Showing papers by "University of Toronto published in 1988"
15 Jun 1988
TL;DR: In this article, simple state-space formulas are presented for a controller solving a standard H∞-problem, where the controller has the same state-dimension as the plant, its computation involves only two Riccati equations, and it has a separation structure reminiscent of classical LQG theory.
Abstract: Simple state-space formulas are presented for a controller solving a standard H∞-problem. The controller has the same state-dimension as the plant, its computation involves only two Riccati equations, and it has a separation structure reminiscent of classical LQG (i.e., H2) theory. This paper is also intended to be of tutorial value, so a standard H2-solution is developed in parallel.
2,875 citations
TL;DR: To overcome possible myopia, the evidence of advantage should illuminate the sources of advantage as well as the manifestations of superior customer value and cost superiority, and should be based on a balance of customer and competitor perspectives.
Abstract: Strategy is about seeking new edges in a market while slowing the erosion of present advantages. Effective strategy moves are grounded in valid and insightful monitoring of the current competitive ...
2,744 citations
TL;DR: The observations show that bone-like tissue can be synthesized in vitro by cells cultured from young-adult bone marrow, provided that the medium contains both β-glycerophosphate and, particularly, dexamethasone.
Abstract: Cells from fetal or neonatal skeleton can synthesize bone-like tissue in vitro In contrast, formation of bone-like tissue in vitro by cells derived from adult animals has rarely been reported and has not been achieved using cells from bone marrow We have explored development of bone-like tissue in vitro by bone marrow stromal cells Marrow stromal cells obtained from 40-43-day-old Wistar rats were grown in primary culture for 7 days and then subcultured for 20-30 days Cells were cultured in either alpha-minimal essential medium containing 15% fetal bovine serum, antibiotics, and 50 micrograms/ml ascorbic acid, or the above medium supplemented with either 10 mM Na-beta-glycerophosphate, 10(-8) M dexamethasone, or a combination of both Cultures were examined using phase-contrast microscopy, undemineralized and demineralized tissue histology, histochemistry (for alkaline phosphatase activity), immunohistochemistry (for collagen type, osteonectin, and bone Gla-protein), scanning and transmission electron microscopy, energy dispersive X-ray microanalysis, and X-ray diffraction Collagenous, mineralized nodules exhibiting morphological and ultrastructural characteristics similar to bone were formed in the cultures, but only in the presence of both beta-glycerophosphate and dexamethasone Cells associated with the nodules exhibited alkaline phosphatase activity The matrix of the nodules was composed predominantly of type-I collagen and both osteonectin and Gla-protein were present X-ray microanalysis showed the presence of Ca and P, and X-ray diffraction indicated the mineral to be hydroxyapatite The nodules were also examined for bone morphogenetic protein-like activity Paired diffusion chambers containing partly demineralized nodules and fetal muscle were implanted intraperitonealy in rats Induction of cartilage in relation to muscle was observed histologically after 40 days in the chambers This finding provided further support for the bone-like nature of the nodules The observations show that bone-like tissue can be synthesized in vitro by cells cultured from young-adult bone marrow, provided that the medium contains both beta-glycerophosphate and, particularly, dexamethasone
1,317 citations
TL;DR: In this article, a power flow method is described for solving weakly meshed distribution and transmission networks, using a multiport compensation technique and basic formations of Kirchoff's laws.
Abstract: A power flow method is described for solving weakly meshed distribution and transmission networks, using a multiport compensation technique and basic formations of Kirchoff's laws. This method has excellent convergence characteristics and is robust. A computer program implementing this scheme was developed and successfully applied to several practical distribution and transmission networks with radial and weakly meshed structures. The method can be applied to the solution of both the three-phase (unbalanced) and single-phase (balanced) representation of the network, however, only the single-phase representation is treated in detail. >
1,108 citations
TL;DR: In this article, the development of children's understanding of representational change and its relation to other cognitive developments was investigated. But, the results showed that children begin to consider alternative representations of the same object at about age 4.
