995 resultados para Migration forcée--Colombie
Resumo:
A new 8-node serendipity quadrilateral plate bending element (MQP8) based on the Mindlin-Reissner theory for the analysis of thin and moderately thick plate bending problems using Integrated Force Method is presented in this paper. The performance of this new element (MQP8) is studied for accuracy and convergence by analyzing many standard benchmark plate bending problems. This new element MQP8 performs excellent in both thin and moderately thick plate bending situations. And also this element is free from spurious/zero energy modes and free from shear locking problem.
Resumo:
Force-free equilibrium configurations of magnetic-pressure-dominated magnetized supersonic jets confined by slowly varying external pressure are investigated analytically. For the case where internal dissipation mechanisms are active, the lowest-energy field configuration is found to be the superposition of an axisymmetric mode and a helical mode with a wavelength equal to 5 times the jet radius, and the pressure below which the nonaxisymmetric mode becomes energetically favorable is given as 2700 times the product of the 4th power of the magnetic helicity per unit length and the -6th power of the magnetic flux. A model of the total and polarized emission of such a configuration is developed and applied to the extended well-collimated astronomically resolved jet NGC 6251. The model is shown to reproduce significant features such as transverse oscillations of the ridge line, width oscillations and emission knots, the projected magnetic-field configuration, oscillations of the degree of polarization, and the distribution of the Faraday rotation measure.
Resumo:
It is shown that a magnetic-pressure-dominated, supersonic jet which expands (or contracts) in response to variations in the confining external pressure can dissipate magnetic energy through field-line reconnection as it relaxes to a minimum-energy configuration. In order for a continuous dissipation to take place, the effective reconnection time must be a fraction ɛ ⪉ 1 of the expansion time. The amount of energy dissipation is calculated, and it is concluded that magnetic energy dissipation could, in principle, power the observed synchrotron emission in extragalactic radio jets such as NGC 6251. However, this mechanism is only viable if the reconnection time is substantially shorter than the nominal resistive tearing time in the jet.
Resumo:
In order to study the effect of the Coriolis force due to solar rotation on rising magnetic flux, the authors consider a flux ring, azimuthally symmetric around the rotation axis, starting from rest at the bottom of the convection zone, and then follow the trajectory of the flux ring as it rises. If it is assumed that the flux ring remains azimuthally symmetric during its ascent, then the problem can be described essentially in terms of two parameters: the value of the initial magnetic field in the ring when it starts, and the effective drag experienced by it. For field strengths at the bottom of the convection zone of order 10,000 G or less, it is found that the Coriolis force plays a dominant role and flux rings starting from low latitudes at the bottom are deflected and emerge at latitudes significantly poleward of sunspot zones.
Resumo:
The early stages of plasticity in KBr single crystals have been studied by means of nano-meter-scale indentation in complementary experiments using both a nanoindenter and an atomic force microscope. Nanoindentafion experiments precisely correlate indentation depth and forces, while force microscopy provides high-resolution force measurements and images of the surface revealing dislocation activity. The two methods provide very similar results for the onset of plasticity in KBr. Upon loading we observe yield of the surface in atomic layer units which we attribute to the nucleation of single dislocations. Unloading is accompanied by plastic recovery as evident from a non-linear force distance unloading curve and delayed discrete plasticity events.
Resumo:
A theoretical model is proposed to determine the effects of Si substitution with Al on the oxygen diffusion in apatite-type lanthanum silicates based on density-functional theory (DFT) calculations for La10(SiO 4)4(AlO4)2O2. Substitution changes the stable configuration for excess oxygen from the split interstitial to a new cluster form with the original cluster. Al doping completely changes the migration mechanism from the interstitialcy one, which was proposed for the La9.33(SiO4)6O2 starting material, to a mechanism which contains an interstitial process. Nevertheless, the migration barrier is calculated to be 0.81 eV, which indicates small changes in oxygen conduction and is consistent with the observations. The present study indicates that the cation substitution on silicon site alone does not promise the improvement of the oxide ion conduction in the lanthanum silicate.
