bluuebunny/crossref_metadata_2025 huggingface dataset:
Dependence of oligomer–oligomer incompatibility on chain length and pressure. I. Oligo‐isobutene/oligo‐propylene glycol and oligo‐styrene/oligo‐ethylene glycol
Authors: Wolf B. A. , Blaum G.
Published: June 2010

In the systems oligo‐isobutene/oligo‐propylene glycol and oligo‐styrene/oligo‐ethylene glycol, which invariably exhibit low temperature demixing, the corresponding upper critical solution temperatures increase with the chain length of the nonpolar component, whereas they run through a minimum when that of the particular glycol is raised. In all cases the incompatibility is enhanced by pressure, i.e., the mixing volumes result positive. Although these findings can be well understood qualitatively, a quantitative theoretical description of the chain length dependencies turns out to be impossible on the basis of current theories, probably because of the polar nature of the glycols. A very helpful evaluation and interpretation of these experimental results can however be performed by means of the lattice theory; it yields an enthalpy parameter and allows the extrapolation of the critical temperatures to higher molecular weights. For the pressure influences a qualitative forecast is possible in most cases by means of the Prigogine‐Patterson theory, if one parameter is adjusted to the measurements at normal pressure. Mixing volumes can also be estimated from the above‐mentioned enthalpy parameter and the slope of the experimental critical lines.
On the association phenomena of poly(methyl methacrylate) in nonpolar theta solvents
Authors: Suzuki Hidematsu , Hiyoshi Tatsuo , Inagaki Hiroshi
Published: June 2010

On a sample of poly(methyl methacrylate) prepared by an anionic polymerization technique with sodium biphenyl in tetrahydrofuran at –78°C, abnormal cloud‐point curves in nonpolar theta solvents, p‐xylene, and carbon tetrachloride were observed. The effect of solvent polarity on precipitation behavior of the sample solutions was examined. It is found that the more polar the solvent used, the more normal the cloud‐point curve becomes. Osmometry on the sample solutions in p‐xylene yielded much higher molecular weights than those obtained in a good solvent (toluene) and in a polar theta solvent (acetonitrile). The results obtained show that poly(methyl methacrylate) molecules prepared in this manner are liable to associate with each other in nonpolar media. This feature is considered to be responsible for the observed anomalies in the cloud‐point curves. This type of association is discussed and compared with the other two kinds of association phenomena reported in the literature.
Polymer solutions: A law of corresponding states for the coexistence curves
Authors: Daoud M.
Published: June 2010

We recall the main results of two different theories for temperature (T) and monomer concentration (C) dependence of flexible polymer solutions, namely, the Edwards–Flory–Huggins theory and the critical theory where an analogy with critical phenomena is used. These results are then compared to experimental data obtained by small‐angle neutron scattering associated to chain labeling by deuteration. Our new results are summarized in a (T, C) diagram and by a set of characteristic power laws. We also propose a law of corresponding states for the coexistence curves.
One long chain among shorter chains
Authors: de Gennes P. G.
Published: June 2010

We discuss the end to end distance RN of one long chain, with N monomers, immersed in a solution of shorter chains, each with P monomers, in a good solvent. When P increases, RN crosses over an excluded volume behavior (RN ∼ N3/5) to an ideal behavior (RN → R1n ∼ N1/2). The relevant crossover parameter Z is constructed here from an improved version of the Edwards screening idea, incorporating the correct scaling laws. The result is

where ϕp is the volume fraction of the P chains in the solution. The N chain will be ideal when Z ⪖ > 1, and swollen (non‐Gaussian) when Z ⪖ > 1.
Configurational behavior of adsorbed polymer molecules
Authors: Lal M. , Stepto R. F. T.
Published: June 2010

Monte Carlo calculations of the configurational behavior of adsorbed polymer molecules are described. Freely rotating lattice chains of 30, 50, 75, and 100 bonds adsorbing from athermal solutions at different adsorption energies have been studied. The adsorption energy is defined as Δϵs, the energy change on breaking a segment–solvent bond and forming a segment–surface bond. Adsorption occurs only for negative values of Δϵs. Results of calculations at Δϵs = −0.9kT and −0.5kT have been analyzed numerically and compared with previous data.

Several ways of characterizing the configurational behavior are presented in terms of fraction of segments adsorbed, thickness of adsorbed layer, “train,” “loop,” and “tail,” lengths, and (r2) and (s2) of the adsorbed chain. At Δϵs = −0.9kT the chains are strongly adsorbed with extended configurations and short tails. At Δϵs = −0.5kT the chains are only just adsorbing with the thickness of the adsorbed layer dominated by the lengths of the tails.

Finally, a visuographic technique for presenting the ciné display of the configurational behavior of the adsorbate chains is described briefly.
Structure and morphology of liquid‐crystalline polymers
Authors: Wendorff J. H. , Finkelmann H. , Ringsdorf H.
Published: June 2010

Liquid‐crystalline phases are characterized by structures intermediate between a three‐dimensionally ordered crystal and a disordered fluid. Polymers with liquid‐crystalline structures can be obtained from specific monomers containing mesogenic groups with a tendency to form liquid‐crystalline phases. These mesogenic groups are either incorporated into the main chain or attached to a chain as side groups. In both cases liquid‐crystalline structures, and also enantiotropic liquid‐crystalline phases, have been reported. Smectic polymers are characterized by layered structures with long‐range order in the direction of the layer normal and two‐dimensional short‐range order within the layers. The nematic polymers are characterized by a preferred direction on a microscopic scale and short‐range positional order of the centers of mass of the mesogenic groups. Thermal and textural properties are similar to the corresponding properties of low molecular weight liquid crystals.
Preparation and characterization of head‐to‐head polymers. VIII. Head‐to‐head poly(vinyl cyclohexane)
Authors: Helbig M. , Inoue H. , Vogl O.
Published: June 2010

