Split-sample Technique Research Articles

Effect of glutathione on the quality of frozen buck semen

Ejaculates (30) collected twice weekly from five Beetal bucks were used to study the effect of addition of 0 (control), 4 mM, 6 mM and 8 mM glutathione on the quality of frozen Beetal buck semen by split sample technique. After removal of seminal plasma, the semen was primarily extended with Tris extender (1: 5) considering the volume of semen prior to removal of seminal plasma and then split into 4 parts and finally extended with equal volume of Tris extender that rose the extension rate to 1: 10. The mean percentage of sperm motility, live sperm, live intact acrosome, HOST-reacted sperm was significantly higher in Tris extender containing 4 mM glutathione than that containing 6 mM, 8 mM glutathione and control. The release of ALT and AST from post-thaw spermatozoa was also the lowest in semen containing 4mM concentration of glutathione. Based on post-thaw sperm motility, live sperm, live intact acrosome, HOST-reacted sperm, and ALT and AST release, addition of 4 mM glutathione in Tris extender was superior to 6 mM, 8 mM and 0 mM (control). It was concluded that glutathione at 4 mM could be used as an antioxidant in Tris for cryopreservation of Beetal buck semen which could provide a better environment in protecting the functional capacity of spermatozoa.

Perioperative Respiratory Adverse Events in Pediatric Ambulatory Anesthesia: Development and Validation of a Risk Prediction Tool.

Perioperative respiratory adverse events (PRAEs) are the most common cause of serious adverse events in children receiving anesthesia. Our primary aim of this study was to develop and validate a risk prediction tool for the occurrence of PRAE from the onset of anesthesia induction until discharge from the postanesthesia care unit in children younger than 18 years undergoing elective ambulatory anesthesia for surgery and radiology. The incidence of PRAE was studied. We analyzed data from 19,059 patients from our department's quality improvement database. The predictor variables were age, sex, ASA physical status, morbid obesity, preexisting pulmonary disorder, preexisting neurologic disorder, and location of ambulatory anesthesia (surgery or radiology). Composite PRAE was defined as the presence of any 1 of the following events: intraoperative bronchospasm, intraoperative laryngospasm, postoperative apnea, postoperative laryngospasm, postoperative bronchospasm, or postoperative prolonged oxygen requirement. Development and validation of the risk prediction tool for PRAE were performed using a split sampling technique to split the database into 2 independent cohorts based on the year when the patient received ambulatory anesthesia for surgery and radiology using logistic regression. A risk score was developed based on the regression coefficients from the validation tool. The performance of the risk prediction tool was assessed by using tests of discrimination and calibration. The overall incidence of composite PRAE was 2.8%. The derivation cohort included 8904 patients, and the validation cohort included 10,155 patients. The risk of PRAE was 3.9% in the development cohort and 1.8% in the validation cohort. Age ≤ 3 years (versus >3 years), ASA physical status II or III (versus ASA physical status I), morbid obesity, preexisting pulmonary disorder, and surgery (versus radiology) significantly predicted the occurrence of PRAE in a multivariable logistic regression model. A risk score in the range of 0 to 3 was assigned to each significant variable in the logistic regression model, and final score for all risk factors ranged from 0 to 11. A cutoff score of 4 was derived from a receiver operating characteristic curve to determine the high-risk category. The model C-statistic and the corresponding SE for the derivation and validation cohort was 0.64 ± 0.01 and 0.63 ± 0.02, respectively. Sensitivity and SE of the risk prediction tool to identify children at risk for PRAE was 77.6 ± 0.02 in the derivation cohort and 76.2 ± 0.03 in the validation cohort. The risk tool developed and validated from our study cohort identified 5 risk factors: age ≤ 3 years (versus >3 years), ASA physical status II and III (versus ASA physical status I), morbid obesity, preexisting pulmonary disorder, and surgery (versus radiology) for PRAE. This tool can be used to provide an individual risk score for each patient to predict the risk of PRAE in the preoperative period.

