Showing papers by "Columbia University published in 2001"
TL;DR: In addition to making criteria-based diagnoses of depressive disorders, the PHQ-9 is also a reliable and valid measure of depression severity, which makes it a useful clinical and research tool.
Abstract: OBJECTIVE: While considerable attention has focused on improving the detection of depression, assessment of severity is also important in guiding treatment decisions. Therefore, we examined the validity of a brief, new measure of depression severity.
26,004 citations
TL;DR: In this article, the authors examine two aspects of brand loyalty, purchase loyalty and attitudinal loyalty, as linking variables in the chain of effects from brand trust and brand affect to brand performance (market share and relative price).
Abstract: The authors examine two aspects of brand loyalty, purchase loyalty and attitudinal loyalty, as linking variables in the chain of effects from brand trust and brand affect to brand performance (market share and relative price). The model includes product-level, category-related controls (hedonic value and utilitarian value) and brand-level controls (brand differentiation and share of voice). The authors compile an aggregate data set for 107 brands from three separate surveys of consumers and brand managers. The results indicate that when the product- and brand-level variables are controlled for, brand trust and brand affect combine to determine purchase loyalty and attitudinal loyalty. Purchase loyalty, in turn, leads to greater market share, and attitudinal loyalty leads to a higher relative price for the brand. The authors discuss the managerial implications of these results.
5,428 citations
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TL;DR: This article proposed the risk-as-feelings hypothesis, which highlights the role of affect experienced at the moment of decision making, and showed that emotional reactions to risky situations often diverge from cognitive assessments of those risks.
Abstract: Virtually all current theories of choice under risk or uncertainty are cognitive and consequentialist. They assume that people assess the desirability and likelihood of possible outcomes of choice alternatives and integrate this information through some type of expectation-based calculus to arrive at a decision. The authors propose an alternative theoretical perspective, the risk-as-feelings hypothesis, that highlights the role of affect experienced at the moment of decision making. Drawing on research from clinical, physiological, and other subfields of psychology, they show that emotional reactions to risky situations often diverge from cognitive assessments of those risks. When such divergence occurs, emotional reactions often drive behavior. The risk-as-feelings hypothesis is shown to explain a wide range of phenomena that have resisted interpretation in cognitive-consequentialist terms.
4,647 citations
TL;DR: It is demonstrated that in some cases random graphs with appropriate distributions of vertex degree predict with surprising accuracy the behavior of the real world, while in others there is a measurable discrepancy between theory and reality, perhaps indicating the presence of additional social structure in the network that is not captured by the random graph.
Abstract: Recent work on the structure of social networks and the internet has focused attention on graphs with distributions of vertex degree that are significantly different from the Poisson degree distributions that have been widely studied in the past. In this paper we develop in detail the theory of random graphs with arbitrary degree distributions. In addition to simple undirected, unipartite graphs, we examine the properties of directed and bipartite graphs. Among other results, we derive exact expressions for the position of the phase transition at which a giant component first forms, the mean component size, the size of the giant component if there is one, the mean number of vertices a certain distance away from a randomly chosen vertex, and the average vertex-vertex distance within a graph. We apply our theory to some real-world graphs, including the worldwide web and collaboration graphs of scientists and Fortune 1000 company directors. We demonstrate that in some cases random graphs with appropriate distributions of vertex degree predict with surprising accuracy the behavior of the real world, while in others there is a measurable discrepancy between theory and reality, perhaps indicating the presence of additional social structure in the network that is not captured by the random graph.
3,655 citations
TL;DR: The use of a left ventricular assist device in patients with advanced heart failure resulted in a clinically meaningful survival benefit and an improved quality of life.
Abstract: Background Implantable left ventricular assist devices have benefited patients with end-stage heart failure as a bridge to cardiac transplantation, but their long-term use for the purpose of enhancing survival and the quality of life has not been evaluated. Methods We randomly assigned 129 patients with end-stage heart failure who were ineligible for cardiac transplantation to receive a left ventricular assist device (68 patients) or optimal medical management (61). All patients had symptoms of New York Heart Association class IV heart failure. Results Kaplan–Meier survival analysis showed a reduction of 48 percent in the risk of death from any cause in the group that received left ventricular assist devices as compared with the medical-therapy group (relative risk, 0.52; 95 percent confidence interval, 0.34 to 0.78; P=0.001). The rates of survival at one year were 52 percent in the device group and 25 percent in the medical-therapy group (P=0.002), and the rates at two years were 23 percent and 8 percent...
