bluuebunny/crossref_metadata_2025 huggingface dataset:
Properties of polycarbonate containing BaTiO3 nanoparticles
Authors: Lomax J. F. , Fontanella J. J. , Edmondson C. A. , Wintersgill M. C. , Wolak M. A. , Westgate M. A. , Lomax E. A. , Lomax P. Q. , Bogle X. , Rúa A. , Greenbaum S. G.
Published: March 2014

The real part of the relative permittivity, ε′, and dielectric loss, tan δ, have been determined at audio frequencies at temperatures from about 5 K to 350 K for nano-composites composed of BaTiO3 nanoparticles and polycarbonate. The room temperature breakdown strength was also measured and thermal analysis, nuclear magnetic resonance and scanning electron microscopy studies were carried out. For some films the nanoparticles were surface-treated (STNP) while for others they were not (UNP). For concentrations of UNP greater than about 3.4 vol. %, ε′ is much larger than expected on the basis of laws of mixing. On the other hand, ε′ for materials made using STNP is well-behaved. Correspondingly, increased loss (ε″ or tan δ) in the vicinity of room temperature is observed for the materials made from UNP. The anomalously large values of relative permittivity and increased loss are attributed to the presence of large aggregates in the materials made using the UNP. For both UNP-and STNP-based materials, the breakdown strength is found to decrease as nanoparticle concentration increases. The breakdown strength for the materials made using STNP is found to be larger for all concentrations than for those containing UNP despite the presence of large aggregates in some of the STNP-based materials. This shows that breakdown is strongly affected by the nanoparticle surfaces and/or the interface layer. It is also found that the breakdown strength for materials made using UNP increases as particle size increases. Finally, variable temperature and pressure proton nuclear magnetic resonance relaxation measurements were made to assess the effect of nanoparticle inclusion on polymer motion, and the effects were found to be very minor.
Mechanical properties of individual InAs nanowires studied by tensile tests
Authors: Li X. , Wei X. L. , Xu T. T. , Ning Z. Y. , Shu J. P. , Wang X. Y. , Pan D. , Zhao J. H. , Yang T. , Chen Q.
Published: March 2014

Mechanical properties of individual InAs nanowires (NWs) synthesized by metal organic chemical vapor deposition (MOCVD) and molecular beam epitaxy (MBE) methods are studied by in-situ tensile tests in a scanning electron microscope and their fracture strength and Young's modulus are obtained. The two types of NWs both exhibit brittle fracture with a maximum elastic strain up to ∼10%. Their fracture strength distributes in a similar range of ∼2–5 GPa with a general trend of increasing with NW volume decrease, which is well described by Weibull statistic with a smaller Weibull modulus and a higher characteristic strength for MOCVD NWs. Young's modulus is determined to be 16–78 GPa with an average value of 45 GPa and no dependence on NW diameter for MOCVD NWs and 34–79 GPa with an average value of 58 GPa for MBE NWs.
Magnetic tunnel junctions for magnetic field sensor by using CoFeB sensing layer capped with MgO film
Authors: Takenaga Takashi , Tsuzaki Yosuke , Yoshida Chikako , Yamazaki Yuichi , Hatada Akiyoshi , Nakabayashi Masaaki , Iba Yoshihisa , Takahashi Atsushi , Noshiro Hideyuki , Tsunoda Koji , Aoki Masaki , Furukawa Taisuke , Fukumoto Hiroshi , Sugii Toshihiro
Published: March 2014

We evaluated MgO-based magnetic tunnel junctions (MTJs) for magnetic field sensors with spin-valve-type structures in the CoFeB sensing layer capped by an MgO film in order to obtain both top and bottom interfaces of MgO/CoFeB exhibiting interfacial perpendicular magnetic anisotropy (PMA). Hysteresis of the CoFeB sensing layer in these MTJs annealed at 275 °C was suppressed at a thickness of the sensing layer below 1.2 nm by interfacial PMA. We confirmed that the CoFeB sensing layers capped with MgO suppress the thickness dependences of both the magnetoresistance ratio and the magnetic behaviors of the CoFeB sensing layer more than that of the MTJ with a Ta capping layer. MgO-based MTJs with MgO capping layers can improve the controllability of the characteristics for magnetic field sensors.
Exchange bias magnetism in films of NiFe/(Ni,Fe)O nanocrystallite dispersions
Authors: Hsiao C.-H. , Desautels R. D. , van Lierop J. , Lin K.-W. , Chi C.-C. , Wang S. , Lin T.-L. , Ouyang H.
Published: March 2014

