scholarly journals Asymptotics of streamwise Reynolds stress in wall turbulence

2021 ◽  
Vol 931 ◽  
Author(s):  
Peter A. Monkewitz
Keyword(s):  
Laboratory Data ◽  
Outer Part ◽  
Peak Stress ◽  
Wall Turbulence ◽  
Negative Slope ◽  
Outer Expansion ◽  
Logarithmic Decay ◽  
Turbulent Wall ◽  
First Time ◽  
O 10

The scaling of different features of streamwise normal stress profiles $\langle uu\rangle ^+(y^+)$ in turbulent wall-bounded flows is the subject of a long-running debate. Particular points of contention are the scaling of the ‘inner’ and ‘outer’ peaks of $\langle uu\rangle ^+$ at $y^+\approxeq ~15$ and $y^+ ={O}(10^3)$ , respectively, their infinite Reynolds number limit, and the rate of logarithmic decay in the outer part of the flow. Inspired by the thought-provoking paper of Chen & Sreenivasan (J. Fluid Mech., vol. 908, 2021, p. R3), two terms of an inner asymptotic expansion of $\langle uu\rangle ^+$ in the small parameter $Re_{\tau }^{-1/4}$ are constructed from a set of direct numerical simulations (DNS) of channel flow. This inner expansion is for the first time matched through an overlap layer to an outer expansion, which not only fits the same set of channel DNS within 1.5 % of the peak stress, but also provides a good match of laboratory data in pipes and the near-wall part of boundary layers, up to the highest $Re_{\tau }$ values of $10^5$ . The salient features of the new composite expansion are first, an inner $\langle uu\rangle ^+$ peak, which saturates at 11.3 and decreases as $Re_{\tau }^{-1/4}$ . This inner peak is followed by a short ‘wall log law’ with a slope that becomes positive for $Re_{\tau }$ beyond ${O}(10^4)$ , leading up to an outer peak, followed by the logarithmic overlap layer with a negative slope going continuously to zero for $Re_{\tau }\to \infty$ .

On the size of the energy-containing eddies in the outer turbulent wall layer

2012 ◽  
Vol 702 ◽  
pp. 521-532 ◽  
Author(s):  
Sergio Pirozzoli
Keyword(s):  
Outer Part ◽  
Eddy Diffusivity ◽  
Wall Layer ◽  
Wall Turbulence ◽  
Normal Velocity ◽  
Mixing Length ◽  
Mean Velocity ◽  
Local Mean ◽  
Turbulent Wall ◽  
Good Agreement

AbstractWe investigate the scaling of the energy-containing eddies in the outer part of turbulent wall layers. Their spanwise integral length scales are extracted from a direct numerical simulation (DNS) database, which includes compressible turbulent boundary layers and incompressible turbulent Couette–Poiseuille flows. The results indicate similar behaviour for all classes of flows, with a general increasing trend in the eddy size with the wall distance. A family of scaling relationships are proposed based on simple dimensional arguments, of which the classical mixing length approximation constitutes one example. As in previous studies, we find that the mixing length is in good agreement with the size distribution of the eddies carrying wall-normal velocity, which are active in establishing the mean velocity distribution. However, we find that the eddies associated with wall-parallel motions obey a different scaling, which is controlled by the local mean shear and by an effective eddy diffusivity ${\nu }_{t} = { u}_{\tau }^{\ensuremath{\ast} } \delta $, where ${ u}_{\tau }^{\ensuremath{\ast} } $ is the compressible counterpart of the friction velocity, and $\delta $ is the thickness of the wall layer. The validity of the proposed scalings is checked against DNS data, and the potential implications for the understanding of wall turbulence are discussed.

scholarly journals Difficulties in primary diagnosis of HIV infection at the stages of health care settings

2020 ◽  
Vol 25 (1) ◽  
pp. 11-17
Author(s):  
Elena V. Esaulenko ◽  
Kseniya E. Novak ◽  
Thierry Ingabire ◽  
Sof’ya A. Semenova ◽  
Aleksandra O. Nikiforova
Keyword(s):  
Infectious Diseases ◽  
Hiv Infection ◽  
Primary Care Physicians ◽  
Sexual Transmission ◽  
Laboratory Data ◽  
Primary Diagnosis ◽  
Newly Diagnosed ◽  
Hiv Diagnosis ◽  
Rapid Tests ◽  
First Time

