bluuebunny/crossref_metadata_2025 huggingface dataset:
The effects of prenatal exposure to a ‘junk food’ diet on offspring food preferences and fat deposition can be mitigated by improved nutrition during lactation
Authors: Gugusheff J. R. , Vithayathil M. , Ong Z. Y. , Muhlhausler B. S.
Published: August 2013

Exposure to a maternal junk food (JF) diet in utero and during the suckling period has been demonstrated to increase the preference for palatable food and increase the susceptibility to diet-induced obesity in adult offspring. We aimed to determine whether the effects of prenatal exposure to JF could be ameliorated by cross-fostering offspring onto dams consuming a standard rodent chow during the suckling period. We report here that when all offspring were given free access to the JF diet for 7 weeks from 10 weeks of age, male offspring of control (C) or JF dams that were cross-fostered at birth onto JF dams (C-JF, JF-JF), exhibited higher fat (C-C: 12.3 ± 0.34 g/kg/day; C-JF: 14.7 ± 1.04 g/kg/day; JF-C: 11.5 ± 0.41 g/kg/day; JF-JF: 14.0 ± 0.44 g/kg/day; P < 0.05) and overall energy intake (C-C: 930.1 ± 18.56 kJ/kg/day; C-JF: 1029.0 ± 82.9 kJ/kg/day; JF-C: 878.3 ± 19.5 kJ/kg/day; JF-JF: 1003.4 ± 25.97 kJ/kg/day; P < 0.05) than offspring exposed to the JF diet only before birth (JF-C) or not at all (C-C). Female offspring suckled by JF dams, despite no differences in food intake, had increased fat mass as percentage of body weight (C-C: 19.9 ± 1.33%; C-JF: 22.8 ± 1.57%; JF-C: 17.4 ± 1.03%; JF-JF: 22.0 ± 1.0%; P < 0.05) after 3 weeks on the JF diet. No difference in fat mass was observed in male offspring. These findings suggest that the effects of prenatal exposure to a JF diet on food preferences in females and susceptibility to diet-induced obesity in males can be prevented by improved nutrition during the suckling period.
Cultural Influences on Body Size Ideals
Authors: Swami Viren
Published: August 2013

Given that an important component of perceptual body dissatisfaction is the discrepancy between ideal and current body sizes, understanding how body size ideals are shaped and transmitted remains an important task for scholars. This review begins by examining cross-cultural patterns of body size ideals. Evidence is presented to indicate that the largest differences in body size ideals are no longer found between Western and non-Western cultures, but between sites differing in socioeconomic status. It is further argued that a thin ideal is now prevalent in most socioeconomically developed, urban sites. In explanation, it has been suggested that both Westernization and modernization bring cultural changes that promote a thin ideal. The present article reviews evidence in favor of both factors and concludes by looking at clinical implications for understanding corporeal experiences in a globalized world.
Turning the Analytic Gaze on “Us”
Authors: Blackwood Leda , Hopkins Nick , Reicher Steve
Published: August 2013

What leads to the alienation and political (dis)engagement of minority groups is a critical question for political psychologists. Recently, research has focused attention on one particular minority group – Muslims in the West – and on what promotes “anti-Western” attitudes and behavior. Typically, the research focus is on factors internal to the individuals or the minority communities concerned. However, we argue this overlooks the ways in which the perspective and practices of the majority group affect minority group members’ understandings of who they are and how they stand in relation to the majority. In this paper we examine the social-psychological processes through which authorities’ surveillance and intervention affects minority group members’ sense of themselves, their relationship to authorities and the wider community. In doing so, we discuss a number of hitherto neglected psychological processes that may contribute to alienation-namely, processes of misrecognition, disrespect, and humiliation. We draw on research conducted with British Muslims to illustrate our argument for widening our analytic focus to give a more dynamic account of alienation and (dis)engagement.
Messenger RNA is a functional component of a chromatin insulator complex
Authors: Matzat Leah H , Dale Ryan K , Lei Elissa P
Published: August 2013

Chromatin insulators are DNA protein complexes situated throughout the genome capable of demarcating independent transcriptional domains. Previous studies point to an important role for RNA in gypsy chromatin insulator function in Drosophila; however, the identity of these putative insulator‐associated RNAs is not currently known. Here we utilize RNA‐immunoprecipitation and high throughput sequencing (RIP‐seq) to isolate RNAs stably associated with gypsy insulator complexes. Strikingly, these RNAs correspond to specific sense‐strand, spliced and polyadenylated mRNAs, including two insulator protein transcripts. In order to assess the functional significance of these associated mRNAs independent of their coding function, we expressed untranslatable versions of these transcripts in developing flies and observed both alteration of insulator complex nuclear localization as well as improvement of enhancer‐blocking activity. Together, these data suggest a novel, noncoding mechanism by which certain mRNAs contribute to chromatin insulator function.
Bioactive baculovirus nanohybrids for stent based rapid vascular re-endothelialization
Authors: Paul Arghya , Elias Cynthia B. , Shum-Tim Dominique , Prakash Satya
Published: August 2013

