A bin-microphysics parcel model investigation of secondary ice formation in an idealised shallow convective cloud

We provide the first systematic study of ice formation in idealised shallow clouds from collisions of supercooled water drops with ice particles (&lsquo;mode 2&rsquo;). Using the University of Manchester bin-microphysics parcel model, we investigated the sensitivity of ice formation due to mode 2 for a wide range of parameters: aerosol particle size distribution, updraft speed, cloud base temperature, cloud depth, ice-nucleating particle concentration and freezing fraction of mode 2. We provide context to our results with other secondary ice production mechanisms as single mechanisms and combinations (rime-splintering, spherical freezing fragmentation of drops [&lsquo;mode 1&rsquo;] and ice-ice collisions). There was a significant sensitivity to aerosol particle size distribution when updraft speeds were low (0.5 m s&minus;1); secondary ice formation did not occur when the aerosol particle size distribution mimicked polluted environments. Where secondary ice formation did occur in simulated clouds, significant ice formation in the shallower clouds (1.3 km deep) was due to mode 2 or a combination which included mode 2. The deeper clouds (2.4 km deep) also had significant contributions from rime-splintering or ice-ice collisions SIP mechanisms. While simulations with cloud base temperatures of 7 &deg;C were relatively insensitive to ice-nucleating particle concentrations, there was a sensitivity in simulations cloud base temperatures of 0 &deg;C. Increasing the ice-nucleating particle concentration delayed ice formation. Our results suggest that collisions of supercooled water drops with ice particles may be a significant ice formation mechanism within shallow convective clouds where rime-splintering is not active.</p

The Evolving Menace of Ransomware: A Comparative Analysis of Pre-pandemic and Mid-pandemic Attacks

Drawing upon direct interviews and secondary sources, this paper presents a qualitative comparative analysis of thirty-nine ransomware attacks, twenty-six of which occurred shortly before the outbreak of the COVID-19 pandemic and thirteen of which took place during the pandemic. The research objective was to gain an understanding of how ransomware attacks changed tactics across this period. Using inductive content analysis, a number of key themes emerged, namely: (1) ransomware attackers have adopted more sinister tactics and now commit multiple crimes to maximise their return, (2) the expanded attack surface caused by employees working from home has greatly aggravated the risk of malicious intrusion, (3) the preferred attack vectors have changed, with phishing and VPN exploits now to the fore, (4) failure to adapt common business processes from off-line to on-line interaction has created vulnerabilities, (5) the ongoing laissez-faire attitude towards cybersecurity and lack of preparedness continues to be a substantial problem, and (6) ransomware attacks now pose potentially severe consequences for individuals, whose personal data has become a central part of the game. Recommendations are proposed to address these issues

NASA Space applications of high-temperature superconductors

The application of superconducting technology in space has been limited by the requirement of cooling to near liquid helium temperatures. The only means of obtaining these temperatures has been with cryogenic fluids which severely limit mission lifetime. The development of materials with superconducting transition temperatures above 77 K has made superconducting technology more attractive and feasible for employment in aerospace systems. Here, potential applications of high temperature superconducting technology in cryocoolers, remote sensing, communications, and power systems are discussed

Using laboratory and field measurements to constrain a single habit shortwave optical parameterization for cirrus

A single habit parameterization for the shortwave optical properties of cirrus is presented. The parameterization utilizes a hollow particle geometry, with stepped internal cavities as identified in laboratory and field studies. This particular habit was chosen as both experimental and theoretical results show that the particle exhibits lower asymmetry parameters when compared to solid crystals of the same aspect ratio. The aspect ratio of the particle was varied as a function of maximum dimension, D, in order to adhere to the same physical relationships assumed in the microphysical scheme in a configuration of the Met Office atmosphere-only global model, concerning particle mass, size and effective density. Single scattering properties were then computed using T-Matrix, Ray Tracing with Diffraction on Facets (RTDF) and Ray Tracing (RT) for small, medium, and large size parameters respectively. The scattering properties were integrated over 28 particle size distributions as used in the microphysical scheme. The fits were then parameterized as simple functions of Ice Water Content (IWC) for 6 shortwave bands. The parameterization was implemented into the GA6 configuration of the Met Office Unified Model along with the current operational long-wave parameterization. The GA6 configuration is used to simulate the annual twenty-year short-wave (SW) fluxes at top-of-atmosphere (TOA) and also the temperature and humidity structure of the atmosphere. The parameterization presented here is compared against the current operational model and a more recent habit mixture model

Pixel-z: Studying Substructure and Stellar Populations in Galaxies out to z~3 using Pixel Colors I. Systematics

