bluuebunny/crossref_metadata_2025 huggingface dataset:
Anisotropy-enhanced giant reversible rotating magnetocaloric effect in HoMn2O5 single crystals
Authors: Balli M. , Jandl S. , Fournier P. , Gospodinov M. M.
Published: June 2014

Magnetic and magnetocaloric properties of HoMn2O5 single crystals were investigated. HoMn2O5 undergoes a large conventional magnetocaloric effect around 10 K. The magnetocaloric effect was found to present a giant anisotropy. Consequently, a large magnetocaloric effect (−ΔSR,max= 12.43 J/kg K for 7 T) can be obtained simply by rotating the single crystal HoMn2O5 within the cb plane in constant magnetic field instead of moving it in and out of the magnetic field zone. This can open the way for the implementation of compact, simplified, and efficient rotary magnetic refrigerators.
Three-dimensional instabilities in a discretely heated annular flow: Onset of spatio-temporal complexity via defect dynamics
Authors: Lopez Juan M. , Marques Francisco
Published: June 2014

The transition to three-dimensional and unsteady flow in an annulus with a discrete heat source on the inner cylinder is studied numerically. For large applied heat flux through the heater (large Grashof number Gr), there is a strong wall plume originating at the heater that reaches the top and forms a large scale axisymmetric wavy structure along the top. For Gr ≈ 6 × 109, this wavy structure becomes unstable to three-dimensional instabilities with high azimuthal wavenumbers m ∼ 30, influenced by mode competition within an Eckhaus band of wavenumbers. Coexisting with some of these steady three-dimensional states, solution branches with localized defects break parity and result in spatio-temporal dynamics. We have identified two such time dependent states. One is a limit cycle that while breaking spatial parity, retains spatio-temporal parity. The other branch corresponds to quasi-periodic states that have globally broken parity.
Design, fabrication and characterization of a monolithic focusing piezoceramic transducer for an anisotropic material
Authors: Souris Fabien , Grucker Jules , Garroum Nabil , Leclercq Arnaud , Isac Jean-Michel , Dupont-Roc Jacques , Jacquier Philippe
Published: June 2014

Piezoceramic transducers shaped as spherical caps are widely used to focus ultrasound waves in isotropic materials. For anisotropic materials, the sound wave surface is not spherical and the transducer surface should be adjusted to reproduce a portion of this wave surface to focus the emitted sound properly. In this article, we show how to design such a transducer and how to fabricate it in lab on a standard machine from a rod of raw piezo ceramic material. The main features of its electrical impedance response are well reproduced by a numerical model, allowing the identification of most of its vibrational modes. We finally measured the sound field emitted by such a transducer and found its focusing efficiency similar to that of spherical caps in isotropic media.
Twinnability of hcp metals at the nanoscale
Authors: Guo Ya-Fang , Xu Shuang , Tang Xiao-Zhi , Wang Yue-Sheng , Yip Sidney
Published: June 2014

Twinning is generally considered to be the primary deformation mechanism for hexagonal close-packed (hcp) metals due to their limited slip systems. Recent microcompression experiments point to strong size effects indicating that pyramidal slips can dominate in deformation under compression. We present analysis on the twinnability of an ideal hcp single crystal at the nanoscale. A criterion for deformation twinning is derived by considering the elastic lattice-rotation strain, and the result tested against molecular dynamics simulations of magnesium and titanium single crystals. We find ⟨c + a⟩ pyramidal slip dominates the compression deformation at the nanoscale, which is consistent with experimental observations on microcompression. This analysis gives an interpretation of size effects in deformation twinning, at the same time it provides an explanation for the so-called strength differential effect.
Two-step polarization reversal in biased ferroelectrics
Authors: Daniels John E. , Cozzan Clayton , Ukritnukun Supphatuch , Tutuncu Goknur , Andrieux Jerome , Glaum Julia , Dosch Chris , Jo Wook , Jones Jacob L.
Published: June 2014

Polarization reversal in polycrystalline ferroelectrics is shown to occur via two distinct and sequential domain reorientation steps. This reorientation sequence, which cannot be readily discriminated in the overall sample polarization, is made apparent using time-resolved high-energy x-ray diffraction. Upon application of electric fields opposite to the initial poling direction, two unique and significantly different time constants are observed. The first (faster time constant) is shown to be derived by the release of a residual stress due to initial electrical biasing and the second (slower time constant) due to the redevelopment of residual stress during further domain wall motion. A modified domain reorientation model is given that accurately describes the domain volume fraction evolution during the reversal process.
Threshold ionization, structural isomers, and electronic states of M2O2 (M = Sc, Y, and La)
Authors: Wu Lu , Zhang Changhua , Krasnokutski Serge A. , Yang Dong-Sheng
Published: June 2014

