Scale-independent Measure Research Articles

An Innovative EEG-Based Pain Identification and Quantification: A Pilot Study.

The present pilot study aimed to propose an innovative scale-independent measure based on electroencephalographic (EEG) signals for the identification and quantification of the magnitude of chronic pain. EEG data were collected from three groups of participants at rest: seven healthy participants with pain, 15 healthy participants submitted to thermal pain, and 66 participants living with chronic pain. Every 30 s, the pain intensity score felt by the participant was also recorded. Electrodes positioned in the contralateral motor region were of interest. After EEG preprocessing, a complex analytical signal was obtained using Hilbert transform, and the upper envelope of the EEG signal was extracted. The average coefficient of variation of the upper envelope of the signal was then calculated for the beta (13-30 Hz) band and proposed as a new EEG-based indicator, namely Piqβ, to identify and quantify pain. The main results are as follows: (1) A Piqβ threshold at 10%, that is, Piqβ ≥ 10%, indicates the presence of pain, and (2) the higher the Piqβ (%), the higher the extent of pain. This finding indicates that Piqβ can objectively identify and quantify pain in a population living with chronic pain. This new EEG-based indicator can be used for objective pain assessment based on the neurophysiological body response to pain. Objective pain assessment is a valuable decision-making aid and an important contribution to pain management and monitoring.

Comparison of 2D and 3D measurement methods for evaluating laser structured aluminum surfaces using fractal dimension

The interlaminar strength of mechanically interlocked polymer-metal hybrids is strongly determined by the surface geometry at the interface. To improve the interlaminar strength, laser beam machining is among the most applied technologies for manufacturing a predefined and complex surface structure. Previously, the fractal dimension of interfaces in polymer-metal-hybrids has been introduced as scale-independent measure. It has been correlated quantitatively with the interlaminar strength using values derived from cross-sectional images. Therefore, the quality of the prediction directly depends on the accuracy of the measured surface data. However, a holistic acquisition of surface structure for the determination of the fractal dimension including 3D methods has not been investigated so far. In this study, laser machining was used to generate five different pin-structures on samples of the aluminum alloy EN AW-6082. Surface characterization was realized by light microscopy (2D), laser scanning microscopy (3D) and X-ray microscopy (3D). Subsequently, the fractal dimension was determined using a box-counting algorithm as well as slit-island method. The results show that all methods regarded are appropriate to determine the fractal dimension, but differ in the specific results. The functional characteristics of each method are described in detail and potentials for applications are outlined.

Robust Isometric Non-Rigid Structure-From-Motion.

Non-Rigid Structure-from-Motion (NRSfM) reconstructs a deformable 3D object from keypoint correspondences established between monocular 2D images. Current NRSfM methods lack statistical robustness, which is the ability to cope with correspondence errors. This prevents one to use automatically established correspondences, which are prone to errors, thereby strongly limiting the scope of NRSfM. We propose a three-step automatic pipeline to solve NRSfM robustly by exploiting isometry. Step (i) computes the optical flow from correspondences, step (ii) reconstructs each 3D point's normal vector using multiple reference images and integrates them to form surfaces with the best reference and step (iii) rejects the 3D points that break isometry in their local neighborhood. Importantly, each step is designed to discard or flag erroneous correspondences. Our contributions include the robustification of optical flow by warp estimation, new fast analytic solutions to local normal reconstruction and their robustification, and a new scale-independent measure of 3D local isometric coherence. Experimental results show that our robust NRSfM method consistently outperforms existing methods on both synthetic and real datasets.

A Novel Approach for Non-Invasive Continuous In-Line Control of Perfusion Cell Cultivations by Raman Spectroscopy.

