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Prestressed concrete pressure vessels (PCPVs) for nuclear reactors differ ssentially from other civil engineering structures, namely in relation to their extraordinary dimensions and stress conditions and different components (liner, penetration liners, etc.). These peculiarities involve a series of structural and constructional problems. The voluminous dimensions and high demands on the quality of prestressed concrete pressure vessels raise the questions of specifying the optimum concrete quality and of the concreting units to important aspects. The orderly placement and compaction of concrete underneath the almost horizontal base of the liner leads to special technical difficulties. Some solutions pertaining to these problems are discussed. PCPVs are highly prestressed structures. The difficulties with regard to horizontal prestressing are quite apparent, whereas the vertical prestressing presents no special problems. The wire-winding prestressing system already represents great progress in comparison with single anchored cables. However, it is not an optimum possibility. Further improvements in circumferential prestressing techniques are presented. Special problems of structural layout arise in the transition regions between the cylindrical wall and the end slabs at the inside of the vessel. In these zones of high stresses several components such as the liner cooling system, its feeding pipes, liner anchorages, and a concentrated reinforcement arrangement in three or four directions meet. Placement of these different components and reinforcement in such a way that their installation remains practicable and such that proper compaction of concrete in these zones can be assured is a difficult task. The difficulties could be considerably reduced by using concrete reinforced with steel micro-reinforcement. The same benefits would result for the other zones of high concentration of reinforcement and components (for example standpipe regions and penetration zones) by using this wire-reinforced concrete. The advantages of this new material for the construction of entire PCPVs are discussed. Further important structural problems are the anchorage of the steel liner especially at the transition zone between the cylindrical wall and the end slabs and the anchorages of penetration liners. Different structural design possibilities and their respective design criteria are discussed. Their advantages and disadvantages are pointed out.

A series of cyclic triaxial tests with varying amplitude was performed on samples of a sand in which they were subjected to stress reversal from compression to extension and vice versa. In the first place, the effect which the previous stress history in triaxial extension may have on the current deformation characteristics in triaxial compression, and vice versa was investigated. It was found that yielding of sand in reversing stress condition could occur independent of the previous stress history in an opposite direction, as long as the stress amplitude was made to stay within some limit. On the basis of the dircetional independency as above, together with the knowledge concerning the deformation characteristics under monotonous loads, an attempt was made of assessing how dilatancy and shear strains develop progressively during cyclic loading. This method proved to be applicable not only for stress-controlled but also for strain-controlled performance of sand.

A replicated comparison of reciprocal recurrent selection (rrs) based on crossbred performance and within strain-selection (wss) based on purebred performance was made in three diverse environments over ten generations for the improvement of a heterotic trait, 4-day virgin egg lay of Tribolium castaneum. A selection intensity of 20% based on performance in either an optimum (33°), a mild stress (38°), or a severe stress (28°) environment was applied uniformly. Periodically, the performance of each population was measured in all three environments to provide both direct and correlated responses.—Heritability of egg lay in the base population ranged from 0.36 ± 0.03 in optimum to 0.26 ± 0.03 in severe stress. Estimates of dominance effects assumed significant proportions in severe stress only. Genetic correlations for egg lay in diverse environments were large and positive (.6 to .8) .—Only in severe stress did the rrs response significantly exceed that for wss. Quadratic adjustments fitted t3 response curves revealed that small initial genetic gains under rrs were followed by significantly increasing rates of gain in late generations of selection. The reverse was true for wss. This and evidence from realized heritabilities and genetic correlations suggested that rrs had utilized both additive and dominance effects, but wss response was limited to additive effects.—These results agree with selection theory in demonstrating that purebred selection is mwe efficient than crossbred selection in utilizing additive gene effects. The latter method has merit when non-additive effects assume significant proportions, and this is the more probable case for severe stress conditions.

The effects of stress on state anxiety and on HR of male high school Ss were investigated using two psychomotor tasks. In the Stress Condition, Ss received negative feedback about performance; Ss in the Nonstress Condition were given rest intervals. Ss in the two conditions showed similar pretask, p> .05, A-State and HR measures. However, during the tasks the groups showed differing regression lines. The Nonstress Group maintained the same A-State level across the tasks with increased HR occurring as a result of the motor task. The Stress Group increased in A-State and HR measures. The two groups were significantly different, p

