Now showing items 12800-12819 of 13755

    • Time-resolved dual-comb measurement of number density and temperature in a laser-induced plasma

      Zhang, Yu; Lecaplain, Caroline; Weeks, Reagan R D; Yeak, Jeremy; Harilal, Sivanandan S; Phillips, Mark C; Jason Jones, R; Univ Arizona, Dept Phys; Univ Arizona, Coll Opt Sci (OPTICAL SOC AMER, 2019-07-15)
      We utilize time-resolved dual-comb spectroscopy to measure the temporal evolution of the population number densities and absorption excitation temperature of Fe in a laser-induced plasma. The spectra of three excited-state transitions of Fe around 533 nm are simultaneously measured at different time delays following laser ablation of a stainless steel sample. This Letter probes late-time behaviors of laser-induced ablation plumes during plasma cooling. The high spectral resolution and broad spectral coverage of the dual-comb technique, combined with the time-resolved measurement capability shown here, will aid in the characterization of laser induced plasmas, including species identification and molecule and particle formation that can occur at later times in the plasma evolution. (C) 2019 Optical Society of America
    • Time-resolved image polarimetry of TRAPPIST-1 during planetary transits

      Miles-Páez, P A; Zapatero Osorio, M R; Pallé, E; Metchev, S A; Univ Arizona, Steward Observ; Univ Arizona, Dept Astron (OXFORD UNIV PRESS, 2019-01-09)
      We obtained linear polarization photometry (J-band) and low-resolution spectroscopy (ZJ-bands) of TRAPPIST-1, which is a planetary system formed by an M8-type low-mass star and seven temperate, Earth-sized planets. The photopolarimetric monitoring campaign covered 6.5 h of continuous observations including one full transit of planet TRAPPIST-1d and partial transits of TRAPPIST-1b and e. The spectrophotometric data and the photometric light curve obtained over epochs with no planetary transits indicate that the low-mass star has very low level of linear polarization compatible with a null value. However, the ‘in transit’ observations reveal an enhanced linear polarization signal with peak values of p∗=0.1 per cent with a confidence level of 3σ, particularly for the full transit of TRAPPIST-1d, thus confirming that the atmosphere of the M8-type star is very likely dusty. Additional observations probing different atmospheric states of TRAPPIST-1 are needed to confirm our findings, as the polarimetric signals involved are low. If confirmed, polarization observations of transiting planetary systems with central ultracool dwarfs can become a powerful tool for the characterization of the atmospheres of the host dwarfs and the validation of transiting planet candidates that cannot be corroborated by any other method.
    • Time-resolved spectropolarimetric observations of polars WX LMi and BY Cam

      Tutar Özdarcan, D.; Smith, P. S.; Keskin, V.; Univ Arizona, Steward Observ (OXFORD UNIV PRESS, 2017-07)
      Time-series spectropolarimetric observations of polar WX LMi and asynchronous polar BY Cam are presented. Magnetic field properties, radial velocities and optical polarization are investigated via consecutive observations with good phase sampling during a single orbital cycle. Both systems are found to have a decentred dipole magnetic field configuration. One of the poles of WX LMi has a field strength of 49 MG, while the other pole may have possible field strengths of 69, 104 or 207 MG, depending on the harmonic numbers of the cyclotron humps observed in the circularly polarized spectrum. For BY Cam, a field strength of 168 MG is found for one of the poles, while field strengths of 70, 160 or 212 MG are possible for the other pole.
    • Time-Space Distanciation as a Decolonizing Framework for Psychology

      Schmitt, Harrison J.; Young, Isaac F.; Keefer, Lucas A.; Palitsky, Roman; Stewart, Sheridan A.; Goad, Alexis N.; Sullivan, Daniel; University of Arizona (SAGE Publications Ltd, 2021-03-22)
      Coloniality describes the way in which racialized conceptions of being, personhood, and morality inherent in colonial regimes are maintained long after the formal end of colonial enterprises. Central to coloniality has been the material and psychological colonization of space and time, largely by Western and industrialized nations. We propose the importance of understanding the coloniality of time and space through a historically grounded framework called time-space distanciation (TSD). This framework posits that via the global spread of capitalism through colonization, psychological understandings of time and space have been separated from one another, such that they are now normatively treated as distinct entities, each with their own abstract and quantifiable value. We discuss the construct and its centrality to coloniality, as well as the ways in which contemporary psychology has been complicit in proliferating the coloniality of psychologies of time and space. Finally, we discuss ways to employ the decolonial strategies of denaturalization, indigenization, and accompaniment in the context of future research on the psychology of time and space. TSD contributes to decolonial efforts by combatting the reification of hegemonic psychological constructs, showing how these constructs arise as a function of historical changes in understanding, experience, and use of time and space. © 2021 The Author(s).
    • Time-varying quasi-closed-phase analysis for accurate formant tracking in speech signals

