Three Algorithms for a Class of Multidimensional Assignment Problems

The assignment problem of matching the elements of two sets at some cost or to some benefit is well known and can be solved in polynomial time. However, many applications, particularly those in remote sensing and computer vision, require matching elements from more than two sets at some cost. Such problems are called multidimensional assignment problems and are known to be NP-hard. For time-critical applications and nontrivial multidimensional assignment problems, fast near-optimal algorithms are the only alternative. This paper compares three such algorithms: greedy, limited branch and bound, and Lagrangian relaxation

Global patterns in seagrass herbivory: Why, despite existing evidence, there are solid arguments in favor of latitudinal gradients in seagrass herbivory

© 2020, Coastal and Estuarine Research Federation. The ecological paradigm that biological interactions are more intense in the tropics than in temperate or polar regions has existed since the mid-twentieth century, but several recent meta-analyses have provided scant evidence for latitudinal gradients in the intensity of herbivory. This contradictory evidence led us to carefully review the data and results of several of those papers that failed to find latitudinal gradients in rates of seagrass herbivory. To re-evaluate the arguments around the presence or absence of latitudinal gradients in herbivory in seagrass, we began by expanding the selection criteria to include more studies to compare the published latitudinal range of seagrass occurrences with the latitudes in which seagrass herbivory has been studied. We also compared the latitudinal range of known seagrass herbivores with the distribution of studies on seagrass herbivory. Finally, we investigated studies that provided seasonal data on net primary production and standing stock of seagrasses, which allowed an assessment of the relative amounts of production that could enter the seagrass grazing food web among latitudes and climatic regimes. Consistent with recent meta-analyses, we found little latitudinal effect on grazing rates. However, we argue that the following factors are likely to confound these findings and potentially mask latitudinal trends in seagrass herbivory: (1) the paucity of data available to test latitudinal trends in grazing rates at high latitudes; (2) the mismatch between the geographic distribution of important grazers and studies on seagrass herbivory; (3) the paucity of experimental studies from areas with little or no herbivory because few researchers would initiate a study on something not observed to be occurring; (4) the high level of seasonality in seagrass production in high latitudes, where seagrass production is very low or nonexistent in winter months; (5) the fact that temperate areas with Mediterranean climates behave very differently than temperate areas at similar latitudes with much greater seasonality, thereby making latitude a much less informative independent variable than annual range in temperature; and (6) anthropogenic disturbances, including the overharvesting to functional extinction of large seagrass herbivores in both temperate and tropical regions. Thus, while we currently cannot discount the lack of a latitudinal gradient in grazing intensity, we argue that the intensity of grazing is likely to be greater in the tropics than high-latitude regions where the carrying capacity of seagrass meadows is far less stable. Either way, there are clear gaps in our knowledge and ability to evaluate the role of grazing in seagrass ecosystems and inform future efforts to conserve and restore these extraordinarily valuable ecosystems

Irregular silviculture and stand structural effects on the plant community in an ancient semi-natural woodland

Plants associated with traditional forms of coppice management are affected by changes in, or cessation of, stand management which produce differences in structure, usually in the direction of high forest. The habitat structure, ground flora richness, and composition of an ancient woodland in southern England were compared across three distinct management treatments: traditional Coppice (the cyclical cutting of underwood on rotations), Limited Intervention (representing the effective cessation of management), and Irregular High Forest silviculture (a form of continuous cover forestry using single and small group selective tree harvesting). Coppice and Irregular silviculture showed a more complex woody stand structure whereas Limited Intervention was strongly correlated with closed-canopy, single-storied structures and no developing understorey. Increased bramble Rubus fruticosus cover was strongly associated with Irregular silviculture, bare ground mostly with the limited intervention closed-canopy stands. Distinct plant-habitat associations were identified across stand management types with the greatest differences between Limited Intervention and the two active interventions. Overall vascular plant species and Coppice group species were lowest in Limited Intervention stands. Using ancient woodland indicator and Coppice plant species and groups, we found a similar community pattern between Coppice and Irregular silviculture. More ancient woodland species were accommodated within the comparatively heterogenous woodland habitat associated with active silvicultural interventions of Coppice and Irregular High Forest management. The study indicates that the introduction of Irregular silviculture as practiced here can conserve most ancient woodland and Coppice plants associated with traditional coppicing, a practice which has declined significantly in the UK since the late 19th Century

