Are Coronal Loops Isothermal or Multithermal? Yes!

Surprisingly few solar coronal loops have been observed simultaneously with TRACE and SOHO/CDS, and even fewer analyses of these loops have been conducted and published. The SOHO Joint Observing Program 146 was designed in part to provide the simultaneous observations required for in-depth temperature analysis of active region loops and determine whether these loops are isothermal or multithermal. The data analyzed in this paper were taken on 2003 January 17 of AR 10250. We used TRACE filter ratios, emission measure loci, and two methods of differential emission measure analysis to examine the temperature structure of three different loops. TRACE and CDS observations agree that Loop 1 is isothermal with Log T $=$ 5.85, both along the line of sight as well as along the length of the loop leg that is visible in the CDS field of view. Loop 2 is hotter than Loop 1. It is multithermal along the line of sight, with significant emission between 6.2 $<$ Log T $<$ 6.4, but the loop apex region is out of the CDS field of view so it is not possible to determine the temperature distribution as a function of loop height. Loop 3 also appears to be multithermal, but a blended loop that is just barely resolved with CDS may be adding cool emission to the Loop 3 intensities and complicating our results. So, are coronal loops isothermal or multithermal? The answer appears to be yes

Accumulation of 5-hydroxynorvaline in maize (Zea mays) leaves is induced by insect feeding and abiotic stress.

Plants produce a wide variety of defensive metabolites to protect themselves against herbivores and pathogens. Non-protein amino acids, which are present in many plant species, can have a defensive function through their mis-incorporation during protein synthesis and/or inhibition of biosynthetic pathways in primary metabolism. 5-Hydroxynorvaline was identified in a targeted search for previously unknown non-protein amino acids in the leaves of maize (Zea mays) inbred line B73. Accumulation of this compound increases during herbivory by aphids (Rhopalosiphum maidis, corn leaf aphid) and caterpillars (Spodoptera exigua, beet armyworm), as well as in response to treatment with the plant signalling molecules methyl jasmonate, salicylic acid and abscisic acid. In contrast, ethylene signalling reduced 5-hydroxynorvaline abundance. Drought stress induced 5-hydroxynorvaline accumulation to a higher level than insect feeding or treatment with defence signalling molecules. In field-grown plants, the 5-hydroxynorvaline concentration was highest in above-ground vegetative tissue, but it was also detectable in roots and dry seeds. When 5-hydroxynorvaline was added to aphid artificial diet at concentrations similar to those found in maize leaves and stems, R. maidis reproduction was reduced, indicating that this maize metabolite may have a defensive function. Among 27 tested maize inbred lines there was a greater than 10-fold range in the accumulation of foliar 5-hydroxynorvaline. Genetic mapping populations derived from a subset of these inbred lines were used to map quantitative trait loci for 5-hydroxynorvaline accumulation to maize chromosomes 5 and 7

All Coronal Loops are the Same: Evidence to the Contrary

The 1998 April 20 spectral line data from the Coronal Diagnostics Spectrometer (CDS) on the {\it Solar and Heliospheric Observatory} (\SOHO) shows a coronal loop on the solar limb. Our original analysis of these data showed that the plasma was multi-thermal, both along the length of the loop and along the line of sight. However, more recent results by other authors indicate that background subtraction might change these conclusions, so we consider the effect of background subtraction on our analysis. We show Emission Measure (EM) Loci plots of three representative pixels: loop apex, upper leg, and lower leg. Comparisons of the original and background-subtracted intensities show that the EM Loci are more tightly clustered after background subtraction, but that the plasma is still not well represented by an isothermal model. Our results taken together with those of other authors indicate that a variety of temperature structures may be present within loops.Comment: Accepted for publication in ApJ Letter

Effects of Soldier-Derived Terpenes on Soldier Caste Differentiation in the Termite (Reticulitermes flavipes)

Primer pheromones play key roles in regulating division of labor, which is one of the most fundamental and defining aspects of insect sociality. Primer pheromones are chemical messengers that transmit hormone-like messages among colony members; in recipients these messages can either induce or suppress phenotypic caste differentiation. Here, we investigated soldier-caste-derived chemicals as possible primer pheromones in the lower termite Reticulitermes flavipes, a species for which no primer pheromones have yet been identified. We determined that soldier head extracts (SHE), when provided to totipotent workers along with the insect morphogenetic juvenile hormone (JH), significantly enhanced soldier caste differentiation. When applied alone, however, SHE had no impacts on caste differentiation, survivorship, or any other aspect of worker biology. These findings support that soldier-derived chemicals serve as primer pheromones which enhance the action of the endogenous morphogenetic hormone JH. Thus, SHE chemicals apparently have no effect when received under natural conditions by non-receptive individuals with presumably low JH titers. Gas chromatography-mass spectrometry analysis identified two terpenes as the most plentiful components of R. flavipes SHE. Through GC-MS and NMR analyses, these terpenes were identified as γ-cadinene and its corresponding aldehyde, g-cadinenal. Validative bioassays with commercially available cadinene confirmed its activity. However, several other previously identified terpenes were also significantly active. These findings reveal a novel primer pheromone-like function for soldier-derived terpenes in termites, and further suggest convergent evolution of terpene functions in enhancing JH-dependent soldier caste differentiation

