Label-free, single molecule detection of cytokines using optical microcavities

Interleukin-2 (IL2) is a cytokine that regulates T-cell growth and is used in cancer therapies. By sensitizing a microcavity sensor surface with anti-IL2 and monitoring the resonant frequency, single molecules of IL2 can be detected

Label-free detection of cytokines using optical microcavities

Ultra-high-Q microresonators have demonstrated sensitive and specific chemical and biological detection. The sensitivity is derived from the long photon lifetime inside the cavity and specificity is achieved through surface functionalization. Here, ultra-high-Q microcavities demonstrate label-free, single molecule detection of Interleukin-2 (IL-2) in fetal bovine serum (FBS). IL-2 is a cytokine released in response to immune system activation. The surface of the microtoroids was sensitized using anti-IL-2. The detection mechanism relies upon a thermo-optic mechanism to enhance resonant wavelength shifts induced through binding of a molecule

Oral Communication: Generating Network Data for Automated Unit Test Generation

Although automated unit test generation techniques can in principle generate test suites that achieve high code coverage, in practice this is often inhibited by the dependence of the code under test on external resources. In particular, a common problem in modern programming languages is posed by code that involves networking (e.g., opening a TCP listening port). In order to generate tests for such code, we describe an approach where we mock (simulate) the networking interfaces of the Java standard library, such that a search-based test generator can treat the network as part of the test input space.Sociedad Argentina de Informática e Investigación Operativ

BioMeT and algorithm challenges: A proposed digital standardized evaluation framework

Technology is advancing at an extraordinary rate. Continuous flows of novel data are being generated with the potential to revolutionize how we better identify, treat, manage, and prevent disease across therapeutic areas. However, lack of security of confidence in digital health technologies is hampering adoption, particularly for biometric monitoring technologies (BioMeTs) where frontline healthcare professionals are struggling to determine which BioMeTs are fit-for-purpose and in which context. Here, we discuss the challenges to adoption and offer pragmatic guidance regarding BioMeTs, cumulating in a proposed framework to advance their development and deployment in healthcare, health research, and health promotion. Furthermore, the framework proposes a process to establish an audit trail of BioMeTs (hardware and algorithms), to instill trust amongst multidisciplinary users

Label-free single-molecule all-optical sensor

Recently, quality factors greater than 100 million were demonstrated using planar arrays of silica microtoroid resonators. These high Q factors allow the toroidal resonators to perform very sensitive detection experiments. By functionalizing the silica surface of the toroid with biotin, the toroidal resonators become both specific and sensitive detectors for Streptavidin. One application of this sensor is performing detection in lysates. To mimic this type of environment, additional solutions of Streptavidin were prepared which also contained high concentrations (nM and μM) of tryptophan

Characterization of high-Q optical microcavities using confocal microscopy

Confocal microscopy was initially developed to image complex circuits and material defects. Previous imaging studies yielded only qualitative data about the location and number of defects. In the present study, this noninvasive method is used to obtain quantitative information about the Q factor of an optical resonant cavity. Because the intensity of the fluorescent signal measures the number of defects in the resonant cavity, this signal is a measure of the number of surface scattering defects, one of the dominant loss mechanisms in optical microcavities. The Q of the cavities was also determined using conventional linewidth measurements. Based upon a quantitative comparative analysis of these two techniques, it is shown that the Q can be determined without a linewidth measurement, allowing for a noninvasive characterization technique

Assessing Bacterial Community Assembly and Function for Improved Biological Removal of Pathogens and Contaminants in Stormwater Filtration Systems

Pathogens and nutrients are consistently top pollutants of waterbodies around the world. Stormwater runoff is a major source of these pollutants, though with proper treatment, such as engineered filtration, water quality can potentially be improved for safe infiltration, discharge or reuse of runoff. Microorganisms are ubiquitous in stormwater, thus microbial community development on filtration based remediation systems requires consistent maintenance, which is far from optimized in practice. Previous work has demonstrated that biofilm microorganisms that colonize stormwater filters can lead to biofouling, as well as differ substantially in their remediation potential. However, few studies have investigated either the variation of the community in stormwater, or tested remediation ability with natural communities that are representative of variation from different potential treatment locations. Here we assessed the natural bacterial community structure variability of urban stormwater with 16S rRNA gene sequencing at a variety of runoff locations. We inferred the presence of potential pathogens and organisms associated with remediation functions (e.g. denitrification) from their sequence classification. Overall, we found high variability in stormwater bacterial community structure across rooftop, roadway, and Municipal Separate Storm Sewer outfall samples, but substantially less variability in potential for contaminant remediation. We also tested whether microbial community functional potential (e.g. pathogen presence and nitrate removal) in experimental filtration systems was sensitive to inoculum community composition, deposition and drift during biofilm assembly in experimental filtration columns. Potentially pathogenic and denitrifying organisms increased in total abundance in experimental filtration columns over a one month growth period. Additionally, inoculation of filters with stormwater microbial communities provided significantly better pathogen removal than single isolate, sand, and control columns. Filters inoculated with stormwater communities performed similarly despite substantial taxonomic differences in inoculum communities taken from different runoff locations. Model pathogen initial removal performance had significant correlation with inoculum community diversity while biofilm presence was anti-correlated with the amount of E. coli remobilized in a subsequent simulated storm event. A similar approach could be used to investigate other pathogens of concern, varied chemistry and environmental conditions associated with stormwater or drinking, waste and other water treatment systems

Time varying Na I D absorption in ILRTs as a probe of circumstellar material

Intermediate-Luminosity Red Transients (ILRTs) are a class of observed transient posited to arise from the production of an electron-capture supernova from a super-asymptotic giant branch star within a dusty cocoon. In this paper, we present a systematic analysis of narrow Na I D absorption as a means of probing the circumstellar environment of these events. We find a wide diversity of evolution in ILRTs in terms of line strength, time-scale, and shape. We present a simple toy model designed to predict this evolution as arising from ejecta from a central supernova passing through a circumstellar environment wherein Na II is recombining to Na I over time. We find that while our toy model can qualitatively explain the evolution of a number of ILRTs, the majority of our sample undergoes evolution more complex than predicted. The success of using the Na I D doublet as a diagnostic tool for studying circumstellar material will rely on the availability of regular high-resolution spectral observations of multiple ILRTs, and more detailed spectral modelling will be required to produce models capable of explaining the diverse range of behaviours exhibited by ILRTs. In addition, the strength of the Na I D absorption feature has been used as a means of estimating the extinction of sources, and we suggest that the variability visible in ILRTs would prevent such methods from being used for this class of transient, and any others showing evidence of variabilityComment: 14 pages, 10 figures, submitted to MNRA