Weaker Link Research Articles

Steel‐to‐Steel Connections with Adhesives

The feasibility of connecting steel‐to‐steel with adhesives is examined. Specifically, the mechanical properties of structural adhesives, fabrication procedures, and properties of bonds are discussed. The mechanical properties of structural adhesives depend on temperature. In general, adhesives behave viscously at room temperature. Above certain stress levels, tertiary creep and creep rupture occur. An important adhesive material property is the diffusion coefficient, which controls the rate at which water enters an adhesive. The static strength of a bond depends on the cohesive strength of the adhesive and on the adhesion between the steel and the adhesive. If adhesion is the weaker link, then rupture is characterized by interfacial debonding. If adhesion is the stronger link, cohesive failure occurs within the adhesive, often due to tertiary creep. Creep rupture data for bonds made with two adhesives are given. Durability data on bonds stressed in 1984 are also presented. Studies on the fatigue and fracture toughness of bonds are briefly discussed. S‐N curves for bonds made with a modified acrylic adhesive are presented.

Impulsiveness and antisocial behaviour in children

An Impulsiveness inventory was completed by 118 boys and 309 girls from London comprehensive schools. Of these, 101 boys and 306 girls also completed the Eysenck Junior Personality Questionnaire and an Antisocial Behaviour Scale. Intercorrelations of the scores suggest that there is a strong link between antisocial behaviour in children and impulsiveness, as well as psychoticism or toughmindedness, and a weaker link with venturesomeness, extraversion and lack of empathy. Neuroticism was only slightly implicated for girls and hardly at all for boys.

Functional properties of the descending medial longitudinal fasciculus

The functional importance of the medial longitudinal fasciculus (MLF) in carrying vestibular impulses into the spinal cord has been studied in cats. The amplitude, duration, and latency of the gross motor responses evoked by vestibular stimulation and recorded from cervical and lumbar levels do not show any significant or persistent changes after a selective bilateral disconnection of the descending MLF. Thus, in evaluating the hierarchical importance of the three descending vestibulofugal pathways it becomes obvious that the MLF offers a much weaker link than the connections represented by the vestibulospinal and reticulospinal tracts. By sectioning all pathways other than the MLF in the brain stem at the rerebellopontine angle this tract could be investigated in anatomical isolation from adjacent vestibular connections. Vestibular stimulation applied to this “MLF animal” preparation evoked motor responses which could be recorded as far down as mid-thoracic levels. No sign of activity was ever recorded from lumbosacral levels. Judged by the response, the MLF seems to have a homogenous fiber spectrum, and the mean speed of conduction of the neurons is about 63 m/sec. Single MLF axon recordings demonstrated that the discharge frequency in response to vestibular stimulation may reach values that are more than twice the value of ventral root alpha-fiber discharge in response to identical stimulation, and that the synaptic transmission across the vestibular nuclei occurs with a considerable safety factor. Excitatory and inhibitory postsynaptic potentials evoked by vestibular activity conducted in the MLF have been recorded intracellularly from flexor and extensor motoneurons at cervical levels, but the relative amounts of excitatory or inhibitory action on a test motoneuron are variable. Pure EPSP or IPSP can be recorded but the majority of motoneurons showed EPSP; the long latencies of each were approximately the same and indicate that spinal interneurons are involved in the transmission. These depolarizing and hyperpolarizing effects could be recorded in a random fashion from flexor and extensor neurons, as identified by antidromic stimulation, but no consistent sign of reciprocity was obtained when recording from neurons with antagonistic function.

Chain Store Distribution vs. Independent Wholesaling

ally belonged to the regular or independent wholesaler. A century ago the wholesaler was the dominant factor in merchandise distribution. Manufacturers were much smaller generally than they are today, hence they required the sort of service the wholesaler had to offer. Retailers too were normally independent, small-scale operators who relied heavily on the wholesaler for the merchandise they sold. Direct selling or buying as we think of it today was practically nonexistent for most manufactured commodities. All imported commodities flowed through wholesalers' hands and most exports were sold through wholesale exporters. In the rural areas and in communities adjacent to agricultural activity, retail merchants traded directly with farmers, as they continue to do in many parts of the country. Today the wholesaler remains one of the most important links in the chain of distribution, but a far weaker link than was true in the past. His position has been challenged and weakened from two directions. (I) The expansion of manufacturing into gigantic mass-producing industries generated pressure for ever increasing sales volume. The wholesaler was unwilling or unable to devote the attention to any one producer's lines which the latter deemed necessary. Hence, manufacturers sought to shortcircuit or side step the wholesaler by various means of direct selling. These means run all the way from advertising and sales promotion directed at consumers and retailers to the establishment of elaborate branch wholesale houses throughout the nation. (2) The development of large-scale retailing in the form of mail order houses, department stores, and chain systems, especially since the beginning of the century, has generated pressure for direct purchasing in the hopes of securing lower prices. It is with the last of these, the chain stores, and their competitive impact on the wholesaler that this article is concerned.

Fire prevention in state hospitals

Although much space has been devoted herein to the physical aspects of fire prevention in a hospital for mental patients, attention is drawn again, in closing, to the administrative features of an effective program for guarding against this hazard. A knowledge of what to do, as well as when and how to do it, is of course of primary importance. The human factor, however, is large in the operation of an institution, and many strong links in the chain of a fire prevention program will be of no avail if a weaker link fails to do its work. For this reason, the matter of personnel instruction must be emphasized; this is on the assumption that there will be a genuine feeling of responsibility among all those employees and staff members who form the line of defense against fire. There must be no haphazard management of responsibilities; each person must know his particular duty, and must have the initiative to carry out his part of the work. In this phase of institution operation, no less than in any other, there should be no tendency to shift responsibilities, for it is in the process of shifting that one seemingly insignificant detail may be overlooked, with resulting disaster.