5,907 research outputs found
Sainfoin – New Data on Anthelmintic Effects and Production in Sheep and Goats
Gastrointestinal nematodes (GIN) are one of the most important problems affecting health and therefore performance and welfare in small ruminant husbandry. The control of these parasites in the past strongly relied on the repeated use of anthelmintic drugs. This has led to nematode populations which are resistant to most of the currently available anthelmintics. Furthermore customer’s demands for organic and residue free animal products are increasing. The aforementioned problems have given a strong impetus for the development of new non-chemical strategies to control GIN. Previous research has pointed out the anthelmintic potential of sainfoin (Onobrychis viciifolia) and other tanniferous (CT) feed sources in goats and lambs infected with GIN. A recent Swiss experiment focussed on the use of sainfoin and field bean (Vicia faba, cv. Scirocco) as single CT sources as well as in combination for additional synergic effects, to reduce periparturient GIN egg rise of ewes in late gestation and early lactation. Another experiment with Alpine goats concentrated on the influence of sainfoin on milk performance and cheese quality. The results of these experiments will be presented and discussed in connection with previous knowledge on (i) anthelmintic effects of sainfoin and (ii) the influence of sainfoin administration on performance
Efficient One-Way Secret-Key Agreement and Private Channel Coding via Polarization
We introduce explicit schemes based on the polarization phenomenon for the
tasks of one-way secret key agreement from common randomness and private
channel coding. For the former task, we show how to use common randomness and
insecure one-way communication to obtain a strongly secure key such that the
key construction has a complexity essentially linear in the blocklength and the
rate at which the key is produced is optimal, i.e., equal to the one-way
secret-key rate. For the latter task, we present a private channel coding
scheme that achieves the secrecy capacity using the condition of strong secrecy
and whose encoding and decoding complexity are again essentially linear in the
blocklength.Comment: 18.1 pages, 2 figures, 2 table
Quantum turbulence at finite temperature: the two-fluids cascade
To model isotropic homogeneous quantum turbulence in superfluid helium, we
have performed Direct Numerical Simulations (DNS) of two fluids (the normal
fluid and the superfluid) coupled by mutual friction. We have found evidence of
strong locking of superfluid and normal fluid along the turbulent cascade, from
the large scale structures where only one fluid is forced down to the vorticity
structures at small scales. We have determined the residual slip velocity
between the two fluids, and, for each fluid, the relative balance of inertial,
viscous and friction forces along the scales. Our calculations show that the
classical relation between energy injection and dissipation scale is not valid
in quantum turbulence, but we have been able to derive a temperature--dependent
superfluid analogous relation. Finally, we discuss our DNS results in terms of
the current understanding of quantum turbulence, including the value of the
effective kinematic viscosity
Linking Classical and Quantum Key Agreement: Is There "Bound Information"?
After carrying out a protocol for quantum key agreement over a noisy quantum
channel, the parties Alice and Bob must process the raw key in order to end up
with identical keys about which the adversary has virtually no information. In
principle, both classical and quantum protocols can be used for this
processing. It is a natural question which type of protocols is more powerful.
