bluuebunny/crossref_metadata_2025 huggingface dataset:
Thermal stability of high frequency properties of gradient-composition-sputtered FeCoHf films with and without stripe domains
Authors: Phuoc Nguyen N. , Ong C. K.
Published: July 2013

A systematic study on the thickness dependence of dynamic magnetic properties and their thermal stability behaviors of FeCoHf thin films grown by gradient-composition sputtering technique was carried out. The critical thickness for the formation of stripe domain structures at room temperature was found to be around 120 nm based on the appearance of the multiple resonance peaks and the shape of the magnetization curves. For the films with thicknesses less than 90 nm, the ferromagnetic resonance frequency and in-plane magnetic anisotropy are increased with the increasing of temperature; however, for the films with thicknesses in the range from 90 nm to 120 nm, the ferromagnetic resonance frequency is reduced with temperature and the secondary peak appears as the temperature is raised suggesting an evolution of stripe domains. For the films with stripe domains at room temperature, the ferromagnetic resonance frequency is also decreased with increasing temperature, and in some cases, there is a splitting up of the resonance peaks indicating that there is a change in the stripe domain states when the sample is heated up. All the results are discussed considering the contribution of stress-induced magnetic anisotropy and the increasing of a weak perpendicular magnetic anisotropy.
Defect states in hybrid solar cells consisting of Sb2S3 quantum dots and TiO2 nanoparticles
Authors: Lee Dong Uk , Woo Pak Sang , Gook Cho Seong , Kyu Kim Eun , Il Seok Sang
Published: July 2013

We have studied defect states in an organic-inorganic hybrid solar cell containing Sb2S3 quantum dots (QDs) and TiO2 nanoparticles (NPs) by using deep level transient spectroscopy (DLTS). An Au electrode was deposited as a Schottky contact on the sample, where the Sb2S3 QDs were distributed on the surface of TiO2 NPs by chemical synthesis. The activation energy and capture-cross section of an interface state between the Sb2S3 QDs and the TiO2 NPs were found to be about 0.78 eV and 2.21 × 10−9 cm−2, respectively. Also, the densities of this interface trap under a measurement voltage of −1 V were approximately 2.5 × 1017 cm−3. Based on these results, the interface trap was positioned around Ec − 1.03 eV below the conduction band edge of Sb2S3 QD. Thus, the external quantum efficiency of the solar cell was affected because of its role as a recombination center for carriers generated from Sb2S3 QDs.
Unipolar vertical transport in GaN/AlGaN/GaN heterostructures
Authors: Nath D. N. , Yang Z. C. , Lee C.-Y. , Park P. S. , Wu Y.-R. , Rajan S.
Published: July 2013

In this letter, we report on unipolar vertical transport characteristics in c-plane GaN/AlGaN/GaN heterostructures. Vertical current in heterostructures with random alloy barriers was found to be independent of dislocation density and heterostructure barrier height. Percolation-based transport due to random alloy fluctuations in the ternary AlGaN is suggested as the dominant transport mechanism. This hypothesis is supported by simulations using drift-diffusion transport model incorporating statistical fluctuations of Al-composition and confirmed through experiments showing that non-random or digital AlGaN alloys and polarization-engineered binary GaN barriers can eliminate percolation transport and reduce leakage significantly. The understanding of vertical transport and methods for effective control proposed here will greatly impact III-nitride unipolar vertical devices.
Improvement of photocurrent generation of Ag2S sensitized solar cell through co-sensitization with CdS
Authors: Hwang Insung , Seol Minsu , Kim Heejin , Yong Kijung
Published: July 2013

In this study, photovoltaic application of Ag2S-CdS heterostructure is reported. The photovoltaic cell generated considerably high photocurrent density (Jsc) of 27.6 mA/cm2, which is over two times larger than that of the Ag2S quantum dot sensitized solar cell (QDSSC) of 11.3 mA/cm2. This improvement is due to the cascade-shaped band structure alignment of ZnO/CdS/Ag2S and to the excellent role of CdS as a buffer layer for relieving lattice mismatch. The power conversion efficiency of the CdS/Ag2S QDSSC, which was attributed to the superior Jsc, was 2.4%, twice as high as the 1.2% efficiency of the Ag2S QDSSC and the CdS QDSSC.
Reproductive performance in the Sheep CRC Information Nucleus using artificial insemination across different sheep-production environments in southern Australia
Authors: Geenty K. G. , Brien F. D. , Hinch G. N. , Dobos R. C. , Refshauge G. , McCaskill M. , Ball A. J. , Behrendt R. , Gore K. P. , Savage D. B. , Harden S. , Hocking-Edwards J. E. , Hart K. , van der Werf J. H. J.
Published: July 2013

