186 research outputs found
Unsteady Natural Convection in an Initially Stratified Air-Filled Trapezoidal Enclosure Heated from Below
Natural convection is intensively explored, especially in a valley-shaped trapezoidal enclosure, because of its broad presence in both technical settings and nature. This study deals with a trapezoidal cavity, which is initially filled with linearly stratified air. Although the sidewalls remain adiabatic, the bottom wall is heated, and the top wall is cooled. For the stratified fluid (air), the temperature of the fluid adjacent to the top and the bottom walls is the same as that of the walls. Natural convection in the trapezoidal cavity is simulated in two dimensions using numerical simulations, by varying Rayleigh numbers (Ra) from 100 to 108 with constant Prandtl number, Pr = 0.71, and aspect ratio, A = 0.5. The numerical results demonstrate that the development of natural convection from the beginning is dependent on the Rayleigh numbers. According to numerical results, the development of transient flow within the enclosure owing to the predefined conditions for the boundary may be categorized into three distinct stages: early, transitional, and steady or unsteady. The flow characteristics at each of the three phases and the impact of the Rayleigh number on the flow’s growth are quantified. Unsteady natural convection flows in the enclosure are described and validated by numerical results. In addition, heat transfer through the bottom and the top surfaces is described in this study.</jats:p
A computational study on fluid flow and heat transfer through a rotating curved duct with rectangular cross section
The understanding of fluid flow and heat transfer (HT) through a rotating curved duct (RCD) is important for different engineering applications. The available literature improved the understanding of the fluid flow and HT through a large-curvature rotating duct. However, the comprehensive knowledge of fluid flow and HT through an RCD with small curvature is little known. This numerical study aims to perform fluid flow characterization and HT through an RCD with curvature ratio 0.001. The spectral based numerical approach investigates the effects of rotation on fluid flow and HT for the Taylor number -1000≤TTTT≤1500. A constant pressure gradient force, the Dean number Dn = 100, and a constant buoyancy force parameter, the Grashof number Gr = 500 are used for the numerical simulation. Fortran code is developed for the numerical computations and Tecplot software is used for the post-processing purpose. The numerical study investigates steady solutions and a structure of two-branches of steady solutions is obtained for positive rotation. The transient solution reports the transitional flow patterns and HT through the rotating duct, and two- to four-vortex solutions are observed. In case of negative rotation, time-dependent solutions show that the Coriolis force exhibits an opposite effect to that of the curvature so that the flow characteristics exhibit various flow instabilities. The numerical result shows that convective HT is increased with the increase of rotation and highly complex secondary flow patterns influence the overall HT from the heated wall to the fluid. To validate the numerical results, a comparison with the experimental data is provided, which shows that a good agreement is attained between the numerical and experimental investigations
Phenomenology of Light Sneutrino Dark Matter in cMSSM/mSUGRA with Inverse Seesaw
We study the possibility of a light Dark Matter (DM) within a constrained
Minimal Supersymmetric Standard Model (cMSSM) framework augmented by a SM
singlet-pair sector to account for the non-zero neutrino masses by inverse
seesaw mechanism. Working within a 'hybrid' scenario with the MSSM sector fixed
at high scale and the singlet neutrino sector at low scale, we find that,
contrary to the case of the usual cMSSM where the neutralino DM cannot be very
light, we can have a light sneutrino DM with mass below 100 GeV satisfying all
the current experimental constraints from cosmology, collider as well as
low-energy experiments. We also note that the supersymmetric inverse seesaw
mechanism with sneutrino as the lightest supersymmetric partner can have
enhanced same-sign dilepton final states with large missing transverse energy
(mET) coming from the gluino- and squark-pair as well as the squark-gluino
associated productions and their cascade decay through charginos. We present a
collider study for the same-sign dilepton+jets+mET signal in this scenario and
propose some distinctions with the usual cMSSM. We also comment on the
implications of such a light DM scenario on the invisible decay width of an 125
GeV Higgs boson.Comment: 24 pages, 4 figures, 7 tables; matches published versio
Syntaxin 16 is a master recruitment factor for cytokinesis
Recently it was shown that both recycling endosome and endosomal sorting complex required for transport (ESCRT) components are required for cytokinesis, in which they are believed to act in a sequential manner to bring about secondary ingression and abscission, respectively. However, it is not clear how either of these complexes is targeted to the midbody and whether their delivery is coordinated. The trafficking of membrane vesicles between different intracellular organelles involves the formation of soluble N-ethylmaleiÂmide–sensitive factor attachment protein receptor (SNARE) complexes. Although membrane traffic is known to play an important role in cytokinesis, the contribution and identity of intracellular SNAREs to cytokinesis remain unclear. Here we demonstrate that syntaxin 16 is a key regulator of cytokinesis, as it is required for recruitment of both recycling endosome–associated Exocyst and ESCRT machinery during late telophase, and therefore that these two distinct facets of cytokinesis are inextricably linked
Molecular, spectroscopic, and magnetic properties of cobalt(II) complexes with heteroaromatic N(O)-donor ligands
New [Co(SCN)2(L)4/2] complexes, where
L = b-pic (1), pyCH2OH (2), py(CH2)3OH (3), 1,2,4-
triazolo[1,5-a]pyrimidine (4), [CoCl2(urotrop)2] (5), and
[Co(DMIM)3]Cl2 H2O (6) where urotrop = hexamethylenetetramine
and DMIM = 2,20-bis(4,5-dimethylimidazolyl)
were synthesized in simple reactions of CoCl2 6H2O
with ammonia thiocyanate and pyridine type ligands or
urotropine and diimidazolyl ligands with cobalt(II) chloride
in methanol solutions. The orthorhombic crystallization
for (1), (2), and (4), the monoclinic one for (3) and (5)
