bluuebunny/crossref_metadata_2025 huggingface dataset:
Accounting for High Stress Gradient by a Modified Weibull Failure Theory
Authors: Ekwaro-Osire S. , Khandaker M. P. H. , Gautam K.
Published: January 2008

A high stress gradient occurs in a component when the stress, due to external loading, rises asymptotically. The Weibull failure theory overestimates the probability of failure for components with high stress gradients generated due to the geometric irregularities, material mismatch, thermal mismatch, and contact loading. A modified Weibull failure theory is proposed in this paper. The method is based on the weight function method. The modified Weibull failure theory was applied to two specimens, and the results showed the ability of the proposed theory to handle high stress gradients. The theory considers variable equivalent stress intensity factors along the faces of cracks; hence, it considers the strength of a specimen to be dependent on the stress field.
Optical Microscopy-Aided Indentation Tests
Authors: Doman D. A. , Bauer R. , Warkentin A.
Published: January 2008

The contact characteristics of ceramic-metallic interactions are of critical importance in the design of high-speed ceramic rolling contact bearings. This type of interaction is not described well by traditional indentation tests since small displacements and barely discernable indentations are encountered. In this work, an optical microscopy system is described that is used to measure small indenter displacements accurately. Images of the indenter are taken throughout the test and processed using sophisticated edge detection algorithms to accurately determine the position of the center of the indenter. Thus, the indenter displacements on the order of 1μm can be measured independent of any structural flexibility present in the test apparatus. Experimental indentation tests using an alumina indenter mounted on a stainless steel post were performed and processed with the optical system. The results were compared to existing analytical models for fully elastic and elastoplastic cases as well as a finite element model developed using a Johnson–Cook plasticity material model. The comparison shows that the analytical models do not predict the experimental results well, whereas the finite element model agrees very well. Subsequent analysis of the finite element model shows that the size of the contact zone and pressure distributions, both very important in the design of bearings, can be more accurately described than the traditional analytical treatments.
Modeling Texture Evolution During Friction Stir Welding of Stainless Steel With Comparison to Experiments
Authors: Cho Jae-Hyung , Dawson Paul R.
Published: January 2008

Texture evolution during friction stir welding of stainless steel was investigated using a polycrystal plasticity model together with a three-dimensional, thermomechanically coupled, finite element formulation. The influence of frictional conditions with the tool pin and shoulder on the flow in the through-thickness direction was examined in terms of their impact on the evolving crystallographic texture. Trends in regard to the strengthening and weakening of the texture are discussed in relation to the relative magnitudes of the deformation rate and spin. Finally, the computed textures are compared to electron backscatter diffraction measurements and are discussed with respect to distributions along orientational fibers and the dominant texture components along the fibers.
100% Accuracy in Automatic Face Recognition
Authors: Jenkins R. , Burton A. M.
Published: January 2008

Accurate face recognition is critical for many security applications. Current automatic face-recognition systems are defeated by natural changes in lighting and pose, which often affect face images more profoundly than changes in identity. The only system that can reliably cope with such variability is a human observer who is familiar with the faces concerned. We modeled human familiarity by using image averaging to derive stable face representations from naturally varying photographs. This simple procedure increased the accuracy of an industry standard face-recognition algorithm from 54% to 100%, bringing the robust performance of a familiar human to an automated system.
Enriched Pt-Re-Os Isotope Systematics in Plume Lavas Explained by Metasomatic Sulfides
Authors: Luguet Ambre , Graham Pearson D. , Nowell Geoff M. , Dreher Scott T. , Coggon Judith A. , Spetsius Zdislav V. , Parman Stephen W.
Published: January 2008

To explain the elevated osmium isotope (
186
Os-
187
Os) signatures in oceanic basalts, the possibility of material flux from the metallic core into the crust has been invoked. This hypothesis conflicts with theoretical constraints on Earth's thermal and dynamic history. To test the veracity and uniqueness of elevated
186
Os-
187
Os in tracing core-mantle exchange, we present highly siderophile element analyses of pyroxenites, eclogites plus their sulfides, and new
186
Os/
188
Os measurements on pyroxenites and platinum-rich alloys. Modeling shows that involvement in the mantle source of either bulk pyroxenite or, more likely, metasomatic sulfides derived from either pyroxenite or peridotite melts can explain the
186
Os-
187
Os signatures of oceanic basalts. This removes the requirement for core-mantle exchange and provides an effective mechanism for generating Os isotope diversity in basalt source regions.
Comparison of Comet 81P/Wild 2 Dust with Interplanetary Dust from Comets
Authors: Ishii Hope A. , Bradley John P. , Dai Zu Rong , Chi Miaofang , Kearsley Anton T. , Burchell Mark J. , Browning Nigel D. , Molster Frank
Published: January 2008

The Stardust mission returned the first sample of a known outer solar system body, comet 81P/Wild 2, to Earth. The sample was expected to resemble chondritic porous interplanetary dust particles because many, and possibly all, such particles are derived from comets. Here, we report that the most abundant and most recognizable silicate materials in chondritic porous interplanetary dust particles appear to be absent from the returned sample, indicating that indigenous outer nebula material is probably rare in 81P/Wild 2. Instead, the sample resembles chondritic meteorites from the asteroid belt, composed mostly of inner solar nebula materials. This surprising finding emphasizes the petrogenetic continuum between comets and asteroids and elevates the astrophysical importance of stratospheric chondritic porous interplanetary dust particles as a precious source of the most cosmically primitive astromaterials.
Cytomegalovirus Strain Diversity in Seropositive Women
Authors: Novak Zdenek , Ross Shannon A. , Patro Raj Kumar , Pati Sunil Kumar , Kumbla Rekha A. , Brice Sallie , Boppana Suresh B.
Published: January 2008

