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Persons with mental illness (PWMI) experience rejection, isolation, and discrimination in employment, education, and housing due to the prejudice associated with the illness. Families affiliated with PWMI often internalize the public's prejudice towards mental illness. Such internalized stigma can further impact the health and quality of life of both PWMI and their families. This study aimed to examine the level and correlates of internalized stigma in family members of PWMI in Qatar. A cross-sectional study of 106 family members was conducted using the Family Internalized Stigma Mental Illness Scale. The mean stigma score was 2.04 suggesting a mild level of stigma overall. Being married was found to be a predictor of higher levels of internalized stigma, while having college education or higher predicted lower levels of stigma. The overall stigma scores among family members were not high, which may reflect the protective stance families take towards about their relatives with mental illness. Some sociodemographic attributes predicted trends in internalized stigma among our surveyed sample. Future research efforts in this area may help increase understanding of internalized stigma in this population to inform stigma reduction efforts. [ABSTRACT FROM AUTHOR]

We report explorations into prompt engineering with large pre-trained language models that were not fine-tuned to solve the legal entailment task (Task 4) of the 2023 COLIEE competition. Our most successful strategy used simple text similarity measures to retrieve articles and queries from the training set. We report on our efforts to optimize performance with both OpenAI's GPT-4 and FLaN-T5. We also used an ensemble approach to find the best combination of models and prompts. Finally, we analyze our results and suggest ideas for future improvements. [ABSTRACT FROM AUTHOR]

In this work, the fracture toughness of limestone was determined utilizing advantage edge-notched disc (END) type specimens. The normalized Phase I stress high transformational of limestone was calculated using a novel method. The samples’ Mode I (opening)-fracture toughness was accurately calculated using the flexible finite element method (FEM) to develop this helpful formula. The notched Brazilian discs (NBD) were used in a lab experiment to test the accuracy of the END procedure. To recreate these tests numerically and verify the correctness of the fracture toughness measurements, a discrete element analysis of the END tests was also performed. The findings of the numerical simulations and the fracture extension patterns derived from the experimental testing showed excellent agreement. The toughness levels determined by END studies, however, were less than those specified by NBD testing. This is because the notch in the END limestone sample has a uniform tensile stress distribution. [ABSTRACT FROM AUTHOR]

Determination of the rock elastic parameters is essential in geomechanical studies. Among the elastic parameters, Young's modulus (YM) and Poisson's ratio (PR) have many applications in wellbore stability analysis, hydraulic fracturing, casing design, and sand production. In this study, the machine learning methods, including adaptive Neuro-Fuzzy inference system (ANFIS), artificial neural network (ANN), and support vector machine (SVM) are used to predict the rock elastic parameters. Using these models requires measuring the static elastic parameters, so 34 laboratory tests are used to develop empirical correlations between static elastic and dynamic elastic parameters. Then, the static elastic parameters at all logged intervals are calculated by applying the suggested empirical correlations. To demonstrate the capabilities of the ANFIS, ANN, and SVM methods, DT, RHOB, and NPHI data are used as inputs, and YM and PR data are used as outputs. The performance of single models can be enhanced using ensemble models, such as simple averaging ensemble (SAE), weighted averaging ensemble (WAE), and neural network ensemble (NNE). The results of the single models showed that ANN models performed better overall than other single models. The results also showed that ensemble models predicted elastic parameters better than single models. This shows that NNE model with R2 of 0.998 and 0.993, MAPE error values of 0.0041 and 0.0010, and RMSE error values of 0.58 and 0.0029 for the training data of YM and PR is more accurate and reliable than SAE, WAE and single models. [ABSTRACT FROM AUTHOR]

Background: Frailty makes older adults vulnerable to adverse health outcomes and can modify pharmacokinetics and drug exposure. Objective: We aimed to explore the relationship between different frailty assessments and trough plasma concentrations of direct oral anticoagulants in older patients. Methods: The frailty status of adults aged ≥ 70 years receiving regular direct oral anticoagulant medication was assessed by four different instruments: Fried physical phenotype, Rockwood frailty index, Short Physical Performance Battery, and FRAIL scale. The two performance measures "slow gait speed" and "weak grip strength" were used to build a separate score depending on the number of positive criteria (none, one, two). For each participant, a single steady-state direct oral anticoagulant trough plasma concentration was collected, dose-normalized, and its relationship to the various frailty assessments analyzed. Results: Forty-two participants completed the study, with most using apixaban (n = 22). Dose-normalized apixaban trough concentrations were 2.48-fold higher in frail participants (Fried phenotype) than in robust participants (p = 0.009) and correlated positively with Fried physical phenotype (rs = 0.535, p = 0.010) and negatively with Short Physical Performance Battery (rs = − 0.434, p = 0.044). Compared with participants who met none of the criteria "slow gait speed" and "weak grip strength", apixaban trough concentrations were approximately 1.9-fold higher in participants who were positive for one (p = 0.018) or two (p = 0.013) of these measures. Conclusions: In this exploratory study, higher levels of frailty on performance-based frailty assessments were associated with higher apixaban exposure in older adults. Clinical Trial Registration: German Clinical Trials Register DRKS00016741; registered 20 February, 2019. [ABSTRACT FROM AUTHOR]

