bluuebunny/crossref_metadata_2025 huggingface dataset:
ДОСЛІДЖЕННЯ ЕНЗИМНОЇ ЛАНКИ АНТИОКСИДАНТНОЇ СИСТЕМИ В ЩУРІВ ЗА УМОВИ ДІЇ ТЮТЮНОВОГО ДИМУ НА ТЛІ ЗАСТОСУВАННЯ НАТРІЙ ГЛУТАМАТУ В СТАТЕВОМУ І ВІКОВОМУ АСПЕКТАХ
Authors: Rutska A. V.
Published: November 2018

Вступ. Значна розповсюдженість тютюнокуріння – глобальна проблема людства, на вирішення якої спрямовані зусилля багатьох учених і фахівців. Водночас відмітною особливістю сучасних харчових технологій є використання харчових добавок. До найпоширеніших харчових добавок як в Україні, так і в Європі належить натрій глутамат (Е621), який не завжди безпечний для здоров’я людини.

Мета дослідження – вивчити стан ензимної ланки антиоксидантної системи в щурів за умови дії тютюнового диму на тлі застосування натрій глутамату в статевому і віковому аспектах.

Методи дослідження. Досліди проведено на 96 білих нелінійних статевозрілих і статевонезрілих щурах обох статей. Кожну групу тварин було поділено на 4 підгрупи: 1-ша – контроль; 2-га – щури, яким моделювали “пасивне тютюнокуріння”; 3-тя – щури, яким вводили натрій глутамат; 4-та – щури, яким моделювали “пасивне тютюнокуріння” на тлі введення натрій глутамату.

Результати й обговорення. Надмірне утворення продуктів вільнорадикального окиснення за умови ізольованої дії тютюнового диму викликало виснаження антиоксидантного потенціалу крові та тканин легень, що проявлялося достовірним зменшенням супероксиддисмутазної активності в гемолізатах еритроцитів на 28,8 % відносно контрольної групи, а в супернатанті гомогенату легень – на 53,1 % (р<0,001) відповідно. “Пасивне тютюнокуріння” на тлі застосування натрій глутамату супроводжувалося більшим її зниженням (на 41,0 %, р<0,001) відносно контрольної групи, що на 17,1 % (р<0,02) менше від даного показника при ізольованій дії тютюнового диму в гемолізатах еритроцитів та на 58,7 % – у супернатанті гомогенату легень, що на 12,0 % (р<0,02) нижче від цього показника за умови ізольованої дії тютюнового диму. Однонаправлені зміни спостерігали і щодо каталазної активності.

Висновки. За умови дії тютюнового диму спостерігають виснаження антиоксидантного потенціалу (зниження супероксиддисмутазної і каталазної активності) крові та тканин легень, більш виражене при “пасивному тютюнокурінні” на тлі застосування натрій глутамату. В статевому аспекті показники антиоксидантного захисту за умови “пасивного тютюнокуріння” на тлі застосування натрій глутамату більш виражено знижуються в самок, а при віковому зіставленні змін активності даних ензимів встановлено їх інтенсивніше зменшення у статевонезрілих щурів.
Revision of the North American Genera Tetracis Guenée and Synonymization of Synaxis Hulst with Descriptions of Three New Species (Lepidoptera: Geometridae: Ennominae)
Authors: FERRIS CLIFFORD D. , SCHMIDT B.CHRISTIAN
Published: November 2018

The genus Synaxis is synonymized with Tetracis. The thirteen North American species in genus Tetracis (some formerly in Synaxis) are discussed, including descriptions of three new species from western North America: Tetracis australis, T. montanaria, T. pallidata. Two additional species, “Synaxis” triangulata and “S.” brunneilinearia are excluded. A key to species, descriptions, check list, illustrations of adults and genitalia, and distribution maps are included. The formerly presumed lost types of the taxa aurantiacaria, cervinaria, and jubararia were located and are illustrated.
Cardinalfish of the genus Apogonichthyoides Smith, 1949 (Apogonidae) with a description of a new species from the West-Pacific region
Authors: FRASER THOMAS H. , ALLEN GERALD R.
Published: November 2018

Apogonichthyoides is resurrected from Apogon (Ostorhinchus) as a valid genus with 19 species. Members of this genus are mostly tannish brown to brownish-black in body color. The head and body usually have brownish to blackish spots (sometimes stripe-like), a darkish cheek line and usually two body bars. An ocellus may be present below the lateral line on the body or absent. One or more caudal-peduncular bars and/or a basicaudal spot are often present. Insertion patterns of supraneurals and pterygiophores are given for 11 species. Apogonichthyoides umbratilis, a new species, has 14 pectoral rays and five bars (three faint) on the body and caudal peduncle. Color pattern of the new species suggest relationships with Apogonichthyoides gardineri, A. timorensis and A. opercularis. Descriptions and illustrations of the latter two species are provided for comparison. Apogonichthyoides gardineri, a rare, deep-water species is characterized by 14 pectoral rays, two bars on the body and one wide bar near the base of the caudal peduncle. Specimens of Apogonichthyoides timorensis usually have 15–16 pectoral rays and two or three bars on the body and caudal peduncle. Specimens of Apogonichthyoides opercularis have nine soft anal rays and 10 soft dorsal rays. A key to eight species included in the timorensis species group is provided. A lectotype and paralectotypes are designated for the syntype series of Apogon opercularis. New name combinations follow: Apogonichthyoides atripes, A. brevicaudatus, A. cantoris, A. chrysurus, A. euspilotus, A. gardineri, A. heptastygma, A. niger, A. opercularis, A. pharaonis, A. pseudotaeniatus, A. regani, A. sialis and A. timorensis. Previous usage includes: Apogonichthyoides enigmaticus, A. nigripinnis, A. taeniatus and A. uninotatus
The genus Microrchestia (Amphipoda: Talitridae) in eastern Australia
Authors: LOWRY J. K. , PEART R.
Published: November 2018

