bluuebunny/crossref_metadata_2025 huggingface dataset:
MEN’S APPROVAL OF FAMILY PLANNING IN BANGLADESH
Authors: ISLAM MOHAMMAD AMIRUL , PADMADAS SABU S. , SMITH PETER W.F.
Published: February 2006

This article attempts to evaluate men’s approval of family planning in Bangladesh using the couple data set from the recent Bangladesh Demographic and Health Survey (BDHS), 1999–2000. Family planning approval is addressed both from individual and couple perspectives. Analysis of BDHS data shows that about 85% of the wives report that their husbands approve of family planning, which is lower than the wives’ own approval rate (95%). Using the couple data set, husbands’ characteristics were matched to the wives’ responses on family planning approval. Regression analyses show that age, education, access to TV, inter-spousal communication, current use of family planning and the number of living children significantly determine family planning approval among both men as well as couples. Family planning approval was found to be much lower in Sylhet than in the other administrative divisions. Multilevel modelling analysis suggests almost negligible variation at the community level. The findings indicate the need for careful evaluation of the DHS questions in order to measure appropriately men’s family planning attitudes.
TREATMENT-SEEKING PRACTICES FOR MALARIA IN PREGNANCY AMONG RURAL WOMEN IN MUKONO DISTRICT, UGANDA
Authors: MBONYE ANTHONY K. , NEEMA STELLA , MAGNUSSEN PASCAL
Published: February 2006

Understanding treatment-seeking practices for malaria in pregnancy is necessary in designing effective programmes to address the high malaria morbidity in pregnancy. This study assessed women’s perceptions on malaria in pregnancy, recognition of early signs of pregnancy and of malaria, and the cultural context in which treatment seeking takes place in Mukono District. Focus group discussions (FGD) and key informant interviews were conducted among pregnant women, non-pregnant women, adolescents and men. The results showed that malaria, locally known as omusujja, was perceived as the most common cause of ill health among pregnant women. Although malaria commonly presents with fever, some pregnant women feel hot in the womb with or without signs of fever and this illness, locally known as nabuguma, may lead to progressive weakness and occasionally to miscarriage and few respondents associated it with malaria. Primigravidae, adolescents and men were not considered at risk of omusujja or nabuguma. Similarly anaemia and low birth weight were not associated with malaria; in fact paleness was described as a normal sign of pregnancy. There are cultural and social pressures on married women to get pregnant and this forces them to conceal symptoms like feeling feverishness, backache, nausea, general weakness, loss of appetite and vomiting until they are sure these are due to pregnancy. Most women, however, could not differentiate symptoms of malaria from those of early pregnancy. There is a belief that omusujja is a normal sign of pregnancy and this is coupled with a strong cultural practice of using herbs and clays as a first resort to treat pregnancy ailments including malaria. The cultural beliefs and practices regarding delivery of twin and first births, coupled with the high cost of care, prevent women from delivering and using other services at health units.
ROLE OF FAMILY TYPE IN THE IDEALIZATION OF A LARGER NUMBER OF CHILDREN BY HUSBANDS IN PAKISTAN
Authors: IQBAL AVAN BILAL , AKHUND SAIMA
Published: February 2006

This study focuses on determining the number of children considered ideal by Pakistani husbands and identifying the factors associated with this, with a special emphasis on family type. A cross-sectional survey was conducted among married males residing in four areas of Khairpur district. An equal number of study participants were selected systematically from each field site to achieve the required sample size of 500. Interviews were conducted by trained fieldworkers using a structured questionnaire to obtain information on background socioeconomic characteristics, family structure and reproductive health knowledge and practices, in particular family planning. Multivariate logistic regression analyses were used to assess the hypothesis that family type has an independent association with husbands’ idealization of a larger number of children. The mean ideal number of children perceived by husbands was four. Living in an extended family (AOR=1·81; 95%CI: 1·11, 3·35) and being illiterate (AOR=2·13, 95%CI; 1·33, 3·42) are significantly associated with idealization of a larger number of children by the husband, while adjusting for socioeconomic status, family structure and family planning information. Understanding the dynamics of family type and its effects on husbands’ opinions regarding ideal number of children can help strengthen population control efforts in Pakistan.
THE INFLUENCE OF METHOD-RELATED PARTNER VIOLENCE ON COVERT PILL USE AND PILL DISCONTINUATION AMONG WOMEN LIVING IN LA PAZ, EL ALTO AND SANTA CRUZ, BOLIVIA
Authors: McCARRAHER DONNA R. , MARTIN SANDRA L. , BAILEY PATRICIA E.
Published: February 2006

