WORM

Unlike hydrozoids, jellyfish are cnidarians that spend their entire lives in the medusa form. Most live in water deeper than the intertidal area, but individuals sometimes stray or wash into the shallow water of the surf. One very unusual type of jellyfish is native to the intertidal zone, the stalked jellyfish (Haliclystus). Instead of the usual medusa form, the body of the stalked jellyfish is attached to the substrate by a stalk on which the medusa is flipped upside down, with the mouth facing up, giving the animal the appearance of a flower. The petals of the flower are eight lobes that are tipped with club-like tentacles. Haliclystus auricula is one kind of stalked jellyfish whose lobes end in hundreds of tentacles. This very small jellyfish, reaching l4 inches (4.45 cm) in height, favors quiet tide pools where it may be found attached to snails, seaweed, or rocks. H. auricula feeds on worms and other small shore animals. 

Marine worms show a remarkable degree of adaptability and have evolved to occupy many intertidal niches. Some species are free swimming, but most live quiet, inconspicuous lives in the sand and beneath rocks or shells. Worms feed in a variety of ways, grazing on algae, preying on other animals, and scavenging dead and decaying material. 

The populations of worms living in intertidal areas fall into two major groups flatworms and segmented worms. Of the 

Flatworms may reproduce in several ways. Some divide asexually by fission, producing two identical offspring. Other species have all-female populations whose eggs develop without fertilization. However, most types of flatworms reproduce sexually. Individual flatworms are hermaphroditic, having both male and female reproductive organs. To cross-fertilize their gametes, two worms copulate, each donating sperm to the other. 

Marine flatworms generally have very poor eyesight. Their eyes are actually sets of light-sensitive eyespots, arranged in pairs of two, four, or six on the anterior end of the body. To get information about the environments, the worms also depend on folds of tissue that create tentacle-like structures. These tissues can detect chemicals in the water, helping the worms navigate and find their food. 

treatment of gravid females with a mixture of penicillin and streptomycin (5000 units of each per milliliter) followed by sterile water rinse and a 1-hr. exposure to 1 1000 aqueous solution of merthiolate. From the merthiolate solution viable larvae were transferred through one or two changes of sterile water (usually containing penicillin) and placed onto slants containing E, coli. Pure cultures were uniformly obtained from two-membered cultures by 3- to 4-hr. exposure to streptomycin (5000 units per milliliter in broth). 

Pure cultures of Rhabditis pellio and R. briggsae (elegans) have been maintained for many transplants on a complex medium (Difco nutrient agar) supplemented with Seitz-filtered liver extract. In the case of the dioecious R. pellio decreased fertility manifested itself eventually, leading to the hypothesis by the authors that the medium was deficient, although 

Chick embryo juice Amino acid-vitamin medium Growth Maturity Second-generation larvae 

Dougherty, J. C. Raphael, and C. H. Alton, Proc. Helminthol. Soc. Wash, 

The practical aspects of insect nutrition have been recognized for years, and a host of reports have appeared dealing with the natural food habits, food selectivity, etc. Extensive reviews of this literature are available.  

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It is water that, in taking different forms, constitutes tlie earth, atmosphere, sky, mountain, gods and men, beasts and birds, grass and trees, animals down to worms, flies and ants,... 

B" -CHfPhlCH,- H H Antlielmiiitic elfective against whip worms 173, 794, 79.5... 

Guinea worms Guimer-Preston zones Guinier radius L-Gulose [6027-89-0]... 

Polymers are only marginally important in main memories of semiconductor technology, except for polymeric resist films used for chip production. For optical mass memories, however, they are important or even indispensable, being used as substrate material (in WORM, EOD) or for both substrate material and the memory layer (in CD-ROM). Peripheral uses of polymers in the manufacturing process of optical storage media are, eg, as binder for dye-in-polymer layers or as surfacing layers, protective overcoatings, uv-resist films, photopolymerization lacquers for repHcation, etc. 

WORM writablenot erasable polymeric or glassy substrates with metal or ahoy layer, dye-in polymer film substrate <51/4 in./ PC0 > 51/4 in. glass, partly PC... 

CD-R (CD-recordable) is a writable, nonerasable disk, also called CD-WORM or CD-WO (CD-write once). Permanent marks are produced by a focused laser beam. The definition of the CD-R format and of the erasable—rewritable EOD /MO-R format is put down in the Orange Book (Philips/Sony). 

