Ancient Martian Floods in a Plausible Variable Climatic Environment as Revealed from the Sequential Growth of Allan Hills 84001 Carbonate Globules

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Onset of Thermogravitational Convection in a Ferrofluid Layer with Temperature Dependent Viscosity

The onset of thermogravitational convection in a horizontal ferrofluid layer is investigated with viscosity depending exponentially on temperature. The bounding surfaces of the ferrofluid layer are considered to be either stress free or rigid-ferromagnetic and insulated to temperature perturbations. The resulting eigenvalue problem is solved numerically using the Galerkin technique and also by a regular perturbation technique for different types of velocity boundary conditions, namely free-free, rigid-rigid, and lower rigid- upper free. It is observed that increasing the viscosity parameter, ΛΛ, and the magnetic number, M1M1, is to hasten the onset of ferroconvection, while the nonlinearity of fluid magnetization, M3M3, is found to have no influence on the stability of the system. The critical stability parameters are found to be the same in the limiting cases of either no magnetic forces or no buoyancy forces

Effect of Coriolis Force on Bénard–Marangoni Convection in a Rotating Ferrofluid Layer with MFD Viscosity

The simultaneous effect of Coriolis force due to rotation and magnetic field dependent (MFD) viscosity on the onset of Bénard-Marangoni convection in a horizontal ferrofluid layer in the presence of a uniform vertical magnetic field is studied. The lower boundary is rigid while the upper free boundary is open to the atmosphere and at which the temperature-dependent surface tension effect is allowed for. The Galerkin technique is employed to extract the critical stability parameters numerically. The results show that the onset of Bénard-Marangoni ferroconvection is delayed with an increase in the MFD viscosity parameter , Taylor number T a, magnetic susceptibility χ and Biot number Bi but opposite is the case with an increase in the value of magnetic numberM1 and nonlinearity of fluid magnetization M3. Further, increase inM1, M3 and decrease in , T a, χ and Bi is to decrease the size of the convection cells. Comparisons of results between the present and the existing ones are made under the limiting conditions and good agreement is found

Ferromagnetic convection in a rotating ferrofluid saturated porous layer

The effect of Coriolis force on the onset of ferromagnetic convection in a rotating horizontal ferrofluid satd. porous layer in the presence of a uniform vertical magnetic field is studied. The boundaries are considered to be either stress free or rigid. The modified Brinkman-​Forchheimer-​extended Darcy equation with fluid viscosity different from effective viscosity is used to characterize the fluid motion. The condition for the occurrence of direct and Hopf bifurcations is obtained anal. in the case of free boundaries, while for rigid boundaries the eigenvalue problem has been solved numerically using the Galerkin method. Contrary to their stabilizing effect in the absence of rotation, increasing the ratio of viscosities, Λ, and decreasing the Darcy no. Da show a partial destabilizing effect on the onset of stationary ferromagnetic convection in the presence of rotation, and some important observations are made on the stability characteristics of the system. Moreover, the similarities and differences between free-​free and rigid-​rigid boundaries in the presence of buoyancy and magnetic forces together or in isolation are emphasized in triggering the onset of ferromagnetic convection in a rotating ferrofluid satd. porous layer. For smaller Taylor no. domain, the stress-​free boundaries are found to be always more unstable than in the case of rigid boundaries. However, this trend is reversed at higher Taylor no. domain because the stability of the stress-​free case is increased more quickly than the rigid case

User guide for the Biosphere Isotope Domains GB (Version 1) dataset and web portal

This report is a user guide for the Biosphere Isotope Domains GB (V1) dataset, which includes (1) a GIS layer for strontium, sulphur and oxygen isotopes (2) datasets of strontium and sulphur isotope measurements from samples across the Great Britain - published separately and available via BGS and (3) a web portal for viewing and querying the data. A description of the data, methodology and assumptions used in the construction of the Biosphere Isotope Domains GB map is included in the associated publications for strontium (Evans, 2018) and sulphur (Chenery, 2018). The primary application of such datasets is for determining the provenance of skeletal material; although the data may also be of use in modern traceability studies of fauna and flora

A high-throughput approach developing lithium-niobium-tantalum oxides as electrolyte/cathode interlayers for high-voltage all-solid-state lithium batteries

The ever-increasing interest in sustainable mobility is driving the development of innovative batteries with increased energy densities relative to currently commercialized lithium-ion batteries. All-solid-state batteries using 5 V-class positive electrodes are one of those batteries due to their larger volumetric energy density and their superior durability. However, their power density tends to be limited by the large charge transfer resistance at their electrolyte/5 V-electrode interfaces; one explanation for this is the development of significant Li+ deficient layers at the interface. Here we propose a new interlayer material that would effectively resolve the Li+ deficient layers. The partially-crystallized Li56Nb22Ta22 oxide was identified using the molecular beam epitaxy (MBE) based high-throughput physical vapor deposition (HT-PVD) approach. Its higher ionic conductivity of 4.2 ?S cm?1 and higher permittivity of 165 when measured at 254 kHz, relative to those of conventional LiNbO3 interlayer (1.8 ?S cm?1 and 95, respectively) will be effective for fast charge transfer reactions at the electrolyte /cathode interfaces in 5 V-class all-solid-state batteries

Performance of distributed mechanisms for flow admission in wireless adhoc networks

Given a wireless network where some pairs of communication links interfere with each other, we study sufficient conditions for determining whether a given set of minimum bandwidth quality-of-service (QoS) requirements can be satisfied. We are especially interested in algorithms which have low communication overhead and low processing complexity. The interference in the network is modeled using a conflict graph whose vertices correspond to the communication links in the network. Two links are adjacent in this graph if and only if they interfere with each other due to being in the same vicinity and hence cannot be simultaneously active. The problem of scheduling the transmission of the various links is then essentially a fractional, weighted vertex coloring problem, for which upper bounds on the fractional chromatic number are sought using only localized information. We recall some distributed algorithms for this problem, and then assess their worst-case performance. Our results on this fundamental problem imply that for some well known classes of networks and interference models, the performance of these distributed algorithms is within a bounded factor away from that of an optimal, centralized algorithm. The performance bounds are simple expressions in terms of graph invariants. It is seen that the induced star number of a network plays an important role in the design and performance of such networks.Comment: 21 pages, submitted. Journal version of arXiv:0906.378

Motif Discovery through Predictive Modeling of Gene Regulation

We present MEDUSA, an integrative method for learning motif models of transcription factor binding sites by incorporating promoter sequence and gene expression data. We use a modern large-margin machine learning approach, based on boosting, to enable feature selection from the high-dimensional search space of candidate binding sequences while avoiding overfitting. At each iteration of the algorithm, MEDUSA builds a motif model whose presence in the promoter region of a gene, coupled with activity of a regulator in an experiment, is predictive of differential expression. In this way, we learn motifs that are functional and predictive of regulatory response rather than motifs that are simply overrepresented in promoter sequences. Moreover, MEDUSA produces a model of the transcriptional control logic that can predict the expression of any gene in the organism, given the sequence of the promoter region of the target gene and the expression state of a set of known or putative transcription factors and signaling molecules. Each motif model is either a $k$-length sequence, a dimer, or a PSSM that is built by agglomerative probabilistic clustering of sequences with similar boosting loss. By applying MEDUSA to a set of environmental stress response expression data in yeast, we learn motifs whose ability to predict differential expression of target genes outperforms motifs from the TRANSFAC dataset and from a previously published candidate set of PSSMs. We also show that MEDUSA retrieves many experimentally confirmed binding sites associated with environmental stress response from the literature.Comment: RECOMB 200