Manual Liquid Based Cytology in Diagnosis of Gynecologic Pathology

Abnormal uterine bleeding (AUB) is a commonly encountered complaint in gynecology department. Endometrial cancer is the fourth most common malignancy in women and the most frequent gynecological cancer in developed countries. With 5,28, 000 new cases every year, cervical cancer is the fourth most common cancer affecting women worldwide, after breast, colorectal, and lung cancers. Though the cytological examination has been the mainstay for early detection of cervical cancer, and found to be useful in detection of endometrial cancer, its widespread use has not been possible in the developing countries due to paucity of resources, man power and other facilities Its sensitivity reduces to less than 50% when there is presence of obscuring blood, inflammation or thick areas of overlapping epithelial cells. Manual Liquid Based Cytology (MLBC) is a cost effective technique that enables cells to be suspended in a monolayer and thus improve detection of precursor lesions and specimen adequacy. The residual sample can be used for other tests like Cell block and immunocytochemistry. <b>Objectives </b>: 1. To improve the diagnosis of gynecological cancers by a method called as Manual Liquid Based Cytology (MLBC). 2. To study a cost effective method of studying both endometrial and cervical cancer with help of ancillary techniques like cellblock, immunocytochemistry 3To compare the findings between conventional pap smear (CPS) and MLBC in detection of gynecological conditions of endometrium and cervix. <b>Methodology </b>: Samples were collected using Ayres spatula by split sample technique from transformation zone of cervix which included outpatients of gynecology dept. The women were aged between 20-60 years, 82 cases with bleeding history were taken to study endometrial pathology, while 100 cases of white discharge per vagina were selected to study the cervix. 60 cases were later subjected to ancillary studies like cellblock with Immunocytochemistry. Histopathological correlation was done for cases wherever possible. <b>Results </b>: The study on endometruim showed MLBC is more sensitive and specific than CPS in diagnosis of malignant lesions. The contingency coefficient for LBC/Histopathology V/s CPS/Histopathology was 0.572 V/s 0.556. It was observed for cervical lesion that increased detection rate was 150% for low grade intraepithelial lesion. The Positive predictive value for diagnosing neoplastic lesions on cell blocks was 75%, while Concordance Rate of CB/HistopathologyVs CPS/Histopathology was 74% vs. 54%. <b>Conclusion </b>: MLBC is a cost effective method for detections of cancerous lesions of endometruim and cervix.

Effect of Different Glycerol Levels on Quality of Frozen Semen of Mizo Local Boar

A total of 24 ejaculates were obtained from 3 Mizo local boars (Zovawk), were used by split sample technique for evaluating the effect of four glycerol levels on quality of semen extended with Lactose egg yolk glycerol (LEYG) extender at equilibration and after freezing. The sperm motility at equilibration and after freezing was significantly higher (P<0.01) for 3 percent glycerol levels, than for 2 and 4 percent glycerol levels. The live sperm at equilibration and after freezing was significantly higher (P<0.01) for 3 percent glycerol levels than for 2 and 4 percent glycerol levels, and for 2 percent than for 3 percent glycerol level. The Hypo Osmotic Sperm Swelling Test (HOSST) reacted spermatozoa at equilibration and after freezing was significantly (P<0.01) higher for 3 percent glycerol levels, than for 2 and 4 percent glycerol levels, and for 2 percent than for 3 percent glycerol level. The acrosomal integrity at equilibration and after freezing was significantly (P<0.01) higher for 3 percent glycerol levels, than for 2 and 4 percent glycerol levels, and for 2 percent than for 3 percent glycerol level. In conclusion, preservation of boar semen in LEYG extender using 3 percent glycerol found to be superior.

