bluuebunny/crossref_metadata_2025 huggingface dataset:
Rights of Man
Authors: Paine Thomas
Published: December 2012

A major actor in the American Revolution, English intellectual Thomas Paine (1737–1809) is remembered especially for his pamphlet Common Sense (1776; also reissued in this series), which advocates America's independence from Great Britain. An immediate best-seller, it sold over 100,000 copies in three months. Paine was a dedicated reformer who also lent his support to the French Revolution. First published in 1791, this book was sparked by the publication of Edmund Burke's Reflections on the Revolution in France (1790), a direct condemnation of the French uprising; and the fourth edition of this remarkable contribution to political philosophy is reissued here. In a passionate rebuttal of Burke's position, Paine argues that revolution is legitimate against a government that fails to protect its people and their essential rights. Extremely influential in its own day, this book develops a critique of authoritarian governments that remains relevant today.
ON -LIKE RADICALS OF RINGS
Authors: FRANCE-JACKSON H. , KHULAN T. , TUMURBAT S.
Published: December 2012

Let$\alpha $be any radical of associative rings. A radical$\gamma $is called$\alpha $-like if, for every$\alpha $-semisimple ring$A$, the polynomial ring$A[x] $is$\gamma $-semisimple. In this paper we describe properties of$\alpha $-like radicals and show how they can be used to solve some open problems in radical theory.
WIENER INDEX AND TRACEABLE GRAPHS
Authors: YANG LIHUI
Published: December 2012

In this short paper, we show that, with three exceptions, if the Wiener index of a connected graph of order $n$ is at most $(n+ 5)(n- 2)/ 2$, then it is traceable.
POROSITY OF CERTAIN SUBSETS OF LEBESGUE SPACES ON LOCALLY COMPACT GROUPS
Authors: AKBARBAGLU I. , MAGHSOUDI S.
Published: December 2012

Let $G$ be a locally compact group. In this paper, we show that if $G$ is a nondiscrete locally compact group, $p\in (0, 1)$ and $q\in (0, + \infty ] $, then $\{ (f, g)\in {L}^{p} (G)\times {L}^{q} (G): f\ast g\text{ is finite } \lambda \text{-a.e.} \} $ is a set of first category in ${L}^{p} (G)\times {L}^{q} (G)$. We also show that if $G$ is a nondiscrete locally compact group and $p, q, r\in [1, + \infty ] $ such that $1/ p+ 1/ q\gt 1+ 1/ r$, then $\{ (f, g)\in {L}^{p} (G)\times {L}^{q} (G): f\ast g\in {L}^{r} (G)\} $, is a set of first category in ${L}^{p} (G)\times {L}^{q} (G)$. Consequently, for $p, q\in [1+ \infty )$ and $r\in [1, + \infty ] $ with $1/ p+ 1/ q\gt 1+ 1/ r$, $G$ is discrete if and only if ${L}^{p} (G)\ast {L}^{q} (G)\subseteq {L}^{r} (G)$; this answers a question raised by Saeki [‘The ${L}^{p} $-conjecture and Young’s inequality’, Illinois J. Math. 34 (1990), 615–627].
PHOTOSYNTHETIC ACTIVITY AND EARLY GROWTH OF FOUR CACAO GENOTYPES AS INFLUENCED BY DIFFERENT SHADE REGIMES UNDER WEST AFRICAN DRY AND WET SEASON CONDITIONS
Authors: ACHEAMPONG K. , HADLEY P. , DAYMOND A. J.
Published: December 2012

The physiological performance of four cacao clones was examined under three artificial shade regimes over the course of a year in Ghana. Plants under light shade had significantly higher photosynthetic rates in the rainy seasons whereas in the dry season there was a trend of higher photosynthetic rates under heavy shade. The results imply that during the wet seasons light was the main limiting factor to photosynthesis whereas in the dry season vapour pressure deficit was the major factor limiting photosynthesis through stomatal regulation. Leaf area was generally lower under heavier shade but the difference between shade treatments varied between clones. Such differences in leaf area allocation appeared to underlie genotypic differences in final biomass production in response to shade. The results suggest that shade for young cacao should be provided based on the current ambient environment and genotype.
EDITORIAL
Authors: Harris Dave
Published: December 2012

We are very sad to say goodbye to Dr Lindsay Innes, OBE, FRSE who is retiring from the post of Book Review Editor that he has held for 15 years. During that time, Lindsay has worked tirelessly to ensure that regular readers of Experimental Agriculture have always been able to find out what books they should be reading, and why, by consulting the Journal's concise, incisive reviews by renowned experts from a bewildering range of fields. Lindsay, whose career description reads like a summary of all the top jobs in International Agricultural Research, always knew the best person to ask to review a book and the result was that we got the best reviews. We will miss him but we thank him sincerely for his work for the journal and we wish Lindsay the best of luck for the future.
Effect of estradiol during culture of bovine oocyte–granulosa cell complexes on the mitochondrial DNA copies of oocytes and telomere length of granulosa cells
Authors: Endo M. , Kimura K. , Kuwayama T. , Monji Y. , Iwata H.
Published: December 2012

