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This study examined the lived experiences of seven beginning secondary mathematics teachers in an upper Midwestern state who had experienced mentoring and remained in teaching. The study sought to identify the mentoring experiences beginning secondary mathematics teachers perceive as most beneficial to their professional growth. Data were collected through individual interviews and focus groups and were analyzed by coding significant words and statements. Findings suggest beginning secondary mathematics teachers experience various types of support from assigned mentors and informal supports from colleagues within the same building. Regular observations with constructive feedback were found to be highly valued by beginning teachers.

This study used a video-based educational leadership simulation to create a safe environment for professional discourse with school leaders. The researchers used a simulation about teacher-to-teacher bullying with actors of different genders as a prompt. Two simulations were used in this study, and both simulations followed the same script. However, the twist in this study is that one simulation was filmed with only male actors, and the other simulation was filmed with female actresses and male actors. Participants from both simulations were brought together after experiencing one of the two simulations. This study utilized a sequential explanatory mixed methods approach and post-simulation focus groups revealed three themes: some school leaders would treat females differently than males, some school leaders believed the leadership style was a factor, and some believed that gender was less of a factor than the unique teacher-principal relationship. The first conclusion of this study is that the relationship between the principal and the teacher is critical to how the principal responds to a scenario. The second conclusion is that facilitating simulations is an effective method to model a safe environment for discourse centered on sensitive topics.

This paper presents a framework to enable probabilistic assessment for braced excavation-induced structural damage on a regional scale. Random filed models are created to describe the uncertainties of spatially variable ground displacements induced by excavation, and random variables are adopted to model the uncertainties of soil stiffnesses, structural stiffnesses, and building weights. The uncertainties are propagated to the probability distributions of building characteristic tensile strains (εc) through a Monte-Carlo method, in which a 3-dimensional (3D) soil-structure interaction (SSI) model is evaluated in each simulation. With limit state functions defined based on εc, damage probabilities were quantified for all buildings in the region impacted by the excavation. Fragility heatmaps that can be used for estimating the probabilities of each possible damage state from impact level were also generated for each building. The framework is demonstrated with an excavation case history executed in Oslo, Norway. The 3D SSI model adopted in the framework can provide more accurate building response prediction than conventional 2D analysis. Meanwhile, the probabilistic assessment method provides a tool to quantify the uncertainty effect in the building assessment of large excavation construction.

This paper presents an uncertainty quantification problem involving high-dimensional uncertainty inputs and a nonlinear structural analysis model. The uncertainty quantification problem can be considered a high-dimensional numerical integration with a nonlinear integrand. The crude Monte Carlo, multi-fidelity Monte Carlo, and randomized quasi-Monte Carlo methods are applied to solve the numerical integration problem, and numerical experiments are conducted to compare the efficiency of the Monte Carlo methods. It is shown that both multi-fidelity Monte Carlo and randomized quasi-Monte Carlo may significantly improve the efficiency of the studied problem. The randomized quasi-Monte Carlo method is easier to implement, but a carefully selected quasi-random sample and more sophisticated variance estimation are needed to successfully apply the randomized quasi-Monte Carlo method.

With the recent advances in the biogeotechnics field and specifically microbially induced calcite precipitation (MICP), cone penetration testing (CPT) has become a valuable tool to overcome the challenges associated with intact sampling of improved soils, evaluate the spatial extent and magnitude of the applied MICP treatment, and assess the consequential improvement of engineering properties. Although the CPT cone tip resistance (qc) can effectively monitor the improvement of densified clean sands, no relationship exists to estimate cementation and strength parameters in MICP-treated sands. This paper proposes a relationship between the apparent cohesion (c) stemming from the MICP-induced cementation bonds at particle contacts and the change in tip resistance (qc) in initially loose sands. To develop a broadly useful correlation, available experimental CPT data in biocemented soils were used to guide computation simulations using a direct axisymmetric model of cone penetration in biocemented sands. The CPT numerical model uses the finite-difference method with a rezoning algorithm for large-deformation problems along with the Mohr-Coulomb constitutive model. The biocemented sand was characterized by Mohr-Coulomb strength parameters and an elastic shear modulus informed by shear-wave velocity measurements (Vs). The correlation parameters of interest were identified (c, qc, and Vs), and results of the numerical simulations were validated against available experimental data. Once validated, the numerical simulations were extended to different initial conditions, and the trends between parameters of interest were analyzed and interpreted. Results from the simulations are consistent with experimental data and show an increase in the cone tip resistance as the cementation level increases. The cementation level is modeled through apparent cohesion and the shear stiffness model parameters, which both increase as the cementation level increases. A linear relationship is proposed between the apparent cohesion and the change in cone tip resistance as a function of the confining stress.

