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The probability of failure of California Delta levees was estimated using simple statistical procedures, based heavily on empirical data. Fortyfour islands were included in the study, and it was found that the probability of failure was strongly linked to the thickness of peat beneath the levees. When the islands were grouped according to peat thickness, it was found that sufficient historical levee failure data was available to estimate the average probability of failure for all the islands in a given peat thickness group. The relative probabilities of failure for the islands within a group were then estimated using slope stability analysis and simple statistical methods. For each island a Factor of Safety Index FSI was computed for ranges in water level outside the levee and a range of values of the strength parameter, ϕ′.The water level was statistically characterized by the Gumbel Distribution and ϕ′by a Normal Distribution. The probability that the FSI would fall below some critical value was used to rank the probabilities of failure for islands within a peat thickness group.

A series of oedometer tests are used to provide data for a quantitative prediction of soil collapse. A full scale field test is conducted to provide a benchmark for comparison with laboratory test results and predictions. It is then found that the amount of field collapse can be accurately predicted using the procedure prescribed herein, provided that the extent of wetting is known.

A laboratory investigation of the thermomechanical response of deep ocean sediments has been performed. The study encompasses the range of thermal loadings expected for the emplacement of a canister of radioactive waste approximately 30 m below the seafloor in deep ocean waters. The experimental program included mechanical and thermal consolidation, undrained triaxial compressive strength and constant stress level creep tests on seafloor sediments over a temperature range of 4–200 °C.

An evaluation of water sources and extent of wetting at a collapsible soil site is presented. The field and laboratory data were collected after distress of an existing structure was observed. The underlying soils at the site were highly variable in fines content, density, and degree of saturation. Because of the high variability of soil properties, suction contours were developed for the site to evaluate the extent of soil wetting. A relationship between soil suction and basic soil parameters was developed for use in constructing these contours. The depth of wetting obtained using the suction contours was consistent with other data at the site, including quantity of water introduced and standard penetration test results. Laboratory collapse curves were used to estimate the settlement at the site for the depth of wetting inferred from the suction contours. The computed settlements, taking into consideration partial wetting effect, were consistent with observed settlements of the structure.

Collapsible soils, whether engineered or naturally occurring, may exist in seismic zones. This study focuses on the evaluation of the shear strength and volume change of collapsible soils subjected to static and dynamic shear loading under a range of confining pressures and wetting conditions which ranged from “as-prepared” to soaked to backpressure saturated. Tests are conducted on reconstituted samples simulating compacted engineered fill and natural density samples. Prior to shear loading (whether static or dynamic), triaxial response-to-wetting tests are performed under soaked or backpressure saturated conditions. Volumetric strains are measured using an image processing technique and the results are compared with those obtained from a one-dimensional test. A series of consolidated-undrained triaxial tests are performed to evaluate undrained shear strength after wetting, and correlations between undrained shear strength and degree of saturation are obtained. A series of stress-controlled cyclic triaxial tests are performed to evaluate the dynamic shear strength after wetting. Trends for the development of axial strain with the progression of loading cycles are dependent on wetting conditions (degree of saturation/matric suction). Furthermore, the cyclic stress ratio at failure is correlated with degree of saturation and charts for the evaluation of dynamic settlement of the test soils are developed. Finally, post-cyclic static shear strengths are determined by conducting a series of undrained static shear triaxial tests on selected samples following the application of cyclic load.

