Reverse Transfers Research Articles

Postbaccalaureate Reverse Transfers in Maryland and Tennessee: Institutional Problems and Possibilities

AbstractThe growing enrollment of baccalaureate degree holders at two‐year colleges, as illustrated in studies conducted in Maryland and Tennessee, offers potential institutional problems as well as benefits.

Bachelor's Degree Students Attending Community Colleges: A Look at Postbaccalaureate Reverse Transfers in Missouri

AbstractThis chapter details the results of a study of postbaccalaureate reverse transfers attending community colleges in Missouri.

Singlet and Triplet State Back Electron Transfer from Photogenerated Radical Ion Pairs Studied by Time-Resolved CIDNP

Radical ion pairs are generated in acetonitrile solution by photoinduced electron transfer from naphthalene derivatives to cyanobenzenes and undergo reverse electron transfer to the singlet ground and to excited triplet states of the parent compounds. Both pathways lead to chemically induced nuclear polarization of the ground state products. They can be separated because the triplet contribution appears delayed by the triplet lifetime. Variation of the radical pair energy leads to a dominance of either the singlet or triplet channel. The analysis of the absolute net CIDNP effects and their time dependencies yields reaction probabilities for the reverse electron transfers which depend on the appropriate energy gaps as described by the Marcus theory, as well as rate constants for degenerate electron and spin exchange processes. For the donor/acceptor system naphthalene/(E)-1,2-dicyanoethene, the triplet pathway is also found dominant.

On the representation of backscatter in dynamic localization models

The dynamic localization model is a recently developed method that allows one to compute rather than prescribe the unknown coefficients in a subgrid scale model as a function of position at each time-step. A realistic subgrid scale model should describe both the direct and reverse (backscatter) energy transfers at the local level. A previously developed dynamic localization model accounted for backscatter by means of a (deterministic) eddy viscosity that could locally assume positive as well as negative values. Here this paper presents an alternative stochastic model of backscatter in the context of the dynamic procedure. A comparative discussion of the merits of stochastic versus deterministic modeling of backscatter is presented. These models are applied to a large eddy simulation of isotropic decaying and forced turbulence. Tests are also performed with versions of the model that do not account for backscatter. The results are compared to experiments and direct numerical simulation. It is shown that the models correctly predict the energy and three-dimensional (3D) energy spectra in decaying turbulence. In the forced case the Kolmogorov 5/3 law seems better predicted by models accounting for backscatter. A relative evaluation of the various versions of the model in terms of predictive capability and cost is provided.

Photochemistry of intercalated methylene blue: photoinduced hydrogen atom abstraction from guanine and adenine

Methylene blue intercalates more effectively into poly[dGdC] (K = (1.6 [+-] 0.4) [times] 10[sup 6] M[sup [minus]1]) than poly[dAdT] (K = (1.6 [+-] 0.5) [times] 10[sup 4] M[sup [minus]1]); in the latter case, intercalation competes with surface binding (K = (2.3 [+-] 0.6) [times] 10[sup 4] M[sup [minus]1]). Intercalation is accompanied by a dramatic reduction in the lifetime of the first excited singlet state, causing decreases in quantum yields for both fluorescence and formation of the triplet state. In the case of methylene blue intercalated into poly[dGdC], transient absorption spectroscopic measurements have shown that the excited singlet state of the dye abstracts a hydrogen atom (or an electron) from an adjacent nucleic acid base, presumed to be guanine on thermodynamic grounds. The rate constants for forward and reverse transfers, respectively, are (2.5 [+-] 0.3) [times] 10[sup 11] and (3.3 [+-] 0.4) [times] 10[sup 10] s[sup [minus]1]. The rate constant for the forward transfer in poly[dAdT] is (1.4 [+-] 0.5) [times] 10[sup 10] s[sup [minus]1] and is presumed to be slower than that of the reverse transfer. Using thermodynamic arguments, it is concluded that the quenching processes involve hydrogen atom transfer from guanine or adenine to the excited singlet state ofmore » methylene blue. 48 refs., 4 figs.« less

Properties of activation barriers from thermal rate data on forward and reverse reactions: hydroxyl + hydrogen, amidogen + hydrogen, methyl + hydrogen and methyl + hydrogen chloride