Resumo:
Hematogenous metastases are rarely present at diagnosis of ovarian clear cell carcinoma (OCC). Instead dissemination of these tumors is characteristically via direct extension of the primary tumor into nearby organs and the spread of exfoliated tumor cells throughout the peritoneum, initially via the peritoneal fluid, and later via ascites that accumulates as a result of disruption of the lymphatic system. The molecular mechanisms orchestrating these processes are uncertain. In particular, the signaling pathways used by malignant cells to survive the stresses of anchorage-free growth in peritoneal fluid and ascites, and to colonize remote sites, are poorly defined. We demonstrate that the transmembrane glycoprotein CUB-domain-containing protein 1 (CDCP1) has important and inhibitable roles in these processes. In vitro assays indicate that CDCP1 mediates formation and survival of OCC spheroids, as well as cell migration and chemoresistance. Disruption of CDCP1 via silencing and antibody-mediated inhibition markedly reduce the ability of TOV21G OCC cells to form intraperitoneal tumors and induce accumulation of ascites in mice. Mechanistically our data suggest that CDCP1 effects are mediated via a novel mechanism of protein kinase B (Akt) activation. Immunohistochemical analysis also suggested that CDCP1 is functionally important in OCC, with its expression elevated in 90% of 198 OCC tumors and increased CDCP1 expression correlating with poor patient disease-free and overall survival. This analysis also showed that CDCP1 is largely restricted to the surface of malignant cells where it is accessible to therapeutic antibodies. Importantly, antibody-mediated blockade of CDCP1 in vivo significantly increased the anti-tumor efficacy of carboplatin, the chemotherapy most commonly used to treat OCC. In summary, our data indicate that CDCP1 is important in the progression of OCC and that targeting pathways mediated by this protein may be useful for the management of OCC, potentially in combination with chemotherapies and agents targeting the Akt pathway.
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Data mining involves nontrivial process of extracting knowledge or patterns from large databases. Genetic Algorithms are efficient and robust searching and optimization methods that are used in data mining. In this paper we propose a Self-Adaptive Migration Model GA (SAMGA), where parameters of population size, the number of points of crossover and mutation rate for each population are adaptively fixed. Further, the migration of individuals between populations is decided dynamically. This paper gives a mathematical schema analysis of the method stating and showing that the algorithm exploits previously discovered knowledge for a more focused and concentrated search of heuristically high yielding regions while simultaneously performing a highly explorative search on the other regions of the search space. The effective performance of the algorithm is then shown using standard testbed functions and a set of actual classification datamining problems. Michigan style of classifier was used to build the classifier and the system was tested with machine learning databases of Pima Indian Diabetes database, Wisconsin Breast Cancer database and few others. The performance of our algorithm is better than others.
Resumo:
The time evolution of the film thickness and domain formation of octadecylamine molecules adsorbed oil a mica surface is investigated Using atomic force microscopy. The adsorbed Film thickness is determined by measuring the height profile across the mica-amine interface of a mica surface partially immersed in a 15 mM solution of octadecylamine in chloroform. Using this novel procedure, adsorption of amine on mica is found to occur in three distinct stages, with morphologically distinct domain Formation and growth occurring during each stage. In the first stage, where adsorption is primarily in the thin-film regime, all average Film thickness of 0.2 (+/- 0.3) nm is formed for exposure times below 30 s and 0.8 (+/- 0.2) nm for 60 s of immersion time. During this stage, large sample spanning domains are observed. The second stage, which occurs between 60-300 s, is associated with it regime of rapid film growth, and the film thickness increases from about 0.8 to 25 nm during this stage. Once the thick-film regime is established, further exposure to the amine solution results in all increase in the domain area, and it regime of lateral domain growth is observed. In this stage, the domain area coverage grows from 38 to 75%, and the FTIR spectra reveal an increased level of crystallinity in the film. Using it diffusion-controlled model and it two-step Langmuir isotherm, the time evolution of the film growth is quantitatively captured. The model predicts the time at which the thin to thick film transition occurs as well its the time required for complete film growth at longer times. The Ward-Tordai equation is also solved to determine the model parameters in the monolayer (thin-film) regime, which occurs during the initial stages of film growth.