Present study, for the first time, reports the development of a nanohybridized baculovirus based stent that can locally promote vascular re-endothelialization by efficient delivery of pro-angiogenic vascular endothelial growth factor (Vegf) genes. In vitro data demonstrated rapid expression of functionally active Vegf by the bioactive stent-transduced vascular cells. In vivo site-specific transgene expression was observed at the stented regions of balloon-denuded canine femoral artery, which eventually lead to significant endothelial recovery at the injured sites. A significant reduction in neointima formation (2.23 ± 0.56 mm2 vs 2.78 ± 0.49 mm2 and 3.11 ± 0.23 mm2, p < 0.05; n = 8) and percent stenosis was observed in treated stent group compared to negative control and bare metal stent groups. These findings collectively implicate the potential of this newly developed baculovirus based biotherapeutic stent to ameliorate damaged vascular biology and attenuate re-narrowing of stented artery by inhibiting neointima formation.
Guiding Parents From Diverse Cultural Backgrounds to Promote Language Skills in Preschoolers With Language Disorders: Two Challenges and Proposed Solutions for Them
Authors: van Kleeck Anne
Published: August 2013

In providing culturally sensitive services for the families of young children with language disorders, the SLP is often confronted with a set of challenges. The first relates to avoiding making assumptions about the communication practices of any particular family, and is called the “avoid stereotyping” challenge. The solution offered is to repurpose the routines-based interview that is becoming more widely used in early intervention services (e.g., Bernheimer & Weisner, 2007; McWilliam, 2012; McWilliam, Casey, & Sims, 2009) in order to help the SLP determine (in a nonjudgmental fashion) the frequency and specific nature of interactions that occur in the home. When families do not display interaction patterns that evidence suggests foster language development and school success, how does the SLP both value the family's preferred practices and offer suggestions for interaction that may contradict them? The solution offered for this challenge, referred to as the “avoiding mixed messages” challenge, is to talk with parents about how such interactions will better prepare their child for the language demands of school. This is referred to as the “blaming the schools” solution.
Total throughput maximisation in a cognitive radio network
Authors: Khalili Shahrooz , Jamshidi Azizollah , Derakhtian Mostafa
Published: August 2013

In cognitive radio (CR) networks, the channel sensing performance has significant impact on the throughput of the system. In this study, the authors formulate the spectrum sensing to maximise the total throughput of the system under some constraints on the interference to the primary users (Pus). The total throughput defined in this study accounts not only for the throughput achieved by the CR user but also by the PU over each subband. In the numerical results, the authors compare their proposed idea with the previous work which finds the threshold of the detector to maximise CR throughput.
Capacity for the doubly dirty multiple access channel with partial side information at the transmitters
Authors: Bahmani Elham , Abed Hodtani Ghosheh
Published: August 2013

In this study, the authors establish achievable rate and capacity regions for three kinds of Gaussian multiple access channels (MACs) with side information (SI) partially (estimated or sensed version) and non‐causally known at the transmitters. Actually, the authors show that the lattice strategy is optimal for Gaussian MACs with partial SI, the same as it is for Gaussian MACs with full SI studied by Philosof–Zamir. The rate and capacity regions, while showing that partiality in SI reduces the achievable rates, subsumes directly the Philosof–Zamir rate regions and also the Gueguen–Sayrac work and the Costa theorem indirectly as special cases.
Performance analysis of adaptive M‐ary quadrature amplitude modulation for amplify‐and‐forward opportunistic relaying under outdated channel state information
Authors: Torabi Mohammad , Frigon Jean‐François , Haccoun David
Published: August 2013

The impact of outdated channel state information (CSI) on the performance of variable‐rate adaptive M‐ary quadrature amplitude modulation in amplify‐and‐forward (AF) opportunistic relaying systems over time‐variant Rayleigh fading channels is analysed. Two rate‐adaptive modulation techniques are considered. In the first scheme, the relay and the transmission rate are selected according to the CSI at the receiver side. In the second scheme, whereas selection of the relay is based on the receiver's CSI, the transmission rate is selected based on the predicted CSI at the transmitter after the feedback delay. The impact of imperfect CSI prediction on the system performance is also evaluated. For each scheme, analytical expressions are derived for the average spectral efficiency, outage probability and the average bit‐error rate under outdated CSI. Using numerical evaluations the performances of the considered rate‐adaptive modulation schemes are analysed to illustrate the impact of outdated CSI on AF opportunistic relaying systems.
Physical layer network coding with channel and delay estimation
Authors: Li Yixin , Zheng Fu‐Chun , Fitch Michael
Published: August 2013

Decode‐and‐forward physical layer network coding (PLNC) is one of the promising high‐performance techniques for wireless relay networks. This study presents a channel and delay estimation algorithm along with a detection scheme for time‐domain two‐way relay network in Rayleigh block fading channels. Preambles are attached for frame‐based synchronisation and channel estimation. Moreover, to achieve low‐complexity estimation, the preambles are designed in Alamouti code structure. The Cramer–Rao bound (CRB) of the channel estimation is given, and simulations show that the mean‐square error of channel estimation of the proposed scheme could reach the CRB. Compared with the traditional approach, the newly proposed combined scheme can achieve almost the same performance, but with significant improvement in computational complexity. At last, bit‐error‐rate performances analysis is given. Simulation validates the authors’ analysis, and shows the upper bound and lower bound are tight.
Performance analysis of protograph low‐density parity‐check codes for Nakagami‐m fading relay channels
Authors: Fang Yi , Wong Kai‐Kit , Wang Lin , Tong Kin‐Fai
Published: August 2013

