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Concept: Systems of measurement

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Lymphatic filariasis (LF)-related disability affects 40 million people globally, making LF the leading cause of physical disability in the world. Despite this, there is limited research into how the impacts of LF-related disability are best measured. This article identifies the tools currently being used to measure LF-related disability and reviews their applicability against the known impacts of LF. The findings from the review show that the generic disability tools currently used by LF programs fail to measure the majority of known impacts of LF-related disability. The findings from the review support the development of an LF-specific disability measurement tool and raise doubt about the suitability of generic disability tools to assess disability related to neglected tropical diseases (NTDs) globally.

Concepts: Measurement, Psychometrics, Test method, Systems of measurement, Filariasis, Neglected diseases, Tropical disease, Tropical diseases

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Ocean surface winds are an essential factor in understanding the physical interactions between the atmosphere and the ocean. Surface winds measured by satellite scatterometers and buoys cover most of the global ocean; however, there are still spatial and temporal gaps and finer-scale variations of wind that may be overlooked, particularly in coastal areas. Here, we show that flight paths of soaring seabirds can be used to estimate fine-scale (every 5 min, ∼5 km) ocean surface winds. Fine-scale global positioning system (GPS) positional data revealed that soaring seabirds flew tortuously and ground speed fluctuated presumably due to tail winds and head winds. Taking advantage of the ground speed difference in relation to flight direction, we reliably estimated wind speed and direction experienced by the birds. These bird-based wind velocities were significantly correlated with wind velocities estimated by satellite-borne scatterometers. Furthermore, extensive travel distances and flight duration of the seabirds enabled a wide range of high-resolution wind observations, especially in coastal areas. Our study suggests that seabirds provide a platform from which to measure ocean surface winds, potentially complementing conventional wind measurements by covering spatial and temporal measurement gaps.

Concepts: Measurement, Navigation, Systems of measurement, Ocean, Wind, Global Positioning System, Wind power, GPS

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Antibiotic tolerance and persistence are often associated with treatment failure and relapse, yet are poorly characterized. In distinction from resistance, which is measured using the minimum inhibitory concentration metric, tolerance and persistence values are not currently evaluated in the clinical setting, and so are overlooked when a course of treatment is prescribed. In this article, we introduce a metric and an automated experimental framework for measuring tolerance and persistence. The tolerance metric is the minimum duration for killing 99% of the population, MDK99, which can be evaluated by a statistical analysis of measurements performed manually or using a robotic system. We demonstrate the technique on strains of Escherichia coli with various tolerance levels. We hope that this, to our knowledge, new approach will be used, along with the existing minimum inhibitory concentration, as a standard for the in vitro characterization of sensitivity to antimicrobials. Quantification of tolerance and persistence may provide vital information in healthcare, and aid research in the field.

Concepts: Bacteria, Statistics, Measurement, Antibiotic resistance, Escherichia coli, Test method, Units of measurement, Systems of measurement

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BACKGROUND: Compartment syndrome of the foot is a rare but life- and limb-threatening condition that is often difficult to diagnose. The common signs and symptoms of compartment syndrome are pain out of proportion to the injury, pain with passive stretch of the compartment, paresis, paresthesias, and often, intact pulses. Foot compartment syndrome is often caused by traumatic injuries, and the clinical presentation may be confusing in this setting. The foot contains nine compartments, which should all be assessed for elevated compartment pressures. Definitive management is fasciotomy. Prompt recognition, diagnosis, and treatment are essential to prevent devastating complications. OBJECTIVES: This article discusses the key components of presentation, diagnosis, and management of foot compartment syndrome. CASE REPORT: A patient presented to the Emergency Department (ED) with a crush injury of his foot. He had significant swelling and pain in his foot, but no fractures were identified on X-ray study. Given the severity of his injury and pain, foot compartment pressures were measured to accurately diagnose foot compartment syndrome. The patient underwent fasciotomies of the foot within 3 h of presentation to the ED and suffered no sequelae at the time of follow-up in clinic. CONCLUSION: Foot compartment syndrome is a surgical emergency that can be difficult to diagnose. Early diagnosis with compartment pressure measurements is crucial, as definitive management with fasciotomies can prevent long-term sequelae.

