bluuebunny/crossref_metadata_2025 huggingface dataset:
Determination of the stiffness of cellulose nanowhiskers and the fiber-matrix interface in a nanocomposite using Raman spectroscopy
Authors: Rusli Rafeadah , Eichhorn Stephen J.
Published: July 2008

The stiffness of 10 nm diameter cellulose nanowhiskers is reported. These whiskers are produced by acid hydrolysis. These whiskers are dispersed in epoxy resin and placed on the surface of a beam of the same material and deformed in tension and compression using a four-point bending device. By following the molecular deformation of the whiskers using Raman spectroscopy it is shown that, by theoretical models of their dispersion and matrix reinforcement, their stiffness can be derived. The effects of debonding, matrix yielding, and buckling of whiskers are also discussed using this method as a means for studying nanocomposite materials.
Strong terahertz conductance of graphene nanoribbons under a magnetic field
Authors: Liu Junfeng , Wright A. R. , Zhang Chao , Ma Zhongshui
Published: July 2008

We demonstrate that the optical response of graphene nanoribbons in the terahertz to far-infrared regime can be significantly enhanced and tuned by an applied magnetic field. The dependence of the threshold frequency on the magnetic field is studied. The ribbons with the strongest terahertz conductance under a magnetic field are those with one-dimensional massless Dirac Fermion energy dispersion. For a given ribbon, there exists an optimal field under which the conductance resonance can occur at the lowest frequency.
Remote detection of human electrophysiological signals using electric potential sensors
Authors: Prance R. J. , Beardsmore-Rust S. T. , Watson P. , Harland C. J. , Prance H.
Published: July 2008

We describe the measurement of human electrophysiological and movement signals remotely from a seated subject. An ultrahigh impedance electric potential sensor, designed specifically to reject external noise, is used to measure the electric field at distances of up to 40cm from the surface of the body. The sensor is able to provide continuous data acquisition, at full sensitivity, without saturation by external noise sources. Respiration and heart signals are seen simultaneously and are separated using digital filtering techniques. All of the results reported were obtained in an open unshielded environment in close proximity to line operated computer equipment.
Collimated GeV electrons from the ionization of a gas by a laser pulse in an intense magnetic field
Authors: Singh Kunwar Pal , Malik Hitendra K.
Published: July 2008

A scheme is proposed for the acceleration of electrons generated during ionization of the helium and nitrogen gases by a laser pulse in the presence of an intense magnetic field. The electrons generated from the low atomic number gases gain energy in GeV due to the resonance between the electrons and the electric field of the laser in the presence of magnetic field. It is shown that collimated GeV electrons with small energy spread can be obtained from the ionization of helium and nitrogen. Suitable parameters have also been found for the suggested scheme.
Ion bombardment effects on ZnO nanowires during plasma treatment
Authors: Ra H.-W. , Choi K. S. , Ok C. W. , Jo S. Y. , Bai K. H. , Im Y. H.
Published: July 2008

We present the effects of ion bombardment on ZnO nanowires caused by their exposure to an Ar inductively coupled plasma. The conductivity of the individual ZnO nanowire was increased in up to 3 orders of magnitude due to increase in both carrier concentration and mobility, with a substantial negative shift in the threshold gate voltage also being observed. The drastic changes in the electrical properties were attributed to the decrease in species adsorbed on the surface, as well as to the increase in oxygen vacancies near the surface caused by ion bombardment.
A study of the pair distribution function of self-organized Ge quantum dots
Authors: Bernardi Marco , Sgarlata Anna , Fanfoni Massimo , Balzarotti Adalberto , Motta Nunzio
Published: July 2008

We explore the use of the pair distribution function to study the self-organization process of Ge quantum dots on both nanopatterned and nonpatterned oxidized Si(001) surfaces. Dots formation and ordering upon annealing of a Ge thin film are analyzed. The method we use is not limited to this case study. We show how it can be applied to determine short and long range self-ordering of nanostructures. We support our results by applying a software routine to simulate patterns of dots to finally spot the relevant physical aspects of Ge islands self-assembly.
A pure 1.5 μm electroluminescence from metal-oxide-silicon tunneling diode using dislocation network
Authors: Yu X. , Seifert W. , Vyvenko O. F. , Kittler M. , Wilhelm T. , Reiche M.
Published: July 2008

This letter has demonstrated a light emitting diode (LED) with a pure 1.5 μm emission using a metal-oxide-silicon (MOS) tunneling structure based on dislocation network in direct silicon bond wafer. It is found that under negative gate bias, the electrons in the metal gate electrode tunnel through the thin oxide to silicon and then recombine radiatively with holes at the dislocation related states to emit the D1-line with a wavelength of 1.5 μm. The calculation of energy band diagram indicates that a potential well for electrons forms at the charged bonding interface under negative bias, therefore, the electrons tunneled from the gate can rapidly be attracted by the electric field and then confined at the interface, which essentially increases the efficiency of D1 luminescence from MOS tunneling LED. These results are of interest for the development of silicon based photonics with 1.5 μm light emission.
Photovoltaic cells fabricated by electrophoretic deposition of CdSe nanocrystals
Authors: Smith Nathanael J. , Emmett Kevin J. , Rosenthal Sandra J.
Published: July 2008

