Comparison of two methods of calculating concentration distributions

Summary The principal difference between concentration distributions calculated by the method of [2] and those calculated by the method of [1] is that the former show no discontinuities between the histogram peaks along the concentration axis. This indicates that the method of [2] permits calculation of distributions which are much closer to the actual ones than those found by the method of [1],The value of the total absolute difference between the distributions calculated by these methods passes through at least one maximum, as the original powder mixture is transformed into the homogeneous state.     

Comparison of two random-effects methods of meta-analysis.

Two studies compared the Schmidt-Hunter method of meta-analysis (J. E. Hunter & F. L. Schmidt, 1990) with the method described by L. V. Hedges and J. L. Vevea (1998). Study 1 evaluated estimates of ρ?, ?ρ, and resulting credibility intervals for both models through Monte Carlo methods. Results showed slight differences between the 2 methods. In Study 2, a reanalysis of published meta-analyses using both methods with several artifact distributions showed that although both choice of technique and type of correction could matter, the technique of meta-analysis used is less influential on the study outcome than is the choice of artifact correction. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Comparison of two methods of calculating quality-adjusted life years

This paper compares two methods for calculating QALYs using quality of life data from a clinical trial. The methods produced similar results in the population as a whole, but they gave different results in a large subset. Different methods for calculating QALYs may give different results, and care should be taken to select the correct method.     

两种组织脱钙法对免疫组织化学染色影响比较

目的:了解1%(体积分数)盐酸和10%(体积分数)硝酸脱钙液对多种抗原免疫组织化学染色效果的影响.方法:选择伴有灶状钙化的软组织标本包括甲状腺乳头状癌、乳腺癌、前列腺癌、结肠癌和淋巴结各3例,骨组织标本包括活检和尸检病例共9例,将样本分为3组,一组分别用10%(体积分数)硝酸处理24、42和48 h,另一组分别用1%(体积分数)盐酸处理1、2和3 h,还有一组不用酸处理作为对照组,同时进行多种抗原免疫组织化学染色,其中乳腺癌组织作ER、PR和Ki-67染色,甲状腺癌组织作TTF-1染色,前列腺癌作34βE12和P504s染色,结肠癌作AE1/AE3、P504s和Ki-67染色,淋巴结作CD3、CD20和Ki-67染色,骨组织作CD3、CD20、CD68、CD235a、MPO、Ki-67、AE1/AE3和TTF-1染色.结果:伴有钙化的软组织和骨组织内多种抗原免疫组织化学染色阳性程度均随酸处理时间的延长而有不同程度的下降,骨组织对酸处理的耐受力比软组织强;不同抗原对酸处理的敏感性不同,TTF-1和Ki-67最为敏感,ER、CD3、和CD20耐受性较好.结论:大多数情况下,盐酸和硝酸处理都会降低组织免疫组织化学染色的敏感性,但是对不同抗原的影响程度不同.大块骨组织可以采用10%(体积分数)硝酸脱钙,软组织比例较高的骨组织和骨髓活检组织尽可能使用1%(体积分数)盐酸脱钙.     

Comparison of two methods for the assessment of delayed-type hypersensitivity skin responses in patients with human immunodeficiency virus infection

We compared two techniques for detecting delayed-type hypersensitivity (DTH) skin responses in 359 patients infected with human immunodeficiency virus (HIV) (mean CD4+ lymphocyte count, 387/microL). DTH responses were assessed with use of two antigenic panels administered simultaneously: tuberculin purified protein derivative (PPD) plus three control antigens (Candida albicans, mumps antigen, and tetanus toxoid) administered by the Mantoux method and by a multiple-puncture device delivering seven antigens percutaneously (MULTITEST CMI; Institut Mérieux, Lyon, France). Eighty-three patients (23%) were anergic, 216 (60%) reacted to both panels, 55 (15%) did not react to MULTITEST CMI but did react to the antigens administered by Mantoux method, and only five (1%) reacted to MULTITEST CMI without reacting to antigens administered by the Mantoux method (P < .001, McNemar's test). Each of the three possible combinations of PPD plus two control antigens administered by the Mantoux method were also superior to MULTITEST CMI for classifying patients as nonanergic (P < .001, McNemar's test). We conclude that the application of antigens by the Mantoux method is more efficient than MULTITEST CMI for detecting DTH skin responses in HIV-infected patients.     

