ISCB2016 – 37 th annual conference of the International Society of Clinical Biostatistic s

\n\n

The ISCB 2016 conference will provide a scientific for um for international exchange of theory\, methods and applications of clin ical biostatistics among biostatisticians\, epidemiologists and other medi cal researchers.

\n END:VEVENT BEGIN:VEVENT UID:shc2crf0usod5luctm31d8v500@google.com DTSTAMP:20181211T062717Z CATEGORIES: CONTACT: DESCRIPTION:http://www.sbm.org.br/jointmeeting-italy DTSTART;VALUE=DATE:20160829 DTEND;VALUE=DATE:20160903 SEQUENCE:0 SUMMARY:!st Joint meeting Brazil-Italy in Mathematics URL:https://bio.mox.polimi.it/event/st-joint-meeting-brazil-italy-in-mathem atics/ X-ALT-DESC;FMTTYPE=text/html:\\n\\n\\nhttp://www.sb m.org.br/jointmeeting-italy

\n END:VEVENT BEGIN:VEVENT UID:mc9jcit7mhs63v4fqv2vjr3ogo@google.com DTSTAMP:20181211T062717Z CATEGORIES: CONTACT: DESCRIPTION: DTSTART;VALUE=DATE:20160908 DTEND;VALUE=DATE:20160910 SEQUENCE:0 SUMMARY:ESB-ITA Thematica Symposium “Frontier Biomechanical Challenges in C ardiovascular Physiopathology” URL:https://bio.mox.polimi.it/event/esb-ita-thematica-symposium-frontier-bi omechanical-challenges-in-cardiovascular-physiopathology/ END:VEVENT BEGIN:VEVENT UID:4e3lij13j5rrkp9sijr78c6cp4@google.com DTSTAMP:20181211T062717Z CATEGORIES: CONTACT: DESCRIPTION:http://www.bcamath.org/en/workshops/qbio2017 DTSTART;VALUE=DATE:20170221 DTEND;VALUE=DATE:20170223 SEQUENCE:0 SUMMARY:Third BCAM Workshop on Quantitative Biomedicine for Health and Dise ase URL:https://bio.mox.polimi.it/event/third-bcam-workshop-on-quantitative-bio medicine-for-health-and-disease/ X-ALT-DESC;FMTTYPE=text/html:\\n\\n\\nhttp://www.bc amath.org/en/workshops/qbio2017

\n END:VEVENT BEGIN:VEVENT UID:5scnmhq2fhu63il7etq2gbbvq0@google.com DTSTAMP:20181211T062717Z CATEGORIES: CONTACT: DESCRIPTION:http://dmf.unicatt.it/mathsfromthebody/ DTSTART;VALUE=DATE:20170529 DTEND;VALUE=DATE:20170601 SEQUENCE:0 SUMMARY:Maths from the body\, Brescia URL:https://bio.mox.polimi.it/event/maths-from-the-body-brescia/ X-ALT-DESC;FMTTYPE=text/html:\\n\\n\\nhttp://dmf.un icatt.it/mathsfromthebody/

\n END:VEVENT BEGIN:VEVENT UID:785u6su4jkc71s0vnm5s4cc7co@google.com DTSTAMP:20181211T062717Z CATEGORIES: CONTACT: DESCRIPTION:http://www.cism.it/courses/C1705/ DTSTART;VALUE=DATE:20170612 DTEND;VALUE=DATE:20170617 SEQUENCE:0 SUMMARY:23rd CISM-IUTAM International Summer School on “Growth and Remodeli ng in Soft Biological Tissue” URL:https://bio.mox.polimi.it/event/23rd-cism-iutam-international-summer-sc hool-on-growth-and-remodeling-in-soft-biological-tissue/ X-ALT-DESC;FMTTYPE=text/html:\\n\\n\\nhttp://www.ci sm.it/courses/C1705/

\n END:VEVENT BEGIN:VEVENT UID:b8fjqdens3a8aa5q6367ssvlao@google.com DTSTAMP:20181211T062717Z CATEGORIES: CONTACT: DESCRIPTION:http://congressi.iac.cnr.it/mathtech-mobi2017 DTSTART;VALUE=DATE:20170626 DTEND;VALUE=DATE:20170629 SEQUENCE:0 SUMMARY:INdAM workshop “Modeling and computational approaches to Biology an d Medicine” (MOBI 2017) URL:https://bio.mox.polimi.it/event/indam-workshop-modeling-and-computation al-approaches-to-biology-and-medicine-mobi-2017/ X-ALT-DESC;FMTTYPE=text/html:\\n\\n\\nhttp://congre ssi.iac.cnr.it/mathtech-mobi2017

