bluuebunny/crossref_metadata_2025 huggingface dataset:
A Dome Shaped PVDF Loudspeaker Model
Authors: Gazengel B. , Hamery P. , Lotton P. , Ritty A.
Published: August 2011

An analytical model is developed that describes the behavior of a dome-shaped piezoelectric loudspeaker. The loudspeaker consists of a PVDF circular membrane coupled with a rear cylindrical cavity. The dome shape is obtained by means of a static differential pressure held between the
two faces of the membrane. The theoretical description of the transducer's behavior is conducted in two steps. In the first step, the static behavior of the membrane is studied in order to obtain the profile of the membrane when submitted to a static differential pressure. In the second step,
the dynamic behavior of the membrane is studied. Finally, the theoretical results obtained are compared with experiments in order to evaluate the accuracy of the model.
Time and Frequency Characteristics of Temporary Threshold Shifts Caused by Pure Tone Exposures
Authors: Ordoñez Rodrigo , Hammershøi Dorte
Published: August 2011

The time-frequency characteristics of Temporary Threshold Shifts (TTS) caused by pure tones were determined using the Békésy audiometric method with narrow-band noise of short duration as the probe stimuli. Two experiments were done using exposures of 3 min at 100 dB above
threshold. In the first experiment, the frequency dependent characteristics of TTS produced by a 500-Hz tone were assessed. Thresholds were determined from 0.25 to 2 kHz in 1/2-octave steps for up to 20 min after the exposure. The results showed that the maximum affected
frequency was 1/2 octave above the exposure frequency. In the second experiment, the TTS recovery curve produced by a 1-kHz pure tone exposure was assessed at 1.5 kHz, at approximately 15 s intervals for the first 5 min and at regularly increasing intervals up to 45 min after
the exposure. The results showed a maximum in the recovery around 2 min after the exposure. The data gathered in these experiments were used to construct a mathematical model of TTS recovery. The model describes both the 1/2-octave shift and the 2-min bounce and it can be
used in the comparison of temporary changes in the auditory function, assessed at different times and frequencies.
Perceptual Evaluation of Rolling Sound Synthesis
Authors: Murphy Emma , Lagrange Mathieu , Scavone Gary , Depalle Philippe , Guastavino Catherine
Published: August 2011

Three listening tests were conducted to perceptually evaluate different versions of a new real-time synthesis approach for sounds of sustained contact interactions. This study aims to identify the most effective algorithm to create a realistic sound for rolling objects. In Experiment
1 and 2, participants were asked to rate the extent to which 6 different versions sounded like rolling sounds. Subsequently, in Experiment 3, participants compared the 6 versions best rated in Experiment 1 and 2, to the original recordings. Results are presented in terms of both statistical
analysis of the most effective synthesis algorithm and qualitative user comments. On methodological grounds, the comparison of Experiments 1, 2 and 3 highlights major differences between judgments collected in reference to the original recordings as opposed to judgments based on memory representations
of rolling sounds.
Accessibility of Enzymatically DelignifiedBambusa bambosfor Efficient Hydrolysis at Minimum Cellulase Loading: An Optimization Study
Authors: Kuila Arindam , Mukhopadhyay Mainak , Tuli D. K. , Banerjee Rintu
Published: August 2011

In the present investigation,Bambusa bamboswas used for optimization of enzymatic pretreatment and saccharification. Maximum enzymatic delignification achieved was 84%, after 8 h of incubation time. Highest reducing sugar yield from enzyme-pretreatedBambusa bamboswas 818.01 mg/g dry substrate after 8 h of incubation time at a low cellulase loading (endoglucanase,β-glucosidase, exoglucanase, and xylanase were 1.63 IU/mL, 1.28 IU/mL, 0.08 IU/mL, and 47.93 IU/mL, respectively). Enzyme-treated substrate ofBambusa bamboswas characterized by analytical techniques such as Fourier transformed infrared spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscopy (SEM). The FTIR spectrum showed that the absorption peaks of several functional groups were decreased after enzymatic pretreatment. XRD analysis indicated that cellulose crystallinity of enzyme-treated samples was increased due to the removal of amorphous lignin and hemicelluloses. SEM image showed that surface structure ofBambusa bamboswas distorted after enzymatic pretreatment.
Simultaneous Determination of Amlodipine and Valsartan
Authors: Mohamed Nashwah Gadallah
Published: August 2011

A spectrophotometric method was developed for simultaneous determination of amlodipine (Aml) and valsartan (Val) without previous separation. In this method amlodipine in methanolic solution was determined using zero order UV spectrophotometry by measuring its absorbency at 360.5 nm without any interference from valsartan.

Valsartan spectrum in zero order is totally overlapped with that of amlodipine. First, second and third derivative could not resolve the overlapped peaks.