In this study, the authors investigate the error performance of the protograph (low‐density parity check) codes over Nakagami‐m fading relay channels. The authors first calculate the decoding thresholds of the protograph codes over such channels with different fading depths (i.e. different values of m) by exploiting the modified protograph extrinsic information transfer (PEXIT) algorithm. Furthermore, based on the PEXIT analysis and using Gaussian approximation, the authors derive the bit‐error‐rate (BER) expressions for the error‐free (EF) relaying protocol and decode‐and‐forward (DF) relaying protocol. The authors finally compare the threshold with the theoretical BER and the simulated BER results of the protograph codes. It reveals that the performance of DF protocol is approximately the same as that of EF protocol. Moreover, the theoretical BER expressions, which are shown to be reasonably consistent with the decoding thresholds and the simulated BERs, are able to evaluate the system performance and predict the decoding threshold with lower complexity as compared with the modified PEXIT algorithm. As a result, this work can facilitate the design of the protograph codes for the wireless communication systems.
Enhanced and directional transmission through a slit surrounded with grooves in a conducting plane
Authors: Na Dong Yeop , Kim Ji Hyung , Park Yong Bae , Jung Kyung‐Young
Published: August 2013

Enhanced and directional transmission through a slit surrounded with grooves in a conducting plane is investigated. A boundary‐value problem of electromagnetic wave scattering from a slit surrounded with a finite number of rectangular grooves on both surfaces in a conducting plane is rigorously solved based on the eigenfunction expansion, Fourier transform and mode matching method. The radiated power density and the transmission coefficient are represented in a series. Computation is performed to illustrate the transmission behaviours in terms of the groove geometry.
Inkjet‐printed antennas, sensors and circuits on paper substrate
Authors: Kim Sangkil , Cook Benjamin , Le Taoran , Cooper James , Lee Hoseon , Lakafosis Vasileios , Vyas Rushi , Moro Riccardo , Bozzi Maurizio , Georgiadis Apostolos , Collado Ana , Tentzeris Manos M.
Published: August 2013

Inkjet‐printing is a very promising technology for the development of microwave circuits and components. Inkjet‐printing technology of conductive silver nanoparticles on an organic flexible paper substrate is introduced in this study. The paper substrate is characterised using the T‐resonator method. A variety of microwave passive and active devices, as well as complete circuits inkjet‐printed on paper substrates are introduced. This work includes inkjet‐printed artificial magnetic conductor structures, a substrate integrated waveguide, solar‐powered beacon oscillator for wireless power transfer and localisation, energy harvesting circuits and nanocarbon‐based gas‐sensing materials such as carbon nanotubes and graphene. This study presents an overview of recent advances of inkjet‐printed electronics on paper substrate.
Uniplanar polarisation diversity antenna for ultra‐wideband systems
Authors: Chacko Bybi P. , Augustin Gijo , Denidni Tayeb A.
Published: August 2013

A new compact, uniplanar, polarisation‐diversity, monopole‐like slot antenna for ultra‐wideband (UWB) systems is presented. The proposed design effectively integrates orthogonally fed slot antennas, utilising the uniplanar nature of coplanar waveguide without degrading the time‐domain characteristics and diversity performance. To achieve high isolation between the ports, a strip is integrated diagonally in the ground plane. Furthermore, by loading arc shaped slot resonators on the feeding structures, the proposed antenna successfully rejects the undesired subband, assigned for IEEE 802.11a and HIPERLAN/2. The measured results demonstrate that the antenna provides a 2:1 voltage standing wave ratio (VSWR) band from 2.76 to 10.75 GHz whereas showing rejection in the frequency band 4.75–6.12 GHz, along with an inter‐port isolation better than 15 dB. The proposed radiator displays a nearly omnidirectional radiation pattern, along with a moderate gain and efficiency. The envelope correlation coefficient discloses a good diversity performance across the UWB spectrum. Furthermore, the time‐domain analysis shows minimum dispersion to the radiated pulse. In addition, the experimental analysis indicates that the proposed design is less disposed to the housing effects when mounted in metallic casing. All these features make the proposed antenna a viable candidate for UWB dual‐polarised multiple‐input–multiple‐output applications.
Planar wideband inphase power divider/combiner using modified Gysel structure
Authors: Abbosh Amin , Henin Bassem
Published: August 2013

The design of a wideband inphase power divider/combiner is presented. It uses a modified Gysel structure for an increased band and a reduced number of isolation resistors to only one. The power divider has a simple structure that does not use any slots in the ground plane, and is thus fully compatible with microstrip circuits. Moreover, the device uses one external isolation resistor, and thus it is suitable for high‐power microwave applications because of the easy connection of the isolation resistor to a suitable heat sink. A theoretical analysis is presented to find the values of the design parameters for wideband performance. The simulated and experimental results of the designed divider show 69% fractional bandwidth assuming 15 dB of isolation as a reference.
Multi‐band and multi‐polarised reconfigurable antenna for next generation mobile communication base‐station applications
Authors: Choi Sung‐Woong , Jung Young‐Bae , Park Seong‐Ook
Published: August 2013