Abstract: This research concerns the development of children's understanding of representational change and its relation to other cognitive developments. Children were shown deceptive objects, and the true nature of the objects was then revealed. Children were then asked what they thought the object was when they first saw it, testing their understanding of representational change; what another child would think the object was, testing their understanding of false belief; and what the object looked like and really was, testing their understanding of the appearance-reality distinction. Most 3-year-olds answered the representational change question incorrectly. Most 5-year-olds did not make this error. Children's performance on the representational change question was poorer than their performance on the false-belief question. There were correlations between performance on all 3 tasks. Apparently children begin to be able to consider alternative representations of the same object at about age 4.
1,082 citations
TL;DR: Any pseudorandom bit generator can be used to construct a block private key cryptos system which is secure against chosen plaintext attack, which is one of the strongest known attacks against a cryptosystem.
Abstract: We show how to efficiently construct a pseudorandom invertible permutation generator from a pseudorandom function generator. Goldreich, Goldwasser and Micali [“How to construct random functions,” P...
1,075 citations
TL;DR: The deduced amino acid sequence of AR within the DNA-binding domain has highest sequence identity with the progesterone receptor.
Abstract: The androgen receptor (AR) mediates the actions of male sex steroids. Human AR genomic DNA was cloned from a flow-sorted human X chromosome library by using a consensus nucleotide sequence from the DNA-binding domain of the family of nuclear receptors. The AR gene was localized on the human X chromosome between the centromere and q13. Cloned complementary DNA, selected with an AR-specific oligonucleotide probe, was expressed in monkey kidney (COS) cells and yielded a high-affinity androgen-binding protein with steroid-binding specificity corresponding to that of native AR. A predominant messenger RNA species of 9.6 kilobases was identified in human, rat, and mouse tissues known to contain AR and was undetectable in tissues lacking AR androgen-binding activity, including kidney and liver from androgen-insensitive mice. The deduced amino acid sequence of AR within the DNA-binding domain has highest sequence identity with the progesterone receptor.
976 citations
TL;DR: The author discusses the prevalence, clinical manifestations, etiology, and treatment of somatization, and presents a critical review of somatoform disorders.
Abstract: Somatization, a tendency to experience and communicate somatic distress in response to psychosocial stress and to seek medical help for it, poses a major medical, social, and economic problem. It is most often associated with depressive and anxiety disorders and constitutes the core of somatoform disorders. Its persistent form is especially costly and difficult to prevent and manage. The author discusses the prevalence, clinical manifestations, etiology, and treatment of somatization and presents a critical review of somatoform disorders.
967 citations
01 Jan 1988
TL;DR: Structural (or network) analysis has mystified many social scientists as mentioned in this paper, who have rejected it as mere methodology, which lacks due regard for substantive issues, and fled from its unusual terms and techniques, not having played with blocks and graphs since grammar school.
Abstract: Structural (or network) analysis has mystified many social scientists. Some have rejected it as mere methodology, which lacks due regard for substantive issues. Some have fled from its unusual terms and techniques, not having played with blocks and graphs since grammar school. Some have dismissed one portion for the whole, saying, for example, that their study of class structure has little need for the focus on friendship ties emphasized in network analysis. And some have scorned it as nothing new, claiming that they also study "social structure." Others have bolted on variables such as network "density" as they would a turbocharger in order to boost explained variance. Still others, attracted by the capability of studying nonhierarchical, nongroup structures, have expanded structural analysis into a network ideology that advocates egalitarian, open communities. Some have even used "network" as a verb and "networking" as a noun to advocate the deliberate creation and use of social networks for such desired ends as getting jobs or integrating communities. These misconceptions have arisen because too many analysts and
940 citations
TL;DR: A comprehensive account of the macroscopic and microscopic physical properties of chromium (and where appropriate those of its dilute alloys) that relate to its antiferromagnetism is given in this paper.