Ni3Fe/(Ni,Fe)O thin films having a nanocrystallite dispersion morphology were prepared by a reactive ion beam-assisted deposition technique. The crystallite sizes of these dispersion-based films were observed to decrease from 8.4 ± 0.3 nm to 3.4 ± 0.3 nm as the deposition flow-rate increased from 2.78% to 7.89% O2/Ar. Thin film composition was determined using selective area electron diffraction images and Multislice simulations. Through a detailed analysis of high resolution transmission electron microscopy images, the nanocrystallites were determined to be Ni3Fe (a ferromagnet), NiO, and FeO (both antiferromagnets). It was determined that the interfacial molar Ni3Fe ratio in the nanocrystallite dispersions increased slightly at first, then decreased as the oxygen content was increased; at 7.89% O2/Ar, the interfacial molar ratio was essentially zero (only NiO and FeO remained). For nanocrystallite dispersion films grown with O2/Ar flow-rate greater than 7.89%, no interfacial (intermixed) Ni3Fe phase was detected, which resulted in no measurable exchange bias. Comparing the exchange bias field between the nanocrystallite dispersion films at 5 K, we observed a decrease in the magnitude of the exchange bias field as the nanocrystallite size decreased. The exchange bias coupling for all samples measured set in at essentially the same temperature (i.e., the exchange bias blocking temperature). Since the ferromagnetic/anti-ferromagnetic (FM/AFM) contact area in the nanocrystallite dispersion films increased as the nanocrystallite size decreased, the increase in the magnitude of the exchange bias could be attributed to larger regions of defects (vacancies and bond distortions) which occupied a significant portion of the FM/AFM interfaces in the nanocrystallite dispersion films.
A violet emission in ZnS:Mn,Eu: Luminescence and applications for radiation detection
Authors: Ma Lun , Jiang Ke , Liu Xiao-tang , Chen Wei
Published: March 2014

We prepared manganese and europium co-doped zinc sulfide (ZnS:Mn,Eu) phosphors and used them for radiation detection. In addition to the red fluorescence at 583 nm due to the d-d transition of Mn ions, an intense violet emission at 420 nm is newly observed in ZnS:Mn,Eu phosphors. The emission is related to Eu2+ doping but only appears at certain Eu2+ concentrations. It is found that the intensity of the 420 nm violet fluorescence is X-ray does-dependent, while the red fluorescence of 583 nm is not. The ratio of fluorescence intensities at 420 nm and 583 nm has been monitored as a function of X-ray doses that exposed upon the ZnS:Mn,Eu phosphors. Empirical formulas are provided to estimate the doses of applied X-ray irradiation. Finally, possible mechanisms of X-ray irradiation induced fluorescence quenching are discussed. The intense 420 nm emission not only provides a violet light for solid state lighting but also offers a very sensitive method for radiation detection.
Long term Raman spectral study of power-dependent photodamage in red blood cells
Authors: de Oliveira Marcos A. S. , Smith Zachary J. , Knorr Florian , de Araujo Renato E. , Wachsmann-Hogiu Sebastian
Published: March 2014

We monitored time-dependent changes in the Raman spectra of optically trapped red blood cells. By fitting the Raman peaks of individual spectra over time, high-precision time evolutions of peak positions and intensities were obtained. These changes are dependent on the trapping laser power. Characteristic times for these changes were determined for each laser power by fitting the time courses with multi-exponential curves. Raman spectral dynamics showed significant and irreversible changes as a function of trapping duration that we attribute to a combination of photodamage of hemoglobin at short times followed by diffusion of hemoglobin out of the cell at longer times.
High-pressure sintering behavior of α″-Fe16N2 nanopowder
Authors: Takagi Kenta , Akada Misaho , Ozaki Kimihiro , Kobayashi Naoya , Ogawa Tomoyuki , Ogata Yasunobu , Takahashi Migaku
Published: March 2014

α″-Fe16N2 nanopowder was sintered at high-pressure and low temperature in order to explore its feasibility as a bulk magnet. TEM observation confirmed that the nanopowder was densely consolidated by sintering at a pressure of 1.2 GPa and temperatures around 200 °C. Increasing the sintering temperature enhanced the densification, leading to a suppression of oxidization. However, XRD analysis revealed that sintering at 222 °C caused the decomposition α″ → α-Fe + ε-Fe3N, which reduced the saturated magnetization (Ms) and coercivity (Hc). Consequently, sintering at 190 °C produced a dense magnet that retained the Ms of the raw powder due to the avoidances of oxidization and decomposition. On the other hand, it was found that Hc degrades after sintering, which is believed to be due to magnetic interaction between the particles.
Multiferroism and enhancement of material properties across the morphotropic phase boundary of BiFeO3-PbTiO3
Authors: Amorín H. , Correas C. , Fernández-Posada C. M. , Peña O. , Castro A. , Algueró M.
Published: March 2014

Strong phase-change magnetoelectric responses have been anticipated by a first-principles investigation of phases in the perovskite BiFeO3-BiCoO3 solid solution, specifically at the morphotropic phase boundary (MPB) between the multiferroic rhombohedral and tetragonal polymorphs. This might be a general property of multiferroic MPBs and a novel promising approach for room temperature magnetoelectricity, which requires the identification of suitable material systems. We present here a comprehensive description of the electrical and electromechanical properties across one such system; the perovskite BiFeO3-PbTiO3 solid solution. All the temperature dependence of dielectric permittivity, ferroelectric hysteresis loops, and piezoelectric coefficients have been obtained, and are discussed in relation to the previously reported perovskite structural evolution. Results show ceramic materials to be very promising for ferroelectric random access memories (remnant polarization as high as 63 μC cm−2 with a comparatively low coercive field of 4.5 kV mm−1 for MPB compositions) and high temperature electromechanical transduction (crystal piezoelectric coefficient of 87 pC N−1 with a Curie temperature above 873 K). Moreover, the occurrence of phase changes between the monoclinic and tetragonal polymorphs under high electric fields is indicated, while the canted antiferromagnetic character of the phases involved is corroborated.
Magnetic, transport, and structural properties of SrRuO3 thin films
Authors: Majcher A. M. , Rode K. , Coey J. M. D. , Stamenov P.
Published: March 2014

