bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparing the Minimum Income Standard in the UK and Japan: Methodology and Outcome
Authors: Davis Abigail , Hirsch Donald , Iwanaga Rie , Iwata Masami , Shigekawa Junko , Uzuki Yuka , Yamada Atsuhiro
Published: July 2013

Minimum Income Standard (MIS) research involves an innovative methodology that combines consensual decisions made through discussion by members of the public, supported by input from experts. MIS addresses questions about income adequacy, and in particular, what is the income that people need in order to reach a minimum socially acceptable standard of living. The first MIS for Britain was published in the UK in 2008, and in 2010 researchers from Japan and the UK began to collaborate on developing a comparable Minimum Income Standard for Japan. This article discusses the differences and similarities between the UK and Japanese MIS. It looks at the challenges of applying the methodology in a very different setting and compares the results of the research in the UK and in Japan. Although there are notable differences in the lists of goods and services that comprise the budgets, there are also some striking similarities. This research suggests that the MIS methodology offers an approach that can be used in different countries to inform discussions on contemporary living standards and societal norms, and to enable international comparisons to be drawn.
Diffusion Models in Experimental Psychology
Authors: Voss Andreas , Nagler Markus , Lerche Veronika
Published: July 2013

Stochastic diffusion models ( Ratcliff, 1978 ) can be used to analyze response time data from binary decision tasks. They provide detailed information about cognitive processes underlying the performance in such tasks. Most importantly, different parameters are estimated from the response time distributions of correct responses and errors that map (1) the speed of information uptake, (2) the amount of information used to make a decision, (3) possible decision biases, and (4) the duration of nondecisional processes. Although this kind of model can be applied to many experimental paradigms and provides much more insight than the analysis of mean response times can, it is still rarely used in cognitive psychology. In the present paper, we provide comprehensive information on the theory of the diffusion model, as well as on practical issues that have to be considered for implementing the model.
The phosphatidylinositol‐transfer protein Nir2 binds phosphatidic acid and positively regulates phosphoinositide signalling
Authors: Kim SoHui , Kedan Amir , Marom Merav , Gavert Nancy , Keinan Omer , Selitrennik Michael , Laufman Orly , Lev Sima
Published: July 2013

Phosphatidic acid (PA) and phosphoinositides are metabolically interconverted lipid second messengers that have central roles in many growth factor (GF)‐stimulated signalling pathways. Yet, little is known about the mechanisms that coordinate their production and downstream signalling. Here we show that the phosphatidylinositol (PI)‐transfer protein Nir2 translocates from the Golgi complex to the plasma membrane in response to GF stimulation. This translocation is triggered by PA formation and is mediated by its C‐terminal region that binds PA in vitro. We further show that depletion of Nir2 substantially reduces the PI(4,5)P2 levels at the plasma membrane and concomitantly GF‐stimulated PI(3,4,5)P3 production. Finally, we show that Nir2 positively regulates the MAPK and PI3K/AKT pathways. We propose that Nir2 through its PA‐binding capability and PI‐transfer activity can couple PA to phosphoinositide signalling, and possibly coordinates their local lipid metabolism and downstream signalling.
CD49b‐dependent establishment of T helper cell memory
Authors: Hanazawa Asami , Hayashizaki Koji , Shinoda Kenta , Yagita Hideo , Okumura Ko , Löhning Max , Hara Takahiro , Tani‐ichi Shizue , Ikuta Koichi , Eckes Beate , Radbruch Andreas , Tokoyoda Koji , Nakayama Toshinori
Published: July 2013

CD4 T cells play a key role in immunological memory. We have demonstrated that professional memory CD4 T cells reside and rest in the bone marrow (BM). However, the molecular mechanisms of their establishment in the BM and their maintenance remain unclear. We here show that memory CD4 T cells express high levels of CD49b and that CD49b‐deficient or ‐blocked memory CD4 T‐cell precursors fail to migrate from blood into the marrow of the bone, and they especially fail to transmigrate through sinusoidal endothelial cells of the BM. In the marrow, memory CD4 T cells and the precursors contact stromal cells expressing collagen II that are specific ligands for CD49b. Interestingly, memory CD4 T cells on day 117 of an immune response also dock on IL‐7+/collagen XI+ stromal cells, whereas memory precursors on day 12 do not. These results indicate that the collagen receptor CD49b is required for the migration of memory CD4 T‐cell precursors into their survival niches of the bone marrow.
MicroRNA‐146a and RBM4 form a negative feed‐forward loop that disrupts cytokine mRNA translation following TLR4 responses in human THP‐1 monocytes
Authors: Brudecki Laura , Ferguson Donald A , McCall Charles E , El Gazzar Mohamed
Published: July 2013