      Gowda, Dhananjaya; Kadiri, Sudarsana Reddy; Story, Brad; Alku, Paavo; Univ Arizona (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2020)
      In this paper, we propose a new method for the accurate estimation and tracking of formants in speech signals using time-varying quasi-closed-phase (TVQCP) analysis. Conventional formant tracking methods typically adopt a two-stage estimateand-track strategy wherein an initial set of formant candidates are estimated using short-time analysis (e.g., 10-50 ms), followed by a tracking stage based on dynamic programming or a linear state-space model. One of the main disadvantages of these approaches is that the tracking stage, however good it may he, cannot improve upon the formant estimation accuracy of the first stage. The proposed TVQCP method provides a single-stage formant tracking that combines the estimation and tracking stages into one. TVQCP analysis combines three approaches to improve formant estimation and tracking: (1) it uses temporally weighted quasi-closed-phase analysis to derive closed-phase estimates of the vocal tract with reduced interference from the excitation source, (2) it increases the residual sparsity by using the L-1 optimization and (3) it uses time-varying linear prediction analysis over long time windows (e.g., 100-200 ms) to impose a continuity constraint on the vocal tract model and hence on the formant trajectories. Formant tracking experiments with a wide variety of synthetic and natural speech signals show that the proposed TVQCP method performs better than conventional and popular formant tracking tools, such as Wavesurfer and Praat (based on dynamic programming), the KARMA algorithm (based on Kalman filtering), and DeepFormants (based on deep neural networks trained in a supervised manner). Matlab scripts for the proposed method can be found at: https://github.com/njaygowda/ftrack
    • Timekeeping infrastructure for the Catalina Sky Survey

      Seaman, Robert L.; Gibbs, Alex; Univ Arizona, Lunar & Planetary Lab (SPIE-INT SOC OPTICAL ENGINEERING, 2018)
      Time domain science forms an increasing fraction of astronomical programs at many facilities. Synoptic and targeted observing modes of transient, varying, and moving sources rely on precise clocks to provide the underlying time tags. Often precision is mistaken for accuracy, or the precise time signals never reach the instrumentation in the first place. We will discuss issues of deploying a stable high-precision GNSS clock on a remote mountaintop, and of conveying the resulting time signals to a computer in a way that permits hardware timestamping of the camera shutter (or equivalent) rather than the arbitrary delays encountered with non-real-time data acquisition software. Strengths and limitations of the Network Time Protocol will be reviewed. Timekeeping infrastructure deployed for the Catalina Sky Survey will serve as an example.
    • Timescales of the Climate Record in the South Polar Ice Cap of Mars

      Becerra, Patricio; Sori, Michael M.; Thomas, Nicolas; Pommerol, Antoine; Simioni, Emanuele; Sutton, Sarah S.; Tulyakov, Stepan; Cremonese, Gabriele; Univ Arizona, Lunar & Planetary Lab (AMER GEOPHYSICAL UNION, 2019-07-05)
      The South Polar Layered Deposits (SPLD) are the largest water ice reservoirs on Mars. Their accumulation is believed to result from climate oscillations that drive the movement of ice and dust on the surface. The High-Resolution Imaging Science Experiment and the Colour and Stereo Surface Imaging System have imaged exposures of its internal structure in troughs and marginal scarps. Here we use the stereo imaging products of these instruments to extract stratigraphic profiles representative of various locations throughout the SPLD. Through wavelet and series-matching analyses of these profiles, we reveal periodicities in the stratigraphy that correlate to the orbital oscillations that drive climate change on Mars and that have been observed to force the accumulation of the north polar cap. We infer that the water ice and dust of the SPLD were deposited at variable rates of 0.13-0.39 mm/year, taking a minimum of 10-30 Myr to accumulate. Plain Language Summary The single location on Mars with the most water ice is in the southern polar ice cap, in the so-called South Polar Layered Deposits (SPLD). Changes in Martian climate through time affect the locations on Mars where ice is stable, and it is believed that these changes drove the accumulation of layers upon layers of ice and dust in the SPLD. The High-Resolution Imaging Science Experiment and the Colour and Stereo Surface Imaging System are satellite cameras that have photographed troughs and scarps within the SPLD to produce 3-D views of this layered internal structure. We analyzed this structure and found patterns in the layering related to variations of Mars' orbit and spin axis. These variations drive climate change on Mars, so our analysis confirms the connection between the SPLD and Mars' astronomical parameters. From this relationship, we inferred that the ice and dust of the SPLD took at least 10-30 Myr to accumulate.
    • The timing and magnitude of changes to Hortonian overland flow at the watershed scale during the post‐fire recovery process

