Starting Time Point Research Articles

Optimal Open‐Loop Feedback Control of Robots under uncertainty

AbstractThe aim of this presentation is to construct an optimal open‐loop feedback controller for robots, which takes into account stochastic uncertainties. This way, optimal regulators being insensitive with respect to random parameter variations can be obtained.Usually, a precomputed feedback control is based on exactly known or estimated model parameters. However, in practice, often exact informations about model parameters, e.g. the payload mass, are not given. Supposing now that the probability distribution of the random parameter variation is known, in the following, stochastic optimisation methods will be applied in order to obtain robust open‐loop feedback control.Taking into account stochastic parameter variations, the method works with expected cost functions evaluating the primary control expenses and the tracking error. The expectation of the total costs has then to be minimized. Corresponding to Model Predictive Control (MPC), here a sliding horizon is considered. This means that, instead of minimizing an integral from a starting time point t0 to the final time tf, the future time range [t; t+T], with a small enough positive time unit T, will be taken into account. The resulting optimal regulator problem under stochastic uncertainty will be solved by using the Hamiltonian of the problem. After the computation of a H‐minimal control, the related stochastic two‐point boundary value problem is then solved in order to find a robust optimal open‐loop feedback control.The performance of the method will be demonstrated by a numerical example, which will be the control of robot under random variations of the payload mass. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Comparison of Lohmann White and Lohmann Brown Strains in Embryo Physiology

Chicken post-hatch performance is known to be related to embryonic developmental parameters. However, strain or genotype differences with regard to embryo physiological parameters have received little attention. A total of 1,200 hatching eggs produced by Lohmann Brown (LB) and Lohman White (LW) breeders of the same age were studied. Between 62 and 150 h of incubation, eggs Resonance Frequency (RF) was measured as indicator of early embryonic development. Also, albumen pH was measured between setting and d 8 of incubation. From d 10 to 18 of incubation, remaining albumen and embryos were weighed. During the last days of incubation, hatching occurrences were monitored after every four hours and hatched chicks were recorded. Results indicate that RF of LW eggs were lower than that of LB eggs (p<0.01) and starting time point of RF decrease occurred earlier in LB eggs than in LW eggs. Albumen pH of LB eggs was lower than that of LW eggs at day 8 of incubation. Remaining albumen weight at 14 and 16 d of incubation was lower in LB than in LW (p<0.05) while embryo weights increased more rapidly in LB strain than in LW strain. It is concluded that LB and LW embryos have different growth trajectories and should be incubated at different conditions.

Comparison of Cobb and Ross strains in embryo physiology and chick juvenile growth

Broiler performance is known to be related to embryonic developmental parameters. However, strain or genotype differences with regard to embryo physiological parameters and juvenile growth have received little attention. A total of 1,200 hatching eggs produced by Cobb and Ross broiler breeders of the same age were studied. At setting for incubation and between 66 and 130 h of incubation, egg resonant frequency (RF) was measured as an indicator of embryonic development. Also, eggs were weighed before setting and at d 18. From d 10 to 18 of incubation, remaining albumen was weighed. During the last days of incubation, hatching events such as internal pipping (IP), external pipping, and hatch were monitored every 2 h. Hatched chicks were recorded and weighed. At IP stage, gas partial pressures in the egg air chamber were measured. Hatched chicks were reared for 7 d and weighed. Results indicate that RF of Ross eggs were lower than those of Cobb eggs (P < 0.01) and starting time point of RF decrease occurred earlier in Cobb eggs than in Ross eggs. Relative egg weight loss up to 18 d of incubation was lower in Cobb than in Ross (P < 0.05). At IP, partial pressure of CO(2) was higher in Cobb than in Ross (P < 0.05) with shorter incubation duration in Cobb. Between 6 and 60 h posthatch, heat production was higher in Cobb than in Ross (P < 0.05). At 7 d posthatch, Cobb chicks were heavier than Ross chicks (P < 0.05). It is concluded that Cobb and Ross embryos-chicks have different growth trajectories leading in different patterns of growth resulting from differences in physiological parameters.