Within hours after its initiation, the severe systemic inflammatory response of sepsis shifts to an adaptive anti‐inflammatory state with coincident immunosuppression. This anti‐inflammatory phenotype is characterized by diminished proinflammatory cytokine gene expression in response to toll‐like receptor (TLR) stimulation with bacterial endotoxin/lipopolysaccharide (LPS), also known as endotoxin tolerance/adaptation. Our and other studies have established that gene‐specific reprogramming following TLR4 responses independently represses transcription and translation of proinflammatory genes such as tumor necrosis factor alpha (TNFα). We also previously demonstrated that TNFα and interleukin (IL)‐6 mRNA translation is repressed in endotoxin‐adapted THP‐1 human monocytes by an miRNA‐based mechanism involving the argonaute family protein argonaute 2 (Ago2). Here, we further define the molecular nature of reprogramming translation by showing that TLR4‐induced microRNA‐146 promotes a feed‐forward loop that modifies the subcellular localization of the RNA‐binding protein RBM4 (RNA‐binding motif protein 4) and promotes its interaction with Ago2. This interaction results in the assembly of a translation‐repressor complex that disrupts TNFα and IL‐6 cytokine synthesis in endotoxin‐adapted THP‐1 monocytes. This novel molecular path prevents the phosphorylation of RBM4 on serine‐309 by p38 MAPK (mitogen‐activated protein kinase), which leads to RBM4 accumulation in the cytosol and interaction with Ago2. We further find that microRNA‐146a knockdown by antagomirs or protein phosphatase inhibition by okadaic acid increases p38 MAPK phosphorylation and results in RBM4 serine‐309 phosphorylation and nuclear relocalization, which disrupts RBM4 and Ago2 interactions and restores TLR4‐dependent synthesis of TNFα and IL‐6. We conclude that miR‐146a has a diverse and critical role in limiting an excessive acute inflammatory reaction.
Towards a better understanding of the novel avian-origin H7N9 influenza A virus in China
Authors: Wang Yongbo , Dai Zhangyan , Cheng Han , Liu Zexian , Pan Zhicheng , Deng Wankun , Gao Tianshun , Li Xiaotong , Yao Yuangen , Ren Jian , Xue Yu
Published: July 2013

Recently, a highly dangerous bird flu has infected over 130 patients in China and the outbreak was attributed to a novel avian-origin H7N9 virus. Here, we performed a systematic analysis of the virus. We clarified the controversial viewpoint on neuraminidase (NA) origin and confirmed it was reassorted from Korean wild birds with higher confidence, whereas common ancestors of pathogenic H7N9 genes existed only one or two years ago. Further analysis of NA sequences suggested that most variations are not drug resistant and current drugs are still effective for the therapy. We also identified a potentially optimal 9-mer epitope, which can be helpful for vaccine development. The interaction of hemagglutinin (HA) and human receptor analog was confirmed by structural modeling, while NA might influence cellular processes through a PDZ-binding motif. A simplified virus infection model was proposed. Taken together, our studies provide a better understanding of the newly reassorted H7N9 viruses.
Combining surface topography with polymer chemistry: exploring new interfacial biological phenomena
Authors: Li Dan , Zheng Qing , Wang Yanwei , Chen Hong
Published: July 2013

This review focuses on combining surface topography and surface chemical modification by the grafting of polymers to develop optimal material interfaces with synergistic properties and functions for biological and biomedical applications.
Efficient switching scheme using multiple shared memories
Authors: Choi Ick‐Sung , Kwark Gwang‐Hoon , Choi Hyung‐Rim , Yang Jae‐Woo , Kang Dae‐Sung
Published: July 2013

A novel switching scheme using multiple shared memories is proposed. It has low implementation complexity and ideal performance for both uniform traffic and non‐uniform traffic without speedup. The proposed algorithm assigns an output time for each incoming data according to its destination and distributes them into 2N shared memories that can be addressable by output time, where N is the number of input/output ports. Experimental results show that the proposed scheme has good performance for both uniform traffic and non‐uniform traffic.
High‐isolation switchable bandpass filter using connected‐coupling line
Authors: Chao Shih‐Fong , Lin Wei‐Cheng
Published: July 2013

A new switchable bandpass filter using switchable connected‐coupling lines (SCCLs) is presented. The SCCL is embedded in a bandpass filter and treated as an admittance inverter to provide adequate coupling coefficient to form a bandpass response in an on state. The passband of the bandpass filter is centerd at 1.5 GHz with 12.8% 3‐dB fractional bandwidth. In the off state, the switchable line acts as a travelling‐wave switch to cut off the coupling path to achieve a high isolation. The measured isolation of the circuit is greater than 48 dB over the operating bandwidth.
Compact 3–11 GHz UWB planar unequal power divider using two‐section asymmetric coupled transmission lines and non‐uniform microstrip
Authors: Wu Y. , Liu Y.
Published: July 2013

A compact upper wideband unequal power divider with planar configuration is proposed. This power divider includes two‐section asymmetric coupled transmission lines and non‐uniform microstrip. The measured results of the prototype divider show that the 12.1 dB return loss and ports‐isolation band is in the range from 3.1 to 10.6 GHz, the unequal power division coefficient is almost in the range 4.03–5 dB (the simulated result: 4.3–4.75 dB).
Power‐efficient, PVT robust conductance cancellation method for gain enhancement
Authors: Huang B. , Chen D.
Published: July 2013

A power‐efficient, process, voltage and temperature (PVT) robust gds cancellation method for gain enhancement is proposed. The method generates a negative conductance, which matches and cancels the positive conductance. This makes the gds cancellation method effective over process and wide temperature variation without the aid of external calibration or a tuning circuit. The method senses signals from cascode nodes instead of output nodes, making the method insensitive to output voltage swing. The simulation results of an example implementation in IBM 0.13 µm process show at least 22 dB DC gain enhancement over all process corners and temperatures ranging from − 20 to 80°C, with less than 9% power consumption overhead.
Passive orientation measurement using magnetoquasistatic fields and coupled magnetic resonances
Authors: Arumugam D.D. , Ricketts D.S.
Published: July 2013

