bluuebunny/crossref_metadata_2025 huggingface dataset:
Room temperature ferroelectric and magnetic investigations and detailed phase analysis of Aurivillius phase Bi5Ti3Fe0.7Co0.3O15 thin films
Authors: Keeney Lynette , Kulkarni Santosh , Deepak Nitin , Schmidt Michael , Petkov Nikolay , Zhang Panfeng F. , Cavill Stuart , Roy Saibal , Pemble Martyn E. , Whatmore Roger W.
Published: September 2012

Aurivillius phase Bi5Ti3Fe0.7Co0.3O15 (BTF7C3O) thin films on α-quartz substrates were fabricated by a chemical solution deposition method and the room temperature ferroelectric and magnetic properties of this candidate multiferroic were compared with those of thin films of Mn3+ substituted, Bi5Ti3Fe0.7Mn0.3O15 (BTF7M3O). Vertical and lateral piezoresponse force microscopy (PFM) measurements of the films conclusively demonstrate that BTF7C3O and BTF7M3O thin films are piezoelectric and ferroelectric at room temperature, with the major polarization vector in the lateral plane of the films. No net magnetization was observed for the in-plane superconducting quantum interference device (SQUID) magnetometry measurements of BTF7M3O thin films. In contrast, SQUID measurements of the BTF7C3O films clearly demonstrated ferromagnetic behavior, with a remanent magnetization, Br, of 6.37 emu/cm3 (or 804 memu/g), remanent moment = 4.99 × 10−5 emu. The BTF7C3O films were scrutinized by x-ray diffraction, high resolution transmission electron microscopy, scanning transmission electron microscopy, and energy dispersive x-ray analysis mapping to assess the prospect of the observed multiferroic properties being intrinsic to the main phase. The results of extensive micro-structural phase analysis demonstrated that the BTF7C3O films comprised of a 3.95% Fe/Co-rich spinel phase, likely CoFe2 − xTixO4, which would account for the observed magnetic moment in the films. Additionally, x-ray magnetic circular dichroism photoemission electron microscopy (XMCD-PEEM) imaging confirmed that the majority of magnetic response arises from the Fe sites of Fe/Co-rich spinel phase inclusions. While the magnetic contribution from the main phase could not be determined by the XMCD-PEEM images, these data however imply that the Bi5Ti3Fe0.7Co0.3O15 thin films are likely not single phase multiferroics at room temperature. The PFM results presented demonstrate that the naturally 2D nanostructured Bi5Ti3Fe0.7Co0.3O15 phase is a novel ferroelectric and has potential commercial applications in high temperature piezoelectric and ferroelectric memory technologies. The implications for the conclusive demonstration of ferroelectric and ferromagnetic properties in single-phase materials of this type are discussed.
Ferroelectric domain morphology and structure in Li-doped (K,Na)NbO3 ceramics
Authors: Cho Jeong Ho , Yeom Na Ri , Kwon So Jung , Lee Young Jin , Jeong Young Hun , Chun Myoung Pyo , Nam Joong Hee , Paik Jong Hoo , Kim Byung Ik
Published: September 2012

We prepared Li0.02(K0.45Na0.55)0.98NbO3 (KNN) ceramics using a conventional solid-state sintering method and investigated the domain structure and morphology using a piezoresponse force microscope in these material systems. The abnormal grain consisted of nano-sized subgrains, which were an elementary unit of the domain formation, with a size of approximately 100 nm. They were self-assembled and grew along the 〈001〉o directions. In the orthorhombic KNN ceramics, the 90° domains were dominantly distributed and all wedges were 60° wedges. The polarization vectors and geometrical configurations were analyzed and suggested in the banded twins. The observation of angles between (010)o and (011)o showed that the large grains experienced severe stress resulting in the deformation of the unit cell configuration during the phase transition. The S-walls were preferred as 120° domain walls and were assigned to (1/0.27/1)c.
Direct determination of the effect of strain on domain morphology in ferroelectric superlattices with scanning probe microscopy
Authors: Kathan-Galipeau K. , Wu P. P. , Li Y. L. , Chen L. Q. , Soukiassian A. , Zhu Y. , Muller D. A. , Xi X. X. , Schlom D. G. , Bonnell D. A.
Published: September 2012

A variant of piezo force microscopy was used to characterize the effect of strain on polarization in [(BaTiO3)n/(SrTiO3)m]p superlattices. The measurements were compared to theoretical predictions based on phase-field calculations. When polarization is constrained to be perpendicular to the substrate, the measured polarization and domain morphology agree quantitatively with the predictions. This case allows the presence of an internal electric field in the thin film to be identified. The measured trend in piezoelectric response with strain state was in qualitative agreement with predictions, and the differences were consistent with the presence of internal electrical fields. Clear differences in domain morphology with strain were observed; and in some cases, the lateral anisotropic strain appeared to influence the domain morphology. The differences in magnitude and morphology were attributed to the internal electric fields and anisotropic strains.
Accessing intermediate ferroelectric switching regimes with time-resolved transmission electron microscopy
Authors: Winkler Christopher R. , Jablonski Michael L. , Damodaran Anoop R. , Jambunathan Karthik , Martin Lane W. , Taheri Mitra L.
Published: September 2012

