Is there a real diagnostic impact of elastosonography and contrast-enhanced ultrasonography in the management of thyroid nodules?

Ultrasonography(US) and the new applications US elastography(USE) and contrast-enhanced US(CEUS) are used in the screening of thyroid nodules,for which fine-needle aspiration biopsy(FNAB) is the best single diagnostic test.The aim of the study was to compare the sensitivity,specificity,positive predictive value(PPV),and accuracy of the four examinations in nodules with cytological and histological diagnoses.The study used data from US,FNAB,USE(elasticity(ELX 2/1) index),and CEUS(Peak index and time to peak(TTP) index) evaluated in 73 thyroid nodules in 63 consecutive patients likely to undergo surgery.Cytological-histological correlation was available for 38 nodules.No correlation emerged between nodule size and cytological results.A significant(P=0.03) positive correlation between cumulative US findings and cytological results was found.In addition,significant correlations between cumulative US findings and cytology(P=0.02) and between cumulative US findings and histology(P<0.0001) were found.US showed the best specificity and PPV,and FNAB the best sensitivity.There was no significant difference in the ELX 2/1 index,Peak index,or TTP index among nodules subdivided according to cytological scores.No significant correlation was found between ELX 2/1 index,Peak index,and TTP index,on the one hand,and nodule size,US cumulative findings,cytology,and histology on the other hand.The sensitivity of the ELX 2/1 index was high,but its specificity was very low.The accuracy and PPV of USE were lower than those of the other procedures.Only the correlation between Peak index and cumulative US findings reached a value close to significance.Our ultimate aim is to minimise unnecessary thyroidectomy.US and FNAB continue to play a central diagnostic role.The use of a US score showed high specificity and PPV.The specificity of FNAB was low in this selected series because of the numbers of indeterminate cytological responses.USE and CEUS are innovative techniques that need to be standardized.The ELX 2/1 index,Peak index,and TTP index seem to be unrelated to histology.The best statistical data on USE and CEUS concerned their sensitivity and PPV,respectively.At present,USE and CEUS are too time-consuming and of limited utility in selecting patients for surgery.     

Preoperative localization and minimally invasive management of primary hyperparathyroidism concomitant with thyroid disease

The coexistence of thyroid diseases with primary hyperparathyroidism （PHPT） can present a challenge in the clinical diagnosis and management for these patients. This study aims to determine the frequency of coexisting thyroid gland lesions in a consecutive series patients with PHPT, and to analyze the clinical features, diagnosis and treatment of these patients. Twenty-two cases of a total of 52 PHPT patients who had synchronous thyroid and parathyroid pathology were surgically managed in this study Thirteen patients had ipsilateral thyroid nodules, and 9 patients had thyroid nodules in contralateral or bilateral side. Seven patients underwent direct parathyroidectomy and hemithyroidectomy via a mini-incision （about 3 cm）, while other 15 procedures were converted to Kocher incision. Seventeen nodular goiter （32.7%）, 2 thyroiditis （3.8%）, 2 thyroid adenoma （3.8%） and 1 thyroid carcinoma （1.9%） coexisting with parathyroid adenoma were pathologically diagnosed. The sensitivity of preoperative ultra- sonography （US） and methoxy-isobutyl-isonitrile （MIBI） scintigraphy for parathyroid lesions was 63.6% and 85.7%; and the overall positive predictive values for MIBI and US were 100% and 95.5% respectively. A high incidence of thyroid diseases that coexisted with PHPT in literatures was briefly reviewed. Our study illustrated the need for clinical awareness of concomitant PHPT and thyroid disease. A combination of US, computed tomography （CT） and MIBI scintigraphy would be recommended for preoperative localization of enlarged parathyroid adenoma and for evaluation of thyroid lesions. Synchronous treatment of associated thyroid abnormalities is desirable, and open minimally invasive surgical approach with additional resection of isolated ipsilateral thyroid nodules is possible in some of these patients.     