Head‐to‐head poly(vinyl cyclohexane) (H‐H PVCH) was prepared from 2,3‐diphenylbutadiene, which was polymerized by radical, 1,4 polymerization to poly(2,3‐diphenylbutadiene) and then catalytically hydrogenated to H‐H PVCH, H‐H PVCH was also prepared by catalytic hydrogenation of H‐H polystyrene (PS). The catalytic hydrogenations were carried out at an initial hydrogen pressure of 2000 psi and a temperature of 200°C. Some chemical, physical, and thermal properties of H‐H PVCH were investigated and compared with the properties of atactic and isotactic head‐to‐tail (H‐T) PVCH. The glass transition temperature of the H‐H polymer was found to be 50°C lower than that of the atactic H‐T polymer which indicates that the backbone chain has more flexibility. Both H‐H and H‐T PVCH showed comparable thermal stability. The temperature of the maximum rate of thermal degradation by differential thermogravimetric analysis was approximately 40°C higher than that of the corresponding polystyrenes.
Isomeric copolymers of acetylenes
Authors: Simionescu C. , Dumitrescu Sv. , Percec V.
Published: June 2010

The triple bond opening in the cis position during Ziegler polymerization of acetylenes does not result however in pure cis polymers. The heat of polymerization and the exothermal effect of catalyst destroying has been found to be responsible for the variable cis content due to cis‐trans thermal isomerization. The cis‐trans thermal isomerization is accompanied by cyclization and scission of the polymer chains. These side reactions lead to copolymer structures instead of homopolymer ones. These processes probably determine the low thermal stability of the polymers (even at room temperature), and at the same time allow the interpretation of the order‐disorder phenomenon found by Ehrlich in the case of high crystalline polyphenylacetylene at about 120°C.
Properties and reactivity of polysuccinimide
Authors: Vlasák J. , Rypáček F. , Drobník J. , Saudek V.
Published: June 2010

A simple method has been suggested for the fractionation of polysuccinimide (PSI); the intrinsic viscosities of fractions were measured and the parameters of the Mark‐Houwink equation were determined. The possibilities of reactions of PSI with primary amines such as histamine, tyramine, tryptamine, mono‐BOC‐ethylenediamine, glycine nitroanilide, and ethanolamine were checked; the reaction rate constants and the effect of some catalysts were determined.
Radical coordination polymerization
Authors: Kabanov V. A.
Published: June 2010

In this paper different examples of the effect of coordination‐unsaturated metal compounds on the radical homo‐ and copolymerization of vinyl monomers are considered and analyzed. In all known cases homopolymerization proceeds according to the usual addition chain radical scheme and involve an initiation step with the formation of a primary radical. Complexed radicals or monomers take part in the chain propagation steps. In the case of copolymerization, a complexing agent can considerably influence apparent relative activities of monomers, decreasing or increasing the tendency to alternation. If two monomers are present in the system, one of which forms a complex with a Lewis acid, and the other is a donor with respect to this complex, the formation of a ternary donor‐acceptor complex also occurs in a number of cases. A ternary complex can fulfill the monomer function in the chain propagation reaction, i.e., it can add to the propagating chain as an independent kinetic species. In such cases, strictly alternating copolymers may be obtained. All mechanisms considered agree with the addition‐polymerization scheme. From the kinetic point of view the ternary complex addition is somewhat similar to an elementary step of Butler's inter‐intramolecular cyclopolymerization.
DSC studies on the activated anionic polymerization of ϵ‐caprolactam in the presence of crown compounds
Authors: Karger‐Kocsis József , Kiss László
Published: June 2010

Activated anionic polymerization of ϵ‐caprolactam was investigated in the presence and absence of crown compounds by a suitable differential scanning calorimetry (DSC) technique. It was demonstrated that crown compounds influenced the heterogeneous character of polymerizationresulting PA 6 of higher crystalline proportion and higher average molecular weight.
Structure–property relationships in main chain liquid crystal polyesters with flexible spacers
Authors: Lenz Robert W.
Published: June 2010

Investigations have been carried out in this laboratory over the past four years on the structure—property relationship in main chain, thermotropic liquid crystal polymers containing a variety of different types of mesogenic groups and flexible spacers. Our goal has been to relate the effect of polymer structure to the type of mesophase formed in the melt and to the melting and clearing temperatures of the mesophases. Many interesting, unusual, and unexpected results have been obtained in our survey, and this review is concerned with our observations on the molecular factors which determine the types of mesophases formed, nematic or smectic, and their transition temperatures and behaviors.
The polymerization of xylylene bisdialkyl sulfonium salts
Authors: Wessling R. A.
Published: June 2010

Paraxylylene bisdialkyl sulfonium salts can be polymerized in several different ways, yielding addition polymers as well as condensation polymers. The chemistry leads to a variety of polymers including poly(p‐xylylene), poly(p‐xylylidene), poly(xylylene sulfide)s, poly(xylylene oxide)s, and various α‐substituted polyxylylenes such as poly(p‐xylylene‐α‐dialkylsulfonium chloride). Addition polymers form via xylylene diradical intermediates. Condensation polymerization can be effected either by coupling with aldehydes or by nucleophilic displacement reactions.
Multicomponent gas sorption in glassy polymers
Authors: Koros W. J. , Sanders E. S.
Published: June 2010

