趣解“微重力”

＂我国首颗微重力科学实验卫星实践十号将在太空中完成19项微重力科学和空间生命科学实验。那么,微重力到底是什么？实践十号又将怎样进行实验？＂

Gauge Model with massive Gravitons

Gauge theory of gravity is formulated based on principle of local gauge invariance. Because the model hasstrict local gravitational gauge symmetry, and gauge theory of gravity is a perturbatively renormalizable quantum model.However, in the original model, all gauge gravitons are massless. We want to ask whether there exist massive gravitonsin Nature. In this paper, we will propose a gauge model with massive gravitons. The mass term of gravitational gaugefield is introduced into the theory without violating the strict local gravitational gauge symmetry. Massive gravitons canbe considered to be possible origin of dark energy and dark matter in the Universe.

Matter Loops Corrected Modified Gravity in Palatini Formulation

Recently,corrections to the standard Einstein Hilbert action were proposed to explain the current cosmicacceleration in stead of introducing dark energy.In the Palatini formulation of those modified gravity models,thereis an important observation due to Arkani Hamed:matter loops will give rise to a correction to the modified gravityaction proportional to the Ricci scalar of the metric.In the presence of such a term,we show that the current formsof modified gravity models in Palatini formulation,specifically,the 1/R gravity and in R gravity,will have phantoms.Then we study the possible instabilities due to the presence of phantom fields.We show that the strong instability inthe metric formulation of 1/R gravity indicated by Dolgov and Kawasaki will not appear and the decay timescales forthe phantom fields may be long enough for the theories to make sense as effective field theory.On the other hand,if wechange the sign of the modification terms to eliminate the phantoms,some other inconsistencies will arise for the variousversions of the modified gravity models.Finally,we comment on the universal property of the Palatini formulation ofthe matter loops corrected modified gravity models and its implications.

Phantom-Like Effects on Warped DGP Brane

We study phantom-like effect on the DGP brane embedded in a five-dimensional AdS bulk. We show that this effect can be realized without phantom matter on this warped DGP brahe. We investigate the role played by the bulk cosmological constant on the phantom-like effect on the brane and we show that it tends to reduce this effect. Also, warped compactification of the bulk manifold increases the values of the effective and total equation of state parameters of the model relative to the case with Minkowski bulk. We extend our study to the ease that induced curvature on the brahe is modified in the spirit of the f（R）-gravity.

Effects of Rotation, Blocking and Octupole Deformation on Pairing Correlations in the U and Pu Isotopes

including octupole correlations in the Nilsson potential,the ground-state rotational bands in the reflection-asymmetric(RA)nuclei are investigated by using the cranked shell model(CSM)with the monopole and quadrupole pairing correlations treated by a particle-number-conserving(PNC)method.The experimental kinematic moments ofinertia(Mols)for alternating-parity bands in the even-even nuclei ^(236,238)U and ^(238,240)Pu,as well as paritydoublet bands in the odd-A nuclei 237U and 239Pu are reproduced well by the PNC-CSM calculations.The higher J(1)for the intrinsic s=-i bands in ^(237)U and ^(239)Pu,compared with the s=+1 bands in the neighboring even-even nuclei ^(236,238)U and ^(238,240)Pu,can be attributed to the pairing gap reduction due to the Pauli blocking effect.The gradual increase of J(i)versus rotational frequency can be explained by the pairing gap reduction due to the rotation.The Mols of reflection-asymmetric nuclei are higher than those of reflection-symmetric(RS)nuclei at low rotational frequency.Moreover,the inclusion of a larger octupole deformation 8,in the RA nuclei results in more significant pairing gap reduction compared with the RS nuclei.

