bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of different compatibilizers on the rheological, thermomechanical, and morphological properties of HDPE/LLDPE blend‐based nanocomposites
Authors: Passador Fabio Roberto , Ruvolo‐Filho Adhemar Collà , Pessan Luiz Antonio
Published: May 2013

The influence of two different compatibilizers and their combination (maleic anhydride grafted high density polyethylene, HDPE‐g‐MA; maleic anhydride grafted linear low density polyethylene, LLDPE‐g‐MA; and 50/50 wt % mixture of these compatibilizers) on the rheological, thermomechanical, and morphological properties of HDPE/LLDPE/organoclay blend‐based nanocomposites was evaluated. Nanocomposites were obtained by melt‐intercalation in a torque rheometer in two steps. Masterbatches (compatibilizer/nanoclay 2:1) were obtained and subsequently diluted in the HDPE/LLDPE matrix producing nanocomposites with 2.5 wt % of nanoclay. Wide angle X‐ray diffraction (WAXD), steady‐state rheological properties, and transmission electron microscopy (TEM) were used to determine the influence of different compatibilizer systems on intercalation and/or exfoliation process which occurs preferentially in the amorphous phase, and thermomechanical properties. The LLDPE‐g‐MA with a high melt index (and consequently low viscosity and crystallinity) was an effective compatibilizer for this system. Furthermore, the compatibilized nanocomposites with LLDPE‐g‐MA or mixture of HDPE‐g‐MA and LLDPE‐g‐MA exhibited better nanoclay's dispersion and distribution with stronger interactions between the matrix and the nanoclay. These results indicated that the addition of maleic anhydride grafted polyethylene facilitates both, the exfoliation and/or intercalation of the clays and its adhesion to HDPE/LLDPE blend. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1726–1735, 2013
Siloxane‐based segmented poly(urethane‐urea) elastomer: Synthesis and characterization
Authors: Askari Fahimeh , Barikani Mehdi , Barmar Mohamad
Published: May 2013

A series of segmented poly(urethane‐urea) block copolymers were synthesized with varying proportions of polydimethylsiloxane diols in combination with polytetramethylene ether glycol (PTMG) using 4,4'‐methylenediphenyl diisocyanate followed by chain extension with a (50:50 mol %) mixture of 4,4'‐methylene‐bis(3‐chloro‐2,6‐diethylaniline) (M‐CDEA) and 1,4‐butanediol (BD). The molecular structures of polydimethylsiloxane urethane‐ureas were characterized by ATR‐FTIR and 1H‐NMR spectroscopic techniques. Distribution of siloxane domain and its influence on surface roughness were investigated by scanning electron microscopy (SEM) and atomic forced microscopy (AFM), respectively. The mechanical and thermal properties of the elastomers were studied by thermogravimetric analysis, dynamical mechanical thermal analysis, and tensile measurement. The results showed that by incorporation of polydimethylsiloxane diol and M‐CDEA chain extender in polyurethane formulation, some improvements in thermal stability, fire resistance and surface hydrophilicity were achieved. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1743–1751, 2013
Synthesis and solution behavior of hydrophobically associating polyacrylamide containing capsaicin‐like moieties
Authors: Jia Lanni , Yu Liangmin , Li Ru , Yan Xuefeng , Zhang Zhiming
Published: May 2013

A novel hydrophobically associating polyacrylamide (PAAHO) of acrylamide, 2‐acrylamide‐2‐methylpropane sulfonate, capsaicin‐like monomer N‐(4‐hydroxy‐3‐methoxy‐benzyl) acrylamide (HMBA), and hydrophobic monomer octadecyl acrylate was synthesized by micellar copolymerization and characterized by fourier transform infrared spectrum, ultraviolet‐visible spectrum, and thermogravimetric analysis, respectively. By adjusting various factors, a series of PAAHOs with different block structures were prepared. The hydrophobic association properties were then studied by viscometry and fluorescence spectrometry. Solution behavior was examined with respect to polymer concentration, ionic strength, and temperature. Also, the antibacterial activity was investigated. Results show that initiator amount influenced not only the molecular weight but also the yield and composition of resulting copolymers. PAAHOs possess strong thickening capability, and the hydrophobic association is enhanced as hydrophobe content increases. PAAHOs have excellent viscosity retention in brine solution and exhibit unique rheological behavior including a salt‐thickening response. Incorporation of HMBA greatly improves the thermal stability of PAAHO. Moreover, PAAHO is endowed with considerable antibacterial activity against Escherichia coli and Staphylococcus aureus. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1794–1804, 2013
Preparation and properties of glycerin ester of tung oil modified rosin
Authors: Ma Guozhang , Zhang Tong , Wu Jianbing , Hou Caiying , Ling Lixia , Wang Baojun
Published: May 2013

