Showing papers by "Northwestern University published in 2009"
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27 Apr 200910,518 citations
TL;DR: In this article, the authors examine the different methods used in the literature and explain when the different approaches yield the same (and correct) standard errors and when they diverge, and give researchers guidance for their use.
Abstract: In both corporate finance and asset pricing empirical work, researchers are often confronted with panel data. In these data sets, the residuals may be correlated across firms and across time, and OLS standard errors can be biased. Historically, the two literatures have used different solutions to this problem. Corporate finance has relied on clustered standard errors, while asset pricing has used the Fama-MacBeth procedure to estimate standard errors. This paper examines the different methods used in the literature and explains when the different methods yield the same (and correct) standard errors and when they diverge. The intent is to provide intuition as to why the different approaches sometimes give different answers and give researchers guidance for their use.
7,647 citations
TL;DR: A critical review of the emerging field of MOF-based catalysis is presented and examples of catalysis by homogeneous catalysts incorporated as framework struts or cavity modifiers are presented.
Abstract: A critical review of the emerging field of MOF-based catalysis is presented. Discussed are examples of: (a) opportunistic catalysis with metal nodes, (b) designed catalysis with framework nodes, (c) catalysis by homogeneous catalysts incorporated as framework struts, (d) catalysis by MOF-encapsulated molecular species, (e) catalysis by metal-free organic struts or cavity modifiers, and (f) catalysis by MOF-encapsulated clusters (66 references).
7,010 citations
TL;DR: This work has revealed unexpected diversity in their biogenesis pathways and the regulatory mechanisms that they access, which has direct implications for fundamental biology as well as disease etiology and treatment.
4,490 citations
TL;DR: Rehospitalizations among Medicare beneficiaries are prevalent and costly and about 10% of rehospitalizations were likely to have been planned.
Abstract: Background Reducing rates of rehospitalization has attracted attention from policymakers as a way to improve quality of care and reduce costs. However, we have limited information on the frequency and patterns of rehospitalization in the United States to aid in planning the necessary changes. Methods We analyzed Medicare claims data from 2003–2004 to describe the patterns of rehospitalization and the relation of rehospitalization to demographic characteristics of the patients and to characteristics of the hospitals. Results Almost one fifth (19.6%) of the 11,855,702 Medicare beneficiaries who had been discharged from a hospital were rehospitalized within 30 days, and 34.0% were rehospitalized within 90 days; 67.1% of patients who had been discharged with medical conditions and 51.5% of those who had been discharged after surgical procedures were rehospitalized or died within the first year after discharge. In the case of 50.2% of the patients who were rehospitalized within 30 days after a medical discharg...
4,438 citations
TL;DR: In this paper, several nanometer-thick graphene oxide films were exposed to nine different heat treatments (three in Argon, three in Argon and Hydrogen, and three in ultra-high vacuum), and also a film was held at 70°C while being exposed to a vapor from hydrazine monohydrate.
2,990 citations
TL;DR: A review of 122 research reports (184 independent samples, 14,900 subjects) found average r =.274 for prediction of behavioral, judgment, and physiological measures by Implicit Association Test (IAT) measures as mentioned in this paper.
Abstract: This review of 122 research reports (184 independent samples, 14,900 subjects) found average r = .274 for prediction of behavioral, judgment, and physiological measures by Implicit Association Test (IAT) measures. Parallel explicit (i.e., self-report) measures, available in 156 of these samples (13,068 subjects), also predicted effectively (average r = .361), but with much greater variability of effect size. Predictive validity of self-report was impaired for socially sensitive topics, for which impression management may distort self-report responses. For 32 samples with criterion measures involving Black-White interracial behavior, predictive validity of IAT measures significantly exceeded that of self-report measures. Both IAT and self-report measures displayed incremental validity, with each measure predicting criterion variance beyond that predicted by the other. The more highly IAT and self-report measures were intercorrelated, the greater was the predictive validity of each.
