734 research outputs found
Quasisolitons in self-diffusive excitable systems, or Why asymmetric diffusivity does not violate the Second Law
Solitons, defined as nonlinear waves which can reflect from boundaries or
transmit through each other, are found in conservative, fully integrable
systems. Similar phenomena, dubbed quasi-solitons, have been observed also in
dissipative, "excitable" systems, either at finely tuned parameters (near a
bifurcation) or in systems with cross-diffusion. Here we demonstrate that
quasi-solitons can be robustly observed in excitable systems with excitable
kinetics and with self-diffusion only. This includes quasi-solitons of fixed
shape (like KdV solitons) or envelope quasi-solitons (like NLS solitons). This
can happen in systems with more than two components, and can be explained by
effective cross-diffusion, which emerges via adiabatic elimination of a fast
but diffusing component. We describe here a reduction procedure can be used for
the search of complicated wave regimes in multi-component, stiff systems by
studying simplified, soft systems.Comment: 11 pages, 2 figures, as accepted to Scientific Reports on 2016/07/0
Pursuit-evasion predator-prey waves in two spatial dimensions
We consider a spatially distributed population dynamics model with excitable
predator-prey dynamics, where species propagate in space due to their taxis
with respect to each other's gradient in addition to, or instead of, their
diffusive spread. Earlier, we have described new phenomena in this model in one
spatial dimension, not found in analogous systems without taxis: reflecting and
self-splitting waves. Here we identify new phenomena in two spatial dimensions:
unusual patterns of meander of spirals, partial reflection of waves, swelling
wavetips, attachment of free wave ends to wave backs, and as a result, a novel
mechanism of self-supporting complicated spatio-temporal activity, unknown in
reaction-diffusion population models.Comment: 15 pages, 15 figures, submitted to Chao
Soliton-like phenomena in one-dimensional cross-diffusion systems: a predator-prey pursuit and evasion example
We have studied properties of nonlinear waves in a mathematical model of a