A passive position orientation measurement method is presented which leverages the spatial variation of the reflected magnetoquasistatic field from a mobile loop to determine the loop's spatial orientation. The azimuthal orientation was measured from 0° to 360° at a distance of 1 m from the fixed measurement loop. Inverting the theoretical expressions to estimate orientation from measured field values resulted in an average and RMS error of 3.15° and 4.55°, respectively. This technique offers a means to accurately determine the orientation of the mobile loop through purely passive methods.
High field‐effect mobility amorphous InSnZnO thin‐film transistors with low carrier concentration and oxygen vacancy
Authors: Jang K. , Raja J. , Kim J. , Lee Y. , Kim D. , Yi J.
Published: July 2013

The influence of carrier concentration and oxygen vacancy on the performance of amorphous‐indium–tin–zinc‐oxide (a‐ITZO) thin‐film transistors (TFTs) is reported. The ITZO TFT with lowest carrier concentration and oxygen vacancy has a high field‐effect mobility (μFE) of 37.2 cm2/V•s, a high on/off current ratio (ION/IOFF) of ∼1 × 107 and a low subthreshold swing (SS) of 0.93 V/decade. By increasing the carrier concentration and oxygen vacancy, μFE, ION/OFF and SS were surprisingly degraded to 14.4 cm2/V•s, ∼4 × 104 and 4.01 V/decade, respectively. By controlling the carrier concentration and oxygen vacancies of ITZO bulk, improvement of the performance in TFT devices can be achieved. The proposed high μFE of 37.2 cm2/V•s is enough for the application of next‐generation displays requiring ultra‐high resolution and high‐frame‐rate displays.
Three‐dimensional high‐speed optical coherence tomography system using KTN swept light source
Authors: Okabe Y. , Ueno M. , Sasaki Y. , Sakamoto T. , Toyoda S. , Kobayashi J. , Sugawa Y. , Fukuda A. , Ohmi M.
Published: July 2013

Three‐dimensional (3D) optical coherence tomography (3D‐OCT) has attracted attention for visualising complex structures in the biomedical field. In this reported work, a high‐speed 3D‐OCT system is developed, which is based on a high‐speed swept light source and a Mach‐Zehnder interferometer with a high‐speed photodetector. The light source, incorporating a KTa1–xNbxO3 electro‐optic deflector, operates at a repetition rate of 200 kHz and enables high‐speed data acquisition. As a preliminary study, images of a strawberry's surface have been obtained, two‐ and three‐dimensionally. The 3D‐OCT system has potential for the construction of a four‐dimensional OCT image to dynamically display 3D‐OCT images.
60 GHz dual‐band bandpass filter using LTCC
Authors: Xu Xin , Wang Jianpeng , Zhang Gang
Published: July 2013

A dual‐band bandpass filter with quasi‐elliptic response using a substrate integrated waveguide for 60 GHz dual‐band wireless communication systems is proposed. It is fabricated with standard low‐temperature co‐fired ceramic (LTCC) technology. The measured results indicate that the filter is operating at 59.78 and 61.56 GHz with fractional bandwidths of 2.1 and 2.2%, and minimum in‐band insertion losses of 3.61 and 3.55 dB, respectively. Furthermore, the proposed filter exhibits an electrical size (including the CPW measurement pads) of 2.38λg × 3.14λg, where λg is the guided wavelength at 60 GHz.
Compact tunable bandpass filter with wide tuning range and enhanced stopband characteristics
Authors: Zhao B.L. , He Z.T. , Wei X.B. , Shi Y.
Published: July 2013

A compact tunable bandpass filter (BPF) with wide tuning range and enhanced stopband characteristics based on low‐temperature co‐fired ceramic technique is proposed. The wide tuning range is realised by properly introducing an axial coupling structure. Three transmission zeros are obtained near the passband for enhanced frequency selectivity by introducing mixed electric/magnetic (E/M) coupling between the source/load and the taped inductor. Back‐to‐back varactor diodes are adopted to improve linearity characteristics. A tunable BPF with a 120% tuning range from 370 to 850 MHz has been designed and fabricated to verify the proposed design concept. The measured results are in good agreement with the electromagnetic simulation. The circuit occupies only 4.0 × 3.0 × 1.6 mm3.
High RF performance improvement using surface passivation technique of AlGaN/GaN HEMTs at K‐band application
Authors: Lee B.H. , Kim R.H. , Lim B.O. , Choi G.W. , Kim H.J. , Hong I.P. , Lee J.H.
Published: July 2013

A surface passivation technique of high electron mobility transistor (HEMT) devices is reported. The passivated HEMT device has a much higher RF performance of FT and Fmax than a non‐passivated one. The AlGaN/GaN HEMT has a short gate length of 0.15 µm using an E‐beam lithography system and very low ohmic contact resistance of 1.3 × 10−6 Ωcm−2 using a rapid thermal processing alloy system. In addition, to protect the active layer from the surface trap, an SiO2 thin film passivation process is applied by the plasma‐enhanced chemical vapour deposition system. The fabricated AlGaN/GaN HEMT exhibits a maximum drain current of 900 mA/mm and a maximum transconductance of 320 mS/mm. In particular, this device produces excellent RF performance of small‐signal characteristics, such as a current gain cut‐off frequency (fT) of 55 GHz and maximum oscillation frequencies (fmax) of 130 GHz.
Flat super‐continuum generation using carbon‐nanotube‐based modelocked laser and normal dispersion photonic crystal fibre
Authors: Liu H.H. , Chow K.K.
Published: July 2013

