Dynamos with weakly convecting outer layers: implications for core-mantle boundary interaction

Convection in the Earth's core is driven much harder at the bottom than the top. This is partly because the adiabatic gradient steepens towards the top, partly because the spherical geometry means the area involved increases towards the top, and partly because compositional convection is driven by light material released at the lower boundary and remixed uniformly throughout the outer core, providing a volumetric sink of buoyancy. We have therefore investigated dynamo action of thermal convection in a Boussinesq fluid contained within a rotating spherical shell driven by a combination of bottom and internal heating or cooling. We first apply a homogeneous temperature on the outer boundary in order to explore the effects of heat sinks on dynamo action; we then impose an inhomogeneous temperature proportional to a single spherical harmonic Y2² in order to explore core-mantle interactions. With homogeneous boundary conditions and moderate Rayleigh numbers, a heat sink reduces the generated magnetic field appreciably; the magnetic Reynolds number remains high because the dominant toroidal component of flow is not reduced significantly. The dipolar structure of the field becomes more pronounced as found by other authors. Increasing the Rayleigh number yields a regime in which convection inside the tangent cylinder is strongly affected by the magnetic field. With inhomogeneous boundary conditions, a heat sink promotes boundary effects and locking of the magnetic field to boundary anomalies. We show that boundary locking is inhibited by advection of heat in the outer regions. With uniform heating, the boundary effects are only significant at low Rayleigh numbers, when dynamo action is only possible for artificially low magnetic diffusivity. With heat sinks, the boundary effects remain significant at higher Rayleigh numbers provided the convection remains weak or the fluid is stably stratified at the top. Dynamo action is driven by vigorous convection at depth while boundary thermal anomalies dominate in the upper regions. This is a likely regime for the Earth's core

On the formation of cyclones and anticyclones in a rotating fluid

It is commonly observed that the columnar vortices that dominate the large scales in homogeneous, rapidly rotating turbulence are predominantly cyclonic. This has prompted us to ask how this asymmetry arises. To provide a partial answer to this we look at the process of columnar vortex formation in a rotating fluid and, in particular, we examine how a localized region of swirl (an eddy) can convert itself into a columnar structure by inertial wave propagation. We show that, when the Rossby number (Ro) is small, the vortices evolve into columnar eddies through the radiation of linear inertial waves. When the Rossby number is large, on the other hand, no such column is formed. Rather, the eddy bursts radially outward under the action of the centrifugal force. There is no asymmetry between cyclonic and anticyclonic eddies for these two regimes. However, cyclones and anticyclones behave differently in the intermediate regime of Ro~1. Here we find that the transition from columnar vortex formation to radial bursting occurs at lower values of Ro for anticyclones, with the transition for anticyclones occurring at Ro~0.5, and that for cyclones at Ro~2. Thus, in a homogeneous turbulence experiment conducted at, say, Ro=1, we would expect to see more cyclones than anticyclones. The reason for this asymmetry at Ro~1 is explained

Isolation, identification and expression analysis of salt-induced genes in Suaeda maritima, a natural halophyte, using PCR-based suppression subtractive hybridization

<p>Abstract</p> <p>Background</p> <p>Despite wealth of information generated on salt tolerance mechanism, its basics still remain elusive. Thus, there is a need of continued effort to understand the salt tolerance mechanism using suitable biotechnological techniques and test plants (species) to enable development of salt tolerant cultivars of interest. Therefore, the present study was undertaken to generate information on salt stress responsive genes in a natural halophyte, <it>Suaeda maritima</it>, using PCR-based suppression subtractive hybridization (PCR-SSH) technique.</p> <p>Results</p> <p>Forward and reverse SSH cDNA libraries were constructed after exposing the young plants to 425 mM NaCl for 24 h. From the forward SSH cDNA library, 429 high quality ESTs were obtained. BLASTX search and TIGR assembler programme revealed overexpression of 167 unigenes comprising 89 singletons and 78 contigs with ESTs redundancy of 81.8%. Among the unigenes, 32.5% were found to be of special interest, indicating novel function of these genes with regard to salt tolerance. Literature search for the known unigenes revealed that only 17 of them were salt-inducible. A comparative analysis of the existing SSH cDNA libraries for NaCl stress in plants showed that only a few overexpressing unigenes were common in them. Moreover, the present study also showed increased expression of phosphoethanolamine N-methyltransferase gene, indicating the possible accumulation of a much studied osmoticum, glycinebetaine, in halophyte under salt stress. Functional categorization of the proteins as per the Munich database in general revealed that salt tolerance could be largely determined by the proteins involved in transcription, signal transduction, protein activity regulation and cell differentiation and organogenesis.</p> <p>Conclusion</p> <p>The study provided a clear indication of possible vital role of glycinebetaine in the salt tolerance process in <it>S. maritima</it>. However, the salt-induced expression of a large number of genes involved in a wide range of cellular functions was indicative of highly complex nature of the process as such. Most of the salt inducible genes, nonetheless, appeared to be species-specific. In light of the observations made, it is reasonable to emphasize that a comparative analysis of ESTs from SSH cDNA libraries generated systematically for a few halophytes with varying salt exposure time may clearly identify the key salt tolerance determinant genes to a minimum number, highly desirable for any genetic manipulation adventure.</p

