Impact of an L5 magnetograph on nonpotential solar global magnetic field modeling

We present the first theoretical study to consider what improvement could be obtained in global nonpotential modeling of the solar corona if magnetograph data were available from the L5 Lagrange point, in addition to from the direction of Earth. To consider this, we first carry out a "reference Sun" simulation over two solar cycles. An important property of this simulation is that random bipole emergences are allowed across the entire solar surface at any given time (such as can occur on the Sun). Next we construct two "limited data" simulations, where bipoles are only included when they could be seen from (i) an Earth-based magnetograph and (ii) either Earth- or L5 based magnetographs. The improvement in reproducing the reference Sun simulation when an L5 view is available is quantified through considering global quantities in the limited data simulations. These include surface and polar flux, total magnetic energy, volume electric current, open flux and the number of flux ropes. Results show that when an L5 observational viewpoint is included, the accuracy of the global quantities in the limited data simulations can increase by 26-40%. This clearly shows that a magnetograph at the L5 point could significantly increase the accuracy of global nonpotential modeling and with this the accuracy of future space weather forecasts.Publisher PDFPeer reviewe

Spatial dysfunction in post-tsunami Baan Lion: Taking the Moken beyond vulnerability and tradition

This article focuses on the perpetuation of discourses of vulnerability and tradition for Moken people living on the Andaman Coast in Thailand. These discourses limit opportunities to see Moken agency and changes to contemporary livelihoods/lifestyles. This is depicted through the lens of the post-tsunami reconstructed village of Baan Lion on Koh Phra Thong island. We highlight that inappropriate donor reconstruction has led to spatial dysfunction for the local community (largely Moken). The village provides limited opportunity for place-making, connections to employment and trade, and some of the social benefits offered in other nearby local settings. While donors may have ‘built back safer’, we argue that they have not ‘built back better’, as their perception of local needs, livelihoods and lifestyle has not accounted for changes to contemporary Moken life that have occurred prior to and after the 2004 tsunami. The results are a largely depopulated and dysfunctional space whereby NGO and tourism activities are now trying to build a new sense of community and provide some opportunities to retain at least some of the transient population of Baan Lion

PinR mediates the generation of reversible population diversity in Streptococcus zooepidemicus

Opportunistic pathogens must adapt to and survive in a wide range of complex ecosystems. Streptococcus zooepidemicus is an opportunistic pathogen of horses and many other animals, including humans. The assembly of different surface architecture phenotypes from one genotype is likely to be crucial to the successful exploitation of such an opportunistic lifestyle. Construction of a series of mutants revealed that a serine recombinase, PinR, inverts 114 bp of the promoter of SZO_08560, which is bordered by GTAGACTTTA and TAAAGTCTAC inverted repeats. Inversion acts as a switch, controlling the transcription of this sortase-processed protein, which may enhance the attachment of S. zooepidemicus to equine trachea. The genome of a recently sequenced strain of S. zooepidemicus, 2329 (Sz2329), was found to contain a disruptive internal inversion of 7 kb of the FimIV pilus locus, which is bordered by TAGAAA and TTTCTA inverted repeats. This strain lacks pinR and this inversion may have become irreversible following the loss of this recombinase. Active inversion of FimIV was detected in three strains of S. zooepidemicus, 1770 (Sz1770), B260863 (SzB260863) and H050840501 (SzH050840501), all of which encoded pinR. A deletion mutant of Sz1770 that lacked pinR was no longer capable of inverting its internal region of FimIV. The data highlight redundancy in the PinR sequence recognition motif around a short TAGA consensus and suggest that PinR can reversibly influence the wider surface architecture of S. zooepidemicus, providing this organism with a bet-hedging solution to survival in fluctuating environments

