129 research outputs found
Stability of Triple Star Systems with Highly Inclined Orbits
It is well established that certain detached eclipsing binary stars exhibit
apsidal motions whose value is in disagreement with with calculated deviations
from Keplerian motion based on tidal effects and the general theory of
relativity. Although many theoretical senarios have been demonstrated to bring
calculations into line with observations, all have seemed unlikely for various
reasons. In particular, it has been established that the hypothesis of a third
star in an orbit almost perpendicular to the orbital plane of the close binary
system can explain the anomalous motion in at least some cases. The stability
of triple star systems with highly inclined orbits has been in doubt, however.
We have found conditions which allow the long term stability of such systems
so that the third body hypothesis now seems a likely resolution of the apsidal
motion problem. We apply our stability criteria to the cases of AS Cam and DI
Her and recommend observations at the new Keck interferometer which should be
able to directly observe the third bodies in these systems.Comment: edited to match published versio
CLINICAL CHARACTERISTICS OF MYCOPLASMA PNEUMONIA IN HOSPITALIZED PATIENTS
Aim. The research was designed for clinical and laboratory characteristics and treatment of respiratory mycoplasma pneumonia in adult patients hospitalized to the infectious diseases hospital of the city of Krasnodar.Materials and methods. The frequency of occurrence and the nature of the clinical symptoms confirmed by ELISA analysis of mycoplasma pneumonia in 35 patients, who were treated in the State Budgetary Establishment of Public Health Services “Specialized Clinical Infectious Hospital” of Krasnodar, were retrospectively analyzed.Results.Mycoplasma pneumonia in hospitalized patients of Krasnodar is more common in young men during the cold season and occurs in moderate form. When ranking the clinical symptoms, it has been established that the priority signs of the disease are acute onset, febrile temperature, symptoms of lesions of the upper respiratory tract, increased CRP, dry coughing and relative monocytosis in the general blood test that can be considered the suggestive symptoms of the disease. Antimicrobial drugs from the macrolide, fluorinated quinolone and tetracycline groups, either as a monotherapy or in the combination, were prescribed for the patients with mycoplasma pneumonia.Conclusion. The frequency of occurrence and the absence of pathognomonic symptoms of mycoplasma pneumonia make it advisable to include an enzyme immunoassay for antibodies to “atypical” pathogens in the examination algorithm of patients with any pneumonia, which will provide more accurate diagnosis and correction of etiotropic therapy
Influence of VEGF deprivation upon vascular formation by endothelium in the presence of macrophages
Development of angiogenesis depends on the functional state of endothelial cells, as well as on the balanced secretion of cytokines, growth factors and chemokines by endothelial cells and cells of microenvironment. Macrophages represent an essential component of the microenvironment and take part in the formation of blood vessels both due to the production of cytokines and due to contact interactions with endothelial cells. VEGF is among the most important cytokines that control angiogenesis at all its stages. Currently, the role of VEGF in the intercellular interactions of endothelial cells and macrophages is not well described. The aim of our study was to investigate the effect of VEGF deprivation using monoclonal antibodies on angiogenesis under conditions of co-cultivation of endothelium and macrophages. Materials and methods: monoclonal antibodies to VEGF-A were used for VEGF deprivation in monoculture of endothelial cells and in co-culture of endothelial cells with macrophages. The IL-1β, IL-6 and TNFα cytokines were used as inducers. When VEGF-A was removed from the medium, endothelial cells show plasticity and form longer vessels, they modify the expression of VEGF receptors. Macrophages regulate endothelial cell activity through the secretion of cytokines, including VEGF, and through contact interactions with endothelial cells. THP-1 cells increase the sensitivity of endothelial cells to VEGF by stimulating the VEGFR1 and VEGFR3 expression, this effect is VEGF-A-independent. The IL-1β, IL-6, TNFa cytokines independently stimulate non-branching angiogenesis, increasing the length of the vessels. At the same time, IL-ip increases the VEGFR1 expression on the surface of endothelial cells. In contrast, IL-6 and TNFα decrease it, thereby regulating the sensitivity of endothelial cells to VEGF. The effects of these cytokines are not dependent on VEGF-A. The IL-1β, IL-6, TNFα cytokines promote acquisition of anti-angiogenic properties by THP-1 cells that is independent on VEGF-A, as well as on expression of its receptors by endothelial cells. Thus, VEGF is an important, but not the sole factor controlling angiogenesis. Under conditions of VEGF-A deficiency, either endothelial cells or microenvironment cells are able to compensate for its functional load due to the production of other growth factors
Risk factors for anemia in newborns
The objective was to assess clinical and anamnestic indicators and characteristics of blood erythrocytes in newborns according to the severity of anemia. Materials and methods: we examined the 65 case records of newborns with anemia who received medical treatment in pathology department of Rostov Research Institute of Obstetrics and Pediatrics from November, 2015 to March, 2016. All newborns were divided into 3 groups depending on the severity of anemia: I group included 40 newborns with mild case of anemia, II group – 8 infants with medium-heavy anemia, III group – 17 newborns with heavy extent of disease. Results. The most common risk factors of severe anemia on the distaff side are obesity (35.3%), anemia (100%), threatened miscarriage (65,%), cytomegalovirus infection (41%), gestational diabetes (or 41.2%). Conclusion: The risk factors of anemia in newborns are unfavorable for the antenatal period complicated by anemia, threatened miscarriage, gestational diabetes mellitus, cytomegalovirus infection, presence of respiratory distress syndrome, cerebral ischemia II degree in combination with hemolytic disease of the newborn
Transitional events in the spectrophotometric regime between stripped envelope and superluminous supernovae
KM, MRM, and SJP are supported by H2020 ERC grant no. 758638.