Glassy polymers are nonequilibrium solids whose properties may change slowly due to time‐dependent variation in the excess volume and enthalpy functions of these materials. Measurable changes in the gas sorption behavior of samples exposed to different time–temperature histories below the polymer's glass transition temperature can be explained primarily in terms of differences between the excess volume of different samples. A simple physical and mathematical model will be described which relates excess sorption in glasses, compared to rubbery polymers, to sorption into excess volume frozen into the quenched matrix. The model will be explained for pure component gases and then generalized to treat multicomponent sorption data for the CO2/C2H4 and CO2/N2O systems in poly(methyl methacrylate). The rather complex mixed gas behavior can be predicted quantitatively using only pure component sorption data in conjunction with the generalized model for multicomponent gases. The model, based on the concept of competition of sorbing penetrants for the excess volume present in the glass, is successful for the two systems described above for total pressures up to 300 psia.
Homogeneous nucleation temperatures for concentrated polystyrene/benzene solutions
Authors: Prud'Homme Robert K. , Gregory Walter J. , Andres Ronald P.
Published: June 2010

Homogeneous nucleation temperatures for polystyrene/benzene solutions up to 60 wt% polymer have been measured. For polymer molecular weights from 17,500 to 100,000, homogeneous nucleation temperatures increase with increasing concentration from 226°C for pure benzene to 260°C for 60 wt% polymer. The experimental results have been compared to the predictions of homogeneous nucleation theory. It is concluded that for these solutions polymers affect the nucleation process principally through their effect on surface tension and solvent vapor pressure. For polystyrene solutions of molecular weight 600,000 or greater, a significant reduction in nucleation temperature was found. This phenomena appears to be caused by phase‐separated domains in these high molecular weight solutions.
Cvclization of polystyrene chains in the crossover region between theta and good solvents: Cyclization dynamics of polymers 12
Authors: Winnik Mitchell A. , Li Xiao‐Bai , Guillet J. E.
Published: June 2010

The rate constants and the equilibrium constants for end‐to‐end cyclization have been determined in seven solvents for a polystyrene chain of Mn ‐ 2900 and narrow molecular weight distribution. These values were obtained by measuring the kinetics of intramolecular excimer formation between pyrene groups attached to the chain ends. Values were plotted versus the Hildebrand solubility parameter h: It was found that not only did the rate of cyclization decrease in good solvents, but that the rate of ring opening was substantially faster in good solvents than in poor solvents. Consequently, the cyclization equilibrium constant is far more sensitive to the quality of the solvent than is the mean‐squared radius of gyration. The results are interpreted in terms of excluding volume effects on the end‐to‐end distance distribution function of the polymer.
Direct Evidence of Covalent Immobilisation of Microperoxidase‐11 on Plasma Polymer Surfaces
Authors: Yin Yongbai , Bilek Marcela M. M. , McKenzie David R.
Published: June 2010

The question of whether immobilised proteins are bound covalently on plasma activated or deposited polymers has been a challenge for almost 30 years, as there has been no directly evidence to conclude unambiguously. In this paper, we report evidence that a chemical binding reaction occurred during immobilisation of microperoxidase‐11 (MP‐11) proteins on plasma polymer surfaces. Untreated polymer surfaces were not resistant to detergent cleaning and did not show any increase of S 2p component after protein immobilisation, whilst all plasma‐deposited surfaces showed large amounts of immobilised MP‐11 proteins after detergent cleaning. We conclude that the MP‐11 protein had a chemical binding reaction thorough its cysteine residues with the plasma polymer surfaces.

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Tragverhalten und EN 1993‐1‐konforme Nachweisformate für Rahmenecken mit geschraubter Zuglasche
Authors: Rubert Achim , Schäfer Steffen
Published: June 2010

Für im Sinne der EN 1993‐1‐8 als biegesteif/starr zu bewertende Rahmenecken mit geschraubter Zuglasche wird mittels eines einfachen Stabwerkmodells unter Berücksichtigung der Grenztragfähigkeiten der Komponenten (plastische Berechnung) das Tragverhalten des Riegels im Bereich der Laschenverschraubung analysiert. Daraus werden zum Handnachweis geeignete Formeln zur Berechnung der Beanspruchungen und geeignete Nachweisformate der Tragfähigkeit nach EN 1993‐1‐1 und 1993‐1‐8 einschließlich eines Abschätzungsnachweises mit Extremwerten vorgestellt. Mögliche Sonderregelungen der nationalen Anhänge von EN 1993‐1‐1 und 1993‐1‐8 bleiben hier ohne Berücksichtigung. Unter Beachtung des statischen Satzes der Traglasttheorie werden damit sichere und gleichzeitig wirtschaftliche untere Grenzen der Tragfähigkeit der riegelseitigen Rahmenecke mit geschraubter Zuglasche dargestellt.

Am Beispiel einer ausgeführten Hallenkonstruktion zeigt sich, dass für den Bereich der Zuglaschenverschraubung mit diesen Nachweiskonzepten eine häufig geforderte und kostenerhöhende Zugflanschverstärkung unnötig ist.

Structural performance and EN 1993‐1 compliant design formats for frame corners with a bolted tension splice. For frame knees considered as fixed/stiff according to EN 1993‐1‐8, the structural performance of the rafter bolted to a tension slice is analyzed by means of a simple frame model with respect to maximum loadcarrying capacities of components (plastic calculation). Refering to this, formulas of calculations to determine the internal forces and the proofs of carrying capacity of the components due to EN 1993‐1‐1 and 1993‐1‐8 including a proof with extreme values are shown. Possible special regulations of national appendices of EN 1993‐1‐1 and 1993‐1‐8 remain here without consideration. With regard to the guarantied lower limit of the plastic collapse load several safe and economic calculation formats for the bolted side of a frame knee are shown.

