507 research outputs found
Treatment of renal stones by extracorporeal shockwave lithotripsy - An update
Aim: Despite the extensive experience with minimal invasive stone therapy, there are still different views on the ideal management of renal stones. Materials and Methods: Analysis of the literature includes more than 14,000 patients. We have compared these data with long-term results of two major stone centers in Germany. The results have been compared concerning the anatomical kidney situation, stone size, stone localization and observation time. Results: According to the importance of residual fragments following extracorporeal shock wave lithotripsy (ESWL), we have to distinguish between clinically insignificant residual fragments and clinically significant residual fragments (CIRF). 24 months following ESWL stone passage occurs as a continous process, and if there are no clinical symptoms, any endoscopic procedure should be considered as overtreatment. According to these results, stone-free rates of patients increase in longer follow-up periods. Newer ESWL technology has increased the percentage of CIRF. Conclusion: We consider ESWL in most patients with renal calculi as first-line treatment, except in patients with renal calculi bigger than 30 mm in diameter. Copyright (C) 2001 S. Karger AG, Basel
The operational meaning of min- and max-entropy
We show that the conditional min-entropy Hmin(A|B) of a bipartite state
rho_AB is directly related to the maximum achievable overlap with a maximally
entangled state if only local actions on the B-part of rho_AB are allowed. In
the special case where A is classical, this overlap corresponds to the
probability of guessing A given B. In a similar vein, we connect the
conditional max-entropy Hmax(A|B) to the maximum fidelity of rho_AB with a
product state that is completely mixed on A. In the case where A is classical,
this corresponds to the security of A when used as a secret key in the presence
of an adversary holding B. Because min- and max-entropies are known to
characterize information-processing tasks such as randomness extraction and
state merging, our results establish a direct connection between these tasks
and basic operational problems. For example, they imply that the (logarithm of
the) probability of guessing A given B is a lower bound on the number of
uniform secret bits that can be extracted from A relative to an adversary
holding B.Comment: 12 pages, v2: no change in content, some typos corrected (including
the definition of fidelity in footnote 8), now closer to the published
versio
Leftover Hashing Against Quantum Side Information
The Leftover Hash Lemma states that the output of a two-universal hash
function applied to an input with sufficiently high entropy is almost uniformly
random. In its standard formulation, the lemma refers to a notion of randomness
that is (usually implicitly) defined with respect to classical side
information. Here, we prove a (strictly) more general version of the Leftover
Hash Lemma that is valid even if side information is represented by the state
of a quantum system. Furthermore, our result applies to arbitrary delta-almost
two-universal families of hash functions. The generalized Leftover Hash Lemma
has applications in cryptography, e.g., for key agreement in the presence of an
adversary who is not restricted to classical information processing
Causal Boxes: Quantum Information-Processing Systems Closed under Composition
Complex information-processing systems, for example quantum circuits,
cryptographic protocols, or multi-player games, are naturally described as
networks composed of more basic information-processing systems. A modular
analysis of such systems requires a mathematical model of systems that is
closed under composition, i.e., a network of these objects is again an object
of the same type. We propose such a model and call the corresponding systems
causal boxes.
Causal boxes capture superpositions of causal structures, e.g., messages sent
by a causal box A can be in a superposition of different orders or in a
superposition of being sent to box B and box C. Furthermore, causal boxes can
model systems whose behavior depends on time. By instantiating the Abstract
Cryptography framework with causal boxes, we obtain the first composable
security framework that can handle arbitrary quantum protocols and relativistic
protocols.Comment: 44+24 pages, 16 figures. v3: minor edits based on referee comments,
matches published version up to layout. v2: definition of causality weakened,
new reference
Toward an Algebraic Theory of Systems
We propose the concept of a system algebra with a parallel composition
operation and an interface connection operation, and formalize
composition-order invariance, which postulates that the order of composing and
connecting systems is irrelevant, a generalized form of associativity.
Composition-order invariance explicitly captures a common property that is
implicit in any context where one can draw a figure (hiding the drawing order)
of several connected systems, which appears in many scientific contexts. This
abstract algebra captures settings where one is interested in the behavior of a
composed system in an environment and wants to abstract away anything internal
not relevant for the behavior. This may include physical systems, electronic
circuits, or interacting distributed systems.
One specific such setting, of special interest in computer science, are
functional system algebras, which capture, in the most general sense, any type
of system that takes inputs and produces outputs depending on the inputs, and
where the output of a system can be the input to another system. The behavior
of such a system is uniquely determined by the function mapping inputs to
outputs. We consider several instantiations of this very general concept. In
particular, we show that Kahn networks form a functional system algebra and
prove their composition-order invariance.
Moreover, we define a functional system algebra of causal systems,
characterized by the property that inputs can only influence future outputs,
where an abstract partial order relation captures the notion of "later". This
system algebra is also shown to be composition-order invariant and appropriate
instantiations thereof allow to model and analyze systems that depend on time
A Tight High-Order Entropic Quantum Uncertainty Relation With Applications
We derive a new entropic quantum uncertainty relation involving min-entropy.