LG acknowledges financial support from the European Union’s
Horizon 2020 research and innovation programme under the Marie
Skłodowska-Curie grant agreement no. 839090, and from the
Spanish Ministry of Science, Innovation and Universities (MICIU)
under the 2019 Ramon y Cajal programme RYC2019-027683. TMB ´
was funded by the CONICYT PFCHA / DOCTORADOBECAS
CHILE/2017-72180113. MG is supported by the EU Horizon 2020
research and innovation programme under grant agreement no.
101004719. SGG acknowledges support by FCT under Project
CRISP PTDC/FIS-AST-31546/2017. MN is supported by a Royal
Astronomical Society Research Fellowship and H2020 ERC grant
no. 948381. T-WC acknowledges the EU Funding under Marie
Skłodowska-Curie grant H2020-MSCA-IF-2018-842471. The LT
is operated on the island of La Palma by Liverpool John Moores
University in the Spanish Observatorio del Roque de los Muchachos
of the Instituto de Astrofisica de Canarias with financial support
from the UK Science and Technology Facilities Council. Based
on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere, Chile, as part of
ePESSTO+ (the advanced Public ESO Spectroscopic Survey for
Transient Objects Survey). ePESSTO+ observations were obtained
under ESO programme ID 1103.D-0328 (PI: Inserra). The WHT is
operated on the island of La Palma by the Isaac Newton Group of
Telescopes in the Spanish Observatorio del Roque de los Muchachos
of the Instituto de Astrof´ısica de Canarias. SJP thanks GPL for many
insightful discussions at the bar over the last few years.The division between stripped-envelope supernovae (SE-SNe) and superluminous supernovae (SLSNe) is not well-defined in either photometric or spectroscopic space. While a sharp luminosity threshold has been suggested, there remains an increasing number of transitional objects that reach this threshold without the spectroscopic signatures common to SLSNe. In this work, we present data and analysis on four SNe transitional between SE-SNe and SLSNe; the He-poor SNe 2019dwa and 2019cri, and the He-rich SNe 2019hge and 2019unb. Each object displays long-lived and variable photometric evolution with luminosities around the SLSN threshold of Mr < -19.8 mag. Spectroscopically however, these objects are similar to SE-SNe, with line velocities lower than either SE-SNe and SLSNe, and thus represent an interesting case of rare transitional events.H2020 ERC grant no. 758638European Union’s
Horizon 2020 research and innovation programme under the Marie
Skłodowska-Curie grant agreement no. 839090Spanish Ministry of Science, Innovation and Universities (MICIU)
under the 2019 Ramon y Cajal programme RYC2019-027683CONICYT PFCHA / DOCTORADOBECAS
CHILE/2017-72180113EU Horizon 2020
research and innovation programme under grant agreement no.
