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The SARAO MeerKAT Galactic Plane Survey filamentary source catalogue
Get PDFWe present a catalogue of filamentary structures identified in the SARAO (South African Radio Astronomy Observatory)
MeerKAT 1.3 GHz Galactic Plane Survey (SMGPS).We extract 933 filaments acrossthe survey area, 803 of which (∼86 per cent)
are associated with extended radio structures (e.g. supernova remnants and H II regions), while 130 (∼14 per cent) are largely
isolated. We classify filaments as thermal or non-thermal via their associated mid-infrared emission and find that 77/130
(∼59 per cent) of the isolated sources are likely to be non-thermal, and are therefore excellent candidates for the first isolated,
non-thermal radio filaments observed outside of the Galactic Centre (GC). Comparing the morphological properties of these
non-thermal candidates to the non-thermal filaments observed towards the GC, we find that the GC filaments are on the whole
angularly narrower and shorter than those across the SMGPS, potentially an effect of distance. The SMGPS filaments have
flux densities similar to those of the GC; however, the distribution of the latter extends to higher flux densities. If the SMGPS
filaments were closer than the GC population, it would imply a more energetic population of cosmic ray electrons in the GC.
We find that the filament position angles in the SMGPS are uniformly distributed, implying that the local magnetic field traced
by the filaments does not follow the large-scale Galactic field. Finally, although we have clearly shown that filaments are not
unique to the GC, the GC nevertheless has the highest density of filaments in the Milky Way
Protein-induced membrane asymmetry modulates OMP folding kinetics and stability
Get PDFBiological membranes are asymmetric structures, with asymmetry arising from differences in lipid identity in each leaflet of the bilayer, as well as non-uniform distribution of lipids and small molecules in the membrane. Proteins can also induce and modulate membrane asymmetry based on their shape, sequence and interactions with lipids. How membrane asymmetry affects macromolecular behaviour is poorly understood because of the complexity of natural membrane systems, and difficulties in creating relevant asymmetric bilayer systems in vitro. Here, we present a method exploiting the efficient, unidirectional folding of the transmembrane β-barrel outer membrane protein, OmpA, to create asymmetric proteoliposomes with protein-induced dipoles of known direction (arising from sequence variation engineered into the OmpA loops). We then characterise the folding kinetics and stability of different OmpA variants into these proteoliposomes. We find that both the primary sequence of the folding OmpA and the dipole of the membrane into which folding occurs play an important role for modulating the rate of folding. Critically, we find that by complementarily matching the charge on the folding protein to the membrane dipole it is possible to enhance both the folding kinetics and the stability of the folded OmpA. The results hint at how cells might exploit loop charge in membrane-embedded proteins to manipulate membrane environments for adaptation and survival
Continuous Flow Synthesis of Copper Oxide Nanoparticles Enabling Rapid Screening of Synthesis‐Structure‐Property Relationships
Get PDFAn adjustable and scalable method for the continuous flow synthesis of cupric oxide nanoparticles (CuO NPs), targetted the reduction of their activity to synthetic biomembranes to inform the fabrication of nanoparticles (NPs) with reduced toxicity for commercial applications. By manipulating key factors; temperature, residence time, and the ratio of precursor to reductant, precise control over the morphology of CuO NPs is achieved with X-ray diffraction (XRD) and transmission electron microscopy (TEM) confirming the formation of needle-shaped CuO NPs. One-variable-at-a-time studies reveal a relationship between the synthesis conditions and the characteristics of the resultant NPs, with CuO NPs varying controllably between 10-50 nanometres in length and 4-10 nanometres in width. Subsequently, Design of Experiment (DoE) exploration of the biomembrane activity of the CuO NPs intriguingly revealed only minimal effects on their membrane-disruptive properties in the chemical space defined by the synthesis conditions explored. This study marks a significant milestone, as it introduces a facile, easy to scale, continuous flow synthesis of CuO NPs, with control over the length and width of the needle NPs and reveals that, regardless of the exact shape, the NPs have minimal impact on biomembranes, prompting more detailed exploration in the future for use in biomedical applications
SLAPPs in England and Wales: The Issues and the Evidence (briefing)
