Non-local means based Rician noise filtering for diffusion tensor and kurtosis imaging in human brain and spinal cord

Background: To investigate the effect of using a Rician nonlocal means (NLM) filter on quantification of diffusion tensor (DT)- and diffusion kurtosis (DK)-derived metrics in various anatomical regions of the human brain and the spinal cord, when combined with a constrained linear least squares (CLLS) approach. / Methods: Prospective brain data from 9 healthy subjects and retrospective spinal cord data from 5 healthy subjects from a 3 T MRI scanner were included in the study. Prior to tensor estimation, registered diffusion weighted images were denoised by an optimized blockwise NLM filter with CLLS. Mean kurtosis (MK), radial kurtosis (RK), axial kurtosis (AK), mean diffusivity (MD), radial diffusivity (RD), axial diffusivity (AD) and fractional anisotropy (FA), were determined in anatomical structures of the brain and the spinal cord. DTI and DKI metrics, signal-to-noise ratio (SNR) and Chi-square values were quantified in distinct anatomical regions for all subjects, with and without Rician denoising. / Results: The averaged SNR significantly increased with Rician denoising by a factor of 2 while the averaged Chi-square values significantly decreased up to 61% in the brain and up to 43% in the spinal cord after Rician NLM filtering. In the brain, the mean MK varied from 0.70 (putamen) to 1.27 (internal capsule) while AK and RK varied from 0.58 (corpus callosum) to 0.92 (cingulum) and from 0.70 (putamen) to 1.98 (corpus callosum), respectively. In the spinal cord, FA varied from 0.78 in lateral column to 0.81 in dorsal column while MD varied from 0.91 × 10−3 mm2/s (lateral) to 0.93 × 10−3 mm2/s (dorsal). RD varied from 0.34 × 10−3 mm2/s (dorsal) to 0.38 × 10−3 mm2/s (lateral) and AD varied from 1.96 × 10−3 mm2/s (lateral) to 2.11 × 10−3 mm2/s (dorsal). / Conclusions: Our results show a Rician denoising NLM filter incorporated with CLLS significantly increases SNR and reduces estimation errors of DT- and KT-derived metrics, providing the reliable metrics estimation with adequate SNR levels

A Study on the Effect of Peristalsis and Cilia of MHD Micropolar Fluid Flow through an Inclined Porous Channel

The study of the influence of magnetic field, channel inclination, porous medium and cilia on the Micropolar fluid under different boundary conditions is carried out. The methods of solving Navier Stokes equation specific to Micropolar fluid under the joint influence of these effects are presented. The profiles of velocity (along the flow direction), the micro rotation vector and the variation of pressure rise with time average flow rate for fixed values of other parameters were carried out and the results are discussed

Usability, acceptability, and feasibility of the World Health Organization Labour Care Guide: A mixed-methods, multicountry evaluation.

Introduction The World Health Organization’s (WHO) Labour Care Guide (LCG) is a “next-generation” partograph based on WHO’s latest intrapartum care recommendations. It aims to optimize clinical care provided to women and their experience of care. We evaluated the LCG’s usability, feasibility, and acceptability among maternity care practitioners in clinical settings. Methods Mixed-methods evaluation with doctors, midwives, and nurses in 12 health facilities across Argentina, India, Kenya, Malawi, Nigeria, and Tanzania. Purposively sampled and trained practitioners applied the LCG in low-risk women during labor and rated experiences, satisfaction, and usability. Practitioners were invited to focus group discussions (FGDs) to share experiences and perceptions of the LCG, which were subjected to framework analysis. Results One hundred and thirty-six practitioners applied the LCG in managing labor and birth of 1,226 low-risk women. The majority of women had a spontaneous vaginal birth (91.6%); two cases of intrapartum stillbirths (1.63 per 1000 births) occurred. Practitioner satisfaction with the LCG was high, and median usability score was 67.5%. Practitioners described the LCG as supporting precise and meticulous monitoring during labor, encouraging critical thinking in labor management, and improving the provision of woman-centered care. Conclusions The LCG is feasible and acceptable to use across different clinical settings and can promote woman-centered care, though some design improvements would benefit usability. Implementing the LCG needs to be accompanied by training and supportive supervision, and strategies to promote an enabling environment (including updated policies on supportive care interventions, and ensuring essential equipment is available)

