95 research outputs found
Recovering the unsigned photospheric magnetic field from Ca II K observations
We reassess the relationship between the photospheric magnetic field strength
and the Ca II K intensity for a variety of surface features as a function of
the position on the disc and the solar activity level. This relationship can be
used to recover the unsigned photospheric magnetic field from images recorded
in the core of Ca II K line. We have analysed 131 pairs of high-quality,
full-disc, near-co-temporal observations from SDO/HMI and Rome/PSPT spanning
half a solar cycle. To analytically describe the observationally-determined
relation, we considered three different functions: a power law with an offset,
a logarithmic function, and a power law function of the logarithm of the
magnetic flux density. We used the obtained relations to reconstruct maps of
the line-of-sight component of the unsigned magnetic field (unsigned
magnetograms) from Ca II K observations, which were then compared to the
original magnetograms. We find that both power-law functions represent the data
well, while the logarithmic function is good only for quiet periods. We see no
significant variation over the solar cycle or over the disc in the derived fit
parameters, independently of the function used. We find that errors in the
independent variable, usually not accounted for, introduce attenuation bias. To
address this, we binned the data with respect to the magnetic field strength
and Ca II K contrast separately and derived the relation for the bisector of
the two binned curves. The reconstructed unsigned magnetograms show good
agreement with the original ones. RMS differences are less than 90 G. The
results were unaffected by the stray-light correction of the SDO/HMI and
Rome/PSPT data. Our results imply that Ca~II~K observations, accurately
processed and calibrated, can be used to reconstruct unsigned magnetograms by
using the relations derived in our study.Comment: 18 pages, 22 figures, accepted in A&
Long-term changes in solar activity and irradiance
The Sun is the main energy source to Earth, and understanding its variability
is of direct relevance to climate studies. Measurements of total solar
irradiance exist since 1978, but this is too short compared to climate-relevant
time scales. Coming from a number of different instruments, these measurements
require a cross-calibration, which is not straightforward, and thus several
composite records have been created. All of them suggest a marginally
decreasing trend since 1996. Most composites also feature a weak decrease over
the entire period of observations, which is also seen in observations of the
solar surface magnetic field and is further supported by Ca II K data. Some
inconsistencies, however, remain and overall the magnitude and even the
presence of the long-term trend remain uncertain. Different models have been
developed, which are used to understand the irradiance variability over the
satellite period and to extend the records of solar irradiance back in time.
Differing in their methodologies, all models require proxies of solar magnetic
activity as input. The most widely used proxies are sunspot records and
cosmogenic isotope data on centennial and millennial time scale, respectively.
None of this, however, offers a sufficiently good, independent description of
the long-term evolution of faculae and network responsible for solar
brightening. This leads to uncertainty in the amplitude of the long-term
changes in solar irradiance. Here we review recent efforts to improve
irradiance reconstructions on time scales longer than the solar cycle and to
reduce the existing uncertainty in the magnitude of the long-term variability.
In particular, we highlight the potential of using 3D magnetohydrodynamical
simulations of the solar atmosphere as input to more physical irradiance models
and of historical full-disc Ca II K observations encrypting direct facular
information back to 1892.Comment: 17 pages, 8 figures, accepted for publication in JAST
In-situ Optimized Substrate Witness Plates: Ground Truth for Key Processes on the Moon and Other Planets
Future exploration efforts of the Moon, Mars and other bodies are poised to
focus heavily on persistent and sustainable survey and research efforts,
especially given the recent interest in a long-term sustainable human presence
at the Moon. Key to these efforts is understanding a number of important
processes on the lunar surface for both scientific and operational purposes. We
discuss the potential value of in-situ artificial substrate witness plates,
powerful tools that can supplement familiar remote sensing and sample
acquisition techniques and provide a sustainable way of monitoring processes in
key locations on planetary surfaces while maintaining a low environmental
footprint. These tools, which we call Biscuits, can use customized materials as
wide ranging as zircon-based spray coatings to metals potentially usable for
surface structures, to target specific processes/questions as part of a small,
passive witness plate that can be flexibly placed with respect to location and
total time duration. We examine and discuss unique case studies to show how
processes such as water presence/transport, presence and contamination of
biologically relevant molecules, solar activity related effects, and other
processes can be measured using Biscuits. Biscuits can yield key location
sensitive, time integrated measurements on these processes to inform scientific
understanding of the Moon and enable operational goals in lunar exploration.
