by Prof. Harald Pfeiffer of the Canadian Institute for Theoretical Astrophysics, 1:30 pm PAB 22.

Gravitational waves are expected to be detected later this decade by the Advanced LIGO experiment. Today’s talk should give us a look ahead. Harald tells me there are already searches on to detect signatures of a population of low mass (less than the mass of the Sun) black holes in the halo of the Milky Way. How such things could possibly have formed is another issue! There is also apparently an uncertainty of a factor of 50(!) in the expected rate of GW signals measurable by Advanced LIGO.

Poster: http://www.physics.uwo.ca/colloquia/Colloquia%20Notices/2011_2012/KOAY%20Research%20Talk.pdf

Western University
DEPARTMENT OF PHYSICS AND ASTRONOMY

PHYSICS & ASTRONOMY COLLOQUIUM

Date:          Thursday, 9^th February 2012
Time:          1:30 p.m.
Location:    Physics & Astronomy Seminar Room 22

Dr. Cheng Guan Koay
University of Wisconsin School of Medicine & Public Health

Madison, Wisconsin

“Diffusion Magnetic Resonance Imaging: From optimal acquisition design to signal extraction”

ABSTRACT

Diffusion Magnetic Resonance Imaging (MRI) in combination with functional MRI promises a whole new vista for scientists to investigate noninvasively the structural and functional connectivity of the human brain—the human connectome, which had heretofore been out of reach. As with other imaging modalities, diffusion MRI data are inherently noisy and its acquisition time-consuming. Further, a faithful representation of the human connectome that can serve as a predictive model requires a robust and accurate data-analytic pipeline. This talk will touch on recent advances on two important segments of a complex diffusion MRI data-analytic pipeline: temporally and spatially optimal acquisition design via deterministic approaches, and accurate signal extraction through a framework that is capable of breaking the noise floor.

My apologies for having the wrong year in the previous notice!              

Poster: http://www.physics.uwo.ca/colloquia/Colloquia%20Notices/2011_2012/STEVENS%20Research%20Talk.pdf

Western University
DEPARTMENT OF PHYSICS AND ASTRONOMY

PHYSICS & ASTRONOMY COLLOQUIUM

Date:          Tuesday, 7^th February 2012
Time:          1:30 p.m.
Location:    Physics & Astronomy Seminar Room 22

Dr. Todd Stevens
Robarts Research Institute
Imaging Research Laboratories

“Accelerated high angular resolution diffusion imaging using compressed sensing: Crossing fiber data you can trust in a time you can afford”

ABSTRACT

There are a large number of neuroscience and neurology applications that would benefit from robust functional brain connectivity information. To substantiate and enhance functional MRI (fMRI) analyses of neural circuitry, diffusion–weighted MRI can provide information about the underlying white matter connectivity architecture. However, conventional diffusion tensor imaging (DTI) techniques are not capable of characterizing the diffusion of voxels that contain multiple crossing fibers—a situation that is known to occur in up to 30% of voxels acquired with typical diffusion imaging resolutions. Consequently, network tractography information generated from DTI data is prone to inaccuracies.

High angular resolution diffusion imaging (HARDI) schemes more finely sample the diffusion field to allow for more complete characterization of intra–voxel crossing fibers. The principal drawback of HARDI techniques is long scan times that preclude the acquisition of both fMRI and diffusion data in a reasonable exam time. Advantageously, diffusion information is amenable to dramatic acquisition accelerations using a new approach called compressed sensing (CS). Using CS–based acquisitions, accurate tractography maps based on HARDI information can be acquired at the lower acquisition costs of typical DTI.

This talk will introduce the concepts of CS-HARDI as well as provide details on the development roadmap for establishing and validating this technique, and will briefly describe some potential applications of this technique in the context of existing research interests at Western.

