Plasma photoemission from string theory

Leading 't Hooft coupling corrections to the photoemission rate of the planar limit of a strongly-coupled {\cal {N}}=4 SYM plasma are investigated using the gauge/string duality. We consider the full order \alpha'^3 type IIB string theory corrections to the supergravity action, including higher order terms with the Ramond-Ramond five-form field strength. We extend our previous results presented in arXiv:1110.0526. Photoemission rates depend on the 't Hooft coupling, and their curves suggest an interpolating behaviour from strong towards weak coupling regimes. Their slopes at zero light-like momentum give the electrical conductivity as a function of the 't Hooft coupling, in full agreement with our previous results of arXiv:1108.6306. Furthermore, we also study the effect of corrections beyond the large N limit.Comment: 36 pages, 5 figures, paragraph added in the conclusions, references added, typos correcte

Four-point functions and kaon decays in a minimal AdS/QCD model

We study the predictions of holographic QCD for various observable four-point quark flavour current-current correlators. The dual 5-dimensional bulk theory we consider is a $SU(3)_L \times SU(3)_R$ Yang Mills theory in a slice of $AdS_5$ spacetime with boundaries. Particular UV and IR boundary conditions encode the spontaneous breaking of the dual 4D global chiral symmetry down to the $SU(3)_V$ subgroup. We explain in detail how to calculate the 4D four-point quark flavour current-current correlators using the 5D holographic theory, including interactions. We use these results to investigate predictions of holographic QCD for the $\Delta I = 1/2$ rule for kaon decays and the $B_K$ parameter. The results agree well in comparison with experimental data, with an accuracy of 25% or better. The holographic theory automatically includes the contributions of the meson resonances to the four-point correlators. The correlators agree well in the low-momentum and high-momentum limit, in comparison with chiral perturbation theory and perturbative QCD results, respectively.Comment: Published version, title changed to conform with Journal format, references and clarifying remarks added, 40 pages, 5 figure

Assessment of the challenges influencing the adoption of smart building technologies

Introduction: Over the past few decades, there has been an increasing focus on Smart Building Projects (SBP) and the technologies associated with them. Numerous studies have been conducted globally to define smart building technologies (SBT), identify challenges, and explore areas for improvement. This study aims to examine the concept and terminology of SBT and the expertise and experience of participants in SBP in the Arab Gulf countries, specifically Saudi Arabia. The study also investigates the challenges faced by SBT throughout its life cycle.Methods: To identify and assess the challenges affecting the adoption of smart building technologies. This approach included a literature review, pilot-testing, and a questionnaire survey. The survey targeted a sample of 90 architects/engineers, managers, and contractors.Results: A total of 55 challenges were identified and categorized into four groups, corresponding to the key phases of the project life cycle. These phases include the programming and feasibility analysis phase, design phase, installation and commissioning phase, and operation and maintenance phase. The findings of this research expand the body of knowledge by providing architects/engineers, managers, and contractors in the architecture, engineering, construction, and facility management (AEC/FM) industry with insights into the influential challenges related to the adoption of SBT. In conclusion, this study sheds light on the concept and terminology of smart building technologies and explores the challenges faced by SBT during its life cycle. By identifying and categorizing these challenges, the study provides valuable information to AEC/FM practitioners, enabling them to overcome obstacles and improve the adoption of SBT

On the possibility of light string resonances at the LHC and Tevatron from Randall-Sundrum throats

In string realizations of the Randall-Sundrum scenario, the higher-spin Regge excitations of Standard Model states localized near the IR brane are warped down to close to the TeV scale. We argue that, as a consequence of the localization properties of Randall-Sundrum models of flavour, the lightest such resonance is the spin-3/2 excitation of the right-handed top quark over a significant region of parameter space. A mild accidental cancellation allows this resonance to be as light or lighter than the Kaluza-Klein excitations of the Standard Model states. We consider from a bottom-up effective theory point of view the production and possible observability of such a spin-3/2 excitation at the LHC and Tevatron. Current limits are weaker than might be expected because of the excess of WWjj events at the Tevatron reported by CDF for an invariant mass of 400-500 GeV.Comment: 17 pages, 6 figures Version published in JHEP with minor correction

Sequestered Dark Matter

We show that hidden-sector dark matter is a generic feature of the type IIB string theory landscape and that its lifetime may allow for a discovery through the observation of very energetic gamma-rays produced in the decay. Throats or, equivalently, conformally sequestered hidden sectors are common in flux compactifications and the energy deposited in these sectors can be calculated if the reheating temperature of the standard model sector is known. Assuming that throats with various warp factors are available in the compact manifold, we determine which throats maximize the late-time abundance of sequestered dark matter. For such throats, this abundance agrees with cosmological data if the standard model reheating temperature was 10^10 - 10^11 GeV. In two distinct scenarios, the mass of dark matter particles, i.e. the IR scale of the throat, is either around 10^5 GeV or around 10^10 GeV. The lifetime and the decay channels of our dark matter candidates depend crucially on the fact that the Klebanov-Strassler throat is supersymmetric. Furthermore, the details of supersymmetry breaking both in the throat and in the visible sector play an essential role. We identify a number of scenarios where this type of dark matter can be discovered via gamma-ray observations.Comment: 36 pages, 3 figures; v2: references added, v3: introduction extended and typos correcte