Abstract: A comprehensive account is given of the macroscopic and microscopic physical properties of chromium (and where appropriate those of its dilute alloys) that relate to its antiferromagnetism. Neutron scattering is treated in great detail, first in the historical introduction, then as an experimental probe of both the magnetic structure and the excitations of the incommensurate spin-density-wave state and (with the assistance of x rays) of the concomitant charge-density wave and strain wave. Neutron scattering is considered as a tool to explore not only the disappearance of long-range order with increasing temperature through the growth of excitations as the weak first-order N\'eel transition is approached, but also the persistence of these spin fluctuations well into the paramagnetic state---processes that are still little understood. The article surveys, without mathematical details, model systems designed to reproduce the magnetic and thermodynamic properties of Cr. The energy-band structure calculations are given a more comprehensive review. Special attention is paid to calculations of the wave-vector-dependent susceptibility that reproduce the observed wave vector of the spin-density wave, and to a recent finite-temperature calculation that gives almost the right N\'eel temperature. The review of Fermi-surface studies emphasizes those designed to relate the spin-density wave vector (and its pressure dependence) to the nesting vector of the Fermi surface. An account is given of the spectroscopic determination of the energy gap(s), whose theoretical analysis is still unclear, and of experiments aimed at determining physical properties that throw light on the origin of the weak first-order N\'eel transition. The article describes the use of magnetic anomalies in the elastic moduli to determine the volume dependence of the exchange interaction responsible for antiferromagnetism in Cr. The experimental features of the spin-flip transition are reviewed, although a theory of this phenomenon is wanting. The experimental study of microscopic structure by the use of hyperfine-interaction properties is surveyed. An account is given of both experimental and theoretical studies of the surface of Cr and of Cr films and sandwiches. Finally, "technical antiferromagnetism" is discussed: the effect of severe internal strain in producing a commensurate antiferromagnetic state, wave-vector Q domains, polarization S domains (for which the experimental evidence is scanty), and ultrasonic attenuation as a tool to study them.
866 citations
01 Apr 1988
TL;DR: The observability of discrete-event systems is investigated and a solution of the supervisory control and observation problem (SCOP) is obtained.
Abstract: The observability of discrete-event systems is investigated. A discrete-event system G is modeled as the controlled generator of a formal language L m ( G ) in the framework of Ramadge and Wonham. To control G, a supervisor S is developed whose action is to enable and disable the controllable events of G according to a record of occurrences of the observable events of G, in such a way that the resulting closed-loop system obeys some prespecified operating rules embodied in a given language K. A necessary and sufficient condition is found for the existence of a supervisor S such that L m ( S/G ) = K . Based on this condition, a solution of the supervisory control and observation problem (SCOP) is obtained. Two examples are provided.
TL;DR: This paper finds that the pivot algorithm is extraordinarily efficient: one “effectively independent” sample can be produced in a computer time of orderN, and presents a rigorous proof of ergodicity and numerical results on self-avoiding walks in two and three dimensions.
Abstract: The pivot algorithm is a dynamic Monte Carlo algorithm, first invented by Lal, which generates self-avoiding walks (SAWs) in a canonical (fixed-N) ensemble with free endpoints (hereN is the number of steps in the walk). We find that the pivot algorithm is extraordinarily efficient: one “effectively independent” sample can be produced in a computer time of orderN. This paper is a comprehensive study of the pivot algorithm, including: a heuristic and numerical analysis of the acceptance fraction and autocorrelation time; an exact analysis of the pivot algorithm for ordinary random walk; a discussion of data structures and computational complexity; a rigorous proof of ergodicity; and numerical results on self-avoiding walks in two and three dimensions. Our estimates for critical exponents areυ=0.7496±0.0007 ind=2 andυ= 0.592±0.003 ind=3 (95% confidence limits), based on SAWs of lengths 200⩽N⩽10000 and 200⩽N⩽ 3000, respectively.
TL;DR: In this article, the Tarski-Seidenberg theorem and Thorn's lemma are shown to be true for semianalytic sets, and the metric properties of subanalytic sets are investigated.
