202 research outputs found
Stability analysis of perturbed plane Couette flow
Plane Couette flow perturbed by a spanwise oriented ribbon, similar to a
configuration investigated experimentally at the Centre d'Etudes de Saclay, is
investigated numerically using a spectral-element code. 2D steady states are
computed for the perturbed configuration; these differ from the unperturbed
flows mainly by a region of counter-circulation surrounding the ribbon. The 2D
steady flow loses stability to 3D eigenmodes at Re = 230, beta = 1.3 for rho =
0.086 and Re = 550, beta = 1.5 for rho = 0.043, where Re is the Reynolds
number, beta is the spanwise wavenumber and rho is the half-height of the
ribbon. For rho = 0.086, the bifurcation is determined to be subcritical by
calculating the cubic term in the normal form equation from the timeseries of a
single nonlinear simulation; steady 3D flows are found for Re as low as 200.
The critical eigenmode and nonlinear 3D states contain streamwise vortices
localized near the ribbon, whose streamwise extent increases with Re. All of
these results agree well with experimental observations
Alien Registration- Franck, Laurette A. (Saint Agatha, Aroostook County)
https://digitalmaine.com/alien_docs/20888/thumbnail.jp
The effects of surface roughness on stagnation-point heat transfer during impingement of turbulent liquid jets
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1993.Includes bibliographical references (leaves 89-92).by Laurette A. Gabour.M.S
Best Practices in the U.S. Lodging Industry: Overview, Methods, and Champions
When a lodging operation is doing an innovative and excellent job in a particular area, the industry benefits from spreading the word about the practice. But first one has to discover those best practices
Managing for Excellence: Conclusions and Challenges from a Study of Best Practices in the U.S Lodging Industry
Perhaps the real challenge of innovation is to continue innovating
Transient growth in Taylor-Couette flow
Transient growth due to non-normality is investigated for the Taylor-Couette
problem with counter-rotating cylinders as a function of aspect ratio eta and
Reynolds number Re. For all Re < 500, transient growth is enhanced by
curvature, i.e. is greater for eta < 1 than for eta = 1, the plane Couette
limit. For fixed Re < 130 it is found that the greatest transient growth is
achieved for eta between the Taylor-Couette linear stability boundary, if it
exists, and one, while for Re > 130 the greatest transient growth is achieved
for eta on the linear stability boundary. Transient growth is shown to be
approximately 20% higher near the linear stability boundary at Re = 310, eta =
0.986 than at Re = 310, eta = 1, near the threshold observed for transition in
plane Couette flow. The energy in the optimal inputs is primarily meridional;
that in the optimal outputs is primarily azimuthal. Pseudospectra are
calculated for two contrasting cases. For large curvature, eta = 0.5, the
pseudospectra adhere more closely to the spectrum than in a narrow gap case,
eta = 0.99
Computational Study of Turbulent-Laminar Patterns in Couette Flow
Turbulent-laminar patterns near transition are simulated in plane Couette
flow using an extension of the minimal flow unit methodology. Computational
domains are of minimal size in two directions but large in the third. The long
direction can be tilted at any prescribed angle to the streamwise direction.
Three types of patterned states are found and studied: periodic, localized, and
intermittent. These correspond closely to observations in large aspect ratio
experiments.Comment: 4 pages, 5 figure
Agents, security and ethics: a framework for analysis
The domain of information security research is no longer exclusively of a technological nature as it has become permeated with aspects of human behaviour. Similarly the broad field of ethics is no longer only a human issue, as is reflected by the establishment of computing ethics as a separate research area. Advances in the past decade have led to the emergence of among others, new technologies, frameworks and methodologies in the field of computing. Examples include the Internet, global connectivity and agent technology - in particular intelligent agents. The attribute intelligentbrings with it a concomitant human characteristic that is assigned to an inanimate technological object. It is even plausible to think of communities of intelligent agents, inhabiting cyberspace, interacting with other agents, human users and hosts, and in this way developing a social life. This raises issues concerning information security as well as the ethical and social behaviour of intelligent agents.
