Trapped solar wind He,Ne, and Ar and energetic He in Surveyor 3

The Apollo 12 mission brought back sections of the Surveyor 3 vehicle suitable for mass spectrometric studies of implanted solar wind and solar cosmic rays. Using this method, we have determined an average solar wind ⁴He flux of 6.1 × 10⁶ ions/cm² sec for the 31 months of exposure. We have also measured ⁴He/³He= 2700 ± 50;⁴He/²⁰Ne= 410 ± 30;²⁰Ne/²²Ne= 13.5 ± 0.2;²⁰Ne/³⁶Ar= 24.5 ± 2.5; and ³⁶Ar/³⁸Ar= 5.41 ± 0.20. These measurements provide solar wind values averaged over considerably longer periods of time than the Apollo Solar Wind Composition experiments and suggest that the short term SWC measurements during a period of high solar activity may not be a reliable measure of average solar wind composition.     

Sciaridae in lake sediments: indicators of catchment and stream contribution to fossil insect assemblages

The larval head capsules of Sciaridae (black fungus gnats) are transported into lakes from terrestrial habitats, in most cases via streams or rivers, and preserve well in lake sediments. The abundance of sciarid remains can provide information on the importance of terrestrial and running-water input into fossil insect assemblages in lake sediments if examined in relation to the number of fossils of aquatic insects such as the Chironomidae, Thaumaleidae, Ceratopogonidae, or Simuliidae. Here we describe fossil head capsules of sciarid larvae and provide an example of how these remains can be used to constrain past changes in taphonomic processes that influence fossil chironomid records.     

Impact of the Rhône and Durance valleys on sea-breeze circulation in the Marseille area

Sea-breeze dynamics in the Marseille area, in the south of France, is investigated in the framework of the ESCOMPTE experiment conducted during summer 2001 in order to evaluate the role of thermal circulations on pollutant transport and ventilation. Under particular attention in this paper is the sea-breeze channelling by the broad Rhône valley and the narrow Durance valley, both oriented nearly-north–south, i.e., perpendicular to the coastline, and its possible impact on the sea-breeze penetration, intensity and depth, which are key information for air pollution issues. One situation of slight synoptic pressure gradient leading to a northerly flow in the Rhône valley (25 June 2001) and one situation of a weak onshore prevailing synoptic wind (26 June 2001) are compared. The impact of the Rhône and Durance valleys on the sea-breeze dynamics on these two typical days is generalized to the whole ESCOMPTE observing period.The present study shows by combining simple scaling analysis with wind data from meteorological surface stations and Doppler lidars that (i) the Durance valley always affects the sea breeze by accelerating the flow. A consequence is that the Durance valley contributes to weaken the temperature gradient along the valley and thus the sea-breeze circulation. In some cases, the acceleration of the channelled flow in the Durance valley suppresses the sea-breeze flow by temperature gradient inhibition; (ii) the Rhône valley does not generally affect the sea breeze significantly. However, if the sea breeze is combined with an onshore flow, it leads to further penetration inland and intensification of the low-level southerly flow. In this situation, lateral constriction may accelerate the sea breeze. Simple scaling analysis suggests that Saint Paul (44.35°N, about 100 km from the coastline) is the lower limit where sea breeze can be affected by the Rhône valley. These conclusions have implications in air quality topics as channelled sea breeze may advect far inland pollutants which may be incorporated into long-range transport, particularly in the Durance valley.     

Households’ willingness to reduce pollution threats in the Poyang Lake region,southern China

Environmental threats to wetland ecosystems are increasing, and these ecosystems are becoming increasingly sensitive to human impacts, leading to deterioration of these already fragile ecosystems. Poyang Lake is the largest freshwater lake in China and one of the most important wetlands in the world. However, water pollution and related environmental changes have increasingly drawn the scientific community's attention. The goal of this paper is to provide insights into the environmental threats to the Poyang Lake region as perceived from the households’ perspective, and to investigate their willingness to pay for conservation of the lake's environment. We collected both primary and secondary data through a questionnaire delivered to 270 households and analysis of existing water monitoring data. The major threat confronting the Poyang lake region is water pollution; water quality, as represented by the total nitrogen (TN) and total phosphorus (TP) concentrations and by chemical oxygen demand (COD), suggests a moderate to severe degree of eutrophication. The situation has worsened in recent years, particularly due to high TN and TP in agricultural drainage water caused by increasingly intensive use of chemical fertilizers by local farmers. Most households were willing to pay to mitigate these threats, but the magnitude of the payment was related to a farmer's dependence on the lake for their production and daily life. The results of our analysis will help managers develop more effective environmental management policies.     

