The coronal fricative problem

PubMed Central

Dinnsen, Daniel A.; Dow, Michael C.; Gierut, Judith A.; Morrisette, Michele L.; Green, Christopher R.

2013-01-01

This paper examines a range of predicted versus attested error patterns involving coronal fricatives (e.g. [s, z, θ, ð]) as targets and repairs in the early sound systems of monolingual English-acquiring children. Typological results are reported from a cross-sectional study of 234 children with phonological delays (ages 3 years; 0 months to 7;9). Our analyses revealed different instantiations of a putative developmental conspiracy within and across children. Supplemental longitudinal evidence is also presented that replicates the cross-sectional results, offering further insight into the life-cycle of the conspiracy. Several of the observed typological anomalies are argued to follow from a modified version of Optimality Theory with Candidate Chains (McCarthy, 2007). PMID:24790247

Formation and evolution of coronal rain observed by SDO/AIA on February 22, 2012

NASA Astrophysics Data System (ADS)

Vashalomidze, Z.; Kukhianidze, V.; Zaqarashvili, T. V.; Oliver, R.; Shergelashvili, B.; Ramishvili, G.; Poedts, S.; De Causmaecker, P.

2015-05-01

Context. The formation and dynamics of coronal rain are currently not fully understood. Coronal rain is the fall of cool and dense blobs formed by thermal instability in the solar corona towards the solar surface with acceleration smaller than gravitational free fall. Aims: We aim to study the observational evidence of the formation of coronal rain and to trace the detailed dynamics of individual blobs. Methods: We used time series of the 171 Å and 304 Å spectral lines obtained by the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamic Observatory (SDO) above active region AR 11420 on February 22, 2012. Results: Observations show that a coronal loop disappeared in the 171 Å channel and appeared in the 304 Å line more than one hour later, which indicates a rapid cooling of the coronal loop from 1 MK to 0.05 MK. An energy estimation shows that the radiation is higher than the heat input, which indicates so-called catastrophic cooling. The cooling was accompanied by the formation of coronal rain in the form of falling cold plasma. We studied two different sequences of falling blobs. The first sequence includes three different blobs. The mean velocities of the blobs were estimated to be 50 km s-1, 60 km s-1 and 40 km s-1. A polynomial fit shows the different values of the acceleration for different blobs, which are lower than free-fall in the solar corona. The first and second blob move along the same path, but with and without acceleration, respectively. We performed simple numerical simulations for two consecutive blobs, which show that the second blob moves in a medium that is modified by the passage of the first blob. Therefore, the second blob has a relatively high speed and no acceleration, as is shown by observations. The second sequence includes two different blobs with mean velocities of 100 km s-1 and 90 km s-1, respectively. Conclusions: The formation of coronal rain blobs is connected with the process of catastrophic cooling. The different acceleration of different coronal rain blobs might be due to the different values in the density ratio of blob to corona. All blobs leave trails, which might be a result of continuous cooling in their tails. Two movies attached to Fig. 1 are available in electronic form at http://www.aanda.org

Numerical modeling of coronal mass ejections based on various pre-event model atmospheres

NASA Technical Reports Server (NTRS)

Suess, S. T.; Wang, A. H.; Wu, S. T.; Poletto, G.

1994-01-01

We examine how the initial state (pre-event corona) affects the numerical MHD simulation for a coronal mass ejection (CME). Earlier simulations based on a pre-event corona with a homogeneous density and temperature distribution at lower boundary (i.e. solar surface) have been used to analyze the role of streamer properties in determining the characteristics of loop-like transients. The present paper extends these studies to show how a broader class of global coronal properties leads not only to different types of CME's, but also modifies the adjacent quiet corona and/or coronal holes. We consider four pre-event coronal cases: (1) Constant boundary conditions and a polytropic gas with gamma = 1.05; (2) Non-constant (latitude dependent) boundary conditions and a polytropic gas with gamma = 1.05; (3) Constant boundary conditions with a volumetric energy source and gamma = 1.67; (4) Non-constant (latitude dependent) boundary conditions with a volumetric energy source and gamma = 1.67. In all models, the pre-event magnetic fields separate the corona into closed field regions (streamers) and open field regions. The CME's initiation is simulated by introducing at the base of the corona, within the streamer region, a standard pressure pulse and velocity change. Boundary values are determined using MHD characteristic theory. The simulations show how different CME's, including loop-like transients, clouds, and bright rays, might occur. There are significant new features in comparison to published results. We conclude that the pre-event corona is a crucial factor in dictating CME's properties.

Numerical Modeling of Coronal Mass Ejections Based on Various Pre-event Model Atmospheres

NASA Technical Reports Server (NTRS)

Wang, A. H.; Wu, S. T.; Suess, S. T.; Poletto, G.

1995-01-01

We examine how the initial state (pre-event corona) affects the numerical MHD simulation for a coronal mass ejection (CME). Earlier simulations based on a pre-event corona with a homogeneous density and temperature distribution, at the lower boundary (i.e., solar surface) have been used to analyze the role of streamer properties in determining the characteristics of loop-like transients. The present paper extends these studies to show how a broader class of global coronal properties leads not only to different types of CME's, but also modifies the adjacent quiet corona and/or coronal holes. We consider four pre-event coronal cases: (1) constant boundary conditions and a polytropic gas with gamma = 1.05; (2) non-constant (latitude dependent) boundary conditions and a polytropic gas with gamma = 1.05; (3) constant boundary conditions with a volumetric energy source and gamma = 1.67; (4) non-constant (latitude dependent) boundary conditions with a volumetric energy source and gamma = 1.67. In all models, the pre-event magnetic fields separate the corona into closed field regions (streamers) and open field regions. The CME's initiation is simulated by introducing at the base of the corona, within the streamer region, a standard pressure pulse and velocity change. Boundary values are determined using magnetohydrodynamic (MHD) characteristic theory. The simulations show how different CME's, including loop-like transients, clouds and bright rays, might occur. There are significant new features in comparison to published results. We conclude that the pre-event corona is a crucial factor in dictating CME's properties.

76 FR 20606 - Proposed Flood Elevation Determinations

Federal Register 2010, 2011, 2012, 2013, 2014

2011-04-13

... source(s) Location of referenced ground [caret] Communities affected elevation ** Elevation in meters (MSL) Effective Modified Sevier County, Utah, and Incorporated Areas Albinus Canyon Approximately 400... Creek Split Flow Approximately 400 feet None +5435 Town of Joseph. downstream of State Highway 118. At...

Coronal plasma development in wire-array z-pinches made of twisted-pairs

NASA Astrophysics Data System (ADS)

Hoyt, C. L.; Greenly, J. B.; Gourdain, P. A.; Knapp, P. F.; Pikuz, S. A.; Shelkovenko, T. A.; Hammer, D. A.; Kusse, B. R.

2009-11-01

We have investigated coronal and core plasma development in wire array z-pinches in which single fine wires are replaced by twisted-pairs (``cable'') on the 1 MA, 100 ns rise time COBRA pulsed power generator. X-ray radiography, employed to investigate dense wire core expansion, showed periodic axial nonuniformity and evidence for shock waves developing where the individual wire plasmas collide. Laser shadowgraphy images indicated that the axial instability properties of the coronal plasma are substantially modified from ordinary wire arrays. Cable mass per unit length, material and the twist wavelength were varied in order to study their effects upon the instability wavelength. Implosion uniformity and bright-spot formation, as well as magnetic topology evolution, have also been investigated using self-emission imaging, x-ray diagnostics and small B-dot probes, respectively. Results from the cable-array z-pinches will be compared with results from ordinary wire-array z-pinches. This research was supported by the SSAA program of the National Nuclear Security Administration under DOE Cooperative agreement DE-FC03-02NA00057.

Measuring Temperature-Dependent Propagating Disturbances in Coronal Fan Loops Using Multiple SDO-AIA Channels and Surfing Transform Technique

NASA Technical Reports Server (NTRS)

Uritskiy, Vadim M.; Davila, Joseph M.; Viall, Nicholeen M.; Ofman, Leon

2013-01-01

A set of co-aligned high resolution images from the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory (SDO) is used to investigate propagating disturbances (PDs) in warm fan loops at the periphery of a non-flaring active region NOAA AR 11082. To measure PD speeds at multiple coronal temperatures, a new data analysis methodology is proposed enabling quantitative description of sub visual coronal motions with low signal-to-noise ratios of the order of 0.1. The technique operates with a set of one-dimensional surfing signals extracted from position-timeplots of several AIA channels through a modified version of Radon transform. The signals are used to evaluate a two-dimensional power spectral density distribution in the frequency - velocity space which exhibits a resonance in the presence of quasi-periodic PDs. By applying this analysis to the same fan loop structures observed in several AIA channels, we found that the traveling velocity of PDs increases with the temperature of the coronal plasma following the square root dependence predicted for the slow mode magneto-acoustic wave which seems to be the dominating wave mode in the studied loop structures. This result extends recent observations by Kiddie et al. (2012) to a more general class of fan loop systems not associated with sunspots and demonstrating consistent slow mode activity in up to four AIA channels.

Internal and External Reconnection Series Homologous Solar Flares

NASA Technical Reports Server (NTRS)

Sterling, Alphonse C.; Moore, Ronald L.

2001-01-01

Using data from the extreme ultraviolet imaging telescope (EIT) on SOHO and the soft X-ray telescope (SXT) on Yohkoh, we examine a series of morphologically homologous solar flares occurring in National Oceanic and Atmospheric Administration (NOAA) active region 8210 over May 1-2, 1998. An emerging flux region (EFR) impacted against a sunspot to the west and next to a coronal hole to the east is the source of the repeated flaring. An SXT sigmoid parallels the EFR's neutral line at the site of the initial flaring in soft X rays. In EIT each flaring episode begins with the formation of a crinkle pattern external to the EFR. These EIT crinkles move out from, and then in toward, the EFR with velocities approx. 20 km/ s. A shrinking and expansion of the width of the coronal hole coincides with the crinkle activity, and generation and evolution of a postflare loop system begins near the time of crinkle formation. Using a schematic based on magnetograms of the region, we suggest that these observations are consistent with the standard reconnection-based model for solar eruptions but are modified by the presence of the additional magnetic fields of the sunspot and coronal hole. In the schematic, internal reconnection begins inside of the EFR-associated fields, unleashing a flare, postflare loops, and a coronal mass ejection (CME). External reconnection, first occurring between the escaping CME and the coronal hole field and second occurring between fields formed as a result of the first external reconnection, results in the EIT crinkles and changes in the coronal hole boundary. By the end of the second external reconnection, the initial setup is reinstated; thus the sequence can repeat, resulting in morphologically homologous eruptions. Our inferred magnetic topology is similar to that suggested in the "breakout model" of eruptions although we cannot determine if our eruptions are released primarily by the breakout mechanism (external reconnection) or, alternatively, primarily by the internal reconnection.

A normal incidence, high resolution X-ray telescope for solar coronal observations

NASA Technical Reports Server (NTRS)

Golub, L.

1984-01-01

A Normal Incidence high resolution X-ray Telescope is reported. The design of a telescope assembly which, after fabrication, will be integrated with the mirror fabrication process is described. The assembly is engineered to fit into the Black Brant rocket skin to survive sounding rocket launch conditions. A flight ready camera is modified and tested.

Modified Mercalli intensity assignments for the May 16, 1909, Northern Plains earthquake

USGS Publications Warehouse

Bakun, W.H.; Stickney, M.C.; Rogers, G.; Ristau, J.

2010-01-01

We use newspaper accounts from the United States and Canada to assign modified Mercalli intensity (MMI) at 90 towns for the May 16, 1909 Northern Plains earthquake. Our MMI assignments generally are consistent with those plotted on Nuttli's (1976) isoseiemal map. The earthquake was felt over more than 1,500,000 km2 in the states of Minnesota, Montana, North Dakota, South Dakota, and Wyoming and the provinces of Alberta, Manitoba, Ontario, and Saskatchewan.

TRANSITION-REGION/CORONAL SIGNATURES AND MAGNETIC SETTING OF SUNSPOT PENUMBRAL JETS: HINODE (SOT/FG), Hi-C, AND SDO/AIA OBSERVATIONS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tiwari, Sanjiv K.; Moore, Ronald L.; Winebarger, Amy R.

2016-01-10

Penumbral microjets (PJs) are transient narrow bright features in the chromosphere of sunspot penumbrae, first characterized by Katsukawa et al. using the Ca ii H-line filter on Hinode's Solar Optical Telescope (SOT). It was proposed that the PJs form as a result of reconnection between two magnetic components of penumbrae (spines and interspines), and that they could contribute to the transition region (TR) and coronal heating above sunspot penumbrae. We propose a modified picture of formation of PJs based on recent results on the internal structure of sunspot penumbral filaments. Using data of a sunspot from Hinode/SOT, High Resolution Coronalmore » Imager, and different passbands of the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory, we examine whether PJs have signatures in the TR and corona. We find hardly any discernible signature of normal PJs in any AIA passbands, except for a few of them showing up in the 1600 Å images. However, we discovered exceptionally stronger jets with similar lifetimes but bigger sizes (up to 600 km wide) occurring repeatedly in a few locations in the penumbra, where evidence of patches of opposite-polarity fields in the tails of some penumbral filaments is seen in Stokes-V images. These tail PJs do display signatures in the TR. Whether they have any coronal-temperature plasma is unclear. We infer that none of the PJs, including the tail PJs, directly heat the corona in active regions significantly, but any penumbral jet might drive some coronal heating indirectly via the generation of Alfvén waves and/or braiding of the coronal field.« less

The Solar Wind Source Cycle: Relationship to Dynamo Behavior

NASA Astrophysics Data System (ADS)

Luhmann, J. G.; Li, Y.; Lee, C. O.; Jian, L. K.; Petrie, G. J. D.; Arge, C. N.

2017-12-01

Solar cycle trends of interest include the evolving properties of the solar wind, the heliospheric medium through which the Sun's plasmas and fields interact with Earth and the planets -including the evolution of CME/ICMEs enroute. Solar wind sources include the coronal holes-the open field regions that constantly evolve with solar magnetic fields as the cycle progresses, and the streamers between them. The recent cycle has been notably important in demonstrating that not all solar cycles are alike when it comes to contributions from these sources, including in the case of ecliptic solar wind. In particular, it has modified our appreciation of the low latitude coronal hole and streamer sources because of their relative prevalence. One way to understand the basic relationship between these source differences and what is happening inside the Sun and on its surface is to use observation-based models like the PFSS model to evaluate the evolution of the coronal field geometry. Although the accuracy of these models is compromised around solar maximum by lack of global surface field information and the sometimes non-potential evolution of the field related to more frequent and widespread emergence of active regions, they still approximate the character of the coronal field state. We use these models to compare the inferred recent cycle coronal holes and streamer belt sources of solar wind with past cycle counterparts. The results illustrate how (still) hemispherically asymmetric weak polar fields maintain a complex mix of low-to-mid latitude solar wind sources throughout the latest cycle, with a related marked asymmetry in the hemispheric distribution of the ecliptic wind sources. This is likely to be repeated until the polar field strength significantly increases relative to the fields at low latitudes, and the latter symmetrize.

75 FR 28511 - Proposed Flood Elevation Determinations

Federal Register 2010, 2011, 2012, 2013, 2014

2010-05-21

... referenced ground [caret] Communities affected elevation Elevation in meters (MSL) Effective Modified... feet above ground. [caret] Mean Sea Level, rounded to the nearest 0.1 meter. ** BFEs to be changed... upstream of the confluence with Williams Creek. Green River At Western Kentucky +400 +401 Town of Rockport...

A Novel Esthetic Approach using Connective Tissue Graft for Soft Tissue Defect Following Surgical Excision of Gingival Fibrolipoma

PubMed Central

Parthasarathy, Harinath; Kumar, Praveenkrishna; Gajendran, Priyalochana; Appukuttan, Devapriya

2014-01-01

The aim of the present case report is to evaluate the adjunctive use of a connective tissue graft to overcome soft tissue defects following excision of a gingival fibrolipoma in the aesthetic region. Connective tissue graft has been well documented for treating defects of esthetic concern. However, the literature does not contain many reports on the esthetic clinical outcome following the use of connective tissue graft secondary to excision of soft tissue tumours. A 28-year-old male patient reported with a complaint of a recurrent growth in relation to his lower front tooth region. The lesion which was provisionally diagnosed as fibroma was treated with a complete surgical excision, following which a modified coronally advanced flap and connective tissue graft was adopted to overcome the soft tissue defect. The excised growth was diagnosed histologically as fibrolipoma. One year follow up showed no recurrence of the lesion and good esthetics.The adjunctive use of the connective tissue graft and modified coronally advanced flap predictably yields optimal soft tissue fill and excellent esthetics. Hence, routine use of this procedure may be recommended for surgical excision of soft tissue growths in esthetically sensitive areas. PMID:25584336

18 CFR 153.7 - Contents of application.

Code of Federal Regulations, 2014 CFR

2014-04-01

..., DEPARTMENT OF ENERGY REGULATIONS UNDER NATURAL GAS ACT APPLICATIONS FOR AUTHORIZATION TO CONSTRUCT, OPERATE, OR MODIFY FACILITIES USED FOR THE EXPORT OR IMPORT OF NATURAL GAS Application Under Section 3 § 153.7... under the laws of which the applicant was organized, and the town or city where applicant's principal...

18 CFR 153.7 - Contents of application.

Code of Federal Regulations, 2011 CFR

2011-04-01

..., DEPARTMENT OF ENERGY REGULATIONS UNDER NATURAL GAS ACT APPLICATIONS FOR AUTHORIZATION TO CONSTRUCT, OPERATE, OR MODIFY FACILITIES USED FOR THE EXPORT OR IMPORT OF NATURAL GAS Application Under Section 3 § 153.7... under the laws of which the applicant was organized, and the town or city where applicant's principal...

18 CFR 153.7 - Contents of application.

Code of Federal Regulations, 2013 CFR

2013-04-01

..., DEPARTMENT OF ENERGY REGULATIONS UNDER NATURAL GAS ACT APPLICATIONS FOR AUTHORIZATION TO CONSTRUCT, OPERATE, OR MODIFY FACILITIES USED FOR THE EXPORT OR IMPORT OF NATURAL GAS Application Under Section 3 § 153.7... under the laws of which the applicant was organized, and the town or city where applicant's principal...

18 CFR 153.7 - Contents of application.

Code of Federal Regulations, 2012 CFR

2012-04-01

..., DEPARTMENT OF ENERGY REGULATIONS UNDER NATURAL GAS ACT APPLICATIONS FOR AUTHORIZATION TO CONSTRUCT, OPERATE, OR MODIFY FACILITIES USED FOR THE EXPORT OR IMPORT OF NATURAL GAS Application Under Section 3 § 153.7... under the laws of which the applicant was organized, and the town or city where applicant's principal...

78 FR 14697 - Final Flood Elevation Determinations

Federal Register 2010, 2011, 2012, 2013, 2014

2013-03-07

... Communities affected elevation above ground [caret] Elevation in meters (MSL) Modified Cecil County, Maryland... 1 to Stone Run At the Stone Run +271 Town of Rising Sun, confluence. Unincorporated Areas of Cecil County. Approximately 460 feet +359 downstream of Pierce Road. Tributary 2 to Stone Run At the Stone Run...

Longitudinal changes in the intake of vitamins and minerals of elderly Europeans. SENECA Investigators.

PubMed

Amorim Cruz, J A; Moreiras, O; Brzozowska, A

1996-07-01

To assess longitudinal changes in intake of vitamins and minerals in elderly Europeans. Longitudinal study including the collection of dietary intake data in 1988/1989 and in 1993. Baseline and follow-up data were collected from nine European towns: Belgium: Hamme (H/B); Denmark: Roskilde (R/DK); France: Haguenau (H/F) and Romans (R/F); Italy: Padua (P/I); the Netherlands: Culemborg (C/NL); Portugal: Vila Franca de Xira (V/P); Spain: Betanzos (B/E) and Switzerland: Yverdon (Y/CH). In four other towns dietary intake data were collected in 1993 only: Portugal: Coimbra (C/P); Poland: Marki (M/PL); Northern Ireland: Ballymoney-Limavady-Portstewart (BLP/NI/UK) and United States: Mansfield (Connecticut) (M/CT/USA). Using standardized methods, data were collected from a random sample of 658 elderly men and 731 women born between 1913 and 1918. Dietary intake data were collected by a validated modified dietary history method. A significant decrease in the median intake of vitamin B1, vitamin B2, vitamin B6, vitamin C or iron was observed in several towns and for most of these nutrients in H/B, R/DK, R/F and V/P. Over the 4-y follow-up period, the proportion of elderly people with nutrient intakes below the lowest European RDI's increased for various nutrients in most towns, whereas the nutrient density of the diet, especially for iron and vitamin C, decreased significantly only in a few towns. The proportion of elderly people taking nutrient supplements varied from less than 5% in H/B to 60% in R/DK. The observed decrease in intake of some vitamins and minerals in most of the participating towns, indicates an increased risk for malnutrition in elderly Europeans.

NUTRITIONAL STATUS AND ASSOCIATED FACTORS AMONG CHILDREN LESS THAN FIVE YEARS OF AGE IN TEHSIL ZARGHOON TOWN, DISTRICT QUETTA, BALUCHISTAN.

PubMed

Achakzai, Pairzo; Khan, Rukhsana

2016-01-01

Globally, more than one-third of mortalities in children under five years of age are attributable to malnutrition. The prevalence of malnourished children in Pakistan is inclining. A knowledge gap exists due to availability of limited literature about the nutritional status of children in rural Baluchistan. Therefore, this study assessed the magnitude and factors associated with nutritional status of children of less than five years of age in Tehsil Zarghoon Town of District Quetta. A community based cross-sectional study was conducted in two rural union councils of Tehsil Zarghoon Town of District Quetta, selected randomly. An existing questionnaire was modified and three research assistants were hired to collect data from 104 children, selected systematically. Data analysis was done using SPSS-20 and World Health Organization (WHO) Anthro software. Results showed that the proportion of stunting and wasting in children comprising the study population was 48.1% and 9.7% respectively. A significant association was demonstrated between stunting and wasting and socio-demographic characteristics, child health characteristics and maternal health characteristics. It was concluded that the nutritional status of children under five years of age in Tehsil Zarghoon Town of district Quetta was unsatisfactory. Thus, community mobilization and incorporation of nutrition related activities in primary health care are recommended.

The Mediolateral Excursion of the Meniscal Bearing during Flexion and Extension of the Knee after Medial Mobile-Bearing Unicompartmental Knee Arthroplasty.

PubMed

Lee, Seung-Yup; Bae, Ji-Hoon; Suh, Dong-Won; Kim, Han-Ju; Lim, Hong-Chul

2017-02-01

This mediolateral excursion of the bearing during knee motion is supposed to be caused by external rotation of the tibia during knee extension. However, to our knowledge, there is no published clinical evidence supporting these hypotheses. The current study aimed to evaluate the mediolateral excursion of the bearing during flexion-extension motion of the knee after medial unicompartmental knee arthroplasty (UKA). In 52 knees, varus/valgus (F-VarVal) or rotational position (F-Rot) of the femoral component and relative location of the bearing were measured with the standing anteroposterior and modified axial view, respectively. We adopted the modified axial radiographs that are simple to assess the bearing position in the flexed knee. The modified axial view showed excellent inter- and intraobserver agreements. F-Rot in the modified axial view and CT showed a high agreement in terms of validity (r = 0.98; p  < 0.0001). On average, the bearing showed more medial position in extension than flexion of the knee. No correlation was found between the femoral component positions (F-VarVal and F-Rot) and mediolateral bearing excursion ( p  = 0.68 and 0.80, respectively). In conclusion, coronal location of bearing according to flexion-extension of the knee is not influenced by the coronal and axial alignment of the femoral component. With simple radiographic method, more medial position of the bearing according to flexion-extension of the knee. Our method could be used to assess axial rotation of the femoral component and spin-out phenomenon of the bearing following the medial UKA. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

Minimizing Alteration of Posterior Tibial Slope During Opening Wedge High Tibial Osteotomy: a Protocol with Experimental Validation in Paired Cadaveric Knees

PubMed Central

Westermann, Robert W; DeBerardino, Thomas; Amendola, Annunziato

2014-01-01

Introduction The High Tibial Osteotomy (HTO) is a reliable procedure in addressing uni- compartmental arthritis with associated coronal deformities. With osteotomy of the proximal tibia, there is a risk of altering the tibial slope in the sagittal plane. Surgical techniques continue to evolve with trends towards procedure reproducibility and simplification. We evaluated a modification of the Arthrex iBalance technique in 18 paired cadaveric knees with the goals of maintaining sagittal slope, increasing procedure efficiency, and decreasing use of intraoperative fluoroscopy. Methods Nine paired cadaveric knees (18 legs) underwent iBalance medial opening wedge high tibial osteotomies. In each pair, the right knee underwent an HTO using the modified technique, while all left knees underwent the traditional technique. Independent observers evaluated postoperative factors including tibial slope, placement of hinge pin, and implant placement. Specimens were then dissected to evaluate for any gross muscle, nerve or vessel injury. Results Changes to posterior tibial slope were similar using each technique. The change in slope in traditional iBalance technique was -0.3° ±2.3° and change in tibial slope using the modified iBalance technique was -0.4° ±2.3° (p=0.29). Furthermore, we detected no differences in posterior tibial slope between preoperative and postoperative specimens (p=0.74 traditional, p=0.75 modified). No differences in implant placement were detected between traditional and modified techniques. (p=0.85). No intraoperative iatrogenic complications (i.e. lateral cortex fracture, blood vessel or nerve injury) were observed in either group after gross dissection. Discussion & Conclusions Alterations in posterior tibial slope are associated with HTOs. Both traditional and modified iBalance techniques appear reliable in coronal plane corrections without changing posterior tibial slope. The present modification of the Arthrex iBalance technique may increase the efficiency of the operation and decrease radiation exposure to patients without compromising implant placement or global knee alignment. PMID:25328454

Internal and External reconnection in a Series of Homologous Solar Flares

NASA Technical Reports Server (NTRS)

Sterling, Alphonse C.; Moore, Ronald L.; Rose, M. Franklin (Technical Monitor)

2000-01-01

Using data from the Extreme Ultraviolet Telescope (EIT) on SOHO and the Soft X-ray Telescope (SXT) on Yohkoh, we examine a series of morphologically homologous solar flares occurring in NOAA AR 8210 over May 1-2, 1998. An emerging flux region (EFR) impacted against a sunspot to the west and next to a coronal hole to the east is the source of the repeated flaring. An SXT sigmoid parallels the EFR's neutral line at the site of the initial flaring in soft X-rays. In EIT, each flaring episode begins with the formation of a crinkle pattern external to the EFR. These EIT crinkles move out from, and then in toward, the EFR with velocities approximately 20 km/s. A shrinking and expansion of the width of the coronal hole coincides with the crinkle activity, and generation and evolution of a postflare loop system begins near the. time of crinkle formation. Using a schematic based on magnetograms of the region, we suggest that these observations are consistent with the standard reconnection-based model for solar eruptions, but modified by the presence of the additional magnetic fields of the sunspot and coronal hole. In the schematic, internal reconnection begins inside of the EFR-associated fields, unleashing a flare, postflare loops, and a CME. External reconnection, first occurring between the escaping CME and the coronal hole field, and second occurring between fields formed as a result of the first external reconnection, results in the EIT crinkles and changes in the coronal hole boundary. By the end of the second external reconnection, the initial setup is reinstated; thus the sequence can repeat, resulting in morphologically homologous eruptions. Our inferred magnetic topology is similar to that suggested in the "breakout model" of eruptions [Antiochos, 1998], although we cannot determine if our eruptions are released primarily by the breakout mechanism (external reconnection) or, alternatively, are released primarily by the internal reconnection.

University Students' Sense of Belonging to the Home Town: The Role of Residential Mobility

ERIC Educational Resources Information Center

Cicognani, Elvira; Menezes, Isabel; Nata, Gil

2011-01-01

In the study of young people's relationships with residential contexts, it is important to consider the role of developmental tasks (e.g. identity construction, academic and professional choices, etc.) in influencing Place Identity and Sense of Community. Residential mobility may represent an adaptive strategy for modifying some aspects of one's…

[Reconstruction of urban land space based on minimum cumulative resistance model: a case study of Xintang Town, Guangzhou City].

PubMed

Zhong, Shi-Yu; Wu, Qing; Li, Yu; Cheng, Jin-Ping

2012-11-01

Based on the source-sink landscape theory and the principles of ecosystem services, the minimum cumulative resistance (MCR) model was modified, where the urban center construction land was taken as the expansion source, and the contribution rate of ecological land ecosystem services value was considered as the resistance coefficient. With the modified MCR, the urban spatial expansion process of Xintang Town, Guangzhou City was successfully simulated, and, based on the protection of ecological security pattern, the optimum path for reconstructing urban land space was put forward. The simulated urban spatial expansion short path in 1988-2008 was in accordance with the real situation. By the modified MCR, the urban space was divided into four zones of high, higher, medium, and low resistance, with the area of 80.84, 78.90, 24.26, and 61.88 km2, respectively. The expansion path of the urban space was along the route from low to medium and then to high resistance zones successively. The land suitable for eco-protection and construction had an area of 159.74 km2 and 86.14 km2, while the ecological conflict area (17.37 km2) was mainly located in higher and high resistance zones, being 10.38 and 6.99 km2, respectively. The modified MCR could not only effectively reflect the distribution area of urban land use and the conflict relationship between urban construction and ecological protection, but also reasonably judge the best developmental short path for urban spatial expansion.

PLASMA JETS AND ERUPTIONS IN SOLAR CORONAL HOLES: A THREE-DIMENSIONAL FLUX EMERGENCE EXPERIMENT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moreno-Insertis, F.; Galsgaard, K.

2013-07-01

A three-dimensional (3D) numerical experiment of the launching of a hot and fast coronal jet followed by several violent eruptions is analyzed in detail. These events are initiated through the emergence of a magnetic flux rope from the solar interior into a coronal hole. We explore the evolution of the emerging magnetically dominated plasma dome surmounted by a current sheet and the ensuing pattern of reconnection. A hot and fast coronal jet with inverted-Y shape is produced that shows properties comparable to those frequently observed with EUV and X-ray detectors. We analyze its 3D shape, its inhomogeneous internal structure, andmore » its rise and decay phases, lasting for some 15-20 minutes each. Particular attention is devoted to the field line connectivities and the reconnection pattern. We also study the cool and high-density volume that appears to encircle the emerged dome. The decay of the jet is followed by a violent phase with a total of five eruptions. The first of them seems to follow the general pattern of tether-cutting reconnection in a sheared arcade, although modified by the field topology created by the preceding reconnection evolution. The two following eruptions take place near and above the strong-field concentrations at the surface. They show a twisted, {Omega}-loop-like rope expanding in height, with twist being turned into writhe, thus hinting at a kink instability (perhaps combined with a torus instability) as the cause of the eruption. The succession of a main jet ejection and a number of violent eruptions that resemble mini-CMEs and their physical properties suggest that this experiment may provide a model for the blowout jets recently proposed in the literature.« less

Polarity Comparison Between the Coronal PFSS Model Field and the Heliospheric Magnetic Field at 1 AU Over Solar Cycles 21-24

NASA Astrophysics Data System (ADS)

Koskela, J. S.; Virtanen, I. I.; Mursula, K.

