bluuebunny/crossref_metadata_2025 huggingface dataset:
A novel Xenopus homologue of bone morphogenetic protein‐7 (BMP‐7)
Authors: Wang Shouwen , Krinks Marie , Kleinwaks Logan , Moos Malcolm
Published: October 2010

We identified aXenopus gene closely related to mammalian bone morphogenetic protein (BMP)‐7 (also termed osteogenic protein‐1 or OP‐1). It resembles the mammalian gene in primary structure and expression pattern much more closely than does a previously described Xenopus homologue, originally termed XBMP‐7 [Nishimatsu, Suzuki, Shoda, Murakami and Ueno (1992) Biochem. Biophys. Res. Commun. 186, 1487–1495]. The novel gene has therefore been designated XBMP‐7 and the gene described earlier has been renamed XBMP‐7R (M. Moos and N. Ueno, unpublished work). It has a broad distribution, primarily in the anterior and posterior ventral regions during gastrulation, subsequently becoming prominent at different stages in a wide variety of structures (eyes, neural structures, heart, pronephros, posterior ventral region and other structures), paralleling the distribution of XBMP‐4 closely. However, its expression begins later than that of XBMP‐4 during gastrulation. Lithium treatment of embryos concentrates the XBMP‐7 expression in the expanded eye and heart structures. Ventral overexpression of XBMP‐7 produces large protrusions that ultimately develop colouration characteristic of haemoglobin, which is confirmed by markedly expanded expression of α‐globin. Dorsal overexpression suppresses dorsal anterior structures. Molecular analysis of animal caps overexpressing XBMP‐7 reveals induction of markers associated with ventral and haematopoietic tissue, which is consistent with whole‐embryo overexpression results. Globin induction by XBMP‐7 can be blocked by a truncated BMP receptor previously shown to interrupt BMP‐4 signalling, indicating XBMP‐7 also interacts with this receptor. Our data support the concept that XBMP‐7 may play a variety of roles during embryogenesis, and suggest a possible role in haematogenesis.
Oxytocin and milk removal are required for post‐partum mammary‐gland development
Authors: Wagner Kay‐Uwe , Young W. , Liu Xiuwen , Ginns Edward , Li Minglin , Furth Priscilla , Hennighausen Lothar
Published: October 2010

The oxytocin (OT)–neurophysin preprohormone is synthesized in the paraventricular and supraoptic nuclei of the hypothalamus. OT is cleaved from its precursor, transported from the magnocellular neurons to the posterior pituitary and secreted during labour and upon the suckling stimulus of pups. OT induces the contraction of myoepithelial cells surrounding the mammary alveoli, which leads to the ejection of milk. Mice deficient in OT are unable to nurse their young. Administration of OT enabled OT‐deficient dams to nurse. We now show that OT and milk removal are also required for post‐partum alveolar proliferation and mammary‐gland function. Alveolar density and mammary epithelial‐cell differentiation at parturition was similar in wild‐type and OT‐deficient dams. However, within 12 h after parturition approx. 2% of the alveolar cells in wild‐type dams incorporated DNA and proliferated, but virtually no proliferation was detected in OT‐deficient dams. Continuous suckling of pups led to the expansion of lobulo‐alveolar units in wild‐type but not in OT‐deficient dams. Despite suckling and the presence of systemic lactogenic hormones, mammary tissue in OT‐deficient dams partially involuted. Our studies demonstrate that post‐partum alveolar proliferation requires not only systemic lactogenic hormones, such as prolactin, but also the presence of OT in conjunction with continued milk removal.
Functional analysis of a 38 kilobase region on chromosome XVI inSaccharomyces cerevisiae
Authors: Ushinsky Sophia , Bussey Howard , Ahmed Alia , Wang Ying , Friesen James , Storms Reginald
Published: October 2010

In this report we assess the functional importance of 16 open reading frames (ORFs) contained within a 38 780 base‐pair region immediately adjacent to the centromere on the right arm of chromosome XVI in Saccharomyces cerevisiae. This analysis involved replacing one copy of each ORF in a diploid strain with a cassette encoding the green fluorescent protein from the jellyfish Aequorea victoria and HIS3. Each replacement cassette was generated by PCR using oligonucleotide pairs with 45‐base extensions complementary to sequences immediately upstream and downstream of the target gene’s coding region. After replacement of the targeted genes, each gene‐replacement strain was subjected to a series of genetic and phenotypic tests to assess the functional importance of the deleted gene. This analysis showed that two ORFs were essential, one for spores to germinate and another for vegetative growth. A third gene encoded a copper‐fist‐like transcription factor that was required for proper bud‐site selection. One of the 16 ORFs was duplicated, a situation not observed in the strain used to sequence the yeast genome (S288C). RNA analysis showed 11 of the 16 ORFs in this region expressed steady‐state poly(A+) RNA levels that were greater than or equal to 2% of the level expressed from the yeast actin gene, ACT1.
The transcriptional regulatory strategy of the rat tissue kallikrein gene family
Authors: Kroon Evert , MacDonald Raymond , Hammer Robert
Published: October 2010

