227 research outputs found
New Sources of Gravitational Waves during Inflation
We point out that detectable inflationary tensor modes can be generated by
particle or string sources produced during inflation, consistently with the
requirements for inflation and constraints from scalar fluctuations. We show
via examples that this effect can dominate over the contribution from quantum
fluctuations of the metric, occurring even when the inflationary potential
energy is too low to produce a comparable signal. Thus a detection of tensor
modes from inflation does not automatically constitute a determination of the
inflationary Hubble scale.Comment: 32 pages, 1 figure. v2: JCAP published version; some overestimates
corrected; main results unchange
Information Leakage Games
We consider a game-theoretic setting to model the interplay between attacker
and defender in the context of information flow, and to reason about their
optimal strategies. In contrast with standard game theory, in our games the
utility of a mixed strategy is a convex function of the distribution on the
defender's pure actions, rather than the expected value of their utilities.
Nevertheless, the important properties of game theory, notably the existence of
a Nash equilibrium, still hold for our (zero-sum) leakage games, and we provide
algorithms to compute the corresponding optimal strategies. As typical in
(simultaneous) game theory, the optimal strategy is usually mixed, i.e.,
probabilistic, for both the attacker and the defender. From the point of view
of information flow, this was to be expected in the case of the defender, since
it is well known that randomization at the level of the system design may help
to reduce information leaks. Regarding the attacker, however, this seems the
first work (w.r.t. the literature in information flow) proving formally that in
certain cases the optimal attack strategy is necessarily probabilistic
Evaluation of thyroid hormones in patients with lead poisoning
Background: Each toxic agent results in unique presentations, depending on what neurophysiological changes occur following exposure. Scientific understanding of lead toxicity in the organ systems and at low levels of exposure continues to evolve. However, effects of lead poisoning on the thyroid gland function are controversial. In this descriptive study, changes in thyroid hormones in patients with lead poisoning were compared with patients with opioid addiction and healthy individual who were matched for age and sex.
Methods: In this descriptive study, which was conducted from March 2016 to February 2017 in Loghman Hakim Hospital in Tehran, ninety patients were evaluated using convenient sampling method for lead and thyroid hormones levels. The levels of lead and thyroid hormones were evaluated using standard laboratory method, in thirty male patients with lead poisoning, thirty male patients with opioid addiction referring to addiction treatment center and thirty healthy male referring to a blood donation center who were matcAhed for age. Thyroid function parameters in patients with lead toxicity were compared with those of control groups.
Results: The lead level in the lead toxicity group was 57.5±23.5 µg/dl, in the first control group with opium addiction 7.8±3.8 µg/dl and in the healthy male referring to a blood donation center, 5.9±9 µg/dl. Thyroid stimulating hormone (TSH) was significantly lower in patients with lead poisoning (0.2±0.01 Milli-International Units Per Liter (mIU/L) than in the patients with opioid addiction (2.4±1/05 mIU/L) and healthy male referring to a blood donation center (2.3±0.01 mIU/L) (P= 0.04), and thyroxine hormone (T4) was significantly higher in patients with lead poisoning (17.8±2.6 µg/dl) than in the patients with opioid addiction (8.8±1/9 µg/dl) and healthy male referring to a blood donation center (7.4±3.5 µg/dl) (P= 0.02).
Conclusion: Lead toxicity has an effect on thyroid function and it reduces thyroid stimulating hormone and increases thyroxin levels. Clinicians should be aware of the potential hazardous effects of lead on the thyroid and mechanisms through which lead causes these effects on thyroid function need to be elucidated.
