Anna Pyayt

A real-time classification algorithm for emotion detection using portable EEG

Military personnel, airplane pilots, and bus drivers often operate in stressful conditions when something unexpected can happen and cause dangerous consequences if they do not respond properly. Additionally, stress adversely affects human decision making abilities, therefore prompt, preferably real-time detection of fear is very important. Based on previous studies for non-portable multi-electrode electroencephalography (EEG) systems the ratio of the power of the slow waves to that of the fast waves increases when a person is relaxed and decreases when s/he is scared. In this study we test small portable EEG and develop algorithms for real time detection of the stressful condition - fear. During the experiment we compare EEG signals of subjects in relaxed state with those in stressed state while they are watching a scene from a scary movie. The ratio of the slow/fast wave powers was measured and the observed pattern was similar to one obtained using a multi-electrode system. We integrate stream-processing algorithms in the system to ensure real-time detection of any changes in mental condition and timely generate the alarm event.

READFAST: high-relevance search-engine for big text

Relevance of search-results is a key factor for any search engine. In order to return and rank the Web-pages that are most relevant to the query, contemporary search engines use complex ranking functions that depend on hundreds of features. For example, presence or absence of the query keywords on the page, their proximity, frequencies, HTML markup are just a few to name. Additional features might include fonts, tags, hyperlinks, metadata, and parts of the Web-page description. All this information is used by the search-engine to rank HTML Web pages returned to the user, but is unfortunately absent in free text that has no HTML markup, tags, hyperlinks, and any other metadata, except implicit natural language structure. Here we demonstrate one of the first Big text search engines that leverages hidden structure of the natural language sentences in order to process user queries and return more relevant search-results than a standard keyword-search. It provides a structured index extracted from the text using Natural Language Processing (NLP) that can be used to browse and query free text.

Dynamic visualization of photothermal heating by gold nanocages using thermoresponsive elastin like polypeptides.

Understanding how plasmonic nanoparticles collectively generate heat upon exposure to light and thus increase the local temperature of the surrounding medium is critical for many applications such as plasmon-assisted microfluidics, plasmonic tweezers, and photothermal cancer therapy. Reliable temperature manipulation requires the capability to spatially and dynamically analyze local temperature profiles as a function of nanoparticle concentration and laser intensity. In this work, we present a novel method for visualization of local temperature increase using elastin-like polypeptides (ELP). We also propose a robust algorithm that allows the construction of reliable calibration curves using known boundary conditions and Boltzmann sigmoid fit applied to the ELP solutions temperature-absorption transfer function. Using this technique, for the first time, we successfully demonstrated how surface and volume distribution of the nano-heaters affect collective heat generation. This approach allows the visualization of dynamic 2D-temperature profiles and simultaneously enables the measurement of specific temperature at any point in a 2D-map. The experimental setup is compatible with conventional optical microscopy and requires no specialized hardware or complex sample preparation. Finally, the real time visualization of plasmonic heating offers an opportunity to control outcomes of thermo-plasmonics which enables a myriad of practical applications.

Optimization of light delivery by a nanowire-based single cell optical endoscope

Here we present a new design and FDTD simulations of light delivery by a nanowire-based intracellular endoscope. Nanowires can be used for minimally invasive and very local light delivery inside cells. One of the main challenges is coupling of light into the nanowire. We propose a new plasmonic coupler interface between cleaved optical fiber and a nanowire, and optimize light coupling efficiency and contrast.

A mobile phone-based approach to detection of hemolysis

Preeclampsia and HELLP (hemolysis, elevated liver enzymes, and low platelet count) syndrome are pregnancy-related complications with high rates of morbidity and mortality. HELLP syndrome, in particular, can be difficult to diagnose. Recent work suggests that elevated levels of free cell hemoglobin in blood plasma can, as early as the first trimester, potentially serve as a diagnostic biomarker for impending complications. We therefore developed a point-of-care mobile phone-based platform that can quickly characterize a patients level of hemolysis by measuring the color of blood plasma. The custom hardware and software are designed to be easy to use. A sample of the whole blood (~10µL or less) is first collected into a clear capillary tube or microtube, which is then inserted into a low-cost 3D-printed sample holder attached to the phone. A 5-10min period of quiescence allows for gravitational sedimentation of the red blood cells, leaving a layer of yellowish plasma at the top of the tube. The phone camera then photographs the capillary tube and analyzes the color components of the cell-free plasma layer. The software converts these color values to a concentration of free hemoglobin, based on a built-in calibration curve, and reports the patients hemolysis level: non-hemolyzed, slightly hemolyzed, mildly hemolyzed, frankly hemolyzed, or grossly hemolyzed.. The accuracy of the method is ~1mgdL-1. This phone-based point-of-care system provides the potentially life-saving advantage of a turnaround time of about 10min (versus 4+hours for conventional laboratory analytical methods) and a cost of approximately one dollar USD (assuming you have the phone and the software are already available).

