bluuebunny/crossref_metadata_2025 huggingface dataset:
Intravenous infusion of nerve growth factor‐secreting monocytes supports the survival of cholinergic neurons in the nucleus basalis of meynert in hypercholesterolemia brown‐norway rats
Authors: Hohsfield Lindsay A. , Ehrlich Daniela , Humpel Christian
Published: December 2013

The recruitment of monocytes into the brain has been implicated in Alzheimer's disease and recent studies have indicated that monocytes can reduce amyloid plaque burden. Our previous investigations have shown that hypercholesterolemic rats develop cognitive, cholinergic, and blood–brain barrier dysfunction, but do not develop amyloid plaques. This study was designed to evaluate the effects of repeated intravenous (i.v.) infusion (via the dorsal penile vein) of primary monocytes on cognition, the cholinergic system, and cortical cytokine levels in hypercholesterolemia Brown‐Norway rats. In addition, we also transduced the monocytes with nerve growth factor (NGF) to evaluate whether these cells could be used to deliver a neuroprotective agent to the brain. Our results indicate that repeated i.v. infused monocytes migrate into the brains of hypercholesterolemic rats; however, this migration does not translate into marked effects on learning. Animals receiving NGF‐loaded monocytes demonstrate slightly improved learning and significantly elevated cholinergic neuron staining compared to treatment with monocytes alone. Furthermore, our data indicate that repeated infusion of monocytes does not lead to elevated cytokine secretion, indicating that no inflammatory response is induced. This study provides an experimental attempt to evaluate the effects of blood‐derived primary monocytes in hypercholesterolemia rats. © 2013 Wiley Periodicals, Inc.
Effects of Molecular Architecture on the Stereocomplex Crystallization in Poly(lactic acid) Blends
Authors: Rathi Sahas R. , Ng David , Coughlin E. Bryan , Hsu Shaw Ling , Golub Charles S. , Ling Gerald H. , Tzivanis Michael J.
Published: December 2013

The crystallization behavior of two chemically identical but physically different co‐crystallizing poly(l‐lactic acid) (PLLA)‐based blends is studied. The first set studied involves an all‐l unit polymer (PLLA) co‐crystallizing with a PDLA–miscible soft polyether–PDLA triblock copoly­mer, where d refers to the d isomer. The second set studied involves homopolymer blends of PLLA/miscible soft polyether/PDLA with compositions identical to the first set. Crystallization is performed under isothermal and non‐isothermal crystallization conditions and the crystallization kinetics, crystal perfection, and the blend morphology are investigated. It is clear that the stereocomplex crystallization is significantly slower in the triblock copolymer blends in comparison with the homopolymer blends. Furthermore, based on diffraction, spectroscopic, and thermal data, it is found that the stereocomplex crystals formed in the homopolymer blends achieve higher order and perfection, with a melting temperature 15–20 °C higher than those formed in the triblock blends.

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Bicomplex holomorphic functional calculus
Authors: Colombo Fabrizio , Sabadini Irene , Struppa Daniele C.
Published: December 2013

In this paper we introduce and study a functional calculus for bicomplex linear bounded operators. The study is based on the decomposition of bicomplex numbers and of linear operators using the two nonreal idempotents. We show that, due to the presence of zero divisors in the bicomplex numbers, the spectrum of a bounded operator is unbounded. We therefore introduce a different spectrum (called reduced spectrum) which is bounded and turns out to be the right tool to construct the bicomplex holomorphic functional calculus. Finally we provide some properties of the calculus.
Redox‐Triggered Self‐Rolling Robust Hydrogel Tubes for Cell Encapsulation
Authors: Liu Lu , Wang Ning , Han Yanjiao , Li Yongmao , Liu Wenguang
Published: December 2013

In this study, mechanically strong hydrogels are synthesized by photopolymerization of 2‐vinyl‐4,6‐diamino‐1,3,5‐triazine, poly(ethylene glycol) methacrylate, and disulfide‐containing cross‐linker, N′N‐bis(acryloyl)cystamine. The bilayer hydrogel with distinct cross‐linking density is shown to self‐roll into a 3D tube, which could still be well reinforced by hydrogen bondings, upon exposing reductants such as 1,4‐dithio‐DL‐threitol (DTT) or L‐glutathione (GSH), because the redox‐induced cleavage of disulfide bonds results in the imbalanced internal shrinking stress between two layers. At an intracellular level of GSH, model L929 cells‐seeded bilayer gel sheet could curl up into a 3D tubular scaffold where the cells maintained good viability.

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“Bio”‐Macromolecules: Polymer‐Protein Conjugates as Emerging Scaffolds for Therapeutics
Authors: Borchmann Dorothee E. , Carberry Tom P. , Weck Marcus
Published: December 2013

Polymer‐protein conjugates are biohybrid macromolecules derived from covalently connecting synthetic polymers with polypeptides. The resulting materials combine the properties of both worlds: chemists can engineer polymers to stabilize proteins, to add functionality, or to enhance activity; whereas biochemists can exploit the specificity and complexity that Nature has bestowed upon its macromolecules. This has led to a wealth of applications, particularly within the realm of biomedicine. Polymer‐protein conjugation has expanded to include scaffolds for drug delivery, tissue engineering, and microbial inhibitors. This feature article reflects upon recent developments in the field and discusses the applications of these hybrids from a biomaterials standpoint.

