Trail Length Research Articles

Maximum Cardinality f -Matching in Time O ( n 2/3 m )

We present an algorithm that finds a maximum cardinality \(f\) -matching of a simple graph in time \(O(n^{2/3}m)\) . Here, \(f:V\to\mathbb{N}\) is a given function and an \(f\) -matching is a subgraph wherein each vertex \(v\in V\) has degree \(\leq f(v)\) . This result generalizes a string of algorithms that concentrate on simple bipartite graphs. The bipartite case is based on the notion of level graph, introduced by Dinic for network flow. In general graphs this notion breaks down: Vertices no longer have unique levels, and there are too many levels to analyze the corresponding level graph like bipartite graphs ( \(\Theta(n^{2})\) vs. \(n\) ). We use “natural” levels to prove properties of shortest augmenting trails (e.g., formulas for trail length). We use “shortened” levels to derive the algorithm’s time bound. The algorithm, unmodified, is also efficient on multigraphs, achieving time \(O(\min\{\sqrt{f(V)},n\} m)\) for \(f(V)=\sum_{v}f(v)\) . The special case \(f\equiv 1\) shows the algorithm duplicates the classic time bound for maximum cardinality matching, \(O(\sqrt{n} m)\) .

A robust iterative learning control for linear system with variable initial state and trail length

AbstractTo address the variable initial state and trail length this paper first presents a robust PD‐type open‐closed‐loop iterative learning control (ILC) law for a multiple‐input‐multiple‐output (MIMO) linear discrete‐time system. It is demonstrated that the convergence condition is dependent on the PD‐type feed‐forward learning gains, while an appropriate feedback learning gain can improve the ILC convergence performance. As a special case of PD‐type open‐closed‐loop ILC law, P‐type and D‐type open‐closed‐loop ILC laws are deduced. The three developed ILC laws ensure that as the number of iterations approaches infinity, the expectation of ILC tracking error will be constrained within a limited range, where the boundary is proportional to the initial state variation. Through a numerical simulation, the effectiveness of the proposed ILC laws is illustrated.

Managing abandoned Mediterranean mountain landscapes: The effects of donkey grazing on biomass control and floral diversity in pastures

Traditional Mediterranean Mountain landscapes in Spain have suffered dramatic environmental and social changes over the last seven decades. The loss of these landscapes has had consequences for biodiversity, soil erosion, landscape quality and ecosystem services as croplands and pastures were mainly converted into forests and scrublands. Many animal breeds present in traditional land uses such as the Catalan donkey (Equus asinus var. catalana), are also at risk of extinction, but can provide environmental services while recovering traditional landscapes. In Puy de Cinca, a village in mountainous northeast Spain, we studied how grazing by Catalan donkeys reduces pasture biomass and the effects on plant diversity in pastures. We used Sentinel-2 satellite imagery to calculate the Normalized Difference Vegetation Index (NDVI), a biomass sensitive spectral index, throughout the grazing period to monitor pasture biomass and compared it to pastures without grazing. We also calculated several plant diversity indicators in pastures with and without grazing donkeys. Furthermore, we studied land use changes over the last seven decades using old (1956) and current (2018) aerial images, with forest, agricultural lands, and trails interconnecting the village being mapped to understand landscape changes. The results indicated a great increase in the forested area (348.3 ± 17.0 ha). Meanwhile, a severe decrease in cropland area (73 %) and trail length (62.5 %) was also observed. Concerning the effect of donkey grazing, biomass was lower in pastures with grazing donkeys, with NDVI values decreasing once donkeys started grazing. Nevertheless, plant diversity was higher in pastures with grazing donkeys than in abandoned pastures. This study demonstrated the capacity of low-to-moderate-intensity donkey grazing to improve plant diversity and reduce biomass in pastures. Furthermore, the study of land use changes allowed an understanding of landscape dynamics, which can help address the social and environmental recovery of the village.

