不同气候变化情景下亚洲北山羊（Capra sibirica）的响应（英文）

目前很少见到关于气候变化影响亚洲北山羊物种栖息地的研究。通过调查气候变化对塔吉克斯坦东部亚洲北山羊(Capra sibirica)分布的影响,并采用生态位建模比较了亚洲北山羊的适宜栖息地的当前与未来分布情况。预计到2070年,现有适宜栖息地的18%(2689 km^2)将变得不适宜亚洲北山羊的生存,损失的区域主要位于研究区域的东南部和西北部地区。新的适宜栖息地可能会扩展到当前亚洲北山羊范围之外:到2070年将扩展30%(4595 km^2)的范围,这些区域与亚洲北山羊现有的分布有很强的相关性。东南部的损失与该地区当前大多数的亚洲北山羊栖息地重叠,主要出现在比研究区域海拔低得多的区域(3500–4000 m)。当同时考虑损失和收益时,亚洲北山羊可能会净扩展到新的适宜栖息地。到2070年,亚洲北山羊的平均栖息地增加量约为30%(1379 km^2),表明适宜栖息地已向北部低温栖息地转移。研究结果有助于规划气候变化情景下塔吉克斯坦东部山区对生物多样性保护的潜在影响。应该特别注意东南地区的高地山羊种群,那里的栖息地可能由于气候对山区生态系统的影响而变得不适合该物种继续生存。     

Criteria for recognizing shelf-slope clinoforms in outcrop; Jurassic Lajas and Los Molles formations,S. Neuquén Basin,Argentina

Seismic-reflection data show that most deepwater (>200 m water depth) basins are filled by sand and mud dispersed across clinoformal geometries characterized by gently dipping topsets, steeper foresets and gently dipping bottomsets. However, the entire geometry of these ubiquitous clinoforms is not always recognized in outcrops. Sometimes the infill is erroneously interpreted as “layer cake” or “ramp” stratigraphy because the topset-foreset-bottomset clinoforms are not well exposed. Regional 2-D seismic lines show clinoforms in the Lower to Middle Jurassic Challaco, Lajas, and Los Molles formations in S. Neuquén Basin in Argentina. Time equivalent shelf, slope and basin-floor segments of clinoforms are exposed, and can be walked out in hundreds of metres thick and kilometres-wide outcrops. The studied margin-scale clinoforms are not representing a continental-margin but a deepwater shelf margin that built out in a back-arc basin. Lajas-Los Molles clinoforms have been outcrop-mapped by tracing mudstones interpreted as flooding surfaces on the shelf and abandonment surfaces (low sedimentation rate) in the deepwater basin. The downslope and lateral facies variability in the outcrops is also consistent with a clinoform interpretation. The Lajas topset (shelf) is dominated by fluvial and tidal deposits. The shelf-edge rollover zone is occasionally occupied by a 40–50-m-thick coarse-grained shelf-edge delta, sometimes incising into the underlying slope mudstones, producing oblique clinoforms expressing toplap erosion on seismic. A muddy transgressive phase capping the shelf-edge deltas contains tidal sandbodies. Shelf-edge deltas transition downslope into turbidite- and debris flow-filled channels that penetrate down the mud-prone Los Molles slope. At the base-of-slope, some 300m below the shelf edge, there are basin-floor fan deposits (>200 m thick) composed of sandy submarine-fan lobes separated by muddy abandonment intervals. The large-scale outcrop correlation between topset–foreset–bottomset allows facies and depositional interpretation and sets outcrop criteria recognition for each clinoform segment.     

Optical and infrared photometry of new very low‐mass stars and brown dwarfs in the σ Orionis cluster

We present an RI photometric survey covering an area of 430 arcmin² around the multiple star σ Orionis. The observations were conducted with the 0.8 m IAC‐80 Telescope at the Teide Observatory. The survey limiting R and I magnitudes are 22.5 and 21, and completeness magnitudes 21 and 20, respectively. We have selected 53 candidates from the I vs. R–I colour‐magnitude diagram (I = 14–20) that follow the previously known photometric sequence of the cluster. Adopting an age of 2–4 Myr for the cluster, we find that these objects span a mass range from 0.35 M_⊙ to 0.015 M_⊙. We have performed J‐band photometry of 52 candidates and K_s photometry for 12 of them, with the result that 50 follow the expected infrared sequence for the cluster, thus confirming with great confidence that the majority of the candidates are bona fide members. JHK_s photometry from the Two Micron All Sky Survey (2MASS) is available for 50 of the candidates and are in good agreement with our data. Out of 48 candidates, which have photometric accuracies better than 0.1 mag in all bands, only three appear to show near‐infrared excesses. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Identifying Environmental and Human Factors Associated With Tick Bites using Volunteered Reports and Frequent Pattern Mining

Tick populations and tick‐borne diseases like Lyme borreliosis have been steadily increasing since the mid‐1990s. Realizing the threat that ticks pose to public health, two Dutch citizen science projects have collected tick bite reports since 2006. This unique volunteered geographical dataset, which currently has nearly 35,000 reports, was used to identify environmental and other circumstantial factors associated with tick bites. For this, we first enriched the tick bite reports with temperature, precipitation, vegetation and volunteered data associated with the location of the tick bite. Using this enriched dataset, we then derived a series of features to characterize the environmental and volunteer‐related conditions in which each tick bite occurred. Next, we discretized these features using the Jenks Natural Breaks algorithm and, after that, we mined frequent environmental patterns associated with tick bites using the AprioriClose algorithm. Finally, we checked that these patterns are specifically associated with the tick bites by comparing them with the frequent patterns mined from pseudo‐random locations. The frequent patterns were visualized using heat maps and ring maps and two representative patterns associated with tick bites were projected into geographic space to study their spatio‐temporal distribution. Our results show that factors linked to human activity are more relevant to model tick bites than seasonal accumulations of temperature, vegetation or precipitation. In particular, the number of warm and dry days per season are present in a significant number of patterns and the majority of tick bites are produced within a distance of half a kilometer of a forest, recreational or built‐up area. The study of patterns in the time‐series revealed that there are several persistent patterns consistently occurring each year and the validation process showed that the volunteer tick bites collection is capturing environmental conditions associated with tick bites, suggesting that these reports have a high scientific value. These results support the creation of a Dutch tick bite risk map that, in turn, will open the door to the design of public health interventions to reduce the incidence of Lyme disease.     

Validation of recent geopotential models in Tierra Del Fuego

This work presents a validation study of global geopotential models (GGM) in the region of Fagnano Lake, located in the southern Andes. This is an excellent area for this type of validation because it is surrounded by the Andes Mountains, and there is no terrestrial gravity or GNSS/levelling data. However, there are mean lake level (MLL) observations, and its surface is assumed to be almost equipotential. Furthermore, in this article, we propose improved geoid solutions through the Residual Terrain Modelling (RTM) approach. Using a global geopotential model, the results achieved allow us to conclude that it is possible to use this technique to extend an existing geoid model to those regions that lack any information (neither gravimetric nor GNSS/levelling observations). As GGMs have evolved, our results have improved progressively. While the validation of EGM2008 with MLL data shows a standard deviation of 35 cm, GOCO05C shows a deviation of 13 cm, similar to the results obtained on land.