About the size of the cosmical systems

In an attempt to explain the apparent absence of satellites of the planet's satellites we have investigated two kinds of hypothesis formally independent of each other. The analysis, though qualitative, suggest that the same parameter links the examined hypothesis.Asociación Argentina de Astronomía (AAA

La metodología de William Herschel

The analysis of the stellar systems which Herschel uses to build his cosmology upon, shows an illustration of the laws of evolution of astronomy which we listed in a previous work. The essential characteristics of Herschel’s method are shown: 1) Application of geometric and kinematic criteria to telescopic observation. 2) The law of gravitation as a universal concept. 3) The analog reasoning of T. Wright and Kant. 4) Lambert's cosmology. These characteristics are discussed in relation to some discoveries of that time; the law of Titius - Bode, the planet Uranus, and the asteroid Ceres.Asociación Argentina de Astronomí

La metodología de William Herschel

The analysis of the stellar systems which Herschel uses to build his cosmology upon, shows an illustration of the laws of evolution of astronomy which we listed in a previous work. The essential characteristics of Herschel’s method are shown: 1) Application of geometric and kinematic criteria to telescopic observation. 2) The law of gravitation as a universal concept. 3) The analog reasoning of T. Wright and Kant. 4) Lambert's cosmology. These characteristics are discussed in relation to some discoveries of that time; the law of Titius - Bode, the planet Uranus, and the asteroid Ceres.Asociación Argentina de Astronomí

La metodología de William Herschel

The analysis of the stellar systems which Herschel uses to build his cosmology upon, shows an illustration of the laws of evolution of astronomy which we listed in a previous work. The essential characteristics of Herschel’s method are shown: 1) Application of geometric and kinematic criteria to telescopic observation. 2) The law of gravitation as a universal concept. 3) The analog reasoning of T. Wright and Kant. 4) Lambert's cosmology. These characteristics are discussed in relation to some discoveries of that time; the law of Titius - Bode, the planet Uranus, and the asteroid Ceres.Asociación Argentina de Astronomí

About the size of the cosmical systems

In an attempt to explain the apparent absence of satellites of the planet's satellites we have investigated two kinds of hypothesis formally independent of each other. The analysis, though qualitative, suggest that the same parameter links the examined hypothesis.Asociación Argentina de Astronomía (AAA

About the size of the cosmical systems

In an attempt to explain the apparent absence of satellites of the planet's satellites we have investigated two kinds of hypothesis formally independent of each other. The analysis, though qualitative, suggest that the same parameter links the examined hypothesis.Asociación Argentina de Astronomía (AAA

Effect of compressive loading on chondrocyte differentiation in agarose cultures of chick limb-bud cells

It is well established that mechanical loading is important to homeostasis of cartilage tissue, and growing evidence suggests that it influences cartilage differentiation as well. Whereas the effect of mechanical forces on chondrocyte biosynthesis and gene expression has been vigorously investigated, the effect of the mechanical environment on chondrocyte differentiation has received little attention. The long-term objective of this research is to investigate the regulatory role of mechanical loading in cell differentiation. The goal of this study was to determine if mechanical compression could modulate chondrocyte differentiation in vitro. Stage 23/24 chick limb-bud cells, embedded in agarose gel, were subjected to either static (constant 4.5-k Pa stress) or cyclic (9.0-kPa peak stress at 0.33 Hz) loading in unconfined compression during the initial phase of commitment to a phenotypic lineage. Compared with nonloaded controls, cyclic compressive loading roughly doubled the number of cartilage nodules and the amount of sulfate incorporation on day 8, whereas static compression had little effect on these two measures. Neither compression protocol significantly affected overall cell viability or the proliferation of cells within nodules. Since limb-bud mesenchymal cells were seeded directly into agarose, an assessment of cartilage nodules in the agarose reflects the proportion of the original cells that had given rise to chondrocytes. Thus, the results indicate that about twice as many mesenchymal cells were induced to enter the chondrogenic pathway by cyclic mechanical compression. The coincidence of the increase in sulfate incorporation and nodule density indicates that the primary effect of mechanical compression on mesenchymal cells was on cellular differentiation and not on their subsequent metabolism. Further studies are needed to identify the primary chondrogenic signal associated with cyclic compressive loading and to determine the mechanism by which it influences commitment to or progression through the chondrogenic lineage, or both.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/34917/1/1100180112_ftp.pd

Tendon mechanobiology: Current knowledge and future research opportunities: TENDON MECHANOBIOLOGY

Tendons mainly function as load-bearing tissues in the muscloskeletal system, transmitting loads from muscle to bone. Tendons are dynamic structures that respond to the magnitude, direction, frequency, and duration of physiologic as well as pathologic mechanical loads via complex interactions between cellular pathways and the highly specialized extracellular matrix. This paper reviews the evolution and current knowledge of mechanobiology in tendon development, homeostasis, disease, and repair. In addition, we review several novel mechanotransduction pathways that have been identified recently in other tissues and cell types, providing potential research opportunities in the field of tendon mechanobiology. We also highlight current methods, models, and technologies being used in a wide variety of mechanobiology research that could be investigated in the context of their potential applicability for answering some of the fundamental unanswered questions in this field. The article concludes with a review of the major questions and future goals discussed during the recent ORS/ISMMS New Frontiers in Tendon Research Conference held September 10–11, 2014 in New York City

Tendinopathy—from basic science to treatment

Chronic tendon pathology (tendinopathy), although common, is difficult to treat. Tendons possess a highly organized fibrillar matrix, consisting of type I collagen and various 'minor' collagens, proteoglycans and glycoproteins. The tendon matrix is maintained by the resident tenocytes, and there is evidence of a continuous process of matrix remodeling, although the rate of turnover varies at different sites. A change in remodeling activity is associated with the onset of tendinopathy. Major molecular changes include increased expression of type III collagen, fibronectin, tenascin C, aggrecan and biglycan. These changes are consistent with repair, but they might also be an adaptive response to changes in mechanical loading. Repeated minor strain is thought to be the major precipitating factor in tendinopathy, although further work is required to determine whether it is mechanical overstimulation or understimulation that leads to the change in tenocyte activity. Metalloproteinase enzymes have an important role in the tendon matrix, being responsible for the degradation of collagen and proteoglycan in both healthy patients and those with disease. Metalloproteinases that show increased expression in painful tendinopathy include ADAM (a disintegrin and metalloproteinase)-12 and MMP (matrix metalloproteinase)-23. The role of these enzymes in tendon pathology is unknown, and further work is required to identify novel and specific molecular targets for therapy