bluuebunny/crossref_metadata_2025 huggingface dataset:
Introduction to special section on Global Dimming and Brightening
Authors: Wild Martin
Published: February 2010

Global dimming and brightening is a popular expression which refers to the recent observational evidence for substantial decadal variations in solar radiation reaching the Earth's surface. For the first time, a special section is dedicated to this rapidly growing field of research. A comprehensive collection of more than 20 papers sheds new light on the phenomenon of global dimming and brightening. Here I provide a brief introduction and guideline to the special section and place the individual papers into context. To facilitate orientation in this special section, the papers are grouped according to the specific aspects of global dimming and brightening that they address.
Toward restoring the net carbon sink function of degraded peatlands: Short‐term response in CO2 exchange to ecosystem‐scale restoration
Authors: Waddington J. M. , Strack M. , Greenwood M. J.
Published: February 2010

Northern peatlands represent a globally important stock of soil carbon and have acted as a net sink of atmospheric CO2 throughout the Holocene. Disturbance for horticultural peat extraction disrupts ecosystem function and converts these ecosystems to large, persistent sources of carbon dioxide (CO2). This study investigates the effect of ecosystem‐scale restoration on growing season CO2 exchange in a peatland by comparing a restored site to a neighboring nonrestored section for 1 year prerestoration (1999) and 3 years postrestoration (2000–2002). Prior to restoration, less than 23% of the site was vegetated, and it was a source of 245 g C m−2 to the atmosphere during the growing season (May to early October). Following restoration, the water table remained deep, and soil moisture was significantly higher than the nonrestored section. By the third year postrestoration, vegetation covered 50% of the restored peatland. Moss covered 90% of this vegetated area. Vegetation productivity at the restored site was also enhanced with gross ecosystem photosynthesis under full light conditions significantly higher at the restored site at both moss and herbaceous plots by 2002. While this increase in vegetation productivity provided fresh substrate and resulted in higher CO2 production potential for restored site peat, ecosystem respiration was similar to or lower than that at the nonrestored site for both bare peat and vegetated areas because of the generally wetter site conditions resulting from restoration. By upscaling chamber CO2 exchange measurements to the ecosystem level, on the basis of the relative proportion of each surface cover type, we determined the site was a net sink of ∼20 ± 5 g C m−2 during the growing season only 2 years postrestoration. Combining our results with previous work on CH4 emissions and dissolved organic carbon export, we suggest that this degraded peatland ecosystem will likely return to a net carbon sink in 6 to 10 years postrestoration.
Exploring hidden dimensions of soil fungal biodiversity: A simple technique to detect soil fungi resistant to antifungal compounds
Authors: Velho-Pereira Sonashia , Kamat Nandkumar
Published: February 2010

Soils are known to be ultimate and complex reservoirs of microbial diversity. The complex dimensions of bacterial and fungal diversity in tropical soils and microbial community dynamics are underexplored. Isolation techniques aimed at Actinomycetes generally employ highly selective media, powerful antibiotics and antifungal compounds to suppress undesirable bacteria and fungi. However some soil fungi may show their resistance towards these antifungal compounds. During our work to explore soil actinomycetes diversity, slides coated with Arginine Vitamin agar (AVA) incorporating a cocktail of antibiotics and antifungal compounds such as Nystatin, Cycloheximide, Terbinafin, Griseofulvin, and Fluconazole were exposed to soil environment and were retrieved at intervals of 4, 7, 15 and 28 days for detail microscopic studies of surface colonies. Along with actinomycetes the presence of unidentified aseptate and septate fungi was revealed indicating their resistance to combination and concentration of antifungals. Heat treatment of the soil was found to cause considerable decrease in fungal contamination probably due to elimination of heat labile fungi. Our results have led us to develop a simple procedure to sample the interesting and industrially useful strains of soil fungi resistant to common antifungal compounds. Some fungal strains are reported resistant to certain antifungals with resulting therapeutic failures as use of these antifungals inevitably selects resistant fungi, thereby pressing the urge for continuing and cyclical need of new antifungals (Augustin et al., 2004). This technique could prove useful to detect novel antifungal resistant strains with potential to emerge as novel human pathogens. It has not escaped our notice that the probability of such finding could also help to verify whether these fungi could utilize such antifungal compounds through use of hitherto undiscovered metabolic pathways and novel enzymes leading to identification of genes responsible for antifungal resistance.
Digital Image Analysis of Actinomycetes Colonies as a Potential Aid for Rapid Taxonomic Identification
Authors: Velho-Pereira Sonashia , Kamat Nandkumar
Published: February 2010

High frequency isolation of actinomycetes poses a challenge for the taxonomists hence simple and rapid identification methods are required. Our work to catalogue biodiversity of actinomycetes of Goa yielded several distinct morphotypes. After their tentative identification, the feasibility to distinguish these using digital image analyses (DIA) was explored. Digital images of wild colony morphotypes were processed using public domain SCION image analysis software. DIA revealed some intricate digital characters. A combination of these with standard morphological and microscopic characters could be potentially useful for preparing a digital identification key of the actinomycetes strains with potential application in rapid taxonomic identification.
Fundamentals of Photovoltaic Modules and Their Applications
Authors: Tiwari Gopal Nath , Dubey Swapnil
Published: February 2010

