Reproductive pattern and egg development of the deep-sea crab Paromola cuvieri (Brachyura,Homolidae) around the Canary Islands (NE Atlantic)

This work investigated the biology of Paromola cuvieri in the Atlantic Ocean, including reproductive patterns, sex structure, depth distribution and egg development. Females were more abundant than males, mainly at depths greater than 600 m. Males were dominant in size classes larger than 110 mm carapace width (CW), especially over 120 mm, for which only males were observed. The mean length of both sexes decreased with depth. P. cuvieri appears to have continuous reproduction throughout the year. Large females tend to spawn mainly between summer and winter, but smaller females spawn during the summer. Four maturity categories were identified based on the ovary colour, and these categories were histologically validated. Three categories of testes were identified according to their colour and morphology. Sexual maturity was estimated at sizes between 71.6 and 74.0 mm CW for females and at 91.0 mm CW for males. The relative growth showed changes along the ontogeny, at 73.6 mm CW (females) and 91.3–92.2 mm CW (males). Egg development appears to not be completely synchronous, and two colour patterns can be observed simultaneously. Four stages of egg development were found: eggs undivided and fully filled with yolk in orange egg masses; eggs with a free region of yolk visible in orange or red egg masses; embryos with slightly pigmented, crescent-shaped eyes in brown egg masses; and embryos with visible pigmented structures, enlarged eyes, segmented appendages and abdomen in brown egg masses. The mean number of external eggs carried by females in stage I was estimated to be 315,753±19,267. Three species of barnacle were observed on the exoskeleton: Poecilasma aurantia, Poecilasma crassa and Heteralepas microstoma (Cirripedia, Thoracica).     

Quantitative prediction of discrete element models on complex loading paths

The ability of discrete element models to describe quantitatively (and not only qualitatively) the constitutive behaviour of a dense sand is assessed in this paper. Two kinds of 3D discrete models are considered. Both consider spheres as elementary particles. Nevertheless, the first model implements a contact law with rolling resistance whereas the second takes into account clumps made of two spheres. The discrete models are calibrated and validated from mechanical tests performed on a dense Hostun sand with a true triaxial apparatus. The calibration is carried out from axisymmetric drained compression tests, while the validation is discussed from monotonic and cyclic stress proportional loading paths and from a circular stress path in the deviatoric stress plane. The quality of the predictions of the discrete models are evaluated by comparison with the predictions given with advanced phenomenological constitutive relations, mainly an incrementally non-linear relation. Predictions given by the discrete models are remarkable, particularly when it is put in perspective with respect to the very few number of mechanical tests required for their calibration. However, these results and conclusions were reached in enabling conditions, and some limitations of such discrete models should be kept in mind.     

Spinning in circles? A systematic review on the role of theory in social vulnerability,resilience and adaptation research

An increasing number of publications focus on social vulnerability, resilience, and adaptation (SVRA) towards natural hazards and climate change. Despite this proliferation of research, a systematic understanding of how these studies are theoretically grounded is lacking. Here, we systematically reviewed 4432 articles that address SVRA in various disciplinary fields (e.g. psychology, sociology, geography, mathematics) for various hazards, including floods, droughts, landslides, storm surges, wildfires, tsunamis, earthquakes, and volcano eruptions. We focus on the extent to which these studies explicate the frameworks, theoretical constructs or theories they rely on. Surprisingly, we found that about 90% of the reviewed studies do not explicitly refer to a theoretical underpinning. Overall, theories focusing on individuals’ SVRA were more frequently used than those focusing on systems, society, groups, and networks. Moreover, the uptake of theories varied according to the hazard investigated and field of knowledge, being more frequent in wildfire and flood studies and articles published in social science journals. Based on our analysis, we propose a reflexive handling of theories to foster more transparent, comparable, and robust empirical research on SVRA.     

小流域水分行为、生态效应及其优化调控研究方面的若干问题

把小流域水文生态研究,分解为小流域水分行为、生态效应及其优化调控研究3个方面。在分析国内外研究现状与问题的基础上,指出了其需要系统加以探讨的若干内容,认为由此可构建流域水文生态学的基本框架,进而发展流域水文生态学。     

The life cycle of contributors in collaborative online communities -the case of OpenStreetMap

Over the last two decades, online communities have become ubiquitous, with millions of people accessing collaborative project websites every day. Among them, the OpenStreetMap project (OSM) has been very successful in collecting/offering volunteered geographic information (VGI). Very different behaviours are observed among OSM participants, which translate into large differences of lifespan, contribution levels (e.g. Nielsen’s 90–9-1 rule) and attitudes towards innovations (e.g. Diffusion of innovation theory or DoIT). So far, the literature has defined phases in the life cycle of contributors only based on the nature of their contributions (e.g. role of participants and edits characteristics). Our study identifies the different phases of their life cycle from a temporal perspective and assesses how these phases relate to the volume and the frequency of the contributions from participants. Survival analyses were performed using both a complementary cumulative distribution function and a Kaplan-Meier estimator to plot survival and hazard curves. The analyses were broken down according to Nielsen and DoIT contributors’ categories to highlight potential explanatory variables. This paper shows that two contribution processes combine with three major participation stages to form six phases in contributors’ life cycle. The volume of edits provided on each active day is driven by the two contribution processes, illustrating the evolution of contributors’ motivation over time. Since contributors’ lifespan is a universal metric, our results may also apply to other collaborative online communities.     

