bluuebunny/crossref_metadata_2025 huggingface dataset:
Narrative of a Voyage to the Ethiopic and South Atlantic Ocean, Indian Ocean, Chinese Sea, North and South Pacific Oceans in the Years 1829, 1830, 1831
Authors: Morrell Abby Jane
Published: May 2013

Abby Jane Morrell (b. 1809) was the wife of ship captain and explorer Benjamin Morrell (1795–1839). During the nineteenth century it became more common for women to join their husbands on voyages, and Abby insisted on accompanying her husband on his fourth voyage. They left America for the Pacific in 1829 on board the Antarctic, which visited the Auckland Islands and Pacific Islands in search of commercial gain, before returning via the Azores in 1831. First published in 1833, this is Abby's account of their journey. It was ghostwritten by the American author Samuel Knapp (1783−1838) and followed the publication of Benjamin Morrell's own account as part of A Narrative of Four Voyages (also reissued in this series). It includes an account of the violent conflicts with the inhabitants of some of the Pacific Islands, and also contains Abby's comments on the 'amelioration of the condition of American Seamen'.
An Account of the Petrological, Botanical, and Zoological Collection Made in Kerguelen's Land and Rodriguez during the Transit of Venus Expeditions 1874–75
Authors: Eaton Alfred Edwin
Published: May 2013

The Kerguelen Islands, known also as the Desolation Islands, lie in the extreme south of the Indian Ocean. By the late nineteenth century they were still relatively unexplored, but they represented a fascinating puzzle: although the Islands were four thousand miles away from South America, they shared the same species of flora. Rodrigues, an island off the coast of Madagascar, was also a point of increasing interest among naturalists. While most archipelagic islands then discovered were volcanic, explorers noted that the caves of Rodrigues were formed of limestone, and that most local species were not indigenous. Like the Kerguelen Islands, they provided some of the first clear evidence that modern sea-levels were much altered from those of prehistory. Naturalists visited both locations as part of the expeditions to study the transit of Venus in 1874. Originally published in 1879, this collection of essays is a comprehensive catalogue of their findings.
Transient growth in the flow past a three-dimensional smooth roughness element
Authors: Cherubini S. , De Tullio M. D. , De Palma P. , Pascazio G.
Published: May 2013

This work provides a global optimization analysis, looking for perturbations inducing the largest energy growth at a finite time in a boundary-layer flow in the presence of smooth three-dimensional roughness elements. Amplification mechanisms are described which can bypass the asymptotical growth of Tollmien–Schlichting waves. Smooth axisymmetric roughness elements of different height have been studied, at different Reynolds numbers. The results show that even very small roughness elements, inducing only a weak deformation of the base flow, can localize the optimal disturbance characterizing the Blasius boundary-layer flow. Moreover, for large enough bump heights and Reynolds numbers, a strong amplification mechanism has been recovered, inducing an increase of several orders of magnitude of the energy gain with respect to the Blasius case. In particular, the highest value of the energy gain is obtained for an initial varicose perturbation, differently to what found for a streaky parallel flow. Optimal varicose perturbations grow very rapidly by transporting the strong wall-normal shear of the base flow, which is localized in the wake of the bump. Such optimal disturbances are found to lead to transition for initial energies and amplitudes considerably smaller than sinuous optimal ones, inducing hairpin vortices downstream of the roughness element.
Genetic predisposition to obesity and lifestyle factors – the combined analyses of twenty-six known BMI- and fourteen known waist:hip ratio (WHR)-associated variants in the Finnish Diabetes Prevention Study
Authors: Jääskeläinen Tiina , Paananen Jussi , Lindström Jaana , Eriksson Johan G. , Tuomilehto Jaakko , Uusitupa Matti ,   for the Finnish Diabetes Prevention Study Group
Published: May 2013

Recent genome-wide association studies have identified multiple loci associated with BMI or the waist:hip ratio (WHR). However, evidence on gene–lifestyle interactions is still scarce, and investigation of the effects of well-documented dietary and other lifestyle data is warranted to assess whether genetic risk can be modified by lifestyle. We assessed whether previously established BMI and WHR genetic variants associate with obesity and weight change in the Finnish Diabetes Prevention Study, and whether the associations are modified by dietary factors or physical activity. Individuals (n 459) completed a 3 d food record and were genotyped for twenty-six BMI- and fourteen WHR-related variants. The effects of the variants individually and in combination were investigated in relation to obesity and to 1- and 3-year weight change by calculating genetic risk scores (GRS). The GRS were separately calculated for BMI and the WHR by summing the increasing alleles weighted by their published effect sizes. At baseline, the GRS were not associated with total intakes of energy, macronutrients or fibre. The mean 1- and 3-year weight changes were not affected by the BMI or WHR GRS. During the 3-year follow-up, a trend for higher BMI by the GRS was detected especially in those who reported a diet low in fibre (P for interaction = 0·065). Based on the present findings, it appears unlikely that obesity-predisposing variants substantially modify the effect of lifestyle modification on the success of weight reduction in the long term. In addition, these findings suggest that the association between the BMI-related genetic variants and obesity could be modulated by the diet.
Samuel Butler and the Site of Scheria
Authors: Pocock L. G.
Published: May 2013

