63 research outputs found

    "An effective two dimensionality" cases bring a new hope to the Kaluza-Klein[like] theories

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    One step towards realistic Kaluza-Klein[like] theories and a loop hole through the Witten's "no-go theorem" is presented for cases which we call an effective two dimensionality cases: In d=2d=2 the equations of motion following from the action with the linear curvature leave spin connections and zweibeins undetermined. We present the case of a spinor in d=(1+5)d=(1+5) compactified on a formally infinite disc with the zweibein which makes a disc curved on an almost S2S^2 and with the spin connection field which allows on such a sphere only one massless normalizable spinor state of a particular charge, which couples the spinor chirally to the corresponding Kaluza-Klein gauge field. We assume no external gauge fields. The masslessness of a spinor is achieved by the choice of a spin connection field (which breaks parity), the zweibein and the normalizability condition for spinor states, which guarantee a discrete spectrum forming the complete basis. We discuss the meaning of the hole, which manifests the noncompactness of the space.Comment: 26 pages, 1 figure, an addition which helps to clarify the assumptions and their consequences (the discreteness of spectrum, the massless solution of one handedness,..

    On the origin of families of quarks and leptons - predictions for four families

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    The approach unifying all the internal degrees of freedom--proposed by one of us--is offering a new way of understanding families of quarks and leptons: A part of the starting Lagrange density in d(=1+13), which includes two kinds of spin connection fields--the gauge fields of two types of Clifford algebra objects--transforms the right handed quarks and leptons into the left handed ones manifesting in d=1+3 the Yukawa couplings of the Standard model. We study the influence of the way of breaking symmetries on the Yukawa couplings and estimate properties of the fourth family--the quark masses and the mixing matrix, investigating the possibility that the fourth family of quarks and leptons appears at low enough energies to be observable with the new generation of accelerators.Comment: 31 pages,revte

    Puzzles of Dark Matter - More Light on Dark Atoms?

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    Positive results of dark matter searches in experiments DAMA/NaI and DAMA/LIBRA confronted with results of other groups can imply nontrivial particle physics solutions for cosmological dark matter. Stable particles with charge -2, bound with primordial helium in O-helium "atoms" (OHe), represent a specific nuclear-interacting form of dark matter. Slowed down in the terrestrial matter, OHe is elusive for direct methods of underground Dark matter detection using its nuclear recoil. However, low energy binding of OHe with sodium nuclei can lead to annual variations of energy release from OHe radiative capture in the interval of energy 2-4 keV in DAMA/NaI and DAMA/LIBRA experiments. At nuclear parameters, reproducing DAMA results, the energy release predicted for detectors with chemical content other than NaI differ in the most cases from the one in DAMA detector. Moreover there is no bound systems of OHe with light and heavy nuclei, so that there is no radiative capture of OHe in detectors with xenon or helium content. Due to dipole Coulomb barrier, transitions to more energetic levels of Na+OHe system with much higher energy release are suppressed in the correspondence with the results of DAMA experiments. The proposed explanation inevitably leads to prediction of abundance of anomalous Na, corresponding to the signal, observed by DAMA.Comment: Contribution to Proceedings of XIII Bled Workshop "What Comes beyond the Standard Model?

    Evaluation of the dual mTOR / PI3K inhibitors Gedatolisib (PF-05212384) and PF-04691502 against ovarian cancer xenograft models

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    We are grateful to Wyeth/Pfizer (ONC-EU-150) and to the Scottish Funding Council (SRDG HR07005) for support of this study.This study investigated the antitumour effects of two dual mTOR/PI3K inhibitors, gedatolisib (WYE-129587/PKI-587/PF-05212384) and PF-04691502 against a panel of six human patient derived ovarian cancer xenograft models. Both dual mTOR/PI3K inhibitors demonstrated antitumour activity against all xenografts tested. The compounds produced tumour stasis during the treatment period and upon cessation of treatment, tumours re-grew. In several models, there was an initial rapid reduction of tumour volume over the first week of treatment before tumour stasis. No toxicity was observed during treatment. Biomarker studies were conducted in two xenograft models; phospho-S6 (Ser235/236) expression (as a readout of mTOR activity) was reduced over the treatment period in the responding xenograft but expression increased to control (no treatment) levels on cessation of treatment. Phospho-AKT (Ser473) expression (as a readout of PI3K) was inhibited by both drugs but less markedly so than phospho-S6 expression. Initial tumour volume reduction on treatment and regrowth rate after treatment cessation was associated with phospho-S6/total S6 expression ratio. Both drugs produced apoptosis but minimally influenced markers of proliferation (Ki67, phospho-histone H3). These results indicate that mTOR/PI3K inhibition can produce broad spectrum tumour growth stasis in ovarian cancer xenograft models during continuous chronic treatment and this is associated with apoptosis.Publisher PDFPeer reviewe