A novel multi‐band reconfigurable antenna for a mobile base‐station is proposed. This antenna can be operated in three bands using three radiators, but the radiators are physically combined into one body in consideration of size reduction and optimal performance. Radiator 1 is a square patch structure and is operated in 0.824–0.894 GHz for cellular service. Radiator 2 provides multiple mobile services in 1.75–2.48 GHz for personal communication service (PCS), wideband code division multiple access (WCDMA), world interoperability for microwave access (WiMAX) and WiFi, and thus has a wideband characteristic using a printed dipole structure. Finally, radiator 3 has a stacked structure composed of a radiating and a parasitic patch in 3.3–3.6 GHz for WiMAX2. Radiator 1 has a cylindrical cavity in the centre of the patch, and is designed not to degrade electrical performance, and radiator 3 is embedded in the cavity of radiator 1. Radiator 2 is composed of four printed dipoles and is vertically stacked on radiator 1 around radiator 3 with a rectangular formation. All radiators can provide dual‐polarisation using multi‐ports controlled by a switching circuit with a control program. In the switching circuit, there are two MEMS switches for band selection. Using the proposed structure, the authors realise a novel multi‐functional reconfigurable antenna using three individual radiators.
Bandwidth limitations of ultra high frequency–radio frequency identification tags
Authors: Zamora Gerard , Paredes Ferran , Herraiz‐Martínez Francisco Javier , Martín Ferran , Bonache Jordi
Published: August 2013

Fundamental bandwidth limitations on the design of ultra high frequency (UHF) radio frequency identiﬁcation (RFID) tags are investigated. This study was conducted by considering the optimum equivalent‐circuit network necessary for bandwidth broadening in single resonant UHF–RFID tags with conjugate matching. This equivalent‐circuit network is simply a parallel combination of an inductor and a resistor cascaded to the UHF–RFID chip. Bandwidth optimisation of the resulting network is validated by means of the Bode criterion. According to this analysis, a broadband UHF–RFID tag prototype able to operate worldwide is designed and fabricated. In order to reduce tag size and cost, the external matching network is omitted in the reported implementation. The measured read ranges are above 5 m within the whole UHF–RFID frequency band (840–960 MHz), with a peak value of 9 m at 870 MHz.
Design of synthetic biological logic circuits based on evolutionary algorithm
Authors: Chuang Chia‐Hua , Lin Chun‐Liang , Chang Yen‐Chang , Jennawasin Tanagorn , Chen Po‐Kuei
Published: August 2013

The construction of an artificial biological logic circuit using systematic strategy is recognised as one of the most important topics for the development of synthetic biology. In this study, a real‐structured genetic algorithm (RSGA), which combines general advantages of the traditional real genetic algorithm with those of the structured genetic algorithm, is proposed to deal with the biological logic circuit design problem. A general model with the cis ‐regulatory input function and appropriate promoter activity functions is proposed to synthesise a wide variety of fundamental logic gates such as NOT, Buffer, AND, OR, NAND, NOR and XOR. The results obtained can be extended to synthesise advanced combinational and sequential logic circuits by topologically distinct connections. The resulting optimal design of these logic gates and circuits are established via the RSGA. The in silico computer‐based modelling technology has been verified showing its great advantages in the purpose.
Analysis of a near-metric TSP approximation algorithm
Authors: Krug Sacha
Published: August 2013

The traveling salesman problem (TSP) is one of the most fundamental optimization
problems. We consider the β-metric traveling salesman problem
(Δβ-TSP), i.e., the TSP
restricted to graphs satisfying the β-triangle inequality
c({v,w}) ≤ β(c({v,u}) + c({u,w})),
for some cost function c and any three vertices u,v,w.
The well-known path matching Christofides algorithm (PMCA) guarantees an approximation
ratio of 3β2/2 and is the best known algorithm for the
Δβ-TSP, for 1 ≤ β ≤ 2. We
provide a complete analysis of the algorithm. First, we correct an error in the original
implementation that may produce an invalid solution. Using a worst-case example, we then
show that the algorithm cannot guarantee a better approximation ratio. The example can
also be used for the PMCA variants for the Hamiltonian path problem with zero and one
prespecified endpoints. For two prespecified endpoints, we cannot reuse the example, but
we construct another worst-case example to show the optimality of the analysis also in
this case.
Metamaterial anisotropic flux concentrators and magnetic arrays
Authors: Bjørk R. , Smith A. , Bahl C. R. H.
Published: August 2013

