bluuebunny/crossref_metadata_2025 huggingface dataset:
Medizinische Check-ups auf dem Gesundheitsschiff. Nutzen für Risikogruppen oder Selbstelektion gesunder und gesundheitsbewusster Patienten?
Authors: Huber  , Bandi-Ott  , Käser  , Rosemann  , Senn
Published: December 2009

Das Gesundheitsschiff (GS) bietet im Rahmen einer Kreuzfahrt die Möglichkeit medizinischer Check-ups. Gesundheitszustand und -verhalten in den vorangegangenen 12 Monaten wurden bei den Teilnehmern mittels Fragebogen erfasst und im Querschnitt mit den Teilnehmern der repräsentativen Schweizerischen Gesundheitsbefragung (SGB) verglichen. Die Teilnahmequote betrug 74.6% (n = 206). Alkohol- und Tabakkonsum waren geringer und die Nutzung medizinischer (Vorsorge-)Leistungen (Anzahl Arztkontakte, Messung von Blutzucker und Cholesterin, Mammographien bei Frauen) waren häufiger bei der GS-Population im Vergleich zu Teilnehmern der SGB. Diese Unterschiede geben Hinweise, dass es sich bei den GS-Teilnehmern um eine positive Selbstselektion von Personen mit niedrigem Gesundheitsrisiko handelt. Ein zusätzlicher Gesundheitsnutzen durch medizinische Check-ups erscheint in diesem Rahmen daher zumindest fragwürdig.
Schmerzhafte Unterschenkelschwellung 52 Jahre nach Bimalleolarfraktur
Authors: Schneider  , Duewell  , Graf  , Forster
Published: December 2009

Die kalzifizierende Myonekrose ist eine seltene Spätkomplikation eines Logensyndroms und manifestiert sich am häufigsten am anterioren Kompartiment des Unterschenkels. Wir präsentieren den Fall eines 67-jährigen Rentners mit einem geschwollenen, druckdolenten und überwärmten linken Unterschenkel. Radiologisch zeigen sich charakteristische zirkuläre plaqueartige Verkalkungen. Sonographisch kommt auch eine Tendovaginitis der Sehne des M. tibialis anterior zur Darstellung. Ultraschallgesteuert kann daraus wenig Flüssigkeit aspiriert werden, in der sich Hydroxyapatitkristalle nachweisen lassen. Therapeutisch wird mit Erfolg ein kristallines Steroid infiltriert. Das Krankheitsbild wird anhand der Literatur diskutiert, in welcher sich 43 Fälle finden.
Biosphere‐atmosphere exchange of NOx in the tropical mangrove forest
Authors: Ganguly D. , Dey M. , Sen S. , Jana T. K.
Published: December 2009

Biosphere‐atmosphere exchange of NOx at the Sundarban mangrove forest along the northeast coast of the Bay of Bengal, India, showed uptake rates of −0.84 to −1.63 ng N m−2 s−1 during the day and both uptake and emission rates of −0.36 to 5.19 ng N m−2 s−1 during the night from September to February. However, during the period from March to August, NOx emission ranged between 0.34 and 2.13 ng N m−2 s−1 and 0.88 and 3.26 ng N m−2 s−1 in daytime and nighttime, respectively. During the postmonsoon period, NOx uptake could be attributed to mangrove stomatal activity during the day. Mangroves absorbed nitrogen from both the soil and the atmosphere. Seasonal and diurnal variability of NOx and O3 is partly due to plant growth in the postmonsoon period. In addition to the NOx‐O3 photochemical cycle, stomatal uptake of NOx could also be an important process for keeping a low‐ozone state at the land‐ocean boundary of the northeast coast of the Bay of Bengal.
Thermal ion flow in Saturn's inner magnetosphere measured by the Cassini plasma spectrometer: A signature of the Enceladus torus?
Authors: Wilson R. J. , Tokar R. L. , Henderson M. G.
Published: December 2009

For the middle and outer magnetosphere of Saturn (>5.5 RS), Cassini plasma spectrometer ion counting data provides thermal ion moments by assuming Maxwellian phase space density distributions for each ion species. However, in the inner magnetosphere (<5.5 RS) within Saturn's extended neutral cloud and proposed Enceladus torus, there is fresh ion production via charge exchange, yielding a complex ion velocity distribution. In this study, ion flow velocities in the inner region are obtained using the assumption that the ion phase space distributions are gyrotropic. Significantly sub‐corotating ion flow velocities (∼75% of corotation) are found in the vicinity of the Enceladus orbit and the radial extent of the sub‐corotation is about 1.0 RS, in reasonable agreement with the simulated radial dimension of the Enceladus torus.
Fundamental and higher‐mode Rayleigh wave characteristics of ambient seismic noise in New Zealand
Authors: Brooks Laura A. , Townend John , Gerstoft Peter , Bannister Stephen , Carter Lionel
Published: December 2009