Infection and reinfection with multiple cytomegalovirus (CMV) strains have been shown to occur in immunocompromised individuals, sexually transmitted disease clinic attendees, and children attending day care centers. To characterize the CMV diversity in healthy seropositive individuals, 16 CMV PCR-positive specimens from 113 seropositive women were analyzed for glycoprotein gN and gB genotypes by cloning, followed by nucleotide sequencing of the plasmid DNA and/or restriction fragment length polymorphism (RFLP). The results showed that most (93.7%) of the PCR-positive specimens contained multiple gN and/or gB genomic variants, suggesting that the majority of women were infected with more than one virus strain. The results also showed that the RFLP technique might not be sufficiently sensitive to detect all of the genomic variants present in a sample.
Genotype-Specific Genomic Markers Associated with Primary Hepatomas, Based on Complete Genomic Sequencing of Hepatitis B Virus
Authors: Sung Joseph J. Y. , Tsui Stephen K. W. , Tse Chi-Hang , Ng Eddie Y. T. , Leung Kwong-Sak , Lee Kin-Hong , Mok Tony S. K. , Bartholomeusz Angeline , Au Thomas C. C. , Tsoi Kelvin K. F. , Locarnini Stephen , Chan Henry L. Y.
Published: January 2008

We aimed to identify genomic markers in hepatitis B virus (HBV) that are associated with hepatocellular carcinoma (HCC) development by comparing the complete genomic sequences of HBVs among patients with HCC and those without. One hundred patients with HBV-related HCC and 100 age-matched HBV-infected non-HCC patients (controls) were studied. HBV DNA from serum was directly sequenced to study the whole viral genome. Data mining and rule learning were employed to develop diagnostic algorithms. An independent cohort of 132 cases (43 HCC and 89 non-HCC) was used to validate the accuracy of these algorithms. Among the 100 cases of HCC, 37 had genotype B (all subgenotype Ba) and 63 had genotype C (16 subgenotype Ce and 47 subgenotype Cs) HBV infection. In the control group, 51 had genotype B and 49 had genotype C (10 subgenotype Ce and 39 subgenotype Cs) HBV infection. Genomic algorithms associated with HCC were derived based on genotype/subgenotype-specific mutations. In genotype B HBV, mutations C1165T, A1762T and G1764A, T2712C/A/G, and A/T2525C were associated with HCC. HCC-related mutations T31C, T53C, and A1499G were associated with HBV subgenotype Ce, and mutations G1613A, G1899A, T2170C/G, and T2441C were associated with HBV subgenotype Cs. Amino acid changes caused by these mutations were found in the X, envelope, and precore/core regions in association with HBV genotype B, Ce, and Cs, respectively. In conclusion, infections with different genotypes of HBV (B, Ce, and Cs) carry different genomic markers for HCC at different parts of the HBV genome. Different HBV genotypes may have different virologic mechanisms of hepatocarcinogenesis.
Analysis of the Evolutionary Forces in an Immunodominant CD8 Epitope in Hepatitis C Virus at a Population Level
Authors: Neumann-Haefelin Christoph , Frick David N. , Wang Jing Jing , Pybus Oliver G. , Salloum Shadi , Narula Gagandeep S. , Eckart Anna , Biezynski Andrea , Eiermann Thomas , Klenerman Paul , Viazov Sergei , Roggendorf Michael , Thimme Robert , Reiser Markus , Timm Jörg
Published: January 2008

Failure of the adaptive immune response to control infection with the hepatitis C virus (HCV) can result from mutational escape in targeted T-cell epitopes. Recent studies suggest that T-cell immune pressure is an important factor in the evolution of the nonstructural proteins in HCV. The aim of this study was to characterize the forces that contribute to viral evolution in an HLA-A*01-restricted epitope in HCV NS3. This epitope represents a potentially attractive target for vaccination strategies since it is conserved across all genotypes. In our cohort of subjects with chronic HCV infection (genotype 1b or 3a), it is a frequently recognized CD8 epitope in HLA-A*01-positive subjects. Viral sequence data reveal that an escape variant is the dominant residue in both genotypes. The predominant Y1444F substitution seemingly impairs binding to the HLA-A*01 molecule, which may have an important impact on the ability to prime a functional CD8 response upon infection. Interestingly, a case of evolution toward the prototype sequence was observed during chronic infection, possibly because the helicase activity of the protein containing the Y1444F substitution is reduced compared to the prototype sequence. Comparison of HCV sequences from Asia and Europe suggests that the frequency of the HLA-A*01 allele in a population may influence the frequency of the escape variant in circulating strains. These data suggest a complex interaction of multiple forces shaping the evolution of HCV in which immune pressure both within the individual and also at the population level in addition to functional constraints are important contributing factors.
The Full-Length Protein Encoded by Human Cytomegalovirus Gene UL117 Is Required for the Proper Maturation of Viral Replication Compartments
Authors: Qian Zhikang , Xuan Baoqin , Hong Te Tee , Yu Dong
Published: January 2008