There is lack of agreement on laboratory procedures that should be used to measure swell pressure. In this study, effects of apparatus compressibility and applied initial net normal stress on measured swell pressure were revisited, with emphasis on undisturbed specimens. Samples covering a wide range of properties were collected from Texas and Arizona, and effects were explored by examination for consistency of trends in behavior for several “companion” sets of undisturbed specimens. Failure to account for apparatus compressibility results in unintended swell of the specimen, reducing the constant volume swell pressure by as much as half for specimens of this study. Applied initial net normal stress level also affects measured swell pressure. For specimens of this study, swell pressures measured at low initial net normal stress (token load) were found to be about 40%, on average, of swell pressures measured for specimens loaded initially equivalent to field overburden stress. This difference is believed to be primarily due to initial specimen compression. Commonly adopted sampling disturbance corrections to constant volume tests conducted at initial light confining stress (∼ 1–7 kPa) were investigated, and found to give inconsistent values of swell pressure. Comparisons of constant volume to load-back swell pressure are also presented. Findings suggest that application of an initial confining stress level corresponding to field conditions and application of apparatus compressibility corrections as the swell pressure develops are key to the consistent measurement of constant volume swell pressure, and that measured swell pressures from constant volume tests, when carefully performed, are more consistent than swell pressures estimated using methods to account for sampling disturbance.

Equilibrium moisture beneath highway pavements is critical to pavement design because it directly affects the strength and stiffness of pavement systems. Moisture is related to soil suction by means of the soil water characteristic curve (SWCC). Previous research has indicated a correlation of suction with Thornthwaite's moisture index and soil type; however, these suction correlations exhibit large variability. Under NCHRP Project 9-23, Environmental Effects in Pavement Mix and Structural Design, sponsored by FHWA, soil samples were collected from beneath 30 pavement sections throughout the United States. The SWCCs and index properties of collected samples were measured at Arizona State University. The in situ degree of saturation was obtained and the corresponding in situ soil suction was found from measured SWCCs. On the basis of the field and laboratory data, two models were developed to predict equilibrium suction under pavements: one for granular nonplastic materials and another for fine-grained plastic materials. These models were adopted in the new AASHTO Mechanistic-Empirical Pavement Design Guide because they exhibited good results, with variability within acceptable limits. Model development is presented.

Equilibrium moisture beneath highway pavements is critical to pavement design because it directly affects the strength and stiffness of pavement systems. Moisture is related to soil suction by means of the soil water characteristic curve (SWCC). Previous research has indicated a correlation of suction with Thornthwaite's moisture index and soil type; however, these suction correlations exhibit large variability. Under NCHRP Project 9-23, Environmental Effects in Pavement Mix and Structural Design, sponsored by FHWA, soil samples were collected from beneath 30 pavement sections throughout the United States. The SWCCs and index properties of collected samples were measured at Arizona State University. The in situ degree of saturation was obtained and the corresponding in situ soil suction was found from measured SWCCs. On the basis of the field and laboratory data, two models were developed to predict equilibrium suction under pavements: one for granular non-plastic materials and another for fine-grained plastic materials. These models were adopted in the new AASHTO Mechanistic–Empirical Pavement Design Guidebecause they exhibited good results, with variability within acceptable limits. Model development is presented.

A new oedometer device for SWCC determination has been evaluated by testing a wide range of soil types, and recommendations for best practices for use of this device have been made. The new device allows application and control of the net normal stress, σ−ua, in addition to the matric suction, ua−uw. Thus it can be used to simulate a range of overburden stresses and various other stress states of interest. It also allows the measurement of specimen volume change and the use of a single specimen for determination of the SWCC. The evaluation includes issues of temperature control, air diffusion through high air entry ceramic disks, and study of potential sources of error in water content determination for the SWCC. It is concluded that the new oedometer device can be used to obtain an accurate SWCC for a single specimen up to 1500kPa. General recommendations for appropriate use of the equipment and corrections to SWCC data obtained using axis translation pressure plate-type devices are made.

It is well documented that environmental effects play a significant role in characterizing material properties, which in turn affect pavement performance. Studies under the Strategic Highway Research Program (SHRP) were carried out on the age-hardening characteristics of asphalt binders and mixes. As a result, laboratory procedures to simulate the field hardening of asphalt binders and mixes, AASHTO Provisional Protocols PP1–98 and PP2–99, were developed. The approaches followed in these procedures are of great value for the ongoing research on pavement aging; however, due to limited resources and time constraints under the SHRP program, these provisional procedures have certain limitations. A research study, NCHRP Project 9–23, was initiated to overcome these limitations and enhance the predictive capabilities of these protocols. The current research paper is a part of NCHRP 9–23, which deals with the PP1–98 protocol. Binders and field cores were obtained from long-term pavement performance and other sites across the United States. Original, laboratory-aged, and field-aged binders were characterized through dynamic shear rheometer testing. The existing protocol was verified; on the basis of the findings, the protocol was improved to include the effect of field aging conditions and mix properties. The developed model was calibrated and validated with field data. Parametric analysis was performed on the final model to ascertain the practicality of the output. On the basis of those findings, a recommended provisional protocol was developed. The recommendations apply only for conventional, nonmodified binders.

