bluuebunny/crossref_metadata_2025 huggingface dataset:
TWO THEORIES OF ENVIRONMENTAL REGULATION
Authors: Hasnas John
Published: June 2009

The over-exploitation of commonly-held resources is typically analyzed as an instance of market failure that calls for legislation to internalize the social costs that private activities impose on the environment. In this article, I argue that to the extent that this analysis ignores the regulatory effect of the common law, it is unsound. In The Tragedy of the Commons, Garret Hardin points out that there are two solutions to the tragedy: privatize the resource or restrict access to it. Environmental legislation is a means restricting access to the commons. The evolutionary development of common law is a means of privatizing the commons. These represent alternative methods of environmental regulation. Proper public policy analysis requires a comparative assessment of the efficacy of these methods for resolving any particular environmental problem. In many, if not most cases, such an assessment will show common law regulation to be superior to environmental legislation.
THE END OF THE EXTERNALITY REVOLUTION
Authors: Barnett A. H. , Yandle Bruce
Published: June 2009

In the early 1970s, we and others in the economics profession became enamored with the notion of externalties—a cost or benefit imposed on or provided to others but not taken into account by the economic agents who generate the effect. We, and others, seemed to see external effects everywhere. There was polluted water and air, noise, urban blight, traffic congestion, and other features of modern life that seemed to call out for some form of corrective action. As the externalities revolution unfolded, economists and other social scientists overlooked the importance of evolved legal and other institutions that formally and informally establish property and liability rules that cause decision makers to face the cost of their actions, including what otherwise could be external costs imposed on unwilling third parties.

While markets seemed always to fail, political institutions were seen systematically as without blemish, or so it seemed. It was this two-pronged failure, 1) a failure to consider and state assumptions about background institutional arrangements and 2) a disregard for special interest politics, that became the Achilles Heel of the otherwise elegant externality arguments. Eventually, it was the modern institutionalists, scholars who focused on laws, regulation, and rules of the marketplace, who attempted to close the lid and drive the nails on the externality coffin.

In this paper, we reach back to 1920 and trace the rise and decline of the policy importance of externalities theory. Beginning with A. C. Pigou and Alfred Marshall, our story includes some of the great figures in economic history of thought. But while theory was being built, institutions were overlooked. Pigou continues to be a dominant player in the story until the 1960s and 1970s when externalities theory was challenged by James M. Buchanan, Ronald Coase and other scholars. It is here in the twilight years of the externalities revolution that the prospects of government failure are raised as being more daunting than the likelihood of market failure. Finally, in the late 1970s and beyond, the externalities revolution is replaced by a property rights revolution.
FREEDOM AND DEPENDENCY IN AN ENVIRONMENTAL AGE
Authors: Dobson Andrew
Published: June 2009

In this article the implications of our nature as both autonomous and heteronomous beings is discussed. It is suggested that our condition as part-dependent creatures calls for a reconsideration of the nature of both freedom and liberalism, and the work of Alasdair MacIntyre and Jean-Paul Sartre is used to illustrate the natural and historical dimensions of our dependency. The conclusion reached is that neither deep ecological re-enchantment nor full-blooded cornucopianism are possible, and that we need to take our nature as semi-dependent creatures seriously as we seek ways of negotiating our way through our environmental problems.
DO GLOBAL WARMING AND CLIMATE CHANGE REPRESENT A SERIOUS THREAT TO OUR WELFARE AND ENVIRONMENT?
Authors: Mann Michael E.
Published: June 2009

The science underlying global warming, climate change, and the connections between these phenomena are reviewed. Projected future climate changes under various plausible scenarios of future human behavior are explored, as are the potential impacts of projected climate changes on society, ecosystems, and our environment. The economic, security, and ethical considerations relevant to determining the threat posed by climate change are subsequently assessed. The article then discusses the various means available for climate change mitigation, focusing on the relative strengths and weaknesses of various societal alternatives including ‘geoengineering’ and transitioning to less carbon intensive energy sources. The article concludes with the author's views as to what steps might most profitably be taken to avert dangerous anthropogenic interference with Earth's climate, and the ramifications if such steps are not taken.
TAKING PROPERTY RIGHTS SERIOUSLY: THE CASE OF CLIMATE CHANGE
Authors: Adler Jonathan H.
Published: June 2009

The dominant approach to environmental policy endorsed by conservative and libertarian policy thinkers, so-called “free market environmentalism” (FME), is grounded in the recognition and protection of property rights in environmental resources. Despite this normative commitment to property rights, most self-described FME advocates adopt a utilitarian, welfare-maximization approach to climate change policy, arguing that the costs of mitigation measures could outweigh the costs of climate change itself. Yet even if anthropogenic climate change is decidedly less than catastrophic, human-induced climate change is likely to contribute to environmental changes that violate traditional conceptions of property rights. Viewed globally, the actions of some countries—primarily industrialized nations—are likely to increase environmental harms suffered by other countries—less developed nations that have not (as of yet) made any significant contribution to climate change. It may well be that aggregate human welfare would be maximized in a warmer, wealthier world, or that the gains from climate change will offset environmental losses. Yet such claims, even if demonstrated, would not address the normative concern that the consequences of anthropogenic global warming would infringe upon the rights of people in less-developed nations. As a consequence, this paper calls for a rethinking of FME approaches to climate change policy.
SHOULD ENDANGERED SPECIES HAVE STANDING? TOWARD LEGAL RIGHTS FOR LISTED SPECIES
Authors: Callicott J. Baird , Grove-Fanning William
Published: June 2009