The present paper covers reproductive performance in an artificial-insemination (AI) program of the Sheep CRC Information Nucleus with 24 699 lambs born at eight locations in southern Australia across five lambings between 2007 and 2011. Results from AI with frozen semen compared well with industry standards for natural mating. Conception rates averaged 72%, and 1.45 lambs were born per ewe pregnant for Merino ewes and 1.67 for crossbreds. Lamb deaths averaged 21% for Merino ewes and 15% for crossbreds and 19%, 22% and 20% for lambs from ewes that were mated to terminal, Merino and maternal sire types, respectively. Net reproductive rates were 82% for Merino ewes and 102% for crossbreds. From 3198 necropsies across 4 years, dystocia and starvation-mismothering accounted for 72% of lamb deaths within 5 days of lambing. Major risk factors for lamb mortality were birth type (single, twin or higher order), birthweight and dam breed. Losses were higher for twin and triplet lambs than for singles and there was greater mortality at relatively lighter and heavier birthweights. We conclude that reproductive rate in this AI program compared favourably with natural mating. Lamb birthweight for optimum survival was in the 4–8-kg range. Crossbred ewes had greater reproductive efficiency than did Merinos.
Leucocyte profiles and body condition in breeding brown boobies and red-tailed tropicbirds: effects of breeding stage and sex
Authors: Dehnhard Nina , Hennicke Janos C.
Published: July 2013

Foraging in a habitat with highly unpredictable availability of prey, breeding seabirds have to balance their investment in reproduction with their own energetic requirements, including their immune system. This study aimed to investigate the influence of breeding stage (incubation and chick rearing) and sex on body condition and leucocyte profiles in two sympatrically breeding tropical seabird species on Christmas Island, Indian Ocean: the strongly size-dimorphic, inshore-foraging brown booby (Sula leucogaster) and the monomorphic offshore-foraging red-tailed tropicbird (Phaethon rubricauda). Brown booby males were in poorer body condition than females. Male brown boobies had a higher heterophil/lymphocyte (H/L) ratio (indicating higher stress levels), and higher eosinophil numbers (suggesting higher intestinal parasite loads) than females, and sex differences in H/L ratio and body condition were more pronounced during chick rearing. The results suggest that in brown boobies, incubation was energetically less demanding for males than chick rearing, but that the smaller males were energetically more challenged than females during both breeding stages. In the monomorphic red-tailed tropicbird, there were no differences in body condition between sexes and breeding stage, and there was no influence of sex or breeding stage on the leucocyte profiles. The results suggest that incubation and chick rearing are equally demanding for males and females, and that the increased energetic demands of chick rearing are likely to be buffered by a bimodal foraging strategy by both sexes. Our results show that breeding stage as well as sex- and species-specific foraging behaviour can affect leucocyte profiles and particularly the H/L ratio differentially in sympatrically breeding seabird species.
Movement and mortality of Murray cod, Maccullochella peelii, during overbank flows in the lower River Murray, Australia
Authors: Leigh Sandra J. , Zampatti Brenton P.
Published: July 2013

Conservation of Murray cod (Maccullochella peelii), a large endangered fish species of Australia’s Murray–Darling Basin, relies on a detailed understanding of life history, including movement patterns and habitat use. We used radio-tracking to investigate the movement of 36 Murray cod in main channel and anabranch habitats of the lower River Murray during a flood and associated hypoxic blackwater event. During a flood peak of ~93 000 ML day–1, dissolved oxygen decreased to 1.2 mg L–1. Four movement types were observed: (1) localised small-scale movement, (2) broad-scale movement within anabranch habitats, (3) movement between anabranch and main channel habitats, and (4) large-scale riverine movement. Murray cod exhibited high fidelity to anabranch habitats but also moved extensively between anabranches and the main channel. Fish were consistently located in the main channel or permanent anabranches, suggesting that use of ephemeral floodplain habitats is limited, and highlighting the importance of connectivity between off-channel and main channel habitats. Mortality of radio-tagged fish was considerable (25%) in association with low dissolved oxygen concentrations, indicating that hypoxic blackwater may have had a substantial impact on Murray cod populations in the lower River Murray.
Diversity of Fish-Associated Flavobacteria of Michigan
Authors: Loch T. P. , Fujimoto M. , Woodiga S. A. , Walker E. D. , Marsh T. L. , Faisal M.
Published: July 2013

Flavobacteriosis poses a serious threat to wild and propagated fish stocks alike, accounting for more fish mortality in Michigan and its associated state fish hatcheries than all other pathogens combined. Although this consortium of fish diseases has primarily been attributed to Flavobacterium psychrophilum, F. columnare, and F. branchiophilum, herein we describe a diverse assemblage of Flavobacterium and Chryseobacterium spp. isolates recovered from diseased as well as apparently healthy wild, feral, and farmed fish of Michigan. Among 254 fish-associated flavobacterial isolates recovered from 21 fish species during 2003–2010, 211 were identified as Flavobacterium spp., whereas 43 were identified as Chryseobacterium spp. according to ribosomal RNA partial gene sequencing and phylogenetic analysis. Although F. psychrophilum and F. columnare were indeed associated with multiple fish mortality events, many previously uncharacterized flavobacteria were recovered from systemically infected fish showing overt signs of disease, and in vitro protease assays demonstrated that these isolates were highly proteolytic to multiple substrates that comprise host tissues. Indeed, the majority of the isolates either (1) were most similar to recently described fish-associated Flavobacterium and Chryseobacterium spp. that have never before been reported in North America (e.g., F. oncorhynchi, F. araucananum, C. viscerum, C. piscicola, and C. chaponense) or (2) did not cluster with any described species and most likely represent novel flavobacterial taxa. This study highlights the extreme diversity of flavobacteria that are potentially associated with flavobacteriosis in Michigan.

