7,655 research outputs found
Incorporation of privacy elements in space station design
Privacy exists to the extent that individuals can control the degree of social contact that they have with one another. The opportunity to withdraw from other people serves a number of important psychological and social functions, and is in the interests of safety, high performance, and high quality of human life. Privacy requirements for Space Station crew members are reviewed, and architectual and other guidelines for helping astronauts achieve desired levels of privacy are suggested. In turn, four dimensions of privacy are discussed: the separation of activities by areas within the Space Station, controlling the extent to which astronauts have visual contact with one another, controlling the extent to which astronauts have auditory contact with one another, and odor control. Each section presents a statement of the problem, a review of general solutions, and specific recommendations. The report is concluded with a brief consideration of how selection, training, and other procedures can also help Space Station occupants achieve satisfactory levels of seclusion
Biokemijske promjene u serumu dvogrbih deva pokusno invadiranih protozoonom Trypanosoma evansi i liječenih melarsenoksid-cisteamin hidrokloridom.
This study was carried out to study the effect of melarsenoxyde cysteamine hydrochloride (Cymelarsan®) in modulating serum biochemical changes in dromedaries experimentally infected with Trypanosoma evansi. A total of twenty dromedaries were used in the study. They were randomly divided into Groups A - D of 5 each. Group A was infected but treated with Cymelarsan® at 0.25 mg/kg body weight. Group B was the infected control; Group C was the uninfected control while Group D was uninfected but treated with Cymelarsan®. Uniform parasitaemia (2.4 ± 0.19) was observed following a pre-patent period of 4 days (Group A and B). Parasitemia increased significantly (P<0.05) to 210.2 ± 1.81 (Groups A) and 200.2 ± 1.77 (Group B) at 20 days post-infection (D.P.I.). Following treatment in Group A, parasitemia was not seen at 32 D.P.I. In Group B it attained a peak count of 400.2 ± 2.50 at day 36 D.P.I. On the one hand, alanineaminotransferase, creatinine, total bilirubin concentrations increased significantly (P<0.05) in the infected dromedaries while on the other serum glucose, and total protein levels decreased significantly (P<0.05). These biochemical changes were however amended to their pre-infection values at 16 D.P.I. in Group A in contrast to Group B. These parameters in Group C and Group D remained fairly constant. In conclusion, the infection caused biochemical changes suggestive of liver and kidney dysfunctions, with muscular wasting, which were amended following treatments with Cymelarsan®.Istraživanje je provedeno da bi se odredio učinak melarsenoksid-cisteamin-hidroklorida (Cymelarsan®) na biokemijska obilježja u serumu dvogrbih deva pokusno invadiranih protozoonom Trypanosoma evansi. Pokus je proveden na 20 dvogrbih deva razvrstanih u skupine od A do D. Svaka skupina sadržavala je pet deva. Skupina A bila je invadirana i liječena pripravkom Cymelarsan® u dozi od 0,25 mg/kg tjelesne mase. Skupina B bila invadirana kontrola. Skupina C je bila neinvadirana kontrola dok je skupina D bila neinvadirana, ali je dobivala Cymelarsan®. Jednaka parazitemija (2,4 ± 0,19) bila je ustanovljena nakon prepatentnog razdoblja od svega 4 dana (skupina A i B). Jačina parazitemije značajno je porasla dvadesetog dana nakon invazije (P<0,05), do 210,2 ± 1,81 (skupina A) i 200,2 ± 1,77 (skupina B). U životinja skupine A nije zabilježena parazitemija 32. dana nakon invazije. U skupini B parazitemija je 36. dana poslije invazije iznosila 400,2 ± 2,50. U serumu invadiranih životinja značajno su porasle (P<0,05) vrijednosti alaninaminotransferaze, kreatinina i ukupnog bilirubina dok su se vrijednosti glukoze i ukupnih proteina značajno smanjile (P<0,05). Sve vrijednosti bile su različite u odnosu na 16. dan poslije invazije u životinja skupine A što nije bio slučaj u životinja skupine B. Vrijednosti u serumu životinja skupina C i D ostale su nepromijenjene. Zaključuje se da ustanovljene bikokemijske promjene upućuju na poremećenu funkciju jetre i bubrega te na iscrpljenost mišićja što se značajno popravilo nakon primjene Cymelarsana®
Human Performance in Extreme Environments
Even on a bad day, looking down from orbit is a powerful and enjoyable experience, enhanced by the knowledge that time in orbit represents only a tiny fraction of one's life. You look down at Earth and you feel a sense of peace and solidarity. You look at the stars, and because they are not obscured by atmosphere, they are far more abundant than you realized, and they shine very bright. Later on you will reflect on this as one of life's greatest moments. Today astronauts and a few wealthy space tourists have been able to experience staying on the International Space Station. As representatives of humankind in space, astronauts have to get out there and tell people what it's like, and to encourage successive generations of children to consider careers in space. Perhaps the more people who can experience this view, the nicer we will all be to one another. Astronauts must speak authoritatively, without arrogance or a lack of humility. Each astronaut is an emissary who can share his or her experiences and educate people who will not have the opportunity to fly in space. This chapter is a part of that communication process
