Numerical Investigation of Heat Transfer Enhancement in a Circular Tube with Rectangular Opened Rings

Turbulent forced convection of coolant air flow (10 m/s velocity) in a steel tube of 50 cm long having outside diameter of 60 mm and inside diameter of 30 mm with constant outside surface temperature of 1000, 1200 and 1400 Ko is numerically analyzed. The renormalization group k-ε model is used to simulate turbulence in ANSYS - FLUENT 14.5. An opened ring of rectangular cross section (5x7 mm) is fitted in the tube and separated by 8cm pitch. Results of temperature and velocity distribution along the tube center line for the case of tube with internal ribs were compared with that of plain tube , these results show that the use of internal ribs enhance the heat transfer rate and found to possess the highest performance factors for turbulent flow

Diverging volumetric trajectories following pediatric traumatic brain injury.

Traumatic brain injury (TBI) is a significant public health concern, and can be especially disruptive in children, derailing on-going neuronal maturation in periods critical for cognitive development. There is considerable heterogeneity in post-injury outcomes, only partially explained by injury severity. Understanding the time course of recovery, and what factors may delay or promote recovery, will aid clinicians in decision-making and provide avenues for future mechanism-based therapeutics. We examined regional changes in brain volume in a pediatric/adolescent moderate-severe TBI (msTBI) cohort, assessed at two time points. Children were first assessed 2-5 months post-injury, and again 12 months later. We used tensor-based morphometry (TBM) to localize longitudinal volume expansion and reduction. We studied 21 msTBI patients (5 F, 8-18 years old) and 26 well-matched healthy control children, also assessed twice over the same interval. In a prior paper, we identified a subgroup of msTBI patients, based on interhemispheric transfer time (IHTT), with significant structural disruption of the white matter (WM) at 2-5 months post injury. We investigated how this subgroup (TBI-slow, N = 11) differed in longitudinal regional volume changes from msTBI patients (TBI-normal, N = 10) with normal WM structure and function. The TBI-slow group had longitudinal decreases in brain volume in several WM clusters, including the corpus callosum and hypothalamus, while the TBI-normal group showed increased volume in WM areas. Our results show prolonged atrophy of the WM over the first 18 months post-injury in the TBI-slow group. The TBI-normal group shows a different pattern that could indicate a return to a healthy trajectory

Prevalence of hepatitis B in the blood donors of NW. F.P and FATA regions and the current scenario of HBV infection in Pakistan

Hepatitis B is a fatal liver disease caused by the hepatitis B virus. In this study, blood donors from various districts of the North-western frontier province and the federally administered tribal area (FATA) of Pakistan were tested for HBsAg and HBV DNA by ICT (Immuno-chromatographic test), ELISA and RTPCR. Out of the 7148 blood donors, 244 (3.41%) were positive for HBsAg by ICT, 147 (2.05%) by ELISA while 132 (1.85%) were positive by PCR. Our data indicates that the incidence of hepatitis B has decreased in these regions in recent times.Key words: HBV, HBsAg, Pakistan

“Turning Point”: Evaluating the Impact of a Three-Month UK-Based Clinical Education Training Programme for Physicians from a Chinese Medical School

Purpose: Transnational faculty development programmes are increasingly popular in medicine, although evaluation of such activities rarely considers longer-term outcomes or the impact of language training. This study attempts to fill this gap by evaluating the lasting impacts of a three-month clinical education and English language training programme at University College London Medical School, UK, for medical educators from Ningbo University, China. Methods: In-depth, semi-structured interviews were conducted in China with 41 participants who had completed the programme between 2013 and 2018. Interview data were analysed using an inductive thematic analysis, and themes were categorised using the four primary components of the faculty development model outlined by Irby and O’Sullivan (2011) – context, facilitator, programme, and participant. Results: Contextual impacts included the importance of participants learning in the familiar environment of their own clinical discipline, the cultural enrichment gained by spending time overseas, reflecting on differences in health-care systems, and attempts to implement and disseminate learning on return to China. Facilitator-related factors included new insights into the student–educator relationship and valuing the support of programme mentors. Programme-related factors included exposure to new teaching methods and technical presentation skills, the challenges of navigating observership placements, spoken English language and pronunciation issues, and establishing a peer network of medical educators. Participant-related factors included improved confidence and self-reflection, adjusting educational approaches for different student groups, and career development in medical education. Conclusion: Participants gained teaching confidence from their engagement in the programme and many described it as a turning point in their careers as educators. Although in the period after attending, individuals changed their own practices and influenced colleagues within their organisation, often through taking on senior roles, and systematic education changes were generally not implemented. Dedicated English language classes and clinical placements were considered the most positive features of the programme