In order to use ambient seismic noise for mapping Earth's structure, it is important to understand the spatio‐temporal characteristics of the noise field. This study uses data collected during four austral winter months of 2002 to investigate New Zealand's ambient seismic noise field in the double‐ocean‐wave‐frequency range (0.1–0.3 Hz). It is shown via beamforming analysis that there are two distinct dispersive waves in the data. These waves can be separated. Their estimated phase velocities (2.5–2 and 4–3 km/s in the frequency range 0.14–0.25 Hz) match well with fundamental and higher‐mode Rayleigh dispersion curves. Studies of double‐wave‐frequency microseisms elsewhere generally show the Rayleigh noise fields to be dominated by fundamental mode waves. The reason why higher‐mode signals are observed here may reflect a combination of long ocean wave periods, large waveheights, the direct deep water approach to narrow continental margins, and the proximity of the seismograph array to the source regions.
Internal tidal mixing as a control on continental margin ecosystems
Authors: Sharples Jonathan , Moore C. Mark , Hickman Anna E. , Holligan Patrick M. , Tweddle Jacqueline F. , Palmer Matthew R. , Simpson John H.
Published: December 2009

We show that a breaking internal tide at a shelf edge is a fundamental control on the structural and functional properties of ecosystems. Contrasts in vertical mixing of nitrate between the shelf and the open ocean correspond with horizontal and vertical changes in phytoplankton communities, with largest cells found in surface waters at the shelf edge. Intense fishing activity is commonly seen at continental shelf edges, targeting spawning fish stocks. We suggest that the internal tide, a globally ubiquitous physical process at steep shelf edge bathymetry, supports shelf edge fisheries by providing large‐celled phytoplankton for first‐feeding fish larvae. The repeatability of the internal tide removes fish from the need to time spawning with a spring bloom. Also, with large phytoplankton cells dominating particulate organic carbon export, the internal tides could be an important influence on spatial and temporal variability in patterns of global carbon sequestration in deep water and sediments.
Using satellite radar backscatter to predict above‐ground woody biomass: A consistent relationship across four different African landscapes
Authors: Mitchard E. T. A. , Saatchi S. S. , Woodhouse I. H. , Nangendo G. , Ribeiro N. S. , Williams M. , Ryan C. M. , Lewis S. L. , Feldpausch T. R. , Meir P.
Published: December 2009

Regional‐scale above‐ground biomass (AGB) estimates of tropical savannas and woodlands are highly uncertain, despite their global importance for ecosystems services and as carbon stores. In response, we collated field inventory data from 253 plots at four study sites in Cameroon, Uganda and Mozambique, and examined the relationships between field‐measured AGB and cross‐polarized radar backscatter values derived from ALOS PALSAR, an L‐band satellite sensor. The relationships were highly significant, similar among sites, and displayed high prediction accuracies up to 150 Mg ha−1 (±∼20%). AGB predictions for any given site obtained using equations derived from data from only the other three sites generated only small increases in error. The results suggest that a widely applicable general relationship exists between AGB and L‐band backscatter for lower‐biomass tropical woody vegetation. This relationship allows regional‐scale AGB estimation, required for example by planned REDD (Reducing Emissions from Deforestation and Degradation) schemes.
Plasma mass loading from the extended neutral gas torus of Enceladus as inferred from the observed plasma corotation lag
Authors: Pontius D. H. , Hill T. W.
Published: December 2009

At Saturn, significant plasma mass loading and radial transport occur together throughout the extended neutral torus, both producing corotation lags. We present a theory that depends upon the ratio of two classes of process: those injecting new mass (simple ionization) and those effectively removing momentum without changing plasma mass density (elastic ion‐neutral collisions, like‐species charge exchange). Both induce ionospheric torques, but only the former increases total outward mass flux. From an observed angular velocity, our model calculates the distribution of mass loading with radial distance. We present solutions based on Cassini Plasma Spectrometer measurements and theoretical chemistry models for Saturn's magnetosphere. We find a pronounced interaction peak near Enceladus' orbit and a broad ionization region between 5 and 8 Saturn radii (Rs). The total mass outflux at 8Rs is 100 kg/s × (Σ/0.1 S), where Σ is Saturn's ionospheric Pedersen conductance. The reported decrease in lag beyond 8Rs requires that Σ ≠ const or reducing the total mass outflux.
River‐induced particle distribution in the northwestern Black Sea (September 2002 and 2004)
Authors: Karageorgis A. P. , Kourafalou V. H. , Anagnostou C. , Tsiaras K. P. , Raitsos D. E. , Papadopoulos V. , Papadopoulos A.
Published: December 2009

Observations from two comprehensive oceanographic surveys on the northwestern Black Sea are analyzed to reveal the hydrological characteristics of the shelf area around the Danube delta in relation to particulate matter dynamics. These processes have broader implications on flows through the adjacent complex strait system. The surveys cover both a period of high (September 2002) and low (September 2004) discharge of the Danube River. The resulting low‐salinity waters generally occupied the upper 10–15 m within the 20–30 m thick warm layer that was separated by deeper cooler waters through a sharp thermocline. The buoyant plume was influenced by the discharge conditions and the prevailing wind patterns. The plume structure was identified using in situ bottle data, continuous beam transmission and fluorescence profiles, and satellite remotely sensed data. Particulate matter concentration values correlated with low‐salinity riverine waters and their maxima were recorded in the immediate vicinity of the Danube branches, decreasing rapidly toward the open sea. The preferred particle transport pathway in 2002 was along a narrow strip near the coast, with a south‐southwest direction, favored by the strong northeasterlies which predominated prior to the cruise. Low‐salinity waters and riverine particles in 2004 were characterized by mostly offshore removal, attributed to calmer northwesterlies prior to the survey. Changes in ambient stratification due to wind‐driven vertical displacements of the seasonal thermocline appeared to also influence the plume dynamics. The downwelling (upwelling) conditions that prevailed in 2002 (2004) were revealed in both the in situ vertical profile temperature measurements and the satellite‐derived sea surface temperature patterns.
Contribution of tropical cyclones to extreme rainfall events in the southeastern United States
Authors: Knight David B. , Davis Robert E.
Published: December 2009