We have analysed the transcriptional regulatory strategy of the rat tissue kallikrein gene family, a strategy that provides universal submandibular gland expression of all family members coupled with otherwise disparate expression of individual members in a wide variety of organs. To test whether a locus control region (LCR) or individual gene enhancers control the family, the expression patterns of rat kallikrein genes were examined in transgenic mice bearing a series of rat genomic fragments spanning the kallikrein locus. Each fragment, present in recombinant P1 phage clones, contained two or three linked members of the rat family. Rat (r) genes KLK1, KLK2, KLK3, KLK7, KLK8, KLK9 and KLK10 on four different P1 clones were all correctly expressed at high levels in the submandibular glands of transgenic mice and in general showed the correct extra‐salivary patterns characteristic of each family member. Moreover, when the neighbouring family members rKLK1 and rKLK3 were separated on non‐overlapping fragments and tested in mice, each transgene was expressed correctly in the submandibular gland and in other organs characteristic of that gene. Thus the family locus is not controlled by an LCR; rather each gene appears to have an associated transcriptional enhancer that specifies high submandibular expression and contributes to the additional organ specificity of the family member.
Effects of Long Term Exposure to High‐CO2 During Storage at 0°C on Biology and Infectivity of Botrytis cinerea in Red Chicory
Authors: Bertolini P. , Baraldi E. , Mari M. , Trufelli Lazzarin B., R.
Published: October 2010

The effects on Botrytis cinerea of prolonged exposures to CO2‐enriched atmospheres were studied in vitro and in vivo at 0°C. Mycelial growth on potato dextrose agar decreased linearly with increasing CO2 concentrations from 5, 10, 15 and 20% CO2. The growth reduction was greater after 30–40 days of incubation. A reduced production of sclerotia in air by the colonies formerly exposed to various CO2 concentrations was also detected. Conidial germination was delayed and the amount of germinated conidia decreased with increased CO2 and at 20% CO2 it was inhibited. Germ tube elongation was affected in the same way. In artificially inoculated red chicory, lesion area caused by B. cinerea decreased with increasing concentrations of CO2 up to 60 days storage, later only 10 and 15% CO2 were really effective, while in the final inspection after 120 days all the concentration tested showed a low efficacy. Similar results were obtained in naturally infected chicory where the severity of the disease decreased by increasing CO2 from 5 to 10%, higher values did not improve the suppressive effect or determined, after 150 days of storage, an increased vulnerability of the tissues to disease due to the phytotoxic effects of the gas. An atmosphere enriched with 10% CO2 is advised to suppress Botrytis rot during storage at 0°C of red chicory.
Latency of Botrytis cinerea Pers.: Fr. and Biochemical Studies During Growth and Ripening of Two Grape Berry Cultivars, Respectively Susceptible and Resistant to Grey Mould
Authors: Pezet R. , Viret O. , Perret C. , Tabacchi R.
Published: October 2010

Latency and development of Botrytis cinerea were assessed under field conditions and after artificial inoculation of two grape varieties, Gamay (susceptible) and Gamaret (resistant). When the percentage of latent Botrytis was the same for both varieties, severity of visible grey mould remained very low in Gamaret berries, while Gamay clusters were destroyed by the disease to a high percentage. Some biochemical parameters were measured in berries, such as constitutive and induced anti‐fungal compounds, polymeric proanthocyanidins and lipid peroxidation products as markers of senescence. Differences were observed in polymeric proanthocyanidins (PPRA) of Gamaret compared with those of Gamay. Concentration and mean degree of polymerization (mDP) of PPRA were always higher in the berries of the resistant variety. The inhibitory effect of Gamaret PPRA on enzyme activity remained until harvest whereas Gamay PPRA lost their inhibitory activity at the beginning of véraison. Based on these results, resistance to B. cinerea seems to be linked to the maintainance of the fungus in its latent form in berries, mainly due to the ability of Gamaret PPRA to inhibit macerating fungal enzyme activities.
Combination of Pseudomonas aeruginosa and Pochonia chlamydosporia for Control of Root‐Infecting Fungi in Tomato
Authors: Siddiqui I. A. , Shaukat S. S.
Published: October 2010

A plant growth‐promoting rhizobacterium, Pseudomonas aeruginosa strain IE‐6, and a fungal antagonist, Pochonia chlamydosporia, were tested for their ability to inhibit mycelial growth of root‐infecting fungi under laboratory conditions including Macrophomina phaseolina, Fusarium oxysporum, F. solani and Rhizoctonia solani. Biocontrol effectiveness of the bacterium and the fungus alone or in combination was also determined for the control of root‐infecting fungi under field conditions. In a dual‐culture plate assay, the colonies of P. chlamydosporia and P. aeruginosa met each other and no further growth of either organism occurred. Against M. phaseolina, F. solani and R. solani, an ethyl acetate extract of the culture filtrates of P. aeruginosa inhibited fungal growth greater than the hexane extract, but against F. oxysporum the hexane extract caused greater inhibition of fungal growth. By contrast, against M. phaseolina, F. oxysporum and F. solani, the hexane extract of P. chlamydosporia was more effective in the inhibition of fungal growth than the ethyl acetate fraction. Ethyl acetate extracts of P. aeruginosa at 1.0 mg/ml not only inhibited the radial colony growth of R. solani but also lysed the fungal mycelium. P. aeruginosa produced siderophores and hydrogen cyanide under laboratory conditions. Field experiments conducted in 1997 and repeated in 1998 revealed that Pochonia chlamydosporia and P. aeruginosa significantly suppressed the root‐infecting fungi M. phaseolina, F. oxysporum, F. solani and R. solani and that the combination of the two caused greater inhibition of the fungal pathogens than either alone. Application of P. chlamydosporia and P. aeruginosa as a soil drench also resulted in enhanced growth of tomato plants.
Detection and Molecular Characterization of a Phytoplasma Associated with Big Bud Disease of Tomatoes in Jordan
Authors: Anfoka Ghandi H. , Khalil Amjad B. , Fattash Isam
Published: October 2010

