Measurement of forces between and within bilayers of neutral phospholipids

Phospholipids in water form lamellar phases made up of alternating layers of water and bimolecular lipid leaflets. Three complementary methods, osmotic, mechanical, and vapour pressures, were used to measure the work of removing water from lamellar phases composed of frozen dipalmitoylphosphatidylcholine ( DPPC ), melted DPPC, egg phosphatidylethanolamine or equimolar mixtures of DPPC and cholesterol ( DPPC/CHOL ), Concurrently the structural changes that resulted from this water removal were measured using X-ray diffraction. The work was divided into that which forces the bilayers together ( F ) and that which compresses the molecules together within the bilayers ( F )# A large repulsive force exists between bilayers composed of each of the lipids studied and this force increases exponentially as bilayer separation is decreased. F is affected by the nature of the head groups, conformation of the acyl chains and heterogeneity of these chains. In general all of the melted phosphatidylcholines ( melted DPPC, egg lecithin and DPPC/CHOL ) have large equilibrium separations in excess water resulting from large repulsive hydration forces between these bilayers. By comparison, egg PE has an increased attractive force, and frozen DPPC has a decreased hydration force; each results in smaller separations in water for these two lipids. The chemical potentials of the water between the bilayers for all these lipids lie on a continuum, indicating that interbilayer water cannot be characterized by two discrete states, usually referred to as "bound" or "non**bound". For all lipids studied a maximum of 25 % of the total work done on the system goes into deforming the bilayers. The method used here viii to separate repulsion from deformation, developed for us by v. A. Parsegian, provides a unique method for the measurement of lateral pressure of a bilayer and its modulus of deformability ( Y ). Lateral pressure is affected by the nature of the head group, conformation and heterogeneity of the acyl chains. For small changes in molecular surface area ( A ) near equilibrium, both melted and frozen DPPC have similar values for the deformability modulus. Thus in this regime it requires about the same force to change the angle of tilt of frozen chains as it does to compress the fluid bilayer. The introduction of cholesterol into bilayers of DPPC reduces dramatically the lateral pressure of the bilayers over a large range of molecular surface areas ( A ). The variation in the magnitude of bilayer repulsion with different phospholipids provides a basis for the mechanism of lipid segregation in mixed lipid systems and suggests that interacting heterogeneous membranes may influence or modulate the composition of the opposing membrane. The measurements of deformabilities of bilayers provides a direct comparison of them with the properties of monolayers.

The measurement of the optical absorption cross section of photosystem 1 and photosystem 2 from whole live cells of porphyridium cruentum, in light state 1 and light state 2

The optical cross section of PS I in whole cells of Porphyridium cruentum (UTEX 161), held in either state 1 or state 2, was determined by measuring the change in absorbance at 820nm, an indication of P700+; the X-section of PS2 was determined by measuring the variable fluorescence, (Fv-Fo)/Fo, from PS2. Both cross-sections were 7 determined by fitting Poisson distribution equations to the light saturation curves obtained with single turnover laser flashes which varied in intensity from zero to a level where maximum yield occurred. Flash wavelengths of 574nm, 626nm, and 668nm were used, energy absorbed by PBS, by PBS and chla, and by chla respectively. There were two populations of both PSi and PS2. A fraction of PSi is associated with PBS, and a fraction of PS2 is free from PBS. On the transition S1->S2, only with PBS-absorbed energy (574nm) did the average X-section of PSi increase (27%), and that of PS2 decrease (40%). The fraction of PSi associated with PBS decreased, from 0.65 to 0.35, and the Xsection of this associated PS 1 increased, from 135±65 A2 to 400±300A2. The cross section of PS2 associated with PBS decreased from 150±50 A2 to 85±45 A2, but the fraction of PS2 associated with PBS, approximately 0.75, did not change significantly. The increase in PSi cross section could not be completely accounted for by postulating that several PSi are associated with a single PBS and that in the transition to state2, fewer PSi share the same number of PBS, resulting in a larger X-section. It is postulated that small changes occur in the attachment of PS2 to PBS causing energy to be diverted to the attached PSi. These experiments support neither the mobile-PBS model of state transitions nor that of spillover. From cross section changes there was no evidence of energy transfer from PS2 to PSi with 668nm light. The decrease in PS2 fluorescence which occurred at this wavelength cannot be explained by energy transfer; another explanation must be sought. No explanation was found for an observed decrease in PSi yield at high flash intensities.

Measurement of growth in the lichen Rhizocarpon geographicum using a new photographic technique

Lichenologists and users of lichenometry have long used calipers or photogrammetry to measure the growth of crustose lichens. Now, digital photography and popular computer software provide methodological alternatives. This thesis developed and tested a new methodology for tracking change and growth of the lichen, Rhizocarpon geographicum. Adobe Photoshop CS3 Extended software and a photographic time series (1996,2003,2006 and 2007) were used to measure thallus diameter, area, prothallus width and areolae area in 115 small R. geographicum thalli (0.53-1049.88 mm2 ). Measures of 8 diameters per thallus showed that change in diameter was highly variable and is a weak index of growth. Thallus area was a reliable measure of growth (power correlation, R2 = 0.89). Rapid, highly irregular growth occurred in small thalli «30 mm2 ), and steady, uniform growth occurred in larger thalli (>30 mm2 ). This new methodology is tedious but can potentially generate accurate and precise measures for even the tiniest of lichens.

