Showing papers by "Dartmouth College published in 2003"

Open Innovation: The New Imperative for Creating and Profiting from Technology

Abstract: The article reviews the book “Open Innovation: The New Imperative for Creating and Profiting From Technology,” by Henry Chesbrough.

The dynamic resource-based view: capability lifecycles

Abstract: This article introduces the concept of the capability lifecycle (CLC), which articulates general patterns and paths in the evolution of organizational capabilities over time. The capability lifecycle provides a structure for a more comprehensive approach to dynamic resource-based theory. The analysis incorporates the founding, development, and maturity of capabilities in a manner that helps to explain the sources of heterogeneity in organizational capabilities. In addition, the analysis includes the ‘branching’ of an original capability into several possible altered forms. Copyright © 2003 John Wiley & Sons, Ltd.

Plants and Productivity in International Trade

Abstract: We reconcile trade theory with plant-level export behavior, extending the Ricardian model to accommodate many countries, geographic barriers, and imperfect competition. Our model captures qualitatively basic facts about U.S. plants: (i) productivity dispersion, (ii) higher productivity among exporters, (iii) the small fraction who export, (iv) the small fraction earned from exports among exporting plants, and (v) the size advantage of exporters. Fitting the model to bilateral trade among the United States and 46 major trade partners, we examine the impact of globalization and dollar appreciation on productivity, plant entry and exit, and labor turnover in U.S. manufacturing. (JEL F11, F17, O33)

Phantom Energy: Dark Energy with w< 1 Causes a Cosmic Doomsday

Abstract: We explore the consequences that follow if the dark energy is phantom energy, in which the sum of the pressure and energy density is negative. The positive phantom-energy density becomes infinite in finite time, overcoming all other forms of matter, such that the gravitational repulsion rapidly brings our brief epoch of cosmic structure to a close. The phantom energy rips apart the Milky Way, solar system, Earth, and ultimately the molecules, atoms, nuclei, and nucleons of which we are composed, before the death of the Universe in a "big rip."

A uniform system for microRNA annotation

Abstract: MicroRNAs (miRNAs) are small noncoding RNA gene products about 22 nt long that are processed by Dicer from precursors with a characteristic hairpin secondary structure. Guidelines are presented for the identification and annotation of new miRNAs from diverse organisms, particularly so that miRNAs can be reliably distinguished from other RNAs such as small interfering RNAs. We describe specific criteria for the experimental verification of miRNAs, and conventions for naming miRNAs and miRNA genes. Finally, an online clearinghouse for miRNA gene name assignments is provided by the Rfam database of RNA families.

Role of MicroRNAs in Plant and Animal Development

Abstract: Small RNAs, including microRNAs (miRNAs) and short interfering RNAs (siRNAs), are key components of an evolutionarily conserved system of RNA-based gene regulation in eukaryotes. They are involved in many molecular interactions, including defense against viruses and regulation of gene expression during development. miRNAs interfere with expression of messenger RNAs encoding factors that control developmental timing, stem cell maintenance, and other developmental and physiological processes in plants and animals. miRNAs are negative regulators that function as specificity determinants, or guides, within complexes that inhibit protein synthesis (animals) or promote degradation (plants) of mRNA targets.

Brand Synthesis: The Multidimensionality of Brand Knowledge

Abstract: The increased priority placed on branding by marketers in recent years offers an opportunity for consumer researchers to provide valuable insights and guidance. In particular, in highly competitive marketplaces, marketers often must link their brands to other entities, for example, people, places, things, or other brands, as a means to improve their brand equity. Understanding this leveraging process requires understanding consumer brand knowledge and how it changes from such associations. In this essay, I identify some promising and productive current research on this topic, and I suggest some important issues for future research. I conclude that adopting broader, more holistic perspectives that synthesize the multidimensionality of brand knowledge is critical to advance branding theory and practice, both in general and with brand leveraging in particular.

