changing landscapes, human impact on

2019 ◽  
Author(s):  
John Bintliff
Keyword(s):  
Human Impact ◽  
Land Surface ◽  
Agricultural Technology ◽  
Short Term ◽  
Rural Landscapes ◽  
Natural Factors ◽  
Classical World ◽  
Ancient Society ◽  
Shed Light

The Classical world witnessed many forms of physical landscape change due to long-term and short-term geological and climatological processes. There have also been alterations to the land surface resulting from an interaction between human impact and these natural factors. Cyclical changes in land use, agricultural technology, economy, and politics have continually transformed the rural landscapes of the Mediterranean and the wider Classical world and their mapping, in turn, can shed light on fundamental aspects of ancient society that are not always documented in Classical texts.

scholarly journals Learning Long- and Short-Term User Literal-Preference with Multimodal Hierarchical Transformer Network for Personalized Image Caption

2020 ◽  
Vol 34 (05) ◽  
pp. 9571-9578 ◽  
Author(s):  
Wei Zhang ◽  
Yue Ying ◽  
Pan Lu ◽  
Hongyuan Zha
Keyword(s):  
State Of The Art ◽  
Natural Extension ◽  
Target Image ◽  
Short Term ◽  
Image Representations ◽  
High Level ◽  
Image Descriptions ◽  
Shed Light ◽  
Image Caption

Personalized image caption, a natural extension of the standard image caption task, requires to generate brief image descriptions tailored for users' writing style and traits, and is more practical to meet users' real demands. Only a few recent studies shed light on this crucial task and learn static user representations to capture their long-term literal-preference. However, it is insufficient to achieve satisfactory performance due to the intrinsic existence of not only long-term user literal-preference, but also short-term literal-preference which is associated with users' recent states. To bridge this gap, we develop a novel multimodal hierarchical transformer network (MHTN) for personalized image caption in this paper. It learns short-term user literal-preference based on users' recent captions through a short-term user encoder at the low level. And at the high level, the multimodal encoder integrates target image representations with short-term literal-preference, as well as long-term literal-preference learned from user IDs. These two encoders enjoy the advantages of the powerful transformer networks. Extensive experiments on two real datasets show the effectiveness of considering two types of user literal-preference simultaneously and better performance over the state-of-the-art models.

scholarly journals The Influence of Atlantic Tropical Cyclones on Drought over the Eastern United States (1980–2007)

2013 ◽  
Vol 26 (10) ◽  
pp. 3067-3086 ◽  
Author(s):  
Jonghun Kam ◽  
Justin Sheffield ◽  
Xing Yuan ◽  
Eric F. Wood
Keyword(s):  
United States ◽  
Soil Moisture ◽  
Tropical Cyclones ◽  
Land Surface ◽  
Hydrologic Model ◽  
Eastern United States ◽  
Short Term ◽  
Drought Duration ◽  
Study Region

Abstract To assess the influence of Atlantic tropical cyclones (TCs) on the eastern U.S. drought regime, the Variable Infiltration Capacity (VIC) land surface hydrologic model was run over the eastern United States forced by the North American Land Data Assimilation System phase 2 (NLDAS-2) analysis with and without TC-related precipitation for the period 1980–2007. A drought was defined in terms of soil moisture as a prolonged period below a percentile threshold. Different duration droughts were analyzed—short term (longer than 30 days) and long term (longer than 90 days)—as well as different drought severities corresponding to the 10th, 15th, and 20th percentiles of soil moisture depth. With TCs, droughts are shorter in duration and of a lesser spatial extent. Tropical cyclones variously impact soil moisture droughts via late drought initiation, weakened drought intensity, and early drought recovery. At regional scales, TCs decreased the average duration of moderately severe short-term and long-term droughts by less than 4 (10% of average drought duration per year) and more than 5 (15%) days yr−1, respectively. Also, they removed at least two short-term and one long-term drought events over 50% of the study region. Despite the damage inflicted directly by TCs, they play a crucial role in the alleviation and removal of drought for some years and seasons, with important implications for water resources and agriculture.

