scholarly journals Numerical simulations of colliding jets in an external wind: application to 3C 75

2020 ◽  
Vol 494 (4) ◽  
pp. 5207-5229 ◽  
Author(s):  
G Musoke ◽  
A J Young ◽  
S M Molnar ◽  
M Birkinshaw

ABSTRACT The radio galaxy 3C 75 is remarkable because it contains a pair of radio-loud active galaxies, each of which produces a two-sided jet, with the jet beams appearing to collide and merge to the west of the galaxies. Motivated by 3C 75, we have conducted three-dimensional hydrodynamic simulations of jet collisions. We have extended previous studies by modelling the physical properties of the cluster atmosphere, including an external wind, and using realistic jet powers obtained from observational data. We are able to produce a morphology similar to that of 3C 75. The simulations imply that direct contact between the bulk jet flows on the west of the source is required to produce a morphology consistent with 3C 75. We quantify how the merging jets decelerate, how the wind deflects the jets and cocoons, the entrainment of intra-cluster material into the cocoons, the cocoon energetics, and how the jet interactions generate enstrophy. By comparing simulations of pairs of two-sided jets with those of single two-sided sources, we determine how the interaction between two bipolar jets changes their evolution. The unprecedented sensitivity and angular resolution of upcoming observatories will lead to the detection of many more complex sources at high redshift, where interacting jets are expected to be more numerous. The morphology of these complex sources can provide significant insight into the conditions in their environments.

Author(s):  
Kofi Freeman K. Adane ◽  
Mark F. Tachie

Three-dimensional laminar lid-driven and wall jet flows of various shear-thinning non-Newtonian and Newtonian fluids were numerically investigated. The complete nonlinear incompressible Navier-Stokes equation was solved using a collocated finite-volume based in-house CFD code. From the results, velocity profiles at several locations, jet spread rates, secondary flows and vorticity distributions were used to provide insight into the characteristics of three-dimensional laminar canonical flows of shear-thinning non-Newtonian and Newtonian fluids.


Author(s):  
Martin Agelinchaab ◽  
Mark F. Tachie

This paper reports experimental study of three-dimensional turbulent wall jet over smooth and rough surfaces. The wall jet was created using a square nozzle of size 6 mm and flow into an open channel. The experiments were performed at a Reynolds number based on the nozzle size and jet exit velocity of 4800. A particle image velocimetry was used to conduct detailed measurements over the smooth and rough surfaces at various streamwise-transverse and streamwise-spanwise planes. From these measurements, mean velocities and turbulent quantities were extracted at selected locations. The distributions of the mean velocities, turbulent intensities and Reynolds shear stress were used to provide insight into the characteristics of three-dimensional wall jet flows over smooth and rough surface.


Author(s):  
Peter Sterling

The synaptic connections in cat retina that link photoreceptors to ganglion cells have been analyzed quantitatively. Our approach has been to prepare serial, ultrathin sections and photograph en montage at low magnification (˜2000X) in the electron microscope. Six series, 100-300 sections long, have been prepared over the last decade. They derive from different cats but always from the same region of retina, about one degree from the center of the visual axis. The material has been analyzed by reconstructing adjacent neurons in each array and then identifying systematically the synaptic connections between arrays. Most reconstructions were done manually by tracing the outlines of processes in successive sections onto acetate sheets aligned on a cartoonist's jig. The tracings were then digitized, stacked by computer, and printed with the hidden lines removed. The results have provided rather than the usual one-dimensional account of pathways, a three-dimensional account of circuits. From this has emerged insight into the functional architecture.


2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Lijiao Ma ◽  
Shaoqing Zhang ◽  
Jincheng Zhu ◽  
Jingwen Wang ◽  
Junzhen Ren ◽  
...  

AbstractNon-fullerene acceptors (NFAs) based on non-fused conjugated structures have more potential to realize low-cost organic photovoltaic (OPV) cells. However, their power conversion efficiencies (PCEs) are much lower than those of the fused-ring NFAs. Herein, a new bithiophene-based non-fused core (TT-Pi) featuring good planarity as well as large steric hindrance was designed, based on which a completely non-fused NFA, A4T-16, was developed. The single-crystal result of A4T-16 reveals that a three-dimensional interpenetrating network can be formed due to the compact π–π stacking between the adjacent end-capping groups. A high PCE of 15.2% is achieved based on PBDB-TF:A4T-16, which is the highest value for the cells based on the non-fused NFAs. Notably, the device retains ~84% of its initial PCE after 1300 h under the simulated AM 1.5 G illumination (100 mW cm−2). Overall, this work provides insight into molecule design of the non-fused NFAs from the aspect of molecular geometry control.


