bluuebunny/crossref_metadata_2025 huggingface dataset:
The progression of moxibustion therapy in Tang and Song Dynasty folk medicine: An analysis on the background of technology choice
Authors: Gengzhe YU
Published: July 2007

The changing status of moxibustion therapy in folk medicine from the Tang Dynasty to the Song Dynasty is a reflection of the distribution situation of popular medical resources during these periods. As a feasible therapy with a large popularity, moxibustion played a crucial role in the Tang Dynasty. The Song Dynasty saw some social development as well, because it was an active state power and social force in medical activities. Therefore, people at the lower class gradually benefited from decoction and acupuncture treatments, and the status of the moxibustion therapy began to decline. The changing status of moxibustion therapy in different dynasties embodies the changes in technology and the quality of life.
The social background of the emergence of regional merchant groups in the Ming Dynasty
Authors: Jinmin FAN
Published: July 2007

In the mid-Ming Dynasty, the means of transportation were greatly improved; commodity production became more developed; silver was gradually monetized; commercial taxes became lighter; and social attitudes towards merchants changed. All these developments created a favorable environment for the formation of regional merchant groups. Meanwhile, social factors at the regional level—characteristics of local commodity production, favorable natural environment and production structures, as well as Ming government’s practice of border defense, border trade, foreign policy, local customs, and the interpretation of commercial activities of local people—all contributed to the emergence of merchant groups.
ZnO Nanorods via Spray Deposition of Solutions Containing Zinc Chloride and Thiocarbamide
Authors: Dedova Tatjana , Volobujeva Olga , Klauson Jelena , Mere Arvo , Krunks Malle
Published: July 2007

In this work we present the results on formation of ZnO nanorods prepared by spray of aqueous solutions containing ZnCl2and thiocarbamide (tu) at different molar ratios. It has been observed that addition of thiocarbamide into the spray solution has great impact on the size, shape and phase composition of the ZnO crystals. Obtained layers were characterized by scanning electron microscopy (SEM) equipped with energy selected backscattered electron detection system (ESB), X-ray diffraction (XRD) and photoluminescence spectroscopy (PL). Small addition of thiocarbamide into ZnCl2solution (ZnCl2:tu = 1:0.25) supports development of significantly thinner ZnO nanorods with higher aspect ratio compared to those obtained from ZnCl2solution. Diameter of ZnO rods decreases from 270 to 100 nm and aspect ratio increases from ∼2.5 to 12 spraying ZnCl2and ZnCl2:tu solutions, respectively. According to XRD, well crystallized (002) orientated pure wurtzite ZnO crystals have been formed. However, tiny ‘spot’—like formations of ZnS were detected on the side planes of hexagonal rods prepared from the thiocarbamide containing solutions. Being adsorbed on the side facets of the crystals ZnS inhibits width growth and promotes longitudinalc-axis growth.
The anteromedial approach to the psoas tendon in patients with cerebral palsy
Authors: Poonnoose Pradeep M. , Madhuri Vrisha , Palocaren Thomas
Published: July 2007

Purpose

Release of the psoas tendon for flexion deformity of the hip in children with cerebral palsy has traditionally been performed at the pelvic brim, lateral to the neurovascular bundle, or at its insertion into the lesser trochanter. As the psoas tendon is lateral to the pectineus, the traditional exposure of the tendon through an approach medial to the pectineus is limited by the extent to which the pectineus can be retracted proximally.

Technical note

We describe the use of the anteromedial approach used for the developmentally dislocated hip to expose the psoas tendon between the pectineus and the neurovascular bundle. This provides a much better visualisation of the tendon as it crosses the superior pubic ramus to its insertion. The use of this approach has not been described in cerebral palsy.
Existence, non-existence and regularity of radial ground states for p-Laplacian equations with singular weights
Authors: Pucci Patrizia , Servadei Raffaella
Published: July 2007

By the Mountain Pass Theorem and the constrained minimization method existence of positive or compactly supported radial ground states for quasilinear singular elliptic equations with weights are established. The paper also includes the discussion of regularity and the validity of useful qualitative properties of the solutions, which seems of independent interest. Finally, a Pohozaev type identity is produced to deduce some non-existence results.
Who Would Marry a Strong Woman? A Short Story by Bhagvaticharan Varma
Authors: DAMSTEEGT THEO
Published: July 2007

In Varma's story ‘Pata-banethi’, a robust young man refuses to marry a female student when he finds out that she is trained in defensive violence, as a virangana. At first sight, the story appears to draw attention to the difficulties women trained like men in fighting will have in getting married and finding a place in society. An analysis of characterisation, however, suggests that Varma's story goes against such a stereotypic male evaluation of strong women, and actually underlines the social and political value of violence controlled by mental strength, a value that can be recognised by both men and women.
Resource depletion inAedes aegyptimosquitoes infected by the microsporidiaVavraia culicis
Authors: RIVERO A. , AGNEW P. , BEDHOMME S. , SIDOBRE C. , MICHALAKIS Y.
Published: July 2007