M2O2 (M = Sc, Y, and La) were synthesized in a pulsed laser-vaporization molecular beam source and studied by mass-analyzed threshold ionization (MATI) spectroscopy and ab initio calculations. Adiabatic ionization energies (AIEs) and several vibrational frequencies were measured accurately for the first time from the MATI spectra. Six possible structural isomers of M2O2 were considered in the calculations and the three converged structures were used in the spectral analysis. A planar cyclic structure in D2h point group was predicted to be the most stable one by the theory and observed by the experiment. The cyclic structure is formed by joining two MO2 fragments together through two shared oxygen atoms. In forming the ground state clusters, each metal atom loses two (n − 1)d electrons and as a result, has only one ns electron in the metal-based valence orbital. The ground electronic state of Sc2O2 is 1Ag, and those of Y2O2 and La2O2 are 3B1u. Ionization of both 1Ag and 3B1u neutral states yields the 2Ag ion state by removing one of the two ns electrons, and the resultant ion has a similar geometry to the neutral cluster. The AIEs of the clusters are 5.5752 (6), 5.2639 (6), 4.5795 (6) eV for M = Sc, Y, and La, respectively. The vibrational frequencies of the observed modes, including O-M and M-M stretches, are in the range of 200–800 cm−1.
Two-band superlinear electroluminescence in GaSb based nanoheterostructures with AlSb/InAs1−x Sbx/AlSb deep quantum well
Authors: Mikhailova M. P. , Ivanov E. V. , Danilov L. V. , Petukhov A. A. , Kalinina K. V. , Slobozhanyuk S. I. , Zegrya G. G. , Stoyanov N. D. , Yakovlev Yu. P. , Hospodková A. , Pangrác J. , Oswald J. , Zíková M. , Hulicius E.
Published: June 2014

We report on superlinear electroluminescent structures based on AlSb/InAs1−xSbx/AlSb deep quantum wells grown by MOVPE on n-GaSb:Te substrates. Dependence of the electroluminescence (EL) spectra and optical power on the drive current in nanoheterostructures with AlSb/InAs1−xSbx/AlSb quantum well at 77–300 K temperature range was studied. Intensive two-band superlinear EL in the 0.5–0.8 eV photon energy range was observed. Optical power enhancement with the increasing drive current at room temperature is caused by the contribution of the additional electron-hole pairs due to the impact ionization by the electrons heated at the high energy difference between AlSb and the first electron level Ee1 in the InAsSb QW. Study of the EL temperature dependence at 90–300 K range enabled us to define the role of the first and second heavy hole levels in the radiative recombination process. It was shown that with the temperature decrease, the relation between the energies of the valence band offset and the second heavy hole energy level changes due to the temperature transformation of the energy band diagram. That is the reason why the EL spectrum revealed radiative transitions from the first electron level Ee1 to the first hole level Eh1 in the whole temperature range (90–300 K), while the emission band related with the transitions to the second hole level occurred only at T > 200 K. Comparative examination of the nanostructures with high band offsets and different interface types (AlAs-like and InSb-like) reveals more intense EL and optical power enhancement at room temperature in the case of AlAs-like interface that could be explained by the better quality of the heterointerface and more efficient hole localization.
Observation of room temperature optical absorption in InP/GaAs type-II ultrathin quantum wells and quantum dots
Authors: Singh S. D. , Porwal S. , Mondal Puspen , Srivastava A. K. , Mukherjee C. , Dixit V. K. , Sharma T. K. , Oak S. M.
Published: June 2014

Room temperature optical absorption process is observed in ultrathin quantum wells (QWs) and quantum dots (QDs) of InP/GaAs type-II band alignment system using surface photovoltage spectroscopy technique, where no measurable photoluminescence signal is available. Clear signature of absorption edge in the sub band gap region of GaAs barrier layer is observed for the ultrathin QWs and QDs, which red shifts with the amount of deposited InP material. Movement of photogenerated holes towards the sample surface is proposed to be the main mechanism for the generation of surface photovoltage in type-II ultrathin QWs and QDs. QDs of smaller size are found to be free from the dislocations as confirmed by the high resolution transmission electron microscopy images.
Extension of Chern-Simons forms
Authors: Konitopoulos Spyros , Savvidy George
Published: June 2014

We investigate metric independent, gauge invariant, and closed forms in the generalized Yang-Mills (YM) theory. These forms are polynomial on the corresponding fields strength tensors – curvature forms and are analogous to the Pontryagin-Chern densities in the YM gauge theory. The corresponding secondary characteristic classes have been expressed in integral form in analogy with the Chern-Simons form. Because they are not unique, the secondary forms can be dramatically simplified by the addition of properly chosen differentials of one-step-lower-order forms. Their gauge variation can also be found yielding the potential anomalies in the gauge field theory.
Dynamics of Johari-Goldstein β relaxation and its universal relation to α relaxation in bulk metallic glasses by mechanical spectroscopy
Authors: Wu Xuebang , Guo Lijun , Liu C. S.
Published: June 2014

The dynamics of the Johari–Goldstein (JG) β relaxation and the α relaxation in bulk metallic glasses (MGs) has been investigated by using mechanical spectroscopy combined with the Coupling Model. The β relaxations of MGs exhibit different behaviors such as peaks, humps, and excess wings due to the different fluctuations of the chemical interactions among the constituting atoms. A universal correlation between the β relaxation and the α relaxation is generally found by their activation energies and relaxation times as well as the non-exponentiality parameter of the α relaxation, which can be predicted quantitatively from the Coupling Model. Based on the quasi-point defects theory, a correlation factor χ shows a broad peak along with the β relaxation, suggesting that the concentration and the correlation degree of the string-like configurations involved in the β relaxation vary with increasing temperature, which challenges the previous view that the system is in an iso-configuration state below Tg and may shed new light on the nature of the JG β relaxation in metallic glasses.
Ultrasonicated double wall carbon nanotubes for enhanced electric double layer capacitance
Authors: Pandey Srikrishna , Maiti Uday N. , Palanisamy Kowsalya , Nikolaev Pavel , Arepalli Sivaram
Published: June 2014