Previously, two large-scale mutagenic analyses showed that mutations in the human cytomegalovirus (HCMV) gene UL117 resulted in a defect in virus growth in fibroblasts. Early transcriptional analyses have revealed several mRNAs from the UL119-UL115 region; however, specific transcripts encoding UL117-related proteins have not been identified. In this study, we identified two novel transcripts arising from the UL117 gene locus, and we reported that the UL117 open reading frame encoded the full-length protein pUL117 (45 kDa) and the shorter isoform pUL117.5 (35 kDa) as the result of translation initiation at alternative in-frame ATGs. Both proteins were expressed with early kinetics, but pUL117 accumulated at a lower abundance relative to that of pUL117.5. During HCMV infection, both proteins localized predominantly to the nucleus, and the major fraction of pUL117 localized in viral nuclear replication compartments. We constructed mutant HCMV viruses in which the entire UL117 coding sequence was deleted or the expression of pUL117 was specifically abrogated. The growth of mutant viruses was significantly attenuated, indicating that pUL117 was required for efficient virus infection in fibroblasts. Cells infected with the pUL117-deficient mutant virus accumulated representative viral immediate-early proteins and early proteins normally. In the absence of pUL117, the accumulation of replicating viral DNA was reduced by no more than twofold at early times and was indistinguishable from that of the wild type at 72 h postinfection. Strikingly, there was a 12- to 24-h delay in the development of nuclear replication compartments and a marked delay in the expression of late viral proteins. We conclude that pUL117 acts to promote the development of nuclear replication compartments to facilitate viral growth.
Polypyrimidine Tract Binding Protein Induces Human Papillomavirus Type 16 Late Gene Expression by Interfering with Splicing Inhibitory Elements at the Major Late 5′ Splice Site, SD3632
Authors: Somberg Monika , Zhao Xiaomin , Fröhlich Monika , Evander Magnus , Schwartz Stefan
Published: January 2008

We have initiated a screen for cellular factors that can induce human papillomavirus type 16 (HPV-16) late gene expression in human cancer cells. We report that the overexpression of polypyrimidine tract binding protein (PTB), also known as heterologous nuclear ribonucleoprotein I (hnRNP I), induces HPV-16 late gene expression in cells transfected with subgenomic HPV-16 plasmids or with full-length HPV-16 genomes and in persistently HPV-16-infected cells. In contrast, other hnRNPs such as hnRNP B1/A2, hnRNP F, and hnRNP Q do not induce HPV-16 late gene expression. PTB activates SD3632, the only 5′ splice site on the HPV-16 genome that is used exclusively by late mRNAs. PTB interferes with splicing inhibitory sequences located immediately upstream and downstream of SD3632, thereby activating late gene expression. One AU-rich PTB-responsive element was mapped to a 198-nucleotide sequence located downstream of SD3632. The deletion of this element induced HPV-16 late gene expression in the absence of PTB. Our results suggest that the overexpression of PTB interferes with cellular factors that interact with the inhibitory sequences. One may speculate that an increase in PTB levels or a reduction in the concentration of a PTB antagonist is required for the activation of HPV-16 late gene expression during the viral life cycle.
Electron Cryomicroscopy Reveals Different F1+F2 Protein States in Intact Parainfluenza Virions
Authors: Ludwig Kai , Schade Boris , Böttcher Christoph , Korte Thomas , Ohlwein Nina , Baljinnyam Bolormaa , Veit Michael , Herrmann Andreas
Published: January 2008

Electron cryomicrographs of intact parainfluenza virus 5 (PIV5) virions revealed two different surface structures, namely, a continuous layer and distinct individual spikes. The structure of these spikes reconstructed from intact virions was compared with known F ectodomain structures and was found to be different from the prefusion PIV5 F0 structure but, surprisingly, very similar to the human PIV3 F postfusion structure. Hence, we conclude that the individual F1+F2 spikes in intact PIV5 virions also correspond to the postfusion state. Since the observed fusion activity of PIV5 virions has to be associated with prefusion F1+F2 proteins, they have necessarily to be localized in the continuous surface structure. The data therefore strongly suggest that the prefusion state of the F1+F2 protein requires stabilization, most probably by the association with hemagglutinin-neuraminidase. The conversion of F1+F2 proteins from the prefusion toward the postfusion state while embedded in the virus membrane is topologically difficult to comprehend on the basis of established models and demands reconsideration of our current understanding.
Herpes Simplex Virus ICP27 Increases Translation of a Subset of Viral Late mRNAs
Authors: Fontaine-Rodriguez Errin C. , Knipe David M.
Published: January 2008

The herpes simplex virus (HSV) ICP27 immediate-early protein plays an essential role in the expression of viral late genes. ICP27 is a multifunctional protein and has been reported to regulate multiple steps of mRNA synthesis and processing, including transcription, splicing, and nuclear export. Recently, ICP27 was reported to interact with translation factors and to stimulate translation of the viral late mRNA encoding VP16. We examined the effects of ICP27 on accumulation, nuclear export, and translation of HSV 1 (HSV-1) late mRNAs encoding VP16, ICP5, and gD. We confirm here that ICP27 stimulates translation of VP16 mRNA as well as an additional HSV-1 late ICP5 mRNA. The data presented here demonstrate that translation levels of both VP16 and ICP5 mRNA is reduced during infections with the ICP27-null virus mutant
d
27-1, and with ICP27 C-terminal deletion mutant viruses
n
406 and
n
504, compared to wild-type virus. In contrast, the translation of gD mRNA is not affected by the presence of ICP27 during infection. These data demonstrate that ICP27 functions to increase the translation levels of a subset of HSV-1 late genes, and this function requires the C terminus of ICP27.
Simian Immunodeficiency Virus SIVagm Dynamics in African Green Monkeys
Authors: Pandrea Ivona , Ribeiro Ruy M. , Gautam Rajeev , Gaufin Thaidra , Pattison Melissa , Barnes Mary , Monjure Christopher , Stoulig Crystal , Dufour Jason , Cyprian Wayne , Silvestri Guido , Miller Michael D. , Perelson Alan S. , Apetrei Cristian
Published: January 2008