Thin films of the oxide ferromagnetic metal SrRuO3 (SRO) are studied, in view of their potential use within oxide-based spin electronic devices. Here, their epitaxial growth on Si-compatible SrTiO3 substrates is demonstrated by pulsed laser deposition. Detail on their initial, structural, magnetic, and magnetotransport characterisation is also provided. In particular, resistivity and Hall data are interpreted within a two/three carrier model, above TC. Below TC, some information about the anisotropy of the Fermi surface effective elipsoids (∼1:4) is recovered. The low-temperature saturation magnetisation approaches 1 μB/Ru, with an uniaxial anisotropy of above 0.6 MJm–3. Despite its low TC = 160 K, and in view of its relatively low carrier mobility, it is reasoned that SRO could be utilized as the electrode layer in low-temperature all-oxide-MTJ (Magnetic Tunnel Junction) demonstrators and as a seed layer for other ferromagnetic oxides, at and above room temperature.
Investigating the trade-offs of microwave susceptors in energetic composites: Microwave heating versus combustion performance
Authors: Crane C. A. , Pantoya M. L. , Weeks B. L.
Published: March 2014

Recently, microwave technology has been used to ignite energetic materials when studies showed that metal powders readily absorb microwave energy. This study investigates adding a graphite susceptor to an energetic composite consisting of aluminum (Al) and iron (III) oxide (Fe2O3) and examines microwave coupling to the sample. In a companion study, the combustion of this thermite as a function of susceptor concentration was also studied to evaluate the trade-off between enhancing microwave coupling and flame propagation speed. Results show that graphite enhances microwave coupling up to 10% by mass concentration but reduces heating at higher percentages that exceed a percolation threshold. As susceptor concentrations increased greater than one mass percent, the flame propagation speed correspondingly decreased.
A study on the evolution of dielectric function of ZnO thin films with decreasing film thickness
Authors: Li X. D. , Chen T. P. , Liu P. , Liu Y. , Liu Z. , Leong K. C.
Published: March 2014

Dielectric function, band gap, and exciton binding energies of ultrathin ZnO films as a function of film thickness have been obtained with spectroscopic ellipsometry. As the film thickness decreases, both real (ε1) and imaginary (ε2) parts of the dielectric function decrease significantly, and ε2 shows a blue shift. The film thickness dependence of the dielectric function is shown related to the changes in the interband absorption, discrete-exciton absorption, and continuum-exciton absorption, which can be attributed to the quantum confinement effect on both the band gap and exciton binding energies.
Kinetics of monolayer graphene growth by segregation on Pd(111)
Authors: Mok H. S. , Ebnonnasir A. , Murata Y. , Nie S. , McCarty K. F. , Ciobanu C. V. , Kodambaka S.
Published: March 2014

Using in situ low-energy electron microscopy and density functional theory calculations, we follow the growth of monolayer graphene on Pd(111) via surface segregation of bulk-dissolved carbon. Upon lowering the substrate temperature, nucleation of graphene begins on graphene-free Pd surface and continues to occur during graphene growth. Measurements of graphene growth rates and Pd surface work functions establish that this continued nucleation is due to increasing C adatom concentration on the Pd surface with time. We attribute this anomalous phenomenon to a large barrier for attachment of C adatoms to graphene coupled with a strong binding of the non-graphitic C to the Pd surface.
Excitation of multiple trapped-eigenmodes in terahertz metamolecule lattices
Authors: Born N. , Al-Naib I. , Jansen C. , Ozaki T. , Morandotti R. , Koch M.
Published: March 2014

We report on the excitation of sharp Fano-like resonances in lattices of metamolecules composed of two differing types of metaatoms. The proposed structures exhibit modes originating from the individual metaatoms as well as a very sharp mode from the collective excitation of the metamolecule lattice as a whole. Next-generation thin film sensors (e.g., for bio/chemical hazard detectors) could especially benefit from such artificial materials. Having multiple modes at different spectral positions enables the characterization of dispersive materials, while the high Q-factors of the eigenmodes lead to a very high sensitivity.
A new nanomaterial synthesized from size-selected, ligand-free metal clusters
Authors: Li X. , Wepasnick K. , Tang X. , Fairbrother D. H. , Bowen K. H. , Dollinger A. , Strobel C. H. , Huber J. , Mangler T. , Luo Y. , Proch S. , Gantefoer G.
Published: March 2014

Thins films are synthesized by deposition of size-selected Mon− cluster anions on an inert substrate. Scanning tunneling microscopy pictures indicate that the deposited material consists of individual particles with diameters corresponding to the size of the preformed clusters from the gas phase. Previous attempts to manufacture cluster materials from metals failed since these clusters coalesced at room temperature. Our data suggest the possibility to synthesize new nanomaterials from clusters of high fusing metals. This may prove to be the key to harness size-dependent and tuneable properties of clusters for creating novel classes of functional tailor-made materials.
FeN foils by nitrogen ion-implantation
Authors: Jiang Yanfeng , Al Mehedi Md , Fu Engang , Wang Yongqiang , Wang Jian-Ping
Published: March 2014

