Showing papers by "Columbia University published in 1993"

Evidence for general instability of past climate from a 250-kyr ice-core record

Abstract: RECENT results1,2 from two ice cores drilled in central Greenland have revealed large, abrupt climate changes of at least regional extent during the late stages of the last glaciation, suggesting that climate in the North Atlantic region is able to reorganize itself rapidly, perhaps even within a few decades. Here we present a detailed stable-isotope record for the full length of the Greenland Ice-core Project Summit ice core, extending over the past 250 kyr according to a calculated timescale. We find that climate instability was not confined to the last glaciation, but appears also to have been marked during the last interglacial (as explored more fully in a companion paper3) and during the previous Saale–Holstein glacial cycle. This is in contrast with the extreme stability of the Holocene, suggesting that recent climate stability may be the exception rather than the rule. The last interglacial seems to have lasted longer than is implied by the deep-sea SPECMAP record4, in agreement with other land-based observations5,6. We suggest that climate instability in the early part of the last interglacial may have delayed the melting of the Saalean ice sheets in America and Eurasia, perhaps accounting for this discrepancy.

National Innovation Systems: A Comparative Analysis

Abstract: This anthology examines national systems of technical innovation An introductory chapter provides an overview of the principal topics in current discussion of industrial and technology policy Innovation is defined as the processes by which firms master and put into practice product designs and manufacturing processes that are new to them A wide range of factors, organizations, and policies influence the capabilities of a nation's firms to innovate Technology and pure science are distinguished, and the social institutions that play a role in innovation are examined These include industrial and government research laboratories, research universities, and industrial policy agencies These institutions provide the core for the analyses of national innovation systems Individual chapters are devoted to six large high-income countries (France, Italy, Japan, the US, the UK, and West Germany), four smaller high-income countries (Australia, Canada, Denmark, and Sweden), and five lower income countries (Argentina, Brazil, Israel, Korea, and Taiwan) Each chapter is a detailed description of each country's structure and behavior in the development of product and process technologies, and catalogues the innovation strategies of each country, covering topics including historical analysis of technological development, breakdown of industries, and investigation of these institutions in terms of R&D expenditures and their influence Differences in the innovative patterns include size and resource endowments, national security considerations, and historical and social beliefs Factors leading to effective innovative performance include strong core competencies, high-quality education and training, and stable and facilitative economic and trade policies A final retrospective chapter compares and contrasts the various innovation systems It assesses whether identifying an innovation system is useful, considers whether national institutions matter when commerce and technology are becoming transnational, and reflects on the future of national systems in such a world (TNM)

Incidence of Epilepsy and Unprovoked Seizures in Rochester, Minnesota: 1935–1984

Abstract: The incidence of epilepsy and of all unprovoked seizures was determined for residents of Rochester, Minnesota U.S.A. from 1935 through 1984. Age-adjusted incidence of epilepsy was 44 per 100,000 person-years. Incidence in males was significantly higher than in females and was high in the first year of life but highest in persons aged > or = 75 years. Sixty percent of new cases had epilepsy manifested by partial seizures, and two thirds had no clearly identified antecedent. Cerebrovascular disease was the most commonly identified antecedent, accounting for 11% of cases. Neurologic deficits from birth, mental retardation and/or cerebral palsy, observed in 8% of cases, was the next most frequently identified preexisting condition. The cumulative incidence of epilepsy through age 74 years was 3.1%. The age-adjusted incidence of all unprovoked seizures was 61 per 100,000 person-years. Age- and gender-specific incidence trends were similar to those of epilepsy, but a higher proportion of cases was of unknown etiology and was characterized by generalized onset seizures. The cumulative incidence of all unprovoked seizures was 4.1% through age 74 years. With time, the incidence of epilepsy and of unprovoked seizures decreased in children and increased in the elderly.

Quality of Life Enjoyment and Satisfaction Questionnaire: A New Measure.

Abstract: The Quality of Life Enjoyment and Satisfaction Questionnaire (Q-LES-Q) is a self-report measure designed to enable investigators to easily obtain sensitive measures of the degree of enjoyment and satisfaction experienced by subjects in various areas of daily functioning. The summary scores were found to be reliable and valid measures of these dimensions in a group of depressed outpatients. The Q-LES-Q measures were related to, but not redundant with, measures of overall severity of illness or severity of depression within this sample. These findings suggest that the Q-LES-Q measures may be sensitive to important differences among depressed patients that are not detected by the measures usually employed.

