Replacing coal with wood: sustainable, eco-neutral, conservation harvest of natural tree-fall in old-growth forests

Kleidon (2009) concludes that warm climates impose important constraints on the evolution of large brains relative to body size, confirming our previous hypothesis (Schwartzman and Middendorf 2000). Here we update the case for our hypothesis and present a first approximation estimate of the cooling required for hominin brain size increase using a simple model of heat loss. We conclude that Pleistocene glacial episodes were likely sufficient to serve as prime releasers for emergence of Homo habilis and Homo erectus. In addition, we propose that atmospheric oxygen levels may been an analogous constraint on insect encephalization.     

North polar hood observations during Martian dust storms

The 1956, 1971, and 1973 major dust storms on Mars affected the apparent contrast and extent of the northern polar hood. A survey of photography from seven apparitions indicates that this seasonal feature is consistently prominent and identifiable in the absence of major storms throughout half of the Martian year. During the 1956 dust storm, the hood was not seen for a period of over one month on Lowell photographs. The effects of a storm are also seen on 1971 International Planetary Patrol photographs; the hood quickly became faint and tenuous even in ultraviolet light, which normally shows it as very bright.Patrol photographs of 1973 cover the complete progression from a prominent and extensive hood before the storm, to an intermittent disappearance at the height of the storm, to the subsequent return of a normal hood as the storm died out. Hourly and daily mapping from these photographs indicates that the hood developed a southward protrusion during the first few days of the storm as it began its apparent recession. The hood was seen on at least one side of the planet on every day throughout the duration of the storm, although its normal extent and contrast were greatly reduced.     

A sea bottom multichannel hydrophone array

The PUMA (Pull-Up Multichannel Array) is a sea-bottom instrument for remotely recording data from a 12 channel hydrophone array. Its purpose is to achieve (i) denser data coverage, leading to (ii) improved velocity analysis and (iii) multichannel processing of wide angle seismic data collected on the continental shelf. The instrument consists of a 1.2 km array terminating with a pressure case in which 8 FM cassette recorders, a power supply, microprocessor controller and internal clock are housed. It can be pre-programmed to switch on during shot windows for a total of four hours recording time.The PUMA was successfully used in an experiment west of Lewis, Outer Hebrides, U.K. in August–September 1984. We show an example of PUMA data from this experiment. Indications are that the instrument will provide improved constraints on seismic velocities in the lower continental crust and uppermost mantle.     

Lateral stability of a submarine flexible hoseline

The lateral stability of a submarine hoseline in a slowly varying current is investigated. If the current force overcomes the sea bottom resistance, the hose segment is assumed to slide on the sea bottom without twisting. The stability is evaluated in terms of lateral deflections, hose tensions, and anchor loads. The behavior of a hoseline in a variable current is simulated based on nonlinear cable-like response to lift and Morison-type drag forces. Principles and the numerical algorithm of the simulation model are briefly summarized. A parametric analysis is conducted to study the influence on the hose response of the physical parameters considered in the simulation model. The results indicate that, for a practical hoseline, the most critical parameters are: the segment length-to-span ratio, the axial rigidity of the hose, the hose size, and the current velocity. The sea bottom resistance is negligible from a design point of view.     

On the Classification of Meteorites

The classification of meteorites as a whole is briefly presented and discussed; in particular, it is pointed out that the intermediate or transitional group, now universally known as the siderolites (symbol, So), consists of 2 main subdivisions, namely the “irony stones,” hereinafter termed sideraerolites (Sa), and the “stony irons” or so-called lithosiderites (Li).     

Spatio-Temporal Surface Shear-Stress Variability in Live Plant Canopies and Cube Arrays

This study presents spatiotemporally-resolved measurements of surface shear-stress τ _s in live plant canopies and rigid wooden cube arrays to identify the sheltering capability against sediment erosion of these different roughness elements. Live plants have highly irregular structures that can be extremely flexible and porous resulting in considerable changes to the drag and flow regimes relative to rigid imitations mainly used in other wind-tunnel studies. Mean velocity and kinematic Reynolds stress profiles show that well-developed natural boundary layers were generated above the 8 m long wind-tunnel test section covered with the roughness elements at four different roughness densities (λ = 0, 0.017, 0.08, 0.18). Speed-up around the cubes caused higher peak surface shear stress than in experiments with plants at all roughness densities, demonstrating the more effective sheltering ability of the plants. The sheltered areas in the lee of the plants are significantly narrower with higher surface shear stress than those found in the lee of the cubes, and are dependent on the wind speed due to the plants ability to streamline with the flow. This streamlining behaviour results in a decreasing sheltering effect at increasing wind speeds and in lower net turbulence production than in experiments with cubes. Turbulence intensity distributions suggest a suppression of horseshoe vortices in the plant case. Comparison of the surface shear-stress measurements with sediment erosion patterns shows that the fraction of time a threshold skin friction velocity is exceeded can be used to assess erosion of, and deposition on, that surface.     

