bluuebunny/crossref_metadata_2025 huggingface dataset:
A national review of cesarean delivery in Ethiopia
Authors: Fesseha Nebreed , Getachew Atnafu , Hiluf Mihret , Gebrehiwot Yirgu , Bailey Patricia
Published: August 2011

Objective

To describe Ethiopian national population‐based and institutional cesarean delivery rates by sector, and to describe indications for cesarean delivery, fetal and maternal outcomes, and aspects of quality of care.

Methods

The data source was the national baseline assessment of emergency obstetric and newborn care—a cross‐sectional, facility‐based survey of 797 facilities. Two instruments were used to collect the data for the present paper: a retrospective record review of 267 cesarean deliveries based on the last 3 performed in each facility; and a 12‐month summary of each facility's statistics on vaginal and abdominal deliveries.

Results

The national population‐based cesarean delivery rate was 0.6%, with regional rates varying from 0.2% to 9%. The overall institutional rate was 18%, which varied between 46% in the private for‐ profit sector and 15% in the public sector. Maternal indications accounted for 66% of the cesareans reviewed, and fetal indications for 34%. Three‐quarters of the cesareans were recorded as emergencies, but only 12% of these had their labor monitored with a partograph. The interval between decision and delivery was within 30 minutes for 36% of the women, 31–60 minutes for 23%, and more than 5 hours for 19%. Antibiotics were given in 94% of the reviewed cases; nevertheless, 12% of the cases reported wound infection. There were 2 maternal deaths and 14% of the newborns were stillbirths or died shortly after birth.

Conclusion

The study showed little progress in the proportion of all births delivered by cesarean and a high rate of cesarean among women attended in the private sector—indicating a need to monitor the appropriateness of obstetric care in all sectors and to increase access in rural areas. Clinical management protocols for obstetric and newborn care are needed, and audits of cesareans should be performed at all institutions, especially in the private sector. The importance of improving record keeping is crucial for informed local decision‐making.
Racial and Ethnic Disparities in Employment Outcomes for Persons With Traumatic Brain Injury: A Longitudinal Investigation 1‐5 Years After Injury
Authors: Arango‐Lasprilla Juan Carlos , Ketchum Jessica M. , Lewis Allen N. , Krch Denise , Gary Kelli W. , Dodd Brett Anthony
Published: August 2011

Objective

To determine whether differences exist in employment rates between whites, blacks, and Hispanics with traumatic brain injury (TBI) at 1, 2, or 5 years after injury; to determine whether changes occur in postinjury employment rates over time for whites, blacks, and Hispanics; and to determine whether changes in postinjury employment rates over time are different for whites, blacks, and Hispanics.

Setting

Sixteen TBI Model System centers.

Patients or Other Participants

Persons (3,940) with moderate‐to‐severe TBI who self‐reported as white, black, or Hispanic.

Main Outcome Measurements

Employment status dichotomized as competitively employed versus not competitively employed.

Results

The odds of competitive employment were significantly greater for whites versus blacks at 1, 2, and 5 years after injury and were greater for whites versus Hispanics at 1 and 2 years after injury; whites and Hispanics did not differ significantly at 5 years after injury; and blacks and Hispanics were not significantly different at 1, 2, or 5 years after injury. The odds of employment increased significantly from 1‐2, 2‐5, and 1‐5 years after injury for whites and Hispanics, whereas the odds of employment increased from 2‐5 and 1‐5 years after injury for blacks, with no significant difference between 1 and 2 years after injury for blacks. No evidence was found that the changes in employment rates over time were significantly different among the race and/or ethnicity groups.

Conclusion

Future researchers should seek to identify causative factors for employment disparities, and rehabilitation professionals should work to mitigate inequalities in employment among racial and ethnic groups with TBI.
Assessment of anthropogenic disturbance on soft-bottom macroinvertebrate assemblages across different spatial scales
Authors: Bedini Roberto , Batistini Francesca , Nannelli Annalisa , Piazzi Luigi
Published: August 2011

The present study aimed at evaluating the influence of different gradients of disturbance on the structure of soft-bottom macroinvertebrate assemblages. The following hypotheses were tested: (i) the structure of benthic assemblages does not differ along a gradient of distance from a point-source of pollution; and (ii) this pattern was not influenced by the level of anthropogenic pressure that characterized the area. A combination of multivariate and univariate techniques was used to detect differences in the structure of assemblages among three areas characterized by different environmental conditions, among three distances from point sources of pollution within each area and in two different periods within one year. Differences among conditions in the structure of macroinvertebrate assemblages were evident independently from temporal changes. However, patterns of variability along gradients of disturbance were influenced by the environmental conditions of the studied areas. The total richness was similar in the three studied areas, while beta diversity showed patterns related to both area and distance from point sources of pollution. The results also underlined the suitability of multivariate analysis of the whole community to detect environmental changes.
Sallow-skin horseshoe crabs (late juvenile Tachypleus tridentatus) as osmoconformers
Authors: Liao Yongyan , Chen Chang-Po , Hsieh Hwey-Lian , Cao Yucheng , Chen Jiejun
Published: August 2011