Tomato big bud was detected for the first time in tomato plants (Lycopersicon esculentum Mill.) in the eastern region (Al‐Mafraq) of Jordan. Infected plants showed proliferation of lateral shoots, hypertrophic calyxes and greening of flower petals. The presence of phytoplasmas in diseased tomato plants was demonstrated using polymerase chain reaction (PCR) assays. The amplified DNAs yielded products of 1.8 kb (primer pair P1/P7) and 1.2 kb (primer pair R16F2/R2) by direct and nested‐PCR, respectively. DNA from tomato isolates T1 and T2 could not be amplified in the nested‐PCR assays when the aster yellow‐specific primer pair R16(1)F1/R1 was used, suggesting that the phytoplasma in these isolates is not genetically related to the 16SrI (aster yellows) group. After restriction fragment length polymorphism (RFLP) analyses, using four endonuclease enzymes (HhaI, RsaI, AluI and Bsp143I) similar patterns were formed among the digested 1.2 kb PCR products of two tomato isolates suggesting that both isolates belonged to the same phytoplasma. Compared with the RFLP profile of the reference strains, no difference in the digestion pattern was found between the tomato isolates and that of the catharanthus phyllody agent from Sudan, indicating that the phytoplasma belongs to 16SrDNA VI (clover proliferation) group.
Lauric Acid Exhibits Antifungal Activity Against Plant Pathogenic Fungi
Authors: Walters D. R. , Walker R. L. , Walker K. C.
Published: October 2010

This study aimed at examining the effects of the saturated fatty acid lauric acid on mycelial growth of Rhizoctonia solani and Pythium ultimum and on infection of barley seedlings with Blumeria graminis f. sp. hordei. Mycelial growth of R. solani and P. ultimum in agar culture was significantly reduced by lauric acid at concentrations of 100 μm and above, while no fungal growth occurred in liquid culture at concentrations above 50 μm. Application of lauric acid at concentrations ranging from 250 to 1000 μm to barley leaves before or after inoculation with B. graminis f. sp. hordei led to significant reductions in infection. This study provides the first report of the activity of lauric acid against plant pathogenic fungi and indicates the need for investigation of its mechanism of action.
Integrated Control of Sclerotium rolfsii on Groundnut in South Africa
Authors: Cilliers A. J. , Pretorius Z. A. , Van Wyk P. S.
Published: October 2010

Sclerotium rolfsii Sacc. causes disease of numerous crop plants worldwide, including groundnuts. Control of this pathogen is difficult as it produces sclerotia which overwinter in the soil to emerge as inoculum and cause disease the following season. Various chemical, biological and cultural control strategies have been suggested and implemented, some of which have reduced disease incidence in the field. No studies have yet been undertaken in South Africa to control this disease on groundnut, either chemically, biologically or by cultural practices. In this study, several strategies were investigated for the control of S. rolfsii on groundnuts. Difenoconazole was identified as a fungicide that could possibly be applied in combination with Trichoderma harzianum, a biological antagonist of S. rolfsii, above carbendazim and flusilazole, and chlorothalonil. Difenoconazole significantly reduced the growth rate of S. rolfsii but not of T. harzianum. The cultivation of infected fields with an inversion plough significantly reduced infection of groundnuts by S. rolfsii and also improved the quality of the produce, while yield was not increased. Lower plant density increased the incidence of disease in an infected field, and is therefore not considered to be a viable form of cultural control.
Plant Species, Host Age and Host Genotype Effects on Meloidogyne incognita Biocontrol by Pseudomonas fluorescens Strain CHA0 and its Genetically‐Modified Derivatives
Authors: Siddiqui I. A. , Shaukat S. S.
Published: October 2010

Pseudomonas fluorescens strain CHA0 and its antibiotic overproducing derivative CHA0/pME3424 repeatedly reduced Meloidogyne incognita galling on tomato, brinjal, mungbean and soya bean roots but not in chilli. An antibiotic‐deficient derivative, CHA89, did not reduce nematode invasion in any of the plant species tested. When plant species were compared, bacterial inoculants afforded better protection to tomato, mungbean and soya bean roots against root‐knot nematodes than to brinjal and chilli. Antibiotic overproducing strain CHA0/pME3424 markedly reduced fresh shoot weights of chilli and mungbean while antibiotic‐deficient strain CHA89 enhanced fresh shoot weights of mungbean. While strains CHA0 had no significant impact on fresh root weights of any of the plant species, strain CHA0/pME3424 consistently reduced fresh root weights of brinjal and mungbean. In none of the plant species the bacterial strains had an influence on protein contents of the leaves. Regardless of the plant species, the three bacterial strains did not differ markedly in their rhizosphere colonization pattern. However, colonization was highest in brinjal rhizosphere and lowest in the mungbean rhizosphere. A slight host genotype effect on the biocontrol performance of the bacterial inoculants was also detected at cultivar level. When five soya bean cultivars were compared, biocontrol bacteria exhibited best suppression of the root‐knot nematode in cv. Ajmeri. Antibiotic overproducing strain CHA0/pME3424 substantially reduced fresh shoot weights of the soya bean cultivars Centuray 84 and NARC‐I while strain CHA89 enhanced shoot weights of the cultivars Ajmeri, William‐82 and NARC‐II. Wild type strain CHA0 had no significant impact on fresh shoot weights of any of the soya bean cultivars. Strain CHA0/pME3424 reduced fresh weights of root of Century 84, NARC‐I and NARC‐II while strain CHA89 increased root weights. Bacterial rhizosphere colonization was highest in variety NARC‐I and lowest in variety Ajmeri. Plant age had a significant impact on the biocontrol performance of bacterial inoculants against nematodes. The biocontrol effect of all bacterial strains was more prominent during early growth stage (7 days after nematode inoculation). A strong negative correlation between bacterial rhizosphere colonization and nematode invasion in soya bean roots was observed.
Genetic and Pathogenic Variation Among Tobacco Black Shank Strains of Phytophthora parasitica var. nicotianae from the Main Tobacco Growing in China
Authors: Zhang X. G. , Sun W. X. , Guo L. , Yu J. F. , Chang C. J.
Published: October 2010