Parasitic infection is often associated with changes in host life-history traits, such as host development. Many of these life-history changes are ultimately thought to be the result of a depletion or reallocation of the host's resources driven either by the host (to minimize the effects of infection) or by the parasite (to maximize its growth rate). In this paper we investigate the energetic budget ofAedes aegyptimosquito larvae infected byVavraia culicis, a microsporidian parasite that transmits horizontally between larvae, and which has been previously shown to reduce the probability of pupation of its host. Our results show that infected larvae have significantly less lipids, sugars and glycogen than uninfected larvae. These differences in resources were not due to differences in larval energy intake (feeding rate) or expenditure (metabolic rate). We conclude that the lower energetic resources of infected mosquitoes are the result of the high metabolic demands that microsporidian parasites impose on their hosts. Given the fitness advantages for the parasite of maintaining the host in a larval stage, we discuss whether resource depletion may also be a parasite mechanism to prevent the pupation of the larvae and thus maximize its own transmission.
Heading for Retirement? National Insurance, State Pensions, and the Future of the Contributory Principle in the UK
Authors: HILLS JOHN
Published: July 2007

This article discusses the implications of the decline of National Insurance in Britain, witnessed by its declining share of social security spending and steady dilution of the ‘contributory principle’ on which it was originally based. This decline is not accidental: under governments of the Left, arguments for inclusion have predominated, non-contributory benefits expanded and contribution conditions softened; under those of the Right, limited resources have been focused on the poorest through means-testing. From this starting point, the strong arguments in principle for social insurance look much weaker. However, there are also reasons why the system has not been swept away, notably the way in which most of it concerns already accrued state pension rights.

The effect of current plans for state pensions is to restore something closer to a flat rate state pension, but with significant complexity. The article suggests a way in which a more transparent system could guarantee a total state pension at a fixed percentage of average earnings. Other National Insurance benefits could either be separated from pensions and absorbed within other working age social security, or the scope of National Insurance could be maintained, but based on a test of participation, not past contributions.
Housing Expenditures and Income Poverty in EU Countries
Authors: FAHEY TONY , NOLAN BRIAN , MÂITRE BERTRAND
Published: July 2007

Previous research has suggested that hidden income arising from home ownership has important consequences for poverty measurement as it tends to favour certain low income groups, especially the elderly, and to have a moderating effect on poverty rates in countries with high levels of home ownership. This article explores both methodological and substantive aspects of this issue using data for 14 EU countries drawn from the European Community Household Panel Survey 1996. Methodologically, in the absence of data needed to estimate hidden income from housing directly, it explores the validity of using a housing expenditures approach to take account of the income effects of housing in a poverty measurement context. Substantively, it examines whether poverty measured in this way in the 14 countries in the data set differs in expected directions from poverty as conventionally measured. The substantive effects are found to be modest overall and to conform only partially to expectations. Certain methodological problems raise a question mark over these findings, such as variation across countries in the degree to which mortgage payments capture the cost of house purchase for home owners. The article concludes that the distributive effects of housing are important for poverty measurement but need to be better understood within each country before attempting cross-country analysis.
Two-year-olds use primary sentence accent to learn new words
Authors: GRASSMANN SUSANNE , TOMASELLO MICHAEL
Published: July 2007

German children aged 2 ; 1 heard a sentence containing a nonce noun and a nonce verb (Der Feks miekt). Either the noun or the verb was prosodically highlighted by increased pitch, duration and loudness. Independently, either the object or the action in the ongoing referential scene was the new element in the situation. Children learned the nonce noun only when it was both highlighted prosodically and the object in the scene was referentially new. They did not learn the nonce verb in any condition. These results suggest that from early in linguistic development, young children understand that prosodic salience in a sentence indicates referential newness.
How children process over-regularizations: Evidence from event-related brain potentials
Authors: CLAHSEN HARALD , LÜCK MONIKA , HAHNE ANJA
Published: July 2007

This study examines the mental processes involved in children's on-line recognition of inflected word forms using event-related potentials (ERPs). Sixty children in three age groups (20 six- to seven-year-olds, 20 eight- to nine-year-olds, 20 eleven- to twelve-year-olds) and 23 adults (tested in a previous study) listened to sentences containing correct or incorrect German noun plural forms. In the two older child groups, as well as in the adult group, over-regularized plural forms elicited brain responses that are characteristic of combinatorial (grammatical) violations. We also found that ERP components associated with language processing change from child to adult with respect to their onsets and their topography. The ERP violation effects obtained for over-regularizations suggest that children (aged eight years and above) and adults employ morphological computation for processing purposes, consistent with dual-mechanism models of inflection. The observed differences between children's and adults' ERP responses are argued to result from children's smaller lexicons and from slower and less efficient processing.
Characterizing communicative development in children referred for Autism Spectrum Disorders using the MacArthur-Bates Communicative Development Inventory (CDI)
Authors: LUYSTER RHIANNON , LOPEZ KRISTINA , LORD CATHERINE
Published: July 2007