The Endangered Species Act of 1973 (ESA) is America's strongest environmental law. Its citizen-suit provision—permitting “any person” whomsoever to sue on behalf of a threatened or endangered species—awards implicit intrinsic value, de facto standing, and operational legal rights (sensu Christopher D. Stone) to listed species. Accordingly, some cases had gone forward in the federal courts in the name of various listed species between 1979 (Palila v. Hawaii Dept. of Land & Natural Resources) and 2004 (Cetacean Community v. Bush), when the Ninth Circuit Court of Appeals ruled that animals could not sue in their own name. Because the Supreme Court has interpreted its habitat destruction as the “taking” of a listed species, some have argued that enforcement of the ESA's critical-habitat-protection provision is a “regulatory taking” of private property without just compensation, contrary to the Fifth Amendment of the Constitution. The courts have not agreed. The ESA citizen-suit provision appears to waive federal-court standing requirements devolved from Article III of the U.S. Constitution, creating much confusion and mutually contradictory rulings. A series of cases (culminating with Bennett v. Spear) reconciles the ESA's citizen-suit provision with the particularized and concrete “injury-in-fact” standing requirements devolved from Article III.
The Role of Human Resource Practices and Group Norms in the Retirement Process
Authors: Potočnik Kristina , Tordera Nuria , Peiró Jose Maria
Published: June 2009

The present study analyzed retirement intentions and behavior as part of a work role withdrawal process. We examined the influences of the organizational and group contexts in the process of work role exit by means of two sources of work role expectations: human resource practices and group norms. Three different types of human resource practices were taken into consideration: performance enhancement practices, retirement enhancement practices, and organizational pressures toward retirement. Furthermore, three types of retirement indicators were analyzed: age considering retirement for the first time, early retirement intentions, and retirement age. Hierarchical regression analyses were carried out on a sample of 270 retirees to test the hypotheses. Results showed that retirement enhancement practices and organizational pressures toward retirement predict all the retirement indicators. Moreover, group norms moderated the relationships between retirement enhancement practices and two out of the three outcomes: age considering retirement for the first time and retirement age. Overall, our findings showed that organizational and group contexts play an important role in the retirement process. Moreover, our results indicate an interaction between organizational and group factors in the work role exit process.
Perceived Work-Related Demands Associated with Social Change, Control Strategies, and Psychological Well-Being
Authors: Pinquart Martin , Silbereisen Rainer K. , Körner Astrid
Published: June 2009

We analyzed whether perceived work-related demands associated with social change (e.g., increased risk of becoming unemployed and more difficulties with long-term career planning) and processes of dealing with work-related demands relate to psychological well-being; and whether these relationships vary by regional economic conditions. A sample of 1,427 employed respondents was interviewed who live in economically healthy versus weak regions of Germany. It was found that higher levels of work-related demands were associated with lower psychological well-being, whereas higher levels of goal engagement in coping with these demands related to higher well-being. Respondents from economically disadvantaged regions perceived higher levels of work-related demands and used more goal engagement control strategies. However, the association of work-related demands with psychological well-being was weaker in economically disadvantaged regions. In addition, associations between perceived work-related demands and goal disengagement on psychological well-being varied by the economic conditions of the region.
Personality Profiles Among Targets and Nontargets of Workplace Bullying
Authors: Lind Karina , Glasø Lars , Pallesen Ståle , Einarsen Ståle
Published: June 2009

This study investigated personality profiles among targets and nontargets of workplace bullying. Personality was assessed by the NEO-FFI, which measures the main dimensions in accordance with the five-factor model of personality: Neuroticism, Extraversion, Conscientiousness, Agreeableness, and Openness. A total of 435 health care employees participated in the study, in which 42 targets of bullying were identified. A logistic regression analysis revealed significant differences between targets and nontargets of workplace bullying on just two of the Big Five dimensions, with targets scoring higher on Conscientiousness and lower on Agreeableness. Further, a cluster analysis showed no subclusters in the target sample regarding personality. The authors, therefore, consider the differences to be minimal. Hence, personality patterns do not easily differentiate targets of workplace bullying from nontargets. One-sided explanations of the bullying phenomenon, such as personality, are, therefore, likely to be inappropriate.
Leaving-Home Patterns in Emerging Adults
Authors: Seiffge-Krenke Inge
Published: June 2009

In a longitudinal study on 93 participants, the relationships between leaving home, developmental task progression, and the amount of parental support were analyzed over a time span of 11 years. Three different leaving-home patterns emerged: on-time leavers, late leavers/returners, and those still residing with their parents at ages 21 to 25. Aspirations with respect to the attainment of developmental tasks specific to adolescence and emerging adulthood did not differ between individuals with different leaving-home patterns. Perceived developmental task progression during adolescence was influential, but the more recent developmental task progression during emerging adulthood was even more predictive for different leaving-home outcomes. The amounts of fathers’ and mothers’ support during adolescence were found to be important predictors of the timing of leaving home.
Viscous constitutive relations of solid‐liquid composites in terms of grain boundary contiguity: 1. Grain boundary diffusion control model
Authors: Takei Yasuko , Holtzman Benjamin K.
Published: June 2009

