Thomassen's Choosability Argument Revisited

Thomassen (1994) proved that every planar graph is 5-choosable. This result was generalised by {\v{S}}krekovski (1998) and He et al. (2008), who proved that every $K_5$-minor-free graph is 5-choosable. Both proofs rely on the characterisation of $K_5$-minor-free graphs due to Wagner (1937). This paper proves the same result without using Wagner's structure theorem or even planar embeddings. Given that there is no structure theorem for graphs with no $K_6$-minor, we argue that this proof suggests a possible approach for attacking the Hadwiger Conjecture

Adding Texture and Relief to Seattle’s New Seawall, an Application of Ecological Engineering

The aftermath of the 2001 Nisqually earthquake revealed that Seattle’s seawall was decaying and in need of replacement. The resulting seawall replacement project presented an opportunity to replace vertical featureless walls with more complex and productive habitat. Several years before the new seawall was designed, the City of Seattle invited University of Washington biologists to participate in developing concepts for improved seawall habitat. This resulted in collaborations with several City of Seattle departments, during which we designed, deployed, and evaluated large habitat panels that tested several types of slopes and textures. Four years of monitoring algae, sessile invertebrates, and epibenthic organisms demonstrated that important biological “ecosystem engineers” benefited from adding texture and relief to seawalls. For example, compared to simple flat treatments and the existing seawall, recruitment of mussels was increased on panels with cobble texture, and rockweed was more abundant on high relief “finned” and “stepped” panels. Species richness of biota was also higher on surfaces with higher habitat complexity. This project represents a successful test of ecological engineering concepts, and the findings are being incorporated into the seawall that is currently being built. The City’s 10-year monitoring and adaptive management plan will allow for continued evaluation of these types of habitat enhancements on a larger scale. Invited comment: Mark Mazzola, Environmental Manager for the Seattle Department of Transportatio

INTERVIEW: Knowledge and Terminology Management at the Danish National Board of Social Services

Margrethe H. Møller interviews David Rosendahl(translator/coauthor: Birthe Toft)“We need to do more than simply create classifications” The concept secretariat of the Danish National Board of Social Services carries out terminology and classification work in connection with IT projects, among others, in the field of social services. This work is interesting for several reasons. On the one hand, terminology work obviously contributes to enhanced efficiency and transparency from the points of view of all types of users. On the other hand, some social services professionals are skeptical vis-à-vis the terminology projects because they fear unification and standardization of their professionalism and working procedures in connection with the introduction of new IT systems. And finally, a number of ethical issues have to be taken into consideration when deciding on terminology in the social services field. All in all, target group and communicative aspects become central to the effort.David Rosendahl Terminology consultant at the Danish National Board of Social ServicesThe Danish National Board of Social Services(“Socialstyrelsen”) is an independent subdivision of The Ministry of Social Affairs and Integration. The Board aims to promote new development and initiatives in social services while also supporting and counselling local authorities in providing services to citizens, i.e. children, young people, socially marginalised groups, elderly and disabled

Shoreline Monitoring Toolbox: Development and Goals for Implementation

Shoreline monitoring is often a desired or required goal by volunteer groups and local entities, but protocols and guidelines can be hard to find and misleading if not used appropriately. We will present the initial developments of a Shoreline Monitoring Toolbox, an idea that progressed from its original concept at the Shoreline Restoration Monitoring Consortium in June 2013. Among the issues are the needs of local entities for a standardized approach for monitoring and a “toolbox” of protocols and information. Emphasis is placed on methods that are simple and affordable, and that can be used for monitoring restoration sites, establishing baseline conditions, and evaluating status and trends and preservation efforts. The toolbox is coordinated with the PSEMP Nearshore Work Group in order to establish a foundation of technical expertise. Most of the effort so far has been to (1) organize a decision tree that will help guide monitoring choices, and (2) organize protocols that are not well known or might be lost if not in digital form. The goal is to provide the toolbox as a web-based platform that will build upon other resources to fill gaps of monitoring needs. In this process, science will help inform decisions to catalyze action by (1) providing effective guidance for how to monitor, (2) informing groups on how to move forward in their goals, and (3) providing a feedback loop of completed projects that can inform future projects. An example will be given of how completed restoration monitoring at the Olympic Sculpture Park (Seattle, WA) was useful to guide local shoreline planning, but the technical methods were difficult to apply when taken out of context to other efforts such as at Carpenter Creek Estuary (Kingston, WA). Invited comment from the Stillwaters Environmental Center will discuss how volunteer monitoring efforts were established, and how a toolbox would have and hopefully will better organize monitoring efforts in the future

Accelerated recovery of postischemic stunned myocardium after induced expression of myocardial heat-shock protein (HSP70)