A metamaterial magnetic flux concentrator is investigated in detail in combination with a Halbach cylinder of infinite length. A general analytical solution to the field is determined and the magnetic figure of merit is determined for a Halbach cylinder with a flux concentrator. It is shown that an ideal flux concentrator will not change the figure of merit of a given magnet design, while the non-ideal will always lower it. The geometric parameters producing maximum figure of merit, i.e., the most efficient devices, are determined. The force and torque between two concentric Halbach cylinders with flux concentrators is determined and the maximum torque is found. Finally, the effect of non-ideal flux concentrators and the practical use of flux concentrators, as well as demagnetization issues, is discussed.
Interacting hard rods on a lattice: Distribution of microstates and density functionals
Authors: Bakhti Benaoumeur , Müller Gerhard , Maass Philipp
Published: August 2013

We derive exact density functionals for systems of hard rods with first-neighbor interactions of arbitrary shape but limited range on a one-dimensional lattice. The size of all rods is the same integer unit of the lattice constant. The derivation, constructed from conditional probabilities in a Markov chain approach, yields the exact joint probability distribution for the positions of the rods as a functional of their density profile. For contact interaction (“sticky core model”) between rods, we give a lattice fundamental measure form of the density functional and present explicit results for contact correlators, entropy, free energy, and chemical potential. Our treatment includes inhomogeneous couplings and external potentials.
Pump and probe waves in dynamic acousto-elasticity: Comprehensive description and comparison with nonlinear elastic theories
Authors: Rivière J. , Renaud G. , Guyer R. A. , Johnson P. A.
Published: August 2013

Standard nonlinear ultrasonic methods such as wave frequency mixing or resonance based measurements allow one to extract average, bulk variations of modulus and attenuation versus strain level. In contrast, dynamic acousto-elasticity (DAE) provides the elastic behavior over the entire dynamic cycle including hysteresis and memory effects, detailing the full nonlinear behavior under tension and compression. In this work, we address experimental difficulties and apply new processing methods, illustrating them with a Berea sandstone sample. A projection procedure is used to analyze the complex nonlinear signatures and extract the harmonic content. Amplitude dependences of the harmonic content are compared with existing models. We show that a combination of classical and hysteretic nonlinear models capture most of the observed phenomena. Some differences between existing models and experimental data are highlighted, however. A progressive decrease of the power-law amplitude dependence is found for harmonics larger than the second and for strains larger than 10−6. This observation is related to the phenomenon of acoustic conditioning that brings the material to a metastable state for each new excitation amplitude. Analysis of the steady-state regime provides additional information regarding acoustic conditioning, i.e., a progressive decrease of the amplitude of odd harmonics during excitation time with a log(t)-dependence. This observation confirms that the harmonic content is affected by the conditioning. Experimental challenges addressed include the fact that the compressional mode used for DAE can be affected by bending/torsion modes: their influence is evaluated, and guidances are given to minimize effects.
Experimental observation and analysis of the 3ν1(Σg) stretching vibrational state of acetylene using continuous-wave infrared stimulated emission
Authors: Siltanen Mikael , Metsälä Markus , Vainio Markku , Halonen Lauri
Published: August 2013

We present a sensitive experimental method for molecular spectroscopy that can be used to determine ro-vibrational states using mid-infrared stimulated emission. Our infrared stimulated emission probing (IRSEP) experiment is based on using a narrow-line, continuous-wave Ti:sapphire laser beam (pump) to excite the molecules to an upper vibrational state and a continuous-wave, mid-infrared beam from an optical parametric oscillator (probe) to detect the stimulated emission by the excited molecules. Spectroscopic data are gathered by tuning the wavelengths of the beams. The molecules are probed before their velocity distribution is disturbed by collisions, which leads to a sub-Doppler resolution. The full width at half maximum of the emission peaks is below 10 MHz. The stimulated emission lines are measured with an accuracy of at least 0.005 cm−1. We use the IRSEP experiment to observe and analyze the symmetric ro-vibrational state [21+] (3ν1(Σg)) of acetylene (C2H2). This state is not accessible via one photon transitions from the ground vibrational state. We use the least-squares method to determine that the band center is at 9991.9725 (12) cm−1 and the rotational parameters are B = 1.156145 (22) and D = 1.608 (87) × 10−6 cm−1, where the uncertainties in parentheses are one-standard errors in the least significant digit.
Computational studies of catalyst-free single walled carbon nanotube growth
Authors: Haghighatpanah S. , Mohsenzadeh A. , Amara H. , Bichara C. , Bolton K.
Published: August 2013

Semiempirical tight binding (TB) and density functional theory (DFT) methods have been used to study the mechanism of single walled carbon nanotube (SWNT) growth. The results are compared with similar calculations on graphene. Both TB and DFT geometry optimized structures of relevance to SWNT growth show that the minimum energy growth mechanism is via the formation of hexagons at the SWNT end. This is similar to the result for graphene where growth occurs via the formation of hexagons at the edge of the graphene flake. However, due to the SWNT curvature, defects such as pentagons are more stable in SWNTs than in graphene. Monte Carlo simulations based on the TB energies show that SWNTs close under conditions that are proper for growth of large defect-free graphene flakes, and that a particle such as a Ni cluster is required to maintain an open SWNT end under these conditions. The calculations also show that the proper combination of growth parameters such as temperature and chemical potential are required to prevent detachment of the SWNTs from the Ni cluster or encapsulation of the cluster by the feedstock carbon atoms.
Windowless ultrasound photoacoustic cell for in vivo mid-IR spectroscopy of human epidermis: Low interference by changes of air pressure, temperature, and humidity caused by skin contact opens the possibility for a non-invasive monitoring of glucose in the interstitial fluid
Authors: Pleitez Miguel A. , Lieblein Tobias , Bauer Alexander , Hertzberg Otto , von Lilienfeld-Toal Hermann , Mäntele Werner
Published: August 2013