\n END:VEVENT BEGIN:VEVENT UID:ho0g2n0ufe5ok5n984i7escc8o@google.com DTSTAMP:20181211T062717Z CATEGORIES: CONTACT: DESCRIPTION:http://595.euromech.org/ DTSTART;VALUE=DATE:20170829 DTEND;VALUE=DATE:20170901 SEQUENCE:0 SUMMARY:Colloquium 595 Biomechanics and computer assisted surgery meets med ical reality\, Lille URL:https://bio.mox.polimi.it/event/colloquium-595-biomechanics-and-compute r-assisted-surgery-meets-medical-reality-lille/ X-ALT-DESC;FMTTYPE=text/html:\\n\\n\\nhttp://595.eu romech.org/

\n END:VEVENT BEGIN:VEVENT UID:hcmjksri7bk5739aqlh1tkp21s@google.com DTSTAMP:20181211T062717Z CATEGORIES: CONTACT: DESCRIPTION:SEMINAR:\nAndrea Ghiglietti (Università degli Studi di Milano\, Dipartimento di Matematica “F. Enriques”)\nTitle:\nInteracting Generalize d Pòlya Urn Systems\nAbstract:\nWe consider a system of interacting Genera lized Pòlya Urns (GPUs) having irreducible mean replacement matrices. The interaction is modeled through the conditional probabilities to sample the colors from the urns\, that are defined as convex combinations of the urn proportions in the system. The weights of these combinations are gathered in the interacting matrix\, whose structure individuates subsystems of ur ns evolving with different behaviors: (i) the leading systems\, whose dyna mics is independent of the rest of the system (ii) the following systems\, whose dynamics “follows” the evolution of other urns of the system. We pr ovide a complete description of the asymptotic behavior of the system by p roving theoretical results on the sequence of the urn proportions. Specifi cally\, we establish the limiting proportions\, the convergence rates and the Central Limit Theorems in both the leading and the following systems. The main techniques adopted to prove these results consist in revisiting t he urn dynamics in the stochastic approximation framework and realizing a detailed analysis on the eigen-structure of the interacting matrix and the mean replacement matrices. Finally\, we present the expected results in t he case of diagonal mean replacement matrix and we discuss further extensi ons concerning a random and time dependent interacting matrix. DTSTART;TZID=Europe/Rome:20160201T133000 DTEND;TZID=Europe/Rome:20160201T150000 SEQUENCE:0 SUMMARY:Seminario BIOMOX : A. Ghiglietti (Università degli Studi di Milano) URL:https://bio.mox.polimi.it/event/seminario-biomox-a-ghiglietti-universit a-degli-studi-di-milano/ X-ALT-DESC;FMTTYPE=text/html:\\n\\n\\nSEMINAR:

\nAndrea Ghiglietti (Università degli Studi di Milano\, Dipartimento di M
atematica “F. Enriques”)

Title:

\nInteracting Generalized Pòl
ya Urn Systems

Abstract:

\nWe consider a system of interactin
g Generalized Pòlya Urns (GPUs) having irreducible mean replacement matric
es. The interaction is modeled through the conditional probabilities to sa
mple the colors from the urns\, that are defined as convex combinations of
the urn proportions in the system. The weights of these combinations are
gathered in the interacting matrix\, whose structure individuates subsyste
ms of urns evolving with different behaviors: (i) the leading systems\, wh
ose dynamics is independent of the rest of the system (ii) the following s
ystems\, whose dynamics “follows” the evolution of other urns of the syste
m. We provide a complete description of the asymptotic behavior of the sys
tem by proving theoretical results on the sequence of the urn proportions.
Specifically\, we establish the limiting proportions\, the convergence ra
tes and the Central Limit Theorems in both the leading and the following s
ystems. The main techniques adopted to prove these results consist in revi
siting the urn dynamics in the stochastic approximation framework and real
izing a detailed analysis on the eigen-structure of the interacting matrix
and the mean replacement matrices. Finally\, we present the expected resu
lts in the case of diagonal mean replacement matrix and we discuss further
extensions concerning a random and time dependent interacting matrix.

SEMINAR:

\nEmiliano Votta (DEIB\, Politecnico di Milano)

Title:

\nFin
ite element modeling of the mitral valve from clinical imaging: a tool to
support the optimization of surgical treatment

Abstract:

\nTh
e mitral valve is a particularly complex apparatus that separates the left
atrium from the left ventricle and guarantees unidirectional blood flow f
rom the former to the latter.

\nMitral valve patholgies have a high p
revalence and usually require surgical treatment\, repair being preferred
to substitution whenever possible. At the same time\, though\, mitral repa
ir can be complex and the corresponding clinicl outcomes are not always sa
tisfactory. For this reason the improvement of repair techniques and devic
es remains a focal clinical and research activity.

