bluuebunny/crossref_metadata_2025 huggingface dataset:
A narrow band, green‐red colour centre laser in LiF fabricated by femtosecond laser pulses
Authors: Kurobori T. , Sakai T. , Aoshima S.
Published: March 2007

Recent advances in high‐intensity femtosecond (fs) laser pulses have made it possible to encode non‐erasable functional micro‐structures inside almost any type of photo‐insensitive transparent materials. We focus our attention on bulk lithium fluoride (LiF) because of its broad emission band from the green‐to‐red spectral range under excitation of a single absorption band at about 450 nm. Here a room temperature, visible laser action in LiF from a distributed‐feedback laser with embedded fine‐pitched gratings written by fs pulses and from a laser‐active colour centre laser with multilayer dielectric mirrors has been demonstrated. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Energy transfer and charge carrier capture processes in wide‐band‐gap scintillators
Authors: Nikl M. , Laguta V. V. , Vedda A.
Published: March 2007

Electron and hole trapping phenomena below room temperature were studied by simultaneous use of electron paramagnetic resonance (EPR) and thermostimulated luminescence (TSL) experiments in Ce‐doped YAlO3, Y3Al5O12 and Lu3Al5O12 single crystals. Charge‐carrier trapping associated with O– centers and antisite Y(Lu)Al defects in perovskite and garnet structures, respectively, was evidenced by EPR and associated with the dominant TSL peaks. Existence of F+ centers was proved by EPR in YAlO3. A Ce3+ ion at the Al site and spatially correlated CeLu and LuAl centers were evidenced in Lu3Al5O12 by the same method. Spatial correlation of the latter two centers is further supported by the associated tunneling‐driven radiative recombination process evidenced by phosphorescence decay. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Characterization of deep levels at GaAs/GaAs and GaAs/InAs interfaces grown by MBE‐interrupted growth technique
Authors: Kaniewska M. , Engström O. , Pacholak‐Cybulska M. , Sadeghi M.
Published: March 2007

In order to find the origin of crystalline defects occurring in the preparation of InAs/GaAs quantum dots (QDs), their appearance was tracked through three different sample types designed as Schottky diodes. Specimens with a GaAs cap layer on a GaAs buffer layer as well as with an InAs wetting layer without QDs were grown by molecular beam epitaxy (MBE) using the interrupted growth technique. Deep level transient spectroscopy (DLTS) was used for comparison with structures containing InAs QDs. It was found that two main levels with thermal activation energies of 0.14–0.16 eV and 0.46–0.52 eV from the conduction band edge, respectively, are grown‐in defects, which are characteristic of the growth interrupted interface occuring under an excess of As. Both these levels together with an additional level at 0.10–0.12 eV found in the InAs wetting layer structures were also present in those with QDs, probably resulting from strain or In penetration. All three defects were agglomerated close to the interface created by the interrupted growth. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Feature Article: Recent developments in micromachining of fused silica and quartz using excimer lasers
Authors: Tseng Ampere A.
Published: March 2007

This issue's Feature Article reports on the current achievements of structuring fused silica and crystal quartz materials on the micrometer scale by excimer laser ablation techniques [1]. It discusses the characteristics of direct ablation as well as the more specialized methods of laser‐induced backside wet etching and laser‐induced plasma‐assisted ablation. As an example of such high‐precision, high‐quality structures, the cover picture shows a set of scanning electron microscopy images of the morphologies of different patterns ablated on quartz substrates by an ArF excimer laser. These micro‐structures were ablated using the 193 nm line of an excimer laser at a fluence of 3.4 J/cm2 with 100 pulse shots. The cover picture was contributed by Ying‐Tung Chen, Chung Cheng Institute of Technology (Taiwan).

The Feature Article is authored by Ampere A. Tseng, who is a professor at the Department of Mechanical and Aerospace Engineering of Arizona State University. His main research interests lie with micro‐ and nanofabrication of various devices and systems.

The issue also includes an Editor's Choice article presenting experimental results on laser‐assisted debonding of GaN high electron mobility transistors [2]. The authors show how the laser‐assisted debonding process can be accomplished without compromising the electrical device characteristics or the material defect density.
Preparation of Ferrocene Nanocrystals by the Ultrasonic‐Solvent‐Substitution Method and Their Electrochemical Properties
Authors: Chen Ping , Wu Qing‐Sheng , Ding Ya‐Ping
Published: March 2007

Ferrocene nanocrystals are successfully prepared by the ultrasonic‐solvent‐substitution method. Transmission electron microscopy images show that the average diameter of the nanocrystals is about (40±5)nm and X‐ray diffraction analysis indicated that the products obtained have a high purity. The optical properties of the products are studied by IR and UV/Vis spectroscopy. UV/Vis spectra indicate that, compared with ferrocene bulk material, the nanospheres show an obvious blue shift. Cyclic voltammetry is used to test the electrocatalytic oxidation properties of the ferrocene nanospheres towards ascorbic acid on the glassy carbon electrode. The results show that the ferrocene‐nanosphere‐modified glassy carbon electrode exhibits a better electrocatalytic effect than that modified by the ferrocene bulk material in phosphate buffer (pH 5.00). The important factors in the preparation of and a possible mechanism for the formation of ferrocene nanospheres is also discussed. The method could potentially be applied to the preparation of nanomaterials of other organometallic compounds.
Laboratory fretting tests with thin wire specimens
Authors: Urchegui M.A. , Hartelt M. , Klaffke D. , Gómez X.
Published: March 2007

