Intrinsic host restriction factors of human cytomegalovirus replication and mechanisms of viral escape

Before a pathogen even enters a cell, intrinsic immune defenses are active. This first-line defense is mediated by a variety of constitutively expressed cell proteins collectively termed "restriction factors"(RFs), and they form a vital element of the immune response to virus infections. Over time, however, viruses have evolved in a variety ways so that they are able to overcome these RF defenses via mechanisms that are specific for each virus. This review provides a summary of the universal characteristics of RFs, and goes on to focus on the strategies employed by some of the most important RFs in their attempt to control human cytomegalovirus(HCMV) infection. This is followed by a discussion of the counter-restriction mechanisms evolved by viruses to circumvent the host cell's intrinsic immune defenses. RFs include nuclear proteins IFN-γ inducible protein 16(IFI16)(a Pyrin/HIN domain protein), Sp100, promyelocytic leukemia, and h Daxx; the latter three being the keys elements of nuclear domain 10(ND10). IFI16 inhibits the synthesis of virus DNA by downregulating UL54 transcription- a gene encoding a CMV DNA polymerase; in response, the virus antagonizes IFI16 via a process involving viral proteins UL97 and pp65(p UL83), which results in the mislocalizing of IFI16 into the cytoplasm. In contrast, viral regulatory proteins, including pp71 and IE1, seek to modify or disrupt the ND10 proteins and thus block or reverse their inhibitory effects upon virus replication. All in all, detailed knowledge of these HCMV counter-restriction mechanisms will be fundamental for the future development of new strategies for combating HCMV infection and for identifying novel therapeutic agents.

Dynamic changes of telomeric restriction fragment (TRF) lengths in cells during the developmental process from embryos to seedlings and a comparison with the embryonal calli in Ginkgo biloba L.

Telomeres are the structures that locate at the terminals of linear eukaryotic chromosomes. They can play essential roles in many cellular processes. The terminal location ofArabidopsis-type TTTAGGG tandem repeats were thought to be highly conserved. The terminal location of Ginkgo biloba L. consisting of TTTAGGG tandem repeats, were confirmed by Bal31 exonuclease degradation and Southern blotting. By comparing telomeric restriction fragment （TRF） lengths at different developmental stages from embryos to seedlings, a fluctuant tendency towards variation was found in these samples. The TRF length of embryos was also compared with that of embryonal calli and an upward trend was discovered in callus culture. The results suggest that there should be a telomerase mechanism or/and ALT mechanism for the maintenance of telomere length.

Research on Impact Mechanism and Power System of Urbanization in West China

Based on the current situation of urbanization development in West China, this paper analyses main factors responsible for sluggish urbanization in West China as follows: impact of environment factor, impact of population quality and quantity, lagging of public product service, stagnancy of technological development, backwardness of slow growth, and rigidity of system building. And then this paper analyses the restriction mechanism of urbanization in West China: at the superficial level, the constraints of urbanization in West China arise from the shortage of capital; at the profound level, the backward culture contributes to the constraints of urbanization in West China. The thread of resolving restriction mechanism of urbanization in West China is put forward from system, economy and culture. On the basis of this thread, we construct the power system for the development of urbanization in West China. The power system for urbanization in West China should be propelled by "four forces", namely, pull of external forces, cohesive strength of regional market environment, expansion power inside countryside, traction of industrial structure adjustment. Innovation is the engine of impetus for urbanization in West China; spatial clustering and modernization of industry is the major driving force for urbanization; the government behaviour, driving of foreign investment, great projects and other forces are supplementary power. Via the main power, we should take the market as medium to achieve the role of power in promoting urbanization.

Solidification microstructures and mechanism of grain refinement of electrolytic low titanium Al alloys

The solidification microstructures and the mechanism of grain refinement of electrolytic low titanium Al alloys were investigated by means of the wedge-shaped sample, the directional solidification and the rapid solidification ribbon. The results show that the coarse columnar grains formed in pure Al are transformed into the equiaxed grains in electrolytic low titanium Al alloys. The grain refinement is resulted from the constitutional supercooling caused by Ti and heterogeneous nucleation of Al3Ti particles. Under the condition of normal cooling rate, the grains are refined by the increment of constitutional supercooling when the content of titanium is less than 0.2%. With the increment of content of titanium, the grains are mainly refined by heterogeneous nucleation of Al3Ti particles. The grain size is decreased with the increment of cooling rate. When the cooling rate is larger than 105℃/s, the grain size is decreased to 0.1-10μm, the grain refinement is resulted from the larger cooling velocities mainly. After directional solidification, the equiaxed grains can be formed and the Ti element is distributed at the center of the grains.

