bluuebunny/crossref_metadata_2025 huggingface dataset:
Tillage and Soybean Canopy Effects on Common Cocklebur (Xanthium strumarium) Emergence
Authors: Norsworthy Jason K. , Oliveira Marcos J.
Published: August 2007

Field experiments were conducted in Pendleton, SC, in 2004 and 2005, to determine the influence of tillage with or without soybean on common cocklebur emergence. Treatments included no-till/no soybean (NTNS), no-till plus soybean (NTS), tillage/no soybean (TNS), and tillage plus soybean (TS). Emergence was monitored from an artificial seed bank in 2004 and a natural seed bank in 2005. Overall, common cocklebur emerged from early May through late October and presented multiple emergence. In no-till plots with or without soybean, initial emergence was delayed 7 d in both years. In TNS plots, major emergence (daily emergence > mean emergence plus standard deviation) of common cocklebur occurred from early May to late July. In NTNS plots, major emergence occurred from late May through late August. No-till reduced total common cocklebur emergence by 59 to 69% compared with tillage. At the V5 to V6 soybean growth stage, the daily soil thermal fluctuation at 2.5 cm soil depth diminished from approximately 15 to 5 C and reduced common cocklebur emergence by 84 to 91% for the rest of the growing season. Common cocklebur emergence was higher when the mean soil temperature was > 15 C, and the daily thermal fluctuation was > 7.5 C. This study suggests that strategies that promote early crop canopy development and minimum tillage should reduce common cocklebur emergence.
Evaluating Phenological Indicators for Predicting Giant Foxtail (Setaria faberi) Emergence
Authors: Cardina John , Herms Catherine P. , Herms Daniel A. , Forcella Frank
Published: August 2007

We evaluated the use of ornamental plants as phenological indicators for predicting giant foxtail emergence and compared their performance with predictions based upon Julian day, cumulative growing degree–days (GDD), and the WeedCast program. From 1997 to 2001, we monitored giant foxtail emergence in a field experiment with and without fall and spring tillage to estimate the dates of 25, 50, and 80% emergence; we also recorded dates of first and full bloom of 23 ornamental plant species. Dates of weed emergence and ornamental blooming for 1997 to 2000 were compiled in a phenological calendar consisting of 54 phenological events for each year, and events were ordered by average (1997 to 2000) cumulative GDD (January 1 start date, 10 C base temperature). Bloom events occurring just before the giant foxtail emergence events were chosen as the phenological indicators for 2001. The Julian day method used the average (1997 to 2000) dates of foxtail emergence to predict 2001 emergence. The GDD model (October 1 start date, 0 C base temperature) was chosen by determining the combination of start date and base temperature that provided the lowest coefficient of variation for the 1997 to 2000 data. The WeedCast prediction was generated using local soil and environmental data from 2001. The rank order of the 54 phenological events in 2001 showed little deviation from the 4-yr (1997 to 2000) average rank order (R2= 0.96). The phenological calendar indicated that, on average, 25% of giant foxtail seedlings had emerged when red chokeberry was in first bloom, and 80% of seedlings had emerged around the time multiflora rose was in full bloom. We compared the phenological calendar predictions for 25, 50, and 80% emergence with those based on Julian day, cumulative GDD, and WeedCast. The average deviation in predictions ranged from 4.4 d for the phenological calendar to 11.4 d for GDD. In addition to being generally more accurate, the phenological calendar approach also offers the advantage of providing information on the order of phenological events, thus helping to anticipate the progress of emergence and to plan and implement management strategies.
Variation in Wild Proso Millet (Panicum miliaceum) Fecundity in Sweet Corn Has Residual Effects in Snap Bean
Authors: Davis Adam S. , Williams Martin M.
Published: August 2007

Bioeconomic models are predicated upon the relationship between weed fecundity and crop yield loss in consecutive growing seasons, yet this phenomenon has received few empirical tests. Residual effects of wild proso millet (WPM) fecundity in sweet corn upon WPM seedling recruitment, weed management efficacy, and crop yield within a subsequent snap bean crop were investigated with field experiments in Urbana, IL, in 2005 and 2006. WPM fecundity in sweet corn showed strong positive associations with WPM seedbank density, seedling recruitment, and demographic transitions within snap bean. A negative exponential relationship between WPM initial seedling density and seedling survival of a single rotary hoe pass indicated that the rotary hoe was ineffective at low weed population densities, but its efficacy increased with increasing weed population density to a maximum of 75% seedling mortality. Efficacy of postemergent chemical control of WPM was unaffected by WPM population density. Path analysis models demonstrated dependence between WPM fecundity in sweet corn, WPM seedling recruitment in snap bean, and reductions in snap bean yield in subsequent growing season, mediated by negative impacts of WPM seedling establishment on snap bean stand. These results underscore the importance of expanding integrated weed management programs to include management of annual weed populations both at the end of their life cycle, by reducing fecundity and seed survival, and at the very beginning of their life cycle, by reducing seedling recruitment and establishment.
Ceramics, Material Properties of
Authors: Shackelford James F.
Published: August 2007

The article contains sections titled:

Introduction

Ceramic Science and Technology

Categories of Ceramic Materials

Silicate Ceramics

Nonsilicate Oxide Ceramics

Nonoxide Ceramics

Glass–Ceramics

Ceramic Composite Systems

Cermets

Ceramic–Matrix Composites

Ceramic Processing

Traditional Methods

Recent Advances

Mechanical Properties

Brittle Fracture

Elastic Constants

Fracture Strength

Fracture Mechanics

Static Fatigue

Creep Deformation

Thermal Shock

Viscoelastic Deformation of Glassy Phases

Optical Properties

Refraction

Reflection

Transmission

Electrical Properties

Conductivity of Traditional Ceramics

Superconducting Ceramics

Dielectrics

Ferroelectrics and Piezoelectrics

Magnetic Properties

Ferrimagnetism

Superconducting Magnets
Crystallography
Authors: Pearson W. B. , Chieh C.
Published: August 2007

