Vacuum Polarization and Dynamical Chiral Symmetry Breaking: Phase Diagram of QED with Four-Fermion Contact Interaction

We study chiral symmetry breaking for fundamental charged fermions coupled electromagnetically to photons with the inclusion of four-fermion contact self-interaction term. We employ multiplicatively renormalizable models for the photon dressing function and the electron-photon vertex which minimally ensures mass anomalous dimension = 1. Vacuum polarization screens the interaction strength. Consequently, the pattern of dynamical mass generation for fermions is characterized by a critical number of massless fermion flavors above which chiral symmetry is restored. This effect is in diametrical opposition to the existence of criticality for the minimum interaction strength necessary to break chiral symmetry dynamically. The presence of virtual fermions dictates the nature of phase transition. Miransky scaling laws for the electromagnetic interaction strength and the four-fermion coupling, observed for quenched QED, are replaced by a mean-field power law behavior corresponding to a second order phase transition. These results are derived analytically by employing the bifurcation analysis, and are later confirmed numerically by solving the original non-linearized gap equation. A three dimensional critical surface is drawn to clearly depict the interplay of the relative strengths of interactions and number of flavors to separate the two phases. We also compute the beta-function and observe that it has ultraviolet fixed point. The power law part of the momentum dependence, describing the mass function, reproduces the quenched limit trivially. We also comment on the continuum limit and the triviality of QED.Comment: 9 pages, 10 figure

Anti-inflammatory activity and a new compound isolated from aerial parts of Myrsine africana

A new compound was isolated from the ethyl acetate (EtOAc) fraction of the aerial parts of Myrsine africana. The compound was eluted with mobile phase of EtOAc and n-hexane at a ratio of 0.2:9.8. The structure of the compound was identified with the help of 13C-NMR, 1H-NMR, heteronuclear multiple bond correlation (HMBC), heteronuclear multiple quantum coherence (HMQC), nuclear overhauser effect spectroscopy (NOESY) and correlation spectroscopy (COSY). The crude methanolic extract and various fractions of the aerial parts of the plant were also screened for anti-inflammatory activity. The EtOAc and n-hexane fractions of the plant showed moderate (44.8 and 40.9%, respectively) antiinflammatory activity, while the rest of the fractions and crude extract showed low activity at concentration of 500 μg/ml against human neutrophils.Key words: Myrsine africana, anti-inflammatory activity, indomethacin

Mean field exponents and small quark masses

We demonstrate that the restoration of chiral symmetry at finite-T in a class of confining Dyson-Schwinger equation (DSE) models of QCD is a mean field transition, and that an accurate determination of the critical exponents using the chiral and thermal susceptibilities requires very small values of the current-quark mass: log_{10}(m/m_u) < -5. Other classes of DSE models characterised by qualitatively different interactions also exhibit a mean field transition. Incipient in this observation is the suggestion that mean field exponents are a result of the gap equation's fermion substructure and not of the interaction.Comment: 13 pages, 3 figures, REVTEX, epsfi

Robust Multimodal Representation Learning with Evolutionary Adversarial Attention Networks

Multimodal representation learning is beneficial for many multimedia-oriented applications such as social image recognition and visual question answering. The different modalities of the same instance (e.g., a social image and its corresponding description) are usually correlational and complementary. Most existing approaches for multimodal representation learning are not effective to model the deep correlation between different modalities. Moreover, it is difficult for these approaches to deal with the noise within social images. In this paper, we propose a deep learning-based approach named Evolutionary Adversarial Attention Networks (EAAN), which combines the attention mechanism with adversarial networks through evolutionary training, for robust multimodal representation learning. Specifically, a two-branch visual-textual attention model is proposed to correlate visual and textual content for joint representation. Then adversarial networks are employed to impose regularization upon the representation by matching its posterior distribution to the given priors. Finally, the attention model and adversarial networks are integrated into an evolutionary training framework for robust multimodal representation learning. Extensive experiments have been conducted on four real-world datasets, including PASCAL, MIR, CLEF, and NUS-WIDE. Substantial performance improvements on the tasks of image classification and tag recommendation demonstrate the superiority of the proposed approach

Chiral symmetry breaking in dimensionally regularized nonperturbative quenched QED

In this paper we study dynamical chiral symmetry breaking in dimensionally regularized quenched QED within the context of Dyson-Schwinger equations. In D < 4 dimensions the theory has solutions which exhibit chiral symmetry breaking for all values of the coupling. To begin with, we study this phenomenon both numerically and, with some approximations, analytically within the rainbow approximation in the Landau gauge. In particular, we discuss how to extract the critical coupling alpha_c = pi/3 relevant in four dimensions from the D dimensional theory. We further present analytic results for the chirally symmetric solution obtained with the Curtis-Pennington vertex as well as numerical results for solutions exhibiting chiral symmetry breaking. For these we demonstrate that, using dimensional regularization, the extraction of the critical coupling relevant for this vertex is feasible. Initial results for this critical coupling are in agreement with cut-off based work within the currently achievable numerical precision.Comment: 24 pages, including 5 figures; submitted to Phys. Rev.