3,540 citations
TL;DR: It is suggested that pediatric CT will result in significantly increased lifetime radiation risk over adult CT, both because of the increased dose per milliampere-second, and the increased lifetime risk per unit dose.
Abstract: OBJECTIVE. In light of the rapidly increasing frequency of pediatric CT examinations, the purpose of our study was to assess the lifetime cancer mortality risks attributable to radiation from pediatric CT.MATERIALS AND METHODS. Organ doses as a function of age-at-diagnosis were estimated for common CT examinations, and estimated attributable lifetime cancer mortality risks (per unit dose) for different organ sites were applied. Standard models that assume a linear extrapolation of risks from intermediate to low doses were applied. On the basis of current standard practice, the same exposures (milliampere-seconds) were assumed, independent of age.RESULTS. The larger doses and increased lifetime radiation risks in children produce a sharp increase, relative to adults, in estimated risk from CT. Estimated lifetime cancer mortality risks attributable to the radiation exposure from a CT in a 1-year-old are 0.18% (abdominal) and 0.07% (head)—an order of magnitude higher than for adults—although those figures st...
3,023 citations
TL;DR: In contrast to existing lacZ reporter lines, where lacZ expression cannot easily be detected in living tissue, the EYFP and ECFP reporter strains are useful for monitoring the expression of Cre and tracing the lineage of these cells and their descendants in cultured embryos or organs.
Abstract: Background
Several Cre reporter strains of mice have been described, in which a lacZ gene is turned on in cells expressing Cre recombinase, as well as their daughter cells, following Cre-mediated excision of a loxP-flanked transcriptional "stop" sequence. These mice are useful for cell lineage tracing experiments as well as for monitoring the expression of Cre transgenes. The green fluorescent protein (GFP) and variants such as EYFP and ECFP offer an advantage over lacZ as a reporter, in that they can be easily visualized without recourse to the vital substrates required to visualize β-gal in living tissue.
2,941 citations
Book•
01 Jan 2001TL;DR: In recent decades the study of social movements, revolution, democratization and other non-routine politics has flourished as mentioned in this paper, and yet research on the topic remains highly fragmented, reflecting the influence of at least three traditional divisions.
Abstract: In recent decades the study of social movements, revolution, democratization and other non-routine politics has flourished. And yet research on the topic remains highly fragmented, reflecting the influence of at least three traditional divisions. The first of these reflects the view that various forms of contention are distinct and should be studied independent of others. Separate literatures have developed around the study of social movements, revolutions and industrial conflict. A second approach to the study of political contention denies the possibility of general theory in deference to a grounding in the temporal and spatial particulars of any given episode of contention. The study of contentious politics are left to 'area specialists' and/or historians with a thorough knowledge of the time and place in question. Finally, overlaid on these two divisions are stylized theoretical traditions - structuralist, culturalist, and rationalist - that have developed largely in isolation from one another. This book was first published in 2001.
2,809 citations
TL;DR: It is shown that bone marrow from adult humans contains endothelial precursors with phenotypic and functional characteristics of embryonic hemangioblasts, and that these can be used to directly induce new blood vessel formation in the infarct-bed and proliferation of preexisting vasculature after experimental myocardial infarction.
Abstract: Left ventricular remodeling is a major cause of progressive heart failure and death after myocardial infarction. Although neoangiogenesis within the infarcted tissue is an integral component of the remodeling process, the capillary network is unable to support the greater demands of the hypertrophied myocardium, resulting in progressive loss of viable tissue, infarct extension and fibrous replacement. Here we show that bone marrow from adult humans contains endothelial precursors with phenotypic and functional characteristics of embryonic hemangioblasts, and that these can be used to directly induce new blood vessel formation in the infarct-bed (vasculogenesis) and proliferation of preexisting vasculature (angiogenesis) after experimental myocardial infarction. The neoangiogenesis resulted in decreased apoptosis of hypertrophied myocytes in the peri-infarct region, long-term salvage and survival of viable myocardium, reduction in collagen deposition and sustained improvement in cardiac function. The use of cytokine-mobilized autologous human bone-marrow-derived angioblasts for revascularization of infarcted myocardium (alone or in conjunction with currently used therapies) has the potential to significantly reduce morbidity and mortality associated with left ventricular remodeling.
