Bulletin No. 324 - Some Physical and Chemical Responses of Agropyron Spicatum to Herbage Removal at Various Seasons

Management of arid western ranges must be based upon the physiology of the individual plants which constitute the range. Too little is known of the ability of range plants to continue normal functioning under stress of grazing. Grazing doubtless has some beneficial influences in arid climates because it reduces transpiring surface. Possibly pruning has some stimulating effect, especially upon shrubs, and also, grazing animals plant seeds through trampling action. Despite these possible benefits, both trampling and removal of herbage by grazing must be .regarded as fundamentally detrimental to the welfare of plants, especially in arid climates. Trampling, especially on wet soils during early spring months, is injurious to both mature plants and new seedlings; however, in general, removal of herbage is probably far more injurious. Ability of the individual plant to withstand herbage removal appears to be basically important in range conservation. Studying effect of grazing by artificial means, such as clipping the herbage with shears, has been criticised, yet it seems the most sound method of studying forage plant physiology, since clipping permits accurate measurement of herbage yield. The experiment reported herein was designed to test the basic response of a single grass species to herbage removal at various seasons as measured by forage production and chemical composition

Population Biology of the Black-tailed Jackrabbit (Lepus californicus) in Northern Utah

Population biology of the black-tailed jackrabbit population on a 250-square-mile area in Curlew Valley, northern Utah, was studied from 1962-70. During this period the fall population density index increased from 40.0 in 1962, to 60.6 in 1963, decreased progressively to a low of 21.2 in 1967, then increased the following 3 years to a high of 185.0 in 1970. Breeding was synchronous with four conception periods each year; in some years a fifth conception period was evident. The first conception period occurred about the last half of January; other periods followed at 40-day intervals indicating a 40-day gestation period and postpartum estrus with subsequent conception. Over the 9 years of study, the mean percentages of females breeding during the five conception periods were 88, 99, 100, 70, and 11 percent, respectively. The mean number of ova ovulated per breeding female for the five periods was 1.9, 5.1, 6.4, 4.9, and 3.6, respectively. During the period of decreasing density, 1963-67, the yearly mean number of ova ovulated per female surviving the breeding season ranged from 13.2-19.3, but varied independently of density. During the 3 consecutive years of density increase, 1968-70, however, the number of ova ovulated per female decreased progressively from 19.8 in 1968 to 14.2 in 1970. Mortality rates of the total population from October-March remained relatively constant (mean: 63 percent) during the years of population decline, but dropped to 33 percent during the first year of population increase (1968). March-October mortality of adults decreased to 9 percent during the first year of population increase from a previous mean of 73 percent, and juvenile mortality from parturition to fall census, decreased from a mean of 68 percent to 38 percent. The effects of variations in mortality rates on population density have overshadowed the effects of the relatively less extreme variations in natality rates. As a result the pattern of density change was almost entirely a result of changes in mortality rates. Changes in mortality rates of adults and juveniles were well correlated with the coyote/rabbit ratio on the study area. Exceptions occurred with juvenile mortality rates at the relatively high rabbit densities observed in 1969-70. During these two years, juvenile mortality rates from parturition to fall census (61 and 68 percent, respectively) were greater than could be accounted for by coyote predation. The factor or factors responsible for the increased juvenile mortality are not known. Observed annual density changes were described with the mathematical model: Nt+4 = Nt (1 - 37.8 - 988x1) (1 + 11.2 - 1130x2 - 0.0581x3 + 42000x22 + 0.00115x32) where Nt is the number of animals at the end of October, Nt+1 is the number of animals at the end of the following October, x1 is the coyote/rabbit ratio from October-March, x2 is the coyote/rabbit ratio from March-October, and x3 is the mean number of rabbits per square mile from March-October. The model accounts for 99 percent of the observed change in rabbit density from 1968-70

Bulletin No. 305 - The Composition of Sumer Range Plants in Utah

In Utah, a vast industry of livestock grazing, which is the backbone of the state\u27s agriculture, has arisen during the past 75 years. Range land furnishes between 6 and 7 million animal unit months of forage to some 2 1/2 million sheep and 275 thousand range cattle. Income from meat, wool, and range livestock sales in Utah is about $15,801,500 annually, of which$11,700,000 is calculated to be obtained from range lands exclusive of cultivated pastures. These range lands can be used economically in no other way than by grazing livestock and, because of heavy winter snows and protracted dry periods, most of these lands are distinctly seasonal in character. Livestock, then, must be supported for Iong periods upon farm lands or upon other range lands. The animals must be driven or shipped over distances sometimes well in excess of 100 miles from one range to another. The specific seasonal nature of these lands makes important the study of seasonal variations in forage value. That animals can make the most efficient use of the range lands, it is important to understand the forage value, the balance of various chemical constituents, and the importance of deficiencies in the diet of animals existing wholly upon these native plants

Bulletin No. 364 - The Halogeton Problem in Utah

Halogeton (Halogeton glomeratus) although introduced into Utah only 20 years ago, has spread widely on the west desert and into extensive areas on the east desert. This plant has become the most feared poisonous plant in the state because people have been lead to believe that it would limit livestock production to areas kept free of the weed

Bulletin No. 372 - The Nutritive Value of Winter Range Plants in the Great Basin as Determined with Digestion Trials with Sheep

