Worker caste

The queen is usually reproductively dominant within the colony and uses chemical cues as both primer and releaser pheromones to suppress the production or fecundity of other sexuals, inhibit reproduction by worker castes, modulate reproductive behaviors (e.g., inhibit swarming and orient swarms), attract males, regulate worker tasks and worker ontogeny, and produce host repellents in slave-making species. Considering the importance of queen semiochemicals in social hymenoptera, few queen pheromones have been chemically identified. The queens of most social hymenopteran colonies are attractive to workers, allowing them to be properly tended as well as to facilitate the dissemination of other pheromone cues. However, the retinue pheromone has been chemically identified in very few species. In the 1980s, queen pheromone components were identified in the fire ant, Solenopsis invicta [91,92], and in the Pharaoh s ant, Monomoriumpharaonis [93]. 

All these features parallel those found in eusocial insects, and the naked mole-rat has been recognized as the only eusocial vertebrate (Jarvis, 1981). Naked mole-rats resemble termites more than hymenopterans they are diploid, male and females form the worker castes, the young contribute to the colony labor, some workers reproduce if the breeding female is removed, and theyoung obtain food by coprophagy (Jarvis, 1981). A similar social system exists in the Damara-land mole-rat, Cryptomys damarensis (Bennett and Jarvis, 1988). 

Reticulitermes has been most extensively studied using chemotaxonomic analysis of CHCs, particularly in the USA. One reason for this interest is the great economic impact of the genus and difficulty in describing the different species, which are similar morphologically, especially with their worker caste. The first description of CHCs in a Reticulitermes species involved R. flavipes, another major pest species in the USA (Howard et al., 1978). It was shown that R. flavipes displayed a specific conjugated diene, i.e., (Z,Z)7,9-C25 2, that was... 

Not only queens express these profiles. Intermediate forms between queen and worker castes, so-called intermorphs, specialize in trophic egg-laying in Crematogaster smithii (Heinze etal., 1999). Interestingly, they produce a queen-like profile, while workers produce a profile that differs from those of reproductive queens and intermorphs (Oettler et al., 2008). 

The various worker castes frequently carry out different roles in defence. In many species there is a specialized soldier caste, whose behavior and exocrine chemistry may differ markedly from those of other workers (e.g.. Law et aL, 1965). Workers of the African weaver ant Oecophylla longinoda are dimorphic the major workers forage and defend the nests and territory, while the minor workers serve as nurses to the brood, and are rarely seen outside the nests (Weber, 1949). The blend of compounds in the mandibular glands differs markedly between the two castes (Bradshaw et aL, 1979b) all the compounds present in minor workers are alcohols, and three of the four compounds most important in alarm communication between majors are absent, namely hexanal, 3-undecanone and 2-butyl-2-octenal. The only abundant compound held in common is 1-hexanol, and the secretion in minor workers is largely made up of the monoterpene nerol. Both nerol and 1-hexanol are highly repellent to minor workers, and they are thus displaced from sources of both minor and major worker secretions. Nerol is a powerful attractant and arrestant for major workers. 

The Kalotermitidae are dry-wood termites. They are considered here with the Termopsidae because their caste structure and mode of life are essentially similar. Both families have soldiers with powerful biting mandibles (Fig. 16.9), there is no fixed worker caste, and the colony gains its main protection from the tree, stump or log in which it excavates galleries. The European species Kalo-termes flavicollis has been used extensively in the study of caste determination mechanisms. 

It has been claimed that the D-D fusion reaction occurs when D2O is electroly2ed with a metal cathode, preferably palladium, at ambient temperatures. This claim for a cold nuclear fusion reaction that evolves heat has created great interest, and has engendered a voluminous titerature filled with claims for and against. The proponents of cold fusion report the formation of tritium and neutrons by electrolysis of D2O, the expected stigmata of a nuclear reaction. Some workers have even claimed to observe cold fusion by electrolysis of ordinary water (see, for example. Ref. 91). The claim has also been made for the formation of tritium by electrolysis of water (92). On the other hand, there are many experimental results that cast serious doubts on the reahty of cold fusion (93—96). Theoretical calculations indicate that cold fusions of D may indeed occur, but at the vanishingly small rate of 10 events per second (97). As of this writing the cold fusion controversy has not been entirely resolved. 

