2,022 research outputs found

    Taking Stock of the Digital Revolution: A Critical Analysis and Agenda for Digital, Social Media, and Mobile Marketing Research

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    Marketing has been revolutionized due to the rise of digital media and new forms of electronic communication. In response, academic researchers have attempted to explain consumer- and firm-related phenomena related to digital, social media, and mobile marketing (DSMM). This paper presents a critical historical analysis of, and forward-looking agenda for, this work. First, we assess marketing’s contribution to understanding DSMM since 2000. Extant research falls under three eras, and a fourth era currently underway. Era 1 focused on digital tools and platforms as consumer and marketer decision aids. Era 2 studied online communications channels (e.g., online forums) as word of mouth marketing “laboratories,” capturing the potential of DSMM for social information transmission. Era 3 embraced the notion of “connected consumers” by considering various antecedents and consequences of socially interconnected consumers in marketplaces. Era 4, currently starting, considers mobile marketing and brings psychological and social theories to bear on emergent DSMM issues. Second, we critique the DSMM literature and advance a series of recommendations for future research. While we find much to applaud, we argue that several problems limit the relevance of this research moving forward and suggest ways to alleviate these concerns moving forward

    Definition and Demonstration of a Methodology for Validating Aircraft Trajectory Predictors

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    This paper presents a new methodology for validating an aircraft trajectory predictor, inspired by the lessons learned from a number of field trials, flight tests and simulation experiments for the development of trajectory-predictor-based automation. The methodology introduces new techniques and a new multi-staged approach to reduce the effort in identifying and resolving validation failures, avoiding the potentially large costs associated with failures during a single-stage, pass/fail approach. As a case study, the validation effort performed by the Federal Aviation Administration for its En Route Automation Modernization (ERAM) system is analyzed to illustrate the real-world applicability of this methodology. During this validation effort, ERAM initially failed to achieve six of its eight requirements associated with trajectory prediction and conflict probe. The ERAM validation issues have since been addressed, but to illustrate how the methodology could have benefited the FAA effort, additional techniques are presented that could have been used to resolve some of these issues. Using data from the ERAM validation effort, it is demonstrated that these new techniques could have identified trajectory prediction error sources that contributed to several of the unmet ERAM requirements

    Preliminary evaluation of spectral, normal and meteorological crop stage estimation approaches

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    Several of the projects in the AgRISTARS program require crop phenology information, including classification, acreage and yield estimation, and detection of episodal events. This study evaluates several crop calendar estimation techniques for their potential use in the program. The techniques, although generic in approach, were developed and tested on spring wheat data collected in 1978. There are three basic approaches to crop stage estimation: historical averages for an area (normal crop calendars), agrometeorological modeling of known crop-weather relationships agrometeorological (agromet) crop calendars, and interpretation of spectral signatures (spectral crop calendars). In all, 10 combinations of planting and biostage estimation models were evaluated. Dates of stage occurrence are estimated with biases between -4 and +4 days while root mean square errors range from 10 to 15 days. Results are inconclusive as to the superiority of any of the models and further evaluation of the models with the 1979 data set is recommended

    Hypertrophic cardiomyopathy in a large community-based population: clinical outcome and identification of risk factors for sudden cardiac death and clinical deterioration

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    AbstractObjectivesThis study evaluates the clinical course and identifies risk factors for sudden cardiac death (SCD) and clinical deterioration in hypertrophic cardiomyopathy (HCM) in a large community-based population. Comparison was made with data from six tertiary referral and six nonreferral institutions.BackgroundHypertrophic cardiomyopathy is a disease with marked heterogeneity in clinical presentation and prognosis. Risk factors for SCD are not well defined in patients free of referral bias.MethodsBetween 1970 and 1999, 225 consecutive patients (mean age [±SD] 41±16 years) were examined and followed at yearly intervals.ResultsForty-four deaths were recorded of which 27 cases were cardiovascular. Fourteen patients died suddenly, six were successfully resuscitated, and seven patients died of congestive heart failure. The annual mortality, annual cardiac mortality, and annual mortality due to sudden death were 1.3%, 0.8%, and 0.6%, respectively. At least one New York Heart Association (NYHA) functional class deterioration was reported in 33% of the patients with a significant (≥50 mm Hg) left ventricular outflow tract (LVOT) gradient in contrast to 7% without obstruction. The presence of syncope was related to SCD (p < 0.05). Younger age and more severe functional limitation distinguishes patients from in hospital-based centers from the ones in community-based centers.ConclusionsHypertrophic cardiomyopathy is a benign disease in an unselected population with a low incidence of cardiac death. Syncope was associated with a higher incidence of SCD and patients with a significant LVOT obstruction were more susceptible to clinical deterioration