The current research scrutinizes the effects of axial loading width and immediate roof thickness on the failure mechanism of a notched roof in room and pillar mining by experimental test and numerical simulation. Gypsum specimens with dimensions of 150 mm × 150 mm × 50 mm containing two rooms and a middle immediate roof (with and without the presence of an edge notch) were prepared for this purpose. The immediate roof has three different thicknesses, i.e., 30 mm, 45 mm, and 60 mm. The length of the edge notches was 1 cm, and their angles were 45°, 90°, and 135°. The upper room was loaded under axial loading with a width of 50 mm. A total of 12 physical specimens were tested. Concurrent with experimental tests, 36 numerical models were simulated. The model geometry was similar to the experimental one, but the upper room was loaded under three different axial loadings, i.e., 10 mm, 30 mm, and 50 mm. The results show that the notch angle, roof thickness, and loading width affect the failure pattern and compressive strength of models. The immediate-edged roof with an angle of 45 has a critical condition compared to other configurations. Also, models under a loading width of 50 mm have less compressive strength compared to other loading widths. The experimental test and numerical simulation show similar outcomes. Highlights: The effects of axial loading width and immediate roof thickness on the failure mechanism of a notched room by experimental test and numerical simulation are investigated. Gypsum specimens with dimensions of 150 mm × 150 mm × 50 mm containing two rooms and a middle immediate roof (with and without the presence of an edge notch) were prepared. The results show that the notch angle, roof thickness, and loading width affect the failure pattern and compressive strength of models. The immediate-edged roof with an angle of 45 has a critical condition compared to other configurations. [ABSTRACT FROM AUTHOR]

The effects of different configurations of echelon crack on the crack propagation mechanism in the gypsum samples with different lengths and crack inclination angles under the uniaxial compressive loading condition were studied. These samples were explicitly prepared in the laboratory and tested uniaxially under compression. Bridge areas were specified by considering the 2 cm distance between the cracks. These samples contained echelon cracks with varying inclination angles of 0°, 30°, 60°, and 90°. Therefore, twelve samples with different configurations were provided and tested to investigate the effects of echelon cracks on the crack extension mechanisms of the rock-like materials under compression. These two sets of results provided an accurate and robust methodology for studying the crack extension mechanism of the rock-like materials. [ABSTRACT FROM AUTHOR]

The direct tensile strength of hard rocks such as granite was measured using hollow disk-type specimens in the form of rock rings. These specimens were placed in a novel apparatus that transferred the compressive load to the tensile load during the direct tensile test. Before performing the laboratory tests on the actual geomaterial specimens, the numerical modeling of the hollow disk specimens of granite (with five different hole diameters) was accomplished in the two-dimensional particle flow code (PFC2D). It was found that the best tensile loading condition is for the case of 15-cm-diameter specimens. Therefore, the experimental tests for the direct tensile testing apparatus using the compressive-to-tensile load-transferring (CTLT) device were carried out on the granite specimens with 15 cm holes. The indirect Brazilian tensile strength of granite was also measured in the laboratory to calibrate the numerical code and compare the indirect and direct values of the tensile strengths of the geomaterials. The indirect and direct tensile strength tests were simulated with PFC2D. The measured tensile strength values of the granite hollow disk specimens were compared with the corresponding numerical results. The numerical code was calibrated by adjusting the proper microparameters for the rock specimens. Additionally, the direct and indirect tensile testing results were compared, and a good correlation was made. These results showed that the direct tensile strength of granite obtained by the CTLT device is lower than that of the indirect one obtained from the Brazilian disk approach. [ABSTRACT FROM AUTHOR]

In this paper, the capability of a four-point bending test to determine the failure mechanism of ligaments was investigated using PFC2D. For this purpose, various configurations of ligaments (i.e., the distance between the internal tips of two cracks) were prepared and tested by a four-point bending test. First, a rectangular model consisting of two nonpersistent cracks was prepared. The crack length and crack position vary in different models. Additionally, the configuration of the loading walls is different to reach different four-point bending test conditions. The numerical results show that in some cases, the ligament fails under the bending test. In other cases, cracks initiate from other unfavorable places where ligaments are absent. Finally, for comparison, the higher-order displacement discontinuity is modified and used to investigate the mechanism of crack coalescences in the ligament based on linear elastic fracture mechanics (LEFM). The two modeled failure patterns are compared, and the proposed approaches are validated to study the breakage mechanism of the concrete specimens in a four-point test. [ABSTRACT FROM AUTHOR]