An intense ultrasonication of the double wall carbon nanotubes (DWCNTs) causes fractures and splitting of the individual tubes. This not only generates open tips and edges in DWCNTs but also incorporates defects in the tube walls. The electric double layer capacitor (EDLC) electrodes of intensively ultrasonicated DWCNTs (U-DWCNTs) form organized layered-porous structures. The EDLC behavior of U-DWCNTs electrodes shows dramatic improvements (specific capacitance 10 times and 222 times larger than the pristine DWCNTs at scan rates 5 mV s−1 and 500 mV s−1, respectively) due to the increased wettability of electrodes and accessibility of the electrolyte ions.
Heating mode transition in a hybrid direct current/dual-frequency capacitively coupled CF4 discharge
Authors: Zhang Quan-Zhi , Wang You-Nian , Bogaerts Annemie
Published: June 2014

Computer simulations based on the particle-in-cell/Monte Carlo collision method are performed to study the plasma characteristics and especially the transition in electron heating mechanisms in a hybrid direct current (dc)/dual-frequency (DF) capacitively coupled CF4 discharge. When applying a superposed dc voltage, the plasma density first increases, then decreases, and finally increases again, which is in good agreement with experiments. This trend can be explained by the transition between the four main heating modes, i.e., DF coupling, dc and DF coupling, dc source dominant heating, and secondary electron dominant heating.
Structure determination of the high-pressure phase of CdSe
Authors: Li Yanchun , Lin Chuanlong , Li Gong , Xu Jian , Li Xiaodong , Liu Jing
Published: June 2014

Structural phase transition sequence of CdSe has been investigated at pressures up to 60 GPa under quasi-hydrostatic conditions using synchrotron X-ray diffraction. A phase transition from the wurtzite type (B4) to the NaCl-type (B1) structure has been observed, followed by another phase transition to an orthorhombic structure at 27 GPa, in agreement with previous reports. We show that this high-pressure orthorhombic phase has a Pnma symmetry rather than being a Cmcm-symmetric structure as previously suggested. From our observations, the appearance of the new reflections and reflection splitting with increasing pressure is due to the change of atomic relative positions in crystal lattice and the difference in the compression ratio of lattice parameters for the Pnma structure, and we find no evidence for the third phase transition reported previously. The pressure-induced phase transition of CdSe has been further confirmed by the density-functional theory calculations.
Piezoreflectance study of near band edge excitonic-transitions of mixed-layered crystal Mo(SxSe1-x)2 solid solutions
Authors: Wu Y. J. , Wu P. H. , Jadczak J. , Huang Y. S. , Ho C. H. , Hsu H. P. , Tiong K. K.
Published: June 2014

The temperature dependence of the spectral features in the vicinity of the direct band edge of mixed-crystals Mo(SxSe1-x)2 solid solutions is measured in the temperature range of 25–295 K by using piezoreflectance (PzR). The near band-edge excitonic transition energies of Mo(SxSe1-x)2 solid solutions were determined accurately from a detailed line-shape fit of the PzR spectra. The near band-edge excitonic transition energies were found to vary smoothly with the increase of S content x, indicating that the natures of the direct band edges of Mo(SxSe1-x)2 solid solutions are similar. The temperature dependences of near band edge transition energies were analyzed using Bose-Einstein expressions in the temperature range from 25 to 295 K. The parameters that described the temperature variation of the energies and broadening function of the excitonic transitions were evaluated and discussed.
Stable long range proton acceleration driven by intense laser pulse with underdense plasmas
Authors: Gu Y. J. , Zhu Z. , Li X. F. , Yu Q. , Huang S. , Zhang F. , Kong Q. , Kawata S.
Published: June 2014

Proton acceleration is investigated by 2.5-dimensional particle-in-cell simulations in an interaction of an ultra intense laser with a near-critical-density plasma. It was found that multi acceleration mechanisms contribute together to a 1.67 GeV collimated proton beam generation. The W-BOA (breakout afterburner based on electrons accelerated by a wakefield) acceleration mechanism plays an important role for the proton energy enhancement in the area far from the target. The stable and continuous acceleration maintains for a long distance and period at least several pico-seconds. Furthermore, the energy scalings are also discussed about the target density and the laser intensity.
Toroidal momentum transport in a tokamak due to profile shearing
Authors: Buchholz R. , Camenen Y. , Casson F. J. , Grosshauser S. R. , Hornsby W. A. , Migliano P. , Peeters A. G.
Published: June 2014

The effect of profile shearing on toroidal momentum transport is studied in linear and non-linear gyro-kinetic simulations. Retaining the radial dependence of both plasma and geometry parameters leads to a momentum flux that has contributions both linear in the logarithmic gradients of density and temperature, as well as contributions linear in the derivatives of the logarithmic gradients. The effect of the turbulence intensity gradient on momentum transport is found to be small for the studied parameters. Linear simulations at fixed normalized toroidal wave number predict a weak dependence of the momentum flux on the normalized Larmor radius ρ*=ρ/R. Non-linear simulations, however, at sufficiently small ρ* show a linear scaling of the momentum flux with ρ*. The obtained stationary rotation gradients are in the range of, although perhaps smaller than, current experiments. For a reactor plasma, however, a rather small rotation gradient should result from profile shearing.
Ultrafast dynamics of a near-solid-density layer in an intense femtosecond laser-excited plasma
Authors: Adak Amitava , Blackman David R. , Chatterjee Gourab , Kumar Singh Prashant , Lad Amit D. , Brijesh P. , Robinson A. P. L. , Pasley John , Kumar G. Ravindra
Published: June 2014

