Impact of structure on unified efficiency for Chinese service sector—A two-stage analysis

2018 ◽  
Vol 231 ◽  
pp. 876-886 ◽  
Author(s):  
Guanglu Zhang ◽  
Boqiang Lin
1996 ◽  
Vol 84 (3) ◽  
pp. 526-532 ◽  
Author(s):  
I. Murat ◽  
V. Billard ◽  
J. Vernois ◽  
M. Zaouter ◽  
P. Marsol ◽  
...  

Background No complete pharmacokinetic profile of propofol is yet available in children younger than 3 yr, whereas clinical studies have demonstrated that both induction and maintenance doses of propofol are increased with respect to body weight in this age group compared to older children and adults. This study was therefore undertaken to determine the pharmacokinetics of propofol after administration of a single dose in aged children 1-3 yr requiring anesthesia for dressing change. Methods This study was performed in 12 children admitted to the burn unit and in whom burn surface area was less than or equal to 12% of total body surface area. Exclusion criteria were: unstable hemodynamic condition, inappropriate fluid loading, associated pulmonary injury, or burn injury older than 2 days. Propofol (4 mg.kg(-1))plus fentanyl (2.5 microg.kg(-1)) was administered while the children were bathed and the burn area cleaned during which the children breathed spontaneously a mixture of oxygen and nitrous oxide (50:50). Venous blood samples of 300 microl were obtained at 5, 15, 30, 60, 90, and 120 min, and 3, 4, 8, and 12 thereafter injection; an earlier sample was obtained from 8 of 12 children. The blood concentration curves obtained for individual children were analyzed by three different methods: noncompartmental analysis, mixed effects population model, and standard two-stage analysis. Results Using noncompartmental analysis, total clearance of propofol (+/-SD) was 0.053+/-0.013l.kg(-1).min(-1), volume of distribution at steady state9.5 +/- 3.7l.kg(-1),and residence time 188 +/- 85 min. Propofol pharmacokinetics were best described by a weight-proportional three-compartmental model in both population and two-stage analysis. Estimated and derived pharmacokinetic parameters were similar using these two pharmacokinetic approaches. Results of population versus two-stage analysis are as follow: systemic clearance 0.049 versus 0.048 l.kg(-).min(-1), volume of central compartment 1.03 versus 0.95 l.kg(-1), volume of steady state 8.09 versus 8.17 l.kg(-1). Conclusions The volume of the central compartment and the systemic clearance were both greater than all values reported in older children and adults. This is consistent with the increased propofol requirements for both induction and maintenance of anesthesia in children 1-3 yr. (Key words: Anesthesia: pediatric. Pharmacokinetics: propofol.)


2007 ◽  
Vol 1 (Suppl 1) ◽  
pp. S139 ◽  
Author(s):  
Tao Wang ◽  
Qing Lu ◽  
Monica Torres-Caban ◽  
Robert C Elston

2020 ◽  
Author(s):  
Anna-Carolina Haensch ◽  
Bernd Weiß

An increasing number of researchers pool, harmonize, and analyze survey data from different survey providers for their research questions. They aim to study heterogeneity between groups over a long period or examine smaller subgroups; research questions that can be impossible to answer with a single survey. This combination or pooling of data is known as individual person data (IPD) meta-analysis in medicine and psychology; in sociology, it is understood as part of ex-post survey harmonization (Granda et al 2010).However, in medicine or psychology, most original studies focus on treatment or intervention effect and apply experimental research designs to come to causal conclusions. In contrast, many sociological or economic studies are nonexperimental. In comparison to experimental data, survey-based data is subject to complex sampling and nonresponse. Ignoring the complex sampling design can lead to biased population inferences not only in population means and shares but also in regression coefficients, widely used in the social sciences (DuMouchel and Duncan 1983 and Solon et al. 2013). To account for complex sampling schemes or non-ignorable unit nonresponse, survey-based data often comes with survey weights. But how to use survey weights after pooling different surveys?We will build upon the work done by DuMouchel and Duncan (1983) and Solon et al. (2013) for survey-weighted regression analysis with a single data set. Through Monte Carlo (MC) simulations, we will show that endogenous sampling and heterogeneity of effects models require survey weighting to receive approximately unbiased estimates after ex-post survey harmonization. Second, we focus on a list of methodological questions: Do survey-weighted one-stage and two-stage (meta-)analytical approaches perform differently? Is it possible to include random effects, especially if we have to assume study heterogeneity? Another challenging methodological question is the inclusion of random effects in a one-stage analysis.Our simulations show that two-stage analysis will be biased if the weights' variation is high, whereas one-stage analysis remains unbiased. We also show that the inclusion of random effects in a one-stage analysis is challenging but doable, i.e., weights must be transformed in most cases. Apart from the MC simulations, we also show the difference between two-stage and one-stage approaches with real-world data from same-sex couples in Germany.