2019 ◽  
Vol 10 (2) ◽  
pp. 247-268
Author(s):  
Jane Krishnadas

AbstractThis article engages with a key question raised by feminist legal scholars from the east to the west: whether women should or should not engage in rights strategies? Are rights systematically exercised to reproduce patriarchal, dominant sites of justice, or do rights constitute a multiple and relational force which may transform sites of justice? The experience of women’s engagements with law in South Asia has created a diversity of critical legal knowledge and scholarship reflecting the pluralism of both women’s identities and needs based on caste, religion, class and sexuality across an array of legal spaces from the family, community and state. Women in South Asian scholarship have complicated the notion of the homogenous legal subject and the static dominant site of justice. In this article I return to my underpinning field research whilst living and working within an earthquake affected area of Maharashtra, India in the post-crisis rehabilitation period (1993–1998). This research explored how women exercised their rights to reconstruct lives at different tiers of justice: in public policy, private legislation and the non-formal sphere of community relations to deconstruct the concept of rights existing within a static framework of justice. Drawing upon feminist discourse across the east to the west, I have analysed the role of rights in post-disaster sites to understand how women move from victims to survivors, beneficiaries to contributors and objects to agents of change to inform contemporary research on how women in post-domestic violence situations may exercise rights to reconstruct their lives in times of crisis in the UK. Through this analysis I argue that rights may be empowering if one can exercise one’s right to identity as agency, resources as capacity and location as mobility, as a three dimensional strategy to transform the framework in which one is situated. Over the last decade, I have actively applied this transformative methodology to create an alternative relational, intersectional and holistic legal paradigm, to transform sites of justice, in times of every day crisis, through the CLOCK/ All India Access to Justice Strategy.


Author(s):  
Deep K. Datta-Ray

The history of Indian diplomacy conceptualises diplomacy racially—as invented by the West—and restrictively—to offence. This is ‘analytic-violence’ and it explains the berating of Indians for mimicking diplomacy incorrectly or unthinkingly, and the deleting, dismissing, or denigrating, of diplomatic practices contradicting history’s conception. To relieve history from these offences, a new method is presented, ‘Producer-Centred Research’ (PCR). Initiating with abduction, an insight into a problem—in this case Indian diplomacy’s compromised historicisation—PCR solves it by converting history’s racist rationality into ‘rationalities’. The plurality renders rationality one of many, permitting PCR’s searching for rationalities not as a function of rationality but robust practices explicable in producer’s terms. Doing so is exegesis. It reveals India’s nuclear diplomacy as unique, for being organised by defence, not offence. Moreover, offence’s premise of security as exceeding opponent’s hostility renders it chimerical for such a security is, paradoxically, reliant on expanding arsenals. Additionally, doing so is a response to opponents. This fragments sovereignty and abdicates control for one is dependent on opponent’s choices. Defence, however, does not instigate opponents and so really delivers security by minimising arsenals since offence is eschewed. Doing so is not a response to opponents and so maintains sovereignty and retains control by denying others the right to offense. The cost of defence is courage, for instance, choosing to live in the shadow of nuclear annihilation. Exegesis discloses Balakot as a shift from defence to offence, so to relieve the Bharatiya Janata Party’s (BJP) leadership of having to be courageous. The intensity of the intention to discard courage is apparent in the price the BJP paid. This included equating India with Pakistan, permitting it to escalate the conflict, and so imperiling all humanity in a manner beyond history.


1991 ◽  
Vol 115 (5) ◽  
pp. 1267-1274 ◽  
Author(s):  
S Eliott ◽  
P H Vardy ◽  
K L Williams

While the role of myosin II in muscle contraction has been well characterized, less is known about the role of myosin II in non-muscle cells. Recent molecular genetic experiments on Dictyostelium discoideum show that myosin II is necessary for cytokinesis and multicellular development. Here we use immunofluorescence microscopy with monoclonal and polyclonal antimyosin antibodies to visualize myosin II in cells of the multicellular D. discoideum slug. A subpopulation of peripheral and anterior cells label brightly with antimyosin II antibodies, and many of these cells display a polarized intracellular distribution of myosin II. Other cells in the slug label less brightly and their cytoplasm displays a more homogeneous distribution of myosin II. These results provide insight into cell motility within a three-dimensional tissue and they are discussed in relation to the possible roles of myosin II in multicellular development.


2007 ◽  
Vol 556-557 ◽  
pp. 61-64
Author(s):  
Y. Shishkin ◽  
Rachael L. Myers-Ward ◽  
Stephen E. Saddow ◽  
Alexander Galyukov ◽  
A.N. Vorob'ev ◽  
...  

A fully-comprehensive three-dimensional simulation of a CVD epitaxial growth process has been undertaken and is reported here. Based on a previously developed simulation platform, which connects fluid dynamics and thermal temperature profiling with chemical species kinetics, a complete model of the reaction process in a low pressure hot-wall CVD reactor has been developed. Close agreement between the growth rate observed experimentally and simulated theoretically has been achieved. Such an approach should provide the researcher with sufficient insight into the expected growth rate in the reactor as well as any variations in growth across the hot zone.


2016 ◽  
Vol 60 (4) ◽  
pp. 534-556 ◽  
Author(s):  
Ema Hrešanová

This paper explores the history of the ‘psychoprophylactic method of painless childbirth’ in socialist Czechoslovakia, in particular, in the Czech and Moravian regions of the country, showing that it substantially differs from the course that the method took in other countries. This non-pharmacological method of pain relief originated in the USSR and became well known as the Lamaze method in western English-speaking countries. Use of the method in Czechoslovakia, however, followed a very different path from both the West, where its use was refined mainly outside the biomedical frame, and the USSR, where it ceased to be pursued as a scientific method in the 1950s after Stalin’s death. The method was imported to Czechoslovakia in the early 1950s and it was politically promoted as Soviet science’s gift to women. In the 1960s the method became widespread in practice but research on it diminished and, in the 1970s, its use declined too. However, in the 1980s, in the last decade of the Communist regime, the method resurfaced in the pages of Czechoslovak medical journals and underwent an exciting renaissance, having been reintroduced by a few enthusiastic individuals, most of them women. This article explores the background to the renewed interest in the method while providing insight into the wider social and political context that shaped socialist maternity and birth care in different periods.


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