Poster: http://www.physics.uwo.ca/colloquia/Colloquia%20Notices/2011_2012/STEVENS%20Research%20Talk.pdf

Western University
DEPARTMENT OF PHYSICS AND ASTRONOMY

PHYSICS & ASTRONOMY COLLOQUIUM

Date:          Tuesday, 7^th February 2011
Time:          1:30 p.m.
Location:    Physics & Astronomy Seminar Room 22

Dr. Todd Stevens
Robarts Research Institute
Imaging Research Laboratories

“Accelerated high angular resolution diffusion imaging using compressed sensing: Crossing fiber data you can trust in a time you can afford”

ABSTRACT

There are a large number of neuroscience and neurology applications that would benefit from robust functional brain connectivity information. To substantiate and enhance functional MRI (fMRI) analyses of neural circuitry, diffusion–weighted MRI can provide information about the underlying white matter connectivity architecture. However, conventional diffusion tensor imaging (DTI) techniques are not capable of characterizing the diffusion of voxels that contain multiple crossing fibers—a situation that is known to occur in up to 30% of voxels acquired with typical diffusion imaging resolutions. Consequently, network tractography information generated from DTI data is prone to inaccuracies.

High angular resolution diffusion imaging (HARDI) schemes more finely sample the diffusion field to allow for more complete characterization of intra–voxel crossing fibers. The principal drawback of HARDI techniques is long scan times that preclude the acquisition of both fMRI and diffusion data in a reasonable exam time. Advantageously, diffusion information is amenable to dramatic acquisition accelerations using a new approach called compressed sensing (CS). Using CS–based acquisitions, accurate tractography maps based on HARDI information can be acquired at the lower acquisition costs of typical DTI.

This talk will introduce the concepts of CS-HARDI as well as provide details on the development roadmap for establishing and validating this technique, and will briefly describe some potential applications of this technique in the context of existing research interests at Western.

TODAY

The University of Western Ontario
DEPARTMENT OF PHYSICS AND ASTRONOMY

PHYSICS & ASTRONOMY COLLOQUIUM

Date:           Thursday, 26^th January 2011
Time:          1:30 p.m.
Location:    Physics & Astronomy Seminar Room 22

Dr. Blaine Chronik
Physics & Astronomy Department
The University of Western Ontario

“Variable fields in MRI: progress, opportunities, and challenges”

ABSTRACT

Over the past 8 years or so, we have worked on Magnetic Resonance Imaging methods and technology which are distinguished because of their focus on the use of rapidly varying, strong magnetic fields.

Our approach has evolved, from what was purely “laboratory,” preclinical implementation, to our current efforts which focus on systems for use in clinical MR scanners.

In this talk, I will describe a new method of MRI in which we strive to produce very specific MR image contrast due to the presence of a chemical contrast-agent, only when that agent is bound to target molecules of interest. This represents a means to achieve contrast specificity in MRI that has not been previously available. The method is called “dreMR”: delta relaxation enhanced MR (reference: Magn Reson in Med, 61(4):796-8002 (2009)). This technique requires a major change to the MRI system architecture – specifically, the ability to vary the main magnetic field strength as a function of time. I will review the concept behind the method, our preclinical technological implementation, and we will discuss the applicability of the method for human-scale subjects. Along the way, we will also review the wider range of MR system developments we’ve worked on, and some of our future projects.

Coffee & cookies will be provided.

Department of Physics and Astronomy

PhD Public Lecture

Matthew Fox

Supervisor: Dr. Giles Santyr

“Hyperpolarized noble gas magnetic resonance imaging and dynamic spectroscopy for investigation of rat models of lung inflammation”

DATE:         FRIDAY, 3^rd February 2012

TIME:          1:30 p.m.

PLACE:      Robarts 2^nd Floor Fisher Conference Room

All are welcome to attend.

