124 research outputs found
Somatic Hypermutational Status and Gene Repertoire of Immunoglobulin Rearrangements in Chronic Lymphocytic Leukemia
Immunoglobulin molecule is the key component of B cell receptor (BCR), which governs the survival, differentiation and function of normal B lymphocytes, but accumulating data suggest that, in the case of chronic lymphocytic leukaemia (CLL), it is also involved in the pathogenesis and clinical course of the disease. CLL is a malignancy of mature CD5+ CD19+ CD23+ sIgMlow B lymphocytes and is characterized by extremely heterogeneous clinical course, which varies from indolent to rapidly progressive. Somatic hypermutational status of immunoglobulin heavy chain variable genes (IGHV) defines two CLL subtypes, mutated (MâCLL) and unmutated (UâCLL). UâCLL patients suffer from more aggressive disease, characterized by shorter time to treatment, progressionâfree survival and overall survival in comparison to MâCLL patients. Since these correlations are not dependent on the clinical stage and since there is no interconversion between subtypes, IGHV mutational status is currently the most reliable prognostic marker in CLL. Several lines of evidence indicate that both MâCLL and UâCLL arise from an antigenâexperienced cell of origin. Immunogenetic studies have revealed CLLâbiased usage of immunoglobulin variable region genes, as well as the existence of highly homologous, âstereotypedâ BCRs in CLL clones, strongly implying the role of antigenic drive in the development and evolution of the disease
The interacting binary V 393 Scorpii: another clue for Double Periodic Variables
We give a brief report on spectroscopic properties of V 393 Scorpii. H alfa
emission and shape and radial velocity of He I 5875 are modulated with the long
cycle. The long cycle is explained as a relaxation cycle in the circumprimary
disc, that cumulates the mass transferred from the donor until certain
instability produces disc depletion.Comment: 2 pages, 2 figures in encapsulated postscript format. To be published
in Proceedings IAU Symposium No.262, 200
Digging Deeper:Operator Analysis for Optimizing Nonlinearity of Boolean Functions
Boolean functions are mathematical objects with numerous applications in domains like coding theory, cryptography, and telecommunications. Finding Boolean functions with specific properties is a complex combinatorial optimization problem where the search space grows super-exponentially with the number of input variables. One common property of interest is the nonlinearity of Boolean functions. Constructing highly nonlinear Boolean functions is difficult as it is not always known what nonlinearity values can be reached in practice. In this paper, we investigate the effects of the genetic operators for bit-string encoding in optimizing nonlinearity. While several mutation and crossover operators have commonly been used, the link between the genotype they operate on and the resulting phenotype changes is mostly obscure. By observing the range of possible changes an operator can provide, as well as relative probabilities of specific transitions in the objective space, one can use this information to design a more effective combination of genetic operators. The analysis reveals interesting insights into operator effectiveness and indicates how algorithm design may improve convergence compared to an operator-agnostic genetic algorithm
A survey of metaheuristic algorithms for the design of cryptographic Boolean functions
Boolean functions are mathematical objects used in diverse domains and have been actively researched for several decades already. One domain where Boolean functions play an important role is cryptography. There, the plethora of settings one should consider and cryptographic properties that need to be fulfilled makes the search for new Boolean functions still a very active domain. There are several options to construct appropriate Boolean functions: algebraic constructions, random search, and metaheuristics. In this work, we concentrate on metaheuristic approaches and examine the related works appearing in the last 25 years. To the best of our knowledge, this is the first survey work on this topic. Additionally, we provide a new taxonomy of related works and discuss the results obtained. Finally, we finish this survey with potential future research directions.</p
A Survey of Metaheuristic Algorithms for the Design of Cryptographic Boolean Functions
Boolean functions are mathematical objects used in diverse domains and have been actively researched for several decades already. One domain where Boolean functions play an important role is cryptography. There, the plethora of settings one should consider and cryptographic properties that need to be fulfilled makes the search for new Boolean functions still a very active domain. There are several options to construct appropriate Boolean functions: algebraic constructions, random search, and metaheuristics. In this work, we concentrate on metaheuristic approaches and examine the related works appearing in the last 25 years. To the best of our knowledge, this is the first survey work on this topic. Additionally, we provide a new taxonomy of related works and discuss the results obtained. Finally, we finish this survey with potential future research directions
Physical parameters of close binaries QX Andromedae, RW Comae Berenices, MR Delphini, and BD +07{\circ} 3142
Aims. We analyze new multicolor light curves and recently published radial
velocity curves for close binaries QX And, RW Com, MR Del, and BD +07{\circ}
3142 to determine the physical parameters of the components. Methods. The light
curves are analyzed using a binary star model based on Roche geometry to fit
the photometric observations. Spectroscopic parameters, such as the mass ratios
and spectral types, were taken from recent spectroscopic studies of the systems
in question. Results. Our findings provide consistent and reliable sets of
stellar parameters for the four studied binary systems. Of particular interest
is the BD +07{\circ} 3142 system, since this is the first analysis of its light
curves. We find that it is an overcontact binary of W UMa type and W subtype,
and that each component has a large cool spot in the polar region. QX And is an
A subtype, and RW Com a W subtype W UMa binary, and in both systems we find a
bright spot in the neck region between the components. MR Del is a detached
binary with a complex light curve that we could model with two cool spots on
the hotter component.Comment: 10 pages, 4 figures. Accepted for publication by A&
On the Evolution of Boomerang Uniformity in Cryptographic S-boxes
S-boxes are an important primitive that help cryptographic algorithms to be
resilient against various attacks. The resilience against specific attacks can
be connected with a certain property of an S-box, and the better the property
value, the more secure the algorithm. One example of such a property is called
boomerang uniformity, which helps to be resilient against boomerang attacks.
