38 research outputs found
ОСОБЕННОСТИ ПОСТРОЕНИЯ ВИДЕОСПЕКТРОМЕТРОВ ДИСТАНЦИОННОГО ЗОНДИРОВАНИЯ ЗЕМЛИ ИЗ КОСМОСА
In article factors influencing quality of the Earth image received with imaging spectrometers are presented: height of an orbit of a spacecraft, atmosphere, characteristics of the optical scheme, type of dispersive element and a photodetector. Results of study of influence of the optical system parameters of a video spectrometer of factors are presented taking into account requirements and restrictions brought by various links of an optoelectronic path of the device.В статье показаны факторы, влияющие на качество изображения Земли, получаемого с помощью видеоспектрометров: высота орбиты космического аппарата, атмосфера, характеристики оптической схемы, вид диспергирующего элемента, вид фотоприемника. Представлены результаты проработки вопроса о влиянии на параметры оптической системы видеоспектрометра указанных факторов, исходя из требований и ограничений вносимых различными звеньями оптико-электронного тракта
Near and Mid-IR Photometry of the Pleiades, and a New List of Substellar Candidate Members
We make use of new near and mid-IR photometry of the Pleiades cluster in
order to help identify proposed cluster members. We also use the new photometry
with previously published photometry to define the single-star main sequence
locus at the age of the Pleiades in a variety of color-magnitude planes.
The new near and mid-IR photometry extend effectively two magnitudes deeper
than the 2MASS All-Sky Point Source catalog, and hence allow us to select a new
set of candidate very low mass and sub-stellar mass members of the Pleiades in
the central square degree of the cluster. We identify 42 new candidate members
fainter than Ks =14 (corresponding to 0.1 Mo). These candidate members should
eventually allow a better estimate of the cluster mass function to be made down
to of order 0.04 solar masses.
We also use new IRAC data, in particular the images obtained at 8 um, in
order to comment briefly on interstellar dust in and near the Pleiades. We
confirm, as expected, that -- with one exception -- a sample of low mass stars
recently identified as having 24 um excesses due to debris disks do not have
significant excesses at IRAC wavelengths. However, evidence is also presented
that several of the Pleiades high mass stars are found to be impacting with
local condensations of the molecular cloud that is passing through the Pleiades
at the current epoch.Comment: Accepted to ApJS; data tables and embedded-figure version available
at http://spider.ipac.caltech.edu/staff/stauffer/pleiades07
Correlated errors in Hipparcos parallaxes towards the Pleiades and the Hyades
We show that the errors in the Hipparcos parallaxes towards the Pleiades and
the Hyades open clusters are spatially correlated over angular scales of 2 to 3
deg, with an amplitude of up to 2 mas. This correlation is stronger than
expected based on the analysis of the Hipparcos catalog. We predict the
parallaxes of individual cluster members, pi_pm, from their Hipparcos proper
motions, assuming that all cluster members have the same space velocity. We
compare pi_pm with their Hipparcos parallaxes, pi_Hip, and find that there are
significant spatial correlations in pi_Hip. We derive a distance modulus to the
Pleiades of 5.58 +- 0.18 mag using the radial-velocity gradient method. This
value, agrees very well with the distance modulus of 5.60 +- 0.04 mag
determined using the main-sequence fitting technique, compared with the value
of 5.33 +- 0.06 inferred from the average of the Hipparcos parallaxes of the
Pleiades members. We show that the difference between the main-sequence fitting
distance and the Hipparcos parallax distance can arise from spatially
correlated errors in the Hipparcos parallaxes of individual Pleiades members.
Although the Hipparcos parallax errors towards the Hyades are spatially
correlated in a manner similar to those of the Pleiades, the center of the
Hyades is located on a node of this spatial structure. Therefore, the parallax
errors cancel out when the average distance is estimated, leading to a mean
Hyades distance modulus that agrees with the pre-Hipparcos value. We speculate
that these spatial correlations are also responsible for the discrepant
distances that are inferred using the mean Hipparcos parallaxes to some open
clusters. Finally, we note that our conclusions are based on a purely geometric
method and do not rely on any models of stellar isochrones.Comment: 33 pages including 10 Figures, revised version accepted for
publication in Ap
Обратимая легочная гипертензия у пациентки после трансплантации почки с длительно функционирующей артериовенозной фистулой
Case report of reversible high pulmonary hypertension (PH) in patient with successful kidney transplantation (KT) is presented. The distinction of the case was the functioning arteriovenous fistula (AVF) with excessive blood flow during 15 years in the absence of indications for hemodialysis. Consequently, PH was complicated by serious congestive heart failure (CHF) with high cardiac output. Surgical closure of AVF resulted in complete regression of clinical, instrumental and laboratory signs and symptoms of PH and CHF within 2 weeks. The pathogenic role of excessive AVF blood flow in PH and CHF formation is a point of discussion. Surgical closure of AVF with excessive blood flow is recommended in cases of presence of symptomatic PH and CHF in patients after successful KT.Представлено описание клинического случая обратимой высокой легочной гипертензии (ЛГ) у пациентки с успешной трансплантацией почки (ТП), особенностью которого было функционирование артериовенозной фистулы (АВФ) с избыточным кровотоком в течение 15 лет при отсутствии показаний к проведению гемодиализа. ЛГ сопровождалась развитием тяжелой застойной сердечной недостаточности (ЗСН) с высоким сердечным выбросом. Лигирование АВФ привело к полному регрессу клинико-инструментальных и лабораторных признаков ЛГ и ЗСН в течение 2 недель. Обсуждается патогенетическая роль избыточного кровотока по АВФ в формировании ЛГ и ЗСН. Рекомендуется лигирование АВФ с избыточным кровотоком в случае формирования симптомной ЛГ у пациентов после успешной ТП
2020 Clinical guidelines for Atrial fibrillation and atrial flutter
Russian Society of Cardiology (RSC).With the participation of Russian Scientific Society of Clinical Electrophysiology, Arrhythmology and Cardiac Pacing, Russian Association of Cardiovascular Surgeons.Approved by the Scientific and Practical Council of the Russian Ministry of Health
FEATURES OF CONSTRUCTION REMOTE SENSING IMAGING SPECTROMETERS FROM SPACE
In article factors influencing quality of the Earth image received with imaging spectrometers are presented: height of an orbit of a spacecraft, atmosphere, characteristics of the optical scheme, type of dispersive element and a photodetector. Results of study of influence of the optical system parameters of a video spectrometer of factors are presented taking into account requirements and restrictions brought by various links of an optoelectronic path of the device