bluuebunny/crossref_metadata_2025 huggingface dataset:
Neurophysiology of Bipolar Disorder
Authors: Nery Fabiano G. , Fleck David E. , Tallman Maxwell J. , Adler Caleb M.
Published: May 2020

Functional magnetic resonance imaging (fMRI) and magnetic resonance spectroscopy (MRS) studies provide an exciting opportunity to understand the neural substrates that underlie the pathophysiology of bipolar disorder. This chapter reviews fMRI and MRS meta-analyses from the past 10 years to examine whether meta-analytic results differ from those otherwise expected on the basis of individual studies considered in isolation. Across different meta-analytic studies, and predominantly consistent with extant fMRI hypotheses, the most replicated findings are an overactivity of amygdala, especially during emotional processing, and underactivity of right ventrolateral prefrontal cortex during emotional or cognitive processing in bipolar disorder. These functional abnormalities appear to present during mania or depression, but not during euthymia, suggesting they are related to mood state, symptom severity, or both. Additionally, they appear to be rather specific to bipolar disorder, as opposed to major depressive disorder or schizophrenia. Recent prospective studies also suggest that clinical improvement associates with normalization of functional abnormalities or functional connectivity between prefrontal cortex and amygdala. MRS meta-analyses, although more limited than fMRI, suggest elevated glutamate in prefrontal cortex and decreased N-acetylaspartate in the basal ganglia and hippocampus. Additional studies employing multimodal imaging or longitudinal designs could help to advance the understanding of these neurofunctional and neurochemical brain abnormalities and to develop better preventive and therapeutic strategies for this condition.
A Programmatic Approach to Treatment
Authors: Strakowski Stephen M. , Almeida Jorge R. C.
Published: May 2020

Bipolar disorder is a complex, dynamic illness that affects mood, cognition, and psychosocial function across a wide range of behaviors. A myriad of symptoms wax and wane, causing distress and confusion. Functional recovery is often slow, and every recurrence creates setbacks that accumulate, potentially creating long-term disability. This complexity requires an integrated treatment approach that incorporates multiple modalities, from psychopharmacological to psychosocial, in order to maximally benefit individuals suffering from bipolar disorder. With a comprehensive care plan, most individuals with bipolar disorder will lead successful lives. An integrated practice unit specialized in treating bipolar disorder in the form of a 6-week cycle is discussed as one example of such an approach.
The International Classification of Functioning, Disability, and Health
Authors: Playford E. Diane
Published: May 2020

The International Classification of Functioning, Disability and Health (ICF) provides a framework for the description of health and health-related states and offers a biopsychosocial model of disability. The ICF was introduced by the World Health Organization in 1999 as a response to the conceptual and practical difficulties posed by its predecessor, the International Classification of Functioning, Disability and Health. The ICF lists body functions and structure, and activity and participation. The relationship between impairment, activity, and participation is not linear, and can be further moderated by contextual influences, including personal and environmental factors. There are a wide range of potential applications of the ICF. It has been adopted most widely within rehabilitation services to describe individual functioning, but can also be used at a service and national policy level to describe, monitor, and evaluate different activities. This chapter outlines the use of the ICF, considers its strengths, and highlights its function in a range of settings.
The applicability of motor learning to neurorehabilitation
Authors: Krakauer John W.
Published: May 2020

Rehabilitation is a form of directed training and is therefore predicated on the idea that patients respond to such training by learning. However, true recovery (restitution) with behavioural training is not synonymous with learning. Animal models suggest that there is a unique milieu of heightened plasticity post-stroke that is responsible for reduction in impairment both through spontaneous biological recovery and increased responsiveness to training. In the chronic phase of stroke, plasticity returns to normal levels with the goal mainly being task-specific compensation via normal motor learning mechanisms. In humans, there is a time-limited period of spontaneous recovery but it has yet to be shown whether patients after stroke have increased responsiveness to training over this same interval. Thus, new forms of behavioural intervention for patients may have distinct effects depending on whether they are initiated in the sensitive period after stroke (training interacting with repair) or in the chronic phase (compensation via motor learning). It is to be hoped that new pharmacological and non-invasive brain stimulation approaches will allow the post-stroke sensitive period to be augmented, extended, and re-opened. There may also be a subset of patients with chronic stroke that respond to much higher doses and intensities of motor training.
Functional recovery in CNS disease
Authors: Franz Steffen , Hug Andreas , Weidner Norbert
Published: May 2020

Animal models of central nervous system (CNS) diseases such as ischaemic stroke and spinal cord injury (SCI) are well suited for the analysis of tissue damage and functional impairment. Caveats with respect to preclinically observed spontaneous or elicited functional recovery, and the extrapolation into the clinical setting, are related to the animal species, respective disease models, the administration of the therapy under investigation, and the applied outcome measures in comparison to the clinical situation. SCI and ischaemic stroke share characteristics but differ in terms of therapeutic approaches. In ischaemic stroke innovative therapy concepts aim to protect CNS tissue at risk of degeneration, whereas in SCI efforts are made to regenerate damaged spinal cord tissue and to reinstall neuronal connectivity. This chapter examines components of animal models, the integration of clinical standard therapy concepts, the precise translation of experimental therapy administration, and the transferability of chosen structural and functional readouts in preclinical disease models of stroke and SCI.
Animal models of damage, repair, and plasticity in the brain
Authors: Luft Andreas R.
Published: May 2020