The example of a built hall construction shows that – following the proposed design formats – frequently demanded/arranged and additionally costs raising tension flange reinforcements are unnecessary.
Berechnung des Abhebens von verankerten Flüssigkeitsbehältern unter Erdbebeneinwirkung
Authors: Habenberger Jörg
Published: June 2010

Die horizontalen Einwirkungen aus Erdbeben können bei Flüssigkeitsbehältern zum Abheben des Bodenblechs führen. Damit verbunden sind zusätzliche Axialkräfte in der gegenüberliegenden Behälterwand und Verformungen des Bodenblechs. Insbesondere die Verdrehungen des Bodenblechs sind oftmals kritisch für den Nachweis der Erdbebensicherheit. Verankerungen können das Abheben wirkungsvoll begrenzen, wobei z. B. Ringfundamente oder Mikropfähle die in den Ankerbolzen auftretenden Zugkräfte aufnehmen. Im vorliegenden Beitrag wird die Wirkung der Verankerung am Gesamtsystem von Behälterwand und Bodenblech untersucht. Dieses wird mit ebenen FE‐Schalenelementen unter Berücksichtigung nichtlinearen Materialverhaltens für die Ankerbolzen modelliert. Der dynamische Druck des verankerten Behälters aus horizontaler Erdbebenanregung wird inkrementell als statische Last aufgebracht und mit dem statischen und dynamischen Flüssigkeitsdruck aus vertikaler Erdbebenanregung überlagert. In jedem Lastschritt wird iterativ das Abheben des Tankbodens berechnet. Die Ergebnisse werden den Angaben des EC 8, Teil 4, Anhang A gegenübergestellt.

Uplift analyses of anchored liquid storage tanks under earthquake excitation. Horizontal earthquake excitations may lead to an uplift of the base plate of liquid storage tanks. The uplift results in additional axial forces on the opposite site of the tank wall and rotational deformations in the base plate. Especially the rotation of the tank base plate is critical for the verification of the earthquake resistance. Anchorages can effectively restrict the uplift while ring foundation or piles bear the appearing tensile forces. In the present paper the effect of anchorages is analysed on the overall system of tank wall and base plate. The tank shell is modelled by flat shell elements. The anchor bolts are considered as spring elements with nonlinear material behaviour. The dynamic pressure of the anchored tank due to horizontal excitation is applied incrementally to the tank shell. The uplift and the material nonlinearity are considered by iterative calculations at every load step. The results are compared with the specifications of EC 8, part 4, appendix A.
The Importance of Process in Building an Executive Leadership Team: A Case Study
Authors: Zakariasen Kenneth L.
Published: June 2010

In today's competitive, fast-changing world of healthcare, organizations cannot tolerate ineffective leadership over the long term if they are to remain successful. It is very common for leadership teams to come together and immediately begin to do business…at least to attempt to do what each team member believes the group's business should be. Unfortunately, each person probably has a different idea of what the team's business should be, and how they should go about conducting it. This is a certain recipe for ineffectiveness.

The following case study examines how the executive team in a health sciences college approached the development of an effective leadership team, and discusses the importance of process to achieving the desired outcomes. The process so described can be used with any leadership team, but it should always be customized to suit the unique needs and desires of each team.
Health Policy and the Delivery of Evidence-Based Wound Care Using Regional Wound Teams
Authors: Campbell Karen , Teague Laura , Hurd Theresa , King John
Published: June 2010

As clinicians practicing wound management in all three sectors of the healthcare system, the authors have articulated specific issues relating to wound management. There is a lack of awareness of the extent of the problem. Best practice guidelines have been developed, however, their adoption and transfer into practice have been inconsistent. Basic education in the field is minimal or absent across all disciplines. Institutions and agencies lack the infrastructure and financial resources to support optimal healthcare delivery in wound prevention and management. As a result, there are significant problems and inconsistencies in access to wound care across Ontario.

This paper reviews the issues and background as related to pressure ulcer, diabetic foot ulcer and venous leg ulcer. Finally, the authors make specific health policy recommendations regarding the implementation of regional wound care teams.
Regionalization Reigns — But is Care Being Delivered Accordingly?: An Evaluation of Perinatal Care Delivery in a Regionalized Child Health Network
Authors: Alidina Shehnaz , Ardal Sten , Lee Paul , Raskin Lynn , Shennan Andrew , Young Linda Marie
Published: June 2010

The Child Health Network for the Greater Toronto Area (CHN), a network of 20 hospitals and 9 community care access centres, assessed one component of its early progress in building a regionalized system of perinatal care. Focusing on the relationship between hospital level of care and gestational age, the study showed that most births occurred at appropriately designated facilities. However, a quarter of newborns of gestational age <32 weeks were delivered at a lower level of care than is considered optimal. CHN's ongoing research will offer opportunities to assess the impact of regional models on their foremost goal — quality clinical care.
Waiting Time Care Guarantees: Necessity or Nemesis?
Authors: Joshi N.P. , Noseworthy F.T. , Noseworthy T.W.
Published: June 2010