Microrchestia is reported from Australia for the first time and two new species are described, M. bousfieldi sp. nov. from northern New South Wales and M. watsonae sp. nov. from the northern Great Barrier Reef. The new genus Cochinorchestia is established for Microrchestia notabilis (K.H. Barnard), originally described from the Cochin area in south-eastern India.
Hydrologic Impacts of Ensemble-RCM-Projected Climate Changes in the Athabasca River Basin, Canada
Authors: Zhou Xiong , Huang Guohe , Piwowar Joseph , Fan Yurui , Wang Xiuquan , Li Zoe , Cheng Guanhui
Published: November 2018

In this study, the Providing Regional Climates for Impacts Studies (PRECIS) and the Regional Climate Model (RegCM) system as well as the Variable Infiltration Capacity (VIC) macroscale hydrologic model were integrated into a general framework to investigate impacts of future climates on the hydrologic regime of the Athabasca River basin. Regional climate models (RCMs) including PRECIS and RegCM were used to develop ensemble high-resolution climate projections for 1979–2099. RCMs were driven by the boundary conditions from the Hadley Centre Global Environment Model, version 2 with Earth system configurations (HadGEM2-ES); the Second Generation Canadian Earth System Model (CanESM2); and the Geophysical Fluid Dynamics Laboratory Earth System Model with MOM (GFDL-ESM2M) under the representative concentration pathways (RCPs). The ensemble climate simulations were validated through comparison with observations for 1984–2003. The RCMs project increases in temperature, precipitation, and wind speed under RCPs across most of the Athabasca River basin. Meanwhile, VIC was calibrated using the University of Arizona Shuffled Complex Evolution method (SCE-UA). The performance of the VIC model in replicating the characteristics of the observed streamflow was validated for 1994–2003. Changes in runoff and streamflow under RCPs were then simulated by the validated VIC model. The validation results demonstrate that the ensemble-RCM-driven VIC model can effectively reproduce historical climatological and hydrological patterns in the Athabasca River basin. The ensemble-RCM-driven VIC model shows that monthly streamflow is projected to increase in the 2050s and 2080s under RCPs, with notably higher flows expected in the spring for the 2080s. This will have substantial impacts on water balance on the Athabasca River basin, thus affecting the surrounding industry and ecosystems. The developed framework can be applied to other regions for exploration of hydrologic impacts under climate change.
Comparative Investigation of Secondary Cell Wall Development in Cotton Fiber Near Isogenic Lines Using Attenuated Total Reflection Fourier Transform Infrared Spectroscopy (ATR FT-IR)
Authors: Liu Yongliang , Kim Hee-Jin
Published: November 2018

In this investigation, we applied previously proposed simple algorithms to analyze the attenuated total reflection Fourier transform infrared (ATR FT-IR) spectra of cotton fibers during secondary cell wall (SCW) biosynthesis. The infrared crystallinity ( CIIR) and maturity ( MIR) indices were compared from developmental fibers representing two pairs of upland cotton near isogenic lines (NILs). One pair of NILs consisted of Texas Marker-1 (TM-1) and an immature fiber ( im) mutant that differ in fiber maturity. The other pair of NILs included MD52ne and MD90ne that show variations in fiber strength. The observations revealed significant difference in the MIR values between developmental TM-1 and im NILs grown at a field in crop year 2015, and also a significant difference in the CIIR values between these NILs grown at the same field in crop year 2011. These different patterns of CIIR and MIR values during fiber development for the two different crop years indicated the impact of genetics and crop year on the development of fiber maturity and crystallinity of the TM-1 and im fibers. Furthermore, the tendency of linking CIIR with MIR values suggested that the im fibers have more CIIR development than the TM-1 fibers when the fibers have the similar MIR values. In contrast, the NIL pair having variations in fiber strength showed insignificant differences in the patterns of CIIR and MIR as well as the relationship between CIIR and MIR values. The results suggested that CIIR and MIR indices from ATR FT-IR measurement could be used to facilitate the understanding of how fiber genetics and crop year affect fiber maturity and crystallinity during SCW biosynthesis.
What does the general national pride item measure? Insights from web probing
Authors: Meitinger Katharina
Published: November 2018