Do Neighborhoods Influence Child and Adolescent Development

Abstract: The effects of neighborhood characteristics on the development of children and adolescents are estimated, using two data sets, each of which contains information gathered about individual children and the families and neighborhoods in which they reside. There are reasonably powerful neighborhood effects-particularly effects of the presence of affluent neighbors-on Childhood IQ, teenage births, and school-leaving, even after the differences in the socioeconomic characteristics of families are adjusted for. The study finds that white teenagers benefit more from the presence of affluent neighbors than do black teenagers.

Antisense oligonucleotides as therapeutic agents--is the bullet really magical?

Abstract: Because of the specificity of Watson-Crick base pairing, attempts are now being made to use oligodeoxynucleotides (oligos) in the therapy of human disease. However, for a successful outcome, the oligo must meet at least six criteria: (i) the oligos can be synthesized easily and in bulk; (ii) the oligos must be stable in vivo; (iii) the oligos must be able to enter the target cell; (iv) the oligos must be retained by the target cell; (v) the oligos must be able to interact with their cellular targets; and (vi) the oligos should not interact in a non-sequence-specific manner with other macromolecules. Phosphorothioate oligos are examples of oligos that are being considered for clinical therapeutic trials and meet some, but not all, of these criteria. The potential use of phosphorothioate oligos as inhibitors of viral replication is highlighted.

Reproductive Factors and Breast Cancer

Abstract: PIP: Early age at menarche, late age at menopause, and late age at first full-term pregnancy are linked to a modest increase in the risk of developing breast cancer. Some evidence suggests that the earlier the full-term pregnancy, the earlier the period of decreased susceptibility of breast tissue changes begins. Nulliparity is related to an increased risk for breast cancer diagnosed after 40 years old. Multiple full-term pregnancies decrease the risk of breast cancers diagnosed after 40 years regardless of the age at first birth. On the other hand, they may increase the risk for breast cancers diagnosed before 40 years old. Surgical removal of the ovaries protects against breast cancer. Breast feeding apparently protects against breast cancer in China, but a protective effect has not been established in the US. Other than shorter intervals between menstrual periods, which tend to increase the risk, research has not yet made clear the etiologic roles of menstrual cycle characteristics. Other unclear etiologic roles include increased intervals between births, spontaneous and induced abortion, infertility, multiple births at last pregnancy, and hypertension during pregnancy. Researchers tend to accept a mechanism to explain the epidemiologic characteristics of menstrual activity and the increased risk of breast cancer, but no mechanisms have emerged for the other likely risk factors. Greater exposure to estrogen and progesterone simultaneously are linked to early age at menarche, late age at menopause, and shorter menstrual cycle length. So far, data show that long-term combined estrogen/progestin hormone replacement therapy and long-term use of oral contraceptives increase the risk of breast cancer. Moderately increased risks linked to longterm estrogen replacement therapy and obesity in postmenopausal women indicate that estrogen alone influences breast cancer risk. Since much of the research on breast cancer risk factors are inconclusive, more research is needed, especially research examining the probability of prolonged exposure to both estrogens and progesterone concurrently.

Medical Hazards of Obesity

Abstract: The medical hazards of obesity are discussed. Risks include insulin resistance, diabetes mellitus, hypertriglyceridemia, decreased levels of high-density lipoprotein cholesterol, and increased levels of low-density lipoprotein cholesterol. Obesity is also associated with gallbladder disease and some forms of cancer as well as sleep apnea, chronic hypoxia and hypercapnia, and degenerative joint disease. Obesity is an independent risk factor for death from coronary heart disease. A central distribution of body fat enhances the risk for most of these conditions.

False suffocation alarms, spontaneous panics, and related conditions. An integrative hypothesis.