In all European literature there is nothing more justly famous than Odysseus' meeting with Nausicaa in Bk. vi of the Odyssey. Editors of the Odyssey from antiquity to the present day have agreed in regarding the land of the Phaeacians and Scheria, their city, as an imaginary place, although it is remarked from time to time that it may be drawn from some real place and the Phaeacians from a real people. But there is in fact sufficient internal evidence in the poem to prove beyond any reasonable doubt that Scheria is to be identified with Trapani in northwestern Sicily. The extraordinary thing is that no one ever realized this seemingly obvious fact or sought to make the identification until Samuel Butler did so some sixty years ago. His book, The Authoress of the Odyssey, published in 1897, was, however, so badly received that all its contents, good and bad alike, were rejected as so much rubbish. The only informed consideration his theories have ever received came from Professor Farrington (recently retired from the University College of Swansea), who wrote in general support of them in 1929, when lecturer at Cape Town University. No one, so far as the author of this article has been able to ascertain, has ever so much as paid a visit to Trapani in order to see Butler's country and to check his facts, until he and his son did so in the summer of 1952.
‘LET US SWIM IN THE POOL OF LOVE’: LOVE LETTERS AND DISCOURSES OF COMMUNITY COMPOSITION IN TWENTIETH-CENTURY TANZANIA
Authors: Prichard Andreana C.
Published: May 2013

This article uses a series of love letters exchanged between an African Anglican priest and a teacher-in-training before their marriage to investigate the relationship between the fashioning of the individual self, marriage, and community at the dawn of Tanganyika's independence. When seen through marriage's historical position as an institution central to community composition, these letters illustrate how the family – and the intimate process of building families – could become an alternate site of national imagination. These two young lovers understood their marriage as an explicitly political act of community composition, and cast themselves as characters in the drama of national imagination. In negotiating their twentieth-century marriage, Rose and Gideon became political innovators, selecting, producing, and testing the content and boundaries of the nation.
n-3 Fatty acids, inflammation and immunity: new mechanisms to explain old actions
Authors: Calder Philip C.
Published: May 2013

Numerous effects ofn-3 fatty acids EPA and DHA on functional responses of cells involved in inflammation and immunity have been described. Fatty acid-induced modifications in membrane order and in the availability of substrates for eicosanoid synthesis are long-standing mechanisms that are considered important in explaining the effects observed. More recently, effects on signal transduction pathways and on gene expression profiles have been identified. Over the last 10 years or so, significant advances in understanding the mechanisms of action ofn-3 fatty acids have been made. These include the identification of new actions of lipid mediators that were already described and of novel interactions among those mediators and the description of an entirely new family of lipid mediators, resolvins and protectins that have anti-inflammatory actions and are critical to the resolution of inflammation. It is also recognised that EPA and DHA can inhibit activation of the prototypical inflammatory transcription factor NF-κB. Recent studies suggest three alternative mechanisms by whichn-3 fatty acids might have this effect. Within T-cells, as well as other cells of relevance to immune and inflammatory responses, EPA and DHA act to disrupt very early events involving formation of the structures termed lipid rafts which bring together various proteins to form an effective signalling platform. In summary, recent research has identified a number of new mechanisms of action that help to explain previously identified effects ofn-3 fatty acids on inflammation and immunity.
Identification of a newSchistosoma mansoniSMYB1 partner: putative roles in RNA metabolism
Authors: ROCHA ELIZÂNGELA A. , VALADÃO ANALINA F. , REZENDE CÍNTIA M. , DIAS SILVIA REGINA COSTA , MACEDO ANDRÉA M. , MACHADO CARLOS R. , FANTAPPIÉ MARCELO R. , RUMJANEK FRANKLIN D. , GOES ALFREDO M. , GOMES DAWIDSON A. , LOVERDE PHILIP T. , DRUMMOND MARCELA G. , FRANCO GLÓRIA R.
Published: May 2013

SMYB1 is aSchistosoma mansoniprotein highly similar to members of the Y-box binding protein family. Similar to other homologues, SMYB1 is able to bind double- and single-stranded DNA, as well as RNA molecules. The characterization of proteins involved in the regulation of gene expression inS. mansoniis of great importance for the understanding of molecular events that control morphological and physiological changes in this parasite. Here we demonstrate that SMYB1 is located in the cytoplasm of cells from different life-cycle stages ofS. mansoni, suggesting that this protein is probably acting in mRNA metabolism in the cytoplasm and corroborating previous findings from our group that showed its ability to bind RNA. Protein–protein interactions are important events in all biological processes, since most proteins execute their functions through large supramolecular structures. Yeast two-hybrid screenings using SMYB1 as bait identified a partner inS. mansonisimilar to the SmD3 protein ofDrosophila melanogaster(SmRNP), which is important in the assembly of small nuclear ribonucleoprotein complexes. Also, pull-down assays were conducted using immobilized GST-SMYB1 proteins and confirmed the SMYB1-SmRNP interaction. The interaction of SMYB1 with a protein involved in mRNA processing suggests that it may act in processes such as turnover, transport and stabilization of RNA molecules.
Religious classical practice: Entextualisation and performance
Authors: Rosowsky Andrey
Published: May 2013

