Showing papers by "Yale University published in 1994"
TL;DR: Evidence is presented that performance measures can validly characterize older persons across a broad spectrum of lower extremity function and that performance and self-report measures may complement each other in providing useful information about functional status.
Abstract: Background A short battery of physical performance tests was used to assess lower extremity function in more than 5,000 persons age 71 years and older in three communities. Methods Balance, gait, strength, and endurance were evaluated by examining ability to stand with the feet together in the side-by-side, semi-tandem, and tandem positions, time to walk 8 feet, and time to rise from a chair and return to the seated position 5 times. Results A wide distribution of performance was observed for each test. Each test and a summary performance scale, created by summing categorical rankings of performance on each test, were strongly associated with self-report of disability. Both self-report items and performance tests were independent predictors of short-term mortality and nursing home admission in multivariate analyses. However, evidence is presented that the performance tests provide information not available from self-report items. Of particular importance is the finding that in those at the high end of the functional spectrum, who reported almost no disability, the performance test scores distinguished a gradient of risk for mortality and nursing home admission. Additionally, within subgroups with identical self-report profiles, there were systematic differences in physical performance related to age and sex. Conclusion This study provides evidence that performance measures can validly characterize older persons across a broad spectrum of lower extremity function. Performance and self-report measures may complement each other in providing useful information about functional status.
7,417 citations
Thomas Jefferson University1, Harvard University2, Scripps Health3, University of Pittsburgh4, University of British Columbia5, Memorial Hospital of South Bend6, Yale University7, Arizona Heart Institute8, University of Toronto9, St Lukes Episcopal Hospital10, Johns Hopkins University11, Lenox Hill Hospital12, University of Pennsylvania13, University of Texas at San Antonio14, Cleveland Clinic15
TL;DR: In selected patients, placement of an intracoronary stent, as compared with balloon angioplasty, results in an improved rate of procedural success, a lower rate of angiographically detected restenosis, a similar rate of clinical events after six months, and a less frequent need for revascularization of the original coronary lesion.
Abstract: Background Coronary-stent placement is a new technique in which a balloon-expandable, stainless-steel, slotted tube is implanted at the site of a coronary stenosis. The purpose of this study was to compare the effects of stent placement and standard balloon angioplasty on angiographically detected restenosis and clinical outcomes. Methods We randomly assigned 410 patients with symptomatic coronary disease to elective placement of a Palmaz-Schatz stent or to standard balloon angioplasty. Coronary angiography was performed at base line, immediately after the procedure, and six months later. Results The patients who underwent stenting had a higher rate of procedural success than those who underwent standard balloon angioplasty (96.1 percent vs. 89.6 percent, P = 0.011), a larger immediate increase in the diameter of the lumen (1.72 ±0.46 vs. 1.23 ±0.48 mm, P<0.001), and a larger luminal diameter immediately after the procedure (2.49 ±0.43 vs. 1.99 ±0.47 mm, P<0.001). At six months, the patients with stented ...
4,300 citations
TL;DR: System-justification as discussed by the authors is a psychological process that contributes to the preservation of existing social arrangements even at the expense of personal and group interest, and it is argued that the notion of justification is necessary to account for previously unexplained phenomena, such as the participation by disadvantaged individuals and groups in negative stereotypes of themselves, and the consensual nature of stereotypic beliefs despite differences in social relations within and between social groups.
Abstract: Although the concept of justification has played a significant role in many social psychological theories, its presence in recent examinations of stereotyping has been minimal. We describe and evaluate previous notions of stereotyping as ego-justification and group-justification and propose an additional account, that of system-justification, which refers to psychological processes contributing to the preservation of existing social arrangements even at the expense of personal and group interest. It is argued that the notion of system-justification is necessary to account for previously unexplained phenomena, most notably the participation by disadvantaged individuals and groups in negative stereotypes of themselves, and the consensual nature of stereotypic beliefs despite differences in social relations within and between social groups. We offer a selective review of existing research that demonstrates the role of stereotypes in the production of false consciousness and develop the implications of a system-justification approach.
[T]he rationalizing and justifying function of a stereotype exceeds its function as a reflector of group attributes—G. W. Allport (1958, p. 192).
2,615 citations
TL;DR: To evaluate how well quality of life is being measured in the medical literature and to offer a new approach to the measurement, original English-language articles having the term "quality of life" in their titles were identified.