Received September 13, 2012; accepted December 6, 2012
Growth and Survival of Juvenile Gulf Killifish Fundulus grandis in Recirculating Aquaculture Systems
Authors: Ofori-Mensah Samuel , Green Christopher C , Nunoo Francis K E
Published: July 2013

Gulf Killifish Fundulus grandis is one of the largest killifish species. It is a euryhaline teleost and a popular baitfish occurring along the coastal Gulf of Mexico and southern Atlantic states. There is currently limited information on the grow-out characteristics of killifish in indoor recirculating aquaculture systems (RAS). This preliminary study aims at determining the effects of stocking density on the growth and survival of juvenile Gulf Killifish in indoor RAS. Individuals of 0.45 ± 0.01 g (mean ± SE) weight were stocked at initial densities of 2 and 5 fish/L in 60-L tanks in RAS with four replicates each. After 82 d of culture, difference in growth at these densities was not significant (P > 0.629). Mean survival and gross and net yields differed by stocking density. Survival (94.6%) in the lowest density was significantly high (ANOVA: P < 0.01) compared with survival (83.9%) in the highest density. Gross and net yields were significantly high (ANOVA: P < 0.01) at the 5 fish/L stocking densities. Compared with the traditional pond system, the use of RAS in this preliminary study enabled stocking of killifish at very high densities. However, cultured fish grew relatively slow in RAS compared with pond culture and did not reach market size (≈3.3 g).
Priming Prepositional Phrase Attachment: Evidence from Eye-Tracking and Event-Related Potentials
Authors: Boudewyn Megan A. , Zirnstein Megan , Swaab Tamara Y. , Traxler Matthew J.
Published: July 2013

Three syntactic-priming experiments investigated the effect of structurally similar or dissimilar prime sentences on the processing of target sentences, using eye tracking (Experiment 1) and event-related potentials (ERPs) (Experiments 2 and 3) All three experiments tested readers' response to sentences containing a temporary syntactic ambiguity. The ambiguity occurred because a prepositional phrase modifier (PP-modifier) could attach either to a preceding verb or to a preceding noun. Previous experiments have established that (a) noun-modifying expressions are harder to process than verb-modifying expressions (when test sentences are presented in isolation); and (b) for other kinds of sentences, processing a structurally similar prime sentence can facilitate processing a target sentence. The experiments reported here were designed to determine whether a structurally similar prime could facilitate processing of noun-attached modifiers and whether such facilitation reflected syntactic-structure-building or semantic processes. These findings have implications for accounts of structural priming during online comprehension and for accounts of syntactic representation and processing in comprehension.
Auditory Clicks Distort Perceived Velocity but Only When the System has to Rely on Extraretinal Signals
Authors: Makin Alexis D. J. , Lawson Rebecca , Bertamini Marco , Pickering Jayne
Published: July 2013

Previous work has found that repetitive auditory stimulation (click trains) increases the subjective velocity of subsequently presented moving stimuli. We ask whether the effect of click trains is stronger for retinal velocity signals (produced when the target moves across the retina) or for extraretinal velocity signals (produced during smooth pursuit eye movements, when target motion across the retina is limited). In Experiment 1, participants viewed leftward or rightward moving single dot targets, travelling at speeds from 7.5 to 17.5 deg/s. They estimated velocity at the end of each trial. Prior presentation of auditory click trains increased estimated velocity, but only in the pursuit condition, where estimates were based on extraretinal velocity signals. Experiment 2 generalized this result to vertical motion. Experiment 3 found that the effect of clicks during pursuit disappeared when participants tracked across a visually textured background that provided strong local motion cues. Together these results suggest that auditory click trains selectively affect extraretinal velocity signals. This novel finding suggests that the cross-modal integration required for auditory click trains to influence subjective velocity operates at later stages of processing.
Cost of early snowmelt in terms of reduced irrigation deliveries
Authors: Benson Aaron , Williams Ryan
Published: July 2013

Climate change and windborne dust are expected to change snowmelt timing. Dust from agricultural activities is estimated to cause snow to melt two to four weeks earlier in some regions. Early snowmelt may decrease deliveries of irrigation water when reservoirs provide flood protection and irrigation water. To date, the quantity decrease has not been determined. We identify when early snowmelt causes earlier water release, and calculate the quantity decrease in water deliveries downstream. Irrigation reductions are negligible unless the dam capacity is less than twice the quantity of annual runoff, and unless snowmelt occurs more than four weeks early.
ARH directs megalin to the endocytic recycling compartment to regulate its proteolysis and gene expression
Authors: Shah Mehul , Baterina Oscar Y. , Taupin Vanessa , Farquhar Marilyn G.
Published: July 2013