Recovery after a stroke is a multidimensional process depending on the individual deficit. Within each functional domain, spontaneous recovery occurs to a variable degree and can be improved by specific neurorehabilitative interventions. Basic knowledge about to the mechanisms of spontaneous and training-induced recovery is growing but translation to effective therapies has only been demonstrated in a few cases. Mechanistic knowledge is necessary to find new treatments that can fully exploit the brain’s capacity for recovery. Animal models can be an experimental platform to investigate these mechanisms. But it has to be realized that they oversimplify the human condition. The complexity of the interaction of motor, cognitive, social, emotional, and other factors contributing to recovery in humans cannot be modelled in animals. The opportunities and caveats of animal models are discussed.
Enhancement of neuroplasticity by cortical stimulation
Authors: Swayne Orlando B.C. , Rothwell John C.
Published: May 2020

Non-invasive brain stimulation methods such as transcranial magnetic stimulation and transcranial direct current stimulation allow us to interact directly with activity in neural circuits in the brain. Work has shown that these methods can also lead to changes in the effectiveness of synaptic connections, probably through mechanisms related to long-term potentiation/depression as described in animal preparations. Similar processes of synaptic plasticity are involved in many neurological rehabilitation techniques involve learning how to optimize performance in the face of neurological disease or injury. Thus combining non-invasive stimulation with rehabilitation may therefore be able to enhance plasticity and speed the response to therapy. We describe the techniques involved and summarize some of the recent clinical trials that have been conducted using this approach.
Enhancement of neuroplasticity by drug therapy
Authors: Ziemann Ulf
Published: May 2020

This chapter reviews effects of central nervous system (CNS) active drugs specifically on activity-dependent plasticity and learning. The rationale for choosing this focus is the existing evidence that CNS active drugs have an impact on rehabilitation success after stroke to a relevant extent only if coupled with task-specific practice. This chapter reviews pharmacological modulation of stimulation-induced long-term potentiation (LTP) in animal and human studies because synaptic plasticity in the form of LTP is a basic mechanism of learning and memory processes. Next, the chapter reviews the evidence of CNS active drugs on learning in animal and human studies. In the third part, the impact of CNS active drugs on neurorehabilitation of stroke patients is surveyed and the translational cascade from basic research to clinical studies is described. Finally, limitations of the current studies, open questions, and future directions are discussed. This chapter demonstrates significant impact of neuropharmacology on activity-dependent plasticity and learning.
Neurorehabilitation approaches for disorders of the peripheral nervous system
Authors: Huynh William , Lee Michael , Kiernan Matthew C.
Published: May 2020

Disorders of the peripheral nervous system comprise both traumatic and non-traumatic aetiologies that may involve different levels, from motor neurons in the spinal cord, emerging spinal nerve roots, brachial or lumbosacral plexus, to the peripheral nerves. Lesions can be focal, as in most cases of traumatic aetiology, or multifocal or generalized as commonly seen in non-traumatic causes. Current rehabilitative strategies aim at reversing the underlying cause of the nerve lesion, while at the same time, treating the symptoms and preventing complications that may arise as a consequence of the lesion. More specifically, the emphasis of rehabilitation is to maximize functional independence, locomotion, prevent physical deformity, facilitate integration into society, and overall, improve quality of life. The focus of this chapter is to provide a basic understanding regarding the pathophysiology of neurological deficits associated with lesions of the peripheral nervous system, followed by a systematic discussion of the general principles pertaining to neurorehabilitation of these patients. The aim is to provide the healthcare professional with a template and practical approach to the delivery of such therapy.
The clinical neurology of problems with oral feeding
Authors: Richards Tom , Hughes Tom
Published: May 2020

Oral feeding comprises a number of composite functions, all of which have to be coordinated to ensure adequate nutrition and hydration. Voluntary swallowing is central to the process, but without preserved pulmonary function, including cough, the airway is vulnerable. Medical and surgical problems, and the environment in which the patient is nursed, also determine the success of attempted oral feeding. Using this framework of thinking may help structure the clinical approach to oral feeding failure and facilitate discussion of issues other than just swallowing and dysphagia when forming opinions about the diagnosis and prognosis of the underlying disease, the mechanism of the feeding problem, and the most appropriate therapy. The goals of any intervention should be informed by a detailed appreciation of clinical issues and a working knowledge of the relevant ethical and legal issues. The MEALTIME approach is suggested as an aide memoire to help ensure that the relevant issues are addressed.
Promises and challenges of neurorehabilitation technology
Authors: Jayaraman Arun , Burt Sheila , Rymer William Z.
Published: May 2020