Abstract: Objective. —To evaluate how well quality of life is being measured in the medical literature and to offer a new approach to the measurement. Data Sources. —Original English-language articles having the term "quality of life" in their titles were identified from a recent Quality-of-Life Bibliography and from two MEDLINE searches. Articles were eligible for review only if they described or used one or more "quality-of-life" instruments. Study Selection. —Twenty-five articles were randomly selected from each of the three data sources. Data Extraction. —Each article was reviewed for its compliance with two sets of criteria having several components, which are cited under "Data Synthesis." Data Synthesis. —(1) Investigators conceptually defined quality of life in only 11 (15%) of the 75 articles; identified the targeted domains in only 35 (47%); gave reasons for selecting the chosen quality-of-life instruments in only 27 (36%); and aggregated their results into a composite quality-of-life score in only 27 (38%) of 71 eligible articles. (2) No article distinguished "overall" quality of life from health-related quality of life; patients were invited to give their own separate rating for quality of life in only 13 articles (17%); and among 71 eligible articles, patients were asked to supplement the stipulated items with personal responses in only nine (13%) and to rate the importance of individual items in only six (8.5%). Conclusions. —Because quality of life is a uniquely personal perception, denoting the way that individual patients feel about their health status and/or nonmedical aspects of their lives, most measurements of quality of life in the medical literature seem to aim at the wrong target. Quality of life can be suitably measured only by determining the opinions of patients and by supplementing (or replacing) the instruments developed by "experts." (JAMA. 1994;272:619-626)
2,192 citations
TL;DR: The multiple-risk-factor intervention strategy resulted in a significant reduction in the risk of falling among elderly persons in the community and among persons who had the targeted risk factors for falling, as compared with the control group.
Abstract: Background Since falling is associated with serious morbidity among elderly people, we investigated whether the risk of falling could be reduced by modifying known risk factors. Methods We studied 301 men and women living in the community who were at least 70 years of age and who had at least one of the following risk factors for falling: postural hypotension; use of sedatives; use of at least four prescription medications; and impairment in arm or leg strength or range of motion, balance, ability to move safely from bed to chair or to the bathtub or toilet (transfer skills), or gait. These subjects were given either a combination of adjustment in their medications, behavioral instructions, and exercise programs aimed at modifying their risk factors (intervention group, 153 subjects) or usual health care plus social visits (control group, 148 subjects). Results During one year of follow-up, 35 percent of the intervention group fell, as compared with 47 percent of the control group (P = 0.04). The adjusted...
2,128 citations
TL;DR: It is reported that a human gene encoding a protein, hMLHl (human MutL homologue), homologous to the bacterial DNA mismatch repair protein MutL, is located on human chromosome 3p21.3-23.
Abstract: The human DNA mismatch repair gene homologue hMSH2, on chromosome 2p is involved in hereditary non-polyposis colon cancer (HNPCC) On the basis of linkage data, a second HNPCC locus was assigned to chromosome 3p21-23 (ref 3) Here we report that a human gene encoding a protein, hMLH1 (human MutL homologue), homologous to the bacterial DNA mismatch repair protein MutL, is located on human chromosome 3p213-23 We propose that hMLH1 is the HNPCC gene located on 3p because of the similarity of the hMLH1 gene product to the yeast DNA mismatch repair protein, MLH1, the coincident location of the hMLH1 gene and the HNPCC locus on chromosome 3, and hMLH1 missense mutations in affected individuals from a chromosome 3-linked HNPCC family
2,081 citations
TL;DR: Males were found to be more assertive and had slightly higher self-esteem than females and females were higher than males in extraversion, anxiety, trust, and, especially, tender-mindedness.
Abstract: Four meta-analyses were conducted to examine gender differences in personality in the literature (1958-1992) and in normative data for well-known personality inventories (1940-1992). Males were found to be more assertive and had slightly higher self-esteem than females. Females were higher than males in extraversion, anxiety, trust, and, especially, tender-mindedness (e.g., nurturance). There were no noteworthy sex differences in social anxiety, impulsiveness, activity, ideas (e.g., reflectiveness), locus of control, and orderliness. Gender differences in personality traits were generally constant across ages, years of data collection, educational levels, and nations.