Effect of butylated hydroxy toluene on the quality of frozen goat semen

Ejaculates (40) collected from 5 Beetal bucks twice weekly were used to study the effect of 0 (control), 150, 200 and 300 μM butylated hydroxy toluene (BHT) on the quality of frozen semen by split sample technique. After removal of the seminal plasma, the semen was primarily extended with Tris extender (1: 5) considering the volume of semen prior to removal of seminal plasma and then split into four parts and finally extended with equal volume of Tris extender containing 0 (control), 300, 400 and 600 μM BHT. Consequent upon addition of equal volumes of Tris extender the rate of extension of semen rose to 1: 10 and eventual concentration of BHT in the extender was 0, 150, 200 and 300 μM. The extended semen was cooled gradually to 5°C @ 1°C/3 min and equilibrated in the cold handling cabinet for 4 h at 5°C. The extended semen was filled in French mini straws (0.25 ml) and polyvinyl alcohol powder of different colours were used for sealing the extended semen for identification of semen of different bucks processed with different concentrations of BHT. The freezing of semen was done by rapid horizontal vapour freezing technique using liquid nitrogen. The mean percent post thaw sperm motility, live sperm, live intact acrosome and HOST-reacted sperm were significantly higher in the extender with 200 μM BHT than with 150, 300 μM BHT and control. The release of ALT and AST from post thaw spermatozoa was also the lowest (33.75 ± 0.17 and 221.61 ± 0.73 U/L respectively) in the extender containing 200 μM BHT. Based on sperm motility, live sperm, live intact acrosome, HOST-reacted sperm, and ALT and AST release, 200 μM BHT in Tris extender was superior to 0, 150, and 300 μM BHT in freezing Beetal buck semen. It was concluded that BHT at 200 μM provided a better protection to the functional capacity of buck spermatozoa for cryopreservation.

Prognostic models in traumatic brain injury

BackgroundPrognostic models are important tools for heterogeneity adjustment in traumatic brain injury (TBI). Prognoses after TBI have been particularly challenging to predict, with limited availability of robust prognostic models. TBI patients are by definition trauma patients, and often treated in the intensive care unit (ICU). Several prognostic models for ICU and trauma patients have been developed, although their applicability in patients with TBI is uncertain. Recently, however, some new prognostic models specifically designed for patients with TBI were introduced. Still, the optimal type of prognostic model in TBI remains unknown.AimThis aims to investigate the applicability of different types of prognostic models in patients with TBI and to develop novel models with enhanced performance to previous models, focusing on long‐ term outcome prediction.MethodsFour patient databases of patients with TBI treated in the ICU were used to validate three TBI specific models, two computerized tomography (CT) scoring systems, one trauma scoring system, and three intensive care scoring systems. Models were validated by assessing their discrimination using area under the curve (AUC), calibration, and explanatory variation. Logistic regression was used for model customization and development. Models were internally validated using a resample bootstrap technique or a split‐sample technique. Primary outcome was 6‐month mortality and unfavorable neurological outcome by the Glasgow Outcome Scale. 30‐day in‐hospital mortality was used for the trauma scoring system.ResultsStudy populations ranged from 342 to 9915 patients. The TBI models showed the best performance with AUCs between 0.80 and 0.85, followed by the intensive care scoring systems and the CT scores with AUCs between 0.68 to 0.80 and 0.63 to 0.70, respectively. Most models showed poor calibration, although good calibration was achieved following customization. The trauma scoring system exhibited modest to good discrimination (AUC 0.76–0.89) for short‐term mortality prediction but poor calibration. Several new prognostic models, with statistically significant superior performance to previous models were created, among them a combined TBI‐ICU model (‘IMPACT‐APACHE’) and a novel CT scoring system (‘The Helsinki CT score’). Using a TBI‐specific model, based on admission characteristics, up to 40% of the patient's final long‐term outcome could be predicted.ConclusionThe TBI models showed superior predictive performance to the intensive care and trauma scoring systems, showing that TBI patients are a highly specific population in the trauma and ICU setting. Thus, the use of a TBI‐specific model is advocated in the setting of TBI. The newly proposed models were found to be significant improvements over previous models, but require external validation to show generalizability.

Effect of vitamin e on the quality of frozen buck semen

A total of 40 ejaculates collected from five Beetal bucks twice weekly were used to study the effect of 0 (control), 2, 5 and 7 mM vitamin E on the quality of frozen semen by split sample technique. The semen extended using Tris was filled in French mini straws (0.25 ml) and sealed with polyvinyl alcohol powder of different colours for identification of semen of different bucks processed with different concentrations of vitamin E. The mean per cent, sperm motility, live sperm, live intact acrosome and hypo-osmotic sperm swelling test (HOST)-reacted sperm were significantly (P<0.05) higher in the extender with 2 mM vitamin E (63.75±0.56, 64.29±0.38, 45.24±0.42 and 52.89±0.23, respectively) than that with 5, 7 mM vitamin E and the control. The release of alanine transaminase and aspartate transaminase from post-thaw spermatozoa was also the lowest (35.67±0.31 and 215.08±0.41 U/L, respectively) in the extender containing 2 mM vitamin E.

