bluuebunny/crossref_metadata_2025 huggingface dataset:
Epoch‐based likelihood models reveal no evidence for accelerated evolution of viviparity in squamate reptiles in response to cenozoic climate change
Authors: King Benedict , Lee Michael S. Y.
Published: April 2015

A broad scale analysis of the evolution of viviparity across nearly 4,000 species of squamates revealed that origins increase in frequency toward the present, raising the question of whether rates of change have accelerated. We here use simulations to show that the increased frequency is within the range expected given that the number of squamate lineages also increases with time. Novel, epoch‐based methods implemented in BEAST (which allow rates of discrete character evolution to vary across time‐slices) also give congruent results, with recent epochs having very similar rates to older epochs. Thus, contrary to expectations, there was no accelerated burst of origins of viviparity in response to global cooling during the Cenozoic or glacial cycles during the Plio‐Pleistocene. However, if one accepts the conventional view that viviparity is more likely to evolve than to be lost, and also the evidence here that viviparity has evolved with similar regularity throughout the last 200 Ma, then the absence of large, ancient clades of viviparous squamates (analogs to therian mammals) requires explanation. Viviparous squamate lineages might be more prone to extinction than are oviparous lineages, due to their prevalance at high elevations and latitudes and thus greater susceptibility to climate fluctuations. If so, the directional bias in character evolution would be offset by the bias in extinction rates. J. Exp. Zool. (Mol. Dev. Evol.) 324B: 525–531, 2015. © 2015 Wiley Periodicals, Inc.
The Post‐2015 Global Development Agenda: A Latin American Perspective
Authors: Comim Flavio
Published: April 2015

The paper briefly examines the literature that criticises the Millennium Development Goals (MDGs) from a Latin American perspective. It presents some key stylised facts of development from the contemporary history of the region. It focuses on three structural features of Latin American development, namely, inequality, conflict and low State capacity. Finally, it discusses the relevance and adequacy of some MDGs and targets based on the theoretical criticisms and empirical evidence examined earlier. It concludes by offering suggestions for the post‐2015 global development agenda. Copyright © 2015 John Wiley & Sons, Ltd.
Distinctive oncological features of stage IIIA colorectal cancer: Analysis of prognostic factors for selective adjuvant chemotherapy
Authors: Park Soo Yeun , Choi Gyu‐Seog , Park Jun Seok , Kim Hye Jin , Sakai Yoshiharu , Hasegawa Suguru , Watanabe Toshiaki , Kim Seon Hahn
Published: April 2015

Introduction

In the seventh TNM classification, stage IIIA includes tumors with early stage of bowel wall invasion and regional lymph node metastasis. We investigated the validity of the current TNM classification of patients with stage IIIA colorectal cancer and identified prognostic factors of them for ameliorating treatment strategies for them.

Methods

This study included the participation of four tertiary hospitals. A total of 4,236 patients with Stages I–IIIB colorectal cancer were analyzed. The primary end point was the 5‐year relapse‐free survival.

Results

The 5‐year relapse‐free survival of patients with stage IIIA disease was similar to that of patients with stage IIA. The 5‐year relapse‐free survival was 88.9% in the chemotherapy group (n = 152) and 82.3% in the no‐chemotherapy group (n = 36, P = 0.111). Tumor differentiation (moderate or poor) and venous invasion were independent prognostic factors of relapse‐free survival.

Conclusions

The relapse‐free survival of patients with stage IIIA tumors was similar to that of patients with stage IIA tumors, and the prognosis of stage IIIA tumors varied significantly by the tumor factors identified. These factors can be used to predict the risk of disease recurrence and to optimize the use of adjuvant chemotherapy. J. Surg. Oncol. 2015 111:882–890. © 2014 Wiley Periodicals, Inc.
The distance between breast cancer and the skin is associated with axillary nodal metastasis
Authors: Eom Yong Hwa , Kim Eun Jin , Chae Byung Joo , Song Byung Joo , Jung Sang Seol
Published: April 2015

Background and Objectives

More superficially located tumors may be more likely than deeper tumors to metastasize to the axillary nodes via the lymphatics. The aim of this study was to determine whether breast cancer distance from the skin affects axillary node metastasis, ipsilateral breast cancer recurrence, or recurrence‐free survival.

Materials and Methods

A total of 1,005 consecutive patients with breast cancer who underwent surgery between January 2003 and December 2009 were selected. The distance of the tumor from the skin was measured from the skin to the most anterior hypoechoic leading edge of the lesion.

Results

In total, 603 (68%) patients had no axillary nodal metastasis, and 288 (32%) had axillary nodal metastasis. A breast cancer distance from the skin <3 mm induced more axillary nodal metastasis (P = 0.039). However, no significant correlation was observed between breast cancer distance from the skin <3 mm and ipsilateral breast cancer recurrence (P = 0.788) or recurrence‐free survival (P = 0.353).

