In situ ac Stark shift detection in light storage spectroscopy

We report on a method for measuring ac Stark shifts observed in stored light experiments while simultaneously determining the energetic splitting between the electronic ground states involved in the two-photon transition. To this end, we make use of the frequency matching effect in light storage spectroscopy. We find a linear dependence on the intensity of the control field applied during the retrieval phase of the experiment. At the same time, we observe that the light shift is insensitive to the intensity of the signal field which is in contrast to continuously operated electromagnetically induced transparency (EIT) or coherent population trapping (CPT) experiments, where the light shifts induced by all participating optical fields have to be taken into account. Our results may be of importance for future precision measurements in addition to or in combination with current EIT and CPT-type devices which are largely compatible with our approach and could benefit from the inherent robustness regarding operational conditions, shape of the resonances or intensity fluctuations in the signal field

Comparing Map Learning between Touchscreen-Based Visual and Haptic Displays: A Behavioral Evaluation with Blind and Sighted Users

The ubiquity of multimodal smart devices affords new opportunities for eyes-free applications for conveying graphical information to both sighted and visually impaired users. Using previously established haptic design guidelines for generic rendering of graphical content on touchscreen interfaces, the current study evaluates the learning and mental representation of digital maps, representing a key real-world translational eyes-free application. Two experiments involving 12 blind participants and 16 sighted participants compared cognitive map development and test performance on a range of spatio-behavioral tasks across three information-matched learning-mode conditions: (1) our prototype vibro-audio map (VAM), (2) traditional hardcopy-tactile maps, and (3) visual maps. Results demonstrated that when perceptual parameters of the stimuli were matched between modalities during haptic and visual map learning, test performance was highly similar (functionally equivalent) between the learning modes and participant groups. These results suggest equivalent cognitive map formation between both blind and sighted users and between maps learned from different sensory inputs, providing compelling evidence supporting the development of amodal spatial representations in the brain. The practical implications of these results include empirical evidence supporting a growing interest in the efficacy of multisensory interfaces as a primary interaction style for people both with and without vision. Findings challenge the long-held assumption that blind people exhibit deficits on global spatial tasks compared to their sighted peers, with results also providing empirical support for the methodological use of sighted participants in studies pertaining to technologies primarily aimed at supporting blind users

Identification of Phytochemical Constituents of Aegle marmelos Responsible for Antimicrobial Activity against Selected Pathogenic Organisms

Antimicrobial activity and phytochemical constituents of an ethanolic extract of Aegle marmelos were investigated. The phytochemical screening of the crude extract revealed the presence of Alkaloids, Cardiac glycosides, Terpenoids, Saponins, Tannis, Flavonoids, and Steroids. The crude ethanolic extract was tested for antimicrobial activity against gram positive organisms of Bacillus subtilis (NCIM: 3471), Staphylococcus aureus (NCIM: 2079), gram negative Escherichia coli (NCIM: 2065) and Pseudomonas aeruginosa (NCIM: 2200) at different concentrations levels of 0.5, 1.0, 1.5, 2.0 and 2.5 mg/ml. At the 2.5 mg/ml concentration, gram negative Escherichia coli exhibits a zone of inhibition about 25.7mm; Pseudomonas aeruginosa 19.9mm; gram positive Staphylococcus aureus 29.0 mm; and Bacillus subtilis, a maximum zone of inhibition about 28.1 mm as compared to the control drug penicillin. Escherichia coli, Pseudomonas aeruginosa and Bacillus subtilis exhibit a maximum zone of inhibition, hence they were considered as susceptible to the plant extracts but Staphylococcus aureus doesn’t exhibit such a zone of inhibition and is therefore considered as resistant

Zero Temperature Dynamics of 2D and 3D Ising Ferromagnets

We consider zero-temperature, stochastic Ising models with nearest-neighbor interactions in two and three dimensions. Using both symmetric and asymmetric initial configurations, we study the evolution of the system with time. We examine the issue of convergence of the dynamics and discuss the nature of the final state of the system. By determining a relation between the median number of spin flips per site, the probability p that a spin in the initial spin configuration takes the value +1, and lattice size, we conclude that in two and three dimensions, the system converges to a frozen (but not necessarily uniform) state when p is not equal to 1/2. Results for p=1/2 in three dimensions are consistent with the conjecture that the system does not evolve towards a fully frozen limiting state. Our simulations also uncover `striped' and `blinker' states first discussed by Spirin et al., and their statistical properties are investigated.Comment: 17 pages, 12 figure

The Effect of Reduced Evaporator Air Flow on the Performance of a Residential Central Air Conditioner

This paper discusses the measured degradation in performance of a residential air conditioning system operating under reduced evaporator air flow. Experiments were conducted using a R-22 three-ton split-type cooling system with a short-tube orifice expansion device. Results are presented here for a series of tests in which the evaporator air flow was reduced from 25 to 90% below what is normally recommended for this air conditioner. At present, very little information is available which quantifies the performance of a residential cooling system operating under degraded conditions such as reduced evaporator air flow. Degraded performance measurements can provide information which could help electric utilities evaluate the potential impact of system-wide maintenance programs

Monitoring the Performance of a Residential Central Air Conditioner under Degraded Conditions on a Test Bench

This report presents the measured degradation in performance of a residential air conditioning system operating under degraded conditions. Experiments were conducted using a R-22 threeton split-type cooling system with a short-tube orifice expansion device. Results are presented here for a series of tests in which the various commonly occurring degraded conditions were simulated on a test bench. At present, very little information is available which quantifies the performance of a residential cooling system operating under degraded conditions. Degraded performance measurements can provide information which could help electric utilities evaluate the potential impact of systemwide maintenance programs. This report also discuss the development of a diagnostic procedure based on measurement of refrigerant and air side temperatures

Multi-Response Optimization of WEDM Process Parameters for Machining of Superelastic Nitinol Shape-Memory Alloy Using a Heat-Transfer Search Algorithm

Nitinol, a shape-memory alloy (SMA), is gaining popularity for use in various applications. Machining of these SMAs poses a challenge during conventional machining. Henceforth, in the current study, the wire-electric discharge process has been attempted to machine nickel-titanium (Ni55.8Ti) super-elastic SMA. Furthermore, to render the process viable for industry, a systematic approach comprising response surface methodology (RSM) and a heat-transfer search (HTS) algorithm has been strategized for optimization of process parameters. Pulse-on time, pulse-off time and current were considered as input process parameters, whereas material removal rate (MRR), surface roughness, and micro-hardness were considered as output responses. Residual plots were generated to check the robustness of analysis of variance (ANOVA) results and generated mathematical models. A multi-objective HTS algorithm was executed for generating 2-D and 3-D Pareto optimal points indicating the non-dominant feasible solutions. The proposed combined approach proved to be highly effective in predicting and optimizing the wire electrical discharge machining (WEDM) process parameters. Validation trials were carried out and the error between measured and predicted values was negligible. To ensure the existence of a shape-memory effect even after machining, a differential scanning calorimetry (DSC) test was carried out. The optimized parameters were found to machine the alloy appropriately with the intact shape memory effect