다차원 스트림 데이터 환경에서 이벤트 가중치를 고려한 시간 관계 탐사

이벤트는 환자의 증상과 같은 시간 속성을 갖는 흐름을 의미하며 센서를 통하여 수집된 스트림 데이터는 시작과 종료 시점을 갖는 인터벌 이벤트로 요약 가능하다. 그러나 대부분의 시간 마이닝 기법은 빈발 이벤트만을 고려하며, 빈발하지 않는 이벤트는 중요하더라도 제외되는 문제가 있다. 이 논문에서는 다차원 스트림 데이터 환경에서 인터벌 이벤트에 기초하여 의미있는 시간 관계에 대한 연관 규칙 마이닝 기법을 제안한다. 제안 방법은 이벤트 가중치와 이상 이벤트가 감지된 시점의 스트림 데이터만 고려하여 이벤트의 발생 횟수에 상관없이 의미있는 시간 관계에 대한 연관 규칙을 탐사한다. 그리고 성능 평가를 통하여 제안 방법이 기존의 방법에 비하여 보다 유용한 지식을 탐사함을 보인다. An event means a flow which has a time attribute such as a symptom of patient. Stream data collected by sensors can be summarized as an interval event which has a time interval between the start-time point and the end-time point in multiple stream data environment. Most of temporal mining techniques have considered only the frequent events. However, these approaches may ignore the infrequent event even if it is important. In this paper, we propose a new temporal data mining that can find association rules for the significant temporal relation based on interval events in multidimensional stream data environment. Our method considers the weight of events and stream data on the sensing time point of abnormal events. And we can discover association rules on the significant temporal relation regardless of the occurrence frequency of events. The experimental analysis has shown that our method provide more useful knowledge than other conventional methods.

Cost Effectiveness of Rituximab Maintenance (R-Maint) vs Autologous Stem Cell Transplant (ASCT) from a UK National Health Service (NHS) Perspective.

Objectives: Both ASCT and R-Maint have been shown to be effective therapies for treating rituximab naïve patients with relapsed/refractory follicular lymphoma. The aim of this research was to assess the cost effectiveness of ASCT compared to R-Maint in this patient population (following a response to chemotherapy induction) from a UK perspective.Methods: A literature review of randomised control trials (RCTs) and case series studies suitable for comparing the efficacy of the two treatments in relapsed / refractory follicular lymphoma patients was performed. Given the heterogeneity of relevant study outcomes and designs a naïve indirect comparison was performed. Equivalent efficacy between the two therapies was assumed based upon the indirect comparison; hence a cost minimization approach was utilized. The starting time point of the analysis was following 3 cycles of CHOP therapy. In the EORTC 20981 trial both RCHOP and CHOP induction therapies were used; to reduce heterogeneity between the trial populations being compared, only results from patients who received CHOP induction in this trial were considered. Drug, administration, adverse event, and monitoring costs were evaluated from the start of treatment to the point of relapse after which time-point cost equivalence was assumed between the two therapies. Resource use and unit costs were sourced from published NHS reference costs, the EORTC 20981 study, and clinical expert opinion. Uncertainty around the assumption of equal efficacy was explored using threshold analysis based on an assumed incremental cost effectiveness ratio (ICER) threshold of £30,000 and an average utility score of 0.71 for patients with follicular lymphoma (derived from the literature).Results: One RCT and 6 case series for ASCT and one RCT for R-Maint were identified. The estimated cost of R-Maint and ASCT was £12,275 and £25,563 respectively, resulting in an estimated incremental cost of ASCT over R-Maint of £13,288 per patient. ASCT would have to offer an additional 7.5 months of overall survival to be considered cost effective compared to R-Maint.Conclusions: There is a high degree of certainty that ASCT produces higher costs compared to R-Maint, however it is uncertain whether ASCT offers an increase in either progression-free or overall survival over R-Maint in rituximab naïve patients. Consequently R-Maint may be considered a cost-saving treatment option for such patients in the treatment of relapsed/refractory follicular lymphoma patients compared to ASCT.

Across-province standardization and comparative analysis of time-to-care intervals for cancer

