Showing papers by "Northwestern University published in 1999"

A finite element method for crack growth without remeshing

Abstract: SUMMARY An improvement of a new technique for modelling cracks in the nite element framework is presented. A standard displacement-based approximation is enriched near a crack by incorporating both discontinuous elds and the near tip asymptotic elds through a partition of unity method. A methodology that constructs the enriched approximation from the interaction of the crack geometry with the mesh is developed. This technique allows the entire crack to be represented independently of the mesh, and so remeshing is not necessary to model crack growth. Numerical experiments are provided to demonstrate the utility and robustness of the proposed technique. Copyright ? 1999 John Wiley & Sons, Ltd.

Elastic crack growth in finite elements with minimal remeshing

Abstract: A minimal remeshing finite element method for crack growth is presented. Discontinuous enrichment functions are added to the finite element approximation to account for the presence of the crack. This method allows the crack to be arbitrarily aligned within the mesh. For severely curved cracks, remeshing may be needed but only away from the crack tip where remeshing is much easier. Results are presented for a wide range of two-dimensional crack problems showing excellent accuracy. Copyright © 1999 John Wiley & Sons, Ltd.

Keap1 represses nuclear activation of antioxidant responsive elements by Nrf2 through binding to the amino-terminal Neh2 domain

Abstract: Transcription factor Nrf2 is essential for the antioxidant responsive element (ARE)-mediated induction of phase II detoxifying and oxidative stress enzyme genes. Detailed analysis of differential Nrf2 activity displayed in transfected cell lines ultimately led to the identification of a new protein, which we named Keap1, that suppresses Nrf2 transcriptional activity by specific binding to its evolutionarily conserved amino-terminal regulatory domain. The closest homolog of Keap1 is a Drosophila actin-binding protein called Kelch, implying that Keap1 might be a Nrf2 cytoplasmic effector. We then showed that electrophilic agents antagonize Keap1 inhibition of Nrf2 activity in vivo, allowing Nrf2 to traverse from the cytoplasm to the nucleus and potentiate the ARE response. We postulate that Keap1 and Nrf2 constitute a crucial cellular sensor for oxidative stress, and together mediate a key step in the signaling pathway that leads to transcriptional activation by this novel Nrf2 nuclear shuttling mechanism. The activation of Nrf2 leads in turn to the induction of phase II enzyme and antioxidative stress genes in response to electrophiles and reactive oxygen species.

"Dip-Pen" Nanolithography

Abstract: A direct-write “dip-pen” nanolithography (DPN) has been developed to deliver collections of molecules in a positive printing mode. An atomic force microscope (AFM) tip is used to write alkanethiols with 30-nanometer linewidth resolution on a gold thin film in a manner analogous to that of a dip pen. Molecules are delivered from the AFM tip to a solid substrate of interest via capillary transport, making DPN a potentially useful tool for creating and functionalizing nanoscale devices.

Network location and learning: the influence of network resources and firm capabilities on alliance formation

Abstract: This paper presents a dynamic, firm-level study of the role of network resources in determining alliance formation. Such resources inhere not so much within the firm but reside in the interfirm networks in which firms are placed. Data from extensive fieldwork show that by influencing the extent to which firms have access to information about potential partners, such resources are an important catalyst for new alliances, especially because alliances entail considerable hazards. This study also assesses the importance of firms’ capabilities with alliance formation and material resources as determinants of their alliance decisions. I test this dynamic framework and its hypotheses about the role of time-varying network resources and firm capabilities with comprehensive longitudinal multi-industry data on the formation of strategic alliances by a panel of firms between 1970 and 1989. The results confirm field observations that accumulated network resources arising from firm participation in the network of accumulated prior alliances are influential in firms’ decisions to enter into new alliances. This study highlights the importance of network resources that firms derive from their embeddedness in networks for explaining their strategic behavior. Copyright © 1999 John Wiley & Sons, Ltd.

Relationship of MRI delayed contrast enhancement to irreversible injury, infarct age, and contractile function.