Four inbreds of pearl millet and their F1 hybrids, obtained by crossing the inbreds in all possible combinations, were grown in two seasons—the stress season and the non-stress season—to study whether there are any differences in the genotype environment interactions between the inbreds and their F1 hybrids. The mean chiasma frequency of the inbreds was lower and the variation of the mean chiasma frequency was more in the stress conditions than in the non-stress conditions. In both seasons the heterozygotes showed limited variation among their means, and larger mean chiasma frequencies when compared to the inbreds. The differences between the inbreds in their interaction with the seasons were significant. Different hybrids interacted with the seasons in a significantly different manner from each other. However, the differences between the inbreds as a group and hybrids as a group interacted with the environment in a large measure. When examined with the means, the significant differences between hybrids and inbreds in their interaction with the seasons showed that the hybrids were relatively stable over seasons as compared to the inbreds. The intercell variation within each plant was also examined as a variable to detect differences if any between genotypes, particularly to find out if the hybrids have a different type of variation as compared to the inbreds. The analysis revealed that the inbreds as a group are having larger means for this variable over hybrids. The hybrids have much less intercell variation within individual plants and nearly twice the buffering capacity of the inbreds. The hybrids and inbreds interacted similarly to the environment for the intercell variation. Diallel analysis carried out to study the genetic nature of heterosis for chiasma frequency revealed average overdominance for this character and the overdominance was shown to be at least partly due to non-allelic gene action.

The method of homogeneous deformation has been modified and applied to the calculation of second-order elastic constants for a class of noncentral interatomic potentials with the symmetry of Bravais lattices. The conditions of rotational invariance of the potential energy and the zero initial stress conditions were found and their validity was verified. For cubic symmetry a method was elaborated which applies to the noncentral interatomic potentials proposed byJohnson andWilson. The presented method of homogeneous deformation is compared with the original method ofFuchs and with the method of long waves in calculations of elastic constants.

Factors involved in physiological responses to water stress are discussed as they may relate to water-use efficiency by plants grown under conditions of drought. Evidence is presented that genotypic differences exist in plant responses to water stress. It is shown that previous exposure to stress conditions, or a natural hardening period, can markedly influence measured responses, such as photosynthesis and stomatal movement. Stage of growth at which the stress occurs also influences the response. A practical technique for measuring desiccation and heat tolerance demonstrates that genetically controlled tolerance factors can be selected for and used in plant breeding programs.

In order to study the role of brain biogenicamines in the regulation of ACTH secretion under basal and stress conditions, we examined changes in plasma corticosterone and hypothalamic CRF levels in ma

Two experiments were conducted to examine the relationship between stress level and learned helplessness in human subjects. Experiment I subjected subjects to loud or moderate noise in order to induce differential stress. Half of the subjects within each stress group were unable to escape from a series of noise bursts, whereas the other half could terminate each burst by manipulating appropriate switches. After the pretreatment series, the same noise was again delivered to subjects, all of whom could now escape or avoid noise by making an appropriate response on a shuttle box. Inescapable (helplessness) pretreatment interfered with escape learning in the second (test) phase of the study under both levels of stress. Experiment II was a partial replication of the first study using only loud noise. The interference effect during test trials was greater than in the first study. In addition to these findings, measures of a coronary-prone behavior pattern were related to differential susceptibility to the interference effect under both high stress and moderate stress conditions. These results were interpreted in terms of differing perceptions of threat imposed by lack of environmental control.

Growth and pigmentation of ‘Baccara’ rose buds were followed. Petal elongation mainly occurred during a short period of time after the flowering shoot had stopped elongating. Approximately 90% of the flower pigments were synthesized during a short period lasting from the time the bud was 75% to the time it was 100% of its diameter at opening time. Petal growth continued after this period so that the pigments in the petal were “diluted”. Heat stress applied to whole plants or to flower buds only, or a short duration of low light intensities caused “blueing” of the petals when these conditions prevailed during the period of maximum pigmentation. Stress conditions prior to this period or following it, had no effect. We suggest that stress conditions such as high temperature or low light intensities reduce the availability of sugars. When this occurs at the time of maximum pigment production, a fall in the level of pigment occurs, which results in the “blueing” of the petals.

In the habitat temperature, northern cold planktonic species seem more resistant to pressure than related southern warm species. Generally, a prolonged “hyperactivity phase” was recognized between moderate and high hyperbaric levels in most planktonic species. Descriptions of reactions of various planktonic species to increasing pressure are given with reference to stimulated activity (R1), onset of tetany (T), and inactivity (I). On the basis of LD50 levels, the 16 planktonic species show high, moderate, low or extremely low tolerance to one hour stress conditions of high hydrostatic pressure.