Sallow-skin horseshoe crabs (late juvenile Tachypleus tridentatus) from 30‰ salinity seawater were subjected to salinities ranging from 0‰ to 70‰ at 5‰ intervals for 7 days. They were returned to 30‰ salinity for 3 days for recovery. During this period, the survival rate, feeding rate, and body mass of the horseshoe crabs were measured. The sallow-skin horseshoe crabs survived well at 15‰–60‰ salinity, fed well at 30‰–55‰ salinity, gained mass at 0‰–25‰ salinity, lost mass at 45‰–70‰ salinity, and maintained mass at 30‰–40‰ salinity during salinity challenge. During the recovery period, the dehydrated (mass lost) horseshoe crabs rapidly gained mass, whereas the water-retaining (mass gained) horseshoe crabs rapidly lost mass. These results indicate that the sallow-skin T. tridentatus horseshoe crabs are osmoconformers and can tolerate a wide range of salinity changes, adapting gradually from inshore low salinity to offshore high salinity.
Ethnic Configuration and State-Making: A Fujian Case
Authors: KE FAN
Published: August 2011

This paper examines the relationship between ethnic configuration and state social policy in a Chinese context. Why did the Chinese communist government have to implement a preferential policy towards ethnic minorities, and to what extent has this policy come to reshape peoples’ consciousness of their group membership? As well as analysing the reasons and intents of the Chinese Communist Party when dealing with the minority issue before and after it attained power, this paper argues that categorizing of the population served to establish the state apparatus. Why the project of ethnic identification was first initiated in Fujian (a province best known for its overwhelming Han culture) is also discussed. By unfolding the process of searching for ethnic representation in Fujian in the early 1950s, this paper further argues that the major concern of the party-state regarding ethnic minorities is to hold onto its power. Finally, this paper documents how government agents, when investigating ethnicity, interacted with the local population. The Fujian case implies as well as exemplifies how ethnicity can be invented, constructed or reconstructed as a particular representation in relation to state formation.
PID and inverse-model-based control of a twin rotor system
Authors: Toha S. F. , Tokhi M. O.
Published: August 2011

The use of active control techniques has intensified in various control applications, particularly in the field of aircraft systems. This paper presents an investigation into the control of rigid-body and flexible motion of a twin rotor multi-input multi-output system (TRMS) using intelligent inverse-model-based control schemes. The TRMS is an aerodynamic test rig representing the control challenges of modern air vehicle. The augmented feedback PID and feedforward inverse-model-based control has led to good tracking response and vibration reduction of the TRMS, with the use of particle swarm optimisation (PSO). As a comparison, methods using PID controllers are also presented. Experimental results are obtained using the test rig, confirming the viability and effectiveness of the proposed methodology as opposed to conventional PID controllers. The results and evidence from this method are justified, presented and discussed.
Heuristic control of bipedal running: steady-state and accelerated
Authors: Perkins A. D. , Waldron K. J. , Csonka P. J.
Published: August 2011

The design, control, and actuation of legged robots that walk is well established, but there remain unsolved problems for legged robots that run. In this work, dynamic principles are used to develop a set of heuristics for controlling bipedal running and acceleration. These heuristics are then converted into control laws for two very different bipedal systems: one with a high-inertia torso and prismatic knees and one with a low-inertia torso, articulated knees, and mechanical coupling between the knee and ankle joints. These control laws are implemented in simulation to achieve stable steady-state running, accelerating, and decelerating. Stable steady-state running is also achieved in a planar experimental system with a semiconstrained torso.
FromBogeymantoBison: A Herd-Like Amnesia of HIV/AIDS in Theatre?
Authors: CAMPBELL ALYSON
Published: August 2011

Queer theorists from across a broad range of disciplines argue that we are in a ‘normalizing’ or ‘homonormative’ period, in which marginalized subjectivities strive to align themselves with hegemonic norms. In terms of LGBTQ rights and representation, it can be argued that this has resulted in an increased visibility of ‘desirable’ gays (monogamous – ideally civil-partnered, white, financially independent, able-bodied) and the decreased visibility of ‘undesirable’ gays (the sick, the poor, the non-white, the non-gender-conforming). Focusing specifically on the effects of this hierarchy on the contemporary theatrical representation of gay HIV/AIDS subjectivities, this article looks at two performances, Reza Abdoh'sBogeyman(1991) and Lachlan Philpott'sBison(2009–10). The article argues that HIV/AIDS performance is as urgently necessary today as in the early 1990s, and that a queer dramaturgy, unafraid to resist the lure of normativity or the ‘gaystreaming’ of LGBT representation, is a vital intervention strategy in contemporary (LGBT) theatre.
Synge Scholarship: Nothing to Do with Nationalism?
Authors: COLLINS CHRISTOPHER
Published: August 2011

John Millington Synge (1871–1909) is the fulcrum upon which Irish drama and theatre studies is balanced. Synge's nodal position is predicated upon the dramatist's rock ‘n’ roll recalcitrance towards the dramaturgical praxis of his contemporaries; his subject matter was as shocking as the Anglo-Irish idiom in which it was articulated. After Synge's premature death in 1909, W. B. Yeats's fundamental concern was that Synge scholars would attempt ‘to mould . . . some simple image of the man’. However, W. J. McCormack's concentric biography of Synge, The Fool of the Family: A Life of J. M. Synge, and Ann Saddlemyer's The Collected Letters of John Millington Synge, have demonstrated that Synge's life was complex, multifaceted and in deep dialogue with Irish culture. But with respect to Synge's drama a simple image has surrounded critical discourse: the politics of Irish nationalism.
A large outbreak of scombroid fish poisoning associated with eating yellowfin tuna (Thunnus albacares) at a military mass catering in Dakar, Senegal
Authors: DEMONCHEAUX J.-P. , MICHEL R. , MAZENOT C. , DUFLOS G. , IACINI C. , DELAVAL F. , SAWARE E. M. , RENARD J.-C.
Published: August 2011