Presently there is no single publication available which covers the topics related to photovoltaic (PV) or photovoltaic thermal (PV/T) technologies, thermal modelling, CO2 mitigation and carbon trading. This book disseminates the current knowledge in the fundamentals of solar energy, photovoltaic (PV) or photovoltaic thermal (PV/T) technologies, energy security and climate change and is aimed at undergraduate and postgraduate students and professionals. The main emphasis of the book is on the design, construction, performance and application of PV and PV/T from the electricity and thermal standpoint. Hot topics covered in the book include: energy security of a nation, climate change, CO2 mitigation and carbon credit earned by using PV or PV/T technologies (Carbon Trading). This information will prove helpful in filling the gap between the researchers and professionals working on the application of photovoltaic and global climate change. It also covers economic, cost effective and sustainable aspects of photovoltaic technologies. The book gives a detailed history of the new technological developments in PV/T systems worldwide with system photographs and references and elaborates on the fundamentals of hybrid systems and their performances with thermal modelling. Energy and exergy analysis, techno-economic analysis and carbon trading are key chapters for research professionals. The book also includes important case studies to aid understanding of the subject for all readers.
Electrochemical DNA sandwich assay with a lipase label for attomole detection ofDNA
Authors: Ferapontova Elena E. , Hansen Majken N. , Saunders Aaron M. , Shipovskov Stepan , Sutherland Duncan S. , Gothelf Kurt V.
Published: February 2010

A lipase-based DNA hybridization sandwich assay was applied for monitoring attomole levels of DNA by application of the captured lipase to an ester and ferrocene-containing self-assembled monolayer leading to a decrease of the electrochemical signal.
Getting a camel through the eye of a needle: the import of folded proteins by peroxisomes
Authors: Lanyon‐Hogg Thomas , Warriner Stuart L. , Baker Alison
Published: February 2010

Peroxisomes are a family of organelles which have many unusual features. They can arise de novo from the endoplasmic reticulum by a still poorly characterized process, yet possess a unique machinery for the import of their matrix proteins. As peroxisomes lack DNA, their function, which is highly variable and dependent on developmental and/or environmental conditions, is determined by the post‐translational import of specific metabolic enzymes in folded or oligomeric states. The two classes of matrix targeting signals for peroxisomal proteins [PTS1 (peroxisomal targeting signal 1) and PTS2] are recognized by cytosolic receptors [PEX5 (peroxin 5) and PEX7 respectively] which escort their cargo proteins to, or possibly across, the peroxisome membrane. Although the membrane translocation mechanism remains unclear, it appears to be driven by thermodynamically favourable binding interactions. Recycling of the receptors from the peroxisome membrane requires ATP hydrolysis for two linked processes: ubiquitination of PEX5 (and the PEX7 co‐receptors in yeast) and the function of two peroxisome‐associated AAA (ATPase associated with various cellular activities) ATPases, which play a role in recycling or turnover of the ubiquitinated receptors. This review summarizes and integrates recent findings on peroxisome matrix protein import from yeast, plant and mammalian model systems, and discusses some of the gaps in our understanding of this remarkable protein transport system.
Formation of transient dimers by a retroviral protease
Authors: Hartl Maximilian J. , Schweimer Kristian , Reger Martin H. , Schwarzinger Stephan , Bodem Jochen , Rösch Paul , Wöhrl Birgitta M.
Published: February 2010

Retroviral proteases have been shown previously to be only active as homodimers. They are essential to form the separate and active proteins from the viral precursors. Spumaretroviruses produce separate precursors for Gag and Pol, rather than a Gag and a Gag–Pol precursor. Nevertheless, processing of Pol into a PR (protease)–RT (reverse transcriptase) and integrase is essential in order to obtain infectious viral particles. We showed recently that the PR–RT from a simian foamy virus, as well as the separate PRshort (protease) domain, exhibit proteolytic activities, although only monomeric forms could be detected. In the present study, we demonstrate that PRshort and PR–RT can be inhibited by the putative dimerization inhibitor cholic acid. Various other inhibitors, including darunavir and tipranavir, known to prevent HIV-1 PR dimerization in cells, had no effect on foamy virus protease in vitro. 1H-15N HSQC (heteronuclear single quantum coherence) NMR analysis of PRshort indicates that cholic acid binds in the proposed PRshort dimerization interface and appears to impair formation of the correct dimer. NMR analysis by paramagnetic relaxation enhancement resulted in elevated transverse relaxation rates of those amino acids predicted to participate in dimer formation. Our results suggest transient PRshort homodimers are formed under native conditions but are only present as a minor transient species, which is not detectable by traditional methods.
Reflections on studies of gene expression in aneuploids
Authors: Birchler James A.
Published: February 2010

Aneuploidy involves changes in chromosomal copy number compared with normal euploid genotypes. Studies of gene expression in aneuploids in a variety of species have claimed many different types of responses. Studies of individual genes suggest that there are both structural gene dosage effects and compensation in aneuploids, and that subtle trans-acting effects across the genome are quite prevalent. A discussion is presented concerning the normalization procedures for studying gene expression in aneuploids. A careful documentation of the modulations of gene expression in aneuploids should provide insight into the nature of cancerous cells and the basis of aneuploid syndromes.
MMP28 gene expression is regulated by Sp1 transcription factor acetylation
Authors: Swingler Tracey E. , Kevorkian Lara , Culley Kirsty L. , Illman Sara A. , Young David A. , Parker Andrew E. , Lohi Jouko , Clark Ian M.
Published: February 2010