2,690 citations
TL;DR: In this article, a field is emerging that leverages the capacity to collect and analyze data at a scale that may reveal patterns of individual and group behaviors at a large scale, such as behavior patterns.
Abstract: A field is emerging that leverages the capacity to collect and analyze data at a scale that may reveal patterns of individual and group behaviors.
2,619 citations
TL;DR: In this article, a systematic literature search was conducted for observational cohort studies using MEDLINE (1966 to December 31, 2008) and EMBASE (1980 to December 30, 2008), which reported associations of baseline cardiorespiratory fitness with CHD events, CVD events, or all-cause mortality in healthy participants.
Abstract: Context Epidemiological studies have indicated an inverse association between cardiorespiratory fitness (CRF) and coronary heart disease (CHD) or all-cause mortality in healthy participants. Objective To define quantitative relationships between CRF and CHD events, cardiovascular disease (CVD) events, or all-cause mortality in healthy men and women. Data Sources and Study Selection A systematic literature search was conducted for observational cohort studies using MEDLINE (1966 to December 31, 2008) and EMBASE (1980 to December 31, 2008). The Medical Subject Headings search terms used included exercise tolerance, exercise test, exercise/physiology, physical fitness, oxygen consumption, cardiovascular diseases, myocardial ischemia, mortality, mortalities, death, fatality, fatal, incidence, or morbidity. Studies reporting associations of baseline CRF with CHD events, CVD events, or all-cause mortality in healthy participants were included. Data Extraction Two authors independently extracted relevant data. CRF was estimated as maximal aerobic capacity (MAC) expressed in metabolic equivalent (MET) units. Participants were categorized as low CRF ( Data Synthesis Data were obtained from 33 eligible studies (all-cause mortality, 102 980 participants and 6910 cases; CHD/CVD, 84 323 participants and 4485 cases). Pooled RRs of all-cause mortality and CHD/CVD events per 1-MET higher level of MAC (corresponding to 1-km/h higher running/jogging speed) were 0.87 (95% confidence interval [CI], 0.84-0.90) and 0.85 (95% CI, 0.82-0.88), respectively. Compared with participants with high CRF, those with low CRF had an RR for all-cause mortality of 1.70 (95% CI, 1.51-1.92; P Conclusions Better CRF was associated with lower risk of all-cause mortality and CHD/CVD. Participants with a MAC of 7.9 METs or more had substantially lower rates of all-cause mortality and CHD/CVD events compared with those with a MAC of less 7.9 METs.
2,464 citations
Harvard University1, University of Massachusetts Medical School2, Massachusetts Institute of Technology3, Rhode Island Hospital4, University of Kentucky5, Tufts University6, Université de Montréal7, University of Bologna8, Children's Hospital Oakland Research Institute9, Vanderbilt University10, Northwestern University11, University of Milan12
TL;DR: Neuronal cytoplasmic protein aggregation and defective RNA metabolism thus appear to be common pathogenic mechanisms involved in ALS and possibly in other neurodegenerative disorders.
Abstract: Amyotrophic lateral sclerosis (ALS) is a fatal degenerative motor neuron disorder Ten percent of cases are inherited; most involve unidentified genes We report here 13 mutations in the fused in sarcoma/translated in liposarcoma (FUS/TLS) gene on chromosome 16 that were specific for familial ALS The FUS/TLS protein binds to RNA, functions in diverse processes, and is normally located predominantly in the nucleus In contrast, the mutant forms of FUS/TLS accumulated in the cytoplasm of neurons, a pathology that is similar to that of the gene TAR DNA-binding protein 43 (TDP43), whose mutations also cause ALS Neuronal cytoplasmic protein aggregation and defective RNA metabolism thus appear to be common pathogenic mechanisms involved in ALS and possibly in other neurodegenerative disorders
2,387 citations
Boston University1, Saint Louis University2, Northwestern University3, University of Texas MD Anderson Cancer Center4, University of North Carolina at Chapel Hill5, Mashantucket Pequot Tribal Nation6, Columbia University7, University of California, San Francisco8, National Institutes of Health9, Yale Cancer Center10, University of Texas Health Science Center at Houston11
TL;DR: The diverse types of feasibility studies conducted in the field of cancer prevention, using a group of recently funded grants from the National Cancer Institute are described.