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Liver fat quantification using a multi‐step adaptive fitting approach with multi‐echo GRE imaging
Authors: Zhong Xiaodong , Nickel Marcel D. , Kannengiesser Stephan A.R. , Dale Brian M. , Kiefer Berthold , Bashir Mustafa R.
Published: December 2013

Purpose

The purpose of this study was to develop a multi‐step adaptive fitting approach for liver proton density fat fraction (PDFF) and
quantification, and to perform an initial validation on a broadly available hardware platform.

Theory and Methods

The proposed method uses a multi‐echo three‐dimensional gradient echo acquisition, with initial guesses for the fat and water signal fractions based on a Dixon decomposition of two selected echoes. Based on magnitude signal equations with a multi‐peak fat spectral model, a multi‐step nonlinear fitting procedure is then performed to adaptively update the fat and water signal fractions and
values. The proposed method was validated using numeric phantoms as ground truth, followed by preliminary clinical validation of PDFF calculations against spectroscopy in 30 patients.

Results

The results of the proposed method agreed well with the ground truth of numerical phantoms, and were relatively insensitive to changes in field strength, field homogeneity, monopolar/bipolar readout, signal to noise ratio, and echo time selections. The in vivo patient study showed excellent consistency between the PDFF values measured with the proposed approach compared with spectroscopy.

Conclusion

This multi‐step adaptive fitting approach performed well in both simulated and initial clinical evaluation, and shows potential in the quantification of hepatic steatosis. Magn Reson Med 72:1353–1365, 2014. © 2013 Wiley Periodicals, Inc.
New results on a stochastic duel game with each force consisting of heterogeneous units
Authors: Lin Kyle Y.
Published: December 2013

Two forces engage in a duel, with each force initially consisting of several heterogeneous units. Each unit can be assigned to fire at any opposing unit, but the kill rate depends on the assignment. As the duel proceeds, each force—knowing which units are still alive in real time—decides dynamically how to assign its fire, in order to maximize the probability of wiping out the opposing force before getting wiped out. It has been shown in the literature that an optimal pure strategy exists for this two‐person zero‐sum game, but computing the optimal strategy remained cumbersome because of the game's huge payoff matrix. This article gives an iterative algorithm to compute the optimal strategy without having to enumerate the entire payoff matrix, and offers some insights into the special case, where one force has only one unit. © 2013 Wiley Periodicals, Inc. Naval Research Logistics 61: 56–65, 2014
Trace Gas Remote Sensing by Lasers
Authors: Lux Oliver , Fritsche Haro , Eichler Hans J.
Published: December 2013

Active remote sensing represents a promising technology to accurately measure the atmospheric concentration of the climate‐relevant trace gases carbon dioxide and methane. For this application, frequency stabilized laser sources with high pulse energy emitting at specific absorption lines around 1.6 μm wavelength are required. While Raman frequency conversion of high power solid‐state laser systems provides sources suitable for CO2 detection, compact resonantly pumped Er:YAG lasers are demonstrated to be feasible for CH4 absorption measurements.
Fast and Selective Against Bacteria
Authors: Neugebauer Ute , Kloß Sandra , Schröder Ulrich‐Christian , Rösch Petra , Popp Jürgen
Published: December 2013

Raman microscopy combined with chemometrics is employed to identify bacteria causing urinary tract infections from urine samples. With this method, a reliable result is obtained within three hours. This is much faster than the current gold standard urine culture as the spectroscopic approach requires no cultivation steps and a few single bacteria are sufficient. In addition, Raman spectroscopy can be employed to determine the antibiotic susceptibility of the bacteria. Thereby it is possible to not only quickly identify the pathogens but also to select the appropriate antibiotics for the patient avoiding inefficient treatment due to resistances. With this complex spectral information, tailored antibiotic therapy is possible already at a much earlier hour.
Rice proteomics: A model system for crop improvement and food security
Authors: Kim Sun Tae , Kim Sang Gon , Agrawal Ganesh Kumar , Kikuchi Shoshi , Rakwal Randeep
Published: December 2013

Rice proteomics has progressed at a tremendous pace since the year 2000, and that has resulted in establishing and understanding the proteomes of tissues, organs, and organelles under both normal and abnormal (adverse) environmental conditions. Established proteomes have also helped in re‐annotating the rice genome and revealing the new role of previously known proteins. The progress of rice proteomics had recognized it as the corner/stepping stone for at least cereal crops. Rice proteomics remains a model system for crops as per its exemplary proteomics research. Proteomics‐based discoveries in rice are likely to be translated in improving crop plants and vice versa against ever‐changing environmental factors. This review comprehensively covers rice proteomics studies from August 2010 to July 2013, with major focus on rice responses to diverse abiotic (drought, salt, oxidative, temperature, nutrient, hormone, metal ions, UV radiation, and ozone) as well as various biotic stresses, especially rice–pathogen interactions. The differentially regulated proteins in response to various abiotic stresses in different tissues have also been summarized, indicating key metabolic and regulatory pathways. We envision a significant role of rice proteomics in addressing the global ground level problem of food security, to meet the demands of the human population which is expected to reach six to nine billion by 2040.
In Vitro Susceptibility of Multidrug Resistant Skin and Wound Pathogens Against Low Temperature Atmospheric Pressure Plasma Jet (APPJ) and Dielectric Barrier Discharge Plasma (DBD)
Authors: Daeschlein Georg , Napp Matthias , von Podewils Sebastian , Lutze Stine , Emmert Steffen , Lange Anja , Klare Ingo , Haase Hermann , Gümbel Denis , von Woedtke Thomas , Jünger Michael
Published: December 2013