The first derivative of the ratio spectra technique was applied for the measurement of valsartan. The ratio spectrum was obtained by dividing the absorption spectrum of the mixture by that of amlodipine, so that the concentration of valsartan could be determined from the first derivative of the ratio spectrum at 290 nm. Quantification limits of amlodipine and valsartan were 10-80 μg/ml and 20-180 μg/ml respectively. The method was successfully applied for the quantitative determination of both drugs in bulk powder and pharmaceutical formulation.
Sharp Threshold of the Gross-Pitaevskii Equation with Trapped Dipolar Quantum Gases
Authors: Ma Li , Wang Jing
Published: August 2011

In this paper, we consider the Gross-Pitaevskii equation for the trapped dipolar quantum gases. We obtain the sharp criterion for the global existence and finite time blow-up in the unstable regime by constructing a variational problem and the so-called invariant manifold of the evolution flow.
Certain Properties of K0-monoids Preserved by Tracial Approximation
Authors: Fan Qingzhai
Published: August 2011

We show that the following K0-monoid properties of C*-algebras in the class are inherited by simple unital C*-algebras in the class TAΩ: (1) weak comparability, (2) strictly unperforated, (3) strictly cancellative.
Exploring the Meanings of Making Traditional Arts and Crafts among Older Women in Crete, Using Interpretative Phenomenological Analysis
Authors: Tzanidaki Despina , Reynolds Frances
Published: August 2011

Aim:

The aim of the study was to investigate the meanings of making traditional arts and crafts among older, retired women living in rural Crete, and the contribution of these occupations to wellbeing. Previous relevant research, conducted mainly in the United Kingdom and United States, had largely neglected the experiences of art-making in societies with strong cultural traditions of art-making.

Method:

Semi-structured interviews were conducted in Greek to collect qualitative accounts from 12 women aged over 65 years. The data were interpreted according to published guidelines for interpretative phenomenological analysis.

Findings:

The women identified various forms of art-making that were indigenous, such as weaving, lace-making and painting holy icons. They expressed deep respect for artistic traditions and took pride in preserving and teaching traditional skills and designs. They perceived art-making as promoting continuity of self, social status and spiritual wellbeing. Art-making was also used as a coping strategy for the challenges of later life, such as bereavement.

Conclusion:

Older women in Crete valued their involvement in traditional forms of art-making. These occupations enhanced wellbeing in several ways. Participants gained status, and a culturally recognised role in the community, from preserving and transmitting the skills required for indigenous forms of art and craft work.
Interrater Reliability of the Road Law and Road Craft Test as Part of the OT-DORA Battery for Off-Road Driver Assessment
Authors: Unsworth Carolyn A , Pallant Julie F , Russell Kay , Odell Morris , Coulson Melissa
Published: August 2011

Background:

The Occupational Therapy Driver Off Road Assessment (OT-DORA) Battery is in development as a comprehensive off-road evaluation of fitness to drive. Although several psychometric properties of the Road Law and Road Craft Test (RLRCT) have been previously studied, interrater reliability must also be established to include this test in the battery.

Aim:

The aim of the study was to determine the interrater reliability of the RLRCT.

Method:

Three occupational therapy driver assessors independently scored 20 client responses on the 14-item RLRCT.

Results:

The interrater reliability for all items, except item 6, was found to be between 0.57 and 1.00. The scoring instructions for item 6 were revised and the interrater reliability rose from 0.42 to 0.77.

Conclusion:

The RLRCT has been found to be reliable when administered by different raters and is thus suitable for inclusion in the OT-DORA Battery. Ongoing research to confirm the psychometric properties of the RLRCT is required.
The Effectiveness of Occupational Performance Outcome Measures within Mental Health Practice
Authors: Fuller Kate
Published: August 2011

Introduction:

The routine use of outcome measures is essential to the maintained delivery of quality care and the continued commissioning of mental health occupational therapy services. Occupational therapists are required to demonstrate that intervention is successful in an evidence-based, valid and reliable way. Therefore, this critical review aims to address the issue of choosing an appropriate occupational performance outcome measure for use within mental health services.

Method:

Evidence was critically appraised for the effectiveness of the Assessment of Communication and Interaction Skills (ACIS), Occupational Therapy Task Observation Scale (OTTOS), Canadian Occupational Performance Measure (COPM) and Goal Attainment Scaling (GAS), all recommended for use by occupational therapists within mental health practice.

Findings and discussion:

The review identifies that there are a limited number of clinically based studies evidencing the validity and reliability of occupational performance outcome measures. It also identifies a paucity of literature concerning service user experience of outcome measures, bringing into question how client centred and meaningful these tools are.
Study of the MLB parameterisation for change in surface solar irradiance with sun zenith angle in clear sky
Authors: Qu Z. , Blanc P. , Lefèvre M. , Wald L. , Oumbe A.
Published: August 2011

Abstract. The MLB parameterisation (Modified Lambert-Beer, Mueller et al., 2004) describes the change in SSI with sun zenith angle (SZA) in clear-sky conditions. It applies to the direct and global SSI as well as their spectral distribution. We assess its performances by comparing its results to the outputs of the radiative transfer model libRadtran and standard interpolation procedures. The standard two-point fitting MLB function performs very well at SZA between 0° and 60° and fairly bad from 60° to 89.9°. A parameterisation made of four MLBs for four intervals (0°, 60°), (60°, 75°), (75°, 85°) and (85°, 89.9°) is also tested. This piecewise MLB parameterisation exhibits satisfactory performances at any SZA and outperforms standard linear interpolation techniques. 95 % of errors in global SSI are less than 1 W m−2 for each band and less than 5 W m−2 for total irradiance.
Colonic Metastases from Pleomorphic Carcinoma of the Lung Presenting as an Ileocecal Intussusception
Authors: Rashid Sadat , Rajan Dhyan , Jacob Robin , Dahl Keith , Prasad Apsara , Singh Jaspreet , Siddiqui Ghulam , Sasthakonar Venkatesh , Freedman Lester , Gebre Wondwoosen , Takeshige Umeko , Subramani Krishnaiyer , Rizvon Kaleem , Mustacchia Paul
Published: August 2011