Abstract: • A carbon dioxide hypersensitivity theory of panic has been posited. We hypothesize more broadly that a physiologic misinterpretation by a suffocation monitor misfires an evolved suffocation alarm system. This produces sudden respiratory distress followed swiftly by a brief hyperventilation, panic, and the urge to flee. Carbon dioxide hypersensitivity is seen as due to the deranged suffocation alarm monitor. If other indicators of potential suffocation provoke panic, this theoretical extension is supported. We broadly pursue this theory by examining Ondine's curse as the physiologic and pharmacologic converse of panic disorder, splitting panic in terms of symptomatology and challenge studies, reevaluating the role of hyperventilation, and reinterpreting the contagiousness of sighing and yawning, as well as mass hysteria. Further, the phenomena of panic during relaxation and sleep, late luteal phase dysphoric disorder, pregnancy, childbirth, pulmonary disease, separation anxiety, and treatment are used to test and illuminate the suffocation false alarm theory.

Institutional and competitive bandwagons: using mathematical modeling as a tool to explore innovation diffusion

Abstract: The sheer number of organizations adopting an innovation can cause a bandwagon pressure, prompting other organizations to adopt this innovation Institutional bandwagon pressures occur because nonadopters fear appearing different from many adopters Competitive bandwagon pressures occur because nonadopters fear below-average performance if many competitors profit from adopting Our mathematical model of bandwagons examines how organizational collectivities' characteristics determine (a) whether a bandwagon will occur, (b) how many organizations jump on it, and (c) how many retain the Innovation it diffuses Simulating the model suggests, first, that any technological, organizational, or strategic innovation with ambiguous returns can diffuse in a bandwagon manner; second, that minor differences in organizational collectivities can have major effects on bandwagons' occurrence, extent, and persistence: and third, that bandwagons can prompt most organizations in a collectivity to adopt an innovation, even wh

Gastrointestinal approximating and tissue attaching device

Abstract: An intestinal steerable endoscopic stapler for stapling tubular tissue is provided comprising a circular anvil member having a circular anvil stapling surface and a cutting block surface radially inwardly of the stapling surface. A head assembly has a circular staple driver for driving staples in an array corresponding to the anvil surface and a circular cutting blade corresponding to the cutting block. A flexible tube has a distal end at the head assembly and a handpiece end. A scope in the form of an eyepiece in the handpiece optically connected to a lens in the head assembly is provided for viewing a region of space beyond the head assembly. A steering arrangement is provided for pivoting the head assembly relative the flexible tube to thereby steer the head assembly in a body cavity. A stapler activator is provided located at the handpiece end for driving staples from the head assembly toward the anvil member and for driving the cutting blade toward the cutting block, whereby two ends of tubular tissue may be joined by an array of staples and excess tubular tissue ends may be trimmed off with the cutting blade. A number of tissue approximating devices are also disclosed.

Top executive commitment to the status quo: some tests of its determinants

Abstract: Some top executives are more committed to the status quo—particularly to their organization's current strategy and leadership profile—than are others. Most empirical research on upper echelons treats psychological phenomena as a ‘black box’—the unobserved intervening mechanisms—that causes associations between more observable executive characteristics and organizational outcomes. In contrast, this paper attempts to directly examine the determinants of an important element of an executive's psychological orientation—commitment to the status quo (CSQ). We focus on a select set of variables which have been posited in prior research as determinants of executive CSQ, but which have not been directly tested for such a relationship. Based on a large-scale survey methodology, results suggest that an executive's tenure in an industry is a pronounced determinant of CSQ, and has significantly more impact than organizational tenure. As expected, the firm's current performance was found to be positively related to CSQ; this relationship was stronger in high-discretion than in low-discretion industries. Finally, the project reaffirms a well known human tendency: incumbent CEOs tend to believe that their eventual successors should be just like them.

An Epidemiological Study of Disorders in Late Childhood and Adolescence—I. Age‐ and Gender‐Specific Prevalence

Abstract: Developmental aspects of psychiatric disorders may be inferred from patterns of age differences in prevalence. Age-specific prevalences are provided for nine disorders in a general population sample of ages 10-20. Age and gender patterns for several disorders suggest developmental stage-associated risks. These include oppositional disorder in both genders and conduct disorder and major depression in girls. Major depression shows a pattern suggestive of a role for the onset of puberty. The prevalence of one or more disorders did not differ by age or gender. However, the pattern of specific diagnoses varied greatly by both age and gender.