Extreme precipitation has been increasing in the United States over the past century. In light of the associated impacts and possible linkages to climate change, this topic has garnered a great deal of attention from the scientific community and general public. Because tropical cyclones are a common source of heavy rainfall in the southeastern United States, we examined the contribution of tropical cyclone precipitation relative to overall extreme precipitation from all weather systems combined. We used a surface observation network over the period 1972–2007, consisting of first‐order and Cooperative Observer Program weather stations. Furthermore, to account for precipitation that may be unmeasured by rain gauges because of windy conditions during tropical cyclones, we employed a wind‐corrected data set and the North American Regional Reanalysis. According to several metrics of extreme precipitation, we found that extreme precipitation from tropical cyclones has been increasing over the past few decades. Additionally, the contribution of tropical cyclone precipitation to overall extreme precipitation has been significantly increasing by approximately 5%–10% per decade in the southeastern Atlantic coastal states. We attribute this rise in tropical cyclone contribution to an increase in both the storm wetness (precipitation per storm) and storm frequency over the period of record. There is little evidence that changes in storm duration are responsible for the increase. As such, we believe that an important factor in accurately projecting changes in extreme precipitation rests on whether tropical cyclone activity is driven more by natural decadal oscillations or by large‐scale warming of the environment.
Minimum variance analysis‐based propagation of the solar wind observations: Application to real‐time global magnetohydrodynamic simulations
Authors: Pulkkinen A. , Rastätter L.
Published: December 2009

The performance of the bulk of the current real‐time space weather applications is dependent on the accuracy of the driver solar wind data. One of the central aspects associated with the accuracy of the driver data is the determination of the propagation delay time of single‐spacecraft solar wind observations from Lagrangian point L1 to the Earth. In this work, the value of the minimum variance analysis‐based solar wind propagation technique as applied to real‐time global magnetohydrodynamic (MHD) simulations is investigated. Both the method that uses the newly introduced technique for minimizing the effect of the poorly determined phase planes and the minimum variance analysis‐based setup by Weimer and King (2008) along with the standard simple convection delay‐based (no phase planes used) solar wind propagation technique are applied to global MHD‐based modeling of the ground magnetic field and geomagnetically induced current variations. All computations are carried out in a real‐time setting. It is shown by means of comparisons to ground‐based observations that while the minimum variance analysis‐based propagation techniques can be used to optimize the timing associated with the propagated solar wind fluctuations, the improvement is so modest that from the statistical viewpoint, the benefit over using the simpler propagation technique vanishes for the studied storm period when the information is passed through real‐time global MHD modeling process.
Big science, little science
Authors: Petsko Gregory A.
Published: December 2009

Gregory Petsko explains why we should not be afraid to abandon some Big Science projects that suck up “outrageous levels” of financial support but deliver little in the way of results.
To be, or not to be?
Authors: Devolder Katrien
Published: December 2009

The recent generation of living mice from induced pluripotent stem cells presents a challenge to those who oppose the creation of human embryonic stem cell lines. Katrien Devolder explores the ethical issues.
Shaping the mitochondrion: mitochondrial biogenesis, dynamics and dysfunction
Authors: Shaw Janet M. , Winge Dennis R.
Published: December 2009

The regulation of mitochondrial fusion/fission, respiratory chain complex assembly, mitophagy and mitochondrial‐ER contact sites have profound implications for human disease, which are explored in this report.
Apoptosis: it's BAK to VDAC
Authors: Shore Gordon C.
Published: December 2009

VDAC's role in Bak‐dependent mitochondrial outer membrane permeabilization (MOMP) is controversial. Gordon Shore makes sense of it all in light of an EMBO reports paper that shows that VDAC mediates mitochondrial recruitment of Bak, thereby controlling tBid‐induced MOMP.
One lump or two?
Authors: Smallbone Kieran
Published: December 2009

We investigate methods for modelling metabolism within populations of cells. Typically one represents the interaction of a cloned population of cells with their environment as though it were one large cell. The question is as to whether any dynamics are lost by this assumption, and as to whether it might be more appropriate to instead model each cell individually. We show that it is sufficient to model at an intermediate level of granularity, representing the population as two interacting lumps of tissue.
Changes in the Tinnitus Handicap Questionnaire After Cochlear Implantation
Authors: Pan Tao , Tyler Richard S. , Ji Haihong , Coelho Claudia , Gehringer Anne K. , Gogel Stephanie A.
Published: December 2009

Purpose

To determine (a) changes in the Tinnitus Handicap Questionnaire (THQ) for patients using cochlear implants, (b) differences between patients who receive total or partial relief, and (c) identifiable characteristics of those who report tinnitus after implantation.

Method

Pre- and postoperatively, 244 adults were administered the THQ when they reported tinnitus.