A novel intra-body sensor for vaginal temperature monitoring

Over the years some medical studies have tried to better understand the internal behavior of human beings. Many researchers in this domain have been striving to find relationships between intra-vaginal temperature and certain female health conditions, such as ovulation and fertile period since woman’s intra-vaginal temperature is one of the body parameters most preferred in such studies. However, due to lack of a appropriate technology, medical research devoted to studying correlations of such body parameters with certain womans’ body phenomena could not obtain better results. This article presents the design and implementation of a novel intra-body sensor for acquisition and monitoring of intra-vaginal temperatures. This novel intra-body sensor provides data collection that is used for studying the relation between temperature variations and female health conditions, such as anticipation and monitoring of the ovulation period, detection of pregnancy contractions, preterm labor prevention, etc.. The motivation for this work focuses on the development of this new intra-body sensor that will represent a major step in medical technology. The novel sensor was tested and validated on hospitalized women as well as normal healthy women. Finally our medical team has attested to the accuracy, usability and performance of this novel intra-body sensor

A novel intra-body sensor for vaginal temperature monitoring

Over the years some medical studies have tried to better understand the internal behavior of human beings. Many researchers in this domain have been striving to find relationships between intra-vaginal temperature and certain female health conditions, such as ovulation and fertile period since woman’s intra-vaginal temperature is one of the body parameters most preferred in such studies. However, due to lack of a appropriate technology, medical research devoted to studying correlations of such body parameters with certain womans’ body phenomena could not obtain better results. This article presents the design and implementation of a novel intra-body sensor for acquisition and monitoring of intra-vaginal temperatures. This novel intra-body sensor provides data collection that is used for studying the relation between temperature variations and female health conditions, such as anticipation and monitoring of the ovulation period, detection of pregnancy contractions, preterm labor prevention, etc.. The motivation for this work focuses on the development of this new intra-body sensor that will represent a major step in medical technology. The novel sensor was tested and validated on hospitalized women as well as normal healthy women. Finally our medical team has attested to the accuracy, usability and performance of this novel intra-body sensor

G-Sense: a graphical interface for SENSE simulator

“Copyright © [2009] IEEE. Reprinted from First International Conference on Advances in System Simulation.ISBN:978-1-4244-4863-0. This material is posted here with permission of the IEEE. Internal or personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution must be obtained from the IEEE by writing to [email protected]. By choosing to view this document, you agree to all provisions of the copyright laws protecting it.”Wireless sensor networks greatly benefit from simulation before deployment, since some of these networks may contain thousands of nodes. The new challenges compared to traditional computer networks led to several approaches for network simulation, namely SENSE – Sensor Network Emulator and Simulator. However this approach presents a limited user interface, namely based on text, forcing users to have knowledge on C++ programming language. This paper presents a tool, called G-Sense, that greatly improves SENSE user friendliness, with graphical input of simulation parameters, save and load simulation features, and simulation results management with plot view. This new tool uses SENSE simulation engine in a transparent way, so the user may be focused on the simulation itself, not in the underlying simulation tool. We present G-Sense architecture, usability and extensive experiments for its validation. We believe that this tool will contribute for SENSE adoption for wireless sensor network simulation, clearly improving on its ease of use