Biochemical Responses of Date Palm Phoenix dactylifera L. to Combined Stress of Salinity and Nickel

This study examined the effects of nickel (Ni) at 0, 25, and 50 mg.L-1 concentrations, applied alone or in combination with salinity (represented by NaCl at 0, 100, and 200 mM concentrations), on the biochemical traits of date palm. Hydrogen peroxide (H2O2), malondialdehyde (MDA), membrane stability index (MSI), peroxidase (POD) activity, superoxide dismutase (SOD), and proline content were among the parameters evaluated. The results revealed significant effects of nickel and salinity on the studied biochemical markers. Nickel at 50 mg.L-1 significantly increased H2O2 (0.87 µmol. L-1) and MDA (2.46 nmol.g-1) levels, while decreasing MSI (75.85%). Moreover, it enhanced POD (25.09 U.min-1.g-1) and SOD (3.78 U. min-1.g-1) activity, as well as proline content (4.35 µmol.g-1). Salinity at 200 mM significantly increased H2O2 (0.90 µmol L-1) and MDA (2.54 nmol.g-1) levels, decreased MSI (77.69%), and increased POD (27.61 U. min-1.g-1) and SOD (3.77 U.min-1.g-1) activity, along with increased proline content (4.54 µmol.g-1). Additionally, the combined application of nickel and salinity, particularly at higher concentrations, resulted in significantly increased biochemical responses compared to individual treatments. The findings highlight the interactive effects of nickel and salinity on the oxidative and antioxidant mechanisms in date palm plants. This study contributes to our understanding of plant responses to abiotic stressors and provides insights for optimizing date palm cultivation under challenging environmental conditions

On higher derivative gravity, c-theorems and cosmology

We consider higher derivative gravity lagrangians in 3 and 4 dimensions, which admit simple c-theorems, including upto six derivative curvature invariants. Following a suggestion by Myers, these lagrangians are restricted such that the fluctuations around (anti) de Sitter spaces have second order linearized equations of motion. We study c-theorems both in the context of AdS/CFT and cosmology. In the context of cosmology, the monotonic function is the entropy defined on the apparent horizon through Wald's formula. Exact black hole solutions which are asymptotically (anti) de Sitter are presented. An interesting lower bound for entropy is found in de Sitter space. Some aspects of cosmology in both D=3 and D=4 are discussed.Comment: 23 pages, v3: clarifications added, references adde

Évaluation de la productivité de la pomme de terre (Solanum Tuberosum L.), sous l'effet de l'irrigation avec une eau traitée magnétiquement dans la région de Chaouia (Maroc)

The literature reports that there are some beneficial effects of irrigation water treatment by a static magnetic field. Magnetic field improved the production and the growth characteristics of the plants and make water less limiting to production conditions. To quantify the effect of the application of this new technology on crop production in Moroccan production conditions, an experiment was conducted in situ on a farm situated in the region of Chaouia-Ouardigha. A randomized complete design, with three replicates, was used in the experiment for each treatment of irrigation water (magnetized and ordinary). Potatoes plants (Solanum tuberosum L.),were controlled through regular measurements of growth and production parameters. Magnetic treatments of irrigation water gave the best results. We noted a significantly increase in plant height; branch number; fresh weight of aerial part; dry matter and root fresh weight in the order of 13,9%; 50%; 110%; 91,6% and 40,1%, respectively and an increase in the yield of 35,7%. Finally, we emphasized that the technique of magnetic field in agricultural fields could be a promising technique for agricultural production improvement but extensive research is still required. Key words: Magnetic technology, irrigation water, magnetic field, potatoLes rapports de la littérature révèlent que le traitement physique de l’eau par un champ magnétique statique montre des effets bénéfiques sur la productivité de l’eau ainsi que sur les paramètres de croissance des plantes, rendant ainsi l’eau un facteur moins limitant pour la production. En vue de quantifier l’effet de l’application de cette nouvelle technologie sur la production végétale dans les conditions de production marocaines, une expérimentation a été conduite au champ dans la région de Chaouia-Ouardigha. Le dispositif expérimental est complètement aléatoire avec 3 répétitions pour chaque traitement de l’eau d’irrigation (magnétique et normale). Les plantes de pomme de terre (Solanum tuberosum L.) étaient suivies à travers les mesures des paramètres de croissance végétale et de production. Les meilleurs résultats sont enregistrés pour le traitement magnétique de l’eau d’irrigation, à savoir: une augmentation hautement significative de la hauteur; le nombre de branches principales; la masse aérienne; la matière sèche et la masse racinaire, de l’ordre de 13,9%; 50%; 110%; 91,6% et 40,1%, respectivement et une augmentation du rendement de 35,7%. Finalement, L’utilisation du traitement magnétique de l’eau dans le domaine agricole peut être une technique prometteuse, dont la connaissance demande à être approfondie. Mots clés: Technologie magnétique, eau d’irrigation, champ magnétique, pomme de terre &nbsp