bluuebunny/crossref_metadata_2025 huggingface dataset:
Mechanical Behaviors of Rice Husk and Boiled Egg Shell Particles Impregnated Coir‐Polyester Composites
Authors: Bharathiraja G. , Jayabal S. , Kalyana Sundaram S. , Rajamuneeswaran S. , Manjunath B. H.
Published: March 2016

This paper aims at improving the mechanical properties of coir fiber reinforced polyester composites through impregnation of rice husk and boiled egg shell in polyester matrix. The composites sheets were manufactured by varying the fabrication parameters such as fiber length, particulate content and fiber content. The mechanical properties of the fabricated composites were determined as per ASTM standards and the effects of fiber length, particulate content and fiber content on mechanical properties of rice husk and boiled egg shells impregnated coir ‐ polyester composites were studied. Scanning electron microscope analysis was used to characterize the fracture behavior of the composites. The investigation witnessed the improvement in mechanical properties on addition of rice husk particulate in coir fiber reinforced polyester composites. Similarly the addition of boiled egg shell in to the composites has enhanced mouldability of the composites. The SEM investigation evidenced the arrest of crack propagation and voids formation on addition of rice husk and egg shell particulates in polyester matrix. This study confirmed the possibility of using rice husk and boiled egg shell impregnated coir fiber reinforced polyester composites in low load bearing applications.
Characterization of Terephthalic Acid Monomer Recycled from Post‐Consumer PET Polymer Bottles
Authors: Ravichandran Sankaranarayanan Ayyakudi , Rajan Vignesh Peranamallur , Aravind Pritham Velamur , Seenivasan A. , Prakash D. Gnana , Ramakrishnan K.
Published: March 2016

The idea of recycling of PET to obtain terephthalic acid (TPH) monomer is fast gaining traction; therefore it has become imperative to develop standard characterization methods to assess the purity of terephthalic acid using reliable and easily available laboratory equipment/techniques. Experimental studies on recycling of post‐consumer PET waste were conducted in a batch reactor. The PET was subjected to a de‐esterification reaction to break down the ester bonds via alkali decomposition in ethylene glycol at 155 °C under the influence of ultrasound. The end product, terephthalic acid, was characterized for the functional purity using UV‐Visible spectrophotometry, FT‐IR, and thermal methods. The terephthalic acid was ascertained by the characteristic peak at 240 nm using UV‐Visible spectrophotometer and was quantified using a commercially available standard sample of terephthalic acid. The purity of end product was confirmed using FT‐IR and thermogravimetric and differential thermal analysis.
Styrene‐Butadiene Rubber/Modified Ground Tire Rubber Blends Co‐Vulcanization: Effect of Accelerator Type
Authors: Formela Krzysztof , Formela Magdalena , Thomas Sabu , Haponiuk Józef
Published: March 2016

Ground tire rubber was thermo‐mechanically modified with using a co‐rotating twin screw extruder. Modification of GTR was conducted in autothermal conditions. Styrene‐butadiene rubber and modified ground tire rubber blends were prepared via two‐roll milling. Obtained compounds were cured with conventional system (sulfur/vulcanization accelerator ratio was 2:1). During this research three commonly vulcanization accelerators (MBT, TBBS, TMTD) were used. Curing characteristics, static mechanical properties (tensile strength, elongation at break, hardness, resilience), dynamic mechanical properties, swelling degree and thermal properties of obtained SBR/mGTR blends were determined. SBR/modified GTR blends with higher amount of modified GTR shown improvement in tensile strength, on the other hand vulcanization accelerator type had strong influence on curing parameters, tensile strength, elongation at break, swelling degree and glass transition temperature. The best curing and mechanical properties were estimated for SBR/mGTR blend with 50 phr mGTR cured with TMTD accelerator.
Motor and Nonmotor Features of Carriers of the p.A53T Alpha‐Synuclein Mutation: A Longitudinal Study
Authors: Papadimitriou Dimitra , Antonelou Roubina , Miligkos Michael , Maniati Matina , Papagiannakis Nikolaos , Bostantjopoulou Sevasti , Leonardos Athannassios , Koros Christos , Simitsi Athina , Papageorgiou Sokratis G. , Kapaki Elisabeth , Alcalay Roy N. , Papadimitriou Alexandros , Athanassiadou Aglaia , Stamelou Maria , Stefanis Leonidas
Published: March 2016

Background

G209A SNCA mutation carriers represent an important group of genetic PD. We describe motor and nonmotor features of G209A SNCA mutation carriers.

Methods

Longitudinal clinical assessments over 2 years were collected in 22 symptomatic and 8 asymptomatic G209A SNCA mutation carriers. Motor and nonmotor rating scales were administered. Correlations were performed between clinical variables and disease duration or age. Penetrance was calculated using Kaplan‐Meier survival curves.

Results

Asymptomatic carriers did not manifest clear premotor symptoms, but symptomatic carriers often reported that olfactory dysfunction and rapid eye movement sleep behavior disorder preceded motor symptoms. Prominent motor decline and deterioration of autonomic and cognitive function occurred at follow‐up; such nonmotor features correlated with disease duration, but not age. Disease penetrance was estimated at around 90%.

