2,045,660 research outputs found
From Structure to Function in Open Ionic Channels
We consider a simple working hypothesis that all permeation properties of
open ionic channels can be predicted by understanding electrodiffusion in fixed
structures, without invoking conformation changes, or changes in chemical
bonds. We know, of course, that ions can bind to specific protein structures,
and that this binding is not easily described by the traditional electrostatic
equations of physics textbooks, that describe average electric fields, the
so-called `mean field'. The question is which specific properties can be
explained just by mean field electrostatics and which cannot. I believe the
best way to uncover the specific chemical properties of channels is to invoke
them as little as possible, seeking to explain with mean field electrostatics
first. Then, when phenomena appear that cannot be described that way, by the
mean field alone, we turn to chemically specific explanations, seeking the
appropriate tools (of electrochemistry, Langevin, or molecular dynamics, for
example) to understand them. In this spirit, we turn now to the structure of
open ionic channels, apply the laws of electrodiffusion to them, and see how
many of their properties we can predict just that way.Comment: Nearly final version of publicatio
Waterbath Calibrator with Nine Channels Sensor
Water bath is a laboratory equipment that contains water or special liquid that can maintain the temperature under certain conditions during the specified time interval. For this reason, calibration is needed so that the temperature in the chamber waterbath is stable or not. calibration is carried out by comparing measuring instruments and measuring materials to be calibrated to traceable standards that are traceable to national and / or International standards.
Based on the results of the identification of the problems mentioned above, the author makes a waterbath calibrator entitled "Waterbath Calibrator (9 channel)" which is very practical, and easy to operate. .This calibration tool uses a K type thermocouple sensor and also the output is displayed to the character LCD to make it easier for users to retrieve data, the reason for choosing a thermocouple sensor is because the error rate is +/- 1,1C while the LM35 is +/- 1,4C.
The thermocouple temperature sensor can detect the chamber temperature quite well where the biggest error is obtained with a comparator of 2%, and the lowest error is 0%
Oblivious channels
Let C = {x_1,...,x_N} \subset {0,1}^n be an [n,N] binary error correcting
code (not necessarily linear). Let e \in {0,1}^n be an error vector. A codeword
x in C is said to be "disturbed" by the error e if the closest codeword to x +
e is no longer x. Let A_e be the subset of codewords in C that are disturbed by
e. In this work we study the size of A_e in random codes C (i.e. codes in which
each codeword x_i is chosen uniformly and independently at random from
{0,1}^n). Using recent results of Vu [Random Structures and Algorithms 20(3)]
on the concentration of non-Lipschitz functions, we show that |A_e| is strongly
concentrated for a wide range of values of N and ||e||.
We apply this result in the study of communication channels we refer to as
"oblivious". Roughly speaking, a channel W(y|x) is said to be oblivious if the
error distribution imposed by the channel is independent of the transmitted
codeword x. For example, the well studied Binary Symmetric Channel is an
oblivious channel.
In this work, we define oblivious and partially oblivious channels and
present lower bounds on their capacity. The oblivious channels we define have
connections to Arbitrarily Varying Channels with state constraints.Comment: Submitted to the IEEE International Symposium on Information Theory
(ISIT) 200
Quantum MERA Channels
Tensor networks representations of many-body quantum systems can be described
in terms of quantum channels. We focus on channels associated with the
Multi-scale Entanglement Renormalization Ansatz (MERA) tensor network that has
been recently introduced to efficiently describe critical systems. Our approach
allows us to compute the MERA correspondent to the thermodynamic limit of a
critical system introducing a transfer matrix formalism, and to relate the
system critical exponents to the convergence rates of the associated channels.Comment: 4 pages, 2 figure
Bosonic Memory Channels
We discuss a Bosonic channel model with memory effects. It relies on a
multi-mode squeezed (entangled) environment's state. The case of lossy Bosonic
channels is analyzed in detail. We show that in the absence of input energy
constraints the memory channels are equivalent to their memoryless
counterparts. In the case of input energy constraint we provide lower and upper
bounds for the memory channel capacity.Comment: 6 pages, 2 figure
Quantum Feedback Channels
In Shannon information theory the capacity of a memoryless communication
channel cannot be increased by the use of feedback. In quantum information
theory the no-cloning theorem means that noiseless copying and feedback of
quantum information cannot be achieved. In this paper, quantum feedback is
defined as the unlimited use of a noiseless quantum channel from receiver to
sender. Given such quantum feedback, it is shown to provide no increase in the
entanglement--assisted capacities of a memoryless quantum channel, in direct
analogy to the classical case. It is also shown that in various cases of
non-assisted capacities, feedback may increase the capacity of memoryless
quantum channels.Comment: 5 pages, requires IEEEtran.cls, expanded, proofs added, references
adde
Quantum broadcast channels
We consider quantum channels with one sender and two receivers, used in
several different ways for the simultaneous transmission of independent
messages. We begin by extending the technique of superposition coding to
quantum channels with a classical input to give a general achievable region. We
also give outer bounds to the capacity regions for various special cases from
the classical literature and prove that superposition coding is optimal for a
class of channels. We then consider extensions of superposition coding for
channels with a quantum input, where some of the messages transmitted are
quantum instead of classical, in the sense that the parties establish bipartite
or tripartite GHZ entanglement. We conclude by using state merging to give
achievable rates for establishing bipartite entanglement between different
pairs of parties with the assistance of free classical communication.Comment: 15 pages; IEEE Trans. Inform. Theory, vol. 57, no. 10, October 201
Boosted Higgs Channels
In gluon fusion both a modified top Yukawa and new colored particles can
alter the cross section. However in a large set of composite Higgs models and
in realistic areas of the MSSM parameter space, these two effects can conspire
and hide new physics in a Standard Model-like inclusive cross section. We first
show that it is possible to break this degeneracy in the couplings by demanding
a boosted Higgs recoiling against a high- jet. Subsequently we propose an
analysis based on this idea in the channels. This
measurement allows an alternative determination of the important top Yukawa
besides the channel.Comment: 4 pages, 2 figures. To appear in the proceedings of the 27th
Rencontres the Blois on Particle Physics and Cosmology, May 31 - June 05,
201
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