“花落水流红”的心理基础——论林黛玉进贾府的深层意蕴

林黛玉刚进贾府不久,与宝玉的爱情开始萌芽,就产生了“花落水流红,闲愁万种”和“一年三百六十日,风刀霜剑严相逼”等如此悲痛的感受,这与黛玉进贾府时形成的心理基础密切相关。黛玉是从侧门进入贾府的,并经过十二个层次的“进”,出入25个“门”。贾府重门广宇、庭院深邃,其强大势力的视觉意象一直深压在黛玉心底,进而引发她哀伤绝望的情绪。林黛玉进贾府的艺术意义,不只是表现贾府宏大气象,更是表现贾府强大势力对孤女的心理压抑。

幸福的模样

我是重宇的律师。对面的男人说完把一张名片递给我。我一动没动,视线注视在落地窗外。马路边的长椅上,一个爸爸抱着年幼的孩子,年轻的妈妈在旁边娇笑着,多像我们曾经的模样。你的先生委托我们和您商量一下离婚财产分配的问题。有什么要求,你尽管提,我会转达。他又递过来一堆文件,我没有接。

守护

重宇合众律师事务所的涂律师去北京出差,想顺便去看一下古长城。因种种原因,他还没到过长城,只从书上和网上见过。从小就喜欢画画的涂律师不知画了多少想象中的长城,可他真想去画那真实的威武壮观的城墙。那天,阳光灿烂,他穿过熙熙攘攘的人群和密集的路网,终于来到了朝思暮想的长城边。如见到热恋的恋人,他猛扑过去,激情拥抱着。可在触到墙砖的一瞬间,他的神色凝滞了。那墙砖上被刻着的多国文字,似刻在涂律师心上,生疼,伤口在滴血。他呆望良久,若有所思。

荣宝斋书法馆——精品书画赏析

启功先生是集书法创作、书学理论、考据、诗词于一身的大家,尤其是书法作品名重宇内,为藏家所宝。其书结体取柳公权之谨严,间架端庄,无丝毫懈怠之气;又参以瘦金书的劲健,气息之中,却充沛着"二王"的灵动。启功先生书法中最使人称快的是那些如流水行云般灵动的篇什。如此幅"芝罘长山岛月牙湾拾石子"行书作品,用笔如行云流水、

书香内蒙古·魅力大草原

9月24日,由自治区党委组织部、宣传部、内蒙古新闻出版局联合主办的庆祝新中国成立60周年暨我区全民阅读活动启动仪式在内蒙古展览馆举行。自治区领导巴特尔、任亚平、乌兰、刘新乐等出席了启动仪式。

赤裸的皇帝很幸福

人．向来能够，而且只能够在比较中得到幸福。对于这个观点，我无比赞成。

Constraints of f(R) gravity in Palatini approach with observational Hubble data

We use the newly released observational H(z) data (OHD), the Cosmic Microwave Background (CMB) shift parameter, and the Baryon Acoustic Oscillation (BAO) measurements data to constrain cosmological parameters of f(R) gravity in Palatini formalism in which the f(R) form is defined as f(R) = R β/Rn. Under the assumption of a spatially flat FRW universe, we get the best fitting results of the free parameters (Ωm0, n). In the calculation, we marginalize the likelihood function over H0 by integrating the probability density P ∝ e-χ2/2 to obtain the best fitting results and the confidence regions in the Ωm0-n plane. The constraints results of (Ωm0, n) = (0.33, 0.41) by OHD only and (Ωm0, n) = (0.23, 0.08) by the combination of OHD+CMB+BAO both indicate that the universe goes through three last phases, i.e., radiation dominated, matter-dominated, and late time accelerated expansion without introduction of dark energy.

Reconstruction of Scalar Field Dark Energy Models in Kaluza-Klein Universe

This paper is devoted to study the modified holographic dark energy model by taking its different aspects in the t/at Kaiuza-Klein universe. We construct the equation of state parameter which evolutes the universe from quintessence region towards the vacuum. It is found that the modified holographic model exhibits instability against small perturbations in the early epoch of the universe but becomes stable in the later times. We also develop its correspondence with some scalar field dark energy models. It is interesting to mention here that ail the results are consistent with the present observations.

