Baryon Destruction by Asymmetric Dark Matter

We investigate new and unusual signals that arise in theories where dark matter is asymmetric and carries a net antibaryon number, as may occur when the dark matter abundance is linked to the baryon abundance. Antibaryonic dark matter can cause {\it induced nucleon decay} by annihilating visible baryons through inelastic scattering. These processes lead to an effective nucleon lifetime of 10^{29}-10^{32} years in terrestrial nucleon decay experiments, if baryon number transfer between visible and dark sectors arises through new physics at the weak scale. The possibility of induced nucleon decay motivates a novel approach for direct detection of cosmic dark matter in nucleon decay experiments. Monojet searches (and related signatures) at hadron colliders also provide a complementary probe of weak-scale dark-matter--induced baryon number violation. Finally, we discuss the effects of baryon-destroying dark matter on stellar systems and show that it can be consistent with existing observations.Comment: 26 pages, 6 figure

Early Recognition of Burn- and Trauma-Related Acute Kidney Injury: A Pilot Comparison of Machine Learning Techniques.

Severely burned and non-burned trauma patients are at risk for acute kidney injury (AKI). The study objective was to assess the theoretical performance of artificial intelligence (AI)/machine learning (ML) algorithms to augment AKI recognition using the novel biomarker, neutrophil gelatinase associated lipocalin (NGAL), combined with contemporary biomarkers such as N-terminal pro B-type natriuretic peptide (NT-proBNP), urine output (UOP), and plasma creatinine. Machine learning approaches including logistic regression (LR), k-nearest neighbor (k-NN), support vector machine (SVM), random forest (RF), and deep neural networks (DNN) were used in this study. The AI/ML algorithm helped predict AKI 61.8 (32.5) hours faster than the Kidney Disease and Improving Global Disease Outcomes (KDIGO) criteria for burn and non-burned trauma patients. NGAL was analytically superior to traditional AKI biomarkers such as creatinine and UOP. With ML, the AKI predictive capability of NGAL was further enhanced when combined with NT-proBNP or creatinine. The use of AI/ML could be employed with NGAL to accelerate detection of AKI in at-risk burn and non-burned trauma patients

Heatline visualization of natural convection in a porous cavity occupied by a fluid with temperature-dependent viscosity

Temperature dependent viscosity effect in buoyancy driven flow, of a gas or a liquid, in an enclosure filled with a porous medium is studied numerically, based on the general model of momentum transfer in a porous medium. The Arrhenius model, which proposes an exponential form of viscosity-temperature relation, is applied to examine three cases of viscosity-temperature relation: constant, decreasing and increasing. Application of arithmetic and harmonic mean values of the viscosity is also investigated for their ability to represent the Nusselt number versus the effective Rayleigh number. Heatlines are illustrated for a more comprehensive investigation of the problem

Complete improvement in a patient with multiple irreversible defects of the left ventricle on 99m technetium-sestamibi SPECT after percutaneous coronary intervention.

99mTc-sestamibi has been investigated as a potential viability marker; initial studies have shown good concordance between 201Tl and 99mTc-sestamibi activities in both viable and nonviable myocardium. However, assessment of myocardial viability by 99mTc-sestamibi remains controversial for tissue recovery after revascularization. Here, we present a patient with several regions of severely diminished and irreversible (defect persisting in both early and delay images of each set scanning) defects on initial scan which were dissolved completely on the follow up scan after an intervention. In a 75 year-old Asian woman with acute myocardial infarction who received thrombolytic therapy and subjected to percutaneous coronary angiography (PCI) on day 28 after acute myocardial infarction(MI), resting 99mTc-sestamibi SPECT was applied on day 4 (initial scan) and 138 (follow up scan) after acute MI at 30 and 180 min after injection of tracer (740 MBq); Two-dimensional echocardiography was carried out at the same time. On the initial image set, there was irreversible defects in the apex, anteroapical, inferoapical, anteroseptal, septal and also anterior walls, while the follow up image was normal in all regions.The angiography intervention showed just significant stenosis on left anterior descending (LAD) vessel (95). This may highlight the failure of 99mTc-sestamibi as a marker of myocardial viability and also mandate further validating of the procedure with follow up scan or other modalities for myocardial viability investigation

Effects of temperature-dependent viscosity variation on entropy generation, heat and fluid flow through a porous-saturated duct of rectangular cross-section