    Effect of pH of amine fluoride containing toothpastes on enamel remineralization in vitro

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    <p>Abstract</p> <p>Background</p> <p>One of the important factors of the demineralization and remineralization equilibrium of enamel is the pH of the surrounding solutions. Effort has been laid in the formulation of different fluoride compounds and the fluoride content in toothpastes but much less is known about the influence of the pH of the toothpastes on their effectiveness. It was therefore the aim of this study to investigate the influence of different pH levels on enamel remineralization in an in vitro experiment using polarization light microscopy and EDX quantitative element analysis.</p> <p>Methods</p> <p>A 5 Ă— 5 mm window on the enamel surface of 40 caries free extracted human premolars was demineralized in a hydroxyethylcellulose solution at pH 4.8. The teeth were divided into 8 groups and the lower half of the window was covered with varnish serving as control. Each group was then immersed in toothpaste slurry containing amine fluoride (1400 ppm) at pH 4.1, 4.5, 5.1 and 6.9 or control toothpaste slurry without fluoride at pH 4.3, 4.7, 5.3 and 7.0. Serial sections were cut through the lesions and investigated with polarization light microscopy and quantitative EDX element analysis.</p> <p>Results</p> <p>The PLM results showed a decreased porous volume of the body of the lesion after incubation with fluoridated toothpaste at pH 4.53 and 5.16. No differences between the experimental window and the control window were found in the other groups. The quantitative element analysis showed no differences in the element content of any of the groups.</p> <p>Conclusion</p> <p>From the results it can be concluded that slightly acidified fluoridated dentifrices may have a certain positive effect on enamel remineralization.</p

    On the Hybrid Extension of CTL and CTL+

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    The paper studies the expressivity, relative succinctness and complexity of satisfiability for hybrid extensions of the branching-time logics CTL and CTL+ by variables. Previous complexity results show that only fragments with one variable do have elementary complexity. It is shown that H1CTL+ and H1CTL, the hybrid extensions with one variable of CTL+ and CTL, respectively, are expressively equivalent but H1CTL+ is exponentially more succinct than H1CTL. On the other hand, HCTL+, the hybrid extension of CTL with arbitrarily many variables does not capture CTL*, as it even cannot express the simple CTL* property EGFp. The satisfiability problem for H1CTL+ is complete for triply exponential time, this remains true for quite weak fragments and quite strong extensions of the logic

    The effects of fruit smoothies on enamel erosion

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    Objectives: This prospective, randomised in vitro study was to investigate the pH and titratable acidity of fruit smoothie drinks and to assess the effect of these drinks on enamel erosion. Method: Fifty enamel slabs were divided into five groups which were allocated to the sample solutions groups: Innocent® smoothie strawberries and bananas (SB), Innocent® smoothie mangoes and passion fruit (MP) and Diet Coke. Distilled deionised water (DD) was used as negative control and citric acid 0.3 % as positive control. All the slabs were subjected to a 21-day pH cycling regime involving 2 min of immersions, five times a day with appropriate remineralization periods in between. Measurement of surface loss was assessed using profilometry. Independent sample t tests were used to compare mean. Results: The titratable acidity for both test smoothies were 3.5-4 times more than that needed to neutralise Diet Coke and citric acid 0.3 %. The pH of SB, MP smoothie and Diet Coke was found to be 3.73, 3.59 and 2.95, respectively. MP smoothie caused the greatest amount of surface loss followed by Diet Coke. Both smoothies were found to cause significant surface loss. MP smoothie resulted in significantly higher surface loss compared with MB smoothie and citric acid 3 %. Conclusion: The smoothies tested were acidic and had high titratable acidity. They produced a significant erosion of enamel in vitro. The results of this study suggest that there should be increased awareness of the erosive effects of smoothies especially as their consumption seems to be on the increase

    Extreme interatrial conduction delay and regularization of atrial arrhythmias in a subgroup of patients with hypertrophic cardiomyopathy