2021 ◽  
Vol 19 (1) ◽  
pp. 892-917
Author(s):  
Yessica Andrea Mercado ◽  
◽  
César Augusto Henao ◽  
Virginia I. González

<abstract> <p>Considering an uncertain demand, this study evaluates the potential benefits of using a multiskilled workforce through a k-chaining policy with $k \ge 2$. For the service sector and, particularly for the retail industry, we initially propose a deterministic mixed-integer linear programming model that determines how many employees should be multiskilled, in which and how many departments they should be trained, and how their weekly working hours will be assigned. Then, the deterministic model is reformulated using a two-stage stochastic optimization (TSSO) model to explicitly incorporate the uncertain personnel demand. The methodology is tested for a case study using real and simulated data derived from a Chilean retail store. We also compare the TSSO approach solutions with the myopic approaches' solutions (i.e., zero and total multiskilling). The case study is oriented to answer two key questions: how much multiskilling to add and how to add it. Results show that TSSO approach solutions always report maximum reliability for all levels of demand variability considered. It was also observed that, for high levels of demand variability, a k-chaining policy with $k \ge 2$ is more cost-effective than a 2-chaining policy. Finally, to evaluate the conservatism level in the solutions reported by the TSSO approach, two truncation types in the probability density function (pdf) associated with the personnel demand were considered. Results show that, if the pdf is only truncated at zero (more conservative truncation) the levels of required multiskilling are higher than when the pdf is truncated at 5th and 95th percentiles (less conservative truncation).</p> </abstract>


2019 ◽  
Vol 38 (16) ◽  
pp. 2956-2971
Author(s):  
Takanori Kawabata ◽  
Ryo Emoto ◽  
Jo Nishino ◽  
Kunihiko Takahashi ◽  
Shigeyuki Matsui

Diachronica ◽  
1991 ◽  
Vol 8 (2) ◽  
pp. 201-238 ◽  
Author(s):  
Robert W. Murray

SUMMARY This paper discusses four approaches to the reconstruction of the early Germanic syllabication of VCRV and VCRV sequences; A) Murray & Vennemann (1983) and Murray (1988), B) Barrack (1989), C) Dresher & Lahiri (1991), and D) Liberman (1990). Approach A develops a two-stage analysis involving Proto-Germanic VC$RV and V$CR$(R)V in accordance with Sievers' Law and subsequent reduction of V$CR$(R)V to VC$RV in the early dialects (with some dialect-specific variation). These syllabications provide the basis for a treatment of important phonological changes in early Germanic on the basis of a preference theory for syllable structure. Although VC$RV and VC$RV represent marked syllable structure in that poor syllable contacts result, motivation for this syllabication can be found in the Stressed Syllable Law and Streitberg's law of mora conservation. By contrast, the approaches outlined in B, C, and D run into major problems. It is shown in each of these cases that the problems can be directly traced to the alternative syllabications assumed and concluded that only approach A has succeeded in providing a comprehensive and coherent treatment of relevant aspects of early Germanic phonology. RÉSUMÉ Le présent article discute quatre façons de reconstruire la syllabation des séquences VCRV et VCRV en ancien germanique, à savoir A) Murray et Vennemann (1983) and Murray (1988), B) Barrack (1989), C) Dresher & Lahiri (1991), ainsi que D) Liberman (1990). L'approche A développe une analyse à deux étapes qui implique les structures proto-germaniques VC$RV et V$CR$(R)V selon la loi de Sievers, suivi de la réduction de V$CR$(R)V à VC$RV dans les anciens dialectes (avec quelques variations spécifiques à certains dialectes). Ces syllabations nous fournissent une base pour le traitement de changements phonologiques importants en ancien germanique, en termes d'une théorie de préférence pour les structures syllabiques. Bien que VC$RV soit une structure syllabique marquée (puisqu'elle produit des contacts syllabiques médiocres), la motivation de cette syllabation se retrouve dans la 'loi des syllabes accentuées' et dans la concept de la loi de conservation des 'moras' de Streitberg. Par contraste, les approches B, C, et D rencontrent de sérieux problèmes. L'article démontre que dans chaque de ces cas, les problèmes peuvent être retracés directement au type de syllabation utilisé, ce qui amène à conclure que seulement l'approche A réussit à fournir un traitement compréhensif et cohérent des aspects pertinents de la phonologie de l'ancien germanique. ZUSAMMENFASSUNG In diesem Aufsatz werden vier verschiedene Auffasungen zur möglichen Rekonstruktion der frühgermanischen Silbenstruktur in den VCRV- und VCRV-Abfolgen vorgestellt und miteinander verglichen: A) Murray & Vennemann (1983) und Murray (1988); B) Barrack (1989); C) Dresher & Lahiri (1991) und D) Liberman (1990). In A werden zwei Stufen angenom-men: Stufe 1 mit urgermanischen VC$RV und V$CR$(R)V nach dem Siever-schen Gesetz und Stufe 2 mit VC$RV nach Reduktion der dreisilbischen Struktur in den Dialekten. Dièse Syllabierungen liefern die Grundlage fur eine Analyse wichtiger phonologischer Veränderungen im Frühgermanischen im Lichte einer Präferenztheorie fur Silbenstruktur. Obwohl VC$RV und VC$RV markierte Silbenstrukturen darstellen (da sie ungünstige Silbenkontakte ent-halten), finden sie ihre Motivation in dem Silbenbetonungsgesetz und im Streit-bergschen Mora-Gesetz. Im Gegensatz hierzu weisen B, C und D groBe Erklä-rungsschwierigkeiten auf. In jedem einzelnen Fall wird der Nachweis erbracht, daB diEse Schwierigkeiten auf die alternative Rekonstruktion der urgermanischen Silbenstruktur (z.B. V$CRV) zunickzufuhren sind. Es wird gefolgert, daB nur die in A vorgeschlagene Analyse eine angemessene Grundlage für die Untersuchung der frühgermanischen Phonologie liefert.


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