The application of a novel open, windowless cell for the photoacoustic infrared spectroscopy of human skin is described. This windowless cavity is tuned for optimum performance in the ultrasound range between 50 and 60 kHz. In combination with an external cavity tunable quantum cascade laser emitting in the range from ∼1000 cm−1 to 1245 cm−1, this approach leads to high signal-to-noise-ratio (SNR) for mid-infrared spectra of human skin. This opens the possibility to measure in situ the absorption spectrum of human epidermis in the mid-infrared region at high SNR in a few (∼5) seconds. Rapid measurement of skin spectra greatly reduces artifacts arising from movements. As compared to closed resonance cells, the windowless cell exhibits the advantage that the influence of air pressure variations, temperature changes, and air humidity buildup that are caused by the contact of the cell to the skin surface can be minimized. We demonstrate here that this approach can be used for continuous and non-invasive monitoring of the glucose level in human epidermis, and thus may form the basis for a non-invasive monitoring of the glucose level for diabetes patients.
Magnetic dipole discharges. III. Instabilities
Authors: Stenzel R. L. , Urrutia J. M. , Ionita C. , Schrittwieser R.
Published: August 2013

Instabilities in a cross-field discharge around a permanent magnet have been investigated. The permanent magnet serves as a cold cathode and the chamber wall as an anode. The magnet is biased strongly negative and emits secondary electrons due to impact of energetic ions. The electrons outside the sheath are confined by the strong dipolar magnetic field and by the ion-rich sheath surrounding the magnet. The electron energy peaks in the equatorial plane where most ionization occurs and the ions are trapped in a negative potential well. The discharge mechanism is the same as that of cylindrical and planar magnetrons, but here extended to a 3-D cathode geometry using a single dipole magnet. While the basic properties of the discharge are presented in a companion paper, the present focus is on various observed instabilities. The first is an ion sheath instability which oscillates the plasma potential outside the sheath below the ion plasma frequency. It arises in ion-rich sheaths with low electron supply, which is the case for low secondary emission yields. Sheath oscillations modulate the discharge current creating oscillating magnetic fields. The second instability is current-driven ion sound turbulence due to counter-streaming electrons and ions. The fluctuations have a broad spectrum and short correlation lengths in all directions. The third type of fluctuations is spiky potential and current oscillations in high density discharges. These appear to be due to unstable emission properties of the magnetron cathode.
Are trinuclear superhalogens promising candidates for building blocks of novel magnetic materials? A theoretical prospect from combined broken-symmetry density functional theory and ab initio study
Authors: Yu Yang , Li Chen , Yin Bing , Li Jian-Li , Huang Yuan-He , Wen Zhen-Yi , Jiang Zhen-Yi
Published: August 2013

The structures, relative stabilities, vertical electron detachment energies, and magnetic properties of a series of trinuclear clusters are explored via combined broken-symmetry density functional theory and ab initio study. Several exchange-correlation functionals are utilized to investigate the effects of different halogen elements and central atoms on the properties of the clusters. These clusters are shown to possess stronger superhalogen properties than previously reported dinuclear superhalogens. The calculated exchange coupling constants indicate the antiferromagnetic coupling between the transition metal ions. Spin density analysis demonstrates the importance of spin delocalization in determining the strengths of various couplings. Spin frustration is shown to occur in some of the trinuclear superhalogens. The coexistence of strong superhalogen properties and spin frustration implies the possibility of trinuclear superhalogens working as the building block of new materials of novel magnetic properties.
Miniature Hall sensor integrated on a magnetic thin film for detecting domain wall motion
Authors: Kubota M. , Tokunaga Y. , Kanazawa N. , Kagawa F. , Tokura Y. , Kawasaki M.
Published: August 2013

We have fabricated a cross-bar Hall sensor made of 50-nm-wide and 100-nm-thick bismuth wires patterned by an electron-beam lithography and lift-off. The Hall coefficient at 300 K is as large as −0.44 cm3/C, yielding in a high product sensitivity of about 5 V/(A T). The series resistance was reduced as low as 1.7 kΩ with a short bar configuration, resulting in a high signal-to-noise ratio of 38.5 dB. These characteristics are far better than those reported with similar dimensions. The Hall element was successfully demonstrated for detecting the domain wall motion in an iron garnet film employed as the substrate.
Minimal transition thresholds in plane Couette flow
Authors: Duguet Yohann , Monokrousos Antonios , Brandt Luca , Henningson Dan S.
Published: August 2013