TL;DR: The most promising bulk materials with emphasis on results from the last decade are described and the new opportunities for enhanced performance bulk nanostructured composite materials are examined and a look into the not so distant future is attempted.
Abstract: Herein we cover the key concepts in the field of thermoelectric materials research, present the current understanding, and show the latest developments. Current research is aimed at increasing the thermoelectric figure of merit (ZT) by maximizing the power factor and/or minimizing the thermal conductivity. Attempts at maximizing the power factor include the development of new materials, optimization of existing materials by doping, and the exploration of nanoscale materials. The minimization of the thermal conductivity can come through solid-solution alloying, use of materials with intrinsically low thermal conductivity, and nanostructuring. Herein we describe the most promising bulk materials with emphasis on results from the last decade. Single-phase bulk materials are discussed in terms of chemistry, crystal structure, physical properties, and optimization of thermoelectric performance. The new opportunities for enhanced performance bulk nanostructured composite materials are examined and a look into the not so distant future is attempted.
Harvard University1, Hospital de Base2, The Heart Research Institute3, University of Groningen4, University of Erlangen-Nuremberg5, University of Wisconsin-Madison6, Northwestern University7, Tufts University8, Washington University in St. Louis9, St. John's University10, Aarhus University11, University of Copenhagen12, University of Texas Southwestern Medical Center13
TL;DR: The use of darbepoetin alfa in patients with diabetes, chronic kidney disease, and moderate anemia who were not undergoing dialysis did not reduce the risk of either of the two primary composite outcomes (either death or a cardiovascular event ordeath or a renal event) and was associated with an increased risk of stroke.
Abstract: Background Anemia is associated with an increased risk of cardiovascular and renal events among patients with type 2 diabetes and chronic kidney disease. Although darbepoetin alfa can effectively increase hemoglobin levels, its effect on clinical outcomes in these patients has not been adequately tested. Methods In this study involving 4038 patients with diabetes, chronic kidney disease, and anemia, we randomly assigned 2012 patients to darbepoetin alfa to achieve a hemoglobin level of approximately 13 g per deciliter and 2026 patients to placebo, with rescue darbepoetin alfa when the hemoglobin level was less than 9.0 g per deciliter. The primary end points were the composite outcomes of death or a cardiovascular event (nonfatal myocardial infarction, congestive heart failure, stroke, or hospitalization for myocardial ischemia) and of death or end-stage renal disease. Results Death or a cardiovascular event occurred in 632 patients assigned to darbepoetin alfa and 602 patients assigned to placebo (hazard...
TL;DR: Single-layer graphite oxide can be viewed as an unconventional type of soft material and has recently been recognized as a promising material for composite and electronics applications and it is of both scientific curiosity and technical importance to know how these atomically thin sheets assemble.
Abstract: Single-layer graphite oxide can be viewed as an unconventional type of soft material and has recently been recognized as a promising material for composite and electronics applications. It is of both scientific curiosity and technical importance to know how these atomically thin sheets assemble. There are two fundamental geometries of interacting single layers: edge-to-edge and face-to-face. Such interactions were studied at the air−water interface by Langmuir−Blodgett assembly. Stable monolayers of graphite oxide single layers were obtained without the need for any surfactant or stabilizing agent, due to the strong electrostatic repulsion between the 2D confined layers. Such repulsion also prevented the single layers from overlapping during compression, leading to excellent reversibility of the monolayers. In contrast to molecular and hard colloidal particle monolayers, the single layers tend to fold and wrinkle at edges to resist collapsing into multilayers. The monolayers can be transferred to a substr...
