9,185 research outputs found
More on the Narrowing of Impact Broadened Radio Recombination Lines at High Principal Quantum Number
Recently Alexander and Gulyaev have suggested that the apparent decrease in
impact broadening of radio recombination lines seen at high principal quantum
number n may be a product of the data reduction process, possibly resulting
from the presence of noise on the telescope spectra that is not present on the
calculated comparison spectra. This is an interesting proposal. However, there
are serious problems with their analysis that need to be pointed out. Perhaps
the most important of these is the fact that for principal quantum numbers
below n = 200, where the widths are not in question, their processed generated
profile widths do not fit the widths of the processed lines obtained at the
telescope. After processing, the halfwidths of the generated and telescope
profiles must agree below n = 200 if we are to believe that the processed
generated linewidths above n = 200 are meaningful. Theirs do not. Furthermore,
we find that after applying the linewidth reduction factors found by Alexander
and Gulyaev for their noise added profiles to our generated profiles to
simulate their noise adding effect, the processed widths we obtain still do not
come close to explaining the narrowing seen in the telescope lines for n values
in the range 200 < n < 250. It is concluded that what is needed to solve this
mystery is a completely new approach using a different observing technique
instead of simply a further manipulation of the frequency-switched data.Comment: Six pages with 4 figures. Accepted for publication in Astrophysics
and Space Scienc
Changes in the provision of physical education for children under twelve years. 1870-1992
A chronological survey over 120 years cannot fail to illustrate the concept of change, as history and change are intertwined and in some ways synonymous. Issues arising from political, social, financial, religious, gender and economic constraints affecting the practice and provision of Physical Education for all children under 12 in the state and independent sectors, including those with special needs are explored within the period. The chapter divisions are broadly determined by the Education Acts of 1870,1902,1918,1944 and 1988 to illustrate developing changes. The survey of relevant literature is followed by an introductory chapter outlining pre-1870 provision and practice, identifying pioneering efforts by physical educationalists to meet significant needs. Changes in the evolution of the subject are shown to reflect changes within contemporary society throughout the period of study. Chapters 2,3 & 4 span the period from 1870-1939 and trace the first official provision in elementary schools, the contest between military drill and Swedish gymnnastics, and the strong therapeutic element in Physical Education linking it to the School Health Service, A parallel development in the independent sector shows differing priorities. Chapter 5,covering World War II highlights in particular the impact of evacuation, which acted as a catalyst for reviewing provision and practice as a serious management consideration, Plowden's assessment of Physical Education in the Report on Primary Education,1967,halfway between the end of the war and the Education Act of 1988,is seen as a watershed between the cumulative effects of war, and the build up to massive reforms in the Acts of 1981(Special Needs)and 1988.The model of the independent sector becomes a target for legislation in State schools under Conservative administration. This is examined in Chapters 6 & 7,whilst Chapter 8 summarizes the legislation and subsequent Physical Education entitlement for all children. However, in conclusion, it is pointed out that legislative changes, incumbent on social historical progress, are also dependent on human and financial resources which are finite, and therefore need to be managed, in order to maximise present provision and practice, and as a basis for future planning
Planning in Hartford 1907 - 1942
A study of planning activities in Hartford, Connecticut from the creation of the first official planning agency in the United States in 1907, to 1942.
47 page
Alien Registration- Bell, Gordon D. (Fairfield, Somerset County)
https://digitalmaine.com/alien_docs/9699/thumbnail.jp
Two instructional units in business organization-how business is owned and relationship of government and business.
