bluuebunny/crossref_metadata_2025 huggingface dataset:
Algebraic Reynolds stress modeling of turbulence subject to rapid homogeneous and non-homogeneous compression or expansion
Authors: Grigoriev I. A. , Wallin S. , Brethouwer G. , Grundestam O. , Johansson A. V.
Published: February 2016

A recently developed explicit algebraic Reynolds stress model (EARSM) by Grigoriev et al. [“A realizable explicit algebraic Reynolds stress model for compressible turbulent flow with significant mean dilatation,” Phys. Fluids 25(10), 105112 (2013)] and the related differential Reynolds stress model (DRSM) are used to investigate the influence of homogeneous shear and compression on the evolution of turbulence in the limit of rapid distortion theory (RDT). The DRSM predictions of the turbulence kinetic energy evolution are in reasonable agreement with RDT while the evolution of diagonal components of anisotropy correctly captures the essential features, which is not the case for standard compressible extensions of DRSMs. The EARSM is shown to give a realizable anisotropy tensor and a correct trend of the growth of turbulence kinetic energy K, which saturates at a power law growth versus compression ratio, as well as retaining a normalized strain in the RDT regime. In contrast, an eddy-viscosity model results in a rapid exponential growth of K and excludes both realizability and high magnitude of the strain rate. We illustrate the importance of using a proper algebraic treatment of EARSM in systems with high values of dilatation and vorticity but low shear. A homogeneously compressed and rotating gas cloud with cylindrical symmetry, related to astrophysical flows and swirling supercritical flows, was investigated too. We also outline the extension of DRSM and EARSM to include the effect of non-homogeneous density coupled with “local mean acceleration” which can be important for, e.g., stratified flows or flows with heat release. A fixed-point analysis of direct numerical simulation data of combustion in a wall-jet flow demonstrates that our model gives quantitatively correct predictions of both streamwise and cross-stream components of turbulent density flux as well as their influence on the anisotropies. In summary, we believe that our approach, based on a proper formulation of the rapid pressure-strain correlation and accounting for the coupling with turbulent density flux, can be an important element in CFD tools for compressible flows.
Current-driven antivortex core resonance measured by the rectifying effect
Authors: Goto Minori , Nozaki Yukio
Published: February 2016

We demonstrate the current-driven resonance of a single antivortex core confined in a cross-shaped Ni81Fe19 wire. The antivortex core dynamics can be excited purely by spin transfer torque; therefore, it is significant to understand the current-induced magnetization dynamics. The antivortex core resonance can be measured from the frequency dependence of a rectified voltage generated by an alternating current application. We found that the resonance frequency and peak amplitude greatly depend on the external magnetic field. This result is in good agreement with micromagnetic simulation.
Investigation into the role of the Laurent property in integrability
Authors: Mase Takafumi
Published: February 2016

We study the Laurent property for autonomous and nonautonomous discrete equations. First we show, without relying on the caterpillar lemma, the Laurent property for the Hirota-Miwa and the discrete BKP (or so-called Miwa) equations. Next we introduce the notion of reductions and gauge transformations for discrete bilinear equations and we prove that these preserve the Laurent property. Using these two techniques, we obtain the explicit condition on the coefficients of a nonautonomous discrete bilinear equation for it to possess the Laurent property. Finally, we study the denominators of the iterates of an equation with the Laurent property and we show that any reduction to a mapping on a one-dimensional lattice of a nonautonomous Hirota-Miwa equation or discrete BKP equation, with the Laurent property, has zero algebraic entropy.
Modeling the effect of elastic point contact on dynamic response
Authors: Photiadis Douglas M. , Goldstein David J. , Willey Jefferson M.
Published: February 2016

We present a general, theoretical model describing the three-dimensional elastic behavior of point contacts. We provide a prescription for employing the model in a variety of physical systems and describe in detail how the model enables the use of lower-dimensional dynamic models while including approximate three-dimensional behavior of elastic point contacts. We conduct a series of experiments to validate the model for extensional and cantilever oscillators, and find good agreement between our measurements and the predictions of the model. We observe that the phenomenological effects of elastic point contacts can be significant and believe that our model will be useful to a broad range of research and engineering disciplines.
Research on calibration method of relative infrared radiometer
Authors: Yang Sen , Li Chengwei
Published: February 2016

The Relative Infrared Radiometer (RIR) is commonly used to measure the irradiance of the Infrared Target Simulator (ITS), and the calibration of the RIR is central for the measurement accuracy. RIR calibration is conventionally performed using the Radiance Based (RB) calibration method or Irradiance Based (IB) calibration method, and the relationship between the radiation of standard source and the response of RIR is determined by curve fitting. One limitation existing in the calibration of RIR is the undesirable calibration voltage fluctuation in single measurement or in the reproducibility measurement, which reduces the calibration reproducibility and irradiance measurement accuracy. To address this limitation, the Equivalent Blackbody Temperature Based (EBTB) calibration method is proposed for the calibration of RIR. The purpose of this study is to compare the proposed EBTB calibration method with conventional RB and IB calibration methods. The comparison and experiment results have shown that the EBTB calibration method is not only able to provide comparable correlation between radiation and response to other calibration methods (IB and RB) in the irradiance measurement but also reduces the influence of calibration voltage fluctuation on the irradiance measurement result, which improves the calibration reproducibility and irradiance measurement accuracy.
Improved room-temperature luminescence of core-shell InGaAs/GaAs nanopillars via lattice-matched passivation
Authors: Komolibus Katarzyna , Scofield Adam C. , Gradkowski Kamil , Ochalski Tomasz J. , Kim Hyunseok , Huffaker Diana L. , Huyet Guillaume
Published: February 2016