Lateral spreading of an interlayered deposit adjacent to a meandering stream channel in Wufeng, Taiwan, during the 1999 Chi-Chi Earthquake is evaluated using two-dimensional (2D) nonlinear dynamic analyses (NDAs) with geostatistical modeling of the subsurface to assess their ability to approximate the observed magnitude and spatial extent of ground deformations, as well as identify the key factors and mechanisms that most contributed to the overall system response. In-situ data from borings and cone penetration tests (CPTs) depict thinly stratified overbank deposits of low-plasticity silty sands, silts, and clays, interlayered with laterally discontinuous channel-deposited sands. The three-dimensional (3D) subsurface is simulated using transition probability-based indicator geostatistics, conditioned on available CPT data and geological inferences. The NDAs are performed using the PM4Sand and PM4Silt constitutive models, within the FLAC finite difference program. Sensitivity analyses are performed to understand the influence of uncertainties in the stratigraphy, channel conditions, soil properties, input ground motions, constitutive model calibration protocols, and numerical boundary conditions, as well as the performance of alternate channel transects. Most analysis cases generally matched the maximum displacements observed near the channel but overestimated the extent of displacements away from the channel. The most favorable results were largely influenced by nonstationary stratigraphic trends and cyclic softening of fine-grained soils, in addition to the liquefaction of coarse-grained soils. This case history demonstrates the capabilities and limitations of current subsurface and NDA modeling procedures for predicting ground deformation patterns.

This study explores the methodology presented in four leading educational leadership journals for a period of three years to investigate the predominant methodologies reported in journals most read by faculty members in educational administration or leadership programs. This content analysis study uses frequency and percentages to gather data on the published methodologies of four educational leadership journals. We used an established coding protocol, and our coding was not interpretive. The analysis revealed that qualitative methods were published more frequently than quantitative methods in the leading educational leadership journals with an emphasis on studies using a descriptive qualitative design, a descriptive quantitative design, correlational research, and case studies. This study replicated a study conducted by Wells, Kolek, Williams, and Saunders (2015) which was a content analysis of three major higher education journals to examine the methodologic characteristics of published research from 1996-2000 and 2006-2010 respectively. The authors discuss the relevance of the study for EdD programs in Educational Administration/Leadership. The analysis may inform decisions about how to best develop scholar-practitioners' capacity to use systemic and systematic inquiry to solve complex problems of practice.

This paper describes a centrifuge study undertaken to investigate how sand gradation affects the system-level performance of embankments subjected to strong shaking. Current analysis and design practices are primarily based on knowledge from case history records of liquefaction, with the majority of those from sites consisting of clean, poorly graded sands. The narrow range of gradation characteristics represented in the case history database poses a challenge during the analysis of embankment structures traditionally constructed with, or founded on, more broadly graded soils. The tests herein were designed to elucidate how embankments uniformly constructed with a well graded and poorly graded sand perform differently during earthquake shaking. A centrifuge experiment test program was developed and conducted using the 9-m-radius centrifuge at the UC Davis Center for Geotechnical Modeling. The experiment design consisted of two submerged 10-degree embankments positioned side-by-side in the same rigid model container, with one embankment constructed with poorly graded sand and the other with well graded sand. The embankments were dry pluviated to the same relative density, but the absolute densities of the sands were different. The embankments were identically instrumented with dense arrays of in-situ sensors beneath the level ground above the slope and in the mid-slope to measure the dynamic response during liquefaction. Results showed that embankments constructed at equal relative densities would both liquefy (i.e., ru reach 1.0), but deformations were less severe for the embankments constructed with the well graded sand. Greater resistance to the generation and faster dissipation of excess porewater pressures, coupled with stronger dilatancy of the well graded sand increased embankment stability, curtailing liquefaction-induced deformations.