Retrieving collocations from text: Xtract

Abstract: Natural languages are full of collocations, recurrent combinations of words that co-occur more often than expected by chance and that correspond to arbitrary word usages. Recent work in lexicography indicates that collocations are pervasive in English; apparently, they are common in all types of writing, including both technical and nontechnical genres. Several approaches have been proposed to retrieve various types of collocations from the analysis of large samples of textual data. These techniques automatically produce large numbers of collocations along with statistical figures intended to reflect the relevance of the associations. However, none of these techniques provides functional information along with the collocation. Also, the results produced often contained improper word associations reflecting some spurious aspect of the training corpus that did not stand for true collocations.In this paper, we describe a set of techniques based on statistical methods for retrieving and identifying collocations from large textual corpora. These techniques produce a wide range of collocations and are based on some original filtering methods that allow the production of richer and higher-precision output. These techniques have been implemented and resulted in a lexicographic tool, Xtract. The techniques are described and some results are presented on a 10 million-word corpus of stock market news reports. A lexicographic evaluation of Xtract as a collocation retrieval tool has been made, and the estimated precision of Xtract is 80%.

Long-range photoinduced electron transfer through a DNA helix

Abstract: Rapid photoinduced electron transfer is demonstrated over a distance of greater than 40 angstroms between metallointercalators that are tethered to the 5' termini of a 15-base pair DNA duplex. An oligomeric assembly was synthesized in which the donor is Ru(phen)2dppz2+ (phen, phenanthroline, and dppz, dipyridophenazine) and the acceptor is Rh(phi)2phen3+ (phi, phenanthrenequinone diimine). These metal complexes are intercalated either one or two base steps in from the helix termini. Although the ruthenium-modified oligonucleotide hybridized to an unmodified complement luminesces intensely, the ruthenium-modified oligomer hybridized to the rhodium-modified oligomer shows no detectable luminescence. Time-resolved studies point to a lower limit of 10(9) per second for the quenching rate. No quenching was observed upon metallation of two complementary octamers by Ru(phen)3(2+) and Rh(phen)3(3+) under conditions where the phen complexes do not intercalate. The stacked aromatic heterocycles of the DNA duplex therefore serve as an efficient medium for coupling electron donors and acceptors over very long distances.

Political Equilibrium, Income Distribution, and Growth

Abstract: This paper analyzes the impact of income distribution on growth when investment in human capital is the source of growth and individuals vote over the degree of redistribution in the economy. The model has three main features. First, very different patterns of income distribution are conducive to high growth at different levels of per capita income. Second, growth is associated with an externality whereby investment in human capital by one group increases the productivity of other groups, thus potentially enabling them to invest in human capital. Third, the initial pattern of income distribution and the resulting political equilibrium are crucial in determining whether the transmission of this externality is promoted, in which case growth is enhanced, or prevented, in which case growth is stopped. Using a non-overlapping generations model with voting, I derive several empirical implications. In particular, the model implies an inverted-U relation between levels of inequality and levels of income in cross-sections, but not necessarily in time series, a result that seems consistent with a number of empirical studies.

Expression of the c-ret proto-oncogene during mouse embryogenesis

Abstract: The c-ret proto-oncogene encodes a receptor tyrosine kinase whose normal function has yet to be determined. To begin to investigate the potential role of this gene in vertebrate development, we have isolated cDNA clones representing the murine c-ret gene, and have analyzed the pattern of expression during mouse embryogenesis, using northern blotting, in situ hybridization to histological sections and whole-mount hybridization histochemistry. c-ret transcripts were detected beginning at day 8.5 of embryogenesis, and were observed in a number of cell lineages in the developing peripheral and central nervous systems, as well as in the excretory system. In the cranial region at day 8.5-9.5, c-ret mRNA was restricted to a population of neural crest cells migrating from rhombomere 4 and forming the anlage of the facioacoustic ganglion, as well as to a closely associated domain of surface ectoderm and pharyngeal endoderm. At later stages (10.5-14.5 days), c-ret mRNA was observed in all cranial ganglia. In the peripheral nervous system of the trunk, c-ret was expressed in the autonomic ganglia and in subsets of cells in the dorsal root ganglia. In the enteric nervous system, c-ret was expressed in the presumptive enteric neuroblasts of the vagal crest (day 9.0-11.5), and in the myenteric ganglia of the gut (day 13.5-14.5). c-ret mRNA was observed in several regions of the central nervous system, including the undifferentiated neuroepithelial cells of the ventral neural tube (8.5 days), the motor neurons in the spinal cord and the hindbrain (10.5-14.5 days), the embryonic neuroretina (day 13.5) and the layers of the postnatal retina containing ganglion, amacrine and horizontal cells. Outside the nervous system, c-ret was expressed in the nephric (Wolffian) duct at day 8.5-10.5, the ureteric bud epithelium (but not the surrounding metanephric mesenchyme) at day 11.0-11.5, and the growing tips of the renal collecting ducts (but not the previously formed, subcortical portions of the collecting ducts, or the mesenchyme-derived renal vesicles) at day 13.5-17.5. Our results suggest that the c-ret gene may encode the receptor for a factor involved in the proliferation, migration, differentiation or survival of a variety of neuronal cell lineages, as well as in inductive interactions during organogenesis of the kidney.

