bluuebunny/crossref_metadata_2025 huggingface dataset:
Promoting Science‐based Approaches to Teen Pregnancy Prevention: Proactively Engaging the Three Systems of the Interactive Systems Framework
Authors: Lesesne Catherine A. , Lewis Kelly M. , White Carla Poindexter , Green Diane C. , Duffy Jennifer L. , Wandersman Abraham
Published: February 2008

In the field of teen pregnancy prevention many efficacious prevention programs are available but adoption of these programs is slow at the community level. In this article, we present a multi‐site, capacity‐building effort called the Promoting Science‐based Approaches to Teen Pregnancy Prevention project (PSBA) as a case example of a proactive application of the Interactive System Framework (ISF) for dissemination and implementation. The ISF is a multi‐system model leading to dissemination and implementation of science‐based prevention programming through the work of three interactive systems: The “Prevention Delivery,” “Prevention Support,” and “Prevention Synthesis & Translation” Systems. This article describes the proactive use of the ISF to conceptualize and bolster the PSBA program's goal of assisting local prevention partners in the use of science‐based approaches (SBA) to prevent teen pregnancy. PSBA uses all three systems of the ISF to facilitate practice improvements and offers valuable research opportunities to investigate factors related to dissemination and implementation processes across these systems. Describing our application of this framework highlights the feasibility of actively using the ISF to build prevention infrastructure and to guide large‐scale prevention promotion strategies in the area of teen pregnancy prevention. The program's ongoing evaluation is presented as an example of early efforts to develop an evidence base around the ISF. Research implications are discussed.
Peripheral blood gene expression profiling for cardiovascular disease assessment
Authors: Aziz Hamza , Zaas Aimee , Ginsburg Geoffrey S.
Published: February 2008

Whole blood gene expression profiling has the potential to be informative about dynamic changes in disease states and to provide information on underlying disease mechanisms. Having demonstrated proof of concept in animal models, a number of studies have now tried to tackle the complexity of cardiovascular disease in human hosts to develop better diagnostic and prognostic indicators. These studies show that genomic signatures are capable of classifying patients with cardiovascular diseases into finer categories based on the molecular architecture of a patient’s disease and more accurately predict the likelihood of a cardiovascular event than current techniques. To highlight the spectrum of potential applications of whole blood gene expression profiling approach in cardiovascular science, we have chosen to review the findings in a number of complex cardiovascular diseases such as atherosclerosis, hypertension and myocardial infarction as well as thromboembolism, aortic aneurysm, and heart transplant.
Pediatric supracondylar humerus fractures: Treatment by type of orthopedic surgeon
Authors: Farley Frances A. , Patel Prerana , Craig Clifford L. , Blakemore Laurel C. , Hensinger Robert N. , Zhang Lingling , Caird Michelle S.
Published: February 2008

Purpose

Outcomes in children with supracondylar humerus fractures were stratified by type of treating orthopedic surgeon: pediatric orthopedic surgeon and nonpediatric orthopedic surgeon.

Methods

The outcome factors in 444 children examined included: open reduction rate, complications, postoperative nerve injury, repinning rate, need for physical therapy, and residual nerve palsy at final follow-up.

Results

For the severe fractures, significantly more fractures were treated by open reduction in the pediatric orthopedic surgeon group than in the nonpediatric orthopedic surgeon group. There were no other significant differences in outcomes between the fractures treated by the pediatric orthopedic surgeons and nonpediatric orthopedic surgeons.

Conclusions

This study supports the assertion that both pediatric and nonpediatric orthopedic surgeons in an academic setting have sufficient training, skill, and experience to treat these common injuries.
W. Arthur Lewis in Retrospect
Authors: Becker Charles M. , Craigie Terry-Ann
Published: February 2008

This paper reviews several themes from the writings of W. Arthur Lewis, both the first black Nobel Laureate in Economics and the first from a developing country, and examines them from the perspective of two to five decades of hindsight. The paper emphasizes three main interrelated aspects; economic growth, economic dualism, and “the evolution of the economic order”—the forces that drive the prices of goods and relative incomes across countries. Lewis's messages still resonate today, as he foresaw the rise of industrial exports from developing countries—and also that it would not end the large gaps among nations’ standards of living. The paper both documents these rises and asks whether one could have predicted it from information available in the 1960s, or whether additional prescience was necessary.
Racial Differences in Civic Participation and Charitable Giving: The Confounding Effects of Educational Attainment and Unmeasured Ability
Authors: Brown Eleanor , Smart Rosanna
Published: February 2008

In this paper we use human capital theory to follow the links from educational attainment to civic engagement, and to other pro-social behaviors such as charitable giving and volunteering, and in so doing we offer a cautionary explanation for observed racial differences in civic participation, giving, and volunteering. Our argument is that when, in a racialized society such as the U.S., the costs and benefits of education differ by race, and when innate ability is an unmeasured source of heterogeneity across individuals, controlling for educational attainment and not for ability will create spurious race effects in empirical studies of behaviors that depend on both education and ability. Because (1) blacks at any level of educational attainment are predicted to be of higher average ability than equally educated whites and (2) higher ability is associated with higher levels of civic participation, a regression of civic participation on educational attainment and race will produce a positive coefficient on the dummy variable that takes on a value of one if the subject is African American. Using data from the Social Capital Community Benchmark Survey, we find strong support for the interpretation of race effects as spurious artifacts of having included data on educational attainment without measures of innate ability.
Infection pattern of the spirurid nematodeProtospirura numidica criceticolain the cricetid rodentAkodon azaraeon poultry farms of central Argentina
Authors: Miño M.H.
Published: February 2008

