bluuebunny/crossref_metadata_2025 huggingface dataset:
Variations in estimates of underweight, stunting, wasting, overweight and obesity in children from Argentina comparing three growth charts
Authors: Padula Gisel , Seoane Analía I , Salceda Susana A
Published: March 2012

Objective

To compare estimates of underweight, stunting, wasting, overweight and obesity based on three growth charts.

Design

Cross-sectional study to estimate weight-for-age, length/height-for-age and weight-for-height comparing the 2006 WHO Child Growth Standards (‘the WHO standards’), the 1977 National Center for Health Statistics (NCHS) international growth reference (‘the NCHS reference’) and the 1987 Argentine Pediatric Society Committee of Growth and Development reference (‘the APS reference’). Cut-off points were defined as mean values ±2 sd. Epi-Info software version 6·0 (Centers for Disease Control and Prevention) was used for statistical evaluations (χ2, P ≤ 0·05).

Setting

Greater La Plata conurbation, Buenos Aires, Argentina.

Subjects

A total of 2644 healthy, full-term children from 0 to 5 years of age.

Results

Prevalence of underweight was higher with the WHO standards than with the other references up to the first 6 months. For the rest of the ages, prevalence was lower with the WHO standards. Stunting prevalence was higher with the WHO standards at all ages. Prevalence of wasting was higher with the WHO standards compared with the NCHS reference up to the first 6 months and lower at 2–5 years of age. Overweight and obesity prevalences were higher with the WHO standards at all ages.

Conclusions

The new WHO standards appear to be a solid and reliable tool for diagnosis and treatment of nutritional diseases, also being the only one built with infants fed according to WHO recommendations. Therefore, our results support the decision of the National Ministry of Health about the utilization of the new WHO standards to monitor the nutritional status of Argentinean children aged less than 5 years.
Sleep disturbance in relatives of palliative patients cared for at home
Authors: Carlsson Maria E.
Published: March 2012

Objective:

The aim of the present pilot study was to investigate insomnia, sleep quality, and daytime sleepiness in relatives of dying patients cared for at home.

Method:

The study has a descriptive, comparative, and cross-sectional design. The sample consisted of relatives of patients cared for through palliative home care in Uppsala County on 3 specific days. Relatives completed a questionnaire consisting of demographic questions, and items from the Insomnia Severity Index (ISI), the Epworth Sleepiness Scale (ESS), and the Richard Campell Sleep Questionnaire (RCSQ).

Results:

Seventy-five relatives answered the questionnaire. The average total ISI score was 9.6, with 23% reporting moderate or severe clinical insomnia. The mean sleep duration was 6.5 hours, the mean assessed need of sleep was 8 hours, and the mean discrepancy was 1 hour. The total mean ESS score was 5.6 and only 15% of respondents reported excessive daytime sleepiness. Four percent scored very poor sleep quality, whereas 39% scored very good sleep quality (RCSQ). Two general age- and gender-related patterns were observed. Negative correlations were found between age and sleep problems, with younger relatives reporting more insomnia problems and more daytime sleepiness than did older relatives. The other general pattern was that womens' sleep quality was significantly inferior to that of men. A significant positive correlation was found between ISI and ESS, but not between RCSQ and ESS.

Significance of results:

The picture of the relatives' sleep condition is fairly complex. A minority reported clinical insomnia problems or excessive daytime sleepiness, and 73% reported getting less sleep than they wanted.
Does the cancer patient's disease stage matter? A comparative study of caregivers' mental health and health related quality of life
Authors: Grov Ellen Karine , Valeberg Berit Taraldsen
Published: March 2012

Objective:

Cancer affects both patients and their caregivers. Caregiver burden may change during different stages of the patients' cancer trajectory. Limited research has focused on the impact of being a caregiver, assessed by the caregiver's mental health and quality of life (QOL) during the curative and the palliative phases of the patient's disease. The aim of this study is to compare caregivers of cancer patients during the curative and a palliative phases with respect to their mental health and health-related QOL.

Method:

This descriptive, cross-sectional study combines data from two studies. The first group consists of caregivers of patients with cancer in the late palliative phase and the second group consists of caregivers of outpatients with cancer who suffer from pain and/or use analgesics. Data were collected by means of standardized measures and analyzed with descriptive statistics.

Results:

Based on this material, no significant differences in mental health and health- related QOL were revealed for caregivers of cancer patients in the palliative and the curative phases, respectively. Neither education level in the caregivers, nor the patients' functional status influenced caregivers' mental health or QOL. Younger caregivers seem to have better physical QOL.

Significance of results:

Being caregivers of cancer patients seems to have a similar pattern of impact on caregivers' mental health and quality of life regardless of the patient's disease stage. We share some reflections about the way in which the cancer stage is divided and the appropriateness of such selection for measuring caregivers' mental health and QOL. Additionally, we discuss the use of generic instruments for measuring specific contexts and particular samples.
Cancer and post-traumatic stress disorder: Diagnosis, pathogenesis and treatment considerations
Authors: Rustad James K. , David Daniella , Currier M. Beatriz
Published: March 2012

Objective:

The purpose of this article was to review the literature regarding diagnosis, pathogenesis, and treatment of post-traumatic stress disorder (PTSD) associated with cancer.