BiFeO3 (BFO) is one of the most widely studied magneto-electric multiferroics. The magneto-electric coupling in BiFeO3, which allows for the control of the ferroelectric and magnetic domain structures via applied electric fields, can be used to incorporate BiFeO3 into novel spintronics devices and sensors. Before BiFeO3 can be integrated into such devices, however, a better understanding of the dynamics of ferroelectric switching, particularly in the vicinity of extended defects, is needed. We use in situ transmission electron microscopy (TEM) to investigate the response of ferroelectric domains within BiFeO3 thin films to applied electric fields at high temporal and spatial resolution. This technique is well suited to imaging the observed intermediate ferroelectric switching regimes, which occur on a time- and length-scale that are too fine to study via conventional scanning-probe techniques. Additionally, the spatial resolution of transmission electron microscopy allows for the direct study of the dynamics of domain nucleation and propagation in the presence of structural defects. In this article, we show how this high resolution technique captures transient ferroelectric structures forming during biasing, and how defects can both pin domains and act as a nucleation source. The observation of continuing domain coalescence over a range of times qualitatively agrees with the nucleation-limited-switching model proposed by Tagantsev et al. We demonstrate that our in situ transmission electron microscopy technique is well-suited to studying the dynamics of ferroelectric domains in BiFeO3 and other ferroelectric materials. These biasing experiments provide a real-time view of the complex dynamics of domain switching and complement scanning-probe techniques.
The road to hot electron photochemistry at surfaces: A personal recollection
Authors: Gadzuk J. W.
Published: September 2012

A very important part of contemporary fs-laser surface photochemistry (SPC) is based on a proposed mechanism in which a laser pulse incident upon an adsorbate-covered surface photoexcites substrate electrons which in turn inelastically scatter from atoms and molecules (chemists may call them “reactants”) in or on the surface. The present narrative outlines my own very personal SPC saga that began with early exposure to the wonders of and fascination with inelastic resonant electron scattering from gas phase atoms and molecules that dominated the Atomic and Electron Physics activities at NBS (now NIST) in 1968 when I arrived. How this lead to a fundamental understanding of important aspects of SPC is the focus of this essay.
One-electron contributions to the g-tensor for second-order Douglas–Kroll–Hess theory
Authors: Sandhoefer B. , Neese F.
Published: September 2012

The electric g-tensor is a central quantity for the interpretation of electron paramagnetic resonance spectra. In this paper, a detailed derivation of the 1-electron contributions to the g-tensor is presented in the framework of linear response theory and the second-order Douglas–Kroll–Hess (DKH) transformation. Importantly, the DKH transformation in the presence of a magnetic field is not unique. Whether or not the magnetic field is included in the required Foldy-Wouthuysen transformation, different transformation matrices and, consequently, Hamiltonians result. In this paper, a detailed comparison of both approaches is presented, paying particular attention to the mathematical properties of the resulting Hamiltonians. In contrast to previous studies that address the g-tensor in the framework of DKH theory, the resulting terms are compared to those of the conventional Pauli theory and are given a physical interpretation. Based on these mathematical and physical arguments, we establish that the proper DKH transformation for systems with constant magnetic fields is based on a gauge-invariant Foldy-Wouthuysen transformation, i.e., a Foldy-Wouthuysen transformation including the magnetic field. Calculations using density functional theory (DFT) are carried out on a set of heavy, diatomic molecules, and a set of transition-metal complexes. Based on these calculations, the performance of the relativistic calculation with and without inclusion of picture-change effects is compared. Additionally, the g-tensor is calculated for the Lanthanide dihydrides. Together with the results from the other two molecular test sets, these calculations serve to quantify the magnitude of picture-change effects and elucidate trends across the periodic table.
Application of discrete variable representation to planar ${\rm H}_2^+$H2+ in strong xuv laser fields
Authors: Ning Qi-Cheng , Peng Liang-You , Hou Xue-Feng , Xu Zhen , Gong Qihuang
Published: September 2012

We present an efficient and accurate grid method to study the strong field dynamics of planar \documentclass[12pt]{minimal}\begin{document}${\rm H}_2 ^+$\end{document}H2+ under Born-Oppenheimer approximation. After introducing the elliptical coordinates to the planar \documentclass[12pt]{minimal}\begin{document}${\rm H}_2 ^+$\end{document}H2+, we show that the Coulomb singularities at the nuclei can be successfully overcome so that both bound and continuum states can be accurately calculated by the method of separation of variables. The time-dependent Schrödinger equation (TDSE) can be accurately solved by a two-dimensional discrete variable representation (DVR) method, where the radial coordinate is discretized with the finite-element discrete variable representation for easy parallel computation and the angular coordinate with the trigonometric DVR which can describe the periodicity in this direction. The bound states energies can be accurately calculated by the imaginary time propagation of TDSE, which agree very well with those computed by the separation of variables. We apply the TDSE to study the ionization dynamics of the planar \documentclass[12pt]{minimal}\begin{document}${\rm H}_2 ^+$\end{document}H2+ by short extreme ultra-violet (xuv) pulses, in which case the differential momentum distributions from both the length and the velocity gauge agree very well with those calculated by the lowest order perturbation theory.
Asymptotics and numerics of a family of two-dimensional generalized surface quasi-geostrophic equations
Authors: Ohkitani Koji
Published: September 2012