Tung oil modified rosins (TR) were prepared by reaction rosin with different amount of tung oil via Diels‐Alder addition reaction and further used in the formulation of glycerin ester of tung oil modified rosins (GTR) with flexible characteristics. The effects of the amount of tung oil on the bromine value, molecular weight, thermostability, physical, and tackifying properties of GTRs were studied. The results showed that the bromine value of GTRs decreased and molecular weight of GTRs increased with the increase in the amount of tung oil. Meanwhile, increasing the amount of tung oil resulted in a significant decrease in both the softening points and viscosities of GTRs, but a slight increase in the thermostability of GTRs due to the incorporation of the flexible fatty chains into the rigid hydrophenanthrene units in rosins. Applied in PU adhesive as tackifier, the increase of the flexible chains content in GTRs led to an increase first and then decrease in both the miscibility of GTRs with PU and the T‐peel strength of adhesives. The elongation at break of films increased monotonously, but their tensile strengths increased first and then decreased with increasing the flexible chains content in GTRs. GTRs with desired properties were prepared when the tung oil/rosin weight ratios were in the range from10/100 to 40/100. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1700–1706, 2013
Nonparametric permutation and combination‐based multivariate control charts with applications in microelectronics
Authors: Corain Livio , Salmaso Luigi
Published: May 2013

In recent decades, multivariate statistical methods for monitoring and controlling of industrial processes have received increasing attention. Multivariate process control charts such as Hotelling's T2 and multivariate exponentially weighted moving average have gained acceptance as manufacturing process control tools especially for the semiconductor industry. We propose in this paper a novel multivariate nonparametric control chart based on the permutation and nonparametric combination (NPC) methodology. The proposed NPC chart is always an exact inferential procedure for every finite sample size and overcomes some limitations of traditional approaches such as the ability to include a large number of variables. Moreover, NPC chart offers several advantages because it is a robust solution with respect to the true underlying random error distribution, and it is not affected by the problem of the loss of degrees of freedom when keeping fixed the number of observations. Unlike traditional methods, when the number of informative variables increases its power monotonically increases as well (finite sample consistency property of NPC test). As confirmed by an extensive simulation study and by an application to some real case studies in the field of microelectronics, the NPC charts are certainly good alternatives with respect to the traditional multivariate control charts such as Hotelling's T2 especially in cases of asymmetric or heavy‐tailed error distributions. Finally, NPC chart represents a suitable solution for monitoring a multivariate process when the number of observed process variables may be larger than the number of observations. Copyright © 2013 John Wiley & Sons, Ltd.
Efficient Green‐Light‐Emitting Electrochemical Cells Based on Ionic Iridium Complexes with Sulfone‐Containing Cyclometalating Ligands
Authors: Tordera Daniel , Bünzli Andreas M. , Pertegás Antonio , Junquera‐Hernández José M. , Constable Edwin C. , Zampese Jennifer A. , Housecroft Catherine E. , Ortí Enrique , Bolink Henk J.
Published: May 2013

A new approach to obtain green‐emitting iridium(III) complexes is described. The synthetic approach consists of introducing a methylsulfone electron‐withdrawing substituent into a 4‐phenylpyrazole cyclometalating ligand in order to stabilize the highest‐occupied molecular orbital (HOMO). Six new complexes have been synthesized incorporating the conjugate base of 1‐(4‐(methylsulfonyl)phenyl)‐1 H‐pyrazole as the cyclometalating ligand. The complexes show green emission and very high photoluminescence quantum yields in both diluted and concentrated films. When used as the main active component in light‐emitting electrochemical cells (LECs), green electroluminance is observed. High efficiencies and luminances are obtained at low driving voltages. This approach for green emitters is an alternative to the widely used fluorine‐based substituents in the cyclometalating ligands and opens new design possibilities for the synthesis of green emitters for LECs.
A Molecularly Defined Iron‐Catalyst for the Selective Hydrogenation of α,β‐Unsaturated Aldehydes
Authors: Wienhöfer Gerrit , Westerhaus Felix A. , Junge Kathrin , Ludwig Ralf , Beller Matthias
Published: May 2013

A selective iron‐based catalyst system for the hydrogenation of α,β‐unsaturated aldehydes to allylic alcohols is presented. Applying the defined iron–tetraphos complex [FeF(L)][BF4] (L=P(PhPPh2)3) in the presence of trifluoroacetic acid a broad range of aldehydes are reduced in high yields using low catalyst loadings (0.05–1 mol %). Excellent chemoselectivity for the reduction of aldehydes in the presence of other reducible moieties, for example, ketones, olefins, esters, etc. is achieved. Based on the in situ detected hydride species [FeH(H2)(L)]+ a catalytic cycle is proposed that is supported by computational calculations.
Large‐Area Plasmonic Substrate of Silver‐Coated Iron Oxide Nanorod Arrays for Plasmon‐Enhanced Spectroscopy
Authors: Carvalho Waldemir Moura , Volpati Diogo , Nunes Carvalho Vitor A. , Aroca Ricardo F. , Constantino Carlos J. L. , Souza Flavio L.
Published: May 2013

One‐dimensional iron oxide materials fabricated on conducting glass substrates and their unique properties make these nanostructures promising candidates for a wide range of applications. Herein, vertically oriented α‐Fe2O3 nanorod arrays synthesized under hydrothermal conditions over a large area are described, as an active platform for surface‐enhanced resonance Raman scattering (SERRS) and surface‐enhanced fluorescence (SEF). From scanning electron microscopy images the formation of a homogeneous distribution of vertically oriented rods in a large area is confirmed. For activating the localized surface plasmon resonances, which are responsible for SERRS and SEF, a 6 nm layer of Ag is deposited onto the α‐Fe2O3 nanorod arrays by physical vapor deposition to form Ag islands.
Psychodynamic Therapy from the Perspective of Self‐organization. A Concept of Change and a Methodological Approach for Empirical Examination
Authors: Gumz Antje , Geyer Michael , Brähler Elmar
Published: May 2013