2,688 citations
TL;DR: The previously reported benefits of carvedilol with regard to morbidity and mortality in patients with mild-to-moderate heart failure were also apparent in the patients with severe heart failure who were evaluated in this trial.
Abstract: Background: Beta-blocking agents reduce the risk of hospitalization and death in patients with mild-to-moderate heart failure, but little is known about their effects in severe heart failure.
Methods: We evaluated 2289 patients who had symptoms of heart failure at rest or on minimal exertion, who were clinically euvolemic, and who had an ejection fraction of less than 25 percent. In a double-blind fashion, we randomly assigned 1133 patients to placebo and 1156 patients to treatment with carvedilol for a mean period of 10.4 months, during which standard therapy for heart failure was continued. Patients who required intensive care, had marked fluid retention, or were receiving intravenous vasodilators or positive inotropic drugs were excluded.
Results: There were 190 deaths in the placebo group and 130 deaths in the carvedilol group. This difference reflected a 35 percent decrease in the risk of death with carvedilol (95 percent confidence interval, 19 to 48 percent; P=0.00013, unadjusted; P=0.0014, adjusted for interim analyses). A total of 507 patients died or were hospitalized in the placebo group, as compared with 425 in the carvedilol group. This difference reflected a 24 percent decrease in the combined risk of death or hospitalization with carvedilol (95 percent confidence interval, 13 to 33 percent; P<0.001). The favorable effects on both end points were seen consistently in all the subgroups we examined, including patients with a history of recent or recurrent cardiac decompensation. Fewer patients in the carvedilol group than in the placebo group withdrew because of adverse effects or for other reasons (P=0.02).
Conclusions: The previously reported benefits of carvedilol with regard to morbidity and mortality in patients with mild-to-moderate heart failure were also apparent in the patients with severe heart failure who were evaluated in this trial.
2,566 citations
TL;DR: In this article, the authors used the Jakarta Stock Exchange's reaction to news about former President Suharto's health to assess the value of political connections and found that as much as a quarter of a firm's share price may be accounted for by political connections.
Abstract: While political connections have been widely discussed in the literature on corruption, little work has been done to assess the value of these connections. This paper uses the Jakarta Stock Exchange's reaction to news about former President Suharto's health to address this issue. By examining the difference in share price reactions of firms with varying degrees of political exposure, a market valuation of the proportion of a firm’s value derived from political connections is inferred. The implied value is very high, suggesting that as much as a quarter of a firm’s share price may be accounted for by political connections. (JEL D21, G14)
TL;DR: It is proposed that hSir2, the human homolog of the S. cerevisiae Sir2 protein known to be involved in cell aging and in the response to DNA damage, binds and deacetylates the p53 protein with a specificity for its C-terminal Lys382 residue.
TL;DR: A typology of exploration behaviors is created that finds that the impact of exploration on subsequent technological evolution within the optical disk domain is highest when the exploration spans organizational boundaries but not technological boundaries, and when exploration spans both organizational and technological boundaries.
Abstract: Recognition of the firm's tendency toward local search has given rise to concepts celebrating exploration that overcomes this tendency. To move beyond local search requires that exploration span some boundary, be it organizational or technological. While several studies have encouraged boundary-spanning exploration, few have considered both types of boundaries systematically. In doing so, we create a typology of exploration behaviors: local exploration spans neither boundary, external boundary-spanning exploration spans the firm boundary only, internal boundary-spanning exploration spans the technological boundary only, and radical exploration spans both boundaries. Using this typology, we analyze the impact of knowledge generated by these different types of exploration on subsequent technological evolution.
In our study of patenting activity in optical disk technology, we find that exploration that does not span organizational boundaries consistently generates lower impact on subsequent technological evolution. In addition, we find that the impact of exploration on subsequent technological evolution within the optical disk domain is highest when the exploration spans organizational boundaries but not technological boundaries. At the same time, we find that the impact of exploration on subsequent technological development beyond the optical disk domain is greatest when exploration spans both organizational and technological boundaries. Copyright © 2001 John Wiley & Sons, Ltd.
TL;DR: Collective identity has been treated as an alternative to structurally given interests in accounting for the claims on behalf of which people mobilize, an alternative alternative to selective incentives in understanding why people participate, a alternative to instrumental rationality in explaining what tactical choices activists make, and a complementary alternative to institutional reforms in assessing movements' impacts.
