Multicellular eukaryotes coevolve with microbial pathogens, which exert strong selective pressure on the immune systems of their hosts. Plants and animals use intracellular proteins of the ...nucleotide-binding domain, leucine-rich repeat (NLR) superfamily to detect many types of microbial pathogens. The NLR domain architecture likely evolved independently and convergently in each kingdom, and the molecular mechanisms of pathogen detection by plant and animal NLRs have long been considered to be distinct. However, microbial recognition mechanisms overlap, and it is now possible to discern important key trans-kingdom principles of NLR-dependent immune function. Here, we attempt to articulate these principles. We propose that the NLR architecture has evolved for pathogen-sensing in diverse organisms because of its utility as a tightly folded "hair trigger" device into which a virtually limitless number of microbial detection platforms can be integrated. Recent findings suggest means to rationally design novel recognition capabilities to counter disease.
ABSTRACT
This work explores whether gravitational waves (GWs) from neutron star (NS) mountains can be detected with current second-generation and future third-generation GW detectors. In particular, ...we focus on a scenario where transient mountains are formed immediately after an NS glitch. In a glitch, an NS’s spin frequency abruptly increases and then often exponentially recovers back to, but never quite reaches, the spin frequency prior to the glitch. If the recovery is ascribed to an additional torque due to a transient mountain, we find that GWs from that mountain are marginally detectable with Advanced LIGO at design sensitivity and is very likely to be detectable for third-generation detectors such as the Einstein Telescope. Using this model, we are able to find analytical expressions for the GW amplitude and its duration in terms of observables.
Modelling neutron star mountains Gittins, F; Andersson, N; Jones, D I
Monthly notices of the Royal Astronomical Society,
02/2021, Letnik:
500, Številka:
4
Journal Article
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Odprti dostop
ABSTRACT
As the era of gravitational-wave astronomy has well and truly begun, gravitational radiation from rotating neutron stars remains elusive. Rapidly spinning neutron stars are the main targets ...for continuous-wave searches since, according to general relativity, provided they are asymmetrically deformed, they will emit gravitational waves. It is believed that detecting such radiation will unlock the answer to why no pulsars have been observed to spin close to the break-up frequency. We review existing studies on the maximum mountain that a neutron star crust can support, critique the key assumptions and identify issues relating to boundary conditions that need to be resolved. In light of this discussion, we present a new scheme for modelling neutron star mountains. The crucial ingredient for this scheme is a description of the fiducial force which takes the star away from sphericity. We consider three examples: a source potential which is a solution to Laplace’s equation, another solution which does not act in the core of the star and a thermal pressure perturbation. For all the cases, we find that the largest quadrupoles are between a factor of a few to two orders of magnitude below previous estimates of the maximum-mountain size.
ABSTRACT
It was recently reported that there exists a population of ‘glitch candidates’ and ‘antiglitch candidates’ which are effectively small spin-ups and spin-downs of a neutron star with ...magnitudes smaller than those seen in typical glitches. The physical origin of these small events is not yet understood. In this paper, we outline a model that can account for the changes in spin, and crucially, is independently testable with gravitational wave observations. In brief, the model posits that small spin-up/spin-down events are caused by the excitation and decay of non-axisymmetric f-modes which radiate angular momentum away in a burst-like way as gravitational waves. The model takes the change in spin frequency as an input and outputs the initial mode amplitude and the signal-to-noise ratio achievable from gravitational wave detectors. We find that the model presented here will become falsifiable once third generation gravitational wave detectors, like the Einstein Telescope and Cosmic Explorer, begin taking data.
ABSTRACT
Understanding the evolution of the angle χ between a magnetar’s rotation and magnetic axes sheds light on the star’s birth properties. This evolution is coupled with that of the stellar ...rotation Ω, and depends on the competing effects of internal viscous dissipation and external torques. We study this coupled evolution for a model magnetar with a strong internal toroidal field, extending previous work by modelling – for the first time in this context – the strong protomagnetar wind acting shortly after birth. We also account for the effect of buoyancy forces on viscous dissipation at late times. Typically, we find that χ → 90° shortly after birth, then decreases towards 0° over hundreds of years. From observational indications that magnetars typically have small χ, we infer that these stars are subject to a stronger average exterior torque than radio pulsars, and that they were born spinning faster than ∼100–300 Hz. Our results allow us to make quantitative predictions for the gravitational and electromagnetic signals from a newborn rotating magnetar. We also comment briefly on the possible connection with periodic fast radio burst sources.