The article contains sections titled:

Introduction

the Crystalline State

Unit Cells and Crystal Systems

Lattices

Point‐Group Symmetry

Space Groups

Lattice Planes and Crystal Faces

The Reciprocal Lattice

Crystal Structure Determination

Radiations for Crystallography

X‐Ray Emission Spectra

X‐Ray Atomic‐Scattering Factors

Neutron Atomic‐Scattering Factors

X‐Ray Crystal Structure Analysis with Single Crystals

The
L
aue Methods

Cylindrical‐Film Methods

Precession Methods

Diffractometers

Macromolecule Crystallography

X‐Ray Analysis of Polycrystalline Samples

Other Diffraction Methods

Neutron Diffraction

Electron Diffraction

the Results of Crystal Structure Determinations

Metals

Insulators/Semiconductors

Molecular Crystals

Assessment and Collation of Crystal Structure Data

Crystallography in Industry and Medicine

Epilogue
Diamagnetism
Authors: Falicov Leopoldo M.
Published: August 2007

The article contains sections titled:

Introduction

Thermodynamic Arguments

Diamagnetism of Atoms, Molecules, and Molecular Solids

H
amiltonian of Electrons in a Magnetic Field

L
angevin Theory for Closed‐Shell Systems

Orbital Diamagnetism of Metallic Electrons

Quantization of Itinerant Electrons in a Magnetic Field

L
andau Diamagnetism

The
d
e
H
aas–van
A
lphen Effect

Diamagnetism in Superconductors

The
M
eissner Effect

The
L
ondon Theory

The
G
inzburg–
L
andau Theory

General Formulation

Penetration Depth and Coherence Length

Flux Quantization

Phase‐Current Relationship; The
J
osephson Effect

Magnetic‐Field Dependence of the Order Parameter

Quantum Interference Phenomena

Conclusion
Electrochemistry
Authors: Adžić Radoslav R. , Yeager Ernest B.
Published: August 2007

The article contains sections titled:

Introduction

the Structure of Electrode–electrolyte Interfaces

Potential Concepts in Electrochemistry

The Electrical Double Layer

New Models

Charge‐transfer Reactions

Phenomenological Description of the Kinetics of Charge‐Transfer Processes

Theories of Electron Transfer

Theories of Proton Transfer

Electrosorption Reactions

Partial Charge Transfer During Specific Ionic Adsorption

Electrochemistry On Well‐defined Single‐crystal Surfaces

Double‐Layer Capacitance Studies

Electrosorption of Hydrogen and Oxygen on Noble‐Metal Electrodes

Formation of Metal Monolayers

Electrocatalytic Reactions

Electronic Factors

Structural Factors in Electrocatalysis

Semiconductor Electrodes

Space‐Charge Effects

Electrons, Holes, and Surface States in Electrode Reactions

Photoeffects at Semiconductor Electrodes

Techniques For the Study of Electrochemical Interfaces and Electrode Processes

Electrochemical Techniques

In SituandEx SituSpectroscopic and Surface‐Physics Techniques

uv–Visible Reflectance Spectroscopy and Ellipsometry

Infrared Reflectance Spectroscopy and Raman Scattering from Electrode Surfaces

EXAFSand Surface X‐Ray Diffraction

Photoemission of Electrons from a Metal into Solution

Scanning Tunneling Microscopy

Ex SituStudies by Surface‐Physics Techniques

Applied Electrochemistry

Batteries

Fuel Cells

Large‐Scale Industrial Processes

Inorganic and Organic Electrosynthesis

Electroplating

Electrochemical Sensors

Corrosion and Corrosion Protection

Challenging Problems For the Future

Challenging Opportunities in Electrochemistry
Galaxies and Cosmology
Authors: Layzer David
Published: August 2007

The article contains sections titled:

Introduction

Ancient and Classical Cosmology

Greek Cosmology

The Revival of Greek Cosmology

Newton's Cosmology

Kant andLaplace

Cosmology in the 19thCentury

the Milky Way and Other Galaxies

Cepheids as Distance Indicators

Shapley's Galaxy

The Role of Dust

Galactic Rotation

The Nature of Spiral Nebulae

Composition of Galaxies

Galaxy Types

Chemical Composition and Age

“THE REALM OF THE NEBULAE”

The Cosmological Principle

The Cosmic Expansion

The Spatial Distribution of Galaxies

Prevalence of Dark Matter

The Cosmic Microwave Background

The Age of the Universe

Modern Cosmology

Relativistic Cosmology

The Primordial Fireball

Origin of Helium and Other Light Elements

The Primordial Fireball and Particle Physics

Phase Transitions, Domain Walls, and Magnetic Monopoles

Inflationary Cosmology

Origin and Growth of Density Fluctuations in the Fireball

The Vacuum–Energy Problem

A Cold Universe?