We report on the picosecond dynamics of a near-solid-density plasma generated by an intense, infrared (λ = 800 nm) femtosecond laser using time-resolved pump-probe Doppler spectrometry. An initial red-shift is observed in the reflected third harmonic (λ = 266 nm) probe pulse, which gets blue-shifted at longer probe-delays. A combination of particle-in-cell and radiation-hydrodynamics modelling is performed to model the pump laser interaction with the solid target. The results are post-processed to predict the Doppler shift. An excellent agreement is found between the results of such modelling and the experiment. The modelling suggests that the initial inward motion of the critical surface observed in the experiment is due to the passage of a shock-wave-like disturbance, launched by the pump interaction, propagating into the target. Furthermore, in order to achieve the best possible fit to the experimental data, it was necessary to incorporate the effects of bulk ion-acceleration resulting from the electrostatic field set up by the expulsion of electrons from the laser envelope. We also present results of time-resolved pump-probe reflectometry, which are corroborated with the spectrometry results using a 1-D reflectivity model.
Intermittent laser-plasma interactions and hot electron generation in shock ignition
Authors: Yan R. , Li J. , Ren C.
Published: June 2014

We study laser-plasma interactions and hot electron generation in the ignition phase of shock ignition through 1D and 2D particle-in-cell simulations in the regime of long density scale length and moderately high laser intensity. These long-term simulations show an intermittent bursting pattern of laser-plasma instabilities, resulting from a coupling of the modes near the quarter-critical-surface and those in the lower density region via plasma waves and laser pump depletion. The majority of the hot electrons are found to be from stimulated Raman scattering and of moderate energies. However, high energy electrons of preheating threat can still be generated from the two-plasmon-decay instability.
Large magnetic entropy change and adiabatic temperature rise of a Gd55Al20Co20Ni5 bulk metallic glass
Authors: Xia L. , Tang M. B. , Chan K. C. , Dong Y. D.
Published: June 2014

Gd55Al20Co20Ni5 bulk metallic glass (BMG) was synthesized by minor Ni substitution for Co in the Gd55Al20Co25 BMG in which excellent glass forming ability (GFA) and magneto-caloric effect were reported previously. The Gd55Al20Ni20Co5 amorphous rod has a similar GFA to the Gd55Al20Co25 BMG but exhibits better magnetic properties. The peak value of magnetic entropy change (−ΔSmpeak) of the Gd55Al20Co20Ni5 BMG is 9.8 Jkg−1 K−1. The field dependence of −ΔSmpeak follows a −ΔSmpeak∝H0.85 relationship. The adiabatic temperature rise of the rod is 4.74 K under 5 T and is larger than of other BMGs previously reported. The improved magnetic properties were supposed to be induced by the enhanced interaction between 4f electron in the rare-earth and 3d electron in the transition metal elements by means of a minor Ni substitution for Co.
Characteristic emission enhancement in the atmosphere with Rn trace using metal assisted LIBS
Authors: Hashemi M. M. , Parvin P. , Moosakhani A. , Mortazavi S. Z. , Majdabadi A. , Reyhani A. , Abachi S.
Published: June 2014

Several characteristic emission lines from the metal targets (Cu, Zn and Pb) were investigated in trace presence of radon gas in the atmospheric air, using Q-SW Nd:YAG laser induced plasma inside a control chamber. The emission lines of metal species are noticeably enhanced in (Rn+air), relative to those in the synthetic air alone. Similar spectra were also taken in various sub-atmospheric environments in order to determine the optimum pressure for enhancement. Solid-state nuclear track detectors were also employed to count the tracks due to alpha particles for the activity assessment.
Magnetocaloric effect in multiferroic Y-type hexaferrite Ba0.5Sr1.5Zn2(Fe0.92Al0.08)12O22
Authors: Xu Wenfei , Yang Jing , Shen Yude , Bai Wei , Zhang Yuanyuan , Liu Jia , Tang Kai , Wang Zhi , Duan Chun-gang , Tang Xiaodong , Chu Junhao
Published: June 2014

Magnetocaloric effect is investigated in multiferroic Ba0.5Sr1.5Zn2(Fe0.92Al0.08)12O22 ceramic with Y-type hexagonal system. Three magnetic transitions, from alternating longitudinal conical to mixed conical at ∼240 K, to ferrimagnetic at ∼297 K, further to paramagnetic at ∼702 K, are unambiguously determined. Furthermore, obvious MCE is shown, and the maximum values of the magnetic entropy change and relative cooling power are evaluated to be 1.53 JKg−1K−1 and 280 JKg−1 for a field change of 7 T, respectively. In addition, inverse MCE is also observed, which might be associated with the first-order magnetic phase transition between two incommensurate longitudinal conical phases.
Monolithic integration of a quantum emitter with a compact on-chip beam-splitter
Authors: Prtljaga N. , Coles R. J. , O'Hara J. , Royall B. , Clarke E. , Fox A. M. , Skolnick M. S.
Published: June 2014

A fundamental component of an integrated quantum optical circuit is an on-chip beam-splitter operating at the single-photon level. Here, we demonstrate the monolithic integration of an on-demand quantum emitter in the form of a single self-assembled InGaAs quantum dot (QD) with a compact (>10 μm), air clad, free standing directional coupler acting as a beam-splitter for anti-bunched light. The device was tested by using single photons emitted by a QD embedded in one of the input arms of the device. We verified the single-photon nature of the QD signal by performing Hanbury Brown-Twiss measurements and demonstrated single-photon beam splitting by cross-correlating the signal from the separate output ports of the directional coupler.
Synergistic Antibacterial Activity of Nanohybrid Materials ZnO–Ag and ZnO–Au: Synthesis, Characterization, and Comparative Analysis of Undoped and Doped ZnO Nanoparticles
Authors: Jiménez Adriana Berenice Pérez , Aguilar Carlos Alberto Huerta , Ramos Jorge Manuel Vázquez , Thangarasu Pandiyan
Published: June 2014

