Past and present effects of propagule pressure on spatial distributions of non-native woody plants in central Texas

textMany recent studies have demonstrated that propagule pressure is a useful predictor of patterns of invasions by non-native species. However, most of these studies have used only current, not historical, data to estimate propagule pressure. Recognizing the potential importance of propagule pressure over time, I used surrogate variables that represent both past and present propagule pressure, for example, the length of time a surrounding area had been developed. I quantified the relationships between these surrogate variables and the distribution and abundance of non-native woody plant species in central Texas. I constructed statistical models predicting native and non-native species richness and the occurrence of five common species using a set of six ecological and five development-related predictor variables. I compared all models using the corrected Akaike information criterion (AICc). Overall, age of residential development surrounding native woodlands was the best predictor, other than community type, of non-native species richness. As expected, areas near older developments had more non-native species than areas near newer developments. Surprisingly, age of development and average city age, two different measures of the length of time that landscaping (a major source of propagules of non-native woody species in this region) had been present nearby, were much better predictors than distance to source populations. Age of development and average city age (weighted by distance from the site) were also both correlated with distance to source populations; this may be true in other systems as well. This suggests that the reason distance to source population has been a successful predictor of invasion may be because it is a surrogate for an underlying causal variable, length of time of exposure to source populations. Future studies of non-native invasions would benefit from taking into account both past and present propagule pressure: age of residential development and city age could be useful surrogates in other systems.Plant Biolog

Classification of African ecosystems at 1 km resolution using multiannual SPOT/VEGETATION data and a hybrid clustering approach

Ecosystems classification is the process of allocating vegetation types into groups so that individuals in the same class are similar according to their physiological and phonological characteristics to another one. Over large areas, the only suitable technique to obtain frequent and repetitive data acquisitions over such large areas is the use of observations recorded by sensors of moderate resolution. In order to minimize the role of the analyst and to improve the accuracy of the results, innovative and efficient approaches for the classification of ecosystems continue to appear in the literature. This research developed and implemented a new hybrid unsupervised classification approach to derive ecosystems using multi-annual time series by combining hierarchical and partitioning clustering principles. The latter approach is applied on 8-years time series (2000-2007) of 10-day composite Normalized Difference Vegetation Index (NDVI) recorded by SPOT/VEGETATION. After the first segmentation of the mainland in ecoregions using the Fast Fourier Transform (FFT), successive k-nearest neighbor (k-NN) clustering enhance the discrimination of ecosystems and yields to the production of a new ecosystem map for the African continent. The nomenclature relied on the Land Cover Classification System (LCCS) of the Food and Agricultural Organization (FAO). On the basis of validated continental, a pixel-by-pixel analysis is conducted to assess the accuracy of the new classification. The hybrid clustering facilitates the identification/labeling process and the obtained results which should provide key information needed for management/monitoring of natural resources, biodiversity conservation and biogeochemical studies may also deserve vegetation cover modeling at regional and local scal

Quantifying burned area for North American forests: Implications for direct reduction of carbon stocks

A synthesis was carried out to analyze information available to quantify fire activity and burned area across North America, including a comparison of different data sources and an assessment of how variations in burned area estimate impact carbon emissions from fires. Data sets maintained by fire management agencies provide the longest record of burned area information. Canada and Alaska have the most well developed data sets consisting of the perimeters of large fires (\u3e200 ha) going back to 1959 and 1950, respectively. A similar data set back to 1980 exists for the Conterminous U.S., but contains data only from federal land management agencies. During the early half of the 20th century, average burned area across North America ranged between 10 and 20 × 106 ha yr−1, largely because of frequent surface fires in the southeastern U.S. Over the past two decades, an average of 5 × 106 ha yr−1 has burned. Moderate-resolution (500–1000 m) satellite burned area products information products appear to either underestimate burned area (GFED3 and MCD45A1) or significantly overestimate burned area (L3JRC and GLOBCARBON). Of all the satellite data products, the GFED3 data set provides the most consistent source of burned area when compared to fire management data. Because they do not suitably reflect actual fire activity, the L3JRC and GLOBCARBON burned area data sets are not suitable for use in carbon cycle studies in North America. The MCD45A1 data set appears to map a higher fraction of burned area in low biomass areas compared to the GFED3 data set

Prohibiting alcohol sales during the coronavirus disease 2019 pandemic has positive effects on health services in South Africa

