339 research outputs found
The case for scaling up renewable energy investments in fragile and conflict-affected situations
The impressive drop in the cost of clean technologies and the local practical potential of solar PV are making renewable energy an increasingly viable option from an economic perspective in fragile settings. Clean energy investment also has direct implications for tackling climate change, improving the socioeconomic inclusion of marginalised groups, and state-building â through greater legitimacy, resilience, and commitment to peace. These elements highlight the great potential that investments in renewable, reliable, and affordable energy hold to help countries escape state fragility
Conceptions of agency and constraint for HIV-positive patients and healthcare workers to support long-term engagement with antiretroviral therapy care in Khayelitsha, South Africa.
In the context of the optimism around antiretroviral therapy (ART) as prevention of HIV/AIDS, addressing the barriers to long-term ART adherence is critical. This is particularly important given the tendency to individualise or use a blame discourse when exploring why HIV-infected patients "fail" to adequately adhere to ART, and not sufficiently exploring contextual reasons for poor adherence that may require varying solutions. This study took place at three clinics and one hospital in Khayelitsha, South Africa, to document the contextual factors that challenged ART adherence in this community. Interviews were conducted with 20 HIV-infected patients who had defaulted on their ART and were subsequently admitted to Khayelitsha hospital for clinical complications, and 9 ART service providers including doctors, nurses and HIV counsellors. Interviews assessed the reasons patients defaulted on ART and explored ways this could be prevented. Data from both groups were analysed collectively using thematic analysis. While the interviews revealed a landscape of environmental risks threatening adherence to ART, all patients managed to overcome the identified barriers at some point in their treatment phase, indicating the fluidity of patients' needs and decision making. Patients reported that distrustful relationships with service providers could inhibit their understanding of ART and/or interrupt their follow-up at clinics. Patients described their rationale and agency underlying non-adherence, such as testing their bodies' physical limits without ART medication. The study speaks to the need to appreciate contextual social and structural barriers related to ART adherence, and how these are negotiated differently by specific sub-groups, to support an appropriate response. It is imperative to not solely emphasise loss to follow-up but also assess patients' subjective trajectory of their ART journey, decision making and agency with adhering to ART, their relations with healthcare workers, and how these dynamics are intertwined with broader constraints in health systems
A Push-Button Molecular Switch
The preparation, characterization, and switching mechanism of a unique single-station mechanically switchable hetero[2]catenane are reported. The facile synthesis utilizing a âthreading-followed-by-clippingâ protocol features Cu^(2+)-catalyzed Eglinton coupling as a mild and efficient route to the tetrathiafulvalene-based catenane in high yield. The resulting mechanically interlocked molecule operates as a perfect molecular switch, most readily described as a âpush-buttonâ switch, whereby two discrete and fully occupied translational states are toggled electrochemically at incredibly high rates. This mechanical switching was probed using a wide variety of experimental techniques as well as quantum-mechanical investigations. The fundamental distinctions between this single-station [2]catenane and other more traditional bi- and multistation molecular switches are significant
Synthesis and Characterization of Ruthenium and Rhenium Nucleosides
We report the synthesis and characterization of new ruthenium and rhenium nucleosides [Ru(tolyl-acac)_2(IMPy)-T] (tolyl-acac = di(p-methylbenzonatemethane), IMPy = 2â-iminomethylpyridine, T = thymidine) (5) and [Re(CO)_3(IMPy)-T]Cl (9), respectively. Structural analysis of 9 shows that the incorporation of this metal complex causes minimal perturbation to the sugar backbone and the nucleobase. Eletrochemical (5, E_(1/2) = 0.265 V vs NHE; 9, E_(1/2) = 1.67 V vs NHE), absorption (5, λ_(max) = 600, 486 nm; 9, λ_(max) = 388 nm), and emission (9, λ_(max) = 770 nm, Ï = 17 ns) data indicate that 5 and 9 are suitable probes for DNA-mediated ground-state electron-transfer studies. The separation and characterization of diastereoisomers of 5 and bipyridyl-based ruthenium nucleoside [Ru(bpy)_2(IMPy)-T]^(2+) (7) are reported
A luminous X-ray transient in SDSS J143359.16+400636.0: a likely tidal disruption event