Viscous constitutive relations of partially molten rocks deforming in the regime of grain boundary (GB) diffusion creep are derived theoretically on the basis of microstructural processes at the grain scale. The viscous constitutive relation developed in this study is based on contiguity as an internal state variable, which enables us to take into account the detailed effects of grain‐scale melt distribution observed in experiments. Compared to the elasticities derived previously for the same microstructural model, the viscosities are much more sensitive to the presence of melt and variations in contiguity. As explored in this series of three companion papers, this “contiguity” model predicts that a very small amount of melt (ϕ < 0.01) significantly reduces the bulk and shear viscosities. Furthermore, a large anisotropy in viscosity is produced by anisotropy in contiguity, which occurs in deforming partially molten rocks. These results have important implications for deformation and melt extraction at small melt fractions, as well as for shear‐induced melt segregation. The viscous and elastic constitutive relations derived in terms of contiguity bridge microscopic grain‐scale and macroscopic continuum properties. These constitutive relations are essential for investigating melt migration dynamics in a forward sense on the basis of the basic equations of two‐phase dynamics and in an inverse sense on the basis of seismological observations.
Seeking phyllosilicates in thermal infrared data: A laboratory and Martian data case study
Authors: McDowell Meryl L. , Hamilton Victoria E.
Published: June 2009

Previous analyses of Thermal Emission Spectrometer (TES) data produce results that could suggest a widespread distribution of phyllosilicate minerals over the surface of Mars, whereas studies of visible to near‐infrared (VNIR) data indicate a more limited distribution. We use VNIR detections of phyllosilicates in the vicinity of the Nili Fossae to determine the spectral characteristics of phyllosilicate‐bearing material in the thermal infrared (TIR). By investigating areas of VNIR phyllosilicate detection in more detail, we find that the phyllosilicate‐bearing material corresponds to spectral variation in Thermal Emission Imaging System decorrelation‐stretched TIR images and differences in infrared spectral shape that are consistent with, but not uniquely attributable to, mixtures of phyllosilicates and basalt. Phyllosilicate phases are modeled from TES data at abundances that average 5% over the region and at abundances near the 10–15% detection limit in our specific regions of interest. Deconvolution of numerical mixtures of phyllosilicate and basalt spectra indicates that these low abundances of phyllosilicates likely are not influenced by uncertainties greater than the 10–15% uncertainty of the method. TES spectra and modeled abundances vary between the phyllosilicate‐bearing material and the surrounding region, but this difference in composition cannot be attributed solely to the presence of phyllosilicates. We believe the inconsistencies in phyllosilicate occurrence between TES and VNIR analyses may be explained by the inclusion of phyllosilicates in the models of TES data as substitutes for poorly crystalline phases (e.g., allophane) not currently available in public infrared spectral libraries.
Lithospheric controls on melt production during continental breakup at slow rates of extension: Application to the North Atlantic
Authors: Armitage J. J. , Henstock T. J. , Minshull T. A. , Hopper J. R.
Published: June 2009

Rifted margins form from extension and breakup of the continental lithosphere. If this extension is coeval with a region of hotter lithosphere, then it is generally assumed that a volcanic margin would follow. Here we present the results of numerical simulations of rift margin evolution by extending continental lithosphere above a thermal anomaly. We find that unless the lithosphere is thinned prior to the arrival of the thermal anomaly or half spreading rates are more than ∼50 mm a−1, the lithosphere acts as a lid to the hot material. The thermal anomaly cools significantly by conduction before having an effect on decompression melt production. If the lithosphere is thinned by the formation of extensional basins then the thermal anomaly advects into the thinned region and leads to enhanced decompression melting. In the North Atlantic a series of extensional basins off the coast of northwest Europe and Greenland provide the required thinning. This observation suggests that volcanic margins that show slow rates of extension only occur where there is the combination of a thermal anomaly and previous regional thinning of the lithosphere.
The Protective Effect of Early Hypothermia on PTEN Phosphorylation Correlates with Free Radical Inhibition in Rat Stroke
Authors: Lee Sang Mi , Zhao Heng , Maier Carolina M , Steinberg Gary K
Published: June 2009

We recently showed that intraischemic moderate hypothermia (30°C) reduces ischemic damage through the Akt pathway after permanent distal middle cerebral artery occlusion in rats. The only Akt pathway component preserved by hypothermia is phosphorylated phosphatase and tensin homolog deleted on chromosome 10 (p-PTEN), which suggests that p-PTEN may have a central role in neuroprotection. Reactive oxygen species (ROS) are critically involved in mediating ischemic damage after stroke by interacting with signaling molecules, including Akt, PTEN, and δ-protein kinase C (PKC). We investigated the protective mechanisms of moderate hypothermia on these signaling proteins after transient focal ischemia in rats. Early moderate hypothermia (3h) was administered 15 mins before reperfusion, and delayed moderate hypothermia (3h) was applied 15 mins after reperfusion. Our results indicate that early hypothermia reduced infarction, whereas delayed hypothermia did not. However, both early and delayed hypothermia maintained levels of Mn-SOD (superoxide dismutase) and phosphorylated Akt and blocked δ-PKC cleavage, suggesting that these factors may not be critical to the protection of hypothermia. Nevertheless, early hypothermia preserved p-PTEN levels after reperfusion, whereas delayed hypothermia did not. Furthermore, ROS inhibition maintained levels of p-PTEN after stroke. Together, these findings suggest that phosphorylation levels of PTEN are closely associated with the protective effect of early hypothermia against stroke.
Rosiglitazone Alone Or in Combination with Tissue Plasminogen Activator Improves Ischemic Brain Injury in an Embolic Model in Rats
Authors: Wang Chen Xu , Ding Xiuqing , Noor Raza , Pegg Christina , He Chunyan , Shuaib Ashfaq
Published: June 2009

