Harry Potter and the Meaning of Death

The paper reviews how J.K. Rowling is able to examine death in the Harry Potter book series. In the first part of the text the author touches on the deaths of Harry\u27s parents and the scarring that Harry receives from that, as well as an examination of how the deaths of others, from close friends to acquaintances, have affected Harry, specifically pertaining to his personal responsibility for them and also his grieving process. The paper also goes into how Voldemort\u27s inability to feel love, paired with his fear of dying, have pushed his quest for immortality (using Horcruxes). Harry\u27s mastery of death (using the Hallows), his willingness to accept death, and his sense of love and sacrifice for his friends is what enables him to finally defeat Voldemort. The main message is that the Harry Potter books are great entertainment, but their underlying philosophy on death creates a depth that Rowling wants us to learn from: death is a part of life, and seeking love and friendship is much more important than worrying about death

SKA Engineering Change Proposal: Gridded Visibilities to Enable Precision Cosmology with Radio Weak Lensing

This document was submitted as supporting material to an Engineering Change Proposal (ECP) for the Square Kilometre Array (SKA). This ECP requests gridded visibilities as an extra imaging data product from the SKA, in order to enable bespoke analysis techniques to measure source morphologies to the accuracy necessary for precision cosmology with radio weak lensing. We also discuss the properties of an SKA weak lensing data set and potential overlaps with other cosmology science goals.Comment: Comments welcome. 4 pages, 3 figures. Progress can be tracked at the SKA ECP register https://skaoffice.atlassian.net/wiki/display/EP/ECP+Registe

Three-point bridge calibration with one resistor

Method calibrates transducer bridge curing unbalanced condition and line resistance errors are negligible. Series resistance method can be automated easily and controlled by 2-bit information source which provide 4 states for switches

Radio-Optical Galaxy Shape Correlations in the COSMOS Field

We investigate the correlations in galaxy shapes between optical and radio wavelengths using archival observations of the COSMOS field. Cross-correlation studies between different wavebands will become increasingly important for precision cosmology as future large surveys may be dominated by systematic rather than statistical errors. In the case of weak lensing, galaxy shapes must be measured to extraordinary accuracy (shear systematics of $< 0.01\%$) in order to achieve good constraints on dark energy parameters. By using shape information from overlapping surveys in optical and radio bands, robustness to systematics may be significantly improved without loss of constraining power. Here we use HST-ACS optical data, VLA radio data, and extensive simulations to investigate both our ability to make precision measurements of source shapes from realistic radio data, and to constrain the intrinsic astrophysical scatter between the shapes of galaxies as measured in the optical and radio wavebands. By producing a new image from the VLA-COSMOS L-band radio visibility data that is well suited to galaxy shape measurements, we are able to extract precise measurements of galaxy position angles. Comparing to corresponding measurements from the HST optical image, we set a lower limit on the intrinsic astrophysical scatter in position angles, between the optical and radio bands, of $\sigma_\alpha > 0.212\pi$ radians (or $38.2^{\circ}$) at a $95\%$ confidence level.Comment: 17 pages, 13 figure, 5 tables. Updated to match published version with a number of typographical correction

The relationship between EUV dimming and coronal mass ejections

Aims. There have been many studies of extreme-ultraviolet (EUV) dimming in association with coronal mass ejection (CME) onsets. However, there has never been a thorough statistical study of this association, covering appropriate temperature ranges. Thus, we make use of a large campaign database utilising the Coronal Diagnostic Spectrometer (CDS) and the Large Angle and Spectrometric COronagraph (LASCO) both on the SOlar and Heliospheric Observatory (SOHO) to associate dimming events detected at 1 and 2 million K with CME activity. The aim is to confirm whether the dimming-CME association is real or not. This in turn will confirm whether special attention should be paid to the EUV dimming in the pre-eruption and eruption periods to study the CME onset process itself. Methods. The CDS CME onset campaign data for Mg IX and FE XVI observations on the solar limb are used to compare to LASCO event lists over a period from 1998 to 2005. Dimming events are identified and the physical extent explored, whilst comparing the events to overlying CME activity. Results. For the identified dimming regions we have shown strong associations with CME onsets, with up to 55% of the dimming events being associated with CME activity. This is compared to the random case where up to 47% of the dimming regions are expected to be associated with CMEs. We have also shown that up to 84% of CMEs associated with our data can be tracked back to dimming regions. This compares to a random case of up to 58%. Conclusions. These results confirm the CME-EUV dimming association, using a statistical analysis for the first time. We discuss the repercussions for the study of CME onsets, i.e. analysis of the dimming regions and the periods up to such dimming may be key to understanding the pre-CME onset plasma processes. The results stress that one emission line may not be sufficient for associating dimming regions with CMEs

Radio-Optical Galaxy Shape and Shear Correlations in the COSMOS Field using 3 GHz VLA Observations