A flat super‐continuum (SC) generated by a 1.5 µm passively fibre modelocked laser incorporating a single‐walled carbon‐nanotube‐based saturable absorber and a normal dispersion highly nonlinear photonic crystal fibre (PCF) is demonstrated. A compressed 620 fs pulse train from the modelocked laser is obtained and launched into the PCF. Since the pulses propagate in the normal dispersion regime of the PCF, linear frequency chirp is induced by self‐phase modulation which leads to a flat SC. An SC covering 200 nm with less than 7 dB power fluctuation is achieved. The experimental results are consistent with the theoretical analysis based on the nonlinear Schrödinger equation.
Application of amplitude transformation for compensation of comb decimation filters
Authors: Romero D.E.T. , Dolecek G. J.
Published: July 2013

The design of compensation filters for comb decimators using amplitude transformation is introduced. It is shown that the transformation of cosine‐squared filters provides good compensation characteristics. For a first‐degree polynomial, the slope of the transformation line is explicitly set as the unique compensator's multiplierless coefficient. This coefficient changes proportionally with the increase of the comb passband droop. Thus, the proposed approach provides an intuitive and easy way of designing compensation filters.
Metasurface‐loaded circularly‐polarised slot antenna with high front‐to‐back ratio
Authors: Chung K.L. , Kharkovsky S.
Published: July 2013

A new technique to achieve high front‐to‐back radiation ratios of slot antennas is presented. A 0.8 mm thin metasurface is loaded onto a circularly‐polarised slot antenna and backed by a metallic reflector at close distances. The antenna has an overall height of ∼ 0.1 wavelengths. However, it exhibits wideband characteristics with a measured impedance bandwidth (voltage standing‐wave ratio ≤ 2) of 73.3% and a 3 dB axial‐ratio bandwidth of 29.1%. A broadside gain of 7 dBic with a front‐to‐back ratio of 23.7 dB is achieved at 2.7 GHz.
Yield‐driven design of tunnelling SRAM cells
Authors: Zuo D. , Kelly M.J.
Published: July 2013

As an implementation of the static random access memory (SRAM), the tunnelling SRAM (TSRAM) uses the negative differential resistance of resonant (interband) tunnelling diodes (R(I)TDs) and potentially offers improved standby power dissipation and integration density compared with the conventional CMOS SRAM. TSRAM has not yet been realised with a useful bit capacity mainly because the level of reproducibility required of the nanoscale R(I)TDs has been demanding and difficult to achieve. In this reported work, the design of TSRAM cells is approached from the perspective of maximising their yield and specific results are presented for an RITD‐based cell. With advances in the control of semiconductor multilayer growth, it is shown that achieving acceptable yields is now within sight.
Reception of longitudinal vector potential radiation with a plasma antenna
Authors: Zimmerman Robert K.
Published: July 2013

To help resolve the long-running debate between physicists and engineers regarding the existence of the magnetic vector potential, herewith we describe an experiment demonstrating reception of time-harmonic vector potential radiation at 1.3 GHz.
Adsorption of hydrogen on the surface and sub-surface of Cu(111)
Authors: Mudiyanselage Kumudu , Yang Yixiong , Hoffmann Friedrich M. , Furlong Octavio J. , Hrbek Jan , White Michael G. , Liu Ping , Stacchiola Darío J.
Published: July 2013

The interaction of atomic hydrogen with the Cu(111) surface was studied by a combined experimental-theoretical approach, using infrared reflection absorption spectroscopy, temperature programmed desorption, and density functional theory (DFT). Adsorption of atomic hydrogen at 160 K is characterized by an anti-absorption mode at 754 cm−1 and a broadband absorption in the IRRA spectra, related to adsorption of hydrogen on three-fold hollow surface sites and sub-surface sites, and the appearance of a sharp vibrational band at 1151 cm−1 at high coverage, which is also associated with hydrogen adsorption on the surface. Annealing the hydrogen covered surface up to 200 K results in the disappearance of this vibrational band. Thermal desorption is characterized by a single feature at ∼295 K, with the leading edge at ∼250 K. The disappearance of the sharp Cu-H vibrational band suggests that with increasing temperature the surface hydrogen migrates to sub-surface sites prior to desorption from the surface. The presence of sub-surface hydrogen after annealing to 200 K is further demonstrated by using CO as a surface probe. Changes in the Cu-H vibration intensity are observed when cooling the adsorbed hydrogen at 180 K to 110 K, implying the migration of hydrogen. DFT calculations show that the most stable position for hydrogen adsorption on Cu(111) is on hollow surface sites, but that hydrogen can be trapped in the second sub-surface layer.
Vapor transport deposition and epitaxy of orthorhombic SnS on glass and NaCl substrates
Authors: Wangperawong Artit , Herron Steven M. , Runser Rory R. , Hägglund Carl , Tanskanen Jukka T. , Lee Han-Bo-Ram , Clemens Bruce M. , Bent Stacey F.
Published: July 2013

Polycrystalline SnS, Sn2S3, and SnS2 were deposited onto glass substrates by vapor transport deposition, with the stoichiometry controlled by deposition temperature. In addition, epitaxial growth of orthorhombic SnS(010) films on NaCl(100) with thicknesses up to 600 nm was demonstrated. The in-plane [100] directions of SnS and NaCl are oriented approximately 45° apart, and the translational relationship between SnS and NaCl was predicted by density functional theory. The epitaxial SnS is p-type with carrier concentration on the order of 1017 cm−3 and Hall hole mobility of 385 cm2 V−1 s−1 in-plane. It has indirect and direct bandgaps of 1.0 and 2.3 eV, respectively.
Cloaking and magnifying using radial anisotropy
Authors: Kettunen Henrik , Wallén Henrik , Sihvola Ari
Published: July 2013