The Cold Universe and Particle Physics
Cholinergic innervation of the zebrafish olfactory bulb
Authors: Edwards Jeffrey G. , Greig Ann , Sakata Yoko , Elkin Dimitry , Michel William C.
Published: August 2007

A number of fish species receive forebrain cholinergic input but two recent reports failed to find evidence of cholinergic cell bodies or fibers in the olfactory bulbs (OBs) of zebrafish. In the current study we sought to confirm these findings by examining the OBs of adult zebrafish for choline acetyltransferase (ChAT) immunoreactivity. We observed a diffuse network of varicose ChAT‐positive fibers associated with the nervus terminalis ganglion innervating the mitral cell/glomerular layer (MC/GL). The highest density of these fibers occurred in the anterior region of the bulb. The cellular targets of this cholinergic input were identified by exposing isolated OBs to acetylcholine receptor (AChR) agonists in the presence of agmatine (AGB), a cationic probe that permeates some active ion channels. Nicotine (50 μM) significantly increased the activity‐dependent labeling of mitral cells and juxtaglomerular cells but not of tyrosine hydroxlase‐positive dopaminergic neurons (TH+ cells) compared to control preparations. The nAChR antagonist mecamylamine, an α7‐nAChR subunit‐specific antagonist, calcium‐free artificial cerebrospinal fluid, or a cocktail of ionotropic glutamate receptor (iGluR) antagonists each blocked nicotine‐stimulated labeling, suggesting that AGB does not enter the labeled neurons through activated nAChRs but rather through activated iGluRs following ACh‐stimulated glutamate release. Deafferentation of OBs did not eliminate nicotine‐stimulated labeling, suggesting that cholinergic input is primarily acting on bulbar neurons. These findings confirm the presence of a functioning cholinergic system in the zebrafish OB. J. Comp. Neurol. 504:631–645, 2007. © 2007 Wiley‐Liss, Inc.
Initiation Pressure Thresholds from Three Sources
Authors: Souers P. Clark , Vitello Peter
Published: August 2007

Pressure thresholds are minimum pressures needed to start explosive initiation that ends in detonation. We obtain pressure thresholds from three sources. Run‐to‐detonation times are the poorest source but the fitting of a function gives rough results. Flyer‐induced initiation gives the best results because the initial conditions are the best known. However, very thick flyers are needed to give the lowest, asymptotic pressure thresholds used in modern models and this kind of data is rarely available. Gap test data are in much larger supply but the various test sizes and materials are confusing. We find that explosive pressures are almost the same if the distance in the gap test spacers are in units of donor explosive radius. Calculated half‐width time pulses in the spacers may be used to create a pressure‐time curve similar to that of the flyers. The very‐large Eglin gap tests give asymptotic thresholds comparable to extrapolated flyer results. The three sources are assembled into a much‐expanded set of near‐asymptotic pressure thresholds. These thresholds vary greatly with density: for TATB/LX‐17/PBX 9502, we find values of 4.9 and 8.7 GPa at 1.80 and 1.90 g/cm3, respectively.
Kinetics of Solid Polymorphic Phase Transitions of CL‐20
Authors: Li Jun , Brill Thomas B.
Published: August 2007

Solid‐solid phase transitions of the CL‐20 polymorphs ε→γ, α→γ, and β→γ were studied isothermally at ambient pressure by transmission FT‐IR spectroscopy and analyzed by multivariate regression. Activation energies as function of the extent of conversion were obtained using the model‐free isoconversional method. The apparent activation energies for all three solid phase transformations were about 210 kJ/mol at 5% conversion, and compared well with the calculated lattice energies. The apparent activation energies increased to a maximum of about 400 kJ/mol at 40%, 80% and 60% conversion for ε→γ, α→γ, and β→γ, respectively, and then decreased. The mechanisms of the phase transitions of CL‐20 appear to be quite complex. Comparisons are made with the phase transitions of HMX.
A new class of rank-one transformations with singular spectrum
Authors: EL ABDALAOUI EL HOUCEIN
Published: August 2007

We introduce a new tool to study the spectral type of rank-one transformations using the method of the central limit theorem for trigonometric sums. We get some new applications.
Chain recurrence, growth rates and ergodic limits
Authors: COLONIUS FRITZ , FABBRI ROBERTA , JOHNSON RUSSELL
Published: August 2007

Averages of functionals along trajectories are studied by evaluating the averages along chains. This yields results for the possible limits and, in particular, for ergodic limits. Applications to Lyapunov exponents and to concepts of rotation numbers of linear Hamiltonian flows and of general linear flows are given.
Late Quaternary changes in intermediate water oxygenation and oxygen minimum zone, northern Japan: A benthic foraminiferal perspective
Authors: Shibahara Akihiko , Ohkushi Ken'ichi , Kennett James P. , Ikehara Ken
Published: August 2007

