Some thoughts on pulsation and binarity

Intensive monitoring of main-sequence stars for pulsational studies continuously reveals new binaries and multiple systems. The resulting extensive data sets lead to exact orbital parameters, and to accurate masses of the components. This is also the case higher up the main sequence, though less frequently. We discuss a few examples where intensive observational efforts are necessary in order to improve our knowledge of the pulsational behaviour in the upper main-sequence instability domains, but we emphasize that observational efforts alone that turn out more and more of the same type of data, are by far insufficient, and that there is urgent need for theoretical developments. Determination of highly accurate stellar parameters is of paramount importance and is much more needed than time-series observations.     

Characterisation of hydroclimatological trends and variability in the Lake Naivasha basin,Kenya

Recent hydro‐climatological trends and variability characteristics were investigated for the Lake Naivasha basin with the aim of understanding the changes in water balance components and their evolution over the past 50 years. Using a Bayesian change point analysis and modified Mann–Kendall tests, time series of annual mean, maximum, minimum, and seasonal precipitation and flow, as well as annual mean lake volumes, were analysed for the period 1960–2010 to uncover possible abrupt shifts and gradual trends. Double cumulative curve analysis was used to investigate the changes in hydrological response attributable to either human influence or climatic variability. The results indicate a significant decline in lake volumes at a mean rate of 9.35 × 10⁶ m³ year^?1. Most of the river gauging stations showed no evidence of trends in the annual mean and maximum flows as well as seasonal flows. Annual minimum flows, however, showed abrupt shifts and significant (upward/downward) trends at the main outlet stations. Precipitation in the basin showed no evidence of abrupt shifts, but a few stations showed gradual decline. The observed changes in precipitation could not explain the decline in both minimum flows and lake volumes. The findings show no evidence of any impact of climate change for the Lake Naivasha basin over the past 50 years. This implies that other factors, such as changes in land cover and infrastructure development, have been responsible for the observed changes in streamflow and lake volumes. Copyright © 2015 John Wiley & Sons, Ltd.     

Holocene Alluvial Chronology of One Tree Creek, Southern Alberta, Canada

An alluvial chronology for the One Tree Creek basin, a southern tributary of the Red Deer River in southern Alberta, is reconstructed using terrace and palaeochannel remnants and associated radiocarbon dated bones. Prior to the development of One Tree Creek as a northeastward flowing tributary, the prairie surface was scoured by proglacial floodwaters decanting from Glacial Lake Bassano/Patricia in the west. Radiocarbon dates on bones from the bedload gravels in palaeochannels provide a morphochronology of Holocene stream incision. Tentative average incision rates for the middle and upper reaches are calculated at 0.34–0.38 cm a^‐1 since 2.8 ka BP and 0.80 – 1.60 cm and 0.81 – 0.96 cm a^‐1 for the two periods of 1870 to 1230 BP and 1230 BP to modern respectively. Terraces and palaeochannels dating to the period of highest incision (1870 BP to modern) include numerous reworked bones dating to earlier periods, indicating that fluvial downcutting triggered slope instability and terrace reworking. Although the lower bedrock reaches of the creek may have incised down to the present level of the Red Deer River during early postglacial time, the middle and upper reaches were rapidly incised into Quaternary sediments during the late Holocene when climatic conditions were more humid.     

Economic Hotspots: Visualizing Vulnerability to Flooding

We simulate a large-scale flooding in the province of South-Holland in the economic centre of the Netherlands. In traditional research, damage due to flooding is computed with a unit loss method coupling land use information to depth-damage functions. Normally only direct costs are incorporated as an estimate of damage to infrastructure, property and business disruption. We extend this damage concept with the indirect economic effects on the rest of the regional and national economy on basis of a bi-regional input output table.We broaden this damage estimation to the concept of vulnerability. Vulnerability is defined as a function of dependence, redundancy and susceptibility. Susceptibility is the probability and extent of flooding. Dependency is the degree to which an activity relates to other economic activities in the rest of the country. Input–output multipliers form representations of this dependency. Redundancy is the ability of an economic activity to respond to a disaster by deferring, using substitutes or relocating. We measure redundancy as the degree of centrality of an economic activity in a network. The more central an activity is, the less it encounters possibilities to transfer production and the more vulnerable it is for flooding. Vulnerability of economic activities is then visualized in a GIS. Kernel density estimation is applied to generalize point information on inundated firms to sectoral information in space. We apply spatial interpolation techniques for the whole of the province of South-Holland. Combining information of sectoral data on dependency and redundancy, we are able to create maps of economic hotspots. Our simulation of a flood in the centre of Holland reveals the vulnerability of a densely populated delta.     