Ohio State University1, National Institutes of Health2, George Washington University3, Brown University4, University of Texas Health Science Center at Houston5, University of Texas Southwestern Medical Center6, Columbia University7, University of Utah8, University of Alabama at Birmingham9, University of North Carolina at Chapel Hill10, Drexel University11, Case Western Reserve University12, Wake Forest University13, University of Texas Medical Branch14, University of Pittsburgh15, Wayne State University16, Northwestern University17, Oregon Health & Science University18
TL;DR: Treatment of mild gestational diabetes mellitus did not significantly reduce the frequency of a composite outcome that included stillbirth or perinatal death and several neonatal complications, but it did reduce the risks of fetal overgrowth, shoulder dystocia, cesarean delivery, and hypertensive disorders.
Abstract: Background It is uncertain whether treatment of mild gestational diabetes mellitus improves pregnancy outcomes. Methods Women who were in the 24th to 31st week of gestation and who met the criteria for mild gestational diabetes mellitus (i.e., an abnormal result on an oral glucose-tolerance test but a fasting glucose level below 95 mg per deciliter [5.3 mmol per liter]) were randomly assigned to usual prenatal care (control group) or dietary intervention, self-monitoring of blood glucose, and insulin therapy, if necessary (treatment group). The primary outcome was a composite of stillbirth or perinatal death and neonatal complications, including hyperbilirubinemia, hypoglycemia, hyperinsulinemia, and birth trauma. Results A total of 958 women were randomly assigned to a study group — 485 to the treatment group and 473 to the control group. We observed no significant difference between groups in the frequency of the composite outcome (32.4% and 37.0% in the treatment and control groups, respectively; P=0.1...
University of Louisville1, University of Pittsburgh2, Royal Brisbane and Women's Hospital3, Carolinas Medical Center4, Beaumont Hospital5, University of Cincinnati6, Seoul National University7, Iwate Medical University8, Toho University9, Kaohsiung Medical University10, University of Paris11, University of Texas MD Anderson Cancer Center12, McGill University13, University of California, Los Angeles14, Memorial Sloan Kettering Cancer Center15, Mayo Clinic16, University of Chicago17, Icahn School of Medicine at Mount Sinai18, University of Hong Kong19, Duke University20, Vanderbilt University21, Roger Williams Medical Center22, Northwestern University23, University of Duisburg-Essen24, Washington University in St. Louis25
TL;DR: Laparoscopic liver surgery is a safe and effective approach to the management of surgical liver disease in the hands of trained surgeons with experience in hepatobiliary and laparoscopic surgery, and national and international societies should become involved in the goal of establishing training standards and credentialing.
Abstract: Objective:To summarize the current world position on laparoscopic liver surgery.Summary Background Data:Multiple series have reported on the safety and efficacy of laparoscopic liver surgery. Small and medium sized procedures have become commonplace in many centers, while major laparoscopic liver re
TL;DR: This Review provides a critical examination of the various interparticle forces (van der Waals, electrostatic, magnetic, molecular, and entropic) that can be used in nanoscale self-assembly.
Abstract: The ability to assemble nanoscopic components into larger structures and materials depends crucially on the ability to understand in quantitative detail and subsequently "engineer" the interparticle interactions. This Review provides a critical examination of the various interparticle forces (van der Waals, electrostatic, magnetic, molecular, and entropic) that can be used in nanoscale self-assembly. For each type of interaction, the magnitude and the length scale are discussed, as well as the scaling with particle size and interparticle distance. In all cases, the discussion emphasizes characteristics unique to the nanoscale. These theoretical considerations are accompanied by examples of recent experimental systems, in which specific interaction types were used to drive nanoscopic self-assembly. Overall, this Review aims to provide a comprehensive yet easily accessible resource of nanoscale-specific interparticle forces that can be implemented in models or simulations of self-assembly processes at this scale.