On 26 November 2010, an outbreak of scombroid fish poisoning occurred in the French Armed Forces in Dakar, Senegal. This chemical intoxication, due to high histamine concentration in fish, is often mistaken for an allergic reaction. A case-control study was undertaken including the 71 cases and 78 randomly selected controls among lunch attendees. The usual symptoms for scombroid fish poisoning were observed in cases, i.e. flushing (85·9%), headache (83·1%), rapid/weak pulse (59·1%) and diarrhoea (47·9%). Symptoms occurred from within a few minutes to up to 3 h following the meal. Most patients quickly recovered with antihistamine and/or symptomatic treatment. Tuna was the only food item positively associated with illness (odds ratio 36·3, 95% confidence interval 6·3–210·0), with the risk of illness increasing with the quantity of fish consumed. No bacterial contamination was found in leftover food, but histamine concentration in tuna was found to be 4900 mg/kg, almost 50-fold higher than the concentration allowed by European regulations. This report is unique because of the large size of the case series – to our knowledge, the largest event of scombroid fish poisoning ever reported – and the chemical and bacteriological analyses results obtained on leftover food.
Seed dormancy and germination inVitis amurensisand its variation
Authors: Wang W.Q. , Song S.Q. , Li S.H. , Gan Y.Y. , Wu J.H. , Cheng H.Y.
Published: August 2011

There is little information about seed dormancy release and germination behaviour inVitis amurensis, which is one of the most important wildVitisspecies. This work aimed to investigate the dormancy release and germination characteristics and their variation inV. amurensisseed. Seed dormancy was released by: (1) stratification at 5, 10, 15, 20, 25 and 15/5°C, respectively; (2) stratification at 25°C followed by stratification at 5°C; (3) 5°C stratification before or after seed drying; and (4) stratification at a series of relative humidities (RHs) at 5 and 25°C. The freshly harvested and dormancy-released seeds were germinated at three fluctuating and four constant temperatures. InV. amurensis: (1) dormancy release could occur at temperature ≤ 25°C, but was maximal at 5°C for all varieties; (2) dormancy release and induction occurred simultaneously during stratification; (3) the rates of dormancy release and induction were dependent on temperature; (4) seed moisture content affected dormancy release with a temperature-dependent pattern; (5) seeds germinated better at fluctuating temperature than at constant temperature. However, the optimum condition for stratification and germination, the rates of dormancy release and induction, and the response of seeds to warm stratification, to drying and to germination temperature varied significantly among theV. amurensisvarieties. Our data imply that seed dormancy and germination inV. amurensisnot only have intra-species similarity, but also vary within species, which may be due to differences in environmental conditions at the original growth and cultivated sites.
Wirksamkeit von schulbasierten Gruppeninterventionen zur Depressionsprävention
Authors: Passon Anna Marie , Gerber Andreas , Schröer-Günther Milly
Published: August 2011

Fünf bis zehn Prozent aller Kinder und Jugendlichen in Deutschland leiden an depressiven Symptomen. Chronische Depressionen gehen regelmäßig mit ersten Erkrankungssymptomen im Kindes- und Jugendalter einher. Der frühen Prävention depressiver Störungen kommt folglich eine hohe Bedeutung zu. Wir untersuchten die Wirksamkeit nichtpharmakologischer schulbasierter Gruppeninterventionen zur Depressionsprävention anhand eines systematischen Literaturreviews. Signifikante Verbesserungen depressiver Störungen konnten in 61 Prozent der eingeschlossenen Studien festgestellt werden. Aufgrund der Heterogenität von Studiendurchführung und –design können keine eindeutigen Aussagen abgeleitet werden, welche Faktoren zu einem Erfolg oder Misserfolg der Programme beitragen. Eine flächendeckende Umsetzung erscheint aufgrund der offenen Fragen zur optimalen Ausgestaltung verfrüht.
Wissens- und Einstellungsänderungen zu Depression im Jugendalter
Authors: Allgaier Antje-Kathrin , Schiller Yvonne , Schulte-Körne Gerd
Published: August 2011

Es bestehen nach wie vor Wissenslücken und Stigmata bei Jugendlichen bezüglich Depression und Suizidalität. Erste internationale Initiativen für Jugendliche zeigen, dass bereits niederschwellige Maßnahmen zu einer signifikanten Wissenszunahme und Einstellungsänderung führen können. Evaluationsstudien zu depressionsspezifischen Aufklärungsmaterialien im Jugendalter fehlen jedoch bislang. Um diese Lücke zu schließen, wurde eine Aufklärungsbroschüre zu Depression für Jugendliche mit dem Ziel entwickelt, spezifisches Wissen zu vermitteln und Vorurteile abzubauen. An einer Stichprobe von 156 Schülern der neunten Jahrgangsstufe wurde die Broschüre in einer Prä-Post-Erhebung evaluiert. Nach Korrektur für multiples Testen zeigten sich für 32 der 50 Fragebogenitems signifikante Veränderungen bezüglich Wissen und Einstellungen. Besonders deutliche Effekte wurden in den Kategorien „Symptome“ und „Antidepressiva“ erreicht. Die größten Verbesserungen wiesen Gymnasiasten auf, gefolgt von Real- und Hauptschülern. Die Akzeptanz der Aufklärungsbroschüre wurde anhand der Kategorien „Gestaltung“, „Inhalt“ und „Nutzen“ erfasst. Die Jugendlichen beurteilten die Broschüre in allen Kategorien positiv und vergaben als Gesamtbewertung die Schulnote „gut“.
Methodological and Epistemological Issues Raised by the Use of the Rorschach Comprehensive System in Cross-Cultural Research
Authors: Franchi Vijé , Andronikof-Sanglade Anne
Published: August 2011