This paper studies the electrostatic responses of a polarly radially anisotropic cylinder and a spherically radially anisotropic sphere. For both geometries, the permittivity components differ from each other in the radial and tangential directions. We show that choosing the ratio between these components in a certain way, these rather simple structures can be used in cloaking dielectric inclusions with arbitrary permittivity and shape in the quasi-static limit. For an ideal cloak, the contrast between the permittivity components has to tend to infinity. However, only positive permittivity values are required and a notable cloaking effect can already be observed with relatively moderate permittivity contrasts. Furthermore, we show that the polarly anisotropic cylindrical shell has a complementary capability of magnifying the response of an inner cylinder.
A primitive kinetic-fluid model for quasi-parallel propagating magnetohydrodynamic waves
Authors: Nariyuki Y. , Saito S. , Umeda T.
Published: July 2013

The extension and limitation of the existing one-dimensional kinetic-fluid model (Vlasov-MHD (magnetohydrodynamic) model), which has been used to analyze parametric instabilities of parallel propagating Alfvén waves, are discussed. The inconsistency among the given velocity distribution functions in the past studies is resolved through the systematic derivation of the multi-dimensional Vlasov-MHD model. The linear dispersion analysis of the present model indicates that the collisionless damping of the slow modes is adequately evaluated in low beta plasmas, although the deviation between the present model and the full-Vlasov theory increases with increasing plasma beta and increasing propagation angle. This is because the transit-time damping is not correctly evaluated in the present model. It is also shown that the ponderomotive density fluctuations associated with the envelope-modulated quasi-parallel propagating Alfvén waves derived from the present model is not consistent with those derived from the other models such as the Landau-fluid model, except for low beta plasmas. The result indicates the present model would be useful to understand the linear and nonlinear development of the Alfvénic turbulence in the inner heliosphere, whose condition is relatively low beta, while the existing model and the present model are insufficient to discuss the parametric instabilities of Alfvén waves in high beta plasmas and the obliquely propagating waves.
Magnetoresistance in InMnAs/InAs heterojunctions and its dependence on alloy composition and temperature
Authors: Peters J. A. , Garcia C. , Wessels B. W.
Published: July 2013

We report on the effect of alloy composition and temperature on the large positive magnetoresistance of p-In1−xMnxAs/n-InAs dilute magnetic semiconductor heterojunctions. The junction magnetoconductance with magnetic field and current parallel is well-described by an analytical expression for the total conductance Gtot of two spin split bands. From the junction, magnetoconductance an effective g-factor, due to a large Zeeman effect, was determined for varying Mn concentration. The effective g-factor increases with increasing Mn concentration from 98 to 131 for xMn = 0.01 to xMn = 0.06. There is an excellent agreement between the calculated curve for the g-factor and the experimentally derived values.
Conduction and electric field effect in ultra-thin TiN films
Authors: Van Bui Hao , Kovalgin Alexey Y. , Schmitz Jurriaan , Wolters Rob A. M.
Published: July 2013

Using low pressure atomic layer deposition, ultra-thin continuous TiN films were prepared. The temperature coefficient of resistance (TCR), resistivity and field effect properties of these films were investigated. With decreasing film thickness, a positive-to-negative transition of TCR and a steep increase of resistivity were observed. This is attributed to the metal-semimetal transition of the TiN films. We demonstrate appreciable field-induced current modulation up to 11% in a 0.65 nm TiN film. The field effect is remarkably independent of temperature. A polarity asymmetry of the current-voltage characteristics is found, attributed to the interplay between different types of the carriers.
Enhanced thermopower and thermoelectric performance through energy filtering of carriers in (Bi2Te3)0.2(Sb2Te3)0.8 bulk alloy embedded with amorphous SiO2 nanoparticles
Authors: Dou Y. C. , Qin X. Y. , Li D. , Li L. L. , Zou T. H. , Wang Q. Q.
Published: July 2013

(Bi2Te3)0.2(Sb2Te3)0.8 (BST) based nanocomposites dispersed with amorphous SiO2 (a-SiO2) nanoparticles (∼50 nm) were fabricated and their thermoelectric properties were investigated in the temperature range from 293 K to 490 K. The results indicate that with increasing volume fraction of a-SiO2 from f = 0 to 0.55, 1.10, and then to 2.20 vol. %, the electrical resistivity ρ of the nanocomposites f(a-SiO2)/BST decreases first (f = 0.55 vol. %) and then increases rapidly with further increasing a-SiO2 content, which is proved to be caused mainly by changes of carrier concentration. In contrast, Seebeck coefficient S for the nanocomposites increases monotonically with increase in f, specially at T < ∼380 K, suggesting that at low a-SiO2 (f = 0.55 vol. %) content, at least, the increase in S of the nanocomposite could be ascribed to energy filtering effect arising from enhanced carrier scattering by the interface potentials due to the embedded a-SiO2 nanoparticles. Owing to both increased power factor (S2/ρ) and reduced thermal conductivity caused by phonon scattering of nanoparticles as well as phase boundaries, the dimensionless figure of merit ZT of f(a-SiO2)/BST composite sample with f = 0.55 vol. % enhanced substantially at T < 390 K; specifically, ZT of the composite sample reaches 1.12 and 1.27 at ∼303 K and ∼363 K, respectively, which is, respectively, ∼27% and ∼20% larger than that (0.88 and 1.06) of BST, demonstrating that thermoelectric performance of BST can be effectively elevated by incorporation of a-SiO2 nanoparticles.
Improvements in thermionic cooling through engineering of the heterostructure interface using Monte Carlo simulations
Authors: Stephen A. , Dunn G. M. , Oxley C. H. , Glover J. , Montes Bajo M. , Cumming D. R. S. , Khalid A. , Kuball M.
Published: July 2013

