bluuebunny/crossref_metadata_2025 huggingface dataset:
Preparation and plasticizing characteristics of a series of symmetrical and unsymmetrical N,N‐Disubstituted oleamides
Authors: Magne Frank C. , Mod Robert R. , Skau Evald L.
Published: September 2008

Thirty‐five N,N‐disubstituted oleamides, mostly dialkyl oleamides, have been prepared and evaluated as plasticizers for vinyl chloride‐vinyl acetate copolymer to investigate the relative effect upon plasticizer performance of N,N‐symmetrical and unsymmetrical substitution; groups such as alkyl, cycloalkyl, benzyl, 2‐alkoxyethyl, 2‐acetoxyethyl, 2‐(3‐carbobutoxypropionlyoxy)ethyl, 2‐(3‐carbohexanoxypropionyloxy)ethyl, and cyanoethyl have been investigated in systematic combinations. The compatibility of symmetrical or unsymmetrical N,N‐dialkyl oleamides, involving normal, branched, or cyclic alkyls, is controlled by the total carbon count of the combined substituent groups rather than that of the larger group. For retention of compatibility the total carbon count must not exceed about 13 atoms. Symmetrical and unsymmetrical dialkyl oleamides of the same total alkyl carbon count do not differ significantly in their plasticizing characteristics. Acyclic N,N‐dialkyl oleamides are, with few exceptions, highly efficient plasticizers, which impart good, sebacate‐like, low‐temperature impact performance to the plastic composition. A substituent attached to the nitrogen through a secondary carbon severely impairs plasticizer efficiency and cyclic or cycloalkyl substituents are detrimental to low‐temperature performance. Substitution of an alkyl group for one of the N,N‐disymmetrical substituents has little or no effect upon low‐temperature impact performance. Many of the disubstituted oleamides impart antistatic properties to the plastic composition.
C18‐saturated cyclic acids from linseed oil: A structural study
Authors: Friedrich J. P.
Published: September 2008

The preparation of C18‐saturated cyclic acids from linseed oil by heat treatment in the presence of alkali, followed by hydrogenation and subsequent isolation of the cyclic fraction, gives rise to a series of at least 11 isomers as evidenced by GLC. Eight of these isomers have now been shown to be geometric pairs of positional isomers with the following general formula: {fx244–1} An unequivocal synthesis of isomers (x=0,1,2 and 3) indicates that the principal positional isomer (ca. 55%) of HCal is 9‐(2′‐n‐propylcyclohexyl)‐nonanoic acid. This isomer undoubtedly results from the cyclization of 10,12,14‐octadecatrienoic acid present in the isomerized mixture. The predominance of this isomer is further substantiated by mass spectral analysis. The four positional isomers prepared constitute about 80% of the mixture as determined by gas‐liquid chromatography. The four synthetic aromatic positional isomers show single peaks whereas their hydrogenated counterparts show two peaks. Thus each of the positional isomers of saturated cyclic acids is composed of two geometric isomers.
Quantitative determination of cyclopropenoid fatty acids in cottonseed meal
Authors: Levi R. S. , Reilich H. G. , O'Neill H. J. , Cucullu Alva F. , Skau E. L.
Published: September 2008

A rapid analytical procedure for determining the residual cyclopropenoid fatty acids (CPA) in cottonseed meal has been developed. The procedure involves room‐temperature extraction of crude CPA‐containing lipids with a hexane‐water‐acetone azeotrope solvent, followed by a benzenemethanol wash. The crude lipids are then converted to methyl esters by methanolysis with sodium methoxide. Extraction with petroleum ether, followed by washing with aqueous acetone, results in a substance which is free from interfering materials. The purified methyl esters are then analyzed for CPA by a spectrophotometric modification of the Halphen reaction.
Fatty acid composition and glyceride structure of piglet body fat from different sampling sites
Authors: Stinson C. Gail , deMan John M. , Bowland John P.
Published: September 2008

Pigs were slaughtered at 16 weeks of age, and fat samples were obtained from outer and inner shoulder, outer and inner loin, and kidney. Fatty acid composition and glyceride type of distribution were determined. Glyceride structure was determined by pancreatic lipase hydrolysis. There were highly significant differences in fatty acid composition between sites. Fatty acids containing less than 18 carbon atoms were preferentially incorporated in the internal positions of the glycerides. The content of saturated fatty acids and fatty acids containing less than 18 carbon atoms at the 2‐position of shoulder and loin glycerides was higher than in kidney glycerides. Differences in glyceride types were noted between sites.
Limiting temperature and relative humidity for growth and production of aflatoxin and free fatty acids byAspergillus flavus in sterile peanuts
Authors: Diener Urban L. , Davis Norman D.
Published: September 2008

