99 research outputs found
High resolution imaging of IgG and IgM molecules by scanning tunneling microscopy in air condition
A scanning tunneling microscope is a powerful tool for obtaining micrographs from conductive and semiconductive materials. The imaging technique has recently been improved for microscopy of nanostructured biomaterials on highly ordered atomic surfaces. We describe, here, high resolution imaging of individual IgM and IgG using a scanning tunneling microscope (Nama-STM) in air condition. The biomolecules were immobilized on the surface of Highly Ordered Pyrolytic Graphite (HOPG). Obtained micrographs could reveal structural details of immunoglobulins G and M on the atomically flat surfaces. Obtained results confirmed that STM could be more useful than other microscopy techniques for the analysis of single biomolecules. © 2012 Sharif University of Technology. Production and hosting by Elsevier B.V. All rights reserved
Estimating flood characteristics using geomorphologic flood index with regards to rainfall intensity-duration-frequency-area curves and CADDIES-2D model in three Iranian basins
This is the final version. Available on open access from MDPI via the DOI in this recordThere is not enough data and computational power for conventional flood mapping methods in many parts of the world, thus fast and low-data-demanding methods are very useful in facing the disaster. This paper presents an innovative procedure for estimating flood extent and depth using only DEM SRTM 30 m and the Geomorphic Flood Index (GFI). The Geomorphologic Flood Assessment (GFA) tool which is the corresponding application of the GFI in QGIS is implemented to achieved the results in three basins in Iran. Moreover, the novel concept of Intensity-Duration-Frequency-Area (IDFA) curves is introduced to modify the GFI model by imposing a constraint on the maximum hydrologically contributing area of a basin. The GFA model implements the linear binary classification algorithm to classify a watershed into flooded and non-flooded areas using an optimized GFI threshold that minimizes the errors with a standard flood map of a small region in the study area. The standard hydraulic model envisaged for this study is the Cellular Automata Dual-DraInagE Simulation (CADDIES) 2D model which employs simple transition rules and a weight-based system rather than complex shallow water equations allowing fast flood modelling for large-scale problems. The results revealed that the floodplains generated by the GFI has a good agreement with the standard maps, especially in the fluvial rivers. However, the performance of the GFI decreases in the less steep and alluvial rivers. With some overestimation, the GFI model is also able to capture the general trend of water depth variations in comparison with the CADDIES-2D flood depth map. The modifications made in the GFI model, to confine the maximum precipitable area through implementing the IDFAs, improved the classification of flooded area and estimation of water depth in all study areas. Finally, the calibrated GFI thresholds were used to achieve the complete 100-year floodplain maps of the study areas.University of BasilicataCNR-IMAAOpenet TechnologiesRoyal Academy of Engineering (RAE
Estimation of soil moisture from UAS platforms using RGB and thermal imaging sensors in arid and semi-arid regions
Soil moisture (SM) is a connective hydrological variable between the Earth’s surface and atmosphere and affects various climatological processes. Surface soil moisture (SSM) is a key component for addressing energy and water exchanges and can be estimated using different techniques, such as in situ and remote sensing (RS) measurements. Discrete, costly and prolonged, in situ measurements are rarely capable in demonstration of moisture fluctuations. On the other hand, current high spatial resolution satellite sensors lack the spectral resolution required for many quantitative RS applications, which is critical for heterogeneous covers. RS-based unmanned aerial systems (UASs) represent an option to fill the gap between these techniques, providing low-cost approaches to meet the critical requirements of spatial, spectral and temporal resolutions. In the present study, SM was estimated through a UAS equipped with a thermal imaging sensor. To this aim, in October 2018, two airborne campaigns during day and night were carried out with the thermal sensor for the estimation of the apparent thermal inertia (ATI) over an agricultural field in Iran. Simultaneously, SM measurements were obtained in 40 sample points in the different parts of the study area. Results showed a good correlation (R2=0.81) between the estimated and observed SM in the field. This study demonstrates the potential of UASs in providing high-resolution thermal imagery with the aim to monitor SM over bare and scarcely vegetated soils. A case study based in a wide agricultural field in Iran was considered, where SM monitoring is even more critical due to the arid and semi-arid climate, the lack of adequate SM measuring stations, and the poor quality of the available data
A Nonabelian Yang-Mills Analogue of Classical Electromagnetic Duality
The classic question of a nonabelian Yang-Mills analogue to electromagnetic
duality is here examined in a minimalist fashion at the strictly 4-dimensional,
classical field and point charge level. A generalisation of the abelian Hodge
star duality is found which, though not yet known to give dual symmetry,
reproduces analogues to many dual properties of the abelian theory. For
example, there is a dual potential, but it is a 2-indexed tensor
of the Freedman-Townsend type. Though not itself functioning as such,
gives rise to a dual parallel transport, , for the
phase of the wave function of the colour magnetic charge, this last being a
monopole of the Yang-Mills field but a source of the dual field. The standard
colour (electric) charge itself is found to be a monopole of .
