Prioritizing Safety Climate Improvements in the Indonesian Construction Industry Using Supervised Classification

Despite its significance, the Indonesian construction industry has poor safety performance. Improving the safety climate has been seen as a way to improve safety in the industry. Research on safety climate in this context has identified a range of safety climate factors that require improvements. However, construction organizations face difficulties in implementing improvement recommendations due to resource constraints. In order to help construction organizations in their efforts to improve the safety climate, this research demonstrates the use of supervised classification approaches to identify specific safety climate factors that construction organizations should focus on. Data were collected from 311 construction practitioners in Indonesia using a 22-item safety climate survey. Supervised classification methods, comprising ensemble methods, Support Vector Machine, Naive Bayes, and Nearest Neighbor, were used. The analysis identified 14 safety climate items that can represent the original dataset with high accuracy (93%). These 14 items can be considered crucial items that should be prioritized in the Indonesian construction industry. These items revealed that, due to the high power distance culture in Indonesia, top-down approaches, such as giving clear instructions, providing training, and reminding people often about safety, are effective for engaging employees to focus on and participate in safety. The findings also suggest that understanding cultural context is important to determine effective strategies to improve safety. This research has also demonstrated the potential application of supervised classification approaches to help decision makers improve safety by focusing on crucial factors within a context

SENTINEL PLANTS TO IMPROVE NUTRIENT USE EFFICIENCY: LIVING TOOLS FOR NONDESTRUCTIVE ANALYSIS UNDER FIELD CONDITIONS

Sulfur is an essential element for plant growth which availability affects both quantitative and qualitative traits of crop yield. Our aim was to generate specific bioassays based on the use of \u201csentinel plants\u201d to quickly determine sulfate bioavailability and/or crop nutritional status which may represent a reliable and efficient strategy to obtain valuable, timely and low-cost information about changes in sulfate availabilities and nutritional requirements in a crop system. The characterization of two Arabidopsis gene-trap lines (FLAG and 718 lines) allowed the identification of two portions (440 and 1331-bp respectively) of the intergenic region (between At1g12030 and At1g12040), controlling as a bidirectional promoter the expression of both At1g12030 and GUS under sulfur limitation. Thus, these lines are able to provide information about the sulfur nutritional status of the plant and/or the sulfate concentration in the growing medium. For this purpose, the two lines were grown in agar plates under a continuous sulfate gradient ranging from 0 to 150 \u3bcM in order to describe the growth of both roots and shoots as a function of sulfate external concentration and to determine the critical concentration of sulfate (i.e. the minimum concentration of sulfate necessary to achieve maximum biomass) in the growing medium. The main results indicate that the pilot lines are able to correctly indicate the critical concentration of sulfate in the external medium also in the presence of interfering metal ions (such as cadmium) able to increase the plant metabolic demand for sulfur. Others experiments were done to better characterize the pilot bioindicators. Firstly, experiments were conducted in order to evaluate if the lines sense the lack of sulfate in the growth medium or indicates an alteration of the S nutritional status in the plant. For this purpose the response of the lines was analyzed growing the plants in the presence of cysteine or glutathione as sole sulfur source. The presence of cysteine as sole sulfur source in the agar medium did not produce any GUS activity in both shoots and roots, differently from glutathione which instead induced GUS activity only in the shoots. The results indicate that the promoters of the Arabidopsis pilot bioindicators sense the metabolic effect produced by sulfur starvation and not the presence/absence of sulfate in the growing medium. Moreover, GUS expression was studied in lines grown in hydroponic media containing different sulfate concentrations. Interestingly, both lines showed GUS expression when grown in agar media in sulfur starved conditions, whereas in hydroponics, a significant GUS expression was detectable only in the FLAG line, for sulfate concentrations 64 5 \u3bcM. To better analyze this effect we tested the effect of sucrose, only present in agar media, on GUS expression and results show that expression level of GUS is influenced not only by sulfur but also by the presence of sucrose in the external medium. Finally, we tested the bidirectional promoter- 2 3 function of the 440-bp intergenic region shared by the divergent genes At1g12030 and GUS using GUS reporter gene in both orientations in stably transformed transgenic Arabidopsis. The sulfur responsive functional nature of the bidirectional promoter was evaluated in independent transgenic Arabidopsis lines. The 440-bp bidirectional promoter in both orientations shows GUS expression under sulfur limitation which was detected in the leaves and the root tissues indicating that 440-bp fragment is able to modulate the expression of GUS in two orientations under sulfur starvation. Then, to confirm the response of 440-bp promoters to sense the metabolic effect produced by sulfur starvation, transgenic Arabidopsis plants were grown in complete agar medium in the presence of cadmium. Results of this experiment showed that also Cd was able to induce a strong GUS activity in both leaves (vascular tissues) and root tips. In conclusion, we identified putative bidirectional promoters involved in modulating the expression of GUS reporter gene in response to sulfur deficient conditions and suitable for developing specific bioindicators to monitor plant S nutritional status