Resumo:
We investigate the effect of hydrodynamic interactions on the non-equilibrium drift dynamics of an ideal flexible polymer pulled by a constant force applied at one polymer end using the perturbation theory and the renormalization group method. For moderate force, if the polymer elongation is small, the hydrodynamic interactions are not screened and the velocity and the longitudinal elongation of the polymer are computed using the renormalization group method. Both the velocity and elongation are nonlinear functions of the driving force in this regime. For large elongation we found two regimes. For large force but finite chain length L the hydrodynamic interactions are screened. For large chain lengths and a finite force the hydrodynamic interactions are only partially screened, which in three dimensions results in unusual logarithmic corrections to the velocity and the longitudinal elongation.
Resumo:
In this paper, we propose a self Adaptive Migration Model for Genetic Algorithms, where parameters of population size, the number of points of crossover and mutation rate for each population are fixed adaptively. Further, the migration of individuals between populations is decided dynamically. This paper gives a mathematical schema analysis of the method stating and showing that the algorithm exploits previously discovered knowledge for a more focused and concentrated search of heuristically high yielding regions while simultaneously performing a highly explorative search on the other regions of the search space. The effective performance of the algorithm is then shown using standard testbed functions, when compared with Island model GA(IGA) and Simple GA(SGA).
Resumo:
Purpose: Testis specific heat-shock protein 70-2 (HSP70-2), a member of HSP70 chaperone family, is essential for the growth of spermatocytes and cancer cells. We investigated the association of HSP70-2 expression with clinical behaviour and progression of urothelial carcinoma of bladder. Experimental design: We assessed the HSP70-2 expression by RT-PCR and HSP70-2 protein expression by immunofluorescence, flow cytometry, immunohistochemistry and Western blotting in urothelial carcinoma patient specimens and HTB-1, UMUC-3, HTB-9, HTB-2 and normal human urothelial cell lines. Further, to investigate the role of HSP70-2 in bladder tumour development, HSP70-2 was silenced in the high-grade invasive HTB-1 and UMUC-3 cells. The malignant properties of urothelial carcinoma cells were examined using colony formation, migration assay, invasion assay in vitro and tumour growth in vivo. Results: Our RT-PCR analysis and immunohistochemistry analysis revealed that HSP70-2 was expressed in both moderate to well-differentiated and high-grade invasive urothelial carcinoma cell lines studied and not in normal human urothelial cells. In consistence with these results, HSP70-2 expression was also observed in superficially invasive (70%) and muscle-invasive (90%) patient's tumours. Furthermore, HSP70-2 knockdown significantly suppressed cellular motility and invasion ability. An in vivo xenograft study showed that inhibition of HSP70-2 significantly suppressed tumour growth. Conclusions: In conclusion, our data suggest that the HSP70-2 expression is associated with early spread and progression of urothelial carcinoma of bladder cancer and that HSP70-2 can be the potential therapeutic target for bladder urothelial carcinoma. (C) 2009 Elsevier Ltd. All rights reserved.
Resumo:
The evacuation of Finnish children to Sweden during WW II has often been called a small migration . Historical research on this subject is scarce, considering the great number of children involved. The present research has applied, apart from the traditional archive research, the framework of history-culture developed by Rüsen in order to have an all-inclusive approach to the impact of this historical event. The framework has three dimensions: political, aesthetic and cognitive. The collective memory of war children has also been discussed. The research looks for political factors involved in the evacuations during the Winter War and the Continuation War and the post-war period. The approach is wider than a purely humanitarian one. Political factors have had an impact in both Finland and Sweden, beginning from the decision-making process and ending with the discussion of the unexpected consequences of the evacuations in the Finnish Parliament in 1950. The Winter War (30.11.1939 13.3.1940) witnessed the first child transports. These were also the model for future decision making. The transports were begun on the initiative of Swedes Maja Sandler, the wife of the resigned minister of foreign affairs Rickard Sandler, and Hanna Rydh-Munck af Rosenschöld , but this activity was soon accepted by the Swedish government because the humanitarian help in the form of child transports lightened the political burden of Prime Minister Hansson, who was not willing to help Finland militarily. It was help that Finland never asked for and it was rejected at the beginning. The negative response of Minister Juho Koivisto was not taken very seriously. The political forces in Finland supporting child transports were stronger than those rejecting them. The major politicians in support belonged to Finland´s Swedish minority. In addition, close to 1 000 Finnish children remained in Sweden after the Winter War. No analysis was made of the reasons why these children did not return home. A committee set up to help Finland and Norway was established in Sweden in 1941. Its chairman was Torsten Nothin, an influential Swedish politician. In