Cyclic Crack Monitoring of a Reinforced Concrete Column under Simulated Pseudo-Dynamic Loading Using Piezoceramic-Based Smart Aggregates

Structural health monitoring is an important aspect of maintenance for bridge columns in areas of high seismic activity. In this project, recently developed piezoceramic-based transducers, known as smart aggregates (SA), were utilized to perform structural health monitoring of a reinforced concrete (RC) bridge column subjected to pseudo-dynamic loading. The SA-based approach has been previously verified for static and dynamic loading but never for pseudo-dynamic loading. Based on the developed SAs, an active-sensing approach was developed to perform real-time health status evaluation of the RC column during the loading procedure. The existence of cracks attenuated the stress wave transmission energy during the loading procedure and reduced the amplitudes of the signal received by SA sensors. To detect the crack evolution and evaluate the damage severity, a wavelet packet-based structural damage index was developed. Experimental results verified the effectiveness of the SAs in structural health monitoring of the RC column under pseudo-dynamic loading. In addition to monitoring the general severity of the damage, the local structural damage indices show potential to report the cyclic crack open-close phenomenon subjected to the pseudo-dynamic loading

Cure-state monitoring of concrete and mortar specimens using Smart Aggregates

This paper experimentally studies the measurement of stress wave transmission properties in early-age concrete and mortar slab specimens. The studies are enabled by embedded piezoelectric-based transducers called “Smart Aggregates (SAs)” that generated and received a swept sine stress wave in the specimens at frequency range of 100 Hz – 150 kHz. Dependencies of the resonant peak amplitude and frequency of power spectrum density as transmission energy indicator on water-to-cement (w/c) ratio and effect of coarse aggregates in the specimens are demonstrated. It is shown that the changes of the resonant resonance peak have different rates for the concrete and mortar specimens with different w/c ratios when the hydration process proceeded. The potential of SAbased cure-state monitoring method for very early-age concrete assessment is discussed

Characterization of cement concrete specimens during hydration process with piezoelectric-based smart aggregates

Characterization of cement concrete during hydration process has been performed using different methods. The determination of initial water-to-cement ratio is one of the challenging tasks since hydration process determines the microstructure of cement concrete and non-destructive methods with high accuracy are desired. This paper presents the results of the investigation into the stress wave transmission in cement concrete specimens with different initial water amount during hydration process. A non-destructive evaluation approach using embedded Smart Aggregates (SAs) at frequency range of 150 Hz to 150 kHz is used for this purpose. In this approach, one SA acts as an actuator when the swept sinusoidal wave is excited. The stress wave transmits through the specimen and it partially is received by the SA sensor. The time-domain receiving signals are recorded during hydration process and the corresponding power spectrum densities as transmission energy are computed and analysed, and then used for the material characterization. In addition, a destructive compression test is carried out on the 7th day and 28th day. The results show that changes of water amount in the standard-based specimens reduce their stress wave transmission performance and compressive strength value at 28th day. The feasibility of the SAs technique for the determination of water-to-cement ratio of cement concrete is also demonstrated

Current patient perspectives of vulvovaginal candidiasis: incidence, symptoms, management and post-treatment outcomes

Abstract Background Vulvovaginal candidiasis (VVC) is a common infection affecting women worldwide. Reports of patterns/risk factors/trends for episodic/recurrent VVC (RVVC) are largely outdated. The purpose of this study was to obtain current patient perspectives of several aspects of VVC/RVVC. Methods Business cards containing on-line survey information were distributed to healthy volunteers and patients seeking standard, elective, or referral gynecologic care in university-affiliated Obstetrics/Gynecology clinics. The internet-based questionnaire was completed by 284 non-pregnant women (78% Caucasian, 14% African American, 8% Asian). Results The majority of the participants (78%) indicated a history of VVC with 34% defined as having RVVC. The most common signs/symptoms experienced were itching, burning and redness with similar ranking of symptoms among VVC and RVVC patients. Among risk factors, antibiotic use ranked highest followed by intercourse, humid weather and use of feminine hygiene products. A high number of respondents noted ‘no known cause’ (idiopathic episodes) that was surprisingly similar among women with a history of either VVC or RVVC. VVC/RVVC episodes reported were primarily physician-diagnosed (73%) with the remainder mostly reporting self-diagnosis and treating with over-the-counter (OTC) medications. Most physician-diagnosed attacks utilized a combination of pelvic examination and laboratory tests followed by prescribed antifungals. Physician-treated cases achieved a higher level of symptom relief (84%) compared to those who self-medicated (57%). The majority of women with RVVC (71%) required continual or long-term antifungal medication as maintenance therapy to control symptoms. Conclusions Current patient perspectives closely reflect historically documented estimates of VVC/RVVC prevalence and trends regarding symptomatology, disease management and post-treatment outcomes

RAG-1 and Ly6D Independently Reflect Progression in the B Lymphoid Lineage

<div><p>Common lymphoid progenitors (CLPs) are thought to represent major intermediates in the transition of hematopoietic stem cells (HSCs) to B lineage lymphocytes. However, it has been obvious for some time that CLPs are heterogeneous, and there has been controversy concerning their differentiation potential. We have now resolved four Flt3⁺ CLP subsets that are relatively homogenous and capable of forming B cells. Differentiation potential and gene expression patterns suggest Flt3⁺ CLPs lacking both Ly6D and RAG-1 are the least differentiated. In addition to B cells, they generate natural killer (NK) and dendritic cells (DCs). At the other extreme is a subset of the recently described Flt3⁺ Ly6D⁺ CLPs that have a history of RAG-1 expression and are B lineage restricted. These relatively abundant and potent CLPs were depleted within 48 hours of acute <i>in vivo</i> estrogen elevation, suggesting they descend from hormone regulated progenitors. This contrasts with the hormone insensitivity of other CLP subsets that include NK lineage progenitors. This progenitor heterogeneity and differentiation complexity may add flexibility in response to environmental changes. Expression of RAG-1 and display of Ly6D are both milestone events, but they are neither synchronized nor dependent on each other.</p></div