A self-consistent Ensemble Monte Carlo (EMC) model was developed to simulate the thermionic effect in heterostructure barrier coolers. The model was validated on an InGaAs-InGaAsP heterostructure device of variable barrier height and width, producing good quantitative agreement with previous literature results. The operation of the cooler was found to be a complex and intricate process depending on the field, conduction band and details of barrier structure. When applied to a GaAs-AlGaAs micro-cooler there was good agreement with the experimental results. Importantly, very small alterations in the barrier structure were found to lead to considerable changes in device performance.
All-electrical spin injection and detection in the Co2FeSi/GaAs hybrid system in the local and non-local configuration
Authors: Bruski P. , Manzke Y. , Farshchi R. , Brandt O. , Herfort J. , Ramsteiner M.
Published: July 2013

We demonstrate the electrical injection and detection of spin-polarized electrons in the Co2FeSi/GaAs hybrid system using lateral transport structures. Spin valve signatures and characteristic Hanle curves are observed both in the non-local and the local configuration. The comparatively large magnitude of the local spin valve signal and the high signal-to-noise ratio are attributed to the large spin polarization at the Fermi energy of Co2FeSi in the well-ordered L21 phase.
Surface-mode enhanced photonic-crystal nano-imaging observed by a scanning near-field optical microscope
Authors: Zhang Qiming , Li Xiangping , Gu Min
Published: July 2013

In this paper, we experimentally demonstrate the sub-wavelength loss-less nano-imaging effect achieved by the surface-mode coupling in a negative refraction silicon photonic crystal at a wavelength of 1100 nm. The surface mode and nano-imaging effect of the photonic crystal are experimentally studied with a scanning near-field optical microscope. The thickness and the wavelength dependence of the full width at half maximum of the focal spot reveal a direct evidence of the surface-mode enhanced nano-imaging effect, which is consistent with the simulation. As a consequence, a focal spot with a lateral resolution of λ/3 at the predicted wavelength has been achieved.
Differential performance of two forage species, Medicago truncatula and Sulla carnosa, under water-deficit stress and recovery
Authors: Rouached Aida , Slama Inès , Zorrig Walid , Jdey Asma , Cukier Caroline , Rabhi Mokded , Talbi Ons , Limami Anis Mohamed , Abdelly Chedly
Published: July 2013

The response patterns during water deficit stress and subsequent recovery of two forage species, Medicago truncatula and Sulla carnosa, were studied. After germination and pre-treatment, seedlings were individually cultivated for two months under two irrigation modes: 100% and 33% of field capacity. Measured parameters were plant growth, water relations, leaf osmotic potential, lipid peroxidation, and leaf inorganic (Na+ and K+) and organic (proline and soluble sugars) solute contents, as well as delta-1-pyrroline-5-carboxylate synthase (P5CS) and proline dehydrogenase (PDH) activities. Our results showed that under control conditions, and in contrast to roots, no significant differences were observed in shoot biomass production between the two species. However, when subjected to water-deficit stress, M. truncatula appeared to be more tolerant than S. carnosa (reduction by 50 and 70%, respectively). In the two studied species, water-deficit stress led to an increase in root/shoot ratio and leaf proline and soluble sugar contents, and a decrease in leaf osmotic potential. Enzymatic assay revealed that in the two species, P5CS activity was stimulated whereas that of PDH was inhibited under stress conditions. Despite greater accumulation of proline, sugar, and potassium in leaves of S. carnosa, M. truncatula was more tolerant to water deficit. This was essentially due to its capacity to control tissue hydration and water-use efficiency, in addition to its greater ability to protect membrane integrity. Following stress relief, M. truncatula and S. carnosa showed partial re-establishment of growth capacity.
Hyperuniformity in amorphous silicon based on the measurement of the infinite-wavelength limit of the structure factor
Authors: Xie Ruobing , Long Gabrielle G. , Weigand Steven J. , Moss Simon C. , Carvalho Tobi , Roorda Sjoerd , Hejna Miroslav , Torquato Salvatore , Steinhardt Paul J.
Published: July 2013

We report the results of highly sensitive transmission X-ray scattering measurements performed at the Advanced Photon Source, Argonne National Laboratory, on nearly fully dense high-purity amorphous-silicon (a-Si) samples for the purpose of determining their degree of hyperuniformity. A perfectly hyperuniform structure has complete suppression of infinite-wavelength density fluctuations, or, equivalently, the structure factor
S
(
q
→0) = 0; the smaller the value of
S
(0), the higher the degree of hyperuniformity. Annealing was observed to increase the degree of hyperuniformity in a-Si where we found
S
(0) = 0.0075 (±0.0005), which is significantly below the computationally determined lower bound recently suggested by de Graff and Thorpe [de Graff AMR, Thorpe MF (2010)
Acta Crystallogr A
66(Pt 1):22–31] based on studies of continuous random network models, but consistent with the recently proposed nearly hyperuniform network picture of a-Si. Increasing hyperuniformity is correlated with narrowing of the first diffraction peak and extension of the range of oscillations in the pair distribution function.
Poststimulus undershoots in cerebral blood flow and BOLD fMRI responses are modulated by poststimulus neuronal activity
Authors: Mullinger Karen J. , Mayhew Stephen D. , Bagshaw Andrew P. , Bowtell Richard , Francis Susan T.
Published: July 2013