Keywords: lead poisoning, opium, thyroid function test
Beyond Logarithmic Corrections to Cardy Formula
As shown by Cardy modular invariance of the partition function of a given
unitary non-singular 2d CFT with left and right central charges c_L and c_R,
implies that the density of states in a microcanonical ensemble, at excitations
Delta and Delta-bar and in the saddle point approximation, is
\rho_0(\Delta,\bar\Delta;c_L, c_R)=c_L c_R
\exp(2\pi\sqrt{{c_L\Delta}/{6}})\exp(2\pi\sqrt{{c_R\bar\Delta}/{6}}). In this
paper, we extend Cardy's analysis and show that in the saddle point
approximation and up to contributions which are exponentially suppressed
compared to the leading Cardy's result, the density of states takes the form
\rho(\Delta,\bar\Delta; c_L,c_R)= f(c_L\Delta)
f(c_R\bar\Delta)\rho_0(\Delta,\bar\Delta; c_L, c_R), for a function f(x) which
we specify. In particular, we show that (i) \rho (\Delta,\bar\Delta; c_L, c_R)
is the product of contributions of left and right movers and hence, to this
approximation, the partition function of any modular invariant, non-singular
unitary 2d CFT is holomorphically factorizable and (ii) \rho(\Delta,\bar\Delta;
c_L, c_R)/(c_Lc_R) is only a function of and . In
addition, treating \rho(\Delta,\bar\Delta; c_L, c_R) as the density of states
of a microcanonical ensemble, we compute the entropy of the system in the
canonical counterpart and show that the function f(x) is such that the
canonical entropy, up to exponentially suppressed contributions, is simply
given by the Cardy's result \ln\rho_0(\Delta,\bar\Delta; c_L, c_R).Comment: 30 pages, no figures; v2: minor improvements, one reference added,
v3: minor corrections to match the published versio
Force transmission in a packing of pentagonal particles
We perform a detailed analysis of the contact force network in a dense
confined packing of pentagonal particles simulated by means of the contact
dynamics method. The effect of particle shape is evidenced by comparing the
data from pentagon packing and from a packing with identical characteristics
except for the circular shape of the particles. A counterintuitive finding of
this work is that, under steady shearing, the pentagon packing develops a lower
structural anisotropy than the disk packing. We show that this weakness is
compensated by a higher force anisotropy, leading to enhanced shear strength of
the pentagon packing. We revisit "strong" and "weak" force networks in the
pentagon packing, but our simulation data provide also evidence for a large
class of "very weak" forces carried mainly by vertex-to-edge contacts. The
strong force chains are mostly composed of edge-to-edge contacts with a marked
zig-zag aspect and a decreasing exponential probability distribution as in a
disk packing
Credit card fraud detection using asexual reproduction optimization
Purpose – The best algorithm that was implemented on this Brazilian dataset was artificial immune system (AIS)
algorithm. But the time and cost of this algorithm are high. Using asexual reproduction optimization (ARO) algorithm,
the authors achieved better results in less time. So the authors achieved less cost in a shorter time. Their framework
addressed the problems such as high costs and training time in credit card fraud detection. This simple and effective
approach has achieved better results than the best techniques implemented on our dataset so far. The purpose of this
paper is to detect credit card fraud using ARO.
Design/methodology/approach – In this paper, the authors used ARO algorithm to classify the bank transactions
into fraud and legitimate. ARO is taken from asexual reproduction. Asexual reproduction refers to a kind of production in
which one parent produces offspring identical to herself. In ARO algorithm, an individual is shown by a vector of variables.
Each variable is considered as a chromosome. A binary string represents a chromosome consisted of genes. It is supposed
that every generated answer exists in the environment, and because of limited resources, only the best solution can remain
alive. The algorithm starts with a random individual in the answer scope. This parent reproduces the offspring named bud.
Either the parent or the offspring can survive. In this competition, the one which outperforms in fitness function remains
alive. If the offspring has suitable performance,it will be the next parent, and the current parent becomes obsolete.Otherwise,
the offspring perishes, and the present parent survives. The algorithm recurs until the stop condition occurs.
Findings – Results showed that ARO had increased the AUC (i.e. area under a receiver operating characteristic (ROC)
curve), sensitivity, precision, specificity and accuracy by 13%, 25%, 56%, 3% and 3%, in comparison with AIS,
respectively. The authors achieved a high precision value indicating that if ARO detects a record as a fraud, with a high
probability, it is a fraud one. Supporting a real-time fraud detection system is another vital issue. ARO outperforms AIS
not only in the mentioned criteria, but also decreases the training time by 75% in comparison with the AIS, which is a
significant figure.
Originality/value – In this paper, the authors implemented the ARO in credit card fraud detection. The authors
compared the results with those of the AIS, which was one of the best methods ever implemented on the benchmark
dataset. The chief focus of the fraud detection studies is finding the algorithms that can detect legal transactions from
the fraudulent ones with high detection accuracy in the shortest time and at a low cost. That ARO meets all these
demands
Near the horizon of 5D black rings
For the five dimensional N=2 black rings, we study the supersymmetry
enhancement and identify the global supergroup of the near horizon geometry. We
show that the global part of the supergroup is OSp(4*|2)X U(1) which is similar
to the small black string. We show that results obtained by applying the
entropy function formalism, the c-extremization approach and the Brown-Henneaux
method to the black ring solution are in agreement with the microscopic entropy
calculation.Comment: 26 pages, version to appear in JHEP, the near horizon superalgebra is
corrected, discussion on small black ring is discarded, Brown-Henneaux
approach to large black ring is adde
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