Escaping Neobiota: Habitat use and avoidance by sloth bears in Jessore Sloth bear Sanctuary India

Global terrestrial ecosystem is threatened by several factors, such as infestation of invasive plants, which influence the habitat use by wildlife. Prosopis juliflora is such a plant species, sprawled over arid and semiarid ecosystems in India. Under this study, we assumed that intensification of P. juliflora negatively affects the habitat used by sloth bears Melursus ursinus, along with geographical, ecological and anthropogenic predictors in Jessore Sloth bear Sanctuary, Gujarat, India. To inquire so, we conducted sign surveys (1 km trail length in each grid) in three seasons, i.e., winter, summer and monsoon. Further, the presence/absence of species’ signs was logistically modelled with elevation, terrain ruggedness, area proportions of dense forest, open scrub, P. juliflora infested area and human encroachment with respect to the seasons. We found that the area proportion of P. juliflora negatively affects habitat use by sloth bears, while elevation, terrain ruggedness, and area proportions of dense forest and open scrub positively trigger. The proportion of encroachment varied between the seasons. Further, we inferred the human-sloth bear encounter probability from the seasonal models. During summer, followed by winter, we evidenced the relatively high probability of bear occurrence around settlements, which can be advocated by the availability of food items around villages. The current study supports the prescribed ecology of sloth bears in semiarid regions in the Indian subcontinent. The study recommends the appropriate urgent management to arrest the conversion of native forest and scrub covers to P. juliflora dominant cover, thereby avoiding probabilistic human-sloth bear encounters.

Impact of Altitude on Population Structure and Distribution of Assamese Macaque (Macaca assamensis Mc’clelland, 1840) in Dampa Tiger Reserve in Mizoram, India

A study on population status and distribution of Assamese macaque ( Macaca assamensis ) across altitudinal gradients in Dampa Tiger Reserve (DTR), Mizoram, India was conducted. Six species of diurnal primates inhabits in DTR and a study on Assamese macaque is reported here. Line transact method was adopted for population sampling. Total distance covered was 293.5 km. Data on group locations, demography and site covariates including trail length, duration of walk, forest type were recorded. Nine groups of Assamese macaque comprising of 123 individuals were recorded mostly at an altitude between 250 m to 856 m. The smallest group was consisted of 7 individuals, and the largest was of 21 individuals. An average group size calculated was 13.6 (±4.32) individuals. The population comprised of 36.59% male, 53.66% female, and 9.76% immature. All the groups were comprised of multi-males and multi-females. The population encounter rate was 0.42 individual/km and the group encounter rate was 0.03group/ km. Total male to female ratio was 1:1.46, adult adult male to female ratio was 1:1.53. All female to immature ratio was 1:0.18 and an adult female to immature ratio was 1:0.26. Maximum sighting were at the distance between 30-50 m. Area of occupancy of groups was about 26 km 2 and ecological density was 4.7/ km 2 . Among primates in DTR, wild population of Assamese macaques were found to occupy altitudinal range between 250 to 856 m. 67% individuals were distributed at the altitude between 400 to 600 m. Presence of other primate species in DTR restricted the occurrence of this species.

Impact of Altitude on Population Structure and Distribution of Assamese Macaque (Macaca assamensis Mc’clelland, 1840) in Dampa Tiger Reserve in Mizoram, India

