Greenhouse engineering: New technologies and approaches

Firstly, this article discusses the greenhouse engineering situation in three geographic areas which are relevant in the field of protected cultivation: Northern Asia, The Netherlands and the Mediterranean. For each area, the prevailing greenhouse type and equipment is briefly described. Secondly, the main technological constraints are pointed out and finally the research directions are discussed. For all areas under consideration, attempts to design more efficient greenhouse systems are under way. In Northern Asia progress is being made towards the optimisation of greenhouses as a solar collector and to the development of new heating strategies. Important subjects addressed in The Netherlands are energy conservation and the replacement or alleviation of human labour by increasing mechanisation. In the Mediterranean there is growing interest in semi-closed greenhouses with CO2 enrichment and control of excessive humidity. All geographic areas share the need of having an optimised climate control based on the crop response to the greenhouse environment. All areas also share the requirement of being respectful to the environment, therefore future greenhouses are expected to use engineering to produce with minimal or zero emissions

Practical use of reactor anti-neutrinos for nuclear safeguard in Vietnam

One of the most abundant man-made sources of low energy (few~MeVs) neutrinos, reactor neutrino, is not only useful for studying neutrino properties, but it is also used in practical applications. In this study, we investigate the practical use of reactor neutrino detectors for nuclear safeguard in Vietnam, specifically at the Dalat Nuclear Reactor, a future research facility, and presumably commercial reactors with 500~kW, 10~MW, and 1000~MW thermal powers, respectively. We compute the rate of observed inverted beta decay events, as well as the statistical significance of extracting isotope composition under the practical assumptions of detector mass, detection efficiency, and background level. We find that a 1-ton detector mass can allow us to detect the reactor's on-off transition state from a few hours to a few days, depending on the standoff distance and reactor thermal power. We investigate how background and energy resolution affect the precision of the extracted weapon-usable ${}^{239}\text{Pu}$ isotope. We conclude that in order to distinguish the 10\% variation of the ${}^{239}\text{Pu}$ in the 10~MW thermal power reactor, a 1-ton detector placed 50~m away must achieve 1\% background level. Increasing the statistics by using a 10x larger detector or placing it $\sqrt{10}$ times closer to the reactor alleviates the requirement of the background level to 10\%

Compensation in Verbal and Nonverbal Communication after Total Laryngectomy

Total laryngectomy is a major surgical procedure with life-changing consequences. As a result of the surgery, the upper and lower airways are disconnected, the natural voice is lost, and patients breathe through a tracheostoma in the neck. Tracheoesophageal speech is the most common speech rehabilitation technique. Due to the lack of air volume, and the amount of muscle tension in the esophagus, some patients may suffer from a hyper- or hypo-tonic voice, resulting in less intelligible speech. To communicate as intelligibly as possible, patients likely adapt their verbal and nonverbal communication to their physical disabilities. The current study aimed to explore the compensation techniques in verbal and nonverbal communication after total laryngectomy focusing on the complexity of grammar and the use of co-speech gestures. We analyzed previously obtained interviews of eight laryngectomized women on the syntactic complexity in speech and the use and type of co-speech gestures. Results were compared with analyses of productions by healthy controls. We found that laryngectomized women reduce the syntactic complexity of their speech, and use nonverbal gestures in their communication. Further research is needed with systematically obtained data and more suitable match-groups

Hall viscosity from gauge/gravity duality

In (2+1)-dimensional systems with broken parity, there exists yet another transport coefficient, appearing at the same order as the shear viscosity in the hydrodynamic derivative expansion. In condensed matter physics, it is referred to as "Hall viscosity". We consider a simple holographic realization of a (2+1)-dimensional isotropic fluid with broken spatial parity. Using techniques of fluid/gravity correspondence, we uncover that the holographic fluid possesses a nonzero Hall viscosity, whose value only depends on the near-horizon region of the background. We also write down a Kubo's formula for the Hall viscosity. We confirm our results by directly computing the Hall viscosity using the formula.Comment: 12 page

Spin Currents Induced by Nonuniform Rashba-Type Spin-Orbit Field

We study the spin relaxation torque in nonmagnetic or ferromagnetic metals with nonuniform spin-orbit coupling within the Keldysh Green's function formalism. In non-magnet, the relaxation torque is shown to arise when the spin-orbit coupling is not uniform. In the absence of an external field, the spin current induced by the relaxation torque is proportional to the vector chirality of Rashba-type spin-orbit field (RSOF). In the presence of an external field, on the other hand, spin relaxation torque arises from the coupling of the external field and vector chirality of RSOF. Our result indicates that spin-sink or source effects are controlled by designing RSOF in junctions.Comment: 3 figure

Identification and tunable optical coherent control of transition-metal spins in silicon carbide

Color centers in wide-bandgap semiconductors are attractive systems for quantum technologies since they can combine long-coherent electronic spin and bright optical properties. Several suitable centers have been identified, most famously the nitrogen-vacancy defect in diamond. However, integration in communication technology is hindered by the fact that their optical transitions lie outside telecom wavelength bands. Several transition-metal impurities in silicon carbide do emit at and near telecom wavelengths, but knowledge about their spin and optical properties is incomplete. We present all-optical identification and coherent control of molybdenum-impurity spins in silicon carbide with transitions at near-infrared wavelengths. Our results identify spin $S=1/2$ for both the electronic ground and excited state, with highly anisotropic spin properties that we apply for implementing optical control of ground-state spin coherence. Our results show optical lifetimes of $\sim$60 ns and inhomogeneous spin dephasing times of $\sim$0.3 $\mu$s, establishing relevance for quantum spin-photon interfacing.Comment: Updated version with minor correction, full Supplementary Information include

Nonlinear Hydrodynamics from Flow of Retarded Green's Function

We study the radial flow of retarded Green's function of energy-momentum tensor and $R$-current of dual gauge theory in presence of generic higher derivative terms in bulk Lagrangian. These are first order non-linear Riccati equations. We solve these flow equations analytically and obtain second order transport coefficients of boundary plasma. This way of computing transport coefficients has an advantage over usual Kubo approach. The non-linear equation turns out to be a linear first order equation when we study the Green's function perturbatively in momentum. We consider several examples including $Weyl^4$ term and generic four derivative terms in bulk. We also study the flow equations for $R$-charged black holes and obtain exact expressions for second order transport coefficients for dual plasma in presence of arbitrary chemical potentials. Finally we obtain higher derivative corrections to second order transport coefficients of boundary theory dual to five dimensional gauge supergravity.Comment: Version 2, reference added, typos correcte