Measured Time Periods Research Articles

Improving Urban Air Quality Measurements by a Diffusion Charger Based Electrical Particle Sensors - A Field Study in Beijing, China

ABSTRACTHigh aerosol loadings contribute significantly to the air quality problems of Asian megacities. To address this, monitoring data for aerosol mass and number that is spatially and temoprally of high resolution is needed, while the cost of obtaining such data remains high. Here, we present a field study in a polluted megacity, Beijing, using a diffusion-chargebased electrical aerosol sensor, the Pegasor PPS-M, which is a robust and comparatively low-cost instrument for the monitoring of both aerosol mass and number simultaneously. We present data over several months in the year 2014, and for varying aerosol size distributions, and analyze the performance against particle number and mass (volume) measured using a wide range particle sizer (WPS) and beta-attenuation-based PM2.5 observations. We show that using a single trap voltage, the PPS-M correlates well with particle mass, but not so well with particle number due to the variability in particle size distributions. However, the instrument response to number was improved by running the instrument with a variable trap voltage, and using the ratio of the different signals to gain information on the particle average volume. With this method, we were able to improve the correlation of the PPS-M; with the observed particle number from R = 0.14 to R = 0.72 for the measurement time period. Altogether, the PPS-M instrument displayed robustness and low maintenance requirements, and it showed good correlation with the other instruments in this study.

Volumetric Three-Dimensional Wind Measurement Using a Single Mobile-Based LiDAR

A novel approach to measure the wind flow field in a utility-scale wind farm is described. The measurement technique uses a mobile, three-dimensional scanning LiDAR system to make successive measurements of the line-of-sight (LOS) wind speed from three different positions; from these measurements, the time-averaged three-dimensional wind velocity vectors are reconstructed. The scanning LiDAR system is installed in a custom-built vehicle in order to enable measurements of the three-dimensional wind flow field over a footprint that is larger than with a stationary scanning LiDAR system. At a given location, multiple series of plan position indicator (PPI) and velocity azimuthal display scans are made to average out turbulent fluctuations; this series is repeated at different locations across the wind farm. The limited duration of the total measurement time period yields measurements of the three-dimensional wind flow field that are unaffected by diurnal events. The approach of this novel measurement technique is first validated by comparisons to a meteorological mast and SODAR at a meteorological observatory. Then, the measurement technique is used to characterize the wake flows in two utility-scale wind farms: one in complex terrain and the other in flat terrain. The three-dimensional characteristics of the wakes are described in the measurements, and it is observed that in complex terrain the wake has a shorter downstream extent than in flat terrain. A maximum deficit in the wind speed of 20–25% is observed in the wake. The location of the maximum deficit migrates upward as the wake evolves; this upward migration is associated with an upward pitching of the wake flow. A comparison of the measurements to a semi-empirical wake model illustrates how the measurements, at full-scale Reynolds numbers, can support further development of wake models.

Self-reported sunscreen use and urinary benzophenone-3 concentrations in the United States: NHANES 2003–2006 and 2009–2012

BackgroundSunscreens protect against skin cancer and other harmful effects of solar ultraviolet radiation (UVR). Epidemiologic and public health surveys often rely on self-reported sunscreen use to estimate sun exposure and avoidance, but questions remain about the validity of self-reports. Benzophenone-3 (BP-3), a common sunscreen ingredient, can be detected in the urine. Prior studies suggest that BP-3 concentrations increase after application of sunscreen. ObjectivesThe goal of this study was to assess the validity of self-reported frequency of sunscreen use in relation to urinary BP-3 concentrations in a representative sample of the general US population, including in sub-groups defined by age, sex and race/ethnicity. MethodsTo assess the relationship between categorical self-reported sunscreen use and creatinine-corrected urinary BP-3 concentrations, we conducted a linear regression adjusted for age, sex, race/ethnicity, six-month time period, body mass index, education, and sun avoidance behaviors. We tested for effect modification by age, sex, ethnicity and time period of measurement using multiplicative interaction terms and a F test. ResultsBP-3 was positively associated with self-reported frequency of sunscreen use across all ages, sexes, race/ethnicities, and time periods. Crude and multivariate adjusted models were all statistically significant. R-square was relatively low for all models, ranging from 0.15 to 0.43. ConclusionsUrinary BP-3 is positively associated with self-reported frequency of sunscreen use in the general US population, even in groups with overall low sunscreen use. These results suggest that self-report is a valid, although weak, way of assessing relative frequencies of sunscreen usage in a population-based study.