MMP-28 (epilysin) is a recently cloned member of the MMP (matrix metalloproteinase) family. It is highly expressed in the skin by keratinocytes, the developing and regenerating nervous system and a number of other normal human tissues, as well as a number of carcinomas. The MMP28 promoter has previously been cloned and characterized identifying a conserved GT-box that binds Sp1/Sp3 (specificity proteins 1 and 3) proteins and is essential for the basal expression of the gene. The present study demonstrates that MMP28 expression is induced by HDAC (histone deacetylase) inhibitors and that this effect is mediated through the GT-box. Transient transfection assays have shown that the induction of MMP28 expression by the HDAC inhibitior TSA (trichostatin A) is mediated via Sp1 at the GT-box. Immunoprecipitation experiments have shown that the acetylation of Sp1 and Sp3 is increased by TSA treatment; however, no effect on DNA binding was observed. Histone acetyltransferases such as p300 and P/CAF [p300/CREB (cAMP-response-element-binding protein)-binding protein-associated factor] increased induction of the MMP28 promoter by Sp1. Knockdown of HDAC1 using siRNA (small interfering RNA) also induces the MMP28 promoter. Oligonucleotide pulldown identified STRAP (serine/threonine kinase receptor-associated protein) as a further protein recruited to the MMP28 promoter and acting functionally with Sp1.
Insertion of an NPVY sequence into the cytosolic domain of the erythropoietin receptor selectively affects erythropoietin-mediated signalling and function
Authors: Liron Tamar , Nahari Tal , Souroujon Miriam C. , Neumann Drorit
Published: February 2010

EPO (erythropoietin), the major hormone regulating erythropoiesis, functions via activation of its cell-surface receptor (EPO-R) present on erythroid progenitor cells. One of the most striking properties of EPO-R is its low expression on the cell surface, as opposed to its high intracellular levels. The low cell-surface expression of EPO-R may thus limit the efficacy of EPO that is routinely used to treat primary and secondary anaemia. In a recent study [Nahari, Barzilay, Hirschberg and Neumann (2008) Biochem. J. 410, 409–416] we have shown that insertion of an NPVY sequence into the intracellular domain of EPO-R increases its cell-surface expression. In the present study we demonstrate that this NPVY EPO-R insert has a selective effect on EPO-mediated downstream signalling in Ba/F3 cells expressing this receptor (NPVY-EPO-R). This is monitored by increased phosphorylation of the NPVY-EPO-R (on Tyr479), Akt, JAK2 (Janus kinase 2) and ERK1/2 (extracellular-signal-regulated kinase 1/2), but not STAT5 (signal transducer and activator of transcription 5), as compared with cells expressing wild-type EPO-R. This enhanced signalling is reflected in augmented proliferation at low EPO levels (0.05 units/ml) and protection against etoposide-induced apoptosis. Increased cell-surface levels of NPVY-EPO-R are most probably not sufficient to mediate these effects as the A234E-EPO-R mutant that is expressed at high cell-surface levels does not confer an augmented response to EPO. Taken together, we demonstrate that insertion of an NPVY sequence into the cytosolic domain of the EPO-R confers not only improved maturation, but also selectively affects EPO-mediated signalling resulting in an improved responsiveness to EPO reflected in cell proliferation and protection against apoptosis.
Frataxin, a molecule of mystery: trading stability for function in its iron-binding site
Authors: Lane Darius J. R. , Richardson Des R.
Published: February 2010

What are the structural implications for iron binding by frataxin, the mitochondrial protein whose decreased expression results in Friedreich's ataxia? Though frataxin has been shown to be essential for proper handling of iron within mitochondria (e.g. for iron–sulfur cluster and haem biosynthesis), its exact molecular function remains unclear. In this issue of the Biochemical Journal, Correia and colleagues investigate the relationship between structure and function at the putative iron-binding site of Yfh1 (yeast frataxin). Using a host of Yfh1 combination point mutants, the authors observe that the presence of a semi-conserved pocket of negative charge within the ‘acidic ridge’ region (thought to be responsible for iron binding) only mildly enhances Yfh1's ability to bind iron, though it does significantly increase the protein's structural flexibility. The general emerging view is that frataxin's keystone role in mitochondrial iron metabolism depends on iron binding. This appears to have downstream effects on protein–protein interactions that are crucial for frataxin function. The current results reveal a somewhat delicate relationship between iron binding and structural plasticity that may help unravel the enigma of frataxin's metabolic roles.
A novel EP-involved pathway for iron release from soya bean seed ferritin
Authors: Fu Xiaoping , Deng Jianjun , Yang Haixia , Masuda Taro , Goto Fumiyuki , Yoshihara Toshihiro , Zhao Guanghua
Published: February 2010