    Enhanced Microwave Absorption Properties of Intrinsically Core/shell Structured La0.6Sr0.4MnO3Nanoparticles

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    The intrinsically core/shell structured La0.6Sr0.4MnO3nanoparticles with amorphous shells and ferromagnetic cores have been prepared. The magnetic, dielectric and microwave absorption properties are investigated in the frequency range from 1 to 12 GHz. An optimal reflection loss of −41.1 dB is reached at 8.2 GHz with a matching thickness of 2.2 mm, the bandwidth with a reflection loss less than −10 dB is obtained in the 5.5–11.3 GHz range for absorber thicknesses of 1.5–2.5 mm. The excellent microwave absorption properties are a consequence of the better electromagnetic matching due to the existence of the protective amorphous shells, the ferromagnetic cores, as well as the particular core/shell microstructure. As a result, the La0.6Sr0.4MnO3nanoparticles with amorphous shells and ferromagnetic cores may become attractive candidates for the new types of electromagnetic wave absorption materials

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    Abstract. Gender differences in CAD have been clearly documented, and sex hormones have been recognized to influence the risk of CAD. The cytochrome P450c17α α gene (CYP17) and the CYP19 gene influence concentrations of sex hormones. In this cross-sectional association study we tested the hypothesis whether the T/C polymorphism of the CYP17 gene and the tetranucleotide repeat (TTTA) polymorphism of the CYP19 gene are genetic markers for CAD in Caucasians. The TT genotype of the CYP17 gene polymorphism was not associated with premature CAD in men and women combined (OR 0.9; 95% CI = 0.6-1.4; P = 0.7), in men only (OR 1; 95% CI = 0.6-1.8; P = 0.7), and in women only (OR 0.8; 95% CI = 0.5-1.4; P = 0.4). The tetranucleotide repeat (TTTA) CYP19 gene polymorphism was not associated with premature CAD. Moreover, the genotypes containing the longer alleles (A6 or A7) were not associated with a lower incidence of CAD, and the genotypes containing the shorter alleles (A1 or A2) were not over-represented in the CAD patients. We may conclude that in Caucasian subjects neither the T/C CYP17 gene polymorphism nor the tetranucleotide repeat (TTTA) polymorphism of the CYP19 gene contributes to the genetic susceptibility to CAD, therefore they may not be used as genetic markers for CAD risk assessment. Gender differences in coronary artery disease (CAD) have been clearly documented, and sex hormones have been recognized to influence the risk of developing cardiovascular disease The cytochrome P450c17α gene (CYP17) encodes the cytochrome P450c17α enzyme, which is involved in the formation of precursors of testosterone and oestradiol. The T/C polymorphism of the CYP17 gene creates a recognition site for the MspA1 restriction enzyme and has been used to designate two alleles, A1 (T) and A2 (C). Subjects with the C allele have an additional Sp 1 site, which results in an increased expression of the gene The CYP19 gene encodes the enzyme aromatase (P450aro) that is crucially involved in the production of oestrogens from androgens. In men and postmenopausal women the enzyme aromatase is the main source of circulating oestrogens produced mainly peripherally from androgenic steroids, whereas in premenopausal women the ovary is the main source of circulating oestradiol Associations of the CYP17 and CYP19 polymorphisms are being extensively studied to clarify their role in hormone-related cancers (breast, endometrial, prostate and ovarian cancer), osteoporosis, and hip frac
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