We study the generalised 2D surface quasi-geostrophic (SQG) equation, where the active scalar is given by a fractional power α of Laplacian applied to the stream function. This includes the 2D SQG and Euler equations as special cases. Using Poincaré’s successive approximation to higher α-derivatives of the active scalar, we derive a variational equation for describing perturbations in the generalized SQG equation. In particular, in the limit α → 0, an asymptotic equation is derived on a stretched time variable τ = αt, which unifies equations in the family near α = 0. The successive approximation is also discussed at the other extreme of the 2D Euler limit α = 2–0. Numerical experiments are presented for both limits. We consider whether the solution behaves in a more singular fashion, with more effective nonlinearity, when α is increased. Two competing effects are identified: the regularizing effect of a fractional inverse Laplacian (control by conservation) and cancellation by symmetry (nonlinearity depletion). Near α = 0 (complete depletion), the solution behaves in a more singular fashion as α increases. Near α = 2 (maximal control by conservation), the solution behave in a more singular fashion, as α decreases, suggesting that there may be some α in [0, 2] at which the solution behaves in the most singular manner. We also present some numerical results of the family for α = 0.5, 1, and 1.5. On the original time t, the H1 norm of θ generally grows more rapidly with increasing α. However, on the new time τ, this order is reversed. On the other hand, contour patterns for different α appear to be similar at fixed τ, even though the norms are markedly different in magnitude. Finally, point-vortex systems for the generalized SQG family are discussed to shed light on the above problems of time scale.
The resistive bolometer for radiated power measurement on EAST
Authors: Duan Y. M. , Hu L. Q. , Mao S. T. , Chen K. Y. , Lin S. Y. ,   EAST Diagnostics Team
Published: September 2012

The resistive bolometer system has been successfully employed on experimental advanced superconducting tokamak for the first time to measure the radiated power of plasma. The bolometer detectors are based on 4 μm thick Pt absorbers deposited on 1.5 μm thick SiN membranes. The system consists of 3 cameras with a total of 48 channels. The detector and the system setup are described in detail. The detector calibration and typical measurement results are presented as well.
Controlling spatial distribution of thermal poling induced second-order optical nonlinearity with multilayered structures
Authors: An Hong-Lin , Fleming Simon
Published: September 2012

Fused silica plates with boron-doped silicate multilayered thin films are thermally poled to create second-order optical nonlinearity for nonlinear optical applications. Measurement results from second harmonic microscopy show that the spatial distribution of the induced nonlinearity peaks at the interfaces between different layers where there is an abrupt change in boron concentration. A simple model is suggested to simulate the nonlinearity-trapping effect at the interfaces. This nonlinearity-trapping effect is not restricted to interfaces with abrupt refractive index changes; results from silica plates with deposited multilayered pure silica thin films show that the interface between the silica substrate and the silica thin film also has the nonlinearity-trapping effect.
Degradation induced decrease of the radiative quantum efficiency in organic light-emitting diodes
Authors: Schmidt Tobias D. , Setz Daniel S. , Flämmich Michael , Scholz Bert J. , Jaeger Arndt , Diez Carola , Michaelis Dirk , Danz Norbert , Brütting Wolfgang
Published: September 2012

The efficiency decrease during electrical operation of organic light-emitting diodes is a crucial issue for both applied and fundamental research. In order to investigate degradation processes, we have performed an efficiency analysis for phosphorescent state-of-the-art devices in the pristine state and after an accelerated aging process at high current density resulting in a luminance drop to less than 60% of the initial value. This loss in efficiency can be explained by a decrease of the radiative quantum efficiency of the light-emitting guest/host system from 70% to 40%, while other factors determining the efficiency are not affected.
Temporal evolution of dielectric barrier discharge microplasma
Authors: Blajan Marius , Shimizu Kazuo
Published: September 2012

Analysis of dielectric barrier discharge microplasma at atmospheric pressure was carried out using emission spectroscopy and imaging techniques. Temporal evolution of the discharge and also its filamentary mode was observed for the discharge in 3% N2 in Ar at the microdischarge level. Light emission from microplasma observed with the fast intensified charge coupled device (ICCD) camera for imaging was correlated with the evolution of the discharge current. The highest intensity of light emission occurred at the peak of the discharge current. The evolution of the discharge showed streamer reaching cathode, cathode layer formation, cathode layer enhancement, and cathode layer decay. Measurements of the Ar I peak at 696.5 nm and N2 second positive band system (N2 SPS) peak at 337.1 nm with the ICCD camera and spectrometer at various times corresponding to the discharge current showed similar time evolution as observed with the ICCD camera for imaging.
Unusual lattice constant changes and tunable magnetic moment compensation in Mn50−xCo25Ga25+x alloys
Authors: Li G. J. , Liu E. K. , Zhang H. G. , Qian J. F. , Zhang H. W. , Chen J. L. , Wang W. H. , Wu G. H.
Published: September 2012