Concepts: Medical terms, Hospital, Medical diagnosis, Injury, Pressure, Systems of measurement, Pressure measurement, Compartment syndrome

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OBJECTIVES: Combining behavioral and neurophysiological measurements inevitably implies mutual constraints, such as when the neurophysiological measurement requires fast-paced stimulus presentation and hence the attribution of a behavioral response to a particular preceding stimulus becomes ambiguous. We develop and test a method for validly assessing behavioral detection performance in spite of this ambiguity. METHODS: We examine four approaches taken in the literature to treat such situations. We analytically derive a new variant of computing the classical parameters of signal detection theory, hit and false alarm rates, adapted to fast-paced paradigms. RESULTS: Each of the previous approaches shows specific shortcomings (susceptibility towards response window choice, biased estimates of behavioral detection performance). Superior performance of our new approach is demonstrated for both simulated and empirical behavioral data. Further evidence is provided by reliable correspondence between behavioral performance and the N2b component as an electrophysiological indicator of target detection. CONCLUSIONS: The appropriateness of our approach is substantiated by both theoretical and empirical arguments. SIGNIFICANCE: We demonstrate an easy-to-implement solution for measuring target detection performance independent of the rate of event presentation. Thus overcoming the measurement bias of previous approaches, our method will help to clarify the behavioral relevance of different measures of cortical activation.

Concepts: Scientific method, Critical thinking, Measurement, Signal processing, Detection theory, Test method, Systems of measurement, Constant false alarm rate

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The uneven cholesterol distribution among organelles and within the plasma membrane is postulated to be critical for proper cellular function. To study how interactions between cholesterol and specific lipid species contribute to the uneven cholesterol distribution between and within cellular membranes, model lipid membranes are frequently employed. Although the cholesterol distributions within membranes can be directly imaged without labels by using time-of-flight secondary ion mass spectrometry (TOF-SIMS), quantifying the cholesterol abundance at specific membrane locations in a label-free manner remains a challenge. Here, partial least-squares regression (PLSR) of TOF-SIMS data is used to quantitatively measure the local molar percentage (mol%) of cholesterol within supported lipid membranes. Using TOF-SIMS data from lipid membranes of known composition, a PLSR model was constructed that correlated the spectral variation to the mol% cholesterol in the membrane. The PLSR model was then used to measure the mol% cholesterol in test membranes, and to measure cholesterol exchange between vesicles and supported lipid membranes. The accuracy of these measurements was assessed by comparison to the mol% cholesterol measured with conventional assays. By using this TOF-SIMS/PLSR approach to quantify the mol% cholesterol with location specificity, a better understanding of how the regional lipid composition influences cholesterol abundance and exchange in membranes may be obtained.

Concepts: Mass spectrometry, Cell membrane, Measurement, Concentration, Least squares, Lipid bilayer, Systems of measurement, Secondary ion mass spectrometry

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Miranda J, Brunet Ll, Roset P, Farré M, Mendieta C. Reliability of two measurement indices for gingival enlargement. J Periodont Res 2012; 47: 776-782. © 2012 John Wiley & Sons A/S Background and Objective:  The objective of this study was to analyze the concordance of the vertical gingival overgrowth index (GOi) and the horizontal Miranda & Brunet index (MBi) and to compare their reliability and reproducibility for an early diagnosis of gingival enlargement. A wide range of methods has been employed to determine the severity of drug-induced gingival enlargement (DIGE) that has resulted in uncertainty with regard to the prevalence of this side effect. In recent studies, different indices have been used to grade DIGE. The large variability observed between studies and the differences between vertical and horizontal gingival-enlargement measurements could be the result of the use of nonreliable indices during the measurement process. Some indices involve invasive procedures that require many measurements, or even a data-processing system, while others are less convenient and technically expensive and complex. In previous studies we used two complementary indices - the vertical GOi and the horizontal MBi. The results of these studies found some differences between both indices, with the MBi rendering higher estimates of DIGE prevalence that was attributed to its greater sensitivity for the detection of minimal changes in gingival thickness. To our knowledge, there are no studies comparing different measurement indices for gingival enlargement that are supported by statistical concordance analysis. Material and Methods:  Twelve plaster casts from patients who had worn orthodontic brackets, and who had different degrees of chronic inflammatory gingival enlargement, were analyzed. Three previously trained examiners registered twice the degree of buccal overgrowth, using the GOi and MBi, in all cast models with a minimum interval of 7 d between the first and the second evaluation. In total, from each cast, measurements from 16 gingival sites were taken using the GOi, and from nine gingival units (mesial and distal sites measurements) using the MBi. Concordance analysis of the registered measurements (intra-examiner and among examiners) for each index and between indices was assessed using the nonweighted Kappa index with a confidence interval of 95%. Results:  We obtained 648 values for the GOi and the MBi. The overall score 0 (indicating absence of enlargement) was 32.7% and 19.8% for GOi and MBi, respectively, score 1 (light/moderate) was 39.7% and 48.1%, and score 2 (severe) was 27.6% and 32.1%. Concordance analysis for each index showed intra-examiner Kappa values of 0.820 for the GOi and 0.830 for the MBi. Interexaminer Kappa values were 0.720 for the GOi and 0.770 for the MBi. Concordance between indices showed Kappa values for the same examiner of 0.600, whereas concordance among different examiners was 0.550. Discrepancies between indices indicated a systematic skew, with 79-82.1% of discrepancy associated with a higher value for the MBi compared with the GOi. Conclusion:  Both gingival enlargement indices analyzed are reliable, complementary and applicable for measuring gingival overgrowth. However, the MBi shows, with fewer measurements, a greater sensitivity than the GOi for the detection of the early stages of gingival enlargement, being adequate for the screening of large populations at risk.