Optical properties of GaAs/InGaAs/GaAs nanopillars (NPs) grown on GaAs(111)B were investigated. Employment of a mask-etching technique allowed for an accurate control over the geometry of NP arrays in terms of both their diameter and separation. This work describes both the steady-state and time-resolved photoluminescence of these structures as a function of the ensemble geometry, composition of the insert, and various shell compounds. The effects of the NP geometry on a parasitic radiative recombination channel, originating from an overgrown lateral sidewall layer, are discussed. Optical characterization reveals a profound influence of the core-shell lattice mismatch on the carrier lifetime and emission quenching at room temperature. When the lattice-matching conditions are satisfied, an efficient emission from the NP arrays at room temperature and below the band-gap of silicon is observed, clearly highlighting their potential application as emitters in optical interconnects integrated with silicon platforms.
A new method to induce molecular low bias negative differential resistance with multi-peaks
Authors: Min Y. , Zhong C. G. , Dong Z. C. , Zhao Z. Y. , Zhou P. X. , Yao K. L.
Published: February 2016

According to a first-principles study of the transport properties of two thiolated anthracene-9,10-diono molecules sandwiching ethyl, a new method to induce molecular low bias negative differential resistance with multi-peaks for strong n- or p-type molecules is proposed. The anthracene-9,10-diono molecule shows strong n-type characteristics when in contact with Au and Ag electrodes via a thiolate. The multiple negative differential resistance effect originated from the molecule–electrode couple is different between Ag and Au electrodes. Our investigations may promise potential for applications in molecular devices with low power dissipation and multifunction in the future.
Qualitative properties of solutions for nonlinear Schrödinger equations with nonlinear boundary conditions on the half-line
Authors: Kalantarov Varga K. , Özsarı Türker
Published: February 2016

In this paper, we study the interaction between a nonlinear focusing Robin type boundary source, a nonlinear defocusing interior source, and a weak damping term for nonlinear Schrödinger equations posed on the infinite half-line. We construct solutions with negative initial energy satisfying a certain set of conditions which blow-up in finite time in the H1-sense. We obtain a sufficient condition relating the powers of nonlinearities present in the model which allows construction of blow-up solutions. In addition to the blow-up property, we also discuss the stabilization property and the critical exponent for this model.
Low leakage ZrO2 based capacitors for sub 20 nm dynamic random access memory technology nodes
Authors: Pešić Milan , Knebel Steve , Geyer Maximilian , Schmelzer Sebastian , Böttger Ulrich , Kolomiiets Nadiia , Afanas'ev Valeri V. , Cho Kyuho , Jung Changhwa , Chang Jaewan , Lim Hanjin , Mikolajick Thomas , Schroeder Uwe
Published: February 2016

During dynamic random access memory (DRAM) capacitor scaling, a lot of effort was put searching for new material stacks to overcome the scaling limitations of the current material stack, such as leakage and sufficient capacitance. In this study, very promising results for a SrTiO3 based capacitor with a record low capacitance equivalent thickness value of 0.2 nm at target leakage current are presented. Due to the material properties of SrTiO3 films (high vacancy concentration and low band gap), which are leading to an increased leakage current, a physical thickness of at least 8 nm is required at target leakage specifications. However, this physical thickness would not fit into an 18 nm DRAM structure. Therefore, two different new approaches to develop a new ZrO2 based DRAM capacitor stack by changing the inter-layer material from Al2O3 to SrO and the exchange of the top electrode material from TiN to Pt are presented. A combination of these two approaches leads to a capacitance equivalent thickness value of 0.47 nm. Most importantly, the physical thickness of <5 nm for the dielectric stack is in accordance with the target specifications. Detailed evaluation of the leakage current characteristics leads to a capacitor model which allows the prediction of the electrical behavior with thickness scaling.
Identification of the dominant photochemical pathways and mechanistic insights to the ultrafast ligand exchange of Fe(CO)5 to Fe(CO)4EtOH
Authors: Kunnus K. , Josefsson I. , Rajkovic I. , Schreck S. , Quevedo W. , Beye M. , Weniger C. , Grübel S. , Scholz M. , Nordlund D. , Zhang W. , Hartsock R. W. , Gaffney K. J. , Schlotter W. F. , Turner J. J. , Kennedy B. , Hennies F. , de Groot F. M. F. , Techert S. , Odelius M. , Wernet Ph. , Föhlisch A.
Published: February 2016

