The impact of dark matter cusps and cores on the satellite galaxy population around spiral galaxies

We use N-body simulations to study the effects that a divergent (i.e. ‘cuspy') dark matter profile introduces on the tidal evolution of dwarf spheroidal galaxies (dSphs). Our models assume cosmologically motivated initial conditions where dSphs are dark-matter-dominated systems on eccentric orbits about a host galaxy composed of a dark halo and a baryonic disc. We find that the resilience of dSphs to tidal stripping is extremely sensitive to the cuspiness of the inner halo profile; whereas dwarfs with a cored profile can be easily destroyed by the disc component, those with cusps always retain a bound remnant, even after losing more than 99.99 per cent of the original mass. For a given halo profile, the evolution of the structural parameters as driven by tides is controlled solely by the total amount of mass lost. This information is used to construct a semi-analytic code that follows the tidal evolution of individual satellites as they fall into a more massive host, which allows us to simulate the hierarchical build-up of spiral galaxies assuming different halo profiles and disc masses. We find that tidal encounters with discs tend to decrease the average mass of satellite galaxies at all galactocentric radii. Of all satellites, those accreted before re-ionization (z≳ 6), which may be singled out by anomalous metallicity patterns, provide the strongest constraints on the inner profile of dark haloes. These galaxies move on orbits that penetrate the disc repeatedly and survive to the present day only if haloes have an inner density cusp. We show that the size-mass relationship established from Milky Way (MW) dwarfs strongly supports the presence of cusps in the majority of these systems, as cored models systematically underestimate the masses of the known ultra-faint dSphs. Our models also indicate that a massive M31 disc may explain why many of its dSphs with suitable kinematic data fall below the size-mass relationship derived from MW dSphs. We also examine whether our modelling can constrain the mass threshold below which star formation is suppressed in dark matter haloes. We find that luminous satellites must be accreted with masses above 108-109 M⊙ in order to explain the size-mass relation observed in MW dwarf

Phylogenetic analyses reveal multiple new stem-boring Tetramesa taxa (Hymenoptera: Eurytomidae): implications for the biological control of invasive African grasses

Many native South African grass species have become invasive elsewhere in the world. The application of biological control to invasive grasses has been approached with trepidation in the past, primarily due to concerns of a perceived lack of host specific herbivores. This has changed in recent times, and grasses are now considered suitable candidates. The Tetramesa Walker genus (Hymenoptera: Eurytomidae) has been found to contain species that are largely host specific to a particular grass species, or complex of closely related congeners. Very little taxonomic work exists for Tetramesa in the southern hemisphere, and the lack of morphological variability between many Tetramesa species has made identification difficult. This limits the ability to assess the genus for potential biological control agents. Species delimitation analyses indicated 16 putative novel southern African Tetramesa taxa. Ten of these were putative Tetramesa associated with Eragrostis curvula (Schrad.) Nees and Sporobolus pyramidalis Beauv. and S. natalensis Steud., which are alien invasive weeds in Australia. Of these ten Tetramesa taxa, eight were only found on a single host plant, while two taxa were associated with multiple species in a single grass genus. The Tetramesa spp. on S. pyramidalis and S. africanus were deemed suitably host-specific to be used as biological control agents. Field host range data for the Tetramesa species on E. curvula revealed that the wasp may not be suitably host specific for use as a biological control agent. However, further host specificity testing on non-target native Australian species is required

The ISLANDS project I: Andromeda XVI, An Extremely Low Mass Galaxy not Quenched by Reionization