Electrophoretic deposition was used to deposit CdSe nanocrystals on TiO2 for use in photovoltaic cells. The deposition current underwent a simple exponential decay, consistent with the current being comprised of charge transfer from charged nanocrystals to the electrodes. Rutherford backscattering spectroscopy showed the composition of the deposited films depended on the polarity of the electrode on which the film formed. A solar cell constructed using electrophoretic deposition exhibited a photovoltaic response from the region in which nanocrystals were deposited, with an efficiency of ∼10−6%. The low efficiency was primarily due to the planar geometry employed for the TiO2 subsrate.
Bilinear responses and rippling morphologies of multiwalled carbon nanotubes under torsion
Authors: Huang Xu , Zou Jian , Zhang Sulin
Published: July 2008

We present coarse-grained simulations of torsion induced rippling deformation morphology of multiwalled carbon nanotubes (MWCNTs). Our simulations reveal that beyond the torsional bifurcation, the rippling pattern propagates from outer to inner layers, with the two innermost layers acting as a hard core that hardly ripples. Despite the highly nonlinear rippling deformation, the mechanical response of MWCNTs follows a simple bilinear law, with a nearly constant ratio (∼60%) of post- to prerippling torsional rigidities. The bifurcation torsion scales inversely with the square of tube radius. This bilinear constitutive relation may be exploited by large-scale simulations of MWCNT-based materials and devices.
Unusual transport characteristics of nitrogen-doped single-walled carbon nanotubes
Authors: Min Yo-Sep , Bae Eun Ju , Kim Un Jeong , Lee Eun Hong , Park Noejung , Hwang Cheol Seong , Park Wanjun
Published: July 2008

Electrical transport characteristics of nitrogen-doped single-walled carbon nanotubes (N-SWCNTs), in which the nitrogen dopant is believed to form a pyridinelike bonding configuration, are studied with the field effect transistor operations. Contrary to the expectation that the nitrogen atoms may induce a n-type doping, the electrical transports through our N-SWCNTs are either ambipolar in vacuum or p-type in air. Through the first-principles electronic structure calculations, we show that the nitrogen dopant indeed favors the pyridinelike configuration and the Fermi level of the pyridinelike N-SWCNT is almost at the intrinsic level.
Enhanced optical responsivity of InAlAs∕InGaAs metamorphic high mobility electron mobility using indium tin oxide transparent gate technology
Authors: Chiu Hsien-Chin , Lin Che-Kai , Lin Chao-Wei , Chen Ming-Yang
Published: July 2008

The high optical responsivity of a transparent gate metamorphic high electron mobility transistor (TG-MHEMT) on GaAs substrate is demonstrated. The transmittance of a 1.3μm emission wavelength for sputtered indium tin oxide TG-MHEMT gate fingers was 90% after 2min of annealing at 300°C and the sheet resistance was 31.3Ωmm. Compared to the back side illumination of a MHEMT phototransistor, which is beneficial for improving photoresponse, the TG-MHEMT can avoid the inconvenient back side thin-down and polish processes. Experimental results demonstrate that TG-MHEMT has good optical performance at a wavelength of λ=1.3μm and comparable to that of the conventional metal gate MHEMT. The increase in drain current and decrease in threshold voltage caused by the illumination can be explained by the photovoltaic effect beneath the transparent gate. The responsivity of TG-MHEMT is roughly 20.6A∕W for a wavelength of λ=1.3μm.
Broadband electro-optic polymer modulators with high electro-optic activity and low poling induced optical loss
Authors: Chen H. , Chen B. , Huang D. , Jin D. , Luo J. D. , Jen A. K.-Y. , Dinu R.
Published: July 2008

A screening method is reported for electro-optic (EO) polymers with an emphasis on broadband device suitability. The method is based on comparing the signal from second harmonic generation (SHG) and the leak through current (LTC) during poling. Plots of the SHG and LTC are used to define high EO activity-low current poling windows that are critical for low driving voltage, broadband devices with relatively low optical loss. The screening procedure was used to select an EO polymer core that resulted in a 40Gbits∕s broadband modulator with a driving voltage of 1.3V and an insertion loss of <8dB.
Direct observation of oxygen movement during resistance switching in NiO/Pt film
Authors: Yoshida Chikako , Kinoshita Kentaro , Yamasaki Takahiro , Sugiyama Yoshihiro
Published: July 2008

We demonstrate that both a low resistance state and a high resistance state can be written by bipolar voltage application in a local region of NiO/Pt films by using conducting atomic force microscopy. To investigate how oxygen played a role in the resistance switching phenomenon, a local writing process in O18 tracer gas atmosphere was carried out and the composition change was examined by time-of-flight secondary ion mass spectroscopy. As a result, it was revealed that oxygen moves to the anode side, and the composition of the NiO surface might change thereby causing the change in resistance.
Impact of resistance on cathodoluminescence and its application for layer sheet-resistance measurements
Authors: Czerwinski A. , Pluska M. , Ratajczak J. , Szerling A. , Kątcki J.
Published: July 2008

The dependence of cathodoluminescence (CL) on resistances in semiconductor structures, especially on layer resistances, is described. The effect can be taken advantage of and used for characterization of sheet resistance of thin layers in semiconductor devices, as illustrated in this paper by an assessment of lateral confinements in semiconductor-laser heterostructures. At the same time, the effect, if neglected, can be detrimental for accuracy of spatially or spectrally resolved CL studies.
Abstract: Linear electric field shift of a ferromagnetic resonance: Lithium ferrite
Authors: Rado G. T. , Vittoria C. , Ferrari J. M. , Remeika J. P.
Published: July 2008

