Showing papers by "Dartmouth College published in 2009"

Effects of Word-of-Mouth Versus Traditional Marketing: Findings from an Internet Social Networking Site

Abstract: The authors study the effect of word-of-mouth (WOM) marketing on member growth at an Internet social networking site and compare it with traditional marketing vehicles. Because social network sites record the electronic invitations from existing members, outbound WOM can be precisely tracked. Along with traditional marketing, WOM can then be linked to the number of new members subsequently joining the site (sign-ups). Because of the endogeneity among WOM, new sign-ups, and traditional marketing activity, the authors employ a vector autoregressive (VAR) modeling approach. Estimates from the VAR model show that WOM referrals have substantially longer carryover effects than traditional marketing actions and produce substantially higher response elasticities. Based on revenue from advertising impressions served to a new member, the monetary value of a WOM referral can be calculated; this yields an upper-bound estimate for the financial incentives the firm might offer to stimulate WOM.

Sinking deltas due to human activities

Abstract: Many of the world's deltas are densely populated and intensively farmed. An assessment of recent publications indicates that the majority of these deltas have been subject to intense flooding over the past decade, and that this threat will grow as global sea-level rises and as the deltas subside. Many of the world's largest deltas are densely populated and heavily farmed. Yet many of their inhabitants are becoming increasingly vulnerable to flooding and conversions of their land to open ocean. The vulnerability is a result of sediment compaction from the removal of oil, gas and water from the delta's underlying sediments, the trapping of sediment in reservoirs upstream and floodplain engineering in combination with rising global sea level. Here we present an assessment of 33 deltas chosen to represent the world's deltas. We find that in the past decade, 85% of the deltas experienced severe flooding, resulting in the temporary submergence of 260,000 km2. We conservatively estimate that the delta surface area vulnerable to flooding could increase by 50% under the current projected values for sea-level rise in the twenty-first century. This figure could increase if the capture of sediment upstream persists and continues to prevent the growth and buffering of the deltas.

Osteosarcoma incidence and survival rates from 1973 to 2004: Data from the Surveillance, Epidemiology, and End Results Program

Abstract: Background Osteosarcoma, the most common primary bone tumor, occurs most frequently in adolescents, but a second incidence peak among individuals over age 60 exists. Most osteosarcoma epidemiology studies have been embedded in large analyses of all bone tumors, or focused on cases occurring in adolescence. Detailed descriptions of osteosarcoma incidence and survival specifically, with direct comparisons among subjects of all ages and ethnicities, are not available.

Value Creation in Innovation Ecosystems: How the Structure of Technological Interdependence Affects Firm Performance in New Technology Generations

Abstract: The success of an innovating firm often depends on the efforts of other innovators in its environment. How do the challenges faced by external innovators affect the focal firm's outcomes? To address this question we first characterize the external environment according to the structure of interdependence. We follow the flow of inputs and outputs in the ecosystem to distinguish between upstream components that are bundled by the focal firm, and downstream complements that are bundled by the firm's customers. We argue that the effect of external innovation challenges depends not only on their magnitude, but also on their location in the ecosystem relative to the focal firm - whereas greater innovation challenges in components enhances the benefits that accrue to technology leaders, greater innovation challenges in complements erodes these benefits. We further argue that the effectiveness of vertical integration as a strategy to manage ecosystem interdependence increases over the course of the technology life cycle. We explore these arguments in the context of the global semiconductor lithography industry from its emergence in 1962 to 2005 across nine distinct technology generations. We find strong support for our arguments.

Beneficial Biofuels—The Food, Energy, and Environment Trilemma

Abstract: Recent analyses of the energy and greenhouse-gas performance of alternative biofuels have ignited a controversy that may be best resolved by applying two simple principles. In a world seeking solutions to its energy, environmental, and food challenges, society cannot afford to miss out on the global greenhouse-gas emission reductions and the local environmental and societal benefits when biofuels are done right. However, society also cannot accept the undesirable impacts of biofuels done wrong.

