Laboratory studies of photodissociation processes relevant to the formation of cometary radicals

The strength of the C2(d 3 Pi g yields a 3 Pi u) Swan band emission in the spectra of cometary comae identifies this species as a prominent constituent of the coma gas. It was previously suggested that the formation of cometary C2 proceeds via the secondary photolysis of the C2H radical. The detection of C2H in the interstellar medium and the recent analysis of the radial variation in C2(delta V=O) surface brightness of Comet Halley support the postulate that C2 is a third-generation molecule. Measurement of the C2 and C2H translational energy distributions produced from the multiphoton dissociation (MPD) of acetylene at 193 nm are identified . Time-resolved FTIR emission studies of the nascent C2H radical formed in the C2H2 yields C2H + H reaction verify that this species is produced both vibrationally and electronically excited. A survey of the internal energy distributions of the C2 fragments produced from the MPD of acetylene using a high intensity ArF laser is currently in progress in the laboratory. Recent experiments have focused on the measurement of rotational energy distribution for the C2(A 1 Pi u, a 3 Pi u) fragments. The C2(a 3 Pi u) detection capability is currently being improved by performing this experiment in a molecular beam, thus allowing for discrimination between initial emission and laser-induced fluorescence (LIF). Although the experiments performed to date provide considerable evidence in support of C2H yields C2 + H reaction, there is an important distinction to be made when comparing the laboratory conditions to those typically found in comets. The C2H radicals generated in the laboratory experiments are formed vibrationally and/or electronically excited. Any rotationally/vibrationally excited C2H present in cometary comae will quickly undergo radiative relaxation in the infrared to their lowest rotational and vibrational state. Experiments are currently under way to confirm the cometary formation of C2 via the VUV dissociation of cold C2H

Vegetative Propagation of Green Ash by Softwood Cuttings

Because of the devastation caused by Dutch Elm Disease to American elm an expanding avenue of. research is the quest for a replacement for the elm. Since green ash is native throughout Eastern United States and Great Plains, is easy to transplant, and grows rapidly while young, increased emphasis has been placed on this tree as a possible replacement. Green ash is the most widely ranging of American ashes. It develops into a small to medium-sized tree with a broad, irregular crown. It is exceptionally cold and drought hardy and once established will persist. It is necessary to use vegetative propagation to produce selected, improved trees of green ash. Vegetative propagation of green ash has several advantages over reproduction by seeds. Asexually propagated trees often attain a usable size more rapidly and produce a higher percentage of salable stock than do trees started from seed. Asexual propagation is also essential if superior growth rate, form, and disease and insect resistance are to be insured. Moreover, it enables selection for staminate flowering or male trees, which is desirable in order to prevent promiscuous seeding that results with pistillate flowering, female trees. Nevertheless, it should be pointed out that vegetatively propagated plants do have the disadvantage of perpetuating disease; thus, clean stock is of the utmost importance. Seedling rootstocks used in budding and grafting are variable and may modify the plant to such an extent that it is difficult to determine the selection\u27s value. Furthermore, cuttings are preferred in order to circumvent problems that may arise with stock-scion incompatibility or with poor graft unions. Grafted or budded plants show additional difficulties. Rootstocks often sprout, and some plants tend to sucker heavily from basal regions after the trees have reached salable size. Cuttings are often less expensive and may be more rapidly and simply produced. This study assesses the ability of softwood cuttings from several selected trees of green ash to produce roots, to initiate new growth, and to survive the winter in containers. Further, it tests the relative rooting capacity of softwood cuttings taken from several species of ash. Factors which affect the rooting response of plants were investigated in respect to their importance in rooting green ash. Factors explored were length of cutting, type of cutting (node, internode, or heel from terminal shoots), stump sprouts, blanching, clonal variations, girdling, length of rooting period, hormones, hormonal concentrations, and juvenility

Using Transcendental Phenomenology to Explore the “Ripple Effect” in a Leadership Mentoring Program

Several approaches exist for organizing and analyzing data in a phenomenological qualitative study. Transcendental phenomenology, based on principles identified by Husserl (1931) and translated into a qualitative method by Moustakas (1994), holds promise as a viable procedure for phenomenological research. However, to best understand the approach to transcendental phenomenology, the procedures need to be illustrated by a qualitative study that employs this approach. This article first discusses the procedures for organizing and analyzing data according to Moustakas (1994). Then it illustrates each step in the data analysis procedure of transcendental phenomenology using a study of reinvestment or the “ripple effect” for nine individuals who have participated in a youth leadership mentoring program from the 1970s to the present. Transcendental phenomenology works well for this study as this methodology provides logical, systematic, and coherent design elements that lead to an essential description of the experience