L’intérêt du Rorschach en Système Intégré pour la recherche interculturelle réside dans la possibilité qu’il offre de (a)accéder à des aspects de la structure du psychisme et du fonctionnement psychologique que des approches conventionnelles ne peuvent atteindre; (b)fournir une clé pour comprendre les données obtenues par d’autres techniques en situant ces données dans le contexte de la culture, de l’histoire personnelle et du fonctionnement psychologique global de l’individu.

Outre sa pertinence pour la recherche, le Rorschach fournit une description étendue du monde de référence interne du sujet, quels que soit son origine ethnique, ses assises culturelles ou son statut socio-économique. Une telle description phénoménologique capture “l’être au monde” particulier du sujet, notamment ses modèles internes, ses habitudes de fonctionnement (tant cognitifs qu’affectifs), ses modes de relation aux autres, et les thèmes qui, résonant avec le passé du sujet, provoquent des situations de conflit et des réactions défensives actuelles.

Le Rorschach facilite aussi l’étude du contexte culturel dans lequel une personne se reconstruit de manière constante et dynamique, en interaction avec les aspects favorisateurs ou inhibiteurs de la culture. Dans la tradition herméneutique, le Rorschach permet de reconstruire le monde du sens culturel appartenant à un événement, amenant l’investigateur à comprendre l’événement du point de vue de structure intrinsèque du monde dont l’événement tire son sens. Cette façon de procéder implique toutefois que le chercheur renonce à conceptualiser les aspects “déviants” d’un protocole comme indicateurs de psychopathologie pour les considérer au contraire comme une clé pour comprendre les caractéristiques fondamentales de la personnalité dans une culture donnée. Cela demande qu’on ne pense plus la culture en terme de biais qui menacent d’obscurcir la personnalité du sujet. Il faut au contraire faire porter son attention sur la richesse que les aspects culturels du fonctionnement psychique introduisent dans un protocole.

Ces réflexions nous ont été suggérées par une étude pilote portant sur les aspects du fonctionnement de la personnalité qui pourraient expliquer la participation de femmes dans la pratique de l’excision. Le groupe étudié, en 1995) était composé de 17 femmes originaires d’Afrique de l’Ouest qui vivent dans la région parisienne. Le Rorschach nous a fournit des données pertinentes concernant (1) un style particulier de fonctionnement cognitif et (2) l’émergence de l’excision comme thème essentiellement culturel.
Primary productivity in the Arctic Ocean: Impacts of complex optical properties and subsurface chlorophyll maxima on large‐scale estimates
Authors: Arrigo Kevin R. , Matrai Patricia A. , van Dijken Gert L.
Published: August 2011

The Arctic Ocean is an optically complex environment and presents unique challenges for ocean color satellite remote sensing. Phytoplankton pigment packaging, high concentrations of chromophoric dissolved organic matter (CDOM), and the frequent presence of subsurface chlorophyll a (Chl a) maxima (SCM), complicate satellite measurement of surface Chl a. However, the impact of likely errors in surface Chl a on satellite‐based estimates of depth‐integrated daily net primary production (NPP) have yet to be quantified. Here we use a large in situ Chl a and primary production database (ARCSS‐PP) to calculate the magnitude of the error that likely results from both omission of SCM and overestimated phytoplankton biomass when satellite‐based Chl a is used as input to an NPP algorithm. Results show that errors in pan‐Arctic NPP, due to omission of the SCM, increase from 0.2% in January to 16% in July and are largest in the Beaufort and Chukchi Sea. Over an annual cycle, the error is approximately 8%. Errors in regional NPP resulting from overestimates of surface Chl a by Sea‐viewing Wide Field‐of‐view Sensor can be larger, particularly when surface Chl a and NPP are low, but are partially offset by underestimates in NPP due to omission of NPP at the SCM. As a result, the combined effect of underestimates in NPP due to omission of the SCM and overestimates in NPP due to high satellite Chl a yields a total error in annual pan‐Arctic, depth‐integrated NPP of <1%. The reasons for this surprisingly low error are discussed.
Three‐dimensional transient hydraulic tomography in a highly heterogeneous glaciofluvial aquifer‐aquitard system
Authors: Berg Steven J. , Illman Walter A.
Published: August 2011