In this study, we examined whether rosiglitazone, a peroxisome proliferator-activated receptor gamma (PPAR γ) agonist, is neuroprotective in focal ischemic brain injury, and whether rosiglitazone can enhance the protective action of tissue plasminogen activator (tPA), an agent used clinically for thrombolytic therapy. Rats were subjected to ischemic brain injury by embolizing preformed clots into the middle cerebral artery (MCA). Treatment with rosiglitazone reduced infarction and improved functional recovery; it also enhanced the neuroprotective action of tPA and lengthened the time window for initiating tPA treatment. Occlusion of MCA resulted in a loss of collagen type IV, a major structural protein of the microvascular basal lamina, and tPA treatment worsened this loss. Rosiglitazone treatment prevented the reduction of collagen type IV in the ischemic injured brain by inhibiting the activation of matrix metallopeptidase-9 (MMP-9). In addition, rosiglitazone treatment reduced inflammatory reactions in the ischemic injured brain. Rosiglitazone either alone or in combination with tPA is an effective agent in the reduction of ischemic brain injury. The reduction of microvascular damage and inflammation contributes to the beneficial actions of rosiglitazone.
Electron temperature control by an external magnetic field in solenoidal inductive discharge
Authors: Lee Min-Hyong , Ku Ju-Hwan , Hwang Kwang-Tae , Chung Chin-Wook
Published: June 2009

Electron temperature control is performed by controlling the external magnetic field strength in a solenoidal inductive discharge. As the magnetic field strength increases, the electron temperature of the plasma bulk decreases. The temperature at the discharge center falls from 3.1 to 1.5 eV when a 52 G dc magnetic field is applied. This decrease in the temperature is accompanied by a decrease in the plasma density. The change in temperature by the magnetic field is caused by both the electron confinement and the restriction of electron transport by the magnetic field in solenoidal inductive discharge.
On the eigenvalues of the twisted Dirac operator
Authors: Jardim Marcos , Leão Rafael F.
Published: June 2009

Given a compact Riemannian spin manifold whose untwisted Dirac operator has trivial kernel, we find a family of connections ∇At for t∊[0,1] on a trivial vector bundle of rank no larger than dim M+1, such that the first eigenvalue of the twisted Dirac operator DAt is nonzero for t≠1 and vanishes for t=1. However, if one restricts the class of twisting connections considered, then nonzero lower bounds do exist. We illustrate this fact by establishing a nonzero lower bound for the Dirac operator twisted by Hermitian–Einstein connections over Riemann surfaces.
He ion irradiation damage in Al∕Nb multilayers
Authors: Li Nan , Martin M. S. , Anderoglu O. , Misra A. , Shao L. , Wang H. , Zhang X.
Published: June 2009

We investigate the evolution of microstructure and mechanical properties of sputter-deposited Al∕Nb multilayers with miscible fcc/bcc type interface and individual layer thickness, h, of 1–200nm, subjected to helium ion irradiations: 100keV He+ ions and a fluence of 6×1016∕cm2. Helium bubbles, 1–2nm in diameter, are observed. When h is greater than 25nm, hardnesses of irradiated multilayers barely change, whereas radiation hardening is more significant at smaller h. Transmission electron microscopy and scanning transmission electron microscopy studies reveal the formation of a thin layer of Nb3Al intermetallic phase along the Al∕Nb interface as a consequence of radiation induced intermixing. The dependence of radiation hardening on h is interpreted by using a composite model considering the formation of the hard Nb3Al intermetallic layer.
Richtmyer–Meshkov instability of a stratified fluid in transverse magnetic field
Authors: Cao Jintao , Wu Zhengwei , Ren Haijun , Li Ding
Published: June 2009

In the present work, the Richtmyer–Meshkov instability is examined in an N-layer stratified fluid which is impulsively accelerated and immersed in a homogeneous transverse magnetic field. By solving the initial value problem and the second-order linear differential perturbation equation, the expressions of interface amplitudes are analytically obtained. Two special cases N=2 and N=3 are discussed, and it is found that the Richtmyer–Meshkov instability is suppressed by the transverse magnetic field. It is also shown for the N=3 case, when a transverse magnetic field is present, that the interfaces oscillate with a high frequency and the oscillations repeat themselves periodically with a low frequency.
On the accuracy of thermionic electron emission models. I. Electron detachment from SF6−
Authors: Troe Jürgen , Miller Thomas M. , Viggiano Albert A.
Published: June 2009