101004719FCT under Project
CRISP PTDC/FIS-AST-31546/2017Royal
Astronomical Society Research FellowshipH2020 ERC grant
no. 948381UK Science and Technology Facilities CouncilESO programme ID 1103.D-0328 (PI: Inserra
The Morphology of Asteroidal Dust Around White Dwarf Stars: Optical and Near-infrared Pulsations in G29-38
More than 36 years have passed since the discovery of the infrared excess
from circumstellar dust orbiting the white dwarf G29-38, which at 17.5 pc it is
the nearest and brightest of its class. The precise morphology of the orbiting
dust remains only marginally constrained by existing data, subject to
model-dependent inferences, and thus fundamental questions of its dynamical
origin and evolution persist. This study presents a means to constrain the
geometric distribution of the emitting dust using stellar pulsations measured
at optical wavelengths as a variable illumination source of the dust, which
re-radiates primarily in the infrared. By combining optical photometry from the
Whole Earth Telescope with 0.7-2.5 micron spectroscopy obtained with SpeX at
NASA's Infrared Telescope Facility, we detect luminosity variations at all
observed wavelengths, with variations at most wavelengths corresponding to the
behavior of the pulsating stellar photosphere, but towards the longest
wavelengths the light curves probe the corresponding time-variability of the
circumstellar dust. In addition to developing methodology, we find pulsation
amplitudes decrease with increasing wavelength for principal pulsation modes,
yet increase beyond approximately 2 microns for nonlinear combination
frequencies. We interpret these results as combination modes deriving from
principal modes of identical l values and discuss the implications for the
morphology of the warm dust. We also draw attention to some discrepancies
between our findings and theoretical expectations for the results of the
non-linearity imposed by the surface convection zone on mode--mode interactions
and on the behavior of the first harmonic of the highest-amplitude pulsation
mode.Comment: 12 pages, 6 figures, to be published in The Astrophysical Journa
Unprecedented early flux excess in the hybrid 02es-like type Ia supernova 2022ywc indicates interaction with circumstellar material
We present optical photometric and spectroscopic observations of the
02es-like type Ia supernova (SN) 2022ywc. The transient occurred in the
outskirts of an elliptical host galaxy and showed a striking double-peaked
light curve with an early excess feature detected in the ATLAS orange and cyan
bands. The early excess is remarkably luminous with an absolute magnitude , comparable in luminosity to the subsequent radioactively-driven second
peak. The spectra resemble the hybrid 02es-like SN 2016jhr, that is considered
to be a helium shell detonation candidate. We investigate different physical
mechanisms that could power such a prominent early excess and rule out massive
helium shell detonation, surface Ni distribution and ejecta-companion
interaction. We conclude that SN ejecta interacting with circumstellar material
(CSM) is the most viable scenario. Semi-analytical modelling with MOSFiT
indicates that SN ejecta interacting with M of CSM at a
distance of cm can explain the extraordinary light curve. A
double-degenerate scenario may explain the origin of the CSM, either by
tidally-stripped material from the secondary white dwarf, or disk-originated
matter launched along polar axes following the disruption and accretion of the
secondary white dwarf. A non-spherical CSM configuration could suggest that a
small fraction of 02es-like events viewed along a favourable line of sight may
be expected to display a very conspicuous early excess like SN 2022ywc.Comment: Accepted to ApJL after minor revisio
Transitional events in the spectrophotometric regime between stripped envelope and superluminous supernovae
The division between stripped-envelope supernovae (SE-SNe) and superluminous supernovae (SLSNe) is not well-defined in either photometric or spectroscopic space. While a sharp luminosity threshold has been suggested, there remains an increasing number of transitional objects that reach this threshold without the spectroscopic signatures common to SLSNe. In this work, we present data and analysis on four SNe transitional between SE-SNe and SLSNe; the He-poor SNe 2019dwa and 2019cri, and the He-rich SNe 2019hge and 2019unb. Each object displays long-lived and variable photometric evolution with luminosities around the SLSN threshold of Mr < -19.8 mag. Spectroscopically however, these objects are similar to SE-SNe, with line velocities lower than either SE-SNe and SLSNe, and thus represent an interesting case of rare transitional events.KM, MRM, and SJP are supported by H2020 ERC grant no. 758638. LG acknowledges financial support from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement no. 839090, and from the Spanish Ministry of Science, Innovation and Universities (MICIU) under the 2019 Ramón y Cajal programme RYC2019-027683. TMB was funded by the CONICYT PFCHA / DOCTORADOBECAS CHILE/2017-72180113. MG is supported by the EU Horizon 2020 research and innovation programme under grant agreement no. 101004719. SGG acknowledges support by FCT under Project CRISP PTDC/FIS-AST-31546/2017. MN is supported by a Royal Astronomical Society Research Fellowship and H2020 ERC grant no. 948381. T-WC acknowledges the EU Funding under Marie Skłodowska-Curie grant H2020-MSCA-IF-2018-842471. The LT is operated on the island of La Palma by Liverpool John Moores University in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias with financial support from the UK Science and Technology Facilities Council
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