Hydraulic tomography has been proposed as an alternative site characterization method, however, relatively few field scale studies have been attempted. In this paper, we characterize the highly heterogeneous glaciofluvial aquifer‐aquitard system at the North Campus Research Site, located at the University of Waterloo, Waterloo, Ontario, Canada using transient hydraulic tomography (THT). In particular, we performed 9 pumping tests in a network of wells to image the hydraulic conductivity (K) and specific storage (Ss) distributions (or tomograms) as well as their uncertainties in three‐dimensions using the THT code of J. Zhu and T.‐C. J. Yeh (2005). We first performed stochastic inverse modeling of the 9 pumping tests individually to gain insight into the level of detail that can be imaged. Then, we sequentially included 4 of the pumping tests in a THT analysis. The resulting K and Ss tomograms were then validated visually by comparing them to stratigraphy and permeameter K estimates. The K and Ss tomograms were also rigorously assessed through the simulation of all 9 pumping tests and comparing the simulated and observed drawdowns. We find that performing the inversion with multiple pumping tests (i.e., hydraulic tomography) yields improved results when compared to the analysis of individual pumping tests.
Solute transport in the vadose zone and groundwater during flash floods
Authors: Amiaz Yanai , Sorek Shaul , Enzel Yehouda , Dahan Ofer
Published: August 2011

Water flow and solute transport in the vadose zone and groundwater during flood events were investigated in the lower reach of the Kuiseb River, Namibia, and in controlled column experiments. Simultaneous measurements of water level and electrical conductivity of the flood water in the stream channel and in the groundwater together with variations in the vadose zone water content, temperature, and pressure profiles allowed a detailed analysis of the various mechanisms governing solute transport in the subsurface during flash floods. The results indicated that on the land surface, flash floods emit, at their wetting fronts, instantaneous compression waves that propagate downward through the unsaturated zone to the water table. These compression waves generate abrupt solute‐displacement events in the groundwater immediately after the arrival of the flood on the land surface, long before deep percolation and groundwater recharge begin. Each flood event launches into the vadose zone a wetting front that propagates down through the vadose zone and recharges the groundwater upon arrival at the water table. The first wetting front of each flood season leaches out soluble salts that have accumulated in the vadose zone during the dry season. However, water percolation through the unsaturated zone does not leach out the entire soluble salt capacity of the sediment, even if percolation takes place under high water‐head flooding conditions for long periods. The incomplete leaching of the unsaturated zone by the percolating water releases soluble salts into the groundwater during every recharge event as a result of the rise of the water table into the vadose zone; this process results in a temporal increase of the groundwater electrical conductivity (EC).
Novel phytosynthesis of nanoparticles using Indigeneous Australian Plants
Authors: Tollamadugu N V K V Prasad , Kambala S R Venkata , Convery Benjamin , Naidu Ravi
Published: August 2011

Nanoparticles are considered to be the building blocks of nanotechnology. Biosynthesis of nanoparticles using plant material is an exciting and relatively new developing research area in nanobiotechnology. In the present study, Eucalyptus leaves were collected from Olive pink botanical garden, Alice Springs, Australia and were used to synthesize silver nanoparticles. Cubical structured and well monodispersed silver nanoparticles were formed with an average size of 50nm. The formed silver nanoparticles are found to have promising applications in medicine as good antimicrobial agents. To the best of our knowledge this is the first report on exploiting indigeneous Australian plant sources for the synthesis of metallic nanoparticles.
Hall mobility in multicrystalline silicon
Authors: Schindler F. , Geilker J. , Kwapil W. , Warta W. , Schubert M. C.
Published: August 2011

Knowledge of the carrier mobility in silicon is of utmost importance for photovoltaic applications, as it directly influences the diffusion length and thereby the cell efficiency. Moreover, its value is needed for a correct quantitative evaluation of a variety of lifetime measurements. However, models that describe the carrier mobility in silicon are based on theoretical calculations or fits to experimental data in monocrystalline silicon. Multicrystalline (mc) silicon features crystal defects such as dislocations and grain boundaries, with the latter possibly leading to potential barriers through the trapping of charge carriers and thereby influencing the mobility, as shown, for example, by Maruska et al. [Appl. Phys. Lett. 36, 381 (1980)]. To quantify the mobilities in multicrystalline silicon, we performed Hall measurements in p-type mc-Si samples of various resistivities and different crystal structures and compared the data to majority carrier Hall mobilities in p-type monocrystalline floatzone (FZ) silicon. For lack of a model that provides reliable values of the Hall mobility in silicon, an empirical fit similar to existing models for conductivity mobilities is proposed based on Hall measurements of monocrystalline p-type FZ silicon. By comparing the measured Hall mobilities obtained from mc silicon with the corresponding Hall mobilities in monocrystalline silicon of the same resistivity, we found that the mobility reduction due to the presence of crystal defects in mc-Si ranges between 0% and 5% only. Mobility decreases of up to 30% as reported by Peter et al. [Proceedings of the 23rd European Photovoltaic Solar Energy Conference, Valencia, Spain, 1–5 September 2008], or even of a factor of 2 to 3 as detected by Palais et al. [Mater. Sci. Eng. B 102, 184 (2003)], in multicrystalline silicon were not observed.
Exponential operators and the algebraic description of quantum confined systems
Authors: Aleixo A. N. F. , Balantekin A. B.
Published: August 2011

We study the relations and transformations produced by exponential operators, the argument of which are dependent on the basic algebraic elements of supersymmetric and shape-invariant potential systems, and obtain explicit expressions. We apply our results to self-similar potential systems and to a set of translational shape-invariant systems, including the Morse, Pöschl-Teller, Scarf, and Rosen-Morse potentials, and obtain closed-form expressions. We show that our results reproduce those obtained for the harmonic oscillator in the appropriate limits.
Dissociation energy and vibrational predissociation dynamics of the ammonia dimer
Authors: Case Amanda S. , Heid Cornelia G. , Kable Scott H. , Crim F. Fleming
Published: August 2011