The nematodeProtospirura numidica criceticolainfects the stomach of Neotropical cricetid rodents when they ingest infected arthropods. In North America, prevalence values fluctuated, showing marked peaks in desert habitats, while remaining low in humid environments. The infection pattern has not been studied in South American rodents. In this work, yearly infection byP. n. criceticolawas analysed in the South American cricetidAkodon azaraeseasonally captured from July 1998 to July 2000 and in March 2001 on poultry farms of a humid region of Argentina. Seasonal occurrence of third- and fourth-stage larvae and adults was recorded. Seasonal population and community parameters of the parasite were calculated. The occurrence of larval stages was confirmed for the four seasons. Prevalence fluctuated between 0 and 36% and did not show a seasonal pattern. It was not related to the abundance ofA. azarae(rs = 0.37) or to rainfall. In this humid region of Argentina, where food resources are diverse throughout the year, the omnivorousA. azaraemay have a variable diet so that infection can occur in the four seasons. Prevalence values were not very high, in accordance with observations in humid habitats of North America. The infection was also characterized by low intensity, abundance and dominance. Only 3.8% of the rodents were parasitized with three or more specimens of the parasite, and that was only in autumn. It is suggested that rodents can not overwinter successfully with a heavy biomass of stomach parasites.
Mental disorders among persons with arthritis: results
from the World Mental Health Surveys
Authors: He Y. , Zhang M. , Lin E. H. B. , Bruffaerts R. , Posada-Villa J. , Angermeyer M. C. , Levinson D. , de Girolamo G. , Uda H. , Mneimneh Z. , Benjet C. , Graaf R. de , Scott K. M. , Gureje O. , Seedat S. , Haro J. M. , Bromet E. J. , Alonso J. , Kovess V. , von Korff M. , Kessler R.
Published: February 2008

Background

Prior studies in the USA have reported higher rates of mental disorders among
persons with arthritis but no cross-national studies have been conducted. In
this study the prevalence of specific mental disorders among persons with
arthritis was estimated and their association with arthritis across diverse
countries assessed.

Method

The study was a series of cross-sectional population sample surveys. Eighteen
population surveys of household-residing adults were carried out in 17
countries in different regions of the world. Most were carried out between
2001 and 2002, but others were completed as late as 2007. Mental disorders
were assessed with the World Health Organization (WHO)
World Mental Health–Composite International Diagnostic Interview
(WMH-CIDI). Arthritis was ascertained by self-report.
The association of anxiety disorders, mood disorders and alcohol use
disorders with arthritis was assessed, controlling for age and sex.
Prevalence rates for specific mental disorders among persons with and
without arthritis were calculated and odds ratios
(ORs) with 95% confidence intervals were
used to estimate the association.

Results

After adjusting for age and sex, specific mood and anxiety disorders occurred
among persons with arthritis at higher rates than among persons without
arthritis. Alcohol abuse/dependence showed a weaker and less
consistent association with arthritis. The pooled estimates of the age- and
sex-adjusted ORs were about 1.9 for mood disorders and for anxiety disorders
and about 1.5 for alcohol abuse/dependence among persons with
versus without arthritis. The pattern
of association between specific mood and anxiety disorders and arthritis was
similar across countries.

Conclusions

Mood and anxiety disorders occur with greater frequency among persons with
arthritis than those without arthritis across diverse countries. The
strength of association of specific mood and anxiety disorders with
arthritis was generally consistent across disorders and across
countries.
UNIFORM CONVERGENCE RATES FOR KERNEL ESTIMATION WITH DEPENDENT DATA
Authors: Hansen Bruce E.
Published: February 2008

This paper presents a set of rate of uniform consistency results for kernel estimators of density functions and regressions functions. We generalize the existing literature by allowing for stationary strong mixing multivariate data with infinite support, kernels with unbounded support, and general bandwidth sequences. These results are useful for semiparametric estimation based on a first-stage nonparametric estimator.
INTRODUCTION
Authors: Fowler William R.
Published: February 2008

In this issue we introduce a new, occasional feature in Ancient Mesoamerica: longer, sustained, detailed papers that elaborate the finer points of controversial culture-historical issues or theoretical debates in Mesoamerican studies. Each of these longer pieces will be followed in a future issue by invited commentaries. This first paper involves a debate that has been brewing for some time: the origins of the words for cacao (Theobroma cacao and congeners [McNeil 2006b:341]) and chocolate and the culture-historical implications. Few things of ancient Mesoamerica have whetted both the intellectual and the culinary appetite like cacao and and its derivative, chocolate. Cacao and chocolate, in fact, have represented many things in Mesoamerica and all over the world: food, beverage, commodity, money—and words that evoke lively scholarly debate.
POST-FIRE RESPROUTING AND MORTALITY IN CERRADO WOODY PLANT SPECIES OVER A THREE-YEAR PERIOD
Authors: Medeiros M. B. , Miranda H. S.
Published: February 2008

