Teorias da Aleatoriedade

Este trabalho apresenta uma revisão bibliográfica sobre a definição de “seqüência aleatória”. Nós enfatizamos a definição de Martin-Löf e a definição baseada em incompressividade (complexidade de Kolmogorov). Complexidade de Kolmogorov é uma teoria sofisticada e profunda da informação e da aleatoriedade baseada na máquina de Turing. Estas duas definições resolvem todos os problemas das outras abordagens e satisfazem o nosso conceito intuitivo de aleatoriedade, sendo matematicamente corretas. Adicionalmente, apresentamos a abordagem de Schnorr que inclui um requisito de efetividade (computabilidade) em sua definição. São apresentadas as relações entre estas diversas definições de forma crítica. Palavras-chave: aleatoriedade, complexidade de Kolmogorov, máquina de Turing, computabilidade, probabilidade.This work is a survey about the definition of “random sequence”. We emphasize the definition of Martin-Löf and the definition based on incompressibility (Kolmogorov complexity). Kolmogorov complexity is a profound and sofisticated theory of information and randomness based on Turing machines. These two definitions solve all the problems of the other approaches, satisfying our intuitive concept of randomness, and both are mathematically correct. Furthermore, we show the Schnorr’s approach, that includes a requisite of effectiveness (computability) in his definition. We show the relations between all definitions in a critical way. Keywords: randomness, Kolmogorov complexity, Turing machine, computability, probability

Über eine Klasse polynomialer Scharen selbstadjungierter Operatoren im Hilbertraum

HEK293A cells expressing either mouse MOG (mMOG) or rat MOG (rMOG) C terminally tagged with EGFP. (DOCX 2792 kb

Surgery for fragility hip fracture—streamlining the process

published_or_final_versionSpringer Open Choice, 21 Feb 201

Prevalence of Physical Frailty: Results from the DO-HEALTH Study

Background: Frailty is a geriatric syndrome associated with multiple negative health outcomes. However, its prevalence varies by population and instrument used. We investigated frailty and pre-frailty prevalence by 5 instruments in community-dwelling older adults enrolled to a randomized-controlled trial in 5 European countries. METHODS: Cross-sectional baseline analysis in 2,144 DO-HEALTH participants recruited from Switzerland, Austria, France, Germany, and Portugal with complete data for frailty. Frailty status was assessed by the Physical Frailty Phenotype [PFP], SOF-Frailty Index [SOF-FI], FRAIL-Scale, SHARE-Frailty Instrument [SHARE-FI], and a modified SHARE-FI, and compared by country, age, and gender. Logistic regression was used to determine relevant factors associated with frailty and pre-frailty. RESULTS: Mean age was 74.9 (±4.4) years, 61.6% were women. Based on the PFP, overall frailty and pre-frailty prevalence was 3.0% and 43.0%. By country, frailty prevalence was highest in Portugal (13.7%) and lowest in Austria (0%), and pre-frailty prevalence was highest in Portugal (57.3%) and lowest in Germany (37.1%). By instrument and overall, frailty and pre-frailty prevalence was highest based on SHARE-FI (7.0% / 43.7%) and lowest based on SOF-FI (1.0% / 25.9%). Frailty associated factors were residing in Coimbra (Portugal) [OR 12.0, CI 5.30-27.21], age above 75 years [OR 2.0, CI 1.17-3.45], and female gender [OR 2.8, CI 1.48-5.44]. The same three factors predicted pre-frailty. CONCLUSIONS: Among relatively healthy adults age 70 and older enroled to DO-HEALTH, prevalence of frailty and pre-frailty differed significantly by instrument, country, gender, and age. Among instruments, the highest prevalence of frailty and pre-frailty was documented by the SHARE-FI and the lowest by the SOF-FI

Osteoanabolic effect of alendronate and zoledronate on bone marrow stromal cells (BMSCs) isolated from aged female osteoporotic patients and its implications for their mode of action in the treatment of age-related bone loss