Receptors internalized by endocytosis can return to the plasma membrane (PM) directly from early endosomes (EE; fast recycling) or they can traffic from EE to the endocytic recycling compartment (ERC) and recycle from there (slow recycling). How receptors are sorted for trafficking along these two pathways remains unclear. Here we show that autosomal recessive hypercholesterolemia (ARH) is required for trafficking of megalin, a member of the LDL receptor family, from EE to the ERC by coupling it to dynein; in the absence of ARH, megalin returns directly to the PM from EE via the connecdenn2/Rab35 fast recycling pathway. Binding of ARH to the endocytic adaptor AP-2 prevents fast recycling of megalin. ARH-mediated trafficking of megalin to the ERC is necessary for γ-secretase mediated cleavage of megalin and release of a tail fragment that mediates transcriptional repression. These results identify a novel mechanism for sorting receptors for trafficking to the ERC and link ERC trafficking to regulated intramembrane proteolysis (RIP) and expression of megalin.
Vinculin–actin interaction couples actin retrograde flow to focal adhesions, but is dispensable for focal adhesion growth
Authors: Thievessen Ingo , Thompson Peter M. , Berlemont Sylvain , Plevock Karen M. , Plotnikov Sergey V. , Zemljic-Harpf Alice , Ross Robert S. , Davidson Michael W. , Danuser Gaudenz , Campbell Sharon L. , Waterman Clare M.
Published: July 2013

In migrating cells, integrin-based focal adhesions (FAs) assemble in protruding lamellipodia in association with rapid filamentous actin (F-actin) assembly and retrograde flow. How dynamic F-actin is coupled to FA is not known. We analyzed the role of vinculin in integrating F-actin and FA dynamics by vinculin gene disruption in primary fibroblasts. Vinculin slowed F-actin flow in maturing FA to establish a lamellipodium–lamellum border and generate high extracellular matrix (ECM) traction forces. In addition, vinculin promoted nascent FA formation and turnover in lamellipodia and inhibited the frequency and rate of FA maturation. Characterization of a vinculin point mutant that specifically disrupts F-actin binding showed that vinculin–F-actin interaction is critical for these functions. However, FA growth rate correlated with F-actin flow speed independently of vinculin. Thus, vinculin functions as a molecular clutch, organizing leading edge F-actin, generating ECM traction, and promoting FA formation and turnover, but vinculin is dispensible for FA growth.
Regulation of the Anaphase-promoting Complex/Cyclosome bybimAAPC3and Proteolysis of NIMA
Authors: Ye Xiang S. , Fincher Russell R. , Tang Alice , Osmani Aysha H. , Osmani Stephen A.
Published: July 2013

Surprisingly, although highly temperature-sensitive, thebimA1APC3anaphase-promoting complex/cyclosome (APC/C) mutation does not cause arrest of mitotic exit. Instead, rapid inactivation ofbimA1APC3is shown to promote repeating oscillations of chromosome condensation and decondensation, activation and inactivation of NIMA and p34cdc2kinases, and accumulation and degradation of NIMA, which all coordinately cycle multiple times without causing nuclear division. ThesebimA1APC3-induced cell cycle oscillations require active NIMA, because a nimA5 +bimA1APC3double mutant arrests in a mitotic state with very high p34cdc2H1 kinase activity. NIMA protein instability during S phase and G2 was also found to be controlled by the APC/C. The bimA1APC3mutation therefore first inactivates the APC/C but then allows its activation in a cyclic manner; these cycles depend on NIMA. We hypothesize that bimAAPC3could be part of a cell cycle clock mechanism that is reset after inactivation ofbimA1APC3. ThebimA1APC3mutation may also make the APC/C resistant to activation by mitotic substrates of the APC/C, such as cyclin B, Polo, and NIMA, causing mitotic delay. Once these regulators accumulate, they activate the APC/C, and cells exit from mitosis, which then allows this cycle to repeat. The data indicate thatbimAAPC3regulates the APC/C in a NIMA-dependent manner.
A Polymer Model for the Structural Organization of Chromatin Loops and Minibands in Interphase Chromosomes
Authors: Ostashevsky Joseph
Published: July 2013

A quantitative model of interphase chromosome higher-order structure is presented based on the isochore model of the genome and results obtained in the field of copolymer research. G1 chromosomes are approximated in the model as multiblock copolymers of the 30-nm chromatin fiber, which alternately contain two types of 0.5- to 1-Mbp blocks (R and G minibands) differing in GC content and DNA-bound proteins. A G1 chromosome forms a single-chain string of loop clusters (micelles), with each loop ∼1–2 Mbp in size. The number of ∼20 loops per micelle was estimated from the dependence of geometrical versus genomic distances between two points on a G1 chromosome. The greater degree of chromatin extension in R versus G minibands and a difference in the replication time for these minibands (early S phase for R versus late S phase for G) are explained in this model as a result of the location of R minibands at micelle cores and G minibands at loop apices. The estimated number of micelles per nucleus is close to the observed number of replication clusters at the onset of S phase. A relationship between chromosomal and nuclear sizes for several types of higher eukaryotic cells (insects, plants, and mammals) is well described through the micelle structure of interphase chromosomes. For yeast cells, this relationship is described by a linear coil configuration of chromosomes.
Role of Akt and c-Jun N-terminal Kinase 2 in Apoptosis Induced by Interleukin-4 Deprivation
Authors: Cerezo Ana , Martı́nez-A Carlos , Lanzarot Diego , Fischer Siegmund , Franke Thomas F. , Rebollo Angelita
Published: July 2013