Based on data aquired in 13 orbits of HST time, we present a detailed evolutionary history of the M31 dSph satellite Andromeda XVI, including its life-time star formation history, the spatial distribution of its stellar populations, and the properties of its variable stars. And XVI is characterized by prolonged star formation activity from the oldest epochs until star formation was quenched ~6 Gyr ago, and, notably, only half of the mass in stars of And XVI was in place 10 Gyr ago. And XVI appears to be a low mass galaxy for which the early quenching by either reionization or starburst feedback seems highly unlikely, and thus, is most likely due to an environmental effect (e.g., an interaction), possibly connected to a late infall in the densest regions of the Local Group. Studying the star formation history as a function of galactocentric radius, we detect a mild gradient in the star formation history: the star formation activity between 6 and 8 Gyr ago is significantly stronger in the central regions than in the external regions, although the quenching age appears to be the same, within 1 Gyr. We also report the discovery of 9 RR Lyrae stars, 8 of which belong to And XVI. The RR Lyrae stars allow a new estimate of the distance, (m-M)0= 23.72+/-0.09 mag, which is marginally larger than previous estimates based on the tip of the red giant branch.Comment: Accepted for publication on Ap

The ISLAndS project II: The Lifetime Star Formation Histories of Six Andromeda dSphs

The Initial Star formation and Lifetimes of Andromeda Satellites (ISLAndS) project uses Hubble Space Telescope imaging to study a representative sample of six Andromeda dSph satellite companion galaxies. The main goal of the program is to determine whether the star formation histories (SFHs) of the Andromeda dSph satellites demonstrate significant statistical differences from those of the Milky Way, which may be attributable to the different properties of their local environments. Our observations reach the oldest main sequence turn-offs, allowing a time resolution at the oldest ages of ~ 1 Gyr, which is comparable to the best achievable resolution in the MW satellites. We find that the six dSphs present a variety of SFHs that are not strictly correlated with luminosity or present distance from M31. Specifically, we find a significant range in quenching times (lookback times from 9 to 6 Gyr), but with all quenching times more than ~ 6 Gyr ago. In agreement with observations of Milky Way companions of similar mass, there is no evidence of complete quenching of star formation by the cosmic UV background responsible for reionization, but the possibility of a degree of quenching at reionization cannot be ruled out. We do not find significant differences between the SFHs of the three members of the vast, thin plane of satellites and the three off-plane dSphs. The primary difference between the SFHs of the ISLAndS dSphs and Milky Way dSph companions of similar luminosities and host distances is the absence of very late quenching (< 5 Gyr ago) dSphs in the ISLAndS sample. Thus, models that can reproduce satellite populations with and without late quenching satellites will be of extreme interest.Comment: 24 pages, 11 figures, 3 tables, submitted to the Ap

Star formation at the edge of the Local Group: a rising star formation history in the isolated galaxy WLM

We present the star formation history (SFH) of the isolated (D~970 kpc) Local Group dwarf galaxy WLM measured from color-magnitude diagrams constructed from deep Hubble Space Telescope imaging. Our observations include a central (0.5 $r_h$) and outer field (0.7 $r_h$) that reach below the oldest main sequence turnoff. WLM has no early dominant episode of star formation: 20% of its stellar mass formed by ~12.5 Gyr ago (z~5). It also has an SFR that rises to the present with 50% of the stellar mass within the most recent 5 Gyr (z<0.7). There is evidence of a strong age gradient: the mean age of the outer field is 5 Gyr older than the inner field despite being only 0.4 kpc apart. Some models suggest such steep gradients are associated with strong stellar feedback and dark matter core creation. The SFHs of real isolated dwarf galaxies and those from the the Feedback In Realistic Environment suite are in good agreement for $M_{\star}(z=0) \sim 10^7-10^9 M_{\odot}$, but in worse agreement at lower masses ($M_{\star}(z=0) \sim 10^5-10^7 M_{\odot}$). These differences may be explainable by systematics in the models (e.g., reionization model) and/or observations (HST field placement). We suggest that a coordinated effort to get deep CMDs between HST/JWST (crowded central fields) and WFIRST (wide-area halo coverage) is the optimal path for measuring global SFHs of isolated dwarf galaxies.Comment: 13 pages, 13 Figures, 4 Tables. Re-submitted to MNRAS after addressing the referee's comment

Rationale and design of the British Heart Foundation (BHF) Coronary Microvascular Angina (CorMicA) stratified medicine clinical trial.