Detailed statistical rate calculations combined with electron capture theory and kinetic modeling for the electron attachment to SF6 and detachment from SF6− [Troe et al., J. Chem. Phys. 127, 244303 (2007)] are used to test thermionic electron emission models. A new method to calculate the specific detachment rate constants kdet(E) and the electron energy distributions f(E,ε) as functions of the total energy E of the anion and the energy ε of the emitted electrons is presented, which is computationally simple but neglects fine structures in the detailed kdet(E). Reduced electron energy distributions f(E,ε∕⟨ε⟩) were found to be of the form (ε∕⟨ε⟩)nexp(−ε∕⟨ε⟩) with n≈0.15, whose shape corresponds to thermal distributions only to a limited extent. In contrast, the average energies ⟨ε(E)⟩ can be roughly estimated within thermionic emission and finite heat bath concepts. An effective temperature Td(E) is determined from the relation E−EA=⟨ESF6(Td)⟩+kTd, where ⟨ESF6(Td)⟩ denotes the thermal internal energy of the detachment product SF6 at the temperature Td and EA is the electron affinity of SF6. The average electron energy is then approximately given by ⟨ε(E)⟩=kTd(E), but dynamical details of the process are not accounted for by this approach. Simplified representations of kdet(E) in terms of Td(E) from the literature are shown to lead to only semiquantitative agreement with the equally simple but more accurate calculations presented here. An effective “isokinetic” electron emission temperature Te(E) does not appear to be useful for the electron detachment system considered because it neither provides advantages over a representation of kdet(E) as a function of Td(E), nor are recommended relations between Te(E) and Td(E) of sufficient accuracy.
Analysis of hopping conduction in semiconducting and metallic carbon nanotube devices
Authors: Perello David J. , Yu Woo Jong , Bae Dong Jae , Chae Seung Jin , Kim M. J. , Lee Young Hee , Yun Minhee
Published: June 2009

Single-walled carbon nanotube field-effect transistors were irradiated with 20 keV electrons using an e-beam lithography exposure method. Analysis of conduction data in the temperature range from 25 to 300 K indicated the creation of insulating regions containing traps along the nanotube channel. Further analysis of semiconducting and metallic nanotube devices shows dramatic differences in the effect of the electron exposure on the hopping defect barrier heights. Barriers for metallic nanotubes saturate at significantly larger values than semiconducting nanotubes due to shorter localization lengths. The limited and near constant density of states at the Fermi level induces a larger hopping length to localization length ratio, further limiting current and increasing measured trap heights. Poole–Frenkel hopping with an adjustment for electron localization is utilized to explain the inconsistencies. n-type and p-type barriers in the nanotube devices displayed exponential dependence on applied gate voltage bias, with the peak barrier height in the metallic device defining a switch of majority carrier.
Comment on “Dynamic aspects of the liquid-liquid phase transformation in silicon” [J. Chem. Phys. 129, 104503 (2008)]
Authors: Yannopoulos S. N.
Published: June 2009

Recently, Jakse and Pasturel [J. Chem. Phys.129, 104503 (2008)] using first principles molecular dynamics simulations reported evidence for a fragile-to-strong transition in supercooled liquid Si. This conclusion was based on the presence (absence) of a Boson peak in the low-density, strong liquid (high-density, fragile liquid) phase. Based on existing experimental data it is pointed out that (i) the assignment of the Boson peak in the above reference is erroneous and (ii) the Boson peak strength is not generally useful for determining the strong or fragile character of a supercooled liquid. Therefore, the inference that liquid-liquid phase transition in supercooled liquid Si is a fragile-to-strong transition is unjustifiable.
Variable Lieb–Oxford bound satisfaction in a generalized gradient exchange-correlation functional
Authors: Vela A. , Medel V. , Trickey S. B.
Published: June 2009

We propose a different way to satisfy both gradient expansion limiting behavior and the Lieb–Oxford bound in a generalized gradient approximation exchange functional by extension of the Perdew–Burke–Ernzerhof (PBE) form. Motivation includes early and recent exploration of modified values for the gradient expansion coefficient in the PBE exchange-correlation functional (cf. the PBEsol functional) and earlier experience with a numerical cutoff for large-s (s∝|∇n|/n4/3) in a version of the deMon molecular code. For either the original PBE or the PBEsol choice of the gradient coefficient, we find improved performance from using an s-dependent (spatially varying) satisfaction of the Lieb–Oxford bound which quenches to uniform electron gas behavior at large s. The mean absolute deviations (MADs) in atomization energies for a widely used test set of 20 small molecules are reduced by about 22% relative to PBE and PBEsol. For these small molecules, the bond length MADs are essentially unchanged.
Laser patterning of diamond. Part I. Characterization of surface morphology
Authors: Smedley John , Bohon Jen , Wu Qiong , Rao Triveni
Published: June 2009

As the use of diamond as a material for electronic and research applications increases, methods of patterning diamond will be required. In this work, single- and polycrystalline synthetic diamond samples were exposed to laser beams of different energies, wavelengths, and pulse durations. The effects of this exposure were characterized using optical microscopy, scanning electron microscopy, and atomic force microscopy. The threshold ablation energy density for 266 nm radiation with ∼30 ps pulse duration was measured to be ∼14 J/cm2. The threshold for ∼10 ns pulses at the same wavelength was similar, but the ablated area displayed larger surface damage. The surface damage and the threshold energy increase significantly for 532 and 1064 nm radiations. Ablation performed using 213 nm radiation produced the most uniform surface. Changes in the ablated surface are presented in detail.
Laser patterning of diamond. Part II. Surface nondiamond carbon formation and its removal
Authors: Smedley John , Jaye Cherno , Bohon Jen , Rao Triveni , Fischer Daniel A.
Published: June 2009