2,026 citations
TL;DR: It is shown that polymorphic microsatellites (primarily CA repeats) allow trees of human individuals to be constructed that reflect their geographic origin with remarkable accuracy by the analysis of a large number of loci for each individual, in spite of the small variations in allele frequencies existing between populations.
Abstract: Genetic variation at hypervariable loci is being used extensively for linkage analysis and individual identification, and may be useful for inter-population studies. Here we show that polymorphic microsatellites (primarily CA repeats) allow trees of human individuals to be constructed that reflect their geographic origin with remarkable accuracy. This is achieved by the analysis of a large number of loci for each individual, in spite of the small variations in allele frequencies existing between populations. Reliable evolutionary relationships could also be established in comparisons among human populations but not among great ape species, probably because of constraints on allele length variation. Among human populations, diversity of microsatellites is highest in Africa, which is in contrast to other nuclear markers and supports the hypothesis of an African origin for humans.
1,804 citations
TL;DR: A protective effect of the ε2 allele, in addition to the dose effect ofThe ε4 allele in sporadic AD, is demonstrated, which further support the direct involvement of APOE in the pathogenesis of AD.
Abstract: Gene dosage of the apolipoprotein E (APOE) epsilon 4 allele is a major risk factor for familial Alzheimer disease (AD) of late onset (after age 60). Here we studied a large series of 115 AD case subjects and 243 controls as well as 150 affected and 197 unaffected members of 66 AD families. Our data demonstrate a protective effect of the epsilon 2 allele, in addition to the dose effect of the epsilon 4 allele in sporadic AD. Although a substantial proportion (65%) of AD is attributable to the presence of epsilon 4 alleles, risk of AD is lowest in subjects with the epsilon 2/epsilon 3 genotype, with an additional 23% of AD attributable to the absence of an epsilon 2 allele. The opposite actions of the epsilon 2 and epsilon 4 alleles further support the direct involvement of APOE in the pathogenesis of AD.
1,797 citations
TL;DR: The anti-inflammatory drugs sodium salicylate and aspirin inhibited the activation of NF-kappa B, which further explains the mechanism of action of these drugs.
Abstract: The transcription factor nuclear factor-kappa B (NF-kappa B) is critical for the inducible expression of multiple cellular and viral genes involved in inflammation and infection including interleukin-1 (IL-1), IL-6, and adhesion molecules. The anti-inflammatory drugs sodium salicylate and aspirin inhibited the activation of NF-kappa B, which further explains the mechanism of action of these drugs. This inhibition prevented the degradation of the NF-kappa B inhibitor, I kappa B, and therefore NF-kappa B was retained in the cytosol. Sodium salicylate and aspirin also inhibited NF-kappa B-dependent transcription from the Ig kappa enhancer and the human immunodeficiency virus (HIV) long terminal repeat (LTR) in transfected T cells.
1,771 citations
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TL;DR: This paper examined the investment strategies of 155 mutual funds over the 1975-84 period to determine the extent to which the funds purchased stocks based on their past returns, and determine the relation of this behavior to their observed portfolio performance.
Abstract: We examine the investment strategies of 155 mutual funds over the 1975-84 period to determine the extent to which the funds purchased stocks based on their past returns, and to determine the relation of this behavior to their observed portfolio performance We find that about 77% of these mutual funds were "momentum investors", buying stocks that were past winners; however, they did not systematically sell past losers On average, these "trend-followers" realized significantly better performance than the remaining funds We also find that the mutual funds exhibited herding behavior, and that the tendency of a fund to herd in its trades was strongly correlated with its tendency to buy past winners as well as with its portfolio performance Consistent with the evidence on trend-following, herding into past winners was stronger than herding into past losers
TL;DR: Skin appears to possess a p53-dependent 'guardian-of-the-tissue' response to DNA damage which aborts precancerous cells, and if this response is reduced in a single cell by a prior p53 mutation, sunburn can select for clonal expansion of the p 53-mutated cell into the AK.