Previous investigations into cumulative damage fatigue under uniaxial stress are discussed in conjunction with the parameters relevant to the present experimental investigation. The results of two-level block programme tests on 2L65 aluminium alloy at four values of constant principal stress ratio and at several combinations of two different principal stress ratios are presented and discussed with reference to cumulative damage criteria developed for the case of uniaxial fatigue stress.

Most service failures in fatigue start on a free surface, as in many cases the most severe stress conditions exist there and are of a bi-axial stress nature, such as a drive shaft under combined bending and twisting. This particular case of multi-axial stress fatigue, because of its importance in design, has seen considerable investigation, although several aspects of the stress situation complicate the analysis of the test results with regard to the development of a general criterion of fatigue failure under multi-axial stress. The principal stress axes rotate with variations in the ratio of bending to twisting and the shaft is subjected to a stress gradient. Only the extreme portions of the shaft in the plane of bending are under the maximum bending stress, whereas the complete surface of the shaft is subjected to the maximum torsion stress.

The bottom chords and diagonal members of one of the 345-ft (105 m.) Petit type riveted through spans of Hardinge bridge were damaged by explosion during the war in 1971. As a result the span was out of shape and also was unfit for use. The span was repaired by temporarily securing the damaged truss from adjacent spans with the help of pin-connected link members. The damaged truss was jacked up from two steel barges specially strengthened from the purpose and the load was applied by pumping out water from (built-in) compartments in the barges. The job was of a challenging nature considering the unfavorable river condition and the short time available for restoration work. A computerized analysis of the damaged span was carried out to establish the stress condition of the various members of the damaged span.

SEVERAL workers have observed that reserpine has very little effect on the reproductive performance of chickens (Anderson and Smyth, 1959; Weiss, 1959; Carlson, 1959; Gilbreath et al., 1960). However, evidence was presented by Van Matre et al. (1957) and Parker (1960) which indicates that reserpine may alleviate decreases in egg production during stress conditions. In other avian classes it has been shown that this tranquilizer causes certain reproductive inhibitions. Reserpine administered to male pigeons by Khazan et al. (1960) caused a severe atrophy of the testes. Histological sections of the testes showed impaired spermatogenesis. Hewitt and Reynolds (1957) found that reserpine reduced egg production, fertility and hatchability in pheasant breeders. In growing turkeys aortic rupture has been successfully controlled with the use of reserpine (Couch, 1959; Carlson, 1959; Morrison, 1960; Barnett, 1960); however, the effects of the drug on the reproductive performance of this species have not been described. The …

The purpose of this experiment was to explore psychological mechanisms underlying the phenomenon of extremization of judgments (accentuation) under stress. Specifically the question was raised whether accentuation was due to some change of the internal representation of the objective scale (the personal reference scale, Upshaw, 1969). In the case of no indication for such a change a further analysis of accentuation concerning the nature of response shifts was intended. Four different degrees of stress were induced by varying levels of white noise stimulation. Induction of stress was monitored by measures of electrodermal and cardiac activity. Ss in each of the stress conditions rated statements on social issues for degree of socialist or communist attitude expressed. In part I of the experiment Ss were free to choose any bipolar scale comprising 2–13 categories. In part II they repeated their judgments on a 9-point bipolar scale. As degree of stress was not systematically related to scale selection in part I, there was no support for the hypothesis of a change of personal reference scale. A linear function between a general instability of the judgmental frame of reference and stress was found, however. Again an increasing tendency to accentuate under intermediate stress levels was observed. Under medium degree of stress an increased tendency to vary scales was also observed.

A rate of 0.3 failures per billion hours or less is desirable for memory components in large integrated arrays. This unusually stringent requirement complicates the determination of lifetime from accelerated aging studies. The value and limitations of step stress aging techniques are discussed in terms of experimental results obtained using plated wire memory arrays designed to withstand the high ambient temperatures required for accelerated aging. Step stress aging measurements alone are insufficient for confident lifetime prediction. Therefore, longer term measurements at lower temperatures must also be made to establish the validity of the lifetime extrapolations. It is essential to protect the plated wires against corrosion. Given proper protection a shelf life in the hundreds of years is forecast. The importance of duty cycle on lifetime in exercising the memory is discussed and the results of aging under extreme pulsed magnetic field stress conditions are reported. Criteria for wire selection, with long term stability in mind, are discussed.