How to construct S-boxes with good boomerang uniformity is not always clear.
There are algebraic techniques that can result in good boomerang uniformity,
but the results are still rare. In this work, we explore the evolution of
S-boxes with good values of boomerang uniformity. We consider three different
encodings and five S-box sizes. For sizes and , we
manage to obtain optimal solutions. For , we obtain optimal
boomerang uniformity for the non-APN function. For larger sizes, the results
indicate the problem to be very difficult (even more difficult than evolving
differential uniformity, which can be considered a well-researched problem).Comment: 15 pages, 3 figures, 4 table
The dynamical stability of W Ursae Majoris-type systems
Theoretical study indicates that a contact binary system would merge into a
rapidly rotating single star due to tidal instability when the spin angular
momentum of the system is more than a third of its orbital angular momentum.
Assuming that W UMa contact binary systems rigorously comply with the Roche
geometry and the dynamical stability limit is at a contact degree of about 70%,
we obtain that W UMa systems might suffer Darwin's instability when their mass
ratios are in a region of about 0.076--0.078 and merge into the fast-rotating
stars. This suggests that the W UMa systems with mass ratio can
not be observed. Meanwhile, we find that the observed W UMa systems with a mass
ratio of about 0.077, corresponding to a contact degree of about 86% would
suffer tidal instability and merge into the single fast-rotating stars. This
suggests that the dynamical stability limit for the observed W UMa systems is
higher than the theoretical value, implying that the observed systems have
probably suffered the loss of angular momentum due to gravitational wave
radiation (GR) or magnetic stellar wind (MSW).Comment: 4 pages, 3 figures, published in MNRAS (2006MNRAS.369.2001
Synthetic Spectra and Light Curves of Interacting Binaries and Exoplanets with Circumstellar Material: SHELLSPEC
Program SHELLSPEC is designed to calculate light-curves, spectra and images
of interacting binaries and extrasolar planets immersed in a moving
circumstellar environment which is optically thin. It solves simple radiative
transfer along the line of sight in moving media. The assumptions include LTE
and optional known state quantities and velocity fields in 3D. Optional
(non)transparent objects such as a spot, disc, stream, jet, ufo, shell or stars
may be defined (embedded) in 3D and their composite synthetic spectrum
calculated. Roche model can be used as a boundary condition for the radiative
transfer. Recently a new model of the reflection effect, dust and Mie
scattering were incorporated into the code.
Aurigae is one of the most mysterious objects on the sky. Prior
modeling of its light-curve assumed dark, inclined, disk of dust with the
central hole to explain the light-curve with a sharp mid-eclipse brightening.
Our model consists of two geometrically thick flared disks. Internal optically
thick disk and external optically thin disk which absorbs and scatters
radiation. Shallow mid-eclipse brightening may result from eclipses by nearly
edge-on flared (dusty or gaseous) disks. Mid-eclipse brightening may also be
due to strong forward scattering and optical properties of the dust which can
have an important effect on the light-curves.
There are many similarities between interacting binary stars and transiting
extrasolar planets. Reflection effect which is briefly reviewed is one of them.
The exact Roche shape and temperature distributions over the surface of all
currently known transiting extrasolar planets have been determined. In some
cases (HAT-P-32b, WASP-12b, WASP-19b) departures from the spherical shape can
reach 7-15%.Comment: 6 pages, 2 figures, to appear in the Proceedings: From Interacting
Binaries to Exoplanets: Essential Modeling Tools, IAU Symposium 282, held in
Tatranska Lomnica, July 201
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