Aerobic exercise in adolescence : self-efficacy and stage of change

The purpose of this cross-sectional exploratory study was to examine the relationships among self-efficacy, stage of change, and exercise behaviour in a sample of younger (Grade 9) and older (Grade 12) adolescents. A secondary objective of this study was to apply the transtheoretical model of Stage of Change, as a measure of intention to change, in order to discover the applicability of the model to an adolescent cohort in relation to exercise behaviour. This five-stage model is a self-report measure of an individual's readiness to adopt a new behaviour (e.g., regular exercise). The transtheoretical model incorporates Bandura's self-efficacy factor, which is purported to be a predictive measure of exercise behaviour and a covariant of stage. Exercise behaviour was measured with the Physical Activity Scale, and the University of Rhode Island Change Assessment Scale (URleA) was used to measure the stage of change and self-efficacy variables. The results of this study indicated significant differences between younger and older adolescents, and between males and females in their exercise behaviour. No significant differences were found for grade and gender on stage of change as measured by either a single-item question or a continuous measure of stage. Although grade and gender subgroups were not significantly different in their self-efficacy, significant interaction was found in the grade*gender variable.

Brillouin spectroscopy : measurement of elastic and photoelastic constants of some alkali holide crystals

The assembly and testing of apparatus for the measurement of elastic and photoelastic constants by Brillouin scattering, using a Fabry-Perot interferometer and with argon ion laser excitation is described. Such measurements are performed on NaCI, KBr and LiF using the A = 488.0 nm laser line. The elastic constants obtained here are in very good agreement with the ultrasonic data for all three materials. The discrepancy between ultrasonic and hypersonic sound velocities which was reported by some authors for KBr and LiF is not confirmed, and the elastic constants obtained for LiF are the most accurate to date. Also, the present photoelastic constants are in good agreement with the data obtained by ultrasonic techniques for all three crystals. The results for the KBr and LiF crystals constitute the first set of photoelastic constants obtained for these materials by Brillouin spectroscopy. Our results for LiF are the best available to date.

Exploring the effects of change on nursing practice in acute ambulatory care settings : a qualitative study

As a result of the current changes taking place in the delivery of acute care services, the emergence of acute ambulatory care (AAC) settings is expanding. According to a literature review, the volume, acuity, and complexity of patient care in these settings is increasing while the time the patients spend under the care of nurses is decreasing. Two forces, hospital downsizing and advancing technology, are identified as the major contributors to the shift in acute care delivery. The effects that these changes are having on the clinical nursing practice of registered nurses working in AAC settings are not known. Given that AAC settings are rapidly expanding, it can be anticipated that the delivery of nursing care will continue to be compressed into a shorter time frame. Therefore, the following qualitative research question was formulated: What are the problems and issues related to clinical nursing practice in acute ambulatory settings? The purpose of this study was to explore the problems and issues associated with change and clinical nursing practice including the educational needs of nurses working in MC settings. Specific objectives of the study included the following: (a) to explore the problems and issues related to nursing practice in select AAC settings; (b) to explore the similarities and differences in perspectives related to role expectation between nurse managers, nurse educators, and staff nurses; and (c) to develop a conceptual framework that will guide the construction of an instrument needed for further research. This study used semistructured individual interviews and focus group sessions to collect data from the three categories of registered nurses. More specifically, data were collected from one nurse manager, two charge nurses, two nurse educators and fifteen staff nurses, working in three different MC settings of a major teaching hospital. Collected data were separately analyzed by the researcher and an external rater following grounded theory methodology. By using open and axial coding, the problems and issues identified by nurses were grouped into several major and minor themes. In final analysis, by using selective coding, the four core themes (intensification, moderation, frustration, and adaptation) were extracted. Each core theme was presented and discussed in relation to hospital downsizing and advancing technology. The relationships among the four core themes were discussed and depicted in a model termed the "Impact and Consequence Model on Nursing Practice in MC Settings." Implications for further research are discussed and research hypotheses, based on the research findings, are presented.

