• 제목/요약/키워드: Response bias

검색결과 317건 처리시간 0.031초

Coherent motion of microwave-induced fluxons in intrinsic Josephson junctions of HgI$_2$-intercalated Bi$_2$Sr$_2$C aCu$_2$O$_{8+x}$ single crystals

  • Kim, Jin-Hee;Doh, Yong-Joo;Chang, Sung-Ho;Lee, Hu-Jong;Chang, Hyun-Sik;Kim, Kyu-Tae;Jang, Eue-Soon;Choy, Jin-Ho
    • 한국초전도학회:학술대회논문집
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    • 한국초전도학회 2000년도 High Temperature Superconductivity Vol.X
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    • pp.65-65
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    • 2000
  • Microwave response of intrinsic Josephson junctions in mesa structure formed on HgI2-intercalated Bi2Sr2CaCu2O8+x single crystals was studied in a wide range of microwave frequency. With irradiation of 73${\sim}$76 GHz microwave, the supercurrent branch becomes resistive above a certain onset microwave power. At low current bias, the current-voltage characteristics show linear behavior, while at high current bias, the resistive branch splits into multiple sub-branches. The voltage spacing between neighboring sub-branches increase with the microwave power and the total number of sub-branches is almost identical to the number of intrinsic Josephson junctions in the mesa. All the experimental results suggest that each sub-branch represents a specific mode of collective motion of Josephson vortices generated by the microwave irradiation. With irradiation of microwave of microwave of frequency lower than 20 GHz, on the other hand, no branch splitting was observed and the current-voltage characteristics exhibited complex behavior at hlgh blas currents. This result can be explained in terms of incoherent motion of Josephson vortices generated by non-uniform microwave irradiation.

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Short-course Versus Long-course Preoperative Radiotherapy plus Delayed Surgery in the Treatment of Rectal Cancer: a Meta-analysis

  • Liu, Shi-Xin;Zhou, Zhi-Rui;Chen, Ling-Xiao;Yang, Yong-Jing;Hu, Zhi-De;Zhang, Tian-Song
    • Asian Pacific Journal of Cancer Prevention
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    • 제16권14호
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    • pp.5755-5762
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    • 2015
  • Background: Short-course preoperative radiation (SCRT) with delayed surgery was found to increase pathologic complete response (pCR) rates in several trials. However, there was no clear answer on whether SCRT or long-course chemo-radiotherapy (LCRT) is more effective. Therefore we conducted this meta-analysis to evaluate the safety and efficacy of SCRT versus LCRT, both with delayed surgery, for treatment of rectal cancer. Materials and Methods: The literature was searched from PubMed, EMBASE, Web of Science, Cochrane Library and clinicaltrials.gov up to November, 2014. Quality of the randomized controlled trials (RCTs) was evaluated according to the Cochrane's risk of bias tool of RCT. The Grading of Recommendations Assessment, Development and Evaluation (GRADE) system was used to rate the level of evidence. Review Manager 5.3 was employed for statistical analysis. Pooled risk ratios (RRs) and 95% confidence intervals (CIs) were calculated. Results: Three RCTs, with a total of 357 rectal cancer patients, were included in this systematic review. Metaanalysis results demonstrated there were no significantly differences in sphincter preservation rate, local recurrence rate, grade 3~4 acute toxicity, R0 resection rate and downstaging rate. Compared with SCRT, LCRT was associated with significant increase in the pCR rate [RR=0.49, 95%CI (0.31, 0.78), P=0.003]. Conclusions: In terms of sphincter preservation rate, local recurrence rate, grade 3~4 acute toxicity, R0 resection rate and downstaging rate, SCRT with delayed surgery is as effective as LCRT with delayed surgery for management of rectal cancer. LCRT significantly increased pCR rate compared with SCRT. Due to risk of bias and imprecision, further multi-center large sample RCTs were needed to confirm this conclusion.