As diamond becomes more prevalent for electronic and research applications, methods of patterning diamond will be required. One such method, laser ablation, has been investigated in a related work. We report on the formation of surface nondiamond carbon during laser ablation of both polycrystalline and single-crystal synthetic diamonds. Near edge x-ray absorption fine structure spectroscopy was used to confirm that the nondiamond carbon layer formed during the ablation was amorphous, and Fourier transform infrared absorption spectroscopy (FTIR) was used to estimate the thickness of this layer to be ∼60 nm. Ozone cleaning was used to remove the nondiamond carbon layer.
Theoretical study of solvent effects on the coil-globule transition
Authors: Polson James M. , Opps Sheldon B. , Abou Risk Nicholas
Published: June 2009

The coil-globule transition of a polymer in a solvent has been studied using Monte Carlo simulations of a single chain subject to intramolecular interactions as well as a solvent-mediated effective potential. This solvation potential was calculated using several different theoretical approaches for two simple polymer/solvent models, each employing hard-sphere chains and hard-sphere solvent particles as well as attractive square-well potentials between some interaction sites. For each model, collapse is driven by variation in a parameter which changes the energy mismatch between monomers and solvent particles. The solvation potentials were calculated using two fundamentally different methodologies, each designed to predict the conformational behavior of polymers in solution: (1) the polymer reference interaction site model (PRISM) theory and (2) a many-body solvation potential (MBSP) based on scaled particle theory introduced by Grayce [J. Chem. Phys. 106, 5171 (1997)]. For the PRISM calculations, two well-studied solvation monomer-monomer pair potentials were employed, each distinguished by the closure relation used in its derivation: (i) a hypernetted-chain (HNC)-type potential and (ii) a Percus–Yevick (PY)-type potential. The theoretical predictions were each compared to results obtained from explicit-solvent discontinuous molecular dynamics simulations on the same polymer/solvent model systems [J. Chem. Phys. 125, 194904 (2006)]. In each case, the variation in the coil-globule transition properties with solvent density is mostly qualitatively correct, though the quantitative agreement between the theory and prediction is typically poor. The HNC-type potential yields results that are more qualitatively consistent with simulation. The conformational behavior of the polymer upon collapse predicted by the MBSP approach is quantitatively correct for low and moderate solvent densities but is increasingly less accurate for higher densities. At high solvent densities, the PRISM-HNC and MBSP approaches tend to overestimate, while the PRISM-PY approach underestimates the tendency of the solvent to drive polymer collapse.
Optical studies of type-I GaAs1−xSbx/GaAs multiple quantum well structures
Authors: Sitarek P. , Hsu H. P. , Huang Y. S. , Lin J. M. , Lin H. H. , Tiong K. K.
Published: June 2009

We present photoreflectance (PR) and surface photovoltage spectroscopy (SPS) studies of GaAs1−xSbx/GaAs multiple quantum well structures with fundamental transition close to 1.3 μm. These two optical diagnostic tools are powerful supplementary techniques in the investigations of complicated quantum systems. PR gives detailed information about the heavy-holes related transitions, while SPS contains additional information concerning light-holes related ones. The comparison of experimental data and theoretical analysis based on the envelope function approximation, including strain and exciton binding energy, allows us to identify the observed PR and SPS features. The results point to the existence of weak type-I band alignment in samples being studied, and the Sb content dependent of conduction band offset is found to agree well with that reported by Wang et al. [Phys. Rev. B 70, 195339 (2004)].
Theoretical study of subwavelength imaging by acoustic metamaterial slabs
Authors: Deng Ke , Ding Yiqun , He Zhaojian , Zhao Heping , Shi Jing , Liu Zhengyou
Published: June 2009

We investigate theoretically subwavelength imaging by acoustic metamaterial slabs immersed in the liquid matrix. A near-field subwavelength image formed by evanescent waves is achieved by a designed metamaterial slab with negative mass density and positive modulus. A subwavelength real image is achieved by a designed metamaterial slab with simultaneously negative mass density and modulus. These results are expected to shed some light on designing novel devices of acoustic metamaterials.
Direct observation of localized conduction pathways in photocross-linkable polymer memory
Authors: Kwan Wei Lek , Lei Bao , Shao Yue , Prikhodko Sergey V. , Bodzin Noah , Yang Yang
Published: June 2009

Resistive switching in photocross-linkable polymer memory devices was found to occur in localized areas of the device. In order to elucidate the reason behind the switching, we used focused ion-beam to prepare a cross-section of the device. It was found that after the device was switched to the high conductive state, in certain parts of the device, the electrodes were only about 5 nm apart. This was probably caused by a combination of high electric field and metal injection into the polymer film. Gold injection into the polymer film by locally enhanced electric field was confirmed by transmission electron microscope-energy dispersive x-ray analysis. This model was in agreement with both the temperature dependent and transient behavior of our device. We conclude that the non-uniformities at the nanoscale interface of the electrode dominated the device characteristics while the polymer played only a secondary role.
General anticipating response in coupled dynamical systems
Authors: Yan Hua , Wei Ping , Xiao Xian-Ci
Published: June 2009