We present the discovery of a luminous X-ray transient, serendipitously
detected by Swift's X-ray Telescope (XRT) on 2020 February 5, located in the
nucleus of the galaxy SDSS J143359.16+400636.0 at z=0.099 (luminosity distance
Mpc). The transient was observed to reach a peak luminosity of
erg s in the 0.3--10 keV X-ray band, which was
times more than the peak optical/UV luminosity. Optical, UV, and X-ray
lightcurves from the Zwicky Transient Facility (ZTF) and Swift show a decline
in flux from the source consistent with , and observations with
NuSTAR and Chandra show a soft X-ray spectrum with photon index
. The X-ray/UV properties are inconsistent with well known
AGN properties and have more in common with known X-ray tidal disruption events
(TDE), leading us to conclude that it was likely a TDE. The broadband spectral
energy distribution (SED) can be described well by a disk blackbody model with
an inner disk temperature of K, with a large
fraction (%) of the disk emission up-scattered into the X-ray band. An
optical spectrum taken with Keck/LRIS after the X-ray detection reveals LINER
line ratios in the host galaxy, suggesting low-level accretion on to the
supermassive black hole prior to the event, but no broad lines or other
indications of a TDE were seen. The stellar velocity dispersion implies the
mass of the supermassive black hole powering the event is log(/), and we estimate that at peak the Eddington
fraction of this event was 50%. This likely TDE was not identified by
wide-field optical surveys, nor optical spectroscopy, indicating that more
events like this would be missed without wide-field UV or X-ray surveys.Comment: Accepted for publication by ApJ. Accepted version now replaces
initial submissio
A New Class of Changing-Look LINERs
We report the discovery of six active galactic nuclei (AGN) caught "turning
on" during the first nine months of the Zwicky Transient Facility (ZTF) survey.
The host galaxies were classified as LINERs by weak narrow forbidden line
emission in their archival SDSS spectra, and detected by ZTF as nuclear
transients. In five of the cases, we found via follow-up spectroscopy that they
had transformed into broad-line AGN, reminiscent of the changing-look LINER
iPTF 16bco. In one case, ZTF18aajupnt/AT2018dyk, follow-up HST UV and
ground-based optical spectra revealed the transformation into a narrow-line
Seyfert 1 (NLS1) with strong [Fe VII, X, XIV] and He II 4686 coronal lines.
Swift monitoring observations of this source reveal bright UV emission that
tracks the optical flare, accompanied by a luminous soft X-ray flare that peaks
~60 days later. Spitzer follow-up observations also detect a luminous
mid-infrared flare implying a large covering fraction of dust. Archival light
curves of the entire sample from CRTS, ATLAS, and ASAS-SN constrain the onset
of the optical nuclear flaring from a prolonged quiescent state. Here we
present the systematic selection and follow-up of this new class of
changing-look LINERs, compare their properties to previously reported
changing-look Seyfert galaxies, and conclude that they are a unique class of
transients well-suited to test the uncertain physical processes associated with
the LINER accretion state.Comment: Submitted to ApJ, 31 pages, 17 Figures (excluding Appendix due to
file size constraints but will be available in electronic version
Severe CTE and TDP-43 pathology in a former professional soccer player with dementia: a clinicopathological case report and review of the literature
In the last decades, numerous post-mortem case series have documented chronic traumatic encephalopathy (CTE) in former contact-sport athletes, though reports of CTE pathology in former soccer players are scarce. This study presents a clinicopathological case of a former professional soccer player with young-onset dementia. The patient experienced early onset progressive cognitive decline and developed dementia in his mid-50Â s, after playing soccer for 12Â years at a professional level. While the clinical picture mimicked Alzheimer's disease, amyloid PET imaging did not provide evidence of elevated beta-amyloid plaque density. After he died in his mid-60Â s, brain autopsy showed severe phosphorylated tau (p-tau) abnormalities fulfilling the neuropathological criteria for high-stage CTE, as well as astrocytic and oligodendroglial tau pathology in terms of tufted astrocytes, thorn-shaped astrocytes, and coiled bodies. Additionally, there were TAR DNA-binding protein 43 (TDP-43) positive cytoplasmic inclusions in the frontal lobe and hippocampus, and Amyloid Precursor Protein (APP) positivity in the axons of the white matter. A systematic review of the literature revealed only 13 other soccer players with postmortem diagnosis of CTE. Our report illustrates the complex clinicopathological correlation of CTE and the need for disease-specific biomarkers
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