Iron in phytoferritin from legume seeds is required for seedling germination and early growth. However, the mechanism by which phytoferritin regulates its iron complement to these physiological processes remains unknown. In the present study, protein degradation is found to occur in purified SSF (soya bean seed ferritin) (consisting of H-1 and H-2 subunits) during storage, consistent with previous results that such degradation also occurs during seedling germination. In contrast, no degradation is observed with animal ferritin under identical conditions, suggesting that SSF autodegradation might be due to the EP (extension peptide) on the exterior surface of the protein, a specific domain found only in phytoferritin. Indeed, EP-deleted SSF becomes stable, confirming the above hypothesis. Further support comes from a protease activity assay showing that EP-1 (corresponding to the EP of the H-1 subunit) exhibits significant serine protease-like activity, whereas the activity of EP-2 (corresponding to the EP of the H-2 subunit) is much weaker. Consistent with the observation above, rH-1 (recombinant H-1 ferritin) is prone to degradation, whereas its analogue, rH-2, becomes very stable under identical conditions. This demonstrates that SSF degradation mainly originates from the serine protease-like activity of EP-1. Associated with EP degradation is a considerable increase in the rate of iron release from SSF induced by ascorbate in the amyloplast (pH range, 5.8–6.1). Thus phytoferritin may have facilitated the evolution of the specific domain to control its iron complement in response to cell iron need in the seedling stage.
Electrostatic interactions play a minor role in the binding of ExoS to 14-3-3 proteins
Authors: Yasmin Lubna , Veesenmeyer Jeffrey L. , Diaz Maureen H. , Francis Matthew S. , Ottmann Christian , Palmer Ruth H. , Hauser Alan R. , Hallberg Bengt
Published: February 2010

14-3-3 proteins belong to a family of conserved molecules expressed in all eukaryotic cells that play an important role in a multitude of signalling pathways. 14-3-3 proteins bind either to phosphoserine/phosphothreonine residues or to sequence-specific non-phosphorylated motifs in more than 200 interaction partners [Pozuelo Rubio, Geraghty, Wong, Wood, Campbell, Morrice and Mackintosh (2004) Biochem. J. 379, 395–408]. These interactions result in cell-cycle regulation, apoptosis, stress responses, cell metabolism and malignant transformation. One example of a phosphorylation-independent interaction is the binding of 14-3-3 to ExoS (exoenzyme S), a bacterial ADP-ribosyltransferase toxin of Pseudomonas aeruginosa. In the present study, we have utilized additional biochemical and infection analyses to define further the structural basis of the interaction between ExoS and 14-3-3. An ExoS leucine-substitution mutant dramatically reduced the interaction potential with 14-3-3 suggesting that Leu422, Leu423, Leu426 and Leu428 of ExoS are important for its interaction with 14-3-3, its enzymatic activity and cytotoxicity. However, ExoS substitution mutants of residues that interact with 14-3-3 through an electrostatic interaction, such as Ser416, His418, Asp424 and Asp427, showed no reduction in their interaction potential with 14-3-3. These ExoS substitution mutants were also as aggressive as wild-type ExoS at inducing cell death and to modify endogenous ExoS target within the cell. In conclusion, electrostatic interaction between ExoS and 14-3-3 via polar residues (Ser416, His418, Asp424 and Asp427) appears to be of secondary importance. Thus the interaction between the ‘roof’ of the groove of 14-3-3 and ExoS relies more on hydrophobic interaction forces, which probably contributes to induce cell death after ExoS infection and activation.
Functional characterization of polypeptide release factor 1b in the ciliate Euplotes
Authors: Wang Yan , Chai Baofeng , Wang Wei , Liang Aihua
Published: February 2010

In higher eukaryotes, RF-I (class I release factor) [eRF1 (eukaryotic release factor 1)] is responsible for stop codon recognition and promotes nascent polypeptide release from the ribosome. Interestingly, two class I RFs, eRF1a and eRF1b, have been identified among the ciliates Euplotes, which are variant code organisms. In the present study, we analysed the comparative expression of eRF1a and eRF1b in Euplotes cells, demonstrating that the expression of eRF1b was higher than that of eRF1a. An interaction between eRF1b and eRF3 was confirmed, suggesting that an eRF1b function is facilitated by eRF3. Co-localization of both eRF1s indicated that they function in the same subcellular location in Euplotes cells. We also analysed the characteristics of stop codon discrimination by eRF1b. Like eRF1a, eRF1b recognized UAA and UAG as stop codons, but not UGA. This finding disagreed with the deduced characteristics of eRF1a/eRF1b from the classic hypothesis of ‘anticodon-mimicry’ proposed by Muramatsu et al. [Muramatsu, Heckmann, Kitanaka and Kuchino (2001) FEBS Lett. 488, 105–109]. Mutagenesis experiments indicated that the absolutely conserved amino acid motif ‘G31T32’ (numbered as for human eRF1) in eRF1b was the key to efficient stop codon recognition by eRF1b. In conclusion, these findings support and improve the ‘cavity model’ of stop codon discrimination by eRF1 proposed by Bertram et al. [Bertram, Bell, Ritchie, Fullerton and Stansfield (2000) RNA 6, 1236–1247] and Inagaki et al. [Inagaki, Blouin, Doolittle and Roger (2002) Nucleic Acids Res. 30, 532–544].
Electron capture dissociation mass spectrometric analysis of lysine-phosphorylated peptides
Authors: Kowalewska Karolina , Stefanowicz Piotr , Ruman Tomasz , Frączyk Tomasz , Rode Wojciech , Szewczuk Zbigniew
Published: February 2010

Phosphorylation of proteins is an essential signalling mechanism in eukaryotic and prokaryotic cells. Although N-phosphorylation of basic amino acid is known for its importance in biological systems, it is still poorly explored in terms of products and mechanisms. In the present study, two MS fragmentation methods, ECD (electron-capture dissociation) and CID (collision-induced dissociation), were tested as tools for analysis of N-phosphorylation of three model peptides, RKRSRAE, RKRARKE and PLSRTLSVAAKK. The peptides were phosphorylated by reaction with monopotassium phosphoramidate. The results were confirmed by 1H NMR and 31P NMR studies. The ECD method was found useful for the localization of phosphorylation sites in unstable lysine-phosphorylated peptides. Its main advantage is a significant reduction of the neutral losses related to the phosphoramidate moiety. Moreover, the results indicate that the ECD–MS may be useful for analysis of regioselectivity of the N-phosphorylation reaction. Stabilities of the obtained lysine-phosphorylated peptides under various conditions were also tested.
Phosphorylation states of STAT3 and ERKs in mouse embryonic stem cells
Authors: Miyazu Sakiko , Furuno Tadahide , Nakanishi Mamoru
Published: February 2010