This article considers a particular contextualisation of the religious classical and practices associated with it within broader sets of linguistic resources or repertoires. Through a description and analysis of religious classical practices occurring in multilingual urban settings in the UK, the article employs the interpretive frame of performance to account for practice. An introductory overview of religious classical practices is provided, which is followed by a brief discussion of the theoretical considerations surrounding performance and entextualisation. This is followed by the sharing of ethnographic data that aim to demonstrate the performance-oriented and highly entextualised nature of religious classical practice. The article concludes with the suggestion that the latter is an example not only of a set of linguistic resources used predominantly for performative practice but has more in common with scripted theatrical performance than with other conventionally referential communicative practices. (Religious classical, language variety, performance, entextualisation, linguistic resources, linguistic repertoire, Muslim, multilingualism, practice)*
At home in the quantum world
Authors: Atmanspacher Harald
Published: May 2013

One among many misleading quotations about the alleged mysteries of quantum theory is from Feynman (1965): “I think I can safely say that nobody understands quantum mechanics.” Today we know that quantum theory describes many aspects of our world in a fully intelligible fashion. Pothos & Busemeyer (P&B) propose ways in which this may include psychology and cognitive science.
Signal detection theory in Hilbert space
Authors: Baldo Marcus Vinícius C.
Published: May 2013

The Hilbert space formalism is a powerful language to express many cognitive phenomena. Here, relevant concepts from signal detection theory are recast in that language, allowing an empirically testable extension of the quantum probability formalism to psychophysical measures, such as detectability and discriminability.
Quantum mathematical cognition requires quantum brain biology: The “Orch OR” theory
Authors: Hameroff Stuart R.
Published: May 2013

The “Orch OR” theory suggests that quantum computations in brain neuronal dendritic-somatic microtubules regulate axonal firings to control conscious behavior. Within microtubule subunit proteins, collective dipoles in arrays of contiguous amino acid electron clouds enable “quantum channels” suitable for topological dipole “qubits” able to physically represent cognitive values, for example, those portrayed by Pothos & Busemeyer (P&B) as projections in abstract Hilbert space.
Quantum probability and conceptual combination in conjunctions
Authors: Hampton James A.
Published: May 2013

I consider the general problem of category conjunctions in the light of Pothos & Busemeyer (P&B)'s quantum probability (QP) account of the conjunction fallacy. I argue that their account as presented cannot capture the “guppy effect” – the case in which a class is a better member of a conjunction A^B than it is of either A or B alone.
Is quantum probability rational?
Authors: Houston Alasdair I. , Wiesner Karoline
Published: May 2013

We concentrate on two aspects of the article by Pothos & Busemeyer (P&B): the relationship between classical and quantum probability and quantum probability as a basis for rational decisions. We argue that the mathematical relationship between classical and quantum probability is not quite what the authors claim. Furthermore, it might be premature to regard quantum probability as the best practical rational scheme for decision making.
Limitations of the Dirac formalism as a descriptive framework for cognition
Authors: Kaznatcheev Artem , Shultz Thomas R.
Published: May 2013

We highlight methodological and theoretical limitations of the authors' Dirac formalism and suggest the von Neumann open systems approach as a resolution. The open systems framework is a generalization of classical probability and we hope it will allow cognitive scientists to extend quantum probability from perception, categorization, memory, decision making, and similarity judgments to phenomena in learning and development.
Quantum probability, intuition, and human rationality
Authors: Oaksford Mike
Published: May 2013

This comment suggests that Pothos & Busmeyer (P&B) do not provide an intuitive rational foundation for quantum probability (QP) theory to parallel standard logic and classical probability (CP) theory. In particular, the intuitive foundation for standard logic, which underpins CP, is the elimination of contradictions – that is, believingpand not-pis bad. Quantum logic, which underpins QP, explicitly denies non-contradiction, which seems deeply counterintuitive for the macroscopic world about which people must reason. I propose a possible resolution in situation theory.
Grounding quantum probability in psychological mechanism
Authors: Love Bradley C.
Published: May 2013

Pothos & Busemeyer (P&B) provide a compelling case that quantum probability (QP) theory is a better match to human judgment than is classical probability (CP) theory. However, any theory (QP, CP, or other) phrased solely at the computational level runs the risk of being underconstrained. One suggestion is to ground QP accounts in mechanism, to leverage a wide range of process-level data.
Disentangling the order effect from the context effect: Analogies, homologies, and quantum probability
Authors: Khalil Elias L.
Published: May 2013

Although the quantum probability (QP) can be useful to model the context effect, it is not relevant to the order effect, conjunction fallacy, and other related biases. Although the issue of potentiality, which is the intuition behind QP, is involved in the context effect, it is not involved in the other biases.
Online Victim Tracking and Tracing System (ViTTS) for Major Incident Casualties
Authors: Marres Geertruid M.H. , Taal Luc , Bemelman Michael , Bouman Jos , Leenen Luke P.H.
Published: May 2013

Introduction

Dealing with major incidents requires an immediate and coordinated response by multiple organizations. Communicating and coordinating over multiple geographical locations and organizations is a complex process. One of the greatest challenges is patient tracking and tracing. Often, data about the number of victims, their condition, location and transport is lacking. This hinders an effective response and causes public distress. To address this problem, a Victim Tracing and Tracking system (ViTTS) was developed.