We have shown previously that interleukin-4 (IL-4) protects TS1αβ cells from apoptosis, but very little is known about the mechanism by which IL-4 exerts this effect. We found that Akt activity, which is dependent on phosphatidylinositol 3 kinase, is reduced in IL-4-deprived TS1αβ cells. Overexpression of wild-type Akt or a constitutively active Akt mutant protects cells from IL-4 deprivation-induced apoptosis. Readdition of IL-4 before the commitment point is able to restore Akt activity. We also show expression and c-Jun N-terminal kinase 2 activation after IL-4 deprivation. Overexpression of the constitutively activated Akt mutant in IL-4-deprived cells correlates with inhibition of c-Jun N-terminal kinase 2 activity. Finally, TS1αβ survival is independent of Bcl-2, Bcl-x, or Bax.
Morphogenetic Effects of Neuregulin (Neu Differentiation Factor) in Cultured Epithelial Cells
Authors: Chausovsky Alexander , Tsarfaty Ilan , Kam Zvi , Yarden Yosef , Geiger Benjamin , Bershadsky Alexander D.
Published: July 2013

Neuregulin, or neu differentiation factor, induces cell proliferation or differentiation through interaction with members of the ErbB family of receptor tyrosine kinases. We report that neuregulin can also induce profound morphogenic responses in cultured epithelial cells of different origins. These effects include scattering of small epithelial islands and rearrangement of larger cell islands into ordered ring-shaped arrays with internal lumens. The ring-forming cells are interconnected by cadherin- and β-catenin-containing adherens junctions. In confluent cultures, neuregulin treatment induces formation of circular lumenlike gaps in the monolayer. Both cell scattering and ring formation are accompanied by a marked increase in cell motility that is independent of hepatocyte growth factor/scatter factor and its receptor (c-Met). Affinity-labeling experiments implied that a combination of ErbB-2 with ErbB-3 mediates the morphogenic signal of neuregulin in gastric cells. Indeed, a similar morphogenic effect could be reconstituted in nonresponsive cells by coexpression of ErbB-2 and -3. We conclude that a heterodimer between the kinase-defective neuregulin receptor, ErbB-3, and the coreceptor, ErbB-2, mediates the morphogenetic action of neuregulin.
Gene-Environment Interplay in Twin Models
Authors: Verhulst Brad , Hatemi Peter K.
Published: July 2013

In this article, we respond to Shultziner's critique that argues that identical twins are more alike not because of genetic similarity, but because they select into more similar environments and respond to stimuli in comparable ways, and that these effects bias twin model estimates to such an extent that they are invalid. The essay further argues that the theory and methods that undergird twin models, as well as the empirical studies which rely upon them, are unaware of these potential biases. We correct this and other misunderstandings in the essay and find that gene-environment (GE) interplay is a well-articulated concept in behavior genetics and political science, operationalized as gene-environment correlation and gene-environment interaction. Both are incorporated into interpretations of the classical twin design (CTD) and estimated in numerous empirical studies through extensions of the CTD. We then conduct simulations to quantify the influence of GE interplay on estimates from the CTD. Due to the criticism's mischaracterization of the CTD and GE interplay, combined with the absence of any empirical evidence to counter what is presented in the extant literature and this article, we conclude that the critique does not enhance our understanding of the processes that drive political traits, genetic or otherwise.
Avoiding problems with hydrogen misplacement in reporting crystal structures
Authors: Bernal Ivan , Watkins Steven F.
Published: July 2013

Intermolecular hydrogen bonding is an integral part of many crystal structures. Hydrogen bonding sometimes results in one-, two- or three-dimensional supramolecular assemblies, a common feature of which is positional disorder of H atoms related to space-group symmetry. Yet some reported structures fail to include all possible donor–acceptor close contacts, or to seek H-atom electron densities associated with apparentD—H...Atrios, while some H-atom positions violate principles of chemistry or crystal physics. Modern diffraction equipment and sophisticated computing systems provide high-quality data; thus, failure to characterize and report fully an accurate, complete and physically correct hydrogen-bonding model should not be acceptable. We illustrate the relevant issues with three published examples in the hope of slowing the proliferation of these problems, with the scientifically desirable goal of improving the accuracy of crystallographic models while also providing improved search keys for information retrieval.
Poly[[μ-(1-azaniumylethane-1,1-diyl)bis(hydrogen phosphonato)]sodium]: a powder X-ray diffraction study
Authors: Rukiah Mwaffak , Assaad Thaer
Published: July 2013

The title two-dimensional coordination polymer, [Na(C2H8NO6P2)]n, was characterized using powder X-ray diffraction data and its structure refined using the Rietveld method. The asymmetric unit contains one Na+cation and one (1-azaniumylethane-1,1-diyl)bis(hydrogen phosphonate) anion. The central Na+cation exhibits distorted octahedral coordination geometry involving two deprotonated O atoms, two hydroxy O atoms and two double-bonded O atoms of the bisphosphonate anion. Pairs of sodium-centred octahedra share edges and the pairs are in turn connected to each other by the biphosphonate anion to form a two-dimensional network parallel to the (001) plane. The polymeric layers are connected by strong O—H...O hydrogen bonding between the hydroxy group and one of the free O atoms of the bisphosphonate anion to generate a three-dimensional network. Further stabilization of the crystal structure is achived by N—H...O and O—H...O hydrogen bonding.
A three-dimensional coordination polymer of 3-(3,5-dicarboxybenzyloxy)benzoic acid with zinc
Authors: Patra Ranjan , Goldberg Israel
Published: July 2013