A study on population status and distribution of Assamese macaque ( Macaca assamensis ) across altitudinal gradients in Dampa Tiger Reserve (DTR), Mizoram, India was conducted. Six species of diurnal primates inhabits in DTR and a study on Assamese macaque is reported here. Line transact method was adopted for population sampling. Total distance covered was 293.5 km. Data on group locations, demography and site covariates including trail length, duration of walk, forest type were recorded. Nine groups of Assamese macaque comprising of 123 individuals were recorded mostly at an altitude between 250 m to 856 m. The smallest group was consisted of 7 individuals, and the largest was of 21 individuals. An average group size calculated was 13.6 (±4.32) individuals. The population comprised of 36.59% male, 53.66% female, and 9.76% immature. All the groups were comprised of multi-males and multi-females. The population encounter rate was 0.42 individual/km and the group encounter rate was 0.03group/ km. Total male to female ratio was 1:1.46, adult adult male to female ratio was 1:1.53. All female to immature ratio was 1:0.18 and an adult female to immature ratio was 1:0.26. Maximum sighting were at the distance between 30-50 m. Area of occupancy of groups was about 26 km 2 and ecological density was 4.7/ km 2 . Among primates in DTR, wild population of Assamese macaques were found to occupy altitudinal range between 250 to 856 m. 67% individuals were distributed at the altitude between 400 to 600 m. Presence of other primate species in DTR restricted the occurrence of this species.

Influence of contact parameters on the coupling temperature of copper-brass electrical contacts

The overheating phenomenon of slip ring will lead to wear failure of friction pair, and further affect the current-carrying efficiency. In order to study the temperature properties of slip ring, a friction and wear model with electric currents applied was established by COMSOL. The accuracy of the simulation was verified by the experiments. The distribution of coupling temperature field, and the influence of sliding speed, electric current density and contact pressure on the coupling temperature were studied. A phenomenon of “high temperature tailing” appears behind the contact area, and the trail length increases gradually with the time. The coupling temperature increases with electric current densities and sliding speeds. The MCT decreases rapidly at first and then increases gradually with the increase of contact pressure. There exists an optimal contact pressure to minimize the MCT. The optimal contact pressure increases with electric current densities, and decreases with sliding speed. The results may provide a theoretical basis for the temperature rise analysis and can improve the current-carrying efficiency of wind power slip ring.

Tick trails: the role of online recreational trail reviews in identifying risk factors and behavioral recommendations associated with tick encounters in Indiana

BackgroundRecreational trails abound across the United States and represent high risk areas for tick exposure. Although online reviews represent a rich source of user information, they have rarely been used in determining the risk of tick exposure during recreational trail use. Based on online user reviews and comments, the purpose of this study was to determine risk factors and behavioral recommendations associated with tick encounters (Tick Presence) on recreational trails in the state of Indiana, U.S.MethodsWe reviewed 26,016 user comments left on AllTrails.com for 697 Indiana trails. Reviews were evaluated to determine Tick Presence/Absence, the total number of Tick Presence Reviews per trail, and multiple trail and user behavioral characteristics. We used hot spot (Getis-Ord Gi*) analysis to test the hypothesis of whether there are clusters in the number of Tick Presence Reviews. Pearson chi-square tests of independence evaluated whether tick presence was associated with several trail characteristics. Finally, negative binomial regression evaluated the strength of the association between the number of Tick Presence Reviews and several trail characteristics.ResultsTick Presence was recorded at 10% (n = 65) of trails and occurred most frequently in May. Hot spot analysis revealed statistically significant clusters of Tick Presence Reviews on trails in the Southern Indiana State Region. Results of χ2 tests indicated significant associations between Tick Presence Reviews and (a) State Region and (b) Land Management Type; Mann-Whitney U tests detected significant differences in Tick Presence Reviews based on Trail Length and Elevation Gain. Subsequent results of a negative binomial regression model indicated that Southern Indiana State Region, Federal and Private Land Management Type, and Elevation Gain were factors significantly associated with Tick Presence Reviews. Content of user reviews indicated several behaviors employed to prevent tick encounters, particularly Repellent Application and Recreational Deterrence; 25% included a behavior Recommendation to others.ConclusionsOnline, user-generated trail reviews have the potential to serve as rich data sources for identifying recreational trails, where 1) the risk of tick exposure is great, 2) more robust active tick and tick-borne pathogen surveillance may be warranted, and 3) tailored prevention interventions are needed.