Pleomorphic carcinoma is a rare aggressive type of lung cancer that uncommonly metastasizes to the bowel, leading to bleeding, perforation, obstruction, and rarely intussusception. Serving as a lead point, metastatic lesions in the bowel may precipitate intussusception and require immediate surgical intervention. We present a rare case of colonic metastases from a primary lung malignancy, causing ileocecal intussusception in a 57-year old male.
Endometriosis and Ovarian Cancer: A Systematic Review
Authors: Sayasneh Ahmad , Tsivos Dimitris , Crawford Robin
Published: August 2011

Introduction. Endometriosis is one of the most common benign disorders which affects 10–15% of all women in reproductive age. The association between endometriosis and ovarian cancer has been frequently described in the medical literature. Purpose. To evaluate the literature for evidence of a correlation between endometriosis and ovarian cancer. Method. the English language literature (online MEDLINE and EMBASE database) was searched using the keywords endometriosis combined with cancer, tumour, tumor, carcinoma, or adenocarcinoma. All abstracts between January 1985 and August 2010 were reviewed. Full relevant articles were critically assessed. Reference lists of included studies were checked. Results. Seven out of the eight studies, included in our review, have shown an increased risk of ovarian cancer. However, the effect size is modest (OR, RR, and SIR) ranging between 1.32 and 1.9 (95% CI). A causative relationship between the two incidences cannot be confirmed. There is increasing evidence on the role of genetic mutations in ovarian clear-cell and endometrioid carcinoma developing from endometriosis. Conclusion. More evidence is needed before suggesting any change in the current management of endometriosis.
A Proof of Constructive Version of Brouwer's Fixed Point Theorem with Uniform Sequential Continuity
Authors: Tanaka Yasuhito
Published: August 2011

It is often said that Brouwer's fixed point theorem cannot be constructively proved. On the other hand, Sperner's lemma, which is used to
prove Brouwer's theorem, can be constructively proved. Some authors have presented a constructive (or an approximate) version of Brouwer's fixed point theorem using Sperner's lemma. They, however, assume uniform continuity of functions. We consider uniform sequential continuity of functions. In classical mathematics, uniform continuity and uniform sequential continuity are equivalent. In constructive mathematics a la Bishop, however, uniform sequential continuity is weaker than uniform continuity. We will prove a constructive version of Brouwer's fixed point theorem in an n-dimensional simplex for uniformly sequentially continuous functions. We follow the Bishop style constructive mathematics.
Embodying Emotional Disorders: New Hypotheses about Possible Emotional Consequences of Motor Disorders in Parkinson's Disease and Tourette's Syndrome
Authors: Mermillod Martial , Vermeulen Nicolas , Droit-Volet Sylvie , Jalenques Isabelle , Durif Franck , Niedenthal Paula
Published: August 2011

Parkinson's disease (PD) and Tourette's syndrome (TS) lead to important motor disorders among patients such as possible facial amimia in PD and tics in Tourette's syndrome. Under the grounded cognition framework that shows the importance of motor embodiment in emotional feeling (Niedenthal, 2007), both types of pathology with motor symptoms should be sufficient to induce potential impairments for these patients when recognizing emotional facial expressions (EFE). In this opinion paper, we describe a theoretical framework that assumes potential emotional disorders in Parkinson's disease and Tourette's syndrome based on motor disorders characterizing these two pathologies. We also review different methodological barriers in previous experimental designs that could enable the identification of emotional facial expressions despite emotional disorders in PD and TS.
Logistic Heat Integral Methods for the One-Phase Stefan Problem
Authors: Layeni O. P. , Adegoke A. M.
Published: August 2011

Logistic versions of the heat balance integral and refined integral methods are introduced. A benchmark with a one-phase Stefan problem under constant and time-dependent boundary conditions shows remarkable accuracy at estimating temperature distribution and position of the moving front.
Convergence Theorems for Finite Family of Multivalued Maps in Uniformly Convex Banach Spaces
Authors: Shehu Yekini
Published: August 2011

We introduce a new iterative process to approximate a common fixed point of a finite
family of multivalued maps in a uniformly convex real Banach space and establish strong convergence theorems
for the proposed process. Furthermore, strong convergence theorems for finite family of quasi-nonexpansive
multivalued maps are obtained. Our results extend important recent results.
Obesity, Visceral Fat, and NAFLD: Querying the Role of Adipokines in the Progression of Nonalcoholic Fatty Liver Disease
Authors: Mirza M. S.
Published: August 2011

Nonalcoholic fatty liver disease (NAFLD) represents a spectrum of clinicopathologic conditions ranging from steatosis alone to nonalcoholic steatohepatitis (NASH), with varying risks for progression to cirrhosis and hepatocellular carcinoma. There is mounting evidence that NAFLD not only complicates obesity, but also perpetuates its metabolic consequences. Critical event that leads to progressive liver injury in NAFLD is unknown. Obesity reflects a generalized proinflammatory state with its increased inflammatory markers like C reactive protein, IL-6, IL-8, IL-10, PAI-1, TNF-α, and hepatocyte growth factor. The elevated production of these adipokines is increasingly considered to be important in the development of diseases linked to obesity and the metabolic syndrome. Disordered cytokine production is likely to play a role in the pathogenesis of NAFLD. There is no effective treatment for NAFLD, though weight loss may halt disease progression and revert histological changes, the underlying mechanism remaining elusive. All stages of the disease pathway from prevention, early identification/diagnosis, and treatment require an understanding of the pathogenesis of liver injury in NAFLD.
A Comprehensive Study of Repetitive Transcranial Magnetic Stimulation in Parkinson's Disease
Authors: Kimura Hideki , Kurimura Masayuki , Kurokawa Katsurou , Nagaoka Utako , Arawaka Shigeki , Wada Manabu , Kawanami Toru , Kurita Keiji , Kato Takeo
Published: August 2011

