Erratum: "Inference of the Local Interstellar Spectra of Cosmic-Ray Nuclei Z ⩽ 28 with the GALPROP-HELMOD Framework" (2020, ApJS, 250, 27).

[This corrects the article PMC8549769.].

The Discovery of a Low-energy Excess in Cosmic-Ray Iron: Evidence of the Past Supernova Activity in the Local Bubble.

Since its launch, the Alpha Magnetic Spectrometer-02 (AMS-02) has delivered outstanding quality measurements of the spectra of cosmic-ray (CR) species ( p ¯ , e ±, and nuclei, 1H-8O, 10Ne, 12Mg, 14Si) which resulted in a number of breakthroughs. One of the latest long-awaited surprises is the spectrum of 26Fe just published by AMS-02. Because of the large fragmentation cross section and large ionization energy losses, most of CR iron at low energies is local and may harbor some features associated with relatively recent supernova (SN) activity in the solar neighborhood. Our analysis of the new AMS-02 results, together with Voyager 1 and ACE-CRIS data, reveals an unexpected bump in the iron spectrum and in the Fe/He, Fe/O, and Fe/Si ratios at 1-2 GV, while a similar feature in the spectra of He, O, and Si and in their ratios is absent, hinting at a local source of low-energy CRs. The found excess extends the recent discoveries of radioactive 60Fe deposits in terrestrial and lunar samples and in CRs. We provide an updated local interstellar spectrum (LIS) of iron in the energy range from 1 MeV nucleon-1 to ~10 TeV nucleon-1. Our calculations employ the GALPROP-HELMOD framework, which has proved to be a reliable tool in deriving the LIS of CR p ¯ , e -, and nuclei Z ⩽ 28.

Deciphering the Local Interstellar Spectra of Secondary Nuclei with the Galprop/Helmod Framework and a Hint for Primary Lithium in Cosmic Rays.

Local interstellar spectra (LIS) of secondary cosmic-ray (CR) nuclei, lithium, beryllium, boron, and partially secondary nitrogen, are derived in the rigidity range from 10 MV to ~200 TV using the most recent experimental results combined with state-of-the-art models for CR propagation in the Galaxy and in the heliosphere. The lithium spectrum appears somewhat flatter at high energies compared to other secondary species, which may imply a primary lithium component. Two propagation packages, GALPROP and HelMod, are combined to provide a single framework that is run to reproduce direct measurements of CR species at different modulation levels, and at both polarities of the solar magnetic field. An iterative maximum-likelihood method is developed that uses GALPROP-predicted LIS as input to HelMod, which provides the modulated spectra for specific time periods of the selected experiments for the model-data comparison. The proposed LIS accommodates the low-energy interstellar spectra measured by Voyager 1, the High Energy Astrophysics Observatory-3 (HEAO-3), and the Cosmic Ray Isotope Spectrometer on board of the Advanced Composition Explorer (ACE/CRIS), as well as the high-energy observations by the Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics (PAMELA), Alpha Magnetic Spectrometer-02 (AMS-02), and earlier experiments that are made deep in the heliosphere. The interstellar and heliospheric propagation parameters derived in this study are consistent with our earlier results for propagation of CR protons, helium, carbon, oxygen, antiprotons, and electrons.

Inference of the Local Interstellar Spectra of Cosmic-Ray Nuclei Z ⩽ 28 with the GalProp-HelMod Framework.