Conclusions

This study may help to inform clinical trials and provide the basis for studies of disease modifiers in genetic synucleinopathy cohorts. © 2016 International Parkinson and Movement Disorder Society
Advances in Activity Cliff Research
Authors: Dimova Dilyana , Bajorath Jürgen
Published: March 2016

Activity cliffs, i.e. similar compounds with large potency differences, are of interest from a chemical and informatics viewpoint; as a source of structure‐activity relationship information, for compound optimization, and activity prediction. Herein, recent highlights of activity cliff research are discussed including studies that have further extended our understanding of activity cliffs, yielded unprecedented insights, or paved the way for practical applications.
Prevention of hormonal breast cancer by dietary jamun
Authors: Aqil Farrukh , Jeyabalan Jeyaprakash , Munagala Radha , Singh Inder Pal , Gupta Ramesh C.
Published: March 2016

Scope

Syzygium cumini (jamun) is perhaps the only berry that has the diversity of anthocyanidins of blueberry and bilberry and the abundance of ellagitannins/ellagic acid of black raspberry. Here, we report the potential of jamun against 17β‐estrogen‐mediated breast cancer and the role of miRNAs and other targets in disease inhibition.

Methods and results

Female August‐Copenhagen Irish rats were given AIN‐93M diet or diet supplemented with jamun. Two weeks later, animals received 17β‐estradiol and were palpated weekly for the mammary tumors. At the end of 26 weeks, the jamun‐diet significantly delayed the first tumor appearance by 21 days, and reduced the tumor incidence (65% versus 96%), tumor burden (313 ± 95 versus 661 ± 123 mm3) and tumor multiplicity (1.8 ± 0.3 versus 4.2 ± 0.4 tumors/rat) compared to control. The experimental diet significantly reduced the estrogen‐associated growth of pituitary prolactinomas, circulating prolactin and estradiol levels and offset estrogen‐associated increases in mammary cell‐proliferation, estrogen receptor‐alpha (ER‐α), and cyclinD1. miRNAs that were either overexpressed (miR‐182 and miR‐375) or underexpressed (miR‐127 and miR‐206) following estrogen‐treatment were significantly protected by jamun diet.

Conclusions

Together, our data show that jamun significantly offset estrogen‐mediated alterations in mammary cell‐proliferation, ER‐α, cyclinD1, and candidate miRNAs, and that the modulation of these biomarkers correlated with a reduction in mammary carcinogenicity.
A novel TRIM family member, Trim69, regulates zebrafish development through p53‐mediated apoptosis
Authors: Han Ruiqin , Zhao Qing , Zong Shudong , Miao Shiying , Song Wei , Wang Linfang
Published: March 2016

Trim69 contains the hallmark domains of a tripartite motif (TRIM) protein, including a Ring‐finger domain, B‐box domain, and coiled‐coil domain. Trim69 is structurally and evolutionarily conserved in zebrafish, mouse, rat, human, and chimpanzee. The role of this protein is unclear, however, so we investigated its function in zebrafish development. Trim69 is extensively expressed in zebrafish adults and developing embryos—particularly in the testis, brain, ovary, and heart—and its expression decreases in a time‐ and stage‐dependent manner. Loss of trim69 in zebrafish induces apoptosis and activates apoptosis‐related processes; indeed, the tp53 pathway was up‐regulated in response to the knockdown. Expression of human trim69 rescued the apoptotic phenotype, while overexpression of trim69 does not increase cellular apoptosis. Taken together, our results suggest that trim69 participates in tp53‐mediated apoptosis during zebrafish development. Mol. Reprod. Dev. 83: 442–454, 2016. © 2016 Wiley Periodicals, Inc.
ROUTE: run‐time robust reducer workload estimation for MapReduce
Authors: Liu Zhihong , Zhang Qi , Boutaba Raouf , Liu Yaping , Gong Zhenghu
Published: March 2016

MapReduce has become a popular model for large‐scale data processing in recent years. Many works on MapReduce scheduling (e.g., load balancing and deadline‐aware scheduling) have emphasized the importance of predicting workload received by individual reducers. However, because the input characteristics and user‐specified map function of a given job are unknown to the MapReduce framework before the job starts, accurately predicting workload of reducers can be a difficult challenge. To address this challenge, we present ROUTE, a run‐time robust reducer workload estimation technique for MapReduce. ROUTE progressively samples the partition size of the early completed mappers, allowing ROUTE to perform estimation at run time yet fulfilling the accuracy requirement specified by users. Moreover, by using robust estimation and bootstrapping resampling techniques, ROUTE can achieve high applicability to a wide variety of applications. Through experiments using both real and synthetic data on an 11‐node Hadoop cluster, we show ROUTE can achieve high accuracy with error rate no more than 10.92% and an improvement of 40.6% in terms of error rate while compared with the state‐of‐the‐art solution. Besides, through simulations using synthetic data, we show that ROUTE is robust to a variety of skewed distributions. Finally, we apply ROUTE to existing load balancing and deadline‐aware scheduling frameworks and show ROUTE significantly improves the performance of these frameworks. Copyright © 2016 John Wiley & Sons, Ltd.
Unhealthy eating behaviors and weight gain: A prospective study in young and middle‐age adults
Authors: León‐Muñoz Luz M. , García‐Esquinas Esther , Soler‐Vila Hosanna , Guallar‐Castillón Pilar , Banegas José R. , Rodríguez‐Artalejo Fernando
Published: March 2016

Objective

Guidelines for obesity prevention recommend reducing certain unhealthy eating behaviors (UEB). However, the association between UEB and weight gain is uncertain.