A strong oxygen minimum zone (OMZ) currently exists at upper intermediate water depths on the northern Japanese margin, NW Pacific. The OMZ results largely from a combination of high surface water productivity and poor ventilation of upper intermediate waters. We investigated late Quaternary history (last 34 kyr) of ocean floor oxygenation and the OMZ using quantitative changes in benthic foraminiferal assemblages in three sediment cores taken from the continental slope off Shimokita Peninsula and Tokachi, northern Japan, at water depths between 975 and 1363 m. These cores are well located within the present‐day OMZ, a region of high surface water productivity, and in close proximity to the source region of North Pacific Intermediate Water. Late Quaternary benthic foraminiferal assemblages experienced major changes in response to changes in dissolved oxygen concentration in ocean floor sediments. Foraminiferal assemblages are interpreted to represent three main groups representing oxic, suboxic, and dysoxic conditions. Assemblage changes in all three cores and hence in bottom water oxygenation coincided with late Quaternary climatic episodes, similar to that known for the southern California margin. These episodes, in turn, are correlated with orbital and millennial climate episodes in the Greenland ice core including the last glacial episode, Bølling‐Ållerød (B/A), Younger Dryas, Preboreal (earliest Holocene), early Holocene, and late Holocene. The lowest oxygen conditions, marked by dysoxic taxa and laminated sediments in one core, occurred during the B/A and the Preboreal intervals. Suboxic taxa dominated mainly during the last glacial, the Younger Dryas, and most of the Holocene. Dysoxic conditions during the B/A and Preboreal intervals in this region were possibly caused by high surface water productivity at times of reduced intermediate ventilation in the northwestern Pacific. Remarkable similarities are evident in the late Quaternary sequence of benthic foraminiferal assemblage change between the two very distant continental margins of northern Japan and southern California. The oscillations in OMZ strength, reflected by these faunal changes, were widespread and apparently synchronous over wide areas of the North Pacific, reflecting broad changes in intermediate water ventilation and surface ocean productivity closely linked with late Quaternary climate change on millennial and orbital timescales.
SERSIO: Svalbard EISCAT Rocket Study of Ion Outflows
Authors: Frederick‐Frost K. M. , Lynch K. A. , Kintner P. M. , Klatt E. , Lorentzen D. , Moen J. , Ogawa Y. , Widholm M.
Published: August 2007

The SERSIO sounding rocket was launched from Ny‐Alesund, Svalbard, into a type 2 ion upflow event simultaneously observed by the European Incoherent Scatter (EISCAT) radar facility in Longyearbyen on 22 January 2004 at 0857 UT. It reached an apogee of 782 km. In situ wave data and thermal particle measurements in the cusp/cleft region clearly show core thermal ion temperature enhancements up to 0.8 eV in association with 0–4 kHz broadband extremely low frequency wave activity (BBELF). The in situ observation of wave heating in the cusp/cleft region at these low altitudes (520–780 km) and high densities (80,000/cm3) is an important measurement and should be included in any model of ion energization. Wave activity in the form of naturally enhanced ion acoustic lines (NEIAL) was seen by the EISCAT radar in the same activity region. Periods of NEIAL were compared with in situ auroral electron data that show no evidence of a bump‐on‐tail distribution; thus our data do not support using Langmuir turbulence to explain these radar echoes. In contrast, these observations associating NEIAL with BBELF activity suggest that they may be the same phenomenon. During these comparisons, all‐sky camera images were used to verify similar environmental conditions between the rocket and radar measurement volumes, while the spatial separation between the volumes was less than 500 km. In situ measurements also confirm the link between soft electron precipitation and thermal electron temperature enhancements in this ion upflow environment.
Surface wave tomography of the upper mantle beneath the Reykjanes Ridge with implications for ridge–hot spot interaction
Authors: Delorey Andrew A. , Dunn Robert A. , Gaherty James B.
Published: August 2007

We modeled fundamental mode Love and Rayleigh waves to study the seismic properties of the upper mantle beneath the Reykjanes Ridge. These waves were generated by regional earthquakes occurring in the North Atlantic to the south of Iceland and were recorded by stations located on Iceland. Over 12,000 measurements of the phase, group arrival time, and amplitude of narrow‐pass‐filtered waveforms (over the period range of 9.5–100 s) were used to solve for mantle shear wave velocity structure and anisotropy. In a vertical plane oriented normal to the ridge axis, the velocity structure contains a broad and deep low‐velocity zone in the upper mantle beneath the ridge. A joint analysis of the seismic structure with gravity data reveals that the low velocities are consistent with elevated temperatures (∼75°). Our study shows that plume material spreads broadly outward beneath the Reykjanes Ridge from Iceland and is not confined to a narrow lithospheric channel. At distances >200 km from the ridge, shear wave anisotropy indicates a predominant horizontal alignment of the fast axes of anisotropic crystals (mainly above 50 km depth), which can be interpreted as past, horizontal, ridge‐perpendicular flow. Within ±200 km of the ridge the anisotropy indicates a general vertical alignment of the fast axes or an alignment such that the fast axes point along the ridge. The transition to this type of anisotropy coincides with the appearance of increased hot spot–ridge interaction ∼20 Myr ago, indicating that plume flow has largely disrupted mantle flow beneath the ridge since that time.
Assessment of shock wave lithotripters via cavitation potential
Authors: Iloreta Jonathan I. , Zhou Yufeng , Sankin Georgy N. , Zhong Pei , Szeri Andrew J.
Published: August 2007

A method to characterize shock wave lithotripters by examining the potential for cavitation associated with the lithotripter shock wave (LSW) has been developed. The method uses the maximum radius achieved by a bubble subjected to a LSW as a representation of the cavitation potential for that region in the lithotripter. It is found that the maximum radius is determined by the work done on a bubble by the LSW. The method is used to characterize two reflectors: an ellipsoidal reflector and an ellipsoidal reflector with an insert. The results show that the use of an insert reduced the −6dB volume (with respect to peak positive pressure) from 1.6 to 0.4cm3, the −6dB volume (with respect to peak negative pressure) from 14.5 to 8.3cm3, and reduced the volume characterized by high cavitation potential (i.e., regions characterized by bubbles with radii larger than 429μm) from 103 to 26cm3. Thus, the insert is an effective way to localize the potentially damaging effects of shock wave lithotripsy, and suggests an approach to optimize the shape of the reflector.
Structural, microstructural, and transport properties of highly oriented LaNiO3 thin films deposited on SrTiO3 (100) single crystal
Authors: Mambrini G. P. , Leite E. R. , Escote M. T. , Chiquito A. J. , Longo E. , Varela J. A. , Jardim R. F.
Published: August 2007