Observations from therapeutic practice and a series of empirical findings, for example, those on discontinuous change in psychotherapeutic processes, suggest modelling the therapeutic process as a self‐organizing system with stable and critical instable phases and abrupt transitions. Here, a concept of psychotherapeutic change is presented that applies self‐organization theory to psychodynamic principles. The authors explain the observations and considerations that form the basis of the concept and present some connections with existing findings and concepts. On the basis of this model, they generated two hypotheses regarding the co‐occurrence of instability and discontinuous change and the degree of synchrony between the therapist and patient. A study design to test these hypotheses was developed and applied to a single case (psychodynamic therapy). After each session, patient and therapist rated their interaction. A measure of instability was calculated across the resulting time series. Sequences of destabilization were observed. On the basis of points of extreme instability, the process was divided into phases. Local instability maxima were accompanied by significant discontinuous change. Destabilization was highly synchronous in therapist and patient ratings. The authors discussed the concept and the methodological procedure. The approach enables the operationalization of crises and to empirically assess the significance of critical phases and developments within the therapeutic relationship. Copyright © 2013 John Wiley & Sons, Ltd.

Key Practitioner Message

We present a concept of change that applies self‐organization theory to psychodynamic therapy.

We empirically tested the hypotheses formulated in the concept based on an extract of 125 long‐term psychodynamic therapy sessions. We continuously monitored the therapeutic interaction and calculated a measure of the instability of the assessments.

We identified several sequences of stable and unstable episodes. Episodes of high instability were accompanied by discontinuous change. On the basis of these episodes of high instability, we divided the process into four phases. Mean values of variables differed across these phases.

Destabilization proved to be highly synchronous in therapist and patient ratings.

The approach allows to empirically assess critical phases and developments within the therapeutic relationship.
Effect of the Structural Characteristics of Binary Pt–Ru and Ternary Pt–Ru–M Fuel Cell Catalysts on the Activity of Ethanol Electrooxidation in Acid Medium
Authors: Antolini Ermete
Published: May 2013

In view of their possible use as anode materials in acid direct ethanol fuel cells, the electrocatalytic activity of Pt–Ru and Pt–Ru–M catalysts for ethanol oxidation has been investigated. This minireview examines the effects of the structural characteristics of Pt–Ru, such as the degree of alloying and Ru oxidation state, on the electrocatalytic activity for ethanol oxidation.
Ecological causes of morphological evolution in the three‐spined stickleback
Authors: Spence Rowena , Wootton Robert J. , Barber Iain , Przybylski Mirosław , Smith Carl
Published: May 2013

The central assumption of evolutionary theory is that natural selection drives the adaptation of populations to local environmental conditions, resulting in the evolution of adaptive phenotypes. The three‐spined stickleback (Gasterosteus aculeatus) displays remarkable phenotypic variation, offering an unusually tractable model for understanding the ecological mechanisms underpinning adaptive evolutionary change. Using populations onNorthUist,Scotland we investigated the role of predation pressure and calcium limitation on the adaptive evolution of stickleback morphology and behavior. Dissolved calcium was a significant predictor of plate and spine morph, while predator abundance was not. Stickleback latency to emerge from a refuge varied with morph, with populations with highly reduced plates and spines and high predation risk less bold. Our findings support strong directional selection in three‐spined stickleback evolution, driven by multiple selective agents.
Oxidative Olefination of Secondary Amines­ with Carbon Nucleophiles
Authors: Zhang Yong‐Gang , Xu Jing‐Kun , Li Xi‐Ming , Tian Shi‐Kai
Published: May 2013

An unprecedented olefination reaction of secondary amines with carbon nucleophiles has been developed through C–N/C–H functionalization under metal‐free oxidative conditions. In the presence of a stoichiometric amount of 2,3‐dichloro‐5,6‐dicyano‐1,4‐benzoquinone (DDQ), a range of secondary N‐alkylanilines smoothly underwent oxidative olefination with 2‐alkylazaarenes, acetophenone, and malononitrile to give structurally diverse polysubstituted alkenes in moderate to excellent yields with excellent (E) selectivity. Preliminary mechanistic studies revealed that the oxidative olefination reaction proceeds through amine oxidation followed by imine olefination.
Stereocontrolled Synthesis of 1,3‐Diamino‐2‐ols by Aminohydroxylation of Bicyclic Methylene‐Aziridines
Authors: Weatherly Cale D. , Guzei Ilia A. , Schomaker Jennifer M.
Published: May 2013

Nitrogen‐containing stereotriads, which are defined as compounds with three adjacent stereodefined carbon atoms, are common structural motifs in several biologically relevant compounds. The 1,3‐diamino‐2‐ol motif in particular is an important pharmacophore for which there are limited stereoselective synthetic approaches. In this communication, we describe the aminohydroxylation of a series of bicyclic methylene‐aziridines obtained from the aziridination of a series of homoallenic carbamates. The unusual electronic and steric features of these useful heterocyclic scaffolds render the Os‐catalyzed aminohydroxylation of the exocyclic alkene highly regio‐ and stereoselective. Rearrangement of the proposed N,O‐aminal intermediate to a 1,3‐diamino‐2‐one is followed by reduction with NaBH4 to deliver the desired 1,3‐diamino‐2‐ols in good yields with high diastereomeric ratios.
Counter‐prejudicial training reduces activation of biased associations and enhances response monitoring
Authors: Calanchini Jimmy , Gonsalkorale Karen , Sherman Jeffrey W. , Klauer Karl Christoph
Published: May 2013