Use of interactive live digital imaging to enhance histology learning in introductory level anatomy and physiology classes

Histology is one of the main subjects in introductory college-level Human Anatomy and Physiology classes. Institutions are moving toward the replacement of traditional microscope-based histology learning with virtual microscopy learning amid concerns of losing the valuable learning experience of traditional microscopy. This study used live digital imaging (LDI) of microscopic slides on a SMART board to enhance Histology laboratory teaching. The interactive LDI system consists of a digital camera-equipped microscope that projects live images on a wall-mounted SMART board via a computer. This set-up allows real-time illustration of microscopic slides with highlighted key structural components, as well as the ability to provide the students with relevant study and review material. The impact of interactive LDI on student learning of Histology was then measured based on performance in subsequent laboratory tests before and after its implementation. Student grades increased from a mean of 76% (70.3-82.0, 95% CI) before to 92% (88.8-95.3, 95% CI) after integration of LDI indicating highly significant (P < 0.001) enhancement in students' Histology laboratory performance. In addition, student ratings of the impact of the interactive LDI on their Histology learning were strongly positive, suggesting that a majority of students who valued this learning approach also improved learning and understanding of the material as a result. The interactive LDI technique is an innovative, highly efficient and affordable tool to enhance student Histology learning, which is likely to expand knowledge and student perception of the subject and in turn enrich future science careers.     

Unwanted and illegal sexual experiences in childhood and adolescence

Three hundred forty-two anonymous surveys regarding unwanted sexual experiences (USE) were filled out in three clinic sites: a pediatric sexual abuse clinic, family practice clinic, and family planning clinic. In the latter two clinics, 40% of females and 16% of males had at least one unwanted sexual experience prior to turning 18 years old. Only 91% of the sexual abuse clinic patients indicated their experience was unwanted. In addition, 27% of the subjects had wanted sexual experiences that were illegal and underreported: These experiences involved a partner at least 4 years older or younger. While feelings of victimization were most common, self-blame and naivete about the abuse were also frequently reported, especially in those who had an USE with a peer. Ambivalence, self-blame, and peer pressure were associated with a lower tendency to disclose one's USE. Although unwanted and illegal sexual experiences were less common in Hispanic females, feelings of self-blame and ambivalence regarding their USE were more frequent in comparison with White females. These findings have important investigative and therapeutic implications for professionals who encounter victims of sexual abuse.     

Disclosing unwnated sexual experiences: results from a national sample of adolescent women

OBJECTIVE: The aims of this study are to identify factors that influence the disclosures made by female survivors of unwanted sexual experiences (USE) in childhood and adolescence. The predictors of both the timing of disclosure (short delay, long delay, non-disclosure) and the recipient of the disclosure (disclosing ever to an adult, disclosing to peers only, non-disclosure) were investigated. Participant characteristics, USE characteristics, and family contextual variables were explored. METHOD: A sub-sample of 263 adolescent females who reported unwanted sexual experiences in the National Survey of Adolescents (NSA) provided data on the characteristics of their experience as well as the timing and recipients of disclosure. Two multinomial logistic regression analyses were conducted to determine significant predictors of each aspect of disclosure. RESULTS: Age of onset, a known perpetrator, a familial relationship with the perpetrator, and a history of drug abuse in the household are related to the timing of disclosure. Age of onset, penetration, fear for one's life during the USE, injury during the USE, family structure, and the age differential between the survivor and the perpetrator are linked to the recipient of the disclosure. CONCLUSION: Age is a critical variable in the disclosure process. Whereas aspects of the abuse experience were more important in predicting whom a victim would tell, the relationship to the perpetrator was more important in deciding to delay disclosure. As survivors grow into adolescence, the importance of peers provides a source of support that becomes increasingly important in decisions to disclose.     

Universal secondary education in Uganda: The head teachers’ dilemma

Uganda has received considerable international attention for being the first and, to date, only African country to adopt a policy of free universal secondary education (USE). However, the policy was adopted with little attention to system capacity or involvement of secondary head teachers, even though there is considerable research documenting the importance of school leaders in promoting or blocking education reform efforts. This study investigated the extent to which Uganda secondary school leaders support USE policy, the extent they think USE is being implemented successfully, and the extent they believe they have the knowledge and skills needed in USE implementation. To understand the role of head teachers in the move to USE in Uganda, it is necessary to understand the political context in which it was adopted and the conditions under which it was implemented.     