Effects of dietary corticosterone on yolk colors and eggshell quality in laying hens.

The objective of this study was to investigate the effects of dietary corticosterone on egg quality. For 2 weeks hens received either control or experimental diet containing corticosterone at 30 mg/kg diet. Feed intake and egg production were monitored daily, and body weight measured weekly. Egg weights and egg quality were measured daily. Corticosterone treatment resulted in a remarkable increase in feed intake and sharp decrease in egg production compared with control (p<0.05) whereas body weight remained unchanged. Decreased albumen height, but no changes in egg weight, led to decreased Haugh unit (p<0.05). Corticosterone caused elevated eggshell thickness (p<0.05) without altering weight and strength, suggesting possible changes in shell structure. Yolk color and redness were increased by corticosterone (p<0.05) but lightness and yellowness were either not changed or inconsistent over the time period of measurements. Increased concentrations in plasma were also found for corticosterone, glucose, cholesterol, creatinine, uric acid, albumin, aspartate aminotransferase, creatine kinase, lactate dehydrogenase, total protein, and amylase (p<0.05), suggesting that corticosterone increased protein breakdown, renal dysfunctions and pancreatitis. Together, the current results imply that dietary corticosterone affects egg quality such as yolk colors and shell thickness, in addition to its effects on feed intake and egg production.

Impacto do anestesiologista em treinamento sobre as pressões do manguito de máscara laríngea e incidência de eventos adversos

ObjectiveWe have planned to evaluate the laryngeal mask cuff pressures (LMcp) inflated by anesthesia workers of several seniority, without using manometer. Methods180 patients scheduled to have short duration surgery with laryngeal mask were included in the study. Five anesthesia specialists (Group S), 10 residents (Group R) and 6 technicians (Group T) inflated the LMc; thereafter LMcp were measured with pressure manometer. Participants have repeated this practice in at least five different cases. LMcp higher than 60cm H2O at the initial placement or intraoperative period were adjusted to normal range. Sore throat was questioned postoperatively. Groups were compared in terms of mean LMcp and occupational experience. ResultsAt the settlement of LM, LMcp pressures within the normal range were determined in 26 (14.4%) cases. Mean LMcp after LM placement in Group S, R and T were 101.2±14.0, 104.3±20.5cm H2O and 105.2±18.4cm H2O respectively (p>0.05). Mean LMcp values in all measurement time periods within the groups were above the normal limit (60cm H2O). When groups were compared in terms of LMcp, no difference has been found among pressure values. Occupational experience was 14.2±3.9; 3.3±1.1 and 6.6±3.8 years for specialists, residents and technicians respectively and measured pressure values were not different in regard of occupational experience. Seven (3.9%) patients had sore throat at the 24th hour interview. ConclusionConsidering lower possibility of normal adjustment of LMcp and ineffectiveness of occupational experience to obtain normal pressure values, it is suitable that all anesthesia practitioners should adjust LMcp with manometer.

Measurement of Customer Loyalty Towards Service Providers: a Conceptual Framework

The increasing turbulence of business environment and the demand to gain a long-term competitive advantage has incited the research of the relevant issue concerning customer loyalty in the context of services sector. In order to formulate the conceptual framework of objective measurement of customer loyalty to service providers the dimensions of customer loyalty have been analyzed; suggestions to apply behavioral loyalty dimension that is considered to be sufficiently objective, practical and informative were made. The measurement of customer loyalty through the components of this concept, i.e. frequency of purchases and value of purchases, is seen as universal in the aspect of data accessibility. Considering the situations of the accessibility of the data concerning the customers' purchases frequency and value of purchases, the following alternatives of the measurement of customer loyalty in the context of services were suggested: 1) the statistical data; 2) the data of marketing researches / analogy; 2) the assessment of loyalty drivers / questionnaire survey. The provided sequence of the measurement of customer loyalty to service providers is as follows: the estimation of the significance of loyalty components, the definition of the time period of loyalty measurement, the identification of loyalty drivers.

