基于椭圆曲线的代理多签名方案的安全性分析

在一个安全的代理签名方案中，只有指定的代理签名人能够代表原始签名人生成代理签名．基于椭圆曲线离散对数问题，纪家慧和李大兴提出了一个代理签名方案和一个代理多签名方案，陈泽雄等人给出了另外两个代理多签名方案．但是，在他们的方案中，原始签名人能够伪造代理签名私钥．为了抵抗原始签名人的伪造攻击，改进了代理签名密钥的生成过程，并对改进的方案进行了安全性分析．

Simultaneous multiwavelength observations of sagittarius A

We observed Sgr A* using the Very Large Array (VLA) and the Giant Metrewave Radio Telescope (GMRT) at multiple centimeter and millimeter wavelengths on 2003 June 17. The measured flux densities of Sgr A*, together with those obtained from the Submillimeter Array (SMA) and the Keck II 10 m telescope on the same date, are used to construct a simultaneous spectrum of Sgr A* from 90 cm to 3.8 mu m. The simultaneous spectrum shows a spectral break at about 3.6 cm, a possible signature of synchrotron self-absorption of the strong radio outburst that occurred near epoch 2003 July 17. At 90 cm, the flux density of Sgr A* is 0.22 +/- 0.06 Jy, suggesting a sharp decrease in flux density at wavelengths longer than 47 cm. The spectrum at long cm wavelengths appears to be consistent with free-free absorption by a screen of ionized gas with a cutoff similar to 100 cm. This cutoff wavelength appears to be three times longer than that of similar to 30 cm suggested by Davies, Walsh, & Booth based on observations in 1974 and 1975. Our analysis suggests that the flux densities of Sgr A* at wavelengths longer than 30 cm could be attenuated and modulated by stellar winds from massive stars close to Sgr A*.

The radio counter-jet of the QSO 3C 48

We present multi- frequency radio observational results of the quasar 3C 48. The observations were carried out with the Very Large Array ( VLA) at five frequencies, 0.33, 1.5, 4.8, 8.4, and 22.5 GHz, and with the Multi- Element Radio Linked Interferometer Network ( MERLIN) at the two frequencies of 1.6 and 5 GHz. The source shows a one- sided jet to the north within 1", which then extends to the northeast and becomes diffuse. Two bright components ( N2 and N3), containing most of the flux density, are present in the northern jet. The spectral index of the two components is alpha(N2) similar to -0.99 +/- 0.12 and alpha(N3) similar to - 0.84 +/- 0.23 ( S proportional to nu(alpha)). Our images show the presence of an extended structure surrounding component N2, suggestive of strong interaction between the jet and the interstellar medium ( ISM) of the host galaxy. A steep- spectrum component, labelled S, located 0.25 " southwest to the flat- spectrum component which could be the core of 3C 48, is detected at a significance of > 15 sigma. Both the location and the steepness of the spectrum of component S suggest the presence of a counter- jet in 3C 48.

Bending of jets in the QSO NRAO 530

We present radio images of NRAO 530 on scales ranging from pc to kpc. The observations include the EVN at 5 GHz, the VLBA at 1.6, 8.6 and 15 GHz, the MERLIN at 1.6 and 5 GHz, and the VLA at 5, 8.4, 15, 22, and 43 GHz. The VLBI images show a core-jet structure with an oscillating trajectory on a scale of about 30 mas north of the strongest compact component (core). Superluminal motions are detected in five of the jet components with apparent velocities in the range of 13.6 to 25.2c. A new component is detected at 15 GHz with the VLBA observations, which appears to be associated with the outburst in 2002. Significant polarized emission is detected around the core with the VLBA observations at 15 GHz. Rapid variations of the polarization intensity and angle are found between the epochs in 2002 and 2004. On the kpc-scale, a distant component (labelled as WL) located 11 aresec west (PA=-86 degrees) of the core is detected beyond the core-jet structure which extended to several hundreds of mas in the north-west direction (-50 degrees). A significant emission between the core-jet structure and the WL is revealed. A clump of diffuse emission (labelled EL, 12 arcsec long) at PA 70 degrees to the core, is also detected in the VLA observations, suggesting the presence of double lobes in the source. The core component shows a flat spectrum, while the distant components WL and EL have steep spectra. The steep spectra of the distant components and the detection of the arched emission suggest that the distant components are lobes or hot-spots powered by the core of NRAO 530. The morphologies from pc- to kpc-scales and the bending of jets are investigated. The observed radio morphology from pc to kcp appears to favor the model in which precession or wobbling of the nuclear disk drives the helical motion of the radio plasma and produces the S-shaped structure on kpc scale.