Mouse ES (embryonic stem) cells are maintained in an undifferentiated state in the presence of LIF (leukaemia‐inhibitory factor). In general, LIF engages a heterodimeric receptor complex composed of a low‐affinity LIF receptor (LIFRβ) and gp130, and activates STAT3 (signal transducers and activators of transcription 3) and ERKs (extracellular signal‐regulated kinases). However, in undifferentiated ES cells in the presence of LIF, STAT3 is phosphorylated but ERKs are not. The removal of LIF‐induced dephosphorylation of phospho‐STAT3 and phosphorylation of ERKs resulted in the differentiation of ES cells. Here, we show that the dephosphorylation of phospho‐STAT3 corresponds to the activation of ERKs pathway from the time‐courses of the phosphorylation levels in detail. We found that the treatment of membrane‐permeable STAT3IP (STAT3 inhibitory peptide), which inhibits homodimeric formation of STAT3, induced the phosphorylation of ERKs in ES cells in the presence of LIF. In addition, the removal of LIF decreased the expression level of SOCS3 (suppressor of cytokine signalling 3), a negative regulator of LIF signalling, and the phosphorylation of ERKs was efficiently induced in the ES cells where SOCS3 was down‐regulated. These results suggested that LIF‐induced SOCS3 suppressed the ERKs activation pathway in undifferentiated ES cells, and the down‐regulation of SOCS3 by the removal of LIF triggered the phosphorylation of ERKs.
Application of InGaAs/GaAs superlattice-base structure for InGaP/GaAs superlattice-emitter bipolar transistor
Authors: Tsai Jung-Hui , Lee Yuan-Hong , Dale Ning-Feng , Sheng Jhih-Syuan , Ma Yung-Chun , Ye Sheng-Shiun
Published: February 2010

The performance of an InGaP/GaAs superlattice-emitter bipolar transistor with InGaAs/GaAs superlattice-base structure is demonstrated by experimental results. The injecting electrons from superlattice emitter are easy to transport into the superlattice-base region for promoting the collector current by tunneling behavior. Furthermore, the average energy gap of base regime is substantially reduced by the use of InGaAs/GaAs superlattice structure for the requirement of low turn-on voltage. Experimentally, the transistor exhibits a maximum common-emitter current gain of 295 and a relatively low collector-emitter offset voltage of only 16 mV. In particular, the ideality factor of collector current near to unity is obtained.
Dynamic measurement and modeling of the Casimir force at the nanometer scale
Authors: Kohoutek John , Wan Ivy Yoke Leng , Mohseni Hooman
Published: February 2010

We present a dynamic method for measurement of the Casimir force with an atomic force microscope (AFM) with a conventional AFM tip. With this method, originally based on the phase of vibration of the AFM tip, we are able to verify the Casimir force at distances of nearly 6 nm with an AFM tip that has a radius of curvature of nearly 100 nm. Until now dynamic methods have been done using large metal spheres at greater distances. Also presented is a theoretical model based on the harmonic oscillator, including nonidealities. This model accurately predicts the experimental data.
Observation of the large orbital entropy in Zn-doped orbital-spin-coupled system MnV2O4
Authors: Luo X. , Sun Y. P. , Lu W. J. , Zhu X. B. , Yang Z. R. , Song W. H.
Published: February 2010

We present the investigation on the magnetocaloric effect (MCE) in an orbital-spin-coupled spinel vanadate Mn0.95Zn0.05V2O4 via the dc magnetization and the specific-heat measurements. The maximum values of magnetic entropy change of Mn0.95Zn0.05V2O4 reach 9.6 and 16.5 J/kg K for field change 0–4 T around ferrimagnetic ordering temperature TC=52.5 K and orbital ordering temperature TOO=45 K. Except for a small quantity of contribution of the spin entropy, the observed giant MCE around TOO may be attributed to the orbital entropy due to the change of the orbital state of V3+.
Integrated terahertz pulse generation and amplification in quantum cascade lasers
Authors: Dhillon S. S. , Sawallich S. , Jukam N. , Oustinov D. , Madéo J. , Barbieri S. , Filloux P. , Sirtori C. , Marcadet X. , Tignon J.
Published: February 2010

Integrated terahertz (THz) pulse generation and amplification in a THz quantum cascade laser (QCL) is demonstrated. Intracavity THz pulses are generated by exciting the facet of the QCL with an ultrafast Ti:Sapphire laser (∼100 fs) and detected using electro-optic sampling. Maximum THz field emission is found with an interband transition of 1.535 eV (809 nm) and by narrowing the excitation laser bandwidth to ∼3 THz. These resonance conditions correspond to the narrowband excitation of the quantum cascade miniband, indicating that the THz pulse is generated by the photoexcited carriers that are accelerated by the applied field. The generated pulse is subsequently amplified by the narrowband gain of the laser as it propagates through the QCL cavity.
Single step, complementary doping of graphene
Authors: Brenner Kevin , Murali Raghunath
Published: February 2010