An increasing number of technologies are being used in rehabilitation hospitals and clinics to help therapists and physicians improve recovery of upper or lower extremity function in patients who have sustained a severe neurological injury. These technologies include robotic devices such as exoskeletons, electrical stimulation systems, wearable sensors, and virtual reality training systems. While various types of robotic devices will likely continue to be developed for therapeutic purposes at rapid speed as technology improves, there has been limited systematic collection of higher levels of evidence for everyday clinical practice. This chapter examines some of the reasons for the limited collection of evidence thus far, and offers potential reasons why technological approaches have not been more successful in the clinical application of these systems. A brief discussion on some advances in robotics and rehabilitation science research is also presented. Finally, the chapter explores ways in which some of the observed performance limitations can be circumvented, leading potentially to more effective therapies in the near future.
Diabetic retinopathy: reasons for screening
Authors: Galsworthy Paul
Published: May 2020

Diabetic retinopathy (DR) is still the most common form of eye disease for people with diabetes, but is no longer the leading cause of blindness in the working-age population. Patients with visual loss caused by DR is often as a result of late presentation to screening services, poor or non-attendance of diabetes care, and/or hospital eye services. Diabetes care is accountable for 10% of the NHS budget—most of this money is spent on inpatient care, rather than on prevention. DR meets the screening criteria of Wilson and Jungner for a successful programme, as it has important adverse effects, laser and intravitreal treatment is effective, it can be easily detected by digital imaging, which is an acceptable test, and is cost effective.
Diabetes and the eye
Authors: Dodson Paul M.
Published: May 2020

Diabetes mellitus is still one of the commonest causes of blindness worldwide. The ophthalmic complications of diabetes include diabetic retinopathy (DR), cataracts, primary open angle and neovascular glaucoma, and cranial nerve palsies. Retinovascular disease, including retinal vein and artery occlusion, and non-arteritic ischaemic optic neuropathy are more common in diabetic subjects. DR occurs in approximately 30–35% of diabetic subjects with ethnic differences. The primary abnormalities of DR are capillary basement membrane thickening, such that it becomes porous, and capillary occlusion with resultant retinal ischaemia. In Type 1 diabetes, DR is almost invariable after 15 years of disease duration. In Type 2 diabetes, 20% have retinal signs at diagnosis of diabetes, rising to a prevalence of 60% after 15 years of known disease duration. Major modifiable risk factors for DR include poor glucose and blood pressure control, and increasing lipid levels. In broad terms, Type 1 diabetes is associated with proliferative retinopathy, and Type 2 diabetes with maculopathy.
Maculopathy
Authors: Wharton Helen
Published: May 2020

This chapter examines the physiological changes within the macula that can lead to diabetic macular oedema (DMO), how these are detected at diabetic eye screening (DES), and the consequences this has on patient management. It looks at how the area of the macula is defined on the fundus image and the different surrogate markers used during screening to predict the presence of DMO. The grading criteria for maculopathy (M1) as defined by the NHS Diabetic Eye screening Programme (NHSDESP) are described, which includes single exudates, groups of exudates, and haemorrhages and microaneurysms with reduced visual acuity (VA). It examines the classification of different maculopathies, such as exudative (focal and diffuse), cystoid, and ischaemic, and includes images of their appearance on retinal images. Management of patients with maculopathy, such as referral to the hospital eye service (HES) or digital surveillance (DS) clinics, and treatment of DMO, including laser and intravitreal injections are also briefly mentioned.
Pre-proliferative and proliferative retinopathy
Authors: Amrelia Prashant
Published: May 2020

Pre-proliferative retinopathy precedes proliferative retinopathy (new vessel growth) and, therefore, is an indication that the eye will soon be leading on to the advanced stages of retinopathy. Pre-proliferative retinopathy indicates chronic retinal ischaemia due to blocked capillaries. The clinical signs include multiple deep round blot haemorrhages, intra-retinal microvascular abnormalities (IRMA), and venous beading/or venous reduplication. New vessels arise at the optic disc (NVD) or new vessels elsewhere (NVE) on the retinal surface due to retinal ischaemia and increase vascular endothelial growth factor (VEGF), and others. The new vessels help compensate the hypoxic (oxygen-starved) tissue. These new vessels can easily rupture leading to haemorrhage (vitreous haemorrhage) and severe visual loss.
Other ophthalmic lesions in the fundus
Authors: Gibson Jonathan M.
Published: May 2020

When screening the diabetic population for diabetic retinopathy (DR), many other retinal conditions can be identified, which may represent harmless variations of normality or serious ophthalmic pathology. The most important conditions that may be detected are retinal vein and artery occlusion, hypertensive retinopathy, arterial emboli, and retinal changes due to blood disorders, for example, anaemia. These conditions need local protocols for management, which are best obtained by input and advice from the relevant medical teams. Overall, familiarity with fundal appearance and pattern recognition are important in order to recognize common abnormalities, for example, drusen, chorioretinitis, asteroides hyalosis, choroidal naevi, and age-related macular degeneration.
Respecting Personal Autonomy in Bioethics
Authors: Childress James F.
Published: May 2020

