Ductile fracture simulations using a multi-surface coupled damage-plasticity model

In this paper, an isotropic porous metal plasticity model accounting for both void growth by diffuse plastic deformation and void ‘coalescence’ by localization of plastic flow in the inter-void ligaments is presented. Predictions for the effective stress-strain response, evolution of damage and the strains to failure are obtained by integrating the model numerically under triaxial proportional loading conditions. The model predictions are compared with results from micromechanical finite element simulations of the average response of voided unit cells under similar loading conditions. It is shown that the model predictions for the failure strains as a function of the loading path are in good qualitative agreement with the results of the cell model simulations

Noise-robust method for image segmentation

Segmentation of noisy images is one of the most challenging problems in image analysis and any improvement of segmentation methods can highly influence the performance of many image processing applications. In automated image segmentation, the fuzzy c-means (FCM) clustering has been widely used because of its ability to model uncertainty within the data, applicability to multi-modal data and fairly robust behaviour. However, the standard FCM algorithm does not consider any information about the spatial linage context and is highly sensitive to noise and other imaging artefacts. Considering above mentioned problems, we developed a new FCM-based approach for the noise-robust fuzzy clustering and we present it in this paper. In this new iterative algorithm we incorporated both spatial and feature space information into the similarity measure and the membership function. We considered that spatial information depends on the relative location and features of the neighbouring pixels. The performance of the proposed algorithm is tested on synthetic image with different noise levels and real images. Experimental quantitative and qualitative segmentation results show that our method efficiently preserves the homogeneity of the regions and is more robust to noise than other FCM-based methods

A biophysical model of decision making in an antisaccade task through variable climbing activity

We present a biophysical model of saccade initiation based on competitive integration of planned and reactive cortical saccade decision signals in the intermediate layer of the superior colliculus. In the model, the variable slopes of the climbing activities of the input cortical decision signals are produced from variability in the conductances of Na+, K+, Ca2+ activated K+, NMDA and GABA currents. These cortical decision signals are integrated in the activities of buildup neurons in the intermediate layer of the superior colliculus, whose activities grow nonlinearly towards a preset criterion level. When the level is crossed, a movement is initiated. The resultant model reproduces the unimodal distributions of saccade reaction times (SRTs) for correct antisaccades and erroneous prosaccades as well as the variability of SRTs (ranging from 80ms to 600ms) and the overall 25% of erroneous prosaccade responses in a large sample of 2006 young men performing an antisaccade task

Self-managing postoperative pain with the use of a novel, interactive device: a proof of concept study

Background: Pain is commonly experienced following surgical procedures. Suboptimal management is multifactorial. Objectives. The primary objective was to assess whether patients used a device (Navimed) to self-report pain over and above a normal baseline of observations. Secondary outcome measures included comparison of pain scores and patient use of and feedback on the device. Methods: In a prospective randomized controlled trial, elective gynaecological surgery patients received standard postoperative pain care or standard care plus the Navimed, which allowed them to self-report pain and offered interactive self-help options. Results: 52 female patients, 26 in each of device and standard groups, did not differ in the frequency of nurse-documented pain scores or mean pain scores provided to nurses. The device group additionally reported pain on the device (means 18.50 versus 11.90 pain ratings per day, t(32) = 2.75, p < 0.001) that was significantly worse than reported to nurses but retrospectively rated significantly less anxiety. 80% of patients found the device useful. Discussion and Conclusion: This study demonstrates that patients used the Navimed to report pain and to help manage it. Further work is required to investigate the difference in pain scores reported and to develop more sophisticated software

Carotenoporphyrins as selective photodiagnostic agents for tumours.

The covalent binding of a carotene moiety to one phenyl ring and meso-tetraphenyl-substituted porphyrins (see Figure 1) efficiently quenches the photosensitising activity of the porphyrin while a relatively large yield of fluorescence emission around 650 nm is retained. Pharmacokinetic studies performed with two carotenoporphyrins (CPs) and the corresponding porphyrins (Ps) in Balb/c mice bearing an MS-2 fibrosarcoma show that the two Ps give a high selectivity of tumour localisation (tumour/peritumoral tissue ratios of dye concentration ranging between c. 30 and 90 at 24 h after injection of 4.2-8.4 mumol kg-1 in a Cremophor emulsion) and photosensitive tumour necrosis upon red light irradiation. For the same injected doses, the two CPs show no tumour-photosensitising activity even though they localise in the tumour in concentrations of the order of 10-40 micrograms g-1 at 24 h with tumour/peritumoral ratios larger than 10. Thus, the fluorescence emitted by these CPs in the tumour can be used for photodiagnostic purposes with no risk of skin photosensitisation. However, this approach is presently limited by the large accumulation and prolonged retention of the CPs in the liver and spleen

