For integers g ≥ 3, k ≥ 2, call a number N a (g, k)-reverse multiple if the reversal of N in base g is equal to k times N . The numbers 1089 and 2178 are the two smallest (10, k)reverse multiples, their reversals being 9801 = 9 · 1089 and 8712 = 4 · 2178. In 1992, A. L. Young introduced certain trees in order to study the problem of finding all (g, k)-reverse multiples. By using modified versio...

C”n”enti”nal surfxe rcnecrion methods CO‘ derccting and supprc*,ing short-period interbed multiples in Lkvunian reef explorati”” often race difficulties. Predictive dec”n”“lution and C”P stacking of surface reflection data S”metimei d” not suppress the multiples that “brcurc primary reef re”ccti”nl. A Yenicd seibnlic pmmng (VW) method which can help t” differcn,ia,r primarier and multiples is c...

Standard model-based redatuming techniques consist in applying time shifts to the surface data, to simulate an acquisition made at depth. The time shifts are computed using prior knowledge of the overburden, such as a macro velocity model. These techniques allow focusing of the direct waves at the new datum, but the focus can be degraded because of surface multiples and internal multiples in th...

Twin Research and Human Genetics Volume 9 Number 6 pp. 868–874 T Sri Lankan Twin Registry began as a volunteer register in 1997. Previously, we have shown doorto-door surveys as the best option to build a population-based twin register of older, adult twins. Our aim was to build a population-based twin register in the Colombo district and use it for twin studies on common mental disorders. We a...

AIMS Assisted reproduction led to an enormous increase of multifetal gestation. Apart from the obstetrical risks the physical, psychological and socioeconomic problems in families after the birth of higher order multiples often lack attention. STUDY DESIGN Anonymous questionnaires were sent to 92 families who had delivered higher order multiples at our hospital (1983--1998). In a retrospectiv...

Recently, a new approach to multiple removal has been introduced: estimation of primaries by sparse inversion (EPSI). Although based on the same relationship between primaries and multiples as surface-related multiple elimination (SRME), it involves quite a different process: instead of prediction and subtraction of multiples, in EPSI the unknown primaries are the parameters of a large-scale in...

The primary only imaging condition (POIC) can effectively remove some of the migration artifacts generated by multiple energy in the far-offset data. The multiples predicted by a POIC filter in the far-offset data are used to predict and eliminate the near-offset multiples in the τ−p domain with the Radon transform. The hybrid algorithm is tested on a simple synthetic example and the 2-D SMAART...

Multiple reflections provide redundant, and sometimes additional, information about the corresponding primary reflections. I implement a least-squares inversion scheme to jointly image (by normal moveout) primaries and multiples, with the goal of enforcing consistency between the images and the input data. Furthermore, to effect noise (“crosstalk”) suppression, I introduce a novel form of model...