\nIn this process\
, numerical modelling has been used since the ’90s to gain insight into mi
tral valve biomechanics\, so to better understand mitral valve pathophysio
logy and support the development of more effective surgical approaches. In
the last decade in particular\, numerical models based on medical imaging
have been developed\, exploting the detailed anatomical information yield
ed by medical images. This evolution of the modelling approach has paved t
he way towards the use of numerical models as a support tool for the patie
nt-specific tailoring of mitral valve surgical repair.

\nIn the semin
ar\, the modeling activity carried out in this field by the Biomechanics R
esearch Group at DEIB\, Politecnico di Milano\, will be presented\; the po
tential of the developed modeling approach will be exemplified through rec
ent clinical applications\, and emphasis will focused on current and futur
e developments.

Contact:

\nchristian.vergara@polimi.it

SEMINAR:

\nGiuliana Indelicato (Dipartimento di Matematica\, Università degli Stud
i di Torino)

Title:

\nMathematical models of self-assembling
polypeptide nanoparticles

Abstract:

\nIn this talk I will dis
cuss a mathematical framework that allows to predict and classify the layo
ut of polypeptidic building blocks in synthetized nanoparticles. I will
focus on the *de-novo *system called SAPN (self-assembling polypeptide nan
oparticles) which self assembles from multiple copies of a polypeptidic bu
ilding block and has been designed to act as a repetitive antigen display
system in a novel generation of vaccines. Clinical trials on a vaccine aga
inst malaria based on this technology are due to start soon.

\nThe ch
aracterization of these particles by experimental methods only is not suff
icient to completely elucidate the morphology of the assembled structure.
Moreover\, the classical theory of Caspar and Klug for the

\narrangem
ents of protein clusters in viral capsids cannot be used because the SAPNs
particles exhibit more than the twelve pentagonal clusters allowed in suc
h classification. In this presentation I will show that graph-theoretical
methods can provide important insights into the geometry of such nanoparti
cles. I will study

\nand classify the topology of the protein network
s using tools from planar graph theory. Special attention will be devoted
to symmetric particles\,which can be fully described and classified.

Contact:

\ndavide.ambrosi@polimi.it

SEMINAR:

\nLev V. Beloussov (Lab of Developmental Biophysics\, Faculty of Biology\
, Moscow State University)

Title:

\nMorphomechanical approach
to embryonic development

Abstract:

\nMorphogenesis\, that is
\, creation of new forms and structures in development of organisms is the
main but still poorly understood component of ontogenesis. By the modern
criteria\, it belongs to the processes of self-organization\, which may be
simulated by two kinds of models: chemo-diffusional and those based upon
mechanical forces/stresses. Among the advantages of the latter ones are na
turally arisen feedbacks with 3-dimensional geometry\, permitting to repro
duce the complication of shapes without introducing each time ad hoc taken
interventions.

\nAs a first step\, a plausibility of mechanical mode
ls was supported by discovering the patterns of mechanical stresses (MS) i
n embryonic tissues\, regularly arranged in space/time of development. The
next step was to explore whether the already established MS can affect ne
wly generated mechanical forces within cells creating thus the feedback lo
ops able to drive forth morphogenesis. Experimental and model evidences on
the existence of such feedbacks will be presented.

\nRecently\, the
interest to morphomechanical approaches was greatly enhanced by discovery
of mechanosensitive genes participating in development of Drosophila\, fis
hes and amphibians. Taken together\, the data obtained during several last
decades strongly argue for a fundamental role of mechanically based feedb
acks in regulating development of organisms on different structural levels
.

Contact:

\npasquale.ciarletta@polimi.it

SEMINAR:

\nPaolo Decuzzi\, Ph.D (Laboratory of Nanotechnology for Precision Medici
ne Italian Institute of Technology\, Genova)

Title:

\nMULTIFU
NCTIONAL POLYMERIC NANOCONSTRUCTS: FROM IN-SILICO TO IN-VIVO

Abstr
act:

\nMultifunctional nanoconstructs are particle-based nano-scale s
ystems designed for the ‘smart’ delivery of therapeutic and imaging agents
. The Laboratory of Nanotechnology for Precision Medicine synthesizes poly
meric nanoconstructs with different sizes\, ranging from a few tens of nan
ometers to a few microns\; shapes\, including spherical\, cubical and disc
oidal\; surface properties\, with positive\, negative\, neutral coatings\;
and mechanical stiffness\, varying from that of cells to rigid\, inorgani
c materials\, such as iron oxide. These are the 4S parameters – size\, sha
pe\, surface\, stiffness – which can be precisely tuned in the synthesis p
rocess enabling disease- and patient-specific designs of multifunctional n
anoconstructs.