1. The tensiometric method of investigation shows that the agreement between theoretical and experimental data is satisfactory. Consequently, the assumptions which have been made on designing idle drums with a flat disk* can be accepted: a) the drum is rigidly mounted on the shaft; b) the width of the belt is equal to the distance between the supporting disks; c) the part of the shell protruding beyond the limits of the supporting disks can be ignored. As a result, the interaction between the disk and the shell can be represented by the contour forces. The latter assumption is confirmed by an additional investigation of the stress condition of the protruding shell parts. 2. The discrepancy, noted for a number of points, between theoretical and experimental data is due to the error obtained by using this method if the level of stresses is not high and by averaging the strains over the length of a pickup. This is particularly noticeable for points with a high stress gradient. 3. The asymmetric and nonuniform application of load over the length of the drum on the side of the belt hardly distorts the picture of its stress condition.

Anhand der Ergebnisse einfacher Untersuchungen wird versucht, eine quantitative Aussage uber die Schadigung einiger modifizierter Polystyrol-Typen durch Trichlormonofluormethan (R 11) zu gewinnen. Weiterhin wird die Wirksamkeit verschiedener vorgeschlagener Schutzmasnahmen gegen die aggressive Einwirkung betrachtet. Bei kritischer Erorterung der Untersuchungsverfahren wird festgestellt, das trotz Abweichungen von den in der Praxis vorliegenden Beanspruchungsverhaltnissen bei Polyurethan-beschaumten Polystyrolen ein anschauliches Bild uber die Resistenz der modifizierten Polystyrole gegen R 11 entsteht, das insbesondere im Zusammenhang mit Wirtschaftlichkeits-Betrachtungen von Bedeutung sein kann. Investigations with regard to the effect of Trichlormonofluormethan (refrigerant R 11) on modified polystyrenes Due to the results of simple investigations it is being tried to obtain quantitative statement concerning the damage of some modified types of polystyrene caused by R 11. Furthermore the effectiveness of various protective measures proposed against the aggressive influence will be given an expert opinion. Discussing the testing procedures critically it is found that in spite of the deviations of stress conditions of polystyrenes foamed with polyurethane, as they exist in practice, the resistance of the modified polystyrenes against R 11 is quite evident what especially in connection with economy can be of importance.

Zoanthids of the genera Palythoa and Zoanthus regulate their populations of symbiotic zooxanthellae by expelling surplus algae produced under constant illumination. Zooxanthellae are also expelled when the polyps are placed under stress conditions such as salinities slightly higher than normal (35%.), temperatures of 30 °C, or under starvation. The algae are released in a polyp-like body formed by a concentrically rolled filament very similar to the mesenterial filaments of the animals and which contains extraordinary numbers of healthy-looking zooxanthellae. The significance of zooxanthellae for their hosts is specific and was observed to be greatest for Zoanthus sp. Aposymbiotic polyps of this species rapidly regressed and died under starvation.

Summary Small patches of abnormal tissue in the wood of European larch, termed xylem flecks, are described. They are particularly prevalent in the wood formed in the penultimate internode. Similar tissues were also seen in four other tree species. Fleck formation varied from year to year. Although xylem flecks resemble the tissue abnormalities associated with frost damage, it seems unlikely that their causation is climatic. All larch trees suffering from epidemic dieback contained xylem flecks and the possibility of an association with adelgid infestations is discussed. It is concluded that the flecks may have been a response to stress conditions, although a positive correlation in one tree between numbers of flecks and annual radial increment indicated a less simple explanation.

EPR studies of K2PbCu(NO2)6 as a function of temperature as well as under uniaxial stress conditions are reported. The lattice parameters in the two tetragonal phases below 280 K are measured, and changes with temperature are observed in the surfaces of a crystal viewed under a microscope. These results are explained in terms of a domain structure below 280 K which is related to a cooperative Jahn-Teller effect. Each domain consists of tetragonally compressed copper sites whose tetragonal axes are parallel. The g values are consistent with a tetragonally compressed environment for the Cu2+ ion, in which the states transforming as 3z2-r2 and x2-y2 are mixed by the vibrational motion of the ligands.