Methods

An online ViTTS was developed based on a wireless network with routers on ambulances, and direct online registration of victims and their triage data through barcode injury cards. The system was tested for feasibility and usability during disaster drills.

Results

The formation of a local radio network of hotspots with mobile routers and connection over General Packet Radio Service (GPRS) to the central database worked well. ViTTS produced accurately stored data, real-time availability, and a real-time overview of the patients (number, seriousness of injury, and location).

Conclusion

The ViTTS provides a system for early, unique registration of victims close to the impact site. Online application and connection of the various systems used by the different chains in disaster relief promotes interoperability and enables patient tracking and tracing. It offers a real-time overview of victims to all involved disaster relief partners, which is necessary to generate an adequate disaster response.

MarresGMH, TaalL, BemelmanM, BoumanJ, LeenenLPH. Online Victim Tracking and Tracing System (ViTTS) for major incident casualties. Prehosp Disaster Med. 2013;28(4):1-9.
Atomic-Scale Tomography: A 2020 Vision
Authors: Kelly Thomas F. , Miller Michael K. , Rajan Krishna , Ringer Simon P.
Published: May 2013

Atomic-scale tomography (AST) is defined and its place in microscopy is considered. Arguments are made that AST, as defined, would be the ultimate microscopy. The available pathways for achieving AST are examined and we conclude that atom probe tomography (APT) may be a viable basis for AST on its own and that APT in conjunction with transmission electron microscopy is a likely path as well. Some possible configurations of instrumentation for achieving AST are described. The concept of metaimages is introduced where data from multiple techniques are melded to create synergies in a multidimensional data structure. When coupled with integrated computational materials engineering, structure–properties microscopy is envisioned. The implications of AST for science and technology are explored.
A head-to-head randomized clinical trial of methylphenidate and atomoxetine treatment for executive function in adults with attention-deficit hyperactivity disorder
Authors: Ni Hsing-Chang , Shang Chi-Yung , Gau Susan Shur-Fen , Lin Yu-Ju , Huang Hui-Chun , Yang Li-Kuang
Published: May 2013

Results regarding the effects of methylphenidate and atomoxetine on executive functions were inconsistent and no study has directly compared the efficacy of these two medications in improving executive functions in adults with attention-deficit hyperactivity disorder (ADHD). We conducted an 8–10 wk, open-label, head-to-head, randomized clinical trial involving adults with a clinical diagnosis of ADHD confirmed by psychiatric interview. The two treatment arms were immediate-release methylphenidate (IR-methylphenidate) (n = 31) and atomoxetine once daily (n = 32). Executive functions were assessed by the Cambridge Neuropsychological Test Automated Battery (CANTAB), including spatial working memory, spatial span, intra-extra dimensional set shifts, rapid visual information processing and Stockings of Cambridge (SOC). In addition to the symptom assessments at baseline (week 0), visit 2 (week 4–5) and visit 3 (week 8–10), they received CANTAB assessments at baseline and visit 3 (60.4 ± 6.3 d). Compared to baseline, adults treated with atomoxetine showed significant improvement in spatial working memory, spatial short-term memory, sustained attention and spatial planning at visit 3; adults treated with IR-methylphenidate showed significant improvement in spatial working memory at visit 3. Comparing the magnitude of improvement in executive functions between these two medications, the effect was generally similar for the two groups, although atomoxetine might have significantly greater efficacy than IR-methylphenidate in terms of improving spatial planning (SOC). Our results provide evidence to support that both IR-methylphenidate and atomoxetine improved various executive functions in adults with ADHD with greater improvement in atomoxetine than IR-methylphenidate in spatial planning.
Do residents need end-of-life care training?
Authors: Litauska Agata Marszalek , Kozikowski Andrzej , Nouryan Christian N. , Kline Myriam , Pekmezaris Renee , Wolf-Klein Gisele
Published: May 2013

Objective:

As medical education evolves, emphasis on chronic care management within the medical curriculum becomes essential. Because of the consistent lack of appropriate end-of-life care training, far too many patients die without the benefits of hospice care. This study explores the association between physician knowledge, training status, and level of comfort with hospice care referral of terminally ill patients.

Method:

In 2011, anonymous surveys were distributed to physicians in postgraduate years 1, 2, and 3; fellows; hospital attending physicians; specialists; and other healthcare professionals in five hospitals of a large health system in New York. Demographic comparisons were performed using χ2 and Fisher's exact tests. Spearman correlations were calculated to determine if professional status and experience were associated with comfort and knowledge discussing end-of-life topics with terminal patients.

Results:

The sample consisted of 280 participants (46.7% response rate). Almost a quarter (22%) did not know key hospice referral criteria. Although 88% of respondents felt that knowledge of hospice care is an important competence, 53.2% still relinquished advance directives discussion to emergency room (ER) physicians. Fear of patient/family anger was the most frequently reported hospice referral barrier, although 96% of physicians rarely experienced reprisals. Physician comfort level discussing end-of-life issues and hospice referral was significantly associated with the number of years practicing medicine and professional status.