Abstract: ■ Abstract Sociologists have turned to collective identity to fill gaps in resource mobilization and political process accounts of the emergence, trajectories, and impacts of social movements. Collective identity has been treated as an alternative to structurally given interests in accounting for the claims on behalf of which people mobilize, an alternative to selective incentives in understanding why people participate, an alternative to instrumental rationality in explaining what tactical choices activists make, and an alternative to institutional reforms in assessing movements’ impacts. Collective identity has been treated both too broadly and too narrowly, sometimes applied to too many dynamics, at other times made into a residual category within structuralist, state-centered, and rationalist accounts.
TL;DR: It is shown that mammalian Sir2alpha physically interacts with p53 and attenuates p53-mediated functions, and Nicotinamide inhibits an NAD-dependent p53 deacetylation induced by Sir2 alpha, and also enhances the p53 acetylation levels in vivo.
TL;DR: Together, histone acetyltransferases and histone deacetylases determine the acetylation status of histones, and inhibitors of HDACs have been found to cause growth arrest, differentiation and/or apoptosis of many tumours cells by altering the transcription of a small number of genes.
Abstract: Together, histone acetyltransferases and histone deacetylases (HDACs) determine the acetylation status of histones. This acetylation affects the regulation of gene expression, and inhibitors of HDACs have been found to cause growth arrest, differentiation and/or apoptosis of many tumours cells by altering the transcription of a small number of genes. HDAC inhibitors are proving to be an exciting therapeutic approach to cancer, but how do they exert this effect?
TL;DR: The results support the concept that a lineage relationship between neurons and proliferative radial glia may underlie the radial organization of neocortex.
Abstract: The neocortex of the adult brain consists of neurons and glia that are generated by precursor cells of the embryonic ventricular zone. In general, glia are generated after neurons during development, but radial glia are an exception to this rule. Radial glia are generated before neurogenesis and guide neuronal migration. Radial glia are mitotically active throughout neurogenesis, and disappear or become astrocytes when neuronal migration is complete. Although the lineage relationships of cortical neurons and glia have been explored, the clonal relationship of radial glia to other cortical cells remains unknown. It has been suggested that radial glia may be neuronal precursors, but this has not been demonstrated in vivo. We have used a retroviral vector encoding enhanced green fluorescent protein to label precursor cells in vivo and have examined clones 1-3 days later using morphological, immunohistochemical and electrophysiological techniques. Here we show that clones consist of mitotic radial glia and postmitotic neurons, and that neurons migrate along clonally related radial glia. Time-lapse images show that proliferative radial glia generate neurons. Our results support the concept that a lineage relationship between neurons and proliferative radial glia may underlie the radial organization of neocortex.
University of Rochester1, Harvard University2, Johns Hopkins University3, Boston University4, Emory University5, Rutgers University6, University of Kansas7, Rush University Medical Center8, Columbia University9, University of California, San Diego10, University of Michigan11, Wake Forest University12
TL;DR: The limited longitudinal database indicates that the UHDRS may be useful for tracking changes in the clinical features of HD over time and there was an excellent degree of interrater reliability for the motor scores.
Abstract: The Unified Huntington's disease Rating Scale (UHDRS) was developed as a clinical rating scale to assess four domains of clinical performance and capacity in HD: motor function, cognitive function, behavioral abnormalities, and functional capacity. We assessed the internal consistency and the intercorrelations for the four domains and examined changes in ratings over time. We also performed an interrater reliability study of the motor assessment. We found there was a high degree of internal consistency within each of the domains of the UHDRS and that there were significant intercorrelations between the domains of the UHDRS, with the exception of the total behavioral score. There was an excellent degree of interrater reliability for the motor scores. Our limited longitudinal database indicates that the UHDRS may be useful for tracking changes in the clinical features of HD over time. The UHDRS assesses relevant clinical features of HD and appears to be appropriate for repeated administration during clinical studies.
TL;DR: In this article, the authors investigated the dependence of transport costs on geography and infrastructure and found that poor infrastructure is an important determinant of transportation costs, especially for landlocked countries.
Abstract: The authors use different data sets to investigate the dependence of transport costs on geography and infrastructure. Infrastructure is an important determinant of transport costs, especially for landlocked countries. Analysis of bilateral trade data confirms the importance of infrastructure and gives an estimate of the elasticity of trade flows with respect to the trade cost factor of around-3. A deterioration of infrastructure from the median to the 75th percentile raises transport costs by 12 percentage points and reduces trade volumes by 28 percent. Analysis of African trade flows indicates that their relatively low level is largely due to poor infrastructure.
