6 research outputs found
ALMA Observations of the Sun in Cycle 4 and Beyond
This document was created by the Solar Simulations for the Atacama Large
Millimeter Observatory Network (SSALMON) in preparation of the first regular
observations of the Sun with the Atacama Large Millimeter/submillimeter Array
(ALMA), which are anticipated to start in ALMA Cycle 4 in October 2016. The
science cases presented here demonstrate that a large number of scientifically
highly interesting observations could be made already with the still limited
solar observing modes foreseen for Cycle 4 and that ALMA has the potential to
make important contributions to answering long-standing scientific questions in
solar physics. With the proposal deadline for ALMA Cycle 4 in April 2016 and
the Commissioning and Science Verification campaign in December 2015 in sight,
several of the SSALMON Expert Teams composed strategic documents in which they
outlined potential solar observations that could be feasible given the
anticipated technical capabilities in Cycle 4. These documents have been
combined and supplemented with an analysis, resulting in recommendations for
solar observing with ALMA in Cycle 4. In addition, the detailed science cases
also demonstrate the scientific priorities of the solar physics community and
which capabilities are wanted for the next observing cycles. The work on this
White Paper effort was coordinated in close cooperation with the two
international solar ALMA development studies led by T. Bastian (NRAO, USA) and
R. Brajsa, (ESO). This document will be further updated until the beginning of
Cycle 4 in October 2016. In particular, we plan to adjust the technical
capabilities of the solar observing modes once finally decided and to further
demonstrate the feasibility and scientific potential of the included science
cases by means of numerical simulations of the solar atmosphere and
corresponding simulated ALMA observations.Comment: SSALMON White Paper with focus on potential solar science with ALMA
in Cycle 4; 54 pages. Version 1.2, March 29th, 2016 (updated technical
capabilities and observing plans
Review of Coronal Oscillations - An Observer's View
Recent observations show a variety of oscillation modes in the corona. Early
non-imaging observations in radio wavelengths showed a number of fast-period
oscillations in the order of seconds, which have been interpreted as fast
sausage mode oscillations. TRACE observations from 1998 have for the first time
revealed the lateral displacements of fast kink mode oscillations, with periods
of ~3-5 minutes, apparently triggered by nearby flares and destabilizing
filaments. Recently, SUMER discovered with Doppler shift measurements loop
oscillations with longer periods (10-30 minutes) and relatively short damping
times in hot (7 MK) loops, which seem to correspond to longitudinal slow
magnetoacoustic waves. In addition, propagating longitudinal waves have also
been detected with EIT and TRACE in the lowest density scale height of loops
near sunspots. All these new observations seem to confirm the theoretically
predicted oscillation modes and can now be used as a powerful tool for
``coronal seismology'' diagnostic.Comment: 5 Figure
Plasma diagnostics of transition region 'Moss' using SOHO/CDS and TRACE
Recent observations of solar active regions with the Transition Region and Coronal Explorer (TRACE) have revealed finely textured, low-lying EUV emission, called the ``moss,'' appearing as a bright dynamic pattern with dark inclusions. The moss has been interpreted as the upper transition region by Berger and coworkers. In this study we use SOHO Coronal Diagnostic Spectrometer and TRACE observations of Active Region 8227 on 1998 May 30 to determine the physical parameters of the moss material. We establish that the plasma responsible for the moss emission has a temperature range of (0.6-1.5)x10^6 K and is associated with hot loops (T>2x10^6 K). Moss plasma has an electron density of (2-5)x10^9 cm^-3 at a temperature of 1.3x10^6 K, giving a pressure of 0.7-1.7 dynes cm^-2 (a few times higher than in coronal loops observed in the TRACE Fe IX/X lambda171 passband). The volume filling factor of the moss plasma is of order 0.1, and the path along which the emission originates is of order 1000 km long
Multiple Dynamics in Tumor Microenvironment Under Radiotherapy.
The tumor microenvironment (TME) is an evolutionally low-level and embryonically featured tissue comprising heterogenic populations of malignant and stromal cells as well as noncellular components. Under radiotherapy (RT), the major modality for the treatment of malignant diseases [1], TME shows an adaptive response in multiple aspects that affect the efficacy of RT. With the potential clinical benefits, interests in RT combined with immunotherapy (IT) are intensified with a large scale of clinical trials underway for an array of cancer types. A better understanding of the multiple molecular aspects, especially the cross talks of RT-mediated energy reprogramming and immunoregulation in the irradiated TME (ITME), will be necessary for further enhancing the benefit of RT-IT modality. Coming studies should further reveal more mechanistic insights of radiation-induced instant or permanent consequence in tumor and stromal cells. Results from these studies will help to identify critical molecular pathways including cancer stem cell repopulation, metabolic rewiring, and specific communication between radioresistant cancer cells and the infiltrated immune active lymphocytes. In this chapter, we will focus on the following aspects: radiation-repopulated cancer stem cells (CSCs), hypoxia and re-oxygenation, reprogramming metabolism, and radiation-induced immune regulation, in which we summarize the current literature to illustrate an integrated image of the ITME. We hope that the contents in this chapter will be informative for physicians and translational researchers in cancer radiotherapy or immunotherapy