945 resultados para Precision Xtra®
Resumo:
We present the DONUTS autoguiding algorithm, designed to fix stellar positions at the sub-pixel level for high-cadence time-series photometry, and also capable of autoguiding on defocused stars. DONUTS was designed to calculate guide corrections from a series of science images and recentre telescope pointing between each exposure. The algorithm has the unique ability of calculating guide corrections from undersampled to heavily defocused point spread functions. We present the case for why such an algorithm is important for high precision photometry and give our results from off and on-sky testing. We discuss the limitations of DONUTS and the facilities where it soon will be deployed.
Resumo:
This paper is an extension to an idea coined during the 13th EUSPEN Conference (P6.23) named "surface defect machining" (SDM). The objective of this work was to demonstrate how a conventional CNC turret lathe can be used to obtain ultra high precision machined surface finish on hard steels without recourse to a sophisticated ultra precision machine tool. An AISI 4340 hard steel (69 HRC) workpiece was machined using a CBN cutting tool with and without SDM. Post-machining measurements by a Form Talysurf and a Scanning Electron Microscope (FEI Quanta 3D) revealed that SDM culminates to several key advantages (i) provides better quality of the machined surface integrity and offers (ii) lowering feed rate to 5μm/rev to obtain a machined surface roughness of 30 nm (optical quality).
Resumo:
Far-travelled volcanic ashes (tephras) from Holocene eruptions in Alaska and the Pacific northwest have been traced to the easternmost extent of North America, providing the basis for a new high-precision geochronological framework throughout the continent through tephrochronology (the dating and correlation of tephra isochrons in sedimentary records). The reported isochrons are geochemically distinct, with seven correlated to documented sources in Alaska and the Cascades, including the Mazama ash from Oregon (w7600 years old) and the eastern lobe of the White River Ash from Alaska (~1150 years old). These findings mark the beginning of a tephrochronological framework of enhanced precision across North America, with applications in palaeoclimate, surface process and archaeological studies. The particle travel distances involved (up tow7000 km) also demonstrate the potential for continent-wide or trans-Atlantic socio-economic disruption from similar future eruptions.
Resumo:
OBJECTIVES: Precision Teaching (PT) has been shown to be an effective intervention to assess teaching method effectiveness and evaluate learning outcomes. SAFMEDS (Say All Fast Minute Every Day Shuffled) are a practice/assessment procedure within the PT framework to assist learning and fluency. We explored the effects of a brief intervention with PT, to impart high frequency performance in safe intravenous fluid prescription in a group of final year undergraduate medical students.
METHODS: 133 final year undergraduate medical students completed a multiple choice question (MCQ) test on safe IV fluid prescription at the beginning and end of the study. The control group (n= 76) of students were taught using a current standardized teaching method. Students allocated to the intervention arm of the study were additionally instructed on PT and the use of SAFMEDS. The study group (n = 57) received 50 SAFMEDS cards containing information on the principles of IV fluid prescription scenarios. These students were trained/tested twice per day for 1 minute.
RESULTS: Interim analysis showed that the study group displayed an improvement in fluency and accuracy as the study progressed. There was a statistically significant improvement in MCQ performance for the PT group compared with the control group between the beginning and end of the study (35% vs 15%).
CONCLUSION: These results suggest PT employing SAFMEDS is an effective method for improving fluency, accuracy and patient safety in intravenous fluid prescribing amongst undergraduate medical students.
Resumo:
The precise knowledge of the temperature of an ultracold lattice gas simulating a strongly correlated
system is a question of both fundamental and technological importance. Here, we address such
question by combining tools from quantum metrology together with the study of the quantum
correlations embedded in the system at finite temperatures. Within this frame we examine the spin-
1 2 XY chain, first estimating, by means of the quantum Fisher information, the lowest attainable
bound on the temperature precision. We then address the estimation of the temperature of the sample
from the analysis of correlations using a quantum non demolishing Faraday spectroscopy method.
Remarkably, our results show that the collective quantum correlations can become optimal
observables to accurately estimate the temperature of our model in a given range of temperatures.
Resumo:
Radiotherapy is commonly planned on the basis of physical dose received by the tumour and surrounding normal tissue, with margins added to address the possibility of geometric miss. However, recent experimental evidence suggests that intercellular signalling results in a given cell's survival also depending on the dose received by neighbouring cells. A model of radiation-induced cell killing and signalling was used to analyse how this effect depends on dose and margin choices. Effective Uniform Doses were calculated for model tumours in both idealised cases with no delivery uncertainty and more realistic cases incorporating geometric uncertainty. In highly conformal irradiation, a lack of signalling from outside the target leads to reduced target cell killing, equivalent to under-dosing by up to 10% compared to large uniform fields. This effect is significantly reduced when higher doses per fraction are considered, both increasing the level of cell killing and reducing margin sensitivity. These effects may limit the achievable biological precision of techniques such as stereotactic radiotherapy even in the absence of geometric uncertainties, although it is predicted that larger fraction sizes reduce the relative contribution of cell signalling driven effects. These observations may contribute to understanding the efficacy of hypo-fractionated radiotherapy.