Electrical conductive textured LaNiO3/SrTiO3 (100) thin films were successfully produced by the polymeric precursor method. A comparison between features of these films of LaNiO3 (LNO) when heat treated in a conventional furnace (CF) and in a domestic microwave (MW) oven is presented. The x-ray diffraction data indicated good crystallinity and a structural orientation along the (h00) direction for both films. The surface images obtained by atomic force microscopy revealed similar roughness values, whereas films LNO-MW present slightly smaller average grain size (∼80 nm) than those observed for LNO-CF (60–150 nm). These grain size values were in good agreement with those evaluated from the x-ray data. The transport properties have been studied by temperature dependence of the electrical resistivity ρ(T) which revealed for both films a metallic behavior in the entire temperature range studied. The behavior of ρ(T) was investigated, allowing to a discussion of the transport mechanisms in these films.
Effect of growth temperature on defect states of GaAsSbN intrinsic layer in GaAs∕GaAsSbN∕GaAs photodiode for 1.3μm application
Authors: Wicaksono S. , Yoon S. F. , Loke W. K. , Tan K. H. , Lew K. L. , Zegaoui M. , Vilcot J. P. , Decoster D. , Chazelas J.
Published: August 2007

A GaAsSbN layer closely lattice matched to GaAs was used as an intrinsic layer (i layer) in a GaAs∕GaAsSbN∕GaAs p-i-n photodiode with response up to 1.3μm. Deep level transient spectroscopy measurement on the GaAs∕GaAsSbN∕GaAs reveals two types of hole traps (HTs) in the GaAsSbN i layer; (i) HT1: a shallow N-related defect state (Ea∼0.10–0.12eV) and (ii) HT2: an AsGa point defect-related midgap defect state with Ea∼0.42–0.43eV. Reduction in growth temperature from 480to420°C reduces the HT2 trap concentration from 4×1015to1×1015cm−3, while increases the HT1 trap concentration from 1×1014to7×1014cm−3. Reduction in the HT2 trap concentration following growth temperature reduction was attributed to the suppression of AsGa point defect formation. Evidence of possible change of the AsGa midgap state to a shallow level defect due to the formation of (AsGa–NAs) pairs was also suggested to have increased the HT1 trap concentration and reduced the HT2 trap concentration. An ∼4dBm improvement in photoresponse under 1.3μm laser excitation and approximately eight times reduction in dark current at −8V reverse bias were attributed to the reduction in the overall trap concentration and mainly the reduction of the AsGa-related midgap trap concentration in the sample grown at 420°C.
Forward current-voltage characteristics of an AlGaInP light-emitting diode
Authors: Chen N. C. , Yang Y. K. , Lien W. C. , Tseng C. Y.
Published: August 2007

This work discusses the temperature-dependent forward current-voltage characteristics of an AlGaInP light-emitting diode. From 300 to 470 K, all curves have the same ideality factor of n=1.58. The temperature-dependent saturation currents are in excellent agreement with the thermal activation behavior over ten decades of current and with an activation energy of Ea=1.405 eV. Based on the discussion of the barrier for forward current flow, nEa corresponds to the band gap of the active layer. Various mechanisms of current flow for pn junctions and Schottky diodes were examined and verified. Therefore, the nEa=2.22 eV of the sample corresponds to the band gap of the barriers in the active layer. This value is consistent with the band gap of (AlxGa1−x)0.5In0.5P for x>0.58.
Polarity inversion in high Mg-doped In-polar InN epitaxial layers
Authors: Wang Xinqiang , Che Song-Bek , Ishitani Yoshihiro , Yoshikawa Akihiko , Sasaki Hirokazu , Shinagawa Tatsuyuki , Yoshida Seikoh
Published: August 2007

To investigate the Mg-dopability in In-polar InN epilayers grown by molecular beam epitaxy, polarity inversion dependence on Mg-doping level is studied. A multiple-InN layer-structure sample with different Mg-doping levels is grown and analyzed by transmission electron microscopy. Formation of high density V-shaped inversion domains is observed for the Mg-doped InN with Mg concentration ([Mg]) of 2.9×1019cm−3. These domains lead to polarity inversion from In to N polarity. Further study for Mg-doped InN epilayers shows that polarity inversion takes place when [Mg] increases above 1.6×1019cm−3. It is also shown that the Mg-sticking coefficient is almost independent of the polarity.
Relationship between host energy levels and device performances of phosphorescent organic light-emitting diodes with triplet mixed host emitting structure
Authors: Kim Sung Hyun , Jang Jyongsik , Lee Jun Yeob
Published: August 2007

Green phosphorescent organic light-emitting diodes (PHOLEDs) with a triplet mixed host emitting layer were developed and device performances were studied by changing host materials in light-emitting layer. Power efficiency of green PHOLEDs could be improved from 12.7to29.1lm∕W by using triplet mixed host emitting layer. Combination of hole-transport-type host with good hole injection properties and electron-transport-type host with good electron injection properties was effective to get high efficiency in triplet mixed host devices.
Rich-club phenomenon across complex network hierarchies
Authors: McAuley Julian J. , da Fontoura Costa Luciano , Caetano Tibério S.
Published: August 2007

The “rich-club phenomenon” in complex networks is characterized when nodes of higher degree are more interconnected than nodes with lower degree. The presence of this phenomenon may indicate several interesting high-level network properties, such as tolerance to hub failures. Here, the authors investigate the existence of this phenomenon across the hierarchies of several real-world networks. Their simulations reveal that the presence or absence of this phenomenon in a network does not imply its presence or absence in the network’s successive hierarchies, and that this behavior is even nonmonotonic in some cases.
Novel method for characterizing relativistic electron beams in a harsh laser-plasma environment
Authors: Hidding B. , Pretzler G. , Clever M. , Brandl F. , Zamponi F. , Lübcke A. , Kämpfer T. , Uschmann I. , Förster E. , Schramm U. , Sauerbrey R. , Kroupp E. , Veisz L. , Schmid K. , Benavides S. , Karsch S.
Published: August 2007

