The quark-hadron transition in cosmology and astrophysics

A transition from normal hadronic matter (such as protons and neutrons) to quark-gluon matter is expected at both high temperatures and densities. In physical situations, this transition may occur in heavy ion collisions, the early universe, and in the cores of neutron stars. Astrophysics and cosmology can be greatly affected by such a phase transition. With regard to the early universe, big bang nucleosynthesis, the theory describing the primordial origin of the light elements, can be affected by inhomogeneities produced during the transition. A transition to quark matter in the interior by neutron stars further enhances our uncertainties regarding the equation of state of dense nuclear matter and neutron star properties such as the maximum mass and rotation frequencies.     

Van der waals picture of liquids, solids, and phase transformations

The van der Waals picture focuses on the differing roles of the strong short-ranged repulsive intermolecular forces and the longer ranged attractions in determining the structure and dynamics of dense fluids and solids. According to this physical picture, the attractive interactions help fix the volume of the system, but the arrangements and motions of molecules within that volume are determined primarily by the local packing and steric effects produced by the repulsive forces. This very useful approach, its limitations, and its successful application to a wide variety of static and dynamic phenomena in condensed matter systems are reviewed.     

中子星性质的模型依赖性

采用相对论平均场理论(RMFT)下的GL85,GL92,TM1和TM2等核物质参数组,研究了这些参数组对中子星的粒子数密度分布、状态方程及质量-半径关系的影响.结果表明,在不同的参数组下,超子出现的密度、顺序和种类均不同;状态方程的软硬情况也较大不同;中子星的引力质量和相应的半径有明显不同.计算结果也表明,采用GL85,TM1和TM2等参数组得到的中子星质量和半径均在脉冲星的观测数据范围内,而采用GL92参数组得到的中子星质量小于中子星质量下限1.4M⊙(M⊙=1.99×1030kg为太阳质量).     

密度依赖口袋常数下奇异夸克物质及奇异星

在有效质量口袋模型(EMBM)下采用密度依赖口袋常数描述奇异夸克物质,研究了口袋常数的密度依赖性对奇异夸克物质的状态方程及奇异星性质的影响.结果表明,密度依赖口袋常数在低密度处较大,随着密度增大而明显变小,很好地体现了低密度处色禁闭、高密度处夸克退紧闭的量子色动力学(QCD)基本精神.与常数口袋常数的情形相比,密度依赖口袋常数下奇异夸克物质的状态方程变硬,奇异星的引力质量和对应的半径均有明显变大,且均在脉冲星的观测值范围内,表明该模型适合于描述质量和半径较大的奇异星内的夸克物质.     

郑单22玉米不同种植密度对产量的影响

通过不同种植密度对郑单22生长发育及产量影响的研究,郑单22单株叶面积和单株干物质积累量随密度增大而减小。群体叶面积系数和干物质积累量随密度增大而增加,达到一定种植密度后而下降,产量随密度加大而增加,结果表明,郑单22的适宜种植密度为45000~52500株/hm2。     

Effect of Plant Density on Wild Oat Competition with Competitive and Non Competitive Wheat Cultivars

Wild oat (Avena ludoviciana) is one of the worst weeds in wheat fields.The effect of wheat density on wild oat competition with more or less competitive wheat cultivars (Triticum aestivum) was investigated at the Experimental Farm of Plant Pests and Diseases Research Institute,Karaj,Iran.The experiment was established as a factorial combination of wheat varieties Roshan as non-competitive and Niknejad as competitive; three wheat densities (recommended density,recommended+25％,and recommended+50％,corresponding respectively with 300,375,and 450 plants m-2 for Roshan and 400,500,and 600 plants m-2 for Niknejad) and four wild oat densities (0,25,50,and 75 plants m-2) were selected for this experiment.Hyperbolic equations were used to describe relationship between yield and weed density.Increase in wheat density reduced wild oat biomass.Maximum wild oat biomass was achieved at the highest density of the wild oat together with the lowest wheat density.The results showed that higher densities of wheat are able to suppress wild oat dry matter production.Inter-specific competition in Niknejad was 1.7 times more than that in Roshan.Maximum yields of Niknejad and Roshan in the presence of wild oat were obtained at recommended density+25％ and recommended density,respectively.Increase in wheat density leads to a decrease in wheat yield due to an increase in intra-specific competition.Increase in wild oat density results in the reduction of wheat yield through decrease in fertile tiller per plant and spike m-2.     