Screening for Breast Cancer: US Preventive Services Task Force Recommendation Statement

Abstract: Description: Update of the 2002 U. S. Preventive Services Task Force (USPSTF) recommendation statement on screening for breast cancer in the general population. Methods: The USPSTF examined the evidence on the efficacy of 5 screening modalities in reducing mortality from breast cancer: film mammography, clinical breast examination, breast self-examination, digital mammography, and magnetic resonance imaging in order to update the 2002 recommendation. To accomplish this update, the USPSTF commissioned 2 studies: 1) a targeted systematic evidence review of 6 selected questions relating to benefits and harms of screening, and 2) a decision analysis that used population modeling techniques to compare the expected health outcomes and resource requirements of starting and ending mammography screening at different ages and using annual versus biennial screening intervals. Recommendations: The USPSTF recommends against routine screening mammography in women aged 40 to 49 years. The decision to start regular, biennial screening mammography before the age of 50 years should be an individual one and take into account patient context, including the patient's values regarding specific benefits and harms. (Grade C recommendation) The USPSTF recommends biennial screening mammography for women between the ages of 50 and 74 years. (Grade B recommendation) The USPSTF concludes that the current evidence is insufficient to assess the additional benefits and harms of screening mammography in women 75 years or older. (I statement) The USPSTF concludes that the current evidence is insufficient to assess the additional benefits and harms of clinical breast examination beyond screening mammography in women 40 years or older. (I statement) The USPSTF recommends against clinicians teaching women how to perform breast self-examination. (Grade D recommendation) The USPSTF concludes that the current evidence is insufficient to assess additional benefits and harms of either digital mammography or magnetic resonance imaging instead of film mammography as screening modalities for breast cancer. (I statement)

The Genetic Structure and History of Africans and African Americans

Abstract: Africa is the source of all modern humans, but characterization of genetic variation and of relationships among populations across the continent has been enigmatic. We studied 121 African populations, four African American populations, and 60 non-African populations for patterns of variation at 1327 nuclear microsatellite and insertion/deletion markers. We identified 14 ancestral population clusters in Africa that correlate with self-described ethnicity and shared cultural and/or linguistic properties. We observed high levels of mixed ancestry in most populations, reflecting historical migration events across the continent. Our data also provide evidence for shared ancestry among geographically diverse hunter-gatherer populations (Khoesan speakers and Pygmies). The ancestry of African Americans is predominantly from Niger-Kordofanian (approximately 71%), European (approximately 13%), and other African (approximately 8%) populations, although admixture levels varied considerably among individuals. This study helps tease apart the complex evolutionary history of Africans and African Americans, aiding both anthropological and genetic epidemiologic studies.

Presidents and Assemblies: Constitutional Design and Electoral Dynamics

Abstract: Part I. Presidential and Parliamentary Democracy: 1. Basic choices in democratic regime types 2. What is presidentialism? Criticisms and responses 3. The constitutional origin and survival of assembly and executive 4. Legislative powers of presidents: veto and decree Part II. Electoral Dynamics of Presidential Democracy: 5. Electoral dynamics: efficiency and inefficiency 6. Electoral rules and the party system 7. Electoral cycles and the party system Part III. Institutiona: Engineering: 8. Semi-presidentialism: the third alternative 9. Electoral cycles in semi-presidential regimes 10. Divided polities and collegial presidencies 11. Conclusions Appendices.

Radiofrequency Ablation in Barrett's Esophagus with Dysplasia

Abstract: Background Barrett’s esophagus, a condition of intestinal metaplasia of the esophagus, is associated with an increased risk of esophageal adenocarcinoma. We assessed whether endoscopic radiofrequency ablation could eradicate dysplastic Barrett’s esophagus and decrease the rate of neoplastic progression. Methods In a multicenter, sham-controlled trial, we randomly assigned 127 patients with dysplastic Barrett’s esophagus in a 2:1 ratio to receive either radiofrequency ablation (ablation group) or a sham procedure (control group). Randomization was stratified according to the grade of dysplasia and the length of Barrett’s esophagus. Primary outcomes at 12 months included the complete eradication of dysplasia and intestinal metaplasia. Results In the intention-to-treat analyses, among patients with low-grade dysplasia, complete eradication of dysplasia occurred in 90.5% of those in the ablation group, as compared with 22.7% of those in the control group (P<0.001). Among patients with highgrade dysplasia, complete eradication occurred in 81.0% of those in the ablation group, as compared with 19.0% of those in the control group (P<0.001). Overall, 77.4% of patients in the ablation group had complete eradication of intestinal metaplasia, as compared with 2.3% of those in the control group (P<0.001). Patients in the ablation group had less disease progression (3.6% vs. 16.3%, P = 0.03) and fewer cancers (1.2% vs. 9.3%, P = 0.045). Patients reported having more chest pain after the ablation procedure than after the sham procedure. In the ablation group, one patient had upper gastrointestinal hemorrhage, and five patients (6.0%) had esophageal stricture. Conclusions In patients with dysplastic Barrett’s esophagus, radiofrequency ablation was associated with a high rate of complete eradication of both dysplasia and intestinal metaplasia and a reduced risk of disease progression. (ClinicalTrials.gov number, NCT00282672.)

