Hinode 7: Conference Summary and Future Suggestions

This conclusion to the meeting attempts to summarise what we have learnt during the conference (mainly from the review talks) about new observations from Hinode and about theories stimulated by them. Suggestions for future study are also offered.Comment: This is the concluding summary for the Hinode 7 Conference, to be published in Pub. Astron. Soc. Japa

A Life of Fun Playing With Solar Magnetic Fields (Special Historical Review)

This invited memoire describes my fortunate life, which has been enriched by meeting many wonderful people. The story starts at home and university, and continues with accounts of St Andrews and trips to the USA, together with musings on the book "Solar MHD". The nature and results of collaborations with key people from abroad and with students is mentioned at length. Finally, other important aspects of my life are mentioned briefly before wrapping up.Comment: Invited Memoire in the Journal Solar Physic

On the nature of reconnection at a solar coronal null point above a separatrix dome

Three-dimensional magnetic null points are ubiquitous in the solar corona, and in any generic mixed-polarity magnetic field. We consider magnetic reconnection at an isolated coronal null point, whose fan field lines form a dome structure. We demonstrate using analytical and computational models several features of spine-fan reconnection at such a null, including the fact that substantial magnetic flux transfer from one region of field line connectivity to another can occur. The flux transfer occurs across the current sheet that forms around the null point during spine-fan reconnection, and there is no separator present. Also, flipping of magnetic field lines takes place in a manner similar to that observed in quasi-separatrix layer or slip-running reconnection.Comment: Accepted for publication in the Astrophysical Journa

The Effect of Hydrostatic Weighting on the Vertical Temperature Structure of the Solar Corona

We investigate the effect of hydrostatic scale heights ${\lambda}(T)$ in coronal loops on the determination of the vertical temperature structure $T(h)$ of the solar corona. Every method that determines an average temperature at a particular line-of-sight from optically thin emission (e.g. in EUV or soft X-ray wavelengths) of a mutli-temperature plasma, is subject to the emission measure-weighted contributions $dEM(T)/dT$ from different temperatures. Because most of the coronal structures (along open or closed field lines) are close to hydrostatic equilibrium, the hydrostatic temperature scale height introduces a height-dependent weighting function that causes a systematic bias in the determination of the temperature structure $T(h)$ as function of altitude $h$. The net effect is that the averaged temperature seems to increase with altitude, $dT(h)/dh > 0$, even if every coronal loop (of a multi-temperature ensemble) is isothermal in itself. We simulate this effect with differential emission measure distributions observed by {\sl SERTS} for an instrument with a broadband temperature filter such as {\sl Yohkoh/SXT} and find that the apparent temperature increase due to hydrostatic weighting is of order \Delta T \approx T_0 \times h/r_{\sun}. We suggest that this effect largely explains the systematic temperature increase in the upper corona reported in recent studies (e.g. by Sturrock et al., Wheatland et al., or Priest et al.), rather than being an intrinsic signature of a coronal heating mechanism.Comment: 7 pages, 3 figures. ApJ Letters, accepted 2000 April 6, in pres

The influence of a mean magnetic field on three-dimensional magnetohydrodynamic turbulence

Building on results from two-dimensional magnetohydrodynamic (MHD) turbulence (Shebalin, Matthaeus & Montgomery 1983), the development of anisotropic states from initially isotropic ones is investigated numerically for fully three-dimensional incompressible MHD turbulence. It is found that when an external d.c. magnetic field (B₀) is imposed on viscous and resistive MHD systems, excitations are preferentially transferred to modes with wavevectors perpendicular to B₀). The anisotropy increases with increasing mechanical and magnetic Reynolds numbers, and also with increasing wavenumber. The tendency of B₀ to inhibit development of turbulence is also examined

Leaf Mining Insects and Their Parasitoids in the Old-Growth Forest of the Huron Mountains