The hollow Brazilian disc-type specimens of transversely bedded geo-materials were numerically modeled using the particle discrete element codes PFC2D for investigating the mechanical behavior and failure mechanism of the transversely isotropic rocks. The breakage mechanism and tensile strength of the transversely isotropic layered rocks were numerically studied using the hollow disc specimens. This numerical code was calibrated by the indirect tensile testing accomplished on the Brazilian disc specimens in the laboratory. Then, about 21 modeled hollow disc specimens with an outer diameter of 100 mm were considered. These specimens were established with two bedding layers in which the first one was the weakest layer with low mechanical characteristics and the second layer had relatively high mechanical parameters (close to those of the intact geo-material). In this study, the angle of the first (weak) layer relative to the applied loading direction varied. The angle of the second (stronger) layer was kept constant (i.e., 180° with respect to the loading direction). The numerical results showed that tensile cracks could develop in the weak layer, and their number decreased as the weak layer's thickness increased. On the other hand, the strong layer experienced no failure during the loading process. [ABSTRACT FROM AUTHOR]

The failure behavior and mechanism of fracturing in the gypsum specimens containing vertical notches under uniaxial compression was investigated in this study. The experimental tests and their corresponding numerical simulations were accomplished to explain the effects of vertical notches (edge cracks). Effects of the number of vertical joints on the mechanical behavior of gypsum specimens containing vertical notches were studied experimentally and numerically using some specimens of 5.4 cm×10.8cm×5.4 cm in dimensions. Then, the two-dimensional particle flow code (PFC2D) was used to numerically simulate the gypsum specimens under uniaxial compressive loading. Both, the laboratory experiments and numerical models worked out on the gypsum specimens with edge cracks (vertical notches) explained the effects of the vertical notches and their number on the failure mechanism and fracturing pattern of the specimens. These studies elucidated the dominant tensile failure behavior of the specimens with cracks under the uniaxial compressive loading condition. They also showed the great dependence of fracture pattern and failure stresses on the number of the vertical notches. The experimental and numerical results are also compared with one another correspondingly and it has been concluded that these two sets of results are very similar and there is little difference in between them. [ABSTRACT FROM AUTHOR]

The diagrams for damage location and convergence curves based on the differential evolutionary algorithms under the loading modes I, II, III, and IV are studied for the pre-cracked concrete specimens with a center crack of different inclination angles and considering the noise effect. The numerical results for the modeled specimens showed that the measured noise may have significant effects on these diagrams, especially when the center cracks are of high inclination angles (greater than 45°) with respect to the applied loading direction. It was also shown that the measured noise might distort the accelerations in the damaged concrete specimens, which highlighted the effectiveness of the present algorithm provided via MATLAB. In this study, an algorithm is established in the MATLAB software to numerically simulate the noise effect on the damage location and convergence diagrams for the cubic concrete specimens based on the differential evolutionary algorithm. The particle flow code for two-dimensional (PFC2D) problems was used to simulate crack propagation paths in the numerically failed pre-cracked concrete specimens. [ABSTRACT FROM AUTHOR]

In this study, pre-cracked cubic specimens of concrete materials were especially prepared in a concrete laboratory to study the breaking process of brittle solids. Then, the linear elastic fracture mechanics concept of the stress intensity factor and the experimental methods were used to investigate the failure mechanism of pre-cracked concrete specimens under compression. The crack propagation mechanism and the ultimate strengths of these specimens were obtained in the laboratory. Several numerical analyses were also carried out on the pre-cracked specimens, using the finite element method and ABAQUS software package. The damage location and convergence diagram of the differential evolutionary algorithm under mode I, II, III or IV loading conditions were investigated for the cubic pre-cracked concrete specimens containing a single center crack with different inclination angles. The crack propagation mechanisms obtained numerically were compared with the corresponding experimental ones proving the proposed method's feasibility. [ABSTRACT FROM AUTHOR]

The experimental tests and discrete element method were adopted to study the interaction between concrete-gypsum interface and internal notch. Gypsum and concrete semi circular ring type samples with diameter of 10 cm and heigth of 10 cm were prepared seperatly. Then one gypsum sample and one concrete sample were attached to each other with glue. The midlle space between gypsum-concrete interface dose not have any glue so one joint was built in this space. The lengths of joints were 2cm, 4cm, and 6 cm. In experimental tests, the joint direction related to loading axis changes from 0° to 90° with an increment of 30°. Totally 12, experimental test were performed. in numerical tests, the joint direction related to loading axis changed as 0° to 90° by 15° increments. As a whole, 21 numerical tests were simulated. This study demonstrates that the failure and fracturing processes in the cracked or jointed specimens containing interfaces are mostly governed by the joint or crack direction related to general loading axis. The tensile failure of various specimens containing interfaces mainly dependens on the failure and fracture mechanisms of the weakness planes due to discontinuities and the gupsum-concrete interface direction. Increasing the joint or crack length causes a decrease in the tensile strength of the concrete-gypsum specimens. It is shown that the experimental and numerical results are very close to each other. Therefore, the applicability and usefulness of the present analyzes can be easily attested. [ABSTRACT FROM AUTHOR]

