DATE
February 1st
February 15 th
SPEAKER
Haydee Salmun
Kamila Wisniewska
Frank Buonaiuto
Earth & Env. Science
TOPIC
Introduction to the STEM Seminar
Review of Catalyst Activities for the semester.
Rip Currents.
February 29 th
March 7 th
March 21 st
April 4 th
April 25 th
May 9 th
Randye Rutberg
Earth & Env. Science
Paleoceanography: A nexus of chemistry, climate, math, physics and modeling.
Y.C. Chen
Physics Seeing through opaque media.
Ioannis Stamos
Computer Science
Algorithms for 3D modeling.
Olympia Hadjiliadis
Mathematics
Dana Sylvan
Statistics
Haydee Salmun
Earth & Env. Science
Sequential on-line detection and classification in 3D Computer Vision.
Space-time modeling.
Final Meeting – Discussion on the
interdisciplinary nature of science.

Catalyst Seminar February 15 th . Frank Buonaiuto, Earth & Env. Science
Title: Rip currents.
Abstract:
Rip currents are complex meteorological and oceanographic phenomenons that pose significant danger to beach goers worldwide. Rip currents are the third largest weather related killer behind hurricanes and tornadoes. According to the United States Lifesaving Association rip currents accounted for almost 23,000 of 71,000 lifeguard rescues in 2000. There have been at least 35 rip current related deaths along the south shore of Long Island within the past decade.
Rip currents are narrow (typically on the order of 10 – 20 m) currents flowing seaward from the surf zone that can attain velocities greater than 1-2 m/s. Rip currents comprise part of the normal wave-driven circulation patterns, and are derived from alongshore variations in wave height.
Therefore, the formation, magnitudes, spacing, persistence and evolution of rip currents responds to all factors that can influence or alter the incoming incident wave energy. These factors include: shoreline orientation, wind speed and direction, astronomical tides, and near shore morphology.
Although the near shore zone is a complex environment in which waves, tides, winds, and morphology are interacting on varying temporal and spatial scales, field observations of rip current activity have provided general conclusions: 1) rip currents typically form when waves approach normal to the shoreline or at a slight angle, and tend to diminish if the angle is to great,
2) the size and intensity of rip currents increases with increasing wave height, 3) high wave energy conditions produce few large rip currents, whereas rips associated with lower wave energy conditions are weaker and more abundant (decreased rip spacing), 4) rip persistence is directly related to incident wave height, period and direction, 5) rip currents may be morphologically controlled once they are formed, 6) rip currents can exhibit long period oscillation or pulsing associated with surf beat, 7) rip current velocities intensify during low tides, and 8) rip currents tend to persist around structures including jetties, groins, and piers.
As previously mentioned there have been at least 35 deaths along the NY Atlantic coast associated with rip currents in the past decade: 4 along Robert Moses State Park, 3 at Jones beaches, 7 in Long Beach, 7 at Coney Island and 14 along the Rockaway shoreline.
Catalyst Seminar February 29 th . Randye Rutberg, Earth & Env. Science
Title: Paleoceanography: A nexus of chemistry, climate, math, physics and modeling.

Catalyst Seminar March 7 th . Y.C. Chen Physics
Title: Seeing through opaque media
Abstract:
Random scattering of light is what makes materials such as ground glass, milk, thick fog, or human tissue opaque. In these materials, repeated scattering distort the incident wave front so strongly that the information carried by the input light is totally lost. Recent studies show that by manipulating the wave front of the input light, light can be re-converged total a point behind the surface of an opaque object and thereby to allow images to be formed. I will discuss various new techniques used to achieve this holy grail of imaging.
Catalyst Seminar March 21 st . Ioannis Stamos Computer Science
Title: Algorithms for 3D modeling, classification and symmetry detection in 3D-range and
2D-image data.
Abstract:
The automated photorealistic modeling of large-scale scenes, such as urban structures, requires a fusion of range sensing technology and traditional digital photography. This process involves the automated registration and fusion of a large number of geometrically complex 3D range scans and high-resolution 2D images in a common frame of reference, and finally 3D modeling and data simplification. At a higher-level algorithms that can identify classes of objects (for instance tree versus building, car versus person, etc.) or detect symmetries and regularities are very important as well. We will provide an overview of the challenges, and discuss our specific contributions. We will also present results of scanning large urban structures, such as the interior of the Grand Central Terminal and the Park Avenue area around Hunter College.
Catalyst Seminar April 4th. Olympia Hadjiliadis. Brooklyn College, Mathematics.
Title: Sequential on-line detection and classification in 3D Computer Vision.
Abstract:
The topic of interest in this talk is the use of on-line statistical sequential detection techniques in automatic 3D image reconstruction.3 We will begin this presentation by introducing sequential techniques in statistics will stress their importance in applications. In particular, I will contrast the classical hypothesis testing with fixed sample size to sequential decision making and introduce the sequential probability ratio test (SPRT). I will then talk about the problem of quickest detection and introduce the cumulative sum test (CUSUM) and its importance.
As an application of the above techniques we will discuss the problem of automatic 3D image reconstruction through laser scan sequential data. We will first apply appropriately tuned
CUSUMs to distinguish vertical vs. horizontal surfaces. We will then introduce Hidden Markov models to capture vegetation in urban scenes. By applying CUSUMs to detect changes from on
Hidden Markov model to another we will be able to identify the beginning of regions of vegetation. By then applying repeated SPRTs, we will be able to identify the ending of these regions. We are thus able to distinguish vertical vs. horizontal surfaces as well as regions of vegetation by making use of data sequentially.

Catalyst Seminar April 25 th Dana Sylvan, Mathematics and Statistics
Title: Space-time modeling and prediction of probability distribution functions and quantiles for environmental processes.
Abstract:
The study of probability laws or, equivalently, of quantiles of distribution functions, is fundamental in Statistics. When the data are not independent, modeling distribution functions and quantiles become hard mathematical problems, with a wide area of applicability.
Environmental processes were observed to have complex structures, generated by their temporal and spatial dependencies that in many cases show significant departures from normality or stationary behavior. Examples include climatological processes (temperature, precipitation), and air pollution processes (ozone, small particles). Analysis of environmental data received much attention from both applied scientists in many fields, and theoretical statisticians and mathematicians. A theoretical motivation is given by the challenges connected to estimation and prediction for random fields, involving the necessity of flexible models, to account not only for temporal and spatial dependencies, but also for potential space-time interactions and asymmetries. Examples of practical motivations include understanding longterm variations in climate events, and space-time patterns of pollutants' elevated levels. In this talk I will discuss some theoretical and practical aspects of statistical modeling of distribution functions and quantiles for space-time processes, with illustrations on precipitation and air pollution data.