Leading the Charge by Dr. Rahul Ravilla: The Newer Immune-Related Side-Effects Impacts Continuity of Care in Individuals with Cancer on Immune Checkpoint Inhibitors

Immunotherapy agents for treatment of cancer have been explored for several decades, but effective drugs have only recently been identified and are increasingly being used in multiple cancer types. In parallel, there is growing recognition of adverse side effects in multiple organ systems mediated by dysregulation of the immune system, which can be exacerbated by co-morbidities often found in cancer patients such as diabetes, chronic lung diseases, and hypertension. These often results after several months of initiation of the immunotherapy. As a result, internists and other non-oncology clinicians are routinely encountering immunotherapy patients in the continuity clinics, who present with a varied range of symptoms. These information and enhancement of health literacy is being facilitated with novel contributions of Dr. Rahul Ravilla, a consultant hemato-oncologist with deep passion in high-value chronic care of cancer patients

Influence of the Darrieus-Landau instability on the propagation of planar turbulent flames

The propagation of premixed flames in weak two-dimensional homogeneous turbulent flows is studied numerically via a hybrid Navier-Stokes/front capturing methodology within the context of a hydrodynamic model, which treats the flame as a surface of density discontinuity separating the burnt and unburnt gases. The focus is the influence of the Darrieus-Landau instability on the turbulent flame, which has been recognized recently to have a dramatic effect on its structure and the turbulent flame speed. Such instability, controlled by a parameter inversely proportional to the Markstein length, can be triggered in a laboratory setting by variations in system pressure or in fuel type and composition. Particular attention in this study is devoted to the influence of the Darrieus-Landau instability on a turbulent, statistically planar flame. Results are therefore limited to positive Markstein length corresponding to lean hydrocarbon-air or rich hydrogen-air mixtures. We show that, although the planar flame under similar but laminar conditions is stable, it is nonetheless affected by the instability in the presence of a turbulent incident flowfield. The turbulent flame speed is observed to exhibit, in addition to the effect of thermal expansion, a nontrivial dependence on the instability parameter and on the turbulence integral scale both effects modulating, in the weak turbulence regime, the well established quadratic dependence of turbulent flame speed on turbulence intensity. (C) 2012 The Combustion Institute. Published by Elsevier Inc. All rights reserved

The turbulent flame speed for low-to-moderate turbulence intensities: Hydrodynamic theory vs. experiments

This paper, dedicated to Norbert Peters, follows his lead in developing theoretical understanding of the complex flow-turbulence interactions occurring in the propagation of premixed flames. The work is based on the asymptotic hydrodynamic model of premixed flames, where the flame is modeled by a surface that separates unburned and burned gases and propagates relative to the incoming flow at a speed that depends locally on the flame stretch rate. As such the work may be categorized as corresponding to the “flamelet regime”, based on the turbulent combustion regimes diagram. The results at the present are limited to mixtures corresponding to positive Markstein lengths, and to “two-dimensional turbulent flows”. In this parametric study, the different factors affecting the turbulent flame speed have been examined and scaling laws for the turbulent flame speed are proposed for low-to-moderate turbulence intensities that highlight the dependence on physically measurable quantities. Comparison to various empirical correlations suggested in the literature is presented. The results, devoid of turbulence-modeling assumptions and/or ad-hoc coefficients, can help explaining the influence of varying the system parameters individually and collectively, and formulating physically-based small-scale models for large-scale numerical simulations of turbulent flames

Turbulent propagation of premixed flames in the presence of Darrieus-Landau instability.