During the development of oocytes from early antral follicles (EAFs) to antral follicles (AFs), the mitochondrial DNA copy number (Mt DNA number) increases, and granulosa cells markedly proliferate. This study examined the effect of supplementation of culture medium with estradiol-17β (E2) on the in vitro growth of oocytes, and increases in the Mt DNA number, and telomere length during the in vitro culture of oocytes derived from EAFs (0.4–0.7 mm in diameter). The E2 supplementation improved antrum formation and the ratio of oocytes reaching the metaphase II (MII) stage, and there was a significant difference in these values between addition E2 concentrations of 10 μg/ml and 0.1 μg/ml. When the oocytes were cultured in the medium containing 10 μg/ml E2, the Mt DNA number determined by real-time polymerase chain reaction (PCR) significantly increased, and the ratio of the Mt DNA number at the end of culture to the Mt DNA number at the beginning of the culture was greatly different among cows, and could be predicted by the degree of the difference between the Mt DNA number of oocytes derived from EAFs and that of oocytes derived from AFs (3–6 mm in diameter). When oocytes were cultured for 16 days in a medium containing 10 μg/ml E2 or 0.1 μg/ml E2, the Mt DNA number of oocytes grown in vitro did not differ, but the telomere length of the granulosa cells was significantly greater in the 10 μg/ml E2 group than in the 0.1 μg/ml group. In conclusion, E2 supplementation in culture medium improved the growth of oocytes derived from EAFs, and a high E2 concentration increased the telomere length of the granulosa cells.
A SOBOLEV ALGEBRA OF VOLTERRA TYPE
Authors: GALÉ JOSÉ E. , SÁNCHEZ-LAJUSTICIA LUIS
Published: December 2012

We present a family of radical convolution Banach algebras on intervals (0,a] which are of Sobolev type; that is, they are defined in terms of derivatives. Among other properties, it is shown that all epimorphisms and derivations of such algebras are bounded. Also, we give examples of nontrivial concrete derivations.
Change in Women's Descriptive Representation and the Belief in Women's
Ability to Govern: A Virtuous Cycle
Authors: Alexander Amy C.
Published: December 2012

As a core principle of democratic theory, political scientists stress
the importance of more inclusive and diverse elected bodies (Mansbridge
1999; Phillips 1995; Pitkin 1967; Williams 1998; Young 2000). A large
portion of that literature discusses the positive symbolic effects of
elected bodies when they come closer to mirroring the population from which
they are drawn. For underrepresented groups, increases in their descriptive
representation symbolize a more open political arena. This improves the
group's political participation as well as beliefs about the group's role in
politics.
Representation and Inclusion
Authors: Phillips Anne
Published: December 2012

In 1995, the fourth and most influential world conference on women
delivered the Beijing Declaration, calling for “women's empowerment and
their full participation on the basis of equality in all spheres of society,
including participation in the decision-making process and access to power.”
The idea that women needed not just the equal right to vote and participate
in politics, but “full participation on the basis of equality,” had been
gathering force for a number of years. Activists around the world had long
challenged the underrepresentation of women in legislatures and
decision-making assemblies. Political parties in the Scandinavian countries
had been experimenting with voluntary gender quotas from the early 1980s. In
the course of the 1990s, a number of countries, particularly in Latin
America, made it a legal or constitutional requirement that something had to
be done. Votes for women were the key demand at the end of the nineteenth
century; parity of representation was the new demand by the end of the
twentieth.
Gender, Race, Ethnicity, and Political Representation in the United
States
Authors: Minta Michael D.
Published: December 2012

In the Concept of Representation, Hanna
Pitkin (1967) argues that legislators should be judged by their
actions—substantive representation—and not just their closeness in
characteristics to their constituents—descriptive representation. Pitkin's
theoretical framework is the standard that political representation scholars
use when evaluating whether the presence of women or racial and ethnic
minorities in legislatures results in greater responsiveness to female or
minority interests. Do female legislators better represent the interests of
women in U.S. congressional committee hearings on domestic violence than
male legislators? Are minority legislators more active in advocating for
minority interests than white legislators in hearings relating to racial
profiling? Although Pitkin is skeptical that descriptive representatives
alone improve legislators' responsiveness to the interests of constituents
that they descriptively represent, extensive normative and empirical
analyses focusing on race and gender have demonstrated that it is not a
question of whether descriptive representation matters, but rather when and
how it matters to improving substantive representation (see, for example,
Bratton 2005; Canon 1999; Casellas 2011; Gamble 2007; Gay 2001; Grose 2011;
Haynie 2001; Lublin 1997; Mansbridge 1999; Tate 2003; Thomas 1994; Whitby
1997).
Planar inverted-F antenna with J-shaped slot and parasitic element for ultra-wide band application
Authors: Ibnyaich Saida , Ghammaz Abdelilah , Hassani Moha M'rabet
Published: December 2012

This paper presents a planar inverted-F antenna (PIFA) for ultra-wide band (UWB) communication, which is printed on a dielectric substrate of FR4-epoxy with 4.4 relative permittivity (ɛr), 2 mm thickness. This antenna is designed to be used in a 2.9–10.7 GHz frequency band, and a very wide bandwidth is realized by the addition of a parasitic element and a J-shaped slot to the PIFA. The effects of varying the parameters of the antenna on the performance have been investigated.
The National Longitudinal Study of Adolescent Health (Add Health) Sibling Pairs Data
Authors: Harris Kathleen Mullan , Halpern Carolyn Tucker , Haberstick Brett C. , Smolen Andrew
Published: December 2012