The Effects of Parathyroid Hormone Applied at Different Regimes on the Trochanteric Region of the Femur in Ovariectomized Rat Model of Osteoporosis

This study aims to investigate the effects of two application frequencies of parathyroid hormone on the trochanteric region of rat femur. Forty-three-month-old female Sprague-Dawley rats were divided into 4 groups (n = 10/group). Three groups were ovariectomized, and 8 weeks later they were administered the following treatments (5 weeks): soy-free diet (OVX), subcutaneously injected PTH (0.040 mg/kg) 5 days a week (PTH 5x/w), subcutaneously injected PTH (0.040 mg/kg) every 2 days (PTH e2d), and a sham group. The values of the biomechanical and histomorphometric parameters showed higher results in 5x/w animals in comparison to the OVX and PTH 2ed groups. The ratio between bone diameter/marrow diameter (B.Dm/Ma.Dm) in subtrochanteric cross sections did not show any significant differences between PTH 5x/w and PTH e2d. The increased bone formation rate was observed under PTH treatment in both groups mainly at the endosteal side. The endosteum seems here to be one of the targets of PTH with an accelerate bone formation and a pronounced filling-in of intracortical cavities with higher intensity for the PTH 5x/w in comparison to PTH e2d rats

Coronal Temperature Diagnostic Capability of the Hinode/X-Ray Telescope Based on Self-Consistent Calibration

The X-Ray Telescope (XRT) onboard the Hinode satellite is an X-ray imager that observes the solar corona with unprecedentedly high angular resolution (consistent with its 1" pixel size). XRT has nine X-ray analysis filters with different temperature responses. One of the most significant scientific features of this telescope is its capability of diagnosing coronal temperatures from less than 1 MK to more than 10 MK, which has never been accomplished before. To make full use of this capability, accurate calibration of the coronal temperature response of XRT is indispensable and is presented in this article. The effect of on-orbit contamination is also taken into account in the calibration. On the basis of our calibration results, we review the coronal-temperature-diagnostic capability of XRT

First Light Measurements with the XMM-Newton Reflection Grating Spectrometers: Evidence for an Inverse First Ionisation Potential Effect and Anomalous Ne A bundance in the Coronae of HR 1099

The RS CVn binary system HR 1099 was extensively observed by the XMM-Newton observatory in February 2000 as its first-light target. A total of 570 ks of exposure time was accumulated with the Reflection Grating Spectrometers (RGS). The integrated X-ray spectrum between 5-35 Angstrom is of unprecedented quality and shows numerous features attributed to transitions of the elements C, N, O, Ne, Mg, Si, S, Fe, and Ni. We perform an in-depth study of the elemental composition of the average corona of this system, and find that the elemental abundances strongly depend on the first ionisation potential (FIP) of the elements. But different from the solar coronal case, we find an inverse FIP effect, i.e., the abundances (relative to oxygen) increase with increasing FIP. Possible scenarios, e.g., selective enrichment due to Ne-rich flare-like events, are discussed.Comment: 5 pages, 4 figures. Accepted by A&A Letters, XMM issu

On Solving the Coronal Heating Problem

This article assesses the current state of understanding of coronal heating, outlines the key elements of a comprehensive strategy for solving the problem, and warns of obstacles that must be overcome along the way.Comment: Accepted by Solar Physics; Published by Solar Physic

Reflection-enhanced gain in traveling-wave parametric amplifiers

The operating principle of traveling-wave parametric amplifiers is typically understood in terms of the standard coupled mode theory, which describes the evolution of forward propagating waves without any reflections, i.e., for perfect impedance matching. However, in practice, superconducting microwave amplifiers are unmatched nonlinear finite-length devices, where the reflecting waves undergo complex parametric processes, not described by the standard coupled mode theory. Here, we present an analytical solution for the TWPA gain, which includes the interaction of reflected waves. These reflections result in corrections to the well-known results of the standard coupled mode theory, which are obtained for both three-wave and four-wave mixing processes. Due to these reflections, the gain is enhanced and unwanted nonlinear phase modulations are suppressed. Predictions of the model are experimentally demonstrated on two types of unmatched TWPA, based on coplanar waveguides with a central wire consisting of (i) a high kinetic inductance superconductor, and (ii) an array of 2000 Josephson junctions