2,482 research outputs found

    Non-Disruptive Tactics of Suppression Are Superior in Countering Terrorism, Insurgency, and Financial Panics

    Get PDF
    BACKGROUND: Suppressing damaging aggregate behaviors such as insurgency, terrorism, and financial panics are important tasks of the state. Each outcome of these aggregate behaviors is an emergent property of a system in which each individual's action depends on a subset of others' actions, given by each individual's network of interactions. Yet there are few explicit comparisons of strategies for suppression, and none that fully incorporate the interdependence of individual behavior. METHODS AND FINDINGS: Here I show that suppression tactics that do not require the removal of individuals from networks of interactions are nearly always more effective than those that do. I find using simulation analysis of a general model of interdependent behavior that the degree to which such less disruptive suppression tactics are superior to more disruptive ones increases in the propensity of individuals to engage in the behavior in question. CONCLUSIONS: Thus, hearts-and-minds approaches are generally more effective than force in counterterrorism and counterinsurgency, and partial insurance is usually a better tactic than gag rules in quelling financial panics. Differences between suppression tactics are greater when individual incentives to support terrorist or insurgent groups, or susceptibilities to financial panic, are higher. These conclusions have utility for policy-makers seeking to end bloody conflicts and prevent financial panics. As the model also applies to mass protest, its conclusions provide insight as well into the likely effects of different suppression strategies undertaken by authoritarian regimes seeking to hold on to power in the face of mass movements seeking to end them

    Obesity is not associated with disease-free interval, melanoma-specific survival, or overall survival in patients with clinical stage IB-II melanoma after SLNB

    Get PDF
    BACKGROUND AND OBJECTIVES: Clinicopathologic characteristics have prognostic value in clinical stage IB‐II patients with melanoma. Little is known about the prognostic value of obesity that has been associated with an increased risk for several cancer types and worsened prognosis after diagnosis. This study aims to examine effects of obesity on outcome in patients with clinical stage IB‐II melanoma. METHODS: Prospectively recorded data of patients with clinical stage IB‐II melanoma who underwent sentinel lymph node biopsy (SLNB) between 1995 and 2018 at the University Medical Center of Groningen were collected from medical files and retrospectively analyzed. Cox‐regression analyses were used to determine associations between obesity (body mass index> 30), tumor (location, histology, Breslow‐thickness, ulceration, mitotic rate, SLN‐status) and patient‐related variables (gender, age, and social‐economic‐status [SES]) and disease‐free interval (DFI), melanoma‐specific survival (MSS), and overall survival (OS). RESULTS: Of the 715 patients, 355 (49.7%) were women, median age was 55 (range 18.6‐89) years, 149 (20.8%) were obese. Obesity did not significantly affect DFI (adjusted hazard ratio [HR] = 1.40; 95% confidence interval [CI] = 0.98–2.00; p = 0.06), MSS (adjusted HR = 1.48;95%CI = 0.97–2.25; p = 0.07), and OS (adjusted HR = 1.25; 95% CI = 0.85–1.85; p = 0.25). Increased age, arm location, increased Breslow‐thickness, ulceration, increased mitotic rate, and positive SLN‐status were significantly associated with decreased DFI, MSS, and OS. Histology, sex, and SES were not associated. CONCLUSION: Obesity was not associated with DFI, MSS, or OS in patients with clinical stage IB‐II melanoma who underwent SLNB

    Strategically Equivalent Contests

    Get PDF
    Using a two-player Tullock-type contest, we show that intuitively and structurally different contests can be strategically equivalent. Strategically equivalent contests generate the same best response functions and, as a result, the same equilibrium efforts. However, strategically equivalent contests may yield different equilibrium payoffs. We propose a simple two-step procedure to identify strategically equivalent contests. Using this procedure, we identify contests that are strategically equivalent to the original Tullock contest, and provide new examples of strategically equivalent contests. Finally, we discuss possible contest design applications and avenues for future theoretical and empirical research