两种容量维方法提取化探数据异常下限效果对比

对云南某地1 850个(其中11个点水域覆盖,以0代替)水系沉积物Au元素化探数据进行含量-求和法与含量-数目法分维值计算,均表明Au含量数据存在两个无标度区,反映研究区Au元素存在两个不同层次的分布,即背景场和异常场。两者所确定的异常下限相同,但前者分维值(3.299 9和0.083 1)均大于后者分维值(2.679 2和0.013 5)。依据异常下限将异常场分解出来。Au元素异常场三维曲面图与原始数据综合场三维曲面图对比,不仅保留基本异常信息,并且突出弱异常信息,反映弱异常区不同矿化中心的叠加。Au元素背景场与异常场均存在聚集与分散双重性质。背景区金元素分布整体分散连续,局部微弱聚集,异常区整体高度聚集,局部分散连续。     

Comparison of two methods for enumerating malaria parasites in thick blood films

We evaluated the risk of brain tumor occurrence in relation to previous head injury in a population-based case-control study of 540 children with a primary brain tumor and 801 control children. The risk of a brain tumor among children with a previous head injury that resulted in medical attention was slightly elevated when compared with children with no reported head injury [odds ratio (OR) = 1.4; 95% confidence limits (CL) = 1.0, 1.9]. This effect was stronger when we restricted the head-injured group to the few children with loss of consciousness (OR = 1.6; 95% CL = 0.6, 3.9) or an overnight admission to a hospital (OR = 1.7; 95% CL 0.7, 4.6), relative to those with no head injury. We observed no appreciable association between brain tumor occurrence and birth injury involving the head or a forceps delivery. Among the few children with either a birth injury or forceps delivery and a subsequent head injury, we observed approximately twofold elevations in risk. The OR was 2.6 (95% CL = 1.1, 6.9) for those with a birth injury and subsequent head injury, relative to those with neither a birth injury nor head injury. Our results provide only weak evidence in support of head injury as an etiologic agent for brain tumor occurrence in children, although most of our exposed group had only mild head injury.     

Comparison of two rapid urease tests for detection of Helicobacter pylori infection

The selection of NIH 3T3 cells expressing a hydroxytamoxifen-inducible c-Raf-1-estrogen receptor fusion protein (c-Raf-1-BxB-ER) in the absence or presence of the inducer results in dramatic differences in the expression levels of the fusion protein. Hydroxytamoxifen-mediated constitutive activation of the Raf signal favors the selection of cells expressing low levels of c-Raf-1-BxB-ER. Cells selected in the absence of hydroxytamoxifen express up to 20 times higher levels of the inducible Raf kinase. Activation of the oncogenic Raf kinase in cells expressing low levels leads to a weak activation of the Raf/Mek/Erk cascade and the induction of S phase in confluent cells. The activation of cells expressing high levels of the kinase leads to a strong persistent signal and inhibits DNA synthesis and mitosis in proliferating cells. The inhibition of DNA synthesis and cell division is presumably due to the elevated expression of the cyclin-dependent kinase inhibitor p21cip1, similar to cells exposed to ionizing radiation. Despite the inhibition of DNA synthesis and mitosis, the constitutive activity of the Raf signaling pathway is still able to initiate cell growth. Activation of the high-intensity Raf signal in arrested serum-starved cells induces cell growth up to a size corresponding to that of M-phase cells in the absence of DNA synthesis. High-intensity Raf signals in proliferating cells consistently lead to an accumulation of cells with the size of M-phase cells and the DNA content of G1 cells or G2-M-phase cells. Therefore, the activation of Raf kinase is sufficient to drive cell growth, even in the presence of high levels of the cyclin-dependent kinase inhibitor p21cip1.     