The general national pride question is a popular item in cross-national studies of national identity. Although it is a single-item indicator, researchers use it as a proxy for different aspects of national identity, such as national belonging, different forms of patriotism, and nationalism. This article evaluates the suitability of this item as a cross-national indicator for these aspects of national identity. It assesses which aspects of national identity respondents have in mind when providing a response to this item, whether these associations differ across countries, and how well the item works as a measure for the different aspects of national identity. By means of web probing results from a web survey conducted in five countries (Germany, Great Britain, Mexico, Spain, and the United States), we reveal that the general national pride is not a suitable proxy single-item indicator for specific aspects of national identity in a cross-national context because respondents associate different aspects of national identity with this item (issue of validity) and these associations differ across countries (issue of comparability). In addition, we uncovered several problem types that distorted the answer selection of respondents (issue of reliability). The vagueness of this item and the associated issues make the general national pride item a rather problematic cross-national indicator for specific elements of national identity. In addition, this study illustrates the potential of web probing for evaluating the measurement quality of single-item indicators.
Implementing a Data to Care Strategy to Improve Health Outcomes for People With HIV: A Report From the Care and Prevention in the United States Demonstration Project
Authors: Sweeney Patricia , Hoyte Tamika , Mulatu Mesfin S. , Bickham Jacquelyn , Brantley Antoine D. , Hicks Curt , McGoy Shanell L. , Morrison Melissa , Rhodes Anne , Yerkes Lauren , Burgess Samuel , Fridge Jessica , Wendell Deborah
Published: November 2018

Objectives:

The Care and Prevention in the United States Demonstration Project included implementation of a Data to Care strategy using surveillance and other data to (1) identify people with HIV infection in need of HIV medical care or other services and (2) facilitate linkages to those services to improve health outcomes. We present the experiences of 4 state health departments: Illinois, Louisiana, Tennessee, and Virginia.

Methods:

The 4 state health departments used multiple databases to generate listings of people with diagnosed HIV infection (PWH) who were presumed not to be in HIV medical care or who had difficulty maintaining viral suppression from October 1, 2013, through September 29, 2016. Each health department prioritized the listings (eg, by length of time not in care, by viral load), reviewed them for accuracy, and then disseminated the listings to staff members to link PWH to HIV care and services.

Results:

Of 16 391 PWH presumed not to be in HIV medical care, 9852 (60.1%) were selected for follow-up; of those, 4164 (42.3%) were contacted, and of those, 1479 (35.5%) were confirmed to be not in care. Of 794 (53.7%) PWH who accepted services, 694 (87.4%) were linked to HIV medical care. The Louisiana Department of Health also identified 1559 PWH as not virally suppressed, 764 (49.0%) of whom were eligible for follow-up. Of the 764 PWH who were eligible for follow-up, 434 (56.8%) were contacted, of whom 269 (62.0%) had treatment adherence issues. Of 153 PWH who received treatment adherence services, 104 (68.0%) showed substantial improvement in viral suppression.

Conclusions:

The 4 health departments established procedures for using surveillance and other data to improve linkage to HIV medical care and health outcomes for PWH. To be effective, health departments had to enhance coordination among surveillance, care programs, and providers; develop mechanisms to share data; and address limitations in data systems and data quality.
Factors Associated with Revision Surgery after Balloon Sinuplasty
Authors: Cooper Matthew , Cheng Tracy , Truong Tracy , Kuchibhatla Maragatha , Hachem Ralph Abi , Jang David W.
Published: November 2018

Objective

Although balloon sinuplasty (BSP) is increasing in popularity, little is known about which patients are the ideal candidates. The objective of this study is to investigate factors that may be associated with BSP failure.

Study Design

Retrospective review.

Setting

Academic center.

Subjects and Methods

This is a 6‐year (July 2011‐June 2017) retrospective review of patients who underwent BSP or revision endoscopic sinus surgery (rESS) after BSP within a single tertiary health system. Demographics, clinical findings, and radiographic findings were investigated for association with rESS via univariate analyses and a multivariable backward elimination selection procedure.

Results

A total of 154 patients were identified (median age, 53 years): 146 patients underwent BSP at a single health system, with 16 (11%) undergoing rESS; 8 patients underwent BSP at an outside institution and underwent rESS with the senior author. Mean ± SD follow‐up was 12.8 ± 16.6 months. Univariate analyses revealed that prior endoscopic sinus surgery, polyps, allergic rhinitis, and gram‐negative infection were significantly associated with rESS. As for radiographic findings, a higher Lund‐Mackay score, neo‐osteogenesis, moderate or complete opacification, and hyperdensities were associated with rESS. The final model after multivariable selection showed that higher radiographic scores (odds ratio, 1.08; 95% CI, 1.01‐1.17) and neo‐osteogenesis (odds ratio, 5.25; 95% CI, 1.68‐16.42) were associated with higher odds for rESS.