Characterizing early communicative development in children with Autism Spectrum Disorders (ASD) is valuable for understanding profiles of ability in this population. The current investigation was modeled on Charman, Drew, Baird & Baird (2003b). Analyses explored parent report of early vocabulary, non-verbal communication, functional object use and play skills on the MacArthur-Bates Communicative Development Inventory (CDI) in 93 children with ASD, 31 children with developmental delay (DD) and 29 typically developing children. Results were generally consistent with those of Charman and colleagues (2003b), suggesting that skills improve with increasing non-verbal mental age and chronological age but that most children with ASD are delayed in receptive and expressive vocabulary and non-verbal communication, functional object use and play skills. Vocabulary profiles in the ASD sample were similar to those in the comparison samples, as was the developmental pattern of gesture and vocabulary mastery. However, when compared to published norms, children with ASD may show less of a discrepancy between their receptive and expressive vocabulary.
Social contacts of school children and the transmission of respiratory-spread pathogens
Authors: MIKOLAJCZYK R. T. , AKMATOV M. K. , RASTIN S. , KRETZSCHMAR M.
Published: July 2007

Empirical data about contact frequencies of children is needed for estimating parameters in mathematical modelling studies that investigate the effect of targeting influenza intervention to children. A survey about the social contacts of school children was conducted in a primary school in Germany. The distribution of the daily numbers of contacts was stratified by age of the contacted person and by weekday. A negative binomial regression analysis was performed to investigate factors that influence contact behaviour. Using logistic regression analysis we examined the relationship between the numbers of private contacts and having been ill in the last 6 months. We computed effective contact numbers to take the heterogeneity in contact behaviour into account in assessing the contribution of children's contacts to the overall transmission of an infection. The possible effects of intervention measures such as school closure and vaccination on the transmission of respiratory-spread agents to other age groups are discussed.
Teasing Apart Two Trees
Authors: STEEL M. A. , SZÉKELY L. A.
Published: July 2007

A widely studied model for generating binary sequences is to ‘evolve’ them on a tree according to a symmetric Markov process. We show that under this model distinguishing the true (model) tree from a false one is substantially ‘easier’ (in terms of the sequence length needed) than determining the true tree. The key tool is a new and near-tight Ramsey-type result for binary trees.
Familial muscular ventricular septal defects and aneurysms of the muscular interventricular septum
Authors: Nicolae Mugur I. , Summers Kim M. , Radford Dorothy J.
Published: July 2007

We describe 3 siblings with muscular ventricular septal defects, two requiring surgical closure. One of their offspring had a rare congenital aneurysm of the muscular ventricular septum, also requiring surgery. Another had a small muscular ventricular septal defect which closed spontaneously. Their father had echocardiographic evidence suggestive of a closed muscular defect. Paternal cousins have had ventricular septal defect, hypertrophic cardiomyopathy, and tetralogy of Fallot. There was no evidence of 22q11 deletion.

Although ventricular septal defects are the most common congenital heart defect, such familial clustering is uncommon. The distribution of cases in this family suggests autosomal dominant inheritance. With echocardiography, and more precise diagnosis of defects which close, a larger genetic component may be revealed in other families.
Impact of placing a conduit from the right ventricle to the pulmonary arteries as the first stage of further palliation in the Norwood sequence for hypoplasia of the left heart
Authors: Kostolny Martin , Hoerer Juergen , Eicken Andreas , Dietrich Claudia , Schreiber Christian F. , Lange Ruediger
Published: July 2007

Objective

We describe the experience from a single institution with the Norwood sequence of palliation for hypoplasia of the left heart, emphasizing complications related to placement of a conduit from the right ventricle to the pulmonary arteries and their management.

Methods

Between November, 2002 and January, 2006, we palliated 32 patients with hypoplastic left heart syndrome or its variants by placing a conduit from the right ventricle to the pulmonary arteries. We reviewed retrospectively the charts and angiograms from these patients.

Results

Hospital survival after construction of the conduit was 90.6%. There were 3 interstage deaths, of which 2 were likely due severe obstruction of the conduit. Stents were implanted into the proximal or medial portions of the conduits of 3 patients. Early revision of the distal anastomosis, and shortening the conduit, was performed early postoperatively in 2 patients. So far, 24 out 26 survivors of the first stage underwent a bi-directional cavopulmonary anastomosis after a mean interval of 4.3 plus or minus 1.4 months. Of these, 3 required a semi-urgent second stage of palliation because of worsening cyanosis, with one patient dying after the second stage. Completion of the Fontan circulation by insertion of an extracardiac conduit was performed in 8 patients at the mean age of 19.8 plus or minus 2.2 months. We were able to achieve biventricular repair in 1 patient, with aortic atresia, hypoplastic arch and ventricular septal defect, 4.3 months after the initial palliative procedure. Overall survival of the whole cohort of 32 patients was 78.9%, plus or minus 7.8%, at 5 months, and 74.3%, plus or minus 8.6%, up to 25 months.