The genome sequence of the filamentous fungus Neurospora crassa

Abstract: Neurospora crassa is a central organism in the history of twentieth-century genetics, biochemistry and molecular biology. Here, we report a high-quality draft sequence of the N. crassa genome. The approximately 40-megabase genome encodes about 10,000 protein-coding genes—more than twice as many as in the fission yeast Schizosaccharomyces pombe and only about 25% fewer than in the fruitfly Drosophila melanogaster. Analysis of the gene set yields insights into unexpected aspects of Neurospora biology including the identification of genes potentially associated with red light photobiology, genes implicated in secondary metabolism, and important differences in Ca21 signalling as compared with plants and animals. Neurospora possesses the widest array of genome defence mechanisms known for any eukaryotic organism, including a process unique to fungi called repeat-induced point mutation (RIP). Genome analysis suggests that RIP has had a profound impact on genome evolution, greatly slowing the creation of new genes through genomic duplication and resulting in a genome with an unusually low proportion of closely related genes.

The Implications of Regional Variations in Medicare Spending. Part 1: The Content, Quality, and Accessibility of Care

Abstract: The more inpatient-based and specialist-oriented pattern of practice observed in high-spending regions largely explains regional differences in Medicare spending. Neither quality of care nor access...

Unraveling the resource-based tangle

Abstract: Resource-based theory (RBT) is a prime example of a theory that integrates a management perspective with an economics perspective. As such, its challenge is to keep its arguments logically consistent and clear, despite the risk of their becoming entangled, due to competing and possibly conflicting theoretical influences. We argue, in this paper, that to meet this challenge, it is essential to understand the limits to the domain of RBT. Unless RBT is understood as a resource-level and efficiency-oriented analytical tool, its contribution cannot be understood and appreciated fully. Incorporating aspects of economic theory that fall outside this domain will not increase its power and will only add to the confusion. Continued efforts to increase the analytic precision of RBT and to elaborate its economic logic, however, are worthwhile pursuits. To these aims, then, we provide a sharper definition of competitive advantage, linking this term to value creation and to demand side concerns. Similarly, we provide an economically meaningful definition of value and more precise definitions of critical resources and of economic rents. This allows us to trace a clearer trail of logic, consistent with both the management and the economics perspectives, leading from critical resources to the generation of rents. Copyright © 2003 John Wiley & Sons, Ltd.

The Implications of Regional Variations in Medicare Spending. Part 2: Health Outcomes and Satisfaction with Care

Abstract: Background The health implications of regional differences in Medicare spending are unknown. Objective To determine whether regions with higher Medicare spending achieve better survival, functional status, or satisfaction with care. Design Cohort study. Setting National study of Medicare beneficiaries. Patients Patients hospitalized between 1993 and 1995 for hip fracture (n = 614,503), colorectal cancer (n = 195,429), or acute myocardial infarction (n = 159,393) and a representative sample (n = 18,190) drawn from the Medicare Current Beneficiary Survey (MCBS) (1992-1995). EXPOSURE MEASUREMENT: End-of-life spending reflects the component of regional variation in Medicare spending that is unrelated to regional differences in illness. Each cohort member's exposure to different levels of spending was therefore defined by the level of end-of-life spending in his or her hospital referral region of residence (n = 306). Outcome measurements 5-year mortality rate (all four cohorts), change in functional status (MCBS cohort), and satisfaction (MCBS cohort). Results Cohort members were similar in baseline health status, but those in regions with higher end-of-life spending received 60% more care. Each 10% increase in regional end-of-life spending was associated with the following relative risks for death: hip fracture cohort, 1.003 (95% CI, 0.999 to 1.006); colorectal cancer cohort, 1.012 (CI, 1.004 to 1.019); acute myocardial infarction cohort, 1.007 (CI, 1.001 to 1.014); and MCBS cohort, 1.01 (CI, 0.99 to 1.03). There were no differences in the rate of decline in functional status across spending levels and no consistent differences in satisfaction. Conclusions Medicare enrollees in higher-spending regions receive more care than those in lower-spending regions but do not have better health outcomes or satisfaction with care. Efforts to reduce spending should proceed with caution, but policies to better manage further spending growth are warranted.