Comparison of two methods of surfactant administration and the effect on dosing-associated hypoxemia

OBJECTIVE: The purpose of our study was to test the hypothesis that surfactant dosing through a proximal sideport adapter on an endotracheal tube leads to more dosing-associated hypoxemia compared with a method of dosing that uses a double-lumen endotracheal tube. STUDY DESIGN: Using adequate sample size to compare significant changes in O2 saturation (power > 0.8, alpha < 0.05) we enrolled 36 infants with respiratory distress syndrome in this randomized trial. A 10% change in O2 saturation was considered clinically significant. Nineteen infants received 38 doses of surfactant through the sideport adapter. Seventeen infants received 31 doses of surfactant through the nonventilation lumen of a double-lumen endotracheal tube. Two main outcome measures were assessed: time-averaged O2 saturation values 30 minutes after dosing and the largest absolute fall in O2 saturation for each patient. RESULTS AND CONCLUSIONS: Time-averaged O2 saturation measures were higher in the proximal sideport group (p = 0.02), but the magnitude of difference was probably not clinically significant. No significant difference was detected between groups when we compared largest absolute drop in O2 saturation. Secondary analyses found no effect of birth weight or dose number (second vs third dose) on either outcome measure.     

Comparison of two methods of therapy level calibration at 60Co gamma beams

The accuracy and traceability of the calibration of radiotherapy dosimeters is of great concern to those involved in the delivery of radiotherapy. It has been proposed that calibration should be carried out directly in terms of absorbed dose to water, instead of using the conventional and widely applied quantity of air kerma. In this study, the faithfulness in disseminating standards of both air kerma and absorbed dose to water were evaluated, through comparison of both types of calibration for three types of commonly used radiotherapy dosimeters at 60Co gamma beams at a few secondary and primary standard dosimetry laboratories (SSDLs and PSDLs). A supplementary aim was to demonstrate the impact which the change in the method of calibration would have on clinical dose measurements at the reference point. Within the estimated uncertainties, both the air kerma and absorbed dose to water calibration factors obtained at different laboratories were regarded as consistent. As might be expected, between the SSDLs traceable to the same PSDL the observed differences were smaller (less than 0.5%) than between PSDLs or SSDLs traceable to different PSDLs (up to 1.5%). This can mainly be attributed to the reported differences between the primary standards. The calibration factors obtained by the two methods differed by up to about 1.5% depending on the primary standards involved and on the parameters of calculation used for 60Co gamma radiation. It is concluded that this discrepancy should be settled before the new method of calibration at 60Co gamma beams in terms of absorbed dose to water is taken into routine use.     

煤干馏反应动力学的2种研究方法比较

为了深入了解COREX块煤在高温下的裂解机理,对所用块煤进行了不同温度下的高温干馏试验,确定不同温度下块煤焦油析出规律,之后分别采用混合模型法和分段法研究其干馏过程反应动力学,计算了相应的活化能和其他动力学参数.结果表明:混合模型法拟合得到3个阶段反应级数n分别为0.5、0.8、1.0,且活化能随着温度升高而增加,但由于该方法放弃反应模型物理意义,得到的只是表观活化能.分段法则根据煤干馏不同过程,确定了反应过程的机理分别为非等温收缩核、一级热解反应和分子扩散的反Jander模型,3个反应阶段的活化能分别为27.82、63.41、84.04 kJ/mol,间接地反映出块煤的裂解动力学特性,同时可为COREX熔融气化炉的数值模拟提供动力学参数.     

Comparison of two rapid whole-blood tests for Helicobacter pylori infection in Chinese patients

Consecutive Chinese patients undergoing endoscopy for dyspepsia were tested for Helicobacter pylori infection by two rapid whole-blood tests: FlexPack HP (Abbott Laboratories) and Helisal One-Step (Cortecs Diagnostics). Biopsy-based tests (rapid urease test and histology) and the [13C]urea breath test were used as the "gold standard." One hundred sixty-one consecutive patients were studied, and 88 (54.7%) were confirmed to have H. pylori infection. The sensitivities, specificities, and positive and negative predictive values were 81.8%, 83.6% (P = 0.008), 85.7% (P = 0.04), and 79.2% for FlexPack HP and 84.1%, 63.0% (P = 0.008), 73.3% (P = 0.047), and 76.7% for Helisal One-Step, respectively.     

Comparison of closed-suction drainage and no drainage after primary total knee arthroplasty

One hundred thirty-six primary total knee arthroplasty patients were randomized for the use of closed-suction, nonreinfusable wound drains. Blood loss was identical in the drained and undrained groups. Forty percent of undrained wounds compared with 0% of drained wounds required dressing reinforcement. Sixty-nine percent of undrained wounds compared with 39% of drained wounds developed ecchymosis, measuring 92 cm2 in the undrained group and 28 cm2 in the drained group. This study concludes that a simple wound drain effectively minimizes the undesirable accumulation of blood in the surrounding soft tissues and the postoperative wound dressing after total knee arthroplasty.     

