Detection and molecular characterisation of plasmidic AmpC b-lactamases in Klebsiella pneumoniae isolates from a tertiary-care hospital in Dublin, Ireland

This study determined the types of AmpC enzymes produced by Klebsiella pneumoniae isolates resistant to third-generation cephalosporins and the clonality of these isolates. The presence of AmpC enzymes was identified by cephalosporin-cloxacillin synergy tests. Genes encoding AmpC enzymes were characterised by PCR and sequencing. Pulsed-field gel electrophoresis (PFGE) was used to type the isolates. Fifteen K. pneumoniae isolates were positive for bla(AmpC), 13 were positive for bla(ACC-1) and two were positive for bla(DHA-1). Production of the DHA-1 enzyme was inducible. The ampR gene was identified upstream of the bla(DHA-1) gene. PFGE demonstrated the polyclonal origin of the isolates carrying bla(ACC-1)

Splenic Rupture in a COVID-19 Patient – A Case Report

Background: It is well known that the Coronavirus disease 2019 (COVID-19) causes coagulation changes, requiring frequent monitoring for potential sequelae such as myocardial infarction and stroke. Non-traumatic splenic rupture is a rare and poorly understood occurrence in the clinical setting. Possible causes of nontraumatic splenic rupture include neoplasm, infection, inflammatory disease, iatrogenic and mechanical causes. Furthermore, increased intrasplenic tension, increased abdominal pressure, and thrombotic vascular occlusion are possible mechanisms. The Case: We report a case of splenic rupture in a COVID-19 patient. Our patient was a 52-year-old black man, presenting with diarrhea and moderate dyspnea, who was found to be COVID-19 positive. He had a past medical history significant for end-stage renal disease, chronic anemia, and aortic valve replacement. In an otherwise uneventful, 7-day hospital course, the patient’s stay abruptly resulted in a nontraumatic splenic rupture and demise. In this report, we have evaluated the likelihood of COVID-19 causing splenic rupture in a patient with no prior splenic disease. Conclusion: This case highlights the possibility of splenic rupture in otherwise normally recovering COVID-19 patients, particularly in the presence of comorbid conditions of renal failure and anticoagulation, with increased abdominal pressure during routine defecation. This information may assist in furthering the pathophysiology of COVID-19 and its life-threatening complications. In patients with COVID-19, non-traumatic splenic rupture should be considered as one of the differential diagnoses in patients who present with abdominal pain and early recognition of the same, owing to a high index of suspicion, can be lifesaving

Shift Towards P Limitation with N Deposition?

Atmospheric nitrogen (N) deposition is altering biogeochemical cycling in forests and interconnected lakes of the northeastern US, and may shift nutrient limitation from N toward other essential elements, such as phosphorus (P). Whether this shift is occurring relative to N deposition gradients across the northeastern US has not been investigated. We used datasets for the northeastern US and the Adirondack sub-region to evaluate whether P limitation is increasing where N deposition is high at two geographic scales, based on N:P mass ratios. Using a model- selection approach, we determined that foliar N for dominant tree species and lake dissolved inorganic N (DIN) increased coincident with increasing N deposition, independent of relationships between foliar N or lake DIN and precipitation or temperature. Foliar P also increased with N deposition across the northeastern US for seven of eight deciduous species, but changed less across the Adirondacks. Foliar N:P therefore declined at the highest levels of N deposition for most deciduous species across the region (remaining nearly constant for most conifers and increasing only for black cherry and hemlock), but increased across all species in the Adirondacks. Ratios between DIN and total P (DIN:TP) in lakes were unrelated to N deposition regionally but increased across the Adirondacks. Thus, nutrient limitation patterns shifted from N toward P for dominant trees, and further toward P for predominantly P-limited lakes, at the sub-regional but not regional scale. For the northeastern US overall, accumulated N deposition may be insufficient to drive nutrient limitation from N toward P; alternatively, elements other than P (e.g., calcium, magnesium) may become limiting as N accumulates. The consistent Adirondack foliar and lake response could provide early indication of shifts toward P limitation within the northeastern US, and together with regional patterns, suggests that foliar chemistry could be a predictor of lake chemistry in the context of N deposition across the region

Gaia CCDs: charge transfer inefficiency measurements between five years of flight