2015-12-01

The solar coronal magnetic field forms an important link between the underlying source in the solar photosphere and the heliospheric magnetic field (HMF). The coronal field has traditionally been calculated from the photospheric observations using various magnetic field models between the photosphere and the corona, in particular the potential field source surface (PFSS) model. Despite its simplicity, the predictions of the PFSS model generally agree quite well with the heliospheric observations and match very well with the predictions of more elaborate models. We make here a detailed comparison between the predictions of the PFSS model with the HMF field observed at 1 AU. We use the photospheric field measured at the Wilcox Solar Observatory, SDO/HMI, SOHO/MDI and SOLIS, and the heliospheric magnetic field measurements at 1 AU collected within the OMNI 2 dataset. This database covers the solar cycles 21-24. We use different source surface distances and different numbers of harmonic components for the PFSS model. We find an optimum polarity match between the coronal field and the HMF for source surface distance of 3.5 Rs. Increasing the number of harmonic components beyond the quadrupole does not essentially improve polarity agreement, indicating that the large scale structure of the HMF at 1 AU is responsible for the agreement while the small scale structure is greatly modified between corona and 1 AU. We also discuss the solar cycle evolution of polarity match and find that the PFSS model prediction is most reliable during the declining phase of the solar cycle. We also find large differences in match percentage between northern and southern hemispheres during the times of systematic southward shift of the heliospheric current sheet (the Bashful ballerina).

"Coming to town": the impact of urbanicity, cigarette advertising, and network norms on the smoking attitudes of black women in Cape Town, South Africa.

PubMed

Williams, Chyvette T; Grier, Sonya A; Marks, Amy Seidel

2008-07-01

This study was conducted to examine the effect of urban living on smoking attitudes among black African women in South Africa. We examine how urbanicity affects attitudes toward smoking and how it moderates the relationship between both advertising exposure and network norms on black women's smoking attitudes. Respondents were 975 black women currently living in Cape Town townships, some of which were raised in rural villages or small towns. Respondents completed a cross-sectional survey, which included data on smoking attitudes, norms, and exposure to cigarette advertising. Multiple linear regression analysis was performed with smoking attitudes as the response variable, and urbanicity, cigarette advertising exposure, and network smoking norms as primary explanatory variables. Interactions were tested to determine whether urbanicity modified the effect of advertising exposure and network norms on smoking attitudes. Independent effects of urbanicity, exposure to cigarette advertising, and greater smoking prevalence within women's networks were associated with more favorable smoking attitudes. In addition, urbanicity moderated the relationship between network smoking norms and smoking attitudes, but not cigarette advertising exposure and smoking attitudes. Urbanicity, cigarette advertising, and networks play important roles in women's attitudes toward smoking, and potentially, smoking behavior. Overall, our results suggest that strong and creative anti-smoking efforts are needed to combat the potential for a smoking epidemic among an increasingly urbanized population of black women in South Africa and similar emerging markets. Additional research is warranted.

Magnetic coronae and circumstellar disks - new insights from the Coordinated Synoptic Investigation of NGC2264 (CSI-NGC2264)

NASA Astrophysics Data System (ADS)

Flaccomio, E.

2014-07-01

Proto-planetary disks are affected by radiative and magnetic interactions with the central object. X-ray/UV coronal and accretion-shock emission may drive gas ionization and heating and, consequently, photo-evaporation and disk dispersal. The magnetosphere connecting the star and inner disk mediates mass and angular momentum exchanges and modifies the disk structure. These interconnected processes are highly dynamic and involve material emitting in different bands: the inner disk dust (mIR), the stellar photosphere (optical), accretion shocks (UV/X-rays), and coronae (X-rays). I will present selected results form the Coordinated Synoptic Investigation of NGC2264 (CSI-NGC2264), an unprecedented multi-wavelength month-long observing campaign of the NGC2264 region. Three space telescopes (Spitzer, CoRoT, and Chandra) simultaneously monitored a rich sample of ~3Myr old stars in the mIR, optical, and X-ray bands, providing new insights on the dynamics of the respective emitting regions and their interactions. First, I will discuss magnetic flares: for the first time we observe the heating phase (in the optical), the decay (in X-rays), and, possibly, the disk response to the flare (in the mIR). I will then focus on the longer time-scale relation between X-ray (coronal) and optical (photospheric)/mIR(disk) emission, with particular reference to the obscuration of coronal plasma by temporally varying disk structures.

The Influence of Post System Design and Material on the Biomechanical Behavior of Teeth with Little Remaining Coronal Structure.

PubMed

Pinto, Cristiano Lazzari; Bhering, Claudia Lopes Brilhante; de Oliveira, Gabriel Rodrigues; Maroli, Angélica; Reginato, Vagner Flávio; Caldas, Ricardo Armini; Bacchi, Atais

2018-05-14

To evaluate the influence of different post systems on the biomechanical behavior of teeth with a severe loss of remaining coronal structure. Fifty standardized bovine teeth (n = 10 per group) were restored with: cast post-and-core (CPC), prefabricated metallic post (PFM), parallel glass-fiber post (P-FP), conical glass-fiber post (C-FP), or composite core (no post, CC). The survival rate during thermomechanical challenging (TC), the fracture strength (FS), and failure patterns (FP) were evaluated. Finite element models evaluated the stress distribution after the application of 100 N. All specimens survived TC. Similar FS was observed among post-containing groups. Groups P-FP and CC presented 100% repairable fractures. The von Mises analysis showed the maximum stresses into the root canal in groups restored with metallic posts. Glass-fiber posts and CC presented the maximum stresses at the load contact point. Glass-fiber groups showed lower stresses in the analysis of maximal contact pressure; CPC led to the highest values of contact pressure. The modified von Mises (mvM) stress in dentin did not show differences among groups. Moreover, mvM values did not reach the dentin fracture limit for any group. The type of intracanal post had a relevant influence on the biomechanical behavior of teeth with little remaining coronal structure. © 2018 by the American College of Prosthodontists.

Could CCI or FBCI Fully Eliminate the Impact of Curve Flexibility When Evaluating the Surgery Outcome for Thoracic Curve Idiopathic Scoliosis Patient? A Retrospective Study

PubMed Central

Ni, Haijian; Zhu, Xiaodong; Li, Ming

2015-01-01

Purpose To clarify if CCI or FBCI could fully eliminate the influence of curve flexibility on the coronal correction rate. Methods We reviewed medical record of all thoracic curve AIS cases undergoing posterior spinal fusion with all pedicle screw systems from June 2011 to July 2013. Radiographical data was collected and calculated. Student t test, Pearson correlation analysis and linear regression analysis were used to analyze the data. Results 60 were included in this study. The mean age was 14.7y (10-18y) with 10 males (17%) and 50 females (83%). The average Risser sign was 2.7. The mean thoracic Cobb angle before operation was 51.9°. The mean bending Cobb angle was 27.6° and the mean fulcrum bending Cobb angle was 17.4°. The mean Cobb angle at 2 week after surgery was 16.3°. The Pearson correlation coefficient r between CCI and BFR was -0.856(P<0.001), and between FBCI and FFR was -0.728 (P<0.001). A modified FBCI (M-FBCI) = (CR-0.513)/BFR or a modified CCI (M-CCI) = (CR-0.279)/FFR was generated by curve estimation has no significant correlation with FFR (r=-0.08, p=0.950) or with BFR (r=0.123, p=0.349). Conclusions Fulcrum-bending radiographs may better predict the outcome of AIS coronal correction than bending radiographs in thoracic curveAIS patients. Neither CCI nor FBCI can fully eliminate the impact of curve flexibility on the outcome of correction. A modified CCI or FBCI can better evaluating the corrective effects of different surgical techniques or instruments. PMID:25984945

Could CCI or FBCI Fully Eliminate the Impact of Curve Flexibility When Evaluating the Surgery Outcome for Thoracic Curve Idiopathic Scoliosis Patient? A Retrospective Study.

PubMed

Yang, Changwei; Sun, Xiaofei; Li, Chao; Ni, Haijian; Zhu, Xiaodong; Yang, Shichang; Li, Ming

2015-01-01

To clarify if CCI or FBCI could fully eliminate the influence of curve flexibility on the coronal correction rate. We reviewed medical record of all thoracic curve AIS cases undergoing posterior spinal fusion with all pedicle screw systems from June 2011 to July 2013. Radiographical data was collected and calculated. Student t test, Pearson correlation analysis and linear regression analysis were used to analyze the data. 60 were included in this study. The mean age was 14.7 y (10-18 y) with 10 males (17%) and 50 females (83%). The average Risser sign was 2.7. The mean thoracic Cobb angle before operation was 51.9°. The mean bending Cobb angle was 27.6° and the mean fulcrum bending Cobb angle was 17.4°. The mean Cobb angle at 2 week after surgery was 16.3°. The Pearson correlation coefficient r between CCI and BFR was -0.856(P<0.001), and between FBCI and FFR was -0.728 (P<0.001). A modified FBCI (M-FBCI) = (CR-0.513)/BFR or a modified CCI (M-CCI) = (CR-0.279)/FFR was generated by curve estimation has no significant correlation with FFR (r=-0.08, p=0.950) or with BFR (r=0.123, p=0.349). Fulcrum-bending radiographs may better predict the outcome of AIS coronal correction than bending radiographs in thoracic curveAIS patients. Neither CCI nor FBCI can fully eliminate the impact of curve flexibility on the outcome of correction. A modified CCI or FBCI can better evaluating the corrective effects of different surgical techniques or instruments.

Accuracy and consistency of electronic root canal length determination with electrically isolating rubber stoppers.

PubMed

Kowollik, Susanne; Sonntag, David

2018-03-23

The aim of this study was to investigate the influence of an isolating silicone stopper on the measuring accuracy and display consistency of three electrometric apex locators. The length of the canal to the major foramen was determined electrometrically using an ISO size 10 file in 20 extracted teeth each with natural crowns (Group I), amalgam fillings (Group II) or base-metal crowns (Group III), The measurements were performed with isolating or conventional silicone stoppers using three different apex locators with a four-level scale consistency rating. The use of isolating stoppers resulted in a more consistent display than with conventional stoppers, independent of the presence or type of coronal restoration (P = 0.017). Across all coronal restorations, the position of the major foramen could be determined to within ± 0.5 mm without significant differences (P = 0.79) using conventional and isolating stoppers. The use of modified isolating stoppers provides a significant increase in display consistency. © 2018 Australian Society of Endodontology Inc.

EFFECTS OF ALFVEN WAVES ON ELECTRON CYCLOTRON MASER EMISSION IN CORONAL LOOPS AND SOLAR TYPE I RADIO STORMS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhao, G. Q.; Chen, L.; Wu, D. J.

Solar type I radio storms are long-lived radio emissions from the solar atmosphere. It is believed that these type I storms are produced by energetic electrons trapped within a closed magnetic structure and are characterized by a high ordinary (O) mode polarization. However, the microphysical nature of these emissions is still an open problem. Recently, Wu et al. found that Alfven waves (AWs) can significantly influence the basic physics of wave-particle interactions by modifying the resonant condition. Taking the effects of AWs into account, this work investigates electron cyclotron maser emission driven by power-law energetic electrons with a low-energy cutoffmore » distribution, which are trapped in coronal loops by closed solar magnetic fields. The results show that the emission is dominated by the O mode. It is proposed that this O mode emission may possibly be responsible for solar type I radio storms.« less

Immediate provisionalization of immediate implants in the esthetic zone: a prospective case series evaluating implant survival, esthetics, and bone maintenance.

PubMed

Levin, Barry P; Wilk, Brian L

2013-05-01

This prospective study evaluates immediately placed and immediately provisionalized implants in the esthetic zone. All implants were TiO2-blasted, fluoride-modified, grade 4 titanium, with a coronal microthread design. Bone grafting and guided bone regeneration (GBR) was performed at all sites, and screw-retained temporary restorations were delivered on the day of surgery. All of the provisional crown(s) were out of occlusal function and remained in place for at least 8 weeks prior to initiation of definitive restorative therapy. Bone maintenance (BM) was considered successful if radiographs demonstrated proximal bone levels even or coronal to the implant platform. Of the 29 implants placed, 25 (86 percent) achieved bone maintenance at least 12 months post-loading with the final restorations. This study was considered successful, with 100 percent implant survival after at least 1 year loading of the final restoration, and 100 percent of patients were satisfied with the esthetics of their implant treatment.

Carbon and oxygen X-ray line emission from the interstellar medium

NASA Technical Reports Server (NTRS)

Schnopper, H. W.; Delvaille, J. P.; Rocchia, R.; Blondel, C.; Cheron, C.; Christy, J. C.; Ducros, R.; Koch, L.; Rothenflug, R.

1982-01-01

A soft X-ray, 0.3-1.0 keV spectrum from a 1 sr region which includes a portion of the North Polar Spur, obtained by three rocketborne lithium-drifted silicon detectors, shows the C V, C VI, O VII and O VIII emission lines. The spectrum is well fitted by a two-component, modified Kato (1976) model, where the coronal emission is in collisional equilibrium, with interstellar medium and North Polar Spur temperatures of 1.1 and 3.8 million K, respectively.

Higher-speed coronal mass ejections and their geoeffectiveness

NASA Astrophysics Data System (ADS)

Singh, A. K.; Bhargawa, Asheesh; Tonk, Apeksha

2018-06-01

We have attempted to examine the ability of coronal mass ejections to cause geoeffectiveness. To that end, we have investigated total 571 cases of higher-speed (> 1000 km/s) coronal mass ejection events observed during the years 1996-2012. On the basis of angular width (W) of observance, events of coronal mass ejection were further classified as front-side or halo coronal mass ejections (W = 360°); back-side halo coronal mass ejections (W = 360°); partial halo (120°< W < 360°) and non-halo (W < 120°). From further analysis, we found that front halo coronal mass ejections were much faster and more geoeffective in comparison of partial halo and non-halo coronal mass ejections. We also inferred that the front-sided halo coronal mass ejections were 67.1% geoeffective while geoeffectiveness of partial halo coronal mass ejections and non-halo coronal mass ejections were found to be 44.2% and 56.6% respectively. During the same period of observation, 43% of back-sided CMEs showed geoeffectiveness. We have also investigated some events of coronal mass ejections having speed > 2500 km/s as a case study. We have concluded that mere speed of coronal mass ejection and their association with solar flares or solar activity were not mere criterion for producing geoeffectiveness but angular width of coronal mass ejections and their originating position also played a key role.

Coronal and Prominence Plasmas

NASA Technical Reports Server (NTRS)

Poland, Arthur I. (Editor)

1986-01-01

Various aspects of solar prominences and the solar corona are discussed. The formation of prominences, prominence diagnostics and structure, prominence dissappearance, large scale coronal structure, coronal diagnostics, small scale coronal structure, and non-equilibrium/coronal heating are among the topics covered.

Photospheric magnetic field of an eroded-by-solar-wind coronal mass ejection

NASA Astrophysics Data System (ADS)

Palacios, J.; Cid, C.; Saiz, E.; Guerrero, A.

2017-10-01

We have investigated the case of a coronal mass ejection that was eroded by the fast wind of a coronal hole in the interplanetary medium. When a solar ejection takes place close to a coronal hole, the flux rope magnetic topology of the coronal mass ejection (CME) may become misshapen at 1 AU as a result of the interaction. Detailed analysis of this event reveals erosion of the interplanetary coronal mass ejection (ICME) magnetic field. In this communication, we study the photospheric magnetic roots of the coronal hole and the coronal mass ejection area with HMI/SDO magnetograms to define their magnetic characteristics.

Triennial Report 2006-2009. Commission 10: Solar Activity

NASA Technical Reports Server (NTRS)

Klimchuk, James A.

2008-01-01

Commission 10 deals with solar activity in all of its forms, ranging from the smallest nanoflares to the largest coronal mass ejections. This report reviews scientific progress over the roughly two-year period ending in the middle of 2008. This has been an exciting time in solar physics, highlighted by the launches of the Hinode and STEREO missions late in 2006. The report is reasonably comprehensive, though it is far from exhaustive. Limited space prevents the inclusion of many significant results. The report is divided into following sections: Photosphere and Chromosphere; Transition Region; Corona and Coronal Heating; Coronal Jets; Flares; Coronal Mass Ejection Initiation; Global Coronal Waves and Shocks; Coronal Dimming; The Link Between Low Coronal CME signatures and Magnetic Clouds; Coronal Mass Ejections in the Heliosphere; and Coronal Mass Ejections and Space Weather. Primary authorship is indicated at the beginning of each section.

Determination of the coronal magnetic field from vector magnetograph data

NASA Technical Reports Server (NTRS)

Mikic, Zoran

1991-01-01

A new algorithm was developed, tested, and applied to determine coronal magnetic fields above solar active regions. The coronal field above NOAA active region AR5747 was successfully estimated on 20 Oct. 1989 from data taken at the Mees Solar Observatory of the Univ. of Hawaii. It was shown that observational data can be used to obtain realistic estimates of coronal magnetic fields. The model has significantly extended the realism with which the coronal magnetic field can be inferred from observations. The understanding of coronal phenomena will be greatly advanced by a reliable technique, such as the one presented, for deducing the detailed spatial structure of the coronal field. The payoff from major current and proposed NASA observational efforts is heavily dependent on the success with which the coronal field can be inferred from vector magnetograms. In particular, the present inability to reliably obtain the coronal field has been a major obstacle to the theoretical advancement of solar flare theory and prediction. The results have shown that the evolutional algorithm can be used to estimate coronal magnetic fields.

The green corona database and the coronal index of solar activity

NASA Astrophysics Data System (ADS)

Minarovjech, M.; Rušin, V.; Saniga, M.

2011-10-01

The green coronal line Fe XIV 530.3 nm ranks amongst the most pronounced emission lines in the visible part of the solar spectrum. Its observations outside solar eclipses started sporadically in 1939 (the Arosa coronal station), being extended, in 1946, to more coronal stations. It was found that the green corona intensities vary with solar cycle, so they are a good candidate to express solar activity in the corona. Several attempts have been made to create a single homogeneous coronal data set from different coronal stations. We will present our homogeneous coronal data set, based on the Lomnický Štít photometric scale. Also, the coronal index of solar activity as created from this database in the period 1939—2010 will be discussed.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fujiki, K.; Tokumaru, M.; Hayashi, K.

We developed an automated prediction technique for coronal holes using potential magnetic field extrapolation in the solar corona to construct a database of coronal holes appearing from 1975 February to 2015 July (Carrington rotations from 1625 to 2165). Coronal holes are labeled with the location, size, and average magnetic field of each coronal hole on the photosphere and source surface. As a result, we identified 3335 coronal holes and found that the long-term distribution of coronal holes shows a similar pattern known as the magnetic butterfly diagram, and polar/low-latitude coronal holes tend to decrease/increase in the last solar minimum relativemore » to the previous two minima.« less

An equatorial coronal hole at solar minimum

NASA Technical Reports Server (NTRS)

Bromage, B. J. I.; DelZanna, G.; DeForest, C.; Thompson, B.; Clegg, J. R.

1997-01-01

The large transequatorial coronal hole that was observed in the solar corona at the end of August 1996 is presented. It consists of a north polar coronal hole called the 'elephant's trunk or tusk'. The observations of this coronal hole were carried out with the coronal diagnostic spectrometer onboard the Solar and Heliospheric Observatory (SOHO). The magnetic field associated with the equatorial coronal hole is strongly connected to that of the active region at its base, resulting in the two features rotating at almost the same rate.

Does correction of preoperative coronal imbalance make a difference in outcomes of adult patients with deformity?

PubMed

Daubs, Michael D; Lenke, Lawrence G; Bridwell, Keith H; Kim, Yongjung J; Hung, Man; Cheh, Gene; Koester, Linda A

2013-03-15

Retrospective study with prospectively collected outcomes data. Determine the significance of coronal balance on spinal deformity surgery outcomes. Sagittal balance has been confirmed as an important radiographic parameter correlating with adult deformity treatment outcomes. The significance of coronal balance on functional outcomes is less clear. Eighty-five patients with more than 4 cm of coronal imbalance who underwent reconstructive spinal surgery were evaluated to determine the significance of coronal balance on functional outcomes as measured with the Oswestry Disability Index (ODI) and Scoliosis Research Society outcomes questionnaires. Sixty-two patients had combined coronal (>4 cm) and sagittal imbalance (>5 cm), while 23 patients had coronal imbalance alone. Postoperatively, 85% of patients demonstrated improved coronal balance. The mean improvement in the coronal C7 plumb line was 26 mm for a mean correction of 42%. The mean preoperative sagittal C7 plumb line in patients with combined coronal and sagittal imbalance was 118 mm (range, 50-310 mm) and improved to a mean 49 mm. The mean preoperative and postoperative ODI scores were 42 (range, 0-90) and 27 (range, 0-78), for a mean improvement of 15 (36%) (P = 0.00001; 95% CI, 12-20). The mean Scoliosis Research Society scores improved by 17 points (29%) (P = 0.00). Younger age (P = 0.008) and improvement in sagittal balance (P = 0.014) were positive predictors for improved ODI scores. Improvement in sagittal balance (P = 0.010) was a positive predictor for improved Scoliosis Research Society scores. In patients with combined coronal and sagittal imbalance, improvement in sagittal balance was the most significant predictor for improved ODI scores (P = 0.009). In patients with preoperative coronal imbalance alone, improvement in coronal balance trended toward, but was not a significant predictor for improved ODI (P = 0.092). Sagittal balance improvement is the strongest predictor of improved outcomes in patients with combined coronal and sagittal imbalance. In patients with coronal imbalance alone, improvement in coronal balance was not a factor for predicting improved functional outcomes.

Coronal magnetohydrodynamic waves and oscillations: observations and quests.

PubMed

Aschwanden, Markus J

2006-02-15

Coronal seismology, a new field of solar physics that emerged over the last 5 years, provides unique information on basic physical properties of the solar corona. The inhomogeneous coronal plasma supports a variety of magnetohydrodynamics (MHD) wave modes, which manifest themselves as standing waves (MHD oscillations) and propagating waves. Here, we briefly review the physical properties of observed MHD oscillations and waves, including fast kink modes, fast sausage modes, slow (acoustic) modes, torsional modes, their diagnostics of the coronal magnetic field, and their physical damping mechanisms. We discuss the excitation mechanisms of coronal MHD oscillations and waves: the origin of the exciter, exciter propagation, and excitation in magnetic reconnection outflow regions. Finally, we consider the role of coronal MHD oscillations and waves for coronal heating, the detectability of various MHD wave types, and we estimate the energies carried in the observed MHD waves and oscillations: Alfvénic MHD waves could potentially provide sufficient energy to sustain coronal heating, while acoustic MHD waves fall far short of the required coronal heating rates.

CORONAL MAGNETIC FIELDS DERIVED FROM SIMULTANEOUS MICROWAVE AND EUV OBSERVATIONS AND COMPARISON WITH THE POTENTIAL FIELD MODEL

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miyawaki, Shun; Nozawa, Satoshi; Iwai, Kazumasa

2016-02-10

We estimated the accuracy of coronal magnetic fields derived from radio observations by comparing them to potential field calculations and the differential emission measure measurements using EUV observations. We derived line-of-sight components of the coronal magnetic field from polarization observations of the thermal bremsstrahlung in the NOAA active region 11150, observed around 3:00 UT on 2011 February 3 using the Nobeyama Radioheliograph at 17 GHz. Because the thermal bremsstrahlung intensity at 17 GHz includes both chromospheric and coronal components, we extracted only the coronal component by measuring the coronal emission measure in EUV observations. In addition, we derived only themore » radio polarization component of the corona by selecting the region of coronal loops and weak magnetic field strength in the chromosphere along the line of sight. The upper limits of the coronal longitudinal magnetic fields were determined as 100–210 G. We also calculated the coronal longitudinal magnetic fields from the potential field extrapolation using the photospheric magnetic field obtained from the Helioseismic and Magnetic Imager. However, the calculated potential fields were certainly smaller than the observed coronal longitudinal magnetic field. This discrepancy between the potential and the observed magnetic field strengths can be explained consistently by two reasons: (1) the underestimation of the coronal emission measure resulting from the limitation of the temperature range of the EUV observations, and (2) the underestimation of the coronal magnetic field resulting from the potential field assumption.« less

Simulations of Emerging Magnetic Flux. II. The Formation of Unstable Coronal Flux Ropes and the Initiation of Coronal Mass Ejections

NASA Technical Reports Server (NTRS)

Leake, James E.; Linton, Mark G.; Antiochos, Spiro K.

2014-01-01

We present results from three-dimensional magnetohydrodynamic simulations of the emergence of a twisted convection zone flux tube into a pre-existing coronal dipole field. As in previous simulations, following the partial emergence of the sub-surface flux into the corona, a combination of vortical motions and internal magnetic reconnection forms a coronal flux rope. Then, in the simulations presented here, external reconnection between the emerging field and the pre-existing dipole coronal field allows further expansion of the coronal flux rope into the corona. After sufficient expansion, internal reconnection occurs beneath the coronal flux rope axis, and the flux rope erupts up to the top boundary of the simulation domain (approximately 36 Mm above the surface).We find that the presence of a pre-existing field, orientated in a direction to facilitate reconnection with the emerging field, is vital to the fast rise of the coronal flux rope. The simulations shown in this paper are able to self-consistently create many of the surface and coronal signatures used by coronal mass ejection (CME) models. These signatures include surface shearing and rotational motions, quadrupolar geometry above the surface, central sheared arcades reconnecting with oppositely orientated overlying dipole fields, the formation of coronal flux ropes underlying potential coronal field, and internal reconnection which resembles the classical flare reconnection scenario. This suggests that proposed mechanisms for the initiation of a CME, such as "magnetic breakout," are operating during the emergence of new active regions.

[Bonding interfaces of three kinds of cements and root canal dentin: a scanning electron microscope observation].

PubMed

Chen, Lei; Lei, Hui-yun; Xu, Guo-fu; Liang, Xiao-peng; Li, Ji-jia

2010-04-01

To compare the bonding properties of three kinds of cements by observing the bonding inteffaces of cements and root canal dentin. 15 extracted mandibular premolars were divided into 3 groups, and were cemented by Rely X luting, Panavia F and Paracore 5 mL, respectively. Each tooth was sectioned into two parts and the dentin-cement interfaces at the coronal, middle and apical parts of the fiber post were oberved by scanning electron microscope (SEM). The length of hybrid layer was also recorded. Hybrid layer was not clearly found in group one, which could be seen on the dentin-cement interfaces of group two and three. Resin tags and lateral adhesives were also observed in group three. From the apical to the coronal part, microgaps seemed gradually smaller in group one, while the hybrid layer became thicker in both group two and three. The total-etch resin cement bounds tightly with dentin, and owns a more superior bonding property than self-etch resin cement and resin modified glass ionomer cement.

Optimizing Global Coronal Magnetic Field Models Using Image-Based Constraints

NASA Technical Reports Server (NTRS)

Jones-Mecholsky, Shaela I.; Davila, Joseph M.; Uritskiy, Vadim

2016-01-01

The coronal magnetic field directly or indirectly affects a majority of the phenomena studied in the heliosphere. It provides energy for coronal heating, controls the release of coronal mass ejections, and drives heliospheric and magnetospheric activity, yet the coronal magnetic field itself has proven difficult to measure. This difficulty has prompted a decades-long effort to develop accurate, timely, models of the field, an effort that continues today. We have developed a method for improving global coronal magnetic field models by incorporating the type of morphological constraints that could be derived from coronal images. Here we report promising initial tests of this approach on two theoretical problems, and discuss opportunities for application.

OPTIMIZING GLOBAL CORONAL MAGNETIC FIELD MODELS USING IMAGE-BASED CONSTRAINTS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jones, Shaela I.; Davila, Joseph M.; Uritsky, Vadim, E-mail: shaela.i.jonesmecholsky@nasa.gov

The coronal magnetic field directly or indirectly affects a majority of the phenomena studied in the heliosphere. It provides energy for coronal heating, controls the release of coronal mass ejections, and drives heliospheric and magnetospheric activity, yet the coronal magnetic field itself has proven difficult to measure. This difficulty has prompted a decades-long effort to develop accurate, timely, models of the field—an effort that continues today. We have developed a method for improving global coronal magnetic field models by incorporating the type of morphological constraints that could be derived from coronal images. Here we report promising initial tests of thismore » approach on two theoretical problems, and discuss opportunities for application.« less

The Dependence of the Peak Velocity of High-Speed Solar Wind Streams as Measured in the Ecliptic by ACE and the STEREO satellites on the Area and Co-latitude of Their Solar Source Coronal Holes.

PubMed

Hofmeister, Stefan J; Veronig, Astrid; Temmer, Manuela; Vennerstrom, Susanne; Heber, Bernd; Vršnak, Bojan

2018-03-01

We study the properties of 115 coronal holes in the time range from August 2010 to March 2017, the peak velocities of the corresponding high-speed streams as measured in the ecliptic at 1 AU, and the corresponding changes of the Kp index as marker of their geoeffectiveness. We find that the peak velocities of high-speed streams depend strongly on both the areas and the co-latitudes of their solar source coronal holes with regard to the heliospheric latitude of the satellites. Therefore, the co-latitude of their source coronal hole is an important parameter for the prediction of the high-speed stream properties near the Earth. We derive the largest solar wind peak velocities normalized to the coronal hole areas for coronal holes located near the solar equator and that they linearly decrease with increasing latitudes of the coronal holes. For coronal holes located at latitudes ≳ 60°, they turn statistically to zero, indicating that the associated high-speed streams have a high chance to miss the Earth. Similarly, the Kp index per coronal hole area is highest for the coronal holes located near the solar equator and strongly decreases with increasing latitudes of the coronal holes. We interpret these results as an effect of the three-dimensional propagation of high-speed streams in the heliosphere; that is, high-speed streams arising from coronal holes near the solar equator propagate in direction toward and directly hit the Earth, whereas solar wind streams arising from coronal holes at higher solar latitudes only graze or even miss the Earth.

Low coronal signatures of coronal mass ejections

NASA Astrophysics Data System (ADS)

Attrill, Gemma Diana Ruth

Coronal mass ejections (CMEs) are vast eruptions of magnetised plasma that explode from the solar atmosphere. This thesis focuses on understanding the nascent stages of CMEs, and their magnetic development as they expand into the interplanetary space of our solar system. This is an important part of our effort to understand the space weather environment that we live in, and increasingly interact with through satellite communications technologies. Predominantly through combining extreme ultra-violet imaging and magnetogram data, two low coronal signatures of CMEs, namely coronal waves and dimmings, are studied. A comprehensive list of observational properties of EIT coronal waves is compiled and potential counterparts in radio, Ha, soft X-rays and He n wavelengths are also discussed. New observational constraints on EIT coronal waves are presented, most notably diffuse coronal waves are shown to have a magnetic nature. Finding that many observational constraints are not satisfactorily explained by current theories, a new model for understanding the physical nature of diffuse coronal waves is developed. The new model interprets diffuse coronal "wave" bright fronts to be the low coronal magnetic footprint of CMEs. Implications for developing our understanding of how CMEs become large-scale in the low corona are discussed. Application of the model demonstrates how an understanding of the formation of complex global-scale coronal dimmings can be derived. For the first time it is shown that study of the evolution and magnetic nature of coronal dimming regions can be used to probe the post-eruptive evolution of the CME. Finally, a study is presented regarding why and how CME-related dimmings recover, despite the "open" magnetic connectivity of the ejecta to the Sun being maintained as indicated by electron heat flux measurements at 1 AU.

Features of solar wind streams on June 21-28, 2015 as a result of interactions between coronal mass ejections and recurrent streams from coronal holes

NASA Astrophysics Data System (ADS)

Shugay, Yu. S.; Slemzin, V. A.; Rod'kin, D. G.

2017-11-01

Coronal sources and parameters of solar wind streams during a strong and prolonged geomagnetic disturbance in June 2015 have been considered. Correspondence between coronal sources and solar wind streams at 1 AU has been determined using an analysis of solar images, catalogs of flares and coronal mass ejections, solar wind parameters including the ionic composition. The sources of disturbances in the considered period were a sequence of five coronal mass ejections that propagated along the recurrent solar wind streams from coronal holes. The observed differences from typical in magnetic and kinetic parameters of solar wind streams have been associated with the interactions of different types of solar wind. The ionic composition has proved to be a good additional marker for highlighting components in a mixture of solar wind streams, which can be associated with different coronal sources.

Intake of energy and nutrients. Euronut SENECA investigators.

