1,252 research outputs found
Marcus Joseph Wright memoirs, MSS.1585
No full textAbstract: An incomplete typescript copy (18 pp.) of, "Memoirs of Brigadier General Marcus J. Wright, CSA."Scope and Content Note: The collection contains an incomplete typescript copy (18 pp.) of, "Memoirs of Brigadier General Marcus J. Wright, CSA," which includes a family genealogy, and accounts of his early life in Tennessee and his career.Biographical/Historical Note: Confederate General and author from Tennessee
Marcus on Belief and Belief in the Impossible
No full textI review but don’t endorse Marcus’ arguments that impossible beliefs are impossible. I defend her claim that belief’s objects are, in some important sense, not the bearers of truth and falsity, discuss her dispositionalism about belief, and argue it’s a good fit with the idea that belief’s objects are Russellian states of affairs.
Reviso, pero no suscribo, los argumentos de Marcus a favor de que las creencias imposibles son imposibles.
Defiendo su tesis de que los objetos de las creencias no son, en algún sentido importante, los soportes
de la verdad y la falsedad; discuto su disposicionalismo acerca de las creencias y argumento que encaja bien
con la idea de que los objetos de las creencias son estados de cosas russellianos
Data‐driven counterfactual evaluation of management outcomes to improve emergency conservation decisions
No full textMonitoring is needed to assess conservation success and improve management, but naïve or simplistic interpretation of monitoring data can lead to poor decisions. We illustrate how to counter this risk by combining decision-support tools and quantitative counterfactual analysis. We analyzed 20 years of egg rescue for tara iti (Sternula nereis davisae) in Aotearoa New Zealand. Survival is lower for rescued eggs; however, only eggs perceived as imminently threatened by predators or weather are rescued, so concluding that rescue is ineffective would be biased. Equally, simply assuming all rescued eggswould have died if left in situ is likely to be simplistic. Instead, we used the monitoring data itself to estimate statistical support for a wide space of uncertain counterfactuals about decisions and fate of rescued eggs. Results suggest under past management, rescuing and leaving eggs would have led to approximately the same overall fledging rate, because of likely imperfect threat assessment and low survival of rescued eggs to fledging. Managers are currently working to improve both parameters. Our approach avoids both naïve interpretation of observed outcomes and simplistic assumptions thatmanagement is always justified, using the same data to obtain unbiased quantitative estimates of counterfactual support
Statistical Development of Animal Density Estimation Using Random Encounter Modelling
No full textCamera trapping is widely used in ecological studies to estimate animal density, although these studies are largely restricted to animals that can be identified to the individual level. The random encounter model, developed by Rowcliffe et al. (J Anal Ecol 45(4):1228–1236, 2008), estimates animal density from camera-trap data without the need to identify animals. Although the REM can provide reliable density estimates, it lacks the potential to account for the multiple sources of variance in the modelling process. The density estimator in REM is a ratio, and since the variance of a ratio estimator is intractable, we examine and compare the finite sample performance of many approaches for obtaining confidence intervals via simulation studies. We also propose an integrated random encounter model as a parametric alternative, which is flexible and can incorporate covariates and random effects. A data example from Whipsnade Wild Animal Park, Bedfordshire, south England, is used to demonstrate the application of these methods
Economical crowdsourcing for camera trap image classification
No full textCamera trapping is widely used to monitor mammalian wildlife but creates large image datasets that must be classified. In response, there is a trend towards crowdsourcing image classification. For high‐profile studies of charismatic faunas, many classifications can be obtained per image, enabling consensus assessments of the image contents. For more local‐scale or less charismatic communities, however, demand may outstrip the supply of crowdsourced classifications. Here, we consider MammalWeb, a local‐scale project in North East England, which involves citizen scientists in both the capture and classification of sequences of camera trap images. We show that, for our global pool of image sequences, the probability of correct classification exceeds 99% with about nine concordant crowdsourced classifications per sequence. However, there is high variation among species. For highly recognizable species, species‐specific consensus algorithms could be even more efficient; for difficult to spot or easily confused taxa, expert classifications might be preferable. We show that two types of incorrect classifications – misidentification of species and overlooking the presence of animals – have different impacts on the confidence of consensus classifications, depending on the true species pictured. Our results have implications for data capture and classification in increasingly numerous, local‐scale citizen science projects. The species‐specific nature of our findings suggests that the performance of crowdsourcing projects is likely to be highly sensitive to the local fauna and context. The generality of consensus algorithms will, thus, be an important consideration for ecologists interested in harnessing the power of the crowd to assist with camera trapping studies
Food aquisition and predator avoidance in a Neotropical rodent
