641 research outputs found

    A characterization of compact complex tori via automorphism groups

    Full text link
    We show that a compact Kaehler manifold X is a complex torus if both the continuous part and discrete part of some automorphism group G of X are infinite groups, unless X is bimeromorphic to a non-trivial G-equivariant fibration. Some applications to dynamics are given.Comment: title changed, to appear in Math. An

    Singular del Pezzo surfaces that are equivariant compactifications

    Full text link
    We determine which singular del Pezzo surfaces are equivariant compactifications of G_a^2, to assist with proofs of Manin's conjecture for such surfaces. Additionally, we give an example of a singular quartic del Pezzo surface that is an equivariant compactification of a semidirect product of G_a and G_m.Comment: 14 pages, main result extended to non-closed ground field

    Evidence of different climatic adaptation strategies in humans and non-human primates

    Get PDF
    Abstract: To understand human evolution it is critical to clarify which adaptations enabled our colonisation of novel ecological niches. For any species climate is a fundamental source of environmental stress during range expansion. Mammalian climatic adaptations include changes in size and shape reflected in skeletal dimensions and humans fit general primate ecogeographic patterns. It remains unclear however, whether there are also comparable amounts of adaptation in humans, which has implications for understanding the relative importance of biological/behavioural mechanisms in human evolution. We compare cranial variation between prehistoric human populations from throughout Japan and ecologically comparable groups of macaques. We compare amounts of intraspecific variation and covariation between cranial shape and ecological variables. Given equal rates and sufficient time for adaptation for both groups, human conservation of non-human primate adaptation should result in comparable variation and patterns of covariation in both species. In fact, we find similar amounts of intraspecific variation in both species, but no covariation between shape and climate in humans, contrasting with strong covariation in macaques. The lack of covariation in humans may suggest a disconnect in climatic adaptation strategies from other primates. We suggest this is due to the importance of human behavioural adaptations, which act as a buffer from climatic stress and were likely key to our evolutionary success

    Transfer pricing: strategies, practices, and tax minimization

    Full text link
    Using a survey of tax executives from multinational corporations, we document that some firms set their transfer pricing strategy to minimize tax payments, but more firms focus on tax compliance. We estimate that a firm focusing on minimizing taxes has a GAAP effective tax rate that is 6.6 percentage points lower and generates about $43 million more in tax savings, on average, than a firm focusing on tax compliance. Available COMPUSTAT data on sample firms confirm our survey‐based inferences. We also find that transfer pricing‐related tax savings are greater when higher foreign income, tax haven use, and R&D activities are combined with a tax minimization strategy. Finally, compliance‐focused firms report lower FIN 48 tax reserves than tax‐minimizing firms, consistent with the former group using less uncertain transfer pricing arrangements. Collectively, our study provides direct evidence that multinational firms have differing internal priorities for transfer pricing, and that these differences are strongly related to the taxes reported by these firms.First author draf

    Evidence of different climatic adaptation strategies in humans and non-human primates

    Get PDF
    To understand human evolution it is critical to clarify which adaptations enabled our colonisation of novel ecological niches. For any species climate is a fundamental source of environmental stress during range expansion. Mammalian climatic adaptations include changes in size and shape reflected in skeletal dimensions and humans fit general primate ecogeographic patterns. It remains unclear however, whether there are also comparable amounts of adaptation in humans, which has implications for understanding the relative importance of biological/behavioural mechanisms in human evolution. We compare cranial variation between prehistoric human populations from throughout Japan and ecologically comparable groups of macaques. We compare amounts of intraspecific variation and covariation between cranial shape and ecological variables. Given equal rates and sufficient time for adaptation for both groups, human conservation of non-human primate adaptation should result in comparable variation and patterns of covariation in both species. In fact, we find similar amounts of intraspecific variation in both species, but no covariation between shape and climate in humans, contrasting with strong covariation in macaques. The lack of covariation in humans may suggest a disconnect in climatic adaptation strategies from other primates. We suggest this is due to the importance of human behavioural adaptations, which act as a buffer from climatic stress and were likely key to our evolutionary success

    Outcome Measures in Rheumatology - Interventions for medication Adherence (OMERACT-Adherence) Core Domain Set for Trials of Interventions for Medication Adherence in Rheumatology: 5 Phase Study Protocol

