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

Renormalization of cavity field theories

Bibliography: pages 95-97.A major obstacle to calculating Feynman diagrams in field theories, confined to a cavity, has always been the divergent loop diagrams. So far, only the quantum chromodynamic and electrodynamic self-energies of a ls1/2 quark, confined to a static spherical cavity, have been accurately calculated. These quantities are of immediate interest in the M.I.T. bag model. The existing methods to calculate loop diagrams are based on the multiple reflection scheme, in which the zero reflection term is separated out analytically, and evaluated separately. Thus far, there are some indications that this method is unsuitable for the quadratically divergent one loop vacuum polarization. In this thesis we firstly develop a set of Fourier transforms, appropriate to a discussion of renormalization in a cavity. Using these, we renormalize the cavity propagators to one loop for scalar, Dirac, and gauge fields. We then introduce a new computational method to subtract out the divergences, based on dimensional regularization. Using this method, we present results for various loop diagrams. The scalar φ⁴ theory is used as a pedagogical example. We then present the quark self-energy for several low lying cavity modes. Finally we tackle the long standing and hitherto unresolved question of the vacuum polarization. For this we give a detailed discussion of surface divergences, and present results for scalar quantum electrodynamics. We make a suggestion for the implementation of the running coupling constant in the cavity

A Community of OER Practice: The Intermountain Open Pedagogy Education Network (iOPEN)

Open Education Resource (OER) work requires an engaged community to be successful. This community can be leveraged to share expertise and experiences that can make local OER efforts more effective and successful. iOPEN started as a series of informal virtual conversations that has evolved into a regional practitioner community that plans OER strategy, advocates for statewide change, shares funding opportunities, and co-presents their research. This poster will share how iOPEN became a community of practice and suggest strategies to create your own OER community of practice

\u3cem\u3eCurrere\u3c/em\u3e as a Method for Critical Reflection in the Profession of Academic Librarianship

Academic librarianship has an intimate association with narratives and stories from their traditional role in curating, caring for, and making collections accessible. Librarians also experience the intricacies and challenges of narrative inquiry through the qualitative research they undertake, oral histories they gather, reflective teaching practices they facilitate, and oral-traditions they interact with. Despite these intersections with reflection and narratives, academic librarianship, and library sciences as a whole, have not fully incorporated their own narratives within their practices. Academic librarianship has the ability but not the spaces to critically reflect in a holistic manner. Shadiow (2013) encourages us all to “recall, retell, and then scrutinize your stories” (p. ix) through critical reflection. One potential method to accomplish this task of “scrutinizing our stories” is the reflective technique known as currere. Grumet (1976a) suggests that currere allows us to put our “essences back into existence” (p. 41). Currere provides a pathway to putting ourselves back into librarianship much as it has done with other educators. This study explores the use of currere with a group of practicing academic librarians by the application of a reflection curriculum over a twelve week period. The central research question of this study seeks to answer is: What does structured, holistic, and critical reflection, such as currere, reveal about librarianship

Range Land of America and Some Research on its Management

Although grazing of livestock has been a practice and a profession of man almost from his beginning only recently has range management reached anything approaching a pre~ cise science. Although \u27 trials and errors over the years brought to light much practical methodology for assuring high production from grazing land, still it remained for the plant physiologist and ecologist to find the whys and wherefores, and to advance new methods and new thoughts which promise to increase productivity still further and at the same time maintain the great range resource. The peculiar land situation that marked America in her forma~ tive years had much to do with the philosophy of early livestock growers. To understand this philosophy, we must remember the free~ dem and the vastness of frontier America. Graziers owned little or no land and their movements were known to few and questioned by none. The plentiful forage is evidenced now by words of early ad~ venturers. as Fremont\u27s ... tremendous areas of luxuriant grass-an inexhaustible supply ; Lewis and Clark\u27s These western ranges have a luxuriant grass cover and will supply enough feed for all the cows in all the world ; and Bradley\u27s .. . good, fine grasses grow evenly all over the country-I believe that all the flocks and herds in the world could find ample pasturage [here]. Herdsmen rested se~ cure in the knowledge that over the next ridge was more feed free to the first comer

Effects of in ovo herbicide exposure in newly hatched domestic chickens (Gallus gallus) and ducks (Anas platyrhynchos)