Abstract: 0. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 I. The Tarski-Seidenberg theorem and Thorn's lemma . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 2. Semianalytic sets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 3. Subanalytic sets 16 4. Transforming an analytic function to normal crossings by blowings-up 21 5. Uniformization and rcctilincarization 30 6. I.ojasicwicz's inequality; metric properties of subanalytic sets 33 7. Smooth points of a subanalytic sct 37 Bibliography 42
TL;DR: Since the TL method has now been shown to have fairly good reliability for assessing recent drinking across a broad range of drinkers, it can be used for comparative evaluations of drinking behaviour across studies with different subject populations.
Abstract: Summary
Since alcohol research involves both clinical and non-clinical populations, it is important to evaluate drinking assessment methods across different subject populations. Over the past several years, the reliability of the timeline (TL) method of gathering retrospective reports of recent drinking has been evaluated in several studies, and this method has been shown to have generally high reliability with outpatient alcohol abusers, in-patient chronic alcoholics, and normal drinker college students. The present study examined the reliability of the TL method with normal drinkers in the general population. Similar to other populations, the test-retest reliability of male (n=31) and female (n=31) normal drinkers' reports of recent drinking behaviour was found to be generally high. Data gathered by the TL method were also compared to data gathered from the same subjects using a common quantity-frequency (QF) method. Consistent with earlier reports, QF categorization provided a relatively insensitive measure of individual differences in drinking behaviour as compared to TL-derived data. Since the TL method has now been shown to have fairly good reliability for assessing recent drinking across a broad range of drinkers, it can be used for comparative evaluations of drinking behaviour across studies with different subject populations.
TL;DR: The data suggest that this clonal cell line contains subpopulations of mesenchymal progenitor cells which can, under the influence of glucocorticoid hormones, differentiate in vitro into four distinct cell types.
Abstract: RCJ 3.1, a clonally derived cell population isolated from 21-d fetal rat calvaria, expresses the osteoblast-associated characteristics of polygonal morphology, a cAMP response to parathyroid hormone, synthesis of predominantly type I collagen, and the presence of 1,25-dihydroxyvitamin D3-regulated alkaline phosphatase activity. When cultured in the presence of ascorbic acid, sodium beta-glycerophosphate, and the synthetic glucocorticoid dexamethasone, this clone differentiated in a time-dependent manner into four morphologically distinct phenotypes of known mesenchymal origin. Multinucleated muscle cells were observed as early as 9-10 d in culture, lipid-containing adipocytes formed after 12 d, chondrocyte nodules were observed after 16 d, and mineralized bone nodules formed after 21 d in culture. The differentiated cell types were characterized morphologically, histochemically, and immunohistochemically. The formation of adipocytes and chondrocytes was dependent upon the addition of dexamethasone; the muscle and bone phenotypes were also expressed at low frequency in the absence of dexamethasone. The sex steroid hormones progesterone and 17 beta-estradiol had no effect on differentiation in this system, suggesting that the effects of dexamethasone represent effects specific for glucocorticosteroids. Increasing concentrations of dexamethasone (10(-9)-10(-6) M) increased the numbers of myotubes, adipocytes, and chondrocytes; however, when present continuously for 35 d, the lower concentrations appeared to better maintain the muscle and adipocyte phenotypes. Bone nodules were not quantitated because the frequency of bone nodule formation was too low. Single cells obtained by plating RCJ 3.1 cells at limiting dilutions in the presence of dexamethasone, were shown to give rise to subclones that could differentiate into either single or multiple phenotypes. Thus, the data suggest that this clonal cell line contains subpopulations of mesenchymal progenitor cells which can, under the influence of glucocorticoid hormones, differentiate in vitro into four distinct cell types. It is, therefore, a unique cell line which will be of great use in the study of the regulation of mesenchymal stem cell differentiation.
TL;DR: Differences in growth and survival in these two patient groups, with very similar age-specific pulmonary function, suggest further examination of nutritional guidance and intervention in CF, especially regarding the traditional restriction of dietary fat.
TL;DR: It is shown that anti-bodies directed against synthetic peptides and fusion proteins derived from the N-terminal region of human DMD cDNA strongly react with an antigen present in skeletal muscle sar-colemma on cryostat sections of normal human muscle biopsies and concludes that the product of the DMD gene is associated with the sar colemma rather than with the triads.