It is well documented that environmental effects play a significant role in characterizing material properties, which in turn affect pavement performance. Studies under the Strategic Highway Research Program (SHRP) were carried out on the age-hardening characteristics of asphalt binders and mixes. As a result, laboratory procedures to simulate the field hardening of asphalt binders and mixes, AASHTO Provisional Protocols PP1–98 and PP2–99, were developed. The approaches followed in these procedures are of great value for the ongoing research on pavement aging; however, due to limited resources and time constraints under the SHRP program, these provisional procedures have certain limitations. A research study, NCHRP Project 9–23, was initiated to overcome these limitations and enhance the predictive capabilities of these protocols. The current research paper is a part of NCHRP 9–23, which deals with the PP1–98 protocol. Binders and field cores were obtained from long-term pavement performance and other sites across the United States. Original, laboratory-aged, and field-aged binders were characterized through dynamic shear rheometer testing. The existing protocol was verified; on the basis of the findings, the protocol was improved to include the effect of field aging conditions and mix properties. The developed model was calibrated and validated with field data. Parametric analysis was performed on the final model to ascertain the practicality of the output. On the basis of those findings, a recommended provisional protocol was developed. The recommendations apply only for conventional, nonmodified binders.

Conditions in arid and semi-arid climates favor the formation of the most problematic collapsible soils. The mechanisms that account for almost all naturally occurring collapsible soil deposits are debris flows, rapid alluvial depositions, and wind-blown deposits (loess). Collapsible soils are moisture sensitive in that increase in moisture content is the primary triggering mechanism for the volume reduction of these soils. One result of urbanization in arid regions is an increase in soil moisture content. Therefore, the impact of development-induced changes in surface and groundwater regimes on the engineering performance of moisture sensitive arid soils, including collapsible soils, becomes a critical issue for continued sustainable population expansion into arid regions. In practicing collapsible soils engineering, geotechnical engineers are faced with (1) identification and characterization of collapsible soil sites, (2) estimation of the extent and degree of wetting, (3) estimation of collapse strains and collapse settlements, and (4) selection of design/mitigation alternatives. Estimation of the extent and degree of wetting is the most difficult of these tasks, followed by selection of the best mitigation alternative.

Many state departments of transportation (DOTs) are beginning to use a larger percentage of drilled shafts for their deep foundations. Therefore, a clear understanding of current design methodology and specifications is important. The three most common design methods in use today are the group reduction factor, the p-multiplier method, and the modulus of subgrade reaction multiplier. A brief discussion of each method is presented. Telephone interviews were conducted with state DOTs to determine their current design procedure for groups of laterally loaded drilled shafts. Responses were obtained from all 50 states. Additional interviews were conducted with several well-known researchers in the field of deep foundations to determine what procedure they recommend. From these interviews it was clear that there is no uniformity in design methods or even in interpretation of the AASHTO recommendations for laterally loaded drilled shaft groups. The different interpretations of the AASHTO recommendations may be due to wording used in the AASHTO specifications, namely, the “ratio of lateral resistance of shaft in group to single shaft.” It is somewhat unclear as to whether this wording refers to the single-pile capacity or to the soil resistance. To understand the intended method of application of these factors, a historical search of the literature was conducted. It is clear that the source cited in the AASHTO specifications recommended using the reduction factors to reduce the modulus of subgrade reaction.