Conclusions

Breast cancers located closer to the skin had a higher incidence of axillary nodal metastasis. Therefore, tumor distance from the skin should be considered when evaluating a patient with breast cancer and considering the risk of nodal metastasis. J. Surg. Oncol. 2015 111:824–828. © 2014 Wiley Periodicals, Inc.
Negative ion gas‐phase chemistry of arenes
Authors: Danikiewicz Witold , Zimnicka Magdalena
Published: April 2015

Reactions of aromatic and heteroaromatic compounds involving anions are of great importance in organic synthesis. Some of these reactions have been studied in the gas phase and are occasionally mentioned in reviews devoted to gas‐phase negative ion chemistry, but no reviews exist that collect all existing information about these reactions. This work is intended to fill this gap. In the first part of this review, methods for generating arene anions in the gas phase and studying their physicochemical properties and fragmentation reactions are presented. The main topics in this part are as follows: processes in which gas‐phase arene anions are formed, measurements and calculations of the proton affinities of arene anions, proton exchange reactions, and fragmentation processes of substituted arene anions, especially phenide ions. The second part is devoted to gas‐phase reactions of arene anions. The most important of these are reactions with electrophiles such as carbonyl compounds and α,β‐unsaturated carbonyl and related compounds (Michael acceptors). Other reactions including oxidation of arene anions and halogenophilic reactions are also presented. In the last part of the review, reactions of electrophilic arenes with nucleophiles are discussed. The best known of these is the aromatic nucleophilic substitution (SNAr) reaction; however, other processes that lead to the substitution of a hydrogen atom in the aromatic ring are also very important. Aromatic substrates in these reactions are usually but not always nitroarenes bearing other substituents in the ring. The first step in these reactions is the formation of an anionic σ‐adduct, which, depending on the substituents in the aromatic ring and the structure of the attacking nucleophile, is either an intermediate or a transition state in the reaction path. In the present review, we attempted to collect the results of both experimental and computational studies of the aforementioned reactions conducted since the very beginning of gas‐phase negative ion chemistry. © 2015 Wiley Periodicals, Inc. Mass Spec Rev 35: 123–146, 2016.
Characteristics and Treatment of Anxiety Disorders in Parkinson's Disease
Authors: Dissanayaka Nadeeka N.W. , White Elizabeth , O'Sullivan John D. , Marsh Rodney , Silburn Peter A. , Copland David A. , Mellick George D. , Byrne Gerard J.
Published: April 2015

Background: Anxiety disorders are common in Parkinson's disease (PD) and are undertreated. The current study investigates demographic and PD‐specific factors associated with Diagnostic and Statistical Manual (DSM‐IV) anxiety disorders and subsyndromal anxiety in PD. It also examines the use of pharmacological and nonpharmacological treatments for anxiety in PD. Methods: Ninety nondemented PD patients completed a semistructured interview. Logistic regression models were constructed examining associations between several demographic, disease‐specific, and treatment factors, as well as both current syndromal, DSM‐IV anxiety disorders, and subsyndromal anxiety. Results: Associations were found between current DSM‐IV anxiety disorder, as well as female gender, younger age, more severe stages of PD, and poor activities of daily living. Subsyndromal anxiety was related to a younger onset age of PD. Relationships were also found between both anxiety groups and more complications of PD therapy, as well as higher depression scores. There were no associations between anxiety and levodopa equivalent daily dosage, motor disability, and cognition. In our sample, 57% of patients with current DSM‐IV anxiety disorders or subsyndromal anxiety were not currently treated with pharmacotherapy. Of those who currently received such treatment, 83% still experienced current anxiety disorders. Results suggest that anxiety is poorly recognized and treated in PD. Conclusions: Clinical trials investigating the efficacy of pharmacotherapy, tailored psychotherapy, and combination therapy primarily focusing on anxiety are much needed, with the aim of establishing novel targeted treatment protocols for the management of subtypes of anxiety disorders in PD.
An Open Innovation Decision Support System to Select a Biopharmaceutical R&D Portfolio
Authors: Lo Nigro Giovanna , Morreale Azzurra , Abbate Lorenzo
Published: April 2015

Drugs available in the market today, selected several years ago under very uncertain future scenario, have experienced a long and expensive process of research and development carried out following both a closed and an open innovation path. To support this critical selection process, we propose a Decision Support System, able to choose among different candidates the most promising drugs along their best development path. The Decision Support System, based on a real options portfolio optimization model, mapping tools, and what‐if rules as well, has been applied to a numerical example available in literature, and the research findings show interesting managerial and academic implications. Copyright © 2015 John Wiley & Sons, Ltd.
Number of active electrodes at time of staged tined lead interstim implant does not impact clinical outcomes
Authors: Gilleran Jason P. , Killinger Kim , Boura Judith , Peters Kenneth M.
Published: April 2015

Objectives

To determine: (1) if obtaining motor response on <4 tined lead electrodes at time of placement affects subjective and objective clinical outcome and (2) voltage requirements to elicit motor response at implant and first postoperative visit number based on number of responding electrodes.

Methods

We reviewed our prospective neuromodulation database to identify patients with unilateral S3 lead placement and motor response (bellows ± toe flexion) on stimulation of 1–4 electrodes, then grouped by number of active electrodes at lead placement. Stage 1 success, reoperation and reprogramming rates, mean voltage at implant and first postoperative visit, and Interstitial Cystitis Symptom/Problem Indices (ICSI‐PI) were analyzed using Pearson's Chi‐square, Fisher's exact, Kruskal–Wallis or Wilcoxon rank tests.

Results

Two hundred forty four patients met inclusion criteria, categorized into 1–2 (n = 25), 3 (n = 48), and 4 active electrodes (n = 171). There were no significant differences between groups in terms of age, indications for neuromodulation, or stage 1 success. At implant, patients with <4 active electrodes required higher mean voltages for motor responses (5.9, 4.9, and 3.9 volts for each group respectively; P < 0.0001). Mean voltages for sensory threshold at first postoperative programming were 1.5 ± 1.5, 0.9 ± 1.0, and 0.8 ± 1.0, respectively (P = 0.08). Overall reoperation rates, and reprogramming sessions at 24 months did not differ (P = 0.72 and P = 0.50). ICSI‐PI scores improved similarly in all groups.