AbstractIn vitro studies suggest that interventions targeted at myocardial gene regulation of endogenous cytoprotective elements, such as heat-shock protein, may attenuate myocardial ischemic injury. We tested the hypothesis that heat shock-induced expression of myocardial heat-shock protein before ischemia accelerates functional recovery of postischemic stunned myocardium in the intact circulation. Sixteen dogs underwent partial femoral arteriovenous bypass and core temperature was raised to 42° C for 15 minutes in eight dogs (heat-shocked) and maintained at 37° C in eight dogs (nonheat-shocked). After 24 hours dogs were studied to measure myocardial segment length in the circumflex artery region with ultrasonic dimension transducers, left ventricular pressure with a micromanometer, and circumflex coronary flow with an ultrasonic probe. Regional contractile function was quantified by the area beneath the linear preload recruitable stroke work relationship at baseline and at intervals during reperfusion after a 15-minute circumflex artery occlusion followed by 3 hours of reperfusion. Baseline and peak reperfusion hyperemic circumflex flows were 37 ± 9 ml/min and 154 ± 33 ml/min, respectively, in heat-shocked dogs (p < 0.001) and 46 ± 24 ml/min and 171 ± 57 ml/min, respectively, in nonheat-shocked dogs (p < 0.001), with no differences between groups (p = not significant) at any time during reperfusion. Heart rate and left ventricular peak pressure, end-diastolic pressure, and first derivative of left ventricular pressure were similar (all p = not significant) in heat-shocked and nonheat-shocked dogs during ischemia and reperfusion. Before ischemia, preload recruitable stroke work relationship did not differ (p = not significant) in heat-shocked and nonheat-shocked dogs. Ischemia reduced preload recruitable stroke work relationship to 32% ± 8% control (p < 0.001) in heat-shocked dogs and to 19% ± 15% control in nonheat-shocked dogs (p < 0.001) at 15 minutes of reperfusion, indicating a similar (p = not significant) initial degree of injury. During 3 hours of reperfusion, preload recruitable stroke work relationship returned to 80% ± 38% control in heat-shocked dogs but to only 33% ± 13% control in nonheat-shocked dogs (p < 0.0001). Myocardial expression of heat-shock protein, quantified by optical densitometry of Western blots using an antibody specific for HSP70, was greater in heat-shocked than in nonheat-shocked dogs (108 ± 27 versus 71 ± 14 densitometry units, p < 0.005). Exact causal mechanisms remain to be defined, but these data indicate (1) hyperthermic bypass triggers induction of myocardial heat-shock protein and (2) elevated myocardial heat-shock protein is associated with accelerated recovery of stunned myocardium. Promotion of endogenous molecular cytoprotective systems represents a novel and potentially useful strategy for myocardial protection. (J THORAC CARDIOVASC SURG 1995;109:753-64

Prevalence of paratuberculosis in the dairy goat and dairy sheep industries in Ontario, Canada

A cross-sectional study was undertaken (October 2010 to August 2011) to estimate the prevalence of paratuberculosis in the small ruminant dairy industries in Ontario, Canada. Blood and feces were sampled from 580 goats and 397 sheep (lactating and 2 y of age or older) that were randomly selected from 29 randomly selected dairy goat herds and 21 convenience-selected dairy sheep flocks. Fecal samples were analyzed using bacterial culture (BD BACTEC MGIT 960) and polymerase chain reaction (Tetracore); serum samples were tested with the Prionics Parachek enzyme-linked immunosorbent assay (ELISA). Using 3-test latent class Bayesian models, true farm-level prevalence was estimated to be 83.0% [95% probability interval (PI): 62.6% to 98.1%] for dairy goats and 66.8% (95% PI: 41.6% to 91.4%) for dairy sheep. The within-farm true prevalence for dairy goats was 35.2% (95% PI: 23.0% to 49.8%) and for dairy sheep was 48.3% (95% PI: 27.6% to 74.3%). These data indicate that a paratuberculosis control program for small ruminants is needed in Ontario

Shoreline armoring disrupts marine-terrestrial connectivity in the Salish Sea, with consequences for invertebrates, fish, and birds

Within the marine-terrestrial ecotone, upper intertidal “wrack zones” accumulate organic debris from algae, seagrass, and terrestrial plant sources and provide food and shelter for many organisms. We conducted detailed surveys of wrack and log accumulations and supralittoral invertebrates in spring and fall over 3 years at 29 armored-unarmored beach pairs in Puget Sound, WA, USA. Additionally, behavioral observations of juvenile salmon (Oncorhynchus spp.) and birds were conducted at 6 pairs. Armored beaches had substantially less wrack overall, a lower proportion of terrestrial plant material in the wrack, and far fewer logs. Armored beaches had significantly fewer invertebrates and differed from unarmored beaches in their taxonomic composition. Unarmored invertebrate assemblages were dominated by talitrid amphipods and insects, and were correlated with the amount of beach wrack and logs, the proportion of terrestrial material in wrack, and the maximum elevation of the beach. Shoreline armoring influenced juvenile salmon distribution, with fewer overall observations and fish in deeper water at armored beaches, but their feeding rates were relatively high at all sites. Terrestrial birds were commonly observed foraging among beach wrack and logs at unarmored beaches, but were largely absent from armored beaches. This study demonstrates that shoreline armoring disrupts marine-terrestrial connectivity, affecting the amount and type of organic material delivered to the nearshore ecotone in the form of wrack and logs, the abundance and taxonomic composition of supralittoral invertebrates, and the distribution and behavior of secondary consumers (juvenile salmon and birds)