Methods

Prospective cohort with 1,638 individuals aged 18‐60 years was recruited in 2008‐2010. UEB assessed at baseline were: not planning how much to eat, consuming pre‐cooked/canned food, buying snacks, eating in fast‐food restaurants, not choosing low‐calorie foods, not removing visible fat from meat or skin from chicken, and eating while watching TV or seating on a sofa. Participants were followed up through 2012 to assess weight change.

Results

Compared to reporting 0‐2 UEB, the multivariate odds ratios (95% confidence interval) for gaining ≥3 kg were 0.97 (0.74‐1.28) for 3‐4 UEB and 1.61 (1.09‐2.39) for ≥5 UEB, P‐trend = 0.07. Results were similar for gaining ≥5 kg. The three UEB with the strongest associations with weight gain were: 1) not planning the amount of food to eat, 2) eating at fast‐food restaurants, and 3) eating while watching TV; compared to having none of these three behaviors, the odds ratio (95% confidence interval) for gaining ≥3 kg was 1.54 (0.77‐3.08) for 1 UEB, 1.70 (0.85‐3.37) for 2 UEB, and 2.75 (1.28‐5.90) for 3 UEB, P‐trend = 0.007. Similar results were obtained for gaining ≥5 kg.

Conclusions

Several UEB are associated with weight gain.
High‐fat diet exacerbates pain‐like behaviors and periarticular bone loss in mice with CFA‐induced knee arthritis
Authors: Loredo‐Pérez Aleyda A. , Montalvo‐Blanco Carlos E. , Hernández‐González Luis I. , Anaya‐Reyes Maricruz , Fernández del Valle‐Laisequilla Cecilia , Reyes‐García Juan G. , Acosta‐González Rosa I. , Martínez‐Martínez Arisai , Villarreal‐Salcido Jaira C. , Vargas‐Muñoz Virginia M. , Muñoz‐Islas Enriqueta , Ramírez‐Rosas Martha B. , Jiménez‐Andrade Juan M.
Published: March 2016

Objective

Our aim was to quantify nociceptive spontaneous behaviors, knee edema, proinflammatory cytokines, bone density, and microarchitecture in high‐fat diet (HFD)‐fed mice with unilateral knee arthritis.

Methods

ICR male mice were fed either standard diet (SD) or HFD starting at 3 weeks old. At 17 weeks, HFD and SD mice received intra‐articular injections either with Complete Freund's Adjuvant (CFA) or saline into the right knee joint every 7 days for 4 weeks. Spontaneous pain‐like behaviors and knee edema were assessed for 26 days. At day 26 post‐first CFA injection, serum levels of IL‐1β, IL‐6, and RANKL were measured by ELISA, and microcomputed tomography analysis of knee joints was performed.

Results

HFD‐fed mice injected with CFA showed greater spontaneous pain‐like behaviors of the affected extremity as well as a decrease in the weight‐bearing index compared to SD‐fed mice injected with CFA. Knee edema was not significantly different between diets. HFD significantly exacerbated arthritis‐induced bone loss at the distal femoral metaphysis but had no effect on femoral diaphyseal cortical bone. HFD did not modify serum levels of proinflammatory cytokines.

Conclusions

HFD exacerbates pain‐like behaviors and significantly increases the magnitude of periarticular trabecular bone loss in a murine model of unilateral arthritis.
Preparation of alginate hydrogels containing silver nanoparticles: a facile approach for antibacterial applications
Authors: Rescignano Nicoletta , Hernandez Rebeca , Lopez Lionel D , Calvillo Inmaculada , Kenny Josè M , Mijangos Carmen
Published: March 2016

Nowadays polymer nanocomposites represent an important stake in scientific research and offer a combination of properties with respect to single components. The present work deals with nanocomposite hydrogels obtained from alginate, a biobased polymer, which is employed as a biocompatible matrix for the encapsulation of silver nanoparticles (AgNPs). Alginate nanocomposite hydrogels were obtained through crosslinking with calcium carbonate (CaCO3) and d‐glucono‐δ‐lactone (GDL) at different AgNP concentrations. The effect of the encapsulation of AgNPs within alginate hydrogels on their porous structure and the AgNP dispersion was evaluated through field‐emission scanning electron microscopy. Oscillatory rheological measurements were carried out in order to determine the alginate/AgNP ratio suitable for achieving a higher elastic modulus. Finally, nanocomposite alginate hydrogels were found to be effective against Escherichia coli and Pseudomonas aeruginosa bacteria, with inhibition zones ranging between 5 and 7 cm after 24 h of incubation at 37 °C. Therefore, the present work proposes a nanocomposite alginate hydrogel for application as bactericidal materials in the biotechnology and biomedical fields. © 2016 Society of Chemical Industry
A strategy for absolute proteome quantification with mass spectrometry by hierarchical use of peptide‐concatenated standards
Authors: Kito Keiji , Okada Mitsuhiro , Ishibashi Yuko , Okada Satoshi , Ito Takashi
Published: March 2016