Telomere erosion in NF1 tumorigenesis

Neurofibromatosis type 1 (NF1; MIM# 162200) is a familial cancer syndrome that affects 1 in 3,500 individuals worldwide and is inherited in an autosomal dominant fashion. Malignant Peripheral Nerve Sheath Tumors (MPNSTs) represent a significant cause of morbidity and mortality in NF1 and currently there is no treatment or definite prognostic biomarkers for these tumors. Telomere shortening has been documented in numerous tumor types. Short dysfunctional telomeres are capable of fusion and it is considered that the ensuing genomic instability may facilitate clonal evolution and the progression to malignancy. To evaluate the potential role of telomere dysfunction in NF1-associated tumors, we undertook a comparative analysis of telomere length in samples derived from 10 cutaneous and 10 diffused plexiform neurofibromas, and 19 MPNSTs. Telomere length was determined using high-resolution Single Telomere Length Analysis (STELA). The mean Xp/Yp telomere length detected in MPNSTs, at 3.282 kb, was significantly shorter than that observed in both plexiform neurofibromas (5.793 kb; [p = 0.0006]) and cutaneous neurofibromas (6.141 kb; [p = 0.0007]). The telomere length distributions of MPNSTs were within the length-ranges in which telomere fusion is detected and that confer a poor prognosis in other tumor types. These data indicate that telomere length may play a role in driving genomic instability and clonal progression in NF1-associated MPNSTs

The spatial clustering of ultraluminous infrared galaxies over 1.5 < z < 3

We present measurements of the spatial clustering of galaxies with stellar masses 1011 M, infrared luminosities 1012 L, and star formation rates 200 M yr-1 in two redshift intervals: 1.5 &lt; z &lt; 2.0 and 2 &lt; z &lt; 3. Both samples cluster moderately strongly, with spatial correlation lengths of r0 = 6.14 B1 0.84 h-1 Mpc for the 2 &lt; z &lt; 3 sample and r0 = 5.36 B1 1.28 h-1 Mpc for the 1.5 &lt; z &lt; 2.0 sample. These clustering amplitudes are consistent with both populations residing in dark matter halos with masses of 7 C 1012 M, which is comparable to that seen for optical QSOs at the same epochs. We infer that a minimum dark matter halo mass is an important factor for all forms of luminous, obscured activity in galaxies at z &gt; 1, both starbursts and active galactic nuclei. Adopting plausible models for the growth of dark matter halos with redshift, the halos hosting the 2 &lt; z &lt; 3 sample will likely host poor to rich clusters of galaxies at z = 0, whereas the halos hosting the 1.5 &lt; z &lt; 2.0 sample will likely host L* elliptical galaxies or poor clusters at z = 0. We conclude that ultraluminous infrared galaxies (ULIRGs) at z 2.5 likely signpost stellar buildup in galaxies that will reside in clusters at z = 0 and that ULIRGs at z 1.7 signpost stellar buildup in sources that will either become L* elliptical galaxies or reside in poor clusters at z = 0

Inferring polydomy : a review of spatial, functional and genetic methods for identifying colony boundaries

Identifying the boundaries of a social insect colony is vital for properly understanding its ecological function and evolution. Many species of ants are polydomous: colonies inhabit multiple, spatially separated, nests. Ascertaining which nests are parts of the same colony is an important consideration when studying polydomous populations. In this paper, we review the methods that are used to identify which nests are parts of the same polydomous colony and to determine the boundaries of colonies. Specifically, we define and discuss three broad categories of approach: identifying nests sharing resources, identifying nests sharing space, and identifying nests sharing genes. For each of these approaches, we review the theoretical basis, the limitations of the approach and the methods that can be used to implement it. We argue that all three broad approaches have merits and weaknesses, and provide a methodological comparison to help researchers select the tool appropriate for the biological question they are investigating

Detailed modelling of a large sample of Herschel sources in the Lockman Hole: identification of cold dust and of lensing candidates through their anomalous SEDs