Intimate partner violence is widespread worldwide. While assumed to impact women’s ability to use contraceptive methods, few data are available to support this claim. In this study, eight focus group discussions were conducted to guide questionnaire development and to provide contextual information. Participants were women who were currently using the pill and women who had used the pill previously. In addition, 300 women were interviewed who initiated oral contraceptive pill use between December 1995 and April 1996. Participants were interviewed 3–6 months later to investigate the role intimate partner violence played in covert pill use and pill discontinuation. Special study procedures for asking women questions about violence were employed. Nineteen per cent of the women interviewed were using the pill covertly. The odds of covert pill use were four times higher in El Alto and La Paz than in Santa Cruz. Women who used the pill covertly were more likely to have experienced method-related partner violence (OR=21.27) than women whose partners knew of their pill use. One-third of the women had discontinued pill use at the time of the interview. In the final multivariate analysis, having experienced side-effects (OR=2.37) was a significant predictor of pill discontinuation and method-related partner violence was marginally predictive (OR=1.91; 95% CI 1.0–3.66). While efforts are ongoing to incorporate men into family planning programmes, some male partners oppose, and in some situations violently oppose, contraceptive use. The needs of women with these types of partners must not be overlooked.
An XYZ Micromanipulator with three translational degrees of freedom
Authors: Jensen Kimberly A. , Lusk Craig P. , Howell Larry L.
Published: February 2006

This paper introduces a three degree of freedom XYZ Micromanipulator (XYZM) that is fabricated in the $x$-$y$ plane and positions components in the $x$, $y$, and $z$ directions using three independent linear inputs. The mechanism positions components on a platform using three legs, each composed of a slider mechanism and a parallelogram mechanism.

Three versions of the XYZM were fabricated and tested using surface micromachining processes: the rigid-body, offset, and compliant XYZM. Slider displacements of 45 micrometers result in a predicted out-of-plane displacement of 188 micrometers for the rigid-body XYZM, 205 micrometers for the offset XYZM, and 262 micrometers for the compliant XYZM.
Quantum robot: structure, algorithms and applications
Authors: Dong Daoyi , Chen Chunlin , Zhang Chenbin , Chen Zonghai
Published: February 2006

A brand-new paradigm of robots–quantum robots–is proposed through the fusion of quantum theory with robot technology. A quantum robot is essentially a complex quantum system which generally consists of three fundamental components: multi-quantum computing units (MQCU), quantum controller/actuator, and information acquisition units. Corresponding to the system structure, several learning control algorithms, including quantum searching algorithms and quantum reinforcement learning algorithms, are presented for quantum robots. The theoretical results show that quantum robots using quantum searching algorithms can reduce the complexity of the search problem from O($N^2)$ in classical robots to O($N\sqrt N)$. Simulation results demonstrate that quantum robots are also superior to classical robots in efficient learning under novel quantum reinforcement learning algorithms. Considering the advantages of quantum robots, some important potential applications are also analyzed and prospected.
A comparison between direct and indirect dynamic parameter identification methods in industrial robots
Authors: Benimeli Francesc , Mata Vicente , Valero Francisco
Published: February 2006

The estimation of dynamic parameters in mechanical systems constitutes an issue of crucial importance both for inverse dynamics based control strategies and dynamic simulation applications where high accuracy is required. The identification procedures can be classified in two main groups: indirect and direct procedures. The first ones act sequentially in several steps in each of them parameters of different nature (basically friction and inertial parameters) are identified by means of specifically designed experiments, while the direct procedures allow the identification of all parameters defining de dynamic model in a single stage. In this paper, the implementation and comparison of an indirect and a direct identification procedures on an industrial robot provided with an open control architecture is addressed.
Liberal Rights in a Pareto-optimal Code
Authors: RILEY JONATHAN
Published: February 2006

A Millian response is presented to Sen's celebrated Paretian liberal impossibility theorem. It is argued that Millian Paretian liberalism is possible, if the application of Paretian norms is restricted to the selection of an optimal code of liberal justice and rights, as well as to individual choices made in compliance with the rules of the code. Key steps in outlining the Millian response include suitably modifying Sen's social choice formulation of the idea of claim-right to personal liberty, and incorporating within social choice theory the distinction between a right and its direction of exercise. The Millian response is illustrated in the context of Sen's original example of the ‘prude’ and the ‘lewd’. If the argument is successful, coherent and appealing liberal versions of Pareto-inclusive philosophies such as utilitarianism, contractualism and neo-republicanism are feasible in principle.
Application of aerosol hygroscopicity measured at the Atmospheric Radiation Measurement Program's Southern Great Plains site to examine composition and evolution
Authors: Gasparini Roberto , Li Runjun , Collins Don R. , Ferrare Richard A. , Brackett Vincent G.
Published: February 2006

A Differential Mobility Analyzer/Tandem Differential Mobility Analyzer (DMA/TDMA) was used to measure submicron aerosol size distributions, hygroscopicity, and occasionally volatility during the May 2003 Aerosol Intensive Operational Period (IOP) at the Central Facility of the Atmospheric Radiation Measurement Program's Southern Great Plains (ARM SGP) site. Hygroscopic growth factor distributions for particles at eight dry diameters ranging from 0.012 μm to 0.600 μm were measured throughout the study. For a subset of particle sizes, more detailed measurements were occasionally made in which the relative humidity or temperature to which the aerosol was exposed was varied over a wide range. These measurements, in conjunction with backtrajectory clustering, were used to infer aerosol composition and to gain insight into the processes responsible for evolution. The hygroscopic growth of both the smallest and largest particles analyzed was typically less than that of particles with dry diameters of about 0.100 μm. It is speculated that condensation of secondary organic aerosol on nucleation mode particles is largely responsible for the minimal hygroscopic growth observed at the smallest sizes considered. Growth factor distributions of the largest particles characterized typically contained a nonhygroscopic mode believed to be composed primarily of dust. A model was developed to characterize the hygroscopic properties of particles within a size distribution mode through analysis of the fixed size hygroscopic growth measurements. The performance of this model was quantified through comparison of the measured fixed size hygroscopic growth factor distributions with those simulated through convolution of the size‐resolved concentration contributed by each of the size modes and the mode‐resolved hygroscopicity. This transformation from size‐resolved hygroscopicity to mode‐resolved hygroscopicity facilitated examination of changes in the hygroscopic properties of particles within a size distribution mode that accompanied changes in the sizes of those particles. This model was used to examine three specific cases in which the sampled aerosol evolved slowly over a period of hours or days.
Eulerian derivation of the Coriolis force
Authors: Kageyama Akira , Hyodo Mamoru
Published: February 2006

