Invariance principles for switched systems with restrictions

In this paper we consider switched nonlinear systems under average dwell time switching signals, with an otherwise arbitrary compact index set and with additional constraints in the switchings. We present invariance principles for these systems and derive by using observability-like notions some convergence and asymptotic stability criteria. These results enable us to analyze the stability of solutions of switched systems with both state-dependent constrained switching and switching whose logic has memory, i.e., the active subsystem only can switch to a prescribed subset of subsystems.Comment: 29 pages, 2 Appendixe

The influence of crack-imbalance orientation and orbital evolution for an extended cracked Jeffcott rotor

Vibration peaks occurring at rational fractions of the fundamental rotating critical speed, here named Local Resonances, facilitate cracked shaft detection during machine shut-down. A modified Jeffcott-rotor on journal bearings accounting for gravity effects and oscillating around nontrivial equilibrium points is employed. Modal parameter selection allows this linear model to represent first mode characteristics of real machines. Orbit evolution and vibration patterns are analyzed, yielding useful results. Crack detection results indicate that, instead of 1x and 2x components, analysis of the remaining local resonances should have priority; this is due to crack-residual imbalance interaction and to 2x multiple induced origins. Therefore, local resonances and orbital evolution around 1/2, 1/3 and 1/4 of the critical speed are emphasized for various crack-imbalance orientations

Efectividad cualitativa del ganado caprino en la dispersión de especies de frutos secos y carnosos

[ES] mediterráneo: Cistus salviifolius, C. libanotis, Halimum halimifolium H. calycinum, Myrtus communis, Phillyrea angustifolia, Pistacia lentiscus y Rhamnus lycioides. Frutos de estas especies fueron ofrecidos a seis cabras estabuladas individualmente. Tras la ingestión, se procedió a recoger las heces a intervalos de 24 horas. En las heces recuperadas, se determinó el porcentaje de pérdida de semillas (masticación y digestión), distribución de la recuperación de las semillas en el tiempo y la eficacia germinativa tras el paso por el tracto digestivo. Menos del 30% de las semillas ingeridas fueron recuperadas, con diferencias significativas entre las especies. C. salviifolius presentó el mayor porcentaje de recuperación (casi 30%) y P. lentiscus el menor (0%). Esta tasa de recuperación estuvo significativamente relacionada positivamente con la dureza de las semillas. En la mayoría de las especies, la máxima tasa de recuperación se dio entre las 24-72 horas tras la ingestión. El paso por el intestino de las cabras aumentó significativamente la germinación de C. salviifolius, H. halimifolium, H. calycinum y P. angustifolia. Los resultados de este estudio pusieron de manifiesto que el ganado caprino puede favorecer la dispersión de la mayoría de las semillas de especies cistáceas estudiadas e inhibir la dispersión de semillas de frutos carnosos. El conocimiento de los mecanismos de dispersión por ungulados generalistas son aspectos importantes a tener en cuenta en los planes de gestión, restauración y conservación de los ecosistemas Mediterráneos[EN] We evaluated the role of domestic goats as seed dispersers of eight representative Mediterranean shrub species (Cistus salviifolius, C. libanotis, Halimum halimifolium, H. calycinum, Myrtus communis, Phillyrea angustifolia, Pistacia lentiscus and Rhamnus lycioides). Six female goats of similar size and age were fed with fruits of study species. Following fruits ingestion by goats, total faeces were collected at 24-h intervals. The seeds retrieved were tested for germination and viability, along with seeds not eaten by the goats. Less than 30% of the seeds eaten were retrieved from the dung, with significant differences between species. C. salviifolius showing the maximum recovery percentage (30%), and P. lentiscus the minimum (0%). Seed recovery was significantly related to seed hardness. In most species, the maximum amount of seeds recovered occurred 24-72 h after ingestion. The passage through the goat gut significantly increased seed germination in C. salviifolius, H. halimifolium, H. calycinum and P. angustifolia. The results of this study show that goats can potentially favour (Cistaceae) or inhibit (fleshy fruits) seed dispersal of browsed Mediterranean shrub species. Therefore, these results should be considered when developing conservation and restoration plans of natural vegetation in Mediterranean areasPeer reviewe

Utilización de la cestilla de Moss en el tratamiento de fracturas patológicas vertebrales

Las fracturas patológicas vertebrales pueden inducir radículo o mielopatía compresiva, inestabilidad y deformidad, de tal forma que el objetivo del tratamiento consistiría en restablecer lo más rápidamente posible la anatomía y función. En este sentido la utilización de una malla cilindrica de titanio como la «cestilla de Moss» consigue una estabilidad inmediata y permite la carga precoz. Presentamos un estudio retrospectivo de 6 pacientes afectos de fractura patológica vertebral intervenidos mediante abordaje anterior y estabilización instrumentada combinada con la «cestilla de Moss» rellena de injerto óseo o cemento acrílico. La valoración clínica se realiza subjetivamente por la presencia de dolor y neurológicamente según los grados de Frankel pre y postoperatorios. Radiológicamente se valora la corrección de la cifosis/lordosis/acuñamiento según el método de Cobb. La utilización de la «cestilla de Moss» en fracturas patológicas vertebrales consigue una estabilidad completa sin dependencia de la fusión ósea.Pathological spinal fractures could induce neurological deficit, instability and deformity. Therefore, the objective of the treatment consists of re-establishing the most quickly possible the anatomy and normal function. In this sense, the utilization of a cylindrical mesh of titanium, like the Moss's mesh, provide an immediate stability permiting early loading. We report a retrospective study of 6 patients with pathological spinal fracture operated by anterior decompression and spine stabilization using the Moss's mesh padded of bone graft acrylic cement. Clinical assessment was made subjectively for the presence of pain and neurologic ally according to pre and postoperatively Frankel's grades. The correction of the kyphosis, lordosis and vertebral collapse was assessed according to the Cobb's method. The utilization of the Moss's mesh in pathological spinal fractures provides a complete stability without dependence of the status of bone fusion

Comparison of effectiveness between a conventional catheter and a manual commercial catheter: randomized trial of simulation of intraosseous access in a biological model

Introduction: In the emergency services an action of paramount importance in critically ill patients is to obtain an early vascular access. When vascular access is not established, an intraosseous route should be obtained; otherwise, the mortality of these critically ill patients is almost 100%. In Colombia, the intraosseous access is not used because of the high costs of the devices and the lack of training of the healthcare staff to conduct the procedure.Objective: To determine the efficacy of a low-cost device to establish intraosseous access.Materials and methods: Quantitative approach, experimental design in a simulated environment with chicken tarsus and metatarsus. An analysis was conducted using frequency tables and central tendency measurements. Likewise, further analyses were done using Fisher's exact test, Chi2, and Mann-Whitney test.Results: A total of 99% of the procedures were successful with both catheters. The average time for intraosseous access was 6.6 seconds with Insyte 14 catheter and 4.7 seconds with Din 1515x Illinois Desch device (P=0.001). There were no significant differences in the number of attempts to secure a successful intraosseous access using any of the 2 devices (P=0.56).Conclusion: There was no significant difference between the Ci 14 and the Si 14 catheter to establish a successful intraosseous access in the chicken tarsus and metatarsus in a simulated environment. © 2019 Sociedad Colombiana de Anestesiología y Reanimación (S.C.A.R.E.)