Showing papers by "University of New Brunswick published in 1994"

Dehydration melting of a basaltic composition amphibolite at 1.5 and 2.0 GPa: implications for the origin of adakites

Abstract: This study presents the results of dehydration melting experiments on a basaltic composition amphibolite under conditions appropriate to a hot slab geotherm (1.5 and 2.0 GPa and temperatures of 850 to 1150° C). Dehydration melting produces an omphacitic augite and garnet bearing residue coexisting with rhyolitic to andesitic composition melts. At 1.5 GPa, the amphibolite melts in two stages between 800 and 1025° C. The 2.0 GPa data also define two melting stages. At 2.0 GPa, the first stage involves nearly modal melting of the original amphibolite minerals (qtz, pl, amp) to produce melt + cpx + grt. During the second stage, the eclogite restite melts non-modally (0.86 cpx + 0.14 grt = 1 melt). The experimental results were combined with data from the literature to generate a composite P-T phase diagram for basaltic composition amphibolites over the 800 to 1100° C temperature range for pressures up to 2.0 GPa. Comparison of the major element compositions of the experimentally produced melts with compositions of presumed slab melts (adakites) shows that partial melting of amphibolite at conditions appropriate to a hot-slab geotherm produces melts similar to andesitic and dacitic adakites except for significant MgO and CaO depletions. Trace element modelling of amphibolite dehydration melting using the 2.0 GPa melting reactions produces REE abundances similar to those of adakites at 10–15 wt% batch melting, but the models do not reproduce the high Sr/Y ratios characteristic of adakites. Taken together, the major and trace element results are not consistent with the derivation of adakites by dehydration melting of the subducted slab with little or no interaction with the mantle wedge or crust. If adakites are partial melts of the subducted slab, they must undergo significant interaction with the mantle and/or crust, during which they acquire a number of their distinctive characteristics.

Determination of the optimal aligned spacing between the Shine-Dalgarno sequence and the translation initiation codon of Escherichia coli mRNAs.

Abstract: The prokaryotic mRNA ribosome binding site (RBS) usually contains part or all of a polypurine domain UAAGGAGGU known as the Shine-Dalgarno (SD) sequence found just 5' to the translation initiation codon. It is now clear that the SD sequence is important for identification of the translation initiation site on the mRNA by the ribosome, and that as a result, the spacing between the SD and the initiation codon strongly affects translational efficiency (1). It is not as clear, however, whether there is a unique optimal spacing. Complications involving the definition of the spacing as well as secondary structures have obscured matters. We thus undertook a systematic study by inserting two series of synthetic RBSs of varying spacing and SD sequence into a plasmid vector containing the chloramphenicol acetyltransferase gene. Care was taken not to introduce any secondary structure. Measurements of protein expression demonstrated an optimal aligned spacing of 5 nt for both series. Since aligned spacing corresponds naturally to the spacing between the 3'-end of the 16S rRNA and the P-site, we conclude that there is a unique optimal aligned SD-AUG spacing in the absence of other complicating issues.

Common and specific dimensions of self-reported anxiety and depression: implications for the cognitive and tripartite models.

Abstract: The common and specific symptom dimensions of anxiety and depression proposed by the tripartite (L.A. Clark & D. Watson, 1991 c) and cognitive (A.T. Beck, 1976, 1987) models were investigated in 844 psychiatric outpatients and 420 undergraduates. Principal-factor analyses with oblique rotations performed on the 42 items of the Beck Depression Inventory and Beck Anxiety Inventory for both samples revealed that there were 2 correlated factors. Depression and Anxiety. Second-order factor analyses of the interfactor correlation matrices indicated a large general distress or negative affect factor underlying the relationship between the 2 first-order factors. Specific depression and anxiety dimensions were apparent even after we controlled for negative affect. The results were consistent with both the tripartite and cognitive models, with the cognitive and motivational symptoms specific to depression and the physiological arousal symptoms unique to anxiety.

