Keck Spectroscopy of Faint 3 < z < 7 Lyman Break Galaxies: III. The Mean Ultraviolet Spectrum at z=4

We present and discuss the mean rest-frame ultraviolet spectrum for a sample of 81 Lyman Break Galaxies (LBGs) selected to be B-band dropouts with a mean redshift of z=3.9 and apparent magnitudes z_AB<26. Most of the individual spectra are drawn from our ongoing survey in the GOODS fields with the Keck DEIMOS spectrograph, and we have augmented our sample with published data taken with FORS2 on the VLT. In general we find similar trends in the spectral diagnostics to those found in the earlier, more extensive survey of LBGs at z=3 undertaken by Shapley et al (2003). Specifically, we find low-ionization absorption lines which trace the presence of neutral outflowing gas are weaker in galaxies with stronger Lyman-alpha emission, bluer UV spectral slopes, lower stellar masses, lower UV luminosities and smaller half-light radii. This is consistent with a physical picture whereby star formation drives outflows of neutral gas which scatters Lyman-alpha and gives rise to strong low-ionization absorption lines, while increasing the stellar mass, size, metallicity, and dust content of galaxies. Typical galaxies are thus expected to have stronger Lyman-alpha emission and weaker low-ionization absorption at earlier times (higher redshifts). Indeed, our mean spectrum at z=4 shows somewhat weaker low-ionization absorption lines than at z=3 and available data at higher redshift indicates a rapid decrease in low-ionization absorption strength with redshift. We argue that the reduced low-ionization absorption is likely caused by a decrease in the covering fraction and/or velocity range of outflowing neutral gas at earlier epochs. Our continuing survey will enable us to extend these diagnostics more reliably to higher redshift and determine the implications for the escape fraction of ionizing photons which governs the role of early galaxies in cosmic reionization. [Abridged]Comment: 17 pages, 12 figures, submitted to ApJ. Comments welcom

An Assessment of the Air Force Weather Agency\u27s Readiness for Knowledge Management Initiatives

The successful implementation of knowledge management (KM) initiatives requires a level of commitment and preparedness by the organization that is commensurate with the expected results. An organization must be willing to allocate the necessary resources to ensure their readiness to undertake new KM projects. The purpose of this study is to review AFWA’s organizational culture and measure its propensity for accepting KM initiatives. The study uses empirically validated constructs to evaluate and assess the organization’s people, culture, climate, processes and attitudes as they relate to KM. This research was conducted using semi-structured interviews to elicit respondents’ views about KM practices. The data points toward a strong corollary relationship between the organizational environment and its readiness to embrace KM principles

Ampelopsis brevipedunculata (Maxim.) Trautv.

https://thekeep.eiu.edu/herbarium_specimens_byname/13216/thumbnail.jp

Vitis aestivalis F.Michx.

https://thekeep.eiu.edu/herbarium_specimens_byname/19458/thumbnail.jp

Vitis aestivalis F.Michx.

https://thekeep.eiu.edu/herbarium_specimens_byname/19458/thumbnail.jp

A study to assess the aesthetic and economic viability of producing original fine art prints and autographic artists books on a rotary offset press, and an introduction to a new medium for creating and producing original fine art prints and autographic artists books