The clinical benefits of repetitive transcranial magnetic stimulation (rTMS) for Parkinson's disease (PD) remain controversial. We performed a comprehensive study to examine whether rTMS is a safe and effective treatment for PD. Twelve PD patients received rTMS once a week. The crossover study design consisted of 4-week sham rTMS followed by 4-week real rTMS. The Unified Parkinson's Disease Rating Scale (UPDRS), Modified Hoehn and Yahr Stage, Schwab and England ADL Scale, Actigraph, Mini-Mental State Examination, Hamilton Depression Scale, Wechsler Adult Intelligence Scale-revised, and cerebral blood flow (CBF) and cerebrospinal fluid (CSF) examinations were used to evaluate the rTMS effects. Under both drug-on and drug-off conditions, the real rTMS improved the UPDRS scores significantly, while the sham rTMS did not. There were no significant changes in the results of the neuropsychological tests, CBF and CSF. rTMS seems to be a safe and effective therapeutic option for PD patients, especially in a wearing-off state.
The Polemics of the Quest for Liberty in the Poetry of George Gordon, Lord Byron
Authors: Veyu Ernest L. , Lum Mary-Louisa
Published: August 2011

The quest for liberty in Lord Byron’s poetry is a polemical issue because most critics have termed it nihilistic and satanic simply because the poet and his protagonists question Christian revelation and man-made laws. This article sets out to show that although Lord Byron and the Byronic hero as can be seen in the different poems do question Christian revelation and flout a number of generally accepted moral values, they do so in an attempt to find answers, which might help the individual to understand the universe, and be of help to the rest of mankind. The desire for liberty becomes the basic inspirational force, where conflict and warfare are justifiable pathways to the desired end. This paper also looks at the quest for liberty in Byron’s poetry from the perspective of the heroes’ ideals, justified by human nature and references to mythical rebels. Contrary to the generally accepted critical opinion that Lord Byron’s quest for liberty is essentially egocentric, this article seeks to show that the quest for liberty is the Byronic creed and the only constant element in the poet’s ambiguous life alongside the detestation of cant. The article argues that the Byronic hero’s deconstruction of philosophical and sociopolitical ideals does not result from the poetic persona’s lawlessness as generally assumed, but from an innate justifiable call for change, first for the individual and then for the common good. Related to his search for liberty, there are a lot of polemical issues around Byron’s notion of the ideal, which are partly addressed in this paper.
Linking past flood frequencies in Norway to regional atmospheric circulation anomalies
Authors: Støren Eivind N. , Kolstad Erik W. , Paasche Øyvind
Published: August 2011

Analysis of two continuous, high‐resolution palaeo‐flood records from southern Norway reveals that the frequency of extreme flood events has changed significantly during the Holocene. During the early and middle Holocene, flood frequency was low; by contrast, it was high over the last 2300 years when the mean flood frequency was about 2.5–3.0 per century. The present regional discharge regime is dominated by spring/summer snowmelt, and our results indicate that the changing flood frequency cannot be explained by local conditions associated with the respective catchments of the two lakes, but rather long‐term variations of solid winter precipitation and related snowmelt. Applying available instrumental winter precipitation data and associated sea‐level pressure re‐analysis data as a modern analogue, we document that atmospheric circulation anomalies, significantly different from the North Atlantic Oscillation (NAO), have some potential in explaining the variability of the two different palaeo‐flood records. Centennial‐scale patterns in shifting flood frequency might be indicative of shifts in atmospheric circulation and shed light on palaeo‐pressure variations in the North Atlantic region, in areas not influenced by the NAO. Major shifts are found at about 2300, 1200 and 200 years ago (cal. a BP). Copyright © 2011 John Wiley & Sons, Ltd.
Chronostratigraphy and lake-level changes of Laguna Cari-Laufquén, Río Negro, Argentina
Authors: Cartwright Alyson , Quade Jay , Stine Scott , Adams Kenneth D. , Broecker Wallace , Cheng Hai
Published: August 2011

Evidence from shoreline and deep-lake sediments show Laguna Cari-Laufquén, located at 41°S in central Argentina, rose and fell repeatedly during the late Quaternary. Our results show that a deep (> 38 m above modern lake level) lake persisted from no later than 28 ka to 19 ka, with the deepest lake phase from 27 to 22 ka. No evidence of highstands is found after 19 ka until the lake rose briefly in the last millennia to 12 m above the modern lake, before regressing to present levels. Laguna Cari-Laufquén broadly matches other regional records in showing last glacial maximum (LGM) highstands, but contrasts with sub-tropical lake records in South America where the hydrologic maximum occurred during deglaciation (17–10 ka). Our lake record from Cari-Laufquén mimics that of high-latitude records from the Northern Hemisphere. This points to a common cause for lake expansions, likely involving some combination of temperature depression and intensification of storminess in the westerlies belt of both hemispheres during the LGM.
Economics of integrated watershed management in the presence of a dam
Authors: Lee Yoon , Yoon Taeyeon , Shah Farhed A.
Published: August 2011