    Get PDF
    Background: Over the last 20 years, there have been marked improvements in the availability of effective medications for rheumatic conditions such as gout, osteoporosis and rheumatoid arthritis (RA), which have led to a reduction in disease flares and the risk of re-fracture in osteoporosis, and the slowing of disease progression in RA. However, medication adherence remains suboptimal, as treatment regimens can be complex and difficult to continue long term. Many trials have been conducted to improve adherence to medication. Core domains, which are the outcomes of most relevance to patients and clinicians, are a pivotal component of any trial. These core domains should be measured consistently, so that all relevant trials can be combined in systematic reviews and meta-analyses to reach conclusions that are more valid. Failure to do this severely limits the potential for trial-based evidence to inform decisions on how to support medication adherence. The Outcome Measures in Rheumatology (OMERACT) - Interventions for Medication Adherence study by the OMERACT-Adherence Group aims to develop a core domain set for interventions that aim to support medication adherence in rheumatology. Methods/design: This OMERACT-Adherence study has five phases: (1) a systematic review to identify outcome domains that have been reported in interventions focused on supporting medication adherence in rheumatology; (2) semi-structured stakeholder interviews with patients and caregivers to determine their views on the core domains; (3) focus groups using the nominal group technique with patients and caregivers to identify and rank domains that are relevant to them, including the reasons for their choices; (4) an international three-round modified Delphi survey involving patients with diverse rheumatic conditions, caregivers, health professionals, researchers and other stakeholders to develop a preliminary core domain set; and (5) a stakeholder workshop with OMERACT members to review, vote on and reach a consensus on the core domain set for interventions to support medication adherence in rheumatology. Discussion: Establishing a core domain set to be reported in all intervention studies undertaken to support patients with medication adherence will enhance the relevance and the impact of these results and improve the lives of people with rheumatic conditions.The OMERACT-Adherence Group receives funding from OMERACT, which will be used to support a patient research partner in the OMERACT-Adherence Group to attend the OMERACT conference. OMERACT (http://www.omeract.org, contact: secretariat [email protected]) is the primary sponsor responsible for approving the initiation and overviewing the ongoing progress and management of the study. OMERACT mentors overview the design and conduct of the studies, including the interpretation of data and preparation, and review and approval of manuscripts. The following funding organisations had no role in the design and conduct of the studies; collection, management, analysis and interpretation of the data; or preparation, review or approval of manuscripts. AK is supported by the Arthritis Australia Scholarship funded by the Allan and Beryl Stephens Grant from the Estate of the Late Beryl Stephens. AT is supported by a National Health and Medical Research Council Fellowship (1037162). RC’s employer, the Parker Institute, Bispebjerg, and Frederiksberg Hospital, is supported by a core grant (OCAY-13-309) from the Oak Foundation. Phases 1–3 of the OMERACT-Adherence study were funded by a 2018 Arthritis Australia project grant (major funder), and a private research grant provided by Professor Stephen Hall

    Inhibition of Quorum Sensing-Controlled Virulence Factor Production in Pseudomonas aeruginosa PAO1 by Ayurveda Spice Clove (Syzygium Aromaticum) Bud Extract

    Get PDF
    Quorum sensing controls the virulence determinants in most proteobacteria. In this work, the hexane, chloroform and methanol extracts of an Ayurveda spice, namely clove (Syzygium aromaticum), shown anti-quorum sensing activity. Hexane and methanol extracts of clove inhibited the response of C. violaceum CV026 to exogenously supplied N‐hexanoylhomoserine lactone, in turn preventing violacein production. Chloroform and methanol extracts of clove significantly reduced bioluminescence production by E. coli [pSB1075] grown in the presence of N-(3-oxododecanoyl)-l-homoserine lactone. We demonstrated that clove extract inhibited quorum sensing-regulated phenotypes in Pseudomonas aeruginosa PA01, including expression of lecA::lux (by hexane extract), swarming (maximum inhibition by methanol extract), pyocyanin (maximum inhibition by hexane extract). This study shows that the presence of natural compounds that exhibit anti-quorum sensing activity in the clove extracts may be useful as the lead of anti-infective drugs

    Silencing of genes involved in Anaplasma marginale-tick interactions affects the pathogen developmental cycle in Dermacentor variabilis