University of Florence1, University of Texas MD Anderson Cancer Center2, University of Turin3, Columbia University4, University of Milan5, University of Parma6, University of Naples Federico II7, University of Pisa8, University of Cambridge9, Sapienza University of Rome10, John Radcliffe Hospital11, University of Michigan12, University of Bologna13, Washington University in St. Louis14, National Institutes of Health15
TL;DR: The specific RET codon mutation correlates with the MEN2 syndromic variant, the age of onset of M TC, and the aggressiveness of MTC; consequently, that mutation should guide major management decisions, such as whether and when to perform thyroidectomy.
Abstract: This is a consensus statement from an international group, mostly of clinical endocrinologists. MEN1 and MEN2 are hereditary cancer syndromes. The commonest tumors secrete PTH or gastrin in MEN1, and calcitonin or catecholamines in MEN2. Management strategies improved after the discoveries of their genes. MEN1 has no clear syndromic variants. Tumor monitoring in MEN1 carriers includes biochemical tests yearly and imaging tests less often. Neck surgery includes subtotal or total parathyroidectomy, parathyroid cryopreservation, and thymectomy. Proton pump inhibitors or somatostatin analogs are the main management for oversecretion of entero-pancreatic hormones, except insulin. The roles for surgery of most entero-pancreatic tumors present several controversies: exclusion of most operations on gastrinomas and indications for surgery on other tumors. Each MEN1 family probably has an inactivating MEN1 germline mutation. Testing for a germline MEN1 mutation gives useful information, but rarely mandates an intervention. The most distinctive MEN2 variants are MEN2A, MEN2B, and familial medullary thyroid cancer (MTC). They vary in aggressiveness of MTC and spectrum of disturbed organs. Mortality in MEN2 is greater from MTC than from pheochromocytoma. Thyroidectomy, during childhood if possible, is the goal in all MEN2 carriers to prevent or cure MTC. Each MEN2 index case probably has an activating germline RET mutation. RET testing has replaced calcitonin testing to diagnose the MEN2 carrier state. The specific RET codon mutation correlates with the MEN2 syndromic variant, the age of onset of MTC, and the aggressiveness of MTC; consequently, that mutation should guide major management decisions, such as whether and when to perform thyroidectomy.
TL;DR: Even after controlling for personal income, education, and occupation, it is found that living in a disadvantaged neighborhood is associated with an increased incidence of coronary heart disease.
Abstract: BACKGROUND: Where a person lives is not usually thought of as an independent predictor of his or her health, although physical and social features of places of residence may affect health and health-related behavior.
METHODS: Using data from the Atherosclerosis Risk in Communities Study, we examined the relation between characteristics of neighborhoods and the incidence of coronary heart disease. Participants were 45 to 64 years of age at base line and were sampled from four study sites in the United States: Forsyth County, North Carolina; Jackson, Mississippi; the northwestern suburbs of Minneapolis; and Washington County, Maryland. As proxies for neighborhoods, we used block groups containing an average of 1000 people, as defined by the U.S. Census. We constructed a summary score for the socioeconomic environment of each neighborhood that included information about wealth and income, education, and occupation.
RESULTS: During a median of 9.1 years of follow-up, 615 coronary events occurred in 13,009 participants. Residents of disadvantaged neighborhoods (those with lower summary scores) had a higher risk of disease than residents of advantaged neighborhoods, even after we controlled for personal income, education, and occupation. Hazard ratios for coronary events in the most disadvantaged group of neighborhoods as compared with the most advantaged group--adjusted for age, study site, and personal socioeconomic indicators--were 1.7 among whites (95 percent confidence interval, 1.3 to 2.3) and 1.4 among blacks (95 percent confidence interval, 0.9 to 2.0). Neighborhood and personal socioeconomic indicators contributed independently to the risk of disease. Hazard ratios for coronary heart disease among low-income persons living in the most disadvantaged neighborhoods, as compared with high-income persons in the most advantaged neighborhoods were 3.1 among whites (95 percent confidence interval, 2.1 to 4.8) and 2.5 among blacks (95 percent confidence interval, 1.4 to 4.5). These associations remained unchanged after adjustment for established risk factors for coronary heart disease.