We utilized femtosecond time-resolved resonant inelastic X-ray scattering and ab initio theory to study the transient electronic structure and the photoinduced molecular dynamics of a model metal carbonyl photocatalyst Fe(CO)5 in ethanol solution. We propose mechanistic explanation for the parallel ultrafast intra-molecular spin crossover and ligation of the Fe(CO)4 which are observed following a charge transfer photoexcitation of Fe(CO)5 as reported in our previous study [Wernet et al., Nature 520, 78 (2015)]. We find that branching of the reaction pathway likely happens in the 1A1 state of Fe(CO)4. A sub-picosecond time constant of the spin crossover from 1B2 to 3B2 is rationalized by the proposed 1B2 → 1A1 → 3B2 mechanism. Ultrafast ligation of the 1B2 Fe(CO)4 state is significantly faster than the spin-forbidden and diffusion limited ligation process occurring from the 3B2 Fe(CO)4 ground state that has been observed in the previous studies. We propose that the ultrafast ligation occurs via 1B2 → 1A1 → 1A′ Fe(CO)4EtOH pathway and the time scale of the 1A1 Fe(CO)4 state ligation is governed by the solute-solvent collision frequency. Our study emphasizes the importance of understanding the interaction of molecular excited states with the surrounding environment to explain the relaxation pathways of photoexcited metal carbonyls in solution.
Determination of optimal ionic liquid for organic single-crystal field-effect transistors
Authors: Ono S. , Miwa K. , Seki S.
Published: February 2016

We investigate organic single-crystal field-effect transistors with various ionic liquids as gate dielectric. We find that the mobility of the field-effect transistors for both p-type and n-type organic semiconductors increases with decreasing total capacitance of the ionic liquid. However, it does not depend on the ion species at the interface between the organic semiconductor and the ionic liquid. By choosing an appropriate ionic liquid, a high carrier mobility of 12.4 cm2/V s in rubrene single crystals (p-type) and 0.13 cm2/V s in 7.7.8.8-Tetracyanoquinodimethane single crystals (n-type) are achieved. This study clarifies the influence of ionic liquids on the device performance of organic field-effect transistors and shows a way to maximize carrier mobility at the solid/liquid interface.
High-voltage vertical GaN Schottky diode enabled by low-carbon metal-organic chemical vapor deposition growth
Authors: Cao Y. , Chu R. , Li R. , Chen M. , Chang R. , Hughes B.
Published: February 2016

Vertical GaN Schottky barrier diode (SBD) structures were grown by metal-organic chemical vapor deposition on free-standing GaN substrates. The carbon doping effect on SBD performance was studied by adjusting the growth conditions and spanning the carbon doping concentration between ≤3 × 1015 cm−3 and 3 × 1019 cm−3. Using the optimized growth conditions that resulted in the lowest carbon incorporation, a vertical GaN SBD with a 6-μm drift layer was fabricated. A low turn-on voltage of 0.77 V with a breakdown voltage over 800 V was obtained from the device.
The structural properties of InGaN alloys and the interdependence on the thermoelectric behavior
Authors: Kucukgok Bahadir , Wu Xuewang , Wang Xiaojia , Liu Zhiqiang , Ferguson Ian T. , Lu Na
Published: February 2016

The III-Nitrides are promising candidate for high efficiency thermoelectric (TE) materials and devices due to their unique features which includes high thermal stability. A systematic study of the room temperature TE properties of metalorganic chemical vapor deposition grown InxGa1-xN were investigated for x =  0.07 to 0.24. This paper investigated the role of indium composition on the TE properties of InGaN alloys in particular the structural properties for homogenous material that did not show significant phase separation. The highest Seebeck and power factor values of 507 μV K−1 and 21.84 × 10−4 Wm−1K−1 were observed, respectively for In0.07Ga0.93N at room temperature. The highest value of figure-of-merit (ZT) was calculated to be 0.072 for In0.20Ga0.80N alloy at room temperature.
Solvothermal Synthesis of Single-Crystal Magnetite Hollow Sub-Microspheres: A Novel Formation Mechanism and Magnetic Properties
Authors: Yan Gongqin , Zhao Guanlin , He Fei
Published: February 2016

In this paper, single-crystal magnetite hollow sub-microspheres with a narrow diameter distribution are synthesized through a simple solvothermal process in ethylene glycol in the presence of urea and a small amount of water. The determining role of water in the solvothermal synthesis is studied. It is found that a small amount of water is crucial for the formation of the magnetite hollow spheres. A novel formation mechanism of the magnetite hollow spheres is proposed based on the bubble-assisted Ostwald ripening. It is believed that the appropriate amount of CO2 gas bubbles produced in situ by urea hydrolysis is crucial for the formation of hollow spheres. Because of the existence of gas microbubbles, magnetite solid spheres with a loose core and compact shell form, which is the key factor for the following inside-out Ostwald ripening and the formation of the hollow spheres. Thus, by simple changing of the water dosage, magnetite hollow spheres with different diameters and shell thicknesses are obtained controllably. The magnetic properties of the obtained magnetite hollow spheres are studied. It is found that the saturation magnetization of the magnetite hollow sub-microspheres decreases with the increasing shell thickness, whereas the coercivity and remanent magnetization increase with increasing shell thickness.
Diketopyrrolopyrrole-Based Low-Bandgap Conjugated Polymers with Siloxane Side Chains for Electrochromic Applications
Authors: Shi Zugui , Neo Wei Teng , Zhou Hui , Xu Jianwei
Published: February 2016

A series of conjugated copolymers P1–P3 were synthesized from 3,6-bis(5-bromothiophen-2-yl)-2,5-bis(6-(1,1,1,3,5,5,5-heptamethyltrisiloxan-3-yl)hexyl)-2,5-dihydropyrrolo[3,4-c]pyrrole-1,4-dione and 2,5-bis(trimethylstannyl)-3,4-dialkoxythiophene or its analogue via Stille coupling reactions, with molecular weights in the range of 13000–18000 g mol–1 and polydispersity indexes of 1.4–1.7. This new type of donor–acceptor polymers demonstrated reasonable switching speed, promising redox stability, together with high optical contrast and coloration efficiency. Although, at the current stage, the hybrid siloxane-terminated side chain did not significantly improve the overall performance of the resultant polymers, the unique chemical properties of the siloxane group would offer possibilities for crosslink after suitable post-polymerization treatment, and thus pave the way for future fine-tuning of the morphology of electrochromic films.
Limits to the precision of gradient sensing with spatial communication and temporal integration
Authors: Mugler Andrew , Levchenko Andre , Nemenman Ilya
Published: February 2016