      Liu, Tao; McGuire, Luke A.; Wei, Haiyan; Rengers, Francis K.; Gupta, Hoshin; Ji, Lin; Goodrich, David C.; Department of Geosciences, University of Arizona; Department of Hydrology and Atmospheric Sciences, University of Arizona (Wiley, 2021-05-27)
      Extreme hydrologic responses following wildfires can lead to floods and debris flows with costly economic and societal impacts. Process-based hydrologic and geomorphic models used to predict the downstream impacts of wildfire must account for temporal changes in hydrologic parameters related to the generation and subsequent routing of infiltration-excess overland flow across the landscape. However, we lack quantitative relationships showing how parameters change with time-since-burning, particularly at the watershed scale. To assess variations in best-fit hydrologic parameters with time, we used the KINEROS2 hydrological model to explore temporal changes in hillslope saturated hydraulic conductivity (Ksh) and channel hydraulic roughness (nc) following a wildfire in the upper Arroyo Seco watershed (41.5 km2), which burned during the 2009 Station fire in the San Gabriel Mountains, California, USA. This study explored runoff-producing storms between 2008 and 2014 to infer watershed hydraulic properties by calibrating the model to observations at the watershed outlet. Modelling indicates Ksh is lowest in the first year following the fire and then increases at an average rate of approximately 4.2 mm/h/year during the first 5 years of recovery. The estimated values for Ksh in the first year following the fire are similar to those obtained in previous studies on smaller watersheds (<1.5 km2) following the Station fire, suggesting hydrologic changes detected here can be applied to lower-order watersheds. Hydraulic roughness, nc, was lowest in the first year following the fire, but increased by a factor of 2 after 1 year of recovery. Post-fire observations suggest changes in nc are due to changes in grain roughness and vegetation in channels. These results provide quantitative constraints on the magnitude of fire-induced hydrologic changes following severe wildfires in chaparral-dominated ecosystems as well as the timing of hydrologic recovery. © 2021 John Wiley & Sons Ltd.
    • The Timing and Source of Long-Run Returns Following Repurchases

      Bargeron, Leonce; Bonaime, Alice; Thomas, Shawn; Univ Arizona, Eller Coll Management (CAMBRIDGE UNIV PRESS, 2017-04-21)
      This paper investigates the timing and source of anomalous positive long-run abnormal returns following repurchase authorizations. Returns between program authorization and completion announcements are indistinguishable from 0. Abnormal returns occur only after completion announcements. Long-run returns are largely attributable to announcement returns at subsequent authorizations and takeover attempts; that is, anomalous post-authorization returns are not persistent drifts but rather step functions. These findings have important implications for prior papers examining this most persistent and widespread anomaly. Further, our results serve to refocus the search for a rational explanation for the anomaly on subsequent repurchase announcements and takeover bids.
    • Timing of Resource Availability Drives Divergent Social Systems and Home Range Dynamics in Ecologically Similar Tree Squirrels