Increased water content of subgrade soils can lead to degradation of their quality and result in pavement distress. Pavement performance depends on the modulus of the compacted unsaturated subgrade soil as well as that of the underlying natural soil deposits. The soil modulus is a strong function of water content; therefore, changes in water content over the life of the pavement must be understood. In this study, it has been found that for a relatively near-surface groundwater table, significant potential exists for capillary rise into subgrade soils. For fine-grained soils in particular, the height of this capillary rise can be quite substantial. Results from capillary rise column experiments have shown that soils wetted above the groundwater table through capillary rise remain at a degree of saturation averaging about 60 percent. It has also been found that soil suction within this capillary zone must be determined through the use of soil water characteristic curves or direct measurement. The conventional assumption that negative pore water pressures can be estimated by backward extrapolation above the groundwater table of a line of slope γw is only appropriate in a very thin region above the groundwater table, where soils are wetted to a degree of saturation of 85 percent or more.

Increased water content of subgrade soils can lead to degradation of their quality and result in pavement distress. Pavement performance depends on the modulus of the compacted unsaturated subgrade soil as well as that of the underlying natural soil deposits. The soil modulus is a strong function of water content; therefore, changes in water content over the life of the pavement must be understood. In this study, it has been found that for a relatively near-surface groundwater table, significant potential exists for capillary rise into subgrade soils. For fine-grained soils in particular, the height of this capillary rise can be quite substantial. Results from capillary rise column experiments have shown that soils wetted above the groundwater table through capillary rise remain at a degree of saturation averaging about 60 percent. It has also been found that soil suction within this capillary zone must be determined through the use of soil water characteristic curves or direct measurement. The conventional assumption that negative pore water pressures can be estimated by backward extrapolation above the groundwater table of a line of slope γwis only appropriate in a very thin region above the groundwater table, where soils are wetted to a degree of saturation of 85 percent or more.

Many state departments of transportation (DOTs) are beginning to use a larger percentage of drilled shafts for their deep foundations. Therefore, a clear understanding of current design methodology and specifications is important. The three most common design methods in use today are the group reduction factor, the p-multiplier method, and the modulus of subgrade reaction multiplier. A brief discussion of each method is presented. Telephone interviews were conducted with state DOTs to determine their current design procedure for groups of laterally loaded drilled shafts. Responses were obtained from all 50 states. Additional interviews were conducted with several well-known researchers in the field of deep foundations to determine what procedure they recommend. From these interviews it was clear that there is no uniformity in design methods or even in interpretation of the AASHTO recommendations for laterally loaded drilled shaft groups. The different interpretations of the AASHTO recommendations may be due to wording used in the AASHTO specifications, namely, the "ratio of lateral resistance of shaft in group to single shaft." It is somewhat unclear as to whether this wording refers to the single-pile capacity or to the soil resistance. To understand the intended method of application of these factors, a historical search of the literature was conducted. It is clear that the source cited in the AASHTO specifications recommended using the reduction factors to reduce the modulus of subgrade reaction.

The study models of a group of adult Sri Lankan patients with clefts of the secondary palate were investigated. Tooth-size and arch-dimension comparisons were made with a comparable control group. Significant differences were found between the cleft and control groups in tooth sizes, chord lengths, and arch widths. The cleft group dimensions were generally smaller than those of the control group. Overjets were larger in the cleft group.

Gravelly subgrade materials are frequently evaluated on the basis of laboratory testing on material passing the number 4 sieve size due to difficulties in obtaining representative samples and because laboratory testing of soils containing rock is more difficult or expensive. When the large aggregate is not considered in the evaluation process, it is quite possible to discard a material as being inappropriate as subgrade material when in fact it may be quite suitable. For example, the presence of rock or gravel materials may have an ameliorating effect for clayey soils having potential for expansion upon wetting. The effect of large aggregate on the moisture sensitivity of subgrade materials are reviewed. It is more difficult to establish field specifications and to conduct field inspections for compaction of subgrades containing large aggregate. The potential pitfalls in obtaining the desired relative compaction in the field are discussed. The various comonly used techniques in writing field specifications for compaction of materials containing rock or gravel are reviewed.