Reaching for objects in VR displays: lag and frame rate

Abstract: This article reports the results from three experimental studies of reaching behavior in a head-coupled stereo display system with a hand-tracking subsystem for object selection. It is found that lag in the head-tracking system is relatively unimportant in predicting performance, whereas lag in the hand-tracking system is critical. The effect of hand lag can be modeled by means of a variation on Fitts' Law with the measured system lag introduced as a multiplicative variable to the Fitts' Law index of difficulty. This means that relatively small lags can cause considerable degradation in performance if the targets are small. Another finding is that errors are higher for movement in and out of the screen, as compared to movements in the plane of the screen, and there is a small (10%) time penalty for movement in the Z direction in all three experiments. Low frame rates cause a degradation in performance; however, this can be attributed to the lag which is caused by low frame rates, particularly if double buffering is used combined with early sampling of the hand-tracking device.

Climatic changes in areas adjacent to the North Atlantic during the last glacial-interglacial transition (14-9 ka BP): a contribution to IGCP-253

Abstract: This paper presents a summary of the evidence for climatic changes during the last glacial-interglacial transition (14-9 ka BP) in land areas adjacent to the North Atlantic. It is a synthesis of the results of the 12 regional summaries compiled by contributors to the North Atlantic Seaboard Programme of IGCP-253 that are published separately in this issue of journal of Quaternary Science. Eighteen palaeotemperature curves are compared and arranged in three transects, one from southern Europe to Spitsbergen, a second from Ireland to Poland, and the third from southern New England to the Labrador-Baffin Shelf area. Ten maps are presented that summarise the synoptic climatic conditions of the region in 500-year time periods. The purpose of the exercise is to examine the extent to which any emerging patterns support the Ruddiman and Mclntyre model of large-scale shifts in the position of the oceanic Polar Front during the last glacial-interglacial transition. Some broad agreement emerges, although the influence of oceanic changes is diminished in areas that lay in close proximity to the Laurentide and Fennoscandian ice sheets. Attention is drawn to limitations in the compilations and to the potential for improved models in the future.

Behavior at mealtimes and the young child with cystic fibrosis

Abstract: Recent work has indicated that behavioral feeding disorders may contribute to failure to thrive in patients with cystic fibrosis (CF). This study compared the incidence of behavioral problems at mealtime, parenting stress, and nutritional intake for a sample of 22 children with CF and a matc

Violent pornography, antiwoman thoughts, and antiwoman acts: In search of reliable effects

Abstract: In this article, we critique the literature concerning the prevalence and effects of violent pornography and describe two experiments in which we sought to produce effects of violent pornography on men's fantasies, attitudes, and behaviors toward women. Our critique of the literature revealed that findings for the prevalence and effects of violent pornography are highly inconsistent, and we identified methodological and conceptual limitations that may contribute to the unreliability of findings in this area. Our two experiments involved creation of conditions that should have been sufficient to produce effects of violent pornography on men's fantasies, attitudes, and behaviors toward women, but which produced essentially no such effects. Discussion focuses on factors that may help explain the unreliability of effects of violent pornography on men's fantasies, attitudes, and behaviors toward women, within the research procedures that are commonly used in this area, and on the need to improve methodological...

Joint determination of production quantity, inspection schedule, and control chart design

Abstract: This paper presents a model for jointly determining an economic production quantity, inspection schedule and control chart design of an imperfect production process. The process is subject to the occurrence of a non-Markovian shock having an increasing failure rate. The product quality of the process is monitored under the surveillance of an x¯-control chart The objective is to determine the optimal control chart design parameters and production quantity so as to minimize the expected total cost (the quality control cost and the inventory control cost) per unit time. Both uniform and non-uniform inspection schemes are considered. For non-uniform inspection schemes, the length of the inspection intervals are regulated to maintain a constant integrated hazard rate over each inspection interval. Examples of Weibull shock models having increasing failure rates are provided. It is shown that the non-uniform and decreasing process inspection intervals scheme resulted in a lower cost man the uniform ins...