This paper presents an optimal control model of integrated watershed management in the presence of a dam. Management efforts focus on upstream soil conservation, reservoir‐level sediment removal, and downstream damage control from water pollution. Increased soil conservation potentially benefits farmers and also has the external benefit of reducing sediment accumulation in the reservoir. Sediment is released downstream of the reservoir using the hydrosuction sediment removal system (HSRS). This sediment release extends reservoir life and provides nutrients to downstream farmers who then use less fertilizer. Also included in the functions of the dam manager are the provision of water to downstream farms, the control of instream flow to mitigate downstream damages from water pollution, and the use of water treatment to meet quality standards for water supplied directly from the reservoir to residential users. An illustrative application of the model to Lake Aswan, located between Egypt and Sudan, indicates substantial benefits from far‐sighted behavior and cooperation across all agents. Moving from the baseline case that reflects the status quo to the socially optimal solution increases watershed net present value by more than $500 billion. Other scenarios with varying types of collaboration among the agents are also explored. Interestingly, while decisions with respect to soil conservation do impact the welfare of upstream farmers, the benefits to reservoir management and agriculture in Egypt are modest compared to benefits Egypt gets from improved control of instream flow. Also, subject to technical limits, increasing reservoir life through practice of HSRS is economically desirable.
Hunter-Gatherers in a Howling Wilderness: Farming economic systems for human needs
Authors: Wallace Rodrick
Published: August 2011

Recent advances in evolutionary theory applied to economic structure and process may permit construction of both new economic theory and new tools for data analysis that can help in the design of more robust economic policies and practices, resulting in less frequent and less disruptive Knightian transitions, and enabling as well the design of institutions that are, in turn, less disrupted by those that do occur.
Theoretical studies in the molecular Platonic solids: Pure and mixed carbon, nitrogen, phosphorus, and silicon tetrahedranes
Authors: Rayne Sierra , Forest Kaya
Published: August 2011

Calculations were conducted at the G4MP2 and G4 composite method levels of theory on the 35 potential carbon, nitrogen, silicon, and phosphorus tetrahedrane derivatives with the general form C~a~N~b~Si~c~P~d~H~(4-b-d)~ (where a+b+c+d=4). At both levels of theory, optimized electronic ground state neutral singlet gas phase (298.15 K, 1 atm) geometries were obtained for 24 of the 35 possible C/N/Si/P tetrahedrane derivatives. Corresponding enthalpies of formation were calculated using the atomization method. Triplet state neutral tetrahedron starting geometries for all compounds either resulted in cage opening or failed to converge. Only 9 cationic and 3 anionic forms converged to stable geometries that retained the tetrahedron cage and were absent imaginary frequencies, thereby allowing the calculation of adiabatic ionization energies and electron affinities.
Magnetodielectric response in 0.36BiScO3-0.64PbTiO3/La0.7Sr0.3MnO3 thin films and the corresponding model modifications
Authors: Zhang Shuai , Dong Xianlin , Gao Feng , Chen Ying , Cao Fei , Zhu Junyu , Tang Xiaodong , Wang Genshui
Published: August 2011

Dielectric relaxation and magnetodielectric (MD) effects were observed in 0.36BiScO3-0.64PbTiO3/La0.7Sr0.3MnO3 thin films. The universal dielectric response and distribution of relaxation time modifications were introduced into the Maxwell-Wagner (MW) model. Based on modified MW model, the negative MD response at low frequencies was attributed to magnetostriction of La0.7Sr0.3MnO3, while the large positive response at high frequencies mainly to the magnetoresistance of La0.7Sr0.3MnO3, and these two factors canceled each other out at intermediate frequencies. Moreover, a giant room temperature MD response of 9.5% was observed, and the linear MD response at 52 kHz was ascribed to the linear magnetoresistance effects.
Observations of Langmuir ponderomotive effects using the Solar TErrestrial RElations Observatory spacecraft as a density probe
Authors: Henri P. , Meyer-Vernet N. , Briand C. , Donato S.
Published: August 2011

Langmuir ponderomotive effects are nonlinear effects that enable to couple the electron and ion dynamics in space plasmas. The main difficulty to provide observational evidence of such nonlinear coupling is to simultaneously observe both fluctuations of plasma density and electric field. We have thus developed a new method to measure and to calibrate in situ small scale density fluctuations. Density fluctuations in the solar wind are measured using the observed quasistatic fluctuations of the STEREO spacecraft floating potential in the frequency range, where the spacecraft floating potential is in quasistatic equilibrium between photoionization and electron attachment, whereas the potential of the antenna, of much longer equilibrium time scale, is blind to the density fluctuations. Density fluctuations and Langmuir waves are thus directly and simultaneously measured using a dataset of more than three years of STEREO/WAVES measurements. We present here the first observational evidence for ponderomotive effects in the solar wind that nonlinearly couple density fluctuations to high energy Langmuir waves ((ε0E2)/(nkBT)>10-4).
Nanobubbles stability and multiwall carbon nanotubes straightening on few-layer graphene surfaces
Authors: Al-Harthi S. H. , Al-Barwani M. , Elzain M. , Al-Naamani N. , Hysen T.
Published: August 2011