On the development of baroclinic waves influenced by friction and heating

The influence of surface skin friction and a specific type of heating on the stability of baroclinic waves in a two-level, quasi-geostrophic model is investigated. It is found that the effect of friction alone changes the neutral stability curve in such a way that a broader band of wavelengths are unstable for a given value of the vertical windshear. The neutral stability curve is independent of the intensity of friction in this case. The effect of heating is to make all waves longer than a certain critical wave length unstable, but the amplification rate is very small for large values of the wavelength. The combined effect of friction and heating will in general tend to stabilize the waves. The amplification rate is investigated in all cases.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/43246/1/24_2004_Article_BF00874891.pd

BoBBLE: ocean-atmosphere interaction and its impact on the South Asian monsoon

The Bay of Bengal (BoB) plays a fundamental role in controlling the weather systems that make up the South Asian summer monsoon system. In particular,the southern BoB has cooler sea surface temperature (SST) that influence ocean-atmosphere interaction and impact on the monsoon. Compared to the southeast, the southwestern BoB is cooler, more saline, receives much less rain, and is influenced by the Summer Monsoon Current(SMC). To examine the impact of these features on the monsoon, the BoB Boundary Layer Experiment (BoBBLE) was jointly undertaken by India and the UK during June–July 2016. Physical and bio-geochemical observations were made using a CTD, five ocean gliders, a uCTD, a VMP, two ADCPs, Argo floats, drifting buoys, meteorological sensors and upper air radiosonde balloons. The observations were made along a zonal section at 8◦N between 85.3◦E and 89◦E with a 10-day time series at 89◦E, 8◦N. This paper presents the new observed features of the southern BoB from the BoBBLE field program, supported by satellite data. Key results from the BoBBLE field campaign show the Sri Lanka Dome and the SMC in different stages of their seasonal evolution and two freshening events during which salinity decreased in the upper layer leading to the formation of thick barrier layers. BoBBLE observations were taken during a suppressed phase of the intraseasonal oscillation; they captured in detail the warming of the ocean mixed layer and preconditioning of the atmosphere to convection

On the maintenance of the axisymmetric part of the flow in the atmosphere

The maintenance of the axisymmetric component of the flow in the atmosphere is investigated by means of a steady-state, quasi-geostrophic formulation of the meteorological equations. It is shown that the meridional variations in the time-averaged axisymmetric variables can be expressed as the sum of three contributions, one being due to the eddy heat transport, another to the eddy momentum transport, and a third to the convective-radiative equilibrium temperature which enters the problem through the specification of a Newtonian form of diabatic heating. The contributions by the large scale eddies are evaluated through the use of observed values for the eddy heat and momentum transports.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/43251/1/24_2004_Article_BF00878865.pd

On Mean Meridional Circulations in the Atmosphere

The purpose of the study is to make a detailed investigation of mean meridional circulations forced by given eddy transports of heat and momentum and to describe the vertical variation of the energy conversions for the zonally averaged flow. A nonhomogeneous second-order partial differential equation for the vertical p-velocity, a, is obtained from the quasi-geostrophic vorticity and thermodynamic equations. The method of separation of variables is used to solve the zonally averaged form of this equation such that zonally averaged vertical p-velocity, w., is expressed as a series of Legendre polynomials. The boundary conditions used are that W, is zero at the top of the atmosphere and that at the surface it is equal to that value of as which is produced by the topography of the earth. After the solution for wz is obtained, the mean meridional velocity is determined from the zonally averaged continuity equation. The diabatic heating in the meridional plane is estimated from the zonally averaged steady-state thermodynamic equation. Computations of the zonal available potential energy and the conversion from zonal available potential energy to zonal kinetic energy are made using the distributions of diabatic heating, the vertical p-velocity and the temperature in the meridional plane