The Internal Validation of a National Model of Long Distance Traffic.

During 1980/81, the Department of Transport developed a model for describing the distribution of private vehicle trips between 642 districts in Great Britain, using data from household and roadside interviews conducted in 1976 for the Regional Highways Traffic Model, and a new formulation of the gravity model, called a composite approach, in which shorter length movements were described at a finer level of zonal detail than longer movements. This report describes the results of an independent validation exercise conducted for the Department, in which the theoretical basis of the model and its the quality of its fit to base year data were examined. The report discusses model specification; input data; calibration issues; and accuracy assessment. The main problems addressed included the treatment of intrazonal and terminal costs, which was thought to be deficient; the trip-end estimates to which the model was constrained, which were shown to have substantial variability and to be biassed (though the cause of the latter could be readily removed), with some evidence of geographical under-specification; and the differences between roadside and household interview estimates. The report includes a detailed examination of the composite model specification and contains suggestions for improving the way in which such models are fitted. The main technical developments, for both theory and practice, are the methods developed for assessing the accuracy of the fitted model and for examining the quality of its fit with respect to the observed data, taking account of the variances and covariances of modelled and data values. Overall, the broad conclusion was that, whilst there appeared to be broad compatibility between modelled and onserved data in observed cells, there was clear evidence of inadequacy in certain respects, such as for example underestimation of intradistr ict trips. This work was done in co-operation with Howard Humphreys and Partners and Transportation Planning Associates, who validated the model against independent external data; their work is reported separately

Strain transfer and partitioning between the Panamint Valley, Searles Valley, and Ash Hill fault zones, California

We report new geologic and geomorphic observations that bear on the interpretation of connectivity and strain transfer among the Panamint Valley, Searles Valley, and Ash Hill fault zones, southern Walker Lane belt of California. Although these faults partition strain regionally onto dominantly normal and strike-slip structures, strain transfer occurs in a complex way not typical of linked strike-slip and extensional faults. The Searles Valley fault (W-directed normal fault) transfers slip onto the Panamint Valley zone, which changes from dominantly NNW-trending dextral strike-slip to more normal motion where they join. The Ash Hill fault (mostly right-lateral strike slip) transfers strain into the northern continuation of the Searles Valley zone, via a complex array of hanging-wall normal and strike-slip faults. These complex interactions, based on the age of structurally offset markers, appear to be stable over~105 years

Late Pleistocene slip on a low-angle normal fault, Searles Valley, California

The mechanical feasibility of normal-sense slip on low-angle faults remains a conundrum in extensional tectonics. The rarity of demonstrably active low-angle normal faults may imply that very specifi c criteria must be satisfi ed for signifi cant fault displacement. We present new geologic observations, geomorphic mapping, and structural analysis for a low-angle fault zone along the eastern margin of Searles Valley, California. Our observations indicate that Pleistocene displacement along the range-front fault scarps is the near-surface expression of slip on a bedrock-rooted low-angle normal fault. Along the central portion of the range front in Searles Valley, high-angle faults offset late Pleistocene alluvial and lacustrine surfaces. These faults merge downward into a westdipping, low-angle fault, but do not displace the low-angle surface. These geometric relations are satisfi ed only when displacement on the high-angle faults is accommodated by slip on the basal low-angle fault. We use displaced alluvial fan surfaces to determine slip rates across the fault system over late Pleistocene to Holocene time. Combining radiocarbon ages of lacustrine tufa deposits with high-precision topographic surveys of fault scarps yields average slip rates of 0.21- 0.35 m/k.y. Additional mapping of faults within the Slate Range at the northern end of Searles Valley suggests that slip is transferred northward to the Manly Pass fault, a bedrock normal fault that trends northeast into Panamint Valley. Thus, although displacement along the range-front fault system dies out northward, we infer that active deformation occurs within the range and likely links extension in Searles Valley with deformation in Panamint Valley

Pliocene-Pleistocene basin evolution along the Garlock fault zone, Pilot Knob Valley, California

Exposed Pliocene-Pleistocene terrestrial strata provide an archive of the spatial and temporal development of a basin astride the sinistral Garlock fault in California. In the southern Slate Range and Pilot Knob Valley, an ~2000-m-thick package of Late Cenozoic strata has been uplifted and tilted to the northeast. We name this succession the formation of Pilot Knob Valley and provide new chronologic, stratigraphic, and provenance data for these rocks. The unit is divided into five members that record different source areas and depositional patterns: (1) the lowest exposed strata are conglomeratic rocks derived from Miocene Eagle Crags volcanic field to the south and east across the Garlock fault (2) the second member consists mostly of fine-grained rocks with coarser material derived from both southern and northern sources; and (3) the upper three members are primarily coarse-grained conglomerates and sandstones derived from the adjacent Slate Range to the north. Tephrochronologic data from four ash samples bracket deposition of the second member to 3.6-3.3 Ma and the fourth member to between 1.1 and 0.6 Ma. A fifth tephrochronologic sample from rocks south of the Garlock fault near Christmas Canyon brackets deposition of a possible equivalent to the second member of the formation of Pilot Knob Valley at ca. 3.1 Ma. Although the age of the base of the lowest member is not directly dated, regional stratigraphic and tectonic associations suggest that the basin started forming ca. 4-5 Ma. By ca. 3.6 Ma, the northward progradation fanglomerate sourced in the Eagle Crags region waned, and subsequent deposition occurred in shallow lacustrine systems. At ca. 3.3 Ma, southward progradation of conglomerates derived from the Slate Range began. Circa 1.1 Ma, continued southward progradation of fanglomerate with Slate Range sources is characterized by a shift to coarser grain sizes, interpreted to reflect uplift of the Slate Range. Overall, basin architecture and the temporal evolution of different source regions were controlled by activity on three regionally important faults-the Garlock, the Marine Gate, and the Searles Valley faults. The timing and style of motions on these faults appear to be directly linked to patterns of basin development

