217 research outputs found
An Ultra-High Time Resolution Cosmic-Ray Detection Mode for the Murchison Widefield Array
The radio-wavelength detection of extensive air showers (EASs) initiated by cosmic-ray interactions in the Earth's atmosphere is a promising technique for investigating the origin of these particles and the physics of their interactions. The Low-frequency Array (LOFAR) and the Owens Valley Long Wavelength Array (OVRO-LWA) have both demonstrated that the dense cores of low-frequency radio telescope arrays yield detailed information on the radiation ground pattern, which can be used to reconstruct key EAS properties and infer the primary cosmic-ray composition. Here, we demonstrate a new observation mode of the Murchison Widefield Array (MWA), tailored to the observation of the sub-microsecond coherent bursts of radiation produced by EAS. We first show how an aggregate 30.72MHz bandwidth (3072×10kHz frequency channels) recorded at 0.1ms resolution with the MWA's voltage capture system (VCS) can be synthesized back to the full bandwidth Nyquist resolution of 16.3ns. This process, which involves "inverting"two sets of polyphase filterbanks, retains 90.5% of the signal-to-noise of a cosmic-ray signal. We then demonstrate the timing and positional accuracy of this mode by resolving the location of a calibrator pulse to within 5m. Finally, preliminary observations show that the rate of nanosecond radio-frequency interference (RFI) events is 0.1Hz, much lower than that found at the sites of other radio telescopes that study cosmic rays. We conclude that the identification of cosmic rays at the MWA, and hence with the low-frequency component of the Square Kilometre Array, is feasible with minimal loss of efficiency due to RFI
Paternal effects in a wild-type zebrafish implicate a role of sperm-derived small RNAs
While the importance of maternal effects has long been appreciated, a growing body
of evidence now points to the paternal environment having an important influence
on offspring phenotype. Indeed, research on rodent models suggests that paternal
stress leaves an imprint on the behaviour and physiology of offspring via nonge netic information carried in the spermatozoa; however, fish have been understudied
with regard to these sperm-mediated effects. Here, we investigated whether the ze brafish was subjected to heritable influences of paternal stress by exposing males to
stressors (conspecific-derived alarm cue, chasing and bright light) before mating and
assessing the behavioural and endocrine responses of their offspring, including their
behavioural response to conspecific-derived alarm cue. We found that after males are
exposed to stress, their larval offspring show weakened responses to stressors. Small
RNA sequencing subsequently revealed that the levels of several small noncoding
RNAs, including microRNAs, PIWI-interacting RNAs and tRNA-derived small RNAs,
were altered in the spermatozoa of stressed fathers, suggesting that stress-induced
alterations to the spermatozoal RNA landscape may contribute to shaping offspring
phenotype. The work demonstrates that paternal stress should not be overlooked as
a source of phenotypic variation and that spermatozoal small RNAs may be important
intergenerational messengers in fish
Spectrochemical analysis of sycamore (Acer pseudoplatanus) leaves for environmental health monitoring
Terrestrial plants are ideal sentinels of environmental pollution, due to their sedentary nature, abundance and sensitivity to atmospheric changes. However, reliable and sensitive biomarkers of exposure have hitherto been difficult to characterise. Biospectroscopy offers a novel approach to the derivation of biomarkers in the form of discrete molecular alterations detectable within a biochemical fingerprint. We investigated the application of this approach for the identification of biomarkers for pollution exposure using the common sycamore (Acer pseudoplatanus) as a sentinel species. Attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopy was used to interrogate leaf tissue collected from three sites exposed to different levels of vehicle exhaust emissions. Following multivariate analysis of acquired spectra, significant biochemical alterations were detected between comparable leaves from different sites that may constitute putative biomarkers for pollution-induced stress. These included differences in carbohydrate and nucleic acid conformations, which may be indicative of sub-lethal exposure effects. We also observed several corresponding spectral alterations in both the leaves of A. pseudoplatanus exposed to ozone pollution under controlled environmental conditions and in leaves infected with the fungal pathogen Rhytisma acerinum, indicating that some stress-induced changes are conserved between different stress signatures. These similarities may be indicative of stress-induced reactive oxygen species (ROS) generation, although further work is needed to verify the precise identity of infrared biomarkers and to identify those that are specific to pollution exposure. Taken together, our data clearly demonstrate that biospectroscopy presents an effective toolkit for the utilisation of higher plants, such as A. pseudoplatanus, as sentinels of environmental pollution
Spermatozoa, acts as an external cue and alters the cargo and production of the extracellular vesicles derived from oviductal epithelial cells in vitro.