Method:

We surveyed studies examining the validity of diagnostic scales commonly used to measure PTSD in patients with cancer. Neurobiological underpinnings of PTSD and cancer, including inflammation as the physiological mechanism linking these comorbidities, were examined. Psychopharmacologic and psychotherapeutic treatment of PTSD symptoms in patients with cancer was reviewed. In addition, potential drug–drug interactions between psychotropic medications commonly used to treat PTSD and anti-cancer agents were reviewed.

Results:

Multiple studies demonstrated the validity of the PTSD Checklist Civilian Version (PCL-C) in diagnosing PTSD in patients with cancer. Research has shown that PTSD as defined in DSM-IV appears to be a better model for conceptualizing distress in patients with cancer than a generalized “distress” model. Epidemiologic studies have shown an increased incidence of PTSD associated with cancer; however, literature regarding characteristics of PTSD in patients with cancer is cross-sectional in nature.

Significance of results:

Future research focusing on longitudinal, prospective studies to identify patients at risk, determine causal or aggravating factors, and develop preventive interventions is needed. Further study of PTSD in patients with cancer may help increase recognition of this disorder, optimize treatment, and enhance the quality of life of these individuals.
Farallon slab detachment and deformation of the Magdalena Shelf, southern Baja California
Authors: Brothers Daniel , Harding Alistair , González‐Fernández Antonio , Holbrook W. Steven , Kent Graham , Driscoll Neal , Fletcher John , Lizarralde Dan , Umhoefer Paul , Axen Gary
Published: March 2012

Subduction of the Farallon plate beneath northwestern Mexico stalled by ∼12 Ma when the Pacific‐Farallon spreading‐ridge approached the subduction zone. Coupling between remnant slab and the overriding North American plate played an important role in the capture of the Baja California (BC) microplate by the Pacific Plate. Active‐source seismic reflection and wide‐angle seismic refraction profiles across southwestern BC (∼24.5°N) are used to image the extent of remnant slab and study its impact on the overriding plate. We infer that the hot, buoyant slab detached ∼40 km landward of the fossil trench. Isostatic rebound following slab detachment uplifted the margin and exposed the Magdalena Shelf to wave‐base erosion. Subsequent cooling, subsidence and transtensional opening along the shelf (starting ∼8 Ma) starved the fossil trench of terrigenous sediment input. Slab detachment and the resultant rebound of the margin provide a mechanism for rapid uplift and exhumation of forearc subduction complexes.
The relation between subauroral polarization streams, westward ion fluxes, and zonal wind: Seasonal and hemispheric variations
Authors: Wang Hui , Lühr Hermann , Ma Shu Y.
Published: March 2012

We investigate the seasonal variation of the relation between SAPS (subauroral polarization streams) peak ion velocity and zonal wind velocity with coordinated DMSP and CHAMP satellite observations in both hemispheres, separately for Kp < 4 and Kp ≥ 4 geomagnetic conditions. Both SAPS and westward zonal wind peak almost at the same latitude. However, SAPS and zonal wind peak velocities show significantly different seasonal variations. SAPS peak velocities are larger in winter as compared to summer, while zonal wind peak velocities have opposite behavior, larger in summer and smaller in winter, which is valid in both hemispheres and for both geomagnetic activity levels. We reveal, for the first time, that SAPS peak westward ion fluxes, the product of SAPS ion velocity and ion density, exhibit similar seasonal variation as the zonal wind. The results indicate that the effect of SAPS on the zonal wind depends strongly on local ion densities. A linear relationship between SAPS ion fluxes and zonal wind is derived for both hemispheres, which is practically independent of geomagnetic activity. The scaling factor between ion flux and wind velocity is about the same in both hemispheres. Conversely, the background westward wind velocity (bias value in linear equation) is by about 100 m/s higher in the Northern than in the Southern Hemisphere. We attribute this difference to the effect of the large offset between geographic and magnetic poles in the Southern Hemisphere.
Particle simulations of whistler‐mode rising‐tone emissions triggered by waves with different amplitudes
Authors: Hikishima Mitsuru , Omura Yoshiharu
Published: March 2012

We perform self‐consistent electromagnetic particle simulations to analyze whistler‐mode triggered emissions in the magnetosphere. The whistler‐mode triggering waves with different wave amplitudes and a constant frequency are injected at the equator. With triggering wave amplitudes greater than the threshold for the nonlinear wave growth, rising‐tone emissions are successfully excited near the equator. The detailed time evolutions of amplitudes and frequencies of the rising‐tone emissions show similar development. A recent theoretical study found the optimum amplitude of triggering waves for rising‐tone emissions. The optimum amplitude condition is confirmed by the simulations. A triggering wave with an amplitude much greater than the optimum amplitude cannot trigger a rising emission. In a process where triggered emissions develop, phase‐organized resonant electrons clearly appear in the velocity‐phase space, contributing to the nonlinear wave growth. The simulation study shows that amplitudes and frequency sweep rates of triggered emissions do not depend on the amplitude of a triggering wave.
Seasonal coupling and de‐coupling of net calcification rates from coral reef metabolism and carbonate chemistry at Ningaloo Reef, Western Australia
Authors: Falter James L. , Lowe Ryan J. , Atkinson Marlin J. , Cuet Pascale
Published: March 2012