Structural changes accompanying memory storage

Abstract: Perhaps the most striking finding in the biology of memory is that long-term memory involves structural changes. A variety of memory processes ranging in complexity from those produced by elementary forms of nonassociative learning in invertebrates to those produced by higher order associative tasks in mammals are accompanied by alterations in the structure of synaptic connections. This finding raises three interesting conceptual issues. First, how does short-term memory, which involves only covalent modification of pre-existing proteins and an alteration of pre-existing connections, become transformed into a structural change? Second, is the stability of long-term memory achieved because of the stability of synaptic structures? If so, is loss of memory with time reflected in loss of synaptic connections? Finally, how do the structural changes that accompany long-term memory compare with the de novo synapse formation and synaptic pruning that occur during development? In this review we consider the recent evidence for structural changes in learning by focusing on these three issues. We begin by examining

Binge eating disorder: its further validation in a multisite study.

Abstract: Binge eating disorder (BED) is a new eating disorder that describes the eating disturbance of a large number of individuals who suffer from recurrent binge eating but who do not regularly engage in the compensatory behaviors to avoid weight gain seen in bulimia nervosa. This multisite study of BED involved 1,785 subjects drawn from 18 weight control programs, 942 subjects from five nonpatient community samples, and 75 patients with bulimia nervosa. Approximately 29% of subjects in weight control programs met the criteria for BED. In the nonpatient community samples BED was more common than purging bulimia nervosa. The validity of BED was supported by its strong association with (1) impairment in work and social functioning, (2) overconcern with body/shape and weight, (3) general psychopathology, (4) significant amount of time in adult life on diets, (5) a history of depression, alcohol/drug abuse, and treatment for emotional problems.

Best wavelet packet bases in a rate-distortion sense

Abstract: A fast rate-distortion (R-D) optimal scheme for coding adaptive trees whose individual nodes spawn descendents forming a disjoint and complete basis cover for the space spanned by their parent nodes is presented. The scheme guarantees operation on the convex hull of the operational R-D curve and uses a fast dynamic programing pruning algorithm to markedly reduce computational complexity. Applications for this coding technique include R. Coefman et al.'s (Yale Univ., 1990) generalized multiresolution wavelet packet decomposition, iterative subband coders, and quadtree structures. Applications to image processing involving wavelet packets as well as discrete cosine transform (DCT) quadtrees are presented. >

Framing, Probability Distortions, and Insurance Decisions

Abstract: A series of studies examines whether certain biases in probability assessments and perceptions of loss, previously found in experimental studies, affect consumers' decisions about insurance. Framing manipulations lead the consumers studied here to make hypothetical insurance-purchase choices that violate basic laws of probability and value. Subjects exhibit distortions in their perception of risk and framing effects in evaluating premiums and benefits. Illustrations from insurance markets suggest that the same effects occur when consumers make actual insurance purchases.

Depression in adolescence.

Abstract: Adolescence is an important developmental period for understanding the nature, course, and treatment of depression. Recent research concerned with depressive mood, syndromes, and disorders during adolescence is reviewed, including investigations of the prevalence, course, risk factors, and prevention and treatment programs for each of these three levels of depressive phenomena in adolescence. A broad biopsychosocial perspective on adolescent depression is recommended, and possible directions for future integrative research are proposed. Based on current research and knowledge, implications for research, program, and national policy are considered.