Using circular disks cut from the ’’skin’’ region of ionically ordered Li0.5Fe2.5O4, we now report the first observation and interpretation of linear E-shifts of a ferromagnetic resonance. (AIP)
Interannual variations of above-ground biomass and nutritional quality of Mediterranean grasslands in Western Spain over a 20-year period
Authors: Vázquez-de-Aldana B. R. , García-Ciudad A. , García-Criado B.
Published: July 2008

The ‘dehesas’ are savannah-like semi-arid grasslands typical of western Spain, which are subject to strong inter-annual variations in biomass production. Over a 20-year period, from 1986 to 2005, above-ground biomass and the nutritional quality of these grasslands in the province of Salamanca (western Spain) were evaluated to determine the relationships between interannual variations in grassland parameters and climate variables (precipitation and temperature). Herbage samples were collected from several sites, along a topographic gradient that differentiated two types of herbaceous communities on the upper and lower part of the slope. Nutritional quality was assessed on the basis of protein, acid detergent fibre, neutral detergent fibre, lignin and digestibility. On both the upper and lower zones, total biomass and biomass of grasses were correlated with annual precipitation calculated from the previous October to the current June. Biomass of legumes and forbs, on the upper zones, was correlated with spring precipitation. Step-wise multiple regression analysis provided different models for grasses, legumes, forbs, and total biomass for the upper and lower zones. Protein concentration was negatively correlated with annual precipitation in both zones of the slope. The number of days in spring with precipitation (≥1 mm or ≥10 mm) was a good predictor of the lignin content and digestibility in both zones of the slope, and of the acid detergent fibre content on the upper zones and the neutral detergent fibre content on the lower zones.
Simulating pasture growth rates in Australian and New Zealand grazing systems
Authors: Cullen B. R. , Eckard R. J. , Callow M. N. , Johnson I. R. , Chapman D. F. , Rawnsley R. P. , Garcia S. C. , White T. , Snow V. O.
Published: July 2008

DairyMod, EcoMod, and the SGS Pasture Model are mechanistic biophysical models developed to explore scenarios in grazing systems. The aim of this manuscript was to test the ability of the models to simulate net herbage accumulation rates of ryegrass-based pastures across a range of environments and pasture management systems in Australia and New Zealand. Measured monthly net herbage accumulation rate and accumulated yield data were collated from ten grazing system experiments at eight sites ranging from cool temperate to subtropical environments. The local climate, soil, pasture species, and management (N fertiliser, irrigation, and grazing or cutting pattern) were described in the model for each site, and net herbage accumulation rates modelled. The model adequately simulated the monthly net herbage accumulation rates across the range of environments, based on the summary statistics and observed patterns of seasonal growth, particularly when the variability in measured herbage accumulation rates was taken into account. Agreement between modelled and observed growth rates was more accurate and precise in temperate than in subtropical environments, and in winter and summer than in autumn and spring. Similarly, agreement between predicted and observed accumulated yields was more accurate than monthly net herbage accumulation. Different temperature parameters were used to describe the growth of perennial ryegrass cultivars and annual ryegrass; these differences were in line with observed growth patterns and breeding objectives. Results are discussed in the context of the difficulties in measuring pasture growth rates and model limitations.
Ecogeography of the Old World lupins. 1. Ecotypic variation in yellow lupin (Lupinus luteus L.)
Authors: Berger J. D. , Adhikari K. N. , Wilkinson D. , Buirchell B. J. , Sweetingham M. W.
Published: July 2008

Agricultural crops and their wild progenitors are excellent candidates for ecophysiologal research because germplasm collections are often extensive and well described, and in its dissemination the crop may explore new habitats. The advent of high-resolution climate models has greatly improved our capacity to characterise plant habitats, and study species’ adaptive responses. The yellow lupin (Lupinus luteus) is ideal because it evolved as a Mediterranean winter-annual in relatively high-rainfall coastal regions, but was domesticated as a summer crop in temperate central Europe. Currently the crop is being developed for Mediterranean south-western Australia, raising an interesting ecophysiological problem: is it more appropriate to concentrate on wild material from Mediterranean habitats, which are likely to be more similar to the target environments, or on European germplasm domesticated for temperate summer cropping? Lupinus luteus collection sites across the natural and domesticated distribution range were characterised by calculating site-specific bioclimatic variables and habitat types defined using multivariate analysis. Germplasm was evaluated in 2 field trials measuring a range of characters describing plant growth, phenology, architecture, and productivity. The earliest phenology and highest vigour and productivity were recorded in domesticated material from central Europe, characterised by short but unstressful growing seasons with reliable rainfall, long day-lengths, and rapidly rising vegetative-phase temperatures levelling out after flowering. Mediterranean habitats were classified by altitude, climate, and growing-season length. Early, productive germplasm came from warmer/low elevation sites with inconsistent rainfall and stronger terminal drought. Germplasm from low temperature/high elevation sites with high, relatively frequent rainfall had late phenology and low growth rates, early vigour, seed yield, and harvest index. Distinct habitats within the distribution range of L. luteus have selected for ecotypes with different phenologies and growth rates, which strongly influence plant architecture, fecundity and yield. It is suggested that variable responses to vernalisation and differences in seed size are important in determining these traits. European germplasm has many of the terminal drought-avoiding characteristics required in a productive Mediterranean ideotype, but may lack drought tolerance, which is likely to be under stronger selection pressure in more stressful Mediterranean habitats.
Poorly cemented coral reefs of the eastern tropical Pacific: Possible insights into reef development in a high-CO
2
world
Authors: Manzello Derek P. , Kleypas Joan A. , Budd David A. , Eakin C. Mark , Glynn Peter W. , Langdon Chris
Published: July 2008