A constrained wavelet smoother for pathway identification tasks in systems biology

Metabolic time series data are being generated with increasing frequency, because they contain enormous information about the pathway from which the metabolites derive. This information is not directly evident, though, and must be extracted with advanced computational means. One typical step of this extraction is the estimation of slopes of the time courses from the data. Since the data are almost always noisy, and the noise is typically amplified in the slopes, this step can become a critical bottleneck. Several smoothers have been proposed in the literature for this purpose, but they all face the potential problem that smoothed time series data no longer correspond to a system that conserves mass throughout the measurement time period. To counteract this issue, we are proposing here a smoother that is based on wavelets and, through an iterative process, converges to a mass-conserving, smooth representation of the metabolic data. The degree of smoothness is user defined. We demonstrate the method with some didactic examples and with the analysis of actual measurements characterizing the glycolytic pathway in the dairy bacterium Lactococcus lactis. MATLAB code for the constrained smoother is available as a Supplement.

Evaluation of the performance of a particle concentrator for online instrumentation

Abstract. The performance of the miniature Versatile Aerosol Concentration Enrichment System (m-VACES; Geller et al., 2005) was investigated in laboratory and field studies using online instruments. Laboratory tests focused on the behavior of monodisperse ammonium sulfate (AS) or dioctyl sebacate (DOS) particles in the m-VACES measured with the aerodynamic particle sizer (APS) and scanning mobility particle sizer (SMPS). The ambient measurements were conducted at an urban site in Helsinki, Finland, where the operation of the m-VACES was explored in conjunction with a Soot Particle Aerosol Mass Spectrometer (SP-AMS) in addition to the SMPS. In laboratory tests, the growth of particles in water vapor produced a stable droplet size distribution independent of the original particle size. However, when the droplets were dried with the goal of measuring the original size distribution, a shift to larger particles was observed for small particle sizes (up to ~ 200 nm in mobility diameter). That growth was probably caused by water-soluble organic compounds absorbed on the water droplets from the gas phase, but not evaporated in the drying phase. In ambient measurements, a similar enrichment was observed for nitrate and sulfate in the m-VACES whereas the presence of acidic ambient particles affected the enrichment of ammonium. Gaseous ammonia was likely to be absorbed on acidic particles in the m-VACES, neutralizing the aerosol. For organics, the enrichment efficiency was comparable with sulfate and nitrate but a small positive artifact for hydrocarbons and nitrogen-containing organic compounds was noticed. Ambient and concentrated organic aerosol (OA) was analyzed further with positive matrix factorization (PMF). A three-factor solution was chosen for both of the data sets but the factors were slightly different for the ambient and concentrated OA, however, the data set used for the PMF analysis was limited in size (3 days) and therefore had substantial uncertainty. Overall, the operation of the m-VACES was not found to lead to any severe sampling artifacts. The effect of acidity could be an issue in locations where the aerosol is acidic, however, in those cases the use of a denuder (which was not used in this study) is recommended. Further ambient tests are needed for the characterization of the m-VACES as the time period for the ambient measurements was only 5 days in this study. Especially for OA additional tests are important as the chemical properties of organics can differ widely depending on time and location.

Noise Analysis of Magnetic Sensors Using Allan Variance

The article deals with the noise analysis of magnetic sensors using Allan variance. In comparison with the standard variance, based on the variations around the average value, Allan variance provides a measure of the behavior of the variability of a quantity as it is averaged over di erent measurement time periods, which results in a better convergence and the possibility to distinguish types of noise directly. A signi cant advantage of this method is that there is no need of any transformations and according to the IEEE recommendation the Allan variance approach is the preferred method for stochastic error identi cation and the noise type determination in inertial sensors (accelerometers and gyroscopes). Considering that magnetic sensors become even more often a part of inertial measurements units, the goal of this article is to prove that the method using the Allan variance analysis can be very successfully applied also for noise analysis in magnetic sensors.

Implementation and preliminary outcomes of a comprehensive oral chemotherapy management clinic.

Improved outcomes achieved by an oral chemotherapy management (OCM) clinic, including a reduction in the need for medication-related interventions, are reported. A retrospective observational cohort study was conducted to assess the effectiveness of an OCM clinic providing comprehensive medication therapy management (MTM) services, including education on various oral chemotherapy agents, concurrent medications, and symptom management, as well as insurance assistance. Patient demographics, self-rated depression scores, and data on concurrent medication use, types of interventions, and intervention outcomes were collected at baseline and at follow-up visits for up to three months. Thirty clinic patients (9 men and 21 women with a mean age of 64.5 years) were evaluated; the majority had advanced-stage cancer and no live-in caregiver. On average, the patients had 2.8 comorbid conditions, including hypertension (43%), chronic pain (43%), and diabetes (37%), and were taking 12.7 concurrent medications (range, 3-26). In general, OCM clinic interventions in five categories (adverse events, adherence, drug interactions, medication errors, and symptom management) decreased during the measured time periods. About 70% of OCM clinic interventions were associated with positive outcomes (i.e., complete resolution of event or improved response to therapy), with 67% and 36% of interventions resulting in potential cost avoidance and cost savings, respectively. Rates of optimal oral chemotherapy adherence and persistence were estimated at 70%. An OCM clinic with comprehensive MTM services was effective in delivering early interventions, resulting in decreased rates of adverse effects, nonadherence, drug interactions, and medication errors over time.

