bluuebunny/crossref_metadata_2025 huggingface dataset:
Recast Density and Acquisition of Novel Irregular Past Tense Verbs
Authors: Proctor-Williams Kerry , Fey Marc E.
Published: August 2007

Purpose

Children with specific language impairment (SLI) lag behind children with typical language (TL) in their grammatical development, despite equivalent early exposure to recasts in conversation (M. E. Fey, T. E. Krulik, D. F. Loeb, & K. Proctor-Williams, 1999) and the ability to learn from recasts in intervention as quickly as do children with TL (K. E. Nelson, S. Camarata, J. Welsh, L. Butovsky, & M. Camarata, 1996). This experiment tested whether this apparent paradox could be attributed to variations in the density of recasts in conversation versus intervention.

Method

Thirteen children (7–8 years of age) with SLI and 13 language-similar children (5–6 years of age) with TL were exposed to 3 recast densities of novel irregular past tense verbs (none, conversation-like, intervention-like) over 5 sessions. Outcomes were based on spontaneous conversational productions and a post-test probe.

Results

As predicted, at conversation-like densities, children with TL more accurately produced the target verbs they heard in recasts than in nonrecast models (
d
= 0.58), children with SLI showed no differences, and children with TL produced the verbs more accurately than did children with SLI (
d
= 0.54). Contrary to expectations, at higher intervention-like recast densities, the SLI group did not improve their accuracy, and the TL group performances were significantly poorer (
d
= 0.47).

Conclusion

At conversational levels, recasts facilitated greater verb learning than models alone but only in the TL group. Increasing recast density to the modest levels in this brief intervention experiment did not benefit children with SLI and led to poorer learning for children with TL. To optimize learning, efficiency of recast distribution as well as rate must be considered.
Language Delay and Behavioral/Emotional Problems in Toddlers: Findings From Two Developmental Clinics
Authors: Rescorla Leslie , Ross Gail S. , McClure Sarah
Published: August 2007

Purpose

The association between language delay and behavior problems in toddlers was examined in 2 studies, 1 conducted in a developmental clinic in New Jersey (Study 1;N= 83) and the other conducted in a developmental clinic in New York (Study 2;N= 103).

Method

In both clinics, parents of 18- to 35-month-olds completed the Language Development Survey (LDS) and the Child Behavior Checklist/1.5-5 (CBCL). In Study 2, the Preschool Language Scale–Fourth Edition (PLS-4) was also administered. Neurodevelopmental delay (ND) and pervasive developmental disorder (PDD) symptoms were also assessed in both studies but were done so using different measures.

Results

In Study 1, LDS Vocabulary score and CBCL Total Problems, Internalizing, and Withdrawn scores were significantly correlated. However, when children with ND and/or suspected PDD were excluded, only the correlation between LDS Vocabulary and Withdrawn remained significant. In Study 2, only the correlation between LDS Vocabulary and Withdrawn approached significance. Children delayed in language on the PLS-4 had higher CBCL scores than typically developing toddlers only on the CBCL Withdrawn syndrome.

Conclusion

Significant associations between language delays and behavior problems were not found in 2 samples of 18- to 35-month-olds when children with ND and PDD were excluded, except that toddlers with language delays appeared to show elevated social withdrawal relative to typically developing toddlers.
Linear-scaling method for calculating nuclear magnetic resonance chemical shifts using gauge-including atomic orbitals within Hartree-Fock and density-functional theory
Authors: Kussmann Jörg , Ochsenfeld Christian
Published: August 2007

Details of a new density matrix-based formulation for calculating nuclear magnetic resonance chemical shifts at both Hartree-Fock and density functional theory levels are presented. For systems with a nonvanishing highest occupied molecular orbital–lowest unoccupied molecular orbital gap, the method allows us to reduce the asymptotic scaling order of the computational effort from cubic to linear, so that molecular systems with 1000 and more atoms can be tackled with today’s computers. The key feature is a reformulation of the coupled-perturbed self-consistent field (CPSCF) theory in terms of the one-particle density matrix (D-CPSCF), which avoids entirely the use of canonical MOs. By means of a direct solution for the required perturbed density matrices and the adaptation of linear-scaling integral contraction schemes, the overall scaling of the computational effort is reduced to linear. A particular focus of our formulation is to ensure numerical stability when sparse-algebra routines are used to obtain an overall linear-scaling behavior.
Kinetics of the shear-induced isotropic-to-lamellar transition of an amphiphilic model system: A nonequilibrium molecular dynamics simulation study
Authors: Guo Hongxia , Kremer Kurt
Published: August 2007

The shear-induced isotropic-to-lamellar phase transition in the amphiphilic systems in the vicinity of the quiescent order-to-disorder transition point is investigated by the large-scale parallel nonequilibrium molecular dynamics simulations of simple amphiphilic model systems. There is a shear-induced upward shift of the ordering temperature. The initial isotropic phase orders into a lamellar phase perpendicular to the shear vorticity. The phase diagram as a function of temperature and shear rate is established. The dependency of the ordering transition on interaction strength and shear rate is rationalized by the competition between shear rate and chain relaxation. The time evolution of morphology reveals that the shear-induced ordering proceeds via nucleation and growth, a signature of a first-order phase transition. At low shear rate, a single ordered domain grows after an incubation period. With increasing shear rate ordering speeds up, but eventually develops in a lamellar system with disordered shear bands. The time dependence of the order parameter follows that of the mean-squared end-to-end distance, shear viscosity, and bulk pressure, and follows an Avrami scheme with an Avrami exponent between 2 and 4.
Spin amplification in solution magnetic resonance using radiation damping
Authors: Walls Jamie D. , Huang Susie Y. , Lin Yung-Ya
Published: August 2007