Plasma medicine has become an emerging field in medical sciences since cold plasma has demonstrated important antimicrobial properties. As microbial plasma susceptibility data yet are not available, the susceptibility of 194 wound isolates exhibiting multiple antibiotic resistance was tested in vitro to CP and correlated with inhibition zones. Inhibition zones increased in parallel with the number of antibiotic classes to which the tested strain exhibit resistance. CP exhibited strong antimicrobial efficacy against most important clinical skin and wound pathogens in vitro irrespective of multidrug resistance.
Microplasma‐Induce Liquid Chemistry for Stabilizing of Silicon Nanocrystals Optical Properties in Water
Authors: Mitra Somak , Švrček Vladimir , Mariotti Davide , Velusamy Tamilselvan , Matsubara Koiji , Kondo Michio
Published: December 2013

In this report, we demonstrate stabilization of photoluminescence (PL) properties of environmentally and biologically friendly silicon nanocrystals (SiNCs) in water through atmospheric pressure radio‐frequency (RF) microplasma processing at room temperature. The PL of the SiNCs is enhanced after microplasma processing, which involves three‐dimensional engineering of SiNCs directly in water avoiding degradation by surface functionalization. Moreover, we compare the RF microplasma process with direct‐current microplasma processing, whereby the two approaches lead to very similar SiNCs optical properties and surface characteristics. The induced unique chemistry and SiNCs stability in water have wide implications for the SiNCs processability and applications in energy devices, biology and medicine.
Surface evolution of very high dose arsenic implants in silicon formed by plasma immersion ion implantation – a long term study
Authors: Meirer Florian , Demenev Evgeny , Giubertoni Damiano , Vanzetti Lia , Gennaro Salvatore , Fedrizzi Michele , Pepponi Giancarlo , Steinhauser Georg , Vishwanath Vinayak , Foad Majeed , Bersani Massimo
Published: December 2013

The evolution of very high dose arsenic implants in silicon formed by plasma immersion ion implantation and deposition (PIIID) using a non‐pulsed plasma source was studied over a time period of more than one year. The study focused on the effect of arsenolite micro‐crystal formation, enhanced oxidation, and the significant As dose loss from as implanted samples at room temperature. The study was carried out combining analytical evidence from SIMS, XPS, INAA, SEM, and optical microscopy suggesting a two stage process of As dose loss, the first implying arsenolite crystal growth and the second an out‐diffusion. In fact, comparison of samples fabricated using different PIIID parameters showed that crystal growth seems not to be the only process responsible for dose loss. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Application of atomic layer deposited dopant sources for ultra‐shallow doping of silicon
Authors: Kalkofen Bodo , Amusan Akinwumi A. , Lisker Marco , Burte Edmund P.
Published: December 2013

The advanced silicon semiconductor technology requires doping methods for production of ultra‐shallow junctions with sufficiently low sheet resistance. Furthermore, advanced 3‐dimensional topologies may require controlled local doping that cannot be achieved by ionimplantation. Here, the application of the atomic layer deposition (ALD) method for pre‐deposition of dopant sources is presented. Antimony oxide and boron oxide were investigated for such application. Ozone‐based ALD was carried out on silicon wafers by using triethylantimony or tris‐(dimethylamido)borane. Very homogeneous Sb2O5 deposition could be achieved on flat silicon wafers and in trench structures. The thermal stability of antimony oxide layers was investigated by rapid thermal annealing experiments. The layers were not stable above 750 °C. Therefore, this material failed to act as dopant source so far.

In contrast, ultra‐shallow boron doping of silicon from ALD grown boron oxide films was successful. However, pure B2O3 films were highly unstable after exposure to ambient air. The boron oxide films could be protected by thin Sb2O5 or Al2O3 films that were in‐situ grown by ALD. Low temperature ALD of Al2O3 at 50 °C from trimethylaluminium (TMA) and ozone was investigated in detail with respect of its protective effect on boron oxide. Interestingly, it was observed that already one ALD cycle of TMA and O3 resulted in significant increase in stability of the boron oxide in air.

(© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Tuning Cellular Response to Nanoparticles via Surface Chemistry and Aggregation
Authors: Yang Jie An , Lohse Samuel E. , Murphy Catherine J.
Published: December 2013

The aggregation of gold nanoparticles (Au NPs) in cell media is a common phenomenon that can influence NP‐cell interactions. Here, we control Au NP aggregation in cell media and study the impact of Au NP aggregation on human dermal fibroblast (HDF) cells. By first adding Au NPs to fetal bovine serum (FBS) and then subsequently to a buffer, aggregation can be avoided. Aggregation of Au NPs also can be avoided by coating Au NPs with other biomolecules such as lipids. The aggregation state of the Au NPs influences cellular toxicity and Au NP uptake: non‐aggregated cationic Au NPs are four‐fold less toxic to HDF cells than aggregated cationic Au NPs, and the uptake of non‐aggregated anionic citrate Au NPs is three orders of magnitude less than that of aggregated citrate Au NPs. Upon uptake of Au NPs, cellular F‐actin fiber formation is disrupted and actin dots are predominant. When lipid‐coated Au NPs are doped with a fluorescent lipid (F‐lipid) and incubated with HDF cells, the fluorescence from the F‐lipid was found throughout the cell, showing that lipids can dissociate from the Au NP surface upon entering the cell.
The effect of circumcision on young adult sexual function
Authors: Yang Ming‐Hsin , Tsao Chih‐Wei , Wu Sheng‐Tang , Chuang Feng‐Ping , Meng En , Tang Shou‐Hung , Sun Guang‐Huan , Yu Dah‐Shyong , Chang Sun‐Yran , Cha Tai‐Lung
Published: December 2013