Iron nitride samples in foil shape (free standing, 500 nm in thickness) were prepared by a nitrogen ion-implantation method. To facilitate phase transformation, the samples were bonded on the substrate followed by a post-annealing step. By using two different substrates, single crystal Si and GaAs, structural and magnetic properties of iron nitride foil samples prepared with different nitrogen ion fluences were characterized. α″-Fe16N2 phase in iron nitride foil samples was obtained and confirmed by the proposed approach. A hard magnetic property with coercivity up to 780 Oe was achieved for the FeN foil samples bonded on Si substrate. The feasibility of using nitrogen ion implantation techniques to prepare FeN foil samples up to 500 nm thickness with a stable martensitic phase under high ion fluences has been demonstrated. A possible mechanism was proposed to explain this result. This proposed method could potentially be an alternative route to prepare rare-earth-free FeN bulk magnets by stacking and pressing multiple free-standing thick α″-Fe16N2 foils together.
Electrodeposition of Au/Ag bimetallic dendrites assisted by Faradaic AC-electroosmosis flow
Authors: Ji Jianlong , Li Pengwei , Sang Shengbo , Zhang Wendong , Zhou Zhaoying , Yang Xing , Dong Hualai , Li Gang , Hu Jie
Published: March 2014

Au/Ag bimetallic dendrites were synthesized successfully from the corresponding aqueous solution via the AC electrodeposition method. Both of the morphologies and compositions could be tuned by the electrolyte concentration and AC frequency. The prepared bimetallic dendrites were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectrometer (EDS), transmission electron microscopy (TEM) and UV–vis spectroscopy. The underlying dendrite growth mechanism was then proposed in the context of the Directed Electrochemical Nanowires Assembly (DENA) models. Owing to the unscreened voltage dropping in the electrolyte bulk, electromigration dominates the species flux process, and cations tend to accumulate in areas with strong electric field intensity, such as electrode edges. Moreover, Faradaic AC-electro-osmosis (ACEO) flow could increase the effective diffusion layer thickness in these areas during the electrochemical reaction, and leads to dendrite growth. Further Micro-Raman observations illustrated that the Au/Ag bimetallic dendrites exhibited pronounced surface-enhanced Raman scattering (SERS) activity, using 4-mercaptopyridine (4-MP) as model molecules.
Derivation of naïve human embryonic stem cells
Authors: Ware Carol B. , Nelson Angelique M. , Mecham Brigham , Hesson Jennifer , Zhou Wenyu , Jonlin Erica C. , Jimenez-Caliani Antonio J. , Deng Xinxian , Cavanaugh Christopher , Cook Savannah , Tesar Paul J. , Okada Jeffrey , Margaretha Lilyana , Sperber Henrik , Choi Michael , Blau C. Anthony , Treuting Piper M. , Hawkins R. David , Cirulli Vincenzo , Ruohola-Baker Hannele
Published: March 2014

Significance

We report on generation of nontransgenic, naïve human pluripotent cells that represent the developmentally earliest state described for human established cells. Existing human ES cell lines in the later primed state can be toggled in reverse to naïve by exposure to histone deacetylase inhibitors prior to naïve culture. A new line was established directly from an eight-cell embryo under naïve culture conditions. We describe the naïve state in humans and show that naïve human ES cells have expanded endoderm developmental capacity.
Dynamic association of the PI3P-interacting Mon1-Ccz1 GEF with vacuoles is controlled through its phosphorylation by the type 1 casein kinase Yck3
Authors: Lawrence Gus , Brown Christopher C. , Flood Blake A. , Karunakaran Surya , Cabrera Margarita , Nordmann Mirjana , Ungermann Christian , Fratti Rutilio A.
Published: March 2014

Maturation of organelles in the endolysosomal pathway requires exchange of the early endosomal GTPase Rab5/Vps21 for the late endosomal Rab7/Ypt7. The Rab exchange depends on the guanine nucleotide exchange factor activity of the Mon1-Ccz1 heterodimer for Ypt7. Here we investigate vacuole binding and recycling of Mon1-Ccz1. We find that Mon1-Ccz1 is absent on vacuoles lacking the phosphatidic acid phosphatase Pah1, which also lack Ypt7, the phosphatidylinositol 3-kinase Vps34, and the lipid phosphatidylinositol 3-phosphate (PI3P). Interaction of Mon1-Ccz1 with wild-type vacuoles requires PI3P, as shown in competition experiments. We also find that Mon1 is released from vacuoles during the fusion reaction and its release requires its phosphorylation by the type 1 casein kinase Yck3. In contrast, Mon1 is retained on vacuoles lacking Yck3 or when Mon1 phosphorylation sites are mutated. Phosphorylation and release of Mon1 is restored with addition of recombinant Yck3. Together the results show that Mon1 is recruited to endosomes and vacuoles by PI3P and, likely after activating Ypt7, is phosphorylated and released from vacuoles for recycling.
Translational and posttranslational regulation of XIAP by eIF2α and ATF4 promotes ER stress–induced cell death during the unfolded protein response
Authors: Hiramatsu Nobuhiko , Messah Carissa , Han Jaeseok , LaVail Matthew M. , Kaufman Randal J. , Lin Jonathan H.
Published: March 2014