Characterization of Polyphosphoesters by Fourier Transform Ion Cyclotron Resonance Mass Spectrometry

FT-ICR mass spectrometry, together with collision-induced dissociation and electron capture dissociation, has been used to characterize the polyphosphoester poly[1,4-bis(hydroxyethyl)terephthalate-alt-ethyloxyphosphate] and its degradation products. Three degradation pathways were elucidated: hydrolysis of the phosphate–[1,4-bis(hydroxyethyl)terephthalate]bonds; hydrolysis of the phosphate–ethoxy bonds; and hydrolysis of the ethyl–terephthalate bonds. The dominant degradation reactions were those that involved the phosphate groups. This work constitutes the first application of mass spectrometry to the characterization of polyphosphoesters and demonstrates the suitability of high mass accuracy FT-ICR mass spectrometry, with CID and ECD, for the structural analysis of polyphosphoesters and their degradation products

Laser-induced fluorescence studies of the biodistribution of carotenoporphyrins in mice.

The biodistribution of two recently developed tumour markers, trimethylated (CP(Me)3) and trimethoxylated (CP(OMe)3) carotenoporphyrin, was investigated by means of laser-induced fluorescence (LIF) after i.v. injection into 38 tumour-bearing (MS-2 fibrosarcoma) female Balb/c mice. At 3, 24, 48 or 96 h after administration, the carotenoporphyrin fluorescence was measured in tumoral and peritumoral tissue, as well as in the abdominal, thoracic and cranial cavities. The fluorescence was induced by a nitrogen laser-pumped dye laser, emitting light at 425 nm, and analysed by a polychromator equipped with an image-intensified CCD camera. The fluorescence was evaluated at 490, 655 and 720 nm: the second and third wavelengths represent the carotenoporphyrin (CP)-related peaks, whereas the first one is close to the peak of the tissue autofluorescence. The tumour and the liver were the two tissue types showing the strongest carotenoporphyrin-related fluorescence, whereas the cerebral cortex and muscle consistently exhibited weak substance-related fluorescence. In most tissue types, the fluorescence intensities decreased over time. A few exceptions were observed, notably the liver, in which the intensity remained remarkably constant over the time period investigated

Laser-induced fluorescence in malignant and normal tissue in mice injected with two different carotenoporphyrins.

Laser-induced fluorescence (LIF) was used to characterise the localisation of an intravenously administered trimethylated carotenoporphyrin [CP(Me)3] and a trimethoxylated carotenoporphyrin [CP(OMe)3] in an intramuscularly transplanted malignant tumour (MS-2 fibrosarcoma) and healthy muscle in female Balb/c mice, 3, 24, 48 and 96 h post injection. The fluorescence was induced with a dye laser pumped by a nitrogen laser, emitting light at 425 nm. The fluorescence spectra were recorded in the region 455-760 nm using a polychromator equipped with an image-intensified CCD camera. The tumour/peritumoral muscle ratio was about 5:1 for CP(Me)3 and about 6:1 for CP(OMe)3 in terms of the background-free fluorescence intensity, which peaked at about 655 nm. By including the endogenous tissue fluorescence, the contrast was further enhanced by a factor of approximately 2

Unraveling trait relationships in maize inbred lines

An experiment was carried out during Kharif 2020 at wetland farm of Sri Venkateswara Agricultural College, Tirupati using 30 inbred lines of maize to assess the trait association for 16 yield and yield attributes. It revealed that ear length, number of kernels per row, plant height, ear girth, SPAD chlorophyll meter reading, 100 kernel weight, number of kernel rows per ear, specific leaf area, harvest index and tassel length had notable positive correlation with kernel yield per plant suggesting that selecting these characters simultaneously lead to an increase in kernel yield per plant. Path analysis revealed a significant and positive direct influence of ear length on the kernel yield per plant. Hence, ear length could be considered during selection in maize for improving kernel yield