We suggest a general anticipating response scheme from which a large class of different drive-response systems can be constructed by choosing a function to be determined. A specific case of the general scheme is studied in detail. This specific scheme, which is called the accelerative anticipating response scheme, makes the response system evolve along the same trajectory as the driver but with a faster speed. This counterintuitive phenomenon is proved to be robust against the disturbances of the driving term and the driving signal as well as parameter mismatches. So it may have potential applications in the environment where disturbances and parameter mismatches are unavoidable.
Krook model for nonthermal electron energy transport. III. Spherical configurations
Authors: Colombant Denis , Manheimer Wallace
Published: June 2009

In earlier works the Krook model for nonlocal electron energy transport in laser produced plasmas was examined. This paper extends the earlier work by treating spherical configurations, specifically laser driven implosions. Additions to the theory due to spherical geometry are worked out. As in the planar case, the nonlocal effects manifest themselves both as flux limitation and preheat. Nonlocal transport does have an effect on the fusion gain of laser pellet implosions.
Period-two discharge characteristics in argon atmospheric dielectric-barrier discharges
Authors: Wang Yanhui , Shi Hong , Sun Jizhong , Wang Dezhen
Published: June 2009

Period multiplication and chaos behaviors in atmospheric glow discharges are important to understand atmospheric glow plasma stability and to optimize its applications. In this paper, we study the period-two discharge characteristics in argon atmospheric dielectric-barrier discharges using a one-dimension fluid model. Under certain conditions, period-two discharges can occur at different excitation frequencies and exhibit different current and voltage behaviors. When the discharge current becomes highly symmetrical the period-two discharge can reach to a steady state, which sustains over a broad frequency range. At the sufficiently high excitation frequency, the period-two discharge in atmospheric argon shows noticeably different behaviors from the discharges generated at kilohertz frequency. The spatial characteristics of period-two discharge as well as the influence of driving frequency on period-two discharge behaviors are also investigated.
An inverse problem for a heat equation with piecewise-constant thermal conductivity
Authors: Hoang N. S. , Ramm A. G.
Published: June 2009

The governing equation is ut=(a(x)ux)x, 0≤x≤1, t>0, u(x,0)=0, u(0,t)=0, a(1)u′(1,t)=f(t). The extra data are u(1,t)=g(t). It is assumed that a(x) is a piecewise-constant function and f≢0. It is proved that the function a(x) is uniquely defined by the above data. No restrictions on the number of discontinuity points of a(x) and on their locations are made. The number of discontinuity points is finite, but this number can be arbitrarily large. If a(x)∊C2[0,1], then a uniqueness theorem has been established earlier for multidimensional problem, x∊Rn,n>1 [see A. G. Ramm, Multidimensional inverse problems and completeness of the products of solutions to PDE, J. Math. Anal. Appl., 134, 211 (1988)] for the stationary problem with infinitely many boundary data. The novel point in this work is the treatment of the discontinuous piecewise-constant function a(x) and the proof of Property C for a pair of the operators {ℓ1,ℓ2}, where ℓj≔−(d2/dx2)+k2qj2(x), j=1,2, and qj2(x)>0 are piecewise-constant functions, and for the pair {L1,L2}, where Lju≔−[aj(x)u′(x)]′+λu, j=1,2, and aj(x)>0 are piecewise-constant functions. Property C stands for completeness of the set of products of solutions of homogeneous differential equations [see A. G. Ramm, Inverse Problems (Springer, New York, 2005)].
ZnO solid-state dye sensitized solar cells using composite electrolyte of poly(3-hexylthiophene-2,5-diyl) and carbon nanotubes
Authors: Rani Seema , Mehra R. M.
Published: June 2009

Solid-state dye sensitized solar cells (DSSCs) could become alternative to liquid electrolyte-based cells which suffer from several problems such as leakage, encapsulation, and cell interconnections within the module. In this paper we focus on ZnO solid-state DSSCs employing thiophene-based polymer poly(3-hexylthiophene-2,5-diyl) (P3HT) as hole conducting agent. The effect of the addition of multiwalled carbon nanotubes (MWCNTs) in P3HT on the solar cell parameters was investigated. Current-voltage (I-V) characteristics of the different cells were obtained having different wt % of MWCNTs. Using the I-V characteristics and single diode model for the solar cell, various parameters such as the photocurrent, the saturation current of the diode, the series resistance, the shunt resistance, and the ideality factor were determined. The use of MWCNTs with polymer P3HT increased the photovoltaic performance of the solar cells. Highest device performance was achieved with 0.8 wt % of MWCNTs in P3HT. The role of MWCNTs for efficient hole transfer was discussed in terms of series and shunt resistances.
Revisiting the two first instabilities of the flow in an annular rotor-stator cavity
Authors: Poncet Sébastien , Serre Éric , Le Gal Patrice
Published: June 2009