Although implicitly measured bias was once assumed to be highly stable, subsequent research has shown that it is, in fact, malleable. One technique for altering implicit bias is through counter‐prejudicial training. At least two broad mechanisms may drive this effect. First, training people to respond in counter‐prejudicial ways may diminish the extent to which biased associations are activated in memory. Second, training may strengthen processes that reduce the influence of biased associations on responses. Participants received either counter‐prejudicial, pro‐prejudicial, or no training and then completed an implicit measure of bias. Application of the quadruple process model revealed support for both mechanisms: Counter‐prejudicial training produced less activation of biased associations as well as enhanced detection of appropriate responses compared with pro‐prejudicial or no training. Implications for the development of bias‐reduction training are discussed. Copyright © 2013 John Wiley & Sons, Ltd.
A new analytical solution for assessing climate change impacts on subsurface temperature
Authors: Kurylyk Barret L. , MacQuarrie Kerry T. B.
Published: May 2013

Groundwater temperature is an important water quality parameter that affects species distributions in subsurface and surface environments. To investigate the response of subsurface temperature to atmospheric climate change, an analytical solution is derived for a one‐dimensional, transient conduction–advection equation and verified with numerical methods using the finite element code SUTRA. The solution can be directly applied to forward model the impact of future climate change on subsurface temperature profiles or inversely applied to produce a surface temperature history from measured borehole profiles. The initial conditions are represented using superimposed linear and exponential functions, and the boundary condition is expressed as an exponential function. This solution expands on a classic solution in which the initial and boundary conditions were restricted to linear functions. The exponential functions allow more flexibility in matching climate model projections (boundary conditions) and measured temperature–depth profiles (initial conditions). For example, measured borehole temperature data from the Sendai Plain and Tokyo, Japan, were used to demonstrate the improved accuracy of the exponential function for replicating temperature–depth profiles. Also, the improved accuracy of the exponential boundary condition was demonstrated using air temperature anomaly data from the Intergovernmental Panel on Climate Change. These air temperature anomalies were then used to forward model the effect of surficial thermal perturbations in subsurface environments with significant groundwater flow. The simulation results indicate that recharge can accelerate shallow subsurface warming, whereas upward groundwater discharge can enhance deeper subsurface warming. Additionally, the simulation results demonstrate that future groundwater temperatures obtained from the proposed analytical solution can deviate significantly from those produced with the classic solution. Copyright © 2013 John Wiley & Sons, Ltd.
Dietary flavonoid, lignan and antioxidant capacity and risk of hepatocellular carcinoma in the European prospective investigation into cancer and nutrition study
Authors: Zamora‐Ros Raul , Fedirko Veronika , Trichopoulou Antonia , González Carlos A. , Bamia Christina , Trepo Elisabeth , Nöthlings Ute , Duarte‐Salles Talita , Serafini Mauro , Bredsdorff Lea , Overvad Kim , Tjønneland Anne , Halkjær Jytte , Fagherazzi Guy , Perquier Florence , Boutron‐Ruault Marie‐Christine , Katzke Verena , Lukanova Annekatrin , Floegel Anna , Boeing Heiner , Lagiou Pagona , Trichopoulos Dimitrios , Saieva Calogero , Agnoli Claudia , Mattiello Amalia , Tumino Rosario , Sacerdote Carlotta , Bueno‐de‐Mesquita H. Bas , Peeters Petra H.M. , Weiderpass Elisabete , Engeset Dagrun , Skeie Guri , Argüelles Marcial Vicente , Molina‐Montes Esther , Dorronsoro Miren , Tormo María José , Ardanaz Eva , Ericson Ulrika , Sonestedt Emily , Sund Malin , Landberg Rikard , Khaw Kay‐Tee , Wareham Nicholas J. , Crowe Francesca L. , Riboli Elio , Jenab Mazda
Published: May 2013

Limited epidemiological evidence suggests a protective role for plant foods rich in flavonoids and antioxidants in hepatocellular cancer (HCC) etiology. Our aim was to prospectively investigate the association between dietary intake of flavonoids, lignans and nonenzymatic antioxidant capacity (NEAC) and HCC risk. Data from the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort including 477,206 subjects (29.8% male) recruited from ten Western European countries, was analyzed. Flavonoid, lignan and NEAC intakes were calculated using a compilation of existing food composition databases linked to dietary information from validated dietary questionnaires. Dietary NEAC was based on ferric reducing antioxidant capacity (FRAP) and total radical‐trapping antioxidant parameter (TRAP). Hepatitis B/C status was measured in a nested case–control subset. During a mean follow‐up of 11‐years, 191 incident HCC cases (66.5% men) were identified. Using Cox regression, multivariable adjusted models showed a borderline nonsignificant association of HCC with total flavonoid intake (highest versus lowest tertile, HR = 0.65, 95% CI: 0.40–1.04; ptrend = 0.065), but not with lignans. Among flavonoid subclasses, flavanols were inversely associated with HCC risk (HR = 0.62, 95% CI: 0.39–0.99; ptrend = 0.06). Dietary NEAC was inversely associated with HCC (FRAP: HR 0.50, 95% CI: 0.31–0.81; ptrend = 0.001; TRAP: HR 0.49, 95% CI: 0.31–0.79; ptrend = 0.002), but statistical significance was lost after exclusion of the first 2 years of follow‐up. This study suggests that higher intake of dietary flavanols and antioxidants may be associated with a reduced HCC risk.
Assessing the Emotional Quality of Parent–Child Relationships Involving Young Children with Special Needs: Applying the Constructs of Emotional Availability and Expressed Emotion
Authors: Kubicek Lorraine F. , Riley Karen , Coleman Jeanine , Miller Gloria , Linder Toni
Published: May 2013