Concepts: Measurement, Metrology, Psychometrics, Units of measurement, Systems of measurement, Index, Gingival enlargement, Phenytoin

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BACKGROUND: The prevalence of flexible flatfoot is high among preschool-aged children, but the effects of treatment are inconclusive due to the unclear definitions of normal flatfoot. To date, a universally accepted evaluation method of the foot arch in children has not been completely established. Our aims of this study were to establish a new method to evaluate the foot arch from a three dimensional perspective and to investigate the flexibility of the foot arch among children aged from two to six. METHODS: A total of 44 children aged from two to six years of age were put into five age groups in this study. The navicular height was measured with one leg standing, and both feet were scanned separately in both sitting and one leg standing positions to compute the foot arch volume. The arch volume index, which represents the ratio of the difference in volume between sitting and one leg standing positions to the volume when sitting was calculated to demonstrate the flexibility of the foot arch. The differences of measured parameters between each aged group were analyzed by one-way ANOVA. RESULTS: The arch volumes when sitting and standing were highly correlated with the navicular height. The navicular height ranged from 15.75 to 27 mm, the arch volume when sitting ranged from 6,223 to 11,630 mm3, and the arch volume when standing from 3,111 to 7,848 mm3 from two to six years of age. The arch volume index showed a declining trend as age increased. CONCLUSION: This study is the first to describe the foot arch with volume perspective in preschool-aged children. The foot arch volume was highly correlated with the navicular height. Research results show both navicular height index and arch volume index gradually increase with age from two to six. At the same time the arch also becomes rigid with age from two to six. These results could be applied for clinical evaluation of the foot arch and post-treatment evaluation.

Concepts: Foot, Dimension, Ratio, Systems of measurement, Length, Tarsus, Arches of the foot, Flat feet

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Gait speed is simple physical function measure associated with key outcomes in the elderly. Gait speed measurements may improve clinical care in patients with COPD. However, there is a knowledge gap about the reliability and variability of gait speed testing protocols in COPD. We evaluated established techniques of measuring gait speed in patients with COPD, and assessed feasibility of implementing gait speed as a routine vital sign in outpatient clinic.

Concepts: Hospital, Measurement, Psychometrics, Test method, Systems of measurement, Dimensional analysis

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We evaluated how comparable peripheral quantitative computed tomography (pQCT) measurements of cortical thickness, density, and apparent trabecular structure at the ultradistal tibia were with those measured with high-resolution pQCT (HR-pQCT). We also examined whether the accuracy of the pQCT-based trabecular and cortical measurements improved with reductions in slice thickness from the standard 2.2mm to 1.1 and 0.6mm. We immersed 15 dry tibia specimens in saline in a sealed cylinder and scanned 22.5mm from the distal tibia plateau using pQCT and HR-pQCT. pQCT underestimated cortical thickness by Stratec (CThStratec) and trabecular spacing (Tb.Sp) by 21.4% and 72.9%, whereas bone volume to total volume (BV/TV) and cortical density (CDen) were overestimated by 265.8% and 13.1%, respectively. Measurements of trabecular volumetric bone mineral density, trabecular area, total area, cortical thickness by custom software were comparable, but for CThStratec, Tb.Sp, BV/TV, and CDen, the differences between imaging devices varied with magnitude of the estimate. We recommend that researchers or clinicians interested in using pQCT to measure apparent trabecular structure or cortical thickness at the epiphyses, or in comparing findings from different devices, be aware of the differences between HR-pQCT and pQCT.

Concepts: Density, Volume, Measurement, Metrology, Integral, Units of measurement, Quantity, Systems of measurement