Modified entropic gravity revisited

Inspired by Verlinde’s idea,some modified versions of entropic gravity have been suggested.Extending them in a unified formalism,herein we derive the generalized gravitational equations accordingly.From gravitational equations,the energy-momentum conservation law and cosmological equations are investigated.The covariant conservation law of energy-momentum tensor severely constrains viable modifications of entropic gravity.A discrepancy arises when two independent methods are applied to the homogeneous isotropic universe,posing a serious challenge to modified models of entropic gravity.

Viscosity Effects on Anisotropic Universe in Curvature-Matter Coupling Gravity

In this paper, we study evolution of the universe in the background of f(R, T) gravity using LRS Bianchi type-Ⅰ model. We discuss scale factors as well as deceleration parameter in dark energy dominated era for different bulk viscosity models. The occurrence of big-rip singularity is also examined. It is concluded that expansion is faster when bulk viscosity is proportional to Hubble parameter as compared to other models.

Cosmology in Massive Gravity

We argue that more cosmological solutions in massive gravity can be obtained if the metric tensor and the tensor ∑μv defined by Stiickelberg fields take the homogeneous and isotropic form. The standard cosmology with matter and radiation dominations in the past can be recovered and ACDM model is easily obtained. The dynamical evolution of the universe is modified at very early times.

Thermodynamics of the Apparent Horizon in FRW Universe with Massive Gravity

Applying Clausius relation with energy-supply defined by the unified first law of thermodynamics formalism to the apparent horizon of a massive gravity model in cosmology proposed lately, the corrected entropic formula of the apparent horizon is obtaJned with the help of the modified Friedmann equations. This entropy-area relation, together with the identified Misner-Sharp internal energy, verifies the first law of thermodynamics for the apparent horizon with a volume change term for consistency. On the other hand, by means of the corrected entropy-area formula and the Clausius relation δQ = T dS, where the heat flow δQ is the energy-supply of pure matter projecting on the vector ξ tangent to the apparent horizon and should be looked on as the amount of energy crossing the apparent horizon during the time interval dt and the temperature of the apparent horizon for energy crossing during the same interval is 1/（2πτA）, the modified Friedmann equations governing the dynamical evolution of the universe are reproduced with the known energy density and pressure of massive graviton. The integration constant is found to correspond to a cosmological term which could be absorbed into the energy density of matter. Having established the correspondence of massive cosmology with the unified first law of thermodynamics on the apparent horizon, the validity of the generalized second law of thermodynamics is also discussed by assuming the thermal equilibrium between the apparent horizon and the matter field bounded by the apparent horizon. It is found that, in the limit Hc → 0, which recovers the Minkowski reference metric solution in the fiat case, the generalized second law of thermodynamics holds if α3 ＋ 4α4 〈 0. Without this condition, even for the simplest model of dRGT massive cosmology with α3= α4 = 0, the generalized second law of thermodynamics could be violated.

f(T) Non-linear Massive Gravity and the Cosmic Acceleration

Inspired by the f（R） non-linear massive gravity, we propose a new kind of modified gravity model, namely f（T） non-linear massive gravity, by adding the dRGT mass term reformulated in the vierbein formalism, to the f（T） theory. We then investigate the cosmological evolution of f（T） massive gravity, and constrain it by using the latest observational data. We find that it slightly favors a crossing of the phantom divide line from the quintessence-like phase （wae 〉 -1） to the phantom-like one （wae 〈 -1） as redshiff decreases.

Baryogenesis in f(R, T) Gravity

We study gravitational baryogenesis in the context of f(R, T) gravity where the gravitational Lagrangian is given by a generic function of the Ricci scalar R and the trace of the stress-energy tensor T. We explore how this type of modified gravity is capable to shed light on the issue of baryon asymmetry in a successful manner. We consider various forms of baryogenesis interaction and discuss the effect of these interaction terms on the baryon to entropy ratio in this setup. We show that baryon asymmetry during the radiation era of the expanding universe can be non-zero in this framework. Then, we calculate the baryon to entropy ratio for some specific f(R, T) models and by using the observational data, we give some constraints on the parameter spaces of these models.