TL;DR: A facile two-step aqueous approach to immobilization of biomolecules onto surfaces is reported, which exploits the latent reactivity of the biomimetic polymer thin film towards nucleophiles, is unaffected by water, and allows for discrimination betweenucleophiles on the basis of pKa.
Abstract: Immobilization of biomolecules onto surfaces is important in many of the biological and physical sciences, including cell and molecular biology, analytical chemistry, and in applied and interdisciplinary fields such as medical diagnostics, tissue engineering, and bioprocess engineering.[1-4] Strategies for biomolecule immobilization onto surfaces generally exploit either noncovalent or covalent reactions. Noncovalent methods allow reversible immobilization of biomolecules under specific conditions, and include physical adsorption and affinity immobilization. Some widely adapted examples are (strep)avidin-biotin, nitriloacetic acid (NTA)-histidine, and DNA-DNA interactions.[5-8] In contrast, covalent immobilization of molecules onto surfaces typically relies on conjugation reactions between ‘active’ functional groups, such as N-hydroxysuccinimide (NHS)[9] or maleimide,[10] and companion target moieties, such as amines and sulfhydryls. For reactions involving biomolecules performed in aqueous solvents, susceptibility of NHS, maleimide, and other activating groups to hydrolysis during storage and reaction can lead to low efficiency of surface bioconjugation.[11,12] In this study, we report a facile two-step aqueous approach to immobilization of biomolecules onto surfaces. The approach involves simple dip-coating of a biomimetic polymer thin film onto a substrate, followed by conjugation of biomolecules to the biomimetic polymer film. The method exploits the latent reactivity of the biomimetic polymer thin film towards nucleophiles, is unaffected by water, and allows for discrimination between nucleophiles on the basis of pKa.
TL;DR: This paper used data on bilateral trust between European countries and found that lower bilateral trust leads to less trade between two countries, less portfolio investment, and less direct investment, even after controlling for the characteristics of the two countries.
Abstract: How much do cultural biases affect economic exchange? We answer this question by using data on bilateral trust between European countries. We document that this trust is affected not only by the characteristics of the country being trusted, but also by cultural aspects of the match between trusting country and trusted country, such as their history of conflicts and their religious, genetic, and somatic similarities. We then find that lower bilateral trust leads to less trade between two countries, less portfolio investment, and less direct investment, even after controlling for the characteristics of the two countries. This effect is stronger for goods that are more trust intensive. Our results suggest that perceptions rooted in culture are important (and generally omitted) determinants of economic exchange.
University of California, Davis1, Columbia University2, Spectrum Health3, George Washington University4, University of Utah5, University of Pennsylvania6, Johns Hopkins University7, University of Michigan8, University of Rochester9, Washington University in St. Louis10, Wayne State University11, University of Maryland, Baltimore12, University at Buffalo13, New York University14, Holy Cross Hospital15, State University of New York Upstate Medical University16, Medical College of Wisconsin17, University of Cincinnati18, Harvard University19, Saint Barnabas Medical Center20, Northwestern University21, Memorial Hospital of South Bend22, Calvert Memorial Hospital23
TL;DR: These validated prediction rules identified children at very low risk of clinically-important traumatic brain injuries (ciTBI) for whom CT might be unnecessary and missed neurosurgery in validation populations.
Veterans Health Administration1, Northwestern University2, University of Nebraska Omaha3, University of Pennsylvania4, University of California, San Francisco5, University of Michigan6, National Institutes of Health7, University of Kansas8, Oregon Health & Science University9, Portland VA Medical Center10, United States Department of Veterans Affairs11, Baylor College of Medicine12, Virginia Commonwealth University13, University of Iowa14
TL;DR: Deep brain stimulation was more effective than best medical therapy in improving on time without troubling dyskinesias, motor function, and quality of life at 6 months, but was associated with an increased risk of serious adverse events.