We investigate the role played by hydrodynamic instability in the wrinkled flamelet regime of turbulent combustion, where the intensity of turbulence is small compared to the laminar flame speed and the scale large compared to the flame thickness. To this end the Michelson-Sivashinsky (MS) equation for flame front propagation in one and two spatial dimensions is studied in the presence of uncorrelated and correlated noise representing a turbulent flow field. The combined effect of turbulence intensity, integral scale, and an instability parameter related to the Markstein length are examined and turbulent propagation speed monitored for both stable planar flames and corrugated flames for which the planar conformation is unstable. For planar flames a particularly simple scaling law emerges, involving quadratic dependence on intensity and a linear dependence on the degree of instability. For corrugated flames we find the dependence on intensity to be substantially weaker than quadratic, revealing that corrugated flames are more resilient to turbulence than planar flames. The existence of a threshold turbulence intensity is also observed, below which the corrugated flame in the presence of turbulence behaves like a laminar flame. We also analyze the conformation of the flame surface in the presence of turbulence, revealing primary, large-scale wrinkles of a size comparable to the main corrugation. When the integral scale is much smaller than the characteristic corrugation length we observe, in addition to primary wrinkles, secondary small-scale wrinkles contaminating the surface. The flame then acquires a multi-scale, self-similar conformation, with a fractal dimension, for one-dimensional flames, plateauing at 1.23 for large intensities. The existence of an intermediate integral scale is also found at which the turbulent speed is maximized. When two-dimensional flames are subject to turbulence, the primary wrinkling patterns give rise to polyhedralcellular structures which bear a very close resemblance to those observed in experiments on hydrodynamically unstable expanding spherical flames

Propagation of premixed flames in the presence of Darrieus–Landau and thermal diffusive instabilities

We study the propagation of premixed flames, in the absence of external turbulence, under the effect of both hydrodynamic (Darrieus–Landau) and thermodiffusive instabilities. The Sivashinsky equation in a suitable parameter space is initially utilized to parametrically investigate the flame propagation speed under the potential action of both kinds of instability. An adequate variable transformation shows that the propagation speed can collapse on a universal scaling law as a function of a parameter related to the number of unstable wavelengths within the domain nc. To assess whether this picture can persist in realistic flames, a DNS database of large scale, two-dimensional flames is presented, embracing a range of nc values and subject to either purely hydrodynamic instability (DL) or both kinds of instability (TD). With the aid of similar DNS databases from the literature we observe that when adequately rescaled, propagation speeds follow two distinct scaling laws, depending on the presence of thermodiffusive instability or lack thereof. We verify the presence of secondary cutoff values for nc identifying (a) the insurgence of secondary wrinkling in purely hydrodynamically unstable flames and (b) the attainment of domain independence in thermodiffusively unstable flames. A possible flame surface density based model for the subgrid wrinkling is also proposed

Cataract Surgery Complications in Uveitis Patients: A Review Article

Uveitis is a leading causes of blindness worldwide, and the development of cataracts is common due to both the presence of intraocular inflammation and the most commonly employed treatment with corticosteroids. The management of these cataracts can be very challenging and often requires additional procedures that can compromise surgical results. The underlying disease affects a relatively young population at higher risk of complications. Preoperative control of inflammation/quiescent disease for at least three months is generally accepted as the minimum amount of time prior to surgical intervention. Phacoemulsification with intraocular lens is the preferred method for surgery, with some studies showing improvement in visual acuity in over 90% of patients. The most common postoperative complications include macular edema, posterior capsule opacification, recurrent or persistent inflammation, glaucoma, epiretinal membrane and IOL deposits, or dislocation. Despite the potential complications, cataract surgery in uveitis patients is considered a safe and successful procedure

Current approaches to diagnosis and management of ocular lesions in human immunodeficiency virus positive patients

Human immunovirus infection in India is rapidly increasing. Ocular lesions due to highly active antiretroviral therapy have been well recognized. Acquired immunodeficiency syndrome can affect all parts of the eye. However, posterior segment lesions are the most common and of these, Human immunodeficiency virus retinopathy and cytomegalovirus retinitis predominate. Often clinical examination can establish the diagnosis of many ocular lesions in acquired immunodeficiency syndrome; therefore, ophthalmologists need to be aware of the more common ones. Various drugs in different routes can used to treat cytomegalovirus retinitis. Highly active antiretroviral therapy has remarkably reduced systemic and ocular morbidity among acquired immunodeficiency syndrome patients. To facilitate care of these patients aseptic precautions for ophthalmic care personnel are now well established and therefore ophthalmologist should not hesitate to provide ophthalmic care to acquired immunodeficiency syndrome patients