The objective of this work was to evaluate resprouting features and mortality in Cerrado woody plants after annual controlled fires (in 1998, 1999 and 2000) in a campo sujo area (an open savanna physiognomy) of 2500 m2 at the Reserva Ecológica do IBGE, Brasília-DF, Brazil. The area was protected against fire for 23 years prior to the fires. All plants of the woody layer with diameter larger than 2.0 cm at 30 cm from soil level were tagged and identified. At about one year after each controlled fire the damage type and the number of basal and underground sprouts for each individual were recorded. Stem diameter and height were measured for each marked sprout. A total of 1307 sprouts were tagged and measured. The main impact of fire on resprouting was a decrease in the number of new sprouts after each controlled fire: 684 sprouts after the first burning to 248 after the third burning. Mortality of sprouts was 34.8% and 37.8% after the 1999 and 2000 fires. A decrease in the number of sprouts with a diameter smaller than 1.0 cm after the successive fires was also observed, indicating that fires at one-year intervals resulted in alterations in the structure of the woody vegetation in the area. The species mortality rates were higher after the first controlled fire. However, it seems that there is no relation between sprouting capacity and species survival. The species that show mortality rates lower than 10% also showed a variety of sprouting capacity.
IMPATIENS PACHYCAULON (BALSAMINACEAE), A NEW SPECIES FROM LAOS
Authors: Newman M. F.
Published: February 2008

A new species of Impatiens (Balsaminaceae), Impatiens pachycaulon M.F.Newman, is described and illustrated.
A NEW SPECIES OF AGALMYLA (GESNERIACEAE) FROM SULAWESI
Authors: Middleton D. J. , Scott S. M.
Published: February 2008

A new species of Gesneriaceae from Sulawesi, Agalmyla hilliardiae D.J.Middleton & S.Scott in Agalmyla sect. Exannularia, is described and illustrated.
Flora Malesiana, Series I. Volume 18. Apocynaceae (subfamilies Rauvolfioideae and Apocynoideae). D. J. Middleton.
Authors: Goyder D.
Published: February 2008

..
Cleaning and sterilisation of infant feeding equipment: a systematic review
Authors: Renfrew Mary J , McLoughlin Marie , McFadden Alison
Published: February 2008

Aim

To assess the clinical and cost-effectiveness of different methods of cleaning and sterilisation of infant feeding equipment used in the home.

Design

Systematic review of studies from developed countries on the effectiveness of methods of cleaning and sterilisation of infant feeding equipment used in the home. A brief telephone survey of UK-based manufacturers of infant feeding equipment and formula to ascertain the evidence base used for their recommendations, and a comparison of current relevant guidelines in developed countries, informed the work.

Results

National guidelines from six countries demonstrated variation and lack of evidence to support current guidance. Manufacturers did not report evidence of effectiveness to support their recommendations. Nine studies were identified; eight conducted between 1962 and 1985 and one in 1997. All had methodological weaknesses. Hand-washing was identified as fundamentally important. Health professionals were reported as not providing appropriate education on the importance and methods of cleaning and sterilisation. Mothers of subsequent babies and women from lower socio-economic groups were less likely to follow recommended procedures.

Conclusion

There is a lack of good-quality evidence on effective ways of cleaning and sterilising infant feeding equipment in the home. The evidence base does not answer the question about which of the methods in common use is most effective or most likely to be used by parents. Hand-washing before handling feeding equipment remains important. Further research on the range of methods used in the home environment, including assessment of the views of parents and carers, is required.
TCHR: a framework for tabled CLP
Authors: SCHRIJVERS TOM , DEMOEN BART , WARREN DAVID S.
Published: February 2008

Tabled Constraint Logic Programming is a powerful execution mechanism for dealing with Constraint Logic Programming without worrying about fixpoint computation. Various applications, e.g. in the fields of program analysis and model checking, have been proposed. Unfortunately, a high-level system for developing new applications is lacking, and programmers are forced to resort to complicated ad hoc solutions.

This papers presents TCHR, a high-level framework for tabled Constraint Logic Programming. It integrates in a light-weight manner Constraint Handling Rules (CHR), a high-level language for constraint solvers, with tabled Logic Programming. The framework is easily instantiated with new application-specific constraint domains. Various high-level operations can be instantiated to control performance. In particular, we propose a novel, generalized technique for compacting answer sets.
Deep ocean inertia‐gravity waves simulated in a high‐resolution global coupled atmosphere–ocean GCM
Authors: Komori Nobumasa , Ohfuchi Wataru , Taguchi Bunmei , Sasaki Hideharu , Klein Patrice
Published: February 2008

In order to investigate the deep ocean inertia‐gravity waves, a high‐resolution global coupled atmosphere–ocean simulation is carried out with a coupling interval of 20 minutes. Large (∼10−3 m s−1) root‐mean‐square variability of vertical velocity is found in middepths (2000–4000 m), which is not reported in previous studies using realistic ocean simulations. Horizontal distribution of the large variability roughly corresponds to the wintertime atmospheric storm tracks and is stretched equatorward due to β‐dispersion in open ocean with some “shadow regions” behind the obstacles. Frequency spectrum of vertical velocity has strong peaks at around f and 2f (f is the local inertial period) in midlatitudes, and has additional peak at around (3/2)f or 3f at some points. These results suggest necessity of re‐evaluation of wind‐induced near‐inertial energy with high‐frequency atmospheric forcing.
Characteristics of atmospheric gravity wave activity in the polar regions revealed by GPS radio occultation data with CHAMP
Authors: Hei Hayato , Tsuda Toshitaka , Hirooka Toshihiko
Published: February 2008