Get PDFIn light of the UK government's renewed commitment to introduce further measures concerning SLAPPs, this paper identifies significant definitional and evidential issues that remain undiagnosed and under-explored in anti-SLAPPs lobbying successes to date by which prospective legislative change has been heavily influenced. It argues for a moratorium on further legislative change unless and until the Law Commission is tasked with properly considering these issues
A real-time, scalable, fast and resource-efficient decoder for a quantum computer
Get PDFThe development of quantum computers will require the careful management of the noise effects associated with qubit performance. However, the decoders responsible for diagnosing noise-induced computational errors must use resources efficiently to enable scaling to large qubit counts and cryogenic operation. They must also operate at speed, to avoid an exponential slowdown in the logical clock rate of the quantum computer. To overcome these challenges, we introduce the Collision Clustering decoder and demonstrate its implementation on field-programmable gate array (FPGA) and application-specific integrated circuit (ASIC) hardware. We simulate logical memory experiments using the leading quantum error correction scheme (the surface code) and demonstrate megahertz decoding speed—matching the requirements of fast-operating modalities such as superconducting qubits—up to an 881 qubit surface code with the FPGA and 1,057 qubit surface code with the ASIC. The ASIC design occupies 0.06 mm2 and consumes only 8 mW of power
Characterising the molecular line emission in the asymmetric Oph-IRS 48 dust trap: Temperatures, timescales, and sub-thermal excitation
Get PDFContext. The ongoing physical and chemical processes in planet-forming disks set the stage for planet (and comet) formation. The asymmetric disk around the young star Oph-IRS 48 has one of the most well-characterised chemical inventories, showing molecular emission from a wide variety of species at the dust trap: from simple molecules, such as CO, SO, SO₂, and H₂CO, to large complex organics, such as CH₂OH, CH₃OCHO, and CH₃OCH₃. One of the explanations for the asymmetric structure in the disk is dust trapping by a perturbation-induced vortex.
Aims. We aimed to constrain the excitation properties of the molecular species SO₂, CH₃OH, and H₂CO, for which we have used 13, 22, and 7 transitions of each species, respectively. We further characterised the extent of the molecular emission, which differs among molecules, through the determination of important physical and chemical timescales at the location of the dust trap. We also investigated whether the anticyclonic motion of the potential vortex influences the observable temperature structure of the gas.
Methods. Through a pixel-by-pixel rotational diagram analysis, we created maps of the rotational temperatures and column densities of SO₂ and CH₃OH. To determine the temperature structure of H₂CO, we have used line ratios of the various transitions in combination with non-local thermal equilibrium (LTE) RADEX calculations. The timescales for freeze-out, desorption, photodissociation, and turbulent mixing at the location of the dust trap were determined using an existing thermochemical model.
Results. Our rotational diagram analysis yields temperatures of T = 54.8±1.4 K (SO₂) and T = 125.5−3.5+3.7 K (CH₃OH) at the emission peak positions of the respective lines. As the SO₂rotational diagram is well characterised and points towards thermalised emission, the emission must originate from a layer close to the midplane where the gas densities are high enough. The rotational diagram of CH₃OH is, in contrast, dominated by scatter and subsequent non-LTE RADEX calculations suggest that both CH₃OH and H₂CO must be sub-thermally excited higher up in the disk (z/r ~ 0.17–0.25). For H₂CO, the derived line ratios suggest temperatures in the range of T ~ 150-350 K. The SO₂temperature map hints at a potential radial temperature gradient, whereas that of CH₃OH is nearly uniform and that of H₂CO peaks in the central regions. We, however, do not find any hints of the vortex influencing the temperature structure across the dust trap. The longer turbulent mixing timescale, compared to that of photodissociation, does provide an explanation for the expected vertical emitting heights of the observed molecules. On the other hand, the short photodissociation timescales are able to explain the wider azimuthal molecular extent of SO₂compared to CH₃OH. The short timescales are, however, not able to explain the wider azimtuhal extent of the H₂CO emission. Instead, it can be explained by a secondary reservoir that is produced through the gas-phase formation routes, which are sustained by the photodissociation products of, for example, CH₃OH and H₂O.