Rates of net production, net calcification, and nutrient uptake were measured in a coral‐dominated reef flat community on Ningaloo Reef in northwestern Australia under seasonally minimum and maximum light levels. Daily integrated light decreased twofold while water temperatures remained relatively constant increasing by only 1°C on average from summer to winter. Rates of daily community gross primary production (GPP) were only 33% ± 9% higher in summer than in winter (1400 ± 70 versus 1050 ± 60 mmol C m−2 d−1), far less than the twofold seasonal changes reported for most shallow reef communities. Rates of daily community net calcification (Gnet) were not significantly different between seasons (190 ± 40 mmol CaCO3 m−2 d−1 in summer versus 200 ± 10 mmol CaCO3 m−2 d−1 in winter). The average rate of total nitrogen uptake (dissolved + particulate) was also not significantly different between summer and winter (8.3 ± 3.8 versus 6.6 ± 3.4 mmol N m−2 d−1, respectively), despite evidence of sporadically high nitrate uptake in both seasons. In summer, rates of hourly net calcification (gnet) were linearly correlated with diurnal changes in net production, pH, and aragonite saturation state (Ωar); and were mostly correlated with light except at mid‐day under heavy cloud cover. However, in winter,gnet was independent of diurnal changes in light, net production, pH, and Ωar indicating that the reef flat community had possibly reached a threshold above which rates of net calcification were insensitive to diurnal changes in their environment.
Enhanced upper ocean stratification with climate change in the CMIP3 models
Authors: Capotondi Antonietta , Alexander Michael A. , Bond Nicholas A. , Curchitser Enrique N. , Scott James D.
Published: March 2012

Changes in upper ocean stratification during the second half of the 21st century, relative to the second half of the 20th century, are examined in ten of the CMIP3 climate models according to the SRES‐A2 scenario. The upper ocean stratification, defined here as the density difference between 200 m and the surface, is larger everywhere during the second half of the 21st century, indicative of an increasing degree of decoupling between the surface and the deeper oceans, with important consequences for many biogeochemical processes. The areas characterized by the largest stratification changes include the Arctic, the tropics, the North Atlantic, and the northeast Pacific. The increase in stratification is primarily due to the increase in surface temperature, whose influence upon density is largest in the tropical regions, and decreases with increasing latitude. The influence of salinity upon the stratification changes, while not as spatially extensive as that of temperature, is very large in the Arctic, North Atlantic and Northeast Pacific. Salinity also significantly contributes to the density decrease near the surface in the western tropical Pacific, but counteracts the negative influence of temperature upon density in the tropical Atlantic.
Upwelling source depth in the presence of nearshore wind stress curl
Authors: Jacox M. G. , Edwards C. A.
Published: March 2012

The influence of nearshore wind stress curl on the relative partitioning of bottom boundary layer (BBL) and interior transport within an idealized, two‐dimensional coastal upwelling system is studied theoretically and using a numerical model. A nearshore reduction in upwelling favorable wind stress amplitude (1) reduces the width of the inner shelf, (2) reduces the local wind‐driven Ekman transport, and (3) increases the cross‐shelf momentum flux divergence. Relative BBL transport, defined as the transport entering the surface mixed layer (SML) from the BBL divided by offshore transport in the SML, decreases under reduced nearshore wind stress. This effect is dominated by the reduced local SML Ekman transport and to a lesser degree by local curl of surface and bottom stresses. We consider the quantitative impact for a range of shelf slopes, stratifications, and wind stress curl scales. The relative contribution of bottom boundary layer transport co‐varies with upwelling source depth and is therefore expected to alter nutrient fluxes into the euphotic zone as well as the resultant biological response.
Localized seismic anisotropy associated with long‐term slow‐slip events beneath southern Mexico
Authors: Song Teh‐Ru Alex , Kim YoungHee
Published: March 2012

Slow slip events (SSEs) are recently discovered in the transition zone downdip of the locked zone where megathrust earthquakes repeatedly occur at subduction zone interface. Structural changes from the locked zone to the transition zone and the nature of in situ deformation in the transition zone, however, remain unclear. We model teleseismic converted P‐to‐S waves to investigate seismic structural transition and anisotropy associated with shear deformation near the deep locked zone and the transition zone beneath southern Mexico. The deep locked zone appears to be consistent with normal oceanic crust velocity. In the transition zone, we find that seismic anisotropy larger than 5% is associated with the ultra‐slow velocity layer (USL) near the top of the subducted oceanic crust. The foliation plane is plunging 20 ± 10 degrees steeper than the plate interface, and it is consistent with crystallographic preferred orientation developed in S‐C mylonites. We suggest that long‐term SSEs likely coincide with a near‐lithostatic semiductile talc‐rich shear zone.
JNK regulates the photic response of the mammalian circadian clock
Authors: Yoshitane Hikari , Honma Sato , Imamura Kiyomichi , Nakajima Hiroto , Nishide Shin‐ya , Ono Daisuke , Kiyota Hiroshi , Shinozaki Naoya , Matsuki Hirokazu , Wada Naoya , Doi Hirofumi , Hamada Toshiyuki , Honma Ken‐ichi , Fukada Yoshitaka
Published: March 2012