Textured platens are often used to improve the transfer of shear stresses from the platens to the soil specimen during direct simple shear (DSS) tests. However, constant-volume DSS tests when textured platens are used can be affected by inadequate engagement of the soil at the platen-soil interface, leading to large reductions in the vertical stress at the start of shearing. The application of a preconditioning sequence involving small-strain drained cycles prior to constant-volume shearing can improve engagement at the platen-soil interface, but when excessively implemented, it can also have adverse effects on the measured soil behavior (e.g., strength, stiffness). A series of constant-volume cyclic DSS tests preceded by different preconditioning sequences was performed to evaluate the effect of preconditioning on the engagement of sand specimens at the platen-soil interface and the stress-strain response of these specimens. Results showed that textured platens that are properly engaged with sand specimens can reduce slippage at the platen-soil interface. This engagement can be achieved by applying a limited number of small-strain drained cycles at a low vertical stress while still obtaining representative soil behavior during the subsequent equivalent undrained constantvolume cyclic loading. Although the preconditioning protocol presented herein is specific to the testing equipment and materials considered, similar procedures may be adopted to develop preconditioning protocols for other soils, platens, and testing devices.

Rett syndrome (RTT) is a severe neurodevelopmental disorder primarily caused by heterozygous loss-of-function mutations in the X-linked gene MECP2 that is a global transcriptional regulator. Mutations in the methyl-CpG binding domain (MBD) of MECP2 disrupt its interaction with methylated DNA. Here, we investigate the effect of a novel MECP2 L124W missense mutation in the MBD of an atypical RTT patient with preserved speech in comparison to severe MECP2 null mutations. L124W protein had a limited ability to disrupt heterochromatic chromocenters due to decreased binding dynamics. We isolated two pairs of isogenic WT and L124W induced pluripotent stem cells. L124W induced excitatory neurons expressed stable protein, exhibited increased input resistance and decreased voltage-gated Na+ and K+ currents, and their neuronal dysmorphology was limited to decreased dendritic complexity. Three isogenic pairs of MECP2 null neurons had the expected more extreme morphological and electrophysiological phenotypes. We examined development and maturation of L124W and MECP2 null excitatory neural network activity using micro-electrode arrays. Relative to isogenic controls, L124W neurons had an increase in synchronous network burst frequency, in contrast to MECP2 null neurons that suffered a significant decrease in synchronous network burst frequency and a transient extension of network burst duration. A biologically motivated computational neural network model shows the observed changes in network dynamics are explained by changes in intrinsic Na+ and K+ currents in individual neurons. Our multilevel results demonstrate that RTT excitatory neurons show a wide spectrum of morphological, electrophysiological and circuitry phenotypes that are dependent on the severity of the MECP2 mutation.

Understanding the strain transfer mechanism is required to interpret strain sensing results for fiber optic cables. The strain transfer mechanism for fiber optic cables embedded in cementitious materials has yet to be thoroughly investigated experimentally. Interpretation of fiber optic sensing results is of particular concern when there is a displacement discontinuity. This study investigates the strain transfer mechanism for different types of fiber optic cables while embedded in concrete cubes, sustaining a boundary condition which features a displacement discontinuity. The strain transfer mechanisms for different cables are compared under increasing strain levels. Under cyclic loading, the nonlinear behavior of the force-displacement relation and of the strain distribution in the fiber optic cable are discussed. The mechanical properties of the fiber optic cables are presented and discussed. A parameter is proposed to quantify the strain transfer length. The results of this study will assist researchers and engineers to select appropriate cables for strain sensing and interpret the fiber optic sensing results.

