| 1. |
- Bilandi, R. N., et al.
(author)
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Calm-water performance of a boat with two swept steps at high-speeds : Laboratory measurements and mathematical modeling
- 2020
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In: Procedia Manufacturing. - : Elsevier B.V.. - 2351-9789. ; , s. 467-474
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Conference paper (peer-reviewed)abstract
- Laboratory measurements are performed to find the performance in calm water of a planing hull with two swept steps. Furthermore, a mathematical model, based on the 2D+T theory, is adapted to provide a fast and accurate simulation for performance prediction of this craft. The trim angle of the vessel is seen to reach to two peaks, one in pre-planing and on in the early planing speed, then converges to a small value around 2 degrees. A small wetted area is seen to appear near the chine of the middle body of the vessel at early planing speed. Laboratory measurements and mathematical computations are seen to be in good agreement, especially at very high-speeds. Overall, the mathematical model is found to be a useful tool for performance prediction of boats with swept steps, which can have different, but better performance in comparison with stepless and boats with transverse steps.
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| 2. |
- Björefeldt, Andreas, 1982, et al.
(author)
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Human cerebrospinal fluid promotes spontaneous gamma oscillations in the hippocampus in vitro
- 2020
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In: Hippocampus. - : Wiley. - 1050-9631 .- 1098-1063. ; 30:2, s. 101-113
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Journal article (peer-reviewed)abstract
- Gamma oscillations (30-80 Hz) are fast network activity patterns frequently linked to cognition. They are commonly studied in hippocampal brain slices in vitro, where they can be evoked via pharmacological activation of various receptor families. One limitation of this approach is that neuronal activity is studied in a highly artificial extracellular fluid environment, as provided by artificial cerebrospinal fluid (aCSF). Here, we examine the influence of human cerebrospinal fluid (hCSF) on kainate-evoked and spontaneous gamma oscillations in mouse hippocampus. We show that hCSF, as compared to aCSF of matched electrolyte and glucose composition, increases the power of kainate-evoked gamma oscillations and induces spontaneous gamma activity in areas CA3 and CA1 that is reversed by washout. Bath application of atropine entirely abolished hCSF-induced gamma oscillations, indicating critical contribution from muscarinic acetylcholine receptor-mediated signaling. In separate whole-cell patch clamp recordings from rat hippocampus, hCSF increased theta resonance frequency and strength in pyramidal cells along with enhancement of h-current (I-h) amplitude. We found no evidence of intrinsic gamma frequency resonance at baseline (aCSF) among fast-spiking interneurons, and this was not altered by hCSF. However, hCSF increased the excitability of fast-spiking interneurons, which likely contributed to gamma rhythmogenesis. Our findings show that hCSF promotes network gamma oscillations in the hippocampus in vitro and suggest that neuromodulators distributed in CSF could have significant influence on neuronal network activity in vivo.
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| 3. |
- Dashtimanesh, Abbas, et al.
(author)
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Effects of step configuration on hydrodynamic performance of one- and doubled-stepped planing flat plates : A numerical simulation
- 2020
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In: Proceedings of the Institution of Mechanical Engineers Part M: Journal of Engineering for the Maritime Environment. - : SAGE Publications. - 1475-0902 .- 2041-3084. ; 234:1, s. 181-195
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Journal article (peer-reviewed)abstract
- Categorized as one of high-speed marine vehicles, stepped planing hulls have the potential to reach relatively high speed in the sea by decreasing wetted surface. There were and still are some challenges in modeling of these vessels and design of ideal situation of steps. In the current study, a numerical-based method has been used to provide understanding about the effect of step height and its location on hydrodynamic characteristics of double-stepped planing plates. At the first step, one-stepped planing plate is numerically simulated. Results are compared against exiting numerical data, suggesting that results of the current numerical simulation are similar to results of previous numerical simulations. Then, double-stepped planing plates are modeled and pressure distribution, wetted length, free surface elevation and drag over lift ratio are computed. It is seen that, ventilation length behind the step and pressure coefficient are increased when step height of one- and a double-stepped planing plates are increased. It has been shown that, unlike an one-stepped planing plate, drag coefficient of a double-stepped planing plate can be increased when the step height is increased. The effects of the location of the second step on the performance of the planing plate have been explored, showing that this position plays a critical role on hydrodynamic forces. It is demonstrated that when the smallest possible lift force is produced by the middle-body, the plate shows the best performance (highest lift over drag ratio).
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| 4. |
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| 5. |
- Roshan, F., et al.
(author)
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Hull–propeller interaction for planing boats : a numerical study
- 2020
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In: Ships and Offshore Structures. - : Taylor and Francis Ltd.. - 1744-5302 .- 1754-212X. ; , s. 1-13
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Journal article (peer-reviewed)abstract
- Numerical simulations are performed to study the interaction between propeller and hull for two planing vessels: a hard-chine and a tunnelled craft. The numerical model used for reproduction of the problem is validated by comparing the obtained results against published data, showing that a morphing technique is more reliable compared to an overset one. It is demonstrated that propellers strongly affect the performance of a vessel by increasing trim angle and decreasing resistance, which are caused by a noticeable pressure reduction occurring near propellers. These changes are more significant for the case of a tunnelled hull since hydrodynamic pressure acting on the bottom of this vessel is larger compared to a hard-chine craft. While resistance of hulls is seen to be influenced by variation in the position of the propellers at early-planing mode, trim angle is seen to be insensitive to the position of propellers at all speeds.