Sound mature kernels, broken mature kernels, immature kernels, and unshelled Early Runner peanuts were heat‐treated in controlled environment cabinets and inoculated with spores ofAspergillus flavus. Treatments were incubated at 97‐99% relative humidity at different temperatures ranging from 5 to 55C and also at 30C with relative humidities ranging from 55 to 99%. Samples were removed after 7 and 21 days and assayed for aflatoxin, free fatty acids, and peanut kernel moisture. The limiting relative humidity for aflatoxin production byA. flavus was 85ŷ1% relative humidity for 21 days at 30C. The limiting low temperature for visible growth and aflatoxin production by the fungus was 13ŷ1C for 21 days at 97‐99% relative humidity. Damaged kernels, however, developed some afllatoxin in 21 days at 12C. The maximum temperature for aflatoxin production was 41.5ŷ1.5C for 21 days at 97‐99% relative humidity. Fungus growth and sporulation at 43C were equal to that at 40C, but no aflatoxin was produced. Moisture content of immature kernels was higher at equilibrium with the same relative humidity than the moisture content of sound mature kernels, damaged kernels, or kernels from unshelled peanuts. There appeared to be no proportional quantitative correlation between synthesis of aflatoxin and production of free fatty acids in nonliving peanuts, but no aflatoxin was produced without a simultaneous increase in free fatty acids.
Determination of gossypol in leaves and flower buds ofGossypium
Authors: Smith F. H.
Published: September 2008

A method is described for the determination of free gossypol in cotton leaves with greater accuracy. The improved accuracy results from the elimination of the interference from chlorophyll and from quickly converting the extracted gossypol to the dianilino derivative. Methods for the determination of the free and bound gossypol in cotton flower buds are described.
A method for assessing evergreen habitats using phytodiversity and geospatial techniques in tropical rain forests of Southern Western Ghats (India)
Authors: Giriraj A. , Murthy M. S. R. , Ramesh B. R. , Dutt C. B. S.
Published: September 2008

We have used data generated using remote sensing and geographical information systems to categorize habitats, and then determined the relationship between the habitat categorizations and species‐distribution patterns. A biologically rich hotspot—Kalakad‐Mundanthurai Tiger Reserve, located at Southern Western Ghats, India, was chosen for this study. In order to spatially delineate areas of high species richness/diversity and endemic habitat zones, we have identified evergreen habitats in conjunction with landscape metrics, species assemblage, micro‐habitats like slope, topography, species endemism, and proportion of core and edge species. A total of 236 species and 2,920 individuals were recorded using systematic stratified plots of 0.1 ha covering 47 plots. Hierarchical cluster analysis was done using Ward's method. Plot information was used to identify clusters based on species density. The analysis showed five species assemblages that are quite distinct from each other in terms of dominant species. The distribution of endemic and edge species, land cover heterogeneity, and continuity of patches in these clusters were evaluated to understand the degree of disturbance and intactness at landscape scale. Integration of species assemblages and topography brought out four major elevation‐slope complexes. Information on species composition (robust field survey) with spectral (hybrid classification) properties has shown 72% overall accuracy and distinguished four evergreen sub‐groups and other land cover classes. The developed approach assumes great importance in the assessment of biodiversity and prioritizing the areas of conservation.
Intermittent active motion versus immobilization in the treatment of Staphylococcus aureus-induced arthritis in a rabbit model
Authors: Hamel Antoine , Caillon Jocelyne , Jacqueline Cédric , Batard Eric , Boutoille David , Bugnon Denis , Miégeville Anne-Françoise , Rogez Jean-Michel , Potel Gilles
Published: September 2008

Purpose

This study has evaluated the effects of immobilization versus intermittent active motion on cartilage and on antibiotic efficacy in a rabbit septic arthritis model.

Methods

Rabbits were infected and assigned to one of four groups: group 1, no treatment without immobilization (allowing intermittent active motion); group 2, cast; group 3, oxacillin without immobilization; group 4, oxacillin and cast. Animals were sacrificed 21 days later. Bacterial counts and lateral radiograms were performed. A radiological score was calculated.

Results

Immobilization had no effect on oxacillin efficacy and a deleterious effect on the radiological score.

Conclusion

Intermittent active motion has allowed a better cartilage healing during the treatment of septic arthritis.
Bald'sLeechbookand thePhysica Plinii
Authors: Adams J. N. , Deegan Marilyn
Published: September 2008

The study of the sources of the Anglo-Saxon medical texts began more than a hundred years ago with T.O. Cockayne's monumental edition of most of the medical, magical and herbal material extant in Old English. Cockayne demonstrated that the most significant text in this corpus, the late ninth-century compilation known as Bald'sLeechbook, drew on an impressive range of Latin source materials. Recent work by C.H. Talbot and M.L. Cameron has further extended our knowledge of the classical texts which underlie theLeechbook. Among the significant sources is the text known as thePhysica Plinii. Although thePhysicasurvives in several recensions, there has as yet been no systematic study of the relationship between these recensions and the version of the Latin text used by the Old English compiler. The present article investigates Bald'sLeechbookas a witness to the history of thePhysica Plinii, and demonstrates the complexity of the transmission of the latter work.
The decoration of the Tanner Bede
Authors: Gameson Richard
Published: September 2008