Using GPS radio occultation data during 2001–2005, we studied the climatological behavior of atmospheric gravity waves in the polar stratosphere. We calculated temperature fluctuations with vertical wavelengths shorter than 7 km and then determined the wave potential energy, Ep, every month in a longitude‐latitude cell of 20° × 10° between 12 km and 33 km. In the Arctic region (50–90°N), Ep shows an annual variation with maximum in winter, consistent with the zonal mean horizontal wind, V, and the Eliassen‐Palm (E‐P) flux, Fz. The large Fz values indicate higher planetary wave activity, resulting in distortion of the polar vortex. The unbalanced flow can then excite gravity waves through geostrophic adjustment. In the Antarctic region (50–90°S), Ep gradually increases during winter and reaches its maximum in spring before decreasing rapidly. The time derivative of V coincides with the Ep peak and the horizontal distribution of Ep has a similar structure to V, suggesting that the Ep enhancement is closely related to the decay of the polar vortex. During major warming events over the Arctic, the divergence of E‐P flux, ΔF, was enhanced, coinciding with large Ep. In the Antarctic, ΔF strongly correlates with Ep in spring. Gravity waves seem to be effectively generated through planetary wave transience and/or breaking. Orographic generation of gravity waves seems to be important in limited areas only, such as Scandinavia and the Antarctic Peninsula, showing that it is less important than the polar night jet in determining the climatological behavior of gravity waves.
Chemical speciation of sulfur in marine cloud droplets and particles: Analysis of individual particles from the marine boundary layer over the California current
Authors: Hopkins Rebecca J. , Desyaterik Yury , Tivanski Alexei V. , Zaveri Rahul A. , Berkowitz Carl M. , Tyliszczak Tolek , Gilles Mary K. , Laskin Alexander
Published: February 2008

Detailed chemical speciation of the dry residue particles from individual cloud droplets and interstitial aerosol collected during the Marine Stratus Experiment (MASE) was performed using a combination of complementary microanalysis techniques. Techniques include computer controlled scanning electron microscopy with energy dispersed analysis of X rays (CCSEM/EDX), time‐of‐flight secondary ionization mass spectrometry (TOF‐SIMS), and scanning transmission X‐ray microscopy with near edge X‐ray absorption fine structure spectroscopy (STXM/NEXAFS). Samples were collected at the ground site located in Point Reyes National Seashore, approximately 1 km from the coast. This manuscript focuses on the analysis of individual particles sampled from air masses that originated over the open ocean and then passed through the area of the California current located along the northern California coast. On the basis of composition, morphology, and chemical bonding information, two externally mixed, distinct classes of sulfur containing particles were identified: chemically modified (aged) sea salt particles and secondary formed sulfate particles. The results indicate substantial heterogeneous replacement of chloride by methanesulfonate (CH3SO3−) and non‐sea‐salt sulfate (nss‐SO42−) in sea‐salt particles with characteristic ratios of nss‐S/Na > 0.10 and CH3SO3−/nss‐SO42− > 0.6.
Amino‐acid sequence motifs for PKC‐mediated membrane trafficking of the inhibitory killer Ig‐like receptor
Authors: Chwae Yong‐Joon , Lee Jae Myun , Kim Hyung‐Ran , Kim Eun Joo , Lee Seung Tae , Soh Jae‐Won , Kim Jongsun
Published: February 2008

Activation‐induced upregulation of inhibitory killer Ig‐like receptor (KIR) is regulated by protein kinase Cs (PKCs). Conventional PKCs increase KIR expression on the post‐transcriptional level by increasing the recycling of surface molecules and endoplasmic reticulum (ER)–Golgi processing. PKCδ plays a role in the secretion of cytoplasmic KIR through lytic granules. In this study, we identified amino acid sequence motifs associated with PKC‐mediated KIR membrane trafficking by systematic mutagenesis. Mutations of Y398 and HLWC364 completely inhibited the PMA‐induced increase of KIR molecules at surface as well as total protein levels, indicating that these are associated with ER–Golgi processing and sorting to plasma membrane through lytic granules. Mutations of Y‐based motif, including Y398, acidic region (PE394), dileucine motif‐like region (IL423) and PKC‐phosphorylatable S415 caused a blockade of surface KIR endocytosis after PKC stimulation. Mutation of T145 caused an accumulation of mutant proteins in late endosomes and lysosomes after PKC activation, suggesting that T145 might be related to the recovery of endocytosed KIR to the surface membrane. We also demonstrated that PKCs could directly phosphorylate the KIR cytoplasmic tail by means of western blot and in vitro kinase assay, implying that phosphorylation status of KIR cytoplasmic tail can direct the fate of surface KIR molecules. Taken together, various sequence motifs are implicated in the PKC‐mediated post‐transcriptional upregulation of KIR, and each of these motifs work in different steps after PKC activation.
A discussion on the application and production of metal ion beams
Authors: Ren Xiaotang , Zhao Ziqiang , Zhao Weijiang
Published: February 2008

Metal ion beams, which are used in surface modification of metals and alloys as ion beam micrometallurgy, are promising candidates for advanced applications in semiconductors and insulators. Doping with transition metal and rare-earth metal ions in semiconductors and insulators to form metallic nanoclusters attracted much more attention recently, since their applications in diluted magnetic semiconductors, electroluminescent devices, giant magnetic resistance, etc. In this paper, some experiments for metal ion beams will be presented, and various methods and technologies for the production of metal ion beams will be discussed.
Development of a MeV proton beam irradiation system
Authors: Park Bum-Sik , Cho Yong-Sub , Hong In-Seok
Published: February 2008