Molecular mechanism and function of CD40/CD40L engagement in the immune system.

Abstract: During the generation of a successful adaptive immune response, multiple molecular signals are required. A primary signal is the binding of cognate antigen to an antigen receptor expressed by T and B lymphocytes. Multiple secondary signals involve the engagement of costimulatory molecules expressed by T and B lymphocytes with their respective ligands. Because of its essential role in immunity, one of the best characterized of the costimulatory molecules is the receptor CD40. This receptor, a member of the tumor necrosis factor receptor family, is expressed by B cells, professional antigen-presenting cells, as well as non-immune cells and tumors. CD40 binds its ligand CD40L, which is transiently expressed on T cells and other non-immune cells under inflammatory conditions. A wide spectrum of molecular and cellular processes is regulated by CD40 engagement including the initiation and progression of cellular and humoral adaptive immunity. In this review, we describe the downstream signaling pathways initiated by CD40 and overview how CD40 engagement or antagonism modulates humoral and cellular immunity. Lastly, we discuss the role of CD40 as a target in harnessing anti-tumor immunity. This review underscores the essential role CD40 plays in adaptive immunity.

Seaweed Extracts as Biostimulants of Plant Growth and Development

Abstract: Marine algal seaweed species are often regarded as an underutilized bioresource, many have been used as a source of food, industrial raw materials, and in therapeutic and botanical applications for centuries. Moreover, seaweed and seaweed-derived products have been widely used as amendments in crop production systems due to the presence of a number of plant growth-stimulating compounds. However, the biostimulatory potential of many of these products has not been fully exploited due to the lack of scientific data on growth factors present in seaweeds and their mode of action in affecting plant growth. This article provides a comprehensive review of the effect of various seaweed species and seaweed products on plant growth and development with an emphasis on the use of this renewable bioresource in sustainable agricultural systems.

Aging and Environmental Exposures Alter Tissue-Specific DNA Methylation Dependent upon CpG Island Context

Abstract: Epigenetic control of gene transcription is critical for normal human development and cellular differentiation. While alterations of epigenetic marks such as DNA methylation have been linked to cancers and many other human diseases, interindividual epigenetic variations in normal tissues due to aging, environmental factors, or innate susceptibility are poorly characterized. The plasticity, tissue-specific nature, and variability of gene expression are related to epigenomic states that vary across individuals. Thus, population-based investigations are needed to further our understanding of the fundamental dynamics of normal individual epigenomes. We analyzed 217 non-pathologic human tissues from 10 anatomic sites at 1,413 autosomal CpG loci associated with 773 genes to investigate tissue-specific differences in DNA methylation and to discern how aging and exposures contribute to normal variation in methylation. Methylation profile classes derived from unsupervised modeling were significantly associated with age (P<0.0001) and were significant predictors of tissue origin (P<0.0001). In solid tissues (n = 119) we found striking, highly significant CpG island-dependent correlations between age and methylation; loci in CpG islands gained methylation with age, loci not in CpG islands lost methylation with age (P<0.001), and this pattern was consistent across tissues and in an analysis of blood-derived DNA. Our data clearly demonstrate age- and exposure-related differences in tissue-specific methylation and significant age-associated methylation patterns which are CpG island context-dependent. This work provides novel insight into the role of aging and the environment in susceptibility to diseases such as cancer and critically informs the field of epigenomics by providing evidence of epigenetic dysregulation by age-related methylation alterations. Collectively we reveal key issues to consider both in the construction of reference and disease-related epigenomes and in the interpretation of potentially pathologically important alterations.