BACKGROUND: Coronary angiography is performed to assess for obstructive coronary artery disease (CAD), but "nonobstructive CAD" is a common finding. Microvascular or vasospastic angina may be relevant, but routine confirmatory testing is not evidence based and thus rarely performed. AIM: The aim was to assess the effect of stratified medicine guided by coronary function testing on the diagnosis, treatment, and well-being of patients with angina and nonobstructive CAD. DESIGN: The BHF CorMicA trial is a prospective, multicenter, randomized, blinded, sham-controlled trial of stratified medicine (NCT03193294). All-comers referred for elective coronary angiography for investigation of suspected CAD will be screened. Following informed consent, eligible patients with angina and nonobstructive CAD will be randomized 1:1 immediately in the catheter laboratory to either coronary artery function-guided diagnosis and treatment (intervention group) or not (control group). Coronary function will be assessed using a pressure-temperature-sensitive guidewire and adenosine followed by pharmacological testing with intracoronary acetylcholine. Patients will be stratified into endotypes with linked therapy. The primary outcome is change in Seattle Angina Questionnaire score at 6 months. Secondary outcomes include safety, feasibility, diagnostic utility (impact on diagnosis and diagnostic certainty), and clinical utility (impact on treatment and investigations). Health status is a key secondary outcome assessed according to the following domains: quality of life, treatment satisfaction, illness perception, physical activity, and anxiety-depression score. Patients with obstructive disease who are not randomized will form a registry group who will be followed up as a comparator for secondary outcomes including health status. Health and economic outcomes will be evaluated in the longer term using electronic health record linkage. VALUE: CorMicA is a proof-of-concept clinical trial of a disruptive stratified intervention with potential benefits to patients and health care providers

Rationale and design of the British Heart Foundation (BHF) Coronary Microvascular Function and CT Coronary Angiogram (CorCTCA) study

Background: Microvascular and/or vasospastic anginas are relevant causes of ischemia with no obstructive coronary artery disease (INOCA) in patients after computed tomography coronary angiography (CTCA). Objectives: Our research has 2 objectives. The first is to undertake a diagnostic study, and the second is to undertake a nested, clinical trial of stratified medicine. Design: A prospective, multicenter, randomized, blinded, sham-controlled trial of stratified medicine (NCT03477890) will be performed. All-comers referred for clinically indicated CTCA for investigation of suspected coronary artery disease (CAD) will be screened in 3 regional centers. Following informed consent, eligible patients with angina symptoms are enrolled before CTCA and remain eligible if CTCA excludes obstructive CAD. Diagnostic study: Invasive coronary angiography involving an interventional diagnostic procedure (IDP) to assess for disease endotypes: (1) angina due to obstructive CAD (fractional flow reserve ≤0.80); (2) microvascular angina (coronary flow reserve &lt;2.0 and/or index of microvascular resistance &gt;25); (3) microvascular angina due to small vessel spasm (acetylcholine); (4) vasospastic angina due to epicardial coronary spasm (acetylcholine); and (5) noncoronary etiology (normal coronary function). The IDP involves direct invasive measurements using a diagnostic coronary guidewire followed by provocation testing with intracoronary acetylcholine. The primary outcome of the diagnostic study is the reclassification of the initial CTCA diagnosis based on the IDP. Stratified medicine trial: Participants are immediately randomized 1:1 in the catheter laboratory to therapy stratified by endotype (intervention group) or not (control group). The primary outcome of the trial is the mean within-subject change in Seattle Angina Questionnaire score at 6 months. Secondary outcomes include safety, feasibility, diagnostic utility (impact on diagnosis and certainty), and clinical utility (impact on treatment and investigations). Health status assessments include quality of life, illness perception, anxiety-depression score, treatment satisfaction, and physical activity. Participants who are not randomized will enter a follow-up registry. Health and economic outcomes in the longer term will be assessed using electronic patient record linkage. Value: CorCTCA will prospectively characterize the prevalence of disease endotypes in INOCA and determine the clinical value of stratified medicine in this population

A decade of biological control of Parthenium hysterophorus L.(Asteraceae) in South Africa reviewed: introduction of insect agents and their status

