In this paper, we review modified <i>f(R)</i> theories of gravity in Palatini formalism. In this framework, we use the Raychaudhuri’s equation along with the requirement that the gravity is attractive, wh...In this paper, we review modified <i>f(R)</i> theories of gravity in Palatini formalism. In this framework, we use the Raychaudhuri’s equation along with the requirement that the gravity is attractive, which holds for any geometrical theory of gravity to discuss the energy conditions. Then, to derive these conditions, we obtain an expression for effective pressure and energy density by considering FLRW metric. To simply express the energy conditions, we write the Ricci scalar and its derivatives in terms of the deceleration (<i>q</i>), jerk (<i>j</i>) and snap (<i>s</i>) parameters. Energy conditions derived in Palatini version of <i>f(R)</i> Gravity differ from those derived in GR. We will see that the WEC (weak energy condition) derived in Palatini formalism has exactly the same expression in its metric approach.展开更多
In this paper,we propose a hybrid metric Palatini approach in which the Palatini scalar curvature is non minimally coupled to the scalar field.We derive Einstein’s field equations,i.e.,the equations of motion of the ...In this paper,we propose a hybrid metric Palatini approach in which the Palatini scalar curvature is non minimally coupled to the scalar field.We derive Einstein’s field equations,i.e.,the equations of motion of the scalar field.Furthermore,the background and perturbative parameters are obtained by means of Friedmann equations in the slow roll regime.The analysis of cosmological perturbations allowed us to obtain the main inflationary parameters,e.g.,the scalar spectral index and tensor to scalar ratio r.From this perspective,as an application of our analysis,we consider the Higgs field with quartic potential,which plays the inflaton role,and show that predictions of Higgs hybrid inflation are in good agreement with recent observational data[Astron.Astrophys.641,61(2020)].展开更多
In this work,we study the theory of inflation with the non-minimally coupled quadratic,standard model Higgs,and hilltop potentials,throughξφ~2R term in Palatini gravity.We first analyze observational parameters of t...In this work,we study the theory of inflation with the non-minimally coupled quadratic,standard model Higgs,and hilltop potentials,throughξφ~2R term in Palatini gravity.We first analyze observational parameters of the Palatini quadratic potential as functions ofξfor the high-N scenario.In addition to this,taking into account that the inflaton field f has a non-zero vacuum expectation value v after inflation,we display observational parameters of well-known symmetry-breaking potentials.The types of potentials considered are the Higgs potential and its generalizations,namely hilltop potentials in the Palatini formalism for the high-N scenario and the low-N scenario.We calculate inflationary parameters for the Palatini Higgs potential as functions of v for differentξvalues,where inflaton values are bothφ>v andφ<v during inflation,as well as calculating observational parameters of the Palatini Higgs potential in the induced gravity limit for high-N scenario.We illustrate differences between the Higgs potential’s effect onξversus hilltop potentials,which agree with the observations for the inflaton values forφ<v andξ,in which v<<1 for both these high and low N scenarios.For each considered potential,we also display ns-r values fitted to the current data given by the Keck Array/BICEP2 and Planck collaborations.展开更多
目的：建立腭帆张肌（tensor veli palatini，TVP）肌电图的检查方法，获得并分析健康人TVP的肌电图（eletromyography，EMG）特征。方法20例健康成年人在鼻内窥镜介导下，以咽鼓管咽口腭裂前下约3mm作为电极插入点的中点，距该点上、...目的：建立腭帆张肌（tensor veli palatini，TVP）肌电图的检查方法，获得并分析健康人TVP的肌电图（eletromyography，EMG）特征。方法20例健康成年人在鼻内窥镜介导下，以咽鼓管咽口腭裂前下约3mm作为电极插入点的中点，距该点上、下各约2～3mm作为电极插入上、下点分别插入电极，嘱受试者进行一系列的吞咽动作，记录吞咽时TVP的EMG波形，并比较不同电极插入点及不同扫描速度EMG的波形。结果电极位于TVP上点，扫描速度为5ms/div时，共记录20例受试者38侧TVP的EMG，该点能更准确且稳定地获得EMG图形；TVP收缩持续时间为0．863±0．255s，收缩产生的峰电压为445．100±246．808μV，其EMG波型为干扰相；吞咽时双侧TVP收缩同步，未观察到滞后现象。动作电位时程为9．142±2．178ms，动作电位的振幅为254．260±191．544μV，动作电位图形多为2～3相波形。结论电极位于TVP上点，扫描速度为5ms/div时，可以获得更稳定的EMG图形，并获得了正常成人TVP肌电参数的正常范围。展开更多
文摘In this paper, we review modified <i>f(R)</i> theories of gravity in Palatini formalism. In this framework, we use the Raychaudhuri’s equation along with the requirement that the gravity is attractive, which holds for any geometrical theory of gravity to discuss the energy conditions. Then, to derive these conditions, we obtain an expression for effective pressure and energy density by considering FLRW metric. To simply express the energy conditions, we write the Ricci scalar and its derivatives in terms of the deceleration (<i>q</i>), jerk (<i>j</i>) and snap (<i>s</i>) parameters. Energy conditions derived in Palatini version of <i>f(R)</i> Gravity differ from those derived in GR. We will see that the WEC (weak energy condition) derived in Palatini formalism has exactly the same expression in its metric approach.