PubMed

Moreiras, O; van Staveren, W A; Cruz, J A; Nes, M; Lund-Larsen, K

1991-12-01

As part of the Euronut SENECA study, food consumption has been assessed in 1217 men and 1241 women, born between 1913 and 1918 and living in 18 towns in 12 European countries. The method used was a standardized modified dietary history, including a 3-day estimated record and a food frequency list based on local food patterns. Intakes of energy, protein, fat, carbohydrate, fatty acids, cholesterol and alcohol are described in this paper. As expected, a difference between men and women in energy and nutrient intake was observed in all towns. There was a great variation between towns in mean dietary intakes of all dietary components. Mean energy intake of men ranged from 12.7 MJ in Marki (Poland) to 8.2 MJ in Yverdon (Switzerland) and Chateau Renault-Amboise (France). For women the range was from 10.9 MJ in Marki (Poland) to 6.3 MJ in Yverdon (Switzerland) and Vila Franca de Xira (Portugal). A geographical pattern can be detected for the intake of fatty acids. Intakes of saturated fat were lower in southern than in northern European towns. The calculated ratio for intakes of unsaturated and saturated fatty acids (polyunsaturated fatty acids plus monounsaturated fatty acids/saturated fatty acids) for all participants was higher in the southern European centres than in the northern centres and ranged from 2.7 in Markopoulo (Greece) to 1.2 in Elverum (Norway) and Marki (Poland). Alcohol consumption was considerable higher in men than in women. In men a north-south gradient in alcohol intake can be detected, with the highest intake in the two centres in Italy, where, on average 11% of energy intake was derived from alcohol.

Characteristics of Low-latitude Coronal Holes near the Maximum of Solar Cycle 24

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hofmeister, Stefan J.; Veronig, Astrid; Reiss, Martin A.

We investigate the statistics of 288 low-latitude coronal holes extracted from SDO /AIA-193 filtergrams over the time range of 2011 January 01–2013 December 31. We analyze the distribution of characteristic coronal hole properties, such as the areas, mean AIA-193 intensities, and mean magnetic field densities, the local distribution of the SDO /AIA-193 intensity and the magnetic field within the coronal holes, and the distribution of magnetic flux tubes in coronal holes. We find that the mean magnetic field density of all coronal holes under study is 3.0 ± 1.6 G, and the percentaged unbalanced magnetic flux is 49 ± 16%.more » The mean magnetic field density, the mean unsigned magnetic field density, and the percentaged unbalanced magnetic flux of coronal holes depend strongly pairwise on each other, with correlation coefficients cc > 0.92. Furthermore, we find that the unbalanced magnetic flux of the coronal holes is predominantly concentrated in magnetic flux tubes: 38% (81%) of the unbalanced magnetic flux of coronal holes arises from only 1% (10%) of the coronal hole area, clustered in magnetic flux tubes with field strengths >50 G (10 G). The average magnetic field density and the unbalanced magnetic flux derived from the magnetic flux tubes correlate with the mean magnetic field density and the unbalanced magnetic flux of the overall coronal hole (cc>0.93). These findings give evidence that the overall magnetic characteristics of coronal holes are governed by the characteristics of the magnetic flux tubes.« less

Usefulness of the dynamic gadolinium-enhanced magnetic resonance imaging with simultaneous acquisition of coronal and sagittal planes for detection of pituitary microadenomas.

PubMed

Lee, Han Bee; Kim, Sung Tae; Kim, Hyung-Jin; Kim, Keon Ha; Jeon, Pyoung; Byun, Hong Sik; Choi, Jin Wook

2012-03-01

Does dynamic gadolinium-enhanced imaging with simultaneous acquisition of coronal and sagittal planes improve diagnostic accuracy of pituitary microadenomas compared with coronal images alone? Fifty-six patients underwent 3-T sella MRI including dynamic simultaneous acquisition of coronal and sagittal planes after gadolinium injection. According to conspicuity, lesions were divided into four scores (0, no; 1, possible; 2, probable; 3, definite delayed enhancing lesion). Additional information on supplementary sagittal images compared with coronal ones was evaluated with a 4-point score (0, no; 1, possible; 2, probable; 3, definite additional information). Accuracy of tumour detection was calculated. Average scores for lesion detection of a combination of two planes, coronal, and sagittal images were 2.59, 2.32, and 2.18. 6/10 lesions negative on coronal images were detected on sagittal ones. Accuracy of a combination of two planes, of coronal and of sagittal images was 92.86%, 82.14% and 75%. Six patients had probable or definite additional information on supplementary sagittal images compared with coronal ones alone (10.71%). Dynamic MRI with combined coronal and sagittal planes was more accurate for detection of pituitary microadenomas than routinely used coronal images. Simultaneous dynamic enhanced acquisition can make study time fast and costs low. We present a new dynamic MRI technique for evaluating pituitary microadenomas • This technique provides simultaneous acquisition of contrast enhanced coronal and sagittal images. • This technique makes the diagnosis more accurate and reduces the examination time. • Such MR imaging only requires one single bolus of contrast agent.

Flux Cancelation as the Trigger of Quiet-Region Coronal Jet Eruptions

NASA Technical Reports Server (NTRS)

Panesar, Navdeep K.; Sterling, Alphonse; Moore, Ronald L.

2017-01-01

Coronal jets are frequent magnetically channeled narrow eruptions. They occur in various solar environments: quiet regions, coronal holes and active regions. All coronal jets observed in EUV (Extreme UltraViolet) and X-ray images show a bright spire with a base brightening, also known as jet bright point (JBP). Recent studies show that coronal jets are driven by small-scale filament eruptions. Sterling et al. 2015 did extensive study of 20 polar coronal hole jets and found that X-ray jets are mainly driven by the eruption of minifilaments. What leads to these minifilament eruptions?

Remaking the medico-legal scene: a social history of the late-Victorian coroner in Oxford.

PubMed

Hurren, Elizabeth T

2010-04-01

There have been wide-ranging debates about medicine and the law encapsulated in the figure of the coroner in Victorian England. Recently the historical literature on coroners has been enriched by macro-studies. Despite this important research, the social lives of coroners and their daily interactions remain relatively neglected in standard historical accounts. This article redresses that issue by examining the working life of the coroner for Oxford during the late-Victorian era. Edward Law Hussey kept very detailed records of his time in office as coroner. New research material makes it feasible to trace his professional background, from doctor of the sick poor, to hospital house surgeon and then busy coroner. His career trajectory, personal interactions, and professional disputes, provide an important historical prism illuminating contemporary debates that occupied coroners in their working lives. Hussey tried to improve his medico-legal reach and the public image of his coroner's office by reducing infanticide rates, converting a public mortuary, and acquiring a proper coroner's court. His campaigns had limited success because the social scene in which he worked was complicated by the dominance of health and welfare agencies that resented his role as an expanding arm of the Victorian information state.

Analysis of the gutta-percha filled area in C-shaped mandibular molars obturated with a modified MicroSeal technique.

PubMed

Ordinola-Zapata, R; Bramante, C M; de Moraes, I G; Bernardineli, N; Garcia, R B; Gutmann, J L

2009-03-01

To analyse the gutta-percha filled area of C-shaped molar teeth root filled with the modified MicroSeal technique with reference to the radiographic features and the C-shaped canal configuration. Twenty-three mandibular second molar teeth with C-shaped roots were classified according to their radiographic features as: type I--merging, type II--symmetrical and type III--asymmetrical. The canals were root filled using a modified technique of the MicroSeal system. Horizontal sections at intervals of 600 mum were made 1 mm from the apex to the subpulpal floor level. The percentage of gutta-percha area from the apical, middle and coronal levels of the radiographic types was analysed using the Kruskal-Wallis test. Complementary analysis of the C-shaped canal configurations (C1, C2 and C3) determined from cross-sections from the apical third was performed in a similar way. No significant differences were found between the radiographic types in terms of the percentage of gutta-percha area at any level (P > 0.05): apical third, type I: 77.04%, II: 70.48% and III: 77.13%, middle third, type I: 95.72%, II: 93.17%, III: 91.13% and coronal level, type I: 98.30%, II: 98.25%, III: 97.14%. Overall, the percentage of the filling material was lower in the apical third (P < 0.05). No significant differences were found between the C-shaped canal configurations apically; C1: 72.64%, C2: 79.62%, C3: 73.51% (P > 0.05). The percentage of area filled with gutta-percha was similar in the three radiographic types and canal configuration categories of C-shaped molars. These results show the difficulty of achieving predictable filling of the root canal system when this anatomical variation exists. In general, the apical third was less completely filled.

Analysis and Modeling of Coronal Holes Observed by CORONAS-1. 1; Morphology and Magnetic Field Configuration

NASA Technical Reports Server (NTRS)

Obridko, Vladmir; Formichev, Valery; Kharschiladze, A. F.; Zhitnik, Igor; Slemzin, Vladmir; Hathaway, David H.; Wu, Shi T.

1998-01-01

Two low-latitude coronal holes observed by CORONAS-1 in April and June 1994 are analyzed together with magnetic field measurements obtained from Wilcox and Kitt Peak Solar Observatories. To estimate the comparable temperature of these two coronal holes, the YOHKOH observations are also utilized. Using this information, we have constructed three-dimensional magnetic field lines to illustrate the geometrical configuration of these coronal holes. The calculated synoptic maps are used to determine the existence of closed and open field regions of the hole. Finally, we have correlated the characteristics of two coronal holes with observed solar wind speed. We found that the brighter coronal hole has high speed solar wind, and the dimmer coronal hole has low speed solar wind.

Newborn Coronal Holes Associated with the Disappearance of Polarity Reversal Boundaries (P46)

NASA Astrophysics Data System (ADS)

Shelke, R.

2006-11-01

rajendra_shelke@yahoo.co.in Coronal holes play an important role in the occurrence of various kinds of solar events. The geomagnetic activity, coronal transients, type II radio bursts, and soft X ray blowouts have shown their strong association with coronal holes (Webb et al., 1978; Shelke and Pande, 1985; Bhatnagar, 1996; Hewish and Bravo, 1986). Recently, Shelke (2006) has linked the onset of interplanetary erupting stream disturbances with the evolutionary changes in the coronal holes. The present study reveals that there exists some physical relationship between the formation of new coronal holes and the disappearance of polarity reversal boundaries with or without the overlying prominences. About 124 new coronal holes are found to emerge at the locations where polarity reversal boundaries existed prior to their disappearance. Among them, nearly 66% and 18% newborn coronal holes have been associated with disappearing prominences and disappearing small unipolar magnetic regions (UMRs) with encircled polarity reversal boundaries respectively. Coronal holes and quiescent prominences are stable solar features that last for many solar rotations. A coronal hole is indicative of a radial magnetic field of a predominant magnetic polarity at the photosphere, whereas solar prominence overlying the polarity reversal boundary straddles both the polarities of a bipolar magnetic region. The new coronal hole emerges on the Sun, owing to the changes in magnetic field configuration leading to the opening of closed magnetic structure into the corona. The mechanism that leads to the eruption of polarity reversal boundaries with or without prominences seems to be interlinked with the mechanism that converts bipolar magnetic regions into unipolar magnetic regions characterizing coronal holes. The fundamental activity for the onset of erupting polarity reversal boundary seems to be the opening of preexisting closed magnetic structures into a new coronal hole, which can support mass motion including erupting prominence.

The role of the large-scale coronal magnetic field in the eruption of prominence/cavity systems

NASA Astrophysics Data System (ADS)

de Toma, G.; Gibson, S. E.; Fan, Y.; Torok, T.

2013-12-01

Prominence/cavity systems are large-scale coronal structures that can live for many weeks and even months and often end their life in the form of large coronal eruptions. We investigate the role of the surrounding ambient coronal field in stabilizing these systems against eruption. In particular, we examine the extent to which the decline with height of the external coronal magnetic field influences the evolution of these coronal systems and their likelihood to erupt. We study prominence/cavity systems during the rising phase of cycle 24 in 2010-2013, when a significant number of CMEs were associated with polar crown or large filament eruptions. We use EUV observations from SDO/AIA to identify stable and eruptive coronal cavities, and SDO/HMI magnetograms as boundary conditions to PFSS extrapolation to derive the ambient coronal field. We compute the decay index of the potential field for the two groups and find that systematic differences exist between eruptive and non-eruptive systems.

Observational features of equatorial coronal hole jets

NASA Astrophysics Data System (ADS)

Nisticò, G.; Bothmer, V.; Patsourakos, S.; Zimbardo, G.

2010-03-01

Collimated ejections of plasma called "coronal hole jets" are commonly observed in polar coronal holes. However, such coronal jets are not only a specific features of polar coronal holes but they can also be found in coronal holes appearing at lower heliographic latitudes. In this paper we present some observations of "equatorial coronal hole jets" made up with data provided by the STEREO/SECCHI instruments during a period comprising March 2007 and December 2007. The jet events are selected by requiring at least some visibility in both COR1 and EUVI instruments. We report 15 jet events, and we discuss their main features. For one event, the uplift velocity has been determined as about 200 km s-1, while the deceleration rate appears to be about 0.11 km s-2, less than solar gravity. The average jet visibility time is about 30 min, consistent with jet observed in polar regions. On the basis of the present dataset, we provisionally conclude that there are not substantial physical differences between polar and equatorial coronal hole jets.

Hanle Effect Diagnostics of the Coronal Magnetic Field: A Test Using Realistic Magnetic Field Configurations

NASA Astrophysics Data System (ADS)

Raouafi, N.-E.; Solanki, S. K.; Wiegelmann, T.

2009-06-01

Our understanding of coronal phenomena, such as coronal plasma thermodynamics, faces a major handicap caused by missing coronal magnetic field measurements. Several lines in the UV wavelength range present suitable sensitivity to determine the coronal magnetic field via the Hanle effect. The latter is a largely unexplored diagnostic of coronal magnetic fields with a very high potential. Here we study the magnitude of the Hanle-effect signal to be expected outside the solar limb due to the Hanle effect in polarized radiation from the H I Lyα and β lines, which are among the brightest lines in the off-limb coronal FUV spectrum. For this purpose we use a magnetic field structure obtained by extrapolating the magnetic field starting from photospheric magnetograms. The diagnostic potential of these lines for determining the coronal magnetic field, as well as their limitations are studied. We show that these lines, in particular H I Lyβ, are useful for such measurements.

Relative coronal abundances derived from X-ray observations 3: The effect of cascades on the relative intensity of Fe (XVII) line fluxes, and a revised iron abundance

NASA Technical Reports Server (NTRS)

Walker, A. B. C., Jr.; Rugge, H. R.; Weiss, K.

1974-01-01

Permitted lines in the optically thin coronal X-ray spectrum were analyzed to find the distribution of coronal material, as a function of temperature, without special assumptions concerning coronal conditions. The resonance lines of N, O, Ne, Na, Mg, Al, Si, S, and Ar which dominate the quiet coronal spectrum below 25A were observed. Coronal models were constructed and the relative abundances of these elements were determined. The intensity in the lines of the 2p-3d transitions near 15A was used in conjunction with these coronal models, with the assumption of coronal excitation, to determine the Fe XVII abundance. The relative intensities of the 2p-3d Fe XVII lines observed in the corona agreed with theoretical prediction. Using a more complete theoretical model, and higher resolution observations, a revised calculation of iron abundance relative to hydrogen of 0.000026 was made.

Further Evaluations of Collateral Damage

DTIC Science & Technology

1978-09-29

delivered Rockeye weapons. Basic input data are taken from JMEM. The AIDA model is used for various numbers of Rockeyes to determine the number associated...TANDEM-C data base was further processed to provide population data in square cells 250m on a side. This data base can be directly input into the AIDA ... model and can be modified for input to M1JHM and RBM. Figure 1 gives the general area with town outlines, P-95 circles and population data and Figure 2

Invisibility of Solar Active Region Umbra-to-Umbra Coronal Loops: New Evidence that Magnetoconvection Drives Solar-Stellar Coronal Heating

NASA Technical Reports Server (NTRS)

Tiwari, Sanjiv K.; Thalmann, Julia K.; Panesar, Navdeep K.; Moore, Ronald L.; Winebarger, Amy R.

2017-01-01

Coronal heating generally increases with increasing magnetic field strength: the EUV/X-ray corona in active regions is 10--100 times more luminous and 2--4 times hotter than that in quiet regions and coronal holes, which are heated to only about 1.5 MK, and have fields that are 10--100 times weaker than that in active regions. From a comparison of a nonlinear force-free model of the three-dimensional active region coronal field to observed extreme-ultraviolet loops, we find that (1) umbra-to-umbra coronal loops, despite being rooted in the strongest magnetic flux, are invisible, and (2) the brightest loops have one foot in an umbra or penumbra and the other foot in another sunspot's penumbra or in unipolar or mixed-polarity plage. The invisibility of umbra-to-umbra loops is new evidence that magnetoconvection drives solar-stellar coronal heating: evidently, the strong umbral field at both ends quenches the magnetoconvection and hence the heating. Our results from EUV observations and nonlinear force-free modeling of coronal magnetic field imply that, for any coronal loop on the Sun or on any other convective star, as long as the field can be braided by convection in at least one loop foot, the stronger the field in the loop, the stronger the coronal heating.

Effect of the Coronal Wall Thickness of Dental Implants on the Screw Joint Stability in the Internal Implant-Abutment Connection.

PubMed

Lee, Ji-Hye; Huh, Yoon-Hyuk; Park, Chan-Jin; Cho, Lee-Ra

2016-01-01

To evaluate the effect of implant coronal wall thickness on load-bearing capacity and screw joint stability. Experimental implants were customized after investigation of the thinnest coronal wall thickness of commercially available implant systems with a regular platform diameter. Implants with four coronal wall thicknesses (0.2, 0.3, 0.4, and 0.5 mm) were fabricated. Three sets of tests were performed. The first set was a failure test to evaluate load-bearing capacity and elastic limit. The second and third sets were cyclic and static loading tests. After abutment screw tightening of each implant, vertical cyclic loading of 250 N or static loading from 250 to 800 N was applied. Coronal diameter expansion, axial displacement, and removal torque values of the implants were compared. Repeated measures analysis of variance (ANOVA) was used for statistical analysis (α = .05). Implants with 0.2-mm coronal wall thickness demonstrated significantly low load-bearing capacity and elastic limit (both P < .05). These implants also showed significantly large coronal diameter expansion and axial displacement after screw tightening (both P < .05). Greater vertical load and thinner coronal wall thickness significantly increased coronal diameter expansion of the implant, axial displacement of the abutment, and removal torque loss of the abutment screw (all P < .05). Implant coronal wall thickness of 0.2 mm produces significantly inferior load-bearing capacity and screw joint stability.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Antolin, P.; Rouppe van der Voort, L., E-mail: patrick.antolin@astro.uio.no, E-mail: v.d.v.l.rouppe@astro.uio.no

Observed in cool chromospheric lines, such as H{alpha} or Ca II H, coronal rain corresponds to cool and dense plasma falling from coronal heights. Considered as a peculiar sporadic phenomenon of active regions, it has not received much attention since its discovery more than 40 years ago. Yet, it has been shown recently that a close relationship exists between this phenomenon and the coronal heating mechanism. Indeed, numerical simulations have shown that this phenomenon is most likely due to a loss of thermal equilibrium ensuing from a heating mechanism acting mostly toward the footpoints of loops. We present here onemore » of the first high-resolution spectroscopic observations of coronal rain, performed with the CRisp Imaging Spectro Polarimeter (CRISP) instrument at the Swedish Solar Telescope. This work constitutes the first attempt to assess the importance of coronal rain in the understanding of the coronal magnetic field in active regions. With the present resolution, coronal rain is observed to literally invade the entire field of view. A large statistical set is obtained in which dynamics (total velocities and accelerations), shapes (lengths and widths), trajectories (angles of fall of the blobs), and thermodynamic properties (temperatures) of the condensations are derived. Specifically, we find that coronal rain is composed of small and dense chromospheric cores with average widths and lengths of {approx}310 km and {approx}710 km, respectively, average temperatures below 7000 K, displaying a broad distribution of falling speeds with an average of {approx}70 km s{sup -1}, and accelerations largely below the effective gravity along loops. Through estimates of the ion-neutral coupling in the blobs we show that coronal rain acts as a tracer of the coronal magnetic field, thus supporting the multi-strand loop scenario, and acts as a probe of the local thermodynamic conditions in loops. We further elucidate its potential in coronal heating. We find that the cooling in neighboring strands occurs simultaneously in general suggesting a similar thermodynamic evolution among strands, which can be explained by a common footpoint heating process. Constraints for coronal heating models of loops are thus provided. Estimates of the fraction of coronal volume with coronal rain give values between 7% and 30%. Estimates of the occurrence time of the phenomenon in loops set times between 5 and 20 hr, implying that coronal rain may be a common phenomenon, in agreement with the frequent observations of cool downflows in extreme-ultraviolet lines. The coronal mass drain rate in the form of coronal rain is estimated to be on the order of 5 Multiplication-Sign 10{sup 9} g s{sup -1}, a significant quantity compared to the estimate of mass flux into the corona from spicules.« less

Fault lines in forensic medical toxicology in Ireland exposed through replies of pathologists and coroners to anonymous questionnaires.

PubMed

Tormey, William P; Borovickova, Ingrid; Moore, Tara M

2014-01-01

The attitudes and experiences of pathologists and coroners to the provision of biochemical forensic toxicology in the Republic of Ireland were determined using separate questionnaires to each group anonymously. Replies were received from 36/88 (41%) of pathologists and 19/71 (27%) of coroners. 37% of coroners considered that histopathologists give an adequate opinion in forensic toxicology yet 58% of pathologists reported that they did not have adequate access to expert medical interpretative toxicological opinion. For drug-drug interactions and metabolic diseases, 69% of pathologists were unhappy with the processes and 68% of coroner replies did not know if vitreous samples were used appropriately. There is a clear requirement for retraining of coroners and for the appointment of medical toxicology expertise to improve the quality of service for coroners.

Unresolved fine-scale structure in solar coronal loop-tops

DOE Office of Scientific and Technical Information (OSTI.GOV)

Scullion, E.; Van der Voort, L. Rouppe; Wedemeyer, S.

2014-12-10

New and advanced space-based observing facilities continue to lower the resolution limit and detect solar coronal loops in greater detail. We continue to discover even finer substructures within coronal loop cross-sections, in order to understand the nature of the solar corona. Here, we push this lower limit further to search for the finest coronal loop substructures, through taking advantage of the resolving power of the Swedish 1 m Solar Telescope/CRisp Imaging Spectro-Polarimeter (CRISP), together with co-observations from the Solar Dynamics Observatory/Atmospheric Image Assembly (AIA). High-resolution imaging of the chromospheric Hα 656.28 nm spectral line core and wings can, under certainmore » circumstances, allow one to deduce the topology of the local magnetic environment of the solar atmosphere where its observed. Here, we study post-flare coronal loops, which become filled with evaporated chromosphere that rapidly condenses into chromospheric clumps of plasma (detectable in Hα) known as a coronal rain, to investigate their fine-scale structure. We identify, through analysis of three data sets, large-scale catastrophic cooling in coronal loop-tops and the existence of multi-thermal, multi-stranded substructures. Many cool strands even extend fully intact from loop-top to footpoint. We discover that coronal loop fine-scale strands can appear bunched with as many as eight parallel strands within an AIA coronal loop cross-section. The strand number density versus cross-sectional width distribution, as detected by CRISP within AIA-defined coronal loops, most likely peaks at well below 100 km, and currently, 69% of the substructure strands are statistically unresolved in AIA coronal loops.« less

Accuracy and reliability of coronal and sagittal spinal curvature data based on patient-specific three-dimensional models created by the EOS 2D/3D imaging system.

PubMed

Somoskeöy, Szabolcs; Tunyogi-Csapó, Miklós; Bogyó, Csaba; Illés, Tamás

2012-11-01

Three-dimensional (3D) deformations of the spine are predominantly characterized by two-dimensional (2D) angulation measurements in coronal and sagittal planes, using anteroposterior and lateral X-ray images. For coronal curves, a method originally described by Cobb and for sagittal curves a modified Cobb method are most widely used in practice, and these methods have been shown to exhibit good-to-excellent reliability and reproducibility, carried out either manually or by computer-based tools. Recently, an ultralow radiation dose-integrated radioimaging solution was introduced with special software for realistic 3D visualization and parametric characterization of the spinal column. Comparison of accuracy, correlation of measurement values, intraobserver and interrater reliability of methods by conventional manual 2D and sterEOS 3D measurements in a routine clinical setting. Retrospective nonrandomized study of diagnostic X-ray images created as part of a routine clinical protocol of eligible patients examined at our clinic during a 30-month period between July 2007 and December 2009. In total, 201 individuals (170 females, 31 males; mean age, 19.88 years) including 10 healthy athletes with normal spine and patients with adolescent idiopathic scoliosis (175 cases), adult degenerative scoliosis (11 cases), and Scheuermann hyperkyphosis (5 cases). Overall range of coronal curves was between 2.4° and 117.5°. Analysis of accuracy and reliability of measurements were carried out on a group of all patients and in subgroups based on coronal plane deviation: 0° to 10° (Group 1, n=36), 10° to 25° (Group 2, n=25), 25° to 50° (Group 3, n=69), 50° to 75° (Group 4, n=49), and more than 75° (Group 5, n=22). Coronal and sagittal curvature measurements were determined by three experienced examiners, using either traditional 2D methods or automatic measurements based on sterEOS 3D reconstructions. Manual measurements were performed three times, and sterEOS 3D reconstructions and automatic measurements were performed two times by each examiner. Means comparison t test, Pearson bivariate correlation analysis, reliability analysis by intraclass correlation coefficients for intraobserver reproducibility and interrater reliability were performed using SPSS v16.0 software (IBM Corp., Armonk, NY, USA). No funds were received in support of this work. No benefits in any form have been or will be received from a commercial party related directly or indirectly to the subject of this article. In comparison with manual 2D methods, only small and nonsignificant differences were detectable in sterEOS 3D-based curvature data. Intraobserver reliability was excellent for both methods, and interrater reproducibility was consistently higher for sterEOS 3D methods that was found to be unaffected by the magnitude of coronal curves or sagittal plane deviations. This is the first clinical report on EOS 2D/3D system (EOS Imaging, Paris, France) and its sterEOS 3D software, documenting an excellent capability for accurate, reliable, and reproducible spinal curvature measurements. Copyright © 2012 Elsevier Inc. All rights reserved.

77 FR 24537 - Draft Standards and Best Practices for Interaction Between Medical Examiner/Coroner and Organ and...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-04-24

... Best Practices for Interaction Between Medical Examiner/Coroner and Organ and Tissue Procurement... Committee Standards and Best Practices for Interaction Between Medical Examiner/Coroner Offices and Organ... coroner/medical examiner office representatives, law enforcement agencies, organizations, and all other...

Coronal holes as sources of solar wind

NASA Technical Reports Server (NTRS)

Nolte, J. T.; Krieger, A. S.; Timothy, A. F.; Gold, R. E.; Roelof, E. C.; Vaiana, G.; Lazarus, A. J.; Sullivan, J. D.; Mcintosh, P. S.

1976-01-01

We investigate the association of high-speed solar wind with coronal holes during the Skylab mission by: (1) direct comparison of solar wind and coronal X-ray data; (2) comparison of near-equatorial coronal hole area with maximum solar wind velocity in the associated streams; and (3) examination of the correlation between solar and interplanetary magnetic polarities. We find that all large near-equatorial coronal holes seen during the Skylab period were associated with high-velocity solar wind streams observed at 1 AU.

Repeated Structures Found After the Solar Maximum in the Butterfly Diagrams of Coronal Holes

NASA Astrophysics Data System (ADS)

Hofer, M. Y.; Storini, M.

2003-09-01

The influence of the solar cycle evolution on the coronal hole space-time distribution is well known, for polar as well as for equatorial isolated sources of high speed solar wind. Among them the long-lived coronal holes occurrence from the sunspot cycle 21 on is investigated, using the coronal hole catalogue based on HeI (1083 nm) observations (Sanchez-Ibarra and Barraza-Paredes). In at least these two solar cycles (n. 21 and n. 22) a similar structure in the latitude-time diagram of coronal holes is found. The area occurs shortly after the solar maximum at around ~35° heliolatitude and consists of over several Carrington Rotations stable coronal holes (>5 Carr. Rot.s). The diagonal disappears 2-3 years later at the helioequator. Furthermore, the analysis results in a close relation between long-lived isolated coronal holes and the soft X-class flares.

Coroners and death certification law reform: the Coroners and Justice Act 2009 and its aftermath.

PubMed

Luce, Tom

2010-10-01

After considering various different options for half a decade, the last Government legislated in 2009 to reform the England and Wales coroner and death certification systems. The Coroners and Justice Act 2009 provides for the creation of a new Chief Coroner post to lead the jurisdiction and for local medical examiners to oversee a new death certification scheme applicable equally to burial and cremation cases. In October 2010 the new Government announced that it judges the main coroner reform to be unaffordable, will not proceed with it and plans to repeal the provisions. It intends to implement the new death certification arrangements, which is welcome. The decision to abort the main coroner reform in spite of longstanding and widespread recognition of the need for major change is deplorable though in line with other failures over the last century to properly modernise this neglected service.

Disruption of a coronal streamer by an eruptive prominence and coronal mass ejection

NASA Technical Reports Server (NTRS)

Illing, R. M. E.; Hundhausen, A. J.

1986-01-01

The coronal mass ejection of August 18, 1980 is analyzed using images from the coronagraph on the Solar Maximum Mission (SMM) satellite. The event occurred at the site of a large coronal helmet streamer and evolved into the three-part structure of a bright frontal shell, followed by a relatively dark space surrounding a bright filamentary core as seen in many mass ejections of the SMM epoch. The bright core can be identified as material from a prominence whose eruption was observed from the ground. The mass of the frontal shell is equal to that of the coronal helmet streamer, indicating that the shell is the coronal material previously in the helmet streamer, displaced and set into motion by the erupting prominence and surrounding cavity. The mass ejected in the bright core (or prominences) is estimated to be 50 percent larger than the 'coronal' material in the front loop.

The Coronal Solar Magnetism Observatory

NASA Astrophysics Data System (ADS)

Tomczyk, S.; Landi, E.; Zhang, J.; Lin, H.; DeLuca, E. E.

2015-12-01

Measurements of coronal and chromospheric magnetic fields are arguably the most important observables required for advances in our understanding of the processes responsible for coronal heating, coronal dynamics and the generation of space weather that affects communications, GPS systems, space flight, and power transmission. The Coronal Solar Magnetism Observatory (COSMO) is a proposed ground-based suite of instruments designed for routine study of coronal and chromospheric magnetic fields and their environment, and to understand the formation of coronal mass ejections (CME) and their relation to other forms of solar activity. This new facility will be operated by the High Altitude Observatory of the National Center for Atmospheric Research (HAO/NCAR) with partners at the University of Michigan, the University of Hawaii and George Mason University in support of the solar and heliospheric community. It will replace the current NCAR Mauna Loa Solar Observatory (http://mlso.hao.ucar.edu). COSMO will enhance the value of existing and new observatories on the ground and in space by providing unique and crucial observations of the global coronal and chromospheric magnetic field and its evolution. The design and current status of the COSMO will be reviewed.

Main Properties of Forbush Effects Related to High-Speed Streams from Coronal Holes

NASA Astrophysics Data System (ADS)

Melkumyan, A. A.; Belov, A. V.; Abunina, M. A.; Abunin, A. A.; Eroshenko, E. A.; Oleneva, V. A.; Yanke, V. G.

2018-03-01

The IZMIRAN database of Forbush effects and interplanetary disturbances was used to study features of the action of high-speed solar wind streams from coronal holes on cosmic rays. Three hundred and fifty Forbush effects created by coronal holes without other actions were distinguished. The mean values and distributions have been found for different characteristics of events from this group and compared with all Forbush effects and Forbush effects caused by coronal ejections. Despite the great differences in high-speed streams from coronal holes, this group turned out to be more compact and uniform as compared to events related to coronal ejections. Regression dependences and correlation relations between different parameters of events for the studied groups have been obtained. It has been shown that Forbush effects caused by coronal ejections depend considerably more strongly on the characteristics of interplanetary disturbances as compared to Forbush effects related to coronal holes. This suggests a significant difference between the modulation mechanisms of Forbush effects of different types and corroborates earlier conclusions based on indirect data.