The mechanisms underlying the lack of disease progression in natural simian immunodeficiency virus (SIV) hosts are still poorly understood. To test the hypothesis that SIV-infected African green monkeys (AGMs) avoid AIDS due to virus replication occurring in long-lived infected cells, we infected six animals with SIVagm and treated them with potent antiretroviral therapy [ART; 9-R-(2-phosphonomethoxypropyl) adenine (tenofovir) and beta-2,3-dideoxy-3-thia-5-fluorocytidine (emtricitabine)]. All AGMs showed a rapid decay of plasma viremia that became undetectable 36 h after ART initiation. A significant decrease of viral load was observed in peripheral blood mononuclear cells and intestine. Mathematical modeling of viremia decay post-ART indicates a half-life of productively infected cells ranging from 4 to 9.5 h, i.e., faster than previously reported for human immunodeficiency virus and SIV. ART induced a slight but significant increase in peripheral CD4+T-cell counts but no significant changes in CD4+T-cell levels in lymph nodes and intestine. Similarly, ART did not significantly change the levels of cell proliferation, activation, and apoptosis, already low in AGMs chronically infected with SIVagm. Collectively, these results indicate that, in SIVagm-infected AGMs, the bulk of virus replication is sustained by short-lived cells; therefore, differences in disease outcome between SIVmac infection of macaques and SIVagm infection of AGMs are unlikely due to intrinsic differences in the in vivo cytopathicities between the two viruses.
Molecular Characterization of a Subgroup Specificity Associated with the Rotavirus Inner Capsid Protein VP2
Authors: McDonald Sarah M. , Patton John T.
Published: January 2008

Group A rotaviruses are classified into serotypes, based on the reactivity pattern of neutralizing antibodies to VP4 and VP7, as well as into subgroups (SGs), based on non-neutralizing antibodies directed against VP6. The inner capsid protein (VP2) has also been described as a SG antigen; however, little is known regarding the molecular determinants of VP2 SG specificity. In this study, we characterize VP2 SGs by correlating genetic markers with the immunoreactivity of the SG-specific monoclonal antibody (YO-60). Our results show that VP2 proteins similar in sequence to that of the prototypic human strain Wa are recognized by YO-60, classifying them as VP2 SG-II. In contrast, proteins not bound by YO-60 are similar to those of human strains DS-1 or AU-1 and represent VP2 SG-I. Using a mutagenesis approach, we identified residues that determine recognition by either YO-60 or the group A-specific VP2 monoclonal antibody (6E8). We found that YO-60 binds to a conformationally dependent epitope that includes Wa VP2 residue M328. The epitope for 6E8 is also contingent upon VP2 conformation and resides within a single region of the protein (Wa VP2 residues A440 to T530). Using a high-resolution structure of bovine rotavirus double-layered particles, we predicted these epitopes to be spatially distinct from each other and located on opposite surfaces of VP2. This study reveals the extent of genetic variation among group A rotavirus VP2 proteins and illuminates the molecular basis for a previously described SG specificity associated with the rotavirus inner capsid protein.
Stabilized Binding of TBP to the TATA Box of Herpes Simplex Virus Type 1 Early (tk) and Late (gC) Promoters by TFIIA and ICP4
Authors: Zabierowski Susan E. , DeLuca Neal A.
Published: January 2008

We have recently shown that ICP4 has a differential requirement for the general transcription factor TFIIA in vitro (S. Zabierowski and N. DeLuca, J. Virol. 78:6162-6170, 2004). TFIIA was dispensable for ICP4 activation of a late promoter (gC) but was required for the efficient activation of an early promoter (tk). An intact INR element was required for proficient ICP4 activation of the late promoter in the absence of TFIIA. Because TFIIA is known to stabilize the binding of both TATA binding protein (TBP) and TFIID to the TATA box of core promoters and ICP4 has been shown to interact with TFIID, we tested the ability of ICP4 to stabilize the binding of either TBP or TFIID to the TATA box of representative early, late, and INR-mutated late promoters (tk, gC, and gC8, respectively). Utilizing DNase I footprinting analysis, we found that ICP4 was able to facilitate TFIIA stabilized binding of TBP to the TATA box of the early tk promoter. Using mutant ICP4 proteins, the ability to stabilize the binding of TBP to both the wild-type and the INR-mutated gC promoters was located in the amino-terminal region of ICP4. When TFIID was substituted for TBP, ICP4 could stabilize the binding of TFIID to the TATA box of the wild-type gC promoter. ICP4, however, could not effectively stabilize TFIID binding to the TATA box of the INR-mutated late promoter. The additional activities of TFIIA were required to stabilize the binding of TFIID to the INR-mutated late promoter. Collectively, these data suggest that TFIIA may be dispensable for ICP4 activation of the wild-type late promoter because ICP4 can substitute for TFIIA's ability to stabilize the binding of TFIID to the TATA box. In the absence of a functional INR, ICP4 can no longer stabilize TFIID binding to the TATA box of the late promoter and requires the additional activities of TFIIA. The stabilized binding of TFIID by TFIIA may in turn allow ICP4 to more efficiently activate transcription from non-INR containing promoters.
Novel Mammalian Herpesviruses and Lineages within the
Gammaherpesvirinae
: Cospeciation and Interspecies Transfer
Authors: Ehlers Bernhard , Dural Güzin , Yasmum Nezlisah , Lembo Tiziana , de Thoisy Benoit , Ryser-Degiorgis Marie-Pierre , Ulrich Rainer G. , McGeoch Duncan J.
Published: January 2008