Endoplasmic reticulum (ER) protein misfolding activates the unfolded protein response (UPR) to help cells cope with ER stress. If ER homeostasis is not restored, UPR promotes cell death. The mechanisms of UPR-mediated cell death are poorly understood. The PKR-like endoplasmic reticulum kinase (PERK) arm of the UPR is implicated in ER stress–induced cell death, in part through up-regulation of proapoptotic CCAAT/enhancer binding protein homologous protein (CHOP). Chop−/− cells are partially resistant to ER stress–induced cell death, and CHOP overexpression alone does not induce cell death. These findings suggest that additional mechanisms regulate cell death downstream of PERK. Here we find dramatic suppression of antiapoptosis XIAP proteins in response to chronic ER stress. We find that PERK down-regulates XIAP synthesis through eIF2α and promotes XIAP degradation through ATF4. Of interest, PERK's down-regulation of XIAP occurs independently of CHOP activity. Loss of XIAP leads to increased cell death, whereas XIAP overexpression significantly enhances resistance to ER stress–induced cell death, even in the absence of CHOP. Our findings define a novel signaling circuit between PERK and XIAP that operates in parallel with PERK to CHOP induction to influence cell survival during ER stress. We propose a “two-hit” model of ER stress–induced cell death involving concomitant CHOP up-regulation and XIAP down-regulation both induced by PERK.
Intrinsic activity in cells and the brain
Authors: Bray Dennis
Published: March 2014

Motile cells such as bacteria, amoebae, and fibroblasts display a continual level of energy-consuming reactions involving the cytoskeleton and signal pathways, regardless of whether or not they are actually migrating. I draw parallels between these “silent signals” and the intrinsic activity of the human brain, especially that associated with the brain stem. In both cases, it can be argued that the organism continually rehearses possible future actions, so it can act quickly and accurately when suitable cues are received from the environment.
Systematic identification of pathological lamin A interactors
Authors: Dittmer Travis A. , Sahni Nidhi , Kubben Nard , Hill David E. , Vidal Marc , Burgess Rebecca C. , Roukos Vassilis , Misteli Tom
Published: March 2014

Laminopathies are a collection of phenotypically diverse diseases that include muscular dystrophies, cardiomyopathies, lipodystrophies, and premature aging syndromes. Laminopathies are caused by >300 distinct mutations in the LMNA gene, which encodes the nuclear intermediate filament proteins lamin A and C, two major architectural elements of the mammalian cell nucleus. The genotype–phenotype relationship and the basis for the pronounced tissue specificity of laminopathies are poorly understood. Here we seek to identify on a global scale lamin A–binding partners whose interaction is affected by disease-relevant LMNA mutations. In a screen of a human genome–wide ORFeome library, we identified and validated 337 lamin A–binding proteins. Testing them against 89 known lamin A disease mutations identified 50 disease-associated interactors. Association of progerin, the lamin A isoform responsible for the premature aging disorder Hutchinson–Gilford progeria syndrome, with its partners was largely mediated by farnesylation. Mapping of the interaction sites on lamin A identified the immunoglobulin G (IgG)–like domain as an interaction hotspot and demonstrated that lamin A variants, which destabilize the Ig-like domain, affect protein–protein interactions more globally than mutations of surface residues. Analysis of a set of LMNA mutations in a single residue, which result in three phenotypically distinct diseases, identified disease-specific interactors. The results represent a systematic map of disease-relevant lamin A interactors and suggest loss of tissue-specific lamin A interactions as a mechanism for the tissue-specific appearance of laminopathic phenotypes.
Implementation of two-component advective flow solution in xspec
Authors: Debnath Dipak , Chakrabarti Sandip K. , Mondal Santanu
Published: March 2014

Spectral and temporal properties of black hole candidates can be explained reasonably well using Chakrabarti–Titarchuk solution of two-component advective flow (TCAF). This model requires two accretion rates, namely the Keplerian disc accretion rate and the halo accretion rate, the latter being composed of a sub-Keplerian, low-angular-momentum flow which may or may not develop a shock. In this solution, the relevant parameter is the relative importance of the halo (which creates the Compton cloud region) rate with respect to the Keplerian disc rate (soft photon source). Though this model has been used earlier to manually fit data of several black hole candidates quite satisfactorily, for the first time, we made it user friendly by implementing it into xspec software of Goddard Space Flight Center (GSFC)/NASA. This enables any user to extract physical parameters of the accretion flows, such as two accretion rates, the shock location, the shock strength, etc., for any black hole candidate. We provide some examples of fitting a few cases using this model. Most importantly, unlike any other model, we show that TCAF is capable of predicting timing properties from the spectral fits, since in TCAF, a shock is responsible for deciding spectral slopes as well as quasi-periodic oscillation frequencies.
Structural Changes of Starch Molecules in Barley Grains During Germination
Authors: Chu Shang , Hasjim Jovin , Hickey Lee T. , Fox Glen , Gilbert Robert G.
Published: March 2014