Whether sexual function is affected by circumcision is a subject of considerable debate among advocate and opponent opinions. We analyzed the sexual function of young men, and the differences between those who were uncircumcised and circumcised, in Taiwan. A total of 506 patients who received circumcision between January 2009 and March 2011 at the urology department in our center were enrolled. Before circumcision, the patients' sexual performances were evaluated using the International Index of Erectile Function‐5 (IIEF‐5), and the Brief Male Sexual Function Inventory (BMSFI) questionnaires. They were evaluated using the questionnaires again, after a postoperative interval of 90 days. Furthermore, intravaginal ejaculation latency times (IELT) of the patients were also measured. The IELT and scores in five main domains of the BMSFI, and IIEF, before and after circumcision, were analyzed. A total of 442 patients were available for follow up. The mean age was 25.14 ± 4.46 years (range = 19–35 years). The differences in the BMSFI scores were statistically significant (p < 0.001), especially in increasing sex drive after circumcision (p < 0.001). The IIEF‐5 score showed no statistically difference before and after circumcision (p = 0.141). However, after the circumcision, the participants had more erection confidence (p < 0.001), more difficulty in maintaining erections in completing intercourse (p = 0.01), and showed lower IELT scores (p = 0.06). The sexual performance, especially with regards to sex drive and mental erection confidence, seemed to have improved among the patients after circumcision. Our findings may help urologists to better counsel young men receiving circumcisions.
A Variational Method in Out-of-Equilibrium Physical Systems
Authors: Pinheiro Mario J.
Published: December 2013

We propose a new variational principle for out-of-equilibrium dynamic systems that are fundamentally based on the method of Lagrange multipliers applied to the total entropy of an ensemble of particles. However, we use the fundamental equation of thermodynamics "Equation missing"on differential forms, consideringUandSas 0-forms. We obtain a set of two first order differential equations that reveal the same formal symplectic structure shared by classical mechanics, fluid mechanics and thermodynamics. From this approach, a topological torsion current emerges of the form "Equation missing", whereAjand ωkdenote the components of the vector potential (gravitational and/or electromagnetic) and where ω denotes the angular velocity of the accelerated frame. We derive a special form of the Umov-Poynting theorem for rotating gravito-electromagnetic systems. The variational method is then applied to clarify the working mechanism of particular devices.
Counterion effects in the catalytic stereoselective synthesis of 2,3′-pyrrolidinyl spirooxindoles
Authors: MacDonald Jacob P. , Shupe Benjamin H. , Schreiber John D. , Franz Annaliese K.
Published: December 2013

A Lewis acid-catalyzed stereoselective [3+2] annulation of crotylsilanes with iminooxindoles is reported to access 2,3′-pyrrolidinyl spirooxindoles with four stereocenters.
The formation mechanism and photocatalytic activity of hierarchical NiAl–LDH films on an Al substrate prepared under acidic conditions
Authors: Xue Li , Cheng Yingzhi , Sun Xiuyu , Zhou Ziyan , Xiao Xiaoling , Hu Zhongbo , Liu Xiangfeng
Published: December 2013

NiAl–LDH films with enhanced photocatalytic activity were prepared by immersion of an Al substrate in Ni2+-containing solution under strong acidic conditions.
It's all about Me: methyl-induced control of coordination stereochemistry by a flexible tridentate N,C,N′ ligand
Authors: Kariuki Benson M. , Platts James A. , Newman Paul D.
Published: December 2013

The introduction of a single methyl group on one of the chelate arms of a dipyridyl-NHC ligand has been achieved stereoselectively and the resultant tridentate ligand (S-LMe) coordinated to Rh(i), Ir(i) and Ni(ii) to give single diastereomers.
A three dimensional SiOx/C@RGO nanocomposite as a high energy anode material for lithium-ion batteries
Authors: Guo Chenfeng , Wang Dianlong , Liu Tiefeng , Zhu Junsheng , Lang Xiaoshi
Published: December 2013

For the first time, a co-modification strategy using carbon and RGO was carried out to improve the electrochemical performance of SiO-based materials for their use in LIBs.
Nafion-functionalized electrospun poly(vinylidene fluoride) (PVDF) nanofibers for high performance proton exchange membranes in fuel cells
Authors: Li Hsieh-Yu , Liu Ying-Ling
Published: December 2013

Nafion-functionalized electrospun poly(vinylidene fluoride) nanofibers show high performance in preparation of proton exchange membranes for fuel cells.
A transmembrane serine residue in the Rot1 protein is essential for yeast cell viability
Authors: Martínez-Garay Carlos A. , Juanes M. Angeles , Igual J. Carlos , Mingarro Ismael , Bañó M. Carmen
Published: December 2013

