In the former “Eastern Bloc” countries, there have been dramatic changes in forest disturbance and forest recovery rates since the collapse of the Soviet Union, due to the transition to open-market ...economies, and the recent economic crisis. Unfortunately though, Eastern European countries collected their forest statistics inconsistently, and their boundaries have changed, making it difficult to analyze forest dynamics over time. Our goal here was to consistently quantify forest cover change across Eastern Europe since the 1980s based on the Landsat image archive. We developed an algorithm to simultaneously process data from different Landsat platforms and sensors (TM and ETM+) to map annual forest cover loss and decadal forest cover gain. We processed 59,539 Landsat images for 527 footprints across Eastern Europe and European Russia. Our results were highly accurate, with gross forest loss producer's and user's accuracy of >88% and >89%, respectively, and gross forest gain producer's and user's accuracy of >75% and >91%, based on a sample of probability-based validation points. We found substantial changes in the forest cover of Eastern Europe. Net forest cover increased from 1985 to 2012 by 4.7% across the region, but decreased in Estonia and Latvia. Average annual gross forest cover loss was 0.41% of total forest cover area, with a statistically significant increase from 1985 to 2012. Timber harvesting was the main cause of forest loss, accompanied by some insect defoliation and forest conversion, while only 7.4% of the total forest cover loss was due to large-scale wildfires and windstorms. Overall, the countries of Eastern Europe experienced constant levels or declines in forest loss after the collapse of socialism in the late 1980s, but a pronounced increase in loss in the early 2000s. By the late 2000s, however, the global economic crisis coincided with reduced timber harvesting in most countries, except Poland, Czech Republic, Slovakia, and the Baltic states. Most forest disturbance did not result in a permanent forest loss during our study period. Indeed, forest generally recovered fast and only 12% of the areas of forest loss prior to 1995 had not yet recovered by 2012. Our results allow national and sub-national level analysis and are available on-line (http://glad.geog.umd.edu/europe/) to serve as a baseline for further analyses of forest dynamics and its drivers.
•Annual quantification of forest dynamics for 27years performed with high accuracy•Results show spatial and temporal variation of forest cover change.•Wall-to-wall forest dynamics maps available at http://glad.geog.umd.edu/europe/•Overall, forest cover increased by 4.7%, but decreased in some regions.•Forest dynamics mirrored the collapse of the USSR and the recent economic crisis.
Tropical forests provide global climate regulation ecosystem services and their clearing is a significant source of anthropogenic greenhouse gas (GHG) emissions and resultant radiative forcing of ...climate change. However, consensus on pan-tropical forest carbon dynamics is lacking. We present a new estimate that employs recommended good practices to quantify gross tropical forest aboveground carbon (AGC) loss from 2000 to 2012 through the integration of Landsat-derived tree canopy cover, height, intactness and forest cover loss and GLAS-lidar derived forest biomass. An unbiased estimate of forest loss area is produced using a stratified random sample with strata derived from a wall-to-wall 30 m forest cover loss map. Our sample-based results separate the gross loss of forest AGC into losses from natural forests (0.59 PgC yr−1) and losses from managed forests (0.43 PgC yr−1) including plantations, agroforestry systems and subsistence agriculture. Latin America accounts for 43% of gross AGC loss and 54% of natural forest AGC loss, with Brazil experiencing the highest AGC loss for both categories at national scales. We estimate gross tropical forest AGC loss and natural forest loss to account for 11% and 6% of global year 2012 CO2 emissions, respectively. Given recent trends, natural forests will likely constitute an increasingly smaller proportion of tropical forest GHG emissions and of global emissions as fossil fuel consumption increases, with implications for the valuation of co-benefits in tropical forest conservation.
Search for a cheap and efficient route of graphene fabrication is still far from its conclusion, and reduction of graphene oxide (GO) is considered one of the most promising ways to achieve this ...goal. Here we perform combined experimental and computational analysis of a simple yet efficient and environment-friendly method for reducing GO using nanosecond infrared laser irradiation, which can be performed under ambient conditions and does not require an inert atmosphere or vacuum. We demonstrate that ultrafast heating up to 3800 K leads to a fascinating regime of high quality GO reduction even in the presence of atmospheric air. This surprising effect is achieved as an interplay between two seemingly opposite processes: combustion on the highly-defective areas of GO, such as grain boundaries, and defect annealing in its bulk part. As a result, under particular pulse regimes, after a small loss of mass (primarily from its edges), GO transforms into rGO with a high local order and low Raman I(D)/I(G) ratio.
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Bromination of
N
-acyl-2,2,4-trimethyl-1,2-dihydroquinolines with
N
-bromosuccinimide (NBS) in CCl
4
in the presence of Bz
2
O
2
proceeded at the 4-positioned methyl group. In a DMF solution, the ...direction of the reaction was determined by the nature of substituent at the nitrogen atom: the reaction with one equivalent of NBS can proceed either as described above, or at position 3 with the allylic rearrangement-type migration of the multiple bond. The use of two equimoles of NBS in DMF led to 3-bromo-4-bromometh-ylene-2,2-dimethyl-3,4-dihydroquinolines. The N- and S-alkylation reactions of 3- and 4-brominated isomers resulted in the same 4-
N
- and 4-
S
-methyl derivatives.
BACKGROUND AND AIMS:Pediatric ulcerative colitis (UC) shares many features with adult-onset disease but there are some unique considerations; therefore, therapeutic approaches have to be adapted to ...these particular needs. We aimed to formulate guidelines for managing UC in children based on a systematic review (SR) of the literature and a robust consensus process. The present article is a product of a joint effort of the European Crohnʼs and Colitis Organization (ECCO) and the European Society for Paediatric Gastroenterology, Hepatology, and Nutrition (ESPGHAN).