We perform a pixel-by-pixel analysis of 467 galaxies in the GOODS-VIMOS survey to study systematic effects in extracting properties of stellar populations (age, dust, metallicity and SFR) from pixel colors using the pixel-z method. The systematics studied include the effect of the input stellar population synthesis model, passband limitations and differences between individual SED fits to pixels and global SED-fitting to a galaxy's colors. We find that with optical-only colors, the systematic errors due to differences among the models are well constrained. The largest impact on the age and SFR e-folding time estimates in the pixels arises from differences between the Maraston models and the Bruzual&Charlot models, when optical colors are used. This results in systematic differences larger than the 2{\sigma} uncertainties in over 10 percent of all pixels in the galaxy sample. The effect of restricting the available passbands is more severe. In 26 percent of pixels in the full sample, passband limitations result in systematic biases in the age estimates which are larger than the 2{\sigma} uncertainties. Systematic effects from model differences are reexamined using Near-IR colors for a subsample of 46 galaxies in the GOODS-NICMOS survey. For z > 1, the observed optical/NIR colors span the rest frame UV-optical SED, and the use of different models does not significantly bias the estimates of the stellar population parameters compared to using optical-only colors. We then illustrate how pixel-z can be applied robustly to make detailed studies of substructure in high redshift galaxies such as (a) radial gradients of age, SFR, sSFR and dust and (b) the distribution of these properties within subcomponents such as spiral arms and clumps. Finally, we show preliminary results from the CANDELS survey illustrating how the new HST/WFC3 data can be exploited to probe substructure in z~1-3 galaxies.Comment: 37 pages, 21 figures, submitted to Ap

Characterisation of the mode of action of Aurodox, a Type III secretion system inhibitor from Streptomyces goldiniensis

Recent work has demonstrated that the polyketide natural product Aurodox, from Streptomyces goldiniensis is able to block the pathogenesis of the murine pathogen Citrobacter rodentium. In this work we aimed to aimed gain a better understanding of the mechanism of action of the compound. We show that Aurodox downregulates the expression of the Type Three Secretion Systems of enteropathogenic and enterohaemorhagic Escherichia coli. Furthermore, we have used transcriptomic analysis to show that Aurodox inhibits the expression at the transcriptional level by repressing the master regulator, ler. Our data support a model in which Aurodox acts upstream of ler and not directly on the secretion system itself. Finally, we have shown that Aurodox, unlike some traditional antibiotics, does not induce expression of RecA, which is essential for the production of Shiga toxin. We propose that these properties nominate Aurodox as a promising anti-virulence therapy for the treatment of these infections

B-mode ultrasound assessment of pupillary function: feasibility, reliability and normal values

PURPOSE: To evaluate B-mode ultrasound as a novel method for the examination of pupillary function and to provide normal values for the pupillary reflex as assessed by B-mode ultrasound. METHODS: 100 subjects (49 female, 51 male, mean [range] age 51 [18-80 years]) with no history of ophthalmologic disease, no clinically detectable pupillary defects, and corrected visual acuity >= 0.8 were included in this prospective observational study. B-mode ultrasound was performed with the subjects eyes closed using an Esaote-Mylab25 system according to current guidelines for orbital insonation. A standardized light stimulus was applied. RESULTS: The mean +/- standard deviation left and right pupillary diameters (PD) at rest were 4.7 +/- 0.8 and 4.5 +/- 0.8 mm. Following an ipsilateral light stimulus (Lstim), left and right constricted PD were 2.8 +/- 0.6 and 2.7 +/- 0.6 mm. Following a contralateral Lstim, left and right constricted PD were 2.7 +/- 0.6 and 2.6 +/- 0.5 mm. Left and right pupillary constriction time (PCT) following ipsilateral Lstim were 970 +/- 261.6 and 967 +/- 220 ms. Left and right PCT following a contralateral Lstim were 993.8 +/- 192.6 and 963 +/- 189.4 ms. Patient age was inversely correlated with PD at rest and with PD after ipsilateral and contralateral Lstim (all p<0.001), but not with PCT. CONCLUSIONS: B-mode ultrasound is a simple, rapid and objective method for the quantitative assessment of pupillary function, which may prove useful in a variety of settings where eyelid retraction is impeded or an infrared pupillometry device is unavailable

miR-1-5p targets TGF-βR1 and is suppressed in the hypertrophying hearts of rats with pulmonary arterial hypertension.

The microRNA miR-1 is an important regulator of muscle phenotype including cardiac muscle. Down-regulation of miR-1 has been shown to occur in left ventricular hypertrophy but its contribution to right ventricular hypertrophy in pulmonary arterial hypertension are not known. Previous studies have suggested that miR-1 may suppress transforming growth factor-beta (TGF-β) signalling, an important pro-hypertrophic pathway but only indirect mechanisms of regulation have been identified. We identified the TGF-β type 1 receptor (TGF-βR1) as a putative miR-1 target. We therefore hypothesized that miR-1 and TGF-βR1 expression would be inversely correlated in hypertrophying right ventricle of rats with pulmonary arterial hypertension and that miR-1 would inhibit TGF-β signalling by targeting TGF-βR1 expression. Quantification of miR-1 and TGF-βR1 in rats treated with monocrotaline to induce pulmonary arterial hypertension showed appropriate changes in miR-1 and TGF-βR1 expression in the hypertrophying right ventricle. A miR-1-mimic reduced enhanced green fluorescent protein expression from a reporter vector containing the TGF-βR1 3'- untranslated region and knocked down endogenous TGF-βR1. Lastly, miR-1 reduced TGF-β activation of a (mothers against decapentaplegic homolog) SMAD2/3-dependent reporter. Taken together, these data suggest that miR-1 targets TGF-βR1 and reduces TGF-β signalling, so a reduction in miR-1 expression may increase TGF-β signalling and contribute to cardiac hypertrophy