This chapter unpacks the dominant, though thin and procedural, conception of the principle of respect for personal autonomy in the context of a medical and legal decision to allow a fourteen-year-old Jehovah’s Witness boy to refuse a blood transfusion needed to extend his life. It argues that thicker conceptions of autonomy, closely connected with relational autonomy, can enable us to see more clearly aspects of respect for autonomy too often neglected or downplayed. These help us understand better the interpretive complexity of this principle by directing attention beyond a potential beneficiary’s immediate decision in the moment to the broader context of relations that in part shape such decisions and to the temporal extensions of the self. As valuable as these indicators are, they should not be converted into necessary conditions of autonomous choices and actions for which respect is due. This would set the bar too high for autonomy, and it would deprive ordinary decision-makers of the protection and support needed for their autonomous choices and actions.
Religion, Morality, and Public Policy
Authors: Childress James F.
Published: May 2020

This chapter explores how religious convictions have functioned in the debate about whether human reproductive cloning should be banned, regulated, or permitted—a debate that erupted in 1997 following the belated announcement of “Dolly’s” birth. This historical case study examines and assesses the arguments that arose at the time, particularly in the context of the National Bioethics Advisory Commission (NBAC) report Cloning Human Beings. The NBAC hearings included testimony on religious views on human reproductive cloning, and its report examined and assessed those views. The chapter also considers NBAC’s deliberations about federal funding of human embryonic stem cell research that further illuminates the place of religious convictions in public bioethics. It concludes that in public bioethics the process of reaching a decision—or, in NBAC’s case, a recommendation—should attend to the widest possible range of positions and rationales, but that the outcome in substance and in public justification needs to involve, as Robert Audi argues, a sufficient or adequate secular reason.
Conscientious Refusals in Healthcare
Authors: Childress James F.
Published: May 2020

This chapter focuses not on the ethics of individual conscientious refusals but rather on ethically justified responses of institutions, organizations, and governments to such refusals. It asks under what conditions, if any, the state, society, institutions, and professions should exempt conscientiously objecting healthcare professionals from performing procedures or providing services or products that they find objectionable but that are legal and patient-sought. Using several cases and drawing several distinctions (e.g., religious and/or moral objections, and universal and selective objections), this chapter employs the metaphor of constrained balancing to develop a framework for accommodating many conscientious refusals, as distinguished from conscientious obstructions. At a minimum, this balance requires disclosure of information about options in all cases and referral/transfer of patients in certain cases. This chapter also identifies ways to resolve ongoing debates about expansive claims of complicity or unacceptable participation in wrongdoing sometimes invoked by conscientious objectors.
Putting Patients First in Organ Allocation
Authors: Childress James F.
Published: May 2020

This chapter originated in the author’s testimony before a congressional hearing on organ allocation policy. The ethical issues it addresses remain in play, as evidenced in the 2018–2019 debates about liver allocation policy. This chapter defends the fundamental conviction of the report of the Task Force on Organ Transplantation: Donated organs should be viewed as scarce public resources to be used for the welfare of the community. Organ procurement and transplant teams receive donated organs as “trustees” and “stewards” on behalf of the whole community, that is, the national community (with qualifications). Donated organs should be allocated to patients anywhere in the country according to ethically acceptable standards and logistical constraints, thus reducing the relevance of “accidents of geography” except where these are clearly important for transplantation outcomes. In short, patients, not transplant programs, should be put first. In accord with principles of justice and fairness, it is important to specify and balance, through a public process with public input, several criteria in policies of organ allocation: patient need and probability of successful outcome, along with time on the waiting list. Unless the criteria for patient selection are fair and are perceived to be fair, public distrust may hamper organ donation and perpetuate the scarcity of organs for transplantation.
Public Health Ethics
Authors: Childress James F. , Faden Ruth R. , Gaare [Bernheim] Ruth D. , Gostin Lawrence O. , Kahn Jeffrey , Bonnie Richard J. , Kass Nancy E. , Mastroianni Anna C. , Moreno Jonathan D. , Nieburg Phillip
Published: May 2020

This chapter, which grew out of a Greenwall Foundation–funded working group of a dozen or so ethicists, lawyers, and public health practitioners, provides a rough conceptual map of the terrain of public health ethics. It examines the nature of public health and public health interventions, and it identifies a number of general moral considerations (principles) relevant to public health policy and practice and often, especially as articulated in basic human rights, promotive of public health. Because these moral considerations are general and broad, they require specification and weighting. In cases of conflict, five “justificatory conditions” need to be met: effectiveness, proportionality, necessity, least infringement, and public justification. These conditions help to determine whether protecting or promoting public health warrants overriding individual liberty in particular situations.
Public Health and Civil Liberties
Authors: Childress James F.
Published: May 2020

This chapter focuses on public health ethics in a particular context—a liberal, pluralistic, democratic society that embodies explicit commitments to several basic civil liberties: bodily integrity, privacy, freedom of movement, freedom of association, and freedom of religion and conscience. When civil liberties set limits on public health interventions, a presumptivist framework is more defensible and helpful than either an absolutist or a contextualist one for determining appropriate interventions. This framework recognizes several conditions for rebutting the presumption, in certain circumstances, against interventions that infringe civil liberties. Through an exploration of the metaphor of the Intervention Ladder, proposed by the Nuffield Council on Bioethics, this chapter examines several possible ways to secure individuals’ cooperation with public health measures, such as vaccinations, directly observed therapy, and quarantine, without infringing their civil liberties. It is often possible to achieve compliance through expressing rather than imposing community.
John Stuart Mill’s Legacy for Public Health Ethics
Authors: Childress James F.
Published: May 2020

