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Hester, Mildner, and Spencer: Great Basin Atlatl Studies
No full textGreat Basin Atlatl Studies.T. R. Hester, M. P. Mildner, and L. Spencer. Ramona, California: Ballena Press Publications in Archaeology, Ethnology, and History No. 2, 1974. 60 pp., 5 tables, 2 pls., 19 figs. $4.95 (paper)
Response of mature Norway spruce (Picea abies) to elevated atmospheric CO²
No full textThe aim of this thesis was to identify pathways and rates of C allocation in tall forest trees, and to identify effects of elevated CO2 on respiratory processes and root growth. Correspondingly, this thesis is divided into three separate parts:
Chapter 2)
Long-term 13C labeling provides evidence for temporal and spatial carbon allocation patterns in mature Picea abies (published in Oecologia)
Chapter 3)
Respiratory fluxes and fine root responses in mature Picea abies trees exposed to elevated atmospheric CO2 concentrations (published in Biogeochemistry)
Chapter 4)
Photosynthetic enhancement and diurnal stem and soil carbon fluxes in a mature Norway spruce stand under elevated CO2 (published in Environmental and Experimental Botany)
The work was conducted at the Swiss canopy crane (SCC) research site in Hofstetten near Basel, Switzerland, and explored signals produced by free air CO2 enrichment (FACE) in 110-year-old, ca. 37m tall P. abies trees. Chapter 2 capitalizes on the isotopic signal carried by the CO2 gas used for CO2 enrichment, yet does not address effects of elevated CO2 as such, but rather deals with basic questions of C transfer in tall trees. Chapter 3 explores the longer-term CO2 effects on mature P. abies (i.e. 2.5 years), whereas chapter 4 reports short-term (diurnal) responses to elevated CO2. In the following, I will provide a summary of the results of the three chapters of my thesis, extended by a conclusion that links these chapters.
Chapter 2) Long-term 13C labeling of Picea abies
As a side effect, the FACE technique provided the unique opportunity to study C translocation within the tree body using the stable isotope 13C signal the FACE gas carries. Since control trees are not (can not) be similarly labeled with 13C the tree responses to elevated CO2 were not the subject of this chapter. Yet, FACE resembles a continuous 13C labeling of new assimilates. Tracking the fate of these assimilates over a period of 2.5 years in tall trees offers new insights in tree C relations under steady state conditions. We tracked 13C signals in mature P. abies trees at a high spatial and temporal resolution, i.e. from the canopy (needles and branchlets), down to the tree trunk (year rings and stem CO2 efflux), and into the soil compartment (fine roots, fungi, soil CO2 efflux). The following key questions were answered:
1. How long does it take for new C to arrive at a certain tissue type or respiratory flux?
2. What is the proportional contribution of newly assimilated C to concurrent tree tissue production and maintenance?
3. How long does it take until old C is replaced by new C in various tissues?
Generally, we observed a reduction of new assimilate investment with distance from the canopy, which can be explained by a progressive dilution of new C into the existing C storage pools in the tree. New sunlit needles (and adjacent branchlets) exhibited a nearly 100% share of new C, whereas shaded needles also used some older C. Stem wood isotope signals evidenced a complete exchange of old C by new C within 2 years. Fine roots contained only 49-56% new C, hence are using older C pools for a longer period of time. A surprisingly low fraction of novel C (26-43%) was recovered from fungal sporocarps, presumably related to the influence of neighboring trees that were not CO2 enriched. The first appearance of new C in soil and stem CO2 release occurred after 12 days, reflecting a lag due to the long transport distances in these 37m tall trees. The CO2 released by stems was composed of 50% new C already in the first year of FACE. In contrast, only ca. 15% new C contributed to soil CO2 efflux, reflecting the use of older substrates, and the influence of older roots and litter from neighboring trees blown in by wind.
These findings indicate a rapid contribution of new assimilates to tissue formation, and thus, a fast replacement of mobile C reserves with new C, and a progressive signal dilution from treetop to the bottom. The two-year replacement time in stem xylem shows that the storage pool is contributing substantially to tree ring formation. We speculate that the turnover of mobile C pools might be enhanced by elevated CO2, and the metabolic costs of this turnover might compensate for some of the extra C taken up at elevated CO2 concentrations, and thus, may explain the ‘missing C’ at the whole tree level. These metabolic costs are unlikely to produce measurable signals at tissue level, given the large heterotrophic volume of such trees.