Wire ropes, due to their construction and application, are prone to fretting damages. In order to know the wear behaviour of individual wires under fretting conditions, laboratory tests are required. The present work describes the preliminary fretting tests accomplished with thin steel wires to optimise the testing procedure. The tests were carried out with ‘crossed‐cylinders’ configuration varying the stroke and normal load. Afterwards, the fretted surfaces were characterised by means of an optical and scanning electron microscope, and a diamond stylus. No significant influence of selected parameters was detected and a good correlation was proved for on‐line measured parameters and off‐line obtained values. Copyright © 2007 John Wiley & Sons, Ltd.
Fuzzy Clusterwise Generalized Structured Component Analysis
Authors: Hwang Heungsun , DeSarbo Wayne S. , Takane Yoshio
Published: March 2007

Generalized Structured Component Analysis (GSCA) was recently introduced by Hwang and Takane (2004) as a component-based approach to path analysis with latent variables. The parameters of GSCA are estimated by pooling data across respondents under the implicit assumption that they all come from a single, homogenous group. However, as has been empirically demonstrated by various researchers across a number of areas of inquiry, such aggregate analyses can often mask the true structure in data when respondent heterogeneity is present. In this paper, GSCA is generalized to a fuzzy clustering framework so as to account for potential group-level respondent heterogeneity. An alternating least-squares procedure is developed and technically described for parameter estimation. A small-scale Monte Carlo study involving synthetic data is carried out to compare the performance between the proposed method and an extant approach. In addition, an empirical application concerning alcohol use among adolescents from US northwestern urban areas is presented to illustrate the usefulness of the proposed method. Finally, a number of directions for future research are provided.
Kinetics of the plastoquinone pool oxidation following illumination
Authors: Ivanov Boris , Mubarakshina Maria , Khorobrykh Sergey
Published: March 2007

The oxidation of the PQ‐pool after illumination with 50 or 500 μmol quanta m−2
s−1 was measured in isolated thylakoids as the increase in ΔA
263, i.e., as the appearance of PQ. While it was not observed under anaerobic conditions, under aerobic conditions it was biphasic. The first faster phase constituted 26% or 44% of total reappearance of PQ, after weak or strong light respectively. The dependence on oxygen presence as well as the correlation with the rate of oxygen consumption led to conclusion that this phase represents the appearance of PQ from PQ
▪− produced in the course of PQH2 oxidation by superoxide accumulated in the light within the membrane.
Membrane protein assembly patterns reflect selection for non‐proliferative structures
Authors: Rath Arianna , Deber Charles M.
Published: March 2007

Membrane proteins that regulate solute movement are often built from multiple copies of an identical polypeptide chain. These complexes represent striking examples of self‐assembling systems that recruit monomers only until a prescribed level for function is reached. Here we report that three modes of assembly – distinguished by sequence and stoichiometry – describe all helical membrane protein complexes currently solved to high resolution. Using the 13 presently available non‐redundant homo‐oligomeric structures, we show that two of these types segregate with protein function: one produces energy‐dependent transporters, while the other builds channels for passive diffusion. Given such limited routes to functional complexes, membrane proteins that self‐assemble exist on the edge of aggregation, susceptible to mutations that may underlie human diseases.
Influence of Intimate Partner Violence During Pregnancy and Early Postpartum Depressive Symptoms on Breastfeeding Among Chinese Women in Hong Kong
Authors: Lau Ying , Chan Kin Sin
Published: March 2007

Numerous studies show that breastfeeding is beneficial to both mothers and babies. This study explores two understudied correlates that may influence breastfeeding initiation: intimate partner violence during pregnancy and early postnatal depressive symptoms. A cross‐sectional comparative study design investigated the correlates of feeding modes of 1200 Chinese mother and infant pairs in a university‐affiliated regional hospital in Hong Kong. The prevalence rates of breastfeeding and mixed feeding were 42.25% and 26.25%, respectively. Women who had no experience of intimate partner violence during pregnancy were significantly more likely to initiate breastfeeding (adjusted odds ratio = 1.84; 95% confidence interval, 1.16–2.91) after adjustment for demographic, socioeconomic, and obstetric variables. Early postnatal depressive symptoms were not significantly associated with feeding modes in a multinomial logistic regression model. Midwives are in a key position to identify and intervene to encourage more successful breastfeeding practice.
Reasons for Unprotected Intercourse in Adult Women: A Qualitative Study
Authors: Nettleman Mary , Brewer Jennifer , Ayoola Adejoke
Published: March 2007

Despite the focus on adolescents, most unintended pregnancies occur in adults. The objective of this study was to identify reasons why adult women have unprotected intercourse when they do not desire pregnancy. We held 4 focus groups to explore reasons for unprotected intercourse. Participants were adult women aged 18 to 39 who were unmarried, fertile, not currently pregnant, not desiring pregnancy, and who had recently had intercourse without using effective contraception. Sessions were audiotaped and transcripts were analyzed thematically. Women gave 146 reasons for unprotected intercourse. Four major categories emerged: method‐related, user‐related, partner‐related, and cost/access‐related reasons. The reasons for unprotected intercourse were numerous, but could be organized into a logical framework. The results suggest that multidimensional interventions may be needed to effectively reduce the rate of unintended pregnancy.
Finding Midwifery in Administrative Data Systems
Authors: Diers Donna
Published: March 2007