\nIn this lecture\, the application of these nanoconst
ructs to the detection and treatment of cancer lesions and cardiovascular
diseases\, such as thrombosis and atherosclerosis\, is discussed. The cont
ribution of the 4S parameters in modulating nanoconstruct sequestration by
the mononuclear phagocyte system\, organ specific accumulation\, and bloo
d longevity is also critically presented. These polymeric nanoconstructs c
an be loaded with a variety of therapeutic payloads – anti-cancer molecule
s (docetaxel\, paclitaxel\, doxorubicin)\, anti-inflammatory molecules (cu
rcumin\, diclofenac\, celecoxib) and small biologicals (peptides\, siRNAs\
, miRNAs)\; and imaging agents – optical probes\; Gd and iron oxide nanopa
rticles for MR imaging\; and radio-isotopes for Nuclear Imaging.

\nFu
rthermore\, the lecture presents on the fabrication and testing of microfl
uidic chips for analyzing the vascular and extravascular mass transport\,
over multiple spatial and temporal scales\, of molecules\, nanoparticles a
nd cells. These microfluidic-chips can help in elucidating biophysical mec
hanisms modulating progression and regression of various diseases\, such a
s cancer\, cardiovascular and neurodegenerative\, as well as in developing
organ-on-a-chip systems for rapid drug and nanomedicine screenings and ti
ssue regeneration.

Contact:

\npaolo.zunino@polimi.it

SEMINAR:

\nMikel Landajuela\, MOX\, Dipartimento di Matematica\, Politecnico di Mi
lano

Title:

\nCoupling schemes and unfitted mesh methods for
fluid-structure interaction

Abstract:

\nThis work is devoted
to the development and analysis of efficient numerical algorithms for the
simulation of mechanical systems involving the interaction of a deformable
thin-walled structure with an internal or surrounding incompressible flui
d flow.

\nIn the first part\, we introduce two new classes of explici
t coupling schemes using fitted fluid and solid meshes. The methods propos
ed combine a certain (parameter free) Robin-consistency in the system with
(i) a projection-based time-marching in the fluid or (ii) second-order ti
me-stepping in both the fluid and the solid. The stability properties of t
he methods are analyzed within representative linear settings. This part i
ncludes also a comprehensive numerical study in which state-of-the-art cou
pling schemes (including some of the methods proposed herein) are compared
and validated against the results of an experimental benchmark.

\nIn
the second part\, we consider unfitted mesh formulations. These approache
s are more versatile at simulating problems with large interface deflectio
ns and/or topological changes. The spatial discretization in this case is
based on variants of Nitsche’s method with cut elements. Robustness with r
espect to arbitrary interface intersections is guaranteed through suitable
stabilization. For a fictitious domain setting using overlapping meshes\,
we present two new classes of splitting schemes which exploit the aforeme
ntioned interface

\nRobin-consistency in the unfitted frame- work. Th
e semi-implicit or explicit nature of the splitting in time is dictated by
the order in which the spatial and time discretizations are performed. In
the case of the coupling with immersed structures\, weak and strong disco
ntinuities across the interface are allowed for the velocity and pressure\
, respectively. Stability and error estimates are provided\, using energy
arguments within a linear setting. A series of numerical tests\, involving
static and moving interfaces\, illustrates the performance of the differe
nt methods proposed.

Contact:

\nchristina.vergara@polimi.it\n
END:VEVENT
BEGIN:VEVENT
UID:pl36k9t4pajfbtqahu6rc0pd1c@google.com
DTSTAMP:20181211T062717Z
CATEGORIES:
CONTACT:
DESCRIPTION:SEMINAR:\nNicholas Tarabelloni\, Lab MOX – Dipartimento di Mate
matica\, Politecnico di Milano\nTitle:\nStatistical assessment and calibra
tion of numerical models with functional response\nAbstract:\nThanks to th
e rise in computational resources that are increasingly becoming available
\, numerical models of all fields are experiencing a growth of complexity
and realism. This is especially the case for mathematical models dealing w
ith biomedical phenomena\, whose goal is to describe the behaviour of phys
iological processes of human beings. To this aim\, it is now possible to c
ombine them with diverse and complex data coming from real experiments\, h
ospital collections and surveys in order to enhance the modelling. This is
of extreme importance for the development of a personalised medicine prac
tice able to instruct clinicians and recommend treatments for targeted pat
ients.\nWithin this context\, we will focus on the problem of assessing th
e quality and calibrating numerical models producing functional observatio
ns\, i.e. quantity of interest that can naturally be thought as continuous
ly depending on some variable (e.g. time). To this aim\, we will present a
general statistical framework based on depth measures and spatial quantil
es for multi-dimensional data which is able to naturally and non-parametri
cally exploit a whole collection of real measurements\, to drive the calib
ration towards multiple possible goals and finally to enhance the agreemen
t between simulated data and real data. We will show an application to the
calibration of ODE and PDE based numerical models for the simulation of p
hysiological ECG traces to a dataset of hospital recordings.\nContact:\nch
ristian.vergara@polimi.it
DTSTART;TZID=Europe/Rome:20160630T093000
DTEND;TZID=Europe/Rome:20160630T110000
LOCATION:Aula Saleri VI Piano Dipartimento di Matematica\, Politecnico di M
ilano
SEQUENCE:0
SUMMARY:Seminario biomox Tarabelloni
URL:https://bio.mox.polimi.it/event/seminario-biomox-tarabelloni/
X-ALT-DESC;FMTTYPE=text/html:\\n\\n\\n