This chapter shows that the legacy of John Stuart Mill’s ethical framework for public health is far more complex and interesting than his On Liberty suggests, even when that classic work is properly understood. A largely neglected resource in Mill’s thought for public health is the ethical framework he actually used, in public testimony and correspondence, to address a heated controversy about the British government’s efforts in the Contagious Diseases Acts to reduce the transmission of sexually transmitted diseases. This displays his fuller range of ethical principles for public health, the way he resolved conflicts among those principles, and his somewhat surprising reluctance to endorse what we now call “harm-reduction measures,” which utilitarians, though not Mill, generally find justifiable in public health policy and practice.
Rings and arcs around evolved stars – II. The Carbon Star AFGL 3068 and the Planetary Nebulae NGC 6543, NGC 7009, and NGC 7027
Authors: Guerrero M A , Ramos-Larios G , Toalá J A , Balick B , Sabin L
Published: May 2020

We present a detailed comparative study of the arcs and fragmented ring-like features in the haloes of the planetary nebulae (PNe) NGC 6543, NGC 7009, and NGC 7027 and the spiral pattern around the carbon star AFGL 3068 using high-quality multi-epoch HST images. This comparison allows us to investigate the connection and possible evolution between the regular patterns surrounding AGB stars and the irregular concentric patterns around PNe. The radial proper motion of these features, ≃15 km s−1, are found to be consistent with the AGB wind and their linear sizes and interlapse times (500–1900 yr) also agree with those found around AGB stars, suggesting a common origin. We find evidence using radiative-hydrodynamic simulations that regular patterns produced at the end of the AGB phase become highly distorted by their interactions with the expanding PN and the anisotropic illumination and ionization patterns caused by shadow instabilities. These processes will disrupt the regular (mostly spiral) patterns around AGB stars, plausibly becoming the arcs and fragmented rings observed in the haloes of PNe.
Surrogate modelling the Baryonic Universe – I. The colour of star formation
Authors: Chaves-Montero Jonás , Hearin Andrew
Published: May 2020

The spectral energy distribution of a galaxy emerges from the complex interplay of many physical ingredients, including its star formation history (SFH), metallicity evolution, and dust properties. Using galaxpy, a new galaxy spectral prediction tool, and SFHs predicted by the empirical model universemachine and the cosmological hydrodynamical simulation IllustrisTNG, we isolate the influence of SFH on optical and near-infrared colours from 320 to 1080 Å at z = 0. By carrying out a principal component analysis, we show that physically motivated SFH variations modify galaxy colours along a single direction in colour space: the SFH-direction. We find that the projection of a galaxy’s present-day colours on to the SFH-direction is almost completely regulated by the fraction of stellar mass that the galaxy formed over the last billion years. Together with cosmic downsizing, this results in galaxies becoming redder as their host halo mass increases. We additionally study the change in galaxy colours due to variations in metallicity, dust attenuation, and nebular emission lines, finding that these properties vary broad-band colours along distinct directions in colour space relative to the SFH-direction. Finally, we show that the colours of low-redshift Sloan Digital Sky Survey galaxies span an ellipsoid with significant extent along two independent dimensions, and that the SFH-direction is well-aligned with the major axis of this ellipsoid. Our analysis supports the conclusion that variations in SFH are the dominant influence on present-day galaxy colours, and that the nature of this influence is strikingly simple.
Possible periodic activity in the repeating FRB 121102
Authors: Rajwade K M , Mickaliger M B , Stappers B W , Morello V , Agarwal D , Bassa C G , Breton R P , Caleb M , Karastergiou A , Keane E F , Lorimer D R
Published: May 2020

The discovery that at least some Fast Radio Bursts (FRBs) repeat has ruled out cataclysmic events as the progenitors of these particular bursts. FRB 121102 is the most well-studied repeating FRB but despite extensive monitoring of the source, no underlying pattern in the repetition has previously been identified. Here, we present the results from a radio monitoring campaign of FRB 121102 using the 76 m Lovell telescope. Using the pulses detected in the Lovell data along with pulses from the literature, we report a detection of periodic behaviour of the source over the span of 5 yr of data. We predict that the source is currently ‘off’ and that it should turn ‘on’ for the approximate MJD range 59002−59089 (2020 June 2 to 2020 August 28). This result, along with the recent detection of periodicity from another repeating FRB, highlights the need for long-term monitoring of repeating FRBs at a high cadence. Using simulations, we show that one needs at least 100 h of telescope time to follow-up repeating FRBs at a cadence of 0.5–3 d to detect periodicities in the range of 10–150 d. If the period is real, it shows that repeating FRBs can have a large range in their activity periods that might be difficult to reconcile with neutron star precession models.
Deprojecting galaxy-cluster cold fronts: evidence for bulk, magnetized spiral flows
Authors: Naor Yossi , Keshet Uri , Wang Qian H S , Reiss Ido
Published: May 2020