Cometary implications of the internal energy distributions of the C2 and C3 radicals produced in the photolysis of the C2H and C3H2

The C2 and C3 radicals are prominent emission in the visible region of cometary spectra. Observational evidence exists that suggests these radicals are formed as granddaughter fragments in the photolysis of more stable molecules. Likely candidates for these parent molecules ar C2H2, C3H4 (allene), and CH3C2H (propyne). Recent laboratory studies were performed on all of these parent molecules and they indicate that they can indeed produce the observed cometary radicals. In the case of C2H2, the laboratory evidence suggest that C2 is formed via the following mechanisms: (1) C2H2 + photon(193 nm) yields C2H + H; and (2) C2H + photon(193 nm) yields C2 + H. Evidence is presented to show that the C2 radical produced in the second reaction occurs in a variety of electronic, vibrational, and rotational states. It is argued that this is a result of conical intersections in the potential energy curves and the density of states associated with these curves. Since this is a property of the C2H radical similar initial product state distributions are expected to occur in comets. This means that any models of the C2 emission may have to start off with rotationally excited C2 radicals in both the singlet and the triplet manifolds. When C3H4 (allene) and CH3C2H (propyne) were photolyzed, the C3 radical is formed. In the allene case, laboratory evidence shows that the C3 radical is formed via the following mechanism: (1) C3H4 + photon(193 nm) yields C3H2 + H2; and (2) C3H2 + photon(193 nm) yields C3 + H2. More C3 is formed in the case of allene than in the propyne case, even though the absorption cross section for propyne is a factor of 2 larger. This suggests that competing dissociation pathways are present during the photolysis of propyne that are not available to allene. The observed quantum state distributions of the C3 product were the same for both parent molecules, indicating that the same intermediate state is involved. These observations can be understood if the excited propyne formed in the initial absorption step isomerizes to excited allene before it dissociates to the same daughter compound. This postulate was tested by comparing RRKM calculations of the isomerization rate of excited propyne versus the decomposition rate to other products

Cometary implications of recent laboratory experiments on the photochemistry of the C2H and C3H2 radicals

Recent laboratory results on the photodissociation of the C2H and C3H2 radicals are described. These studies show that the C2 and C3 radicals are produced by the 193 nm photolysis of the C2H and C3H2 radicals, respectively. The quantum state distributions that were determined for the C2 radicals put certain constraints on the initial conditions for any models of the observed C2 cometary spectra. Experimental observations of C2 formed by the 212.8 nm photolysis of C2H are used to calculate a range of photochemical lifetimes for the C2H radical

MEMS 411: Mini-Golf Robot

The following report details the design and construction of a mini-golf robot overthree months. The robot was designed under the standards provided by theASME Fall 2023 Design Challenge. The robot would need to traverse the mini-golfcourse, completing it in under 10 minutes with the assistance of an attached strikermechanism. It was necessary that the robot could position itself precisely withrespect to the goofball, while also staying stationary while striking the object. Therobot design timeline followed the guidelines of the engineering design process, withconcept generation, concept selection, prototype embodiment and design refinementall playing important roles in ensuring the design of the vehicle was best suited tothe goals it was supposed to complete. The final prototype performance goals ofthe vehicle, determined by our customer, Dr. J. Jackson Potter, were for the deviceto a) climb over a long wooden board that is 3.5” tall and 1.5” thick, b) climb onto,over, and back down from a sheet of 1/2”-thick plywood whose bottom surfaceis 3.5” above the ground, and c) position itself next to three golf balls (withoutdisturbing them) and ”aim” in a specified direction before removing the ball andcontinuing to the next ball in ¡ 1 minute, all while carrying extra weight in theshape of a wooden striker template. The group was able to complete prototypegoal number 3 successfully but failed to complete prototype goals 1 or 2. Thisreport outlines the full process of the creation and assembly of the vehicle

An appraisal of methods to increase generalisabilty of economic evaluation of pharamaceuticals