The sensitive detection of dilute solute spins is critical to biomolecular NMR. In this work, a spin amplifier for detecting dilute solute magnetization is developed using the radiation damping interaction in solution magnetic resonance. The evolution of the solvent magnetization, initially placed along the unstable −ẑ direction, is triggered by the radiation damping field generated by the dilute solute magnetization. As long as the radiation damping field generated by the solute is larger than the corresponding thermal noise field generated by the sample coil, the solute magnetization can effectively trigger the evolution of the water magnetization under radiation damping. The coupling between the solute and solvent magnetizations via the radiation damping field can be further improved through a novel bipolar gradient scheme, which allows solute spins with chemical shift differences much greater than the effective radiation damping field strength to affect the solvent magnetizations more efficiently. Experiments performed on an aqueous acetone solution indicate that solute concentrations on the order of 10−5 that of the solvent concentration can be readily detected using this spin amplifier.
The dissociation energy of the new diatomic molecules SiPb and GePb
Authors: Ciccioli A. , Gigli G. , Meloni Giovanni , Testani E.
Published: August 2007

The diatomic molecules SiPb and GePb were for the first time identified by producing high temperature vapors of the constituent pure elements in a “double-oven-like” molecular-effusion assembly. The partial pressures of the atomic, heteronuclear, and homonuclear gaseous species observed in the vapor, namely, Si, Ge, Pb, SiPb, GePb, Pb2, Gen, and Sin (n=2–3), were mass-spectrometrically measured in the overall temperature ranges 1753–1961K (Ge–Pb) and 1992–2314K (Si–Pb). The dissociation energies of the new species were determined by second- and third-law analyses of both the direct dissociation reactions and isomolecular exchange reactions involving homonuclear molecules. The selected values of the dissociation energies at 0K (D0°) are 165.1±7.3 and 141.6±6.9kJ∕mol, respectively, for SiPb and GePb, and the corresponding enthalpies of formation (ΔfH0°) are 476.4±7.3 and 419.3±6.9kJ∕mol. The ionization efficiency curves of the two species were measured, giving the following values for the first ionization energies: 7.0±0.2eV (SiPb) and 7.1±0.2eV (GePb). A computational study of the species SiPb and GePb was also carried out at the CCSD(T) level of theory using the relativistic electron core potential approach. Molecular parameters, adiabatic ionization energies, adiabatic electron affinities, and dissociation energies of the title species were calculated, as well as the enthalpy changes of the exchange reactions involving the other Pb-containing diatomics of group 14. Finally, a comparison between the experimental and theoretical results is presented, and from a semiempirical correlation the unknown dissociation energies of the SiSn and PbC molecules are predicted as 234±7 and 185±11kJ∕mol, respectively.
Calculation of the band structure of polyguanilic acid in the presence of water and Na+ ions
Authors: Ladik J. , Bende A. , Bogar F.
Published: August 2007

Using the Hartree-Fock crystal orbital method with a combined symmetry (helix) operation, the band structure of polyguanilic acid was calculated in the presence of water and Na+ ions. The water structure was optimized with the help of molecular mechanics.The obtained band structure shows that both the valence and conduction bands are purely guanine type. The three impurity bands in the 10.66eV large gap are close to the conduction band and therefore cannot play any role in the assumed hole conduction of the system. Namely, according to detailed x-ray diffraction investigations of the nucleosomes in chromatin, there are possibilities of charge transfer from the negative sites of DNA to the positive ones in histones. Therefore most probably there is a hole conduction in DNA and an electronic one in the histone proteins.
van der Waals forces in presence of free charges: An exact derivation from equilibrium quantum correlations
Authors: Alastuey A. , Cornu F. , Martin Ph. A.
Published: August 2007

We study interatomic forces in a fluid consisting of a mixture of free charges and neutral atoms in the framework of the quantum many-body problem at nonzero temperature and nonzero density. Of central interest is the interplay between van der Waals forces and screening effects due to free charges. The analysis is carried out in a partially recombined hydrogen plasma in the Saha regime. The effective potentials in the medium between two atoms, or an atom and a charge, or two charges, are determined from the large-distance behavior of equilibrium proton-proton correlations. We show, in a proper low-temperature and low-density scaling limit, that those potentials all decay as r−6 at large distance r, while the corresponding amplitudes are calculated exactly. In particular, the presence of free charges only causes a partial (nonexponential) screening of the atomic potential, and it does not modify its typical r−6 decay. That potential reduces to the standard van der Waals form for two atoms in vacuum when the temperature is driven to zero. The analysis is based on first principles: it does not assume preformed atoms and takes into account in a coherent way all effects, quantum mechanical binding, ionization, and collective screening, which originate from the Coulomb potential. Our method relies on the path integral representation of the quantum Coulomb gas.
Rotational spectra of the van der Waals complexes of molecular hydrogen and OCS
Authors: Yu Zhenhong , Higgins Kelly J. , Klemperer William , McCarthy Michael C. , Thaddeus Patrick , Liao Kristine , Jäger Wolfgang
Published: August 2007