Effectiveness of pilot carbon emissions trading systems in China

China is in the process of establishing a national emissions trading system (ETS). Evaluating the implementation effectiveness of the seven pilot ETSs in China is critical for designing this national system. This study administered a questionnaire survey to assess the behaviour of enterprises covered by the seven ETS pilots from the perspective of: the strictness of compliance measures; rules for monitoring, reporting and verification (MRV); the mitigation pressure felt by enterprises; and actual mitigation and trading activities. The results show that the pilot MRV and compliance rules have not yet been fully implemented. The main factors involved are the lack of compulsory force of the regulations and the lack of policy awareness within the affected enterprises. Most enterprises have a shortage of free allowances and thus believe that the ETSs have increased their production costs. Most enterprises have already established mitigation targets. Some of the covered enterprises are aware of their own internal emission reduction costs and most of these have used this as an important reference in trading. Many enterprises have accounted for carbon prices in their long-term investment. The proportion of enterprises that have participated in trading is fairly high; however, reluctance to sell is quite pervasive in the market, and enterprises are mostly motivated to trade simply in order to achieve compliance. Few enterprises are willing to manage their allowances in a market-oriented manner. Different free allowance allocation methods directly affect the pathways enterprises take to control emissions.

Key policy insights

• In the national ETS, the compulsory force of ETS provisions should be strengthened.

• A reasonable level of free allowance shortage should be ensured to promote emission reduction by enterprises.

• Sufficient information should be provided to guide enterprises in their allowance management to activate the market.

• To promote the implementation of mitigation technologies by enterprises, actual output-based allocation methods should be used.

• The government should use market adjustment mechanisms, such as a price floor and ceiling, to ensure that carbon prices are reasonable and stable, so as to guide long-term low carbon investment.

     

裂隙参数分析在岩体力学和水力学习性研究中的应用

岩体的力学和水力学习性主要取决于其中裂隙的发育程度。一定成因的裂隙具有一定的发育规律,这一规律既具确定性又具随机性。本文详细讨论了表示岩体裂隙发育程度特征参数的量测和分析方法,重点论述了裂隙参数分析在研究岩体渗透习性、岩体中裂隙网络计算机模拟及岩体弹性参数分析等方面的应用。     

Coupling snow accumulation and melt rate modules of monthly water balance models with the Jazim monthly water balance model

Several models for simulation of water balance processes in semi-arid mountainous basins were developed by coupling different modules of existing water balance models (WBM). Snow accumulation and snowmelt rate relationships extracted from the McCabe-Markstrom, Guo, Rao-Al Wagdany and WASMOD-M WBMs, originally developed for basins with humid climate, were coupled with the Jazim WBM, primarily developed for arid basins. Karaj Basin, central Iran, with snowy autumn–winter and dry summer periods, was selected to assess model performance. The model parameters were optimized using a genetic algorithm (GA). All coupled models performed better than the non-modified (original) WBMs in the study basin. The coupled Jazim–McCabe-Markstrom model provided the best performance in simulating low and high monthly flows. It estimated the snowmelt runoff values more accurately than other proposed coupled models because the linear relationships used in the snow module of the McCabe-Markstrom model are more compatible with snow variations in the Karaj Basin.     

Spatial behaviour of Rayleigh waves in layered half‐spaces under active surface sources

In the free state, Rayleigh waves are assumed to travel in the form of planar wavefronts. Under such an assumption, the propagation behaviour of the modes of Rayleigh waves in layered half‐spaces is only frequency dependent. The frequency behaviour, which is often termed as dispersion, is determined by the shear wave velocity profile of layered soils within the depth related to wavelength (or frequency). According to this characteristic, the shear wave velocity profile can be back‐analysed from the dispersion. The technique is widely used in the surface wave testing. However, the wavefronts of Rayleigh waves activated by the surface sources are non‐planar. The geometric discrepancy could result in Rayleigh waves manifesting distance‐dependent behaviour, which is referred to as spatial behaviour in this paper. Conventional analysis ignoring this spatial behaviour could introduce unexpected errors. In order to take the effects of sources on the propagation behaviour into account, a new mathematical model is established for Rayleigh waves in layered elastic media under vertical disc‐like surface sources using the thin‐layer method. The spatial behaviour of the activated modes and the apparent phase velocity, which is the propagation velocity of Rayleigh waves superposed by the multiple modes, are then analysed. Aspects of the spatial behaviour investigated in this paper include the equilibrium path, the particle orbit, and the geometric attenuation of the activated Rayleigh waves. The results presented in this paper can provide some guidelines for developing new inverse mathematical models and algorithms.