Experimental data on the temperature dependence of forward and reverse transfers of hydrogen atoms have been assembled. The following transition-state theory (TST) expressions, incorporating a factor, {kappa}, for tunneling through a one-dimensional Eckart barrier of effective forward and reverse heights E{sub f} and E{sub r} and of characteristic tunneling temperature, T*, were fitted by least-squares methods to the data for each reaction. For the reactions OH + H{sub 2} {r equilibrium} H{sub 2}O + H and NH{sub 2} + H{sub 2} {r equilibrium} NH{sub 3} + H, most standard deviations are from 1% to 3% of the parameter values and the parameters agree well with independent quantum chemical or thermochemical estimates. For the reactions CH{sub 3} + H{sub 2} {r equilibrium} CH{sub 4} + H, E{sub f} - E{sub r} disagrees with the values from the thermochemical tables, suggesting that there are errors in these tables or errors of 1 order of magnitude in the low-temperature rate constants.

Defunding Latin America: Reverse transfers by the multilateral lending agencies

Defunding Latin America: Reverse transfers by the multilateral lending agencies

An Indirect Test of Children's Influence on Efficiencies in Parental Consumer Behavior

A statistical test is applied to explore the possibility that children can affect the efficiency with which parents consume. Parents may receive some economic benefits from children in the form of reverse integenerational transfers that occur because of a positive influence children have on family behavior. Results show that not only do children have an influence on parental consumption, but also that the influence is beneficial. In fact, not accounting for such a benefit could cause an underestimate in such measures as the rate of return to education or the benefits from such governmental programs as Head Start.

AN UPDATE ON REVERSE TRANSFERS TO TWO‐YEAR COLLEGES

Reverse transfers, students who transfer from four‐year to two‐year colleges, now make up 20% of the two‐year college enrollment. This paper will describe reverse transfers in terms of demographics, educational goals, and academic performance. Data from thirteen two‐year colleges includes official student records on a 1984 class of newly enrolled students and a survey of this same cohort. Reverse transfers differ significantly from two‐year natives in terms of race and other demographic characteristics. Reverse transfers were older, more likely to be married, employed full‐time, and had higher socioeconomic status indicators. Reverse transfers’ parents were more likely than native students’ to have earned a college degree. Two‐year students who had already earned a college degree had short‐term occupational goals aimed at upgrading job skills or making themselves more employable. Those who had not yet earned a degree were most likely to aspire to the bachelors degree. Reverse transfers earned significantl...

Pleioxenous host-restriction in fleas

A review of the pleioxenous genera of fleas, those genera whose species are confined to hosts of a single family, indicates that such a restriction results from one of several situations. Genera of 10 or more taxa (species and subspecies) were considered, so as to exclude very small genera that might be relicts. Polyxenous genera, whose species occur regularly on two or more families (and frequently on two or more orders) of hosts are far more numerous than pleioxenous genera. Bat fleas (Ischnopsyllidae) are unique in that all genera are pleioxenous. This seems to reflect the fact that most bat fleas occur on cave-dwelling bats, and that the cave provides for larval development of bat fleas. Five pleioxenous genera occur on rodents in deserts or semiarid regions. The extreme climatic changes that have been concomitant with desertification from the Mid-Cenozoic, and especially in the Pleistocene, are paralleled by the proliferation of the mammalian hosts themselves in deserts. Three pleioxenous genera are found on fossorial rodents (Geomyidae). These rodents appear to have been isolated and rejoined during climatic changes in western North America; and rapid speciation of their fleas followed speciation of the hosts. One pleioxenous genus, and others that are nearly pleioxenous, parasitize cricetine mice in Central America. It is suggested that the Cenozoic archipelago which occupied this region provided an environment for rapid speciation of both hosts and their fleas. Two pleioxenous genera are found on tree squirrels in the tropics. Although fleas of mice occasionally make permanent transfers to squirrels, as the former occupy squirrel nests, reverse transfers (from tree squirrels to mice) are rare. Two genera of fleas are restricted to murid mice in Africa south of the Sahara; this is a region in which murid mice usually outnumber species of other rodent families. One pleioxenous genus occurs on Arvicolidae, possibly a result of rapid speciation of hosts during the extreme climatic changes in boreal habitats during late Cenozoic and Pleistocene. There is a tendency for the apparently more ancient families of fleas (e.g. Stephanocircidae, Pygiopsyllidae and Hystrichopsyllidae) to have very few pleioxenous genera but many polyxenous genera. The more modern families of fleas (e.g. Leptopsyllidae and Ceratophyllidae) contain a higher percentage of pleioxenous genera.