At the same time, the gauge symmetry is found doubled from say to
. A novel feature is that all equations of motion,
including the standard Yang-Mills and Wong equations, are here derived from a
`universal' principle, namely the Wu-Yang (1976) criterion for monopoles, where
interactions arise purely as a consequence of the topological definition of the
monopole charge. The technique used is the loop space formulation of Polyakov
(1980).Comment: We regret that, due to a technical hitch, parts of the reference list
were mixed up. This is the corrected version. We apologize to the authors
whose papers were misquote
Leptogenesis in Theories with Large Extra Dimensions
We study the scenario of baryogenesis through leptogenesis in
higher-dimensional theories, in which the scale of quantum gravity is many
orders of magnitude smaller than the usual Planck mass. The minimal realization
of these theories includes an isosinglet neutrino which feels the presence of
large compact dimensions, whereas all the SM particles are localized on a
-dimensional subspace. In the formulation of minimal leptogenesis
models, we pay particular attention to the existence of Majorana spinors in
higher dimensions. After compactification of the extra dimensions, we obtain a
tower of Majorana Kaluza-Klein excitations which act as an infinite series of
CP-violating resonators, and derive the necessary conditions for their
constructive interference. Based on this CP-violating mechanism, we find that
the decays of the heavy Majorana excitations can produce a leptonic asymmetry
which is reprocessed into the observed baryonic asymmetry of the Universe by
means of out-of-equilibrium sphaleron interactions, provided the reheat
temperature is above 5 GeV.Comment: 34 pages, minor rewordings, to appear in Physical Review
Models of Neutrino Masses and Baryogenesis
Majorana masses of the neutrino implies lepton number violation and is
intimately related to the lepton asymmetry of the universe, which gets related
to the baryon asymmetry of the universe in the presence of the sphalerons
during the electroweak phase transition. Assuming that the baryon asymmetry of
the universe is generated before the electroweak phase transition, it is
possible to dicriminate different classes of models of neutrino masses. While
see-saw mechanism and the triplet higgs mechanism are preferred, the Zee-type
radiative models and the R-parity breaking models requires additional inputs to
generate baryon asymmetry of the universe during the electroweak phase
transition.Comment: 27 pages including 5 figures; Review article for Pramana: the Indian
Journal of Physic
Thermal leptogenesis in a model with mass varying neutrinos
In this paper we consider the possibility of neutrino mass varying during the
evolution of the Universe and study its implications on leptogenesis.
Specifically, we take the minimal seesaw model of neutrino masses and introduce
a coupling between the right-handed neutrinos and the dark energy scalar field,
the Quintessence. In our model, the right-handed neutrino masses change as the
Quintessence scalar evolves. We then examine in detail the parameter space of
this model allowed by the observed baryon number asymmetry. Our results show
that it is possible to lower the reheating temperature in this scenario in
comparison with the case that the neutrino masses are unchanged, which helps
solve the gravitino problem. Furthermore, a degenerate neutrino mass patten
with larger than the upper limit given in the minimal leptogenesis
scenario is permitted.Comment: 18 pages, 7 figures, version to appear in PR
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