A proton beam irradiation system for the application of the MeV class proton beam, such as an implantation for a power semiconductor device and a smart-cut technology for a semiconductor production process, has been developed. This system consists of a negative ion source, an Einzel lens for a low energy beam transport, accelerating tubes, a gas stripper, a Cockroft-Walton high voltage power supply with 1MV, a vacuum pumping system, and a high pressure insulating gas system. The negative hydrogen ion source is based on TRIUMF’s design. Following the tandem accelerator, a pair of magnets is installed for raster scanning of the MeV proton beam to obtain a uniform irradiation pattern on the target. The system is 7m long from the ion source to the target and is optimized for the proton beam irradiation. The details of the system development will be described.
Electron cyclotron resonance 140mA D+ beam extraction optimization for IFMIF EVEDA accelerator
Authors: Delferrière O. , De Menezes D. , Gobin R. , Harrault F. , Tuske O.
Published: February 2008

Based on the experience of the SILHI electron cyclotron resonance (ECR) ion source for the IPHI accelerator, which produces routinely 100–120mA H+ beam, the CEA-Saclay is in charge of the design and realization of the 140mA cw deuteron source for the IFMIF project (International Fusion Materials Irradiation Facility). IFMIF is an accelerator-based neutron irradiation facility consisting of two accelerators of 125mA D+ beam at 40MeV that hit in parallel a lithium target. IFMIF utilizes the deuteron-lithium (d-Li) neutron, producing a reaction to simulate the 14MeV neutron environment in deuterium-tritium (D-T) fusion reactors. In the framework of the IFMIF EVEDA phase (Engineering Validation and Engineering Design Activities), we are studying a cw ECR ion source with a new extraction system to allow high current extraction while keeping a low divergence as well as a small emittance. Starting from SILHI five-electrode system with H+ ions, the extracted beam characteristics as well as electric field conditions are compared with the cases of four- and three-electrode extraction systems. Experimental results made on the SILHI source with H+ ions are briefly discussed. Extensive experimental results on the new source test bench BETSI are expected as soon as the design and fabrication of a dedicated extraction system with a new set of electrodes will be finished.
Extreme ultraviolet narrow band emission from electron cyclotron resonance plasmas
Authors: Zhao H. Y. , Zhao H. W. , Sun L. T. , Zhang X. Z. , Wang H. , Ma B. H. , Li X. X. , Zhu Y. H. , Sheng L. S. , Zhang G. B. , Tian Y. C.
Published: February 2008

Extreme ultraviolet lithography (EUVL) is considered as the most promising solution at and below dynamic random access memory 32nm half pitch among the next generation lithography, and EUV light sources with high output power and sufficient lifetime are crucial for the realization of EUVL. However, there is no EUV light source completely meeting the requirements for the commercial application in lithography yet. Therefore, ECR plasma is proposed as a novel concept EUV light source. In order to investigate the feasibility of ECR plasma as a EUV light source, the narrow band EUV power around 13.5nm emitted by two highly charged ECR ion sources—LECR2M and SECRAL—was measured with a calibrated EUV power measurement tool. Since the emission lines around 13.5nm can be attributed to the 4d-5p transitions of Xe XI or the 4d-4f unresolved transition array of Sn VIII-XIII, xenon plasma was investigated. The dependence of the EUV throughput and the corresponding conversion efficiency on the parameters of the ion source, such as the rf power and the magnetic confinement configurations, were preliminarily studied.
Effects of fundamental and second harmonic electron cyclotron resonances on ECRIS
Authors: Kato Yushi , Satani Takashi , Asaji Toyohisa , Sato Fuminobu , Iida Toshiyuki
Published: February 2008

A new concept on magnetic field of plasma production and confinement has been proposed to enhance efficiency of an electron cyclotron resonance (ECR) plasma for broad and dense ion beam source under the low pressure. The magnetic field configuration is constructed by a pair of comb-shaped magnet which has opposite polarity to each other, and which cylindrically surrounds the plasma chamber. This magnetic configuration suppresses the loss due to E×B drift, and then plasma confinement is enhanced. The profiles of the electron temperature and density are measured around the ECR zones of the fundamentals and the second harmonics for 2.45GHz and 11–13GHz microwaves by using Langmuir probe. Their characteristics and effects are clarified under various operating conditions in both of simple multipole and comb-shaped magnetic configurations.
Importance of electric field for H− extraction in a volume-type hydrogen negative ion source
Authors: Matsumoto Y. , Nishiura M. , Sasao M. , Yamaoka H. , Shinto K. , Wada M.
Published: February 2008

The effect upon extraction of negative hydrogen ions (H−) due to electric field near the extractor hole of a H− source is studied experimentally and theoretically. Probe measurements show that the extraction electric field penetrates into the plasma in the region near the extractor hole. Based on this observation a three-dimensional H− trajectory calculation that takes into account the local electric field distribution near the plasma electrode has been carried out. The validity of the trajectory calculation was examined by comparing the results with experimentally measured changes in H− current detected by a Faraday cup due to irradiation of a pulse laser beam in the region close to the extractor hole. The calculation results qualitatively explain the changes in H− current observed in the experiment. The calculation results also predict that the amount of H− current passing through the extractor hole changes with the electric field: the penetration of the electric field substantially enhances the H− extraction current, because it produces an electric field to attract H− toward the extraction hole.
Simulation studies on the evolution of gallium nitride on a liquid gallium surface under plasma bombardment
Authors: Vasquez M. R. , Flauta R. E. , Wada M.
Published: February 2008