Conclusions

This study identifies several clinical and radiographic factors that may be associated with the need for rESS after BSP. Surgeons can take these factors into consideration when deciding whether a patient should forego BSP and undergo conventional FESS.
Treatment of isolated talonavicular coalition: Case report and literature review
Authors: Duan Xiaojun , Yang Liu
Published: November 2018

Tarsal coalition refers to an abnormal fibrous, cartilaginous, or bony connection that develops between two or more tarsal bones. Talocalcaneal coalition and calcaneonavicular coalition account for more than 90% of all cases of tarsal coalition. Coalition exists early at birth, but bony connection usually develops during the patient’s late growth period. Isolated cases of talonavicular coalition have rarely been reported. We herein report a case involving an 11-year-old patient with an isolated talonavicular coalition from a soft tissue to bony connection who was treated with arthroscopy for ankle arthritis. To our knowledge, this is the first case in which the whole formation of the talonavicular coalition was observed with a series of radiographic and magnetic resonance imaging examinations. The pain caused by the talonavicular coalition was managed by nonoperative treatment, while the ankle pain caused by the arthritis was relieved after ankle arthroscopy. At 6 years postoperatively, the patient remained pain-free while walking for 30 minutes and was satisfied with the operative outcome. Continuous follow-up confirmed that after the formation of talonavicular coalition, the coalition can continue to progress, forming bony talocalcaneal coalition and calcaneocuboid coalition.
Effects of coenzyme Q10 supplementation on oxidative stress and antioxidant enzyme activity in glazers with occupational cadmium exposure: A randomized, double-blind, placebo-controlled crossover clinical trial
Authors: Hormozi Maryam , Mirzaei Ramazan , Nakhaee Alireza , payandeh Abolfazl , Izadi Shahrokh , Haghighi Javid Dehghan
Published: November 2018

Recently, there is a growing interest for the use of antioxidants as a preventive agent against cadmium (Cd) intoxication. The current study aimed to investigate the effects of dietary coenzyme Q10 supplementation on oxidative stress and antioxidant enzymes activity in Cd-exposed glazers. In a randomized, double-blind, placebo-controlled 2-month crossover clinical trial, coenzyme Q10 (60 mg twice daily) or placebo was administrated to 40 male glazers occupationally exposed to Cd. The subjects were randomly assigned to the placebo and coenzyme Q10 groups ( n = 20 in each group). Total antioxidant capacity (TAC), superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase (CAT) as well as malondialdehyde (MDA) in the serum of glazers were measured at baseline and at the end of both intervention phases. The primary outcomes were the changes in serum levels of MDA, TAC and the activities of SOD, CAT, and GPx during administration with coenzyme Q10 versus placebo. Compared with placebo, treatment to coenzyme Q10 was associated with a significant reduction in serum MDA levels ( p < 0.001) While, there was no significant effect on the serum TAC levels ( p = 0.096). Also, the activity antioxidant enzymes of SOD ( p < 0.001) and GPx ( p = 0.003) were significantly higher and the CAT activity ( p < 0.001) was lower after 2-month coenzyme Q10 administration compared with placebo. Data demonstrated that coenzyme Q10 supplementation at a dose of 60 mg (twice daily) is effective in reducing oxidative stress marker level (MDA) and improving antioxidant enzymes activity in glazers exposed to Cd. However, further research is needed to assess coenzyme Q10 as a possible dietary intervention in Cd-exposed workers.

Trial Registration:

Iranian Registry of Clinical Trials Registration Number: IRCT2016061228407N1 ( www.who.int/ictrp/network/irct/en/ ).
Elevational transects of modern pollen samples: Site-specific temperatures as a tool for palaeoclimate reconstructions in the Alps
Authors: Furlanetto Giulia , Ravazzi Cesare , Badino Federica , Brunetti Michele , Champvillair Elena , Maggi Valter
Published: November 2018

The potential of quantitatively reconstructing climate from modern pollen assemblages from high mountain environments has been widely debated but seldom tested. We analysed the pollen deposition in 53 surface samples (mosses) in relation to July temperature in two elevational transects in the European Alps. Each surface-sample site was assigned climate data derived from the local-scale climate. We compared our results with a larger calibration set extracted from the European Modern Pollen Database (EMPD) and centred on the European Alps. This also was assigned local climate data. The main calibration set (234 pollen samples) had Alnus harmonized at genus level; in contrast, a second set was selected (174) that retained the taxonomic resolution of Alnus viridis, which is one of the main climate indicators in the timberline ecotone. The overall and individual pollen responses to July temperature were inferred by canonical correspondence analysis (CCA), generalized linear regression (eHOF) and weighted averaging (WA). Quantitative climate reconstructions for each sample site of the two elevational transects were obtained using transfer functions, that is, WA and WA partial least squares (WA-PLS) regressions. In each calibration set, around 30% of the pollen taxa show a relationship with July temperature through monotonic or unimodal functions. The best transfer function obtained has a good statistical performance, with a determination coefficient ( r2) of 0.74. We propose new calibration procedures formulated to include the full climate space of the modelled taxa, as well as to account for uphill pollen transport in the high mountains and for human activity.
Pocket-sized ultrasound device for internal jugular puncture: A randomized study of performance on a simulation model
Authors: Chetioui Adrien , Masia Thibaud , Claret Pierre-Géraud , Markarian Thibaut , Muller Laurent , Lefrant Jean Yves , de La Coussaye Jean Emmanuel , Roger Claire , Bobbia Xavier
Published: November 2018

Introduction:

The aims of our study were to compare the performance of experienced emergency physicians for internal jugular vein puncture using a conventional ultrasound device versus a pocket-sized ultrasound in a training model.

