Pointwise convergence of Birkhoff averages for global observables.

It is well-known that a strict analogue of the Birkhoff Ergodic Theorem in infinite ergodic theory is trivial; it states that for any infinite-measure-preserving ergodic system, the Birkhoff average of every integrable function is almost everywhere zero. Nor does a different rescaling of the Birkhoff sum that leads to a non-degenerate pointwise limit exist. In this paper, we give a version of Birkhoff's theorem for conservative, ergodic, infinite-measure-preserving dynamical systems where instead of integrable functions we use certain elements of L∞ , which we generically call global observables. Our main theorem applies to general systems but requires a hypothesis of "approximate partial averaging" on the observables. The idea behind the result, however, applies to more general situations, as we show with an example. Finally, by means of counterexamples and numerical simulations, we discuss the question of finding the optimal class of observables for which a Birkhoff theorem holds for infinite-measure-preserving systems.

Characterization of DNA methylation as a function of biological complexity via dinucleotide inter-distances.

We perform a statistical study of the distances between successive occurrences of a given dinucleotide in the DNA sequence for a number of organisms of different complexity. Our analysis highlights peculiar features of the CG dinucleotide distribution in mammalian DNA, pointing towards a connection with the role of such dinucleotide in DNA methylation. While the CG distributions of mammals exhibit exponential tails with comparable parameters, the picture for the other organisms studied (e.g. fish, insects, bacteria and viruses) is more heterogeneous, possibly because in these organisms DNA methylation has different functional roles. Our analysis suggests that the distribution of the distances between CG dinucleotides provides useful insights into characterizing and classifying organisms in terms of methylation functionalities.

Machta-Zwanzig regime of anomalous diffusion in infinite-horizon billiards.

We study diffusion on a periodic billiard table with an infinite horizon in the limit of narrow corridors. An effective trapping mechanism emerges according to which the process can be modeled by a Lévy walk combining exponentially distributed trapping times with free propagation along paths whose precise probabilities we compute. This description yields an approximation of the mean squared displacement of infinite-horizon billiards in terms of two transport coefficients, which generalizes to this anomalous regime the Machta-Zwanzig approximation of normal diffusion in finite-horizon billiards [J. Machta and R. Zwanzig, Phys. Rev. Lett. 50, 1959 (1983)PRLTAO0031-900710.1103/PhysRevLett.50.1959].

Measuring logarithmic corrections to normal diffusion in infinite-horizon billiards.

We perform numerical measurements of the moments of the position of a tracer particle in a two-dimensional periodic billiard model (Lorentz gas) with infinite corridors. This model is known to exhibit a weak form of superdiffusion, in the sense that there is a logarithmic correction to the linear growth in time of the mean-squared displacement. We show numerically that this expected asymptotic behavior is easily overwhelmed by the subleading linear growth throughout the time range accessible to numerical simulations. We compare our simulations to analytical results for the variance of the anomalously rescaled limiting normal distributions.

Premalignant and malignant lesions in endometrial polyps in patients undergoing hysteroscopic polypectomy.

OBJECTIVE: To evaluate the incidence of premalignant lesions and cancer in endometrial polyps, in patients undergoing hysteroscopic polypectomy. METHODS: The results of 1,020 pathological examinations of patients submitted to hysteroscopic polypectomy were analyzed, as well as their diagnostic and surgical hysteroscopy findings. As to their menstrual status, 295 (28.9%) patients were in menacme. Of the total, 193 (65.4%) presented abnormal uterine bleeding, and 102 (34.6%) were asymptomatic with altered endometrial echo on transvaginal ultrasound. Out of 725 (71.1%) postmenopausal patients, 171 (23.6%) were symptomatic (abnormal uterine bleeding), and 554 (76.4%) were asymptomatic with endometrial echo >5.0mm. RESULTS: Twenty-one (2.0%) patients presented premalignant lesions in the polyps, 13 had simple glandular hyperplasia, of which 5 had no atypia, and eight presented atypia. Eight polyps presented focal area of complex hyperplasia: 4 with atypia and 4 without lesions. Cancer was diagnosed in 5 (0.5%) polyps. Of the 21 polyps that harbored premalignant lesions, 12 were interpreted as benign in diagnostic and surgical hysteroscopy. Of the polyps with cancer, 4 were also histeroscopically interpreted as normal. CONCLUSION: Symptomatic polyps in menacme and in all postmenopausal women should be resected and submitted to histopathological examination, since they may have a benign aspect, even when harboring areas of cellular atypia or cancer.