One of the priorities of governments in Canada is to reduce long waiting times for health services. This has raised the prospect of introducing waiting time care guarantees. Such guarantees affirm the healthcare system's social contract with the public and provide an entitlement to Canadians to receive timely care. There are clinical, legal and political implications, which must be considered and well managed before introduction. Other countries have ventured down this path. They teach us that waiting time care guarantees are good policy and make good sense. Correspondingly, they remind us not to make a promise we are not ready to keep.
Linear and nonlinear mechanisms of sound radiation by instability waves in subsonic jets
Authors: SUPONITSKY VICTORIA , SANDHAM NEIL D. , MORFEY CHRISTOPHER L.
Published: June 2010

Linear and nonlinear mechanisms of sound generation in subsonic jets are investigated by numerical simulations of the compressible Navier–Stokes equations. The main goal is to demonstrate that low-frequency waves resulting from nonlinear interaction between primary, highly amplified, instability waves can be efficient sound radiators in subsonic jets. The current approach allows linear, weakly nonlinear and highly nonlinear mechanisms to be distinguished. It is demonstrated that low-frequency waves resulting from nonlinear interaction are more efficient in radiating sound when compared to linear instability waves radiating directly at the same frequencies. The results show that low-frequency sound radiated predominantly in the downstream direction and characterized by a broadband spectral peak near St = 0.2 can be observed in the simulations and described in terms of the nonlinear interaction model. It is also shown that coherent low-frequency sound radiated at higher angles to the jet axis (θ = 60°–707°) is likely to come from the interaction between two helical modes with azimuthal wavenumbers n = ±1. High-frequency noise in both downstream and side-line directions seems to originate from the breakdown of the jet into smaller structures.
Incarceration, Interrogation, and Counterterror: Do (Liberal) Democratic Institutions Constrain Leviathan?
Authors: Moore Will H.
Published: June 2010

States represent a solution to an important set of economic, political, and social problems. Whether one turns to philosophers such as Hobbes or Locke or more recent work by rational institutionalists such as Douglass North, it is something of a received wisdom that powerful states play a central and vital role in fostering economic, political, and social cooperation. The other edge of that sword, of course, is that powerful states that claim a monopoly on the legitimate exercise of coercion are ideally situated to predate, using methods that include incarceration without trial and torture. The very power that makes states effective at engaging in cooperation can weaken other organizations that might deter the state from predation. While democratic theory is not necessarily focused on the question of how we might constrain a powerful state's predation, democracy is—and, more specifically, liberal democratic institutions are—widely held to be one of the most important tools at our disposal to deter predation (e.g., Staton and Reenock 2010). Democracy, of course, refers to rule by the people, and in this article, I focus on universal suffrage as the means by which those who wield state power produce rule by the people. I refer to liberal democratic institutions, by contrast, as those institutions that perform a distinct—and, one can argue, antidemocratic—function: their purpose is to distribute power among multiple state actors in an effort to address the second edge of the sword described above and limit the tyranny of majorities. This article shows how this distinction usefully assists our assessment of the Bush administration's incarceration and interrogation policies in its war on terror.
BREAKING THE SILENCE
Authors: Gueye Abdoulaye
Published: June 2010

Since the turn of the millennium, French society has become the theatre of a noticeable Black agency. Few previous events have ignited the media's interest in a Black French agenda more than the Collectif Égalité-led “March for the dignity of Black peoples” and the formation of the Conseil Représentatif des Associations Noires (CRAN). Through these newly-founded organizations, French activists of African descent have been challenging the hegemonic ideology of color-blindness, and heralding the claims, problems, and expectations of postcolonial African-descended people.

Informed by this ideology of so-called color-blindness, the academic literature in France has been slow to account for this new form of political expression. Moreover, as this article will argue, postcolonial African-descended people have not been recognized as political agents in the French literature. Few studies have attempted to correct this myopic view by analyzing the current political dynamic of postcolonial African-descended people. Due to the state-centered or institutionalist approach, these studies are more concerned with highlighting external and structural factors, such as racial discrimination, at the expense of endogenous determinants. They focus on what postcolonial African-descended people are denied in the French society instead of investigating the qualities these citizens actually possess that enable them to organize collectively. This article is intended to contribute to this new literature. It will pinpoint the different transformations that postcolonial African-descended people have undergone from the 1960s through the 1990s, examine the resources and skills under these actors' control, and gauge the contribution of these resources and skills to the emergence of a Black collective voice.
Aerosol optical depth measurements in eastern China and a new calibration method
Authors: Lee Kwon H. , Li Zhanqing , Cribb M. C. , Liu Jianjun , Wang Lei , Zheng Youfei , Xia Xiangao , Chen Hongbin , Li Bai
Published: June 2010

We present a new calibration method to derive aerosol optical depth (AOD) from the MultiFilter Rotating Shadowband Radiometer (MFRSR) under extremely hazy atmospheric conditions during the East Asian Study of Tropospheric Aerosols: an International Regional Experiment (EAST‐AIRE) and the Atmospheric Radiation Measurement (ARM) Mobile Facility (AMF) deployment in China. MFRSR measurements have been made at Xianghe since September 2004 and at Taihu and Shouxian since March and May 2008, respectively. Aerosol property retrievals from CIMEL Electonique, Paris, Sun and sky radiometers located at each site show that aerosol loading is substantial and highly variable during a given year (averaged daily AOD550 = 0.80 ± 0.14). The conventional application of the Langley method to calibrate the MFRSR is not possible at these sites because there is a dearth of stable atmospheric and low‐AOD conditions. To overcome this limitation of the traditional Langley plot method, highest irradiance values at a given air mass during a given period are used here. These highest values can represent the clear‐sky and minimum aerosol loading conditions. A scatterplot of the AOD estimated by this method with the CIMEL Sun and sky radiometer AOD shows very good agreement: correlation coefficients are on the order of 0.98–0.99, slopes range from 0.93 to 0.97, and offsets are less than 0.02 for the three sites. AOD and Ångström exponents were derived from application of the method to all MFRSR data acquired at the three sites. AOD values at 500 nm are τ500 = 0.99 ± 0.71 (α500–870 = 1.45 ± 0.59) at Xianghe, 0.87 ± 0.54 (1.14 ± 0.31) at Taihu, and 0.84 ± 0.43 (1.15 ± 0.28) at Shouxian. Anthropogenic aerosols appear to dominate in the study region with significant contributions from large dust particles and influence of hydroscopic growth.
Thermal‐mechanical behavior of oceanic transform faults: Implications for the spatial distribution of seismicity
Authors: Roland Emily , Behn Mark D. , Hirth Greg
Published: June 2010