predator-prey system with pursuit and evasion. We demonstrate a new type of
propagating wave in this system. The mechanism of propagation of these waves
essentially depends on the ``taxis'', represented by nonlinear
``cross-diffusion'' terms in the mathematical formulation. We have shown that
the dependence of the velocity of wave propagation on the taxis has two
distinct forms, ``parabolic'' and ``linear''. Transition from one form to the
other correlates with changes in the shape of the wave profile. Dependence of
the propagation velocity on diffusion in this system differs from the
square-root dependence typical of reaction-diffusion waves. We demonstrate also
that, for systems with negative and positive taxis, for example, pursuit and
evasion, there typically exists a large region in the parameter space, where
the waves demonstrate quasisoliton interaction: colliding waves can penetrate
through each other, and waves can also reflect from impermeable boundaries.Comment: 15 pages, 18 figures, submitted to Physica
Envelope quasisolitons in dissipative systems with cross-diffusion
Copyright Β© 2011 American Physical SocietyJournal ArticleWe consider two-component nonlinear dissipative spatially extended systems of reaction-cross-diffusion type. Previously, such systems were shown to support "quasisoliton" pulses, which have a fixed stable structure but can reflect from boundaries and penetrate each other. Herein we demonstrate a different type of quasisolitons, with a phenomenology resembling that of the envelope solitons in the nonlinear SchrΓΆdinger equation: spatiotemporal oscillations with a smooth envelope, with the velocity of the oscillations different from the velocity of the envelope
Classification of wave regimes in excitable systems with linear cross diffusion
Copyright Β© 2014 American Physical SocietyWe consider principal properties of various wave regimes in two selected excitable systems with linear cross diffusion in one spatial dimension observed at different parameter values. This includes fixed-shape propagating waves, envelope waves, multienvelope waves, and intermediate regimes appearing as waves propagating at a fixed shape