The posttranslational regulation of mammalian clock proteins has been assigned a time‐keeping function, but seems to have more essential roles. Here we show that c‐Jun N‐terminal kinase (JNK), identified by inhibitor screening of BMAL1 phosphorylation at Ser 520/Thr 527/Ser 592, confers dynamic regulation on the clock. Knockdown of JNK1 and JNK2 abrogates BMAL1 phosphorylation and lengthens circadian period in fibroblasts. Mice deficient for neuron‐specific isoform JNK3 have altered behavioural rhythms, with longer free‐running period and compromised phase shifts to light. The locomotor rhythms are insensitive to intensity variance of constant light, deviating from Aschoff's rule. Thus, JNK regulates a core characteristic of the circadian clock by controlling the oscillation speed and the phase in response to light.
Neurl4, a novel daughter centriole protein, prevents formation of ectopic microtubule organizing centres
Authors: Li Ji , Kim Sehyun , Kobayashi Tetsuo , Liang Feng‐Xia , Korzeniewski Nina , Duensing Stefan , Dynlacht Brian D
Published: March 2012

Here we identify Neuralized homologue 4 (Neurl4) as a protein that interacts with CP110, a centrosomal protein that regulates centrosome duplication. Neurl4 uses a Neuralized homology repeat to preferentially localize to procentrioles and daughter centrioles. Neurl4 depletion results in ectopic microtubular organizing centres (MTOCs), leading to accumulation of CP110 and recruitment of a cohort of centrosomal proteins. We show that these ectopic MTOCs persist through mitosis and assemble aberrant mitotic spindles. Interestingly, Neurl4 promotes ubiquitylation of CP110, thereby destabilizing this protein. Our results indicate that Neurl4 counteracts accumulation of CP110, thereby maintaining normal centriolar homeostasis and preventing formation of ectopic MTOCs.
Integration of the scientific literature into the Semantic Web: Facts from biomedical data resources
Authors: Rebholz Dietrich , Croset Samuel , Grabmueller Christoph
Published: March 2012

Scientific literature is the primary resource for relevant and innovative information. The integration of the literature with other data resources in the biomedical research community generates overhead that can be avoided through the used of Semantic Web Technology generating openly accessible data. Projects such as SESL and CALBC have producted significant amount of data that that are ready for exploitation.The tutorial will teach different approaches on how to integrate the scientific literature with the content from biomedical databases, and will discuss the inferences that can be achieved. Furthermore, the tutorial will point to the resources that are ready for use and enable integration of the literature at your discretion. A good understanding of Semantic Web technology, ontologies, OWL and the existing biomedical data resources is advantageous to easily follow the tutorial.
Hypogonadism Secondary to Hyperprolactinaemia: Successful Treatment but Adverse Consequences
Authors: Narayanan R. , Bujawansa S. , Qureshi Z. , Rimmer M. , Heald A.
Published: March 2012

It is accepted that care must be taken in initiating testosterone replacement in hypogonadal individuals with historically low androgen levels. However less is reported about the influence of restoration of normal endogenous testosterone production on behaviour.

Here we report how the adverse sequelae of successful treatment of hypogonadism secondary to hyperprolactinaemia, manifesting as irritability and low threshold to aggression, were managed through a joint approach between psychiatrist and physician.
Comparison of electrostatic fins with piezoelectric impact hammer techniques to extend impulse calibration range of a torsional thrust stand
Authors: Pancotti Anthony P. , Gilpin Matthew , Hilario Martin S.
Published: March 2012

With the progression of high-power electric propulsion and high thrust-to-power propulsions system, thrust stand diagnostics require high-fidelity calibration systems that are accurate over a large-range of thrust levels. Multi-mode and variable Isp propulsion devices also require that a single stand be capable of measuring thrust from 10's of uNs to 100's of mNs. While the torsional thrust stand mechanic and diagnostics are capable of operating over such a large range, current pulsed calibration schemes are typically limited to a few orders of magnitude of dynamic range. In order to develop a stand with enough dynamic range, two separate calibration methods have been examined and compared to create a combined system. Electrostatic fin (ESF) and piezoelectric impact hammer (PIH) calibration systems were simultaneously tested on a large scale torsional thrust stand system. The use of the these two methods allowed the stand to be calibrated over four orders of magnitude, from 0.01 mNs to 750 mNs. The ESF system produced linear results within 0.52% from 0.01 mNs to 20 mNs, while the PIH system extended this calibration range from 10 mNs to 750 mNs with an error of 0.99%. The two calibration methods agreed within 4.51% over their overlapping range of 10–20 mNs.
Multi-objective stochastic dynamic economic emission dispatch enhancement by fuzzy adaptive modified theta particle swarm optimization
Authors: Bahmanifirouzi Bahman , Farjah Ebrahim , Niknam Taher
Published: March 2012

This paper presents a new method based on fuzzy adaptive modified theta particle swarm optimization to investigate the multiobjective day-ahead dynamic economic emission dispatch (DEED) problem considering the effect of wind power generators. The proposed algorithm concurrently reduces the total fuel cost as well as the total emission during the optimization process. Besides, by considering the uncertainty of hourly load/wind forecast, a scenario-based approach has been implemented such that the DEED problem would be studied in a stochastic environment referred to as stochastic DEED. In order to see the efficiency and feasibility of the proposed method, two standard test systems are employed as the case studies.
Numerical model of an Ar/NH3 atmospheric pressure direct current discharge in parallel plate geometry
Authors: Li Zhi , Zhao Zhen , Li Xuehui
Published: March 2012