To investigate the spatial distribution of earthquakes along oceanic transform faults, we utilize a 3‐D finite element model to calculate the mantle flow field and temperature structure associated with a ridge‐transform‐ridge system. The model incorporates a viscoplastic rheology to simulate brittle failure in the lithosphere and a non‐Newtonian temperature‐dependent viscous flow law in the underlying mantle. We consider the effects of three key thermal and rheological feedbacks: (1) frictional weakening due to mantle alteration, (2) shear heating, and (3) hydrothermal circulation in the shallow lithosphere. Of these effects, the thermal structure is most strongly influenced by hydrothermal cooling. We quantify the thermally controlled seismogenic area for a range of fault parameters, including slip rate and fault length, and find that the area between the 350°C and 600°C isotherms (analogous to the zone of seismic slip) is nearly identical to that predicted from a half‐space cooling model. However, in contrast to the half‐space cooling model, we find that the depth to the 600°C isotherm and the width of the seismogenic zone are nearly constant along the fault, consistent with seismic observations. The calculated temperature structure and zone of permeable fluid flow are also used to approximate the stability field of hydrous phases in the upper mantle. We find that for slow slipping faults, the potential zone of hydrous alteration extends greater than 10 km in depth, suggesting that transform faults serve as a significant pathway for water to enter the oceanic upper mantle.
Teleseismic inversion for rupture process of the 27 February 2010 Chile (Mw 8.8) earthquake
Authors: Lay T. , Ammon C. J. , Kanamori H. , Koper K. D. , Sufri O. , Hutko A. R.
Published: June 2010

The 27 February 2010 Chile (Mw 8.8) earthquake is the fifth largest earthquake to strike during the age of seismological instrumentation. The faulting geometry, slip distribution, seismic moment, and moment‐rate function are estimated from broadband teleseismic P, SH, and Rayleigh wave signals. We explore some of the trade‐offs in the rupture‐process estimation due to model parameterizations, limited teleseismic sampling of seismic phase velocities, and uncertainty in fault geometry. The average slip over the ∼81,500 km2 rupture area is about 5 m, with slip concentrations down‐dip, up‐dip and southwest, and up‐dip and north of the hypocenter. Relatively little slip occurred up‐dip/offshore of the hypocenter. The average rupture velocity is ∼2.0–2.5 km/s.
Intraoperative Blood Flow Analysis of Direct Revascularization Procedures in Patients with Moyamoya Disease
Authors: Lee Marco , Guzman Raphael , Bell-Stephens Teresa , Steinberg Gary K
Published: June 2010

Moyamoya disease is characterized by the progressive stenosis and often occlusion of the terminal internal carotid arteries, which leads to ischemic and hemorrhagic injuries. The etiology is unknown and surgical revascularization remains the mainstay treatment. We analyzed various hemodynamic factors in 292 patients with moyamoya disease, representing 496 revascularization procedures, including vessel dimension and intraoperative blood flow, using a perivascular ultrasonic flowprobe. Mean middle cerebral artery (MCA) flow rate was 4.4±0.26 mL/min. After superficial temporal artery (STA)–MCA bypass surgery, flows at the microanastomosis were increased fivefold to a mean of 22.2±0.8 mL/min. The MCA flows were significantly lower in the pediatric (16.2±1.3 mL/min) compared with the adult (23.9±1.0 mL/min; P<0.0001) population. Increased local flow rates were associated with clinical improvement. Permanent postoperative complications were low (<5%), but very high postanastomosis MCA flow was associated with postoperative stroke (31.2±6.8 mL/min; P=0.045), hemorrhage (32.1±10.2 mL/min; P=0.045), and transient neurologic deficits (28.6±5.6 mL/min; P=0.047) compared with controls. Other flow and vessel dimension data are presented to elucidate the hemodynamic changes related to the vasculopathy and subsequent to surgical intervention.
Dealing with drought: social implications of different smallholder survival strategies in semi-arid rangelands of Northern Patagonia, Argentina
Authors: Easdale Marcos H. , Rosso Heber
Published: June 2010

Drought is a constant part of rangeland dynamics in arid and semi-arid regions, and has enormous impacts on extensive livestock production by reducing outputs as well as by generating short-term farm decapitalisation (e.g. when livestock die). Since rural people rely on animal husbandry for their livelihood, productive losses become a social problem. Approaches to deal with drought have generally been focused on the livestock–range management linkage, with many suggestions originating from different disciplines. However, fewer efforts had been made to understand the adaptive capacity of households to cope with drought, through changing from on-farm to off-farm approaches. We assessed the implications for household gross income of different smallholder survival strategies, in the context of a severe regional drought. Three strategies were selected: (i) social networks involving partnerships, (ii) income diversification, and (iii) farm production diversification. While drought impacted homogeneously on the production indicators among the different strategies, differences were apparent in household economic performance. Better prices obtained from associated sales and off-farm income strategies registered better household gross income levels. For these cases the effect of drought on farm productivity could be decoupled from household income. Results provide new insights in understanding the social impact of drought on rangelands, challenging current ideas about how governments can support poorest and most vulnerable farmers in rural arid and semi-arid regions.
Hypergraphs and Ramseyian theorems
Authors: Chvátal V.
Published: June 2010