In textbooks of geophysical fluid dynamics, the Coriolis force and the centrifugal force in a rotating fluid system are derived by making use of the fluid parcel concept. In contrast to this intuitive derivation to the apparent forces, more rigorous derivation would be useful not only for the pedagogical purpose but also for the applications to other kinds of rotating geophysical systems rather than the fluid. The purpose of this paper is to show a general procedure to derive the transformed equations in the rotating frame of reference based on the local Galilean transformation and rotational coordinate transformation of field quantities. The generality and usefulness of this Eulerian approach is demonstrated in the derivation of apparent forces in rotating fluids as well as the transformed electromagnetic field equation in the rotating system.
Simulation of high‐spectral‐resolution infrared signature of overlapping cirrus clouds and mineral dust
Authors: Hong Gang , Yang Ping , Huang Hung‐Lung , Ackerman Steven A. , Sokolik Irina N.
Published: February 2006

Numerical simulations have been carried out to understand the effects of overlapping cirrus clouds and mineral dust on the high‐spectral‐resolution infrared spectrum in the 600–2400 cm−1 region. A combination of the discrete ordinates radiative transfer and line‐by‐line models that account for the multiple scattering and monochromatic molecular absorption in the atmosphere is utilized to simulate the down‐looking infrared spectrum at the top of the atmosphere with a resolution of 0.2 cm−1. It is demonstrated that the spectral slope of the infrared radiance in the 800–1000 cm−1 region can be used to discriminate coexisting cirrus‐dust scenes from those associated only with cirrus clouds or dust alone. In a case for a cirrus cloud overlapping with a dust layer, the spectral features in the 1100–1200 cm−1 and 1400–1850 cm−1 regions can be potentially useful for retrieving the optical thicknesses of the dust layer and cirrus cloud, respectively.
Simulating the formation of Hurricane Isabel (2003) with AIRS data
Authors: Wu Liguang , Braun Scott A. , Qu John J. , Hao Xianjun
Published: February 2006

Using the AIRS retrieved temperature and humidity profiles, the Saharan Air Layer (SAL) influence on the formation of Hurricane Isabel (2003) is simulated numerically with the MM5 model. The warmth and dryness of the SAL (the thermodynamic effect) is assimilated by use of the nudging technique, which enables the model thermodynamic state to be relaxed to the profiles of the AIRS retrieved data for the regions without cloud contamination. By incorporating the AIRS data, MM5 better simulates the large‐scale flow patterns and the timing and location of the formation of Hurricane Isabel and its subsequent track. By comparing with an experiment without nudging of the AIRS data, it is shown that the SAL may have delayed the formation of Hurricane Isabel and inhibited the development of another tropical disturbance to the east. This case study confirms the argument by Dunion and Velden (2004) that the SAL can suppress Atlantic tropical cyclone activity by increasing the vertical wind shear, reducing the mean relative humidity, and stabilizing the environment at lower levels.
Long‐term variations of the electron slot region and global radiation belt structure
Authors: Fung Shing F. , Shao Xi , Tan Lun C.
Published: February 2006

We report the observations of changes of the nominal position of the quiet‐time radiation belt slot over the solar cycles. It has been found that the slot region, believed to be a result of enhanced precipitation losses of energetic electrons due to their interactions with VLF waves in the magnetosphere, tends to shift to higher L (∼3) during a solar maximum compared to its canonical L value of ∼2.5, which is more typical of a solar minimum. The solar‐cycle migration of the slot can be understood in terms of the solar‐cycle changes in ionospheric densities, which may cause the optimal wave‐particle interaction region during higher solar activity periods to move to higher altitudes and higher latitudes, thus higher L. Our analysis also suggests that the primary regions of wave‐particle interaction processes that result in the slot formation are located off of the magnetic equator.
1851–2004 annual heat budget of the continental landmasses
Authors: Huang Shaopeng
Published: February 2006

Changing climate is accompanied by changing energy in various climate system components including the continental landmasses. When the temperature at ground surface rises, more heat will be deposited to the rocks beneath the ground subsurface, whereas when ground surface temperature falls, certain amount of heat will escape from the ground into the atmosphere. Based on the land‐only global meteorological record, I analyze the annual heat budget of the world continents except for Antarctica. I show that between the period from 1851 to 2000 a total of 10.4 ZJ (Zetta‐Joules or 1021 J) of thermal energy had been absorbed by Africa, Asia, Australia, Europe, North America, and South America landmasses. An additional 1.34 ZJ of heat has been stored beneath the ground surface of these continents over the first four years of the 21st century from 2001 to 2004. The recent global climate change has led to an intensified heating in the continental landmasses.
Fast deep sinking in Mediterranean eddies
Authors: van Haren Hans , Millot Claude , Taupier‐Letage Isabelle
Published: February 2006