In this paper we thus briefly discuss agent computing and its impact on the environment in which it exists. In particular we focus on some relevant security and ethical issues associated with agent computing. The purpose of the paper is to present a framework within which the security and ethical behaviour of agents can be evaluated and analysed.Institute for Corporate Citizenshi
Folate deficiency increases the incidence of dolutegravir-associated foetal defects in a mouse pregnancy model
Background: Dolutegravir (DTG) is a recommended first-line regimen for all people with Human Immunodeficiency Virus (HIV) infection. Initial findings from Botswana, a country with no folate fortification program, showed an elevated prevalence of neural tube defects (NTDs) with peri-conceptional exposure to DTG. Here we explore whether a low folate diet influences the risk of DTG-associated foetal anomalies in a mouse model. / Methods: C57BL/6 mice fed a folate-deficient diet for 2 weeks, were mated and then randomly allocated to control (water), or 1xDTG (2.5 mg/kg), or 5xDTG (12.5 mg/kg) both administered orally with 50 mg/kg tenofovir disoproxil fumarate 33.3 mg/kg emtricitabine. Treatment was administered once daily from gestational day (GD) 0.5 to sacrifice (GD15.5). Foetuses were assessed for gross anomalies. Maternal and foetal folate levels were quantified. / Findings: 313 litters (103 control, 106 1xDTG, 104 5xDTG) were assessed. Viability, placental weight, and foetal weight did not differ between groups. NTDs were only observed in the DTG groups (litter rate: 0% control; 1.0% 1xDTG; 1.3% 5xDTG). Tail, abdominal wall, limb, craniofacial, and bleeding defects all occurred at higher rates in the DTG groups versus control. Compared with our previous findings on DTG usage in folate-replete mouse pregnancies, folate deficiency was associated with higher rates of several defects, including NTDs, but in the DTG groups only. We observed a severe left-right asymmetry phenotype that was more frequent in DTG groups than controls. / Interpretation: Maternal folate deficiency may increase the risk for DTG-associated foetal defects. Periconceptional folic acid supplementation could be considered for women with HIV taking DTG during pregnancy, particularly in countries lacking folate fortification programs. / Funding: This project has been funded by Federal funds from the Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Department of Health and Human Services, under Contract No. HHSN275201800001I and award #R01HD104553. LS is supported by a Tier 1 Canada Research Chair in Maternal-Child Health and HIV. HM is supported by a Junior Investigator award from the Ontario HIV Treatment Network
Wounds on Rapanea melanophloeos provide habitat for a large diversity of Ophiostomatales including four new species
Rapanea melanophloeos, an important canopy tree in Afromontane forests,
is commonly utilised for medicinal bark harvesting. Wounds created from these
activities provide entrance for many fungi, including arthropod-associated members
of the Ophiostomatales and Microascales (ophiostomatoid fungi). In this study we
assess the diversity of wound-associated Ophiostomatales on storm-damaged R.
melanophloeos trees in the Afromontane forests of South Africa. Five species were identified based on micro-morphological and molecular phylogenetic analyses. These
included Ophiostoma stenoceras and four newly described taxa Sporothrix itsvoense
sp. nov., S. rapaneae sp. nov., S. utae sp. nov. and O. noisomeae sp. nov. Four of
these are members of the S. schenckii-O. stenoceras complex (O. stenoceras, S.
itsvoense sp. nov., S. rapaneae sp. nov., S. utae) while O. noisomeae groups basal in
the Ophiostomatales alongside the S. lignivora complex and Graphilbum. In addition
to other taxa known from this host, the present study shows that there is a rich, yet
still poorly explored, diversity of Ophiostomatales associated with R. melanophloeos
in Afromontane forests. More taxa are likely to be discovered with increased research
effort. These must be assessed in terms of pathogenicity towards this ecologically and
economically important tree.http://link.springer.com/journal/104822017-06-30hb2016GeneticsMicrobiology and Plant Patholog
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