Methods:

In this single-center, prospective, randomized study, emergency physicians performed one puncture with each device in a randomized order. No emergency physicians used a pocket-sized ultrasound for central vascular catheter insertion in clinical practice. A medium-fidelity training model was used. Each image was judged based on an image quality scale from 0 to 5.

Results:

Twenty emergency physicians were included: nine females (45%), median experience 2.5 years [2.0;4.3]. The median time to achieve a puncture with the conventional ultrasound device was 22 s [17;26] versus 28 s [13;43] with the pocket-sized ultrasound ( p = 0.43). Eighteen (90%) emergency physician punctures were successful with the conventional ultrasound device versus 18 (90%) with the pocket-sized ultrasound ( p = 1). The image quality was 4 [3;5] in the conventional ultrasound device group versus 4 [3;5] in the pocket-sized ultrasound group ( p = 0.32).

Conclusion:

Pocket-sized ultrasound and conventional ultrasound device performances are not statistically different for internal jugular vein-guided ultrasonography in a training model. These results must be confirmed in a clinical study.
Oil change interval evaluation of civilian cars in urban traffic condition
Authors: Wei Lei , Duan Haitao , Jin Yongliang , Jia Dan , Chen Song , Liu Jianfang , Li Jian
Published: November 2018

In this study, it is tried to establish a theoretical model based on oil oxidation stability to evaluate the motor oil life. Five civilian cars and five motor oils were taken to eight road tests. The road tests contained two experiments taken in two test cars with the same car model, synthetic motor oil and test time, and three experiments taken in one test car with the same mineral oil to study the reliability and repeatability of the proposed method. The change characteristics of oxidation onset temperature, total acid number, and kinematic viscosity of test oils were analyzed. A theoretical model was established with the oxidation onset temperature and column chromatography method. The results showed the established theoretical model has the potential to quantitatively determine the remaining service time and operation mileage of the test oils with high accuracy and reliability. The test synthetic oils are able to operate approximately 11,000–13,000 km in 534–686 days in the typical urban traffic condition of China. The test mineral oils are capable of operating approximately 8200 km with 40 km/day or capable of operating 5723 km in 410 days. The proposed approach can provide some reference for end-users to drain their motor oil reasonably.
On an excursion through EC1: multimodality, ethnography and urban walking
Authors: Lamb James , Gallagher Michael Sean , Knox Jeremy
Published: November 2018

In this article we describe and critique a methodological exercise that brings together multimodality, ethnography and walking in order to investigate the city. Drawing on the experience of enacting our methodology in central London, we describe how an openness to the full range of meaning-making phenomena encountered during an unscripted excursion through the city provided ways of thinking critically about our relationship with the city. This research is undertaken against a backdrop of a growing critical interest in the complex and shifting nature of the urban environment, reflected in the range of approaches that investigate how we understand and experience our surroundings. Central to this methodological approach is the intersection of ethnography and multimodality which, when brought together within the device of an unscripted walk, provides valuable opportunities for thinking critically about our surroundings.
Haplotype Analysis in Population-based Association Studies
Authors: Mander A. P.
Published: November 2018

This paper describes how to use the command hapipf and introduces the command profhap written for Stata that analyzes population-based genetic data. For these studies, association can be linkage disequilibrium within a set of loci or al-lelic/haplotype association with disease status. Confidence intervals for odds ratios are calculated with or without adjustment for possible factors that are confounding the relationship. Additionally, this command allows the specification of many models of association that are not widely implemented.
From the Help Desk
Authors: McDowell Allen
Published: November 2018

Welcome to From the help desk. From the help desk is written by the people in Technical Services at StataCorp and deals with issues that they have found to be of concern to a large fraction of Stata users. It is the rare column in this series that deals with sophisticated programming issues because such issues, by definition, are not of concern to a large fraction of Stata users. From the help desk discusses the use of sophisticated programs and the use of sophisticated statistics.
Standardizing Anthropometric Measures in Children and Adolescents with New Functions for Egen
Authors: Vidmar Suzanna , Carlin John , Hesketh Kylie , Cole Tim
Published: November 2018

A new function for egen has been developed to allow transformation of child anthropometric data to z-scores using the LMS method and the reference data available from the 1990 British Growth Reference and the 2000 US CDC Growth Reference. An additional function allows for children to be categorized according to body mass index (weight/height2) using international cutoff points recommended by the Childhood Obesity Working Group of the International Obesity Taskforce.
Parameters behind “Nonparametric” Statistics: Kendall's tau, Somers’ D and Median Differences
Authors: Newson Roger
Published: November 2018

So-called “nonparametric” statistical methods are often in fact based on population parameters, which can be estimated (with confidence limits) using the corresponding sample statistics. This article reviews the uses of three such parameters, namely Kendall's τa, Somers’ D and the Hodges–Lehmann median difference. Confidence intervals for these are demonstrated using the somersd package. It is argued that confidence limits for these parameters, and their differences, are more informative than the traditional practice of reporting only p-values. These three parameters are also important in defining other tests and parameters, such as the Wilcoxon test, the area under the receiver operating characteristic (ROC) curve, Harrell's C, and the Theil median slope.
Analysis of Quantitative Traits using Regression and Log-linear Modeling when Phase is unknown
Authors: Mander A. P.
Published: November 2018