The synthesis is reported of the tricarboxylic acid 3-(3,5-dicarboxybenzyloxy)benzoic acid (H3L) and the product of its reaction under solvothermal conditions with ZnIIcations, namely poly[[μ6-3-(3,5-dicarboxylatobenzyloxy)benzoato](dimethylformamide)-μ3-hydroxido-dizinc(II)], [Zn2(C16H9O7)(OH)(C3H7NO)]n, the formation of which is associated with complete deprotonation of H3L. Its crystal structure consists of a single-framework coordination polymer of the organicL3−ligand with ZnIIcations in a 1:2 ratio, with additional hydroxide and dimethylformamide (DMF) ligands coordinated to the ZnIIcentres. The ZnIIcations are characterized by coordination numbers of 5 and 6, being bridged to each other by hydroxide ligands. In the polymeric framework, the carboxylate- and hydroxy-bridged ZnIIcations are arranged in coordination-tessellated columns, which propagate along theaaxis of the crystal structure, and eachL3−ligand links to seven different ZnIIcentresviaZn—O bonds of two different columns. The coordination framework, composed of [Zn2(L)(OH)(DMF)]nunits, forms an open architecture, the channel voids within it being filled by the zinc-coordinating DMF ligands. This report provides the first structural evidence for the formation of coordination polymers with H3L viamultiple metal–ligand bonds through its carboxylate groups.
Stable isotope‐based community metrics as a tool to identify patterns in food web structure in east African estuaries
Authors: Abrantes Kátya G. , Barnett Adam , Bouillon Steven
Published: July 2013

Quantitative tools to describe biological communities are important for conservation and ecological management. The analysis of trophic structure can be used to quantitatively describe communities. Stable isotope analysis is useful to describe trophic organization, but statistical models that allow the identification of general patterns and comparisons between systems/sampling periods have only recently been developed.

Here, stable isotope‐based Bayesian community‐wide metrics are used to investigate patterns in trophic structure in five estuaries that differ in size, sediment yield and catchment vegetation cover (C3/C4): the Zambezi in Mozambique, the Tana in Kenya and the Rianila, the Betsiboka and Pangalanes Canal (sampled at Ambila) in Madagascar.

Primary producers, invertebrates and fish of different trophic ecologies were sampled at each estuary before and after the 2010–2011 wet season. Trophic length, estimated based on δ15N, varied between 3·6 (Ambila) and 4·7 levels (Zambezi) and did not vary seasonally for any estuary. Trophic structure differed the most at Ambila, where trophic diversity and trophic redundancy were lower than at the other estuaries. Among the four open estuaries, the Betsiboka and Tana (C4‐dominated) had lower trophic diversity than the Zambezi and Rianila (C3‐dominated), probably due to the high loads of suspended sediment, which limited the availability of aquatic sources.

There was seasonality in trophic structure at Ambila and Betsiboka, as trophic diversity increased and trophic redundancy decreased from the prewet to the postwet season. For Ambila, this probably resulted from the higher variability and availability of sources after the wet season, which allowed diets to diversify. For the Betsiboka, where aquatic productivity is low, this was likely due to a greater input of terrestrial material during the wet season.

The comparative analysis of community‐wide metrics was useful to detect patterns in trophic structure and identify differences/similarities in trophic organization related to environmental conditions. However, more widespread application of these approaches across different faunal communities in contrasting ecosystems is required to allow identification of robust large‐scale patterns in trophic structure. The approach used here may also find application in comparing food web organization before and after impacts or monitoring ecological recovery after rehabilitation.
Evaluating breeding and metamorph occupancy and vernal pool management effects for wood frogs using a hierarchical model
Authors: Green Adam W. , Hooten Mevin B. , Grant Evan H. Campbell , Bailey Larissa L.
Published: July 2013

World‐wide declines in amphibian populations are often attributed to loss of habitat and exploitation; additionally, climate change may play an important role in future declines. Despite protection of habitat, amphibians relying on temporary habitats, such as vernal pools, may need active management to maintain their populations under forecasts of warming temperatures and more variable precipitation. However, few studies have examined the factors influencing where these species choose to breed (breeding occurrence) and the conditional likelihood of successful metamorphosis, while accounting for imperfect detection.

We developed an occupancy model and estimated parameters within a Bayesian framework to investigate the factors influencing probabilities of wood frogLithobates sylvaticabreeding and successful metamorphosis at Patuxent Research Refuge, Maryland,USA. Our objectives were to obtain estimates of breeding occurrence and metamorph occupancy and evaluate the success of current management actions.

The probabilities of wood frog breeding and successful metamorphosis varied by year and were positively related to the pond's typical hydroperiod length and annual precipitation. Contrary to our predictions, previous occupancy states had little effect on breeding and metamorph occupancy probabilities, which is likely to be due to high correlation of occupancy with hydroperiod length. Additionally, we did not observe a relationship between breeding occupancy probabilities and the spatial arrangement of pools. Although sample sizes were small, management actions resulted in an increase in both breeding and metamorph occupancy probabilities.