Significance

Knowing which way to move is crucial for many biological processes, from organismal development to migration of cancer cells and from motion of microbes to wound healing. To find their preferred directions, biological systems compare concentrations of a chemical cue at their different edges. The comparison requires information from these different locations to be communicated to the same place. However, all communication is noisy (just think of the childhood game “telephone”). This communication noise, as well as noise in the individual measurements themselves, sets the accuracy of the direction sensing. Here we quantify the importance of the communication noise and propose a mechanism that can improve the accuracy of direction sensing.
Mobile small RNAs regulate genome-wide DNA methylation
Authors: Lewsey Mathew G. , Hardcastle Thomas J. , Melnyk Charles W. , Molnar Attila , Valli Adrián , Urich Mark A. , Nery Joseph R. , Baulcombe David C. , Ecker Joseph R.
Published: February 2016

Significance

Small RNAs (sRNAs) of 24 nt are associated with transcriptional gene silencing by targeting DNA methylation to complementary sequences. We demonstrated previously that sRNAs move from shoot to root, where they regulate DNA methylation of three endogenous transposable elements (TEs). However, the full extent of root DNA methylation dependent on mobile sRNAs was unknown. We demonstrate that DNA methylation at thousands of sites depends upon mobile sRNAs. These sites are associated with TE superfamilies found in gene-rich regions of the genome, which lose methylation selectively in an sRNA-deficient mutant. If the TEs were able to reactivate, they could cause genome instability and altered gene expression patterns, with negative effects on the plant. Consequently, mobile sRNAs may defend against these TEs.
When Human Immunodeficiency Virus (HIV) Treatment Goals Conflict with Guideline-Based Opioid Prescribing: A Qualitative Study of Hiv Treatment Providers
Authors: Starrels Joanna L. , Peyser Deena , Haughton Lorlette , Fox Aaron , Merlin Jessica S. , Arnsten Julia H. , Cunningham Chinazo O.
Published: February 2016

Background

Human immunodeficiency virus (HIV)-infected patients have a high prevalence of chronic pain and opioid use, making HIV care a critical setting for improving the safety of opioid prescribing. Little is known about HIV treatment providers’ perspectives about opioid prescribing to patients with chronic pain.

Methods

The authors administered a questionnaire and conducted semistructured telephone interviews with 18 HIV treatment providers (infectious disease specialists, general internists, family medicine physicians, nurse practitioners, and physician assistants) in Bronx, NY. Open-ended interview questions focused on providers’ experiences, beliefs, and attitudes about opioid prescribing and about the use of guideline-based opioid prescribing practices (conservative prescribing, and monitoring for and responding to misuse). Transcripts were thematically analyzed using a modified grounded theory approach.

Results

Eighteen HIV treatment providers included 13 physicians, four nurse practitioners, and one physician assistant. They were 62% female, 56% white, and practiced as HIV treatment providers for a mean of 14.6 years. Most reported always or almost always using opioid treatment agreements (56%) and urine drug testing (61%) with their patients on long-term opioid therapy. HIV treatment providers tended to view opioid prescribing for chronic pain within the “HIV paradigm,” a set of priorities and principles defined by three key themes: (1) primacy of HIV goals, (2) familiarity with substance use, and (3) the clinician as ally. The HIV paradigm sometimes supported, and sometimes conflicted with, guideline-based opioid prescribing practices. For HIV treatment providers, perceived alignment with the HIV paradigm determined whether and how guideline-based opioid prescribing practices were adopted. For example, the primacy of HIV goals superseded conservative opioid prescribing when providers prescribed opioids with the goal of retaining patients in HIV care. Conclusion: These findings highlight unique factors in HIV care that influence adoption of guideline-based opioid prescribing practices. These factors should be considered in future research and initiatives to address opioid prescribing in HIV care.
Measurement of gauge blocks by interferometry
Authors: Matus M , Haas S , Piree H , Gavalyugov V , Tamakyarska D , Thalmann R , Balling P , Garnaes J , Hald J , Farid N , Prieto E , Lassila A , Salgado J A , Lewis A , Bandis C , Mudronja V , Banreti E , Balsamo A , Pedone P , Bergmans R H , Karlsson H , Ramotowski Z , Eusebio L , Saraiva F , Duta A , Zelenika S , Bergstrand S , Fira R , Yandayan T , Sendogdu D , Ganioglu O , Akgoz S Asli , Franke P
Published: February 2016

The key comparison EURAMET.L-K1.2011 on gauge blocks was carried out in the framework of a EURAMET project starting in 2012 and ending in 2015. It involved the participation of 24 National Metrology Institutes from Europe and Egypt, respectively.

38 gauge blocks of steel and ceramic with nominal central lengths between 0.5 mm and 500 mm were circulated. The comparison was conducted in two loops with two sets of artifacts. A statistical technique for linking the reference values was applied. As a consequence the reference value of one loop is influenced by the measurements of the other loop although they did not even see the artifacts of the others. This influence comes solely from three "linking laboratories" which measure both sets of artifacts.