Oxford, Bodleian Library, Tanner 10 is the oldest extant copy of the Old English translation of Bede,Historia ecclesiastica gentis Anglorum. The volume dates from the early tenth century. This in itself adds significantly to its interest, for manuscripts produced in England during the sixty or so years from s. ix2–x1are scarce. It is ornamented with a remarkable set of decorated initials which are of considerable importance for understanding the characteristics and development of manuscript art during this period, and this is our primary concern here. The text of Tanner 10 was edited at the end of the last century, its codicology and palaeography have recently been reviewed, and a complete facsimile edition is currently being prepared: an examination of its extensive decoration is long overdue. To put this art-work in its context, before turning to the manuscript itself, it will be helpful first to review briefly the main classes of decorated initials which appear in late Anglo-Saxon books as a whole, and then to examine the early history of the particular type that was used in the Tanner Bede.
THE PROGRESSIVE ORIGINS OF THE ADMINISTRATIVE STATE: WILSON,
GOODNOW, AND LANDIS
Authors: Pestritto Ronald J.
Published: September 2008

The American administrative state is a feature of the new liberalism
that is largely irreconcilable with the old, founding-era liberalism. At
its core, the administrative state, with its delegation of legislative
power to the bureaucracy, combination of functions within bureaucratic
agencies, and weakening of presidential control over administration
undercuts the separation-of-powers principle that is the base of the
founders' Constitution. The animating idea behind the features of the
administrative state is the separation of politics and administration,
which was championed by James Landis, the New-Deal architect of the
administrative state for President Franklin Roosevelt. The idea of
separating politics and administration, and the faith such a separation
requires in the objectivity of administrators, did not originate with
Landis or the New Deal but, instead, with the Progressives who had come a
generation earlier. Both Woodrow Wilson and Frank Goodnow were pioneers in
advocating the separation of politics and administration, and made it the
centerpiece of their broad arguments for constitutional reform.
PROGRESSIVISM AS A NATIONAL NARRATIVE IN BIBLICAL-HEGELIAN
TIME
Authors: Eisenach Eldon J.
Published: September 2008

Progressive intellectuals at the turn of the last century founded the
modern American university, created its disciplines and edited the
journals that codified their thoughts. They created the ligaments of the
national administrative and regulatory state; they helped legitimate the
creation of a national financial and industrial corporate economy. Through
the writings of Lyman Abbott, Albion Small, and Simon Patten, three
features of progressive thought are underlined: the primacy of a
narrative, their hostility to “principled” or
abstract-philosophical forms of political and social thought, and their
confidence that historical modes of social inquiry would produce
“laws”? of progress that would guide practice and anchor
values integrating self and society on a democratic basis. Five topics
contain these animating features: national patriotism, the new industrial
economy, a new democratic ethic, social Christianity, and their critique
of the dominance of constitutional jurisprudence and law in American
political institutions and practices.
PROCEDURAL VERSUS SUBSTANTIVE JUSTICE: RAWLS AND NOZICK
Authors: Schaefer David Lewis
Published: September 2008

This paper critically assesses the “procedural” accounts
of political justice set forth by John Rawls in A Theory of
Justice (1971) and Robert Nozick in Anarchy, State, and
Utopia (1974). I argue that the areas of agreement between Rawls and
Nozick are more significant than their disagreements. Even though Nozick
offers trenchant criticisms of Rawls's argument for economic
redistribution (the “difference principle”), Nozick's own
economic libertarianism is undermined by his “principle of
rectification,” which he offers as a possible ground in practice for
the application of something like the difference principle. Both
Rawls's and Nozick's accounts of justice fail because of their
abstraction from human nature as a ground of right. At the same
time the libertarianism on which they agree in the non-economic sphere
would deprive a free society of its necessary moral underpinning. Rawls
and Nozick err, finally, by demanding that the policies pursued by a just
society conform to theoretical formulas concocted by philosophy
professors, rather than leaving room (as Lockean liberalism does) for the
adjustment of policies to particular circumstances based on
statesmen's prudential judgment and the consent of the governed.
Particularly troubling from the perspective of a citizen seriously
concerned with the advancement of justice and freedom is both
thinkers' shrill denunciations of existing liberal societies for
failing to conform to their particular strictures.
LIBERALISM BEYOND BORDERS
Authors: Lomasky Loren E.
Published: September 2008

While citizens of developed countries enjoy lives of unmatched
affluence, over a billion people struggle to subsist on incomes of less
than $1/day. Can't we conclude that their poverty constitutes a
glaring injustice? The answer almost certainly is yes—but not
because some countries are rich, nor because of inadequate levels of
redistribution. Liberal political theory traditionally maintains that
persons are rights-holders, and the primary duty owed them is
noninterference. Corrupt and tyrannical governments flagrantly violate the
liberty rights of their captive populations. External governments
conspicuously fail to respect noninterference, however, when they erect
barriers to trade between foreign nationals and their own citizens,
subsidize domestic industries, prevent innocent movement across borders by
would-be workers, and when they tender assistance to abusive states (such
as foreign aid that lines the pockets of kleptocrats and enhances their
power). The theory advanced here is similar to that of Rawls in rejecting
an international difference principle, but unlike Rawls it advances an
account of international justice as continuous with domestic principles of
justice.
LIBERALISM AND THE CONSTITUTION
Authors: Barber Sotirios A.
Published: September 2008