Tangential discontinuities known as cold fronts (CFs) are abundant in groups and clusters of galaxies (GCs). The relaxed, spiral-type CFs were initially thought to be isobaric, but a significant, $10{{\ \rm per\ cent}}$–$20{{\ \rm per\ cent}}$ jump in the thermal pressure Pt was reported when deprojected CFs were stacked, interpreted as missing Pt below the CFs (i.e. at smaller radii r) due to a locally enhanced non-thermal pressure Pnt. We report a significant (∼4.3σ) deprojected jump in Pt across a single sharp CF in the Centaurus cluster. Additional seven CFs are deprojected in the GCs A2029, A2142, A2204, and Centaurus, all found to be consistent (stacked: ∼1.9σ) with similar pressure jumps. Combining our sample with high quality deprojected CFs from the literature indicates pressure jumps at significance levels ranging between 2.7σ and 5.0σ, depending on assumptions. Our nominal results are consistent with Pnt ≃ (0.1–0.3)Pt just below the CF. We test different deprojection and analysis methods to confirm that our results are robust, and show that without careful deprojection, an opposite pressure trend may incorrectly be inferred. Analysing all available deprojected data, we also find: (i) small variations around the mean density and temperature CF contrast q within each GC, monotonically increasing with the GC mass M200 as $q\propto M_{200}^{0.23\pm 0.04}$; (ii) hydrostatic mass discontinuities indicating fast bulk tangential flows below all deprojected CFs, with a mean Mach number ∼0.76; and (iii) the newly deprojected CFs are consistent (stacked: ∼2.9σ) with a $1.25^{+0.09}_{-0.08}$ metallicity drop across the CF. These findings suggest that GCs quite generally harbour extended spiral flows.
The impact of spectra quality on nebular abundances
Authors: Rodríguez Mónica
Published: May 2020

I explore the effects of observational errors on nebular chemical abundances using a sample of 179 optical spectra of 42 planetary nebulae (PNe) observed by different authors. The spectra are analysed in a homogeneous way to derive physical conditions and ionic and total abundances. The effects of recombination on the [O ii] and [N ii] emission lines are estimated by including the effective recombination coefficients in the statistical equilibrium equations that are solved for O+ and N+. The results are shown to be significantly different than those derived using previous approaches. The O+ abundances derived with the blue and red lines of [O ii] differ by up to a factor of 6, indicating that the relative intensities of lines widely separated in wavelength can be highly uncertain. In fact, the He ii lines in the range 4000–6800 Å imply that most of the spectra are bluer than expected. Scores are assigned to the spectra using different criteria and the spectrum with the highest score for each PN is taken as the reference spectrum. The differences between the abundances derived with the reference spectrum and those derived with the other spectra available for each object are used to estimate the 1σ observational uncertainties in the final abundances: 0.11 dex for O/H and Ar/H, 0.14 dex for N/H, Ne/H, and Cl/H, and 0.16 dex for S/H.
SDSS-IV MaNGA: spatially resolved dust attenuation in spiral galaxies
Authors: Greener Michael J , Aragón-Salamanca Alfonso , Merrifield Michael R , Peterken Thomas G , Fraser-McKelvie Amelia , Masters Karen L , Krawczyk Coleman M , Boardman Nicholas F , Boquien Médéric , Andrews Brett H , Brinkmann Jonathan , Drory Niv
Published: May 2020

Dust attenuation in star-forming spiral galaxies affects stars and gas in different ways due to local variations in dust geometry. We present spatially resolved measurements of dust attenuation for a sample of 232 such star-forming spiral galaxies, derived from spectra acquired by the SDSS-IV MaNGA survey. The dust attenuation affecting the stellar populations of these galaxies (obtained using full spectrum stellar population fitting methods) is compared with the dust attenuation in the gas (derived from the Balmer decrement). Both of these attenuation measures increase for local regions of galaxies with higher star formation rates; the dust attenuation affecting the stellar populations increases more so than the dust attenuation in the gas, causing the ratio of the dust attenuation affecting the stellar populations to the dust attenuation in the gas to decrease for local regions of galaxies with higher star formation rate densities. No systematic difference is discernible in any of these dust attenuation quantities between the spiral arm and interarm regions of the galaxies. While both the dust attenuation in the gas and the dust attenuation affecting the stellar populations decrease with galactocentric radius, the ratio of the two quantities does not vary with radius. This ratio does, however, decrease systematically as the stellar mass of the galaxy increases. Analysis of the radial profiles of the two dust attenuation measures suggests that there is a disproportionately high concentration of birth clouds (incorporating gas, young stars, and clumpy dust) nearer to the centres of star-forming spiral galaxies.
See Change: VLT spectroscopy of a sample of high-redshift Type Ia supernova host galaxies
Authors: Williams S C , Hook I M , Hayden B , Nordin J , Aldering G , Boone K , Goobar A , Lidman C E , Perlmutter S , Rubin D , Ruiz-Lapuente P , Saunders C ,   (The Supernova Cosmology Project)
Published: May 2020