Abstract: Squamous cell carcinoma of the skin (SCC) can progress by stages: sun-damaged epidermis, with individual disordered keratinocytes; actinic keratosis (AK), spontaneously regressing keratinized patches having aberrant cell differentiation and proliferation; carcinoma in situ; SCC and metastasis. To understand how sunlight acts as a carcinogen, we determined the stage at which sunlight mutates the p53 tumour-suppressor gene and identified a function for p53 in skin. The p53 mutations induced by ultraviolet radiation and found in > 90% of human SCCs were present in AKs. Inactivating p53 in mouse skin reduced the appearance of sunburn cells, apoptotic keratinocytes generated by overexposure to ultraviolet. Skin thus appears to possess a p53-dependent 'guardian-of-the-tissue' response to DNA damage which aborts precancerous cells. If this response is reduced in a single cell by a prior p53 mutation, sunburn can select for clonal expansion of the p53-mutated cell into the AK. Sunlight can act twice: as tumour initiator and tumour promoter.
TL;DR: In this article, the authors show how broadening systemic theory beyond rationalist concerns can help it to explain structural change in world politics and how collective identity among states could emerge endogenously at the systemic level.
Abstract: The neorealist-neoliberal debate about the possibilities for collective action in international relations has been based on a shared commitment to Mancur Olson's rationalist definition of the problem as one of getting exogenously given egoists to cooperate. Treating this assumption as a de facto hypothesis about world politics, I articulate the rival claim that interaction at the systemic level changes state identities and interests. The causes of state egoism do not justify always treating it as given. Insights from critical international relations and integration theories suggest how collective identity among states could emerge endogenously at the systemic level. Such a process would generate cooperation that neither neorealists nor neoliberals expect and help transform systemic anarchy into an “international state”—a transnational structure of political authority that might undermine territorial democracy. I show how broadening systemic theory beyond rationalist concerns can help it to explain structural change in world politics.
TL;DR: The crystal structure of Escherichia coli GroEL shows a porous cylinder of 14 subunits made of two nearly 7-fold rotationally symmetrical rings stacked back-to-back with dyad symmetry.
Abstract: The crystal structure of Escherichia coli GroEL shows a porous cylinder of 14 subunits made of two nearly 7-fold rotationally symmetrical rings stacked back-to-back with dyad symmetry. The subunits consist of three domains: a large equatorial domain that forms the foundation of the assembly at its waist and holds the rings together; a large loosely structured apical domain that forms the ends of the cylinder; and a small slender intermediate domain that connects the two, creating side windows. The three-dimensional structure places most of the mutationally defined functional sites on the channel walls and its outward invaginations, and at the ends of the cylinder.
TL;DR: The findings suggest that at younger ages, death from coronary heart disease is influenced by genetic factors in both women and men, and implies that the genetic effect decreases at older ages.
Abstract: Background A family history of premature coronary heart disease has long been thought to be a risk factor for coronary heart disease. Using data from 26 years of follow-up of 21,004 Swedish twins born between 1886 and 1925, we investigated this issue further by assessing the risk of death from coronary heart disease in pairs of monozygotic and dizygotic twins. Methods The study population consisted of 3298 monozygotic and 5964 dizygotic male twins and 4012 monozygotic and 7730 dizygotic female twins. The age at which one twin died of coronary heart disease was used as the primary independent variable to predict the risk of death from coronary heart disease in the other twin. Information about other risk factors was obtained from questionnaires administered in 1961 and 1963. Actuarial life-table analysis was used to estimate the cumulative probability of death from coronary heart disease. Relative-hazard estimates were obtained from a multivariate survival analysis. Results Among the men, the relative haza...
TL;DR: It is found that an AAV vector containing the LacZ gene resulted in expression of β-galactosidase up to three months post-injection in vivo, and safe and stable TH gene transfer into the denervated striatum may have potential for the genetic therapy of Parkinson's disease.
Abstract: Adeno-associated viral (AAV) vectors are non-pathogenic, integrating DNA vectors in which all viral genes are removed and helper virus is completely eliminated. To evaluate this system in the post-mitotic cells of the brain, we found that an AAV vector containing the lacZ gene (AAVlac) resulted in expression of beta-galactosidase up to three months post-injection in vivo. A second vector expressing human tyrosine hydroxylase (AAVth) was injected into the denervated striatum of unilateral 6-hydroxydopamine-lesioned rats. Tyrosine hydroxylase (TH) immunoreactivity was detectable in striatal neurons and glia for up to four months and we also found significant behavioural recovery in lesioned rats treated with AAVth versus AAVlac controls. Safe and stable TH gene transfer into the denervated striatum may have potential for the genetic therapy of Parkinson's disease.