most of the time but undergoing restructuring from time to time. Depending on parameters, most of these regimes can be with and without the "quasisoliton" property of reflection of boundaries and penetration through each other. We also present some examples of the behavior of envelope quasisolitons in two spatial dimensions.Russian Foundation for Basic Research (RFBR
βΠΠ°Π΄ΠΎ, ΡΡΠΎΠ± ΠΊΠ°ΠΆΠ΄ΡΠΉ Π² Π‘ΠΎΡΠ·Π΅ ΡΠΈΡΠ°Π»β¦β: Π§ΠΈΡΠ°ΡΠ΅Π»Ρ ΠΊΠ°ΠΊ ΠΈΠ½ΡΡΠΈΡΡΡΠΈΡ ΡΠΎΠ²Π΅ΡΡΠΊΠΎΠΉ ΠΊΡΠ»ΡΡΡΡΡ
[Rev. of: Reading Russia. A History of Reading in Modern Russia. Volume 3. Edited by Damiano Rebecchini and Raffaella Vassena. Milano: UniversitΓ degli Studi di Milano, 2020]Β The present review focuses on the third volume of the collective study Reading Russia: A History of Reading in Modern Russia and aims at analyzing the methods of studying reading practices proposed in the aforementioned publication. The articles included in the peer-reviewed volume are studied in detail against the background of previously published scholarly literature on the history of reading, as well as in relation to archival and previously (un)published materials that have so escaped researchersβ attention. The broad historical and literary material shows that the Β«narrativesΒ» proposed in the reviewed volume do not present a full-fledged history of reading practices, but describe only individual disparate reading strategies of typologically different readers. The forms of institutionalization of reading in the USSR that were left out are sometimes much more important in the context of transformations in reading practices than the total collection of the Β«casesΒ» offered in the volume. At the same time, the case study review offers an opportunity to talk about βthe reader of the 20th centuryβ as a special institution of Soviet culture. This is why much of the review presents an attempt to find other principles and strategies of analysis on which the history of reading in the Β«small twentieth centuryΒ» can be based. The article offers a sociological portrait of the average reader, whose main features were formed during the Stalinist era and remained unchanged throughout the previous century. These