If the U.S. Constitution is a liberal Constitution, liberal
governments can have a constitutional obligation to secure positive
benefits or welfare rights. The original constitutional text describes a
government instrumental to the Preamble's abstract ends or goods.
Constitutional rights can be reconciled to the text's instrumentalist
logic by viewing them as functional to better conceptions of abstract ends
among actors who would compensate for their fallibility. The
Federalist confirms the instrumentalism of the constitutional text.
Conservative writers who treat negative liberties as constitutional ends
err in several ways. They assume rational actors would establish a
government for the sake of limiting it, and they ignore the positive
nature of goods (life, liberty, property) that are the objects of negative
liberties. They also fail to see that tax-supported protections for all
positive goods, including the objects of negative liberties, must be
justified by public purposes.
FEDERALISM AND THE OLD AND NEW LIBERALISMS
Authors: Levy Jacob T.
Published: September 2008

The transition from a relatively federal to a relatively centralized
constitutional structure in the United States has often been identified
with the shift from classical to welfare liberalism as a matter of public
philosophy. This article argues against that distinction. The liberal
argument for federalism is a contingent one, built on approximations,
counterbalancing, and political power. A more federalist constitution is
not automatically a freer one on classical liberal understandings of
freedom. Neither is a more centralized constitution automatically a better
match with the ideals of welfare liberalism. The article sketches a
constitutional history of federalism from the founding, through an era in
which centralization was aligned with skepticism about liberal
constitutionalism (for both meanings of liberal), to an era in which
centralization was aligned with increases in liberal freedom (for both
meanings of liberal).
Timing in late babbling
Authors: Boysson-Bardies Bénédicte De , Bacri Nicole , Sagart Laurent , Poizat Michel
Published: September 2008

The temporal organization of the late babbling of a French child during the pivotal period between babbling and the production of meaningful utterances is studied. Two points are analysed: the segmental timing in terms of syllabic durations and the durations of sequences according to their intonational contours. Articulation rate in late babbling is fairly rapid and stable and does not vary with length of sequences. However, at the end of the period studied, longer durations are found for bi- and tri-syllabic sequences. This lengthening can be seen to reflect changes in the child's target programming and the constraints on co-articulation that it implies. Additional changes occur also as a function of intonational contours.
Content and context in early lexical development
Authors: Snyder Lynn S. , Bates Elizabeth , Bretherton Inge
Published: September 2008

Investigators have targeted the onset of reference in children at varying points on the developmental continuum. Their viewpoints seem to be related to issues of the contextual flexibility, content and composition of the lexicon in comprehension and production. This study considered all of the variables in the early vocabularies of 32 children with a mean age of 1; 1·7. An intensive maternal interview was used to obtain data on the words comprehended and produced by the children and the contexts which supported their interpretation and use. The findings pointed to a relative independence between the domains of comprehension and production. Vocabulary size was related to all contextually flexible items in production while only related to the contextually flexible predicates in comprehension. Further, there was evidence for an early version of the referential style that has been reported at later stages of development.
Wanted dead and alive: to what extent are hunting and protection of an endangered species compatible?
Authors: ROBINSON ELIZABETH J. Z.
Published: September 2008

Cash-constrained wildlife departments must increasingly look towards revenue-generating activities such as sales of permits for hunting common species combined with fines for those caught with rare species. Pertinent to west Africa, an optimal enforcement model demonstrates the conditions under which a department with neither external budget nor tourism revenue can fully protect a rare species, and the impact on other species and local hunters' livelihoods. The department's effectiveness is shown to depend critically on the extent to which hunters can discriminate among different species. Improvements in hunting technology selectivity are therefore a substitute for increased enforcement spending.
Poverty and spatial dimensions of non-timber forest extraction
Authors: LÓPEZ-FELDMAN ALEJANDRO , WILEN JAMES E.
Published: September 2008

Conservationists promote non-timber forest products (NTFP) to simultaneously alleviate poverty and conserve ecosystems. Unfortunately, little is known about how such products actually contribute to poverty alleviation, or how various complementary policies such as green marketing campaigns or cooperative management might impact resource health and users' welfare. This paper develops a simple NTFP extraction model that focuses on spatial and labor market dimensions of use in both managed and unmanaged settings. The model contrasts patterns of spatial use, resource health, and income generation under open access and community-managed institutions. We then test the conceptual model by investigating the case of xate production in the rainforest of Chiapas, Mexico, using survey work conducted over two separate periods. The empirical investigation reveals spatial patterns and labor market outcomes predicted by the model. We find NTFP use is mainly conducted by households with low opportunity costs of time and fewer income generation opportunities.
Exploiting common resources with capital-intensive technologies: the role of external forces
Authors: ENGEL STEFANIE , LÓPEZ RAMÓN
Published: September 2008

This paper focuses on the interactions between local communities having at least some degree of informal claims over natural resources and firms interested in commercially exploiting such resources, explicitly allowing for interventions by third parties interested in community welfare and environmental outcomes. Integrating conflict and bargaining theories, we develop a bargaining model with endogenous inside and outside options, in which the feasibility and outcomes of a potential bargaining game depend on the unraveling of a conflict stage and vice versa. The model implies that, contrary to the conventional bargaining model, distribution and efficiency cease to be separable. We show that certain third-party interventions in the bargaining process may have unexpected and counterproductive effects.
Experimental determination of the elasticity of iron at high pressure
Authors: Mao Wendy L. , Struzhkin Viktor V. , Baron Alfred Q. R. , Tsutsui Satoshi , Tommaseo Caterina E. , Wenk Hans‐Rudolf , Hu Michael Y. , Chow Paul , Sturhahn Wolfgang , Shu Jinfu , Hemley Russell J. , Heinz Dion L. , Mao Ho‐Kwang
Published: September 2008