Large (up to 0.03 m s−1) downward vertical water velocities (w) are observed using yearlong moored ADCP at ∼2400 m in the deep Mediterranean Sea's Algerian basin. Once every 2–3 months, ∣w∣ rapidly increases to O(0.01 ± 0.002 m s−1) before slowly decreasing during a few weeks, in association with the passage of mesoscale eddies formed nearby. These amplitudes of negative w are O(100) times larger than those commonly linked to mesoscale eddies near the surface (subduction), and O(10) times larger than settling velocities for marine snow. Our observations suggest that mesoscale eddies, which are important for biological productivity near the surface, can also convect nearly fresh material down to the bottom (∼3000 m there) within a few days.
Rate of solar insolation change and the glacial/interglacial transition
Authors: Ji Junfeng , Balsam William , Chen Xing , Chen Jun , Chen Yang , Wang Hongtao
Published: February 2006

Climate changes are driven largely by variations in the distribution of solar insolation associated with changes in the Earth's orbital parameters. Here we define the rate of solar insolation change (RSIC) as a parameter to evaluate and quantify solar heating changes through time. We propose that RSIC may control the timing of transitions between warm and cold periods through its control on the rate of climate changes. Specifically, the glacial/interglacial transitions took place when the 65°N July insolation experienced the most rapid changes; interglacials start with a maximum positive RSIC and end with a maximum negative RISC. The RSIC curve thus provides a new astronomically tuned method for dating interglacials. The 65°N July RISC curves average a 4.7 ky lead compared to ice sheet changes as indicated by Bassinot et al. [1994] for the last 0.9 Ma, possibly implying a more rapid response of monsoonal climate to the insolation heating.
Aminoguanidine prevents arterial stiffening and cardiac hypertrophy in streptozotocin‐induced diabetes in rats
Authors: Chang Kuo‐Chu , Hsu Kwan‐Lih , Tseng Chuen‐Den , Lin Yue‐Der , Cho Yi‐Li , Tseng Yung‐Zu
Published: February 2006

The formation of advanced glycation endproducts (AGEs) on collagen within the arterial wall may be responsible for the development of diabetic vascular injury. This study was to examine the role of aminoguanidine (AG), an inhibitor of AGEs formation, in the prevention of arterial stiffening and cardiac hypertrophy in streptozotocin (STZ) induced diabetes in rats.

Diabetes was induced in animals by a single tail vein injection with 65 mg kg−1 STZ. After confirmation of the development of hyperglycemia (2 days later), rats were treated for 8 weeks with AG (daily peritoneal injections of 50 mg kg−1) and compared with the age‐matched untreated diabetic controls.

After exposure to AG, the STZ‐diabetic rats showed no alterations in cardiac output, aortic pressure profiles, total peripheral resistance, and aortic characteristic impedance.

By contrast, treatment of this experimental diabetes with AG resulted in a significant increase in wave transit time (τ), from 20.4±0.6 to 24.7±0.5 ms (P<0.05) and a decrease in wave reflection factor (Rf), from 0.78±0.04 to 0.53±0.02 (P<0.05). The decreased Rf associated with the increased τ suggest that AG may retard the diabetes‐induced augmentation in systolic load of the left ventricle coupled to its arterial system.

Meanwhile, the diminished ratio of left ventricular weight to body weight suggests that prevention of the diabetes‐related cardiac hypertrophy by AG may correspond to the drug‐induced decline in aortic stiffening.

Glycation‐derived modification on aortic collagen was also found to be enhanced in rats with diabetes (+65.3%, P<0.05) and the advanced glycation process was retarded by AG treatment.

We conclude that long‐term administration of AG to the STZ‐treated rats imparts significant protection against the diabetes‐derived deterioration in vascular dynamics, at least partly through inhibition of the AGEs accumulation on collagen in the arterial wall.

British Journal of Pharmacology (2006) 147, 944–950. doi:10.1038/sj.bjp.0706684
Co‐administration of glutathione and nitric oxide enhances insulin sensitivity in Wistar rats
Authors: Guarino Maria P , Macedo M Paula
Published: February 2006

The liver modulates insulin sensitivity through a prandial‐dependent mechanism that requires activation of the hepatic parasympathetic nerves, hepatic nitric oxide (NO) and hepatic glutathione (GSH). We tested the hypothesis that co‐administration of GSH and NO to the liver enhances insulin sensitivity in a GSH and NO dose‐dependent manner.

24 h fasted Wistar rats were used. Hepatic GSH was supplemented by administration of glutathione monoethylester (GSH‐E; 0.1/0.25/0.5/1/2 mmol kg−1) and 3‐morpholinosidnonimine (SIN‐1; 5/10 mg kg−1) was used as a NO donor. The drugs were administered either systemically (i.v.) or intraportally (i.p.v.). Insulin sensitivity was assessed using a transient euglycemic clamp.