Distributed fiber-optic sensing (DFOS) technologies have been used for decades to detect damage in infrastructure. One recent DFOS technology, Optical Frequency Domain Reflectometry (OFDR), has attracted attention from the structural engineering community because its high spatial resolution and refined accuracy could enable new monitoring possibilities and new insight regarding the behavior of reinforced concrete (RC) structures. The current research project explores the ability and potential of OFDR to measure distributed strain in RC structures through laboratory tests on an innovative beam-column connection, in which a partial slot joint was introduced between the beam and the column to control damage. In the test specimen, fiber-optic cables were embedded in both the steel reinforcement and concrete. The specimen was tested under quasi-static cyclic loading with increasing displacement demand at the structural laboratory of the Pacific Earthquake Engineering Research (PEER) Center of UC Berkeley. Different types of fiber-optic cables were embedded both in the concrete and the rebar. The influence of the cable coating and cable position are discussed. The DFOS results are compared with traditional measurements (DIC and LVDT). The high resolution of DFOS at small deformations provides new insights regarding the mechanical behavior of the slotted RC beam-column connection, including direct measurement of beam curvature, rebar deformation, and slot opening and closing. A major contribution of this work is the quantification of the performance and limitations of the DFOS system under large cyclic strains. Performance is quantified in terms of non-valid points (which occur in large strains when the DFOS analyzer does not return a strain value), maximum strain that can be reliably measured, crack width that causes cable rupture, and the effect of the cable coating on the measurements. Structural damage indices are also proposed based on the DFOS results. These damage indices correlate reasonably well with the maximum sustained drift, indicating the potential of using DFOS for RC structural damage assessment. The experimental data set is made publicly available.

This case study presents an application of a conditional transition probability method for interpreting subsurface stratigraphy for the interbedded alluvium underlying Perris Dam, and evaluating the effects of stratigraphic uncertainty on nonlinear dynamic analysis (NDA) results for design earthquake loading. The challenges involved in synthesizing information from different sources (i.e., geologic conditions, site investigation tools, lab data, field classifications) into soil categories for interbedded alluvium were examined. The application of conditional transition probability methods for developing three-dimensional (3D) realizations of the upper Holocene and lower Pleistocene alluvial strata over a 305-m-wide interval along the dam alignment is described, including challenges with insufficient data and limitations involved with utilizing a stationary, geostatistical method for approximating nonstationary geologic conditions. Two-dimensional (2D) NDA models of Perris Dam were created by slicing the 3D transition probability realizations into five 2D cross sections. The constitutive models PM4Sand and PM4Silt were used to model the sand and clay soil categories in the alluvial strata, as well as the different zones in the embankment. The deformations and variability in deformations for each cross section were compared, and sensitivity studies were completed to examine the impact of several factors, including impacts of the small-strain shear modulus for the alluvium, mean lengths and sills for the alluvium categories, strengths for each alluvium soil category, and different ground motions. NDA cross sections of Perris Dam with uniformly (noncategorical) distributed properties were performed with and without additional deterministic embedded soil lenses, and the deformations were compared with transition probability models and deterministic models completed by others. The use of conditional transition probability models for NDAs of Perris Dam, along with implications and lessons for practice, are discussed.

Two-dimensional nonlinear dynamic analyses (NDAs) are performed for a series of hypothetical embankment dams on a spatially variable liquefiable foundation layer to evaluate the utility of representing the foundation layer with random fields conditioned on different levels of site characterization information. A set of two-dimensional parent models (PMs), each representing a true foundation condition, were generated using unconditional random fields of equivalent clean sand, corrected standard penetration test (N1)60cs values. Different levels of site characterization were then represented by combining different numbers of local borings (i.e., columns of data from the PM) with the optional inclusion of constraints on the geostatistical properties that might come from sitewide explorations. NDAs were performed using the same input motions for the PM (which represents perfect knowledge of soil conditions), a set of realizations conditioned on the local borings alone, and a set of realizations conditioned on the local borings with sitewide statistics. Embankment deformations obtained for the conditional realizations are compared to those for the PM to evaluate the potential benefits of increasing levels of site characterization in terms of deformation prediction accuracy. Parametric analyses include varying the embankment size, scales of fluctuation in the foundation stratum, number of conditioning borings, and ground motions. The results of these comparisons illustrate that the beneficial effects of using conditional random fields were generally limited to cases with the horizontal scale of fluctuation approaching the scale of the embankment base width and to cases with a large number of borings (more than three borings per horizontal scale of fluctuation), which may not be practical in many situations. Additional potential benefits and limitations of using conditional random fields for representing spatial variable liquefiable foundation layers in embankment dam NDAs are discussed.