Polar residues are present in TM (transmembrane) helices and may influence the folding or association of membrane proteins. In the present study, we use an in vivo approach to analyse the functional and structural roles for amino acids in membrane-spanning motifs using the Rot1 (reversal of Tor2 lethality 1) protein as a model. Rot1 is an essential membrane protein in Saccharomyces cerevisiae and it contains a single TM domain. An alanine insertion scanning analysis of this TM helix revealed that the integrity of the central domain is essential for protein function. We identified a critical serine residue inside the helix that plays an essential role in maintaining cell viability in S. cerevisiae. Replacement of the serine residue at position 250 with a broad variety of amino acids did not affect protein targeting and location, but completely disrupted protein function causing cell death. Interestingly, substitution of the serine residue by threonine resulted in sustained cell viability, demonstrating that the hydroxy group of the TM serine side chain plays a critical role in protein function. The results of the present study indicate that Rot1 needs the TM Ser250 to interact with other membrane components and exert its functional role, avoiding exposure of the serine hydrogen-bonding group at the lipid-exposed surface.
Identification of four novel serum protein biomarkers in sepsis patients encoded by target genes of sepsis-related miRNAs
Authors: Wang Hui-juan , Wang Bao-zeng , Zhang Peng-jun , Deng Jie , Zhao Zhi-rui , Zhang Xin , Xiao Kun , Feng Dan , Jia Yan-hong , Liu You-ning , Xie Li-xin
Published: December 2013

The goal of the present study was to identify novel protein biomarkers from the target genes of six serum miRNAs that we identified previously in patients with sepsis. The target genes were predicted by bioinformatics analysis; the levels of the respective proteins in the sera of patients with sepsis were detected by ELISA. ACVR2A (activin A receptor, type IIA), FOXO1 (forkhead box O1), IHH (Indian hedgehog), STK4 (serine/threonine kinase 4) and DUSP3 (dual specificity phosphatase 3) were predicted to be the targets of the six miRNAs, and their encoded proteins were used for biomarker identification. Levels of ACVR2A (P<0.01) and FOXO1 (P<0.01) were significantly different among normal controls, patients with sepsis, patients with severe sepsis and patients with septic shock. Furthermore, levels of ACVR2A (P=0.025), FOXO1 (P<0.001), IHH (P=0.001) and STK4 (P=0.001) were differentially expressed in survivors and non-survivors. DUSP3 levels were not significantly different between any groups. Conjoin analysis of the four differentially expressed proteins showed that the area under the curve of the predictive probabilities was 0.875 [95% CI (confidence interval): 0.785–0.965], which was higher than the SOFA (Sequential Organ Failure Assessment) and APACHE II (Acute Physiology and Chronic Health Evaluation II) scores. When the value of predictive probabilities was 0.449, the four proteins yielded a sensitivity of 68% and a specificity of 91%. Dynamic changes in ACVR2A, FOXO1 and IHH levels showed differential expression between survivors and non-survivors at all time points. On the basis of a combined analysis of the four identified proteins, their predictive value of 28-day mortality of patients with sepsis was better than the SOFA or APACHE II scores.
Analysis and design of a new fountain codec under belief propagation
Authors: Mirrezaei Seyed Masoud , Faez Karim , Yousefi Shahram
Published: December 2013

Error‐prone patterns have been extensively studied for low‐density parity‐check codes yet they have never been fully explored for generator‐based ‘Fountain codes’. It is shown here that these phenomena are related to certain combinatorial structures within the Tanner graph (TG) representation of the code, previously termed absorbing sets. The authors systematically define the ‘absorbing sets’ in the generator‐based TG of a code. They then demonstrate how these substructures are damaging to the ‘realised rate, delay’ and ‘decoding cost’ of Fountain codes particularly at low error rates. They further analyse the existence probability of certain absorbing sets and propose a new encoder/decoder pair forming a new family of Fountain codes. The authors experimental results show that these new codecs lead to improvements in all system features. Typical gains for Luby‐transform codes include 20% reduction in the decoding complexity and simultaneous coding gains of 0.6 and 0.9 dB at bit error rates of 10−5 and 10−6, respectively. As such, this work takes a step towards better rateless code design and construction.
Downlink performance limitations of cellular systems with coordinated base stations and mismatched precoder
Authors: Rosas Fernando , Herrera Lurys , Oberli Christian , Manolakis Konstantinos , Jungnickel Volker
Published: December 2013

Coordination of base stations is a promising technique for reducing inter‐cell interference in next‐generation cellular systems. For the downlink of such systems, the authors study the degradation of zero‐forcing precoded transmissions caused by imperfect channel estimation and channel variation over time. They derive exact expressions for the mean power of the desired signal received by an arbitrary user and of the interference caused by the mismatched precoder. By using these expressions, they show that for attaining a given signal‐to‐interference power ratio (SIR) these systems are limited by a maximum feedback delay of updated channel state information. Finally, they present a procedure to calculate the maximum tolerable feedback delay and to determine the separation between the non‐precoded pilot symbols for guaranteeing a desired SIR.
Beam steering with graded index photonic crystal lens and liquid crystal
Authors: Bahari Babak , Rashed‐Mohassel Jalil
Published: December 2013

In this numerical study, a new compact and tunable beam‐steering device composed of graded index photonic crystal lens and liquid crystal material has been presented and demonstrated. The beam‐steering device can work in two modes: First, incident single wavelength beam steers by tuning the refractive index of the liquid crystal material. Second, by fixing the refractive index of the liquid crystal material, incident multi‐wavelength beam steers with different off‐axis angles for each wavelength. The numerical simulations with finite‐difference time‐domain method reveal that wide‐angle, ± 28.4°, beam steering can be achieved when the length of the liquid crystal layer equals 5.17 μm. Moreover, the wavelengths over λ = 1.518–1.553 μm or λ = 1.487–1.518 μm can be steered to different angles. A special characteristic of the presented structure gives an opportunity to be used as an efficient element in a high integrated optical device for miniaturisation and tuning purposes.
A scalable, fast, and multichannel arbitrary waveform generator
Authors: Baig M. T. , Johanning M. , Wiese A. , Heidbrink S. , Ziolkowski M. , Wunderlich C.
Published: December 2013

