731 research outputs found
Periodic Bursts of Coherent Radio Emission from an Ultracool Dwarf
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
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?
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
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
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
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
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
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
Synchronization of the Distributed Readout Frontend Electronics of the Baby MIND Detector
Baby MIND is a new downstream muon range detector for the WGASCI experiment. This article discusses the distributed readout system and its timing requirements. The paper presents the design of the synchronization subsystem and the results of its test
Синтетический аналог лей-энкефалина при COVID-19 (проспективное клиническое исследование)
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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