Composition and spectra of Galactic cosmic rays (CRs) are vital for studies of high-energy processes in a variety of environments and on different scales, for interpretation of γ-ray and microwave observations, for disentangling possible signatures of new phenomena, and for understanding of our local Galactic neighborhood. Since its launch, AMS-02 has delivered outstanding-quality measurements of the spectra of p ¯ , e ±, and nuclei: 1H-8O, 10Ne, 12Mg, 14Si. These measurements resulted in a number of breakthroughs; however, spectra of heavier nuclei and especially low-abundance nuclei are not expected until later in the mission. Meanwhile, a comparison of published AMS-02 results with earlier data from HEAO-3-C2 indicates that HEAO-3-C2 data may be affected by undocumented systematic errors. Utilizing such data to compensate for the lack of AMS-02 measurements could result in significant errors. In this paper we show that a fraction of HEAO-3-C2 data match available AMS-02 measurements quite well and can be used together with Voyager 1 and ACE-CRIS data to make predictions for the local interstellar spectra (LIS) of nuclei that are not yet released by AMS-02. We are also updating our already-published LIS to provide a complete set from 1H-28Ni in the energy range from 1 MeV nucleon-1 to ~100-500 TeV nucleon-1, thus covering 8-9 orders of magnitude in energy. Our calculations employ the GalProp-HelMod framework, which has proved to be a reliable tool in deriving the LIS of CR p ¯ , e -, and nuclei 1H-8O.

HelMod in the Works: From Direct Observations to the Local Interstellar Spectrum of Cosmic-Ray Electrons.

The local interstellar spectrum (LIS) of cosmic-ray (CR) electrons for the energy range 1 MeV to 1 TeV is derived using the most recent experimental results combined with the state-of-the-art models for CR propagation in the Galaxy and in the heliosphere. Two propagation packages, GALPROP and HelMod, are combined to provide a single framework that is run to reproduce direct measurements of CR species at different modulation levels, and at both polarities of the solar magnetic field. An iterative maximum-likelihood method is developed that uses GALPROP-predicted LIS as input to HelMod, which provides the modulated spectra for specific time periods of the selected experiments for model-data comparison. The optimized HelMod parameters are then used to adjust GALPROP parameters to predict a refined LIS with the procedure repeated subject to a convergence criterion. The parameter optimization uses an extensive data set of proton spectra from 1997 to 2015. The proposed CR electron LIS accommodates both the low-energy interstellar spectra measured by Voyager 1 as well as the high-energy observations by PAMELA and AMS-02 that are made deep in the heliosphere; it also accounts for Ulysses counting rate features measured out of the ecliptic plane. The interstellar and heliospheric propagation parameters derived in this study agree well with our earlier results for CR protons, helium nuclei, and anti-protons propagation and LIS obtained in the same framework.

Deciphering the Local Interstellar Spectra of Primary Cosmic-Ray Species with helmod.

Local interstellar spectra (LIS) of primary cosmic ray (CR) nuclei, such as helium, oxygen, and mostly primary carbon are derived for the rigidity range from 10 MV to ~200 TV using the most recent experimental results combined with the state-of-the-art models for CR propagation in the Galaxy and in the heliosphere. Two propagation packages, GALPROP and helmod, are combined into a single framework that is used to reproduce direct measurements of CR species at different modulation levels, and at both polarities of the solar magnetic field. The developed iterative maximum-likelihood method uses GALPROP-predicted LIS as input to helmod, which provides the modulated spectra for specific time periods of the selected experiments for model-data comparison. The interstellar and heliospheric propagation parameters derived in this study are consistent with our prior analyses using the same methodology for propagation of CR protons, helium, antiprotons, and electrons. The resulting LIS accommodate a variety of measurements made in the local interstellar space (Voyager 1) and deep inside the heliosphere at low (ACE/CRIS, HEAO-3) and high energies (PAMELA, AMS-02).

Solution of Heliospheric Propagation: Unveiling the Local Interstellar Spectra of Cosmic-ray Species.