Prognostic Benefit of the Addition of a Quantitative Index of Hepatic Encephalopathy to the MELD score: the MELD‐EEG

A slowed electroencephalogram (EEG) is indicative of the presence of hepatic encephalopathy (HE). Since HE is not reflected in the MELD score and is an important prognostic parameter, we assess the prognostic benefit of the addition of an EEG-based HE index to the MELD. Three hundred and ninety-two patients with cirrhosis underwent EEG and automated determination of its mean dominant frequency (MDF). MELD was calculated at the time of EEG recording. Patients were monitored for up to 18months in relation to the occurrence of death/transplantation. The prognostic value of the stand-alone/combined MELD and MDF was calculated using standard survival analysis techniques. Patients transplanted for hepatic decompensation were considered dead on the day of transplantation, those transplanted for hepatocellular carcinoma were censored. The findings were validated using a split-sample technique (reference group: n=256; test group: n=136). During the follow-up period, 107 patients died/were transplanted for hepatic decompensation. Both MELD and MDF predicted mortality on Kaplan-Meier analysis, and both were independent predictors of mortality on a Cox model. Based on Cox regression parameters, a novel prognostic index was devised, as follows: MELD-EEG=0.087*MELD-0.306*MDF. On ROC curve analysis, MELD-EEG had higher prognostic accuracy in predicting 12- and 18-month mortality compared to MELD (P=0.016 and P=0.018, respectively). In addition, it had better sensitivity and reduced the misclassification rate for given levels of specificity. On validation, no significant differences were observed between the reference/test groups. The addition of an automatically obtained EEG-based index improves the prognostic accuracy of the MELD score.

Institutional framework and capital structure of microfinance institutions

This article addresses the question of whether institutional frameworks matter in the capital structure of microfinance institutions. We studied a sample of 292 MFIs between 2004 and 2009. Our findings suggest that creditor rights, a country's legal tradition, and the level of financial sector development are significantly related to MFIs' level of external finance. Furthermore, the positive relationship between banking sector development and borrowings enables us to conclude that the microfinance sector and the formal banking sector are complementary. In addition, a split sample technique is used in order to assess the external validity of the model. Findings from this cross-validation strengthen the results obtained from the whole sample and indicate that our model seems to predict well the effect of institutional variables on the capital structure of MFIs.

Predicting six-month mortality of patients with traumatic brain injury: usefulness of common intensive care severity scores

IntroductionThe aim of this study was to evaluate the usefulness of the APACHE II (Acute Physiology and Chronic Health Evaluation II), SAPS II (Simplified Acute Physiology Score II) and SOFA (Sequential Organ Failure Assessment) scores compared to simpler models based on age and Glasgow Coma Scale (GCS) in predicting long-term outcome of patients with moderate-to-severe traumatic brain injury (TBI) treated in the intensive care unit (ICU).MethodsA national ICU database was screened for eligible TBI patients (age over 15 years, GCS 3–13) admitted in 2003–2012. Logistic regression was used for customization of APACHE II, SAPS II and SOFA score-based models for six-month mortality prediction. These models were compared to an adjusted SOFA-based model (including age) and a reference model (age and GCS). Internal validation was performed by a randomized split-sample technique. Prognostic performance was determined by assessing discrimination, calibration and precision.ResultsIn total, 1,625 patients were included. The overall six-month mortality was 33%. The APACHE II and SAPS II-based models showed good discrimination (area under the curve (AUC) 0.79, 95% confidence interval (CI) 0.75 to 0.82; and 0.80, 95% CI 0.77 to 0.83, respectively), calibration (P > 0.05) and precision (Brier score 0.166 to 0.167). The SOFA-based model showed poor discrimination (AUC 0.68, 95% CI 0.64 to 0.72) and precision (Brier score 0.201) but good calibration (P > 0.05). The AUC of the SOFA-based model was significantly improved after the insertion of age and GCS (∆AUC +0.11, P < 0.001). The performance of the reference model was comparable to the APACHE II and SAPS II in terms of discrimination (AUC 0.77; compared to APACHE II, ΔAUC −0.02, P = 0.425; compared to SAPS II, ΔAUC −0.03, P = 0.218), calibration (P > 0.05) and precision (Brier score 0.181).ConclusionsA simple prognostic model, based only on age and GCS, displayed a fairly good prognostic performance in predicting six-month mortality of ICU-treated patients with TBI. The use of the more complex scoring systems APACHE II, SAPS II and SOFA added little to the prognostic performance.

