Geomorphic evidence for ancient seas on Mars

Geomorphic evidence is presented for ancient seas on Mars. Several features, similar to terrestrial lacustrine and coastal features, were identified along the northern plains periphery from Viking images. The nature of these features argues for formation in a predominantly liquid, shallow body of standing water. Such a shallow sea would require either relatively rapid development of shoreline morphologies or a warmer than present climate at the time of outflow channel formation

Geomorphic evidence for ancient seas in west Deuteronilus Mensae, Mars-1: Regional geomorphology

The fretted terrain in west Deuteronilus Mensae consists of extensive cratered upland penninsulas or isolated plateaus cut by long, finger-like canyons typically 10 to 20 km wide and upwards of 300 km long. The longest of these canyons trend roughly north-south to north-northeast, which may reflect some local structural and/or topographic control. At least three geomorphic zones roughly parallel to the lowland/upland boundary, suggestive of increasing modification northward, can be recognized on the fretted region of the region. The southern-most zone (zone A) consists of sharply defined fretted terrain. The middle zone (zone B) consists of well defined fretted terrain in which the plateau surfaces appear smoother, with a somewhat darker and much less varied albedo surface than those of zone A. The northern-most zone (zone C) consists of rounded or softened fretted terrain. The zones were interpreted as surface exposures of successively lower stratigraphic units

Curvilinear ridges and related features in southwest Cydonia Mensae, Mars

Examined is a region on Mars in southwest Cydonia Mensae (32 deg lat., 17 deg long.) just northwest of the lowland/upland boundary escarpment. The dominant morphological features in this region are the clusters of large massifs and plateau outliers (PI), knobby material (K), and smooth lowland plains (Ps). Surrounding the clusters and linking many isolated knobs is a system of curvilinear ridges and arcuate terrain boundaries which tend to separate the massifs and knobs from the smooth plains. Curvilinear ridges are arcuate to nearly linear and smoother in plan than wrinkle ridges and show no apparent correlation with regional structural grain. They are typically 5 to 10 km long but can range from as little as 2 or 3 km to greater than 50 km long. The widths vary from about 100 m to as much as 2 km. Curvilinear ridges are most numerous within 100 km of the lowland/upland boundary escarpment and are associated with massifs and knobby terrain. Arcuate terrain boundaries appear between units of different apparent albedo or arcuate breaks in slope

Geomorphic evidence for ancient seas in west Deuteronilus Mensae, Mars-2: From very high resolution Viking Orbiter images

Very high resolution Viking Orbiter images of the Martian surface, though rare, make it possible to examine specific areas at image scales approaching those of high altitude terrestrial aerial photographs. Twenty three clear images lie within west Deuteronilus Mensae. The northernmost images which constitute an almost unbroken mosaic of the west wall of a long fingerlike canyon are examined. Morphological details on the plateau surface within zone B, not detectable at low resolution, make it possible to divide the zone into two distinct subzones separated by an east-west escarpment. The morphology of the canyon floor is described in detail

Adapted digital music players for individuals with severe impairments

This is the peer reviewed version of the following article: Saunders, M. D., Questad, K. A., Cullinan, T. B., & Saunders, R. R. (2011). Adapted Digital Music Players for Individuals with Severe Impairments. Behavioral Interventions : Theory & Practice in Residential & Community-Based Clinical Programs, 26(2), 10.1002/bin.327. http://doi.org/10.1002/bin.327, which has been published in final form at doi.org/10.1002/bin.327. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-ArchivingPortable music production devices, such as radios, cassette players and MP3 players have characteristics that make them less than ideal for teaching the cause-and-effect relationships that would enable children and adults with severe impairments to control them independently and appropriately. Even when adapted for control with adaptive switches, the relationship between switch closure and on-off operation results in contingency characteristics that can inhibit learning. Some solutions to these problems are described, and for those individuals who can learn with complex contingencies, some promising products are reviewed

Ovid the Christian

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When it Pays to Rush: Interpreting Morphogen Gradients Prior to Steady-State