We report on unusual lattice parameter changes and tunable magnetic moment compensation in Mn50−xCo25Ga25+x (x = 0-25) Heusler alloys by substituting Ga for Mn. The observed lattice parameter first increases with increasing Ga content x, showing a maximum at x = 12.5, and then abnormally decreases due to the enhanced covalence effect between transition-metal and main-group atoms. Moreover, a tunable magnetic moment compensation was also observed due to the diversification in role of the main magnetic contributor when the structure varies from Hg2CuTi-type Mn2CoGa to Cu2MnAl-type CoMnGa2. These results provide an alternative way to simultaneously tune both the structural and magnetic properties of Heusler alloys, which is particularly important for developing flexible spintronics devices.
Size effect on the electron wind force for electromigration at the top metal-dielectric interface in nanoscale interconnects
Authors: Wu Zhuo-Jie , Ho Paul S.
Published: September 2012

We report a classical model on the size effect of the electron wind force on a metal atom at the metal-dielectric interface in nanoscale interconnects. The effect is expressed as a size factor S for the effective charge Z*e. It is found that the size factor decreases with scaling due to reduced electron drift momentum as a result of scattering at interfaces and grain boundaries. The electron wind force on the metal atoms at the top metal-dielectric interface is enhanced by the interface scattering. This force enhancement is partially mitigated by the grain boundary scattering.
Apodized focusing subwavelength grating couplers for suspended membrane waveguides
Authors: Cheng Zhenzhou , Chen Xia , Wong Chi Yan , Xu Ke , Tsang Hon Ki
Published: September 2012

We demonstrate an apodized focusing subwavelength grating (SWG) for suspended membrane waveguides on silicon-on-insulator. Finite-difference time-domain simulation predicts −1.7 dB coupling efficiency and a 3 dB bandwidth of ∼50 nm for the transverse-magnetic mode apodized SWG, which has 98% field overlap with propagation mode in the single mode fiber. A modified phase matching formula is proposed to design the focusing apodized SWG. Better than −3.0 dB coupling efficiency and a 3 dB optical bandwidth of ∼50 nm is demonstrated experimentally.
Conduction mechanisms of epitaxial EuTiO3 thin films
Authors: Zhao R. , Li W. W. , Chen L. , Meng Q. Q. , Yang J. , Wang H. , Wang Y. Q. , Tang R. J. , Yang H.
Published: September 2012

To investigate leakage current density versus electric field characteristics, epitaxial EuTiO3 thin films were deposited on (001) SrTiO3 substrates by pulsed laser deposition and were post-annealed in a reducing atmosphere. This investigation found that conduction mechanisms are strongly related to temperature and voltage polarity. It was determined that from 50 to 150 K, the dominant conduction mechanism was a space-charge-limited current under both negative and positive biases. From 200 to 300 K, the conduction mechanism shows Schottky emission and Fowler-Nordheim tunneling behaviors for the negative and positive biases, respectively. This work demonstrates that Eu3+ is one source of leakage current in EuTiO3 thin films.
Correlating surface segregation and microstructural evolution of electrochemically deposited copper
Authors: Rizzolo Michael , Novak Steve , Lifshin Eric , Dunn Kathleen A.
Published: September 2012

Electroplating bath additives become problematic when incorporated into electrochemically deposited copper as impurities. The surface segregation of these impurities during spontaneous microstructural transformation was monitored by secondary ion mass spectrometry and found to be no different than the surface chemistry of the non-transforming plated samples or even sputtered copper. The results show that microstructural transformation of electroplated copper progresses despite the presence of impurities, suggesting foreign constituents are not in fact responsible for grain boundary pinning in these films.
Use of laparoscopic intrauterine insemination associated with a simplified superovulation treatment for in vivo embryo production in sheep: a preliminary report
Authors: Forcada F. , Sánchez-Prieto L. , Casao A. , Palacín I. , Cebrián-Pérez J. A. , Muiño-Blanco T. , Abecia J. A.
Published: September 2012

This study evaluated the reproductive performance of sheep that were subjected to superovulatory treatment and intrauterine insemination with two different doses of semen. The main objective was to determine whether intrauterine insemination is associated with higher rates of embryo recovery than existing procedures. In the first experiment 30 Ojalada de Soria ewes were used at the end of their productive life and nine younger ewes of the same breed were used in Experiment 2. Synchronisation of oestrus was conducted with intravaginal sponges and the superovulation treatment consisted of an intramuscular injection of 210 IU pFSH and 500 IU eCG administered 24 h before sponge removal. After 48 h of sponge withdrawal, ewes were inseminated by laparoscopy. They were divided into two groups: low dose group (LD, 25 × 106 sperm; n = 14 Expt 1 and n = 5 Expt 2) and high dose group (HD, 100 × 106 sperm; n = 14 Expt 1 and n = 4 Expt 2). Embryos were recovered 7 days after the onset of oestrus by laparotomy and uterine flushing. Two blood samples were collected in order to analyse cortisol, at sponge insertion and the day the embryos were recovered. The same protocol was repeated twice in Experiment 1, with an interval of 2 months between two consecutive treatments. Results show a significant effect of the number of recovery on ovulation rate (21.7 ± 2.2 v. 11.8 ± 1.1 corpora lutea for first and second recoveries, respectively), and number of structures recovered (11.4 ± 1.6 v. 5.2 ± 1.1, P < 0.01). Differences of embryo performance in the second recovery compared with the first one were more evident in the LD group compared with the HD group. In Experiment 2, results reflected a significant superiority of the HD group compared with the LD group, especially rate of fertilisation, which was 25% higher. Sheep producing non-fertilised embryos had higher cortisol levels at the time of flushing than those with embryos (P < 0.01). It is concluded that the use of simplified and consecutive superovulatory treatments associated with intrauterine insemination is a potential means of obtaining embryos, although the response seems to depend on donor sheep age. The use of a higher number of sperm cells per millilitre results in better outcomes in terms of embryos produced.
The In Vitro and In Vivo Antitumour Activities of Nitrosyl Ruthenium Amine Complexes
Authors: Osti Renata Z. , Serrano Fabiana A. , Paschoalin Thaysa , Massaoka Mariana H. S. , Travassos Luiz R. , Truzzi Daniela R. , Rodrigues Elaine G. , Franco Douglas W.
Published: September 2012

