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Showing papers by "Harvard University published in 1985"


Journal ArticleDOI
TL;DR: This article used multivariate matching methods in an observational study of the effects of prenatal exposure to barbiturates on subsequent psychological development, using the propensity score as a distinct matching variable.
Abstract: Matched sampling is a method for selecting units from a large reservoir of potential controls to produce a control group of modest size that is similar to a treated group with respect to the distribution of observed covariates. We illustrate the use of multivariate matching methods in an observational study of the effects of prenatal exposure to barbiturates on subsequent psychological development. A key idea is the use of the propensity score as a distinct matching variable.

5,633 citations


Journal ArticleDOI
TL;DR: Data indicate that a simple self-administered dietary questionnaire can provide useful information about individual nutrient intakes over a one-year period.
Abstract: The aim of this study was to evaluate the reproducibility and validity of a 61-item semiquantitative food frequency questionnaire used in a large prospective study among women. This form was administered twice to 173 participants at an interval of approximately one year (1980-1981), and four one-week diet records for each subject were collected during that period. Intraclass correlation coefficients for nutrient intakes estimated by the one-week diet records (range = 0.41 for total vitamin A without supplements to 0.79 for vitamin B6 with supplements) were similar to those computed from the questionnaire (range = 0.49 for total vitamin A without supplements to 0.71 for sucrose), indicating that these methods were generally comparable with respect to reproducibility. With the exception of sucrose and total carbohydrate, nutrient intakes from the diet records tended to correlate more strongly with those computed from the questionnaire after adjustment for total caloric intake. Correlation coefficients between the mean calorie-adjusted intakes from the four one-week diet records and those from the questionnaire completed after the diet records ranged from 0.36 for vitamin A without supplements to 0.75 for vitamin C with supplements. Overall, 48% of subjects in the lowest quintile of calorie-adjusted intake computed from the diet records were also in the lowest questionnaire quintile, and 74% were in the lowest one of two questionnaire quintiles. Similarly, 49% of those in the highest diet record quintile were also in the highest questionnaire quintile, and 77% were in the highest one or two questionnaire quintiles. These data indicate that a simple self-administered dietary questionnaire can provide useful information about individual nutrient intakes over a one-year period.

4,012 citations


Journal ArticleDOI
John Daugman1
TL;DR: Evidence is presented that the 2D receptive-field profiles of simple cells in mammalian visual cortex are well described by members of this optimal 2D filter family, and thus such visual neurons could be said to optimize the general uncertainty relations for joint 2D-spatial-2D-spectral information resolution.
Abstract: Two-dimensional spatial linear filters are constrained by general uncertainty relations that limit their attainable information resolution for orientation, spatial frequency, and two-dimensional (2D) spatial position. The theoretical lower limit for the joint entropy, or uncertainty, of these variables is achieved by an optimal 2D filter family whose spatial weighting functions are generated by exponentiated bivariate second-order polynomials with complex coefficients, the elliptic generalization of the one-dimensional elementary functions proposed in Gabor’s famous theory of communication [ J. Inst. Electr. Eng.93, 429 ( 1946)]. The set includes filters with various orientation bandwidths, spatial-frequency bandwidths, and spatial dimensions, favoring the extraction of various kinds of information from an image. Each such filter occupies an irreducible quantal volume (corresponding to an independent datum) in a four-dimensional information hyperspace whose axes are interpretable as 2D visual space, orientation, and spatial frequency, and thus such a filter set could subserve an optimally efficient sampling of these variables. Evidence is presented that the 2D receptive-field profiles of simple cells in mammalian visual cortex are well described by members of this optimal 2D filter family, and thus such visual neurons could be said to optimize the general uncertainty relations for joint 2D-spatial–2D-spectral information resolution. The variety of their receptive-field dimensions and orientation and spatial-frequency bandwidths, and the correlations among these, reveal several underlying constraints, particularly in width/length aspect ratio and principal axis organization, suggesting a polar division of labor in occupying the quantal volumes of information hyperspace. Such an ensemble of 2D neural receptive fields in visual cortex could locally embed coarse polar mappings of the orientation–frequency plane piecewise within the global retinotopic mapping of visual space, thus efficiently representing 2D spatial visual information by localized 2D spectral signatures.