Monte Carlo simulations were conducted to study the formation of gallium-nitride (GaN) layer on liquid gallium (Ga) sputtering target immersed in nitrogen (N2) plasma. In the simulation model, N ions were assumed to possess energy equal to the bias voltage applied to the sputtering target with respect to the plasma. The results showed the surface morphology of GaN changed from a relatively smooth GaN on Ga surface at 50eV N ion energy to a rough surface with GaN dendrites on liquid Ga at 500eV ion energy. Further increase in N ion energy up to 1keV resulted in smaller density of GaN dendrites on surface. Increasing surface coverage of Ga by GaN substantially reduced the sputtering yield of Ga from the target. These simulation results were correlated with previously reported experimental observations on liquid Ga surface immersed in the nitrogen plasma of a plasma-sputter-type ion source.
Bernas ion source discharge simulation
Authors: Roudskoy I. , Kulevoy T. V. , Petrenko S. V. , Kuibeda R. P. , Seleznev D. N. , Pershin V. I. , Hershcovitch A. , Johnson B. M. , Gushenets V. I. , Oks E. M. , Poole H. P.
Published: February 2008

As the technology and applications continue to grow up, the development of plasma and ion sources with clearly specified characteristic is required. Therefore comprehensive numerical studies at the project stage are the key point for ion implantation source manufacturing (especially for low energy implantation). Recently the most commonly encountered numerical approach is the Monte Carlo particle-in-cell (MCPIC) method also known as particle-in-cell method with Monte Carlo collisions. In ITEP the 2D3V numerical code PICSIS-2D realizing MCPIC method was developed in the framework of the joint research program. We present first results of the simulation for several materials interested in semiconductors. These results are compared with experimental data obtained at the ITEP ion source test bench.
Acetylene-vinylidene isomerization in ultrashort intense laser fields studied by triple ion-coincidence momentum imaging
Authors: Hishikawa Akiyoshi , Matsuda Akitaka , Takahashi Eiji J. , Fushitani Mizuho
Published: February 2008

The isomerization of acetylene via hydrogen migration in intense laser fields (8×1014W∕cm2) has been investigated by coincidence momentum imaging of the three-body Coulomb explosion process, C2H23+→H++C++CH+. When ultrashort (9fs) laser pulses are used, the angle between the momenta of C+ and H+ fragments exhibits a sharp distribution peaked at a small angle (∼20°), showing that the hydrogen atom remains near the original carbon site in the acetylene configuration. On the other hand, a significantly broad distribution extending to larger momentum angles (∼120°) is observed when the pulse duration is increased to 35fs, indicating that the ultrafast isomerization to vinylidene is induced in the longer laser pulse.
Block copolymers confined in a nanopore: Pathfinding in a curving and frustrating flatland
Authors: Sevink G. J. A. , Zvelindovsky A. V.
Published: February 2008

We have studied structure formation in a confined block copolymer melt by means of dynamic density functional theory. The confinement is two dimensional, and the confined geometry is that of a cylindrical nanopore. Although the results of this study are general, our coarse-grained molecular model is inspired by an experimental lamella-forming polysterene-polybutadiene diblock copolymer system [K. Shin et al., Science 306, 76 (2004)], in which an exotic toroidal structure was observed upon confinement in alumina nanopores. Our computational study shows that a zoo of exotic structures can be formed, although the majority, including the catenoid, helix, and double helix that were also found in Monte Carlo nanopore studies, are metastable states. We introduce a general classification scheme and consider the role of kinetics and elongational pressure on stability and formation pathway of both equilibrium and metastable structures in detail. We find that helicity and threefold connections mediate structural transitions on a larger scale. Moreover, by matching the remaining parameter in our mesoscopic method, the Flory-Huggins parameter χ, to the experimental system, we obtain a structure that resembles the experimental toroidal structure in great detail. Here, the most important factor seems to be the roughness of the pore, i.e., small variations of the pore radius on a scale that is larger than the characteristic size in the system.
Multiply charged carbon-ion production for medical application
Authors: Kitagawa A. , Muramatsu M. , Sasaki N. , Takasugi W. , Wakaisami S. , Biri S. , Drentje A. G.
Published: February 2008

Over 3000 cancer patients have already been treated by the heavy-ion medical accelerator in Chiba at the National Institute of Radiological Sciences since 1994. The clinical results have clearly verified the effectiveness and safety of heavy-ion radiotherapy. The most important result has been to establish that the carbon ion is one of the most effective radiations for radiotherapy. The ion source is required to realize a stable beam with the same conditions for daily operation. However, the deposition of carbon ions on the wall of the plasma chamber is normally unavoidable. This causes an “anti-wall-coating effect,” i.e., a decreasing of the beam, especially for the higher charge-state ions due to the surface material of the wall. The ion source must be required to produce a sufficiently intense beam under the bad condition. Other problems were solved by improvements and maintenance, and thus we obtained enough reproducibility and stability along with decreased failures. We summarize our over 13years of experience, and show the scope for further developments.
Further characterization of oxygen vacancies and zinc vacancies in electron-irradiated ZnO
Authors: Evans S. M. , Giles N. C. , Halliburton L. E. , Kappers L. A.
Published: February 2008