The a- and b-type rotational transitions of the weakly bound complexes formed by molecular hydrogen and OCS, para-H2–OCS, ortho-H2–OCS, HD–OCS, para-D2–OCS, and ortho-D2–OCS, have been measured by Fourier transform microwave spectroscopy. All five species have ground rotational states with total rotational angular momentum J=0, regardless of whether the hydrogen rotational angular momentum is j=0 as in para-H2, ortho-D2, and HD or j=1 as in ortho-H2 and para-D2. This indicates quenching of the hydrogen angular momentum for the ortho-H2 and para-D2 species by the anisotropy of the intermolecular potential. The ground states of these complexes are slightly asymmetric prolate tops, with the hydrogen center of mass located on the side of the OCS, giving a planar T-shaped molecular geometry. The hydrogen spatial distribution is spherical in the three j=0 species, while it is bilobal and oriented nearly parallel to the OCS in the ground state of the two j=1 species. The j=1 species show strong Coriolis coupling with unobserved low-lying excited states. The abundance of para-H2–OCS relative to ortho-H2–OCS increases exponentially with decreasing normal H2 component in H2∕He gas mixtures, making the observation of para-H2–OCS in the presence of the more strongly bound ortho-H2–OCS dependent on using lower concentrations of H2. The determined rotational constants are A=22401.889(4)MHz, B=5993.774(2)MHz, and C=4602.038(2)MHz for para-H2–OCS; A=22942.218(6)MHz, B=5675.156(7)MHz, and C=4542.960(7)MHz for ortho-H2–OCS; A=15970.010(3)MHz, B=5847.595(1)MHz, and C=4177.699(1)MHz for HD–OCS; A=12829.2875(9)MHz, B=5671.3573(7)MHz, and C=3846.7041(6)MHz for ortho-D2–OCS; and A=13046.800(3)MHz, B=5454.612(2)MHz, and C=3834.590(2)MHz for para-D2–OCS.
X-ray and ultraviolet photoelectron spectroscopy measurements of Cu-doped CdTe(111)-B: Observation of temperature-reversible CuxTe precipitation and effect on ionization potential
Authors: Teeter Glenn
Published: August 2007

Temperature-programmed x-ray photoelectron spectroscopy (TP-XPS) and ultraviolet photoelectron spectroscopy (UPS) measurements of CdTe(111)-B are used to probe changes to the surface electronic structure that accompany heavy Cu dopant levels and CuxTe precipitation. UPS measurements reveal that the ionization potential of the heavily Cu-doped substrate is only slightly smaller than that of the undoped material. Also, temperature-reversible CuxTe precipitation is observed, which lowers the ionization potential of the surface from 5.7 eV to 4.8 eV. These results suggest that interfacial CuxTe precipitation might play a key role in ohmic-contact formation in CdTe-based photovoltaic devices.
Digital switch and femtotesla magnetic field sensor based on Fano resonance in a spin field effect transistor
Authors: Wan J. , Cahay M. , Bandyopadhyay S.
Published: August 2007

We show that a spin field effect transistor, realized with a semiconductor quantum wire channel sandwiched between half-metallic ferromagnetic contacts, can have Fano resonances in the transmission spectrum. These resonances appear because the ferromagnets are half-metallic, so that the Fermi level can be placed above the majority but below the minority spin band. In that case, the majority spins will be propagating, but the minority spins will be evanescent. At low temperatures, the Fano resonances can be exploited to implement a digital binary switch that can be turned on or off with a very small gate voltage swing of few tens of microvolts, leading to extremely small dynamic power dissipation during switching. An array of 500 000×500 000 such transistors can detect ultrasmall changes in a magnetic field with a sensitivity of 1 fT∕Hz, if each transistor is biased near a Fano resonance.
Enhanced photoluminescence from nanopatterned carbon-rich silicon grown by solid-phase epitaxy
Authors: Rotem Efraim , Shainline Jeffrey M. , Xu Jimmy M.
Published: August 2007

Photoluminescence from the dicarbon G center in nanopatterned silicon is investigated. Enrichment of silicon with carbon atoms has been achieved by solid-phase epitaxy. When this carbon enrichment is combined with nanopatterning, The authors found a 33-fold increase in the G line emission intensity to a level that is comparable to the band-edge photoluminescence. Significant linewidth broadening is observed and is attributed to lattice strain associated with the nanopatterning.
Mechanisms behind blue, green, and red photoluminescence emissions in CaWO4 and CaMoO4 powders
Authors: Campos A. B. , Simões A. Z. , Longo E. , Varela J. A. , Longo V. M. , de Figueiredo A. T. , De Vicente F. S. , Hernandes A. C.
Published: August 2007

A combined experimental and theoretical study was conducted to analyze the photoluminescence (PL) properties of ordered and disordered CaWO4 (CW) and CaMoO4 (CM) powders. Two mechanisms were found to be responsible for photoluminescence emission in CW and CM powders. The first one, in the disordered powders, was caused by oxygen complex vacancies [MO3∙VOx], [MO3∙VO•] and [MO3∙VO••], where M=W or Mo, which leads to additional levels in the band gap. The second mechanism, in ordered powders, was caused by an intrinsic slight distortion of the [WO4] or [MoO4] tetrahedral in the short range.
Experimental study for the conditions of analog switching in ferroelectric liquid crystal cells
Authors: Manjuladevi V. , Panarin Yu. P. , Vij J. K.
Published: August 2007