Sensitive, responsive, and dependable relationships are key to providing the support and encouragement all children need for optimal development. Unfortunately, parents and their young children with special needs often face behavioral challenges and life stressors related to the children's delays/disabilities that can interfere with the development of emotionally positive relationships. This study explores the usefulness of two standardized measures, the Emotional Availability Scales (EAS; Z. Biringen, J.L. Robinson, & R.N. Emde, 1998) and the Five Minute Speech Sample (FMSS; A.B. Magana‐Amato, 1993), for assessing the emotional quality of relationships between parents and their children aged 3 years or younger with special needs. To date, neither measure has been used extensively with this population. Each of the 38 participating dyads included a child with an identified delay/disability. Results of the EAS suggest that it is a viable measure for assessing the relationships of parents and their young children with special needs. The FMSS results, though less clear, suggest that with certain limits, it also is a viable measure for use with this population. This study can inform the debate about the need to integrate early childhood mental health practices into all child/family services and to provide appropriate training to meet the growing demand for such relationship‐based services.
Optical induction of muscle contraction at the tissue scale through intrinsic cellular amplifiers
Authors: Yoon Jonghee , Choi Myunghwan , Ku Taeyun , Choi Won Jong , Choi Chulhee
Published: May 2013

The smooth muscle cell is the principal component responsible for involuntary control of visceral organs, including vascular tonicity, secretion, and sphincter regulation. It is known that the neurotransmitters released from nerve endings increase the intracellular Ca2+level in smooth muscle cells followed by muscle contraction. We herein report that femtosecond laser pulses focused on the diffraction‐limited volume can induce intracellular Ca2+increases in the irradiated smooth muscle cell without neurotransmitters, and locally increased intracellular Ca2+levels are amplified by calcium‐induced calcium‐releasing mechanisms through the ryanodine receptor, a Ca2+channel of the endoplasmic reticulum. The laser‐induced Ca2+increases propagate to adjacent cells through gap junctions. Thus, ultrashort‐pulsed lasers can induce smooth muscle contraction by controlling Ca2+, even with optical stimulation of the diffraction‐limited volume. This optical method, which leads to reversible and reproducible muscle contraction, can be used in research into muscle dynamics, neuromuscular disease treatment, and nanorobot control. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Estradiol Production by the Bidder's Organ of the Toad Rhinella arenarum (Amphibia, Anura). Seasonal Variations in Plasma Estradiol
Authors: Scaia María Florencia , Regueira Eleonora , Volonteri María Clara , Ceballos Nora Raquel
Published: May 2013

In bufonids, the Bidder's organ (BO), located in the anterior pole of the testis, is sometimes referred to as a rudimentary ovary because of the presence of previtellogenic follicles. In males of Rhinella arenarum it has been demonstrated that some follicles are vitellogenic and also express several steroidogenic enzymes in follicular cells. The purpose of this study is to describe seasonal variations in plasma estradiol (E2) and in aromatase activity of the BO, and to determine the capacity of the BO to synthesize E2 from cholesterol in males of R. arenarum. E2 was determined by radioimmunoassay and aromatase activity was measured by transformation of radioactive substrates into products. Results indicate that plasma E2 reached the highest concentration in April and the lowest one in animals captured in June, showing a progressive increase to the end of the year. Plasma E2 and total activity of aromatase in the BO were significantly lower during the pre‐reproductive season than during the reproductive and post‐reproductive seasons. It was also demonstrated that the BO is able to produce E2 from endogenous substrates throughout the year. No correlation was found between plasma E2 and total BO weight, while there was a significant correlation between plasma E2 and total activity of aromatase, and between plasma E2 and E2 produced in vitro. Taken together, these results demonstrate seasonal variations in plasma E2, in bidderian total activity of aromatase and, that the BO of adult males of R. arenarum is able to produce E2 from endogenous substrates. J. Exp. Zool. 319A:355–364, 2013. © 2013 © 2013 Wiley Periodicals, Inc.
Statistics of whistler mode waves in the outer radiation belt: Cluster STAFF‐SA measurements
Authors: Agapitov Oleksiy , Artemyev Anton , Krasnoselskikh Vladimir , Khotyaintsev Yuri V. , Mourenas Didier , Breuillard Hugo , Balikhin Michael , Rolland Guy
Published: May 2013