Maintenance of wind turbine towers is currently a manual process that requires visual inspection and bolt tightening yearly. This process is costly to energy companies and its necessity is not well-defined. In this study, two Rayleigh-based distributed fiber optic sensing technologies are evaluated and compared for their ability to monitor the dynamic structural behavior of a model wind turbine tower subject to free and forced vibration. They are further tested for their ability to detect structural phenomena associated with loose bolts and material damage within the tower. The two technologies examined are optical frequency domain reflectometry (OFDR) and phase-based optical time domain reflectometry (ϕ-OTDR), which is a technology used in distributed acoustic sensing (DAS). OFDR is a tested and proven strain measurement technology commonly used for structural health monitoring but can only make strain measurements over short distances (10 s of meters). OFDR was used to validate the measurements made with ϕ-OTDR which can measure over much longer distances (several kilometers). Due to its sensing distance capability, ϕ-OTDR is a promising technology for monitoring many wind turbines networked together with a single fiber optic cable. This study presents a first-of-its-kind use of ϕ-OTDR for structural health monitoring to demonstrate its capabilities.

The 9-m and 1-m radius geotechnical centrifuges at the Natural Hazards Engineering Research Infrastructure (NHERI) facility at the University of California at Davis provide the national research community with open access to unique and versatile modeling capabilities for advancing methods to predict and improve the performance of soil and soil-structure systems affected by earthquake, wave, wind, and storm surge loadings. Large-scale centrifuge models are particularly effective for the building of basic science knowledge, the validation of advanced computational models from the component to the holistic system level, and the validation of innovative soil remediation strategies. The capabilities and unique role of large-scale centrifuge modeling are illustrated using three example research projects from the shared-use NHERI facility. Education impacts stemming from operations activities and coordination of activities by the center’s user base are discussed. Future directions and opportunities for research using the NHERI facilities are discussed.

The 9-m and 1-m radius geotechnical centrifuges at the Natural Hazards Engineering Research Infrastructure (NHERI) facility at the University of California at Davis provide the national research community with open access to unique and versatile modeling capabilities for advancing methods to predict and improve the performance of soil and soil-structure systems affected by earthquake, wave, wind, and storm surge loadings. Large-scale centrifuge models are particularly effective for the building of basic science knowledge, the validation of advanced computational models from the component to the holistic system level, and the validation of innovative soil remediation strategies. The capabilities and unique role of large-scale centrifuge modeling are illustrated using three example research projects from the shared-use NHERI facility. Education impacts stemming from operations activities and coordination of activities by the center’s user base are discussed. Future directions and opportunities for research using the NHERI facilities are discussed.

Simulations have long been used for military and medical training. More recently educational simulations have evolved for training teachers and for gaming used as a tool to engage students in learning. Only recently have educational simulations been available to train school leaders who have increased demands on them to lead schools and to improve test scores. Educational leaders must be versed in a variety of managerial and instructional skills that are supremely difficult to develop in any degree or certification program. The researchers in this study used educational simulations to support graduate instruction in two different principal and superintendent preparation programs. Participants were surveyed after participating in four or more educational simulations. The study uncovered a unanimously positive perception from participants regarding their preparedness for leadership and ability to meet graduate course objectives utilizing the educational simulations. Overall, the participants reported increased confidence to handle real-life situations after engaging in the simulations, more engagement in graduate courses and a deeper perspective to think critically about issues they will be presented with in the field. Data from participants in the study provide real insights to principal preparation programs, aspiring school leaders, and districts interested in further training their current leaders.

Microbially Induced Calcite Precipitation (MICP), or bio-cementation, is a promising bio-mediated technology that can improve the engineering properties of soils through the precipitation of calcium carbonate. Despite significant advances in the technology, concerns regarding the fate of produced NH4+ by-products have remained largely unaddressed. In this study, five 3.7-meter long soil columns each containing one of three different soils were improved using ureolytic bio-cementation, and post-treatment NH4+ by-product removal was investigated during the application of 525 L of a high pH and high ionic strength rinse solution. During rinsing, reductions in aqueous NH4+ were observed in all columns from initial concentrations between ≈100 mM to 500 mM to final values between ≈0.3 mM and 20 mM with higher NH4+ concentrations observed at distances furthest from the injection well. In addition, soil Vs measurements completed during rinse injections suggested that no significant changes in cementation integrity occurred during NH4+ removal. After rinsing and a 12 hour stop flow period, all column solutions achieved cumulative NH4+ removals exceeding 97.9%. Soil samples collected following rinsing, however, contained significant sorbed NH4+ masses that appeared to have a near linear relationship with surrounding aqueous NH4+ concentrations. While these results suggest that NH4+ can be successfully removed from bio-cemented soils, acceptable limits for NH4+ aqueous concentrations and sorbed NH4+ masses will likely be governed by site-specific requirements and may require further investigation and refinement of the developed techniques.