Local interstellar spectra (LIS) for protons, helium, and antiprotons are built using the most recent experimental results combined with state-of-the-art models for propagation in the Galaxy and heliosphere. Two propagation packages, GALPROP and HelMod, are combined to provide a single framework that is run to reproduce direct measurements of cosmic-ray (CR) species at different modulation levels and at both polarities of the solar magnetic field. To do so in a self-consistent way, an iterative procedure was developed, where the GALPROP LIS output is fed into HelMod, providing modulated spectra for specific time periods of selected experiments to compare with the data; the HelMod parameter optimization is performed at this stage and looped back to adjust the LIS using the new GALPROP run. The parameters were tuned with the maximum likelihood procedure using an extensive data set of proton spectra from 1997 to 2015. The proposed LIS accommodate both the low-energy interstellar CR spectra measured by Voyager 1 and the high-energy observations by BESS, Pamela, AMS-01, and AMS-02 made from the balloons and near-Earth payloads; it also accounts for Ulysses counting rate features measured out of the ecliptic plane. The found solution is in a good agreement with proton, helium, and antiproton data by AMS-02, BESS, and PAMELA in the whole energy range.

Polyp and endoscopist-related factors influencing complication rates in difficult colonic polypectomies: results of a multicenter observational study.

BACKGROUND: Current polypectomy practices are highly variable. Endoscopists report increased size, nonpolypoid lesion type and unfavorable position as characteristic of difficult polypectomies. We studied reported difficult colonic polypectomies to determine polyp-related and operator-dependent factors influencing complication rates. PATIENTS AND METHODS: We conducted an international multicenter observational prospective study of difficult colonic polypectomies. Endoscopists reported difficult cases of colonic polypectomies, techniques and complication rates. Per-polyp and per-endoscopist analyses were performed. RESULTS: Ninety procedures were reported at 4 participating centers by 19 endoscopists. 43% of the lesions were pedunculated, 39% were sessile and 18% were flat. Lesion size ranged between 5-60 mm. Bleeding occurred in 18 out of 90 procedures (17 immediate, 1 delayed); no perforations were reported. Bleeding rate was independent of patient age or sex, polyp type, size and histology or resection method. Procedures were deemed difficult due to polyp size (37/90), unfavorable position (23/90), bleeding risk (12/90), lesion type (12/90) or other reasons (6/90) with no statistically significant difference between expert and beginner endoscopists (p = 0.14). CONCLUSION: Difficult colonic polypectomies are unpredictable with a complication rate independent of polyp type or size. There was no difference between experts and beginners with regard to technical aspects of resection or complication rates.

Direct and inverse reactions of LiH+ with He(1S) from quantum calculations: mechanisms and rates.

The gas-phase reaction of LiH(+) (X(2)Σ) with He((1)S) atoms, yielding Li(+)He with a small endothermicity for the rotovibrational ground state of the reagents, is analysed using the quantum reactive approach that employs the Negative Imaginary Potential (NIP) scheme discussed earlier in the literature. The dependence of low-T rates on the initial vibrational state of LiH(+) is analysed and the role of low-energy Feshbach resonances is also discussed. The inverse destruction reaction of LiHe(+), a markedly exothermic process, is also investigated and the rates are computed in the same range of temperatures. The possible roles of these reactions in early universe astrophysical networks, in He droplets environments or in cold traps are briefly discussed.

Computing charge-exchange cross sections for Ca+ collisions with Rb at low and ultralow energies.

Collisions between Ca cations and Rb atoms are computed within a quantum approach that generates the most relevant potential energy curves from accurate ab initio methods and carries out the low-energy scattering calculations by including nonadiabatic and spin-orbit coupling terms. The cross sections are obtained at relative energies typical for the likely arrangements of Rb atoms in a Magneto-Optical Trap overlapped with a Coulomb Crystal of Ca cations. The dominant nonadiabatic process is clearly identified and the efficiency of the nonadiabatic coupling terms which lead to the charge-exchange process is discussed.

Cold chemistry with ionic partners: quantum features of HeH+(1Σ) with H(1S) at ultralow energies.

