73 research outputs found
The -visibility Localization Game
We study a variant of the Localization game in which the cops have limited
visibility, along with the corresponding optimization parameter, the
-visibility localization number , where is a non-negative
integer. We give bounds on -visibility localization numbers related to
domination, maximum degree, and isoperimetric inequalities. For all , we
give a family of trees with unbounded values. Extending results known
for the localization number, we show that for , every tree contains a
subdivision with . For many , we give the exact value of
for the Cartesian grid graphs, with the remaining cases
being one of two values as long as is sufficiently large. These examples
also illustrate that for all distinct choices of and
$j.
Distance-Restricted Firefighting on Finite Graphs
In the classic version of the game of firefighter, on the first turn a fire
breaks out on a vertex in a graph and then firefighters protect
vertices. On each subsequent turn, the fire spreads to the collective unburnt
neighbourhood of all the burning vertices and the firefighters again protect
vertices. Once a vertex has been burnt or protected it remains that way for
the rest of the game. We previously introduced the concept of
where the firefighters' movement is
restricted so they can only move up to some fixed distance and they may or
may not be permitted to move through burning vertices. In this paper we
establish the NP-Completeness of the distance-restricted versions of the
problem and present an integer program for
solving these problems. In the penultimate section we also discuss some
interesting properties of the function
Siege of British Forces in Newport County by Colonial and French in August 1778
Funded by a grant from the National Park Service American Battlefield Protection Program, this study delves into the technical, often forgotten, aspects of the Siege of Newport - a Revolutionary War engagement that took place in Middletown, RI in August 1778. It pairs the historical record with scientific analysis of the artillery, fortifications, geography and unforeseen circumstances that impacted the Siege. While much of the original earthen defense-works are now gone, there are a small number of sites that still exist. This study also covers what sites remain, their condition and thoughts on how to preserve and commemorate them.https://digitalcommons.salve.edu/fac_staff_ebooks/1003/thumbnail.jp
Marine mammal hotspots across the circumpolar Arctic
Aim: Identify hotspots and areas of high species richness for Arctic marine mammals. Location: Circumpolar Arctic. Methods: A total of 2115 biologging devices were deployed on marine mammals from 13 species in the Arctic from 2005 to 2019. Getis-Ord Gi* hotspots were calculated based on the number of individuals in grid cells for each species and for phyloge-netic groups (nine pinnipeds, three cetaceans, all species) and areas with high spe-cies richness were identified for summer (Jun-Nov), winter (Dec-May) and the entire year. Seasonal habitat differences among speciesâ hotspots were investigated using Principal Component Analysis. Results: Hotspots and areas with high species richness occurred within the Arctic continental-shelf seas and within the marginal ice zone, particularly in the âArctic gatewaysâ of the north Atlantic and Pacific oceans. Summer hotspots were generally found further north than winter hotspots, but there were exceptions to this pattern, including bowhead whales in the Greenland-Barents Seas and species with coastal distributions in Svalbard, Norway and East Greenland. Areas with high species rich-ness generally overlapped high-density hotspots. Large regional and seasonal dif-ferences in habitat features of hotspots were found among species but also within species from different regions. Gap analysis (discrepancy between hotspots and IUCN ranges) identified species and regions where more research is required. Main conclusions: This study identified important areas (and habitat types) for Arctic marine mammals using available biotelemetry data. The results herein serve as a benchmark to measure future distributional shifts. Expanded monitoring and teleme-try studies are needed on Arctic species to understand the impacts of climate change and concomitant ecosystem changes (synergistic effects of multiple stressors). While efforts should be made to fill knowledge gaps, including regional gaps and more com-plete sex and age coverage, hotspots identified herein can inform management ef-forts to mitigate the impacts of human activities and ecological changes, including creation of protected areas
Say on Pay: A wolf in sheepâs clothing?
