Predictive haemodynamics in a one-dimensional human carotid artery bifurcation. Part II: application to graft design

A Bayesian surrogate modelling technique is proposed that may be able to predict an optimal bypass graft configuration for patients suffering with stenosis in the internal carotid artery (ICA). At the outset, this statistical technique is considered as a means for identifying key geometric parameters influencing haemodynamics in the human carotid bifurcation. This methodology uses a design of experiments (DoE) technique to generate candidate geometries for flow analysis. A pulsatile one dimensional Navier-Stokes solver incorporating fluid-wall interactions for a Newtonian fluid which predicts pressure and flow in the carotid bifurcation (comprising a stenosed segment in the internal carotid artery) is used for the numerical simulations. Two metrics, pressure variation factor (PVF) and maximum pressure (pm) are employed to directly compare the global and local effects, respectively, of variations in the geometry. The values of PVF and pm are then used to construct two Bayesian surrogate models. These models are statistically analysed to visualise how each geometric parameter influences PVF and pm. Percentage of stenosis is found to influence these pressure based metrics more than any other geometric parameter. Later, we identify bypass grafts with optimal geometric and material properties which have low values of PVF on five test cases with 70%, 75%, 80%, 85% and 90% stenosis in the ICA, respectively

The Latin Leaflet, Number 29

Polymer electrolytes represent the ultimate in terms of desirable properties of energy storage/conversion devices, as they can offer an all-solid-state construction, a wide variety of shapes and sizes, light-weight, low costs, high energy density and safety. Here we present our recent results concerning a novel strategy for preparing efficient polymer membranes which are successfully demonstrated as suitable electrolytes for several energy conversion and storage devices (i.e., Li- and Na-based batteries and DSSCs). Highly ionic conducting polymer electrolytes containing PEO-based functionalities and different components (e.g., Li/Na salts, RTILs, natural biosourced and cellulosic fillers) are successfully prepared via a rapid process and, directly or subsequently, cross-linked via UV irradiation (patent pending, PCT/IT2014/000008). All the prepared materials are thoroughly characterised in terms of their physical, chemical and morphological properties and tested for their electrochemical performances and durability. The UV-curing process on such materials led to the production of elastic and resistant amorphous macromolecular networks. Noticeably increased ionic conductivities are registered (10-3 S cm-1 at RT), along with very stable interfacial and storage stability and wide electrochemical stability windows. The different lab-scale solid-state devices show remarkable performances even at ambient temperature, at the level of those using liquid electrolytes, respect to which demonstrate much greater durability and safety. The obtained findings demonstrate a new, easy and low cost approach to fabricate and tailor-make polymer electrolytes with highly promising prospects for the next generation of advanced flexible energy production and storage devices

Dichotomous venation and anastomosis in the corolla of an orchid-Habenaria dentata (SW.) Schltr

The lip of the corolla in habenaria dentata (Sw.) Schltr. is tripartite. The lateral lobes show dichotomously branched veins. While the majority of the vein-endings are related to crenulation in the corolla and terminate at the tip, others end blindly. Usually each crenulation receives one vein. In exceptional cases two veins enter a crenulation. Cases of veins ending beneath an incision (sinus) separating two crenulations have been observed. Sinus vein dichotomies are present. Nine types of anastomoses are described. In Type I, two branches of a single vein-dichotomy remain united. Type II is characterized by the union of adjacent branches of two vein dichotomies and their separation. Type III is similar to Type II but the branches do not separate after confluence. In Type IV an arcuate vein unites with the branch of contiguous vein dichotomy and then separates. Type V is similar to Type IV but the fused branches do not separate. Type VI is formed by the union of the outer branch of a second order vein-dichotomy and the outer branch of a first order vein-dichotomy. In Type VII one outer branch each of two adjacent second order vein-dichotomies unite and separate. Type VIII is similar to Type VII but the branches do not separate after confluence. In Type IX the outer branch of a third order vein-dichotomy and the outer branch of a second order vein-dichotomy unite and separate after a short area of confluence. Cases of vein-approximations also have been observed

Factors Associated with Tuberculosis and Rifampicin-Resistant Tuberculosis amongst Symptomatic Patients in India: A Retrospective Analysis

Background Tuberculosis remains a major public health challenge for India. Various studies have documented different levels of TB and multi-drug resistant (MDR) TB among diverse groups of the population. In view of renewed targets set under the End TB strategy by 2035, there is an urgent need for TB diagnosis to be strengthened. Drawing on data from a recent, multisite study, we address key questions for TB diagnosis amongst symptomatics presenting for care: are there subgroups of patients that are more likely than others, to be positive for TB? In turn, amongst these positive cases, are there factors—apart from treatment history—that may be predictive for multi-drug resistance? Methods We used data from a multi-centric prospective demonstration study, conducted from March 2012 to December 2013 in 18 sub-district level TB programme units (TUs) in India and covering a population of 8.8 million. In place of standard diagnostic tests, upfront Xpert MTB/RIF testing was offered to all presumptive TB symptomatics. Here, using data from this study, we used logistic regression to identify association between risk factors and TB and Rifampicin-Resistant TB among symptomatics enrolled in the study. Results We find that male gender; history of TB treatment; and adult age compared with either children or the elderly are risk factors associated with high TB detection amongst symptomatics, across the TUs. While treatment history is found be a significant risk factor for rifampicin-resistant TB, elderly (65+ yrs) people have significantly lower risk than other age groups. However, pediatric TB cases have no less risk of rifampicin resistance as compared with adults (OR 1.23 (95% C.I. 0.85–1.76)). Similarly, risk of rifampicin resistance among both the genders was the same. These patterns applied across the study sites involved. Notably in Mumbai, amongst those patients with microbiological confirmation of TB, female patients showed a higher risk of having MDR-TB than male patients. Conclusion Our results cast fresh light on the characteristics of symptomatics presenting for care who are most likely to be microbiologically positive for TB, and for rifampicin resistance. The challenges posed by TB control are complex and multifactorial: evidence from diverse sources, including retrospective studies such as that addressed here, can be invaluable in informing future strategies to accelerate declines in TB burden