Abstract: Background—Contrast MRI enhancement patterns in several pathophysiologies resulting from ischemic myocardial injury are controversial or have not been investigated. We compared contrast enhancement in acute infarction (AI), after severe but reversible ischemic injury (RII), and in chronic infarction. Methods and Results—In dogs, a large coronary artery was occluded to study AI and/or chronic infarction (n=18), and a second coronary artery was chronically instrumented with a reversible hydraulic occluder and Doppler flowmeter to study RII (n=8). At 3 days after surgery, cine MRI revealed reduced wall thickening in AI (5±6% versus 33±6% in normal, P<0.001). In RII, wall thickening before, during, and after inflation of the occluder for 15 minutes was 35±5%, 1±8%, and 21±10% and Doppler flow was 19.8±5.3, 0.2±0.5, and 56.3±17.7 (peak hyperemia) cm/s, respectively, confirming occlusion, transient ischemia, and reperfusion. Gd-DTPA–enhanced MR images acquired 30 minutes after contrast revealed hyperenhancement...

The Effect of Raloxifene on Risk of Breast Cancer in Postmenopausal Women: Results From the MORE Randomized Trial

Abstract: ContextRaloxifene hydrochloride is a selective estrogen receptor modulator that has antiestrogenic effects on breast and endometrial tissue and estrogenic effects on bone, lipid metabolism, and blood clotting.ObjectiveTo determine whether women taking raloxifene have a lower risk of invasive breast cancer.Design and SettingThe Multiple Outcomes of Raloxifene Evaluation (MORE), a multicenter, randomized, double-blind trial, in which women taking raloxifene or placebo were followed up for a median of 40 months (SD, 3 years), from 1994 through 1998, at 180 clinical centers composed of community settings and medical practices in 25 countries, mainly in the United States and Europe.ParticipantsA total of 7705 postmenopausal women, younger than 81 (mean age, 66.5) years, with osteoporosis, defined by the presence of vertebral fractures or a femoral neck or spine T-score of at least 2.5 SDs below the mean for young healthy women. Almost all participants (96%) were white. Women who had a history of breast cancer or who were taking estrogen were excluded.InterventionRaloxifene, 60 mg, 2 tablets daily; or raloxifene, 60 mg, 1 tablet daily and 1 placebo tablet; or 2 placebo tablets.Main Outcome MeasuresNew cases of breast cancer, confirmed by histopathology. Transvaginal ultrasonography was used to assess the endometrial effects of raloxifene in 1781 women. Deep vein thrombosis or pulmonary embolism were determined by chart review.ResultsThirteen cases of breast cancer were confirmed among the 5129 women assigned to raloxifene vs 27 among the 2576 women assigned to placebo (relative risk [RR], 0.24; 95% confidence interval [CI], 0.13-0.44; P<.001). To prevent 1 case of breast cancer, 126 women would need to be treated. Raloxifene decreased the risk of estrogen receptor–positive breast cancer by 90% (RR, 0.10; 95% CI, 0.04-0.24), but not estrogen receptor–negative invasive breast cancer (RR, 0.88; 95% CI, 0.26-3.0). Raloxifene increased the risk of venous thromboembolic disease (RR, 3.1; 95% CI, 1.5-6.2), but did not increase the risk of endometrial cancer (RR, 0.8; 95% CI, 0.2-2.7).ConclusionAmong postmenopausal women with osteoporosis, the risk of invasive breast cancer was decreased by 76% during 3 years of treatment with raloxifene.

Undetectable intracellular free copper: the requirement of a copper chaperone for superoxide dismutase.

Abstract: The copper chaperone for the superoxide dismutase (CCS) gene is necessary for expression of an active, copper-bound form of superoxide dismutase (SOD1) in vivo in spite of the high affinity of SOD1 for copper (dissociation constant = 6 fM) and the high intracellular concentrations of both SOD1 (10 μM in yeast) and copper (70 μM in yeast). In vitro studies demonstrated that purified Cu(I)-yCCS protein is sufficient for direct copper activation of apo-ySOD1 but is necessary only when the concentration of free copper ions ([Cu] free ) is strictly limited. Moreover, the physiological requirement for yCCS in vivo was readily bypassed by elevated copper concentrations and abrogation of intracellular copper-scavenging systems such as the metallothioneins. This metallochaperone protein activates the target enzyme through direct insertion of the copper cofactor and apparently functions to protect the metal ion from binding to intracellular copper scavengers. These results indicate that intracellular [Cu] free is limited to less than one free copper ion per cell and suggest that a pool of free copper ions is not used in physiological activation of metalloenzymes.

Pigment epithelium-derived factor: a potent inhibitor of angiogenesis.