The accurate and precise absolute abundance of proteins can be determined using mass spectrometry by spiking the sample with stable isotope‐labeled standards. In this study, we developed a strategy of hierarchical use of peptide‐concatenated standards (PCSs) to quantify more proteins over a wider dynamic range. Multiple primary PCSs were used for quantification of many target proteins. Unique “ID‐tag peptides” were introduced into individual primary PCSs, allowing us to monitor the exact amounts of individual PCSs using a “secondary PCS” in which all “ID‐tag peptides” were concatenated. Furthermore, we varied the copy number of the “ID‐tag peptide” in each PCS according to a range of expression levels of target proteins. This strategy accomplished absolute quantification over a wider range than that of the measured ratios. The quantified abundance of budding yeast proteins showed a high reproducibility for replicate analyses and similar copy numbers per cell for ribosomal proteins, demonstrating the accuracy and precision of this strategy. A comparison with the absolute abundance of transcripts clearly indicated different post‐transcriptional regulation of expression for specific functional groups. Thus, the approach presented here is a faithful method for the absolute quantification of proteomes and provides insights into biological mechanisms, including the regulation of expressed protein abundance.
A New Method for Quantitative XEDS Tomography of Complex Heteronanostructures
Authors: Zanaga Daniele , Altantzis Thomas , Polavarapu Lakshminarayana , Liz‐Marzán Luis M. , Freitag Bert , Bals Sara
Published: March 2016

Reliable quantification of 3D results obtained by X‐ray energy‐dispersive spectroscopy (XEDS) tomography is currently hampered by the presence of shadowing effects and poor spatial resolution. Here, a method is presented which overcomes these problems by synergistically combining quantified XEDS data and high angle annular dark field–scanning transmission electron microscopy tomography. As a proof of principle, the approach is applied to characterize a complex Au/Ag nanorattle obtained through a galvanic replacement reaction. However, the technique that is proposed here is widely applicable to a broad range of nanostructures.
Conservation of structural fluctuations in homologous protein kinases and its implications on functional sites
Authors: Kalaivani Raju , de Brevern Alexandre G. , Srinivasan Narayanaswamy
Published: March 2016

Our aim is to explore the similarities in structural fluctuations of homologous kinases. Gaussian Network Model based Normal Mode Analysis was performed on 73 active conformation structures in Ser/Thr/Tyr kinase superfamily. Categories of kinases with progressive evolutionary divergence, viz. (i) Same kinase with many crystal structures, (ii) Within‐Subfamily, (iii) Within‐Family, (iv) Within‐Group, and (v) Across‐Group, were analyzed. We identified a flexibility signature conserved in all kinases involving residues in and around the catalytic loop with consistent low‐magnitude fluctuations. However, the overall structural fluctuation profiles are conserved better in closely related kinases (Within‐Subfamily and Within‐family) than in distant ones (Within‐Group and Across‐Group). A substantial 65.4% of variation in flexibility was not accounted by variation in sequences or structures. Interestingly, we identified substructural residue‐wise fluctuation patterns characteristic of kinases of different categories. Specifically, we recognized statistically significant fluctuations unique to families of protein kinase A, cyclin‐dependent kinases, and nonreceptor tyrosine kinases. These fluctuation signatures localized to sites known to participate in protein‐protein interactions typical of these kinase families. We report for the first time that residues characterized by fluctuations unique to the group/family are involved in interactions specific to the group/family. As highlighted for Src family, local regions with differential fluctuations are proposed as attractive targets for drug design. Overall, our study underscores the importance of consideration of fluctuations, over and above sequence and structural features, in understanding the roles of sites characteristic of kinases. Proteins 2016; 84:957–978. © 2016 Wiley Periodicals, Inc.
DLTS analysis of high resistive edge termination technique‐induced defects in GaN‐based Schottky barrier diodes
Authors: Koné Sodjan , Cayrel Frederic , Yvon Arnaud , Collard Emmanuel , Alquier Daniel
Published: March 2016

Efficient edge terminations are fundamental for power electronic devices. High resistive edge termination technique obtained by ion implantation is a possible solution for GaN Schottky barrier diodes (SBD), but may induce defects detrimental to the devices. In this work, two sets of GaN SBDs, with or without a high resistive guard ring edge termination, were investigated by deep levels transient spectroscopy (DLTS). The corresponding DLTS spectra of devices with guard ring were compared to those of as‐fabricated devices (without). Four deep traps at 0.13, 0.26, 0.35, and 0.51 eV were observed below the conduction band in as‐fabricated structures while the ones with guard ring exhibit two additional levels at 0.47 and 0.80 eV and a strong enhancement in DLTS peaks magnitude. Further investigations showed that the additional traps detected in SBD devices with guard ring were consistent with ion implantation‐induced damages. These observations highlight the impact of high resistive edge termination technique on our devices and raise the need of optimization of such crucial structure for the improvement of GaN‐based Schottky barrier diode.
Prototyping of nanophotonic grating back contacts for light trapping in planar silicon solar cells
Authors: Smeets Michael , Lentz Florian , Richter Alexei , Augarten Yael , Bittkau Karsten , Ding Kaining , Carius Reinhard , Rau Uwe , Paetzold Ulrich W.
Published: March 2016

Nanophotonic gratings can be used for efficient light trapping in crystalline silicon solar cells. A common challenge is the high quality surface passivation, when applying such gratings. In this article, we report on the prototyping of the application of nanophotonic grating back contacts to planar silicon heterojunction solar cells for improved light trapping. These back contacts are processed after the Si wafer passivation, omitting any direct texturing of the absorber layer. Thereby, maintaining the integrity of the planar passivation layer of high quality and simultaneous light trapping is realized. The induced light‐trapping effect is further studied by photoluminescence imaging, external quantum efficiency measurements as well as absorptance measurements of solar cells applying nanophotonic grating back contacts of different grating periods. A clear correlation is found for the three characterization methods which allows the optimal period for efficient light trapping in the investigated solar cells to be identified. For the optimized grating period of the nanophotonic grating back contact an increased short‐circuit current density is obtained and the power conversion efficiency is enhanced by 0.4%, absolute.
Alteration of the structure and surface composition of crystalline‐amorphous porous clay heterostructures upon iron doping from metal‐organic source
Authors: Zimowska M. , Lityńska‐Dobrzyńska L. , Olejniczak Z. , Socha R.P. , Gurgul J. , Łątka K.
Published: March 2016