ELF/VLF waves play a crucial role in the dynamics of the radiation belts and are partly responsible for the main losses and the acceleration of energetic electrons. Modeling wave‐particle interactions requires detailed information of wave amplitudes and wave normal distribution over L‐shells and over magnetic latitudes for different geomagnetic activity conditions. We performed a statistical study of ELF/VLF emissions using wave measurements in the whistler frequency range for 10 years (2001–2010) aboard Cluster spacecraft. We utilized data from the STAFF‐SA experiment, which spans the frequency range from 8 Hz to 4 kHz. We present distributions of wave magnetic and electric field amplitudes and wave normal directions as functions of magnetic latitude, magnetic local time, L‐shell, and geomagnetic activity. We show that wave normals are directed approximately along the background magnetic field (with the mean value of θ—the angle between the wave normal and the background magnetic field, about 10°–15°) in the vicinity of the geomagnetic equator. The distribution changes with magnetic latitude: Plasmaspheric hiss normal angles increase with latitude to quasi‐perpendicular direction at ∼35°–40° where hiss can be reflected; lower band chorus are observed as two wave populations: One population of wave normals tends toward the resonance cone and at latitudes of around 35°–45° wave normals become nearly perpendicular to the magnetic field; the other part remains quasi‐parallel at latitudes up to 30°. The observed angular distribution is significantly different from Gaussian, and the width of the distribution increases with latitude. Due to the rapid increase of θ, the wave mode becomes quasi‐electrostatic, and the corresponding electric field increases with latitude and has a maximum near 30°. The magnetic field amplitude of the chorus in the day sector has a minimum at the magnetic equator but increases rapidly with latitude with a local maximum near 12°–15°. The wave magnetic field maximum is observed in the night sector at L>7 during low geomagnetic activity (at L∼5 for Kp>3). Our results confirm the strong dependence of wave amplitude on geomagnetic activity found in earlier studies.
Instability of some equatorially trapped waves
Authors: Constantin Adrian , Germain Pierre
Published: May 2013

A high‐frequency asymptotics approach within the Lagrangian framework shows that some exact equatorially trapped three‐dimensional waves are linearly unstable when their steepness exceeds a specific threshold.
Analysis of the potential and limitations of microwave radiometry for the retrieval of sea surface temperature: Definition of MICROWAT, a new mission concept
Authors: Prigent C. , Aires F. , Bernardo F. , Orlhac J.‐C. , Goutoule J.‐M. , Roquet H. , Donlon C.
Published: May 2013

The sensitivity of passive microwave observations to the sea surface temperature (SST) is carefully analyzed, with the objective of designing an optimized satellite instrument, MICROwave Wind And Temperature (MICROWAT), dedicated to an “all‐weather” estimation of the SST at high spatial resolution (15 km). Our study stresses the importance of low‐frequency observations around 6 GHz for accurate SST retrieval. Compared to the 11 GHz channel, the 6 GHz channel provides more sensitivity to the low SSTs and offers lower instrument noise, thanks to possibly broader channel bandwidths. However, it requires much larger antenna size for a given spatial resolution. Two instrument concepts have been suggested, one using a classic real aperture antenna and the other using synthetic interferometric antennas. This first analysis shows that 2‐D interferometric systems would be very complex and would not satisfy the user requirements in terms of SST accuracy. A 1‐D interferometric system could be proposed, but its development requires additional investigation. A dedicated conical scanner onboard a microsatellite with a 6 m antenna and channels at 6.9 and 18.7 GHz (both with V and H polarizations) can provide an SST accuracy of 0.3 K with a 15 km spatial resolution, with today's technology.
Spatial and temporal patterns of the recent warming of the Amazon forest
Authors: Jiménez‐Muñoz Juan C. , Sobrino José A. , Mattar Cristian , Malhi Yadvinder
Published: May 2013

In recent years, several studies have addressed the response of Amazonian forests to drought by analyzing anomalies in vegetation indices retrieved from satellite sensors. Attention was paid to Amazonia because of two major droughts in 2005 and 2010, which were considered amongst the most severe in a century. These drought events have been associated with increased tree mortality and a temporary shutdown of the Amazon carbon sink. The mortality has been attributed to water stress anomalies, though an additional effect might have resulted from thermal anomalies. Variations in surface temperature are believed to be closely related to drought events, but very few studies have analyzed this variable over the Amazonian region. Here we examine Moderate Resolution Imaging Spectroradiometer (MODIS) land surface temperature (LST) products from the period 2000–2012 in Amazonia. We detected anomalous warming during the dry season (July to September) in the drought years 2005 and 2010, as well as in the years 2009, 2011, and 2012 and to a lesser extent in 2008, which implies anomalous warming in 5 of the last 7 years. Recent analysis also shows warming in 2012 from June to August. Land and sea temperature records were also examined using reanalysis data from 1979 to present. Our results show good agreement between MODIS LST and reanalysis data from 2000 to present and a clear link between warming over the Amazonian region and anomalies in sea surface temperature in both the Atlantic and Pacific regions.
Physical modeling of three‐dimensional intermediate beach morphodynamics
Authors: Michallet H. , Castelle B. , Barthélemy E. , Berni C. , Bonneton P.
Published: May 2013