Novel members of the subfamily
Gammaherpesvirinae
, hosted by eight mammalian species from six orders (Primates, Artiodactyla, Perissodactyla, Carnivora, Scandentia, and Eulipotyphla), were discovered using PCR with pan-herpesvirus DNA polymerase (DPOL) gene primers and genus-specific glycoprotein B (gB) gene primers. The gB and DPOL sequences of each virus species were connected by long-distance PCR, and contiguous sequences of approximately 3.4 kbp were compiled. Six additional gammaherpesviruses from four mammalian host orders (Artiodactyla, Perissodactyla, Primates, and Proboscidea), for which only short DPOL sequences were known, were analyzed in the same manner. Together with available corresponding sequences for 31 other gammaherpesviruses, alignments of encoded amino acid sequences were made and used for phylogenetic analyses by maximum-likelihood and Bayesian Monte Carlo Markov chain methods to derive a tree which contained two major loci of unresolved branching details. The tree was rooted by parallel analyses that included alpha- and betaherpesvirus sequences. This gammaherpesvirus tree contains 11 major lineages and presents the widest view to date of phylogenetic relationships in any subfamily of the
Herpesviridae
, as well as the most complex in the number of deep lineages. The tree's branching pattern can be interpreted only in part in terms of the cospeciation of virus and host lineages, and a substantial incidence of the interspecies transfer of viruses must also be invoked.
Synthesis of N-[(3-Amino-1,2-dicarba-closo-dodecaboran-1-yl)acetyl] Derivatives of α-Amino Acids
Authors: Levit Galina L. , Krasnov Victor P. , Gruzdev Dmitriy A. , Demin Alexander M. , Bazhov Iliya V. , Sadretdinova Liliya Sh. , Olshevskaya Valentina A. , Kalinin Valery N. , Cheong Chan Seong , Chupakhin Oleg N. , Charushin Valery N.
Published: January 2008

The N-[(3-amino-1,2-dicarba-closo-dodecaboran-1-yl)acetyl] derivatives of α-amino acids were prepared starting from N-protected (Ac, Form, Bz, and Boc) 3-amino-1-(carboxymethyl)-o-carboranes and alkyl esters of natural α-amino acids using the carbodiimide method of coupling and removing the ester groups. All the amides obtained were diastereoisomeric mixtures. Some diastereoisomers were separated and the assignment of the absolute configuration of aminocarborane fragments was performed by X-ray crystallography.
Boronated Conjugates of Protohemin IX with L-Amino Acids: Synthesis and Antitumor Activity
Authors: Olshevskaya Valentina A. , Savchenko Arina N. , Gorshkov Alexander Yu. , Luzgina Valentina N. , Tatarskii Victor V. , Kononova Elena G. , Cheong Chan Seong , Kalinin Valery N. , Shtil Alexander A.
Published: January 2008

We report the synthesis of novel conjugates of protohemin IX with neutral and anionic boron polyhedra and L-amino acids. The amino acids are linked to the porphyrin macrocycle via the amide or ester bond. The serine containing boronated protohemin was the most cytotoxic for K562 human leukemia cell line. This compound interacted with double-stranded DNA in vitro and caused apoptosis of tumor cells including those that are resistant to several chemotherapeutic drugs.
Study of Proton-Deuterium Exchange in Ten-Vertex Boron Hydrides
Authors: Sivaev Igor B. , Bragin Vikentii I. , Prikaznov Alexander V. , Petrovskii Pavel V. , Bregadze Vladimir I. , Filippov Oleg A. , Teplinskaya Tatyana A. , Titov Alexei A. , Shubina Elena S.
Published: January 2008

The effect of electron-donating and electron-withdrawing substituents on the proton-deuterium exchange in derivatives of the closo-decaborate anion in methanol-d4 was studied. Introduction of the electron-donating hydroxy (alkoxy) group into the apical position of the boron cage strongly promotes the H-D exchange at the antipodal apical vertex, whereas introduction of the electron-withdrawing diazonium group stops the H-D exchange completely. The general order of the proton-deuterium exchange in equatorially-substituted derivatives [2-B10H9R]n- is 10 > 1 >> 7,8 > 4 > 3,5 ≈ 6,9. Formation of dihydrogen bonds between 1- and 2-hydroxy derivatives of the closo-decaborate anion and alcohols was investigated and their possible role in the H-D exchange was discussed.
Pain relief after intratendinous injections in patients with tennis elbow: results of a randomised study
Authors: Zeisig E , Fahlström M , Öhberg L , Alfredson H
Published: January 2008

Background:

“Tennis elbow” is a difficult condition to treat. Ultrasonography (US) and colour Doppler (CD) guided injections with polidocanol targeting the area with increased blood flow in the extensor origin have shown promising clinical results.