The effects of soil plasticity and penetration rate on cone penetration resistance in low-plasticity fine-grained soils are evaluated. A series of centrifuge tests with in-flight variable rate cone penetration soundings was performed on models of four slurry deposited mixtures of nonplastic silica silt and kaolin clay (0%, 2.5%, 5%, and 20% kaolin by dry mass) with plasticity indices ranging from 0 to 6. Cone penetration resistances for an effective overburden stress of 100 kPa ranged from 26 to 40 MPa (260 to 400 atm) in the nonplastic silica silt to 0.4-1.8 MPa (4-18 atm) in the silt-clay mixture with a plasticity index of 6. The addition of a small amount of clay (as little as 2.5% by dry mass) to nonplastic silt resulted in an order of magnitude decrease in drained penetration resistance. Faster penetration rates produced partially drained and undrained conditions, with negative excess pore pressures developing in the nonplastic silica silt and positive excess pore pressures developing in the mixtures with 5% and 20% kaolin.

The effects of partial drainage on the cyclic strength of saturated sand in a set of dynamic centrifuge model tests were evaluated. Three models of level profiles of saturated Ottawa F-65 sand with initial relative densities of 25%, 43%, and 80% were tested using a 9-m-radius centrifuge. Models were subjected to multiple sinusoidal shaking events with acceleration amplitudes ranging from 0.03g to 0.55g. The cyclic resistance ratios (CRR) obtained from inverse analyses of dense accelerometer and pore pressure transducer arrays were correlated with cone penetration resistances (qc1N) from in-flight cone penetration tests. Time histories of volumetric strain and surface settlement due to partial drainage were determined by inverse analyses of the array data and compared with measured surface settlements. The effect of volumetric strain on cyclic strength is examined through single-element simulations using the constitutive model PM4Sand version 3. Results of these simulations are compared to prior laboratory and numerical studies investigating the effect of partial saturation on cyclic strength. The magnitude of the volumetric strains developed in the centrifuge models due to partial drainage and their effects on the centrifuge CRR-qc1N correlation are examined.

Trees in seasonal climates gauge winter progression to assure vital and productive blooming. However, how dormant plants asses environmental conditions remains obscure. We postulated that it involves the energetic reserves required for bloom, and therefore studied winter carbohydrate metabolism in deciduous trees. We quantified non-structural carbohydrates throughout winter in almond, peach, and pistachio trees in California and Israel and characterized winter metabolism. We constructed a carbohydrate-temperature (C–T) model that projects changes in starch and soluble carbohydrate concentrations by temperature mediated kinetics. Then, we tested the C–T model projections of bloom times by 20 years of temperature and phenology records from California. The C–T model attributes winter carbohydrate regulation in dormant trees to continuous updates of metabolic pathways. The model projects a surge in starch synthesis at the end of winter, and critically low concentrations of soluble carbohydrates, that trigger bloom. This is supported by field measurements of starch accumulation at the end of winter (˜50 mg g−1 DW in almonds) that preceded bloom by ˜10 days. The C–T model provides a physiological framework for bloom forecasts in deciduous orchards. It integrates contrasting notions of chill and heat and elucidates why abnormal winter temperatures may compromise bloom in deciduous orchards.

Trees in seasonal climates gauge winter progression to assure vital and productive blooming. However, how dormant plants asses environmental conditions remains obscure. We postulated that it involves the energetic reserves required for bloom, and therefore studied winter carbohydrate metabolism in deciduous trees. We quantified non-structural carbohydrates throughout winter in almond, peach, and pistachio trees in California and Israel and characterized winter metabolism. We constructed a carbohydrate-temperature (C–T) model that projects changes in starch and soluble carbohydrate concentrations by temperature mediated kinetics. Then, we tested the C–T model projections of bloom times by 20 years of temperature and phenology records from California. The C–T model attributes winter carbohydrate regulation in dormant trees to continuous updates of metabolic pathways. The model projects a surge in starch synthesis at the end of winter, and critically low concentrations of soluble carbohydrates, that trigger bloom. This is supported by field measurements of starch accumulation at the end of winter (˜50 mg g−1 DW in almonds) that preceded bloom by ˜10 days. The C–T model provides a physiological framework for bloom forecasts in deciduous orchards. It integrates contrasting notions of chill and heat and elucidates why abnormal winter temperatures may compromise bloom in deciduous orchards.