    Prediction of photoperiodic regulators from quantitative gene circuit models

    Get PDF
    Photoperiod sensors allow physiological adaptation to the changing seasons. The external coincidence hypothesis postulates that a light-responsive regulator is modulated by a circadian rhythm. Sufficient data are available to test this quantitatively in plants, though not yet in animals. In Arabidopsis, the clock-regulated genes CONSTANS (CO) and FLAVIN, KELCH, F-BOX (FKF1) and their lightsensitive proteins are thought to form an external coincidence sensor. We use 40 timeseries of molecular data to model the integration of light and timing information by CO, its target gene FLOWERING LOCUS T (FT), and the circadian clock. Among other predictions, the models show that FKF1 activates FT. We demonstrate experimentally that this effect is independent of the known activation of CO by FKF1, thus we locate a major, novel controller of photoperiodism. External coincidence is part of a complex photoperiod sensor: modelling makes this complexity explicit and may thus contribute to crop improvement

    Ovarian Control of Nectar Collection in the Honey Bee (Apis mellifera)

    Get PDF
    Honey bees are a model system for the study of division of labor. Worker bees demonstrate a foraging division of labor (DOL) by biasing collection towards carbohydrates (nectar) or protein (pollen). The Reproductive ground-plan hypothesis of Amdam et al. proposes that foraging DOL is regulated by the networks that controlled foraging behavior during the reproductive life cycle of honey bee ancestors. Here we test a proposed mechanism through which the ovary of the facultatively sterile worker impacts foraging bias. The proposed mechanism suggests that the ovary has a regulatory effect on sucrose sensitivity, and sucrose sensitivity impacts nectar loading. We tested this mechanism by measuring worker ovary size (ovariole number), sucrose sensitivity, and sucrose solution load size collected from a rate-controlled artificial feeder. We found a significant interaction between ovariole number and sucrose sensitivity on sucrose solution load size when using low concentration nectar. This supports our proposed mechanism. As nectar and pollen loading are not independent, a mechanism impacting nectar load size would also impact pollen load size

    Power Law versus Exponential State Transition Dynamics: Application to Sleep-Wake Architecture

    Get PDF
    BACKGROUND: Despite the common experience that interrupted sleep has a negative impact on waking function, the features of human sleep-wake architecture that best distinguish sleep continuity versus fragmentation remain elusive. In this regard, there is growing interest in characterizing sleep architecture using models of the temporal dynamics of sleep-wake stage transitions. In humans and other mammals, the state transitions defining sleep and wake bout durations have been described with exponential and power law models, respectively. However, sleep-wake stage distributions are often complex, and distinguishing between exponential and power law processes is not always straightforward. Although mono-exponential distributions are distinct from power law distributions, multi-exponential distributions may in fact resemble power laws by appearing linear on a log-log plot. METHODOLOGY/PRINCIPAL FINDINGS: To characterize the parameters that may allow these distributions to mimic one another, we systematically fitted multi-exponential-generated distributions with a power law model, and power law-generated distributions with multi-exponential models. We used the Kolmogorov-Smirnov method to investigate goodness of fit for the "incorrect" model over a range of parameters. The "zone of mimicry" of parameters that increased the risk of mistakenly accepting power law fitting resembled empiric time constants obtained in human sleep and wake bout distributions. CONCLUSIONS/SIGNIFICANCE: Recognizing this uncertainty in model distinction impacts interpretation of transition dynamics (self-organizing versus probabilistic), and the generation of predictive models for clinical classification of normal and pathological sleep architecture

    Has education lost sight of children?