Nurse‐midwifery has accomplished remarkable clinical, policy, and political achievements using specially‐collected data. Today, midwifery practice data can be found in existing administrative data systems: birth registration, hospital data depositories, and claims files. Issues in finding midwifery as practice and profession in these data systems are discussed. Improving the integrity of data that reveal midwives as caregivers should be a priority.
Why Do Supportive Birth Attendants Become Directive of Maternal Bearing‐Down Efforts in Second‐Stage Labor?
Authors: Roberts Joyce M. , González Celina B. Pittman , Sampselle Carolyn
Published: March 2007

A supportive approach to care for women during the second stage of labor that primarily relies on the laboring woman's involuntary expulsive urges has been advocated. We aimed to learn about the clinical circumstances surrounding the caregiver shift from being primarily supportive to directing women regarding their bearing‐down efforts. This research analyzed the communications of 10 birth attendants and women during the expulsive phase of labor using videotapes recorded from two studies carried out between 1986 and the present. The occasions when a birth attendant shifted verbalizations were identified, and categories of the rationales that may have influenced the modification in caregiver behavior were developed. Birth attendants most frequently provided directions to help the woman push effectively, that is, to focus the woman's bearing‐down efforts during maternal distress, fatigue, fear, and pain to expedite the labor process (38% of the occasions of caregiver change in verbalizations). The next most frequent clinical situations when caregivers offered directions about “pushing” were diminished urge to bear‐down with epidural analgesia (10%), routine arbitrary practices (9% caregiver and 6% by supportive companion), and fetal distress (< 1%). A category of “supportive direction” (20%) was identified. This care strategy has not been previously reported. It combined direction with support in a way that was supportive rather than overriding the woman's involuntary efforts.
Randomized Controlled Trial of Very Early Mother‐Infant Skin‐to‐Skin Contact and Breastfeeding Status
Authors: Moore Elizabeth R. , Anderson Gene Cranston
Published: March 2007

This study was done to evaluate effects of maternal‐infant skin‐to‐skin contact during the first 2 hours postbirth compared to standard care (holding the infant swaddled in blankets) on breastfeeding outcomes through 1 month follow‐up. Healthy primiparous mother‐infant dyads were randomly assigned by computerized minimization to skin‐to‐skin contact (n = 10) or standard care (n = 10). The Infant Breastfeeding Assessment Tool was used to measure success of first breastfeeding and time to effective breastfeeding (time of the first of three consecutive scores of 10–12). Intervention dyads experienced a mean of 1.66 hours of skin‐to‐skin contact. These infants, compared to swaddled infants, had higher mean sucking competency during the first breastfeeding (8.7 ± 2.1 vs 6.3 ± 2.6; P < .02) and achieved effective breastfeeding sooner (935 ± 721 minutes vs 1737 ± 1001; P < .04). No significant differences were found in number of breastfeeding problems encountered during follow‐up (30.9 ± 5.51 vs 32.7 ± 5.84; P < .25) or in breastfeeding exclusivity (1.50 ± 1.1 vs 2.10 ± 2.2; P < .45). Sucking competency was also related to maternal nipple protractility (r = .48; P < .03). Very early skin‐to‐skin contact enhanced breastfeeding success during the early postpartum period. No significant differences were found at 1 month.
Is criticism under threat? Are critics compromised in an age of rapid production?
Authors: Calder Barnabas
Published: March 2007

This symposium, held at Building Design Partnership's offices on 21 September, was jointly organised by the International Committee of Architectural Critics (CICA), and its Chair, Dennis Sharp, and the Architecture Foundation, represented on the panel by its Director, Rowan Moore. The topic under investigation was the challenges posed to the critic by a period of massive architectural production: are critics being swamped by the quantity of new buildings, thus reducing the quality of criticism? In addition, is honest criticism held in check by the corporate power of architects, in a world where even ‘art house’ partnerships are now commonly ten times larger than their 1960s counterparts? In a panel of six distinguished critics, one might have expected to find at least six different opinions on any subject. The surprising thing about this symposium was the level of consensus that emerged.
The decorum of doors and windows, from the fifteenth to the eighteenth century
Authors: Kohane Peter , Hill Michael
Published: March 2007

Doors and windows were once among the primary means of articulating a facade. Tailored to the orders, they expressed the symmetry that guided the overall design of a building.
Furnishing the Fascist interior: Giuseppe Terragni, Mario Radice and the Casa del Fascio
Authors: Rifkind David
Published: March 2007

Building, furniture design and the decorative arts collaborate to embody Fascist political values and mass identity in an icon of modern architecture.
Validation-study conclusions from dietary reports by fourth-grade children observed eating school meals are generalisable to dietary reports by comparable children not observed
Authors: Smith Albert F , Baxter Suzanne Domel , Hardin James W , Guinn Caroline H , Royer Julie A , Litaker Mark S
Published: March 2007

Objective

To investigate the effect of observing school meals on children's dietary reports.