3,392 citations


Journal ArticleDOI
TL;DR: These studies indicate that analyses of the caudate nucleus in grade 4 would reflect mainly its astrocytic composition with a component of remote neurons projecting to the striatum, which would reflect early cellular and biochemical changes in HD.
Abstract: In postmortem brain specimens from 163 clinically diagnosed cases of Huntington's disease (HD) the striatum exhibited marked variation in the severity of neuropathological involvement. A system for grading this severity was established by macroscopic and microscopic criteria, resulting in five grades (0-4) designated in ascending order of severity. The grade correlates closely with the extent of clinical disability as assessed by a rating scale. In five cases of clinically diagnosed HD there were no discernible neuropathological abnormalities (grade 0), suggesting that the anatomical changes lag behind the development of clinical abnormalities. In eight cases, neuropathological changes could only be recognized microscopically (grade 1). The earliest changes were seen in the medial paraventricular portions of the caudate nucleus (CN), in the tail of the CN, and in the dorsal part of the putamen. Counts of neurons in the CN reveal that 50% are lost in grade 1 and that 95% are lost in grade 4; astrocytes are greatly increased in grades 2-4. These studies indicate that analyses of the CN in grade 4 would reflect mainly its astrocytic composition with a component of remote neurons projecting to the striatum. Because of the relative preservation of the lateral half of the head of the CN in grades 1-2, these regions would reflect early cellular and biochemical changes in HD.

2,471 citations


Journal ArticleDOI
01 Jan 1985-Nature
TL;DR: The complete nucleotide sequence of two human T-cell leukaemia type III (HTLV-III) proviral DNAs each have four long open reading frames, the first two corresponding to the gag and pol genes.
Abstract: The complete nucleotide sequence of two human T-cell leukaemia type III (HTLV-III) proviral DNAs each have four long open reading frames, the first two corresponding to the gag and pol genes. The fourth open reading frame encodes two functional polypeptides, a large precursor of the major envelope glycoprotein and a smaller protein derived from the 3′-terminus long open reading frame analogous to the long open reading frame (lor) product of HTLV-I and -II.

2,358 citations


Journal ArticleDOI
05 Jul 1985-Science
TL;DR: Analysis of neighboring aromatic groups in four biphenyl peptides or peptide analogs and 34 proteins reveals a specific aromatic-aromatic interaction that helps stabilize tertiary structure, and 20 percent stabilize quaternary structure.
Abstract: Analysis of neighboring aromatic groups in four biphenyl peptides or peptide analogs and 34 proteins reveals a specific aromatic-aromatic interaction. Aromatic pairs (less than 7 A between phenyl ring centroids) were analyzed for the frequency of pair type, their interaction geometry (separation and dihedral angle), their nonbonded interaction energy, the secondary structural locations of interacting residues, their environment, and their conservation in related molecules. The results indicate that on average about 60 percent of aromatic side chains in proteins are involved in aromatic pairs, 80 percent of which form networks of three or more interacting aromatic side chains. Phenyl ring centroids are separated by a preferential distance of between 4.5 and 7 A, and dihedral angles approaching 90 degrees are most common. Nonbonded potential energy calculations indicate that a typical aromatic-aromatic interaction has energy of between -1 and -2 kilocalories per mole. The free energy contribution of the interaction depends on the environment of the aromatic pair. Buried or partially buried pairs constitute 80 percent of the surveyed sample and contribute a free energy of between -0.6 and -1.3 kilocalories per mole to the stability of the protein's structure at physiologic temperature. Of the proteins surveyed, 80 percent of these energetically favorable interactions stabilize tertiary structure, and 20 percent stabilize quaternary structure. Conservation of the interaction in related molecules is particularly striking.

2,300 citations


Journal ArticleDOI
TL;DR: Clinical observations and psychiatric diagnostic findings of drug-dependent individuals suggest that they are predisposed to addiction because they suffer with painful affect states and related psychiatric disorders.
Abstract: Recent clinical observations and psychiatric diagnostic findings of drug-dependent individuals suggest that they are predisposed to addiction because they suffer with painful affect states and related psychiatric disorders. The drugs that addicts select are not chosen randomly. Their drug of choice is the result of an interaction between the psychopharmacologic action of the drug and the dominant painful feelings with which they struggle. Narcotic addicts prefer opiates because of their powerful muting action on the disorganizing and threatening affects of rage and aggression. Cocaine has its appeal because of its ability to relieve distress associated with depression, hypomania, and hyperactivity.