Quantum reactive calculations are presented for an ion-atom reaction involving the HeH(+)cation and its destruction via a barrierless interaction with H atoms. The range of collision energies considered is that of a cold trap regime (around and below millikelvin) where the ionic partner could be spatially confined. Specific resonant features caused by the interplay of the strong ionic interaction with the very slow partners' dynamics are found and analyzed. Indications are also given on the consequences of the abstraction mechanism that acts for this reaction at low energies.

Translational cooling versus vibrational quenching in ultracold OH(-)-Rb collisions: a quantum assessment.

A new three-dimensional potential energy surface (PES), which describes the interaction between the OH(-)(X (1)Sigma(+)) anionic molecule and the Rb((2)S) atomic gas has been obtained by using a highly correlated ab initio model of the electronic structure and a large atomic basis set supplemented with a set of midbond Gaussian functions. This accurate PES is being employed to evaluate the OH(-)(X (1)Sigma(+)) vibrational quenching efficiency induced by collisions with Rb((2)S) at low and ultralow energies. Calculations employ the coupled-channel ansatz to describe the nuclear quantum dynamics and finally show a very marked dependence of the inelastic cross sections and rates, at vanishing collision energies, on the initial vibrational energy content of the partner molecules. The present findings allow us to make specific suggestions on the likely outcomes from energy interplay between the title species within a mixed MOT/Paul Trap environment.

Lipoxygenase activity during parabolic flights.

Experiments in Space clearly show that various cellular processes, such as growth rates, signaling pathways and gene expression, are modified when cells are placed under conditions of weightlessness. As yet, there is no coherent explanation for these observations, though recent experiments, showing that microtubule self-organization is gravity-dependent suggest that investigations at the molecular level might fill the gap between observation and understanding of Space effects. Lipoxygenases are a family of dioxygenases which have been implicated in the pathogenesis of several inflammatory conditions, in atherosclerosis, in brain aging and in HIV infection. In plants, lipoxy-genases favour germination, participate in the synthesis of traumatin and jasmonic acid and in the response to abiotic stress. Here, we took advantage of a fibre optics spectrometer developed on purpose, the EMEC (Effect of Microgravity on Enzymatic Catalysis) module, to measure the dioxygenation reaction by pure soybean lipoxygenase-1 (LOX-1) during the 28th parabolic flight campaign of the European Space Agency (ESA). The aim was to ascertain whether microgravity can affect enzyme catalysis.

Biochemical analysis of myelin lipids and proteins in a model of methyl donor pathway deficit: effect of S-adenosylmethionine.

S-Adenosylmethionine (SAMe) is the methyl donor to numerous acceptor molecules. We used cycloleucine (CL), which prevents the conversion of methionine to SAMe by inhibiting ATP-l-methionine-adenosyltransferase (MAT), to characterize the lipid and protein changes induced in peripheral nerve and brain myelin in rats during development. We also investigated the effect of exogenous SAMe by administering SAMe-1,4-butane disulfonate (SAMe-SD4). CL was given on days 7, 8, 12, and 13 and SAMe-SD4 was given daily from day 7; the animals were killed on day 18. CL accumulates in the brain reaching a concentration within 24 h compatible with its ID(50) in vitro and interacting with methionine metabolism; brain MAT activity and SAMe levels were lower and methionine levels higher than in controls. CL significantly reduced brain and nerve weight gains, brain myelin content, proteins, phospholipids, and galactolipids. Among phospholipids in nerve and brain, only sphingomyelin was significantly increased, by 35-50%. Sciatic nerve protein analyses showed some significant changes: protein zero in sciatic nerve remained unchanged but the 14.0- and 18.5-kDa isoforms of myelin basic protein showed a dramatic increase. Among the main proteins, in purified brain myelin, the proteolipid protein and dimer-20 isoform decreased after CL. SAMe-SD4 highlights some sensitive parameters by counteracting, at least partially, some alterations of PL--particularly galactolipids and sphingomyelins--and proteins induced by CL. The partial beneficial effects might also be explained by the age-related limited bioavailability of exogenous SAMe, a finding, to our knowledge, not yet reported elsewhere. This study demonstrates that availability of methyl donors is closely related to the formation of myelin components.