Validation and feasibility of a caloric expenditure measuring device in women with early-stage breast cancer.

The purpose of this study is to validate the Bodybugg (BB), a caloric expenditure measuring device, in breast cancer patients undergoing adjuvant and neoadjuvant chemotherapy for early-stage breast cancer. Twenty-five women with stages I-III breast cancer who wereto receive adjuvant dose-dense doxorubicin/cyclophosphamide were recruited. Participants were asked to wear the BB and record activity logs for seven pretreatment days (prior to commencing chemotherapy) and seven posttreatment days (upon completing cycle 4 of chemotherapy). The BB's caloric expenditure measurements were used to calculate metabolic equivalent (MET) values of patients' recorded activities. BB-calculated METs were compared with matching METs from the 2011 Compendium of Physical Activities Tracking Guide to assess accuracy of the device. The overall patient sample wore the device for an average of 5.32 (SD 1.75) pre- and 4.88 (SD 2.01) posttreatment days. The mean pairwise difference between BB and Compendium METs was 0.043 (SD 0.77) for 308 pretreatment activities recorded by 12 patients and 0.065 (SD 0.61) for 108 posttreatment activities recorded by 6 patients, indicating close to zero bias between the BB's and Compendium's measurements. Hierarchical linear modeling showed that Compendium METs strongly predict for BB METs (P < 0.00001). The BB is feasible to use in study designs involving defined time periods of measurement and provides accurate and objective measurements of caloric expenditure in breast cancer patients.

Diffusion abnormalities of the corpus callosum in patients receiving bevacizumab for malignant brain tumors: suspected treatment toxicity

Bevacizumab has been reported to cause diffusion restriction in the tumor bed of patients with malignant gliomas. This study evaluated prolonged diffusion restriction, in the corpus callosum (CC), of patients with malignant brain tumors treated with bevacizumab. We retrospectively reviewed our database of patients treated with bevacizumab for malignant brain tumors looking for those with restricted diffusion in the CC. CC ADC ratio measurements were obtained prior to and following treatment. Correlation was made with biopsy (n=3) and MR perfusion (n=7) and PET (n=4). The temporal evolution of these changes relative to therapy was examined with mixed effects regression analysis. Nine patients (eight malignant gliomas, one malignant meningioma) out of 146 patients were found to have developed areas of diffusion restriction in the CC. These areas tended to enlarge and coalesce over serial MRIs and persisted for up to 22months. Hypoperfusion was demonstrated in MR perfusion in 7/7. PET was hypometabolic in all 4. Biopsy of the CC showed no tumor in 3/3. ADC ratio measurements indicated a significant overall effect of time (F(16,60)=11.2; p<0.0001), consistent with persistent diffusion restriction over the measured time periods. Bevacizumab causes prolonged diffusion restriction in the CC. The negative MR perfusion, FDG PET and histopathology suggest this is a toxicity of bevacizumab and not active tumor. Awareness of these changes can assist in patient care.

A Controlled Quality Improvement Trial to Reduce the Use of Physical Restraints in Older Hospitalized Adults

To implement and evaluate an evidence-informed multicomponent strategy to reduce physical restraint use in older adults admitted to acute care medical units. Stepped-wedge trial. Four acute care medical units in Calgary, Alberta, over a 4-month time period. Data were collected from individuals aged 65 and older present on the study units during monthly restraint audits. Development of opinion leaders among the nursing leadership, education and training of physicians and unit nurses, and implementation of least restraint rounds. The primary outcome was rate of restraint use as determined from walk-around audits. Secondary outcomes included number of physician orders for physical restraints on the electronic medical record and fall reports. Thirteen percent to 27% of individuals were being restrained on the medical units before the intervention, with the vast majority of restraints being bed rails. This decreased to 7% to 14% after the intervention. The intervention resulted in a statistically significant reduction in restraint use measured in the early mornings (P = .01), and this trend continued after adjusting for unit and month (P = .06). Similarly, the rate of restraint use trended down at all other measured time periods but was not statistically significant. A limited number of individuals had an order for physical restraint within their electronic medical record (3% before, 2% after the intervention). The median number of monthly fall reports did not change (three before, three after; P = .60). A multicomponent team-focused quality improvement intervention has the potential to decrease the use of physical restraints in older hospitalized adults.