Continuous manufacturing is becoming more important in the biopharmaceutical industry. This processing strategy is favorable, as it is more efficient, flexible, and has the potential to produce higher and more consistent product quality. At the same time, it faces some challenges, especially in cell culture. As a steady state has to be maintained over a prolonged time, it is unavoidable to implement advanced process analytical technologies to control the relevant process parameters in a fast and precise manner. One such analytical technology is Raman spectroscopy, which has proven its advantages for process monitoring and control mostly in (fed-) batch cultivations. In this study, an in-line flow cell for Raman spectroscopy is included in the cell-free harvest stream of a perfusion process. Quantitative models for glucose and lactate were generated based on five cultivations originating from varying bioreactor scales. After successfully validating the glucose model (Root Mean Square Error of Prediction (RMSEP) of ∼0.2 g/L), it was employed for control of an external glucose feed in cultivation with a glucose-free perfusion medium. The generated model was successfully applied to perform process control at 4 g/L and 1.5 g/L glucose over several days, respectively, with variability of ±0.4 g/L. The results demonstrate the high potential of Raman spectroscopy for advanced process monitoring and control of a perfusion process with a bioreactor and scale-independent measurement method.

The effects of dynamic core-postural chain stabilization on respiratory function, fatigue and activities of daily living in subacute stroke patients: A randomized control trial.

Neurodevelopmental treatment (NDT) and dynamic core-postural chain stabilization (DCS)- based exercise is effective for improving core stability and postural control in stroke patients. However, no study has reported respiratory function, increased fatigue and ADL function in subacute stroke patients by training using NDT and DCS exercises. To compare the effects of DCS and NDT exercises on respiratory function, fatigue and activities of daily living in individuals with hemiparetic stroke. Thirty-one participants with hemiparetic stroke (17 male, 14 female; mean age 60.4±14.58 years; post-stroke duration, 7.2±2.2 weeks) participated in this study. The participants were randomly allocated into DCS (n = 16) and NDT (n = 15). Respiratory function was determined using forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), maximal inspiratory pressure (MIP), and maximal expiratory pressure (MEP). The fatigue severity scale (FSS) and functional independent measure (FIM) were used to evaluate fatigue severity and activities of daily living (ADL). Analysis of covariance (ANCOVA) was used to evaluate post-test differences in the DCS and NDT exercise groups. ANCOVA revealed the superior effects of DCS in respiratory function, as well as clinical FSS and FIM tests, compared with those of NDT (p < 0.05). The results suggest that DCS training was more effective than NDT training at improving respiratory function, fatigue severity and ADL via balanced co-activation of the diaphragm and increased diaphragm movement in individuals with hemiparetic stroke.

Modeling Response Time Distributions with Generalized Beta Prime

We use Generalized Beta Prime distribution, also known as GB2, for fitting response time distributions. This distribution, characterized by one scale and three shape parameters, is incredibly flexible in that it can mimic behavior of many other distributions. GB2 exhibits power-law behavior at both front and tail ends and is a steady-state distribution of a simple stochastic differential equation. We apply GB2 in contrast studies between two distinct groups -- in this case children with dyslexia and a control group -- and show that it provides superior fitting. We compare aggregate response time distributions of the two groups for scale and shape differences (including several scale-independent measures of variability, such as Hoover index), which may in turn reflect on cognitive dynamics differences. In this approach, response time distribution of an individual can be considered as a random variate of that individual's group distribution.

Mixed-species tree plantings enhance structural complexity in oil palm plantations

Conversion of structurally complex rainforests into simplified oil palm monocultures leads to dramatic losses of biodiversity and ecosystem functioning. To alleviate negative ecological impacts, enrichment with native tree species may rapidly restore structural complexity in existing oil palm plantations. However, the mechanisms underlying the recovery of structural complexity in mixed-species tree plantings remain poorly understood. We measured structural complexity from terrestrial laser scanning in a biodiversity enrichment experiment with multiple tree species planted in an oil palm monoculture, forming agroforestry plots of varying tree species diversity and plot size. We find that three years after tree planting, structural complexity in oil palm increased by one third, representing 25% of the increase needed to restore the structural complexity of tropical forests. Changes in structural complexity were associated with denser and more complex filling of three-dimensional space, whereas vertical stratification was mainly influenced by oil palm. Furthermore, structural complexity increased with tree species diversity in the agroforestry plots. This relationship was mainly due the presence of well-performing species that contributed to higher levels of structural complexity. However, interactions among multiple species independently from the species identity were also detected. Finally, increasing plot size had a positive effect on a scale-independent measure of structural complexity. Our results provide evidence that planting multiple tree species in large agroforestry plots is a suitable strategy to rapidly enhance structural complexity in oil palm plantations.