Ocean acidification describes the progressive, global reduction in seawater pH that is currently underway because of the accelerating oceanic uptake of atmospheric CO
2
. Acidification is expected to reduce coral reef calcification and increase reef dissolution. Inorganic cementation in reefs describes the precipitation of CaCO
3
that acts to bind framework components and occlude porosity. Little is known about the effects of ocean acidification on reef cementation and whether changes in cementation rates will affect reef resistance to erosion. Coral reefs of the eastern tropical Pacific (ETP) are poorly developed and subject to rapid bioerosion. Upwelling processes mix cool, subthermocline waters with elevated pCO
2
(the partial pressure of CO
2
) and nutrients into the surface layers throughout the ETP. Concerns about ocean acidification have led to the suggestion that this region of naturally low pH waters may serve as a model of coral reef development in a high-CO
2
world. We analyzed seawater chemistry and reef framework samples from multiple reef sites in the ETP and found that a low carbonate saturation state (Ω) and trace abundances of cement are characteristic of these reefs. These low cement abundances may be a factor in the high bioerosion rates previously reported for ETP reefs, although elevated nutrients in upwelled waters may also be limiting cementation and/or stimulating bioerosion. ETP reefs represent a real-world example of coral reef growth in low-Ω waters that provide insights into how the biological–geological interface of coral reef ecosystems will change in a high-CO
2
world.
Exploring nuclear motion through conical intersections in the UV photodissociation of phenols and thiophenol
Authors: Ashfold Michael N. R. , Devine Adam L. , Dixon Richard N. , King Graeme A. , Nix Michael G .D. , Oliver Thomas A. A.
Published: July 2008

High-resolution time-of-flight measurements of H atom products from photolysis of phenol, 4-methylphenol, 4-fluorophenol, and thiophenol, at many UV wavelengths (λ
phot
), have allowed systematic study of the influence of ring substituents and the heteroatom on the fragmentation dynamics. All dissociate by X

H (X = O, S) bond fission after excitation at their respective
S
1
(
1
ππ*)–
S
0
origins and at all shorter wavelengths. The achieved kinetic energy resolution reveals population of selected vibrational levels of the various phenoxyl and thiophenoxyl coproducts, providing uniquely detailed insights into the fragmentation dynamics. Dissociation in all cases is deduced to involve nuclear motion on the
1
πσ* potential energy surface (PES). The route to accessing this PES, and the subsequent dynamics, is seen to be very sensitive to λ
phot
and substitution of the heteroatom. In the case of the phenols, dissociation after excitation at long λ
phot
is rationalized in terms of radiationless transfer from
S
1
to
S
0
levels carrying sufficient O

H stretch vibrational energy to allow coupling via the conical intersection between the
S
0
and
1
πσ* PESs at longer O

H bond lengths. In contrast, H + C
6
H
5
O(X
2
B
1
) products formed after excitation at short λ
phot
exhibit anisotropic recoil-velocity distributions, consistent with prompt dissociation induced by coupling between the photoprepared
1
ππ* excited state and the
1
πσ* PES. The fragmentation dynamics of thiophenol at all λ
phot
matches the latter behavior more closely, reflecting the different relative dispositions of the
1
ππ* and
1
πσ* PESs. Additional insights are provided by the observed branching into the ground (X
2
B
1
) and first excited (
2
B
2
) states of the resulting C
6
H
5
S radicals.
Photochemistry of hydrogen-bonded aromatic pairs: Quantum dynamical calculations for the pyrrole–pyridine complex
Authors: Lan Zhenggang , Frutos Luis Manuel , Sobolewski Andrzej L. , Domcke Wolfgang
Published: July 2008

The photochemical dynamics of the pyrrole–pyridine hydrogen-bonded complex has been investigated with computational methods. In this system, a highly polar charge-transfer state of
1
ππ* character drives the proton transfer from pyrrole to pyridine, leading to a conical intersection of
S
1
and
S
0
energy surfaces. A two-sheeted potential-energy surface including 39 in-plane nuclear degrees of freedom has been constructed on the basis of
ab initio
multiconfiguration electronic-structure data. The non-Born–Oppenheimer nuclear dynamics has been treated with time-dependent quantum wave-packet methods, including the two or three most relevant nuclear degrees of freedom. The effect of the numerous weakly coupled vibrational modes has been taken into account with reduced-density-matrix methods (multilevel Redfield theory). The results provide insight into the mechanisms of excited-state deactivation of hydrogen-bonded aromatic systems via the electron-driven proton-transfer process. This process is believed to be of relevance for the ultrafast excited-state deactivation of DNA base pairs and may contribute to the photostability of the molecular encoding of the genetic information.
Indo-European and Asian origins for Chilean and Pacific chickens revealed by mtDNA
Authors: Gongora Jaime , Rawlence Nicolas J. , Mobegi Victor A. , Jianlin Han , Alcalde Jose A. , Matus Jose T. , Hanotte Olivier , Moran Chris , Austin Jeremy J. , Ulm Sean , Anderson Atholl J. , Larson Greger , Cooper Alan
Published: July 2008