Particle pulses generated by laser-plasma interaction are characterized by ultrashort duration, high particle density, and sometimes a very strong accompanying electromagnetic pulse (EMP). Therefore, beam diagnostics different from those known from classical particle accelerators such as synchrotrons or linacs are required. Easy to use single-shot techniques are favored, which must be insensitive towards the EMP and associated stray light of all frequencies, taking into account the comparably low repetition rates and which, at the same time, allow for usage in very space-limited environments. Various measurement techniques are discussed here, and a space-saving method to determine several important properties of laser-generated electron bunches simultaneously is presented. The method is based on experimental results of electron-sensitive imaging plate stacks and combines these with Monte Carlo-type ray-tracing calculations, yielding a comprehensive picture of the properties of particle beams. The total charge, the energy spectrum, and the divergence can be derived simultaneously for a single bunch.
A
Drosophila
gustatory receptor required for the responses to sucrose, glucose, and maltose identified by mRNA tagging
Authors: Jiao Yuchen , Moon Seok Jun , Montell Craig
Published: August 2007

In
Drosophila
, detection of tastants is thought to be mediated by members of a family of 68 gustatory receptors (Grs). However, only one receptor, Gr5a, has been associated with a sugar, and it appears to be activated specifically by trehalose. It is unclear whether other sugar receptors are activated by single or multiple sugars. Currently, no Grs are known to colocalize with Gr5a. Such Grs would be candidate sugar receptors because Gr5a-expressing cells function in the responses to attractive tastants. Here we use an “mRNA tagging” approach to identify
Gr
RNAs that are coexpressed with
Gr5a
. We found that all seven
Gr
s most related to
Gr5a
(
Gr64a-f
and
Gr61a
) were expressed in
Gr5a
-expressing cells, whereas none of the other
Gr
s examined were enriched in these Gr neurons (GRNs). We characterized the role of one Gr5a-related receptor, Gr64a, and found that it was required for the behavioral responses to glucose, sucrose, and maltose.
Gr64a
was required for GRN function because action potentials induced by these sugars were dependent on expression of
Gr64a
in GRNs. These data demonstrate that multiple Grs are coexpressed with Gr5a and that
Drosophila
Gr64a is required for the responses to multiple sugars.
Metabolic engineering of a genetic selection system with tunable stringency
Authors: Kleeb Andreas C. , Edalat Maryam Hansson , Gamper Marianne , Haugstetter Johannes , Giger Lars , Neuenschwander Martin , Kast Peter , Hilvert Donald
Published: August 2007

The biosynthesis of small molecules can be fine-tuned by (re)engineering metabolic flux within cells. We have adapted this approach to optimize an
in vivo
selection system for the conversion of prephenate to phenylpyruvate, a key step in the production of the essential aromatic amino acid phenylalanine. Careful control of prephenate concentration in a bacterial host lacking prephenate dehydratase, achieved through provision of a regulable enzyme that diverts it down a parallel biosynthetic pathway, provides the means to systematically increase selection pressure on replacements of the missing catalyst. Successful differentiation of dehydratases whose activities vary over a >50,000-fold range and the isolation of mechanistically informative prephenate dehydratase variants from large protein libraries illustrate the potential of the engineered selection strain for characterizing and evolving enzymes. Our approach complements other common methods for adjusting selection pressure and should be generally applicable to any selection system that is based on the conversion of an endogenous metabolite.
Oxidation of the sugar moiety of DNA by ionizing radiation or bleomycin could induce the formation of a cluster DNA lesion
Authors: Regulus Peggy , Duroux Benoit , Bayle Pierre-Alain , Favier Alain , Cadet Jean , Ravanat Jean-Luc
Published: August 2007

Bleomycin, a radiomimetic drug currently used in human cancer therapy, is a well known carcinogen. Its toxicity is mostly attributed to its potentiality to induce DNA double strand breaks likely arising from the formation of two vicinal DNA strand breaks, initiated by C4-hydrogen abstraction on the 2-deoxyribose moiety. In this work we demonstrate that such a hydrogen abstraction reaction is able to induce the formation of a clustered DNA lesion, involving a 3′ strand break together with a modified sugar residue exhibiting a reactive α,β-unsaturated aldehyde that further reacts with a proximate cytosine base. The lesion thus produced was detected as a mixture of four isomers by HPLC coupled to tandem mass spectrometry subsequent to DNA extraction and enzymatic digestion. The modified nucleosides that constitute new types of cytosine adducts were identified as the likely two pairs of diastereomers of 6-(2-deoxy-β-
d
-
erythro
-pentofuranosyl)-2-hydroxy-3(3-hydroxy-2-oxopropyl)-2,6-dihydroimidazo[1,2-c]-pyrimidin-5(3
H
)-one as inferred from mass spectrometry and NMR analyses of the chemically synthesized nucleosides. We demonstrate that bleomycin, and to a minor extent ionizing radiation, are able to induce significant amounts of the cytosine damage in cellular DNA. In addition, the repair kinetic of the lesion in a human lymphocyte cell line is rather slow, with a half-life of 10 h. The 2′-deoxycytidine adducts thus characterized that represent the first example of complex DNA lesions isolated and identified in cellular DNA upon one radical hit are likely to play an important role in the toxicity of bleomycin.
An 11-amino acid β-hairpin loop in the cytoplasmic domain of band 3 is responsible for ankyrin binding in mouse erythrocytes
Authors: Stefanovic Marko , Markham Nicholas O. , Parry Erin M. , Garrett-Beal Lisa J. , Cline Amanda P. , Gallagher Patrick G. , Low Philip S. , Bodine David M.
Published: August 2007

