2,811 research outputs found
Local orientations of fluctuating fluid interfaces
Thermal fluctuations cause the local normal vectors of fluid interfaces to
deviate from the vertical direction defined by the flat mean interface
position. This leads to a nonzero mean value of the corresponding polar tilt
angle which renders a characterization of the thermal state of an interface.
Based on the concept of an effective interface Hamiltonian we determine the
variances of the local interface position and of its lateral derivatives. This
leads to the probability distribution functions for the metric of the interface
and for the tilt angle which allows us to calculate its mean value and its mean
square deviation. We compare the temperature dependences of these quantities as
predicted by the simple capillary wave model, by an improved phenomenological
model, and by the microscopic effective interface Hamiltonian derived from
density functional theory. The mean tilt angle discriminates clearly between
these theoretical approaches and emphasizes the importance of the variation of
the surface tension at small wave lengths. Also the tilt angle two-point
correlation function is determined which renders an additional structural
characterization of interfacial fluctuations. Various experimental accesses to
measure the local orientational fluctuations are discussed.Comment: 29 pages, 12 figure
Wind reversals in turbulent Rayleigh-Benard convection
The phenomenon of irregular cessation and subsequent reversal of the
large-scale circulation in turbulent Rayleigh-B\'enard convection is
theoretically analysed. The force and thermal balance on a single plume
detached from the thermal boundary layer yields a set of coupled nonlinear
equations, whose dynamics is related to the Lorenz equations. For Prandtl and
Rayleigh numbers in the range and 10^{7} \leq
\Ra \leq 10^{12}, the model has the following features: (i) chaotic reversals
may be exhibited at Ra ; (ii) the Reynolds number based on the
root mean square velocity scales as \Re_{rms} \sim \Ra^{[0.41 ...
0.47]} (depending on Pr), and as
(depending on Ra); and (iii) the mean reversal frequency follows an effective
scaling law \omega / (\nu L^{-2}) \sim \Pr^{-(0.64 \pm 0.01)} \Ra^{0.44 \pm
0.01}. The phase diagram of the model is sketched, and the observed
transitions are discussed.Comment: 4 pages, 5 figure
Intravitreal bevacizumab for the treatment of macular oedema secondary to branch retinal vein occlusion
Purpose: To evaluate the effect of intravitreal bevacizumab (Avastin) injections on visual acuity (VA) and foveal retinal thickness in patients with macular oedema secondary to branch retinal vein occlusion.Methods: A prospective, non-comparative, consecutive, interventional case series of 34 patients. Patients received repeated intravitreal injections of 1.25 mg bevacizumab. Main outcome measures were VA (Snellen charts and ETDRS) and retinal thickness (optical coherence tomography measurements) in a follow-up period of 6 months.Results: Patients presented at a mean age of 69 years (range 44--86). Mean duration of symptoms was 40 weeks (range 1--300). Mean (SD) VA at baseline was 0.79 (0.39) logMAR, improving to 0.51 (0.34) logMAR at 6 months (p = 0.009). Mean number of letters on the ETDRS chart at baseline was 45.3 (19.0), improving to 60.6 (19.9) at 6 months (p = 0.003). Mean (SD) retinal thickness at baseline was 474 (120) \textgreekmm, declining to 316 (41) \textgreekmm at 6 months.Conclusion: Intravitreal injection of 1.25 mg bevacizumb appears to be an effective treatment option for branch retinal vein occlusion
Keberadaan Mikroba Pada Bakso Ikan Asap Cair, Yang Dikemas Dalam Retortable Pouch, Dipasteurisasi Dan Disimpan Pada Temperatur Ruang