Tropical cyclones can dramatically reduce coral cover, coral diversity and structural complexity, which can all cause flow-on effects to fish communities. In 2016, Fiji sustained extensive damage from one of the most severe cyclones recorded in the southern hemisphere (Category 5 cyclone Winston). We assessed the impacts of cyclone Winston on the coral reef habitat and fish assemblages in Kubulau and Levuka districts in Fiji. Wave modelling showed that cyclone-generated waves were substantially larger and persisted longer in Levuka than Kubulau. Damage to live corals was spatially variable and highest in Levuka, with the extent of damage highly correlated to the exposure, height and duration of waves at each site. We recorded increases in macroalgae directly after the cyclone and increases in encrusting coralline algae two years after the cyclone. We did not detect many changes in the fish assemblage caused by cyclone Winston. Obligate corallivores, and species within this group, Chaetodon baronessa and Labrichthys unilineatus, were the only fish to show a decline post-cyclone, most likely caused by declines in coral cover. We found that the modelling of cyclone wave dynamics (wave height, duration and exposure) explained the variation and damage to live corals better than proximity to the cyclone path, providing a useful tool to predict cyclone damage. Future climate models predict that more cyclones will reach the highest intensities. Understanding the impact this will have on vulnerable coastal communities that are dependent on marine resources and are protected from wave energy by reefs is essential for effective mitigation and adaptive management plans. [ABSTRACT FROM AUTHOR]

All residents (100%) and most attendings (96%) believed that patients would like to be able to access MAB in their primary care clinic. Medication abortion (MAB) is a safe and effective means of ending intrauterine pregnancy at <=10 weeks gestation and can safely be performed in the primary care setting[1]. [Extracted from the article]

The contribution of carbon fiber reinforced polymer (CFRP) wrap as an anchorage system of CFRP plates, used for flexural strengthening, is investigated. Eighteen concrete beams (100 × 150 × 1400 mm3) were cast and cured for 28 days before strengthening with both CFRP plates (1.2 × 50 mm2) and anchorage-used, U-shaped CFRP wraps. These were adhered on the top of the CFRP plates at different longitudinal and transverse extensions. The mechanical response of the concrete beams was examined under four-point loading including measurements of load versus deflection, bond stress versus slippage and strain in CFRP plates. Crack formation and failure modes were also monitored and characterized. End anchorage regimes, using 300-mm-long U-shaped segmented CFRP wraps, impart the best improvement to load capacity, rigidity, and toughness (up to 80, 57, and 40%, respectively) without harming tangibly ductility in terms of deflection at failure. Anchorage cases involving attaching continuous single or double layers of U-shaped CFRP wrap on the top of CFRP plates impart lower but tangible overall improvements in mechanical performance of CFRP-strengthened beams. A simple empirical model is developed to predict ultimate strain in CFRP plate based on present results before examining using available literature data. Moreover, the efficiency of the present technique is compared to that present in literature. [ABSTRACT FROM AUTHOR]

Hydraulic fracturing is the prime technology for enhancing production from unconventional reservoirs. Design and operation of hydraulic fracturing requires adequate knowledge of formation properties, in situ stresses and fluid properties, due to its complex nature. One of the challenges, that have been the subject of many past studies, is the interaction mechanism when hydraulic fracture intersects a natural interface (e.g., natural fracture or interbed). Crossing, arresting and opening are the known interaction mechanisms. The formation properties, state of in situ stresses, stress contrast, strength properties of the interface, angle of intersection and injecting fluid characteristics affect the interaction mechanism to different extents. The use of numerical models is widespread in simulation of hydraulic fracturing. The use of methods based on the continuum (e.g., FEM) and discontinum (e.g., DEM) representation of media is subjected to some limitations in predicting the correct geometry of the propagating fracture. Lattice method, which is based on the bonded particle approach, has shown promise in simulating hydraulic fracturing. In this paper, lattice modeling is used to simulate the interaction mechanism of lab experiments carried out on mortar samples but at larger scales. The cubical mortar samples of 10 cm size had two synthetically built natural fractures with different angles of approach and filled with different types of glue. The effect of intersection angle and the mechanical properties of the interface were simulated numerically under conditions of viscosity-dominated fracture propagation regime as occurred in the lab. The results demonstrate the advantages of lattice simulation to study the impact of each parameter on the fracture interaction. A larger angle of approach and stronger glues are shown to promote the crossing mode. The shear strength and stress anisotropy are the main parameters influencing the interaction mechanism. [ABSTRACT FROM AUTHOR]