We have studied in detail a sample of 967 SPIRE sources with 5σ detections at 350 and 500 μm and associations with Spitzer-SWIRE 24 μm galaxies in the HerMES-Lockman survey area, fitting theirmid- and far-infrared, and submillimetre, spectral energy distributions (SEDs) in an automatic search with a set of six infrared templates. For almost 300 galaxies,we havemodelled their SEDs individually to ensure the physicality of the fits. We confirm the need for the new cool and cold cirrus templates, and also of the young starburst template, introduced in earlier work. We also identify 109 lensing candidates via their anomalous SEDs and provide a set of colour–redshift constraints which allow lensing candidates to be identified from combined Herschel and Spitzer data. The picture that emerges of the submillimetre galaxy population is complex, comprising ultraluminous and hyperluminous starbursts, lower luminosity galaxies dominated by interstellar dust emission, lensed galaxies and galaxies with surprisingly cold (10–13 K) dust. 11 per cent of 500 μm selected sources are lensing candidates. 70 per cent of the unlensed sources are ultraluminous infrared galaxies and 26 per cent are hyperluminous. 34 per cent are dominated by optically thin interstellar dust (‘cirrus’) emission, but most of these are due to cooler dust than is characteristic of our Galaxy. At the highest infrared luminosities we see SEDs dominated by M82, Arp 220 and young starburst types, in roughly equal proportions

Hardware accelerated image processing to enable real-time adaptive radiotherapy

The accuracy of radiotherapy is constrained by organ motion and deformation occurring between the acquisition of CT and MR images used to plan the treatment and the time at which the treatment is delivered. Adaptive radiotherapy uses image data acquired at the time of treatment to adapt the original treatment plan to match the current patient anatomy. Currently, the image processing and dose calculation algorithms required to perform this plan adaptation cannot be executed in a clinically acceptable timeframe. Hardware acceleration has the potential to speedup these algorithms, making real-time adaptive radiotherapy a clinical possibility[1]. Hardware acceleration is a technique where an algorithm is implemented using hardware that is better suited to the specific algorithm than more general purpose processors in order to reduce the execution time of the algorithm. This can be achieved using field programmable gate arrays (FPGA), which are devices consisting of reconfigurable hardware, allowing their function to be customised for a specific application. These devices have been shown to be able to accelerate image processing algorithms pertinent to adaptive radiotherapy[2]. In this study a global thresholding algorithm based on Otsu’s method combined with a three dimensional mean filter was used to segment a series of CT images of a Modus QUASAR respiratory motion phantom into three unique classes. A Xilinx Zynq Z-7020 device consisting of a dual-core ARM Cortex-A9 central processing unit (CPU) coupled to an 85 000 logic cell FPGA was used to accelerate the algorithm by implementing sections of it in the reconfigurable hardware. The execution time of this implementation was compared to an implementation running on an ARM CPU and Intel Core-i5 CPU. The execution times of the implementations are shown in table 1. The hardware accelerated implementation was found to execute nearly sixty times as fast as the un-accelerated algorithm. The hardware accelerated implementation was also found to run around 14% faster than on the more powerful Intel Core-i5 CPU. Figure 1 shows an example of the segmentation results where the blue contour represents the boundary between two of the classes. In the algorithms presented here the overhead of transferring data to the hardware represents a significant proportion of the algorithm execution time. It is anticipated that greater acceleration will be possible for algorithms with greater computational complexity because the data transfer overhead will represent a smaller proportion of the overall execution time. The requirement for fast processing in radiotherapy is likely to increase as the amount of data available to more accurately guide treatment increases through the use of techniques such as 4D CT and image-guided radiotherapy. FPGA have been shown to be effective at accelerating certain algorithms required for real-time adaptive radiotherapy, however, more research is required to establish which will execute faster on other types of hardware, such as CPU and graphical processing units (GPU). It is likely that heterogeneous computing platforms, composed of a mixture of hardware architectures, will be used in the future implementation of real-time adaptive radiotherapy. References: 1.K. Østergaard Noe, B.D. De Senneville, U.V. Elstrøm, K. Tanderup, T.S. Sørensen, “Acceleration and validation of optical flow based deformable registration for image-guided radiotherapy,” Acta Oncologica, vol. 47, no. 7, pp.1286-1293, 2008 2.O. Dandekar, R. Shekhar, “FPGA-Accelerated Deformable Image Registration for Improved Target-Delineation During CT-Guided Interventions,” IEEE Trans. Biomed. Circuits Syst., vol. 1, no. 2, pp.116-127, 200