A randomized trial of aspirin to prevent colorectal adenomas

Abstract: Background Laboratory and epidemiologic data suggest that aspirin has an antineoplastic effect in the large bowel. Methods We performed a randomized, double-blind trial of aspirin as a chemopreventive agent against colorectal adenomas. We randomly assigned 1121 patients with a recent history of histologically documented adenomas to receive placebo (372 patients), 81 mg of aspirin (377 patients), or 325 mg of aspirin (372 patients) daily. According to the protocol, follow-up colonoscopy was to be performed approximately three years after the qualifying endoscopy. We compared the groups with respect to the risk of one or more neoplasms (adenomas or colorectal cancer) at least one year after randomization using generalized linear models to compute risk ratios and 95 percent confidence intervals. Results Reported adherence to study medications and avoidance of nonsteroidal antiinflammatory drugs were excellent. Follow-up colonoscopy was performed at least one year after randomization in 1084 patients (97 perc...

Corporate effects and dynamic managerial capabilities

Abstract: Corporate effects in variance decomposition capture heterogeneity of business performance derived from factors internal to firms at the corporate level. Most estimates of corporate effects do not include effects associated with fluctuations in returns over time, except insofar as the fluctuations affect the average corporate return for the time period in question. Exclusion of the time-varying dimension of the corporate effect makes it difficult to fully understand the effect of corporate strategy and the actions of corporate managers, particularly in response to a changing environment. The evidence in this article shows that within a single industry, where managers face the same external environment, time-varying corporate effects associated with corporate level managerial decisions are statistically significant. We introduce the concept of dynamic managerial capabilities to underpin the finding of heterogeneity in managerial decisions and firm performance in the face of changing external conditions. Copyright © 2003 John Wiley & Sons, Ltd.

Individual and combined effects of age, breast density, and hormone replacement therapy use on the accuracy of screening mammography.

Abstract: Mammographic breast density and age are important predictors of the accuracy of screening mammography. Although use of hormone replacement therapy is not an independent predictor of accuracy, it pr...

A randomized trial of aspirin to prevent colorectal adenomas in patients with previous colorectal cancer.

Abstract: Background Experimental studies in animals and observational studies in humans suggest that regular aspirin use may decrease the risk of colorectal adenomas, the precursors to most colorectal cancers. Methods We conducted a randomized, double-blind trial to determine the effect of aspirin on the incidence of colorectal adenomas. We randomly assigned 635 patients with previous colorectal cancer to receive either 325 mg of aspirin per day or placebo. We determined the proportion of patients with adenomas, the number of recurrent adenomas, and the time to the development of adenoma between randomization and subsequent colonoscopic examinations. Relative risks were adjusted for age, sex, cancer stage, the number of colonoscopic examinations, and the time to a first colonoscopy. The study was terminated early by an independent data and safety monitoring board when statistically significant results were reported during a planned interim analysis. Results A total of 517 randomized patients had at least one colon...

A genetic basis for Pseudomonas aeruginosa biofilm antibiotic resistance

Abstract: Biofilms are surface-attached microbial communities with characteristic architecture and phenotypic and biochemical properties distinct from their free-swimming, planktonic counterparts. One of the best-known of these biofilm-specific properties is the development of antibiotic resistance that can be up to 1,000-fold greater than planktonic cells. We report a genetic determinant of this high-level resistance in the Gram-negative opportunistic pathogen, Pseudomonas aeruginosa. We have identified a mutant of P. aeruginosa that, while still capable of forming biofilms with the characteristic P. aeruginosa architecture, does not develop high-level biofilm-specific resistance to three different classes of antibiotics. The locus identified in our screen, ndvB, is required for the synthesis of periplasmic glucans. Our discovery that these periplasmic glucans interact physically with tobramycin suggests that these glucose polymers may prevent antibiotics from reaching their sites of action by sequestering these antimicrobial agents in the periplasm. Our results indicate that biofilms themselves are not simply a diffusion barrier to these antibiotics, but rather that bacteria within these microbial communities employ distinct mechanisms to resist the action of antimicrobial agents.

Revenue Premium as an Outcome Measure of Brand Equity

Abstract: The authors propose that the revenue premium a brand generates compared with that of a private label product is a simple, objective, and managerially useful product-market measure of brand equity. The authors provide the conceptual basis for the measure, compute it for brands in several packaged goods categories, and test its validity. The empirical analysis shows that the measure is reliable and reflects real changes in brand health over time. It correlates well with other equity measures, and the measure’s association with a brand’s advertising and promotion activity, price sensitivity, and perceived category risk is consistent with theory.

