In the search for habitable planets, the ultimate aspiration is finding an extraterrestrial technical civilization. We already lost a half of century for an active search for extraterrestrial ...civilizations. Should we lose another half? If all civilizations in the Universe are only recipients and not message-sending civilizations, then no SETI (Search for Extraterrestrial Intelligence) searches make any sense. Detecting only leaked radio signals is a hard job with present resources. Fear from the extraterrestrials is unfounded, having in mind physical difficulties and requirements of the interstellar travel. If possible extraterrestrial civilizations are more advanced than ours then they can pick up life signs from Earth easier than we can from their planets at present. Here we propose a scientifically based METI (Messaging to Extraterrestrial Intelligence) program.
Background: Extralevator abdominoperineal excision (ELAPE) is a surgical technique that is indicated for low rectal cancer where sphincter preservation is not possible. Compared to conventional ...abdominoperineal excision major advantages of ELAPE are the risk reduction of intraoperative bowel perforation and positive circumferential margin which lead to a better oncological outcome. The aim of this study was to present our results in ELAPE surgery. Methods: From February 2011 to February 2015, 40 patients underwent surgery for low rectal cancer at the Oncology Institute of Vojvodina. The collected data included sex, age, preoperative staging, neoadjuvant treatment, operative time, rate of intraoperative bowel perforation, rate of positive circumferential resection margins, histopathological analysis, postoperative mortality, tumour, node and metastasis (TNM) classification, local recurrence (LR) rate and presence of distant metastases. Results: Positive circumferential margin was found in three (7.5%) patients while eight (20%) patients had intraoperative bowel perforation. LR during follow-up was seen in seven (17.5%) patients, three of them had intraoperative bowel perforation and two patients had positive circumferential margin. The estimated five-year cumulative incidence of LR is 7%. Distant metastases occurred in 18 (45%) patients. The estimated five-year survival rate is 62%. Conclusion: The study shows satisfactory five-year survival rates of 62% in a highly complex patient group treated by ELAPE procedure.
Process planning is one of the most difficult tasks in product development caused by the large number of technical, technological, economic, environmental and other criteria. Accordingly, the ...selection of manufacturing processes is a complex multi-criteria decision making problem since it considers a number of possible alternative manufacturing processes in addition to a large number of specified criteria. This paper represents the computer-aided methodology for the multi-criteria evaluation and selection of manufacturing processes at the stage of conceptual process planning. The developed methodology is primarily focused on the mapping of product design and manufacturing requirements. Manufacturing processes that fail to meet the given conditions on the basis of 10 criteria such as materials, production volume, productivity, dimensional accuracy, surface finish, etc., are eliminated according to the developed rules. Then, the multi-criteria evaluation and ranking of manufacturing processes is performed based on 5 criteria: manufacturing cycle time, process flexibility, material utilization, quality and operating costs. Based on this methodology, a system is developed for the multi-criteria selection of manufacturing processes, whose implementation is presented in the case of the hip joint endoprosthesis.
Purpose
The present study was designed to investigate whether there is a difference in the anastomotic leakage rate (AL) between the single stapling (CSA) and double stapling (DSA) anastomosis ...techniques.
Methods
One hundred consecutive rectal cancer patients who underwent rectal resection with primary anastomosis were enrolled in this study.
Results
The overall rate of clinical anastomotic leakage in both groups was 7 % (7/100); 6 % (3/50) in the CSA group and 8 % (4/50) in the DSA group. The anastomotic technique did not have any significant influence on the rate of AL. All AL were seen in low anastomoses (7 cm and below). The rate of AL in patients with a diverting stoma (13 %, 3/23) was not significantly different from that of the patients without (5.2 %, 4/77) (
p
= 0.195). The mean length of the operation was significantly shorter in the DSA group compared to the CSA group, at 127 and 141 min, respectively (
p
= 0.005). There were significantly higher rates of AL in patients receiving preoperative long course radiotherapy (15.4 %, 6/39) compared with those who did not receive radiotherapy (1.63 %, 1/61) (
p
= 0.014).