Pathogenic and genetic variability among seven populations of Phytophthora parasitica var. nicotianae from individual tobacco fields (Yunnan, Shandong, Henan, Heilongjiang, Shanxi, Fujian and Sichuan provinces) were investigated using pathogenicity and randomly amplified polymorphic DNA (RAPD) analyses; 63 strains were isolated from different fields of seven tobacco growing regions, using tobacco cv. Hongda as a baiting host. Pathogenic variability was evaluated in greenhouse studies using five tobacco cultivars that have different levels of resistance to tobacco black shank; 75 and 73% of the strains were pathogenic on M3 and M4, 29 and 33% on M1 and M2, and 94% were pathogenic on M5, respectively. Disease severity incited by different strains varied significantly on individual tobacco cultivars. The percentage of strains pathogenic on different cultivars varied among locations. Genotypic variation among 63 strains was evaluated by RAPD analysis. Ten primers detected 89 polymorphic bands. Cluster and principal coordinates analysed cluster groups. the minor group contained 26 strains, and major group contained 37 strains. Estimates of genetic diversity based on RAPD analysis ranged from 0.24 to 0.34 within populations to 0.36 among all strains from all populations. Phytophthora parasitica var. nicotianae populations were genotypically and phenotypically variable, but no distinct genotypic differences were identified among populations from the seven locations.
Characterization of New Highly Virulent German Isolates of Bremia lactucae and Efficiency of Resistance in Wild Lactuca spp. Germplasm
Authors: Lebeda A. , Zinkernagel V.
Published: October 2010

Four German isolates (FS1, SR2, SAW1 and DEG2) of Bremia lactucae originating from lettuce cultivars with R‐factors R18 and Dm6 + R36 were used for detailed characterization of virulence factors (v‐factors) and for the study of the resistance efficiency in wild Lactuca spp. germplasm. The highest complexity of v‐phenotype was recognized in isolate DEG2, which overcomes resistance in cv. Mariska (R18) and line CS‐RL (L. serriola × L. sativa, R18 + ?), until now known as resistant to all known races of B. lactucae in Europe. However, some sparse sporulation also occurred on cv. Titan (Dm6 + R36). The isolates SR2 and SAW1 overcome the resistance based on the gene R36, but are avirulent to R18. The v‐phenotype of SR2 is highly complex with the most important v‐factors being present except for v14 and v18. The isolate FS1 is the first in Germany originating from a cultivar with R18 (cv. Samourai). The search for efficient sources of resistance in 64 accessions of 11 wild Lactuca spp. and primitive forms of L. sativa showed broad variation in accession–isolate interactions. Expression of race‐specific resistance in wild Lactuca spp. (L. serriola, L. viminea, L. virosa) was recorded frequently. Lactuca indica and L. saligna could be considered as the most efficient sources of resistance against isolates FS1, SR2 and SAW1. The isolate DEG2 showed the highest level of virulence. On seedlings of L. saligna, which is considered as a most important source of resistance against B. lactucae, there was frequently recorded limited sporulation, however this response cannot be considered as a susceptible. Except for some L. saligna accessions (CGN 05310 and CGN 05315), the resistance to all studied isolates was only observed in one accession of L. serriola (PI 253467).
Identification of Two Blast Resistance Genes in a Rice Variety, Digu
Authors: Chen X. W. , Li S. G. , Xu J. C. , Zhai W. X. , Ling Z. Z. , Ma B. T. , Wang Y. P. , Wang W. M. , Cao G. , Ma Y. Q. , Shang J. J. , Zhao X. F. , Zhou K. D. , Zhu L. H.
Published: October 2010

Blast, caused by Magnaporthe grisea is one of most serious diseases of rice worldwide. A Chinese local rice variety, Digu, with durable blast resistance, is one of the important resources for rice breeding for resistance to blast (M. grisea) in China. The objectives of the current study were to assess the identity of the resistance genes in Digu and to determine the chromosomal location by molecular marker tagging. Two susceptible varieties to blast, Lijiangxintuanheigu (LTH) and Jiangnanxiangnuo (JNXN), a number of different varieties, each containing one blast resistance gene, Piks, Pia, Pik, Pi‐b, Pi‐kp, Pi‐ta2, Pi‐ta, Pi‐z, Pi‐i, Pi‐km, Pi‐zt, Pi‐t and Pi‐11, and the progeny populations from the crosses between Digu and each of these varieties were analysed with Chinese blast isolates. We found that the resistance of Digu to each of the two Chinese blast isolates, ZB13 and ZB15, were controlled by two single dominant genes, separately. The two genes are different from the known blast resistance genes and, therefore, designated as Pi‐d(t)1 and Pi‐d(t)2. By using bulked segregation method and molecular marker analysis in corresponding F2 populations, Pi‐d(t)1 was located on chromosome 2 with a distance of 1.2 and 10.6 cM to restriction fragment length polymorphism (RFLP) markers G1314A and G45, respectively. And Pi‐d(t)2 was located on chromosome 6 with a distance of 3.2 and 3.4 cM to simple sequence repeat markers RM527 and RM3, respectively. We also developed a novel strategy of resistance gene analogue (RGA) assay with uneven polymerase chain reaction (PCR) to further tag the two genes and successfully identified two RGA markers, SPO01 and SPO03, which were co‐segregated toPi‐d(t)1 and Pi‐d(t)2, respectively, in their corresponding F2 populations. These results provide essential information for further utilization of the Digu's blast resistance genes in rice disease resistance breeding and positional cloning of these genes.
Chromosome Polymorphism of the Obligate Biotrophic Parasite Plasmodiophora brassicae
Authors: Graf H. , Fähling M , Siemens J.
Published: October 2010

