Publications by authors named "Peskin A"

Background: Picky eating commonly co-occurs with disruptive behaviors in young children. While feeding interventions exist, it remains unknown whether unmodified behavioral parent training (BPT) improves maladaptive child eating. As coercive feeding practices may exacerbate picky eating, BPT could ameliorate associated behaviors by increasing authoritative parenting.

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Repeatability of measurements from image analytics is difficult, due to the heterogeneity and complexity of cell samples, exact microscope stage positioning, and slide thickness. We present a method to define and use a reference focal plane that provides repeatable measurements with very high accuracy, by relying on control beads as reference material and a convolutional neural network focused on the control bead images. Previously we defined a reference effective focal plane (REFP) based on the image gradient of bead edges and three specific bead image features.

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To facilitate the characterization of unlabeled induced pluripotent stem cells (iPSCs) during culture and expansion, we developed an AI pipeline for nuclear segmentation and mitosis detection from phase contrast images of individual cells within iPSC colonies. The analysis uses a 2D convolutional neural network (U-Net) plus a 3D U-Net applied on time lapse images to detect and segment nuclei, mitotic events, and daughter nuclei to enable tracking of large numbers of individual cells over long times in culture. The analysis uses fluorescence data to train models for segmenting nuclei in phase contrast images.

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Telehealth treatment for child disruptive behavior has the potential to overcome multiple barriers to access (e.g., transportation, therapist availability).

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Introduction: Disruptive behavior disorders are among the most prevalent pediatric mental health referrals for young children. However, families from historically minoritized social identities have experienced disparities in treatment access, retention, and outcomes. Evidence-based interventions such as Parent-Child Interaction Therapy (PCIT) have been found to be effective in reducing children's disruptive behaviors in minoritized families.

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Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) contains an active site Cys and is one of the most sensitive cellular enzymes to oxidative inactivation and redox regulation. Here, we show that inactivation by hydrogen peroxide is strongly enhanced in the presence of carbon dioxide/bicarbonate. Inactivation of isolated mammalian GAPDH by HO increased with increasing bicarbonate concentration and was sevenfold faster in 25 mM (physiological) bicarbonate compared with bicarbonate-free buffer of the same pH.

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Objective: Parent-child interaction therapy (PCIT) is an effective intervention to address child externalizing behaviors. However, disparities in access and retention are pervasive, which relate to the availability of PCIT in low-income communities, inadequate workforces to provide culturally appropriate care, and distrust in services due to systemic discrimination. This study incorporated natural helpers who had been trained as community health workers into PCIT delivery to improve disparities in engagement and outcomes.

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Trypan blue dye exclusion-based cell viability measurements are highly dependent upon image quality and consistency. In order to make measurements repeatable, one must be able to reliably capture images at a consistent focal plane, and with signal-to-noise ratio within appropriate limits to support proper execution of image analysis routines. Imaging chambers and imaging systems used for trypan blue analysis can be inconsistent or can drift over time, leading to a need to assure the acquisition of images prior to automated image analysis.

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A reconstruction algorithm for partially coherent x-ray computed tomography (XCT) including Fresnel diffraction is developed and applied to an optical fiber. The algorithm is applicable to a high-resolution tube-based laboratory-scale x-ray tomography instrument. The computing time is only a few times longer than the projective counterpart.

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2-Cys peroxiredoxins are abundant thiol proteins that react efficiently with a wide range of peroxides. Unlike other enzymes, their exceptionally high reactivity does not rely on cofactors. The mechanism of oxidation and reduction of peroxiredoxins places them in a good position to act as antioxidants as well as key players in redox signaling.

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Peroxiredoxin 2 (Prdx2) is a thiol peroxidase with an active site Cys (C52) that reacts rapidly with HO and other peroxides. The sulfenic acid product condenses with the resolving Cys (C172) to form a disulfide which is recycled by thioredoxin or GSH via mixed disulfide intermediates or undergoes hyperoxidation to the sulfinic acid. C172 lies near the C terminus, outside the active site.