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Underground coal gasification (UCG) is an energy production pathway in underground coal deposits with the potential advantage of decreasing the greenhouse gas emissions during the energy extraction process. The environmental benefits of UCG are mainly due to eliminating (i) conventional mining operations, (ii) the presence of coal miners in the underground, (iii) coal washing and fines disposal, and (iv) coal stockpiling and coal transportation activities. Furthermore, UCG has a capacity of great potential to provide a clean coal energy source by the implementing carbon capture and storage techniques as part of the energy extraction process. In this method, coal seams in the underground were converted into syngas including hydrogen (H2), carbon monoxide (CO), carbon dioxide (CO2), and methane (CH4) gasses with an advanced thermochemical process. UCG operation effected significant geomechanical changes to the overburden strata. In this process, the vertical well (especially the production well) was mainly affected by the mechanical stresses and the thermal stress, induced by the high syngas temperature. This high temperature changed the mechanical, thermal, and physical properties of the coal seam and its surrounding rocks (the host rocks), finally causing instability of the vertical well, while leading to serious production and environmental problems. One of these environmental issues is the possibility of syngas leakage in to the environment, resulting in water pollution and acidification. In addition, the released syngas could trigger global warming and air pollution. This research evaluated environmental aspects of UCG vertical well (production well) based on the stability analysis. Therefore, a flow sheet form was developed for three-dimensional thermomechanical numerical modeling of an UCG vertical well by explicit Lagrangian finite difference method. In this model, a criterion was established based on normalized yielded zone area to assess the stability conditions. The methodology was able to capture all factors that influence the instability of UCG well while selecting suitable mud pressure and lining system during the well drilling process. Hence, when wellbore integrity issues arose during drilling, the mitigation strategies were applied to rectify these problems. The results demonstrated that the vertical well should be drilled at a constant mud pressure of 9 MPa (megapascal), thus causing minimum environmental problems. The thermomechanical modeling provided an opportunity to assess the potential environmental impacts and identify reliable global climate change mitigation strategies. [ABSTRACT FROM AUTHOR]

Objectives To examine the association between intensity of home visits in early intervention (EI), perceived helpfulness of home visits in EI, and positive family relationships as predictors of maternal competence at age 3, as well as moderating effects of predictors, controlling for child characteristics, family demographics, and negative life events. Methods Data were drawn from the Early Intervention Collaborative Study (EICS), a 24-year longitudinal investigation of approximately 190 families of children with developmental disabilities who participated in EI programs in Massachusetts and New Hampshire. The primary analytic strategy was multivariable regression modeling. Each independent predictor was tested individually and then all together to build the final model. Interactions between independent predictors were also examined. Results After controlling for child and family characteristics and negative life events, the intensity of home visits was not significantly associated with maternal competence at age 3. However, the helpfulness of home visits (β = 2.94, S.E. = 1.12, p < .01) and positive family relationships (β = 5.11, S.E. = 1.08, p < .001) were associated with higher maternal competence when the child was 3 years old. Conclusions for Practice Recommendations for programs and policy include collecting life course data on families, particularly on their family relationships and experiences in EI and home visiting, assessing family relationships at the beginning of EI using a strengths-based perspective, and closely monitoring the quality of services. [ABSTRACT FROM AUTHOR]

TMPRSS2/ERG fusion was found to be the most common genetic event in prostate adenocarcinoma. There is a strong correlation between the fusion and ERG-positive immunostaining. Many studies showed racial variation in ERG expression in prostate cancer patients. There is no data however on the rate of ERG-positive cancer in Jordanian or Arab population. We evaluated the frequency and the significance of ERG fusion in Jordanian-Arab population using immunohistochemistry for ERG. The cohort included 193 prostate cancer specimens: 109 needle core biopsies, 45 radical prostatectomies, 37 transurethral resections of prostate, and 2 enucleation specimens. We found ERG reactivity in 64 (33.2%) of evaluated cases. The observed ERG frequency in the Jordanian-Arab population is lower than the one documented in North America, but it is higher than in Asian patient cohorts. The ERG positivity was significantly associated with lower baseline prostate-specific antigen but was unrelated to patient age, Gleason Score, or the novel Gleason Grade Groups. In the 45 prostatectomy cases, ERG did not correlate with the pathologic stage, margin, nodal status, and the biochemical recurrence, and it did not appear to represent an important prognosticator. [ABSTRACT FROM AUTHOR]

Attitudes of health professionals towards patients with addiction continues to be negative, which is increasingly recognized as a major barrier to the receipt of optimal clinical care by those patients. This study aims to describe nurses' attitudes and the underlying factors influencing nurses' attitudes towards patients in two addiction rehabilitation centers in Jordan. Employing a case study design, using ethnographic fieldwork, we collected data from a purposive sample of twenty-one clinical nurses, using semi-structured interviews, which were analyzed for themes derived from the literature. Negative nurses' attitudes towards 'addicted' patients ranged from stigmatization, marginalization, avoidance of patients, to class discrimination. Major socio-cultural factors (honor-gender-shame triad, socialization process, mass media, perceiving addiction as a 'hopeless' condition), and other contributory factors played a role in constructing nurses' negative attitudes. We recommend a nursing curriculum that includes education regarding addiction behavioral patterns, and a continuing education regarding patients' rights, legal and ethical aspects of nursing care. [ABSTRACT FROM AUTHOR]