Neither GSH‐E nor SIN‐1 increased insulin sensitivity when administered alone, both i.v. and i.p.v. Moreover, changes in insulin sensitivity were not observed when GSH‐E was administered i.v. followed by either i.v. or i.p.v. SIN‐1 at any of the doses tested. However, i.p.v. administration of GSH‐E followed by i.p.v. SIN‐1 10 mg kg−1 significantly increased insulin sensitivity in a GSH‐E dose‐dependent manner: 26.1±9.4% after 0.1 mmol kg−1 GSH‐E; 44.6±7.9% after 0.25 mmol kg−1 GSH‐E; 59.4±15.1% after 0.5 mmol kg−1 GSH‐E; 138.9±12.7% after 1 mmol kg−1 GSH‐E and 117.3±29.2% after a dose of 2 mmol kg−1 (n=23, P<0.005).

Our results confirm that insulin sensitivity is enhanced in a dose‐dependent manner by co‐administration of NO and GSH donors to the liver.

British Journal of Pharmacology (2006) 147, 959–965. doi:10.1038/sj.bjp.0706691
Diffusion length and junction spectroscopy analysis of low-temperature annealing of electron irradiation-induced deep levels in 4H-SiC
Authors: Castaldini A. , Cavallini A. , Rigutti L. , Pizzini S. , Le Donne A. , Binetti S.
Published: February 2006

The effects of low-temperature annealing in 8.2MeV electron-irradiated 4H-SiC Schottky diodes were investigated. Deep-level transient spectroscopy and minority-carrier diffusion length (Ld) measurements were carried out on not-irradiated samples and on irradiated samples before and after thermal treatments up to T=450°C. We found that several deep levels in the upper half band gap (S1 with enthalpy ET=0.27eV, S2 with ET=0.35eV, S4 with ET=0.71eV, and S5 with ET=0.96eV) anneal out or modify at temperature values lower or equal to T=450°C, whereby their progressive annealing out is accompanied by a net increase of Ld, up to 50% of the value in the as-irradiated sample. We drew some conclusions regarding the microscopic nature of the defects related to the deep levels, according to their annealing behavior.
Combined heat and mass transfer by laminar mixed convection flow from a vertical surface with induced magnetic field
Authors: Chaudhary R. C. , Sharma Bhupendra Kumar
Published: February 2006

The mixed convection flow over a continuously moving porous vertical plate under the combined buoyancy effects of thermal and mass diffusion has been studied under the action of transverse applied magnetic field taking into account the induced magnetic field, when the plate is subjected to constant heat and mass fluxes. Solutions for the velocity field, temperature distribution, concentration distribution, induced magnetic field and current density are obtained using perturbation technique. Expressions for shear stress, Nusselt number and Sherwood number are also obtained. Its apparent that the effect of Grashof number (Gr) on temperature distribution is significantly greater than the magnetic parameter and Schmidt number and the temperature distribution remains more for Gr<0 than that of Gr>0 for both air and water. It is found that the shear stress decreases with increasing Prandtl number (Pr).
Ionization by impact electrons in solids: Electron mean free path fitted over a wide energy range
Authors: Ziaja Beata , London Richard A. , Hajdu Janos
Published: February 2006

We propose a simple formula for fitting the electron ionization mean free paths in solids both at high and at low electron energies. The free-electron-gas approximation used for predicting electron mean free paths is no longer valid at low impact energies [(E−EF)<50eV], as the band structure effects become significant at those energies. Therefore, we include the results of band structure calculations in our fit. Finally, we apply the fit to nine elements and two compounds.
Microstructural properties of solution-deposited La0.7Sr0.3MnO3 and LaMnO3 thin films
Authors: Kartopu G. , Es-Souni M.
Published: February 2006

The microstructural properties of solution-deposited La0.7Sr0.3MnO3 and nondoped LaMnO3 films have been studied. Several factors such as the choice of substrate, method of surface cleaning, annealing atmosphere, and precursor solution concentration were considered. Films with smoother surfaces were observed on SrTiO3 (100) and LaAlO3 (100) crystals, due to the near matching of the film-substrate lattice constants and thermal-expansion coefficients. In contrast, substrates such as Si (100) yield films with a rougher morphology. Variations in the crystalline quality and surface morphology of the films were demonstrated, simply by altering the precursor solution concentration and the surface condition of substrate. The local structure of the films was studied by Raman spectroscopy, which indicated enrichment in the oxygen content, differing from ideal oxygen stoichiometry (or from films annealed in inert gas atmosphere). This latter effect was shown to be more effective in the case of LaMnO3, where a structural transition from rhombohedral to orthorhombic was observed by changing the annealing atmosphere from ambient air to pure N2 gas, and is suggested to be the main origin of the anomalous conductivity increase reported in the literature in air or O2-annealed manganite films with respect to stoichiometric bulk La1−x(Sr,Ca)xMnO3.
Electrical description of a magnetic pole enhanced inductively coupled plasma source: Refinement of the transformer model by reverse electromagnetic modeling
Authors: Meziani T. , Colpo P. , Rossi F.
Published: February 2006