2,228 citations


Posted Content
TL;DR: In this paper, the authors show that the state of the term structure of interest rates predicts stock returns and that stock returns tend to be low when the short term nominal interest rate is high.
Abstract: It is well known that in the postwar period stockreturns have tended to be low when the short term nominal interest rate is high. In this paper I show that more generally the state of the term structure of interest rates predicts stock returns. Risk premia on stocks appear to move closely together with those on 20-year Treasury bonds, while risk premia on Treasury bills move somewhat independently. Average returns on 20-year bonds have been very low relative to average returns on stocks. I use these observations to test some simple asset pricing models. First I consider latent variable models in which betas are constant and risk premia vary with expected returns on a small number of unobservable hedge portfolios. The data strongly reject a single-latent-variable model.The last part of the paper examines the relationship between conditional means and variances of returns on bills, bonds and stocks. Bill returns tend to be high when their conditional variance is high, but there is a perverse negative relationship between stock returns and their conditional variance. A model is estimated which assumes that asset returns are determined by their time-varying betas with a fixed-weight "benchmark" portfolio of bills, bonds and stocks, whose return is proportional to its conditional variance. This portfolio is estimated to place almost all its weight on bills, indicating that uncertainty about nominal interest rates is important in pricing both short- and long-term assets.

1,915 citations


Journal ArticleDOI
TL;DR: If coronary arteries become vulnerable to occlusion when the intima covering an atherosclerotic plaque is disrupted, the circadian timing of myocardial infarction may result from a variation in the tendency to thrombosis.
Abstract: To determine whether the onset of myocardial infarction occurs randomly throughout the day, we analyzed the time of onset of pain in 2999 patients admitted with myocardial infarction. A marked circadian rhythm in the frequency of onset was detected, with a peak from 6 a.m. to noon (P<0.01). In 703 of the patients, the time of the first elevation in the plasma creatine kinase MB (CK-MB) level could be used to time the onset of myocardial infarction objectively. CK-MB—estimated timing confirmed the existence of a circadian rhythm, with a threefold increase in the frequency of onset of myocardial infarction at peak (9 a.m.) as compared with trough (11 p.m.) periods. The circadian rhythm was not detected in patients receiving beta-adrenergic blocking agents before myocardial infarction but was present in those not receiving such therapy. If coronary arteries become vulnerable to occlusion when the intima covering an atherosclerotic plaque is disrupted, the circadian timing of myocardial infarction ma...

1,797 citations


Book
01 Jan 1985

1,584 citations


Book ChapterDOI
TL;DR: The aim of this chapter is to examine structural and functional roles of turns in peptides and proteins.
Abstract: Publisher Summary Turns are a fundamental class of polypeptide structure and are defined as sites where the peptide chain reverses its overall direction. In the past 20 years, the peptide field has witnessed major development, stimulated by the discovery of a host of bioactive peptides. Turn structures have been proposed and implicated in the bioactivity of several of these naturally occurring peptides. In addition, many structural details of turns have been derived from conformational studies of model peptides. During this same period, more than 100 complete protein structures have been elucidated in single-crystal X-ray studies. These examples document the rich diversity of structural patterns in the chain folds of native proteins. Turns are intrinsically polar structures with backbone groups that pack together closely and side chains that project outward. Such an array of atoms may constitute a site for molecular recognition, and indeed, the literature abounds with suggestions that turns serve as loci for receptor binding, antibody recognition, and post-translational modification. In peptides, turns are the conformations of choice for simultaneously optimizing both backbone–chain compactness (intramolecular nonbonded contacts) and side-chain clustering (to facilitate intermolecular recognition). Presence of turns in bioactive conformations may in fact also reflect the lack of alternative conformational possibilities. The aim of this chapter is to examine structural and functional roles of turns in peptides and proteins.

Journal ArticleDOI
TL;DR: In this paper, the authors discuss methods used in other social sciences and in marketing in terms of two key criteria defining "good research" and argue that the simultaneous research desiderata of data int...
Abstract: The author discusses methods used in other social sciences and in marketing in terms of two key criteria defining “good research.” It is argued that the simultaneous research desiderata of data int...