A single-step doping method capable of high resolution n- and p-type doping of large area graphene is presented. Thin films of hydrogen silsesquoxane on exfoliated graphene are used to demonstrate both electron and hole doping through control of the polymer cross-linking process. This dual-doping is attributed to the mismatch in bond strength of the Si–H and Si–O bonds in the film as well as out-gassing of hydrogen with increasing cross-linking. A high-resolution graphene p-n junction is demonstrated using this method.
Monte Carlo modeling of the fiber curliness effect on percolation of conductive composites
Authors: Ma H. M. , Gao X.-L. , Tolle T. Benson
Published: February 2010

A three-dimensional (3D) Monte Carlo model is developed to study the fiber curliness effect on the percolation threshold of a composite filled with electrically conductive curved fibers. These fibers are simulated as zigzag-shaped fibers that are randomly positioned in the composite, forming a 3D random network. The simulation results show that the fiber curliness can significantly affect the percolation threshold: the more curved the fibers, the higher the threshold. The results also reveal an exponential relationship between the threshold and the fiber aspect ratio: the higher the aspect ratio, the lower the threshold. These predicted trends agree well with existing experimental and simulation results based on straight fibers or curved fibers with simpler shapes.
Low-dimensional Mott material: Transport in ultrathin epitaxial LaNiO3 films
Authors: Son Junwoo , Moetakef Pouya , LeBeau James M. , Ouellette Daniel , Balents Leon , Allen S. James , Stemmer Susanne
Published: February 2010

Electrical resistivity and magnetotransport are explored for thin (3–30 nm), epitaxial LaNiO3 films. Films were grown on three different substrates to obtain LaNiO3 films that are coherently strained, with different signs and magnitude of film strain. It is shown that d-band transport is inhibited as the layers progress from compression to tension. The Hall coefficient is “holelike.” Increasing tensile strain causes the film resistivity to increase, causing strong localization to appear below a critical thickness.
Anisotropic-strain-induced antiferromagnetic-insulating state with strong phase instability in epitaxial (La0.8Pr0.2)0.67Ca0.33MnO3 films
Authors: Zhang F. H. , Huang Z. , Gao G. Y. , Chen P. F. , Wang L. F. , Tan X. L. , Wu W. B.
Published: February 2010

We grow epitaxial (La0.8Pr0.2)0.67Ca0.33MnO3 films simultaneously on the lattice-closely-matched substrates, cubic (LaAlO3)0.3(Sr2AlTaO6)0.7 [LSAT(001)] and orthorhombic NdGaO3 [NGO(001) and NGO(110)]. While all as-grown films show a ferromagnetic-metallic (FM) ground state as observed for the bulk target, the annealed films show quite different magnetotransport behavior as follows: on NGO(110) they show a robust FM ground state, on LSAT(001) and NGO(001) however, they show surprisingly a coexisted antiferromagnetic insulating state with high phase instability in a wide temperature range. The phase coexistence being easily induced via the control of anisotropic epitaxial strain suggests that the phase separation in manganites could be elastically driven, and thus can be strain-engineered for devices applications.
Exploring the Sensitivity of Jobs — Housing Statistics to Imperfect Travel Time Information
Authors: Horner Mark W
Published: February 2010

Increasingly, researchers have discussed ways of utilizing excess commuting/jobs — housing methodologies in policy analyses. One potential barrier involves the uncertainty associated with using network-based travel time estimates in the commute models. This paper examines the extent to which various excess commuting/jobs — housing statistics are sensitive to changes in their input transportation costs. A series of computational experiments are run using spatial data from a smaller metropolitan area. Results reveal the variability in the commuting estimates given assumptions about likely travel time variability.
Representing Human Hands Haptically or Visually from First-Person versus Third-Person Perspectives
Authors: Kitada Ryo , Dijkerman H Chris , Soo Grace , Lederman Susan J
Published: February 2010

Humans can recognise human body parts haptically as well as visually. We employed a mental-rotation task to determine whether participants could adopt a third-person perspective when judging the laterality of life-like human hands. Female participants adopted either a first-person or a third-person perspective using vision (experiment 1) or haptics (experiment 2), with hands presented at various orientations within a horizontal plane. In the first-person perspective task, most participants responded more slowly as hand orientation increasingly deviated from the participant's upright orientation, regardless of modality. In the visual third-person perspective task, most participants responded more slowly as hand orientation increasingly deviated from the experimenter's upright orientation; in contrast, less than half of the participants produced this same inverted U-shaped response-time function haptically. In experiment 3, participants were explicitly instructed to adopt a third-person perspective haptically by mentally rotating the rubber hand to the experimenter's upright orientation. Most participants produced an inverted U-shaped function. Collectively, these results suggest that humans can accurately assume a third-person perspective when hands are explored haptically or visually. With less explicit instructions, however, the canonical orientation for hand representation may be more strongly influenced haptically than visually by body-based heuristics, and less easily modified by perspective instructions.
Effect of microwave treatment on lucerne fodder
Authors: Brodie Graham , Rath Craig , Devanny Merita , Reeve Jessica , Lancaster Carmel , Harris Gerry , Chaplin Sarah , Laird Chris
Published: February 2010