This function models the relationship between quantitative trait and the genotype of a person. It introduces a new syntax for model specification, which is necessary because when phase is unknown, the explanatory variables for the linear regression are never observed. The data must be a population-based sample because within family effects are not modeled.
A Note on the Concordance Correlation Coefficient
Authors: Steichen Thomas J. , Cox Nicholas J.
Published: November 2018

Program concord implements L. I. Lin's concordance correlation coefficient (Lin, 1989), as well as the limits-of-agreement procedure (Bland and Altman, 1986). Recently, Lin (2000) issued an erratum reporting a number of typographical errors in his seminal 1989 paper. Further, changes in Stata Version 7 required modification of concord. This note reports the effect of the errors and provides a corrected and updated program.
Structural Choice Analysis with Nested Logit Models
Authors: Heiss Florian
Published: November 2018

The nested logit model has become an important tool for the empirical analysis of discrete outcomes. There is some confusion about its specification of the outcome probabilities. Two major variants show up in the literature. This paper compares both and finds that one of them (called random utility maximization nested logit, RUMNL) is preferable in most situations. Since the command nlogit of Stata 7.0 implements the other variant (called non-normalized nested logit, NNNL), an implementation of RUMNL called nlogitrum is introduced. Numerous examples support and illustrate the differences between both specifications.
Comparative Assessment of Three Common Algorithms for Estimating the Variance of the Area under the Nonparametric Receiver Operating Characteristic Curve
Authors: Cleves Mario A.
Published: November 2018

The area under the receiver operating characteristic (ROC) curve is often used to summarize and compare the discriminatory accuracy of a diagnostic test or modality, and to evaluate the predictive power of statistical models for binary outcomes. Parametric maximum likelihood methods for fitting of the ROC curve provide direct estimates of the area under the ROC curve and its variance. Nonparametric methods, on the other hand, provide estimates of the area under the ROC curve, but do not directly estimate its variance. Three algorithms for computing the variance for the area under the nonparametric ROC curve are commonly used, although ambiguity exists about their behavior under diverse study conditions. Using simulated data, we found similar asymptotic performance between these algorithms when the diagnostic test produces results on a continuous scale, but found notable differences in small samples, and when the diagnostic test yields results on a discrete diagnostic scale.
Choosing an Appropriate Real-Life Measure of Effect Size: The Case of a Continuous Predictor and a Binary Outcome
Authors: Conroy Ronán M.
Published: November 2018

A case study of data on age and pregnancy is used to point up some morals for practicing data analysts, including the superiority of regression over t tests, exploratory scatterplot smoothing as a key method of checking form of relationship, and the value of logistic regression followed by adjust as a way of getting at the numbers of most interest.
Using Aalen's Linear Hazards Model to Investigate Time-varying Effects in the Proportional Hazards Regression Model
Authors: Hosmer David W. , Royston Patrick
Published: November 2018

In this paper, we describe a new Stata command, stlh, which estimates and tests for the significance of the time-varying regression coefficients in Aalen's linear hazards model; see Aalen (1989). We see two potential uses for this command. One may use it as an alternative to a proportional hazards or other nonlinear hazards regression model analysis to describe the effects of covariates on survival time. A second application is to use the command to supplement a proportional hazards regression model analysis to assist in detecting and then describing the nature of time-varying effects of covariates through plots of the estimated cumulative regression coefficients, with confidence bands, from Aalen's model. We illustrate the use of the command to perform this supplementary analysis with data from a study of residential treatment programs of different durations that are designed to prevent return to drug use.
From the Help Desk: Demand System Estimation
Authors: Poi Brian P.
Published: November 2018

This article provides an example illustrating how to use Stata to estimate systems of household demand equations. More generally, the techniques developed here can be used to estimate any system of nonlinear equations using Stata's maximum likelihood routines.
Implementing Tests with Correct Size in the Simultaneous Equations Model
Authors: Moreira Marcelo J. , Poi Brian P.
Published: November 2018

In this paper, we propose a fix to the size distortions of tests for structural parameters in the simultaneous equations model by computing critical value functions based on the conditional distribution of test statistics. The conditional tests can then be used to construct informative confidence regions for the structural parameter with correct coverage probability. Commands to implement these tests in Stata are also introduced.
Multiple—test Procedures and Smile Plots
Authors: Newson Roger ,   The ALSPAC Study Team
Published: November 2018

multproc carries out multiple-test procedures, taking as input a list of p-values and an uncorrected critical p-value, and calculating a corrected overall critical p-value for rejection of null hypotheses. These procedures define a confidence region for a set-valued parameter, namely the set of null hypotheses that are true. They aim to control either the family-wise error rate (FWER) or the false discovery rate (FDR) at a level no greater than the uncorrected critical p-value. smileplot calls multproc and then creates a smile plot, with data points corresponding to estimated parameters, the p-values (on a reverse log scale) on the y-axis, and the parameter estimates (or another variable) on the x-axis. There are y-axis reference lines at the uncorrected and corrected overall critical p-values. The reference line for the corrected overall critical p-value, known as the parapet line, is an informal “upper confidence limit” for the set of null hypotheses that are true and defines a boundary between data mining and data dredging. A smile plot summarizes a set of multiple analyses just as a Cochrane forest plot summarizes a meta-analysis.
CDSIMEQ: A Program to Implement Two-stage Probit Least Squares
Authors: Keshk Omar M. G.
Published: November 2018