Journal ArticleDOI
TL;DR: In this paper, the authors combine the strengths of the index approach, namely, simplicity, objectivity and replicability, with the essential richness of Rumelt's methodology, and find that firms with predominantly related diversification show significantly better profit growth than those with predominantly unrelated diversification.
Abstract: Several industrial organization studies, using diversification index measures, examined corporate diversification and economic performance and failed to find any significant relationship between them. Rumelt and other strategy researchers used a semisubjective classification scheme and uncovered a systematic relationship between diversification strategies and performance. This study combines the strengths of the index approach, namely, simplicity, objectivity and replicability, with the essential richness of Rumelt's methodology. Using the Jacquemin-Berry entropy measure of diversification and the line-of-business data, this study finds that firms with predominantly related diversification show significantly better profit growth than firms with predominantly unrelated diversification.

Journal ArticleDOI
TL;DR: A new exact algorithm is presented that considers the CT data as consisting of the intersection volumes of three orthogonal sets of equally spaced, parallel planes, for a three-dimensional CT array of N3 voxels.
Abstract: Ready availability has prompted the use of computed tomography (CT) data in various applications in radiation therapy. For example, some radiation treatment planning systems now utilize CT data in heterogeneous dose calculations algorithms. In radiotherapy imaging applications, CT data are projected onto specified planes, thus producing "radiographs," which are compared with simulator radiographs to assist in proper patient positioning and delineation of target volumes. All these applications share the common geometric problem of evaluating the radiological path through the CT array. Due to the complexity of the three-dimensional geometry and the enormous amount of CT data, the exact evaluation of the radiological path has proven to be a time consuming and difficult problem. This paper identifies the inefficient aspect of the traditional exact evaluation of the radiological path as that of treating the CT data as individual voxels. Rather than individual voxels, a new exact algorithm is presented that considers the CT data as consisting of the intersection volumes of three orthogonal sets of equally spaced, parallel planes. For a three-dimensional CT array of N3 voxels, the new exact algorithm scales with 3N, the number of planes, rather than N3, the number of voxels. Coded in FORTRAN-77 on a VAX 11/780 with a floating point option, the algorithm requires approximately 5 ms to calculate an average radiological path in a 100(3) voxel array.

Book
03 Jan 1985
TL;DR: The first full-scale history of cognitive science is described in this paper, where the authors address a central issue: What is the nature of knowledge, i.e., what is knowledge?
Abstract: The first full-scale history of cognitive science, this work addresses a central issue: What is the nature of knowledge?

Journal ArticleDOI
TL;DR: In this paper, the upward-looking theory of strategy was linked with the downward-looking theories of regimes, and the importance of linking the upward looking theory of policy and strategy with regimes was discussed.
Abstract: Cooperation and discord in world politics are explained to a considerable extent by the three factors discussed in the Introduction: mutuality of interest, the shadow of the future, and the number of players. Yet the context of interaction, perceptions, and strategies is also important. Issues are linked to one another through multilevel games, which may be compatible or incompatible. Whether reciprocity constitutes an effective strategy depends both on linkages among issues and on the institutions within which negotiations take place. Perceptions are always significant and often decisive. Decision makers often actively seek to change the contexts within which they act by linking issues, trying to alter others' perceptions, establishing institutions, and promoting new norms. This finding suggests the importance of linking the upward-looking theory of strategy with the downward-looking theory of regimes.

Journal ArticleDOI
TL;DR: The neuroanatomical findings in 4 consecutively studied brains of men with developmental dyslexia are discussed with reference to developmental cortical anomalies, cerebral asymmetries, reorganization of the brain after early lesions, and the association between learning disorders, left handedness, and diseases of the immune system.
Abstract: We report the neuroanatomical findings in 4 consecutively studied brains of men with developmental dyslexia. The patients, who ranged in age between 14 and 32 years, were diagnosed as dyslexic during life. Nonrighthandedness and several autoimmune and atopic illnesses were present in the personal and family histories. All brains showed developmental anomalies of the cerebral cortex. These consisted of neuronal ectopias and architectonic dysplasias located mainly in perisylvian regions and affecting predominantly the left hemisphere. Furthermore, all brains showed a deviation from the standard pattern of cerebral asymmetry characterized by symmetry of the planum temporale. The neuroanatomical findings in these 4 patients are discussed with reference to developmental cortical anomalies, cerebral asymmetries, reorganization of the brain after early lesions, and the association between learning disorders, left handedness, and diseases of the immune system.