Premalignant and malignant lesions in endometrial polyps in patients undergoing hysteroscopic polypectomy / Lesões precursoras e câncer em pólipos do endométrio de pacientes submetidas à polipectomia histeroscópica / Lesões precursoras e câncer em pólipos do endométrio de pacientes submetidas à polipectomia histeroscópica

Objective : To evaluate the incidence of premalignant lesions and cancer in endometrial polyps, in patients undergoing hysteroscopic polypectomy. Methods : The results of 1,020 pathological examinations of patients submitted to hysteroscopic polypectomy were analyzed, as well as their diagnostic and surgical hysteroscopy findings. As to their menstrual status, 295 (28.9%) patients were in menacme. Of the total, 193 (65.4%) presented abnormal uterine bleeding, and 102 (34.6%) were asymptomatic with altered endometrial echo on transvaginal ultrasound. Out of 725 (71.1%) postmenopausal patients, 171 (23.6%) were symptomatic (abnormal uterine bleeding), and 554 (76.4%) were asymptomatic with endometrial echo >5.0mm. Results : Twenty-one (2.0%) patients presented premalignant lesions in the polyps, 13 had simple glandular hyperplasia, of which 5 had no atypia, and eight presented atypia. Eight polyps presented focal area of complex hyperplasia: 4 with atypia and 4 without lesions. Cancer was diagnosed in 5 (0.5%) polyps. Of the 21 polyps that harbored premalignant lesions, 12 were interpreted as benign in diagnostic and surgical hysteroscopy. Of the polyps with cancer, 4 were also histeroscopically interpreted as normal. Conclusion : Symptomatic polyps in menacme and in all postmenopausal women should be resected and submitted to histopathological examination, since they may have a benign aspect, even when harboring areas of cellular atypia or cancer. .

Objetivo : Avaliar a incidência de lesões precursoras e câncer em pólipos do endométrio de pacientes submetidas à polipectomia histeroscópica. Métodos : Análise dos resultados de 1.020 exames anatomopatológicos de pacientes submetidas, em hospital público, à polipectomia histeroscópica, e achados em suas histeroscopias diagnóstica e cirúrgica. Em termos de estado menstrual, 295 (28,9%) pacientes encontravam-se na menacme. Do total, 193 (65,4%) apresentavam sangramento uterino anormal e 102 (34,6%) eram assintomáticas, com alteração da medida do eco endometrial à ultrassonografia transvaginal. Das 725 (71,1%) pacientes na pós-menopausa, 171 (23,6%) eram sintomáticas (sangramento uterino anormal) e 554 (76,4%) assintomáticas, com eco endometrial >5,0mm. Resultados : Vinte e uma (2,0%) pacientes apresentaram lesões precursoras nos pólipos, 13 com hiperplasia glandular simples, das quais 5 sem atipias e 8 com atipias. Oito pólipos apresentavam área focal de hiperplasia complexa, quatro com atipias e quatro sem lesões. Câncer foi diagnosticado em cinco (0,5%) pólipos. Dos 21 pólipos que abrigavam lesões precursoras, 12 foram interpretados como benignos nas histeroscopias diagnóstica e cirúrgica. Quatro dos pólipos com câncer também foram interpretados histeroscopicamente como normais. Conclusão : Os pólipos sintomáticos na menacme, bem como todos na pós-menopausa, devem ser ressecados para realização de exame anatomopatológico, por poderem apresentar aspecto benigno, mesmo quando abrigam áreas de atipia celular ou câncer. .

Recurrence for quenched random Lorentz tubes.