The best-studied cytoskeletal system is the inner surface of the erythrocyte membrane, which provides an erythrocyte with the structural support needed to be stable yet flexible as it passes through the circulation. Current structural models predict that the spectrin–actin-based cytoskeletal network is attached to the plasma membrane through interactions of the protein ankyrin, which binds to both spectrin and the cytoplasmic domain of the transmembrane protein band 3. The crystal structure of the cytoplasmic domain of band 3 predicted that the ankyrin binding site was located on a β-hairpin loop in the cytoplasmic domain.
In vitro
, deletion of this loop eliminated ankyrin affinity for band 3 without affecting any other protein–band 3 interaction. To evaluate the importance of the ankyrin–band 3 linkage to membrane properties
in vivo
, we generated mice with the nucleotides encoding the 11-aa β-hairpin loop in the mouse
Slc4a1
gene replaced with sequence encoding a diglycine bridge. Mice homozygous for the loop deletion were viable with mildly spherocytic and osmotically fragile erythrocytes.
In vitro
, homozygous
ld
/
ld
erythrocytes were incapable of binding ankyrin, but contrary to all previous predictions, abolishing the ankyrin–band 3 linkage destabilized the erythrocyte membrane to a lesser degree than complete deficiencies of either band 3 or ankyrin. Our data indicate that as yet uncharacterized interactions between other membrane proteins must significantly contribute to linkage of the spectrin–actin-based membrane cytoskeleton to the plasma membrane.
Comparing Phonation Threshold Flow and Pressure by Abducting Excised Larynges
Authors: Hottinger Daniel G. , Tao Chao , Jiang Jack J.
Published: August 2007

Objectives/Hypothesis: This experiment studied a new aerodynamic parameter, phonation threshold flow, along with phonation threshold pressure, by varying prephonatory glottal width in canine larynges ex vivo. Goals were to examine phonation threshold flow as a measurable parameter sensitive to physiologic changes in the vocal folds and compare the relative sensitivities of phonation threshold flow and phonation threshold pressure.

Methods: Ten excised canine larynges were tested on a bench apparatus for subglottal pressure and airflow at phonation onset. Metal shims simulated abduction levels ranging from 0.0 to 4.0 mm. For each glottal configuration, airflow through the larynx was increased until the vocal folds began vibrating, and onset airflow and pressures were recorded.

Results: One‐way analysis of variance (ANOVA) found significant differences in the aggregate phonation threshold flow means over the latter portion of the width domain (1.0–4.0 mm). Phonation threshold flow increased as posterior glottal width increased and was modeled linearly. One‐way ANOVA of phonation threshold pressure means was insignificant, with a P value of .941.

Conclusion: Results showed phonation threshold flow to be more sensitive to posterior glottal width changes than phonation threshold pressure. Therefore, phonation threshold flow could be a more effective indicator than phonation threshold pressure for those vocal diseases related to abduction.
Dry dermoscopy in clinical treatment of alopecia areata
Authors: INUI Shigeki , NAKAJIMA Takeshi , ITAMI Satoshi
Published: August 2007

Although dermoscopy is conventionally utilized with immersion gel for diagnosis of pigmented tumor, we utilized dry dermoscopy, which is dermoscopy without immersion gel, for clinical treatment of alopecia areata (AA). The scalp skin and hair of a 38‐year‐old Japanese male, and 23‐, 22‐ and 47‐year‐old Japanese females with AA, whose normal hair color was black, were examined by dry dermoscopy. Exclamation mark hairs, short hairs, fractured hairs and black dots, all characteristic of AA, were detected by dry dermoscopy of the scalp of the 23‐year‐old female with ophiasis type AA. In the case of the 47‐year‐old female with round hair loss on the occipital scalp and diffuse hair loss over the fronto‐vertical region, dry dermoscopy was useful for diagnosis of AA based on hair characteristic of AA. After she received corticosteroid pulse therapy with 500 mg of i.v. methylprednisolone on 3 successive days, her hair showed apparent regrowth and disappearance of the abnormal hairs characteristic of AA, evidenced by dry dermoscopy 1 month later. In a case of long‐lasting AA in the 23‐year‐old female, we found a follicular plaque‐like appearance at the opened hair follicle pores by dry dermoscopy. Histopathologically, the incompletely differentiated remnant hair shaft was packed in the follicular infundibulum. In addition, regrowing vellus hairs, which were difficult to clinically recognize, were detected by dry dermoscopy. Dry dermoscopy is therefore useful for both diagnosis and follow up of AA.
Flow‐field observations of a tidally driven island wake used by marine mammals in the Bay of Fundy, Canada
Authors: JOHNSTON D. W. , READ A. J.
Published: August 2007

