The Ecological Relations of Roots

Although considerable progress has been made in the study of root systems of desert plants (Cannon, 1911, 1913; Markle, 1917), very little information is available concerning the roots of other native species. During 1914 the writer investigated the root systems of the prairie plants of southeastern Washington, where the annual precipitation is only 21.6 inches and occurs mostly in the period of rest: Since that time it has been planned to make a comparative study of the roots of prairie plants growing in a more humid region and where the precipitation occurs mostly during the season of plant growth. The opportunity for such study came during the fall of 1917 and work was carried on vigorously until the soil b~came frozen in December. The study was resumed early in the following spring. In June 1918 the field of investigation was extended to the Great Plains and sandhill region of Coloraoo, while later in the summer a large number of plants were excavated and examined in various habitats about Pike\u27s Peak in the Rocky Mountains. A knowledge of root distribution and root competition under different natural conditions is not only of much scientific value, but it also finds practical application in a better understanding of the value of plants as indicators for distinguishing lands of grazing value only from those with possibilities of crop production. It will result in a more intelligent solution of the ecological probleins of grazing and will likewise be of great aid to the forester in selecting sites for afforestation. Moreover, a knowledge of root distribution will throw a flood of light upon many of. the problems of plant succession. Indeed, the phenomena of ecesis, competition, and reaction can not be completely, if indeed correctly, interpreted without a knowledge of the extent, position, and relation of the root systems of the plants. Shantz has given us an excellent example of the value of a knowledge of root distribution in his study of the natural vegetation of the Great Plains as an indicator of the capabilities of land for crop production (1911). Sampson (1914, 1917) has made a study of root systems of many range plants in considering their life history, forage value, and the natural revegetation of range lands; while foresters are just beginning to study the roots of plants as indicators of conditions of soil moisture on various sites (Korstian, 1917). This paper contains descriptions of the character, depth, and distribution of the roots of about 140 species of plants. These include shrubs, grasses, and other herbs, a few of the latter being noxious weeds. It represents the results of the examination of approximately 1,150 individual plants in 8 different communities, as follows: prairies of eastern Nebraska, chaparral of southeastern Nebraska, prairies of southeastern Washington and adjacent Idaho, plains and sandhills of Colorado, the gravel-slide, the half-gravel-slide, and forest communities of the Rocky Mountains of Colorado. 171 page

RECOVERY OF MIDWESTERN PRAIRIES FROM DROUGHT

The long period of desiccation, which began in 1934, finally terminated in 1940. The western portion of True Prairie was greatly decimated and a veritable mosaic of types of vegetation resulted. These ranged from well-preserved relict communities of bluestems (Andropogon) to mixed stands of grasses on nearly bared soil, but included communities of western wheat grass (Agropyron smithii) , short grasses (Bouteloua gracilis and Buchloe dactyloides) , needle grass (Stipa spartea), and prairie drop seed (Sporobolus heterolepis) . These types varied in size from a few square rods to many acres (fig. 1). One 15- acre prairie, which was mapped in detail, revealed five types, each of which was dominated by a single species, and eight mixed types where two species in each were in definite control. Some of these types of vegetation, moreover, recurred in several parts of this prairie. Over the entire western margin of True Prairie, wide areas of soil were often still open to invaders in 1940 and others were populated only thinly by individuals of a potential grassland type. Even the vegetation in relict communities had usually been greatly thinned by the drought, and dynamic development involved in mutual invasions, competition, and reaction was pronounced (fig. 2). In this process of revegetation western wheat grass played an important part

INDOT Asset Management in 2016

One of INDOT’s performance goals for 2015–2016 is to “take care of what we have.” With that goal in mind, INDOT has been working with staff to implement a plan that maintains steady improvement in pavement and bridge quality and to ensure a commitment to safety, which we will outline in this session

Alignment verification for electron beam lithography

Alignment between lithography layers is essential for device fabrication. A minor defect in a single marker can lead to incorrect alignment and this can be the source of wafer reworks. In this paper we show that this can be prevented by using extra alignment markers to check the alignment during patterning, rather than inspecting vernier patterns after the exposure is completed. Accurate vernier patterns can often only be read after pattern transfer has been carried out. We also show that by using a Penrose tile as a marker it is possible to locate the marker to about 1 nm without fully exposing the resist. This means that the marker can be reused with full accuracy, thus improving the layer to layer alignment accuracy. Lithography tool noise limits the process

UNCOVER: The Growth of the First Massive Black Holes from JWST/NIRSpec—Spectroscopic Redshift Confirmation of an X-Ray Luminous AGN at z = 10.1