Water wave propagation and scattering over topographical bottoms

Here I present a general formulation of water wave propagation and scattering over topographical bottoms. A simple equation is found and is compared with existing theories. As an application, the theory is extended to the case of water waves in a column with many cylindrical steps

Temporal variations in Holocene slip rate along the central Garlock fault, Pilot Knob Valley, California

Average geologic slip rates along the central Garlock fault, in eastern California, are thought to have been relatively steady at 5-7 mm/yr since at least the Late Pleistocene, yet present-day rates inferred from geodetic velocity fields are indistinguishable from zero. We evaluate the possibility of non-steady slip over millennial timescales using displaced Late Holocene alluvium along the central Garlock fault in Pilot Knob Valley. Truncation of a Late Holocene alluvial fan deposit against a shutter ridge requires a minimum of 30-37 m of displacement since deposition of the fan; maximum allowable displacement is 43-50 m. The extent of soil development atop the fan surface and optically stimulated luminescence ages bracket fan deposition between 3.5 and 4.5 ka. Together, these data require that slip rates during the Late Holocene were ̃7-14 mm/yr, with a preferred rate of ̃11-13 mm/yr. Our results, in conjunction with previous estimates of displacement over the past ̃15 ka, require significant temporal variations in strain release along the Garlock fault and confirm previous suggestions that interactions among fault systems in eastern California give rise to alternating periods of fault activity and quiescence

Effects of silver sulfide nanomaterials on mycorrhizal colonization of tomato plants and soil microbial communities in biosolid-amended soil

We investigated effects of Ag2S engineered nanomaterials (ENMs), polyvinylpyrrolidone (PVP) coated Ag ENMs (PVP-Ag), and Ag+ on arbuscular mycorrhizal fungi (AMF), their colonization of tomato (Solanum lycopersicum), and overall microbial community structure in biosolids-amended soil. Concentration-dependent uptake was measured in all treatments. Plants exposed to 100 mg kg−1 PVP-Ag ENMs and 100 mg kg−1 Ag+ exhibited reduced biomass and greatly reduced mycorrhizal colonization. Bacteria, actinomycetes and fungi were inhibited by all treatment classes, with the largest reductions measured in 100 mg kg−1 PVP-Ag ENMs and 100 mg kg−1 Ag+. Overall, Ag2S ENMs were less toxic to plants, less disruptive to plant-mycorrhizal symbiosis, and less inhibitory to the soil microbial community than PVP-Ag ENMs or Ag+. However, significant effects were observed at 1 mg kg−1 Ag2S ENMs, suggesting that the potential exists for microbial communities and the ecosystem services they provide to be disrupted by environmentally relevant concentrations of Ag2S ENMs.Jonathan D. Judy, Jason K. Kirby, Courtney Creamer, Mike J. McLaughlin, Cathy Fiebiger, Claire Wright, Timothy R. Cavagnaro, Paul M. Bertsc

Oligodendrocyte pathology exceeds axonal pathology in white matter in human amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease. The majority of cases are sporadic (sALS) while the most common inherited form is due to C9orf72 mutation (C9ALS). A high burden of inclusion pathology is seen in glia (including oligodendrocytes) in ALS, especially in C9ALS. Myelin basic protein (MBP) messenger RNA (mRNA) must be transported to oligodendrocyte processes for myelination, a possible vulnerability for normal function. TDP43 is found in pathological inclusions in ALS and is a component of mRNA transport granules. Thus, TDP43 aggregation could lead to MBP loss. Additionally, the hexanucleotide expansion of mutant C9ALS, binds hnRNPA2/B1, a protein essential for mRNA transport causing potential further impairment of hnRNPA2/B1 function, and thus myelination. Using immunohistochemistry p62 and TDP43 in human post mortem tissue, we found a high burden of glial inclusions in the prefrontal cortex, precentral gyrus and spinal cord in ALS, which was greater in C9ALS than sALS cases. Double staining demonstrated the majority of these inclusions were in oligodendrocytes. Using immunoblotting, we demonstrated reduced MBP protein levels relative to PLP (a myelin component that relies on protein not mRNA transport) and neurofilament protein (an axonal marker) in the spinal cord. This MBP loss was disproportionate to the level of PLP and axonal loss, suggesting that impaired mRNA transport may be partly responsible. Finally, we show that in C9ALS cases, the level of oligodendroglial inclusions correlates inversely with levels of hnRNPA2/B1 and the number of oligodendrocyte precursor cells. We conclude that there is considerable oligodendrocyte pathology in ALS, which at least partially reflects impairment of mRNA transport