Thesis (Ed.M.)--Boston Universit
Nonlinear Instabilities in Chemical and Electrochemical Systems
This dissertation focuses on designing and manipulating nonlinear chemical and electrochemical reactions, with the aim of discovering new behaviors as well as gaining insights into their underlying mechanisms. In Chapter 2 the nonlinear behavior of the 4-aminophenol – bromate photoreaction was investigated from two directions. First, a second autocatalytic cycle was introduced through the incorporation of the metal catalyst cerium (IV). It was found that once the autocatalytic cycles were effectively balanced, complexity in the form of mixed mode oscillations was observed in a closed reactor. This dynamic behavior was successfully simulated using a modified model, which qualitatively reproduced the experimental results. It was also found that the precipitate which forms at the onset of the reaction of 4-aminophenol with bromate, N-bromo-1,4-benzoquinone-4-imine, could form a new bromate-based photochemical oscillator. In Chapter 3, the autocatalytic oxidation of 2-methyl-1,4-hydroquinone by acidic bromate lead to the discovery of a new photochemical oscillator. The system was found to be very sensitive to the intensity of illumination supplied, and complexity in the form of sequential oscillations was discovered using either ferroin or cerium (IV) as catalysts. Interestingly, cerium (IV) had a much more profound effect on the dynamical behavior, substantially lengthening the oscillatory period as well as being capable of inducing mixed-mode oscillations. Chapter 4 reports findings on the photosensitive 4-nitrophenol - bromate reaction. Extreme photo-inhibition was found to occur when illumination was supplied to the system whether in a stirred reactor or when being studied in a spatially extended system. Reaction diffusion experiments showed that under certain conditions long lasting complexity in the form of propagation failures took place. In Chapter 5, oscillations in both current density and potential were observed during the electro-oxidation of bromide ions. Interestingly, mechanistic findings suggest that the oscillations occurring during the oxidation of bromide ions on a platinum electrode belong to the type of oscillator referred to as Capacitance Mediated Positive Differential Resistance oscillator, and is the first solution based system to fit this class. In Chapter 6, the electro-oxidation of two sulfur compounds was seen to display nonlinear behavior. First, the oxidation of hydroxymethanesulfinate leads to oscillations in both current and potential on platinum or gold electrodes. The formation of an inhibiting layer was seen to have a substantial influence on the systems’ ability to support sustained oscillatory behavior. Electrochemical Impedance Spectroscopy showed that the oxidation of hydroxymethanesulfinate fits the class of an HN-NDR type oscillator. The oxidation of methionine only displayed nonlinear behavior on a gold surface, and only when operated under potentiostatic conditions. The oscillations were accompanied by gold dissolution and it was found that the electro-oxidation of methionine belongs to the N-NDR class. Two novel examples of utilizing nonlinear reactions towards application-based research is shown in Chapter 7. Here, the 4-nitrophenol – bromate oscillator is used to fabricate platinum nanoparticles, exploiting the dynamic bromide ion concentration to guide the growth of the noble metal nanocrystals. As an example of using an electrochemical nonlinear reaction, the gold dissolution occurring during the oxidation of methionine was found to lead to the fabrication of a Au nanoparticle modified electrode. This modified electrode was found to be capable of simultaneously detecting both hydroquinone and pyrocatechol in solutions containing both isomers, which is a significant improvement over regular Au electrodes
Influences of dietary polyunsaturated fatty acids on tissue fatty acid composition and eicosanoid production in Atlantic salmon (Salmo salar)
1. The literature has been reviewed with respect to the dietary intake and subsequent metabolism of polyunsaturated fatty acids (PUFA), of both the n-6 and n-3 series, in teleost fish. Particular emphasis has been made to the physiological roles of PUFA with respect to cell membrane function and eicosanoid production.
2. Atlantic salmon post-smolts were fed practical-type diets, based on fish meal, in three separate dietary experiments of 10-16 weeks duration. The first trial compared dietary lipid supplied either as fish oil (FO) or as sunflower oil (SO) with the diets having an n-3/n-6 PUFA ratio of 9.4 and 0.2 respectively. The second trial used diets formulated with blends of FO, SO, grape seed oil and safflower oil to provide linoleic acid at 10, 25 and 45% of total dietary fatty acids. The third trial was similar to the first but with an additional diet in which the lipid component was supplied by linseed oil (LO). All diets satisfied the nutritional requirements of salmonid fish for n-3 PUFA. There were no statistically significant differences in final weights between dietary treatments in the third trial. However, in the second trial fish fed the intermediate level of linoleic acid (25%) attained a significantly higher final weight compared to both other treatments while fish fed the highest level of linoleic acid (45%) had significantly lower final weights compared to both other treatments. In the first trial the effect of diet on growth (weight gain) could not be ascertained as the initial weights of the fish were significantly different.