features have existed in the same form for almost a quarter of the present century. The material that has been excluded from the present research can be divided into three groups: facts that characterize the Soviet state of affairs; information about the most important forms of institutionalized reading in the USSR-specific cultural environment; information concerning aesthetic and economic aspects of the book. A detailed commentary on each of these groups is intended to supplement and elaborate on the authors' concept. Along with the analysis of archival documents, we draw on materials from the funds of various public organizations and bodies, as well as periodicals, published memoirs, diaries and other materials available to us.Β DOI: 10.31168/2305-6754.2022.11.2.16[Π Π΅Ρ.: Reading Russia. A History of Reading in Modern Russia. Volume 3. Edited by Damiano Rebecchini and Raffaella Vassena. Milano: UniversitΓ degli Studi di Milano, 2020]Β ΠΡΠ΅Π΄Π»Π°Π³Π°Π΅ΠΌΡΠΉ ΠΎΠ±Π·ΠΎΡ ΠΏΠΎΡΠ²ΡΡΠ΅Π½ ΡΡΠ΅ΡΡΠ΅ΠΌΡ ΡΠΎΠΌΡ ΠΊΠΎΠ»Π»Π΅ΠΊΡΠΈΠ²Π½ΠΎΠ³ΠΎ ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΡ Β«Reading Russia: A History of Reading in Modern RussiaΒ» ΠΈ ΠΈΠΌΠ΅Π΅Ρ ΡΠ²ΠΎΠ΅ΠΉ Π·Π°Π΄Π°ΡΠ΅ΠΉ Π°Π½Π°Π»ΠΈΠ· ΠΏΡΠ΅Π΄Π»ΠΎΠΆΠ΅Π½Π½ΡΡ
Π² ΠΈΠ·Π΄Π°Π½ΠΈΠΈ ΠΌΠ΅ΡΠΎΠ΄ΠΎΠ² ΠΈΠ·ΡΡΠ΅Π½ΠΈΡ ΡΠΈΡΠ°ΡΠ΅Π»ΡΡΠΊΠΈΡ
ΠΏΡΠ°ΠΊΡΠΈΠΊ. ΠΠΎΡΠ΅Π΄ΡΠΈΠ΅ Π² ΡΠ΅ΡΠ΅Π½Π·ΠΈΡΡΠ΅ΠΌΡΠΉ ΡΠΎΠΌ ΡΡΠ°ΡΡΠΈ ΠΏΠΎΠ΄ΡΠΎΠ±Π½ΠΎ ΡΠ°ΡΡΠΌΠ°ΡΡΠΈΠ²Π°ΡΡΡΡ ΠΊΠ°ΠΊ Π½Π° ΡΠΎΠ½Π΅ ΡΠ°Π½Π΅Π΅ Π²ΡΡΠ΅Π΄ΡΠ΅ΠΉ Π½Π°ΡΡΠ½ΠΎΠΉ Π»ΠΈΡΠ΅ΡΠ°ΡΡΡΡ ΠΏΠΎ ΠΈΡΡΠΎΡΠΈΠΈ ΡΡΠ΅Π½ΠΈΡ, ΡΠ°ΠΊ ΠΈ Π² ΡΠ²ΡΠ·ΠΈ Ρ Π°ΡΡ
ΠΈΠ²Π½ΡΠΌΠΈ ΠΈ ΡΠ°Π½Π΅Π΅ (Π½Π΅)ΠΎΠΏΡΠ±Π»ΠΈΠΊΠΎΠ²Π°Π½Π½ΡΠΌΠΈ ΠΌΠ°ΡΠ΅ΡΠΈΠ°Π»Π°ΠΌΠΈ, ΠΊΠΎΡΠΎΡΡΠ΅ ΠΎΠΊΠ°Π·Π°Π»ΠΈΡΡ Π²Π½Π΅ ΠΏΠΎΠ»Ρ Π·ΡΠ΅Π½ΠΈΡ ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°ΡΠ΅Π»Π΅ΠΉ. ΠΠ° ΡΠΈΡΠΎΠΊΠΎΠΌ ΠΈΡΡΠΎΡΠΈΠΊΠΎ-Π»ΠΈΡΠ΅ΡΠ°ΡΡΡΠ½ΠΎΠΌ ΠΌΠ°ΡΠ΅ΡΠΈΠ°Π»Π΅ ΠΏΠΎΠΊΠ°Π·ΡΠ²Π°Π΅ΡΡΡ, ΡΡΠΎ ΠΏΡΠ΅Π΄Π»ΠΎΠΆΠ΅Π½Π½ΡΠ΅ Π² ΡΠ΅ΡΠ΅Π½Π·ΠΈΡΡΠ΅ΠΌΠΎΠΌ ΡΠΎΠΌΠ΅ Β«ΡΡΠΆΠ΅ΡΡΒ» Π½Π΅ ΠΎΠ±ΡΠ°Π·ΡΡΡ ΠΏΠΎΠ»Π½ΠΎΡΠ΅Π½Π½ΠΎΠΉ ΠΈΡΡΠΎΡΠΈΠΈ ΡΠΈΡΠ°ΡΠ΅Π»ΡΡΠΊΠΈΡ
ΠΏΡΠ°ΠΊΡΠΈΠΊ, Π½ΠΎ ΠΎΠΏΠΈΡΡΠ²Π°ΡΡ Π»ΠΈΡΡ ΡΠ°ΡΡΠ½ΡΠ΅ ΡΠ°Π·ΡΠΎΠ·Π½Π΅Π½Π½ΡΠ΅ ΡΡΡΠ°ΡΠ΅Π³ΠΈΠΈ ΡΡΠ΅Π½ΠΈΡ ΡΠΈΠΏΠΎΠ»ΠΎΠ³ΠΈΡΠ΅ΡΠΊΠΈ ΡΠ°Π·Π½ΡΡ
