Historical growth rates and changing climatic sensitivity of boreal conifers

This thesis is concerned with the expression of relatively long-timescale growth forcing in tree-ring chronologies. The operation of different standardisation techniques, used in dendroclimatology to remove internal, non-climate related growth trends in measured series of ring-widths, is explored with an emphasis on the efficiency of the Regional Curve Standardisation (RCS) technique. The approach adopted here makes extensive use of concepts taken from tree-growth models and is based on the assumption that common external growth forcing operates through its influence on photosynthesis. A definition, of the growth rate of trees in terms of the carbon production by unit foliage, is the rationale that underlies this work and leads to the use of a multiplicative model for processing individual tree and chronology indices. The presence of a “common signal” in series of tree measures can lead to the distortion of the shape of detrending curves and a problem with bias in chronologies. Problems of the RCS technique are identified which are associated with tree age and diameter-related bias, arising from the use of ring-width to establish tree growth rates, regardless of tree diameter. These problems are manifest as “end effects” in chronology development and are most significant in the most recent century. Alternative, significant modifications of the RCS approach are proposed: the Multiple RCS (MRCS) and the Size-Adjusted RCS (SARCS) methods which greatly mitigate these problems. These are made possible by the introduction of two new concepts in dendroclimatology: the “best fit means” method and the use of “signal-free measures”. The concept of the mechanical strength of trees is used to simulate tree growth from series of ring-width measures and a “process based standardisation” (PBS) model is developed. The PBS model is tested and shown to be a feasible alternative to existing standardisation techniques

Genetic evaluation of US dairy cattle in the presence of preferential treatment

Data were simulated according to the USDA animal model for the purpose of determining bias in female and sire predicted transmitting abilities (PTA) caused by preferential treatment (PT). Bias in female PTA ranged from six to 39 percent of the PT effect and varied according to number of records on the PT cow, whether all or only second and later records received PT, and which, if any, relatives received PT. Bias in sire PTA ranged from 10 to 77 percent of the PT effect and depended largely on proportion of daughters receiving PT and, to a lesser extent, total number of daughters. Distribution of daughters across herds also affected bias in sire PTA. As more PT daughters were placed in a single herd, bias decreased because a larger portion of the PT effect was accounted for by the management group and sire by herd interaction effects;Biases found were large. Thus, preliminary research was conducted on possible methods to correct for PT. Three approaches were examined: power transformations applied to the phenotypic records, fitting a random PT effect in the model for genetic evaluation, and a two-group mixture model. Transforming records with a power of.1 reduced bias to zero but had a very adverse effect on ranking. The power transformation cannot be recommended for use in practice;The random PT and mixture model approaches, however, both hold promise as a means to correcting for PT in genetic evaluation. When PT records were identified, the random PT effect reduced bias to nearly zero. Further development of the random PT approach should focus on improving the identification step. PT records were identified, at best, 50 to 60 percent of the time;The mixture model brought about only a small reduction in bias, but this reduction was achieved without any loss in mean true transmitting ability of the top 5% of cows. The shortcoming was the conditional probabilities of PT for PT records. Even in the best case, average probability was only.27. Utilizing the correct variance of residuals may be adequate to improve calculation of these conditional probabilities

Perceptions of the Value of Financial Education in African American Creditworthiness

Research suggests a disparity for African Americans within the banking system, as they are denied credit at a higher rate than other ethnic groups. The purpose of this phenomenological study was to explore the perceptions of African Americans financial training in regards to qualifying for consumer loans. The conceptual framework was based on seminal theories on credit risk assessment and critical race theory. The research questions were designed to address banking officials\u27 perceptions of financial training and the effectiveness of training in improving African Americans\u27 credit. A phenomenological design was employed with the purposeful sample of 9 banking officials within the African American community from 4 states within the Southeast United States. Data analysis consisted of interpretive phenomenological analysis of lending documentation and interviews. The thematic analysis of face-to-face interviews were collected, coded, validated, and triangulated. An emergent theme concluded that banking officials acknowledged the important role financial competency plays in consumers\u27 ability to access financial resources. The findings indicated that exposure to comprehensive financial training may increase African Americans creditworthiness. The results of the study could impact perceptions of the value of financial education and its usefulness in enhancing African American creditworthiness. The study may create positive social change by improving African Americans ability to obtain consumer loans and promote African Americans\u27 financial welfare

The Production of Biobutanol from Biomass Via a Hybrid Biological/Chemical Process

Biobutanol use as a fuel began in the late 19th century. Problems remain in economic viability. A review of the state of the art and need for technical advances is presented. The technical potential of producing biofuel from a naturally occurring macroalgae was studied. The algae grow in Jamaica Bay, New York City, in contaminated water. The process consisted of mechanical harvesting, drying, grinding, and acid hydrolysis to form an algal sugar solution. Clostridium beijerinckii and C. saccharoperbutylacetonicum were used in an acetone butanol ethanol (ABE) fermentation to make butanol. Fermentation was followed by distillation Butanol concentrations during fermentation reached 4 g/L. The recovery of reducing sugars in the media was 0.29 g butanol/g sugar. Feedstock with greater than 7 g/L butyric acid caused death of the butanol-producing bacteria. The kinetics of the production of 1-octadecanol from octadecanoic acid was investigated in a liquid-phase trickle-bed reactor by hydrogenation. The primary reactions occurring in the reactor were the desired conversion of octadecanoic acid to 1-octadecanol and the subsequent undesired conversion of 1-octadecanol to octadecane. A series-parallel kinetics model first order in acid and zero order in hydrogen was developed to predict these two reactions. The activation energies of the reactions were 63.7.8 and 45.6 kJ/mole, respectively. The conversion of octadecanoic acid and the selectivity to the desired product as functions of temperature, space velocity, and inlet octadecanoic acid concentration were then estimated. The model predicts maximum productivity of 1-octadecanol at higher temperatures and short residence times. Parametric plots show productivity to be ≥0.48 g 1-octadecanol/g octadecanoic acid at 566 oF and a 0.1 h residence time. The model from the 1-octadecanoic acid study was fitted to several sets of data for the hydrogenation of butyric acid to butanol in the temperature regime of 300-400 oF and pressures of 700-1000 psig. The model failed to accurately predict the final concentrations of 1-butanol and butane. Reasons for this are suggested and future work to fix this problem is presented and discussed