COMPARATIVE STUDY OF REVERSE TRANSFER, LATERAL TRANSFER, AND FIRST‐TIME COMMUNITY COLLEGE STUDENTS

Among the “new” students attending community colleges are a large number of reserve and lateral transfers, students with previous college experience. This study was conducted to provide information on their characteristics and their reasons for attending and leaving colleges as compared to the first‐time college study. A sample of 10,196 students in the Los Rios Community College District (California) was studied and five student groups were identified: First Time Students (FTS), 54.7 percent; Noncompleter Lateral Transfers (NCLT), 19.2 percent; Completer Lateral Transfers (CLT), 7.5 percent; Noncompleter Reverse Transfers (NCRT), 12 percent; Completer Reverse Transfers (CRT), 7.6 percent. The CRT and FTS groups differed most significantly. The CRT were older, more often married with children, worked more hours, and were taking fewer units. In general, the characteristics of the other three groups were similar and at a mid‐point between the CRT and FTS. Factor analysis of the reasons for attending showed ...

Proton transfers between first- and second-row atoms: (H2OHSH2)+ and (H3NHSH2)+

A b initio molecular orbital methods are used to study the transfer of the central proton along the hydrogen bonds in (H2OHSH2)+ and (H3NHSH2)+. Proton transfer potentials are generated using the 4-31G* basis set at the Hartree–Fock level for various values for the hydrogen bond length R(XS). Full geometry optimizations are carried out at each stage of proton transfer. The barrier to proton transfer increases as the hydrogen bond is lengthened. For a given bond length, the highest barriers are observed for transfer from N to S and the smallest for the reverse process. Intermediate between these two extremes are transfers between O and S for which the forward and reverse transfers lead to nearly identical barrier heights. Adiabatic transfers, in which the intermolecular separation is allowed to change as the transfer progresses, are studied as well. The barrier to adiabatic transfer from OH2 to SH2 is 2.6 kcal/mol; 1.9 for the reverse process. Similar relaxation of R(NS) leads to no stable (NH3)(SH3)+ structure and hence transfer from N to S is not expected. Application of larger basis sets and inclusion of correlation effects through second and third-order M≂ller–Plesset corrections support the reliability of the HF/4-31G* results.

REVERSE TRANSFERS WHO RETURN TO A UNIVERSITY: AN ANALYSIS OF THEIR ACADEMIC PROGRESS

Northern Illinois University was the site of a study of reverse transfer students returning to a university. The 269 students in the study represent 15% of all the transfer students entering the university during 1975‐1976. Their 4?2?4 academic progress found 45% had academic difficulty in their initial senior institution. In the community college, 55% completed an associate degree. The academic‐difficulty students raised their average GPA by 1.4 points. Five years after entering NIU the reverse transfers had a bachelor's degree completion rate of 61.3%. Students in previous academic difficulty attained a 55.4% graduation rate while students in good standing in their initial senior institution had a 66.2% graduation rate. Among students in previous academic difficulty, students who were attending a different senior institution were twice as likely to complete a bachelor's degree than students returning to the same school where they had had academic problems previously. A discriminant analysis of NIU statu...

Influence of acid on the photoredox reaction between tris(2,2′-bipyridyl)ruthenium(II) and iron(III)

Photoreaction between (bipy)3Ru2+(1) and iron(III) leads to efficient, reversible electron transfer. The rates of forward and reverse electron transfers are somewhat dependent upon the structure of the iron species. The forward reaction is fastest with the simple hydrated iron(III) ion but the reverse reaction is fastest when the iron(III) species is a negatively charged complex ion. Also, the concentration of acid is important and high concentrations of perchloric and trifluoromethyl-sulphonic acids yield the highest steady-state yield of redox products.

