724 research outputs found

    Periodic Bursts of Coherent Radio Emission from an Ultracool Dwarf

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    We report the detection of periodic (p = 1.96 hours) bursts of extremely bright, 100% circularly polarized, coherent radio emission from the M9 dwarf TVLM 513-46546. Simultaneous photometric monitoring observations have established this periodicity to be the rotation period of the dwarf. These bursts, which were not present in previous observations of this target, confirm that ultracool dwarfs can generate persistent levels of broadband, coherent radio emission, associated with the presence of kG magnetic fields in a large-scale, stable configuration. Compact sources located at the magnetic polar regions produce highly beamed emission generated by the electron cyclotron maser instability, the same mechanism known to generate planetary coherent radio emission in our solar system. The narrow beams of radiation pass our line of sight as the dwarf rotates, producing the associated periodic bursts. The resulting radio light curves are analogous to the periodic light curves associated with pulsar radio emission highlighting TVLM 513-46546 as the prototype of a new class of transient radio source.Comment: 12 pages, 3 figures, accepted for publication in ApJ Letter

    Rotational Modulation of M/L Dwarfs due to Magnetic Spots

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    We find periodic I-band variability in two ultracool dwarfs, TVLM 513-46546 and 2MASS J00361617+1821104, on either side of the M/L dwarf boundary. Both of these targets are short-period radio transients, with the detected I-band periods matching those found at radio wavelengths (P = 1.96 hr for TVLM 513-46546 and P = 3 hr for 2MASS J00361617+1821104). We attribute the detected I-band periodicities to the periods of rotation of the dwarfs, supported by radius estimates and measured v sin i values for the objects. Based on the detected period of rotation of TVLM 513-46546 (M9) in the I band, along with confirmation of strong magnetic fields from recent radio observations, we argue for magnetically induced spots as the cause of this periodic variability. The I-band rotational modulation of the L3.5 dwarf 2MASS J00361617+1821104 appeared to vary in amplitude with time. We conclude that the most likely cause of the I-band variability for this object is magnetic spots, possibly coupled with time-evolving features such as dust clouds

    Is the Shroud of Turin in Relation to the Old Jerusalem Historical Earthquake?

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    Phillips and Hedges suggested, in the scientific magazine Nature (1989), that neutron radiation could be liable of a wrong radiocarbon dating, while proton radiation could be responsible of the Shroud body image formation. On the other hand, no plausible physical reason has been proposed so far to explain the radiation source origin, and its effects on the linen fibres. However, some recent studies, carried out by the first author and his Team at the Laboratory of Fracture Mechanics of the Politecnico di Torino, found that it is possible to generate neutron emissions from very brittle rock specimens in compression through piezonuclear fission reactions. Analogously, neutron flux increments, in correspondence to seismic activity, should be a result of the same reactions. A group of Russian scientists measured a neutron flux exceeding the background level by three orders of magnitude in correspondence to rather appreciable earthquakes (4th degree in Richter Scale). The authors consider the possibility that neutron emissions by earthquakes could have induced the image formation on Shroud linen fibres, trough thermal neutron capture by Nitrogen nuclei, and provided a wrong radiocarbon dating due to an increment in C(14,6)content. Let us consider that, although the calculated integral flux of 10^13 neutrons per square centimetre is 10 times greater than the cancer therapy dose, nevertheless it is100 times smaller than the lethal dose.Comment: 13 pages, 1 figur

    Confirmation of the Electron Cyclotron Maser Instability as the Dominant Source of Radio Emission from Very Low Mass Stars and Brown Dwarfs

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    We report on radio observations of the M8.5 dwarf LSR J1835+3259 and the L3.5 dwarf 2MASS J00361617+1821104, which provide the strongest evidence to date that the electron cyclotron maser instability is the dominant mechanism producing radio emission in the magnetospheres of ultracool dwarfs. As has previously been reported for the M9 dwarf TVLM 513-46546, periodic pulses of 100% circularly polarized, coherent radio emission are detected from both dwarfs with periods of 2.84 +/- 0.01 and 3.08 +/- 0.05 hours respectively for LSR J1835+3259 and 2MASS J00361617+1821104. Importantly, periodic unpolarized radio emission is also detected from 2MASS J00361617+1821104, and brightness temperature limitations rule out gyrosynchrotron radiation as a source of this radio emission. The unpolarized emission from this and other ultracool dwarfs is also attributed to electron cyclotron maser emission, which has become depolarized on traversing the ultracool dwarf magnetosphere, possibly due to propagations effects such as scattering. Based on available v sin i data in the literature and rotation periods derived from the periodic radio data for the three confirmed sources of electron cyclotron maser emission, TVLM 513-46546, LSR J1835+3259 and 2MASS J00361617+1821104, we determine that the rotation axes of all three dwarfs are close to perpendicular to our line of sight. This suggests a possible geometrical selection effect due to the inherent directivity of electron cyclotron maser emission, that may account for the previously reported relationship between radio activity and v sin i observed for ultracool dwarfs. We also determine the radius of the dwarf LSR J1835+3259 to be > 0.117 +/- 0.012 R_Sol. (abridged)Comment: 11 pages, 2 tables, 4 figures, accepted for publication in Ap