Journal ArticleDOI
David E. Bell1
TL;DR: The implications of disappointment, a psychological reaction caused by comparing the actual outcome of a lottery to one's prior expectations, for decision making under uncertainty, are explored and explicit recognition that decision makers may be paying a premium to avoid potential disappointment is provided.
Abstract: Decision analysis requires that two equally desirable consequences should have the same utility and vice versa. Most analyses of financial decision making presume that two consequences with the same dollar outcome will be equally preferred However, winning the top prize of $10,000 in a lottery may leave one much happier than receiving $10,000 as the lowest prize in a lottery. This paper explores the implications of disappointment, a psychological reaction caused by comparing the actual outcome of a lottery to one's prior expectations, for decision making under uncertainty. Explicit recognition that decision makers may be paying a premium to avoid potential disappointment provides an interpretation for some known behavioral paradoxes, and suggests that decision makers may be sensitive to the manner in which a lottery is resolved. The concept of disappointment is integrated into utility theory in a prescriptive model.

Journal ArticleDOI
TL;DR: It is suggested that television viewing may cause obesity in at least some children and adolescents and the potential effects of obesity on activity and the consumption of calorically dense foods are consistent with this hypothesis.
Abstract: The association of television viewing and obesity in data collected during cycles II and III of the National Health Examination Survey was examined. Cycle II examined 6,965 children aged 6 to 11 years and cycle III examined 6,671 children aged 12 to 17 years. Included in the cycle III sample were 2,153 subjects previously studied during cycle II. These surveys, therefore, provided two cross-sectional samples and one prospective sample. In all three samples, significant associations of the time spent watching television and the prevalence of obesity were observed. In 12- to 17-year-old adolescents, the prevalence of obesity increased by 2% for each additional hour of television viewed. The associations persisted when controlled for prior obesity, region, season, population density, race, socioeconomic class, and a variety of other family variables. The consistency, temporal sequence, strength, and specificity of the associations suggest that television viewing may cause obesity in at least some children and adolescents. The potential effects of obesity on activity and the consumption of calorically dense foods are consistent with this hypothesis.

Journal ArticleDOI
01 Jan 1985-Nature
TL;DR: A physical association of this peptide responsible for T-cell recognition of HEL is sought with purified, detergent-solubilized I–Ak molecules from B-hybridoma cells, which may explain the role of the Ia glycoproteins in cellular interactions.
Abstract: Most cellular interactions essential for the development of an immune response involve the membrane glycoproteins encoded in the major histocompatibility gene complex. The products of the I region, the class II histocompatibility molecules (Ia molecules), are essential for accessory cells such as macrophages to present polypeptide antigens to helper T cells. This interaction, antigen presentation, is needed for T-cell recognition of the antigen and its consequent activation. How the Ia molecules regulate the immune response during antigen presentation is not known, although it is commonly thought to result from their association with the presented antigen. Recent studies, including the elucidation of the structure of the T-cell receptor, favour recognition of a single structure, an antigen-Ia complex. Here we report attempts to determine whether purified Ia glycoproteins have an affinity for polypeptide antigens presented by intact cells in an Ia-restricted manner. We first identified the epitope of a peptide antigen involved in presentation. Several laboratories have shown that globular proteins are altered (processed) in intracellular vesicles of the antigen-presenting cell before antigen presentation. A major component of the T-cell response is directed toward determinants found in the unfolded or denatured molecule, and our laboratory has shown that the determinant of the hen-egg lysozyme protein (HEL), presented in H-2k mice to T cells, is a sequence of only 10 amino acids. This portion resides in an area of the native molecule partially buried inside the molecule, in a beta-sheet conformation. To be presented, intact or native HEL must first be processed in acidic intracellular vesicles. Having isolated the peptide responsible for T-cell recognition of HEL, we sought a physical association of this peptide with purified, detergent-solubilized I-Ak molecules from B-hybridoma cells. We have found such an association, which may explain the role of the Ia glycoproteins in cellular interactions.

Journal ArticleDOI
TL;DR: In this paper, two modes of seasonal behavior are noted for surface ozone at mid-latitudes: a broad summer maximum within a few hundred km of industrial/urban areas in Europe and the U.S., and a minimum in summer or autumn in sparcely populated regions that are remote from industrial activity.
Abstract: In the present analysis of tropospheric ozone data, attention is given to spatial and temporal variations. Two modes of seasonal behavior are noted for surface ozone at mid-latitudes: a broad summer maximum within a few hundred km of industrial/urban areas in Europe and the U.S., and a minimum in summer or autumn in sparcely populated regions that are remote from industrial activity. These and limited historical data indicate that summertime concentrations of ozone near the surface in the rural areas of Europe and the U.S. may have increased between 20 and 100 percent since the 1940s. It is suggested that the summer maximum in ozone and other observed trends are due to photochemical production associated with anthropogenic emissions of NO(x), hydrocarbons, and CO from fossil fuel combustion.