Design of 12.5 kA current leads for the Large Hadron Collider using high temperature superconductor material
The Large Hadron Collider will be equipped with about 8000 superconducting magnets. Some 2600 current leads will feed the currents ranging from 25 to 12500 A. CERN aims to reduce the consumption of liquid helium, using high temperature superconductors in these leads. A development of leads for 12.5 kA is being conducted in collaboration with Oxford Instruments. The design options for these leads are described. A test rig and prototype lead have been made according to one of the options. Electrical contact tests are in progress on BSCCO-2212 and YBCO-123 samples. In the first run, the prototype carried 13000 A
GALEX, Optical and IR Light Curves of MQ Dra: UV Excesses at Low Accretion Rates
Ultraviolet light curves constructed from NUV and FUV detectors on GALEX
reveal large amplitude variations during the orbital period of the Low
Accretion Rate Polar MQ Dra (SDSSJ1553+55). This unexpected variation from a UV
source is similar to that seen and discussed in the Polar EF Eri during its low
state of accretion, even though the accretion rate in MQ Dra is an order of
magnitude lower than even the low state of EF Eri. The similarity in phasing of
the UV and optical light curves in MQ Dra imply a similar location for the
source of light. We explore the possibilities of hot spots and cyclotron
emission with simple models fit to the UV, optical and IR light curves of MQ
Dra. To match the GALEX light curves with a single temperature circular hot
spot requires different sizes of spots for the NUV and FUV, while a cyclotron
model that can produce the optical harmonics with a magnetic field near 60 MG
requires multipoles with fields > 200 MG to match the UV fluxes.Comment: accepted for ApJ; 15 pages, 7 tables, 8 fig
On Multiphase-Linear Ranking Functions
Multiphase ranking functions () were proposed as a means
to prove the termination of a loop in which the computation progresses through
a number of "phases", and the progress of each phase is described by a
different linear ranking function. Our work provides new insights regarding
such functions for loops described by a conjunction of linear constraints
(single-path loops). We provide a complete polynomial-time solution to the
problem of existence and of synthesis of of bounded depth
(number of phases), when variables range over rational or real numbers; a
complete solution for the (harder) case that variables are integer, with a
matching lower-bound proof, showing that the problem is coNP-complete; and a
new theorem which bounds the number of iterations for loops with
. Surprisingly, the bound is linear, even when the
variables involved change in non-linear way. We also consider a type of
lexicographic ranking functions, , more expressive than types
of lexicographic functions for which complete solutions have been given so far.
We prove that for the above type of loops, lexicographic functions can be
reduced to , and thus the questions of complexity of
detection and synthesis, and of resulting iteration bounds, are also answered
for this class.Comment: typos correcte
Deep Chandra observations of TeV binaries I: LSI +61 303
We report on a 95ks Chandra observation of the TeV emitting High Mass X-ray
Binary LSI +61 303, using the ACIS-S camera in Continuos Clocking mode to
search for a possible X-ray pulsar in this system. The observation was
performed while the compact object was passing from phase 0.94 to 0.98 in its
orbit around the Be companion star (hence close to the apastron passage). We
did not find any periodic or quasi-periodic signal (at this orbital phase) in a
frequency range of 0.005-175 Hz. We derived an average pulsed fraction 3 sigma
upper limit for the presence of a periodic signal of ~10% (although this limit
is strongly dependent on the frequency and the energy band), the deepest limit
ever reached for this object. Furthermore, the source appears highly variable
in flux and spectrum even in this very small orbital phase range, in particular
we detect two flares, lasting thousands of seconds, with a very hard X-ray
spectrum with respect to the average source spectral distribution. The X-ray
pulsed fraction limits we derived are lower than the pulsed fraction of any
isolated rotational-powered pulsar, in particular having a TeV counterpart. In
this scenario most of the X-ray emission of LSI +61 303 should necessarily come
from the interwind or inner-pulsar wind zone shock rather than from the
magnetosphere of the putative pulsar. Furthermore, we did not find evidence for
the previously suggested extended X-ray emission (abridged).Comment: 9 pages, 6 figures, MNRAS in pres
Biokemijske promjene u serumu dvogrbih deva pokusno invadiranih protozoonom Trypanosoma evansi i liječenih melarsenoksid-cisteamin hidrokloridom.