Lumboperitoneal shunt for the treatment of idiopathic normal pressure hydrocephalus

Objective To investigate the clinical outcomes of patients with idiopathic normal pressure hydrocephalus (iNPH) treated with lumboperitoneal shunt (LPS). Methods In this 4-year study (December 2013 to December 2017), we retrospectively analyzed 31 adult patients (age>18 y) with iNPH who underwent preoperative evaluation using HLPS (Huaxi LPS preoperative evaluation scale) at Department of Neurosurgery, West China Hospital, Sichuan University. The improvement of symptoms and imaging following LPS, including Keifer's hydrocephalus score (KHS), Evans index, score of mini-mental state examination (MMSE), complications, shunt revision rate, and quality of life including modified Rankin scale (mRS) and function independent measurement (FIM), were synchronously investigated. Results Compared to preoperative conditions, patients had lower KHS (10.06±5.69 vs. 6.06±4.41, P=0.003) and Evans index (0.35±0.05 vs. 0.27±0.05, P=0.001) at 5 days post LPS. The results of MMSE showed that 9 (29.0%) patients were normal while 15 (48.4%) had mild dementia, 5 (16.1%) had moderate dementia and 2 (6.5%) had severe dementia. At 5 days post LPS, 12 (38.7%) patients were normal while 17 (54.8%) had mild dementia and 2 (6.5%) had severe dementia. Statistical analysis suggested that preoperative and postoperative MMSE scores were significantly different (Z=-3.466, P=0.001). The overall incidence of complications was 35.5%. Six (19.4%) patients had over-drainage, 5(16.1%) reported infection, 3 (9.7%) reported inadequate drainage, and 1 (3.2%) developed abdominal symptoms. The median follow-up duration was 9 (1- 48) months. The follow-up indicated that the overall rate of shunt failure was 19.4% and the median of mRS and FIM were 1 (0-5) and 93.5 (23-126), respectively. Conclusion Patients who underwent evaluation before LPS using HLPS could have favorable clinical outcomes with low failure rate. Key words: Hydrocephalus, normal pressure; Treatment outcome; Idiopathic; Lumboperitoneal shunt

Synchrony changes on different time-scales during in vitro neuronal network development

Synchrony changes on different time-scales during in vitro neuronal network development

Spike-contrast: A novel time scale independent and multivariate measure of spike train synchrony

BackgroundSynchrony within neuronal networks is thought to be a fundamental feature of neuronal networks. In order to quantify synchrony between spike trains, various synchrony measures were developed. Most of them are time scale dependent and thus require the setting of an appropriate time scale. Recently, alternative methods have been developed, such as the time scale independent SPIKE-distance by Kreuz et al. New methodIn this study, a novel time-scale independent spike train synchrony measure called Spike-contrast is proposed. The algorithm is based on the temporal “contrast” (activity vs. non-activity in certain temporal bins) and not only provides a single synchrony value, but also a synchrony curve as a function of the bin size. ResultsFor most test data sets synchrony values obtained with Spike-contrast are highly correlated with those of the SPIKE-distance (Spearman correlation value of 0.99). Correlation was lower for data containing multiple time scales (Spearman correlation value of 0.89). When analyzing large sets of data, Spike-contrast performed faster. Comparison of existing methodSpike-contrast is compared to the SPIKE-distance algorithm. The test data consisted of artificial spike trains with various levels of synchrony, including Poisson spike trains and bursts, spike trains from simulated neuronal Izhikevich networks, and bursts made of smaller bursts (sub-bursts). ConclusionsThe high correlation of Spike-contrast with the established SPIKE-distance for most test data, suggests the suitability of the proposed measure. Both measures are complementary as SPIKE-distance provides a synchrony profile over time, whereas Spike-contrast provides a synchrony curve over bin size.