TL;DR: It is demonstrated that Liddle's syndrome is caused by mutations in the beta subunit of the epithelial sodium channel and have implications for the regulation of this epithelial ion channel as well as blood pressure homeostasis.
TL;DR: A computerized 3-dimensional volume array modeling all major internal structures of the body has been created and can serve as a voxel-based anthropomorphic phantom suitable for many computer-based modeling and simulation calculations.
Abstract: Manual segmentation of 129 x-ray CT transverse slices of a living male human has been done and a computerized 3-dimensional volume array modeling all major internal structures of the body has been created. Each voxel of the volume contains a index number designating it as belonging to a given organ or internal structure. The original x-ray CT images were reconstructed in a 512×512 matrix with a resolution of 1 mm in the x,y plane. The z-axis resolution is 1 cm from neck to midthigh and 0.5 cm from neck to crown of the head. This volume array represents a high resolution model of the human anatomy and can serve as a voxel-based anthropomorphic phantom suitable for many computer-based modeling and simulation calculations.
TL;DR: In this article, a ramped-amplitude cross-polarization sequence (RAMP-CP) was proposed for the Hartmann-Hahn matching profile in CP-MAS NMR.
TL;DR: Heterotypic adhesive interactions between epithelial cells and intraepithelial lymphocytes in vitro are mediated by E-cadherin and the αEβ7 integrin, and are shown to mediated the tissue-specific compartmentalization of lymphocytes.
Abstract: IN contrast to sessile cell types, lymphocytes migrate through the vasculature to become diffusely distributed in tissues or organized in lymphoid structures. A complex array of adhesion molecules including selectins, integrins and their counter-receptors mediate lymphocyte homing and migration into tissues and may be constitutively expressed or induced1,2. However, the molecules that mediate the tissue-specific retention of lymphocytes within the parenchyma have not been identified. Along the epithelium at the basolateral surface of enterocytes, intestinal intraepithelial lymphocytes are found. These T cells of the mucosal immune system serve as a model for the tissue-specific compartmentalization of lymphocytes. We investigated whether the localization of these intestinal intra-epithelial lymphocytes could be mediated by specific interactions between adhesion molecules expressed selectively on this subpopu-lation of T cells and tissue-restricted adhesion molecules on epi-thelial cells. Here we show that heterotypic adhesive interactions between epithelial cells and intraepithelial lymphocytes in vitro are mediated by E-cadherin and the αEβ7 integrin.
TL;DR: The strong independent association between self-efficacy and function found in this study suggests that clinical programs in areas such as prevention, geriatric evaluation and management, and rehabilitation should attempt simultaneously to improve physical skills and confidence.
Abstract: BACKGROUND: The relationships of fear of falling and fall-related efficacy with measures of basic and instrumental activities of daily living (ADL-IADL) and physical and social functioning were evaluated in a cohort of community-living elderly persons. METHODS: Sociodemographic, medical, psychological, and physical performance (e.g., gait speed, timed hand function) measures were administered, during an in-home assessment, to a probability sample of 1,103 residents of New Haven, Connecticut, who were > or = 72 years of age. Falls and injuries in the past year, fear of falling, and responses to the Falls Efficacy Scale were also ascertained. The three dependent variables included a 10-item ADL-IADL scale, an 8-item social activity scale, and a scale of relative physical activity level. RESULTS: Among cohort members, 57% denied fear of falling whereas 24% acknowledged fear but denied effect on activity; 19% acknowledged avoiding activities because of fear of falling. Twenty-four percent of recent fallers vs 15% of nonfallers acknowledged this activity restriction (chi 2 = 13.1; p < .001). Mean fall-related efficacy score among the cohort was 84.9 (SD 20.5), 79.8 (SD 23.4), and 88.1 (SD 17.9) among fallers and nonfallers, respectively (p < or = .0001). Fall-related efficacy proved a potent independent correlate of ADL-IADL (partial correlation = .265, p < .001); physical (partial correlation = .234, p < .001); and social (partial correlation = .088, p < .01), functioning in multiple regression models after adjusting for sociodemographic, medical, psychological, and physical performance covariates as well as history of recent falls and injuries. Fear of falling was only marginally related (p = .05) with ADL-IADL functioning and was not associated with higher level physical or social functioning. CONCLUSIONS: The strong independent association between self-efficacy and function found in this study suggests that clinical programs in areas such as prevention, geriatric evaluation and management, and rehabilitation should attempt simultaneously to improve physical skills and confidence. Available knowledge of the factors influencing efficacy should guide the development of these efficacy-building programs.