Results

Of the 153 patients who had tinnitus preoperatively, 94 (61%) patients reported total suppression and 59 (39%) reported a partial reduction. In 91 patients who did not have tinnitus before implantation, 11 (12%) reported tinnitus postimplantation. The THQ score decreased from 41% preimplant to 30% postimplant. The largest reductions involved social handicap and hearing. Patients with a more severe hearing loss might be more likely to experience an exacerbation of their tinnitus. We were not able to clearly identify differences between patients who received total or partial relief and the characteristics of patients who reported tinnitus after implantation. Those who acquired tinnitus had the shortest duration hearing loss (5.6 years) and were the oldest (63 years). The average THQ score of patients getting tinnitus was 29%.

Conclusions

Most tinnitus patients benefit from receiving a cochlear implant.
Screening for Hearing Loss in the Elderly Using Distortion Product Otoacoustic Emissions, Pure Tones, and a Self-Assessment Tool
Authors: Jupiter Tina
Published: December 2009

Purpose

To determine whether distortion product otoacoustic emissions (DPOAEs) could be used as a hearing screening tool with elderly individuals living independently, and to compare the utility of different screening protocols: (a) 3 pure-tone screening protocols consisting of 30 dB HL at 1, 2, and 3 kHz; 40 dB HL at 1, 2, and 3 kHz; or 40 dB HL at 1 and 2 kHz; (b) the Hearing Handicap Inventory for the Elderly—Screening version (HHIE–S); (c) pure tones at 40 dB HL at 1 and 2 kHz plus the HHIE–S; and (d) DPOAEs.

Method

A total of 106 elderly individuals age 65–91 years were screened using the above protocols.

Results

Pass/fail results showed that most individuals failed at 30 dB HL, followed by DPOAEs, the 40-dB HL protocols, the HHIE–S alone, and the combined pure-tone/HHIE–S protocol. All screening results were associated except the HHIE–S and 30 dB HL and the HHIE–S and DPOAEs. A McNemar analysis revealed that the differences between the correlated pass/fail results were significant except for the HHIE–S and 40 dB at 1 and 2 kHz.

Conclusion

DPOAEs can be used to screen the elderly, with the advantage that individuals do not have to voluntarily respond to the test.
Modified Head Shake Computerized Dynamic Posturography
Authors: Honaker Julie A. , Converse Connie M. , Shepard Neil T.
Published: December 2009

Purpose

Recent research on head shake posturography has demonstrated a modest increase in sensitivity to identifying peripheral vestibular system asymmetry when horizontal head movements were added to portions of the standard Sensory Organization Test (SOT) battery. However, limitations with respect to the head shake protocol were outlined, and usable data for assessing performance could not be established. The purpose of this study was to test a change in protocol for use of head shake SOT to address the noted limitations.

Method

Forty participants ranging in age from 20 to 79 years with no history of dizziness completed Conditions 2 and 5 of the SOT portion of computerized dynamic posturography on EquiTest equipment, while maintaining head still as well as 4 horizontal head movement velocity tasks.

Results

Slope of a linear regression fit to 6 performance points was used to characterize each participant. Spearman’s ranked correlation (r) indicated a significant relationship between the slope of the line representing a decline in performance with age (r= −.52,p= .0006).

Conclusions

The head shake modification showed a trend in increasing the separation of normal individuals across age and eliminated the limitations addressed in earlier research. Future research will investigate the head shake modification for identifying vestibular peripheral system asymmetries.
Computational Neural Modeling of Speech Motor Control in Childhood Apraxia of Speech (CAS)
Authors: Terband Hayo , Maassen Ben , Guenther Frank H. , Brumberg Jonathan
Published: December 2009

Purpose

Childhood apraxia of speech (CAS) has been associated with a wide variety of diagnostic descriptions and has been shown to involve different symptoms during successive stages of development. In the present study, the authors attempted to associate the symptoms of CAS in a particular developmental stage with particular information-processing deficits by using computational modeling with the Directions Into Velocities of Articulators (DIVA) model. The hypothesis was that the speech production system in CAS suffers from poor feed-forward control and, consequently, an increased reliance on the feedback control subsystem.

Method

In a series of computer simulations, the authors systematically varied the ratio between feed-forward and feedback control during production attempts in the acquisition of feed-forward motor commands. The simulations were evaluated acoustically on 4 selected key symptoms of CAS.

Results

Results showed that increasing the reliance on feedback control causes increased severity of these 4 symptoms of CAS: deviant coarticulation, speech sound distortion, searching articulation, and increased variability.

Conclusions

The findings support the idea that the key symptoms found in CAS could result from an increased reliance on feedback control due to poor feed-forward commands. Two possible root causes of degraded feed-forward control in CAS are discussed: reduced somatosensory information and increased levels of neural noise.
The Acquisition of Auxiliary Syntax: A Longitudinal Elicitation Study. Part 1: Auxiliary BE
Authors: Theakston Anna L. , Rowland Caroline F.
Published: December 2009

Purpose

The question of how and when English-speaking children acquire auxiliaries is the subject of extensive debate. Some researchers posit the existence of innately given Universal Grammar principles to guide acquisition, although some aspects of the auxiliary system must be learned from the input. Others suggest that auxiliaries can be learned without Universal Grammar, citing evidence of piecemeal learning in their support. This study represents a unique attempt to trace the development of auxiliary syntax by using a longitudinal elicitation methodology.