Subjects and setting

One hundred and twenty children randomly selected, but with half girls, from usual school-meal eaters among 312 volunteers (from all 443 fourth-grade children in six schools in one district).

Design

Children were assigned randomly to one of 12 conditions yielded by crossing observation status (observed; not observed), target period (previous day; prior 24 hours), and interview time (morning; afternoon; evening).

Results

Response variables included interview length, number of meals and snacks reported for the target period, and, for two school meals, number of meal components reported, importance-weighted number of items reported and kilocalories reported. These variables were transformed to principal components; two were retained (1, the school meal variables; 2, interview length and number of meals and snacks). Analyses of variance on principal component scores tested effects of observation status, target period, interview time and all interactions. Observation status did not affect scores on either retained principal component. Scores on Component 2 showed that more intake was reported in prior-24-hours interviews than in previous-day interviews.

Conclusions

The effect of target period on reported intake indicates that the response variables were sufficiently reliable to detect manipulations. This, together with the finding that response variables did not depend on observation status, suggests that observation of school meals does not affect fourth-grade children's dietary reports, and that conclusions about dietary reports by fourth-grade children observed eating school meals in validation studies may be generalised to dietary reports by comparable children not observed.
Glycaemic index, glycaemic load and ovarian cancer risk: a prospective cohort study
Authors: Silvera Stephanie AN , Jain Meera , Howe Geoffrey R , Miller Anthony B , Rohan Thomas E
Published: March 2007

Background

There is some evidence that plasma insulin levels might influence ovarian cancer risk. Glyacemic index (GI) and glycaemic load (GL) are measures that allow the carbohydrate content of individual foods to be classified according to their postprandial glycaemic effects and hence their effects on circulating insulin levels. Therefore, we examined ovarian cancer risk in association with GI and GL, and intake of dietary carbohydrate and sugar.

Methods

The study was conducted in a prospective cohort of 49 613 Canadian women enrolled in the National Breast Screening Study (NBSS) who completed a self-administered food-frequency questionnaire (FFQ) between 1980 and 1985. Linkages to national mortality and cancer databases yielded data on deaths and cancer incidence, with follow-up ending between 1998 and 2000. Data from the FFQ were used to estimate overall GI and GL, and Cox proportional hazards models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for the association between energy-adjusted quartile levels of GL, overall GI, total carbohydrates, total sugar and ovarian cancer risk.

Results

During a mean 16.4 years of follow-up, we observed 264 incident ovarian cancer cases. GI and total carbohydrate and sugar intakes were not associated with ovarian cancer risk in the total cohort. GL was positively associated with a 72% increase in risk of ovarian cancer (HR = 1.72, 95% CI = 1.13–2.62,Ptrend = 0.01) and the magnitude of the association was slightly greater among postmenopausal (HR = 1.89, 95% CI = 0.98–3.65,Ptrend = 0.03) than among premenopausal women (HR = 1.64, 95% CI = 0.95–2.88,Ptrend = 0.07).

Conclusions

Our data suggest that consumption of diets with high GL values may be associated with increased risk of ovarian cancer.
The role of parents' educational background in healthy lifestyle practices and attitudes of their 6-year-old children
Authors: Stenhammar Christina , Sarkadi Anna , Edlund Birgitta
Published: March 2007

Objective

The aim of the present study was to examine parents' reported and desired frequencies (practices vs. attitudes) of their 6-year-old children's meals, nutritional intake and lifestyle components, as well as possible obstacles and desired support with respect to higher or lower educational backgrounds.

Design

Cross-sectional questionnaire study.

Setting

Five elementary schools in Uppsala, Sweden.

Subjects

Parents of 176 6-year-old pupils attending the first grade. The total response rate was 89.7%.

Results

Parents with a college degree reported that their 6-year-olds had a higher frequency of milk, fruit and vegetable intake, more physical activity and fewer hours watching television compared with parents with a secondary school degree. Congruent to these differences in reported practices, more parents with a college degree desired a higher frequency of milk, fruit and vegetable intake, more physical exercise and less television viewing for their children. Regarding parents' desired meal frequencies during the week, no differences between the groups with higher and lower levels of education were found. Despite similar attitudes, however, parents with a college degree reported that their children ate mostly all meals significantly more often during the week. Both parent groups stated lack of time as the most common obstacle in providing their children with desired lifestyle practices, although parents with a secondary school education added lack of money as a contributing factor.

Conclusions

As attitudes are not always reflected in reported practices, it seems a fruitful approach to assess both, as well as obstacles perceived by parents, before planning interventions to enhance healthy lifestyle habits in children.
Cross‐shore sediment transport on natural beaches and its relation to sandbar migration patterns: 1. Field observations and derivation of a transport parameterization
Authors: Mariño‐Tapia I. J. , Russell P. E. , O'Hare T. J. , Davidson M. A. , Huntley D. A.
Published: March 2007