The European Space Agency’s Gaia spacecraft was launched in December 2013 and has been in orbit at the Earth-Sun Lagrange point 2 (L2) for over 6 years. The spacecraft measures the positions, distances, space motions and many other physical characteristics of around one billion stars in the Milky Way and beyond. It has a focal plane of 106 Charge-Coupled Devices (CCDs) which have all been performing well but have been measuring a small but quantifiable degradation in performance in time due to Non-Ionizing Energy Loss (NIEL) damage from interstellar radiation. This NIEL damage produces trap defects which can capture charge from signals and reduces the quality of the data. Gaia’s original mission lifetime was planned to be around 5 years and the pre-flight testing and radiation damage analysis was tailored around those timescales as well as with the projected solar activity before launch. Closer to the time of launch and during Gaia’s years of orbit, it has been noted that the solar activity was lower than what was initially predicted. From the previous analysis of in-flight data in 2016, it was calculated that Gaia was experiencing an order of magnitude less radiation damage than was predicted. This paper describes the analysis of charge calibration data and corresponding Charge Transfer Inefficiency (CTI) measurements from the in-flight CCDs, both near the beginning of the mission and after more than 5 years in orbit to quantify the radiation damage impact. These sets of results can be compared with those from the pre-flight tests which can be used to evaluate and understand the differences between the on-ground and in-flight results

Temperature-dependent rate coefficients for the reactions of the hydroxyl radical with the atmospheric biogenics isoprene, alpha-pinene and delta-3-carene

Pulsed laser methods for OH generation and detection were used to study atmospheric degradation reactions for three important biogenic gases: OHCisoprene (Reaction R1), OH+α-pinene (Reaction R2) and OH+Δ- 3-carene (Reaction R3). Gas-phase rate coefficients were characterized by non-Arrhenius kinetics for all three reactions. For (R1), k1 (241-356 K)= (1:93±0:08)× 10-11 exp{(466±12)/T} cm3 molecule-1 s-1 was determined, with a room temperature value of k1 (297 K)= (9:3± 0:4)×10-11 cm3 molecule-1 s-1, independent of bath-gas pressure (5-200 Torr) and composition (MDN2 or air). Accuracy and precision were enhanced by online optical monitoring of isoprene, with absolute concentrations obtained via an absorption cross section, αisoprene = (1:28±0:06)× 10-17 cm2 molecule-1 at λ = 184:95 nm, determined in this work. These results indicate that significant discrepancies between previous absolute and relative-rate determinations of k1 result in part from σ values used to derive the isoprene concentration in high-precision absolute determinations. Similar methods were used to determine rate coefficients (in 10-11 cm3 molecule-1 s-1/ for (R2)-(R3): k2 (238-357 K)= (1:83±0:04) ×exp{(330±6)/T } and k3 (235-357 K)= (2:48±0:14) ×exp{(357±17)/T }. This is the first temperature-dependent dataset for (R3) and enables the calculation of reliable atmospheric lifetimes with respect to OH removal for e.g. boreal forest springtime conditions. Room temperature values of k2 (296 K)= (5:4±0:2) ×10-11 cm3 molecule-1 s-1 and k3 (297 K)= (8:1±0:3)×10-11 cm3 molecule-1 s-1 were independent of bathgas pressure (7-200 Torr, N2 or air) and in good agreement with previously reported values. In the course of this work, 184.95 nm absorption cross sections were determined: σ = (1:54±0:08) ×10-17 cm2 molecule-1 for α-pinene and (2:40±0:12)×10-17 cm2 molecule-1 for 1-3-carene

European climate response to tropical volcanic eruptions over the last half millennium

We analyse the winter and summer climatic signal following 15 major tropical volcanic eruptions over the last half millennium based on multi-proxy reconstructions for Europe. During the first and second post-eruption years we find significant continental scale summer cooling and somewhat drier conditions over Central Europe. In the Northern Hemispheric winter the volcanic forcing induces an atmospheric circulation response that significantly follows a positive NAO state connected with a significant overall warm anomaly and wetter conditions over Northern Europe. Our findings compare well with GCM studies as well as observational studies, which mainly cover the substantially shorter instrumental period and thus include a limited set of major eruptions

Are Steadily Moving Crystals Unstable?

We study the dynamics of small fluctuations about the uniform state of a crystal moving through a dissipative medium, e.g. a sedimenting colloidal crystal or a moving flux lattice, using a set of continuum equations for the displacement fields, and a one-dimensional driven lattice-gas model for the coupled concentration and tilt fields. For the colloidal crystal we predict a continuous nonequilibrium phase transition to a clumped state above a critical Peclet number.Comment: 4 pages, revtex, 2 .eps figures, uses epsf.sty; To be published in Phys. Rev. Lett. This version is substantially rewritten but the essential content is the same as befor