Measurements of the evaporation and hygroscopic response of single fine-mode aerosol particles using a Bessel beam optical trap

A single horizontally-propagating zeroth order Bessel laser beam with a counter-propagating gas flow was used to confine single fine-mode aerosol particles over extended periods of time, during which process measurements were performed. Particle sizes were measured by the analysis of the angular variation of light scattered at 532 nm by a particle in the Bessel beam, using either a probe beam at 405 nm or 633 nm. The vapour pressures of glycerol and 1,2,6-hexanetriol particles were determined to be 7.5 ± 2.6 mPa and 0.20 ± 0.02 mPa respectively. The lower volatility of hexanetriol allowed better definition of the trapping environment relative humidity profile over the measurement time period, thus higher precision measurements were obtained compared to those for glycerol. The size evolution of a hexanetriol particle, as well as its refractive index at wavelengths 532 nm and 405 nm, were determined by modelling its position along the Bessel beam propagation length while collecting phase functions with the 405 nm probe beam. Measurements of the hygroscopic growth of sodium chloride and ammonium sulfate have been performed on particles as small as 350 nm in radius, with growth curves well described by widely used equilibrium state models. These are the smallest particles for which single-particle hygroscopicity has been measured and represent the first measurements of hygroscopicity on fine mode and near-accumulation mode aerosols, the size regimes bearing the most atmospheric relevance in terms of loading, light extinction and scattering. Finally, the technique is contrasted with other single particle and ensemble methods, and limitations are assessed.

Study on sensitivity improving of fiber Bragg grating based pH sensor

The key factor of the sensitivity in the FBG-based pH sensor is analyzed in detail. A multi-thin-layer structure of the gel coated cover was proposed and implemented with a special process. The sensors with the coated thickness of 420 μm, 500 μm, and 580 μm were built up, respectively. The corresponding spectral shifts of 0.08 nm, 0.13 nm, and 0.22 nm were detected when the pH sensors were soaked in the pH value of 3–9. Meanwhile, the sensor with the gel layer thickness of 580 μm was measured in the optimum measurement time period with the pH value changing from 3–12, in which the detected sensitivity of 52 pm/pH was achieved in the pH range of 6–12.

Impact of the practising anesthesiologist team member on the laryngeal mask cuff pressures and adverse event rate

ObjectiveWe have planned to evaluate the laryngeal mask cuff pressures (LMcp) inflated by anesthesia workers of several seniority, without using manometer. Methods180 patients scheduled to have short duration surgery with laryngeal mask were included in the study. Five anesthesia specialists (Group S), 10 residents (Group R) and 6 technicians (Group T) inflated the LMc; thereafter LMcp were measured with pressure manometer. Participants have repeated this practice in at least five different cases. LMcp higher than 60cm H2O at the initial placement or intraoperative period were adjusted to normal range. Sore throat was questioned postoperatively. Groups were compared in terms of mean LMcp and occupational experience. ResultsAt the settlement of LM, LMcp pressures within the normal range were determined in 26 (14.4%) cases. Mean LMcp after LM placement in Group S, R and T were 101.2±14.0, 104.3±20.5cm H2O and 105.2±18.4cm H2O respectively (p>0.05). Mean LMcp values in all measurement time periods within the groups were above the normal limit (60cm H2O). When groups were compared in terms of LMcp, no difference has been found among pressure values. Occupational experience was 14.2±3.9; 3.3±1.1 and 6.6±3.8 years for specialists, residents and technicians respectively and measured pressure values were not different in regard of occupational experience. Seven (3.9%) patients had sore throat at the 24th hour interview. ConclusionConsidering lower possibility of normal adjustment of LMcp and ineffectiveness of occupational experience to obtain normal pressure values, it is suitable that all anesthesia practitioners should adjust LMcp with manometer.