Cross‐shore sediment transport processes are investigated with measurements of horizontal velocity and sediment suspension obtained with electromagnetic current meters and optical backscatter sensors on five different beaches across Europe. Data were gathered under a wide variety of hydrodynamic and morphological conditions spanning the swash, surf, and shoaling zones. Results show that the near bed velocity moments, normalized by the local energy level (〈ut2〉n), have consistent shapes (shape functions) when plotted against normalized cross‐shore depth (h/hb). According to the energetics approach, near bed velocity moments are good descriptors of sediment transport processes, consequently, the shape functions describe and quantify the cross‐shore distribution of the most relevant cross‐shore sediment transport processes. The pattern consists of net onshore transport in the swash zone, offshore transport in the surf zone, and onshore transport in the shoaling zone thereby producing divergence of sediment in the inner surf/swash zone and convergence in the breaker zone. In consequence, the shape function supports the breakpoint hypothesis for sandbar generation. This behavior is a product of the balance between multiple opposing mechanisms including undertow, coupling between mean flows and short (long) wave stirring, short (long) wave skewness, and long wave coupling with short wave variance. The cross‐shore structure of the measured and normalized cross‐shore sediment fluxes is consistent with the velocity moment shape functions, showing the robustness of the approach. Apart from the shortcomings bound to the energetics approach, the present parameterization is also limited due to the difficulty of defining with confidence a breaker depth (hb) in bar‐trough systems.
New approach for determining the normal of the bow shock based on Cluster four‐point magnetic field measurements
Authors: Shen C. , Dunlop M. , Li X. , Liu Z. X. , Balogh A. , Zhang T. L. , Carr C. M. , Shi Q. Q. , Chen Z. Q.
Published: March 2007

We introduce a new approach to determine the normal of Earth’s bow shock, based on four‐point magnetic field measurements. The method obtains the local bow shock normal, based on the assumption that the normal is in the opposite direction to the gradient of the magnetic pressure or magnetic strength (within the shock front). This gradient can be deduced from the four‐point magnetic field measurements of Cluster. Applying the method, we calculate the normal of the bow shock for 28 Cluster crossing events from March to April of 2002 and February to March of 2004 and compare the results for the boundary orientation to commonly known methods, i.e., minimum variance analysis and the coplanarity theorem. In addition, we compare results of the normal obtained by four spacecraft timing analysis, under the assumptions of local planarity and constant velocity of the boundary (triangulation). It is known that minimum variance analysis often fails because of the temporal variation of the bow shock and coplanarity analysis often fails because of the existence of an overshoot or poor determination of the downstream magnetic field due to plasma disturbance. We find that the gradient analysis agrees most closely with the timing analysis, and, in general, the shock orientations obtained fit the expected bow shock geometry. The gradient method is valid for quasi‐stable shocks and does not require the conditions of coplanarity or constant velocity of the bow shock to be satisfied. Its accuracy depends on this stability and the relative spatial scale of the shock, which should be large compared to the spacecraft configuration. A feature of the method, however, is that it provides an estimate of the normal point by point in time, allowing the nature of the spacecraft sampling to be monitored in terms of behavior as each shock event is traversed.
Micromagnetic coercivity distributions and interactions in chondrules with implications for paleointensities of the early solar system
Authors: Acton Gary , Yin Qing‐Zhu , Verosub Kenneth L. , Jovane Luigi , Roth Alex , Jacobsen Benjamin , Ebel Denton S.
Published: March 2007

Chondrules in chondritic meteorites record the earliest stages of formation of the solar system, potentially providing information about the magnitude of early magnetic fields and early physical and chemical conditions. Using first‐order reversal curves (FORCs), we map the coercivity distributions and interactions of 32 chondrules from the Allende, Karoonda, and Bjurbole meteorites. Distinctly different distributions and interactions exist for the three meteorites. The coercivity distributions are lognormal shaped, with Bjurbole distributions being bimodal or trimodal. The highest‐coercivity mode in the Bjurbole chondrules is derived from tetrataenite, which interacts strongly with the lower‐coercivity grains in a manner unlike that seen in terrestrial rocks. Such strong interactions have the potential to bias paleointensity estimates. Moreover, because a significant portion of the coercivity distributions for most of the chondrules is <10 mT, low‐coercivity magnetic overprints are common. Therefore paleointensities based on the REM method, which rely on ratios of the natural remanent magnetization (NRM) to the saturation isothermal remanent magnetization (IRM) without magnetic cleaning, will probably be biased. The paleointensity bias is found to be about an order of magnitude for most chondrules with low‐coercivity overprints. Paleointensity estimates based on a method we call REMc, which uses NRM/IRM ratios after magnetic cleaning, avoid this overprinting bias. Allende chondrules, which are the most pristine and possibly record the paleofield of the early solar system, have a mean REMc paleointensity of 10.4 μT. Karoonda and Bjurbole chondrules, which have experienced some thermal alteration, have REMc paleointensities of 4.6 and 3.2 μT, respectively.
Aerosol optical depth (AOD) and Ångström exponent of aerosols observed by the Chinese Sun Hazemeter Network from August 2004 to September 2005
Authors: Xin Jinyuan , Wang Yuesi , Li Zhanqing , Wang Pucai , Hao Wei Min , Nordgren Bryce L. , Wang Shigong , Liu Guangren , Wang Lili , Wen Tianxue , Sun Yang , Hu Bo
Published: March 2007