Basic principles of thermal dosimetry and thermal thresholds for tissue damage from hyperthermia

Abstract: This paper is one of several in this Special Issue of the International Journal of Hyperthermia that discusses the current state of knowledge about the human health risks of hyperthermia This special issue emanated from a workshop sponsored by the World Health Organization in the Spring of 2002 on this topic It is anticipated that these papers will help to establish guidelines for human exposure to conditions leading to hyperthermia This comprehensive review of the literature makes it clear that much more work needs to be done to clarify what the thresholds for thermal damage are in humans This review summarizes the basic principles that govern the relationships between thermal exposure (temperature and time of exposure) and thermal damage, with an emphasis on normal tissue effects Methods for converting one time-temperature combination to a time at a standardized temperature are provided as well as a detailed discussion about the underlying assumptions that go into these calculations There are few in vivo papers examining the type and extent of damage that occurs in the lower temperature range for hyperthermic exposures (eg 39-42 degrees C) Therefore, it is clear that estimation of thermal dose to effect at these thermal exposures is less precise in that temperature range In addition, there are virtually no data that directly relate to the thermal sensitivity of human tissues Thus, establishment of guidelines for human exposure based on the data provided must be done with significant caution There is detailed review and presentation of thermal thresholds for tissue damage (based on what is detectable in vivo) The data are normalized using thermal dosimetric concepts Tables are included in an Appendix Database which compile published data for thresholds of thermal damage in a variety of tissues and species This database is available by request (contact MWD or PJH), but not included in this manuscript for brevity All of the studies reported are for single acute thermal exposures Except for brain function and physiology (as detailed in this issue by Sharma et al) one notes the critical lack of publications examining effects of chronic thermal exposures as might be encountered in occupational hazards This review also does not include information on the embryo, which is covered in detail elsewhere in this volume (see article by Edwards et al) as well as in a recent review on this subject, which focuses on thermal dose

Links between erosion, runoff variability and seismicity in the Taiwan orogen

Abstract: The erosion of mountain belts controls their topographic and structural evolution1,2,3 and is the main source of sediment delivered to the oceans4 Mountain erosion rates have been estimated from current relief and precipitation, but a more complete evaluation of the controls on erosion rates requires detailed measurements across a range of timescales Here we report erosion rates in the Taiwan mountains estimated from modern river sediment loads, Holocene river incision and thermochronometry on a million-year scale Estimated erosion rates within the actively deforming mountains are high (3–6 mm yr-1) on all timescales, but the pattern of erosion has changed over time in response to the migration of localized tectonic deformation Modern, decadal-scale erosion rates correlate with historical seismicity and storm-driven runoff variability The highest erosion rates are found where rapid deformation, high storm frequency and weak substrates coincide, despite low topographic relief

Breathing: Rhythmicity, plasticity, chemosensitivity

Abstract: ▪ Abstract Breathing is a vital behavior that is particularly amenable to experimental investigation. We review recent progress on three problems of broad interest. (i) Where and how is respiratory rhythm generated? The preBotzinger Complex is a critical site, whereas pacemaker neurons may not be essential. The possibility that coupled oscillators are involved is considered. (ii) What are the mechanisms that underlie the plasticity necessary for adaptive changes in breathing? Serotonin-dependent long-term facilitation following intermittent hypoxia is an important example of such plasticity, and a model that can account for this adaptive behavior is discussed. (iii) Where and how are the regulated variables CO2 and pH sensed? These sensors are essential if breathing is to be appropriate for metabolism. Neurons with appropriate chemosensitivity are spread throughout the brainstem; their individual properties and collective role are just beginning to be understood.