Experiments using infrared excitation of either the intramolecular symmetric N-H stretch (νNH,S) or the intramolecular antisymmetric N-H stretch (νNH,A) of the ammonia dimer ((NH3)2) in combination with velocity-map ion imaging provide new information on the dissociation energy of the dimer and on the energy disposal in its dissociation. Ion imaging using resonance enhanced multiphoton ionization to probe individual rovibrational states of one of the ammonia monomer fragments provides recoil speed distributions. Analyzing these distributions for different product states gives a dissociation energy of D0 = 660 ± 20 cm−1 for the dimer. Fitting the distributions shows that rotations are excited up to their energetic limit and determines the correlation of the fragment vibrations. The fragments NH3(v2 = 3+) and NH3(v2 = 2+) have a vibrational ground-state partner NH3(v = 0), but NH3(v2 = 1+) appears in partnership with another fragment in v2 = 1. This propensity is consistent with the idea of minimizing the momentum gap between the initial and final states by depositing a substantial fraction of the available energy into internal excitation.
Highly tunable microwave stub resonator on ferroelectric KTa0.5Nb0.5O3 thin film
Authors: Simon Q. , Corredores Y. , Castel X. , Benzerga R. , Sauleau R. , Mahdjoubi K. , Le Febvrier A. , Députier S. , Guilloux-Viry M. , Zhang L. , Laurent P. , Tanné G.
Published: August 2011

A coplanar waveguide (CPW) stub resonator has been fabricated on a pulsed-laser deposited KTa0.5Nb0.5O3 (KTN) thin film (600 nm-thick) onto a r-plane sapphire substrate. It was designed to operate at 10 GHz when the applied bias voltage is zero. We show experimentally that the resonance frequency is shifted by 44% under a 70 kV/cm DC applied electric field. In addition, the dielectric characteristics of the KTN film have been assessed through post-processed measurements of CPW 50-Ω transmission lines using the conformal mapping method.
The effect of the trap density and depth on the current bistability in organic bistable devices
Authors: Jung Jae Hun , Kim Tae Whan
Published: August 2011

Current-voltage (I-V) characteristics and trap densities of organic bistable devices (OBDs) fabricated utilizing SnO2 nanoparticles embedded in a polymer layer in the framework of the space-charge limited current (SCLC) model were calculated in order to investigate the transition mechanisms of the states and to compare the values with the experimental I-V curves of the fabricated OBDs. The effect of the trap density and depth on the current bistability in OBDs with a single layer was simulated using the Poisson equation, the drift equation, and the single-level trap model. The slope of the current variation for OBDs in the low conductivity (OFF) state was between 2 and 3, and that for the devices in the high conductivity (ON) state was 2, indicative of the appearance of a SCLC. The ON/OFF conductivity ratio of the OBDs was approximately 102. Because the electron occupation probability increased with increasing trap depth, the number of electrons trapped in the organic layer increased, resulting in an increase in the ON/OFF ratio of the current bistability. The experimental I-V curves for OBDs were in reasonable agreement with the theoretical I-V curves obtained by using a simulation method.
Electromechanical properties of Al0.9Sc0.1N thin films evaluated at 2.5 GHz film bulk acoustic resonators
Authors: Matloub Ramin , Artieda Alvaro , Sandu Cosmin , Milyutin Evgeny , Muralt Paul
Published: August 2011

AlN films are employed in RF filters for wireless communication. We report on enhanced coupling factors kt2 obtained by partial substitution of Al by Sc. Al0.88Sc0.12N films were deposited by reactive magnetron sputtering from an Al0.9Sc0.1 alloy target. They grew in the piezoelectric wurtzite phase with a similar microstructure as pure AlN films. The clamped d33,f increased considerably from 5.1 to 7.8 pm/V. The admittance measured at thin film bulk acoustic wave resonators was fitted to an equivalent circuit model and to 2-dimensional finite element simulation, yielding a kt2 of 7.3% and a quality factor of 650. The material softens considerably.
Simulation of helically wrapped, compact heat exchangers
Authors: Gorman John , Sparrow Ephraim , Mowry Greg , Abraham John
Published: August 2011

A new category of heat exchanger has been invented which fulfills the dual requirements of compactness and high thermal efficiency. The underlying principle of the exchanger is the helical intertwining of the tubes which carry the participating fluids. To ensure a thermal bridge of high conductivity between the tubes, silver braze was introduced into the interstitial space. Numerical simulation was used to characterize the performance of this category of heat exchanger. The simulation model is three-dimensional for both fluid flow and heat transfer and is also conjugate in that it encompasses two flow passages, their walls, and the interconnecting silver braze. A fabrication means was also developed. Numerical results were obtained for two general classes of heat exchange situations, one of which dealt with single-phase flows while the other related to two-phase flows. The single-phase situation investigated here is a water-water heat exchanger. The heat exchange effectivenesses evaluated from the numerical simulations demonstrated a level of enhancement of 84% compared to a baseline case consisting of straight flow passages. This level of enhancement is substantially higher than that achieved by other modes of augmentation. The results also showed that further enhancements can be achieved by increasing the number of helical turns per unit length. Experimentation was used to validate the basic computational model. For a given physical situation, the measured relationship between volumetric fluid flow and pressure drop was compared with that predicted by the numerical simulation. The excellence of the agreement lends strong support to the physical principles that underlie the simulation model
Graphene bubbles with controllable curvature
Authors: Georgiou T. , Britnell L. , Blake P. , Gorbachev R. V. , Gholinia A. , Geim A. K. , Casiraghi C. , Novoselov K. S.
Published: August 2011

