When cracks look different

In this work, by means of numerical experiments based on Los Alamos National Laboratory’s combined finite discrete element method (FDEM) software package MUNROU, it is demonstrated that fracture patterns do not only depend on the solid properties, but that the presence of a fluid medium plays a key role in driving both the dynamic fracture propagation and stress state in solid. The “dry” and “wet” fracture patterns obtained in this work look very different, thus emphasizing the critical importance of capturing all of the “first principle physics” involved in order to modelall the phases of a given fracturing medium

Tumour necrosis factor-alpha (TNFα) stimulates the growth of human bone marrow stromal cells

This study reports that TNF-α is a potent mitogen for human bone marrow sternal cells in vitro (assessed by [3H]-thymidine incorporation into DNA and cell counts). In contrast, cytokines such as IL-1α, IL-1β, IL-2, IL-3, IL-4, IL-6, LIF, SCF, M-CSF, G-CSF and GM-CSF had no effect. The effect of TNF-α on the growth of human bone marrow stromal cells could be of importance during inflammatory processes which take place in the marrow, for example marrow fibrosis

From particulates toscience of discontinua: generalization of particle simulation methods

In this work, we demonstrate that the rapid developments of methods of discontinua, when coupled with virtual experimentation and complementary discontinua based experimental and theoretical methods, are resulting in a significant paradigm shift from continuum-based analyses to either discontinuum and/or combined continuum discontinumbased approaches. Applications of these new approaches are so diverse (covering topics from traditional mineral processing to applications such as medical research, nano-science, social sciences, astrophysics, etc.) that what started as research on particulate media is rapidly transforming into the science of discontinua. In this paper, this trend is clearly demonstrated through a comparative study of both the fundamental developments in the core simulation technologies (together with synergies between different simulation tools) and their diverse fields of applications

Preserving significant historical structures with the help of computational mechanics of discontinua

Architectural and engineering geniuses of ancient times have left to the world an important heritage of stone, masonry and other structures ranging from temples, churches, mosques, pyramids to aqueducts, palaces, and dams. Preserving these for future generations is one of the more important challenges facing modern civilization. In some places vibrations from traffic can be a cause of gradual damage, which if not counteracted could result in eventual catastrophic collapse. More often than not, it is earthquakes that pose such a threat that catastrophic failure could occur. Other factors or combination of factors can also cause catastrophic distress to a structure (impacts, blasts, fire, lightening, etc.). Modern engineering design practices usually consider the so called ultimate limit states for a structure as a whole. By using the theory of probability for design parameters such as loads and material properties, one can arrive at the probability of a catastrophic failure of a structure given a particular event. The problem with applying these to significant historical structures is that the computational tools available are at times somewhat limited for ancient structure analyses purposes simply because of the specific and innovative ways the structures were built. In this paper, using the Los Alamos MUNROU package it is demonstrated that the combined finite discrete element method (FDEM) has some unique capabilities in modeling the ultimate limit state ofhistorical buildings;each individual stone blocks or stone anchors could potentially be captured with accurate representation of frictional energy dissipation under transient dynamic loads. Our work here focuses on an initial cursory analysis of the potential earthquake threat posed to one of the most famous historical structures, the Santa Maria Del Fiore Dome in Florence

Community based aquaculture in the western Indian Ocean: Challenges and opportunities for developing sustainable coastal livelihoods

The small-fisheries social-ecological system in the western Indian Ocean (WIO) represents a typical social-ecological trap setting where very poor natural resources dependent coastal communities face local and global threats and engage in unsustainable practices of exploiting limited resources. Community-based aquaculture (CBA) has been implemented as an important alternative or supplementary income generating activity for minimizing the overdependence on marine natural resources and promoting biodiversity conservation. Despite its proliferation throughout the WIO region in recent decades, little is known about the degree to which CBA activities have contributed to achieving the objectives of breaking the cycle of poverty and environmental degradation and promoting community development and biodiversity conservation. In order to improve understanding of common challenges and to generate recommendations for best practice, we assessed the most common CBA activities practiced in the region through literature review and workshop discussion involving practitioners and key stakeholders. Findings indicated that despite favorable environmental conditions for various CBA practices, the sector remains underdeveloped, with few activities delivering the intended benefits for coastal livelihoods or conservation. Constraints included a shortage of seed and feed supplies, low investment, limited technical capacity and skills, insufficient political support, and lack of a clear strategy for aquaculture development. These are compounded by a lack of engagement of local stakeholders, with decision making often dominated by donors, development agencies, and private sector partners. Many of the region’s CBA projects are designed along unrealistically short time frames, driven by donors rather than entrepreneurs, and so are unable to achieve financial sustainability, which limits the opportunity for capacity building and longer-term development. There is little or no monitoring on ecological and socioeconomic impacts. Except for a few isolated cases, links between CBA and marine conservation outcomes have rarely been demonstrated. Realizing the potential of CBA in contributing toward food security in the WIO will necessitate concerted investment and capacity strengthening to overcome these systemic challenges in the sector. Lessons herein offer managers, scientists, and policy advisors guidance on addressing the challenges faced in building strategic development initiatives around aquaculture in developing countries