Price and volume effects around Islamic index revisions: the case of DJIM-GCC

PurposeThis study explores the price and trading volume effects around the quarterly Dow Jones Islamic Market-GCC index (DJIM-GCC) revisions and investigates whether these reactions are driven by firms' fundamentals or by investors' perception of ethical screening.Design/methodology/approachThe authors adopt an event study methodology to analyze the price and volume effects of Islamic indices redefinitions.FindingsThe results exhibit a positive (negative) price reaction for added (deleted) stocks. The authors also document an asymmetric volume response for index additions and deletions. The multivariate analysis of the cumulative abnormal returns reveals that the documented market reaction around Islamic index revisions is mainly related to the compliance attribution (withdrawal).Originality/valueThe approach allows to separate the market reaction arising from changes in firms' fundamentals from that induced by investors' perception of the attribution or withdrawal of a compliance certification. Moreover, the focus on the GCC region, where countries share the same cultural traits and perceive Islamic law identically excludes any social effect that would influence the market reaction due to cultural differences between countries.

Effect of Geometrical Parameters On Sensitivity And Volume Of Dual Octal Ring

Force transducer is one of the load cell which is used to measure force or weight, pressure etc. various types of transducers are manufacturing for various applications. But most of strain gauge type of transducer is used. In current research, optimization of octagonal type of force transducer design is carried out by maximizing sensitivity and minimizing the volume. Force transducer is analyze with the help of finite element method and find the critical parameters, its effect also as sensitivity and volume. Response surface methodology is used for experimental set up. For performance of all parameters analysis of variance is carried out and multi-objective optimization is also performed.

Credibility Assessment of a Subject-Specific Mathematical Model of Blood Volume Kinetics for Prediction of Physiological Response to Hemorrhagic Shock and Fluid Resuscitation

Subject-specific mathematical models for prediction of physiological parameters such as blood volume, cardiac output, and blood pressure in response to hemorrhage have been developed. In silico studies using these models may provide an effective tool to generate pre-clinical safety evidence for medical devices and help reduce the size and scope of animal studies that are performed prior to initiation of human trials. To achieve such a goal, the credibility of the mathematical model must be established for the purpose of pre-clinical in silico testing. In this work, the credibility of a subject-specific mathematical model of blood volume kinetics intended to predict blood volume response to hemorrhage and fluid resuscitation during fluid therapy was evaluated. A workflow was used in which: (i) the foundational properties of the mathematical model such as structural identifiability were evaluated; (ii) practical identifiability was evaluated both pre- and post-calibration, with the pre-calibration results used to determine an optimal splitting of experimental data into calibration and validation datasets; (iii) uncertainty in model parameters and the experimental uncertainty were quantified for each subject; and (iv) the uncertainty was propagated through the blood volume kinetics model and its predictive capability was evaluated via validation tests. The mathematical model was found to be structurally identifiable. Pre-calibration identifiability analysis led to splitting the 180 min of time series data per subject into 50 and 130 min calibration and validation windows, respectively. The average root mean squared error of the mathematical model was 12.6% using the calibration window of (0 min, 50 min). Practical identifiability was established post-calibration after fixing one of the parameters to a nominal value. In the validation tests, 82 and 75% of the subject-specific mathematical models were able to correctly predict blood volume response when predictive capability was evaluated at 180 min and at the time when amount of infused fluid equals fluid loss.

Modelling steady states and the transient response of debris-covered glaciers

Debris-covered glaciers are commonly found in alpine landscapes of high relief and play an increasingly important role in a warming climate. As a result of the insulating effect of supraglacial debris, their response to changes in climate is less direct and their dynamic behaviour more complex than for debris-free glaciers. Due to a lack of observations, here we use numerical modelling to explore the dynamic interactions between debris cover and geometry evolution for an idealized glacier over centennial timescales. The main goal of this study is to understand the effects of debris cover on the glacier's transient response. To do so, we use a numerical model that couples ice flow, debris transport, and its insulating effect on surface mass balance and thereby captures dynamic feedbacks that affect the volume and length evolution. In a second step we incorporate the effects of cryokarst features such as ice cliffs and supraglacial ponds on the dynamical behaviour. Our modelling indicates that thick debris cover delays both the volume response and especially the length response to a warming climate signal. Including debris dynamics therefore results in glaciers with extended debris-covered tongues and that tend to advance or stagnate in length in response to a fluctuating climate at century timescales and hence remember the cold periods more than the warm. However, when including even a relatively small amount of melt enhancing cryokarst features in the model, the length is more responsive to periods of warming and results in substantial mass loss and thinning on debris-covered tongues, as is also observed.