Suppressor T Cell Mechanisms in Contact Sensitivity

Abstract We investigated mechanisms of suppression of contact sensitivity to DNFB in mice. In particular, we studied the suppression produced by suppressor T cells which had been induced by injection of syngeneic DNP-modified lymphoid cells (syninduced Ts). Syninduced Ts were found by several criteria to inhibit the efferent limb of sensitivity by inhibiting the expression of LN cells from DNFB-sensitized animals. First, syninduced Ts can suppress previously sensitized recipients in an antigen-specific manner. Second, co-transferred syninduced Ts could block the passive transfer of contact sensitivity by DNFB-immune LN cells given to normal recipients. This inhibition was shown to be dose dependent, antigen specific, and non-MHC restricted. Third, in reverse transfers of sensitized cells into tolerant recipients, only those recipients containing active syninduced Ts could inhibit the expression of sensitivity by the passively transferred immune T cells. In contrast, syninduced Ts were incapable of inhibiting the afferent limb of the response as assessed by the normal, post-sensitization DNA synthetic response of draining LN cells in Ts recipient mice. Syninduced Ts were not inhibitable by prior treatment with anti-TNP antiserum, indicating a lack of surface-associated tolerogen. The locus of suppression was most clearly shown in experiments where mice received syninduced Ts at the same time they were sensitized. These mice were themselves unresponsive, but did contain immune lymphoid cells able to express contact sensitivity after transfer to normal recipients followed by DNFB challenge. The data suggest that the suppressive environment allows the development of a normal complement of DNFB-specific immune T cells, but inhibits the expression of this sensitivity. The data are discussed in terms of current models of suppression, and are compared with mechanisms of suppression in other contact sensitivity models.

The Political Economy of Development and Underdevelopment

Part 1 Theory and method in economic development: development - which way now?, Amartya K. Sen the misconceptions of developmental Deepak Lal conventional foolishness and overall ignorance - current approaches to global transformation and development, Gerald Helleiner toward a non ethnocentric theory of development - alternative conceptions from the Third World, Howard H. Wiarda. Part 2 Economic development and underdevelopment in a historical perspective: capitalism, Dudley Dillard on the political economy of backwardness, Paul A. Baran the development of underdevelopment, Andre Gunder Frank perspectives on underdevelopment, Frank, the modes of production school, and Amin, David F. Ruccio, Lawrence H. Simon plant imperialism, Lucile Brockway the modernization of underdevelopment - El Salvador, 1858-1931, E. Bradford Burns. Part 3 Development, democracy and contemporary international institutions: revolution in Easten Europe, Andre Gunder Frank options for tacking the external debt problem, Robert Devlin defunding Latin America - reverse transfers by the multilateral lending agencies, Richard E. Feinberg. Part 4 Agriculture in development: in search of a development paradigm, Gene Ellis the new development economics, Joseph E. Stiglitz the peasant economy, Alexander Schejtman the political economy of Third World food imports, Derek Byerlee. Part 5 Industry in development: industry and underdevelopment reexamined, R. B. Sutcliffe global feminization through flexible labour, Guy Standing the political economy of privatization in developing countries, Henry Bienen, John Waterbury can the rest of Asia emulate the NICs, Clive Hamilton the state and industrial strategy, Helen Shapiro, Lance Taylor. Part 6 The human dimension of development: the human dilemma of development, Denis Goulet, Charles Wilber survival strategies and power amongst the poorest, Tony Beck into another jungle - the final journey of the Matacos, Ariel Dorfman women and rural development policies, Deniz Kandiyoti what really matters - human development, Peter Gall. Part 7 What is to be done?: development.. .or liberation, Denis Goulet pedagogy of the oppressed, Paulo Freire human development, Keith Griffin, John Knight the arms race and development, Inga Thorsson conserving nature, decreasing debt, John Cartwright beyond capitalism and socialism in Africa, Richard L. Sklar.

Computed activation energies and rate constants for forward and reverse transfers of hydrogen atoms

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTComputed activation energies and rate constants for forward and reverse transfers of hydrogen atomsStanley Wallace Mayer and Leroy SchielerCite this: J. Phys. Chem. 1968, 72, 1, 236–240Publication Date (Print):January 1, 1968Publication History Published online1 May 2002Published inissue 1 January 1968https://doi.org/10.1021/j100847a044RIGHTS & PERMISSIONSArticle Views76Altmetric-Citations41LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (569 KB) Get e-Alerts

Simultaneous Transmission and Reception in Radio Telephony

After reviewing the methods of duplex radio communication previously proposed, the author describes a divided-branch antenna arrangement with supplementary balancing coil, for this purpose. The theory and mode of adjustment of the system are explained. The application of this method in practice to ship-to-shore radio telephony is described, and reference is made to the necessary wire-to-radio and reverse transfers. Guided radio telephony and telegraphy over high tension transmission lines is considered. The use of a single oscillation generator for a number of stations is shown to be possible. An actual transmission of this type is described in detail.