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Nuclear astrophysics, and particularly nuclear emission line diagnostics from a variety of cosmic sites, has remained one of the least developed fields in experimental astronomy, despite its central role in addressing a number of outstanding questions in modern astrophysics. Radioactive isotopes are co-produced with stable isotopes in the fusion reactions of nucleosynthesis in supernova explosions and other violent events, such as neutron star mergers. The origin of the 511 keV positron annihilation line observed in the direction of the Galactic Center is a 50-year-long mystery. In fact, we still do not understand whether its diffuse large-scale emission is entirely due to a population of discrete sources, which are unresolved with current poor angular resolution instruments at these energies, or whether dark matter annihilation could contribute to it. From the results obtained in the pioneering decades of this experimentally-challenging window, it has become clear that some of the most pressing issues in high-energy astrophysics and astro-particle physics would greatly benefit from significant progress in the observational capabilities in the keV-to-MeV energy band. Current instrumentation is in fact not sensitive enough to detect radioactive and annihilation lines from a wide variety of phenomena in our and nearby galaxies, let alone study the spatial distribution of their emission. In this White Paper (WP), we discuss how unprecedented studies in this field will become possible with a new low-energy gamma-ray space experiment, called ASTENA (Advanced Surveyor of Transient Events and Nuclear Astrophysics), which combines new imaging, spectroscopic and polarization capabilities. In a separate WP (Guidorzi et al. 39), we discuss how the same mission concept will enable new groundbreaking studies of the physics of Gamma–Ray Bursts and other high-energy transient phenomena over the next decades. [ABSTRACT FROM AUTHOR]

The INTernational Gamma-ray Astrophysics Laboratory (INTEGRAL) has detected the Short Gamma-Ray Burst (SGRB), GRB170817A with a signal-to-noise ratio of 4.6 and demonstrated its association with the binary neutron star merging event GW170817 detected by the LIGO and Virgo gravitational wave observatories. The association was immediately evident due to the timing and positional coincidence of this event with the initial error box, derived from gravitational wave (GW) measurements and the contemporaneous detection of a similar gamma-ray signal by Fermi/GBM. This SGRB was detected by the INTEGRAL SPI ACS about 1.7 s after the end of the GW emission, with a fluence of ( 1.4 ± 0.4 ) × 10 - 7 erg cm - 2 in the 75–2000 keV energy range. After the serendipitous detection of the short prompt GRB, INTEGRAL continued the planned observation for about 20 h, and then performed a targeted follow-up ToO observation lasting several days. This ToO observation provided a stringent upper limit on any electromagnetic signal in a very broad energy range, from 3 keV to 8 MeV, in particular constraining the soft gamma-ray afterglow flux to < 7.1 × - 11 erg cm - 2 s - 1 in the range 80–300 keV. Exploiting the unique capabilities of INTEGRAL, we constrained the gamma-ray line emission intensity from radioactive decays expected to be the principal source of the energy behind a kilonova event following a NS–NS coalescence. Finally, we put a stringent upper limit on any delayed bursting activity, for example, from a newly formed magnetar. The INTEGRAL prompt detection and the subsequent continuous observations at all wavelengths have provided important constraints on the high energy emission of the resulting kilonova and the post inspiral object: NS, BH, or a new exotic object. [ABSTRACT FROM AUTHOR]