This paper debates whether Say on Pay can fix executive pay. We argue that Say on Pay benefits executive pay when shareholdersâ voice offsets CEO power and mitigates directorsâ information deficiencies. We admonish however that Say on Pay may raise novel problems. The pay resulting from Say on Pay can harm stakeholders whose interests differ from those of shareholders influential in pay- setting. Moreover, boards may resist shareholdersâ intervention in pay-setting and, accordingly, manage compensation disclosures to ensure a passing shareholder vote. Consequently, Say on Pay may not only fail to remedy suboptimal pay but also legitimize it
A variation on the firefighter problem on graphs
In the classic version of the game of Firefighter, on the first turn a fire breaks out on a
vertex in a graph G and then k firefighters protect k vertices. On each subsequent turn,
the fire spreads to the collective unburnt neighbourhood of all the burning vertices and the
firefighters again protect k vertices. Once a vertex has been burnt or protected it remains
that way for the rest of the game. A common objective with respect to some infinite graph
G is to determine how many firefighters are necessary to stop the fire from spreading after
a finite number of turns, commonly referred to as containing the fire. We introduce the
concept of distance-restricted firefighting where the firefightersâ movement is restricted so
they can only move up to some fixed distance d per turn rather than being able to move
without restriction. We establish some general properties of this new game in contrast to
properties of the original game, and we investigate specific cases of the distance-restricted
game on the infinite strong, hexagonal, and square grids. We conjecture that two firefighters
are insufficient on the square grid when d =2, and we pose some questions about how many
firefighters are required in general when d = 1
Summer distribution and habitat preference of beluga whale social groups in the Eastern Beaufort Sea
In social animals, group composition can cause variations in individual needs that can influence responses to habitat trade-offs, such as predator exposure or foraging opportunities. The Eastern Beaufort Sea beluga whales (Delphinapterus leucas (Pallas, 1776)) form different group types and cover multiple habitat types in summer. This study compares the habitat preference of three beluga social group types: (1) individual belugas, (2) groups of adults, and (3) groups with at least one calf. Observations were collected during aerial surveys in July and August 2019. For each month, beluga distribution was analyzed with hierarchical generalized additive models, as a function of group type and four covariates: sea surface temperature, bathymetry, slope, and distance to the coastline. Group type, water temperature, and bathymetric features best explained beluga distribution. In July, groups of adults preferred the continental shelf, whereas individual belugas and groups with calves preferred the continental slope. In August, groups of adults and groups with calves were found in Amundsen Gulf at similar depths. For both months, individual belugas associated more with deeper and colder areas. The preferences often corresponded to previously published distributions of the beluga's main prey species, suggesting that foraging opportunities and size-related energy requirements strongly influence habitat use
Phenotypic characterization of acoustically enriched extracellular vesicles from pathogen-activated platelets
Extracellular vesicles (EVs) are derived from the membrane of platelets and released in the circulation upon activation or injury. Analogous to the parent cell, platelet derived EVs play an important role in hemostasis and immune responses by transfer of bioactive cargo from the parent cells. Platelet activation and release of EVs increases in several pathological inflammatory diseases, such as sepsis. We have previously reported that the M1 protein released from the bacterial pathogen Streptococcus pyogenes directly mediates platelet activation. In this study, EVs were isolated from these pathogen-activated platelets using acoustic trapping and their inflammation phenotype was characterized using quantitative mass spectrometry-based proteomics and cell-based models of inflammation. We determined that M1 protein mediated release of platelet derived EVs that contained the M1 protein. The isolated EVs derived from pathogen-activated platelets contained a similar protein cargo to those from physiologically activated platelets (thrombin), and included platelet membrane proteins, granule proteins and cytoskeletal proteins, coagulation factors and immune mediators. Immunomodulatory cargo, complement proteins and IgG3, were significantly enriched in EVs isolated from M1 protein-stimulated platelets. Acoustically enriched EVs were functionally intact and exhibited proinflammatory effects on addition to blood, including platelet-neutrophil complex formation, neutrophil activation, and cytokine release. Collectively, our findings reveal novel aspects of pathogen-mediated platelet activation during invasive streptococcal infection
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