We present a multitechnique approach to experimentally determine the elastic anisotropy of polycrystalline hcp Fe at high pressure. Directional phonon measurements from inelastic X‐ray scattering on a sample with lattice preferred orientation at 52 GPa in a diamond anvil cell were coupled with X‐ray diffraction data to determine the elastic tensor. Comparison of the results from this new method with the elasticity determined by lattice strain analysis of radial X‐ray diffraction measurements showed significant differences, highlighting the importance of strength anisotropy in hcp Fe. At 52 GPa, we found that a method which combines results from inelastic scattering and pressure‐volume measurements gives a shape in the velocity anisotropy close to sigmoidal (with a faster c and slower a axis) a smaller magnitude in the anisotropy and compared to velocities based on the lattice strain method which gives a bell shape velocity distribution with the fast direction between the c and a axes. We used additional results from nuclear resonant inelastic X‐ray scattering to constrain errors and provide additional validation of the accuracy of our results.
Magmatic and tectonic extension at mid‐ocean ridges: 2. Origin of axial morphology
Authors: Ito Garrett , Behn Mark D.
Published: September 2008

We investigate the origin of mid‐ocean ridge morphology with numerical models that successfully predict axial topographic highs, axial valleys, and the transition between the two. The models are time‐dependent, simulating alternating tectonic and magmatic periods where far‐field extension is accommodated by faulting and by magmatism, respectively. During tectonic phases, models predict faults to grow on either side of the ridge axis and axial height to decrease. During magmatic phases, models simulate magmatic extension by allowing the axial lithosphere to open freely in response to extension. Results show that fault size and spacing decreases with increasing time fraction spent in the magmatic phase FM. Magmatic phases also simulate the growth of topography in response to local buoyancy forces. The fundamental variable that controls the transition between axial highs and valleys is the “rise‐sink ratio,” (FM/FT)(τT/τM), where FM/FT is the ratio of the time spent in the magmatic and tectonic periods and τT/τM is the ratio of the characteristic rates for growing topography during magmatic phases (1/τM) and for reducing topography during tectonic phases (1/τT). Models predict the tallest axial highs when (FM/FT)(τT/τM) ≫ 1, faulted topography without a high or valley when (FM/FT)(τT/τM) ∼ 1, and the deepest median valleys when (FM/FT)(τM/τT) < 1. New scaling laws explain a global negative correlation between axial topography and lithosphere thickness as measured by the depths of axial magma lenses and microearthquakes. Exceptions to this trend reveal the importance of other behaviors such as a predicted inverse relation between axial topography and spreading rate as evident along the Lau Spreading Center. Still other factors related to the frequency and spatial pervasiveness of magmatic intrusions and eruptions, as evident at the Mid‐Atlantic and Juan de Fuca ridges, influence the rise‐sink‐ratio (FM/FT)(τT/τM) and thus axial morphology.
Low‐frequency interaction between horizontal and overturning gyres in the ocean
Authors: Spall M. A.
Published: September 2008

Low‐frequency variability of the horizontal circulation in an idealized, eddy‐permitting, numerical model drives the dominant mode of low‐frequency variability in the meridional overturning circulation. This coupling takes place through the influence of lateral advection in the cyclonic high‐latitude boundary current on the mixed layer depth along the boundary. The mean and low‐frequency variability of the meridional overturning circulation are well predicted by a diagnostic estimate that assumes the downwelling is controlled by the thermal wind shear within the mixed layer along the boundary, which is in turn determined by a simple balance between lateral advection and surface cooling. The more general result is the demonstration that the mean and low frequency variability of the meridional overturning streamfunction are controlled by the baroclinic pressure gradient within the mixed layer along the boundary, which may be influenced by numerous factors such as low‐frequency variability in lateral advection, wind stress, surface buoyancy fluxes, or ice melt and freshwater runoff.
HF radar observations of high‐velocity E region echoes from the eastward auroral electrojet
Authors: Makarevich Roman A.
Published: September 2008

We present a statistical analysis of short‐range E region echoes observed by the Super Dual Auroral Radar Network (SuperDARN) HF radars in the evening sector (16–22 MLT) over 3 years. Significant populations of the high‐velocity (350–450 m/s) E region echoes similar to the classical Type 1 echoes are observed by 4 zonally‐looking SuperDARN radars at small magnetic L‐shell angles. The spatial occurrence pattern of Type 1 echoes is investigated. It is shown that the latitudinal (slant range) extent of the region where Type 1 echoes occur increases as the L‐shell angle decreases, which is interpreted as widening of the aspect angle instability cone with the flow angle decrease. The echoes with unusually high velocities (500–600 m/s) observed by the Syowa East HF radar are also investigated. These echoes are seen at all L‐shell angles (15°–75°) and their Doppler velocity increases with range and exhibits little variation with L‐shell angle. The echoes occur at ranges 360–495 km when the strong low‐velocity echoes (P > 30 dB, V < 200 m/s) are observed at ranges 225–360 km. We analyze the echo occurrence and velocity dependencies on the simultaneously observed F region echo velocity (plasma drift velocity) and E region echo power. It is suggested that the auroral E region echoes with unusually high velocities observed at large flow angles are similar to the vertically propagating Type 1 echoes reported previously in observations at the magnetic equator and are likely to be secondary waves generated through nonlinear mode coupling processes.
Model‐predicted distribution of wind‐induced internal wave energy in the world's oceans
Authors: Furuichi Naoki , Hibiya Toshiyuki , Niwa Yoshihiro
Published: September 2008