The Supernova Cosmology Project has conducted the ‘See Change’ programme, aimed at discovering and observing high-redshift (1.13 ≤ z ≤ 1.75) Type Ia supernovae (SNe Ia). We used multifilter Hubble Space Telescope (HST) observations of massive galaxy clusters with sufficient cadence to make the observed SN Ia light curves suitable for a cosmological probe of dark energy at z > 0.5. This See Change sample of SNe Ia with multi-colour light curves will be the largest to date at these redshifts. As part of the See Change programme, we obtained ground-based spectroscopy of each discovered transient and/or its host galaxy. Here, we present Very Large Telescope (VLT) spectra of See Change transient host galaxies, deriving their redshifts, and host parameters such as stellar mass and star formation rate. Of the 39 See Change transients/hosts that were observed with the VLT, we successfully determined the redshift for 26, including 15 SNe Ia at z > 0.97. We show that even in passive environments, it is possible to recover secure redshifts for the majority of SN hosts out to z = 1.5. We find that with typical exposure times of 3−4 h on an 8-m-class telescope we can recover ∼75 per cent of SN Ia redshifts in the range of 0.97 < z < 1.5. Furthermore, we show that the combination of HST photometry and VLT spectroscopy is able to provide estimates of host galaxy stellar mass that are sufficiently accurate for use in a mass-step correction in the cosmological analysis.
Accretion disc–jet couplings in X-ray binaries
Authors: Shen Pei-Xin , Gu Wei-Min
Published: May 2020

When the matter from a companion star is accreted towards the central compact accretor, i.e. a black hole (BH) or a neutron star (NS), an accretion disc and a jet outflow will form, providing bight X-ray and radio emission, which is known as X-ray binaries (XRBs). In the low/hard state, there exist disc–jet couplings in XRBs, but it remains uncertain whether the jet power comes from the disc or the central accretor. Moreover, black hole X-ray binaries (BHXRBs) have different properties compared with neutron star X-ray binaries (NSXRBs): quiescent BHXRBs are typically two to three orders of magnitude less luminous than NSXRBs in X-ray, whereas BHXRBs are more radio loud than NSXRBs. In observations, an empirical correlation has been established between radio and X-ray luminosity, $L_{\rm R} \propto L_{\rm X}^b$, where b ∼ 0.7 for BHXRBs and b ∼ 1.4 for non-pulsating NSXRBs. However, there are some outliers of BHXRBs showing unusually steep correlation as NSXRBs at higher luminosities. In this work, under the assumption that the origin of jet power is related to the internal energy of the inner disc, we apply our magnetized, radiatively efficient thin disc model and the well-known radiatively inefficient accretion flow model to NSXRBs and BHXRBs. We find that the observed radio/X-ray correlations in XRBs can be well understood by the disc–jet couplings.
Separating the intrinsic alignment signal and the lensing signal using self-calibration in photo-z surveys with KiDS450 and KV450 Data
Authors: Yao Ji , Pedersen Eske M , Ishak Mustapha , Zhang Pengjie , Agashe Anish , Xu Haojie , Shan Huanyuan
Published: May 2020

To reach the full potential for the next generation of weak lensing surveys, it is necessary to mitigate the contamination of intrinsic alignments (IAs) of galaxies in the observed cosmic shear signal. The self-calibration (SC) of IAs provides an independent method to measure the IA signal from the survey data and the photometric redshift information. It operates differently from the marginalization method based on the IA modelling. In this work, we present the first application of SC to the KiDS450 data and the KV450 data, to split directly the intrinsic shape–galaxy density (Ig) correlation signal and the gravitational shear–galaxy density (Gg) correlation signal, using the information from photometric redshift (photo-z). We achieved a clear separation of the two signals and performed several validation tests. Our measured signals are found to be in general agreement with the KiDS450 cosmic shear best-fitting cosmology, for both lensing and IA measurements. For KV450, we use partial (high-z) data, and our lensing measurements are also in good agreement with KV450 cosmic shear best fit, while our IA signal suggests a larger IA amplitude for the high-z sample. We discussed the impact of photo-z quality on IA detection and several other potential systematic biases. Finally, we discuss the potential application of the information extracted for both the lensing signal and the IA signal in future surveys.
Asymmetric surface brightness structure of caustic crossing arc in SDSS J1226+2152: a case for dark matter substructure
Authors: Dai Liang , Kaurov Alexander A , Sharon Keren , Florian Michael , Miralda-Escudé Jordi , Venumadhav Tejaswi , Frye Brenda , Rigby Jane R , Bayliss Matthew
Published: May 2020

We study the highly magnified arc SGAS J122651.3+215220 caused by a star-forming galaxy at zs = 2.93 crossing the lensing caustic cast by the galaxy cluster SDSS J1226+2152 (zl = 0.43), using Hubble Space Telescope observations. We report in the arc several asymmetric surface brightness features whose angular separations are a fraction of an arcsecond from the lensing critical curve and appear to be highly but unequally magnified image pairs of underlying compact sources, with one brightest pair having clear asymmetry consistently across four filters. One explanation of unequal magnification is microlensing by intracluster stars, which induces independent flux variations in the images of individual or groups of source stars in the lensed galaxy. For a second possibility, intracluster dark matter subhaloes invisible to telescopes effectively perturb lensing magnifications near the critical curve and give rise to persistently unequal image pairs. Our modelling suggests, at least for the most prominent identified image pair, that the microlensing hypothesis is in tension with the absence of notable asymmetry variation over a six-year baseline, while subhaloes of ∼106–$10^8\, \mathrm{ M}_\odot$ anticipated from structure formation with cold dark matter typically produce stationary and sizable asymmetries. We judge that observations at additional times and more precise lens models are necessary to stringently constrain temporal variability and robustly distinguish between the two explanations. The arc under this study is a scheduled target of a Director’s Discretionary Early Release Science program of the James Webb Space Telescope, which will provide deep images and a high-resolution view with integral field spectroscopy.
A catalogue of open cluster radii determined from Gaia proper motions
Authors: Sánchez Néstor , Alfaro Emilio J , López-Martínez Fátima
Published: May 2020