Abstract: Duchenne muscular dystrophy (DMD) and its milder form, Becker muscular dystrophy (BMD), are allelic X-linked muscle disorders in man. The gene responsible for the disease has been cloned from knowledge of its map location at band Xp21 on the short arm of the X chromosome. The product of the DMD gene, a protein of relative molecular mass 400,000 (Mr 400K) recently named dystrophin, has been reported to co-purify with triads of mouse and rabbit skeletal muscle when assayed using polyclonal antibodies raised against fusion proteins encoded by regions of mouse DMD complementary DNA. Here we show that antibodies directed against synthetic peptides and fusion proteins derived from the N-terminal region of human DMD cDNA strongly react with an antigen present in skeletal muscle sarcolemma on cryostat sections of normal human muscle biopsies. This immunoreactivity is reduced or absent in muscle fibres from DMD patients but appears normal in muscle fibres from patients with other myopathic diseases. The same antibodies specifically react with a 400K protein in sodium dodecyl sulphate (SDS) extracts of normal human muscle subjected to Western blot analysis. We conclude that the product of the DMD gene is associated with the sarcolemma rather than with the triads and speculate that it strengthens the sarcolemma by anchoring elements of the internal cytoskeleton to the surface membrane.
TL;DR: The distribution of diadromous species is examined with respect to global patterns in aquatic productivity, and the contrasting directions of migration can be explained by the relative availability of food resources in ocean and freshwater habitats.
Abstract: Diadromous migration, in which some fish species migrate from freshwater and feed in the ocean (anadromous species) and others migrate from the ocean and feed in freshwater (catadromous), has long been perplexing However, when the distribution of diadromous species is examined with respect to global patterns in aquatic productivity, this apparent paradox is resolved The contrasting directions of migration can largely be explained by the relative availability of food resources in ocean and freshwater habitats Oceans are more productive than freshwaters in temperate latitudes, and anadromous species predominate In contrast, catadromous species generally occur in tropical latitudes where freshwater productivity exceeds that of the ocean
TL;DR: The results indicated that, depending on the neuropathologic criteria applied, the clinicopathologic agreement ranged from 64% to 86%.
Abstract: Neuropathologic confirmation is required to validate the NINCDS-ADRDA Work Group criteria for the clinical diagnosis of Alzheimer's disease (AD). Neuropathologic inclusion and exclusion criteria for AD, however, are not uniform. The purpose of this investigation was to examine the confirmation rate for the Work Group criteria against differing neuropathologic criteria for AD. The sample consisted of 57 cases, 22 of which had received a clinical diagnosis of AD. Nine neuropathologic criteria for AD were applied in a blind fashion to each of the 57 cases. Our results indicated that, depending on the neuropathologic criteria applied, the clinicopathologic agreement ranged from 64% to 86%. These findings demonstrate the need for universally accepted neuropathologic and clinical criteria for AD.
TL;DR: An autogenous graft of tibial periosteum was sutured to the base of a five by ten-millimeter full-thickness defect in the patellar groove of each of forty-five adolescent rabbits to analyzed macroscopically, histologically, histochemically, and biochemically one year postoperatively.