Ruthenium compounds of the type trans-[Ru(NO)(NH3)4(L)]X3, L = N-heterocyclic ligands, P(OEt)3, SO32–, X = BF4– or PF6–, or [Ru(NO)Hedta], were tested for antitumour activity in vitro against murine melanoma and human tumour cells. The ruthenium complexes induced DNA fragmentation and morphological alterations suggestive of necrotic tumour cell death. The calculated IC50 values were lower than 100 μM. Complexes for which L = isn or imN were partially effective in vivo in a syngeneic model of murine melanoma B16F10, increasing animal survival. In addition, the same ruthenium complexes effectively inhibited angiogenesis of HUVEC cells in vitro. The results suggest that these nitrosyl complexes are a promising platform to be explored for the development of novel antitumour agents.
Malawian secondary students’ beliefs about intelligence
Authors: Jones Brett D. , Rakes Lee , Landon Krista
Published: September 2012

Students who view intelligence as malleable tend to be more academically motivated and perform at higher levels than students who view it as a fixed trait. We examined the beliefs of students from Malawi because the culture and schooling process in this country is very different from some other areas of the world in which students’ views of intelligence have already been studied. Our research questions were: (1) How do Malawian students define intelligence? (2) To what extent do Malawian students view intelligence as malleable? (3) Are Malawian students’ definitions of intelligence and beliefs about the malleability of intelligence similar to those of students in more developed countries? We conducted a mixed methods study and surveyed 136 students attending a secondary school in Malawi using a 39‐item questionnaire. Students responded to questions about their intelligence beliefs on open‐ and closed‐ended items. Our results showed that Malawian students believe that an intelligent student exhibits a variety of behaviors, including studying, working hard, reading, performing well on exams and in class, answering and asking questions, paying attention, and demonstrating good behavior. Most students believe that intelligence is malleable and provided responses that indicated that students can become more intelligent through effort. When compared to the findings of other studies, the present results suggest that the Malawian students who remain in secondary school have definitions of intelligence and beliefs about the malleability of intelligence that are similar to those of students in more developed countries, such as the US and Germany. In fact, it appears that Malawian secondary students have even higher malleable beliefs than American and German students. Finally, some of the measures that have been found to produce scores that are reliable and valid in other populations do not produce scores that are as reliable when used with Malawian students.
Demonstration of Blue Crab Culture in Inland Low-Salinity Waters of West Alabama
Authors: Roy Luke A , Whitis Gregory N , Walton William C
Published: September 2012

The decline in natural stocks of blue crabs Callinectes sapidus in U.S. coastal waters has created more interest in the aquaculture of this species. The 2010 Deepwater Horizon oil spill threatened the health of blue crab populations in the Gulf of Mexico and spurred interest in alternative sources of blue crab harvest. Inland low-salinity waters (ILSW) of west Alabama have a proven potential for the culture of euryhaline crustaceans. This study sought to evaluate the potential for blue crab culture in ILSW for commercial aquaculture and as a potential nursery for restoration efforts. A 21-d bioassay was conducted using four different pond waters of differing ionic composition and salinity (2.0–5.7‰). No significant differences in survival, weight gain (%), and final weight were observed among different pond waters. An on-farm demonstration was conducted in a 1.5-acre low-salinity pond (5.0‰) at a shrimp farm in west Alabama. Crabs grew from 2.0 to 202.0 g in less than 120 d when offered a varied diet of commercial shrimp feed, catfish offal, and fresh whole catfish. Results from these trials suggest that there is excellent biological potential for culture of blue crabs in ILSW of west Alabama.
Evaluation of Hydrogen Peroxide and Temperature to Control Mortality Caused by Saprolegniasis and to Increase Hatching Success of Largemouth Bass Eggs
Authors: Matthews Michael D , Sakmar Joshua C , Trippel Nick
Published: September 2012