This article describes the design and phenotype and genotype data available for sibling pairs with varying genetic relatedness in the National Longitudinal Study of Adolescent Health (Add Health). Add Health is a nationally representative longitudinal study of over 20,000 adolescents in the United States in 1994–1995 who have been followed for 15 years into adulthood. The Add Health design included oversamples of more than 3,000 pairs of individuals with varying genetic resemblance, ranging from monozygotic twins, dizygotic twins, full siblings, half siblings, and unrelated siblings who were raised in the same household. Add Health sibling pairs are therefore nationally representative and followed longitudinally from early adolescence into adulthood with four in-home interviews during the period 1994–2009. Add Health has collected rich longitudinal social, behavioral, environmental, and biological data, as well as buccal cell DNA from all sample members, including sibling pairs. Add Health has an enlightened dissemination policy and to date has released phenotype and genotype data to more than 10,000 researchers in the scientific community.
Inorganic and black carbon aerosols in the Los Angeles Basin during CalNex
Authors: Ensberg J. J. , Craven J. S. , Metcalf A. R. , Allan J. D. , Angevine W. M. , Bahreini R. , Brioude J. , Cai C. , Coe H. , de Gouw J. A. , Ellis R. A. , Flynn J. H. , Haman C. L. , Hayes P. L. , Jimenez J. L. , Lefer B. L. , Middlebrook A. M. , Murphy J. G. , Neuman J. A. , Nowak J. B. , Roberts J. M. , Stutz J. , Taylor J. W. , Veres P. R. , Walker J. M. , Seinfeld J. H.
Published: December 2012

We evaluate predictions from the Community Multiscale Air Quality (CMAQ version 4.7.1) model against a suite of airborne and ground‐based meteorological measurements, gas‐ and aerosol‐phase inorganic measurements, and black carbon (BC) measurements over Southern California during the CalNex field campaign in May/June 2010. Ground‐based measurements are from the CalNex Pasadena ground site, and airborne measurements took place onboard the Center for Interdisciplinary Remotely‐Piloted Aircraft Studies (CIRPAS) Navy Twin Otter and the NOAA WP‐3D aircraft. BC predictions are in general agreement with observations at the Pasadena ground site and onboard the WP‐3D, but are consistently overpredicted when compared to Twin Otter measurements. Adjustments to predicted inorganic mass concentrations, based on predicted aerosol size distributions and the AMS transmission efficiency, are shown to be significant. Owing to recent shipping emission reductions, the dominant source of sulfate in the L.A. Basin may now be long‐range transport. Sensitivity studies suggest that severely underestimated ammonia emissions, and not the exclusion of crustal species (Ca2 +, K+, and Mg2 +), are the single largest contributor to measurement/model disagreement in the eastern part of the L.A. Basin. Despite overstated NOx emissions, total nitrate concentrations are underpredicted, which suggests a missing source of HNO3 and/or overprediction of deposition rates. Adding gas‐phase NH3 measurements and size‐resolved measurements, up to 10 μm, of nitrate and various cations (e.g. Na+, Ca2 +, K+) to routine monitoring stations in the L.A. Basin would greatly facilitate interpreting day‐to‐day fluctuations in fine and coarse inorganic aerosol.
Assessing Post-Stroke Behavior in Mouse Models of Focal Ischemia
Authors: Balkaya Mustafa , Kröber Jan M , Rex Andre , Endres Matthias
Published: December 2012

Experimental treatment strategies and neuroprotective drugs that showed therapeutic promise in animal models of stroke have failed to produce beneficial effects in human stroke patients. The difficulty in translating preclinical findings to humans represents a major challenge in cerebrovascular research. The reasons behind this translational road block might be explained by a number of factors, including poor quality control in various stages of the research process, the validity of experimental stroke models, and differences in drug administration and pharmacokinetics. Another major difference between animal studies and clinical trials is the choice of end point or outcome measures. Here, we discuss the necessity of poststroke behavioral testing to bridge the gap between clinical and experimental end points. We review established sensory-motor tests for outcome determination after focal ischemia based on the published literature as well as our own personal experience. Selected tests are described in more detail and good laboratory practice standards for behavioral testing are discussed. This review is intended for stroke researchers planning to use behavioral testing in mice.
Extracellular Brain Ph with or without Hypoxia is a Marker of Profound Metabolic Derangement and Increased Mortality after Traumatic Brain Injury
Authors: Timofeev Ivan , Nortje Jurgens , Al-Rawi Pippa G , Hutchinson Peter JA , Gupta Arun K
Published: December 2012

Cerebral hypoxia and acidosis can follow traumatic brain injury (TBI) and are associated with increased mortality. This study aimed to evaluate a relationship between reduced pHbt and disturbances of cerebral metabolism. Prospective data from 56 patients with TBI, receiving microdialysis and Neurotrend monitoring, were analyzed. Four tissue states were defined based on pHbt and PbtO2: 1—low PbtO2/pHbt, 2—low pHbt/normal PbtO2, 3—normal pHbt/low PbtO2, and 4—normal pHbt/PbtO2). Microdialysis values were compared between the groups. The relationship between PbtO2 and lactate/pyruvate (LP) ratio was evaluated at different pHbt levels. Proportional contribution of each state was evaluated against mortality. As compared with the state 4, the state 3 was not different, the state 2 exhibited higher levels of lactate, LP, and glucose and the state 1—higher LP and reduced glucose ( P < 0.001). A significant negative correlation between LP and PbtO2 (rho = −0.159, P < 0.001) was stronger at low pHbt (rho = −0.201, P < 0.001) and nonsignificant at normal pHbt ( P = 0.993). The state 2 was a significant discriminator of mortality categories ( P = 0.031). Decreased pHbt is associated with impaired metabolism. Measuring pHbt with PbtO2 is a more robust way of detecting metabolic derangements.
Subfield-Specific Neurovascular Remodeling in the Entorhino-Hippocampal-Organotypic Slice Culture as a Response to Oxygen–Glucose Deprivation and Excitotoxic Cell Death
Authors: Chip Sophorn , Nitsch Cordula , Wellmann Sven , Kapfhammer Josef P
Published: December 2012

