For a graphical property P and a graph G, a subset S of vertices of G is a P-set if the subgraph induced by S has the property P. The domination number with respect to the property P, denoted by γP (G), is the minimum cardinality of a dominating P-set. We define the domination multisubdivision number with respect to P, denoted by msdP (G), as a minimum positive integer k such that there exists an edge which must be subdivided k times to change γP (G). In this paper (a) we present necessary and sufficient conditions for a change of γP (G) after subdividing an edge of G once, (b) we prove that if e is an edge of a graph G then γP (Ge,1) < γP (G) if and only if γP (G − e) < γP (G) (Ge,t denotes the graph obtained from G by subdivision of e with t vertices), (c) we also prove that for every edge of a graph G we have γP (G − e) 6 γP (Ge,3) ≤ γP (G − e) + 1, and (d) we show that msdP (G) 6 3, where P is hereditary and closed under union with K1.
Simultaneous measurements of chlorophyll (Chl) fluorescence and photosynthetic O2 evolution {P^ in leaf disks from Vicia faba (cv. Reina Blanca) leaves were doně during the first weeks of growth in order to evaluate the damage caused by methabenzthiazuron (MBT) under field conditions. The plants were treated at preemergence with two doses of MBT (0.25 .and 0,40 g m'^). Measurements were carried out at constant temperature and saturating CO2 concentration. During the first weeks after plant emergence both doses of herbicide were followed by a drop in and in some fluorescence parameters, such as Fy/Fn, and AF/Fn,' ratios, and in photochemical and non-photochemical quenching, qp and q^. At the same time, increases in minimal fluorescence (Fq and Fq') and in maximal (Fj„') and steady-state fluorescence (Fj) were aiso observed on application of saturating pulses. Fluorescence parameters gave a better indication of the damage caused to the photosynthetic systém than the measurements. The linear relationship found between OO2 and the effective quantum yield, AF/Fn,', suggests that the latter is a good measure of the quantum efficiency of photosynthesis in herbicide-treated plants. Moreover, plant tissues detoxified the herbicide and, one month after plant emergence, photosynthesis was fully recovered in herbicide-treated plants; biomass production recovered and even increased at the end of the growth period.
Water scarcity poses a major threat to food security and human health in Central America and is increasingly recognized as a pressing regional issues caused primarily by deforestation and population pressure. Tools that can reliably simulate the major components of the water balance with the limited data available and needed to drive management decision and protect water supplies in this region. Four adjacent forested headwater catchments in La Tigra National Park, Honduras, ranging in size from 70 to 635 ha were instrumented and discharge measured over a one year period. A semi-distributed water balance model was developed to characterize the bio-hydrology of the four catchments, one of which is primarily cloud forest cover. The water balance model simulated daily stream discharges well, with Nash Sutcliffe model efficiency (E) values ranging from 0.67 to 0.90. Analysis of calibrated model parameters showed that despite all watersheds having similar geologic substrata, the bio-hydrological response the cloud forest indicated less plantavailable water in the root zone and greater groundwater recharge than the non cloud forest cover catchments. This resulted in watershed discharge on a per area basis four times greater from the cloud forest than the other watersheds despite only relatively minor differences in annual rainfall. These results highlight the importance of biological factors (cloud forests in this case) for sustained provision of clean, potable water, and the need to protect the cloud forest areas from destruction, particularly in the populated areas of Central America.
The dynamics of the terrestrial ecosystems depend on interactions between a number of biogeochemical cycles (i.e. carbon, nutrient, and hydrological cycles) that may be modified by human actions. Conversely, terrestrial ecosystems are important components of these cycles that create the sources and sinks of important greenhouse gases (e.g. carbon dioxide, methane, nitrous oxide). Especially, carbon is exchanged naturally among these ecosystems and the atmosphere through photosynthesis, respiration, decomposition, and combustion processes. Continuous increase of atmospheric carbon dioxide (CO2) concentration has led to extensive research over the last two decades, during which more then 1 400 scientific papers describing impacts of elevated [CO2] (EC) on photosynthesis have been published. However, the degree of response is very variable, depending on species, growing conditions, mineral nutrition, and duration of CO2 enrichment. In this review, I have summarised the major physiological responses of plants, in particular of trees, to EC including molecular and primary, especially photosynthetic, physiological responses. Likewise, secondary (photosynthate translocation and plant water status) and tertiary whole plant responses including also plant to plant competition are shown.
The study of migration in the Czech lands in the early modern age should, in the author’s view, focus particularly on several basic questions. One of these is the cause of migration. Czech research has thus far tended to overlook the discussion discusion, where a Malthusian opinion on the fundamental significance of “overpopulation” is countered by opposing views that see the main cause of migration as being the appeal of the target regions. Other important question areas with regard to this migration are the supplementation of urban populations and not just the propertied classes that research tends to limit itself to. The regionalisation process in the Czech lands, viewed from the perspective of the intensity and direction of migration flows, geographic mobility in terms of social and professional categories, especially migration connected with the performance of various professions, questions about the links between migration and communication networks, the directions of migration flows and their forms (organised or unmethodical, forced or voluntary, seasonal or fluctuating), and the migration of marginal segments of the population. At the same time it is necessary to study the factors restricting migration, such as seigniorial agreement and the scope of the strengthening of serfdom, economic ties (inheritance rights), administrative boundaries (municipality, parish, estate, denomination, the geographical shape of the land), and the consequences of migration, for example, for life in the regions that the temporary migrants departed from, or for nationality developments in the country (shifts in language boundaries, Germanification of towns). This text also presents a systematic overview of the sources available in the Czech archives for the study of migration in the Czech lands in the early modern age.