Weighted objective function selector algorithm for parameter estimation of SVAT models with remote sensing data

(1) The objective function of the inverse problem in Soil-Vegetation-Atmosphere-Transfer (SVAT) models can be expressed as the aggregation of two criteria, accounting for the uncertainties of surface soil moisture (� ) and evapotranspiration (ET), retrieved from remote sensing (RS). In this context, we formulate a Weighted-Objective-Function (WOF) with respect to model effective soil hydraulic parameters, comprising of two components for � and ET, respectively, and a dimensionless coefficient w. Given that the sensitivity ofis increased by omitting the periods when soil moisture decoupling occurs, we also introduce within the WOF a threshold, � d, which outlines the decoupling of the surface and root-zone moisture. The optimal values of w andd are determined by using a novel framework, weighted objective function selector algorithm (WOFSA). This performs numerical experiments, assuming known reference conditions. In particular, it solves the inverse problem for different sets ofand ET, considering the uncertainties of retrieving them from RS, and then runs the hydrological model to obtain the simulated water fluxes and their residuals, DWF, against the reference responses. It estimates the two unknown variables, w andd, by maximizing the linear correlation between the WOF and maximum DWF. The framework is tested using a modified Soil-Water-Atmosphere-Plant (SWAP) model, under 22 contrasting hydroclimatic scenarios. It is shown that for each texture class, w can be expressed as function of the averageand ET-fraction, while that for all scenariosd can be modeled as function of the average � , average ET, and standard deviation of ET. Based on the outcomes of this study, we also provide recommendations on the most suitable time period for soil moisture measurements for capturing its dynamics and thresholds. Finally, we propose the implementation of WOFSA within multiobjective calibration, as a generalized tool for recognizing robust solutions from the Pareto front.

Thermoresponsive Dendronized Polyprolines via the “Grafting to” Route

The first and second generations of dendronized polyprolines P3G1, P3G2, and P4G1 are prepared via the "grafting to" route, and their thermoresponsive properties and helical conformations investigated. High molar masses of polyproline main chains carrying azido groups are achieved first by polycondensation of peptide precursors through activated ester strategy. Oligoethylene glycol dendrons cored with alkyne are then attached onto the main chains through click reaction. These polymers are found to be thermoresponsive. Circular dichroism spectroscopy investigation indicates, in contrast to P3G2 and P4G1 which adopt the expected PPII conformation in aqueous conditions, P3G1 prefers to adopt PPI helical conformation, and this conformation is stable within the measured time period and temperature range.

Behavioural changes in the flour beetleTribolium confusuminfected with the spirurid nematodeProtospirura muricola

We examined changes to the behaviour of flour beetles, Tribolium confusum, infected with the rodent stomach worm, the spirurid Protospirura muricola, in the context of the 'Behavioural Manipulation Hypothesis'. Trobolium confusum infected with the third-stage infective larvae of P. muricola showed consistently altered patterns of behaviour. Relative to uninfected beetles, over a measured time period, beetles infected with P. muricola were likely to move over a shorter distance, when moving their speed of movement was slower, they were more likely to stay in the illuminated area of their environment, more likely to emerge from darkened areas into the illuminated areas, and their longevity was significantly shortened. The changes in behaviour, as reflected in effects on speed of movement, were only evident among beetles that actually harboured infective cysts and not among those carrying younger infections when the larvae within their haemocoels would have been at an earlier stage of development and not yet capable of infecting the definitive murine hosts. We discuss whether these changes would have made the beetles more susceptible to predation by rodents, and specifically by the omnivorous eastern spiny mouse, Acomys dimidiatus, the natural definitive host of this parasite in Egypt, from where the P. muricola isolate originated, and whether they support the Behavioural Manipulation Hypothesis or reflect parasite-induced pathology.

Progress and regression group performance in data envelopment analysis (DEA): An application of productivity Malmquist index

In this paper, we extend the work of Camanho and Dyson (2006, 26:35-49) into a group of Malmquist productivity index for two time periods of measurement, based on the Malmquist index to enable the decision making units’ internal efficiencies from those associated with their group characteristics. We construct an index reflecting the relative performance groups in two time periods, which can be decomposed into two indices, first for the comparison of efficiency changing and another index for comparison of technological change. We provide a computational method for extension of the Malmquist index group A in relation to group B of time t to time t+1. The utilization of the proposed approach is demonstrated with an illustrative example. Key words: Data envelopment analysis (DEA), Malmquist productivity index, group efficiency.