5,391 research outputs found
Cropping in Arid Area Greenhouse
In hot, arid regions, yields are low and unstable, growing season limited to one. Greenhouses can stabilize and improve yields and extend seasons. But their adoption is impeded by the requirement of large amount of water for (evaporative) cooling. Arid Area Greenhouse (AAG) is being developed to reduce or eliminate this need by employing earth-tube-heat-exchanger (ETHE). A prototype AAG was installed in the year 2002 at village Kothara (ƒ� 23�X 14 N, ƒ� 68�X 45 E, at 21 m a.s.l.). AAG is of 20 X 6 X 3.5 m size. ETHE is buried 3m deep and coupled to AAG in closed-loop. ETHE provides 20 air changes per hour. There is provision of closable vents - two along the base of long sides and one along the ridge. A retractable shading curtain is provided over the roof. By now five rounds of cropping have been done. ETHE was able to heat the greenhouse from 9�X C to 22-23�X C in half hour in the cold winter nights. Static ventilation along with shading was effective for day time control till early March. Subsequently ETHE was operated. It limited the greenhouse temperature gain to just 2.5�X C. Yield of tomato was 1.5 to 2 times, water used 44% of that in open-field. Water used was mostly for plants, only a small part was for foggers which were some times needed as supplement. ETHE and natural ventilation hold promise as environmental control devices for greenhouses in hot arid regions.
Metallo-Anti-aromatic Al4Na4 and Al4Na3- compounds: A theoretical investigation
We propose a theoretical investigation in this paper to understand the
bonding and structural properties of neutral Al4Na4 and anion Al4Na3- clusters.
We show that the Al4 species in Al4Na4 and Al4Na3- clusters is a rectangular
planar structure with alternate pi-bonds and hence satisfying the basic
criteria for anti-aromaticity. We prove that the Al4Na4 and Al4Na3- clusters
are metallo-anti-aromatic compounds
Structural, electronic and bonding properties of zeolite Sn-Beta: A periodic density functional theory study
The structural, electronic and the bonding properties of the Sn-BEA are
investigated by using the periodic density functional theory. Each of the 9
different T-sites in the BEA were substituted by the Sn atom and all the 9
geometries were completely optimized using the plane wave basis set in
conjunction with the ultra-soft pseudopotential. On the basis of the structural
and the electronic properties, it has been demonstrated that the substitution
of the Sn atom in the BEA framework is an endothermic process and hence the
incorporation of the Sn in the BEA is limited. The lowest unoccupied molecular
orbitals (LUMO) energies have been used to characterize the Lewis acidity of
each T-site. On the basis of the relative cohesive energy and the LUMO energy,
T2 site is shown to be the most favorable site for the substitution of Sn atom
in the BEA framework.Comment: 17 pages, 5 figures, 2 Table
Resolving RAD51C function in late stages of homologous recombination
DNA double strand breaks are efficiently repaired by homologous recombination. One of the last steps of this process is resolution of Holliday junctions that are formed at the sites of genetic exchange between homologous DNA. Although various resolvases with Holliday junctions processing activity have been identified in bacteriophages, bacteria and archaebacteria, eukaryotic resolvases have been elusive. Recent biochemical evidence has revealed that RAD51C and XRCC3, members of the RAD51-like protein family, are involved in Holliday junction resolution in mammalian cells. However, purified recombinant RAD51C and XRCC3 proteins have not shown any Holliday junction resolution activity. In addition, these proteins did not reveal the presence of a nuclease domain, which raises doubts about their ability to function as a resolvase. Furthermore, oocytes from infertile Rad51C mutant mice exhibit precocious separation of sister chromatids at metaphase II, a phenotype that reflects a defect in sister chromatid cohesion, not a lack of Holliday junction resolution. Here we discuss a model to explain how a Holliday junction resolution defect can lead to sister chromatid separation in mouse oocytes. We also describe other recent in vitro and in vivo evidence supporting a late role for RAD51C in homologous recombination in mammalian cells, which is likely to be resolution of the Holliday junction
The usage of Oṭu, Ōṭu Urupu found in Thirukkural
Tirukkural is considered to be the most important book among the Patinen kilkkanakku book. Tirukkural explains the basic qualities necessary for humans to live harmoniously in their inner lives and to live with pleasure, harmony, and well-being in their outer lives. Similarly, the verrumai urupu is an important element in Tamil grammar. Tolkappiyar defines verrumai urupu as eight. In such verrumai urupu, the third verrumai urupu has five terms. Its karutta or karuvipporul consists of two terms, al and an. Both are synonymous. The Utanikalccip consists of three terms, oṭu, ōṭu and uṭaṉ. All three give the same meaning. Therefore, the main objective of this study is to identify and explain the use of different forms of oṭu and ōṭu in tirukkural. This study was carried out with a qualitative approach. In this way, this research has been carried out in a descriptive approach using books, and research articles suitable for library research. All information has been analyzed based on the objective of the study. The research data has been classified according to the purpose of the study and analyzed in the text analysis method. Based on that, 1330 tirukkural 24 kural oṭu and ōṭu found An explanation is also given for the eight kural selected in it. Through this study, it is possible to know the usage of oṭu and ōṭu in tirukkuraḷ