3. A number of fish fed SO developed severe cardiac lesions which caused thinning of the ventricular wall and heart muscle necrosis. In addition the fish fed diets containing SO were susceptible to a transportation-induced shock syndrome that
resulted in 30% mortality.
4. Incorporation of linoleic acid (18:2n-6) into membrane phospholipids increased in response to dietary intake with fish fed SO having increased levels of 18:2n-6 (up to 15-fold), 20:2n-6 (up to 12-fold), 20:3n-6 (up to 25-fold) and arachidonic acid (AA; 20:4n-6) (up to 3-fold), and decreased levels of eicosapentaenoic acid (EPA; 20:5n-3) (up to 3-fold). The ratio of n-3/n-6 PUFA was decreased (up to 4-fold) and the20:4n-6/20:5n-3 ratio increased (up to 9-fold) in membrane phospholipids from fish fed SO compared to those fed fish oil. While the tissue phospholipids from fish fed La had increased levels of 18:2n-6, 20:2n-6 and 20:3n-6, the levels of AA, 22:4n-6 and 22:5n-6 were similar to or significantly reduced compared to fish fed FO. Membrane phospholipids from fish fed LO also had increased 18:3n-3 and 20:4n-3 compared to both other treatments while in some tissues and phospholipid classes EPA was increased compared to fish fed FO.
5. These dietary induced changes in phospholipid eicosanoid precursor ratio were reflected in altered eicosanoid production. In gill cells, stimulated with the calcium ionophore A23187, 12-hydroxy-8, 10, 14, 17-eicosapentaenoic acid (12-HEPE) was
the major 12-lipoxygenase product in fish fed Fa. In stimulated gill cells from fish fed SO and LO, 12-HEPE, 12-hydroxy-5, 8, 10, 14-eicosatetraenoic acid (12-HETE), 14- hydroxy-4, 7, 10, 13, 16, 19-docosahexaenoic acid (14-HDHE) and thromboxane B2 (TXB2) were all decreased compared to fish fed FO. However, the ratio of 12- HETE/12-HEPE was significantly elevated in stimulated gill cells from SO-fed fish compared to both other treatments. In stimulated blood leucocytes leukotriene B4 (LTB4)' 12-HETE and TXB2 were significantly increased while LTB5 and 12-HEPE
were significantly decreased in fish fed SO compared to those fed FO. Blood leucocytes from fish fed LO produced less TXB2 compared to fish fed SO and prostaglandin E2 was reduced compared to both other treatments. In isolated
cardiac myocytes stimulated with A23187, TXB2 production was increased in SO fed fish compared to those fed FO.
6. The activity of cardiac sarcoplasmic reticulum Ca2+-Mg2+ATPase was not affected by dietary treatment.
7. An established cell line derived from chum salmon heart (CHH-1) was utilised to study PUFA metabolism. The CHH-1 cells exhibited considerable A6 desaturase activity but showed no preference towards n-3 over n-6 PUFA. CHH-1 cells did exhibit significant A5 desaturase activity which showed a preference towards n-3 PUFA. No A4 desaturation activity was observed. Elongation of C20 PUFA was especially active in CHH-1 cells with C22 PUFA being specifically incorporated into phosphatidylethanolamine (PE) and phosphatidylserine (PS). CHH-1 cells supplemented with 20:3n-6 showed reduced growth rate, cell death and unusual pycnotic appearance, compared to those supplemented with other PUFA.