Journal ArticleDOI
07 Jun 1985-Science
TL;DR: The isolation of a T-cell tropic retrovirus from three immunodeficient macaques and one macaque with lymphoma is described, and it is indicated that it is related to the causative agent of acquired immune deficiency syndrome in humans.
Abstract: The isolation of a T-cell tropic retrovirus from three immunodeficient macaques and one macaque with lymphoma is described. The morphology, growth characteristics, and antigenic properties of this virus indicate that it is related to the causative agent of acquired immune deficiency syndrome in humans (HTLV-III or LAV). This virus is referred to as simian T-lymphotropic virus type III (STLV-III) of macaques. The existence of a cytopathic, T-cell tropic virus resembling HTLV-III in monkeys may facilitate study of disease induction and vaccine development in an animal model.

Journal ArticleDOI
TL;DR: This paper examines comparative analysis of rates with a view to each of the usual comparative parameters-rate difference, rate ratio and odds ratio with particular reference to first principles, and stresses the need for restricted estimation of variance in the chi-square function underlying interval estimation.
Abstract: In this paper, we examine comparative analysis of rates with a view to each of the usual comparative parameters-rate difference (RD), rate ratio (RR) and odds ratio (OR)-and with particular reference to first principles. For RD and RR we show the prevailing statistical practices to be rather poor. We stress the need for restricted estimation of variance in the chi-square function underlying interval estimation (and also point estimation and hypothesis testing). For RR analysis we propose a chi-square formulation analogous to that for RD and, thus, one which obviates the present practice of log transformation and its associated use of Taylor series approximation of the variance. As for OR analysis, we emphasize that the chi-square function, introduced by Cornfield for unstratified data, and extended by Gart to the case of stratified analysis, is based on the efficient score and thus embodies its optimality properties. We provide simulation results to evince the better performance of the proposed (parameter-constrained) procedures over the traditional ones.

Journal ArticleDOI
TL;DR: In this paper, a Principal Component Analysis (PCA) of paniculate elemental data is employed to identify and quantify the major particle pollution source classes affecting a monitoring site in metropolitan Boston, MA.

Journal ArticleDOI
TL;DR: It is suggested that control of glomerular hypertension effectively limits glomersular injury in rats with renal ablation, and the view thatglomerular hemodynamic changes mediate progressive renal injury when nephron number is reduced is supported.
Abstract: Micropuncture and morphologic studies were performed in four groups of male Munich-Wistar rats after removal of the right kidney and segmental infarction of two-thirds of the left kidney. Groups 1 and 3 received no specific therapy. Groups 2 and 4 were treated with the angiotensin I converting enzyme inhibitor, enalapril, 50 mg/liter of which was put in their drinking water. All rats were fed standard chow. Groups 1 and 2 underwent micropuncture study 4 wk after renal ablation. Untreated group 1 rats exhibited systemic hypertension and elevation of the single nephron glomerular filtration rate (SNGFR) due to high average values for the mean glomerular transcapillary hydraulic pressure difference and glomerular plasma flow rate. In group 2 rats, treatment with enalapril prevented systemic hypertension and maintained the mean glomerular transcapillary hydraulic pressure gradient at near-normal levels without significantly compromising SNGFR and the glomerular capillary plasma flow rate, as compared with untreated group 1 rats. Groups 3 and 4 were studied 8 wk after renal ablation. Untreated group 3 rats demonstrated persistent systemic hypertension, progressive proteinuria, and glomerular structural lesions, including mesangial expansion and segmental sclerosis. In group 4 rats, treatment with enalapril maintained systemic blood pressure at normal levels over the 8-wk period and significantly limited the development of proteinuria and glomerular lesions. These studies suggest that control of glomerular hypertension effectively limits glomerular injury in rats with renal ablation, and further support the view that glomerular hemodynamic changes mediate progressive renal injury when nephron number is reduced.

Journal ArticleDOI
Kim B. Clark1
TL;DR: In this article, a conceptual framework for analyzing the sequence of technological changes that underlie the development of industries is presented, which examines the interaction between design decisions and the coices of customers.