This article reports on the development of a multichannel arbitrary waveform generator that simultaneously generates arbitrary voltage waveforms on 24 independent channels with a dynamic update rate of up to 25 Msps. A real-time execution of a single waveform and/or sequence of multiple waveforms in succession, with a user programmable arbitrary sequence order is provided under the control of a stand-alone sequencer circuit implemented using a field programmable gate array. The device is operated using an internal clock and can be synced to other devices by means of transistor-transistor logic (TTL) pulses. The device can provide up to 24 independent voltages in the range of up to ± 9 V with a dynamic update-rate of up to 25 Msps and a power consumption of less than 35 W. Every channel can be programmed for 16 independent arbitrary waveforms that can be accessed during run time with a minimum switching delay of 160 ns. The device has a low-noise of 250 μVrms and provides a stable long-term operation with a drift rate below 10 μV/min and a maximum deviation less than ± 300 μVpp over a period of 2 h.
A new ab initio potential energy surface for the collisional excitation of HCN by para- and ortho-H2
Authors: Denis-Alpizar Otoniel , Kalugina Yulia , Stoecklin Thierry , Vera Mario Hernández , Lique François
Published: December 2013

We present a new four-dimensional potential energy surface for the collisional excitation of HCN by H2. Ab initio calculations of the HCN–H2 van der Waals complex, considering both molecules as rigid rotors, were carried out at the explicitly correlated coupled cluster with single, double, and perturbative triple excitations [CCSD(T)-F12a] level of theory using an augmented correlation-consistent triple zeta (aVTZ) basis set. The equilibrium structure is linear HCN–H2 with the nitrogen pointing towards H2 at an intermolecular separation of 7.20 a0. The corresponding well depth is −195.20 cm−1. A secondary minimum of −183.59 cm−1 was found for a T-shape configuration with the H of HCN pointing to the center of mass of H2. We also determine the rovibrational energy levels of the HCN–para-H2 and HCN–ortho-H2 complexes. The calculated dissociation energies for the para and ortho complexes are 37.79 cm−1 and 60.26 cm−1, respectively. The calculated ro-vibrational transitions in the HCN–H2 complex are found to agree by more than 0.5% with the available experimental data, confirming the accuracy of the potential energy surface.
Deep-level traps induced dark currents in extended wavelength InxGa1−xAs/InP photodetector
Authors: Ji Xiaoli , Liu Baiqing , Xu Yue , Tang Hengjing , Li Xue , Gong HaiMei , Shen Bo , Yang Xuelin , Han Ping , Yan Feng
Published: December 2013

The dark current mechanism of extended wavelength InxGa1−xAs photo-detectors is still a debated issue. In this paper, the deep-level transient spectroscopy (DLTS) and dark current characteristics of InxGa1−xAs/InP detectors are investigated. Using trap parameters obtained from DLTS measurement, the device simulations of current-voltage characteristics are carried out by Silvaco Altas. The results reveal that the dark current at the low reverse bias voltage is associated with deep level trap induced trap assisted tunneling and Shockley-Read-Hall generation mechanism. The reduction of the deep level trap concentration in InxGa1−xAs absorption layer could dramatically suppress the dark current near zero bias in extended wavelength InxGa1−xAs/InP detectors.
Microscopic scale investigation of piezoelectric properties of lead-free alkaline niobates
Authors: Machado R. , Sepliarsky M. , Stachiotti M. G.
Published: December 2013

A first-principles-based technique is used to investigate the electromechanical properties of lead-free alkaline niobates. In particular, we study the structural and piezoelectric properties of LixK1−xNbO3 which is taken as a prototypical solid solution. We show that the system develops an orthorhombic to tetragonal polymorphic phase transition at room temperature for a Li concentration of 4.5%. We showed that not only the phase coexistence region is relevant for the enhancement of the piezoelectric properties but also the off-center Li impurities play an important role in the improvement of the electromechanical response.
Control of plasma profile in microwave discharges via inverse-problem approach
Authors: Yasaka Yasuyoshi , Tobita Naoki , Tsuji Akihiro
Published: December 2013

In the manufacturing process of semiconductors, plasma processing is an essential technology, and the plasma used in the process is required to be of high density, low temperature, large diameter, and high uniformity. This research focuses on the microwave-excited plasma that meets these needs, and the research target is a spatial profile control. Two novel techniques are introduced to control the uniformity; one is a segmented slot antenna that can change radial distribution of the radiated field during operation, and the other is a hyper simulator that can predict microwave power distribution necessary for a desired radial density profile. The control system including these techniques provides a method of controlling radial profiles of the microwave plasma via inverse-problem approach, and is investigated numerically and experimentally.
Modelling the inhomogeneous SiC Schottky interface
Authors: Gammon P. M. , Pérez-Tomás A. , Shah V. A. , Vavasour O. , Donchev E. , Pang J. S. , Myronov M. , Fisher C. A. , Jennings M. R. , Leadley D. R. , Mawby P. A.
Published: December 2013