内蒙古筑牢我国北方重要生态安全屏障的现实基础、制约因素与机制构建

筑牢我国北方重要生态安全屏障是内蒙古肩负的重大责任。从建设历程看,内蒙古筑牢生态安全屏障经历了反复调试、稳健推进和释放能量的演进历程。从建设成效看,以林草修复为基础的生态环境改善效果显著,制度体系保障机制逐渐完善,多维度治理创新和数智技术运用初见成效,产业和能源结构日趋升级。但生态理性缺失、生态要素结构失衡、传统产业绿色化转型缓慢、环保大数据共享不足等仍制约着生态安全屏障建设。因此,要树立大生态观,以多维度协同治理模式为先导、以治理主体耦合运行机制为主线、以生产生活绿色化为载体、以遵循自然规律的生态技术为驱动、以代内与代际并重的监管机制为补充是筑牢我国北方重要生态安全屏障的践行之路。

血流限制训练干预老年肌少症:生物学机制和应用方案建议

背景:肌少症是一种慢性病,会导致力量丧失和功能下降,增加老年人虚弱、残疾、跌倒和死亡风险。血流限制训练可以有效治疗肌少症,但还缺乏对其优缺点、生物学机制和应用方案的全面回顾。目的:通过回顾血流限制训练干预肌少症的优势、局限性和生物学机制,并基于当前已发表的证据给予应用方案建议。方法:检索各大数据库建库至2023年2月发表的文献。英文检索词:blood flow restriction training、KAATSU、elderly、sarcopenia、muscle等;中文检索词:血流限制训练、加压训练、老年人、肌少症和肌肉等。对纳入的82篇文献进行整理和分析。结果与结论:①血流限制训练作为干预肌少症的一种方法,在外周肌群中有一定的效果,但其应用范围存在局限性,血流限制训练具备较高的可操作性和安全性,并能够提高肌肉力量和身体表现,但血流限制训练亦存在潜在风险,尤其证据报告了其对骨骼肌、心血管和内皮细胞等的不良事件,故需在科学指导下进行,并需进一步研究验证其对肌少症患者的效果。②血流限制训练干预肌少症的生物学机制可能包括:增加肌肉反应性充血导致肌肉肥大、改善肌肉蛋白合成能力、诱导代谢应激适应、促进骨骼肌生长和修复、激活血管内皮生长因子信号通路促进血管生成、促进卫星细胞增殖,但这些机制的具体作用和联合作用需要更深入的研究来确定。③血流限制训练干预肌少症主要受训练和袖带的影响,为避免出现不良事件,建议训练负荷20%-50%1RM,重复次数20-75次,训练频率每周两三次,组间间隔30-60 s,上肢训练使用较小尺寸的袖带且加压值≤140 mmHg,下肢训练使用较大尺寸的袖带且加压值≤180 mmHg,通常选择完全闭塞动脉血流压力值的50%-80%,但老年人血流限制训练频度和组间间隔的研究还需更多探讨,同时袖带加压值的最适选择亦需要进一步研究。

基于改进YOLOv5算法和DeepSort算法的多目标检测和跟踪

针对因受水面波纹、反光及目标外观特征相似而导致的游泳池中目标检测跟踪困难的问题,提出一种基于改进YOLOv5算法和DeepSort算法的多目标检测和跟踪方法;通过引入注意力机制改进YOLOv5算法,增强算法对目标特征的提取能力;将检测结果输入到DeepSort算法中,在级联匹配中引入K邻域限制筛选目标检测框,减少因目标外观特征不明显引起的身份切换问题;利用匈牙利算法对检测框和预测框进行匹配,对未匹配成功的检测框采用距离交并比代替交并比进行二次匹配,提高DeepSort算法的跟踪性能;通过对比实验和消融实验验证所提出的多目标检测跟踪算法的性能。结果表明:改进的YOLOv5算法平均精准度提高2%,结合DeepSort算法跟踪检测,身份切换平均减少58次,多目标跟踪精确率为80.26%,比原始YOLOv5算法和Deepsort算法跟踪准确率提升了3.85%。

欧盟碳边境调节机制的贸易属性与中国的对策

欧盟碳边境调节机制要求进口商根据特定进口产品的碳含量与欧盟碳排放交易市场的配额价格购买并提交相应的排放配额,由此支付特殊的碳成本,从而对国际货物贸易造成了限制性影响。就其贸易属性而言,它不属于关税措施,也不构成在进口环节加征的国内税费,而是一项具有数量限制效果的进口措施。为应对欧盟碳边境调节机制,防范跨境单边气候措施的使用,中国应深刻揭露其贸易保护主义特质,积极开展中欧合作应对气候变化,努力构建绿色低碳贸易规则体系,加快完善国内碳市场的建设。