On the structure of solar and stellar coronae - Loops and loop heat transport

NASA Technical Reports Server (NTRS)

Litwin, Christof; Rosner, Robert

1993-01-01

We discuss the principal constraints on mechanisms for structuring and heating the outer atmospheres - the coronae - of stars. We argue that the essential cause of highly localized heating in the coronae of stars like the sun is the spatially intermittent nature of stellar surface magnetic fields, and that the spatial scale of the resulting coronal structures is related to the spatial structure of the photospheric fields. We show that significant constraints on coronal heating mechanisms derive from the observed variations in coronal emission, and, in addition, show that the observed structuring perpendicular to coronal magnetic fields imposes severe constraints on mechanisms for heat dispersal in the low-beta atmosphere. In particular, we find that most of commonly considered mechanisms for heat dispersal, such as anomalous diffusion due to plasma turbulence or magnetic field line stochasticity, are much too slow to account for the observed rapid heating of coronal loops. The most plausible mechanism appears to be reconnection at the interface between two adjacent coronal flux bundles. Based on a model invoking hyperresistivity, we show that such a mechanism naturally leads to dominance of isolated single bright coronal loops and to bright coronal plasma structures whose spatial scale transverse to the local magnetic field is comparable to observed dimensions of coronal X-ray loops.

The study of Equatorial coronal hole during maximum phase of Solar Cycle 21, 22, 23 and 24

NASA Astrophysics Data System (ADS)

Karna, Mahendra; Karna, Nishu

2017-08-01

The 11-year Solar Cycle (SC) is characterized by the periodic change in the solar activity like sunspot numbers, coronal holes, active regions, eruptions such as flares and coronal mass ejections. We study the relationship between equatorial coronal holes (ECH) and the active regions (AR) as coronal whole positions and sizes change with the solar cycle. We made a detailed study of equatorial coronal hole for four solar maximum: Solar Cycle 21 (1979,1980,1981 and 1982), Solar Cycle 22 (1989, 1990, 1991 and 1992), Solar Cycle 23 (1999, 2000, 2001 and 2002) and Solar Cycle 24 (2012, 2013, 2014 and 2015). We used publically available NOAA solar coronal hole data for cycle 21 and 22. We measured the ECH region using the EIT and AIA synoptic map for cycle 23 and 24. We noted that in two complete 22-year cycle of solar activity, the equatorial coronal hole numbers in SC 22 is greater than SC 21 and similarly, SC 24 equatorial coronal hole numbers are greater than SC 23. Moreover, we also compared the position of AR and ECH during SC 23 and 24. We used daily Solar Region Summary (SRS) data from SWPC/NOAA website. Our goal is to examine the correlation between equatorial holes, active regions, and flares.

Urban Policies and Earthquake Risk Mitigation

NASA Astrophysics Data System (ADS)

Sarlo, Antonella

2008-07-01

The paper aims at proposing some considerations about some recent experiences of research carried out on the theme of earthquake risk mitigation and combining policies and actions of mitigation with urban development strategies. The objective was to go beyond the classical methodological approach aiming at defining a "technical" evaluation of the earthquake risk through a procedure which can correlate the three "components" of danger, exposure and vulnerability. These researches experiment, in terms of methodology and application, with a new category of interpretation and strategy: the so-called Struttura Urbana Minima (Minimum urban structure). Actually, the introduction of the Struttura Urbana Minima establishes a different approach towards the theme of safety in the field of earthquake risk, since it leads to a wider viewpoint, combining the building aspect of the issue with the purely urban one, involving not only town planning, but also social and managerial implications. In this sense the constituent logic of these researches is strengthened by two fundamental issues: - The social awareness of earthquake; - The inclusion of mitigation policies in the ordinary strategies for town and territory management. Three main aspects of the first point, that is of the "social awareness of earthquake", characterize this issue and demand to be considered within a prevention policy: - The central role of the risk as a social production, - The central role of the local community consent, - The central role of the local community capability to plan Therefore, consent, considered not only as acceptance, but above all as participation in the elaboration and implementation of choices, plays a crucial role in the wider issue of prevention policies. As far as the second point is concerned, the inclusion of preventive mitigation policies in ordinary strategies for the town and territory management demands the identification of criteria of choice and priorities of intervention and, as a consequence, the opportunity to promote an approach to the theme of mitigation policies realized through strategic principles and systemic logics able to shift the problem from the building to the town. The critical aspects of this theme are tied to three main issues: - The sharing of the way of interpreting town planning, - The integration of multiple objectives in one intervention tool, - The measures which can be adopted for an effective prevention policy. The above-mentioned elements have inspired these researches experimented on Calabrian towns. In particular, in this paper the experience carried out on Reggio Calabria is proposed. Its cultural roots derive from the principles and criteria experimented in small Calabrian towns, but it modifies them according to the complexity of the urban settlement, introducing also some experimental concepts and methodological approaches.

Wing geometry of Culex coronator (Diptera: Culicidae) from South and Southeast Brazil

PubMed Central

2014-01-01

Background The Coronator Group encompasses Culex coronator Dyar & Knab, Culex camposi Dyar, Culex covagarciai Forattini, Culex ousqua Dyar, Culex usquatissimus Dyar, Culex usquatus Dyar and Culex yojoae Strickman. Culex coronator has the largest geographic distribution, occurring in North, Central and South America. Moreover, it is a potential vector-borne mosquito species because females have been found naturally infected with several arboviruses, i.e., Saint Louis Encephalitis Virus, Venezuelan Equine Encephalitis Virus and West Nile Virus. Considering the epidemiological importance of Cx. coronator, we investigated the wing shape diversity of Cx. coronator from South and Southeast Brazil, a method to preliminarily estimate population diversity. Methods Field-collected immature stages of seven populations from a large geographical area in Brazil were maintained in the laboratory to obtain both females and males linked with pupal and/or larval exuviae. For each individual female, 18 landmarks of left wings were marked and digitalized. After Procrustes superimposition, discriminant analysis of shape was employed to quantify wing shape variation among populations. The isometric estimator centroid size was calculated to assess the overall wing size and allometry. Results Wing shape was polymorphic among populations of Cx. coronator. However, dissimilarities among populations were higher than those observed within each population, suggesting populational differentiation in Cx. coronator. Morphological distances between populations were not correlated to geographical distances, indicating that other factors may act on wing shape and thus, determining microevolutionary patterns in Cx. coronator. Despite the population differentiation, intrapopulational wing shape variability was equivalent among all seven populations. Conclusion The wing variability found in Cx. coronator populations brings to light a new biological problem to be investigated: the population genetics of Cx. coronator. Because of differences in the male genitalia, we also transferred Cx. yojoae to the Apicinus Subgroup. PMID:24721508

DOE Office of Scientific and Technical Information (OSTI.GOV)

Antolin, P.; Vissers, G.; Shibata, K., E-mail: antolin@astro.uio.n, E-mail: g.j.m.vissers@astro.uio.n, E-mail: shibata@kwasan.kyoto-u.ac.j

Reported observations in H{alpha}, Ca II H, and K or other chromospheric lines of coronal rain trace back to the days of the Skylab mission. Corresponding to cool and dense plasma, coronal rain is often observed falling down along coronal loops in active regions. A physical explanation for this spectacular phenomenon has been put forward thanks to numerical simulations of loops with footpoint-concentrated heating, a heating scenario in which cool condensations naturally form in the corona. This effect has been termed 'catastrophic cooling' and is the predominant explanation for coronal rain. In this work, we further investigate the link betweenmore » this phenomenon and the heating mechanisms acting in the corona. We start by analyzing observations of coronal rain at the limb in the Ca II H line performed by the Hinode satellite, and derive interesting statistical properties concerning the dynamics. We then compare the observations with 1.5-dimensional MHD simulations of loops being heated by small-scale discrete events concentrated toward the footpoints (that could come, for instance, from magnetic reconnection events), and by Alfven waves generated at the photospheric level. Both our observation and simulation results suggest that coronal rain is a far more common phenomenon than previously thought. Also, we show that the structure and dynamics of condensations are far more sensitive to the internal pressure changes in loops than to gravity. Furthermore, it is found that if a loop is predominantly heated from Alfven waves, coronal rain is inhibited due to the characteristic uniform heating they produce. Hence, coronal rain may not only point to the spatial distribution of the heating in coronal loops but also to the agent of the heating itself. We thus propose coronal rain as a marker for coronal heating mechanisms.« less

Using coronal seismology to estimate the magnetic field strength in a realistic coronal model

NASA Astrophysics Data System (ADS)

Chen, F.; Peter, H.

2015-09-01

Aims: Coronal seismology is used extensively to estimate properties of the corona, e.g. the coronal magnetic field strength is derived from oscillations observed in coronal loops. We present a three-dimensional coronal simulation, including a realistic energy balance in which we observe oscillations of a loop in synthesised coronal emission. We use these results to test the inversions based on coronal seismology. Methods: From the simulation of the corona above an active region, we synthesise extreme ultraviolet emission from the model corona. From this, we derive maps of line intensity and Doppler shift providing synthetic data in the same format as obtained from observations. We fit the (Doppler) oscillation of the loop in the same fashion as done for observations to derive the oscillation period and damping time. Results: The loop oscillation seen in our model is similar to imaging and spectroscopic observations of the Sun. The velocity disturbance of the kink oscillation shows an oscillation period of 52.5 s and a damping time of 125 s, which are both consistent with the ranges of periods and damping times found in observations. Using standard coronal seismology techniques, we find an average magnetic field strength of Bkink = 79 G for our loop in the simulation, while in the loop the field strength drops from roughly 300 G at the coronal base to 50 G at the apex. Using the data from our simulation, we can infer what the average magnetic field derived from coronal seismology actually means. It is close to the magnetic field strength in a constant cross-section flux tube, which would give the same wave travel time through the loop. Conclusions: Our model produced a realistic looking loop-dominated corona, and provides realistic information on the oscillation properties that can be used to calibrate and better understand the result from coronal seismology. A movie associated with Fig. 1 is available in electronic form at http://www.aanda.org

Interspecific competition of a new invasive mosquito, Culex coronator, and two container mosquitoes, Aedes albopictus and Cx. quinquefasciatus (Diptera: Culicidae), across different detritus environments.

PubMed

Yee, D A; Skiff, J F

2014-01-01

The mosquito Culex coronator (Dyar and Knab) (Diptera: Culicidae) has undergone rapid range expansion in the United States since 2003, with its historical distribution in the southwest expanding eastward to the Atlantic coast. Although Cx. coronator nominally use small natural aquatic habitats for development, the use of containers (e.g., tires) makes it potentially important as container invasive. To determine the potential ecological effects of Cx. coronator on resident container species, we conducted a laboratory experiment to assess its competitive ability with two common tire-inhabiting species, Aedes albopictus (Skuse) and Culex quinquefasciatus (Say) (Diptera: Culicidae). Larvae were reared under a factorial design with each species alone and in combination (Cx. coronator + Ae. albopictus, Cx. coronator + Cx. quinquefasciatus) across three different resource environments (leaf detritus only, animal detritus only, animal + leaf). Mosquito performance (survival, adult male and female mass, and development time) was measured for each species across treatments. Female Cx. coronator developed slowest when grown with Ae. albopictus, or when grown with leaves only regardless of species combinations; similar patterns emerged for males although species effects were restricted to mass. Few differences were evident in performance for male and female Cx. coronator across detritus environments when grown with Cx. quinquefasciatus. Cx. quinquefasciatus did not vary in mass or development time in the presence of Cx. coronator compared with when grown alone. Ae. albopictus female mass was 15% lower in the presence of Cx. coronator. Survival of Cx. coronator was highest in animal and leaf detritus containers, although survival was generally lower when larvae were grown with Ae. albopictus. These findings suggest that the performance of Cx. coronator is similar to that of Cx. quinquefasciatus but it suffers in the presence of Ae. albopictus under some resource environments.

Determination of Coronal Magnetic Fields from Vector Magnetograms

NASA Technical Reports Server (NTRS)

Mikic, Zoran

1997-01-01

During the course of the present contract we developed an 'evolutionary technique' for the determination of force-free coronal magnetic fields from vector magnetograph observations. The method can successfully generate nonlinear force- free fields (with non-constant-a) that match vector magnetograms. We demonstrated that it is possible to determine coronal magnetic fields from photospheric measurements, and we applied it to vector magnetograms of active regions. We have also studied theoretical models of coronal fields that lead to disruptions. Specifically, we have demonstrated that the determination of force-free fields from exact boundary data is a well-posed mathematical problem, by verifying that the computed coronal field agrees with an analytic force-free field when boundary data for the analytic field are used; demonstrated that it is possible to determine active-region coronal magnetic fields from photospheric measurements, by computing the coronal field above active region 5747 on 20 October 1989, AR6919 on 15 November 1991, and AR7260 on 18 August 1992, from data taken with the Stokes Polarimeter at Mees Solar Observatory, University of Hawaii; started to analyze active region 7201 on 19 June 1992 using measurements made with the Advanced Stokes Polarimeter at NSO/Sac Peak; investigated the effects of imperfections in the photospheric data on the computed coronal magnetic field; documented the coronal field structure of AR5747 and compared it to the morphology of footpoint emission in a flare, showing that the 'high- pressure' H-alpha footpoints are connected by coronal field lines; shown that the variation of magnetic field strength along current-carrying field lines is significantly different from the variation in a potential field, and that the resulting near-constant area of elementary flux tubes is consistent with observations; begun to develop realistic models of coronal fields which can be used to study flare trigger mechanisms; demonstrated that magnetic nonequilibrium can disrupt sheared coronal arcades, and that helmet streamers can disrupt, leading to coronal mass ejections. Our model has significantly extended the realism with which the coronal magnetic field can be inferred from actual observations. In a subsequent contract awarded by NASA, we have continued to apply and improve the evolutionary technique, to study the physical properties of active regions, and to develop theoretical models of magnetic fields.

Large-Scale Coronal Heating, Clustering of Coronal Bright Points, and Concentration of Magnetic Flux

NASA Technical Reports Server (NTRS)

Falconer, D. A.; Moore, R. L.; Porter, J. G.; Hathaway, D. H.

1998-01-01

By combining quiet-region Fe XII coronal images from SOHO/EIT with magnetograms from NSO/Kitt Peak and from SOHO/MDI, we show that on scales larger than a supergranule the population of network coronal bright points and the magnetic flux content of the network are both markedly greater under the bright half of the quiet corona than under the dim half. These results (1) support the view that the heating of the entire corona in quiet regions and coronal holes is driven by fine-scale magnetic activity (microflares, explosive events, spicules) seated low in the magnetic network, and (2) suggest that this large-scale modulation of the magnetic flux and coronal heating is a signature of giant convection cells.

Coronal magnetic structure and the latitude and longitude distribution of energetic particles, 1-5 AU

NASA Technical Reports Server (NTRS)

Roelof, E. C.; Mitchell, D. G.

1979-01-01

The relation of the coronal magnetic field structure to the distribution of approximately 1 MeV protons in interplanetary space between 1 and 5 AU is discussed. After ordering the interplanetary data by its estimated coronal emission source location in heliographic coordinates, the multispacecraft measured proton fluxes are compared with coronal magnetic field structure infrared as observed in soft X-ray photographs and potential field calculations. Evidence for the propagation and possible acceleration of solar flare protons on high magnetic loop structure in the corona is presented. Further, it is shown that corotating proton flux enhancements are associated with regions of low coronal X-ray emission (including coronal holes), usually in association with solar wind stream structure.

Coronal disturbances and their terrestrial effects /Tutorial Lecture/

NASA Technical Reports Server (NTRS)

Rust, D. M.

1983-01-01

An assessment is undertaken of recent approaches to the prediction of the interplanetary consequences of coronal disturbances, with attention to the relationships of shocks and energetic particles to coronal transients, of proton events to gamma-ray and microwave bursts, of geomagnetic storms to filament eruptions, and of solar wind increases to the flare site magnetic field direction. A discussion is given concerning the novel phenomenon of transient coronal holes, which appear astride the long decay enhancements of 2-50 A X-ray emission following H-alpha filament eruptions. These voids in the corona are similar to long-lived coronal holes, which are the sources of high speed solar wind streams. The transient coronal holes may also be associated with transient solar wind speed increases.

Coronal magnetic fields from multiple type II bursts

NASA Astrophysics Data System (ADS)

Honnappa, Vijayakumar; Raveesha, K. H.; Subramanian, K. R.

Coronal magnetic fields from multiple type II bursts Vijayakumar H Doddamani1*, Raveesha K H2 and Subramanian3 1Bangalore University, Bangalore, Karnataka state, India 2CMR Institute of Technology, Bangalore, Karnataka state, India 3 Retd, Indian Institute of Astrophysics, Bangalore, Karnataka state, India Abstract Magnetic fields play an important role in the astrophysical processes occurring in solar corona. In the solar atmosphere, magnetic field interacts with the plasma, producing abundant eruptive activities. They are considered to be the main factors for coronal heating, particle acceleration and the formation of structures like prominences, flares and Coronal Mass Ejections. The magnetic field in solar atmosphere in the range of 1.1-3 Rsun is especially important as an interface between the photospheric magnetic field and the solar wind. Its structure and time dependent change affects space weather by modifying solar wind conditions, Cho (2000). Type II doublet bursts can be used for the estimation of the strength of the magnetic field at two different heights. Two type II bursts occur sometimes in sequence. By relating the speed of the type II radio burst to Alfven Mach Number, the Alfven speed of the shock wave generating type II radio burst can be calculated. Using the relation between the Alfven speed and the mean frequency of emission, the magnetic field strength can be determined at a particular height. We have used the relative bandwidth and drift rate properties of multiple type II radio bursts to derive magnetic field strengths at two different heights and also the gradient of the magnetic field in the outer corona. The magnetic field strength has been derived for different density factors. It varied from 1.2 to 2.5 gauss at a solar height of 1.4 Rsun. The empirical relation of the variation of the magnetic field with height is found to be of the form B(R) = In the present case the power law index ‘γ’ varied from -3 to -2 for variation of density factor from 1 to 5. Key Words: Magnetic field, photosphere, corona, solar wind, bursts *Email:drvkdmani@gmail.com

Non-thermal recombination - a neglected source of flare hard X-rays and fast electron diagnostics (Corrigendum)

NASA Astrophysics Data System (ADS)

Brown, J. C.; Mallik, P. C. V.; Badnell, N. R.

2010-06-01

Brown and Mallik (BM) recently claimed that non-thermal recombination (NTR) can be a dominant source of flare hard X-rays (HXRs) from hot coronal and chromospheric sources. However, major discrepancies between the thermal continua predicted by BM and by the Chianti database as well as RHESSI flare data, led us to discover substantial errors in the heuristic expression used by BM to extend the Kramers expressions beyond the hydrogenic case. Here we present the relevant corrected expressions and show the key modified results. We conclude that, in most cases, NTR emission was overestimated by a factor of 1-8 by BM but is typically still large enough (as much as 20-30% of the total emission) to be very important for electron spectral inference and detection of electron spectral features such as low energy cut-offs since the recombination spectra contain sharp edges. For extreme temperature regimes and/or if the Fe abundance were as high as some values claimed, NTR could even be the dominant source of flare HXRs, reducing the electron number and energy budget, problems such as in the extreme coronal HXR source cases reported by e.g. Krucker et al.

Acceleration of the Fast Solar Wind by Solitary Waves in Coronal Holes

NASA Technical Reports Server (NTRS)

Ofman, Leon

2001-01-01

The purpose of this investigation is to develop a new model for the acceleration of the fast solar wind by nonlinear. time-dependent multidimensional MHD simulations of waves in solar coronal holes. Preliminary computational studies indicate that nonlinear waves are generated in coronal holes by torsional Alfv\\'{e}n waves. These waves in addition to thermal conduction may contribute considerably to the accelerate the solar wind. Specific goals of this proposal are to investigate the generation of nonlinear solitary-like waves and their effect on solar wind acceleration by numerical 2.5D MHD simulation of coronal holes with a broad range of plasma and wave parameters; to study the effect of random disturbances at the base of a solar coronal hole on the fast solar wind acceleration with a more advanced 2.5D MHD model and to compare the results with the available observations; to extend the study to a full 3D MHD simulation of fast solar wind acceleration with a more realistic model of a coronal hole and solar boundary conditions. The ultimate goal of the three year study is to model the, fast solar wind in a coronal hole, based on realistic boundary conditions in a coronal hole near the Sun, and the coronal hole structure (i.e., density, temperature. and magnetic field geometry,) that will become available from the recently launched SOHO spacecraft.

The observation of possible reconnection events in the boundary changes of solar coronal holes

NASA Technical Reports Server (NTRS)

Kahler, S. W.; Moses, J. Daniel

1989-01-01

Coronal holes are large scale regions of magnetically open fields which are easily observed in solar soft X-ray images. The boundaries of coronal holes are separatrices between large scale regions of open and closed magnetic fields where one might expect to observe evidence of solar magnetic reconnection. Previous studies by Nolte and colleagues using Skylab X-ray images established that large scale (greater than or equal to 9 x 10(4) km) changes in coronal hole boundaries were due to coronal processes, i.e., magnetic reconnection, rather than to photospheric motions. Those studies were limited to time scales of about one day, and no conclusion could be drawn about the size and time scales of the reconnection process at hole boundaries. Sequences of appropriate Skylab X-ray images were used with a time resolution of about 90 min during times of the central meridian passages of the coronal hole labelled Coronal Hole 1 to search for hole boundary changes which can yield the spatial and temporal scales of coronal magnetic reconnection. It was found that 29 of 32 observed boundary changes could be associated with bright points. The appearance of the bright point may be the signature of reconnection between small scale and large scale magnetic fields. The observed boundary changes contributed to the quasi-rigid rotation of Coronal Hole 1.

Acceleration of the Fast Solar Wind by Solitary Waves in Coronal Holes

NASA Technical Reports Server (NTRS)

Ofman, Leon

2000-01-01

The purpose of this investigation is to develop a new model for the acceleration of the fast solar wind by nonlinear, time-dependent multidimensional MHD simulations of waves in solar coronal holes. Preliminary computational studies indicate that solitary-like waves are generated in coronal holes nonlinearly by torsional Alfven waves. These waves in addition to thermal conduction may contribute considerably to the accelerate the solar wind. Specific goals of this proposal are to investigate the generation of nonlinear solitary-like waves and their effect on solar wind acceleration by numerical 2.5D MHD simulation of coronal holes with a broad range of plasma and wave parameters; to study the effect of random disturbances at the base of a solar coronal hole on the fast solar wind acceleration with a more advanced 2.5D MHD model and to compare the results with the available observations; to extend the study to a full 3D MHD simulation of fast solar wind acceleration with a more realistic model of a coronal hole and solar boundary conditions. The ultimate goal of the three year study is to model the fast solar wind in a coronal hole, based on realistic boundary conditions in a coronal hole near the Sun, and the coronal hole structure (i.e., density, temperature, and magnetic field geometry) that will become available from the recently launched SOHO spacecraft.

The Fate of Cool Material in the Hot Corona: Solar Prominences and Coronal Rain

NASA Astrophysics Data System (ADS)

Liu, Wei; Antolin, Patrick; Sun, Xudong; Vial, Jean-Claude; Berger, Thomas

2017-08-01

As an important chain of the chromosphere-corona mass cycle, some of the million-degree hot coronal mass undergoes a radiative cooling instability and condenses into material at chromospheric or transition-region temperatures in two distinct forms - prominences and coronal rain (some of which eventually falls back to the chromosphere). A quiescent prominence usually consists of numerous long-lasting, filamentary downflow threads, while coronal rain consists of transient mass blobs falling at comparably higher speeds along well-defined paths. It remains puzzling why such material of similar temperatures exhibit contrasting morphologies and behaviors. We report recent SDO/AIA and IRIS observations that suggest different magnetic environments being responsible for such distinctions. Specifically, in a hybrid prominence-coronal rain complex structure, we found that the prominence material is formed and resides near magnetic null points that favor the radiative cooling process and provide possibly a high plasma-beta environment suitable for the existence of meandering prominence threads. As the cool material descends, it turns into coronal rain tied onto low-lying coronal loops in a likely low-beta environment. Such structures resemble to certain extent the so-called coronal spiders or cloud prominences, but the observations reported here provide critical new insights. We will discuss the broad physical implications of these observations for fundamental questions, such as coronal heating and beyond (e.g., in astrophysical and/or laboratory plasma environments).

Relationship between coronal holes and high speed streams at L1: arrival times, durations, and intensities

NASA Astrophysics Data System (ADS)

Luo, B.; Bu, X.; Liu, S.; Gong, J.

2017-12-01

Coronal holes are sources of high-speed steams (HSS) of solar wind. When coronal holes appear at mid/low latitudes on the Sun, consequential HSSs may impact Earth and cause recurrent geospace environment disturbances, such as geomagnetic storms, relativistic electron enhancements at the geosynchronous orbit, and thermosphere density enhancements. Thus, it is of interests for space weather forecasters to predict when (arrival times), how long (time durations), and how severe (intensities) HSSs may impact Earth when they notice coronal holes on the sun and are anticipating their geoeffectiveness. In this study, relationship between coronal holes and high speed streams will be statistically investigated. Several coronal hole parameters, including passage times of solar central meridian, coronal hole longitudinal widths, intensities reflected by mean brightness, are derived using Solar Dynamics Observatory (SDO)/Atmospheric Imaging Assembly (AIA) images for years 2011 to 2016. These parameters will be correlated with in-situ solar wind measurements measured at the L1 point by the ACE spacecraft, which can give some results that are useful for space weather forecaster in predicting the arrival times, durations, and intensities of coronal hole high-speed streams in about 3 days advance.

CORONAL FOURIER POWER SPECTRA: IMPLICATIONS FOR CORONAL SEISMOLOGY AND CORONAL HEATING

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ireland, J.; McAteer, R. T. J.; Inglis, A. R., E-mail: jack.ireland@nasa.gov

The dynamics of regions of the solar corona are investigated using Atmospheric Imaging Assembly 171 Å and 193 Å data. The coronal emission from the quiet Sun, coronal loop footprints, coronal moss, and from above a sunspot is studied. It is shown that the mean Fourier power spectra in these regions can be described by a power law at lower frequencies that tails to a flat spectrum at higher frequencies, plus a Gaussian-shaped contribution that varies depending on the region studied. This Fourier spectral shape is in contrast to the commonly held assumption that coronal time series are well describedmore » by the sum of a long timescale background trend plus Gaussian-distributed noise, with some specific locations also showing an oscillatory signal. The implications of the observed spectral shape on the fields of coronal seismology and the automated detection of oscillations in the corona are discussed. The power-law contribution to the shape of the Fourier power spectrum is interpreted as being due to the summation of a distribution of exponentially decaying emission events along the line of sight. This is consistent with the idea that the solar atmosphere is heated everywhere by small energy deposition events.« less

New Evidence that Magnetoconvection Drives Solar–Stellar Coronal Heating

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tiwari, Sanjiv K.; Panesar, Navdeep K.; Moore, Ronald L.

2017-07-10

How magnetic energy is injected and released in the solar corona, keeping it heated to several million degrees, remains elusive. Coronal heating generally increases with increasing magnetic field strength. From a comparison of a nonlinear force-free model of the three-dimensional active region coronal field to observed extreme-ultraviolet loops, we find that (1) umbra-to-umbra coronal loops, despite being rooted in the strongest magnetic flux, are invisible, and (2) the brightest loops have one foot in an umbra or penumbra and the other foot in another sunspot’s penumbra or in unipolar or mixed-polarity plage. The invisibility of umbra-to-umbra loops is new evidencemore » that magnetoconvection drives solar-stellar coronal heating: evidently, the strong umbral field at both ends quenches the magnetoconvection and hence the heating. Broadly, our results indicate that depending on the field strength in both feet, the photospheric feet of a coronal loop on any convective star can either engender or quench coronal heating in the loop’s body.« less

Diagnostics of Coronal Magnetic Fields Through the Hanle Effect in UV and IR Lines

NASA Astrophysics Data System (ADS)

Raouafi, Nour E.; Riley, Pete; Gibson, Sarah; Fineschi, Silvano; Solanki, Sami K.

2016-06-01

The plasma thermodynamics in the solar upper atmosphere, particularly in the corona, are dominated by the magnetic field, which controls the flow and dissipation of energy. The relative lack of knowledge of the coronal vector magnetic field is a major handicap for progress in coronal physics. This makes the development of measurement methods of coronal magnetic fields a high priority in solar physics. The Hanle effect in the UV and IR spectral lines is a largely unexplored diagnostic. We use magnetohydrodynamic (MHD) simulations to study the magnitude of the signal to be expected for typical coronal magnetic fields for selected spectral lines in the UV and IR wavelength ranges, namely the HI Ly-α and the He I 10830 Å lines. We show that the selected lines are useful for reliable diagnosis of coronal magnetic fields. The results show that the combination of polarization measurements of spectral lines with different sensitivities to the Hanle effect may be most appropriate for deducing coronal magnetic properties from future observations.

Dynamic simulation of coronal mass ejections

NASA Technical Reports Server (NTRS)

Steinolfson, R. S.; Wu, S. T.

1980-01-01

A model is developed for the formation and propagation through the lower corona of the loop-like coronal transients in which mass is ejected from near the solar surface to the outer corona. It is assumed that the initial state for the transient is a coronal streamer. The initial state for the streamer is a polytropic, hydrodynamic solution to the steady-state radial equation of motion coupled with a force-free dipole magnetic field. The numerical solution of the complete time-dependent equations then gradually approaches a stationary coronal streamer configuration. The streamer configuration becomes the initial state for the coronal transient. The streamer and transient simulations are performed completely independent of each other. The transient is created by a sudden increase in the pressure at the base of the closed-field region in the streamer configuration. Both coronal streamers and coronal transients are calculated for values of the plasma beta (the ratio of thermal to magnetic pressure) varying from 0.1 to 100.

The Coronal Monsoon: Thermal Nonequilibrium Revealed by Periodic Coronal Rain

NASA Astrophysics Data System (ADS)

Auchère, Frédéric; Froment, Clara; Soubrié, Elie; Antolin, Patrick; Oliver, Ramon; Pelouze, Gabriel

2018-02-01

We report on the discovery of periodic coronal rain in an off-limb sequence of Solar Dynamics Observatory/Atmospheric Imaging Assembly images. The showers are co-spatial and in phase with periodic (6.6 hr) intensity pulsations of coronal loops of the sort described by Auchère et al. and Froment et al. These new observations make possible a unified description of both phenomena. Coronal rain and periodic intensity pulsations of loops are two manifestations of the same physical process: evaporation/condensation cycles resulting from a state of thermal nonequilibrium. The fluctuations around coronal temperatures produce the intensity pulsations of loops, and rain falls along their legs if thermal runaway cools the periodic condensations down and below transition-region temperatures. This scenario is in line with the predictions of numerical models of quasi-steadily and footpoint heated loops. The presence of coronal rain—albeit non-periodic—in several other structures within the studied field of view implies that this type of heating is at play on a large scale.

Changes of the boot-shaped coronal hole boundary during Whole Sun Month near sunspot minimum

NASA Astrophysics Data System (ADS)

Zhao, X. P.; Hoeksema, J. T.; Scherrer, P. H.

1999-05-01

The August 27, 1996, boot-shaped coronal hole is shown to rotate nearly rigidly at a rate of 13.25°/day, greater than the equatorial rotation rate of bipolar magnetic regions such as active regions and plages. The day-to-day variation of the coronal hole border is determined by comparing the rigid rotation projection of the disk-center hole boundary to coronal hole boundaries observed in successive daily coronal images. To determine the influence of the changing photospheric field on the location of the coronal hole boundary, a better approximation of the instantaneous global magnetic field distribution is developed and used as input to a potential-field source-surface model to compute the foot-point areas of open field lines. Day-to-day variations of the coronal hole boundary may be caused by changes of the magnetic field and plasma properties in the corona, as well as by the changing photospheric field.

