Fast and exact search for the partition with minimal information loss

In analysis of multi-component complex systems, such as neural systems, identifying groups of units that share similar functionality will aid understanding of the underlying structures of the system. To find such a grouping, it is useful to evaluate to what extent the units of the system are separable. Separability or inseparability can be evaluated by quantifying how much information would be lost if the system were partitioned into subsystems, and the interactions between the subsystems were hypothetically removed. A system of two independent subsystems are completely separable without any loss of information while a system of strongly interacted subsystems cannot be separated without a large loss of information. Among all the possible partitions of a system, the partition that minimizes the loss of information, called the Minimum Information Partition (MIP), can be considered as the optimal partition for characterizing the underlying structures of the system. Although the MIP would reveal novel characteristics of the neural system, an exhaustive search for the MIP is numerically intractable due to the combinatorial explosion of possible partitions. Here, we propose a computationally efficient search to precisely identify the MIP among all possible partitions by exploiting the submodularity of the measure of information loss. Mutual information is one such submodular information loss functions, and is a natural choice for measuring the degree of statistical dependence between paired sets of random variables. By using mutual information as a loss function, we show that the search for MIP can be performed in a practical order of computational time for a reasonably large system. We also demonstrate that MIP search allows for the detection of underlying global structures in a network of nonlinear oscillators

Real-Time Water Quality Monitoring with Chemical Sensors

Water quality is one of the most critical indicators of environmental pollution and it affects all of us. Water contamination can be accidental or intentional and the consequences are drastic unless the appropriate measures are adopted on the spot. This review provides a critical assessment of the applicability of various technologies for real-time water quality monitoring, focusing on those that have been reportedly tested in real-life scenarios. Specifically, the performance of sensors based on molecularly imprinted polymers is evaluated in detail, also giving insights into their principle of operation, stability in real on-site applications and mass production options. Such characteristics as sensing range and limit of detection are given for the most promising systems, that were verified outside of laboratory conditions. Then, novel trends of using microwave spectroscopy and chemical materials integration for achieving a higher sensitivity to and selectivity of pollutants in water are described

Digital Signal Processing

Contains table of contents for Part III, table of contents for Section 1, an introduction and reports on seventeen research projects.National Science Foundation FellowshipNational Science Foundation (Grant ECS 84-07285)National Science Foundation (Grant MIP 87-14969)U.S. Navy - Office of Naval Research (Contract N00014-81-K-0742)Scholarship from the Federative Republic of BrazilU.S. Air Force - Electronic Systems Division (Contract F19628-85-K-0028)AT&T Bell Laboratories Doctoral Support ProgramCanada, Bell Northern Research ScholarshipCanada, Fonds pour la Formation de Chercheurs et I'Aide a la Recherche Postgraduate FellowshipSanders Associates, Inc.OKI Semiconductor, Inc.Tel Aviv University, Department of Electronic SystemsU.S. Navy - Office of Naval Research (Contract N00014-85-K-0272)Natural Sciences and Engineering Research Council of Canada, Science and Engineering Scholarshi

The DArk Matter Particle Explorer mission

The DArk Matter Particle Explorer (DAMPE), one of the four scientific space science missions within the framework of the Strategic Pioneer Program on Space Science of the Chinese Academy of Sciences, is a general purpose high energy cosmic-ray and gamma-ray observatory, which was successfully launched on December 17th, 2015 from the Jiuquan Satellite Launch Center. The DAMPE scientific objectives include the study of galactic cosmic rays up to $\sim 10$ TeV and hundreds of TeV for electrons/gammas and nuclei respectively, and the search for dark matter signatures in their spectra. In this paper we illustrate the layout of the DAMPE instrument, and discuss the results of beam tests and calibrations performed on ground. Finally we present the expected performance in space and give an overview of the mission key scientific goals.Comment: 45 pages, including 29 figures and 6 tables. Published in Astropart. Phy

Tailoring Thermoresponsive Poly(N-Isopropylacrylamide) Toward Sensing Perfluoroalkyl Acids