In this work, we improve a previously published method to calculate in a reliable way the radius of an open cluster (OC). The method is based on the behaviour of stars in the proper motion space as the sampling changes in the position space. Here, we describe the new version of the method and show its performance and robustness. Additionally, we apply it to a large number of OCs using data from Gaia second data release to generate a catalogue of 401 clusters with reliable radius estimations. The range of obtained apparent radii goes from Rc = 1.4 ± 0.1 arcmin (for the cluster FSR 1651) to Rc = 25.5 ± 3.5 arcmin (for NGC 2437). Cluster linear sizes follow very closely a lognormal distribution with a mean characteristic radius of Rc = 3.7 pc, and its high radius tail can be fitted by a power law as $N \propto R_c^{-3.11\pm 0.35}$. Additionally, we find that number of members, cluster radius, and age follow the relationship $N_c \propto R_c^{1.2\pm 0.1} \cdot T_c^{-1.9\pm 0.4}$ where the younger and more extensive the cluster, the more members it presents. The proposed method is not sensitive to low density or irregular spatial distributions of stars and, therefore, is a good alternative or complementary procedure to calculate OC radii not having previous information on star memberships.
snapshot: connections between internal and surface properties of massive stars
Authors: Farrell Eoin J , Groh Jose H , Meynet Georges , Eldridge J J , Ekström Sylvia , Georgy Cyril
Published: May 2020

We introduce snapshot, a technique to systematically compute stellar structure models in hydrostatic and thermal equilibrium based on three structural properties – core mass Mcore, envelope mass Menv, and core composition. This approach allows us to connect these properties of stellar interiors to the luminosity and effective temperature Teff in a more systematic way than with stellar evolution models. We compute core-H burning models with total masses of Mtotal = 8–60 M⊙ and central H mass fractions from 0.70 to 0.05. Using these, we derive an analytical relationship between Mcore, Mtotal, and central H abundance that can be readily used in rapid stellar evolution algorithms. In contrast, core-He burning stars can have a wide range of combinations of Mcore, Menv, and core compositions. We compute core-He burning models with Mcore = 2–9 M⊙, Menv = 0–50 M⊙, and central He mass fractions of 0.50 and 0.01. Models with Mcore/Mtotal from 0.2 to 0.8 have convective envelopes, low Teff and will appear as red supergiants (RSGs). For a given Mcore, they exhibit a small variation in luminosity (0.02 dex) and Teff ($\sim 400\, \mathrm{K}$) over a wide range of Menv ($\sim$2–20 M⊙). This means that it is not possible to derive RSG masses from luminosities and Teff alone. We derive the following relationship between Mcore and the total luminosity of an RSG during core He burning: log Mcore ≃ 0.44log L/L⊙ − 1.38. At Mcore/Mtotal ≈ 0.2, our models exhibit a bistability and jump from an RSG to a BSG structure. Our models with Mcore/Mtotal > 0.8, which correspond to stripped stars produced by mass-loss or binary interaction, show that Teff has a strong dependence on Menv, Mcore, and the core composition. We constrain the mass of one of these stripped stars in a binary system, HD 45166, and find it to be less than its estimated dynamical mass. When a large observational sample of stripped stars becomes available, our results can be used to constrain their Mcore, Menv, mass-loss rates, and the physics of binary interaction.
frankenstein: protoplanetary disc brightness profile reconstruction at sub-beam resolution with a rapid Gaussian process
Authors: Jennings Jeff , Booth Richard A , Tazzari Marco , Rosotti Giovanni P , Clarke Cathie J
Published: May 2020

Interferometric observations of the mm dust distribution in protoplanetary discs are now showing a ubiquity of annular gap and ring substructures. Their identification and accurate characterization are critical to probing the physical processes responsible. We present frankenstein (frank), an open source code that recovers axisymmetric disc structures at a sub-beam resolution. By fitting the visibilities directly, the model reconstructs a disc’s 1D radial brightness profile non-parametrically using a fast (≲1 min) Gaussian process. The code avoids limitations of current methods that obtain the radial brightness profile either by extracting it from the disc image via non-linear deconvolution at the cost of reduced fit resolution or by assumptions placed on the functional forms of disc structures to fit the visibilities parametrically. We use mock Atacama Large Millimeter Array observations to quantify the method’s intrinsic capability and its performance as a function of baseline-dependent signal-to-noise ratio. Comparing the technique to profile extraction from a clean image, we motivate how our fits accurately recover disc structures at a sub-beam resolution. Demonstrating the model’s utility in fitting real high- and moderate-resolution observations, we conclude by proposing applications to address open questions on protoplanetary disc structure and processes.