Dose-response relationships of intestinal organs and excessive mucus discharge after gynaecological radiotherapy

Background The study aims to determine possible dose-volume response relationships between the rectum, sigmoid colon and small intestine and the ‘excessive mucus discharge’ syndrome after pelvic radiotherapy for gynaecological cancer. Methods and materials From a larger cohort, 98 gynaecological cancer survivors were included in this study. These survivors, who were followed for 2 to 14 years, received external beam radiation therapy but not brachytherapy and not did not have stoma. Thirteen of the 98 developed excessive mucus discharge syndrome. Three self-assessed symptoms were weighted together to produce a score interpreted as ‘excessive mucus discharge’ syndrome based on the factor loadings from factor analysis. The dose-volume histograms (DVHs) for rectum, sigmoid colon, small intestine for each survivor were exported from the treatment planning systems. The dose-volume response relationships for excessive mucus discharge and each organ at risk were estimated by fitting the data to the Probit, RS, LKB and gEUD models. Results The small intestine was found to have steep dose-response curves, having estimated dose-response parameters: γ50: 1.28, 1.23, 1.32, D50: 61.6, 63.1, 60.2 for Probit, RS and LKB respectively. The sigmoid colon (AUC: 0.68) and the small intestine (AUC: 0.65) had the highest AUC values. For the small intestine, the DVHs for survivors with and without excessive mucus discharge were well separated for low to intermediate doses; this was not true for the sigmoid colon. Based on all results, we interpret the results for the small intestine to reflect a relevant link. Conclusion An association was found between the mean dose to the small intestine and the occurrence of ‘excessive mucus discharge’. When trying to reduce and even eliminate the incidence of ‘excessive mucus discharge’, it would be useful and important to separately delineate the small intestine and implement the dose-response estimations reported in the study.

Half-Brain Delineation for Prediction of Radiation-Induced Temporal Lobe Injury in Nasopharyngeal Carcinoma Receiving Intensity-Modulated Radiotherapy

PurposeTo investigate the role of half-brain delineation in the prediction of radiation-induced temporal lobe injury (TLI) in nasopharyngeal carcinoma (NPC) receiving intensity-modulated radiotherapy (IMRT).Methods and MaterialsA total of 220 NPC cases treated with IMRT and concurrent platinum-based chemotherapy were retrospectively analyzed. Dosimetric parameters of temporal lobes, half-brains, and brains included maximum dose (Dmax), doses covering certain volume (DV) from 0.03 to 20 cc and absolute volumes receiving specific dose (VD) from 40 to 80 Gy. Inter-structure variability was assessed by coefficients of variation (CV) and paired samples t-tests. Receiver operating characteristic curve (ROC) and Youden index were used for screening dosimetric parameters to predict TLI. Dose/volume response curve was calculated using the logistic dose/volume response model.ResultsCVs of brains, left/right half-brains, and left/right temporal lobes were 9.72%, 9.96%, 9.77%, 27.85%, and 28.34%, respectively. Each DV in temporal lobe was significantly smaller than that in half-brain (P < 0.001), and the reduction ranged from 3.10% to 45.98%. The area under the curve (AUC) of DV and VD showed an “increase-maximum-decline” behavior with a peak as the volume or dose increased. The maximal AUCs of DVs in brain, half-brain and temporal lobe were 0.808 (D2cc), 0.828 (D1.2cc) and 0.806 (D0.6cc), respectively, and the maximal AUCs of VDs were 0.818 (D75Gy), 0.834 (V72Gy) and 0.814 (V70Gy), respectively. The cutoffs of V70Gy (0.86 cc), V71Gy (0.72 cc), V72Gy (0.60 cc), and V73Gy (0.45 cc) in half-brain had better Youden index. TD5/5 and TD50/5 of D1.2cc were 58.7 and 80.0 Gy, respectively. The probability of TLI was higher than >13% when V72Gy>0 cc, and equal to 50% when V72Gy = 7.66 cc.ConclusionHalf-brain delineation is a convenient and stable method which could reduce contouring variation and could be used in NPC patients. D1.2cc and V72Gy of half-brain are feasible for TLI prediction model. The dose below 70 Gy may be relatively safe for half-brain. The cutoff points of V70–73Gy could be considered when the high dose is inevitable.