Abstract: In the absence of disease, the vasculature of the mammalian eye is quiescent, in part because of the action of angiogenic inhibitors that prevent vessels from invading the cornea and vitreous. Here, an inhibitor responsible for the avascularity of these ocular compartments is identified as pigment epithelium-derived factor (PEDF), a protein previously shown to have neurotrophic activity. The amount of inhibitory PEDF produced by retinal cells was positively correlated with oxygen concentrations, suggesting that its loss plays a permissive role in ischemia-driven retinal neovascularization. These results suggest that PEDF may be of therapeutic use, especially in retinopathies where pathological neovascularization compromises vision and leads to blindness.

Random laser action in semiconductor powder

Abstract: We report the first observation of random laser action with coherent feedback in semiconductor powder. Since the scattering mean free path is less than the emission wavelength, recurrent light scattering arises and provides coherent feedback for lasing. Discrete lasing modes have been observed above the threshold. The dependence of the lasing threshold intensity on the excitation volume agrees with the random laser theory. Laser emission from the powder could be observed in all directions. This observation also provides direct evidence for the existence of recurrent scattering of light.

Structure and phase transitions in Langmuir monolayers

Abstract: Lipid monolayers on the surface of water have been studied for over a hundred years, but in the last decade there has been a dramatic evolution in our understanding of the structures and phase transitions of these systems, driven by new experimental techniques and theoretical advances. In this review, dense monolayers of simple lipids are described in detail, including structures revealed by x-ray-diffraction experiments, computer simulations, molecular models, and a phenomenological theory of phase transitions. The effects of chirality and the structures of phospholipid monolayers are considered. Open questions and possible approaches to finding answers are discussed.

A direct-methane fuel cell with a ceria-based anode

Abstract: Fuel cells constitute an attractive power-generation technology that converts chemical energy directly and with high efficiency into electricity while causing little pollution. Most fuel cells require hydrogen as the fuel, but viable near-term applications will need to use the more readily available hydrocarbons, such as methane. Present-day demonstration power plants and planned fuel-cell electric vehicles therefore include a reformer that converts hydrocarbon fuel into hydrogen. Operating fuel cells directly on hydrocarbons would obviously eliminate the need for such a reformer and improve efficiency. In the case of polymer-electrolyte fuel cells, which have been studied for vehicle applications, the direct use of methanol fuel has been reported, but resulted in fuel permeating the electrolyte1,2. Solid oxide fuel cells — promising candidates for stationary power generation — can also use hydrocarbon fuel directly to generate energy, but this mode of operation resulted in either carbon deposition at high temperatures or poor power output at low operating temperatures3,4,5. Here we report the direct electrochemical oxidation of methane in solid oxide fuel cells that generate power densities upto 0.37 W cm−2 at 650 °C. This performance is comparable to that of fuel cells using hydrogen6,7 and is achieved by using ceria-containing anodes and low operating temperatures to avoid carbon deposition. We expect that the incorporation of more advanced cathodes would further improve the performance of our cells, making this solid oxide fuel cell a promising candidate for practical and efficient fuel-cell applications.

Addressing the Challenges of Inquiry-Based Learning Through Technology and Curriculum Design

Abstract: Inquiry experiences can provide valuable opportunities for students to improve their understanding of both science content and scientific practices. However, the implementation of inquiry learning in classrooms presents a number of significant challenges. We have been exploring these challenges through a program of research on the use of scientific visualization technologies to support inquiry-based learning in the geosciences. In this article, we describe 5 significant challenges to implementing inquiry-based learning and present strategies for addressing them through the design of technology and curriculum. We present a design history covering 4 generations of software and curriculum to show how these challenges arise in classrooms and how the design strategies respond to them.

Spatial attention and neglect: parietal, frontal and cingulate contributions to the mental representation and attentional targeting of salient extrapersonal events.