Implications of the Babinet Principle for Casimir Interactions

We formulate the Babinet Principle (BP) as a relation between the scattering amplitudes for electromagnetic waves, and combine it with multiple scattering techniques to derive new properties of Casimir forces. We show that the Casimir force exerted by a planar conductor or dielectric on a self- complementary perforated planar mirror is approximately half that on a uniform mirror independent of the distance between them. The BP suggests that Casimir edge effects are anomalously small, supporting results obtained earlier in special cases. Finally, we illustrate how the BP can be used to estimate Casimir forces between perforated planar mirrors

Casimir force between sharp-shaped conductors

Casimir forces between conductors at the sub-micron scale cannot be ignored in the design and operation of micro-electromechanical (MEM) devices. However, these forces depend non-trivially on geometry, and existing formulae and approximations cannot deal with realistic micro-machinery components with sharp edges and tips. Here, we employ a novel approach to electromagnetic scattering, appropriate to perfect conductors with sharp edges and tips, specifically to wedges and cones. The interaction of these objects with a metal plate (and among themselves) is then computed systematically by a multiple-scattering series. For the wedge, we obtain analytical expressions for the interaction with a plate, as functions of opening angle and tilt, which should provide a particularly useful tool for the design of MEMs. Our result for the Casimir interactions between conducting cones and plates applies directly to the force on the tip of a scanning tunneling probe; the unexpectedly large temperature dependence of the force in these configurations should attract immediate experimental interest

Spontaneous emission by rotating objects: A scattering approach

We study the quantum electrodynamics (QED) vacuum in the presence of a body rotating along its axis of symmetry and show that the object spontaneously emits energy if it is lossy. The radiated power is expressed as a general trace formula solely in terms of the scattering matrix, making an explicit connection to the conjecture of Zel'dovich [JETP Lett. 14, 180 (1971)] on rotating objects. We further show that a rotating body drags along nearby objects while making them spin parallel to its own rotation axis

Fluctuation-induced phenomena in non-equilibrium systems

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 2013.Cataloged from PDF version of thesis.Includes bibliographical references (pages 128-134).In this thesis, we investigate the implications of fluctuations in systems away, possibly even far, from equilibrium due to their motion either in or out of thermal equilibrium. This subject encompasses several topics in physics including the dynamical Casimir effect in the presence of moving boundaries, and non-contact friction between objects in relative motion. In both cases, photons are created due to the coupling of the motion and zero-point fluctuations in the vacuum, resulting in dissipation and radiative loss. We introduce a general formalism, equally applicable to lossy and ideal objects, to compute the quantum radiation and dissipation effects solely in terms of the classical scattering matrices. We obtain trace formulas which are general and independent of any approximation scheme where numerous examples, many novel, are discussed in great detail. Specifically, we give an exact treatment of quantum fluctuations in the context of a neutral rotating object, and show that it spontaneously emits photons and drags objects nearby, and compute the associated photon statistics and entropy generation. In the context of non-contact friction, we find a quantum analog of the classical Cherenkov effect for two neutral plates in relative motion, purely due to quantum fluctuations. We present a number of arguments and exact proofs, including a method introduced in the context of quantum field theory in curved space, as well as the scattering approach, to show that a friction force between two plates appears at a threshold velocity set by the speed of light in their medium.by Mohammad F. Maghrebi.Ph.D

A diagrammatic expansion of the Casimir energy in multiple reflections: theory and applications

We develop a diagrammatic representation of the Casimir energy of a multibody configuration. The diagrams represent multiple reflections between the objects and can be organized by a few simple rules. The lowest-order diagrams (or reflections) give the main contribution to the Casimir interaction which proves the usefulness of this expansion. Among some applications of this, we find analytical formulae describing the interaction between "edges", i.e. semi-infinite plates, where we also give a first example of blocking in the context of the Casimir energy. We also find the interaction of edges with a needle and describe analytically a recent model of the repulsion due to the Casimir interaction