The relation is tight and can be applied in various quantum-cryptographic
settings.
Protocols for quantum 1-out-of-2 Oblivious Transfer and quantum Bit
Commitment are presented and the uncertainty relation is used to prove the
security of these protocols in the bounded quantum-storage model according to
new strong security definitions.
As another application, we consider the realistic setting of Quantum Key
Distribution (QKD) against quantum-memory-bounded eavesdroppers. The
uncertainty relation allows to prove the security of QKD protocols in this
setting while tolerating considerably higher error rates compared to the
standard model with unbounded adversaries. For instance, for the six-state
protocol with one-way communication, a bit-flip error rate of up to 17% can be
tolerated (compared to 13% in the standard model).
Our uncertainty relation also yields a lower bound on the min-entropy key
uncertainty against known-plaintext attacks when quantum ciphers are composed.
Previously, the key uncertainty of these ciphers was only known with respect to
Shannon entropy.Comment: 21 pages; editorial changes, additional applicatio
The operational meaning of min- and max-entropy
We show that the conditional min-entropy Hmin(A|B) of a bipartite
state rho_AB is directly related to the maximum achievable overlap
with a maximally entangled state if only local actions on the B-part
of rho_AB are allowed. In the special case where A is classical, this
overlap corresponds to the probability of guessing A given B. In a
similar vein, we connect the conditional max-entropy Hmax(A|B) to the
maximum fidelity of rho_AB with a product state that is completely
mixed on A. In the case where A is classical, this corresponds to the
security of A when used as a secret key in the presence of an
adversary holding B. Because min- and max-entropies are known to
characterize information-processing tasks such as randomness
extraction and state merging, our results establish a direct
connection between these tasks and basic operational problems. For
example, they imply that the (logarithm of the) probability of
guessing A given B is a lower bound on the number of uniform secret
bits that can be extracted from A relative to an adversary holding B
Doppelt negative T-Lymphozyten, löslicher FAS Rezeptor und löslicher FAS Ligand bei Kindern mit häufigen Infektionen
Es wurden 29 Patienten untersucht, die sich wegen häufigen Infektionen im Dr. von Haunerschen Kinderspital vorstellten. Hierbei wurde die prozentuale Verteilung von CD4-, CD8-positiven und doppelt negativen T-Lymphozyten bestimmt. Ebenfalls bestimmt wurden die Plasmaspiegel der Plasmaproteine sFas und sFasL.
Der prozentuale Anteil an DN-T-Zellen lag signifikant über dem der gesunden Kontrollen bei gleichzeitig erniedrigten CD8 positiven Zellen. Es wird angenommen, dass aktivierte T-Lymphozyten über die Zwischenstufe der DN-T-Lymphozyten in Apoptose übergehen, daher könnten diese Befunde Zeichen einer vermehrten Lymphozytenaktivierung von CD8 positiven Zellen sein.
Desweiteren fanden sich in dieser Arbeit Hinweise für eine in der Literatur vorbeschriebene Abhängigkeit von sFas und DN-T-Lymphozyten. Hier jedoch korrelierten niedrige sFas Spiegel mit einem höherem Anteil an DN-T-Lymphozyten, während in der Literatur nach Injektion von sFas bei Mäusen eine Erhöhung von DN-T-Lymphozyten gefunden wurde. Ein Interpretationsversuch der in dieser Arbeit gewonnenen Daten lautet, dass der Körper durch eine Erniedrigung des Spiegels von apoptosehemmenden sFas einen Anstieg des Anteils an DN-T-Zellen nicht noch begünstigen will
Mapping the energy and diffusion landscapes of membrane proteins at the cell surface using high-density single-molecule imaging and Bayesian inference: application to the multi-scale dynamics of glycine receptors in the neuronal membrane
Protein mobility is conventionally analyzed in terms of an effective
diffusion. Yet, this description often fails to properly distinguish and
evaluate the physical parameters (such as the membrane friction) and the
biochemical interactions governing the motion. Here, we present a method
combining high-density single-molecule imaging and statistical inference to
separately map the diffusion and energy landscapes of membrane proteins across
the cell surface at ~100 nm resolution (with acquisition of a few minutes).
When applying these analytical tools to glycine neurotransmitter receptors
(GlyRs) at inhibitory synapses, we find that gephyrin scaffolds act as shallow
energy traps (~3 kBT) for GlyRs, with a depth modulated by the biochemical
properties of the receptor-gephyrin interaction loop. In turn, the inferred
maps can be used to simulate the dynamics of proteins in the membrane, from the
level of individual receptors to that of the population, and thereby, to model
the stochastic fluctuations of physiological parameters (such as the number of
receptors at synapses). Overall, our approach provides a powerful and
comprehensive framework with which to analyze biochemical interactions in
living cells and to decipher the multi-scale dynamics of biomolecules in
complex cellular environments.Comment: 23 pages, 4 figure
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