The use of scale independent shape measures to assess open stope performance

1. IntroductionExcavation performance in bulk underground mining applica-tions, such as open stoping, is generally assessed by the ability toachieve maximum extraction with minimal dilution. The successof open stoping methods relies on the stability of large (mainlyun-reinforced) stope walls and crowns as well as on the stabilityof any exposed fill masses [1]. The performance of an open stopecan therefore be judged on the actual outcome versus the plannedoutcome, in terms of the final volume, tonnage and grade of thematerial extracted, and the timeliness of extraction, compared tothe planned design and schedule. Performance can be describedin a number of ways, from subjective qualitative terms toquantitative numbers, based on a number of parameters and/orphysical quantities. A number of quantitative measures of stopeperformance, such as ELOS [2], have been used in the past;however, some of these measures fail to adequately capturecertain geometrical aspects of over-break or under-break. Backanalysis of open stope performance is essential in the dilutioncontrol process, as an improved understanding of mechanismsallows one to check the validity of any assumptions and refinegeotechnical parameters used in the design process. A number ofnew shape descriptors are introduced to improve quantificationof over-break and under-break. The methodology is illustrated ondata from two case studies.2. New methodology2.1. Excavation geometry and performanceAn analysis of the shape of a resulting excavation surface relativeto its intended design can potentially provide useful informationabout the factors influencing excavation performance. For example,final excavation surfaces that are typified by extensive arcuateshaped over-break may indicate that the performance has beenaffected by significant rock mass failure, whereas prismatic orpolyhedral shaped over-break may potentially indicate more struc-turally controlled rock mass failure modes. Some further examplesof over-break geometries and potential failure modes and factorsaffecting performance are presented in Table 1.2.2. Geometrical assessment of stope performanceIn an attempt to determine the relative performance of stopes,one generally compares certain geometrical parameters of theover/under-break, such as volume, area or depth. Comparison ofthese parameters can be made on individual stope wall surfacesto ascertain whether there is any differential performancebetween walls. However, the use of such parameters alone doesnot necessarily provide an adequate characterisation of thegeometry of over/under-break. In evaluating the geometry ofover/under-break one needs to consider the following aspects:location, orientation, size and shape.The first two aspects of geometry are relatively simple toascertain. In this paper the size-and-shape aspects of over-breakare investigated with a number of quantitative measures pro-posed to describe these two geometrical aspects.2.3. Shape and sizeShape is one of the most difficult parameters to measure, as itmay be defined in a number of ways for various purposes, eachwith various degrees of precision [3]. The basic definition of‘‘shape’’ is provided by [4]; ‘‘Shape is all the geometrical informa-tion that remains when location, scale and rotation effects arefiltered out from an object.’’ Essentially this means that twogeometrical objects will have the same ‘‘shape’’ if, after beingrotated, translated and re-scaled, they match perfectly. Some-times, it is also necessary to see if geometrical objects of thesame ‘‘shape’’ are of different sizes. In this case, the definition ofContents lists available at ScienceDirectjournal homepage:www.elsevier.com/locate/ijrmms

Diffusion-Driven Looping Provides a Consistent Framework for Chromatin Organization

Chromatin folding inside the interphase nucleus of eukaryotic cells is done on multiple scales of length and time. Despite recent progress in understanding the folding motifs of chromatin, the higher-order structure still remains elusive. Various experimental studies reveal a tight connection between genome folding and function. Chromosomes fold into a confined subspace of the nucleus and form distinct territories. Chromatin looping seems to play a dominant role both in transcriptional regulation as well as in chromatin organization and has been assumed to be mediated by long-range interactions in many polymer models. However, it remains a crucial question which mechanisms are necessary to make two chromatin regions become co-located, i.e. have them in spatial proximity. We demonstrate that the formation of loops can be accomplished solely on the basis of diffusional motion. The probabilistic nature of temporary contacts mimics the effects of proteins, e.g. transcription factors, in the solvent. We establish testable quantitative predictions by deriving scale-independent measures for comparison to experimental data. In this Dynamic Loop (DL) model, the co-localization probability of distant elements is strongly increased compared to linear non-looping chains. The model correctly describes folding into a confined space as well as the experimentally observed cell-to-cell variation. Most importantly, at biological densities, model chromosomes occupy distinct territories showing less inter-chromosomal contacts than linear chains. Thus, dynamic diffusion-based looping, i.e. gene co-localization, provides a consistent framework for chromatin organization in eukaryotic interphase nuclei.

