An interactive activation approach to object processing: effects of structural similarity, name frequency, and task in normality and pathology

We present a computational model of the processes involved in retrieving stored semantic and name information from objects, using a simple interactive activation and competition architecture. We simulate evidence showing a cross-over in normal reaction times to make semantic classification and identification responses to objects from categories with either structurally similar or structurally dissimilar exemplars, and that identification times to objects from these two different classes correlate differentially with measures of the structural similarity of objects within the category and the frequency of the object's name. Structural similarity exerts a negative effect on object decision as well as naming, though this effect is larger on naming. Also, on naming, structural similarity interacts with the effects of name frequency, captured in the model by varying the weight on connections from semantic to name units; frequency effects are larger with structurally dissimilar items. In addition, (1) the range of potential errors for objects from these two classes, when responses are elicited before activation reached a stable state, differ--a wider range of errors occur to objects from categories with structurally similar exemplars; and (2) simulated lesions to different locations within the model produce selective impairments to identification but not to semantic classification responses to objects from categories with structurally similar exemplars. We discuss the results in relation to data on visual object processing in both normality and pathology.     

Nitrogen-15 in apple nutrition investigations

Young apple trees growing in pots of soil were treated with N-15 labelled potassium nitrate or urea at different times of year. Over periods of several months whole trees were harvested and divided into their component tissues for total N and N-15 analyses; the latter were carried out using an emission spectrometer. Following treatments in mid-October 1972 and harvest in the following February, about 16% of N-15 from soil-applied nitrate and almost 47% of that from leafapplied urea was recovered in the trees. A later harvest in May 1973 showed that by then one-third to one-half of this fertiliser N had been translocated to the new leaves. Soil applications of nitrate were also made in March or August 1973 and the maximum recoveries of fertiliser N were about 40% and 60% respectively, much of which was in the leaves. In the fruit from the March-N trees, seeds and flesh were almost equally labelled but in that from the August-treated trees the seeds contained no excess N-15, although there was a considerable concentration in the flesh. Urea foliar sprays were also made in June or August 1973. The distributions of isotope were very similar following these treatments, in that the greater part remained in the leaves. The results are discussed in relation to previously published work on N in apple trees, with particular emphasis on the advantages in using N-15 to follow unambiguously the movement of N between the tissues of the tree.     

Categorizing chairs and naming pears: category differences in object processing as a function of task and priming

Four experiments are reported examining the locus of structural similarity effects in picture recognition and naming with normal subjects. Subjects carried out superordinate categorization and naming tasks with picture and word forms of clothing, furniture, fruit, and vegetable exemplars. The main findings were as follows: (1) Responses to pictures of fruit and vegetables ("structurally similar" objects) were slowed relative to pictures of clothing and furniture ("structurally dissimilar" objects). This structural similarity difference was greater for picture naming than for superordinate categorization of pictures. (2) Structural similarity effects in picture naming were reduced by repetition priming. Repetition priming effects were equivalent from picture and word naming as prime tasks. (3) However, superordinate categorization of the prime did not produce the structural similarity effects on priming found for picture naming. Furthermore, such priming effects did not arise for picture or word categorization or for reading picture names as target tasks. It is proposed that structural similarity effects on priming object processing are located in processes mapping semantic representations of pictures to name representations required to select names for objects. Visually based competition between fruit and vegetables produces competition in name selection, which is reduced by priming the mappings between semantic and name representations.     

Accuracy of death certificates for coding coronary heart disease as the cause of death

BACKGROUND: Death certificates are widely used in epidemiologic and clinical investigations and for national statistics. OBJECTIVE: To examine the accuracy of death certificates for coding coronary heart disease as the underlying cause of death. DESIGN: Community-based inception cohort followed since 1948. SETTING: Framingham, Massachusetts. PATIENTS: 2683 deceased Framingham Heart Study participants. MEASUREMENTS: Sensitivity, specificity, and predictive values of the death certificate. The reference standard was cause of death adjudicated by a panel of three physicians. RESULTS: Among 2683 decedents, the death certificate coded coronary heart disease as the underlying cause of death for 942; the physician panel assigned coronary heart disease for 758. The death certificate had a sensitivity of 83.8% (95% CI, 81.1 % to 86.4%), positive predictive value of 67.4% (CI, 64.4% to 70.4%), specificity of 84.1% (CI, 82.4% to 85.7%), and negative predictive value of 92.9% (CI, 91.7% to 94.1%) for coronary heart disease. The death certificate assigned coronary heart disease in 51.2% of 242 deaths (9.0% of total deaths) for which the physician panel could not determine a cause. Compared with the physician panel, the death certificate attributed 24.3% more deaths to coronary heart disease overall and more than twice as many deaths to coronary heart disease in decedents who were at least 85 years of age. When deaths that were assigned unknown cause by the physician panel were excluded, the death certificate still assigned more deaths to coronary heart disease (7.9% overall and 43.1% in the oldest age group). CONCLUSIONS: Coronary heart disease may be overrepresented as a cause of death on death certificates. National mortality statistics, which are based on death certificate data, may overestimate the frequency of coronary heart disease by 7.9% to 24.3% overall and by as much as two-fold in older persons.     