The James Webb Space Telescope is now detecting early black holes (BHs) as they transition from seeds to supermassive BHs. Recently, Bogdan et al. reported the detection of an X-ray luminous supermassive BH, UHZ-1, with a photometric redshift at z \u3e 10. Such an extreme source at this very high redshift provides new insights on seeding and growth models for BHs given the short time available for formation and growth. Harnessing the exquisite sensitivity of JWST/NIRSpec, here we report the spectroscopic confirmation of UHZ-1 at z = 10.073 ± 0.002. We find that the NIRSpec/Prism spectrum is typical of recently discovered z ≈ 10 galaxies, characterized primarily by star formation features. We see no clear evidence of the powerful X-ray source in the rest-frame UV/optical spectrum, which may suggest heavy obscuration of the central BH, in line with the Compton-thick column density measured in the X-rays. We perform a stellar population fit simultaneously to the new NIRSpec spectroscopy and previously available photometry. The fit yields a stellar-mass estimate for the host galaxy that is significantly better constrained than prior photometric estimates (�⋆∼1.4−0.4+0.3×108M⊙). Given the predicted BH mass (MBH ∼ 107–108M⊙), the resulting ratio of MBH/M⋆ remains 2 to 3 orders of magnitude higher than local values, thus lending support to the heavy seeding channel for the formation of supermassive BHs within the first billion years of cosmic evolution

UNCOVER: Illuminating the Early Universe—JWST/NIRSpec Confirmation of z \u3e 12 Galaxies

Observations of high-redshift galaxies provide a critical direct test to the theories of early galaxy formation, yet to date, only three have been spectroscopically confirmed at z \u3e 12. Due to strong gravitational lensing over a wide area, the galaxy cluster field A2744 is ideal for searching for the earliest galaxies. Here we present JWST/NIRSpec observations of two galaxies: a robust detection at zspec 12.393 0.001 0.004 = - + , and a plausible candidate at zspec 13.079 0.001 0.013 = - + . The galaxies are discovered in JWST/NIRCam imaging and their distances are inferred with JWST/NIRSpec spectroscopy, all from the JWST Cycle 1 UNCOVER Treasury survey. Detailed stellar population modeling using JWST NIRCam and NIRSpec data corroborates the primeval characteristics of these galaxies: low mass (∼108 Me), young, rapidly assembling, metal-poor, and star-forming. Interestingly, both galaxies are spatially resolved, having lensing-corrected rest-UV effective radii on the order of 300–400 pc, which are notably larger than other spectroscopically confirmed systems at similar redshifts. The observed dynamic range of z 10 sizes spans over 1 order of magnitude, implying a significant scatter in the size–mass relation at early times. Deep into the epoch of reionization, these discoveries elucidate the emergence of the first galaxies

UNCOVER Spectroscopy Confirms the Surprising Ubiquity of Active Galactic Nuclei in Red Sources at z \u3e 5

The James Webb Space Telescope is revealing a new population of dust-reddened broad-line active galactic nuclei (AGN) at redshifts z ≳ 5. Here we present deep NIRSpec/Prism spectroscopy from the Cycle 1 Treasury program Ultradeep NIRSpec and NIRCam ObserVations before the Epoch of Reionization (UNCOVER) of 15 AGN candidates selected to be compact, with red continua in the rest-frame optical but with blue slopes in the UV. From NIRCam photometry alone, they could have been dominated by dusty star formation or an AGN. Here we show that the majority of the compact red sources in UNCOVER are dust-reddened AGN: 60% show definitive evidence for broad-line Hα with a FWHM \u3e 2000 km s −1, 20% of the current data are inconclusive, and 20% are brown dwarf stars. We propose an updated photometric criterion to select red z \u3e 5 AGN that excludes brown dwarfs and is expected to yield \u3e80% AGN. Remarkably, among all zphot \u3e 5 galaxies with F277W – F444W \u3e 1 in UNCOVER at least 33% are AGN regardless of compactness, climbing to at least 80% AGN for sources with F277W – F444W \u3e 1.6. The confirmed AGN have black hole masses of 107–109M⊙. While their UV luminosities (−16 \u3e MUV \u3e −20 AB mag) are low compared to UV-selected AGN at these epochs, consistent with percent-level scattered AGN light or low levels of unobscured star formation, the inferred bolometric luminosities are typical of 107–109M⊙ black holes radiating at ∼10%–40% the Eddington limit. The number densities are surprisingly high at ∼10−5 Mpc−3 mag−1, 100 times more common than the faintest UV-selected quasars, while accounting for ∼1% of the UV-selected galaxies. While their UV faintness suggests they may not contribute strongly to reionization, their ubiquity poses challenges to models of black hole growth

Assessing the Likelihood of Rare Medical Events in Astronauts

Despite over half a century of manned space flight, the space flight community is only now coming to fully assess the short and long term medical dangers of exposure to reduced gravity environments. Further, as new manned spacecraft are designed and with the advent of commercial flight capabilities to the general public, a full understanding of medical risk becomes even more critical for maintaining and understanding mission safety and crew health. To address these critical issues, the National Aeronautics and Space Administration (NASA) Human Research Program (HRP) has begun to address the medical hazards with a formalized risk management approach by effectively identifying and attempting to mitigate acute and chronic medical risks to manned space flight. This paper describes NASA Glenn Research Center?s (GRC) efforts to develop a systematic methodology to assess the likelihood of in-flight medical conditions. Using a probabilistic approach, medical risks are assessed using well established and accepted biomedical and human performance models in combination with fundamentally observed data that defines the astronauts? physical conditions, environment and activity levels. Two different examples of space flight risk are used to show the versatility of our approach and how it successfully integrates disparate information to provide HRP decision makers with a valuable source of information which is otherwise lacking