      Mazzamuto, Maria Vittoria; Merrick, Melissa J.; Bisi, Francesco; Koprowski, John L.; Wauters, Lucas; Martinoli, Adriano; Univ Arizona, Sch Nat Resources & Environm (FRONTIERS MEDIA SA, 2020-06-25)
      Intraspecific variation in home range size has important implications for the distribution of animals across landscapes and the spatial structuring of population, community, and ecosystem processes. Among species of similar trophic guild and body mass, differences in home range size can reflect extrinsic variables that exert divergent selective forces upon spacing behavior and social organization. We tested predictions about how resource availability and timing influence social system, home range size, and territoriality in two tree squirrel species of similar size and ecological niches but that differ in foraging strategy and social organization. We estimated home range size and intraspecific home range core overlap in the Mt. Graham red squirrel (Tamiasciurus fremonti grahamensis; Arizona USA; MGRS) and the Eurasian red squirrel (Sciurus vulgaris; Alps, Italy; ERS) as functions of species, sex, season, and individual's body mass. However, body mass did not explain differences found between the two species. We found MGRS home ranges being three times smaller with higher core area exclusivity compared to ERS in all seasons. In fact, territorial MGRS evolved in a system of brief resource pulses and are larder hoarders, whereas ERS experience prolonged resource availability and are non-territorial. Only male MGRSs increased their home range during the breeding season, reflecting interspecific differences in social organization and mating behavior. Male ERS home ranges always overlap with several females to enhance mating success although male and female MGRS maintain nearly exclusive territories throughout the year. Only during spring and summer do males temporarily leave their food-based territory to increase mating opportunities with neighboring estrus females. Home range comparisons between ecologically similar species emphasize the importance of divergent extrinsic factors in shaping variability in body size-home range size scaling relationships. Timing in resource availability influenced the social structure and space use in tree squirrels of similar body size, highlighting how the coevolution of arboreal squirrels with conifer tree species has shaped their natural history.
    • Timing the Early Assembly of the Milky Way with the H3 Survey

      Bonaca, Ana; Conroy, Charlie; Cargile, Phillip A.; Naidu, Rohan P.; Johnson, Benjamin D.; Zaritsky, Dennis; Ting, Yuan-Sen; Caldwell, Nelson; Han, Jiwon Jesse; van Dokkum, Pieter; et al. (IOP PUBLISHING LTD, 2020-07)
      The archeological record of stars in the Milky Way opens a uniquely detailed window into the early formation and assembly of galaxies. Here we use 11,000 main-sequence turn-off stars with well-measured ages, [Fe/H],[alpha/Fe], and orbits from the H3 Survey and Gaia to time the major events in the early Galaxy. Located beyond the Galactic plane, 1 less than or similar to vertical bar Z vertical bar/kpc less than or similar to 4, this sample contains three chemically distinct groups: a low-metallicity population, and low-alpha and high-alpha groups at higher metallicity. The age and orbit distributions of these populations show that (1) the high-alpha group, which includes both disk stars and the in situ halo, has a star formation history independent of eccentricity that abruptly truncated 8.3 +/- 0.1 Gyr ago (z similar or equal to 1); (2) the low-metallicity population, which we identify as the accreted stellar halo, is on eccentric orbits and its star formation truncated 10.2.(+0.2)(-0.1) Gyr ago (z similar or equal to 2); (3) the low-alpha population is primarily on low-eccentricity orbits and the bulk of its stars formed less than 8 Gyr ago. These results suggest a scenario in which the Milky Way accreted a satellite galaxy at z approximate to 2 that merged with the early disk by z approximate to 1. This merger truncated star formation in the early high-alpha disk and perturbed a fraction of that disk onto halo-like orbits. The merger enabled the formation of a chemically distinct, low-alpha disk at z less than or similar to 1. The lack of any stars on halo-like orbits at younger ages indicates that this event was the last significant disturbance to the Milky Way disk.
    • Tinnitus Correlates with Downregulation of Cortical Glutamate Decarboxylase 65 Expression But Not Auditory Cortical Map Reorganization

      Miyakawa, Asako; Wang, Weihua; Cho, Sung-Jin; Li, Delia; Yang, Sungchil; Bao, Shaowen; Univ Arizona, Dept Physiol (SOC NEUROSCIENCE, 2019-12-11)
      Hearing loss is the biggest risk factor for tinnitus, and hearing-loss-related pathological changes in the auditory pathway have been hypothesized as the mechanism underlying tinnitus. However, due to the comorbidity of tinnitus and hearing loss, it has been difficult to differentiate between neural correlates of tinnitus and consequences of hearing loss. In this study, we dissociated tinnitus and hearing loss in FVB mice, which exhibit robust resistance to tinnitus following monaural noise-induced hearing loss. Furthermore, knock-down of glutamate decarboxylase 65 (GAD65) expression in auditory cortex (AI) by RNA interference gave rise to tinnitus in normal-hearing FVB mice. We found that tinnitus was significantly correlated with downregulation of GAD65 in the AI. By contrast, cortical map distortions, which have been hypothesized as a mechanism underlying tinnitus, were correlated with hearing loss but not tinnitus. Our findings suggest new strategies for the rehabilitation of tinnitus and other phantom sensation, such as phantom pain.SIGNIFICANCE STATEMENT Hearing loss is the biggest risk factor for tinnitus in humans. Most animal models of tinnitus also exhibit comorbid hearing loss, making it difficult to dissociate the mechanisms underlying tinnitus from mere consequences of hearing loss. Here we show that, although both C57BL/6 and FVB mice exhibited similar noise-induced hearing threshold increase, only C57BL/6, but not FVB, mice developed tinnitus following noise exposure. Although both strains showed frequency map reorganization following noise-induced hearing loss, only C57BL/6 mice had reduced glutamate decarboxylase 65 (GAD65) expression in the auditory cortex (AI). Knocking down GAD65 expression in the AI resulted in tinnitus in normal-hearing FVB mice. Our results suggest that reduced inhibitory neuronal function, but not sensory map reorganization, underlies noise-induced tinnitus.
    • A Tip of the Red Giant Branch Distance to the Dark Matter Deficient Galaxy NGC 1052-DF4 from Deep Hubble Space Telescope Data