Significance of results:

Physicians continue to relinquish end-of-life care to ER staff and palliative care consultants. Exploring unfounded and preconceived fears associated with hospice referral needs to be integrated into the curriculum, to prepare future generations of physicians. Medical education should focus on delivering the right amount of end-of-life care training, at the right time, within the medical school and residency curriculum.
The Impact of Using Incorrect Weights With the Multiple Membership Random Effects Model
Authors: Wolff Smith Lindsey J. , Beretvas S. Natasha
Published: May 2013

The multiple membership random effects model (MMREM) is used to appropriately model multiple membership data structures. Use of the MMREM requires selection of weights reflecting the hypothesized contribution of each level two unit (e.g., school) and their descriptors to the level one outcome. This study assessed the impact on MMREM parameter and residual estimates of the choice of weight pattern used. Parameter and residual estimates resulting from use of different weight patterns were compared using a real dataset and a small-scale simulation study. Under the conditions examined here, results indicated that choice of weight pattern did not greatly impact relative parameter bias nor level two residuals’ ranks. Limitations and directions for future research are discussed.
Cognitive control dysfunction and abnormal frontal cortex activation in stimulant drug users and their biological siblings
Authors: Smith D G , Jones P S , Bullmore E T , Robbins T W , Ersche K D
Published: May 2013

Cognitive and neural abnormalities are known to accompany chronic drug abuse, with impairments in cognition and changes in cortical structure seen in stimulant-dependent individuals. However, premorbid differences have also been observed in the brains and behavior of individuals at risk for substance abuse, before they develop dependence. Endophenotype research has emerged as a useful method for assessing preclinical traits that may be risk factors for pathology by studying patient populations and their undiagnosed first-degree relatives. This study used the color-word Stroop task to assess executive functioning in stimulant-dependent individuals, their unaffected biological siblings and unrelated healthy control volunteers using a functional magnetic resonance imaging paradigm. Both the stimulant-dependent and sibling participants demonstrated impairments in cognitive control and processing speed on the task, registering significantly longer response latencies. However, the two groups generated very different neural responses, with the sibling participants exhibiting a significant decrease in activation in the inferior frontal gyrus compared with both stimulant-dependent individuals and control participants. Both target groups also demonstrated a decrease in hemispheric laterality throughout the task, exhibiting a disproportionate increase in right hemispheric activation, which was associated with their behavioral inefficiencies. These findings not only suggest a possible risk factor for stimulant abuse of poor inhibitory control and cortical inefficiency but they also demonstrate possible adaptations in the brains of stimulant users.
Fluorophore Conjugates for Single Molecule Work
Authors: Ranasinghe Rohan T. , Klenerman David
Published: May 2013

Single molecule fluorescence spectroscopy (SMFS) has become an established biophysical technique since its first demonstration 35 years ago, along the way stimulating a revolution in the study of DNA sequence, structure and function. In this chapter we summarise the physical and chemical techniques underlying these advances, with emphasis on the selection of fluorophores for single molecule work and their conjugation to DNA. We then highlight a few key applications of SMFS including next generation sequencing technologies, the determination of DNA structures at nanometre resolution and the dissection of protein-DNA interactions one complex at a time.
Conventional and global maximum power point tracking techniques in photovoltaic applications: A review
Authors: Pallavee Bhatnagar A. , Nema B. R. K.
Published: May 2013

Maximum Power Point Tracking (MPPT) is a technique employed to extract maximum power available from a photovoltaic (PV) module under varying atmospheric conditions. It traces the PV operating voltage corresponding to the maximum power point (MPP) and operates the panel at MPP. However, if a PV array is partially shaded, the conventional MPPT techniques track local MPP and fail to track global MPP. Also, if modules with different optimal currents are connected in series—parallel local MPPs occur in the P-V curves and conventional MPPT techniques fail to search global maxima. A lot of literature is available on global MPPT techniques to increase overall system efficiency. The power conditioning unit should, therefore, be capable of searching global maximum power point also. This paper aims at presenting a number of conventional and global MPPT techniques; these methods are discussed in detail on the basis of certain performance parameters.
Real second order freeness and Haar orthogonal matrices
Authors: Mingo James A. , Popa Mihai
Published: May 2013

We demonstrate the asymptotic real second order freeness of Haar distributed orthogonal matrices and an independent ensemble of random matrices. Our main result states that if we have two independent ensembles of random matrices with a real second order limit distribution and one of them is invariant under conjugation by an orthogonal matrix, then the two ensembles are asymptotically real second order free. This captures the known examples of asymptotic real second order freeness introduced by Redelmeier.
Two-photon-induced singlet fission in rubrene single crystal
Authors: Ma Lin , Galstyan Gegham , Zhang Keke , Kloc Christian , Sun Handong , Soci Cesare , Michel-Beyerle Maria E. , Gurzadyan Gagik G.
Published: May 2013

The two-photon-induced singlet fission was observed in rubrene single crystal and studied by use of femtosecond pump-probe spectroscopy. The location of two-photon excited states was obtained from the nondegenerate two-photon absorption (TPA) spectrum. Time evolution of the two-photon-induced transient absorption spectra reveals the direct singlet fission from the two-photon excited states. The TPA absorption coefficient of rubrene single crystal is 52 cm/GW at 740 nm, as obtained from Z-scan measurements. Quantum chemical calculations based on time-dependent density functional theory support our experimental data.
Large coercivity and exchange bias in [Fe1−δ(FeO)δ]x(TiO2)1−x granular films
Authors: Cheng Y. H. , Zhang X. H. , Li L. Y. , Wang C. H. , Luo X. G. , Liu Hui , Wang W. H. , Zheng R. K.
Published: May 2013

