Unified approach to crack growth and fracture

Unified approach connects the behavior of a smooth specimen, of a notched specimen and of the fracture-mechanics specimen, under inert and corrosive environments, using the unifying principles and the Modified Kitagawa-Takahashi Diagram. The unifying principles are based on the fact that the behavior of short cracks is not different from that of long cracks, and the same thresholds govern the crack growth. Cracks being high energy defects, local internal stresses are required to initiate and grow the cracks in all cases. The internal stresses can be pre-existing as in the case of long cracks or in situ generated or augmented in the case of smooth and notched specimens. Observed variations in the crack growth rates of short cracks from those of long cracks arise due to variations in the types and degrees of pre-existing internal stresses. In aggressive environments, chemical forces provide additional driving forces over and above the mechanical forces. Chemical forces come from the chemical and/or electro chemical potential gradients which may be difficult to determine as they depend on the nature and the extent of the local chemical reactions in the changing compositional gradients. From practical considerations, we show that they can be quantified using the inert medium as a reference. Cyclic loads provides additional factors since crack tip driving forces come from both monotonic and cyclic loads leading to load-ratio R dependence. We provide here a systematic analysis of these factors using our Unified Approach to help in quantification and codification of the kinetics of the crack growth and fracture

Initiation and growth of corrosion fatigue cracks from corrosion pits using elasto-plastic notch analysis

Corrosion pits are known to act as precursors for fatigue crack initiation under corrosive environment. The transition from pit to crack growth under corrosion fatigue is of considerable interest for many engineering structures. Several predictive methodologies have been developed. As the Pits grow with large aspect ratio, they behave like local stress/strain concentrations accentuating the crack initiation and growth. In this paper, we extend our recent analysis of crack initiation at the elastic-plastic notch tip stress fields* to evaluate its applicability to pit to crack transition. Ref: K. Sadananda, A. Arcari, A.K. Vaudevan, Eng. Frac. Mech., 2017, 176 pp.144-16

Association of Chlamydia pneumoniae IgG and IgA antibody in coronary artery disease

Background:Cardiovascular disease, resulting from atherosclerosis, is a leading cause of global morbidity and mortality. Classical risk factors explain much of the attributable risk for cardiovascular events, but other risk factors for the development and progression of atherosclerosis, which can be identified, may be important therapeutic targets. Infectious agents, such as Chlamydia pneumoniae, have been proposed as contributory factors in the pathogenesis of atherosclerosis. The present study was conducted to determine the seroprevalence of C. pneumoniae antibodies and to study the association of chronic C. pneumoniae infection with Coronary Artery Disease (CAD).Methods:The study group included 90 angiographically proven CAD patients and age and sex matched 90 normal coronaries as control group. With total aseptic precaution 3 ml blood was collected. Enzyme linked immunosorbant assay was performed for all subjects to detect the presence of IgG and IgA antibodies to Chlamydia pneumoniae (Cp).  Results:IgG and IgA Cp antibodies were detected in 67.8% and 58.9% CAD patients compared to 45.6% and 11.1%   controls. IgG + IgA Cp antibodies were detected in 88.9% CAD patients when compared to 50.0% controls. Seroprevalence of IgG and IgA Cp antibodies were high among CAD patients compared to controls and was found statistically significant. A significant presence of Chlamydia pneumoniae antibodies was detected in smokers, diabetes mellitus, hypertension, and dyslipidemia.  Conclusion:In the present study, the seroprevalence of IgG and IgA Cp antibodies was found to be higher in CAD patients compared to controls. The present study supports the   association between Chlamydia pneumoniae infection and Coronary artery disease.

Neurophysiological modeling of bladder afferent activity in the rat overactive bladder model

The overactive bladder (OAB) is a syndrome-based urinary dysfunction characterized by “urgency, with or without urge incontinence, usually with frequency and nocturia”. Earlier we developed a mathematical model of bladder nerve activity during voiding in anesthetized rats and found that the nerve activity in the relaxation phase of voiding contractions was all afferent. In the present study, we applied this mathematical model to an acetic acid (AA) rat model of bladder overactivity to study the sensitivity of afferent fibers in intact nerves to bladder pressure and volume changes. The afferent activity in the filling phase and the slope, i.e., the sensitivity of the afferent fibers to pressure changes in the post-void relaxation phase, were found to be significantly higher in AA than in saline measurements, while the offset (nerve activity at pressure ~0) and maximum pressure were comparable. We have thus shown, for the first time, that the sensitivity of afferent fibers in the OAB can be studied without cutting nerves or preparation of single fibers. We conclude that bladder overactivity induced by AA in rats is neurogenic in origin and is caused by increased sensitivity of afferent sensors in the bladder wall

TRPV1 enhances the afferent response to P2X receptor activation in the mouse urinary bladder

Both TRPV1 and P2X receptors present on bladder sensory nerve fibres have been implicated in mechanosensation during bladder filling. The aim of this study was to determine possible interactions between these receptors in modulating afferent nerve activity. In wildtype (TRPV1+/+) and TRPV1 knockout (TRPV1−/−) mice, bladder afferent nerve activity, intravesical pressure, and luminal ATP and acetylcholine levels were determined and also intracellular calcium responses of dissociated pelvic DRG neurones and primary mouse urothelial cells (PMUCs). Bladder afferent nerve responses to the purinergic agonist αβMethylene-ATP were depressed in TRPV1−/− mice (p ≤ 0.001) and also in TRPV1+/+ mice treated with the TRPV1-antagonist capsazepine (10 µM; p ≤ 0.001). These effects were independent of changes in bladder compliance or contractility. Responses of DRG neuron to αβMethylene-ATP (30 µM) were unchanged in the TRPV1−/− mice, but the proportion of responsive neurones was reduced (p ≤ 0.01). Although the TRPV1 agonist capsaicin (1 µM) did not evoke intracellular responses in PMUCs from TRPV1+/+ mice, luminal ATP levels were reduced in the TRPV1−/− mice (p ≤ 0.001) compared to wildtype. TRPV1 modulates P2X mediated afferent responses and provides a mechanistic basis for the decrease in sensory symptoms observed following resiniferatoxin and capsaicin treatment for lower urinary tract symptoms