Resumo:
This paper presents a new series of AMS dates on ultrafiltered bone gelatin extracted from identified cutmarked or humanly-modified bones and teeth from the site of Abri Pataud, in the French Dordogne. The sequence of 32 new determinations provides a coherent and reliable chronology from the site's early Upper Palaeolithic levels 5-14, excavated by Hallam Movius. The results show that there were some problems with the previous series of dates, with many underestimating the real age. The new results, when calibrated and modelled using a Bayesian statistical method, allow detailed understanding of the pace of cultural changes within the Aurignacian I and II levels of the site, something not achievable before. In the future, the sequence of dates will allow wider comparison to similarly dated contexts elsewhere in Europe. High precision dating is only possible by using large suites of AMS dates from humanly-modified material within well understood archaeological sequences modelled using a Bayesian statistical method. © 2011.
Resumo:
Cancer clinical trials have been one of the key foundations for significant advances in oncology. However, there is a clear recognition within the academic, care delivery and pharmaceutical/biotech communities that our current model of clinical trial discovery and development is no longer fit for purpose. Delivering transformative cancer care should increasingly be our mantra, rather than maintaining the status quo of, at best, the often miniscule incremental benefits that are observed with many current clinical trials. As we enter the era of precision medicine for personalised cancer care (precision and personalised medicine), it is important that we capture and utilise our greater understanding of the biology of disease to drive innovative approaches in clinical trial design and implementation that can lead to a step change in cancer care delivery. A number of advances have been practice changing (e.g. imatinib mesylate in chronic myeloid leukaemia, Herceptin in erb-B2-positive breast cancer), and increasingly we are seeing the promise of a number of newer approaches, particularly in diseases like lung cancer and melanoma. Targeting immune checkpoints has recently yielded some highly promising results. New algorithms that maximise the effectiveness of clinical trials, through for example a multi-stage, multi-arm type design are increasingly gaining traction. However, our enthusiasm for the undoubted advances that have been achieved are being tempered by a realisation that these new approaches may have significant cost implications. This article will address these competing issues, mainly from a European perspective, highlight the problems and challenges to healthcare systems and suggest potential solutions that will ensure that the cost/value rubicon is addressed in a way that allows stakeholders to work together to deliver optimal cost-effective cancer care, the benefits of which can be transferred directly to our patients.
Resumo:
OBJECTIVE: The present study aimed to evaluate the precision, ease of use and likelihood of future use of portion size estimation aids (PSEA).
DESIGN: A range of PSEA were used to estimate the serving sizes of a range of commonly eaten foods and rated for ease of use and likelihood of future usage.
SETTING: For each food, participants selected their preferred PSEA from a range of options including: quantities and measures; reference objects; measuring; and indicators on food packets. These PSEA were used to serve out various foods (e.g. liquid, amorphous, and composite dishes). Ease of use and likelihood of future use were noted. The foods were weighed to determine the precision of each PSEA.
SUBJECTS: Males and females aged 18-64 years (n 120).
RESULTS: The quantities and measures were the most precise PSEA (lowest range of weights for estimated portion sizes). However, participants preferred household measures (e.g. 200 ml disposable cup) - deemed easy to use (median rating of 5), likely to use again in future (all scored either 4 or 5 on a scale from 1='not very likely' to 5='very likely to use again') and precise (narrow range of weights for estimated portion sizes). The majority indicated they would most likely use the PSEA preparing a meal (94 %), particularly dinner (86 %) in the home (89 %; all P<0·001) for amorphous grain foods.
CONCLUSIONS: Household measures may be precise, easy to use and acceptable aids for estimating the appropriate portion size of amorphous grain foods.
Resumo:
The speed control system for a concept for cost effective drives with high precision is presented. The drive concept consists of two parallel working drives. The concept is an alternative to direct drives. One big advantage is the use of standard gear boxes with economical components. This paper deals with the control of the drive system consisting of two parts: one drive produces the power for the machine, another drive makes the motion precice and dynamic. Both drives are combined to one double drive by a control system. The drive system is usefull for printing machines and other machines with high power consumption at a nearly constant speed and high accuracy requirements. The calculation for a drive system with 37 kW shows, that the control drive has to supply only about 20 % of the total torque and power needed to compensate the errors of the power drive. The stability of the system is shown by a simulation of the double drive.
Resumo:
The speed control system for a concept for cost effective drives with high precision is presented. The drive concept consists of two parallel working drives. The concept is an alternative to direct drives. One big advantage is the use of standard gear boxes with economical components. This paper deals with the control of the drive system consisting of two parts: one drive produces the power for the machine, another drive makes the motion precice and dynamic. Both drives are combined to one double drive by a control system. The drive system is usefull for printing machines and other machines with high power consumption at a nearly constant speed and high accuracy requirements. The calculation for a drive system with 37 kW shows, that the control drive has to supply only about 20 % of the total torque and power needed to compensate the errors of the power drive. The stability of the system is shown by a simulation of the double drive.
Resumo:
The case describes the development of MyFARM’s internationalization plan, a service of Deimos Engenharia, under the GloCal Radar. This space engineering company hired Lisbon Consulting Company to undertake the project to overcome its lack of market orientation. The consultants’ analysis revealed Stevens County, Kansas, as the market with the highest potential for MyFARM. A suitable entry strategy and adaptation of the service for the local market was proposed. The case culminates with the Board of Directors discussing the viability of implementing the consultants’ recommendations to start diversifying their sources of revenue streams.