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    Background: Hypertrophic cardiomyopathy (HCM) patients may develop interatrial activation delay, indicated by a complete separation of the right and left atrial activation on the ECG. This study aimed to determine the prevalence of interatrial activation delay and the relation to atrial tachycardia (AT) cycle length (CL) in HCM patients. Methods: 159 HCM patients were included (mean age 52±14y). In group I (n=15, 9%) patients had atrial arrhythmias and progressive ATCL. In group II (n=22, 14%) patients had a stable ATCL. In group III (n=122, 77%) HCM patients without AT were included. P wave morphology and change in P wave duration (δP and Pmax) and changes in ATCL (δATCL) were analyzed. Mean follow-up was 8.7±4.7years. Results: In group I 33% (n=5) had separated P waves. In group II no P wave separation was identified (OR 1.50 [1.05-2.15], p=0.007). In group I patients were older compared to group III (62.6±15.1 vs. 50.2±14.0y, p=0.002) and had longer follow-up (13.4±2.2 vs. 7.8±4.6y, p<0.001). In group III Pmax and δP were significantly lower (105.1±22.0ms and 8.9±13.2ms, both p<0.0001). Group I patients had an increased LA size compared to group II (61.1±11.6 vs. 53.7±7.5mm, p=0.028) and higher E/A and E/E prime ratios (p=0.007; p=0.037, respectively). In group I 93.3% of the identified mutations were typical Dutch founder mutations of the MYBPC3 gene. Conclusion: In HCM patients a unique combination of separated P waves and regularization of ATs is associated with larger atria, higher LA pressures and myosin binding protein mutations

    Beneficial effects of conversion from cyclosporine to azathioprine on fibrinolysis in renal transplant recipients

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    Cyclosporin A (CsA) has been implicated as one of the factors contributing to the high cardiovascular morbidity and mortality after renal transplantation. This may be mediated by either a high prevalence of conventional risk factors for atherosclerosis, such as hypertension, hypercholesterolemia, and diabetes mellitus, or by impairment of the fibrinolytic activity evoked by CsA, possibly through interference with prostanoid metabolism. We therefore assessed the impact of conversion of CsA to azathioprine immunosuppressive treatment on parameters of fibrinolytic activity and plasma concentration of the prostanoids prostaglandin E2 and thromboxane B2 in 18 stable renal transplant recipients. During CsA, mean arterial pressure and serum creatinine were significantly higher than during azathioprine (116+/-15 mm Hg versus 106+/-13 mm Hg, P=0.0003; and 147+/-34 micromol/L versus 127+/-35 micromol/L, P=0.002; mean+/-SD). On conversion, the plasma tissue plasminogen activator activity increased from 1.2 (1.1 to 1.7; median, 95% CI) to 1.8 (1.6 to 2.0) IU/mL (P=0.011), without a significant change of the plasminogen activator antigen concentration. This was associated with a substantial decrease in plasminogen activator inhibitor-1 activity from 10.4 (8.5 to 16.7) to 6.4 (5.6 to 9.2) IU/mL (P=0.009). Furthermore, plasma levels of prostaglandin E2 and thromboxane B2 markedly decreased (from 9.7 [7.4 to 12.9] to 4.6 [4.3 to 8.1] pg/mL, P=0.0006; and from 106.1 [91.7 to 214.2] to 70.2 [50.3 to 85.6] pg/mL, P=0.002, respectively). During CsA, but not azathioprine, plasma tissue plasminogen activator antigen and plasminogen activator inhibitor-1 levels correlated significantly with prostaglandin E2 (r=0.53, P=0.02; and r=0.60, P=0.008, respectively), and thromboxane B2 (r=0.75, P=0.0001; and r=0.77, P=0.0001, respectively) levels. In conclusion, CsA induced substantial impairment of fibrinolytic activity, which recovered after conversion to azathioprine. The impaired fibrinolysis observed during CsA treatment may be caused by modulation of eicosanoid production or metabolism in vascular endothelial cells and possibly contributes to the high incidence of cardiovascular disease after kidney transplantation

    The Normal College News, October 28, 1909

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    Objective Currently, consensus is lacking on the relation between closure of atrial septal defect (ASD) and the incidence of atrial fibrillation (AF), which is a known complication in ASD patients. More importantly, studies reporting on the treatment applied for AF in ASD patients are scarce. The aims of this study were (1) to assess the incidence of AF in ASD patients, (2) to study the relation between closure and AF and (3) to evaluate applied treatment strategies. Methods A single-centre retrospective study in 173 patients with an ASD was performed. We analysed the incidence of AF, the relation of AF with closure, method of closure and the treatment success of therapies applied. Results Almost 20% of patients with an ASD developed AF, with a mean age of 59 (±14) years at first presentation of AF during a median clinical follow-up of 43 (29-59) years. Older age (OR 1.072; p<0.001) and a dilated left atrium (OR 3.727; p=0.009) were independently associated with new-onset AF. Closure itself was not independently associated with AF. First applied treatment strategy was rhythm control in 77%. Of the 18 patients treated with antiarrhythmic drugs 50% had at least 1 recurrence of AF. Conclusion No clear relation between closure of the ASD and AF could be assessed. This is the first study describing applied therapy for AF in ASD patients of which medical rhythm control was the most applied strategy with a disappointing efficacy
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