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The cosmic evolution of the chemical elements from the Big Bang to the present time is driven by nuclear fusion reactions inside stars and stellar explosions. A cycle of matter recurrently re-processes metal-enriched stellar ejecta into the next generation of stars. The study of cosmic nucleosynthesis and this matter cycle requires the understanding of the physics of nuclear reactions, of the conditions at which the nuclear reactions are activated inside the stars and stellar explosions, of the stellar ejection mechanisms through winds and explosions, and of the transport of the ejecta towards the next cycle, from hot plasma to cold, star-forming gas. Due to the long timescales of stellar evolution, and because of the infrequent occurrence of stellar explosions, observational studies are challenging, as they have biases in time and space as well as different sensitivities related to the various astronomical methods. Here, we describe in detail the astrophysical and nuclear-physical processes involved in creating two radioactive isotopes useful in such studies,
. Due to their radioactive lifetime of the order of a million years, these isotopes are suitable to characterise simultaneously the processes of nuclear fusion reactions and of interstellar transport. We describe and discuss the nuclear reactions involved in the production and destruction of
, the key characteristics of the stellar sites of their nucleosynthesis and their interstellar journey after ejection from the nucleosynthesis sites. This allows us to connect the theoretical astrophysical aspects to the variety of astronomical messengers presented here, from stardust and cosmic-ray composition measurements, through observation of
rays produced by radioactivity, to material deposited in deep-sea ocean crusts and to the inferred composition of the first solids that have formed in the Solar System. We show that considering measurements of the isotopic ratio of
eliminate some of the unknowns when interpreting astronomical results, and discuss the lessons learned from these two isotopes on cosmic chemical evolution. This review paper has emerged from an ISSI-BJ Team project in 2017–2019, bringing together nuclear physicists, astronomers, and astrophysicists in this inter-disciplinary discussion.
Evidence-based data on prevalence and risk factors of suicidal intentions and behavior in dementia are as scarce as the data on assisted dying. The present literature review aimed on summarizing the current knowledge and provides a critical discussion of the results.
A systematic narrative literature review was performed using Medline, Cochrane Library, EMBASE, PSYNDEX, PSYCINFO, Sowiport, and Social Sciences Citation Index literature.
Dementia as a whole does not appear to be a risk factor for suicide completion. Nonetheless some subgroups of patients with dementia apparently have an increased risk for suicidal behavior, such as patients with psychiatric comorbidities (particularly depression) and of younger age. Furthermore, a recent diagnosis of dementia, semantic dementia, and previous suicide attempts most probably elevate the risk for suicidal intentions and behavior. The impact of other potential risk factors, such as patient's cognitive impairment profile, behavioral disturbances, social isolation, or a biomarker based presymptomatic diagnosis has not yet been investigated. Assisted dying in dementia is rare but numbers seem to increase in regions where it is legally permitted.
Most studies that had investigated the prevalence and risk factors for suicide in dementia had significant methodological limitations. Large prospective studies need to be conducted in order to evaluate risk factors for suicide and assisted suicide in patients with dementia and persons with very early or presymptomatic diagnoses of dementia. In clinical practice, known risk factors for suicide should be assessed in a standardized way so that appropriate action can be taken when necessary.
This article looks at the first five years of reconstruction in Nagasaki City after the atomic bombing of 9 August 1945, elucidating how the municipal vision of reconstruction shaped the city's post-war urban identity, especially in comparison to Hiroshima. From early on, city officials envisioned the future of Nagasaki as a restored ‘international cultural city’, not solely as a centre of atomic memory, while Hiroshima made the atomic experience the centre of its urban identity. This article seeks to revive Nagasaki as a subject of historical inquiry in order to balance scholarly, as well as popular, literature on the bombings, which has favoured Hiroshima for nearly seven decades. In short, the story of Nagasaki sheds a different light on bombing and aftermath, not only in comparison with Hiroshima but with other cities that have suffered mass destruction and the course of their subsequent reconstruction.