Electrophoretic karyotypes of different isolates of Plasmodiophora brassicae, the causative agent of clubroot of cabbage, using contour‐clamped homogeneous electric field gel electrophoresis (CHEF) revealed chromosome polymorphism in this obligate parasite. Ribosomal RNA (rRNA) genes have been localized on three chromosomes (I, IV and V) of P. brassicae of the 16 chromosomal bands, which can be distinguished for the single‐spore isolate ‘e3’. In comparison with this isolate three other single‐spore isolates showed chromosome polymorphism by size of chromosomal bands and by hybridization pattern with rRNA gene fragments and other Plasmodiophora‐specific DNA fragments.
An Allele‐specific PCR Assay for Detecting Azoxystrobin‐resistant Alternaria Isolates from Pistachio in California
Authors: Ma Z. , Michailides T. J.
Published: October 2010

Alternaria late blight caused by Alternaria spp. in the alternata, tenuissima and arborescens species‐groups is one of the most common fungal diseases of pistachio in California. A single point mutation resulting in the replacement of a glycine by an alanine at codon 143 (G143A) in the mitochondrial cytochrome b (cyt b) has been found in all azoxystrobin‐resistant isolates of these three species from California pistachio. In this study, a pair of allele‐specific polymerase chain reaction (PCR) primers was developed to detect this point mutation. The allele‐specific PCR assay coupled with a rapid DNA extraction method could detect azoxystrobin‐resistant Alternaria isolates in a few hours. The allele‐specific PCR method was also reliable for detecting azoxystrobin‐resistant Alternaria directly in both laboratory‐inoculated and naturally infected pistachio leaves.
Crystalline lens parameters in infancy
Authors: Wood Ivan C. J. , Mutti Donald O. , Zadnik Karla
Published: October 2010

Despite the importance of lens power to ocular development, few data are available regarding infant crystalline lens parameters. Lens and corneal radii of curvature were measured in the horizontal meridian using a video‐based keratophakometer, and refractive error was measured by cycloplegic retinoscopy in 19 out of 27 infants ranging in age from 3 to 18 months. The median refractive error was + 1.50 D, and the median corneal power was 43.5 D. Using previously reported values for axial ocular dimensions, the median anterior and posterior lens radii of curvature were 8.7 and 5.6 mm, respectively, both substantially flatter than infant schematic eye values. The median equivalent refractive index of the lens was 1.49, considerably higher than previous reported schematic values for infants or children. There was a significant reduction in hyperopia with age (r = −0.47, P = 0.043), but no age‐related trends in lens or corneal radii of curvature, suggesting that calculated values for lens power and equivalent index may undergo substantial decline with age during early childhood development as axial length increases. Most of the decrease in lens power (75%) may be due to decreases in equivalent index rather than to flattening of the surface radii of curvature. Videophakometry appears to be a feasible and useful technique for documenting the role of the crystalline lens in infant ocular development.
Electronic measurement of microchannel plate pulse height distributions
Authors: Gamboa E. J. , Huntington C. M. , Harding E. C. , Drake R. P.
Published: October 2010

Microchannel plates are a central component of the x-ray framing cameras used as analog imagers in many plasma experiment diagnostic systems. The microchannel plate serves as an amplifying element, increasing the electronic signal from incident radiation by factors of 103–105, with a broad pulse-height distribution. Seeking to optimize the photon-to-electron conversion efficiency and noise distribution of x-ray cameras, we will characterize the pulse-height distribution of the electron output from a single microchannel plate. Replacing the framing camera’s phosphor-coated fiber optic screen with a charge-collection plate and coupling to a low-noise multichannel analyzer, we quantified the distribution in the total charge generated per photon event. The electronically measured pulse height distribution is used to estimate the signal-to-noise ratio of radiographic images from framing cameras.
Spectroscopic diagnostics for liquid lithium divertor studies on National Spherical Torus Experiment
Authors: Soukhanovskii V. A. , Roquemore A. L. , Bell R. E. , Kaita R. , Kugel H. W.
Published: October 2010