Method

Twelve English-speaking children participated in 3 tasks designed to elicit auxiliary BE in declaratives and yes/no andwh-questions. They completed each task 6 times in total between the ages of 2;10 (years;months) and 3;6.

Results

The children’s levels of correct use of 2 forms of BE (is,are) differed according to auxiliary form and sentence structure, and these relations changed over development. An analysis of the children’s errors also revealed complex interactions between these factors.

Conclusion

These data are problematic for existing accounts of auxiliary acquisition and highlight the need for researchers working within both generativist and constructivist frameworks to develop more detailed theories of acquisition that directly predict the pattern of acquisition observed.
The Acquisition of Auxiliary Syntax: A Longitudinal Elicitation Study. Part 2: The Modals and Auxiliary DO
Authors: Rowland Caroline F. , Theakston Anna L.
Published: December 2009

Purpose

The study of auxiliary acquisition is central to work on language development and has attracted theoretical work from both nativist and constructivist approaches. This study is part of a 2-part companion set that represents a unique attempt to trace the development of auxiliary syntax by using a longitudinal elicitation methodology. The aim of the research described in this part is to track the development of modal auxiliaries and auxiliary DO in questions and declaratives to provide a more complete picture of the development of the auxiliary system in English-speaking children.

Method

Twelve English-speaking children participated in 2 tasks designed to elicit auxiliaries CAN, WILL, and DOES in declaratives and yes/no questions. They completed each task 6 times in total between the ages of 2;10 (years;months) and 3;6.

Results

The children’s levels of correct use of the target auxiliaries differed in complex ways according to auxiliary, polarity, and sentence structure, and these relations changed over development. An analysis of the children’s errors also revealed complex interactions between these factors.

Conclusions

These data cannot be explained in full by existing theories of auxiliary acquisition. Researchers working within both generativist and constructivist frameworks need to develop more detailed theories of acquisition that predict the pattern of acquisition observed.
Modeling Developmental Language Difficulties From School Entry Into Adulthood: Literacy, Mental Health, and Employment Outcomes
Authors: Law James , Rush Robert , Schoon Ingrid , Parsons Samantha
Published: December 2009

Purpose

Understanding the long-term outcomes of developmental language difficulties is key to knowing what significance to attach to them. To date, most prognostic studies have tended to be clinical rather than population-based, which necessarily affects the interpretation. This study sought to address this issue using data from a U.K. birth cohort of 17,196 children, following them from school entry to adulthood, examining literacy, mental health, and employment at 34 years of age. The study compared groups with specific language impairment (SLI), nonspecific language impairment (N-SLI), and typically developing language (TL).

Method

Secondary data analysis of the imputed 5-year and 34-year data was carried using multivariate logistic regressions.

Results

The results show strong associations for demographic and biological risk for both impairment groups. The associations are consistent for the N-SLI group but rather more mixed for the SLI group.

Conclusions

The data indicate that both SLI and N-SLI represent significant risk factors for all the outcomes identified. There is a strong case for the identification of these children and the development of appropriate interventions. The results are discussed in terms of the measures used and the implications for practice.
Louise Bourgeois, Ageing, and Maternal Bodies
Authors: Betterton Rosemary
Published: November 2009

This article explores late works by contemporary artist Louise Bourgeois that illuminate current concerns about ageing maternal bodies and the ambivalent responses of fear and loathing that they provoke. In 2003, Louise Bourgeois made an installation for the Freud Museum in Vienna entitled The Reticent Child, on the subject of her own earlier pregnancy and birth of her son, one of several works featuring maternity and fertility which Bourgeois has created in old age. In Nature Study 2007, made at the age of 96 years, she depicts carnal couples and pregnant and birthing figures embodied in brilliant pinks and scarlet reds. Bourgeois represents women as the powerful agents of the maternal function, marking a return to motherhood as a central topic of her earlier work. Edward Said posited sources of cultural meaning as ‘the whole notion of beginning, the moment of birth and origin … reproductive generation, maturity’, and ‘the last great problematic … the last and late period of life, the decay of the body’ ( Said, 2006 : 4–6). What does it mean for Bourgeois to return to the theme of birth in her nineties and how does it resonate with contemporary anxieties about the ageing maternal body? If the space of the gallery is a safe arena for a woman artist to present sexuality and maternity in old age, how are older women who break codes of fertility represented elsewhere? In a culture which is hostile to the conjunction of ageing women with motherhood, I shall argue that Bourgeois’ late maternal works can help to undo the taboo on older mothers.
Dendritic flux avalanches in superconducting films
Authors: Yurchenko V. V. , Johansen T. H. , Galperin Y. M.
Published: December 2009

Thermomagnetic instability in general, and dendritic flux avalanches in particular, have attracted considerable attention of both scientists and engineers working on superconductor applications. Though being harmful for the performance of many superconducting devices, the avalanches provide a fruitful playground for experimental and theoretical studies of complex dynamics of the vortex matter. In this paper we report on the progress in understanding the mechanisms responsible for the development of the giant magnetic avalanches. We review recent results on magneto-optical imaging of the fingering instability in superconducting films and analyze them on the basis of recent theoretical model that establishes criteria for onset of the dendritic avalanches.
Signal characteristics of charge-phase qubit detector with parametric energy conversion
Authors: Shnyrkov V. I. , Soroka A. A. , Krech W.
Published: December 2009

