FIXED POINTS OF α-TYPE F-CONTRACTIVE MAPPINGS WITH AN APPLICATION TO NONLINEAR FRACTIONAL DIFFERENTIAL EQUATION

In this paper, we introduce new concepts of a-type F-contractive mappings which are essentially weaker than the class of F-contractive mappings given in [21, 22] and different from a-GF-contractions given in [8]. Then, sufficient conditions for the existence and uniqueness of fixed point are established for these new types of contractive mappings, in the setting of complete metric space. Consequently, the obtained results encompass various generalizations of the Banach contraction principle. Moreover, some examples and an application to nonlinear fractional differential equation are given to illustrate the usability of the new theory.

Updating the orbital ephemeris of the dipping source XB 1254–690 and the distance to the source

XB 1254-690 is a dipping low mass X-ray binary system hosting a neutron star and showing type I X-ray bursts. We aim at obtaining a more accurate orbital ephemeris and at constraining the orbital period derivative of the system for the first time. In addition, we want to better constrain the distance to the source in order to locate the system in a well defined evolutive scenario. We apply, for the first time, an orbital timing technique to XB 1254-690, using the arrival times of the dips present in the light curves that have been collected during 26 yr of X-ray pointed observations acquired from different space missions. We estimate the dip arrival times using a statistical method that weights the count-rate inside the dip with respect to the level of persistent emission outside the dip. We fit the obtained delays as a function of the orbital cycles both with a linear and a quadratic function. We infer the orbital ephemeris of XB 1254-690, improving the accuracy of the orbital period with respect to previous estimates. We infer a mass of M2 = 0.42 ± 0.04 M for the donor star, in agreement with estimations already present in literature, assuming that the star is in thermal equilibrium while it transfers part of its mass via the inner Lagrangian point, and assuming a neutron star mass of 1.4 Mo. Using these assumptions, we also constrain the distance to the source, finding a value of 7.6±0.8 kpc. Finally, we discuss the evolution of the system, suggesting that it is compatible with a conservative mass transfer driven by magnetic braking.

FIXED POINT RESULTS ON METRIC-TYPE SPACES

In this paper we obtain fixed point and common fixed point theorems for self- mappings defined on a metric-type space, an ordered metric-type space or a normal cone metric space. Moreover, some examples and an application to integral equations are given to illustrate the usability of the obtained results.

On the Use of SPH for Mechanical Engineering Structural Analyses： An Elastic Linear Case

In this paper the use of Smoothed Particle Hydrodynamics method is presented in the Mechanical Engineering framework. In particular a two dimensional plain strain elastic linear problem is described and solved by two different approaches. Smoothed Particle Hydrodynamics is a meshless computational scheme able to perform an integral representation of a function by means of a smoothing kernel function by involving a finite particle distribution in the discrete formulation. The first approach is derived by the variational formulation of the equilibrium equation, while the second one is a direct differential method. Numerical examples on the cantilever beam problem are implemented to verify and compare the proposed approaches.

Field and Numerical Tests of the Two-Ponding Depth Procedure for Analysis of Single-Ring Pressure Infiltrometer Data

The two-ponding depth （TPD） analysis procedure of single-ring infiltrometer data can yield invalid results, i.e., negative values of the field-saturated soil hydraulic conductivity or the matric flux potential, denoting failure of the two-level run. The objective of this study was to test the performance of the TPD procedure in analyzing the single-ring infiltrometer data of different types of soils. A field investigation carried out in western Sici]y, Italy, yielded higher failure rates （40%） in two clay loam soils than in a sandy loam soil （25%）. A similar result, i.e., fine-textured soils yielding higher failure rates than the coarse-textured one, was obtained using numerically simulated infiltration rates. Soil heterogeneity and reading errors were suggested to be factors determining invalid results in the field. With the numerical data, allowing a less generic definition of soil heterogeneity, invalid TPD results were occasionally obtained with the simultaneous occurrence of a high random variation （standard deviation ≥ 0.5） and a well developed structural correlation for saturated hydraulic conductivity （correlation length 〉 20 cm）. It was concluded that a larger number of replicated runs should be planned to characterize fine-textured soils, where the risk to obtain invalid results is relatively high. Large rings should be used since they appeared more appropriate than the small ones to capture and average soil heterogeneity. Numerical simulation appeared suitable for developing improved strategies of soil characterization for an area of interest, which should also take into account macropore effects.