TL;DR: Research in animals and of cognitive function in normal, brain-injured, and schizophrenic subjects support the theory that a defect in working memory--the ability to guide behavior by representations--may be the fundamental impairment leading to schizophrenic thought disorder.
Abstract: Recent advances in anatomical, behavioral, and physiological techniques have produced new information about the nature of prefrontal function, its cellular basis, and its anatomical underpinnings in nonhuman primates. These findings are changing our views of prefrontal function and providing insight into possible bases for human mental disorder. A major advance is the recognition that various prefrontal areas are engaged in holding information "on line" and updating past and current information on a moment-to-moment basis. Studies of animals and of cognitive function in normal, brain-injured, and schizophrenic subjects support the theory that a defect in working memory--the ability to guide behavior by representations--may be the fundamental impairment leading to schizophrenic thought disorder.
TL;DR: Investigating whether one of the mechanisms by which glucocorticoids exert their antiinflammatory activities is through inhibition of gene activation mediated by NF-kappa B suggests that direct interactions between NF- kappa B and glucoc Corticoid receptor may partly account for the antiinflammatory properties of glucocORTicoids in vivo.
Abstract: Glucocorticoids, which are widely used as antiinflammatory agents, downregulate the expression of the interleukin 6 gene and of additional cytokine genes involved in inflammatory responses. Conversely, the transcription factor NF-kappa B, a member of the Rel family of transcription factors, has been implicated in the induction of multiple genes involved in the early processes of immune and inflammatory responses. This prompted us to investigate whether one of the mechanisms by which glucocorticoids exert their antiinflammatory activities is through inhibition of gene activation mediated by NF-kappa B. We report that, in intact cells, activation of the interleukin 6 promoter by a combination of the factor NF-IL6 and the p65 subunit of NF-kappa B is inhibited by dexamethasone (ligand)-activated glucocorticoid receptor. Conversely, activation of the mouse mammary tumor virus promoter by a combination of dexamethasone and glucocorticoid receptor is inhibited by overexpression of p65. Furthermore, we provide evidence for physical association between glucocorticoid receptor and p65 in protein crosslinking and coimmunoprecipitation experiments, using either in vitro translated proteins or those present in cell extracts. These studies suggest that direct interactions between NF-kappa B and glucocorticoid receptor may partly account for the antiinflammatory properties of glucocorticoids in vivo.
TL;DR: In this article, the stability or lack thereof of nonrelativistic fermionic systems to interactions is studied within the renormalization-group (RG) framework, in close analogy with the study of critical phenomena using ${ensuremath{\varphi}}^{4}$ scalar field theory.
Abstract: The stability or lack thereof of nonrelativistic fermionic systems to interactions is studied within the renormalization-group (RG) framework, in close analogy with the study of critical phenomena using ${\ensuremath{\varphi}}^{4}$ scalar field theory. A brief introduction to ${\ensuremath{\varphi}}^{4}$ theory in four dimensions and the path-integral formulation for fermions is given before turning to the problem at hand. As for the latter, the following procedure is used. First, the modes on either side of the Fermi surface within a cutoff $\ensuremath{\Lambda}$ are chosen for study, in analogy with the modes near the origin in ${\ensuremath{\varphi}}^{4}$ theory, and a path integral is written to describe them. Next, an RG transformation that eliminates a part of these modes, but preserves the action of the noninteracting system, is identified. Finally the possible perturbations of this free-field fixed point are classified as relevant, irrelevant or marginal. A $d=1$ warmup calculation involving a system of fermions shows how, in contrast to mean-field theory, which predicts a charge-density wave for arbitrarily weak repulsion, and superconductivity for arbitrarily weak attraction, the renormalization-group approach correctly yields a scale-invariant system (Luttinger liquid) by taking into account both instabilities. Application of the renormalization group in $d=2 \mathrm{and} 3$, for rotationally invariant Fermi surfaces, automatically leads to Landau's Fermi-liquid theory, which appears as a fixed point characterized by an effective mass and a Landau function $F$, with the only relevant perturbations being of the superconducting (BCS) type. The functional flow equations for the BCS couplings are derived and separated into an infinite number of flows, one for each angular momentum. It is shown that similar results hold for rotationally noninvariant (but time-reversal-invariant) Fermi surfaces also, with obvious loss of rotational invariance in the parametrization of the fixed-point interactions. A study of a nested Fermi surface shows an additional relevant flow leading to charge-density-wave formation. It is pointed out that, for small $\frac{\ensuremath{\Lambda}}{{K}_{F}}$, a $\frac{1}{N}$ expansion emerges, with $N=\frac{{K}_{F}}{\ensuremath{\Lambda}}$, which explains why one is able to solve the narrow-cutoff theory. The search for non-Fermi liquids in $d=2$ using the RG is discussed. Bringing a variety of phenomena (Landau theory, charge-density waves, BCS instability, nesting, etc.) under the one unifying principle of the RG not only allows us to better understand and unify them, but also paves the way for generalizations and extensions. The article is pedagogical in nature and is expected to be accessible to any serious graduate student. On the other hand, its survey of the vast literature is mostly limited to the RG approach.
