Nova shells. II - Calibration of the distance scale using novae

Eight new spatially resolved nova shells have been found by imaging with a digital detector through a narrow Hα filter, and two old novae have been recovered. The 11 novae with the best determined maximum luminosities at outburst of the sample of 21 novae with reliable distances are used to derive a M_v(max)-rate of decline relationship. These 11 objects have a mean M_v 15 days past maximum of —5.60 ± 0.45 mag. If I assume that M_v(15) is in fact constant, as is suggested by the theory, then for the full sample of 21 objects I find M_v(max, corr) = —10.70( ±0.30) + 2.41( ±0.23) log (t_2), where t_2 is the time in days to decline 2 mag below maximum light. Having removed all obvious sources of observational error, I deduce that the dispersion in nova outburst luminosity for a fixed rate of decline is 0.45 mag. Previously published surveys of novae in 31 are used to redetermine the distance to that galaxy

External pressures on teaching: three years on

n August 2001, I wrote an information article called ‘External Pressures on Teaching’, which was published in the then PRSLTSN Journal, 1.2, Winter 2002, pp. 98–129. It is now time to update that article, and to add a number of subsequent developments. However, the original article, which explains the logic of the various QAA initiatives, is still valid apart from some points of detail that I shall highlight here. It is available on our website at: http://prs.heacademy.ac.uk/publications/discourse/winter2002.pd

Revealing the Molecular Structure and the Transport Mechanism at the Base of Primary Cilia Using Superresolution STED Microscopy

The primary cilium is an organelle that serves as a signaling center of the cell and is involved in the hedgehog signaling, cAMP pathway, Wnt pathways, etc. Ciliary function relies on the transportation of molecules between the primary cilium and the cell, which is facilitated by intraflagellar transport (IFT). IFT88, one of the important IFT proteins in complex B, is known to play a role in the formation and maintenance of cilia in various types of organisms. The ciliary transition zone (TZ), which is part of the gating apparatus at the ciliary base, is home to a large number of ciliopathy molecules. Recent studies have identified important regulating elements for TZ gating in cilia. However, the architecture of the TZ region and its arrangement relative to intraflagellar transport (IFT) proteins remain largely unknown, hindering the mechanistic understanding of the regulation processes. One of the major challenges comes from the tiny volume at the ciliary base packed with numerous proteins, with the diameter of the TZ close to the diffraction limit of conventional microscopes. Using a series of stimulated emission depletion (STED) superresolution images mapped to electron microscopy images, we analyzed the structural organization of the ciliary base. Subdiffraction imaging of TZ components defines novel geometric distributions of RPGRIP1L, MKS1, CEP290, TCTN2 and TMEM67, shedding light on their roles in TZ structure, assembly, and function. We found TCTN2 at the outmost periphery of the TZ close to the ciliary membrane, with a 227±18 nm diameter. TMEM67 was adjacent to TCTN2, with a 205±20 nm diameter. RPGRIP1L was localized toward the axoneme at the same axial level as TCTN2 and TMEM67, with a 165±8 nm diameter. MKS1 was situated between TMEM67 and RPGRIP1L, with an 186±21 nm diameter. Surprisingly, CEP290 was localized at the proximal side of the TZ close to the distal end of the centrin-labeled basal body. The lateral width was unexpectedly close to the width of the basal body, distant from the potential Y-links region of the TZ. Moreover, IFT88 was intriguingly distributed in two distinct patterns, forming three puncta or a Y shape at the ciliary base found in human retinal pigment epithelial cells (RPE), human fibroblasts (HFF), mouse inner medullary collecting duct (IMCD) cells and mouse embryonic fibroblasts (MEFs). We hypothesize that the two distribution states of IFT88 correspond to the open and closed gating states of the TZ, where IFT particles aggregate to form three puncta when the gate is closed, and move to form the branches of the Y-shape pattern when the gate is open. Two reservoirs of IFT particles, correlating with phases of ciliary growth, were localized relative to the internal structure of the TZ. These subdiffraction images reveal unprecedented architectural details of the TZ, providing a basic structural framework for future functional studies. To visualize the dynamic movement of IFT particles within primary cilia, we further conducted superresolution live-cell imaging of IFT88 fused to EYFP in IMCD cells. Our findings, in particular, show IFT88 particles pass through the TZ at a reduced speed by approximately 50%, implying the gating mechanism is involved at this region to slow down IFT trafficking. Finally, we report the distinct transport pathways of IFT88 and Smo (Smoothened), an essential player to hedgehog signaling, to support our hypothesis that two proteins are transported in different mechanisms at the ciliary base, based on dual-color superresolution imaging

Analysis of mesoscale convective system initiations in the United States Corn Belt in the warm season of the years 1979 to 2013