Enzyme kinetic parameters are not altered by microgravity.

This paper deals with a microgravity experiment concerning the EMEC project (Effect of Microgravity on Enzymatic Catalysis), performed during the parabolic flight of the sounding rocket MASER 7, launched from the base of Esrange (Kiruna, Sweden) on May 3, 1996. The experiment consisted of performing, in a microgravity environment, a number of velocity measurements of an enzyme (isocitrate lyase) catalyzed reaction at different substrate concentrations, to calculate the kinetic parameters (Km and Vmax), which were compared with those obtained at standard gravity, with identical instrumentation. The experimental hardware, the EMEC module, expressly set up by Officine Galileo (Firenze, Italy) with the financial support of the European Space Agency, was a multichannel fibre-optics radiometer, equipped with an automatic injection system, that allowed to measure simultaneously the transmittance changes in 16 reaction cells. The results indicated that under the experimental conditions applied, microgravity has no appreciable effect on the enzyme kinetic constants.

Use of a donor aortic cross for arterial reconstruction of the pancreaticoduodenal allograft.

Combined liver-pancreas procurement generally requires back bench reconstruction of the arterial blood supply with a donor Y-iliac graft to the pancreas graft. A modified vascular reconstruction that uses donor aortic cross including the brachiocephalic trunk and the left carotid artery as a single arterial patch is presented. This is useful when iliac grafts are unavailable or are being used as an alternative technique.

Neuronal death: is there a role for astrocytes?

Astrocytes are ubiquitous in the brain and have multiple functions. It is becoming increasingly clear that they play an important role in monitoring the neuromicroenvironment in CNS and in information processing or signaling in the nervous system in normal conditions and respond to CNS injuries in a gradual and varied way. It is still debated whether such reactions are beneficial or detrimental. It was believed that reactive astrogliosis observed in most neurological disorders may regulate the removal of toxic compounds produced by damaged neurons and support neuronal growth by releasing trophic factors. However it was also suggested that astrocytes contribute to a decline of neurologic function, for example by accumulation and release of excitotoxic aminoacids after ischemia and oxidative stress, formation of epileptogenic scars in response to CNS injury and metabolism of protoxins to potent toxins. In a number of metabolic diseases astrocytes, not neurons, may be the primary target. The astrocyte's role in normal and pathological conditions will be discussed in the light of recent information about their metabolism, receptor distribution and release.

ESS, eye stimulator system for VVIS facility (Visual and Vestibular Investigation System).

The ESS (Eye Stimulation System) is one of four main Subsystems of the Visual and Vestibular Investigation System ( VVIS ), Facility developed in the field of EDEN program and aimed to the research in the area of neurosensors physiology under microgravity conditions. In particular, the ESS is an Optokinetic Stimulator that stimulates the Subject's eyes with moving black and yellow patterns, in order to allow, by another main Subsystem, video recording of the pupil movement and, successively, to elaborate the relevant data of the neurovestibular experiment. This Stimulator was designed by the Officine Galileo as Subcontractor of Aerospatiale, leader of the VVIS facility, developed under ESA contract and successfully flown in April 1998 aboard the Neurolab mission. The Eye Stimulation System, on the frame of the VVIS Facility, is used in conjunction with the Body Rotating Device and the Eye Movement and Recording System, in order to fulfill all operations that lead to carry-out the experiments proposed. The Subject, seated on the Rotating Chair, observes the stimuli on a display monitor through a set of lenses, mounted on a proper box, fixed to a main structure of the unit. The stimuli patterns are showed on a display, placed on a movable support in order to fix it in a proper position, depending on the optical characteristics of the Subject. The experiments are repeated with different kind of patterns. All the main components of the visual system are mounted on a structural base plate, that gives also the mechanical I/F with the other system, supporting the ESS.