水稻不同群体的干物质积累特性

从不同品种、不同施肥水平以及不同密度的角度，研究了高产水稻干物质积累的规律。结果表明：中早熟品种比中熟品种齐穗期以前干物质生产旺盛，齐穗期以后则较慢，中熟品种比中早熟品种从齐穗期至成熟期群体干物质增加量多，最终群体总干物质大，穗干重也大；穗干重，从齐穗期至成熟期群体干物质增加重，随着施肥量的增加和移植密度的减少而逐渐增多。     

Effects of Plant Density on Forage Nutritive Value of Whole Plant Corn

In the field experiment, the effects of plant densities (75000, 112 500 and 150 000 plants ha-1) on forage nutritive value of whole plant corn (WPC) were studied from 1999 to 2001.The results demonstrated that with the increasing of plant density, the forage matter yield per plant corn decreased significantly, while the fresh matter and dry matter per hectare corn increased significantly, and a higher grains yield was gotten at higher plant densities. Forage nutritive quality of whole plant corn was changed as plant density increased, the crude protein (CP), ether extract (EE), crude fiber (CF),nitrogen free extract (NFE) and general energy (GE) yields increased obviously. Increasing plant density reasonably with the application of plant growth regulators could improve plant properties, harvest more forage matter, and enhance forage nutritive value of WPC.     

Condensed-matter energetics from diatomic molecular spectra

Analyses of molecular spectra and compression data from crystals show that a single function successfully describes the dependence on interatomic separation of both the potential energy of diatomic molecules and the cohesive binding energy of condensed matter. The empirical finding that one function describes interatomic energies for such diverse forms of matter and over a wide range of conditions can be used to extend condensed-matter equations of state but warrants further theoretical study.     

成品油顺序输送交替过程中摩阻损失的计算

在管道输送成品油过程中,沿线压力的变化主要是由管道特性的变化和不同密度油品在管道中交替产生的,某时刻管道的流量将由各站间供能(启泵方案)、耗能(沿程阻力)以及高程决定。随着混油段的移动,管内流量必然会发生变化。结合实例,对不同油品在管道中交替时摩阻损失随时间的变化进行了计算和分析。     

大落差管道顺序输送中的压力变化和控制方法

顺序输送管道运行中沿线压力的变化主要是由管路特性的变化和不同密度油品在管道中交替产生的，管道落差越大，后者的影响越明显。利用水力计算公式，结合实例，对不同油品在大落差管道中交替时沿线的压力变化规律做了定性和定量的分析。提出了危险点的压力控制措施。     

大豆籽粒干物质积累规律及与产量关系的研究

讨论了新疆高产春大豆品种新大豆1号和石大豆1号在不同种植密度及施肥水平处理下,籽粒干物质的积累规律及其与产量的关系.结果表明:不同品种、施肥水平、种植密度及冠层间的籽粒干物质积累均存在较大差异;植株中、上层籽粒干物质积累量与最后的产量形成关系密切,2个品种中层籽粒的干物质积累与产量形成达显著或极显著正相关.     

Bose-Einstein condensation of cesium

Bose-Einstein condensation of cesium atoms is achieved by evaporative cooling using optical trapping techniques. The ability to tune the interactions between the ultracold atoms by an external magnetic field is crucial to obtain the condensate and offers intriguing features for potential applications. We explore various regimes of condensate self-interaction (attractive, repulsive, and null interaction strength) and demonstrate properties of imploding, exploding, and non-interacting quantum matter.     