fMRI is the foremost technique for noninvasive measurement of human brain function. However, its utility is limited by an incomplete understanding of the relationship between neuronal activity and the hemodynamic response. Though the primary peak of the hemodynamic response is modulated by neuronal activity, the origin of the typically negative poststimulus signal is poorly understood and its amplitude assumed to covary with the primary response. We use simultaneous recordings of EEG with blood oxygenation level-dependent (BOLD) and cerebral blood flow (CBF) fMRI during unilateral median nerve stimulation to show that the poststimulus fMRI signal is neuronally modulated. We observe high spatial agreement between concurrent BOLD and CBF responses to median nerve stimulation, with primary signal increases in contralateral sensorimotor cortex and primary signal decreases in ipsilateral sensorimotor cortex. During the poststimulus period, the amplitude and directionality (positive/negative) of the BOLD signal in both contralateral and ipsilateral sensorimotor cortex depends on the poststimulus synchrony of 8–13 Hz EEG neuronal activity, which is often considered to reflect cortical inhibition, along with concordant changes in CBF and metabolism. Therefore we present conclusive evidence that the fMRI time course represents a hemodynamic signature of at least two distinct temporal phases of neuronal activity, substantially improving understanding of the origin of the BOLD response and increasing the potential measurements of brain function provided by fMRI. We suggest that the poststimulus EEG and fMRI responses may be required for the resetting of the entire sensory network to enable a return to resting-state activity levels.
Pinpointing genes underlying the quantitative trait loci for root-knot nematode resistance in palaeopolyploid soybean by whole genome resequencing
Authors: Xu Xiangyang , Zeng Liang , Tao Ye , Vuong Tri , Wan Jinrong , Boerma Roger , Noe Jim , Li Zenglu , Finnerty Steve , Pathan Safiullah M. , Shannon J. Grover , Nguyen Henry T.
Published: July 2013

The objective of this study was to use next-generation sequencing technologies to dissect quantitative trait loci (QTL) for southern root-knot nematode (RKN) resistance into individual genes in soybean. Two hundred forty-six recombinant inbred lines (RIL) derived from a cross between Magellan (susceptible) and PI 438489B (resistant) were evaluated for RKN resistance in a greenhouse and sequenced at an average of 0.19× depth. A sequence analysis pipeline was developed to identify and validate single-nucleotide polymorphisms (SNPs), infer the parental source of each SNP allele, and genotype the RIL population. Based on 109,273 phased SNPs, recombination events in RILs were identified, and a total of 3,509 bins and 3,489 recombination intervals were defined. About 50.8% of bins contain 1 to 10 genes. A linkage map was subsequently constructed by using bins as molecular markers. Three QTL for RKN resistance were identified. Of these, one major QTL was mapped to bin 10 of chromosome 10, which is 29.7 kb in size and harbors three true genes and two pseudogenes. Based on sequence variations and gene-expression analysis, the candidate genes underlying the major QTL for RKN resistance were pinpointed. They are Glyma10g02150 and Glyma10g02160, encoding a pectin methylesterase inhibitor and a pectin methylesterase inhibitor -pectin methylesterase, respectively. This QTL mapping approach not only combines SNP discovery, SNP validation, and genotyping, but also solves the issues caused by genome duplication and repetitive sequences. Hence, it can be widely used in crops with a reference genome to enhance QTL mapping accuracy.
On the origins of hierarchy in complex networks
Authors: Corominas-Murtra Bernat , Goñi Joaquín , Solé Ricard V. , Rodríguez-Caso Carlos
Published: July 2013

Hierarchy seems to pervade complexity in both living and artificial systems. Despite its relevance, no general theory that captures all features of hierarchy and its origins has been proposed yet. Here we present a formal approach resulting from the convergence of theoretical morphology and network theory that allows constructing a 3D morphospace of hierarchies and hence comparing the hierarchical organization of ecological, cellular, technological, and social networks. Embedded within large voids in the morphospace of all possible hierarchies, four major groups are identified. Two of them match the expected from random networks with similar connectivity, thus suggesting that nonadaptive factors are at work. Ecological and gene networks define the other two, indicating that their topological order is the result of functional constraints. These results are consistent with an exploration of the morphospace, using
in silico
evolved networks.
Polyglutamine domain flexibility mediates the proximity between flanking sequences in huntingtin
Authors: Caron Nicholas Stephane , Desmond Carly Robyn , Xia Jianrun , Truant Ray
Published: July 2013

