Mitigation of artifacts due to isolated acoustic heterogeneities in photoacoustic computed tomography using a variable data truncation-based reconstruction method

Photoacoustic computed tomography (PACT) is an emerging computed imaging modality that exploits optical contrast and ultrasonic detection principles to form images of the absorbed optical energy density within tissue. If the object possesses spatially variant acoustic properties that are unaccounted for by the reconstruction method, the estimated image can contain distortions. While reconstruction methods have recently been developed to compensate for this effect, they generally require the object's acoustic properties to be known a priori. To circumvent the need for detailed information regarding an object's acoustic properties, we previously proposed a half-time reconstruction method for PACT. A half-time reconstruction method estimates the PACT image from a data set that has been temporally truncated to exclude the data components that have been strongly aberrated. However, this method can be improved upon when the approximate sizes and locations of isolated heterogeneous structures, such as bones or gas pockets, are known. To address this, we investigate PACT reconstruction methods that are based on a variable data truncation (VDT) approach. The VDT approach represents a generalization of the half-time approach, in which the degree of temporal truncation for each measurement is determined by the distance between the corresponding ultrasonic transducer location and the nearest known bone or gas void location. Computer-simulated and experimental data are employed to demonstrate the effectiveness of the approach in mitigating artifacts due to acoustic heterogeneities

An Analysis of Rank Ordered Data

Many methods are available to analyze rank ordered data. We used a spectral density method to analyze Formosan subterranean termite control options ranked by Louisiana homeowners. Respondents are asked to rank termite control options from the most preferred to the least preferred option. Spectral analysis results indicated that the most preferred termite control choice is a relatively cheap ($0.13 per square foot) option of liquid treatment.FST, rank ordered data, spectral analysis, Research Methods/ Statistical Methods,

Dynamical Generation of Floquet Majorana Flat Bands in S-Wave Superconductors

We present quantum control techniques to engineer flat bands of symmetry-protected Majorana edge modes in s -wave superconductors. Specifically, we show how periodic control may be employed for designing time-independent effective Hamiltonians, which support Floquet Majorana flat bands, starting from equilibrium conditions that are either topologically trivial or only support individual Majorana pairs. In the first approach, a suitable modulation of the chemical potential simultaneously induces Majorana flat bands and dynamically activates a pre-existing chiral symmetry which is responsible for their protection. In the second approach, the application of effective parity kicks dynamically generates a desired chiral symmetry by suppressing chirality- breaking terms in the static Hamiltonian. Our results demonstrate how the use of time-dependent control enlarges the range of possibilities for realizing gapless topological superconductivity, potentially enabling access to topological states of matter that have no known equilibrium counterpart

Price variation among different brands of anticancer medicines available in hospital pharmacies of Nepal.

Objective:To assess the variation in price among different brands of anticancer medicines available in hospital pharmacies at Nepalese cancer hospitals. Methods:The price of different brands of the same anticancer medicines available in the hospital pharmacies of two cancer hospitals was assessed. Prices of different dosage forms such as a single tablet, capsule and vial were calculated. The difference in the maximum and minimum price of the same drug manufactured by different pharmaceutical industries was determined, and the percentage variation in price was calculated. The prices of medicines (brands) were also compared with the price determined by the government where available. Results:Price variation was assessed for 31 anticancer medicines belonging to six broad categories. Prices were found to vary maximally among the following medicines, each belonging to separate categories: among alkylating agents, the price of temozolomide 100 mg capsule varied 308%; among antimetabolite agents, the price of pemetrexed 500 mg injection varied 134%; among hormonal drugs, the price of letrozole 2.5 mg tablet varied 200%; among antibody class, the price of trastuzumab 440 mg injection varied 73%; among natural products, the price of irinotecan 100 mg injection varied 590%; and among miscellaneous agents, the price of bortezomib 2 mg injection varied 241%. There was a significant difference in the mean MRP of the alkylating agents with the antimetabolites (p-value 0.006) and the monoclonal antibody (p-value <.001). Antimetabolites, natural products, hormonal therapy all had significant mean differences in their MRPs with the monoclonal antibodies. (p-value <.001) and the monoclonal antibodies had a significant mean difference in the MRP with the miscellaneous agents. (p-value <.001). Conclusions:There was a considerable variation in the price of different brands of anticancer medicines available in the Nepalese market. The Government of Nepal has regulated the prices of some medicines, including anticancer medicine. However, it is not enough as prices of the majority of anticancer medicines are still not regulated. Therefore, further strategies are needed to address the variation in the prices of anticancer medicines available in the Nepalese market

A Novel Statistical Method to Diagnose, Quantify and Correct Batch Effects in Genomic Studies.

Genome projects now generate large-scale data often produced at various time points by different laboratories using multiple platforms. This increases the potential for batch effects. Currently there are several batch evaluation methods like principal component analysis (PCA; mostly based on visual inspection), and sometimes they fail to reveal all of the underlying batch effects. These methods can also lead to the risk of unintentionally correcting biologically interesting factors attributed to batch effects. Here we propose a novel statistical method, finding batch effect (findBATCH), to evaluate batch effect based on probabilistic principal component and covariates analysis (PPCCA). The same framework also provides a new approach to batch correction, correcting batch effect (correctBATCH), which we have shown to be a better approach to traditional PCA-based correction. We demonstrate the utility of these methods using two different examples (breast and colorectal cancers) by merging gene expression data from different studies after diagnosing and correcting for batch effects and retaining the biological effects. These methods, along with conventional visual inspection-based PCA, are available as a part of an R package exploring batch effect (exploBATCH; https://github.com/syspremed/exploBATCH )