Conclusions

The introduction of the conduit placed from the right ventricle to the pulmonary arteries has led to an improved outcome in the complex entity of hypoplastic left heart syndrome and its variants. Stenosis of the conduit, nonetheless, may account for significant interstage morbidity, and often requires intervention or early installation of the second stage of palliation.
“Sobre las olas”: Cultural Synecdoche of the Past
Authors: MAGDANZ TERESA
Published: July 2007

Composed in 1888 by Juventino Rosas, the waltz “Sobre las olas” (“Over the Waves”) soon made its way to North America and beyond, reverberating in the great spaces of the circus, fairground, skating rink, dance hall, and park. Recycled in cartoons and films, in television, and in various cover versions, Rosas's waltz has become a kind of popular liminal music. The complex, circuitous routes it has traveled have led to a present-day musical convention. This essay attempts to lay bare the mechanisms at work in the dissemination of such a widely known piece of music in three ways: 1) by accounting for the multiple themes related to “Sobre las olas”; 2) by considering the range of technologies through which Rosas's waltz has been disseminated; and 3) by theorizing public knowledge of the waltz as a musical “quote,” a snippet recognizable after a few notes.
The Multiple Voices of American Klezmer
Authors: WOOD ABIGAIL
Published: July 2007

Since the 1970s, klezmer has undergone a revival and radical transformation. Originally a European Jewish music, klezmer is now a staple of the world music scene. Although the fusion of instrumental and vocal genres under a single musical umbrella is a significant marker of change between the Old World and revived klezmer repertories, the extension of the boundaries of the klezmer repertory to encompass vocal material has largely been overlooked by practitioners and scholars. This article reinstates song in the narrative of the klezmer revival, exploring how and why it has assumed its prominent position. In case studies of three ensembles, song gives insight into the sensibilities of individual musicians and offers a prism through which to consider contemporary klezmer as both an American Jewish heritage music and a world music genre.
Therapeutic Benefits by Human Mesenchymal Stem Cells (hMSCs) and Ang-1 Gene-Modified hMSCs after Cerebral Ischemia
Authors: Onda Toshiyuki , Honmou Osamu , Harada Kuniaki , Houkin Kiyohiro , Hamada Hirofumi , Kocsis Jeffery D
Published: July 2007

Transplantation of human mesenchymal stem cells (hMSCs) prepared from adult bone marrow has been reported to ameliorate functional deficits after cerebral artery occlusion in rats. Although several hypotheses to account for these therapeutic effects have been suggested, current thinking is that both neuroprotection and angiogenesis are primarily responsible. In this study, we compared the effects of hMSCs and angiopoietin-1 gene-modified hMSCs (Ang-hMSCs) intravenously infused into rats 6 h after permanent middle cerebral artery occlusion. Magnetic resonance imaging and histologic analyses revealed that rats receiving hMSCs or Ang-hMSCs exhibited comparable reduction in gross lesion volume as compared with the control group. Although both cell types indeed improved angiogenesis near the border of the ischemic lesions, neovascularization and regional cerebral blood flow were greater in some border areas in Ang-hMSC group. Both hMSC- and Ang-hMSC-treated rats showed greater improved functional recovery in the treadmill stress test than did control rats, but the Ang-hMSC group was greater. These results indicate the intravenous administration of genetically modified hMSCs to express angiopoietin has a similar effect on reducing lesion volume as hMSCs, but the Ang-hMSC group showed enhanced regions of increased angiogenesis at the lesion border, and modest additional improvement in functional outcome.
Ion and electron local transport inside single helicity islands in the reversed field pinch
Authors: Gobbin M. , Marrelli L. , Martin P. , White R. B.
Published: July 2007

The ion and electron diffusion coefficients inside the helical magnetic core in a single helicity reversed field pinch (RFP) toroidal plasma have been numerical determined by a Monte Carlo test particle approach. A new algorithm aimed at approximating with polyhedra the magnetic surfaces obtained with Poincaré cross sections has been developed. Stationary simulations of test ion and electron transport have been performed: they allow the determination of the average diffusion coefficients inside the helical core both for ions and electrons, which are much lower than those found in standard multiple helicity plasmas. Results are discussed and compared with those found in previous RFP simulations. The technique may be relevant also for stellarator and tokamak studies.
Direct x-ray detection with conjugated polymer devices
Authors: Boroumand F. A. , Zhu M. , Dalton A. B. , Keddie J. L. , Sellin P. J. , Gutierrez J. J.
Published: July 2007

The authors report the first direct detection of x-ray induced photocurrents in thick films (up to 20μm) of conjugated polymers. Schottky-based “sandwich” structures were fabricated from layers of either poly[1-methoxy-4-(2-ethylhexyloxy)-phenylenevinylene] (MEH-PPV) or poly(9,9-dioctylfluorene) (PFO) on indium tin oxide substrates using a top contact of aluminum. Good rectification was achieved from the Al-polymer contact, with a reverse bias leakage current density as low as 4nA∕cm2 at an electric field strength of 25kV∕cm. Irradiation with x-rays from a 50kV x-ray tube produced a linear increase in photocurrent over a dose rate range from 4to18mGy∕s. The observed x-ray sensitivities of 240nC∕mGy∕cm3 for MEH-PPV and 480nC∕mGy∕cm3 for PFO structures are comparable to that reported for Si devices. A response time of <150ms to pulsed x-ray irradiation was measured with no evidence of long-lived current transients. Conjugated polymers offer the advantage of easy coatability over large areas and on curved surfaces. Their low average atomic number provides tissue-equivalent dosimetric response, with many potential applications including medical x-ray and synchrotron photon detection.
Molecular Zeeman spectroscopy for H2 Fulcher-α band spectra as a local measurement of rovibrational structures
Authors: Shikama T. , Kado S. , Zushi H. , Tanaka S.
Published: July 2007