The distribution of wind‐induced internal wave energy in the world's oceans is investigated using a full three‐dimensional primitive equation model. Special attention is directed to the global energy input to the surface near‐inertial motions and the subsequent downward energy propagation into the deep ocean. We find that the model results for near‐inertial energy in the oceanic mixed layer, depth‐integrated horizontal energy fluxes, and vertical structures of WKB‐scaled kinetic energy are all consistent with the available observations in the regions of significant wind energy input and that the annual mean of the global wind energy input becomes ∼0.4 TW. It is also found that most of the wind‐induced energy resides in high vertical modes, 75–85% of which is dissipated in the surface 150 m. The present study therefore predicts that the total wind‐induced near‐inertial energy available for deep‐ocean mixing is limited to, at most, 0.1 TW, which is an order of magnitude smaller than previously estimated. Adding the energy flux from tide‐topography interactions of ∼0.9 TW, we can conclude that the total energy available for deep‐ocean mixing is ∼1.0 TW, obviously falling short of the required power to sustain the global overturning circulation. This might suggest the existence of other important energy sources, such as the one through geostrophic adjustment processes, and/or additional mechanisms sustaining the global overturning circulation, such as effects of Ekman upwelling in the Southern Ocean. Another possibility is that previous estimates of the volume transport of the global overturning circulation might be too large.
A method for continuous estimation of clear‐sky downwelling longwave radiative flux developed using ARM surface measurements
Authors: Long C. N. , Turner D. D.
Published: September 2008

We present an improved self‐adaptive methodology for the continuous estimation of downwelling clear‐sky longwave (LW) radiative flux based on analysis of surface irradiance, air temperature, and humidity measurements that includes a term to account for near surface optically thin haze. Comparison between our estimations and clear‐sky LW measurements for many years of data from the Atmospheric Radiation Measurement (ARM) Climate Research Facility’s Southern Great Plains (SGP), Tropical Western Pacific (TWP), and North Slope of Alaska (NSA) sites show agreement at about the 4 W m−2 level, with 75%, 94%, and 68% of the data falling within that range for the SGP, TWP, and NSA sites, respectively. Although there is no exact means of determining the uncertainty associated with the clear‐sky LW estimations, our analyses and comparison with detailed radiative transfer (RT) model calculations suggest our estimations on average are no worse than model calculations that require temporally and spatially averaged input information. Our technique exhibits a high degree of repeatability for the downwelling LW cloud effect, with agreement at about the 3 W m−2 level. Applying our technique and that of Long and Ackerman (2000) to 15 years of data from the ARM SGP site shows the maximum all‐sky and clear‐sky SW and LW occurs during summer, with the greatest year‐to‐year clear‐sky SW variability occurring in fall. The downwelling LW cloud effect is fairly constant across the seasons, but the greatest SW cloud effect occurs in spring. The downwelling net cloud effect is dominated by the SW, with the largest effect occurring in spring (−64 W m−2) and the smallest occurring during winter (−21 W m−2).
Sensitivity of catchment‐aggregated estimates of soil carbon dioxide efflux to topography under different climatic conditions
Authors: Webster K. L. , Creed I. F. , Beall F. D. , Bourbonnière R. A.
Published: September 2008

Soil respiration (Rs) is an important component of regional carbon budgets in forested landscapes. Within a sugar maple forest on the Algoma Highlands of the Canadian Shield, mosaics of topographic features create gradients in environmental conditions and carbon pools that influence the pattern of Rs within the region. The sensitivity of catchment‐aggregated Rs (CAR) to different spatial partitioning schemes of the landscape under different climate scenarios was examined in two contrasting catchments: one dominated by uplands (C35); the other containing uplands, critical transition zones (transiently saturated areas in isolated depressions or adjacent to wetlands, streams and lakes) and wetlands. CAR was estimated using a six topographic feature representation of the catchments including crest, backslope, footslope, toeslope, inner and outer wetland. CAR was underestimated (−7.4%) or overestimated (30.8%) if coarser spatial partitions were used, but the amount of error differed between catchments and with climatic conditions. A single feature (upland) partitioning scheme performed poorly under all climatic conditions (warm‐wet, warm‐dry, cool‐wet and cool‐dry). A two feature (upland and wetland) partitioning scheme showed improvement, but a partitioning scheme with a minimum of three features (upland, transition and wetland) was needed for accurate estimates of CAR in topographically varying catchments. The critical transition zone had the highest rates of Rs under all climate scenarios, and the critical transition zone and wetland became increasingly larger contributors to CAR under warmer and drier conditions. These observations point to the importance of accounting for the differential contribution of topographic features to Rs in carbon budget models. Failure to do so may lead to inaccurate estimates of landscape‐scale Rs.
Simulation of modern and middle Cretaceous marine δ18O with an ocean‐atmosphere general circulation model
Authors: Zhou J. , Poulsen C. J. , Pollard D. , White T. S.
Published: September 2008