[Fe1−δ(FeO)δ]x(TiO2)1−x (0≤δ≤0.91, 0.34≤x≤0.54) granular films were fabricated by magnetron sputtering. Large coercivity (HC = 10.5 kOe) and exchange-bias-field (HE = 6.5 kOe) at 5 K were found in the film with δ=0.84 and x = 0.48. AC susceptibility measurements exhibit a frequency (f) dependent peak Tf in the in-phase susceptibility curve. The fitting of the relation of Tf vs f with both the Vogel-Fulcher law and critical slowing down theory indicate that the evident enhancement of the HC and HE can be qualitatively ascribed to the existence of cluster-spin glass state. The results may help to deeply understand the origin of exchange bias and related effects.
Phonon transport in an initially twisted polyvinyl acetate nanofiber
Authors: Liangruksa Monrudee , Puri Ishwar K.
Published: May 2013

A reduction in phonon thermal conductivity enhances thermoelectric performance. One method to accomplish this is by applying mechanical stress to a nanostructure. We consider an initially twisted 20 nm polyvinyl acetate nanofiber undergoing torsion. Our analytical method uses the continuum approach of Mooney's model. Torsion modifies the phonon dispersion. Angles of twist between 45° and 70° reduce the averaged phonon group velocity and the phonon thermal conductivity but when these angles are increased further, this conductivity increases. This suggests a phonon engineering approach to tune the thermal conductivity of nanomaterials.
Faraday rotation in magnetically biased graphene at microwave frequencies
Authors: Sounas D. L. , Skulason H. S. , Nguyen H. V. , Guermoune A. , Siaj M. , Szkopek T. , Caloz C.
Published: May 2013

Faraday rotation is experimentally observed at microwave frequencies in a large-area graphene sheet biased with a static magnetic field, and interrogated by polarized fields in a hollow circular waveguide. A Faraday rotation of up to 1.5° and an isolation of more than 30 dB is observed, suggesting possible applications to graphene based isolators, circulators, and other non-reciprocal devices. An analytic model is developed for the scattering parameters of the measured structure. The model shows excellent agreement with the measurements and is used to extract the graphene conductivity, carrier density, and mobility.
Tailoring palladium nanocontacts by electromigration
Authors: Arzubiaga Libe , Golmar Federico , Llopis Roger , Casanova Fèlix , Hueso Luis E.
Published: May 2013

Electromigration is employed in nanoelectronics for transforming narrow metallic wires into electrodes separated by a few nanometers gap. In this work, we fabricate either nanoconstrictions or nanogap electrodes by performing electromigration in palladium nanowires. The device resistance and the cross section of the initial nanowires allow us to regulate the conditions for transforming deterministically each nanowire in a specific final device. The resulting samples show unique electrical transport characteristics and could be used in multiple nanoelectronics research applications, from ballistic transport to electrodes for single molecular devices.
Multiple current peaks in room-temperature atmospheric pressure homogenous dielectric barrier discharge plasma excited by high-voltage tunable nanosecond pulse in air
Authors: Yang De-Zheng , Wang Wen-Chun , Zhang Shuai , Tang Kai , Liu Zhi-jie , Wang Sen
Published: May 2013

Room temperature homogenous dielectric barrier discharge plasma with high instantaneous energy efficiency is acquired by using nanosecond pulse voltage with 20–200 ns tunable pulse width. Increasing the voltage pulse width can lead to the generation of regular and stable multiple current peaks in each discharge sequence. When the voltage pulse width is 200 ns, more than 5 organized current peaks can be observed under 26 kV peak voltage. Investigation also shows that the organized multiple current peaks only appear in homogenous discharge mode. When the discharge is filament mode, organized multiple current peaks are replaced by chaotic filament current peaks.
SnS thin film solar cells with Zn1−xMgxO buffer layers
Authors: Ikuno Takashi , Suzuki Ryo , Kitazumi Kosuke , Takahashi Naoko , Kato Naohiko , Higuchi Kazuo
Published: May 2013

The conduction band offset (CBO) of SnS as the light absorbing layer and Zn1−xMgxO as the buffer layer in SnS thin film solar cells has been optimized to improve the solar cell conversion efficiency. We controlled the CBO experimentally by varying the Mg content (x) of the Zn1−xMgxO layer. The optimum CBO value range for improved solar cell performance was determined to be from −0.1 to 0 eV. A SnS thin film solar cell sample with the optimum CBO value exhibited conversion efficiency of approximately 2.1%.
Lattice, band, and spin engineering in Zn1−xCoxO
Authors: Matsui Hiroaki , Tabata Hitoshi
Published: May 2013