To reduce uncertainties in the quantitative assessment of aerosol effects on regional climate and environmental changes, extensive measurements of aerosol optical properties were made with handheld Sun photometers in the Chinese Sun Hazemeter Network (CSHNET) starting in August 2004. Regional characteristics of the aerosol optical depth (AOD) at 500 nm and Ångström exponent (α) computed using 405, 500, and 650 nm were analyzed for the period of August 2004 to September 2005. The smallest mean AOD (∼0.15) was found in the Tibetan Plateau where α showed the largest range in value (0.06–0.9). The remote northeast corner of China was the next cleanest region with AODs ranging from 0.19 to 0.21 and with the largest α (1.16–1.79), indicating the presence of fine aerosol particles. The forested sites exhibited moderate values of AOD (0.19–0.51) and α (0.97–1.47). A surprising finding was that the AOD measured at a few desert sites in northern China were relatively low, ranging from 0.24 to 0.36, and that α ranged from 0.42 to 0.99, presumably because of several dust‐blowing episodes during the observation period. The AOD observed over agricultural areas ranges from 0.38 to 0.90; α ranges from 0.55 to 1.11. These values do not differ much from those observed at the inland urban and suburban sites where AOD ranges from 0.50 to 0.69 and α ranges from 0.90 to 1.48. Given the geographic heterogeneity and the rapid increase in urbanization in China, much longer and more extensive observations are required.
Super Picard-Fuchs equation and monodromies for supermanifolds
Authors: Kaura Payal , Misra Aalok , Shukla Pramod
Published: March 2007

Following, Aganagic and Vafa (e-print hep-th/0403192) and Hori and Vafa (e-print hep-th/0002222), we discuss the Picard-Fuchs equation for the super Landau-Ginsburg mirror to the super Calabi-Yau in WCP(3∣2)[1,1,1,3∣1,5] (using techniques of Greene and Lazaroiu [Nucl. Phys. B 604, 181 (2001), e-print hep-th/0001025] and Misra [Fortschr. Phys. 52, 831 (2004), e-print hep-th/0311186]), Meijer basis of solutions, and monodromies (at 0,1 and ∞) in the large and small complex structure limits, as well as obtain the mirror hypersurface, which in the large Kähler limit turns out to be either a bidegree-(6,6) hypersurface in WCP(3∣1)[1,1,1,2]×WCP(1∣1)[1,1∣6] or a (Z2 singular) bidegree-(6,12) hypersurface in WCP(3∣1)[1,1,2,6∣6]×WCP(1∣1)[1,1∣6].
Thermal recovery from stress-induced high-κ dielectric film degradation
Authors: O’Sullivan B. J. , Pantisano L. , Roussel P. , Degraeve R. , Groeseneken G. , DeGendt S. , Heyns M. M.
Published: March 2007

This work presents a detailed analysis of the ability of high-κ materials to recover from Fowler-Nordheim stress-induced degradation. Forming gas and high temperature rapid thermal anneal steps are compared to determine their efficiency at trap recovery. The annealing responses of the technologically relevant HfSiON and HfO2 materials (equivalent oxide thickness <2nm) are correlated with structural differences in these dielectrics, trap generation rate, charge centroids, and defect de-passivation. It is shown that stress-induced damage can be fully recovered for HfO2 by high temperature annealing.
The effective local potential method: Implementation for molecules and relation to approximate optimized effective potential techniques
Authors: Izmaylov Artur F. , Staroverov Viktor N. , Scuseria Gustavo E. , Davidson Ernest R. , Stoltz Gabriel , Cancès Eric
Published: March 2007

We have recently formulated a new approach, named the effective local potential (ELP) method, for calculating local exchange-correlation potentials for orbital-dependent functionals based on minimizing the variance of the difference between a given nonlocal potential and its desired local counterpart [V. N. Staroverov et al., J. Chem. Phys. 125, 081104 (2006)]. Here we show that under a mildly simplifying assumption of frozen molecular orbitals, the equation defining the ELP has a unique analytic solution which is identical with the expression arising in the localized Hartree-Fock (LHF) and common energy denominator approximations (CEDA) to the optimized effective potential. The ELP procedure differs from the CEDA and LHF in that it yields the target potential as an expansion in auxiliary basis functions. We report extensive calculations of atomic and molecular properties using the frozen-orbital ELP method and its iterative generalization to prove that ELP results agree with the corresponding LHF and CEDA values, as they should. Finally, we make the case for extending the iterative frozen-orbital ELP method to full orbital relaxation.
Phase separation and nanoparticle formation in Cr-dosed FePt thin films
Authors: Won C. , Keavney D. J. , Bader S. D.
Published: March 2007

Cr-dosed FePt films with total thicknesses of 1.8 and 3.6nm were grown in an ultrahigh vacuum at room temperature and studied by means of the surface magneto-optic Kerr effect, scanning electron microscopy, and x-ray magnetic circular dichroism. After annealing at 550°C, the L10 and A1 phases are spatially separated. In the L10 phase, round nanoparticles form that are 15±4.8nm in diameter and possess out-of-plane magnetic easy axes. An addition of <0.01nm Cr enhances the coercivity (∼0.9T), which then decreases with additional Cr, and a spin reorientation transition occurs near 0.3nm Cr dosage as the L10 islands disappear. Segregation of Cr during annealing is believed to be responsible for the formation of round FePt islands and the separation of the L10 islands and planar A1 phase.
Dissociative wave packets and dynamic resonances
Authors: Cardoza David , Pearson Brett J. , Weinacht Thomas
Published: March 2007