The germination of barley grains is an important step in malt production for beer brewing. This study examines the changes in starch molecular structure in barley grains under optimal conditions for sprouting. Two barley varieties were tested: Schooner and Grimmett, which are low and moderate dormancy grains, with >90 and <5% of grains germinating within two days in sprouting conditions, respectively. The barley grains were germinated in humid conditions after being soaked in excess water for 24 h. The grain weight and starch content of Schooner decreased significantly (P < 0.05) with germination time, whereas those of Grimmett showed no significant changes (P > 0.05). The starch chain‐length distributions, analyzed from enzymatically debranched starch molecules with size‐exclusion chromatography, indicated that the shorter amylopectin branches of Schooner were degraded at a faster rate than its longer amylopectin branches, which was also confirmed by the decreasing degree of branching with germination time. The changes in starch molecular structure of Grimmett grains were less apparent. The results of this study showed that barley grains containing shorter starch chains can produce sugars more quickly, which indicates that starch structure can serve as one of the specifications when selecting barley grains for brewing.
Location-Specific Fungicide Resistance Profiles and Evidence for Stepwise Accumulation of Resistance in Botrytis cinerea
Authors: Li Xingpeng , Fernández-Ortuño Dolores , Chen Shuning , Grabke Anja , Luo Chao-Xi , Bridges William C. , Schnabel Guido
Published: March 2014

The fungicide resistance profiles to seven chemical classes of fungicides were investigated in 198 Botrytis cinerea isolates from five blackberry fields and 214 B. cinerea isolates from 10 strawberry fields of North and South Carolina. Populations of B. cinerea tended to have a single dominant, location-specific resistance profile that consisted of resistance to multiple fungicides in fields sprayed weekly with site-specific fungicides. The most prevalent profile in blackberry fields consisted of resistance to thiophanate-methyl, pyraclostrobin, and boscalid. The most prevalent resistance profile found in conventional strawberry fields consisted of resistance to thiophanate-methyl, pyraclostrobin, boscalid, and cyprodinil. A statistical model revealed that multifungicide resistance patterns did not evolve randomly in populations from both crops. Instead, strains resistant to thiophanate-methyl were more likely to acquire resistance to pyraclostrobin, the resulting dual-resistant population was more likely to acquire resistance to boscalid, the resulting triple-resistant population was more likely to acquire resistance to cyprodinil, and the resulting quadruple-resistant population was more likely to acquire resistance to fenhexamid (strawberry population only) compared with random chance. Resistance to iprodione and fludioxonil evolved from a pool of strains with different fungicide resistance profiles. Resistance to thiophanate-methyl, pyraclostrobin, boscalid, and fenhexamid in blackberry isolates was, without exception, based on target gene mutations, including E198A and E198V in β-tubulin, G143A in cytochrome b, H272Y and H272R in SdhB, and F412I in Erg27, respectively. A new genotype associated with fenhexamid resistance was found in one strain (i.e., Y408H and deletion of P298). Fungicide-resistant strains were present but rare in an unsprayed blackberry field, where some unique phenotypes, including low and medium resistance to fludioxonil, had emerged in the absence of fungicide pressure. The isolates resistant to fludioxonil had effective dose that inhibited 50% of mycelial growth values of 0.16 μg/ml (low resistance) and 0.32 and 0.38 μg/ml (medium resistance) and were also resistant to the anilinopyrimidine fungicide cyprodinil, indicating that this and similar phenotypes will eventually be selected by continued applications of the fludioxonil + cyprodinil premixture Switch. This study shows that multifungicide-resistant phenotypes are common in conventionally maintained strawberry and blackberry fields and that resistance to multiple fungicides evolved from stepwise accumulation of single resistances.
A Model for Multiseasonal Spread of Verticillium Wilt of Lettuce
Authors: Wu B. M. , Subbarao K. V.
Published: March 2014

Verticillium wilt, caused by Verticillium dahliae, is a destructive disease in lettuce, and the pathogen is seedborne. Even though maximum seed infestation rates of <5% have been detected in commercial lettuce seed lots, it is necessary to establish acceptable contamination thresholds to prevent introduction and establishment of the pathogen in lettuce production fields. However, introduction of inoculum into lettuce fields for experimental purposes to determine its long term effects is undesirable. Therefore, we constructed a simulation model to study the spread of Verticillium wilt following pathogen introduction from seed. The model consists of four components: the first for simulating infection of host plants, the second for simulating reproduction of microsclerotia on diseased plants, the third for simulating the survival of microsclerotia, and the fourth for simulating the dispersal of microsclerotia. The simulation results demonstrated that the inoculum density–disease incidence curve parameters and the dispersal gradients affect disease spread in the field. Although a steep dispersal gradient facilitated the establishment of the disease in a new field with a low inoculum density, a long-tail gradient allowed microsclerotia to be dispersed over greater distances, promoting the disease spread in fields with high inoculum density. The simulation results also revealed the importance of avoiding successive lettuce crops in the same field, reducing survival rate of microsclerotia between crops, and the need for breeding resistance against V. dahliae in lettuce cultivars to lower the number of microsclerotia formed on each diseased plant. The simulation results, however, suggested that, even with a low seed infestation rate, the pathogen would eventually become established if susceptible lettuce cultivars were grown consecutively in the same field for many years. A threshold for seed infestation can be established only when two of the three drivers of the disease—(i) low microsclerotia production per diseased plant, (ii) long-tail dispersal gradient, and (iii) low microsclerotia survival between lettuce crops—are present.
When heat casts a spell on the DNA damage checkpoints
Authors: Turner Thomas , Caspari Thomas
Published: March 2014

