The determination of the apsidal angles and Bertrand's theorem

We derive an expression for the determination of the apsidal angles that holds good for arbitrary central potentials. Then we discuss under what conditions the apsidal angles remain independent of the mechanical energy and angular momentum in the central force problem. As a consequence, an alternative and non-perturbative proof of Bertrand's theorem is obtained.Comment: Latex file, one figure; submitted for publicatio

Evaluation of the Interference of Cyclosporin in the Development of Metastasis in a Low Malignant Murine Tumor [portuguese]

<div> <div> <div> <div> <p> </p><div> <div> <div> <div> <p> Metastasis are secondary tumors that grow from heterogenous cell populations of primary malignant tumors. This phenomenon possibly occur when these cellular populations escape from immunologic surveillance and colonize in distant sites. These secondary tumors are responsible for death in the majority of patients bearing malignant neoplasms. On the other hand, the participation of the immune system is important in some tumors to reduce the malignancy. The subject of this work was to check the influence of Cyclosporine (CS), a immunosupressive drug widely used in organ transplantation, in the development of metastasis from a low malignant primary tumor (fibrohistiocytoma TEGS2047) injected subcutaneously (10⁶ viable clump-free cells). The study was performed in young adult Wistar rats (4-6 weeks old), where the cells exhibited the capacity to grow tumors in 100% of the inoculated animals. Our results showed that in the animals treated with CS (10mg/kg/daily) subcutaneously, the incidence of lung metastasis increased from 4 to 70%, as well as, the growth rate of the primary tumors (p,0.05). These findings suggest the active participation of CS in the inhibition of mechanisms involved in the immunologic surveillance of this tumor. They also corroborate other results from different authors showing increased incidence of malignant tumors in transplanted patients treated with CS.</p><p>Revista de Medicina da Universidade Federal do Ceará, 34(1-2):1-12, 1994</p> </div> </div> </div> </div> </div> </div> </div> </div

Signals from the deep: Spatial and temporal acoustic occurrence of beaked whales off western Ireland - Fig 4

<p><b>Mean Cuvier’s beaked whale detections per recording day bubble plot (right) and with standard error bars (left) for stations 1 (SE = ±0.70), 2 (SE = ±0.59), 3 (SE = ±2.61), 4 (SE = ±4.48), 5 (SE = ±1.08), 6 (SE = ±1.38), 7 (SE = ±1.35), and 8 (SE = ±1.26) off western Ireland from May to Dec 2015 (stations 1–4) and Mar to Nov 2016 (stations 3 and 5–8).</b> Results of Kruskall-Wallis tests are given and results from Tukey-Kramer multiple comparisons tests are represented by coloured means (left) with different colours denoting a statistically significant difference. *Station 8 differs from 7, but not from 3, 5, and 6.</p