3,024 research outputs found

    Heating temperature prediction of concrete structure damaged by fire using a Bayesian approach

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    A fire that occurs in a reinforced concrete (RC) structure accompanies a heating temperature, and this negatively affects the concrete material properties, such as the compressive strength, the bond between cement paste and aggregate, and the cracking and spalling of concrete. To appropriately measure the reduced structural performance and durability of fire-damaged RC structures, it is important to accurately estimate the heating temperature of the structure. However, studies in the literature on RC structures damaged by fire have focused mostly on structural member tests at elevated temperatures to ensure the fire resistance or fire protection material development; studies on estimating the heating temperature are very limited except for the very few existing models. Therefore, in this study, a heating temperature estimation model for a reinforced concrete (RC) structure damaged by fire was developed using a statistical Bayesian parameter estimation approach. For the model development, a total of 77 concrete test specimens were utilized; based on them, a statistically highly accurate model has been developed. The usage of the proposed method in the framework of the 500 ◦C isotherm method in Eurocode 2 has been illustrated through an RC column resistance estimation application

    Factors Influencing on Sexual Assertiveness of College Students

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    PURPOSE: The purpose of this study was to identify the factors influencing sexual assertiveness in dating college students. METHODS: With a cross-sectional survey design, 468 college students who have had dating experiences were recruited and answered questionnaires. Data were analyzed using t-test, ANOVA with Scheffe? test, Pearson's correlation coefficients, and multiple regression. RESULTS: The sexual assertiveness of college students showed significant results: positive correlations with self-assertiveness and negative correlations with traditional sexual attitude, gender role stereotypes. Significant predictors of sexual assertiveness were traditional sexual attitude, gender role stereotypes, and self-assertiveness. These variables explained 37% of the variance in sexual assertiveness. CONCLUSION: Findings suggest that it is important to identify and improve communication patterns in relation to sexual assertiveness. There is a need for sex education programs for college students that are relevant and effective

    Vav1 inhibits RANKL-induced osteoclast differentiation and bone resorption

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    Vav1 is a Rho/Rac guanine nucleotide exchange factor primarily expressed in hematopoietic cells. In this study, we investigated the potential role of Vav1 in osteoclast (OC) differentiation by comparing the ability of bone marrow mononuclear cells (BMMCs) obtained from Vav1-deficient (Vav1−/−) and wild-type (WT) mice to differentiate into mature OCs upon stimulation with macrophage colony stimulating factor and receptor activator of nuclear kappa B ligand in vitro. Our results suggested that Vav1 deficiency promoted the differentiation of BMMCs into OCs, as indicated by the increased expression of tartrate-resistant acid phosphatase, cathepsin K, and calcitonin receptor. Therefore, Vav1 may play a negative role in OC differentiation. This hypothesis was supported by the observation of more OCs in the femurs of Vav1−/− mice than in WT mice. Furthermore, the bone status of Vav1−/− mice was analyzed in situ and the femurs of Vav1−/− mice appeared abnormal, with poor bone density and fewer number of trabeculae. In addition, Vav1-deficient OCs showed stronger adhesion to vitronectin, an αvβ3 integrin ligand important in bone resorption. Thus, Vav1 may inhibit OC differentiation and protect against bone resorption

    Quantum Optical Induced-Coherence Tomography by a Hybrid Interferometer

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    Quantum interferometry based on induced-coherence phenomena has demonstrated the possibility of undetected-photon measurements. Perturbation in the optical path of probe photons can be detected by interference signals generated by quantum mechanically correlated twin photons propagating through a different path, possibly at a different wavelength. To the best of our knowledge, this work demonstrates for the first time a hybrid-type induced-coherence interferometer that incorporates a Mach-Zehnder-type interferometer for visible photons and a Michelson-type interferometer for infrared photons, based on double-pass pumped spontaneous parametric down-conversion. This configuration enables infrared optical measurements via the detection of near-visible photons and provides methods for characterizing the quality of measurements by identifying photon pairs of different origins. The results verify that the induced-coherence interference visibility is approximately the same as the heralding efficiencies between twin photons along the relevant spatial modes. Applications to both time-domain and frequency-domain quantum-optical induced-coherence tomography for three-dimensional test structures are demonstrated. The results prove the feasibility of practical undetected-photon sensing and imaging techniques based on the presented structure

