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Approximate Birkhoff-James orthogonality in the space of bounded linear operators
No full textThere are two notions of approximate Birkhoff-James orthogonality in a normed space. We characterize both the notions of approximate Birkhoff-James orthogonality in the space of bounded linear operators defined on a normed space. A complete characterization of approximate Birkhoff-James orthogonality in the space of bounded linear operators defined on Hilbert space of any dimension is obtained which improves on the recent result by Chmielinski et al. (2017) 4], in which they characterized approximate Birkhoff-James orthogonality of linear operators on finite dimensional Hilbert space and also of compact operators on any Hilbert space. (C) 2017 Elsevier Inc. All rights reserved
Rising Variability, Not Slowing Down, as a Leading Indicator of a Stochastically Driven Abrupt Transition in a Dryland Ecosystem
No full textComplex systems can undergo abrupt state transitions near critical points. Theory and controlled experimental studies suggest that the approach to critical points can be anticipated by critical slowing down (CSD), that is, a characteristic slowdown in the dynamics. The validity of this indicator in field ecosystems, where stochasticity is important in driving transitions, remains unclear. We analyze long-term data from a dryland ecosystem in the Shapotou region of China and show that the ecosystem underwent an abrupt transition from a nearly bare to a moderate grass cover state. Prior to the transition, the system showed no (or weak) signatures of CSD but exhibited expected increasing trends in the variability of the grass cover, quantified by variance and skewness. These surprising results are consistent with the theoretical expectation of stochastically driven abrupt transitions that occur away from critical points; indeed, a driver of vegetationannual rainfallshowed rising variance prior to the transition. Our study suggests that rising variability can potentially serve as a leading indicator of stochastically driven transitions in real-world ecosystems
Municipal solid waste: Generation, composition and GHG emissions in Bangalore, India
No full textMunicipal solid waste in developing countries mainly consists of degradable materials (> 70%), which plays a significant role in GHG (Greenhouse gas) emissions in urban localities. The increasing municipal solid waste generation along with the high fraction of organic waste and its unscientific disposal is leading to emission of GHG (methane, CO2, etc.) in the atmosphere. Proportion of municipal solid wastes collected by the agencies disposed at identified sites is about 60%, while the balance is disposed-off at unauthorized disposal sites leading to the environmental consequences including greenhouse gas emissions. Mitigation strategy necessitates understanding of composition of waste for its treatment and management in an environmentally sound way. The study revealed that the per capita waste generated is about 91.01 +/- 45.5 g/day with the per capita organic waste generation of 74 +/- 35 g/person/day. The household per capita waste generation was positively related with income and education levels, while negatively related with family (household) size. The organic fractions constitute 82% with the strong recovery potential and conversion to energy or compost range. The total organic waste generated is about 231.01 Gg/year and due to mismanagement consequent emissions are about 604.80 Gg/year. Integrated solid waste management strategy is suggested to manage the organic fractions through technology and policy interventions, which helps in mitigating GHG emissions with potential economic benefits
On Grobner bases and Krull dimension of residue class rings of polynomial rings over integral domains
No full textGiven an ideal a in Ax(1),.... x(n)] where A is a Noetherian integral domain, we propose an approach to compute the Krull dimension of Axi,,.x(n)]/a, when the residue class ring is a free A-module. When A is a field, the Krull dimension of Ax(1),.... x(n)]/a has several equivalent algorithmic definitions by which it can be computed. But this is not true in the case of arbitrary Noetherian rings. For a Noetherian integral domain A we introduce the notion of combinatorial dimension of Ax(1),.... x(n)]/a and give a Grobner basis method to compute it for residue class rings that have a free A-module representation w.r.t. a lexicographic ordering. For such A-algebras, we derive a relation between Krull dimension and combinatorial dimension of Ax(1),.... x(n)]/a. An immediate application of this relation is that it gives a uniform method, the first of its kind, to compute the dimension of Ax(1),.... x(n)]/a without having to consider individual properties of the ideal. For A-algebras that have a free A-module representation w.r.t degree compatible monomial orderings, we introduce the concepts of Hilbert function, Hilbert series and Hilbert polynomials and show that Grobner basis methods can be used to compute these quantities. We then proceed to show that the combinatorial dimension of such A-algebras is equal to the degree of the Hilbert polynomial. This enables us to extend the relation between Krull dimension and combinatorial dimension to A-algebras with a free A-module representation w.r.t. a degree compatible ordering as well. (C) 2017 Elsevier Ltd. All rights reserved
Tuning the Curie temperature of epitaxial Nd0.6Sr0.4MnO3 thin films
No full textNdxSr1-xMnO3 (0.2 <= x <= 0.5) systems are widely studied in magnetism, popular for high colossal magnetoresistance and are ferromagnetic oxides with T-C ranging from 200 K to 300 K. Recently, many of such compounds are re-visited for exploring the correlation of spin, charge and lattice degrees of freedom. Although, manganite thin films are the ideal candidates for studying the electron-correlation effects, the puzzle of obtaining a high quality epitaxial thin films of NdxSr1-xMnO3 are still unsolved contrary to its sister compound LaxSr1-xMnO3. Hence, in this study, we demonstrate the growth of best quality of Nd0.6Sr0.4MnO3 (NSMO) epitaxial thin films. This is evident from the TC and a sharp insulator-tometal transition (IMT) coinciding at as high as similar to 255 K against the bulk T-C (similar to 270 K). It is the highest reported T-C in Nd0.6Sr0.4MnO3 thin films to date. Moreover, as-deposited films with in situ oxygen annealing are not enough to relax the lattice of NSMO films due to the significant Jahn-Teller distortion in the film. With ex situ annealing processes alongside the various deposition and in situ annealing conditions, we have extensively studied the growth of epitaxial NSMO thin films on LaAlO3 (001) and SrTiO3 (001) to investigate the evolution of lattice and its one-to-one correspondence with the magnetism and the electrical properties of thin films. Accordingly, the enhanced magnetization, reduced resistivity and the higher T-C and IMT of the NSMO films obtained from our extensive growth analysis looks promising for the future applications across the T-C and IMT. (C) 2017 Elsevier B.V. All rights reserved