Conclusions

Motor response on four electrodes is not necessary for successful stage 1 trial. Despite higher voltage requirements in those with <4 active electrodes at implant, this difference was not observed at initial postoperative programming. Neurourol. Urodynam. 35:625–629, 2016. © 2015 Wiley Periodicals, Inc.
Uncovering the genomic heterogeneity of multifocal breast cancer
Authors: Desmedt Christine , Fumagalli Debora , Pietri Elisabetta , Zoppoli Gabriele , Brown David , Nik‐Zainal Serena , Gundem Gunes , Rothé Françoise , Majjaj Samira , Garuti Anna , Carminati Enrico , Loi Sherene , Van Brussel Thomas , Boeckx Bram , Maetens Marion , Mudie Laura , Vincent Delphine , Kheddoumi Naima , Serra Luigi , Massa Ilaria , Ballestrero Alberto , Amadori Dino , Salgado Roberto , de Wind Alexandre , Lambrechts Diether , Piccart Martine , Larsimont Denis , Campbell Peter J , Sotiriou Christos
Published: April 2015

Multifocal breast cancer (MFBC), defined as multiple synchronous unilateral lesions of invasive breast cancer, is relatively frequent and has been associated with more aggressive features than unifocal cancer. Here, we aimed to investigate the genomic heterogeneity between MFBC lesions sharing similar histopathological parameters. Characterization of different lesions from 36 patients with ductal MFBC involved the identification of non‐silent coding mutations in 360 protein‐coding genes (171 tumour and 36 matched normal samples). We selected only patients with lesions presenting the same grade, ER, and HER2 status. Mutations were classified as ‘oncogenic’ in the case of recurrent substitutions reported in COSMIC or truncating mutations affecting tumour suppressor genes. All mutations identified in a given patient were further interrogated in all samples from that patient through deep resequencing using an orthogonal platform. Whole‐genome rearrangement screen was further conducted in 8/36 patients. Twenty‐four patients (67%) had substitutions/indels shared by all their lesions, of which 11 carried the same mutations in all lesions, and 13 had lesions with both common and private mutations. Three‐quarters of those 24 patients shared oncogenic variants. The remaining 12 patients (33%) did not share any substitution/indels, with inter‐lesion heterogeneity observed for oncogenic mutation(s) in genes such as PIK3CA, TP53, GATA3, and PTEN. Genomically heterogeneous lesions tended to be further apart in the mammary gland than homogeneous lesions. Genome‐wide analyses of a limited number of patients identified a common somatic background in all studied MFBCs, including those with no mutation in common between the lesions. To conclude, as the number of molecular targeted therapies increases and trials driven by genomic screening are ongoing, our findings highlight the presence of genomic inter‐lesion heterogeneity in one‐third, despite similar pathological features. This implies that deeper molecular characterization of all MFBC lesions is warranted for the adequate management of those cancers. © 2015 The Authors. Pathological Society of Great Britain and Ireland.
Incorporation of dried blood alpha fetoprotein into traditional first trimester Down syndrome screening service
Authors: Carmichael Jonathan , Krantz David , Liu Hsiao‐Pin , Janik David , Hallahan Terrence
Published: April 2015

Objective

The aim of this study was to determine whether incorporation of dried blood alpha fetoprotein (AFP) into first trimester screening using the biochemical markers free Beta human chorionic gonadotropin (hCG) and pregnancy‐associated plasma protein A (PAPP‐A) can improve screening performance.

Methods

A retrospective study of 34 Down syndrome and 1185 unaffected dried blood specimens. First trimester dried blood AFP was performed using in‐house immunofluorometric time‐resolved assay. False positive and detection rates were determined from modeling.

Results

The multiple of the median in Down syndrome cases was 0.73. At a fixed 5% false positive rate, incorporating AFP into a free Beta hCG, PAPP‐A, and nuchal translucency protocol adds 2% detection resulting in detection rates of 92% to 94% depending on the gestational age of the blood draw. At a fixed 90% detection rate, AFP reduced the false positive rate by 1.0 to 1.6 percentage points depending on gestational age. Using a cutoff of 1/1000, the combination of free beta hCG, PAPP‐A, AFP, and nuchal translucency achieved a detection rate of 96% with a false positive rate of 8.4% to 9.9%. Adding in nasal bone increased detection to 98% while reducing false positive rates to 4.1% to 4.7%.