We evaluated the use of hydrogen peroxide (H2O2), temperature, or both, to control mortality presumptively caused by fungus Saprolegnia in Florida largemouth bass Micropterus salmoides floridanus eggs in a flow-through hatchery system. Four treatments—ambient water (AW; control), ambient water and H2O2 (AWHP), heated water (HW), and both heated water and H2O2 (HWHP)—were tested on each of 30 replicate spawns. Four 8 cm × 5 cm sections of spawning mat, one for each treatment, were cut from each of the 30 selected spawns. Egg counts on each cut mat section were recorded. Water temperature in all AW and HW trial tanks ranged from 17.9°C to 19.2°C and from 22.1°C to 23.6°C, respectively, during treatment. The water temperature difference between treatments averaged 4.4°C. Hydrogen peroxide trial tanks received two, 100 mg/L H2O2 treatments 8 h apart, until hatch. The 7.5 L/min incoming water flow was not reduced during treatment. The addition of HW, H2O2, or both, significantly increased mean percent hatch (79, 79, and 91%, respectively) over that of the untreated controls (49%). Significant differences were found in mean percent hatch levels between AW and the other three treatment groups (P < 0.05). The combination of higher incubation temperature and H2O2 administration also resulted in significantly greater hatch than did either higher incubation temperature or increased H2O2 administration alone; percent hatch did not differ significantly between eggs that either were only incubated at the higher temperature or received only H2O2 administration. Increasing incubation water temperature to 22–23°C instead of using only water at ambient temperature (18–19°C) or adding 100 mg/L H2O2 twice daily in a flow-through system significantly increased hatching percentage of Florida largemouth bass eggs.
A Comparative Analysis of the Economic Risk of Hybrid Striped Bass Fingerling Production in Ponds and Indoor Tanks
Authors: Engle Carole , Sapkota Pratikshya
Published: September 2012

A risk analysis was conducted to compare the economic risk of producing hybrid striped bass (♀ white bass Morone chrysops × ♂ striped bass M. saxatilis) fingerlings in ponds and indoor tanks. Cost budgets developed previously for three pond sizes (0.4, 1.2, and 2.4 ha) and three tank sizes (945, 2,457, and 5,670 L) for each of six scales of production (50,000, 100,000, 250,000, 500,000, 1,000,000, and 2,000,000 fingerlings/year) were used as the initial starting point for the development of a spreadsheet-based risk analysis. Probability distributions and cumulative frequency distributions of break-even prices above total costs were calculated for each scenario. Pond production was less risky than tank production, and larger pond sizes had lower risk. Survival rates contributed the most to the economic risk of hybrid striped bass fingerling production. Research is needed to improve survival rates for hybrid striped bass fingerling production in ponds.
Spelling–stress regularity effects are intact in developmental dyslexia
Authors: Mundy Ian R. , Carroll Julia M.
Published: September 2012

The current experiment investigated conflicting predictions regarding the effects of spelling–stress regularity on the lexical decision performance of skilled adult readers and adults with developmental dyslexia. In both reading groups, lexical decision responses were significantly faster and significantly more accurate when the orthographic structure of a word ending was a reliable as opposed to an unreliable predictor of lexical stress assignment. Furthermore, the magnitude of this spelling–stress regularity effect was found to be equivalent across reading groups. These findings are consistent with intact phoneme-level regularity effects also observed in dyslexia. The paper discusses how findings of intact spelling–sound regularity effects at both prosodic and phonemic levels, as well as other similar results, can be reconciled with the obvious difficulties that people with dyslexia experience in other domains of phonological processing.
Disruption of SIRPα signaling in macrophages eliminates human acute myeloid leukemia stem cells in xenografts
Authors: Theocharides Alexandre P.A. , Jin Liqing , Cheng Po-Yan , Prasolava Tatiana K. , Malko Andrei V. , Ho Jenny M. , Poeppl Armando G. , van Rooijen Nico , Minden Mark D. , Danska Jayne S. , Dick John E. , Wang Jean C.Y.
Published: September 2012

Although tumor surveillance by T and B lymphocytes is well studied, the role of innate immune cells, in particular macrophages, is less clear. Moreover, the existence of subclonal genetic and functional diversity in some human cancers such as leukemia underscores the importance of defining tumor surveillance mechanisms that effectively target the disease-sustaining cancer stem cells in addition to bulk cells. In this study, we report that leukemia stem cell function in xenotransplant models of acute myeloid leukemia (AML) depends on SIRPα-mediated inhibition of macrophages through engagement with its ligand CD47. We generated mice expressing SIRPα variants with differential ability to bind human CD47 and demonstrated that macrophage-mediated phagocytosis and clearance of AML stem cells depend on absent SIRPα signaling. We obtained independent confirmation of the genetic restriction observed in our mouse models by using SIRPα-Fc fusion protein to disrupt SIRPα–CD47 engagement. Treatment with SIRPα-Fc enhanced phagocytosis of AML cells by both mouse and human macrophages and impaired leukemic engraftment in mice. Importantly, SIRPα-Fc treatment did not significantly enhance phagocytosis of normal hematopoietic targets. These findings support the development of therapeutics that antagonize SIRPα signaling to enhance macrophage-mediated elimination of AML.
ANALYSIS OF SEEING-INDUCED POLARIZATION CROSS-TALK AND MODULATION SCHEME PERFORMANCE
Authors: Casini R. , de Wijn A. G. , Judge P. G.
Published: September 2012