    Get PDF
    The reflections presented in this chapter are informed by clinical and personal experiences of school education in the UK. There are many challenges for children and young people in the modern education system and for the professionals who support them. In the UK, there are significant gaps between the highly selective education provided to those who pay privately for it and to the majority of those educated in the state-funded system. Though literacy rates have improved around the world, many children, particularly boys, do not finish their education for reasons such as boredom, behavioural difficulties or because education does not ‘pay’. Violence, bullying, and sexual harassment are issues faced by many children in schools and there are disturbing trends of excluding children who present with behavioural problems at school whose origins are not explored. Excluded children are then educated with other children who may also have multiple problems which often just make the situation worse. The experience of clinicians suggests that school-related mental health problems are increasing in severity. Are mental health services dealing with the consequences of an education system that is not meeting children’s needs? An education system that is testing- and performance-based may not be serving many children well if it is driving important decisions about them at increasingly younger ages. Labelling of children and setting them on educational career paths can occur well before they reach secondary schools, limiting potential very early on in their developmental trajectory. Furthermore, the emphasis at school on testing may come at the expense of creativity and other forms of intelligence, which are also valuable and important. Meanwhile the employment marketplace requires people with widely different skills, with an emphasis on innovation, creativity, and problem solving. Is education losing sight of the children it is educating

    Relevance of large litter bag burial for the study of leaf breakdown in the hyporheic zone

    Get PDF
    Particulate organic matter is the major source of energy for most low-order streams, but a large part of this litter is buried within bed sediment during floods and thus become poorly available for benthic food webs. The fate of this buried litter is little studied. In most cases, measures of breakdown rates consist of burying a known mass of litter within the stream sediment and following its breakdown over time. We tested this method using large litter bags (15 x 15 cm) and two field experiments. First, we used litter large bags filled with Alnus glutinosa leaves (buried at 20 cm depth with a shovel) in six stations within different land-use contexts and with different sediment grain sizes. Breakdown rates were surprisingly high (0.0011–0.0188 day-1) and neither correlate with most of the physico-chemical characteristics measured in the interstitial habitats nor with the land-use around the stream. In contrast, the rates were negatively correlated with a decrease in oxygen concentrations between surface and buried bags and positively correlated with both the percentage of coarse particles (20–40 mm) in the sediment and benthic macro-invertebrate richness. These results suggest that the vertical exchanges with surface water in the hyporheic zone play a crucial role in litter breakdown. Second, an experimental modification of local sediment (removing fine particles with a shovel to increase vertical exchanges) highlighted the influence of grain size on water and oxygen exchanges, but had no effect on hyporheic breakdown rates. Burying large litter bags within sediments may thus not be a relevant method, especially in clogged conditions, due to changes induced through the burial process in the vertical connectivity between surface and interstitial habitats that modify organic matter processing

    Empirical estimates of prostate cancer overdiagnosis by age and prostate-specific antigen

    Get PDF
    Background: Prostate cancer screening depends on a careful balance of benefits, in terms of reduced prostate cancer mortality, and harms, in terms of overdiagnosis and overtreatment. We aimed to estimate the effect on overdiagnosis of restricting prostate specific antigen (PSA) testing by age and baseline PSA.Methods: Estimates of the effects of age on overdiagnosis were based on population based incidence data from the US Surveillance, Epidemiology and End Results database. To investigate the relationship between PSA and overdiagnosis, we used two separate cohorts subject to PSA testing in clinical trials (n = 1,577 and n = 1,197) and a population-based cohort of Swedish men not subject to PSA-screening followed for 25 years (n = 1,162).Results: If PSA testing had been restricted to younger men, the number of excess cases associated with the introduction of PSA in the US would have been reduced by 85%, 68% and 42% for age cut-offs of 60, 65 and 70, respectively. The risk that a man with screen-detected cancer at age 60 would not subsequently lead to prostate cancer morbidity or mortality decreased exponentially as PSA approached conventional biopsy thresholds. For PSAs below 1 ng/ml, the risk of a positive biopsy is 65 (95% CI 18.2, 72.9) times greater than subsequent prostate cancer mortality.Conclusions: Prostate cancer overdiagnosis has a strong relationship to age and PSA level. Restricting screening in men over 60 to those with PSA above median (>1 ng/ml) and screening men over 70 only in selected circumstances would importantly reduce overdiagnosis and change the ratio of benefits to harms of PSA-screening
    corecore