Synthesis and applications. We demonstrate that management actions targeting short‐hydroperiod pools favourably influence both components of breeding success. However, continued monitoring is needed to determine whether managed pools remain suitable for wood frogs. With predicted changes in climate and a positive relationship between breeding occupancy and winter precipitation, a proactive focus on active management of vernal pools may provide a means to maintain wood frog populations in the future.
Using long‐term monitoring of red fox populations to assess changes in rodent control practices
Authors: Jacquot Marion , Coeurdassier Michaël , Couval Geoffroy , Renaude Régis , Pleydell David , Truchetet Denis , Raoul Francis , Giraudoux Patrick
Published: July 2013

Pest control is a global issue for agriculture, health, biodiversity conservation and economy. Anticoagulant rodenticides are used over large areas to control rodent pests and can cause widespread poisoning of nontarget wildlife. In France, bromadiolone is the only pesticide authorized to control the water vole Arvicola terrestris Scherman, in grasslands. Since 2001, legislation has been in place to replace curative treatments by preventive ones and limit the quantity of rodenticide used. As the legislation took effect over time, the impact on red fox Vulpes vulpes populations was monitored.

Fox populations and bromadiolone treatments were monitored in the Doubs Department (5000 km² area), France. Fox counts were carried out during spring, and vole control was primarily conducted in autumn. Relative fox densities (Kilometric Abundance Index: KAI) obtained per commune for year n (2004–2009) were related to treatments achieved during year n−1 (2003–2008). Treatments from year n−2 were used to investigate possible delayed responses in fox populations.

Kilometric Abundance Index of foxes was significantly related to treatment intensities in years n−1 and n−2. The impact was greatest in a large area (>1000 km²), where intensive treatments were achieved in 2003. Fox KAI generally remained dramatically low in this area until 2005, after which a partial recovery was observed.

The same area was treated again from 2006 to 2008 but with only half the amount of bait per hectare that was used in 2003. These treatments were followed by a moderate decrease in fox populations.

Synthesis and applications: We have established, for the first time on a regional scale, the negative impact of a rodenticide on fox populations. We have shown that a shift to preventive treatments with reduced anticoagulant rodenticide use is less harmful to fox populations. However, to approach a zero impact, treatments should be reduced further by limitation of bait quantities authorized per hectare and per commune and using alternative methods to chemical control. Long‐term monitoring of wildlife populations using index methods can provide valuable information about the adverse effects of pesticides; therefore, we recommend their inclusion in the assessment of pest management practices.
Student Projects that Make a Meaningful and Lasting Contribution to Course Content
Authors: Schmidt Shelly J.
Published: July 2013

The objective of this teaching tip is to share with others an idea of how to transform student projects from a dead‐end process to a value‐added end product, value‐added end products that make a meaningful and lasting contribution to course content for use by future students.
Students’ Perceptions of an Experiential Learning Activity Designed to Develop Knowledge of Food and Food Preparation Methods
Authors: Leveritt Michael , Ball Lauren , Desbrow Jane
Published: July 2013

The aim of this study was to describe student learning after completing an experiential learning task that was designed to develop students’ knowledge of food and food preparation methods. The task required students to follow a special diet and then complete a daily online journal entry about the experience for other students to read and review. Twenty‐five Masters level Nutrition and Dietetics students participated in individual semistructured interviews to evaluate the experiential learning activity. Interview transcripts were analyzed thematically using a constant comparative approach. Students perceived that the experiential learning activity successfully increased their understanding of the special diet they had been allocated, but learning from reviewing other students’ journal posts was less effective. They also felt better able to relate to the challenges facing future patients when receiving prescribed diets. The level of engagement and enjoyment resulting from the activity was more variable with some students finding the challenge of the activity a burden despite reporting good learning outcomes. Further evaluation of this approach to nutrition education in other areas is warranted.
The phytochemical, EGCG, extends lifespan by reducing liver and kidney function damage and improving age‐associated inflammation and oxidative stress in healthy rats
Authors: Niu Yucun , Na Lixin , Feng Rennan , Gong Liya , Zhao Yue , Li Qiang , Li Ying , Sun Changhao
Published: July 2013

It is known that phytochemicals have many potential health benefits in humans. The aim of this study was to investigate the effects of long‐term consumption of the phytochemical, epigallocatechin gallate (EGCG), on body growth, disease protection, and lifespan in healthy rats. 68 male weaning Wistar rats were randomly divided into the control and EGCG groups. Variables influencing lifespan such as blood pressure, serum glucose and lipids, inflammation, and oxidative stress were dynamically determined from weaning to death. The median lifespan of controls was 92.5 weeks. EGCG increased median lifespan to 105.0 weeks and delayed death by approximately 8–12 weeks. Blood pressure and serum glucose and lipids significantly increased with age in both groups compared with the levels at 0 week. However, there were no differences in these variables between the two groups during the whole lifespan. Inflammation and oxidative stress significantly increased with age in both groups compared with 0 week and were significantly lower in serum and liver and kidney tissues in the EGCG group. Damage to liver and kidney function was significantly alleviated in the EGCG group. In addition, EGCG decreased the mRNA and protein expressions of transcription factor NF‐κB and increased the upstream protein expressions of silent mating type information regulation two homolog one (SIRT1) and forkhead box class O 3a (FOXO3a). In conclusion, EGCG extends lifespan in healthy rats by reducing liver and kidney damage and improving age‐associated inflammation and oxidative stress through the inhibition of NF‐κB signaling by activating the longevity factors FoxO3a and SIRT1.
Notch1 signaling modulates neuronal progenitor activity in the subventricular zone in response to aging and focal ischemia
Authors: Sun Fen , Mao XiaoOu , Xie Lin , Ding Meiping , Shao Bei , Jin Kunlin
Published: July 2013