We analyze the generation of polarization cross-talk in Stokes polarimeters by atmospheric seeing, and its effects on the noise statistics of spectropolarimetric measurements for both single-beam and dual-beam instruments. We investigate the time evolution of seeing-induced correlations between different states of one modulation cycle and compare the response to these correlations of two popular polarization modulation schemes in a dual-beam system. Extension of the formalism to encompass an arbitrary number of modulation cycles enables us to compare our results with earlier work. Even though we discuss examples pertinent to solar physics, the general treatment of the subject and its fundamental results might be useful to a wider community.
Causal stability ranking
Authors: Stekhoven Daniel J. , Moraes Izabel , Sveinbjörnsson Gardar , Hennig Lars , Maathuis Marloes H. , Bühlmann Peter
Published: September 2012

Genotypic causes of a phenotypic trait are typically determined via randomized controlled intervention experiments. Such experiments are often prohibitive with respect to durations and costs, and informative prioritization of experiments is desirable. We therefore consider predicting stable rankings of genes (covariates), according to their total causal effects on a phenotype (response), from observational data. Since causal effects are generally non-identifiable from observational data only, we use a method that can infer lower bounds for the total causal effect under some assumptions. We validated our method, which we call Causal Stability Ranking (CStaR), in two situations. First, we performed knock-out experiments with Arabidopsis thaliana according to a predicted ranking based on observational gene expression data, using flowering time as phenotype of interest. Besides several known regulators of flowering time, we found almost half of the tested top ranking mutants to have a significantly changed flowering time. Second, we compared CStaR to established regression-based methods on a gene expression dataset of Saccharomyces cerevisiae. We found that CStaR outperforms these established methods. Our method allows for efficient design and prioritization of future intervention experiments, and due to its generality it can be used for a broad spectrum of applications.

Availability: The full table of ranked genes, all raw data and an example R script for CStaR are available from the Bioinformatics website.

Contact:  stekhoven@stat.math.ethz.ch

Supplementary Information:  Supplementary data are available at Bioinformatics online.
Labeling and Confocal Imaging of Neurons in Thick Invertebrate Tissue Samples
Authors: Gonzalez-Bellido Paloma T. , Wardill Trevor J.
Published: September 2012

Neuroscience researchers have long sought methods to describe the neural connectivity of the circuits responsible for specific behaviors. One major obstacle is scale: Neural spines can be <1 µm in diameter, but axons can range from millimeters to centimeters (or larger) in length, making tissue imaging and neuron reconstruction a challenging task. New tissue-clearing agents and long-working-distance objectives offer improved imaging conditions, and here we present a complete protocol for invertebrate tissue that uses these advances. In this protocol, tissue-processing steps previously published in separate articles are combined with recent advances in confocal imaging to visualize invertebrate tissue samples that are >500 µm thick and contain dye-filled neurons. The steps describe dye filling, fixing, antibody labeling, clearing, whole tissue mounting, and confocal imaging with matched refractive indexes. Thus, manual sectioning or “flipping” the tissue to image the whole volume is not required. With matched refractive indexes, loss of resolution and signal is avoided. Tissue volumes are imaged in one stack and nonlinear deformations caused by tissue flipping are prevented. We apply the protocol to whole dragonfly thoracic ganglia (2 × 1 × 0.6 mm) and cephalopod skin samples (20 × 2 × 0.6 mm) with minimal tissue deformation. The resulting images will be used to develop a three-dimensional connectivity atlas of dragonfly ganglia and cephalopod skin innervation. This protocol can be applied to other invertebrate species, and has the advantage that it avoids problems with antigen specificity.
Imaging Axon Pathfinding in Xenopus In Vivo
Authors: Leung Louis , Holt Christine E.
Published: September 2012

Axon pathfinding in the developing animal involves a highly dynamic process in which the axonal growth cone makes continuous decisions as it navigates toward its target. Changes occurring in the growth cone with respect to retracting from or extending into complex new territories can occur in minutes. Thus, the advent of strategies to visualize axon path-finding in vivo in a live intact animal is crucial for a better understanding of how the growth cone makes such rapid decisions in response to multiple cues. Combining these strategies with loss-of-function and/or gain-of-function techniques allows one to gain some insight as to which molecules are crucial to particular growth cone behaviors at specific choice points during navigation. The main advantage of using Xenopus lies in the accessibility of major axon tracts for live microscopy, as their embryonic development occurs ex utero. Furthermore, the robust embryos remain healthy during immobilization and allow for good imaging for long periods. This protocol describes the methods for stabilizing and preparing live Xenopus embryos for imaging labeled axonal tracts at high spatial and temporal resolution for up to 72 h. This approach can been used to investigate how the knockdown of certain gene functions can affect the speed of navigation through the well-studied Xenopus retinotectal pathway. It can be adapted to visualize other axon tracts of interest.
Imaging Axon Pathfinding in Zebrafish In Vivo: Figure 1.
Authors: Leung Louis , Holt Christine E.
Published: September 2012