This study was carried out to study the effect of melarsenoxyde cysteamine hydrochloride (Cymelarsan®) in modulating serum biochemical changes in dromedaries experimentally infected with Trypanosoma evansi. A total of twenty dromedaries were used in the study. They were randomly divided into Groups A - D of 5 each. Group A was infected but treated with Cymelarsan® at 0.25 mg/kg body weight. Group B was the infected control; Group C was the uninfected control while Group D was uninfected but treated with Cymelarsan®. Uniform parasitaemia (2.4 ± 0.19) was observed following a pre-patent period of 4 days (Group A and B). Parasitemia increased significantly (P<0.05) to 210.2 ± 1.81 (Groups A) and 200.2 ± 1.77 (Group B) at 20 days post-infection (D.P.I.). Following treatment in Group A, parasitemia was not seen at 32 D.P.I. In Group B it attained a peak count of 400.2 ± 2.50 at day 36 D.P.I. On the one hand, alanineaminotransferase, creatinine, total bilirubin concentrations increased significantly (P<0.05) in the infected dromedaries while on the other serum glucose, and total protein levels decreased significantly (P<0.05). These biochemical changes were however amended to their pre-infection values at 16 D.P.I. in Group A in contrast to Group B. These parameters in Group C and Group D remained fairly constant. In conclusion, the infection caused biochemical changes suggestive of liver and kidney dysfunctions, with muscular wasting, which were amended following treatments with Cymelarsan®.Istraživanje je provedeno da bi se odredio učinak melarsenoksid-cisteamin-hidroklorida (Cymelarsan®) na biokemijska obilježja u serumu dvogrbih deva pokusno invadiranih protozoonom Trypanosoma evansi. Pokus je proveden na 20 dvogrbih deva razvrstanih u skupine od A do D. Svaka skupina sadržavala je pet deva. Skupina A bila je invadirana i liječena pripravkom Cymelarsan® u dozi od 0,25 mg/kg tjelesne mase. Skupina B bila invadirana kontrola. Skupina C je bila neinvadirana kontrola dok je skupina D bila neinvadirana, ali je dobivala Cymelarsan®. Jednaka parazitemija (2,4 ± 0,19) bila je ustanovljena nakon prepatentnog razdoblja od svega 4 dana (skupina A i B). Jačina parazitemije značajno je porasla dvadesetog dana nakon invazije (P<0,05), do 210,2 ± 1,81 (skupina A) i 200,2 ± 1,77 (skupina B). U životinja skupine A nije zabilježena parazitemija 32. dana nakon invazije. U skupini B parazitemija je 36. dana poslije invazije iznosila 400,2 ± 2,50. U serumu invadiranih životinja značajno su porasle (P<0,05) vrijednosti alaninaminotransferaze, kreatinina i ukupnog bilirubina dok su se vrijednosti glukoze i ukupnih proteina značajno smanjile (P<0,05). Sve vrijednosti bile su različite u odnosu na 16. dan poslije invazije u životinja skupine A što nije bio slučaj u životinja skupine B. Vrijednosti u serumu životinja skupina C i D ostale su nepromijenjene. Zaključuje se da ustanovljene bikokemijske promjene upućuju na poremećenu funkciju jetre i bubrega te na iscrpljenost mišićja što se značajno popravilo nakon primjene Cymelarsana®
Swift/XRT monitoring of five orbital cycles of LSI +61 303
LSI +61 303 is one of the most interesting high-mass X-ray binaries owing to
its spatially resolved radio emission and its TeV emission, generally
attributed to non-thermal particles in an accretion-powered relativistic jet or
in the termination shock of the relativistic wind of a young pulsar. Also, the
nature of the compact object is still debated. Only LS 5039 and PSR B1259-63
(which hosts a non-accreting millisecond pulsar) have similar characteristics.
We study the X-ray emission from LSI +61 303 covering both short-term and
orbital variability. We also investigate the source spectral properties in the
soft X-ray (0.3-10 keV) energy range. 25 snapshot observations of LSI +61 303
have been collected in 2006 with the XRT instrument on-board the Swift
satellite over a period of four months, corresponding to about five orbital
cycles. Since individual data sets have too few counts for a meaningful
spectral analysis, we extracted a cumulative spectrum. The count rate folded at
the orbital phase shows a clear modulation pattern at the 26.5 days period and
suggests that the X-ray peak occurs around phase 0.65. Moreover, the X-ray
emission appears to be variable on a timescale of ~1 ks. The cumulative
spectrum is well described by an absorbed power-law model, with hydrogen column
density Nh=(5.7+/-0.3)E+21 cm^-2 and photon index 1.78+/-0.05. No accretion
disk signatures, such as an iron line, are found in the spectrum.Comment: Revised to match the A&A versio
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