CONCLUSIONS: Even after controlling for personal income, education, and occupation, we found that living in a disadvantaged neighborhood is associated with an increased incidence of coronary heart disease.
TL;DR: In this article, the authors derived the shear viscosity of the finite-temperature N = 4 supersymmetric Yang-Mills theory in the large N, strong-coupling regime with the absorption cross section of low-energy gravitons by a near-extremal black three-brane.
Abstract: Using the anti–de Sitter/conformal field theory correspondence, we relate the shear viscosity ? of the finite-temperature N = 4 supersymmetric Yang-Mills theory in the large N, strong-coupling regime with the absorption cross section of low-energy gravitons by a near-extremal black three-brane. We show that in the limit of zero frequency this cross section coincides with the area of the horizon. From this result we find ? = ? / 8N2T3. We conjecture that for finite ’t Hooft coupling gYM2N the shear viscosity is ? = f(gYM2N)N2T3, where f(x) is a monotonic function that decreases from O(x-2ln-1(1/x)) at small x to ?/8 when x??.
TL;DR: The past few years have witnessed an explosion of interest in neighborhood or area effects on health as discussed by the authors, and several types of empiric studies have been used to examine possible area or neighborhood effects, including ecologic studies relating area characteristics to morbidity and mortality rates, contextual and multilevel analyses relating area socioeconomic context to health outcomes.
Abstract: The past few years have witnessed an explosion of interest in neighborhood or area effects on health. Several types of empiric studies have been used to examine possible area or neighborhood effects, including ecologic studies relating area characteristics to morbidity and mortality rates, contextual and multilevel analyses relating area socioeconomic context to health outcomes, and studies comparing small numbers of well-defined neighborhoods. Strengthening inferences regarding the presence and magnitude of neighborhood effects will require addressing a series of conceptual and methodological issues. Many of these issues relate to the need to develop theory and specific hypotheses on the processes through which neighborhood and individual factors may jointly influence specific health outcomes. Important challenges include defining neighborhoods or relevant geographic areas, identifying significant area or neighborhood characteristics, specifying the role of individual-level variables, incorporating life-course and longitudinal dimensions, combining a variety of research designs, and avoiding reductionism in the way in which "neighborhood" factors are incorporated into models of disease causation and quantitative analyses.analyses.
TL;DR: By bridging the divides that separate physicians from patients, themselves, colleagues, and society, narrative medicine offers fresh opportunities for respectful, empathic, and nourishing medical care.
Abstract: The effective practice of medicine requires narrative competence, that is, the ability to acknowledge, absorb, interpret, and act on the stories and plights of others. Medicine practiced with narrative competence, called narrative medicine, is proposed as a model for humane and effective medical practice. Adopting methods such as close reading of literature and reflective writing allows narrative medicine to examine and illuminate 4 of medicine's central narrative situations: physician and patient, physician and self, physician and colleagues, and physicians and society. With narrative competence, physicians can reach and join their patients in illness, recognize their own personal journeys through medicine, acknowledge kinship with and duties toward other health care professionals, and inaugurate consequential discourse with the public about health care. By bridging the divides that separate physicians from patients, themselves, colleagues, and society, narrative medicine offers fresh opportunities for respectful, empathic, and nourishing medical care.
TL;DR: In this article, the authors estimate the equity premium from the discount rate that equates market valuations with prevailing expectations of future flows, and find that the average equity premium is around three percent (or less) in the United States and five other markets.
Abstract: The returns earned by U.S. equities since 1926 exceed estimates derived from theory, from other periods and markets, and from surveys of institutional investors. Rather than examine historic experience, we estimate the equity premium from the discount rate that equates market valuations with prevailing expectations of future flows. The accounting flows we project are isomorphic to projected dividends but use more available information and narrow the range of reasonable growth rates. For each year between 1985 and 1998, we find that the equity premium is around three percent (or less) in the United States and five other markets.
TL;DR: In this paper, the authors used previously unexploited data to consider the effects of Bayh-Dole at three leading universities: the University of California, Stanford University, and Columbia University.
TL;DR: This paper is the first and only paper to provide detailed information on the research methodology and sampling strategies employed and a simple description of the baseline non-marital sample from the first seven cities.