The characteristics of a partially coherent quantum detector based on a charge-phase qubit, coupled with a classical (ωT<kBT∕ħ) resonant circuit, are analyzed. It is shown that in an electromagnetic field signal characteristics with the maximum coefficient of conversion arise when the effective quantum inductance of the qubit assumes positive and negative values periodically with the frequency of low-frequency oscillations of the occupation probability of the energy levels (Rabi type) ΩR≈ωT. The physical nature of parametric energy conversion (regeneration) in a qubit detector with a periodic change of the sign of the effective inductance and its possible application in quantum informatics for detecting weak signals is discussed.
Nonstationary magnetization dynamics of point contacts with a single ferromagnetic film
Authors: Balkashin O. P. , Fisun V. V. , Yanson I. K. , Triputen’ L. Yu. , Konovalenko A. , Korenivski V.
Published: December 2009

The electric conductivity of point nanocontacts between 5, 10, and 100nm thick ferromagnetic (F) cobalt films and a nonmagnetic (N) metal (copper or silver) needle is investigated. Two fundamentally different mechanisms for the formation of the response signal to microwave irradiation have been observed for the first time. One mechanism is due to the effect of the rectification of high frequency ac current on the nonlinearity of the current-voltage characteristics due to the precession of the magnetization under the action of a constant transport current flowing through the contact. The second one is associated with the resonance excitation of the precession of the magnetization vector at the fundamental frequency and its harmonic by an external high-frequency field. The experimental results support a previous contention that a “surface spin valve” whose static and dynamic properties are similar to conventional F1–N–F2 spin valve [Nano Letters 7, 927 (2007)] is formed in the experimental F–N nanocontacts.
The role of the self-consistent equation in identifying the Andreev spectrum in a mesoscopic NS structure
Authors: Gogadze G. A. , Dolya S. N.
Published: December 2009

A self-consistent equation of differential form is obtained for a dimensionless magnetic flux in an NS structure, which is responsible for the magnetic moment jumps in the system.
The elastic constants and related properties of the epsilon polymorph of the energetic material CL-20 determined by Brillouin scattering
Authors: Haycraft James J.
Published: December 2009

The acoustic phonons of the epsilon polymorph of 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazatetracyclo [5.5.0.05,9.03,11] dodecane (ε-CL-20) have been studied using Brillouin scattering spectroscopy. Analysis of the acoustic phonon velocities allowed determination of the complete stiffness tensor for this energetic material. The results are compared to a theoretical determination of the ε-CL-20 elastic constants, bulk moduli, and shear moduli. The observed ordering of elastic constants, C22>C33>C11, is noted to be different from other nitramine energetic materials. Finally, the elasticity of ε-CL-20 is compared to recently published reports on cyclotrimethylene trinitramine’s (RDX) elasticity and the beta polymorph of cyclotetramethylene tetranitramine’s (β-HMX) elasticity.
Magnetization studies in IrMn/Co/Ru/NiFe spin valves with weak interlayer coupling
Authors: Alayo W. , Xing Y. T. , Baggio-Saitovitch E.
Published: December 2009

The magnetic interactions in the Ir20Mn80/Co/Ru/Py (Py=Ni81Fe19) spin valve structures have been studied by magnetization measurements. The Ru thickness was varied between 24 and 58 Å, and the thicknesses of the other layers were keep constant, resulting in multilayers with a strong exchange bias field (Heb) and weak oscillatory interlayer coupling. The bilinear and biquadratic coupling constants between Co and Py and the exchange anisotropy at the IrMn/Co interface were considered for modeling the magnetic hysteresis loops of the whole system. The interplay between these interactions gives rise to an increase (decrease) in the Heb value of the Co pinned layer for antiferromagnetic (ferromagnetic) interlayer coupling, if compared to the system with no interlayer coupling, and in a small exchange anisotropy field, proportional to the bilinear coupling energy, induced to the Py free layer.
Calculation of Cu/Ta interface electron transmission and effect on conductivity in nanoscale interconnect technology
Authors: Feldman Baruch , Dunham Scott T.
Published: December 2009

Resistivity augmentation in nanoscale metal interconnects is a performance limiting factor in integrated circuits. Here we present calculations of electron scattering and transmission at the interface between Cu interconnects and their barrier layers, in this case Ta. We also present a semiclassical model to predict the technological impact of this scattering and find that a barrier layer can significantly decrease conductivity, consistent with previously published measurements.
Magnetic-field-dependent optical transmission of nickel nanorod colloidal dispersions
Authors: Klein Tobias , Laptev Aleksej , Günther Annegret , Bender Philipp , Tschöpe A. , Birringer R.
Published: December 2009

Aqueous dispersions of nickel nanorods, ≈13 nm in diameter and 40–160 nm in length, were synthesized using ac electrodeposition into porous alumina templates. The nanorods in suspension can be aligned by modest magnetic fields, which leads to a change in the optical transmittance of the dispersion. Optical transmission measurements with polarized and unpolarized light as a function of magnetic field were performed on suspensions of different particle concentration and varying aspect ratio of the nanoparticles. The experimental results were compared with a theoretical model in which the optical absorption of the nanorods is calculated from the polarizability of prolate ellipsoids in the quasistatic approximation. The magnetic field dependence is introduced in terms of the static orientational distribution function of magnetic moments in an external field. In addition, the relaxation dynamics of the optical transmission was studied, which allowed us to determine the rotational diffusion coefficient of the nanorods in suspension.
Direct imaging of photoconductivity of solar cells by using a near-field scanning microwave microprobe
Authors: Hovsepyan Artur , Babajanyan Arsen , Sargsyan Tigran , Melikyan Harutyun , Kim Seungwan , Kim Jongchel , Lee Kiejin , Friedman Barry
Published: December 2009