We have developed a coupled ocean‐atmosphere general circulation model, the GENESIS‐MOM model, with the ability to transport and fractionate water isotopes in the ocean and atmosphere. The model is used to predict modern and Cretaceous precipitation and seawater δ18O. The model reproduces the large‐scale modern‐day isotopic distribution. In the zonal mean, the difference between simulated and observed seawater δ18O is within 0.2‰ in the low and middle latitudes and within 1‰ at high latitudes. In comparison to modern, simulated Cretaceous surface seawater δ18O is systematically depleted by 0.3‰ at low and middle latitudes. These differences are attributed to equilibrium fractionation during surface evaporation at low latitudes and an increased partitioning of 18O from the surface into the deep ocean due to intermediate and deep water formation in subtropical basins in the Cretaceous. We also find that regional seawater δ18O is significantly influenced by the paleobathymetry and the resolution of oceanic gateways, boundary conditions that are not well known for the past. Our simulation of Cretaceous seawater δ18O has major implications for oxygen isotope paleothermometry. We conclude that conventional assumptions of past seawater δ18O may lead to an overestimate of Cretaceous sea‐surface temperatures, especially at middle and high latitudes.
Conductivity of a quasi-one-dimensional electron system over liquid helium in the presence of a nonuniform potential
Authors: Smorodin A. V. , Nikolaenko V. A. , Solokov S. S.
Published: September 2008

The conductivity of surface electrons in channels filled with liquid helium on the surface of a profiled substrate is investigated experimentally. It is found that the character of the dependence of the conductivity on the holding electric field normal to the helium surface depends strongly on the quality of the substrate. As the substrate quality deteriorates, anomalies (dips) appear on the field dependence of the conductivity at certain values of the holding potential. The position of the anomalies is independent of temperature and of the amplitude and frequency of the exciting potential. Models are proposed for qualitative explanation of the observed behavior. The temperature dependence of the conductivity at high charge densities on the substrate is also investigated.
Effect of a semiconductor coating on electron transport in amorphous and crystalline metal films
Authors: Kuz’menko V. M.
Published: September 2008

The effect of an amorphous Sb coating on the resistivity ρ of amorphous and crystalline V, Yb, and Bi films is investigated. The values of ρ decrease for both phase states of V and Bi and increase for Yb. The effect of a coating on ρ is limited by the thickness of the coating dcov0=10–16nm, depending on the type and phase state of the base metal. Increasing the coating thickness to dcov>dcov0 does not change ρ further. The observed changes in ρ are attributed to electron flow from amorphous antimony into Bi and V and from amorphous and crystalline Yb films into amorphous antimony with a contact potential difference forming between the metal and semiconductor layers. In the process the density of states of the conduction electrons in the metal changes, and this is responsible for the change in ρ.
Charge ordering, internal structural parameters, and magnetic susceptibility of Nd2∕3Ca1∕3MnO3: driving forces of a phase transition
Authors: Beznosov A. B. , Fertman E. L. , Desnenko V. A.
Published: September 2008

The temperature dependences of the long diagonals dMn–O of the MnO6 octahedron and the magnetic susceptibility χ of Nd2∕3Ca1∕3MnO3 in the temperature interval 100–290K are investigated. The functions dMn–O(T) and χ(T) are found to have anomalies in the charge-ordering range (Tco≈212K). The sharp decrease of the diagonal dMn–O2s agrees with phase-transition notions, according to which the spatial modulation of the charge density is due to the modulation of the Mn–Mn bond lengths. The most likely driving forces of the transition are the Peierls lattice instability and Jahn–Teller stability of the MnO6 octahedron at the Mn3+ ions. The hysteresis of the temperature dependence χ(T) in the paramagnetic region shows indirectly that structural phase separation occurs together with the transition. The parameters of the function χ(T) indicate that ferromagnetic clusters consisting of one, two, or three ion pairs Mn3+–Mn4+ form in the system in the temperature intervals 274K⩽T⩽290K, 224K⩽T⩽252K, and 130K⩽T⩽198K, respectively.
Collective spin-wave excitations in the t-J model
Authors: Mironova S. F. , Zubov É. E.
Published: September 2008