Raised above the substrate and elastically deformed areas of graphene in the form of bubbles are found on different substrates. They come in a variety of shapes, including those which allow strong modification of the electronic properties of graphene. We show that the shape of the bubble can be controlled by an external electric field. This effect can be used to make graphene-based adaptive focus lenses.
Temperature dependences of the spin transfer torque and tunneling magneto-resistance in magnetic metallic and tunneling junctions
Authors: You Chun-Yeol , Song Seung-Ho , Kim Hyungsuk
Published: August 2011

We investigate temperature dependences of the spin transfer torque (STT) and tunneling magnetoresistance (TMR) in the magnetic metallic junction (MMJ) and magnetic tunneling junction (MTJ). The temperature dependences of the in-plane and out-of-plane STTs are calculated with the Keldysh non-equilibrium Green’s function method. We find that the temperature dependences of the in-plane and out-of-plane STTs for MTJ are strikingly deviated from the previous prediction [P. Bruno, Phys. Rev. B 52, 411 (1995)] for the interlayer exchange coupling, while ones for MMJ are well agreed with the prediction. Furthermore, the temperature dependences of the in-plane and out-of-plane STTs are varied with the bias voltage in different ways.
Magnetic switching fluctuations from sidewall oxides in MgO/FeCoB magnetic tunnel junctions
Authors: Pomeroy J. M. , Read J. C.
Published: August 2011

Sharp magnetic switching distributions with coupling to magnetic sidewall oxides in FeCoB/MgO magnetic tunnel junctions (MTJs) are revealed by magneto-resistance first order reversal curve (MR-FORC) measurements. Tunneling magneto-resistance (TMR) and FORC data in units of % TMR/mT2 are shown for two identical devices that differ only by the annealing. The annealed sample has much larger TMR and correspondingly higher switching density ρ. In both cases, the MR-FORC data exhibit a prominent “checkerboard” pattern that implies coupling to magnetic oxides on the MTJ sidewalls.
Strain modulated magnetization and colossal resistivity of epitaxial La2/3Ca1/3MnO3 film on BaTiO3 substrate
Authors: Cheng Z. X. , Wang X. L. , Dou S. X. , Osada M. , Kimura H.
Published: August 2011

A sharp drop in resistance and a magnetization anomaly have been observed in La2/3Ca1/3MnO3 film in zero magnetic field at the BaTiO3 substrate structural phase transition temperature, due to the substrate clamping/strain effect, which is confirmed by Raman scattering. However, the anomalies for both resistance and magnetization were eliminated by a strong external magnetic field. These phenomena indicate that strain can cause colossal resistance and a change in magnetization which resembles the magnetic field effect. The interplay of the external forces (strain and magnetic field) is a good demonstration of the strong coupling between spin and lattice in colossal magnetoresistance materials.
Realization of a narrowband single wavelength microring mirror
Authors: Arbabi Amir , Kang Young Mo , Lu Ching-Ying , Chow Edmond , Goddard Lynford L.
Published: August 2011

We present a small footprint narrowband on-chip mirror made by integration of a distributed Bragg reflector (DBR) inside a microring resonator. The DBR covers half of the ring’s circumference and is only reflective at one of the ring resonances. Design, fabrication, and characterization of the proposed device are presented. A single reflection peak with maximum power reflectivity of 92.3% and full width at half maximum of 0.4 nm is demonstrated. The device has potential application as an in-line mirror for low-threshold, narrow linewidth single mode laser diodes.
Communication: Extended multi-state complete active space second-order perturbation theory: Energy and nuclear gradients
Authors: Shiozaki Toru , Győrffy Werner , Celani Paolo , Werner Hans-Joachim
Published: August 2011

The extended multireference quasi-degenerate perturbation theory, proposed by Granovsky [J. Chem. Phys. 134, 214113 (2011)], is combined with internally contracted multi-state complete active space second-order perturbation theory (XMS-CASPT2). The first-order wavefunction is expanded in terms of the union of internally contracted basis functions generated from all the reference functions, which guarantees invariance of the theory with respect to unitary rotations of the reference functions. The method yields improved potentials in the vicinity of avoided crossings and conical intersections. The theory for computing nuclear energy gradients for MS-CASPT2 and XMS-CASPT2 is also presented and the first implementation of these gradient methods is reported. A number of illustrative applications of the new methods are presented.
Nurture affects gender differences in spatial abilities
Authors: Hoffman Moshe , Gneezy Uri , List John A.
Published: August 2011

Women remain significantly underrepresented in the science, engineering, and technology workforce. Some have argued that spatial ability differences, which represent the most persistent gender differences in the cognitive literature, are partly responsible for this gap
.
The underlying forces at work shaping the observed spatial ability differences revolve naturally around the relative roles of nature and nurture. Although these forces remain among the most hotly debated in all of the sciences, the evidence for nurture is tenuous, because it is difficult to compare gender differences among biologically similar groups with distinct nurture. In this study, we use a large-scale incentivized experiment with nearly 1,300 participants to show that the gender gap in spatial abilities, measured by time to solve a puzzle, disappears when we move from a patrilineal society to an adjoining matrilineal society. We also show that about one-third of the effect can be explained by differences in education. Given that none of our participants have experience with puzzle solving and that villagers from both societies have the same means of subsistence and shared genetic background, we argue that these results show the role of nurture in the gender gap in cognitive abilities.
Role of stochastic processes in maintaining discrete strain structure in antigenically diverse pathogen populations
Authors: Buckee Caroline O. , Recker Mario , Watkins Eleanor R. , Gupta Sunetra
Published: August 2011