The maxillary arch-form of 41 Sri Lankan adults with unoperated complete unilateral cleft lip and palate (8 female and 33 male) were compared to a control group of 100 normal Sri Lankan adults (45 female and 55 male). The teeth In the cleft group were smaller than their equivalents in the control group, the most marked difference being found in the central and lateral inclsors. Arch widths of the cleft groups were reduced, more anteriorly than posteriorly, resulting in more V-shaped arches. No differences were found in the arch length or chord lengths between the groups. Crossbites occurred in 19.5 percent of the cleft group as compared to none of the controls. The overjet was greater in the cleft group than in the controls. A higher percentage of missing teeth was recorded in the cleft group.

This paper investigates the effects of surgery on facial growth and morphology in Sri Lankan males with unilateral cleft lip and palate who were over 13 years of age at the time of study with cephalometry and dental study models. Three separate subgroups were analyzed: those who had totally unrepaired cleft lip and palate, those who received lip repair In Infancy but not palatal repair, and those who had lip and palate repair in infancy. Twenty-three healthy noncleft Sri Lankan males over 13 years formed a control group from the same racial background. The results show that subjects who had no surgery had a potential for normal maxillary growth. Subjects who have had lip repair in early infancy show relatively normal maxillary growth, but maxillary hypoplasia is common when the palate has also been repaired early.

A detailed comparison of moduli measured in the laboratory by resilient modulus testing with moduli measured in the field by falling weight deflec‐tometer (FWD) testing is made. This comparison includes an analysis of whether good agreement between lab and field values should be expected as well as an assessment of relative quality of the results and relative testing costs. Good agreement between lab and field measured moduli should not be expected when following the usual practice of sampling and testing only the top 1 or 2 ft (0.3 or 0.6 m) of the subgrade. Agreement is not to be expected because different volumes of the material are being tested in the laboratory compared to field testing by FWD. Because different volumes of material are tested, heterogeneity in any layer contributes to different measured moduli by lab and field testing. It is also concluded that the cost of determining moduli by laboratory resilent modulus testing is typically 60–80 times greater than the cost of an equivalent field testing program with the FWD. When the added costs of traffic control during sampling and project delays are included, the cost ratio may exceed 100. Furthermore, the moduli from field FWD testing are typically of higher quality and more appropriate for mechanistic pavement design than lab‐measured moduli. This conclusion arises from the fact that it is very difficult, if not impossible, to erase completely the effects of sample disturbance on lab‐measured moduli. In addition, when moduli are back‐calculated from FWD testing, a proper weighting factor is automatically applied to all zones contributing to deformations, it is also possible to take advantage of compensating errors in back‐calculated moduli.

Zusammenfassung In § 1 und 2 wird gezeigt, daß die Temperaturabhängigkeit der Leitfähigkeit eine unmittelbare Folgerung aus der Wellenauffassung der Elektronen ist. Zu diesem Zwecke wird die Interferenz der Elektronenwellen untersucht. In § 3 ist die für die weiteren Rechnungen nötige Annahme über den Potentialverlauf eines Ions dargestellt. § 4 und 5 geben die Berechnung der Leitfähigkeit selbst für festen und flüssigen Zustand. Die Druckabhängigkeit der Leitfähigkeit wird in § 6 auf die elastischen Konstanten des Metalls zurückgeführt. In § 7 wird eine einfache qualitative Erklärung der Matthiessenschen Eegel gegeben. In § 8 wird die Richtungsabhängigkeit der Leitfähigkeit in Kristallen abgeleitet. § 9 und 10 endlich behandeln die Thermokraft.

Zusammenfassung Es wird gezeigt, daß die Sommerfeldsche Behandlung des Richardson-Effekts die beobachtete Elektronemission kalter Metalle erklären kann unter der Annahme, daß das äußere Feld die Ablösungsarbeit der Elektronen vermindert.