The use of lithium-coated plasma facing components for plasma density control is studied in the National Spherical Torus Experiment (NSTX). A recently installed liquid lithium divertor (LLD) module has a porous molybdenum surface, separated by a stainless steel liner from a heated copper substrate. Lithium is deposited on the LLD from two evaporators. Two new spectroscopic diagnostics are installed to study the plasma surface interactions on the LLD: (1) A 20-element absolute extreme ultraviolet (AXUV) diode array with a 6 nm bandpass filter centered at 121.6 nm (the Lyman-α transition) for spatially resolved divertor recycling rate measurements in the highly reflective LLD environment, and (2) an ultraviolet-visible-near infrared R=0.67 m imaging Czerny–Turner spectrometer for spatially resolved divertor D I, Li I-II, C I-IV, Mo I, D2, LiD, CD emission and ion temperature on and around the LLD module. The use of photometrically calibrated measurements together with atomic physics factors enables studies of recycling and impurity particle fluxes as functions of LLD temperature, ion flux, and divertor geometry.
Control of the hot electrons produced by laser interaction with nanolayered target
Authors: Cao Lihua , Gu Yuqiu , Zhao Zongqing , Cao Leifeng , Huang Wenzhong , Zhou Weimin , Cai H. B. , He X. T. , Yu Wei , Yu M. Y.
Published: October 2010

Hot electrons generated by short-pulse-laser interaction with nanolayered target (NT) are investigated using two-dimensional particle-in-cell simulation. Compared to the planar target, the NT leads to more efficient conversion of laser energy to the kinetic energy of the accelerated electrons. However, the energy absorption by the NT decreases at both too-low and too-high laser intensities. At lower laser intensities it is because of the weaker electric and magnetic fields generated by the hot-electron jets and smaller relativistic skin depth. At higher laser intensities it is because of the damage or destruction of the layered structure by the laser field. On the other hand, the dependence of the conversion efficiency and hot-electron number on the duration of the (short) laser pulse and the nanolayer length is weak. Control of the hot-electron characteristics by tailoring the parameters of the laser and the NT is discussed.
Primary measurement of total ultrasonic power with improved accuracy in rf voltage measurement
Authors: Dubey P. K. , Kumar Ashok , Kumar Yudhisther , Gupta Reeta , Joshi Deepa
Published: October 2010

Out of the various existing ultrasonic power measurement techniques, the radiation force balance method using microbalance is most widely used in low power (below 1 W) regime. The major source of uncertainty associated with this technique is the error in ac voltage measurement applied to the transducer for the generation of ultrasonic waves. The sources that deteriorate the ac voltage measurement accuracy include cable length and impedance mismatch. We introduce a new differential peak to peak measurement approach to reduce the ac voltage measurement error. The method holds the average peak amplitude of each polarity. Ultralow offset difference amplifier is used to measure peak to peak voltage. The method is insensitive to the variations in the dc offset of the source. The functionality of this method has been tested and compared with the conventional rf voltage measurement method. The output of this proposed technique is dc, which can be measured with an error of less than 0.1%.
Derivation via free energy conservation constraints of gyrofluid equations with finite-gyroradius electromagnetic nonlinearities
Authors: Scott B.
Published: October 2010

The derivation of electromagnetic gyrofluid equations is made systematic by using the Hermite polynomial form of the underlying delta-f gyrokinetic distribution function. The gyrokinetic free-energy functional is explicitly used to set up the model. The gyrofluid free energy follows directly. The interaction term in the gyrokinetic Lagrangian is used to obtain the gyrofluid counterpart, from which the polarization equation follows. One closure rule is decided for taking moments over the kinetic gyroaveraging operator. These steps fix the rest of the derivation of the conservative part of the gyrofluid equations. Dissipation is then added in a form to obtain positive definite dissipation and to obtain the collisional fluid equations in their appropriate limit. Existing results are recovered, with the addition of a completely consistent model for finite gyroradius effects in the nonlinearities responsible for magnetic reconnection.
Wavelet analyses using parallel computing for plasma turbulence studies
Authors: Fujisawa A. , Shimizu A. , Itoh K. , Nagashima Y. , Yamada T. , Inagaki S. , Matsuoka K. , Itoh S.-I.
Published: October 2010

The wavelet analyses have been carried out, using a cluster of personal computer, on the signal of electric field fluctuations measured with heavy ion beam probes in the compact helical system stellarator. The results have revealed the intermittent characteristics of turbulence and of the nonlinear couplings between elemental waves of turbulence. The usage of parallel computing is found to successfully reduce the calculation time as inversely proportional to the CPU number used the cluster, which shows the nature of “embarrassingly parallel computation.” The present example of the wavelet analyses clearly demonstrates the importance of the advanced analyzing methods and the parallel computation for the modern studies of plasma turbulence.
On the plume splitting of pulsed laser ablated Fe and Al plasmas
Authors: Mahmood S. , Rawat R. S. , Darby M. S. B. , Zakaullah M. , Springham S. V. , Tan T. L. , Lee P.
Published: October 2010

A time resolved imaging study of pulsed laser ablated Fe and Al plasma plumes with specific interest in the splitting of plumes into the slow and fast moving components as they expand through the background argon gas at different pressures is reported. The material ablation was achieved using a Q-switched Nd:YAG (yttrium aluminum garnet) laser operating at 532 nm with a pulse duration of ∼8 ns full width at half maximum and a fluence of 30 Jcm−2 at the target surface. Typical time resolved images with low magnification show that the splitting occurs at moderate background gas pressures (0.5 and 1.0 mbar for Fe, and 0.2 mbar for Al plasma plumes). The plume splitting did not occur for higher background gas pressures.
Solitary waves in an ultrarelativistic degenerate dense plasma
Authors: Mamun A. A. , Shukla P. K.
Published: October 2010

Solitary waves in an ultrarelativistic degenerate dense plasma have been investigated by the reductive perturbation method. The modified Korteweg–de Vries equation has been derived and its numerical solutions have been analyzed to identify the basic features of spherical electrostatic solitary structures that may form in such a degenerate dense plasma. The implications of our results in compact astrophysical objects, particularly in white dwarfs, have been briefly discussed.
Simulating polarizable molecular ionic liquids with Drude oscillators
Authors: Schröder Christian , Steinhauser Othmar
Published: October 2010