预算部门绩效自评价质量提升制约因素与驱动机制研究——基于2017—2020年度中央部门绩效自评结果分析

绩效自评价作为绩效评价的重要形式,在预算部门履职尽责的自我识别和诊断过程中发挥着关键作用,高质量自评结果的输出为部门优化资源分配结构、改进预算管理提供了重要参考依据。为此,文章基于2017—2020年中央部门决算报告公开的绩效自评价结果信息,梳理、分析绩效自评价在中央部门的实施现状、实践困境及影响自评价质量的制约因素,以预算部门绩效自评价结果质量提升为着力点,尝试从责任传导机制、激励约束机制、内部管理机制、技术保障机制四个方面设计由内及外的预算绩效质量提升驱动机制,以期为预算部门绩效自评价及绩效管理质量提升提供理论支撑与实践指导。

不同运动方式促进周围神经损伤后的功能恢复

背景:运动作为一种主动康复的方式可以改善周围神经损伤导致的功能障碍,而不同运动方式针对的病变部位及恢复机制不同。目的:综合分析不同运动方式在周围神经损伤功能恢复中的应用及机制。方法:应用计算机检索中国知网、PubMed数据库建库时间至2024年1月期间的相关文献,英文检索词为“peripheral nerves injury,spinal cord,exercise,cerebral cortex,muscle atrophy,mirror therapy,blood flow restriction training”,中文检索词为“周围神经损伤,脊髓,大脑皮质,肌肉萎缩,有氧运动,血流限制,镜像运动”,最终纳入77篇文献进行分析。结果与结论:周围神经损伤后会引起其支配骨骼肌萎缩、相应脊髓节段病变、感觉运动皮质重塑等系统性的病理变化。有氧运动可以加强免疫反应,促进神经胶质细胞极化以及神经生长因子的释放,改善功能障碍。血流限制运动可以调节肌肉生长因子的分泌,促进肌肉生长及增强肌肉力量。镜像运动在激活大脑皮质、减少皮质重塑方面有良好的作用。不同运动方式在周围神经损伤功能恢复中具有潜在的益处,然而目前仍存在一些问题和挑战,例如运动方式的选择、运动强度和频率的控制及机制的详细解析等。

基于改进注意力机制的自然语言特征提取仿真

自然语言具有模糊性和歧义性特点,加大了特征提取难度,为了能够精准提取自然语言特征,提出一种基于模糊关联优化的自然语言特征提取方法。将不确定性自然语言信息利用三元语言表示模型描述,给出一个初始隶属度函数(MF),设定最大化模糊项集支持度和语义可解释性为适应度函数,利用群搜索优化(GSO)算法获取最佳MF,通过优化后的模糊关联规则算法挖掘自然语言信息。在注意力机制中加入生成函数和限制函数,改进传统注意力机制,基于改进后的注意力机制完成自然语言特征提取。仿真结果表明,所提方法可以获取高精度与高覆盖率的自然语言特征提取结果。

新时代加强对“一把手”监督的研究述评

高度重视“一把手”监督工作是新时代加强党和国家监督的内在需要。党的十八大以来,我国“一把手”监督工作实现了新发展,相应的理论研究也取得了新成果。从现有文献看,加强对“一把手”监督的内在机理在于“一把手”的特殊地位以及实践中存在的监督难题,监督思想源自无产阶级政党的权力监督与制约理论,监督困境体现在监督主体和客体双重层面,监督困境的原因在于权力分配不科学、监督机制不完善、文化支撑不足等。实践中,要提升对“一把手”监督的效能,需从调整“一把手”权力结构、加强监督文化建设、完善运行机制等方面推进,进一步细化聚焦研究议题、拓宽研究领域、深化理论研究。

血流限制训练运动表现效果及作用机制研究进展

本文主要运用文献资料法、归纳总结法等研究方法,对血流限制训练(BFRT)在运动表现效果及作用机制方面的成果进行综述与分析,探讨BFRT现阶段的研究进展。结果显示,BFRT能显著增加肌肉质量与力量、改善有氧代谢能力、提高运动表现成绩,并对康复治疗效果有积极影响,但BFRT的具体作用机制仍不明确,可能涉及代谢激素、信号通路、血管生长因子和肌纤维募集等方面因素。鉴于此,在未来的研究中应注重不同个体之间的差异,在确保安全性的前提下,进一步探索BFRT的作用机制和最佳训练方案,以期为运动训练和康复治疗等方面提供新的路径。