Preliminary research has suggested that in vitro dry matter disappearance of some poor-quality fodder materials can be improved by microwave treatment. A laboratory-scale experiment that treated 50-g samples of lucerne hay in a 750-W microwave oven for 0, 40 and 80 s revealed that dry matter percentage increased by 1.7% as microwave treatment time increased from 0 to 80 s. The in vitro dry matter disappearance increased by 14.9% as microwave treatment increased from 0 to 80 s; however, there was no significant change in crude protein due to excessive variability in the results. This experiment was followed up with a larger-sample experiment in which 25-kg bags of lucerne fodder were treated for 7.5, 15, 22.5 or 30 min in an experimental 6-kW microwave chamber. Dry matter percentage increased by 7.2% as microwave treatment time increased from 0 to 30 min. Microwave treatment significantly increased dry matter disappearance during the in vitro digestion study; however, there were no significant differences between the various microwave treatment times. The 15-min treatment resulted in the greatest increase in dry matter disappearance (5.9%). The crude protein retained in the digestion residues increased by 19.2% as microwave treatment increased from 0 to 30 min. These laboratory studies were followed up with an animal response study in which 22 12–14-month-old Merino wethers were randomly allocated into either a group receiving a maintenance ration of untreated lucerne or a group receiving the same weight of microwave-treated lucerne. The average weight of the control group fluctuated around their starting weight during the 5-week-long trial, as would be expected from feeding a maintenance ration. By the end of the trial their average weight was 0.4% higher than when they started. However the group being fed the microwave-treated lucerne gained 8.1% of their initial bodyweight by the end of the trial.
Influence of stocking rate and mixed grazing of Angora goats and Merino sheep on animal and pasture production in southern Australia. 1. Botanical composition, sward characteristics and availability of components of annual temperate pastures
Authors: McGregor B. A.
Published: February 2010

The effects of animal species (AS; Angora goats, Merino sheep or goats and sheep mixed grazed together at ratio 1 : 1) and stocking rate (SR; 7.5, 10 and 12.5 animals/ha) on the availability, botanical composition and sward characteristics of annual temperate pastures under continuous grazing were determined in a replicated experiment from 1981 to 1984. AS and SR had significant effects on pasture availability and composition and many AS × SR interactions were detected. The pastures grazed by sheep had significantly reduced content and proportion of subterranean clover and more undesirable grasses compared with those grazed by goats. There were no differences in dry matter availabilities between goat- and sheep-grazed pastures at 7.5/ha, but at 10 and 12.5/ha goat pastures had significantly increased availabilities of green grass, dead and green clover and less weeds compared with sheep pastures. There was a significant AS × SR interaction for the density of seedlings in May following pasture germination. Between July and January, the height of pastures was greater under goats than sheep but from January to March pasture height declined more on goat-grazed than on sheep-grazed pastures. There was an AS × SR interaction for incidence of bare ground. Increasing the SR increased bare ground in pastures grazed by sheep but no change occurred on pastures grazed by goats. Changes in pasture characteristics due to increased SR were minimised on pastures grazed by goats but the grazing of sheep caused larger and faster changes and the pastures were damaged at the highest SR. Goats did not always select the same herbage material as sheep, changed their selection between seasons and were not less selective than sheep. Angora goats were flexible grazers and continually adapted their grazing behaviour to changing herbage conditions. Goat grazing led to an increase in subterranean clover, an accumulation of dead herbage at the base of the sward, reduced bare ground, taller pastures in spring and a more stable botanical composition. Mixed-grazed pasture characteristics were altered with SR. With careful management Angora goats on sheep farms may be used to manipulate pasture composition, to speed up establishment of subterranean clover, to decrease soil erosion and to reduce weed invasion.
Fitness flux and ubiquity of adaptive evolution
Authors: Mustonen Ville , Lässig Michael
Published: February 2010

Natural selection favors fitter variants in a population, but actual evolutionary processes may decrease fitness by mutations and genetic drift. How is the stochastic evolution of molecular biological systems shaped by natural selection? Here, we derive a theorem on the fitness flux in a population, defined as the selective effect of its genotype frequency changes. The fitness-flux theorem generalizes Fisher’s fundamental theorem of natural selection to evolutionary processes including mutations, genetic drift, and time-dependent selection. It shows that a generic state of populations is adaptive evolution: there is a positive fitness flux resulting from a surplus of beneficial over deleterious changes. In particular, stationary nonequilibrium evolution processes are predicted to be adaptive. Under specific nonstationary conditions, notably during a decrease in population size, the average fitness flux can become negative. We show that these predictions are in accordance with experiments in bacteria and bacteriophages and with genomic data in Drosophila. Our analysis establishes fitness flux as a universal measure of adaptation in molecular evolution.
Abnormal development of the cerebral cortex and cerebellum in the setting of lamin B2 deficiency
Authors: Coffinier Catherine , Chang Sandy Y. , Nobumori Chika , Tu Yiping , Farber Emily A. , Toth Julia I. , Fong Loren G. , Young Stephen G.
Published: February 2010

Nuclear lamins are components of the nuclear lamina, a structural scaffolding for the cell nucleus. Defects in lamins A and C cause an array of human diseases, including muscular dystrophy, lipodystrophy, and progeria, but no diseases have been linked to the loss of lamins B1 or B2. To explore the functional relevance of lamin B2, we generated lamin B2-deficient mice and found that they have severe brain abnormalities resembling lissencephaly, with abnormal layering of neurons in the cerebral cortex and cerebellum. This neuronal layering abnormality is due to defective neuronal migration, a process that is dependent on the organized movement of the nucleus within the cell. These studies establish an essential function for lamin B2 in neuronal migration and brain development.
Only two amino acids are essential for cytolytic toxin recognition of cholesterol at the membrane surface
Authors: Farrand Allison J. , LaChapelle Stephanie , Hotze Eileen M. , Johnson Arthur E. , Tweten Rodney K.
Published: February 2010