高产抗旱优质谷子新品种辐谷7号的选育与推广利

利用400Gy 60Co γ射线处理87070谷子品系干种子,选育出辐谷7号新品种。该品种具有株型紧凑、茎秆矮、高产抗旱优质并且适应种植地区广等特点。2002年2月通过陕西省农作物品种审定委员会审定,截止2008年在黄土高原地区累计推广10.8万hm2。

簇毛麦（ Dasypyrum villosum）矮秆突变体的研究

株高是农作物的重要农艺性状之一，适度矮化有利于农作物的耐肥、抗倒、高产等。20世纪50年代，以日本的赤小麦为矮源的半矮秆小麦的培育和推广，使得世界粮食产量显著增长，被誉为“绿色革命”。迄今为止，已报到的麦类矮秆、半矮秆基因已达70多个，但由于某些矮源极度矮化或者矮化的同时伴随不利的农艺性状，使得真正运用于育种实践的矮源较少。因此，发掘和鉴定新的控制麦类作物株高的基因，开展株高基因定位、克隆及作用机理等方面的研究，对实现麦类作物株高的定向改良，具有重要的理论意义和应用价值。簇毛麦(Dasypyrum villosum，2n＝14，VV)是禾本科簇毛麦属一年生二倍体异花授粉植物，为栽培小麦的近缘属。本课题组在不同来源的簇毛麦杂交后代中发现了一株自然突变产生的矮秆突变体。观察分析了该突变体的生物学特性，对矮秆性状进行了遗传分析，对茎节细胞长度、花粉的活力进行了细胞学观察，考察了该突变体内源赤霉素含量及不同浓度外施赤霉素对突变体的作用，分析了赤霉素生物合成途径中的内根贝壳杉烯氧化酶（KO）和赤霉素20氧化酶(GA20ox)的转录水平，对赤霉素20氧化酶和赤霉素3-β羟化酶(GA3ox)进行了克隆和序列分析，并对GA20ox进行了原核表达和表达的组织特异性研究。主要研究结果如下：1. 该突变体与对照植株在苗期无差异，在拔节后期才表现出植株矮小，相对对照植株，节间伸长明显受到抑制，叶鞘长度基本不变。在成熟期，对照植株的平均株高为110cm，而突变株的平均株高为32cm，仅为对照植株的1/3 左右。除了株高变矮以外，在成熟后期，突变株还表现一定程度的早衰和雄性不育。I2-KI染色法观察花粉活力结果表明，对照植株花粉90%以上都是有活力的，而突变植株的花粉仅20%左右有活力。2. 突变株与对照植株的杂交F1代均表现正常株高，表明该突变性状为隐性突变。F1代植株相互授粉得到的168株F2代植株中，株高出现分离，正常株高（株高高于80cm）与矮秆植株（株高矮于40cm）的株数比为130：38，经卡方检验，其分离比符合3：1的分离比，因此推测该突变体属于单基因的隐性突变。3. 用ELISA方法检测突变株和对照植株的幼嫩种子中内源性生物活性赤霉素（GA1＋3）含量，结果表明突变株的赤霉素含量为36 ng/ml，而对照植株的赤霉素含量为900 ng/ml。对突变株外施赤霉素，发现矮秆突变株的株高和花粉育性均可得到恢复。这些结果表明该突变株为赤霉素缺陷型突变。4. 用荧光定量PCR方法比较突变株与对照植株中内根贝壳杉烯氧化酶和赤霉素20氧化酶的转录水平，结果表明突变株的KO转录水平比对照植株分别提高了6倍（苗期）和16倍（成熟期），突变株的GA20ox转录水平与对照植株在苗期无明显差异，在成熟期突变株较对照植株则提高了10倍左右。这些结果表明该矮秆突变体与赤霉素的生物合成途径密切相关，而且极有可能在赤霉素的生物合成途径早期就发生了改变。5. 以簇毛麦总基因组为模板，同源克隆了GenBank登录号为EU142950，RT-PCR分离克隆了簇毛麦的GA3ox基因cDNA全长序列，分析结果表明该cDNA全长1206bp，含完整编码区1104bp，推测该序列编码蛋白含368个氨基酸残基，分子量为40.063KD，等电点为6.27。预测的氨基酸序列含有双加氧酶的活性结构，在酶活性中心2个Fe离子结合的氨基酸残基非常保守。该序列与小麦、大麦和水稻的GA3ox基因一致性分别为98%、96%、86%。基因组序列与cDNA序列在外显子部分一致，在478-715bp和879-1019bp处分别含238bp和140bp的内含子。6. 通过RT-PCR技术克隆了簇毛麦的GA20ox基因全长，命名为DvGA20ox，GenBank登录号为EU142949。该基因全长1080个碱基，编码359个氨基酸，具有典型的植物GA20ox基因结构。该基因编码的蛋白质与小麦、大麦、黑麦草等GA20ox蛋白的同源性分别为98%，97% 和91%。该序列重组到原核表达载体pET-32a(+)上，将获得的重组子pET-32a(+)-DvGA20ox转化大肠杆菌BL21pLysS后用IPTG进行诱导表达。SDS-PAGE分析表明，DvGA20ox基因在大肠杆菌中获得了高效表达，融合蛋白分子量为55kDa。定量PCR分析表明，该基因在簇毛麦不同器官中的表达差异明显：叶片中表达水平最高，根部表达水平次之，茎部和穗中表达较弱。在外施赤霉素后，该基因的表达水平在两小时以后急剧下降，表明该基因的表达受自身的反馈调节。本研究结果认为，(1)该簇毛麦矮秆突变体为单基因的隐性突变；(2)该矮秆突变体为赤霉素敏感突变，内源赤霉素含量检测表明突变体的内源性赤霉素含量仅为对照植株的1/30；(3)荧光定量PCR结果表明突变株的赤霉素生物合成途径的关键酶基因表达水平比对照植株高，而且突变植株的赤霉素生物合成改变很可能发生在赤霉素生物合成途径的早期；(4)GA20ox有表达的组织特异性，且受到自身产物的反馈调节。 