311 research outputs found
Characteristics of proton velocity distribution functions in the near-lunar wake from Chandrayaan-1/SWIM observations
Due to the high absorption of solar wind plasma on the lunar dayside, a large
scale wake structure is formed downstream of the Moon. However, recent in-situ
observations have revealed the presence of protons in the near-lunar wake (100
km to 200 km from the surface). The solar wind, either directly or after
interaction with the lunar surface (including magnetic anomalies), is the
source of these protons in the near-wake region. Using the entire data from the
SWIM sensor of the SARA experiment onboard Chandrayaan-1, we analysed the
velocity distribution of the protons observed in the near-lunar wake. The
average velocity distribution functions, computed in the solar wind rest frame,
were further separated based on the angle between the upstream solar wind
velocity and the IMF. Several proton populations were identified from the
velocity distribution and their possible entry mechanism were inferred based on
the characteristics of the velocity distribution. These entry mechanisms
include (i) diffusion of solar wind protons into the wake along IMF, (ii) the
solar wind protons with finite gyro-radii that are aided by the wake boundary
electric field, (iii) solar wind protons with gyro-radii larger than lunar
radii from the tail of the solar wind velocity distribution, and (iv)
scattering of solar wind protons from the dayside lunar surface or from
magnetic anomalies. In order to gain more insight into the entry mechanisms
associated with different populations, backtracing is carried out for each of
these populations. For most of the populations, the source of the protons
obtained from backtracing is found to be in agreement with that inferred from
the velocity distribution. There are few populations that could not be
explained by the known mechanisms and remain unknown.Comment: 8 figures, paper accepted in Icarus (2016),
http://dx.doi.org/10.1016/j.icarus.2016.01.03
An intense, slow and cold beam of metastable Ne(3s) ^3P_2 atoms
We employ laser cooling to intensify and cool an atomic beam of metastable
Ne(3s) atoms. Using several collimators, a slower and a compressor we achieve a
^{20}Ne^* flux of 6 10^{10} atoms/s in an 0.7 mm diameter beam traveling at 100
m/s, and having longitudinal and transverse temperatures of 25mK and 300microK,
respectively. This constitutes the highest flux in a concentrated beam achieved
to date with metastable rare gas atoms. We characterize the action of the
various cooling stages in terms of their influence on the flux, diameter and
divergence of the atomic beam. The brightness and brilliance achieved are 2.1
10^{21} s^{-1} m^{-2} sr^{-1} and 5.0 10^{22} s^{-1} m^{-2} sr^{-1},
respectively, comparable to the highest values reported for alkali-metal beams.
Bright beams of the ^{21}Ne and ^{22}Ne isotopes have also been created.Comment: 18 pages, 9 figures, RevTe
Studying the Lunar-Solar Wind Interaction with the SARA Experiment aboard the Indian Lunar Mission Chandrayaan-1
The first Indian lunar mission Chandrayaan-1 was launched on 22 October 2008.
The Sub-keV Atom Reflecting Analyzer (SARA) instrument onboard Chandrayaan-1
consists of an energetic neutral atom (ENA) imaging mass analyzer called CENA
(Chandrayaan-1 Energetic Neutrals Analyzer), and an ion-mass analyzer called
SWIM (Solar wind Monitor). CENA performed the first ever experiment to study
the solar wind-planetary surface interaction via detection of sputtered neutral
atoms and neutralized backscattered solar wind protons in the energy range
~0.01-3.0 keV. SWIM measures solar wind ions, magnetosheath and magnetotail
ions, as well as ions scattered from lunar surface in the ~0.01-15 keV energy
range. The neutral atom sensor uses conversion of the incoming neutrals to
positive ions, which are then analyzed via surface interaction technique. The
ion mass analyzer is based on similar principle. This paper presents the SARA
instrument and the first results obtained by the SWIM and CENA sensors. SARA
observations suggest that about 20% of the incident solar wind protons are
backscattered as neutral hydrogen and ~1% as protons from the lunar surface.
These findings have important implications for other airless bodies in the
solar system.Comment: 4 pages, 6 figure
Heteronuclear ionizing collisions between laser-cooled metastable helium atoms
We have investigated cold ionizing heteronuclear collisions in dilute
mixtures of metastable (2 3S1) 3He and 4He atoms, extending our previous work
on the analogous homonuclear collisions [R. J. W. Stas et al., PRA 73, 032713
(2006)]. A simple theoretical model of such collisions enables us to calculate
the heteronuclear ionization rate coefficient, for our quasi-unpolarized gas,
in the absence of resonant light (T = 1.2 mK): K34(th) = 2.4*10^-10 cm^3/s.