Conclusion

Inclusion of dried blood AFP into traditional first trimester screening improves detection while optimizing contingent protocols so that cell‐free fetal DNA testing may be offered in a more cost effective manner. © 2015 The Authors. Prenatal Diagnosis published by John Wiley & Sons Ltd.
Assessing the treatment effect in a randomized controlled trial with extensive non‐adherence: the EVOLVE trial
Authors: Kubo Yumi , Sterling Lulu Ren , Parfrey Patrick S , Gill Karminder , Mahaffey Kenneth W , Gioni Ioanna , Trotman Marie‐Louise , Dehmel Bastian , Chertow Glenn M
Published: April 2015

Intention‐to‐treat (ITT) analysis is widely used to establish efficacy in randomized clinical trials. However, in a long‐term outcomes study where non‐adherence to study drug is substantial, the on‐treatment effect of the study drug may be underestimated using the ITT analysis. The analyses presented herein are from the EVOLVE trial, a double‐blind, placebo‐controlled, event‐driven cardiovascular outcomes study conducted to assess whether a treatment regimen including cinacalcet compared with placebo in addition to other conventional therapies reduces the risk of mortality and major cardiovascular events in patients receiving hemodialysis with secondary hyperparathyroidism. Pre‐specified sensitivity analyses were performed to assess the impact of non‐adherence on the estimated effect of cinacalcet. These analyses included lag‐censoring, inverse probability of censoring weights (IPCW), rank preserving structural failure time model (RPSFTM) and iterative parameter estimation (IPE). The relative hazard (cinacalcet versus placebo) of mortality and major cardiovascular events was 0.93 (95% confidence interval 0.85, 1.02) using the ITT analysis; 0.85 (0.76, 0.95) using lag‐censoring analysis; 0.81 (0.70, 0.92) using IPCW; 0.85 (0.66, 1.04) using RPSFTM and 0.85 (0.75, 0.96) using IPE. These analyses, while not providing definitive evidence, suggest that the intervention may have an effect while subjects are receiving treatment. The ITT method remains the established method to evaluate efficacy of a new treatment; however, additional analyses should be considered to assess the on‐treatment effect when substantial non‐adherence to study drug is expected or observed. Copyright © 2015 John Wiley & Sons, Ltd.
Positing, fitting, and selecting regression models for pooled biomarker data
Authors: Mitchell Emily M. , Lyles Robert H. , Schisterman Enrique F.
Published: April 2015

Pooling biospecimens prior to performing lab assays can help reduce lab costs, preserve specimens, and reduce information loss when subject to a limit of detection. Because many biomarkers measured in epidemiological studies are positive and right‐skewed, proper analysis of pooled specimens requires special methods. In this paper, we develop and compare parametric regression models for skewed outcome data subject to pooling, including a novel parameterization of the gamma distribution that takes full advantage of the gamma summation property. We also develop a Monte Carlo approximation of Akaike's Information Criterion applied to pooled data in order to guide model selection. Simulation studies and analysis of motivating data from the Collaborative Perinatal Project suggest that using Akaike's Information Criterion to select the best parametric model can help ensure valid inference and promote estimate precision. Copyright © 2015 John Wiley & Sons, Ltd.
Manager Perspectives on Embedding Workplace Spirituality into the Business Curriculum: Bridging the Gap
Authors: Crossman Joanna
Published: April 2015

The purpose of this article is to share findings from an Australian qualitative study (n = 40) about the perspectives of managers and professionals around embedding workplace spirituality into the business curriculum. Academics are now publishing work that addresses workplace spirituality in the business curriculum, but few studies exist that focus on the perspectives of managers and professionals in the field. This article seeks to bridge that gap. Analysis revealed that managers as participants constructed rationales focusing on why workplace spirituality should or should not be addressed in the business curriculum and issues about how it might occur. Some of the perceived complexities of embedding workplace spirituality into public university programs were also identified. The findings of the paper would be particularly relevant to business schools considering the inclusion of workplace spirituality into their curriculum and structuring discussions to incorporate stakeholder perspectives from the business community. © 2015 Wiley Periodicals, Inc.
Parabolic limit with differential constraints of first-order quasilinear hyperbolic systems
Authors: Peng Yue-Jun , Wasiolek Victor
Published: April 2015

The goal of this work is to provide a general framework to study singular limits of initial-value problems for first-order quasilinear hyperbolic systems with stiff source terms in several space variables. We propose structural stability conditions of the problem and construct an approximate solution by a formal asymptotic expansion with initial layer corrections. In general, the equations defining the approximate solution may come together with differential constraints, and so far there are no results for the existence of solutions. Therefore, sufficient conditions are shown so that these equations are parabolic without differential constraint. We justify rigorously the validity of the asymptotic expansion on a time interval independent of the parameter, in the case of the existence of approximate solutions. Applications of the result include Euler equations with damping and an Euler–Maxwell system with relaxation. The latter system was considered in [27,9] which contain ideas used in the present paper.
Negative regulation of hepatitis B virus replication by forkhead box protein A in human hepatoma cells
Authors: Okumura Nobuaki , Ikeda Masanori , Satoh Shinya , Dansako Hiromichi , Sugiyama Masaya , Mizokami Masashi , Kato Nobuyuki
Published: April 2015

Hepatitis B virus (HBV) replication is controlled by liver‐enriched transcriptional factors, including forkhead box protein A (FOXA) members. Here, we found that FOXA members are directly and indirectly involved in HBV replication in human hepatic cells. HBV replication was elevated in HuH‐7 treated with individual FOXA members‐specific siRNA. Reciprocally, the downregulation of HBV replication was observed in FOXA‐induced HuH‐7. However, the mechanism of downregulation is different among FOXA members at the level of HBV RNA transcription, such as precore/pg RNA and 2.1 kb RNA. In addition, FOXA1 and FOXA2 suppressed nuclear hormone receptors, such as HNF4α, that are related to HBV replication.
Comprehensive analysis of microRNA expression profile in malignant glioma tissues
Authors: Piwecka Monika , Rolle Katarzyna , Belter Agnieszka , Barciszewska Anna Maria , Żywicki Marek , Michalak Marcin , Nowak Stanisław , Naskręt-Barciszewska Mirosława Z. , Barciszewski Jan
Published: April 2015