Chapter 3) Responses of Picea abies to elevated CO2
Most FACE experiments revealed strong initial growth responses to elevated CO2 that diminished over the first 3 years (Körner 2006). Since growth in natural undisturbed systems is commonly not showing a continued stimulation under altered CO2 for reasons of nutrient supply, a step increase in CO2 concentration should induce overflow responses in terms of enhanced respiration and fine root expansion, the latter in order to forage for nutrients to balance the additional C input. In this web-FACE experiment, established in a natural Central European forest, we investigated mature ca. 110-year-old P. abies trees in their steady state of growth (C cycle coupled to the nutrient cycle; Körner 2006). In this publication we were particularly interested in:
1. Seasonal shifts in assimilate allocation;
2. Locations of C-investment;
3. Residence times (turnover) of mobile C pools.
We tracked the respiratory and fine root growth responses of these trees before and directly after the start of FACE, and for further 2.5 years. The CO2 concentration in the canopy (e.g. 540 ppm) was about twice the pre-industrial level. We anticipated a stimulation of CO2 release, and faster root expansion into root-free soil space (in-growth core method), but we also expected a weaker signal in these mature trees compared to young trees. Seasonal stem CO2 efflux did not show any sign of increase during the 2.5 years under elevated CO2. This result lines up with the lack of any stem radial growth response (ongoing work). Fine roots (<0.5-2 mm) did not accumulate more dry matter in the course of 2.5 years of CO2 fertilization. Interestingly, we observed a slight but significant reduction of CO2 release from the soil despite clear evidence by isotopic signals that novel assimilates arrived in the soil.
These data suggest that such mature trees do not even show a transient stimulation of respiration to a step increase of CO2, as was observed in other FACE experiments using much younger trees (Norby et al. 2010). Other growth-limiting factors appear to prevent more vigorous tree growth and thus, metabolism at high CO2 (Norby & Zak 2011). N limitation can be excluded at our site because of high N-deposition. A part of the extra C taken up by needles at elevated CO2 might have been allocated belowground, however, not to fine roots. Conversely, slightly reduced rather than increased rates of soil CO2 efflux implies that respiration of roots and/or soil organisms declined under elevated CO2, implying an overall reduced C allocation into the rhizosphere. We assume that extra C absorbed by foliage is either retained within the tree body (stored carbohydrates), recycled by respiration rates below detection limit across all heterotrophic plant tissues, or lost through enhanced leaching of dissolved organic or inorganic carbon (DIC/DOC).
In summary, we conclude that mature P. abies trees at our site are roughly C saturated at current CO2 concentrations. We find no indication of stimulated belowground metabolic activity (fine roots and soil CO2 efflux).
Chapter 5) Diurnal courses in P. abies under elevated CO2
Leaf-level photosynthetic stimulation in trees following a step increase of atmospheric CO2 was commonly observed in CO2 enrichment experiments, however, mostly without corresponding growth stimulation. Hence, the fate of this additional C input in tree still is not fully resolved, but C overflow mechanisms such as respiratory C losses might account for this C surplus. Since these potential variations in C fluxes might not be detectable on a daily basis, a response may emerge on shorter timescales (i.e. on a diurnal basis). This chapter (co-authorship) explored the diurnal variations in C fluxes (i.e. net photosynthesis, and CO2 efflux from the forest floor and the from stem) in mature P. abies trees exposed to elevated CO2 in the SCC web-FACE experiment. We tracked the diurnal variations of these fluxes on a summer day shortly before the onset of FACE, and twice during the FACE periods in summer 2009 and 2010.
Results from this study confirmed a CO2-induced photosynthetic stimulation shortly after the onset of FACE, and a change in magnitude throughout the day. Intriguingly, this stimulation of Anet diminished in the second year under FACE, indicating photosynthetic downregulation in these trees. The respiratory fluxes from P. abies stems, as observed on a seasonal basis (chapter 4), were not affected by high levels of CO2 whereas soil CO2 efflux decreased slightly with prolonged exposure to elevated CO2. Further, the diurnal patterns of CO2 release (stems and soil) were not altered by CO2 enrichment.