Widespread distribution of poly- and perfluoroalkyl substances (PFAS) in the environment combined with concerns for their potentially negative health effects has motivated regulators to establish strict standards for their surveillance. The United States Environmental Protection Agency issued a cumulative domestic threshold of 70 ppt for water supplies, and this bar is even lower in some local districts and other countries. Monitoring PFAS consequently requires sensitive analytical equipment to meet regulatory specifications, and liquid chromatography with tandem mass spectroscopy (LC/MS/MS) is the most common technique used to satisfy these requirements. Though extremely sensitive, the instrument is often burdened by pretreatment regimens, sedentation, and user proficiency barriers that encumber or limit its effectiveness. As an alternative, polymeric strategies for detecting PFAS are promising candidates for funneling recognition, transduction, and receptor elements into a single sensing platform to overcome some of the hurdles affecting LC/MS/MS. Toward this end, poly(N-isopropylacrylamide) (PNIPAM), an extensively studied thermoresponsive polymer, is a hydrogel with tailorable swelling properties dependent upon its polymeric composition and surrounding media. This polymer holds a lower critical solution temperature (LCST) around 32 °C that marks its transition from a relatively hydrophilic, swollen state to a hydrophobic, collapsed state once heated, and prior research indicates that surfactants such as sodium dodecyl sulfate can heavily influence the temperature at which this transition occurs and the ultimate swelling ratio for crosslinked hydrogels. Two particularly concerning fluorosurfactants, perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS), were hypothesized to act similarly to their non-fluorinated analogs by augmenting the swelling of PNIPAM in a dose-dependent manner. The effect of these fluoropollutants on PNIPAM was therefore studied to identify 1) if PFOS and PFOA would have an appreciable effect on the swelling behavior of varying PNIPAM morphologies, 2) if the swelling response could be enhanced by adding functional comonomers into the PNIPAM backbone, and 3) if the swelling behavior could be outfitted with Förster resonance energy transfer (FRET)-compatible dyes to signal the contaminants’ concentration. As such, crosslinked PNIPAM hydrogels were functionalized with fluorinated comonomers to induce fluorine-fluorine attraction amongst the polymers and their analytes to strengthen their recognition capability and microgels were equipped with FRET-capable dyes to achieve a fluorescent transduction motif indicative of the contaminants’ presence. Results indicated that PFOS augments the swelling of PNIPAM hydrogels significantly while PFOA causes microgels to collapse at temperatures below their innate LCST. FRET primarily replicated swelling observations as expected for the distance-mediated fluorescent phenomenon. Though the fluoropollutants generated appreciable swelling perturbations at concentrations within the micromolar range, additional functionalization is necessary to exploit the molecular-level interactions between PNIPAM and target fluorosurfactants to yield detection limits within the range needed for environmental applications

Dual-Readout Calorimetry with Lead Tungstate Crystals

Results are presented of beam tests in which a small electromagnetic calorimeter consisting of lead tungstate crystals was exposed to 50 GeV electrons and pions. This calorimeter was backed up by the DREAM Dual-Readout calorimeter, which measures the scintillation and \v{C}erenkov light produced in the shower development, using two different media. The signals from the crystal calorimeter were analyzed in great detail in an attempt to determine the contributions from these two types of light to the signals, event by event. This information makes it possible to eliminate the dominating source of fluctuations and thus achieve an important improvement in hadronic calorimeter performance.Comment: Preprint submitted to Nucl. Instrum. Meth. on July 23, 200

MIP-based sensors: Promising new tools for cancer biomarker determination

Detecting cancer disease at an early stage is one of the most important issues for increasing the survival rate of patients. Cancer biomarker detection helps to provide a diagnosis before the disease becomes incurable in later stages. Biomarkers can also be used to evaluate the progression of therapies and surgery treatments. In recent years, molecularly imprinted polymer (MIP) based sensors have been intensely investigated as promising analytical devices in several fields, including clinical analysis, offering desired portability, fast response, specificity, and low cost. The aim of this review is to provide readers with an overview on recent important achievements in MIP-based sensors coupled to various transducers (e.g., electrochemical, optical, and piezoelectric) for the determination of cancer biomarkers by selected publications from 2012 to 2016