Institutional experience of PTH evaluation on fine-needle washing after aspiration biopsy to locate hyperfunctioning parathyroid tissue

Assaying parathyroid hormone (PTH) in the washing liquid after fine-needle aspiration biopsy (FNAB) seems to be a valid approach to locate parathyroid tissue. PTH-FNAB was evaluated in 47 patients with a clinical picture of primary hyper-parathyroidism (PHP) and ultrasonography (US) suggestive of parathyroid lesion. The patients were subdivided into two groups on the basis of the absence or presence of US thyroid alterations. The result of PTH-FNAB was compared with those of cytology, scintigraphy and, in 24 patients, surgical outcome. PTH-FNAB samples with a value higher than that recorded in the serum and higher than our institutional cut-off were deemed to be probable samples of parathyroid tissue. Cytology proved diagnostic for benign thyroid lesions, non-diagnostic for thyroid lesions, hyperplastic parathyroid tissue, undetermined or malignant thyroid lesions and other lesions in 45%, 30%, 17%, 4%, and 4% of cases, respectively. In 47% of cases, PTH-FNAB indicated that the sample had been taken in parathyroid tissue. In patients without US alterations, the diagnostic accuracy of PTH-FNAB was greater than that of scintigraphy. After surgery, comparison between the results of PTH-FNAB and scintigraphy, in terms of positive predictive value (PPV), revealed the superiority of PTH-FNAB; PPV was 94% for FNAB and 71% for scintigraphy, while sen-sitivity was 83% and 69%, respectively. PTH-FNAB evaluation after FNAB appears to be more diagnostic than cytology and scintigraphy. Of all the procedures used, PTH-FNAB appears to be the method of choice when the target is US suggestive and reachable. PTH-FNAB appears to be a useful method of guiding surgical intervention.     

Socio-economic predictors of student mobility in Russia

ABSTRACT

This paper analyses the determinants of national student mobility under the unified system of admission in Russia and evaluates the barriers which still limit educational mobility. It is argued that even with the Unified State Examination (USE) and the decreased transaction costs of applying to universities, student interregional national mobility is directed towards more developed regional educational markets and richer regions, but is still limited due to the financial constraints in the absence of the additional student support. Russia is an interesting case, because it consists of regions with highly variable socio-economic development and it represents local higher education markets with different levels of competition between universities, which may influence the decision to move. USE was intended to mitigate against these differences, and for political reasons under USE such differences are not considered the main barriers of access to higher education. However, this study takes into account the importance of the institutional characteristics of regions in student mobility.     

The association between maltreatment and obesity among preschool children

OBJECTIVE: To determine whether child maltreatment is associated with obesity in preschool children. METHODS: Data were obtained from the Fragile Families and Child Wellbeing Study, a birth cohort study of 4898 children born between 1998 and 2000 in 20 large US cities. At 3 years of age, 2412 of these children had their height and weight measured, and mothers answered items on the Parent-Child Conflict Tactics Scales about three types of child maltreatment--neglect, corporal punishment, and psychological aggression. The frequency of each type of maltreatment behavior in the prior year was analyzed using categories--ever/never for neglect and quintiles for the other two types of maltreatment. Child obesity was defined as measured body mass index (kg/m(2)) > or =95th percentile. RESULTS: Eighteen percent of the children were obese, and the prevalence of any episode of neglect, corporal punishment, and psychological aggression was 11%, 84%, and 93%, respectively. The odds of obesity were increased in children who had experienced neglect (odds ratio 1.56, 95% confidence interval, 1.14-2.14), after controlling for the income and number of children in the household, the mothers' race/ethnicity, education, marital status, body mass index, prenatal smoking, and age, and the children's sex and birth weight. Neither the frequency of corporal punishment nor psychological aggression was associated with an increased risk of obesity. CONCLUSIONS: In a sample of preschool children from 20 large US cities, maternal self-report of neglectful behavior was associated with an increased risk of childhood obesity, after controlling for birth weight, maternal obesity, and multiple socioeconomic factors.     

CS and US duration effects in one-trial simultaneous fear conditioning as assessed by conditioned suppression of licking in rats

In three experiments, rats received a single presentation of an auditory conditioned stimulus (CS) beginning simultaneously with an electric grid-shock unconditioned stimulus (US). Later, the CS was presented while the rats licked a drinking tube for water, and CS-elicited suppression of licking was taken as an index of the excitation conditioned to the CS. It was found that conditioning increased as a joint function of the duration of CS-US overlap and US duration. The evidence suggested that weak conditioning due to a brief CS-US overlap could be increased by extending the US beyond CS termination. Extending CS duration beyond US termination, however, did not strengthen conditioning; indeed, extending the CS 60 sec beyond US termination weakened conditioning significantly. It is suggested that these results shed light on a discrepancy in the recent literature on simultaneous conditioning.     