Multiple twinning in pure hexagonal close-packed titanium

Commercial pure titanium (T40) was deformed in channel die compression by means of the split-sample technique in order to study multiple twinning. Particular attention was paid to the twin variant presentation and selection during multiple twinning. All possible misorientations, corresponding to the multiple twins arising from the combination of the {1 1 {\overline 2} 2} compression (C) twin, the {1 0 {\overline 1} 2} tension twin (T1) and the {1 1 {\overline 2} 1} tension twin (T2), were calculated with respect to the crystal basis of the matrix grain. All the multiple twin variants are partitioned into ten classes with the same crystallographically equivalent misorientation angle and axis. However, when the influence of twinning order is taken into account, the multiple twin variants are partitioned into 15 classes. Experimental results prove that the selection of twin variants (primary and secondary) is mainly governed by their macroscopic Schmid factor (SF). The normalized SF is more efficient at predicting variant selection. A twin formed in one grain can activate another twin in a neighbouring grain, provided that the angle between the two twinning planes does not exceed 20°.

Self-Efficacy in Social Work: Development and Initial Validation of the Self-Efficacy Scale for Social Workers

Self-efficacy beliefs do not reflect a generic sense of competence, but are instead context-specific. Therefore, self-efficacy should be assessed by using an ad hoc scale measuring individual behaviors that allows social workers to exercise influence over events that affect their work life. The present study describes the development and initial validation of the self-efficacy scale for social workers (SESSW). Items were generated through the Critical Incident Technique. Sixteen social workers with at least 10 years of service participated in two focus groups; they were asked to recall critical incidents in their work and to indicate the most effective behaviors to manage the incidents. Content analysis of the focus group transcripts provided 13 key self-efficacy beliefs. The 13-item scale was validated with a sample of 805 social workers. Data were analyzed using a split-sample technique. Exploratory factor analysis on the first split sample (n = 402) revealed three dimensions of self-efficacy, corresponding to emotion regulation, support request, and procedural self-efficacy. The three-factor structure of the scale was further confirmed with confirmatory factor analysis on the second split sample (n = 403). Our results show that SESSW is an adequate instrument for assessment of self-efficacy beliefs in social work.

222 DIAGNOSTIC VALUE OF PRESEPSIN IN CIRRHOTIC PATIENTS

Background and Aims: A reduced EEG mean dominant frequency (MDF <7.3 Hz) is indicative of hepatic encephalopathy (HE). Since HE is not reflected in the MELD score and is an important prognostic parameter, the aim of this study was to assess the prognostic benefit of the addition of an EEG-based index to the MELD score. Methods: 392 consecutive patients with decompensated cirrhosis underwent an EEG with automated MDF determination. MELD was calculated at the time of EEG. Patients were excluded if they had advanced hepatocellular carcinoma, HE ≥ grade III or significant comorbidity. They were monitored for up to 18 months (median 12 months) in relation to the occurrence of death/lliver transplantation. The prognostic value of the stand-alone/combined MELD and MDF indices was calculated using standard survival analysis techniques (patients transplanted for hepatic decompensation were considered dead on the day of transplantation, those transplanted for hepatocellular carcinoma were censored). The findings were validated using a split sample technique: the Cox regression curve was re-calculated in a random sample of 259 patients, and the remaining 133 served as a test group. Results: During the follow-up period, 107 patients died/were transplanted for hepatic decompensation. Both the MELD and the MDF predicted mortality on Kaplan–Meier analysis, and both were independent predictors of mortality on a Cox model.