Prevalence of vitamin D deficiency in Pakistan and implications for the future

Background and aims: Vitamin D deficiency (25-hydroxyvitamin D - VitDD) affects over one billion people worldwide. VitDD results in progression of osteoporosis as well as other conditions. Previous studies have shown high rates of VitDD in Pakistan despite appreciable levels of sunshine. However, none have assessed VitDD across all age groups, genders, incomes and locations to guide future strategies. Methods: Questionnaire and blood sampling among 4830 randomly selected citizens. Results: High levels of VitDD among all age groups, genders, income levels and locations. 53.5% had VitDD, 31.2% had insufficient Vitamin D and only 15.3% normal Vitamin D. Conclusion: High rates of VitDD in Pakistan despite high levels of sunshine and previous Food Acts asking for food fortification with Vitamin D. Public health strategies are needed to address high VitDD rates, including food fortification, i.e. nurture, alongside increasing exposure to sunlight, i.e. nature. This will involve all key stakeholder groups

Factors associated with low birthweight in term pregnancies: A matched case-control study from rural Pakistan

Low birthweight (LBW) remains a significant public health problem in Pakistan and further understanding of factors associated with LBW is required. We conducted a hospital-based matched case control study to identify risk factors associated with LBW in a rural district of Pakistan. We found that illiteracy (AOR: 2.68; 95% CI: 1.59 - 4.38), nulliparity (AOR: 1.82; 95% CI: 1.26-2.44), having a previous miscarriage/abortion (AOR: 1.22; 95% CI: 1.06-2.35), having \u3c 2 antenatal care (ANC) visits during last pregnancy (AOR: 2.43; 95% CI: 1.34-2.88), seeking ANC in third trimester (AOR: 3.62; 95% CI : 2.14-5.03), non-use of iron folic acid during last pregnancy (AOR: 2.72; 95% CI: 1.75-3.17), having hypertension during last pregnancy (AOR: 1.42; 95% CI: 1.13-2.20), being anemic (AOR: 2.67; 95% CI: 1.65-5.24) and having postpartum weight o

Exploring the Impact of Preprocessing Techniques on Retinal Blood Vessel Segmentation Using a Study Group Learning Scheme

The segmentation of retinal vessels in retinal images is vital for automated diagnosis of retinal diseases. This is a challenging task because it requires accurate manual labeling of the vessels by expert clinicians and the detection of tiny vessels is difficult due to limited samples, low contrast, and noise. In this study, we explore the use of preprocessing techniques such as contrast-limited adaptive histogram equalization (CLAHE), grad-cam analysis and min-max contrast stretching to improve the performance of a study-group learning (SGL) segmentation model. We evaluate the impact of these preprocessing techniques on the accuracy, sensitivity, specificity, AUC, IoU, and Dice scores using four publicly available datasets, DRIVE, CHASE, HRF and IOSTAR. Our findings indicate that the utilization of the Min-Max technique resulted in a notable enhancement in the accuracy of both the DRIVE and CHASE datasets, with an approximate increase of 3% and 2% respectively. Conversely, the impact of the CLAHE method was discernible solely in the DRIVE dataset, demonstrating an improvement in accuracy of 1%. In addition, our results demonstrated superior accuracy performance for both the DRIVE and CHASE datasets compared to the findings of the reviewed studies. The GitHub repo for this project is available at Link

P66shc and its downstream Eps8 and Rac1 proteins are upregulated in esophageal cancers

Members of Shc (src homology and collagen homology) family, p46shc, p52shc, p66shc have known to be related to cell proliferation and carcinogenesis. Whereas p46shc and p52shc drive the reaction forward, the role of p66shc in cancers remains to be understood clearly. Hence, their expression in cancers needs to be evaluated carefully so that Shc analysis may provide prognostic information in the development of carcinogenesis. In the present study, the expression of p66shc and its associate targets namely Eps8 (epidermal pathway substrate 8), Rac1 (ras-related C3 botulinum toxin substrate1) and Grb2 (growth factor receptor bound protein 2) were examined in fresh tissue specimens from patients with esophageal squamous cell carcinoma and esophageal adenocarcinoma using western blot analysis. A thorough analysis of both esophageal squamous cell carcinoma and adenocarcinoma showed p66shc expression to be significantly higher in both types of carcinomas as compared to the controls. The controls of adenocarcinoma show a higher basal expression level of p66shc as compared to the controls of squamous cell carcinoma. The expression level of downstream targets of p66shc i.e., eps8 and rac1 was also found to be consistently higher in human esophageal carcinomas, and hence correlated positively with p66shc expression. However the expression of grb2 was found to be equal in both esophageal squamous cell carcinoma and adenocarcinoma. The above results suggest that the pathway operated by p66shc in cancers does not involve the participation of Ras and Grb2 as downstream targets instead it operates the pathway involving Eps8 and Rac1 proteins. From the results it is also suggestive that p66shc may have a role in the regulation of esophageal carcinomas and represents a possible mechanism of signaling for the development of squamous cell carcinoma and adenocarcinoma of esophagus