Statistical Modeling of Bit-Error-Rates in Asynchronous Multicarrier CDMA and Direct-Sequence CDMA Systems

This paper presents a method for modeling the bit-error-rate (BER) probability density functions (pdf) of asynchronous Multicarrier Code Division Multiple Access (MC-CDMA) and Direct-Sequence Code Division Multiple Access (DS-CDMA) systems. An uplink channel is considered and it is assumed that the only channel distortion introduced by the channel is caused by the timing misalignments. Deterministic spreading sequences are used and the pdfs of each interferer'’s multiple access interference (MAI) are determined as a function of timing offset. A Nakagami-m distribution is fitted to the pdf of the total MAI power and the BER pdf is obtained directly from this Nakagami-m pdf. Both Walsh-Hadamard (WH) and Gold sequences are analyzed and the mean BERs are compared amongst the two multiple access systems for both sets of spreading sequences of varying lengths. The results suggest a higher resistance to MAI in the MC-CDMA technique for the considered environment

Statistical Modeling of Multiple Access Interference Power: a Nakagami-m Random Variable

This paper proposes a statistical model for the total multiple access interference (MAI) power for both Direct-Sequence Code Division Multiple Access (DS-CDMA) and Multicarrier Code Division Multiple Access (MC-CDMA) systems. We consider the use of both Walsh-Hadamard (WH) and Gold spreading codes transmitting over the asynchronous uplink channel. Detailed signal models of both CDMA systems are derived illustrating the production of MAI under asynchronous conditions. The paper demonstrates the Gaussian nature of the total MAI and shows that the probability density function (pdf) of the total MAI power can be very accurately characterized by the Nakagami-m distribution

Tuner: a tool for designing and optimizing ion optical systems

Designing and optimizing ion optical systems is often a complex and difficult task, which requires the use of computational tools to iterate and converge towards the desired characteristics and performances of the system. Very often these tools are not well adapted for exploring the numerous degrees of freedom, rendering the process long and tedious, as well as somewhat random due to the very large number of local minima typically found when looking for a particular optical solution. This paper presents a novel approach to finding the desired solution of an optical system, by providing the user with an instant feedback of the effects of changing parameters. The process of finding an approximate solution by manually adjusting parameters is greatly facilitated, at which point the final tune can be calculated by minimization according to a number of constraints.Comment: 15 pages, 6 figures, to be published in Nuclear Instruments and Methods

The Impact of Triclosan on the Spread of Antibiotic Resistance in the Environment

Triclosan (TCS) is a commonly used antimicrobial agent that enters wastewater treatment plants (WWTPs) and the environment. An estimated 1.1 × 105 to 4.2 × 105 kg of TCS are discharged from these WWTPs per year in the United States. The abundance of TCS along with its antimicrobial properties have given rise to concern regarding its impact on antibiotic resistance in the environment. The objective of this review is to assess the state of knowledge regarding the impact of TCS on multidrug resistance in environmental settings, including engineered environments such as anaerobic digesters. Pure culture studies are reviewed in this paper to gain insight into the substantially smaller body of research surrounding the impacts of TCS on environmental microbial communities. Pure culture studies, mainly on pathogenic strains of bacteria, demonstrate that TCS is often associated with multidrug resistance. Research is lacking to quantify the current impacts of TCS discharge to the environment, but it is known that resistance to TCS and multidrug resistance can increase in environmental microbial communities exposed to TCS. Research plans are proposed to quantitatively define the conditions under which TCS selects for multidrug resistance in the environment

Info Navigator: A visualization tool for document searching and browsing

In this paper we investigate the retrieval performance of monophonic and polyphonic queries made on a polyphonic music database. We extend the n-gram approach for full-music indexing of monophonic music data to polyphonic music using both rhythm and pitch information. We define an experimental framework for a comparative and fault-tolerance study of various n-gramming strategies and encoding levels. For monophonic queries, we focus in particular on query-by-humming systems, and for polyphonic queries on query-by-example. Error models addressed in several studies are surveyed for the fault-tolerance study. Our experiments show that different n-gramming strategies and encoding precision differ widely in their effectiveness. We present the results of our study on a collection of 6366 polyphonic MIDI-encoded music pieces

Altered Antibiotic Tolerance in Anaerobic Digesters Acclimated to Triclosan Or Triclocarban

Bench-scale anaerobic digesters were amended to elevated steady-state concentrations of triclosan (850 mg/kg) and triclocarban (150 mg/kg) using a synthetic feed. After more than 9 solids retention time (SRT) values of acclimatization, biomass from each digester (and a control digester that received no antimicrobials) was used to assess the toxicity of three antibiotics. Methane production rate was measured as a surrogate for activity in microcosms that received doses of antibiotics ranging from no-antibiotic to inhibitory concentrations. Biomass amended with triclocarban was more sensitive to tetracycline compared to the control indicating synergistic inhibitory effects between this antibiotic and triclocarban. In contrast, biomass amended with triclosan was able to tolerate statistically higher levels of ciprofloxacin indicating that triclosan can induce functional resistance to ciprofloxacin in an anaerobic digester community

Universally Consistent Latent Position Estimation and Vertex Classification for Random Dot Product Graphs

In this work we show that, using the eigen-decomposition of the adjacency matrix, we can consistently estimate latent positions for random dot product graphs provided the latent positions are i.i.d. from some distribution. If class labels are observed for a number of vertices tending to infinity, then we show that the remaining vertices can be classified with error converging to Bayes optimal using the $k$-nearest-neighbors classification rule. We evaluate the proposed methods on simulated data and a graph derived from Wikipedia

From the plane tree to the gardens of Adonis : plant and garden imagery in Plato’s Phaedrus

Since at least the time the Akkadian version of The Epic of Gilgamesh was preserved in clay tablets nearly four thousand years ago, human beings have weaved plants and gardens into their stories. The way they appear in myth and literature is often as diverse as it is fascinating: they might figure as settings, metaphors, analogies, or be imbued with symbolism. This particular treatment of plants and gardens is not limited to myth and literature though. In a number of Plato’s dialogues he utilises them in a similar way. This essay sets out to think about the plant and garden images in one of Plato’s dialogues; more specifically, the Phaedrus. It seeks to address the following question: what might the plant and garden images in the dialogue mean, and how are we to understand them in relation to the text? We will come to see that during the classical period the plants and gardens mentioned in the dialogue were associated with love, madness, chastity, sterility, death, and more; in short, the whole gamut of themes taken up in the Phaedrus. Since many of these vegetal images appear in the text as part of the dialogue’s setting, this means that as Phaedrus and Socrates converse with one another, they do so surrounded by images of the very things they discuss. We will also discover that the setting of the dialogue seems to influence both the flow of conversation and the language that Socrates uses. It would seem that there is more to the plant and garden imagery in the dialogue than first meets the eye

Matched filters for noisy induced subgraph detection

First author draftWe consider the problem of finding the vertex correspondence between two graphs with different number of vertices where the smaller graph is still potentially large. We propose a solution to this problem via a graph matching matched filter: padding the smaller graph in different ways and then using graph matching methods to align it to the larger network. Under a statistical model for correlated pairs of graphs, which yields a noisy copy of the small graph within the larger graph, the resulting optimization problem can be guaranteed to recover the true vertex correspondence between the networks, though there are currently no efficient algorithms for solving this problem. We consider an approach that exploits a partially known correspondence and show via varied simulations and applications to the Drosophila connectome that in practice this approach can achieve good performance.https://arxiv.org/abs/1803.02423https://arxiv.org/abs/1803.0242