Marine Biodiversity in the Australian Region

The entire Australian marine jurisdictional area, including offshore and sub-Antarctic islands, is considered in this paper. Most records, however, come from the Exclusive Economic Zone (EEZ) around the continent of Australia itself. The counts of species have been obtained from four primary databases (the Australian Faunal Directory, Codes for Australian Aquatic Biota, Online Zoological Collections of Australian Museums, and the Australian node of the Ocean Biogeographic Information System), but even these are an underestimate of described species. In addition, some partially completed databases for particular taxonomic groups, and specialized databases (for introduced and threatened species) have been used. Experts also provided estimates of the number of known species not yet in the major databases. For only some groups could we obtain an (expert opinion) estimate of undiscovered species. The databases provide patchy information about endemism, levels of threat, and introductions. We conclude that there are about 33,000 marine species (mainly animals) in the major databases, of which 130 are introduced, 58 listed as threatened and an unknown percentage endemic. An estimated 17,000 more named species are either known from the Australian EEZ but not in the present databases, or potentially occur there. It is crudely estimated that there may be as many as 250,000 species (known and yet to be discovered) in the Australian EEZ. For 17 higher taxa, there is sufficient detail for subdivision by Large Marine Domains, for comparison with other National and Regional Implementation Committees of the Census of Marine Life. Taxonomic expertise in Australia is unevenly distributed across taxa, and declining. Comments are given briefly on biodiversity management measures in Australia, including but not limited to marine protected areas

Benchmarking global biodiversity of decapod crustaceans (Crustacea: Decapoda)

A new assessment of the global biodiversity of decapod Crustacea (to 31 December 2022) records 17,229 species in 2,550 genera and 203 families. These figures are derived from a well-curated dataset maintained on the online platform DecaNet, a subsidiary of the World Register of Marine Species (WoRMS). Distinct phases are recognised in the discovery process (as measured by species descriptions) corresponding to major historical and geopolitical time periods, with the current rate of species descriptions being more than three times higher than in the Victorian age of global exploration. Future trends are briefly explored, and it is recognised that a large number of species remain to be discovered and described

Specific inhibition of p25/Cdk5 activity by the Cdk5 inhibitory peptide reduces neurodegeneration in vivo

The aberrant hyperactivation of Cyclin-dependent kinase 5 (Cdk5), by the production of its truncated activator p25, results in the formation of hyperphosphorylated tau, neuroinflammation, amyloid deposition, and neuronal death in vitro and in vivo. Mechanistically, this occurs as a result of a neurotoxic insult that invokes the intracellular elevation of calcium to activate calpain, which cleaves the Cdk5 activator p35 into p25. It has been shown previously that the p25 transgenic mouse as a model to investigate the mechanistic implications of p25 production in the brain, which recapitulates deregulated Cdk5-mediated neuropathological changes, such as hyperphosphorylated tau and neuronal death. To date, strategies to inhibit Cdk5 activity have not been successful in targeting selectively aberrant activity without affecting normal Cdk5 activity. Here we show that the selective inhibition of p25/Cdk5 hyperactivation in vivo, through overexpression of the Cdk5 inhibitory peptide (CIP), rescues against the neurodegenerative pathologies caused by p25/Cdk5 hyperactivation without affecting normal neurodevelopment afforded by normal p35/Cdk5 activity. Tau and amyloid pathologies as well as neuroinflammation are significantly reduced in the CIP-p25 tetra transgenic mice, whereas brain atrophy and subsequent cognitive decline are reversed in these mice. The findings reported here represent an important breakthrough in elucidating approaches to selectively inhibit the p25/Cdk5 hyperactivation as a potential therapeutic target to reduce neurodegeneration

Hand sanitisers for reducing illness absences in primary school children in New Zealand: a cluster randomised controlled trial study protocol

<p>Abstract</p> <p>Background</p> <p>New Zealand has relatively high rates of morbidity and mortality from infectious disease compared with other OECD countries, with infectious disease being more prevalent in children compared with others in the population. Consequences of infectious disease in children may have significant economic and social impact beyond the direct effects of the disease on the health of the child; including absence from school, transmission of infectious disease to other pupils, staff, and family members, and time off work for parents/guardians. Reduction of the transmission of infectious disease between children at schools could be an effective way of reducing the community incidence of infectious disease. Alcohol based no-rinse hand sanitisers provide an alternative hand cleaning technology, for which there is some evidence that they may be effective in achieving this. However, very few studies have investigated the effectiveness of hand sanitisers, and importantly, the potential wider economic implications of this intervention have not been established.</p> <p>Aims</p> <p>The primary objective of this trial is to establish if the provision of hand sanitisers in primary schools in the South Island of New Zealand, in addition to an education session on hand hygiene, reduces the incidence rate of absence episodes due to illness in children. In addition, the trial will establish the cost-effectiveness and conduct a cost-benefit analysis of the intervention in this setting.</p> <p>Methods/Design</p> <p>A cluster randomised controlled trial will be undertaken to establish the effectiveness and cost-effectiveness of hand sanitisers. Sixty-eight primary schools will be recruited from three regions in the South Island of New Zealand. The schools will be randomised, within region, to receive hand sanitisers and an education session on hand hygiene, or an education session on hand hygiene alone. Fifty pupils from each school in years 1 to 6 (generally aged from 5 to 11 years) will be randomly selected for detailed follow-up about their illness absences, providing a total of 3400 pupils. In addition, absence information will be collected on all children from the school rolls. Investigators not involved in the running of the trial, outcome assessors, and the statistician will be blinded to the group allocation until the analysis is completed.</p> <p>Trial registration</p> <p>ACTRN12609000478213</p