Whole Brain Radiotherapy Plus Chemotherapy in the Treatment of Brain Metastases from Lung Cancer: A Meta-analysis of 19 Randomized Controlled Trails

  • Liu, Wen-Jing;Zeng, Xian-Tao;Qin, Hai-Feng;Gao, Hong-Jun;Bi, Wei-Jing;Liu, Xiao-Qing
    • Asian Pacific Journal of Cancer Prevention
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    • 제13권7호
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    • pp.3253-3258
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    • 2012
  • Objective: To evaluate the efficacy and safety of whole brain radiotherapy (WBRT) plus chemotherapy versus WBRT alone for treating brain metastases (BM) from lung cancer by performing a meta-analysis based on randomized controlled trials (RCTs). Methods: The PubMed, Embase, CENTRAL, ASCO, ESMO, CBM, CNKI, and VIP databases were searched for relevant RCTs performed between January 2000 and March 2012. After quality assessment and data extraction, the meta-analysis was performed using the RevMan 5.1 software, with funnel plot evaluation of publication bias. Results: 19 RCTs involving 1,343 patients were included. The meta-analyses demonstrated that compared to WBRT alone, WBRT plus chemotherapy was more effective with regard to the objective response rate (OR = 2.30, 95% CI = 1.79 - 2.98; P < 0.001); however, the incidences of gastrointestinal reactions (RR = 3.82, 95% CI = 2.33 - 6.28, P <0.001), bone marrow suppression (RR = 5.49, 95% CI = 3.65 - 8.25, P < 0.001), thrombocytopenia (RR = 5.83, 95% CI = 0.39 - 86.59; P = 0.20), leukopenia (RR = 3.13, 95% CI = 1.77 - 5.51; P < 0.001), and neutropenia (RR = 2.75, 95% CI = 1.61 - 4.68; P < 0.001) in patients treated with WBRT plus chemotherapy were higher than with WBRT alone. There was no obvious publication bias detected. Conclusion: WBRT plus chemotherapy can obviously improve total efficacy rate, butalso increases the incidence of adverse reactions compared to WBRT alone. From the limitations of this study, more large-scale, high-quality RCTs are suggested for further verification.

우리나라 노동조합이 여성근로자의 임금에 미치는 영향 (An Analysis of the Effects of Unions on Wages for Female Workers)

  • 신우리;송헌재
    • 노동경제논집
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    • 제39권3호
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    • pp.99-124
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    • 2016
  • 본 연구는 한국노동패널 자료를 사용하여 노동조합이 우리나라 여성근로자들의 임금에 미치는 영향을 실증분석하였다. 분석에는 여성근로자들의 임금함수 추정과정에서 경제활동참여에 의한 선택편의를 고려하였고, 종업원 수가 무응답인 경우 그 값을 보정하여 분석하였으며, 직장에 노동조합이 있고 노동조합에 가입한 조합원 근로자와 가입하지 않은 비조합원 근로자를 직장에 노동조합이 없는 근로자와 비교하여 분석하였다. 그 결과, 고정효과 모형 추정에서 조합원 및 비조합원 더미변수 모두 통계적으로 유의하지 않은 것으로 나타났다. 이로부터 OLS 모형 추정에서 나타난 노동조합의 임금효과는 능력이 높은 여성근로자들이 유노조 사업체에 취업하는 것을 더 선호한 결과이며, 비조합원의 무임승차 효과는 없다고 보는 것이 타당하다는 결론을 도출하였다.