Objective:

To evaluate and compare effects of US and CD guided intratendinous injections with sclerosing polidocanol and a local anaesthetic (lidocaine + epinephrine), in patients with tennis elbow.

Design:

Prospective, randomised, controlled, double-blind, crossover study.

Setting:

Sports Medicine Unit, Umeå University.

Patients:

32 patients (36 elbows), age range 27 to 66 years, with a long duration of elbow pain diagnosed as tennis elbow, were included in the study. All patients were followed up 3 and 12 months after treatment. Two patients were excluded due to other interventions during the study.

Interventions:

One US and CD guided injection with the sclerosing agent polidocanol (group 1) or the local anaesthetic lidocaine plus epinephrine (group 2). At the 3 month follow-up, additional injections with polidocanol were offered to both groups (crossover for group 2).

Main outcome measures:

Satisfaction with treatment (Yes/No), elbow pain during activity (visual analogue scale), and maximum voluntary grip strength.

Results:

There were no significant (p<0.05) differences in the outcome between group 1 and group 2. In both groups, there was a significantly lower VAS at the 3-month and 12-month follow-ups, and grip strength was significantly higher at the 12-month follow-up.

Conclusions:

US and CD guided intratendinous injections gave pain relief in patients with tennis elbow. Polidocanol and lidocaine plus epinephrine injections gave similar results.
Mapping tobacco industry strategies in South East Asia for action planning and surveillance
Authors: Stillman F , Hoang M , Linton R , Ritthiphakdee B , Trochim W
Published: January 2008

Objective:

To develop a comprehensive conceptual framework of tobacco industry tactics in four countries in South East Asia for the purpose of: (1) generating consensus on key areas of importance and feasibility for regional and cross country tobacco industry monitoring and surveillance; (2) developing measures to track and monitor the effects of the tobacco industry and to design counterstrategies; and (3) building capacity to improve tobacco control planning in the participating countries.

Design:

A structured conceptualisation methodology known as concept mapping was used. The process included brainstorming, sorting and rating of statements describing industry activities. Statistical analyses used multidimensional scaling and cluster analysis. Interpretation of the maps was participatory, using regional tobacco control researchers, practitioners, and policy makers during a face to face meeting.

Participants:

31 participants in this study come from the four countries represented in the project along with six people from the Johns Hopkins Blomberg School of Public Health.

Conclusions:

The map shows eight clusters of industry activities within the four countries. These were arranged into four general sectors: economics, politics, public relations and deception. For project design purposes, the map indicates areas of importance and feasibility for monitoring tobacco industry activities and serves as a basis for an initial discussion about action planning. Furthermore, the development of the map used a consensus building process across different stakeholders or stakeholder agencies and is critical when developing regional, cross border strategies for tracking and surveillance.
New genera of Paleogene fungal spores
Authors: Elsik William C. , Jansonius Jan
Published: January 2008

Ctenosporites, Granatisporites, and Pesavis are described as new form genera of fossil fungal spores and spore-like fossils; Striadiporites and Pluricellaesporites are emended. Pesavis and Ctenosporites are geographically restricted to the northwest Pacific and Arctic region. Granatisporites is described to facilitate the classification of fungal spore types ubiquitous over at least the Western Hemisphere.
Lipid content of cured tobacco
Authors: Wassef Momtaz K. , Hendrix James W.
Published: January 2008

Samples from cured burley and flue-cured tobacco were examined for total lipid content and for lipid composition of fractionated lipid classes. Cured burley tobacco contained 6–8% lipids compared with 14–15% in cured flue-cured tobacco. Neutral lipids constituted 70–80% of burley lipids but only half the flue-cured lipids; the latter had 75% more neutral lipids than the former. Flue-cured tobacco contained considerably more (5–10 times) medium- to high-polarity lipids than burley. Stalk position had only a minor effect on the lipid content of both tobacco types.
Phenotypic flexibility and genetic adaptation along a gradient of secondary forest succession in the grass Danthonia spicata
Authors: Scheiner Samuel M. , Teeri James A.
Published: January 2008

Populations of Danthonia spicata were studied from sites of ages 0, 26, 32, 44, and 69 years after fire in the aspen–pine forests of northern lower Michigan. Along this gradient the environment changes from unshaded and dry to a shaded, moist pine and hardwood forest. Greenhouse treatments and transplant gardens were used to investigate the extent to which phenotypic flexibility and genetic adaptation were responsible for the persistence of D. spicata across this light and soil moisture gradient. With regard to phenotypic flexibility, we found that individual plants of D. spicata can grow and reproduce in light levels lower than those found at any site in the field. The populations were genetically distinct from each other but the differences were small relative to the range of phenotypic flexibility. Some populations and individuals performed better under high light conditions and all individuals performed equally poorly under low light conditions. A multivariate analysis suggests that genetic drift may have been more important than selection in differentiating the populations. Phenotypic flexibility was shown to be more important than genetic adaptation in explaining the persistence of D. spicata along the successional gradient.
Effects of frost hardening on photosynthetic quantum yield, chlorophyll organization, and energy distribution between the two photosystems in Scots pine
Authors: Öquist Gunnar , Strand Martin
Published: January 2008