Effect of temperature-dependent viscosity on fully developed forced convection in a duct of rectangular cross-section occupied by a fluid-saturated porous medium is investigated analytically. The Darcy flow model is applied and the viscosity-temperature relation is assumed to be an inverse-linear one. The case of uniform heat flux on the walls, i.e. the H boundary condition in the terminology of Kays and Crawford, is treated. For the case of a fluid whose viscosity decreases with temperature, it is found that the effect of the variation is to increase the Nusselt number for heated walls. Having found the velocity and the temperature distribution, the second law of thermodynamics is invoked to find the local and average entropy generation rate. Expressions for the entropy generation rate, the Bejan number, the heat transfer irreversibility, and the fluid flow irreversibility are presented in terms of the Brinkman number, the Péclet number, the viscosity variation number, the dimensionless wall heat flux, and the aspect ratio (width to height ratio). These expressions let a parametric study of the problem based on which it is observed that the entropy generated due to flow in a duct of square cross-section is more than those of rectangular counterparts while increasing the aspect ratio decreases the entropy generation rate similar to what previously reported for the clear flow case

The diagnostic value of 99mTc-IgG scintigraphy in the diabetic foot and comparison with 99mTc-MDP scintigraphy

Diabetic foot infection is the most common etiology of nontraumatic amputation of the lower extremities, and early diagnosis is of great importance in its management. The aim of this prospective study was to evaluate the strength of 99mTc-IgG scintigraphy in diagnosis of osteomyelitis of the diabetic foot and to compare 99mTc-IgG scintigraphy with 99mTc-methylene diphosphonate (MDP) scintigraphy. Methods: A prospective university hospital-based study was performed over 24 mo. Eighteen patients with type II diabetes and foot ulcers (15 men and 3 women; age range, 45-80 y) were referred for imaging because of clinically suspected osteomyelitis. Early (5-h) and late (24-h) 99mTc-IgG scanning and 3-phase skeletal scintigraphy were completed for all patients at a 3- to 4-d interval. Regions of interest over the involved bony sites and the contralateral normal sites were drawn, and the abnormal-to-normal ratios were acquired for both 99mTc-IgG and 99mTc-MDP studies. Results: From a total of 23 lesions, we observed 10 sites of osteomyelitis, 10 sites of cellulitis, and 3 sites of aseptic inflammation confirmed by MRI, clinical presentation, histopathologic examination, and follow-up evaluation as a gold standard. Both 99mTc-IgG and 99mTc-MDP scanning showed excellent sensitivity for diagnosis of osteomyelitis, but the specificity was significantly lower (69.2% and 53.8%, respectively). Sensitivity, specificity, and accuracy in the diagnosis of osteomyelitis were, respectively, 100%, 53.8%, 73.9% for 99mTc-MDP scanning; 100%, 69.2%, 82.6% for 5-h 99mTc-IgG scanning; and 60%, 76.9%, 69.5% for 24-h 99mTc-IgG scanning. There was no significant difference between the semiquantitative indices of 5-h and 24-h 99mTc-IgG scanning for inflammation, cellulitis, and osteomyelitis. Conclusion: Although both 99mTc-IgG and 99mTc-MDP scintigraphy have high sensitivity for the diagnosis of osteomyelitis, the specificity of these studies is poor. For 99mTc-IgG scintigraphy, 5-h images appear to be adequate, and there is little benefit to performing additional imaging at 24 h. © 2011 by the Society of Nuclear Medicine, Inc

Gravitational Baryogenesis

We show that a gravitational interaction between the derivative of the Ricci scalar curvature and the baryon-number current dynamically breaks CPT in an expanding universe and, combined with baryon-number-violating interactions, can drive the universe towards an equilibrium baryon asymmetry that is observationally acceptable.Comment: Revtex4, 4 pages, two figure

Effects of viscous dissipation and boundary conditions on forced convection in a channel occupied by a saturated porous medium

Forced convection with viscous dissipation in a parallel plate channel filled by a saturated porous medium is investigated numerically. Three different viscous dissipation models are examined. Two different sets of wall conditions are considered: isothermal and isoflux. Analytical expressions are also presented for the asymptotic temperature profile and the asymptotic Nusselt number. With isothermal walls, the Brinkman number significantly influences the developing Nusselt number but not the asymptotic one. At constant wall heat flux, both the developing and the asymptotic Nusselt numbers are affected by the value of the Brinkman number. The Nusselt number is sensitive to the porous medium shape factor under all conditions considered

Effects of viscous dissipation and boundary conditions on forced convection in a channel occupied by a saturated porous medium

Forced convection with viscous dissipation in a parallel plate channel filled by a saturated porous medium is investigated numerically. Three different viscous dissipation models are examined. Two different sets of wall conditions are considered: isothermal and isoflux. Analytical expressions are also presented for the asymptotic temperature profile and the asymptotic Nusselt number. With isothermal walls, the Brinkman number significantly influences the developing Nusselt number but not the asymptotic one. At constant wall heat flux, both the developing and the asymptotic Nusselt numbers are affected by the value of the Brinkman number. The Nusselt number is sensitive to the porous medium shape factor under all conditions considered