Conclusions
The CSA and DSA techniques are equally safe for the creation of a rectal anastomosis, without any significant difference in the AL rate. However, we recommend using the DSA technique because it has other definite advantages. In cases of neoadjuvant treatment and a low anastomosis, proximal diversion is recommended.
AbstractThe objective of the present paper is to analyze the free vibrations of thin-walled beams with arbitrary open cross section, made of cross-ply laminates with midplane symmetry, by means of an ...exact solution. The theory of thin-walled composite beams is based on assumptions consistent with Vlasov’s beam theory and classical lamination theory. The governing differential equations for coupled bending-torsional vibrations were obtained using the principle of virtual displacements. To simplify the coupled system of differential equations, an ideal center of gravity and shear center were introduced. In the case of a simply supported thin-walled beam, the closed-form solution for the natural frequencies of free harmonic vibrations was derived. The frequency equation, given in determinantal form, is expanded in an explicit analytical form. To demonstrate the validity of this method, the natural frequencies of nonsymmetric thin-walled beams having coupled deformation modes are evaluated and compared with results available in the literature as well as with FEM results.
Flexible manufacturing systems (FMS) represent complex systems with great technological capabilities that are able to simultaneously achieve high level of flexibility, cost effectiveness and ...productivity. However, due to high investment cost and cost of exploitation of the FMS elements, the conditions for their rational use are required. Taking into account the increasingly complex conditions of production and launch of products, a systematic approach in the planning and implementation of FMSs is needed, thereby including the most significant technological and economical characteristics. This paper introduces two methodologies for evaluating the technological effects of application of the FMS elements at the conceptual level along with their verification for a single family of rotational parts.
The aim of this paper was focused on research in order to improve the manufacturing of aluminium alloy thin-walled components through the optimization of milling process parameters. The methodology ...for optimization of milling parameters is developed and presented. The influence of the tool path strategy, wall thickness and feed rate on the machining time, dimensional accuracy deviation, shape and position accuracy deviation, and surface roughness in the case of line-type thin-walled parts machining were analysed. Based on the analysis of experimental results, the corresponding empirical models of responses were identified. Optimization of results was conducted using response surface methodology. Verification of optimization results was executed using two additional experiments. The results from experimental verification show a satisfactory matching with calculated optimal values. The basic scientific contribution of the paper relates to the development of a methodology for optimization of machining parameters for milling of thinwalled structures of aluminium alloy using an ANOVA method, Central Composite Design experiment and empirical modelling. Practical implications are related to the correct selection of the tool path strategy and feed rate value for machining of thin-walled aluminium components in order to achieve the required output techno-economic effects.
We have measured resonance strengths and energies for dielectronic recombination (DR) of Mg-like Fe XV forming Al-like Fe XIV via N = 3 1 N' = 3 core excitations in the electron-ion collision energy ...range 0-45 eV. All measurements were carried out using the heavy-ion test storage ring at the Max Planck Institute for Nuclear Physics in Heidelberg, Germany. We have also carried out new multiconfiguration Breit-Pauli (MCBP) calculations using the AUTOSTRUCTURE code. For electron-ion collision energies unk25 eV we find poor agreement between our experimental and theoretical resonance energies and strengths. From 25 to 42 eV we find good agreement between the two for resonance energies. But in this energy range the theoretical resonance strengths are -31% larger than the experimental results. This is larger than our estimated total experimental uncertainty in this energy range of c26% (at a 90% confidence level). Above 42 eV the difference in the shape between the calculated and measured 3 unk3p( super(1)P sub(1))nl DR series limit we attribute partly to the nl dependence of the detection probabilities of high Rydberg states in the experiment. We have used our measurements, supplemented by our AUTOSTRUCTURE calculations, to produce a Maxwellian-averaged 3 1 3 DR rate coefficient for Fe XV forming Fe XIV. The resulting rate coefficient is estimated to be accurate to better than c29% (at a 90% confidence level) for k sub(B) T sub(e) . l eV. At temperatures of K sub(B) T sub(e) - 2.5-15 eV, where Fe XV is predicted to form in photoionized plasmas, significant discrepancies are found between our experimentally derived rate coefficient and previously published theoretical results. Our new MCBP plasma rate coefficient is 19%-28% smaller than our experimental results over this temperature range.
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