During development, morphogen gradients precisely determine the position of gene expression boundaries despite the inevitable presence of fluctuations. Recent experiments suggest that some morphogen gradients may be interpreted prior to reaching steady-state. Theoretical work has predicted that such systems will be more robust to embryo-to-embryo fluctuations. By analysing two experimentally motivated models of morphogen gradient formation, we investigate the positional precision of gene expression boundaries determined by pre-steady-state morphogen gradients in the presence of embryo-to-embryo fluctuations, internal biochemical noise and variations in the timing of morphogen measurement. Morphogens that are direct transcription factors are found to be particularly sensitive to internal noise when interpreted prior to steady-state, disadvantaging early measurement, even in the presence of large embryo-to-embryo fluctuations. Morphogens interpreted by cell-surface receptors can be measured prior to steady-state without significant decrease in positional precision provided fluctuations in the timing of measurement are small. Applying our results to experiment, we predict that Bicoid, a transcription factor morphogen in Drosophila, is unlikely to be interpreted prior to reaching steady-state. We also predict that Activin in Xenopus and Nodal in zebrafish, morphogens interpreted by cell-surface receptors, can be decoded in pre-steady-state.Comment: 18 pages, 3 figure

Elder poverty in an ageing world: Conditions of social vulnerability and low income for women in rich and middle-income nations

Social vulnerability for older persons, especially older women, due to insufficient income in retirement and earlier in life and low market earnings may be attributable to many sources, both demographic and economic, in our globalizing world. This paper examines the problems of population ageing, low incomes, and social spending on the elderly in comparative perspective, with a focus on older women in several rich and middle-income nations. We examine the United States, Canada, and a set of European nations using the LIS (Luxembourg Income Study) database, and three middle-income nations, focusing on Taiwan, China, and Mexico, around the turn of the century. In particular, we address what happens to older women as they outlive their husbands and have fewer claims on pensions and retirement wealth and maintain fewer productive capacities in the paid labor force. Issues that arise include the implications of policies relating to taxation, social spending, and transfers, as well as - of course - gender differentials in labor force participation, lifetime savings, and pre- and post-retirement incomes. Many older women, especially those in middle-income countries, also often share living arrangements with their adult children. We assess the net effects of existing policies on poverty and low income and wealth. While best practices may be identified, each nation must create its own set of mutually supportive policies that provide protection against global economic forces while at the same time encouraging self-reliance and efficient behavior, especially in the savings market. We conclude that policy can make a difference in outcomes, as shown for instance by the low cost but highly target effective Canadian efforts in fighting elder poverty, and by the Australian superannuation retirement income system. However, the developing economies of Mexico, China, and even Taiwan evolve from a tradition that does not yet support Western-style social insurance programs. In these nations, intergenerational co-residence is liable to be the key feature of antipoverty policy for elders in the coming decades

Monitoring the Penobscot River Restoration Project: Baseline Data to Inform Ecosystem Response

Dam removal is increasingly being used as a tool to restore aquatic habitats and recover imperiled species. However, many presumed effects of dam removal (i.e. fish community changes, water quality improvements) are largely un-documented. Given significant investments being made in dam removal, rigorous monitoring is needed to elucidate ecological impacts and allow for informed decision making when allocating restoration resources. The Penobscot River Restoration Project in Maine, USA, is an innovative restoration project aimed at restoring self-sustaining populations of diadromous fish through increased connectivity via dam removals and fish passage improvements, while maintaining hydropower output. Beginning prior to dam removal in 2009, independent researchers began documenting baseline conditions via a multi-disciplinary, coordinated monitoring framework. The framework has continued through project implementation, following a before-after study design. Monitoring focuses on geomorphology, water quality, fish community, fish passage, habitat use, shoreline revegetation and marine-freshwater nutrient transfers. As before-after comparative analyses continue to unfold, this presentation aims to provide the most current results of this monitoring effort, highlighting several patterns which have emerged to-date: 1) all native diadromous species of fish are present in the river, many successfully reproducing on their own; 2) diadromous species persist despite access to only a small percentage of their historic habitat, many now beginning to increase in number; 3) the former lowermost dam, represented a near complete barrier to migration for most species and is now traversed by many similarly to free-flowing sections; 4) large changes to flow, sediment regime, and habitat (except in the immediate vicinity of the former dam sites) were unexpected and did not occur; and 5) water quality did not appear to be limiting for most species. This effort provides an objective, credible basis for evaluating ecosystem response to dam removal and a knowledge base to support restoration approaches in other systems