Aim: to demonstrate the difficulties and timeliness of HIV diagnosis by primary care physicians, to carry out a clinical and epidemiological analysis of newly diagnosed cases of HIV infection. Materials and methods: The study evaluated the routing of diagnosis and analyzed the epidemiological and clinical and laboratory data of 85 patients with a newly diagnosed HIV infection hospitalized in the St. Petersburg Clinical Infectious Diseases Hospital named after S. P. Botkin during the period from November 2018 to October 2019. To confirm positive results, ELISA and western blot were used. Results: Among the observed patients, 71.3% were women and 28.7% were men. The average age was 39.3 2 years. Upon admission to the infectious diseases hospital with an established diagnosis of HIV infection, 49.5% were hospitalized in specialized departments (n = 42). Of them, nine (9) were referred by the polyclinic with an established diagnosis, in 20 patients the diagnosis was established in somatic hospitals, and emergency room doctors newly diagnosed HIV infection in 13 more patients. The remaining 50.5% (n = 43) were hospitalized in various departments with other diagnoses. Clinical and laboratory analysis of these patients showed that for the first time in life, an established diagnosis of HIV infection corresponded to both early (15.3%) and late (84.7%) stages of the disease with dominance of sexual transmission of the virus (43.6%). Conclusion: HIV infection at both early and late stages can manifest under the guise of various other diseases, which makes it necessary to expand testing of patients for HIV infection, including using rapid tests.

scholarly journals αIIbβ3 variants in ten families with autosomal dominant macrothrombocytopenia: Expanding the mutational and clinical spectrum

PLoS ONE ◽  
2020 ◽  
Vol 15 (12) ◽  
pp. e0235136
Author(s):  
Sara Morais ◽  
Jorge Oliveira ◽  
Catarina Lau ◽  
Mónica Pereira ◽  
Marta Gonçalves ◽  
...  
Keyword(s):  
Binding Sites ◽  
Autosomal Dominant ◽  
Transmembrane Domain ◽  
Laboratory Data ◽  
Atp Release ◽  
Cytoplasmic Domains ◽  
Pathogenic Variants ◽  
Distinct Disease ◽  
And Function ◽  
First Time

Background Rare pathogenic variants in either the ITGA2B or ITGB3 genes have been linked to autosomal dominant macrothrombocytopenia associated with abnormal platelet production and function, deserving the designation of Glanzmann Thrombasthenia-Like Syndrome (GTLS) or ITGA2B/ITGB3-related thrombocytopenia. Objectives To describe a series of patients with familial macrothrombocytopenia and decreased expression of αIIbβ3 integrin due to defects in the ITGA2B or ITGB3 genes. Methods We reviewed the clinical and laboratory records of 10 Portuguese families with GTLS (33 patients and 11 unaffected relatives), including the functional and genetic defects. Results Patients had absent to moderate bleeding, macrothrombocytopenia, low αIIbβ3 expression, impaired platelet aggregation/ATP release to physiological agonists and low expression of activation-induced binding sites on αIIbβ3 (PAC-1) and receptor-induced binding sites on its ligand (bound fibrinogen), upon stimulation with TRAP-6 and ADP. Evidence for constitutive αIIbβ3 activation, occurred in 2 out of 9 patients from 8 families studied, but also in 2 out of 12 healthy controls. We identified 7 missense variants: 3 in ITGA2B (5 families), and 4 in ITGB3 (5 families). Three variants (αIIb: p.Arg1026Trp and p.Arg1026Gln and β3: p.Asp749His) were previously reported. The remaining (αIIb: p.Gly1007Val and β3: p.Thr746Pro, p.His748Pro and p.Arg760Cys) are new, expanding the αIIbβ3 defects associated with GTLS. The integration of the clinical and laboratory data allowed the identification of two GTLS subgroups, with distinct disease severity. Conclusions Previously reported ITGA2B and ITGB3 variants related to thrombocytopenia were clustered in a confined region of the membrane-proximal cytoplasmic domains, the inner membrane clasp. For the first time, variants are reported at the outer membrane clasp, at the transmembrane domain of αIIb, and at the membrane distal cytoplasmic domains of β3. This is the largest single-center series of inherited macrothrombocytopenia associated with αIIbβ3 variants published to date.