Porous clay heterostructures (PCH) have been prepared through the surfactant directed assembly of organosilica in the galleries of synthetic layered clay mineral Laponite. Fe‐containing PCH nanostructures with nominal (Si + Mg)/Fe = 10 were prepared by post‐synthesis impregnation of porous clay hybrid composites with metal‐organic C6H5FeO. After impregnation, the as‐synthesized Fe–PCH samples were either directly calcined at 550 °C or, prior to calcination, hydrothermally treated in the high pressure reactor. The impact of the PCH composite doping by the trivalent (Fe3+) cations on the physicochemical properties was investigated with the use of spectroscopic methods.

Detailed information on the character and lattice positions occupied by iron, the extent of its incorporation, its local structure and symmetry within samples were provided by comparing the FTIR analysis with the 57Fe Mössbauer spectroscopy and 29Si MAS NMR data. The nature of different Fe species formed after post‐synthesis treatments was determined by Mössbauer spectroscopy and HRTEM. High pressure treatment resulted in the alteration of sample morphology and better, more homogenous dispersion of the Fe species in the composite lattice. FTIR indicated slight impairment of the clay structure in the PCH network followed by surface enrichment with Mg species because of Mg cations leaching from the octahedral sheets as confirmed by XPS study. Copyright © 2016 John Wiley & Sons, Ltd.
Solvothermally Mediated Self‐Assembly of Ultralong Peptide Nanobelts Capable of Optical Waveguiding
Authors: Li Yongxin , Yan Linyin , Liu Kai , Wang Juan , Wang Anhe , Bai Shuo , Yan Xuehai
Published: March 2016

The formation of ultralong peptide crystalline nanobelts using a solvothermal approach from a di‐phenylalanine gel within 10 min, where the self‐assembly process is accelerated by several orders of magnitude compared with the month‐long glutaraldehyde induction method previously reported, has been demonstrated. The solvothermal treatment can facilitate the phase separation of di‐phenylalanine gels while speeding up the kinetics of the intramolecular cyclization reaction and concomitant crystallization. Moreover, the modulation effect of formaldehyde as an additive is revealed, and that a small amount of formaldehyde leads to thicker crystalline platelets capable of curved optical waveguiding that can potentially be applied in advanced bio‐optical and optoelectronic devices, a rare feat with peptide‐based crystals.
Birefringence‐Directed Raman Selection Rules in 2D Black Phosphorus Crystals
Authors: Mao Nannan , Wu Juanxia , Han Bowen , Lin Jingjing , Tong Lianming , Zhang Jin
Published: March 2016

The incident and scattered light engaged in the Raman scattering process of low symmetry crystals always suffer from the birefringence‐induced depolarization. Therefore, for anisotropic crystals, the classical Raman selection rules should be corrected by taking the birefringence effect into consideration. The appearance of the 2D anisotropic materials provides an excellent platform to explore the birefringence‐directed Raman selection rules, due to its controllable thickness at the nanoscale that greatly simplifies the situation comparing with bulk materials. Herein, a theoretical and experimental investigation on the birefringence‐directed Raman selection rules in the anisotropic black phosphorus (BP) crystals is presented. The abnormal angle‐dependent polarized Raman scattering of the Ag modes in thin BP crystal, which deviates from the normal Raman selection rules, is successfully interpreted by the theoretical model based on birefringence. It is further confirmed by the examination of different Raman modes using different laser lines and BP samples of different thicknesses.
North American megadroughts in the Common Era: reconstructions and simulations
Authors: Cook Benjamin I. , Cook Edward R. , Smerdon Jason E. , Seager Richard , Williams A. Park , Coats Sloan , Stahle David W. , Díaz José Villanueva
Published: March 2016

During the Medieval Climate Anomaly (MCA), Western North America experienced episodes of intense aridity that persisted for multiple decades or longer. These megadroughts are well documented in many proxy records, but the causal mechanisms are poorly understood. General circulation models (GCMs) simulate megadroughts, but do not reproduce the temporal clustering of events during the MCA, suggesting they are not caused by the time history of volcanic or solar forcing. Instead, GCMs generate megadroughts through (1) internal atmospheric variability, (2) sea‐surface temperatures, and (3) land surface and dust aerosol feedbacks. While no hypothesis has been definitively rejected, and no GCM has accurately reproduced all features (e.g., timing, duration, and extent) of any specific megadrought, their persistence suggests a role for processes that impart memory to the climate system (land surface and ocean dynamics). Over the 21st century, GCMs project an increase in the risk of megadrought occurrence through greenhouse gas forced reductions in precipitation and increases in evaporative demand. This drying is robust across models and multiple drought indicators, but major uncertainties still need to be resolved. These include the potential moderation of vegetation evaporative losses at higher atmospheric [CO2], variations in land surface model complexity, and decadal to multidecadal modes of natural climate variability that could delay or advance onset of aridification over the the next several decades. Because future droughts will arise from both natural variability and greenhouse gas forced trends in hydroclimate, improving our understanding of the natural drivers of persistent multidecadal megadroughts should be a major research priority. WIREs Clim Change 2016, 7:411–432. doi: 10.1002/wcc.394

This article is categorized under:

Paleoclimates and Current Trends > Paleoclimate

Climate Models and Modeling > Knowledge Generation with Models
Regulatory effects of cotranscriptional RNA structure formation and transitions
Authors: Liu Sheng‐Rui , Hu Chun‐Gen , Zhang Jin‐Zhi
Published: March 2016

RNAs, which play significant roles in many fundamental biological processes of life, fold into sophisticated and precise structures. RNA folding is a dynamic and intricate process, which conformation transition of coding and noncoding RNAs form the primary elements of genetic regulation. The cellular environment contains various intrinsic and extrinsic factors that potentially affect RNA folding in vivo, and experimental and theoretical evidence increasingly indicates that the highly flexible features of the RNA structure are affected by these factors, which include the flanking sequence context, physiochemical conditions, cis RNA–RNA interactions, and RNA interactions with other molecules. Furthermore, distinct RNA structures have been identified that govern almost all steps of biological processes in cells, including transcriptional activation and termination, transcriptional mutagenesis, 5′‐capping, splicing, 3′‐polyadenylation, mRNA export and localization, and translation. Here, we briefly summarize the dynamic and complex features of RNA folding along with a wide variety of intrinsic and extrinsic factors that affect RNA folding. We then provide several examples to elaborate RNA structure‐mediated regulation at the transcriptional and posttranscriptional levels. Finally, we illustrate the regulatory roles of RNA structure and discuss advances pertaining to RNA structure in plants. WIREs RNA 2016, 7:562–574. doi: 10.1002/wrna.1350

This article is categorized under:

RNA Structure and Dynamics > RNA Structure, Dynamics, and Chemistry

RNA Structure and Dynamics > Influence of RNA Structure in Biological Systems

Regulatory RNAs/RNAi/Riboswitches > Regulatory RNAs
Metagenomic analysis of denitrifying wastewater enrichment cultures able to transform the explosive, 3-nitro-1,2,4-triazol-5-one (NTO)
Authors: Eberly Jed O , Indest Karl J , Hancock Dawn E , Jung Carina M , Crocker Fiona H
Published: March 2016

Removal of 3-nitro-1,2,4-triazol-5-one (NTO) was investigated in conjunction with heterotrophic and autotrophic denitrifying growth conditions by a microbial consortium from a wastewater treatment plant. Microcosms were supplemented with molasses, methanol, or thiosulfate. Cultures were passaged twice by transferring 10 % of the culture volume to fresh media on days 11 and 21. Rates of NTO removal were 18.71 ± 0.65, 9.04 ± 2.61, and 4.34 ± 2.72 mg/L/day while rates of nitrate removal were 20.08 ± 1.13, 21.58 ± 1.20, and 24.84 ± 1.26 mg/L/day, respectively, for molasses, methanol, or thiosulfate. Metagenomic analysis showed that Proteobacteria and Firmicutes were the major phyla in the microbial communities. In molasses supplemented cultures, the community profile at the family level changed over time with Pseudomonadaceae the most abundant (67.4 %) at day 11, Clostridiaceae (65.7 %) at day 21, and Sporolactobacillaceae (35.4 %) and Clostridiaceae (41.0 %) at day 29. Pseudomonadaceae was the dominant family in methanol and thiosulfate supplemented cultures from day 21 to 29 with 76.6 and 81.6 % relative abundance, respectively.
Medial to posterior release procedure after failure of functional treatment in clubfoot: A prospective study
Authors: Bocahut Nicolas , Simon Anne-Laure , Mazda Keyvan , Ilharreborde Brice , Souchet Philippe
Published: March 2016

Purpose

Two conservative techniques for clubfoot treatment are still being debated and depend upon the institution's expertise. For >40 years, the current institution has been a pioneer in the development of the physiotherapy method; however, some severe deformities remain resistant to this method which causes pain, sprains, and difficulties wearing shoes. Therefore, a surgical approach was developed simultaneously for the treatment of these residual or recurring clubfeet. The procedure reproduces the same chronological steps by performing forefoot derotation before correcting hindfoot equinus. The aim of the current study was to assess the results of this surgical technique.

Methods

All clubfeet undergoing surgery between October 1995 and February 2009 were prospectively included. Initial severity was based on Dimeglio's classification and final outcomes on the International Clubfoot Study Group (ICFSG) outcome evaluation system. Last follow-up results were assessed by physical examination and radiographs.

Results

A total of 137 patients with severe clubfeet (mean Dimeglio score 12.0) underwent surgery. At the mean follow-up of 10.8 years, mean ICFSG score was 4.3 (range 0–23), and 12 % required revision surgery. The rate of undercorrection and overcorrection was low (17 pes-plano-valgus ft and 11 ft with undercorrection). Eight feet had a fixed deformity.

Conclusions

Severe deformities are more resistant to conservative techniques even for institutions with large experience. These deformities require further treatment, including surgery if necessary. The medial to posterior soft-tissue release is a valuable technique with stable results.