Photonic crystal based microscale flow cytometry.

Here we propose a new design of an on-chip micro-flow cytometry based on photonic crystals. When individual cells flow tangential to the crystal surface, the transmission of the light through the photonic crystal changes depending on the presence or absence of the cells and their size and shape. This system was modeled using OptiFDTD, where transmission spectra were extracted. Initially, the potential for cell counting has been demonstrated. Then, for cells with differing shape a direct relation between signal distribution and cell shape has been found.

Design and fabrication of a SAW device with Ta filled microcavities inserted into its delay path for improved power transfer

The authors report the design and fabrication of a surface acoustic wave (SAW) device with improved power transfer due to modification of its delay path. Typically, SAW delay-line devices suffer from relatively high insertion loss (IL) (∼10–30 dB). Our approach is to incorporate an array of microcavities, having square cross-sectional area (λ/2 × λ/2) and filled with tantalum, within the delay path to maximize acoustic confinement to the surface and reduce IL. To determine the effectiveness of the cavities without expending too many resources and to explain trends found in actual devices, a finite element model of a SAW device with tantalum filled cavities having various depths was utilized. For each depth simulated, IL was decreased compared to a standard SAW device. Microcavities 2.5 μm deep filled with tantalum showed the best performance (ΔIL = 17.93 dB). To validate simulated results, the authors fabricated a SAW device on ST 90°-X quartz with microcavities etched into its delay path using deep react...

Mobile phone based ELISA (MELISA)

Enzyme-linked immunosorbent assay (ELISA) is one of the most important technologies for biochemical analysis critical for diagnosis and monitoring of many diseases. Traditional systems for ELISA incubation and reading are expensive and bulky, thus cannot be used at point-of-care or in the field. Here, we propose and demonstrate a new miniature mobile phone based system for ELISA (MELISA). This system can be used to complete all steps of the assay, including incubation and reading. It weighs just 1 pound, can be fabricated at low cost, portable, and can transfer test results via mobile phone. We successfully demonstrated how MELISA can be calibrated for accurate measurements of progesterone and demonstrated successful measurements with the calibrated system.

ReadFast: Optimizing structural search relevance for big biomedical text

While the problem to find needed information on the Web is critical, it is arguably much less pressing nowadays than it was over a decade ago when the Web was emerging. Back then it was much more difficult to find a Web resource of interest, because the search engines were in their infancy covering much lesser portion of the Web by their indices, armed with embryonic page ranking algorithms. Now, Web-search is by far not perfect yet, but definitely went a long way to become an everyday “go-to” resource for millions of people. By contrast, access to textual information is not even close to what Web-search algorithms offer today. In fact, it does not differ much from what everyone had a decade ago. That is keyword-search (exact substring match) is often the only way to find needle in a haystack in most modern word processors and text corpora search engines. Here we demonstrate ReadFast - a system, capable to extract certain structure from any natural language text corpus and use it to provide more relevant search results than keyword-search for specific classes of queries. Our evaluation justified significant relevance gain (20-30%) for two large Biomedical text corpora.

Plasmono-magnetic material for precise photothermal heating

Noble metal nanoparticles have been extensively studied as photo-sensitive agents for photothermal cancer therapy. Precise control over the size and shape of the nanoparticles allowed strong optical absorption and efficient heat generation necessary for destroying a tumor to be achieved. However, one of the fundamental challenges of application of the nanoparticles towards photothermal cancer therapy is low specificity in the targeting tumor tissue in comparison with the healthy tissue and the resulting unfavorable biodistribution of the nanoparticles. Additional levels of control over particle distribution can be achieved by making the particles magnetic and using external magnets to control their accumulation in a tumor. Since the direct synthesis of particles with a magnetic core and a metallic shell limits the options for design and fine-tuning of plasmonic properties, the alternative approaches to the design of such materials have to be investigated. Here we propose and demonstrate a new design of a hybrid plasmono-magnetic material for photothermal heating created by grafting Au nanocages onto a surface of magnetic micro-beads. Next, we confirm its dual functionality in in vitro studies and show that individual hybrid particles can be magnetically controlled with a precision of a few micrometers and precisely destroy individual cells using plasmonic heating.