Milliarcsecond Localization of the Repeating FRB 20201124A

Very long baseline interferometric (VLBI) localizations of repeating fast radio bursts (FRBs) have demonstrated a diversity of local environments: from nearby star-forming regions to globular clusters. Here we report the VLBI localization of FRB 20201124A using an ad hoc array of dishes that also participate in the European VLBI Network (EVN). In our campaign, we detected 18 bursts from FRB 20201124A at two separate epochs. By combining the visibilities from both epochs, we were able to localize FRB 20201124A with a 1 sigma uncertainty of 2.7 mas. We use the relatively large burst sample to investigate astrometric accuracy and find that for greater than or similar to 20 baselines (greater than or similar to 7 dishes) we can robustly reach milliarcsecond precision even using single-burst data sets. Subarcsecond precision is still possible for single bursts, even when only similar to 6 baselines (four dishes) are available. In such cases, the limited uv coverage for individual bursts results in very high side-lobe levels. Thus, in addition to the peak position from the dirty map, we also explore smoothing the structure in the dirty map by fitting Gaussian functions to the fringe pattern in order to constrain individual burst positions, which we find to be more reliable. Our VLBI work places FRB 20201124A 710 +/- 30 mas (1 sigma uncertainty) from the optical center of the host galaxy, consistent with originating from within the recently discovered extended radio structure associated with star formation in the host galaxy. Future high-resolution optical observations, e.g., with Hubble Space Telescope, can determine the proximity of FRB 20201124A\u27s position to nearby knots of star formation

Drug Resistance in Eukaryotic Microorganisms

Eukaryotic microbial pathogens are major contributors to illness and death globally. Although much of their impact can be controlled by drug therapy as with prokaryotic microorganisms, the emergence of drug resistance has threatened these treatment efforts. Here, we discuss the challenges posed by eukaryotic microbial pathogens and how these are similar to, or differ from, the challenges of prokaryotic antibiotic resistance. The therapies used for several major eukaryotic microorganisms are then detailed, and the mechanisms that they have evolved to overcome these therapies are described. The rapid emergence of resistance and the restricted pipeline of new drug therapies pose considerable risks to global health and are particularly acute in the developing world. Nonetheless, we detail how the integration of new technology, biological understanding, epidemiology and evolutionary analysis can help sustain existing therapies, anticipate the emergence of resistance or optimize the deployment of new therapies

Making sense of Integrated Pest Management (IPM) in the light of evolution

Integrated Pest Management (IPM) is a holistic approach to combat pests (including herbivores, pathogens, and weeds) using a combination of preventive and curative actions, and only applying synthetic pesticides when there is an urgent need. Just as the recent recognition that an evolutionary perspective is useful in medicine to understand and predict interactions between hosts, diseases, and medical treatments, we argue that it is crucial to integrate an evolutionary framework in IPM to develop efficient and reliable crop protection strategies that do not lead to resistance development in herbivores, pathogens, and weeds. Such a framework would not only delay resistance evolution in pests, but also optimize each element of the management and increase the synergies between them. Here, we outline key areas within IPM that would especially benefit from a thorough evolutionary understanding. In addition, we discuss the difficulties and advantages of enhancing communication among research communities rooted in different biological disciplines and between researchers and society. Furthermore, we present suggestions that could advance implementation of evolutionary principles in IPM and thus contribute to the development of sustainable agriculture that is resilient to current and emerging pests

Discovery of a new azole resistance mechanism in Aspergillus fumigatus through whole genome sequencing and sexual crossing.

Contains fulltext : 110932.pdf (publisher's version ) (Open Access

2,6-Bis(oxazolinyl)phenylnickel(II) bromide and 2,6-bis(ketimine)phenylnickel(II) bromide: synthesis, structural features, and redox properties

2,6-Bis(oxazolinyl)phenylnickel bromide complexes [NiBr(R,R'-Phebox)] (2) were synthesized via two synthetic routes (A and B). In route A, selective bis-ortho lithiation of [R,R'-PheboxBr], followed by a transmetalation reaction with [NiBr2(PEt3)(2)], yielded not only complexes 2 with an eta(3)-mer-N,C,N'-bonded Phebox ligand but also [NiBr(R,R'-Phebox)(PEt3)(2)], 7, where the nickel center is eta(1)-C bonded to the intra-annular C-ipso of the Phebox ligand. Coordination of two PEt3 ligands completes the square-planar coordination sphere of the Ni center in 7. When R = t-Bu, R' = H, only complex 7c was formed. Alternatively, when route B (oxidative addition with [Ni(cod)(2)], cod = cyclooctadiene) was followed, selective formation of complexes 2 was observed. X-ray crystal structures were obtained for [NiBr-(i-Pr,H-Phebox)] (2b) and [NiBr(bis(ketimine)phenyl)] (3). The Ni centers have square-planar geometries with a planar, eta(3)-mer-N,C,N' coordination of the terdentate ligand systems. Complexes 2 were found to be inactive as catalysts in the atom-transfer radical polymerization (ATRP) reaction of methyl methacrylate (MMA) and in the atom-transfer radical addition (ATRA, Kharasch addition) reaction of CCl4 to MMA. This is ascribed to the relatively high oxidation potential of Ni-II-Phebox complexes, which excludes the (reversible) formation of a d(7)-Ni-III-Phebox complex, a crucial condition for subsequent reactions. Cyclovoltammetry (CV) experiments ((n-Bu)(4)NBr as supporting electrolyte) showed no electrochemical waves between -1.00 and +1.50 V (Ag/AgCl reference electrode, (n-Bu)(4)NBr as supporting electrode). Theoretical calculations showed that the energy (E-ox) needed for the oxidation reaction occurring during the CV experiments is considerably higher for [NiBr(Me,Me-Phebox)] (1.87 eV) and [NiBr(bis(ketimine)phenyl)] (1.90 eV) than for [NiBr(NCN)] (1) (1.45 eV)