Malignant gliomas represent the most devastating group of brain tumors in adults, among which glioblastoma multiforme (GBM) exhibits the highest malignancy rate. Despite combined modality treatment, GBM recurs and is invariably fatal. A further insight into the molecular background of gliomagenesis is required to improve patient outcomes. The primary aim of this study was to gain broad information on the miRNA expression pattern in malignant gliomas, mainly GBM. We investigated the global miRNA profile of malignant glioma tissues with miRNA microarrays, deep sequencing and meta‐analysis. We selected miRNAs that were most frequently deregulated in glioblastoma tissues, as well as in peritumoral areas, in comparison with normal human brain. We identified candidate miRNAs associated with the progression from glioma grade III to glioma grade IV. The meta‐analysis of miRNA profiling studies in GBM tissues summarizes the past and recent advances in the investigation of the miRNA signature in GBM versus noncancerous human brain and provides a comprehensive overview. We propose a list of 35 miRNAs whose expression is most frequently deregulated in GBM patients and of 30 miRNA candidates recognized as novel GBM biomarkers.
Rolf Meissner (1925–2014)
Authors: Rabbel Wolfgang
Published: April 2015

Rolf Meissner was one of the most influential Earth scientists in crustal and lithospheric research. He passed away on 4 June 2014, shortly before his 89th birthday.
Fischer and Geballe Receive 2014 Mineral and Rock Physics Graduate Research Awards
Authors:   AGU
Published: April 2015

Rebecca Fischer and Zack Geballe have been awarded the 2014 Mineral and Rock Physics Graduate Research Award. This award is given to one or more promising young scientists in recognition of outstanding contributions achieved during their Ph.D. research.
Unprecedented one-pot synthesis of an unsymmetrical cisplatin-based Pt(iv)–acetamidato complex
Authors: Pelosi Giorgio , Ravera Mauro , Gabano Elisabetta , Fregonese Federico , Osella Domenico
Published: April 2015

We describe herein a novel Pt(iv)–acetamidato complex as a result of the one-pot reaction between cisplatin and the highly reactive peroxyacetimidic acid generated in situ.
The effect of output-input isolation on the scaling and energy consumption of all-spin logic devices
Authors: Hu Jiaxi , Haratipour Nazila , Koester Steven J.
Published: April 2015

All-spin logic (ASL) is a novel approach for digital logic applications wherein spin is used as the state variable instead of charge. One of the challenges in realizing a practical ASL system is the need to ensure non-reciprocity, meaning the information flows from input to output, not vice versa. One approach described previously, is to introduce an asymmetric ground contact, and while this approach was shown to be effective, it remains unclear as to the optimal approach for achieving non-reciprocity in ASL. In this study, we quantitatively analyze techniques to achieve non-reciprocity in ASL devices, and we specifically compare the effect of using asymmetric ground position and dipole-coupled output/input isolation. For this analysis, we simulate the switching dynamics of multiple-stage logic devices with FePt and FePd perpendicular magnetic anisotropy materials using a combination of a matrix-based spin circuit model coupled to the Landau–Lifshitz–Gilbert equation. The dipole field is included in this model and can act as both a desirable means of coupling magnets and a source of noise. The dynamic energy consumption has been calculated for these schemes, as a function of input/output magnet separation, and the results show that using a scheme that electrically isolates logic stages produces superior non-reciprocity, thus allowing both improved scaling and reduced energy consumption.
A four-probe thermal transport measurement method for nanostructures
Authors: Kim Jaehyun , Ou Eric , Sellan Daniel P. , Shi Li
Published: April 2015

Several experimental techniques reported in recent years have enabled the measurement of thermal transport properties of nanostructures. However, eliminating the contact thermal resistance error from the measurement results has remained a critical challenge. Here, we report a different four-probe measurement method that can separately obtain both the intrinsic thermal conductance and the contact thermal resistance of individual nanostructures. The measurement device consists of four microfabricated, suspended metal lines that act as resistive heaters and thermometers, across which the nanostructure sample is assembled. The method takes advantage of the variation in the heat flow along the suspended nanostructure and across its contacts to the four suspended heater and thermometer lines, and uses sixteen sets of temperature and heat flow measurements to obtain nine of the thermal resistances in the measurement device and the nanostructure sample, including the intrinsic thermal resistance and the two contact thermal resistances to the middle suspended segment of the nanostructure. Two single crystalline Si nanowires with different cross sections are measured in this work to demonstrate the effectiveness of the method. This four-probe thermal transport measurement method can lead to future discoveries of unique size-dependent thermal transport phenomena in nanostructures and low-dimensional materials, in addition to providing reliable experimental data for calibrating theoretical models.
Deformation dynamics of double emulsion droplet under shear
Authors: Chen Yongping , Liu Xiangdong , Zhao Yuanjin
Published: April 2015

We combine experimental observations with numerical simulations to explore the deformation dynamics of double emulsion droplet under shear. Two types of transient deformation topologies are identified via the respective underlying physical mechanisms. Especially, we demonstrate that the inner droplet can enhance the retracting of integral droplet, which leads to more intense transient deformation oscillations of double emulsion droplet than those of single-phase one. We further provide a regime diagram to quantitatively recognize the respective regime of these two transient deformation topologies, depending on the capillary number and radius ratio of inner droplet to the outer one.
The development of a room temperature electron cyclotron resonance ion source (Lanzhou electron cyclotron resonance ion source No. 4) with evaporative cooling technology at Institute of Modern Physics
Authors: Lu W. , Sun L. T. , Qian C. , Guo J. W. , Fang X. , Feng Y. C. , Yang Y. , Ma H. Y. , Zhang X. Z. , Ma B. H. , Xiong B. , Guo S. Q. , Ruan L. , Zhao H. W.
Published: April 2015