Notes on the rural landscape of central Tyrrhenian Italy in the 6th-5th c. b.c. and its social significance

2002 ◽  
Vol 15 ◽  
pp. 247-260 ◽  
Author(s):  
Gabriele Cifani
Keyword(s):  
Interdisciplinary Approach ◽  
Rural Landscape ◽  
Environmental Archaeology ◽  
Social Significance ◽  
Short Term ◽  
Rural Landscapes ◽  
Landscape Studies ◽  
Art Historians ◽  
Two Sides

During the last few decades most landscape archaeologists have noted the diffusion and the demographic importance of the rural landscapes of Archaic Etruscan communities and have tried to define their significance within Etruscan society in the same way as others have attempted to evaluate the political significance of the Greek rural landscape. Recent research on Italian landscapes has led to a great increase in the available data regarding the different paths of development for the various communities, allowing them to be outlined and compared.The growing dichotomy between the studies of field archaeologists and historians or art-historians may appear to be a problem. Landscape studies in Italy have been dominated since the 1950s by an Anglocentric tradition of economic and environmental archaeology, with important work focusing on long-term phenomena. Historians and art-historians, on the other hand, have tried to define an interdisciplinary approach involving the use of several sources of evidence (art-historical, epigraphic, literary) and focusing on historical events and medium-or short-term phenomena. Yet field and historical archaeology are simply two sides of the same coin, and should be viewed as complementary rather than incompatible approaches to understanding the comolex evidence of the Dre-Roman cultures.

Fifty years of Marine and Freshwater Research

1999 ◽  
Keyword(s):  
Coral Reefs ◽  
Sea Level ◽  
Climate Changes ◽  
Sea Water ◽  
Global Climate ◽  
Short Term ◽  
Natural Factors ◽  
Carbon Dioxide Concentrations ◽  
Minimal Damage

Factors causing global degradation of coral reefs are examined briefly as a basis for predicting the likely consequences of increases in these factors. The earlier consensus was that widespread but localized damage from natural factors such as storms, and direct anthropogenic effects such as increased sedimentation, pollution and exploitation, posed the largest immediate threat to coral reefs. Now truly global factors associated with accelerating Global Climate Change are either damaging coral reefs or have the potential to inflict greater damage in the immediate future: e.g. increases in coral bleaching and mortality, and reductions in coral calcification due to changes in sea-water chemistry with increasing carbon dioxide concentrations. Rises in sea level will probably disrupt human communities and their cultures by making coral cays uninhabitable, whereas coral reefs will sustain minimal damage from the rise in sea level. The short-term (decades) prognosis is indeed grim, with major reductions almost certain in the extent and biodiversity of coral reefs, and severe disruptions to cultures and economies dependent on reef resources. The long-term (centuries to millennia) prognosis is more encouraging because coral reefs have remarkable resilience to severe disruption and will probably show this resilience in the future when climate changes either stabilize or reverse.

Thermal Treatment Effects on a PLLA Bioresorbable Stent

2007 ◽  
Author(s):  
Tre Welch ◽  
Robert C. Eberhart ◽  
Cheng-Jen Chuong
Keyword(s):  
Vascular Endothelium ◽  
Vulnerable Plaque ◽  
Arterial Wall ◽  
Vascular Wall ◽  
Short Term ◽  
Endothelial Lining ◽  
Endothelial Surface ◽  
Bioresorbable Stent ◽  
Shed Light

Stent navigation and expansion may injure vascular endothelium, including vulnerable plaque lesions. Balloon expansion and deployment of a stent can lead to injury or the endothelial lining and stretching of the arterial wall [1]. Understanding the traction forces an expanding stent imparts on the vascular wall at the endothelial surface, the underlying plaque lesions and other tissue components during expansion is an important step in improving short term stent-wall mechanics. More importantly, the long term influence of stent-vascular wall mechanical interactions in restenosis remains unknown, and this analysis may shed light on the process.

scholarly journals Shallow groundwater thermal sensitivity to climate change and land cover disturbances: derivation of analytical expressions and implications for stream temperature projections

2014 ◽  
Vol 11 (11) ◽  
pp. 12573-12626 ◽  
Author(s):  
B. L. Kurylyk ◽  
K. T. B. MacQuarrie ◽  
D. Caissie ◽  
J. M. McKenzie
Keyword(s):  
Climate Change ◽  
Land Surface ◽  
Thermal Sensitivity ◽  
Shallow Groundwater ◽  
Stream Temperature ◽  
Heat Fluxes ◽  
Short Term ◽  
Surface Warming ◽  
Advection Diffusion Equation