Peregrine Laziosi (1265–1345), an Italian priest, became the patron saint of cancer patients when the tumour in his left leg miraculously disappeared after he developed a fever. Elevated body temperature can cause tumours to regress and sensitizes cancer cells to agents that break DNA. Why hyperthermia blocks the repair of broken chromosomes by changing the way that the DNA damage checkpoint kinases ataxia telangiectasia mutated (ATM) and ataxia telangiectasia and Rad3-related (ATR) are activated is an unanswered question. This review discusses the current knowledge of how heat affects the ATR–Chk1 and ATM–Chk2 kinase networks, and provides a possible explanation of why homeothermal organisms such as humans still possess this ancient heat response.
Spatial density and ambient scent: effects on consumer anxiety
Authors: Poon Tina , Grohmann Bianca
Published: March 2014

Purpose

– This replication and extension of Hirsch and Gruss examines the impact of spatial density and ambient scent on consumers' spatial perception and anxiety. The paper aims to discuss these issues.

Design/methodology/approach

– A 2 (spatial density: high, low)×3 (ambient scent: no scent, scent associated with spaciousness, scent associated with enclosed spaces) between-participants experimental design was implemented in a laboratory setting. A pretest determined scent selection and manipulation checks were successful.

Findings

– Spatial perception was influenced by spatial density, but not ambient scent. Ambient scent and spatial density interacted, such that consumers' anxiety levels significantly increased under conditions of low spatial density combined with an ambient scent associated with spaciousness, and directionally increased under conditions of high spatial density combined with ambient scent associated with enclosed space.

Research limitations/implications

– This research was conducted in a laboratory setting in order to increase experimental control. An exploration of the strength of the observed effects in a field (retail) setting would be insightful.

Practical implications

– Results of this study suggest that retailers need to consider both spatial density and choice of ambient scent carefully in order to reduce consumers' anxiety levels.

Originality/value

– This research is one of the few to consider the impact of spatial density and ambient scent on consumers' anxiety levels. The use of a between-participants design and the experimental manipulation of both spatial density and ambient scent results in a more rigorous test of the scent – anxiety relation observed in previous research.
Something old, something new: culture and CEO compensation revisited
Authors: Takacs Haynes Katalin
Published: March 2014

Purpose

– This study is a replication of Tosi and Greckhamer's work examining how uncertainty avoidance, power distance, individualism and masculinity/femininity are related to total CEO pay, the ratio of variable to total CEO pay and the ratio of CEO pay to the pay of the lowest level employees in 23 countries. Its main purpose is to investigate whether the replication confirms, questions or extends the results of TG2004.

Design/methodology/approach

– Tosi and Greckhamer used generalized linear modeling (GLS) to analyze the relationships between Hofstede's four cultural dimensions and CEO compensation. In the replication, the author used GLS to retest the original seven hypotheses with more recent data from Hofstede and test the same hypotheses relying on cultural values and practices scores from the GLOBE study. Further, using firm-level data unavailable for the original study, the author analyzed fixed and random effects in mixed models.

Findings

– The replication generally confirms the findings of the original study for the effects of power distance, individualism and masculinity on CEO total pay. Results are mixed or indicate the lack of significant effect for other relationships.

Research limitations/implications

– This study reexamines the effects of country-level contextual variables in the area of CEO compensation.

Originality/value

– The replication presents firm-level CEO compensation and firm performance data from 21 countries, extending the original study and unveiling possible spurious effects.
Health-improving lifestyles of organic and functional food consumers
Authors: Irene Goetzke Beate , Spiller Achim
Published: March 2014

Purpose

– The desire for health and well-being is a strong driver in the food market. Scientific publications show that health is an important motive for both functional and organic food consumption. The aim of this study is to investigate whether functional and organic food consumers have the same understanding of health, and which health and well-being improving lifestyles are characteristic for them. Based on this, the authors identify dimensions for a wellness-orientated lifestyle model.

Design/methodology/approach

– In order to measure the different well-being and health lifestyles, AIO dimensions were adapted to theoretical wellness concepts. The results of the conducted factor and multiple OLS regression analyses are based on the data of an online survey of 500 German consumers.

Findings

– Consumers of functional food have a similar concept of health and well-being to organic consumers, but differ in certain aspects in their way of achieving this. The purchase of organic and functional food is driven by different lifestyles. Overall, the results confirm the link between organic food and an active lifestyle, as well as functional food and a passive lifestyle.

Practical implications

– The paper contributes to the discussion of health in marketing and especially in the food industry. The results reveal which kinds of lifestyle food marketing should be considered in a target group specific product communication and positioning.

Originality/value

– This study contributes to the understanding of consumer behaviour, especially in the organic and functional food segment. It highlights the importance of health for both food types and also important differences in the understanding of wellness. Moreover, the results reveal first dimensions for a wellness-orientated lifestyle approach – especially for the food market.
E-learning portal for professional development in cancer care
Authors: Shaw Tim , McGregor Deborah , Sinclair Sue , Sutherland Robert , Munro Ana , Ross Jackie
Published: March 2014

Purpose

– Cancer care is complex and an integrated cancer pathway involves many health professionals in a variety of care settings using many skills. The widely distributed and heterogeneous nature of the cancer workforce raises significant challenges with respect to professional development. Cancer Learning is a government-funded initiative designed to provide access to a wide range of quality online learning resources for all health care professionals involved in the care of cancer patients and their families. The purpose of this paper is to discuss these issues.