While we specifically demonstrate this on a simulated traverse and for selected
examples, we stress all groups interested in planetary surfaces should consider
these adaptable, low footprint and highly informative tools for future
exploration.Comment: Accepted to Earth and Space Science, Will be updated upon publicatio
SDE2 integrates into the TIMELESS-TIPIN complex to protect stalled replication forks
Protecting replication fork integrity during DNA replication is essential for maintaining genome stability. Here, we report that SDE2, a PCNA-associated protein, plays a key role in maintaining active replication and counteracting replication stress by regulating the replication fork protection complex (FPC). SDE2 directly interacts with the FPC component TIMELESS (TIM) and enhances its stability, thereby aiding TIM localization to replication forks and the coordination of replisome progression. Like TIM deficiency, knockdown of SDE2 leads to impaired fork progression and stalled fork recovery, along with a failure to activate CHK1 phosphorylation. Moreover, loss of SDE2 or TIM results in an excessive MRE11-dependent degradation of reversed forks. Together, our study uncovers an essential role for SDE2 in maintaining genomic integrity by stabilizing the FPC and describes a new role for TIM in protecting stalled replication forks. We propose that TIM-mediated fork protection may represent a way to cooperate with BRCA-dependent fork stabilization. The fork protection complex (FPC), including the proteins TIMELESS and TIPIN, stabilizes the replisome to ensure unperturbed fork progression during DNA replication. Here the authors reveal that that SDE2, a PCNA-associated protein, plays an important role in maintaining active replication and protecting stalled forks by regulating the replication fork protection complex (FPC)
Understanding, treating, and renaming grandiose delusions : a qualitative study
Background
Grandiose delusions are arguably the most neglected psychotic experience in research.
Objectives
We aimed to discover from patients: whether grandiose delusions have harmful consequences; the psychological mechanisms that maintain them; and what help patients may want from clinical services.
Design
A qualitative interview design was used to explore patients’ experiences of grandiose delusions.
Method
Fifteen patients with past or present experiences of grandiose delusions who were attending psychiatric services were interviewed. Thematic analysis and grounded theory were used to analyse the data.
Results
Participants reported physical, sexual, social, occupational, and emotional harms from grandiose delusions. All patients described the grandiose belief as highly meaningful: it provided a sense of purpose, belonging, or self‐identity, or it made sense of unusual or difficult events. The meaning from the belief was not synonymous with extreme superiority or arrogance. The meaning obtained appeared to be a key driver of the persistence of the beliefs. Other maintenance factors were subjectively anomalous experiences (e.g., voices), symptoms of mania, fantasy elaboration, reasoning biases, and immersive behaviours. Participants described insufficient opportunities to talk about their grandiose beliefs and related experiences and were generally positive about the possibility of a psychological therapy.
Conclusions
We conclude that grandiosity is a psychologically rich experience, with a number of maintenance factors that may be amenable to a targeted psychological intervention. Importantly, the term ‘grandiose delusion’ is an imprecise description of the experience; we suggest ‘delusions of exceptionality’ may be a credible alternative.
Practitioner points
-Harm from grandiose delusions can occur across multiple domains (including physical, sexual, social, occupational, and emotional) and practitioners should assess accordingly.
-However, grandiose delusions are experienced by patients as highly meaningful: they provide a sense of purpose, belonging, or self‐identity, or make sense of unusual or difficult events.
-Possible psychological maintenance mechanisms that could be a target for intervention include the meaning of the belief, anomalous experiences, mania, fantasy elaboration, reasoning biases, and immersive behaviours.
-Patients are keen to have the opportunity to access talking therapies for this experience. Taking extra time to talk at times of distress, ‘going the extra mile’, and listening carefully can help to facilitate trust
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Potent acyl-CoA synthetase 10 inhibitors kill <i>Plasmodium falciparum</i> by disrupting triglyceride formation
Identifying how small molecules act to kill malaria parasites can lead to new chemically validated targets. By pressuring Plasmodium falciparum asexual blood stage parasites with three novel structurally-unrelated antimalarial compounds (MMV665924, MMV019719 and MMV897615), and performing whole-genome sequence analysis on resistant parasite lines, we identify multiple mutations in the P. falciparum acyl-CoA synthetase (ACS) genes PfACS10 (PF3D7_0525100, M300I, A268D/V, F427L) and PfACS11 (PF3D7_1238800, F387V, D648Y, and E668K). Allelic replacement and thermal proteome profiling validates PfACS10 as a target of these compounds. We demonstrate that this protein is essential for parasite growth by conditional knockdown and observe increased compound susceptibility upon reduced expression. Inhibition of PfACS10 leads to a reduction in triacylglycerols and a buildup of its lipid precursors, providing key insights into its function. Analysis of the PfACS11 gene and its mutations point to a role in mediating resistance via decreased protein stability
Thresholds for adding degraded tropical forest to the conservation estate
Logged and disturbed forests are often viewed as degraded and depauperate environments compared with primary forest. However, they are dynamic ecosystems1 that provide refugia for large amounts of biodiversity2, 3, so we cannot afford to underestimate their conservation value4. Here we present empirically defined thresholds for categorizing the conservation value of logged forests, using one of the most comprehensive assessments of taxon responses to habitat degradation in any tropical forest environment. We analysed the impact of logging intensity on the individual occurrence patterns of 1,681 taxa belonging to 86 taxonomic orders and 126 functional groups in Sabah, Malaysia. Our results demonstrate the existence of two conservation-relevant thresholds. First, lightly logged forests (68%) of their biomass removed, and these are likely to require more expensive measures to recover their biodiversity value. Overall, our data confirm that primary forests are irreplaceable5, but they also reinforce the message that logged forests retain considerable conservation value that should not be overlooked
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