      Danieli, Shany; van Dokkum, Pieter; Abraham, Roberto; Conroy, Charlie; Dolphin, Andrew E.; Romanowsky, Aaron J.; Univ Arizona, Steward Observ (IOP PUBLISHING LTD, 2020-05-15)
      Previous studies have shown that the large, diffuse galaxies NGC 1052-DF2 and NGC 1052-DF4 both have populations of unusually luminous globular clusters as well as a very low dark matter content. Here we present newly obtained deep Hubble Space Telescope Advanced Camera for Surveys imaging of one of these galaxies, NGC 1052-DF4. We use these data to measure the distance of the galaxy from the location of the tip of the red giant branch (TRGB). We find a rapid increase in the number of detected stars fainter than m(F814W) similar to 27.3, which we identify as the onset of the red giant branch. Using a forward modeling approach that takes the photometric uncertainties into account, we find a TRGB magnitude of m(F814W,TRGB) = 27.47 +/- 0.16. The inferred distance, including the uncertainty in the absolute calibration, is D-TRGB = 20.0 +/- 1.6 Mpc. The TRGB distance of NGC 1052-DF4 is consistent with the previously determined surface brightness fluctuation distance of D-SBF = 18.7 +/- 1.7 Mpc to NGC 1052-DF2 and is consistent with the distance of the bright elliptical galaxy NGC 1052. We conclude that the unusual properties of these galaxies cannot be explained by distance errors.
    • "Tipping point" concept analysis in the family caregiving context

      Crist, Janice D; Liu, Jian; Shea, Kim D; Peterson, Rachel L; Martin-Plank, Lori; Lacasse, Cheryl L; May, Jennifer T; Wyles, Christina L; Williams, Deborah K; Slebodnik, Maribeth; et al. (WILEY, 2019-08-01)
      Aim Analyze the concept "tipping point" in the older adult family caregiving context to further knowledge about caregiving families, enhancing transdisciplinary theory, research, and practice. Background While used commonly in some disciplines, how "tipping point" has been used in health care, generally, and in relation to caregiving families, specifically, is less clear. This project was conducted to offer conceptual clarity to tipping point. Design Walker and Avant's framework. Data Source Searches of scholarly literature in PsycINFO, CINAHL, and PubMed using the search term "tipping point" in either title or abstract. Review Methods Definitions used were extracted; instances when the concept was implied but the actual term "tipping point" was not used and contexts where the term was used or implied were identified. Results The composite definition of a caregiving tipping point is a seemingly abrupt, severe, and absolute change event involving either the older adult or caregiver(s), or both that indicates a breakdown in the status quo of the caregiving system. Conclusions Transdisciplinary research, care, and policy should treat caregiving families as complex systems, use longitudinal assessments, and include colloquial communication. Early detection of impending tipping points will provide family-centered decisional support and enhance families' quality of life and safety.
    • TISMorph: A tool to quantify texture, irregularity and spreading of single cells