December 1941 he appealed to the Swedish government to provide help to Finnish children under the authority of The International Red Cross. This plea had no results. The delivery of great amounts of food to Finland, which was now at war with Great Britain, had automatically caused reactions among the allies against the Swedish imports through Gothenburg. This included the import of oil, which was essential for the Swedish navy and air force. Oil was later used successfully to force a reduction in commerce between Sweden and Finland. The contradiction between Sweden´s essential political interests and humanitarian help was solved in a way that did not harm the country´s vital political interests. Instead of delivering help to Finland, Finnish children were transported to Sweden through the organisations that had already been created. At the beginning of the Continuation War (25.6.1941 27.4.1945) negative opinion regarding child transports re-emerged in Finland. Karl-August Fagerholm implemented the transports in September 1941. In 1942, members of the conservative parties in the Finnish Parliament expressed their fear of losing the children to the Swedes. They suggested that Finland should withdraw from the inter-Nordic agreement, according to which the adoptions were approved by the court of the country where the child resided. This initiative failed. Paavo Virkkunen, an influential member of the conservative party Kokoomus in Finland, favoured the so-called good-father system, where help was delivered to Finland in the form of money and goods. Virkkunen was concerned about the consequences of a long stay in a Swedish family. The risk of losing the children was clear. The extreme conservative party (IKL, the Patriotic Movement of the Finnish People) wanted to alienate Finland from Sweden and bring Finland closer to Germany. Von Blücher, the German ambassador to Finland, had in his report to Berlin, mentioned the political consequences of the child transports. Among other things, they would bring Finland and Sweden closer to each other. He had also paid attention to the Nordic political orientation in Finland. He did not question or criticize the child transports. His main interest was to increase German political influence in Finland, and the Nordic political orientation was an obstacle. Fagerholm was politically ill-favoured by the Germans, because he had a strong Nordic political disposition and had criticised Germany´s activities in Norway. The criticism of child transports was at the same time criticism of Fagerholm. The official censorship organ of the Finnish government (VTL) denied the criticism of child transports in January 1942. The reasons were political. Statements made by members of the Finnish Parliament were also censored, because it was thought that they would offend the Swedes. In addition, the censorship organ used child transports as a means of active propaganda aimed at improving the relations between the two countries. The Finnish Parliament was informed in 1948 that about 15 000 Finnish children still remained in Sweden. These children would stay there permanently. In 1950 the members of the Agrarian Party in Finland stated that Finland should actively strive to get the children back. The party on the left (SKDL, the Democratic Movement of Finnish People) also focused on the unexpected consequences of the child transports. The Social Democrats, and largely Fagerholm, had been the main force in Finland behind the child transports. Members of the SKDL, controlled by Finland´s Communist Party, stated that the war time authorities were responsible for this war loss. Many of the Finnish parents could not get their children back despite repeated requests. The discussion of the problem became political, for example von Born, a member of the Swedish minority party RKP, related this problem to foreign policy by stating that the request to repatriate the Finnish children would have negative political consequences for the relations between Finland and Sweden. He emphasized expressing feelings of gratitude to the Swedes. After the war a new foreign policy was established by Prime Minister (1944 1946) and later President (1946 1956) Juho Kusti Paasikivi. The main cornerstone of this policy was to establish good relations with the Soviet Union. The other, often forgotten, cornerstone was to simultaneously establish good relations with other Nordic countries, especially Sweden, as a counterbalance. The unexpected results of the child evacuation, a Swedish initiative, had violated the good relations with Sweden. The motives of the Democratic Movement of Finnish People were much the same as those of the Patriotic Movement of Finnish People. Only the ideology was different. The Nordic political orientation was an obstacle to both parties. The position of the Democratic Movement of Finnish People was much better than that of the Patriotic Movement of Finnish People, because now one could clearly see the unexpected results, which included human tragedy for the many families who could not be re-united with their children despite their repeated requests. The Swedes questioned the figure given to the Finnish Parliament regarding the number of children permanently remaining in Sweden. This research agrees with the Swedes. In a calculation based on Swedish population registers, the number of these children is about 7 100. The reliability of this figure is increased by the fact that the child allowance programme began in Sweden in 1948. The prerequisite to have this allowance was that the child be in the Swedish population