Runx1 is required for the endothelial to haematopoietic cell transition but not thereafter

Abstract: Haematopoietic stem cells (HSCs) are the founder cells of the adult haematopoietic system, and thus knowledge of the molecular program directing their generation during development is important for regenerative haematopoietic strategies. Runx1 is a pivotal transcription factor required for HSC generation in the vascular regions of the mouse conceptus-the aorta, vitelline and umbilical arteries, yolk sac and placenta. It is thought that HSCs emerge from vascular endothelial cells through the formation of intra-arterial clusters and that Runx1 functions during the transition from 'haemogenic endothelium' to HSCs. Here we show by conditional deletion that Runx1 activity in vascular-endothelial-cadherin-positive endothelial cells is indeed essential for intra-arterial cluster, haematopoietic progenitor and HSC formation in mice. In contrast, Runx1 is not required in cells expressing Vav1, one of the first pan-haematopoietic genes expressed in HSCs. Collectively these data show that Runx1 function is essential in endothelial cells for haematopoietic progenitor and HSC formation from the vasculature, but its requirement ends once or before Vav is expressed.

Horizontal Mergers, Collusion, and Stockholder Wealth

Abstract: This paper tests the hypothesis that horizontal mergers generate positive abnormal returns to stockholders of the bidder and target firms because they increase the probability of successful collusion among rival producers. Under the collusion hypothesis, rivals of the merging firms benefit from the merger since successful collusion limits output and raises product prices and/or lowers factor prices. This proposition is tested on a large sample of horizontal mergers in mining and manufacturing industries, including mergers challenged by the government with violating antitrust laws, and a "control" sample of vertical mergers taking place in the same industries. While we find that the antitrust law enforcement agencies systematically select relatively profitable mergers for prosecution, there is little evidence indicating that the mergers would have had collusive, anticompetitive effects.

Image forgery detection

Abstract: We are undoubtedly living in an age where we are exposed to a remarkable array of visual imagery. While we may have historically had confidence in the integrity of this imagery, today's digital technology has begun to erode this trust. From the tabloid magazines to the fashion industry and in mainstream media outlets, scientific journals, political campaigns, courtrooms, and the photo hoaxes that land in our e-mail in-boxes, doctored photographs are appearing with a growing frequency and sophistication. Over the past five years, the field of digital forensics has emerged to help restore some trust to digital images. The author reviews the state of the art in this new and exciting field.

Understanding dynamic capabilities: progress along a developmental path

Abstract: The aim of dynamic capabilities research is ambitious: to understand how firmscan sustain a competitive advantage by responding to and creating environmen-tal change (Teece, 2007). As one of the most central and difficult questionswithin the strategy domain, this might well be characterized as the Holy Grailof strategic management. The topical domain of dynamic capabilities, in conse-quence, is as broad and as complex as any in the field. It spans the domains ofstrategy process and content, and involves multiple levels of analysis, from man-agerial decision-processes, to organizational routines, to competitive inter-actions and environmental change. The complexity of the topic is matched,fittingly, by the complexity of the theoretical underpinnings. Undoubtedly, thishas generated some confusion. It is therefore not surprising that the critique ofArend and Bromiley (A&B) in the preceding essay reflects some of this confu-sion. Here, we address this by clarifying the dynamic capabilities concept, inrelation to its development and the challenges faced.We first survey the development path of dynamic capabilities research, anddiscuss the different theoretical bases of this emerging area of scholarship. Thenwe clarify issues regarding the definition of dynamic capabilities and discuss thelink between dynamic capabilities and firm performance. As part of our analy-sis, we address the two main conclusions of A&B regarding dynamic capabil-ities research. The first is that we should abandon the dynamic capabilitiesapproach if it does not ‘quickly develop a theoretical foundation’. The second isthat regardless of the pace of theory development, we should replace theseefforts with ‘work on strategic change tied to fuller theories of strategic organ-ization’. In what follows, we explain why these conclusions are premature andunwarranted. We also address other issues raised by A&B, focusing on the mainissues raised in the body of their commentary.

