Is the tetraneutron a bound dineutron-dineutron molecule?

In light of a new experiment which claims a positive identification, we discuss the possible existence of the tetraneutron. We explore a novel model based on a dineutron-dineutron molecule. We show that this model is not able to explain the tetraneutron as a bound state, in agreement with other theoretical models already discussed in the literature.Comment: 9 pages, 3 figures, J. Phys. G, in pres

The detection of neutron clusters

A new approach to the production and detection of bound neutron clusters is presented. The technique is based on the breakup of beams of very neutron-rich nuclei and the subsequent detection of the recoiling proton in a liquid scintillator. The method has been tested in the breakup of 11Li, 14Be and 15B beams by a C target. Some 6 events were observed that exhibit the characteristics of a multineutron cluster liberated in the breakup of 14Be, most probably in the channel 10Be+4n. The various backgrounds that may mimic such a signal are discussed in detail.Comment: 11 pages, 12 figures, LPCC 01-1

An ecological future for weed science to sustain crop production and the environment. A review

Sustainable strategies for managing weeds are critical to meeting agriculture's potential to feed the world's population while conserving the ecosystems and biodiversity on which we depend. The dominant paradigm of weed management in developed countries is currently founded on the two principal tools of herbicides and tillage to remove weeds. However, evidence of negative environmental impacts from both tools is growing, and herbicide resistance is increasingly prevalent. These challenges emerge from a lack of attention to how weeds interact with and are regulated by the agroecosystem as a whole. Novel technological tools proposed for weed control, such as new herbicides, gene editing, and seed destructors, do not address these systemic challenges and thus are unlikely to provide truly sustainable solutions. Combining multiple tools and techniques in an Integrated Weed Management strategy is a step forward, but many integrated strategies still remain overly reliant on too few tools. In contrast, advances in weed ecology are revealing a wealth of options to manage weedsat the agroecosystem levelthat, rather than aiming to eradicate weeds, act to regulate populations to limit their negative impacts while conserving diversity. Here, we review the current state of knowledge in weed ecology and identify how this can be translated into practical weed management. The major points are the following: (1) the diversity and type of crops, management actions and limiting resources can be manipulated to limit weed competitiveness while promoting weed diversity; (2) in contrast to technological tools, ecological approaches to weed management tend to be synergistic with other agroecosystem functions; and (3) there are many existing practices compatible with this approach that could be integrated into current systems, alongside new options to explore. Overall, this review demonstrates that integrating systems-level ecological thinking into agronomic decision-making offers the best route to achieving sustainable weed management

Neutron sources: Present practice and future potential

The present capability and future potential of accelerator-based monoenergetic and white neutron sources are outlined in the context of fundamental and applied neutron-nuclear research. The neutron energy range extends from thermal to 500 MeV, and the time domain from steady-state to pico-second pulsed sources. Accelerator technology is summarized, including the production of intense light-ion, heavy-ion and electron beams. Target capabilities are discussed with attention to neutron-producing efficiency and power-handling capabilities. The status of underlying neutron-producing reactions is summarized. The present and future use of neutron sources in: fundamental neutron-nuclear research, nuclear data acquisition, materials damage studies, engineering tests, and biomedical applications are discussed. Emphasis is given to current status, near-term advances well within current technology, and to long-range projections. 90 refs., 4 figs

Plant species diversity in alien black locust stands: A paired comparison with native stands across a north-Mediterranean range expansion

Black locust (Robinia pseudoacacia L.) is a widespread alien tree species commonly thought to influence plant assemblages. The aim of this study was to compare the plant diversity between black locust and native recent secondary stands within the European Mediterranean Mountains environmental zone. Spontaneous reforestation was detected by comparing historical aerial photographs and the most recent images. Distributed throughout a 2700 km2 hilly and piedmont area, 32 black locust and 32 paired native stands were selected and all vascular plant species were surveyed in a 100 m2 area. Analyses of the \u3b1 and \u3b2-diversity were performed separately for six identified plant groups. Despite a clear difference in the tree diversity between the black locust and native recent secondary stands and a homogenisation of the tree layer by the black locust stands, we found only inconsistent hints for homogenisation of the ground-layer vegetation by the black locust stands. There is no evidence to suggest that the presence of black locust in recent secondary stands plays a major role in shaping the diversity of the understory plant groups compared to native stands

Appendix D. Model documentation of carbon sequestration in fine roots with the mean annual temperature included.

Model documentation of carbon sequestration in fine roots with the mean annual temperature included

Appendix H. Model documentation of carbon sequestration in aboveground woody biomass without climate and flooding parameters.

Model documentation of carbon sequestration in aboveground woody biomass without climate and flooding parameters

Appendix K. Means and standard errors (SE) of selected climate, stream flow, hydrological, spatial, and forest stand parameters used for modeling C sequestration in litterfall, fine root, and aboveground biomass (with RNW = Water level duration exceeding ca. 343 days/year; MW = Averaged water level; HSW = Water level duration exceeding ca. 3.6 days/year; approximately bankful discharge).

Means and standard errors (SE) of selected climate, stream flow, hydrological, spatial, and forest stand parameters used for modeling C sequestration in litterfall, fine root, and aboveground biomass (with RNW = Water level duration exceeding ca. 343 days/year; MW = Averaged water level; HSW = Water level duration exceeding ca. 3.6 days/year; approximately bankful discharge)

Appendix C. Model documentation of carbon sequestration in fine roots without climate and flooding parameters.

Model documentation of carbon sequestration in fine roots without climate and flooding parameters