      Alizadeh, Elaheh; Xu, Wenlong; Castle, Jordan; Foss, Jacqueline; Prasad, Ashok; Univ Arizona, Dept Cellular & Mol Med (PUBLIC LIBRARY SCIENCE, 2019-06-03)
      A number of recent studies have shown that cell shape and cytoskeletal texture can be used as sensitive readouts of the physiological state of the cell. However, utilization of this information requires the development of quantitative measures that can describe relevant aspects of cell shape. In this paper we develop a toolbox, TISMorph, that calculates a set of quantitative measures to address this need. Some of the measures introduced here have been used previously, while others are new and have desirable properties for shape and texture quantification of cells. These measures, broadly classifiable into the categories of textural, irregularity and spreading measures, are tested by using them to discriminate between osteosarcoma cell lines treated with different cytoskeletal drugs. We find that even though specific classification tasks often rely on a few measures, these are not the same between all classification tasks, thus requiring the use of the entire suite of measures for classification and discrimination. We provide detailed descriptions of the measures, as well as the TISMorph package to implement them. Quantitative morphological measures that capture different aspects of cell morphology will help enhance large-scale image-based quantitative analysis, which is emerging as a new field of biological data.
    • Tissue ACE phenotyping in lung cancer

      Danilov, Sergei M; Metzger, Roman; Klieser, Eckhard; Sotlar, Karl; Trakht, Ilya N; Garcia, Joe G N; Univ Arizona Hlth Sci, Dept Med (PUBLIC LIBRARY SCIENCE, 2019-12-26)
      Background Pulmonary vascular endothelium is the main metabolic site for Angiotensin I-Converting Enzyme (ACE)-mediated degradation of several biologically-active peptides (angiotensin I, bradykinin, hemo-regulatory peptide Ac-SDKP). Primary lung cancer growth and lung cancer metastases decrease lung vascularity reflected by dramatic decreases in both lung and serum ACE activity. We performed precise ACE phenotyping in tissues from subjects with lung cancer. Methodology ACE phenotyping included: 1) ACE immunohistochemistry with specific and well-characterized monoclonal antibodies (mAbs) to ACE; 2) ACE activity measurement with two ACE substrates (HHL, ZPHL); 3) calculation of ACE substrates hydrolysis ratio (ZPHL/HHL ratio); 4) the pattern of mAbs binding to 17 different ACE epitopes to detect changes in ACE conformation induced by tumor growth (conformational ACE fingerprint). Results ACE immunostaining was dramatically decreased in lung cancer tissues confirmed by a 3-fold decrease in ACE activity. The conformational fingerprint of ACE from tumor lung tissues differed from normal lung (6/17 mAbs) and reflected primarily higher ACE sialylation. The increase in ZPHL/HHL ratio in lung cancer tissues was consistent with greater conformational changes of ACE. Limited analysis of the conformational ACE fingerprint in normal lung tissue and lung cancer tissue form the same patient suggested a remote effect of tumor tissue on ACE conformation and/or on "field cancerization" in a morphologically-normal lung tissues. Conclusions/Significance Local conformation of ACE is significantly altered in tumor lung tissues and may be detected by conformational fingerprinting of human ACE.
    • Tissue Augmentation with Allograft Adipose Matrix For the Diabetic Foot in Remission

      Shahin, Tala B.; Vaishnav, Kairavi V.; Watchman, Marcy; Subbian, Vignesh; Larson, Ethan; Chnari, Evangelia; Armstrong, David G.; Univ Arizona, Dept Biomed Engn (LIPPINCOTT WILLIAMS & WILKINS, 2017-10)
      Background: Repetitive stress on the neuropathic plantar foot is the primary cause of diabetic foot ulcers. After healing, recurrence is common. Modulating plantar pressure has been associated with extension of ulcer free days. Therefore, the goal of this study was to determine the effects of an injectable allograft adipose matrix in providing a protective padding and reducing the pressure in the plantar foot. Methods: After healing his recurrent ulcer using total contact casting, a 71-year-old man with a 9-year history of recurrent diabetic foot ulcers was treated with injection of allograft adipose matrix, procured from donated human tissue. This was delivered under postulcerative callus on the weight-bearing surface of the distal end of the first ray resection. As is standard in our clinic for tissue augmentation procedures, our patient underwent serial plantar pressure mapping using an in-shoe pressure monitoring system. Results: There was a 76.8% decrease in the mean peak pressure due to the fat matrix injected into the second metatarsal region and a 70.1% decrease in mean peak pressure for the first ray resection at the site of the postulcerative callus. By 2 months postoperatively, there was no evidence of residual callus. This extended out to the end of clinical follow-up at 4 months. Conclusion: The results from this preliminary experience suggest that allograft adipose matrix delivered to the high risk diabetic foot may have promise in reducing tissue stress over pre- and postulcerative lesions. This may ultimately assist the clinician in extending ulcer-free days for patients in diabetic foot remission.
    • Tissue Expanders and Proton Beam Radiotherapy