221 NEW CUTOFF VALUES FOR SARCOPENIA FOR PREDICTING 6-MONTH MORTALITY IN CIRRHOTIC PATIENTS

Background and Aims: A reduced EEG mean dominant frequency (MDF <7.3 Hz) is indicative of hepatic encephalopathy (HE). Since HE is not reflected in the MELD score and is an important prognostic parameter, the aim of this study was to assess the prognostic benefit of the addition of an EEG-based index to the MELD score. Methods: 392 consecutive patients with decompensated cirrhosis underwent an EEG with automated MDF determination. MELD was calculated at the time of EEG. Patients were excluded if they had advanced hepatocellular carcinoma, HE ≥ grade III or significant comorbidity. They were monitored for up to 18 months (median 12 months) in relation to the occurrence of death/lliver transplantation. The prognostic value of the stand-alone/combined MELD and MDF indices was calculated using standard survival analysis techniques (patients transplanted for hepatic decompensation were considered dead on the day of transplantation, those transplanted for hepatocellular carcinoma were censored). The findings were validated using a split sample technique: the Cox regression curve was re-calculated in a random sample of 259 patients, and the remaining 133 served as a test group. Results: During the follow-up period, 107 patients died/were transplanted for hepatic decompensation. Both the MELD and the MDF predicted mortality on Kaplan–Meier analysis, and both were independent predictors of mortality on a Cox model.

220 PROGNOSTIC BENEFIT OF THE ADDITION OF AN ELECTROENCEPHALOGRAPHIC (EEG) INDEX TO THE MELD SCORE: THE MELD-EEG

Background and Aims: A reduced EEG mean dominant frequency (MDF <7.3 Hz) is indicative of hepatic encephalopathy (HE). Since HE is not reflected in the MELD score and is an important prognostic parameter, the aim of this study was to assess the prognostic benefit of the addition of an EEG-based index to the MELD score. Methods: 392 consecutive patients with decompensated cirrhosis underwent an EEG with automated MDF determination. MELD was calculated at the time of EEG. Patients were excluded if they had advanced hepatocellular carcinoma, HE ≥ grade III or significant comorbidity. They were monitored for up to 18 months (median 12 months) in relation to the occurrence of death/lliver transplantation. The prognostic value of the stand-alone/combined MELD and MDF indices was calculated using standard survival analysis techniques (patients transplanted for hepatic decompensation were considered dead on the day of transplantation, those transplanted for hepatocellular carcinoma were censored). The findings were validated using a split sample technique: the Cox regression curve was re-calculated in a random sample of 259 patients, and the remaining 133 served as a test group. Results: During the follow-up period, 107 patients died/were transplanted for hepatic decompensation. Both the MELD and the MDF predicted mortality on Kaplan–Meier analysis, and both were independent predictors of mortality on a Cox model.

Attitudes Towards Migrant Workers in the GCC: Evidence from Qatar

With the majority of Qatar's total population made up of foreigners (high-skilled and low-skilled migrant workers), Qatari nationals may feel that there are significant challenges for their society; despite the absence of employment competition, this may lead many Qataris to see problems as well as benefits in the presence of these migrant workers in their country. Using a split-sample technique, Qataris' attitudes towards these foreigners were assessed. Results suggest that Qataris displayed a stronger positive attitude towards the high-skilled workers, but the difference was much smaller than that found in other societies. This may be attributed to Qataris' dependence on low-skilled migrants. However, even with the acknowledgement of Qatar's dependence on these workers, it is still a relatively rare phenomenon in the modern context.

Effect of diluters, breeds and storage period on boar semen characteristics

The study was conducted on 54 semen samples obtained from 9 boars comprising 3 each of Large White Yorkshire, Tamworth and T &amp; D (cross of Tamworth and Desi) by split sample technique to study the effect of different dilutors, genetic groups and hours of preservation on spermatozoa characteristics. The dilutors used were Kiev, Modena and lactose egg yolk (LEY). The sperm motility % was significantly highest in lactose egg yolk dilutor at all the hours of preservations. Irrespective of dilutors, the sperm motility% was significantly highest in T &amp; D boars. Live sperm count was significantly highest in lactose egg yolk dilutor than Kiev and Modena during the hours of preservation in all the boar breeds. The difference in head abnormality % was nonsignificant in all the breeds and dilutors at all the hours of preservation except at 96 h. Highly significant effect of both hours of preservation and dilutors on the incidence of tail abnormality was noted during the study. The % of tail abnormality revealed an increasing trend with increase in the duration of preservation. On dilutor wise comparison, it indicated lower incidence of tail abnormality with lactose egg yolk dilutor at all hours of preservation. Therefore, it may be concluded that LEY diluter can be successfully used for preservation of boar spermatozoa at 15°C in a BOD incubator up to 96 h.