This work was conducted to investigate lattice, band, and spin engineering of magnetic Zn1−xCoxO layers towards quantum barriers in ZnO. Lattice distortions by doping with Co ions caused a flat tetrahedron in the host, leading to an increase of spontaneous polarization in Zn1−xCoxO compared to ZnO based on the point-charge model. The band-gap energy increased linearly with the Co concentrations, which was very similar to the band-gap widening in Zn1−xMgxO derived from sp hybridization. The Co (3d) states were located in the mid-gap, which remained unchanged following changes in Co concentrations. Large magneto-optical effects were induced at the band edge due to sp-d exchange interactions. However, magneto-optical activity was reduced in heavily doping concentrations above x = 0.16 because of antiferromagnetic coupling between nearest-neighbor Co ions. The high magnetic activity at x = 0.10 is related to competition between the complex Co-related configurations, such as singles, pairs, open and closed triples, in Co-doped ZnO layers. Magnetic Zn1−xCoxO therefore has an effective layer composition for applications of quantum barriers.
Diffusion of carbon oxides in SiO2 during SiC oxidation: A first-principles study
Authors: Akiyama Toru , Nakamura Kohji , Ito Tomonori , Kageshima Hiroyuki , Uematsu Masashi
Published: May 2013

The diffusion mechanisms of CO and CO2 molecules in SiO2 during SiC oxidation are theoretically investigated by means of total-energy calculations within the density-functional theory. We find characteristic features of the stable structures of carbon oxides depending on polymorph of SiO2. The calculated formation energies and diffusion energy barriers of CO and CO2 in SiO2 also reveal that the CO2 can be a dominant species of product gas caused by SiC oxidation. On the basis of calculated results, we propose that the outward diffusion of carbon oxides as well as the reaction processes at SiO2/SiC interface is rate-limiting during SiC oxidation on the Si-face.
Nb nano superconducting quantum interference devices with high spin sensitivity for operation in magnetic fields up to 0.5 T
Authors: Wölbing R. , Nagel J. , Schwarz T. , Kieler O. , Weimann T. , Kohlmann J. , Zorin A. B. , Kemmler M. , Kleiner R. , Koelle D.
Published: May 2013

We investigate electric transport and noise properties of microstrip-type submicron direct current superconducting quantum interference devices (dc SQUIDs) based on Nb thin films and overdamped Josephson junctions with a HfTi barrier. The SQUIDs were designed for optimal spin sensitivity Sμ1/2 upon operation in intermediate magnetic fields B (tens of mT), applied perpendicular to the substrate plane. Our, so far, best SQUID can be continuously operated in fields up to B≈±50 mT with rms flux noise SΦ,w1/2≤250 nΦ0/Hz1/2 in the white noise regime and spin sensitivity Sμ1/2≤29 μB/Hz1/2. Furthermore, we demonstrate operation in B = 0.5 T with high sensitivity in flux SΦ,w1/2≈680 nΦ0/Hz1/2 and in electron spin Sμ1/2≈79 μB/Hz1/2. We discuss strategies to further improve the nanoSQUID performance.
Electromechanical responses of Cu strips
Authors: Zhao Guangfeng , Liu Ming , An Zhinan , Ren Yang , Liaw Peter K. , Yang Fuqian
Published: May 2013

Electrical-thermal-mechanical behavior of materials plays an important role in controlling the structural integrity of electromechanical structures of small volumes. The electromechanical response of Cu strips was studied by passing an electric current through the strips with electric current densities in the range of 12.34 to 29.60 kA/cm2. The passage of the electric current of high current densities introduced electrical-thermal-mechanical interactions, which caused grain growth and grain rotation in both the melted region and heat-affected zone. The electrothermal interactions led to the elastoplastic buckling of the Cu strips with the maximum deflection of the Cu strips increasing with the increase of the electric current density. The total strain is a quadratic function of the electric current density. There was a quasi-steady state in which the electric resistance of the Cu strips linearly increased with time before the occurrence of electric fusing. A power-law relation was used to describe the dependence of the time-to-failure (electric fusing) on the electric current density. For the region of relatively low current densities, the current exponent ranged from 17.9 to 44.6, and for the region of high current densities, the current exponent ranged from 2.5 to 5.2. The current exponent for relatively low current densities decreased with increasing the length of Cu strips, showing size-dependence. Finite element analyses were performed to analyze the current-induced deflection of a Cu strip. The simulation results showed that the maximum deflection for the electric current density larger than or equal to 5 kA/cm2 is a linear function of the current density in agreement with the experimental observation.
Strain effects on formation and migration energies of oxygen vacancy in perovskite ferroelectrics: A first-principles study
Authors: Yang Q. , Cao J. X. , Ma Y. , Zhou Y. C. , Jiang L. M. , Zhong X. L.
Published: May 2013

Oxygen vacancies (VO) and their migration and redistribution are believed to be the dominant factors resulting in the degradation of ferroelectrics. Thus, suppressing the formation and mobility of VO is quite crucial for the physical properties of ferroelectric materials. In this paper, the ab-biaxial strain effects on VO and their migration process in prototype perovskite ferroelectric BaTiO3 were studied by first principles total energy calculation. It is found that the formation energies for the two symmetrically inequivalent VO are enhanced under compressive strain. VO migration path between Vc (VO is located along the c-axis) and Vab (VO is located in the ab-plane) shows an “S” shape. The VO migration barrier between Vc and Vab is enhanced by the compressive strain while lowered by the tensile strain. These results suggest that the ferroelectricity degradation induced by VO and their migration can be effectively mitigated by applying compressive strain.
Electrical modeling of InSb PiN photodiode for avalanche operation
Authors: Abautret J. , Perez J. P. , Evirgen A. , Martinez F. , Christol P. , Fleury J. , Sik H. , Cluzel R. , Ferron A. , Rothman J.
Published: May 2013