Leaf mining insects in an old-growth forest along the south central shore of Lake Superior in Michigan are documented. We present the results of a 13-year survey of leaf mining species, larval hosts, seasonal occurrence, and parasitoids, as well as report biological observations. Representative larvae, mines, adults, and parasitoids were preserved. Among the larval host associations, 15 are reported as new. Additionally, 42 parasitoid taxa were identified resulting in six first reports from the New World and 32 new host associations. Two undescribed species (Gelechiidae and Figitidae) discovered through this research were described in earlier publications

A Matter of Interpretation: Federal Courts and the Law

Justice Scalia\u27s engaging essay, “Common-Law Courts in a Civil-Law System: The Role of United States Federal Courts in Interpreting the Constitution and Laws,” and the four comments it provokes, should provide lawyers, judges, and other lawmakers with an interesting evening. Instead of presenting a theoretical view of the role of the federal courts in interpretation, Justice Scalia sketches out a case for “textualism.” “Textualism” is one of several currently contending methods of interpreting statutes and the United States Constitution, and is currently popular among federal judges who see their role as restricting government\u27s powers to those expressly stated in the written text

Examining experiences of transition, instability and coping for young offenders in the community: A qualitative analysis.

This article explores experiences of transition, instability and coping using a qualitative approach with young offenders within a specialist forensic child and adolescent mental health service (CAMHS). Participants were four young people (aged 14–17 years) on community orders under the supervision of local youth offending teams (YOTs). Semi-structured interviews were conducted and data analysed using an inductive thematic analysis approach. Three main themes were identified: (i) people and places; (ii) growth; and (iii) managing difficult experiences. Findings suggest that young offenders are exposed to a wide range of challenging contextual factors including unpredictable or inadequate home environments, numerous transitions (between family members/foster placements and schools), limited engagement with educational settings and a lack of social support, supporting the findings of Paton et al. Findings also portrayed a sense of participants’ ‘psychological growth’ with development along a trajectory from a young child ‘acting out’ in response to the environments in which they were living; through a more reflective stage, in which they were able to begin to consider the situations they found themselves in; before reaching a position in which they were able to look beyond their day-to-day circumstances with some hope that their lives could be different in the future. Furthermore, accounts revealed that these young people had a limited range of functional coping strategies and had largely negative experiences of services. Clinical implications and the need for further research developing professionals’ understanding of the influence of early experiences on young offenders’ behaviour are discussed

Scaling law for the heating of solar coronal loops

We report preliminary results from a series of numerical simulations of the reduced magnetohydrodynamic equations, used to describe the dynamics of magnetic loops in active regions of the solar corona. A stationary velocity field is applied at the photospheric boundaries to imitate the driving action of granule motions. A turbulent stationary regime is reached, characterized by a broadband power spectrum $E_k\simeq k^{-3/2}$ and heating rate levels compatible with the heating requirements of active region loops. A dimensional analysis of the equations indicates that their solutions are determined by two dimensionless parameters: the Reynolds number and the ratio between the Alfven time and the photospheric turnover time. From a series of simulations for different values of this ratio, we determine how the heating rate scales with the physical parameters of the problem, which might be useful for an observational test of this model.Comment: 12 pages, 4 figures. Astrophysical Journal Letters (in press

Catastrophe versus instability for the eruption of a toroidal solar magnetic flux rope

The onset of a solar eruption is formulated here as either a magnetic catastrophe or as an instability. Both start with the same equation of force balance governing the underlying equilibria. Using a toroidal flux rope in an external bipolar or quadrupolar field as a model for the current-carrying flux, we demonstrate the occurrence of a fold catastrophe by loss of equilibrium for several representative evolutionary sequences in the stable domain of parameter space. We verify that this catastrophe and the torus instability occur at the same point; they are thus equivalent descriptions for the onset condition of solar eruptions.Comment: V2: update to conform to the published article; new choice for internal inductance of torus; updated Fig. 2; new Figs. 3, 5, and