A near-field scanning microwave microprobe (NSMM) technique has been used to investigate the photovoltaic effect in solar cells. As the photoconductivity of the n-type silicon layer in the solar cells was varied due to the incident light intensities and the wavelength, we could directly observe the photoconductivity changes inside the solar cells by measuring the change of reflection coefficient S11 of the NSMM at an operating frequency near 4.1 GHz. We also directly imaged the photoconductivity changes by NSMM. Photoconductivity in solar cells is determined from the visualized microwave reflection coefficient changes at the interfaces with high sensitivity.
Eu oxidation state in fluorozirconate-based glass ceramics
Authors: Henke B. , Paßlick C. , Keil P. , Johnson J. A. , Schweizer S.
Published: December 2009

The influence of InF3 doping and remelting on Eu-doped fluorozirconate-based glass ceramics was investigated using near-edge x-ray absorption and optical spectroscopy. It was found that the addition of InF3 to the melt decreases the Eu2+/Eu3+ mole ratio, while remelting leads to a significant change in the Eu2+/Eu3+ ratio in favor of Eu2+. Photoluminescence spectroscopy shows that additional annealing steps lead to the formation of BaCl2 nanoparticles in the glass. In as-made glass ceramics containing InF3, a phase transition of the nanoparticles from hexagonal to orthorhombic structure is observed. This phase transition is not observed in the remelted glasses studied here.
Tunneling escape time from a semiconductor quantum well in an electric field
Authors: Larkin I. A. , Ujevic Sebastian , Avrutin E. A.
Published: December 2009

We calculate the tunneling escape times of quasibound states in a quantum well under applied electric field. We refine the quasiclassical Wentzel–Kramers–Brillouin approximation for a multilayer heterostructure and find a simple analytical expression for the lifetime, which takes into account different effective masses and different dielectric constants inside the heterostructure layers. We compare the quasiclassical lifetime formula with exact numerical solutions of the (complex) Schrödinger equation. For the underbarrier action Sab≥ℏ/3, good agreement between the two approaches is demonstrated. Also, by analytical expansion of the Schrödinger equation we prove the quasiclassical formula for lifetime as an asymptotic limit of the exact solution.
Ab initio calculations on the borate nonlinear optical crystal BaAlBO3F2
Authors: Huang He , Lin Z. S. , Bai Lei , Hu Z. G. , Chen C. T.
Published: December 2009

BaAlBO 3 F 2 (BABF) crystal is a recently developed borate nonlinear optical crystal. However, re-examination has revealed a different space group from that previously measured. Since the newly and previously measured structures are very similar, their structural stabilities are compared by the plane-wave pseudopotential method, and the calculations confirm the correctness of the recent measurement. Furthermore, the electronic structures and the linear and nonlinear optical properties of BABF are theoretically studied. The calculated linear refractive indices and birefringence are in good agreement with the available experimental results, but the calculated second harmonic generation coefficient is much smaller than the experimental value, suggesting that this value should be remeasured. In order to elucidate the mechanism of the optical properties in BABF, a real-space atom-cutting technique is used to analyze the contributions of the respective ionic group. Finally, the comparison of optical effects for several crystals having the same structural characteristics of BABF is summarized, and the difference in the optical properties of these crystals is illuminated.
Extending the nanocluster-Si/erbium sensitization distance in Er-doped silicon nitride: The role of Er–Er energy migration
Authors: Kim In Yong , Shin Jung H. , Kim Kyung Joong
Published: December 2009

The nanocluster-Si (nc-Si)/Er3+ interaction distance in Er-doped silicon nitride is investigated using SiOx/Si3N4:Er/Si3N4/Si3N4:Er multilayers. The composition and thickness of SiOx layers were fixed to provide constant sensitization, while the thickness of Si3N4:Er layers was varied to probe distance-dependence of sensitization. We find that while the distance over which an nc-Si transfers energy to an Er3+ ion is constant at ∼0.3 nm, the effective sensitization distance over which an Er3+ is sensitized via nc-Si can be as large as ∼1.3 nm. Based on a widely used phenomenological model of the distance-dependent Er3+ photoluminescence intensity, we identify Er–Er energy migration as an important factor for the extension of the nc-Si sensitization distance over nc-Si energy transfer distance.
Dopant activation in ion implanted silicon by microwave annealing
Authors: Alford T. L. , Thompson D. C. , Mayer J. W. , Theodore N. David
Published: December 2009

