398 research outputs found
Distributed classifier based on genetically engineered bacterial cell cultures
We describe a conceptual design of a distributed classifier formed by a
population of genetically engineered microbial cells. The central idea is to
create a complex classifier from a population of weak or simple classifiers. We
create a master population of cells with randomized synthetic biosensor
circuits that have a broad range of sensitivities towards chemical signals of
interest that form the input vectors subject to classification. The randomized
sensitivities are achieved by constructing a library of synthetic gene circuits
with randomized control sequences (e.g. ribosome-binding sites) in the front
element. The training procedure consists in re-shaping of the master population
in such a way that it collectively responds to the "positive" patterns of input
signals by producing above-threshold output (e.g. fluorescent signal), and
below-threshold output in case of the "negative" patterns. The population
re-shaping is achieved by presenting sequential examples and pruning the
population using either graded selection/counterselection or by
fluorescence-activated cell sorting (FACS). We demonstrate the feasibility of
experimental implementation of such system computationally using a realistic
model of the synthetic sensing gene circuits.Comment: 31 pages, 9 figure
Anapole Moment and Other Constraints on the Strangeness Conserving Hadronic Weak Interaction
Standard analyses of low-energy NN and nuclear parity-violating observables
have been based on a pi-, rho-, and omega-exchange model capable of describing
all five independent s-p partial waves. Here a parallel analysis is performed
for the one-body, exchange-current, and nuclear polarization contributions to
the anapole moments of 133Cs and 205Tl. The resulting constraints are not
consistent, though there remains some degree of uncertainty in the nuclear
structure analysis of the atomic moments.Comment: Revtex, 10 pages, 1 figur
Monomeric Bistability and the Role of Autoloops in Gene Regulation
Genetic toggle switches are widespread in gene regulatory networks (GRN). Bistability, namely the ability to choose among two different stable states, is an essential feature of switching and memory devices. Cells have many regulatory circuits able to provide bistability that endow a cell with efficient and reliable switching between different physiological modes of operation. It is often assumed that negative feedbacks with cooperative binding (i.e. the formation of dimers or multimers) are a prerequisite for bistability. Here we analyze the relation between bistability in GRN under monomeric regulation and the role of autoloops under a deterministic setting. Using a simple geometric argument, we show analytically that bistability can also emerge without multimeric regulation, provided that at least one regulatory autoloop is present
Pertambangan di Kawasan Konservasi: Permasalahan Regulasi dan Koordinasi
Informasi dan klaim tentang berlangsungnya kegiatan pertambangan di hutan konservasi dapat dengan mudah kita jumpai. Salah satunya, Komisi Pemberantasan Korupsi (KPK) dalam presentasi tentang koordinasi dan supervisi pengelolaan mineral dan batu bara di 19 provinsi pada akhir 2014, menyatakan bahwa izin pertambangan di kawasan hutan konservasi mencapai 1,37 juta hektar (KPK, 2014)
Comments on Non-Commutative Phenomenology
It is natural to ask whether non-commutative geometry plays a role in four
dimensional physics. By performing explicit computations in various toy models,
we show that quantum effects lead to violations of Lorentz invariance at the
level of operators of dimension three or four. The resulting constraints are
very stringent.Comment: Correction of an error in the U(1) and U(N) calculation leads to
stronger limits than those given previously Clarifying comments and reference
adde
Dynamically Driven Renormalization Group Applied to Sandpile Models
The general framework for the renormalization group analysis of
self-organized critical sandpile models is formulated. The usual real space
renormalization scheme for lattice models when applied to nonequilibrium
dynamical models must be supplemented by feedback relations coming from the
stationarity conditions. On the basis of these ideas the Dynamically Driven
Renormalization Group is applied to describe the boundary and bulk critical
behavior of sandpile models. A detailed description of the branching nature of
sandpile avalanches is given in terms of the generating functions of the
underlying branching process.Comment: 18 RevTeX pages, 5 figure
The Off-diagonal Goldberger-Treiman Relation and Its Discrepancy
We study the off-diagonal Goldberger-Treiman relation (ODGTR) and its
discrepancy (ODGTD) in the N, Delta, pi sector through O(p^2) using heavy
baryon chiral perturbation theory. To this order, the ODGTD and axial vector N
to Delta transition radius are determined solely by low energy constants. Loop
corrections appear at O(p^4). For low-energy constants of natural size, the
ODGTD would represent a ~ 2% correction to the ODGTR. We discuss the
implications of the ODGTR and ODGTD for lattice and quark model calculations of
the transition form factors and for parity-violating electroexcitation of the
Delta.Comment: 11 pages, 1 eps figur
Boolean network model predicts cell cycle sequence of fission yeast
A Boolean network model of the cell-cycle regulatory network of fission yeast
(Schizosaccharomyces Pombe) is constructed solely on the basis of the known
biochemical interaction topology. Simulating the model in the computer,
faithfully reproduces the known sequence of regulatory activity patterns along
the cell cycle of the living cell. Contrary to existing differential equation
models, no parameters enter the model except the structure of the regulatory
circuitry. The dynamical properties of the model indicate that the biological
dynamical sequence is robustly implemented in the regulatory network, with the
biological stationary state G1 corresponding to the dominant attractor in state
space, and with the biological regulatory sequence being a strongly attractive
trajectory. Comparing the fission yeast cell-cycle model to a similar model of
the corresponding network in S. cerevisiae, a remarkable difference in
circuitry, as well as dynamics is observed. While the latter operates in a
strongly damped mode, driven by external excitation, the S. pombe network
represents an auto-excited system with external damping.Comment: 10 pages, 3 figure
Parity-Violating Interaction Effects I: the Longitudinal Asymmetry in pp Elastic Scattering
The proton-proton parity-violating longitudinal asymmetry is calculated in
the lab-energy range 0--350 MeV, using a number of different, latest-generation
strong-interaction potentials--Argonne V18, Bonn-2000, and Nijmegen-I--in
combination with a weak-interaction potential consisting of rho- and
omega-meson exchanges--the model known as DDH. The complete scattering problem
in the presence of parity-conserving, including Coulomb, and parity-violating
potentials is solved in both configuration- and momentum-space. The predicted
parity-violating asymmetries are found to be only weakly dependent upon the
input strong-interaction potential adopted in the calculation. Values for the
rho- and omega-meson weak coupling constants and
are determined by reproducing the measured asymmetries at 13.6 MeV, 45 MeV, and
221 MeV.Comment: 24 pages, 8 figures, submitted to Physical Review
Gateway vectors for efficient artificial gene assembly in vitro and expression in yeast Saccharomyces cerevisiae
Peer reviewedPublisher PD
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