scholarly journals Softening and instability of natural slopes in highly fissured plastic clay shales

2006 ◽  
Vol 6 (4) ◽  
pp. 529-539 ◽  
Author(s):  
L. Picarelli ◽  
G. Urciuoli ◽  
A. Mandolini ◽  
M. Ramondini
Keyword(s):  
Laboratory Data ◽  
Field Observations ◽  
Plastic Clay ◽  
Clay Shales ◽  
Italian Apennines ◽  
First Time ◽  
Natural Slopes

Abstract. Softening is often considered to be the main cause of first-time slides in OC clay, but so far the mechanics of softening has not been satisfactorily explained. Bearing on laboratory data and field observations about landslides in tectonized highly plastic clay shales of Italian Apennines, the paper describes a process of soil weakening that could explain some failures of natural slopes.

Severe Pre-Eclampsia in Multiparous Women: Indication of an Environmental Triggering Agent?

1987 ◽  
Vol 32 (1) ◽  
pp. 8-10 ◽  
Author(s):  
D.C. Kilpatrick ◽  
E.C. Jazwinska ◽  
W.A. Liston ◽  
G.E. Smart
Keyword(s):  
Laboratory Data ◽  
Infectious Agent ◽  
Clinical Syndrome ◽  
Case Histories ◽  
First Case ◽  
Multiparous Women ◽  
History Of ◽  
Maternal Immune Response ◽  
First Time ◽  
Normotensive Pregnancy

Two case histories are described with conflicting implications for the etiopathogenesis of pre-eclampsia. In both, typical proteinuric pre-eclampsia developed despite a history of previous normotensive pregnancy. In the first case, the disease was associated with a change of husband, consistent with the view that pre-eclampsia arises from an inadequate maternal immune response to paternal antigens inherited by the fetus. The second case, however, concerned a woman who developed pre-eclampsia for the first time in her third pregnancy by the same reproductive partner. We conclude that either more than one underlying cause can result in the clinical syndrome of pre-eclampsia, or that pre-eclampsia is caused by an environmental factor. The possibility that pre-eclampsia may be initiated by an infectious agent is briefly explored in the light of the clinical histories described and well-established epidemiological, clinical and laboratory data.

An interactive bypass transition mechanism in wall-bounded flows

2008 ◽  
Vol 615 ◽  
pp. 345-369 ◽  
Author(s):  
F. SEDAT TARDU ◽  
RABIA NACEREDDINE ◽  
OLIVIER DOCHE
Keyword(s):  
Reynolds Shear Stress ◽  
Rapid Development ◽  
Three Dimensional ◽  
Streamwise Vortex ◽  
Transition Process ◽  
Wall Turbulence ◽  
Small Scale ◽  
Bypass Transition ◽  
Transition Mechanism ◽  
Turbulent Wall

The interaction between two localized disturbances is analysed in a subcritical channel flow through direct numerical simulations. The initial perturbations are in the form of two pairs of counter-rotating vortices. One of them interacts with the wall-normal vorticity layers set up near the wall, by locally compressing or stretching part of them through the straining motion it induces. The breakdown of spanwise symmetry leads to the rapid development of a new wall-normal vorticity patch that is tilted by the shear and rolls up into a new small-scale streamwise vortex. The process results in a localized turbulent spot at later stages of development. A detailed analysis is carried out to determine the role of different parameters entering the physics of the mechanism. Several critical thresholds that trigger the interactive bypass transition process are found and analysed. The similarity parameters resulting from the parametric investigation coincide well with those governing the self-sustaining Reynolds-shear-stress-producing eddies in the buffer layer of a fully developed turbulent wall flow. It is suggested that the mechanism we propose may play a role in the regeneration cycle of the near-wall turbulence-generating structures by bypassing the three-dimensional streak instability mechanism.