The formation of nanobubbles, straightening, and orientation of multiwalled carbon nanotubes (MWCNTs) are investigated by preparing thin films employing dip casting of colloidal solutions on few-layer graphene (FLG) surfaces. In contrast to what is known, it is observed that nanobubbles are formed on an ultrathin dewetted layer of 0.5 nm thickness and exhibit unusual stability at ultrahigh vacuum conditions. Further, nanobubble rings are observed at atmospheric pressure. The results provide direct experimental evidence of the interaction between MWCNTs and nanobubbles at air–liquid–solid triple contact line and at lower step edge of the FLG, which together lead to the alignment of MWCNTs. Due to the balance between the surface tension forces and the strain forces arising from tube bending, MWCNTs attained straight rod-like shape. This enabled us to evaluate the elastic modulus of the MWCNT as E = 0.9 TPa.
Near-field: A finite-difference time-dependent method for simulation of electrodynamics on small scales
Authors: Coomar Arunima , Arntsen Christopher , Lopata Kenneth A. , Pistinner Shlomi , Neuhauser Daniel
Published: August 2011

We develop near-field (NF), a very efficient finite-difference time-dependent (FDTD) approach for simulating electromagnetic systems in the near-field regime. NF is essentially a time-dependent version of the quasistatic frequency-dependent Poisson algorithm. We assume that the electric field is longitudinal, and hence propagates only a set of time-dependent polarizations and currents. For near-field scales, the time step (dt) is much larger than in the usual Maxwell FDTD approach, as it is not related to the velocity of light; rather, it is determined by the rate of damping and plasma oscillations in the material, so dt = 2.5 a.u. was well converged in our simulations. The propagation in time is done via a leapfrog algorithm much like Yee's method, and only a single spatial convolution is needed per time step. In conjunction, we also develop a new and very accurate 8 and 9 Drude-oscillators fit to the permittivity of gold and silver, desired here because we use a large time step. We show that NF agrees with Mie-theory in the limit of small spheres and that it also accurately describes the evolution of the spectral shape as a function of the separation between two gold or silver spheres. The NF algorithm is especially efficient for systems with small scale dynamics and makes it very simple to introduce additional effects such as embedding.
Polymorphism of dense, hot oxygen
Authors: Goncharov Alexander F. , Subramanian N. , Ravindran T. R. , Somayazulu Maddury , Prakapenka Vitali B. , Hemley Russell J.
Published: August 2011

The phase diagram and polymorphism of oxygen at high pressures and temperatures are of great interest to condensed matter and earth science. X-ray diffraction and Raman spectroscopy of oxygen using laser and resistively heated diamond anvil cells reveal that the molecular high-pressure phase ɛ-O2, which consists of (O2)4 clusters, reversibly transforms in the pressure range of 44 to 90 GPa and temperatures near 1000 K to a new phase with higher symmetry. The data suggest that this new phase (η′) is isostructural to a phase η reported previously at lower pressures and temperatures, but differs from it in the P-T range of stability and type of intermolecular association. The melting curve increases monotonically up to the maximum pressures studied (∼60 GPa). The structure factor of the fluid measured as a function of pressure to 58 GPa shows continuous changes toward molecular dissociation.
Perturbations of eigenvalues embedded at threshold: Two-dimensional solvable models
Authors: Cacciapuoti Claudio , Carlone Raffaele , Figari Rodolfo
Published: August 2011

We consider a family of Hamiltonians describing a quantum particle interacting, via zero-range forces, with a localized spin in the plane. A sub-class of Hamiltonians shows eigenvalues and/or resonances at the threshold of the continuous spectrum and generates particle dynamics not affecting the localized spin. We examine the effect of a small particle-spin interaction on the spectral structure of such unperturbed Hamiltonians.
Electric field inside a “Rossky cavity” in uniformly polarized water
Authors: Martin Daniel R. , Friesen Allan D. , Matyushov Dmitry V.
Published: August 2011

Electric field produced inside a solute by a uniformly polarized liquid is strongly affected by dipolar polarization of the liquid at the interface. We show, by numerical simulations, that the electric “cavity” field inside a hydrated non-polar solute does not follow the predictions of standard Maxwell's electrostatics of dielectrics. Instead, the field inside the solute tends, with increasing solute size, to the limit predicted by the Lorentz virtual cavity. The standard paradigm fails because of its reliance on the surface charge density at the dielectric interface determined by the boundary conditions of the Maxwell dielectric. The interface of a polar liquid instead carries a preferential in-plane orientation of the surface dipoles thus producing virtually no surface charge. The resulting boundary conditions for electrostatic problems differ from the traditional recipes, affecting the microscopic and macroscopic fields based on them. We show that relatively small differences in cavity fields propagate into significant differences in the dielectric constant of an ideal mixture. The slope of the dielectric increment of the mixture versus the solute concentration depends strongly on which polarization scenario at the interface is realized. A much steeper slope found in the case of Lorentz interfacial polarization also implies a higher free energy penalty for polarizing such mixtures.
Zinc-oxide-based planar nanodiodes operating at 50 MHz
Authors: Irshaid Mustafa Y. , Balocco Claudio , Luo Yi , Bao Peng , Brox-Nilsen Christian , Song A. M.
Published: August 2011

Nanometer-scale self-switching devices (SSDs) fabricated in polycrystalline zinc oxide have been demonstrated up to at least 51.5 MHz, functioning as rectifiers to generate DC voltage. The SSDs require only a single nanolithography step and hence are of interest to low-cost printed electronics. The devices showed stable performance within the frequency range tested. The as-fabricated devices possessed strongly nonlinear current-voltage characteristics, resembling those of conventional diodes. After coating the devices with poly methyl methacrylate and poly vinylidene fluoride to enhance the electric field coupling, the nonlinear behavior was maintained while the device current increased dramatically.
First-principles generalized gradient approximation + U study of cubic CuAl2O4
Authors: Liu Qi-Jun , Liu Zheng-Tang
Published: August 2011