SIGLEAvailable from British Library Document Supply Centre- DSC:DXN056766 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Stabilitet i hengebreer med henblikk på isskred : eksempel fra Steindalsnosi, Sognefjellet, Vest-Norge

Stabiliteten i hengebreer avhenger av tre sentrale faktorer. Helningen på underlaget til breen, temperaturen i bakken rundt breen og temperaturen i selve breen. Det er forsøkt å kartlegge disse faktorene for Nedre Steindalsbre i Vest-Jotunheimen med diverse metoder. GPR, BTS, MTD og borehullstemperatur har stått sentralt i disse undersøkelsene. Stabiliteten avgjøres ved klare grenser for isskred etter en empirisk sammenheng mellom temperaturen i bakken, breen og helningen på underlaget. Denne er satt til 45 grader for polytermale breer med permafrost i underlaget, og 25 grader for tempererte breer uten bermafrost i underlaget

The temporal changes in the emission spectrum of Comet 9P/Tempel 1 after Deep Impact

The time dependence of the changes in the emission spectra of Comet 9P/Tempel 1 after Deep Impact are derived and discussed. This was a unique event because for the first time it gave astronomers the opportunity to follow the time history of the formation and decay of O(1S), OH, CN, C2, C3, NH, and NH2. Least squares fits of a modified Haser model with constraints using known rate constants were fit to the observed data. In the case of OH a simple two-step Haser model provides a reasonable fit to the observations. Fitting the emissions from O(1S), CN, C2, C3, NH, and NH2 requires the addition of a delayed component to a regular two or three step Haser model. From this information a picture of the Deep Impact encounter emerges where there is an initial formation of gas and dust, which is responsible for the prompt emission that occurs right after impact. A secondary source of gas starts later after impact when the initial dust has dissipated enough so that solar radiation can reach the surface of freshly exposed material. The implications of this and other results are discussed in terms of the implications on the structure and composition of the comet's nucleus.Comment: Accepted for publication in The Astrophysical Journal; 26 pages including 8 figures and 1 tabl

”Nå sitter vi og motsier oss selv" - Reproduksjon av skolepolitiske diskurser i matematikklæreres refleksjoner rundt undervisningspraksis : en diskursanalyse av matematikklæreres refleksjoner rundt valg av undervisningspraksis i lys av en flerfoldig skolepolitisk diskursorden

I denne teksten presenterer jeg en undersøkelse av hvordan skolepolitiske diskurser reproduseres og omformes i matematikklæreres refleksjoner rundt valg av undervisningspraksis. Dette gjøres med en sosialkonstruksjonistisk forståelse av at diskurser, som forskjellige måter å bruke språket på, konstituerer sosiale virkeligheter og på denne måten påvirker valg av handling. Oppgaven stiller forskningsspørsmålene: Hvordan reproduseres og omformes skolepolitiske diskurser i matematikklæreres refleksjoner rundt valg av undervisningspraksis? Og, hvordan bruker matematikklærere skolepolitiske diskurser i sine refleksjoner rundt valg av undervisningspraksis? For å besvare disse spørsmålene undersøkes interdiskursiviteten mellom skolepolitiske diskurser og matematikklærernes diskurser, ved hjelp av Faircloughs kritiske diskursanalyse slik den blir presentert av Winther Jørgensen & Phillips (1999), og Faircloughs & Faircloughs (2012) analyseverktøy av politiske diskurser som argumenterende for valg av handling. De skolepolitiske diskursene struktureres i en diskursorden bestående av tre skolepolitiske diskurser (kvalitetsdiskursen, dannelsesdiskursen og enhetsskolediskursen). Denne diskursordenen eksemplifiseres og konkretiseres ved diskursanalyse av utvalgte utdrag fra St. Meld. nr 31 (2007-2008) og St. Meld. nr 20 (2012-2013). Deretter analyseres utdrag av tekst produsert i en fokusgruppesamtale med tre matematikklærere, i lys av den skolepolitiske diskursordenen. Funnene viser at alle diskursene innen diskursordenen, i ulik grad reproduseres i matematikklærernes refleksjoner. Diskursene omformes også som hybriddiskurser. I enkelte tilfeller konfronterer skolepolitiske diskurser hverandre som motstående diskurser. Disse tilfellene ser ut til å skape dilemmaer for matematikklærerne, eller en opplevelse av selvmotsigelse.Master i skolerettet utdanningsvitenska