ALBERT

Description: This collection focuses primarily on Peirce’s realism, pragmatism, and theism, with attention to his tychism and synechism.

Description: In recent years, Charles Sanders Peirce has emerged, in the eyes of philosophers both in America and abroad, as one of America’s major philosophical thinkers. His work has forced us back to philosophical reflection about those basic issues that inevitably confront us as human beings, especially in an age of science. Peirce’s concern for experience, for what is actually encountered, means that his philosophy, even in its most technical aspects, forms a reflective commentary on actual life and on the world in which it is lived. In Charles S. Peirce: On Norms and Ideals, Potter argues that Peirce’s doctrine of the normative sciences is essential to his pragmatism. No part of Peirce’s philosophy is bolder than his attempt to establish esthetics, ethics, and logic as the three normative sciences and to argue for the priority of esthetics among the trio. Logic, Potter cites, is normative because it governs thought and aims at truth; ethics is normative because it analyzes the ends to which thought should be directed; esthetics is normative and fundamental because it considers what it means to be an end of something good in itself. This study shows that pierce took seriously the trinity of normative sciences and demonstrates that these categories apply both to the conduct of man and to the workings of the cosmos. Professor Potter combines sympathetic and informed exposition with straightforward criticism and he deals in a sensible manner with the gaps and inconsistencies in Peirce’s thought. His study shows that Peirce was above all a cosmological and ontological thinker, one who combined science both as a method and as result with a conception of reasonable actions to form a comprehensive theory of reality. Peirce’s pragmatism, although it has to do with "action and the achievement of results, is not a glorification of action but rather a theory of the dynamic nature of things in which the "ideal" dimension of reality – laws, nature of things, tendencies, and ends – has genuine power for directing the cosmic order, including man, toward reasonable goals.

Description: Unoccupied aerial vehicle laser scanning (UAV-LS) has been increasingly used for forest structure assessment in recent years due to the potential to directly estimate individual tree attributes and availability of commercial solutions. However, standardised procedures for campaign planning are still largely missing. This study investigated scanner properties and flight planning to provide recommendations on minimising forest canopy occlusion and thereby maximise exploration of canopy volume. A flight campaign involving two UAV-LS systems was conducted over a dense, wet tropical forest at the Paracou research station (French Guiana). Four experiments on scanner properties and flight planning were conducted, analysed and recommendations derived. First, the scanner pulse repetition rate (PRR) should be at least 100 kHz per 1 m s−1 flight speed based on 360° FOV for exploration of middle canopy strata (5 m to 20 m). Higher PRR are beneficial for exploration of lower canopy (5 m) but would need to be increased exponentially to achieve linear improvement. Alternatively, flight speed could be reduced within the constraints given by the inertial measurement unit (IMU), but would increase flight time. Second, the scanner maximum range was identified as a proxy for the laser pulse power, which positively impacts canopy exploration. This was particularly the case when using multi-return capabilities. No saturation could be observed when increasing the laser power, suggesting that this is currently a limiting factor. Additionally, a smaller laser beam divergence and pulse width were plausible reasons for better exploration of the upper canopy just below the top of canopy. Third, off-nadir scanning angles up to 20° were found to result in similar occlusions, suggesting a practical FOV of 40° in the investigated dense forest. This number might be larger for open canopies. UAV-LS systems with viewing geometries that focus laser pulses downwards and within optimal ranges should be preferred. Fourth, using different horizontal flight directions in the mission planning favours minimisation of occlusion. A minimum of two different flight directions is suggested. However, specific optimal yaw angles were not possible to predict before flight. Therefore, including multiple directions ensures coverage of all possible configurations. Many of these investigated features can be optimised independently from each other, and should be considered before acquisition of new UAV-LS systems and flight mission planning. These results support the establishment of general guidelines for the investment in UAV-LS systems and optimal mission planning for forest structure assessment.

Description: Leaf area is a key structural characteristic of forest canopies because of the role of leaves in controlling many biological and physical processes occurring at the biosphere-atmosphere transition. High pulse density Airborne Laser Scanning (ALS) holds promise to provide spatially resolved and accurate estimates of plant area density (PAD) in forested landscapes, a key step in understanding forest functioning: phenology, carbon uptake, transpiration, radiative balance etc. Inconsistencies between different ALS sensors is a barrier to generating globally harmonised PAD estimates. The basic assumption on which PAD estimation is based is that light attenuation is proportional to vegetation area density. This study shows that the recorded extinction strongly depends on target detectability which is influenced by laser characteristics (power, sensitivity, wavelength). Three different airborne laser scanners were flown over a wet tropical forest at the Paracou research station in French Guiana. Different sensors, flight heights and transmitted power levels were compared. Light attenuation was retrieved with an open source ray-tracing code (http://amapvox.org). Direct comparison revealed marked differences (up-to 25% difference in profile-averaged light attenuation rate and 50% difference at particular heights) that could only be explained by differences in scanner characteristics. We show how bias which may occur under various acquisition conditions can generally be mitigated by a sensor intercalibration. Alignment of light weight lidar attenuation profiles to ALS reference attenuation profiles is not always satisfactory and we discuss what are the likely sources of discrepancies. Neglecting the dependency of apparent light attenuation on scanner properties may lead to biases in estimated vegetation density commensurate to those affecting light attenuation estimates. Applying intercalibration procedures supports estimation of plant area density independent of acquisition characteristics.

Description: This article is distributed under the terms of the Creative Commons Public Domain. The definitive version was published in PLoS ONE 8 (2013): e55273, doi:10.1371/journal.pone.0055273.

Description: Georges Bank is a large, shallow feature separating the Gulf of Maine from the Atlantic Ocean. Previous studies demonstrated a strong tidal-mixing front during the warm season on the northern bank margin between thermally stratified water in the Gulf of Maine and mixed water on the bank. Tides transport warm water off the bank during flood tide and cool gulf water onto the bank during ebb tide. During 10 days in August 2009, we mapped frontal temperatures in five study areas along ~100 km of the bank margin. The seabed “frontal zone”, where temperature changed with frontal movment, experienced semidiurnal temperature maxima and minima. The tidal excursion of the frontal boundary between stratified and mixed water ranged 6 to 10 km. This “frontal boundary zone” was narrower than the frontal zone. Along transects perpendicular to the bank margin, seabed temperature change at individual sites ranged from 7.0°C in the frontal zone to 0.0°C in mixed bank water. At time series in frontal zone stations, changes during tidal cycles ranged from 1.2 to 6.1°C. The greatest rate of change (−2.48°C hr−1) occurred at mid-ebb. Geographic plots of seabed temperature change allowed the mapping of up to 8 subareas in each study area. The magnitude of temperature change in a subarea depended on its location in the frontal zone. Frontal movement had the greatest effect on seabed temperature in the 40 to 80 m depth interval. Subareas experiencing maximum temperature change in the frontal zone were not in the frontal boundary zone, but rather several km gulfward (off-bank) of the frontal boundary zone. These results provide a new ecological framework for examining the effect of tidally-driven temperature variability on the distribution, food resources, and reproductive success of benthic invertebrate and demersal fish species living in tidal front habitats.

Description: This study was supported by salary funds from the regular annual salary budget from Northeast Fisheries Science Center (NEFSC) and United States Geological Survey Woods Hole Coastal and Marine Science Center (USGS WH C&MSC), respectively; ship time funds from the NEFSC annual budget for days-at-sea ship operations; equipment from the NEFSC and USGS WH C&MSC annual equipment budgets.