Nanoscience and Nano-Technology: Cracking Prodigal Farming

Nano-science coupled with nano-technology has emerged as possible cost-cutting measure to prodigal farming and environmental clean-up operations. It has ushered as a new interdisciplinary field by converging various science disciplines, and is highly relevant to agricultural and food systems. Environmental Protection Agency of USA defined nanotechnology as the understanding and control of matter at dimensions of roughly 1-100 nm, where unique physical properties make novel applications possible. By this definition all soil-clays, many chemicals derived from soil organic matter (SOM), several soil microorganisms fall into this category. Apart from native soil-materials, many new nanotech products are entering into soil system, some of which are used for agricultural production and some others for many other purposes.

Nano-science (also nanotechnology) has found applications in controlling release of nitrogen, characterization of soil minerals, studies of weathering of soil minerals and soil development, micro-morphology of soils, nature of soil rhizosphere, nutrient ion transport in soil-plant system, emission of dusts and aerosols from agricultural soil and their nature, zeoponics, and precision water farming. In its stride, nanotechnology converges soil mineralogy with imaging techniques, artificial intelligence, and encompass bio molecules and polymers with microscopic atoms and molecules, and macroscopic properties (thermodynamics) with microscopic properties (kinetics, wave theory, uncertainty principles, etc.), to name a few. 

Some of the examples include clinoloptolite and other zeolite based substrates, and Fe-, Mn-, and Cu- substituted synthetic hydroxyapatites that have made it possible to grow crops in space stations and at Antarctica. This has eliminated costs of repeated launching of space crafts. A disturbing fact is that the fertilizer use efficiency is 20-50 percent for nitrogen, and 10-25 percent for phosphorus (<1% for rock phosphate in alkaline calcareous soils). With nano-fertilizers emerging as alternatives to conventional fertilizers, build ups of nutrients in soils and thereby eutrophication and drinking water contamination may be eliminated. In fact, nano-technology has opened up new opportunities to improve nutrient use efficiency and minimize costs of environmental protection. It has helped to divulge to recent findings that plant roots and microorganisms can directly lift nutrient ions from solid phase of minerals (that includes so-called susceptible (i.e., easily weatherable, as well as non-susceptible minerals)

Privacy-Preserving Population-Enhanced Biometric Key Generation from Free-Text Keystroke Dynamics

Biometric key generation techniques are used to reliably generate cryptographic material from biometric signals. Existing constructions require users to perform a particular activity (e.g., type or say a password, or provide a handwritten signature), and are therefore not suitable for generating keys continuously. In this paper we present a new technique for biometric key generation from free-text keystroke dynamics. This is the first technique suitable for continuous key generation. Our approach is based on a scaled parity code for key generation (and subsequent key reconstruction), and can be augmented with the use of population data to improve security and reduce key reconstruction error. In particular, we rely on linear discriminant analysis (LDA) to obtain a better representation of discriminable biometric signals. To update the LDA matrix without disclosing user's biometric information, we design a provably secure privacy-preserving protocol (PP-LDA) based on homomorphic encryption. Our biometric key generation with PP-LDA was evaluated on a dataset of 486 users. We report equal error rate around 5% when using LDA, and below 7% without LDA

Anisotropic Topological Hall Effect with Real and Momentum Space Berry Curvature in the Antiskrymion Hosting Heusler Compound Mn1.4_{1.4}PtSn

The topological Hall effect (THE) is one of the key signatures of topologically non-trivial magnetic spin textures, wherein electrons feel an additional transverse voltage to the applied current. The magnitude of THE is often small compared to the anomalous Hall effect. Here, we find a large THE of 0.9 $\mu\Omega$cm that is of the same order of the anomalous Hall effect in the single crystalline antiskyrmion hosting Heusler compound Mn$_{1.4}$PtSn, a non-centrosymmetric tetragonal compound. The THE is highly anisotropic and survives in the whole temperature range where the spin structure is noncoplanar (<170 K). The THE is zero above the spin reorientation transition temperature of 170 K, where the magnetization will have a collinear and ferromagnetic alignment. The large value of the THE entails a significant contribution from the momentum space Berry curvature along with real space Berry curvature, which has never been observed earlier

Hydrodynamics of quantum spin liquids

Quantum spin liquids are topological states of matter that arise in frustrated quantum magnets at low temperatures. At low energies, such states exhibit emergent gauge fields and fractionalized quasiparticles and can also possess enhanced global symmetries compared to their parent microscopic Hamiltonians. We study the consequences of this emergent gauge and symmetry structure for the hydrodynamics of quantum spin liquids. Specifically, we analyze two cases, the $U(1)$ spin liquid with a Fermi surface and the $SU(4)$-symmetric "algebraic" spin liquid. We show that the emergent degrees of freedom in the spin liquid phase lead to a variety of additional hydrodynamic modes compared to the high-temperature paramagnetic phase. We identify a hydrodynamic regime for the internal $U(1)$ gauge field common to both states, characterized by slow diffusion of the internal transverse photon.Comment: v2: 11+4 pages, 1 figure, accepted versio

Quantifying Planarian Behavior As An Introduction To Object Tracking And Signal Processing

Answers to mechanistic questions about biological phenomena require fluency in a variety of molecular biology techniques and physical concepts. Here, we present an interdisciplinary approach to introducing undergraduate students to an important problem in the areas of animal behavior and neuroscience—the neuronal control of animal behavior. In this lab module, students explore planarian behavior by quantitative image and data analysis with freely available software and low-cost resources. Planarians are ∼1–2-cm-long aquatic free-living flatworms famous for their regeneration abilities. They are inexpensive and easy to maintain, handle, and perturb, and their fairly large size allows for image acquisition with a webcam, which makes this lab module accessible and scalable. Our lab module integrates basic physical concepts such as center of mass, velocity and speed, periodic signals, and time series analysis in the context of a biological system. The module is designed to attract students with diverse disciplinary backgrounds. It challenges the students to form hypotheses about behavior and equips them with a basic but broadly applicable toolkit to achieve this quantitatively. We give a detailed description of the necessary resources and show how to implement the module. We also provide suggestions for advanced exercises and possible extensions. Finally, we provide student feedback from a pilot implementation