The magnetic pole enhanced inductively coupled source (MaPE-ICP) is an innovative low-pressure plasma source that allows for high plasma density and high plasma uniformity, as well as large-area plasma generation. This article presents an electrical characterization of this source, and the experimental measurements are compared to the results obtained after modeling the source by the equivalent circuit of the transformer. In particular, the method applied consists in performing a reverse electromagnetic modeling of the source by providing the measured plasma parameters such as plasma density and electron temperature as an input, and computing the total impedance seen at the primary of the transformer. The impedance results given by the model are compared to the experimental results. This approach allows for a more comprehensive refinement of the electrical model in order to obtain a better fitting of the results. The electrical characteristics of the system, and in particular the total impedance, were measured at the inductive coil antenna (primary of the transformer). The source was modeled electrically by a finite element method, treating the plasma as a conductive load and taking into account the complex plasma conductivity, the value of which was calculated from the electron density and electron temperature measurements carried out previously. The electrical characterization of the inductive excitation source itself versus frequency showed that the source cannot be treated as purely inductive and that the effect of parasitic capacitances must be taken into account in the model. Finally, considerations on the effect of the magnetic core addition on the capacitive component of the coupling are made.
Design of one-dimensional composite photonic crystals with an extended photonic band gap
Authors: Tolmachev V. A. , Perova T. S. , Berwick K.
Published: February 2006

A technique for photonic band gap (PBG) extension based on mixing photonic crystals with different lattice constants or filling factors is suggested. For the design of photonic crystals with maximal PBG extension the gap map imposition method is utilized. Gap maps for composite photonic crystals based on Si-air structures are calculated and used to predict optimal structures for fabrication.
An analytical model for nanoscale electrothermal probe recording on phase-change media
Authors: Aziz Mustafa M. , Wright C. David
Published: February 2006

Scanning probe memories are now emerging as a means of achieving nanoscale resolution data storage. The use of microscopic conductive tips in contact with a phase-change material to record data as amorphous and crystalline marks is one such approach, making use of the large difference in electrical conductivity between the two phases to distinguish between two binary states on replay and hence provide a memory function. The writing process is complex and involves electronic, thermal, and phase-change processes that are difficult to model and study except using numerical techniques. A simplified analytical model of electrothermal writing by probe on a basic two-layer phase-change structure is developed here, and used to predict the required voltage levels for recording and the expected diameters of recorded crystalline and amorphous marks. A simplified model of cooling and solidification was also developed to study the cooling rates during amorphization. The predictions are shown to be in agreement with published experimental measurements and numerical simulations. The developed analytical models were extended to investigate the effects of introducing coating layers on recording voltage levels, to study the depth profiles of recorded marks, and to derive expressions for the capacitance and resistance of the phase-change layer that contribute to the transient behavior of the recording system.
Strong flexoelectric behavior in bimesogenic liquid crystals
Authors: Coles H. J. , Clarke M. J. , Morris S. M. , Broughton B. J. , Blatch A. E.
Published: February 2006

In this paper, we demonstrate strong flexoelectric coupling in bimesogenic liquid crystals. This strong coupling is determined via the flexoelectro-optic effect in chiral nematic liquid crystals based on bimesogenic mixtures that are doped with low concentrations of high twisting power chiral additive. Two mixtures were examined: one had a pitch length of p∼300nm, the other had a pitch length of p∼600nm. These mixtures exhibit enantiotropic chiral nematic phases close to room temperature. We found that full-intensity modulation, that is, a rotation of the optic axis of 45° between crossed polarizers, could be achieved at significantly lower applied electric fields (E<5Vμm−1) than previously reported. In fact, for the condition of full-intensity modulation, the lowest electric-field strength recorded was E=2Vμm−1. As a result of a combination of the strong flexoelectric coupling and a divergence in the pitch, tilt angles of the optic axis up to 87°, i.e., a rotation of the optic axis through 174°, were observed. Furthermore, the flexoelastic ratios, which may be considered as a figure-of-merit parameter, were calculated from the results and found to be large, ranging from 1.3to2C∕Nm for a temperature range of up to 40°C.
Subband and transport calculations in double n-type δ-doped quantum wells in Si
Authors: Rodriguez-Vargas I. , Gaggero-Sager L. M.
Published: February 2006

The Thomas-Fermi approximation is implemented in two coupled n-type δ-doped quantum wells in Si. An analytical expression for the Hartree-Fock potential is obtained in order to compute the subband level structure. The longitudinal and transverse levels are obtained as a function of the impurity density and the interlayer distance. The exchange-correlation effects are analyzed from an impurity density of 8×1012to6.5×1013cm−2. The transport calculations are based on a formula for the mobility, which allows us to discern the optimum distance between wells for maximum mobility.
Temperature dependence of the coupling between n-type δ-doping region and quantum dot assemblies
Authors: Fekete D. , Dery H. , Rudra A. , Kapon E.
Published: February 2006

We present experimental evidence that at room temperature the main coupling mechanism between an n-type δ-doping region and an adjacent plane of dots is energy-conserving electron-electron scattering, in which a hot electron in the δ-doping region transfers energy to a deeply confined electron in that region and relaxes to the quantum dot. We demonstrate that at room temperature the increased capture cross section due to electron-electron scattering considerably enhances the injection into the quantum dots with a certain size and thus reduces the phonon bottleneck in quantum dot assemblies for the quantum dots that interact with the δ-doping region. We identify different temperature-dependent injection schemes by comparing the photoluminescence of dilute and dense assemblies with the corresponding photoluminescence of similar structures including n-type δ-doping regions adjacent to the dots’ plane.
Regular perturbation solution of the Elenbaas-Heller equation
Authors: Shaw B. D.
Published: February 2006