Ferromagnetism and the Effect of Free Charge Carriers on Electric Polarization in Y_2NiMnO_6 Double Perovskite

The double perovskite Y_2NiMnO_6 displays ferromagnetic transition at Tc = 81 K. The ferromagnetic order at low temperature is confirmed by the saturation value of magnetization (M_s) and also, validated by the refined ordered magnetic moment values extracted from neutron powder diffraction data at 10 K. This way, the dominant Mn4+ and Ni2+ cationic ordering is confirmed. The cation-ordered P 21/n nuclear structure is revealed by neutron powder diffraction studies at 300 and 10 K. Analysis of frequency dependent dielectric constant and equivalent circuit analysis of impedance data takes into account the bulk contribution to total dielectric constant. This reveals an anomaly which coincides with the ferromagnetic transition temperature (T_c). Pyrocurrent measurements register a current flow with onset near Tc and a peak at 57 K that shifts with temperature ramp rate. The extrinsic nature of the observed pyrocurrent is established by employing a special protocol measurement. It is realized that the origin is due to re-orientation of electric dipoles created by the free charge carriers and not by spontaneous electric polarization at variance with recently reported magnetism-driven ferroelectricity in this materialComment: Published in Physical Review

A multipole-Taylor expansion for the potential of gravitational lens MG J0414+0534

We employ a multipole-Taylor expansion to investigate how tightly the gravitational potential of the quadruple-image lens MG J0414+0534 is constrained by recent VLBI observations. These observations revealed that each of the four images of the background radio source contains four distinct components, thereby providing more numerous and more precise constraints on the lens potential than were previously available. We expand the two-dimensional lens potential using multipoles for the angular coordinate and a modified Taylor series for the radial coordinate. After discussing the physical significance of each term, we compute models of MG J0414+0534 using only VLBI positions as constraints. The best-fit model has both interior and exterior quadrupole moments as well as exterior m=3 and m=4 multipole moments. The deflector centroid in the models matches the optical galaxy position, and the quadrupoles are aligned with the optical isophotes. The radial distribution of mass could not be well constrained. We discuss the implications of these models for the deflector mass distribution and for the predicted time delays between lensed components.Comment: 44 pages, 5 figures, 11 tables, accepted for publication in Ap

Twisted supersymmetric 5D Yang-Mills theory and contact geometry

We extend the localization calculation of the 3D Chern-Simons partition function over Seifert manifolds to an analogous calculation in five dimensions. We construct a twisted version of N=1 supersymmetric Yang-Mills theory defined on a circle bundle over a four dimensional symplectic manifold. The notion of contact geometry plays a crucial role in the construction and we suggest a generalization of the instanton equations to five dimensional contact manifolds. Our main result is a calculation of the full perturbative partition function on a five sphere for the twisted supersymmetric Yang-Mills theory with different Chern-Simons couplings. The final answer is given in terms of a matrix model. Our construction admits generalizations to higher dimensional contact manifolds. This work is inspired by the work of Baulieu-Losev-Nekrasov from the mid 90's, and in a way it is covariantization of their ideas for a contact manifold.Comment: 28 pages; v2: minor mistake corrected; v3: matches published versio

Agrarian distress and livelihood strategies : a study in Pulpalli Panchayat, Wayanad District, Kerala

This paper examines the household livelihood strategies under agrarian distress in Pulpalli Panchayat of Kerala. It also looks at the relationship between household assets and livelihood strategies. The negotiations of institutions by the marginalized and depressed sections of the society were analysed in detail. Major causes of agrarian distress in the study area are the ecological degradation and fall in crops income. Land continues to be the most important asset determining livelihood outcomes. The livelihood strategies have been investigated in relation to land, education, housing pattern, investments & credit facilities, and participation in organizational activities. The livelihood strategies adopted by farmers in the wake of agrarian crisis includes diversification of agriculture, share cropping, organic farming, self-help group activities, cattle rearing, migration and exchange of labour. Livelihood strategies varied across socio-economic groups as farmers owning better landholdings diversified cropping patterns while poor households participated in the activities of SHGs. Casual agricultural labourers and marginal farmers moved to other places in search of jobs. Mitigation of agrarian distress requires public provision of education, health and other social safety measures. Key words: Livelihood risk, Coping Strategies, Livelihood, Livelihood Assets, Institutions, Wayanad, Kerala JEL Classification: Q, Q 0

Non-Commutative Corrections to the MIC-Kepler Hamiltonian

Non-commutative corrections to the MIC-Kepler System (i.e. hydrogen atom in the presence of a magnetic monopole) are computed in Cartesian and parabolic coordinates. Despite the fact that there is no simple analytic expression for non-commutative perturbative corrections to the MIC-Kepler spectrum, there is a term that gives rise to the linear Stark effect which didn't exist in the standard hydrogen model.Comment: 5 page