Subcritical transition to turbulence requires finite-amplitude perturbations. Using a nonlinear optimisation technique in a periodic computational domain, we identify the perturbations of plane Couette flow transitioning with least initial kinetic energy for Re ⩽ 3000. We suggest a new scaling law Ec = O(Re−2.7) for the energy threshold vs. the Reynolds number, in quantitative agreement with experimental estimates for pipe flow. The route to turbulence associated with such spatially localised perturbations is analysed in detail for Re = 1500. Several known mechanisms are found to occur one after the other: Orr mechanism, oblique wave interaction, lift-up, streak bending, streak breakdown, and spanwise spreading. The phenomenon of streak breakdown is analysed in terms of leading finite-time Lyapunov exponents of the associated edge trajectory.
Electronic- and band-structure evolution in low-doped (Ga,Mn)As
Authors: Yastrubchak O. , Sadowski J. , Krzyżanowska H. , Gluba L. , Żuk J. , Domagala J. Z. , Andrearczyk T. , Wosinski T.
Published: August 2013

Modulation photoreflectance spectroscopy and Raman spectroscopy have been applied to study the electronic- and band-structure evolution in (Ga,Mn)As epitaxial layers with increasing Mn doping in the range of low Mn content, up to 1.2%. Structural and magnetic properties of the layers were characterized with high-resolution X-ray diffractometry and SQUID magnetometery, respectively. The revealed results of decrease in the band-gap-transition energy with increasing Mn content in very low-doped (Ga,Mn)As layers with n-type conductivity are interpreted as a result of merging the Mn-related impurity band with the host GaAs valence band. On the other hand, an increase in the band-gap-transition energy with increasing Mn content in (Ga,Mn)As layers with higher Mn content and p-type conductivity indicates the Moss-Burstein shift of the absorption edge due to the Fermi level location within the valence band, determined by the free-hole concentration. The experimental results are consistent with the valence-band origin of mobile holes mediating ferromagnetic ordering in the (Ga,Mn)As diluted ferromagnetic semiconductor.
Theoretical prediction of high pressure phase transition in ScC and YC: Ab initio calculations
Authors: Sahoo B. D. , Joshi K. D. , Gupta Satish C.
Published: August 2013

The structural stability of ScC and YC has been analyzed under hydrostatic compression employing the first-principles calculations using the plane-wave pseudopotential method. The comparison of theoretically calculated enthalpies of rocksalt type (B1), primitive orthorhombic (Pmmn), and CsCl type (B2) structures as a function of pressure suggests that the B1 structure transforms to Pmmn phase instead of transforming to B2 phase that predicted by Soni et al. [J. Phys. Chem. Solids 72, 810 (2011)]. The pressure for B1 to Pmmn transition predicted for ScC and YC are ∼80 GPa and ∼30 GPa, respectively. To further substantiate the outcomes of our static lattice calculations, we have performed lattice dynamic calculations also. Our lattice dynamic calculations correctly demonstrate that the B1 phase is dynamically stable structure at ambient condition. Further, for both the carbides, we find that the Pmmn structure becomes dynamically stable around the transition pressure whereas the B2 structure remains unstable, supporting the B1 to Pmmn phase transition predicted by our static lattice calculations.
Interface optical phonon modes in wurtzite quantum heterostructures
Authors: Zhang Nanzhu , Liao Sicheng , Dutta Mitra , Stroscio Michael A.
Published: August 2013

Simple analytical expressions are derived, herein, for the interface phonon modes of complex SiC- and GaN-based substrates. These analytical results are essential for studies of remote polar-optical phonon phenomena in a variety of structures including heterostructures, in two-dimensional (2D) structures such and graphene, BN, and MoS2 on polar substrates, as well as in efforts to control the bandgaps of such 2D structures through interactions with polar substrates.
Note: Simultaneous measurements of magnetization and electrical transport signal by a reconstructed superconducting quantum interference device magnetometer
Authors: Wang H. L. , Yu X. Z. , Wang S. L. , Chen L. , Zhao J. H.
Published: August 2013

We have developed a sample rod which makes the conventional superconducting quantum interference device magnetometer capable of performing magnetization and electrical transport measurements simultaneously. The sample holder attached to the end of a 140 cm long sample rod is a nonmagnetic drinking straw or a 1.5 mm wide silicon strip with small magnetic background signal. Ferromagnetic semiconductor (Ga,Mn)As films are used to test the new sample rod, and the results are in good agreement with previous report.
Enhancement of thermoelectric performance in slightly charge-compensated CeyCo4Sb12 skutterudites
Authors: Qiu Pengfei , Shi Xun , Qiu Yuting , Huang Xiangyang , Wan Shun , Zhang Wenqing , Chen Lidong , Yang Jihui
Published: August 2013

Minute amounts of Fe/Mn are selected to be doped into CeyCo4Sb12 filled skutterudites to slightly compensate for electrons donated by the fillers. As a direct result, the Ce filling fractions are enhanced from 0.11 to 0.16. The carrier concentrations are improved by a factor of more than two times to approach the optimal values, leading to greatly improved power factors. Meanwhile, the lattice thermal conductivity is expectedly suppressed by the increased Ce fillers in the voids of skutterudites. Consequently, a maximum ZT of 1.3 at 850 K is obtained, which is comparable to that in the best single-filled skutterudites.
Anti-plane electro-mechanical behavior of piezoelectric composites with a nano-fiber considering couple stress at the interfaces
Authors: Fang Xue-Qian , Liu Xiang-Lin , Liu Jin-Xi , Nie Guo-Quan
Published: August 2013