as well as the hexagonal one for (6) were found. The plots
of the overlap population density-of-states indicated nonbonding
character of the interactions between pyridine
derivatives ligands and cobalt(II) ions in the complexes
(1)–(4). The electronic spectra showed almost perfect
octahedral complex in the case of (6). The magnetic susceptibility
measurements revealed paramagnetic behavior
with low values of the Curie–Weiss temperature, positive
for complex (5) and negative for the other ones, although
the transition to collective magnetic state at low temperatures
for (4) and (5) was evidenced by an observation of
antiferromagnetic coupling with Ne´el temperature of 4.5 K
and the ferromagnetic one with Curie temperature of 10 K,
respectively
Therapeutic and immunomodulatory activities of short-course treatment of murine visceral leishmaniasis with KALSOMEâ„¢10, a new liposomal amphotericin B
Visceral leishmaniasis (VL), a potentially fatal disease, is most prevalent in the Indian subcontinent,
East Africa and South America. Since the conventional antileishmanial drugs have many limitations we evaluated a
new ergosterol rich liposomal amphotericin B formulation, KALSOMEâ„¢10 for its leishmanicidal efficacy, tolerability
and immunomodulatory activity. Normal healthy mice were treated with 3.5 mg/kg single and 7.5 mg/kg single and double doses ofKALSOMEâ„¢10. Liver and kidney function tests were performed fourteen days after treatment. Next, normal mice were infected with Leishmania donovani amastigotes. Two months post infection they were treated with the above
mentioned doses of KALSOMEâ„¢10 and sacrificed one month after treatment for estimation of parasite burden in
the liver and spleen by Limiting Dilution Assay. Leishmanial antigen stimulated splenocyte culture supernatants were collected for cytokine detection through ELISA. Flow cytometric studies were performed on normal animals treated with KALSOMEâ„¢10, Amphotericin B (AmB) and AmBiosome to compare their immunomodulatory activities.
The drug was found to induce no hepato- or nephrotoxicities at the studied doses. Moreover, at all doses,
it led to significant reduction in parasite burden in two month infected BALB/c mice, with 7.5 mg/kg double dose
resulting in almost complete clearance of parasites from both liver and spleen. Interestingly, the drug at 7.5 mg/kg
double dose could almost completely inhibit the secretion of disease promoting cytokines, IL-10 and TGFβ, and
significantly elevate the levels of IFNγ and IL-12, cytokines required for control of the disease. Mice treated with KALSOME™10 showed elevated levels of IFNγ and suppressed IL-10 secretion from both CD4+ and CD8+ subsets
of T cells, as well as from culture supernatants of splenocytes, compared to that of normal, AmB and AmBisome
treated animal Treatment of infected mice with 7.5 mg/kg double dose of KALSOMEâ„¢10 was safe and effective in
clearing the parasites from the sites of infection. The drug maintains the inherent immunomodulatory activities of
AmB by effectively suppressing disease promoting cytokines IL-10 and TGFβ, thereby boosting IL-12 and IFNγ levels.
This emphasizes KALSOMEâ„¢10 as a promising drug alternative for lifelong protection from VL
Exploring novel correlations in trilepton channels at the LHC for the minimal supersymmetric inverse seesaw model
We investigate signatures of the minimal supersymmetric inverse seesaw model
at the large hadron collider (LHC) with three isolated leptons and large
missing energy (3\ell + \mET or 2\ell + 1\tau + \mET, with \ell=e,\mu) in the
final state. This signal has its origin in the decay of chargino-neutralino
(\chpm1\ntrl2) pair, produced in pp collisions. The two body decays of the
lighter chargino into a charged lepton and a singlet sneutrino has a
characteristic decay pattern which is correlated with the observed large
atmospheric neutrino mixing angle. This correlation is potentially observable
at the LHC by looking at the ratios of cross sections of the trilepton + \mET
channels in certain flavour specific modes. We show that even after considering
possible leading standard model backgrounds these final states can lead to
reasonable discovery significance at the LHC with both 7 TeV and 14 TeV
center-of-mass energy.Comment: 28 pages, 9 .eps figures. 3 new figures and discussions on LHC
observables added, minor modifications in text and in the abstract, 23 new
references added, matches with the published version in JHE
Optimizing the procedure of grain nutrient predictions in barley via hyperspectral imaging
Hyperspectral imaging enables researchers and plant breeders to analyze various traits of interest like nutritional value in high throughput. In order to achieve this, the optimal design of a reliable calibration model, linking the measured spectra with the investigated traits, is necessary. In the present study we investigated the impact of different regression models, calibration set sizes and calibration set compositions on prediction performance. For this purpose, we analyzed concentrations of six globally relevant grain nutrients of the wild barley population HEB-YIELD as case study. The data comprised 1,593 plots, grown in 2015 and 2016 at the locations Dundee and Halle, which have been entirely analyzed through traditional laboratory methods and hyperspectral imaging. The results indicated that a linear regression model based on partial least squares outperformed neural networks in this particular data modelling task. There existed a positive relationship between the number of samples in a calibration model and prediction performance, with a local optimum at a calibration set size of ~40% of the total data. The inclusion of samples from several years and locations could clearly improve the predictions of the investigated nutrient traits at small calibration set sizes. It should be stated that the expansion of calibration models with additional samples is only useful as long as they are able to increase trait variability. Models obtained in a certain environment were only to a limited extent transferable to other environments. They should therefore be successively upgraded with new calibration data to enable a reliable prediction of the desired traits. The presented results will assist the design and conceptualization of future hyperspectral imaging projects in order to achieve reliable predictions. It will in general help to establish practical applications of hyperspectral imaging systems, for instance in plant breeding concepts
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