European chickens were introduced into the American continents by the Spanish after their arrival in the 15th century. However, there is ongoing debate as to the presence of pre-Columbian chickens among Amerindians in South America, particularly in relation to Chilean breeds such as the Araucana and Passion Fowl. To understand the origin of these populations, we have generated partial mitochondrial DNA control region sequences from 41 native Chilean specimens and compared them with a previously generated database of ≈1,000 domestic chicken sequences from across the world as well as published Chilean and Polynesian ancient DNA sequences. The modern Chilean sequences cluster closely with haplotypes predominantly distributed among European, Indian subcontinental, and Southeast Asian chickens, consistent with a European genetic origin. A published, apparently pre-Columbian, Chilean specimen and six pre-European Polynesian specimens also cluster with the same European/Indian subcontinental/Southeast Asian sequences, providing no support for a Polynesian introduction of chickens to South America. In contrast, sequences from two archaeological sites on Easter Island group with an uncommon haplogroup from Indonesia, Japan, and China and may represent a genetic signature of an early Polynesian dispersal. Modeling of the potential marine carbon contribution to the Chilean archaeological specimen casts further doubt on claims for pre-Columbian chickens, and definitive proof will require further analyses of ancient DNA sequences and radiocarbon and stable isotope data from archaeological excavations within both Chile and Polynesia.
Monitoring cellular movementin vivowith photoconvertible fluorescence protein “Kaede” transgenic mice
Authors: Tomura Michio , Yoshida Naoki , Tanaka Junko , Karasawa Satoshi , Miwa Yoshihiro , Miyawaki Atsushi , Kanagawa Osami
Published: July 2008

Kaede is a photoconvertible fluorescence protein that changes from green to red upon exposure to violet light. The photoconversion of intracellular Kaede has no effect on cellular function. Using transgenic mice expressing the Kaede protein, we demonstrated that movement of cells with the photoconverted Kaede protein could be monitored from lymphoid organs to other tissues as well as from skin to the draining lymph node. Analysis of the kinetics of cellular movement revealed that each subset of cells in the lymph node, such as CD4+T, CD8+T, B, and dendritic cells, has a distinct migration patternin vivo. Thus, the Kaede transgenic mouse system would be an ideal tool to monitor precise cellular movementin vivoat different stages of immune response to pathogens as well as in autoimmune diseases.
Silicon as a model ion trap: Time domain measurements of donor Rydberg states
Authors: Vinh N. Q. , Greenland P. T. , Litvinenko K. , Redlich B. , van der Meer A. F. G. , Lynch S. A. , Warner M. , Stoneham A. M. , Aeppli G. , Paul D. J. , Pidgeon C. R. , Murdin B. N.
Published: July 2008

One of the great successes of quantum physics is the description of the long-lived Rydberg states of atoms and ions. The Bohr model is equally applicable to donor impurity atoms in semiconductor physics, where the conduction band corresponds to the vacuum, and the loosely bound electron orbiting a singly charged core has a hydrogen-like spectrum according to the usual Bohr–Sommerfeld formula, shifted to the far-infrared because of the small effective mass and high dielectric constant. Manipulation of Rydberg states in free atoms and ions by single and multiphoton processes has been tremendously productive since the development of pulsed visible laser spectroscopy. The analogous manipulations have not been conducted for donor impurities in silicon. Here, we use the FELIX pulsed free electron laser to perform time-domain measurements of the Rydberg state dynamics in phosphorus- and arsenic-doped silicon and we have obtained lifetimes consistent with frequency domain linewidths for isotopically purified silicon. This implies that the dominant decoherence mechanism for excited Rydberg states is lifetime broadening, just as for atoms in ion traps. The experiments are important because they represent a step toward coherent control and manipulation of atomic-like quantum levels in the most common semiconductor and complement magnetic resonance experiments in the literature, which show extraordinarily long spin lattice relaxation times—key to many well known schemes for quantum computing qubits—for the same impurities. Our results, taken together with the magnetic resonance data and progress in precise placement of single impurities, suggest that doped silicon, the basis for modern microelectronics, is also a model ion trap.
Circulating microRNAs as stable blood-based markers for cancer detection
Authors: Mitchell Patrick S. , Parkin Rachael K. , Kroh Evan M. , Fritz Brian R. , Wyman Stacia K. , Pogosova-Agadjanyan Era L. , Peterson Amelia , Noteboom Jennifer , O'Briant Kathy C. , Allen April , Lin Daniel W. , Urban Nicole , Drescher Charles W. , Knudsen Beatrice S. , Stirewalt Derek L. , Gentleman Robert , Vessella Robert L. , Nelson Peter S. , Martin Daniel B. , Tewari Muneesh
Published: July 2008