Mikrowellenspektrum, Struktur und l-Typ-Dublett-Aufspaltung der HCNO (Knallsäure)

1967 ◽  
Vol 22 (11) ◽  
pp. 1724-1737 ◽  
Author(s):  
Manfred Winnewisser ◽  
Hans Karl Bodenseh
Keyword(s):  
Ground State ◽  
Stark Effect ◽  
Coupling Constants ◽  
Vibrational Modes ◽  
Quadrupole Coupling ◽  
Bending Modes ◽  
First Time ◽  
O 11 ◽  
O 10 ◽  
Marked Dependence

The microwave spectra of unstable, gaseous fulminic acid H12C14N16O and five of its isotopically substituted species have been studied in the frequency range from 10 to 46 GHz. The spectrum of molecules in the ground vibrational state established the linearity of the chain HCNO. The following rotational constants B0 for the ground state were obtained:B0 (H12C14N16O) = 11 469.04 MHz, B0 (H12C14N17O) = 11 151.69 MHz,B0 (D12C14N16O) = 10 292.51 MHz, B0 (H12C14N18O) = 10 865.34 MHz,B0 (H13C14N16O) = 11 091.57 MHz, B0 (D13C14N16O) = 10 011.18 MHz.From these a combined r8- and r0-structure has been evaluated: r(C—H) = (1.027±0.001) A, r(C—N) = (1.161 ± 0.015) A, r(N—O) = (1.207±0.015) A.The rather large uncertainties in the C—N- and N—O-distances are due to the proximity of the N-atom to the center of gravity.It appears to be the first time that, in the same molecule, two different ι-type doublets (Δl=0, AJ= + 1) and their corresponding series of /-type doubling transitions (Al =2, ΔJ = 0), arising from the two degenerate bending modes (υ4=1 and v5=1), have been observed.The analysis of the two ι-type doubling series revealed a marked dependence of the /-type doubling constants q4 and q5 on higher powers of the angular momentum J. This J-dependence was found to be substantially different for the two vibrational modes.The doubling constants given in MHz areq4=23.6722 - (0.6139·10-3) J(J+1) + (0.1417·10-6) [J(J+1)]2-(0199·10-10) [J(J+1)]3,q5=34.6391 - (0.1623·10-3) J(J+1) + (1.00·10-9) [J(J+1)]2.The molecular dipole moment was determined from Stark-effect measurements on the J=0 → 1 transition in the ground state and found to be (3.06 ± 0.15) Debye. The nuclear quadrupole coupling constants for the 14N- and 170-nuclei can be given ase q Q (17O) = — (12.31 ± 0.12) MHz and | e q Q (14N) | ≦ 0.3 MHz.

scholarly journals Revealing capture sites and movements by strontium isotope analyses in bones of Caiman yacare in the Beni river floodplain, Bolivia

2021 ◽  
Author(s):  
Marc Pouilly ◽  
Sergio Gomez ◽  
Christophe Pecheyrann ◽  
Sylvain Berail ◽  
Gustavo Alvarez ◽  
...  
Keyword(s):  
Isotopic Ratio ◽  
Outer Part ◽  
High Fidelity ◽  
River Floodplain ◽  
Individual Life ◽  
Isotopic Variation ◽  
Or Groups ◽  
The Individual ◽  
First Time ◽  
Isotope Analyses

Studying the distribution of organisms and their movements is fundamental to understand population dynamics. Most studies indicated that crocodilians do not move around much but several studies demonstrated that some species showed movement patterns. Detection of these movements along the individual life is still a challenge. In this study we analyzed the variation of strontium isotopic ratio (87Sr/86Sr) in the femur bones of 70 Caiman yacare individuals caught in 16 sites located in five hydrological sectors of the Beni river floodplain in Bolivia. Our results demonstrated for the first time that such a methodology could yield indications about the capture sites and reconstruct individual life history. Analyses of the outer part of the femur of 70 individuals showed that capture sites could be differentiated between sectors and even between sites or groups of sites in each sector. Studies of complete 87Sr/86Sr profiles along the femur, representing entire life of the individual, were performed on 33 yacares. We found that most of the individuals did not show any significant isotopic variation throughout their lives. This absence of variation could result from a high fidelity to the birth site, and/or from an insignificant isotopic variation between the water bodies through which the animal has potentially moved. However, 24% of the analyzed individuals presented significant variations that can be considered as movements between different habitats. Based on the observed low proportion of moving yacares, we advocated that each water body should be considered an individual management unit.

