8,939 research outputs found

    Nuclear phenotype changes after heat shock in Panstrongylus megistus (Burmeister)

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    The nuclear phenotypes of Malpighian tubule epithelial cells of male nymphs of the blood-sucking insect, Panstrongylus megistus, subjected to short- and long-duration heat shocks at 40ºC were analyzed immediately after the shock and 10 and 30 days later. Normal nuclei with a usual heterochromatic body as well as phenotypes indicative of survival (unravelled heterochromatin, giants) and death (apoptosis, necrosis) responses were observed in control and treated specimens. However, all nuclear phenotypes, except the normal ones, were more frequent in shocked specimens. Similarly altered phenotypes have also been reported in Triatoma infestans following heat shock, although at different frequencies. The frequency of the various nuclear phenotypes observed in this study suggests that the forms of cell survival observed were not sufficient or efficient enough to protect all of the Malpighian tubule cells from the deleterious effects of stress. In agreement with studies on P. megistus survival following heat shock, only long-duration shock produced strongly deleterious effects.27127

    CP and Lepton-Number Violation in GUT Neutrino Models with Abelian Flavour Symmetries

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    We study the possible magnitudes of CP and lepton-number-violating quantities in specific GUT models of massive neutrinos with different Abelian flavour groups, taking into account experimental constraints and requiring successful leptogenesis. We discuss SU(5) and flipped SU(5) models that are consistent with the present data on neutrino mixing and upper limits on the violations of charged-lepton flavours and explore their predictions for the CP-violating oscillation and Majorana phases. In particular, we discuss string-derived flipped SU(5) models with selection rules that modify the GUT structure and provide additional constraints on the operators, which are able to account for the magnitudes of some of the coefficients that are often set as arbitrary parameters in generic Abelian models.Comment: 30 pages, 6 figure

    Dissociative photoionization of the NO molecule studied by photoelectron-photon coincidence technique

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    Low-energy photoelectron–vacuum ultraviolet (VUV) photon coincidences have been measured using synchrotron radiation excitation in the inner-valence region of the nitric oxide molecule. The capabilities of the coincidence set-up were demonstrated by detecting the 2s−1 → 2p−1 radiative transitions in coincidence with the 2s photoelectron emission in Ne. In NO, the observed coincidence events are attributed to dissociative photoionization with excitation, whereby photoelectron emission is followed by fragmentation of excited NO+ ions into O+ + N* or N+ + O* and VUV emission from an excited neutral fragment. The highest coincidence rate occurs with the opening of ionization channels which are due to correlation satellites of the 3σ photoionization. The decay time of VUV photon emission was also measured, implying that specific excited states of N atoms contribute significantly to observed VUV emission

    Non-resonant leptogenesis in seesaw models with an almost conserved B-L

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    We review the motivations and some results on leptogenesis in seesaw models with an almost conserved lepton number. The paper is based on a talk given at the 5th International Symposium on Symmetries in Subatomic Physics, SSP2012.Comment: 8 pages, 1 figure. Published in the proceedings of the 5th International Symposium on Symmetries in Subatomic Physics, SSP201

    FRW Cosmology with Non-positively Defined Higgs Potentials

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    We discuss the classical aspects of dynamics of scalar models with non-positive Higgs potentials in the FRW cosmology. These models appear as effective local models in non-local models related with string field theories. After a suitable field redefinition these models have the form of local Higgs models with a negative extra cosmological term and the total Higgs potential is non-positively defined and has rather small coupling constant. The non-positivity of the potential leads to the fact that on some stage of evolution the expansion mode gives place to the mode of contraction, due to that the stage of reheating is absent. In these models the hard regime of inflation gives place to inflation near the hill top and the area of the slow roll inflation is very small. Meanwhile one can obtain enough e-foldings before the contraction to make the model under consideration admissible to describe inflation.Comment: 40 pages, 20 figures, typos correcte

    Dataset of characteristic remanent magnetization and magnetic properties of early Pliocene sediments from IODP Site U1467 (Maldives platform)