Exploring the experience of the pioneers of change

The world of work with Western society appears to be undergoing a major change. The literature has described this phenomenon as a change from an industrialbased economy to a knowledge-based economy. This change will represent a complete transformation of the world of work; some suggest that everything we have come to accept and know as normal will change. Our present society seems to be in a period of transition. It is a time with many challenges and problems, many of which cannot be solved with thinking patterns from an old industrial-based economy. A fundamental shift in thinking patterns consistent with a new emerging world of work must take place. This change in thinking represents a fundmental shift from traditional and linear ways of seeing the world (worldview), to more holistic ways of seeing the world. In this investigation the word paradigm was used to define how people see their world. A paradigm shift is defined as a change in how a person sees their world: a change from an old to new or different way of viewing the world. Those individuals who are the first to shift their paradigm are called paradigm pioneers. These individuals do not only shift their ways of seeing the world, but they also begin to act and behave in ways consistent with the new paradigm. Thus far the research literature has adequately described the concepts of paradigms and paradigm shifts. However, little is known regarding how people actually and eventually make a shift. As it will be important for each individual to make a personal paradigm shift, then it will be extremely valuable to learn more about the process itself. The purpose of this investigation was to explore these issues in more detail and specifically, describe the experience of paradigm shifts and explore the experience of paradigm pioneers. A qualitative research methodology involving in-depth interviews was used to investigate the experiences of four participants identified as paradigm pioneers. It is interesting to note that the participants in this study did not describe an allencompassing paradigm shift. In fact, each participant, defined a paradigm shift in several different ways. They did relate several examples of paradigm shifts. However, even among these examples, there was a high degree of variability. The findings of this investigation centered upon the participants' experience as pioneers. Each pioneer shared many of the same qualities, the first quality of which described how these pioneers dealt with change. I called this a change-sense quality. The pioneers viewed change in an open and positive manner, and were also aware of change taking place in their world. Finally, they displayed an understanding of change, and a bias to take positive action in the face it. The participants also shared an inner quality. The four pioneers demonstrated a personal purpose and vision, and were selfdirected individuals. They also had an innate curiosity which translated into a love of learning. They also displayed a quality where relationships with others were highly valued. Relationships were important to the pioneers because they played a support role to help them deal with the challenges of being a pioneer. Pioneers also valued relationships because, they relied on others to make change happen. The above mentioned qualities enabled pioneers to be effective in a changing world of work. The findings from this investigation have many implications for research and practice. First, the concept of paradigms and paradigm shifts must be further researched. A great deal more must be learned in order to better understand the kind of shift individuals must make to be effective in the new world of work. Second, the qualities displayed by pioneers are important for all members of the world of work to develop. The qualities shared by pioneers appeared to represent an enduring set of traits that can possibly help individuals deal more positively with uncertainty and rapid change taking place in today's North American world of work.

Measurement of repulsive forces between charged phospholipid bilayers

Electrostatic forces between membranes containing charged lipids were assumed to play an important role in influencing interactions between membranes long before quantitative measurements of such forces were available. ~ur measurements were designed to measure electrostatic forces between layers of lecithin charged with lipi~s carrying ionizable head groups. These experiments have shown that the interactions between charged lipid bila.yere are dominated by electrostatic forces only at separations greater than 30 A. At smaller separations the repulsion between charged bilayers is dominated by strong hydration forces. The net repulsive force between egg lecithin bilayers containing various amounts of cherged lipids (phosphatidylglycerol (PG) 5,10 ano 50 mole%, phosphatidyli. nosi tol (PI) 10 mole% and sodium oleate (Na-Ol) 3,5 and 10 mole%, where mole% gives the ratio of the number of moles' of .charged lipid to the total number of moles of all lipids present in the sample) was stuoied with the help ('If the osmotic streas technique described by LeNeveu et aI, (1977). Also, the forces between pure PG were j_nvestigated in the same manner. The results have been plotted showing variation of force as a function of bilay- _ er separation dw• All curVes 90 obtained called force curves, were found to be similar in sha.pe, showing two distinct regions, one when dw<.30 A is a region cf very rapid iiivariation of force with separation ( it is the region dominated by hydre,tion force) and second when dw> 40 A is a region of very slow variation of force with separB.tion ( it is the region dominated by the electrostatic force). Between these two regions there exists a transition area in which, in most systems studied, a phase separation of lipids into fractions containing different amounts of charged groups, was observed. A qualitative analysis showed that our results were v/ell described by the simple electrostatic double -le.yer theory. For quantitative agreement between measured and calculated force curves however, the charge density for the calculations had to be taken as half of that given by the number density of charged lipids present in the lecithin bilayers. It is not clear at the moment what causes such low apparent degree of ionization among the charged head groups, and further study is needed in this area.

Non-invasive measurement of trigeminal nerve somatosensory evoked potentials

Whiplash injuries are common yet enigmatic to substantiate clinically. Trigeminal somatosensory evoked potentials (TSEPs) were posited as an indicator of trigeminal nerve conduction damage resulting from whiplash. Alternating polarity square-wave current stimuli were applied transcutaneously in the facial region. 379 recorded pilot trials from 27 participants (8 male and 19 female) were utilized to develop a non-invasive recording capability for TSEPs. Stimulus intensity and artifact, cortical recording sites, stimulation electrode design and placement were explored. Statistically significant differences in amplitude of TSEP waveform components at 13, 19 and 27 ms between uninjured and whiplashed participants were noted. Increased stimulus intensity in whiplashed participants was observed to increase TSEP amplitude. The present methodology and hardware are discussed and directions for future advancement of the current process are outlined.

Notice of Change in Reparation Agent- Quebec 1 May 1822

A notice of change in reparation agent between Robert Morrogh and Thomas Douglas from Quebec to Daniel Shannon in Niagara.

Receipt from E. Priddle for measurement of slate roof

Receipt from E. Priddle for measurement of slate roof, June 24, 1876.