Characterization of Graphs With Failed Skew Zero Forcing Number of 1

Given a graph $G$, the zero forcing number of $G$, $Z(G)$, is the smallest cardinality of any set $S$ of vertices on which repeated applications of the forcing rule results in all vertices being in $S$. The forcing rule is: if a vertex $v$ is in $S$, and exactly one neighbor $u$ of $v$ is not in $S$, then $u$ is added to $S$ in the next iteration. Hence the failed zero forcing number of a graph was defined to be the size of the largest set of vertices which fails to force all vertices in the graph. A similar property called skew zero forcing was defined so that if there is exactly one neighbor $u$ of $v$ is not in $S$, then $u$ is added to $S$ in the next iteration. The difference is that vertices that are not in $S$ can force other vertices. This leads to the failed skew zero forcing number of a graph, which is denoted by $F^{-}(G)$. In this paper we provide a complete characterization of all graphs with $F^{-}(G)=1$. Fetcie, Jacob, and Saavedra showed that the only graphs with a failed zero forcing number of $1$ are either: the union of two isolated vertices; $P_3$; $K_3$; or $K_4$. In this paper we provide a surprising result: changing the forcing rule to a skew-forcing rule results in an infinite number of graphs with $F^{-}(G)=1$.Comment: 8 pages, this research was supported by the National Science Foundation Research forUndergraduates Award 195018

Seascape Connectivity of Gulf Sturgeon \u3ci\u3eAcipenser oxyrinchus desotoi\u3c/i\u3e Population Units Across the Northern Gulf of Mexico

Critical habitat was designated in 2003 for federally threatened anadromous Gulf sturgeon to aid in population recovery. This study examined overwintering Gulf sturgeon spatial use and movement through critical habitat monitored by the Ship Island acoustic array from 2011 to 2015. Previous studies observed western population Gulf sturgeon (Pearl and Pascagoula rivers) overwintering near the ends and within the passes of the barrier islands of the Mississippi Sound, USA. Recent telemetry studies detected eastern population fish (Escambia, Blackwater, Yellow, and Choctawhatchee rivers) overwintering as far west as Mobile Bay, Alabama; however, this study is the first to observe eastern population fish overwintering in western population critical habitat associated with the Ship Island array. Use of overwintering habitat was compared using mean active days detected and rate of travel to and from the array. There was no significant difference in mean active days of population units on the array; however, travel rate to the array from natal drainages was significantly different, with eastern population individuals traveling at a faster rate compared to western population individuals. Post hoc tests indicated that individuals from the Blackwater River had a significantly higher travel rate compared to Pascagoula River individuals. We documented large-scale seascape connectivity among population units of Gulf sturgeon across the northern Gulf of Mexico. Although large-scale seascape connectivity promotes mixing among population units and an exchange of marine nutrients into riverine environments, large-scale migration poses an issue for endangered species such as Gulf sturgeon, as there is greater risk of bycatch mortality and size-specific predation

Reactivity of Hydroxymethylated Resorcinol Coupling Agent as it Affects Durability of Epoxy Bonds to Douglas-fir

Epoxy adhesives develop strong bonds to wood, but they lack the structural durability to withstand the severe stresses from repeated water soaking and drying. Research at the Forest Products Laboratory led to a discovery that hydroxymethylated resorcinol (HMR) physicochemically couples to both epoxy adhesive and lignocellulosics of wood to produce bonds that are extraordinarily resistant to dclamination. The HMR coupling agent is quite reactive at room temperatures; therefore, the length of its reaction time, or the time between preparing the solution and applying it to the wood surface, strongly influences the durability of adhesion. The experiments in this study defined the optimum range of reaction time when adhesion is maximum for epoxy bonds to HMR-primed Douglas-fir. Heats of reaction (by differential scanning calorimetry), molecular-size distribution (by gel permeation chro-matography), and chemical structures of HMR (by carbon-13 nuclear magnetic resonance spectros-copy) are described for this range of optimum reaction times

Swelling of acetylated wood in organic liquids

To investigate the affinity of acetylated wood for organic liquids, Yezo spruce wood specimens were acetylated with acetic anhydride, and their swelling in various liquids were compared to those of untreated specimens. The acetylated wood was rapidly and remarkably swollen in aprotic organic liquids such as benzene and toluene in which the untreated wood was swollen only slightly and/or very slowly. On the other hand, the swelling of wood in water, ethylene glycol and alcohols remained unchanged or decreased by the acetylation. Consequently the maximum volume of wood swollen in organic liquids was always larger than that in water. The effect of acetylation on the maximum swollen volume of wood was greater in liquids having smaller solubility parameters. The easier penetration of aprotic organic liquids into the acetylated wood was considered to be due to the scission of hydrogen bonds among the amorphous wood constituents by the substitution of hydroxyl groups with hydrophobic acetyl groups.Comment: to be published in J Wood Science (Japanese wood research society

Tissue Engineering Strategies for Myocardial Regeneration: Acellular Versus Cellular Scaffolds?