Multidimensional Modeling of Coronal Rain Dynamics

NASA Astrophysics Data System (ADS)

Fang, X.; Xia, C.; Keppens, R.

2013-07-01

We present the first multidimensional, magnetohydrodynamic simulations that capture the initial formation and long-term sustainment of the enigmatic coronal rain phenomenon. We demonstrate how thermal instability can induce a spectacular display of in situ forming blob-like condensations which then start their intimate ballet on top of initially linear force-free arcades. Our magnetic arcades host a chromospheric, transition region, and coronal plasma. Following coronal rain dynamics for over 80 minutes of physical time, we collect enough statistics to quantify blob widths, lengths, velocity distributions, and other characteristics which directly match modern observational knowledge. Our virtual coronal rain displays the deformation of blobs into V-shaped features, interactions of blobs due to mostly pressure-mediated levitations, and gives the first views of blobs that evaporate in situ or are siphoned over the apex of the background arcade. Our simulations pave the way for systematic surveys of coronal rain showers in true multidimensional settings to connect parameterized heating prescriptions with rain statistics, ultimately allowing us to quantify the coronal heating input.

Surgery: Modified Pi with Triple-Bonnet Flap and Fronto-Orbital Advancement.

PubMed

Singh Raswan, Uday; Singh Chhiber, Sarbjit; Ramzan, Altaf Umar

2017-01-01

Craniosynostosis is the premature fusion of one or more of the cranial sutures and can occur as part of a syndrome or as an isolated defect. Pansynostosis is a rare form of craniosynostosis that involves premature fusion of all the cranial sutures (coronal, sagittal, metopic, and occipital). Particularly in cases of late presentation, there are heightened clinical concerns, both functional and aesthetic. In untreated cases of pansynostosis and increased intracranial pressure, optic nerve damage progresses to optic atrophy and then blindness. Cranial vault reconstruction is the standard surgical treatment. We attempt to highlight the importance of modifying the osteotomies and reshaping of the cranial vault based on individual requirements in order to achieve the best possible result and to prevent catastrophic blood loss. We present a case of modified pi with triple-bonnet flap and fronto-orbital advancement, an individual modification of the techniques of cranial vault reconstruction, in a patient with pansynostosis with optic atrophy. The technical variation can be applied to any case of pansynostosis requiring cranial vault reconstruction. © 2017 S. Karger AG, Basel.

[Surface stress analysis of distal extension removable partial denture retained with two types of semi-precision attachments].

PubMed

Wang, Y; Mi, N; Qing, F; Liu, F; Chen, J

2001-10-01

The aims of this study are to analyze the surface stress of the periodontal supporting bone of the bilateral distol extension removable partial denture which is retained by using intra-coronal or extra-coronal semi-precision attachment, and to characterize the biomechanics of these two designs by using a strain gauge. A fresh human mandible specimen with 76|67 missing and six bilateral partial removable denture retained with six semi-precision attachments were made, including three attachments with intra-coronal studs and three attachments with extra-coronal vertical bars. A total of six 45 degrees rosette strain gauges were bonded at six prepared points on the surface of the mandible to measure the surface stress, including the middle point between 76 of the buccal edentulous alveolar crest area under the denture base verge(point 1), the distal buccal cervix of 5 (point 2), the buccal apical area of 5 (point 3), the buccal middle area of 34 roots (point 4, 5), the lingual middle area of 5 root (point 6). The static loads of 14N, 28N and 42N were applied vertically, buccally 45 degrees, lingually 45 degrees at the middle point of the 6|6 occlusal surface. The micro-strain was recorded, and the maximal/minimal principle stresses were calculated for each RPD and each point. The stress characteristics of these two types of attachments were compared and analyzed. In most situations, the stress of these two semi-precision attachments showed significant differences. The vertical load: The stress values of these intra-coronal and extra-coronal attachments at points 1, 2, 3, 4, 6 differed significantly(P < 0.05), including points 1, 2, (sigma intra < sigma extra) and points 3, 4, 6(sigma intra > sigma extra). Buccal loads: The stress values of these intra-coronal and extra-coronal attachments at points 1, 2, 3, 4, 5 differed significantly(P < 0.05), including points 1, 2(sigma intra < sigma extra) and points 3, 4, 5(sigma intra > sigma extra). Lingual loads: The stress values of these intra-coronal and extra-coronal attachments at points 2, 3, 4, 6 differed significantly (P < 0.05, sigma intra > sigma extra). The intra-coronal attachment generally produced higher stress at the site of the alveolar bone around the abutment than the extra-coronal attachment, but extra-coronal attachment produced higher stress at the edentulous alveolar crest and the distal cervical alveolar bone of the distal abutment than the intra-coronal attachment. The intra-coronal attachment is suggested to be applied in some cases that the periodontal condition of distal abutment was good, and the extra-coronal attachment is suggested to be used in some cases that the condition of the edentulous alveolar crest is fairly good, while the periodontal condition of the distal abutment was relatively weak.

Determination of coronal magnetic fields from vector magnetograms

NASA Technical Reports Server (NTRS)

Mikic, Zoran

1992-01-01

The determination of coronal magnetic fields from vector magnetograms, including the development and application of algorithms to determine force-free coronal fields above selected observations of active regions is studied. Two additional active regions were selected and analyzed. The restriction of periodicity in the 3-D code which is used to determine the coronal field was removed giving the new code variable mesh spacing and is thus able to provide a more realistic description of coronal fields. The NOAA active region AR5747 of 20 Oct. 1989 was studied. A brief account of progress during the research performed is reported.

Constraints on active region coronal heating properties from observations and modeling of chromospheric, transition region, and coronal emission

NASA Astrophysics Data System (ADS)

Testa, P.; Polito, V.; De Pontieu, B.; Carlsson, M.; Reale, F.; Allred, J. C.; Hansteen, V. H.

2017-12-01

We investigate coronal heating properties in active region cores in non-flaring conditions, using high spatial, spectral, and temporal resolution chromospheric/transition region/coronal observations coupled with detailed modeling. We will focus, in particular, on observations with the Interface Region Imaging Spectrograph (IRIS), joint with observations with Hinode (XRT and EIS) and SDO/AIA. We will discuss how these observations and models (1D HD and 3D MHD, with the RADYN and Bifrost codes) provide useful diagnostics of the coronal heating processes and mechanisms of energy transport.

The association of Aedes aegypti and Ae. albopictus in Allende, Nuevo León, Mexico.

PubMed

Mercado-Hernandez, Roberto; Aguilar-Gueta, Juan de Dios; Fernandez-Salas, Ildefoso; Earl, Paul R

2006-03-01

The recent appearance of Aedes Stegomyia albopictus (Skuse) in Nuevo León (NL) worries health officials. It is a vector of dengue fever in Asia and is more resistant to lower temperatures than Ae. aegypti. The objective of this study was to learn about some ecological parameters of Ae. albopictus and their association with Ae. aegypti, and other culicids in Allende, NL, Mexico, during 1999. Allende is a small town close to metropolitan Monterrey, which has 4 million inhabitants. The design was random with monthly sampling of 175 ovitraps. Chi-square analyses were performed with data of presence, absence, frequency, and relative abundances. During the study, the species Culex tarsalis (Coquillet), Cx. thriambus (Dyar), Cx. pipiens (Linnaeus), Cx. coronator (Dyar and Knab), Ae. albopictus, Ae. aegypti, Toxorhynchites rutilus (Coquillet), and Ae. triseriatus (Say) were found. April is the month for large numbers of mosquito species. September had the highest populations in positive ovitraps (66.67%), followed by July (63.27% of traps). Aedes aegypti was the most abundant (65.13%), followed by Ae. albopictus (19.71%). Both Ae. albopictus and Ae. aegypti were found from April until December. Aedes aegypti was more abundant than Ae. albopictus, except in August, when they were similar (chi2 = 0.197, P < 0.05). We found significant association between the presence of both species for every study month (chi2 = 9.837, P < 0.05), with a contingency coefficient of 0.247. September and November were the months having the most mosquitoes in this association. Only considering Ae. albopictus, more were found in ovitraps in July (34.6%), followed by September (33.3%). However, its presence was not significant throughout the year. Of 2 zones, in town and at the river, prevalence indicated that Ae. albopictus preferred the river. This mosquito is in its establishment phase in this area and requires further studies.

Evaluation of time required for recontamination of coronally sealed canals medicated with calcium hydroxide and chlorhexidine.

PubMed

Gomes, B P F A; Sato, E; Ferraz, C C R; Teixeira, F B; Zaia, A A; Souza-Filho, F J

2003-09-01

To determine in vitro the time required for recontamination of coronally sealed canals medicated with either calcium hydroxide (CaOH2), 2% chlorhexidine gel (CG) or with a combination of both. Eighty intact, caries-free, premolar teeth with straight roots and mature apices were selected for the study. After biomechanical preparation of 75 teeth, they were randomly divided into nine groups according to the intracanal medicament and the coronal seal with 'Intermediate Restorative Material' (IRM) as follows: (i) 10 teeth medicated with CG, coronally unsealed; (ii) 10 teeth medicated with CaOH2, coronally unsealed; (iii) 10 teeth medicated with CaOH2 + CG, coronally unsealed; (iv) 10 teeth medicated with CG + coronal seal; (v) 10 teeth medicated with CaOH2 + coronal seal; (vi) 10 teeth medicated with CG + CaOH2 + coronal seal; (vii) 10 teeth without intracanal medicament and coronally sealed; (viii) 5 teeth without intracanal medicament and coronally unsealed, used as the positive control group (PC); (ix) 5 teeth with intact crowns used as the negative control group (NC). Glass flasks were filled with Brain Heart Infusion broth (BHI), so that only the root apex was in contact with the broth, while the crown was immersed in human saliva + BHI (3:1). The flasks were then incubated at 37 degrees C in an atmosphere of 10% CO2, and microbial growth was checked daily. All specimens of the PC showed contamination within 1 day of incubation, while the NC showed no evidence of broth turbidity. Recontamination was detected after an average time of 3.7 days in the unsealed canals medicated with CG, 1.8 days in the group medicated with CaOH2 and 2.6 days in the group medicated with CaOH2 + CG. When the crowns were sealed with IRM, recontamination was detected within 13.5 days in the canals medicated with CG, after 17.2 days in the group medicated with CaOH2 and after 11.9 days in the group medicated with CG + CaOH2. The group with no medication, but sealed with IRM, showed recontamination after 8.7 days. There were statistically significant differences between the teeth with or without coronal seal (P<0.05). The coronal seal delayed but did not prevent leakage of microorganisms. There was no difference between the various medicaments.

Endoscopically assisted intraoral modified Le Fort II type midfacial advancement using piezoelectric surgery and an intraoperative RED system.

PubMed

Hara, Shingo; Mitsugi, Masaharu; Kanno, Takahiro; Nomachi, Akihiko; Kawakami, Seiichi; Tatemoto, Yukihiro

2013-02-01

The Le Fort II midfacial advancement appears to be an effective surgical method for the treatment of severe midfacial-nose hypoplasia with a skeletal class III malocclusion, which is usually combined with syndromic midfacial anomalies. However, the conventional surgical method requires the coronal approach, including a coronal incision, together with other surgical approaches, such as an intraoral incision. Therefore, surgeons often hesitate to propose this type of osteotomy, even for patients who develop severe nonsyndromic midfacial-nose hypoplasia. This report presents a new surgical approach for performing a safe Le Fort II osteotomy for nasomaxillary, midfacial corrective advancement via a solely intraoral approach. Surgery was performed with endoscopically assisted piezoelectric surgery. The osteotomized nasomaxillary Le Fort II segment was successfully protracted without aggressive down-fracture procedures with the sole intraoperative use of a rigid external distraction (RED) system, followed by internal rigid fixation, and the subsequent removal of the RED system. Seven patients (all patients were nonsyndromic, but 2 had cleft lip and palate, and an average age of 19.9 years) were included in this study. The degrees of midfacial advancement at the base of nasal bone (the top edge of the modified Le Fort II segment) that was osteotomized and at maxillary point A was 8.3 mm (range 5.8 mm to 10.5mm) and 8.5 mm (range 5.9 mm to 9.8 mm), respectively. This new method less invasively facilitates safe, secure, and ideal nasomaxillary midfacial protraction to yield a satisfactory resultant facial profile and favorable occlusion in patients with severe midfacial-nose hypoplasia and skeletal class III malocclusions. Copyright © 2013 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.

Magnetohydrodynamic Simulation of a Streamer Beside a Realistic Coronal Hole

NASA Technical Reports Server (NTRS)

Suess, S. T.; Wu, S. T.; Wang, A. H.; Poletto, G.

1994-01-01

Existing models of coronal streamers establish their credibility and act as the initial state for transients. The models have produced satisfactory streamer simulations, but unsatisfactory coronal hole simulations. This is a consequence of the character of the models and the boundary conditions. The models all have higher densities in the magnetically open regions than occur in coronal holes (Noci, et al., 1993).

“Coming to Town”: The Impact of Urbanicity, Cigarette Advertising, and Network Norms on the Smoking Attitudes of Black Women in Cape Town, South Africa

PubMed Central

Williams, Chyvette T.; Marks, Amy Seidel

2008-01-01

This study was conducted to examine the effect of urban living on smoking attitudes among black African women in South Africa. We examine how urbanicity affects attitudes toward smoking and how it moderates the relationship between both advertising exposure and network norms on black women’s smoking attitudes. Respondents were 975 black women currently living in Cape Town townships, some of which were raised in rural villages or small towns. Respondents completed a cross-sectional survey, which included data on smoking attitudes, norms, and exposure to cigarette advertising. Multiple linear regression analysis was performed with smoking attitudes as the response variable, and urbanicity, cigarette advertising exposure, and network smoking norms as primary explanatory variables. Interactions were tested to determine whether urbanicity modified the effect of advertising exposure and network norms on smoking attitudes. Independent effects of urbanicity, exposure to cigarette advertising, and greater smoking prevalence within women’s networks were associated with more favorable smoking attitudes. In addition, urbanicity moderated the relationship between network smoking norms and smoking attitudes, but not cigarette advertising exposure and smoking attitudes. Urbanicity, cigarette advertising, and networks play important roles in women’s attitudes toward smoking, and potentially, smoking behavior. Overall, our results suggest that strong and creative anti-smoking efforts are needed to combat the potential for a smoking epidemic among an increasingly urbanized population of black women in South Africa and similar emerging markets. Additional research is warranted. PMID:18563573

Longitudinal changes in the intake of energy and macronutrients of elderly Europeans. SENECA Investigators.

PubMed

Moreiras, O; van Staveren, W A; Amorim Cruz, J A; Carbajal, A; de Henauw, S; Grunenberger, F; Roszkowski, W

1996-07-01

To assess longitudinal changes in intakes of energy and macronutrients in elderly Europeans. Longitudinal study including a dietary assessment in 1988/1989, which was repeated in 1993. Serial data were collected in nine European towns: Belgium: Hamme (H/B); Denmark: Roskilde (R/DK); France: Haguenau (H/F) and Romans (R/F); Italy: Padua (P/I); the Netherlands: Culemborg (C/NL); Portugal: Vila Franca de Xira (V/P); Spain: Betanzos (B/E) and Switzerland: Yverdon (Y/CH). In other centres dietary intake data were collected in 1993 only: Portugal: Coimbra (C/P); Poland: Marki (M/PL); Northern Ireland: Ballymoney-Limavady-Portstewart (BLP/NI/UK) and United States: Mansfield (Connecticut) (M/CT/USA). Using standardized methodologies, data were collected from a random stratified sample of elderly men and women born between 1913 and 1918. In 1993 dietary intake data were collected from 1125 subjects by a modified validated dietary history method. Over the 4-year study period, a decline in mean energy intake of one MJ or less per day was observed in most towns, which was significant (P < 0.01) in only four of the towns. The within- and between-centre variation of change was large. Overall, a slight decline was reported for all macronutrients and with the exception of protein, large within and between centre variations were observed in both men and women. Intake of energy and macronutrients was found to decline with age. This may be of special concern for small eaters.

Coronal Heating and the Magnetic Flux Content of the Network

NASA Technical Reports Server (NTRS)

Falconer, D. A.; Moore, R. L.; Porter, J. G.; Hathaway, D. H.; Rose, M. Franklin (Technical Monitor)

2001-01-01

Previously, from analysis of SOHO coronal images in combination with Kitt Peak magnetograms, we found that the quiet corona is the sum of two components: the large-scale corona and the coronal network. The large-scale corona consists of all coronal-temperature (T approximately 10(exp 6) K) structures larger than supergranules (greater than approximately 30,000 kilometers). The coronal network (1) consists of all coronal-temperature structures smaller than supergranules, (2) is rooted in and loosely traces the photospheric magnetic network, (3) has its brightest features seated on polarity dividing lines (neutral lines) in the network magnetic flux, and (4) produces only about 5% of the total coronal emission in quiet regions. The heating of the coronal network is apparently magnetic in origin. Here, from analysis of EIT coronal images of quiet regions in combination with magnetograms of the same quiet regions from SOHO/MDI and from Kitt Peak, we examine the other 95% of the quiet corona and its relation to the underlying magnetic network. We find: (1) Dividing the large-scale corona into its bright and dim halves divides the area into bright "continents" and dark "oceans" having spans of 2-4 supergranules. (2) These patterns are also present in the photospheric magnetograms: the network is stronger under the bright half and weaker under the dim half. (3) The radiation from the large-scale corona increases roughly as the cube root of the magnetic flux content of the underlying magnetic network. In contrast, the coronal radiation from an active region increases roughly linearly with the magnetic flux content of the active region. We assume, as is widely held, that nearly all of the large-scale corona is magnetically rooted in the network. Our results suggest that either the coronal heating in quiet regions has a large non-magnetic component, or, if the heating is predominantly produced via the magnetic field, the mechanism is significantly different than in active regions.

Elongated Coronal Hole

NASA Image and Video Library

2016-03-24

NASA Solar Dynamics Observatory shows a long coronal hole has rotated so that was temporarily facing right towards Earth Mar. 23-25, 2016. Coronal holes appear dark when viewed in some wavelengths of extreme ultraviolet light.

77 FR 21791 - Proposed Flood Hazard Determinations

Federal Register 2010, 2011, 2012, 2013, 2014

2012-04-11

... Town Hall, 2 Renshaw Road, Darien, CT 06820. Town of Fairfield John J. Sullivan Independence Hall, 725 Old Post Road, Fairfield, CT 06824. Town of Greenwich Town Hall, 101 Field Point Road, Greenwich, CT... at: http://www.rampp-team.com/md.htm Town of Accident Town Hall, 104 South North Street, Accident, MD...

DOE Office of Scientific and Technical Information (OSTI.GOV)

Antolin, P.; Verwichte, E., E-mail: patrick.antolin@astro.uio.no, E-mail: erwin.verwichte@warwick.ac.uk

The condensations composing coronal rain, falling down along loop-like structures observed in cool chromospheric lines such as H{alpha} and Ca II H, have long been a spectacular phenomenon of the solar corona. However, considered a peculiar sporadic phenomenon, it has not received much attention. This picture is rapidly changing due to recent high-resolution observations with instruments such as the Hinode/Solar Optical Telescope (SOT), CRISP of the Swedish 1-m Solar Telescope, and the Solar Dynamics Observatory. Furthermore, numerical simulations have shown that coronal rain is the loss of thermal equilibrium of loops linked to footpoint heating. This result has highlighted themore » importance that coronal rain can play in the field of coronal heating. In this work, we further stress the importance of coronal rain by showing the role it can play in the understanding of the coronal magnetic field topology. We analyze Hinode/SOT observations in the Ca II H line of a loop in which coronal rain puts in evidence in-phase transverse oscillations of multiple strand-like structures. The periods, amplitudes, transverse velocities, and phase velocities are calculated, allowing an estimation of the energy flux of the wave and the coronal magnetic field inside the loop through means of coronal seismology. We discuss the possible interpretations of the wave as either standing or propagating torsional Alfven or fast kink waves. An estimate of the plasma beta parameter of the condensations indicates a condition that may allow the often observed separation and elongation processes of the condensations. We also show that the wave pressure from the transverse wave can be responsible for the observed low downward acceleration of coronal rain.« less

DIRECT OBSERVATION OF SOLAR CORONAL MAGNETIC FIELDS BY VECTOR TOMOGRAPHY OF THE CORONAL EMISSION LINE POLARIZATIONS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kramar, M.; Lin, H.; Tomczyk, S., E-mail: kramar@cua.edu, E-mail: lin@ifa.hawaii.edu, E-mail: tomczyk@ucar.edu

We present the first direct “observation” of the global-scale, 3D coronal magnetic fields of Carrington Rotation (CR) Cycle 2112 using vector tomographic inversion techniques. The vector tomographic inversion uses measurements of the Fe xiii 10747 Å Hanle effect polarization signals by the Coronal Multichannel Polarimeter (CoMP) and 3D coronal density and temperature derived from scalar tomographic inversion of Solar Terrestrial Relations Observatory (STEREO)/Extreme Ultraviolet Imager (EUVI) coronal emission lines (CELs) intensity images as inputs to derive a coronal magnetic field model that best reproduces the observed polarization signals. While independent verifications of the vector tomography results cannot be performed, wemore » compared the tomography inverted coronal magnetic fields with those constructed by magnetohydrodynamic (MHD) simulations based on observed photospheric magnetic fields of CR 2112 and 2113. We found that the MHD model for CR 2112 is qualitatively consistent with the tomography inverted result for most of the reconstruction domain except for several regions. Particularly, for one of the most noticeable regions, we found that the MHD simulation for CR 2113 predicted a model that more closely resembles the vector tomography inverted magnetic fields. In another case, our tomographic reconstruction predicted an open magnetic field at a region where a coronal hole can be seen directly from a STEREO-B/EUVI image. We discuss the utilities and limitations of the tomographic inversion technique, and present ideas for future developments.« less

76 FR 50443 - Proposed Flood Elevation Determinations

Federal Register 2010, 2011, 2012, 2013, 2014

2011-08-15

... the of Hull, Town of intersection of Brant Marion, Town of Beach Avenue and Ocean Mattapoisett, Town..., MA 02043. Town of Hull Maps are available for inspection at the Town Hall, 253 Atlantic Avenue, Hull...

Radio Studies of Coronal Holes.

DTIC Science & Technology

1981-03-01

Withbroe (1978) has pointed out, "The transport of energy by thermal conduction into the transition zone is a primary coronal cooling mechanism." Thus, the...temperature and particle density gradients in the transition zone are of critical importance in understanding the energy balance of a coronal hole. The...coronal hole has been provided by Konp and Orrall (1977), but a quantitative understanding requires a detailed knowledge of the energy balance in the

Identifying open magnetic field regions of the Sun and their heliospheric counterparts

NASA Astrophysics Data System (ADS)

Krista, L. D.; Reinard, A.

2017-12-01

Open magnetic regions on the Sun are either long-lived (coronal holes) or transient (dimmings) in nature. Both phenomena are fundamental to our understanding of the solar behavior as a whole. Coronal holes are the sources of high-speed solar wind streams that cause recurrent geomagnetic storms. Furthermore, the variation of coronal hole properties (area, location, magnetic field strength) over the solar activity cycle is an important marker of the global evolution of the solar magnetic field. Dimming regions, on the other hand, are short-lived coronal holes that often emerge in the wake of solar eruptions. By analyzing their physical properties and their temporal evolution, we aim to understand their connection with their eruptive counterparts (flares and coronal mass ejections) and predict the possibility of a geomagnetic storm. The author developed the Coronal Hole Automated Recognition and Monitoring (CHARM) and the Coronal Dimming Tracker (CoDiT) algorithms. These tools not only identify but track the evolution of open magnetic field regions. CHARM also provides daily coronal hole maps, that are used for forecasts at the NOAA Space Weather Prediction Center. Our goal is to better understand the processes that give rise to eruptive and non-eruptive open field regions and investigate how these regions evolve over time and influence space weather.

Origin of Pre-Coronal-Jet Minifilaments: Flux Cancellation

NASA Technical Reports Server (NTRS)

Panesar, Navdeep K.; Sterling, Alphonse; Moore, Ronald L.

2017-01-01

Coronal jets are frequent magnetically channeled narrow eruptions. All coronal jets observed in EUV and X-ray images show a bright spire with a base brightening, also known as jet bright point (JBP). Recent studies of jets show that coronal jets are driven by small-scale filament eruptions (e.g. Hong et al. 2011, Shen et al. 2012, Adams et al. 2014, Sterling et al. 2015). We recently investigated the triggering mechanism of ten on-disk quiet-region coronal jet eruptions and found that magnetic flux cancellation at the neutral line of minifilaments is the main cause of quiet-region jet eruptions (Panesar et al.2016).

The evolution of active region loop plasma

NASA Technical Reports Server (NTRS)

Krall, K. R.; Antiochos, S. K.

1980-01-01

The adjustment of coronal active-region loops to changes in their heating rate is investigated numerically. The one-dimensional hydrodynamic equations are solved subject to boundary conditions in which heat flux-induced mass exchange between coronal and chromospheric components is allowed. The calculated evolution of physical parameters suggests that (1) mass supplied during chromospheric evaporation is much more effective in moderating coronal temperature excursions than when downward heat flux is dissipated by a static chromosphere, and (2) the method by which the chromosphere responds to changing coronal conditions can significantly influence coronal readjustment time scales. Observations are cited which illustrate the range of possible fluctuations in the heating rates.

Coronal Hole Front and Center

NASA Image and Video Library

2016-05-18

A substantial coronal hole had rotated so that it temporarily faced right towards Earth May, 17-19, 2016. This coronal hole area is the dark area at the top center of this image from NASA Solar Dynamics Observatory.

EFFECT OF CORONAL TEMPERATURE ON THE SCALE OF SOLAR CHROMOSPHERIC JETS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Iijima; Yokoyama, T.H., E-mail: h.iijima@eps.s.u-tokyo.ac.jp

2015-10-20

We investigate the effect of coronal temperature on the formation process of solar chromospheric jets using two-dimensional magnetohydrodynamic simulations of the region from the upper convection zone to the lower corona. We develop a new radiative magnetohydrodynamic code for the dynamic modeling of the solar atmosphere, employing an LTE equation of state, optically thick radiative loss in the photosphere, optically thin radiative loss in the chromosphere and the corona, and thermal conduction along the magnetic field lines. Many chromospheric jets are produced in the simulations by shock waves passing through the transition region. We find that these jets are projectedmore » farther outward when the coronal temperature is lower (similar to that in coronal holes) and shorter when the coronal temperature is higher (similar to that in active regions). When the coronal temperature is high, the deceleration of the chromospheric jets is consistent with the model in which deceleration is determined by the periodic chromospheric shock waves. However, when the coronal temperature is low, the gravitational deceleration becomes more important and the chromospheric jets approach ballistic motion.« less

Infrared coronal emission lines and the possibility of their laser emission in Seyfert nuclei

NASA Technical Reports Server (NTRS)

Greenhouse, Matthew A.; Feldman, Uri; Smith, Howard A.; Klapisch, Marcel; Bhatia, Anand K.; Bar-Shalom, Avi

1993-01-01

Results are presented from detailed balance calculations, and a compilation of atomic data and other model calculations designed to support upcoming ISO and current observing programs involving IR coronal emission lines, together with a table with a complete line list of infrared transitions within the ground configurations 2s2 2p(k), 3s2 3p(k), and the first excited configurations 2s 2p and 3s 3p of highly ionized astrophysically abundant elements. The temperature and density parameter space for dominant cooling via IR coronal lines is presented, and the relationship of IR and optical coronal lines is discussed. It is found that, under physical conditions found in Seyfert nuclei, 14 of 70 transitions examined have significant population inversions in levels that give rise to IR coronal lines. Several IR coronal line transitions were found to have laser gain lengths that correspond to column densities of 10 exp 24-25/sq cm which are modeled to exist in Seyfert nuclei. Observations that can reveal inverted level populations and laser gain in IR coronal lines are suggested.

High-dose vitamin D3 reduces deficiency caused by low UVB exposure and limits HIV-1 replication in urban Southern Africans

PubMed Central

Coussens, Anna K.; Naude, Celeste E.; Goliath, Rene; Chaplin, George; Wilkinson, Robert J.; Jablonski, Nina G.

2015-01-01

Cape Town, South Africa, has a seasonal pattern of UVB radiation and a predominantly dark-skinned urban population who suffer high HIV-1 prevalence. This coexistent environmental and phenotypic scenario puts residents at risk for vitamin D deficiency, which may potentiate HIV-1 disease progression. We conducted a longitudinal study in two ethnically distinct groups of healthy young adults in Cape Town, supplemented with vitamin D3 in winter, to determine whether vitamin D status modifies the response to HIV-1 infection and to identify the major determinants of vitamin D status (UVB exposure, diet, pigmentation, and genetics). Vitamin D deficiency was observed in the majority of subjects in winter and in a proportion of individuals in summer, was highly correlated with UVB exposure, and was associated with greater HIV-1 replication in peripheral blood cells. High-dosage oral vitamin D3 supplementation attenuated HIV-1 replication, increased circulating leukocytes, and reversed winter-associated anemia. Vitamin D3 therefore presents as a low-cost supplementation to improve HIV-associated immunity. PMID:26080414

High-dose vitamin D3 reduces deficiency caused by low UVB exposure and limits HIV-1 replication in urban Southern Africans

NASA Astrophysics Data System (ADS)

Coussens, Anna K.; Naude, Celeste E.; Goliath, Rene; Chaplin, George; Wilkinson, Robert J.; Jablonski, Nina G.

2015-06-01

Cape Town, South Africa, has a seasonal pattern of UVB radiation and a predominantly dark-skinned urban population who suffer high HIV-1 prevalence. This coexistent environmental and phenotypic scenario puts residents at risk for vitamin D deficiency, which may potentiate HIV-1 disease progression. We conducted a longitudinal study in two ethnically distinct groups of healthy young adults in Cape Town, supplemented with vitamin D3 in winter, to determine whether vitamin D status modifies the response to HIV-1 infection and to identify the major determinants of vitamin D status (UVB exposure, diet, pigmentation, and genetics). Vitamin D deficiency was observed in the majority of subjects in winter and in a proportion of individuals in summer, was highly correlated with UVB exposure, and was associated with greater HIV-1 replication in peripheral blood cells. High-dosage oral vitamin D3 supplementation attenuated HIV-1 replication, increased circulating leukocytes, and reversed winter-associated anemia. Vitamin D3 therefore presents as a low-cost supplementation to improve HIV-associated immunity.

The psychological well-being of children orphaned by AIDS in Cape Town, South Africa.

PubMed

Cluver, Lucie; Gardner, Frances

2006-07-19

An estimated 2 million children are parentally bereaved by AIDS in South Africa. Little is known about mental health outcomes for this group. This study aimed to investigate mental health outcomes for urban children living in deprived settlements in Cape Town. 30 orphaned children and 30 matched controls were compared using standardised questionnaires (SDQ) on emotional and behavioural problems, peer and attention difficulties, and prosocial behaviour. The orphan group completed a modified version of a standardised questionnaire (IES-8), measuring Post-Traumatic Stress symptoms. Group differences were tested using t-tests and Pearson's chi-square. Both groups scored highly for peer problems, emotional problems and total scores. However, orphans were more likely to view themselves as having no good friends (p = .002), to have marked concentration difficulties (p = .03), and to report frequent somatic symptoms (p = .05), but were less likely to display anger through loss of temper (p = .03). Orphans were more likely to have constant nightmares (p = .01), and 73% scored above the cut-off for Post-Traumatic Stress Disorder. Findings suggest important areas for larger-scale research for parentally-bereaved children.

Determination of coronal magnetic fields from vector magnetograms

NASA Technical Reports Server (NTRS)

Mikic, Zoran

1993-01-01

This report covers technical progress during the second year of the contract entitled 'Determination of Coronal Magnetic Fields from Vector Magnetograms,' NASW-4728, between NASA and Science Applications International Corporation, and covers the period January 1, 1993 to December 31, 1993. Under this contract SAIC has conducted research into the determination of coronal magnetic fields from vector magnetograms, including the development and application of algorithms to determine force-free coronal fields above selected observations of active regions. The contract began on June 30, 1992 and has a completion date of December 31, 1994. This contract is a continuation of work started in a previous contract, NASW-4571, which covered the period November 15, 1990 to December 14, 1991. During this second year we have concentrated on studying additional active regions and in using the estimated coronal magnetic fields to compare to coronal features inferred from observations.