Many highly diverse pathogen populations appear to exist stably as discrete antigenic types despite evidence of genetic exchange. It has been shown that this may arise as a consequence of immune selection on pathogen populations, causing them to segregate permanently into discrete nonoverlapping subsets of antigenic variants to minimize competition for available hosts. However, discrete antigenic strain structure tends to break down under conditions where there are unequal numbers of allelic variants at each locus. Here, we show that the inclusion of stochastic processes can lead to the stable recovery of discrete strain structure through loss of certain alleles. This explains how pathogen populations may continue to behave as independently transmitted strains despite inevitable asymmetries in allelic diversity of major antigens. We present evidence for this type of structuring across global meningococcal isolates in three diverse antigens that are currently being developed as vaccine components.
The mammalian target of rapamycin regulates cholesterol biosynthetic gene expression and exhibits a rapamycin-resistant transcriptional profile
Authors: Wang Beatrice T. , Ducker Gregory S. , Barczak Andrea J. , Barbeau Rebecca , Erle David J. , Shokat Kevan M.
Published: August 2011

The mammalian target of rapamycin (mTOR) is a central regulator of cell growth and proliferation in response to growth factor and nutrient signaling. Consequently, this kinase is implicated in metabolic diseases including cancer and diabetes, so there is great interest in understanding the complete spectrum of mTOR-regulated networks. mTOR exists in two functionally distinct complexes, mTORC1 and mTORC2, and whereas the natural product rapamycin inhibits only a subset of mTORC1 functions, recently developed ATP-competitive mTOR inhibitors have revealed new roles for both complexes. A number of studies have highlighted mTORC1 as a regulator of lipid homeostasis. We show that the ATP-competitive inhibitor PP242, but not rapamycin, significantly down-regulates cholesterol biosynthesis genes in a 4E-BP1–dependent manner in NIH 3T3 cells, whereas S6 kinase 1 is the dominant regulator in hepatocellular carcinoma cells. To identify other rapamycin-resistant transcriptional outputs of mTOR, we compared the expression profiles of NIH 3T3 cells treated with rapamycin versus PP242. PP242 caused 1,666 genes to be differentially expressed whereas rapamycin affected only 88 genes. Our analysis provides a genomewide view of the transcriptional outputs of mTOR signaling that are insensitive to rapamycin.
The motor origins of human and avian song structure
Authors: Tierney Adam T. , Russo Frank A. , Patel Aniruddh D.
Published: August 2011

Human song exhibits great structural diversity, yet certain aspects of melodic shape (how pitch is patterned over time) are widespread. These include a predominance of arch-shaped and descending melodic contours in musical phrases, a tendency for phrase-final notes to be relatively long, and a bias toward small pitch movements between adjacent notes in a melody [Huron D (2006)
Sweet Anticipation: Music and the Psychology of Expectation
(MIT Press, Cambridge, MA)]. What is the origin of these features? We hypothesize that they stem from motor constraints on song production (i.e., the energetic efficiency of their underlying motor actions) rather than being innately specified. One prediction of this hypothesis is that any animals subject to similar motor constraints on song will exhibit similar melodic shapes, no matter how distantly related those animals are to humans. Conversely, animals who do not share similar motor constraints on song will not exhibit convergent melodic shapes. Birds provide an ideal case for testing these predictions, because their peripheral mechanisms of song production have both notable similarities and differences from human vocal mechanisms [Riede T, Goller F (2010)
Brain Lang
115:69–80]. We use these similarities and differences to make specific predictions about shared and distinct features of human and avian song structure and find that these predictions are confirmed by empirical analysis of diverse human and avian song samples.
Fluid forces control endothelial sprouting
Authors: Song Jonathan W. , Munn Lance L.
Published: August 2011

During angiogenesis, endothelial cells (ECs) from intact blood vessels quickly infiltrate avascular regions via vascular sprouting. This process is fundamental to many normal and pathological processes such as wound healing and tumor growth, but its initiation and control are poorly understood. Vascular endothelial cell growth factor (VEGF) can promote vessel dilation and angiogenic sprouting, but given the complex nature of vascular morphogenesis, additional signals are likely necessary to determine, for example, which vessel segments sprout, which dilate, and which remain quiescent. Fluid forces exerted by blood and plasma are prime candidates that might codirect these processes, but it is not known whether VEGF cooperates with mechanical fluid forces to mediate angiogenesis. Using a microfluidic tissue analog of angiogenic sprouting, we found that fluid shear stress, such as exerted by flowing blood, attenuates EC sprouting in a nitric oxide-dependent manner and that interstitial flow, such as produced by extravasating plasma, directs endothelial morphogenesis and sprout formation. Furthermore, positive VEGF gradients initiated sprouting but negative gradients inhibited sprouting, promoting instead sheet-like migration analogous to vessel dilation. These results suggest that ECs integrate signals from fluid forces and local VEGF gradients to achieve such varied goals as vessel dilation and sprouting.