Pick off

Abstumpfungsflache,/. (Cryst.) truncating face, abstiirzen, v.t. throw down, dump remove the lid from. — v.i. fall down fall off. absuchen, v.t. search, examine, scan pick off, clear off. 

When a temperate phage is mixed with sensitive indicator bacteria and plated as described above, the reaction at each focus of infection is generally a combination of lytic and lysogenic responses. Some bacteria will be lysed and produce phage, others will survive as lysogenic cells, and the plaque becomes visible as a partial area of clearing in the bacterial lawn. It is possible to pick off cells from the central areas of these plaques and demonstrate that they carry prophage. 

A Petri dish containing bacterial colonies is blotted with nitrocellulose paper. This transfers a large portion of each colony to the paper, which is saturated with a solution that lyses (breaks open) the cells. The DNA of the lysed colonies is denatured with alkali. The nitrocellulose paper is neutralized, washed, and the paper either baked in an oven or treated with ultraviolet light to immobilize the denatured DNA. The DNA on the paper is hybridized with the labeled probe of interest, and the excess label is washed off. The dried paper is exposed to photographic film and the film developed. The exposed spots on the film can be matched with the colonies on the master plate and colonies picked off for further study. 

PALS is based on the injection of positrons into investigated sample and measurement of their lifetimes before annihilation with the electrons in the sample. After entering the sample, positron thermalizes in very short time, approx. 10"12 s, and in process of diffusion it can either directly annihilate with an electron in the sample or form positronium (para-positronium, p-Ps or orto-positronium, o-Ps, with vacuum lifetimes of 125 ps and 142 ns, respectively) if available space permits. In the porous materials, such as zeolites or their gel precursors, ort/zo-positronium can be localized in the pore and have interactions with the electrons on the pore surface leading to annihilation in two gamma rays in pick-off process, with the lifetime which depends on the pore size. In the simple quantum mechanical model of spherical holes, developed by Tao and Eldrup [18,19], these pick-off lifetimes, up to approx. 10 ns, can be connected with the hole size by the relation ... 

These traps, (Fig. 6) and similar effects in the motion of holes and other charges through polymers, would eventually be correlated also with such structural probes as positron lifetimes in macromolecular solids. Extensive recent studies of positron lifetime are based on positronium decay. In this, the lifetime of o-positronium (bound positron-electron pair with total spin one) is reduced from about 140 nanoseconds to a few nanoseconds by "pick-off annihilation" in which some unpaired electron spins in the medium cause conversion quenching of orthopositronium to para-positronium. The speed of the t2 effect is supposed, among other things, to represent by pick-off annihilation the presence of defects in the crystalline lattice. In any case, what amounts to empty space between molecules can then be occupied by orthopositronium.(14,15,16) It is now found in linear polyethylene, by T. T. Wang and his co-workers of Bell Laboratories(17) that there is marked shift in positron lifetimes over the temperature range of 80°K to 300°K. For... 

Keeping plants growing well is the best defense against pests and diseases. Potbound plants in overcrowded pots, watered erratically, will be more prone to pests such as red spider mite and aphids, especially in hot and dry locations such as a sheltered patio. Deal with any problem as it arises check plants regularly and pick off pests or diseased shoots or leaves as you notice them. Remove sickly and badly infested plants. 

Pick off or prune out any leaves or shoots that are diseased or badly infested with pests if a whole plant has succumbed, then take it out of the greenhouse and dispose of it, and check its neighbors carefully. Biological controls (see p.97) are ideal for controlling many common glasshouse pests. For more tips, see p.250. 

From late spring onward, various moths and butterflies, such as the large cabbage white, may lay their eggs on brassica plants. The resulting caterpillars can be picked off by hand, if wasps have not removed them first. 

These hatch from eggs laid in clusters on the underside of leaves by the large cabbage white butterfly. If too numerous to pick off one by one, remove the whole leaf Wasps love caterpillars, and may remove them all for you. 

Pick off diseased fruit and foliage as seen. Powdery mildew symptoms on leaves are more likely in dry weather. Use a drip or soaker hose watering system to avoid wetting the foliage. 

What to do Pick off larvae and adults. Clear plant debris where beetles may overwinter. Pesticide Derris. 

What to do Examine plants regularly when the butterflies have been seen. Squash eggs, pick off caterpillars. 

Wbat to do Examine plants regularly. Pick off and destroy infected leaves. Control weeds, especially groundsel and thistle, as these can support the pest. 

What to do Where infestation is light pick off and destroy affected leaves. 

Larval pests that tunnel around feeding within leaves, creating characteristic maze patterns. They can be sguashed in their "mines" between finger and thumb, or leaves can be picked off. Damage tends to be more unsightly than harmful, except on leafy crops. 

What to do Pick off individual leaves as soon as the blotches are seen squash larvae within before putting the leaves on the compost pile. If you are only growing beets, there is no need to take... 

For it is not just external circumstances that are unique so also is each manager. Effectiveness is not something out there to be picked off the shelf and applied. It is the result of the interaction between, on the one hand, each manager s unique motivation and capabilities and, on the other, the opportunities and constraints present in the situation he or she is managing. 

Another part of the loop program ascertains how much solution is left in the pump. A voltage picked off a ten-turn potentiometer, which is coupled to the piston-drive screw with a timing belt, is fed to the analog-to-digital converter and is compared with the previously stored reading from the thumbwheel switch. 

PICK OFF A LEAF. REMOVE BLACK PAPER STRIPS. DIP IN BOILING WATER FOR A MOMENT TO KILL THE LEAF. THEN DROP IT INTO DENATURED ALCOHOL IN A CUSTARD CUP. PLACE CUSTARD CUP IN A POT OF BOILING WATER. AS ALCOHOL GETS HOT, IT EXTRACTS THE CHLOROPHYLL FROM THE LEAF. KEEP LEAF IN ALCOHOL UNTIL ALL CHLOROPHYLL IS OUT. 

Positron annihilation lifetime spectroscopy (PALS) provides a method for studying changes in free volume and defect concentration in polymers and other materials [1,2]. A positron can either annihilate as a free positron with an electron in the material or capture an electron from the material and form a bound state, called a positronium atom. Pnra-positroniums (p-Ps), in which the spins of the positron and the electron are anti-parallel, have a mean lifetime of 0.125 ns. Ortho-positroniums (o-Ps), in which the spins of the two particles are parallel, have a mean lifteime of 142 ns in vacuum. In polymers find other condensed matter, the lifetime of o-Ps is shortened to 1-5 ns because of pick-off of the positron by electrons of antiparallel spin in the surrounding medium. 

An important feature of o-Ps in polymers is that these particles tire preferentially formed or trapped in holes or regions of low electron density. The annihilation rate of o-Ps is proportional to the overlap of the positron and the pick-off electron wavefunctions and therefore the lifetime of o-Ps will depend on the size of the hole. The relative number of o-Ps pick-off annihilations is related to the number of suitable free volume sites in the polymer [3]. 

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