The authors examine the role of dynamic resonances in laser driven molecular fragmentation. The yields of molecular fragments can undergo dramatic changes as an impulsively excited dissociative wave packet passes through a dynamic resonance. The authors compare three different kinds of dynamic resonances in a series of molecular families and highlight the possibility of characterizing the dissociative wave function as it crosses the resonance location.
State dynamics of acetylene excited to individual rotational level of the V12K1,1,2 subbands
Authors: Makarov Vladimir I. , Kochubei Sergei A. , Khmelinskii Igor V.
Published: March 2007

The dynamics of the IR emission induced by excitation of the acetylene molecule at the 32Ka2, ÃAu1←41la1,X̃Σg+1 transition was investigated. Vibrationally resolved IR emission spectra were recorded at different delay times after the laser excitation pulse. The observed IR emission was assigned to transitions between vibrational levels of the acetylene molecule in the ground state. Values of the relaxation parameters of different vibrational levels of the ground state were obtained. The Ti→Tj transition was detected by cavity ring-down spectroscopy in the 455nm spectral range after excitation of the acetylene molecule at the 32Ka2same transition. Rotationally resolved spectra of the respective transition were obtained and analyzed at different delay times after the laser excitation pulse. The dynamics of the S1→Tx→T1→S0 transitions was investigated, and the relaxation parameter values were estimated for the T1 state.
Dynamics of resistive double tearing modes with broad linear spectra
Authors: Bierwage Andreas , Benkadda Sadruddin , Hamaguchi Satoshi , Wakatani Masahiro
Published: March 2007

The nonlinear evolution of resistive double tearing modes (DTMs) with safety factor values q=1 and q=3 is studied with a reduced cylindrical model of a tokamak plasma. We focus on cases where the resonant surfaces are a small distance apart. Recent numerical studies have shown that in such configurations high-m modes are strongly unstable and may peak around m=mpeak∼10. In this paper, it is first demonstrated that this result agrees with existing linear theory for DTMs. Based on this theory, a semiempirical formula for the dependence of mpeak on the system parameters is proposed. Second, with the use of nonlinear simulations, it is shown that the presence of fast growing high-m modes leads to a rapid turbulent collapse in an annular region, where small magnetic island structures form. Furthermore, consideration is given to the evolution of low-m modes, in particular the global m=1 internal kink, which can undergo nonlinear driving through coupling to fast growing linear high-m DTMs. Factors influencing the details of the dynamics are discussed. These results may be relevant to the understanding of the magnetohydrodynamic activity near the minimum of q and may thus be of interest for studies on stability and confinement of advanced tokamaks.
Least uncertainty principle in deformation quantization
Authors: Gerstenhaber Murray
Published: March 2007

Deformation quantization generally produces families of cohomologically equivalent quantizations of a single physical system. We conjecture that the physically meaningful ones (i) allow enough observable energy distributions, i.e., ones for which no pure quantum state has negative probability, and (ii) reduce the uncertainty in the probability distribution of the resulting quantum states. For the simple harmonic oscillator this principle selects the classic Groenewold-Moyal (or Weyl) product on phase space while for the free particle, in which there is no real quantization, all cohomologically equivalent quantizations are equally good.
Giant pop-ins and amorphization in germanium during indentation
Authors: Oliver David J. , Bradby Jodie E. , Williams Jim S. , Swain Michael V. , Munroe Paul
Published: March 2007

Sudden excursions of unusually large magnitude (>1 μm), “giant pop-ins,” have been observed in the force-displacement curve for high load indentation of crystalline germanium (Ge). A range of techniques including Raman microspectroscopy, focused ion-beam cross sectioning, and transmission electron microscopy, are applied to study this phenomenon. Amorphous material is observed in residual indents following the giant pop-in. The giant pop-in is shown to be a material removal event, triggered by the development of shallow lateral cracks adjacent to the indent. Enhanced depth recovery, or “elbowing,” observed in the force-displacement curve following the giant pop-in is explained in terms of a compliant response of plates of material around the indent detached by lateral cracking. The possible causes of amorphization are discussed, and the implications in light of earlier indentation studies of Ge are considered.
Low frequency noise characterizations of ZnO nanowire field effect transistors
Authors: Wang Wenyong , Xiong Hao D. , Edelstein Monica D. , Gundlach David , Suehle John S. , Richter Curt A. , Hong Woong-Ki , Lee Takhee
Published: March 2007

We fabricated ZnO nanowire field effect transistors (FETs) and systematically characterized their low frequency (f) noise properties. The obtained noise power spectra showed a classical 1∕f dependence. A Hooge’s constant of 5×10−3 was estimated from the gate dependence of the noise amplitude. This value is within the range reported for complementary metal-oxide semiconductor (CMOS) FETs with high-k dielectrics, supporting the concept that nanowires can be utilized for future beyond-CMOS electronic applications from the point of view of device noise properties. ZnO FETs measured in a dry O2 environment displayed elevated noise levels that can be attributed to increased fluctuations associated with O2− on the nanowire surfaces.
Thin active region, type II superlattice photodiode arrays: Single-pixel and focal plane array characterization
Authors: Little J. W. , Svensson S. P. , Beck W. A. , Goldberg A. C. , Kennerly S. W. , Hongsmatip T. , Winn M. , Uppal P.
Published: March 2007