We consider the billiard dynamics in a striplike set that is tessellated by countably many translated copies of the same polygon. A random configuration of semidispersing scatterers is placed in each copy. The ensemble of dynamical systems thus defined, one for each global choice of scatterers, is called quenched random Lorentz tube. We prove that under general conditions, almost every system in the ensemble is recurrent.

Escape orbits for non-compact flat billiards.

It is proven that, under some conditions on f, the non-compact flat billiard Omega={(x,y) in R(0) (+)xR(0) (+); 0

O uso da cola biológica de fibrina em cirurgias laparoscópicas / The use of fibrin biological glue in laparoscopic surgeries

Os autores demonstram o uso da cola biológica de fibrina em 32 cirurgias laparoscópicas. Foram 31 cirurgias de cistos ovarianos de várias etiologias e uma cirurgia de re-anastomose tubária realizadas entre janeiro de 1994 e março de 1995. Embora de várias etiologias, os cistos ovarianos foram todos de natureza benigna. A técnica cirúrgica utilizada nas cirurgias ovarianas foi a da cistectomia, preservando-se o parênquima. Dos cistos ovarianos, 15 eram endometriomas, oito eram cistos serosos, sete eram teratomas e um era cisto mucinoso. A re-anastomose tubária foi realizada em paciente com laqueadura prévia. A cola biológica utilizada foi a cola de fibrina denominada comercialmente Tissucol (Immuno). O resultado foi avaliado pelo aspecto final da cirurgia, isto é, se houve ou nao boa coaptaçao das bordas cirúrgicas. Nas cirurgias ovarianas, todas as pacientes tiveram bons resultados, isto é, as bordas ovarianas ficaram bem aderidas uma a outra. Na cirurgia de re-anastomose tubária, o resultado nao foi bom, pois os cotos proximal e distal acabaram se afastando ao final da cirurgia. Só foi possível, até esta data, a realizaçao de um second-look do total de pacientes incluídas neste estudo.

Miomectomia laparoscópica com uso do bisturi vibratório / Laparoscopic myomectomy using vibratory bistoury

Os autores utilizaram, pela primeira vez no Brasil, o harmonic scapel (bisturi vibratório) na abordagem de uma miomectomia laparoscópica. As características vibratórias do instrumento conferem segurança e uma fácil dissecçao. Os autores concluem que este instrumental vem se incorporar às cirurgias laparoscópicas especialmente às miomectomias.

Miomectomia por via histeroscópica / Miomectomy by histeroscopy

Os autores relatam um caso de paciente portadora de mioma submucoso que foi ressecado por via histeroscópica. A ressecçäo histeroscópica de miomas submucosos e descrita por varios autores europeus e americanos e está sendo introduzida em nosso meio. A técnica exige equipamento completo e experiência da equipe na area de endoscopia ginecológica. A paciente teve alta hospitalar no mesmo dia e o anatomopatológico confirmou tratar-se de mioma submucoso do útero. Os autores concluem que no tratamento dos miomas submucosos a ressecçäo histeroscópica pode ser uma opçäo ao tratamento convencional.

Ablaçäo histeroscópica de endométrio - opçäo à histerectomia em casos selecionados: resultados iniciais / Endometrial hysteroscopy ablation - an option for hysterectomy in selected cases: initial results

Os autores referem sua primeira experiência (cinco casos) com a ablaçÒo do endométrio através da histeroscopia. Este processo pode substituir muitas histerectomias em casos selecionados.

O uso do laser de CO2 em cirurgias videolaparoscópicas: resultados iniciais / The use of CO2 laser in videolaparoscopy surgeries: the initials results

Neste trabalho nós relatamos nossas primeiras experiências com uso do laser de CO2 em videolaparoscopia ginecológica. Diversas cirurgias ginecológicas que antes tinham abordagem apenas por laparotomia foram realizadas por videolaparoscopia e utilizando-se o laser. Os resultados foram considerados bons e acreditamos que o uso do laser CO2 deva ser expandido em ginecologia