ZnO nanoparticles (NPs) were prepared using the hydrothermal method, and then doped with Ag or Au NPs, yielding ZnO NPs, ZnO–Ag NPs, and ZnO–Au NPs, which were characterized by transmission electron microscopy, X-ray diffraction, and energy-dispersive X-ray spectroscopy. The synthesized nanomaterials were analyzed for their antibacterial properties against bacterial strains (Staphylococcus aureus, Bacillus cereus, Escherichia coli, and Salmonella typhi) by qualitative and quantitative assays. Minimal inhibitory concentration (MIC) results show that growth control is more effective for Gram-positive bacteria than for Gram-negative bacteria. Although ZnO NPs and Ag NPs are antibacterial agents, the lowest bacterial growth was observed for ZnO–Ag NPs, showing that the doped Ag NPs greatly facilitate the interaction between the microbial cells and the NP surface. Though the same antibacterial effect was expected for ZnO–Au NPs, the inhibition activity was very close to that of ZnO NPs. The order of bacterial cell growth inhibition was ZnO–Ag NPs >> ZnO–Au NPs ~ ZnO NPs >> ZnO powder. We also analyzed the morphology of bacterial cells treated with NPs by scanning electron microscopy.
Microwave Flash Pyrolysis: C9H8 Interconversions and Dimerisations
Authors: Ajaz Aida , Voukides Alicia C. , Cahill Katharine J. , Thamatam Rajesh , Skraba-Joiner Sarah L. , Johnson Richard P.
Published: June 2014

The pyrolysis of 2-ethynyltoluene, indene, fluorene, and related compounds has been studied by sealed tube microwave flash pyrolysis (MFP), in concert with modelling of putative mechanistic pathways by density functional theory (DFT) computations. In the MFP technique, samples are admixed with graphite and subjected to intense microwave power (150–300 W) in a quartz reaction tube under a nitrogen atmosphere. The MFP reaction of 2-ethynyltoluene gave mostly indene, the product of a Roger Brown rearrangement (1,2-H shift to a vinylidene) followed by insertion. An additional product was chrysene, the likely result of hydrogen atom loss from indene followed by dimerisation. The intermediacy of dimeric bi-indene structures was supported by pyrolysis of bi-indene and by computational models. Benzo[a]anthracene and benzo[c]phenanthrene are minor products in these reactions. These are shown to arise from pyrolysis of chrysene under the same MFP conditions. MFP reaction of fluorene gave primarily bi-fluorene, bifluorenylidene, and dibenzochrysene, the latter derived from a known Stone–Wales rearrangement.
Female sexual dysfunction across the three pregnancy trimesters: an Egyptian study
Authors: Hanafy Samy , Srour Neveen E. , Mostafa Taymour
Published: June 2014

Background
Pregnancy is a special period in the life of women characterised by physical, hormonal and psychological changes that, in conjugation with social and cultural influences, could affect women’s sexuality as well as couples’ sexual relationships. This cross-sectional study aimed to evaluate female sexual dysfunction (FSD) among the three pregnancy trimesters. Methods: A total of 300 healthy heterosexual pregnant Egyptian women with stable marital relationships were included. The Female Sexual Function Index (FSFI) questionnaire was used as a standard method for measuring female sexual function in each pregnancy trimester. Results: There was no significant relationship between FSD and women’s education, work, gravidity and parity. The incidence of FSD demonstrated significant alterations throughout pregnancy, being 68% in the first trimester, decreasing in the second trimester to 51% and increasing to 72% in the third trimester. Sexual desire decreased in the first trimester, was variable in the second trimester and decreased at the end of the third trimester (3.5 ± 1.2, 3.7 ± 1.2 and 3.4 ± 1.1 respectively). Sexual satisfaction declined significantly in the first trimester compared with the second and the third trimesters (4.2 ± 1.1, 4.8 ± 0.8 and 4.6 ± 1.0 respectively). Scores for the arousal, lubrication and orgasm domains were significantly decreased in the third trimester, where pain was increased in the second trimester compared with the first and third trimesters. Conclusion: Female sexual function is affected during pregnancy, with a significant change in all Female Sexual Function Index domains, especially in the first and third trimesters.
Human memory T cells from the bone marrow are resting and maintain long-lasting systemic memory
Authors: Okhrimenko Anna , Grün Joachim R. , Westendorf Kerstin , Fang Zhuo , Reinke Simon , von Roth Philipp , Wassilew Georgi , Kühl Anja A. , Kudernatsch Robert , Demski Sonya , Scheibenbogen Carmen , Tokoyoda Koji , McGrath Mairi A. , Raftery Martin J. , Schönrich Günther , Serra Alessandro , Chang Hyun-Dong , Radbruch Andreas , Dong Jun
Published: June 2014