Russian/US comparison using the expert science teaching educational evaluation model (ESTEEM)

A small group of Russian teachers who were interested in adopting aspects of the US science educational reform movement, participated in a constructivist science teaching project. Baseline data from translated classroom observations were scored using the science classroom observation rubric from the expert science teaching educational evaluation model (ESTEEM) and compared with a traditional (teacher centered) group of US science teachers and a group of US constructivist (student centered) science teachers. The purpose of the research is to investigate how Russian teachers who were beginning a US science education reform project compared with two US groups of science teachers, a traditional and a reform group. Analysis of variance was used to analyse the total rubric score and four categories for the Russian/traditional US and the Russian/constructivist US studies in order to examine closely the traditional and the constructivist teaching practises. In the first study US traditional teachers were statistically higher on 'facilitating the learning process' and 'context-specific pedagogy'. Russian teachers were higher on the 'content' category. In the second study the experienced constructivist US teachers were statistically higher on all four categories and the total rubric score. The educational culture of both countries is very traditional. However, the reform movement in science education has changed some US teachers, and is in the process of changing some Russian teachers. Both countries are working on the reform process. The results of this study provide baseline information on a small group of Russian teachers, who have chosen to be a part of the ideas contained in the US science education reform movement. The study also promotes the mutual understanding of both cultures among teachers, administrators, and researchers, which should ultimately form a bond for working together on common educational issues.     

One-trial simultaneous and backward fear conditioning as reflected in conditioned suppression of licking in rats

In three experiments, groups of albino rats received one strictly simultaneous pairing of a 4-sec auditory conditioned stimulus (CS) and a 4-sec 1-mA shock unconditioned stimulus (US). Other groups received a backward pairing, in which the US began before the CS, or a forward pairing, in which the CS began before the US. Control groups received only the US or received both the CS and the US but widely separated in time. Later, the CS was presented while the rats licked a drinking tube for water, and CS-elicited suppression of licking was taken as an index of the Pavlovian conditioned response (CR). It was found that groups receiving a single forward or a single simultaneous pairing suppressed more than groups that had received a backward pairing; and the backward groups, in turn, suppressed more than the control groups. It appears, then, that excitatory fear conditioning, as reflected in conditioned suppression of licking in rats, can be produced in a single trial by both backward and simultaneous conditioning procedures.     

Estimating the probability of abusive head trauma after abuse evaluation

BackgroundEvidence-based, patient-specific estimates of abusive head trauma probability can inform physicians’ decisions to evaluate, confirm, exclude, and/or report suspected child abuse.ObjectiveTo derive a clinical prediction rule for pediatric abusive head trauma that incorporates the (positive or negative) predictive contributions of patients’ completed skeletal surveys and retinal exams.Participants and Setting500 acutely head-injured children under three years of age hospitalized for intensive care at one of 18 sites between 2010 and 2013.MethodsSecondary analysis of an existing, cross-sectional, prospective dataset, including (1) multivariable logistic regression to impute the results of abuse evaluations never ordered or completed, (2) regularized logistic regression to derive a novel clinical prediction rule that incorporates the results of completed abuse evaluations, and (3) application of the new prediction rule to calculate patient-specific estimates of abusive head trauma probability for observed combinations of its predictor variables.ResultsApplying a mean probability threshold of >0.5 to classify patients as abused, the 7-variable clinical prediction rule derived in this study demonstrated sensitivity 0.73 (95% CI: 0.66-0.79) and specificity 0.87 (95% CI: 0.82-0.90). The area under the receiver operating characteristics curve was 0.88 (95% CI: 0.85-0.92). Patient-specific estimates of abusive head trauma probability for 72 observed combinations of its seven predictor variables ranged from 0.04 (95% CI: 0.02-0.08) to 0.98 (95% CI: 0.96-0.99).ConclusionsSeven variables facilitate patient-specific estimation of abusive head trauma probability after abuse evaluation in intensive care settings.     