Improved approaches for the detection of common epithelial malignancies are urgently needed to reduce the worldwide morbidity and mortality caused by cancer. MicroRNAs (miRNAs) are small (≈22 nt) regulatory RNAs that are frequently dysregulated in cancer and have shown promise as tissue-based markers for cancer classification and prognostication. We show here that miRNAs are present in human plasma in a remarkably stable form that is protected from endogenous RNase activity. miRNAs originating from human prostate cancer xenografts enter the circulation, are readily measured in plasma, and can robustly distinguish xenografted mice from controls. This concept extends to cancer in humans, where serum levels of
miR-141
(a miRNA expressed in prostate cancer) can distinguish patients with prostate cancer from healthy controls. Our results establish the measurement of tumor-derived miRNAs in serum or plasma as an important approach for the blood-based detection of human cancer.
A reconstruction of the Vienna skull of
Hadropithecus stenognathus
Authors: Ryan T. M. , Burney D. A. , Godfrey L. R. , Göhlich U. B. , Jungers W. L. , Vasey N. , Ramilisonina  , Walker A. , Weber G. W.
Published: July 2008

Franz Sikora found the first specimen and type of the recently extinct
Hadropithecus stenognathus
in Madagascar in 1899 and sent it to Ludwig Lorenz von Liburnau of the Austrian Imperial Academy of Sciences. Later, he sent several more specimens including a subadult skull that was described by Lorenz von Liburnau in 1902. In 2003, some of us excavated at the locality and found more specimens belonging to this species, including much of a subadult skeleton. Two frontal fragments were found, and these, together with most of the postcranial bones, belong to the skull. CT scans of the skull and other jaw fragments were made in Vienna and those of the frontal fragments at Penn State University. The two fragments have been reunited with the skull
in silico
, and broken parts from one side of the skull have been replaced virtually by mirror-imaged complete parts from the other side. The parts of the jaw of another individual of a slightly younger dental age have also been reconstructed virtually from CT scans with mirror imaging and by using the maxillary teeth and temporomandibular joints as a guide to finish the reconstruction. Apart from forming a virtual skull for biomechanical and systematic analysis, we were also able to make a virtual endocast. Missing anterior pieces were reconstructed by using part of an endocast of the related
Archaeolemur majori
. The volume is 115 ml.
Hadropithecus
and
Archaeolemur
seem to have had relatively large brains compared with the other large-bodied subfossil lemurs.
East Asian child‐rearing attitudes: An exploration of cultural, demographic and self‐disclosure factors among US immigrants
Authors: Barry Declan T. , Bernard Matthew J. , Beitel Mark
Published: July 2008

Child‐rearing attitudes among East Asian groups have been emphasized in the developmental psychology literature in the context of their association with academic achievement. Although child‐rearing attitudes play an important role in the transmission of cultural values, much of the research on East Asian child‐rearing attitudes has ignored cultural variables and has instead focused on authoritarian parenting style. The current study examined the association between three classes of variables—culture (i.e., ethnic identity, self‐construal, acculturation), demographics (sex, years in the US, English fluency), and self‐disclosure—and traditional child‐rearing attitudes (TCRA) among East Asian immigrants in the United States. It was hypothesized that higher levels of TCRA would be associated with higher levels of ethnic identity, interdependent self‐construal, separation, and guarded self‐disclosure, and fewer years spent in the United States. The participants included 170 East Asian (Chinese, Japanese, and Korean) immigrants (88 men, 82 women) who were administered a battery of psychometrically established measures. Our hypotheses were largely supported. We found that, while there was no significant sex by ethnicity effect for TCRA, men were significantly more likely than women to endorse TCRA and the Korean group had significantly higher TCRA than the Japanese group. Ethnic identity, interdependent self‐construal, separation, years in the US, and guarded self‐disclosure were significant independent predictors of TCRA. The findings suggest the need for broadening the content of assessment tools of child‐rearing attitudes and measuring associated cultural and noncultural variables among East Asian ethnic groups. Future research on child‐rearing attitudes among Asian ethnic groups may benefit from (1) measuring multiple dimensions of TCRA, (2) assessing associated cultural variables directly rather than inferring them in an ad hoc fashion based on observed ethnicity differences, (3) measurement of demography (including sex and years spent in the host country) and (4) examining the potential influence of guarded self‐disclosure.
Fathers' involvement in young children's literacy development: Implications for family literacy programmes
Authors: Morgan Anne , Nutbrown Cathy , Hannon Peter
Published: July 2008

Relatively few studies of family literacy programmes have investigated parents' experiences and whilst a number of such programmes have been specifically aimed at fathers, little is known about the involvement of fathers in programmes which target both mothers and fathers. This article reports fathers' involvement in a family literacy programme and their home literacy practices with their young children. The article provides a definition of family literacy and describes the context of the study, which was carried out in socio‐economically disadvantaged communities in a northern English city. Fathers' participation in their children's literacy was investigated through interviews at the beginning and end of the programme (n = 85) and home visit records made by teachers throughout the programme. Quantitative and qualitative analysis of these data indicate that, while fathers' participation in the family literacy programme was not easily visible, almost all fathers were involved to some extent in home literacy events with their children. During the programme, teachers shared information about literacy activities and the importance of children having opportunities to share literacy activities with their parents. Data indicate that fathers who were not mentioned by mothers as having been involved in their children's literacy were significantly more likely to be on a low income than those who were reported as being engaged with their children in home literacy activities. Fathers in the study were involved in providing literacy opportunities, showing recognition of their children's achievements, interacting with their children around literacy and being a model of a literacy user. Although involved in all four of these key roles, fathers tended to be less involved in providing literacy opportunities than mothers. While fathers and sons engaged in what might be described as traditionally ‘masculine’ literacy activities, fathers were more often reported to be involved with their children in less obviously gendered home literacy activities. The article concludes with discussion of implications for involving fathers in future family literacy programmes.
Wanting to be ‘known’: Redefining self‐awareness through an understanding of self‐narration processes in educational transitions
Authors: Warin Jo , Muldoon Janine
Published: July 2008

