Compact Optimization Learning for AC Optimal Power Flow

This paper reconsiders end-to-end learning approaches to the Optimal Power Flow (OPF). Existing methods, which learn the input/output mapping of the OPF, suffer from scalability issues due to the high dimensionality of the output space. This paper first shows that the space of optimal solutions can be significantly compressed using principal component analysis (PCA). It then proposes Compact Learning, a new method that learns in a subspace of the principal components before translating the vectors into the original output space. This compression reduces the number of trainable parameters substantially, improving scalability and effectiveness. Compact Learning is evaluated on a variety of test cases from the PGLib with up to 30,000 buses. The paper also shows that the output of Compact Learning can be used to warm-start an exact AC solver to restore feasibility, while bringing significant speed-ups.Comment: Submitted to IEEE Transactions on Power System

Using a Clinic-based Screening Tool for Primary Care Providers to Identify Commercially Sexually Exploited Children

Introduction: Commercial Sexual Exploitation of Children (CSEC), which encompasses acts of domestic minor sex trafficking, is a hidden problem in the U.S. that affects an estimated 300,000 children. Significant health impacts to victims include violence, substance abuse, mental illness, sexually transmitted diseases, and unintended pregnancy. However, due to the covert nature of sexual exploitation, the lack of understanding among service providers and law enforcement, and complex psychological factors experienced by victims, identifying CSEC is a tremendous challenge. Primary care providers can play a critical role in identifying CSEC victims within clinical settings to help address this silent epidemic. Objective: The goal of this project was to assess the prevalence of CSEC using a clinic-based screening tool within a community health center serving indigent populations, with a large proportion of the patients being of Asian and Pacific Islander descent. Methods: Medical charts were reviewed of young female patients (n=621) between 13-23 years of age and seeking clinical services in Asian Health Services’ Teen Clinic from 2008 through 2011, during the implementation of a clinic-based CSEC screening tool used by primary care providers. The CSEC screening tool consists of two questions about sexual exploitation. Results: Of the 621 patients in the study, 57.5% were Asian and Pacific Islander. Clinical providers applied the CSEC screening tool on 28.5% (n=177) of female patients in the study. Of the 177 patients who were screened, 7.3% (n=13) responded positive to questions about commercial sexual exploitation. Discussion: Using a clinic-based screening tool with patients who have identified risk factors helps primary care providers identify CSEC victims and link them to available resources. Under-reporting among victims and under-screening among providers remain major considerations in estimating CSEC prevalence. To address under-screening, it is important to raise awareness among primary care providers around the CSEC epidemic and their potential role for intervention, including screening for a history of sexual exploitation among youth patients

Mono-anionic phosphopeptides produced by unexpected histidine alkylation exhibit high plk1 polo-box domain-binding affinities and enhanced antiproliferative effects in hela cells

Binding of polo-like kinase 1 (Plk1) polo-box domains (PBDs) to phosphothreonine (pThr)/phosphoserine (pSer)-containing sequences is critical for the proper function of Plk1. Although high-affinity synthetic pThr-containing peptides provide starting points for developing PBD-directed inhibitors, to date the efficacy of such peptides in whole cell assays has been poor. This potentially reflects limited cell membrane permeability arising, in part, from the di-anionic nature of the phosphoryl group or its mimetics. In our current article we report the unanticipated on-resin N(τ)-alkylation of histidine residues already bearing a N(π)- alkyl group. This resulted in cationic imidazolium-containing pThr peptides, several of which exhibit single-digit nanomolar PBD-binding affinities in extracellular assays and improved antimitotic efficacies in intact cells. We enhanced the cellular efficacies of these peptides further by applying bio-reversible pivaloyloxymethyl (POM) phosphoryl protection. New structural insights presented in our current study, including the potential utility of intramolecular charge masking, may be useful for the further development of PBD-binding peptides and peptide mimetics.National Institutes of Health (U.S.) (Grants ES015339 and GM104047