A research has been done to assess the presence of microbes and the shelf life of fish balls dipped in liquid smoke, packed in retortable pouch, pasteurized, and stored at room temperature. The method used in this research is an experimental method that revealed the facts based on existing problems through hypothesis testing. Parameters assessed are Total Plate Count (TPC), total Salmonella, total coliforms and E. coli, total vibrio, water content, and pH. Fish balls were pasteurized in 85ºC and stored in room temperature for 0, 3, 6, and 9 days, and were pasteurized at 100°C and storage in room temperature for 0, 9, 18, and 27 days. The results shown that all pathogen were negative, but based on Indonesian standard (SNI 01-7266-1-2006) especially TPC value, fish balls were packaged in retortable pouch and without pasteurized is no longer acceptable for consumption after 3 days of storage, and fish balls were packaged in retortable pouch and pasteurized at 85ºC no longer acceptable for consumed after 6 days of storage. While the fish balls are packaged in retortable pouch and pasteurized at 100°C is no longer acceptable for consumed after 18 days of storage. Keyword: Retortable Pouch, Pasteurization, Pathogens. Penelitian ini bertujuan untuk mengetahui keberadaan mikroba dan daya awet bakso ikan yang direndam dalam asap cair dan dikemas dalam Retortable pouch, dipasteurisasi, dan disimpan pada temperatur ruang. Metode yang digunakan dalam penelitian ini adalah metode eksperimen untuk menguji hipotesa. Parameter yang diamati yaitu Angka Lempeng Total (ALT), Salmonella, total koliform dan E.coli, total vibrio, analisa kadar air, dan nilai pH. Bakso ikan asap cair yang dipasteurisasi pada 85ºC, disimpan pada temperatur ruang selama 0, 3, 6, dan 9 hari, dan yang dipasteurisasi pada 100ºC, disimpan pada temperatur ruang selama 0,9,18, dan 27 hari. Hasil penelitian menunjukkan bahwa bakso ikan yang dikemas dalam Retortable pouch, tanpa dipasteurisasi sudah tidak layak lagi untuk dikonsumsi setelah penyimpanan 3 hari, dan bakso ikan yang dikemas dalam Retortable pouch dan dipasteurisasi pada 85ºC sudah tidak layak lagi untuk dikonsumsi setelah penyimpanan 6 hari. Bakso ikan yang dikemas dalam Retortable pouch, dan dipasteurisasi pada 100ºC nanti tidak layak lagi dikonsumsi setelah penyimpanan 18 hari
Polymerisable octahedral rhenium cluster complexes as precursors for photo/electroluminescent polymers
New polymerisable photoluminescent octahedral rhenium cluster complexes trans-[{Re₆Q₈}(TBP)₄VB)₂] (Q = S or Se; TBP – p-tert-butylpyridine; VB – vinyl benzoate) have been synthesised, characterised and used to construct rhe-nium cluster-organic polymer hybrid materials. These novel polymer systems are solution-processable and the rhenium clusters retain their photoluminescent properties within the polymer environment. Notably, when the rhenium cluster complexes are incorporated into the matrix of the electroluminescent polymer poly(N-vinylcarbazole), the resultant cluster polymer hybrid combined properties of both components and was used successfully in the construc-tion of a polymer light emitting diode (PLED). These prototype devices are the first PLEDs to incorporate octahedral rhenium clusters and provide the first direct evidence of the electroluminescent properties of rhenium clusters and indeed, to the best of our knowledge, of any member of the family of 24-electron hexanuclear cluster complexes of molybdenum, tungsten or rhenium
Endothelial preconditioning by transient oxidative stress reduces inflammatory responses of cultured endothelial cells to TNF-α
Brief episodes of ischemia can render an organ resistant to subsequent severe ischemia. This ‘ischemic preconditioning’ is ascribed to various mechanisms, including oxidative stress. We investigated whether preconditioning exists on an endothelial level. Human umbilical vein endothelial cells (HUVECs) were transiently confronted with oxidative stress (1 mM H2O2, 5 min). Adhesion molecules ICAM-1 and E-selectin and release of cytokines IL-6 and IL-8 to subsequent stimulation with TNF-α (2.5 ng/ml, 4 h) were measured (flow cytometry and immunoassay), as were nuclear translocation of the transcription factor NFkB (Western blotting, confocal microscopy) and redox status of HUVECs (quantification of glutathione by HPLC). TNF-α elevated IL-6 in the cell supernatant from 8.8 ± 1 to 41 ± 3 pg/ml and IL-8 from 0.5 ± 0.03 to 3 ± 0.2 ng/ml. ICAM-1 was increased threefold and E-selectin rose eightfold. Oxidative stress (decrease of glutathione by 50%) reduced post-TNF-α levels of IL-6 to 14 ± 3 and IL-8 to 1 ± 0.2; the rise of ICAM-1 was completely blocked and E-selectin was only doubled. The anti-inflammatory effects of preconditioning via oxidative stress were paralleled by reduction of the translocation of NFkB on stimulation with TNF-α, and antagonized by the intracellular radical scavenger N-acetylcysteine. ‘Anti-inflammatory preconditioning’ of endothelial cells by oxidative stress may account for the inhibitory effects of preconditioning on leukocyte adhesion in vivo
