# Department Seminar Series

### Science Building, Wilfrid Laurier University

The Department of Physics & Computer Science at Wilfrid Laurier University presents a monthly seminar series. The talks are held every second Tuesday of the month at 4:00 p.m. and are aimed at fostering thought-provoking interactions among students, staff and faculty from WLU and other institutions. Everyone is welcome!

For further information about the seminars or if you are interested in giving a talk, please contact Ilias Kotsireas (ikotsireas@wlu.ca) or Marek Wartak (mwartak@wlu.ca).

# Asteroids That Share a Planet's Orbit: the First Retrograde Co-orbital Asteroid

#### Dr. Paul Weigert - Physics and Astronomy, UWO

There are about 6000 asteroids which share Jupiter's orbit around the Sun. Called the 'Trojan asteroids', they co-exist easily with this giant planet because they travel in the same direction as it, and remain roughly 60 degrees ahead of or behind it in its orbit. An as-yet-unnamed asteroid designated 2015 BZ509 is traveling in the opposite direction to Jupiter (and to all the planets in fact, as well as 99.99% of the other asteroids in our Solar System: a state referred to as 'retrograde' motion) but is also safely sharing Jupiter's orbital space. Asteroid 2015 BZ509 is trapped in a state dynamically analogous to that of the prograde Trojans. We'll discuss the motion of this curious asteroid - listed #47 in Discover magazine's Top 100 science stories of 2017 - and the other co-orbital bodies of our Solar System, examples which are now known for all planets except Mercury and Saturn.

# Group-Authentication Schemes for 5G-based V2X Communications

#### Prof. Sanaa Taha, Cairo University, Egypt

In vehicle to everything (V2X) communications, 5G cellular network is expected to dramatically decrease network latency overheads, to the extent of 1msec latency. V2X applications, such as automated driving and overtake, cooperative collision avoidance, and see through cars, have been proliferated recently with the introduction of 5G network slicing, virtualization and Software-Defined Networking (SDN). However achieving such low latency with such high mobility vehicular networks is a challenge, especially, with the V2X security requirements, such as authenticating a vehicle inside its PLMN as well as when roaming to another PLMN. One promising solution is achieving group authentication for dynamic vehicular clustering. Besides achieving low authentication overhead, dynamic vehicle clustering achieves vehicle anonymity when share a group key for the vehicles. Additionally vehicle clustering increases spectrum and channel capacity utilization and scheduling,network longevity, and data aggregation, while decreases congestion, packet loss, and latency, by solving the broadcast storm problem . Also, grouping the vehicles into clusters, with a cluster head, decreases the need of deploying many RSUs on the road, while having the advantage of dealing with the network as infrastructure-based one. In this talk, We first introduce the 5G technology and its attached concepts, include SDN and NFV. Then, we explain a proposes four integrated authentication schemes that can be used to achieve 5G-based v2x group authentication, namely: initial, service, handover, and group authentications. We rely on transmitting a service ticket and a vehicle's pseudo identity to the authenticated vehicle to be used in other authentication schemes. Unlike previous authentication schemes, our proposed schemes base on symmetric key cryptography using group and shared keys between the authenticated vehicle and other entities in 5G network. The security analysis shows that our proposed schemes thwart authentication inside and outside attacks, such as MITM, Replay, and DoS attacks. Also, the proposed group authentication and handover authentication achieves up to 50% and 99% less computation overhead, comparing with previous schemes.

# Real Physics from Virtual Quarks

#### Dr. Dandy Lewis - York University

The subatomic world is strongly influenced by the presence of virtual particles. Fortunately, the concept of virtual particles is not as complicated as one might think. This talk will describe the intuitive understanding of virtual particles, and will explain in simple but accurate language how calculations are performed. Unlike most virtual particles, virtual quarks require the use of high-performance computing. Theoretical calculations involving virtual quarks are essential for large international experiments that search for physics beyond the standard model, and this talk will focus on two top-priority examples for 2018: virtual quarks affecting the muon's magnetic moment (being measured at Fermilab) and the QCD coupling (required for studies of the Higgs boson at CERN).