LECR4 (Lanzhou electron cyclotron resonance ion source No. 4) has been successfully constructed at IMP and has also been connected with the Low Energy Beam Transport (LEBT) and Radio Frequency Quadrupole (RFQ) systems. These source magnet coils are cooled through evaporative cooling technology, which is the first attempt with an ECR ion source in the world. The maximum mirror field is 2.5 T (with iron plug) and the effective plasma chamber volume is 1.2 l. It was designed to be operated at 18 GHz and aimed to produce intense multiple charge state heavy ion beams for the linear injector project SSC-Linac at IMP. In February 2014, the first analyzed beam at 18 GHz was extracted. During about three months’ commissioning, some outstanding results have been achieved, such as 1.97 emA of O6+, 1.7 emA of Ar8+, 1.07 emA of Ar9+, and 118 euA of Bi28+. The source has also successfully delivered O5+ and Ar8+ ion beams for RFQ commissioning in April 2014. This paper will give a brief overview of the design of LECR4. Then, the latest results of this source at 18 GHz will be presented.
Tailoring ergodicity through selective A-site doping in the Bi1/2Na1/2TiO3–Bi1/2K1/2TiO3 system
Authors: Acosta Matias , Liu Na , Deluca Marco , Heidt Sabrina , Ringl Ines , Dietz Christian , Stark Robert W. , Jo Wook
Published: April 2015

The morphotropic phase boundary composition Bi1/2Na1/2TiO3-20 mol. % Bi1/2K1/2TiO3 was chosen as initial material to do selective A-site aliovalent doping replacing Na and K by 1 at. % La, respectively. The materials were studied macroscopically by measuring dielectric and electromechanical properties. The Na-replaced material has a lower freezing temperature Tfr, lower remanent polarization and remanent strain, and thus a higher degree of ergodicity than the K-replaced material. These results are contrasted with local poling experiments and hysteresis loops obtained from piezoresponse force microscopy. The faster relaxation of the tip-induced local polarization and the lower remanent state in bias-on and -off loops confirm the higher degree of ergodicity of the Na-replaced material. The difference in functional properties is attributed to small variations in chemical pressure achieved through selective doping. Raman results support this working hypothesis.
Temperature dependence of the electronic transitions in BiFeO3 thin film studied by spectroscopic ellipsometry
Authors: Kang T. D. , Jeon B. C. , Moon S. J.
Published: April 2015

The temperature dependence of the electronic response of BiFeO3 thin film grown on a SrTiO3 substrate is investigated using spectroscopic ellipsometry. By analyzing the pseudodielectric function, we identify two d-d crystal field transitions of Fe3+ ions in the energy region between 1 and 2 eV. The d-d transitions show abnormal temperature dependence that cannot be attributed to conventional electron-phonon interactions. The origin of the abnormal temperature dependence is discussed in terms of spin-charge coupling. The temperature dependence of the charge transfer transitions located above 2.5 eV is characterized by standard critical point model analysis of the 2nd derivatives of the dielectric function. This analysis provides detailed information of the critical point parameters for charge transfer transitions.
Interplay of chemical expansion, Yb valence, and low temperature thermoelectricity in the YbCu2Si2−xGex solid solution
Authors: Lehr Gloria J. , Morelli Donald T.
Published: April 2015

YbCu2Si2 is a promising low temperature thermoelectric material because of the large broad peak in the Seebeck coefficient near 100 K combined with a low electrical resistivity. This behavior is thought to arise from fluctuating, or intermediate, valence effects due to partial occupation of Yb 4f energy states near the Fermi level. Previous studies of the magnetic properties under pressure have demonstrated that the average Yb valence is sensitive to the contraction of unit cell volume. By forming a solid solution of YbCu2Si2 with YbCu2Ge2, an isostructural compound with a larger unit cell volume, here we examine the subtle effects of lattice expansion on the transport properties and average Yb valence. We observe a shift in the peak of the Seebeck coefficient towards higher temperatures, as well as an enhanced power factor in the solid solutions. At the same time, a reduction in thermal conductivity due to alloy scattering enhances the thermoelectric figure of merit. Chemical pressure effects may thus be utilized to control and optimize the thermoelectric properties of these alloys in the cryogenic temperature range.
Metal thickness dependence on spin wave propagation in magnonic crystal using yttrium iron garnet
Authors: Kanazawa Naoki , Goto Taichi , Hoong Jet Wei , Buyandalai Altansargai , Takagi Hiroyuki , Inoue Mitsuteru
Published: April 2015

Magnonic crystals (MCs) are key components for spin wave manipulation. MCs realized with periodically metallized surfaces have an advantage in ease of the fabrication, but the effect of the metal thickness has not been studied well. In this work, the metal thickness dependence on the transmission spectra of localized mode spin waves was investigated. The metal thickness over half of the skin depth was necessary to prevent strong attenuation of spin waves.
Reliability of unstable periodic orbit based control strategies in biological systems
Authors: Mishra Nagender , Hasse Maria , Biswal B. , Singh Harinder P.
Published: April 2015