Abstract: Context Deep brain stimulation is an accepted treatment for advanced Parkinson disease (PD), although there are few randomized trials comparing treatments, and most studies exclude older patients. Objective To compare 6-month outcomes for patients with PD who received deep brain stimulation or best medical therapy. Design, Setting, and Patients Randomized controlled trial of patients who received either deep brain stimulation or best medical therapy, stratified by study site and patient age ( Intervention Bilateral deep brain stimulation of the subthalamic nucleus (n = 60) or globus pallidus (n = 61). Patients receiving best medical therapy (n = 134) were actively managed by movement disorder neurologists. Main Outcome Measures The primary outcome was time spent in the “on” state (good motor control with unimpeded motor function) without troubling dyskinesia, using motor diaries. Other outcomes included motor function, quality of life, neurocognitive function, and adverse events. Results Patients who received deep brain stimulation gained a mean of 4.6 h/d of on time without troubling dyskinesia compared with 0 h/d for patients who received best medical therapy (between group mean difference, 4.5 h/d [95% CI, 3.7-5.4 h/d]; P Conclusion In this randomized controlled trial of patients with advanced PD, deep brain stimulation was more effective than best medical therapy in improving on time without troubling dyskinesias, motor function, and quality of life at 6 months, but was associated with an increased risk of serious adverse events. Trial Registration clinicaltrials.gov Identifier: NCT00056563
TL;DR: The results indicate that the intrinsic DNA sequence preferences of nucleosomes have a central role in determining the organization ofucleosomes in vivo.
Abstract: The nucleosomes are the basic repeating units of eukaryotic chromatin, and nucleosome organization is critically important for gene regulation. Kaplan et al. tested the importance of the intrinsic DNA sequence preferences of nucleosomes by measuring the genome-wide occupancy of nucleosomes assembled on purified yeast genomic DNA. The resulting map is remarkably similar to in vivo nucleosome maps, indicating that the organization of nucleosomes in vivo is largely governed by the underlying genomic DNA sequence. This study tests the importance of the intrinsic DNA sequence preferences of nucleosomes by measuring the genome-wide occupancy of nucleosomes assembled on purified yeast genomic DNA. The resulting map is similar to in vivo nucleosome maps, indicating that the organization of nucleosomes in vivo is largely governed by the underlying genomic DNA sequence. Nucleosome organization is critical for gene regulation1. In living cells this organization is determined by multiple factors, including the action of chromatin remodellers2, competition with site-specific DNA-binding proteins3, and the DNA sequence preferences of the nucleosomes themselves4,5,6,7,8. However, it has been difficult to estimate the relative importance of each of these mechanisms in vivo7,9,10,11, because in vivo nucleosome maps reflect the combined action of all influencing factors. Here we determine the importance of nucleosome DNA sequence preferences experimentally by measuring the genome-wide occupancy of nucleosomes assembled on purified yeast genomic DNA. The resulting map, in which nucleosome occupancy is governed only by the intrinsic sequence preferences of nucleosomes, is similar to in vivo nucleosome maps generated in three different growth conditions. In vitro, nucleosome depletion is evident at many transcription factor binding sites and around gene start and end sites, indicating that nucleosome depletion at these sites in vivo is partly encoded in the genome. We confirm these results with a micrococcal nuclease-independent experiment that measures the relative affinity of nucleosomes for ∼40,000 double-stranded 150-base-pair oligonucleotides. Using our in vitro data, we devise a computational model of nucleosome sequence preferences that is significantly correlated with in vivo nucleosome occupancy in Caenorhabditis elegans. Our results indicate that the intrinsic DNA sequence preferences of nucleosomes have a central role in determining the organization of nucleosomes in vivo.
TL;DR: In this article, it was shown that α is not appropriate when considering how well a test measures one concept, but recommend ωt rather than the glb, and the end user needs procedures that are readily available in open source software.