The aim of this article is to initiate discussion about the pursuit of self‐awareness—a concept embedded in recent policy—as an educational goal. The authors argue that complex theoretical questions need to be addressed if improvements in policy and practice relating to personal, social and emotional education are to ensue. Such questions relate to possible interpretations of ‘self‐awareness’, a term that may be linked to outdated theories, implying a ‘self’ to be discovered and the possibility that people can sustain a ‘sense of self’ across time and place. From this perspective, self‐awareness may seem overly individualistic, obscuring more pro‐social goals (e.g. empathy, compassion, citizenship). Drawing on sociological and social psychological literature, as well as data from an empirical study of identity construction, it is hoped to contribute to the provision of firm foundations for personal, social and emotional education through a stronger theoretical exposition of ‘self‐awareness’. The authors' reconceptualised version highlights the importance of an expanded and flexible story of self, which they view as an invaluable tool for learning, fostering an openness to change.
EBNA1-specific T cells from patients with multiple sclerosis cross react with myelin antigens and co-produce IFN-γ and IL-2
Authors: Lünemann Jan D. , Jelčić Ilijas , Roberts Susanne , Lutterotti Andreas , Tackenberg Björn , Martin Roland , Münz Christian
Published: July 2008

Symptomatic primary Epstein-Barr virus (EBV) infection and elevated humoral immune responses to EBV are associated with an increased risk of developing multiple sclerosis (MS). We explored mechanisms leading to this change in EBV-specific immunity in untreated patients with MS and healthy virus carriers matched for MS-associated HLA alleles. MS patients showed selective increase of T cell responses to the EBV nuclear antigen 1 (EBNA1), the most consistently recognized EBV-derived CD4+ T cell antigen in healthy virus carriers, but not to other EBV-encoded proteins. In contrast, influenza and human cytomegalovirus–specific immune control was unchanged in MS. The enhanced response to EBNA1 was mediated by an expanded reservoir of EBNA1-specific central memory CD4+ T helper 1 (Th1) precursors and Th1 (but not Th17) polarized effector memory cells. In addition, EBNA1-specific T cells recognized myelin antigens more frequently than other autoantigens that are not associated with MS. Myelin cross-reactive T cells produced IFN-γ, but differed from EBNA1-monospecific cells in their capability to produce interleukin-2, indicative of a polyfunctional phenotype as found in controlled chronic viral infections. Our data support the concept that clonally expanded EBNA1-specific CD4+ T cells potentially contribute to the development of MS by cross-recognition of myelin antigens.
Autoregulation of Th1-mediated inflammation by twist1
Authors: Niesner Uwe , Albrecht Inka , Janke Marko , Doebis Cornelia , Loddenkemper Christoph , Lexberg Maria H. , Eulenburg Katharina , Kreher Stephan , Koeck Juliana , Baumgrass Ria , Bonhagen Kerstin , Kamradt Thomas , Enghard Philipp , Humrich Jens Y. , Rutz Sascha , Schulze-Topphoff Ulf , Aktas Orhan , Bartfeld Sina , Radbruch Helena , Hegazy Ahmed N. , Löhning Max , Baumgart Daniel C. , Duchmann Rainer , Rudwaleit Martin , Häupl Thomas , Gitelman Inna , Krenn Veit , Gruen Joachim , Sieper Jochen , Zeitz Martin , Wiedenmann Bertram , Zipp Frauke , Hamann Alf , Janitz Michal , Scheffold Alexander , Burmester Gerd R. , Chang Hyun D. , Radbruch Andreas
Published: July 2008

The basic helix-loop-helix transcriptional repressor twist1, as an antagonist of nuclear factor κB (NF-κB)–dependent cytokine expression, is involved in the regulation of inflammation-induced immunopathology. We show that twist1 is expressed by activated T helper (Th) 1 effector memory (EM) cells. Induction of twist1 in Th cells depended on NF-κB, nuclear factor of activated T cells (NFAT), and interleukin (IL)-12 signaling via signal transducer and activator of transcription (STAT) 4. Expression of twist1 was transient after T cell receptor engagement, and increased upon repeated stimulation of Th1 cells. Imprinting for enhanced twist1 expression was characteristic of repeatedly restimulated EM Th cells, and thus of the pathogenic memory Th cells characteristic of chronic inflammation. Th lymphocytes from the inflamed joint or gut tissue of patients with rheumatic diseases, Crohn's disease or ulcerative colitis expressed high levels of twist1. Expression of twist1 in Th1 lymphocytes limited the expression of the cytokines interferon-γ, IL-2, and tumor necrosis factor-α, and ameliorated Th1-mediated immunopathology in delayed-type hypersensitivity and antigen-induced arthritis.
Requirements of SLP76 tyrosines in ITAM and integrin receptor signaling and in platelet function in vivo
Authors: Bezman Natalie A. , Lian Lurong , Abrams Charles S. , Brass Lawrence F. , Kahn Mark L. , Jordan Martha S. , Koretzky Gary A.
Published: July 2008