A set of saturated Ottawa sand models was treated with microbially induced calcite precipitation (MICP) and subjected to repeated shaking events using the 1-m radius centrifuge at the UC Davis Center for Geotechnical Modeling. Centrifuge models were constructed to initial relative densities (DR0) of approximately 38% and treated to light, moderate, and heavy levels of cementation (calcium carbonate contents by mass of approximately 0.8%, 1.4%, and 2.2%, respectively) as indicated by shear wave velocities (light≈200 m/s, moderate≈325 m/s, and heavy≈600 m/s). The cemented centrifuge models were compared to a pair of uncemented saturated Ottawa sand models with initial DR0≈38 and 53% and subjected to similar levels of shaking. Cone penetration resistances and shear wave velocities were monitored throughout shaking to investigate (1) the effect of cementation on cone penetration resistance, shear wave velocity, and cyclic resistance to liquefaction triggering; and (2) the effect of shaking on cementation degradation. Accelerometers, pore pressure transducers, and a linear potentiometer were used to monitor the effect of cementation on liquefaction triggering and consequences. Cone penetration resistances and shear wave velocities were sensitive to light, moderate, and heavy levels of cementation (increases in penetration resistance from 2 to 5 MPa, from 2 to 10 MPa, and from 2 to 18 MPa and increases in shear wave velocity from 140 to 200 m/s, from 140 to 325 m/s, and from 140 to 660 m/s, respectively), and were able to capture the effects of cementation degradation.

Mechanistic approaches to developing cone penetration test-based liquefaction triggering correlations are presented and evaluated with an application to Ottawa sand. The mechanistic approaches utilize combinations of data from undrained cyclic direct simple shear tests, dynamic geotechnical centrifuge tests with in-flight cone penetration profiles, and cone penetration simulations. Cyclic direct simple shear tests on Ottawa sand characterize the relationship between cyclic resistance ratio (CRR) and relative density (DR). Relationships between cone tip resistance (qc) and DR are developed from geotechnical centrifuge tests and cone penetration simulations. Penetration simulations using the MIT-S1 constitutive model with three different calibrations for Ottawa sand examine the role of critical state line shape and position on simulated qc values. The CRR-DR relationship from laboratory tests is composed with measured and simulated qC-DR relationships via common DR values to develop CRR-qc relationships. An alternative CRR-qc relationship is developed from inverse analyses of centrifuge test sensor array data (i.e., arrays of accelerometers and pore pressure sensors). The results of these different approaches are compared to case history-based correlations for clean sand and their relative merits discussed. Recommendations are provided for future application of these mechanistic approaches to developing liquefaction-triggering correlations of poorly characterized or unique soils.

The performance of Çark Canal in the 1999 M=7.5 Kocaeli earthquake was evaluated using common liquefaction vulnerability index (LVI) methods, a nonlinear dynamic analysis (NDA) method, and a Newmark sliding block method to examine possible factors contributing to why different analysis approaches often overestimate liquefaction effects in interbedded deposits. The characterization of the interbedded fluvial stratum based on cone penetration test (CPT) data utilized an inverse filtering procedure to correct CPT data for thin-layer and transition zone effects. Common LVIs computed using the measured and inverse-filtered CPT data with a site-specific fines content calibration showed that the combination of these two steps reduced the LVIs by 30%-50% for this site and seismic loading. Two-dimensional NDAs were performed using stochastic realizations for the interbedded stratum and the PM4Sand and PM4Silt constitutive models for the sandlike and claylike portions, respectively. Computed deformations were evaluated for their sensitivity to stochastic model parameters, the cyclic strength assigned to the sandlike soils, the undrained shear strengths assigned to the claylike soils, the level of shaking, and other input parameters. Newmark sliding block analyses were performed with different allowances for the influence of interbedding on the composite strength of the interbedded stratum. The differences between results obtained with these analysis methods, along with those presented by others, provided insights into how the various factors can contribute to an overestimation of ground deformations in interbedded deposits of sands, silts, and clays.