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한 인구학도의 회고

  • 김택일
    • 한국인구학
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    • 제11권1호
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    • pp.1-13
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    • 1988
  • 여기서는 많은 수의 비관측사례로부터 발생할 수 있는 표본의 편의(bias) 문제를 탐구한다. 이 연구는 본래 일본 후생성이 1989년 실시한 <가족주기와 가구형태에 대한 인구학적 조사> 자료를 이용하여 노인부보와 자녀간 근접성을 분석하는 목적에서 이루어졌다. 그런데 <가족주기와 가구형태에 대한 인구학적 조사>는 노인부모를 대상으로 한 조사가 아니라 전체 가구 일반에 대한 조사이기 때문에 노인부모에 대한 많은 정보를 손상하고 있었다. 또한 본 조사는 가구주를 통하여 가족원에 대한 정보를 획득하는 방식으로 설계되었기 때문에 가족원에 대한 정보가 완전하지 못하였다. 나아가 비관측사례의 유형을 보면 여러 항목들이 동시적으로 관측되지 않고 있었다. 이와 같이 복합적 메커니즘에서 발생한 비관측 사례는 분석의 편의를 초래할 위험이 크다. 우선, 많은 수의 비관측사례로 표준오차를 잘못 추정할 소지가 크다. 더욱이 사례들이 선택적으로 관측되지 않았다면 관측된 자료에 따른 추정을 심각한 편의를 포함할 수 있다. 이와 같이 손상된 자료로부터 발생할 수 있는 추정 편의를 개선하기 위하여 여기서는 두 가지 기법을 활용하였다. 첫째, 관측치와 공변인간의 관계에 기초하여 비관측사례를 추정하는 방법으로 EM 알고리듬을 활용하였다. 둘째, 관찰의 선택성에서 비롯된 추정 편의를 개선하기 위하여 이단계(two stage) 모형을 활용하였다.

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소화성 궤양에 대한 오패산의 치료효과 : 체계적 문헌고찰과 메타분석 (The Effect of Opae-san for Peptic Ulcer Disease: A Systematic Review and Meta-Analysis)

  • 이유리;조나경;김경순;최홍식;김승모
    • 대한한방내과학회지
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    • 제39권6호
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    • pp.1136-1149
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    • 2018
  • Objectives: The aim of this study was to perform a meta analysis of randomized controlled trials (RCTs) that applied Opae-san to peptic ulcer. Methods: The databases NDSL, RISS, KISS, KISTI, Oasis, DBpia, Cochrane, EMBASE, Pubmed, and CNKI were searched to identify RCTs that evaluated the therapeutic response to Opae-san on peptic ulcer. The selected studies were assessed using Cochrane Group's risk of bias tool. Results: 12 RCTs were selected from a total of 312 identified. Combined therapies of Opae-san plus triple therapy were superior to only triple therapy in achieving the effective rate (risk ratio=1.26, 95% CI: 1.17 to 1.35, p<0.001, I2=0%), the helicobacter pylori eradication rate (risk ratio=1.23, 95% CI: 1.12 to 1.34, p<0.001, I2=7%) and the recurrence rate (risk ratio=0.31, 95% CI: 0.12 to 0.82, p=0.02, I2=0%). But only Opae-san was not superior in achieving the effective rate compared to anti gastric secretion drugs. Conclusions: The current evidence suggests that combined therapies of Opae-san plus triple therapy yield a higher effective rate, and helicobacter pylori eradication rate and a lower recurrence rate. However, in most of these studies, it is difficult to evaluate the bias and therefore better designed studies are needed.

Effects of the Nuegra from Male Silkworm Extract on Enhancement of the Masculine Function and Activation of Overall Physical Function