Significance

Memory T cells are essential components of immunological memory. In the apparent absence of antigen, numbers of recirculating antigen-specific memory T cells dwindle, provoking the question of whether there is immunological memory without memory T cells. Here we show that human memory T cells can reside in the bone marrow as resting cells in terms of proliferation, transcription, and mobility. The repertoire of bone marrow memory T cells is enriched for systemic pathogens representing persistent, recent, and childhood challenges. In terms of absolute numbers, memory T cells specific for systemic antigens are maintained predominantly in the bone marrow, in particular those representing historic encounters.
Militarising – and marginalising? – African Studies USA
Authors: Martin William G. , McQuade Brendan Innis
Published: June 2014

The militarisation of US–African relations has attracted considerable attention in recent years. Left largely unexplored, however, is the question of how this process has involved US-based scholars. This essay examines this process with particular attention to the rapid expansion of military and intelligence research on and in Africa, and, in particular, military and intelligence funding of US Africanists' research including at the major African Studies centres. While the classification of much federal research limits conclusions, it is apparent that military and intelligence priorities are coming to significantly shape the present and future of much research and training.
You Can't Always Get What you Want: The Influence of Unexpected Task Constraint on Voluntary Task Switching
Authors: Weaver Starla M. , Foxe John J. , Shpaner Marina , Wylie Glenn R.
Published: June 2014

The current study assessed the effect that unexpected task constraint, following self-generated task choice, has on task switching performance. Participants performed a modified double-registration voluntary task switching procedure in which participants specified the task they wanted to perform, were presented with a cue that, on the majority of trials, confirmed the choice, and then performed the cued task. On a small portion of trials, participants were cued to perform a task that did not match their choice. Trials on which cues unexpectedly failed to match the chosen task were associated with costs. These costs were particularly large when participants chose to switch tasks but had to unexpectedly repeat the previous task. The results suggest that when participants choose to switch tasks, they prepare for that switch in anticipation of the stimulus, and the preparation is durable such that it cannot be readily undone.
Translational addition theorems for spherical Laplacian functions and their application to boundary-value problems
Authors: Ciric Ioan , Kotuwage Kumara
Published: June 2014

General translational addition theorems are presented for spherical scalar Laplacian functions, and their application to boundary value problems is illustrated. By these theorems, the eigenfunction solutions in a system of spherical coordinates are expressed in terms of the spherical coordinates in another system, translated with respect to the first one. This allows for a rigorous analytic solution to be obtained for Laplacian and Poissonian fields in the presence of arbitrary configurations of spheres by imposing the exact boundary conditions. Complete formulations and solutions are presented for systems of electrically charged spheres and for arrays of perfect conductor spheres in external electric and magnetic fields. Illustrative computation examples are given for three-sphere systems. Numerical results of specified accuracy are generated, which are useful for validating various approximate numerical methods.
On the Kotani-Last and Schrödinger conjectures
Authors: Avila Artur
Published: June 2014

In the theory of ergodic one-dimensional Schrödinger operators, the ac spectrum has been traditionally expected to be very rigid. Two key conjectures in this direction state, on the one hand, that the ac spectrum demands almost periodicity of the potential, and, on the other hand, that the eigenfunctions are almost surely bounded in the essential support of the ac spectrum. We show how the repeated slow deformation of periodic potentials can be used to break rigidity, and disprove both conjectures.
A structure theorem for 𝒮𝒰_{𝒞}(2) and the moduli of pointed rational curves
Authors: Alzati Alberto , Bolognesi Michele
Published: June 2014

Let

S
U

C

(
2
)

\mathcal {SU}_C(2)

be the moduli space of rank 2 semistable vector bundles with trivial determinant on a smooth complex algebraic curve

C
C

of genus

g
>
1

g>1

. We assume

C
C

nonhyperellptic if

g
>
2

g>2

. In this paper we construct large families of pointed rational normal curves over certain linear sections of

S
U

C

(
2
)

\mathcal {SU}_C(2)

. This allows us to give an interpretation of these subvarieties of

S
U

C

(
2
)

\mathcal {SU}_C(2)

in terms of the moduli space of curves

M

0
,
2
g

\mathcal {M}_{0,2g}

. In fact, there exists a natural linear map

S
U

C

(
2
)
→

P

g

\mathcal {SU}_C(2) \to \mathbb {P}^g

with modular meaning, whose fibers are birational to

M

0
,
2
g

\mathcal {M}_{0,2g}

, the moduli space of

2
g

2g

-pointed genus zero curves. If

g
>
4

g>4

, these modular fibers are even isomorphic to the GIT compactification

M

0
,
2
g

G
I
T

\mathcal {M}_{0,2g}^{GIT}

. The families of pointed rational normal curves are recovered as the fibers of the maps that classify extensions of line bundles associated to some effective divisors.
Model study of nutrient and phytoplankton dynamics in the Gulf of Maine: patterns and drivers for seasonal and interannual variability
Authors: Tian Rucheng , Chen Changsheng , Qi Jianhua , Ji Rubao , Beardsley Robert C. , Davis Cabell
Published: June 2014