Abstract: The syndrome of contralesional neglect reflects a lateralized disruption of spatial attention. In the human, the left hemisphere shifts attention predominantly in the contralateral hemispace and in a contraversive direction whereas the right hemisphere distributes attention more evenly, in both hemispaces and both directions. As a consequence of this asymmetry, severe contralesional neglect occurs almost exclusively after right hemisphere lesions. Patients with left neglect experience a loss of salience in the mental representation and conscious perception of the left side and display a reluctance to direct orientating and exploratory behaviours to the left. Neglect is distributed according to egocentric, allocentric, world-centred, and object-centred frames of reference. Neglected events can continue to exert an implicit influence on behaviour, indicating that the attentional filtering occurs at the level of an internalized representation rather than at the level of peripheral sensory input. The unilateral neglect syndrome is caused by a dysfunction of a large-scale neurocognitive network, the cortical epicentres of which are located in posterior parietal cortex, the frontal eye fields, and the cingulate gyrus. This network coordinates all aspects of spatial attention, regardless of the modality of input or output. It helps to compile a mental representation of extrapersonal events in terms of their motivational salience, and to generate 'kinetic strategies' so that the attentional focus can shift from one target to another.

“I” Value Freedom, but “We” Value Relationships: Self-Construal Priming Mirrors Cultural Differences in Judgment

Abstract: The distinction between relatively independent versus interdependent self-construals has been strongly associated with several important cultural differences in social behavior. The current studies examined the causal role of self-construal by investigating whether priming independent or interdependent self-construals within a culture could result in differences in psychological worldview that mirror those traditionally found between cultures. In Experiment 1, European-American participants primed with interdependence displayed shifts toward more collectivist social values and judgments that were mediated by corresponding shifts in self-construal. In Experiment 2, this effect was extended by priming students from the United States and Hong Kong with primes that were consistent and inconsistent with their predominant cultural worldview. Students who received the inconsistent primes were more strongly affected than those who received the consistent primes, and thus shifted self-construal, and corresponding ...

Programmed Materials Synthesis with DNA.

Abstract: Learning how to control the formation and twoand three-dimensional assembly of molecular scale building blocks into well-defined mesoand macroscopic structures is the essence of nanotechnology and materials chemistry. DNA is arguably one of the most programmable “assemblers” available to the synthetic chemist and materials scientist, yet until recently, it has been an underutilized synthon in materials chemistry. The purpose of this review is to summarize advances made involving new strategies that rely on the use of both naturally occurring DNA and synthetic oligonucleotides to assemble nanoscale nonbiological building blocks into extended mesoand macroscopic structures. Although early in their development, some of these strategies already have been shown to be useful in generating novel nanostructured materials,1-4 arranging inorganic nanoparticles into “anatural” configurations,5,6 understanding interparticle electronic interactions,1 templating the growth of nanocircuitry,7 and developing a promising new detection technology for DNA.8,9 There are two basic types of building blocks that are applicable to a variety of assembly schemes: molecules with synthetically programmed recognition sites or bits of matter with nanoscale dimensions and well-defined surface chemistries. The latter type of building block is often referred to as a “nanoparticle” or “nanocrystal”. Assembly of such building blocks into extended, well-defined structures can provide a variety of functional materials with applications including ultrasmall electronic devices,10-13 spectroscopic enhancers,14,15 high-density information storage media,16,17 and highly sensitive and selective chemical detectors.8,9,18 The assembly of nanoparticle and molecular building blocks into functional structures has been accomplished through both physical and chemical methods.19 Physical methods include the use of scanning probe microscopy,20-22 electrophoretic strategies,23,24 LB films,25,26 or templatedriven sedimentation27 to position particles in a preconceived fashion within a matrix or on a substrate. Although effective for preparing certain types of nanoscale architectures, many of these physical methods are limited because they are often slow and do not lend themselves to preparing designed nanostructured architectures that canvas macroscopic dimensions. Chemical methods include ordering particles based upon interparticle electrostatic interactions,28-30 covalent assembly,31,32 template recognition,33,34 template recognition with subsequent covalent cross-linking reactions,35,36 crystallization based upon weak intermolecular interactions,37-41 or linking reactions involving designed organic or biological recognition sites.1,2,4,42 The advantages of chemical methods are that building block linking processes can occur in a massively parallel fashion and in some cases possess self-annealing or correcting properties. This makes them particularly attractive for constructing twoand three-dimensional structures on a faster time scale. The disadvantage is that at present chemical methods, when compared with some of the aforementioned physical deposition methods, are difficult to control. Recently, there has been substantial interest in utilizing biomolecules to direct the formation of extended mesoand macroscopic architectures.43,44 The advantage of using biomolecules is that molecular recognition is already built into the building block of interest (e.g., peptides, oligonucleotides, and proteins). In some cases, synthetic versions of the biomolecules are readily available and easily adaptable to both inorganic and organic building blocks and substrates.45 This review examines the use of one class of these biomolecules, DNA, to organize nanometer-sized structures into preconceived extended, functional structures and materials. It is divided into three categories; the use of (1) oligonucleotides (singlestranded DNA) to prepare mesoand macroscopic organic structures, (2) duplex DNA as a physical template for growing inorganic wires and organizing nonbiological building blocks into extended hybrid materials, and (3) oligonucleotide functionalized nanoparticles and sequence-specific hybridization reactions for organizing such particles into periodic, functional structures. 1849 Chem. Rev. 1999, 99, 1849−1862