The Elenbaas-Heller equation is nondimensionalized and solved using regular perturbation theory to provide closed-form analytical solutions to describe structures of cylindrically symmetrical steady electric arc discharges with negligible radiant heat transfer. Based on available data, it is assumed that the electrical conductivity varies with the heat-flux potential in an Arrhenius fashion. The leading-order solution is equivalent to an asymptotic solution proposed by Kuiken [J. Appl. Phys. 58, 1833 (1991)]. Higher-order terms are also derived in the present paper, and it is shown that quantitatively accurate analytical solutions can be developed when higher-order terms are included. Analysis shows that appreciable Joule heating is restricted to an inner zone when a dimensionless parameter is large relative to unity, leading to arc-channel models suggested by previous investigators.
Photoresponse of gated p-silicon field emitter array and correlation with theoretical models
Authors: Liu Kendrick X. , Chiang Chin-Jen , Heritage Jonathan P.
Published: February 2006

Improved fabrication and conditioning techniques for gated p-Si field emitter arrays (FEAs) (1×1mm2 in size with 50×50 emitters) greatly reduces the bulk damage and surface states. Consequently, only 0.9μA of the anode dark field-emission current was measured for 50V applied gate potential with a very low gate leakage current. At these low gate leakage currents, the transition between the tunneling-limited field-emission regime and the supply-limited saturation regime is clearly revealed in current-voltage plots. This transition is accompanied by a reduction in the anode current fluctuation. The standard deviation of the noise current drops from a few percent in the tunneling-limited regime to <1% in the supply limited regime at 50V. A photocurrent of 0.41mA was obtained for photoexcitation at 840nm wavelength. This corresponded to 40dB contrast ratio between the photocurrent and the dark current at room temperature. Additionally, our findings showed that surface states were fully depleted at low applied fields, the concentration of bulk defects was low and the area contributing to the dark current was confined to the emitter regions. In contrast, previously reported ungated Si field emitters had high concentrations of surface states and bulk defects. Furthermore, the contributing area to the dark current corresponded to the whole area of the device as opposed to only the emitter areas for a gated FEA. Photofield emission and dark current measurements from our gated p-Si FEA correlate well to theoretical models without requiring cooling to liquid-nitrogen temperatures.
Structure-induced magnetic anisotropy in the Fe(110)∕Mo(110)∕Al2O3(112¯0) system
Authors: Fraune M. , Hauch J. O. , Güntherodt G. , Laufenberg M. , Fonin M. , Rüdiger U. , Mayer J. , Turban P.
Published: February 2006

Fe(110) films were epitaxially grown on sapphire substrates using a Mo(110) buffer layer in an ultrahigh-vacuum molecular-beam epitaxy system. The magnetic properties were examined ex situ by Brillouin light scattering and superconducting quantum interference device magnetometry. To determine the magnetic anisotropy constants the frequency of the Damon-Eshbach [J. Phys. Chem. Solids 19, 308 (1961)] surface spin-wave mode was measured as a function of the in-plane angle between the external magnetic field and the Fe[001] crystal axis. The angle-dependent frequency was fitted by a spin-wave model. We found that the easy axis of the cubic magnetocrystalline anisotropy K1 and an additional uniaxial in-plane anisotropy K‖(2) are aligned parallel to the in-plane Fe[001] axis for Fe-layer thicknesses from 0.8to37nm, with K1 increasing and K‖(2) decreasing with increasing Fe thickness. Possible origins of the observed uniaxial anisotropy are discussed.
Comparison of blended versus layered structures for poly(p-phenylene vinylene)-based polymer photovoltaics
Authors: Chasteen S. V. , Härter J. O. , Rumbles G. , Scott J. C. , Nakazawa Y. , Jones M. , Hörhold H.-H , Tillman H. , Carter S. A.
Published: February 2006

We characterize and compare blended and bilayered heterojunctions of polymer photovoltaic devices using poly[oxa-1,4-phenylene-1,2-(1-cyano)-ethenylene-2,5-dioctyloxy-1,4-phenylene-1,2-(2-cyano)-ethenylene-1,4-phenylene] (CN-ether-PPV) and poly[2,5-dimethoxy-1,4-phenylene-1,2-ethenylene-2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene-1,2-ethenylene] (M3EH-PPV) as electron- and hole-transporting polymers, respectively. We find that both blended and bilayered structures have substantially improved current densities (>3mA∕cm2) and power efficiencies (∼1% under white light) over neat films. Improved exciton dissociation at multiple interfaces and reduced recombination due to energy and charge transfers increases the charge-carrier collection in both types of heterojunction devices, but low electron mobilities in the polymers lead to low fill factors and reduced quantum efficiency (∼20%) that limit the power efficiency. Time-resolved photoluminescence reveals that for blended structures both the hole and electron-transporting polymers undergo efficient quenching with the exciton decay being dominated by the existence of two fast decay channels of 0.12 and 0.78ns that are assigned to interspecies charge transfer and account for the increased short-circuit current observed. For layers, these components are not as prevalent. This result indicates that greater exciton generation at the dissociating interface and more efficient charge collection in the thin layers is primarily responsible for the improved short-circuit current, a conclusion that is further supported by numerical simulations of the exciton generation rate and charge collection. We also report evidence for an intermediate exciplex state in both types of structures with the greatest yield for blends with 50wt% of CN-ether-PPV. Overall, the improved performance is due to different processes in the two structures; efficient bulk exciton quenching and charge transfer in blends and enhanced exciton generation and charge collection in layers. The optimization of each photovoltaic heterostructured device relies on this understanding of the mechanisms by which each material architecture achieves high power efficiencies.
Computational study of Ge and Sn doping of CdTe
Authors: Jaffe John E.
Published: February 2006