Journal ArticleDOI
TL;DR: The formation of the CHILDES, the governance of the system, the nature of the database, the shape of the coding conventions, and the types of computer programs being developed are detailed.
Abstract: The study of language acquisition underwent a major revolution in the late 1950s as a result of the dissemination of technology permitting high-quality tape-recording of children in the family setting. This new technology led to major breakthroughs in the quality of both data and theory. The field is now at the threshold of a possible second major breakthrough stimulated by the dissemination of personal computing. Researchers are now able to transcribe tape-recorded data into computer files. With this new medium it is easy to conduct global searches for word combinations across collections of files. It is also possible to enter new codings of the basic text line. Because of the speed and accuracy with which computer files can be copied, it is now much easier to share data between researchers. To foster this sharing of computerized data, a group of child language researchers has established the Child Language Data Exchange System (CHILDES). This article details the formation of the CHILDES, the governance of the system, the nature of the database, the shape of the coding conventions, and the types of computer programs being developed.

Posted Content
TL;DR: This article used survey data and the technique of bootstrapping to test a number of propositions of interest, such as the expected future spot rate can be viewed as inelastic with respect to the contemporaneous spot rate, in that it also puts weight on other variables: the lagged expected spot rate (as in adaptive expectations), the distributed lag expectations, or a long-run equilibrium rate (regressive expectations).
Abstract: Survey data provide a measure of exchange rate expectations that is superior to the commonly-used forward exchange rate in the respect that it does notinclude a risk premium. We use survey data and the technique of bootstrapping to test a number of propositions of interest. We are able to reject static or "randomwalk" expectations for both nominal and real exchange rates. Expected depreciation is large in magnitude. There is even statistically significant unconditional bias: during the 1981-85 "strong dollar period" the market persistently over estimated depreciation of the dollar. Expected depreciation is also variable, contrary to some recent claims. The expected future spot rate can be viewed as inelastic with respect to the contemporaneous spot rate, in that it also puts weight on other variables: the lagged expected spot rate (as in adaptive expectations), the lagged actual spot rate (distributed lag expectations), or a long-run equilibrium rate (regressive expectations). In one irnportant case, the relatively low weight that investors' expectations put on the contemporaneous spot rate constitutes a statistical rejection of rational expectations: we find that prediction errors are correlated with expected depreciation, so that investors would do better if they always reduced fractionally the magnitude of expected depreciation. This is the same result found by Bilson, Fama, and many others, except that it can no longer be attributed to a risk premium.

Journal ArticleDOI
TL;DR: In this article, it was shown that the global fractal dimension of a self-affine fractal curve can be computed by walking a compass along the fractal path of a scalar Bownian record.
Abstract: Evaluating a fractal curve's approximate length by walking a compass defines a compass exponent. Long ago, I showed that for a self-similar curve (e.g., a model of coastline), the compass exponent coincides with all the other forms of the fractal dimension, e.g., the similarity, box or mass dimensions. Now walk a compass along a self-affine curve, such as a scalar Brownian record B(t). It will be shown that a full description in terms of fractal dimension is complex. Each version of dimension has a local and a global value, separated by a crossover. First finding: the basic methods of evaluating the global fractal dimension yield 1: globally, a self-affine fractal behaves as it if were not fractal. Second finding: the box and mass dimensions are 1.5, but the compass dimension is D = 2. More generally, for a fractional Bownian record BH(t), (e.g., a model of vertical cuts of relief), the global fractal dimensions are 1, several local fractal dimensions are 2-H, and the compass dimension is 1/H. This 1/H is the fractal dimension of a self-similar fractal trail, whose definition was already implicit in the definition of the record of BH(t).

Journal ArticleDOI
01 Nov 1985-Science
TL;DR: A distinct subpopulation of striatal aspiny neurons, containing the enzyme nicotinamide adenine dinucleotide phosphate diaphorase, is preserved in the caudate nucleus in Huntington's disease, and the resistance of these neurons suggests that the gene defect in Huntington't disease may be modifiable by the local biochemical environment.
Abstract: A distinct subpopulation of striatal aspiny neurons, containing the enzyme nicotinamide adenine dinucleotide phosphate diaphorase, is preserved in the caudate nucleus in Huntington's disease. Biochemical assays confirmed a significant increase in the activity of this enzyme in both the caudate nucleus and putamen in postmortem brain tissue from patients with this disease. The resistance of these neurons suggests that the gene defect in Huntington's disease may be modifiable by the local biochemical environment. This finding may provide insight into the nature of the genetically programmed cell death that is a characteristic of the disease.