Morphometric variability of minicolumns in the striate cortex of Homo sapiens, Macaca mulatta, and Pan troglodytes

Radially oriented ensembles of neurons and their projections, termed minicolumns, are hypothesized to be the basic microcircuit of mammalian cerebral cortex. Minicolumns can be divided into a core and a peripheral neuropil space compartment. The core of minicolumns is constrained by the migratory path of pyramidal cells and their attendant radially oriented projections. Variation in minicolumnar morphometry and density is observed both within and across species. Using a scale-independent measure of variability in minicolumnar width (V(CW)), we demonstrated a significant increase in V(CW) in layers III-V of striate cortex in humans relative to macaques and chimpanzees. Despite changes in minicolumnar width (CW) across species, their core space (w) remained the same. Given that cellular elements and processes within the peripheral neuropil space of minicolumns are derived from assorted sources, cross-species differences in VCW may result from genetic and epigenetic influences acting primarily on this compartment of the minicolumn.

High-speed microfluidic differential manometer for cellular-scale hydrodynamics.

We propose a broadly applicable high-speed microfluidic approach for measuring dynamical pressure-drop variations along a micrometer-sized channel and illustrate the potential of the technique by presenting measurements of the additional pressure drop produced at the scale of individual flowing cells. The influence of drug-modified mechanical properties of the cell membrane is shown. Finally, single hemolysis events during flow are recorded simultaneously with the critical pressure drop for the rupture of the membrane. This scale-independent measurement approach can be applied to any dynamical process or event that changes the hydrodynamic resistance of micro- or nanochannels.

Two correlation patterns as indicators for underlying dynamics of complex systems

Two spatial correlation patterns, fixed-to-arbitrary and neighboring bin correlation patterns, are suggested. It is demonstrated that these patterns present scale-independent and distinguishable measures for correlated and uncorrelated random multiplicative cascade processes. Their application to very high multiplicity events in relativistic heavy ion collisions is discussed.

Quality of life in hereditary neuromuscular diseases.

The aim of the study is to evaluate different aspects in the quality of life (QoL) in a group of patients affected by hereditary neuromuscular disease. Forty-five consecutive outpatients (mean age 49.46 +/- 17.07 years, range 19-80 years) with hereditary neuromuscular disease underwent the Brooke scale and functional independent measure to assess the functional status, the Sickness Impact Profile (SIP) and Psychological General Well-Being Index (PGWBI), as a measure of the QoL. All patients had a poor QoL assessment with SIP. The higher disability level was not related to a worse QoL perception with the exception of the physical area. Females and patients above 49 years showed the worst QoL profile. The discomfort linked to the emotional and affective sphere, assessed with PGWBI, appeared low in the study sample. Therefore psychosocial aspects and economical and environmental factors may influence the QoL.

Three-dimensional visualization of lung blood flow heterogeneity based on fluorescent microsphere technique and fractal dimension: The Blood Flow Analysis System — BFA System

The heterogeneity of regional pulmonary blood flow (RPBF) can be assessed by fractal analysis. The fractal dimension (FD) is a scale-independent measure of spatial heterogeneity of blood flow. The relative dispersion (RD) is often used to obtain the heterogeneity of RPBF but it is influenced by the resolution of measurement. The Blood Flow Analysis (BFA) System was developed in Delphi to represent the three-dimensional structure of lung blood flow and calculates statistics of FD, RD, spatial correlation of neighbored tissue samples and shows histograms of blood flows at diverse time points during different experiments. The BFA System reads a text file with flows, measured with fluorescent microsphere technique, and constructs the lung anatomy with volumetric pixels showing the flows with a color schema. It is possible to rotate the lungs into two axis ( XY) and the statistics are shown with 3D graphics. The System maintains a database with data from various studies at same time. The BFA System was validated with four data sets from previous experiments. The BFA System has shown consistency and it is a new tool to help researchers during lung perfusion studies.