Plant height is an impotrant agronomic trait of triticeae crops.Semi-dwarf cropcultivars, including those of wheat, maize and rice, have significantly increased grainproduction that has been known as “green revolution”. The new dwarf varieties couldraise the harvest Index at the expense of straw biomass, and, at the sametime, improvelodging resistance and responsiveness to nitrogen fertilizer. Moreover, dwarf traits ofplant are crucial for elucidating mechanisms for plant growth and development aswell. In many plant species, various dwarf mutants have been isolated and theirmodles of inheritance and physiology also have been widely investigated.The causesfor their dwarf phenotypes were found to be associated with plant hormones,especially, gibberellins GAs.Dasypyrum villosum Candargy (syn.Haynaldia villosa) is a cross-pollinating,diploid (2n = 2x = 14) annual species that belongs to the tribe Triticeae. It is native toSouthern Europe and West Asia, especially the Caucasuses, and grows underconditions unfavorable to most cultivated crops. The genome of D. villosum,designated V by Sears, is considered an important donor of genes to wheat for improving powdery mildew resistance, take-all, eyespot, and plant and seed storageprotein content. A spontaneous dwarf mutant was found in D. villosum populations.The biological character and modles of inheritance of this dwarf mutant are studied.The cell length of stem cell is observed. The influence of extraneous gibberellin tothe dwarf mutant is also examined; the transcript level of key enzyme of gibberellinbiosynthesis pathway in mutant and control plants is compared. GA3ox and GA20oxare cloned and its expression pattern is researched.1. The dwarf mutant showed no difference with control plants at seedlingstage.At mature stage, the average height of control plants were 110cm and the dwarfplants were 33cm. The height of the mutant plant was only one third of the normalplants due to the shortened internodes. Cytology observation showed that theelongation of stem epidermal and the parenchyma cells were reduced. The dwarfmutant also shows partly male sterile. Pollen viability test indicates that more than80% of the pollen of the mutant is not viable.2. The inheritance modle of this dwarf mutant is studied. All The F1 plantsshowed normal phenotype indicating that the dwarfism is controlled by recessivealleles. Among the 168 F2 plants, there are 130 normal plants and 30 dwarf plants, thesegregation proportion accord with Mendel’s 3:1 segregation. We therefore proposethat this dwarf phenotype is controlled by a single recessive gene.3. Quantitative analyses of endogenous GA1+3 in the young seeds indicated thatthe content of GA1+3 was 36ng/ml in mutant plants and 900ng/ml in normal plants.The endogenous bioactive GA1+3 in mutant plants are only about 1/30 of that innormal plants. In addition, exogenously supplied GA3 could considerably restore themutant