A one dimensional fluid model is used to investigate the role of ammonia added to an argon DC discharge at atmospheric pressure. The equations solved are the particle balances, assuming a drift-diffusion approximation for the fluxes, and the electron energy balance equation. The self-consistent electric field is obtained from the simultaneous solution of Poisson’s equation. The electron-neutral collision rates are expressed as a function of the average electron energy. The model is comprised of 40 species (neutrals, radicals, ions, and electrons). In total, 75 electron-neutral, 43 electron-ion, 167 neutral-neutral, 129 ion-neutral, 28 ion-ion, and 90 3-body reactions are used in the model. The effects of gas mixing ratio on the densities of plasma species are systematically investigated. The calculated densities of the main plasma species are presented. It is found that in an Ar/NH3 plasma, the main neutrals (Ar*, Ar**, NH3*, NH, H2, NH2, H, and N2) are present at high densities. The Ar2+ and Ar+ ions are the dominant ions in the plasma. Furthermore, the NH3+ ions have a relatively higher density than other ammonia ions, whereas the density of other ions is negligible. Finally, a comparison is made between a pure Ar discharge and dielectric barrier discharge in a mixture of Ar/NH3. It is demonstrated that gas mixing ratio has a significant effect on the densities of plasma species, besides ammonia radical molecules and ammonia ions, and it also affects their ratio. Once the mixing ratio of Ar/NH3 is close to 1:1 at atmospheric pressure, the densities of NH, NH2+ and NH4+ reach to the maximum. The maximum of the different positive ammonia ions corresponds to the different ammonia mixing ratio.
Thickness driven stabilization of saw-tooth–like domains upon phase transitions in ferroelectric thin films with depletion charges
Authors: Misirlioglu I. B. , Cologlu H. N. , Yildiz M.
Published: March 2012

Ionized impurities have nearly always been neglected in discussing the limit of functionality of ferroelectric thin films. One would certainly expect that the thickness limit for functionality would be altered in the presence of ionized impurities, but how this would occur remains unclear. In this article, we analyze the domain structures as well as the phase transition temperatures in films with depletion charges for various film thicknesses. Depletion charges induce a position-dependent built-in field that leads to an inhomogeneous distribution of ferroelectric polarization. Such an inhomogeneity in the polarization results in strong depolarizing fields in films. We show that formation of saw-tooth–type domains is a way to circumvent the depolarizing fields, even in films with ideal electrodes. There is a critical film thickness above which the saw-tooth domains develop. On the other hand, the phase transition of the ultrathin structures with electrodes having a finite screening length, namely real electrodes, is always into the multidomain state during cooling from the paraelectric state, regardless of the presence of depletion charges. An important finding we have is that the transition temperature in films with real electrodes does not depend nearly at all on the depletion charge density unless it is very high (>1026 ionized impurities/m3). Relatively thick films (>8 nm in this work) with real electrodes that have very high depletion charge densities have transition temperatures very similar to those with the same charge density, but with ideal electrodes, making us conclude that thick films with high depletion charge densities will hardly feel the finite screening effects. The results are provided for (001) BaTiO3 films grown on (001) SrTiO3 substrates with pseudomorphic top and bottom metallic electrodes.
Weak turbulence in the magnetosphere: Formation of whistler wave cavity by nonlinear scattering
Authors: Crabtree C. , Rudakov L. , Ganguli G. , Mithaiwala M. , Galinsky V. , Shevchenko V.
Published: March 2012

We consider the weak turbulence of whistler waves in the in low-β inner magnetosphere of the earth. Whistler waves, originating in the ionosphere, propagate radially outward and can trigger nonlinear induced scattering by thermal electrons provided the wave energy density is large enough. Nonlinear scattering can substantially change the direction of the wave vector of whistler waves and hence the direction of energy flux with only a small change in the frequency. A portion of whistler waves return to the ionosphere with a smaller perpendicular wave vector resulting in diminished linear damping and enhanced ability to pitch-angle scatter trapped electrons. In addition, a portion of the scattered wave packets can be reflected near the ionosphere back into the magnetosphere. Through multiple nonlinear scatterings and ionospheric reflections a long-lived wave cavity containing turbulent whistler waves can be formed with the appropriate properties to efficiently pitch-angle scatter trapped electrons. The primary consequence on the earth’s radiation belts is to reduce the lifetime of the trapped electron population.
Determining the location and cause of unintentional quantum dots in a nanowire
Authors: Thorbeck Ted , Zimmerman Neil M.
Published: March 2012

We determine the locations of unintentional quantum dots (U-QDs) in a silicon nanowire with a precision of a few nanometers by comparing the capacitances to multiple gates with a capacitance simulation. Given that we observe U-QDs in the same location of the wire in multiple devices, their cause is likely to be an unintended consequence of the fabrication, rather than of random atomic-scale defects as is typically assumed. The locations of the U-QDs appear to be consistent with conduction band modulation from strain from the oxide and the gates. This allows us to suggest methods to reduce the frequency of U-QDs.
Long-term fluctuations in globally coupled phase oscillators with general coupling: Finite size effects
Authors: Nishikawa Isao , Tanaka Gouhei , Horita Takehiko , Aihara Kazuyuki
Published: March 2012