Src homology 2 domain–containing leukocyte phosphoprotein of 76 kD (SLP76), an adaptor that plays a critical role in platelet activation in vitro, contains three N-terminal tyrosine residues that are essential for its function. We demonstrate that mice containing complementary tyrosine to phenylalanine mutations in Y145 (Y145F) and Y112 and Y128 (Y112/128F) differentially regulate integrin and collagen receptor signaling. We show that mutation of Y145 leads to severe impairment of glycoprotein VI (GPVI)–mediated responses while preserving outside-in integrin signaling. Platelets from Y112/128F mice, although having mild defects in GPVI signaling, exhibit defective actin reorganization after GPVI or αIIbβ3 engagement. The in vivo consequences of these signaling defects correlate with the mild protection from thrombosis seen in Y112/128F mice and the near complete protection observed in Y145F mice. Using genetic complementation, we further demonstrate that all three phosphorylatable tyrosines are required within the same SLP76 molecule to support platelet activation by GPVI.
Human interleukin 17–producing cells originate from a CD161+CD4+ T cell precursor
Authors: Cosmi Lorenzo , De Palma Raffaele , Santarlasci Veronica , Maggi Laura , Capone Manuela , Frosali Francesca , Rodolico Gabriella , Querci Valentina , Abbate Gianfranco , Angeli Roberta , Berrino Liberato , Fambrini Massimiliano , Caproni Marzia , Tonelli Francesco , Lazzeri Elena , Parronchi Paola , Liotta Francesco , Maggi Enrico , Romagnani Sergio , Annunziato Francesco
Published: July 2008

We demonstrate that CD161 is a highly up-regulated gene in human interleukin (IL) 17 T helper cell (Th17) clones and that all IL-17–producing cells are contained in the CD161+ fraction of CD4+ T cells present in the circulation or in inflamed tissues, although they are not CD1-restricted natural killer T cells. More importantly, we show that all IL-17–producing cells originate from CD161+ naive CD4+ T cells of umbilical cord blood, as well as of the postnatal thymus, in response to the combined activity of IL-1β and IL-23. These findings implicate CD161 as a novel surface marker for human Th17 cells and demonstrate the exclusive origin of these cells from a CD161+CD4+ T cell progenitor.
IL-17 produced by Paneth cells drives TNF-induced shock
Authors: Takahashi Nozomi , Vanlaere Ineke , de Rycke Riet , Cauwels Anje , Joosten Leo A.B , Lubberts Erik , van den Berg Wim B. , Libert Claude
Published: July 2008

Tumor necrosis factor (TNF) has very potent antitumor activity, but it also provokes a systemic inflammatory response syndrome that leads to shock, organ failure, and death. Here, we demonstrate that interleukin (IL)-17, a proinflammatory cytokine known to be produced mainly by activated T cells, has a critical role in this process. Antiserum against IL-17 or deletion of Il17r protected mice against a lethal TNF challenge. Serum levels of TNF-induced IL-6 and nitric oxide metabolites were significantly reduced in mice deficient in the IL-17R. TNF-induced leukocyte influx in the small intestine was reduced, and there was no injury to the small intestine. Surprisingly, electron microscopy showed that IL-17 was constitutively present in Paneth cells of the crypts. Upon TNF challenge, the intracellular pool of IL-17 in these cells was drastically reduced, suggesting rapid release of IL-17 from the granules of Paneth cells. Our findings assign a novel role for IL-17 in an acute inflammation and identify Paneth cells as a source of the IL-17 that plays a role in this process. These data indicate that innate immune cytokine responses in the local mucosa may participate in rapidly amplifying responses to systemic inflammatory challenges.
Poor Functional Status as a Risk Factor for Surgical Site Infection Due to Methicillin-ResistantStaphylococcus aureus
Authors: Anderson Deverick J. , Chen Luke F. , Schmader Kenneth E. , Sexton Daniel J. , Choi Yong , Link Katherine , Sloane Rick , Kaye Keith S.
Published: July 2008

Objective.

To identify risk factors for surgical site infection (SSI) due to methicillin-resistantStaphylococcus aureus(MRSA).

Design.

Prospective case-control study.

Setting.

One tertiary and 6 community-based institutions in the southeastern United States.

Methods.

We compared patients with SSI due to MRSA with 2 control groups: matched uninfected surgical patients and patients with SSI due to methicillin-susceptibleS. aureus(MSSA). Multivariable logistic regression was used to determine variables independently associated with SSI due to MRSA, compared with each control group.

Results.

During the 5-year study period, 150 case patients with SSI due to MRSA were identified and compared with 231 matched uninfected control patients and 128 control patients with SSI due to MSSA. Two variables were independendy associated with SSI due to MRSA in both multivariable regression models: need for assistance with 3 or more activities of daily living (odds ratio [OR] compared with uninfected patients, 3.97 [95% confidence interval {CI}, 2.18-7.25]; OR compared with patients with SSI due to MSSA, 3.88 [95% CI, 1.91-7.87]) and prolonged duration of surgery (OR compared with uninfected patients, 1.98 [95% CI, 1.11-3.55]; OR compared with patients with SSI due to MSSA, 2.33 [95% CI, 1.17-4.62]). Lack of independence (ie, poor functional status) remained associated with an increased risk of SSI due to MRSA after stratifying by age.

Conclusions.

Poor functional status was highly associated with SSI due to MRSA in adult surgical patients, regardless of age. A patient's level of independence can be easily determined, and this information can be used preoperatively to target preventive interventions.