The influence of surveillance methods on surgical wound infection rates in a tertiary care spinal surgery service

We studied 13 consecutive infants admitted to our Neonatal Intensive Care Unit over 37 months from 1 June 1994 to 30 June 1997, who were diagnosed with severe persistent pulmonary hypertension (PPHN) meeting extracorporeal membrane oxygenation (ECMO) criteria as defined by Bartlett and/or Short. They were managed with conservative ventilation strategy, with emphasis on the use of moderate ventilatory pressures whilst avoiding paralysis. Peak inspiratory pressure (PIP) on intermittent mandatory ventilation was adjusted according to adequate chest excursion. High PIP was avoided. Two main ventilatory techniques were used: 1) low ventilatory rate < or = 40/min, PIP 20 to 30 cmH2O, inspiratory time (IT) 0.5 seconds, positive end-expiratory pressure (PEEP) 5 cmH2O, and 2) high ventilatory rate 100/min, PEEP 0 cmH2O, IT 0.3 seconds. The aim was to keep preductal PaO2 > or = 50 mmHg. We did not sought to achieve alkalotic pH or low PaCO2. When PIP requirements exceeded 30 to 35 cmH2O, the use of an alternative rescue therapy such as pulmonary vasodilator, high frequency ventilation and/or surfactant were considered. Only 1 infant died of PPHN. Low mortality due to PPHN can be achieved using this strategy. There is a need for a randomised controlled trial to compare this strategy with other alternative treatment strategies.     

Comparison of two nonradiographic methods of predicting permanent tooth size in the mixed dentition

Human immunodeficiency virus type 2 (HIV-2) is known to be one of the agents that causes acquired immunodeficiency syndrome (AIDS). It has been present in West Africa since the 1960s and is currently epidemic there. Compared with human immunodeficiency virus type 1 (HIV-1), HIV-2 is genomically different. Furthermore, it is less prevalent worldwide than HIV-1. In West Africa, seropositive rates of HIV-2 are higher in urban versus rural communities, however, there are no gender differences. Sexual contact and vertical transmission are known modes of infectivity, though HIV-2 is less contagious than HIV-1.     

Comparison of two different PCR detection methods. Application to the diagnosis of pulmonary tuberculosis

The objectives are to assess the influence of the detection of the amplified DNA fragment on the sensitivity and specificity of the polymerase chain reaction (PCR). One hundred seventy-five sputum samples from 123 patients were processed. Sixty samples were taken from 60 subjects without tuberculosis, and the rest were taken from subjects with tuberculosis confirmed by culture. A fragment of the IS6110 sequence of Mycobacterium tuberculosis, which was detected using two different methods, was amplified. The detection methods used were a digoxigenin-labeled specific probe and chemiluminescent development and reamplification (nested PCR) combined with agarose gel electrophoresis. Sensitivity with probe detection was 75.65% and specificity 100%. Using the nested PCR technique, sensitivity rose to 93.04%, but specificity decreased to 96.6%. PCR is a quick and adequate way to diagnose pulmonary tuberculosis in cases where staining is negative yet there is a clinical suspicion of tuberculosis, even though a standardization process and large scale evaluation are still needed to determine its true usefulness.     

Comparison of continuation rates of intrauterine devices

The optimal heart rate in the immediate period following acute coronary occlusion has been controversial from the standpoint of arrhythmias and the extent of ischaemic injury. In the present study we have examined the effect of heart rate on both local myocardial contractile ability and ischaemia in 10 open chested dogs using strain gauge arches and epicardial electrograms. After sinus node destruction, atrial pacing was instituted for rate control at 100/min and increased randomly to 150, 175, and 200/min. Before coronary occlusion, total tension and rate of tension rise progressively increased at higher rates while ST segments demonstrated no significant changes. After coronary artery occlusion, total tension and rate of tension rise in the ischaemic zone decreased markedly and showed no significant change with increments in pacing rate. In the border zone, after the initial decrease in tension, pacing at 150 beats/min improved tension without a change in ST segments. However, when the rate was increased to 175 and 200 beats/min, although border zone tension increased further, ST segments rose significantly. Thus, a heart rate between 100-150/min provides the optimal range for increasing contractile ability in the nonischaemic and border zones without adversely affecting the degree of ischaemic injury.