• Attack Transferability Against Information-Theoretic Feature Selection

      Gupta, S.; Golota, R.; Ditzler, G.; Department of Electrical & Computer Engineering, University of Arizona (Institute of Electrical and Electronics Engineers Inc., 2021)
      Machine learning (ML) is vital to many application-driven fields, such as image and signal classification, cyber-security, and health sciences. Unfortunately, many of these fields can easily have their training data tampered with by an adversary to thwart an ML algorithm’s objective. Further, the adversary can impact any stage in an ML pipeline (e.g., preprocessing, learning, and classification). Recent work has shown that many models can be attacked by poisoning the training data, and the impact of the poisoned data can be quite significant. Prior works on adversarial feature selection have shown that the attacks can damage feature selection (FS). Filter FS algorithms, a type of FS, are widely used for their ability to model nonlinear relationships, classifier independence and lower computational requirements. One important question from the security perspective of these widely used approaches is, whether filter FS algorithms are robust against other FS attacks. In this work, we focus on the task of information-theoretic filter FS such MIM, MIFS, and mRMR, and the impact that gradient-based attack can have on these selections. The experiments on five benchmark datasets demonstrate that the stability of different information-theoretic algorithms can be significantly degraded by injecting poisonous data into the training dataset. CCBY
    • Attaining quantum limited precision of localizing an object in passive imaging

      Sajjad, A.; Grace, M.R.; Zhuang, Q.; Guha, S.; James C. Wyant College of Optical Sciences, University of Arizona; Department of Electrical and Computer Engineering, University of Arizona (American Physical Society, 2021)
      We investigate our ability to determine the mean position, or centroid, of a linear array of equally bright incoherent point sources of light whose continuum limit is the problem of estimating the center of a uniformly radiating object. We consider two receivers, an image-plane ideal direct-detection imager and a receiver that employs Hermite-Gaussian (HG) spatial-mode demultiplexing in the image plane, prior to shot-noise-limited photon detection. We compare the Fisher information (FI) for estimating the centroid achieved by these two receivers, which quantifies the information-accrual rate per photon, and compare those with the quantum Fisher information (QFI): the maximum attainable FI by any choice of measurement on the collected light allowed by physics. We find that focal-plane direct imaging is strictly suboptimal, although not by a large margin. We also find that not only is the HG mode sorter, which is the optimal measurement for estimating the separation between point sources (or the length of a line object), suboptimal, but it performs worse than direct imaging. We study the scaling behavior of the QFI and direct imaging's FI for a continuous uniformly bright object in terms of its length and find that both are inversely proportional to the object's length when it is sufficiently larger than the Rayleigh length. Finally, we propose a two-stage adaptive modal receiver design that attains the QFI for centroid estimation. © 2021 American Physical Society.
    • Attaining the quantum limit of superresolution in imaging an object's length via predetection spatial-mode sorting

      Dutton, Zachary; Kerviche, Ronan; Ashok, Amit; Guha, Saikat; Univ Arizona, Coll Opt Sci (AMER PHYSICAL SOC, 2019-03-25)
      We consider estimating the length of an incoherently radiating quasimonochromatic extended object of length much smaller than the traditional diffraction limit, the Rayleigh length. This is the simplest abstraction of the problems of estimating the diameter of a star in astronomical imaging or the dimensions of a cellular feature in biological imaging. We find, as expected by the Rayleigh criterion, that the Fisher information (FI) of the object's length, per integrated photon, vanishes in the limit of small sub-Rayleigh length for an ideal image-plane direct-detection receiver. With an image-plane Hermite-Gaussian (HG) mode sorter followed by direct detection, we show that this normalized FI does not diminish with decreasing object length. The FI per photon of both detection strategies gradually decreases as the object length greatly exceeds the Rayleigh limit, due to the relative inefficiency of information provided by photons emanating from near the center of the object about its length. We evaluate the quantum Fisher information per unit integrated photon and find that the HG mode sorter exactly achieves this limit at all values of the object length. Further, a simple binary mode sorter maintains the advantage of the full mode sorter at highly sub-Rayleigh lengths. In addition to this FI analysis, we quantify improvement in terms of the actual mean-square error of the length estimate using predetection mode sorting. We consider the effect of imperfect mode sorting and show that the performance improvement over direct detection is robust over a range of sub-Rayleigh lengths.
    • An Attempt to Probe the Radio Jet Collimation Regions in NGC 4278, NGC 4374 (M84), and NGC 6166