The authors study the effect of the spontaneous polarization (PS) of a ferroelectric liquid crystal mixture with compensated helix and of the thickness of the alignment layer (da) on the analog switching in a cell. The quality of analog switching is established in terms of its contrast ratio, texture in the dark state, and the electrostatic energy. The latter approximates to PS2da for da⪡d (thickness of the ferroelectric liquid crystal cell layer).
Secondary electron imaging at gas pressures in excess of 1kPa
Authors: Toth Milos , Uncovsky Marek , Ralph Knowles W. , Baker Francis S.
Published: August 2007

Environmental scanning electron microscopy (ESEM) enables electron imaging of gas-mediated, direct-write nanolithography processes, liquids, and hydrated biomaterials. However, ESEM is limited by poor image quality at gas pressures in excess of ∼600Pa. Here the authors achieve high quality secondary electron imaging at 2kPa of H2O by optimizing boundary conditions that govern beam scatter and the energy distribution of low energy electrons in the gas, dielectric breakdown of the gas, and detector collection efficiency. The presented high pressure imaging method will enable imaging of hydrated materials at close to room temperature, and gas-mediated surface modification processes occurring at high pressures.
Laser induced short plane acoustic wave focusing in water
Authors: Ko Seung H. , Ryu Sang G. , Misra Nipun , Pan Heng , Grigoropoulos Costas P. , Kladias Nick , Panides Elias , Domoto Gerald A.
Published: August 2007

Laser induced high frequency acoustic wave generation, propagation, and focusing in water are studied. A large area, flat, and short duration acoustic wave was generated by the thermoelastic interaction of a homogenized short pulsed laser beam with the liquid-solid interface and propagated at the speed of sound. Laser flash Schlieren photography was used to visualize the transient interaction of the flat acoustic wave with a cylindrical concave lens and the subsequent acoustic wave focusing. Numerical simulations showed the acoustic wave could be focused to several tens of microns in size and 7bars in pressure.
Cactus Carvings and Desert Defecations: Embodying Representations of Border Crossings in Protected Areas on the Mexico—US Border
Authors: Sundberg Juanita , Kaserman Bonnie
Published: August 2007

Recent strategies to enforce the United States boundary with Mexico have shifted undocumented immigrants into remote lands federally designated as protected areas (as in national park or national wildlife refuge). Government and media institutions represent such entries as a threat to nature. In this paper we argue that representations and interpretations of threats to nature in border-protected areas are laden with identity attachments. In repeatedly defining that which is threatened as ‘American’, such discourses work to draw boundaries around the nation, thereby narrating inclusion and exclusion.
Histone modifications induced by a family of bacterial toxins
Authors: Hamon Mélanie Anne , Batsché Eric , Régnault Béatrice , Tham To Nam , Seveau Stéphanie , Muchardt Christian , Cossart Pascale
Published: August 2007

Upon infection, pathogens reprogram host gene expression. In eukaryotic cells, genetic reprogramming is induced by the concerted activation/repression of transcription factors and various histone modifications that control DNA accessibility in chromatin. We report here that the bacterial pathogenListeria monocytogenesinduces a dramatic dephosphorylation of histone H3 as well as a deacetylation of histone H4 during early phases of infection. This effect is mediated by the major listerial toxin listeriolysin O in a pore-forming-independent manner. Strikingly, a similar effect also is observed with other toxins of the same family, such asClostridium perfringensperfringolysin andStreptococcus pneumoniaepneumolysin. The decreased levels of histone modifications correlate with a reduced transcriptional activity of a subset of host genes, including key immunity genes. Thus, control of epigenetic regulation emerges here as an unsuspected function shared by several bacterial toxins, highlighting a common strategy used by intracellular and extracellular pathogens to modulate the host response early during infection.
Elevated NMDA receptor levels and enhanced postsynaptic long-term potentiation induced by prenatal exposure to valproic acid
Authors: Rinaldi Tania , Kulangara Karina , Antoniello Katia , Markram Henry
Published: August 2007

Valproic acid (VPA) is a powerful teratogen causing birth defects in humans, including autism spectrum disorder (ASD), if exposure occurs during the first trimester of embryogenesis. Learning and memory alterations are common symptoms of ASD, but underlying molecular and synaptic alterations remain unknown. We therefore studied plasticity-related mechanisms in the neocortex of 2-week-old rats prenatally exposed to VPA and tested for changes in glutamate-mediated transmission and plasticity in the neocortex. We found a selective overexpression of NR2A and NR2B subunits of NMDA receptors, as well as the commonly linked kinase calcium/calmodulin-dependent protein kinase II. Synaptic plasticity experiments between pairs of pyramidal neurons revealed an augmented postsynaptic form of long-term potentiation. These results indicate that VPA significantly enhances NMDA receptor-mediated transmission and causes increased plasticity in the neocortex. Enhanced plasticity introduces a surprising perspective to the potential molecular and synaptic mechanisms involved in children prenatally exposed to VPA.
Dominant-negative DISC1 transgenic mice display schizophrenia-associated phenotypes detected by measures translatable to humans
Authors: Hikida Takatoshi , Jaaro-Peled Hanna , Seshadri Saurav , Oishi Kenichi , Hookway Caroline , Kong Stephanie , Wu Di , Xue Rong , Andradé Manuella , Tankou Stephanie , Mori Susumu , Gallagher Michela , Ishizuka Koko , Pletnikov Mikhail , Kida Satoshi , Sawa Akira
Published: August 2007