Baseline Biomechanical Properties of Epithelia prior to Tissue Expansion in Dogs

Background: Soft-tissue deficiencies pose a challenge in a variety of disease processes when the end result is exposure of underlying tissue. Although multiple surgical techniques exist, the transposition of tissue from one location to another can cause donor-site morbidity, long incisions prone to dehiscence, and poor patient outcomes as a result. Use of tissue expansion prior to grafting procedures has been shown to have success in increasing available soft tissue to aid in repairing wounds. However, the current tissue expanders have biomechanical limits to the extent and rate of expansion that usually exceeds the tissue capacity, leading to incisional dehiscence or expander extrusion. Understanding the baseline biomechanical properties of the tissue to be expanded would provide useful information regarding surgical protocol employed for a given anatomical location. Therefore, the aim of this study was to test and compare the baseline (preexpansion) biomechanical properties of different common expansion sites in dogs. Methods: Four samples measuring approximately 20 × 15 × 1 mm were harvested from 8 dogs. The samples were collected from the hard palate, alveolar mucosa, scalp, and chest of the animal and analyzed for stress, strain, maximum tangential stiffness, maximum tangential modulus, and tensile strength using a Texture Technologies TA.XT texture analyzer with corresponding biomechanical measurement software. Samples were compared as to their baseline biomechanical properties prior to any soft-tissue expansion. Histological sections of the samples were analyzed using hematoxylin eosin in an attempt to correlate the histological description to the biomechanical properties seen during testing. Summary statistics (mean, standard deviation, standard error, range) are reported for stress, strain, maximum tangential stiffness, maximum tangential modulus, and tensile strength and for the histological parameters by intraoral site. Analysis of variance was used to compare the biomechanical and histological parameters among the 4 locations while accounting for multiple measurements from each dog. Results: The scalp had significantly higher maximum stress (σmax) than chest, mucosa, and palate (P 0.63). Scalp site also had significantly higher maximum tangential modulus (ε) than chest, mucosa, and palate (P 0.17). The locations did not have significantly different maximum tangential stiffness (k; P = 0.72). Histologically, 2 separate patterns of collagen disruption were evident. Conclusion: Although different results were obtained than theorized, this study showed that the scalp had the greatest resiliency to expand prior to tearing, and the highest tangential modulus, with all sites having statistically similar modulus of elasticity. Based on this study, the scalp could be expanded more aggressively compared with the other sites

Neighbor-directed histidine N (τ)-alkylation: A route to imidazolium-containing phosphopeptide macrocycles

Our recently discovered, selective, on-resin route to N(τ)-alkylated imidazolium-containing histidine residues affords new strategies for peptide mimetic design. In this, we demonstrate the use of this chemistry to prepare a series of macrocyclic phosphopeptides, in which imidazolium groups serve as ring-forming junctions. Interestingly, these cationic moieties subsequently serve to charge-mask the phosphoamino acid group that directed their formation. Neighbor-directed histidine N(τ)-alkylation opens the door to new families of phosphopeptidomimetics for use in a range of chemical biology contexts.National Institutes of Health (U.S.) (Grants ES015339 and GM104047

Human-Robot Site Survey and Sampling for Space Exploration

NASA is planning to send humans and robots back to the Moon before 2020. In order for extended missions to be productive, high quality maps of lunar terrain and resources are required. Although orbital images can provide much information, many features (local topography, resources, etc) will have to be characterized directly on the surface. To address this need, we are developing a system to perform site survey and sampling. The system includes multiple robots and humans operating in a variety of team configurations, coordinated via peer-to-peer human-robot interaction. In this paper, we present our system design and describe planned field tests

Smart SPHERES: A Telerobotic Free-Flyer for Intravehicular Activities in Space

Smart SPHERES is a prototype free-flying space robot based on the SPHERES platform. Smart SPHERES can be remotely operated by astronauts inside a spacecraft, or by mission controllers on the ground. We developed Smart SPHERES to perform a variety of intravehicular activities (IVA), such as operations inside the International Space Station (ISS). These IVA tasks include environmental monitoring surveys (radiation, sound levels, etc.), inventory, and mobile camera work. In this paper, we first discuss the motivation for free- flying space robots. We then describe the development of the Smart SPHERES prototype, including avionics, software, and data communications. Finally, we present results of initial flight tests on-board the ISS

Smart SPHERES: A Telerobotic Free-Flyer for Intravehicular Activities in Space

Smart SPHERES is a prototype free-flying space robot based on the SPHERES platform. Smart SPHERES can be remotely operated by astronauts inside a spacecraft, or by mission controllers on the ground. We developed Smart SPHERES to perform a variety of intravehicular activities (IVA), such as operations inside the International Space Station (ISS). These IVA tasks include environmental monitoring surveys (radiation, sound levels, etc.), inventory, and mobile camera work. In this paper, we first discuss the motivation for free-flying space robots. We then describe the development of the Smart SPHERES prototype, including avionics, software, and data communications. Finally, we present results of initial flight tests on-board the ISS