register. It was not necessary for the child to have Swedish nationality. The Finnish Parliament had false information about the number of Finnish children who remained in Sweden in 1942 and in 1950. There was no parliamentary control in Finland regarding child transports, because the decision was made by one cabinet member and speeches by MPs in the Finnish Parliament were censored, like all criticism regarding child transports to Sweden. In Great Britain parliamentary control worked better throughout the whole war, because the speeches regarding evacuation were not censored. At the beginning of the war certain members of the British Labour Party and the Welsh Nationalists were particularly outspoken about the scheme. Fagerholm does not discuss to any great extent the child transports in his memoirs. He does not evaluate the process and results as a whole. This research provides some possibilities for an evaluation of this sort. The Swedish medical reports give a clear picture of the physical condition of the Finnish children when arriving in Sweden. The transports actually revealed how bad the situation of the poorest children was. According to Titmuss, similar observations were made in Great Britain during the British evacuations. The child transports saved the lives of approximately 2 900 children. Most of these children were removed to Sweden to receive treatment for illnesses, but many among the healthy children were undernourished and some suffered from the effects of tuberculosis. The medical inspection in Finland was not thorough. If you compare the figure of 2 900 children saved and returned with the figure of about 7 100 children who remained permanently in Sweden, you may draw the conclusion that Finland as a country failed to benefit from the child transports, and that the whole operation was a political mistake with far-reaching consequenses. The basic goal of the operation was to save lives and have all the children return to Finland after the war. The difficulties with the repatriation of the children were mainly psychological. The level of child psychology in Finland at that time was low. One may question the report by Professor Martti Kaila regarding the adaptation of children to their families back in Finland. Anna Freud´s warnings concerning the difficulties that arise when child evacuees return are also valid in Finland. Freud viewed the emotional life of children in a way different from Kaila: the physical survival of a small child forces her to create strong emotional ties to the person who is looking after her. This, a characteristic of all small children, occurred with the Finnish children too, and it was something the political decision makers in Finland could not see during and after the war. It is a characteristic of all little children. Yet, such experiences were already evident during the Winter War. The best possible solution had been to limit the child transports only to children in need of medical treatment. Children from large and poor families had been helped by organising meals and by buying food from Denmark with Swedish money. Assisting Finland by all possible means should have been the basic goal of Fagerholm in September 1941, when the offer of child transports came from Sweden. Fagerholm felt gratitude towards the Swedes. The risks became clear to him only in 1943. The war children are today a rather scattered and diffuse group of people. Emotionally, part of these children remained in Sweden after the war. There is no clear collective memory, only individual memories; the collective memory of the war children has partly been shaped later through the activities of the war child associations. The main difference between the children evacuated in Finland (for example from Karelia to safer areas with their families) and the war children, who were sent abroad, is that the war children lack a shared story and experience with their families. They were outsiders . The whole matter is sensitive to many of such mothers and discussing the subject has often been avoided in families. The war-time censorship has continued in families through silence and avoidance and Finnish politicians and Finnish families had to face each other on this issue after the war. The lack of all-inclusive historical research has also prevented the formation of a collective awareness among war children returned to Finland or those remaining permanently abroad.. Knowledge of historical facts will help war-children by providing an opportunity to create an all-inclusive approach to the past. Personal experiences should be regarded as part of a large historical entity shadowed by war and where many political factors were at work in both Finland and Sweden. This means strengthening of the cognitive dimension discussed in Rüsen´s all-inclusive historical approach.
Resumo:
In this paper, we propose a self Adaptive Migration Model for Genetic Algorithms, where parameters of population size, the number of points of crossover and mutation rate for each population are fixed adaptively. Further, the migration of individuals between populations is decided dynamically. This paper gives a mathematical schema analysis of the method stating and showing that the algorithm exploits previously discovered knowledge for a more focused and concentrated search of heuristically high yielding regions while simultaneously performing a highly explorative search on the other regions of the search space. The effective performance of the algorithm is then shown using standard testbed functions, when compared with Island model GA(IGA) and Simple GA(SGA).