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    This data article describes data of magnetic stratigraphy and anisotropy of isothermal remanent magnetization (AIRM) from "Magnetic properties of early Pliocene sediments from IODP Site U1467 (Maldives platform) reveal changes in the monsoon system" [1]. Acquisition of isothermal magnetization on pilot samples and anisotropy of isothermal remanent magnetization are reported as raw data; magnetostratigraphic data are reported as characteristic magnetization (ChRM).info:eu-repo/semantics/publishedVersio

    Highly indistinguishable single photons from droplet-etched GaAs quantum dots integrated in single-mode waveguides and beamsplitters

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    The integration of on-demand quantum emitters into photonic integrated circuits (PICs) has drawn much of attention in recent years, as it promises a scalable implementation of quantum information schemes. A central property for several applications is the indistinguishability of the emitted photons. In this regard, GaAs quantum dots (QDs) obtained by droplet etching epitaxy show excellent performances with visibilities close to one for both individual and remote emitters. Therefore, the realization of these QDs into PICs is highly appealing. Here, we show the first implementation in this direction, realizing the key passive elements needed in PICs, i.e. single-mode waveguides (WGs) with integrated GaAs-QDs, which can be coherently controlled, as well as beamsplitters. We study both the statistical distribution of wavelength, linewidth and decay times of the excitonic line of multiple QDs, as well as the quantum optical properties of individual emitters under resonant excitation. Here, we achieve single-photon purities as high as 1g(2)(0)=0.929±0.0091-\text{g}^{(2)}(0)=0.929\pm0.009 as well as two-photon interference visibilities of up to VTPI=0.939±0.004_{\text{TPI}}=0.939\pm0.004 for two consecutively emitted photons

    Heart rate variability and target organ damage in hypertensive patients

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    Background: We evaluated the association between linear standard Heart Rate Variability (HRV) measures and vascular, renal and cardiac target organ damage (TOD). Methods: A retrospective analysis was performed including 200 patients registered in the Regione Campania network (aged 62.4 ± 12, male 64%). HRV analysis was performed by 24-h holter ECG. Renal damage was assessed by estimated glomerular filtration rate (eGFR), vascular damage by carotid intima-media thickness (IMT), and cardiac damage by left ventricular mass index. Results: Significantly lower values of the ratio of low to high frequency power (LF/HF) were found in the patients with moderate or severe eGFR (p-value < 0.001). Similarly, depressed values of indexes of the overall autonomic modulation on heart were found in patients with plaque compared to those with a normal IMT (p-value <0.05). These associations remained significant after adjustment for other factors known to contribute to the development of target organ damage, such as age. Moreover, depressed LF/HF was found also in patients with left ventricular hypertrophy but this association was not significant after adjustment for other factors. Conclusions: Depressed HRV appeared to be associated with vascular and renal TOD, suggesting the involvement of autonomic imbalance in the TOD. However, as the mechanisms by which abnormal autonomic balance may lead to TOD, and, particularly, to renal organ damage are not clearly known, further prospective studies with longitudinal design are needed to determine the association between HRV and the development of TOD

    Sterile neutrino portal to Dark Matter I: the U(1) B−L case

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    In this paper we explore the possibility that the sterile neutrino and Dark Matter sectors in the Universe have a common origin. We study the consequences of this assumption in the simple case of coupling the dark sector to the Standard Model via a global U(1)B−L, broken down spontaneously by a dark scalar. This dark scalar provides masses to the dark fermions and communicates with the Higgs via a Higgs portal coupling. We find an interesting interplay between Dark Matter annihilation to dark scalars — the CP-even that mixes with the Higgs and the CP-odd which becomes a Goldstone boson, the Majoron — and heavy neutrinos, as well as collider probes via the coupling to the Higgs. Moreover, Dark Matter annihilation into sterile neutrinos and its subsequent decay to gauge bosons and quarks, charged leptons or neutrinos lead to indirect detection signatures which are close to current bounds on the gamma ray flux from the galactic center and dwarf galaxies
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