Phytoplankton dynamics within Gulf Stream intrusions on the southeastern United States continental shelf during summer 1981

During July and August 1981 subsurface intrusion of upwelled nutrient-rich Gulf Stream water was the dominant process affecting temporal and spatial changes in phytoplankton biomass and productivity of the southeastern United States continental shelf between 29 and 32°N latitude. Intruded waters in the study area covered as much as 10¹ km including virtually all of the middle and outer shelf and approximately 50% of the inner shelf area.Within 2 weeks following a large intrusion event in late July, middle shelf primary production and Chl a reached 3 to 4 gC m⁻ d⁻¹ and 75 mg m⁻, respectively. At the peak of the bloom 80% of the water column primary production occurred below the surface mixed-layer, and new primary production (i.e., NO₃-supported) exceeded 90% of the total. Chl a-normalized photosynthetic rates were very high as evidenced by high mean assimilation number (15.5 mg C mg Chl a⁻¹ h⁻¹), high mean α (14 mg C mg Chl a⁻¹ Ein⁻¹ m), and no photoinhibition. As a result of the high photosynthetic rates, mean light-utilization index (Ψ) was 2 to 3 times higher than reported for temperature sub-arctic and arctic waters.The results imply a seasonal (June to August) middle shelf production of 150 g C m⁻¹, about 15% higher than previous estimates of annual production on the middle shelf. Intrusions of the scale we observed in 1981 may not occur every summer. However, when such events do occur, they are by far the most important processes controlling summer phytoplankton dynamics of the middle and outer shelf and of the inner shelf in the southern half of the study area.     

REVISION OF ORDNANCE SURVEY 1:2500 SCALE MAPS

With the completion of its programme to produce a national series of 1:2500 scale maps of rural areas, the Ordnance Survey is now faced with the major task of maintaining it up to date and making the revision information available to map users. The organisation and techniques for this are discussed, as are a number of innovations which are being considered.

Résumé

Avec l'achèvement du programme de réalisation de la série cartographique nationale à l'échelle du 1:2500 des régions rurales, l'Ordnance Survey doit maintenant faire face au maintien à jour de cette série et à la mise à disposition des usagers des données de révision, ce qui va constituer sa tâche principale. Une discussion sur l'organisation et les techniques correspondantes est fournie, prenant en compte l'examen de nombreuses innovations.

Zusammenfassung

Nach Fertigstellung der Kane 1:2500 von ländlichen Gebieten besteht für den Ordnance Survey jetzt die Aufgabe, diese Karte laufend zu halten und die Ergänzungen den Kartennutzern bereitzusteller. Diskussion der Organisation und Verfahren dafür sowie einiger Neuerungen, die in Erwägung gezogen werden.     

Upper-ocean heat budget and ocean eddy transport in the south-east Pacific in a high-resolution coupled model

We present an analysis of the oceanic heat advection and its variability in the upper 500 m in the southeastern tropical Pacific (100W–75W, 25S–10S) as simulated by the global coupled model HiGEM, which has one of the highest resolutions currently used in long-term integrations. The simulated climatology represents a temperature advection field arising from transient small-scale (<450 km) features, with structures and transport that appear consistent with estimates based on available observational data for the mooring at 20S, 85W. The transient structures are very persistent (>4 months), and in specific locations they generate an important contribution to the local upper-ocean heat budget, characterised by scales of a few hundred kilometres, and periods of over a year. The contribution from such structures to the local, long-term oceanic heat budget however can be of either sign, or vanishing, depending on the location; and, although there appears some organisation in preferential areas of activity, the average over the entire region is small. While several different mechanisms may be responsible for the temperature advection by transients, we find that a significant, and possibly dominant, component is associated with vortices embedded in the large-scale, climatological salinity gradient associated with the fresh intrusion of mid-latitude intermediate water which penetrates north-westward beneath the tropical thermocline.