The influence of the kinematic interaction and indirect exchange of d electrons on the magnetic structure of a narrow-band Hubbard magnet is investigated using diagrammatic perturbation theory. All contributions to the combined population and the spin Green’s function are examined to the first order of perturbation theory. A self-consistent equation is found for the order parameter of the phases. All contributions to the mass operator are determined with effective “dressing” of the interaction lines taken into account. The effect of indirect anti-ferromagnetic exchange on the spin wave spectrum and the damping of elementary excitations are investigated for ferromagnetic and paramagnetic phases. The correction to the frequency of spin-wave excitations at zero temperature and for hole concentrations c⪡1, proportional to c4∕3, is calculated for a ferromagnetic structure. As indirect exchange increases in magnitude, the spin-wave excitation frequencies decrease linearly, in agreement with the results obtained by Nagaoka and Zaitsev. It is found that the spin-wave spectrum near the Fermi level is coherent. The transverse dynamic susceptibility of the system is calculated for uniform ferromagnetic and paramagnetic structures.
Features of the thermal expansion of dense nanoceramic CuO
Authors: Gizhevskii B. A. , Kozlov E. A. , Krynetskii I. B. , Fishman A. Ya.
Published: September 2008

The thermal expansion of samples of high-density nanoceramic CuO is investigated. The nanoceramic is obtained by the method of loading coarse-grained copper oxide by spherically convergent shock waves. Anomalous behavior of the thermal expansion coefficient α of the oxide is observed in the temperature region below 50K (α⩽0). The appearance of these anomalies is explained by the presence of orientationally degenerate tunneling centers and/or low-temperature phase separation.
The effect of proton ordering on the thermal conductivity of clathrate tetrahydrofuran hydrate
Authors: Krivchikov A. I. , Romantsova O. O. , Korolyuk O. A.
Published: September 2008

The effect of proton ordering in tetrahydrofuran hydrate is detected using a technique based on measurement of thermal conductivity. The thermal conductivity of tetrahydrofuran hydrate is measured by the steady-state potentiometric method in the interval 2–150K. Two regimes are selected to observe the effect: (i) slow cooling of the hydrate sample, and (ii) doping of the hydrate with a small quantity of KOH alkali to a concentration of 10−4. Proton ordering affects the temperature dependence of the thermal conductivity, changing its glass-like behavior to crystal-like below 150K. The phonon maximum that appears in the temperature dependence of the thermal conductivity at T=17K is attributed to the cooperative process of local proton ordering stimulated by orientational and ionic defects.
Low-temperature plastic strain of ultrafine-grain aluminum
Authors: Éstrin Yu. Z. , Isaev N. V. , Grigorova T. V. , Pustovalov V. V. , Fomenko V. S. , Shumilin S. É. , Braude I. S. , Malykhin S. V. , Reshetnyak M. V. , Janeček M.
Published: September 2008

The microstructure and mechanical properties of ultrafine-grain (UFG) commercial-grade Al obtained by equichannel angular pressing (ECAP) are study in the temperature range 4.2–295K. Transmission electron microscopy and x-ray diffraction methods are used to show that as the number of passes increases, the grain size decreases, the grain shape becomes increasingly equiaxial, and the dislocation density inside a grain and the character of the intergrain boundaries change. An increase of the coherent scattering region and a decrease of the level of microdeformations indicate that pressing decreases the total density of imperfections of the crystal structure inside grains. As temperature decreases, the yield stress, plasticity, and strain hardening rate of UFG and coarse-grain polycrystals increase substantially. The deformation of UFG polycrystals at 4.2K becomes unstable (abrupt). The temperature dependences of the yield stress σy(T) of UFG and coarse-grain polycrystals, where the form of these dependences is characteristic for thermally activated detachment of dislocations from short-range potential barriers, are studied. The differences observed in the dependences σy(T) for UFG polycrystals are explained by a change in the nature of such barriers and the mechanism by which glide dislocations overcome them. The dependences of the yield stress σy and the coefficient of strain hardening θ on the grain size d are obtained. It is determined that the Hall–Petch relation describes the function σy(d) in the temperature interval 4.2–295K. The Hall–Petch coefficient increases as temperature decreases. The function θ(d) is monotonically decreasing at 295 and 77K but θ is independent of d at 4.2K. The experimental data are discussed within the framework of existing notions about the influence of the microstructure produced by ECAP on the evolution of the dislocation density during subsequent deformation.
Strain hardening of aluminum in the normal and superconducting states
Authors: Shumilin S. É.
Published: September 2008

The effect of predeformation of polycrystalline aluminum at 0.5K in the normal (N) and superconducting (S) states on the deforming stress at 77 and 293K is studied. It is found that the yield stress at 77 and 293K after predeformation is higher in the S state. This effect is attributed to a higher density of defects, which are formed during deformation, in the S state than in the N state.
Radial thermal expansion of single-walled carbon nanotube bundles at low temperatures
Authors: Dolbin A. V. , Esel’son V. B. , Gavrilko V. G. , Manzhelii V. G. , Vinnikov N. A. , Popov S. N. , Sundqvist B.
Published: September 2008

For the first time, the linear coefficient of radial thermal expansion is measured on a system of carbon single-walled nanotube (SWNT) bundles at low temperatures (2.2–120K). The measurements are performed using a dilatometer with a sensitivity of 2×10−9cm. A cylindrical sample 7mm high and 10mm in diameter was obtained by compressing powder. The resulting bundles of nanotubes are oriented perpendicular to the sample axis. The starting powder consisted of over 90% SWNTs with outer diameter 1.1nm, the length varying in the range 5–30μm. A change of sign of the radial thermal expansion coefficient at 5.5K is observed.