Here, we report generation and characterization of Disrupted-In-Schizophrenia-1 (DISC1) genetically engineered mice as a potential model for major mental illnesses, such as schizophrenia. DISC1 is a promising genetic risk factor for major mental illnesses. In this transgenic model, a dominant-negative form of DISC1 (DN-DISC1) is expressed under the αCaMKII promoter.
In vivo
MRI of the DN-DISC1 mice detected enlarged lateral ventricles particularly on the left side, suggesting a link to the asymmetrical change in anatomy found in brains of patients with schizophrenia. Furthermore, selective reduction in the immunoreactivity of parvalbumin in the cortex, a marker for an interneuron deficit that may underlie cortical asynchrony, is observed in the DN-DISC1 mice. These results suggest that these transgenic mice may be used as a model for schizophrenia. DN-DISC1 mice also display several behavioral abnormalities, including hyperactivity, disturbance in sensorimotor gating and olfactory-associated behavior, and an anhedonia/depression-like deficit.
Cardiotoxicity of Ma Huang/Caffeine or Ephedrine/Caffeine in a Rodent Model System
Authors: Dunnick J. K. , Kissling G. , Gerken D. K. , Vallant M. A. , Nyska A.
Published: August 2007

Ma Huang (equivalent to 0, 12.5, 25, or 50 mg/kg ephedrine) or ephedrine (0, 6.25, 12.5, 25 mg/kg) were administered as one bolus oral dose to male F344 rats with and without caffeine. The herbal medicine Ma Huang (ephedra) in combination with caffeine caused rapid clinical signs of toxicity including salivation, hyperactivity, ataxia, and eventually lethargy, and failure to respond to stimuli. When this syndrome of clinical signs emerged, animals were moribund sacrificed, and a histological analysis for heart lesions performed. Cardiotoxicity included hemorrhage, necrosis, and degeneration in the ventricles or interventricular septum within 2–4 hours after treatment with Ma Huang (ephedra)/caffeine or ephedrine (the principal active component in Ma Huang)/caffeine. There was a steep dose response curve for cardiotoxicity with minimal toxicity seen at levels of Ma Huang (equivalent to 12.5 mg/kg ephedrine) with caffeine. However, cardiotoxic lesions occurred in 28% of animals with Ma Huang dosages equivalent to 25 mg/kg ephedrine with 15 or 30 mg/kg caffeine, and in 90% of animals at Ma Huang exposures equivalent to 50 mg/kg ephedrine with 15 or 30 mg/kg caffeine. Cardiotoxic lesions occurred in 47% of animals in the 25 mg/kg ephedrine groups with caffeine at 7.25, 15, or 30 mg/kg. There was no statistical difference in the occurrence of cardiotoxic lesions when 15 or 30 mg/kg caffeine was combined with Ma Huang equivalent to 25 or 50 mg/kg ephedrine; likewise there was no statistical difference in the occurrence of cardiotoxic lesions when 7.25, 15, or 30 mg/kg caffeine was combined with 25 mg/kg ephedrine. These results show that the cardiotoxic effects of the herbal medicine, Ma Huang, are similar to that of ephedrine, the principal active ingredient in the herbal medicine. The combination of Ma Huang or ephedrine with caffeine enhanced the cardiotoxicity over that with the herbal medicine or the active ingredient alone.
Resource Wealth and the Risk of Civil War Onset: Results from a New Dataset of Natural Resource Rents, 1970—1999
Authors: De Soysa Indra , Neumayer Eric
Published: August 2007

The existing literature identifies natural resource wealth as a major determinant of civil war. The dominant causal link is that resources provide finance and motive (the “looting rebels” model). Others see natural resources as causing “political Dutch disease,” which in turn weakens state capacity (the “state capacity” model). In the looting rebels model, resource wealth first increases, but then decreases the risk for civil war as very large wealth enables governments to constrain rebels, whereas in the state capacity model, large resource wealth is unambiguously related to higher risk of war. This research note uses a new dataset on natural resource rents that are disaggregated as mineral and energy rents for addressing the resources-conflict relationship. We find that neither a dummy variable for major oil exporters nor our resource rents variables predict civil war onset with a 1000-battle-death threshold coded by Fearon and Laitin (2003) in the period after 1970 for which rents data are available. However, using a lower threshold of 25 battle deaths, we find that energy wealth, but not mineral wealth, increases the risk for civil war onset. We find no evidence for a nonlinear relationship between either type of resources and civil war onset. The results tentatively support theories built around state capacity models and provide evidence against the looting rebels model of civil war onset.
2006 HES Presidential address a Tale of two Mainstreams: Economics and Philosophy of Natural Science in the Mid-Twentieth Century
Authors: Hands D. Wade
Published: August 2007

HES Presidential addresses often attempt to answer a substantive question (or number of related questions) in the history of economic thought. The answers provided are not “answers” in the sense that one finds an answer to a simple numerical problem; rather they are historical narratives, stories, that bring the listener/reader to a new, and hopefully deeper, understanding of a particular author, piece of economic literature, or episode in the history of economic thought.
The Editor as Scientific Revolutionary: Keynes, The Economic Journal, and the Pigou Affair, 1936–1938
Authors: Aslanbeigui Nahid , Oakes Guy
Published: August 2007