  • Kim, D. C.;Kim, Y. W.;Park, M. S.;J. K. Suh;Lee, D. S.;Lee, S. H.;B. H. Chun;Y. K. Jun
    • International Journal of Industrial Entomology and Biomaterials
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    • 제5권1호
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    • pp.109-122
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    • 2002
  • The purpose of this investigation is to evaluate the effects of the Nuegra on enhancement of the masculine and physical activities in general through measuring changes of the testosterone, FSH and subjective symptoms like fatigue, insomnia, urinary stream, muscular weakness, libido and erectile dysfunction. Total 168 male subjects were enrolled from 12 urology, internal medicine clinics and general practitioner, During the 6-week investigational period, 2 capsules of Nuegra were given to the subjects right after meal for 4 weeks, and 1 capsule of Nuegra was added each time in subjects with no or minimal effect. Testoster-one and FSH levels were measured at first visit and last visit, for evaluating masculine activities. To avoid bias and standardize the test results, only one clinic was assigned as a central lab, and all blood samples were transferred. General information and subjective symptoms were evaluated at first visit and at 2 weeks interval, week 2, 4 and 6 using VAS (Visual Analogue Scale). The mean age of the subjects were 51.8${\pm}$8.2 years old (range: 36.1-82.1). Based on the subjects who were tested on testosterone and FSH levels at day l and week 6, the means were 4.4${\pm}$1.4 nmol/L (range: 2.6-7.7), 8.6${\pm}$9.6 mIU/mL (range: 0.3-40.4), respectively at day 1. At week 6, the results were 4.9 ${\pm}$1.6 (2.6-8.9 range), 9.4${\pm}$13.1 (1.0-53.9 range), respectively. Marginally significant difference between pre-dose and post-dose was present. Statistically significant differences were revealed in general assessment for subjective symptoms, fatigue, insomnia, erectile dysfunction, etc. In fatigue, response rates were 39.6, 65.4 and 76.4% at week 2, 4 and 6, respectively (P < 0.0001). Response vates for erectile dysfunction were 13.4, 41.2 and 72.7% at week 2, 4, and 6 (P < 0.0001), respectively, Response rates for libido were 13.6, 51.6 and 73.5% at week 2, 4, and 6 (P < 0.0001), respectively. For urinary stream response rates were 26.9, 44.7 and 66.8% at week 2, 4, and 6 (P < 0.0001), respectively. VAS for muscular weakness did not show significant results that response rates were 40, 60 and 80% at week 2, 4, and 6 from 8.2 (P = 0.24), respectively. Response rates for insomnia were 50, 60, 100% at week 2, 4, and 6 (P < 0.0001), respectively. The results shows that Nuegra tends to enhance masculine activities including libido, erectile dysfunction and urinary stream and also effective for improving general conditions especially insomnia, muscular weakness and fatigue. In conclusion, this investigation has demonstrated that Nuegra does not only have tendency to increase masculine activities through increased secretion of the testosterone and FSH but also improve general conditions such as erectile dysfunction, libido, fatigue and muscular power.

과학학습의 정의적 영역에서 사전-사후 통합 검사 설계의 타당화 연구: 과학영재를 대상으로 (A Validation Study of Retrospective Pre-post Testin the Affective Domain in Science Learning:for Scientifically Gifted Elementary Students)

  • 임채성;박형민
    • 한국초등과학교육학회지:초등과학교육
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    • 제36권3호
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    • pp.219-226
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    • 2017
  • In this study, the reliability and validity of the retrospective pre-post test were analyzed in order to solve the problem of traditional pre-post test including response shift bias. Samples of the study were 162 elementary school students who are studying at the S university gifted education center in Seoul. Before completion of the field trip, we conducted pre test of science-related attitudes. After completion of the field trip, respondents were asked to compare their responses of pre and post science-related attitudes to quantitatively analyze the commonalities and differences of the two tests. To find out more characteristics, qualitative data such as daily records and interview were also gathered and analyzed. The major results of the study are as follows. First, for the paired t-test, there was no statistically significant difference between separate pre-test scores and retrospective pre-test. There was a very high correlation between the separate pre-test scores and the retrospective pre-test. Second, there were significant differences in all seven sub-factors of science-related attitudes between the retrospective pre-test and the post-test. Third, the separate pre-test scores showed a slightly higher tendency than the retrospective pre-test scores. This suggests that the response shift bias appears when it is performed the separate pre-test in affective domain. As a result of the interview, it was found that the evaluation standards of separate pre-test did not match with those of post-test. Forth, internal consistency reliability of the retrospective pre-test was higher than that of the separate pre-test. However, there were significant differences in six factors of science-related attitudes excluding the 'social implications of science' between the separate pre-test and the post-test. Based on these results, the retrospective pre-post test design provides simplicity and convenience to both respondents and investigators, as it is done with one test. The retrospective pre-post test design can be regarded as a valid design for the self-report measurement of affective domain on a single experimental group.