A diagnostic technique for the local measurement of emissions from the molecular hydrogen has been developed. In the presence of an external magnetic field, the emission position can be deduced from the Zeeman patterns in the spectral line shape, and with the aid of the coronal model the rovibronic emission intensity provides the local rovibrational temperatures. In order to evaluate the Zeeman effect on the hydrogen molecule, a quantum-mechanical calculation is performed. The experimentally observed Fulcher-α rovibronic band spectra under a magnetic field strength of about 7T are well represented by the calculation. The temporal evolution of the emission position as well as the rovibrational temperatures are measured in the 8.2GHz lower hybrid current drive discharges of the TRIAM-1M tokamak [H. Zushi et al., Nucl. Fusion 45, S142 (2005)]. The measured emission is found to originate from the region where the plasma comes in contact with the limiter, and the observed increase in the rotational temperature suggests a rise in the limiter surface temperature.
Theory of cosmological seed magnetic fields
Authors: Saleem H.
Published: July 2007

A theory for the generation of seed magnetic field and plasma flow on cosmological scales driven by externally given baroclinic vectors is presented. The Beltrami-like plasma fields can grow from zero values at initial time t=0 from a nonequilibrium state. Exact analytical solutions of the set of two-fluid equations are obtained that are valid for large plasma β-values as well. Weaknesses of previous models for seed magnetic field generation are also pointed out. The analytical calculations predict the galactic seed magnetic field generated by this mechanism to be of the order of 10−14G, which may be amplified later by the αω dynamo (or by some other mechanism) to the present observed values of the order of ∼(2–10)μG. The theory has been applied to laser-induced plasmas as well and the estimate of the magnetic field’s magnitude is in agreement with the experimentally observed values.
Zonal flows in toroidal systems
Authors: Mynick H. E. , Boozer A. H.
Published: July 2007

An analytic study of the shielding and time evolution of zonal flows in tokamaks and stellarators is presented, using the action-angle formalism. This framework permits one to solve the kinetic equation without expansion of that equation in small parameters of radial excursions and time scales, resulting in more general expressions for the dielectric shielding, and with a scaling extended from that in earlier work. From these expressions, it is found that for each mechanism of collisional transport, there is a corresponding shielding mechanism, of closely related form and scaling. The effect of these generalized expressions on the evolution and size of zonal flows, and their implications for stellarator design are considered.
Low frequency noise in highly sensitive magnetic tunnel junctions with (001) MgO tunnel barrier
Authors: Mazumdar Dipanjan , Liu Xiaoyong , Schrag B. D. , Carter Matthew , Shen Weifeng , Xiao Gang
Published: July 2007

Low frequency voltage noise was measured in highly sensitive magnetic tunnel junctions with MgO tunnel barrier. The voltage noise is observed to scale linearly with the magnetic field sensitivity. Fluctuations in noise, possibly due to local domain nucleation or annihilation inside the free layer, are also observed. Results indicate that an external hard-axis bias field can significantly suppress the magnetization fluctuations of the free layer and lower the magnetic field noise.
Small-angle x-ray scattering measurement of a mist of ethanol nanodroplets: An approach to understanding ultrasonic separation of ethanol-water mixtures
Authors: Yano Yohko F. , Matsuura Kazuo , Fukazu Tetsuo , Abe Fusatsugu , Wakisaka Akihiro , Kobara Hitomi , Kaneko Kazuyuki , Kumagai Atsushi , Katsuya Yoshio , Tanaka Masahiko
Published: July 2007

Small-angle x-ray scattering measurements using a brilliant x-ray source revealed nanometer sized liquid droplets in a mist formed by ultrasonic atomization. Ultrasonic atomization of ethanol-water mixtures produced a combination of water-rich droplets of micrometer order and ethanol-rich droplets as small as 1nm, which is 10−3 times smaller than the predicted size. These sizes were also obtained for mists generated from the pure liquids. These results will help to clarify the mechanism of “ultrasonic ethanol separation,” which has the potential to become an alternative to distillation.
Amorphous Mg-based metal foams with ductile hollow spheres
Authors: Brothers A. H. , Dunand D. C. , Zheng Q. , Xu J.
Published: July 2007

To date, high compressive ductility and energy absorption have been achieved in amorphous metal foams based on high-toughness Pd- and Zr-based metallic glasses and are known to result from two extrinsic toughening mechanisms: bending of struts and shear band arrest by pores. We study here a syntactic amorphous metallic foam produced by infiltration of a bed of hollow crystalline iron spheres with a low-toughness Mg-based metallic glass (Mg60Cu21Ag7Gd12). After quenching to vitrify the matrix, this foam exhibits much higher compressive failure strain and energy absorption than the monolithic metallic glass, an improvement which is assigned to an intrinsic mechanism, i.e., composite toughening by the network of hollow ductile iron spheres.
A molecular dynamics study of nanoindentation of amorphous silicon carbide
Authors: Szlufarska Izabela , Kalia Rajiv K. , Nakano Aiichiro , Vashishta Priya
Published: July 2007