A

k
k

-graph is an ordered couple

(
V
,
E
)

(V,E)

where

V
V

is a set and

E
E

a set of

k
k

-tuples of elements of

V
V

; thus, a

2
2

-graph is an ordinary graph. If the notions of the independent set and the chromatic number are generalized for

k
k

-graphs then one can ask what is the least number of edges in a

k
k

-graph having

p
p

vertices and no independent set of size

b
b

(the problem of Turán) and what is the least number of edges in a

k
k

-graph whose chromatic number exceeds a given number (the generalized problem of Erdös and Hajnal). As in graphs, there is a relationship between independent sets and chromatic numbers—actually, our results for the first problem are applicable to the second one. The theorems of Ramsey’s type are, in fact, theorems on the chromatic number of certain

k
k

-graphs; thus, the results for the problem of Erdös and Hajnal yield lower bounds for the general “Ramseyian numbers".
On the order of the error function fo the 𝑘-free integers
Authors: Suryanarayana D. , Sitaramachandra Rao R.
Published: June 2010

Let

Δ
k

(
x
)

{\Delta _k}(x)

and

Δ
k

′

(
x
)

{\Delta _k}’ (x)

be the error functions in the asymptotic formulae for the number and the sum of

k
k

-free integers

≦
x

\leqq x

. On the assumption of the Riemann hypothesis, we prove the following results by elementary methods:
\[
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="normal upper Delta prime Subscript k Baseline left-parenthesis x right-parenthesis minus x normal upper Delta Subscript k Baseline left-parenthesis x right-parenthesis equals upper O left-parenthesis x Superscript 1 plus 3 slash left-parenthesis 4 k plus 1 right-parenthesis plus epsilon Baseline right-parenthesis">

Δ
k

′

(
x
)
−
x

Δ
k

(
x
)
=
O
(

x

1
+
3

/

(
4
k
+
1
)
+
ε

)

{\Delta _k}’ (x) - x{\Delta _k}(x) = O({x^{1 + 3/(4k + 1) + \varepsilon }})

\]
and
\[
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="StartFraction 1 Over x EndFraction integral Subscript 1 Superscript x Baseline normal upper Delta Subscript k Baseline left-parenthesis t right-parenthesis d t equals upper O left-parenthesis x Superscript 3 slash left-parenthesis 4 k plus 1 right-parenthesis epsilon Baseline right-parenthesis comma">

1
x

∫
1
x

Δ
k

(
t
)
d
t
=
O
(

x

3

/

(
4
k
+
1
)
ε

)
,

\frac {1}{x}\int _1^x {{\Delta _k}(t)dt = O({x^{3/(4k + 1)\varepsilon }}),}

\]
where

ε
>
0

\varepsilon > 0

.
Zero divisors and nilpotent elements in power series rings
Authors: Fields David E.
Published: June 2010

It is well known that a polynomial

f
(
X
)

f(X)

over a commutative ring

R
R

with identity is nilpotent if and only if each coefficient of

f
(
X
)

f(X)

is nilpotent; and that

f
(
X
)

f(X)

is a zero divisor in

R
[
X
]

R[X]

if and only if

f
(
X
)

f(X)

is annihilated by a nonzero element of

R
R

. This paper considers the problem of determining when a power series

g
(
X
)

g(X)

over

R
R

is either nilpotent or a zero divisor in

R
[
[
X
]
]

R[[X]]

. If

R
R

is Noetherian, then

g
(
X
)

g(X)

is nilpotent if and only if each coefficient of

g
(
X
)

g(X)

is nilpotent; and

g
(
X
)

g(X)

is a zero divisor in

R
[
[
X
]
]

R[[X]]

if and only if

g
(
X
)

g(X)

is annihilated by a nonzero element of

R
R

. If

R
R

has positive characteristic, then

g
(
X
)

g(X)

is nilpotent if and only if each coefficient of

g
(
X
)

g(X)

is nilpotent and there is an upper bound on the orders of nilpotency of the coefficients of

g
(
X
)

g(X)

. Examples illustrate, however, that in general

g
(
X
)

g(X)

need not be nilpotent if there is an upper bound on the orders of nilpotency of the coefficients of

g
(
X
)

g(X)

, and that

g
(
X
)

g(X)

may be a zero divisor in

R
[
[
X
]
]

R[[X]]

while

g
(
X
)

g(X)

has a unit coefficient.
A general differential equation for classical polynomials
Authors: Nath B.
Published: June 2010

Agrawal and Khanna [1] have derived the two partial differential equations satisfied by the polynomial set

B
n

(
x
,
y
)

{B_n}(x,y)

. In this paper we shall present a generalization of these results.
Minimal immersions of 2-spheres in 𝑆⁴
Authors: Ruh Ernst A.
Published: June 2010

The classification of isolated singularities of minimal varieties leads to the study of minimal manifolds in the

n
n

-sphere. The object of this paper is to show that a minimal

2
2

-sphere in

S
4

{S^4}

with trivial normal bundle is the standard

2
2

-sphere.
Developable spaces and 𝑝-spaces
Authors: Kullman David E.
Published: June 2010