Experiments have been performed in a large wave tank in order to study the morphodynamics of rip current systems. Both accretive and erosive shore‐normal wave conditions were applied, the beach evolving through all the states within the intermediate beach classification, under the so‐called down‐state (accretive) and up‐state (erosive) morphological transitions. Results show that any prescribed change in the wave conditions drastically increases the rate at which the morphology changes. The surf zone morphology tends toward a steady state when running a given wave climate for a long duration. We quantitatively describe a full down‐state sequence characterized by the progressive evolution of an alongshore‐uniform bar successively into a crescentic plan shape, a bar and rip channel morphology, and a terrace. From the analysis of a large data set of dense Eulerian measurements and bathymetric surveys, we depict several feedback mechanisms associated with wave‐driven rip current circulation, wave nonlinearities and the seabed evolution. At first, a positive feedback mechanism drives a rapid increase in the rate of morphological change, beach three‐dimensionality, and rip intensity. By the time the sandbar evolves into a bar and rip morphology, a negative feedback mechanism, characterized by a decaying beach change rate and an increasing beach alongshore uniformity, overwhelms the former mechanism. An erosive sequence characterized by both an overall offshore bar migration and an increase in beach three‐dimensionality is also described.
Meander dynamics: A reduced‐order nonlinear model without curvature restrictions for flow and bed morphology
Authors: Ottevanger W. , Blanckaert K. , J. Uijttewaal W. S. , de Vriend H. J.
Published: May 2013

Reduced‐order models remain essential tools for meander modeling, especially for processes at large length scales and long time scales, probabilistic simulations, rapid assessments, or when input data are scarce or uncertain. Present reduced‐order meander models consider their dependent variables either as small‐amplitude variations compared to a basic state (linearity) or as varying gradually in a spatial sense (gradual variation). In a prequel, Blanckaert and de Vriend () derived a nonlinear reduced‐order hydrodynamic model without curvature restrictions and showed that linearity or gradual curvature variations assumptions do not hold in strongly curved channels. Moreover, in strongly curved channels, a nonlinear feedback mechanism causes the secondary flow strength to be smaller than its linear mild‐curvature equivalent. In the limit of mild‐amplitude variations and mild curvature, their nonlinear meander flow model simplifies to a well‐known linear formulation. The present paper extends this nonlinear modeling to the bed morphology in strongly curved bends, making use of Exner's sediment conservation principle. Furthermore, the model quantifying the relative influence of the downslope gravitational force is refined by considering nonlinear effects. The coupled nonlinear flow and bed morphology model yields satisfactory results for the bed topography, whereas the corresponding linear model strongly overpredicts the magnitude of the transverse bed slope. Analysis of the forcing mechanisms indicate that this erroneous behavior is caused by an overestimation of the upslope drag force due to the secondary flow.
Diffusion tensor imaging of normal‐appearing white matter in unilateral cerebral arterial occlusive disease
Authors: Meng Xiangshui , Wang Qing , Hou Jinwen , Zhang Xiaoming , Wang Enguo , Li Qilu , Zeng Qingshi , Wang Qian , Li Chuanfu , Ma Xiangxing
Published: May 2013

Purpose

To use MR with diffusion tensor imaging (DTI) and conventional and high b value to assess diffusion changes in normal‐appearing white matter (NAWM) in patients with unilateral, severe stenosis, or occlusion of the middle cerebral artery (MCA).

Materials and Methods

In total, 28 patients with NAWM and unilateral, severe stenosis, or occlusion of the MCA underwent DTI with b values 1000 and 2200 s/mm2 at 3.0T MR. Fractional anisotropy (FA), apparent diffusion coefficient (ADC), radial diffusivity (eigenvalues λ1, λ2), and axial diffusivity (eigenvalue λ3) were measured for the ipsilateral and contralateral corona radiata.

Results

Mean FA was significantly lower for the ipsilateral than contralateral corona radiata with high b value, 2200 s/mm2, and ipsilateral corona radiata with conventional low b value, 1000 s/mm2 (all P < 0.01). Mean ADC, λ1, λ2, and λ3 were significantly higher for the ipsilateral than contralateral corona radiata with high b value (all P < 0.05) but not for ipsilateral than contralateral corona radiata with low b value (P > 0.05).

Conclusion

DTI with a high b value detects diffusion changes in NAWM in patients with unilateral, severe stenosis, or occlusion of the MCA not seen with conventional b value or conventional MRI contrasts. J. Magn. Reson. Imaging 2013;38:650–654. © 2012 Wiley Periodicals, Inc.
A simple and accurate dynamical modeling of quantum‐dot semiconductor optical amplifiers
Authors: Taleb Hussein , Abedi Kambiz , Golmohammadi Saeed.
Published: May 2013

In this article, quantum‐dot semiconductor optical amplifiers (QD‐SOAs) have been modelled using state space method. To derive this model, we have manipulated the rate equation model of the QD‐SOA, where the average values of the occupation probabilities along the QD‐SOA cavity are considered as the state variables of the system. Using these variables, the distance dependence of the rate equations is eliminated. The derived state space model gives the optical gain and output signal of the amplifier with a high accuracy. Simulation results show that the derived model is not only much simpler and faster than conventional rate equation models, but also the optical gain and output signal of the investigated QD‐SOA are calculated with a higher precision compared to the rate equation model. Copyright © 2013 John Wiley & Sons, Ltd.
Changes in extreme temperature and precipitation in the Arab region: long‐term trends and variability related to ENSO and NAO
Authors: Donat M. G. , Peterson T. C. , Brunet M. , King A. D. , Almazroui M. , Kolli R. K. , Boucherf Djamel , Al‐Mulla Anwar Yousuf , Nour Abdourahman Youssouf , Aly Ahmed Attia , Nada Tamer Ali Ali , Semawi Muhammad M. , Al Dashti Hasan Abdullah , Salhab Tarek G. , El Fadli Khalid I. , Muftah Mohamed K. , Dah Eida Sidaty , Badi Wafae , Driouech Fatima , El Rhaz Khalid , Abubaker Mohammed J. Y. , Ghulam Ayman S. , Erayah Amani Sanhouri , Mansour Maher Ben , Alabdouli Waleed O. , Al Dhanhani Jemie Salem , Al Shekaili Majed N.
Published: May 2013

A workshop was held in Casablanca, Morocco, in March 2012, to enhance knowledge of climate extremes and their changes in the Arab region. This workshop initiated intensive data compilation activities of daily observational weather station data from the Arab region. After conducting careful control processes to ensure the quality and homogeneity of the data, climate indices for extreme temperatures and precipitation were calculated.

