BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//CERN//INDICO//EN
BEGIN:VEVENT
SUMMARY:A tribute to Marian Smoluchowski's legacy on colloid type matter a
ggregation\, and related issues
DTSTART;VALUE=DATE-TIME:20170904T123000Z
DTEND;VALUE=DATE-TIME:20170904T130000Z
DTSTAMP;VALUE=DATE-TIME:20220928T130021Z
UID:indico-contribution-29-162@zakopane.if.uj.edu.pl
DESCRIPTION:Speakers: Adam Gadomski (UTP University of Science and Technol
ogy Bydgoszcz\, Poland)\nIn 1916 Marian Smoluchowski proposed a case of co
nstant-kernel cluster cluster aggregation\, for which it is manageable to
find analitycally by employing scaling arguments\, a solution in terms of
the cluster size (k) distribution function\, n(k) [1\,2].\nBy applying thi
s scaling function it is then possible to get\, within the long times' lim
it\, the results for the mean cluster size {k} and the total number of the
clusters N\, both scalable in terms of time t with a single exponent\, g
[2].\nThe clustering arguments\, first introduced by Smoluchowski [1]\, ar
e easily applicable to statistical description of physical-metallurgical p
rocesses and ceramic-polycrystalline evolutions\, termed the normal grain
growth\, in which bigger clusters grow at the expense of their smaller nei
ghboring counterparts due to capillary conditions [3].\nThe normal grain g
rowth\, and its dynamics\, can be expressed in d-dimensional space (d - Eu
clidean dimension of the space). Upon identifying {k} from the Smoluchowsk
i description with {R}\, the mean cluster radius' size from the normal gra
in growth approach\, and by taking the "extreme" condition of k >> 0\, one
is able to embark on their equivalence by stating rigorously that g=1/(d+
1)\, since the asymptotic scaling rule for N (here: the number of grains)
goes via a simple logarithmic depiction as: ln[N]~-ln[g].\nThe crucial ass
umption\, however\, that assures the equivalence claimed\, appears to be f
ully feasible when rearranging the time domain by substituting t in a way
such that a new rescaled time variable T(t) is given by a definite integra
l in [0\,t] upon dT(t)=dt/f(t)\, with an adjustable function f\, coming fr
om the dispersive or long-tail\, or fractal kinetics' arguments [4].\nThe
arguments may at least qualitatively concern biomembranes dynamics\; they
can also contribute to nucleation-growth processes in (psychodynamic-clus
tering) living matter conditions [5-7].\n\n$ $\n\n[1] M. von Smoluchowski\
, Physikalische Zeitschrift **17**\, 585 (1916).\n\n[2] R. Jullien\, Croat
ica Chemica Acta **65**(2)\, pp. 215-235 (1992).\n\n[3] P.A. Mulheran\, J.
H. Harding\, Materials Science Forum **94-96**\, pp. 367-372\, 1992.\n\n[4
] A. Plonka\, Dispersive Kinetics\, Kluwer\, Dordrecht\, 2002.\n\n[5] A. G
adomski\, A. Gadomski\, European Physical Journal B **9**\, 569 - 571 (199
9).\n\n[6] A. Gadomski\, M. Ausloos\, T. Casey\, Nonlinear Dynamics in Psy
chology & Life Sciences **21**/2\, 129-141 (2017).\n\n[7] A. Gadomski\, P
hilosophical Magazine Letters **70**\, 335 (1994).\n\nhttps://zakopane.if.
uj.edu.pl/event/4/contributions/162/
LOCATION: 56
URL:https://zakopane.if.uj.edu.pl/event/4/contributions/162/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Thermodynamic activation energy for self diffusion and order-order
relaxation in intermetallic compounds: atomistic model and Monte Carlo si
mulations
DTSTART;VALUE=DATE-TIME:20170904T134000Z
DTEND;VALUE=DATE-TIME:20170904T140000Z
DTSTAMP;VALUE=DATE-TIME:20220928T130021Z
UID:indico-contribution-29-82@zakopane.if.uj.edu.pl
DESCRIPTION:Speakers: Rafal Abdank-Kozubski (M. Smoluchowski Institute of
Physics\, Jagiellonian University in Krakow)\nSelf-diffusion and the ‘or
der order’ relaxation process in intermetallic compounds is described in
terms of effective atomic jump frequencies and the current degree of chem
ical long-range order. It is demonstrated that the thermodynamic activatio
n energies of self-diffusion and the ‘order-order’ relaxation can be e
xpressed in terms of the activation energies of more elementary processes.