Mechanisms underlying lineage commitment and plasticity of human yo T cells

Phenotypic and functional heterogeneity are the hallmarks of effector and memory T cells. Upon antigen stimulation, y T cells differentiate into two major types of memory T cells： central memory cells, which patrol the blood and secondary lymphoid organs, and effector memory cells, which migrate to peripheral tissues, y T cells display in vitroa certain degree of plasticity in their function that is reminiscent of that which is observed in conventional CD4 T cells. Similar to CD4 T cells, in which a plethora of specialized subsets affect the host response, y8 T cells may readily and rapidly assume distinct Thl-, Th2-, Th17-, TFH and T regulatory-like effector functions, suggesting that they profoundly influence cell-mediated and humoral immune responses. In addition to differences in cytokine repertoire, y~ T cells exhibit diversity in homing, such as migration to lymph node follicles, to help B cells versus migration to inflamed tissues. Here, we review our current understanding of y T-cell lineage heterogeneity and flexibility, with an emphasis on the human system, and propose a classification of effector y T cells based on distinct functional phenotypes.

Soil Physical Quality of Citrus Orchards Under Tillage, Herbicide, and Organic Managements

Soil capacity to support life and to produce economic goods and services is strongly linked to the maintenance of good soil physical quality(SPQ). In this study, the SPQ of citrus orchards was assessed under three different soil managements, namely no-tillage using herbicides, tillage under chemical farming, and no-tillage under organic farming. Commonly used indicators, such as soil bulk density,organic carbon content, and structural stability index, were considered in conjunction with capacitive indicators estimated by the Beerkan estimation of soil transfer parameter(BEST) method. The measurements taken at the L'Alcoleja Experimental Station in Spain yielded optimal values for soil bulk density and organic carbon content in 100% and 70% of cases for organic farming. The values of structural stability index indicated that the soil was stable in 90% of cases. Differences between the soil management practices were particularly clear in terms of plant-available water capacity and saturated hydraulic conductivity. Under organic farming, the soil had the greatest ability to store and provide water to plant roots, and to quickly drain excess water and facilitate root proliferation.Management practices adopted under organic farming(such as vegetation cover between the trees, chipping after pruning, and spreading the chips on the soil surface) improved the SPQ. Conversely, the conventional management strategies unequivocally led to soil degradation owing to the loss of organic matter, soil compaction, and reduced structural stability. The results in this study show that organic farming has a clear positive impact on the SPQ, suggesting that tillage and herbicide treatments should be avoided.

Dynamical learning of a photonics quantum-state engineering process

Experimental engineering of high-dimensional quantum states is a crucial task for several quantum information protocols.However,a high degree of precision in the characterization of the noisy experimental apparatus is required to apply existing quantum-state engineering protocols.This is often lacking in practical scenarios,affecting the quality of the engineered states.We implement,experimentally,an automated adaptive optimization protocol to engineer photonic orbital angular momentum(OAM)states.The protocol,given a target output state,performs an online estimation of the quality of the currently produced states,relying on output measurement statistics,and determines how to tune the experimental parameters to optimize the state generation.To achieve this,the algorithm does not need to be imbued with a description of the generation apparatus itself.Rather,it operates in a fully black-box scenario,making the scheme applicable in a wide variety of circumstances.The handles controlled by the algorithm are the rotation angles of a series of waveplates and can be used to probabilistically generate arbitrary four-dimensional OAM states.We showcase our scheme on different target states both in classical and quantum regimes and prove its robustness to external perturbations on the control parameters.This approach represents a powerful tool for automated optimizations of noisy experimental tasks for quantum information protocols and technologies.

Dense matter with eXTP

In this White Paper we present the potential of the Enhanced X-ray Timing and Polarimetry(eXTP) mission for determining the nature of dense matter; neutron star cores host an extreme density regime which cannot be replicated in a terrestrial laboratory. The tightest statistical constraints on the dense matter equation of state will come from pulse profile modelling of accretion-powered pulsars, burst oscillation sources, and rotation-powered pulsars. Additional constraints will derive from spin measurements, burst spectra, and properties of the accretion flows in the vicinity of the neutron star. Under development by an international Consortium led by the Institute of High Energy Physics of the Chinese Academy of Sciences, the eXTP mission is expected to be launched in the mid 2020 s.