Sexual transmission and propagation of SIV and HIV in resting and activated CD4+ T cells.

Abstract: In sexual transmission of simian immunodeficiency virus, and early and later stages of human immunodeficiency virus-type 1 (HIV-1) infection, both viruses were found to replicate predominantly in CD4(+) T cells at the portal of entry and in lymphoid tissues. Infection was propagated not only in activated and proliferating T cells but also, surprisingly, in resting T cells. The infected proliferating cells correspond to the short-lived population that produces the bulk of HIV-1. Most of the HIV-1-infected resting T cells persisted after antiretroviral therapy. Latently and chronically infected cells that may be derived from this population pose challenges to eradicating infection and developing an effective vaccine.

An evidence-based appraisal of reflux disease management — the Genval Workshop Report

Abstract: This report summarises conclusions from an evidence-based workshop which evaluated major clinical strategies for the management of the full spectrum of gastro-oesophageal reflux disease, with an emphasis on medical management. The disease was defined by the presence of oesophageal mucosal breaks or by the occurrence of reflux induced symptoms severe enough to impair quality of life. Endoscopy negative patients were recognised as the most common subgroup; most of these patients can be diagnosed by a well structured symptom analysis. There is a consistent hierarchy of effectiveness of available initial and long term therapies that applies for all patient subgroups. Lifestyle measures were judged to be of such low efficacy that they were rejected as a primary therapy for all patient subgroups. Proton pump inhibitor therapy was considered the initial medical treatment of choice because of its clearly superior efficacy which results in the most prompt achievement of desirable outcomes at the lowest overall medical cost. It was acknowledged that most of patients require long term management and that any maintenance therapy should be chosen by step down to the regimen that is still effective, but least costly. Endoscopic monitoring of routine long term therapy was considered inappropriate, on the basis that control of symptoms is an acceptably reliable indicator of healing in patients with oesophagitis. Laparoscopic antireflux surgery was recognised as a significant therapeutic advance, the results of which, however, depend substantially on the experience of the surgeon. There are currently no published direct comparisons of cost and efficacy outcomes of optimal medical and surgical therapies for reflux disease. To a significant degree, the choice between medical and surgical therapy should depend on informed patient preference. Substantial advances have occurred recently in the understanding and treatment of reflux disease. By contrast, there has been relatively little research into the best …

Treatment of Patients With Low-Grade B-Cell Lymphoma With the Combination of Chimeric Anti-CD20 Monoclonal Antibody and CHOP Chemotherapy

Abstract: PURPOSE: To determine the safety and efficacy of the combination of the chimeric anti-CD20 antibody, Rituxan (Rituximab, IDEC-C2B8; IDEC Pharmaceuticals Corporation, San Diego, CA), and cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) chemotherapy. PATIENTS AND METHODS: Forty patients with low-grade or follicular B-cell non–Hodgkin's lymphoma received six infusions of Rituxan (375 mg/m2 per dose) in combination with six doses of CHOP chemotherapy. RESULTS: The overall response rate was 95% (38 of 40 patients). Twenty-two patients experienced a complete response (55%), 16 patients had a partial response (40%), and two patients, who received no treatment, were classified as nonresponders. Medians for duration of response and time to progression had not been reached after a median observation time of 29 + months. Twenty-eight of 38 assessable patients (74%) continued in remission during this median follow-up period. The most frequent adverse events attributable to CHOP were alopecia (38 pati...