Design/methodology/approach

– A multi-phase project, led by a consortium of national stakeholders in cancer care, informed the design, build, and deployment of Cancer Learning; an online, evidence based, information and learning portal to support professional development of health professionals across the continuum of cancer care in Australia. An action research approach allowed for an iterative process of ongoing dynamic evaluation and improvement of this workforce improvement resource.

Findings

– The National Government Agency, Cancer Australia's Cancer Learning online hub has been supporting the professional development requirements of cancer care professionals since the site deployment in 2007. Since launch, site usage continues to grow and evaluations have been positive. Time constraints of health professionals continue to be a major barrier to sustained online learning participation.

Originality/value

– This research recount of the development and implementation of an Australia first national online learning initiative highlights the rigorous approach undertaken for the delivery of a quality evidence-based resource for the professional development of all health professionals involved in the delivery of cancer care.
Temporal experiences of e-learning by distance learners
Authors: Leeds Beverly
Published: March 2014

Purpose

– The purpose of this paper is to explore experiences of e-learners in relation to their time preferences, and to examine how technology changes temporal culture in e-learning.

Design/methodology/approach

– A pilot study using multiple methods of data collection to provide a rich picture of the experience of e-learners in relation to temporal flexibility. Taking a narrative approach it analysed data from a survey, time tracking data as well as data from online discussion boards, learners’ assignments and short telephone interviews.

Findings

– The study found e-learners may experience temporal culture shock when starting to study online for the first time. It highlights the need to explore an individual's time preference and to consider the temporal culture of the e-learning programme.

Research limitations/implications

– It highlights that the issue of time is still missing from educational studies and suggests that temporal aspects are included in e-learning research studies. This is a small exploratory study but it indicates the need for further research to explore the potential for temporal culture shock and influence of e-learner time preferences.

Practical implications

– Designing an e-learning environment for learners needs to consider learner time preferences to ensure that temporal flexibility is a realised benefit, not a barrier to learning. The temporal culture of the online learning environment also needs to be made explicit so that learner expectations can be managed.

Originality/value

– It contributes to the literature on e-learning in the higher education context by providing a temporal lens to explore learner experiences. It is of value to educationalists and learning technologists designing, delivering or evaluating e-learning programmes. Online learners may also benefit from its findings.
Emancipation and/or oppression? Conceptualizing dimensions of criticality in entrepreneurship studies
Authors: Verduijn Karen , Dey Pascal , Tedmanson Deirdre , Essers Caroline
Published: March 2014

Purpose

– The purpose of this paper is to use the attribute “critical” as a sensitizing concept to emphasize entrepreneurship's role in overcoming extant relations of exploitation, domination and oppression. It builds on the premise that entrepreneurship not only brings about new firms, products and services but also new openings for more liberating forms of individual and collective existence.

Design/methodology/approach

– Honing in on Calaset al.'s (2009) seminal piece on critical entrepreneurship studies, and building on Laclau's (1996) conceptualization of emancipation as intimately related to oppression, the paper explores different interpretations of emancipation and discuss these from a critical understanding of entrepreneurship. The paper then employs these interpretations to introduce and “classify” the five articles in this special issue.

Findings

– The editorial charts four interpretations of emancipation along two axes (utopian-dystopian and heterotopian-paratopian), and relates these to various strands of critical entrepreneurship research. United by a general commitment to positive change, each interpretation champions a different take on what might comprise the emancipatory or oppressive potential of entrepreneurship.

Originality/value

– As the emancipatory aspect of entrepreneurship has attracted increasing attention among entrepreneurship researchers, the paper formulates a tentative framework for furthering views on the emancipatory aspects of entrepreneurship as a positive phenomenon in critical research – which to date has tended to be preoccupied with the “dark side” of entrepreneurship.
Extending the concept and modularization of project management maturity with adaptable, human and customer factors
Authors: Pasian Beverly
Published: March 2014

Purpose

– The conceptual and modularization of project management maturity models is based on the principle of process control. This research was designed to challenge these boundaries to reveal non-process factors. The paper aims to discuss these issues.

Design/methodology/approach

– A multimethod research design was used with a “qual⇒Qual” sequence. This is a development in MM design theory, with its reliance on an initial qualitative stage that, despite being first, is insufficient to collecting sufficient data to answer the research question. A second stage, involving a more dominant qualitative, is necessary.

Findings

– Multiple non-process factors are attributed to a mature project management capability responsible for undefined projects. They include “human factors” such as trust, attitude, motivation and attitude, along with increased customer involvement and a more adaptable organizational environment.

Research limitations/implications

– The challenge put forward in this research was for project management maturity theorists to recognize the possibility of finding maturity in a project management capability responsible for undefined projects. This challenge has been met. The focus can now turn to other environments where other project types (undefined or not) are also being managed using processes (and/or practices) that are not necessarily definable, repeatable, predictable and unique to that setting.

Originality/value

– An adaptable model has been created that contains multiple factors that can be used in their current relationships or changed to accommodate multiple project and project management scenarios. Further work will create weights for each factor that will further specify the relative value of each, thereby enhancing the adaptable nature of the model.