1,035 research outputs found
Possible Involvement of Endothelin Peptides and L-Arginine-Nitric Oxide Pathway on the Effect of Endotoxin in the Rabbit Isolated Perfused Kidney
Escherichia coli endotoxin (LPS) when infused through the renal
artery of the rabbit isolated perfused kidney prepared as constant
pressure mode, caused a decrease in flow rate and kidney weight
indicating its primary vasoconstrictor effect. This effect was
predominant in kidneys from rabbits pretreated with LPS. Endothelin-1
at a concentration of 10−10 M and big endothelin-1 at a concentration
of 10−8 M produced equal vasoconstrictor effects in kidney. Addition
of endotheHn converting enzyme inhibitor, phosphoramidon, to the
perfusion medium at a concentration of 10−6 M caused a reduction in
the effects of both LPS and big ET-1 without altering the
vasoconstrictor effect of ETol. However, addition of methylene blue
(10−5 M), a soluble guanylate cyclase inhibitor and
NG-nitro-L-arginine-methyl ester (10−6 M) to the perfusion medium
caused a potentiation in the vasoconstrictor effect of LPS.
Indomethacin at a concentration of 10−6 M did not alter the effect of
LPS. These results were taken as evidence for the participation of
endothelin peptides and the L-arginine-nitric oxide pathway in the
effect ofLPS in rabbit isolated perfused kidney
New oscillation criteria for third-order differential equations with bounded and unbounded neutral coefficients
This paper examines the oscillatory behavior of solutions to a class of thirdorder differential equations with bounded and unbounded neutral coefficients. Sufficient conditions for all solutions to be oscillatory are given. Some examples are considered to illustrate the main results and suggestions for future research are also included
Tc-Glutathione Complex (Tc -GSH) : Labelling, Chemical Characterization and Biodistribution in Rats
The chemical structure of 99mTc-GSH has been estabilished using the 99Tc
isotope.
Labeling of glutathione with technetium in the presence of stanous chloride gave a high yield
result. In a comparative study between 99Tc
and 99Tc
glutathione, the Tc-GSH complex obtained
was purified and characterized by uv, visible spectroscopy, HPLC, Biogel chromatography, mass
and NMR spectroscopy. Stoichiometric analysis showed a 2 : 1 molar ratio of GSH/Tc for the
reaction. The molecular mass assessed by mass spectroscopy was 727 Da corresponding to an
oxo(bis) glutathione technetate. NMR studies demonstrated that each glutathione molecule was
coordinated to technetium via cysteinyl sulfur and nitrogen atoms. The biodistribution of the
complex was studied in normal rats. Blood clearance was rapid during the first hour involving a
biexponential curve ( t1/2
(1) : 50 min, t1/2
(2) : 400 min ). No radioactive accumulation was found in
any specific organ except kidney and bladder. All the activity excreted was found unchanged in
urine. In conclusion, Tc-GSH displayed an anionic dimer form as GSH-Tc-GSH. We assume that the
complex is a tetradentate (2N,2S) complex containing a pentavalent technetium coordinated by two
thiol and nitrogen atoms of both GSH ligands, and an apical oxo group
Question Answering: CNLP at the TREC-10 Question Answering Track
This paper describes the retrieval experiments for the main task and list task of the TREC-10 question answering track. The question answering system described automatically finds answers to questions in a large document collection. The system uses a two-stage retrieval approach to answer finding based on matching of named entities, linguistic patterns, and keywords. In answering a question, the system carries out a detailed query analysis that produces a logical query representation, an indication of the question focus, and answer clue words
Question Answering: CNLP at the TREC-2002 Question Answering Track
This paper describes the retrieval experiments for the main task and list task of the TREC-2002 question-answering track. The question answering system described automatically finds answers to questions in a large document collection. The system uses a two-stage retrieval approach to answer finding based on matching of named entities, linguistic patterns, keywords, and the use of a new inference module. In answering a question, the system carries out a detailed query analysis that produces a logical query representation, an indication of the question focus, and answer clue words
A General Security Approach for Soft-information Decoding against Smart Bursty Jammers
Malicious attacks such as jamming can cause significant disruption or
complete denial of service (DoS) to wireless communication protocols. Moreover,
jamming devices are getting smarter, making them difficult to detect. Forward
error correction, which adds redundancy to data, is commonly deployed to
protect communications against the deleterious effects of channel noise.
Soft-information error correction decoders obtain reliability information from
the receiver to inform their decoding, but in the presence of a jammer such
information is misleading and results in degraded error correction performance.
As decoders assume noise occurs independently to each bit, a bursty jammer will
lead to greater degradation in performance than a non-bursty one. Here we
establish, however, that such temporal dependencies can aid inferences on which
bits have been subjected to jamming, thus enabling counter-measures. In
particular, we introduce a pre-decoding processing step that updates
log-likelihood ratio (LLR) reliability information to reflect inferences in the
presence of a jammer, enabling improved decoding performance for any soft
detection decoder. The proposed method requires no alteration to the decoding
algorithm. Simulation results show that the method correctly infers a
significant proportion of jamming in any received frame. Results with one
particular decoding algorithm, the recently introduced ORBGRAND, show that the
proposed method reduces the block-error rate (BLER) by an order of magnitude
for a selection of codes, and prevents complete DoS at the receiver.Comment: Accepted for GLOBECOM 2022 Workshops. Contains 7 pages and 7 figure
Possible evolution of dim radio quiet neutron star 1E 1207.4-5209 based on a B-decay model
Dim radio-quiet neutron star (DRQNS) 1E 1207.4-5209 is one of the most
heavily examined isolated neutron stars. Wide absorption lines were observed in
its spectrum obtained by both XMM-Newton and Chandra X-ray satellites. These
absorption lines can be interpreted as a principal frequency centered at 0.7
keV and its harmonics at 1.4, 2.1 and possibly 2.8 keV. The principal line can
be formed by resonant proton cyclotron scattering leading to a magnetic field
which is two orders of magnitude larger than the perpendicular component of the
surface dipole magnetic field (B) found from the rotation period (P) and the
time rate of change in the rotation period (\.{P}) of 1E 1207.4-5209. Besides,
age of the supernova remnant (SNR) G296.5+10.0 which is physically connected to
1E 1207.4-5209 is two orders of magnitude smaller than the characteristic age
(=P/2\.{P}) of the neutron star. These huge differences between the
magnetic field values and the ages can be explained based on a B-decay model.
If the decay is assumed to be exponential, the characteristic decay time turns
out to be several thousand years which is three orders of magnitude smaller
than the characteristic decay time of radio pulsars represented in an earlier
work. The lack of detection of radio emission from DRQNSs and the lack of point
sources and pulsar wind nebulae in most of the observed SNRs can also be partly
explained by such a very rapid exponential decay. The large difference between
the characteristic decay times of DRQNSs and radio pulsars must be related to
the differences in the magnetic fields, equation of states and masses of these
isolated neutron stars.Comment: 13 pages, 1 figur
- …