In this paper it is shown that the following statements are equivalent, for a completely regular space

X
X

. (i)

X
X

is a developable space. (ii)

X
X

is a strict

p
p

-space with a

G
¯

δ

{\bar G_\delta }

-diagonal. (iii)

X
X

is a

θ
\theta

-refinable

p
p

-space with a

G
δ

{G_\delta }

-diagonal.
The projective resolution of a compact space
Authors: Hager Anthony W.
Published: June 2010

A new proof is given of Gleason’s Theorem that in the category of compact Hausdorff spaces and continuous maps, each space has an essentially unique (minimal) projective resolution.
No topologies characterize differentiability as continuity
Authors: Geroch Robert , Kronheimer Erwin , McCarty George
Published: June 2010

Do there exist topologies

U

\mathcal {U}

and

V

\mathcal {V}

for the set

R
R

of real numbers such that a function

f
f

from

R
R

to

R
R

is smooth in some specified sense (e.g., differentiable,

C
n

{C^n}

, or

C
∞

{C^\infty }

) with respect to the usual structure of the real line if and only if

f
f

is continuous from

U

\mathcal {U}

to

V

\mathcal {V}

? We show that the answer is no.
A note on stable homeomorphisms of infinite-dimensional manifolds
Authors: Wong Raymond Y. T.
Published: June 2010

In papers by R. D. Anderson and R. Wong, respectively, it is shown that all homeomorphisms of the Hilbert cube onto itself, or of the infinite dimensional separable Hilbert space

l
2

{l_2}

onto itself, are stable in the sense of Brown-Gluck. These facts can be used to show that all homeomorphisms of

X
X

onto itself are isotopic to the identity mapping where

X
X

is either the Hilbert cube or

l
2

{l_2}

. It follows that some versions of the infinite-dimensional annulus conjecture are true. In this note we give a simple proof of Anderson’s result. It follows from Brown-Gluck’s technique that for any connected manifold

X
X

modeled on

Q
Q

or

s
s

, every homeomorphism of

X
X

onto itself is stable.
A comparision lemma for higher order trajectory derivatives
Authors: Gunderson R. W.
Published: June 2010

A basic result from higher order differential inequalities is used to obtain a comparison lemma, useful when higher order trajectory derivatives of Liapunov functions are known.
Nontangential interpolating sequences and interpolation by normal functions
Authors: Tse Kam-fook
Published: June 2010

The first part of the paper shows that a sequence of points in the unit disk of the complex plane, tending nontangentially to a point on the unit circle, is an interpolating sequence if and only if the pseudo-hyperbolic distance between any pair of points in the sequence is bounded away from zero. The second part shows that interpolating sequences for bounded analytic functions are also interpolating sequences for normal functions.
The parabola theorem for continued fractions over a vector space
Authors: Roach F. A.
Published: June 2010

In a recent paper, we defined a type of reciprocal for points of a real inner product space and considered continued fractions based on this reciprocal. These continued fractions were analogous to ordinary continued fractions in which each partial numerator is unity. In the present paper, we develop a type of continued fraction which is analogous to an ordinary continued fraction of the form in which each partial denominator is unity. The main result is a convergence theorem for such continued fractions which is a direct extension of a theorem by W. T. Scott and H. S. Wall (the Parabola Theorem).
The Arens product and duality in 𝐵*-algebras. II
Authors: Wong Pak-ken
Published: June 2010

Let

A
A

be a commutative

B
∗

{B^ \ast }

-algebra,

Φ
\Phi

its carrier space and

A
∗

{A^ \ast }

the conjugate space of

A
A

. Let

A
′

A’

be the closed subspace of

A
∗

{A^ \ast }

spanned by

Φ
\Phi

. We show that

A
A

is a dual algebra if and only if

A
′

=

A
∗

A’ = {A^ \ast }

and for each

x
∈
A

x \in A

, the mapping

T
x

:
f
→
f
∗
x

{T_x}:f \to f \ast x

is a weakly completely continuous operator on

A
∗

{A^ \ast }

. This improves an early result by B. J. Tomiuk and the author. A similar result holds for general

B
∗

{B^ \ast }

-algebras.
The commutator subgroups of the alternating knot groups
Authors: Murasugi Kunio
Published: June 2010

The aim of this paper is to show that the commutator subgroup of the alternating knot group is the (proper or improper) free product of free groups with isomorphic subgroups amalgamated.
On the Lie algebra of a Burnside group of exponent 5
Authors: Krause Eugene F. , Weston Kenneth W.
Published: June 2010

A. Kostrikin proved that

R
(
5
,
2
)

R(5,2)

has order at most 5

34

^{34}

and is nilpotent of class at most 13. He verified this by showing that the freest Lie ring

L
L

on 2 generators of characteristic 5 which satisfies the 4th Engel condition must be nilpotent of class at most 13. He then appealed to the correspondence between Lie rings and groups, given by the associated Lie ring of a group, to complete his proof. We studied Kostrikin’s calculations and considered a collection of matrices based on them. From these, we were able to construct

L
L

with the use of a Univac 1107 computer and verify that

L
L

is nilpotent of class exactly 13 with order exactly 5

34

^{34}

. Hence, modulo the conjecture made by Kostrikin, Sanov and others that

L
L

is the associated Lie ring of

R
(
5
,
2
)

R(5,2)

, the order of

R
(
5
,
2
)

R(5,2)

is exactly 5

34

^{34}

.