Summary.-2 groups (N = 144) of female undergraduate Ss from Auburn Universiq were divided into three subgroups with different drive levels according to scores on the Taylor MAS. A group having viewed a stressful film showed a significant depression in Digit Symbol scores when compared with a control group which observed a non-stressful film, regardless of MAS scores. Also, differences in gain scores across pre- and post-test trials were noted, with moderate MAS Ss showing significantly greater improvement regardless of stress condition. Interpretation of impaired Digit Symbol performance on the WAIS and the WISC as a response to situational stress is probably more conservative than predicting motivational levels based on a single 90-sec. trial. Performance on digit symbol tasks (D Sym) has been interpreted within the context of intelligence scales as a reflection of motivation and anxiety. Impaired performance has been attributed to heightened anxiety states (Wechsler, 1958) and to disinterest or low levels of motivation (Glasser & Zimmerman, 1967, p. 94). These interpretations appear partially consistent with the experimental literature regarding the effects of high anxiety and low drive level in causing a performance decrement on complex psychological tasks (Marks & Vestre, 1961; Johnson & Thomson, 1962). However, Taylor (1953) has questioned the exact relationship of drive and clinical anxiery, and this distinction has not been clearly delineated in the interpretations of D Sym performance. Studies in which learning is involved, such as Johnson and Thomson's (1962), suggest that an inverted U-shaped relationship is characteristic. Their results show that Ss having moderate motivational (drive) levels perform significantly better than those with either high or low motivational levels. Reviews of the literature on drive (Malrno, 1959; Campbell & Misanin, 1969) imply the usefulness of making a distinction between clinical anxiety, which may be induced through environmental stress, and drive, which is a relatively endogenous and enduring state of the organism. Consequently, both drive level and clinical anxiety (the latter defined as response to situational stress) might be presumed to influence performance on the D Sym task. This study was designed to measure performance on D Sym where the effects of: (a) readiness to react, i.e., anxiety level, (b) sustained drive level, or (c) a combination thereof could be delineated. PROCEDURE A total of 144 undergraduate women at Auburn University were selected from six classes in introductory psychology. Each class was randomly assigned

MEASUREMENTS of ascorbic acid in rat adrenals have been commonly employed as an indication of adrenal cortical function following treatments such as the imposition of stress conditions (Sayers et al., 1945), or the administration of adrenocorticotropin (Sayers et al., 1944, 1946), or crystalline steroid compounds, (Sayers and Sayers, 1947; Winter, 1950). In these studies the concentration of adrenal ascorbic acid rapidly diminished as the result of stress conditions or ACTH administration. Injection of cortisone or desoxycorticosterone 1 hour before exposure to stress prevented the depletion of adrenal ascorbic acid. On a milligram basis, cortisone was about four times as effective as desoxycorticosterone. However, daily administration of cortisone for six weeks resulted in a diminution of the concentration of ascorbic acid. Most of these studies involved whole gland analyses which can only give a picture of the average of the changes in the separate zones of the adrenal.

Synopsis The results of 230 consolidation tests on glacial lake clay are described in which the influences of direction and length of drainage, shape of sample, stress conditions of test, and scatter of results have been investigated. The experiments indicate why the rate of drainage under field conditions using sand drains can be three to four times faster than that predicted on the basis of present standard laboratory test procedure. On y décrit les résultats de 230 essais de consolidation sur argile de lac glaciaire avec investigation sur les influences de direction et de longueur de drainage, la forme de l'échantillon, les conditions d'essais des contraintes et dispersion des résultats. Les expériences indiquent pourquoi la vitesse de drainage dans les conditions, sur place, en employant des drainages de sable, peut ≖tre trois ou quatre fois plus grande que celle prédite sur la base de procédure actuelle d'essai type de laboratoire.

It is extremely difficult to take into account analytically all the possible c'ases both in prestressing and in the process of subsequent testing. In the following, an attempt has been made to explain analytically for a given (elevated) temperature the part played by prestressing in the changes in the characteristics of stress-rupture strength on the assumption that such changes are caused solely by the creep process. The difficulty of such a calculation is due to the fact that there is no proportionality between the number of defects of the crystal lattice and the actual change in the properties of the metal: a decisive part is played by the distribution of the defects and the stress conditions. In other words, it can be stated that any stress produces in a metal its dislocation structure, its grain-boundary structure and system of cracks [!]. In such calculations, extensive use has been made of the theory of linear summation of susceptibility to damage, the essence of which is expressed mathematically by the relationship n

In order to utilize the data on corrosion fatigue test to practical design, the correlations of corrosion fatigue strengths under various stress conditions are researched. In the paper, the reduction rate of fatigue strength due to corrosion, which we call corrosion effect βc, is compared under alternating bending and torsional stresses. Under the similar conditions of tests, βc in torsion is found always lower than in bending, and the relation of the both values is explained using authors' criterion on fatigue failures. Further, the effect βck of simultaneous notch and corrosion on fatigue strengths is studied by means of varying sharpness of circumferential notches of rotating bending test pieces. βck becomes less than βc×βk with sharpening of notches, and the progress is made clear.