Key aspects of coronal heating

PubMed Central

Klimchuk, James A.

2015-01-01

We highlight 10 key aspects of coronal heating that must be understood before we can consider the problem to be solved. (1) All coronal heating is impulsive. (2) The details of coronal heating matter. (3) The corona is filled with elemental magnetic stands. (4) The corona is densely populated with current sheets. (5) The strands must reconnect to prevent an infinite build-up of stress. (6) Nanoflares repeat with different frequencies. (7) What is the characteristic magnitude of energy release? (8) What causes the collective behaviour responsible for loops? (9) What are the onset conditions for energy release? (10) Chromospheric nanoflares are not a primary source of coronal plasma. Significant progress in solving the coronal heating problem will require coordination of approaches: observational studies, field-aligned hydrodynamic simulations, large-scale and localized three-dimensional magnetohydrodynamic simulations, and possibly also kinetic simulations. There is a unique value to each of these approaches, and the community must strive to coordinate better. PMID:25897094

Coronal emission-line polarization from the statistical equilibrium of magnetic sublevels. II. Fe XIV 5303 A

DOE Office of Scientific and Technical Information (OSTI.GOV)

House, L.L.; Querfeld, C.W.; Rees, D.E.

1982-04-15

Coronal magnetic fields influence in the intensity and linear polarization of light scattered by coronal Fe XIV ions. To interpret polarization measurements of Fe XIV 5303 A coronal emission requires a detailed understanding of the dependence of the emitted Stokes vector on coronal magnetic field direction, electron density, and temperature and on height of origin. The required dependence is included in the solutions of statistical equilibrium for the ion which are solved explicitly for 34 magnetic sublevels in both the ground and four excited terms. The full solutions are reduced to equivalent simple analytic forms which clearly show the requiredmore » dependence on coronal conditions. The analytic forms of the reduced solutions are suitable for routine analysis of 5303 green line polarimetric data obtained at Pic du Midi and from the Solar Maximum Mission Coronagraph/Polarimeter.« less

Revitalisation as a Method of Planning Sustainable Development of Old Town Complexes in Historic Towns

NASA Astrophysics Data System (ADS)

Zagroba, Marek; Gawryluk, Dorota

2017-12-01

Old towns in spatial structures of historic towns are the areas which - same as centuries before - serve as the town centres. This is almost invariably true about small towns especially, as the inner town district is more frequently the site where a town was originally located and is often the manifestation of its historic identity. However, functional and spatial problems of many small historic towns arise from the above trend, mostly because of the frequently high density of buildings in the oldest part of a town. The intricate nature of elements creating the structure of a town’s historic centre often calls for certain steps to be taken, which will ensure better exposure of an old town complex against the backdrop of the town’s other areas. Numerous problems need to be solved, not only spatial but also economic and social ones. A town is a living organism, inhabited by people. The key to tackling these issues successfully lies in the creation of such revitalisation programmes that will improve the quality of space and help achieve the sustainable development of inner-town areas in historic towns. The historic centres in the medieval towns of Warmia, a region rich in history and situated in north-eastern Poland, can serve as an example and has been investigated in the following study. All the towns in Warmia located in the Middle Ages, except the capital of the region Olsztyn, can be classified as small urban developments. This group of eleven towns is dominated by the ones whose territorial coverage has not changed considerably since the location and the population ranges from a few thousand to less than twenty thousand. To this day, the historic quarters of these towns have remained the central ones in each town, and their urban structures to a various extent reveal the features characteristic for the period when they were created. The differences are due to the war damage the towns suffered at the end of World War Two and because of the different ways in which they were reconstructed afterwards. In consequence, some elements of the original town master plans have been lost. Revitalisation is an approach whose aim is to improve the quality of space and the ability of inner town areas to function. Revitalisation goes beyond the purely spatial factors, and involves broadly understood economic and social considerations. The conclusions drawn from this research pertain to benefits of using the revitalisation method in planning a sustainable development of urban structures. The development and implementation of revitalisation programmes is a very complex process that takes many years and requires an integrated and interdisciplinary team effort. This method allows us to preserve the identity of historic town areas while enabling them to play functions in the contemporary life of a town.

Particle Acceleration by Cme-driven Shock Waves

NASA Technical Reports Server (NTRS)

Reames, Donald V.

1999-01-01

In the largest solar energetic particle (SEP) events, acceleration occurs at shock waves driven out from the Sun by coronal mass ejections (CMEs). Peak particle intensities are a strong function of CME speed, although the intensities, spectra, and angular distributions of particles escaping the shock are highly modified by scattering on Alfven waves produced by the streaming particles themselves. Element abundances vary in complex ways because ions with different values of Q/A resonate with different parts of the wave spectrum, which varies with space and time. Just recently, we have begun to model these systematic variations theoretically and to explore other consequences of proton-generated waves.

THE CONTRIBUTION OF CORONAL JETS TO THE SOLAR WIND

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lionello, R.; Török, T.; Titov, V. S.

Transient collimated plasma eruptions in the solar corona, commonly known as coronal (or X-ray) jets, are among the most interesting manifestations of solar activity. It has been suggested that these events contribute to the mass and energy content of the corona and solar wind, but the extent of these contributions remains uncertain. We have recently modeled the formation and evolution of coronal jets using a three-dimensional (3D) magnetohydrodynamic (MHD) code with thermodynamics in a large spherical domain that includes the solar wind. Our model is coupled to 3D MHD flux-emergence simulations, i.e., we use boundary conditions provided by such simulationsmore » to drive a time-dependent coronal evolution. The model includes parametric coronal heating, radiative losses, and thermal conduction, which enables us to simulate the dynamics and plasma properties of coronal jets in a more realistic manner than done so far. Here, we employ these simulations to calculate the amount of mass and energy transported by coronal jets into the outer corona and inner heliosphere. Based on observed jet-occurrence rates, we then estimate the total contribution of coronal jets to the mass and energy content of the solar wind to (0.4–3.0)% and (0.3–1.0)%, respectively. Our results are largely consistent with the few previous rough estimates obtained from observations, supporting the conjecture that coronal jets provide only a small amount of mass and energy to the solar wind. We emphasize, however, that more advanced observations and simulations (including parametric studies) are needed to substantiate this conjecture.« less

Coronal hole evolution by sudden large scale changes

NASA Technical Reports Server (NTRS)

Nolte, J. T.; Gerassimenko, M.; Krieger, A. S.; Solodyna, C. V.

1978-01-01

Sudden shifts in coronal-hole boundaries observed by the S-054 X-ray telescope on Skylab between May and November, 1973, within 1 day of CMP of the holes, at latitudes not exceeding 40 deg, are compared with the long-term evolution of coronal-hole area. It is found that large-scale shifts in boundary locations can account for most if not all of the evolution of coronal holes. The temporal and spatial scales of these large-scale changes imply that they are the results of a physical process occurring in the corona. It is concluded that coronal holes evolve by magnetic-field lines' opening when the holes are growing, and by fields' closing as the holes shrink.

Coronal temperatures of selected active cool stars as derived from low resolution Einstein observations

NASA Technical Reports Server (NTRS)

Vilhu, Osmi; Linsky, Jeffrey L.

1990-01-01

Mean coronal temperatures of some active G-K stars were derived from Rev1-processed Einstein-observatory's IPC-spectra. The combined X-ray and transition region emission line data are in rough agreement with static coronal loop models. Although the sample is too small to derive any statistically significant conclusions, it suggests that the mean coronal temperature depends linearly on the inverse Rossby-number, with saturation at short rotation periods.

Recurring coronal holes and their rotation rates during the solar cycles 22-24

NASA Astrophysics Data System (ADS)

Prabhu, K.; Ravindra, B.; Hegde, Manjunath; Doddamani, Vijayakumar H.

2018-05-01

Coronal holes (CHs) play a significant role in making the Earth geo-magnetically active during the declining and minimum phases of the solar cycle. In this study, we analysed the evolutionary characteristics of the Recurring CHs from the year 1992 to 2016. The extended minimum of Solar Cycle 23 shows unusual characteristics in the number of persistent coronal holes in the mid- and low-latitude regions of the Sun. Carrington rotation maps of He 10830 Å and EUV 195 Å observations are used to identify the Coronal holes. The latitude distribution of the RCHs shows that most of them are appeared between ± 20° latitudes. In this period, more number of recurring coronal holes appeared in and around 100° and 200° Carrington longitudes. The large sized coronal holes lived for shorter period and they appeared close to the equator. From the area distribution over the latitude considered, it shows that more number of recurring coronal holes with area <10^{21} cm2 appeared in the southern latitude close to the equator. The rotation rates calculated from the RCHs appeared between ± 60° latitude shows rigid body characteristics. The derived rotational profiles of the coronal holes show that they have anchored to a depth well below the tachocline of the interior, and compares well with the helioseismology results.

On the Detection of Coronal Dimmings and the Extraction of Their Characteristic Properties

NASA Astrophysics Data System (ADS)

Dissauer, K.; Veronig, A. M.; Temmer, M.; Podladchikova, T.; Vanninathan, K.

2018-03-01

Coronal dimmings are distinct phenomena associated with coronal mass ejections (CMEs). The study of coronal dimmings and the extraction of their characteristic parameters help us to obtain additional information regarding CMEs, especially on the initiation and early evolution of Earth-directed CMEs. We present a new approach to detect coronal dimming regions based on a thresholding technique applied on logarithmic base-ratio images. Characteristic dimming parameters describing the dynamics, morphology, magnetic properties, and the brightness of coronal dimming regions are extracted by cumulatively summing newly dimmed pixels over time. It is also demonstrated how core dimming regions are identified as a subset of the overall identified dimming region. We successfully apply our method to two well-observed coronal dimming events. For both events, the core dimming regions are identified and the spatial evolution of the dimming area reveals the expansion of the dimming region around these footpoints. We also show that in the early impulsive phase of the dimming expansion the total unsigned magnetic flux involved in the dimming regions is balanced and that up to 30% of this flux results from the localized core dimming regions. Furthermore, the onset in the profile of the area growth rate is cotemporal with the start of the associated flares and in one case also with the fast rise of the CME, indicating a strong relationship of coronal dimmings with both flares and CMEs.

Observations and Numerical Models of Solar Coronal Heating Associated with Spicules

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pontieu, B. De; Martinez-Sykora, J.; Moortel, I. De

Spicules have been proposed as significant contributors to the mass and energy balance of the corona. While previous observations have provided a glimpse of short-lived transient brightenings in the corona that are associated with spicules, these observations have been contested and are the subject of a vigorous debate both on the modeling and the observational side. Therefore, it remains unclear whether plasma is heated to coronal temperatures in association with spicules. We use high-resolution observations of the chromosphere and transition region (TR) with the Interface Region Imaging Spectrograph and of the corona with the Atmospheric Imaging Assembly on board themore » Solar Dynamics Observatory to show evidence of the formation of coronal structures associated with spicular mass ejections and heating of plasma to TR and coronal temperatures. Our observations suggest that a significant fraction of the highly dynamic loop fan environment associated with plage regions may be the result of the formation of such new coronal strands, a process that previously had been interpreted as the propagation of transient propagating coronal disturbances. Our observations are supported by 2.5D radiative MHD simulations that show heating to coronal temperatures in association with spicules. Our results suggest that heating and strong flows play an important role in maintaining the substructure of loop fans, in addition to the waves that permeate this low coronal environment.« less

Genesis Solar Wind Interstream, Coronal Hole and Coronal Mass Ejection Samples: Update on Availability and Condition

NASA Technical Reports Server (NTRS)

Allton, J. H.; Gonzalez, C. P.; Allums, K. K.

2017-01-01

Recent refinement of analysis of ACE/SWICS data (Advanced Composition Explorer/Solar Wind Ion Composition Spectrometer) and of onboard data for Genesis Discovery Mission of 3 regimes of solar wind at Earth-Sun L1 make it an appropriate time to update the availability and condition of Genesis samples specifically collected in these three regimes and currently curated at Johnson Space Center. ACE/SWICS spacecraft data indicate that solar wind flow types emanating from the interstream regions, from coronal holes and from coronal mass ejections are elementally and isotopically fractionated in different ways from the solar photosphere, and that correction of solar wind values to photosphere values is non-trivial. Returned Genesis solar wind samples captured very different kinds of information about these three regimes than spacecraft data. Samples were collected from 11/30/2001 to 4/1/2004 on the declining phase of solar cycle 23. Meshik, et al is an example of precision attainable. Earlier high precision laboratory analyses of noble gases collected in the interstream, coronal hole and coronal mass ejection regimes speak to degree of fractionation in solar wind formation and models that laboratory data support. The current availability and condition of samples captured on collector plates during interstream slow solar wind, coronal hole high speed solar wind and coronal mass ejections are de-scribed here for potential users of these samples.

Plasma properties and magnetic field structure of the solar corona, based on coordinated Max 1991 observations from SERTS, the VLA, and magnetographs

NASA Technical Reports Server (NTRS)

Brosius, Jeffrey W.

1995-01-01

The purposes of this investigation are to use existing, calibrated, coaligned sets of coordinated multiwaveband observations of the Sun to determine the coronal magnetic field strength and structure, and interpret the collective observations in terms of a self-consistent model of the coronal plasma and magnetic field. This information is vital to understanding processes such as coronal heating, solar wind acceleration, pre-flare energy storage, and active region evolution. Understanding these processes is the central theme of Max '91, the NASA-supported series of solar observing campaigns under which the observations acquired for this work were obtained. The observations came from NASA/GSFC's Solar EUV Rocket Telescope and Spectrograph (SERTS), the Very Large Array (VLA), and magnetographs. The technique of calculating the coronal magnetic field is to establish the contributions to the microwave emission from the two main emission mechanisms: thermal bremsstrahlung and thermal gyroemission. This is done by using the EUV emission to determine values of the coronal plasma quantities needed to calculate the thermal bremsstrahlung contribution to the microwave emission. Once the microwave emission mechanism(s) are determined, the coronal magnetic field can be calculated. A comparison of the coronal magnetic field derived from the coordinated multiwaveband observations with extrapolations from photospheric magnetograms will provide insight into the nature of the coronal magnetic field.

Coronal Jets in Closed Magnetic Regions on the Sun

NASA Astrophysics Data System (ADS)

Wyper, Peter Fraser; DeVore, C. R.

2015-04-01

Coronal jets are dynamic, collimated structures observed in solar EUV and X-ray emission. They appear predominantly in the open field of coronal holes, but are also observed in areas of closed field, especially active regions. A common feature of coronal jets is that they originate from the field above a parasitic polarity of opposite sign to the surrounding field. Some process - such as instability onset or flux emergence - induces explosive reconnection between the closed “anemone” field and the surrounding open field that generates the jet. The lesser number of coronal jets in closed-field regions suggests a possible stabilizing effect of the closed configuration with respect to coronal jet formation. If the scale of the jet region is small compared with the background loop length, as in for example type II spicules, the nearby magnetic field may be treated as locally open. As such, one would expect that if a stabilizing effect exists it becomes most apparent as the scale of the anemone region approaches that of the background coronal loops.To investigate if coronal jets are indeed suppressed along shorter coronal loops, we performed a number of simulations of jets driven by a rotation of the parasitic polarity (as in the previous open-jet calculations by Pariat et. al 2009, 2010, 2015) embedded in a large-scale closed bipolar field. The simulations were performed with the state of the art Adaptively Refined Magnetohydrodynamics Solver. We will report here how the magnetic configuration above the anemone region determines the nature of the jet, when it is triggered, and how much of the stored magnetic energy is released. We show that regions in which the background field and the parasitic polarity region are of comparable scale naturally suppress explosive energy release. We will also show how in the post-jet relaxation phase a combination of confined MHD waves and weak current layers are generated by the jet along the background coronal loops, both of which may have implications for coronal heating.This work was supported by an appointment to the NASA Postdoctoral Program (P.F.W.) and by NASA’s Living With a Star Targeted Research and Technology program (C.R.D.).

Small Towns in a Rural Area: A Study of the Problems of Small Towns in Idaho. Idaho Agricultural Experiment Station Research Bulletin No. 91, April 1976.

ERIC Educational Resources Information Center

Hamilton, J. R.; And Others

Using aggregate data from several Idaho counties and towns, the study examined the economic forces which pressure small town people and merchants--pressures which ultimately shape and will shape small towns in areas like Idaho. Six towns chosen for intensive study were Priest River, Cottonwood, Riggins, Shoshone, Oakley, and Malad. Focusing on…

78 FR 77481 - Proposed Flood Hazard Determinations

Federal Register 2010, 2011, 2012, 2013, 2014

2013-12-23

.... Town of Bethel Secretary's Residence, 908 West Street, Bethel, DE 19931. Town of Blades Town Hall, 20 West Fourth Street, Blades, DE 19973. Town of Bridgeville Town Hall, 101 North Main Street, Bridgeville... Township Office, 1224 Buffalo Run Road, Bellefonte, PA 16823. Essex County, Virginia, and Incorporated...

78 FR 14577 - Final Flood Hazard Determinations

Federal Register 2010, 2011, 2012, 2013, 2014

2013-03-06

... above. FOR FURTHER INFORMATION CONTACT: Luis Rodriguez, Chief, Engineering Management Branch, Federal... Office, 2 Main Street, Livermore Falls, ME 04254. Town of Mechanic Falls Town Office, 108 Lewiston Street, Mechanic Falls, ME 04256. Town of Minot Town Office, 329 Woodman Hill Road, Minot, ME 04258. Town of Poland...

Activated carbon fiber felt and polymer fiber as biofilm carrier in a modified University of Cape Town process for sewage treatment.

PubMed

Zhou, Dongkai

2013-01-01

Biofilms on fiber-based carriers have attracted much concern in wastewater treatment processes recently. In this study: (1) a novel sandwich structure fiber-based biofilm carrier was produced, which consisted of an inner core composed of polyacrylonitrile-based activated carbon fiber felt (PAN-ACFF) and an outer coat made of polyester reticular cloth with polypropylene fiber loops; (2) the novel carrier was filled in a step-feeding pilot-scale modified University of Cape Town process (MUCT) for sewage treatment; the MUCT contained a series of pre-anoxic/anaerobic/anoxic-1/anoxic-2/oxic tanks, wherein nitrification liquor was recycled to the anoxic-2 tank and an extra liquor return from the anoxic-1 to the pre-anoxic tank was set up; and (3) the removal efficiencies of chemical oxygen demand (COD), total nitrogen (TN) and total phosphorus (TP) were continuously tested for two periods as operational parameters alternated. The optimum values were collected in Period II, when the influent loads were 2,100.6 ± 120.3 gCOD/(d m(3)), 205.5 ± 20.4 gTN/(d m(3)), 39.9 ± 3.9 gTP/(d m(3)), the removal percentages were 93.1 ± 1.1% of COD, 39.4 ± 3.5% of TN, and 84.6 ± 3.4% of TP. For COD, NH4(+)-N, and TP, the specific removal loads of filler were 291.5 ± 18.2, 22.9 ± 3.1, 4.8 ± 0.5 (g d)/kg.

Coronal Magnetism: Hanle Effect in UV and IR Spectral Lines

NASA Astrophysics Data System (ADS)

Raouafi, N. E.; Riley, P.

2014-12-01

The plasma thermodynamics in the solar upper atmosphere, particularly in the corona, are dominated by the magnetic field, which controls the flow and dissipation of energy. The relative lack of knowledge of the coronal vector magnetic field is a major handicap for the progress in coronal physics. This makes the development of measurement methods of coronal magnetic fields a high priority in solar physics. The Hanle effect in the UV and IR spectral lines is a largely unexplored diagnostic. Here we use magnetohydrodynamic (MHD) simulations to study the magnitude of the signal to be expected for typical coronal magnetic fields for selected spectral lines in the UV and IR wavelength ranges, namely the H I Lyman series (i.e., α, β, and γ), O VI 103.2 nm line, and the He I 1083 nm line. We show that the selected lines may be useful for the diagnostic of coronal magnetic fields. We also show that the combination of polarization measurements of spectral lines with different sensitivities to the Hanle effect may be most appropriate for the interpretation of the data. We propose that UV coronal magnetic field mapper should be a central part of the science payload of any future spacebased solar observatory.

75 FR 29258 - Proposed Flood Elevation Determinations

Federal Register 2010, 2011, 2012, 2013, 2014

2010-05-25

... Barker, Town Reach 1. of Chenango, Town of Dickinson, Town of Fenton, Village of Port Dickinson... River. Town of Fenton. Approximately 2.5 miles None +1011 upstream of Ballyhack Road. Page Brook At the confluence with +876 +878 Town of Fenton. the Chenango River. Approximately 630 feet +877 +878 downstream of...

75 FR 8814 - Final Flood Elevation Determinations

Federal Register 2010, 2011, 2012, 2013, 2014

2010-02-26

... +1014 Town of Marathon, Village downstream of Main of Marathon. Street. Approximately 0.85 mile +1023..., Cortland, NY 13045. Town of Marathon Maps are available for inspection at the Town of Marathon Highway Department, 16 Brink Street, Marathon, NY 13803. Town of Preble Maps are available for inspection at the Town...

NO[sub x] reduction by sulfur tolerant coronal-catalytic apparatus and method

DOEpatents

Mathur, V.K.; Breault, R.W.; McLarnon, C.R.; Medros, F.G.

1992-09-15

This invention presents an NO[sub x] environment effective reduction apparatus comprising a sulfur tolerant coronal-catalyst such as high dielectric coronal-catalysts like glass wool, ceramic-glass wool or zirconium glass wool and method of use. In one embodiment the invention comprises an NO[sub x] reduction apparatus of sulfur tolerant coronal-catalyst adapted and configured for hypercritical presentation to an NO[sub x] bearing gas stream at a minimum of at least about 75 watts/cubic meter. 7 figs.

NO.sub.x reduction by sulfur tolerant coronal-catalytic apparatus and method

DOEpatents

Mathur, Virendra K.; Breault, Ronald W.; McLarnon, Christopher R.; Medros, Frank G.

1993-01-01

This invention presents an NO.sub.x environment effective reduction apparatus comprising a sulfur tolerant coronal-catalyst such as high dielectric coronal-catalysts like glass wool, ceramic-glass wool or zirconium glass wool and method of use. In one embodiment the invention comprises an NO.sub.x reduction apparatus of sulfur tolerant coronal-catalyst adapted and configured for hypercritical presentation to an NO.sub.x bearing gas stream at a minimum of at least about 75 watts/cubic meter.

NO.sub.x reduction by sulfur tolerant coronal-catalytic apparatus and method

DOEpatents

Mathur, Virendra K.; Breault, Ronald W.; McLarnon, Christopher R.; Medros, Frank G.

1992-01-01

This invention presents an NO.sub.x environment effective reduction apparatus comprising a sulfur tolerant coronal-catalyst such as high dielectric coronal-catalysts like glass wool, ceramic-glass wool or zirconium glass wool and method of use. In one embodiment the invention comprises an NO.sub.x reduction apparatus of sulfur tolerant coronal-catalyst adapted and configured for hypercritical presentation to an NO.sub.x bearing gas stream at a minimum of at least about 75 watts/cubic meter.

NOx reduction by sulfur tolerant coronal-catalytic apparatus and method

DOEpatents

Mathur, V.K.; Breault, R.W.; McLarnon, C.R.; Medros, F.G.

1993-08-31

This invention presents an NO[sub x] environment effective reduction apparatus comprising a sulfur tolerant coronal-catalyst such as high dielectric coronal-catalysts like glass wool, ceramic-glass wool or zirconium glass wool and method of use. In one embodiment the invention comprises an NO[sub x] reduction apparatus of sulfur tolerant coronal-catalyst adapted and configured for hypercritical presentation to an NO[sub x] bearing gas stream at a minimum of at least about 75 watts/cubic meter.

An Airborne Infrared Spectrometer for Solar Eclipse Observations

NASA Astrophysics Data System (ADS)

Samra, Jenna; DeLuca, Edward E.; Golub, Leon; Cheimets, Peter; Philip, Judge

2016-05-01

The airborne infrared spectrometer (AIR-Spec) is an innovative solar spectrometer that will observe the 2017 solar eclipse from the NSF/NCAR High-Performance Instrumented Airborne Platform for Environmental Research (HIAPER). AIR-Spec will image five infrared coronal emission lines to determine whether they may be useful probes of coronal magnetism.The solar magnetic field provides the free energy that controls coronal heating, structure, and dynamics. Energy stored in coronal magnetic fields is released in flares and coronal mass ejections and ultimately drives space weather. Therefore, direct coronal field measurements have significant potential to enhance understanding of coronal dynamics and improve solar forecasting models. Of particular interest are observations of field lines in the transitional region between closed and open flux systems, providing important information on the origin of the slow solar wind.While current instruments routinely observe only the photospheric and chromospheric magnetic fields, AIR-Spec will take a step toward the direct observation of coronal fields by measuring plasma emission in the infrared at high spatial and spectral resolution. During the total solar eclipse of 2017, AIR-Spec will observe five magnetically sensitive coronal emission lines between 1.4 and 4 µm from the HIAPER Gulfstream V at an altitude above 14.9 km. The instrument will measure emission line intensity, width, and Doppler shift, map the spatial distribution of infrared emitting plasma, and search for waves in the emission line velocities.AIR-Spec consists of an optical system (feed telescope, grating spectrometer, and infrared detector) and an image stabilization system, which uses a fast steering mirror to correct the line-of-sight for platform perturbations. To ensure that the instrument meets its research goals, both systems are undergoing extensive performance modeling and testing. These results are shown with reference to the science requirements.

Transverse Oscillations of Coronal Loops

NASA Astrophysics Data System (ADS)

Ruderman, Michael S.; Erdélyi, Robert

2009-12-01

On 14 July 1998 TRACE observed transverse oscillations of a coronal loop generated by an external disturbance most probably caused by a solar flare. These oscillations were interpreted as standing fast kink waves in a magnetic flux tube. Firstly, in this review we embark on the discussion of the theory of waves and oscillations in a homogeneous straight magnetic cylinder with the particular emphasis on fast kink waves. Next, we consider the effects of stratification, loop expansion, loop curvature, non-circular cross-section, loop shape and magnetic twist. An important property of observed transverse coronal loop oscillations is their fast damping. We briefly review the different mechanisms suggested for explaining the rapid damping phenomenon. After that we concentrate on damping due to resonant absorption. We describe the latest analytical results obtained with the use of thin transition layer approximation, and then compare these results with numerical findings obtained for arbitrary density variation inside the flux tube. Very often collective oscillations of an array of coronal magnetic loops are observed. It is natural to start studying this phenomenon from the system of two coronal loops. We describe very recent analytical and numerical results of studying collective oscillations of two parallel homogeneous coronal loops. The implication of the theoretical results for coronal seismology is briefly discussed. We describe the estimates of magnetic field magnitude obtained from the observed fundamental frequency of oscillations, and the estimates of the coronal scale height obtained using the simultaneous observations of the fundamental frequency and the frequency of the first overtone of kink oscillations. In the last part of the review we summarise the most outstanding and acute problems in the theory of the coronal loop transverse oscillations.

Deformation and deceleration of coronal wave

NASA Astrophysics Data System (ADS)

Xue, Z. K.; Qu, Z. Q.; Yan, X. L.; Zhao, L.; Ma, L.

2013-08-01

Aims: We studied the kinematics and morphology of two coronal waves to better understand the nature and origin of coronal waves. Methods: Using multi-wavelength observations of the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory (SDO) and the Extreme Ultraviolet Imager (EUVI) on board the twin spacecraft Solar-TErrestrial RElations Observatory (STEREO), we present morphological and dynamic characteristics of consecutive coronal waves on 2011 March 24. We also show the coronal magnetic field based on the potential field source surface model. Results: This event contains several interesting aspects. The first coronal wave initially appeared after a surge-like eruption. Its front was changed and deformed significantly from a convex shape to a line-shaped appearance, and then to a concave configuration during its propagation to the northwest. The initial speeds ranged from 947 km s-1 to 560 km s-1. The first wave decelerated significantly after it passed through a filament channel. After the deceleration, the final propagation speeds of the wave were from 430 km s-1 to 312 km s-1. The second wave was found to appear after the first wave in the northwest side of the filament channel. Its wave front was more diffused and the speed was around 250 km s-1, much slower than that of the first wave. Conclusions: The deformation of the first coronal wave was caused by the different speeds along different paths. The sudden deceleration implies that the refraction of the first wave took place at the boundary of the filament channel. The event provides evidence that the first coronal wave may be a coronal MHD shock wave, and the second wave may be the apparent propagation of the brightenings caused by successive stretching of the magnetic field lines.

Energy released by the interaction of coronal magnetic fields

NASA Technical Reports Server (NTRS)

Sheeley, N. R., Jr.

1976-01-01

Comparisons between coronal spectroheliograms and photospheric magnetograms are presented to support the idea that as coronal magnetic fields interact, a process of field-line reconnection usually takes place as a natural way of preventing magnetic stresses from building up in the lower corona. This suggests that the energy which would have been stored in stressed fields is continuously released as kinetic energy of material being driven aside to make way for the reconnecting fields. However, this kinetic energy is negligible compared with the thermal energy of the coronal plasma. Therefore, it appears that these slow adjustments of coronal magnetic fields cannot account for even the normal heating of the corona, much less the energetic events associated with solar flares.

Resonant electrodynamic heating of stellar coronal loops: An LRC circuit analogue

NASA Technical Reports Server (NTRS)

Ionson, J. A.

1980-01-01

The electrodynamic coupling of stellar coronal loops to underlying beta velocity fields. A rigorous analysis revealed that the physics can be represented by a simple yet equivalent LRC circuit analogue. This analogue points to the existence of global structure oscillations which resonantly excite internal field line oscillations at a spatial resonance within the coronal loop. Although the width of this spatial resonance, as well as the induced currents and coronal velocity field, explicitly depend upon viscosity and resistivity, the resonant form of the generalized electrodynamic heating function is virtually independent of irreversibilities. This is a classic feature of high quality resonators that are externally driven by a broad band source of spectral power. Applications to solar coronal loops result in remarkable agreement with observations.

The temperature structure, mass, and energy flow in the corona and inner solar wind

NASA Technical Reports Server (NTRS)

Withbroe, George L.

1988-01-01

Remote-sensing and in situ data are used to constrain a radiative energy balance model in order to study the radial variations of coronal temperatures, densities, and outflow speeds in several types of coronal holes and in an unstructured quiet region of the corona. A one-fluid solar wind model is used which takes into account the effects of radiative and inward conductive losses in the low corona and the chromospheric-coronal transition region. The results show that the total nonradiative energy input in magnetically open coronal regions is 5 + or - 10 to the 5th ergs/sq cm, and that most of the energy heating the coronal plasma is dissipated within 2 solar radii of the solar surface.

Observational Consequences of Coronal Heating Mechanisms

NASA Technical Reports Server (NTRS)

Winebarger, Amy R.; Cirtain, Jonathan C.; Golub, Leon; Kobayashi, Ken

2014-01-01

The coronal heating problem remains unsolved today, 80 years after its discovery, despite 50 years of suborbital and orbital coronal observatories. Tens of theoretical coronal heating mechanisms have been suggested, but only a few have been able to be ruled out. In this talk, we will explore the reasons for the slow progress and discuss the measurements that will be needed for potential breakthrough, including imaging the solar corona at small spatial scales, measuring the chromospheric magnetic fields, and detecting the presence of high temperature, low emission measure plasma. We will discuss three sounding rocket instruments developed to make these measurements: the High resolution Resolution Coronal Imager (Hi-C), the Chromospheric Lyman-Alpha Spectropolarimeter (CLASP), and the Marshall Grazing Incidence X-ray Spectrometer (MaGIXS).