We have measured the radiometric properties of two midwave infrared photodiode arrays (320×256pixel2 format) fabricated from the same wafer comprising a thin (0.24μm), not intentionally doped InAs∕GaSb superlattice between a p-doped GaSb layer and a n-doped InAs layer. One of the arrays was indium bump bonded to a silicon fanout chip to allow for the measurement of properties of individual pixels, and one was bonded to a readout integrated circuit to enable array-scale measurements and infrared imaging. The superlattice layer is thin enough that it is fully depleted at zero bias, and the collection efficiency of photogenerated carriers in the intrinsic region is close to unity. This simplifies the interpretation of photocurrent data as compared with previous measurements made on thick superlattices with complex doping profiles. Superlattice absorption coefficient curves, obtained from measurements of the external quantum efficiency using two different assumptions for optical coupling into the chip, bracket values calculated using an eight-band k∙p model. Measurements of the quantum efficiency map of the focal plane array were in good agreement with the single-pixel measurements. Imagery obtained with this focal plane array demonstrates the high uniformity and crystal quality of the type II superlattice material.
Simulation of DNA motion in a microchannel using stochastic rotation dynamics
Authors: Watari Nobuhiko , Makino Masato , Kikuchi Norio , Larson Ronald G. , Doi Masao
Published: March 2007

The authors propose a method to simulate the DNA motion in microchannels of complex geometry. It is based on stochastic rotation dynamics using a new scheme for the boundary condition. The method enables them to define a boundary wall of arbitrary shape and to describe a wall moving at an arbitrary velocity. As an application, they simulate the motion of DNA in Poiseuille flow between two parallel planes and show that DNA molecules tend to concentrate near the center of the channel in agreement with experimental results.
Perturbation analysis on gas flow in a straight microchannel
Authors: Qin Feng-Hua , Sun De-Jun , Yin Xie-Yuan
Published: March 2007

In the present paper, a steady subsonic gas flow either in a circular micropipe or in a planar microchannel driven by pressure within the slip flow regime is studied theoretically by using a perturbation expansion method to solve compressible Navier-Stokes equations. The isothermal flow assumption used in previous theoretical studies is given up. High-order boundary conditions of velocity slip and temperature jump are adopted at the wall. The set of dimensionless governing equations with two small similarity parameters, namely, the ratio of height to length ε, and the Knudsen number Kn, is approximated successively by using the perturbation expansions. The various cases such as ε≪Kn2, ε∼Kn2, and ε∼Kn1.5 are studied in detail. Explicit analytical solutions for pressure, density, velocity, temperature, and mass flow rate are obtained up to order of O(Kn2). It is shown that the solution formulas for long channels (ε≪Kn2) in lower order are in exact agreement with previous theoretical results. In particular, it is proved that the isothermal flow assumption is indeed reliable for relatively lower-order expansions. However, for higher-order expansions, the flow cannot be considered as isothermal, and the higher-order temperature correction is also given. The present high-order perturbation solutions can be applied even to a relatively shorter channel, and the results agree very well with those by the direct simulation Monte Carlo approach.
Temperature-dependent current injection and lasing in T-shaped quantum-wire laser diodes with perpendicular p- and n-doping layers
Authors: Okano Makoto , Liu Shu-man , Ihara Toshiyuki , Itoh Hirotake , Yoshita Masahiro , Akiyama Hidefumi , Pfeiffer Loren N. , West Kenneth , Malis Oana
Published: March 2007

The authors measured the temperature dependence of the lasing properties of current-injection T-shaped GaAs∕AlGaAs quantum-wire (T-wire) lasers with perpendicular p- and n-doping layers. The T-wire lasers with high-reflectivity coatings on both cleaved facets achieved continuous-wave single-mode operation between 5 and 110K. The lowest threshold current was 2.1mA at 100K. The temperature dependences of differential quantum efficiency and threshold current were attributed mainly to that of current-injection efficiency.
Induced emission cross section of a possible laser line in Nd:Y2O3 ceramics at 1.095μm
Authors: Fukabori Akihiro , Sekita Masami , Ikegami Takayasu , Iyi Nobuo , Komatsu Toshiki , Kawamura Masayuki , Suzuki Makoto
Published: March 2007

In this study, we measured the change of the optical transmittance for calcination temperatures, in steps of 10°, at two different sintering temperatures. It was found that the optical transmittance is highly dependent on the calcination temperature. The highest optical transmittance obtained was 70% for the transparent Y2O3 (yttria) ceramics produced without the use of additives and high injection presure in this study, higher than the highest reported value of 65%. Optical absorption and emission spectra of Nd:Y2O3 obtained from a low temperature synthesis process were measured. The energy level structure of Nd3+ in the Y2O3 ceramics was determined for a 1mol% Nd concentration. The induced emission cross section was calculated to be in the range of 3.2×10−19–1.1×10−17cm2 for the 1mol% Nd-doped Y2O3 ceramics. Furthermore, a laser line possibly has been identified in this study, in the Nd:Y2O3 ceramic at 1.095μm.