Microbially Induced Calcite Precipitation (MICP) is a bio-mediated cementation process that can improve the engineering properties of granular soils through the precipitation of calcite. The process is made possible by soil microorganisms containing urease enzymes, which hydrolyze urea and enable carbonate ions to become available for precipitation. While most researchers have injected non-native ureolytic bacteria to complete bio-cementation, enrichment of native ureolytic microorganisms may enable reductions in process treatment costs and environmental impacts. In this study, a large-scale bio-cementation experiment involving two 1.7-meter diameter tanks and a complementary soil column experiment were performed to investigate biogeochemical differences between bio-cementation mediated by either native or augmented (Sporosarcina pasteurii) ureolytic microorganisms. Although post-treatment distributions of calcite and engineering properties were similar between approaches, the results of this study suggest that significant differences in ureolysis rates and related precipitation rates between native and augmented microbial communities may influence the temporal progression and spatial distribution of bio-cementation, solution biogeochemical changes, and precipitate microstructure. The role of urea hydrolysis in enabling calcite precipitation through sustained super-saturation following treatment injections is explored.

Background and aimsIn peach (Prunus persica) trees, three types of shoots can be distinguished depending on the time of their appearance: sylleptic, proleptic and epicormic. On proleptic shoots, an average of ten phytomers are preformed in dormant buds prior to shoot growth after bud-break, whereas all phytomers are considered neoformed in sylleptic and epicormic shoots. However, casual observations indicated that proleptic and sylleptic shoots appear quite similar in number of phytomers and structure in spite of their different origins. The goal of this research was to test the hypothesis that both proleptic and sylleptic shoots exhibit similar growth characteristics by analysing their node numbers and bud fate patterns. If their growth characteristics are similar, it would indicate that the structure of both types of shoots is primarily under genetic rather than environmental control.MethodsThe number of phytomers and bud fate patterns of proleptic and sylleptic shoots of four peach cultivars grown in the same location (Winters, California) were analysed and characterized using hidden semi-Markov models. Field data were collected during winter 2016, just prior to floral bud-break.Key resultsSylleptic shoots tended to have slightly fewer phytomers than proleptic shoots of the same cultivars. The bud fate patterns along proleptic and sylleptic shoots were remarkably similar for all the cultivars, although proleptic shoots started growing earlier (at least 1 month) in the spring than sylleptic shoots.ConclusionsThis study provides strong evidence for the semi-deterministic nature of both proleptic and sylleptic shoots across four peach cultivars in terms of number of phytomers and bud fate patterns along shoots. It is apparent that the overall structure of shoots with similar numbers of phytomers was under similar genetic control for the two shoot types. Understanding shoot structural characteristics can aid in phenotypic characterization of vegetative growth of trees and in providing a foundation for vegetative management of fruit trees in horticultural settings.

The effects of shaking history on cone penetration test (CPT)-based liquefaction triggering correlations for clean saturated sand are examined by using cone penetration resistance and cyclic strength data pairs from dynamic centrifuge model tests. Three model tests on a 9-m-radius centrifuge examined the liquefaction responses of level profiles of saturated Ottawa F-65 sand subjected to multiple (17-29) shaking events that produced successive changes in density and model response characteristics. Inverse analysis of data from dense accelerometer arrays were used to define time series of cyclic stress ratios and shear strains throughout the profile. Cyclic resistance ratios against triggering of ~100% excess pore pressure ratio in 15 equivalent uniform cycles were computed at multiple depths based on weighting of the cyclic stress ratio time series up to the time of triggering. Cone penetration tests performed at select times during each model test were used to define the variation in cone tip resistances with depth and shaking history. The resulting data pairs, with normalized cone tip resistances ranging from 20 to 340 and cyclic resistance ratios ranging from 0.1 to 2.0, show that both quantities progressively increase as a result of recurrent liquefaction events and generally follow the trends predicted by case history-based liquefaction triggering correlations. Three 1-m-radius centrifuge tests of similar configurations produced consistent results. Implications for the interpretation of case histories and engineering practice are discussed.