The annual herb, Parthenium hysterophorus L. (Asteraceae: Heliantheae) is a severe terrestrial invader globally. Infestations reduce crop yield, limit available grazing, hinder conservation efforts, and affect human and animal health in Africa, Asia and Australia, and on associated islands. Due to the impact and threat of further invasion of P. hysterophorus, a biological control (biocontrol) programme was initiated in 2003 in South Africa. This review discusses the research and implementation activities undertaken on the insect agents from 2011 to 2020. During this period, the stem-boring weevil Listronotus setosipennis Hustache (Coleoptera: Curculionidae), leaf-feeding beetle Zygogramma bicolorata Pallister (Coleoptera: Chrysomelidae) and seed-feeding weevil Smicronyx lutulentus Dietz (Coleoptera: Curculionidae), were found to be host specific and approved for release. Releases of mass-reared insect agents have been concentrated particularly in north-eastern South Africa, where P. hysterophorus infestations are most prolific. Post-release monitoring studies indicated localised establishment and impact of L. setosipennis and S. lutulentus. Listronotus setosipennis persisted through severe drought conditions, and although it disperses slowly, larval feeding is structurally damaging. Establishment of S. lutulentus is improving, reducing seed production where it is established. Zygogramma bicolorata resulted in defoliation at a few sites, but establishment has been poor and the beetle has been absent since 2019. Although a combination of fungal and insect agents were demonstrated to reduce P. hysterophorus, additional natural enemies could improve control. Consequently, the stem-galling moth Epiblema strenuana Walker (Lepidoptera: Tortricidae) and root-crown boring moth Carmenta sp. nr. ithacae (Beutenmüller) (Lepidoptera: Sesiidae) remain under evaluation. The management of P. hysterophorus in South Africa has been guided by the development of a national strategy, which incorporates multiple management methods, including biocontrol. International collaborations have intensified as a growing number of countries begin to utilize biocontrol to manage P. hysterophorus. Despite the progress towards biocontrol of P. hysterophorus during this period, increased utilisation of approved agents and the introduction of additional agents are necessary to achieve greater control

FAST INdiCATE Trial protocol. Clinical efficacy of functional strength training for upper limb motor recovery early after stroke : neural correlates and prognostic indicators

© 2013 The Authors. International Journal of Stroke published by John Wiley & Sons Ltd on behalf of World Stroke Organization. Funded by: Efficacy and Mechanism Evaluation programme. Grant Number: 10/60/30 Medical Research Council (MRC)Peer reviewedPublisher PD

Stellar Metallicities and Kinematics in a Gas-Rich Dwarf Galaxy: First Calcium Triplet Spectroscopy of RGB Stars in WLM

We present the first determination of the radial velocities and metallicities of 78 red giant stars in the isolated dwarf irregular galaxy WLM. Observations of the calcium II triplet in these stars were made with FORS2 at the VLT-UT2 in two separated fields of view in WLM, and the [Fe/H] values were conformed to the Carretta & Gratton (1997) metallicity scale. The mean metallicity is = -1.27 +/- 0.04 dex, with a standard deviation of 0.37. We find that the stars in the inner field are more metal rich by [Fe/H] =0.30 +/- 0.06 dex. These results are in agreement with previous photometric studies that found a radial population gradient, as well as the expectation of higher metallicities in the central star forming regions. Age estimates using Victoria-Regina stellar models show that the youngest stars in the sample (< 6 Gyr) are more metal rich by [Fe/H] = 0.32 +/- 0.08 dex. These stars also show a lower velocity dispersion at all elliptical radii compared to the metal-poor stars. Kinematics for the whole red giant sample suggest a velocity gradient approximately half that of the gas rotation curve, with the stellar component occupying a thicker disk decoupled from the HI rotation plane. Taken together, the kinematics, metallicities, and ages in our sample suggest a young metal-rich, and kinematically cold stellar population in the central gas-rich regions of WLM, surrounded by a separate dynamically hot halo of older, metal poor stars.Comment: 10 pages, 12 figures, 5 tables. Accepted for publication in the Ap