Agriculture is a valuable economic resource in western Canada, but for decades farmers have focused on intensive production practices while ignoring the long-term health and maintenance of the land. In recent years, the use of conservation agricultural techniques has been encouraged in an effort to conserve prairie landscape while sustaining cropland productivity. Sustainable agricultural practices that promote soil and water conservation and benefit wildlife and prairie biodiversity include conservation tillage and planting of winter cereal crops. Many species of wild birds nest in the ground cover provided by minimum tillage and fall seeded cropland in the spring. Although habitat quality in conservation areas is superior for birds, there is potential for eggs of ground nesting birds to be exposed to herbicides during spring weed control operations. Herbicides commonly used on the prairies to control weed growth in conservational systems include 2,4-D and Buctril-M®. Since the subtlethal effects of exposure to these herbicides may include DNA damage and immunomodulation, the overall goal of this study was to assess whether in ovo exposure to the herbicides 2,4-D and Buctril-M® adversely affects genetic material and/or immune system function in newly hatched domestic chickens (Gallus gallus) and ducks (Anas platyrhynchos), as surrogates for wild bird species.Study design attempted to reproduce actual field exposures by use of an agricultural field spray simulator to apply formulated herbicides (as opposed to pure active ingredients) at recommended crop application rates. In three separate experiments, fertile chicken eggs were sprayed with 2,4-D ester formulation or with Buctril-M® formulation, and fertile duck eggs were sprayed with 2,4-D ester formulation, during either an early (embryonic day 6) or late (embryonic day 15 for chickens or embryonic day 21 for ducks) stage of incubation. Genotoxicity and immune system function were evaluated in the hatchlings as the main toxicological endpoints to assess potential subtle effects from herbicide exposure, but additional measures of general health and development were also evaluated. Two endpoints were used to assess subtle changes to genetic integrity. The comet assay was used to detect structural damage (strand breaks) in avian lymphocyte DNA, as an index of acute genotoxic effects. Flow cytometry was used to examine potential clastogenic effects of the herbicides, by determining if chromosomal changes resulted in variability in the DNA content of avian erythrocytes. Several endpoints were examined to evaluate potential exposure-induced effects on the immune system. Immunopathological assessment of chicks and ducklings included differential lymphocyte counts, as well as immune organ weights and histopathology. The cell-mediated and humoral immune responses in hatchlings were assessed using the delayed-type hypersensitivity test and measurement of systemic antibody production in response to immunization, respectively. Exposure of fertile chicken and duck eggs to Buctril-M® or 2,4-D had no effects on the biomarkers of genetic integrity in this study. Differences in herbicide treatment (high and low concentrations) and times of exposure (early and late incubation stages) did not translate into noticeable factor effects in final model analyses for any of the genotoxicity assay variables evaluated in newly hatched chickens exposed in ovo to 2,4-D. Similarly, comet assay outcomes in chicks exposed to Buctril-M® were not significantly associated with either herbicide treatment or time of exposure as fixed effect factors. Results of the comet assay using peripheral lymphocytes from ducklings provided evidence of potential primary genetic damage associated with the time of spray exposure in ovo. Comet tail DNA content was significantly associated (P = 0.0269) with exposure times, suggesting that ducks may be increasingly sensitive to spray exposure conditions at an early stage of embryological development. Effects of exposure timing were not attributable to herbicide treatment. Although 2,4-D exposure time was associated with DNA strand breakage in ducklings, there was no evidence of chromosomal damage. However, an association between the HPCV values (a measure of DNA content variability) and time of spray exposure was observed in the experiment where 21-day-old chickens were treated in ovo with Buctril-M®. The mean HPCV value for the early exposure group (E6) was significantly greater (P = 0.0210) than that of the group treated later in incubation (E15). However, Buctril-M® the concentration of herbicide did not have any influence on this outcome, and the reason for the difference between exposure times is uncertain, but may be attributed to stress associated with manipulations during spraying. An increase in HPCV, reflecting greater intercellular DNA variability, is indicative of increased incidence of chromosomal damage, which may be an effect of disturbance during early periods of incubation as a result of exposure conditions.Among the panel of immunotoxicity tests conducted to evaluate the effects of in ovo exposure to 2,4-D and Buctril-M® on the developing avian immune system, only heterophil/ lymphocyte (H/L) ratios and relative immune organ weights were significantly associated with either herbicide treatment or time of spray exposure in all three experiments. In 21-day-old chicks exposed in ovo to 2,4-D, relative bursa weight was associated with the different herbicide treatments (P = 0.0006). Relative bursa weights were significantly lower in chicks in the low dose group, while the opposite effect was observed in the high dose chicks, compared with the controls. It is unlikely that the observed decrease in bursa weight in the low dose group is causally related to herbicide exposure because a consistent dose-response effect was not observed, but this outcome may be explained by a compensatory immune response. The relative spleen weights of newly hatched chickens exposed in ovo to Buctril-M® exhibited a significant association with herbicide treatment (P = 0.0137). Relative spleen weights for birds in the low dose treatment groups were significantly different than both the control (P = 0.0179) and high dose groups (P = 0.0125). However, there was no significant difference between high dose and control groups, and this outcome reduces the likelihood of a causal relationship between spleen weight and herbicide exposure. In the parallel experiment involving in ovo exposure to 2,4-D to ducklings, relative bursa weight was associated with time of spray exposure (P = 0.0434). Ducklings that hatched from eggs exposed to spray on day 6 of incubation exhibited greater mean relative bursa weights than the birds exposed to spray at a later incubation stage (E21). This result implies that spray exposure during earlier stages of development may result in conditions which affect the humoral immune response, if increased bursal weight is associated with increased B lymphocyte and antibody production. In the same experiment, mean H/L ratios in peripheral blood samples from 21-day-old ducklings were significantly different between the groups treated with the high concentration of 2,4-D and water (control) (P = 0.0395). Although ratios from the birds in the low dose groups were not significantly different from the control groups, changes in H/L ratio values demonstrate a dose dependent relationship with increasing herbicide exposure.Residue analysis of chicken and duck eggs in this study measured transfer of herbicide through the shell and into the embryo 24 hours and up to 5 days (chickens only) after spraying. Mean 2,4-D residue concentrations were higher in both chicken and duck eggs from the high dose (10X) groups than in eggs exposed to the recommended field rate of herbicide application (1X). Embryo residue concentrations in the chicken eggs increased from the day following exposure to 5 days after spraying, in both low and high dose groups. This observation indicates that the risk of contaminant-induced adverse effects may continue to increase for at least several days after exposure, thereby influencing the concentration of herbicide to which the developing embryo is exposed.On the Canadian prairies, wild bird eggs are potentially to be exposed to 2,4-D and Buctril-M® during various stages of embryonic development. The present study examined effects of herbicide exposure at two distinct times during incubation, and demonstrated the potential for subtle impacts on genetic integrity and the immune system. Results indicate that spray exposure during earlier stages of organogenesis may cause more significant adverse effects. Given the possible harmful consequences of the observed changes on the long-term health of wild birds, further research is needed in order to better characterize the risks of in ovo agrochemical exposure in prairie ecosystems