# Usage of (Multiple) Code Invariant to Find the Symmetric W(23, 16)

#### Dr. Giora Dula - Netanya College, Israel

Hadamard and weighing matrices W(n;w) have applications in communications, chemistry and quantum computation. Given two matrices A;B, they are Hadamard equivalent if B is obtained from A by permuting rows or columns or by multiplying rows or columns by -1. Given (n;w), the number of Hadamard equivalence classes of W(n;w) in an open problem. In particular the question if this number is different than zero (existence) is an open question. Another open problem is given (n;w) to find W(n;w) which is (anti) symmetric.

# Gravitation, Dark Matter and Energy and Black Holes

#### John W. Moffat - Perimeter Institute, Waterloo

Moffat will review the present state of gravitation theory, with an emphasis on alternative theories of gravitation. Moffat will also discuss his own modified gravity (MOG) theory which will explain galaxy and cluster dynamics without detectable dark matter. Other topics which will be covered include, standard model of cosmology (Lambda CDM), Einstein’s prediction of mysterious black holes and gravitational waves, as well as the dramatic possibility of detecting the event horizon and the sillouette shadow cast by the supermassive black hole at the center of our Milky Way.

# Smartphones Enable Smart Cities

#### Dr. Petros Spachos - School of Engineering - Director, GryPHone Lab - University of Guelph

The expanding capabilities and growing number of smartphone devices are producing a new computing infrastructure integrating smart phones, users and sensors. User expect their phones to locate their social network friends; turn on the lights of the living room; report the temperature in their car; provide instant access to video and music and communicate with all the other wireless enable devices in the area - all in addition to placing phone calls and sending text messages. I will give an overview of the research activities at GryPHone Lab, the open-access smartphone testbed at the University of Guelph. GryPHoneLab is designed to enable mobile systems research that cannot be done in any other way.

# Mathematical Tracing of Protein Misfolding

#### Prof. Takis Vlamos - Ionian University, Greece - Director, BiHELab, Bioinformatics and Human Electrophysiology Lab

The classification of various autoimmune diseases according to the misfolding of specific proteins is following the existing proof of their connection. Yet, the misfolding is not being modeled according to geometry but according to the problems arised by the energy flows. The proteins can be unfolded with a parallel production and measurement of approximately 80.000 energy steady states and could be compared with unfolded well operating proteins. The definition of a much smaller length of a protein which may contain the misfolding is crucial for transforming research-oriented patterns to diagnostic tools. Creating new isomorphic representations of the mathematical modeling of the energy form of proteins can provide us with matching criteria for the tracing of protein misfolding in much smaller scales.

# A Biased Overview of a Power-Law Entropy

#### Professor N. Kalogeropoulos - Weill Cornell Medicine - Qatar

The Havrda-Charvat / Daroczy / Lindhard-Nielsen / Cressie-Read / Tsallis entropic functional has attracted some attention during the last 25 years. Professor N. Kalogeropoulos will present a biased overview of this functional, having in mind its potential applicability in the statistical physics of particles and fields.

# Gravitational Waves and General Relativity for All: No Physics Background Required

#### Dr. Shohini Ghose - Wilfrid Laurier University

In September 2015, one of the most precise measurements in history told us about one of the most powerful events in the universe: the collision of two black holes that produced gravitational waves over a billion years ago. But what are gravitational waves and why should we care? This talk will explain the beautiful conceptual simplicity of Einstein's theory of General Relativity, his prediction of gravitational waves, and how this discovery can change our understanding of the universe. No prior knowledge of physics is required. Bring your curiosity.

# Do Billionaires Compute Eigenvalues? 20 Years of Google's PageRank Saga

#### Dr. Ilias Kotsireas - Wilfrid Laurier University

A significant part of Google's early success in the realm of search engines is attributed to the PageRank algorithm, invented 20 years ago. We will explain the concepts behind the PageRank algorithm, that are necessary to gain a thorough understanding of its inner workings, including how to build the corresponding Google matrix. We will illustrate the execution of the PageRank algorithm with an example. Then we will describe how the ranking of websites in Google's search engine arises.

# Semiconductor Epitaxy: driving fundamental discoveries and innovative applications

#### Dr. Zbig Wasilewski - University of Waterloo

Semiconductor research has been one of the most influential driving forces behind pure and applied science for more than half a century. Studies of the elementary and collective excitations, or quasiparticles, in semiconductor-based man-made artificial universes and nanostructures are now one of the hottest research areas in physics. The fruits of the semiconductor science and technology have profound influence on everything from individual lifestyles to the entire civilizations which are increasingly dependent on fiberoptic world-wide web highways, smartphones, personal computers, digital cameras, medical diagnostic instruments, photonic, electronic and magnetic sensors, ultra-bright LEDs, LED flat-panel displays and TVs, and solar-panel power stations, to mention just a few. None of that would have come into existence if it were not for the continuing progress in the material science, and in particular advancements in the epitaxial technologies. This seminar will discuss the principles behind semiconductor epitaxy and give a condensed overview of the current state-of-the art.