A Global Dynamic Model for the Neolithic Transition

During the Holocene strong gradients in the distribution of technologyincluding subsistence ways emerged on a global scale.These patterns were further amplified in historic times and are stillvisible through worldwide differences in national wealth.In order to evaluate major factors responsible for the shift fromforaging to food production we here employ quantitative methods bydeveloping a deterministic but simple model. After compiling existing maps of potential vegetation at 5000 BP theinhabited world is split into 197 regions with homogeneous environmentalconditions. Suitable variables for the macro-economic and culturaldevelopment in the Neolithic period are found to be farming to hunting-gatheringratio, number of agricultural economies and a technological development index.The model explicitly describes economic adaptation, growth and migrationof human populations together with the spread of their cultural characteristics; it accounts for over-exploitation of natural resources, crowdingmortality and the climate variability on a millennium scale.In a thorough model validation region specific trajectories are compared toarchaeological evidence revealing a high correspondence. Major parts of the knownsequence of Neolithic centers including the timing differences are robustlyreproduced. A series of known problems in prehistory is discussedcomprising the lag between domestication and full scale farming, the off-levelingof the technological boost following the transition, the emergence ofdistinct migration waves and sensitivity to climate fluctuations.Not mere population pressure but continuous innovation and competition betweensubsistence strategies is identified as a prime mover of agricultural development.The results suggest that few aspects of biogeography may have determined theobserved continental gradients in the number of domesticable species ultimatelyleading to an increasing differentiation in technology and demography.     

Fossil chironomid assemblages and inferred summer temperatures for the past 14,000 years from a low-elevation lake in Pacific Canada

Fossil midge remains in a sediment core from Lake Stowell, a low-elevation lake in coastal British Columbia, Canada, were used to assess temporal changes in chironomid communities and to produce quantitative estimates of mean July air temperature (MJAT) for the past 14,000 years based on two different transfer functions. Chironomid assemblages are diverse throughout much of the record, with most taxa present at low relative abundances. The basal portion of the sediment record is characterized by low head capsule concentrations, taxonomic diversity and organic matter content, all of which increase towards the early Holocene. Inferred temperatures suggest a cool late-glacial interval with a minimum MJAT of 12.5 °C, ~2 °C cooler than the inferred modern temperature. Summer temperatures gradually increased from this minimum until a brief cooling of as much as ~3 °C relative to modern that coincides with the Younger Dryas chronozone. An interval of warmer summers with MJAT of ~16 to 18 °C (2–3 °C warmer than modern) is inferred between ~10,500 and 8000 cal year BP. This early Holocene warm period was followed by generally cooler inferred temperatures in the middle and late Holocene. The midge-inferred temperature record from Lake Stowell is generally consistent with other temperature reconstructions from the region based on chironomid remains and other climate proxies. This research underscores the potential of low-elevation, mid-latitude sites for chironomid-based temperature reconstructions. In order to maximize the availability of modern analogues for robust temperature reconstructions from similar sites, calibration datasets should be expanded to include more sites from the warm end of the temperature gradient.     

LavAtmos: An open-source chemical equilibrium vaporization code for lava worlds

To date, over 500 short-period rocky planets with equilibrium temperatures above 1500 K have been discovered. Such planets are expected to support magma oceans, providing a direct interface between the interior and the atmosphere. This provides a unique opportunity to gain insight into their interior compositions through atmospheric observations. A key process in doing such work is the vapor outgassing from the lava surface. LavAtmos is an open-source code that calculates the equilibrium chemical composition of vapor above a dry melt for a given composition and temperature. Results show that the produced output is in good agreement with the partial pressures obtained from experimental laboratory data as well as with other similar codes from literature. LavAtmos allows for the modeling of vaporization of a wide range of different mantle compositions of hot rocky exoplanets. In combination with atmospheric chemistry codes, this enables the characterization of interior compositions through atmospheric signatures.     

Small is profitable: No support for the optimal foraging theory in sea stars Asterias rubens foraging on the blue edible mussel Mytilus edulis

Doubt has been shed recently on the most popular optimal foraging theory stating that predators should maximize prey profitability, i.e., select that prey item that contains the highest energy content per handling time. We hypothesized that sea stars do not forage on blue mussels according to the classical optimal foraging theory but are actively avoiding damage that may be caused by e.g. capture of foraging on too-strong mussel shells, hence the sea stars will have a stronger preference for mussels that are smaller than the most profitable ones. Here we present experimental evidence of the sea star Asterias rubens as a predator that indeed chooses much smaller blue mussels Mytilus edulis to forage on than the most profitable ones. Hence this study does not support the optimal foraging theory. There may be other constraints involved in foraging than just optimizing energy intake, for example predators may also be concerned with preventing potential loss or damage of their foraging instruments.     

Solutions for 4D cadastre – with a case study on utility networks

The increasing complexity and flexibility of modern land use requires that cadastres need to manage information on the third and temporal (fourth) dimension. This article considers the registration of legal space of utility networks in cadastre in this 3D + time (=4D) context. A requirement analysis in three countries that have methods to register utility networks complying with their legal, organizational and technical structure (Turkey, the Netherlands and Queensland, Australia) is the basis for three alternatives for 4D cadastre to register utility networks. The three alternatives are analysed with respect to legal, organizational and technical cadastral requirements. This article presents a case study and a prototype from the Netherlands. In this country by law utilities are considered to be real estate objects with obligatory registration of ownership and geometry. This study shows that the 3D space and separate temporal attributes approach (state-based model) is a very promising solution to maintain temporal changes of utility networks and that this approach is to be preferred above the current practice, where the 3D and temporal aspects are not considered when registering a network.