We present a weak lensing analysis of the 3 GHz VLA radio survey of the COSMOS field, which we correlate with overlapping HST-ACS optical observations using both intrinsic galaxy shape and cosmic shear correlation statistics. After cross-matching sources between the two catalogues, we measure the correlations of galaxy position angles and find a Pearson correlation coefficient of $0.14 \pm 0.03$. This is a marked improvement from previous studies which found very weak, or non-existent correlations, and gives insight into the emission processes of radio and optical galaxies. We also extract power spectra of averaged galaxy ellipticities (the primary observable for cosmic shear) from the two catalogues, and produce optical-optical, radio-optical and radio-radio spectra. The optical-optical auto-power spectrum was measured to a detection significance of 9.80$\sigma$ and is consistent with previous observations of the same field. For radio spectra (which we do not calibrate, given the unknown nature of their systematics), although we do not detect significant radio-optical (1.50$\sigma$) or radio-radio (1.45$\sigma$) $E$-mode power spectra, we do find the $E$-mode spectra to be more consistent with the shear signal expected from previous studies than with a null signal, and vice versa for $B$-mode and $EB$ cross-correlation spectra. Our results give promise that future radio weak lensing surveys with larger source number densities over larger areas will have the capability to measure significant weak lensing signals.Comment: 19 pages, 17 figures, accepted for publication in MNRA

The density and mass distribution of meteoritic bodies in the neighborhood of the Earth's orbit

A study of the frequency of meteorite falls in areas which have been highly populated throughout the last century indicates that the average rate of fall of meteorites on the earth probably lies between 0.32 and 1.0 falls/year 10^6 km^2. The frequency of fall as a function of type and mass has been studied, and it is shown that the distribution curves for stones and irons have similar shapes. The curves are also remarkably similar to those observed for asteroids. The observed relationships are used to calculate the impact frequency of meteoritic particles upon the earth and moon as a function of their size

SKA Weak Lensing III: Added Value of Multi-Wavelength Synergies for the Mitigation of Systematics

In this third paper of a series on radio weak lensing for cosmology with the Square Kilometre Array, we scrutinise synergies between cosmic shear measurements in the radio and optical/near-IR bands for mitigating systematic effects. We focus on three main classes of systematics: (i) experimental systematic errors in the observed shear; (ii) signal contamination by intrinsic alignments; and (iii) systematic effects due to an incorrect modelling of non-linear scales. First, we show that a comprehensive, multi-wavelength analysis provides a self-calibration method for experimental systematic effects, only implying <50% increment on the errors on cosmological parameters. We also illustrate how the cross-correlation between radio and optical/near-IR surveys alone is able to remove residual systematics with variance as large as 0.00001, i.e. the same order of magnitude of the cosmological signal. This also opens the possibility of using such a cross-correlation as a means to detect unknown experimental systematics. Secondly, we demonstrate that, thanks to polarisation information, radio weak lensing surveys will be able to mitigate contamination by intrinsic alignments, in a way similar but fully complementary to available self-calibration methods based on position-shear correlations. Lastly, we illustrate how radio weak lensing experiments, reaching higher redshifts than those accessible to optical surveys, will probe dark energy and the growth of cosmic structures in regimes less contaminated by non-linearities in the matter perturbations. For instance, the higher-redshift bins of radio catalogues peak at z~0.8-1, whereas their optical/near-IR counterparts are limited to z<0.5-0.7. This translates into having a cosmological signal 2 to 5 times less contaminated by non-linear perturbations.Comment: 16 pages, 10 figures, 2 tables; improved discussion of experimental systematics in Sec. 2; updated to match published versio

SKA Weak Lensing II: Simulated Performance and Survey Design Considerations

We construct a pipeline for simulating weak lensing cosmology surveys with the Square Kilometre Array (SKA), taking as inputs telescope sensitivity curves; correlated source flux, size and redshift distributions; a simple ionospheric model; source redshift and ellipticity measurement errors. We then use this simulation pipeline to optimise a 2-year weak lensing survey performed with the first deployment of the SKA (SKA1). Our assessments are based on the total signal-to-noise of the recovered shear power spectra, a metric that we find to correlate very well with a standard dark energy figure of merit. We first consider the choice of frequency band, trading off increases in number counts at lower frequencies against poorer resolution; our analysis strongly prefers the higher frequency Band 2 (950-1760 MHz) channel of the SKA-MID telescope to the lower frequency Band 1 (350-1050 MHz). Best results would be obtained by allowing the centre of Band 2 to shift towards lower frequency, around 1.1 GHz. We then move on to consider survey size, finding that an area of 5,000 square degrees is optimal for most SKA1 instrumental configurations. Finally, we forecast the performance of a weak lensing survey with the second deployment of the SKA. The increased survey size (3$\pi$\,steradian) and sensitivity improves both the signal-to-noise and the dark energy metrics by two orders of magnitude.Comment: 15 pages, 11 figures, 1 table. Comments welcome. Updated to match published versio