Axon pathfinding in the developing animal involves a highly dynamic process in which the axonal growth cone makes continuous decisions as it navigates toward its target. Changes occurring in the growth cone with respect to retracting from or extending into complex new territories can occur in minutes. Thus, the advent of strategies to visualize axon path­finding in vivo in a live intact animal is crucial for a better understanding of how the growth cone makes such rapid decisions in response to multiple cues. Combining these strategies with loss-of-function and/or gain-of-function techniques, one can gain some insight as to which molecules are crucial to particular growth cone behaviors at specific choice points during navigation. The major advantage of using zebrafish lies in the accessibility of major axon tracts for live microscopy, as their embryonic development occurs ex utero. Furthermore, the robust embryos remain healthy during immobilization and allow for good imaging for long periods. This protocol describes the method for stabilizing and preparing live zebrafish embryos for imaging labeled axonal tracts at high spatial and temporal resolution for up to 72 h. It has been used for retinotectal axon pathfinding, but can be adapted to visualize other axon tracts of interest.
Bacterial RNA Isolation
Authors: Ares Manuel
Published: September 2012

In this bacterial RNA isolation protocol, an “RNA-protective” treatment is followed by lysozyme digestion of the peptidoglycan component of the cell wall. EDTA promotes the loss of the outer membrane of Gram-negative bacteria and allows the lysozyme better access to the peptidoglycan. Cells begin to lyse during digestion in hypotonic lysozyme buffer and lysis is completed by sodium dodecyl sulfate (SDS) and hot phenol:chloroform:isoamyl alcohol (PCA) extraction. SDS and hot phenol disrupt membranes, denature protein (including RNase), and strip proteins from RNA. The separation of the organic phase from the aqueous phase is achieved using Phase Lock Gel, an inert material with a density intermediate between the organic and aqueous samples. The sample is split into three phases: from bottom to top, these are phenol and chloroform (organic phase), the inert gel with the interface material, and the aqueous phase with the RNA. The gel acts as a physical barrier between the sample and the organic phase plus interface. Following organic extraction, the RNA is concentrated by ethanol precipitation.
Stimulant and non‐stimulant attention deficit/hyperactivity disorder drug use: total population study of trends and discontinuation patterns 2006–2009
Authors: Zetterqvist J. , Asherson P. , Halldner L. , Långström N. , Larsson H.
Published: September 2012

Zetterqvist J, Asherson P, Halldner L, Långström N, Larsson H. Stimulant and non‐stimulant attention deficit/hyperactivity disorder drug use: total population study of trends and discontinuation patterns 2006–2009.

Objective:  To explore the prevalence and discontinuation of dispensed medications for attention deficit/hyperactivity disorder (ADHD) drugs from 2006 to 2009.

Method:  A total population cohort of all individuals aged 6–45 years, alive and registered as residents in Sweden during any calendar year from 2006 to 2009 (N = 5 149 791) included 41 700 patients dispensed with an ADHD drug (methylphenidate, atomoxetine, amphetamine, or dexamphetamine). The dispensing prevalence was calculated for each year, stratified on sex and age. A longitudinal analysis was also performed to compare the rates of treatment discontinuation across the strata.

Results:  The dispensing prevalence increased from 2.93 per 1000 in 2006 to 6.98 in 2009 (PR = 2.38, 95% CI = 2.34–2.43). The prevalence ratio (PR) was 3.40 for adults, 22–45 years old; 2.41 for adolescents, 15–21 years old; and 1.90 for children aged 6–14. The increase was also greater in women than in men (PR = 2.92 vs. 2.19). Patients aged 15–21 were the most likely to discontinue treatment; after 3 years and 11 months, 27% of those patients were still under treatment.

Conclusion:  From 2006 to 2009, the number of prescriptions dispensed for ADHD drugs increased substantially. The rate of treatment discontinuation in the age interval 15–21 is higher than expected considering the persistence rates of the disorder.
Neurodevelopmental outcome at 6 years of age after intrauterine laser therapy for twin‐twin transfusion syndrome
Authors: Graeve Pauline , Banek Corinna , Stegmann‐Woessner Gaby , Maschke Cornelia , Hecher Kurt , Bartmann Peter
Published: September 2012

This study was undertaken to evaluate neurodevelopmental outcome of children at 6 years of age after intrauterine laser therapy for Twin‐twin transfusion syndrome (TTTS).

This is part of a longitudinal study in children after intrauterine laser therapy for TTTS; 190 of 254 (74.8%) children, previously investigated at a median age of 2 years 10 months, were re‐evaluated at 6 years 5 months (range 4 years 11 months –10 years 4 months). Sixty‐four patients were not examined due to loss of contact. The median gestational age at birth was 34 + 3 weeks. The study included a physical/neurological examination, a standardized neurodevelopmental test (Kaufman‐ABC) and/or results from the national screening programme for children as well as questionnaires. Patients were grouped in three outcome categories: group I: normal examination and test result; group II: minor neurological deficiencies and normal test results; group III: major neurological deficiencies and/or test results below minus two standard deviations.

The following results were obtained at 6 years 5 months (for comparison, results of the same patients at 2 years 10 months in brackets). Group I: 79.5% (84.2%); group II: 11.6% (8.9%); group III: 8.9% (6.8%). Twenty‐one (11%) patients had a worse and 8 (4.2%) an improved classification at 6 years 5 months as compared to 2 years 10 months. Overall, the results with 6 years did not significantly differ from the results with 2 years.

Neurodevelopmental outcome at 6 years 5 months was not statistically, significantly different from outcome at 2 years 10 months.