SEMINAR:

\nNicholas Tarabelloni\, Lab MOX – Dipartimento di Matematica\, Politecni
co di Milano

Title:

\nStatistical assessment and calibration
of numerical models with functional response

Abstract:

\nThan
ks to the rise in computational resources that are increasingly becoming a
vailable\, numerical models of all fields are experiencing a growth of com
plexity and realism. This is especially the case for mathematical models d
ealing with biomedical phenomena\, whose goal is to describe the behaviour
of physiological processes of human beings. To this aim\, it is now possi
ble to combine them with diverse and complex data coming from real experim
ents\, hospital collections and surveys in order to enhance the modelling.
This is of extreme importance for the development of a personalised medic
ine practice able to instruct clinicians and recommend treatments for targ
eted patients.

\nWithin this context\, we will focus on the problem o
f assessing the quality and calibrating numerical models producing functio
nal observations\, i.e. quantity of interest that can naturally be thought
as continuously depending on some variable (e.g. time). To this aim\, we
will present a general statistical framework based on depth measures and s
patial quantiles for multi-dimensional data which is able to naturally and
non-parametrically exploit a whole collection of real measurements\, to d
rive the calibration towards multiple possible goals and finally to enhanc
e the agreement between simulated data and real data. We will show an appl
ication to the calibration of ODE and PDE based numerical models for the s
imulation of physiological ECG traces to a dataset of hospital recordings.

Contact:

\nchristian.vergara@polimi.it

SEMINAR:

\nS. pagani\, MOX\, Dipartimento di Matematica\, Politecnico di Milano

Title:

\nA reduced-order strategy for efficient state/parameter
identification in cardiac electrophysiology

Abstract:

\nA re
duced basis (RB) ensemble Kalman Filter is proposed for the efficient solu
tion of Bayesian inverse problems\, namely state/parameter identification
and uncertainty quantification\, arising from cardiac electrophysiology. I
n particular\, starting from noisy boundary data\, we aim at identifying t
he position and the form of ischemic regions described through suitable pa
rametrized quantities or fields.

\nIn this context\, the forward prob
lem is typically modeled by a system of nonlinear unsteady PDEs\, e.g. the
monodomain or the bidomain equations for the propagation of the electric
potential in the cardiac muscle. The ensemble Kalman Filter (like other Ba
yesian filtering techniques) requires a huge amount of queries to the forw
ard problem\, thus entailing an often prohibitive computational cost. To s
peed up the solution of the inverse problem\, we exploit a reduced basis m
ethod to approximate the solution of the forward problem. In particular\,
we adopt a RB method relying on (i) proper orthogonal decomposition for th
e construction of RB spaces\, (ii) clustering techniques for the sake of s
election of local RB spaces and (iii) suitable hyper-reduction techniques\
, such as the discrete empirical interpolation method\, for the evaluation
of nonlinear terms.

\nA relevant question\, arising when a reduced-o
rder model (like the one built with the RB method) is exploited to solve i
nverse problems\, is related to the propagation along the filtering proces
s of reduction errors (i.e. the error between the full-order and the reduc
ed-order model). Indeed\, it is crucial to be able to quantify these latte
r in order to obtain an accurate solution to the inverse problem. As a con
sequence\, we consider a reduction error model based on kriging interpolat
ion in order to gauge the effect of the state reduction on the whole inver
sion procedure.

\nAs a proof of concept\, we present some numerical r
esults exploiting the proposed procedure when a monodomain model is used f
or the description of the electrical potential in presence of ischemic are
as\, described through some unknown or uncertain parameters/fields.