This study investigates factors which the author believes could contribute to the determination of the aesthetic and economic viability of producing original fine art prints and artists books on a rotary offset press using direct imaged, uncoated lithographic plates. It also introduces a new medium for the creation and production of these works which was developed during this study. This investigation has been accomplished in the following ways: First, answers were sought to ten questions the author believed any artist considering the use of a rotary offset press as a means of producing these works would want to know. The answers were obtained through direct experimentation with a variety of plates which were processed by different procedures and then printed on a rotary offset press. The author concludes on the basis of this experimentation that when the artist\u27s intentions for a specific work coincide with the capabilities of this production process as described in the answers, then this process can be considered aesthetically viable. Second, five-hundred copies of a sixteen page artists book were produced by the author to determine the aesthetic and economic viability of this production process for a specific work. The results indicated that a substantial saving in labor, time, and expense was obtained when this process was employed. There were also substantial savings to the integrity of the work. The author concludes that this process is aesthetically and economically viable for the production of this type of artists book. Third, a survey of commercial printers was undertaken to determine the aesthetic and economic viability of this process in cases where the artist does not have access to a suitable offset press. All the people interviewed indicated that their firms would be willing to accept for production plates imaged and processed by the artists. They also indicated that they would be willing to meet the artist \u27s specifications for the work when these were obtainable, and that the total cost would be based principally on the hourly rate for the specific press being used. On the basis of these and other results of this survey, the author concludes that the production of original fine art prints and artists books by commercial lithographers can be aesthetically and economically viable for the production of certain works. Fourth, people professionally involved in the creation, printing, publishing, selling and collecting of these works were surveyed to assess their usage, awareness, and attitudes regarding their offset press production. The response data to one question in the survey allowed calculations to be made of the acceptability of this process to the total population of the types of people surveyed. As a result of these calculations, conclusions were made that seventy-six percent believe this process is acceptable for the production of original fine art prints. Similarly, one-hundred percent believe it is acceptable for the production of artists books. And fifth, the origins, principles, processing procedures, advantages, and disadvantages of a new medium for the creation and production of original prints and artists books are presented. This medium utilizes direct imaging techniques and light sensitive coated lithographic plates. It is presented for the first time in this study. Any artist wishing to learn about this new medium and any artist considering rotary offset production of original fine art prints or artists books, will find much useful in formation in this study. A portfolio of thirty prints accompanies this study to provide the reader with a firsthand view of the results of the experimentation

ECONOMIC IMPACTS OF LAND USE CHANGES FROM A RESTRICTED NITROGEN FERTILIZER STRATEGY

Land Economics/Use,

Color-octet scalars at the LHC

Color-octet scalars, if present at the TeV scale, will be produced in abundance at the LHC. We discuss in some detail the phenomenology of scalars in the (8,2)_{1/2} representation, recently identified by Manohar and Wise as an addition to the standard-model Higgs sector consistent with the principle of minimal flavor violation. Couplings of this multiplet to the Higgs lift the mass degeneracy among its states, possibly allowing for two-body decays of a heavier colored scalar to a lighter one and a gauge boson. We perform a renormalization group analysis of these couplings and find that limits from Tevatron searches leave little room for these decays. This fact, and the assumption of minimal flavor violation, lead us to study the case where the octets decay to the heaviest kinematically accessible fermion pairs. Focusing on pair-production events leading to (t t-bar t t-bar), (b b-bar b b-bar), and (b b-bar t t-bar) final states, we find that discovery at the LHC should be possible up to masses exceeding 1 TeV.Comment: 15 pages, 6 figues; corrected typos and added discussion of decays to b b-ba

Structure and correlates of cognitive aging in a narrow age cohort

Aging-related changes occur for multiple domains of cognitive functioning. An accumulating body of research indicates that, rather than representing statistically independent phenomena, aging-related cognitive changes are moderately to strongly correlated across domains. However, previous studies have typically been conducted in age-heterogeneous samples over longitudinal time lags of 6 or more years, and have failed to consider whether results are robust to a comprehensive set of controls. Capitalizing on 3-year longitudinal data from the Lothian Birth Cohort of 1936, we took a longitudinal narrow age cohort approach to examine cross-domain cognitive change interrelations from ages 70 to 73 years. We fit multivariate latent difference score models to factors representing visuospatial ability, processing speed, memory, and crystallized ability. Changes were moderately interrelated, with a general factor of change accounting for 47% of the variance in changes across domains. Change interrelations persisted at close to full strength after controlling for a comprehensive set of demographic, physical, and medical factors including educational attainment, childhood intelligence, physical function, APOE genotype, smoking status, diagnosis of hypertension, diagnosis of cardiovascular disease, and diagnosis of diabetes. Thus, the positive manifold of aging-related cognitive changes is highly robust in that it can be detected in a narrow age cohort followed over a relatively brief longitudinal period, and persists even after controlling for many potential confounders