Flow reversals in thermally driven turbulence
We analyze the reversals of the large scale flow in Rayleigh-B\'enard
convection both through particle image velocimetry flow visualization and
direct numerical simulations (DNS) of the underlying Boussinesq equations in a
(quasi) two-dimensional, rectangular geometry of aspect ratio 1. For medium
Prandtl number there is a diagonal large scale convection roll and two smaller
secondary rolls in the two remaining corners diagonally opposing each other.
These corner flow rolls play a crucial role for the large scale wind reversal:
They grow in kinetic energy and thus also in size thanks to plume detachments
from the boundary layers up to the time that they take over the main, large
scale diagonal flow, thus leading to reversal. Based on this mechanism we
identify a typical time scale for the reversals. We map out the Rayleigh number
vs Prandtl number phase space and find that the occurrence of reversals very
sensitively depends on these parameters.Comment: 4 pages, 4 figure
Boundary layer structure in turbulent thermal convection and its consequences for the required numerical resolution
Results on the Prandtl-Blasius type kinetic and thermal boundary layer
thicknesses in turbulent Rayleigh-B\'enard convection in a broad range of
Prandtl numbers are presented. By solving the laminar Prandtl-Blasius boundary
layer equations, we calculate the ratio of the thermal and kinetic boundary
layer thicknesses, which depends on the Prandtl number Pr only. It is
approximated as for and as for
, with . Comparison of the Prandtl--Blasius velocity
boundary layer thickness with that evaluated in the direct numerical
simulations by Stevens, Verzicco, and Lohse (J. Fluid Mech. 643, 495 (2010))
gives very good agreement. Based on the Prandtl--Blasius type considerations,
we derive a lower-bound estimate for the minimum number of the computational
mesh nodes, required to conduct accurate numerical simulations of moderately
high (boundary layer dominated) turbulent Rayleigh-B\'enard convection, in the
thermal and kinetic boundary layers close to bottom and top plates. It is shown
that the number of required nodes within each boundary layer depends on Nu and
Pr and grows with the Rayleigh number Ra not slower than \sim\Ra^{0.15}. This
estimate agrees excellently with empirical results, which were based on the
convergence of the Nusselt number in numerical simulations
Transcriptional responses of soybean aphids to sublethal insecticide exposure
Insecticides are a key tool in the management of many insect pests of agriculture, including soybean aphids. The selection imposed by insecticide use has often lead to the evolution of resistance by the target pest through enhanced detoxification mechanisms. We hypothesised that exposure of insecticide-susceptible aphids to sublethal doses of insecticides would result in the up-regulation of genes involved in detoxification of insecticides, revealing the genes upon which selection might act in the field. We used the soybean aphid biotype 1 reference genome, version 6.0 as a reference to analyze RNA-Seq data. We identified multiple genes with potential detoxification roles that were up-regulated 12 h after sublethal exposure to esfenvalerate or thiamethoxam. However, these genes were part of a dramatic burst of differential gene expression in which thousands of genes were up- or down-regulated, rather than a defined response to insecticides. Interestingly, the transcriptional burst observed at 12 h s declined dramatically by 24-hrs post-exposure, suggesting a general stress response that may become fine-tuned over time.
Includes Supplementary Materials
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