      Ly, C.; Walker, R. C.; Wrobel, J. M.; Univ Arizona, Steward Observ (IOP Publishing, 2004-01)
      NRAO Very Long Baseline Array (VLBA) observations of NGC 4278, NGC 4374 (M84), NGC 6166, and M87 (NGC 4486) have been made at 43 GHz in an effort to image the jet collimation region. This is the first attempt to image the first three sources at 43 GHz using very long baseline interferometry (VLBI) techniques. These three sources were chosen because their estimated black hole mass and distance implied a Schwarzschild radius with large angular size, giving hope that the jet collimation regions could be studied. Phase referencing was utilized for the three sources because of their expected low flux densities. M87 was chosen as the calibrator for NGC 4374 because it satisfied the phase-referencing requirements: near the source and sufficiently strong. Having observed M87 for a long integration time, we have detected its subparsec jet, allowing us to confirm previous high-resolution observations made by Junor, Biretta, & Livio, who have indicated that a wide opening angle was seen near the base of the jet. Phase referencing successfully improved our image sensitivity, yielding detections and providing accurate positions for NGC 4278, NGC 4374, and NGC 6166. These sources are point dominated but show suggestions of extended structure in the direction of the large-scale jets. However, higher sensitivity will be required to study their subparsec jet structure.
    • Attenuated Activity across Multiple Cell Types and Reduced Monosynaptic Connectivity in the Aged Perirhinal Cortex

      Maurer, Andrew P.; Burke, Sara N.; Diba, Kamran; Barnes, Carol A.; Univ Arizona, Evelyn F McKnight Brain Inst; Univ Arizona, Div Neural Syst Memory & Aging; Univ Arizona, Dept Psychol; Univ Arizona, Dept Neurol; Univ Arizona, Dept Neurosci (SOC NEUROSCIENCE, 2017-09-13)
      The perirhinal cortex (PER), which is critical for associative memory and stimulus discrimination, has been described as a wall of inhibition between the neocortex and hippocampus. With advanced age, rats show deficits on PER-dependent behavioral tasks and fewer PER principal neurons are activated by stimuli, but the role of PER interneurons in these altered circuit properties in old age has not been characterized. In the present study, PER neurons were recorded while rats traversed a circular track bidirectionally in which the track was either empty or contained eight novel objects evenly spaced around the track. Putative interneurons were discriminated from principal cells based on the autocorrelogram, waveform parameters, and firing rate. While object modulation of interneuron firing was observed in both young and aged rats, PER interneurons recorded from old animals had lower firing rates compared with those from young animals. This difference could not be accounted for by differences in running speed, as the firing rates of PER interneurons did not show significant velocity modulation. Finally, in the aged rats, relative to young rats, there was a significant reduction in detected excitatory and inhibitory monosynaptic connections. Together these data suggest that with advanced age there may be reduced afferent drive from excitatory cells onto interneurons that may compromise the wall of inhibition between the hippocampus and cortex. This circuit dysfunction could erode the function of temporal lobe networks and ultimately contribute to cognitive aging.
    • Attenuated Late-Phase Arc Transcription in the Dentate Gyrus of Mice Lacking Egr3

      Maple, Amanda; Lackie, Rachel E.; Elizalde, Diana I.; Grella, Stephanie L.; Damphousse, Chelsey C.; Xa, Collin; Gallitano, Amelia L.; Marrone, Diano F.; Univ Arizona, Dept Basic Med Sci; Univ Arizona, McKnight Brain Inst; et al. (HINDAWI LTD, 2017)
      The dentate gyrus (DG) engages in sustained Arc transcription for at least 8 hours following behavioral induction, and this time course may be functionally coupled to the unique role of the DG in hippocampus-dependent learning and memory. The factors that regulate long-term DG Arc expression, however, remain poorly understood. Animals lacking Egr(3) show less Arc expression following convulsive stimulation, but the effect of Egr3 ablation on behaviorally induced Arc remains unknown. To address this, Egr3(-/-) and wild-type (WT) mice explored novel spatial environments and were sacrificed either immediately or after 5, 60, 240, or 480 minutes, and Arc expression was quantified by fluorescence in situ hybridization. Although short-term (i.e., within 60 min) Arc expression was equivalent across genotypes, DG Arc expression was selectively reduced at 240 and 480 minutes in mice lacking Egr3. These data demonstrate the involvement of Egr3 in regulating the late protein-dependent phase of Arc expression in the DG.
    • Attenuation of cGAS/STING activity during mitosis