For the first time, the I-V-T dataset of a Schottky diode has been accurately modelled, parameterised, and fully fit, incorporating the effects of interface inhomogeneity, patch pinch-off and resistance, and ideality factors that are both heavily temperature and voltage dependent. A Ni/SiC Schottky diode is characterised at 2 K intervals from 20 to 320 K, which, at room temperature, displays low ideality factors (n < 1.01) that suggest that these diodes may be homogeneous. However, at cryogenic temperatures, excessively high (n > 8), voltage dependent ideality factors and evidence of the so-called “thermionic field emission effect” within a T0-plot, suggest significant inhomogeneity. Two models are used, each derived from Tung's original interactive parallel conduction treatment of barrier height inhomogeneity that can reproduce these commonly seen effects in single temperature I-V traces. The first model incorporates patch pinch-off effects and produces accurate and reliable fits above around 150 K, and at current densities lower than 10−5 A cm−2. Outside this region, we show that resistive effects within a given patch are responsible for the excessive ideality factors, and a second simplified model incorporating these resistive effects as well as pinch-off accurately reproduces the entire temperature range. Analysis of these fitting parameters reduces confidence in those fits above 230 K, and questions are raised about the physical interpretation of the fitting parameters. Despite this, both methods used are shown to be useful tools for accurately reproducing I-V-T data over a large temperature range.
Infrared optical properties of α-alumina with the approach to melting: γ-like tetrahedral structure and small polaron conduction
Authors: Brun J. F. , del Campo L. , De Sousa Meneses D. , Echegut P.
Published: December 2013

The normal spectral emittance of α-Al2O3 single crystal has been measured from room temperature up to the liquid state and from 20 cm−1 up to 10 000 cm−1, in two polarization configurations. The spectra were fitted with a semi-quantum dielectric function model. AlO4 structure units are revealed within the phonon spectral range more than a hundred degrees below the melting point when heating from the solid state. In parallel, the anomalous increase of emittance observed within the transparency spectral range with the approach to melting appears strongly correlated. Implications on the electronic structure are discussed: the existence of small polaron conduction is suggested which has never been mentioned before.
Physical activity levels during pregnancy and gestational weight gain among women who are overweight or obese
Authors: Sui Zhixian , Moran Lisa J. , Dodd Jodie M.
Published: December 2013

Issue addressed

There is contradictory research assessing physical activity patterns during pregnancy and postpartum among women who are overweight or obese. The aim of this study was to evaluate physical activity among overweight and obese women over the course of pregnancy and the initial postpartum period.

Methods

Three hundred and five overweight or obese pregnant women completed physical‐activity questionnaires at three time points during pregnancy and at 4‐months postpartum.

Results

Physical activity declined between early pregnancy and 28‐weeks gestation (P < 0.001) and declined further at 36‐weeks gestation (P < 0.001) before increasing significantly at 4‐months postpartum (P < 0.001). However, reported activity at 4‐months postpartum remained significantly lower than that reported in early pregnancy (P < 0.001). There was no significant difference either cross‐sectionally or for changes over pregnancy and postpartum for total levels or categories of physical activity for women with different body mass index (BMI) or gestational weight gain (GWG). BMI was the only independent predictor of the change in total physical activity over the study and GWG, with women with higher BMI having larger decline of physical activity (β = 0.114, s.e. = 0.750, P = 0.032) and less GWG (β = −0.253, s.e. = 0.063, P < 0.001).

Conclusions

Physical activity declined significantly between early pregnancy and 28‐weeks gestation, with a further decline to 36‐weeks gestation. At 4‐months postpartum, physical activity significantly increased but not to the level of that reported at early pregnancy.

So what?

The promotion of appropriate physical activity should be implemented early in pregnancy and postpartum to prevent the decline in activity we have observed in overweight and obese women. Future research should also explore the barriers and enablers to women engaging in exercise during pregnancy and the postpartum period.
Task-switching cost and repetition priming: Two overlooked confounds in the fixed-set procedure of the Sternberg paradigm and how they affect memory set-size effects
Authors: Jou Jerwen
Published: December 2013

Subjects performed Sternberg-type memory recognition tasks (Sternberg paradigm) in four experiments. Category-instance names were used as learning and testing materials. Sternberg's original experiments demonstrated a linear relation between reaction time (RT) and memory-set size (MSS). A few later studies found no relation, and other studies found a nonlinear relation (logarithmic) between the two variables. These deviations were used as evidence undermining Sternberg's serial scan theory. This study identified two confounding variables in the fixed-set procedure of the paradigm (where multiple probes are presented at test for a learned memory set) that could generate a MSS RT function that was either flat or logarithmic rather than linearly increasing. These two confounding variables were task-switching cost and repetition priming. The former factor worked against smaller memory sets and in favour of larger sets whereas the latter factor worked in the opposite way. Results demonstrated that a null or a logarithmic RT-to-MSS relation could be the artefact of the combined effects of these two variables. The Sternberg paradigm has been used widely in memory research, and a thorough understanding of the subtle methodological pitfalls is crucial. It is suggested that a varied-set procedure (where only one probe is presented at test for a learned memory set) is a more contamination-free procedure for measuring the MSS effects, and that if a fixed-set procedure is used, it is worthwhile examining the RT function of the very first trials across the MSSs, which are presumably relatively free of contamination by the subsequent trials.
FSGS3/CD2AP is a barbed-end capping protein that stabilizes actin and strengthens adherens junctions
Authors: Tang Vivian W. , Brieher William M.
Published: December 2013