Reuter H, Jenkins LS, De Jong M, Reid S, Vonk M. Prohibiting alcohol sales during the coronavirus disease 2019 pandemic has positive effects on health services in South Africa. Afr J Prm Health Care Fam Med. 2020;12(1), a2528.As the coronavirus disease 2019 (Covid-19) pandemic evolves globally, we are realising its impact on communities from the disease itself and the measures being taken to limit infection spread. In South Africa (SA), 62 300 adults die annually from alcohol-attributable causes. Alcohol-related harm can be reduced by interventions, such as taxation, government monopolising retail sales, outlet density restriction, hours of sales and an advertising ban. To mitigate the impact of the Covid-19 pandemic, SA instituted a lockdown that also prohibited alcohol sales. This led to a sharp reduction in unnatural deaths in the country from 800–1000/week to around 400/week during the lockdown. We reviewed three 2-week periods at a large rural regional hospital: Before Covid-19 (February), during social distancing (March) and during lockdown with alcohol ban (April). A dramatic drop in patient numbers from 145 to 64 (55.8%) because of assault, from 207 to 83 (59.9%) because of accidents, from 463 to 188 (59.4%) because of other injuries and from 12 to 1 (91.6%) because of sexual assaults was observed during the first 2 weeks of lockdown. As healthcare professionals, we need to advocate for the ban to remain until the crisis is over to ensure that health services can concentrate on Covid-19 and other patients. We encourage other African states to follow suit and implement alcohol restrictions as a mechanism to free up health services. We see this as an encouragement to lobby for a new normal around alco

Особенности трансформации символа креста на территории средневековой Таврики

BACKGROUND: Cow's milk-derived whey hydrolysates are nutritional substitutes for allergic infants. Safety or residual allergenicity assessment of these whey hydrolysates is crucial. Currently, rat basophilic leukemia RBL-2H3 cells expressing the human IgE receptor α-chain (huFcεRIα-RBL-2H3), sensitized with serum IgE from cow's milk allergic children, are being employed to assess in vitro residual allergenicity of these whey hydrolysates. However, limited availability and inter-lot variation of these allergic sera impede standardization of whey hydrolysate safety testing in degranulation assays. OBJECTIVE: An oligoclonal pool of chimeric human (chu)IgE antibodies against bovine β-lactoglobulin (a major allergen in whey) was generated to increase sensitivity, specificity, and reproducibility of existing degranulation assays. METHODS: Mice were immunized with bovine β-lactoglobulin, and subsequently the variable domains of dissimilar anti-β-lactoglobulin mouse IgG antibodies were cloned and sequenced. Six chimeric antibodies were generated comprising mouse variable domains and human constant IgE/κ domains. RESULTS: After sensitization with this pool of anti-β-lactoglobulin chuIgEs, huFcεRIα-expressing RBL-2H3 cells demonstrated degranulation upon cross-linking with whey, native 18 kDa β-lactoglobulin, and 5-10 kDa whey hydrolysates, whereas a 3 kDa whey hydrolysate and cow's milk powder (mainly casein) showed no degranulation. In parallel, allergic serum IgEs were less sensitive. In addition, our pool anti-β-lactoglobulin chuIgEs recognized multiple allergenic immunodominant regions on β-lactoglobulin, which were also recognized by serum IgEs from cow's milk allergic children. CONCLUSION: Usage of our 'unlimited' source and well-defined pool of β-lactoglobulin-specific recombinant chuIgEs to sensitize huFcεRIα on RBL-2H3 cells showed to be a relevant and sensitive alternative for serum IgEs from cow's milk allergic patients to assess safety of whey-based non-allergic hydrolyzed formula

Semi-classical Theory of Conductance and Noise in Open Chaotic Cavities

Conductance and shot noise of an open cavity with diffusive boundary scattering are calculated within the Boltzmann-Langevin approach. In particular, conductance contains a non-universal geometric contribution, originating from the presence of open contacts. Subsequently, universal expressions for multi-terminal conductance and noise valid for all chaotic cavities are obtained classically basing on the fact that the distribution function in the cavity depends only on energy and using the principle of minimal correlations.Comment: 4 pages, 1 .eps figur

Shot Noise in Mesoscopic Conductors

Theoretical and experimental work concerned with dynamic fluctuations has developed into a very active and fascinating subfield of mesoscopic physics. We present a review of this development focusing on shot noise in small electric conductors. Shot noise is a consequence of the quantization of charge. It can be used to obtain information on a system which is not available through conductance measurements. In particular, shot noise experiments can determine the charge and statistics of the quasiparticles relevant for transport, and reveal information on the potential profile and internal energy scales of mesoscopic systems. Shot noise is generally more sensitive to the effects of electron-electron interactions than the average conductance. We present a discussion based on the conceptually transparent scattering approach and on the classical Langevin and Boltzmann-Langevin methods; in addition a discussion of results which cannot be obtained by these methods is provided. We conclude the review by pointing out a number of unsolved problems and an outlook on the likely future development of the field.Comment: 99 two-column pages; 38 .eps figures included. Submitted to Physics Reports. Many minor improvements; typos corrected; references added and update