New Instruments to Isolate the Coronal Heating Mechanism

NASA Technical Reports Server (NTRS)

Winebarger, Amy

2014-01-01

The coronal heating problem remains unsolved today, 80 years after its discovery, despite 50 years of suborbital and orbital coronal observatories. Tens of theoretical coronal heating mechanisms have been suggested, but only a few have been able to be ruled out. In this talk, we will explore the reasons for the slow progress and discuss the measurements that will be needed for potential breakthrough, including imaging the solar corona at small spatial scales, measuring the chromospheric magnetic fields, and detecting the presence of high temperature, low-emission measure plasma. We will discuss three sounding rocket instruments developed to make these measurements: the High-resolution Resolution Coronal Imager (Hi-C), the Chromospheric Lyman-Alpha Spectropolarimeter (CLASP), and the Marshall Grazing Incidence X-ray Spectrometer (MaGIXS).

Detection of the nipple in automated 3D breast ultrasound using coronal slab-average-projection and cumulative probability map

NASA Astrophysics Data System (ADS)

Kim, Hannah; Hong, Helen

2014-03-01

We propose an automatic method for nipple detection on 3D automated breast ultrasound (3D ABUS) images using coronal slab-average-projection and cumulative probability map. First, to identify coronal images that appeared remarkable distinction between nipple-areola region and skin, skewness of each coronal image is measured and the negatively skewed images are selected. Then, coronal slab-average-projection image is reformatted from selected images. Second, to localize nipple-areola region, elliptical ROI covering nipple-areola region is detected using Hough ellipse transform in coronal slab-average-projection image. Finally, to separate the nipple from areola region, 3D Otsu's thresholding is applied to the elliptical ROI and cumulative probability map in the elliptical ROI is generated by assigning high probability to low intensity region. False detected small components are eliminated using morphological opening and the center point of detected nipple region is calculated. Experimental results show that our method provides 94.4% nipple detection rate.

The cyclical variation of energy flux and photospheric magnetic field strength from coronal holes

NASA Technical Reports Server (NTRS)

Webb, D. F.; Davis, J. M.

1985-01-01

The average soft X-ray emission from coronal holes observed on images obtained during rocket flights from 1974 to 1981 is measured. The variation of this emission over the solar cycle was then compared with photospheric magnetic flux measurements within coronal holes over the same period. It was found that coronal hole soft X-ray emission could be detected and that this emission appeared to increase with the rise of the sunspot cycle from activity minimum to maximum. These quantitative results confirmed previous suggestions that the coronal brightness contrast between holes and large-scale structure decreased during this period of the cycle. Gas pressures at the hole base were estimated for assumed temperatures and found to vary from about 0.03 dyne/sq cm in 1974 to 0.35 dyne/sq cm in 1981. The increase in coronal hole X-ray emission was accompanied by a similar trend in the surface magnetic flux of near-equatorial holes between 1975 and 1980 (Harvey et al., 1982).

Coronal Structures in Cool Stars: XMM-NEWTON Hybrid Stars and Coronal Evolution

NASA Technical Reports Server (NTRS)

Dupree, Andrea K.; Mushotzky, Richard (Technical Monitor)

2003-01-01

This program addresses the evolution of stellar coronas by comparing a solar-like corona in the supergiant Beta Dra (G2 Ib-IIa) to the corona in the allegedly more evolved state of a hybrid star, alpha TrA (K2 II-III). Because the hybrid star has a massive wind, it appears likely that the corona will be cooler and less dense as the magnetic loop structures are no longer closed. By analogy with solar coronal holes, when the topology of the magnetic field is configured with open magnetic structures, both the coronal temperature and density are lower than in atmospheres dominated by closed loops. The hybrid stars assume a pivotal role in the definition of coronal evolution, atmospheric heating processes and mechanisms to drive winds of cool stars. We are attempting to determine if this model of coronal evolution is correct by using XMM-NEWTON RGS spectra for the 2 targets we were allocated through the Guest Observer program.

Coronal ``Wave'': Magnetic Footprint of a Coronal Mass Ejection?

NASA Astrophysics Data System (ADS)

Attrill, Gemma D. R.; Harra, Louise K.; van Driel-Gesztelyi, Lidia; Démoulin, Pascal

2007-02-01

We investigate the properties of two ``classical'' EUV Imaging Telescope (EIT) coronal waves. The two source regions of the associated coronal mass ejections (CMEs) possess opposite helicities, and the coronal waves display rotations in opposite senses. We observe deep core dimmings near the flare site and also widespread diffuse dimming, accompanying the expansion of the EIT wave. We also report a new property of these EIT waves, namely, that they display dual brightenings: persistent ones at the outermost edge of the core dimming regions and simultaneously diffuse brightenings constituting the leading edge of the coronal wave, surrounding the expanding diffuse dimmings. We show that such behavior is consistent with a diffuse EIT wave being the magnetic footprint of a CME. We propose a new mechanism where driven magnetic reconnections between the skirt of the expanding CME magnetic field and quiet-Sun magnetic loops generate the observed bright diffuse front. The dual brightenings and the widespread diffuse dimming are identified as innate characteristics of this process.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fang, X.; Xia, C.; Keppens, R.

We present the first multidimensional, magnetohydrodynamic simulations that capture the initial formation and long-term sustainment of the enigmatic coronal rain phenomenon. We demonstrate how thermal instability can induce a spectacular display of in situ forming blob-like condensations which then start their intimate ballet on top of initially linear force-free arcades. Our magnetic arcades host a chromospheric, transition region, and coronal plasma. Following coronal rain dynamics for over 80 minutes of physical time, we collect enough statistics to quantify blob widths, lengths, velocity distributions, and other characteristics which directly match modern observational knowledge. Our virtual coronal rain displays the deformation ofmore » blobs into V-shaped features, interactions of blobs due to mostly pressure-mediated levitations, and gives the first views of blobs that evaporate in situ or are siphoned over the apex of the background arcade. Our simulations pave the way for systematic surveys of coronal rain showers in true multidimensional settings to connect parameterized heating prescriptions with rain statistics, ultimately allowing us to quantify the coronal heating input.« less

Solar radio bursts of spectral type II, coronal shocks, and optical coronal transients

NASA Technical Reports Server (NTRS)

Maxwell, A.; Dryer, M.

1981-01-01

An examination is presented of the association of solar radio bursts of spectral type II and coronal shocks with solar flare ejecta observed in H-alpha, the green coronal line, and white-light coronagraphs. It is suggested that fast-moving optical coronal transients should for the most part be identified with piston-type phenomena well behind the outward-traveling shock waves that generate type II radio bursts. A general model is presented which relates type II radio bursts and coronal shocks to optically observed ejecta and consists of three main velocity regimes: (1) a quasi-hemispherical shock wave moving outward from the flare at speeds of 1000-2000 km/sec and Alfven Mach number of about 1.5; (2) the velocity of the piston driving the shock, on the order of 0.8 that of the shock; and (3) the regime of the slower-moving H-alpha ejecta, with velocities of 300-500 km/sec.

The mean coronal magnetic field determined from Helios Faraday rotation measurements

NASA Technical Reports Server (NTRS)

Patzold, M.; Bird, M. K.; Volland, H.; Levy, G. S.; Seidel, B. L.; Stelzried, C. T.

1987-01-01

Coronal Faraday rotation of the linearly polarized carrier signals of the Helios spacecraft was recorded during the regularly occurring solar occultations over almost a complete solar cycle from 1975 to 1984. These measurements are used to determine the average strength and radial variation of the coronal magnetic field at solar minimum at solar distances from 3-10 solar radii, i.e., the range over which the complex fields at the coronal base are transformed into the interplanetary spiral. The mean coronal magnetic field in 1975-1976 was found to decrease with radial distance according to r exp-alpha, where alpha = 2.7 + or - 0.2. The mean field magnitude was 1.0 + or - 0.5 x 10 to the -5th tesla at a nominal solar distance of 5 solar radii. Possibly higher magnetic field strengths were indicated at solar maximum, but a lack of data prevented a statistical determination of the mean coronal field during this epoch.

Designing a Health Clinic for Prairie City, Oregon: Revitalizing Main Street in Small, Remote Towns.

ERIC Educational Resources Information Center

Young, Jenny E.

1995-01-01

A small town designed a health clinic to entice a health care practitioner to locate in the town, increase the town's economic feasibility, generate local jobs, and stimulate business in the downtown. The design is important to achieving these goals by continuing and enhancing the town's character. (TD)

Impulsively Generated Wave Trains in Coronal Structures. II. Effects of Transverse Structuring on Sausage Waves in Pressurelesss Slabs

NASA Astrophysics Data System (ADS)

Li, Bo; Guo, Ming-Zhe; Yu, Hui; Chen, Shao-Xia

2018-03-01

Impulsively generated sausage wave trains in coronal structures are important for interpreting a substantial number of observations of quasi-periodic signals with quasi-periods of order seconds. We have previously shown that the Morlet spectra of these wave trains in coronal tubes depend crucially on the dispersive properties of trapped sausage waves, the existence of cutoff axial wavenumbers, and the monotonicity of the dependence of the axial group speed on the axial wavenumber in particular. This study examines the difference a slab geometry may introduce, for which purpose we conduct a comprehensive eigenmode analysis, both analytically and numerically, on trapped sausage modes in coronal slabs with a considerable number of density profiles. For the profile descriptions examined, coronal slabs can trap sausage waves with longer axial wavelengths, and the group speed approaches the internal Alfvén speed more rapidly at large wavenumbers in the cylindrical case. However, common to both geometries, cutoff wavenumbers exist only when the density profile falls sufficiently rapidly at distances far from coronal structures. Likewise, the monotonicity of the group speed curves depends critically on the profile steepness right at the structure axis. Furthermore, the Morlet spectra of the wave trains are shaped by the group speed curves for coronal slabs and tubes alike. Consequently, we conclude that these spectra have the potential for inferring the subresolution density structuring inside coronal structures, although their detection requires an instrumental cadence of better than ∼1 s.

Do solar decimetric spikes originate in coronal X-ray sources?

NASA Astrophysics Data System (ADS)

Battaglia, M.; Benz, A. O.

2009-06-01

Context: In the standard solar flare scenario, a large number of particles are accelerated in the corona. Nonthermal electrons emit both X-rays and radio waves. Thus, correlated signatures of the acceleration process are predicted at both wavelengths, coinciding either close to the footpoints of a magnetic loop or near the coronal X-ray source. Aims: We attempt to study the spatial connection between coronal X-ray emission and decimetric radio spikes to determine the site and geometry of the acceleration process. Methods: The positions of radio-spike sources and coronal X-ray sources are determined and analyzed in a well-observed limb event. Radio spikes are identified in observations from the Phoenix-2 spectrometer. Data from the Nançay radioheliograph are used to determine the position of the radio spikes. RHESSI images in soft and hard X-ray wavelengths are used to determine the X-ray flare geometry. Those observations are complemented by images from GOES/SXI. Results: We find that the radio emission originates at altitudes much higher than the coronal X-ray source, having an offset from the coronal X-ray source amounting to 90´´ and to 113´´ and 131´´ from the two footpoints, averaged over time and frequency. Conclusions: Decimetric spikes do not originate from coronal X-ray flare sources contrary to previous expectations. However, the observations suggest a causal link between the coronal X-ray source, related to the major energy release site, and simultaneous activity in the higher corona.

Design and Fabrication of the All-Reflecting H-Lyman alpha Coronagraph/Polarimeter

NASA Technical Reports Server (NTRS)

Hoover, Richard B.; Johnson, R. Barry; Fineschi, Silvano; Walker, Arthur B. C., Jr.; Baker, Phillip C.; Zukic , Muamer; Kim, Jongmin

1993-01-01

We have designed, analyzed, and are now fabricating an All-Reflecting H-Lyman alpha Coronagraph/Polarimeter for solar research. This new instrument operates in a narrow bandpass centered at lambda 1215.7 A-the neutral hydrogen Lyman alpha (Ly-alpha) line. It is shorter and faster than the telescope which produced solar Ly-alpha images as a part of the MSSTA payload that was launched on May 13, 1991. The Ly-alpha line is produced and linearly polarized in the solar corona by resonance scattering, and the presence of a magnetic field modifies this polarization according to the Hanle effect. The Lyman alpha Coronagraph/Polarimeter instrument has been designed to measure coronal magnetic fields by interpreting, via the Hanle effect, the measured linear polarization of the coronal Ly-alpha line. Ultrasmooth mirrors, polarizers, and filters are being flow-polished for this instrument from CVD silicon carbide substrates. These optical components will be coated using advanced induced transmission and absorption thin film multilayer coatings, to optimize the reflectivity and polarization properties at 1215.7 A. We describe some of the solar imaging results obtained with the MSSTA Lyman alpha coronagraph. We also discuss the optical design parameters and fabrication plans for the All-Reflecting H-Lyman alpha Coronagraph/Polarimeter.

[Cervicobrachial disorders in school-lunch female cooks].

PubMed

Amano, M; Yatsuki, K; Umeda, G

1987-09-01

To clarify the relationship between the cervicobrachial disorders in the school-lunch female cooks and number of lunch, 15 elementary school-lunch cooks of O town whose quorum were observed by the standard of the Ministry of Education, Science and Culture and 19 cooks of M town whose quorum was one more than the standard were examined medically and their work conditions were also investigated. Results were as follows: 1) There were significantly (p less than 0.01) more cooks medically classified as "Normal (A)" in M town than in O town. Conversely, cooks classified as "Need therapy (C)" were more numerous in O town (p less than 0.01) than in M town (p less than 0.05). 2) In clinical findings prevalence rates such as median nerve extension test, cinesalgia in the neck, tenderness (flexor tendon of the lst finger of the hand, trapezius muscle, rhomboid muscle, teres minor muscle, brachioradial muscle) were higher in O town cooks than in M town cooks significantly (p less than 0.05). Complaint rates of the subjective symptoms or activities of daily living such as "pain in the neck," "pain in the arms," "want to lie down at free time" were higher in O town cooks than those in M town cooks significantly (p less than 0.05). 3) Average numbers of lunch and classes per cook were 137 lunch and 3.3 classes for O town cooks, and 114 and 2.9 for M town cooks, respectively. The average number of lunch of two towns were significantly different (p less than 0.05).(ABSTRACT TRUNCATED AT 400 WORDS)

Renewal: New Aspects of Acceleration and Transport of Solar Energetic Particles (SEPs) from the Sun to the Earth

DTIC Science & Technology

2014-10-31

Hole .......................................................4 2. SOHO EIT Image with Coronal Holes and FPA Vector...Diagram of CME Deflection by a Coronal Hole Figure 2: SOHO EIT Image with Coronal Holes and FPA Vector Approved for public release; distribution

77 FR 31041 - Draft Standards and Best Practices for Interaction Between Medical Examiner/Coroner and Organ and...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-05-24

... Best Practices for Interaction Between Medical Examiner/Coroner and Organ and Tissue Procurement... titled ``Organ and Tissue Procurement Committee Standards and Best Practices for Interaction Between Medical Examiner/Coroner Offices and Organ Tissue Procurement Organizations'' from May 12, 2012, to June...

Coronal Hole Faces Earth

NASA Image and Video Library

2017-08-14

A substantial coronal hole rotated into a position where it is facing Earth (Aug. 9-11, 2017). Coronal holes are areas of open magnetic field that spew out charged particles as solar wind that spreads into space. If that solar wind interacts with our own magnetosphere it can generate aurora. In this view of the sun in extreme ultraviolet light, the coronal hole appears as the dark stretch near the center of the sun. It was the most distinctive feature on the sun over the past week. Movies are available at https://photojournal.jpl.nasa.gov/catalog/PIA21874

Returning Coronal Hole

NASA Image and Video Library

2017-02-06

A substantial coronal hole rotated across the face of the sun this past week and is again streaming solar wind towards Earth (Jan. 30 - Feb. 2, 2017). This same coronal hole was facing Earth about a month ago and has rotated into a similar position again. Coronal holes are areas of open magnetic field from which solar wind particles stream into space. In this wavelength of extreme ultraviolet light it appears as a dark area near the center and lower portion of the sun. Movies are available at http://photojournal.jpl.nasa.gov/catalog/PIA11177

A Triumvirate: Three Coronal Holes

NASA Image and Video Library

2015-09-10

Three substantial coronal holes rotated across the face of the Sun the week of Sept. 8-10, 2015 as seen by NASA Solar Dynamics Observatory. Coronal holes are areas where the Sun magnetic field is open and a source of streaming solar wind. They appear darker in extreme ultraviolet light because there is less material in the hole areas being imaged in this specific wavelength of light. It is a little unusual to have three coronal holes at the same time, but neither is it a rare occurrence. http://photojournal.jpl.nasa.gov/catalog/PIA19950

Coronal Hole Coming Around

NASA Image and Video Library

2016-12-06

A substantial coronal hole began to rotate into view over the past few days (Dec. 1-2, 2016). Coronal holes are magnetically open areas of the sun's magnetic field structure that spew streams of high speed solar wind into space. In about a week or so that coronal hole might send streams of particles in the direction of Earth. Often times these streams can interact with Earth's magnetosphere and generate aurora. The images were taken in a wavelength of extreme ultraviolet light. Movies are available at http://photojournal.jpl.nasa.gov/catalog/PIA21208

Coronal Field Opens at Lower Height During the Solar Cycles 22 and 23 Minimum Periods: IMF Comparison Suggests the Source Surface Should Be Lowered (Postprint)

DTIC Science & Technology

2012-03-01

understood simply from differences in the areas of the coronal holes , as opposed to differences in the surface fields within them. In this study, we...invoke smaller source surface radii in the potential-field source-surface (PFSS) model to construct a consistent picture of the observed coronal holes ...that the values of ≈1.9 R and ≈1.8 R for the cycles 22 and 23 minimum periods, respectively, produce the best results. The larger coronal holes

Unilateral coronal craniosynostosis in Abraham Lincoln and his family.

PubMed

Fishman, Ronald S

2010-09-01

Premature closure of one coronal skull suture produces a characteristic arching or relative elevation of the superior orbital rim on the involved side. This sign is associated with facial asymmetry, and both signs are usually the most conspicuous features in patients with mild unilateral coronal craniosynostosis. Photographs suggest that at least 9 individuals over 5 generations of the Abraham Lincoln family had premature closure of 1 coronal suture. In 8 males, there was involvement of the left side; in 1 female, there was involvement of the right side.

Density and white light brightness in looplike coronal mass ejections - Temporal evolution

NASA Technical Reports Server (NTRS)

Steinolfson, R. S.; Hundhausen, A. J.

1988-01-01

Three ambient coronal models suitable for studies of time-dependent phenomena were used to investigate the propagation of coronal mass ejections initiated in each atmosphere by an identical energy source. These models included those of a static corona with a dipole magnetic field, developed by Dryer et al. (1979); a steady polytropic corona with an equatorial coronal streamer, developed by Steinolfson et al. (1982); and Steinolfson's (1988) model of heated corona with an equatorial coronal streamer. The results indicated that the first model does not adequately represent the general characteristics of observed looplike mass ejections, and the second model simulated only some of the observed features. Only the third model, which included a heating term and a streamer, was found to yield accurate simulation of the mess ejection observations.

Coronal magnetic fields and the solar wind

NASA Technical Reports Server (NTRS)

Newkirk, G., Jr.

1972-01-01

Current information is presented on coronal magnetic fields as they bear on problems of the solar wind. Both steady state fields and coronal transient events are considered. A brief critique is given of the methods of calculating coronal magnetic fields including the potential (current free) models, exact solutions for the solar wind and field interaction, and source surface models. These solutions are compared with the meager quantitative observations which are available at this time. Qualitative comparisons between the shapes of calculated magnetic field lines and the forms visible in the solar corona at several recent eclipses are displayed. These suggest that: (1) coronal streamers develop above extended magnetic arcades which connect unipolar regions of opposite polarity; and (2) loops, arches, and rays in the corona correspond to preferentially filled magnetic tubes in the approximately potential field.

Flux-tube divergence, coronal heating, and the solar wind

NASA Technical Reports Server (NTRS)

Wang, Y.-M.

1993-01-01

Using model calculations based on a self-consistent treatment of the coronal energy balance, we show how the magnetic flux-tube divergence rate controls the coronal temperature and the properties of the solar wind. For a fixed input of mechanical and Alfven-wave energy at the coronal base, we find that as the divergence rate increases, the maximum coronal temperature decreases but the mass flux leaving the sun gradually increases. As a result, the asymptotic wind speed decreases with increasing expansion factor near the sun, in agreement with empirical studies. As noted earlier by Withbroe, the calculated mass flux at the sun is remarkably insensitive to parameter variations; when combined with magnetohydrodynamic considerations, this self-regulatory property of the model explains the observed constancy of the mass flux at earth.

Simultaneous Solar Maximum Mission (SMM) and very large array observations of solar active regions

NASA Technical Reports Server (NTRS)

Lang, K. R.

1986-01-01

The research deals mainly with Very Large Array and Solar Maximum Mission observations of the ubiquitous coronal loops that dominate the structure of the low corona. As illustrated, the observations of thermal cyclotron lines at microwave wavelengths provide a powerful new method of accurately specifying the coronal magnetic field strength. Processes are delineated that trigger solar eruptions from coronal loops, including preburst heating and the magnetic interaction of coronal loops. Evidence for coherent burst mechanisms is provided for both the Sun and nearby stars, while other observations suggest the presence of currents that may amplify the coronal magnetic field to unexpectedly high levels. The existence is reported of a new class of compact, variable moving sources in regions of apparently weak photospheric field.

Does Tibial Slope Affect Perception of Coronal Alignment on a Standing Anteroposterior Radiograph?

PubMed

Schwartz, Adam J; Ravi, Bheeshma; Kransdorf, Mark J; Clarke, Henry D

2017-07-01

A standing anteroposterior (AP) radiograph is commonly used to evaluate coronal alignment following total knee arthroplasty (TKA). The impact of coronal alignment on TKA outcomes is controversial, perhaps due to variability in imaging and/or measurement technique. We sought to quantify the effect of image rotation and tibial slope on coronal alignment. Using a standard extramedullary tibial alignment guide, 3 cadaver legs were cut to accept a tibial tray at 0°, 3°, and 7° of slope. A computed tomography scan of the entire tibia was obtained for each specimen to confirm neutral coronal alignment. Images were then obtained at progressive 10° intervals of internal and external rotation up to 40° maximum in each direction. Images were then randomized and 5 blinded TKA surgeons were asked to determine coronal alignment. Continuous data values were transformed to categorical data (neutral [0], valgus [L], and varus [R]). Each 10° interval of external rotation of a 7° sloped tibial cut (or relative internal rotation of a tibial component viewed in the AP plane) resulted in perception of an additional 0.75° of varus. The slope of the proximal tibia bone cut should be taken into account when measuring coronal alignment on a standing AP radiograph. Copyright © 2017 Elsevier Inc. All rights reserved.

Factors influencing coroners' verdicts: an analysis of verdicts given in 12 coroners’ districts to researcher-defined suicides in England in 2005

PubMed Central

Palmer, Bret S.; Bennewith, Olive; Simkin, Sue; Cooper, Jayne; Hawton, Keith; Kapur, Nav; Gunnell, David

2015-01-01

Abstract Background To investigate the variation between coroners in the verdicts given to deaths thought by researchers to be probable suicides and analyse factors associated with the coroners’ verdict. Methods Data were collected from 12 English coroner districts on all deaths in 2005 given a suicide, open, accidental or narrative verdict where suicide was considered a possibility. The data were reviewed by three experienced suicide researchers. Regression models were used to investigate factors associated with the coroners’ verdict. Results The researchers classified 593 deaths as suicide, of which 385 (65.4%) received a suicide verdict from the coroner. There was marked variation between coroner districts in the verdicts they gave. The suicide method was associated strongly with the coroners’ verdict; deaths from poisoning and drowning were the least likely to be given suicide verdicts. The other factors strongly associated with a coroner's verdict of suicide were: whether a note was left, age over 60 years and being married or widowed compared with being single. Conclusion Coroners vary considerably in the verdicts they give to individuals who probably died by suicide. This may compromise the usefulness of suicide statistics for assessing area differences in rates for public health surveillance. PMID:24722626

STEREO OBSERVATIONS OF FAST MAGNETOSONIC WAVES IN THE EXTENDED SOLAR CORONA ASSOCIATED WITH EIT/EUV WAVES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kwon, Ryun-Young; Ofman, Leon; Kramar, Maxim

2013-03-20

We report white-light observations of a fast magnetosonic wave associated with a coronal mass ejection observed by STEREO/SECCHI/COR1 inner coronagraphs on 2011 August 4. The wave front is observed in the form of density compression passing through various coronal regions such as quiet/active corona, coronal holes, and streamers. Together with measured electron densities determined with STEREO COR1 and Extreme UltraViolet Imager (EUVI) data, we use our kinematic measurements of the wave front to calculate coronal magnetic fields and find that the measured speeds are consistent with characteristic fast magnetosonic speeds in the corona. In addition, the wave front turns outmore » to be the upper coronal counterpart of the EIT wave observed by STEREO EUVI traveling against the solar coronal disk; moreover, stationary fronts of the EIT wave are found to be located at the footpoints of deflected streamers and boundaries of coronal holes, after the wave front in the upper solar corona passes through open magnetic field lines in the streamers. Our findings suggest that the observed EIT wave should be in fact a fast magnetosonic shock/wave traveling in the inhomogeneous solar corona, as part of the fast magnetosonic wave propagating in the extended solar corona.« less

A two-year prospective study of coronally positioned flap with or without acellular dermal matrix graft.

PubMed

de Queiroz Côrtes, Antonieta; Sallum, Antonio Wilson; Casati, Marcio Z; Nociti, Francisco H; Sallum, Enilson A

2006-09-01

Evaluation of the treatment of gingival recessions with coronally positioned flap with or without acellular dermal matrix allograft (ADM) after a period of 24 months. Thirteen patients with bilateral gingival recessions were included. The defects were randomly assigned to one of the treatments: coronally positioned flap plus ADM or coronally positioned flap alone. The clinical measurements were taken before the surgeries and after 6, 12 and 24 months. At baseline, the mean values for recession height were 3.46 and 3.58 mm for the defects treated with and without the graft, respectively (p>0.05). No significant differences between the groups were observed after 6 and 12 months in this parameter. However, after 24 months, the group treated with coronally positioned flap alone showed a greater recession height when compared with the group treated with ADM (1.62 and 1.15 mm, respectively--p<0.05). A significant increase in the thickness of keratinized tissue was observed in the group treated with ADM as compared with coronally positioned flap alone (p<0.05). ADM may reduce the residual gingival recession observed after 24 months in defects treated with coronally positioned flap. In addition, a greater gingival thickness may be achieved when the graft is used.

Neutral-Line Magnetic Shear and Enhanced Coronal Heating in Solar Active Regions

NASA Technical Reports Server (NTRS)

Falconer, D. A.; Moore, R. L.; Porter, J. G.; Gary, G. A.; Shimizu, T.

1997-01-01

By examining the magnetic structure at sites in the bright coronal interiors of active regions that are not flaring but exhibit persistent strong coronal heating, we establish some new characteristics of the magnetic origins of this heating. We have examined the magnetic structure of these sites in five active regions, each of which was well observed by both the Yohkoh SXT and the Marshall Space Flight Center Vector Magnetograph and showed strong shear in its magnetic field along part of at least one neutral line (polarity inversion). Thus, we can assess whether this form of nonpotential field structure in active regions is a characteristic of the enhanced coronal heating and vice versa. From 27 orbits' worth of Yohkoh SXT images of the five active regions, we have obtained a sample of 94 persistently bright coronal features (bright in all images from a given orbit), 40 long (greater than or approximately equals 20,000 km) neutral-line segments having strong magnetic shear throughout (shear angle greater than 45 deg), and 39 long neutral-line segments having weak magnetic shear throughout (shear angle less than 45 deg). From this sample, we find that: (1) all of our persistently bright coronal features are rooted in magnetic fields that are stronger than 150 G; (2) nearly all (95%) of these enhanced coronal features are rooted near neutral lines (closer than 10,000 km); (3) a great majority (80%) of the bright features are rooted near strong-shear portions of neutral lines; (4) a great majority (85%) of long strong-shear segments of neutral lines have persistently bright coronal features rooted near them; (5) a large minority (40%) of long weak-shear segments of neutral lines have persistently bright coronal features rooted near them; and (6) the brightness of a persistently bright Coronal feature often changes greatly over a few hours. From these results, we conclude that most persistent enhanced heating of coronal loops in active regions: (1) requires the presence of a polarity inversion in the magnetic field near at least one of the loop footpoints; (2) is greatly aided by the presence of strong shear in the core magnetic field along that neutral line; and (3) is controlled by some variable process that acts in this magnetic environment. We infer that this variable process is low-lying reconnection accompanying flux cancellation.

Coronal Heating and the Magnetic Flux Content of the Network

NASA Technical Reports Server (NTRS)

Falconer, D. A.; Moore, R. L.; Porter, J. G.; Hathaway, D. H.; Whitaker, Ann F. (Technical Monitor)

2001-01-01

Previously, from analysis of SOHO/EIT coronal images in combination with Kitt Peak magnetograms (Falconer et al 1998, ApJ, 501, 386-396), we found that the quiet corona is the sum of two components: the e-scale corona and the coronal network. The large-scale corona consists of all coronal-temperature (T approx. 10(exp 6) K) structures larger than supergranules (>approx.30,000 km). The coronal network (1) consists of all coronal-temperature structures smaller than supergranules, (2) is rooted in and loosely traces the photospheric magnetic network, (3) has its brightest features seated on polarity dividing fines (neutral lines) in the network magnetic flux, and (4) produces only about 5% of the total coronal emission in quiet regions. The heating of the coronal network is apparently magnetic in origin. Here, from analysis of EIT coronal images of quiet regions in combination with magnetograms of the same quiet regions from SOHO/MDI and from Kitt Peak, we examine the other 95% of the quiet corona and its relation to the underlying magnetic network. We find: (1) Dividing the large-scale corona into its bright and dim halves divides the area into bright "continents" and dark "oceans" having spans of 2-4 supergranules. (2) These patterns are also present in the photospheric magnetograms: the network is stronger under the bright half and weaker under the dim half. (3) The radiation from the large-scale corona increases roughly as the cube root of the magnetic flux content of the underlying magnetic network. In contrast, Fisher et A (1998, ApJ, 508, 985-998) found that the coronal radiation from an active region increases roughly linearly with the magnetic flux content of the active region. We assume, as is widely held, that nearly all of the large-scale corona is magnetically rooted in the network. Our results, together with the result of Fisher et al (1999), suggest that either the coronal heating in quiet regions has a large non-magnetic component, or, if the heating is predominantly produced via the magnetic field, the mechanism is significantly different than in active regions. This work is funded by NASA's Office of Space Science through the Solar Physics Supporting Research and Technology Program and the Sun-Earth Connection Guest Investigator Program.

On Heating the Sun's Corona by Magnetic Explosions: Feasibility in Active Regions and prospects for Quiet Regions and Coronal Holes

NASA Technical Reports Server (NTRS)

Moore, Ronald L.; Falconer, D. A.; Porter, Jason G.; Suess, Steven T.