By combining in vitro reconstitution biochemistry with a cross-linking approach, we have identified focal segmental glomerulosclerosis 3/CD2-associated protein (FSGS3/CD2AP) as a novel actin barbed-end capping protein responsible for actin stability at the adherens junction. FSGS3/CD2AP colocalizes with E-cadherin and α-actinin-4 at the apical junction in polarized Madin-Darby canine kidney (MDCK) cells. Knockdown of FSGS3/CD2AP compromised actin stability and decreased actin accumulation at the adherens junction. Using a novel apparatus to apply mechanical stress to cell–cell junctions, we showed that knockdown of FSGS3/CD2AP compromised adhesive strength, resulting in tearing between cells and disruption of barrier function. Our results reveal a novel function of FSGS3/CD2AP and a previously unrecognized role of barbed-end capping in junctional actin dynamics. Our study underscores the complexity of actin regulation at cell–cell contacts that involves actin activators, inhibitors, and stabilizers to control adhesive strength, epithelial behavior, and permeability barrier integrity.
Trina Schroer: What’s cooking on dynactin
Authors: Sedwick Caitlin
Published: December 2013

Schroer studies the composition and activity of dynactin.
Crystal structure analysis and sublimation thermodynamics of bicyclo derivatives of a neuroprotector family
Authors: Surov Artem O. , Proshin Alexey N. , Perlovich German L.
Published: December 2013

The crystal structures of three new structurally related drug-like bicyclo derivatives are correlated with measured thermodynamic quantities for their sublimation and melting processes. The sublimation thermodynamics are determined using the temperature dependencies of the vapour pressure, and the melting processes are examined using differential scanning calorimetry. The three compounds contain a commonN-(3-thia-1-azabicyclo[3.3.1]non-2-ylidene)aniline core, with either a CH3, F or CF3substituent at the 4-position of the aniline ring. Lattice energy calculations are made using both the PIXEL and Coulomb–London–Pauli (CLP) models, and the conformational flexibility of the molecules is examined using gas-phase density functional theory (DFT) calculations. The experimentally measured crystal lattice energies (ΔH0sub) decrease in the order: CH3> F > CF3. The calculated lattice energies using the PIXEL approach are in good agreement with the experimental values, and the partitioned intermolecular interaction energies suggest that dispersion contributions dominate the crystal structures of all three compounds. The sublimation energies and melting points are inversely correlated for the three molecules, with the melting points increasing in the order CF3< F < CH3.
Distortions of a flexible metal-organic framework from substituted pendant ligands
Authors: Munn Alexis S. , Clarkson Guy J. , Walton Richard I.
Published: December 2013

Four new variants of the 1,4-benzenedicarboxylate MIL-53 structure have been prepared for CoIIunder solvothermal conditions and their structures solved and refined from single-crystal X-ray data. All materials contain pendant pyridine-N-oxide ligands that bridge pairs of CoIIatoms in the inorganic backbone of the structureviaO. By the use of the ligands 3-bromopyridine-N-oxide, 4-methoxypyridine-N-oxide, isoquinoline-N-oxide and 4-phenylpyridine-N-oxide, materials are prepared with the same topology but distinct structures. These illustrate how the MIL-53 structure is able to distort to accommodate the bulk of the various substituents on the pyridine ring. The bulkiest pendant ligand, 4-phenylpyridine-N-oxide, results in a distortion of the diamond-shaped channels in an opposite sense to that seen previously in expanded forms of the parent MIL-53 structure. By comparison with published crystal structures for MIL-53 with various occluded guests, the structural distortions that take place to accommodate the pendant ligands are quantified and it is shown how a twisting of the 1,4-benzenedicarboxylate ligand, instead of a hinging about the μ2-carboxylate-metal connection, allows the new structures that are observed.
Spatial analyses for nonoverlapping objects with size variations and their application to coral communities
Authors: Muko Soyoka , Shimatani Ichiro K. , Nozawa Yoko
Published: December 2013

Spatial distributions of individuals are conventionally analysed by representing objects as dimensionless points, in which spatial statistics are based on centre‐to‐centre distances.

However, if organisms expand without overlapping and show size variations, such as is the case for encrusting corals, interobject spacing is crucial for spatial associations where interactions occur.

We introduced new pairwise statistics using minimum distances between objects and demonstrated their utility when examining encrusting coral community data. We also calculated the conventional point process statistics and the grid‐based statistics to clarify the advantages and limitations of each spatial statistical method. For simplicity, coral colonies were approximated by disks in these demonstrations.

Focusing on short‐distance effects, the use of minimum distances revealed that almost all coral genera were aggregated at a scale of 1–25 cm. However, when fragmented colonies (ramets) were treated as a genet, a genet‐level analysis indicated weak or no aggregation, suggesting that most corals were randomly distributed and that fragmentation was the primary cause of colony aggregations. In contrast, point process statistics showed larger aggregation scales, presumably because centre‐to‐centre distances included both intercolony spacing and colony sizes (radius). The grid‐based statistics were able to quantify the patch (aggregation) scale of colonies, but the scale was strongly affected by the colony size.

Our approach quantitatively showed repulsive effects between an aggressive genus and a competitively weak genus, while the grid‐based statistics (covariance function) also showed repulsion although the spatial scale indicated from the statistics was not directly interpretable in terms of ecological meaning.

The use of minimum distances together with previously proposed spatial statistics helped us to extend our understanding of the spatial patterns of nonoverlapping objects that vary in size and the associated specific scales.