      Howarth, Ashley L.; Niska, Joshua R.; Brooks, Kenneth; Anand, Aman; Bues, Martin; Vargas, Carlos E.; Mahabir, Raman C.; Univ Arizona, Coll Med (LIPPINCOTT WILLIAMS & WILKINS, 2017-06)
      Proton beam radiotherapy (PBR) has gained acceptance for the treatment of breast cancer because of unique beam characteristics that allow superior dose distributions with optimal dose to the target and limited collateral damage to adjacent normal tissue, especially to the heart and lungs. To determine the compatibility of breast tissue expanders (TEs) with PBR, we evaluated the structural and dosimetric properties of 2 ex vivo models: 1 model with internal struts and another model without an internal structure. Although the struts appeared to have minimal impact, we found that the metal TE port alters PBR dynamics, which may increase proton beam range uncertainty. Therefore, submuscular TE placement may be preferable to subcutaneous TE placement to reduce the interaction of the TE and proton beam. This will reduce range uncertainty and allow for more ideal radiation dose distribution.
    • Tissue-resident macrophages can contain replication-competent virus in antiretroviral-naive, SIV-infected Asian macaques

      DiNapoli, Sarah R.; Ortiz, Alexandra M.; Wu, Fan; Matsuda, Kenta; Twigg, Homer L.; Hirsch, Vanessa M.; Knox, Kenneth; Brenchley, Jason M.; Univ Arizona, Dept Med (AMER SOC CLINICAL INVESTIGATION INC, 2017-02-23)
      SIV DNA can be detected in lymphoid tissue-resident macrophages of chronically SIV-infected Asian macaques. These macrophages also contain evidence of recently phagocytosed SIV-infected CD4(+) T cells. Here, we examine whether these macrophages contain replication-competent virus, whether viral DNA can be detected in tissue-resident macrophages from antiretroviral (ARV) therapy-treated animals and humans, and how the viral sequences amplified from macrophages and contemporaneous CD4(+) T cells compare. In ARV-naive animals, we find that lymphoid tissue-resident macrophages contain replication-competent virus if they also contain viral DNA in ARV-naive Asian macaques. The genetic sequence of the virus within these macrophages is similar to those within CD4(+) T cells from the same anatomic sites. In ARV-treated animals, we find that viral DNA can be amplified from lymphoid tissue-resident macrophages of SIV-infected Asian macaques that were treated with ARVs for at least 5 months, but we could not detect replicationcompetent virus from macrophages of animals treated with ARVs. Finally, we could not detect viral DNA in alveolar macrophages from HIV-infected individuals who received ARVs for 3 years and had undetectable viral loads. These data demonstrate that macrophages can contain replicationcompetent virus, but may not represent a significant reservoir for HIV in vivo.
    • Titan in transit: Ultraviolet stellar occultation observations reveal a complex atmospheric structure

      Tribbett, P.D.; Robinson, T.D.; Koskinen, T.T.; Lunar and Planetary Laboratory, University of Arizona (IOP Publishing, 2021)
      Transit spectroscopy is a key tool for exoplanet atmospheric characterization. However, transit spectrum observations can be limited by aerosol extinction when gas opacities are weak. The ultraviolet wavelength range contains a variety of strong molecular and atomic features, potentially enabling gas species detection even when atmospheric hazes are present. To understand the interplay between aerosol extinction and ultraviolet molecular opacities, we investigate transmission through the atmosphere of Saturn's moon Titan during an occultation observed with the Ultraviolet Imaging Spectrometer (UVIS) on board NASA's Cassini orbiter. We analyze the derived ultraviolet transit spectrum of Titan using exoplanet-relevant atmospheric retrieval models that both include and exclude treatments for hazes. Our retrieved gas column densities are consistent with previous studies analyzing UVIS occultation data. Despite the apparent haze impact on the underlying occultation data, our treatments fail to correctly characterize the haze in fits derived from simulated transit observations. This suggests that oversimplified haze parameterizations can hinder detection of atmospheric hazes in transit. Our work indicates that continued characterization of exoplanets in the ultraviolet wavelength regime can provide novel atmospheric constraints even if transit spectra are dominated by haze extinction at longer wavelengths. © 2021 The Author(s).