In total there were 44 results were not fully consistent with the reference values. This represents 10% of the full set of 420 results which is a considerable high number. At least 12 of them are clearly outliers where the participants have been informed by the pilot as soon as possible.

The comparison results help to support the calibration and measurement capabilities (CMCs) of the laboratories involved in the CIPM MRA.

Main text

To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.

The final report has been peer-reviewed and approved for publication by the CCL, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).
All-Si valley-Hall photonic topological insulator
Authors: Ma Tzuhsuan , Shvets Gennady
Published: February 2016

An all-Si photonic structure emulating the quantum-valley-Hall effect is proposed. We show that it acts as a photonic topological insulator (PTI), and that an interface between two such PTIs can support edge states that are free from scattering. The conservation of the valley degree of freedom enables efficient in- and out-coupling of light between the free space and the photonic structure. The topological protection of the edge waves can be utilized for designing arrays of resonant time-delay photonic cavities that do not suffer from reflections and cross-talk.
Gastroduodenal Perforation and Ulcer Associated With Rotavirus and Norovirus Infections in Japanese Children: A Case Report and Comprehensive Literature Review
Authors: Ueda Norishi
Published: February 2016

Background.  There is no literature review on gastroduodenal perforation or ulcer (GDPU) with rotavirus (RV) and norovirus (NoV) gastroenteritis.

Methods.  Pediatric cases of GDPU or upper gastrointestinal bleeding with RV and NoV gastroenteritis were searched from September 1974 until October 2015 using PubMed, Google for English, other-language-publications, and Ichushi (http://www.jamas.or.jp) for Japanese-language publications. All reports confirming GDPU or upper gastrointestinal bleeding with RV and NoV gastroenteritis were eligible for inclusion in the study. In addition, clinical characteristics were reviewed.

Results.  A boy with duodenal ulcer (DU) and NoV gastroenteritis was described. There were 32 GDPU cases (23 RVs and 9 NoVs cases), including our case; with the exception of 1 case, all were Japanese. Mean age, male/female ratio, and symptoms' duration before admission were 21.6 months, 2.2, and 4.0 days, respectively. Vomiting was the most common symptom, followed by diarrhea, lethargy, fever, abdominal distension, and convulsion. Dehydration, hematemesis, melena, drowsiness or unconsciousness, shock, metabolic acidosis, leukocytosis, anemia, positive C-reactive protein, high blood urea nitrogen, and hyponatremia commonly occurred. Helicobacter pylori was a minor cause of GDPU. Duodenal (DP) or gastric perforation (GP) developed in 14 cases (10 DP/RVs, 1 GP/RV, and 3 DP/NoVs). Duodenal ulcer or gastric ulcer (GU) developed in 18 cases (10 DU/RVs, 4 DU/NoVs, 1 GU/RV, 1 GU + DU/NoV, and 2 upper gastrointestinal bleeding/RVs). The predominant perforation or ulcer site was in the duodenum. With the exception of 2 deaths from DU, all cases recovered.

Conclusions.  Race, young age, male, severe dehydration, metabolic acidosis, drowsiness and unconsciousness, and shock may be potential risk factors of GDPU associated with RV and NoV gastroenteritis. Limitation of this descriptive study warrants further investigations to determine the risk factors in these infections that could be associated with GDPU.
Asymmetric Dimethylarginine in Adult Falciparum Malaria: Relationships With Disease Severity, Antimalarial Treatment, Hemolysis, and Inflammation
Authors: Barber Bridget E. , William Timothy , Grigg Matthew J. , Parameswaran Uma , Piera Kim A. , Yeo Tsin W. , Anstey Nicholas M.
Published: February 2016

Background.  Endothelial nitric oxide (NO) bioavailability is impaired in severe falciparum malaria (SM). Asymmetric dimethylarginine (ADMA), an endogenous inhibitor of NO synthase (NOS), contributes to endothelial dysfunction and is associated with mortality in adults with falciparum malaria. However, factors associated with ADMA in malaria, including the NOS-substrate l-arginine, hemolysis, and antimalarial treatment, are not well understood.

Methods.  In a prospective observational study of Malaysian adults with SM (N = 22) and non-SM (NSM; N = 124) and healthy controls (HCs), we investigated factors associated with plasma ADMA including the effects of antimalarial treatment.

Results.  Compared with HCs, ADMA levels were lower in NSM (0.488 µM vs 0.540 µM, P = .001) and in the subset of SM patients enrolled before commencing treatment (0.453 µM [N = 5], P = .068), but levels were higher in SM patients enrolled after commencing antimalarial treatment (0.610 µM [N = 17], P = .026). In SM and NSM, ADMA levels increased significantly to above-baseline levels by day 3. Baseline ADMA was correlated with arginine and cell-free hemoglobin in SM and NSM and inversely correlated with interleukin-10 in NSM. Arginine and the arginine/ADMA ratio (reflective of arginine bioavailability) were lower in SM and NSM compared with HCs, and the arginine/ADMA ratio was lower in SM compared with NSM.