Attention deficit hyperactivity disorder (ADHD) is one of the most common neurodevelopmental syndromes, with recent data suggesting prevalence rates in school-aged children between 8–10% (American Academy of Pediatrics & Subcommittee on Attention-Deficit/Hyperactivity Disorder, 2001; Barbaresi et al., 2002; Katusic et al., 2002; Leibson et al., 2001). Symptom onset is by the age of seven, with symptoms often evident between the ages of three to five years. The accurate diagnosis and effective treatment of ADHD in children can be critical to their academic, social, and interpersonal functioning. However, this is complicated by high rates of comorbid disorders in children with ADHD, including learning disabilities. The role of behavioral and neuropsychological assessment in diagnosis and treatment planning and effective treatment interventions will be discussed in this chapter. Furthermore, cognitive theories of ADHD and neuropsychological research, along with implications for clinical practice and future research will also be discussed.
The diagnosis of ADHD
ADHD is primarily characterized by two groups of core symptoms: (1) inattention and (2) hyperactive and impulsive behaviors. Currently, the DSM-IV-TR (APA, 2000) categorizes ADHD into three major subtypes: (1) Predominantly Inattentive Type (ADHD-I); (2) Predominantly Hyperactive/Impulsive Type (ADHD-H/I); and (3) Combined Type (ADHD-C), with the latter being the most common. Symptoms include short attention span, distractibility, forgetfulness, disorganization, restlessness, hyperactivity, impulsive responding and talkativeness. Overall, the male-to-female ratio for diagnosis is approximately 2:1 in community surveys (Cohen et al., 1999; Fergusson et al., 1993; Szatmari, Offord & Boyle, 1989).
Nuclear reactions occur in cosmic environments in the cores of stars and in
stellar explosions. Nuclear energy production is a key agent in these objects;
the production of new isotopes drives the chemical evolution of gas throughout
the universe and of the objects which form from this gas over cosmic times.
Radioactive isotopes, ejected into interstellar space by cosmic
nucleosynthesis events, are observed with new space telescopes.
Gamma-ray lines from the radioactive ejecta of such cosmic nuclear reactors
need to be sufficiently bright so they can be observed with current telescopes;
this limits all
gamma-ray astronomy studies to present and nearby nucleosynthesis
processes, i.e. out to few Mpc in distance and back a few million years in time.
The Compton Observatory had provided a first sky survey for the isotopes
56Co, 22Na, 44Ti, and 26Al, detecting supernova radioactivity
and the diffuse glow of long-lived radioactivity from massive stars in the Galaxy.
High-resolution spectroscopy is now being exploited with Ge detectors,
which allows to measure Doppler broadenings and line shape details
of these cosmic gamma-ray lines.
Current results include an all-sky map and line shape measurement of positron annihilation
emission, 26Al emission from the inner Galaxy and from the Cygnus region, a detection of
60Fe gamma-rays, and limits on 44Tiemission from Cas A
and other candidate young supernova remnants;
22Na from novae still has not been seen.
In this paper we discuss the experimental methods for such cosmic gamma-ray spectroscopy,
and the corresponding astrophysical implications.
The ESA observatory INTEGRAL (International Gamma-Ray Astrophysics Laboratory) is dedicated to fine imaging and spectroscopy in the energy range 15 keV to 10 Mev with concurrent X-ray (3-35 keV) and optical monitoring. It was launched on October 17, 2002 and has been succesfully operating ever since. Its two main instruments the spectrometer SPI – optimized for high resolution spectroscopy – and the imager IBIS – optimized for for high resolution imaging – are complemented by the X-ray monitor JEM-X and the optical monitor OMC. All the high energy instruments use coded mask techniques, allowing imaging in the gamma-ray range and combining wide fields of view with high spatial resolution. The presentation gives an overview of the unique properties of INTEGRAL.