      Uhlorn, Brittany L; Gamez, Eduardo R; Li, Shuaizhi; Campos, Samuel K; Univ Arizona, Canc Biol Grad Interdisciplinary Program; Univ Arizona, Dept Physiol; Univ Arizona, Dept Immunobiol; Univ Arizona, BIO5 Inst; Univ Arizona, Dept Mol & Cellular Biol (LIFE SCIENCE ALLIANCE LLC, 2020-07-13)
      The innate immune system recognizes cytosolic DNA associated with microbial infections and cellular stress via the cGAS/STING pathway, leading to activation of phospho-IRF3 and downstream IFN-I and senescence responses. To prevent hyperactivation, cGAS/ STING is presumed to be nonresponsive to chromosomal self-DNA during open mitosis, although specific regulatory mechanisms are lacking. Given a role for the Golgi in STING activation, we investigated the state of the cGAS/STING pathway in interphase cells with artificially vesiculated Golgi and in cells arrested in mitosis. We find that whereas cGAS activity is impaired through interaction with mitotic chromosomes, Golgi integrity has little effect on the enzyme's production of cGAMP. In contrast, STING activation in response to either foreign DNA (cGAS-dependent) or exogenous cGAMP is impaired by a vesiculated Golgi. Overall, our data suggest a secondary means for cells to limit potentially harmful cGAS/ STING responses during open mitosis via natural Golgi vesiculation.
    • Attenuation of the Type IV Pilus Retraction Motor Influences Neisseria gonorrhoeae Social and Infection Behavior

      Hockenberry, Alyson M.; Hutchens, Danielle M.; Agellon, Al; So, Magdalene; Univ Arizona, Dept Immunobiol; Univ Arizona, Inst BIO5; Univ Arizona, Sch Anim & Comparat Biomed Sci; Univ Arizona, Sch Publ Hlth (AMER SOC MICROBIOLOGY, 2016-12-06)
      Retraction of the type IV pilus (Tfp) mediates DNA uptake, motility, and social and infection behavior in a wide variety of prokaryotes. To date, investigations into Tfp retraction-dependent activities have used a mutant deleted of PilT, the ATPase motor protein that causes the pilus fiber to retract. Delta pilT cells are nontransformable, nonmotile, and cannot aggregate into microcolonies. We tested the hypothesis that these retraction-dependent activities are sensitive to the strength of PilT enzymatic activity by using the pathogen Neisseria gonorrhoeae as a model. We constructed an N. gonorrhoeae mutant with an amino acid substitution in the PilT Walker B box (a substitution of cysteine for leucine at position 201, encoded by PilT(L201C)). Purified PilT(L201C) forms a native hexamer, but mutant hexamers hydrolyze ATP at half the maximal rate. N. gonorrhoeae PilT(L201C) cells produce Tfp fibers, crawl at the same speed as the wild-type (wt) parent, and are equally transformable. However, the social behavior of PilT(L201C) cells is intermediate between the behaviors of wt and Delta pilT cells. The infection behavior of PilT(L201C) is also defective, due to its failure to activate the epidermal growth factor receptor (EGFR)-heparin-binding EGF-like growth factor (HB-EGF) pathway. Our study indicates that pilus retraction, per se, is not sufficient for N. gonorrhoeae micro-colony formation or infectivity; rather, these activities are sensitive to the strength of PilT enzymatic activity. We discuss the implications of these findings for Neisseria pathogenesis in the context of mechanobiology. IMPORTANCE Type IV pili are fibers expressed on the surface of many bacteria. Neisseria gonorrhoeae cells crawl, take up DNA, and communicate with each other and with human cells by retracting these fibers. Here, we show that an N. gonorrhoeae mutant expressing an enzymatically weakened type IV pilus retraction motor still crawls and takes up DNA normally. However, mutant cells exhibit abnormal social behavior, and they are less infective because they fail to activate the epidermal growth factor receptor. Our study shows that N. gonorrhoeae social and infection behaviors are sensitive to the strength of the retraction motor enzyme.
    • Attitudes, beliefs, and norms about sex and sexuality among young Indian male adults: A qualitative study