Isothermal Shock Wave in Magnetogasdynamics
The problem of propagation of a plane isothermal discontinuity (shock) wave in a homogeneous semi-infinite body of a perfect gas, in the presence of amagnetic field have been solved. It has been shown that under certain definiteconditions, the density p at the wave front may be arbitrarily high for a singlecompression pulse. A certain class of solutions of the present problem for a nonhomogeneous semi-infinite body have been derived. Such solutions are expected to be of great importance in compression problems of plasma
Differentiation and Distribution of Marrow Stem Cells in Flex-Flow Environments Demonstrate Support of the Valvular Phenotype
For treatment of critical heart valve diseases, prosthetic valves perform fairly well in most adults; however, for pediatric patients, there is the added requirement that the replacement valve grows with the child, thus extremely limiting current treatment options. Tissue engineered heart valves (TEHV), such as those derived from autologous bone marrow stem cells (BMSCs), have the potential to recapitulate native valve architecture and accommodate somatic growth. However, a fundamental pre-cursor in promoting directed integration with native tissues rather than random, uncontrolled growth requires an understanding of BMSC mechanobiological responses to valve-relevant mechanical environments. Here, we report on the responses of human BMSC-seeded polymer constructs to the valve-relevant stress states of: (i) steady flow alone, (ii) cyclic flexure alone, and (iii) the combination of cyclic flexure and steady flow (flex-flow). BMSCs were seeded onto a PGA: PLLA polymer scaffold and cultured in static culture for 8 days. Subsequently, the aforementioned mechanical conditions, (groups consisting of steady flow alone-850ml/min, cyclic flexure alone-1 Hz, and flex-flow-850ml/min and 1 Hz) were applied for an additional two weeks. We found samples from the flex-flow group exhibited a valve-like distribution of cells that expressed endothelial (preference to the surfaces) and myofibroblast (preference to the intermediate region) phenotypes. We interpret that this was likely due to the presence of both appreciable fluid-induced shear stress magnitudes and oscillatory shear stresses, which were concomitantly imparted onto the samples. These results indicate that flex-flow mechanical environments support directed in vitro differentiation of BMSCs uniquely towards a heart valve phenotype, as evident by cellular distribution and expression of specific gene markers. A priori guidance of BMSC-derived, engineered tissue growth under flex-flow conditions may serve to subsequently promote controlled, engineered to native tissue integration processes in vivo necessary for successful long-term valve remodeling
LLM-Assist: Enhancing Closed-Loop Planning with Language-Based Reasoning
Although planning is a crucial component of the autonomous driving stack,
researchers have yet to develop robust planning algorithms that are capable of
safely handling the diverse range of possible driving scenarios. Learning-based
planners suffer from overfitting and poor long-tail performance. On the other
hand, rule-based planners generalize well, but might fail to handle scenarios
that require complex driving maneuvers. To address these limitations, we
investigate the possibility of leveraging the common-sense reasoning
capabilities of Large Language Models (LLMs) such as GPT4 and Llama2 to
generate plans for self-driving vehicles. In particular, we develop a novel
hybrid planner that leverages a conventional rule-based planner in conjunction
with an LLM-based planner. Guided by commonsense reasoning abilities of LLMs,
our approach navigates complex scenarios which existing planners struggle with,
produces well-reasoned outputs while also remaining grounded through working
alongside the rule-based approach. Through extensive evaluation on the nuPlan
benchmark, we achieve state-of-the-art performance, outperforming all existing
pure learning- and rule-based methods across most metrics. Our code will be
available at https://llmassist.github.io.Comment: 15 pages, 8 figures, 7 table
Density functional investigation of the interaction of acetone with small gold clusters
The structural evolution of Aun (n = 2, 3, 5, 7, 9, and 13) clusters and the adsorption of organic molecules such as acetone, acetaldehyde, and diethyl ketone on these clusters are studied using a density functional method. The detailed study of the adsorption of acetone on the Aun clusters reveals two main points. (1) The acetone molecule interacts with one gold atom of the gold clusters via the carbonyl oxygen. (2) This interaction is mediated through back donation mainly from the spd-hybridized orbitals of the interacting gold atom to the oxygen atom of the acetone molecule. In addition, a hydrogen bond is observed between a hydrogen atom of the methyl group and another gold atom (not involved in the bonding with carbonyl oxygen). Interestingly, the authors notice that the geometries of Au9 and Au13 undergo a significant flattening due to the adsorption of an acetone molecule. They have also investigated the role of the alkyl chain attached to the carbonyl group in the adsorption process by analyzing the interaction of Au13 with acetaldehyde and diethyl ketone
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