The stability of the flow enclosed between a stationary and a rotating disk with a central hub is revisited by experimental visualizations and direct numerical simulations in the case of unmerged boundary layers. The first instability appears as circular rolls, denoted by CRs (type 2 instability), which propagate along the stator before vanishing in the vicinity of the hub. The calculations highlight the convective nature of these rolls, which is in agreement with previous experimental results (P. Gauthier, P. Gondret, and M. Rabaud, J. Fluid Mech. 386, 105 (1999)). It proves in particular that the CR instability observed in the experiment under permanent conditions is noise sustained. Above a second threshold, spiral rolls, denoted SR1 (type 1 instability), appear at the periphery of the cavity and can coexist with the circular rolls. The DNS shows that they appear through a supercritical Hopf bifurcation. The SR1 patterns appear to be very close to those emitted by the corner vortices obtained by Lopez and Weidman [J. Fluid Mech. 326, 373 (1996)] during the spin-down of a rotating disk in a fixed cylinder.
Categorization of resistive switching of metal-Pr0.7Ca0.3MnO3-metal devices
Authors: Liao Z. L. , Wang Z. Z. , Meng Y. , Liu Z. Y. , Gao P. , Gang J. L. , Zhao H. W. , Liang X. J. , Bai X. D. , Chen D. M.
Published: June 2009

Resistive switching (RS) characteristics of a Pr0.7Ca0.3MnO3 (PCMO) film sandwiched between a Pt bottom electrode and top electrodes (TE) made of various metals are found to belong to two categories. Devices with TE made of Al, Ti, and Ta exhibit a large I-V hysteresis loop and bipolar RS, but those with TE made of Pt, Ag, Au, and Cu do not. Transmission electron microscopy reveals that a thin metal-oxide layer formed at the interface between the former group of TE and PCMO, but not for the latter group of TE. Analysis shows that the categorization depends on the Gibbs free energy of oxidation of the TEs with respect to that of PCMO.
An air-slotted nanoresonator relying on coupled high Q small V Fabry–Perot nanocavities
Authors: Foubert Kevin , Lalouat Loïc , Cluzel Benoît , Picard Emmanuel , Peyrade David , de Fornel Frédérique , Hadji Emmanuel
Published: June 2009

We study here the lateral evanescent coupling between photonic crystals cavities. The structure consists in two identical monomode Fabry–Perot nanocavities, integrated on silicon-on-insulator slot-waveguides (WG). Spectral and optical near field measurements were led and supported quantitatively by three dimensional simulations. It appears that this system produces a bimodal response: two resonances corresponding, respectively, to an even and odd mode. Particularly, the even case exhibits a field localization in the air slot inferior to λair/10. We demonstrate that merging a slotted WG structure with state-of-the-art nanocavities is a significant step toward an efficient air-slotted resonator.
Magnetic-island-induced ion temperature gradient mode
Authors: Wang Z. X. , Li J. Q. , Kishimoto Y. , Dong J. Q.
Published: June 2009

Characteristics of ion temperature gradient (ITG) instability in the presence of a magnetic island are investigated numerically using a gyrofluid model. It is shown that when the magnetic island is wide enough to produce a broad distribution of rational surfaces near the O-point region, the ITG perturbations at these rational surfaces form a radially global-type eigenmode with a fast growth rate, which is referred to as the magnetic-island-induced ITG mode. Moreover, the magnetic island also causes both radial and poloidal mode couplings, which play a stabilizing role.
Oxidoreductase activity of oligosaccharyltransferase subunits Ost3p and Ost6p defines site-specific glycosylation efficiency
Authors: Schulz Benjamin L. , Stirnimann Christian U. , Grimshaw John P. A. , Brozzo Maurice S. , Fritsch Fabienne , Mohorko Elisabeth , Capitani Guido , Glockshuber Rudi , Grütter Markus G. , Aebi Markus
Published: June 2009

Asparagine-linked glycosylation is a common posttranslational modification of diverse secretory and membrane proteins in eukaryotes, where it is catalyzed by the multiprotein complex oligosaccharyltransferase. The functions of the protein subunits of oligoasccharyltransferase, apart from the catalytic Stt3p, are ill defined. Here we describe functional and structural investigations of the Ost3/6p components of the yeast enzyme. Genetic, biochemical and structural analyses of the lumenal domain of Ost6p revealed oxidoreductase activity mediated by a thioredoxin-like fold with a distinctive active-site loop that changed conformation with redox state. We found that mutation of the active-site cysteine residues of Ost6p and its paralogue Ost3p affected the glycosylation efficiency of a subset of glycosylation sites. Our results show that eukaryotic oligosaccharyltransferase is a multifunctional enzyme that acts at the crossroads of protein modification and protein folding.
Detection and differentiation of normal, cancerous, and metastatic cells using nanoparticle-polymer sensor arrays
Authors: Bajaj Avinash , Miranda Oscar R. , Kim Ik-Bum , Phillips Ronnie L. , Jerry D. Joseph , Bunz Uwe H. F. , Rotello Vincent M.
Published: June 2009

Rapid and effective differentiation between normal and cancer cells is an important challenge for the diagnosis and treatment of tumors. Here, we describe an array-based system for identification of normal and cancer cells based on a “chemical nose/tongue” approach that exploits subtle changes in the physicochemical nature of different cell surfaces. Their differential interactions with functionalized nanoparticles are transduced through displacement of a multivalent polymer fluorophore that is quenched when bound to the particle and fluorescent after release. Using this sensing strategy we can rapidly (minutes/seconds) and effectively distinguish (
i
) different cell types; (
ii
) normal, cancerous and metastatic human breast cells; and (
iii
)
isogenic
normal, cancerous and metastatic murine epithelial cell lines.