Thus spake Edwin Cannan, professor of economics at the London School of Economics (LSE) and member of the Council of the Royal Economic Society, publisher of The Economic Journal (EJ). From 1911 to 1945, Keynes was editor of the EJ, arguably the most prestigious journal in British economics. At the time of Cannan's remark in February 1934, when the early drafts of The General Theory of Employment, Interest, and Money were taking shape and Keynes had assumed leadership of a movement to reconceptualize economic theory, he not only had ideas of his own but an uncommonly robust sense of their importance. Although Keynes's conception of the ultimate purpose of economic theory remained true to the Marshallian tradition in which he was trained— forging scientific tools to improve the lot of humankind—his immediate objective was less pacific: the destruction of classical economics (Keynes 1935, p. 36). In his metaphor, classicism was a citadel fortified by an invincible superstructure constructed over generations by economists of great theoretical power and ingenuity, from David Ricardo and John Stuart Mill to Alfred Marshall and his own contemporary, Arthur Cecil Pigou. Because the citadel was vulnerable only in its “fundamental groundwork,” an assault would succeed only by undermining this foundation (Keynes 1973a, p. 533).
On the Bicentennial of the other “Inquiry”: Lauderdale's
Authors: Ahmad Syed
Published: August 2007

James Maitland, Lord Lauderdale published his An Inquiry into the Nature and Origin of Public Wealth and into the Means and Causes of its Increase (1804) only twentyeight years after the publication of the “Inquiry”: An Inquiry into the Nature and Causes of the Wealth of Nations, by Adam Smith. A comparison of the titles strongly suggests some relationship, and indeed even glancing through the first few pages of Lauderdale's book confirms this conjecture. The book takes off as a critique of Smith's, and by-and-large remains so till the end. Many of the elements of his criticism can be seen in the difference in the wording of the titles of the two books. Except for “Nations” all the significant words in Smith's title are included in Lauderdale's, but he adds three more: “Origin,” “Means” and “Public” (which is not a substitute for the omitted “Nation”). As we shall see, in his view, ignoring these led to major deficiencies in Smith's work, and Lauderdale set out to point them out, and if possible, to correct them.
William Alonso, Richard Muth, Resources for the Future, and the Founding of Urban Economics
Authors: McDonald John F.
Published: August 2007

Frequent reference is made to the Alonso-Muth model of the urban land and housing markets, and the creation of this model often is considered to be the founding act in the field of urban economics. One purpose of this paper is to examine closely the original writings of these two distinguished authors, William Alonso and Richard Muth, and to show that their contributions to the development of the model were not identical. Both authors focused on the idea that there is a trade-off between access to a central point (for employment) and the price of residential land or housing, but their models were designed to serve somewhat different purposes. A second objective of this paper is to evaluate the proposition that theirs was indeed the founding act in the field by concentrating on the earliest versions of their work on the model, rather than on the enormous literature that followed. See Masahisa Fujita (1989) for a comprehensive treatment of the subsequent theoretical literature that was stimulated by Alonso and Muth.
Confronting HIV/AIDS in a South African village: The impact of health-seeking behaviour 1
Authors: Golooba-Mutebi Frederick , Tollman Stephen M.
Published: August 2007

Much social science research on HIV/AIDS focuses on its impact within affected communities and how people try to cope with its consequences. Based on fieldwork in rural South Africa, this article shows ways in which the inhabitants of a village react to illness, in general, and the role their reactions play in facilitating the spread of communicable diseases such as HIV/AIDS. There is potentially a strong connection between the manner in which people respond to illness in general, and actual transmission of infection. By influencing the way villagers react to episodes of ill health, folk beliefs about illness and illness causation may create avenues for more people to become infected. This suggests that efforts to combat the HIV/AIDS pandemic cannot succeed without tackling the effects of folk beliefs. Therefore, in addressing the problem of HIV/AIDS, experts should focus on more than disseminating information about cause and transmission, and promoting abstinence, safe sex, and other technocratic fixes. Our findings suggest that people need information to facilitate not only decision-making about how to self-protect against infection, but also appropriate responses when infection has already occurred.
Coping with change: Household structure and composition in rural South Africa, 1992 — 20031
Authors: Madhavan Sangeetha , Schatz Enid J.
Published: August 2007

Aim: To describe household change over a 10-year period of tremendous social, political, economic and health transformation in South Africa using data from the Agincourt health and demographic surveillance system in the rural northeast of South Africa. Methods: Examination of household structure and composition at three points: 1992, 1997, and 2003. These three years loosely represent conditions immediately before the elections (1992), short term post-elections (1997), and longer term (2003), and span a period of notable increase in HIV prevalence. Results: Average household size decreased and the proportion headed by females increased. The within-household dependency ratios for children and elders both decreased, as did the proportion of households containing foster children. The proportion with at least one maternal orphan doubled, but was still relatively small at 5.5%. Conclusions: This analysis is a starting point for future investigations aimed at explaining how HIV/AIDS and other sociocultural changes post-apartheid have impacted on household organization. The analysis shows both consistency and change in measures of household structure and composition between 1992 and 2003. The changes do not include an increase in various types of ``fragile families'', such as child-headed or skipped-generation households that might be expected due to HIV/AIDS.
Apolipoprotein E genotypes and their relation to lipid levels in a rural South African population 1
Authors: Masemola Matshane L. , Alberts Marianne , Urdal Petter
Published: August 2007