Joint Optimal Power Control and Beamforming in Wireless Networks Using Antenna Arrays

The interference reduction capability of antenna arrays and the power control algorithms have been considered separately as means to increase the capacity in wireless communication networks. The MVDR (Minimum Variance Distortionless Responses) beamformer maximizes the Carrier to Interference Ratio (CIR) when it is employed in the receiver of a wireless link. In a system with omnidirectional antennas, power control algorithms are used to maximize CIR as well. In this paper we consider a system with beamforming capabilities in the receiver, and power control. an iterative algorithm is proposed to jointly update the transmission powers and the beamformer weights so that the coverage to the jointly optimal beamforming and transmission power vector. The algorithm is distributed and uses only local interference measurements. In an uplink transmission scenario it is shown how base assignment can be incorporated in addition to beamforming and power control such that a globally optimum solution is obtained. the network capacity increase and the saving in mobile power achieved by beamforming are evaluated through numerical study

Evolutionary bi-stability in pathogen transmission mode

Many pathogens transmit to new hosts by both infection (horizontal transmission) and transfer to the infected host's offspring (vertical transmission). These two transmission modes require speci®c adap- tations of the pathogen that can be mutually exclusive, resulting in a trade-off between horizontal and vertical transmission. We show that in mathematical models such trade-offs can lead to the simultaneous existence of two evolutionary stable states (evolutionary bi-stability) of allocation of resources to the two modes of transmission. We also show that jumping between evolutionary stable states can be induced by gradual environmental changes. Using quantitative PCR-based estimates of abundance in seed and vege- tative parts, we show that the pathogen of wheat, Phaeosphaeria nodorum, has jumped between two distinct states of transmission mode twice in the past 160 years, which, based on published evidence, we interpret as adaptation to environmental change. The ®nding of evolutionary bi-stability has impli- cations for human, animal and other plant diseases. An ill-judged change in a disease control programme could cause the pathogen to evolve a new, and possibly more damaging, combination of transmission modes. Similarly, environmental changes can shift the balance between transmission modes, with adverse effects on human, animal and plant health

The bends on a quantum waveguide and cross-products of Bessel functions

A detailed analysis of the wave-mode structure in a bend and its incorporation into a stable algorithm for calculation of the scattering matrix of the bend is presented. The calculations are based on the modal approach. The stability and precision of the algorithm is numerically and analytically analysed. The algorithm enables precise numerical calculations of scattering across the bend. The reflection is a purely quantum phenomenon and is discussed in more detail over a larger energy interval. The behaviour of the reflection is explained partially by a one-dimensional scattering model and heuristic calculations of the scattering matrix for narrow bends. In the same spirit we explain the numerical results for the Wigner-Smith delay time in the bend.Comment: 34 pages, 21 figure

Evolution of Surface Acoustic Waves in an Optical Microfiber

This paper reports stimulated Brillouin scattering characterization in a tapered optical fiber using full-vectorial finite element-based numerical methods. Numerical simulations of both optical and acoustic waves’ propagation through a tapered microfiber have been carried out. Acoustic modes over a range of wavenumber for different fiber core radii are obtained and nature of their both dominant and non-dominant displacement vector profiles are studied and discussed. Acoustic mode profiles show confinement of the acoustic wave predominantly at the core cladding interface. In addition, the acoustooptical overlap factors at different fiber radii are also presented