While many laboratory studies have focused on the short term effects of biochar addition to soil), there have been comparatively few tracing its longer term effects in the field. This study ...investigated the multiyear impact of biochar on crop performance and soil quality with specific emphasis on carbon (C) and nitrogen (N) cycling over a 3 y period. Biochar was added to an agricultural field at 0, 25 and 50tha−1 and planted with maize (year 1) and grass (years 2 and 3). Biochar addition affected plant performance in the grass crop with significant increases in foliar N (year 2) and above-ground biomass (year 3). Below-ground, biochar increased soil respiration, fungal and bacterial growth rate and turnover in year 2. This change coincided with a shift toward a bacterial dominated decomposer community, suggesting a decrease in the potential for microbially mediated C sequestration. Biochar did not affect dissolved organic C (DOC) and N (DON), NO3− or NH4+ pool sizes. Similarly, biochar addition had limited effects on the turnover of 14C-labelled SOC (plant litter), DOC (sugars and organic acids) and DON (amino acids) and no long term effect on N mineralization, NH3 volatilization, denitrification and NH4+ sorption. After 3 years in the field, the alkalinity associated with the biochar had been fully neutralized and biochar lost most of its cations (K, Na, Ca) but had built up an associated microbial community. We conclude that biochar addition to soil causes small and potentially transient changes in a temperate agroecosystem functioning. Importantly, many of the short-term effects of biochar on plant growth and soil behavior reported from laboratory studies were not observed in the field emphasizing the need for long term field trials to help inform agronomic management decisions involving biochar.
► Biochar induced temporary shifts in soil respiration and microbial community structure. ► Biochar induced only small changes in soil carbon and nitrogen cycling. ► Biochar had no observed negative effects on soil quality or crop production. ► Short term effects of biochar observed in the laboratory were not apparent in the field.
A significant proportion of the total nutrient in soil solution can be bound to organic molecules and these often constitute a major loss from soil to freshwater. Our purpose was to determine whether ...chemical extractants used for measuring inorganic N could also be used to quantify dissolved organic nitrogen (DON) and carbon (DOC) in soil. In a range of soils, DOC and DON were extracted with either distilled water or 2
M KCl and the amount recovered compared with that present in soil solution recovered by centrifugal-drainage. The recovery of DON and DOC from soil was highly dependent upon the method of extraction. Factors such as soil sampling strategy (number of samples over space and time), sample preparation (sieving and drying), soil storage, extraction temperature, shaking time, and soil-to-extractant volume ratio all significantly affected the amount of DOC and DON extracted from soil. To allow direct comparison between independent studies we therefore propose the introduction of a standardized extraction procedure: Replicate samples of unsieved, field-moist soil extracted as soon as possible after collection with distilled water, 0.5
M K
2SO
4 or 2
M KCl at a 1:5
w/v ratio for 1
h at 20
°C.
Rapid Response Teams (RRT) are specialised teams that review deteriorating ward patients in an attempt to prevent morbidity and mortality. Most studies have assessed the effect of implementing an RRT ...into a hospital. There is much less literature on the characteristics and outcomes of RRT patients themselves. This article reviews the epidemiology of adult RRT patients in Australia and proposes three models of RRT syndromes. The number of RRT calls varies considerably in Australian hospitals from 1.35 to 71.3/1000 hospital admissions. Common causes of RRT calls include sepsis, atrial fibrillation, seizures and pulmonary oedema. Approximately 20% of patients to whom an RRT has responded have more than one RRT call, and up to one-third have issues around end-of-life care. Calls are least common overnight. Between 10 to 25% of patients are admitted to a critical care area after the call. The in-hospital mortality for RRT patients is approximately 25% overall but only 15% in patients without a limitation of medical therapy. RRT syndromes can be conceptually described by the trigger for the call (e.g. hypotension) or the clinical condition causing the call (e.g. sepsis). Alternatively, the RRT call can be described by the major theme of the call: "end-of-life care", "requiring critical care" and "stable enough to initially remain on the ward". Based on these themes, education strategies and quality improvement initiatives may be developed to reduce the incidence of RRT calls, further improving patient outcome.
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