Current density-voltage (J-V) characteristics at 77 K of InSb pin photodiodes, in dark condition and under illumination, were simulated in view to design an avalanche photodiode (APD). Theoretical J-V results were compared with experimental results, performed on InSb diode fabricated by molecular beam epitaxy, in order to validate the parameter values used for the modeling. Then, with the assumption of multiplication induced by the electrons, an optimized separate absorption and multiplication APD structure was defined by theoretically studying the absorber doping level and the multiplication layer thickness. Calculated gain value higher than 10 was achieved at V = −4.5 V. This result shows the potentiality of InSb material as APD device.
Dynamic micro-air-bubble drifted in a liquid core fiber Fabry-Pérot interferometer for directional fiber-optic level meter
Authors: Lee Cheng-Ling , Zheng Yang-Chen , Ma Chia-Lien , Chang Han-Jung , Lee Chung-Fen
Published: May 2013

We propose a dynamic, directional, and miniature fiber-optic level meter based on a micro-air-bubble drifted in a liquid-core fiber Fabry-Pérot interferometer. The proposed in-fiber level meter can detect the non-horizontal/horizontal state of an object/structure and also be able to discriminate the test structure inclining to the clockwise or counterclockwise directions by measuring the spectral responses of the proposed optical fiber device. Dynamic drifting of the micro air bubble in the tilted condition has been recorded which investigates the drifted directions correlated closely with the tilted directions in the fiber level meter.
A carbon nanotube based ammonia sensor on cotton textile
Authors: Han Jin-Woo , Kim Beomseok , Li Jing , Meyyappan M.
Published: May 2013

A single-wall carbon nanotube (CNT) based ammonia (NH3) sensor was implemented on a cotton yarn. Two types of sensors were fabricated: Au/sensing CNT/Au and conducting/sensing/conducting all CNT structures. Two perpendicular Au wires were designed to contact CNT-cotton yarn for metal-CNT sensor, whereas nanotubes were used for the electrode as well as sensing material for the all CNT sensor. The resistance shift of the CNT network upon NH3 was monitored in a chemiresistor approach. The CNT-cotton yarn sensors exhibited uniformity and repeatability. Furthermore, the sensors displayed good mechanical robustness against bending. The present approach can be utilized for low-cost smart textile applications.
Color-tunable upconversion luminescence of Yb3+, Er3+, and Tm3+ tri-doped ferroelectric BaTiO3 materials
Authors: Zhang Yang , Hao Jianhua
Published: May 2013

Tunable upconversion (UC) multicolor luminescence is observed from Yb3+, Er3+, and Tm3+ tri-doped ferroelectric BaTiO3 (BTO) materials. By control of dopant concentrations, the lanthanide-doped BTO powders are capable of generating various UC spectra and color tunability. A white-light emission is achieved through an optimal design. Strong UC luminescence is also observed in the lanthanide-doped BTO thin-films grown on Pt/TiO2/SiO2/Si substrate, which can retain well-defined hysteresis loops with a remnant polarization (2Pr) of 17.8 μC/cm2. These findings open the possibility of lanthanide-doped BTO as multifunctional materials, in which both luminescent and ferroelectric properties co-exist.
Terahertz transmission and sheet conductivity of randomly stacked multi-layer graphene
Authors: Baek I. H. , Ahn K. J. , Kang B. J. , Bae S. , Hong B. H. , Yeom D.-I. , Lee K. , Jeong Y. U. , Rotermund F.
Published: May 2013

We investigate transmission characteristics and sheet conductivity of mono- to multi-layer graphene deposited on quartz in the terahertz (THz) frequency region. The free carrier absorption and Fabry-Perot interference between graphene layers give rise to nonlinear decrease of THz transmission from 76.7% to 27% for mono- to 12-layer graphene. These phenomena are well explained with a modified theoretical model based on Drude conductivity. The optical sheet conductivity of multi-layer graphene, made by layer-by-layer random stacking of high-quality mono-layer graphene, at 1 THz exhibits two orders of magnitude higher values than the universal optical conductivity due to intraband transition of intrinsic graphene.
Holographic storage and multiplexing in azopolyester blends using low energy pulses down to 2 ms
Authors: Berges C. , Javakhishvili I. , Hvilsted S. , Sánchez-Somolinos C. , Alcalá R.
Published: May 2013

Three different blends containing side-chain azobenzene polyesters and poly(methyl methacrylate) homopolymers have been prepared for recording volume holographic polarization gratings using 488 nm light pulses. The final azo content in the blends has been decreased down to 0.2 wt. %, and their morphologies have been investigated by transmission electron microscopy. Stable and rewritable polarization gratings have been recorded, and 20 gratings have been multiplexed using 2 ms pulses of low energy (4 mJ/cm2). The equilibrium values of the diffraction efficiency were higher than 5 × 10−5.
Communication: A case where the hard/soft acid/base principle holds regardless of acid/base strength
Authors: Ayers Paul W. , Cárdenas Carlos
Published: May 2013

We show that the hard/soft acid/base principle holds when electron-transfer effects are dominant and the weaker acid and stronger base are harder than the other acidic and basic reagents. In this case the preference of strong acids for strong bases and weak acids for weak bases reinforces the preference of hard acids for hard bases and soft acids for soft bases.