Hunting and the re-emergence of Human African Trypanosomiasis (HAT) in Bipindi (South Cameroon)

Background: Hunting activities play an important role in the survival and subsistence of the population. During hunting activities, trappers go into the bush and end up in the same biotopes with wild animals and flies, vectors of various diseases; they can accidently get involved in the wild transmission cycle of diseases maintained by vectors and wild animal, potential reservoir hosts. Many researchers reported a tight link between hunting activities and the emergence of some infectious diseases in forest areas. In order to investigate the role of hunting in the re-emergence human African trypanosomiasis (HAT), five active hunters have been followed during their hunting activities for one year; while G. palpalis palpalis were trapped in the same habitats. Methods and materials: 127 households in the Bipindi subdivision were systematically interviewed about their forest-related activities and 5 active trappers were selected according to trapping zones, hunting methods, snare trail length, trapping seasons, the time spent in each trapping zones per day to set traps, fences or renew traps and followed daily in their activities. Moreover, concerning entomological survey, 225 Vavoua traps were set up year-round in all trapping zones to inventory, determine the distribution and densities of tsetse flies. Results: The results showed that there are two hunting techniques used in the Bipindi area: foot snares mainly set in the undisturbed forest and neck snares mostly used on fences in farmlands. The total time spent by hunters in farmlands for neck snare trapping was higher compared to other trapping zones; while the time employed in foot snare trapping in the undisturbed forest was higher compared to other habitats. The mean snare trail length varied significantly between trapping sites (χ2 = 15.421; p = 0.001) and seasons (χ2 = 39.897; p = 0.0001) and Glossina palpalis palpalis the most abundant tsetse fly species recorded in the Bipindi area occurred in all trapping zones with an apparent density although unsignificantly different between trapping zones (χ2 = 5.956; p = 0.051) was highest in farmlands. Conclusion: Hunters are exposed to the bites of probable infective G. palpalis palpalis in all trapping zones although farmlands are the most risky transmission zones of sleeping sickness for trappers.

The Long‐Lived and Recent Seismicity at the Lunar Orientale Basin: Evidence From Morphology and Formation Ages of Boulder Avalanches, Tectonics, and Seismic Ground Motion

AbstractThe geologic analysis of lunar tectonic and co‐existing mass wasting features provides important insights into seismicity, seismic ground motion, and the seismic risk of the landed missions. Hence, we performed a detailed geologic mapping of tectonic features and co‐seismic boulder avalanches present at the 930‐km‐diameter lunar Orientale basin. We traced 6869 boulder falls at 141 sites along the basin rings, impact crater walls, and volcanic features. The boulder fields also occur on the graben walls and wrinkle ridges. The boulder trail length and width, and slopes of trail and source region of fallen boulders provide insights into formation processes and transport dynamics. Tens of sites have anomalously larger number of boulder falls and trail density. The cumulative size‐frequency distributions of superimposed impact craters present on the boulder trails provided their model formation ages varying between present and 7.5 Ma with at least eight formation episodes, suggesting the timings of seismic activities along the Cordillera and Outer Rook Rings. Many boulder falls are devoid of superimposed impact craters suggesting their recent origins, including some possibly triggered by the 1972 (MW 2.7) shallow moonquake that occurred near the Cordillera Ring. The formation rates of shallow moonquakes and impact craters along with the seismic ground motion simulations suggest that shallow moonquakes are more dominant sources of ground shaking for triggering the boulder falls in the last 30 million years. Therefore, the Orientale basin has been seismically active for long time and it may be seismically hazardous locally for the future landed missions.