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Particles are accelerated in cosmic sites probably under conditions very different from those at terrestrial particle accelerator laboratories. Nevertheless, specific experiments which explore plasma conditions and stimulate particle acceleration carry significant potential to illuminate some aspects of the cosmic particle acceleration process. Here we summarize our understanding of cosmic particle acceleration, as derived from observations of the properties of cosmic ray particles, and through astronomical signatures caused by these near their sources or throughout their journey in interstellar space. We discuss the candidate-source object variety, and what has been learned about their particle-acceleration characteristics. We conclude identifying open issues as they are discussed among astrophysicists. – The cosmic ray differential intensity spectrum across energies from 1010 eV to 1021 eV reveals a rather smooth power-law spectrum. Two kinks occur at the “knee” (≃1015 eV) and at the “ankle” (≃ 3×1018 eV). It is unclear if these kinks are related to boundaries between different dominating sources, or rather related to characteristics of cosmic-ray propagation. Currently we believe that galactic sources dominate up to 1017 eV or even above, and the extragalactic origin of cosmic rays at highest energies merges rather smoothly with galactic contributions throughout the 1015–1018 eV range. Pulsars and supernova remnants are among the prime candidates for galactic cosmic-ray production, while nuclei of active galaxies are considered best candidates to produce ultrahigh-energy cosmic rays of extragalactic origin. The acceleration processes are probably related to shocks formed when matter is ejected into surrounding space from energetic sources such as supernova explosions or matter accreting onto black holes. Details of shock acceleration are complex, as relativistic particles modify the structure of the shock, and simple approximations or perturbation calculations are unsatisfactory. This is where laboratory plasma experiments are expected to contribute, to enlighten the non-linear processes which occur under such conditions. [ABSTRACT FROM AUTHOR]

One of the scientific objectives of NASA’s Fermi Gamma-ray Space Telescope is the study of Gamma-Ray Bursts (GRBs). The Fermi Gamma-Ray Burst Monitor (GBM) was designed to detect and localize bursts for the Fermi mission. By means of an array of 12 NaI(Tl) (8 keV to 1 MeV) and two BGO (0.2 to 40 MeV) scintillation detectors, GBM extends the energy range (20 MeV to > 300 GeV) of Fermi’s main instrument, the Large Area Telescope, into the traditional range of current GRB databases. The physical detector response of the GBM instrument to GRBs is determined with the help of Monte Carlo simulations, which are supported and verified by on-ground individual detector calibration measurements. We present the principal instrument properties, which have been determined as a function of energy and angle, including the channel-energy relation, the energy resolution, the effective area and the spatial homogeneity. [ABSTRACT FROM AUTHOR]

The primary scientific goal of the GRIPS mission is to revolutionize our understanding of the early universe using γ-ray bursts. We propose a new generation gamma-ray observatory capable of unprecedented spectroscopy over a wide range of γ-ray energies (200 keV–50 MeV) and of polarimetry (200–1000 keV). The γ-ray sensitivity to nuclear absorption features enables the measurement of column densities as high as 1028cm − 2. Secondary goals achievable by this mission include direct measurements of all types of supernova interiors through γ-rays from radioactive decays, nuclear astrophysics with massive stars and novae, and studies of particle acceleration near compact stars, interstellar shocks, and clusters of galaxies. [ABSTRACT FROM AUTHOR]

Background. Impairment of cerebral autoregulation is known to adversely affect outcome following traumatic brain injury (TBI). The phase shift (PS) method of cerebral autoregulation (CA) assessment describes the time lag between fluctuations in arterial blood pressure (ABP) and cerebral blood flow velocity (CBFV) in the middle cerebral artery. An alternative method (Mx-ABP) is based on the statistical correlation between ABP and CBFV waveforms over time. We compared these two indices in a cohort of severely head injured patients undergoing controlled, 6-breaths-per-minute ventilation. Methods. PS and Mx-ABP were calculated from 33 recordings of CBFV and MAP in 22 patients with TBI. Spearman’s correlation coefficient was used to assess the agreement between PS and Mx-ABP. The relationship between ICP slow wave amplitude, MAP slow wave amplitude and mean ICP was also examined. Findings. Mean values for Mx-ABP and PS were 0.44 ± 0.27, and 49 ± 26 (degrees), respectively. PS correlated significantly with Mx-ABP ( r = −0.648, p < 0.001). A Bland-Altman plot of normalised Mx-ABP and Phase Shift values showed no significant bias or relationship (mean difference = 0.0004, r = −0.037, p = 0.852). During the test procedure, ICP fluctuated in an approximately sinusoidal fashion, with a mean amplitude of 4.96 ± 2.72 mmHg (peak to peak). The magnitude of ICP fluctuation during deep breathing correlated weakly but significantly with mean ICP ( r = 0.391, p < 0.05) and with the amplitude of ABP fluctuations ( r = 0.625, p < 0.0005). Conclusions. Phase shift and Mx-ABP in TBI are well correlated. Deep breathing presents as an effective tool with which to assess autoregulation using the phase shift method. [ABSTRACT FROM AUTHOR]