Grain boundary-induced variability of charge transport in hydrogenated polycrystalline graphene

Chemical functionalization has proven to be a promising means of tailoring the unique properties of graphene. For example, hydrogenation can yield a variety of interesting effects, including a metal-insulator transition or the formation of localized magnetic moments. Meanwhile, graphene grown by chemical vapor deposition is the most suitable for large-scale production, but the resulting material tends to be polycrystalline. Up to now there has been relatively little focus on how chemical functionalization, and hydrogenation in particular, impacts the properties of polycrystalline graphene. In this work, we use numerical simulations to study the electrical properties of hydrogenated polycrystalline graphene. We find a strong correlation between the spatial distribution of the hydrogen adsorbates and the charge transport properties. Charge transport is weakly sensitive to hydrogenation when adsorbates are confined to the grain boundaries, while a uniform distribution of hydrogen degrades the electronic mobility. This difference stems from the formation of the hydrogen-induced resonant impurity states, which are inhibited when the honeycomb symmetry is locally broken by the grain boundaries. These findings suggest a tunability of electrical transport of polycrystalline graphene through selective hydrogen functionalization, and also have implications for hydrogen-induced magnetization and spin lifetime of this material

Upper Mantle Pollution during Afar Plume-Continental Rift Interaction

International audienceNew Pb, Sr, Nd, Hf, and He isotope data for Quaternary basalts, erupted from Debre Zeyit, Butajira, and the Wonji Fault Belt of the Main Ethiopian Rift, show systematic mixing relationships involving three distinct mantle sources. The Pb, Sr, Nd, and Hf isotopic arrays converge in a specific region of isotopic multi-space where they define the composition of the Afar mantle plume (centered about (206)Pb/(204)Pb = 19 center dot 5, (87)Sr/(86)Sr = 0 center dot 7035, epsilon(Nd) = +4 center dot 6, epsilon(Hf) = +9 center dot 3, (3)He/(4)He > 15 R(A)). This plume end-member has an identical composition to that observed previously in oceanic basalts. The distinct isotopic arrays for the various volcanic areas in the Main Ethiopian Rift vary spatially in a systematic manner, and may be viewed as pseudo-binary mixing arrays. This further suggests that the Afar mantle plume interacts with the local continental lithosphere and upper mantle asthenosphere (mid-ocean ridge basalt-like source) through an ordered sequence of mixing events. Simple mixing models require that the mass proportions of continental lithosphere and upper mantle involved in magma generation must be nearly constant within each volcanic area, but that the proportion of plume material decreases regularly with distance southwestward along the Main Ethiopian Rift, away from the central axis of the plume. This systematic behavior means that continental lithosphere can become detached and mixed into the shallow mantle prior to the flow of upwelling plume material beneath the developing rift system. Detachment and mixing into the asthenosphere during continental rift evolution is an important process for producing the range of ambient upper mantle compositions sampled by mid-ocean ridge volcanism away from island hotspots

Direct observation of the Higgs amplitude mode in a two-dimensional quantum antiferromagnet near the quantum critical point

Spontaneous symmetry-breaking quantum phase transitions play an essential role in condensed matter physics. The collective excitations in the broken-symmetry phase near the quantum critical point can be characterized by fluctuations of phase and amplitude of the order parameter. The phase oscillations correspond to the massless Nambu$-$Goldstone modes whereas the massive amplitude mode, analogous to the Higgs boson in particle physics, is prone to decay into a pair of low-energy Nambu$-$Goldstone modes in low dimensions. Especially, observation of a Higgs amplitude mode in two dimensions is an outstanding experimental challenge. Here, using the inelastic neutron scattering and applying the bond-operator theory, we directly and unambiguously identify the Higgs amplitude mode in a two-dimensional S=1/2 quantum antiferromagnet C$_9$H$_{18}$N$_2$CuBr$_4$ near a quantum critical point in two dimensions. Owing to an anisotropic energy gap, it kinematically prevents such decay and the Higgs amplitude mode acquires an infinite lifetime.Comment: 12 pages, 4 figures in the main text+3 figures in Supplementary Informatio