The cdsimeq command implements the two-stage probit least squares estimation method described in Maddala (1983) for simultaneous equations models in which one of the endogenous variables is continuous and the other endogenous variable is dichotomous.1 The cdsimeq command implements all the necessary procedures for obtaining consistent estimates for the coefficients, as well as their corrected standard errors.
Production Function Estimation in Stata using Inputs to Control for Unobservables
Authors: Petrin Amil , Poi Brian P. , Levinsohn James
Published: November 2018

A key issue in the estimation of production functions is the correlation between unobservable productivity shocks and input levels. Profit-maximizing firms respond to positive productivity shocks by expanding output, which requires additional inputs. Negative shocks lead firms to pare back output, decreasing their input usage. Olley and Pakes (1996) develop an estimator that uses investment as a proxy for these unobservable shocks. More recently, Levinsohn and Petrin (2003a) introduce an estimator that uses intermediate inputs as proxies, arguing that intermediates may respond more smoothly to productivity shocks. This paper reviews Levinsohn and Petrin's approach and introduces a Stata command that implements it.
Confidence Intervals for Kernel Density Estimation
Authors: Fiorio Carlo V.
Published: November 2018

This article describes asciker and bsciker, two programs that enrich the possibility for density analysis using Stata. asciker and bsciker compute asymptotic and bootstrap confidence intervals for kernel density estimation, respectively, based on the theory of kernel density confidence intervals estimation developed in Hall (1992b)and Horowitz (2001). asciker and bsciker allow several options and are compatible with Stata 7 and Stata 8, using the appropriate graphics engine under both versions.
Graphing Confidence Ellipses: An Update of Ellip for Stata 8
Authors: Alexandersson Anders
Published: November 2018

This paper describes an update of the ellip command for graphing confidence ellipses in Stata 8. Two of the most notable new features are the option to graph confidence ellipses around variable means and the ability to add inscribed lines. These features allow a geometric characterization of linear regression with unequal error variances, as in McCartin (2003).
Understanding the Multinomial-Poisson Transformation
Authors: Guimarães Paulo
Published: November 2018

There is a known connection between the multinomial and the Poisson likelihoods. This, in turn, means that a Poisson regression may be transformed into a logit model and vice versa. In this paper, I show the data transformations required to implement this transformation. Several examples are used as illustrations.
Speaking Stata: Graphing Agreement and Disagreement
Authors: Cox Nicholas J.
Published: November 2018

Many statistical problems involve comparison and, in particular, the assessment of agreement or disagreement between data measured on identical scales. Some commonly used plots are often ineffective in assessing the fine structure of such data, especially scatterplots of highly correlated variables and plots of values measured “before” and “after” using tilted line segments. Valuable alternatives are available using horizontal reference patterns, changes plotted as parallel lines, and parallel coordinates plots. The quantities of interest (usually differences on some scale) should be shown as directly as possible, and the responses of given individuals should be identified as easily as possible.
Confidence Intervals for the Kappa Statistic
Authors: Reichenheim Michael E.
Published: November 2018

The command kapci calculates 100(1 –α)% confidence intervals for the kappa statistic using an analytical method in the case of dichotomous variables or bootstrap for more complex situations. For instance, kapci allows estimating CI for polychotomous variables using weighted kappa or for cases in which there are more than 2 raters/replications.
Boolean Logit and Probit in Stata
Authors: Braumoeller Bear F.
Published: November 2018

This paper introduces new statistical models, Boolean logit and probit, that allow researchers to model binary outcomes as the results of Boolean interactions among independent causal processes. Each process (or “causal path”) is modeled as the unobserved outcome in a standard logit or probit equation, and the dependent variable is modeled as the observed product of their Boolean interaction. Up to five causal paths can be modeled, in any combination-A and B and C produce Y, A and (B or [C and D]) produce Y, etc.
Review of a Visual Guide to Stata Graphics by Mitchell
Authors: Kohler Ulrich
Published: November 2018

The new book by Mitchell (2004) is reviewed.
Visualizing Main Effects and Interactions for Binary Logit Models
Authors: Mitchell Michael N. , Chen Xiao
Published: November 2018

This paper considers the role of covariates when using predicted probabilities to interpret main effects and interactions in logit models. While predicted probabilities are very intuitive for interpreting main effects and interactions, the pattern of results depends on the contribution of covariates. We introduce a concept called the covariate contribution, which reflects the aggregate contribution of all of the remaining predictors (covariates) in the model and a family of tools to help visualize the relationship between predictors and the predicted probabilities across a variety of covariate contributions. We believe this strategy and the accompanying tools can help researchers who wish to use predicted probabilities as an interpretive framework for logit models acquire and present a more comprehensive interpretation of their results. These visualization tools could be extended to other models (such as binary probit, multinomial logistic, ordinal logistic models, and other nonlinear models).
A Menu-driven Facility for Complex Sample Size Calculation in Randomized Controlled Trials with a Survival or a Binary Outcome: Update
Authors: Barthel Friederike M.-S. , Royston Patrick , Babiker Abdel
Published: November 2018