Abstract: An autogenous graft of tibial periosteum was sutured (with its cambium layer facing into the joint) to the base of a five by ten-millimeter full-thickness defect in the patellar groove of each of forty-five adolescent rabbits. The rabbits were randomly treated postoperatively by either four weeks of immobilization in a cast, intermittent active motion in a cage, or two weeks of continuous passive motion. One year postoperatively, the regenerated tissue from each rabbit was analyzed macroscopically, histologically, histochemically, and biochemically. Gross degenerative changes were seen in 57 per cent of the rabbits that had been immobilized in a cast, in 73 per cent of the rabbits that had been allowed intermittent active motion, and in 22 per cent of the rabbits that had been subjected to continuous passive motion (p less than 0.05). Out of a possible score of 7.0 points for the nature of the regenerated tissue, the scores for the three groups were: immobilization in a cast, 4.1 points; intermittent active motion, 4.0 points; and continuous passive motion, 5.9 points (p greater than 0.05). Out of a possible perfect combined score of 10.0 points for the structural characteristics of the regenerated tissue, the cast-immobilization group scored 3.8 points; the intermittent active-motion group, 2.5 points; and the continuous passive-motion group, 6.4 points (p less than 0.001). The total scores for freedom from cellular changes of degeneration, a perfect score being 5.0 points, were: immobilization in a cast, 2.4 points; intermittent active motion, 2.3 points; and continuous passive motion, 3.9 points (p less than 0.01). Degenerative changes in the adjacent cartilage, which were noted in 42 and 46 per cent of the knees in the immobilization and intermittent active-motion groups, respectively, were not found in the knees that had been subjected to continuous passive motion (p less than 0.05). The total indices, which were derived by combining the scores for all categories (maximum, 24.0 points), revealed that the index for the continuous passive-motion group was significantly better than the index for either of the other two groups: immobilization in a cast, 12.9 points; intermittent active motion, 11.2 points; and continuous passive motion, 19.2 points (p less than 0.0005).(ABSTRACT TRUNCATED AT 400 WORDS)
TL;DR: 3 lines of evidence indicate that myelinated primary afferents, perhaps A&bgr; fibers, signal the hyperalgesic pain in causalgia, which may be sensitized A&Bgr; nociceptors or low‐threshold mechanoreceptors.
Abstract: Pain to light touching of the skin is a hallmark sign of causalgia. The purpose of this study was to determine whether myelinated or unmyelinated afferent fibers signal this hyperalgesia. Sensory testing was performed in 17 patients with long-standing hyperalgesia after nerve injury. The patients underwent a differential ischemic block of nerve function of the involved area. At a time when touch sensation in adjacent normal skin was eliminated, but when sensibility to warming and cooling stimuli was unaffected, the hyperalgesia to mechanical stimuli was abolished in 15 of the subjects. In 2 of these 15 patients, a differential local anesthetic block of the injured nerve was performed proximal to the site of injury. When temperature sensibility was absent, but when touch sensation was intact, hyperalgesia was present. In a third study, latency measurements in response to 400 micron stepped displacement stimuli were made in two patients who had hyperalgesia on the foot. The mean latency for detection of pain in the hyperalgesic region was 414 +/- 18 msec, compared to 458 +/- 16 msec for the detection of touch to the same stimuli applied to the opposite normal foot. These 3 lines of evidence indicate that myelinated primary afferents, perhaps A beta fibers, signal the hyperalgesic pain in causalgia. These fibers may be sensitized A beta nociceptors or low-threshold mechanoreceptors.
TL;DR: Ben Zeev et al. as mentioned in this paper presented a framework for relating degree of bilingualism to aspects of linguistic awareness, in which metalinguistic tasks are described in terms of their demands for analysis of knowledge or control of processing.
Abstract: A framework for relating degree of bilingualism to aspects of linguistic awareness is presented in which metalinguistic tasks are described in terms of their demands for analysis of knowledge or control of processing. Two studies are reported in which children differing in their level of bilingualism were given metalinguistic problems to solve that made demands on either analysis or control. The hypotheses were that all bilingual children would perform better than monolingual children on all metalinguistic tasks requiring high levels of control of processing and that fully bilingual children would perform better than partially bilingual children on tasks requiring high levels of analysis of knowledge. The results were largely consistent with these predictions. The findings are discussed in terms of the implications of bilingualism for cognitive and linguistic development. Research investigating the effects of bilingualism on a variety of academic, linguistic, and intellectual achievements has traditionally led to conflicting results. Many of the early studies that warned of disastrous effects of bilingualism on cognitive development (see Darcy, 1963, for review) were later found to lack proper controls, undermining any interpretation of those findings. Later work revealed a more promising intellectual prognosis for bilingual children. Peal and Lambert (1962), for example, showed how careful selection of subjects in the bilingual population could produce evidence of bilingual superiority on some intelligence tests. The relation between bilingualism and intelligence depended on factors such as social class, degree of language proficiency, and type of bilingualism (Cummins, 1976). A similar debate surrounds the examination of the relation between bilingualism and linguistic awareness. Evidence for a facilitating effect (Ben Zeev, 1977; Cummins, 1978;Ianco-Worrall, 1972), an inhibiting effect (Palmer, 1972), and no effect (Rosenblum & Pinker, 1983) of bilingualism have been reported. Some investigators have found effects in both directions when studying different samples of bilingual children (Ben Zeev, 1977; Cummins, 1978). Just as the early research on the intellectual effects of bilingualism failed to account for relevant factors, so too this problem requires consideration of a wider range of issues. To reconcile the diverse findings a more detailed examination of the two factors, bilingualism and linguistic awareness, is required. The claim proposed in this study is that the relation between bilingualism and linguistic awareness must be stated in terms of the degree and type of bilingualism as well as the degree and type of linguistic awareness.