Global patterns of foliar nitrogen isotopes and their relationships with climate, mycorrhizal fungi, foliar nutrient concentrations, and nitrogen availability

Abstract: Ratios of nitrogen (N) isotopes in leaves could elucidate underlying patterns of N cycling across ecological gradients. To better understand global-scale patterns of N cycling, we compiled data on foliar N isotope ratios (delta(15)N), foliar N concentrations, mycorrhizal type and climate for over 11,000 plants worldwide. Arbuscular mycorrhizal, ectomycorrhizal, and ericoid mycorrhizal plants were depleted in foliar delta(15)N by 2 per thousand, 3.2 per thousand, 5.9 per thousand, respectively, relative to nonmycorrhizal plants. Foliar delta(15)N increased with decreasing mean annual precipitation and with increasing mean annual temperature (MAT) across sites with MAT >or= -0.5 degrees C, but was invariant with MAT across sites with MAT < -0.5 degrees C. In independent landscape-level to regional-level studies, foliar delta(15)N increased with increasing N availability; at the global scale, foliar delta(15)N increased with increasing foliar N concentrations and decreasing foliar phosphorus (P) concentrations. Together, these results suggest that warm, dry ecosystems have the highest N availability, while plants with high N concentrations, on average, occupy sites with higher N availability than plants with low N concentrations. Global-scale comparisons of other components of the N cycle are still required for better mechanistic understanding of the determinants of variation in foliar delta(15)N and ultimately global patterns in N cycling.

Arginase I–Producing Myeloid-Derived Suppressor Cells in Renal Cell Carcinoma Are a Subpopulation of Activated Granulocytes

Abstract: Myeloid-derived suppressor cells (MDSC) producing arginase I are increased in the peripheral blood of patients with renal cell carcinoma (RCC) MDSC inhibit T-cell function by reducing the availability of L-arginine and are therefore considered an important tumor escape mechanism We aimed to determine the origin of arginase I-producing MDSC in RCC patients and to identify the mechanisms used to deplete extracellular L-arginine The results show that human MDSC are a subpopulation of activated polymorphonuclear (PMN) cells expressing high levels of CD66b, CD11b, and VEGFR1 and low levels of CD62L and CD16 In contrast to murine MDSC, human MDSC do not deplete L-arginine by increasing its uptake but instead release arginase I into the circulation Activation of normal PMN induces phenotypic and functional changes similar to MDSC and also promotes the release of arginase I from intracellular granules Interestingly, although activation of normal PMN usually ends with apoptosis, MDSC showed no increase in apoptosis compared with autologous PMN or PMN obtained from normal controls High levels of VEGF have been shown to increase suppressor immature myeloid dendritic cells in cancer patients Treatment of RCC patients with anti-VEGF antibody bevacizumab, however, did not reduce the accumulation of MDSC in peripheral blood In contrast, the addition of interleukin-2 to the treatment increased the number of MDSC in peripheral blood and the plasma levels of arginase I These results may provide new insights on the mechanisms of tumor-induced anergy/tolerance and may help explain why some immunotherapies fail to induce an antitumor response

Building strong brands in a modern marketing communications environment

Abstract: To help marketers to build and manage their brands in a dramatically changing marketing communications environment, the customer-based brand equity model that emphasizes the importance of understanding consumer brand knowledge structures is put forth. Specifically, the brand resonance pyramid is reviewed as a means to track how marketing communications can create intense, active loyalty relationships and affect brand equity. According to this model, integrating marketing communications involves mixing and matching different communication options to establish the desired awareness and image in the minds of consumers. The versatility of on-line, interactive marketing communications to marketers in brand building is also addressed.