Ecological Determinants of Occupancy and Abundance of Chinkara (<i>Gazella bennettii</i>) in Yadahalli Wildlife Sanctuary, Karnataka, India

Chinkara (Gazella bennettii), the Indian gazelle, is a widespread antelope in the arid and semi-arid regions of the Indian subcontinent; however, the species has been relatively unexplored to the south of its distribution range. In 2016, with indefinite evidence of chinkara presence in Yadahalli Reserved Forest, Karnataka, India, the Forest Department notified the area as a Wildlife Sanctuary (WLS). We conducted a study to explore their possible existence and population status at Yadahalli WLS using a novel approach. We laid 2 sq. km grid cells in the Yadahalli WLS and divided it into four replicated sub-grids using GPS. We walked the grid cells and recorded the chinkara midden and deployed camera traps for direct detection and individual identity. We recorded site covariates, i.e. tree density, tree diversity, basal area, food tree density, cattle dung, goat and sheep droppings and distance from the boundary, and detection covariates, i.e. trail length. We performed occupancy modelling based on midden recordings using PRESENCE ver. 5.3. Through the effort of 62 grids with four spatial replicates, the detection probability of chinkara was found to be 0.68 +/- 0.03(SE), and the estimated averaged occupancy was 0.51 +/- 0.37(SE). The present study reveals a potential population of similar to 85 individuals in the Yadahalli WLS, which is the known southernmost population of the species in India. This study establishes the use of novel methods for monitoring of chinkara populations which will help in the development of a conservation action plan for the species and its habitat.

Ecological trails in the specially protected natural areas of Altai Krai

The present paper provides results of studying the dynamics of ecological trails development in specially protected natural areas of Altai Krai. The study revealed the average number of the trails visitors, trail length, information content for educating students. Recommendations are given on the further development of this focus area and regular effective work on ecological trails. The authors identified the most attended ecological trails, studied the activities for schoolchildren and tourists on specially equipped trails in the wild. The article also examines the impact of the trails development on the environmental education of schoolchildren and the research work of students of the Department of Recreational Geography, Tourism and Regional Marketing of Altai State University (Geography Department) while developing the environmental routes.

Sediment Availability and Erosion Rates on Off‐Highway Vehicle Trails in the Ouachita Mountains, USA

AbstractFactors influencing sediment availability are assessed and erosion rates are quantified for an off‐highway vehicle (OHV) trail system in the Ouachita Mountains of Arkansas. As of May 2012, the Wolf Pen Gap trail system included 77.0 km of "trails" which consist of county roads; open and closed Forest Service roads; and open and closed OHV trails. For a given trail length, the sediment volume available to be eroded is determined by bare trail width and sediment depth. Four condition types are defined that group trail sections based on statistically different trail widths or depths. Trail construction method appears to influence sediment availability differences more than erosion potential (as indexed by trail slope gradient and length). The range for annual trail erosion rates is estimated as 75 and 210 tonne/ha/yr. The high and low rates are obtained using two independent methods. The 210 tonne/ha/yr rate is computed from mean sediment capture at 30 sediment traps installed for 0.5–1.0 year. The 75 tonne/ha/yr rate is computed assuming all available trail sediment measured in a one‐time sampling is eroded over the next year. We argue in support of this assumption and suggest both rate values may be conservative. Trail erosion rates and sediment trap observations indicate frequent trap cleanout will be needed to continue sediment capture from All Terrain Vehicle trails.

Factors influencing park popularity for mountain bikers, walkers and runners as indicated by social media route data

For most protected areas visitor data is limited, even for popular activities such as mountain biking, walking and running. With the exponential increase in volunteered geographic information, it is now possible to assess visitation to parks by people using social media. The number of routes posted to MapMyFitness, Strava and Wikiloc were used to assess the relative popularity of 40 national parks in South East Queensland, Australia for mountain biking, walking and running. Then, using generalised linear models, the topographic, geographic, management and environmental variables that best predicted park popularity among users were identified. There were more than 450,000 visits to the parks, with 98% of routes posted on Strava. Distance (road and direct distance) from large urban areas best predicted visitation using routes from MapMyFitness and Strava with three parks within 2 km of urban areas experiencing over 70,000 visits (Strava). For urban parks, recreational trail length best predicted usage, while for more remote parks, the direct distance to urban areas remained the most important factor. In contrast, people using the adventure platform Wikiloc preferred more remote parks with rugged terrain. The results highlight factors affecting park popularity including distance. With the expansion and densification of cities, including in Australia, urban and peri-urban parks are likely to experience increasing levels of use for fitness-based activities while more remote parks may remain attractive among people focused on adventure.