Mesoscale Convective Systems (MCSs) produce the majority of the precipitation over the area east of the United States’ Rocky Mountains. These systems are responsible for the majority of the flash flooding and severe weather, which can have a significant impact on crops. MCSs are vitally important in crop growing areas and, in particular, the Corn Belt where almost half of the World’s corn supply is produced. Studying the changes in MCS initiation could lead to better prediction of corn yields. For this study, the warm season (April-September) MCS initiations over the United States Corn Belt are analyzed to determine significant MCS initiation conditions when compared to cases where no initiation occurred in the years 1979 to 2013. The Corn Belt is defined as Kansas, Nebraska, South Dakota, North Dakota, Minnesota, Iowa, Missouri, Illinois, Indiana, and Ohio. Changes in MCS initiation by initiation hour, month, half warm season, year, decade, and half of the database are also examined to determine what fluctuations occurred throughout the database. MCS initiation activity is studied because of the shortage of available literature. To determine the changes in MCS initiation, significance testing and logistic regressions were analyzed for the six hours prior to initiation through the three hours after initiation. For select time periods, a Bayes’ Theorem application was also completed. The statistical analyses, when coupled with meteorology, indicate the majority of the changes in MCS initiation can be attributed to the rise in global/regional temperatures. A large scale analysis, accomplished with spatial statistics, was also completed in the form to an intensity/cluster analysis and a teleconnection pattern analysis. The intensity/cluster analysis shows that there is clustering of the MCS initiation locations over the Corn Belt with MCS initiation locations particularly concentrated to Nebraska, Kansas, Missouri, and Iowa. For the teleconnection pattern analysis, each of the six teleconnection patterns studied do have an effect on initiation with the Pacific-North American Pattern and the West Pacific Pattern having the most profound effect. From this study, it can be concluded that MCS initiations are affected by climate change and specific teleconnection patterns

SoC Test: Trends and Recent Standards

The well-known approaching test cost crisis, where semiconductor test costs begin to approach or exceed manufacturing costs has led test engineers to apply new solutions to the problem of testing System-On-Chip (SoC) designs containing multiple IP (Intellectual Property) cores. While it is not yet possible to apply generic test architectures to an IP core within a SoC, the emergence of a number of similar approaches, and the release of new industry standards, such as IEEE 1500 and IEEE 1450.6, may begin to change this situation. This paper looks at these standards and at some techniques currently used by SoC test engineers. An extensive reference list is included, reflecting the purpose of this publication as a review paper

Public preferences for internet surveillance, data retention and privacy enhancing services: evidence from a pan-European study

This paper examines public preferences regarding privacy implications of internet surveillance. The study was based on a pan-European survey and included a stated preference discrete choice experiment (SPDCE) involving the choice of an Internet Service Provider (ISP) offering varying levels of storage, access and sharing of internet activity, continuous surveillance and privacy enhancing technologies. The survey obtained 16,463 individual responses across the European Union's 27 member-states1. Respondents expressed highest levels of concern about: Internet facilitated crime, namely using the internet to share and publish child pornography (68.2%); individual data protection and security threats – i.e., personal information not being handled in a legitimate way (62%); computer viruses (61.4%) and finally the theft of financial data or identity (61.4%). Such levels of concern affect trust in the Internet: 27.7% of respondents trusted websites for information exchange and a similar figure, 30.7% reported they trust websites for business transactions. Given this context, following our analysis of preferences, on average, respondents were more likely to choose an ISP that would not store any internet activity, would retain any data for up to 1 month and would not share data with anyone else. Interestingly, respondents did recognise the potential benefit for continuous state-surveillance (by the police), but only under an appropriate accountable legal basis. Also, respondents were in favour of an array of privacy enhancing technologies that would enhance their privacy when using the Internet. Finally, the analysis shows that in some cases, significant differences in preferences across countries and socio-economic characteristics suggest that individual privacy-preferences do vary across cultural/national settings, age, gender and education level

pyFIT3D and pyPipe3D -- The new version of the Integral Field Spectroscopy data analysis pipeline

We present a new version of the FIT3D and Pipe3D codes, two packages to derive properties of the stellar populations and the ionized emission lines from optical spectroscopy and integral field spectroscopy data respectively. The new codes have been fully transcribed to Python from the original Perl and C versions, modifying the algorithms when needed to make use of the unique capabilities of this language with the main goals of (1) respecting as much as possible the original philosophy of the algorithms, (2) maintaining a full compatibility with the original version in terms of the format of the required input and produced output files, and (3) improving the efficiency and accuracy of the algorithms, and solving known (and newly discovered) bugs. The complete package is freely distributed, with an available repository online. pyFIT3D and pyPipe3D are fully tested with data of the most recent IFS data surveys and compilations (e.g. CALIFA, MaNGA, SAMI and AMUSING++), and confronted with simulations. We describe here the code, its new implementation, its accuracy in recovering the parameters based on simulations, and a showcase of its implementation on a particular dataset.Comment: New Astronomy - 29 pages, 19 figures - Received on 7 Dec 2021 - Accepted for publication on 8 Jul 202