This study examines the temporal changes in climate extremes in the Arab region with regard to long‐term trends and natural variability related to ENSO and NAO. We find consistent warming trends since the middle of the 20th Century across the region. This is evident in the increased frequencies of warm days and warm nights, higher extreme temperature values, fewer cold days and cold nights and shorter cold spell durations. The warming trends seem to be particularly strong since the early 1970s. Changes in precipitation are generally less consistent and characterised by a higher spatial and temporal variability; the trends are generally less significant. However, in the western part of the Arab region, there is a tendency towards wetter conditions. In contrast, in the eastern part, there are more drying trends, although, these are of low significance.

We also find some relationships between climate extremes in the Arab region and certain prominent modes of variability, in particular El Niño‐Southern Oscillation (ENSO) and North Atlantic Oscillation (NAO). The relationships of the climate extremes with NAO are stronger, in general, than those with ENSO, and are particularly strong in the western part of the Arab region (closer to the Atlantic Ocean). The relationships with ENSO are found to be more significant towards the eastern part of the area of study. © 2013 Royal Meteorological Society
Potassium‐fertilizer management in winter oilseed‐rape production in China
Authors: Ren Tao , Lu Jianwei , Li Hui , Zou Juan , Xu Huali , Liu Xiaowei , Li Xiaokun
Published: May 2013

Optimal potassium (K) fertilization is beneficial for oilseed‐rape (Brassica napus L.) yield and quality. However, the discrepancy between the high K demand of winter oilseed rape and low soil fertility and insufficient potassium input has limited the sustainable development of oilseed‐rape production. A series of on‐farm experiments in the key winter oilseed‐rape domains of China was conducted from 2004 to 2010 to evaluate K‐fertilizer management for winter oilseed rape. Currently, the average NH4OAc‐extractable K content in the 0–20 cm soil layer is 89.1 mg kg–1 indicative of “slight deficiency”. In addition, farmers in China usually fail to use sufficient K fertilizer in oilseed‐rape production, the average mineral‐potassium‐fertilizer input in 2010 being only 35 kg K ha–1, far lower than the recommended rate of potassium for winter oilseed rape. Adequate potassium fertilization significantly raises seed yield. The average yield‐increase rate for the major production regions due to K‐fertilizer application was 18.5%, and the average K fertilizer–use efficiency 36.1%. Based on the negative correlation between yield response to potassium fertilization and available soil K content, a soil‐K‐test index was established for winter oilseed rape with a threshold value for NH4OAc‐extractable soil K of 135 mg kg–1. When available soil K‐content is below this threshold value, more K fertilizer should be applied to achieve high seed yield and to increase soil fertility. The major challenge for K‐fertilizer management in winter oilseed‐rape production in China will be to guide farmers in the different regions in making reasonable use of K fertilizer through soil K‐testing technology in order to maintain both seed yield and soil fertility.
Acid‐extractable potassium in agricultural soils: Source minerals assessed by differential and quantitative X‐ray diffraction
Authors: Andrist‐Rangel Ylva , Simonsson Magnus , Öborn Ingrid , Hillier Stephen
Published: May 2013

Different extraction methods are used world‐wide in routine soil analysis to estimate long‐term potassium (K) reserves for plants. In Sweden, K extracted with 2 M HCl at 100°C (KHCl) is frequently used, although with limited understanding of the phases extracted. In the present study, we quantified the effects of this extraction on soil minerals in particle size fractions ranging from clay to sand, and estimated their relative contribution to KHCl. The study included three Swedish long‐term agricultural field experiments with texture ranging from loamy sand to silty clay, as well as mineral specimens of K feldspar. Total weight loss of particle size fractions was determined, and quantitative and differential X‐ray powder diffraction (QXRD, DXRD), applied on solids before and after extraction, was used to quantify the dissolution of individual mineral phases. QXRD and DXRD included spray‐drying of samples, addition of an internal standard and full pattern fitting, where a combination of mineral‐standard XRD traces was matched with the experimental one. Our results show that KHCl was primarily associated with clay minerals concentrated in the two finest fractions (2–20 and < 2 μm). Highly expandable and mixed‐layer phyllosilicates were quantitatively the most important minerals dissolved. The K was released from micaceous layers in mixed‐layer phyllosilicates with a vermiculitic character. Whether di‐ or trioctahedral, a shared property of the dissolved phases was that they were rich in Fe. In the loamy sand, the coarser fractions (20–2000 μm), where feldspars were prominent, accounted for 35% of KHCl. According to DXRD, there was no significant decrease in K feldspars in any of the samples, and KHCl data for the feldspar specimens suggest that clay minerals contributed at least 70% of KHCl also in the loamy sand. Our study provides insights about the soil minerals that contribute to the long‐term K delivery capacity of soils and an explanation for the prior observation that KHCl is a dynamic fraction that can be affected by management.