Conclusions. Based on our derived temperatures, we expect SO₂ to originate from deep inside the disk, whereas CO comes from a higher layer and both CH₃OH and H₂CO emit from the highest emitting layer. The sub-thermal excitation of CH₃OH and H2CO suggests that our derived (rotational) temperatures underestimate the kinetic temperature. Given the non-thermal excitation of important species, such as H₂CO and CH₃OH, it is important to use non-LTE approaches when characterising low-mass disks, such as that of IRS 48. Furthermore, for the H₂CO emission to be optically thick, as expected from an earlier derived isotopic ratio, we suggest that the emission must originate from a small radial ‘sliver’ with a width of ~10 au, located at the inner edge of the dust trap
Workplace autonomy and mental health
Get PDFThis paper explores the relationship between work-related autonomy and mental health. Using Understanding Society data from the United Kingdom, I assess the association between mental health and autonomy, defined across five different dimensions, using a range of different controls, including person and occupation fixed effects. I find low work-related autonomy consistently associates with poor mental health. The degree of selection bias on observable controls is small. Finally, I bound causal effects under assumptions about the degree of confoundedness of unobservables, and assess the possibility of reverse causality
Causes of death after bariatric surgery: long-term study of 10 years
Get PDFBackground
There is a lack of up-to-date research addressing the causes of death and predictors of long-term mortality after bariatric surgery.
Methods
This was a single-centre retrospective study. Trust records were used to identify deceased patients and their medical history. The demographic data, comorbidities, cause of death, and time since surgery were retrieved and tabulated. Data was recoded to allow for use in IBM SPSS.
Results
There were 39 deaths amongst 891 patients who underwent bariatric surgery between 15th June 2010 to 18th September 2022. The main cause of death was pneumonia and respiratory causes with 15.4% of the cohort. A history of asthma/COPD had an association with the cause of death (p = 0.021). A history of hypertension, ischaemic heart disease (IHD), and smoking were all associated with a higher age at death, whilst a history of IHD was associated with a higher number of days from operation to death. Age at operation and number of comorbidities both correlated with age at death, and multiple linear regression of age at death with age at operation and number of comorbidities as predictors was significant (p < 0.001). A Cox regression found age at operation to have a significant effect on survival, with a hazard ratio of 1.063 (95% CI:1.027 to 1.100, p < 0.001).
Conclusion
Pneumonia and respiratory causes are the largest causes of long-term mortality after bariatric surgery. The only factor found to have a detrimental effect on all-cause mortality was age at operation which reduced survival. Hypertension, IHD, and smoking are indirect factors that are associated with mortality
Anion localization on termini of a non‐fullerene acceptor aids charge transport
Get PDFNon-fullerene acceptors have revolutionised organic photovoltaics. However, greater fundamental understanding is needed of the crucial relationships between molecular structure and photophysical mechanisms. Herein, a combination of spectroscopic, morphology, and device characterization techniques are used to explore these relationships for a high-performing non-fullerene acceptor, anti-PDFC. It focuses on transient absorption spectroscopy across multiple timescales and ultrafast time-resolved vibrational spectroscopy to acquire the “holy grail” of simultaneous structural and dynamic information for anti-PDFC and its blend with the well-known conjugated polymer PM6. Most significantly, it is observed that the singlet exciton of anti-PDFC is localised on the perylene diimide central core of the molecule, but the radical anion is primarily localised on the fluorinated indene malonitrile terminal units (which are common to many state-of-the-art non-fullerene acceptors, including the Y6 family). This electron transfer from the central core to the termini of an adjacent molecule is facilitated by a close interaction between the termini and the central core, as evidenced by single crystal diffraction data and excited state calculations. Finally, the very efficient charge extraction measured for PM6:anti-PDFC photovoltaic devices may be correlated with this anion localization, enabling effective charge transport channels and thus enhancing device performance
Sceptics and champions: participant insights on the use of partial randomization to allocate research culture funding
Get PDFAs part of the shift towards a more equitable research culture, funders are reconsidering traditional approaches to peer review. In doing so, they seek to minimize bias towards certain research ideas and researcher profiles, to ensure greater inclusion of disadvantaged groups, to improve review quality, to reduce burden, and to enable more transformative research. This paper presents the rationale and findings from a trial of partially randomized funding allocation (PRA) used to internally distribute Research England’s Enhancing Research Culture fund at the University of Leeds. Of 26 eligible applications, six fell in the upper midfield on quality assessment and were randomized. Of this subset, one received the available funding. Qualitative data from applicants, reviewers, and moderators in the trial suggest modest gains regarding the reduction or perception of bias and efficiency of peer review. There were variable benefits of the feedback that PRA provides. A range of concerns emerged about PRA’s perceived fairness, bluntness, and threat to quality. Based on the behavioural responses we captured, we present strategic and operational recommendations for professionals working in research evaluation who are interested in adopting PRA as a way of improving research culture. For example, we highlight the importance of (1) sharing data on the role of chance in traditional peer review, and (2) considering the benefits and risks of PRA at both group and individual applicant levels
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