In conclusion, despite larger C input into the tree system in the first year of FACE, respiratory overflow mechanisms could not be observed even on a diurnal basis, corroborating our results obtained in chapter 4. Additionally, the photosynthetic downregulation observed at high CO2 confirms the assumption that these trees are C saturated.
Final conclusions
Stimulatory effects of elevated CO2 on tree growth are constrained by several growth-limiting factors, mainly availability of nutrients and other resources, and the developmental stage (age) of a tree. This thesis for the first time illuminates the current (chapter 2) and future (chapters 3 and 4) C balance of mature evergreen conifers subjected to prospective CO2 levels of 540 ppm in a near-natural forest in Switzerland. Isotopic labeling of fresh assimilates successfully depicted the pathways of C in these trees, thus provided basic insights into how P. abies trees handle the distribution of assimilates. We observed remarkable tree-specific variations in all pre-treatment measurements, emphasizing the importance of recording baseline conditions prior to any experiment. At current CO2 levels, all investigated tissues (except for needles in the sun), and respiratory fluxes depended only partly on new assimilates. The further away from the upper tree canopy, the greater the role of old C stores for new tissue formation and respiration. Since no aboveground growth stimulation was observed (ongoing works) despite higher but transient rates of photosynthesis, and since stem CO2 efflux remained unaffected by elevated CO2, we assume that the extra C assimilated in the first year is dissipated via respiration associated with C turnover (phloem) at rates below detection limit. These processes seem to be too small to be detectable but their accumulated rate along the entire phloem system might account for the unresolved ‘missing C’ at elevated CO2. We found no evidence for increased C investment belowground at elevated CO2 that might also account for some of the higher leaf-level C input at elevated CO2.
References
Körner C (2006) Plant CO2 responses: An issue of definition, time and resource supply. New Phytologist 172:393-411
Norby RJ, Warren JM, Iversen CM, Medlyn BE, McMurtie RE (2010) CO2 enhancement of forest productivity constrained by limited nitrogen availability. Proceedings of the National Academy of Sciences of the United States of America 107:19368-19373.
Norby RJ, Zak DR (2011) Ecological lessons from free-air CO2 enrichment (FACE) experiments. Annual Review of Ecology, Evolution, and Systematics 42:181-20
Dr. Duane M. Jackson, Morehouse College, July 2011
No full textThis video is a conversation with Dr. Duane M. Jackson. Dr. Jackson talks about his paper, "Recall and the Serial Position Effect: The Role of Primacy and Recency on Accounting Students' Performance." Jackie Daniel, AUC Woodruff Library, is the interviewer
"Reflections on the subject of Emigration from Europe with a view to Settlement in the United States" By M. Carey.
No full text"Reflections on the subject of Emigration from Europe with a view to Settlement in the United States: containing bried sketches of the moral and political character of those states.
By M. Carey, member of the American philosophical, and of the American Antiquarian Society, and author of The Olive Branch, Cindiciae Hibernicae, essays on banking, on political economy, and on internal improvement.
To which are now added the English editor's comments on the subject; together with Important Advice to Emigrants, and Cautions Against Impositions Practiced in the Outports
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Dr. Glendon Swarthout
No full textHosted by Roger M. Busfield, MSU Assistant Professor of Speech and Theater, Meet the Author is designed to introduce a general audience to a contemporary author and their work through in-depth interviews. This episode features a conversation between Dr. Glendon Swarthout, prolific author and English professor at MSU, and assistant professors Sam S. Baskett and Theodore B. Strandness
Simulation of thermal plant optimization and hydraulic aspects of thermal distribution loops for large campuses
No full textFollowing an introduction, the author describes Texas A&M University and its utilities system. After that, the author presents how to construct simulation models for chilled water and heating hot water distribution systems. The simulation model was used in a $2.3 million Ross Street chilled water pipe replacement project at Texas A&M University. A second project conducted at the University of Texas at San Antonio was used as an example to demonstrate how to identify and design an optimal distribution system by using a simulation model. The author found that the minor losses of these closed loop thermal distribution systems are significantly higher than potable water distribution systems. In the second part of the report, the author presents the latest development of software called the Plant Optimization Program, which can simulate cogeneration plant operation, estimate its operation cost and provide optimized operation suggestions. The author also developed detailed simulation models for a gas turbine and heat recovery steam generator and identified significant potential