      Madhivanan, Purnima; Zohourian, Tirajeh; Hakim, Nader; Dorcius, PatriciaMoise; Shaheen, Reshma; Rao, IndiraRama; Carter, Rona; Krupp, Karl; Univ Arizona, Mel & Enid Zuckerman Coll Publ Hlth, Dept Hlth Promot Sci (WOLTERS KLUWER MEDKNOW, 2020)
      Objective: Little is known about the risky sexual behaviors, attitudes, beliefs, and sources of information regarding sexual health among young adult Indian males. Currently, students in Indian secondary schools do not receive a structured comprehensive sexual health education. This qualitative study explored the sources of information, knowledge, and attitudes around sexual behaviors among young men in Mysore, India. Materials and Methods: Between May and June 2011, 23 semi-structured qualitative in-depth interviews with males aged 18–25 years were conducted to explore their views on sexual norms, attitudes, and their sources of information to gain knowledge about sexual health. Interviews were audio recorded and transcribed verbatim. Thematic analyses were conducted. Results: Participants shared a desire for quality sex education in schools but described their current sexual health curriculum as inadequate. Since social taboos dictated the space in which students gained awareness on sexual topics, the participants resorted to the outside information from both reliable and unreliable sources. Conclusions: These findings have important implications for laying the groundwork for culturally specific sexual health education interventions to meet the needs of a growing youth population in India.
    • Attomicroscopy: attosecond electron microscopy

      Hassan, Mohammed; Univ Arizona, Dept Phys (SPIE-INT SOC OPTICAL ENGINEERING, 2018)
      The development of Ultrafast Electron Microscopy (UEM) and diffraction (UED) permit the imaging of atomic motion in real time and space. UEM and UED have found a vast range of applications spans chemistry, physics, material science, and biology. The temporal resolution in ultrafast electron imaging, typically on the order of few hundred femtoseconds, is limited by the electron pulse duration and the space charge effect. Hence, imaging the fast motions of electrons remains beyond the reach. Recently, we break the temporal resolution limits in UEM by generating a 30-fs electron pulse exploiting the optical gating approach. The gating technique is based on the electron-laser coupling where the free electrons in the wavepacket exchange energy with the light photons of the laser pulse. In this case, the optical laser pulse acts as a temporal gating for the electrons which gain/loss energy. These electrons are filtered out and generate an electron pulse with a temporal profile similar to the gating laser pulse. The obtained, few tens of femtosecond, temporal resolution opens the door-for the first time-to image the electron dynamics in real time. Moreover, the optical attosecond pulse, which has been demonstrated earlier, eventually will be used to gate the electrons in a sub-femtosecond time window. So, the gated electrons will generate a single isolated attosecond electron pulse. This unique tool will establish the attosecond electron imaging tool which we so-called "Attomicroscopy". Attomicroscopy will enable the imaging of the electron motion, last few hundreds of attosecond to few femtoseconds, in action.
    • Atypical CD4(+)/CD8(+) Lymphocytosis and Prolonged Pancytopenia Associated With Human Herpesvirus 6 Reactivation After Autologous Peripheral Blood Stem Cell Transplantation

      Russell, Samantha J; Duran, Juanita; Fuchs, Deborah; Yeager, Andrew M; Univ Arizona, Coll Med Tucson, Dept Med; Univ Arizona, Coll Med Tucson, Dept Pathol; Univ Arizona, Canc Ctr (CIG MEDIA GROUP, LP, 2019-08-01)
    • Atypical Flowers Can Be as Profitable as Typical Hummingbird Flowers

      Waser, Nickolas M.; CaraDonna, Paul J.; Price, Mary V.; Univ Arizona, Sch Nat Resources & Environm (UNIV CHICAGO PRESS, 2018-11)
      In western North America, hummingbirds can be observed systematically visiting flowers that lack the typical reddish color, tubular morphology, and dilute nectar of hummingbird flowers. Curious about this behavior, we asked whether these atypical flowers are energetically profitable for hummingbirds. Our field measurements of nectar content and hummingbird foraging speeds, taken over four decades at multiple localities, show that atypical flowers can be as profitable as typical ones and suggest that the profit can support 24-h metabolic requirements of the birds. Thus, atypical flowers may contribute to successful migration of hummingbirds, enhance their population densities, and allow them to occupy areas seemingly depauperate in suitable resources. These results illustrate what can be gained by attending to the unexpected.
    • Atypical Mg-poor Milky Way Field Stars with Globular Cluster Second-generation-like Chemical Patterns