plant to normal phenotype. These results showed that this mutant wasdefective in the GA biosynthesis.4. More than ten enzymes are involved in GA biosynthesis. KO catalyzes thefirst cytochrome P450-mediated step in the gibberellin biosynthetic pathway and themutant of KO lead to a gibberellin-responsive dwarf mutant. GA20ox catalyze therate-limited steps so that their transcript level will influence the endogenous GAbiosynthesis and modifies plant architecture. The relative expression levels of genesencoding KO and GA20ox were quantified by real time PCR to assess whether thechanges in GA content correlated with the expression of GA metabolism genes andwhere the mutant occurred during the GA biosynthesis pathway. In mutant plants,the transcript levels of KO increased about 6-fold and 16-fold at the seedling stage and elongating stage respectively comparing with the normal plants. For theseedlings, there was no notable difference in the expression of GA20ox betweenmutant and normal plants. At the elongating stage, GA20ox transcript increased 10times in mutant plants, suggesting that the GA biosynthesis pathway in mutant plantshad changed from the early steps rather than the late steps.5. A full length cDNA of D. villosum gibberellin 3β-hydroxylase homology(designated as DvGA3ox) was isolated and consisted of 1206bp containing an openreading frame of 1104bp encoding 368 predicted amino acid residues. Identityanalysis showed that the gibberellin 3β-hydroxylase nucleotide sequence shared 98%,96% and 86% homology with that of wheat, barley and rice. The predicted peptidecontained the active-site Fe of known gibberellin 3β-hydroxylase and the regionhomologous to wheat, barley and Arabidopsis. The genomic clone of gibberellin3β-hydroxylase has two introns.6. The full-length cDNA of D. villosum gibberellin 20 oxidase (designated asDvGA20ox) was isolated and consisted of 1080-bp and encoded 359 amino acidresidues with a calculated mol wt of 42.46 KD. Comparative and bio-informaticsanalyses revealed that DvGA20ox had close similarity with GA20ox from otherspecies and contained a conserved LPWKET and NYYPXCQKP regions. Tissueexpression pattern analysis revealed DvGA20ox expressed in all the tissues that wereexamined and the highest expression of DvGA20ox in expanding leaves followed byroots. Heterologous expression of this cDNA clone in Escherichia coli gave a fusionprotein that about 55KD. Transcript levels of DvGA20ox dramatically reduced twohours after application of biologically active GA3, suggesting that the biosynthesis ofthis enzymes might be under feedback control.