No full textForaging activity in animals reflects a compromise between acquiring food and avoiding predation. The Risk Allocation Hypothesis predicts that prey animals optimize this balance by concentrating their foraging activity at times of relatively low predation risk, as much as their energy status permits, but empirical evidence is scarce. We used a unique combination of automated telemetry, manual radio telemetry and camera trapping to test whether activity at high-risk times declined with food availability, as predicted, in a Neotropical forest rodent, the Central American agouti (Dasyprocta punctata). We found that the relative risk of predation by the main predator, the Ocelot (Leopardus pardalis), estimated as the ratio of ocelot to agouti activity on camera trap footage, was up to four orders of magnitude higher between sunset and sunrise than during the rest of the day. Kills of radio-tracked agoutis by ocelots during this high-risk period far exceeded expectations given agouti activity. Both telemetric monitoring of radio-tagged agoutis and camera monitoring of burrow entrances indicated that agoutis exited their burrows later at dawn, entered their burrows earlier at dusk, and had lower overall activity levels, as they lived in areas with higher food abundance. Thus, agoutis avoided activity during the high-risk period more strongly as access to food was higher. Our study provides quantitative empirical evidence of prey animals concentrating their activity at times of relatively low predation risk
Quantifying the sensitivity of camera traps:an adapted distance sampling approach
No full text1. Abundance estimation is a pervasive goal in ecology. The rate of detection by motion-sensitive camera traps can, in principle, provide information on the abundance of many species of terrestrial vertebrates that are otherwise difficult to survey. The random encounter model (REM, Rowcliffe et al. 2008) provides a means estimating abundance from camera trap rate but requires camera sensitivity to be quantified. 2. Here, we develop a method to estimate the area effectively monitored by cameras, which is one of the most important codeterminants of detection rate. Our method borrows from distance sampling theory, applying detection function models to data on the position (distance and angle relative to the camera) where the animals are first detected. Testing the reliability of this approach through simulation, we find that bias depends on the effective detection angle assumed but was generally low at less than 5% for realistic angles typical of camera traps. 3. We adapted standard detection functions to allow for the possibility of smaller animals passing beneath the field of view close to the camera, resulting in reduced detection probability within that zone. Using a further simulation to test this approach, we find that detection distance can be estimated with little or no bias if detection probability is certain for at least some distance from the camera. 4. Applying this method to a 1-year camera trapping data set from Barro Colorado Island, Panama, we show that effective detection distance is related strongly positively to species body mass and weakly negatively to species average speed of movement. There was also a strong seasonal effect, with shorter detection distance during the wet season. Effective detection angle is related more weakly to species body mass, and again strongly to season, with a wider angle in the wet season. 5. This method represents an important step towards practical application of the REM, including abundance estimation for relatively small
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Networking Past and Present
No full textA special feature in the Social Evolution Forum with R.I.M. Dunbar as the author of the focus article. Commentaries by Nicolas Baumard, Marcus J. Hamilton, Paul Hooper, Daniel N. Finkel, and Herbert Gintis
From concept to certification; interview with AD&C co-founder and CEO Marcus Basien
No full textBefore any aircraft concept takes to the sky, air travel authorities require the aircraft be certified. One would expect a big organisation like EASA would function like a centralised verification authority. However, small companies like Aircraft Design & Certification Ltd. offer certification services for general aviation aircraft. Leonardo Times sat down with AD&C co-founder Marcus Basien to discuss the process of certification, future developments of the industry and possibilities for Aerospace Engineering students.Aerospace Engineerin
Chemical characteristics of Delaware River water, Trenton, N.J., to Marcus Hook, PA.
No full textThis progress report gives the results of an investigation of the quality of water in the Delaware River from Trenton, N. J. to Marcus Hook, Pa., for the period August 1949 to December 1952. The Delaware River is the principal source of water for the many industries and municipal water supplies along this reach of the river and both industries and municipalities use it for the disposal of their wastes. Consequently, a study of the quality of the water and variations in the quality caused by changes in streamflow, tidal effects, pollution and other factors is important to the many users. In both New Jersey and Pennsylvania steps are being taken to abate pollution, thus it is of more than passing interest to measure the effects of waste treatment on the quality of the Delaware River water.
At average or higher rates of streamflow the mineral content of the water increases slightly from Trenton to Marcus Hook. There is little variation in the concentration of dissolved minerals from bank to bank or from top to bottom of the river. At times of protracted low rates of flow the effect of ocean water mixing with the river water may be noted as far upstream as Philadelphia. At such times the salinity is often greater near the bottom of the river than near the top. The increase in chloride concentration upstream from Philadelphia is small compared to the rapid increase downstream from Philadelphia. Temperatures of offshore water vary with the season, but on a given day are substantially uniform throughout the reach of the river from Trenton to Marcus Hook.
The water contains less dissolved oxygen as it flows downstream indicating that oxygen is being consumed by oxidizable matter. From Philadelphia downstream there are periods, especially in late summer, when the dissolved oxygen is barely sufficient to meet the oxygen demands of the pollution load.Geological Survey Water-Supply Paper 126
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