    Properties of Central Caustics in Planetary Microlensing

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    To maximize the number of planet detections, current microlensing follow-up observations are focusing on high-magnification events which have a higher chance of being perturbed by central caustics. In this paper, we investigate the properties of central caustics and the perturbations induced by them. We derive analytic expressions of the location, size, and shape of the central caustic as a function of the star-planet separation, ss, and the planet/star mass ratio, qq, under the planetary perturbative approximation and compare the results with those based on numerical computations. While it has been known that the size of the planetary caustic is \propto \sqrt{q}, we find from this work that the dependence of the size of the central caustic on qq is linear, i.e., \propto q, implying that the central caustic shrinks much more rapidly with the decrease of qq compared to the planetary caustic. The central-caustic size depends also on the star-planet separation. If the size of the caustic is defined as the separation between the two cusps on the star-planet axis (horizontal width), we find that the dependence of the central-caustic size on the separation is \propto (s+1/s). While the size of the central caustic depends both on ss and q, its shape defined as the vertical/horizontal width ratio, R_c, is solely dependent on the planetary separation and we derive an analytic relation between R_c and s. Due to the smaller size of the central caustic combined with much more rapid decrease of its size with the decrease of q, the effect of finite source size on the perturbation induced by the central caustic is much more severe than the effect on the perturbation induced by the planetary caustic. Abridged.Comment: 5 pages, 4 figures, ApJ accepte

    Erratum: Correction of Title. Literature Review on Intervention for Breast Cancer Survivors and Their Partners

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    We found an title error in our published article

    Factors Influencing Academic Self-efficacy among Nursing Students during COVID-19: A Path Analysis

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    Introduction: The shift to online learning owing to the coronavirus disease 2019 pandemic is posing an additional challenge to academic success, particularly for students who speak English as a Second Language (ESL). This study aimed to examine the factors that contribute to academic self-efficacy among ESL nursing students. Method: This was a cross-sectional study using path analysis with 113 undergraduate ESL nursing students in New York City. Data were collected online using self-report measures of the study variables: academic self-efficacy, perfectionistic concerns, acculturative stress, and e-learning stress. A hypothetical path model was tested using AMOS 26.0. Results: Perfectionistic concerns and acculturative stress directly affected academic self-efficacy. Furthermore, perfectionistic concerns and e-learning stress indirectly affected academic self-efficacy via the acculturative stress path. Discussion: Results indicate the importance of developing a multifaceted intervention that considers diverse cultural and psychological factors to help ESL nursing students enhance their academic self-efficacy in e-learning environments

    Sustainable forest management for nut and fuelwood production in the Jalalabad region, Kyrgyzstan: insights from local communities

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    Jalalabad region in the Kyrgyz Republic is home to the world’s largest natural walnut (Juglans regia L.) forests and pistachio (Pistacia vera L.) forests. These nut-fruit forests serve as the primary source of income for local people; however, deforestation has led to a decline in the availability of these resources. Wood from the forest is also used as a crucial energy source for cooking and heating in this region, despite state protection of the walnut forest due to a lack of alternative energy sources. This study aimed to explore solutions to restore nut-fruit forests while providing a fuelwood source and improving the income of local people. Qualitative research methods were employed, including semi-structured interviews and survey questionnaires with farmers and central and local government officials. The study investigated the main environmental problem of forest degradation and the challenges of forest management, such as livestock and complicated lease arrangements, and determined possible government support and incentives for local communities to participate in forest rehabilitation, such as planting instead of paying lease fees. The findings indicated that a tree-based farming approach can be a promising alternative land-use solution. Seventy-four percent of local farmers expressed their readiness to plant fruit trees and fast-growing tree species to meet their demand for fuelwood and improve their livelihoods if the government can provide temporary fencing support. The study also highlighted the need for capacity building for farmers to learn proper planting, managing, and harvesting for more sustainable practices. Policymakers need to modify legislation through simplified and incentive-based forest lease arrangements

    Transport properties of graphene with one-dimensional charge defects

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    We study the effect of extended charge defects in electronic transport properties of graphene. Extended defects are ubiquitous in chemically and epitaxially grown graphene samples due to internal strains associated with the lattice mismatch. We show that at low energies these defects interact quite strongly with the 2D Dirac fermions and have an important effect in the DC-conductivity of these materials.Comment: 6 pages, 5 figures. published version: one figure, appendix and references adde
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