\nchristian.vergara@polimi.it\n END:VEVENT BEGIN:VEVENT UID:8g7hfm4clebhrbsej0l3a8g1ac@google.com DTSTAMP:20181211T062717Z CATEGORIES: CONTACT: DESCRIPTION:SEMINAR:\nBruno Guerciotti\, MOX – Dipartimento di Matematica\, Politecnico di Milano\nTitle:\nComputational study of the risk of resteno sis in coronary bypasses\nAbstract:\nCoronary artery disease\, which is on e of the leading causes of death in the world\, is caused by the build-up of atherosclerotic plaques in the vessel walls. The result is a reduction of oxygen supply to the heart\, which increases the risk of myocardial inf arction\, stroke and unstable angina. For high-risk patients\, coronary ar tery bypass graft (CABG) is the preferred treatment. In particular\, the g old standard procedure for the surgical treatment of the left anterior des cending (LAD) coronary artery disease is the left internal mammary\nartery (LIMA) bypass. However\, despite its excellent patency rates\, LIMA\nbypa ss may fail due to restenosis. Specifically\, the long-term patency of LIM A is thought to be related to the degree of stenosis in the native vessel. \nIn this context\, we present a computational study of the fluid-dynamics in patient-specific geometries with the aim of investigating a possible r elationship between coronary stenosis and LIMA graft failure. Firstly\, we propose a strategy to prescribe realistic boundary conditions in absence of measured data\, based on an extension of the well–known Murray’s law to provide the flow division at bifurcations in case of stenotic vessels and non-Newtonian blood rheology. With the aim of investigating the actual in fluence of non-Newtonian blood rheology on the hemodynamics of 3D patient- specific stenotic vessels\, we also show some results regarding the compar ison between Newtonian and non-Newtonian rheology. Then\, we show the resu lts regarding numerical simulations in patients treated with grafts in whi ch the degree of coronary stenosis is virtually varied\, in order to compa re the fluid-dynamics in terms of hemodynamic indices potentially involved in restenosis development. Finally\, we present some preliminary results concerning fluid-structure interaction simulations in CABGs with the aim o f better understanding the influence of the bypass mechanical properties o n the risk of graft failure.\nContact:\nchristian.vergara@polimi.it DTSTART;TZID=Europe/Rome:20160928T123000 DTEND;TZID=Europe/Rome:20160928T133000 LOCATION:Aula Saleri VI Piano Dipartimento di Matematica\, Politecnico di M ilano SEQUENCE:0 SUMMARY:Seminario biomox Guerciotti URL:https://bio.mox.polimi.it/event/seminario-biomox-guerciotti/ X-ALT-DESC;FMTTYPE=text/html:\\n\\n\\n

SEMINAR:

\nBruno Guerciotti\, MOX – Dipartimento di Matematica\, Politecnico di Mi
lano

Title:

\nComputational study of the risk of restenosis i
n coronary bypasses

Abstract:

\nCoronary artery disease\, whi
ch is one of the leading causes of death in the world\, is caused by the b
uild-up of atherosclerotic plaques in the vessel walls. The result is a re
duction of oxygen supply to the heart\, which increases the risk of myocar
dial infarction\, stroke and unstable angina. For high-risk patients\, cor
onary artery bypass graft (CABG) is the preferred treatment. In particular
\, the gold standard procedure for the surgical treatment of the left ante
rior descending (LAD) coronary artery disease is the left internal mammary

\nartery (LIMA) bypass. However\, despite its excellent patency rate
s\, LIMA

\nbypass may fail due to restenosis. Specifically\, the long
-term patency of LIMA is thought to be related to the degree of stenosis i
n the native vessel.

\nIn this context\, we present a computational s
tudy of the fluid-dynamics in patient-specific geometries with the aim of
investigating a possible relationship between coronary stenosis and LIMA g
raft failure. Firstly\, we propose a strategy to prescribe realistic bound
ary conditions in absence of measured data\, based on an extension of the
well–known Murray’s law to provide the flow division at bifurcations in ca
se of stenotic vessels and non-Newtonian blood rheology. With the aim of i
nvestigating the actual influence of non-Newtonian blood rheology on the h
emodynamics of 3D patient-specific stenotic vessels\, we also show some re
sults regarding the comparison between Newtonian and non-Newtonian rheolog
y. Then\, we show the results regarding numerical simulations in patients
treated with grafts in which the degree of coronary stenosis is virtually
varied\, in order to compare the fluid-dynamics in terms of hemodynamic in
dices potentially involved in restenosis development. Finally\, we present
some preliminary results concerning fluid-structure interaction simulatio
ns in CABGs with the aim of better understanding the influence of the bypa
ss mechanical properties on the risk of graft failure.

