224 research outputs found
RACIAL DISCRIMINATION IN HIRE/PURCHASE LENDING IN APARTHEID SOUTH AFRICA
A partial-observability model finds evidence of racial discrimination by retailers of consumer durables in apartheid South Africa. In particular, black households are 13 percentage points more likely to demand a hire/purchase loan but not to have one supplied than are other households, all else equal.Consumer finance, disequilibrium models, racial discrimination, truncated and censored models, South Africa, Financial Economics,
Discrimination by Formal Lenders in South Africa
Censored (Tobit) regression is used to estimate the effects of race, location of residence, and sex of the household head on formal debt held by South African households. The magnitude of the effects suggests that lenders discriminate and that formal financial markets could be improved even without technical innovation
PIC simulation of a strong double layer in a nonrelativistic plasma flow: Electron acceleration to ultrarelativistic speeds
Two charge- and current neutral plasma beams are modelled with a
one-dimensional PIC simulation. The beams are uniform and unbounded. The
relative speed between both beams is 0.4c. One beam is composed of electrons
and protons and one out of protons and negatively charged oxygen (dust). All
species have the temperature 9 keV. A Buneman instability develops between the
electrons of the first beam and the protons of the second beam. The wave traps
the electrons, which form plasmons. The plasmons couple energy into the ion
acoustic waves, which trap the protons of the second beam. A proton phase space
hole grows, which develops through its interaction with the oxygen and the
heated electrons into a rarefaction pulse. This pulse drives a strong ion
acoustic double layer, which accelerates a beam of electrons to about 50 MeV,
which is comparable to the proton kinetic energy. The proton distribution
eventually evolves into an electrostatic shock. Beams of charged particles
moving at such speeds may occur in the foreshock of supernova remnant shocks.
This double layer is thus potentially relevant for the electron acceleration
(injection) into the diffusive shock acceleration by supernova remnants shocks
Impact of percutaneous coronary intervention timing on 5-year outcome in patients with non-ST-segment elevation acute coronary syndromes. The âwait a dayâ approach might be safer
Background The OPTIMA trial was a randomised multicentre trial exploring the influence of the timing of percutaneous coronary intervention (PCI) on patient outcomes in an intermediate to high risk non-ST-elevation acute coronary syndrome (NSTE-ACS) population. In order to decide the best treatment strategy for patients presenting with NSTEACS, long-term outcomes are essential. Methods Five-year follow-up data from 133 of the 142 patients could be retrieved (94 %). The primary endpoint was a composite of death and spontaneous myocardial infarction (MI). Spontaneous MI was defined as MI occurring more than 30 days after randomisation. Secondary endpoints were the individual outcomes of death, spontaneous MI or re-PCI. Results No significant difference with respect to the primary endpoint was observed (17.8 vs. 10.1 %; HR 1.55, 95 % CI: 0.73â4.22, p = 0.21). There was no significant difference in mortality rate. However, spontaneous MI was significantly more common in the group receiving immediate PCI (11.0 vs. 1.4 %; HR 4.46, 95 % CI: 1.21â16.50, p = 0.02). We did not find a significant difference between the groups with respect to re-PCI rate. Conclusion There was no difference in the composite of death and spontaneous MI. The trial suggests an increased long-term risk of spontaneous MI for patients treated with immediate PCI
The development and psychometric evaluation of the Internet Disorder Scale (IDS-15)
Introduction:
Previously published research suggests that improvement in the assessment of Internet addiction (IA) is paramount in advancing the field. However, little has been done to address inconsistencies in the assessment of IA using a more updated framework. The aim of the present study was to develop a new instrument to assess IA based on a modification of the nine Internet Gaming Disorder (IGD) criteria as suggested by the American Psychiatric Association in the latest (fifth) edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), and to provide a taxonomy of the potential risk of IA risk among participants.
Methods:
A heterogeneous sample of Internet users (n=1,105) was recruited online (61.3% males, mean age 33 years). Construct validity of the new instrument â Internet Disorder Scale (IDS-15) â was assessed by means of factorial, convergent, and discriminant validity. Criterion-related validity and reliability were also investigated. Additionally, latent profile analysis (LPA) was carried out to differentiate and characterize Internet users based on their potential IA risk.
Results:
The construct and criterion-related validity of the IDS-15 were both warranted. The IDS-15 proved to be a valid and reliable tool. Using the LPA, participants were classed as âlow addiction riskâ (n = 183, 18.2%), âmedium addiction riskâ (n = 456, 41.1%), and âhigh addiction riskâ (n = 455, 40.77%). Furthermore, key differences emerged among these classes in terms of age, relationship status, cigarette consumption, weekly Internet usage, age of Internet use initiation, and IDS-15 total scores.