      Fernández-Trincado, J. G.; Zamora, O.; García-Hernández, D. A.; Souto, Diogo; Dell’Agli, F.; Schiavon, R. P.; Geisler, D.; Tang, B.; Villanova, S.; Hasselquist, Sten; et al. (IOP PUBLISHING LTD, 2017-08-23)
      We report the peculiar chemical abundance patterns of 11 atypical Milky Way (MW) field red giant stars observed by the Apache Point Observatory Galactic Evolution Experiment (APOGEE). These atypical giants exhibit strong Al and N enhancements accompanied by C and Mg depletions, strikingly similar to those observed in the so-called second-generation (SG) stars of globular clusters (GCs). Remarkably, we find low Mg abundances ([Mg/Fe]. < 0.0) together with strong Al and N overabundances in the majority (5/7) of the metal-rich ([Fe/H] greater than or similar to-1.0) sample stars, which is at odds with actual observations of SG stars in Galactic GCs of similar metallicities. This chemical pattern is unique and unprecedented among MW stars, posing urgent questions about its origin. These atypical stars could be former SG stars of dissolved GCs formed with intrinsically lower abundances of Mg and enriched Al (subsequently self-polluted by massive AGB stars) or the result of exotic binary systems. We speculate that the stars Mg-deficiency as well as the orbital properties suggest that they could have an extragalactic origin. This discovery should guide future dedicated spectroscopic searches of atypical stellar chemical patterns in our Galaxy, a fundamental step forward to understanding the Galactic formation and evolution.
    • Atypical presentation of cerebellar posterior reversible encephalopathy syndrome in a patient with HIV

      Raya, Michael; Nasir, Imaad; Liu, Antonio; Univ Arizona, Banner Univ, Dept Neurol,Med Ctr (WILEY, 2020-01-11)
      This case report is meant to widen the scope of lesion locations in posterior reversible encephalopathy syndrome (PRES) to include the brainstem, frontal lobe, and basal ganglia in order to increase the diagnosis and treatment of PRES.
    • An Atypical Presentation of Raynaud's Disease

      Viswanath, Omar; Peck, Jacquelin; Gill, Jatinder S; Univ Arizona, Coll Med Phoenix, Dept Anesthesiol (KARGER, 2019)
      Objective: A 57-year-old female with a 33-year history of constant hand discoloration and paronychia had undergone multiple evaluations with a failure to find a diagnosis. She continues to undergo an evolving treatment regimen and diagnostic workup in an effort to find a long-eluded diagnosis. Clinical Presentation: She began to develop superficial ulcerations over the proximal phalanx of her fingers, often pruritic and erythematous, with pain and edema. Intervention: She has since been managed with nifedipine and sildenafil and intermittent stellate ganglion blocks. Conclusion: Despite still lacking a formal diagnosis, her constellation of symptoms is most likely the result of an atypical presentation of Raynaud's disease. (C) 2019 The Author(s) Published by S. Karger AG, Basel.
    • Audiovisual recording in the emergency department: Ethical and legal issues

      Iserson, Kenneth V; Allan, Nathan G; Geiderman, Joel M; Goett, Rebecca R; Univ Arizona, Dept Emergency Med (W B SAUNDERS CO-ELSEVIER INC, 2019-08-27)
      Emergency physicians, organizations and healthcare institutions should recognize the value to clinicians and patients of HIPAA-compliant audiovisual recording in emergency departments (ED). They should promote consistent specialty-wide policies that emphasize protecting patient privacy, particularly in patient-care areas, where patients and staff have a reasonable expectation of privacy and should generally not be recorded without their prospective consent. While recordings can help patients understand and recall vital parts of their ED experience and discharge instructions, using always-on recording devices should be regulated and restricted to areas in which patient care is not occurring. Healthcare institutions should provide HIPAA-compliant methods to securely store and transmit healthcare-sensitive recordings and establish protocols. Protocols should include both consent procedures their staff can use to record and publish (print or electronic) audiovisual images and appropriate disciplinary measures for staff that violate them. EDs and institutions should publicly post their rules governing ED recordings, including a ban on all surreptitious or unconsented recordings. However, local institutions may lack the ability to enforce these rules without multi-party consent statutes in those states (the majority) where it doesn't exist. Clinicians imaging patients in international settings should be guided by the same ethical norms as they are at their home institution. Copyright © 2019. Published by Elsevier Inc.
    • Audit market concentration, audit fees, and audit quality: A cross-country analysis of complex audit clients