Contact:

\nchristian.vergara@polimi.it

SEMINAR:

\nEnrico Facca\, Franco Cardin\, Mario Putti (Dipartimento di Matematica\
, Università di Padova)

Title:

\nBiologically inspired formul
ation of optimal transportation problems. An unexpected branching source\n

Abstract:

\nWe have recently developed an approach\, based on
an extension of a model proposed by Tero et al (2007) for the simulation o
f the dynamics of a slime mold (Physarium Polycephalum). We conjecture th
at this model is an original formulation of the PDE-based OT problem. This
new formulation assumes that the potential and the diffusion coefficient
(the latter yielding the transportation plan) are time dependent. The clas
sical constraint on the norm of the gradient is then replaced by an ODE de
scribing transient dynamics of the diffusion coefficient.

\nAnalytica
l results in the case of the Monge-Kantorovich problem\, although yet larg
ely incomplete\, suggest that indeed the conjecture is true. This is suppo
rted by several numerical experiments showing that at large times the solu
tion to this problem is equivalent to the solution of the classical Monge-
Kantorovich PDE based OT. One of the most important advantages of the prop
osed formulation is that its numerical solution is very efficient and well
-defined using simple numerical approaches. Moreover\, this dynamical exte
nsion allows the reconstruction of the time-history of the process\, thus
enlarging the applicability of the OT model to wider sets of processes. Th
e proposed model can also be easily adapted to branched and congested tran
sport problems. Preliminary numerical simulations show that the proposed f
ormulation is efficient in finding solutions also of congested transport a
nd branched transport problems.

\nWhile the interpretation via $p$-La
placians allows a straight forward interpretation of the new formulation i
n the simulation of congested transport\, only numerical evidence is curre
ntly available for applications to branched transport problems. Although
obvious limitations are present in the numerical solution of highly discon
tinuous problems\, we present some experimental convergence results showin
g robustness of the scheme for sufficiently regular solutions. Finally\, w
e will present models and related numerical results of diverse applicatio
ns of this formulation ranging from slime-mold dynamics to geomorphologica
l applications\, and discuss current and future progress.

Contact:

\nchristian.vergara@polimi.it

SEMINAR:

\nRiccardo Gottardi\, Center for Cellular and Molecular Engineering\, Uni
versity of Pittsburgh\, PA\, USA

Title:

\n3D microphysiologic
al systems: from modeling\, to drug discovery\, developmental biology\, an
d space research

Abstract:

\nA growing research in recent yea
rs focused on the development of next generation bioreactors capable of ge
nerating engineered constructs that mimic at least some of the physiologic
al functions of native organ systems. Such microphysiological systems rely
on the combination of microfluidic and tissue engineering to generate a h
igh number of identical 3D organoid models that can be used for drug and t
oxicological screening.

\nMoreover\, the ultimate aim is to be able t
o connect multiple tissues within an organ system and from there multiple
organ systems among themselves to better recapitulate the complexity and i
nterconnection of human physiology\, going from organ-on-a-chip to humans-
on-a-chip. The effective development of these devices requires a solid und
erstanding of their interconnected fluidics to predict the transport of nu
trients and waste through the constructs and improve the design accordingl
y. In this lecture\, the focus will be on a specific model of bioreactor d
eveloped at the Center for Cellular and Molecular Engineering (CCME)\, wit
h multiple input/outputs\, aimed at generating osteochondral constructs\,
i.e.\, a biphasic construct in which one side is cartilaginous in nature\,
while the other is osseous. Some of the challenges at the level of comput
ational modelling of the system will be described\, such as addressing the
multi-physics nature of the problem that combines free flow in cha!

\n nnels with hindered flow in porous media\, and coupling of fluid dynami
cs with advection-diffusion-reaction equations that model the transport of
biomolecules throughout the system and their interaction with living cons
tructs. The same design and modelling approach is applicable to multi-cham
ber\, interconnected system. In particular\, it may be applied to human-on
-chip devices. To this end\, a lumped parameter approach to predict the be
havior of multi-unit bioreactor systems with modest computational effort\,
will also be described. Furthermore\, the lecture will present a comparis
on of the modeling outcomes with the experimental results and will introdu
ce some of the opportunities opened by the possibility of using microphysi
ological systems to understand human physiology in challenging environment
s\, such as microgravity on board the International Space Station\, which
is the object of a recent grant obtained by CCME. Finally\, the lecture wi
ll outline some open problems where a !

\n modelling and computationa
l approach can help guide the experi!

\n mental development of microp
hysiological systems\, such as understanding the processes of limb morphog
enesis\, digit patterning\, and segmentation\, and their translation to a
regenerative approach.