    Get PDF
    <p>Abstract</p> <p>Background</p> <p>The cattle pathogen, <it>Anaplasma marginale</it>, undergoes a developmental cycle in ticks that begins in gut cells. Transmission to cattle occurs from salivary glands during a second tick feeding. At each site of development two forms of <it>A. marginale </it>(reticulated and dense) occur within a parasitophorous vacuole in the host cell cytoplasm. However, the role of tick genes in pathogen development is unknown. Four genes, found in previous studies to be differentially expressed in <it>Dermacentor variabilis </it>ticks in response to infection with <it>A. marginale</it>, were silenced by RNA interference (RNAi) to determine the effect of silencing on the <it>A. marginale </it>developmental cycle. These four genes encoded for putative glutathione S-transferase (GST), salivary selenoprotein M (SelM), H+ transporting lysosomal vacuolar proton pump (vATPase) and subolesin.</p> <p>Results</p> <p>The impact of gene knockdown on <it>A. marginale </it>tick infections, both after acquiring infection and after a second transmission feeding, was determined and studied by light microscopy. Silencing of these genes had a different impact on <it>A. marginale </it>development in different tick tissues by affecting infection levels, the densities of colonies containing reticulated or dense forms and tissue morphology. Salivary gland infections were not seen in any of the gene-silenced ticks, raising the question of whether these ticks were able to transmit the pathogen.</p> <p>Conclusion</p> <p>The results of this RNAi and light microscopic analyses of tick tissues infected with <it>A. marginale </it>after the silencing of genes functionally important for pathogen development suggest a role for these molecules during pathogen life cycle in ticks.</p

    Maturation of Streptococcus pneumoniae lipoproteins by a type II signal peptidase is required for ABC transporter function and full virulence

    Get PDF
    Cell surface lipoproteins are important for the full virulence of several bacterial pathogens, including Streptococcus pneumoniae. Processing of prolipoproteins seems to be conserved among different bacterial species, and requires type II signal peptidase (Lsp) mediated cleavage of the N-terminal signal peptide to form the mature lipoprotein. Lsp has been suggested as a target for new antibiotic therapies, but at present there are only limited data on the function of Lsp for Gram-positive bacterial pathogens. We have investigated the function and role during disease pathogenesis of the S. pneumoniae Lsp, which, blast searches suggest, is encoded by the gene Sp0928. Expression of Sp0928 protected Escherichia coli against the Lsp antagonist globomycin, and proteomics and immunoblot analysis demonstrated that deletion of Sp0928 prevented processing of S. pneumoniae prolipoproteins to mature lipoproteins. These data strongly suggest that Sp0928 encodes the S. pneumoniae Lsp. However, immunoblots of membrane-associated proteins, immunoelectron microscopy and flow cytometry assays all confirmed that in the absence of Lsp, immature lipoproteins were still attached to the cell surface. Despite preservation of lipoprotein attachment to the cell membrane, loss of S. pneumoniae Lsp resulted in several phenotypes associated with impaired lipoprotein function and reduced S. pneumoniae replication in animal models of infection

    Maternal LAMP/p55gagHIV-1 DNA Immunization Induces In Utero Priming and a Long-Lasting Immune Response in Vaccinated Neonates

    Get PDF
    Infants born to HIV-infected mothers are at high risk of becoming infected during gestation or the breastfeeding period. A search is thus warranted for vaccine formulations that will prevent mother-to-child HIV transmission. The LAMP/gag DNA chimeric vaccine encodes the HIV-1 p55gag fused to the lysosome-associated membrane protein-1 (LAMP-1) and has been shown to enhance anti-Gag antibody (Ab) and cellular immune responses in adult and neonatal mice; such a vaccine represents a new concept in antigen presentation. In this study, we evaluated the effect of LAMP/gag DNA immunization on neonates either before conception or during pregnancy. LAMP/gag immunization of BALB/c mice before conception by the intradermal route led to the transfer of anti-Gag IgG1 Ab through the placenta and via breastfeeding. Furthermore, there were an increased percentage of CD4+CD25+Foxp3+T cells in the spleens of neonates. When offspring were immunized with LAMP/gag DNA, the anti-Gag Ab response and the Gag-specific IFN-γ-secreting cells were decreased. Inhibition of anti-Gag Ab production and cellular responses were not observed six months after immunization, indicating that maternal immunization did not interfere with the long-lasting memory response in offspring. Injection of purified IgG in conjunction with LAMP/gag DNA immunization decreased humoral and cytotoxic T-cell responses. LAMP/gag DNA immunization by intradermal injection prior to conception promoted the transfer of Ab, leading to a diminished response to Gag without interfering with the development of anti-Gag T- and B-cell memory. Finally, we assessed responses after one intravenous injection of LAMP/gag DNA during the last five days of pregnancy. The intravenous injection led to in utero immunization. In conclusion, DNA vaccine enconding LAMP-1 with Gag and other HIV-1 antigens should be considered in the development of a protective vaccine for the maternal/fetal and newborn periods
    corecore