Nutritional evaluation of caseins and whey proteins and their hydrolysates from Protamex

Whey protein concentrate （WPC 80） and sodium caseinate were hydrolyzed by Protamex to 5%, 10%, 15%, and 20% degree of hydrolysis （DH）. WPC 80, sodium caseinate and their hydrolysates were then analyzed, compared and evaluated for their nutritional qualities. Their chemical composition, protein solubility, amino acid composition, essential amino acid index （EAA index）, biological value （BV）, nutritional index （NI）, chemical score, enzymic protein efficiency ratio （E-PER） and in vitro protein digestibility （IVPD） were determined. The results indicated that the enzymatic hydrolysis of WPC 80 and sodium caseinate by Protamex improved the solubility and IVPD of their hydrolysates. WPC 80, sodium caseinate and their hydrolysates were high-quality proteins and had a surplus of essential amino acids compared with the FAO/WHO/UNU （1985） reference standard. The nutritive value of WPC 80 and its hydrolysates was superior to that of sodium caseinate and its hydrolysates as indicated by some nutritional parameters such as the amino acid composition, chemical score, EAA index and predicted BV. However, the E-PER was lower for the WPC hydrolysates as compared to unhydrolyzed WPC 80 but sodium caseinate and its hydrolysates did not differ significantly. The nutritional qualities of WPC 80, sodium caseinate and their hydrolysates were good and make them appropriate for food formulations or as nutritional supplements.     

Systematic review of laparoscopy-assisted versus open gastrectomy for advanced gastric cancer

Objective

The study compared laparoscopy-assisted gastrectomy (LAG) with open gastrectomy (OG) in the management of advanced gastric cancer (AGC).

Methods

Literature search was performed in the Medline, Embase, and Cochrane Library databases to identify control studies that compared LAG and OG for AGC. A meta-analysis was conducted to examine the surgical safety and oncologic adequacy, using the random-effect model.

Results

Seven eligible studies including 815 patients were analyzed. LAG was associated with less blood loss, less use of analgesics, shorter time of flatus and periods of hospital stay, but longer time of operation. The incidence of most complications was similar between the two groups. However, LAG was associated with a lower rate of pulmonary infection (odds ratio (OR) 0.19; 95% confidence interval (CI) 0.05 to 0.68; P<0.05). No significant differences were noted in terms of the number of harvested lymph nodes (weighted mean difference (WMD) 1.165; 95% CI–2.000 to 4.311; P>0.05), overall mortality (OR 0.65; 95% CI 0.39 to 1.10; P>0.05), cancer-related mortality (OR 0.64; 95% CI 0.32 to 1.25; P>0.05), or recurrence (OR 0.62; 95% CI 0.33 to 1.16; P>0.05).

Conclusions

LAG could be performed safely for AGC with adequate lymphadenectomy and has several short-term advantages compared with conventional OG. No differences were found in long-term outcomes. However, these results should be validated in large randomized controlled studies (RCTs) with sufficient follow-up.     

Economic evaluation research in the context of Child Welfare policy: a structured literature review and recommendations

Objectives

With over 1 million children served by the US Child Welfare system at a cost of $20 billion annually, this study examines the economic evaluation literature on interventions to improve outcomes for children at risk for and currently involved with the system, identifies areas where additional research is needed, and discusses the use of decision-analytic modeling to advance Child Welfare policy and practice.

Methods

The review included 19 repositories of peer-reviewed and non-peer-reviewed “gray” literatures, including items in English published before November, 2009. Original research articles were included if they evaluated interventions based on costs and outcomes. Review articles were included to assess the relevance of these techniques over time and to highlight the increasing discussion of methods needed to undertake such research. Items were categorized by their focus on: interventions for the US Child Welfare system; primary prevention of entry into the system; and use of models to make long-term projections of costs and outcomes.

Results

Searches identified 2,640 articles, with 49 ultimately included (19 reviews and 30 original research articles). Between 1988 and 2009, reviews consistently advocated economic evaluation and increasingly provided methodological guidance. 21 of the original research articles focused on Child Welfare, while 9 focused on child mental health. Of the 21 Child Welfare articles, 81% (17) focused on the US system. 47% (8/17) focused exclusively on primary prevention, though 83% of the US system, peer-reviewed articles focused exclusively on prevention (5/6). 9 of the 17 articles included empirical follow-up (mean sample size: 264 individuals; mean follow-up: 3.8 years). 10 of the 17 articles used modeling to project longer-term outcomes, but 80% of the articles using modeling were not peer-reviewed. Although 60% of modeling studies included interventions for children in the system, all peer-reviewed modeling articles focused on prevention.