We prove for general states but under the assumption of incoherent
eavesdropping that Alice and Bob share some so-called intrinsic information in
their classical random variables, resulting from optimal measurements, if and
only if the parties' quantum systems are entangled. In addition, we provide
evidence that the potentials of classical and of quantum protocols are equal in
every situation. Consequently, many techniques and results from quantum
information theory directly apply to problems in classical information theory,
and vice versa. For instance, it was previously believed that two parties can
carry out unconditionally secure key agreement as long as they share some
intrinsic information in the adversary's view. The analysis of this purely
classical problem from the quantum information-theoretic viewpoint shows that
this is true in the binary case, but false in general. More explicitly, bound
entanglement, i.e., entanglement that cannot be purified by any quantum
protocol, has a classical counterpart. This "bound intrinsic information"
cannot be distilled to a secret key by any classical protocol. As another
application we propose a measure for entanglement based on classical
information-theoretic quantities.Comment: Accepted for Crypto 2000. 17 page
Strong Secrecy for Multiple Access Channels
We show strongly secret achievable rate regions for two different wiretap
multiple-access channel coding problems. In the first problem, each encoder has
a private message and both together have a common message to transmit. The
encoders have entropy-limited access to common randomness. If no common
randomness is available, then the achievable region derived here does not allow
for the secret transmission of a common message. The second coding problem
assumes that the encoders do not have a common message nor access to common
randomness. However, they may have a conferencing link over which they may
iteratively exchange rate-limited information. This can be used to form a
common message and common randomness to reduce the second coding problem to the
first one. We give the example of a channel where the achievable region equals
zero without conferencing or common randomness and where conferencing
establishes the possibility of secret message transmission. Both coding
problems describe practically relevant networks which need to be secured
against eavesdropping attacks.Comment: 55 page
Characteristic velocities of stripped-envelope core-collapse supernova cores
The velocity of the inner ejecta of stripped-envelope core-collapse
supernovae (CC-SNe) is studied by means of an analysis of their nebular
spectra. Stripped-envelope CC-SNe are the result of the explosion of bare cores
of massive stars ( M), and their late-time spectra are
typically dominated by a strong [O {\sc i}] 6300, 6363 emission
line produced by the innermost, slow-moving ejecta which are not visible at
earlier times as they are located below the photosphere. A characteristic
velocity of the inner ejecta is obtained for a sample of 56 stripped-envelope
CC-SNe of different spectral types (IIb, Ib, Ic) using direct measurements of
the line width as well as spectral fitting. For most SNe, this value shows a
small scatter around 4500 km s. Observations ( days) of
stripped-envelope CC-SNe have revealed a subclass of very energetic SNe, termed
broad-lined SNe (BL-SNe) or hypernovae, which are characterised by broad
absorption lines in the early-time spectra, indicative of outer ejecta moving
at very high velocity (). SNe identified as BL in the early phase
show large variations of core velocities at late phases, with some having much
higher and some having similar velocities with respect to regular CC-SNe. This
might indicate asphericity of the inner ejecta of BL-SNe, a possibility we
investigate using synthetic three-dimensional nebular spectra.Comment: 14 pages, 10 figures, MNRAS accepte
Biochemistry and functional aspects of human glandular kallikreins
Human urinary kallikrein was purified by gel filtration on Sephacryl S-200 and affinity chromatography on aprotinin-Sepharose, followed by ion exchange chromatography on DEAE-Sepharose. In dodecylsulfate gel electrophoresis two protein bands with molecular weights of 41,000 and 34,000 were separated. The amino acid composition and the carbohydrate content of the kallikrein preparation were determined; isoleucine was identified as the only aminoterminal amino acid. The bimolecular velocity constant for the inhibition by diisopropyl fluorophosphate was determined as 9±2 l mol–1 min–1. The hydrolysis of a number of substrates was investigated and AcPheArgOEt was found to be the most sensitive substrate for human urinary kallikrein. Using this substrate an assay method for kallikrein in human urine was developed.
It was shown by radioimmunoassay that pig pancreatic kallikrein can be absorbed in the rat intestinal tract. Furthermore, in dogs the renal excretion of glandular kallikrein from blood was demonstrated by radioimmunological methods
Secret Sharing over Fast-Fading MIMO Wiretap Channels
Secret sharing over the fast-fading MIMO wiretap channel is considered. A
source and a destination try to share secret information over a fast-fading
MIMO channel in the presence of a wiretapper who also makes channel
observations that are different from but correlated to those made by the
destination. An interactive authenticated unrestricted public channel is also
available for use by the source and destination in the secret sharing process.
This falls under the "channel-type model with wiretapper" considered by
Ahlswede and Csiszar. A minor extension of their result (to continuous channel
alphabets) is employed to evaluate the key capacity of the fast-fading MIMO
wiretap channel. The effects of spatial dimensionality provided by the use of
multiple antennas at the source, destination, and wiretapper are then
investigated.Comment: Revision submitted to EURASIP Journal on Wireless Communications and
Networking, Special Issue on Wireless Physical Layer Security, Sept. 2009.
v.3: Fixes to proofs. Matthieu Bloch added as co-author for contributions to
proof
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