TL;DR: Mice rendered deficient in lymphotoxin by gene targeting in embryonic stem cells have no morphologically detectable lymph nodes or Peyer's patches, although development of the thymus appears normal, and data suggest an essential role for LT in the normal development of peripheral lymphoid organs.
Abstract: Mice rendered deficient in lymphotoxin (LT) by gene targeting in embryonic stem cells have no morphologically detectable lymph nodes or Peyer's patches, although development of the thymus appears normal. Within the white pulp of the spleen, there is failure of normal segregation of B and T cells. Spleen and peripheral blood contain CD4+CD8- and CD4-CD8+ T cells in a normal ratio, and both T cells subsets have an apparently normal lytic function. Lymphocytes positive for immunoglobulin M are present in increased numbers in both the spleen and peripheral blood. These data suggest an essential role for LT in the normal development of peripheral lymphoid organs.
TL;DR: Lisitsyn et al. as discussed by the authors adapted representational difference analysis (RDA) for use with cDNA, which was found to be extremely sensitive, reproducible, and predominantly lacked false positives.
Abstract: Detection of differentially regulated genes has been severely hampered by technical limitations. In an effort to overcome these problems, the PCR-coupled subtractive process of representational difference analysis (RDA) [Lisitsyn, N. et al. (1993) Science 259, 946-951] has been adapted for use with cDNA. In a model system, RAG-1 and RAG-2, the genes responsible for activating V(D)J recombination, were identified in a genomic transfectant by cDNA RDA in a small fraction of the time taken by conventional means. The system was also modified to eliminate expected difference products to facilitate the identification of novel genes. Additional alterations to the conditions allowed isolation of differentially expressed fragments. Several caffeine up-regulated clones were obtained from the pre-B cell line 1-8, including IGF-1B, and a predicted homologue of the natural killer cell antigen, NKR-P1. The approach was found to be fast, extremely sensitive, reproducible, and predominantly lacked false positives. cDNA RDA has the capacity and adaptability to be applied to a wide range of biological problems, including the study of single gene disorders, characterization of mutant and complemented cell types, developmental or post-event expression time courses, and examination of pathogen-host interactions.
TL;DR: In this paper, a representative agent model with money holdings motivated by transactions costs, a fiscal authority that taxes and issues debt, no production, and a convenient functional form for agents' utility is presented.