Cortisol, glucose and hematocrit changes during acute stress, cohort sampling, and the diel cycle in diploid and triploid brook trout ( Salvelinus fontinalis Mitchill)

Abstract: In this study, groups of diploid (control) and triploid brook trout were subjected to a 5 min acute handling/confinement stress. Blood samples were collected from equal numbers of diploid and triploid fish at regular predetermined intervals, beginning prior to confinement and continuing for up to 3h after confinement. These blood samples were used for the measurement of hematocrit and plasma cortisol and glucose concentrations. The effects of cohort sampling and the diel cycle on these variables were also analysed. Except for minor differences, both groups responded similarly to the acute stress, with short-term elevations in plasma cortisol and hematocrit levels, and a more sustained increase in plasma glucose levels. No significant differences were found between diploid and triploid fish in their reactions to cohort sampling. However, the act of removing an individual from a tank caused significant changes in plasma cortisol levels in cohorts remaining in that tank (p < 0.001). Significant diel effects were observed for both ploidy groups in plasma cortisol (p < 0.05) but not in plasma glucose or hematocrit.

Becoming strangers: the changing family caregiving relationship in Alzheimer's disease

Abstract: Alzheimer-type dementia (AD) is an insidious pervasive debilitating disorder that destroys the affected person's capacity for self-care. In this grounded theory study, we explored the reciprocal process of becoming strangers in which eastern Canadian family caregivers and care recipients with AD interact on a continuum from intimacy to alienation through dimensions of dawning, holding on and letting go. The findings illuminate the experiences of family members who struggle on a daily basis with their commitment to the person they knew and their increasing detachment from the stranger that person has become. With the increasing emphasis on home care, these findings offer insights for individual care and health policy development.

Alkaline degradation of ALCELL® lignin

Abstract: ALCELL® lignin has been depolymerized by alkaline hydrolysis using a magnetically stirred batch autoclave. The effects of reaction temperature and time, combined into a single parameter (the reaction ordinate), were quantified in terms of the yields of unreacted lignin and identifiable liquid degradation products. At a high treatment severity, about 40% of the unreacted lignin is recovered as an alkaline-insoluble reactor residue, whilst at low to medium severities, this lignin is essentially all recovered by acid precipitation from the product mixture. The predominant identifiable liquid phenolic products ranged from guaiacol and syringol at low severities to catechol and its derivatives at high severities. Increasing concentrations of sodium hydroxide from 0 to 4% increased the conversion of lignin to liquid products from 7 to 30%. Based on the initial lignin, a maximum concentration of 4.4% identifiable phenols (mostly syringol = 2.4%), was found when using 0.5% NaOH, with a subsequent decrease with increasing alkali concentration. When a 50% ethanol-water mixture was used as the solvent, conversion remained essentially the same, but the methylene chloride solubles increased from 5 to 19%.

Perceived Control and Appraisal of Obsessional Intrusive Thoughts: A Replication and Extension

Abstract: The present study had two purposes: 1) to examine the relationship between tendency to experience obsessional intrusive thoughts and tendency to worry; 2) to replicate and extend earlier findings (Purdon and Clark, 1993, 1994) on appraisal and thought suppression strategies in the persistence and control of obsessional intrusive thoughts A sample of 160 college students were administered the Revised Obsessional Intrusions Inventory (ROII), the Penn State Worry Questionnaire (PSWQ), the Beck Depression Inventory (BDI), and the White Bear Suppression Inventory (WBSI) The ROII total score had minimal association with worry, trait thought suppression, or depressive symptoms, thereby supporting the distinctiveness of obsessional intrusive thoughts Hierarchical multiple regression analyses revealed that cognitive appraisal, especially worries that the intrusion might come true in real life, accounted for a significant amount of variance in thought frequency and controllability Thought suppression strategies accounted for substantially less variance in both frequency and control of intrusive thoughts The results are discussed in terms of their support for Rachman's (1993) and Salkovskis' (1985, 1989) theories regarding the role of personal responsibility in the persistence of obsession-like intrusive thoughts