SEMINAR:

\nLaura Sangalli (MOX)

Title:

\nPDE regularized principal co
mponent analysis on bidimensional manifolds\, with applications to neuroim
aging data

Abstract:

\nMotivated by the analysis of high-dime
nsional neuroimaging signals over the cerebral cortex\, we introduce a pri
ncipal component analysis technique that can be used for exploring the va
riability and performing dimensional reduction of signals observed over tw
o-dimensional manifolds. The proposed method is based on a PDE regularizat
ion approach\, involving the Laplace-Beltrami operator associated to the m
anifold domain. The model introduced can be applied to data observed over
any two-dimensional manifold topology\, and can naturally handle missing d
ata and signals evaluated in different grids of points. The proposed metho
d is applied to the analysis of resting state functional magnetic resonanc
e imaging data from the Human Connectome Project.

Contact:

\n
christian.vergara@polimi.it

SEMINAR:

\nJ. F. Rodriguez\, Chemistry\, Materials\, and Chemical Engineering Depa
rtment “Giulio Natta”\, Politecnico di Milano

Title:

\nModeli
ng Inelastic Effects in Reconstituted Crosslinked F-Actin Networks

Abstract:

\nThe interplay between the conventional cross-linked acti
n filaments by means of actin-binding proteins\, and physical bundling\, b
y means of spatial organization of nucleating factors can be an alternativ
e to understand several inelastic effects that take place in the cytoskele
ton. In this regard\, in vitro actin networks without active molecular mot
ors have been considered to be in thermodynamic equilibrium[1]. However\,
recent experiments performed by Schmoller et

\nal. [5] in artificiall
y reconstructed crosslinked actin networks have shown this networks to be
non-equilibrium networks. In their experiments they have observed that\, t
he internal stress trapped during network formation gives this material a
unique behavior. Differently to most soft materials\, such as rubber and l
iving soft tissues\, where nonlinear deformations irreversibly alter the m
echanical properties of the material by causing a pronounced softening whe
n cyclically deformed\, reconstituted crosslinked actin networks show soft
ening and hardening effects

\nwhen the network is subject to cyclic s
hear strain. As a continuation of a previous work [2]\, here we propose a
constitutive model within the framework of continuum mechanics for the ine
lastic stress-strain behavior of reconstituted crosslinked actin networks.
The network will be described using an homogenized framework based on the
eight chain model [3]. A dynamic model for the crosslinks is introduced i
n order to account for the inelastic response

\nof the network. In th
is regard\, we assume that crosslinks can be disrupted in either a reversi
ble or irreversible manner. Reversible disruption of a crosslink is modele
d as a two state process [4] in which the transition rates are modulated b
y the out of equilibrium forces. On the contrary\, irreversible crosslink
disruption will be modeled as a Bell-like bond rupture. These effects are
introduced in the model by considering the bundle contour length\, Lc as a
n

\nstochastic variable dependent on the reversible and irreversible
dynamics of the crosslink.

Contact:

\nchristian.vergara@polim
i.it

SEMINAR:

\nDaniele Bissacco\, Scuola di Specializzazione in Chirurgia Vascolare\,
Università degli Studi di Milano

Title:

\nAneurisma dell’aor
ta addominale: dalla clinica alla bioingegneria. Il punto di vista medico<
/p>\n

Abstract:

\nL’Aneurisma dell’Aorta Addominale (AAA) è definit
o come una dilatazione patologica del vaso arterioso che assicura l’apport
o sanguigno al distretto addominale e degli arti inferiori. Circa il 7% de
lla popolazione sopra i 70 anni è affetta da AAA\, che in caso di rottura\
, possiede una mortalità superiore all’80%. L’eziopatogenesi e la storia n
aturale non sono ancora state chiarite\, sebbene basi emodinamiche\, bioch
imiche e ambientali siano coinvolte nella formazione e progressione della
sacca aneurismatica. La terapia endovascolare (EVAR)\, mediante l’utilizzo
di endoprotesi posizionate e rilasciate da accessi femorali è al momento
la soluzione gravata da un minor tasso di complicanze immediate rispetto a
lla terapia chirurgica open\, sebbene una attenta sorveglianza dell’impian
to protesico debba essere proseguita anche anni dopo l’intervento.

\n
Il seminario si propone di descrivere le basi cliniche\, le cause e i fatt
ori di rischio per la comparsa di AAA\, le opzioni terapeutiche utilizzate
e le complicanze correlate all’intervento. Particolare interesse verrà da
to ai campi di ricerca clinica e bioingegneristica futuri\, per stimolare
la cooperazione tra figure professionali sempre più reciprocamente utili n
el capo della ricerca medica.

Contact:

\nchristian.vergara@po
limi.it