BackgroundA set of consistent, standardized definitions of intervals and populations on which to report across provinces is needed to inform the Provincial/Territorial Deputy Ministries of Health on progress of the Ten-Year Plan to Strengthen Health Care. The objectives of this project were to: 1) identify a set of criteria and variables needed to create comparable measures of important time-to-cancer-care intervals that could be applied across provinces and 2) use the measures to compare time-to-care across participating provinces for lung and colorectal cancer patients diagnosed in 2004.MethodsA broad-based group of stakeholders from each of the three participating cancer agencies was assembled to identify criteria for time-to-care intervals to standardize, evaluate possible intervals and their corresponding start and end time points, and finalize the selection of intervals to pursue. Inclusion/exclusion criteria were identified for the patient population and the selected time points to reduce potential selection bias. The provincial 2004 colorectal and lung cancer data were used to illustrate across-province comparisons for the selected time-to-care intervals.ResultsCriteria identified as critical for time-to-care intervals and corresponding start and end points were: 1) relevant to patients, 2) relevant to clinical care, 3) unequivocally defined, and 4) currently captured consistently across cancer agencies. Time from diagnosis to first radiation or chemotherapy treatment and the smaller components, time from diagnosis to first consult with an oncologist and time from first consult to first radiation or chemotherapy treatment, were the only intervals that met all four criteria. Timeliness of care for the intervals evaluated was similar between the provinces for lung cancer patients but significant differences were found for colorectal cancer patients.ConclusionWe identified criteria important for selecting time-to-care intervals and appropriate inclusion criteria that were robust across the agencies that did not result in an overly selective sample of patients to be compared. Comparisons of data across three provinces of the selected time-to-care intervals identified several important differences related to treatment and access that require further attention. Expanding this collaboration across Canada would facilitate improvement of and equitable access to quality cancer care at a national level.

Improving source detection and separation in a spatiotemporal Bayesian inference dipole analysis

Most existing spatiotemporal multi-dipole approaches for MEG/EEG source localization assume that the dipoles are active for the full time range being analysed. If the actual time range of activity of sources is significantly shorter than the time range being analysed, the detectability, localization and time-course determination of such sources may be adversely affected, especially for weak sources. In order to improve detectability and reconstruction of such sources, it is natural to add active time range information (starting time point and ending time point of source activation) for each candidate source as unknown parameters in the analysis. However, this adds additional nonlinear free parameters that could burden the analysis and could be unfeasible for some methods. Recently, we described a spatiotemporal Bayesian inference multi-dipole analysis for the MEG/EEG inverse problem. This approach treated the number of dipoles as a free parameter, produced realistic uncertainty estimates using a Markov chain Monte Carlo numerical sampling of the posterior distribution and included a method to reduce the unwanted effects of local minima. In this paper, our spatiotemporal Bayesian inference multi-dipole analysis is extended to incorporate active time range parameters of starting and stopping time points. The properties of this analysis in comparison to the previous one without active time range parameters are demonstrated through extensive studies using both simulated and empirical MEG data.

Grape extracts suppress the formation of preneoplastic foci and activity of fatty acid synthase in rat liver.

This study was conducted to examine the effects of dietary grape extracts on preneoplastic foci formation in rat hepatocarcinogenesis, and related hepatic enzymes. Male Sprague-Dawley rats were fed basal diet or grape diet containing 15% concentrated grape extracts (68 bricks). The grape diet groups were divided into whole-period grape diet group (DEN-GW; grape diet group fed throughout experimental period) and postinitiation grape diet group (DEN-GP; grape diet group fed from post initiation stage) according to the starting time point of the grape diet. Hepatocarcinogenesis was induced by diethylnitrosamine (DEN; 200 mg/kg bw) and 2/3 partial hepatectomy (DEN-B; DEN-treated basal diet group, DEN-GW, and DEN-GP groups), while the control group treated with saline and sham operation (Control group). The formation of placental glutathione (GSH) S-transferase positive (GST-P+) foci in DEN-GW group was moderately but significantly suppressed, however, not in DEN- GP group. Thiobarbituric acid reactive substances content of DEN-GW group was significantly lower than that of DEN-B group. The activity of fatty acid synthase (FAS) in the grape diet groups was decreased about 1/2 of the DEN-B group. The content of GSH and GSH peroxidase activity were increased by carcinogen treatment, but not modulated by grape diet. The activities of GSH S-transferase, p-nitrophenol hydroxylase, and catalase were not affected by diet or treatment. Conclusively, the grape diet-induced reduction of FAS activity that was expressed highly in neoplastic tissues, might be one of the contributing mechanisms of hepatic cancer prevention.

Vibration analysis method

A vibration analysis method for detecting abnormalities by analyzing a vibration waveform. The method includes the steps of, in a plurality of observation time points {t j } composed of a number n of specified time points t j (j=1 to n) counted from a start time point t 0 , detecting displacements of a vibration wave f j (j=1 to n) at the individual time points of the plurality of observation time points, and comparing points in an n-dimensional space composed of the displacements, detected at the individual observation time points, with points in the n-dimensional space of a vibration waveform that are designated as being normal.