Conclusions

Methodological guidance for economic evaluations in Child Welfare is increasingly available. Such analyses are feasible given the availability of nationally representative data on children involved with Child Welfare and evidence-based interventions.

Practice implications

Policy analyses considering the long-term costs and effects of interventions to improve Child Welfare outcomes are scarce, feasible, and urgently needed.     

A cross-cultural comparative study of teacher effectiveness: Analyses of award-winning teachers in the United States and China

The purpose of this study was to develop a richer understanding of teacher effectiveness through cross-cultural analyses of the practices and beliefs of selected China and US teachers who have received national awards for their teaching. This study was based upon a phenomenological design that used semi-structured interviews, classroom observations, and artifacts for data generation/collection. Sixteen China teachers and 16 US teachers participated in this study. This study revealed similarities and differences between US teachers and China teachers in their patterns of instructional practices and professional thinking. The major similarities found between them were (a) using a variety of instructional activities which spanned across different cognitive levels, (b) being opportunistic planners to maximize meaningful student learning, (c) having high student engagement, (d) presenting effective classroom management skills, and (e) maintaining a learning environment that was conducive to optimal learning. Primary differences between US and China teachers’ classrooms included the types of instructional activities used and their beliefs and practices in the areas of (a) instructional planning, (b) differentiation, (c) assessment, (d) classroom management, (e) relationships with students and parents, and (f) professional development.     

Cultural Dimensions of the Learning Environment in Brunei

The aim of this research was to study (a) trends in culturally sensitive factors (gender equity, collaboration, deference, competition, modeling, and congruence), of students in lower secondary (LS), upper secondary (US), and tertiary (TS) learning environments and (b) the gender differences in these trends. The study included 2,212 subjects (LS, 41.2%; US, 37.2%; TS, 21.5%; male, 39.3%; female, 60.7%) from Brunei. Data were collected by administering the Classroom Learning Environment Questionnaire (CLEQ) to the students. A steady increase in gender equity was observed from LS, through US to TS. The mean values on deference, modeling, and congruence scales were comparable for LS and US, whereas values decreased significantly for TS. It is also important to find ways to improve the magnitude of the factors in those educational institutions where students perceived low values.     

Universal,but not free: Household schooling costs and equity effects of Uganda’s Universal Secondary Education policy

A general consensus regarding universal schooling policies is that they have boosted enrollments while ignoring the quality of learning, although there is burgeoning research interest in the extent to which such policies have contributed to more equitable educational delivery. This paper analyzes household and school level effects of Uganda’s Universal Secondary Education (USE) policy, launched in 2007. We rely on data drawn from the Uganda National Panel Survey (UNPS) rounds in 2005 and 2009–11, which are included as part of the World Bank’s Living Standards Measurement Study (LSMS). We find that receipt of the USE capitation grant has increased substantially for most pupils, and is associated with a 60% reduction in household spending on education per child, at the lower secondary level. At the same time this relationship does not differ by wealth or by region. Further, we do not find evidence to suggest the policy boosted school attendance or retention, at the lower secondary level. Overall, our findings suggest a need for greater attention to the equity effects of universal education policies.     

The effect of US omission in classical aversive and appetitive conditioning of rabbits

Rabbits (Oryctolagus cuniculus) were given either a 100% or a 50% reinforcement schedule in classical conditioning. Two groups received an aversive US (shock) and two groups received an appetitive US (water to the oral cavity). With parameter estimates for the two-phase model serving as the dependent variables, it was possible to define more precisely the effect of US omission with the intermittent reinforcement schedule. For the aversive preparation, the major effect of intermittent reinforcement was to increase the duration of Phase 1, a phase during which response likelihood remains constant at its initial value. Only a small proportion of subjects reflected the effect of US omission during Phase 2, the “learning” phase, this being a low operator limit following trials on which neither the CR nor the US occurred. The major effect of US omission for the appetitive preparation was in Phase 2, primarily a result of a minority of subjects having a low operator limit following trials on which neither the CR nor the US occurred. Many subjects required separate operators for trials on which the CR did or did not occur. The results were interpreted to pose difficulties for strength theories of conditioning, and the limitation implied for successful application of the Rescorla-Wagner theory are discussed. The implications of the data for response-contingent interpretations and for individual differences are also discussed.