Neurogenesis diminishes with aging and ischemia‐induced neurogenesis also occurs, but reduced in aged brain. Currently, the cellular and molecular pathways mediating these effects remain largely unknown. Our previous study has shown that Notch1 signaling regulates neurogenesis in subventricular zone (SVZ) of young adult brain after focal ischemia, but whether a similar effect occurs in aged normal and ischemic animals is unknown. Here, we used normal and ischemic aged rat brains to investigate whether Notch1 signaling was involved in the reduction of neurogenesis in response to aging and modulates neurogenesis in aged brains after focal ischemia. By Western blot, we found that Notch1 and Jagged1 expression in the SVZ of aged brain was significantly reduced compared with young adult brain. Consistently, the activated form of Notch1 (Notch intracellular domain; NICD) expression was also declined. Immunohistochemistry confirmed that expression and activation of Notch1 signaling in the SVZ of aged brain were reduced. Double or triple immunostaining showed that that Notch1 was mainly expressed in doublecortin (DCX)‐positive cells, whereas Jagged1 was predominantly expressed in astroglial cells in the SVZ of normal aged rat brain. In addition, disruption or activation of Notch1 signaling altered the number of proliferating cells labeled by bromodeoxyuridine (BrdU) and DCX in the SVZ of aged brain. Moreover, ischemia‐induced cell proliferation in the SVZ of aged brain was enhanced by activating the Notch1 pathway and was suppressed by inhibiting the Notch1 signaling. Reduced infarct volume and improved motor deficits were also observed in Notch1 activator–treated aged ischemic rats. Our data suggest that Notch1 signaling modulates the SVZ neurogenesis in aged brain in normal and ischemic conditions.
Elevated microRNA‐34a in obesity reduces NAD+ levels and SIRT1 activity by directly targeting NAMPT
Authors: Choi Sung‐E , Fu Ting , Seok Sunmi , Kim Dong‐Hyun , Yu Eunkyung , Lee Kwan‐Woo , Kang Yup , Li Xiaoling , Kemper Byron , Kemper Jongsook K.
Published: July 2013

SIRT1 is an NAD+‐dependent deacetylase that is implicated in prevention of many age‐related diseases including metabolic disorders. As SIRT1 deacetylase activity is dependent on NAD+ levels and the development of compounds that directly activate SIRT1 has been controversial, indirectly activating SIRT1 through enhancing NAD+ bioavailability has received increasing attention. NAD+ levels are reduced in obesity and the aged, but the underlying mechanisms remain unclear. We recently showed that hepatic microRNA‐34a (miR‐34a), which is elevated in obesity, directly targets and decreases SIRT1 expression. Here, we further show that miR‐34a reduces NAD+ levels and SIRT1 activity by targeting NAMPT, the rate‐limiting enzyme for NAD+ biosynthesis. A functional binding site for miR‐34a is present in the 3′ UTR of NAMPT mRNA. Hepatic overexpression of miR‐34a reduced NAMPT/NAD+ levels, increased acetylation of the SIRT1 target transcriptional regulators, PGC‐1α, SREBP‐1c, FXR, and NF‐κB, and resulted in obesity‐mimetic outcomes. The decreased NAMPT/NAD+ levels were independent of miR‐34a effects on SIRT1 levels as they were also observed in SIRT1 liver‐specific knockout mice. Further, the miR‐34a‐mediated decreases were reversed by treatment with the NAD+ intermediate, nicotinamide mononucleotide. Conversely, antagonism of miR‐34a in diet‐induced obese mice restored NAMPT/NAD+ levels and alleviated steatosis, inflammation, and glucose intolerance. Anti‐miR‐34a‐mediated increases in NAD+ levels were attenuated when NAMPT was downregulated. Our findings reveal a novel function of miR‐34a in reducing both SIRT1 expression and activity in obesity. The miR‐34a/NAMPT axis presents a potential target for treating obesity‐ and aging‐related diseases involving SIRT1 dysfunction like steatosis and type 2 diabetes.
Commodity index investment and food prices: does the “Masters Hypothesis” explain recent price spikes?
Authors: Irwin Scott H.
Published: July 2013

The “Masters Hypothesis” is the claim that unprecedented buying pressure in recent years from commodity index investors created massive bubbles in food and energy prices. The purpose of this article is to review the evidence from recent studies that investigate the empirical relationship between index investment and price movements in agricultural futures markets. One line of research uses time‐series regression tests, such as Granger causality tests, to investigate the relationship between price movements and index positions. This research provides little evidence in support of the Masters Hypothesis in agricultural futures markets. A second line of research uses cross‐sectional regression tests and studies in this area provide very limited evidence in favor of the Masters Hypothesis for agricultural futures markets. A third line of research investigates whether there is a significant relationship between commodity index trading and the difference, or spread, between futures prices of different contract maturities on the same date. These studies report a range of results depending on the type of test. However, the bulk of the evidence indicates either no relationship or a negative relationship, which is once again inconsistent with the Masters Hypothesis. Overall, this growing body of literature fails to find compelling evidence that buying pressure from commodity index investment in recent years caused a massive bubble in agricultural futures prices. The Masters Hypothesis is simply not a valid characterization of reality.