scholarly journals Fermi surface and kink structures in $$\hbox {Sr}_{{4}}\hbox {Ru}_{{3}}\hbox {O}_{{10}}$$ revealed by synchrotron-based ARPES

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Prosper Ngabonziza ◽  
Emanuela Carleschi ◽  
Volodymyr Zabolotnyy ◽  
Amina Taleb-Ibrahimi ◽  
François Bertran ◽  
...  
Keyword(s):  
Fermi Surface ◽  
Fermi Level ◽  
Surface Topology ◽  
Photon Polarization ◽  
Strong Electron ◽  
Electron Phonon Coupling ◽  
Band Dispersion ◽  
Lattice Dynamic Calculation ◽  
First Time ◽  
O 10

AbstractThe low-energy electronic structure, including the Fermi surface topology, of the itinerant metamagnet $$\hbox {Sr}_{{4}}\hbox {Ru}_{{3}}\hbox {O}_{{10}}$$ Sr 4 Ru 3 O 10 is investigated for the first time by synchrotron-based angle-resolved photoemission. Well-defined quasiparticle band dispersions with matrix element dependencies on photon energy or photon polarization are presented. Four bands crossing the Fermi-level, giving rise to four Fermi surface sheets are resolved; and their complete topography, effective mass as well as their electron and hole character are determined. These data reveal the presence of kink structures in the near-Fermi-level band dispersion, with energies ranging from 30 to 69 meV. Together with previously reported Raman spectroscopy and lattice dynamic calculation studies, the data suggest that these kinks originate from strong electron–phonon coupling present in $$\hbox {Sr}_{{4}}\hbox {Ru}_{{3}}\hbox {O}_{{10}}$$ Sr 4 Ru 3 O 10 . Considering that the kink structures of $$\hbox {Sr}_{{4}}\hbox {Ru}_{{3}}\hbox {O}_{{10}}$$ Sr 4 Ru 3 O 10 are similar to those of the other three members of the Ruddlesden Popper structured ruthenates, the possible universality of strong coupling of electrons to oxygen-related phonons in $$\hbox {Sr}_{n+1}\hbox {Ru}_{{n}}\hbox {O}_{3n+1}$$ Sr n + 1 Ru n O 3 n + 1 compounds is proposed.

scholarly journals First reported outbreak of green tobacco sickness in Brazil

2010 ◽  
Vol 26 (12) ◽  
pp. 2263-2269 ◽  
Author(s):  
Patricia Pereira Vasconcelos de Oliveira ◽  
Camila Brederode Sihler ◽  
Lenildo de Moura ◽  
Deborah Carvalho Malta ◽  
Maria Célia de Albuquerque Torres ◽  
...  
Keyword(s):  
Risk Factors ◽  
High Performance ◽  
Laboratory Data ◽  
Signs And Symptoms ◽  
Dermal Absorption ◽  
Acute Intoxication ◽  
Matched Case ◽  
Independent Risk Factors ◽  
First Time ◽  
Control Study

Dermal absorption of nicotine by people harvesting tobacco may cause an acute intoxication called green tobacco sickness. Although Brazil is the second largest producer of tobacco in the world, green tobacco sickness had not been reported in the country to date. We conducted a 1:1 matched case-control study among persons involved in tobacco farming to determine the occurrence of green tobacco sickness in the northeast region of Brazil and to identify the risk factors involved. A case-patient was a person who received a diagnosis by health professional of acute intoxication during the study period and had a cotinine level over 10ng/mL detected by High Performance Liquid Chromatography. We identified 107 case-patients. The main signs and symptoms observed were dizziness, weakness, vomit, nausea and headache. Independent risk factors identified were being male, a non smoker and having worked in the harvest of tobacco leaves. Case-patients had higher median urinary cotinine levels than controls (p < 0.05). Epidemiological and laboratory data indicate for the first time the occurrence of green tobacco sickness in Brazil.

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