    Heat-Shock Protein 90 Controls the Expression of Cell-Cycle Genes by Stabilizing Metazoan-Specific Host-Cell Factor HCFC1

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    Molecular chaperones such as heat-shock proteins (HSPs) help in protein folding. Their function in the cytosol has been well studied. Notably, chaperones are also present in the nucleus, a compartment where proteins enter after completing de novo folding in the cytosol, and this raises an important question about chaperone function in the nucleus. We performed a systematic analysis of the nuclear pool of heat-shock protein 90. Three orthogonal and independent analyses led us to the core functional interactome of HSP90. Computational and biochemical analyses identify host cell factor C1 (HCFC1) as a transcriptional regulator that depends on HSP90 for its stability. HSP90 was required to maintain the expression of HCFC1-targeted cell-cycle genes. The regulatory nexus between HSP90 and the HCFC1 module identified in this study sheds light on the relevance of chaperones in the transcription of cell-cycle genes. Our study also suggests a therapeutic avenue of combining chaperone and transcription inhibitors for cancer treatment

    Baby MIND: A magnetised spectrometer for the WAGASCI experiment

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    The WAGASCI experiment being built at the J-PARC neutrino beam line will measure the difference in cross sections from neutrinos interacting with a water and scintillator targets, in order to constrain neutrino cross sections, essential for the T2K neutrino oscillation measurements. A prototype Magnetised Iron Neutrino Detector (MIND), called Baby MIND, is being constructed at CERN to act as a magnetic spectrometer behind the main WAGASCI target to be able to measure the charge and momentum of the outgoing muon from neutrino charged current interactions.Comment: Poster presented at NuPhys2016 (London, 12-14 December 2016). Title + 4 pages, LaTeX, 6 figure

    Baby MIND Experiment Construction Status

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    Baby MIND is a magnetized iron neutrino detector, with novel design features, and is planned to serve as a downstream magnetized muon spectrometer for the WAGASCI experiment on the T2K neutrino beam line in Japan. One of the main goals of this experiment is to reduce systematic uncertainties relevant to CP-violation searches, by measuring the neutrino contamination in the anti-neutrino beam mode of T2K. Baby MIND is currently being constructed at CERN, and is planned to be operational in Japan in October 2017.Comment: Poster presented at NuPhys2016 (London, 12-14 December 2016). 4 pages, LaTeX, 7 figure

    Baby MIND: A magnetized segmented neutrino detector for the WAGASCI experiment

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    T2K (Tokai-to-Kamioka) is a long-baseline neutrino experiment in Japan designed to study various parameters of neutrino oscillations. A near detector complex (ND280) is located 280~m downstream of the production target and measures neutrino beam parameters before any oscillations occur. ND280's measurements are used to predict the number and spectra of neutrinos in the Super-Kamiokande detector at the distance of 295~km. The difference in the target material between the far (water) and near (scintillator, hydrocarbon) detectors leads to the main non-cancelling systematic uncertainty for the oscillation analysis. In order to reduce this uncertainty a new WAter-Grid-And-SCintillator detector (WAGASCI) has been developed. A magnetized iron neutrino detector (Baby MIND) will be used to measure momentum and charge identification of the outgoing muons from charged current interactions. The Baby MIND modules are composed of magnetized iron plates and long plastic scintillator bars read out at the both ends with wavelength shifting fibers and silicon photomultipliers. The front-end electronics board has been developed to perform the readout and digitization of the signals from the scintillator bars. Detector elements were tested with cosmic rays and in the PS beam at CERN. The obtained results are presented in this paper.Comment: In new version: modified both plots of Fig.1 and added one sentence in the introduction part explaining Baby MIND role in WAGASCI experiment, added information for the affiliation