Presence of recurrent and statistically significant unstable periodic orbits (UPOs) in time series obtained from biological systems is now routinely used as evidence for low dimensional chaos. Extracting accurate dynamical information from the detected UPO trajectories is vital for successful control strategies that either aim to stabilize the system near the fixed point or steer the system away from the periodic orbits. A hybrid UPO detection method from return maps that combines topological recurrence criterion, matrix fit algorithm, and stringent criterion for fixed point location gives accurate and statistically significant UPOs even in the presence of significant noise. Geometry of the return map, frequency of UPOs visiting the same trajectory, length of the data set, strength of the noise, and degree of nonstationarity affect the efficacy of the proposed method. Results suggest that establishing determinism from unambiguous UPO detection is often possible in short data sets with significant noise, but derived dynamical properties are rarely accurate and adequate for controlling the dynamics around these UPOs. A repeat chaos control experiment on epileptic hippocampal slices through more stringent control strategy and adaptive UPO tracking is reinterpreted in this context through simulation of similar control experiments on an analogous but stochastic computer model of epileptic brain slices. Reproduction of equivalent results suggests that far more stringent criteria are needed for linking apparent success of control in such experiments with possible determinism in the underlying dynamics.
Elevator mode convection in flows with strong magnetic fields
Authors: Liu Li , Zikanov Oleg
Published: April 2015

Instability modes in the form of axially uniform vertical jets, also called “elevator modes,” are known to be the solutions of thermal convection problems for vertically unbounded systems. Typically, their relevance to the actual flow state is limited by three-dimensional breakdown caused by rapid growth of secondary instabilities. We consider a flow of a liquid metal in a vertical duct with a heated wall and strong transverse magnetic field and find elevator modes that are stable and, thus, not just relevant, but a dominant feature of the flow. We then explore the hypothesis suggested by recent experimental data that an analogous instability to modes of slow axial variation develops in finite-length ducts, where it causes large-amplitude fluctuations of temperature. The implications for liquid metal blankets for tokamak fusion reactors that potentially invalidate some of the currently pursued design concepts are discussed.
Experimental and theoretical determination of the plasmonic responses and shape distribution of colloidal metallic nanoparticles
Authors: Resano-Garcia A. , Battie Y. , En Naciri A. , Akil S. , Chaoui N.
Published: April 2015

The optical properties of gold and silver nanoparticles (NPs) dispersed in water and distributed in shape are investigated by introducing a shape distributed effective medium theory (SDEMT). This model takes into account the variation of depolarization parameter induced by a NP shape distribution. Simulations show that the shape distribution induces an inhomogeneous broadening and a decrease of the amplitude of the plasmon band. The number of plasmon bands and their positions depend on both the mean value of depolarization parameter and the NP material. By fitting the measured absorption spectra with the SDEMT, we unambiguously demonstrate that the depolarization parameter distribution, i.e., the shape distribution of nanoparticles can be deduced from absorption spectra.
Enhanced power factor and high-pressure effects in (Bi,Sb)2(Te,Se)3 thermoelectrics
Authors: Ovsyannikov Sergey V. , Morozova Natalia V. , Korobeinikov Igor V. , Lukyanova Lidia N. , Manakov Andrey Y. , Likhacheva Anna Y. , Ancharov Alexey I. , Vokhmyanin Alexander P. , Berger Ivan F. , Usov Oleg A. , Kutasov Vsevolod A. , Kulbachinskii Vladimir A. , Okada Taku , Shchennikov Vladimir V.
Published: April 2015

We investigated the effects of applied high pressure on thermoelectric, electric, structural, and optical properties of single-crystalline thermoelectrics, Bi2Te3, BixSb2−xTe3 (x = 0.4, 0.5, 0.6), and Bi2Te2.73Se0.27 with the high thermoelectric performance. We established that moderate pressure of about 2–4 GPa can greatly enhance the thermoelectric power factor of all of them. X-ray diffraction and Raman studies on Bi2Te3 and Bi0.5Sb1.5Te3 found anomalies at similar pressures, indicating a link between crystal structure deformation and physical properties. We speculate about possible mechanisms of the power factor enhancement and suppose that pressure/stress tuning can be an effective tool for the optimization of the thermoelectric performance.
Kolmogorov’s hypotheses and global energy spectrum of turbulence
Authors: Liao Zi-Ju , Su Wei-Dong
Published: April 2015

We relate the justification of Kolmogorov’s hypotheses on the local isotropy and small-scale universality in real turbulent flows to an observed universality of basis independence for the global energy spectrum and energy flux of small-scale turbulence. To readily examine the small-scale universality, an approach is suggested that investigates the global energy spectrum in a general spectral space for which the nonlinear interscale interaction may not be Fourier-triadic. Specific verifications are performed based on direct numerical simulations of turbulence in a spherical geometry and reexaminations of several existing results for turbulent channel flows.
Coalescence-controlled and coalescence-free growth regimes during deposition of pulsed metal vapor fluxes on insulating surfaces
Authors: Lü B. , Münger E. P. , Sarakinos K.
Published: April 2015