TL;DR: Patients with early stage Parkinson's disease are shown to be selectively impaired in a cognitive task of procedural learning while remaining intact in recall and recognition tests of declarative memory, thus demonstrating a double dissociation.
Abstract: Patients with early stage Parkinson's disease are shown to be selectively impaired in a cognitive task of procedural learning while remaining intact in recall and recognition tests of declarative memory. In contrast, amnestic patients showed the opposite set of deficits, thus demonstrating a double dissociation. Patients with early Huntington's disease were either comparable to the parkinsonian patients or to amnesties. In the advanced Huntington's group, both procedural learning and declarative memory were impaired. It is argued that cognitive procedural learning depends on the establishment of heuristic strategies through the action of a circuit which involves the neostriatum and the prefrontal cortex.
TL;DR: In the present analysis, estimates of completeness of the registry as a whole were remarkably similar using either two or three data sources, and site-specific comparisons differed by at most 7%.
TL;DR: The evidence demonstrates the existence of a continuum of body plan phenotypes based on this premise, which suggests that lithium respecifies the mesoderm of Xenopus laevis embryos so that it differentiates into the Spemann organizer.
TL;DR: Rennie et al. as mentioned in this paper discussed the challenges and limitations of grounded theory in psychotherapy process research and illustrated the application of grounded approach in terms of its application to psychotherapy processes.
Abstract: There is a growing body of opinion that psychology suffers from an elaborate research technology that overemphasizes theory verification and impairs thinking and discovery. Grounded theory is advanced as an approach to research that can address this crisis of method in psychology. The grounded approach is described and illustrated in terms of its application to psychotherapy process research. The emphasis on theory creation characterizing the approach is examined within the history of induction. The challenges to and limitations of grounded theory are discussed. There are growing indications that psychology as a discipline is undergoing a crisis of confidence about its research methods. These rumblings of discontent were felt two decades ago when Bakan (1967) characterized psychologists as playing at science in much the way children play at being cowboys, imitating every aspect of cowboy life except the one which is most central — taking care of cows. In much the same way, Bakan contended, psychologists have been concerned with developing an elaborate research technology while ignoring the main work of science — thinking and discovery. The fault does not lie entirely with contemporary psychologists. It has been pointed out that psychology imitated physics with its emphasis on hypothetico-deductive research while in retrospect the fledgling science might have found astronomy or zoology, with their emphasis on Research leading to this paper was supported by Social Sciences and Humanities Research Council of Canada Grants 451-83-3642 and 410-83-1264 to David Rennie. We gratefully acknowledge the assistance of D. Bakan, G. Cupchik, K. Danziger, R. Goranson, L. Heshusius, R. Kroger, A. Mahrer, J. Martin, S. Mor, A. Shaul, I. Silverman, J. Weiser, M. Westcott, and L. Wood who commented on earlier drafts of the paper. Reprint requests may be sent to David L. Rennie, Department of Psychology, York University, North York, Ontario, M3J 1P3. description, more appropriate models (Endler, 1984; Kendler, 1986). As a result, the ensuing technology has increasingly dictated the kinds of studies that are done and has made theorizing less common and less respectable than energetic but trivial research (Bakan, 1967; Brandt, 1982; Endler, 1984; Gergen, 1982; Koch, 1981; Secord, 1982; Silverman, 1977). Many theories that have been developed have been tested by disjointed investigations of irrelevant hypotheses (Arthur, 1983). Even when the hypotheses of studies have been more closely tied to theories, testing has been contaminated by research participants responding to their own inner hypotheses about the experiments in which they are engaged (Orne, 1962; Silverman, 1977). Furthermore, speculation that investigators themselves are incapable of shedding biases despite the most rigorous experimental approaches (Kuhn, 1970; Polanyi, 1969) has received empirical support
TL;DR: The results indicate that the combination of 5-FU and FA is effective treatment for patients with metastatic or recurrent carcinoma of the rectum and colon who have not received prior chemotherapy.