Abstract: There are three fundamental problems in Sijtsma (Psychometrika, 2008): (1) contrary to the name, the glb is not the greatest lower bound of reliability but rather is systematically less than ωt (McDonald, Test theory: A unified treatment, Erlbaum, Hillsdale, 1999), (2) we agree with Sijtsma that when considering how well a test measures one concept, α is not appropriate, but recommend ωt rather than the glb, and (3) the end user needs procedures that are readily available in open source software.
TL;DR: Two dimensions representing physical and mental health underlie the global health items in PROMIS and these global health scales can be used to efficiently summarize physical andmental health in patient-reported outcome studies.
Abstract: Background
The use of global health items permits an efficient way of gathering general perceptions of health. These items provide useful summary information about health and are predictive of health care utilization and subsequent mortality.
TL;DR: Results from randomized controlled trials have demonstrated conclusively that the risk of microvascular complications can be reduced by intensive glycemic control in patients with type 1 and type 2 diabetes, leading the American Diabetes Association to recommend an A1C goal of <7% for most adults with diabetes.
Abstract: Diabetes is defined by its association with hyperglycemia-specific microvascular complications; however, it also imparts a two- to fourfold risk of cardiovascular disease (CVD). Although microvascular complications can lead to significant morbidity and premature mortality, by far the greatest cause of death in people with diabetes is CVD.
Results from randomized controlled trials have demonstrated conclusively that the risk of microvascular complications can be reduced by intensive glycemic control in patients with type 1 (1,2) and type 2 diabetes (3–5). In the Diabetes Control and Complications Trial (DCCT), there was an ∼60% reduction in development or progression of diabetic retinopathy, nephropathy, and neuropathy between the intensively treated group (goal A1C <6.05%, mean achieved A1C ∼7%) and the standard group (A1C ∼9%) over an average of 6.5 years. The relationship between glucose control (as reflected by the mean on-study A1C value) and risk of complications was log-linear and extended down to the normal A1C range (<6%) with no threshold noted.
In the UK Prospective Diabetes Study (UKPDS), participants newly diagnosed with type 2 diabetes were followed for 10 years, and intensive control (median A1C 7.0%) was found to reduce the overall microvascular complication rate by 25% compared with conventional treatment (median A1C 7.9%). Here, too, secondary analyses showed a continuous relationship between the risk of microvascular complications and glycemia extending into the normal range of A1C, with no glycemic threshold.
On the basis of these two large controlled trials, along with smaller studies and numerous epidemiologic reports, the consistent findings related to microvascular risk reduction with intensive glycemic control have led the American Diabetes Association (ADA) to recommend an A1C goal of <7% for most adults with diabetes (6), recognizing that more or less stringent goals may be appropriate for certain patients. Whereas many epidemiologic studies and meta-analyses …
TL;DR: Shapiro, Skowronek, and Galvin editaron un libro that puso al dia el estudio de las instituciones al presentar un conjunto de traba-jos representativos de las principales tradiciones in el eststudio del tema as mentioned in this paper.
Abstract: En el ano 2006 Shapiro, Skowronek y Galvin editaron un libro que puso al dia el estudio de las instituciones al presentar un conjunto de traba- jos representativos de las principales tradiciones en el estudio del tema. Los editores no pidieron a los autores que abandonaran su enfoque para mimetizarse -o dialogar- con los demas; en vez de eso, les pidieron que asumieran con claridad su postura, pero presentandola de forma atractiva para aquellos colegas que pertenecian a otras dis- ciplinas o corrientes. El libro reunio importantes aportaciones de John Elster, Clauss Offe, John Ferejohn, Rogers Smith, entre otros. En aquella obra Kathleen Thelen aporto una critica a la teoria del equilibrio interrumpido, que es la forma mas comun de ver el cambio segun dos de los institucionalismos mas prominentes: el his- torico y el de la eleccion racional. Oponiendose a la idea de que las instituciones unicamente cambian en momentos breves de intensa transformacion -casi siempre producto de algun shock exogeno, para luego entrar en largos periodos de reproduc- cion e inercia-, la autora propuso que el cambio institucional muchas veces es un proceso gradual y continuo. Mediante el ana- lisis de las instituciones dedicadas al entrenamiento
TL;DR: This Account explores how self-assembly strategies involving pi-stacking can be used to integrate light harvesting with charge separation and transport, and takes advantage of the shapes, sizes, and intermolecular interactions of these molecules to direct the formation of supramolecular structures having enhanced energy capture and charge-transport properties.