Level of evidence

Level IV.
Circle of Willis Collateral During Temporary Internal Carotid Artery Occlusion I: Observations From Digital Subtraction Angiography
Authors: Lownie Stephen P. , Larrazabal Ramiro , Kole Maximilian K.
Published: March 2016

Introduction: Impaired collateral circulation can lead to stroke during carotid endarterectomy. Carotid stump pressure (CSP) is used as a surrogate measure of collateral flow. The objective was to determine whether anatomical features obtained from digital subtraction angiography correlate with CSP during temporary internal carotid artery occlusion. The second objective was to use these features in combination to predict CSP. Methods: Digital subtraction angiographies from 102 patients obtained before endarterectomy were reviewed for anatomical variables including: degree of ipsilateral and contralateral carotid artery stenosis; patency of the anterior communicating artery; presence of cross-flow into ipsilateral middle cerebral artery branches; and size (< or ≥1 mm calibre) of the ipsilateral proximal anterior cerebral (A1), the contralateral A1, and the ipsilateral posterior communicating arteries. At surgery, systemic mean arterial pressure (MAP) and CSP were recorded. Multiple regression analysis was used to assess for anatomical features significantly associated with CSP. A “predicted CSP” equation was applied to 54 subsequent patients and correlated with measured CSP. Results: Variables correlating with CSP included MAP (p=0.001); the presence of severe contralateral carotid stenosis (p=0.002); patency of the anterior communicating artery (p=0.013); and the size of the contralateral A1 segment (p=0.029). Angiographic cross-flow, ipsilateral A1 size, and ipsilateral posterior communicating artery size were not significant. Predicted CSP correlated significantly with measured CSP (p<0.0001; R2=0.34). Conclusions: Anatomical features and systemic MAP are associated with carotid stump pressure during internal carotid artery occlusion and account for a significant amount of its variation.
A SAR record of early 21st century change in Greenland
Authors: JOUGHIN IAN , SMITH BEN E. , HOWAT IAN M. , MOON TWILA , SCAMBOS TED A.
Published: March 2016

Glaciers in Greenland are changing rapidly. To better understand these changes, we have produced a series of seven synthetic aperture radar (SAR) backscatter mosaics for seven winters during the period from 2000 to 2013. Six of the mosaics were created using RADARSAT Fine-Beam data and the seventh used ALOS-PALSAR Fine-Beam Single-Polarization data. The RADARSAT mosaics are radiometrically calibrated and capture changes in the backscatter coefficient related to melt and other events, particularly the strong melting in the summer of 2012. Comparison of features in the ascending-orbit ALOS mosaic and the descending-orbit RADARSAT mosaics indicate that in areas of smooth to moderate topography their locations are consistent to within a few tens of meters. The locations of features identifiable in the RADARSAT mosaics, which were collected with the same imaging parameters, generally agree to within better than the 20 m posting of the data. With such geometric accuracy, these data establish a record of change in Greenland for the early part of the 21st century, thus providing a baseline that can be compared with new radar and optical datasets.
The finite probe size effect in fluctuation measurements; application to dusty plasmas
Authors: Tolias P. , Ratynskaia S. , de Angelis U. , Lazzaro E.
Published: March 2016

The effect of the finite probe size in plasma fluctuation measurements is revisited for dusty plasmas, where it has been argued that dust leads to a significant low-frequency enhancement in the spectral densities of ion density fluctuations, which can constitute the physical basis of a dust diagnostic technique. Theoretical predictions for the spectral modifications are presented and the dust acoustic mode contribution is analysed. The finite probe size effect is treated within the volume average approach, which introduces geometry dependent form factors that are calculated for spherical and cylindrical probes. The volume average approach is compared with the typically employed cutoff wavenumber approximation for various dust and plasma parameters. The contribution of temperature fluctuations to the spectral density of current fluctuations is also evaluated.
Composites with invisible inclusions: Eigenvalues of ℝ-linear problem
Authors: MITYUSHEV V. V.
Published: March 2016

A new eigenvalue ℝ-linear problem arisen in the theory of metamaterials and neutral inclusions is reduced to integral equations. The problem is constructively investigated for circular non-overlapping inclusions. An asymptotic formula for eigenvalues is deduced when the radii of inclusions tend to zero. The nodal domains conjecture related to univalent eigenfunctions is posed. Demonstration of the conjecture allows to justify that a set of inclusions can be made neutral by surrounding it with an appropriate coating.
Translation semantic variability: How semantic relatedness affects learning of translation-ambiguous words
Authors: BRACKEN JENNIFER , DEGANI TAMAR , EDDINGTON CHELSEA , TOKOWICZ NATASHA
Published: March 2016

Translations often do not align directly across languages, and indirect mappings reduce the accuracy of language learning. To facilitate examination of this issue, we developed a new continuous measure for quantifying the semantic relatedness of words with more than one translation (hereafter translation-ambiguous words). Participants rated the similarity of each translation to every other translation, yielding a Translation Semantic Variability (TSV) score, ranging from 1.00 (unrelated) to 7.00 (related). Then, we determined how relatedness between translations affects translation-ambiguous word learning from German to English. German words with low TSV scores were recognized as translations more slowly and less accurately than German words with high TSV scores. TSV explains unique variance beyond the previously-used dichotomous classification of words as form vs. meaning ambiguous. We propose that the relatedness of the translation alternatives influences learning because it affects the ease with which a one-to-one mapping can be established between form and meaning.
Summary of the Joint Discussion: Atomic Data of Importance for Ultraviolet and X-Ray Astronomy
Authors: Hearn A. G.
Published: March 2016

This Joint Discussion is in two parts. The first part is a description of recent observations which illustrate the need for atomic data and the second part is a description of what atomic data are available or could readily be produced by the latest theoretical and experimental methods. The purpose of this summary is to highlight the immediate requirements for atomic data of current observations which are not met by our present knowledge and thereby indicate where further work is necessary in providing atomic data.

