The louse

The piezoelectric stepper, nicknamed the louse, was the first successful stepper used in UHV STM (Binnig and Rohrer, 1982). A schematic of the louse is shown in Fig. 12.1. As shown, the actuating element of the louse is a piezoelectric plate (PP), which can be expanded or contracted by applying a voltage (100 to 1000 V). It is resting on three metal feet (MF), separated by high-dielectric-constant insulators (I) from the metal ground plate (GP). 

In virtue of the small physical size of the louse, a pocket-size STM was developed and incorporated in an UHV scanning electron microscope chamber (Gerber et al., 1986) see Fig. 12.2. The actual dimensions are 10X6X4 cm Many of the spectacular STM images were obtained by the pocket-size STM, or slightly improved versions of the original pocket-size 

for example, Feenstra, Thomson, and Fein (1986), Chiang, Wilson, Gerber, and Hallmark (1988). At the time being, these instruments are still working well. 

Another advantage of the louse is that two-dimensional coarse motions can be achieved. By placing the pocket-size STM in a vacuum chamber with a scanning electron microscope (SEM), it is possible to locate interesting features on the sample surface with the tip. This enabled several authors to locate the interface of a device, for example, Muralt et al. (1987), Salmink et al. (1989), and Albrektsen et al. (1990). 

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The natural reservoirs are humans, and within the United States, flying squirrels. R. prowazekii is not transmitted by the bite of the louse, but rather by contamination of the bite, or other open wounds, by the infected feces of the louse. Lice begin releasing rick-ettsiae in their feces within 6 days after becoming infected. Lice die within 2 weeks after becoming infected. Rickettsiae may remain viable in dead lice for weeks. This is a biosafety level 3 agent. 

Fig. 12.2. The pocket-size STM. Vibration isolation and damping are achieved by a stack of stainless-steel plates separated by viton O rings (not shown) in between. On the top metal plate are the louse and the piezoelectric tripod. 1, A metal plate with the sample holder, with only one of the three screws tightened. 2, Piezoelectric plate. 3, Annodized aluminum feet. 4, Tip holder. 5, The current lead. Viton pieces on the edges of the metal plates are used for isolating the vibration transmitted through the wires. (After Gerber et al., 1986.)...

The piezoelectric stepper described in the previous section, the louse, is a somewhat complicated device, which requires substantial effort to make it work. In many surface-science experiments, the actual location on the sample surface does not matter. A one-dimensional stepper is sufficient. In its simplest form, a micrometer, or a fine-pitch lead screw, can make controlled steps of a few micrometers. However, it is extremely difficult for STM, where the range of the z-piezo is typically of the order of O.ljL/m. 

Figure 23-21 Phthiriasis palpebrarum attached to lid. Head (large black arrowy, claws grasping eyelashes (small white arrows ). Fecal matter may be viewed as a dark spot located in the lower end of the louse abdomen (large white arrow). (Courtesy Dr. Laura Kenyon, University of Houston, College of Optometry.)...

Wild birds have a different type of lice, such as the louse, Esthioptervm crassicorne, which is a parasite of the blue-winged teal, Anas discors, a native species of duck. 

The capitalist is the direct exploiter of the workers not only the direct appro-priator, but the direct creator of surplus-labour. But since (for the industrial capitalist) this can only take place through and in the process of production, he is himself a functionary of this production, its director. The landlord, on the other hand, has a claim - through landed property (to absolute rent) and because of the physical differences of the various types of land (differential rent) - which enables him to pocket a part of this surplus-labour or surplus-value, to whose direction and creation he contributes nothing. Where there is a conflict, therefore, the capitalist regards him as a mere superfetation, a Sybarite excrescence, a parasite on capitalist production, the louse that sits upon him. ... 

Pubic or crab lice are found on the hairs aronnd the genitals, although they can occur in other areas of the body (e.g., eyelashes, beards, and axillae). Patients nsually complain of severe pruritus from papular lesions produced by the bite of the louse. Hypersensitivity to foreign material injected by the lice can produce macular swellings and occasionally can lead to secondary bacterial infections. ... 

Ecto-parasltes. Eggs of the louse, Menacanthus sp., and adult fowl mites, Ornithonyssus sylviarum were collected from adult birds and nests, respectively. This choice of ecto-parasite species was based on their potential for negative impact on nestling growth and survivorship (Moss and Camin, 1971 Powlesland, 1976). Logistical constraints determined which instar of each ecto-parasite was used. 

Eggs of the louse were found attached to the base of feathers on the heads and necks of adult birds (Boyd, 1951). These eggs were removed and placed in covered, humidified petrl dishes. Adult fowl mites were collected from infested nest boxes by placing a strip of paper amidst a swarm of mites, allowing the mites to board the paper, then depositing the mites and paper into a vial. Upon return to the laboratory, the mites were transferred to covered, humidified petri dishes. 

The incubation period ranges from I to 2 weeks, with an average of 12 days. Rickettsia Canada cannot be directly transmitted from human to human, but it is a bloodbome pathogen, and universal precautions should be practiced. Victims are infective for hce from the time in which the febrile (fever) illness is present and for 2 to 3 days after the body temperatme returns to normal. Infection remains in the louse for 2 to 6 days after biting the source, although it may occur quicker if the louse is crushed. Symptoms include headache, chills, fever, prostration, and general pains. On the 5th or 6th day, a macular eruption (unraised spots on the skin) occurs on the upper trunk and spreads to the entire body (except for the face, palms of the hands, and soles of the feet). The illness lasts for approximately 2 weeks. Without treatment, the fatahty rate is about 10 to 40%. Treatment involves antibiotic therapy with tetracyclines and chloramphenicol. 

DDT is an acronym for dichlorodiphenyl trichloroethane, but should be named more precisely as 2,2-bis(p-chlorophenyl)-l,l,l-trichloroethane (see Fig. 16.1 for its structure). A German chemist, Othmar Zeidler synthesized this compound in 1874 while he was pursuing his PhD. And it had remained as that, a new synthesized compound, for a quite while. Carl Muller of J. R. Geigy (a Swiss Pharmaceutical company, now Chiba-Geigy) discovered in his pursuit of insecticides that the compound synthesized by O. Zeidler was extremely toxic to houseflies. Numerous tests were conducted, and the compound DDT was found to be an excellent insecticide. Besides it is cheap to make. This was the time when the World War II was raging. DDT was then used to control lice on soldiers on the front. In earlier wars, more soldiers died of typhus (bom by louse) than by bullets. The WWII was really the first war in history where more soldiers died actually from bullets than the louse-bom disease, thanks to DDT. DDT was then considered to be a savior to control many kinds of harmful pests. C. Muller was awarded a Nobel prize in 1948. 

Using the rapid toxicity of phenothrin to adult body lice, we established a short-time bioassay method for head lice. Since KC99 of the susceptible body lice (after 3 hours treatment) was 54 mg/m (Table 1), we set a diagnostic phenothrin concentration at 100 mg/m filter paper. When a louse is alive at 100 mg/m, the louse is evaluated as a resistant. Since the KC of the susceptible body lice was 20 mg/m, a resistance-ratio (RR) of the louse alive at 100 mg/m ... 

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