During the winter grazing seasons from 1946 to 1953, studies were carried on throughout the desert ranges of western Utah to determine nutritive content and digestibility of range forage plants. These desert areas receive about 7 inches of precipitation annually and the vegetation consists, chiefly, of saltbush and sagebrush types. The average floral composition of the desert areas studied was about 74 percent browse, 25 percent grass, and 1 percent forbs. However, on some areas there was more grass than browse and, on still others, large quantities of forbs were present, primarily Russian-thistle. Digestion trials were carried out under normal range conditions by the use of the lignin-ratio method. Desert ranges in winter were found to be from borderline to decidedly deficient in digestible protein, phosphorus, and metabolizable energy. Diets containing appreciable quantity of browse furnished more than 10 times the minimum requirement of carotene, whereas, grass ranges were decidedly deficient in this respect

T-DominO: Exploring Multiple Criteria with Quality-Diversity and the Tournament Dominance Objective

Real-world design problems are a messy combination of constraints, objectives, and features. Exploring these problem spaces can be defined as a Multi-Criteria Exploration (MCX) problem, whose goals are to produce a set of diverse solutions with high performance across many objectives, while avoiding low performance across any objectives. Quality-Diversity algorithms produce the needed design variation, but typically consider only a single objective. We present a new ranking, T-DominO, specifically designed to handle multiple objectives in MCX problems. T-DominO ranks individuals relative to other solutions in the archive, favoring individuals with balanced performance over those which excel at a few objectives at the cost of the others. Keeping only a single balanced solution in each MAP-Elites bin maintains the visual accessibility of the archive – a strong asset for design exploration. We illustrate our approach on a set of easily understood benchmarks, and showcase its potential in a many-objective real-world architecture case study

Bulletin No. 385 - Comparitive Nutritive Value and Palatability of Some Introduced and Native Forage Plants for Spring and Summer Grazing

From 1952 to 1954 studies were conducted on foothill ranges of central Utah to determine the forage production, palatability, and nutritive value of some of the more important native and introduced species used for spring and summer grazing. Plants studied were four introduced wheatgrasses (crested, tall, pubescent, and intermediate) , four native grasses (western wheatgrass, beardless wheatgrass, squirreltail grass, and Indian ricegrass), and two introduced annual forbs (Russian-thistle, and smother weed). Field digestibility trials were conducted to determine the nutrient content by the lignin-ratio technique. In addition, both sheep and cattle preferences were studied on areas where both introduced and native species were planted

The Impact of a GED to College Transitions Program on Student Motivation

Student‘s motivation and persistence are common issues that educators and learners struggle with continuously. This is particularly significant in the field of adult education. According to Hardin (2008) these adult learners, or non-traditional students exhibit characteristics such as; delaying enrollment into higher education until adulthood, enrolling part time, working full time, being financially independent, has family responsibilities and academic deficiencies. Such characteristics can form severe barriers in the quest to pursue higher education. Therefore, understanding self-determination and motivation are necessary to help these learners to be successful. To help students to be successful, scholars and practitioners must engage in longitudinal studies in order to help students transition from General Education Diploma (GED) and other basic adult education programs to higher education. In this study, the researchers make meaning of the participant‘s experiences that can add data to the current research base. This study is aimed at exploring the experiences of 14 GED students enrolled in a GED to College Transitions course at a southern community college in the US during the spring 2011 semester. The study was guided by the following research question: What primary factors motivate GED students to enroll and persist

A Push-Button Molecular Switch

The preparation, characterization, and switching mechanism of a unique single-station mechanically switchable hetero[2]catenane are reported. The facile synthesis utilizing a “threading-followed-by-clipping” protocol features Cu^(2+)-catalyzed Eglinton coupling as a mild and efficient route to the tetrathiafulvalene-based catenane in high yield. The resulting mechanically interlocked molecule operates as a perfect molecular switch, most readily described as a “push-button” switch, whereby two discrete and fully occupied translational states are toggled electrochemically at incredibly high rates. This mechanical switching was probed using a wide variety of experimental techniques as well as quantum-mechanical investigations. The fundamental distinctions between this single-station [2]catenane and other more traditional bi- and multistation molecular switches are significant

Validation of the SCID-hu Thy/Liv mouse model with four classes of licensed antiretrovirals.

BackgroundThe SCID-hu Thy/Liv mouse model of HIV-1 infection is a useful platform for the preclinical evaluation of antiviral efficacy in vivo. We performed this study to validate the model with representatives of all four classes of licensed antiretrovirals.Methodology/principal findingsEndpoint analyses for quantification of Thy/Liv implant viral load included ELISA for cell-associated p24, branched DNA assay for HIV-1 RNA, and detection of infected thymocytes by intracellular staining for Gag-p24. Antiviral protection from HIV-1-mediated thymocyte depletion was assessed by multicolor flow cytometric analysis of thymocyte subpopulations based on surface expression of CD3, CD4, and CD8. These mice can be productively infected with molecular clones of HIV-1 (e.g., the X4 clone NL4-3) as well as with primary R5 and R5X4 isolates. To determine whether results in this model are concordant with those found in humans, we performed direct comparisons of two drugs in the same class, each of which has known potency and dosing levels in humans. Here we show that second-generation antiretrovirals were, as expected, more potent than their first-generation predecessors: emtricitabine was more potent than lamivudine, efavirenz was more potent than nevirapine, and atazanavir was more potent than indinavir. After interspecies pharmacodynamic scaling, the dose ranges found to inhibit viral replication in the SCID-hu Thy/Liv mouse were similar to those used in humans. Moreover, HIV-1 replication in these mice was genetically stable; treatment of the mice with lamivudine did not result in the M184V substitution in reverse transcriptase, and the multidrug-resistant NY index case HIV-1 retained its drug-resistance substitutions.ConclusionGiven the fidelity of such comparisons, we conclude that this highly reproducible mouse model is likely to predict clinical antiviral efficacy in humans