We have investigated the electronic, magnetic, mechanical, and optical properties in cubic CuAl2O4 by a first-principles ultrasoft pseudopotential of the plane-wave within the density-functional theory (DFT) plus the generalized gradient approximation (GGA) + U (Hubbard parameter) formalism. We find the polarized hole dz2 character induced the dz2 magnetic orbital ordering and the p-d hybridization results in the covalent bonding between Cu and O. The origins of electrons transitions in dielectric function are consistent with electronic structure aroused by crystal-field and Janhn-Teller effect.
Effect of pH on Cu(II) crystal growth onto the surface of chelating fiber
Authors: Gun Ko Young , Su Choi Ung
Published: August 2011

Herein, the effect of pH on Cu(II) crystal growth onto the surface of chelating fiber is presented. Poly(acryloamidino ethyleneamine) and poly(acryloamidino diethylenediamine) are synthesized as chelating polymers, and Cu(OH)2 crystal growth with the change of pH in an aqueous solution are observed using field-emission scanning electron microscopy. It is shown that the shapes of grown Cu(II) crystals on the chelating polymers depend on their alkyl amine numbers. The best fits of the isotherm data for Cu2+ adsorption and Cu(OH)2 crystal growth on the chelating polymers are obtained by means of our developed model.
A hybrid surface passivation on HgCdTe long wave infrared detector with in-situ CdTe deposition and high-density hydrogen plasma modification
Authors: Hu W. D. , Chen X. S. , Ye Z. H. , Lu W.
Published: August 2011

A hybrid surface passivation, in-situ CdTe passivation and high-density hydrogen plasma modification, is used to improve the surface quality of typical n+-on-p HgCdTe long wave infrared photodiode detectors. Three types of surface-passivated pixels, conventional, in-situ CdTe, and hybrid surface passivation, are fabricated in one chip for better comparison. The maximum dynamic resistances of the hybrid-surface-passivation device are increased to 1∼2 times greater than that in the conventional surface passivation technique. Theoretical modeling shows that the hybrid passivation can significantly suppress the trap-assisted tunneling current. Shallow traps close to the Fermi level under reverse voltage, which are the main source of the trap-assisted tunneling current for conventional surface passivation processing, are reduced by the hybrid passivation treatment.
Dense and uniform Au nanospheres on glass through confined nanosecond pulsed laser irradiation
Authors: Yang Yingling , Zhang Martin Y. , Cheng Gary J.
Published: August 2011

We utilize confined nanosecond pulsed laser irradiation to fabricate one monolayer of gold nanospheres on glass, with narrow size distribution and high packing densities. With a laser fluence of ∼400 mJ/cm2, the size of the nanospheres is as small as ∼50 nm and the packing density is as high as ∼2 × 1010 cm−2. The light heating efficiency is higher for smaller size nanospheres, so the heating and sphere regrowing process naturally results in the narrow size distribution for the gold nanospheres.
Scattering of Solitons from the Density Gradient of a Relativistic Bounded Plasma with Variable Streaming
Authors: Mukherjee J , Roy Chowdhury A
Published: August 2011

We study a relativistic bounded plasma consisting of hot ions and electrons with density gradient and variable streaming. It is observed that the nonlinear wave generated inside is governed by a variable coefficient KdV equation, which we analyse numerically. Furthermore, the solitary wave is scattered at the discontinuity due to inhomogeneity, and the characteristics of the left and right moving wave become different. Such scattering usually takes place in the solar wind, interplanetary shocks, and in the environment of a comet where, as the relativistic effect gives rise to streaming, the non-uniformity of the plasma leads to a density variation. By evaluating a suitable form lof such variations we compute the amplitude, velocity and width of the soliton before and after the scattering. The amplitude of the reflected wave is seen to decrease as in previous observations.
Tight-binding Calculation of Size Dependence of the Ionisation Potentials of Mercury Clusters
Authors: Zhao Jijun , Chen Xiaoshuang , Wang Guanghou
Published: August 2011

The gradual transition from van der Waals-like to metallic behaviour in mercury clusters is studied by a localised orbital theory based on the tight-binding approximation. The total density of states (DOS) of the Hg., clusters is obtained by means of the moment expansion method. The Fermi energy determined from the DOS is combined with the classical conducting sphere droplet (CSD) model to calculate the size-dependent ionisation potential (IP) of the cluster. The theoretical results are in good agreement with the experiments. The size dependence of the ionisation potential has an abrupt change at n = 13, indicating that the transition from insulating to metallic behaviour begins.
p-Wave Strength in the Low-energy 7Li(p,?0)8Be Cross Section
Authors: Barker FC
Published: August 2011

Recent fits to low-energy 7Li(p, "Yo)8Be angular distribution and analysing power data suggested a large p-wave strength. It is shown that acceptable fits to the data can be obtained by attributing the p-wave Ml contributions to the tails of the 17 �64 and 18 �15 MeV 1+ levels of 8Be, with p-wave strengths much less than those obtained previously, but only if some of the spectroscopic amplitudes have signs opposite to those suggested by shell model calculations and/or a fit to higher-energy data.
Novel fabrication technique for nanoscale hydrogen silsesquioxane structures using a direct printing technique
Authors: Yang Ki-Yeon , Oh Sang-Chul , Park Hyungwon , Lee Heon
Published: August 2011