The Ca2+-dependent Binding of Calmodulin to an N-terminal Motif of the Heterotrimeric G Protein beta Subunit

Ca2+ ion concentration changes are critical events in signal transduction. The Ca2+-dependent interactions of calmodulin (CaM) with its target proteins play an essential role in a variety of cellular functions. In this study, we investigated the interactions of G protein beta gamma subunits with CaM. We found that CaM binds to known beta gamma subunits and these interactions are Ca2+-dependent. The CaM-binding domain in Gbeta gamma subunits is identified as Gbeta residues 40-63. Peptides derived from the Gbeta protein not only produce a Ca2+-dependent gel mobility shifting of CaM but also inhibit the CaM-mediated activation of CaM kinase II. Specific amino acid residues critical for the binding of Gbeta gamma to CaM were also identified. We then investigated the potential function of these interactions and showed that binding of CaM to Gbeta gamma inhibits the pertussis toxin-catalyzed ADP-ribosylation of Galpha o subunits, presumably by inhibiting heterotrimer formation. Furthermore, we demonstrated that interaction with CaM has little effect on the activation of phospholipase C-beta 2 by Gbeta gamma subunits, supporting the notion that different domains of Gbeta gamma are responsible for the interactions of different effectors. These findings shed light on the molecular basis for the interactions of Gbeta gamma with Ca2+-CaM and point to the potential physiological significance of these interactions in cellular functions

Gα16, a G Protein α Subunit Specifically Expressed in Hematopoietic Cells

Signal-transduction pathways mediated by guanine nucleotide-binding regulatory proteins (G proteins) determine many of the responses of hematopoietic cells. A recently identified gene encoding a G protein α subunit, Gα16, is specifically expressed in human cells of the hematopoietic lineage. The Gα16 cDNA encodes a protein with predicted Mr of 43,500, which resembles the Gq class of α subunits and does not include a pertussis toxin ADP-ribosylation site. In comparison with other G protein α subunits, the Gα16 predicted protein has distinctive amino acid sequences in the amino terminus, the region A guanine nucleotide-binding domain, and in the carboxyl-terminal third of the protein. Cell lines of myelomonocytic and T-cell phenotype express the Gα16 gene, but no expression is detectable in two B-cell lines or in nonhematopoietic cell lines. Gα16 gene expression is down-regulated in HL-60 cells induced to differentiate to neutrophils with dimethyl sulfoxide. Antisera generated from synthetic peptides that correspond to two regions of Gα16 specifically react with a protein of 42- to 43-kDa in bacterial strains that overexpress Gα16 and in HL-60 membranes. This protein is decreased in membranes from dimethyl sulfoxide-differentiated HL-60 cells and is not detectable in COS cell membranes. The restricted expression of this gene suggests that Gα16 regulates cell-type-specific signal-transduction pathways, which are not inhibited by pertussis toxin

Distinct forms of the ß subunit of GTP-binding regulatory proteins identified by molecular cloning

Two distinct β subunits of guanine nucleotide-binding regulatory proteins have been identified by cDNA cloning and are referred to as β 1 and β 2 subunits. The bovine transducin β subunit (β 1) has been cloned previously. We have now isolated and analyzed cDNA clones that encode the β 2 subunit from bovine adrenal, bovine brain, and a human myeloid leukemia cell line, HL-60. The 340-residue Mr 37,329 β 2 protein is 90% identical with β 1 in predicted amino acid sequence, and it is also organized as a series of repetitive homologous segments. The major mRNA that encodes the bovine β 2 subunit is 1.7 kilobases in length. It is expreβed at lower levels than β 1 subunit mRNA in all tiβues examined. The β 1 and β 2 meβages are expreβed in cloned human cell lines. Hybridization of cDNA probes to bovine DNA showed that β 1 and β 2 are encoded by separate genes. The amino acid sequences for the bovine and human β 2 subunit are identical, as are the amino acid sequences for the bovine and human β 1 subunit. This evolutionary conservation suggests that the two β subunits have different roles in the signal transduction process

Inhibitory control as a mediator of bidirectional effects between early oppositional behavior and maternal depression.

Maternal depression is an established risk factor for child conduct problems, but relatively few studies have tested whether children's behavioral problems exacerbate mothers' depression or whether other child behavioral characteristics (e.g., self-regulation) may mediate bidirectional effects between maternal depression and child disruptive behavior. This longitudinal study examined the parallel growth of maternal depressive symptoms and child oppositional behavior from ages 2 to 5; the magnitude and timing of their bidirectional effects; and whether child inhibitory control, a temperament-based self-regulatory mechanism, mediated effects between maternal depression and child oppositionality. A randomized control trial of 731 at-risk families assessed children annually from ages 2 to 5. Transactional models demonstrated positive and bidirectional associations between mothers' depressive symptoms and children's oppositional behavior from ages 2 to 3, with a less consistent pattern of reciprocal relations up to age 5. Mediation of indirect mother-child effects and child evocative effects depended on the rater of children's inhibitory control. Findings are discussed in regard to how child evocative effects and self-regulatory mechanisms may clarify the transmission of psychopathology within families