The Drude oscillator model is applied to the molecular ionic liquid 1-ethyl-3-methyl-imidazolium triflate. The range of manageable Drude charges is tested. The strength of the polarizability is systematically varied from 0% to 100%. The influence on the structure, single particle dynamics, and collective dielectric properties is investigated. The generalized dielectric constant can be decomposed into a dielectric permittivity, a dielectric conductivity, and an optical dielectric constant ϵ∞. The major part of the static generalized dielectric constant comes from the collective rotation of the ions, i.e., the dielectric permittivity. The translational contribution from the dielectric conductivity is about 58% of the dielectric permittivity. For the evaluation of the optical dielectric contribution, the computational dielectric theory was adapted to the case of heterogeneous polarizabilities. In case of 100% polarizability, it reaches a value of approximately 2.
The effects of rapid thermal annealing on the electrical, optical, and structural properties of Nb:TiO2 multilayer electrodes with an inserted nanoscale Ag layer for organic solar cells
Authors: Park Jun-Hyuk , Choi Yoon-Young , Kim Han-Ki , Lee Hyun Hwi , Na Seok-In
Published: October 2010

We investigated the effects of rapid thermal annealing (RTA) on the electrical, optical, structural, interfacial, and surface properties of Nb:TiO2 (NTO)–Ag–NTO multilayer electrodes inserting a nanoscale Ag layer for application in organic solar cells (OSCs). Up to an annealing temperature of 500 °C, the resistivity and optical transmittance of the NTO–Ag–NTO electrodes were stably maintained due to the absence of Ag outdiffusion. The effective activation of the Nb in the NTO layer led to a slight decrease in the resistivity and an increase in the band gap caused by the Burstein–Moss effect. However, increasing the RTA temperature above 600 °C resulted in degradation of the NTO–Ag–NTO multilayer electrode due to severe Ag diffusion. Based on the synchrotron x-ray scattering and x-ray photoelectron spectroscopy analyses results, the electrical properties of the NTO–Ag–NTO electrodes are correlated with the microstructure and interfacial diffusion of each layer. In addition, it was found that the performance of the OSC was critically dependent on the RTA temperature of the NTO–Ag–NTO electrodes even though the as-deposited NTO–Ag–NTO electrode had a fairly low resistivity. This indicates that the activation of Nb dopants in the top NTO layer plays an important role in the extraction of carriers from the organic layer to the anode (NTO–Ag–NTO) electrode.
Low energy-consumption plasma electrolytic oxidation based on grid cathode
Authors: Zhang X. M. , Tian X. B. , Yang S. Q. , Gong C. Z. , Fu R. K. Y. , Chu P. K.
Published: October 2010

Plasma electrolytic oxidation (PEO) has attracted widespread attention owing to the simplicity of operation and the excellent properties of the formed coating. However, wider applications of PEO have been limited due to the high power consumption. This work describes the design and performance of a novel technique named shorter distance PEO (SD-PEO), which is intended for lowering the energy consumption. The key feature of the method is the application of grid cathode to eliminate the gaseous envelope effect and to block of the exchange of charge carries during SD-PEO process. Compared to PEO carried out at a normal electrode distance, e.g., 50 mm, both the voltage drop and the joule heat consumed in the electrolyte at a shorter distance, e.g., of 5 mm (SD-PEO) are relatively small. Consequently, the energy consumption rendered by the novel SD-PEO method may decrease by more than 25%. Our results reveal that SD-PEO is a low energy-consumption microarc oxidation technique with more potential in industry applications.
High resolution IR spectroscopy of HDO and HDO(N2)n in helium nanodroplets
Authors: Gutberlet Anna , Schwaab Gerhard , Havenith Martina
Published: October 2010

We report on the IR-spectra of HDO and aggregates of HDO and N2 embedded in superfluid helium nanodroplets in the region of the bound O–D stretch vibration. The R(0) transition 000→101 of HDO was observed at 2738.157 50(7) cm−1. The linewidth of this transition was determined to be 0.060(4) cm−1. In HDO(N2)n aggregates, the bound O–D stretch vibration was observed at 2732.36(1) and 2730.62(1) cm−1 for n=1 and n=2, respectively. The line broadening amounts to 1.86(7) and 2.73(7) cm−1, which correspond to lifetimes of 2.84(1) and 1.94(5) ps.
Interface chemistry and electronic structure of GaN/MgAl2O4 revealed by angle-resolved photoemission spectroscopy
Authors: He G. , Chikyow T. , Chichibu Shigefusa F.
Published: October 2010

By modifying the MgAl2O4 substrate surface using chemical etching and thermal passivation, high-quality GaN films have been achieved on the MgAl2O4 (111) substrate via metalorganic chemical vapor deposition. The interface chemistry and electronic structure of GaN/MgAl2O4 interface have been investigated by angle-resolved photoemission spectroscopy. It has been noted that thermal passivation leads to the formation of Al2O3 buffered layer, which remains thermally stable during deposition and are primarily responsible for the epitaxial growth of GaN on MgAl2O4 (111) substrate.
Dissociation of core-valence doubly excited states in NO followed by atomic Auger decay
Authors: Hikosaka Y. , Kaneyasu T. , Matsushita T. , Tamenori Y. , Shigemasa E.
Published: October 2010