      Gunn, Joshua L.; Kawada, Brett S.; Michas, Paul N.; Univ Arizona, Eller Coll Management (ELSEVIER SCIENCE INC, 2019-11-14)
      Regulators around the world are concerned about the potentially harmful effects of high audit market concentration on audit pricing and quality. However, results in the overall literature have failed to reach consensus on this issue. We contribute to this debate by arguing that the audit market is segmented and that concentration in the Big 4 segment of the market leads to higher audit pricing. Accordingly, our analyses use international data and focus on concentration within the Big 4 group of firms across countries. We find that audit fees are increasing in our concentration measure for clients where the barriers to entry by competing auditors are higher, as proxied by client size, international operations, and IFRS use. Finally, we find evidence that audit quality is decreasing in Big 4 market concentration for these types of engagements. This indicates a wealth transfer from shareholders to audit firms when auditor concentration is high because these complex clients are charged more, but receive audits that are of lower quality. (C) 2019 Elsevier Inc. All rights reserved.
    • Auditors’ Quantitative Materiality Judgments: Properties and Implications for Financial Reporting Reliability

      CHOUDHARY, PREETI; MERKLEY, KENNETH; SCHIPPER, KATHERINE; Univ Arizona (WILEY, 2019-08-12)
      We analyze data made available through the PCAOB (Public Company Accounting Oversight Board) to provide descriptive evidence on the properties of auditors' actual quantitative materiality judgments and the implications of those judgments for financial reporting. Auditors' quantitative materiality judgments do not appear to result simply from applying conventional rules of thumb (e.g., 5% of pretax income), but instead are associated with size-related financial statement outcomes (income, revenues, and assets), where the relative importance of the size-related outcomes varies with client characteristics such as financial performance. Using the distribution of actual materiality amounts reported by auditors to the PCAOB as part of the audit-inspection process, we construct a materiality-judgment measure that locates a specific materiality amount within a normal range that is both comparable across varying client characteristics and supported by guidance in audit firm internal policy manuals. We find that looser materiality (an amount closer to the high end of a normal materiality range) is associated with fewer audit hours and lower audit fees, supporting the construct validity of this measure. We also find that looser materiality is associated with lower amounts of proposed audit adjustments and, in extreme cases, with a greater incidence of restatements, highlighting the importance of auditor materiality assessments for financial reporting reliability.
    • Augmented design and analysis of computer experiments: a novel tolerance embedded global optimization approach applied to SWIR hyperspectral illumination design

      Keresztes, Janos C.; John Koshel, R.; D’huys, Karlien; De Ketelaere, Bart; Audenaert, Jan; Goos, Peter; Saeys, Wouter; Univ Arizona, Coll Opt Sci (OPTICAL SOC AMER, 2016-12-12)
      A novel meta-heuristic approach for minimizing nonlinear constrained problems is proposed, which offers tolerance information during the search for the global optimum. The method is based on the concept of design and analysis of computer experiments combined with a novel two phase design augmentation (DACEDA), which models the entire merit space using a Gaussian process, with iteratively increased resolution around the optimum. The algorithm is introduced through a series of cases studies with increasing complexity for optimizing uniformity of a short-wave infrared (SWIR) hyperspectral imaging (HSI) illumination system (IS). The method is first demonstrated for a two-dimensional problem consisting of the positioning of analytical isotropic point sources. The method is further applied to two-dimensional (2D) and five-dimensional (5D) SWIR HSI IS versions using close-and far-field measured source models applied within the non-sequential ray-tracing software FRED, including inherent stochastic noise. The proposed method is compared to other heuristic approaches such as simplex and simulated annealing (SA). It is shown that DACEDA converges towards a minimum with 1 % improvement compared to simplex and SA, and more importantly requiring only half the number of simulations. Finally, a concurrent tolerance analysis is done within DACEDA for to the five-dimensional case such that further simulations are not required. (C) 2016 Optical Society of America
    • Augmented reality navigation to assist retrograde peroneal access for the endovascular treatment of critical limb ischemia

      Lu, Weifeng; Wang, Lixin; Zhou, Wei; Fu, Weiguo; Univ Arizona, Dept Surg, Div Vasc Surg (ELSEVIER, 2019-11-18)
      Retrograde access is an alternative approach to endovascular intervention for critical limb ischemia but may be challenging in patients with poor below-knee vessel runoff. Here, we introduce an innovative technique based on an augmented reality navigation system to gain successful retrograde access to the peroneal artery of an 84-year-old woman with critical limb ischemia. Our result showed that this innovative technique had the potential advantage of influencing target vessel access selection with lower contrast material volume and radiation exposure compared with the conventional approach. More in-depth study is required to investigate the safety and efficacy of augmented reality-assisted vascular interventions.