Through molecular dynamics simulation of nanoindentation of amorphous a-SiC, we have found a correlation between its atomic structure and the load-displacement (P-h) curve. We show that a density profile of a-SiC exhibits oscillations normal to the surface, analogous to liquid metal surfaces. Short-range P-h response of a-SiC is similar to that of crystalline 3C-SiC, e.g., it shows a series of load drops associated with local rearrangements of atoms. However, the load drops are less pronounced than in 3C-SiC due to lower critical stress required for rearrangement of local clusters of atoms. The nanoindentation damage is less localized than in 3C-SiC. The maximum pressure under the indenter is 60% lower than in 3C-SiC with the same system geometry. The onset of plastic deformation occurs at the depth of 0.5Å, which is ∼25% of the corresponding value in 3C-SiC. a-SiC exhibits lower damping as compared to 3C-SiC, which is reflected in the longer relaxation time of transient forces after each discrete indentation step.
Bistable electrical switching and write-once read-many-times memory effect in a donor-acceptor containing polyfluorene derivative and its carbon nanotube composites
Authors: Liu Gang , Ling Qi-Dan , Kang En-Tang , Neoh Koon-Gee , Liaw Der-Jang , Chang Feng-Chyuan , Zhu Chun-Xiang , Chan D. Siu-Hung
Published: July 2007

A conjugated copolymer of 9,9-didodecylfluorene and 4-triphenylamino-2,6-bis(phenyl)pyridine (F12TPN), containing both electron donor and acceptor moieties, was synthesized via Suzuki coupling polymerization. Polymer memory devices, based on thin films of F12TPN and its carbon nanotube composites, were fabricated. The current density-voltage characteristics of the indium tin oxide (ITO)/F12TPN/Al sandwich structure could be switched from a low conductivity (off) state to a high conductivity (on) state, when operated under negative bias with ITO as the anode. The switch-on voltage of the as-fabricated device was around −2.3V. The on/off state current ratio was about 10. The on/off state current ratio could be enhanced to 105 and the switch-on voltage reduced to about −1.7V by doping the F12TPN layer with about 1wt% of carbon nanotubes. Once the memory devices had been switched on, they could not be erased (switched off) with a reverse bias (positive bias). Thus the memory effect was characteristics of that of a write-once read-many-times memory. The memory mechanism was deduced from molecular simulation and modeling of the nature of currents in both states.
Effects of interface engineering for HfO2 gate dielectric stack on 4H-SiC
Authors: Mahapatra R. , Chakraborty Amit K. , Horsfall A. B. , Chattopadhyay S. , Wright N. G. , Coleman Karl S.
Published: July 2007

Hf O 2 films were grown on SiO2∕4H-SiC and SiON∕4H-SiC layers by deposition of metallic Hf in an electron beam evaporation system followed by thermal oxidation. X-ray photoelectron spectroscopy confirmed the formation of stoichiometric HfO2 films. There is no evidence of formation of hafnium silicide or carbon pileup at the surface as well as at the interfacial layer. Electrical measurements show the presence of fewer trapped charges in the HfO2∕SiON gate dielectric stack compared to HfO2∕SiO2 stack with a comparable interface state density. The HfO2∕SiON stack layer improves leakage current characteristics with a higher breakdown field and has smaller flatband voltage shift under electrical stress, indicating improved reliability.
Development of compact high precision linear piezoelectric stepping positioner with nanometer accuracy and large travel range
Authors: Kang Dongwoo , Lee Moon G. , Gweon Daegab
Published: July 2007

Many application areas such as semiconductor manufacture, precision optics alignment, and microbiological cell manipulation require ultraprecision positioning systems with a high positioning resolution and large motion range. This article describes the development of a compact high precision linear piezoelectric stepping positioner for precision alignment of optical elements. The positioner is designed to have a compact and symmetric structure, high positioning resolution, large motion range, high force density, adequate dynamic range, and power-off hold. The positioner is fabricated according to these specifications and performance evaluation tests are carried out. A resolution of 10nm, speed of 1mm∕s, push force of 25N, and stiffness of 10.4N∕μm are attained while maintaining a compact size of 32×42×60mm3. The required power consumption is 52.33W. The test results confirm that the developed positioner could be successfully applied to the precision alignment of optical elements.
Size-dependent DNA mobility in nanochannels
Authors: Cross Joshua David , Strychalski Elizabeth A. , Craighead H. G.
Published: July 2007

Nanofluidic slits are used to investigate surface interactions during electrophoresis between DNA molecules and channel walls. The channels have vertical dimensions of 19 and 70nm and contain no sieving matrix. Size-dependent mobility is observed for DNA in the 19nm channels. We present a model for double stranded DNA mobility in the nanochannels that accurately predicts the size dependence of the DNA mobility in the range of 2000–10000bp. Due to surface interactions, the DNA mobility in the nanochannels scales as N−1∕2. These results suggest that the notion of free solution DNA electrophoresis breaks down due to surface interactions in nanoscale environments.
Low-frequency charge noise in suspended aluminum single-electron transistors
Authors: Li T. F. , Pashkin Yu. A. , Astafiev O. , Nakamura Y. , Tsai J. S. , Im H.
Published: July 2007

The authors have developed a fabrication method for suspended metallic single-electron transistors (SETs) utilizing a combination of conventional angle evaporation technique and ashing of the underlying organic polymer. The authors’ Al-based suspended devices exhibit clear Coulomb blockade effects typical for conventional SETs. The measured low-frequency charge noise is rather low but still within the range reported for conventional Al devices. We suggest that the noise level can be further reduced by decreasing the effective SET temperature.
Electrochromic properties of intercrossing nickel oxide nanoflakes synthesized by electrochemically anodic deposition
Authors: Wu Mao-Sung , Yang Chung-Hsien
Published: July 2007

