Quantum Mechanics and Computation

In quantum computation non classical features such as superposition states and entanglement are used to solve problems in new ways, impossible on classical digital computers.We illustrate by Deutsch algorithm how a quantum computer can use superposition states to outperform any classical computer. We comment on the view of a quantum computer as a massive parallel computer and recall Amdahls law for a classical parallel computer. We argue that the view on quantum computation as a massive parallel computation disregards the presence of entanglement in a general quantum computation and the non classical way in which parallel results are combined to obtain the final output.     

E3 ubiquitin ligase that recognizes sugar chains

N-glycosylation of proteins in the endoplasmic reticulum (ER) has a central role in protein quality control. Here we report that N-glycan serves as a signal for degradation by the Skp1-Cullin1-Fbx2-Roc1 (SCF(Fbx2)) ubiquitin ligase complex. The F-box protein Fbx2 (ref. 4) binds specifically to proteins attached to N-linked high-mannose oligosaccharides and subsequently contributes to ubiquitination of N-glycosylated proteins. Pre-integrin beta 1 is a target of Fbx2; these two proteins interact in the cytosol after inhibition of the proteasome. In addition, expression of the mutant Fbx2 Delta F, which lacks the F-box domain that is essential for forming the SCF complex, appreciably blocks degradation of typical substrates of the ER-associated degradation pathway. Our results indicate that SCF(Fbx2) ubiquitinates N-glycosylated proteins that are translocated from the ER to the cytosol by the quality control mechanism.     

Rutile U-Pb age for the ultrahigh pressure eclogite from the Dabie Mountains,central China: Evidence for rapid cooling

The U-Pb isotope compositions of rutile, omphacite and garnet in the eclogite from the Jinheqiao area in the Southern Dabie ultrahigh-pressure metamorphic zone were analyzed. The consistent high precision U-Pb age (218 ± 1.2) Ma of rutile in eclogite from the Dabie Mountains was obtained by two ways of isochron and common Pb correction based on the composition of omphacite. This proves that the omphacite in eclogite has a U/Pb ratio (m = 2.8) low enough to be used for common Pb correction in the analyses of rutile. Under the rapid cooling condition (40℃/Ma) the closure temperature for U-Pb diffusion in rutile is about 470℃. Thus, this U-Pb age of rutile proves that 218 Ma should be the cooling age of eclogite at 470℃ instead of the peak metamorphic age.     

Mutations in Rab3a alter circadian period and homeostatic response to sleep loss in the mouse

Rab3a is the most abundant Rab (ras-associated binding) protein in the brain and has a regulatory role in synaptic vesicle trafficking. Mice with a targeted loss-of-function mutation in Rab3a have defects in Ca(2+)-dependent synaptic transmission: the number of vesicles released in response to an action potential is greater than in wildtype mice, resulting in greater synaptic depression and the abolishment of CA3 mossy-fiber long term potentiation. The effect of these changes on behavior is unknown. In a screen for mouse mutants with abnormal rest-activity and sleep patterns, we identified a semidominant mutation, called earlybird, that shortens the circadian period of locomotor activity. Sequence analysis of Rab3a identified a point mutation in the conserved amino acid (Asp77Gly) within the GTP-binding domain of this protein in earlybird mutants, resulting in significantly reduced levels of Rab3a protein. Phenotypic assessment of earlybird mice and a null allele of Rab3a revealed anomalies in circadian period and sleep homeostasis, providing evidence that Rab3a-mediated synaptic transmission is involved in these behaviors.     

基于MATLAB的信号与系统软件实验平台

基于MATLAB软件的信号与系统实验平台,弥补了教学中的不足,通过实验,加强学生对信号与系统课程的理解和掌握。     

cDNA cloning and functional analysis of 4-coumarate --CoA: ligase (4CL) gene in Chinese white aspen

cDNA encoding 4-coumarate: CoA ligase (4CL) was isolated from the secondary developing xylem of Chinese white aspen (Populus tomentosa) by RT-PCR for the first time, which was 1619 bp in length. The coding sequence and putative amino acid sequence showed 97.53% and 97.00% identity to that of Pt4CL1 in quaking aspen (P. tremuloids), respectively. Molecular analysis indicated that 4CL was encoded by multiple genes in P.tomentosa, its mRNA was highly accumulated in xylem and the expression of 4CL revealed a biphasic pattern in one growing season, almost in phase with the expression of other related enzymes in lignin biosynthesis. Transgenic research showed that expression of antisense 4CL cDNA led to the decreasing of lignin content in transgenic tobaccos, among which the average reduction was 10.3% and the highest could be up to 18.9%. These data suggested that 4CL gene was a potential gene used in altering lignin biosynthesis by biotechnology for producing new materials of papermaking.     

Evidence for gene transfer and expression of factor IX in haemophilia B patients treated with an AAV vector

Pre-clinical studies in mice and haemophilic dogs have shown that introduction of an adeno-associated viral (AAV) vector encoding blood coagulation factor IX (FIX) into skeletal muscle results in sustained expression of F.IX at levels sufficient to correct the haemophilic phenotype. On the basis of these data and additional pre-clinical studies demonstrating an absence of vector-related toxicity, we initiated a clinical study of intramuscular injection of an AAV vector expressing human F.IX in adults with severe haemophilia B. The study has a dose-escalation design, and all patients have now been enrolled in the initial dose cohort (2 x 10(11) vg/kg). Assessment in the first three patients of safety and gene transfer and expression show no evidence of germline transmission of vector sequences or formation of inhibitory antibodies against F.IX. We found that the vector sequences are present in muscle by PCR and Southern-blot analyses of muscle biopsies and we demonstrated expression of F.IX by immunohistochemistry. We observed modest changes in clinical endpoints including circulating levels of F.IX and frequency of FIX protein infusion. The evidence of gene expression at low doses of vector suggests that dose calculations based on animal data may have overestimated the amount of vector required to achieve therapeutic levels in humans, and that the approach offers the possibility of converting severe haemophilia B to a milder form of the disease.     

大跨度拱桥的非线性与稳定分析

考虑施工过程中结构体系不断变化、荷载逐步增加以及拱桥结构大位移等因素,建立了大跨度拱桥结构的非线性稳定计算模型,编制了相应的程序。文中对某拱桥施工全过程的稳定性和几何非线性模拟计算,得出了各个施工阶段稳定安全和非线性影响系数;计算结果为该大桥设计和施工提供了理论依据。     

新型苯并呋喃新木脂素类化合物的合成研究

以对羟基苯甲醛和丙二酸为原料,经Knoevenagel缩合反应,酯化、仿生氧化偶联、DDQ脱氢、还原和水解等反应步骤,合成了6种未见文献报道的苯并二氢呋喃新木脂素和苯并呋喃新木脂素类化合物(1~6).其中两分子对羟基苯丙烯酸甲酯仿生氧化偶联为它的二聚体(1)和DDQ脱氢反应是整个合成路线的关键步骤.DDQ脱氢反应可成功实现由苯二氢呋喃向苯并呋喃环转化,这为合成苯并呋喃新木脂素类化合物提供了一种新方法.