Electron paramagnetic resonance (EPR) has been used to monitor oxygen vacancies and zinc vacancies in a ZnO crystal irradiated near room temperature with 1.5MeV electrons. Out-of-phase detection at 30K greatly enhances the EPR signals from these vacancies. Following the electron irradiation, but before illumination, Fe3+ ions and nonaxial singly ionized zinc vacancies are observed. Illumination with 325nm laser light at low temperature eliminates the Fe3+ signal while producing spectra from singly ionized oxygen vacancies, neutral zinc vacancies, and axial singly ionized zinc vacancies. This light also produces EPR spectra from zinc vacancies having a OH− ion at an adjacent oxygen site. The low-temperature response of the irradiated crystal to illumination wavelengths between 350 and 750nm is described. Wavelengths shorter than 600nm convert Fe3+ ions to Fe2+ ions and convert neutral oxygen vacancies to singly ionized oxygen vacancies. Neutral zinc vacancies are formed by wavelengths shorter than 500nm as electrons are removed from isolated singly ionized zinc vacancies. Warming above 120K in the dark reverses the effect of the illuminations. These wavelength-dependence results suggest that the ground state of the neutral oxygen vacancy is deep, approximately 1.3eV above the valence band, and that the ground state of the singly ionized zinc vacancy is also deep, about 0.9eV above the valence band.
Distortion of magnetic field and magnetic force of a brushless dc motor due to deformed rubber magnet
Authors: Lee C. J. , Jang G. H.
Published: February 2008

This paper investigates the distortion of magnetic field of a brushless dc (BLDC) motor due to deformed rubber magnet. Global or local deformation of rubber magnet in the BLDC motor is mathematically modeled by using the Fourier series. Distorted magnetic field is calculated by using the finite element method, and unbalanced magnetic force is calculated by using the Maxwell stress tensor. When the rubber magnet is globally or locally deformed, the unbalanced magnetic force has the frequencies with the first harmonic and the harmonics of slot number ±1. However, the harmonic deformation with multiple of common divisor of pole and slot does not generate unbalanced magnetic force due to the rotational symmetry.
Feasibility study of a laser ion source for primary ion injection into the Relativistic Heavy Ion Collider electron beam ion source
Authors: Kanesue Takeshi , Tamura Jun , Okamura Masahiro
Published: February 2008

Charge state 1+ions are required as a primary ion source for Relativistic Heavy Ion Collider-electron beam ion source (RHIC-EBIS) at BNL and laser ion source (LIS) is a candidate as one of the external ion source since low energy and low charge state ions can be generated by lower power density laser irradiation onto solid target surface. Plasma properties of Al27, Fe56, and Ta181 using the second harmonics of Nd:yttrium aluminum garnet laser (0.73J∕5.5ns and 532nm wavelength) for low charge state ion generation was measured. Charge state distribution of Ta was optimized for 1+with estimated laser power density of 9.1×108W∕cm2 on the target. It has been shown that the LIS can produce sufficient ion charge with the appropriate pulse structure to satisfy injection requirements of the RHIC EBIS.
Magnetization reversal process and bistability of Co∕Pt multilayer dot
Authors: Kikuchi N. , Kato T. , Okamoto S. , Kitakami O. , Tezuka N. , Sugimoto S.
Published: February 2008

Magnetization reversal process and the critical diameter dc for single and multidomain of Co∕Pt multilayer dot were investigated by detecting anomalous Hall effect of a single dot with diameter d ranging from 100to1000nm. The perpendicular anisotropy constant Ku was varied from 1.3×107to2.6×107erg∕cc by changing the Co layer thickness. The dominant magnetization process for the dots with d⩾1000nm was domain wall displacement, while nucleation of a reversed embryo governed the reversals in the dots smaller than 500nm. The dc for stable single domain increases with Ku from 150nm to larger than 1000nm. This behavior is mainly due to the increase of domain wall energy owing to the increase of Ku, and the dc coincides very well with the domain size of continuous films.
Global existence of spherically symmetric solutions for nonlinear compressible Navier–Stokes equations
Authors: Qin Yuming , Wen Shenglan
Published: February 2008

This paper concerns the global existence of solutions in Hi(i=1,2,4) for the nonlinear compressible Navier–Stokes equations of an initial-boundary value problem with an external force and a heat source. Some important inequalities are used and some new results are obtained.
Soft-magnetic materials characterized using a superconducting solenoid as magnetic source
Authors: Mastrogiacomo Giovanni , Löffler Jörg F. , Dilley Neil R.
Published: February 2008

Magnetization measurements of soft-magnetic materials can be affected if they are characterized using a superconducting solenoid. Recording hysteresis loops while stepping the magnetic field can cause an apparently inverted hysteresis, if due to the pinned remanent flux in the magnet the field at the sample location exceeds the sample’s coercive field. Hysteresis loops recorded while sweeping the field can also be affected by ramping rate. The sweeping-rate dependence is caused by leakage currents resulting from the persistent switch and synchronization issues regarding collection of magnetic moment and field data. The resulting errors can be estimated by measuring paramagnetic dysprosium oxide.
Turbulent transport coefficients and residual energy in mean-field dynamo theory
Authors: Hamba Fujihiro , Sato Hisanori
Published: February 2008