Transient ischemia causes delayed neurodegeneration in selective brain areas, particularly in the CA1 field of the hippocampus. This is accompanied by neurovascular impairment. It is unknown whether neurodegeneration is the cause or consequence of vascular changes. In an entorhino-hippocampal-organotypic slice culture system with well-preserved blood vessels, we studied the interplay between neurodegeneration and neurovasculature. Short-term oxygen and glucose deprivation (OGD) resulted in upregulation of hypoxic markers and with a delay of 24 to 48 hours in selective nerve cell death in CA1. In parallel, local vessel density decreased as detected by markers of endothelial cells and of the extracellular matrix. Claudin-5, a tight junction protein and marker of the blood–brain barrier was reduced. Preventing neuronal death with tetrodotoxin or 6-cyano-7-nitroquinoxaline-2,3-dione rescued blood vessels, suggesting that vessel loss is not due to OGD per se but a consequence of neuronal death. Induction of excitotoxic neuronal death with AMPA caused widespread neurodegeneration, but vessel reduction was confined to CA1. In dentate gyrus without neuronal loss, vessel density increased. We propose that neuronal stress and death influence maintenance, loss and remodeling of the neurovasculature and that the type of vascular response is in addition determined by local factors within the hippocampus.
Detection of Impaired Cerebral Autoregulation Improves by Increasing Arterial Blood Pressure Variability
Authors: Katsogridakis Emmanuel , Bush Glen , Fan Lingke , Birch Anthony A , Simpson David M , Allen Robert , Potter John F , Panerai Ronney B
Published: December 2012

Although the assessment of dynamic cerebral autoregulation (CA) based on measurements of spontaneous fluctuations in arterial blood pressure (ABP) and cerebral blood flow (CBF) is a convenient and much used method, there remains uncertainty about its reliability. We tested the effects of increasing ABP variability, provoked by a modification of the thigh cuff method, on the ability of the autoregulation index to discriminate between normal and impaired CA, using hypercapnia as a surrogate for dynamic CA impairment. In 30 healthy volunteers, ABP (Finapres) and CBF velocity (CBFV, transcranial Doppler) were recorded at rest and during 5% CO2 breathing, with and without pseudo-random sequence inflation and deflation of bilateral thigh cuffs. The application of thigh cuffs increased ABP and CBFV variabilities and was not associated with a distortion of the CBFV step response estimates for both normocapnic and hypercapnic conditions ( P = 0.59 and P = 0.96, respectively). Sensitivity and specificity of CA impairment detection were improved with the thigh cuff method, with the area under the receiver–operator curve increasing from 0.746 to 0.859 ( P = 0.031). We conclude that the new method is a safe, efficient, and appealing alternative to currently existing assessment methods for the investigation of the status of CA.
Exploring the structural determinants of selective phosphopeptide recognition using bivalent metal-coordination complexes
Authors: Kraskouskaya Dziyana , Drewry Joel A. , Duodu Eugenia , Burger Steven , Eaton James , Cisneros G. Andrés , Gunning Patrick T.
Published: December 2012

We demonstrate that Lewis acidic coordination complexes equipped with cationic binding groups might be best utilized as selective receptors for binding phosphopeptides with anionic side chain residues proximal to the phosphorylated residue.
Comparison of molecular dynamics methods and interatomic potentials for calculating the thermal conductivity of silicon
Authors: Howell P. C.
Published: December 2012

We compare the molecular dynamics Green–Kubo and direct methods for calculating thermal conductivity κ, using as a test case crystalline silicon at temperatures T in the range 500–1000 K (classical regime). We pay careful attention to the convergence with respect to simulation size and duration and to the procedures used to fit the simulation data. We show that in the Green–Kubo method the heat current autocorrelation function is characterized by three decay processes, of which the slowest lasts several tens of picoseconds so that convergence requires several tens of nanoseconds of data. Using the Stillinger–Weber potential we find excellent agreement between the two methods. We also use the direct method to calculate κ(T) for the Tersoff potential and find that the magnitude and the temperature-dependence are different for the two potentials and that neither potential agrees with experimental data. We argue that this implies that using the Stillinger–Weber or Tersoff potentials to predict trends in kappa as some system parameter is varied may yield results which are specific to the potential but not intrinsic to Si.
The Bravyi-Kitaev transformation for quantum computation of electronic structure
Authors: Seeley Jacob T. , Richard Martin J. , Love Peter J.
Published: December 2012

Quantum simulation is an important application of future quantum computers with applications in quantum chemistry, condensed matter, and beyond. Quantum simulation of fermionic systems presents a specific challenge. The Jordan-Wigner transformation allows for representation of a fermionic operator by O(n) qubit operations. Here, we develop an alternative method of simulating fermions with qubits, first proposed by Bravyi and Kitaev [Ann. Phys. 298, 210 (2002)10.1006/aphy.2002.6254; e-print arXiv:quant-ph/0003137v2], that reduces the simulation cost to O(log n) qubit operations for one fermionic operation. We apply this new Bravyi-Kitaev transformation to the task of simulating quantum chemical Hamiltonians, and give a detailed example for the simplest possible case of molecular hydrogen in a minimal basis. We show that the quantum circuit for simulating a single Trotter time step of the Bravyi-Kitaev derived Hamiltonian for H2 requires fewer gate applications than the equivalent circuit derived from the Jordan-Wigner transformation. Since the scaling of the Bravyi-Kitaev method is asymptotically better than the Jordan-Wigner method, this result for molecular hydrogen in a minimal basis demonstrates the superior efficiency of the Bravyi-Kitaev method for all quantum computations of electronic structure.
Electronic structure of CuCrO2 thin films grown on Al2O3(001) by oxygen plasma assisted molecular beam epitaxy
Authors: Shin D. , Foord J. S. , Egdell R. G. , Walsh A.
Published: December 2012