Stochastic models of polymerization-based axonal actin transport

Recent advances in live cell imaging of F-actin structures, combined with pulse-chase imaging and computational modeling have suggested that actin is transported along the axon via biased polymerization of metastable actin fibers (actin trails). This mechanism is distinct from motor driven polymer transport, such as for neurofilaments and can be best described as molecular hitchhiking, where G-actin molecules are intermittently incorporated into actin fibers which grow preferentially in the anterograde direction. In this paper, we discuss how various axonal and actin trail parameters like axon diameter, trail nucleation rates, basal G-actin concentration, and trail length influence the transport rate. These predictions can help guide future experiments to verify this novel protein transport mechanism. We introduce a simplified, analytically solvable model of actin transport which relates these parameters to experimentally measurable quantities. We also discuss why a simple diffusion-based transport mechanism cannot explain bulk actin transport in the axon.

Assessing the tourism carrying capacity of hiking trails in the Szczeliniec Wielki and Błędne Skały in Stołowe Mts. National Park

AbstractThe objective of this study was to determine the tourism carrying capacity on hiking trails in the Szczeliniec Wielki and Błędne Skały. Those attractions are located in the Stołowe Mts. National Park of the Sudetes in the South-Western part of Poland along the border with the Czech Republic. The total area of the Stołowe Mts. NP is 6,340 ha and it contains around 100 km of marked hiking trails. Tourist traffic in the Szczeliniec Wielki and Błędne Skały has its peaks during weekends and holiday periods reaching mass tourism scales. For this reason it is important to establish a clear tourism carrying capacity and to ensure this capacity is not exceeded. In this study, tourism carrying capacity was estimated based on trail width measurements and observations on the visitors’ behavior on trails. As a result an optimal distance between the visitors on a hiking trail was determined to be 4 meters of trail length per person. Whether the tourist carrying capacity was exceeded, was determined by calculating an index based on visitor data collected through the Monitoring System of tourist traffic (MStt). The MStt system consists of 38 infrared traffic counters (pyro-electric sensors) installed at the tourist trail entrances within the Stołowe Mts. National Park borders. Visitor data were aggregated into daily, monthly and annual reports, taking into account the direction of the visitors traffic on the studied hiking trails, i.e., entries only (IN), exits only (OUT) and total passings (IN+OUT). The tourist flow in Stołowe Mts. NP was characterized by its strong fluctuations over time with the carrying capacity index being exceeded only during long weekends and holiday periods. Additionally, the peak in traffic occurred around midday in spring and summer months. During those periods, the average traffic exceeded the hourly tourism carrying capacity by ca. 30%. Significant differences in tourist traffic were due the variability in visitor numbers, time of peak traffic and the dynamics of visitor numbers.

Open-Closed-Loop Iterative Learning Control for Linear Systems With Iteratively Variable Trail Lengths

This paper addresses the open-closed-loop iterative learning control (ILC) issue for linear systems with iteratively variable trail lengths. Due to the varying trail lengths in iteration domain, some tracking information would be lost at the previous iterations. To compensate the absent information, an open-closed-loop ILC scheme composing of a feed-forward ILC part and a feedback control part is designed. The convergence of ILC tracking error in mathematical expectation sense is guaranteed by the feed-forward part. The tracking information of the current iteration is employed by feedback control part to compensate the missing tracking information at the previous iterations. To deal with the iteratively variable trail lengths, a modified tracking error at desired trail length is adopted in the designed ILC scheme. It is shown that the mathematical expectation of tracking error is convergent to zero. Two illustrative examples are carried out to show the effectiveness of the proposed ILC schemes.