Abstract: In natural photosynthesis, organisms optimize solar energy conversion through organized assemblies of photofunctional chromophores and catalysts within proteins that provide specifically tailored environments for chemical reactions. As with their natural counterparts, artificial photosynthetic systems for practical solar fuels production must collect light energy, separate charge, and transport charge to catalytic sites where multielectron redox processes will occur. While encouraging progress has been made on each aspect of this complex problem, researchers have not yet developed self-ordering and self-assembling components and the tailored environments necessary to realize a fully-functional artificial system. Previously researchers have used complex, covalent molecular systems comprised of chromophores, electron donors, and electron acceptors to mimic both the light-harvesting and the charge separation functions of photosynthetic proteins. These systems allow for study of the dependencies of electron t...
TL;DR: It is reported that both the rate-limiting enzyme in mammalian Nicotinamide adenine dinucleotide (NAD+) biosynthesis, nicotinamide phosphoribosyltransferase (NAMPT), and levels of NAD+ display circadian oscillations that are regulated by the core clock machinery in mice.
Abstract: The circadian clock is encoded by a transcription-translation feedback loop that synchronizes behavior and metabolism with the light-dark cycle. Here we report that both the rate-limiting enzyme in mammalian nicotinamide adenine dinucleotide (NAD+) biosynthesis, nicotinamide phosphoribosyltransferase (NAMPT), and levels of NAD+ display circadian oscillations that are regulated by the core clock machinery in mice. Inhibition of NAMPT promotes oscillation of the clock gene Per2 by releasing CLOCK:BMAL1 from suppression by SIRT1. In turn, the circadian transcription factor CLOCK binds to and up-regulates Nampt, thus completing a feedback loop involving NAMPT/NAD+ and SIRT1/CLOCK:BMAL1.
TL;DR: In this paper, the authors present theoretical and empirical motivation for a learning progression for scientific modeling that aims to make the practice accessible and meaningful for learners, including the elements of the practice (constructing, using, evaluating, and revising scientific models) and the metaknowledge that guides and motivates the practice.
Abstract: Modeling is a core practice in science and a central part of scientific literacy. We present theoretical and empirical motivation for a learning progression for scientific modeling that aims to make the practice accessible and meaningful for learners. We define scientific modeling as including the elements of the practice (constructing, using, evaluating, and revising scientific models) and the metaknowledge that guides and motivates the practice (e.g., understanding the nature and purpose of models). Our learning progression for scientific modeling includes two dimensions that combine metaknowledge and elements of practice—scientific models as tools for predicting and explaining, and models change as understanding improves. We describe levels of progress along these two dimensions of our progression and illustrate them with classroom examples from 5th and 6th graders engaged in modeling. Our illustrations indicate that both groups of learners productively engaged in constructing and revising increasingly accurate models that included powerful explanatory mechanisms, and applied these models to make predictions for closely related phenomena. Furthermore, we show how students engaged in modeling practices move along levels of this progression. In particular, students moved from illustrative to explanatory models, and developed increasingly sophisticated views of the explanatory nature of models, shifting from models as correct or incorrect to models as encompassing explanations for multiple aspects of a target phenomenon. They also developed more nuanced reasons to revise models. Finally, we present challenges for learners in modeling practices—such as understanding how constructing a model can aid their own sensemaking, and seeing model building as a way to generate new knowledge rather than represent what they have already learned. 2009 Wiley Periodicals, Inc. J Res Sci Teach 46: 632-654, 2009