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Health agencies call for the immediate mobilization of existing interventions in response to numerous child and family mental health concerns that have arisen as result of the COVID-19 pandemic. Answering this call, this pilot study describes the rapid, full-scale change from a primarily clinic-based Parent-Child Interaction Therapy (PCIT) model to a virtual service model (i.e.

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Peroxiredoxin 2 (Prdx2) and other typical 2-Cys Prdxs function as homodimers in which hydrogen peroxide oxidizes each active site cysteine to a sulfenic acid which then condenses with the resolving cysteine on the alternate chain. Previous kinetic studies have considered both sites as equally reactive. Here we have studied Prdx2 using a combination of non-reducing SDS-PAGE to separate reduced monomers and dimers with one and two disulfide bonds, and stopped flow analysis of tryptophan fluorescence, to investigate whether there is cooperativity between the sites.

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Rationale: Oxidative stress is an imbalance between reactive free radical oxygen species and antioxidant defenses. Its consequences can lead to numerous pathologies. Regulating oxidative stress is the complex interplay between antioxidant recycling and thiol-containing regulatory proteins.

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Using a unique data collection, we are able to study the detection of dense geometric objects in image data where object density, clarity, and size vary. The data is a large set of black and white images of scatterplots, taken from journals reporting thermophysical property data of metal systems, whose plot points are represented primarily by circles, triangles, and squares. We built a highly accurate single class U-Net convolutional neural network model to identify 97 % of image objects in a defined set of test images, locating the centers of the objects to within a few pixels of the correct locations.

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Hydrogen peroxide undergoes an equilibrium reaction with bicarbonate/CO to produce peroxymonocarbonate (HCO). Peroxymonocarbonate is more reactive with thiols than HO but it makes up only a small fraction of the HO in physiological bicarbonate buffers so the increase in rate of oxidation of low molecular weight thiols is modest. However, for some thiol proteins such as protein tyrosine phosphatases, the rate enhancement is very much greater.

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Fundamental limits for the calculation of scattering corrections within X-ray computed tomography (CT) are found within the independent atom approximation from an analysis of the cross sections, CT geometry, and the Nyquist sampling theorem, suggesting large reductions in computational time compared to existing methods. By modifying the scatter by less than 1 %, it is possible to treat some of the elastic scattering in the forward direction as inelastic to achieve a smoother elastic scattering distribution. We present an analysis showing that the number of samples required for the smoother distribution can be greatly reduced.

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Using a commercial X-ray tomography instrument, we have obtained reconstructions of a graded-index optical fiber with voxels of edge length 1.05 µm at 12 tube voltages. The fiber manufacturer created a graded index in the central region by varying the germanium concentration from a peak value in the center of the core to a very small value at the core-cladding boundary.

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Purpose: This paper lays the groundwork for linking Hounsfield unit measurements to the International System of Units (SI), ultimately enabling traceable measurements across X-ray CT (XCT) machines. We do this by characterizing a material basis that may be used in XCT reconstruction giving linear combinations of concentrations of chemical elements (in the SI units of mol/m3) which may be observed at each voxel. By implication, linear combinations not in the set are not observable.

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Hydrogen peroxide (HO) acts as a signaling molecule in cells by oxidising cysteine residues in regulatory proteins such as phosphatases, kinases and transcription factors. It is unclear exactly how many of these proteins are specifically targeted by HO because they appear too unreactive to be directly oxidised. One proposal is that peroxiredoxins (Prxs) initially react with HO and then oxidise adjacent proteins via a thiol relay mechanism.

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Peroxiredoxins are abundant peroxidase enzymes that are key regulators of the cellular redox environment. A major subgroup of these proteins, the typical 2-Cys peroxiredoxins, can switch between dimers and decameric or dodecameric rings, during the catalytic cycle. The necessity of this change in quaternary structure for function as a peroxidase is not fully understood.

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The goal of this study was to compare volumetric analysis in computed tomography (CT) with the length measurement prescribed by the Response Evaluation Criteria in Solid Tumors (RECIST) for a system with known mass and unknown shape. We injected 2 mL to 4 mL of water into vials of sodium polyacrylate and into disposable diapers. Volume measurements of the sodium polyacrylate powder were able to predict both mass and proportional changes in mass within a 95 % prediction interval of width 12 % and 16 %, respectively.

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