新疆天山中部台阶地区甜高粱种植密度与相关生育特征规律的研究

[目的]研究不同种植密度对能源甜高粱品系T601生长发育、各器官干物质积累动态及生物产量的影响.[方法]采用田间试验与室内分析的方法.[结果]不同种植密度下株高、叶龄、茎粗、叶+鞘、茎秆及单株干物质积累均存在差异,且生物产量受种植密度影响较大,不同密度生物产量存在极显著差异.[结论]综合甜高粱各性状分析,在混合肥总量为525 kg/hm2的施肥水平下,种植密度为13.9×104株/hm2时,干物质积累量较大,抗倒伏能力较强,且达到较高的生物产量.     

‘郑单988’玉米不同种植密度对产量的影响

为了确定玉米新品种‘郑单988’的适宜种植密度,对不同种植密度下‘郑单988’的植株性状以及产量等进行了分析对比,通过不同种植密度对‘郑单988’生长发育及产量影响的研究,结果表明：‘郑单988’单株叶面积和单株干物质积累量随密度增大而减小,群体叶面积系数和干物质积累量随密度增大而增加,达到一定种植密度后而下降,产量随密度加大先增后减,‘郑单988’的适宜种植密度为6.0万株/hm2~6.75万株/hm2。     

种植密度对春玉米干物质、氮素积累与转运及产量的影响

以玉米品种陕单609和郑单958为材料,设置4.5(D1)、6.0(D2)、7.5(D3)、9.0(D4)万·hm-2 4个种植密度,研究种植密度对春玉米产量及干物质、氮素转运的影响。结果表明,在D1到D4密度区间,2个品种产量均随密度的增加而增加,在D4密度下最高,分别为13 660.5和13 452kg·hm-2。与D1密度相比,陕单609在D2、D3、D4密度下的产量分别增加16.75%、28.74%、35.34%;郑单958在D2、D3、D4密度下的产量分别增加16.38%、29.96%、37.06%。通过回归方程可知,陕单609最高产密度为10.238万·hm-2,郑单958为9.049 8万·hm-2。叶面积指数、光能截获率随种植密度增加显著增大,而底层透光率显著减小。2个品种的群体干物质积累量和各器官的干物质及氮素积累量、转运量(率)、物质转运对籽粒的贡献率均随种植密度增加而增大。各器官中,氮素积累量、转运量与干物质积累量、转运量呈显著性相关。说明,种植密度通过干物质积累与转运来影响氮素的积累与转运。增加玉米种植密度,有助于增加光合面积、提高有效光能截获率、提高干物质及氮素的积累量和转运量,从而提高玉米籽粒产量。     

种植密度和施氮水平对华南8号木薯产量形成的影响

探讨不同种植密度和施氮水平条件下华南8号木薯干物质积累、分配的规律及其对产量形成的影响。结果表明,低密度低施氮水平处理的产量显著高于高密度高施氮水平处理;低密度低施氮水平处理的单条薯重显著高于高密度高施氮水平处理,并且交互作用显著;低密度和低施氮水平处理虽然前期干物质生产速率较低,但后期干物质生产速率及其向块根的分配比例明显高于高密度和高施氮水平。     

超高产条件下种植密度对泰山21号群体动态、干物质积累和产量的影响

研究了泰山21号的单株最大产量潜力和7个种植密度下的群体动态、产量性状和干物质积累情况。结果表明,在不同的种植密度下,泰山21号的分蘖动态和鲁麦14号有明显的区别,干物质积累和产量都明显高于鲁麦14号,尤其是在拔节至抽穗期和抽穗到成熟期的干物质积累明显高于鲁麦14号,且在耐密性和抗倒性上表现出较大的优势。当基本苗为120-180万/hm2时,泰山21号产量达到最高。     

Twenty-one millisecond pulsars in Terzan 5 using the Green Bank Telescope

We have identified 21 millisecond pulsars (MSPs) in globular cluster Terzan 5 by using the Green Bank Telescope, bringing the total of known MSPs in Terzan 5 to 24. These discoveries confirm fundamental predictions of globular cluster and binary system evolution. Thirteen of the new MSPs are in binaries, of which two show eclipses and two have highly eccentric orbits. The relativistic periastron advance for the two eccentric systems indicates that at least one of these pulsars has a mass 1.68 times greater than the mass of the Sun at 95% confidence. Such large neutron star masses constrain the equation of state of matter at or beyond the nuclear equilibrium density.