Nanostructured nickel oxide film is synthesized directly onto a transparent and conducting indium tin oxide coated glass substrate by electrochemically anodic deposition from an aqueous solution. The deposited nickel oxide film has an intercrossing nanoflake and highly porous morphology. X-ray diffraction peaks of the film resemble closely to the cubic NiO structure. The deposited film oxidized/reduced electrochemically at 0.36 and 0.25V versus a saturated Ag∕AgCl electrode, respectively, which corresponds to the reversible changes in coloration and bleaching. The difference in optical response (transmittance) ΔT at wavelength of 550nm between the colored state and bleached state can reach as high as 80%.
Population inversion by resonant tunneling in quantum wells
Authors: Scalari Giacomo , Terazzi Romain , Giovannini Marcella , Hoyler Nicolas , Faist Jérôme
Published: July 2007

A terahertz quantum cascade laser based on a single quantum well active region is reported. It displays laser action at 3.74THz with low threshold current densities around 30A∕cm2. Analysis of the optical and electrical characteristics and their comparison with a transport model based on a density matrix approach clearly demonstrate the role of resonant tunneling for both injection and extraction of the electrons from the upper and lower states of the laser transition.
Promoter-associated RNA is required for RNA-directed transcriptional gene silencing in human cells
Authors: Han Jiang , Kim Daniel , Morris Kevin V.
Published: July 2007

siRNAs targeted to gene promoters can direct epigenetic modifications that result in transcriptional gene silencing in human cells. It is not clear whether the antisense strand of the siRNAs bind directly to DNA or to a sense-stranded RNA transcript corresponding to the known promoter region. We present evidence that an RNA polymerase II expressed mRNA containing an extended 5′ untranslated region that overlaps the gene promoter is required for RNA-directed epigenetic modifications and transcriptional silencing of the RNA-targeted promoter. These promoter-associated RNAs were detected by their hybridization to the antisense strand of the complementary promoter-directed siRNA. Antisense phosphorothioate oligodeoxynucleotides were used to degrade the promoter-associated RNA transcripts, the loss of which abrogated the effect of siRNA-mediated transcriptional gene silencing, as well as the complexing of the siRNA with the silent state histone methyl mark and the promoter-associated RNA. These data demonstrate that low-copy promoter-associated RNAs transcribed through RNAPII promoters are recognized by the antisense strand of the siRNA and function as a recognition motif to direct epigenetic silencing complexes to the corresponding targeted promoters to mediate transcriptional silencing in human cells.
Crystal structure of the chromophore binding domain of an unusual bacteriophytochrome, RpBphP3, reveals residues that modulate photoconversion
Authors: Yang Xiaojing , Stojković Emina A. , Kuk Jane , Moffat Keith
Published: July 2007

Bacteriophytochromes RpBphP2 and RpBphP3 from the photosynthetic bacterium
Rhodopseudomonas palustris
work in tandem to modulate synthesis of the light-harvesting complex LH4 in response to light. Although RpBphP2 and RpBphP3 share the same domain structure with 52% sequence identity, they demonstrate distinct photoconversion behaviors. RpBphP2 exhibits the “classical” phytochrome behavior of reversible photoconversion between red (Pr) and far-red (Pfr) light-absorbing states, whereas RpBphP3 exhibits novel photoconversion between Pr and a near-red (Pnr) light-absorbing states. We have determined the crystal structure at 2.2-Å resolution of the chromophore binding domains of RpBphP3, covalently bound with chromophore biliverdin IXα. By combining structural and sequence analyses with site-directed mutagenesis, we identify key residues that directly modulate the photochemical properties of RpBphP3 and RpBphP2. Remarkably, we identify a region spanning residues 207–212 in RpBphP3, in which a single mutation, L207Y, causes this unusual bacteriophytochrome to revert to the classical phenotype that undergoes reversible photoconversion between the Pr and Pfr states. The reverse mutation, Y193L, in the corresponding region in RpBphP2 significantly diminishes the formation of the Pfr state. We propose that residues 207–212 and the spatially adjacent conserved residues, Asp-216 and Tyr-272, interact with the chromophore and form part of the interface between the chromophore binding domains and the PHY domain that modulates photoconversion.
Fiber-dependent amyloid formation as catalysis of an existing reaction pathway
Authors: Ruschak Amy M. , Miranker Andrew D.
Published: July 2007