The recognition and binding of cholesterol is an important feature of many eukaryotic, viral, and prokaryotic proteins, but the molecular details of such interactions are understood only for a few proteins. The pore-forming cholesterol-dependent cytolysins (CDCs) contribute to the pathogenic mechanisms of a large number of Gram-positive bacteria. Cholesterol dependence of the CDC mechanism is a hallmark of these toxins, yet the identity of the CDC cholesterol recognition motif has remained elusive. A detailed analysis of membrane interactive structures at the tip of perfringolysin O (PFO) domain 4 reveals that a threonine-leucine pair mediates CDC recognition of and binding to membrane cholesterol. This motif is conserved in all known CDCs and conservative changes in its sequence or order are not well tolerated. Thus, the Thr-Leu pair constitutes a common structural basis for mediating CDC-cholesterol recognition and binding, and defines a unique paradigm for membrane cholesterol recognition by surface-binding proteins.
Forebrain overexpression of CK1δ leads to down-regulation of dopamine receptors and altered locomotor activity reminiscent of ADHD
Authors: Zhou Mingming , Rebholz Heike , Brocia Christine , Warner-Schmidt Jennifer L. , Fienberg Allen A. , Nairn Angus C. , Greengard Paul , Flajolet Marc
Published: February 2010

Dopamine neurotransmission controls motor and perseverative behavior, is mediated by protein phosphorylation, and may be perturbed in disorders of attention and hyperactivity. To assess the role of casein kinase I (CK1) in the regulation of dopamine signaling, we generated a genetically modified mouse line that overexpresses CK1δ (CK1δ OE) specifically in the forebrain. Overexpression was confirmed both at the mRNA and at the protein levels. Under basal conditions, CK1δ OE mice exhibited horizontal and vertical hyperactivity, reduced anxiety, and nesting behavior deficiencies. The CK1δ OE mice also presented paradoxical responses to dopamine receptor stimulation, showing hypoactivity following injection of d-amphetamine or methylphenidate, indicating that CK1 activity has a profound effect on dopamine signaling in vivo. Interestingly, CK1δ overexpression led to significantly reduced D1R and D2R dopamine receptor levels. All together, under basal conditions and in response to drug stimulation, the behavioral phenotype of CK1δ OE mice is reminiscent of the symptoms and drug responses observed in attention-deficit/hyperactivity disorder and therefore the CK1δ OE mice appear to be a model for this disorder.
Natural variation for seed dormancy in Arabidopsis is regulated by additive genetic and molecular pathways
Authors: Bentsink Leónie , Hanson Johannes , Hanhart Corrie J. , Blankestijn-de Vries Hetty , Coltrane Colin , Keizer Paul , El-Lithy Mohamed , Alonso-Blanco Carlos , de Andrés M. Teresa , Reymond Matthieu , van Eeuwijk Fred , Smeekens Sjef , Koornneef Maarten
Published: February 2010

Timing of germination is presumably under strong natural selection as it determines the environmental conditions in which a plant germinates and initiates its postembryonic life cycle. To investigate how seed dormancy is controlled, quantitative trait loci (QTL) analyses has been performed in six
Arabidopsis thaliana
recombinant inbred line populations by analyzing them simultaneously using a mixed model QTL approach. The recombinant inbred line populations were derived from crosses between the reference accession Landsberg
erecta
(L
er
) and accessions from different world regions. In total, 11
delay of germination
(
DOG
) QTL have been identified, and nine of them have been confirmed by near isogenic lines (NILs). The absence of strong epistatic interactions between the different
DOG
loci suggests that they affect dormancy mainly by distinct genetic pathways. This was confirmed by analyzing the transcriptome of freshly harvested dry seeds of five different
DOG
NILs. All five
DOG
NILs showed discernible and different expression patterns compared with the expression of their genetic background L
er.
The genes identified in the different
DOG
NILs represent largely different gene ontology profiles. It is proposed that natural variation for seed dormancy in Arabidopsis is mainly controlled by different additive genetic and molecular pathways rather than epistatic interactions, indicating the involvement of several independent pathways.
Large reversible electric-voltage manipulation of magnetism in NiFe/BaTiO3 heterostructures at room temperature
Authors: Zhang Yi , Liu Jing , Xiao X H , Peng T C , Jiang C Z , Lin Y H , Nan C W
Published: February 2010

NiFe/BaTiO3 heterostructures were grown on (0 0 1)-SrTiO3 single crystal substrates with SrRuO3 as a buffer layer via pulsed laser deposition and off-axis magnetron sputtering. The magneto-optical Kerr effect measurement on the heterostructures demonstrated that the magnetism of the NiFe thin film can be reversibly manipulated by switching the electric voltage applied on the BaTiO3 layer, with a large change in the magnetic coercive field and saturation magnetization of the NiFe thin films. An analogous on–off switch of magnetism in the NiFe thin films was demonstrated and a novel way for Curie point writing based on the heterostructure was also proposed. Our results may provide a useful way for manipulating magnetism of bits in high-density information storage with better thermal performance and reduced power consumption.