Aseptic examination of blood and kidney material from three species of apparently healthy trout at two hatcheries showed that 12.5% of examined trout at one hatchery and 26.1% of trout at the other carried low numbers of bacteria. In addition, sera from these trout had agglutinins against some of the isolated bacteria and bacterial types found in trout were the same as those cultured from raceway water in which fish were raised. Although the presence of these bacteria does not constitute a disease state, the potential for an epizootic is present should trout be placed under stress conditions.

ABS>Two Nicotiana species and their species hybrid were subjected to varying dosages of gamma-irradiation for a period of two months. By the end of this period leaf abnormalities were evident in all dosages with the N. glauca parent, above 50 r per day in the hybrid and above 150 r per day in the N. langsdorffii parent. In general where leaf abnormalities occurred there was a concomitant increase in the free amino acid content of these leaves. Similarities, both morphological and physiological, to other organisms under stress conditions are discussed. (auth)

Experiments were made by Porter and Silber's method in N. A. Yudaev and Yu. A. Pankov's modification to establish the normal level of 17-hydroxycorticosteroids in the blood plasma of monkeys. The concentration of 17-hydroxycorticosteroids in male rhesus macaques was on the average 34±1.3 mg %, in females −44±1.2 mg %; in male and female hamadryads −41±1.5 mg % and 52±1.5 mg % respectively. Variable reaction of the adrenal cortex to intravenous injection of ACTH was found in different species of monkeys, in rhesus macaques the maximum increase in the amount of 17-hydroxycorticosteroids was registered one hour after the injection of the preparation, in hamadryads-in two hours. Nembutal anesthesis presents the development of the stress condition. It was found that the neuro-emotional strain in monkeys brings about a marked increase in the hormonal function of the adrenal cortex.

Proposals for representing damping under combined stress conditions in terms of an equivalent simple stress are examined. Some general requirements which such proposals must satisfy are developed and certain anomalies in previous proposals are pointed out. Alternative expressions for equivalent stress are suggested in forms which satisfy the general requirements subject to stated assumptions.

Full-scale laboratory experiments have been performed to determine the effectiveness of borehole strain rosette relief methods of measuring rock stress. The effect of the stress acting parallel to the borehole axis cannot be neglected when analysing the data. The stress distribution in the block of rock used in these experiments seems to conform closely to the three-dimensional photoelastic pattern for stresses around the flattened end of a borehole, determined by Galle and Wilhoit. It appears that independent information concerning the orientation of at least one of the principal stress directions is necessary before this type of borehole strain relief technique can be used. If the direction of one of the principal stresses is known, the effect of the stress acting parallel to the borehole axis on the measured strains taken into account, and the elastic moduli of the rock determined under stress conditions similar to those acting during the strain relief test, the method of strain rosette relief on the flattened face of a borehole gives a good estimate of the rock stress.

To clarify the effective factors for the crack propagation under varying load conditions, crack propagation is investigated using V-notched specimens and radial holed ones of 0.55% carbon steel and the following results are obtained. (1) The most important effective factor for the crack propagation under high-low type varying load condition is the essential increase of the stress at the crack tip for the opening of cracked surface caused by the repeated compressive plastic deformation. (2) In the case of steel specimens, there is no effect for the crack propagation under varying load condition caused by structural changing and it is also possible to estimate the crack propagation quantitatively considering the effect of crack opening. (3) It is also possible to estimate almost all the experimental results under varying load conditions qualitatively considering the effect of crack opening and existence of incubation period. (4) The effect of crack opening appears in the case of reversible stress condition but does not appear in the case of pulsating tension stress condition. This can be predicted by the calculation of the actual stress at the crack tip under varying load conditions.

We made experiments on the limit value pgs of pitting strength under various stress conditions in rolling contact of rollers with sliding motions. The endurance tests using various lubricants and with and without sliding motion, confirmed the question about the influence of lubricants on pitting strength. Moreover, we made tests on the influence of the methods of finishing roller surfaces on pitting strength.