# Femtomedicine in Cancer: Discovery of New Antitumor Molecules for Natural Targeted Chemotherapy and Radiotherapy of Cancers

#### Dr. Qing-Bin Lu - University of Waterloo

The conquest of cancer continues to pose great challenges to medical science. There is a compelling need for innovative cancer research integrating biomedical sciences with physical sciences in order to ultimately conquer cancer. Femtosecond (fs) (1fs=10 15 s) time-resolved laser spectroscopy (fs-TRLS) is a direct technique to visualize molecular reactions in real time1. Femtomedicine (FMD), which fuses fs-TRLS with biomedical sciences, was recently coined to advance fundamental understanding and therapies of human diseases notably cancer.

# Constructing the Shadow Geometry of the New W(23,16)

#### Dr. Giora Dula - Netanya College, Israel

A weighting matrix of length n and weight k denoted W(n,k) is an orthogonal {0,±1} matrix with rows of length $$\sqrt{k}$$. I would like to report on a new weighting matrix W(23,16), the smallest pair of numbers where the existense of the weighting matrix is currently not known. I will survey the details of the paper by the authors. This matrix was found in two stages: the one called finding the geometry which is equivalent to finding W modulu 2, and the whole matrix from the geometry called colouring. In this note we concentrate on the geometry stage.

# How a Physicist Simulates Twitter

#### Dr. Isaac Tamblyn - University of Ontario Institute of Technology

In less than a decade, online social networks such as Twitter and Facebook have dramatically changed how communities and individuals share information. Such networks provide the platform for highly intellectual debates such as the colour of the dress (it is clearly white and gold), rapidly spreading information about natural disasters and missing persons, to darker uses such as the ubiquitous monitoring and profiling of online user discussions, enabling online abuse, and spreading the propaganda of repressive regimes. In this presentation, I will discuss how (and why) a Physicist approaches developing a computational model of a social network.

# Tiny and More Precious: Silver and Gold at Nanoscale - Size and Shape Control, Plasmonic Nanoparticles, and "Superatoms"

#### Prof. Vladimir Kitaev - Wilfrid Laurier University

Matter confined to nanoscale dimensions displays striking and unusual properties. Noble metals feature required stability for comfortable nanoscale fabrication through chemical synthesis. Free electrons of metals give rise to surface plasmon resonance (SPR) that is ultimately tuneable through size and shape control. Upon strong quantum confinement (< 2nm), metal nanostructures display discrete electronic transitions and behave like "superatoms" that feature a lot of similarities with quantum dots.

# The Secrets of Gravity

#### Dr. Paul McGrath - Wilfrid Laurier University

A century ago, Einstein revolutionized our understanding of the universe with his new theory of gravity and spacetime. Since then, fantastic ideas like the Big Bang, dark energy, and the existence of blackholes have been revealed. In this talk, I will explore the puzzle pieces that Einstein put together to discover this new theory and explain how exactly it changed our picture of the universe bringing us to our present day understanding. However, the journey will not stop there. I believe that Einstein's theory is still holding on to a very important secret about the inner workings of nature - a secret which we will need to carefully decipher the meaning of if we ever wish to construct a theory of everything.

# Metamaterials

#### Dr. Marek Wartak - Wilfrid Laurier University

Metamaterials are man-made structures possessing predefined electromagnetic properties. These artificial, engineered media have been under development for about 15 years now. They are composed of sub-wavelength features (meta-atoms), which through their interaction with light lead to unusual optical properties, such as a negative (effective) refractive index. Metamaterials having simultaneously negative electric permittivity and magnetic permeability, which leads to a negative refractive index, have been experimentally constructed, tested and found to be in agreement with theory in frequency regions from the radio all the way to the optical regime. Here, we review the basic premises of these media and the routes that are usually followed towards constructing them. In particular, we explain in some detail how one can create a medium possessing negative permittivity and/or negative permeability. Further, we discuss in some detail applications of those materials and current trends in their fabrications using chemical methods.