The turbulent electromotive force in the mean-field equation needs to be modeled to predict a large-scale magnetic field in magnetohydrodynamic turbulence at high Reynolds number. Using a statistical theory for inhomogeneous turbulence, model expressions for transport coefficients appearing in the turbulent electromotive force are derived including the α coefficient and the turbulent diffusivity. In particular, as one of the dynamo effects, the pumping effect is investigated and a model expression for the pumping term is obtained. It is shown that the pumping velocity is closely related to the gradient of the turbulent residual energy, or the difference between the turbulent kinetic and magnetic energies. The production terms in the transport equation for the turbulent electromotive force are also examined and the validity of the model expression is assessed by comparing with earlier results concerning the isotropic α coefficient. The mean magnetic field in a rotating spherical shell is calculated using a turbulence model to demonstrate the pumping effect.
Effects of dislocations on electron transport in wurtzite InN
Authors: Yu Xin-Gang , Liang Xin-Gang
Published: February 2008

A semiclassical three-valley Monte Carlo simulation approach was used to investigate electron transport in bulk InN using a revised set of material parameters. The simulation accounted for acoustic phonons, polar optical phonons, ionized impurities, and piezoelectric and dislocation scattering. The main emphasis is to analyze the effect of dislocations on the electron drift velocity and drift mobility. At low electric field strengths, dislocations have a significant impact on the steady and transient electron drift velocities. However, at high electric field strengths, the effects of dislocations on the drift velocity can be neglected. The electron mobility in InN with structural defects has a critical dislocation density below which dislocations have no effect on the mobility and beyond which the increased dislocation density results in an order-of-magnitude decrease in the electron mobility in InN.
Ponderomotive scattering of electrons and its application to measure the pulse duration of ultrafast electron beams
Authors: Liu Yunquan , Zhang Jie , Wu Huichun , Sheng Zhengming
Published: February 2008

We numerically study the relativistic ponderomotive scattering of an ultrafast electron beam with a focused high-intensity laser pulse using a three-dimensional test-particle code. The temporal evolution of the spatial distribution and the energy spectrum of the scattered electron beam are investigated. The method using the ponderomotive scattering effect to measure the pulse duration of an ultrashort electron beam is discussed in detail. Taking into account the group velocity mismatch, the interaction geometry, and electron energy spectrum modified by the ponderomotive forces, the pulse duration of ultrashort electron beams can be retrieved by the ponderomotive scattering cross-correlation method.
Improved thermal management of mid-IR quantum cascade lasers
Authors: Spagnolo Vincenzo , Lops Antonia , Scamarcio Gaetano , Vitiello Miriam S. , Di Franco Cinzia
Published: February 2008

We compared the thermal performance of mid-IR GaInAs∕AlInAs quantum cascade lasers (QCLs) having identical gain medium, but different heat sinking configurations. By using a two-dimensional anisotropic thermal model, we have calculated the temperature profiles and the heat flow patterns of ridge waveguide QCLs, either buried or planarized, and mounted substrate-side or epilayer-side down. Device planarization with Y2O3:Si3N4 dielectric layers gives an ∼7% reduction of the device thermal resistance with respect to InP buried heterostructures. If this planarization is combined with thick gold electroplating and epilayer-side mounting of the device, the thermal resistance is reduced by ∼34% and ∼50%, respectively, with respect to conventional ridge waveguide structures.
Hole mobility of 1-NaphDATA
Authors: Weiß Oliver J. , Krause Ralf K. , Hunze Arvid
Published: February 2008

The field-dependent hole mobility of 4,4′,4″-tris(1-naphthylphenylamino)triphenylamine (1-NaphDATA) has been measured on hole-only samples with layer thicknesses between 100 and 500 nm. To determine the mobility we employed three different methods: steady-state space-charge limited currents (SCLC), transient dark injection SCL currents (DI-SCLC), and admittance spectroscopy (AS). The results, especially the field dependence of the mobility, depend on the measuring method. The SCLC mobility increases with the layer thickness and becomes constant above 200 nm, which indicates a transition from contact-limited to bulk-limited conduction. Compared to AS and SCLC we found that DI-SCLC is the most reliable method to measure the mobility on thin samples because it is hardly affected by carrier trapping nor by the layer thickness. Using DI-SCLC an organic layer of 200 nm was sufficient to determine the bulk hole mobility of 1-NaphDATA (μ0=6.57×10−6 cm2/V s and γ=2.74×10−3 (cm/V)1/2, which is very thin compared to time-of-flight samples whose thickness is in the range of micrometers.
Spectroscopic study of microwave-enhanced silicon exfoliation
Authors: Thompson D. C. , Alford T. L. , Mayer J. W.
Published: February 2008

Infrared spectroscopy and Rutherford backscattering spectrometry are used to study the effect of microwaves on hydrogen implanted silicon. Infrared spectra demonstrate that the hydride species formed in hydrogen implant and microwave annealed silicon result in exfoliation in a manner similar to that in conductively annealed samples. The infrared spectra of microwave annealed samples reveal an increase in internal surface formation prior to exfoliation. This increase in internal surface formation demonstrates how microwave anneals can decrease the incubation time required prior to exfoliation. Rutherford backscattering and infrared spectra are presented to elucidate the minimized impact of the microwave effect in boron-hydrogen coimplanted silicon.