Satellite tracking of a fin whale (Balaenoptera physalus) in the north-western Mediterranean Sea and fractal analysis of its trajectory

Satellite tracking of whales was the aim of the ARGOCET program in the western Mediterranean Sea. With the tracking technology and the development of telemetry, we can study large mammals under natural conditions. In 1991, a satellite tracking during 42 days on a fin whale (Balaenoptera physalus) was obtained. The Argos system allowed us to know the location of this tagged fin whale 263 times. In this study, we can distinguish two kinds of movements: linear segments and tortuous segments with loops drawn in a clockwise direction. Such loops may be superficial oscillations of inertia due to the inertia of the water mass combined with earth's rotation. With this trial study, which is the best we have obtained, we can estimate the fractal dimension d of this trajectory at different observation scales. These d values seem to be scale-independent, so the fin whale path is fractal-like or scale-independent. Fractal dimension, which is a scale-independent measure, summarizes interactions between an organism and its ecosystem and depends on the heterogeneity of the whale's environment (exogeneous factors) and the whale's ability to perceive it (endogeneous factors). For the fin whale trajectory we calculated d = 1.03 +/−0.01 with the divider method. The aggregated distribution of available resources for the fin whale in the western Mediterranean Sea can explain this result close to 1. The heterogeneity of this food resources is not a `measured heterogeneity' but is a `functional heterogeneity'. The low fractal dimension also points to the low probability that the tagged fin whale and the zooplankton aggregates will meet in the western Mediterranean Sea so the fin whale must cover long straight lines from one patch of available zooplankton to another.

Does intensive rehabilitation improve the functional outcome of patients with traumatic brain injury? Interim result of a randomized controlled trial

To evaluate the effects of intensive rehabilitation on the functional outcome in patients with traumatic brain injury (TBI), we carried out a randomized controlled assessor-blind trial, comparing two groups of patients receiving different intensities of rehabilitation treatment (2 versus 4 h per day). Patients with moderate and severe TBI, aged from 12 to 65 years, were included. Glasgow Outcome Scale (GOS) and Functional Independent Measurement (FIM) were assessed monthly. The interim results of 36 cases showed that there was a trend of more patients in the study group achieving full FIM scores, and good GOS at 2 and 3 months, but the control group appeared to be catching up towards 6 months. Intensive rehabilitation may improve the early functional outcome of TBI patients. The interim results indicate that the study should be continued.

Application of statistical models for secondary data usage of the US Navy's Occupational Exposure Database (NOED).

Many organizations around the world have collected data related to individual worker exposures that are used to determine compliance with workplace standards. These data are often warehoused and thereafter rarely used as an information resource. Using appropriate groupings and analysis of OSHA data, Gómez showed that such stored data can provide additional insight on factors affecting occupational exposures. Using data from the Occupational Exposure Database of the United States Navy, the usefulness of statistical models for defining probabilities of exposure above permissible limits for observed work conditions is examined. Analyses have highlighted worker Similar Exposure Groups (SEGs) with potential for overexposure to asbestos and lead. In terms of grouping data, Rappaport et al. defined the Within-Between Lognormal Model, a scale-independent measure for quantifying between-worker variability within a selected worker group: (B)R.95 = exp[3.92s(sB)], representing the ratio of arithmetic mean exposures received by workers in the 97.5th and 2.5th percentiles. To help search for groups, the Proportional Odds Model, a generalization of the logistic model to ordinal data, can predict probabilities for group exposure above the Occupational Exposure Limit (OEL), or the Action Level (AL), which is one-half of the OEL. Worker SEGs have been identified for asbestos workers removing friable asbestos ((B)R.95 = 11.0) and nonfriable asbestos ((B)R.95 = 6.5); metal cleaning workers sandingspecialized equipment ((B)R.95 = 11.3), and workers at target shooting ranges cleaning up lead debris ((B)R.95 = 10). Estimated probabilities for the categories <AL, AL-OEL, and >OEL support current understanding of work processes examined. Differences in probability noted between tasks and levels of ventilation validate this method for evaluating other available workplace exposure determinants, and for predicting probability of membership in categories that may help further define worker exposure groups, and determinants of excessive exposures. Thus, analyses of retrospective exposure data can help identify work site and work practice factors for efficient targeting of remediation resources.