Heart disease remains one of the leading causes of death in industrialized nations with myocardial infarction (MI) contributing to at least one fifth of the reported deaths. The hypoxic environment eventually leads to cellular death and scar tissue formation. The scar tissue that forms is not mechanically functional and often leads to myocardial remodeling and eventual heart failure. Tissue engineering and regenerative medicine principles provide an alternative approach to restoring myocardial function by designing constructs that will restore the mechanical function of the heart. In this review, we will describe the cellular events that take place after an MI and describe current treatments. We will also describe how biomaterials, alone or in combination with a cellular component, have been used to engineer suitable myocardium replacement constructs and how new advanced culture systems will be required to achieve clinical success

Engaging zoo visitors at chimpanzee (Pan troglodytes) exhibits promotes positive attitudes toward chimpanzees and conservation

Understanding how visitor engagement with interpretation impacts on their attitudes to conservation is necessary to develop effective zoo-based conservation education. We examined whether facilitating an emotional connection between a visitor and an individual chimpanzee (Pan troglodytes) was more successful at enhancing attitudes than standard zoo interpretation. Attitudes were assessed post visit using a 12-item questionnaire on predisposition toward nature, attitudes to chimpanzees, and conservation. Visitors at two chimpanzee exhibits were allocated to an emotion enhancement condition (n = 227) or a control condition (n = 203). At one exhibit, visitors were also allocated to an interactive task (location) without emotional enhancement (n = 69). Participants were also recruited to an online control condition (n = 216). Principal component analyses identified two components labeled as Naturalistic, which refers to interest and affection for wildlife and nature, and Humanistic, which refers to interest and affection for individual animals or species with anthropomorphic characteristics. At one exhibit, both Naturalistic and Humanistic attitudes were significantly more positive following the emotion enhancement condition than for the control condition. At the other exhibit, Naturalistic and Humanistic components did not differ between conditions, and there was no overall difference between online and on-site conditions. While emotional enhancement may be effective in promoting pro-conservation attitudes, this is dependent on contextual factors (e.g., exhibit design and interpretation). Attitudes were also influenced by stable visitor characteristics (pet ownership and zoo membership) and are therefore likely to prove difficult to change, at least during a single zoo visit. Visitor and animal characteristics, and the interpretation of the exhibit all shape the visitor experience; understanding these interactions is important in facilitating effective zoo conservation education

Exploration of potential triggers for self-directed behaviours and regurgitation and reingestion in zoo-housed chimpanzees

The unique challenges faced by animals living in zoos can lead to the production of anxiety-related behaviours. In this study we aimed to understand what specific factors may cause chimpanzees to display these behaviours. In non-human primates, displacement behaviours, such as self-scratching and yawning, are considered markers of anxiety and stress, and Regurgitation and Reingestion (R/R) is considered an abnormal behaviour with negative consequences for physical health. We examined the possible triggers of R/R, scratching, and yawning in a group of zoo-housed chimpanzees and followed this up with an analysis of long-term data to examine further aspects of R/R behaviour. In the first study we conducted focal observations on 18 adult chimpanzees at Edinburgh Zoo, UK, in addition to all occurrence sampling of visitors using flash photography, screaming and banging on the glass in the exhibit. 158 h of data were analysed and Generalised Linear Mixed Models revealed that yawning was significantly more likely if there was a long period of time since the last feed and when there were moderate numbers of visitors in the zoo. There were trends that yawning was more likely to occur if children screamed and that scratching was more likely to occur if visitors used flash photography. R/R occurred most often within 40 min of a feed, but was not affected by the inter-feed interval preceding that feed, positive or negative social interactions, or visitor numbers or behaviour. As there was no obvious daily trigger for R/R, an analysis of long-term data (2009 to 2015) was conducted to investigate if social or dietary factors affected rates of R/R over a larger timescale. It was found that R/R rates in the months before a significant diet change were not different from R/R rates in the months after, but it was found that R/R rates decreased over the five-year period. Lastly, we found no evidence that the introduction of individuals engaging in R/R lead to resident chimpanzees habitually adopting the behaviour, despite considerable opportunities to observe it. These findings have implications for welfare interventions aimed to reduce R/R and/or anxiety behaviours in captive populations and for the translocation of individuals that are known to engage in R/R between groups.Peer reviewe

Dopant Spatial Distributions: Sample Independent Response Function And Maximum Entropy Reconstruction

We demonstrate the use of maximum entropy based deconvolution to reconstruct boron spatial distribution from the secondary ion mass spectrometry (SIMS) depth profiles on a system of variously spaced boron $\delta$-layers grown in silicon. Sample independent response functions are obtained using a new method which reduces the danger of incorporating real sample behaviour in the response. Although the original profiles of different primary ion energies appear quite differently, the reconstructed distributions agree well with each other. The depth resolution in the reconstructed data is increased significantly and segregation of boron at the near surface side of the $\delta$-layers is clearly shown.Comment: 5 two-columne pages, 3 postscript figures, to appear in Phys. Rev. B1