Although this is a discussion of atomic data the problems of assuming local thermodynamic equilibrium have inevitably been raised. The importance of considering whether departures from LTE are significant or not in the interpretation of observations is is clearly illustrated by the work of the Harvard group on the Lyman continuum emitted by the Sun which has shown a departure coefficient as large as 200 for the ground level of hydrogen.
The Determination of Angular Diameters of Stars
Authors: Davis John
Published: March 2016

Ideally the determination of the angular diameter of a star would include the measurement of the distribution of intensity across the stellar disc. However, direct methods of measuring angular diameters have so far lacked adequate ‘signal to noise’ ratio to measure the intensity distribution and it has been the custom, in the first instance, to express the measured angular diameter in terms of the angular diameter of the equivalent uniform disc (θUD). Subsequent use of the angular diameter involves the assumption of a limb-darkening law and the application of an appropriate correction to θUD to find the ‘true’ angular diameter (θLD) of the star (e.g. Hanbury Brown et al., 1967). In this article we will discuss the determination of θUD for single stars and we will not refer further to the more difficult problems of determining intensity distributions involving limb-darkening and rotational effects and of measuring the angular parameters of binary systems.

By itself the angular diameter of a star has no intrinsic value but when it is combined with other observational data it enables basic physical properties of the star to be determined. It is then possible to make a direct comparison of the observed properties of the star with the predictions of theoretical models of stellar atmospheres and interiors. For example, the combination of an angular diameter with the absolute monochromatic flux received from the star (ƒν), corrected for interstellar extinction, yields the absolute emergent flux at the stellar surface (). If the spectral energy distribution for the star is known it can be calibrated absolutely by and hence the effective temperature (Te) of the star can be found (this is equivalent to knowing the bolometric correction for the star and using it with the angular diameter to find Te). In addition to leading to the determination of Te, the absolute surface flux distribution may be compared directly with the predicted flux distributions for theoretical model stellar atmospheres (e.g. Davis and Webb, 1970). For O and early B. type stars a large fraction of the emergent flux is in the far ultra-violet and the effective temperatures cannot be determined from the, at present, incomplete empirical flux curves. In these cases it is possible to obtain an estimate of the effective temperatures by using the values of to calibrate a grid of model atmospheres which have Te as a parameter. In this way, by measuring the angular diameters of stars of different spectral types, it is possible to establish an effective temperature scale.
The Occurrence of Lithium in Stars
Authors: Herbig G. H.
Published: March 2016

My task is to outline our present observational knowledge of the occurrence of lithium in stellar atmospheres. On account of the limited time, I shall not attempt to include a description of the situation in post-main sequence stars. Also for shortness of time, forgive me if I do not stop at each point to give due credit to the astronomers who have contributed to that topic.

The youngest stars we know which are cool enough to exhibit neutral Li are the T Tauri stars, which are in the early stages of contraction toward the main sequence. All these objects that have been adequately observed are very abundant in Li: the range is between 50 and 400 times the so-called ‘solar abundance’, a convenient unit which corresponds to a H/Li ratio by number of atoms of about 1011. It is significant that the average Li content of chondritic meteorites, which are often considered to be samples of the non-volatile, unprocessed material of the original solar nebula, is about 150 on this system, within the range observed in the TTauri stars.
Precession and Galactic Rotation on the Basis of Various Proper Motion Systems
Authors: Fricke W.
Published: March 2016

Previous determinations of precession on the basis of proper motions resulted in corrections to Newcomb’s value of lunisolar precession in the interval per century. From a compilation of several determinations and their reduction to the average of the systems of FK3 and N30 Morgan and Oort (1951) obtained:

per century, where A and B are Oort’s constants. Values in the system of FK4 were derived by Bošniakovich (1965), who applied differential corrections to previous results on the basis of the systematic differences FK4–FK3.
Relative Star Positions from Overlapping Photographic Plates
Authors: Clube S. V. M.
Published: March 2016

An account is given of an investigation to obtain accurate relative star positions from overlapping photographic plates. The method described is quite general, but in the first instance is to be applied to plate material obtained with the new Cape astrometric camera.

The Cape 4-component f/10 20-cm astrometric camera produces a field of 5° square with a scale of 100″ per mm in the focal plane. The telescope is fitted with a yellow filter 12 mm from the focal plane, which in combination with the Ilford-R40 emulsion used, transmits more or less uniformly in the range 5300<λ<6500 and little elsewhere. Within this spectral range, the maximum longitudinal aberration is only 0·75 mm and the images sensibly round out to the edge of the plate. The instrument is currently being used to obtain a complete coverage of the Southern hemisphere down to mv~11·5 such that each plate, effectively 4° square, has overlapping plates centred at each corner and at the middle of each side. In practice, this system of overlapping is applied to a number of zones in declination each about 10° broad. Each plate is taken within 30m of the meridian and is given two 3m exposures above and below the 1950 standard positions, the geometrical plate centre being estimated to be within 20″ of the tangential point. At the time of writing, coverage of the zone −30° to −52° is almost complete, and preparations for the zone 0° to −30° well advanced.
Radio Observations of Angular Structure
Authors: Palmer H. P.
Published: March 2016

Complete information about the angular sizes and structures of discrete radio sources would, in principle, require observations in many position angles and at a large number of resolving powers, of which the highest power must resolve the smallest significant features in the sources. Since some sources are known to have components with differing radio spectra, similar amounts of data would be required at each of several wavelengths. One would then be able to examine statistically the relation between fringe visibility and resolving power at two or three wavelengths, and hence search for structural differences between different types of discrete sources.