Abstract. Climate change is expected to increase stream temperatures, and the projected warming may alter the spatial extent of habitat for coldwater fish and other aquatic taxa. Recent studies have proposed that stream thermal sensitivities, derived from short term air temperature variations, can be employed to infer future stream warming due to long term climate change. However, this approach does not consider the potential for streambed heat fluxes to increase due to gradual warming of shallow groundwater. The temperature of shallow groundwater is particularly important for the thermal regimes of groundwater-dominated streams and rivers. Also, other recent stream temperature studies have investigated how land surface perturbations, such as wildfires or timber harvesting, can influence stream temperatures by changing surface heat fluxes, but these studies have typically not considered how these surface disturbances can also alter shallow groundwater temperatures and consequent streambed heat fluxes. In this study, several analytical solutions to the one-dimensional unsteady advection–diffusion equation for subsurface heat transport are employed to investigate the timing and magnitude of groundwater warming due to seasonal and long term variability in land surface temperatures. Novel groundwater thermal sensitivity formulae are proposed that accommodate different surface warming scenarios. The thermal sensitivity formulae demonstrate that shallow groundwater will warm in response to climate change and other surface perturbations, but the timing and magnitude of the warming depends on the rate of surface warming, subsurface thermal properties, aquifer depth, and groundwater velocity. The results also emphasize the difference between the thermal sensitivity of shallow groundwater to short term (e.g. seasonal) and long term (e.g. multi-decadal) land surface temperature variability, and thus demonstrate the limitations of using short term air and water temperature records to project future stream warming.

scholarly journals Potential caveats in Land Surface Model evaluations using the U.S. Drought Monitor: roles of base periods and drought indicators

2021 ◽  
Author(s):  
Hailan Wang ◽  
Li Xu ◽  
Mimi Hughes ◽  
Muthuvel Chelliah ◽  
David G DeWitt ◽  
...  
Keyword(s):  
Land Surface ◽  
Land Surface Model ◽  
Water Model ◽  
Drought Indices ◽  
Surface Model ◽  
Short Term ◽  
Sst Variability ◽  
Drought Occurrence ◽  
The U.S

Abstract The U.S. Drought Monitor (USDM) has been widely used as an observational reference for evaluating Land Surface Model (LSM) simulation of drought. This study investigates potential caveats in such evaluation when the USDM and LSMs use different base periods and drought indices to identify drought. The retrospective National Water Model (NWM) v2.0 simulation (1993-2018) was used to exemplify the evaluation, supplemented by North American Land Data Assimilation System Phase 2 (NLDAS-2). In distinct contrast with the USDM which shows high drought occurrence (>50%) in the western half of the continental U.S. (CONUS) and the southeastern U.S. with low occurrence (<30%) elsewhere, the NWM and NLDAS-2 based on soil moisture percentiles (SMPs) consistently show higher drought occurrence (30-40%) in the central and southeastern U.S. than the rest of the CONUS. Much of the differences between the LSMs and USDM, particularly the strong LSM underestimation of drought occurrence in the western and southeastern U.S., are not attributed to the LSM deficiencies, but rather the lack of long-term drought in the LSM simulations due to their relatively short lengths. Specifically, the USDM integrates drought indices with century-long periods of record, which enables it to capture both short-term (<6 months) drought and long-term (>=6 months) drought, whereas the relatively short retrospective simulations of the LSMs allows them to adequately capture short-term drought but not long-term drought. In addition, the USDM integrates many drought indices whereas the NWM results are solely based on the SMP, further adding to the inconsistency. The high occurrence of long-term drought in the western and southeastern U.S. in the USDM is further found to be driven collectively by the post-2000 long-term warm SST trend, cold Pacific Decadal Oscillation (PDO) and warm Atlantic Multi-decadal Oscillation (AMO), all of which are typical leading patterns of global Sea Surface Temperature (SST) variability that can induce drought conditions in the western, central, and southeastern U.S. Our findings highlight the effects of the above caveats and suggest that LSM evaluation should stay qualitative when the caveats are considerable.

scholarly journals Power-sharing, conflict resolution, and the logic of pre-emptive defection

2020 ◽  
pp. 002234332092469
Author(s):  
Chelsea Johnson
Keyword(s):  
Logistic Regression ◽  
Transition Period ◽  
Power Sharing ◽  
Short Term ◽  
Negotiated Settlements ◽  
Electoral Defeat ◽  
Commitment Problem ◽  
Shed Light ◽  
Cross National