Correlations between fine‐scale oceanographic features and aggregations of marine mammals are frequently reported, but the physical forces shaping these relationships are rarely explored. We conducted a series of oceanographic observations and remote sensing surveys of an oceanographic feature near Grand Manan Island known to attract marine mammals on flood tides. We tracked drift drogues from cliff‐top with a theodolite and conducted box‐type surveys with an acoustic Doppler current profiler (ADCP) to assess flow patterns within the oceanographic feature. The feature was also visualized with Synthetic Aperture Radar (SAR) scenes. Drift drogues were advected towards a shear line originating near the northern tip of the island and entrained in one or more eddies downstream. ADCP surveys confirmed the presence of the shear line between rapid easterly flow and slower return flow. As the tide progressed, the shear line extended and manifested a single anti‐cyclonic eddy at its distal end. As the flood tide progressed, northerly flow along the eastern shore of the island intensified and deflected the shear line northwards, shedding the eddy at slack high water. SAR images confirmed the presence of the shearline and eddy system, illustrating the evolution of a wake behind the island on flood tides. Profiles of flow direction and acoustic backscatter revealed secondary flows within the wake consistent with models and observations of other wakes. Oceanographic and remote sensing observations confirm that an island wake is generated by tidal flow past Grand Manan Island and provide an ecological context for the predictable aggregations of odontocete and mysticete cetaceans observed foraging within this region.
Rethinking the interface between ecology and society. The case of the cockle controversy in the Dutch Wadden Sea
Authors: Swart Jac. A. A , Van Andel Jelte
Published: August 2007

Applied ecology, like conservation research, may deal with societal issues if its scientifically based interventions have societal consequences. Human utilization plays a significant role in many ecosystems, so conservation ecologists often have to act on the interface between science and society, where controversies may arise.

Using insights from science and technology studies, we have analysed the 15‐year controversy on the ecological effects of cockle fishing in the Dutch Wadden Sea, which began around 1990 and involved nature protection and shellfish organizations, as well as several leading Dutch ecologists, in a heated debate.

During this controversy, evaluative research on the ecological effects of cockle fishing was undertaken by a consortium of institutes in order to contribute to the process of political decision‐making by the Dutch government on cockle fishery in this area. In addition to conservational and commercial interests, ecological research itself became part of the controversy.

The research projects on the effects of cockle fishing during this controversy are examples of societally contextualized science, implying that interests and societal disputes are intertwined with scientific arguments. We have applied a dynamic model of contextualization in which societal stakes and scientific uncertainty are considered as the main factors determining the different contexts in which conservation research functions.

Synthesis and applications. Conservation research, whether it is fundamental or managerially orientated, is related to greater societal aims and interests and might easily face more or less complex societally contextualized situations. Such situations imply extended responsibilities for scientists. Not only is there a need for sound science, but also for a sound way of interacting and communicating with the societal environment. Some elements of such a notion of extended accountability are presented.
Being family: the family experience when an adult member is hospitalized with a critical illness
Authors: Eggenberger Sandra K , Nelms Tommie P
Published: August 2007

Aims and objectives. The purpose of this qualitative study was to understand and interpret the ‘family experience’ with an adult member hospitalized with a critical illness.

Background. Nursing practice in critical care settings has traditionally focused on individual patient needs with only tangential recognition of family needs. Investigation to describe the family experience to illuminate family nursing practice has been lacking. The majority of studies thus far related to critical illness and family are quantitative and reveal constraints to family care and problematic nurse–family interactions. The logical next step is a new kind of family research to enhance nursing of the family as a whole.

Design. Family systems theory and existential phenomenology provided the frameworks guiding the study.

Methods. Semi‐structured ‘family as a group’ interviews were performed with 11 families. Data were analysed using Van Manen's hermeneutic method. Rigor was addressed with trustworthiness criteria.

Results. The family experience was analysed within Van Manen's framework of lived space, lived relation, lived body and lived time. A constitutive pattern of being family was revealed.

Conclusions. Being family bonds families and makes them exceedingly strong during the critical illness experience. Being a family unit is what gives most families the ability to endure the emotional upheaval and suffering that come with the critical illness experience.

Relevance to clinical practice. Nurses have profound power to help families bear this experience. Family caring is enhanced with the presence of nurses who recognize the importance of ‘Being Family’ for the family, acknowledge the significance of the nurse–family relationship and act on a commitment to bewithandforthe family.
Depressive symptoms among older residents at nursing homes in Taiwan
Authors: Lin Pao‐Chen , Wang Hsiu‐Hung , Huang Hui‐Tzu
Published: August 2007

Aims and objectives.  To examine the depressive symptoms of older residents at nursing homes and the relationship between their depressive symptoms and certain selected variables.

Background.  Depression has become a major healthcare concern among the older people, but nursing home‐based studies on risk factors of depression have still hardly been well performed in Taiwan.

Design.  A cross‐sectional design was developed and implemented.

Methods.  A research sample of 138 older residents was recruited from eight nursing homes located in southern Taiwan. During face‐to‐face interviews, the Center for Epidemiological Studies Depression Scale, Social Support Scale, Chronic Condition Checklist and Socio‐demographic Inventory were used for data collection.

Results.  The results showed that 81·8% of those residents were identified as being depressed. It was further discovered that the length of residency, number of chronic conditions, perceived health status and the amount of social support from their family and relatives could explain 38·8% of the total variances in depressive symptoms.

Conclusions.  Our study suggests that, in Taiwan, older people who live in nursing homes suffer from more depressive symptoms than those in community dwellings. To maintain and improve the health status for the elderly as much as possible, it is suggested that healthcare providers at nursing homes should develop an effective health promotion program for these older peoples.

Relevance to clinical practice.  There exists a high rate of depressive symptoms among older residents at nursing homes. It is imperative that a proper identification and its correspondent treatment for this health problem on the older residents are required. In late life, to maintain a higher level of quality of life, it is important to suggest that the health providers should regularly screen older people to increase the likelihood of diagnosis and improved treatment of late‐life depressive symptoms.