Polarimetry in gamma-rays has the capability to enhance our understanding of compact object emission in our galaxy. In particular this diagnostic method could provide useful insight into the geometrical arrangement of these emitting objects and the roles that magnetic fields play in their emisson mechanisms. Gamma Ray Bursts have been studied in this way but the results, perhaps indicating a high degree of polarisation, remain unverified [Coburn & Boggs (2003), Wigger et al. (2004), Willis et al. (2005)]. The nature of GRBs solve many instrumental problems in polarimetry, however their true nature is less well defined and so a study of a better understood object such as the Crab Pulsar, for now, may reveal more as to the physics of the system.
InN continues to be a topic of great interest, particularly with respect to the issues surrounding its bandgap energy. To further explore this material and its properties, we have grown 200–300 nm InN films by a plasma-assisted molecular beam epitaxy (PAMBE) technique on a variety of substrates, including (0001) sapphire, (100) InAs, and both (100) and (111) YSZ. Single-crystal films regardless of quality all show the commonly reported broad luminescence feature in the range of 0.7 to 0.8 eV, although we have also observed this feature in polycrystalline films. Growth on (100) InAs and (100) YSZ was motivated by a desire to explore cubic InN; in both cases growth appears to be initially cubic, but a mixture of hexagonal and cubic phases is detected in the final layer.
In heavy ion fusion, the compression of the DT pellet requires
high intensity beams of ions in the gigaelectron volt energy
range. Charge-changing collisions due to intrabeam scattering
can have a high impact on the design of adequate accelerator
and storage rings. Not only do intensity losses have to be taken
into account, but also the deposition of energy on the beam
lines after bending magnets, for example, may be nonnegligible.
The center-of-mass energy for these intrabeam collisions is
typically in the kiloelectron volt range for beam energies in
the order of several gigaelectron volts. In this article, we
present experimental cross sections for charge transfer and
ionization in homonuclear collisions of Ar4+,
Kr4+, and Xe4+, and for charge transfer
only in homonuclear collisions of Pb4+ and
Bi4+. Using a hypothetical 100-Tm synchrotron as
an example, expected particle losses are calculated based on
the experimental data. The results are compared with expectations
for singly charged Bi+ ions, which are usually
considered for heavy ion fusion.
Hydrogen sulphide (H2S) is a common toxic air pollutant and is emitted from decomposing manure at animal facilities. However, there have been only a few studies of H2S emissions from animal buildings, especially those involving long-term, high-frequency measurements. In the current study, H2S emissions from two, 1000-head pig-finishing buildings in Illinois, USA, were monitored with a high-frequency measurement system for 6 months in 1997 during two, partial, pig-growth cycles. Air sample streams were continuously taken from the pit headspace, and the pit and wall fan exhaust air. Hydrogen sulphide concentration was measured at each location with H2S converters and sulphur dioxide (SO2) analysers during 16 or 24 sampling cycles per day, resulting in 4544 sampling cycles and 219 days of reliable data. Building ventilation rate was the summation of pit fan and wall fan airflow rates. Airflow rates of the underfloor manure pit fans were measured directly with full-size impeller anemometers or calculated from airflow/voltage relationships of the fans. Airflow rates of the wall fans were calculated from fan operation and differential static pressure data and fan performance curves. Mean H2S emission was 0·59 kg/day per building, 0·74 g/day per m2 of pit surface area, or 6·3 g/day per animal unit (AU = 500 kg animal weight). The determination of H2S emission per AU was restricted to 193 days when building occupancy was at least 700 pigs per building. Higher temperatures and building ventilation rates resulted in significantly higher H2S emissions per AU.
We have used thermal desorption spectroscopy to carry out a comparative study of potassium adsorption on Al(111) and on the fivefold Al-Pd-Mn surface. Potassium adsorption on the quasicrystal was found to be different than on Al(111). The potassium monolayer desorbed from fivefold Al-Pd-Mn at lower temperatures than from Al(111). Potassium is known to form a dense monolayer on Al(111), with an ideal coverage of 0.33, but for the monolayer on fivefold Al Pd Mn we find that the saturation coverage is only one twelfth.