Thin films of CuCrO2 have been grown on Al2O3(001) substrates by oxygen plasma assisted molecular beam epitaxy. With a substrate temperature of 700 °C or 750 °C, the films showed an unanticipated (015) orientation but at a higher substrate temperature of 800 °C the expected basal (001) orientation predominates. The optical absorption spectrum of CuCrO2 shows a direct allowed absorption onset at 3.18 eV together with a weak peak at 2.0 eV which is suppressed by Sn doping. This suggests that the low energy peak should be attributed to 3d→3d excitations associated with Cu2+ defect states rather than excitations localised on Cr3+. Valence band X-ray photoemission spectra of (001) and (015) oriented CuCrO2 are compared with those obtained from polycrystalline samples.
The structure of Mn-doped tris(8-hydroxyquinoline)gallium by extended x-ray absorption fine structure spectroscopy and first principles calculations
Authors: Fang Shaojie , Pang Zhiyong , Du Yonghua , Zheng Lirong , Zhang Xijian , Wang Fenggong , Yuan Huimin , Han Shenghao
Published: December 2012

Metal-Mqx (M = Al, Ga, Zn, Be, and Ca, x = 2 or 3) complexes play a key role in organic spintronics and organic optoelectronics. However, the accurate structure determination of these complexes has been a challenge for a long time. Here, we report the structure of Mn-Gaq3 investigated by using first-principle density functional theory (DFT) calculations and extended X-ray absorption fine structure (EXAFS) spectroscopy. First, the structures of Mn-Gaq3 were predicted by first-principle DFT calculations. Then, all reasonable structures achieved from the calculations were used to fit the EXAFS spectra. By this method, the structure of Mn-Gaq3 is well obtained. We believe this method is also applicable to other metal-Mqx films.
Electrical and reliability characteristics of Mn-doped nano BaTiO3-based ceramics for ultrathin multilayer ceramic capacitor application
Authors: Gong Huiling , Wang Xiaohui , Zhang Shaopeng , Tian Zhibin , Li Longtu
Published: December 2012

Nano BaTiO3-based dielectric ceramics were prepared by chemical coating approach, which are promising for ultrathin multilayer ceramic capacitor (MLCC) applications. The doping effects of Mn element on the microstructures and dielectric properties of the ceramics were investigated. The degradation test and impedance spectroscopy were employed to study the resistance degradation and the conduction mechanism of Mn-doped nano-BaTiO3 ceramic samples. It has been found that the reliability characteristics greatly depended on the Mn-doped content. Moreover, the BaTiO3 ceramic with grain size in nanoscale is more sensitive to the Mn-doped content than that in sub-micron scale. The addition of 0.3 mol. % Mn is beneficial for improving the reliability of the nano BaTiO3-based ceramics, which is an important parameter for MLCC applications. However, further increasing the addition amount will deteriorate the performance of the ceramic samples.
Photocathode device using diamondoid and cesium bromide films
Authors: Clay William A. , Maldonado Juan R. , Pianetta Piero , Dahl Jeremy E. P. , Carlson Robert M. K. , Schreiner Peter R. , Fokin Andrey A. , Tkachenko Boryslav A. , Melosh Nicholas A. , Shen Zhi-Xun
Published: December 2012

A photocathode structure is presented that shows promise for use in high brightness electron sources. The structure consists of a metal substrate, a monolayer of a diamondoid derivative, and a thin film of cesium bromide. Diamondoid monolayers reduce the energy spread of electron emitters, while cesium bromide increases the yield and stability of cathodes. We demonstrate that the combined structure retains these properties, producing an emitter with lower energy spread than the corresponding cesium bromide emitter (1.06 eV versus 1.45 eV) and higher yield and stability than un-coated diamondoid emitters.
Cylindrically symmetric static solutions of the Einstein field equations for elastic matter
Authors: Brito I. , Carot J. , Mena F. C. , Vaz E. G. L. R.
Published: December 2012

The Einstein field equations are derived for a static cylindrically symmetric spacetime with elastic matter. The equations can be reduced to a system of two nonlinear ordinary differential equations and we present analytical and numerical solutions satisfying the dominant energy conditions. Furthermore, we show that the solutions can be matched at a finite radius to suitable Λ-vacuum exteriors given by the Linet-Tian spacetime.
High performance imaging streak camera for the National Ignition Facility
Authors: Opachich Y. P. , Kalantar D. H. , MacPhee A. G. , Holder J. P. , Kimbrough J. R. , Bell P. M. , Bradley D. K. , Hatch B. , Brienza-Larsen G. , Brown C. , Brown C. G. , Browning D. , Charest M. , Dewald E. L. , Griffin M. , Guidry B. , Haugh M. J. , Hicks D. G. , Homoelle D. , Lee J. J. , Mackinnon A. J. , Mead A. , Palmer N. , Perfect B. H. , Ross J. S. , Silbernagel C. , Landen O.
Published: December 2012

An x-ray streak camera platform has been characterized and implemented for use at the National Ignition Facility. The camera has been modified to meet the experiment requirements of the National Ignition Campaign and to perform reliably in conditions that produce high electromagnetic interference. A train of temporal ultra-violet timing markers has been added to the diagnostic in order to calibrate the temporal axis of the instrument and the detector efficiency of the streak camera was improved by using a CsI photocathode. The performance of the streak camera has been characterized and is summarized in this paper. The detector efficiency and cathode measurements are also presented.
A high precision instrument to measure angular and binocular deviation introduced by aircraft windscreens by using a shadow casting technique
Authors: Shivananju B. N. , Yamdagni S. , Vasu R. M. , Asokan S.
Published: December 2012