Production of hydrocarbons from shale formations has been made possible mainly due to hydraulic fracture (HF) technology. It increases the permeability of reservoir rocks around a well by connecting fractures and improving conductivity. HF behavior especially in presence of natural fractures have recently given much attention in studies. This paper investigates HF propagation and its associated parameters in various conditions. A higher order displacement discontinuity method is used to achieve higher accuracy in the results. First, behavior of crack opening displacement (COD) of an HF i.e. HF width in various conditions is studied. COD is a key parameter in determination of an HF operation success. It is proportional to production rate of oil and gas wells and provides a path for proppant entrance into the fractures. An equation considering many important parameters, based on numerous numerical modellings of various mechanical and geometrical effects on COD is proposed with coefficient of determination and standard error of 94.35% and 4.37 × 10 respectively. The next part of the paper studies the HF propagation in a naturally fractured reservoir. These natural fractures alter the stress fields and hence affect the propagation of a hydraulic fracture. In fact, it is shown that in certain orientations of hydraulic fractures and natural fractures, the effect of natural fractures disappear or completely changes propagation path. Using a combination of several interaction criteria, a new modeling of HFs and NFs interaction is presented. The modellings showed that spacing and angle of intersection can significantly affect HFs propagation. The results of COD and HF propagation in presence of natural fractures may be considered in HG design and primary orientation of perforated fractures. [ABSTRACT FROM AUTHOR]

Crack propagation process in pre-cracked rock like specimens has been studied experimentally and numerically considering three cracks in the middle part of each specimen. The rock-like specimens are specially prepared from Portland pozzolana cement, fine sands and water. These pre-cracked cylindrical specimens (each containing a single inclined crack in the neighborhood of two iso-path cracks) are experimentally tested under compressive loading. The same problems are numerically simulated by a modified displacement discontinuity method using higher order displacement discontinuity elements and higher order special crack tip elements for crack tip treatment to increase the accuracy of the Mode I and Mode II stress intensity factors obtained based on linear elastic fracture mechanics theory. The crack propagation and coalescence paths of the inclined crack are estimated by implementing a suitable iteration algorithm of incremental crack length extension in a direction predicted by using the maximum tangential stress criterion. The numerical and analytical crack extension analyses are compared which are in good agreement and show the validity, applicability and accuracy of the present work. [ABSTRACT FROM AUTHOR]

The higher order displacement discontinuity method (HODDM) utilizing special crack tip elements has been used in the solution of linear elastic fracture mechanics (LEFM) problems. The paper has selected several example problems from the fracture mechanics literature (with available analytical solutions) including center slant crack in an infinite and finite body, single and double edge cracks, cracks emanating from a circular hole. The numerical values of Mode I and Mode II SIFs for these problems using HODDM are in excellent agreement with analytical results (reaching up to 0.001% deviation from their analytical results). The HODDM is also compared with the XFEM and a modified XFEM results. The results show that the HODDM needs a considerably lower computational effort (with less than 400 nodes) than the XFEM and the modified XFEM (which needs more than 10000 nodes) to reach a much higher accuracy. The proposed HODDM offers higher accuracy and lower computation effort for a wide range of problems in LEFM. [ABSTRACT FROM AUTHOR]

A simultaneous experimental and numerical study of shear fracture of concrete-like materials is carried out using Brazilian disc specimens with initial double edge cracks and fourpoint bending beam specimens with double edge-notches. The interference effects of two cracks/notches are investigated through varied ligament angles and crack lengths. It is shown that shear fracturing paths change remarkably with the initial ligament angles and crack lengths. The cracked specimens are numerically simulated by an indirect boundary element method. A comparison between the numerical results and the experimental ones shows good agreement. [ABSTRACT FROM AUTHOR]

Many problems in subsurface rocks which are naturally filled with saturated cracks and pores (with one or more fluid phases) are better understood in a poroelastic framework. Displacement discontinuity method ( DDM) is particularly ideal for problems involving fractures and discontinuities. However, the DDM in its original form is limited to elastic problems. The paper derives fundamental solutions of a poroelastic DDM. Then introduces a numerical formulation and implementation for the poroelastic DDM in a code named constant element poroelastic DDM ( CEP-DDM). The accuracy and validity of the proposed solution and the newly developed code is verified by an analytical solution at short-time and long-time. Numerical results showed good agreement with analytical results at short time (undrained response) and long time ( $$t=8000$$ s) (drained response). A crack propagation scheme for crack propagation problems is introduced and demonstrated in an example which enables the code to follow crack propagation in time and space. [ABSTRACT FROM AUTHOR]