RNAi沉默烟草GA 20-氧化酶基因研究

赤霉素是一种高效能的广谱植物生长调节剂，为五大植物激素之一，具有重要的生物学功能。目前利用赤霉素突变体研究生物合成途径和信号转导已经成为热点。 GA 20-氧化酶是GA生物合成中的一类关键酶，它位于GA合成途径的中心位置。本研究根据烟草（Nicotiana tabacum）GA 20-氧化酶基因序列，设计2对分别含有特定酶切位点的特异引物，以烟草基因组DNA为模板，扩增目的基因(约250 bp)片段。将正、反向目的片段分别插入中间载体的内含子两侧，再经BamH I和Sac I双酶切回收约700 bp的目的片段，插入到双元载体质粒p2355中，成功构建了含GA 20-氧化酶基因片段反向重复序列的植物表达载体p23700。分别将p2355质粒和p23700质粒导入根癌农杆菌（Agrobacterium tumefaciens）EHA105中并转化烟草叶片细胞，经卡那霉素选择培养，PCR及GUS组织染色鉴定，获得转基因烟草植株。以EHA105-p2355转化的烟草，获得41株转基因植株，均没有矮化表型；而以EHA105-p23700转化的烟草，获得转基因植株14株，其中具有矮化表型的烟草10株，表明反向重复序列转录产物能形成发夹RNA(hpRNA)，产生小分子干扰RNA（small interferring RNA，简称siRNA），干扰目的基因的表达。 赤霉素含量测定表明矮化植株中赤霉素合成途径的最终产物GA3总含量明显低于野生型烟草植株。荧光定量PCR结果表明，矮化转基因烟草的GA 20-氧化酶基因表达量受到明显抑制，表达量明显低于野生型对照。同时对上游内根-贝壳杉合成酶（Ent-kaurene synthase，KS）基因，下游的GA-3β羟化酶基因进行了RT-PCR分析，结果显示上游基因的表达没有规律性变化，而下游基因表达量亦降低。上述结果表明，GA 20-氧化酶基因的表达被有效地干扰了，表达受到抑制，从而影响植株体内GA3的合成，影响植株的生长发育，导致植株矮化。并推测，GA 20-氧化酶基因受到抑制，可能影响下游基因的表达。并且通过干旱胁迫测试，发现矮化植株相对于野生型植株及不含干扰片段的转基因植株，对干旱的耐受力有了很大的提高，具有更强的耐受力。 研究结果为进一步进行相关研究奠定基础。 Gibberellin(GA) is an efficient plant growth regulator. As one of five major plant hormones, it plays an important biological function. Using GA mutant for investigating biosynthetic pathways and signal transduction has become high lights. GA 20-oxidase is a crucial enzyme involved in gibberellin biosynthesis. According to tobacco (Nicotiana tabacum) GA 20-oxidase enzyme gene sequence and based on binary vector p2355, we constructed a plant expression vector p23700, which habors an inverted repeat DNA fragment of GA 20-oxidase gene drivered by Cauliflower mosaic virus promtor (CaMV 35Sp). Binary plasmid p2355 had no inverted repeat DNA fragment of GA 20-oxidase gene. The vector p2355 and p23700 were introduced into Agrobacterium tumefaciens EHA105 and tobacco leaf transformation was conducted. After selected by kanamycin and characterized by PCR and GUS hischemical reaction, transsgenic plants were obtained. Fourtheen transgenic plants, which were transformed by EHA105-p23700, were obtained. Among them, 10 were dwarf mutants. However, 41 transgenic plants with the same normal phenotype as wild type,which were transformed by EHA105-p2355, were obtained. Analysis of Gibberellin contents showed that it was lower in dwarf mutants than in normal phenotype plants. Moreover, comparing to normal phenotype plants including wild type and transgenic plants with no interference fragment, the drought tolerance of dwarf plants have greatly increased. And their proline content increased obviously after drought test. Fluorescence quantitative real time PCR (RT-PCR) showed that GA 20-oxidase gene expression was significantly inhibited in dwarf transgenic tobacco. Meanwhile, the expression of the upstream gene ent-kaurene synthase (KS) gene and downstream gene GA-3β hydroxylase gene was also detected by RT-PCR. The results presented that KS gene expression had no regular change while GA-3β hydroxylase gene expression reduced. It implied that inhibiting GA 20-oxidase gene probably reduce the expression of downstream genes. The results showed that the transcriptional products of the foreign inverted repeat fragment can form hairpin RNA (hpRNA) to induce RNAi. It presented that GA 20-oxidase gene expression was effectively interfered, resulting in reducing GA3 synthesis and inhibiting plant growth and development, then dwarf plants were produced. However, the dwarf plants had higher tolerance of drought.