The oviduct provides optimum physiological and biochemical milieu essential for successful fertilization, early embryo development and facilitates functional maturation of spermatozoa. A study has revealed that spermatozoa alters the gene expression in bovine oviductal epithelial cells (BOECs) remotely via bio-active particles, thus acting as a cue to the oviduct prior to their arrival. However, very little attention has been paid to the question of whether spermatozoa could alter the cargo of extracellular vesicles (EVs) derived from BOECs. Therefore, the aim of this study was to investigate the alterations in small non-coding RNAs in EVs cargo derived from BOECs when incubated with spermatozoa in contact and non-contact co-culture models. After 4 h of incubation the EVs were isolated from the conditioned media, followed by small non-coding sequencing of the BOEC derived EVs. Our results revealed that EVs from both co-culture models contained distinct cargo in form of miRNA, fragmented mRNA versus control. The pathway enrichment analysis revealed that EV miRNA from direct co-culture were involved in the biological processes associated with phagocytosis, macroautophagy, placenta development, cellular responses to TNF and FGF. The mRNA fragments also varied within the different groups and mapped to the exonic regions of the transcriptome providing vital insights regarding the changes in cellular transcriptome on the arrival of spermatozoa. The findings of this study suggest that spermatozoa, in contact as well as remotely, alter the EV cargo of female reproductive tract epithelial cells which might be playing an essential role in pre and post-fertilization events
Why do banks promise to pay par on demand?
We survey the theories of why banks promise to pay par on demand and examine evidence about
the conditions under which banks have promised to pay the par value of deposits and banknotes on
demand when holding only fractional reserves. The theoretical literature can be broadly divided into four
strands: liquidity provision, asymmetric information, legal restrictions, and a medium of exchange. We
assume that it is not zero cost to make a promise to redeem a liability at par value on demand. If so, then
the conditions in the theories that result in par redemption are possible explanations of why banks
promise to pay par on demand. If the explanation based on customers’ demand for liquidity is correct,
payment of deposits at par will be promised when banks hold assets that are illiquid in the short run. If
the asymmetric-information explanation based on the difficulty of valuing assets is correct, the
marketability of banks’ assets determines whether banks promise to pay par. If the legal restrictions
explanation of par redemption is correct, banks will not promise to pay par if they are not required to do
so. If the transaction explanation is correct, banks will promise to pay par value only if the deposits are
used in transactions. After the survey of the theoretical literature, we examine the history of banking in
several countries in different eras: fourth-century Athens, medieval Italy, Japan, and free banking and
money market mutual funds in the United States. We find that all of the theories can explain some of the
observed banking arrangements, and none explain all of them
Building a community of inquiry for pluralistic practice
Pluralism offers a means of recognising the value of multiple voices and perspectives and has emerged as an increasingly significant guiding framework for making sense of the complexity and diversity of contemporary social life. Pluralistic Practice is an open access journal created with the intention of supporting the development of a global community of inquiry within which practitioners, communities, and citizens can share knowledge, experience, and evidence around the challenges and benefits of working pluralistically to facilitate individual and collective well-being, solidarity, and justice. The present article offers an introduction to how the journal will operate and what it hopes to achieve and extends an invitation to be part of this endeavour
Building a community of inquiry for pluralistic practice
Pluralism offers a means of recognising the value of multiple voices and perspectives and has emerged as an increasingly significant guiding framework for making sense of the complexity and diversity of contemporary social life. Pluralistic Practice is an open access journal created with the intention of supporting the development of a global community of inquiry within which practitioners, communities, and citizens can share knowledge, experience, and evidence around the challenges and benefits of working pluralistically to facilitate individual and collective well-being, solidarity, and justice. The present article offers an introduction to how the journal will operate and what it hopes to achieve and extends an invitation to be part of this endeavour
Building a Community of Inquiry for Pluralistic Practice
Copyright (c) 2024 Pluralistic Practice JournalPluralism offers a means of recognising the value of multiple voices and perspectives and has emerged as an increasingly significant guiding framework for making sense of the complexity and diversity of contemporary social life. Pluralistic Practice is an open access journal created with the intention of supporting the development of a global community of inquiry within which practitioners, communities, and citizens can share knowledge, experience, and evidence around the challenges and benefits of working pluralistically to facilitate individual and collective well-being, solidarity, and justice. The present article offers an introduction to how the journal will operate and what it hopes to achieve and extends an invitation to be part of this
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