Crack propagation processes in specially prepared concrete discs and rectangular specimens containing a single cylindrical hole or multiple holes of varying diameters have been studied both experimentally and numerically. In this research, the cracks coalescence paths in Brazilian disc and rectangular specimens made from rock-like material containing multi-holes are investigated. These concrete specimens are specially prepared from an appropriate mixture of Portland Pozzolana Cement (PPC), fine sands, and water. The pre-holed Brazilian discs and rectangular specimens are experimentally tested under compression. The breakage load in the ring type disc specimens containing an axial hole with varying diameters is measured and the distribution of the induced lateral stress is obtained. The mechanism of cracks propagation in the wall of the ring type specimens is also studied. In the case of multi-hole Brazilian disc and rectangular specimens, the cracks propagation and cracks coalescence are also investigated. These experiments are numerically modeled by a modified higher order displacement discontinuity method. It has been shown that the corresponding experimental and numerical results are in good agreement with each other. The results presented in this research validate the accuracy and applicability of these crack analyses procedures. [ABSTRACT FROM AUTHOR]

Rocks and rock-like materials frequently fail under compression due to the initiation, propagation and coalescence of the pre-existing microcracks. The mechanism of microcrack coalescence process in rock-like materials is experimentally and numerically investigated. The experimental study involves some uniaxial compression tests on rock-like specimens specially prepared from portland pozzolana cement, mica sheets and water. The microcrack coalescence is studied by scanning electron microscopy on some of the prepared thin specimens. It is assumed that the mica sheets play the role of microcracks within the specimens. Some analytical and numerical studies are also carried out to simulate the experimentally observed microcrack coalescence phenomena within the specimens. A higher-order indirect boundary element method known as higher-order displacement discontinuity method implementing special crack tip elements to treat the singularities of stress and displacement fields near the crack ends is used to estimate the Mode I and Mode II stress intensity factors at the microcrack tips. The maximum tangential stress fracture criterion is implemented in a sophisticated computer code using the linear elastic fracture mechanics theory and the propagation and coalescence of random microcracks within the rock-like specimens are numerically simulated based on an iterative algorithm. The proposed analyses are validated by comparing the corresponding experimental and numerical results of microcrack coalescence phenomena of rock-like materials. [ABSTRACT FROM AUTHOR]

In this research, a coupled numerical-experimental analysis of crack propagation, crack coalescence, and breaking process of jointed rock slopes is performed by studying the mechanical behavior of pre-cracked brittle substances considering the specially prepared rock-like specimens (rock-like specimens are specially prepared by a proper mixing of Portland Pozzolana Cement (PPC), fine sand, and water in a rock mechanics laboratory) and natural rock slopes, simultaneously. The numerical analyses are accomplished using a numerical code based on the higher-order displacement discontinuity method (HODDM). A cubic displacement discontinuity variation along each boundary element is assumed to evaluate the mode I and mode II stress intensity factors (SIFs). Based on the LEFM theory, the maximum tangential stress criterion is implemented in the proposed code for predicting the crack initiation and its direction of propagation (crack coalescence path). Experimental tests are accomplished to evaluate the crack propagation process, crack coalescence, and final breakage path of rock-like specimens containing three parallel cracks (simulating the natural joint set in a rock slope). There is a good agreement between the numerical and experimental results obtained from the tested specimens demonstrating the accuracy and effectiveness of the proposed approach. [ABSTRACT FROM AUTHOR]

The pre-cracked Brazilian disc specimens of rock-like materials (Portland Pozzolana cement (PPC), fine sands, and water) are especially prepared in a rock mechanics laboratory to study the breaking process of brittle solids. The Brazilian discs may contain one, two, three, four, and five (parallel) center slant cracks (45° to the horizontal) under compressive line loading. The breaking load of the pre-cracked disc specimens is measured showing that as the number of cracks increases, the final breakage load of the specimen decreases. The experiments are carried out under compression (just like the Brazilian tests used for measuring the indirect tensile strength of intact rocks). It has been experimentally observed that the wing cracks are produced at the first stage of loading and start their propagation toward the direction of compressive line loading in the pre-cracked Brazilian discs. The same specimens are numerically simulated by a higher order displacement discontinuity method (HDDM). The effect of bridge area and orientation of cracks on the cracks coalescence and breakage path of the pre-cracked Brazilian discs specimens are simultaneously studied. [ABSTRACT FROM AUTHOR]

In this study, the displacement discontinuity formulation is used to solve the problem of interaction between hydraulic fractures (HF) and natural fractures (NF). Furthermore, a numerical program (2DFPM) is developed to study the mechanical activation of a NF because of the propagation of the HF. The accuracy of the numerical method is enhanced using the higher-order displacement variation along the HF and the special crack tip element near its ends. The maximum tangential stress criterion is implemented to predict the HF propagation path, and the stages of hydraulic fracturing tip approaching, coalescence and fluid penetration along the NF are modeled. The tangential stress around the NF with different contact modes (bonded, sliding and opening) is calculated by coupling the finite difference and boundary element methods. The location of secondary tensile fracture that re-initiates along the opposite side of NF is determined, and the key parameters that have great influence on interaction process are discussed. The results show that position, distance and inclination of the HF relative to the pre-existing discontinuity have a strong influence on the HF propagation path. [ABSTRACT FROM AUTHOR]