    Синтетический аналог лей-энкефалина при COVID-19 (проспективное клиническое исследование)

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    One of the main problems facing intensivists when treating patients with COVID-19 is severe and critical acute respiratory distress syndrome (ARDS) with the underlying viral pneumonia. The current guidelines of the Russian Ministry of Health (Version 15 of 22.02.22) do not include drugs with a lung protective effect. This issue could be solved by administration of a synthetic analogue of leu-enkephalin.Aim. Study the efficacy of a synthetic analogue of leu-enkephalin in ARDS in patients with COVID-19.Materials and methods. The study included 35 patients divided into 2 groups. Group 1 (main) patients (n=15) in addition to standard therapy received a continuous infusion of synthetic analogue of leu-enkephalin at a rate of 5 µg/kg/hour for 5 days. Patients from group 2 (control, n=20) were treated according to the Temporary Guidelines of the Ministry of Health (V.15), but without the synthetic analogue of leu-enkephalin. The radiological data, frequency, severity and evolution of respiratory complications, changes in P/F (PaO2/FiO2) ratio, as well as changes in the scores of prognostic APACHE II, SOFA, and NEWS scales were evaluated.Results. In patients taking the studied drug, the percentage of lung damage did not change with the median (IQR) of 0 [–8; 0], while in the control group it increased by approximately 10% with the median (IQR) of +10,0 [+2; +20] (P=0.001). The proportion of patients in group 1 with positive disease evolution within 5–9 days after treatment initiation was significantly higher and reached 46.7 [24.8; 69.9]%, whereas in group 2 it was 15.0 [5.2; 36.0]% (P=0.04). Also, in group 1, starting from day 4, the median P/F ratio was significantly higher than in group 2 reaching 220 [185;245] versus 127 [111;158], respectively (P=0.014). The need for non-invasive lung ventilation in group 1 on day 7 averaged 7%, while in group 2 it was as high as 45.0%, which was significantly higher than in the main group (P=0.013).Conclusions. The use of synthetic analogue of leu-enkephalin according to the specified regimen had a significant impact on the main parameters of the viral pneumonia severity. The results serve as a rationale for the development of a novel effective treatment strategy to supplement the current standard COVID-19 management.В действующие рекомендации МЗ (№15 от 22.02.22) не включены препараты с пульмонопротекторным эффектом. Вместе с тем, одна из основных проблем, с которой сталкивается врач отделения интенсивной терапии при лечении пациентов с COVID-19 — развитие тяжелого и крайне тяжелого ОРДС на фоне вирусной пневмонии. Синтетический аналог лей-энкефалина потенциально эффективен в решении данной проблемы.Цель исследования: изучить эффективность синтетического аналога лей-энкефалина при ОРДС у пациентов с COVID-19.Материалы и методы. В проспективное исследование включили 35 пациентов, разделенных на 2 группы. Группа 1 (основная, n=15) — терапию согласно 15-м временным рекомендациям МЗ дополнили продленной инфузией синтетического аналога лей-энкефалина со скоростью 5 мкг/кг/час в течении 5 дней. Группа II (контрольная, n=20) — проводили только стандартное лечение. Оценивали данные лучевой диагностики, частоту, тяжесть и динамику респираторных осложнений, изменения показателей P/F, прогностических шкал APACHE II, SOFA и NEWS.Результаты. У пациентов, получавших исследуемый препарат, процент повреждения ткани легких не изменился: Median (IQR) 0 [–8; 0], а в контрольной группе — увеличился в среднем на 10%: Median (IQR) +10,0 [+2; +20] (p=0,001). Доля пациентов в I группе с положительной динамикой в интервале сроков с 5-го по 9-й день была значимо выше и составила 46,7% [24,8%; 69,9%], в группе II — 15,0% [5,2%; 36,0%] (p=0,04). Также в группе I, начиная с 4-х суток, медиана индекса P/F была значимо выше, чем в группе II — 220 [185; 245] против 127 [111; 158], соответственно (p=0,014). Необходимость проведения НИВЛ в группе I к 7 суткам составила в среднем 6,7%, а в группе II — 45,0%, что было значимо выше по отношению к основной группе (p=0,013).Заключение. Применение синтетического аналога лей-энкефалина оказало значимое влияние на основные показатели тяжести течения вирусной пневмонии при COVID-19, что может служить обоснованием разработки новой эффективной стратегии лечения
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