The decay processes of core-valence doubly excited states near the N K edge of NO have been studied using electron spectroscopy. Electron yields measured as a function of photon energy and kinetic energy enable the clear identification of atomic Auger lines associated with the dissociation of doubly excited states. The atomic Auger lines exhibit Doppler profiles, allowing the entire reaction scheme of such dissociation processes to be determined.
Impact of crystallization behavior of SrxTiyOz films on electrical properties of metal-insulator-metal capacitors with TiN electrodes
Authors: Pawlak M. A. , Kaczer B. , Kim M.-S. , Popovici M. , Tomida K. , Swerts J. , Opsomer K. , Polspoel W. , Favia P. , Vrancken C. , Demeurisse C. , Wang W.-C. , Afanas’ev V. V. , Vandervorst W. , Bender H. , Debusschere I. , Altimime L. , Kittl J. A.
Published: October 2010

Metastable perovskite SrxTiyOz (STO) films were formed over a wide composition range by crystallization of layers grown by atomic layer deposition. An expansion of the lattice, decrease in permittivity and mild increase in band gap are observed with increasing Sr content. Sr-rich films [Sr/(Sr+Ti)∼62 at. %] show significant improvement in leakage current at low equivalent oxide thicknesses (EOT) as compared to stoichiometric films (Sr/(Sr+Ti) ∼50 at. %). TiN/STO/TiN capacitors with leakage ∼10−6 A/cm2 at 1 V were obtained at 0.6 nm EOT for crystalline Sr-rich STO. The difference in leakage behavior was found to correlate with different microstructures developed during crystallization.
A first-principles scheme to phonons of high temperature phase: No imaginary modes for cubic SrTiO3
Authors: Wang Yi , Saal James E. , Mei Zhigang , Wu Pingping , Wang Jianjun , Shang Shunli , Liu Zi-Kui , Chen Long-Qing
Published: October 2010

The issue of imaginary phonon modes predicted by first-principles calculations for high-temperature structures of most materials has been a longstanding problem for decades. We propose that the observed high-temperature structures are actually dynamic averages of related low-temperature structures. This theory is used to predict the phonon dispersions of cubic SrTiO3. The calculated phonon dispersions for the cubic phase, using the force constants calculated from the tetragonal phases, are found to be in remarkably good agreement with existing neutron data, without exhibiting any imaginary phonon modes.
Multi-year fertility reduction in free-roaming feral horses with single-injection immunocontraceptive formulations
Authors: Gray Meeghan E. , Thain David S. , Cameron Elissa Z. , Miller Lowell A.
Published: October 2010

Context. Contraception is increasingly used as a management technique to reduce fertility in wildlife populations; however, the feasibility of contraceptive formulations has been limited until recently because they have required multiple treatments to achieve prolonged infertility. Aims. We tested the efficacy and evaluated potential side effects of two contraceptive formulations, a porcine zona pellucida (PZP) formulation, SpayVac® and a gonadotrophin-releasing hormone (GnRH) formulation GonaCon-B™, in a population of free-roaming feral horses (Equus caballus). Both formulations were developed to provide several years of infertility with one injection. Methods. Females were treated in June 2005 with either GonaCon-B (n = 24), SpayVac (n = 20), adjuvant only (n = 22), or received no injection (n = 18). Females were monitored for fertility status year round for 3 years after treatment. Key results. Both contraceptive treatments significantly reduced fertility for 3 years. Fertility rates for GonaCon-B mares were 39%, 42% and 31%, respectively, and 37%, 50% and 44% for SpayVac mares. During the same seasons, 61%, 67% and 76% of control females were fertile. We found no significant effects from contraceptive treatment on the sex ratio of foals, birthing season or foal survival. Conclusions. These results demonstrated that both vaccines are capable of significantly reducing fertility for several years without boosters. Implications. Contraceptive vaccines examined in the present study represent a useful tool for the management of feral horses, because of their being efficacious for 3 years in the absence of booster immunisations.
Does nest-site selection influence bobwhite nesting success in south Florida?
Authors: Singh Aditya , Hines Tommy C. , Percival H. Franklin , Oli Madan K.
Published: October 2010

Context. Nest-site selection can influence nesting success, and thus population dynamics, of many species of ground-nesting birds. Despite the economic importance as a game species, populations of northern bobwhites have been declining throughout the southern United States. This paper reports the nesting ecology of northern bobwhites (Colinus virginianus) on Babcock-Webb Wildlife Management Area, Florida, USA, and illustrates the influence of landscape composition and structure on bobwhite nest-site selection and nest fate. Aim. To investigate nest-site selection by bobwhites, to evaluate the influence of landscape composition and structure on nest-site selection, and to identify factors influencing nesting success. Methods. We used distance-based habitat-selection methods and logistic regression to test for nest-site selection and to investigate the influence of landscape characteristics on nesting success. Key results. Bobwhites preferred to establish nests closer to food plots and farther away from water bodies than expected; other habitats were neither preferred nor avoided. Nesting success did not vary across years, differ among habitats or among burn treatments, and none of the habitat and landscape variables we measured significantly influenced the probability that a nest would be successful. Conclusions. Bobwhites preferred to place nests closer to food plots. However, habitat features of nest sites did not influence bobwhite nesting success. These results may indicate that random nest predation by meso-mammalian predators may currently determine fates of bobwhite nests in south Florida, or that population density is low enough that only suitable nesting sites are occupied. Implications. Our results suggest that increasing the density of linear food plots, and maintaining a structurally diverse pine–palmetto and dry prairie habitat that provides adequate nesting cover could contribute to augmenting bobwhite nesting habitat.