Summary: In the present study, we evaluated the potential for aminobisphosphonates to enhance the development of bone-forming osteoblasts from progenitor cells isolated from aged female osteoporotic patients. The aminobisphosphonates tested significantly enhanced osteoblast formation and thus lend further insights into their possible mode of action in the treatment of osteoporosis. Introduction: The primary aim of this study was to evaluate the influence of aminobisphosphonates on the osteogenesis of human bone marrow stromal cells (hBMSCs) and mineralization of differentiating bone-forming cells isolated from osteoporotic patients. Methods: The influence of aminobisphosphonate treatment on hBMSC osteogenesis was assessed by the quantitative measurement of alkaline phosphatase (ALP) activity, in addition to quantitative reverse transcription polymerase chain reaction and Western blot analysis of known osteogenic markers. Mineralized matrix formation by hBMSC-derived osteoblasts was visualized and quantified using Alizarin red staining. Results: hBMSC cultures treated with osteogenic medium supplemented with zoledronate demonstrated a significant increase in Alizarin red staining after 3weeks as compared to cells cultured in osteogenic medium alone. Similarly, cultures of differentiating hBMSCs isolated from patients receiving alendronate treatment also demonstrated an increased propensity for mineralization, even in the absence of further in vitro stimulation by zoledronate. The stimulatory effects of aminobisphosphonate treatment on hBMSC-derived osteoblast-mediated mineralization were independent of any alterations in ALP activity, although significant decreases in the expression levels of osteopontin (SPP1) were evident in hBMSCs following exposure to aminobisphosphonates. Further analysis including Western blotting and loss-of-function studies revealed osteopontin as having a negative influence on the mineralization of differentiating osteoporotic bone-forming cells. Conclusions: The results presented here demonstrate for the first time that aminobisphosphonate treatment of osteoporotic hBMSCs enhances their capacity for osteoblast formation and subsequent mineral deposition, thus supporting the concept of aminobisphosphonates as having an osteoanabolic effect in osteoporosis

Advantages of the Ilizarov external fixation in the management of intra-articular fractures of the distal tibia

<p>Abstract</p> <p>Background</p> <p>Treatment of distal tibial intra-articular fractures is challenging due to the difficulties in achieving anatomical reduction of the articular surface and the instability which may occur due to ligamentous and soft tissue injury. The purpose of this study is to present an algorithm in the application of external fixation in the management of intra-articular fractures of the distal tibia either from axial compression or from torsional forces.</p> <p>Materials and methods</p> <p>Thirty two patients with intra-articular fractures of the distal tibia have been studied. Based on the mechanism of injury they were divided into two groups. Group I includes 17 fractures due to axial compression and group II 15 fractures due to torsional force. An Ilizarov external fixation was used in 15 patients (11 of group I and 4 of group II). In 17 cases (6 of group I and 11 of group II) a unilateral hinged external fixator was used. In 7 out of 17 fractures of group I an additional fixation of the fibula was performed.</p> <p>Results</p> <p>All fractures were healed. The mean time of removal of the external fixator was 11 weeks for group I and 10 weeks for group II. In group I, 5 patients had radiological osteoarthritic lesions (grade III and IV) but only 2 were symptomatic. Delayed union occurred in 3 patients of group I with fixed fibula. Other complications included one patient of group II with subluxation of the ankle joint after removal of the hinged external fixator, in 2 patients reduction found to be insufficient during the postoperative follow up and were revised and 6 patients had a residual pain. The range of ankle joint motion was larger in group II.</p> <p>Conclusion</p> <p>Intra-articular fractures of the distal tibia due to axial compression are usually complicated with cartilaginous problems and are requiring anatomical reduction of the articular surface. Fractures due to torsional forces are complicated with ankle instability and reduction should be augmented with ligament repair, in order to restore normal movement of talus against the mortise. Both Ilizarov and hinged external fixators are unable to restore ligamentous stability. External fixation is recommended only for fractures of the ankle joint caused by axial compression because it is biomechanically superior and has a lower complication rate.</p

Role of dexamethasone dosage in combination with 5-HT3 antagonists for prophylaxis of acute chemotherapy-induced nausea and vomiting

Dexamethasone (20 mg) or its equivalent in combination with 5-HT3 antagonists appears to be the gold-standard dose for antiemetic prophylaxis. Additional to concerns about the use of corticosteroids with respect to enhanced tumour growth or impaired killing of the tumour cells, there is evidence that high-dosage dexamethasone impairs the control of delayed nausea and emesis, whereas lower doses appear more beneficial. To come closer to the most adequate dose, we started a prospective, single-blind, randomized trial investigating additional dosage of 8 or 20 mg dexamethasone to tropisetron (Navoban), a 5-HT3 receptor antagonist, in cis-platinum-containing chemotherapy. After an interim analysis of 121 courses of chemotherapy in 69 patients, we have been unable to detect major differences between both treatment alternatives. High-dose dexamethasone (20 mg) had no advantage over medium-dose dexamethasone with respect to objective and subjective parameters of acute and delayed nausea and vomiting. In relation to concerns about the use of corticosteroids in non-haematological cancer chemotherapy, we suggest that 8 mg or its equivalent should be used in combination with 5-HT3 antagonists until further research proves otherwise. © 1999 Cancer Research Campaig