Ground-state energies for the helium isoelectronic series

Abstract: Variational calculations are reported for the ground state of the helium isoelectronic series. An ansatz is introduced and it achieves an accuracy comparable to that hitherto achieved only with basis functions containing logarithmic terms. Energies accurate to better than one part in ${10}^{14}$ are obtained for the ground states of He through ${\mathrm{Ne}}^{8+}$ using 308-term expansions, and the ground state of ${\mathrm{H}}^{\mathrm{\ensuremath{-}}}$ using 455 terms.

Spherically symmetric anisotropic fluid ICKV spacetimes

Abstract: Spherically symmetric spacetimes representing an anisotropic fluid and admitting a proper inheriting conformal Killing vector (ICKV) are studied and all such spacetimes are found. It is shown that the ICKV all lie in the (t,r)-plane except in the case of those solutions that are conformally flat, in which case there exist three angular-dependent ICKV. The physical properties of these solutions are investigated (with particular attention focused on static spacetimes), and, in the context of these solutions, examples are given which can be interpreted as stellar models (with reasonable physical properties), as models of magnetic fields in a plasma, and as models of viscous heat-conducting fluids. It is shown that global monopole solutions cannot admit a proper ICKV.

Method and methodology in feminist research: what is the difference?

Abstract: Feminism and nursing have historically travelled separate paths Nursinghas only recently begun to embrace feminist philosophy, and consequently nurse researchers are just beginning to undertake truly feminist research There appears to be little consensus between feminist researchers' interpretations of the concepts of method and methodology Prior to embarking on the development of a feminist research proposal it is imperative to differentiatebetween these two concepts This paper explores the concepts of method and methodology and explains their interrelationship Feminist research methodology, with its emphasis on a non-hierarchical, reflexive, interactive approach is highlighted and its impact on the researcher's choice of an appropriate method is discussed It is only through addressing these issues that nurseresearchers will be effective in pursuing truly feminist research that can act as a catalyst for the emancipation of women and the nursing profession

Great Lakes paleohydrology: Complex interplay of glacial meltwater, lake levels, and sill depths

Abstract: The oxygen isotope record of ostracode and clam shells recovered from Great Lakes cores of known age allows definition of times when meltwaters from the Laurentide ice sheet were important components of lake water in the several lake basins since 12 ka. We find that the lowstands in Lake Huron and Georgian Bay are characterized by isotopically light waters (δ 18 O values of -20‰ to -22‰ relative to SMOW [standard mean ocean water]) and the highstands by isotopically heavy waters of more local origin. These data can be used to determine the degree of hydraulic separation among the early Holocene lakes. Southern Lake Michigan, for instance, may mix with northern-source waters only during times of rising and high water levels. Generally it is characterized by waters of local origin.

Symptom differences in major depression, dysthymia, panic disorder, and generalized anxiety disorder.

Abstract: Objective The authors compared symptom features of specific subtypes of depressive and anxiety disorders. Methods Psychiatric outpatients with moderate levels of psychopathology and DSM-III diagnoses of major depression, dysthymia, panic disorder, or generalized anxiety disorder were given five standard measures of symptoms of anxiety and depressive disorders. Most of the outpatients were white, and most were middle-class. Results Principal components analysis revealed 12 orthogonal symptom components. Discriminant function analysis indicated that anxiety was distinguished by specific autonomic arousal symptoms, threat-related cognitions, and subjective anxiety and tension. Discriminant function analysis also indicated that depression was distinguished by anhedonia, cognitions of personal loss and failure, and dysphoric mood. Conclusions As nosological categories, major depression and panic disorder were better differentiated by specific symptom markers than dysthymia and generalized anxiety disorder.