Micromechanical analysis of concrete and reinforcing steel exposed to high temperature
No full textThis study discusses determination of macroscale properties of concrete and reinforcing steel from micromechanical properties (elastic modulus) of individual phases in concrete (coarse aggregate, mortar), and reinforcing steel that have been exposed to high temperature through micro-indentation of their respective samples. Micro-indentation results are obtained by performing grid indentation. These results are then statistically analyzed through a deconvolution technique and a self-consistent homogenization scheme, to obtain the mechanical properties at macroscale. These obtained properties from samples are useful in assessing the nature and extent of damage that has taken place in concrete or steel due to high temperature expressed in terms of stiffness reduction. As a consequence this can provide a basis for designing a suitable structural repair with an understanding of the force flow in the element. Micro indentation of concrete samples in hot state has also been undertaken, and these results suggest that combined thermos-mechanical loads result in more degradation of concrete due to thermo-mechanical coupling. Results of elastic modulus obtained from homogenization of micro-indentation data and the elastic modulus obtained from macroscale tests are in good agreement. (C) 2017 Elsevier Ltd. All rights reserved
The TCP4 transcription factor regulates trichome cell differentiation by directly activating GLABROUS INFLORESCENCE STEMS in Arabidopsis thaliana
No full textTrichomes are the first cell type to be differentiated during the morphogenesis of leaf epidermis and serve as an ideal model to study cellular differentiation. Many genes involved in the patterning and differentiation of trichome cells have been studied over the past decades, and the majority of these genes encode transcription factors that specifically regulate epidermal cell development. However, the upstream regulators of these genes that link early leaf morphogenesis with cell type differentiation are less studied. The TCP proteins are the plant-specific transcription factors involved in regulating diverse aspects of plant development including lateral organ morphogenesis by modulating cell proliferation and differentiation. Here, we show that the miR319-regulated class II TCP proteins, notably TCP4, suppress trichome branching in Arabidopsis leaves and inflorescence stem by direct transcriptional activation of GLABROUS INFLORESCENCE STEMS (GIS), a known negative regulator of trichome branching. The trichome branch number is increased in plants with reduced TCP activity and decreased in the gain-of-function lines of TCP4. Biochemical analyses show that TCP4 binds to the upstream regulatory region of GIS and activates its expression. Detailed genetic analyses show that GIS and TCP4 work in same pathway and GIS function is required for TCP4-mediated regulation of trichome differentiation. Taken together, these results identify a role for the class II TCP genes in trichome differentiation, thus providing a connection between organ morphogenesis and cellular differentiation
Interactive Communication for Data Exchange
No full textTwo parties observing correlated data seek to exchange their data using interactive communication. How many bits must they communicate? We propose a new interactive protocol for data exchange, which increases the communication size in steps until the task is done. We also derive a lower bound on the minimum number of bits that is based on relating the data exchange problem to the secret key agreement problem. Our single-shot analysis applies to all discrete random variables and yields upper and lower bounds of a similar form. In fact, the bounds are asymptotically tight and lead to a characterization of the optimal rate of communication needed for data exchange for a general source sequence, such as a mixture of independent and identically distributed (IID) random variables as well as the optimal second-order asymptotic term in the length of communication needed for data exchange for IID random variables, when the probability of error is fixed. This gives a precise characterization of the asymptotic reduction in the length of optimal communication due to interaction; in particular, two-sided Slepian-Wolf compression is strictly suboptimal
Opsin3-A Link to Visible Light-Induced Skin Pigmentation
No full textSkin pigmentation is primarily dependent on melanogenesis, a physiological process that occurs in melanosomes of melanocytes. Solar radiation modulates pigmentation through variety of signaling pathways, but the mechanism of visible light-induced hyperpigmentation remains uncharacterized. Passeron's group recently reported that visible light stimulates opsin3-regulated calcium-dependent microphthalmia-associated transcription factor activation that increases pigment gene expression and that it also causes the clustering of melanogenic enzymes. Together, these processes possibly contribute to long-lasting hyperpigmentation in the melanocompetent skins
A Versatile Probe for Caffeine Detection in Real-Life Samples via Excitation-Triggered Alteration in the Sensing Behavior of Fluorescent Organic Nanoaggregates
No full textExcitation triggered alteration in the sensing behavior of fluorescent nanoaggregates was explored in water, considering caffeine as the ``target analyte''. Merely by changing the excitation wavelength, we could specifically excite either the monomeric species or the fluorescent nano aggregates. The monomer showed highly sensitive interaction with caffeine despite poor selectivity, while the ``strongly associated'' fluorescent nano aggregates displayed relatively high selectivity with low sensitivity. In addition, the extent of self-aggregation was also found to be influenced by the micropolarity of the local surroundings and the electronics of the core carbazole unit. Furthermore, the present protocol was utilized for the estimation of caffeine in different beverages and biological fluids with reasonably high accuracy. Inexpensive, portable paper strips were designed for a rapid, on-site detection of caffeine without involving sophisticated instruments or trained technicians