Coupled physical–biological modelling experiments were made for the period of 1995–2009 to analyse the spatial and interannual variability of nutrients and phytoplankton production in the Gulf of Maine (GOM). The physical model was the Finite-Volume Community Ocean Model (FVCOM) and the biological model was a Nitrogen, Phytoplankton, Zooplankton, and Detritus (NPZD) model. The simulation was carried out with realistic meteorological surface forcing, five major tidal constituents, river discharge, and observation-based open boundary conditions. The results were robust with comparison to SeaWiFS chlorophyll data and historical data of nitrogen. An Empirical Orthogonal Function analysis clearly identified two dominant modes in nutrient and phytoplankton dynamics: (1) sustained nutrient supply and phytoplankton production from spring through autumn, and (2) a dominating phytoplankton bloom in spring, relatively low production in summer, and a noticeable bloom in autumn. Mode 1 was a dominant feature in strong tidal energy dissipation regions such as the southwestern shelf of Nova Scotia, Georges Bank, Nantucket Shoals, the Bay of Fundy, and the coastal regions of GOM, where tidal pumping and mixing were the major drivers for the sustained nutrient supply, and primary production showed certain resilience with less interannual variability. Mode 2 was a characteristic in the deep Gulf, the offshore region of the Scotian Shelf, and in the open sea area, where the timing and amplitude of the spring phytoplankton bloom is essentially controlled by the salinity regime, and its interannual variability was significantly influenced by freshening events controlled by local and remote forcing.
Composition temperature-dependent g modes in superfluid neutron stars
Authors: Kantor E. M. , Gusakov M. E.
Published: June 2014

We demonstrate a possibility of existence of peculiar temperature-dependent composition g modes in superfluid neutron stars. We calculate the Brunt–V$\ddot{\rm a}$is$\ddot{\rm a}$l$\ddot{\rm a}$ frequency for these modes, as well as their eigenfrequencies. The latter turn out to be rather large, up to ∼500 Hz for a chosen model of a neutron star. This result indicates, in particular, that use of the barotropic equation of state may be not a good approximation for calculation of inertial modes even in most rapidly rotating superfluid neutron stars.
A no-go theorem for direct collapse black holes without a strong ultraviolet background
Authors: Visbal Eli , Haiman Zoltán , Bryan Greg L.
Published: June 2014

Explaining the existence of supermassive black holes larger than ∼109 M⊙ at redshifts z ≳ 6 remains an open theoretical question. One possibility is that gas collapsing rapidly in pristine atomic cooling haloes (Tvir ≳ 104 K) produces 104–106 M⊙ black holes. Previous studies have shown that the formation of such a black hole requires a strong UV background to prevent molecular hydrogen cooling and gas fragmentation. Recently, it has been proposed that a high UV background may not be required for haloes that accrete material extremely rapidly or for haloes where gas cooling is delayed due to a high baryon-dark matter streaming velocity. In this work, we point out that building up a halo with Tvir ≳ 104 K before molecular cooling becomes efficient is not sufficient for forming a direct collapse black hole (DCBH). Though molecular hydrogen formation may be delayed, it will eventually form at high densities leading to efficient cooling and fragmentation. The only obvious way that molecular cooling could be avoided in the absence of strong UV radiation, is for gas to reach high enough density to cause collisional dissociation of molecular hydrogen (∼104 cm−3) before cooling occurs. However, we argue that the minimum core entropy, set by the entropy of the intergalactic medium when it decouples from the cosmic microwave background, prevents this from occurring for realistic halo masses. This is confirmed by hydrodynamical cosmological simulations without radiative cooling. We explain the maximum density versus halo mass in these simulations with simple entropy arguments. The low densities found suggest that DCBH formation indeed requires a strong UV background.
Overconsumption, outflows and the quenching of satellite galaxies
Authors: McGee Sean L. , Bower Richard G. , Balogh Michael L.
Published: June 2014

The baryon cycle of galaxies is a dynamic process involving the intake, consumption and ejection of vast quantities of gas. In contrast, the conventional picture of satellite galaxies has them methodically turning a large gas reservoir into stars until this reservoir is forcibly removed due to external ram pressure. This picture needs revision. Our modern understanding of the baryon cycle suggests that in some regimes the simple interruption of the fresh gas supply may quench satellite galaxies long before stripping events occur, a process we call overconsumption. We compile measurements from the literature of observed satellite quenching times at a range of redshifts to determine if satellites are principally quenched through orbit-based gas stripping events – either direct stripping of the disc (ram pressure stripping) or the extended gas halo (strangulation) – or from internally driven star formation outflows via overconsumption. These time-scales show significant deviations from the evolution expected for gas stripping mechanisms and suggest that either ram pressure stripping is much more efficient at high redshift, or that secular outflows quench satellites before orbit-based stripping occurs. Given the strong redshift evolution of star formation rates, at high redshift even moderate outflow rates will lead to extremely short delay times with the expectation that high-redshift (z > 1.5) satellites will be quenched almost immediately following the cessation of cosmological inflow. Observations of high-redshift satellites give an indirect but sensitive measure of the outflow rate, with current measurements suggesting that outflows are no larger than 2.5 times the star formation rate for galaxies with a stellar mass of 1010.5 M⊙.
Probing intergalactic neutral hydrogen by the Lyman alpha red damping wing of gamma-ray burst 130606A afterglow spectrum at z = 5.913
Authors: Totani Tomonori , Aoki Kentaro , Hattori Takashi , Kosugi George , Niino Yuu , Hashimoto Tetsuya , Kawai Nobuyuki , Ohta Kouji , Sakamoto Takanori , Yamada Toru
Published: June 2014