A Computer-Aided Learning Program for Teaching Effective Stress to Undergraduates

A Computer-Aided Learning (CAL) program has been developed as a support aid for students learning the principle of effective stress and its application. The program called ESP (Effective Stress Program) has evolved over a period of two years as a result of research into student learning. This paper discusses the development, use and evaluation of the latest version of the program ESP98. ESP98 is shown to be an effective support tool by outperforming the conventional methods of instruction. The key to the success of ESP98 is the high level of interaction which students experience. The nature of the interaction is centred on a mistake-induced dialogue where the student is provided with progressive and instant feedback and guided towards the final answer. ESP has been integrated into the curriculum at Heriot-Watt University for the past two years and is freely available for use by other teaching institutions by contacting the authors.     

Decoding the complex internal chemical structure of garnet porphyroblasts from the Zermatt area,Western Alps

Garnet is a prototypical mineral in metamorphic rocks because it commonly preserves chemical and textural features that can be used for untangling its metamorphic development. Large garnet porphyroblasts may show extremely complex internal structures as a result of a polycyclic growth history, deformation, and modification of growth structures by intra‐ and intercrystalline diffusion. The complex internal structure of garnet porphyroblasts from garnet–phengite schists (GPS) of the Zermatt area (Western Alps) has been successfully decoded. The centimetre‐sized garnet porphyroblasts are composed of granulite facies garnet fragments overgrown by a younger generation of grossular‐rich eclogite facies garnet. The early granulite facies garnet (G‐Grt) formed from low‐P, high‐T metamorphism during a pre‐Alpine orogenic event. The late garnet (E‐Grt) is typical of high‐pressure, low‐temperature (HPLT) metamorphism and can be related to Alpine subduction of the schists. Thus, the garnet of the GPS are polycyclic (polymetamorphic). G‐Grt formation occurred at ~670 MPa and 780°C, E‐Grt formed at ~1.7 GPa and 530°C. The G‐Grt is relatively rich in Prp and poor in Grs, while E‐Grt is rich in Grs and poor in Prp. The Alm content (mol.%) of G‐Grt is 68 of E‐Grt 55. After formation of E‐Grt between and around fragmented G‐Grt at 530°C, the GPS have been further subducted and reached a maximum temperature of 580°C before exhumation started. Garnet composition profiles indicate that the initially very sharp contacts between the granulite facies fragments of G‐Grt and fracture seals of HPLT garnet (E‐Grt) have been modified by cation diffusion. The profiles suggest that Ca did not exchange at the scale of 1 µm, whereas Fe and Mg did efficiently diffuse at the derived maximum temperature of 580°C for the GPS at the scale of 7–8 µm. The Grt–Grt diffusion profiles resulted from spending c. 10 Ma at 530–580°C along the P–T–t path. The measured Grt composition profiles are consistent with diffusivities of log D_MgFe = ?25.8 m²/s from modelled diffusion profiles. Mg loss by diffusion from G‐Grt is compensated by Fe gain by diffusion from E‐Grt to maintain charge balance. This leads to a distinctive Fe concentration profile typical of uphill diffusion.     

Precision spacecraft navigation using a low-cost GPS receiver

Within the PROBA-2 microsatellite mission, a miniaturized single-frequency GPS receiver based on commercial-off-the-shelf (COTS) technology is employed for onboard navigation and timing. A rapid electronic fuse protects against destructive single-event latch-ups (SEL) and enables a quasi-continuous receiver operation despite the inherent sensitivity to space radiation. While limited to single-frequency C/A-code tracking with a narrow-band frontend, the receiver is able to provide precision navigation services through processing of raw GPS measurements on ground as well as a built-in real-time navigation system. In both cases, ionospheric path delays are eliminated through a combination of L1 pseudorange and carrier phase measurements, which also offers a factor-of-two noise reduction relative to code-only processing. By comparison with satellite laser ranging (SLR) measurements, a 0.3-m (3D rms) accuracy is demonstrated for the PROBA-2 reduced dynamic orbit determinations using post-processed GPS orbit and clock products. Furthermore, the experimental onboard navigation system is shown to provide real-time position information with a 3D rms accuracy of about 1?m, which notably outperforms the specification of the Standard Positioning Service (SPS). In view of their lower hardware complexity, mass budget and power requirements as well as the reduced interference susceptibility, legacy C/A-code receivers can thus provide an attractive alternative to dual-frequency receivers even for demanding navigation applications in low Earth orbit.