Iterative Learning Control for Linear Discrete-Time Systems with Randomly Variable Input Trail Length

For linear discrete-time systems with randomly variable input trail length, a proportional- (P-) type iterative learning control (ILC) law is proposed. To tackle the randomly variable input trail length, a modified control input at the desirable trail length is introduced in the proposed ILC law. Under the assumption that the initial state fluctuates around the desired initial state with zero mean, the designed ILC scheme can drive the ILC tracking errors to zero at the desirable trail length in expectation sense. The designed ILC algorithm allows the trail length of control input which is different from system state and output at a specific iteration. In addition, the identical initial condition widely used in conventional ILC design is also mitigated. An example manifests the validity of the proposed ILC algorithm.

Detection of tundra trail damage near Barrow, Alaska using remote imagery

In the past several decades, the use of all-terrain vehicles (ATVs) has proliferated in many Arctic communities in North America. One example is the village of Barrow, Alaska. This coastal community has only local roads, so all access to the interior utilizes off-road machines. These 4-wheel vehicles are the primary means of tundra traverse and transport in summer by hunters and berry-pickers, and by village residents accessing summer camps. Traveling cross-country is difficult due to the large number of thermokarst lakes, wetlands, and streams, and tundra trails tend to follow dryer higher ground while avoiding areas of high microrelief such as high-centered ice-wedge polygons. Thus, modern ATV trails tend to follow the margins of drained or partially drained thermokarst lake basins where it is flat and relatively dry, and these trails are heavily used. The deeply-ribbed tires of the heavy and powerful ATVs cause damage by destroying the vegetation and disturbing the underlying organic soil. Exposure of the dark soil enhances summer thaw and leads to local thermokarst of the ice-rich upper permafrost. The damage increases over time as vehicles continue to follow the same track, and sections eventually become unusable; this is especially true where the trail crosses ice-wedge troughs. Deep subsidence in the ponded troughs results in ATV users veering to avoid the wettest area, which leads to a widening of the damaged area. Helicopter surveys, site visits, and collection of ground penetrating radar data were combined with time series analysis of high-resolution aerial and satellite imagery for the period 1955–2014. The analysis reveals that there are 507km of off-road trails on the Barrow Peninsula. About 50% of the total trail length was developed before 1955 in association with resource extraction, and an additional 40% were formed between 1979 and 2005 by ATVs. Segments of the more modern trail are up to 100m wide. Damage to the tundra is especially pronounced in wet areas, such as ice-wedge troughs. Knowledgeable indigenous people are aware of the problem. Some remediation has been attempted by using heavy-duty PVC matting in areas of greatest damage, but this approach is prohibitively expensive on a large scale.

TRIPPy: TRAILED IMAGE PHOTOMETRY IN PYTHON

ABSTRACT Photometry of moving sources typically suffers from a reduced signal-to-noise ratio (S/N) or flux measurements biased to incorrect low values through the use of circular apertures. To address this issue, we present the software package, TRIPPy: TRailed Image Photometry in Python. TRIPPy introduces the pill aperture, which is the natural extension of the circular aperture appropriate for linearly trailed sources. The pill shape is a rectangle with two semicircular end-caps and is described by three parameters, the trail length and angle, and the radius. The TRIPPy software package also includes a new technique to generate accurate model point-spread functions (PSFs) and trailed PSFs (TSFs) from stationary background sources in sidereally tracked images. The TSF is merely the convolution of the model PSF, which consists of a moffat profile, and super-sampled lookup table. From the TSF, accurate pill aperture corrections can be estimated as a function of pill radius with an accuracy of 10 mmag for highly trailed sources. Analogous to the use of small circular apertures and associated aperture corrections, small radius pill apertures can be used to preserve S/Ns of low flux sources, with appropriate aperture correction applied to provide an accurate, unbiased flux measurement at all S/Ns.