As the derived expressions differ from each other\, the values of the the
rmodynamic activation energies for self-diffusion and the ‘order order
’ relaxation can be different although both processes are controlled by
the same vacancy-mediated elementary atomic jumps.\nIn order to assess the
the validity of the derived formulae different B2-ordering binary systems
are simulated. The results of the computer experiments are in good agreem
ent with the tested formulae. It is shown that the relationship between th
e activation energies observed in triple defect B2-ordering binaries\, whe
re the value of the activation energy for order-order relaxations is subst
antially lower than that for self-diffusion\, does not hold in the case of
non-triple-defect binaries. Using the tested formulae\, the origin of the
effect is elucidated and attributed to the atomistic origin of the tenden
cy for triple-defect disordering.\n\n$ $\n\nP. Sowa\, A. Biborski\, M. Koz
łowski\, R. Kozubski\, I.V. Belova\, G.E. Murch: Atomistic origin of the
thermodynamic activation energy for self diffusion and order-order relaxat
ion in intermetallic compounds. Part I and Part II\, Philos.Mag.\, **97**\
, 1361-1374\, 1375-1397 (2017).\n\nhttps://zakopane.if.uj.edu.pl/event/4/c
ontributions/82/
LOCATION: 56
URL:https://zakopane.if.uj.edu.pl/event/4/contributions/82/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Stochastic advection-reaction-diffusion model for phytoplankton po
pulations in a 2D spatial domain
DTSTART;VALUE=DATE-TIME:20170904T132000Z
DTEND;VALUE=DATE-TIME:20170904T134000Z
DTSTAMP;VALUE=DATE-TIME:20220928T130021Z
UID:indico-contribution-29-37@zakopane.if.uj.edu.pl
DESCRIPTION:Speakers: Davide Valenti (Department of Physics and Chemistry\
, University of Palermo)\nPhytoplankton lies at the base of the food chain
of seas and oceans\, and it is responsible for about 80% of the total *ch
lorophyll a*. As a consequence\, phytoplankton determines the trophic stru
ctures of marine ecosystems\, while influencing the total abundance and th
e spatial distributions of marine biological species\, e.g. fish populatio
ns. Thus the study of spatio-temporal dynamics of phytoplankton population
s and the development of models which predict the trend of primary product
ion become of paramount importance to understand and forecast the dynamics
of biological species within marine ecosystems.\n Here it is presented a
two-dimensional advection-reaction-diffusion model to describe the dynami
cs of four phytoplankton populations in a real ecosystem located in the Ch
annel of Sicily (South Mediterranean Sea). Light intensity and nutrient co
ncentration represent the limiting factors for the phytoplankton growth. S
pecifically\, due to the characteristics of the marine ecosystem analyzed\
, i.e. a transect consisting of twelve marine stations between Cape Passer
o (Sicily) and Misurata (Libya) [1]\, the limiting nutrient component is p
hosphorus.\n Phytoplankton abundances are first obtained by solving numer
ically a system of deterministic partial differential equations and then c
onverted *chlorophyll a* concentrations [2]\, whose spatial distributions
are compared with those obtained from field data collected in the twelve m
arine stations [3]. Statistical checks based on the chi-square test indica
te a good agreement between theoretical and experimental distributions of
*chlorophyll a* concentration.\n Deterministic models however can not ful
ly describe the nonlinear dynamics of a real ecosystem continuously expose
d not only to deterministic but also to random perturbations coming from t
he environment. To take into account the random fluctuations of the enviro
nmental variables\, the deterministic model is modified by inserting in th
e equations Gaussian noise sources [4]. As confirmed by checks based on th
e chi-square test\, the distributions of *chlorophyll a* concentration obt
ained by the stochastic model fit the field data better than those calcula
ted by the deterministic model.\n It is worth noting that in this study r
eal values for physical and biological variables were used. Specifically\,
the analysis exploits hydrological and nutrients data acquired in situ\,
including intraspecific competition for limiting factors.\nThe study and t
he results discussed here indicate the effectiveness of this approach for
reproducing real spatial distributions of *chlorophyll a* concentration. M
oreover we note that the stochastic advection-reaction-diffusion model pre
sented in this work can be extended to different marine ecosystems and use
d as a global model to forecast eventual decreases in the abundance of pri
mary production and to prevent the consequent decline of fish species.\n\n
$ $\n\n[1] F. Placenti\, K. Schroeder\, A. Bonanno\, S. Zgozi\, M. Sprovie
ri\, M. Borghini \, P. Rumolo\, G. Cerrati\, S. Bonomo\, S. Genovese\, G.
