SYNTHESIS OF GOLD NANOPARTICLES VIA PULSED LIQUID ABLATION FOR USE IN THE PHOTODYNAMIC THERAPY OF BACTERIA

With the ever-increasing threat of antibiotic resistant bacteria, alternative treatment methods have been developed including photodynamic therapy (PDT). Within the PDT process, photosensitizers are used to generate reactive oxygen species (ROS) and facilitate the cell termination process. This work lays the conceptual foundation for the functionalization of the photosensitizer methylene blue (MB) with gold nanoparticles (AuNPs) and INF-55 as a potential inhibitor of the AcrAB-TolC efflux pump to enhance the effectivity of the PDT process. AuNPs were synthesized using pulsed laser ablation in an aqueous citrate solution. Both nanosecond and picosecond pulse durations, as well as both 532 nm and 1064 nm wavelengths at various powers and frequencies were tested to determine the effect of laser parameters on particle synthesis. The nanosecond, 532 nm, 2.0 W laser parameters were determined to produce the most viable AuNPs for application in PDT with an average Feret diameter of 7.46 ± 3.28 nm. After synthesis, the AuNPs were characterized using transmission electron microscopy imaging, UV-Visible spectroscopy, fluorescence spectroscopy, and Fourier transform infrared (FTIR) Spectroscopy. After synthesis and characterization of the AuNPs, the ROS generated in solution was measured by monitoring the photobleaching of 9,10-Anthracenediyl-bis(methylene)dimalonic Acid (ABMDMA). Molecular docking calculations were conducted to determine the viability of INF-55 as a competitive inhibitor for the AcrB subunit. The most probable binding mode for INF-55 had a binding affinity of –9.1 kcal/mol while the most probable binding mode for MB had a binding affinity of –7.2 kcal/mol. Additionally, AuNPs were used in combination with MB in-vitro on the Gram-negative bacteria Escherichia coli (E. coli) to determine the effect of AuNPs on cell termination. When AuNPs were used with MB, a 99.98 - 99.99 % decrease in the bacteria concentration was observed as compared to a 97.51 % decrease with MB alone

Image interpretation above and below the object level

Computational models of vision have advanced in recent years at a rapid rate, rivaling in some areas human- level performance. Much of the progress to date has focused on analyzing the visual scene at the object level – the recognition and localization of objects in the scene. Human understanding of images reaches a richer and deeper image understanding both ‘below’ the object level, such as identifying and localizing object parts and sub-parts, as well as ‘above’ the object levels, such as identifying object relations, and agents with their actions and interactions. In both cases, understanding depends on recovering meaningful structures in the image, their components, properties, and inter-relations, a process referred here as ‘image interpretation’. In this paper we describe recent directions, based on human and computer vision studies, towards human-like image interpretation, beyond the reach of current schemes, both below the object level, as well as some aspects of image interpretation at the level of meaningful configurations beyond the recognition of individual objects, in particular, interactions between two people in close contact. In both cases the recognition process depends on the detailed interpretation of so-called 'minimal images', and at both levels recognition depends on combining ‘bottom-up’ processing, proceeding from low to higher levels of a processing hierarchy, together with ‘top-down’ processing, proceeding from high to lower levels stages of visual analysis.This work was supported by the Center for Brains, Minds and Machines (CBMM), funded by NSF STC award CCF-1231216

The Birth-Death-Mutation process: a new paradigm for fat tailed distributions

Fat tailed statistics and power-laws are ubiquitous in many complex systems. Usually the appearance of of a few anomalously successful individuals (bio-species, investors, websites) is interpreted as reflecting some inherent "quality" (fitness, talent, giftedness) as in Darwin's theory of natural selection. Here we adopt the opposite, "neutral", outlook, suggesting that the main factor explaining success is merely luck. The statistics emerging from the neutral birth-death-mutation (BDM) process is shown to fit marvelously many empirical distributions. While previous neutral theories have focused on the power-law tail, our theory economically and accurately explains the entire distribution. We thus suggest the BDM distribution as a standard neutral model: effects of fitness and selection are to be identified by substantial deviations from it

Word-Slam Stories as Venues for Stimulating Learning and Developing Agency with Urban High School Students

Word-slam was used with our high school urban students as instrument and method to elicit engagement with learning and develop agency through personal storytelling. The word-slam text (as it appears on YouTube and in hard-copy format as well) was chosen due to its being a personal story and an alternative, artistic and critical form of text that our students could relate to directly as the format and content were relevant to their lives and experiences. By using the text as a mentor text and studying the author’s craft together, students were able to write, rewrite and develop their own word-slam stories, carving out a space for themselves to be seen and heard

Oscillatory activity, phase differences, and phase resetting in the inferior olivary nucleus

© 2013 Lefler, Torben-Nielsen and Yarom. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in other forums, provided the original authors and source are credited and subject to any copyright notices concerning any third-party graphics etcThe generation of temporal patterns is one of the most fascinating functions of the brain. Unlike the response to external stimuli temporal patterns are generated within the system and recalled for a specific use. To generate temporal patterns one needs a timing machine, a "master clock" that determines the temporal framework within which temporal patterns can be generated and implemented. Here we present the concept that in this putative "master clock" phase and frequency interact to generate temporal patterns. We define the requirements for a neuronal "master clock" to be both reliable and versatile. We introduce this concept within the inferior olive nucleus which at least by some scientists is regarded as the source of timing for cerebellar function. We review the basic properties of the subthreshold oscillation recorded from olivary neurons, analyze the phase relationships between neurons and demonstrate that the phase and onset of oscillation is tightly controlled by synaptic input. These properties endowed the olivary nucleus with the ability to act as a "master clock."Peer reviewedFinal Published versio

Full interpretation of minimal images

The goal in this work is to model the process of ‘full interpretation’ of object images, which is the ability to identify and localize all semantic features and parts that are recognized by human observers. The task is approached by dividing the interpretation of the complete object to the interpretation of multiple reduced but interpretable local regions. In such reduced regions, interpretation is simpler, since the number of semantic components is small, and the variability of possible configurations is low. We model the interpretation process by identifying primitive components and relations that play a useful role in local interpretation by humans. To identify useful components and relations used in the interpretation process, we consider the interpretation of ‘minimal configurations’: these are reduced local regions, which are minimal in the sense that further reduction renders them unrecognizable and uninterpretable. We show that such minimal interpretable images have useful properties, which we use to identify informative features and relations used for full interpretation. We describe our interpretation model, and show results of detailed interpretations of minimal configurations, produced automatically by the model. Finally, we discuss implications of full interpretation to difficult visual tasks, such as recognizing human activities or interactions, which are beyond the scope of current models of visual recognition.This work was supported by the Center for Brains, Minds and Machines (CBMM), funded by NSF STC award CCF-1231216