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| 6. |
- Roshan, F., et al.
(author)
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Hydrodynamic characteristics of tunneled planing hulls in calm water
- 2020
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In: Brodogradnja. - : Brodarski Institute. - 0007-215X .- 1845-5859. ; 71:1, s. 19-38
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Journal article (peer-reviewed)abstract
- Tunneled planing hull is a special design of high speed craft which can reduce the frictional resistance to achieve higher velocities in high speeds. But, at lower speeds tunnels may lead to increase hull resistance. Therefore, tunneled planing hull design is an important issue which should be conducted with full prior information. In this study, a tunneled planing hull has numerically been studied in details using Star-CCM+ software. These simulations are based on Finite Volume Method (FVM) solution of Reynolds Averaged Navier-Stokes Equations (RANSE). Also, Volume of Fluid (VOF) method has been employed to obtain free surface variations, accurately. Morphing mesh approach has also been implemented to be able to simulate tunneled planing hull in two degrees of freedom in heave and pitch directions. Presented numerical setup has been validated by comparison of computed trim angle and hull resistant against the experimental results which have been presented by previous researchers. Afterwards, various physical phenomena around the considered tunneled planing hull as well as different physical parameters such as skin friction distribution, details of wetted surface area (total wetted surface, tunnel wetted surface, spray angle, keel and chain wetted length), shear and pressure drag, pressure distribution, wake pattern, and stream lines have been discussed, thoroughly. In this paper a new parameter as tunneled efficiency has been introduced based on obtained results. Tunnel efficiency shows appropriate speed range of planing hulls for using tunnel advantages in drag reduction. Presented results help designers to find new insight about the hydrodynamics of tunneled planing hulls.
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| 7. |
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| 8. |
- Vaid, Roshan, et al.
(author)
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Global loss of cellular m(6)A RNA methylation following infection with different SARS-CoV-2 variants
- 2023
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In: Genome Research. - : Cold Spring Harbor Laboratory. - 1088-9051 .- 1549-5469. ; 33:3, s. 299-313
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Journal article (peer-reviewed)abstract
- Insights into host-virus interactions during SARS-CoV-2 infection are needed to understand COVID-19 pathogenesis and may help to guide the design of novel antiviral therapeutics. N-6-Methyladenosine modification (m(6)A), one of the most abundant cellular RNA modifications, regulates key processes in RNA metabolism during stress response. Gene expression profiles observed postinfection with different SARS-CoV-2 variants show changes in the expression of genes related to RNA catabolism, including m(6)A readers and erasers. We found that infection with SARS-CoV-2 variants causes a loss of m(6)A in cellular RNAs, whereas m(6)A is detected abundantly in viral RNA. METTL3, the m(6)A methyltransferase, shows an unusual cytoplasmic localization postinfection. The B.1.351 variant has a less-pronounced effect on METTL3 localization and loss of m(6)A than did the B.1 and B.1.1.7 variants. We also observed a loss of m(6)A upon SARS-CoV-2 infection in air/liquid interface cultures of human airway epithelia, confirming that m(6)A loss is characteristic of SARS-CoV-2-infected cells. Further, transcripts with m(6)A modification are preferentially down-regulated postinfection. Inhibition of the export protein XPO1 results in the restoration of METTL3 localization, recovery of m(6)A on cellular RNA, and increased mRNA expression. Stress granule formation, which is compromised by SARS-CoV-2 infection, is restored by XPO1 inhibition and accompanied by a reduced viral infection in vitro. Together, our study elucidates how SARS-CoV-2 inhibits the stress response and perturbs cellular gene expression in an m(6)A-dependent manner.
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| 9. |
- van den Bosch, Ruben, et al.
(author)
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Evidence for absence of links between striatal dopamine synthesis capacity and working memory capacity, spontaneous eye-blink rate, and trait impulsivity
- 2023
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In: eLIFE. - : eLife Sciences Publications Ltd. - 2050-084X. ; 12
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Journal article (peer-reviewed)abstract
- Individual differences in striatal dopamine synthesis capacity have been associated with working memory capacity, trait impulsivity, and spontaneous eye-blink rate (sEBR), as measured with readily available and easily administered, ‘off-the-shelf’ tests. Such findings have raised the suggestion that individual variation in dopamine synthesis capacity, estimated with expensive and invasive brain positron emission tomography (PET) scans, can be approximated with simple, more pragmatic tests. However, direct evidence for the relationship between these simple trait measures and striatal dopamine synthesis capacity has been limited and inconclusive. We measured striatal dopamine synthesis capacity using [18F]-FDOPA PET in a large sample of healthy volunteers (N = 94) and assessed the correlation with simple, short tests of working memory capacity, trait impulsivity, and sEBR. We additionally explored the relationship with an index of subjective reward sensitivity. None of these trait measures correlated significantly with striatal dopamine synthesis capacity, nor did they have out-of-sample predictive power. Bayes factor analyses indicated the evidence was in favour of absence of correlations for all but subjective reward sensitivity. These results warrant caution for using these off-the-shelf trait measures as proxies of striatal dopamine synthesis capacity.
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