Background. As a sensitive and convenient means for the cerebral hemodynamic monitoring, dynamic cerebral autoregulation testing could be especially useful in medical conditions where less invasive diagnostics and therapies are preferred. This study analysed the effect of carotid stenting on dynamic autoregulation in elderly patients focussing on the relation between blood pressure and cerebral blood flow velocity. Methods. We examined 20 patients age 69 ± 8 years with coexisting cerebrovascular and medical risk factors before and at least six month after stenting of severe carotid stenoses. Data were compared to 24 age-matched healthy controls. Slow spontaneous oscillations were studied in continuous recordings of Transcranial Doppler and beat-to-beat blood pressure. Analysis was based on the “high-pass filter model”, which predicts a positive phase relationship between these oscillations. Findings. Whereas phase shift angles were diminished (20.4 ± 14.1°) before stenting, after stenting these values were significantly increased to normal (48.1 ± 16.6°), to the level of controls (46.7 ± 15.9°). Medical conditions such as coronary artery disease, arterial hypertension, and dyslipidemia did not diminish this recovery. The level of increase was inversely correlated with the initial autoregulatory deficit ( r = −0.68) which was largest with insufficient collateral blood supply and symptomatic carotid stenoses. Conclusions. The study showed that an impaired cerebral autoregulation may recover after stent-guided carotid angioplasty even in the elderly with co-existing medical conditions. In this respect to regain vasomotor capability, patients with cerebrovascular risk factors seemed to benefit particularly. [ABSTRACT FROM AUTHOR]

Originating from relativistic quantum field theory, Dirac fermions have been invoked recently to explain various peculiar phenomena in condensed-matter physics, including the novel quantum Hall effect in graphene, the magnetic-field-driven metal–insulator-like transition in graphite, superfluidity in 3He (ref. 5) and the exotic pseudogap phase of high-temperature superconductors. Despite their proposed key role in those systems, direct experimental evidence of Dirac fermions has been limited. Here, we report the first direct observation of relativistic Dirac fermions with linear dispersion near the Brillouin zone (BZ) corner H, which coexist with quasiparticles that have a parabolic dispersion near another BZ corner K. In addition, we also report a large electron pocket that we attribute to defect-induced localized states. Thus, graphite presents a system in which massless Dirac fermions, quasiparticles with finite effective mass and defect states all contribute to the low-energy electronic dynamics. [ABSTRACT FROM AUTHOR]

The main features of cosmic-ray source models and acceleration processes are reviewed, with special emphasis on the possible observational tests, through both composition analysis and multi-wavelength studies of supernova remnants. Non-linear effects in the context of supernova-induced diffusive shock acceleration are discussed, as well as collective acceleration effects induced by multiple supernova explosions inside superbubbles. [ABSTRACT FROM AUTHOR]

Observations of cosmic rays and their related radio to gamma-ray signatures are surveyed and discussed critically, and compared to theoretical models of the cosmic-ray origin and propagation. The analogous heliospheric processes are included as a well-studied case of the principal physical processes of energetic particle acceleration and propagation. Reinforcements, or conflicts, in the interpretations of cosmic-ray spectral and compositional characteristics arise when cosmic-ray source and propagation models are confronted with astronomical information about the Galaxy as a whole and from potential source sites, i.e., supernova remnants or regions with high massive-star density. This volume represents the outcome of two workshops held at ISSI. In this chapter we summarize the introductory papers presented below, and include insights from the workshop discussions. [ABSTRACT FROM AUTHOR]