Intrabeam scattering of heavy ions at HIRFL-CSR

Small-angle multiple intrabeam scattering (IBS) is an important effect for heavy-ion storage rings with electron cooling, because the cooling time is determined by the equilibrium between cooling and IBS process. All usually used numerical algorithms of IBS growth rate calculations are based on the model of the collisions proposed by A.Piwinski, but this result is a multidimensional integral. In this paper, the IBS growth rates are simulated for HIRFL-CSR using symmetric elliptic integral method, and compared with several available IBS code results.

The equation of state study in UU collisions at CSR, Lanzhou

The cooling storage ring, to be built at Lanzhou, will be able to deliver heavy ion beams up to uranium up to 0.52 GeV/u. It is expected to make considerable contribution to nuclear EOS study in the high net baryon-density region. With a relativistic transport model, we performed simulations for U+U collisions with different orientations. It is shown that by combining the forward neutron multiplicity and an event-wise elliptic flow selection, it is possible to identify the tip - tip and body - body head-on collisions. The effective identification of these two extreme configurations will allow us to study the EOS at the highest baryon density in the U+U collisions.

Cross-correlation between WMAP and 2MASS: non-Gaussianity induced by the SZ effect

We study the non-Gaussianity induced by the Sunyaev-Zel'dovich (SZ) effect in cosmic microwave background (CMB) fluctuation maps. If a CMB map is contaminated by the SZ effect of galaxies or galaxy clusters, the CMB maps should have similar non-Gaussian features to the galaxy and cluster fields. Using the WMAP data and 2MASS galaxy catalogue, we show that the non-Gaussianity of the 2MASS galaxies is imprinted on WMAP maps. The signature of non-Gaussianity can be seen with the fourth-order cross-correlation between the wavelet variables of the WMAP maps and 2MASS clusters. The intensity of the fourth-order non-Gaussian features is found to be consistent with the contamination of the SZ effect of 2MASS galaxies. We also show that this non-Gaussianity can not be seen by the high-order autocorrelation of the WMAP. This is because the SZ signals in the autocorrelations of the WMAP data generally are weaker than the WMAP-2MASS cross-correlations by a factor f(2), which is the ratio between the powers of the SZ-effect map and the CMB fluctuations on the scale considered. Therefore, the ratio of high-order autocorrelations of CMB maps to cross-correlations of the CMB maps and galaxy field would be effective to constrain the powers of the SZ effect on various scales.

Dynamics of pion production in heavy-ion collisions around 1A GeV energies

Within the framework of the improved isospin-dependent quantum molecular dynamics model, the dynamics of pion emission in heavy-ion collisions in the region of 1A GeV energies as a probe of nuclear symmetry energy at suprasaturation densities is investigated systematically. The total pion multiplicities and the pi(-)/pi(+) yields are calculated for selected Skyrme parameters SkP, SLy6, Ska, and SIII and also for the cases of different stiffness of symmetry energy with the parameter SLy6. The influence of Coulomb potential, symmetry energy, and in-medium pion potential on the pion production is investigated and compared to each other by analyzing the distributions of transverse momentum and longitudinal rapidity and also the excitation functions of the total pion and the pi(-)/pi(+) ratio. The directed flow, elliptic flow, and polar-angle distributions are calculated for the cases of different collision centralities and also the various stiffnesses of the symmetry energies. A comparison of the calculations with the available experimental data is performed.