SoundSense: scalable sound sensing for people-centric applications on mobile phones

Abstract: Top end mobile phones include a number of specialized (e.g., accelerometer, compass, GPS) and general purpose sensors (e.g., microphone, camera) that enable new people-centric sensing applications. Perhaps the most ubiquitous and unexploited sensor on mobile phones is the microphone - a powerful sensor that is capable of making sophisticated inferences about human activity, location, and social events from sound. In this paper, we exploit this untapped sensor not in the context of human communications but as an enabler of new sensing applications. We propose SoundSense, a scalable framework for modeling sound events on mobile phones. SoundSense is implemented on the Apple iPhone and represents the first general purpose sound sensing system specifically designed to work on resource limited phones. The architecture and algorithms are designed for scalability and Soundsense uses a combination of supervised and unsupervised learning techniques to classify both general sound types (e.g., music, voice) and discover novel sound events specific to individual users. The system runs solely on the mobile phone with no back-end interactions. Through implementation and evaluation of two proof of concept people-centric sensing applications, we demostrate that SoundSense is capable of recognizing meaningful sound events that occur in users' everyday lives.

Near infrared optical tomography using nirfast: algorithm for numerical model and image reconstruction

Abstract: Diffuse optical tomography, also known as near infrared tomography, has been under investigation, for non-invasive functional imaging of tissue, specifically for the detection and characterization of breast cancer or other soft tissue lesions. Much work has been carried out for accurate modeling and image reconstruction from clinical data. NIRFAST, a modeling and image reconstruction package has been developed, which is capable of single wavelength and multi-wavelength optical or functional imaging from measured data. The theory behind the modeling techniques as well as the image reconstruction algorithms is presented here, and 2D and 3D examples are presented to demonstrate its capabilities. The results show that 3D modeling can be combined with measured data from multiple wavelengths to reconstruct chromophore concentrations within the tissue. Additionally it is possible to recover scattering spectra, resulting from the dominant Mie-type scatter present in tissue. Overall, this paper gives a comprehensive over view of the modeling techniques used in diffuse optical tomographic imaging, in the context of NIRFAST software package.

Aspirin and non-steroidal anti-inflammatory drugs for cancer prevention: an international consensus statement

Abstract: Evidence clearly shows a chemopreventive effect for aspirin and other non-steroidal anti-inflammatory drugs (NSAIDs) on colorectal cancer and probably other cancer types; however, data on the risk-benefit profile for cancer prevention are insufficient and no definitive recommendations can be made. Aspirin has emerged as the most likely NSAID for use in chemoprevention because of its known cardiovascular benefit and available safety and efficacy data. Other traditional NSAIDs, particularly sulindac, and selective COX-2 inhibitors are now given to patients at high risk of colorectal cancer, although these drugs do not provide cardioprotection. More studies of aspirin and cancer prevention are needed to define the lowest effective dose, the age at which to initiate therapy, the optimum treatment duration, and the subpopulations for which the benefits of chemoprevention outweigh the risks of adverse side-effects. Although it might be possible to answer some of these questions with longer follow-up of existing clinical trials, randomised controlled trials with new study designs will be needed. Future projects should investigate the effects of aspirin treatment on multiple organ systems. Cancers of interest are colorectal, breast, prostate, lung, stomach, and oesophageal. The main side-effect of aspirin is peptic ulcers; therefore coadministration of aspirin with a proton-pump inhibitor is an attractive option and is under investigation in the AspECT trial.

Exponential Growth Bias and Household Finance

Abstract: Exponential growth bias is the pervasive tendency to linearize exponential functions when assessing them intuitively. We show that exponential growth bias can explain two stylized facts in household finance: the tendency to underestimate an interest rate given other loan terms, and the tendency to underestimate a future value given other investment terms. Bias matters empirically: More-biased households borrow more, save less, favor shorter maturities, and use and benefit more from financial advice, conditional on a rich set of household characteristics. There is little evidence that our measure of exponential growth bias merely proxies for broader financial sophistication. WHAT DRIVES HOUSEHOLD financial decisions? The canonical economic model assumes that consumers choose to consume, borrow, or save based on their preferences, their expectations, and the costs and benefits of borrowing and saving. A growing body of work applies insights from psychology to enrich specifications of three of the model’s key pieces: preferences, expectations, and problem-solving conditional on parameter values. 1 In this paper, we bring psychological evidence to bear on a fourth specification issue: How consumers perceive the costs and benefits of borrowing and saving. We begin by tying together existing and new evidence on these cost perceptions to show that most consumers err systematically when given information commonly available in the market. On the saving side, consumers display future value bias: a systematic tendency to underestimate a future value given