The five-fold surface of the Al70 Pd21 Mn9 quasicrystal has been studied using STM, LEED and AES. STM images from surfaces which have been sputtered and annealed to 875 K reveal 20-30 Å protrusions that have been identified by others as Mackay-type clusters. Higher-resolution images reveal substructures in these clusters having dimensions 2-3 Å. Longer annealing times at 875 K produced large areas having flat terraces which were imaged with atomic resolution. The LEED pattern from this surface has sharp spots on a low background, and AES indicates that the surface is deficient in Mn relative to the bulk. For surfaces annealed to 1050 K for less than 2 hours, STM images indicate that cluster and terrace phases coexist, and a third phase having aligned arrays of clusters is identified which appears to be intermediate between the cluster and terrace phases.
We estimate the 1.8 MeV luminosity of the Sco-Cen association due to radioactive decay of 26A1 to (4 – 15) 10−5ph cm−2 s−1. We propose a low surface brightness, limb brightened bubble for the 1.8 MeV intensity distribution. The detectibility of this distribution with existing γ-ray telescopes is discussed.
26Al radioactivity is believed to originate predominantly from massive stars, ejected into interstellar medium in wind phases and/or supernova events. With its million-year decay time, penetrating γ-rays from 26Al decay measure the massive-star history averaged over a time scale of ≃million years, thus extending times cales accessible otherwise. The COMPTEL 1.809 MeV all-sky data from 5 years of observations show irregularities and features at intermediate latitudes, which may have a more local origin (≃ 1 kpc). We find that the large scale emission can be characterized by a Galactic scale height of ≃ 130 pc, and a Galactocentric scale radius of ≃ 5 kpc, with features from spiral structure. Catalogues from massive-star related objects do not significantly improve the description of COMPTEL data above this. Emission associated with nearby structures such as the Gould Belt, Loop I, or stellar aggregates, is indicated, yet cannot be clearly detected. Combined with our imaging results, this suggests that 26A1 yields from massive star ensembles depend on specifics of those stars and their history. Further 26A1 γ-ray studies are underway to help mapping of the massive star history in the solar vicinity.
The end of the cold war has signaled a dramatic increase in the number and forms of United Nations (UN) intervention into ongoing conflicts. Yet, this larger UN role has not always translated into success. Short-term failures are evident, but the long-term effects of UN efforts are not readily apparent. We explore this longer-term impact by examining the incidence of recurring conflict between state dyads following a crisis. Overall, UN intervention has proved ineffective in inhibiting, delaying, or lessening the severity of future conflicts, independent of the level of violence in the precipitating crisis, the relative capabilities of the two states, the states' history of conflict, and the form of crisis outcome; nor were UN efforts successful in deterring future conflict. These sobering results suggest that changes in long-term strategy may be in order.
The Compton Gamma-Ray Observatory (C-GRO) has completed a full-sky survey during which the number of known γ-ray pulsars has more than doubled. COMPTEL has observed the classical pulsars Crab and Vela on several occasions and has derived detailed pulse patterns and spectral parameters in the 0.7-30 MeV energy interval. The new C-GROγ-ray pulsars have different properties in terms of energy spectra and light-curve shapes, and, in fact, only the Crab is seen by all four C-GRO instruments. This raises intriguing questions about the particle acceleration processes and beaming taking place in the neutron magnetosphere. We have examined the COMPTEL data to add information on these objects in the 0.7-30 MeV energy interval and present evidence for the detection of one of them, PSR B1509-58. We have also undertaken a search for candidate radio pulsars whose ephemerides are well defined. The results of these analyses are presented.
Subject headings: gamma rays: observations — pulsars: general
MPE Compton Telescope observations of MeV radiation from the direction of the Galactic Center result in constraints on the central gamma-ray source in the Galaxy: The extent of 1.8 MeV line emission from 26Al suggests an 26Al production process with pronounced concentration towards the Galactic Center. The absence of other gamma-ray lines constrains nucleosynthesis and cosmic ray excitation parameters in the Galaxy. Calculations demonstrate that time variable Galactic Center annihilation radiation may be related to a central 26Al source.