Conclusions.  Pretreatment ADMA concentrations and l-arginine bioavailability are reduced in SM and NSM. Asymmetric dimethylarginine increases to above-baseline levels after commencement of antimalarial treatment. Arginine, hemolysis, and posttreatment inflammation all likely contribute to ADMA regulation, with ADMA likely contributing to the reduced NO bioavailability in SM.
Overexpression of the CYP51A1 Gene and Repeated Elements are Associated with Differential Sensitivity to DMI Fungicides in Venturia inaequalis
Authors: Villani Sara M. , Hulvey Jon , Hily Jean-Michel , Cox Kerik D.
Published: February 2016

The involvement of overexpression of the CYP51A1 gene in Venturia inaequalis was investigated for isolates exhibiting differential sensitivity to the triazole demethylation inhibitor (DMI) fungicides myclobutanil and difenoconazole. Relative expression (RE) of the CYP51A1 gene was significantly greater (P < 0.0001) for isolates with resistance to both fungicides (MRDR phenotype) or with resistance to difenoconazole only (MSDR phenotype) compared with isolates that were resistant only to myclobutanil (MRDS phenotype) or sensitive to both fungicides (MSDS phenotype). An average of 9- and 13-fold increases in CYP51A1 RE were observed in isolates resistant to difenoconazole compared with isolates with MRDS and MSDS phenotypes, respectively. Linear regression analysis between isolate relative growth on myclobutanil-amended medium and log10 RE revealed that little to no variability in sensitivity to myclobutanil could be explained by CYP51A1 overexpression (R2 = 0.078). To investigate CYP51A1 upstream anomalies associated with CYP51A1 overexpression or resistance to difenoconazole, Illumina sequencing was conducted for three isolates with resistance to difenoconazole and one baseline isolate. A repeated element, “EL 3,1,2”, with the properties of a transcriptional enhancer was identified two to four times upstream of CYP51A1 in difenoconazole-resistant isolates but was not found in isolates with the MRDS phenotype. These results suggest that different mechanisms may govern resistance to different DMI fungicides in the triazole group.
Inhibition of p21-Activated Kinase 1 by IPA-3 Promotes Locomotor Recovery After Spinal Cord Injury in Mice
Authors: Ji Xinran , Zhang Yiling , Zhang Lihai , Chen Hua , Peng Ye , Tang Peifu
Published: February 2016

Study Design.

Ninety-six male adult CD-1 mice were randomly divided into sham, spinal cord injury (SCI) + vehicle, and SCI + IPA-3 groups. Expression of matrix metalloproteinase (MMP)-2 and MMP-9, production of tumor necrosis factors (TNF)-α and interleukin (IL)-1β, tissue edema, blood-spinal cord barrier penetrability, neural cell apoptosis, and neurological function recovery were measured.

Objective.

The aim of the study was to evaluate the effect of specific inhibition of p21-activated kinase 1 (PAK1) by IPA-3 on SCI and the underlying mechanisms thereof.

Summary of Background Data.

SCI is a devastating clinical condition that may result in long-lasting and deteriorating functional deficits. The major goal of SCI treatment is to limit the development of secondary injury. IPA-3, a PAK1 inhibitor, exhibited neuroprotection against secondary damage after traumatic brain injury and subarachnoid hemorrhage (SAH).

Methods.

MMP-2, MMP-9, and cleaved caspase-3 expression were assessed by Western blot. Inflammatory cytokines TNF-α and IL-1β were detected by enzyme-linked immunosorbent assay (ELISA). The blood-spinal cord barrier disruption was measured by water content and Evans blue extravasation of the spinal cord. Neuronal apoptosis was evaluated by Nissl staining and Terminal-deoxynucleoitidyl Transferase Mediated Nick End Labeling (TUNEL) assay. The locomotor behavior of hind limb was evaluated by Basso Mouse Scale (BMS) at 1, 3, 7, 14, and 28 days post-injury.

Results.

Compared with SCI + vehicle mice, IPA-3 treatment showed decreased p-PAK1, MMP-2, MMP-9, cleaved caspase-3, TNF-α, and IL-1β expression. Moreover, inhibition of PAK1 by IPA-3 reduced spinal cord water content and Evans blue extravasation, increased neuronal survival, and reduced TUNEL-positive cells at 24 hours after SCI. Furthermore, IPA-3 improved spinal cord functional recovery 7 days after SCI.

Conclusion.

Inhibition of PAK1 by IPA-3 promoted recovery of neurological function, possibly by downregulating the expression of MMP-2, MMP-9, TNF-α, and IL-1β. Our data suggest that PAK1 may be a potential therapeutic target in patients with SCI.

Level of Evidence: 1
Local Epiphyseal Growth Modulation for the Early Treatment of Progressive Scoliosis
Authors: Hachem Bahe , Aubin Carl-Eric , Parent Stefan
Published: February 2016

Study Design.

Experimental study of a localized device for the control of the vertebral growth using an immature porcine model.

Objective.

The aim of the study was to experimentally evaluate a localized device acting on the epiphyseal growth plates without bridging the intervertebral disc of immature hybrid pigs over 3 months of growth.

Summary of Background Data.

Based on current published literature, fusionless devices offer promising scoliosis treatment alternatives to conventional spinal instrumentation and fusion in the growing spine. Current compression-based devices achieve growth modulation while also compressing the intervertebral discs, increasing the risk of long-term disc degeneration.

Methods.

An intravertebral staple acting on both the superior and inferior growth plates was inserted locally over T7–T9 of seven healthy immature pigs. Four age-matched animals served as controls. Radiographs were acquired monthly to assess induced spinal curvature and vertebral wedging (inverse model). Global (spinal) and local (vertebral, discal) geometric changes were evaluated over 3-months follow-up. Final left/right vertebral height differences were also quantified.