This calculation is supported by a measurement of K34 using magneto-optically
trapped mixtures containing about 1*10^8 atoms of each species, K34(exp) =
2.5(8)*10^-10 cm^3/s. Theory and experiment show good agreement.Comment: 8 pages, 6 figure
Певні недоліки функціонування Державного бюро розслідувань
Стась М. Е. Певні недоліки функціонування Державного бюро розслідувань / М. Е. Стась // Державне бюро розслідувань: на шляху розбудови : матер. Міжнар. наук.-практ. конф. (м. Одеса, 16 червня 2018 р.) / редкол.: Г. О. Ульянова (голова ред.), В. М. Дрьомін, Є. Л. Стрельцов [та ін.] ; НУ "ОЮА". - Одеса : Юридична література, 2018. - С. 211-213
Composition and formation of the sleeve enveloping a central venous catheter
AbstractPurpose:After catheterization, 42% to 100% of central venous catheters are surrounded by a “fibrin sleeve.” This sleeve has been considered the cause of catheter-related infections, withdrawal occlusion, and pulmonary embolism. The reactions between the vein wall and the catheter were studied. Methods: A silicone catheter was placed in the anterior caval vein of 123 rats. After in situ fixation at scheduled intervals, the pathologic changes were studied on semi-serial histologic sections by means of light microscopy, transmission electron microscopy, and scanning electron microscopy (SEM). In 36 rats, the catheter was withdrawn immediately; in 72 rats, it was left in situ up to 6 months; and in 15 rats, the study was performed up to 10 months after withdrawal of a catheter that had remained in situ for 6 months. Results: In the group in which the catheter was withdrawn immediately, mural thrombi disappeared by day 7. In the group in which the catheter remained in situ, thrombi remained around the proximal portion of the catheter. This pericatheter thrombosis (PCT) was invaded by migrating and proliferating smooth muscle cells (SMCs), originating from an injured vein wall, and transformed from day 7 into a tissue composed predominantly of SMCs and collagen and covered by endothelial cells. Later, the number of cells decreased, and the relative amount of collagen increased. Up to 10 months after withdrawal of the catheter, the collapsed sleeve was still present within the vein. Conclusion: The sleeve around a central venous catheter is not a fibrin sleeve, but a stable cellular-collagen tissue covered by endothelium. It is mainly formed by smooth muscle cells migrating from the injured vein wall into the early pericatheter thrombus. (J Vasc Surg 1998;28:260-271.
An approach to fulfill art 8 of directive 2009/128: procedure of risk assessment for pesticide application equipment
The EU Directive 2009/128/EC on the sustainable use of pesticides requires that Member States (MS) shall ensure that all Pesticide Application Equipment (PAE) in professional use shall be subject to inspection at regular intervals. Article 8.3 of the Directive allows the MS to derogate from the mandatory inspection at regular intervals or to apply different timetables and inspection intervals for certain types of PAE based on a Risk Assessment (RA) for human health, food safety and environment and an assessment of the scale of use. In order to fulfill Article 8.3, a risk assessment protocol was developed in Belgium within the framework of the SIRA-APESTICON project. Risk is now evaluated for the human health and the environment on all Belgian equipment. It will offer guidelines about the necessity to carry out an inspection of every PAE in use. The protocol is based on technical parameters subject to inspections, their occurrences and severities, but also on national scale of use of the PAE types. Results are expressed at different scale levels: the defect, the machine and the country.The EU Directive 2009/128/EC on the sustainable use of pesticides requires that Member States (MS) shall ensure that all Pesticide Application Equipment (PAE) in professional use shall be subject to inspection at regular intervals. Article 8.3 of the Directive allows the MS to derogate from the mandatory inspection at regular intervals or to apply different timetables and inspection intervals for certain types of PAE based on a Risk Assessment (RA) for human health, food safety and environment and an assessment of the scale of use. In order to fulfill Article 8.3, a risk assessment protocol was developed in Belgium within the framework of the SIRA-APESTICON project. Risk is now evaluated for the human health and the environment on all Belgian equipment. It will offer guidelines about the necessity to carry out an inspection of every PAE in use. The protocol is based on technical parameters subject to inspections, their occurrences and severities, but also on national scale of use of the PAE types. Results are expressed at different scale levels: the defect, the machine and the country
Magneto-optical trapping of bosonic and fermionic neon isotopes and their mixtures: isotope shift of the ^3P_2 to ^3D_3 transition and hyperfine constants of the ^3D_3 state of Ne-21
We have magneto-optically trapped all three stable neon isotopes, including
the rare Ne-21, and all two-isotope combinations. The atoms are prepared in the
metastable ^3P_2 state and manipulated via laser interaction on the ^3P_2 to
^3D_3} transition at 640.2nm. These cold (T = 1mK) and environmentally
decoupled atom samples present ideal objects for precision measurements and the
investigation of interactions between cold and ultracold metastable atoms. In
this work, we present accurate measurements of the isotope shift of the ^3P_2
to ^3D_3 transition and the hyperfine interaction constants of the ^3D_3 state
of Ne-21. The determined isotope shifts are (1625.9\pm0.15)MHz for Ne-20 to
Ne-22, (855.7\pm1.0)MHz for Ne-20 to Ne-21, and (770.3\pm1.0)MHz for Ne-21 to
Ne-22. The obtained magnetic dipole and electric quadrupole hyperfine
interaction constants are A(^3D_3)= (-142.4\pm0.2)MHz and
B(^3D_3)=(-107.7\pm1.1)MHz, respectively. All measurements give a reduction of
uncertainty by about one order of magnitude over previous measurements
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