characteristic ratios and temperature coefficients with temperature. Moreover, the dependence between the temperature coefficients and the tacticity of chains shows that the temperature characters of the isotactic, syndiotactic and atactic PDBzI chains have remarkable difference.

Suppression of matrix metalloproteinase-2 via RNA interference inhibits pancreatic carcinoma cell invasiveness and adhesion

AIM:To investigate the inhibitory effects of RNA interference (RNAi) on expression of matrix metalloproteinase-2 (MMP-2) gene and invasiveness and adhesion of human pancreatic cancer cell line,BxPC-3.METHODS:RNAi was performed using the vector (pGPU6)-based small interference RNA (siRNA) plasmid gene silence system to specifically knock down MMP-2 expression in pancreatic cancer cell line,BxPC-3. Four groups of different specific target sequence in coding region of MMP-2 and one non-specific sequence were chosen to construct four experimental siRNA plasmids of pGPU6-1,pGPU6-2,pGPU6-3 and pGPU6-4,and one negative control siRNA plasmid of pGPU6 (-). MMP-2 expression was measured by reverse transcription polymerase chain reaction (RT-PCR) and Western blot. Cell proliferation and apoptosis were examined by methyl thiazolyl tetrazolium (MTT) and flow cytometry,respectively. The abilities of adhesion and invasion were detected by cell adhesion assay and cell invasion assay using Transwell chambers.RESULTS:The expression of MMP-2 was inhibited and the inhibitory effects of different sequence varied. pGPU6-1 group had the most efficient inhibitory effect,followed by pGPU6-2 and pGPU6-3 groups.Invasiveness and adhesion were more significantly reduced in pGPU6-1,pGPU6-2 and pGPU6-3 groups as compared with pGPU6 (-) and blank control groups. However,no difference concerning cell proliferation and apoptosis was observed after transfection between experiment groups and control groups.CONCLUSION:RNAi against MMP-2 successfully inhibited the mRNA and protein expression of MMP-2 in the pancreatic cancer cell line,BxPC-3,leading to a potent suppression of tumor cell adhesion and invasion without affecting cell proliferation and apoptosis. These findings suggest that the RNAi approach towards MMP-2 may be an effective therapeutic strategy for the clinical management of pancreatic tumor.

Pure red cell aplasia caused by pegylated interferon-α-2a plus ribavirin in the treatment of chronic hepatitis C

Pure red cell aplasia (PRCA) is a rare hematological disorder which is characterized by severe anemia,reticulocytopenia and almost complete absence of erythroid precursors in bone marrow.The pathophysiology of PRCA may be congenital or acquired.To our knowledge,there is only one case report in the English literature of PRCA after pegylated interferon combination therapy for chronic hepatitis C.We report a second case of PRCA after pegylated interferon combination treatment for chronic hepatitis C.The diagnosis of PRCA was confirmed by the typical findings of bone marrow biopsy.The possible etiologies of our case are also discussed in this paper.

RNA interference with DNA polymerase and synthesis

RNA can catalyze and participate in many chemical and biochemical reactions. Non-coding RNAs （ncRNA） can regulate cellular transcription and translation reactions. We have demonstrated biochemically that RNA can also interfere with DNA polymerization via transforming DNA polymerase into deoxyribonucleoside triphosphate diphosphatase （dNTP-DPase）. RNA, even with six nucleotides, can transform DNA polymerase into dNTP-DPase, and the dNTP-DPase activity causes the hydrolysis of dNTPs into dNMPs and pyrophosphate. Moreover, we have found that DNA polymerases from several families generally have similar RNA-dependent dNTP-DPase activity. We have also observed that in the presence of RNA, when the dNTP concentrations are relatively low, and that the dNTP-DPase activity can deplete dNTPs and interfere with DNA polymerization Thus, we have discovered for the first time that in the presence of RNA, DNA polymerase can behave as a diphosphatase and inhibit DNA synthesis when dNTP quantity is low. These in vitro observations might imply a plausible role of RNA in vivo, such as suppressing DNA synthesis during a resting phase （Go） of the cell cycle, when RNA quantity is high and dNTP quantity is low.

Tuning the molecular size of site-specific interferon-polymer conjugate for optimized antitumor efficacy

The covalent attachment of protein-resistant polymers to therapeutic proteins is a widely used method for extending their in vivo half-lives; however, the effect of molecular weight of polymer on the in vitro and in vivo functions of protein-polymer conjugates has not been well elucidated. Herein we report the effect of molecular weight of poly（oligo（ethylene glycol） methyl ether methacrylate） （POEGMA） on the in vitro and in vivo properties of C-termi- nal interferon-alpha （IFN）-POEGMA conjugates. Increasing the molecular weight of POEGMA decreased the in vitro activity of IFN-ct but increased its thermal stability and in vivo pharmacokinetics. Intriguingly, the in vivo antitumor efficacy of IFN-a was increased by increasing the POEGMA molecular weight from ca. 20 to 60 kDa, but was not further increased by increasing the molecular weight of POEGMA from ca. 60 to 100 kDa due to the neutralization of the improved pharmacokinetics and the reduced in vitro activity. This finding offers a new viewpoint on the molecular size rationale for designing next-generation protein-polymer conjugates, which may benefit patients by reducing admin- istration frequency and adverse reactions, and improving therapeutic efficacy.