Accuracy and Robustness of House Price Index Methods

We evaluate the statistical properties of five different house price index methods with the objective of identifying one that is most accurate and robust when estimated at frequent time intervals and for distinctly local markets. We adopt a split-sample technique to establish a consistent basis for comparison of the different price index methods. Our results demonstrate that if suitable data is available for estimation of price indexes, the arbitrary aggregation of data across time and geography is not warranted. One model, the ‘hedonic imputation’, outperforms alternative models on all measures of accuracy and robustness. Differences in levels of accuracy between different models are found to be statistically significant.

A longitudinal study of the effects of charismatic leadership and organizational culture on objective and perceived corporate performance

We investigated the combined effects of charismatic leadership and organizational culture on perceived and objective company performance using a longitudinal design. Employees (N=1214) in 46 branches of a large Dutch bank rated branch management on charismatic leadership, organizational culture in terms of work practices, as well as perceived organizational performance. Objective performance data were collected twice, two years apart. The split sample technique attenuated common source bias. Results of structural equation modeling, in which Time 1 financial performance measures were controlled, revealed that charisma increased financial performance; however culture did not do so. Culture and charisma were significantly related to perceived performance, and culture and charisma were interrelated. A longer time interval may be necessary before the effects of culture on financial performance become apparent. The findings are discussed against the backdrop of the value of intangible resources.

Composition and extraction of essential oil from Rumex chalepensis using hydrodistillation

The aim of our study was to evaluate the chemical composition of Rumex chalepensis essential oil. From the aerial parts of Rumex chalepensis at the flowering stage, a yellowish oil was obtained at a yield of 0.03% (w/w). Thirty-three components were identified, accounting for 66.3% of the total oil. p-Menth-2-en-ol (18.8%) was determined as the major constituent in the extract. The other major components in the oil of Rumex chalepensis were identified as dibutyl phthalate (6.5%), fleximel (4.3%), and dodecane (3.4%). It was also confirmed that the oxygenated and non-oxygenated terpenes made up 20.5% and 1.2% of the extract, respectively. The percentage composition of the various oil components is listed in Table 1. Plant Material. Arial parts of Rumex chalepensis were collected at the flowering stage from Southern Khorasan, Birjand, Iran, in June 2010, and identified at the Research Center for Plant Sciences, Ferdowsi University of Mashhad, Iran. A voucher specimen has been deposited in the Herbarium of Research Center for Plant Sciences. Isolation of the Essential Oil. Arial parts of Rumex chalepensis were air-dried for 5 days before isolation of essential oil. The plant material (100 g) was cut into small pieces and the essential oil obtained by hydrodistillation with a Clevenger-type apparatus until there was no significant increase in the volume of the oil collected (6 h). The yield of the yellow oil was 0.03% (w/w) based on the dry weight of the plant. GC and GC-MS Analysis. GC analysis of the oil from the aerial parts of the plant was performed using a Shimadzu GC-MS-QP (2010) gas chromatograph equipped with flame ionization detector (FID) and an RTx-5MS column (95% diphenyl– 5% dimethylpolysiloxane, 15 m 0.25 mm.i.d., film thickness 0.25 m). The oven temperature was programmed to 35–280C at a rate of 5C/min; the carrier gas was helium with a flow rate of 1 mL/min, and the sample was injected using the split sampling technique 1:10. The percentage composition of the oil was calculated automatically from peak areas without any correction. Retention indices (RI) were determined by comparing with the retention times of a series of n-alkanes with linear interpolation. Identification of each component was confirmed by comparison of its retention index either with those of authentic compounds or with data in the literature [8–10].