The formation and ionization energies of substitutional Ge and Sn dopants in CdTe are calculated in a supercell model within the local-density approximation to density-functional theory. Doping on both the Cd and Te sublattices is considered, but the formation energy of both defects is predicted to be much lower on the Cd site under most growth conditions. The Ge and Sn on the Cd sites are predicted to be deep donors and hole traps with defect ionization levels near the midgap, with Ge slightly lower than Sn, in good agreement with experiments. The Ge and Sn on the Te sites are predicted to be shallow acceptors.
Thermoelastic finite element modeling of laser generation ultrasound
Authors: Xu Baiqiang , Shen Zhonghua , Wang Jijun , Ni Xiaowu , Guan Jianfei , Lu Jian
Published: February 2006

Thermoelastic finite element modeling of laser-generated ultrasound in aluminum plates is presented based on a numerical formulation for the transient response in terms of the characteristics of the source of the thermoelastic waves. The model accounts for the effects of thermal diffusion, as well as the finite width and duration of the laser source. The stress can be related to the laser energy and material properties. The numerical results indicate that the temperature dependence of the thermophysical parameters has a significant influence on the laser-generated surface-acoustic waves with high frequencies.
In situ stress evolution of Co films sputtered onto oxidized Si (100) substrates
Authors: Pletea M. , Brückner W. , Wendrock H. , Kaltofen R. , Koch R.
Published: February 2006

The stress of magnetron-sputtered Co films of thicknesses up to 300 nm has been investigated in a wide range of sputter pressures (0.05-6 Pa) by a laser-based optical bending-beam setup. To correlate the thickness dependence of the stress with changes in the microstructure, the film morphology was investigated by focused ion beam, scanning electron microscopy, and atomic force microscopy. At all of the chosen sputter pressures the film stress is tensile. At low sputter pressures its evolution with film thickness can be related to the Volmer-Weber growth mode of medium-mobility metals and is similar to that of sputtered Cu films concerning nuclei density, island size, and island growth. At higher sputter pressures a transition to columnar grain growth takes place, accompanied by a decrease of the film density and an increase of the electrical resistance. The evolution of stress and microstructure with film thickness is discussed in the context of the stress models proposed in the literature.
Annealing temperature dependence of capacitance-voltage characteristics in Ge-nanocrystal-based nonvolatile memory structures
Authors: Park C. J. , Cho H. Y. , Kim S. , Choi Suk-Ho , Elliman R. G. , Han J. H. , Kim Chungwoo , Hwang H. N. , Hwang C. C.
Published: February 2006

The annealing temperature (TA) dependence of capacitance-voltage (C-V) characteristics has been studied in metal-oxide-semiconductor structures containing Ge nanocrystals (NCs) produced by ion implantation and annealing. These structures are of interest for application as nonvolatile memory and TA is shown to have a strong influence on the C-V hysteresis. This behavior is shown to be correlated with structural changes of the Ge NCs which have been characterized by synchrotron-radiation photoemission spectroscopy. Specifically, well-defined C-V characteristics with large hysteresis were found only for annealing temperatures greater than 950 °C where Ge nanocrystals are known to form. In this temperature regime, transmission electron microcopy and energy dispersive x-ray spectroscopy demonstrate the existence of regularly arranged Ge NCs of approximately 3–5 nm diameter located around 6.7 nm from the interface.
Perpendicular giant magnetoresistance of electrodeposited Co∕Cu-multilayered nanowires in porous alumina templates
Authors: Tang X.-T. , Wang G.-C. , Shima M.
Published: February 2006

The giant magnetoresistance (GMR) of multilayered Co∕Cu nanowires potentiostatically electrodeposited inside the pores of an anodized alumina template was studied in the current perpendicular to the plane (CPP) geometry. The maximum magnetoresistance change of 13.5% was observed for Co(8nm)∕Cu(10nm) nanowires at room temperature. The interfacial roughness and/or an intermixing between Co and Cu layers were varied by changing the Cu deposition potential. However, the CPP-GMR value only slightly decreases as the Cu deposition potential increases to the positive value. This indicates that the interfacial roughness and/or intermixing are not a crucial factor in determining the CPP-GMR value of the Co∕Cu nanowires, which is argued to be due to the uncoupled magnetic layers. The x-ray diffraction shows that Co∕Cu nanowires with 300nm diameter have a face-centered-cubic structure with a strong (111) texture along the wire axes; their magnetic easy axes are perpendicular to the wire axes as determined from the CPP-GMR curve. The effects of the interface roughness and/or an intermixing between Co and Cu layers and their thickness variation on the CPP-GMR are discussed.