METHODS:A group of 27 experts in pediatric IBD participated in an iterative consensus process including 2 face-to-face meetings, following an open call to ESPGHAN and ECCO members. A list of 23 predefined questions were addressed by working subgroups based on a SR of the literature.
RESULTS:A total of 40 formal recommendations and 68 practice points were endorsed with a consensus rate of at least 89% regarding initial evaluation, how to monitor disease activity, the role of endoscopic evaluation, medical and surgical therapy, timing and choice of each medication, the role of combined therapy, and when to stop medications. A management flowchart, based on the Pediatric Ulcerative Colitis Activity Index (PUCAI), is presented.
CONCLUSIONS:These guidelines provide clinically useful points to guide the management of UC in children. Taken together, the recommendations offer a standardized protocol that allows effective, timely management and monitoring of the disease course, while acknowledging that each patient is unique.
AIM: Tropical forest degradation is a significant source of carbon emissions due to selective logging, fragmentation and other disturbance factors. However, methods for mapping and monitoring ...pan‐tropical forest degradation are still in their infancy. Here we present a new and automated approach to differentiate forests likely to be affected by degradation dynamics from more structurally intact forests, referred to as hinterland forests. LOCATION: Pan‐tropical. METHODS: Inputs required for hinterland forest mapping include the extent of the initial forest cover and subsequent forest cover loss data, in this case global‐scale Landsat‐derived tree cover and stand‐replacement disturbance maps. User‐defined parameters employed to generate the extent and change of hinterland forest include: (1) minimum size of hinterland forest patch, (2) minimum corridor width, (3) distance from disturbance, and (4) extant history. RESULTS: Hinterland forest extent was mapped using forest cover loss data from 2000 to 2012 and hinterland forest loss was quantified from 2007 to 2013. Lidar‐modelled forest height data were shown to be different within and outside hinterland forests, demonstrating the biophysical basis of the hinterland concept in discriminating likely degradation. Overall, hinterland forests experienced an 18% decline from 2007 to 2013. Regional variation in hinterland forest extent and loss was high. Data on 2013 pan‐tropical hinterland forest extent can be downloaded from http://glad.geog.umd.edu/hinterland/index.html and viewed online at http://earthenginepartners.appspot.com/science‐2013‐global‐forest. MAIN CONCLUSIONS: The largest extent of hinterland forests and of hinterland forest loss was found in Latin America, followed by Africa and Southeast Asia, respectively. The highest proportional loss of hinterland forest occurred in Southeast Asia, followed by Africa and Latin America, respectively. Nearly 95% of all 2013 hinterland forests were found in 17 of the 69 tropical forest countries studied. The extent and loss of hinterland forest can be an input to national monitoring and management programmes focused on forest carbon stocks, biodiversity conservation and other ecosystem services.
The paper deals with the main aspects of the technique for weight optimization of design parameters of sandwich shell-type composite structures with a honeycomb filler. This technique was implemented ...in the framework of the comprehensive approach proposed earlier for the integrated designing of assembly units of the equipment class considered. Multi-parameter problem of optimization of the parameters of sandwich shell-type composite structures was solved. The optimization process was divided into several stages in accordance with the reasonable levels of significance of the parameters included in the objective function, i.e., minimum weight. The results allow us to achieve a deep level of simultaneous optimization of the reinforcement pattern and structure of load-bearing skins, the height of the honeycomb filler, and the geometric parameters of its cell, as well as parameters of the additional structural frame in the regular zone and local reinforcement zones for almost all spectrum of external actions. At the same time, the load-bearing capacity of the structure was provided in all critical areas taking into account the deterioration of the physicomechanical characteristics of materials employed due to thermal effect and fulfilment of additional functional and technological constraints. Using an example of the interstage compartment of a launch rocket, implementation of the technique proposed for synthesis of its rational design and technology parameters was shown. Results of ground-based strength tests of the interstage compartment at this stage of development confirmed the reliability of the results obtained. The results taken as a whole form are the scientific basis for the rational design of sandwich shell-type systems with the honeycomb filler under simultaneous strength and thermal loadings, taking into account of technological constraints and can be used in designing of the other load-bearing shell-type units for aviation, space, and conversion applications.
A multidimensional system of ordinary differential equations with relay hysteresis is considered. The system parameters are assumed to be such that there exists a family of continuous operators each ...of which maps some connected compact set into itself. In this case, the operator corresponds to a periodic orbit with an even number of switching points in the phase space of the system. For the operator family, a necessary and sufficient condition for the existence of a single fixed point is obtained.
A second-order ordinary differential equation with a three-position hysteresis relay characteristic and a periodic perturbation function is considered. The existence theorem is proved for an ...oscillatory solution with a complete traversal of the characteristic with a possible exit into its saturation zones in some finite time and with a closed phase trajectory of an arbitrary shape. Sufficient conditions for the existence of periodic solutions with arbitrary and symmetric phase trajectories are established, as well as conditions for the nonexistence of a periodic solution with a symmetric phase trajectory. Numerical examples are given.
We consider an
-dimensional system of ordinary differential equations with relay hysteresis on the right-hand side. Under certain conditions, the solution of the system defines a self-mapping of ...bounded sets lying in the discontinuity surfaces. We obtain conditions for the existence of fixed points of the mapping and the uniqueness of the fixed point as well as conditions under which fixed points for various types of mappings exist simultaneously. To each type of mapping there corresponds one type of periodic orbits: either with two switching points (the so-called unimodal orbits) or with an even number of switching points greater than two. In the case of unimodal orbits, examples of the existence of orbits of various configurations are given.
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