Convenient,Rapid and Highly Regioselective Cycloisomerisation of 4,4-Disubstituted Hepta-1,6-Dienes Employing Neutral Palladium Chloride pro-Catalysts

Optimum conditions for the cycloisomerisation of dimethyldiallylmalonate by complexes of the form [L₂PdCl₂] (L = RCN or DMSO) were found to be [(t-BuCN)₂PdCl₂] in 1,2-dichloroethane at 40°C. These conditions also allow the highly regioselective cycloisomerisation of a range of 4-substituted hepta-1,6-dienes to the corresponding 1-substituted 3,4-dimethylcyclopent-2-enes in good yield. However, substituents at the 4 position that are strongly coordinating inhibit the reaction.     

Distribution and identity of labelled products following autumn application of 15N-labelled urea or potassium nitrate fertilisers to apple trees

Young apple trees growing in pots of soil were treated in October with ¹⁵N-labelled urea on the foliage or with K¹⁵NO₃ via the soil. Whole trees were sampled in the following February and May and the tissues extracted to determine the concentrations of the major nitrogenous constituents and their ¹⁵N enrichments. At the February samplings following both treatments half the ¹⁵N was in the insoluble fraction, and the soluble part consisted almost entirely of arginine and asparagine. But the two treatments gave quite different distributions of ¹⁵N between the two amino acids Urea applied to the leaves resulted in over four times as much ¹⁵N in arginine as in asparagine; in contrast, from the soil nitrate treatment the distribution was almost equal. When sampled in May the new leaves and blossoms contained a large proportion of the total ¹⁵N in the tree. Comparison of these results with those from the February sampling leads to the conclusion that the nitrogen for this new growth had come from the insoluble N and arginine reserves and that the asparagine reserve had made little contribution to growth up to this time.     

The Slow-Release Strategy in Suzuki–Miyaura Coupling

Despite great advances in metal-catalyzed cross-coupling reactions, their efficacy is often compromised by side reactions, reducing the yield, or requiring a large excess of one component. Suzuki–Miyaura cross-coupling is no exception, as the boronic acid functionality can be susceptible to a range of undesired processes. A number of methods have been developed to mitigate these side reactions, and herein we focus on the “slow-release” strategy. These conditions involve deployment of a “masking” reagent that protects the vulnerable boronic acid functionality from degradation, particularly protodeboronation, whilst simultaneously facilitating controlled liberation of the active reagent into the catalytic milieu. Under suitably tailored conditions, this dual-action approach ensures that the concentration of the free boronic acid is minimized, thus attenuating its degradation but still facilitating transmetallation of the organoboron species with the key organopalladium intermediate.     

Semantic interference from visual object recognition on visual imagery.

A new technique for examining the interaction between visual object recognition and visual imagery is reported. The "image-picture interference" paradigm requires participants to generate and make a response to a mental image of a previously memorized object, while ignoring a simultaneously presented picture distractor. Responses in 2 imagery tasks (making left-right higher spatial judgments and making taller-wider judgments) were longer when the simultaneous picture distractor was categorically related to the target distractor relative to unrelated and neutral target-distractor combinations. In contrast, performance was not influenced in this way when the distractor was a related word, when a semantic categorization decision was made to the target, or when distractor and target were visually but not categorically related to one another. The authors discuss these findings in terms of the semantic representations shared by visual object recognition and visual imagery that mediate performance. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Elderly patients receive less aggressive medical and invasive management of unstable angina: potential impact of practice guidelines

BACKGROUND: The Agency for Health Care Policy and Research (AHCPR) released a practice guideline on the diagnosis and management of unstable angina in 1994. OBJECTIVE: To examine practice variation across the age spectrum in the management of patients hospitalized with unstable angina 2 years before release of the AHCPR guideline. DESIGN: Retrospective cohort. SETTING: Urban academic hospital. PATIENTS: All nonreferral patients diagnosed as having unstable angina who were hospitalized directly from the emergency department to the intensive care or telemetry unit between October 1, 1991, and September 30, 1992. MEASUREMENTS: Percentage of eligible patients receiving medical treatment concordant with 8 important AHCPR guideline recommendations. RESULTS: Half of the 280 patients were older than 66 years; women were older than men on average (70 vs 64 years; P<.001). After excluding those with contraindications to therapy, patients in the oldest quartile (age, 75.20-93.37 years) were less likely than younger patients to receive aspirin (P<.009), beta-blockers (P<.04), and referral for cardiac catheterization (P<.001). Overall guideline concordance weighted for the number of eligible patients declined with increasing age (87.4%, 87.4%, 84.0%, and 74.9% for age quartiles 1 to 4, respectively; chi2, P<.001). Increasing age, the presence of congestive heart failure at presentation, a history of congestive heart failure, previous myocardial infarction, increasing comorbidity, and elevated creatinine concentration were associated with care that was less concordant with AHCPR guideline recommendations; only age and congestive heart failure at presentation remained significant in the multivariate analysis (odds ratios, 1.28 per decade [95% confidence interval, 1.02-1.61] and 3.16 [95% confidence interval, 1.57-6.36], respectively). CONCLUSIONS: Older patients were less likely to receive standard therapies for unstable angina before release of the 1994 AHCPR guideline. Patients presenting with congestive heart failure also received care that was more discordant with guideline recommendations. The AHCPR guideline allows identification of patients who receive nonstandard care and, if applied to those patients with the greatest likelihood to benefit, could lead to improved health care delivery.