ΡΠΈΡΠ°ΡΠ΅Π»Π΅ΠΉ. ΠΡΡΠ°Π²Π»Π΅Π½Π½ΡΠ΅ Π±Π΅Π· Π²Π½ΠΈΠΌΠ°Π½ΠΈΡ ΡΠΎΡΠΌΡ ΠΈΠ½ΡΡΠΈΡΡΠ°Π»ΠΈΠ·Π°ΡΠΈΠΈ ΡΡΠ΅Π½ΠΈΡ Π² Π‘Π‘Π‘Π ΠΏΠΎΠ΄ΡΠ°Ρ ΠΎΠΊΠ°Π·ΡΠ²Π°ΡΡΡΡ ΠΊΡΠ΄Π° Π²Π΅ΡΠΎΠΌΠ΅Π΅ Π² ΠΊΠΎΠ½ΡΠ΅ΠΊΡΡΠ΅ ΡΡΠ°Π½ΡΡΠΎΡΠΌΠ°ΡΠΈΠΉ ΡΠΈΡΠ°ΡΠ΅Π»ΡΡΠΊΠΈΡ
ΠΏΡΠ°ΠΊΡΠΈΠΊ, ΡΠ΅ΠΌ Π²ΡΡ ΡΠΎΠ²ΠΎΠΊΡΠΏΠ½ΠΎΡΡΡ ΠΏΡΠ΅Π΄Π»ΠΎΠΆΠ΅Π½Π½ΡΡ
Π² ΡΠ±ΠΎΡΠ½ΠΈΠΊΠ΅ Β«ΠΊΠ΅ΠΉΡΠΎΠ²Β». ΠΠΌΠ΅ΡΡΠ΅ Ρ ΡΠ΅ΠΌ ΠΎΠ±Π·ΠΎΡ ΠΊΠΎΠ½ΠΊΡΠ΅ΡΠ½ΠΎΠ³ΠΎ ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΡ ΡΡΠ°Π½ΠΎΠ²ΠΈΡΡΡ ΠΏΠΎΠ²ΠΎΠ΄ΠΎΠΌ ΠΊ ΡΠ°Π·Π³ΠΎΠ²ΠΎΡΡ ΠΎ ΡΠΈΡΠ°ΡΠ΅Π»Π΅ ΠΏΡΠΎΡΠ»ΠΎΠ³ΠΎ ΡΡΠΎΠ»Π΅ΡΠΈΡ ΠΊΠ°ΠΊ ΠΎΠ± ΠΎΡΠΎΠ±ΠΎΠΉ ΠΈΠ½ΡΡΠΈΡΡΡΠΈΠΈ ΡΠΎΠ²Π΅ΡΡΠΊΠΎΠΉ ΠΊΡΠ»ΡΡΡΡΡ. ΠΠΌΠ΅Π½Π½ΠΎ ΠΏΠΎΡΡΠΎΠΌΡ Π±ΠΎΠ»ΡΡΠ°Ρ ΡΠ°ΡΡΡ ΠΎΠ±Π·ΠΎΡΠ° ΠΏΡΠ΅Π΄ΡΡΠ°Π²Π»ΡΠ΅Ρ ΡΠΎΠ±ΠΎΠΉ ΠΏΠΎΠΏΡΡΠΊΡ ΠΏΠΎΠΈΡΠΊΠ° ΠΈΠ½ΡΡ
ΠΏΡΠΈΠ½ΡΠΈΠΏΠΎΠ² ΠΈ ΡΡΡΠ°ΡΠ΅Π³ΠΈΠΉ Π°Π½Π°Π»ΠΈΠ·Π°, Π½Π° ΠΊΠΎΡΠΎΡΡΡ
ΠΌΠΎΠΆΠ΅Ρ Π±ΡΡΡ ΠΎΡΠ½ΠΎΠ²Π°Π½Π° ΠΈΡΡΠΎΡΠΈΡ ΡΡΠ΅Π½ΠΈΡ Π² Β«ΠΌΠ°Π»ΠΎΠΌ Π΄Π²Π°Π΄ΡΠ°ΡΠΎΠΌ Π²Π΅ΠΊΠ΅Β». Π ΡΡΠ°ΡΡΠ΅ ΠΏΡΠ΅Π΄Π»Π°Π³Π°Π΅ΡΡΡ ΡΠΎΡΠΈΠΎΠ»ΠΎΠ³ΠΈΡΠ΅ΡΠΊΠΈΠΉ ΠΏΠΎΡΡΡΠ΅Ρ ΡΡΡΠ΅Π΄Π½Π΅Π½Π½ΠΎΠ³ΠΎ ΡΠ΅ΡΠΈΠΏΠΈΠ΅Π½ΡΠ°, ΠΎΡΠ½ΠΎΠ²Π½ΡΠ΅ ΡΠ΅ΡΡΡ ΠΊΠΎΡΠΎΡΠΎΠ³ΠΎ ΡΡΠΎΡΠΌΠΈΡΠΎΠ²Π°Π»ΠΈΡΡ Π² ΡΠΏΠΎΡ
Ρ ΡΡΠ°Π»ΠΈΠ½ΠΈΠ·ΠΌΠ° ΠΈ ΠΎΡΡΠ°Π»ΠΈΡΡ Π½Π΅ΠΈΠ·ΠΌΠ΅Π½Π½ΡΠΌΠΈ Π½Π° ΠΏΡΠΎΡΡΠΆΠ΅Π½ΠΈΠΈ Π²ΡΠ΅Π³ΠΎ ΠΏΡΠΎΡΠ»ΠΎΠ³ΠΎ ΡΡΠΎΠ»Π΅ΡΠΈΡ ΠΈ Π² ΠΏΡΠ΅ΠΆΠ½Π΅ΠΌ Π²ΠΈΠ΄Π΅ ΠΏΡΠΎΠ΄ΠΎΠ»ΠΆΠ°ΡΡ ΡΡΡΠ΅ΡΡΠ²ΠΎΠ²Π°ΡΡ ΡΠΆΠ΅ ΠΏΠΎΡΡΠΈ ΡΠ΅ΡΠ²Π΅ΡΡΡ Π½ΡΠ½Π΅ΡΠ½Π΅Π³ΠΎ Π²Π΅ΠΊΠ°. ΠΠ΅ Π²ΠΎΡΠ΅Π΄ΡΠΈΠΉ Π² ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΠ΅ ΠΌΠ°ΡΠ΅ΡΠΈΠ°Π» ΡΡΠ»ΠΎΠ²Π½ΠΎ ΠΏΠΎΠ΄ΡΠ°Π·Π΄Π΅Π»ΡΠ΅ΡΡΡ Π½Π° ΡΡΠΈ Π³ΡΡΠΏΠΏΡ: ΡΠ°ΠΊΡΡ, Ρ
Π°ΡΠ°ΠΊΡΠ΅ΡΠΈΠ·ΡΡΡΠΈΠ΅ ΡΠΎΠ±ΡΡΠ²Π΅Π½Π½ΠΎ ΡΠΎΠ²Π΅ΡΡΠΊΠΎΠ΅ ΠΏΠΎΠ»ΠΎΠΆΠ΅Π½ΠΈΠ΅ Π΄Π΅Π»; ΡΠ²Π΅Π΄Π΅Π½ΠΈΡ ΠΎ Π²Π°ΠΆΠ½Π΅ΠΉΡΠΈΡ
Π΄Π»Ρ ΠΊΡΠ»ΡΡΡΡΠ½ΠΎΠΉ ΡΠΈΡΡΠ°ΡΠΈΠΈ Π‘Π‘Π‘Π ΡΠΎΡΠΌΠ°Ρ
ΠΈΠ½ΡΡΠΈΡΡΡΠΈΠΎΠ½Π°Π»ΠΈΠ·Π°ΡΠΈΠΈ ΡΡΠ΅Π½ΠΈΡ; Π΄Π°Π½Π½ΡΠ΅ ΠΎΠ± ΡΡΡΠ΅ΡΠΈΡΠ΅ΡΠΊΠΎΠΌ ΠΈ ΡΠΊΠΎΠ½ΠΎΠΌΠΈΡΠ΅ΡΠΊΠΎΠΌ Π°ΡΠΏΠ΅ΠΊΡΠ°Ρ
Π±ΡΡΠΎΠ²Π°Π½ΠΈΡ ΠΊΠ½ΠΈΠ³ΠΈ. ΠΠΎΠ΄ΡΠΎΠ±Π½ΡΠΉ ΠΊΠΎΠΌΠΌΠ΅Π½ΡΠ°ΡΠΈΠΉ ΠΊ ΠΊΠ°ΠΆΠ΄ΠΎΠΉ ΠΈΠ· ΡΡΠΈΡ
Π³ΡΡΠΏΠΏ ΠΏΡΠΈΠ·Π²Π°Π½ Π΄ΠΎΠΏΠΎΠ»Π½ΠΈΡΡ ΠΈ Π΄Π΅ΡΠ°Π»ΠΈΠ·ΠΈΡΠΎΠ²Π°ΡΡ ΠΏΡΠ΅Π΄Π»ΠΎΠΆΠ΅Π½Π½ΡΡ Π°Π²ΡΠΎΡΠ°ΠΌΠΈ ΠΊΠΎΠ½ΡΠ΅ΠΏΡΠΈΡ. ΠΠ°ΡΡΠ΄Ρ Ρ Π°Π½Π°Π»ΠΈΠ·ΠΎΠΌ Π°ΡΡ
ΠΈΠ²Π½ΡΡ
Π΄ΠΎΠΊΡΠΌΠ΅Π½ΡΠΎΠ², Π½Π°ΠΌΠΈ ΠΏΡΠΈΠ²Π»Π΅ΠΊΠ°ΡΡΡΡ ΠΌΠ°ΡΠ΅ΡΠΈΠ°Π»Ρ ΡΠΎΠ½Π΄ΠΎΠ² ΡΠ°Π·Π»ΠΈΡΠ½ΡΡ
ΠΎΠ±ΡΠ΅ΡΡΠ²Π΅Π½Π½ΡΡ
ΠΎΡΠ³Π°Π½ΠΈΠ·Π°ΡΠΈΠΉ ΠΈ ΠΎΡΠ³Π°Π½ΠΎΠ², Π° ΡΠ°ΠΊΠΆΠ΅ ΠΏΠ΅ΡΠΈΠΎΠ΄ΠΈΠΊΠ°, ΠΎΠΏΡΠ±Π»ΠΈΠΊΠΎΠ²Π°Π½Π½ΡΠ΅ Π²ΠΎΡΠΏΠΎΠΌΠΈΠ½Π°Π½ΠΈΡ, Π΄Π½Π΅Π²Π½ΠΈΠΊΠΎΠ²ΡΠ΅/ΠΌΠ΅ΠΌΡΠ°ΡΠ½ΡΠ΅ ΡΠ²ΠΈΠ΄Π΅ΡΠ΅Π»ΡΡΡΠ²Π° ΠΈ Π΄ΡΡΠ³ΠΈΠ΅ Π΄ΠΎΡΡΡΠΏΠ½ΡΠ΅ Π½Π°ΠΌ ΠΌΠ°ΡΠ΅ΡΠΈΠ°Π»Ρ.Β DOI: 10.31168/2305-6754.2022.11.2.1