The morphology and physical properties of thin films deposited by vapor condensation on solid surfaces are predominantly set by the processes of island nucleation, growth, and coalescence. When deposition is performed using pulsed vapor fluxes, three distinct nucleation regimes are known to exist depending on the temporal profile of the flux. These regimes can be accessed by tuning deposition conditions; however, their effect on film microstructure becomes marginal when coalescence sets in and erases morphological features obtained during nucleation. By preventing coalescence from being completed, these nucleation regimes can be used to control microstructure evolution and thus access a larger palette of film morphological features. Recently, we derived the quantitative criterion to stop coalescence during continuous metal vapor flux deposition on insulating surfaces—which typically yields 3-dimensional growth—by describing analytically the competition between island growth by atomic incorporation and the coalescence rate of islands [Lü et al., Appl. Phys. Lett. 105, 163107 (2014)]. Here, we develop the analytical framework for entering a coalescence-free growth regime for metal vapor deposition on insulating substrates using pulsed vapor fluxes, showing that there exist three distinct criteria for suppressing coalescence that correspond to the three nucleation regimes of pulsed vapor flux deposition. The theoretical framework developed herein is substantiated by kinetic Monte Carlo growth simulations. Our findings highlight the possibility of using atomistic nucleation theory for pulsed vapor deposition to control morphology of thin films beyond the point of island density saturation.
Thermal phonon transport in silicon nanowires and two-dimensional phononic crystal nanostructures
Authors: Nomura Masahiro , Nakagawa Junki , Kage Yuta , Maire Jeremie , Moser Dominik , Paul Oliver
Published: April 2015

Thermal phonon transport in silicon nanowires (Si NWs) and two-dimensional phononic crystal (2D PnC) nanostructures was investigated by measuring thermal conductivity using a micrometer-scale time-domain thermoreflectance. The impact of nanopatterning on thermal conductivity strongly depends on the geometry, specularity parameter, and thermal phonon mean free path (MFP) distribution. Thermal conductivities for 2D PnC nanostructures were found to be much lower than that for NWs with similar characteristic length and surface-to-volume ratio due to stronger phonon back scattering. In single-crystalline Si, PnC patterning has a stronger impact at 4 K than at room temperature due to a higher specularity parameter and a longer thermal phonon MFP. Nanowire patterning has a stronger impact in polycrystalline Si, where thermal phonon MFP distribution is biased longer by grain boundary scattering.
Fourfold symmetric planar Hall effect in epitaxial La1−xSrxCoO3 thin films
Authors: Cui W. Y. , Li P. , Bai H. L.
Published: April 2015

The effect of Sr concentration on the planar Hall effect (PHE) in epitaxial magnetic phase separated La1−xSrxCoO3 (0.07 ≤ x ≤ 0.60) thin films was studied systematically. It was found that crystalline anisotropy and spin-orbital coupling are the main contributions to the unexpected fourfold symmetric PHE. The uniaxial anisotropy field was given by Huni = 70 Oe and cubic anisotropic field Hcub = 143 Oe, respectively. The magnetic anisotropy was weakened by Sr doping, which corresponds with the disappearance of the fourfold symmetry in PHE with the increasing Sr concentration. The first principle calculations proved that the contribution of Co-d orbitals to the magnetic anisotropy strongly depends on the Sr concentration. eg−dx2−y2 and eg−d3z2−r2 orbitals play a dominant role in the magnetic anisotropy of the samples with x = 0.125, 0.25, while the t2g−dxy, dyz, dxz orbitals contribute mainly to the magnetic anisotropy of the samples with x = 0.375, 0.5, 0.625.
Pencil-trace on printed silver interdigitated electrodes for paper-based NO2 gas sensors
Authors: Zhang Jiankun , Huang Lei , Lin Youjie , Chen Lu , Zeng Ziyan , Shen Leo , Chen Qi , Shi Wangzhou
Published: April 2015

The pencil-drawn sensor is expected to enable a simple, low-cost, and reproducible paper-based sensor platform for widely deployed wireless environmental monitoring of NO2. Herein, we demonstrated a rapid prototyping of chemiresistor-type NO2 sensor by mechanical abrasion of an 8B pencil to form a stripe of uniform graphitic coating on printed silver interdigitated electrodes (IDEs). The Ag IDEs not only offer a low resistance but also provide the assembly of Ag nanoparticles into exfoliated graphene sheets for the paper-based NO2 gas sensors in order to realise much higher sensitivity and better reproducibility comparing with pencil-drawn sensors directly on weighing paper.
Amorphous indium-gallium-zinc-oxide as electron transport layer in organic photodetectors
Authors: Arora H. , Malinowski P. E. , Chasin A. , Cheyns D. , Steudel S. , Schols S. , Heremans P.
Published: April 2015

Amorphous indium-gallium-zinc-oxide (a-IGZO) is demonstrated as an electron transport layer (ETL) in a high-performance organic photodetector (OPD). Dark current in the range of 10 nA/cm2 at a bias voltage of −2 V and a high photoresponse in the visible spectrum were obtained in inverted OPDs with poly(3-hexylthiophene) and phenyl-C61-butyric acid methyl ester active layer. The best results were obtained for the optimum a-IGZO thickness of 7.5 nm with specific detectivity of 3 × 1012 Jones at the wavelength of 550 nm. The performance of the best OPD devices using a-IGZO was shown to be comparable to state-of-the-art devices based on TiOx as ETL, with higher rectification achieved in reverse bias. Yield and reproducibility were also enhanced with a-IGZO, facilitating fabrication of large area OPDs. Furthermore, easier integration with IGZO-based readout backplanes can be envisioned, where the channel material can be used as photodiode buffer layer after additional treatment.