Precision sketching with de-aging networks in forensics

Addressing the intricacies of facial aging in forensic facial recognition, traditional sketch portraits often fall short in precision. This study introduces a pioneering system that seamlessly integrates a de-aging module and a sketch generator module to overcome the limitations inherent in existing methodologies. The de-aging module utilizes a deepfake-based neural network to rejuvenate facial features, while the sketch generator module leverages a pix2pix-based Generative Adversarial Network (GAN) for the generation of lifelike sketches. Comprehensive evaluations on the CUHK and AR datasets underscore the system’s superior efficiency. Significantly, comprehensive testing reveals marked enhancements in realism during the training process, demonstrated by notable reductions in Frechet Inception Distance (FID) scores (41.7 for CUHK, 60.2 for AR), augmented Structural Similarity Index (SSIM) values (0.789 for CUHK, 0.692 for AR), and improved Peak Signal-to-Noise Ratio (PSNR) metrics (20.26 for CUHK, 19.42 for AR). These findings underscore substantial advancements in the accuracy and reliability of facial recognition applications. Importantly, the system, proficient in handling diverse facial characteristics across gender, race, and culture, produces both composite and hand-drawn sketches, surpassing the capabilities of current state-of-the-art methods. This research emphasizes the transformative potential arising from the integration of de-aging networks with sketch generation, particularly for age-invariant forensic applications, and highlights the ongoing necessity for innovative developments in de-aging technology with broader societal and technological implications

Extravesicular TIMP-1 is a non-invasive independent prognostic marker and potential therapeutic target in colorectal liver metastases

Molecular reprogramming of stromal microarchitecture by tumour-derived extracellular vesicles (EVs) is proposed to favour pre-metastatic niche formation. We elucidated the role of extravesicular tissue inhibitor of matrix metalloproteinase-1 (TIMP1EV) in pro-invasive extracellular matrix (ECM) remodelling of the liver microenvironment to aid tumour progression in colorectal cancer (CRC). Immunohistochemistry analysis revealed a high expression of stromal TIMP1 in the invasion front that was associated with poor progression-free survival in patients with colorectal liver metastases. Molecular analysis identified TIMP1EV enrichment in CRC-EVs as a major factor in the induction of TIMP1 upregulation in recipient fibroblasts. Mechanistically, we proved that EV-mediated TIMP1 upregulation in recipient fibroblasts induced ECM remodelling. This effect was recapitulated by human serum-derived EVs providing strong evidence that CRC release active EVs into the blood circulation of patients for the horizontal transfer of malignant traits to recipient cells. Moreover, EV-associated TIMP1 binds to HSP90AA, a heat-shock protein, and the inhibition of HSP90AA on human-derived serum EVs attenuates TIMP1EV-mediated ECM remodelling, rendering EV-associated TIMP1 a potential therapeutic target. Eventually, in accordance with REMARK guidelines, we demonstrated in three independent cohorts that EV-bound TIMP1 is a robust circulating biomarker for a non-invasive, preoperative risk stratification in patients with colorectal liver metastases

External Urethral Sphincter Pressure Measurement: An Accurate Method for the Diagnosis of Detrusor External Sphincter Dyssynergia?

Combined pelvic floor electromyography (EMG) and videocystourethrography (VCUG) during urodynamic investigation are the most acceptable and widely agreed methods for diagnosing detrusor external sphincter dyssynergia (DESD). Theoretically, external urethral sphincter pressure (EUSP) measurement would provide enough information for the diagnosis of DESD and could simplify the urodynamic investigation replacing combined pelvic floor EMG and VCUG. Thus, we evaluated the diagnostic accuracy of EUSP measurement for DESD. PATIENTS #ENTITYSTARTX00026;A consecutive series of 72 patients (36 women, 36 men) with neurogenic lower urinary tract dysfunction able to void spontaneously was prospectively evaluated at a single university spinal cord injury center. Diagnosis of DESD using EUSP measurement (index test) versus combined pelvic floor EMG and VCUG (reference standard) was assessed according to the recommendations of the Standards for Reporting of Diagnostic Accuracy Initiative.Using EUSP measurement (index test) and combined pelvic floor EMG and VCUR (reference standard), DESD was diagnosed in 10 (14%) and in 41 (57%) patients, respectively. More than half of the patients presented discordant diagnosis between the index test and the reference standard. Among 41 patients with DESD diagnosed by combined pelvic floor EMG and VCUR, EUSP measurement identified only 6 patients. EUSP measurement had a sensitivity of 15% (95% CI 5%-25%), specificity of 87% (95% CI 76%-98%), positive predictive value of 60% (95% CI 30%-90%), and negative predictive value of 56% (95% CI 44%-68%) for the diagnosis of DESD.For diagnosis of DESD, EUSP measurement is inaccurate and cannot replace combined pelvic floor EMG and VCUR