Results.

The only postoperative complication observed was one pig that had a persistent deep infection and was excluded from the study. No significant changes in spinal alignment were reported in control animals. Final induced Cobb angle was 25.0° ± 4.2° measured over T7–T9, with no observable sagittal profile modification. Highest vertebral wedging occurred at T9 with 18.2° ± 2.7°. Cumulative vertebral wedging over T7–T9 accounted for 45.4°, demonstrating evidence of reversed disc wedge phenomenon. Vertebral height was 3.9 ± 1.0 mm shorter on the instrumented side suggesting full growth restraint. Local and regional induced deformities significantly differed from their control counterparts (P < 0.001).

Conclusion.

In this animal model, the local epiphyseal device achieved significant localized growth modulation over as little as three instrumented levels, with explicit vertebral wedging exclusive of the intervertebral disc. By increasing the number of instrumented levels, one may achieve higher curvature control potentially providing a unique local correction method to correct spinal deformity without affecting the intervertebral disc.

Level of Evidence: 5
Tacrolimus Predose Concentration Is Associated With Hypertension in Pediatric Liver Transplant Recipients
Authors: Prytula Agnieszka , Vandekerckhove Kristof , Raes Ann , De Wolf Daniel , Dehoorne Jo , Vande Walle Johan , De Bruyne Ruth
Published: February 2016

Background:

The aim of the study was to analyze the incidence of hypertension in pediatric liver transplantation (LT) recipients using ambulatory blood pressure measurements (ABPM) and to identify factors associated with hypertension. We also investigated whether hypertension or tacrolimus predose concentration (TAC C0) was associated with increased left ventricular (LV) wall thickness.

Patients and Methods:

On a retrospective longitudinal base, we included 39 pediatric LT recipients. Median time since transplantation was 65 months (range: 11–183). Two consecutive ABPM were analyzed with a median time interval of 13 months. Data from echocardiographic evaluation parallel to the baseline ABPM were analyzed. All patients except 1 were prescribed tacrolimus. The median TAC C0 was 4 ng/mL (range 0.9–11.2). Univariate and multivariate logistic regression models were fitted to identify factors associated with systolic and diastolic hypertension and LV wall thickness.

Results:

Twenty‐two of 39 children were hypertensive at baseline and 19 of 32 were hypertensive at follow‐up. At baseline 10 (26%) children had masked systolic hypertension. TAC C0 was associated with systolic (P = 0.007, Exp(B) 2.02, 95% CI 1.2–3.3) and diastolic (P = 0.044, Exp(B) 1.48, 95% CI 1.0–2.2) hypertension. LV wall thickness was increased in children after LT compared with healthy population, but it was not associated with hypertension or TAC C0.

Conclusions:

Given the high prevalence of masked hypertension, ABPM should be performed in all pediatric LT recipients. Systolic and diastolic hypertension is associated with TAC C0; therefore, children with a higher target TAC C0 require a more intensive blood pressure surveillance.
Effect of Vitamin E With Therapeutic Iron Supplementation on Iron Repletion and Gut Microbiome in US Iron Deficient Infants and Toddlers
Authors: Tang Minghua , Frank Daniel N. , Sherlock Laurie , Ir Diana , Robertson Charles E. , Krebs Nancy F.
Published: February 2016

Background:

Iron therapy induces inflammation, which could decrease iron absorption. Increased exposure of iron in the gut could also alter microbiome file. Providing antioxidants such as vitamin E with iron therapy has been associated with reduced oxidative potential.

Objective:

The aim of the present study was to test the efficacy of adding vitamin E to therapeutic iron therapy on iron repletion, inflammation markers, and gut microbiome in iron‐deficient infants and toddlers.

Design:

This was a randomized, double‐blind, control trial in which infants and toddlers (Denver, CO metro area) who were at risk of iron deficiency were screened. Eligible participants were randomized to receive iron therapy (6 mg · kg−1 · day−1) plus placebo (n = 22) or iron (6 mg · kg−1 · day−1) and vitamin E (18 mg/day, n = 14) for 8 weeks. Iron and inflammation status, and gut microbiome (16S sequencing) were analyzed in all participants before and after the treatment.

Results:

After 8 weeks of treatment, average serum ferritin level returned to normal for both iron + placebo and iron + vitamin E groups at 33.3 ± 20.2 and 33.5 ± 21.5 μg/L, respectively. Serum vitamin E concentration increased in iron + vitamin E group. No change over time was observed regarding serum interleukin‐4, tumor necrosis factor‐α, or fecal calprotectin. The relative abundance of the genus Roseburia (phylum Firmicutes), a butyrate producer, increased in the Fe + E group (Δ1.3%, P < 0.01). Also at the genus level, the genus Escherichia decreased by 1.2% on average among all participants (effect of time P = 0.01).