Huntington disease (HD) is a neurodegenerative disorder caused by a CAG expansion within the huntingtin gene that encodes a polymorphic glutamine tract at the amino terminus of the huntingtin protein. HD is one of nine polyglutamine expansion diseases. The clinical threshold of polyglutamine expansion for HD is near 37 repeats, but the mechanism of this pathogenic length is poorly understood. Using Förster resonance energy transfer, we describe an intramolecular proximity between the N17 domain and the downstream polyproline region that flanks the polyglutamine tract of huntingtin. Our data support the hypothesis that the polyglutamine tract can act as a flexible domain, allowing the flanking domains to come into close spatial proximity. This flexibility is impaired with expanded polyglutamine tracts, and we can detect changes in huntingtin conformation at the pathogenic threshold for HD. Altering the structure of N17, either via phosphomimicry or with small molecules, also affects the proximity between the flanking domains. The structural capacity of N17 to fold back toward distal regions within huntingtin requires an interacting protein, protein kinase C and casein kinase 2 substrate in neurons 1 (PACSIN1). This protein has the ability to bind both N17 and the polyproline region, stabilizing the interaction between these two domains. We also developed an antibody-based FRET assay that can detect conformational changes within endogenous huntingtin in wild-type versus HD fibroblasts. Therefore, we hypothesize that wild-type length polyglutamine tracts within huntingtin can form a flexible domain that is essential for proper functional intramolecular proximity, conformations, and dynamics.
Targeting proximal tubule mitochondrial dysfunction attenuates the renal disease of methylmalonic acidemia
Authors: Manoli Irini , Sysol Justin R. , Li Lingli , Houillier Pascal , Garone Caterina , Wang Cindy , Zerfas Patricia M. , Cusmano-Ozog Kristina , Young Sarah , Trivedi Niraj S. , Cheng Jun , Sloan Jennifer L. , Chandler Randy J. , Abu-Asab Mones , Tsokos Maria , Elkahloun Abdel G. , Rosen Seymour , Enns Gregory M. , Berry Gerard T. , Hoffmann Victoria , DiMauro Salvatore , Schnermann Jurgen , Venditti Charles P.
Published: July 2013

Isolated methylmalonic acidemia (MMA), caused by deficiency of the mitochondrial enzyme methylmalonyl-CoA mutase (MUT), is often complicated by end stage renal disease that is resistant to conventional therapies, including liver transplantation. To establish a viable model of MMA renal disease,
Mut
was expressed in the liver of
Mut
−/−
mice as a stable transgene under the control of an albumin (INS-Alb-
Mut
) promoter.
Mut
−/−
;Tg

INS-Alb-
Mut

mice, although completely rescued from neonatal lethality that was displayed by
Mut
−/−
mice, manifested a decreased glomerular filtration rate (GFR), chronic tubulointerstitial nephritis and ultrastructural changes in the proximal tubule mitochondria associated with aberrant tubular function, as demonstrated by single-nephron GFR studies. Microarray analysis of
Mut
−/−
;Tg

INS-Alb-
Mut

kidneys identified numerous biomarkers, including lipocalin-2, which was then used to monitor the response of the GFR to antioxidant therapy in the mouse model. Renal biopsies and biomarker analysis from a large and diverse patient cohort (
ClinicalTrials.gov
identifier: NCT00078078) precisely replicated the findings in the animals, establishing
Mut
−/−
;Tg

INS-Alb-
Mut

mice as a unique model of MMA renal disease. Our studies suggest proximal tubular mitochondrial dysfunction is a key pathogenic mechanism of MMA-associated kidney disease, identify lipocalin-2 as a biomarker of increased oxidative stress in the renal tubule, and demonstrate that antioxidants can attenuate the renal disease of MMA.
Dynamic model constraints on oxygen-17 depletion in atmospheric O
2
after a snowball Earth
Authors: Cao Xiaobin , Bao Huiming
Published: July 2013

A large perturbation in atmospheric CO
2
and O
2
or bioproductivity will result in a drastic pulse of
17
O change in atmospheric O
2
, as seen in the Marinoan Oxygen-17 Depletion (MOSD) event in the immediate aftermath of a global deglaciation 635 Mya. The exact nature of the perturbation, however, is debated. Here we constructed a coupled, four-box, and quick-response biosphere–atmosphere model to examine both the steady state and dynamics of the MOSD event. Our model shows that the ultra-high CO
2
concentrations proposed by the “snowball’ Earth hypothesis produce a typical MOSD duration of less than 10
6
y and a magnitude of
17
O depletion reaching approximately −35‰. Both numbers are in remarkable agreement with geological constraints from South China and Svalbard. Moderate CO
2
and low O
2
concentration (e.g., 3,200 parts per million by volume and 0.01 bar, respectively) could produce distinct sulfate
17
O depletion only if postglacial marine bioproductivity was impossibly low. Our dynamic model also suggests that a snowball in which the ocean is isolated from the atmosphere by a continuous ice cover may be distinguished from one in which cracks in the ice permit ocean–atmosphere exchange only if partial pressure of atmospheric O
2
is larger than 0.02 bar during the snowball period and records of weathering-derived sulfate are available for the very first few tens of thousands of years after the onset of the meltdown. In any case, a snowball Earth is a precondition for the observed MOSD event.
Energetic cost of brain functional connectivity
Authors: Tomasi Dardo , Wang Gene-Jack , Volkow Nora D.
Published: July 2013

The brain's functional connectivity is complex, has high energetic cost, and requires efficient use of glucose, the brain's main energy source. It has been proposed that regions with a high degree of functional connectivity are energy efficient and can minimize consumption of glucose. However, the relationship between functional connectivity and energy consumption in the brain is poorly understood. To address this neglect, here we propose a simple model for the energy demands of brain functional connectivity, which we tested with positron emission tomography and MRI in 54 healthy volunteers at rest. Higher glucose metabolism was associated with proportionally larger MRI signal amplitudes, and a higher degree of connectivity was associated with nonlinear increases in metabolism, supporting our hypothesis for the energy efficiency of the connectivity hubs. Basal metabolism (in the absence of connectivity) accounted for 30% of brain glucose utilization, which suggests that the spontaneous brain activity accounts for 70% of the energy consumed by the brain. The energy efficiency of the connectivity hubs was higher for ventral precuneus, cerebellum, and subcortical hubs than for cortical hubs. The higher energy demands of brain communication that hinges upon higher connectivity could render brain hubs more vulnerable to deficits in energy delivery or utilization and help explain their sensitivity to neurodegenerative conditions, such as Alzheimer’s disease.