基于应用场景的丘陵山区农业机械化发展路径研究

中国丘陵山地耕地面积、农作物播种面积分别占全国34.62%、34.20%,覆盖人口达54.2%,GDP仅占全国的30%,整体农业机械化水平未达50%,研究如何加快推进丘陵山区农业机械化是建设农业强国的迫切需求。本研究以我国耕作制度区划为基础,结合丘陵山区分布等因素开展丘陵山区农业机械化区划;以各地区资源禀赋条件、经济社会情况、产业经济效益为基础,梳理我国丘陵山区农业机械化发展现状,从丘陵山区耕地条件、土壤和农艺等方面分析我国丘陵山区农机应用特殊场景,结合农机研发制造和推广应用等因素分析我国丘陵山区农业机械化发展的瓶颈;围绕丘陵山区应用场景探讨提出紧凑型轻量化的专用发动机、轻量化及减黏降阻的先进材料、轻简化的整机结构设计等十大农机共性技术需求以及黏重土壤的高效低耗耕整地装备、缓坡地黏重土壤的大宗粮油糖和高山蔬菜播种装备、缓坡地黏重土壤的油菜和高山蔬菜移栽装备等十大农机适用装备需求;借鉴日本、韩国等丘陵山区农业机械化发展经验,从良机—良种—良法—良田—良制深入融合和研产推用四位一体化的角度提出系统推进丘陵山区机械化的思路与举措,以促进丘陵山区农业机械化高质量发展。

Restriction of Intramolecular Motion(RIM):Investigating AIE Mechanism from Experimental and Theoretical Studies

Mechanistic studies promote scientific development from phenomena to theories.Aggregation-induced emission(AIE),as an unusual photophysical phenomenon,builds the bridge between molecular science and aggregate mesoscience.With the twenty-year development of AIE,restriction of intramolecular motion(RIM)has been verified as the working mechanism of AIE effect.In this review,these mechanistic works about RIM are summarized from experimental and theoretical perspectives.Thereinto,the experimental studies are introduced from three parts:external rigidification,structural modification and structural characterization.In the theoretical part,calculations on the low-frequency motion of AIEgens have been performed to prove the RIM mechanism.By virtue of the theoretical calculations,some new mechanisms are proposed to supplement the RIM,such as restriction of access to conical intersection,suppression of Kasha transition,restriction of access to dark state,etc.It is foreseeable that the RIM mechanism will unify the photophysical theories for both molecules and aggregates,and inspire more progress in aggregate science.

Molecular mechanism of the inhibitory effect of methylation outside the recognition sequence of restriction endonuclease Pvu Π on its cleavage activity

In 1991, we found that methylation outside the PvuⅡ recognition sequence could partially inhibit its cleavage activity. To clarify the molecular mechanism, three plasmids with different methylation states were constructed. Then, together with the original one, four plasmids were digested with different amounts of PvuⅡ. Results show that methylation on both sites results in 90% inhibition; moving the methylated site one base further away decreases the inhibitory effect to about 30%; with the adjacent dam methylation site eliminated, the inhibitory effect disappears. The data suggest that the inhibition of cleavage activity caused by outside methylation is not "all or none", and the degree of inhibition is dependent on the position and the number of methylated bases.

A New Critical Value Concerning the Genealogy of Long Period Families at L_4 in the Restricted Three-body Problem

We found another critical mass ratio value -↑μ between μ4 and μ5 concerning the genealogy of the long period family around the equilateral equilibrium point L4 in the restricted three-body problem. This value has not been pointed out before. We used numerical computations to show how the long period family evolves around this critical value. The case is similar to that of the critical values between μ2 and μ4, with slight difference in evolution details.

大地线航法在智能船舶上的应用

沿最短路径航行是建立高效和清洁航运的手段之一。大地线(又称测地线)是空间曲面上两点之间的最短路径。由于在地球椭圆体上采用大地线航法计算复杂、且航向不定,加之与恒向线相比,平均航程仅缩短了5%,导致大地线航法几乎无法应用于传统航海实践中。利用智能船舶的计算、数据获取、航向控制等能力,能最大限度地利用大地线航法路径最短这个优点。本文首先采用了一种快速且高精度的大地线正反解算法,其计算时间为微秒级;其次,利用智能船舶当前实时位置动态及终点计算所需大地线航向,并将新航向指令发送给自动舵。最后,提出不同策略下的航向变更限制机制(ACRM),避免频繁转向以降低自动舵的工作负荷。仿真结果表明,ACRM有助于在最短航程与最少转向次数之间取得平衡。

初始应力状态对侧限条件黏土动态压缩过程和力学性能的影响

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