The final example is shown in Fig. 10.86. Several workers are breaking gates off of castings on the conveyor by hand. Much dust is generated by this operation and the dust rises due to buoyancy. To remove the dust, an exterior hood was placed beside the conveyor and a supply inlet was placed above the workers. The supply airflow is blown toward the breathing zone of the workers and the dust source. In this case, as the workers and the dust source are located within the supply airflow, the airflow functions to supply the workers with clean air and to transport the dust toward the exhaust inlet. The velocity of supply air is relatively low, 1.1 m s , and the exhaust velocity at the hood face is 2.75 m s . The dimensions of the system are indicated in the figure, and the depth of the device is 6.0 m (compare with Sections 10.3.3 and 10.4.6). 

A number of studies have recently been devoted to membrane applications [8, 100-102], Yoshikawa and co-workers developed an imprinting technique by casting membranes from a mixture of a Merrifield resin containing a grafted tetrapeptide and of linear co-polymers of acrylonitrile and styrene in the presence of amino acid derivatives as templates [103], The membranes were cast from a tetrahydrofuran (THF) solution and the template, usually N-protected d- or 1-tryptophan, removed by washing in more polar nonsolvents for the polymer (Fig. 6-17). Membrane applications using free amino acids revealed that only the imprinted membranes showed detectable permeation. Enantioselective electrodialysis with a maximum selectivity factor of ca. 7 could be reached, although this factor depended inversely on the flux rate [7]. Also, the transport mechanism in imprinted membranes is still poorly understood. 

The diffusion of oxygen through polymer films has been examined by a number of workers. Guruviah measured the permeability to oxygen of films cast from five paints (Tabic 14.4) and compared the results with the... 

More recently, many workers have concentrated on controlling the size and shape of particles, with an eye on industrial applications, where such features must be well defined and controllable. Many shapes have been made, including fibres, spheres, plates, as well as membranes cast on... 

Hopefully the reader will benefit from this manifold approach, which casts light on the topic from a range of perspectives. Many of the contributors were originally physicists or chemists who became curious about particular applications, while an increasing minority of workers are contributing expertise from a Chemical Engineering aspect and introducing questions that are completely new to the fundamental researcher. 

Tetrahydrofuran has been reported to exhibit an absorption maximum at 280 nm (52,56), but several workers have shown that this band is not produced by the purified solvent (30,41,57). Oxidation products from THF have been invoked in order to account for the appearance of the 280-nm band in PVC films that are solvent-cast from THF in air (57. 581. However, in some reported cases (56,59), this band was undoubtedly produced, at least in part, by a phenolic antioxidant (2.6-di-tert-butyl-p-cresol)(59) in the solvent. Since certain -alkylphenols have now been shown to be powerful photosensitizers for the dehydrochlorination of PVC (60), it is clear that antioxidant photosensitization might well have been responsible for some of the effects attributed previously (56) to THF alone. On the other hand, enhanced rates of photodegradation under air have also been observed for PVC films cast from purified THF (57), a result which has been ascribed to radical formation during the photooxidation of residual solvent (57,61). Rabek et al. (61) have shown that this photooxidation produces a-HOO-THF, a-HO-THF, and y-butyro-lactone, and they have found that the hydroperoxide product is an effective sensitizer for the photodehydrochlorination of PVC at X = 254 nm (61). 

Immobilization of the bilayer membranes as thin solid films is required when the bilayer membranes are used as novel functional materials. Casting method is a simple way to immobilize the bilayer membrane on a solid support from an aqueous solution by drying. Polymer film is easily prepared when the cast film of polymerizable bilayer membrane is polymerized. A free standing polymer film prepared by photo polymerization of the cast film of diacetylene amphiphiles was reported by O Brien and co-workers [34]. Composition with macromolecular materials is another way of polymer film preparation. Bilayer membranes are immobilized as polymer composites by the following physical methods ... 

Nienow and Elson (1988) have reviewed work done mainly by them and their co-workers on the mixing of non-Newtonian liquids in tanks. The above approach for inelastic, shearing thinning liquids has been largely substantiated but considerable doubt has been cast over using this method for dilatant, shear thickening materials. 

Table 4.6 shows three of the money circuits that can be identified in Marx s schema. The first circuit (Ft) is the initial impact of capitalist outlays, as introduced in Table 4.5. For example, capitalists in Department 1 outlay 1,000 units of money, 400 of which are directed to the purchase of capital goods from itself and 600 from the purchase of consumption goods (for worker and capitalist consumption) from Department 2. In addition to the 400 units that Department 1 sells to itself, another 100 emits of capital goods are sold to Department 2. The total receipts from these sales are only 500 in the first circuit, precisely 500 short of the amount it lays out. However, Department 2 gets receipts of 1,250, which is more than its total outlay of 750. Overall, the 1,750 cast into circulation returns back to the capitalist class.

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