Objects viewed through transparent sheets with residual non-parallelism and irregularity appear shifted and distorted. This distortion is measured in terms of angular and binocular deviation of an object viewed through the transparent sheet. The angular and binocular deviations introduced are particularly important in the context of aircraft windscreens and canopies as they can interfere with decision making of pilots especially while landing, leading to accidents. In this work, we have developed an instrument to measure both the angular and binocular deviations introduced by transparent sheets. This instrument is especially useful in the qualification of aircraft windscreens and canopies. It measures the deviation in the geometrical shadow cast by a periodic dot pattern trans-illuminated by the distorted light beam from the transparent test specimen compared to the reference pattern. Accurate quantification of the shift in the pattern is obtained by cross-correlating the reference shadow pattern with the specimen shadow pattern and measuring the location of the correlation peak. The developed instrument is handy to use and computes both angular and binocular deviation with an accuracy of less than ±0.1 mrad (≈0.036 mrad) and has an excellent repeatability with an error of less than 2%.
Toward an improved understanding of the AsH2 free radical: Laser spectroscopy, ab initio calculations, and normal coordinate analysis
Authors: Grimminger Robert A. , Clouthier Dennis J.
Published: December 2012

Spectra of the $\tilde A^2 A_1 \hbox{—} \tilde X^2 B_1$Ã2A1—X̃2B1 transition of the jet-cooled AsD2 and AsHD isotopologues of the arsino radical have been studied by laser induced fluorescence and wavelength resolved emission techniques. A high-resolution spectrum of the AsD2 $0_0^0 $000 band has been recorded, and an improved r0 structure [$r_0^\prime $r0′ = 1.487(4) Å, $\theta _0^\prime $θ0′ = 123.0(2)°] for the $\tilde A$Ã state has been determined from the rotational constants. To aid in the analysis of the vibrational levels, an ab initio potential energy surface of the $\tilde X^2 B_1$X̃2B1 state has been constructed and the rovibronic energy levels of states on that potential have been determined using a variational method. The vibrational levels observed in wavelength resolved emission spectra have been fitted to a local mode Hamiltonian with most anharmonic parameters fixed at ab initio values, and the resulting harmonic frequencies have been used to perform a normal coordinate analysis which yielded an improved set of quadratic force constants and an estimate of the equilibrium ground state structure.
Direct and inverse scattering for nonlinear Schrödinger equation in 2D
Authors: Serov Valery , Harju Markus , Fotopoulos Georgios
Published: December 2012

We discuss the scattering theory for the nonlinear Schrödinger equation \documentclass[12pt]{minimal}\begin{document}$-\Delta u(x)\break + h(x,|u(x)|)u(x) = k^{2}u(x), x \in \mathbb {R}^2,$\end{document}−Δu(x)+h(x,|u(x)|)u(x)=k2u(x),x∈R2, where h is a very general and possibly singular combination of potentials. We prove that the direct scattering problem has a unique bounded solution. We establish also the asymptotic behaviour of scattering solutions. A uniqueness result and a representation formula is proved for the inverse scattering problem with general scattering data. The method of Born approximation is applied for the recovery of local singularities and jumps.
Temperature-dependent capacitance-voltage analysis of defects in Al2O3 gate dielectric stacks on GaN
Authors: Long Rathnait D. , Hazeghi Aryan , Gunji Marika , Nishi Yoshio , McIntyre Paul C.
Published: December 2012

Capacitance-voltage measurements of Pd/atomic layer deposited Al2O3/GaN metal oxide semiconductor capacitors performed over a temperature range of 77 K-500 K are reported. Border trap response is not detected in these measurements, consistent with the energy levels of bulk Al2O3 defects predicted in reported first principles calculations. The limitations of the conductance method for estimation of the interface state density of the wide band gap GaN semiconductor, even at a measurement temperature of 500 K, are discussed. As GaN-based devices are intended for high temperature applications, the role of the pyroelectric effect in the interpretation of higher-temperature capacitance-voltage data is described.
Confocal sample-scanning microscope for single-molecule spectroscopy and microscopy with fast sample exchange at cryogenic temperatures
Authors: Hussels Martin , Konrad Alexander , Brecht Marc
Published: December 2012

The construction of a microscope with fast sample transfer system for single-molecule spectroscopy and microscopy at low temperatures using 2D/3D sample-scanning is reported. The presented construction enables the insertion of a sample from the outside (room temperature) into the cooled (4.2 K) cryostat within seconds. We describe the mechanical and optical design and present data from individual Photosystem I complexes. With the described setup numerous samples can be investigated within one cooling cycle. It opens the possibility to investigate biological samples (i) without artifacts introduced by prolonged cooling procedures and (ii) samples that require preparation steps like plunge-freezing or specific illumination procedures prior to the insertion into the cryostat.
Effect of microalloying on the toughness of metallic glasses
Authors: Garrett Glenn R. , Demetriou Marios D. , Chen Jason , Johnson William L.
Published: December 2012

The effect of microalloying on the toughness of Cu-Ti-based metallic glasses is explored. Minor additions of Si and Sn in glass former Cu47Ti34Zr11Ni8 known to improve glass-forming ability are found here to sharply decrease toughness. The drop in toughness is associated with a small but meaningful increase in shear modulus, glass-transition temperature, yield strength, and a decrease in Poisson's ratio, implying a negative correlation between toughness and shear flow barrier. The strong influence of minor additions on the glass properties could be a useful tool for simultaneously tuning both the glass-forming ability and toughness of metallic glasses.
Ultralow VπL values in suspended quantum well waveguides
Authors: Stievater T. H. , Park D. , Rabinovich W. S. , Pruessner M. W. , Kanakaraju S. , Richardson C. J. K. , Khurgin J. B.
Published: December 2012