We investigate the diffusion coefficient of the time integral of the Kuramoto order parameter in globally coupled nonidentical phase oscillators. This coefficient represents the deviation of the time integral of the order parameter from its mean value on the sample average. In other words, this coefficient characterizes long-term fluctuations of the order parameter. For a system of N coupled oscillators, we introduce a statistical quantity D, which denotes the product of N and the diffusion coefficient. We study the scaling law of D with respect to the system size N. In other well-known models such as the Ising model, the scaling property of D is D∼O(1) for both coherent and incoherent regimes except for the transition point. In contrast, in the globally coupled phase oscillators, the scaling law of D is different for the coherent and incoherent regimes: D∼O(1/Na) with a certain constant a>0 in the coherent regime and D∼O(1) in the incoherent regime. We demonstrate that these scaling laws hold for several representative coupling schemes.
On the theoretical determination of the Prigogine-Defay ratio in glass transition
Authors: Tropin Timur V. , Schmelzer Jürn W. P. , Gutzow Ivan , Schick Christoph
Published: March 2012

In a recent analysis [J. W. P. Schmelzer and I. Gutzow, J. Chem. Phys. 125, 184511 (2006)10.1063/1.2374894] it was shown for the first time that – in contrast to earlier belief arising from the works of Prigogine and Defay [Chemical Thermodynamics (Longman, London, 1954), Chap. 19; The first French edition of this book was published in 1950] and Davies and Jones [Adv. Phys. 2, 370 (1953)10.1080/00018735300101252; Davies and Jones Proc. R. Soc. London, Ser. A 217, 26 (1953)10.1098/rspa.1953.0044] – a satisfactory theoretical interpretation of the experimentally observed values of the so-called Prigogine-Defay ratio Π, being a combination of jumps of thermodynamic coefficients at glass transition, can be given employing only one structural order parameter. According to this analysis, this ratio has to be, in full agreement with experimental findings, larger than one (Π > 1). Its particular value depends both on the thermodynamic properties of the system under consideration and on cooling and heating rates. Based on above-mentioned analysis, latter dependence on cooling rates has been studied in detail in another own preceding paper [T. V. Tropin, J. W. P. Schmelzer, and C. Schick, J. Non-Cryst. Solids 357, 1303 (2011)10.1016/j.jnoncrysol.2010.12.005]. In the present analysis, an alternative general method of determination of the Prigogine-Defay ratio is outlined, allowing one to determine this ratio having at ones disposal the generalized equation of state of the glass-forming melts under consideration and, in particular, the knowledge of the equilibrium properties of the melts in the glass transformation range. Employing, as an illustration of the method, a particular model for the description of glass-forming melts, theoretical estimates are given for this ratio being, again, in good agreement with experimental data.
Complementary metal-oxide-semiconductor-compatible and self-aligned catalyst formation for carbon nanotube synthesis and interconnect fabrication
Authors: Zhang Can , Yan Feng , Bayer Bernhard C. , Blume Raoul , van der Veen Marleen H. , Xie Rongsi , Zhong Guofang , Chen Bingan , Knop-Gericke Axel , Schlögl Robert , Capraro Bernard D. , Hofmann Stephan , Robertson John
Published: March 2012

We have for the first time developed a self-aligned metal catalyst formation process using fully CMOS (complementary metal-oxide-semiconductor) compatible materials and techniques, for the synthesis of aligned carbon nanotubes (CNTs). By employing an electrically conductive cobalt disilicide (CoSi2) layer as the starting material, a reactive ion etch (RIE) treatment and a hydrogen reduction step are used to transform the CoSi2 surface into cobalt (Co) nanoparticles that are active to catalyze aligned CNT growth. Ohmic contacts between the conductive substrate and the CNTs are obtained. The process developed in this study can be applied to form metal nanoparticles in regions that cannot be patterned using conventional catalyst deposition methods, for example at the bottom of deep holes or on vertical surfaces. This catalyst formation method is crucially important for the fabrication of vertical and horizontal interconnect devices based on CNTs.
Control of magnetic behavior by Pb1-xMnxS nanocrystals in a glass matrix
Authors: Dantas N. O. , Pelegrini F. , Novak M. A. , Morais P. C. , Marques G. E. , Silva R. S.
Published: March 2012

Diluted magnetic semiconductor nanocrystals, Pb1-xMnxS (x = 0.003, 0.005, and 0.010), of approximately 6 nm were successfully grown in a glass matrix by a combination of fusion and thermal annealing. X-ray diffraction measurements reveal that the as-produced nanocrystals (NC), of group IV–VI, are single-phase, nanosized and crystallized in the rock salt structure with replacement of Pb2+-ions by Mn2+-ions. Magnetic force microscopy images also confirmed the high quality of the Pb1-xMnxS NC samples, showing a uniform distribution of total magnetic moments in the nanocrystals. The observation of characteristic hyperfine structures from electron paramagnetic resonance measurements provided evidence for Mn2+ incorporation within the PbS dot structure. Moreover, low temperature magnetization and susceptibility data showed that most of the magnetic ions hosted by the nanocomposite samples are in a paramagnetic state.
Computer simulations of crystallization kinetics in amorphous silicon under pressure
Authors: Shanavas K. V. , Pandey K. K. , Garg Nandini , Sharma Surinder M.
Published: March 2012