8. The lipid compositions of hearts and livers from wild and farmed parr and presmolts were analysed and compared. The fatty acid compositions of triacylglycerols (TAG) and phospholipids from both farmed parr and pre-smolts contained greater amounts of monoenoic fatty acids compared to their wild counterparts. TAG, phosphatidylcholine (PC) and PE from heart and liver of wild fish contained more 18:2n-6 and AA compared to farmed fish. Linolenic acid, EPA and 22:Sn-3 were increased in hearts and livers of wild fish compared to farmed. Docosahexaenoic acid (DHA; 22:6n-3) levels were higher in heart and liver of farmed fish, particularly in heart PC, PS and TAG. The n-3/n-6 PUFA ratio was generally lower in wild compared to farmed fish, largely due to higher n-6 PUFA, in particular AA, in wild fish.
9. The results are discussed with respect to the competitive interactions between PUFA of the n-6 and n-3 series which determine the fatty acid compositions of membrane phospholipids in salmon. The ratio of n-3/n-6 PUFA in membrane phospholipids, and in particular the ratio of AAIEPA, appears important in terms of membrane physiology and biochemistry, eicosanoid production and the development of cardiac histopathological lesions
Application of a portable FTIR for measuring on-road emissions
The objective of this work was the development of an onroad
in-vehicle emissions measurement technique
utilizing a relatively new, commercial, portable Fourier
Transform Infra-Red (FTIR) Spectrometer capable of
identifying and measuring (at approximately 3 second
intervals) up to 51 different compounds. The FTIR was
installed in a medium class EURO1 spark ignition
passenger vehicle in order to measure on-road
emissions. The vehicle was also instrumented to allow
the logging of engine speed, road speed, global position,
throttle position, air-fuel ratio, air flow and fuel flow in
addition to engine, exhaust and catalyst temperatures.
This instrumentation allowed the calculation of massbased
emissions from the volume-based concentrations
measured by the FTIR. To validate the FTIR data, the
instrument was used to measure emissions from an
engine subjected to a real-world drive cycle using an AC
dynamometer. Standard analyzers were operated
simultaneously for comparison with the FTIR and the
standard analyzer results showed that most pollutants
(NOx, CO2, CO) were within ~10% of a standard analyzer
during steady state conditions and within 20% during
transients. The exception to this was total HC which was
generally 50% or less than actual total HC, but this was
due to the limited number of hydrocarbons measured by
the FTIR. In addition to the regulated emissions, five
toxic hydrocarbon species were analyzed and found to
be sensitive to cold starts in varying proportions. Finally,
FTIR data was compared to results from a commercially
available on-road measurement system (Horiba OBS-
1000), and there was good agreement
Recent developments in the essential fatty acid nutrition of fish
Because of competitive interactions in the metabolism of polyunsaturated fatty acids, tissue and bodily requirements for each of the three dietary essential fatty acids in marine fish, 22:6n-3, 20:5n-3 and 20:4n-6, cannot be meaningfully considered in isolation. Rather, it is necessary to consider requirements in relative as well as absolute amounts, i.e. in terms of the ratio of 22:6n-3 : 20:5n-3 : 20:4n-6. This is illustrated by recent research in our laboratories which has suggested that the optimal dietary ratio of 22:6n-3 : 20:5n-3 in sea bass larvae is circa 2:1 with the optimal dietary ratio of 20:5n-3 : 20:4n-6 being circa 1:1. The optimal dietary ratio of 22:6n-3 : 20:5n-3 in turbot and halibut larvae is similarly circa 2:1 but the optimal dietary ratio of 20:5n-3 : 20:4n-6 in these species is 10:1 or greater. In addition, studies with salmon parr point to dietary 18:3n-3 and 18:2n-6 being important in determining the optimal tissue ratio of 20:5n-3 : 20:4n-6 for successful parr - smolt transition. We deduce that differences in essential fatty acid requirements for different species of fish reflect different dietary and metabolic adaptations to different habitats, and consider how such knowledge can be exploited to develop improved diets for fish, especially in their early stages of development
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