Abstract: A representative-agent model with money holdings motivated by transactions costs, a fiscal authority that taxes and issues debt, no production, and a convenient functional form for agents' utility is presented. The model can be solved analytically, and illustrates the dependence of price determination on fiscal policy, the possibility of indeterminacy, even stochastic explosion, of the price level in the face of a monetary policy that holdsM fixed, and the possibility of a unique, stable price level in the face of a monetary policy that simply pegs the nominal interest rate at an arbitrary level. In a rational expectations, market-clearing equilibrium model with a costlessly-produced fiat money that is useful in transactions, the following things are true under broad assumptions. - A monetary policy that fixes the money stock may (depending on the transactions technology) be consistent with indeterminacy of the price level—indeed with stochastically fluctuating, explosive inflation. - A monetary policy that fixes the nominal interest rate, even if it holds the interest rate constant regardless of the observed rate of inflation or money growth rate, may deliver a uniquely determined price level. - The existence and uniqueness of the equilibrium price level cannot be determined from knowledge of monetary policy alone; fiscal policy plays an equally important role. Special case models with interest-bearing debt and no money are possible, just as are special cases with money and no interest-bearing debt. In each the price level may be uniquely determined. Determinacy of the price level under any policy depends on the public's beliefs about what the policy authority would do under conditions that are never observed in equilibrium. These points are not new. Eric Leeper [1991] has made most of them within a single coherent model. Woodford [1993], in a representative agent cash-in-advance model, has displayed the possibility of indeterminacy with a fixed quantity of money and the possibility of uniqueness with an interest-rate pegging policy. Aiyagari and Gertler [1985] use an overlapping generations model to make many of the points made in this paper, without discussing the possibility of stochastic sunspot equilibria. Sargent and Wallace [1981] and Obstfeld [1983] have also discussed related issues. This paper improves on Leeper by moving beyond his analysis of local linear approximations to the full model solution, as is essential if explosive sunspot equilibria are to be distinguished from explosive solutions to the Euler equations that can be ruled out as equilibria. It improves on the other cited work by pulling together into the context of one fairly transparent model discussion of phenomena previously discussed in isolation in very different models. We study a representative agent model in which there is no production or real savings, but transactions costs generate a demand for money. The government costlessly provides fiat money balances, imposes lump-sum taxes, and issues debt, but has no other role in the economy. We make restrictive assumptions about the form of the utility function and the form of a transactions cost term in the budget constraint. The model could be extended to include production, capital accumulation, non-neutral taxation, productive government expenditure, and a more general utility function without affecting the conclusions discussed in this paper. Indeed the model I informally matched to data in an earlier paper [1988] makes some such extensions. While such an extended model is more realistic, it is harder to solve. The version in my earlier paper [1988] was solved numerically and simulated. The bare-bones model of this paper allows an explicit analytic solution that may make its results easier to understand.
01 Jan 1994
TL;DR: Green and Shapiro as discussed by the authors assess rational choice theory where it is reputed to be most successful: the study of collective action, the behavior of political parties and politicians, and such phenomena as voting cycles and Prisoner's dilemma.
Abstract: This is the first comprehensive critical evaluation of the use of rational choice theory in political science. Writing in an accessible and nontechnical style, Donald P. Green and Ian Shapiro assess rational choice theory where it is reputed to be most successful: the study of collective action, the behavior of political parties and politicians, and such phenomena as voting cycles and Prisoner's Dilemmas. In their hard-hitting critique, Green and Shapiro demonstrate that the much heralded achievements of rational choice theory are in fact deeply suspect and that fundamental rethinking is needed if rational choice theorists are to contribute to the understanding of politics. In their final chapters, they anticipate and respond to a variety of possible rational choice responses to their arguments, thereby initiating a dialogue that is bound to continue for some time.
TL;DR: A large number of women with a family history of breast cancer face the task of providing appropriate screening schedules for their patients, and one group for whom this is particularly important are those Women with aFamily history of Breast cancer.
Abstract: Background. Improvements in screening techniques have made significant contributions to the early detection of breast cancer. Physicians thus face the task of providing appropriate screening schedules for their patients. One group for whom this is particularly important are those women with a family history of breast cancer.
Methods. In this report, data from the Cancer and Steroid Hormone Study, a population-based, case-control study conducted by the Centers for Disease Control, are used to provide age-specific risk estimates of breast cancer for women with a family history of breast cancer. The data set includes 4730 patients with histologically confirmed breast cancer age 20–54 years and 4688 control subjects who were frequency matched to patients by geographic region and 5-year age intervals. The data set also includes family histories of breast cancer in mothers and sisters of both patients and control subjects.
Results. Genetic models fit previously to these data by the authors have provided evidence for a rare autosomal dominant allele that results in increased susceptibility to breast cancer. In addition, these models predict that women who carry the allele are at greater risk of developing breast cancer at any age than are women who do not carry the allele. The increase in risk in carriers versus noncarriers does, however, decrease with increasing age. Based on the parameters of this model, age-specific risks for a woman with one or more relatives affected with breast cancer at various ages at onset are given.
Conclusions. These tables can be used for the purpose of counseling women at high risk of breast cancer development, that is, women with a family history of breast cancer.