Letters.Firmly planted A mild objection: The article on lichens Lichens Symbiotic associations of fungi (mycobionts) and photosynthetic partners (photobionts). These associations always result in a distinct morphological body termed a thallus that may adhere tightly to the substrate or be leafy, stalked, or hanging. ("Yikes yikes interj. Used to express mild fear or surprise. [Origin unknown.] ! The lichens went flying," SN: 8/26/00, p. 140) mentioned that lichens are composed of fungi and algae algae (ăl`jē) [plural of Lat. alga=seaweed], a large and diverse group of primarily aquatic plantlike organisms. These organisms were previously classified as a primitive subkingdom of the plant kingdom, the thallophytes (plants that , a type of protist protist Any member of a kingdom (Protista) of diverse eukaryotes, including algae, protozoans, and lower fungi (see fungus). Most are single-celled organisms, though the algae tend to be multicellular. , as if it were a given that all agree to. While it is true that the majority of taxonomists would classify an alga as a protist, there still are a large number of modern taxonomists who place algae within the kingdom Plantae. The Protista schema is certainly not yet unanimous. Jedidiah Palossari Dearborn, Mich. Mirror image After reading "Through the looking glass" (SN: 9/9/00, p. 173), I am sure others must have also wondered if the "Tunguska meteor" that struck in Siberia in June 1908 might have been a mirror meteor. The mirror-asteroid strike described in the article sounds very much like descriptions of the event: tremendous energy and no impact crater. If a mirror object were to strike the surface of the moon, Mars, or Venus, would this cause an explosive event that could be easily distinguished from a normal impact that would create a crater? Is there any evidence of such events? David Reynolds Porter, Texas Some researchers have indeed speculated that the Tunguska event might have been caused by a mirror object striking Earth. I don't know Don't know (DK, DKed) "Don't know the trade." A Street expression used whenever one party lacks knowledge of a trade or receives conflicting instructions from the other party. of any way that this can be proven, but looking for Looking for In the context of general equities, this describing a buy interest in which a dealer is asked to offer stock, often involving a capital commitment. Antithesis of in touch with. explosions of any sort that have no apparent visible source could yield evidence of mirror projectiles, some researchers argue. --R. Cowen Poison passion While the letters by Orient and Woods in the Sept. 9 issue (p. 163) railing against the prohibitions of DDT DDT or 2,2-bis(p-chlorophenyl)-1,1,1,-trichloroethane, chlorinated hydrocarbon compound used as an insecticide. First introduced during the 1940s, it killed insects that spread disease and feed on crops. were probably published in the interest of editorial balance ("The case for DDT," SN: 7/1/00, p.12), scientific debate is not well served when political beliefs and flawed logic are substituted for reasoned discourse based on real data. The well-documented decline of the California brown pelican and its correlation with DDT use is no longer debated. Bioaccumulation bi·o·ac·cu·mu·la·tion n. The increase in the concentration of a substance, especially a contaminant, in an organism or in the food chain over time. of DDT is demonstrated on a regular basis. DDT, banned in the United States over 25 years ago, is routinely detected at high concentrations in investigations of former pesticide manufacturing and shipping facilities and in low concentrations in many locations. Orient denies these phenomena. Woods attempts to bolster his argument by stating that compounds from red algae could be misidentified by gas chromatography as DDT. However, most environmental samples don't contain red algae. Additionally, if the identity of a chemical is uncertain by gas chromatography alone, environmental labs typically will confirm the analysis using mass spectroscopy. As a geochemist well into my second decade of environmental consulting, I feel that environmental regulations in some cases are overly strict or misapplied by individual regulators, and environmental decisions are often overly influenced by emotional arguments both pro and con PRO AND CON. For and against. For example, affidavits are taken pro and con. . The U.S. ban on the sale and use of DDT is not one of these cases. Jay A. Ach San Francisco, Calif. |
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