文摘In this paper,we propose a hybrid metric Palatini approach in which the Palatini scalar curvature is non minimally coupled to the scalar field.We derive Einstein’s field equations,i.e.,the equations of motion of the scalar field.Furthermore,the background and perturbative parameters are obtained by means of Friedmann equations in the slow roll regime.The analysis of cosmological perturbations allowed us to obtain the main inflationary parameters,e.g.,the scalar spectral index and tensor to scalar ratio r.From this perspective,as an application of our analysis,we consider the Higgs field with quartic potential,which plays the inflaton role,and show that predictions of Higgs hybrid inflation are in good agreement with recent observational data[Astron.Astrophys.641,61(2020)].
文摘In this work,we study the theory of inflation with the non-minimally coupled quadratic,standard model Higgs,and hilltop potentials,throughξφ~2R term in Palatini gravity.We first analyze observational parameters of the Palatini quadratic potential as functions ofξfor the high-N scenario.In addition to this,taking into account that the inflaton field f has a non-zero vacuum expectation value v after inflation,we display observational parameters of well-known symmetry-breaking potentials.The types of potentials considered are the Higgs potential and its generalizations,namely hilltop potentials in the Palatini formalism for the high-N scenario and the low-N scenario.We calculate inflationary parameters for the Palatini Higgs potential as functions of v for differentξvalues,where inflaton values are bothφ>v andφ<v during inflation,as well as calculating observational parameters of the Palatini Higgs potential in the induced gravity limit for high-N scenario.We illustrate differences between the Higgs potential’s effect onξversus hilltop potentials,which agree with the observations for the inflaton values forφ<v andξ,in which v<<1 for both these high and low N scenarios.For each considered potential,we also display ns-r values fitted to the current data given by the Keck Array/BICEP2 and Planck collaborations.
文摘目的：建立腭帆张肌（tensor veli palatini，TVP）肌电图的检查方法，获得并分析健康人TVP的肌电图（eletromyography，EMG）特征。方法20例健康成年人在鼻内窥镜介导下，以咽鼓管咽口腭裂前下约3mm作为电极插入点的中点，距该点上、下各约2～3mm作为电极插入上、下点分别插入电极，嘱受试者进行一系列的吞咽动作，记录吞咽时TVP的EMG波形，并比较不同电极插入点及不同扫描速度EMG的波形。结果电极位于TVP上点，扫描速度为5ms/div时，共记录20例受试者38侧TVP的EMG，该点能更准确且稳定地获得EMG图形；TVP收缩持续时间为0．863±0．255s，收缩产生的峰电压为445．100±246．808μV，其EMG波型为干扰相；吞咽时双侧TVP收缩同步，未观察到滞后现象。动作电位时程为9．142±2．178ms，动作电位的振幅为254．260±191．544μV，动作电位图形多为2～3相波形。结论电极位于TVP上点，扫描速度为5ms/div时，可以获得更稳定的EMG图形，并获得了正常成人TVP肌电参数的正常范围。