Observation of charge-dependent azimuthal correlations and possible local strong parity violation in heavy-ion collisions

Parity (P)-odd domains, corresponding to nontrivial topological solutions of the QCD vacuum, might be created during relativistic heavy-ion collisions. These domains are predicted to lead to charge separation of quarks along the orbital momentum of the system created in noncentral collisions. To study this effect, we investigate a three-particle mixed-harmonics azimuthal correlator which is a P-even observable, but directly sensitive to the charge-separation effect. We report measurements of this observable using the STAR detector in Au + Au and Cu + Cu collisions at root s(NN) = 200 and 62 GeV. The results are presented as a function of collision centrality, particle separation in rapidity, and particle transverse momentum. A signal consistent with several of the theoretical expectations is detected in all four data sets. We compare our results to the predictions of existing event generators and discuss in detail possible contributions from other effects that are not related to P violation.

Identified particle production, azimuthal anisotropy, and interferometry measurements in Au plus Au collisions at root s(NN)=9.2 GeV

We present the first measurements of identified hadron production, azimuthal anisotropy, and pion interferometry from Au + Au collisions below the nominal injection energy at the BNL Relativistic Heavy-Ion Collider (RHIC) facility. The data were collected using the large acceptance solenoidal tracker at RHIC (STAR) detector at root s(NN) = 9.2 GeV from a test run of the collider in the year 2008. Midrapidity results on multiplicity density dN/dy in rapidity y, average transverse momentum < p(T)>, particle ratios, elliptic flow, and Hanbury-Brown-Twiss (HBT) radii are consistent with the corresponding results at similar root s(NN) from fixed-target experiments. Directed flow measurements are presented for both midrapidity and forward-rapidity regions. Furthermore the collision centrality dependence of identified particle dN/dy, < p(T)>, and particle ratios are discussed. These results also demonstrate that the capabilities of the STAR detector, although optimized for root s(NN) = 200 GeV, are suitable for the proposed QCD critical-point search and exploration of the QCD phase diagram at RHIC.

ECC密码算法的低功耗硬件实现研究

椭圆曲线密码算法作为高安全性的公钥密码;ECC算法的优化和软硬件实现是当前的研究热点;采用硬件实现椭圆曲线密码算法具有速度快、安全性高的特点,随着功耗分析、旁路攻击等新型分析方法的发展,密码算法硬件实现中的低功耗设计越来越重要;针对椭圆曲线密码算法的特点,主要对该算法芯片设计中的低功耗设计方法进行探讨。

Vacuum-deposited submonolayer thin films of a three-ring bent-core compound

Submonolayer thin films of a three-ring bent-core (that is, banana-shaped) compound, m-bis(4-n-octyloxystyryl)benzene (m-OSB), were prepared by the vacuum-deposition method, and their morphologies, structures, and phase behavior were investigated by atomic force microscopy (AFM) and transmission electron microscopy (TEM). The films have island shapes ranging from compact elliptic or circular patterns at low temperatures (below 40 degreesC) to branched patterns at high temperatures (above 60 degreesC). This shape evolution is contrary to the prediction based on the traditional diffusion-limited aggregation (DLA) theory. AFM observations revealed that two different mechanisms governed the film growth, in which the compact islands were formed via a dewetting-like behavior, while the branched islands diffusion-mediated. It is suggested m-OSB forms a two-dimensional, liquid crystal at the low-temperature substrate that is responsible for the unusual formation of compact islands. All of the monolayer islands are unstable and apt to transform to slender bilayer crystals at room temperature. This phase transition results from the peculiar molecular shape and packing of the bent-core molecules and is interpreted as escaping from macroscopic net polarization by the formation of an antiferroelectric alignment.