Leaves of resistant and susceptible breeding lines of two closely related varieties of cabbage, 'Glory' and 'Globe,' showing internal tipbum were examined anatomically. Since both resistant and susceptible lnes developed tipburn, the type of injury rather than the amount was considered. Regardless of the degree of resistance, cellular disorders in the tipburned areas were the same. Early symptoms showed small gray areas at the lobes of the leaves. The outer parenchymatous cells of these areas remained normal. Some of the xylem vessels became occluded with a granular substance; surrounding cells, including the idioblasts, enlarged. The idioblasts, reported to contain the enzyme myrosin, contained a particulate substance. Some idioblasts hypertrophied and also divided resulting in the distribution of the particles to additional cells. The conditions causing tipburn also affected cell walls, causing thickening and the production of pectic warts between cells and on walls facing the intercellular spaces. As more xylem vessels became occluded, and as the number of idioblasts with particles increased, the cells at the periphery of the leaf collapsed. INTERNAL TIPBURN of cabbage has plagued growers for some time, but the exact cause of this disorder has not been established. Investigators agree that the cause is not a pathogen. As reviewed by Natti and Atkin (1962), conditions that have been reported as causes of tipburn include high and low amounts of certain elements, environmental conditions, and cultural practices such as time of planting and harvest. Walker, Edgington, and Nayudu (1961) showed that compared to normal heads, tipburned cabbage heads had a lower Ca content and that the amount of Ca in interior leaves was much lower than in the outer leaves, and leaf marginal tissue contained the least. High soil moisture and poor drainage contributed to the severity of the disorder. Maynard, Gersten, and Vernell (1965) studied the effect of levels of Ca on a resistant and a susceptible variety of cabbage and found that tipburn was related to low Ca content in the tissue. Under stress conditions the resistant variety was able to transport and accumulate more Ca than the susceptible one. They suggested that this possibly resulted from genetic variability. The selection of varieties resistant to tipbum has been Received for publication February 23, 1966. Published with the approval of the director of the Agricultural Experiment Station. reported and is in progress by Walker, Williams, and Pound (1965). Natti and Atkin (1962) were planning a breeding program designed to select F1 hybrids of cabbage that would be resistant to internal tipburn and other diseases. Considerable attention has been focused on the causes of internal tipburn, but the internal cellular responses have not been investigated. Consequently, this i.nvestigation was conducted to determine what abnormal cellular responses occurred. MATERIALS AND METHODS-In 1961 samples of marginal leaf tissue showing mild and severe tipburn symptoms were taken from eight fieldgrown mature heads of resistant and susceptible lines derived from the variety 'Glory.' In each of the following 3 years samples were taken from resistant and susceptible lines derived from the variety 'Globe.' The extent of internal tipburn was not considered in the resistant and susceptible varieties; only the anatomical responses were studied. The leaves were fixed in formalin-aceticalcohol or Craf (Nawaschin type III) solutions. Marginal areas of healthy tissue were used for comparison. The fixed leaves were dehydrated with n-butyl alcohol, infiltrated and embedded in Paraplast (Aloe Scientific, Division of Brunswick, St. Louis 3, Mo.). Sections were cut 10 ,u thick on a This content downloaded from 207.46.13.153 on Fri, 05 Aug 2016 05:44:13 UTC All use subject to http://about.jstor.org/terms

Estimation of the daily thyroxine I131 disappearance rate in cattle following sudden exposures to heat (38°C) and cold (1°C) conditions demonstrated that (a) the time required for thyroid function to decrease from normal values under heat stress was at least 60 hours, (b) the time for increased thyroid activity under cold required about 36 hours, and (c) the readjustment of the thyroid gland from hot and cold to the thermoneutral zone (18°C) required at least 108 hours. These findings indicated that the adjustment of cattle to a stress condition by alteration of thyroid activity is a relatively slow process. This provides the evidence that thyroid function is not involved in the early stages of acclimation, but it has a major role in the compensation stage of acclimation to the new environment.

