March 2007     ISSUE 21

 

 

 MEETINGS: 

10th Conference on Electromagnetic and Light Scattering by Nonspherical Particles (ELS-10) 17~23 June 2007,  Bodrum, Turkey

 Important ELS-10 deadlines:

March 23, 2007: Electronic copies of extended abstracts to M. Mishchenko or G. Videen

May 1st, 2007 is one important deadline for several things as given on the web site http://www.engr.uky.edu/~menguc/ELSX/

Please make your flight bookings well in advance and send the conference registration form (given on the web site) to the Secretariat of ICHMT (E-Mail: ichmt@ichmt.org ) before the deadline. June is a high tourist season for Bodrum and we must inform the hotel (Hapimag Resort Sea Garden) of the room booking at least a month in advance. We cannot guarantee to meet last-minute requests after the deadline. We will send each of you a confirmation note and a check list after the deadline, May 1st.

You will not be met at the airport and no transportation to the Hotel Hapimag Resort Sea Garden will be provided unless you have specifically asked for that service. NEYZEN TRAVEL & YACHTING will meet participants arriving at the Bodrum Airport upon request. Please fill in and send the request form on the Web site  http://www.neyzen.com.tr/rad-07  before May 1st, 2007. 

Another deadline just around the corner is March 15th, 2007. It is the deadline for sending the reservation form (also given on the Web site) to NEYZEN TRAVEL & YACHTING for post-symposium tours to Istanbul and Cappadocia. Please see the Web site,  http://www.neyzen.com.tr/rad-07  

For daily excursions to Bodrum and Ephesus, and daily yacht tour, the deadline for sending the reservation form is May 1st, 2007.

We look forward to seeing you soon in Bodrum.

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New Papers:

Nikolay. V. Voshchinnikov,  Gorden Videen,  and Thomas Henning

Effective medium theories for irregular fluffy structures: aggregation of small particles

E-mail contact: nvv@astro.spbu.ru

Accepted by Applied Optics;  http://xxx.lanl.gov/astro-ph/0703023

We study the extinction efficiencies as well as scattering properties of particles of different porosity. Calculations are performed for porous pseudospheres with small size (Rayleigh) inclusions using the discrete dipole approximation. Five refractive indices of materials covering the range from 1.20+0.00i to 1.75+0.58i were selected. They correspond to biological particles, dirty ice, silicate, amorphous carbon and soot in the visual part of spectrum. We attempt to describe the optical properties of such particles using Lorenz-Mie theory and a refractive index found from some effective medium theory (EMT) assuming the particle is homogeneous. We refer to this as the effective model. It is found that the deviations are minimal when utilizing the EMT based on the Bruggeman mixing rule. Usually the deviations in extinction factor do not exceed ~ 5% for particle porosity P= 0 - 0.9 and size parameters xporous = 2πrs,porous/λ  ≤  25. The deviations are larger for scattering and absorption efficiencies and smaller for particle albedo and asymmetry parameter. Our calculations made for spheroids confirm these conclusions. Preliminary consideration shows that the effective model represents the intensity and polarization of radiation scattered by fluffy aggregates quite well. Thus, the effective models of spherical and non-spherical particles can be used to significantly simplify computations of the optical properties of aggregates containing only Rayleigh inclusions.