The clathrin-binding domain of CALM-AF10 alters the phenotype of myeloid neoplasms in mice.

The PICALM (CALM) gene, whose product is involved in clathrin-mediated endocytosis, has been identified in two recurring chromosomal translocations, involving either MLL or MLLT10 (AF10). We developed a mouse model of CALM-AF10(+) leukemia to examine the hypothesis that disruption of endocytosis contributes to leukemogenesis. Exclusion of the C-terminal portion of CALM from the fusion protein, which is required for optimal binding to clathrin, resulted in the development of a myeloproliferative disease, whereas inclusion of this domain led to the development of acute myeloid leukemia and changes in gene expression of several cancer-related genes, notably Pim1 and Crebbp. Nonetheless, the development of leukemia could not be attributed directly to interference with endocytosis or consequential changes in proliferation and signaling. In leukemia cells, full-length CALM-AF10 localized to the nucleus with no consistent effect on growth factor endocyctosis, and suppressed histone H3 lysine 79 methylation regardless of the presence of clathrin. Using fluorescence resonance energy transfer analysis, we show that CALM-AF10 has a propensity to homo-oligomerize, raising the possibility that the function of endocytic proteins involved in chimeric fusions may be to provide dimerization properties, a recognized mechanism for unleashing oncogenic properties of chimeric transcription factors, rather than disrupting the internalization of growth factor receptors

Mechanically bonded macromolecules

Mechanically bonded macromolecules constitute a class of challenging synthetic targets in polymer science. The controllable intramolecular motions of mechanical bonds, in combination with the processability and useful physical and mechanical properties of macromolecules, ultimately ensure their potential for applications in materials science, nanotechnology and medicine. This tutorial review describes the syntheses and properties of a library of diverse mechanically bonded macromolecules, which covers (i) main-chain, side-chain, bridged, and pendant oligo/polycatenanes, (ii) main-chain oligo/polyrotaxanes, (iii) poly[c2]daisy chains, and finally (iv) mechanically interlocked dendrimers. A variety of highly efficient synthetic protocols—including template-directed assembly, step-growth polymerisation, quantitative conjugation, etc.—were employed in the construction of these mechanically interlocked architectures. Some of these structures, i.e., side-chain polycatenanes and poly[c2]daisy chains, undergo controllable molecular switching in a manner similar to their small molecular counterparts. The challenges posed by the syntheses of polycatenanes and polyrotaxanes with high molecular weights are contemplated