We demonstrate VπL values in the optical L-band in suspended quantum well waveguides between 109 and 199 mV cm. This low VπL value results from very strong out-of-plane modal confinement due to the large semiconductor-air refractive index contrast both above and below the waveguide. The measured phase shifts are consistent with a model of waveguide electrorefraction based on the Pockels effect and the quantum confined Stark effect.
Suppression of relaxation in (202¯1) InGaN/GaN laser diodes using limited area epitaxy
Authors: Hardy Matthew T. , Nakamura Shuji , Speck James S. , DenBaars Steven P.
Published: December 2012

Confinement factor (Γ) of semipolar (202¯1) green laser diodes (LDs) is limited by relaxation of coherency stresses in the waveguiding heterostructure. In this paper, we demonstrate the suppression of relaxation by blocking glide of pre-existing threading dislocations using limited area epitaxy (LAE). With LAE, we show a factor of three increase in thickness before the observation of significant misfit dislocation formation for (202¯1) oriented In0.08Ga0.92N/GaN heterostructures. We then apply this technique to fabricate coherent AlGaN-cladding-free LDs with 73% enhanced Γ relative to planar devices without LAE, having an emission wavelength of 495 nm and threshold current density of 10.7 kA/cm2. This technique is readily applicable to AlGaN or AlInGaN cladding in addition to InGaN waveguiding layers to improve Γ of semipolar LDs.
Fabrication of free-standing highly conducting ultrananocrystalline diamond films with enhanced electron field emission properties
Authors: Sankaran K. J. , Chen H. C. , Lee C. Y. , Tai N. H. , Lin I. N.
Published: December 2012

Fabrication of free-standing/highly conducting ultrananocrystalline diamond (fc-UNCD) films at low growth temperature (<475 °C) is demonstrated. The fc-UNCD films show high conductivity of σ = 146 (Ω cm)−1 with superior electron field emission (EFE) properties, viz. low turn-on field of 4.35 V/μm and high EFE current density of 3.76 mA/cm2 at an applied field of 12.5 V/μm. Transmission electron microscopy examinations reveal the presence of Au/Cu clusters in film-to-substrate interface, which consequences in the induction of nanographite phases, surrounding the diamond grains that form conduction channels for electrons transport, ensuing in marvelous EFE properties of fc-UNCD films.
Dielectrophoresis based discrimination of human embryonic stem cells from differentiating derivatives
Authors: Velugotla Srinivas , Pells Steve , Mjoseng Heidi K. , Duffy Cairnan R. E. , Smith Stewart , De Sousa Paul , Pethig Ronald
Published: December 2012

Assessment of the dielectrophoresis (DEP) cross-over frequency (fxo), cell diameter, and derivative membrane capacitance (Cm) values for a group of undifferentiated human embryonic stem cell (hESC) lines (H1, H9, RCM1, RH1), and for a transgenic subclone of H1 (T8) revealed that hESC lines could not be discriminated on their mean fxo and Cm values, the latter of which ranged from 14 to 20 mF/m2. Differentiation of H1 and H9 to a mesenchymal stem cell-like phenotype resulted in similar significant increases in mean Cm values to 41–49 mF/m2 in both lines (p < 0.0001). BMP4-induced differentiation of RCM1 to a trophoblast cell-like phenotype also resulted in a distinct and significant increase in mean Cm value to 28 mF/m2 (p < 0.0001). The progressive transition to a higher membrane capacitance was also evident after each passage of cell culture as H9 cells transitioned to a mesenchymal stem cell-like state induced by growth on a substrate of hyaluronan. These findings confirm the existence of distinctive parameters between undifferentiated and differentiating cells on which future application of dielectrophoresis in the context of hESC manufacturing can be based.
Note: Energy convexity and density matrices in molecular systems
Authors: Bochicchio Roberto C. , Rial Diego
Published: December 2012

A novel appropriate definition for the density matrix for an interacting Coulombic driven atomic or molecular system with non-integer number of particles is given. Our approach leads to a direct derivation of the proposal reported by Perdew et al. [Phys. Rev. Lett. 49, 1691 (1982)]10.1103/PhysRevLett.49.1691 and points out its suitability and perspective advances.
Electrical transduction in nanomechanical resonators based on doubly clamped bottom-up silicon nanowires
Authors: Sansa Marc , Fernández-Regúlez Marta , San Paulo Álvaro , Pérez-Murano Francesc
Published: December 2012

The frequency response of double-clamped bottom-up grown silicon nanowires is measured electrically by means of a frequency modulation (FM) detection scheme. In comparison with other electrical methods, FM detection is simpler and it allows the use of smaller actuation signals. We have been able to resolve the first three mechanical resonance modes up to frequencies higher than 350 MHz. The FM detection scheme relies on a transduction mechanism that presents a linear dependence of the change of conductance with the nanowire deflection/actuation signal. The modeling of the system corroborates that two different transduction mechanisms (linear and quadratic) co-exist.
The Maxwell-Wagner model for charge transport in ambipolar organic field-effect transistors: The role of zero-potential position
Authors: Mashiko Yasuhiro , Taguchi Dai , Weis Martin , Manaka Takaaki , Iwamoto Mitsumasa
Published: December 2012