Natural and chemotherapy-induced clonal evolution of tumors
Evolution and natural selection of tumoral clones in the process of transformation and the following carcinogenesis can be called natural clonal evolution. Its main driving factors are internal: genetic instability initiated by driver mutations and microenvironment, which enables selective pressure while forming the environment for cell transformation and their survival. We present our overview of contemporary research dealing with mechanisms of carcinogenesis in different localizations from precancerous pathologies to metastasis and relapse. It shows that natural clonal evolution establishes intratumoral heterogeneity and enables tumor progression. Tumors of monoclonal origin are of low-level intratumoral heterogeneity in the initial stages, and this increases with the size of the tumor. Tumors of polyclonal origin are of extremely high-level intratumoral heterogeneity in the initial stages and become more homogeneous when larger due to clonal expansion. In cases of chemotherapy-induced clonal evolution of a tumor, chemotherapy becomes the leading factor in treatment. The latest research shows that the impact of chemotherapy can radically increase the speed of clonal evolution and lead to new malignant and resistant clones that cause tumor metastasis. Another option of chemotherapy-induced clonal evolution is formation of a new dominant clone from a clone that was minor in the initial tumor and obtained free space due to elimination of sensitive clones by chemotherapy. As a result, in ~20% of cases, chemotherapy can stimulate metastasis and relapse of tumors due to clonal evolution. The conclusion of the overview formulates approaches to tumor treatment based on clonal evolution: in particular, precision therapy, prediction of metastasis stimulation in patients treated with chemotherapy, methods of genetic evaluation of chemotherapy efficiency and clonal-oriented treatment, and approaches to manipulating the clonal evolution of tumors are presented
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