With the help of computer simulations we have studied the crystallization kinetics of amorphous silicon in solid phase epitaxial (SPE) and random nucleation growth processes. Our simulations employing classical molecular dynamics and first principles methods suggest qualitatively similar behavior in both processes. Pressure is found to reduce the difference in molar volumes and coordination numbers between the amorphous and crystalline phases, which in turn lowers the energy barrier of crystallization. The activation energy for the SPE growth of four coordinated diamond phase is found to reach a minimum (a maximum in growth rates) close to 10 GPa when its density becomes equal to that of the amorphous phase. The crystallization temperatures of successive high pressure phases of silicon are found to decrease, offering a possible explanation for the pressure induced crystallization reported in this material.
Searching for high-k RE2O3 nanoparticles embedded in SiO2 glass matrix
Authors: Mukherjee S. , Lin Y. H. , Kao T. H. , Chou C. C. , Yang H. D.
Published: March 2012

Significant experimental effort has been explored to search and characterize high-k materials with magnetodielectric effect (MDE) of series of rare earth (RE) oxide (RE2O3) nanoparticles (NPs) embedded in SiO2 glass matrix by a sol-gel route. Properly annealed sol-gel glass (in which RE  =  Sm, Gd, and Er) shows colossal response of dielectric constant along with diffuse phase transition and MDE around room temperature. The radial distribution functions, reconstructed from extended x-ray absorption fine structure, show the shortening of RE3 + -O depending on the RE2O3 NP size, which is consistent with oxygen vacancy induced dielectric anomaly. The magnetoresistive MDE is very much conditioned by magnetic property of RE2O3 NP grain, the degree of deformation of the lattice and constituent host.
Feasibility, accuracy, and performance of contact block reduction method for multi-band simulations of ballistic quantum transport
Authors: Ryu Hoon , Park Hong-Hyun , Shin Mincheol , Vasileska Dragica , Klimeck Gerhard
Published: March 2012

Numerical utilities of the contact block reduction (CBR) method in evaluating the retarded Green’s function are discussed for 3D multi-band open systems that are represented by the atomic tight-binding (TB) and continuum k·p (KP) band model. It is shown that the methodology to approximate solutions of open systems, which has been already reported for the single-band effective mass model, cannot be directly used for atomic TB systems, since the use of a set of zinc blende crystal grids makes the inter-coupling matrix non-invertible. We derive and test an alternative with which the CBR method can be still practical in solving TB systems. This multi-band CBR method is validated by a proof of principles on small systems and also shown to work excellent with the KP approach. Further detailed analysis on the accuracy, speed, and scalability on high performance computing clusters is performed with respect to the reference results obtained by the state-of-the-art recursive Green’s function and wavefunction algorithm. This work shows that the CBR method could be particularly useful in calculating resonant tunneling features, but shows a limited practicality in simulating field effect transistors (FETs) when the system is described with the atomic TB model. Coupled to the KP model, however, the utility of the CBR method can be extended to simulations of nanowire FETs.
Cleaning graphene using atomic force microscope
Authors: Lindvall Niclas , Kalabukhov Alexey , Yurgens August
Published: March 2012

We mechanically clean graphene devices using an atomic force microscope (AFM). By scanning an AFM tip in contact mode in a broom-like way over the sample, resist residues are pushed away from the desired area. We obtain atomically flat graphene with a root mean square (rms) roughness as low as 0.12 nm after this procedure. The cleaning also results in a shift of the charge-neutrality point toward zero gate voltage, as well as an increase in charge carrier mobility.
Electronic structures in a CdSe spherical quantum dot in a magnetic field: Diagonalization method and variational method
Authors: Wu Shudong , Wan Li
Published: March 2012

The electronic structures of a CdSe spherical quantum dot in a magnetic field are obtained by using an exact diagonalization method and a variational method within the effective-mass approximation. The dependences of the energies and wave functions of electron states, exciton binding energy, exciton transition energy, and exciton diamagnetic shift on the applied magnetic field are investigated theoretically in detail. It is observed that the degeneracy of magnetic quantum number m is removed due to the Zeeman effect when the magnetic field is present. For the states with m ≥ 0, the electron energies increase as the magnetic field increases. However, for the states with m < 0, the electron energies decrease to a minimum, and then increase with increasing the magnetic field. The energies and wave functions of electron states obtained from the variational method based on the variational functions we proposed are in excellent agreement with the results obtained from the exact diagonalization method we presented. A comparison between the results obtained from the variational functions proposed by us and Xiao is also verified.
Channel length dependent sensitivity of Schottky contacted silicon nanowire field-effect transistor sensors
Authors: Shin Kyeong-Sik , Pan Andrew , On Chui Chi
Published: March 2012