Inhibition of Microglial Activation Attenuates the Development but not Existing Hypersensitivity in a Rat Model of Neuropathy

Abstract: Microglia, the intrinsic macrophages of the central nervous system, have previously been shown to be activated in the spinal cord in several rat mononeuropathy models. Activation of microglia and subsequent release of proinflammatory cytokines are known to play a role in inducing a behavioral hypersensitive state (hyperalgesia and allodynia) in these animals. The present study was undertaken to determine whether minocycline, an inhibitor of microglial activation, could attenuate both the development and existing mechanical allodynia and hyperalgesia in an L5 spinal nerve transection model of neuropathic pain. In a preventive paradigm (to study the effect on the development of hypersensitive behaviors), minocycline (10, 20, or 40 mg/kg intraperitoneally) was administered daily, beginning 1 h before nerve transection. This regimen produced a decrease in mechanical hyperalgesia and allodynia, with a maximum inhibitory effect observed at the dose of 20 and 40 mg/kg. The attenuation of the development of hyperalgesia and allodynia by minocycline was associated with an inhibitory action on microglial activation and suppression of proinflammatory cytokines at the L5 lumbar spinal cord of the nerveinjured animals. The effect of minocycline on existing allodynia was examined after its intraperitoneal administration initiated on day 5 post-L5 nerve transection. Although the postinjury administration of minocycline significantly inhibited microglial activation in neuropathic rats, it failed to attenuate existing hyperalgesia and allodynia. These data demonstrate that inhibition of microglial activation attenuated the development of behavioral hypersensitivity in a rat model of neuropathic pain but had no effect on the treatment of existing mechanical allodynia and hyperalgesia.

What Works in Securities Laws

Abstract: We examine the effect of securities laws on stock market development in 49 countries. We find almost no evidence that public enforcement benefits stock markets, and strong evidence that laws facilitating private enforcement through disclosure and liability rules benefit stock markets.

Rhamnolipid surfactant production affects biofilm architecture in Pseudomonas aeruginosa PAO1.

Abstract: In response to certain environmental signals, bacteria will differentiate from an independent free-living mode of growth and take up an interdependent surface-attached existence. These surface-attached microbial communities are known as biofilms. In flowing systems where nutrients are available, biofilms can develop into elaborate three-dimensional structures. The development of biofilm architecture, particularly the spatial arrangement of colonies within the matrix and the open areas surrounding the colonies, is thought to be fundamental to the function of these complex communities. Here we report a new role for rhamnolipid surfactants produced by the opportunistic pathogen Pseudomonas aeruginosa in the maintenance of biofilm architecture. Biofilms produced by mutants deficient in rhamnolipid synthesis do not maintain the noncolonized channels surrounding macrocolonies. We provide evidence that surfactants may be able to maintain open channels by affecting cell-cell interactions and the attachment of bacterial cells to surfaces. The induced synthesis of rhamnolipids during the later stages of biofilm development (when cell density is high) implies an active mechanism whereby the bacteria exploit intercellular interaction and communication to actively maintain these channels. We propose that the maintenance of biofilm architecture represents a previously unrecognized step in the development of these microbial communities.

Angiogenic synergism, vascular stability and improvement of hind-limb ischemia by a combination of PDGF-BB and FGF-2

Abstract: The establishment of functional and stable vascular networks is essential for angiogenic therapy. Here we report that a combination of two angiogenic factors, platelet-derived growth factor (PDGF)-BB and fibroblast growth factor (FGF)-2, synergistically induces vascular networks, which remain stable for more than a year even after depletion of angiogenic factors. In both rat and rabbit ischemic hind limb models, PDGF-BB and FGF-2 together markedly stimulated collateral arteriogenesis after ligation of the femoral artery, with a significant increase in vascularization and improvement in paw blood flow. A possible mechanism of angiogenic synergism between PDGF-BB and FGF-2 involves upregulation of the expression of PDGF receptor (PDGFR)-alpha and PDGFR-beta by FGF-2 in newly formed blood vessels. Our data show that a specific combination of angiogenic factors establishes functional and stable vascular networks, and provides guidance for the ongoing clinical trials of angiogenic factors for the treatment of ischemic diseases.

Brand Familiarity and Advertising Repetition Effects

Abstract: A crucial communication task for unknown brands is to build the knowledge in consumers' minds necessary to become established. However, communication effectiveness may depend on prior familiarity of the advertised brand. The findings of two experiments using television ads and computer Internet ads revealed that brand familiarity influenced repetition effectiveness. In particular, repetition of advertising attributed to an unfamiliar brand showed decreased effectiveness; when the same advertising was attributed to a known, familiar brand, repetition wearout was postponed. Negative thoughts about tactic inappropriateness were seen to arise with repetition, particularly for an ad for an unfamiliar brand, driving, in part, the decreases in repetition effectiveness.