Seedlings of Scots pine (Pinus sylvestris L.), with only primary needles, were frost hardened under a photoperiod of 8 h and a temperature of 4 °C for 6–9 weeks. The effects of frost hardening were studied on (i) the photosynthetic efficiency as defined by the quantum yield of CO2 uptake under light-limiting conditions, (ii) the energy partitioning between the two photosystems as analyzed by 77 K fluorescence spectroscopy, and (iii) the distribution of solubilized chlorophyll–protein complexes after electrophoretic separation. It was found that frost hardening had no significant effects either on the photosynthetic quantum yield measured at 23–25 °C or on the energy distribution between the two photosystems. Despite these findings, frost hardening affected the chlorophyll organization so that the proportion of aggregated complexes such as chlorophyll–protein 1a and the dimeric form of light-harvesting chlorophyll–protein decreased. Frost hardening also decreased the amount of chlorophyll–protein a and increased the amount of free, solubilized chlorophyll in the gel scan profile. From these results it is concluded that frost hardening affects the chemical interactions within the antennae organization of the photosynthetic apparatus but that these changes have no significant effects on the energy distribution between the two photosystems or on the photosynthetic efficiency as defined by the quantum yield for CO2 uptake.
Pyxidiophora lundqvistii n.sp. (Hypomycetales, Ascomycetes)
Authors: Corlett Michael
Published: January 2008

Pyxidiophora lundqvistii n. sp., encountered in a mixed culture with Fusarium poae (Peck) Wollenw. isolated from seeds of Triticum aestivum L. (cv. Opal), is described, illustrated, and compared with Pyxidiophora asterophora (Tul.) Lindau, the type species. The ascospores of P. lundqvistii are uniseptate, fusiform, basally apiculate, hyaline, and 20–30 × 3–3.5 μm. At maturity, the wall on one side of the ascospore often swells, increasing the ascospore width to 5 μm. The ascospores lack a subapical pigment spot or other zones of pigmentation common to some species of Pyxidiophora. Pyxidiophora lundqvistii is distinguished from other species in the genus principally by its shorter and narrower ascospores and by its small perithecia.
Competitive interactions of ectomycorrhizal mycobionts under field conditions
Authors: McAfee B. J. , Fortin J. A.
Published: January 2008

A rapid field method to evaluate the competitive performance of selected ectomycorrhizal isolates is presented. Ectomycorrhizal jack pine seedlings and noninoculated controls produced in growth pouches were outplanted in diverse stations 1 month after inoculation. Photographs taken prior to outplanting and at the time of excavation permitted comparative observations of mycorrhizal development along each lateral root of individual seedlings. Nonmycorrhizal control seedlings showed 0, 20, 20, and 76% mycorrhizal development at the sterilized denuded, unsterilized denuded, burned, and undisturbed jack pine stand stations, respectively. To evaluate the postplanting performance of each isolate tested, an index of colonization and an index of competition were established. Laccaria bicolor was the best colonizer at all stations except the undisturbed jack pine stand, where Rhizopogon rubescens was the best colonizer and also the most competitive. Pisolithus tinctorius was not competitive with the indigenous mycota at the burned or the undisturbed jack pine stand stations.
Some ultrastructural aspects of the pollen transmission of barley stripe mosaic virus in barley
Authors: Brlansky Ronald H. , Carroll Thomas W. , Zaske Susan K.
Published: January 2008

To study the pollen transmission of barley stripe mosaic virus (BSMV) in barley with the transmission electron microscope, ultrathin sections of ovaries of pollinated pistils were examined. Healthy pistils were cross-pollinated with virus-infected pollen and collected at various intervals of time after pollination. When thin sections of the ovaries were viewed, virus particles were detected in specific sporophytic and gametophytic cells during critical developmental stages of pollination, fertilization, and embryogenesis. Before fertilization, BSMV particles were seen in the pollen tube between the integument and ovary wall, and in pollen tube discharge within the degenerating synergid. During and after fertilization, virus particles were found not only in the pollen tube and its discharge but also in the zygote, endosperm, persistent synergid, and nucellus. During embryogenesis, BSMV particles were very evident in the embryo, integument, and ovary wall. Some particles were scattered throughout the cell cytoplasm, while others were in mono- or multi-layer aggregates within the cytoplasm. Many particles were associated with spindle or cytoplasmic microtubules or with abnormal plastids. The prevalence of virus particles in the cells associated with sexual reproduction suggests that the nucleoprotein particle form of the virus plays some role in the pollen transmission of BSMV in barley.
Growth characteristics of rough fescue (Festuca scabrella var. campestris) after three years of repeated harvesting at scheduled frequencies and heights
Authors: Willms Walter D. , Fraser Joanna
Published: January 2008

A study was made in the rough fescue grasslands of southwestern Alberta to determine the growth response of rough fescue (Festuca scabrella var. campestris Rydb.) to five cutting frequencies and three cutting heights after 3 years of repeated treatments. The same plants were cut either 1, 2, 4, 8, or 16 times over a 16-week period beginning in mid-May, at 16-, 8-, 4-, 2-, or 1-week intervals, respectively, and at heights of either 5, 10, or 15 cm above ground level. After 3 years of repeated treatment, dry matter yields, etiolated growth, tiller height, tiller number, and growth rate decreased with increased cutting frequency and decreased cutting height. A single harvest at the end of August, cut at a height of 15 cm, produced yields that were similar to previously undisturbed plants. This treatment also produced the maximum sustainable forage yields. The study confirms the high susceptibility of rough fescue to grazing during the growing season and indicates that optimum management should include dormant-season grazing. Key words: defoliation, forage yield, regrowth, etiolated growth, tillers.
Water and nutrient translocation by hyphae of Glomus mosseae
Authors: George Eckhard , Häussler Karl-Uwe , Vetterlein Doris , Gorgus Eva , Marschner Horst
Published: January 2008