A case for including spirituality in quality of life measurement in oncology

Abstract: Most of the commonly used quality of life (QOL) instruments in oncology do not include spirituality as a core domain. However, previous research suggests that spirituality might be an important aspect of QOL for cancer patients and that it may, in fact, be especially salient in the context of life-threatening illness. This study used a large (n=1610) and ethnically diverse sample to address three questions relevant to including spirituality in QOL measurement: (1) Does spirituality demonstrate a positive association with QOL?; (2) Is this association unique?; and (3) Is there clinical utility in including spirituality in QOL measurement? Spirituality, as measured by the Functional Assessment of Chronic Illness Therapy-Spiritual Well-Being (FACIT-Sp), was found to be associated with QOL to the same degree as physical well-being, a domain unquestioned in its importance to QOL. The significant association between spirituality and QOL was unique, remaining after controlling for core QOL domains as well as other possible confounding variables. Furthermore, spiritual well-being was found to be related to the ability to enjoy life even in the midst of symptoms, making this domain a potentially important clinical target. It is concluded that these results support the move to the biopsychosocialspiritual model for QOL measurement in oncology.

Maternal levels of plasma human immunodeficiency virus type 1 RNA and the risk of perinatal transmission

Abstract: Background The importance of plasma levels of human immunodeficiency virus type 1 (HIV-1) RNA in pregnant women in relation to the other factors known to influence the risk of transmission of infection to their infants is incompletely defined. We studied the relation of maternal plasma HIV-1 RNA levels to the risk of perinatal transmission and the timing of transmission. Methods We measured plasma HIV-1 RNA serially in 552 women with HIV-1 infection who had singleton pregnancies. The status of infection in their infants was assessed by culture of blood and further classified as early (if a culture of blood obtained within the first two days of life was positive) or late (if a culture of blood obtained in the first seven days of life was negative but subsequent cultures were positive). The rates of transmission at various levels of maternal plasma HIV-1 RNA were analyzed by tests for trend, with adjustment for covariates by stratification and logistic regression. Results Increasing geometric mean levels of...

Gender-Stereotypic Images of Occupations Correspond to the Sex Segregation of Employment

Abstract: This study examines the role of gender stereotypes in justifying the social system by maintaining the division of labor between the sexes. The distribution of the sexes in 80 occupations was predicted from participants’ beliefs that six dimensions of gender-stereotypic attributes contribute to occupational success: masculine physical, feminine physical, masculine personality, feminine personality, masculine cognitive, and feminine cognitive. Findings showed that, to the extent that occupations were female dominated, feminine personality or physical attributes were thought more essential for success; to the extent that occupations were male dominated, masculine personality or physical attributes were thought more essential. Demonstrating the role of gender stereotypes in justifying gender hierarchy, occupations had higher prestige in that participants believed that they required masculine personality or cognitive attributes for success, and they had higher earnings to the extent that they were thought to r...

Low risk-factor profile and long-term cardiovascular and noncardiovascular mortality and life expectancy: findings for 5 large cohorts of young adult and middle-aged men and women.

Abstract: ContextThree major coronary risk factors—serum cholesterol level, blood pressure, and smoking—increase incidence of coronary heart disease (CHD) and related end points. In previous investigations, risks for low-risk reference groups were estimated statistically because samples contained too few such people to measure risk.ObjectiveTo measure long-term mortality rates for individuals with favorable levels for all 3 major risk factors, compared with others.DesignTwo prospective studies, involving 5 cohorts based on age and sex, that enrolled persons with a range of risk factors. Low risk was defined as serum cholesterol level less than 5.17 mmol/L (<200 mg/dL), blood pressure less than or equal to120/80 mm Hg, and no current cigarette smoking. All persons with a history of diabetes, myocardial infarction (MI), or, in 3 of 5 cohorts, electrocardiogram (ECG) abnormalities, were excluded.Setting and ParticipantsIn 18 US cities, a total of 72,144 men aged 35 through 39 years and 270,671 men aged 40 through 57 years screened (1973-1975) for the Multiple Risk Factor Intervention Trial (MRFIT); in Chicago, a total of 10,025 men aged 18 through 39 years, 7490 men aged 40 through 59 years, and 6229 women aged 40 through 59 years screened (1967-1973) for the Chicago Heart Association Detection Project in Industry (CHA) (N = 366,559).Main Outcome MeasuresCause-specific mortality during 16 (MRFIT) and 22 (CHA) years, relative risks (RRs) of death, and estimated greater life expectancy, comparing low-risk subcohorts vs others by age strata.ResultsLow-risk persons comprised only 4.8% to 9.9% of the cohorts. All 5 low-risk groups experienced significantly and markedly lower CHD and cardiovascular disease death rates than those who had elevated cholesterol level, or blood pressure, or smoked. For example, age-adjusted RRs of CHD mortality ranged from 0.08 for CHA men aged 18 to 39 years to 0.23 for CHA men aged 40 through 59 years. The age-adjusted relative risks (RRs) for all cardiovascular disease mortality ranged from 0.15 for MRFIT men aged 35 through 39 years to 0.28 for CHA men aged 40 through 59 years. The age-adjusted RR for all-cause mortality rate ranged from 0.42 for CHA men aged 40 through 59 years to 0.60 for CHA women aged 40 through 59 years. Estimated greater life expectancy for low-risk groups ranged from 5.8 years for CHA women aged 40 through 59 years to 9.5 years for CHA men aged 18 through 39 years.ConclusionsBased on these very large cohort studies, for individuals with favorable levels of cholesterol and blood pressure who do not smoke and do not have diabetes, MI, or ECG abnormalities, long-term mortality is much lower and longevity is much greater. A substantial increase in the proportion of the population at lifetime low risk could contribute decisively to ending the CHD epidemic.