Charge transport in an ambipolar organic field-effect transistors (OFETs) is discussed in accordance to the potential profiles reconstructed from the electric-field induced second-harmonic generation experiment. The Maxwell-Wagner model based on drift-diffusion equation in OFET is used for the potential profile analysis. A good agreement between dielectric model and the experiment suggests importance of the space-charge field effects in the design of the ambipolar light-emitting OFETs. Further, the highest enhancement of the electric field is on zero-potential position in the channel, which represents the meeting point of electrons and holes and is an origin of the electroluminescence.
Strain controlled ferroelectric switching time of BiFeO3 capacitors
Authors: Guo E. J. , Dörr K. , Herklotz A.
Published: December 2012

The ferroelectric switching kinetics of BiFeO3 capacitors grown on a piezoelectric substrate has been investigated in different strain states and at various temperatures. The switching behavior is in good agreement with the Kolmogorov-Avrami-Ishibashi model. The effect of reversible biaxial in-plane compression on the switching time is an enhancement at low electric field and a reduction at high field. The two field regimes are found to correspond to the creep and the depinning of domain walls. The strain effect on the switching time depends strongly on temperature and reaches a tenfold slowing down upon ∼0.1% of biaxial compression at 50 K. This work provides a route to realize strain control of ferroelectric switching kinetics in BiFeO3 and is significant for potential applications.
Influence of phosphorescent dopants in organic light-emitting diodes with an organic homojunction
Authors: Yun Changhun , Lee Jonghee , Lee Jaehyun , Lüssem Björn , Ventsch Fabian , Leo Karl , Gather Malte C.
Published: December 2012

We report on phosphorescent homojunction organic light-emitting diodes (HJOLEDs) using p-i-n structures based on a single ambipolar organic semiconductor, 4,4′-Bis(carbazol-9-yl)-biphenyl, as matrix organic materials. In HJOLEDs, the phosphorescent dopant molecules play an important role in controlling the charge balance inside the emissive layer. We observe a four-fold enhancement in the luminous efficacy at 1000 cd/m2 from 3.7% to 12.9% by varying the emitter molecule. The influence of the energy level of the emitter molecule on charge balance is investigated by analyzing current density vs. voltage curves with the trap-limited current theory and by analyzing the electroluminescence spectra.
Magneto-optical fiber sensor based on bandgap effect of photonic crystal fiber infiltrated with magnetic fluid
Authors: Zu Peng , Chiu Chan Chi , Gong Tianxun , Jin Yongxing , Chang Wong Wei , Dong Xinyong
Published: December 2012

A magnetic field sensor based on combination of the magnetic fluid and the tunable photonic bandgap effect of photonic crystal fiber is proposed. The magnetic fluid with higher refractive index (>1.45) is prepared and filled into the air-holes of photonic crystal fiber to convert the index guiding fiber into photonic bandgap fiber. The proposed sensor takes full advantage of the ultrahigh sensitivity characteristic of photonic bandgap fiber and achieves a high sensitivity and resolution of 1.56 nm/Oe and 0.0064 Oe, respectively, which are 2-3 orders of magnitude better than other sensors based on magnetic fluid.
Quantitative self-calibrating lock-in carrierographic lifetime imaging of silicon wafers
Authors: Sun Qiming , Melnikov Alexander , Mandelis Andreas
Published: December 2012

Quantitative self-calibrating lock-in carrierography (LIC) imaging of crystalline silicon wafers is introduced using an InGaAs camera and a spread super-bandgap illumination laser beam. Images at several modulation frequencies and a simplified model based on photocarrier radiometric theory are used to construct the effective carrier lifetime image from the phase-frequency dependence. The phase image data at several frequencies and at selected locations on a wafer were compared to frequency scans obtained with a single-element InGaAs detector, and good agreement was found. The quantitative LIC lifetime imaging capability demonstrated in this work is self-calibrating and eliminates the requirement for calibration in conventional photoluminescence imaging.
Reduced graphene oxide coated thin aluminum film as an optoacoustic transmitter for high pressure and high frequency ultrasound generation
Authors: Hwan Lee Seok , Park Mi-ae , Yoh Jack J. , Song Hyelynn , Yun Jang Eui , Hyup Kim Yong , Kang Sungchan , Seop Yoon Yong
Published: December 2012

We demonstrate that reduced graphene oxide (rGO) coated thin aluminum film is an effective optoacoustic transmitter for generating high pressure and high frequency ultrasound previously unattainable by other techniques. The rGO layer of different thickness is deposited between a 100 nm-thick aluminum film and a glass substrate. Under a pulsed laser excitation, the transmitter generates enhanced optoacoustic pressure of 64 times the aluminum-alone transmitter. A promising optoacoustic wave generation is possible by optimizing thermoelasticity of metal film and thermal conductivity of rGO in the proposed transmitter for laser-induced ultrasound applications.
Switching spectroscopic measurement of surface potentials on ferroelectric surfaces via an open-loop Kelvin probe force microscopy method
Authors: Li Qian , Liu Yun , Wang Danyang , Withers Ray L. , Li Zhenrong , Luo Haosu , Xu Zhuo
Published: December 2012

We report a method for switching spectroscopy Kelvin probe force microscopy (SS-KPFM). The method is established as a counterpart to switching spectroscopy piezoresponse force microscopy (SS-PFM) in Kelvin probe force microscopy. SS-KPFM yields quantitative information about the surface charge state during a local bias-induced polarization switching process, complementary to the electromechanical coupling properties probed via SS-PFM. Typical ferroelectric samples of a Pb-based relaxor single crystal and a BiFeO3 thin film were investigated using both methods. We briefly discuss the observed surface charging phenomena and their influence on the associated piezoresponse hysteresis loops.