Abstract: We determined the therapeutic effect of fluorouracil (5-FU) in combination with folinic acid (FA) in patients with measurable recurrent or metastatic carcinoma of the colon or rectum by comparing it to standard 5-FU therapy in a prospective randomized controlled trial. Patients were randomized to receive either FA, 200 mg/m2/d for five consecutive days, or nothing. All patients received 5-FU, 370 mg/m2/d for five days on the first course, with subsequent dose modifications to maintain equal toxicity in the two arms. One hundred thirty patients were entered on trial and only five were excluded from the analysis because they did not meet the eligibility criteria or they refused therapy after randomization. The two treatment arms were balanced for 11 clinical characteristics. Patients were evaluated for response at the end of every two treatment courses and toxicity after every course of therapy. Median follow-up was 1.45 years. Dose-limiting toxicity was mucositis and diarrhea on this treatment schedule, although neutropenia was apparent. The response rate was 33% (21 of 63 patients) in the 5-FU and FA arm and was 7% (four of 61 patients) in the 5-FU arm (P less than .0005). Time to disease progression was significantly different in the combination arm as compared with the single-agent arm (P = .023). Overall survival was significantly longer for patients treated with 5-FU and FA as compared with those receiving 5-FU alone (P = .05). The median survival was 12.6 months for patients receiving the combination, and 9.6 months for those receiving 5-FU alone. Our results indicate that the combination of 5-FU and FA is effective treatment for patients with metastatic or recurrent carcinoma of the rectum and colon who have not received prior chemotherapy.
TL;DR: In this article, the time-resolved optical Kerr responses of several simple molecular liquids are probed with 65-fs laser pulses and four dynamically distinct responses associated with the nonlinear susceptibility are observed in every liquid that possesses a permanent anisotropic polarizability.
Abstract: The time-resolved optical Kerr responses of several simple molecular liquids are probed with 65-fs laser pulses. Four dynamically distinct responses associated with the nonlinear susceptibility are observed in every liquid that possesses a permanent anisotropic polarizability. A simple model that specifically includes inertial effects provides an excellent description of the entire temporal profile of the Kerr signal of each liquid investigated. The role of coherent-coupling effects in the interpretation of optical Kerr data is outlined both experimentally and theoretically. >
TL;DR: A system in which immune-deficient mice are repopulated with cells from the human myeloid lineage, and that provides an in vivo stem cell assay for human hematopoietic cells is described, laying the foundation for establishing animal models for a wide variety of human hemopathies.
Abstract: A system in which immune-deficient mice are repopulated with cells from the human myeloid lineage, and that provides an in vivo stem cell assay for human hematopoietic cells is described. Generation of the chimeric human/immune-deficient (HID) mice was dependent on the use of immune-deficient bg/nu/xid mice. Infusion of these mice with human bone marrow gave rise to increases in human macrophage progenitors during more than 5 weeks of in vivo growth, indicating the seeding, proliferation, and differentiation of human stem cells. The human identity of the progenitors was confirmed by sequence analysis and their dependence on human growth factors. The creation of HID mice lays the foundation for establishing animal models for a wide variety of human hemopathies, from leukemia to infectious disease.