Conclusions:
The present findings support the viability of using adapted IGD criteria as a framework to assess IA
Bioelectromagnetics research within an Australian context: the Australian centre for electromagnetic bioeffects research (ACEBR)
Mobile phone subscriptions continue to increase across the world, with the electromagnetic fields (EMF) emitted by these devices, as well as by related technologies such as Wi-Fi and smart meters, now ubiquitous. This increase in use and consequent exposure to mobile communication (MC)-related EMF has led to concern about possible health effects that could arise from this exposure. Although much research has been conducted since the introduction of these technologies, uncertainty about the impact on health remains. The Australian Centre for Electromagnetic Bioeffects Research (ACEBR) is a National Health and Medical Research Council Centre of Research Excellence that is undertaking research addressing the most important aspects of the MC-EMF health debate, with a strong focus on mechanisms, neurodegenerative diseases, cancer, and exposure dosimetry. This research takes as its starting point the current scientific status quo, but also addresses the adequacy of the evidence for the status quo. Risk communication research complements the above, and aims to ensure that whatever is found, it is communicated effectively and appropriately. This paper provides a summary of this ACEBR research (both completed and ongoing), and discusses the rationale for conducting it in light of the prevailing science.Sarah P. Loughran ... Jim Manavis ... Robert Vink ... et al
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Massive stars in extremely metal-poor galaxies: a window into the past
Cosmic history has witnessed the lives and deaths of multiple generations of massive stars, all of them invigorating their host galaxies with ionizing photons, kinetic energy, fresh material, and stellar-mass black holes. Ubiquitous engines as they are, astrophysics needs a good understanding of their formation, evolution, properties and yields throughout the history of the Universe, and with decreasing metal content mimicking the environment at the earliest epochs. Ultimately, a physical model that could be extrapolated to zero metallicity would enable tackling long-standing questions such as âWhat did the first, very massive stars of the Universe look like?â or âWhat was their role in the re-ionization of the Universe?â Yet, most of our knowledge of metal-poor massive stars is drawn from one single point in metallicity. Massive stars in the Small Magellanic Cloud (SMC, âŒ1/5Zâ ) currently serve as templates for low-metallicity objects in the early Universe, even though significant differences with respect to massive stars with poorer metal content have been reported. This White Paper summarizes the current knowledge on extremely (sub-SMC) metal poor massive stars, highlighting the most outstanding open questions and the need to supersede the SMC as standard. A new paradigm can be built from nearby extremely metal-poor galaxies that make a new metallicity ladder, but massive stars in these galaxies are out of reach to current observational facilities. Such a task would require an L-size mission, consisting of a 10m-class space telescope operating in the optical and the ultraviolet ranges. Alternatively, we propose that ESA unites efforts with NASA to make the LUVOIR mission concept a reality, thus continuing the successful partnership that made the Hubble Space Telescope one of the greatest observatories of all time
Unfolded Protein Response as a Compensatory Mechanism and Potential Therapeutic Target in PLN R14del Cardiomyopathy
BACKGROUND: Phospholamban (PLN) is a critical regulator of calcium cycling and contractility in the heart. The loss of arginine at position 14 in PLN (R14del) is associated with dilated cardiomyopathy with a high prevalence of ventricular arrhythmias. How the R14 deletion causes dilated cardiomyopathy is poorly understood, and there are no disease-specific therapies. METHODS: We used single-cell RNA sequencing to uncover PLN R14del disease mechanisms in human induced pluripotent stem cells (hiPSC-CMs). We used both 2-dimensional and 3-dimensional functional contractility assays to evaluate the impact of modulating disease-relevant pathways in PLN R14del hiPSC-CMs. RESULTS: Modeling of the PLN R14del cardiomyopathy with isogenic pairs of hiPSC-CMs recapitulated the contractile deficit associated with the disease in vitro. Single-cell RNA sequencing revealed the induction of the unfolded protein response (UPR) pathway in PLN R14del compared with isogenic control hiPSC-CMs. The activation of UPR was also evident in the hearts from PLN R14del patients. Silencing of each of the 3 main UPR signaling branches (IRE1, ATF6, or PERK) by siRNA exacerbated the contractile dysfunction of PLN R14del hiPSC-CMs. We explored the therapeutic potential of activating the UPR with a small molecule activator, BiP (binding immunoglobulin protein) inducer X. PLN R14del hiPSC-CMs treated with BiP protein inducer X showed a dose-dependent amelioration of the contractility deficit in both 2-dimensional cultures and 3-dimensional engineered heart tissues without affecting calcium homeostasis. CONCLUSIONS: Together, these findings suggest that the UPR exerts a protective effect in the setting of PLN R14del cardiomyopathy and that modulation of the UPR might be exploited therapeutically
Very Massive Stars in the local Universe
Recent studies have claimed the existence of very massive stars (VMS) up to 300 M â in the local Universe. As this finding may represent a paradigm shift for the canonical stellar upper-mass limit of 150 M â, it is timely to discuss the status of the data, as well as the far-reaching implications of such objects. We held a Joint Discussion at the General Assembly in Beijing to discuss (i) the determination of the current masses of the most massive stars, (ii) the formation of VMS, (iii) their mass loss, and (iv) their evolution and final fate. The prime aim was to reach broad consensus between observers and theorists on how to identify and quantify the dominant physical processe
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