TL;DR: Bisulfite genomic sequencing of DNA from oocytes and embryos showed that removal of Dnmt3L prevented methylation of sequences that are normally maternally methylated, and the defect was specific to imprinted regions, and global genome methylation levels were not affected.
Abstract: Complementary sets of genes are epigenetically silenced in male and female gametes in a process termed genomic imprinting. The Dnmt3L gene is expressed during gametogenesis at stages where genomic imprints are established. Targeted disruption of Dnmt3L caused azoospermia in homozygous males, and heterozygous progeny of homozygous females died before midgestation. Bisulfite genomic sequencing of DNA from oocytes and embryos showed that removal of Dnmt3L prevented methylation of sequences that are normally maternally methylated. The defect was specific to imprinted regions, and global genome methylation levels were not affected. Lack of maternal methylation imprints in heterozygous embryos derived from homozygous mutant oocytes caused biallelic expression of genes that are normally expressed only from the allele of paternal origin. The key catalytic motifs characteristic of DNA cytosine methyltransferases have been lost from Dnmt3L, and the protein is more likely to act as a regulator of imprint establishment than as a DNA methyltransferase.
TL;DR: Kang and Stulz as mentioned in this paper pointed out that people tend to invest in the familiar while often ignoring the principles of portfolio theory: people root for the home team, and feel comfortable investing their money in a business that is visible to them.
Abstract: Shareholders of a Regional Bell Operating Company (RBOC) tend to live in the area which it serves, and an RBOC’s customers tend to hold its shares rather than other RBOCs’ equity. The geographic bias of the RBOC investors is closely related to the general tendency of households’ portfolios to be concentrated, of employees’ tendency to own their employers’ stocks in their retirement accounts, and to the home country bias in the international arena. Together, these phenomena provide compeling evidence that people invest in the familiar while often ignoring the principles of portfolio theory. Traditional economic models posit investors who have beliefs about future payoffs of assets. Each investor selects his portfolio so as to maximize the expected utility of the portfolio’s payoff. Investors’ aversion to risk implies that their portfolios should be diversified. In particular, they will greatly benefit from international diversification. Nonetheless, people tend to ignore this advice: by and large, investors’ money stays in their home countries. Kang and Stulz (1997) observe: “Many Financial Economists have noticed that even though the barriers to international investment have fallen dramatically, foreign ownership of shares is still extremely limited and much smaller than one would expect in the absence of barriers to international investment.” An article in the Economist (1996), “Stay-at-Home Shareholders,” concludes: “It appears, therefore, that foreign investment has been hampered, at least until recently, by many of the factors that common sense would suggest: capital controls, opaque markets, and the high cost for fund managers of setting up overseas. In the past few years, these barriers have been falling—especially in emerging markets, where the gains from diversifying are biggest. So investors should soon start gobbling up foreign shares in record numbers. If they do not, economists may have to diversify into other theories.” This article offers a novel explanation of the home country bias: people simply prefer to invest in the familiar. People root for the home team, and feel comfortable investing their money in a business that is visible to them. Paucity of international diversification is only one of the implications of this tendency to invest in the familiar.
TL;DR: There is no evidence that changes in the morphology of spines after LTP are necessary or sufficient for the induction or maintenance of LTP, but a strong correlation between synaptic plasticity and morphological changes in spines is shown.
Abstract: Dendritic spines are morphological specializations that receive synaptic inputs and compartmentalize calcium. In spite of a long history of research, the specific function of spines is still not well understood. Here we review the current status of the relation between morphological changes in spines and synaptic plasticity. Since Cajal and Tanzi proposed that changes in the structure of the brain might occur as a consequence of experience, the search for the morphological correlates of learning has constituted one of the central questions in neuroscience. Although there are scores of studies that encompass this wide field in many species, in this review we focus on experimental work that has analyzed the morphological consequences of hippocampal long-term potentiation (LTP) in rodents. Over the past two decades many studies have demonstrated changes in the morphology of spines after LTP, such as enlargements of the spine head and shortenings of the spine neck. Biophysically, these changes translate into an increase in the synaptic current injected at the spine, as well as shortening of the time constant for calcium compartmentalization. In addition, recent online studies using time-lapse imaging have reported increased spinogenesis. The currently available data show a strong correlation between synaptic plasticity and morphological changes in spines, although at the same time, there is no evidence that these morphological changes are necessary or sufficient for the induction or maintenance of LTP. Still, they highlight once more how form and function go hand in hand in the central nervous system.