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Standard autonomic tests (heart rate response to deep breathing-HR db, heart rate and systolic blood pressure response to tilt-ΔHR and ΔSBP) and spectral analysis of heart rate and arterial blood pressure and their transfer function (for the mid-frequency band a measure of baroreflex sensitivity) were performed in 20 patients with idiopathic Parkinson's disease (IPD) and 20 age-matched controls. Patients showed significantly diminished ΔSBP, and reduced sympathetic vasomotor and cardiomotor outflow (diminished Mayer waves), consistent with an alteration of the efferent arc of the baroreflex. These results were only significant in long-standing IPD (IPD-1, >5 years), whereas patients with short disease duration (IPD-s, <5 years) showed values comparable to controls. Respiratory-related heart rate variability was slightly reduced in IPD-1 but this was mainly due to diminished respiratory effort, indicated by low respiratoryrelated blood pressure variability. We conclude that autonomic abnormalities are only present in long-standing IPD and consist in reduced sympathetic vasomotor and cardiomotor outflow. [ABSTRACT FROM AUTHOR]

The measurement of heart rate variation during forced breathing (HRDB) is a well-known clinical test of parasympathetic function. It is known that normal values of HRDB are strongly dependent on age. However, little is known about other physiological factors that may lead to reduced HRDB values that may mimic parasympathetic failure. Thirty-two normal subjects (age 56.7±12.4 years) and 32 neurological patients with pathological autonomic test findings (age 57.9±10.2) were studied. Oscillations in heart rate and in mean arterial blood pressure were recorded in the supine position during forced breathing (6 cycles/min) using the Finapres monitor. Amplitudes of heart rate and blood pressure waves at 6 cycles/min (HR6 and ABP6) as well as gain values (Gain6=HR6/ABP6) and phase differences ({ie131-1}) between HR and ABP waves were calculated by means of spectral analysis. The mean (±SD) HR6 in normal subjects was 6.34±3.36 cycles/min with a mean ABP6 of 5.11±2.49 mmHg. HR6 correlated significantly with age ( r=−0.426) and with ABP6 ( r=0.602). No significant correlation was found between HR6 and mean blood pressure, mean heart rate or sex. From 24 patients with pathological findings in the classical HRDB value, only nine could be classified as pathological when the effect of ABP6 was considered. In conclusion, ABP variations significantly influence the amplitude of heart rate variations during forced breathing. We interpret these findings in terms of a baroreflex mechanism of HRDB including both vagal and sympathetic efferents. Normal reference value tables for clinical HRDB studies should not only consider age but also the amplitude of blood pressure variations. [ABSTRACT FROM AUTHOR]

The transmission of ions by channeling through natural beryl and synthetic emerald has been studied extensively. The transmission ratios depend upon the angle of incidence with a full half width of less than 0.32°. While the maximum ratio obtained up to now is only 4×10 for 350 keV protons through a crystal of 21 μm thickness, the energy of the transmitted ions is high, the loss being in the order of a few keV/μm. About 60-80% of the particles emerging from the rear surface are ionized. By varying the ion species transmission could be observed up to atomic number 9. It is assumed that the transmission is facilitated by the existence of an electron free channel core. Higher transmission ratios can be expected for sufficiently perfect crystals. [ABSTRACT FROM AUTHOR]

Copyright of Der Nervenarzt is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Presents research which discovered 44Ti line emission from a previously unknown young supernova remnant. Incomplete historical record of supernovae; Importance of gamma-ray emission related to the Cassiopeia A remnant; Distance, location, and age of the remnant; New remnant being the closest young remnant to Earth.

Presents a letter to the editor referencing articles and topics on cerebral ischemia related to cannabis smoking, published in previous issues.

A letter to the editor about a theory which states that the evolutionary target situation of vasovagal fainting was a life threatening bleeding is presented.