The unprecedentedly bright optical afterglow of GRB 130606A located by Swift at a redshift close to the reionization era (z = 5.913) provides a new opportunity to probe the ionization status of the intergalactic medium (IGM). Here we present an analysis of the red Lyα damping wing of the afterglow spectrum taken by Subaru/FOCAS during 10.4–13.2 hr after the burst. We find that the minimal model including only the baseline power-law and H i absorption in the host galaxy does not give a good fit, leaving residuals showing concave curvature in 8400–8900 Å with an amplitude of about 0.6% of the flux. Such a curvature in the short wavelength range cannot be explained either by extinction at the host with standard extinction curves, intrinsic curvature of afterglow spectra, or by the known systematic uncertainties in the observed spectrum. The red damping wing by intervening H i gas outside the host can reduce the residual by about 3 σ statistical significance. We find that a damped Lyα system is not favored as the origin of this intervening H i absorption, from the observed Lyβ and metal absorption features. Therefore absorption by diffuse IGM remains as a plausible explanation. A fit by a simple uniform IGM model requires an H i neutral fraction of fH i ∼ 0.1–0.5 depending on the distance to the GRB host, implying high fH i IGM associated with the observed dark Gunn–Peterson (GP) troughs. This gives new evidence that the reionization is not yet complete at z = 6.
Learning Through Noticing: Theory and Evidence from a Field Experiment
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Authors: Hanna Rema , Mullainathan Sendhil , Schwartzstein Joshua
Published: June 2014

We consider a model of technological learning under which people “learn through noticing”: they choose which input dimensions to attend to and subsequently learn about from available data. Using this model, we show how people with a great deal of experience may persistently be off the production frontier because they fail to notice important features of the data they possess. We also develop predictions on when these learning failures are likely to occur, as well as on the types of interventions that can help people learn. We test the model’s predictions in a field experiment with seaweed farmers. The survey data reveal that these farmers do not attend to pod size, a particular input dimension. Experimental trials suggest that farmers are particularly far from optimizing this dimension. Furthermore, consistent with the model, we find that simply having access to the experimental data does not induce learning. Instead, behavioral changes occur only after the farmers are presented with summaries that highlight previously unattended-to relationships in the data.
Temperature Resistance of Xylanase Inhibitors and the Presence of Grain‐Associated Xylanases Affect the Activity of Exogenous Xylanases Added to Pelleted Wheat‐Based Feeds
Authors: Smeets Natasja , Nuyens Filip , Niewold Theo , Van Campenhout Leen
Published: June 2014

The addition of exogenous xylanases (EX‐XYL) to wheat‐based poultry feeds is a common practice today. Wheat contains xylanase inhibitors (XI) and grain‐associated xylanases (GA‐XYL), which could affect the action of the EX‐XYL. In this study, both GA‐XYL and XI activity in feeding‐quality wheat were assessed. In addition, the effect of the conditions during digestion in monogastrics and the effects of pelleting at different conditioning temperatures on GA‐XYL and XI were investigated. The GA‐XYL activity varied between no activity and 0.821 XU/g. In contrast, the XI activity was consistently high in all wheat samples and ranged between 259 and 331 IU/g. Simulating the digestive process did not affect the activities of GA‐XYL or XI. Pelleting at 85°C or higher reduced the XI activity up to 46%. GA‐XYL, however, were more heat‐sensitive, and their activity was reduced to 67% at 60°C. The extract viscosity increased and the release of reducing sugars decreased at higher conditioning temperatures. In addition, the net effect of EX‐XYL on extract viscosity increased at higher temperatures, whereas the release of reducing sugars was not affected. In conclusion, XI affected the action of EX‐XYL during the digestive process, and pelleting did not eliminate their negative effects.
The Effect of Open-Ended High Tunnels in Western Washington on Late Blight and Physiological Leaf Roll Among Five Tomato Cultivars
Authors: Powell M. , Gundersen B. , Cowan J. , Miles C. A. , Inglis D. A.
Published: June 2014

A 3-year study in western Washington from 2010 to 2012 evaluated five tomato cultivars for tomato disease development and yield in open-ended high-tunnel versus open-field settings. Findings in 2010 revealed that severity of late blight, caused by Phytophthora infestans (US-11), was significantly (P = 0.002) lower in high-tunnel compared with open-field experimental plots based on area under disease progress curve (AUDPC) values of 0.02 versus 321, respectively. In spite of rescue foliar fungicide applications to open-field plots in 2011 and 2012, the mean number of late blight infections across cultivars was 1.8 to 30.8 compared with only 0 to 6.5 in high tunnels for these years. Furthermore, accumulated hours of leaf wetness were fewer in high tunnels than the open field each year (857 versus 1,060 in 2010, 598 versus 998 in 2011, and 885 versus 923 in 2012). Cultivar susceptibility to late blight could not be differentiated in high tunnels due to low disease pressure. However, all five cultivars proved susceptible in the open field, with ‘Oregon Spring’ consistently having the most lesions. In contrast, high-tunnel production contributed to an increased severity of physiological leaf roll compared with open-field production each year, and these values differed significantly (P = 0.0335 and 0.0252) in 2011 and 2012, respectively. AUDPC values for physiological leaf roll showed that Oregon Spring was significantly (P = <0.0001) less susceptible than other cultivars each year. Physiological leaf roll correlated positively (r values of 0.758 to 0. 960) and significantly (P < 0.05) with leaf wetness and air temperature in all years in both high-tunnel and open-field settings but the same was not true for relative humidity. Even with severe physiological leaf roll, high-tunnel production in 2010 resulted in significantly (P < 0.0001) greater total tomato yield than open-field production (35.0 versus 10.6 t ha−1). Although a significant interaction between production system and cultivar occurred in 2011 and 2012, tomato yield always was greater in high-tunnel than open-field plots. Open-ended high tunnels offer tomato growers a potential tool for managing late blight in western Washington while also increasing yield, and could be especially useful in organic production.