Royston and Babiker (2002) presented a menu-driven Stata program for the calculation of sample size or power for complex clinical trial designs under a survival time or binary outcome. In the present article, the package is updated to Stata 8 under the new name ART. Furthermore, the program has been extended to incorporate noninferiority designs and provides more detailed output. This package is the only realistic sample size tool for survival studies available in Stata.
Exploratory Analysis of Single Nucleotide Polymorphism (SNP) for Quantitative Traits
Authors: Cleves Mario A.
Published: November 2018

With the decreasing cost and the increasing ability to quickly genotype single nucleotide polymorphisms (SNP) across the human genome, large databases containing possibly hundreds of typed SNPs are becoming common in population-based studies of quantitative traits. Testing for association between individual SNPs and the quantitative trait is an important first step in the discovery of disease susceptibility SNPs. This task, however, could be time-consuming and tedious if a large number of SNPs is involved. In this article, I introduce two new commands designed to facilitate the screening and testing of multiple SNPs for possible association with quantitative traits.
Estimation and Testing of Fixed-effect Panel-data Systems
Authors: Blackwell J. Lloyd
Published: November 2018

This paper describes how to specify, estimate, and test multiple-equation, fixed-effect, panel-data equations in Stata. By specifying the system of equations as seemingly unrelated regressions, Stata panel-data procedures worked seamlessly for estimation and testing of individual variable coefficients, but additional routines using test were needed for testing of individual equations and differences between equations.
Review of Regression Methods in Biostatistics: Linear, Logistic, Survival, and Repeated Measures Models by Vittinghoff, Glidden, Shiboski, and McCulloch
Authors: Lemeshow Stanley , Moeschberger Melvin L.
Published: November 2018

The new book by Vittinghoff et al. (2005) is reviewed.
Introduction to Game-theory Calculations
Authors: Orsini Nicola , Rizzuto Debora , Nante Nicola
Published: November 2018

Game theory can be defined as the study of mathematical models of conflict and cooperation between intelligent and rational decision makers (Myerson 1991). Game-theory concepts apply in economy, sociology, biology, and health care, and whenever the actions of several agents (individuals, groups, or any combination of these) are interdependent. We present a new command gamet to represent the extensive form (game tree) and the strategic form (payoff matrix) of a noncooperative game and to identify the solution of a nonzero and zero-sum game through dominant and dominated strategies, iterated elimination of dominated strategies, and Nash equilibrium in pure and fully mixed strategies. Further, gamet can identify the solution of a zero-sum game through maximin criterion and the solution of an extensive form game through backward induction.
Decomposing Inequality and Obtaining Marginal Effects
Authors: López-Feldman Alejandro
Published: November 2018

This article describes a user-written command, descogini, that decomposes the Gini coefficient by income source and allows the calculation of the impact that a marginal change in a particular income source will have on inequality. descogini can be used with bootstrap to obtain standard errors and confidence intervals.
Mata Matters: Creating New Variables—sounds Boring, isn't
Authors: Gould William
Published: November 2018

Mata is Stata's matrix language. In the Mata Matters column, we show how Mata can be used interactively to solve problems and as a programming language to add new features to Stata. In this quarter's column, we continue to explore the handling of Stata datasets in Mata and focus on creating new variables.
Review of Regression Models for Categorical Dependent Variables Using Stata, Second Edition, by Long and Freese
Authors: Williams Richard
Published: November 2018

This article reviews Regression Models for Categorical Dependent Variables Using Stata, Second Edition, by Long and Freese.
Maximum Likelihood Estimation of Endogenous Switching and Sample Selection Models for Binary, Ordinal, and Count Variables
Authors: Miranda Alfonso , Rabe-Hesketh Sophia
Published: November 2018

Studying behavior in economics, sociology, and statistics often involves fitting models in which the response variable depends on a dummy variable—also known as a regime-switch variable—or in which the response variable is observed only if a particular selection condition is met. In either case, standard regression techniques deliver inconsistent estimators if unobserved factors that affect the response are correlated with unobserved factors that affect the switching or selection variable. Consistent estimators can be obtained by maximum likelihood estimation of a joint model of the outcome and switching or selection variable. This article describes a “wrapper” program, ssm, that calls gllamm (Rabe-Hesketh, Skrondal, and Pickles, GLLAMM Manual [University of California–Berkeley, Division of Bio-statistics, Working Paper Series, Paper No. 160]) to fit such models. The wrapper accepts data in a simple structure, has a straightforward syntax, and reports output that is easily interpretable. One important feature of ssm is that the log likelihood can be evaluated using adaptive quadrature (Rabe-Hesketh, Skrondal, and Pickles, Stata Journal 2: 1–21; Journal of Econometrics 128: 301–323).
Sequence Analysis with Stata
Authors: Brzinsky-Fay Christian , Kohler Ulrich , Luniak Magdalena
Published: November 2018

We describe a general strategy to analyze sequence data and introduce SQ-Ados, a bundle of Stata programs implementing the proposed strategy. The programs include several tools for describing and visualizing sequences as well as a Mata library to perform optimal matching using the Needleman–Wunsch algorithm. With these programs Stata becomes the first statistical package to offer a complete set of tools for sequence analysis.