Basilone\, D. A. Haddoud\, B. Patti\, A. El Turki\, M. Hamza\, S. Mazzola\
, Water masses and nutrient distribution in the Gulf of Syrte and between
Sicily and Libya\, J. Mar. Syst. 121-122\, 36-46 (2013).\n\n[2] C. Brunet\
, R. Casotti\, V. Vantrepotte\, F. Conversano\, Vertical variability and d
iel dynamics of picophytoplankton in the Strait of Sicily\, Mediterranean
Sea\, in summer\, Mar. Ecol. Prog. Ser. 346\, 15-26 (2007).\n\n[3] D. Vale
nti\, G. Denaro\, R. Ferreri\, S. Genovese\, S. Aronica\, S. Mazzola\, A.
Bonanno\, G. Basilone\, B. Spagnolo\, Sci. Rep.\, Spatio-temporal dynamics
of a planktonic system and chlorophyll distribution in a 2D spatial domai
n: matching model and data 7\, 220 (2017).\n\n[4] G. Denaro\, D. Valenti\,
B. Spagnolo\, G. Basilone\, S. Mazzola\, S. W. Zgozi\, S. \nAronica\, A.
Bonanno\, Dynamics of two pico-phytoplankton groups in Mediterranean Sea:
Analysis of the deep chlorophyll maximum by a stochastic advection-reactio
n-diffusion model\, PLoS ONE 8\, e66765 (2013).\n\nhttps://zakopane.if.uj.
edu.pl/event/4/contributions/37/
LOCATION: 56
URL:https://zakopane.if.uj.edu.pl/event/4/contributions/37/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Stationary diffusion among partially reactive sinks: from von Smol
uchowski to recent advances
DTSTART;VALUE=DATE-TIME:20170904T130000Z
DTEND;VALUE=DATE-TIME:20170904T132000Z
DTSTAMP;VALUE=DATE-TIME:20220928T130021Z
UID:indico-contribution-29-35@zakopane.if.uj.edu.pl
DESCRIPTION:Speakers: Denis Grebenkov (CNRS)\nIn 1917\, von Smoluchowski f
ounded the first mathematical theory of diffusion-limited reactions by com
puting the diffusive flux towards a perfect spherical sink. In spite of ma
ny advances over the past hundred years\, stationary diffusion in complex
media with numerous sinks of various shapes and reactivities remains poorl
y understood. After a brief overview\, we present a recently developed gen
eralized method of separation of variables (GMSV) to solve boundary value
problems for the Poisson equation in three-dimensional canonical domains (
e.g.\, parallelepipeds\, cylinders\, spheres\, spheroids\, ...\, \nand the
ir combinations). In particular\, we derive a semi-analytical representati
on of the Green function for an arbitrary configuration of non-overlapping
partially reactive spherical sinks. This is the key object to determine v
arious characteristics of stationary diffusion such as reaction rate\, esc
ape probability\, harmonic measure\, residence time\, and mean first passa
ge time\, to name but a few. Based on this solution\, we introduce and inv
estigate an effective reaction radius of individual sinks or their cluster
s that significantly generalizes the famous Smoluchowski formula by accoun
ting for diffusion interactions between sinks and their mutual screening.\
n\nhttps://zakopane.if.uj.edu.pl/event/4/contributions/35/
LOCATION: 56
URL:https://zakopane.if.uj.edu.pl/event/4/contributions/35/
END:VEVENT
END:VCALENDAR