In this paper, we examine the dependence of channel length on the sensitivity of Schottky contacted silicon nanowire field-effect transistor sensors. The fabricated experimental devices are used as photosensors as well as chemical sensors for pH sensing. The difference in light illuminated current response depends on the channel length in the linear regime. However, the current ratio (ΔILight-Dark/IDark) shows a different trend, being much improved for a longer channel in the subthreshold regime, which can be explained by the different subthreshold swings. Finally, devices of two different channel lengths are applied to detect the pH value of a solution yielding results similar to photosensing. From these results, we suggest that it is desirable to shorten the channel if the sensor is working in the linear region and increase the channel length if the sensor is used in the subthreshold region.
Threshold switching in Si-As-Te thin film for the selector device of crossbar resistive memory
Authors: Ho Lee Jong , Hwan Kim Gun , Bae Ahn Young , Woon Park Ji , Wook Ryu Seung , Seong Hwang Cheol , Joon Kim Hyeong
Published: March 2012

Threshold-switching (TS) and selector performances of Si-As-Te thin films for crossbar resistive memory were studied. Composition of the film was the major factor determining the emergence of TS. On-state conduction was found to occur at localized regions. The change of threshold voltage and off-state current by varying composition was observed, which were explained by the change in the concentration of defects and generation efficiency of carriers. The serially connected TiO2 unipolar switching memory and Si-As-Te threshold switch showed the resistance switching of the memory layer with the leakage current lowered by ∼120 times at 0.5 V.
Switching nonlinearity in a superconductor-enhanced metamaterial
Authors: Kurter Cihan , Tassin Philippe , Zhuravel Alexander P. , Zhang Lei , Koschny Thomas , Ustinov Alexey V. , Soukoulis Costas M. , Anlage Steven M.
Published: March 2012

We demonstrate a nonlinear metamaterial that can be switched between low and high transmission by controlling the power level of the incident beam. The origin of this nonlinear response is the superconducting Nb thin film employed in the metamaterial structure. We show that with moderate RF power of about 22 dBm it is possible to quench the superconducting state as a result of extremely strong current densities at the corners of the metamaterial’s split-ring resonators. We measure a transmission contrast of 10 dB and a change in group delay of 70 ns between the low and high power states.
Ratcheting of silicon island electrodes on substrate due to cyclic intercalation
Authors: Haftbaradaran Hamed , Gao Huajian
Published: March 2012

Analytical and numerical calculations are conducted to demonstrate a ratcheting mechanism of irreversible and accumulative deformation in patterned Si islands on substrates during lithiation/delithiation cycling. It is shown that ratcheting occurs as soon as one allows the yield stress of Si and/or the friction strength of the interface to vary from lithiation to delithiation half-cycles, and that this important failure mode can be avoided by simply reducing the lateral size of the islands below a critical length scale. The present study provides a feasible explanation for the experimentally observed ratcheting in fractured Si films on substrates.
The influence of the buffer layer architecture on transport properties for BaFe1.8Co0.2As2 films on technical substrates
Authors: Trommler S. , Hühne R. , Hänisch J. , Reich E. , Iida K. , Haindl S. , Matias V. , Schultz L. , Holzapfel B.
Published: March 2012

A low and almost temperature independent resistance in the normal state and an anomalous peak effect within the normal-superconducting transition have been observed in BaFe1.8Co0.2As2/Fe bilayers, prepared on ion beam assisted deposition-MgO/Y2O3 buffered technical substrates. A resistor network array sufficiently reproduces this effect, assuming an increase of the electrical conductance between tape and film with decreasing buffer layer thickness. Based on this model, we evaluated the influence of this effect on the critical current density and successfully reconstructed the superconducting transition of the bilayer.
Development of 10 kA high temperature superconducting power cable for railway systems
Authors: Tomita M. , Muralidhar M. , Suzuki K. , Fukumoto Y. , Ishihara A.
Published: March 2012

The superconducting Bi2Sr2Ca2Cu3Oy “Bi-2223” tapes made with a powder-in-tube process laminated with a copper alloy have been used to design and develop a 5 m long multilayer concentric cable to be applied in railway systems. The electrical performance of the conductor has been evaluated with DC transport current at an economical 77 K (liquid nitrogen temperature) in the self-field. The inner and outer sheet wires were able to sustain electric currents of 10 130 A and 10 910 A, respectively. These values are sufficient for several types of commercial applications. The current values are significantly higher than the earlier reported ones in Bi-2223 or YBa2Cu3Oy “Y-123” superconducting cables, indicating that the tape quality has considerably improved.
Epitaxial growth of Pb(Zr0.53Ti0.47)O3 films on Pt coated magnetostrictive amorphous metallic substrates toward next generation multiferroic heterostructures
Authors: Hu B. , Chen Y. , Yang A. , Gillette S. , Fitchorov T. , Geiler A. , Daigle A. , Su X. D. , Wang Z. , Viehland D. , Harris V. G
Published: March 2012

Piezoelectric films of Pb(Zr0.53Ti0.47)O3 (PZT) were deposited by pulsed laser deposition onto metallic magnetostrictive substrates. In order to optimize the growth of PZT films, a buffer layer of Pt was employed, as well as variation of deposition temperature, pressure, and laser energy. Room temperature θ-2θ x-ray diffraction measurements indicate all diffraction features correspond to reflections indexed to a single PZT phase of space group P4mm. Scanning electron microscopy images reveal pinhole-free dense films of pyramidal shaped crystal arrangements whose orientation and size were controlled by variation of oxygen pressures during deposition. The resulting PZT films had a value of d33 ∼ 46 pm/V representing a 53% increase over previous efforts to realize a piezoelectric/Metglas™ film heterostructure.