A central component of a number of degenerative diseases is the deposition of protein as amyloid fibers. Self-assembly of amyloid occurs by a nucleation-dependent mechanism that gives rise to a characteristic sigmoidal reaction profile. The abruptness of this transition is a variable characteristic of different proteins with implications to both chemical mechanism and the aggressiveness of disease. Because nucleation is defined as the rate-limiting step, we have sought to determine the nature of this step for a model system derived from islet amyloid polypeptide. We show that nucleation occurs by two pathways: a fiber-independent (primary) pathway and a fiber-dependent (secondary) pathway. We first show that the balance between primary and secondary contributions can be manipulated by an external interface. Specifically, in the presence of this interface, the primary mechanism dominates, whereas in its absence, the secondary mechanism dominates. Intriguingly, we determine that both the reaction order and the enthalpy of activation of the two nucleation processes are identical. We interrogate this coincidence by global analysis using a simplified model generally applicable to protein polymerization. A physically reasonable set of parameters can be found to satisfy the coincidence. We conclude that primary and secondary nucleation need not represent different processes for amyloid formation. Rather, they are alternative manifestations of the same, surface-catalyzed nucleation event.
A mutation in a chromosome condensin II subunit, kleisin β, specifically disrupts T cell development
Authors: Gosling Katharine M. , Makaroff Lydia E. , Theodoratos Angelo , Kim Yong-Hee , Whittle Belinda , Rui Lixin , Wu Hua , Hong Nancy A. , Kennedy Gavin C. , Fritz Julie-Anne , Yates Adele L. , Goodnow Christopher C. , Fahrer Aude M.
Published: July 2007

Condensins are ubiquitously expressed multiprotein complexes that are important for chromosome condensation and epigenetic regulation of gene transcription, but whose specific roles in vertebrates are poorly understood. We describe a mouse strain, nessy, isolated during an ethylnitrosourea screen for recessive immunological mutations. The nessy mouse has a defect in T lymphocyte development that decreases circulating T cell numbers, increases their expression of the activation/memory marker CD44, and dramatically decreases the numbers of CD4
+
CD8
+
thymocytes and their immediate DN4 precursors. A missense mutation in an unusual alternatively spliced first exon of the kleisin β gene, a member of the condensin II complex, was shown to be responsible and act in a T cell-autonomous manner. Despite the ubiquitous expression and role of condensins, kleisin β
nes/nes
mice were viable, fertile, and showed no defects even in the parallel pathway of B cell lymphocyte differentiation. These data define a unique lineage-specific requirement for kleisin β in mammalian T cell differentiation.
Inhibition of the cytokine response does not protect against lethal H5N1 influenza infection
Authors: Salomon Rachelle , Hoffmann Erich , Webster Robert G.
Published: July 2007

Because proinflammatory cytokines are markedly elevated during H5N1 influenza virus infection, the “cytokine storm” is hypothesized to be the main cause of mortality. Here, we demonstrate that mice deficient in the hallmark inflammatory cytokines TNF-α, IL-6, or CC chemokine ligand 2 succumb to infection with A/Vietnam/1203/04 (H5N1) virus, as do wild-type mice treated with glucocorticoids for suppression of cytokines. Because cytokine inhibition does not protect against death, therapies that target the virus rather than cytokines may be preferable.
The native language of social cognition
Authors: Kinzler Katherine D. , Dupoux Emmanuel , Spelke Elizabeth S.
Published: July 2007

What leads humans to divide the social world into groups, preferring their own group and disfavoring others? Experiments with infants and young children suggest these tendencies are based on predispositions that emerge early in life and depend, in part, on natural language. Young infants prefer to look at a person who previously spoke their native language. Older infants preferentially accept toys from native-language speakers, and preschool children preferentially select native-language speakers as friends. Variations in accent are sufficient to evoke these social preferences, which are observed in infants before they produce or comprehend speech and are exhibited by children even when they comprehend the foreign-accented speech. Early-developing preferences for native-language speakers may serve as a foundation for later-developing preferences and conflicts among social groups.
Modulation of human neural stem cell differentiation in Alzheimer (APP23) transgenic mice by phenserine
Authors: Marutle Amelia , Ohmitsu Masao , Nilbratt Mats , Greig Nigel H. , Nordberg Agneta , Sugaya Kiminobu
Published: July 2007

In a previous study, we found that human neural stem cells (HNSCs) exposed to high concentrations of secreted amyloid-precursor protein (sAPP)
in vitro
differentiated into mainly astrocytes, suggesting that pathological alterations in APP processing during neurodegenerative conditions such as Alzheimer's disease (AD) may prevent neuronal differentiation of HNSCs. Thus, successful neuroplacement therapy for AD may require regulating APP expression to favorable levels to enhance neuronal differentiation of HNSCs. Phenserine, a recently developed cholinesterase inhibitor (ChEI), has been reported to reduce APP levels
in vitro
and
in vivo
. In this study, we found reductions of APP and glial fibrillary acidic protein (GFAP) levels in the hippocampus of APP23 mice after 14 days treatment with (+)-phenserine (25 mg/kg) lacking ChEI activity. No significant change in APP gene expression was detected, suggesting that (+)-phenserine decreases APP levels and reactive astrocytes by posttranscription regulation. HNSCs transplanted into (+)-phenserine-treated APP23 mice followed by an additional 7 days of treatment with (+)-phenserine migrated and differentiated into neurons in the hippocampus and cortex after 6 weeks. Moreover, (+)-phenserine significantly increased neuronal differentiation of implanted HNSCs in hippocampal and cortical regions of APP23 mice and in the CA1 region of control mice. These results indicate that (+)-phenserine reduces APP protein
in vivo
and increases neuronal differentiation of HNSCs. Combination use of HNSC transplantation and treatment with drugs such as (+)-phenserine that modulate APP levels in the brain may be a useful tool for understanding mechanisms regulating stem cell migration and differentiation during neurodegenerative conditions in AD.