유해화학물질 대기확산 예측을 위한 RAMS 기상모델의 적용 및 평가 - CARIS의 바람장 모델 검증 (Application and First Evaluation of the Operational RAMS Model for the Dispersion Forecast of Hazardous Chemicals - Validation of the Operational Wind Field Generation System in CARIS)

  • 김철희;나진균;박철진;박진호;임차순;윤이;김민섭;박춘화;김용준
    • 한국대기환경학회지
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    • 제19권5호
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    • pp.595-610
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    • 2003
  • The statistical indexes such as RMSE (Root Mean Square Error), Mean Bias error, and IOA (Index of agreement) are used to evaluate 3 Dimensional wind and temperature fields predicted by operational meteorological model RAMS (Regional Atmospheric Meteorological System) implemented in CARIS (Chemical Accident Response Information System) for the dispersion forecast of hazardous chemicals in case of the chemical accidents in Korea. The operational atmospheric model, RAMS in CARIS are designed to use GDAPS, GTS, and AWS meteorological data obtained from KMA (Korean Meteorological Administration) for the generation of 3-dimensional initial meteorological fields. The predicted meteorological variables such as wind speed, wind direction, temperature, and precipitation amount, during 19 ∼ 23, August 2002, are extracted at the nearest grid point to the meteorological monitoring sites, and validated against the observations located over the Korean peninsula. The results show that Mean bias and Root Mean Square Error are 0.9 (m/s), 1.85 (m/s) for wind speed at 10 m above the ground, respectively, and 1.45 ($^{\circ}C$), 2.82 ($^{\circ}C$) for surface temperature. Of particular interest is the distribution of forecasting error predicted by RAMS with respect to the altitude; relatively smaller error is found in the near-surface atmosphere for wind and temperature fields, while it grows larger as the altitude increases. Overall, some of the overpredictions in comparisons with the observations are detected for wind and temperature fields, whereas relatively small errors are found in the near-surface atmosphere. This discrepancies are partly attributed to the oversimplified spacing of soil, soil contents and initial temperature fields, suggesting some improvement could probably be gained if the sub-grid scale nature of moisture and temperature fields was taken into account. However, IOA values for the wind field (0.62) as well as temperature field (0.78) is greater than the 'good' value criteria (> 0.5) implied by other studies. The good value of IOA along with relatively small wind field error in the near surface atmosphere implies that, on the basis of current meteorological data for initial fields, RAMS has good potentials to be used as a operational meteorological model in predicting the urban or local scale 3-dimensional wind fields for the dispersion forecast in association with hazardous chemical releases in Korea.

부정자극 지각에 관련된 불안인과 정상인의 공간주의 비교연구 (Different mechanism of visual attention in anxious and non-anxious population)

  • 최문기;구민모;박건우;남기춘
    • 인지과학
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    • 제20권1호
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    • pp.51-77
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    • 2009
  • 많은 연구들은 부정과년 자극의 처리가 그 처리자의 정서 상태에 따라 다른 처리가 이루어진다는 것을 주장하였다. 정서 정보 지각의 특성은 크게 두 가지 가정에 의해 논의되었다: 주의 결속(attentional engagement)에서의 차이와 주의해제(attentional disengagement)에서의 차이. 본 연구는 Posner의 cue-target 실험 패러다임을 이용하여 정서 정보 지각이 일반 자극의 지각과 어떠한 위치에서 차이가 나는지를 규명하고자 하였다. 단어 자극을 사용한 실험1과 얼굴 자극을 사용한 실험 2 모두에서 기존의 Fox(2001)에서 나온 결과와는 다르게 정서 자극의 지각이 일반자극의 지각에 비해 주의 결속에서 빠른 반응을 나타냈으며, 이런 경향성은 불안 수준이 높은 피험자에게서만 관찰되었다. 또한, 불안 수준이 높은 피험자들은 일반 피험자들 보다 단서와 목표자극이 일치되는 조건에서 느린 반응을 보였다. 실험 1과 2의 결과가 이 효과와 정서의 혼입되어 나온 결과인가에 대한 통제 실험을 시행한 실험 3에서는 정서 자극 제시 없이 일치 불일치에 대한 결과만을 보았다. 실험 3의 결과는 실험 1과 2가 정서와 피험자의 정서 상태에 의한 결과임을 지지하였다. 따라서 본 연구는 불안이라는 정서 상태가 부정적인 자극에 대한 지각을 빠르게 하는 이유가 정서 자극에 대한 빠른 주의결속이 있기 때문임을 지지하고 있다.

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