Microwaves are used as a processing alternative for the electrical activation of ion implanted dopants and the repair of ion implant damage within silicon. Rutherford backscattering spectra demonstrate that microwave heating reduces the damage resulting from ion implantation of boron or arsenic into silicon. Cross-section transmission electron microscopy and selective area electron diffraction patterns demonstrate that the silicon lattice regains nearly all of its crystallinity after microwave processing of arsenic implanted silicon. Sheet resistance readings indicate the time required for boron or arsenic electrical activation within implanted silicon. Hall measurements demonstrate the extent of dopant activation after microwave heating of implanted silicon. Physical and electrical characterization determined that the mechanism of recrystallization in arsenic implanted silicon is solid phase epitaxial regrowth. The boron implanted silicon samples did not result in enough lattice damage to amorphize the silicon lattice and resulted in low boron activation during microwave annealing even though recrystallization of the Si lattice damage did take place. Despite low boron activation levels, the level of boron activation in this work was higher than that expected from traditional annealing techniques. The kinetics of microwave heating and its effects on implanted Si are also discussed.
Influence of adhesive rough surface contact on microswitches
Authors: Wu Ling , Rochus V. , Noels L. , Golinval J. C.
Published: December 2009

Stiction is a major failure mode in microelectromechanical systems (MEMS). Undesirable stiction, which results from contact between surfaces, threatens the reliability of MEMS severely as it breaks the actuation function of MEMS switches, for example. Although it may be possible to avoid stiction by increasing restoring forces using high spring constants, it follows that the actuation voltage has also to be increased significantly, which reduces the efficiency. In our research, an electrostatic-structural analysis is performed to estimate the proper design range of the equivalent spring constant, which is the main factor of restoring force in MEMS switches. The upper limit of equivalent spring constant is evaluated based on the initial gap width, the dielectric thickness, and the expected actuation voltage. The lower limit is assessed on the value of adhesive forces between the two contacting rough surfaces. The MEMS devices studied here are assumed to work in a dry environment. In these operating conditions only the van der Waals forces have to be considered for adhesion. A statistical model is used to simulate the rough surface, and the Maugis’s model is combined with Kim’s expansion to calculate adhesive forces. In the resulting model, the critical value of the spring stiffness depends on the material and surface properties, such as the elastic modulus, surface energy, and surface roughness. The aim of this research is to propose simple rules for design purposes.
Electron-hole pair mechanism for the magnetic field effect in organic light emitting diodes based on poly(paraphenylene vinylene)
Authors: Bagnich S. A. , Niedermeier U. , Melzer C. , Sarfert W. , von Seggern H.
Published: December 2009

We investigated the magnetic field effect (MFE) on current and electroluminescence in organic light emitting diodes based on poly(paraphenylene vinylene). The MFE was strictly positive in the full range of device operation and showed nonmonotonic dependencies on applied voltage and temperature. Furthermore, the MFE on current obtained in bipolar devices was significantly larger than in hole-dominated devices. We discuss our results in the framework of an electron-hole pair model and show that the model can explain all functional dependencies observed in our devices.
Buckling of defective carbon nanotubes
Authors: Zhang Y. Y. , Xiang Y. , Wang C. M.
Published: December 2009

Presented herein is an investigation into the buckling behavior of single-walled carbon nanotubes (SWCNTs) with defects via molecular dynamics (MD) simulations. Various kinds of defects including point defects (monovacancy, bivacancies, and line) and topological defect such as Stone–Wales (SW) are considered. The MD simulations performed on the SWCNTs are based on the reactive empirical bond-order and Lennard-Jones potentials for the bonded and nonbonded interactions, respectively. Different temperatures were considered to explore the thermal effect on the buckling behaviors of defective SWCNTs. It is observed that initial defects in the SWCNTs reduce their buckling capacities. The degree of reduction depends on the type of defects, chirality, and temperature. Point defects cause a greater reduction in buckling loads than SW defect. The degradation of the buckling resistance of carbon nanotubes is greater for zigzag CNTs at lower temperatures. It is also observed that reconstruction of defective SWCNTs can be realized either in a higher thermal environment or with a larger compressive force.
Study of ferro-antiferromagnetic transition in [001]-oriented L1 FePt1−xRhx film
Authors: Hasegawa T. , Miyahara J. , Narisawa T. , Ishio S. , Yamane H. , Kondo Y. , Ariake J. , Mitani S. , Sakuraba Y. , Takanashi K.
Published: December 2009

Magnetic properties of [001]-oriented L10 FePt1−xRhx films (tFePtRh=6.12 nm) with Rh composition (x) of 0≤x≤0.40 were studied, and the magnetic phase in a composition-temperature plane was investigated. At room temperature, the films with 0≤x≤0.32 were in a ferromagnetic (FM) phase with a coercivity of several kilo-oersteds, and the films with 0.34≤x≤0.40 were in an antiferromagnetic (AF) phase. At x=0.32, which is close to the critical composition of the FM-AF transition at room temperature, the uniaxial magnetocrystalline anisotropy (Ku) was about 1.7×107 erg/cm3. A bit patterning process using the discontinuous FM-AF transition was studied. First, microfabricated FePt square films (1.7 nm thick) were prepared on the AF FePt0.64Rh0.36 film (6.7 nm thick). Second, those square films and the FePt0.64Rh0.36 film were mixed by annealing. The Fe and Pt atoms were thermally diffused into the FePt0.64Rh0.36 film locally, and the composition of the diffused areas changed to FM FePt0.72Rh0.28. A magnetic force microscopy study suggested that only the diffused areas changed from AF to FM phase. A minimum FM dot size of 300×300 nm2 was realized, and the FM dots were multidomain structures.