The conditions of these target appHcations are fulfihed by WORM-disks. Apart from data compression on a smah volume, WORM filing systems offer the advantage of fast access from the workplace at ah times, including a simplified document search and retrieval strategy. 

A special implementation of the CD-R disk is the Photo-CD by Kodak which is a 5.25 in. WORM disk employing the dye-in-polymer principle for storage of up to 100 sHdes /pictures on a CD (after data compression) with the possibhity of interactive picture processing. 

Writing Techniques. WORM disks differ depending on their data writing techniques, which can be divided into three classes (3) ablative writing, bubble forming, and phase change. 

Fig. 3. WORM media data writing techniques and typical layer constmction (3) (a) ablative writing, DIP concept (4) (b) ablative writing, LIDA technique (5) (c) writing by bubble forming (d) writing by bubble forming, layer arrangement after (6).

Dyes for WORM-Disks. Regarding their memory layer, dye-in-polymer systems show advantages over metal layers in their higher stabiHty, lower toxicity, lower heat conductivity, lower melting and sublimation temperature, and simpler manufacturing technique (substrate coating by sublimation or spincoating). 

The GaAs laser used as light source emits at about 820 nm. Thus dyes in the actual sense are not needed rather, ir-absorbers for the spectmm between 750—850 nm Httie experience is available on this class of dyes, especially as far as their stabiHty is concerned, although much work has been done in this area. Also, infrared sensitive dyes and pigments, used in electrophotography, may be very suitable for WORM disks (8). 

To yield high storage densities, layer thicknesses in the order of the focused laser beam are necessary in the storage medium, measuring about 1 )Tm. In commercial WORM disks based on pure dye layers, layer thicknesses are even lower at about 0.1 )Tm. With thicknesses as low as these, it becomes... 

Fig. 4. Dyes for WORM media (a) hydroxy squaryhum (9,10) (b) SQS = squaryhum core with thiopyrylium end group (11) (c) TPMP ...

In WORM disks, pentamethine and heptamethine are the materials of choice (see Cyanine dyes Polymethine dyes). 

Fig. 6. Dyes for WORM media phthalocyanine derivatives. The basic stmcture (12) of naphthalocyanine derivatives. Y = Si, Ge, Sn, Al, Ga, In, or a transition metal = ORj, OSiR R R, polymer. and represent substituents on the tings of the naphthalene system.

Meta.1 Complexes. The importance of Ni complexes is based on their effectiveness as quenchers for singlet oxygen. Of disadvantage is their low colorfastness and their lower ir-reflectance compared to cyanine dyes (qv) therefore they are used in combination with suitable dyes. Numerous complexes are described in the Hterature, primarily tetrathiolate complexes of Pt or Ni, eg, dithiolatonickel complexes (3). Well known is the practical use of a combination of ben2othia2ole dyes with nickel thiol complexes in WORM disks (Ricoh, TDK) (17). 

The principal use of CD-ROM and WORM disks is essentially substitution of data storage on paper or microfiche. Conservative estimates number the worldwide use for data storage by paper at 91%, microfiche at 4%, and in electronic media at 5%, of which 4% are magnetic and 1% optical media (18). CD-ROM is being used as an electronic counterpart to print media the WORM disk presents itself more and more as a substitute for paper to store archivable, forgery-proof documents. 

Another advantage of PC technology is the plaimed and partially realized use of multiftmction drives for operation of either CD-ROM, WORM, or PC-R disks alternatively in the same disk drive. This is technically feasible, since for reading (in CD-ROM, WORM, PC-R) as well as for writing (WORM, PC-R) similar principles and hardware are used (108). However, the reflectivity change of PC disks (40/70%) is in general lower than the CD-ROM standard (30/70%) requires. 

Fig. 16. Maximum achievable signal-to-noise ratio (SNR) on read-out of different writable optical data storage systems as a function of the writing energy (laser power) (121). SQS = Organic dye system (WORM) PC = phase change system (TeSeSb) MO = magnetooptical system (GbTbFe). See text.

The composition of an optoelectronic memory card (eg. Laser Card of Drexler Technology Corp.) (162) is outlined in Figure 21 (163). Primary elements are polycarbonate foils with thicknesses of 250 to 400 )Tm, respectively, that are employed because of their high operating temperature and their good mechanical, optical, and dielectric characteristics. The OMC can be used as a ROM or a WORM media. Both possibiUties of information deposition can be used separately or in combination. 

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