Evaluation of Onion Genotypes for Growth and Bulb Yield in Mid Hill of Nepal

Experiments were conducted at Horticulture Research Division (HRD), Khumaltar, Lalitpur; and Horticulture Research Station (HRS), Kimugaun, Dailekh in 2017/18 to evaluate the high yielding open pollinated genotypes of onion in mid hills of both locations. &nbsp;Five onion genotypes namely AVON-1016, AVON-1027, AVON-1028, AVON-1052, AVON-1074 and AVON-1103 received from Asian Vegetable Research and Development Centre were evaluated with local check variety and recommended variety Red Creole in both locations in randomized complete block design with 4 replications. The main objective of the experiment is to findout the high yielding open pollinated onion genotypes for mid hill condition.The pooled analysis of data over locations showed significant differences on plant height, neck diameter, bulb diameter, weight of bulbs and adjusted bulb yield per hectare. &nbsp;&nbsp;Introduced genotypes AVON 1027 (38.83 t/ha), AVON 1052 (31.97 t/ha) and AVON 1028 (31.48 t/ha) produced significantly higher yield than recommended and commercially cultivated check variety Red Creole (27.04 t/ha). Therefore the genotype AVON 1027 can be selected as the best genotype for growing in mid hills of Nepa

Solid-state Fermentation for the Production of Poly(hydroxyalkanoates)

Poly(hydroxyalkanoates) (PHAs) can be synthesized by adopting different microbial fermentation strategies, of which submerged fermentation has been exploited largely. In the past few years, solid-state fermentation (SSF) has been reassessed as an alternative to submerged fermentation, and could be a possible strategy for the cost-effective production of PHAs. The capital investment for SSF is usually lower than that of submerged fermentation and the cost of raw materials for SSF would be cheap, since it uses waste agricultural residues. These positive factors make SSF a potential technique for PHAs production. However, this method is still too immature for commercialization. The major drawback to address is the proper maintenance of the culture conditions under SSF. The present review discusses the current developments in solid-state fermentation for the production of PHAs and addresses the various issues for its commercialization

Intra-body temperature monitoring using a biofeedback solution

“Copyright © [2010] IEEE. Reprinted from 2nd International Conference on eHealth, Telemedicine, and Social Medicine . ISBN: 978-0-7695-3950-8. This material is posted here with permission of the IEEE. Internal or personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution must be obtained from the IEEE by writing to [email protected]. By choosing to view this document, you agree to all provisions of the copyright laws protecting it.”Body Area Sensor can enable healthcare monitoring in an unobtrusive way. Medical and healthcare research has been striving to find relationships between core body temperature at female genitals and certain health conditions, such as ovulation period. This paper presents a solution for intra-body temperature monitoring based on a new intra-body sensor, communication and desktop application tool. This new biosensor provides data collection that may be used to study the relation between temperature variations and women health conditions, such as, ovulation period (for both natural contraception and in vitro fertilization purposes) among others. The motivation for this work focuses on the creation of this e-Health solution that will fill the gap we realize in medical technology. The proposal was tested and validated by a medical team and it was concluded that this new biosensor performs perfectly

Impacts of environmental change on agroecosystems and livelihoods in Annapurna Conservation Area, Nepal

© 2017 Elsevier B.V. To understand local perceptions of the impacts of environmental change in two mountain districts of Nepal — Myagdi and Mustang — between 2010 and 2014, a survey, focus groups, town hall meetings, and extensive consultation with local stakeholders were conducted, supplemented by analyses of soil, rainfall, and temperature data. Mountain people in Nepal shared their perceptions of environmental change in their everyday lives, including agricultural practices and tourism activities. While ordinary individuals welcome the construction of new roads, elites still prefer to maintain trails and the status quo. People are concerned about the introduction of mosquitoes, increases in insect pests and plant pathogens, and other vectors along with roads. Snowfall has decreased and rainfall has been unpredictable. Mean minimum winter temperatures have increased and the mountains are experiencing shorter winters and less snow accumulation, which threaten the livelihoods of people that depend on fresh water. While people with means are replacing their traditional homes with modern homes, that is beyond reach for average Mustangi citizens. Expansion and diversification of agriculture, adoption of sound soil management techniques in Marpha village of Mustang and Shikha village of Myagdi, and growing forest cover in Shikha are some indicators of enhanced community managed practices. The coping strategies and indigenous practices adopted by local people in the region against hardship and environmental changes could serve as examples in similar mountain settings elsewhere