We conducted in-depth case studies of 10 health care professionals who actively provide primary medical care to adults with autism spectrum disorders. The study sought to understand their experiences in providing this care, the training they had received, the training they lack and their suggestions for encouraging more physicians to provide this care. Qualitative data were gathered by phone using a structured interview guide and analyzed using the framework approach. Challenges to providing care were identified at the systems, practice and provider, and education and training levels. Solutions and interventions targeting needed changes at each level were also proposed. The findings have implications for health care reform, medical school and residency training programs, and the development of best practices. [ABSTRACT FROM AUTHOR]

Underground excavation in rocks can be accomplished in several steps. The cutting action of mechanical tools such as disc cutters used in tunnel boring machines (TBM) is one of the most basic steps. Indentation of TBM disc cutters into the rock can produce rock chips in different scales. This phenomenon involves the production of micro cracks, their propagating, and coalescing process to form macro cracks. The present research focuses on the concepts of linear elastic fracture mechanics (LEFM) and maximum tangential stress criterion to investigate the micro crack propagation and its direction of growth in rocks underneath the TBM disc cutters. A modified higher order semi-infinite displacement discontinuity method (HSDDM) with third order displacement discontinuity elements (cubic elements) is used to estimate the stress intensity factor in the fractured rocks underneath a single disc cutter. To reduce the errors caused by stress and displacement singularities near the crack tip, three special crack tip elements have been implemented in the HSDDM computer code. TBM disc cutters will be eroded after a period of working. Therefore, the numerical simulation of eroded and not eroded discs has been proposed in this study. To simulate the eroded disc, four small elements have been modeled to generate the curvature of the cutter tip, which in turn reduces the cutting efficiency and increases required specific energy for a typical disc cutter. [ABSTRACT FROM AUTHOR]

Micro cracks in brittle materials seem to be the main cause of their breakage under various loading conditions. In the present paper, the numerical and experimental analyses of initiation, propagation, and coalescence of micro cracks have been investigated. A higher order displacement discontinuity method with special crack tip elements is used to estimate the mixed-mode (mode I and mode II) stress intensity factors near the tips of the preexisting micro cracks. The propagation direction of micro cracks is estimated by using the maximum tensile stress criterion which is based on the linear elastic fracture mechanics concept. Some experiments are also carried out to observe the crack coalescence and crack propagation path of micro cracks. These experiments also verify the validity of the numerical results. For example, the crack initiation angles obtained numerically are compared with the corresponding experimental results showing the validity of these numerical results. Some of the numerical and experimental results are also compared with the corresponding results given in the literature. [ABSTRACT FROM AUTHOR]

The present research is focused on the numerical crack coalescence analysis of the micro-cracks and cracks produced during the cutting action of TBM disc cutters. The linear elastic fracture mechanics (LEFM) concepts and the maximum tangential stress criterion are used to investigate the micro crack propagation and its direction underneath the excavating discs. A higher order displacement discontinuity method with quadratic displacement discontinuity elements is used to estimate the stress intensity factors near the crack tips. Rock cutting mechanisms under single and double type discs are simulated by the proposed numerical method. The main purposes of the present modeling are to simulate the chip formation process of indented rocks by single and double discs. The effects of specific disc parameters (except speed) on the thrust force F, the rolling force F, and the specific energy E are investigated. It has been shown that the specific energy (energy required to cut through a unit volume of rock) of the double disc is less than that of the single disc. Crack propagation in rocks under disc cutters is numerically modeled and the optimum ratio of disc spacing S to penetration depth P (i.e. S/ P ratio) of about 10 is obtained, which is in good agreement with the theoretical and experimental results cited in the literature. [ABSTRACT FROM AUTHOR]

Pre-existing cracks in brittle substances seem to be the main cause of their breakage under various loading conditions. In the present paper, a coupled numerical-experimental analysis of crack propagation, cracks coalescence, and breakage process of brittle substances such as rocks and rock-like samples have been studied. The numerical analyses are accomplished using a numerical code based on the Higher order Displacement Discontinuity Method for Crack (HDDMCR) analysis. A quadratic displacement discontinuity variation along each boundary element is assumed to evaluate the Mode I and Mode II stress intensity factors. Based on the linear elastic fracture mechanics theory, the maximum tangential stress criterion (i.e., a mixed mode fracture criterion) is implemented in the HDDMCR code for predicting the crack initiation and its direction of propagation (cracks propagation path). Some numerical and analytical problems in finite and infinite planes are solved numerically by the proposed numerical method, and the results are compared in different tables illustrating the accuracy and validity of the numerical results. Experimental tests are also being done to evaluate the final breakage path and cracks initiation and cracks coalescence stresses in rock-like specimens containing two random cracks. The numerical and experimental results obtained from the tested specimens show a good agreement between the corresponding values and demonstrate the accuracy and effectiveness of the approach. [ABSTRACT FROM AUTHOR]