Procedure Robustness Research Articles

Assessing human activity noise in workspaces using machine learning and numerical models

Acoustic comfort of workspace environments is deeply dependent on the balance between indoor background noises. For example, colleagues' speaking might affect task performances by downgrading privacy and productivity. Conversely, HVAC noise can reduce the employee's distraction since such continuous mechanical noise is detrimental to speech comprehension. Therefore, in the analysis of workspaces' acoustic comfort, different background noise sources identification becomes essential. In this regard, machine learning techniques are resourceful for clustering sound pressure level patterns among the unlabeled data. A previous work by the authors provided reliable results on separating noise sources via Gaussian Mixture Model and K-means clustering. Nevertheless, such method was applied to a single workspace, and thus it needs further investigation on a wider sample of environments. For this reason, in the present work long-term monitoring was carried out in various active workspaces extending previous results and confirming the procedure's robustness. Moreover, simulations of the acoustic conditions by summing up the human activity contribution to the mechanical noise allowed obtaining more reliable speech intelligibility criteria at the workstations. Refining the numerical models' setup through background noise levels obtained through machine learning analysis enhance the assessment of workers' privacy condition in realistic scenarios.

Implementation of Quality by Design Methodology in Development and Validation of a New Stability-Indicating, Reverse Phase High-Performance Liquid Chromatography Method for the Rapid Estimation of Piribedil in Piribedil Prolonged Release Tablets

Piribedil is a diazinane compound used in the treatment of Parkinson’s disease. The objective of the current work was to develop a Quality by design based, stability-indicating High-performance liquid chromatography method, with a short runtime to estimate assay in piribedil prolonged release tablets. The assay is an important critical quality attribute of the drug product, which ensures its efficacy. The critical quality attributes were identified and the quality target method profile was defined. Basis of the initial risk assessment, the separation between piribedil and known/unknown degradation products and the sample preparation procedure's robustness were considered critical factors. Phosphate buffer with 0.01 % triethylamine (pH 2.5; 50 mM) and acetonitrile (80:20, v/v) were used as mobile phase. The peaks were resolved using Hypersil gold C18, (4.6×150) mm, 5 μm column within a runtime of 5 min. The mobile phase was pumped at a flow rate of 1.3 ml/min, whereas the column was maintained at 30°. A 5 μl aliquot of each solution was injected and the peak responses were recorded at 238 nm. The critical chromatographic parameters and sample preparation steps were optimized by using Design of experiments and based on its outcome, method operable design ranges were demarcated. An extensive forced degradation study was executed and all the degradant peaks were well separated from the piribedil peak. Piribedil peak was also found homogenous in all the stressed samples. The developed method was validated and found specific, precise, linear, accurate, rugged and robust.

Two Senses of Experimental Robustness: Result Robustness and Procedure Robustness

In the philosophical literature concerning scientific experimentation, the notion of robustness has been solely discussed in relation to experimental results. In this paper, I propose a novel sense of experimental robustness that applies to experimental procedures. I call the foregoing sense of robustness procedure robustness (PR) and characterize it as the capacity of an experimental procedure to maintain its intended function invariant during the experimental process despite possible variations in its inputs. I argue that PR is a precondition for what I call result robustness (RR), which refers to the traditional sense of experimental robustness, namely the existence of convergent experimental results obtained through different and independent means of detection. Furthermore, I argue, PR and RR constitute useful experimental strategies in the context of high-energy physics experiments, but these strategies are not without limitations.

Technical Note: An efficient daily QA procedure for proton pencil beam scanning.

The aim of this work was to develop an efficient daily quality assurance (QA) program with strict tolerance levels for pencil beam scanning (PBS) proton radiotherapy featuring simultaneous dosimetric testing on a single, nonuniform field. A nonuniform field measuring beam output, proton range, and spot position was designed for delivery onto a Sun Nuclear Daily-QA 3 device. A custom acrylic block permitted simultaneous measurement of low- and high-energy proton ranges in addition to beam output. Sensitivities to output, range, and spot position were evaluated to quantitate the device's response. Reproducibility tests were used to identify and control sources of measurement error as well as to assess the QA procedure's robustness. This procedure was implemented in each of our four treatment rooms independently; 4-6months of daily QA measurements were collected. The 1% output, 0.5mm range, and 1.5mm spot position tolerances derived from preliminary tests were tighter overall than tolerances found in the literature and equivalent to the limits used for proton system commissioning. The simplicity and automation of the procedure reduced the time required for daily QA to 10min per treatment room, and competition for beam between multiple treatment rooms was minimized. An efficient daily PBS QA procedure can be performed using a single, nonuniformfield on a nondedicated QA device. A thorough quantitation of the device's response and careful control of measurement uncertainties allowed daily tolerances to match commissioning standards.

Laboratory Information Bulletin: Quantitation of Aflatoxin M1 in Bovine Milk by Liquid Chromatography with Fluorescence Detection

An extraction for aflatoxin M1 from bovine milk samples is described. The samples were extracted by adding 10 mL acetonitrile to 10 g of sample. The extract was salted out with sodium chloride and magnesium sulfate to separate the water and acetonitrile. The organic layer was dried down and reconstituted in water before being subjected to an immunoaffinity column for cleanup. Once the analyte was isolated, quantitation was obtained by LC with fluorescence detection. LC/fluorescence parameters were optimized with an Agilent Poroshell 120 C18 LC column resulting in a 4 min run time. To test the procedure's robustness, three different kinds of matrixes were fortified at three different levels each. Whole milk, reduced fat milk, and skim milk samples were fortified at approximately 0.25, 0.5, and 1.0 μg/kg. Recoveries from all samples ranged from 70 to 100%. Confirmation was accomplished by injecting the samples in an ion trap mass spectrometer. The method presented here entails an extraction step followed by an immunoaffinity column clean-up that leads to fast analysis time and consistent recoveries with an uncertainty measurement of 10.5% and method detection limit of less than 0.011 μg/kg.