Threshold Regression for Survival Analysis: Modeling Event Times by a Stochastic Process Reaching a Boundary

Many researchers have investigated first hitting times as models for survival data. First hitting times arise naturally in many types of stochastic processes, ranging from Wiener processes to Markov chains. In a survival context, the state of the underlying process represents the strength of an item or the health of an individual. The item fails or the individual experiences a clinical endpoint when the process reaches an adverse threshold state for the first time. The time scale can be calendar time or some other operational measure of degradation or disease progression. In many applications, the process is latent (i.e., unobservable). Threshold regression refers to first-hitting-time models with regression structures that accommodate covariate data. The parameters of the process, threshold state and time scale may depend on the covariates. This paper reviews aspects of this topic and discusses fruitful avenues for future research.Comment: Published at http://dx.doi.org/10.1214/088342306000000330 in the Statistical Science (http://www.imstat.org/sts/) by the Institute of Mathematical Statistics (http://www.imstat.org

The Zika Virus Threat: How Concerns About Scientists May Undermine Efforts to Combat the Pandemic

Using data from the University of New Hampshire’s October 2016 Granite State Poll, authors Thomas Safford, Lawrence Hamilton, and Emily Whitmore investigate how New Hampshire residents view the Zika crisis. They report that most New Hampshire residents believe Zika is only a minor threat to public health in the United States, and they generally trust the CDC as a source of information about the virus. The data also show that, while there is doubt about the government’s ability to control the spread of the virus, the public feels that emergency federal funding to combat Zika should be a priority. They discuss that many Granite Staters have real concerns about the practice of science, believing scientists change their findings to get the answers they want. More importantly, individuals who questioned the integrity of scientists are less likely to believe Zika is a threat, have confidence in the government’s ability to combat the virus, trust the CDC, and to prioritize emergency funding. They conclude that these results suggest that health officials working to engage the public in efforts to control the spread of Zika must not only discuss risks associated with the virus and mechanisms of transmission, but also confront science skepticism and potential concerns about the integrity of the scientists gathering data related to Zika and other infectious diseases

Detection of Hemlock Woolly Adelgid (Hemiptera: Adelgidae) Infestations with Sticky Traps

We deployed sticky traps underneath the crown of eastern hemlock, Tsuga canadensis (L.) Carrière, to assess their sensitivity at detecting crawlers (1st instar nymphs) of the non-native hemlock woolly adelgid, Adelges tsugae Annand (Hemiptera: Adelgidae). We found these traps more sensitive at detecting infested trees with low densities of A. tsugae than branch-tip sampling with pole pruners. We observed two peaks of crawler abundance at all sites: these peaks likely represented the timing of the progrediens and sistens crawler stages of A. tsugae. Deployment of sticky traps in treated and high-risk stands may prove useful at detecting residual and new infestations, respectively

Remote sensing program activity report

Major accomplishments in an effort to encourage investigation and technology transfer for practical applications of remote sensing to solve Earth resources problems in Vermont include: (1) acquisition, installation, and operation of the ORSER digital processing system on the University's IBM 3031 computer; (2) acquisition and operation of printing and CRT computer terminals for remote access to computer facilities for analysis of remotely sensed digital tape; (3) acquisition and operation of optical interpretation and image transfer devices for use with all types of aerial photography; (4) development of audio visual and other training materials for use in presentations, workshops, and short courses to enhance technology transfer; and (5) cooperation government agencies in demonstration projects to show the feasibility of using remote sensing technology

Photic effects on sustained performance

Research is described which evaluates manipulating environmental light intensity as a means to attenuate fatigue. A counter balanced, within-subjects design was used to compare nine male subjects exposed to dim (100 lux) and bright (3000 lux) light conditions. Oral temperature values were greater for the bright light group over the dim light condition. Melatonin levels were suppressed by bright light treatment. Also, the frequency of eye blink rate was less for subjects during bright over dim light exposure. Light exposure was without effect on subjective fatigue. However, irrespective of light condition, significant effects on confusion, fatigue, and vigor mood dimensions were found as a result of 30 hour sleep deprivation. The findings suggest that bright lights may be used to help sustain nocturnal activity otherwise susceptible to fatigue. Such findings may have implications for the lighting arrangements on space flights during the subjective night for astronauts

Is it possible to increase the sustainability of arable and ruminant agriculture by reducing inputs?

Until recently, agricultural production was optimised almost exclusively for profit but now farming is under pressure to meet environmental targets. A method is presented and applied for optimising the sustainability of agricultural production systems in terms of both economics and the environment. Components of the agricultural production chain are analysed using environmental life-cycle assessment (LCA) and a financial value attributed to the resources consumed and burden imposed on the environment by agriculture, as well as to the products. The sum of the outputs is weighed against the inputs and the system considered sustainable if the value of the outputs exceeds those of the inputs. If this ratio is plotted against the sum of inputs for all levels of input, a diminishing returns curve should result and the optimum level of sustainability is located at the maximum of the curve. Data were taken from standard economic almanacs and from published LCA reports on the extent of consumption and environmental burdens resulting from farming in the UK. Land-use is valued using the concept of ecosystem services. Our analysis suggests that agricultural systems are sustainable at rates of production close to current levels practiced in the UK. Extensification of farming, which is thought to favour non-food ecosystem services, requires more land to produce the same amount of food. The loss of ecosystem services hitherto provided by natural land brought into production is greater than that which can be provided by land now under extensive farming. This loss of ecosystem service is large in comparison to the benefit of a reduction in emission of nutrients and pesticides. However, food production is essential, so the coupling of subsidies that represent a relatively large component of the economic output in EU farming, with measures to reduce pollution are well-aimed. Measures to ensure that as little extra land is brought into production as possible or that marginal land is allowed to revert to nature would seem to be equally well-aimed, even if this required more intensive use of productive areas. We conclude that current arable farming in the EU is sustainable with either realistic prices for products or some degree of subsidy and that productivity per unit area of land and greenhouse gas emission (subsuming primary energy consumption) are the most important pressures on the sustainability of farming

Exploring the Usefulness of the Dispositional Flow Scale for Outdoor Recreation Activities

The Dispositional Flow Scale (DFS), developed by Jackson et al. (1998), measures an individual’s dispositional tendency to experience flow, a psychological state of optimal experience originally conceptualized by Csikszentmihalyi in 1975. The DFS, developed in the realm of sports psychology, has primarily been used with participants of urban sports settings, such as: football, running, or tennis. This study explores the validity and reliability of applying the DFS to outdoor recreation activities. A stratified sample of 406 visitors to the Bob Marshall Wilderness Complex in Montana was contacted during the summer of 2004. A survey response rate of 74 percent was achieved with on-site contact, mail back questionnaires, follow-up reminder postcards, and replacement mailing. The primary activities reported were hiking, horseback riding, and fishing. Results from confirmatory factor analysis, a special application of structural equation modeling, confirm that the DFS displays a satisfactory level of validity and reliability when applied to these activities