Conclusions:

Using a therapeutic iron dose of 6 mg · kg−1 · day−1 is effective in treating iron deficiency during an 8‐week period, without inducing persistent inflammatory response. Changes of the gut microbiome raised the possibility that antioxidant therapy in conjunction with therapeutic iron supplementation could potentially improve microbial community profiles in the intestinal tract.
Functionally relevant responses to human facial expressions of emotion in the domestic horse (
Equus caballus
)
Authors: Smith Amy Victoria , Proops Leanne , Grounds Kate , Wathan Jennifer , McComb Karen
Published: February 2016

Whether non-human animals can recognize human signals, including emotions, has both scientific and applied importance, and is particularly relevant for domesticated species. This study presents the first evidence of horses' abilities to spontaneously discriminate between positive (happy) and negative (angry) human facial expressions in photographs. Our results showed that the angry faces induced responses indicative of a functional understanding of the stimuli: horses displayed a left-gaze bias (a lateralization generally associated with stimuli perceived as negative) and a quicker increase in heart rate (HR) towards these photographs. Such lateralized responses towards human emotion have previously only been documented in dogs, and effects of facial expressions on HR have not been shown in any heterospecific studies. Alongside the insights that these findings provide into interspecific communication, they raise interesting questions about the generality and adaptiveness of emotional expression and perception across species.
Thermodynamics and kinetics of the FoF1-ATPase: application of the probability isotherm
Authors: Chapman Brian , Loiselle Denis
Published: February 2016

We use the results of recent publications as vehicles with which to discuss the thermodynamics of the proton-driven mitochondrial FoF1-ATP synthase, focusing particularly on the possibility that there may be dissociation between rotatory steps and ATP synthesis/hydrolysis. Such stoichiometric ‘slippage’ has been invoked in the literature to explain observed non-ideal behaviour. Numerical solution of the Rate Isotherm (the kinetic equivalent of the more fundamental Probability Isotherm) suggests that such ‘slippage’ is an unlikely explanation; instead, we suggest that the experimental results may be more consistent with damage to the enzyme caused by its isolation from the biomembrane and its experimental fixation, resulting in non-physiological friction within the enzyme's rotary mechanism. We emphasize the unavoidable constraint of the Second Law as instantiated by the obligatory dissipation of Gibbs Free Energy if the synthase is to operate at anything other than thermodynamic equilibrium. We use further numerical solution of the Rate Isotherm to demonstrate that there is no necessary association of low thermodynamic efficiency with high metabolic rates in a bio-world in which the dominating mechanism of metabolic control is multifactorial enzyme activation.
Simulated annealing approach to vascular structure with application to the coronary arteries
Authors: Keelan Jonathan , Chung Emma M. L. , Hague James P.
Published: February 2016

Do the complex processes of angiogenesis during organism development ultimately lead to a near optimal coronary vasculature in the organs of adult mammals? We examine this hypothesis using a powerful and universal method, built on physical and physiological principles, for the determination of globally energetically optimal arterial trees. The method is based on simulated annealing, and can be used to examine arteries in hollow organs with arbitrary tissue geometries. We demonstrate that the approach can generate in silico vasculatures which closely match porcine anatomical data for the coronary arteries on all length scales, and that the optimized arterial trees improve systematically as computational time increases. The method presented here is general, and could in principle be used to examine the arteries of other organs. Potential applications include improvement of medical imaging analysis and the design of vascular trees for artificial organs.
A highly infective plant-associated bacterium influences reproductive rates in pea aphids
Authors: Hendry Tory A. , Clark Kelley J. , Baltrus David A.
Published: February 2016

Pea aphids,Acyrthosiphon pisum, have the potential to increase reproduction as a defence against pathogens, though how frequently this occurs or how infection with live pathogens influences this response is not well understood. Here we determine the minimum infective dose of an environmentally common bacterium and possible aphid pathogen,Pseudomonas syringae, to determine the likelihood of pathogenic effects to pea aphids. Additionally, we usedP. syringaeinfection to investigate how live pathogens may alter reproductive rates. We found that oral bacterial exposure decreased subsequent survival of aphids in a dose-dependent manner and we estimate that ingestion of less than 10 bacterial cells is sufficient to increase aphid mortality. Pathogen dose was positively related to aphid reproduction. Aphids exposed to low bacterial doses showed decreased, although statistically indistinguishable, fecundity compared to controls. Aphids exposed to high doses reproduced significantly more than low dose treatments and also more, but not significantly so, than controls. These results are consistent with previous studies suggesting that pea aphids may use fecundity compensation as a response to pathogens. Consequently, even low levels of exposure to a common plant-associated bacterium may therefore have significant effects on pea aphid survival and reproduction.
A computational approach to studying ageing at the individual level
Authors: Harvanek Zachary M. , Mourão Márcio A. , Schnell Santiago , Pletcher Scott D.
Published: February 2016

The ageing process is actively regulated throughout an organism's life, but studying the rate of ageing in individuals is difficult with conventional methods. Consequently, ageing studies typically make biological inference based on population mortality rates, which often do not accurately reflect the probabilities of death at the individual level. To study the relationship between individual and population mortality rates, we integrated
in vivo
switch experiments with
in silico
stochastic simulations to elucidate how carefully designed experiments allow key aspects of individual ageing to be deduced from group mortality measurements. As our case study, we used the recent report demonstrating that pheromones of the opposite sex decrease lifespan in
Drosophila melanogaster
by reversibly increasing population mortality rates. We showed that the population mortality reversal following pheromone removal was almost surely occurring in individuals, albeit more slowly than suggested by population measures. Furthermore, heterogeneity among individuals due to the inherent stochasticity of behavioural interactions skewed population mortality rates in middle-age away from the individual-level trajectories of which they are comprised. This article exemplifies how computational models function as important predictive tools for designing wet-laboratory experiments to use population mortality rates to understand how genetic and environmental manipulations affect ageing in the individual.