Sand production, from a well completed in an incompetent formation without a metal screen, can be attributed to failure of the sand to form a stable arch around the wellbore or over a perforation. This study shows the usefulness of having a sand of high grain strength outside the perforations, and indicates that even a low-strength plastic can provide the restraint necessary to stabilize an arch. Introduction The petroleum industry has used both mechanical and chemical methods for controlling the production of sand from wells completed in unconsolidated formations. In developing sand control methods, mechanical studies have dealt mostly with the design of screens and slotted liners and the placement of gravel packs; chemical studies have dealt with the composition and performance of sand consolidation plastic systems, and techniques of applying them. Little attention has been paid in the literature to the mechanical process of failure of the sand structure around a wellbore and the factors that affect the stability of the formation. Our laboratory has conducted, in the past several years, both theoretical and experimental studies on the mechanics of sand failure. W.M. Ayers,1 in 1965, presented results of his theoretical studies combined with field experience. He discussed the stress field around a wellbore and its relation to the formation stability in terms of the shear strength properties of the sand. The work being reported here was a laboratory extension of Ayers' studies. It was conducted as a basic study of sand control and was carried out. in two phases:elucidation of the failure mechanisms of unconsolidated sands and of the mechanism of stabilization of sands by consolidating plastics, using triaxial strength tests; anda direct study of the arching behavior of sand, or the manner in which sand can form a stable structure spanning an opening. Background Shear Strength of Sand The study of the strength of bodies of granular materials generally falls within the realm of soil mechanics. A widely used criterion for shear failure of soils is the Mohr-Coulomb theory.2 This states that failure will occur when the major and minor principal stresses s1 and s3 combine to produce a critical and characteristic value of the obliquity, which is the ratio of shear stress t to normal stress s in the plane of shearing. The validity of this criterion, which ignores the intermediate principal stress s2, is supported by experimental evidence cited by Bishop.3 The shear strength of a sand may therefore be described in terms of a Mohr envelope and its slope a, the angle of shearing resistance. Shear Strength of Sand The study of the strength of bodies of granular materials generally falls within the realm of soil mechanics. A widely used criterion for shear failure of soils is the Mohr-Coulomb theory.2 This states that failure will occur when the major and minor principal stresses s1 and s3 combine to produce a critical and characteristic value of the obliquity, which is the ratio of shear stress t to normal stress s in the plane of shearing. The validity of this criterion, which ignores the intermediate principal stress s2, is supported by experimental evidence cited by Bishop.3 The shear strength of a sand may therefore be described in terms of a Mohr envelope and its slope a, the angle of shearing resistance.

For the first time in this country's construction practice a great number of technical investigations were carried out on the Krasnoyarsk hydroelectric powerplant construction site in the years from 1963 to 1966, connected with developing and introducting new techniques for placing concrete in high lifts.* It was found in these full-scale tests that the required temperature regimen and stress conditions in the concrete could be controlled in lifts up to 12-m high.

In previous papers [1–4] the author has developed the theory of rock pressure on ring-shaped walls of circular section for the conditions when: 1. (a) around the shaft axis rotation symmetrical plane stresses have an influence 2. (b) in the surroundings of a roadway or circular cross section triaxial, but rotating symmetrically, geostatic stresses have an influence. This paper describes the calculation of rock pressure on ring-shaped walls of circular section for the conditions when: 1. (c) the geostatic stress condition around the shaft is rotational symmetrically but also a vertical stress appears. 2. (d) the geostatic stresses around the roadway of circular cross section are not rotation symmetrical. The origins of this paper are to be found in the following basic theses: 1. (1) The unsupported rock mantle of the roadway of circular cross section extends at right angles to the longitudinal axis of the roadway towards the inner space of the roadway when it becomes plastic under the influence of geostatic stresses. This displacement is residual in that it surpasses the degree of elastic displacement. 2. (2) The onset of plastic deformation around the roadway can be hindered by rotation symmetrical force systems acting from within and directed outwards, superposed on the roadway mantle. When the distortion potential of the resultant stresses of the geostatic stresses and the stresses of the superposed force systems are equal, even to the rock distortion (deformation) potential, then movement of the rock mantle ceases. Graphs showing the basic properties of rocks and metals under compressive loading are enclosed in the paper, which summarizes the general deduction of the distortion (deformation) potential. The relations by which to calculate the limit of the plastic and elastic ranges on the roadway edge, and the rock pressure on the linings of shafts and roadways of circular section, are described. A ring support built into the excavated cross-sectional area changes the original rock pressure distribution. The paper describes a test performed in the Ring Support Testing Laboratory of the Hungarian Mining Research Institute, based on which an approximate relation may be found for calculating the change in rock pressure. Finally some practical examples of the industrial application of theoretical results are included.

Laboratory tests conducted by the author in the Rock Mechanics Section of the Hungarian Mining Research Institute have shown that rocks display ranges of elastic and plastic behaviour. A measuring process has been developed to establish the limits of plastic yield in rocks. From the results of these experiments rocks are considered as structural materials and it is shown that the stress condition in the earth's crust differs substantially from that commonly supposed. The paper includes theoretical treatments to solve some problems of mining. These include the determination of the rock pressure on ring-shaped tunnel walls and the calculation of dimensions for the walls. Both these methods have been successfully introduced in practice.

The current theories dealing with the mechanics of joint development are discussed critically. An analysis of the stress conditions which can exist in competent rocks in the crust is presented. The conclusion is reached that “Master” and “Regional” Joints can be, generically, either “tensional” or “shear” structures. They are, however, post-tectonic phenomena which develop as a result of uplift. Joints form a part of “movement pictures” because their orientation is determined by residual stresses. Reasons are given which indicate that the mechanism described is generally applicable to joint development in folded sediments, igneous rocks, and also to incompetent material.