savings. Finally, the author also used a steam turbine as an example to present a multi-regression method on constructing simulation models by using basic statistics and optimization algorithms. This report presents a survey of the author??s working experience at the Energy Systems Laboratory (ESL) at Texas A&M University during the period of January 2002 through March 2004. The purpose of the above work was to allow the author to become familiar with the practice of engineering. The result is that the author knows how to complete a project from start to finish and understands how both technical and nontechnical aspects of a project need to be considered in order to ensure a quality deliverable and bring a project to successful completion. This report concludes that the objectives of the internship were successfully accomplished and that the requirements for the degree of Degree of Engineering have been satisfied
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Karl an Herrn M. Philoteknos, in Antwort auf dessen Brief im 7ten Bande des Briefwechsels. S. 1. (1)
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Fritze an Karln in Antwort auf dessen Brief im 6ten Theile; Seite 1 bis 49. (38)
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Lottchen an Herrn M. Philoteknos. (164)
[Ein Nachschreiben von Herrn Bendas Composition des Findelkindes]. (239)
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Erster Auftritt. Das Theater stellt eine Studierstube in des Rectors Wohnung vor. (243)
Zweyter Auftritt. Fabrizius. Mildner. (244)
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Vierter Auftritt. Mildner. Julchen. Karl. (259)
Fünfter Auftritt. Mildner. Julchen. Karl. Angler. (270)
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Dritter Auftritt. Stürmer. Angler. Mildner. (307)
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Fünfter Auftritt. Mildner. Angler (der zurück kömmt.) (312)
Sechster Auftritt. Die Vorigen. Stürmer. (317)
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Achter Auftritt. Die unterste Stube des Rectors, wo noch der Tisch gedeckt steht, aber das Essen abgetragen ist. Fabrizius. Frau Mildnerin. Karl. (324)
Neunter Auftritt. Fabrizius. Frau Mildnerinn. Julchen. Mildner. Karl (mit des Herrn Rectors hut und Stock.) (328)
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Eilfter Auftritt. Fabrizius. Mildner. Frau Mildnerin. Angler. Julchen. Karl. Regimentsquartiermeister. (343)
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Intern experience at CH���M Hill, Inc.: an internship report
No full textIncludes author's vita"Submitted to the College of Engineering of Texas A&M University in partial
fulfillment of the requirement for the degree of Doctor of Engineering."Includes bibliographical referencesA review of the author's internship experience with CH���M HILL, Inc.
during the period September 1975 through May 1976 is presented. During this nine month
internship the author worked as an Engineer II in the Industrial Processes discipline of this
large consulting engineering firm... The author's prime responsibility was as one of three
lead design engineers on the design of a large wastewater treatment facility for a pulp mill
in Hoquiam, Washington owned by ITT Rayonier Inc. The work generally consisted of the design
of individual treatment units and associated piping and pumping. The purpose of the project
was to provide wastewater treatment capabilities that would satisfy the effluent limitations
(standards) imposed upon the mill by the State of Washington Department of Ecology and the
U.S. Environmental Protection Agency. The author's assignment also entailed necessary
interaction with the project manager and other CH���M HILL design engineers and support staff
members, the client's representatives, and representatives of two other consulting engineering
firms working on the project. Thus, the internship position at CH���M HILL provided considerable
experience coordinating the author's work with the work of other engineers, guiding the design
and administrative efforts of a support staff, and interacting regularly with the client and
other consulting firms. This broad exposure to a variety of engineering and organizational
problems provided a valuable educational experience
Transition to turbulence in a qblique shock-wave/boundary-layer interaction at M=15
No full textDirect numerical simulations are carried out for different forcing techniques to trigger transition during the interaction between an oblique shock-wave and a laminar boundary-layer at M = 1.5. Three forcing methods are used: a) forcing of oblique unstable modes, whose shape and behaviour are determined by the local linear stability theory, b) broadband free-stream acoustic disturbances, and c) a cold plasma flow control device. While the oblique-mode breakdown is dominant for low-amplitude forcing, long streaky structures drive the transition process in a high-amplitude disturbance environment. LES are also performed on the experimental setup by the Institute of Theoretical and Applied Mechanics (ITAM) from Novosibirsk State University with cold plasma actuation. As well as the disturbance type, the effect of Reynolds number and forcing amplitude will be investigated
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