Aims: Genetic variation at the apolipoprotein E (apoE) locus is an important determinant of plasma lipids. The aim of the present study was to evaluate the association between apolipoprotein E genotype and plasma lipid levels among a rural black population in South Africa. Methods: Lipid levels and apoE genotypes were studied in 505 volunteer subjects (363 women, 142 men) resident in the Dikgale demographic surveillance site. Results: Allele frequencies were found to be 0.190 for ε2, 0.518 for ε3, and 0.293 for ε4, indicating a relatively low frequency of the ε3 allele and a high frequency of the ε4 allele. To determine the effect of apoE polymorphism on lipid levels three groups were formed: namely ε2-, ε3-, and ε4-expressing groups. A significant effect of the apoE genotype on total cholesterol, low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C)/Total cholesterol (TC) ratio, and triglycerides was observed. LDL-C was significantly lower and the HDL-C/TC ratio was significantly higher in the ε2 group compared with the ε3 and ε4 groups. Triglyceride levels were significantly higher in the ε2 group than in the ε3 group. Conclusions: With the unfavourable apoE allele distribution, and the lifestyle changes taking place in rural South African populations, preventive strategies need to be developed to limit a potential epidemic of cardiovascular disease in the black population of South Africa.
Mortality trends in a new South Africa: Hard to make a fresh start1
Authors: Kahn Kathleen , Garenne Michel L. , Collinson Mark A. , Tollman Stephen M.
Published: August 2007

Aims: This paper examines trends in age-specific mortality in a rural South African population from 1992 to 2003, a decade spanning major sociopolitical change and emergence of the HIV/AIDS pandemic. Changing mortality patterns are discussed within a health-transition framework. Methods: Data on population size, structure, and deaths, obtained from the Agincourt health and demographic surveillance system, were used to calculate person-years at risk and death rates. Life tables were computed by age, sex and calendar year. Mortality rates for the early period 1992—93 and a decade later, 2002— 03, were compared. Results: Findings demonstrate significant increases in mortality for both sexes since the mid-1990s, with a rapid decline in life expectancy of 12 years in females and 14 years in males. The increases are most prominent in children (0—4) and young adult (20—49) age groups, in which increases of two- and fivefold respectively have been observed in the past decade. Sex differences in mortality patterns are evident with increases more marked in females in most adult age groups. Conclusions: Empirical data demonstrate a marked ``counter transition'' with mortality increasing in children and young adults, ``epidemiologic polarization'' with vulnerable subgroups experiencing a higher mortality burden, and a ``protracted transition'' with simultaneous emergence of HIV/AIDS together with increasing non-communicable disease in older adults. The health transition in rural South Africa is unlikely to predict patterns elsewhere; hence the need to examine trends in as many contexts as have the data to support such analyses.
Using health and demographic surveillance to understand the burden of disease in populations: The case of tuberculosis in rural South Africa1
Authors: Pronyk Paul M. , Kahn Kathleen , Tollman Stephen M.
Published: August 2007

Aims: To utilize the Agincourt health and demographic surveillance system (HDSS) platform to assess the burden of pulmonary tuberculosis (PTB) in a rural South African sub-district. Methods: During 1999, data from three sources were combined to estimate disease prevalence amongst a non-migrant adult population: (1) passive case-finding (PCF) through hospital register data; (2) active case finding (ACF) using a systematic household assessment of chronic coughers; and (3) verbal autopsy (VA) data on cause of death. Results: Of 66,840 residents, 38,251 permanent adult residents were included in the analysis. A total of 102 cases of PTB were detected through PCF. ACF sweep detected 366 chronic coughers with 6 cases of confirmed PTB. Among 28 PTB deaths detected by VA, 13 (46%) were not previously identified by the health service. The total PTB prevalence was 157/100,000; 110/100,000 of prevalent cases were detected by PCF. Among undetected cases, 24/ 100,000 were identified through ACF, while 23/100,000 were detected by the VA process. Conclusions: Amongst prevalent PTB cases in the permanent adult population, 70% were detected by the health service; 15% of cases were undiagnosed in the community, while an equal proportion died of PTB prior to diagnosis. The latter groups contributed disproportionately to infectiousness in the community through prolonged duration of symptoms. As most of these cases presented to the health service on a number of occasions, strengthening early case detection should remain the cornerstone of TB control efforts. Strategies to strengthen the application of health & demographic surveillance systems to disease surveillance are discussed.
``Locusts are now our beef'': Adult mortality and household dietary use of local environmental resources in rural South Africa1
Authors: Hunter Lori M. , Twine Wayne , Patterson Laura
Published: August 2007

There is currently a lack of research on the association between demographic dynamics and household use of natural resources in rural Africa. Such work is important because in rural Africa natural resources buffer households against shocks, offering both sustenance and income-generating potential. Aims: The article focuses on adult mortality as a household shock, examining use of local environmental resources as related to household dietary needs. Methods: The authors analyze two sources of data collected during May—December 2004 in the MRC/Wits Rural Public Health and Health Transitions Research Unit (Agincourt) in rural South Africa. Quantitative analyses use survey data from 240 households, stratified by adult mortality experience. Qualitative data are based on 31 interviews with members of households having recently experienced adult mortality. Results: The interviews provide insight into a variety of household-level mortality impacts and also suggest the importance of proximate resources in the maintenance of food security following the loss of an adult household member. Quantitatively, there are significant differences, both in patterns of usage of the natural environment and in levels of food security, between households that have lost an adult and those that have not. The association between mortality and household use of local environmental resources is further shaped by the gender of the deceased and the time elapsed since the death. Conclusions: Adult mortality, particularly the death of a male wage-earner, affects household food security. Time allocation is affected as resource collection responsibilities shift, and wild foods may substitute for previously purchased goods.
What's new? Investigating risk factors for severe childhood malnutrition in a high HIV prevalence South African setting1
Authors: Saloojee Haroon , De Maayer Tim , Garenne Michel L. , Kahn Kathleen
Published: August 2007

