127 research outputs found

    Additive group actions with finitely generated invariants

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    Local Triviality of Proper Ga Actions

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    AbstractRegular actions of the additive group of complex numbers on complex surfaces and on complex affine space are considered. A proper action on an affine surface admits a geometric quotient which is an affine curve. A proper action on a normal quasiaffine surface is equivariantly trivial. New criteria for local and “global” triviality of proper actions on a complex affine space of arbitrary dimension are presented

    Search for exchange-antisymmetric two-photon states

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    Atomic two-photon J=0 \leftrightarrowJ'=1 transitions are forbidden for photons of the same energy. This selection rule is related to the fact that photons obey Bose-Einstein statistics. We have searched for small violations of this selection rule by studying transitions in atomic Ba. We set a limit on the probability vv that photons are in exchange-antisymmetric states: v<1.2107v<1.2\cdot10^{-7}.Comment: 5 pages, 4 figures, ReVTeX and .eps. Submitted to Phys. Rev. Lett. Revised version 9/25/9

    Description of Goussia kuehae n. sp. (Apicomplexa: Eimeriidae) infecting the Asian seabass, Lates calcarifer (Bloch)(Perciformes: Latidae), cultured in Malaysian fish farms

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    Culturing fishes in marine cages is a rapidly developing area of marine aquaculture. The Asian seabass Lates calcarifer (Bloch) is a fast growing good quality fish that is readily cultured in intensive systems in the South Asian region and in Malaysia in particular. Although several papers have been published to date on viral, bacterial, parasitic and fungal organisms causing diseases in the Asian seabass, the occurrence of a coccidian infection in this species has only recently been recorded. We collected sporulated and unsporulated oo¨cysts of a new species of Goussia Labbe´, 1986, from the mucus covering the epithelium of the intestine of L. calcarifer. This paper provides a description of Goussia kuehae n. sp. Sporulated oo¨cysts of this species are ellipsoidal, 37–40 lm in length and 28–30 lm in width. The ellipsoidal sporocysts are relatively small, 15.2–17 9 5.7–8 lm, and located loosely in the oo¨cyst. There are residual bodies both in the oo¨cysts and the sporocysts. Goussia kuehae n. sp. differs from all known species of Goussia in the large size of the oo¨cysts and in having two types of oo¨cyst residuum

    Do better executive functions buffer the effect of current parental depression on adolescent depressive symptoms?

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    Background Offspring of parents with a history of major depressive disorder (MDD) and especially those exposed to a current episode of parental depression have been found to be at increased risk for developing depression themselves. Exposure to a current parental depressive episode also reduces the efficacy of interventions in high risk or depressed adolescents. This highlights the need to identify protective factors for adolescents exposed to a current parental depressive episode. Executive functions serve as an important cognitive resource, involved in the ability to regulate mood and thoughts and cope with stressful events. This study examined the buffering role of two components of executive functioning, inhibitory control and mental flexibility, in the association between a current parental episode of MDD and adolescent depressive symptoms. Methods A high-risk sample of 288 adolescent offspring of parents with recurrent major depressive disorder completed an Affective Go/No Go and a Verbal Fluency task. Parents and adolescents underwent psychiatric interviews. Results In the presence of a current parental depressive episode in the parent, adolescents with better inhibitory control and mental flexibility had fewer depressive symptoms after controlling for age, gender and IQ. Limitations Participants were the offspring of depressed parents and it is not clear whether the protective effects of executive functioning observed here would generalise to other populations. Conclusions Executive functions may protect against adolescent depression in the presence of a parental depressive episode. It may be beneficial to target executive functions in preventive programs for individuals at high-risk for depression

    Newly established tumourigenic primary human colon cancer cell lines are sensitive to TRAIL-induced apoptosis in vitro and in vivo

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    Most data on the therapeutic potential of tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) as well as resistance to FAS ligand (FASL) in colorectal cancer have come from in vitro studies using cell lines. To gain a clearer understanding about the susceptibility of patient tumours to TRAIL and FASL, we derived primary human cancer epithelial cells from colon cancer patients. Characterisation of primary cultures PAP60 and MIH55 determined their highly proliferating advantage, transforming capability and tumorigenicity in vitro and in vivo. Although FASL treatment appeared to cause little apoptosis only in the PAP60 primary culture, increased apoptosis independent of p53 was observed in both primary PAP60 and MIH55 and control cell lines Caco-2, HT29 and DLD-1 after treatment with SuperKiller TRAIL. Expression analysis of death receptors (DR) in the original parental tumours, the primary cultures before and after engraftment as well as the mouse xenografts, revealed a significant upregulation of both DR4 and DR5, which correlated to differences in sensitivity of the cells to TRAIL-induced apoptosis. Treating patient tumour xenograft/SCID mouse models with Killer TRAIL in vivo suppressed tumour growth. This is the first demonstration of TRAIL-induced apoptosis in characterised tumorigenic primary human cultures (in vitro) and antitumour activity in xenograft models (in vivo)
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