Nanosphere Lithography: Size-Tunable Silver Nanoparticle and Surface Cluster Arrays

Abstract: Nanosphere lithography (NSL) is an inexpensive, inherently parallel, high-throughput, and materials-general nanofabrication technique capable of producing well-ordered 2D periodic particle arrays of nanoparticles. This paper focuses on the synthesis of size-tunable silver nanoparticle arrays by nanosphere lithography and their structural characterization by atomic force microscopy (AFM). The in-plane diameter, a, of Ag nanoparticles was tuned from 21 to 126 nm by systematic variation of the nanosphere diameter, D. Similarly, the out-of-plane height, b, was tuned from 4 to 47 nm by varying the mass thickness, dm, of the Ag overlayer. Experimental measurements of a, b, and interparticle spacing dip of many individual nanoparticles as a function of D and dm were carried out using AFM. These studies show (i) b = dm, (ii) dip accurately corresponds to predictions based on the nanosphere mask geometry, (iii) a, after correction for AFM tip convolution, is governed only by the mask geometry and the standard devi...

Dietary Fiber, Weight Gain, and Cardiovascular Disease Risk Factors in Young Adults

Abstract: ContextDietary composition may affect insulin secretion, and high insulin levels, in turn, may increase the risk for cardiovascular disease (CVD).ObjectiveTo examine the role of fiber consumption and its association with insulin levels, weight gain, and other CVD risk factors compared with other major dietary components.Design and SettingThe Coronary Artery Risk Development in Young Adults (CARDIA) Study, a multicenter population-based cohort study of the change in CVD risk factors over 10 years (1985-1986 to 1995-1996) in Birmingham, Ala; Chicago, Ill; Minneapolis, Minn; and Oakland, Calif.ParticipantsA total of 2909 healthy black and white adults, 18 to 30 years of age at enrollment.Main Outcome MeasuresBody weight, insulin levels, and other CVD risk factors at year 10, adjusted for baseline values.ResultsAfter adjustment for potential confounding factors, dietary fiber showed linear associations from lowest to highest quintiles of intake with the following: body weight (whites: 174.8-166.7 lb [78.3-75.0 kg], P<.001; blacks: 185.6-177.6 lb [83.5-79.9 kg], P = .001), waist-to-hip ratio (whites: 0.813-0.801, P = .004; blacks: 0.809-0.799, P = .05), fasting insulin adjusted for body mass index (whites: 77.8-72.2 pmol/L [11.2-10.4 µU/mL], P = .007;blacks: 92.4-82.6 pmol/L [13.3-11.9 µU/mL], P = .01) and 2-hour postglucose insulin adjusted for body mass index (whites: 261.1-234.7 pmol/L [37.6-33.8 µU/mL], P = .03; blacks: 370.2-259.7 pmol/L [53.3-37.4 µU/mL], P<.001). Fiber was also associated with blood pressure and levels of triglyceride, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, and fibrinogen; these associations were substantially attenuated by adjustment for fasting insulin level. In comparison with fiber, intake of fat, carbohydrate, and protein had inconsistent or weak associations with all CVD risk factors.ConclusionsFiber consumption predicted insulin levels, weight gain, and other CVD risk factors more strongly than did total or saturated fat consumption. High-fiber diets may protect against obesity and CVD by lowering insulin levels.