Kalman-Consensus Filter : Optimality, stability, and performance

Abstract: One of the fundamental problems in sensor networks is to estimate and track the state of targets (or dynamic processes) of interest that evolve in the sensing field. Kalman filtering has been an effective algorithm for tracking dynamic processes for over four decades. Distributed Kalman Filtering (DKF) involves design of the information processing algorithm of a network of estimator agents with a two-fold objective: 1) estimate the state of the target of interest and 2) reach a consensus with neighboring estimator agents on the state estimate. We refer to this DKF algorithm as Kalman-Consensus Filter (KCF). The main contributions of this paper are as follows: i) finding the optimal decentralized Kalman-Consensus filter and showing that its computational and communication costs are not scalable in n and ii) introducing a scalable suboptimal Kalman-Consensus Filter and providing a formal stability and performance analysis of this distributed and cooperative filtering algorithm. Kalman-Consensus Filtering algorithm is applicable to sensor networks with variable topology including mobile sensor networks and networks with packet-loss.

Fast reconnection in high-Lundquist-number plasmas due to the plasmoid Instability

Abstract: Thin current sheets in systems of large size that exceed a critical value of the Lundquist number are unstable to a super-Alfvenic tearing instability, referred to hereafter as the plasmoid instability. The scaling of the growth rate of the most rapidly growing plasmoid instability with respect to the Lundquist number is shown to follow from the classical dispersion relation for tearing modes. As a result of this instability, the system realizes a nonlinear reconnection rate that appears to be weakly dependent on the Lundquist number, and larger than the Sweet–Parker rate by nearly an order of magnitude (for the range of Lundquist numbers considered). This regime of fast reconnection is realizable in a dynamic and highly unstable thin current sheet, without requiring the current sheet to be turbulent.

The expert consensus guideline series: adherence problems in patients with serious and persistent mental illness.

Abstract: Objectives Poor adherence to medication treatment can have devastating consequences for patients with mental illness. The goal of this project was to develop recommendations for addressing adherence problems to improve patient outcomes. Methods The editors identified important topics and questions concerning medication adherence problems in serious mental illness that are not fully addressed in the literature. A survey was developed containing 39 questions (521 options) asking about defining nonadherence, extent of adherence problems in schizophrenia and bipolar disorder, risk factors for nonadherence, assessment methods, and interventions for specific types of adherence problems. The survey was completed by 41 (85%) of the 48 experts to whom it was sent. Results of the literature review and survey were used to develop recommendations for assessing and improving adherence in patients with serious mental illness. Results ASSESSING ADHERENCE: The experts endorsed percentage of medication not taken as the preferred method of defining adherence, with 80% or more of medication taken endorsed as an appropriate cut-off for adherence in bipolar disorder and schizophrenia. Although self- and physician report are the most common methods used to assess adherence in clinical settings, they are often inaccurate and may underestimate nonadherence. The experts recommend that, if possible, clinicians also use more objective measures (e.g., pill counts, pharmacy records, and, when appropriate, serum levels such as are used for lithium). Use of a validated self-report scale may help improve accuracy. Scope of the problem The majority of the experts believed the average patient with schizophrenia or bipolar disorder in their practices takes only 51%-70% of prescribed medication. FACTORS ASSOCIATED WITH NONADHERENCE: The experts endorsed poor insight and lack of illness awareness, distress associated with specific side effects or a general fear of side effects, inadequate efficacy with persistent symptoms, and believing medications are no longer needed as the most important factors leading to adherence problems in schizophrenia and bipolar disorder. The experts considered weight gain a side effect that is very likely to lead to adherence problems in patients with schizophrenia and bipolar disorder; sedation was considered a more important contributor to adherence problems in bipolar disorder than schizophrenia. The experts rated persistent positive or negative symptoms in schizophrenia and persistent grandiosity and manic symptoms in bipolar disorder as the most important symptomatic contributors to adherence problems in these illnesses. Interventions It is important to identify the specific factors that may be contributing to a patient's adherence problems in order to customize interventions to target those problems. Multiple problems may be involved, requiring a combination of interventions. Conclusions Adherence problems are complex and multidetermined. The experts recommended customized interventions focused on the underlying causes.