Poster: http://www.physics.uwo.ca/colloquia/Colloquia%20Notices/2011_2012/CHRONIK%20Colloquium.pdf

The University of Western Ontario
DEPARTMENT OF PHYSICS AND ASTRONOMY

PHYSICS & ASTRONOMY COLLOQUIUM

Date:           Thursday, 26^th January 2011
Time:          1:30 p.m.
Location:    Physics & Astronomy Seminar Room 22

Dr. Blaine Chronik
Physics & Astronomy Department
The University of Western Ontario

“Variable fields in MRI: progress, opportunities, and challenges”

ABSTRACT

Over the past 8 years or so, we have worked on Magnetic Resonance Imaging methods and technology which are distinguished because of their focus on the use of rapidly varying, strong magnetic fields.

Our approach has evolved, from what was purely “laboratory,” preclinical implementation, to our current efforts which focus on systems for use in clinical MR scanners.

In this talk, I will describe a new method of MRI in which we strive to produce very specific MR image contrast due to the presence of a chemical contrast-agent, only when that agent is bound to target molecules of interest. This represents a means to achieve contrast specificity in MRI that has not been previously available. The method is called “dreMR”: delta relaxation enhanced MR (reference: Magn Reson in Med, 61(4):796-8002 (2009)). This technique requires a major change to the MRI system architecture¾specifically, the ability to vary the main magnetic field strength as a function of time. I will review the concept behind the method, our preclinical technological implementation, and we will discuss the applicability of the method for human-scale subjects. Along the way, we will also review the wider range of MR system developments we’ve worked on, and some of our future projects.

Coffee & cookies will be provided.

TODAY!

Department of Physics and Astronomy

PhD Public Lecture

Ali Hatef

Supervisor: Dr. Mahi Singh

“Quantum Coherence and Interference in Metallic Photonic Crystals and Hybrid Systems”

DATE:            FRIDAY, 9^th December 2011

TIME:             1:00 p.m.

PLACE:         Physics & Astronomy Room 22

All are welcome to attend.

TODAY

PHYSICS & ASTRONOMY COLLOQUIUM

Date:           Thursday, 8^th December 2011
Time:          1:30 p.m.
Location:    Physics & Astronomy Seminar Room 22

Dr. Nazir P. Kherani
Electrical and Computer Engineering
University of Toronto

“Photovoltaic – Photonic Crystal Interplay”

ABSTRACT

On the steps of Volta’s discovery of the voltaic effect in 1800 and Becquerel’s discovery of the photovoltaic effect in 1839, followed more than a 100 years of research before scientists at Bell Laboratories developed the first silicon pn junction photovoltaic device. In the intervening 60 years great strides have been made in the field of photovoltaics (PV). Today it is recognized that PV can become a significant component of sustainable terrestrial energy sources. It is non‐polluting, environment friendly, and its fuel is distributed relatively uniformly and is free.

However, with the continual drive towards grid‐parity and thus reduction of cost per peak watt, a range of novel approaches are being pursued which offer the potential combination of reduction in material and processing costs and maximal solar utilization. In this context, photonic crystals present interesting light propagation control that could make them amenable to novel photovoltaic‐photonic crystal integrations. Recently, we have proposed a novel class of photonic crystals, called selectively transparent and conducting photonic crystals (STCPCs). These STCPCs, a significant advance over existing 1D PCs, combine intense wavelength selective broadband reflectance with the transmissive and electrically conductive properties of sputtered transparent conducting oxides. This integration of optical and electrical functionalities into a single device element has opened the way for performance enhancement in a range of optoelectronic devices including photovoltaics.

The talk will provide an overview of photovoltaics, highlighting a range of device material systems and cell concepts and their associated strengths and challenges. The presentation will then focus on our recent studies on the potential use of photonic crystals in PV devices, with an emphasis on their application in thin film silicon solar cells; specifically, their application of selectively transparent and conducting photonic crystals in photovoltaics and allied devices will be underlined. Allied investigations into low‐cost high‐efficiency ultra‐thin silicon photovoltaics and recent laser-assisted synthesis of tailorable light trapping patterns in silicon will also be presented.

Coffee & cookies will be available, courtesy of