Aim: To identify risk factors for severe childhood malnutrition in a rural South African district with a high HIV/AIDS prevalence. Design: Case-control study. Setting: Bushbuckridge District, Limpopo Province, South Africa. Participants: 100 children with severe malnutrition (marasmus, kwashiorkor, and marasmic kwashiorkor) were compared with 200 better nourished (>-2 SD weight-for-age) controls, matched by age and village of residence. Bivariate and multivariate analyses were conducted on a variety of biological and social risk factors. Results: HIV status was known only for a minority of cases (39%), of whom 87% were HIV positive, while 45% of controls were stunted. In multivariate analysis, risk factors for severe malnutrition included suspicion of HIV in the family (parents or children) (OR 217.7, 95% CI 22.7—2091.3), poor weaning practices (OR 3.0, 95% CI 2.0—4.6), parental death (OR 38.0, 95% CI 3.8—385.3), male sex (OR 2.7, 95% CI 1.2—6.0), and higher birth order (third child or higher) (OR 2.3, 95% CI 1.0—5.1). Protective factors included a diverse food intake (OR 0.53, 95% CI 0.41—0.67) and receipt of a state child support grant (OR 0.44, 95% CI 0.20—0.97). A borderline association existed for family wealth (OR 0.9 per unit, 95% CI 0.83—1.0), father smoking marijuana (OR 3.9, 95% CI 1.1— 14.5), and history of a pulmonary tuberculosis contact (OR 3.2, 95% CI 0.9—11.0). Conclusions: Despite the increasing contribution of HIV to the development of severe malnutrition, traditional risk factors such as poor nutrition, parental disadvantage and illness, poverty, and social inequity remain important contributors to the prevalence of severe malnutrition. Interventions aiming to prevent and reduce severe childhood malnutrition in high HIV prevalence settings need to encompass the various dimensions of the disease: nutritional, economic, and social, and address the prevention and treatment of HIV/AIDS.
The implications of high-Z first-wall materials on noble gas wall recycling
Authors: Schmid K. , Schwarz-Selinger T. , Jacob W. , Dux R.
Published: August 2007

Recent experiments in ASDEX Upgrade (AUG) have experienced surprisingly high He plasma impurity concentrations. Such high He concentrations have not been observed with C walls, they were only observed since the increase in the W first-wall coverage of ASDEX Upgrade to 85%. The high He plasma concentration appears to be linked to the fraction of W surfaces open to plasma contact that are not covered by boronization layers and to the number of He glow discharges performed for wall conditioning prior to normal plasma operation. This points to the different retention and release properties of W and C for He. To elucidate these differences dedicated laboratory experiments have been performed. To study the retention, different types of W and C targets, including those used in ASDEX Upgrade, were implanted with3He at 200 and 600 eV and the amount of retained He was determined through thermal effusion spectroscopy (TES) and ion beam analysis methods. These experiments showed that W can retain up to 10 times more He than C depending on the energy of the implanted3He. The TES measurement showed that both W and C start to out gas He at ≈400 K which is not reached at the first-wall in AUG. Therefore the differences in the release of He from W and C surfaces due to particle bombardment was investigated.3He implanted W and C substrates were exposed to4He or H2plasmas and the loss of3He was measured. For an H2plasma and 100 eV bias, three times more He is released from W than from C. For4He and 100 eV bias between 2 and 10 times more3He was released from W than from C depending on the type of W and C. The release rate of He from W and C through particle induced release was found to be equal. Therefore the stronger release of He from W can be explained by the higher retention of He in W.
Investigation of resistive wall mode stabilization physics in high-beta plasmas using applied non-axisymmetric fields in NSTX*
Authors: Sontag A.C. , Sabbagh S.A. , Zhu W. , Menard J.E. , Bell R.E. , Bialek J.M. , Bell M.G. , Gates D.A. , Glasser A.H. , LeBlanc B.P. , Shaing K.C. , Stutman D. , Tritz K.L.
Published: August 2007

The National Spherical Torus Experiment (NSTX) offers an operational space characterized by high-beta (βt= 39%, βN> 7,) and low aspect ratio (A> 1.27) to leverage the plasma parameter dependences of RWM stabilization and plasma rotation damping physics giving greater confidence for extrapolation to ITER. Significant new capability for RWM research has been added to the device with the commissioning of a set of six non-axisymmetric magnetic field coils, allowing generation of fields with dominant toroidal mode number,n, of 1–3. These coils have been used to study the dependence of resonant field amplification on applied field frequency and RWM stabilization physics by reducing the toroidal rotation profile below its steady-state value through non-resonant magnetic braking. Modification of plasma rotation profiles shows that rotation outsideq= 2.5 is not required for passive RWM stability and there is large variation in the RWM critical rotation at theq= 2 surface, both of which are consistent with distributed dissipation models.