To test the ability of vesicular–arbuscular mycorrhizal (VAM) hyphae to take up water, phosphorus, nitrogen, and potassium, mycorrhizal and nonmycorrhizal couchgrass (Agropyron repens) or white clover (Trifolium repens) plants were grown in pots with separated compartments for roots and hyphae growth. Soil solution transfer between compartments was blocked by a 2-mm air gap. Total shoot contents of phosphate and nitrogen, but not of potassium, were higher in mycorrhizal plants with access to the hyphal compartment. Hyphal uptake from the outer compartment accounted for 49% of the total phosphate and 35% of the total nitrogen taken up by mycorrhizal plants. This was associated with depletion of extractable phosphate, [Formula: see text]-nitrogen, and also [Formula: see text]-nitrogen in the soil of the hyphal compartments. In contrast, no difference in water loss from the hyphal compartments was measured by tensiometers under well-watered and water-stress conditions whether hyphae were present or not. Severance of the external hyphae did not affect water loss from the outer compartments. The results show the ability of VAM hyphae to transport considerable quantities of phosphate and nitrogen to the plant from soil zones several centimetres from the root. However, there was no evidence for a significant direct water transport by VAM hyphae to plants. Key words: Agropyron repens (couchgrass), Glomus mosseae, nitrogen, phosphorus, vesicular–arbuscular mycorrhiza, water.
The flagellar apparatus in zoospores of Phytophthora, Pythium, and Halophytophthora
Authors: Barr D. J. S. , Désaulniers N. L.
Published: January 2008

The flagellar apparatuses of 14 species of Phytophthora, 2 of Halophytophthora, and 4 of Pythium are compared in the transmission electron microscope. Except for Phytophthora infestans and Phytophthora mirabilis there were no significant differences in fine structure morphology. There are six flagellar roots: a ribbed triplet consisting of three main microtubules and secondary microtubules; an anterior doublet; a multistranded, band-shaped root of five to nine microtubules; a posterior root of two to four microtubules; and roots consisting of arrays of cytoplasmic microtubules and nuclear-associated microtubules. In P. infestans and P. mirabilis the multistranded root is missing, the posterior root contains five or six microtubules, and the anterior ribbed root contains four main microtubules. The transitional zones in all species are similar. The relationship of the Pythiaceae with other Oomycetes is discussed. Key words: taxonomy, phytogeny, cytology, Oomycetes, Pythiaceae.
Bryophytes of Mingan Archipelago National Park Reserve, Quebec: a boreal flora with arctic and alpine components
Authors: Belland René J. , Schofield W. B. , Hedderson Terry A.
Published: January 2008

The Mingan Archipelago National Park Reserve has a bryophyte flora of 302 species, including 233 mosses and 69 hepatics. This includes about 45% of the known bryoflora of the Gulf of St. Lawrence region. The park bryophyte flora is dominated by boreal species and has lesser representation of temperate and arctic-alpine species. About 73% of the park flora belongs to the boreal distributional element and two-thirds of these species are circumboreal or widespread in the boreal biome of the northern hemisphere. The flora is youthful and all species have colonized the islands within the last 7000 years. Most of the Mingan species probably originated from populations that survived during the last glaciation in sites south of the icesheet margin. However, many species could have migrated to the islands from nearby réfugia within the Gulf of St. Lawrence region where they were able to survive the glaciation in situ. These refugial species include many of the arctic-alpine and montane species found in the park. Key words: Mingan Islands, bryophytes, diversity, glaciation.
Responses of two hybrid Populus clones to flooding, drought, and nitrogen availability. I. Morphology and growth
Authors: Liu Zhijun , Dickmann Donald I.
Published: January 2008

Repeated progressive drought and flooding stress were imposed on hybrid poplar clones Populus × euramericana 'Eugenei', and Populus tristis × Populus balsamifera ‘Tristis’ grown in pots in a greenhouse under two nitrogen levels. In both clones the rate of leaf initiation was promoted only in high-N plants subjected to minimum water stress. Water stress alone did not retard the rate of leaf initiation, but it significantly reduced leaf expansion of 'Eugenei', whereas only flooding led to smaller leaves in 'Tristis'. The addition of N stimulated leaf expansion, leaf chlorophyll and N concentrations, and leaf and stem biomass production across soil moisture levels, but the greatest effect of N was associated with minimum water stress. High N altered carbon allocation towards the aboveground portions, leading to lower root to shoot ratios. High N also appeared to stimulate initiation of fine roots. Soil moisture determined the amount of biomass that accumulated in roots, with highest root production in well-watered pots and lowest in flooded pots, with the droughted treatment in between. Leaves became thinner as soil moisture decreased from flooding. Stem biomass of 'Tristis' declined more under flooding than under drought, whereas 'Eugenei' displayed a greater reduction of stem biomass in droughty than in flooded soil. Key words: water stress, nitrogen, leaf and root morphology, root to shoot ratio, biomass, Populus, flooding.