In 1893 Ernst Fuchs1 first reported as an entity a group of 12 cases, 8 of which he considered typical. He coined the term retinitis circinata to describe them, for the retinal picture strongly brought to mind the skin lesion herpes circinatus (tinea circinata).These cases occurred predominantly in elderly women and involved one or both eyes in a chronic disease process. All showed a gray or yellow-gray macular discoloration encircled by a zone of small discrete or larger coalescing white spots, with an intervening relatively normal retinal area. The central discolored area was small at first but later became disc-sized or somewhat larger. It had no sharp boundary and at times appeared slightly raised. There was minimal or no pigment proliferation seen in these cases. The incomplete ring of white faintly glistening spots was always deep to retinal vessels. Ageing spots became dirty white. The central changes persisted

This section will be devoted to both macular and extramacular circinate lesions as seen in venous obstruction, diabetic retinopathy, Coats' disease, Leber's disease (multiple miliary aneurysms with retinal degeneration), and senile macular disciform degeneration. The various findings such lesions have in common will be noted, and a possible pathologic sequence in their formation will be suggested. VENOUS OBSTRUCTION Jensen1 described circinate lesions seen after branch venous obstruction as a perimacular zone of white exudate separated from a central yellowish-gray discolored area. He thought these were rarely occurring secondary phenomena most frequently preceded by hemorrhage. Seventeen of his sixty-one cases of branch venous obstruction showed circinate infiltrates. Some appeared as early as two months after the obstruction. Later, as they became more fully developed and typical, the exudates coalesced and lobed figures were formed. These circinate figures were sharply outlined, varied in size, appeared singly or in groups, and were located

A procedure for rapid induction of mycelial to yeast phase (M→Y) conversion ofHistoplasma capsulatum has been devised. Exposure of mycelial fragments to low oxidation-reduction (O/R) potentials (+5 to+65 mv) either aerobically (ascorbic acid treatment) or anaerobically (nitrogen atmosphere) for 18 to 24 hours at 37° C resulted in induction of the M→Y conversion process whether or not an organic sulfur source was available. However, aerobic conditions and a suitable organic sulfur source, such as cysteine, cystine or lanthionine were found essential for outgrowth and maintenance in the yeastlike phase.

The article discusses stud welding process in structural applications, studs classified on the basis of American Welding Society (AWS) D l.l Structural Welding Code and materials used un making Weld studs.

The first recorded case of primary hydatid cyst of the prostate is described. Treatment by transurethral resection has been completely successful, which suggests that the hypothetical dangers of seeding may not apply in practice to the urinary tract proper.

Complexes of formalinized Venezuelan equine encephalomyelitis (VEE) virus vaccine and specific IgG formed at antigen-antibody equivalence enhanced the immune responses of rhesus monkeys (Macaca mulatta). The predominant class of antibody elicited by the complexes was IgG. In contrast, lower titers of antibody and a more hiphasic (IgG-IgM) response were observed after exposure of monkeys to the vaccine alone. In comparison to the response of monkeys primed with antigen, a more rapid secondary response was obtained in monkeys primed with the complexes of antigen and antibody formed at equivalence. A sustained level of protection of 88% was afforded mice 24 hr after immunization with antigen-antibody complexes; development of protection after administration of antigen required eight days to reach this level. Passive protection (80%–100%) was conferred by IgG controls for seven to eight days after immunization. This level of protection was not significantly affected by X-irradiation 24 hr prior to administration of IgG; however, protection in mice similarly irradiated prior to immunization with antigen-antibody complexes was significantly decreased. Early protection afforded by the complexes was not nonspecific (interferon) but was mediated by specific immunologic mechanisms and may be caused by an early formation of IgG.

IN measuring doublet separations, the Fabry-Perot interferometer can be so adjusted that the fringes of one component fall half-way between those of the other. This eliminates most of the distortion present in other instruments. Using this method, the doublet separations at a pressure of 0.5 mm. and a current density of 0.25 amp. per sq. cm. have been found to be 0.316±0.002 for H, 0.329±0.005 for Hβ, and 0.353±0.007 for H. The wave-lengths of each component have also been determined and indicate that R= 109677.70± 0.04, with the use of Sommerfeld's formula.