Many nanostructures are assumed to be characterized by couple stress effects. Based on the couple stress theory and surface/interface theory, the anti-plane electro-mechanical behavior of piezoelectric composites with a nano-fiber is studied, and the effect of stress and electric displacement at the interface on the size-dependent behavior is examined. By introducing a decoupling function, the governing equations in piezoelectric materials are simplified into two classical governing equations. The displacement and electric potential are expressed by Bessel functions. By satisfying the boundary conditions around the nano-fiber with surface/interface effect, the expanded coefficients are obtained. Excellent agreement with the previous results validates this model. It can be concluded that the interface around the nano-fiber shows greater effect on the stress than that on the electrical fields, and the interface effect increases greatly due to the existence of couple stress. The effect of material properties of nano-fiber on the stress and electric field under different coupling stresses is also examined.
InP quantum dot lasers with temperature insensitive operating wavelength
Authors: Shutts S. , Smowton P. M. , Krysa A. B.
Published: August 2013

We quantify the mechanisms that govern the lasing wavelength in edge-emitting InP/AlGaInP quantum dot (QD) lasers, by characterising the constituent factors controlling the temperature dependence of the gain peak wavelength. We show that a regime exists where the temperature coefficient of the bandgap can be compensated by the increasing wavelength-shift associated with state-filling in the QD ensemble, necessary to recover the gain peak magnitude. We demonstrate cleaved-facet edge-emitting lasers with a wavelength temperature dependence of 0.03 nm/K, similar to the temperature dependence of a Bragg stack fabricated in this material and approximately a sixth of the dependence of the bandgap.
Analysis of electromagnetic modes excited in overmoded structure terahertz source
Authors: Li Xiaoze , Wang Jianguo , Xiao Renzhen , Wang Guangqiang , Zhang Lijun , Zhang Yuchuan , Ye Hu
Published: August 2013

A method on electromagnetic mode analysis in overmoded structure terahertz source is studied in this paper. This mode analysis method is based on Fourier-Bessel series and the particle-in-cell simulation. The result of mode analysis shows that there are TM02 and TM03 modes present in the waveguide motivated by mode change in the discontinuity. The mode content keeps stable when the device starts to work. The magnetic field and the voltage of beam do not change the mode content to some extent. The parameters of diode affect the mode content significantly.
Phase-mixing of electrostatic modes in a cold magnetized electron-positron plasma
Authors: Maity Chandan , Chakrabarti Nikhil , Sengupta Sudip
Published: August 2013

In a fluid description, we study space-time evolution of electrostatic oscillations in a cold magnetized electron-positron plasma. Nonlinear results up to third order, obtained by employing a simple perturbation technique, indicate phase-mixing and thus breaking of excited oscillations, and provide an expression for the phase-mixing time. It is shown that an increase in the strength of ambient magnetic field results in an increase in the phase-mixing time. The results of our investigation will be of relevance to astrophysical environments as well as laboratory experiments.
Coherent control of terahertz meta-materials
Authors: Enderli Florian , Feurer Thomas
Published: August 2013

We present coherent control of a THz meta-material. Specifically, we show in detail the time and frequency dependent response of a single and a double split ring resonator upon excitation with a shaped THz field. Through far- and near-field measurements, we confirm the coherence transfer from the tailored THz field to the system and back to the radiated field and we demonstrate selective excitation of a designated system resonance with a suitably shaped THz pulse.
Low voltage resistive switching devices based on chemically produced silicon oxide
Authors: Li Can , Jiang Hao , Xia Qiangfei
Published: August 2013

We developed nonvolatile metal/SiOx/Si memristive devices based on ultrathin (∼1 nm) silicon oxide that was produced in a Piranha solution. The devices exhibited repeatable resistive switching behavior with low programming voltages (as low as 0.5 V) and high ON/OFF conductance ratio. Devices with active metals as top electrodes were bipolar switches, while those with inert metal electrodes were unipolar. We also studied the switching mechanisms for both types of devices based on the filament formation and rupture, and proposed conduction models for Pt/SiOx/Si devices.
Multi-level resistive switching observations in asymmetric Pt/Ta2O5−x/TiOxNy/TiN/Ta2O5−x/Pt multilayer configurations
Authors: Rahm Lee Ah , Cheol Bae Yoon , Ho Baek Gwang , Sik Im Hyun , Pyo Hong Jin
Published: August 2013

We examine multilevel (ML) resistance switching properties in a Pt/Ta2O5−x/TiOxNy/TiN/Ta2O5−x/Pt matrix, in which two bipolar resistive switching elements Pt/Ta2O5−x/TiOxNy and TiN/Ta2O5−x/Pt are anti-serially and electrically connected. The ML features for the three assigned, distinguishable resistance states are clearly identified by using an I–V device operation scheme, indicating that the middle TiN and TiOxNy electrodes are crucial for adjusting ML resistance states. Experimental observations suggest that the ML switching events rely on electrically induced oxygen ion drifts at interfaces between the top/bottom Ta2O5−x and middle TiN/TiOxNy layers.