Hydrogen silsesquioxane (HSQ), a type of spin-on glass, is an attractive material for nanobio, semiconductor and photoelectronic applications because it can be transformed into SiO2 by a simple annealing process. Studies on the fabrication of nanosized structures are necessary for the simple and easy production of HSQ nanostructures because of their unique characteristics. In this study, a fabrication method was developed for HSQ nanostructures as small as 50 nm using a direct printing technique with a poly (dimethylsiloxane) (PDMS) mold. Using this technique, HSQ nanostructures can be fabricated on a curved substrate
Monte Carlo‐based simulation of dynamic jaws tomotherapy
Authors: Sterpin E. , Chen Y. , Chen Q. , Lu W. , Mackie T. R. , Vynckier S.
Published: August 2011

Purpose

: Original TomoTherapy systems may involve a trade‐off between conformity and treatment speed, the user being limited to three slice widths (1.0, 2.5, and 5.0 cm). This could be overcome by allowing the jaws to define arbitrary fields, including very small slice widths (<1 cm), which are challenging for a beam model. The aim of this work was to incorporate the dynamic jaws feature into a Monte Carlo (MC) model called TomoPen, based on the MC codePENELOPE, previously validated for the original TomoTherapy system.

Methods:

To keep the general structure of TomoPen and its efficiency, the simulation strategy introduces several techniques: (1) weight modifiers to account for any jaw settings using only the 5 cm phase‐space file; (2) a simplified MC based model called FastStatic to compute the modifiers faster than pure MC; (3) actual simulation of dynamic jaws. Weight modifiers computed with both FastStatic and pure MC were compared. Dynamic jaws simulations were compared with the convolution/superposition (C/S) of TomoTherapy in the “cheese” phantom for a plan with two targets longitudinally separated by a gap of 3 cm. Optimization was performed in two modes: asymmetric jaws‐constant couch speed (“running start stop,” RSS) and symmetric jaws‐variable couch speed (“symmetric running start stop,” SRSS). Measurements with EDR2 films were also performed for RSS for the formal validation of TomoPen with dynamic jaws.

Results

: Weight modifiers computed with FastStatic were equivalent to pure MC within statistical uncertainties (0.5% for three standard deviations). Excellent agreement was achieved between TomoPen and C/S for both asymmetric jaw opening/constant couch speed and symmetric jaw opening/variable couch speed, with deviations well within 2%/2 mm. For RSS procedure, agreement between C/S and measurements was within 2%/2 mm for 95% of the points and 3%/3 mm for 98% of the points, where dose is greater than 30% of the prescription dose (gamma analysis). Dose profiles acquired in transverse and longitudinal directions through the center of the phantom were also compared with excellent agreement (2%/2 mm) between all modalities.

Conclusions:

The combination of weights modifiers and interpolation allowed implementing efficiently dynamic jaws and dynamic couch features into TomoPen at a minimal cost in terms of efficiency (simulation around 8 h on a single CPU).
Chemical components of the rhizomes of Drynaria fortunei (KUNZE) J. Sm. (polypodiaceae) in Vietnam
Authors: Trinh Pham Thi Nhat , Hao Nguyen Cong , Thao Phan Thanh , Dung Le Tien
Published: August 2011

From the ethanol extract of Drynaria fortunei (KUNZE) J. Sm., a new phenylpropanoid glycoside, fortunamide (1), was isolated and characterized by spectroscopic methods. Together with a new glycoside, 9 known compounds, including three curcuminoids (2–4), two isoprenylated flavonoids (5, 6), two flavonoids (7, 8), one monoterpenoid (9) and one phenolic acid (10) were isolated and identified by spectral data analysis from the rhizomes of Drynaria fortunei (KUNZE) J. Sm. Eight of them were isolated from Drynaria fortunei (KUNZE) J. Sm. for the first time.
SPECTRUM AND WAVE FUNCTIONS OF U(1)2+1 LATTICE GAUGE THEORY FROM MONTE CARLO HAMILTONIAN
Authors: HOSSEINIZADEH A. , KRÖGER H. , MELKONYAN G. , LAPRISE J. F. , MCBREEN M. , SCHEU N.
Published: August 2011

We address an old problem in lattice gauge theory — the computation of the spectrum and wave functions of excited states. Our method is based on the Hamiltonian formulation of lattice gauge theory. Using the method of Monte Carlo with importance sampling, we construct a stochastic basis of Bargmann link states, drawn from a physical probability density function. In the next step, we compute transition amplitudes between stochastic basis states. Then, we extract energy spectra and wave functions from a matrix of transition elements. To test this method, we apply it to U(1) lattice gauge theory in (2+1) dimensions and compute the energy spectrum, wave functions and thermodynamic functions of the electric Hamiltonian of this theory. We compare the numerical results with the analytical results and observe a reasonable scaling of energies and wave functions in the variable of time.
ANISOTROPIC UNIVERSE WITH ANISOTROPIC MATTER
Authors: LEE SUNGGEUN
Published: August 2011

We consider the effect of matter in the anisotropic universe of the scalar–tensor theory. We study Brans–Dicke model as a scalar–tensor theory. The matter is treated as perfect fluid type one. Just as the spacetime is anisotropic, the matter is also considered to be anisotropic. In order to give the present universe which is isotropic, the spacetime should be filled with the particular type of matter.