Conclusions about the potential for peace via power-sharing are mixed. For some, power-sharing does little to overcome the commitment problem characterizing a transition from conflict, while others argue that such concessions provide signals of parties’ willingness to incur costs. This article develops and tests a new theory, aiming to shed light on the mechanisms through which power-sharing bargains help to overcome the commitment problem. I argue that government parties tend to hold an electoral and military advantage, which heightens incentives for rebel leaders to defect from a settlement prior to conceding their capacity to use violence. Where settlements provide discrete guarantees that offset the risks of electoral defeat and the co-optation of forces, these incentives for pre-emptive defection should be mitigated. I offer a novel disaggregation of provisional power-sharing subtypes, distinguishing between long-term and short-term arrangements. The analysis rests on an original, cross-national dataset of government-and-rebel dyads to negotiated settlements signed between 1975 and 2015 (N = 168). The logistic regression results clearly indicate that power-sharing settlements stipulating ‘consociational’-style reforms are significantly more likely to resolve conflict between settlement dyads, all else equal. Meanwhile, standard conceptualizations of power-sharing, which include transitional coalitions and troop integration, appear unlikely to secure rebel commitment beyond the transition period, which helps to explain the contradictory findings in existing research.

Global and local threats to coral reef functioning and existence: review and predictions

1999 ◽  
Author(s):  
Clive R. Wilkinson
Keyword(s):  
Coral Reefs ◽  
Sea Level ◽  
Sea Water ◽  
Global Climate ◽  
Short Term ◽  
Natural Factors ◽  
Carbon Dioxide Concentrations ◽  
Minimal Damage ◽  
Global And Local

Factors causing global degradation of coral reefs are examined briefly as a basis for predicting the likely consequences of increases in these factors. The earlier consensus was that widespread but localized damage from natural factors such as storms, and direct anthropogenic effects such as increased sedimentation, pollution and exploitation, posed the largest immediate threat to coral reefs. Now truly global factors associated with accelerating Global Climate Change are either damaging coral reefs or have the potential to inflict greater damage in the immediate future: e.g. increases in coral bleaching and mortality, and reductions in coral calcification due to changes in sea-water chemistry with increasing carbon dioxide concentrations. Rises in sea level will probably disrupt human communities and their cultures by making coral cays uninhabitable, whereas coral reefs will sustain minimal damage from the rise in sea level. The short-term (decades) prognosis is indeed grim, with major reductions almost certain in the extent and biodiversity of coral reefs, and severe disruptions to cultures and economies dependent on reef resources. The long-term (centuries to millennia) prognosis is more encouraging because coral reefs have remarkable resilience to severe disruption and will probably show this resilience in the future when climate changes either stabilize or reverse.

scholarly journals Shallow groundwater thermal sensitivity to climate change and land cover disturbances: derivation of analytical expressions and implications for stream temperature modeling

2015 ◽  
Vol 19 (5) ◽  
pp. 2469-2489 ◽  
Author(s):  
B. L. Kurylyk ◽  
K. T. B. MacQuarrie ◽  
D. Caissie ◽  
J. M. McKenzie
Keyword(s):  
Climate Change ◽  
Land Surface ◽  
Thermal Sensitivity ◽  
Shallow Groundwater ◽  
Stream Temperature ◽  
Heat Fluxes ◽  
Short Term ◽  
Surface Warming ◽  
Advection Diffusion Equation

Abstract. Climate change is expected to increase stream temperatures and the projected warming may alter the spatial extent of habitat for cold-water fish and other aquatic taxa. Recent studies have proposed that stream thermal sensitivities, derived from short-term air temperature variations, can be employed to infer future stream warming due to long-term climate change. However, this approach does not consider the potential for streambed heat fluxes to increase due to gradual warming of the shallow subsurface. The temperature of shallow groundwater is particularly important for the thermal regimes of groundwater-dominated streams and rivers. Also, recent studies have investigated how land surface perturbations, such as wildfires or timber harvesting, can influence stream temperatures by changing stream surface heat fluxes, but these studies have typically not considered how these surface disturbances can also alter shallow groundwater temperatures and streambed heat fluxes. In this study, several analytical solutions to the one-dimensional unsteady advection–diffusion equation for subsurface heat transport are employed to estimate the timing and magnitude of groundwater temperature changes due to seasonal and long-term variability in land surface temperatures. Groundwater thermal sensitivity formulae are proposed that accommodate different surface warming scenarios. The thermal sensitivity formulae suggest that shallow groundwater will warm in response to climate change and other surface perturbations, but the timing and magnitude of the subsurface warming depends on the rate of surface warming, subsurface thermal properties, bulk aquifer depth, and groundwater velocity. The results also emphasize the difference between the thermal sensitivity of shallow groundwater to short-term (e.g., seasonal) and long-term (e.g., multi-decadal) land surface-temperature variability, and thus demonstrate the limitations of using short-term air and water temperature records to project future stream warming. Suggestions are provided for implementing these formulae in stream temperature models to accommodate groundwater warming.

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