1999-01-01

We build a case for the persistent strong coronal heating in active regions and the pervasive quasi-steady heating of the corona in quiet regions and coronal holes being driven in basically the same way as the intense transient heating in solar flares: by explosions of sheared magnetic fields in the cores of initially closed bipoles. We begin by summarizing the observational case for exploding sheared core fields being the drivers of a wide variety of flare events, with and without coronal mass ejections. We conclude that the arrangement of an event's flare heating, whether there is a coronal mass ejection, and the time and place of the ejection relative to the flare heating are all largely determined by four elements of the form and action of the magnetic field: (1) the arrangement of the impacted, interacting bipoles participating in the event, (2) which of these bipoles are active (have sheared core fields that explode) and which are passive (are heated by injection from impacted active bipoles), (3) which core field explodes first, and (4) which core-field explosions are confined within the closed field of their bipoles and which ejectively open their bipoles. We then apply this magnetic-configuration framework for flare heating to the strong coronal heating observed by the Yohkoh Soft X-ray Telescope in an active region with strongly sheared core fields observed by the MSFC vector magnetograph. All of the strong coronal heating is in continually microflaring sheared core fields or in extended loops rooted against the active core fields. Thus, the strong heating occurs in field configurations consistent with the heating being driven by frequent core-field explosions that are smaller but similar to those in confined flares and flaring arches. From analysis of the thermal and magnetic energetics of two selected core-field microflares and a bright extended loop, we find that (1) it is energetically feasible for the sheared core fields to drive all of the coronal heating in the active region via a staccato of magnetic microexplosions, (2) the microflares at the feet of the extended loop behave as the flares at the feet of flaring arches in that more coronal heating is driven within the active bipole than in the extended loop, (3) the filling factor of the X-ray plasma in the core field microflares and in the extended loop is approximately 0.1, and (4) to release enough magnetic energy for a typical microflare (10^27 - 10^28 erg), a microflaring strand of sheared core field need expand and/or untwist by only a few percent at most. Finally, we point out that (1) the field configurations for strong coronal heating in our example active region (i.e., neutral-line core fields, many embedded in the feet of extended loops) are present in abundance in the magnetic network in quiet regions and coronal holes, and (2) it is known that many network bipoles do microflare and that many produce detectable coronal heating. We therefore propose that exploding sheared core fields are the drivers of most of the heating and dynamics of the solar atmosphere, ranging from the largest and most powerful coronal mass ejections and flares, to the vigorous microflaring and coronal heating in active regions, to the multitude of fine-scale explosive events in the magnetic network. The low-lysing exploding core fields in the network drive microflares, spicules, global coronal heating, and ,consequently, the solar wind.

An array effect of wave energy farm buoys

NASA Astrophysics Data System (ADS)

Kweon, Hyuck-Min; Lee, Jung-Lyul

2012-12-01

An ocean buoy energy farm is considered for Green energy generation and delivery to small towns along the Korean coast. The present studypresents that the floating buoy-type energy farm appears to be sufficiently feasible fortrapping more energy compared to afixed cylinder duck array. It is also seen from the numerical resultsthat the resonated waves between spaced buoys are further trapped by floating buoy motion.Our numerical study is analyzed by a plane-wave approximation, in which evanescent mode effects are included in a modified mild-slope equation based on the scattering characteristics for a single buoy.

Renewal of a Small Town in Poland Based on Example of Ustka

NASA Astrophysics Data System (ADS)

Poczobut, Joanna

2017-10-01

Ustka is a historical seaside town, port and health resort, a town of many possibilities. In this tourist town the old urban arrangement and many historic objects are preserved. Despite such potential, the town struggles with various problems, as do many small towns in the north of Poland. In 2003 works on a revitalization programme began (it has been implemented since 2005). The next stage was a programme which started in 2011. At present Ustka prepares for the next revitalization plan-a “District Revitalization Programme for 2016 - 2022”. The article describes: the situation at different stages of town development related to previously carried out revitalization programmes and the prospects for its further prosperity.

Going to Town: Where Is the Nearest Steakhouse?

ERIC Educational Resources Information Center

Robinson, Michael

2013-01-01

Growing up in Loretto, Tennessee, population 1,700, people called it "going to town" when they went to any city big enough to have a McDonald's, Walmart, or a movie theater. If someone is not from a small town, they may not know what type of economic activities a small town can support. Will the town have a police department? Will there…

Aerobic granulation in a modified oxidation ditch with an adjustable volume intraclarifier.

PubMed

Li, Jun; Cai, Ang; Wang, Miao; Ding, Libin; Ni, Yongjiong

2014-04-01

A modified oxidation ditch (MOD) with an adjustable volume intraclarifier was proposed and used to achieve aerobic sludge granulation in continuous flow process. This MOD with working volume of 60L treated onsite wastewater from a town. Excellent aerobic granules with mean diameter of 600μm and sludge volume index (SVI) of 44mL/g were obtained in 120day. Bacterial community analysis revealed that most species from seed sludge were preserved in both MOD and granule SBR (G-SBR) except bacteria (Bacteroidetes) might be easily washed out during granulation. Some different bacterial communities were found in sludges from sequencing batch and continuous flow reactors. Presence of metal ions and inorganics in raw wastewater had positive effect on granule formation, but an adjustable volume intraclarifier for controlling selection pressure and deleting return sludge pump played a key role in aerobic sludge granulation. Copyright © 2014 Elsevier Ltd. All rights reserved.

Modified level II streambed-scour analysis for structure I-65-85-5527 crossing Sugar Creek in Johnson County, Indiana

USGS Publications Warehouse

Robinson, B.A.; Voelker, D.C.; Miller, R.L.

1997-01-01

Level II scour evaluations follow a process in which hydrologic, hydraulic, and sediment transport data are evaluated to calculate the depth of scour that may result when a given discharge is routed through a bridge opening. The results of the modified Level II analysis for structure 1-65-85-5527 on Interstate 65 crossing Sugar Creek in Johnson County, Indiana, are presented. The site is near the town of Amity in the southeastern part of Johnson County. Scour depths were computed with the Water Surface PROfile model, version V050196, which incorporates the scour-calculation procedures outlined in Hydraulic Engineering Circular No. 18. Total scour depths at the piers were approximately 26.8 feet for the modeled discharge of 26,000 cubic feet per second and approximately 30.8 feet for the modeled discharge of 34,100 cubic feet per second

Modified level II streambed-scour analysis for structure I-74-32-4946 crossing Sugar Creek in Montgomery County, Indiana

USGS Publications Warehouse

Miller, R.L.; Robinson, B.A.; Voelker, D.C.

1997-01-01

Level II scour evaluations follow a process in which hydrologic, hydraulic, and sedient-transport data are evaluated to calculate the depth of scour that may result when given discharge is routed through a bridge opening. The results of the modified Levell II analysis for structure I-74-32-4946 on Interstate 74 crossing Sugar Creek in Montgomery County, Indiana are presented. The site is near the town of Crawfordsville in the central part of Montgomery County. Scour depths were computed with the Water Surface PROfile model, version V050196, which incorporates the scour-calculation procedures outlined in Hydraulic Engineering Circular No. 18. Total scour depths at the piers were approximately 13.0 feet for the modeled discharge of 3,000  cubic feet per second and approximately 15.1 feet for the modeled discharge of 41,900 cubic feet per second.

Modified Mercalli Intensities (MMI) for some earthquakes in eastern North America (ENA) and empirical MMI site corrections for towns in ENA

USGS Publications Warehouse

Bakun, W.H.; Johnston, A.C.; Hopper, M.G.

2002-01-01

Modified Mercalli Intensity (MMI) assignments for earthquakes in eastern North America (ENA) were used by Bakun et al. (submitted) to develop a model for eastern North America for estimating the location and moment magnitude M of earthquakes from MMI observations. MMI assignments for most of the earthquakes considered by Bakun et al. (submitted) are published. MMI assignments for 6 other earthquakes used by Bakun et al. (submitted) are listed in this report: November 18, 1755 near Cape Ann, Massachusetts; January 5, 1843 near Marked Tree, Arkansas; October 31, 1895 in southern Illinois; November 18, 1929 on the Grand Banks, Newfoundland; September 26, 1990 in southeast Missouri; and May 4, 1991 near Risco, Missouri. MMI empirical site corrections developed and used by Bakun et al. (submitted) are also listed in this report.

RadTown USA: Basic Information

MedlinePlus

... Burbs Countryside Waterfront Downtown Did you know? RadTown Games Educational Materials Bring RadTown into the classroom with ... Waterfront Downtown Educational Materials RadTown A to Z Games Link to Us Glossary Subscribe to Listserv News ...

40 CFR 81.90 - Androscoggin Valley Interstate Air Quality Control Region.

Code of Federal Regulations, 2012 CFR

2012-07-01

... Androscoggin Valley Interstate Air Quality Control Region (Maine-New Hampshire) consists of the territorial... New Hampshire: Cass County. ..., New Sharron Town, New Vineyard Town, Perkins Township, Phillips Town, Salem Township, Strong Town...

40 CFR 81.90 - Androscoggin Valley Interstate Air Quality Control Region.

Code of Federal Regulations, 2013 CFR

2013-07-01

... Androscoggin Valley Interstate Air Quality Control Region (Maine-New Hampshire) consists of the territorial... New Hampshire: Cass County. ..., New Sharron Town, New Vineyard Town, Perkins Township, Phillips Town, Salem Township, Strong Town...

40 CFR 81.90 - Androscoggin Valley Interstate Air Quality Control Region.

Code of Federal Regulations, 2014 CFR

2014-07-01

... Androscoggin Valley Interstate Air Quality Control Region (Maine-New Hampshire) consists of the territorial... New Hampshire: Cass County. ..., New Sharron Town, New Vineyard Town, Perkins Township, Phillips Town, Salem Township, Strong Town...

Suppression of heating of coronal loops rooted in opposite polarity sunspot umbrae

NASA Astrophysics Data System (ADS)

Tiwari, Sanjiv K.; Thalmann, Julia K.; Moore, Ronald L.; Panesar, Navdeep; Winebarger, Amy R.

2016-05-01

EUV observations of active region (AR) coronae reveal the presence of loops at different temperatures. To understand the mechanisms that result in hotter or cooler loops, we study a typical bipolar AR, near solar disk center, which has moderate overall magnetic twist and at least one fully developed sunspot of each polarity. From AIA 193 and 94 A images we identify many clearly discernible coronal loops that connect plage or a sunspot of one polarity to an opposite-polarity plage region. The AIA 94 A images show dim regions in the umbrae of the spots. To see which coronal loops are rooted in a dim umbral area, we performed a non-linear force-free field (NLFFF) modeling using photospheric vector magnetic field measurements obtained with the HMI onboard SDO. After validation of the NLFFF model by comparison of calculated model field lines and observed loops in AIA 193 and 94, we specify the photospheric roots of the model field lines. The model field then shows the coronal magnetic loops that arch from the dim umbral areas of the opposite polarity sunspots. Because these coronal loops are not visible in any of the coronal EUV and X-ray images of the AR, we conclude they are the coolest loops in the AR. This result suggests that the loops connecting opposite polarity umbrae are the least heated because the field in umbrae is so strong that the convective braiding of the field is strongly suppressed.We hypothesize that the convective freedom at the feet of a coronal loop, together with the strength of the field in the body of the loop, determines the strength of the heating. In particular, we expect the hottest coronal loops to have one foot in an umbra and the other foot in opposite-polarity penumbra or plage (coronal moss), the areas of strong field in which convection is not as strongly suppressed as in umbra. Many transient, outstandingly bright, loops in the AIA 94 movie of the AR do have this expected rooting pattern. We will also present another example of AR in which we find a similar rooting pattern of coronal loops.

Spontaneous correction of coronal imbalance after selective thoracolumbar-lumbar fusion in patients with Lenke-5C adolescent idiopathic scoliosis.

PubMed

Hwang, Chang Ju; Lee, Choon Sung; Kim, Hyojune; Lee, Dong-Ho; Cho, Jae Hwan

2018-03-22

Coronal imbalance is a complication of corrective surgeries in adolescent idiopathic scoliosis (AIS). However, few studies about immediate coronal decompensation in Lenke-5C curves have reported its incidence, prognosis, and related factors. To evaluate the development of coronal imbalance after selective thoracolumbar-lumbar (TL/L) fusion (SLF) in Lenke-5C AIS, and to reveal related factors. Retrospective comparative study. This study included 50 consecutive patients with Lenke-5C AIS who underwent SLF at a single center. Whole-spine anteroposterior and lateral radiographs were used to measure radiological parameters. Patients were divided into two groups according to the presence or absence of coronal imbalance (distance between C7 plumb line and central sacral vertical line >2 cm) in the early (1 month) postoperative period. Various radiological parameters were statistically compared between groups. Of the patients, 28% (14 of 50) showed coronal imbalance in the early postoperative period; however, most of them (13 of 14) showed spontaneous correction during follow-up. The development of coronal imbalance was related to less flexibility of the TL/L curve (51.3% vs. 52.6%, p=.040), greater T10-L2 kyphosis (11.7° vs. 6.4°, p=.034), and greater distal junctional angle (6.0° vs. 3.7°, p=.025) in preoperative radiographs. Lowermost instrumented vertebra (LIV) tilt was greater in the decompensation [+] group in the early postoperative period (8.8° vs. 4.4°, p=.009). However, this difference disappeared in final follow-up with the decrease of LIV tilt in the decompensation [+] group. Less flexibility of the TL/L curve, greater TL kyphosis, and greater distal junctional angle preoperatively were predictive factors for immediate coronal imbalance in Lenke-5C curves. Although coronal imbalance was frequently detected in the early postoperative period after SLF, it was mostly corrected spontaneously with a decrease of LIV tilt. Thus, SLF for Lenke-5C curves can be a good option regardless of the possible coronal imbalance in the early postoperative period. Copyright © 2018 Elsevier Inc. All rights reserved.

Geometry of solar coronal rays

NASA Astrophysics Data System (ADS)

Filippov, B. P.; Martsenyuk, O. V.; Platov, Yu. V.; Den, O. E.

2016-02-01

Coronal helmet streamers are the most prominent large-scale elements of the solar corona observed in white light during total solar eclipses. The base of the streamer is an arcade of loops located above a global polarity inversion line. At an altitude of 1-2 solar radii above the limb, the apices of the arches sharpen, forming cusp structures, above which narrow coronal rays are observed. Lyot coronagraphs, especially those on-board spacecrafts flying beyond the Earth's atmosphere, enable us to observe the corona continuously and at large distances. At distances of several solar radii, the streamers take the form of fairly narrow spokes that diverge radially from the Sun. This radial direction displays a continuous expansion of the corona into the surrounding space, and the formation of the solar wind. However, the solar magnetic field and solar rotation complicate the situation. The rotation curves radial streams into spiral ones, similar to water streams flowing from rotating tubes. The influence of the magnetic field is more complex and multifarious. A thorough study of coronal ray geometries shows that rays are frequently not radial and not straight. Coronal streamers frequently display a curvature whose direction in the meridional plane depends on the phase of the solar cycle. It is evident that this curvature is related to the geometry of the global solar magnetic field, which depends on the cycle phase. Equatorward deviations of coronal streamers at solar minima and poleward deviations at solar maxima can be interpreted as the effects of changes in the general topology of the global solar magnetic field. There are sporadic temporal changes in the coronal rays shape caused by remote coronal mass ejections (CMEs) propagating through the corona. This is also a manifestation of the influence of the magnetic field on plasma flows. The motion of a large-scale flux rope associated with a CME away from the Sun creates changes in the structure of surrounding field lines, which are similar to the kink propagation along coronal rays. Careful analysis of these events could give us valuable information about the coronal plasma.

Coronal Magnetography of Solar Active Regions Using Coordinated SOHO/CDS and VLA Observations

NASA Technical Reports Server (NTRS)

Brosius, Jeffrey W.

1999-01-01

The purpose of this project is to apply the coronal magnetographic technique to SOHO (Solar Heliospheric Observatory) /CDS (Coronal Diagnostic Spectrometer) EUV (Extreme Ultraviolet Radiation) and coordinated VLA microwave observations of solar active regions to derive the strength and structure of the coronal magnetic field. A CDS observing plan was developed for obtaining spectra needed to derive active region differential emission measures (DEMs) required for coronal magnetography. VLA observations were proposed and obtained. SOHO JOP 100 was developed, tested, approved, and implemented to obtain coordinated CDS (Coronal Diagnostic Spectrometer)/EIT (Ultraviolet Imaging Telescope)/ VLA (Very Large Array)/ TRACE (Transition Region and Coronal Explorer)/ SXT (Solar X Ray Telescope) observations of active regions on April 12, May 9, May 13, and May 23. Analysis of all four data sets began, with heaviest concentration on COS data. It is found that 200-pixel (14 A in NIS1) wavelength windows are appropriate for extracting broadened Gaussian line profile fit parameters for lines including Fe XIV at 334.2, Fe XVI at 335.4, Fe XVI at 360.8, and Mg IX at 368.1 over the 4 arcmin by 4 arcmin CDS field of view. Extensive efforts were focused on learning and applying were focused on learning and applying CDS software, and including it in new IDL procedures to carry out calculations relating to coronal magnetography. An important step is to extract Gaussian profile fits to all the lines needed to derive the DEM in each spatial pixel of any given active region. The standard CDS absolute intensity calibration software was applied to derived intensity images, revealing that ratios between density-insensitive lines like Fe XVI 360.8/335.4 yield good agreement with theory. However, the resulting absolute intensities of those lines are very high, indicating that revisions to the CDS absolute intensity calibrations remain to be included in the CDS software, an essential step to deriving reliable coronal magnetograms. With lessons learned and high quality data obtained during the past year, coronal magnetography will be successfully pursued under my new SOHO GI program.

Off The Scale - Expansion or Development? A Small Town within a Metropolitan Zone as an Alternative Place of Residence

NASA Astrophysics Data System (ADS)

Wójtowicz-Wróbel, Agnieszka

2017-10-01

The goal of this paper is to point out the types of spatial changes that the small towns located in Krakow’s range of influence are currently undergoing, as well as what are the consequences of the various types of changes in these towns. The author asks the question whether the current changes seen in small towns that are under the influence of Krakow can be described as sustainable development - at the basis of which is the increasing of the quality of the functional and spatial structure of a town while preserving its qualities and character - or, on the contrary, that it is more appropriate to describe the changes in the spatial structure of towns as an expansion, which is related only to an increase in their surface area or an increase in the density of their built environment? An attempt has also been made to determine the cause of these changes. An analysis of a set of towns in terms of their accessibility in relation to Krakow, as well as the demographic changes in towns in recent years, has been carried out. This research was useful in determining the dynamic of urban changes or their stagnation. Afterwards, groups of towns with varying degrees of transformation (towns that have been intensively transformed, towns with a balanced degree of spatial changes and towns which remain on the side-lines) were established. In addition, various forms of changes were defined - ranging from cities which register an increase in attractiveness and the changes that it brings while preserving their qualities in accordance with the principles of sustainable development, to settlements which are losing their small-town character as a result of intensive change, at the same time undergoing unification both in terms of space and form of use. From among the groups of towns, example which most fully illustrate the varying degrees and character of the changes of small towns in the area of Krakow has been selected. Based on the research that has been conducted, we can state that small towns in the vicinity of Krakow are undergoing intensive changes and are an attractive alternative in terms of serving as a place of residence, for instance in comparison to the suburban zone of Krakow. However, it is necessary to channel the changes in small towns in a manner that would take advantage of the opportunities for spatial, social and economic development on the one hand, while at the same time causing the intensive changes in those areas to not lead to the loss of their uniqueness, identity and small-town character, as well as the qualities of both a given town and its surroundings on the other. The research that had been performed and the conclusions that were drawn from it can serve as comparative material for other types of small towns and for metropolitan areas.

Deriving the Properties of Coronal Pressure Fronts in 3D: Application to the 2012 May 17 Ground Level Enhancement

NASA Astrophysics Data System (ADS)

Rouillard, A. P.; Plotnikov, I.; Pinto, R. F.; Tirole, M.; Lavarra, M.; Zucca, P.; Vainio, R.; Tylka, A. J.; Vourlidas, A.; De Rosa, M. L.; Linker, J.; Warmuth, A.; Mann, G.; Cohen, C. M. S.; Mewaldt, R. A.

2016-12-01

We study the link between an expanding coronal shock and the energetic particles measured near Earth during the ground level enhancement of 2012 May 17. We developed a new technique based on multipoint imaging to triangulate the three-dimensional (3D) expansion of the shock forming in the corona. It uses images from three vantage points by mapping the outermost extent of the coronal region perturbed by the pressure front. We derive for the first time the 3D velocity vector and the distribution of Mach numbers, M FM, of the entire front as a function of time. Our approach uses magnetic field reconstructions of the coronal field, full magnetohydrodynamic simulations and imaging inversion techniques. We find that the highest M FM values appear near the coronal neutral line within a few minutes of the coronal mass ejection onset; this neutral line is usually associated with the source of the heliospheric current and plasma sheet. We illustrate the variability of the shock speed, shock geometry, and Mach number along different modeled magnetic field lines. Despite the level of uncertainty in deriving the shock Mach numbers, all employed reconstruction techniques show that the release time of GeV particles occurs when the coronal shock becomes super-critical (M FM > 3). Combining in situ measurements with heliospheric imagery, we also demonstrate that magnetic connectivity between the accelerator (the coronal shock of 2012 May 17) and the near-Earth environment is established via a magnetic cloud that erupted from the same active region roughly five days earlier.

Combined metopic and unilateral coronal synostoses: a phenotypic conundrum.

PubMed

Sauerhammer, Tina M; Patel, Kamlesh; Oh, Albert K; Proctor, Mark R; Mulliken, John B; Rogers, Gary F

2014-03-01

Most types of craniosynostosis cause predictable changes in cranial shape. However, the phenotype of combined metopic and unilateral coronal synostoses is anomalous. The purpose of this observational study was to better clarify the clinical and radiographic features of this rare entity. A retrospective review of a craniofacial database was performed. Patients with combined metopic and unilateral coronal synostoses were included in this study. Data collected included demographic information, physical and radiographic findings, genetic evaluation, treatment, and operative outcomes. Of 687 patients treated between 1989 and 2010, only 3 patients had combined metopic and unilateral coronal synostoses. All patients were diagnosed through computed tomography on the first day of life. Phenotypic features included the following: (1) narrowed forehead with a prominent midline ridge, (2) severe bilateral brow retrusion with an acute indentation on the side of the patient coronal suture, (3) facial and nasal angulation similar to isolated unilateral coronal synostosis, and (4) anterior displacement of the ear on the fused side. In addition, the cranial vertex was deviated toward the side of the open coronal suture. Two patients had a head circumference below the 25th percentile; 2 of the 3 had a TWIST gene mutation consistent with Saethre-Chotzen syndrome. One patient was managed through fronto-orbital advancement and required a revision. The other 2 patients had early endoscopic release, followed by postoperative helmet therapy; one improved but still required open cranial remodeling. The other has near-normal phenotype, and no further surgery is planned. Combined metopic and unilateral coronal synostoses present a rare and unusual phenotype. Although early intervention improves the deformity, revisional procedures are usually required.

Magnetic Flux Cancellation as the Trigger Mechanism of Solar Coronal Jets

NASA Technical Reports Server (NTRS)

McGlasson, Riley A.; Panesar, Navdeep K.; Sterling, Alphonse C.; Moore, Ronald L.

2017-01-01

Coronal jets are narrow eruptions in the solar corona, and are often observed in extreme ultraviolet (EUV) and X-Ray images. They occur everywhere on the solar disk: in active regions, quiet regions, and coronal holes (Raouafi et al. 2016). Recent studies indicate that most coronal jets in quiet regions and coronal holes are driven by the eruption of a minifilament (Sterling et al. 2015), and that this eruption follows flux cancellation at the magnetic neutral line under the pre-eruption minifilament (Panesar et al. 2016). We confirm this picture for a large sample of jets in quiet regions and coronal holes using multithermal extreme ultraviolet (EUV) images from the Solar Dynamics Observatory (SDO)/Atmospheric Imaging Assembly (AIA) and line-of-sight magnetograms from the SDO/Helioseismic and Magnetic Imager (HMI). We report observations of 60 randomly selected jet eruptions. We have analyzed the magnetic cause of these eruptions and measured the base size and the duration of each jet using routines in SolarSoft IDL. By examining the evolutionary changes in the magnetic field before, during, and after jet eruption, we found that each of these jets resulted from minifilament eruption triggered by flux cancellation at the neutral line. In agreement with the above studies, we found our jets to have an average base diameter of 7600 +/- 2700 km and an average jet-growth duration of 9.0 +/- 3.6 minutes. These observations confirm that minifilament eruption is the driver and that magnetic flux cancellation is the primary trigger mechanism for nearly all coronal hole and quiet region coronal jet eruptions.

Decision-making in a death investigation: Emotion, families and the coroner.

PubMed

Tait, Gordon; Carpenter, Belinda; Quadrelli, Carol; Barnes, Michael

2016-03-01

The role of the coroner in common law countries such as Australia, England, Canada and New Zealand is to preside over death investigations where there is uncertainty as to the manner of death, a need to identify the deceased, a death of unknown cause, or a violent or unnatural death. The vast majority of these deaths are not suspicious and thus require coroners to engage with grieving families who have been thrust into a legal process through the misfortune of a loved one's sudden or unexpected death. In this research, 10 experienced coroners discussed how they negotiated the grief and trauma evident in a death investigation. In doing so, they articulated two distinct ways in which legal officers engaged with emotions, which are also evident in the literature. The first engages the script of judicial dispassion, articulating a hierarchical relationship between reason and emotion, while the second introduces an ethic of care via the principles of therapeutic jurisprudence, and thus offers a challenge to the role of emotion in the personae of the professional judicial officer. By using Hochschild's work on the sociology of emotions, this article discusses the various ways in which coroners manage the emotion of a death investigation through emotion work. While emotional distance may be an understandable response by coroners to the grief and trauma experienced by families and directed at cleaner coronial decision-making, the article concludes that coroners may be better served by offering emotions such as sympathy, consideration and compassion directly to the family in those situations where families are struggling to accept, or are resistant to, coroners' decisions.

TRIGGER MECHANISM OF SOLAR SUBFLARES IN A BRAIDED CORONAL MAGNETIC STRUCTURE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tiwari, Sanjiv K.; Alexander, Caroline E.; Winebarger, Amy R.

Fine-scale braiding of coronal magnetic loops by continuous footpoint motions may power coronal heating via nanoflares, which are spontaneous fine-scale bursts of internal reconnection. An initial nanoflare may trigger an avalanche of reconnection of the braids, making a microflare or larger subflare. In contrast to this internal triggering of subflares, we observe external triggering of subflares in a braided coronal magnetic field observed by the High-resolution Coronal Imager (Hi-C). We track the development of these subflares using 12 s cadence images acquired by SDO/AIA in 1600, 193, 94 Å, and registered magnetograms of SDO/HMI, over four hours centered on the Hi-Cmore » observing time. These data show numerous recurring small-scale brightenings in transition-region emission happening on polarity inversion lines where flux cancellation is occurring. We present in detail an example of an apparent burst of reconnection of two loops in the transition region under the braided coronal field which is appropriate for releasing a short reconnected loop downward and a longer reconnected loop upward. The short loop presumably submerges into the photosphere, participating in observed flux cancellation. A subflare in the overlying braided magnetic field is apparently triggered by the disturbance of the braided field by the reconnection-released upward loop. At least 10 subflares observed in this braided structure appear to be triggered this way. How common this external trigger mechanism for coronal subflares is in other active regions, and how important it is for coronal heating in general, remain to be seen.« less

IRIS Observations of Coronal Rain and Prominences: Return Flows of the Chromosphere-Corona Mass Cycle

NASA Astrophysics Data System (ADS)

Liu, Wei; Berger, Thomas; Antolin, Patrick; Schrijver, Karel

2014-06-01

It has recently been recognized that a mass cycle (e.g., Berger et al. 2011; McIntosh et al. 2012) between the hot, tenuous solar corona and the cool, dense chromosphere underneath it plays an important role in the mass budget and dynamic evolution of the solar atmosphere. Although the corona ultimately loses mass through the solar wind and coronal mass ejections, a fraction of its mass returns to the chromosphere in coronal rain, downflows of prominences, and other as-yet unidentified processes. We present here analysis of joint observations of IRIS, SDO/AIA, and Hinode/SOT of such phenomena. By utilizing the wide temperature coverage (logT: 4 - 7) provided by these instruments combined, we track the coronal cooling sequence (e.g., Schrijver 2001; Liu et al. 2012; Berger et al. 2012) leading to the formation of such material at transition region or chromospheric temperatures (logT: 4 - 5) in the million-degree corona. We compare the cooling times with those expected from the radiative cooling instability. We also measure the kinematics and densities of such downflows and infer their mass fluxes, which are compared to the upward mass fluxes into the corona, e.g., those associated with spicules and flux emergence. Special attention is paid to coronal rain formed near cusp-shaped portions of coronal loops, funnel-shaped prominences at dips of coronal loops, and their respective magnetic environments. With the information about where and when such catastrophic cooling events take place, we discuss the implications for the enigmatic coronal heating mechanisms (e.g., Antolin et al. 2010).

Coronal hole boundaries evolution at small scales. I. EIT 195 Å  and TRACE 171 Å view

NASA Astrophysics Data System (ADS)

Madjarska, M. S.; Wiegelmann, T.

2009-09-01

Aims: We aim to study the small-scale evolution at the boundaries of an equatorial coronal hole connected with a channel of open magnetic flux to the polar region and an “isolated” one in the extreme-ultraviolet spectral range. We determine the spatial and temporal scale of these changes. Methods: Imager data from TRACE in the Fe ix/x 171 Å passband and EIT on-board Solar and Heliospheric Observatory in the Fe xii 195 Å passband were analysed. Results: We found that small-scale loops known as bright points play an essential role in coronal hole boundary evolution at small scales. Their emergence and disappearance continuously expand or contract coronal holes. The changes appear to be random on a time scale comparable to the lifetime of the loops seen at these temperatures. No signature was found for a major energy release during the evolution of the loops. Conclusions: Although coronal holes seem to maintain their general shape during a few solar rotations, a closer look at their day-by-day and even hour-by-hour evolution demonstrates significant dynamics. The small-scale loops (10´´-40´´ and smaller) which are abundant along coronal hole boundaries contribute to the small-scale evolution of coronal holes. Continuous magnetic reconnection of the open magnetic field lines of the coronal hole and the closed field lines of the loops in the quiet Sun is more likely to take place. Movies are only available in electronic form at http://www.aanda.org

Hand and nickel-titanium root canal instrumentation performed by dental students: a micro-computed tomographic study.

PubMed

Peru, M; Peru, C; Mannocci, F; Sherriff, M; Buchanan, L S; Pitt Ford, T R

2006-02-01

The aim of this study was to evaluate root canals instrumented by dental students using the modified double-flared technique, nickel-titanium (NiTi) rotary System GT files and NiTi rotary ProTaper files by micro-computed tomography (MCT). A total of 36 root canals from 18 mesial roots of mandibular molar teeth were prepared; 12 canals were prepared with the modified double-flared technique, using K-flexofiles and Gates-Glidden burs; 12 canals were prepared using System GT and 12 using ProTaper rotary files. Each root was scanned using MCT preoperatively and postoperatively. At the coronal and mid-root sections, System GT and ProTaper files produced significantly less enlarged canal cross-sectional area, volume and perimeter than the modified double-flared technique (P < 0.05). In the mid-root sections there was significantly less thinning of the root structure towards the furcation with System GT and ProTaper (P < 0.05). The rotary techniques were both three times faster than the modified double-flared technique (P < 0.05). Qualitative evaluation of the preparations showed that both ProTaper and System GT were able to prepare root canals with little or no procedural error compared with the modified double-flared technique. Under the conditions of this study, inexperienced dental students were able to prepare curved root canals with rotary files with greater preservation of tooth structure, low risk of procedural errors and much quicker than with hand instruments.

Coronal Heating: Testing Models of Coronal Heating by Forward-Modeling the AIA Emission of the Ansample of Coronal Loops

NASA Astrophysics Data System (ADS)

Malanushenko, A. V.

2015-12-01

We present a systemic exploration of the properties of coronal heating, by forward-modeling the emission of the ensemble of 1D quasi-steady loops. This approximations were used in many theoretical models of the coronal heating. The latter is described in many such models in the form of power laws, relating heat flux through the photosphere or volumetric heating to the strength of the magnetic field and length of a given field line. We perform a large search in the parameter space of these power laws, amongst other variables, and compare the resulting emission of the active region to that observed by AIA. We use a recently developed magnetic field model which uses shapes of coronal loops to guide the magnetic model; the result closely resembles observed structures by design. We take advantage of this, by comparing, in individual sub-regions of the active region, the emission of the active region and its synthetic model. This study allows us to rule out many theoretical models and formulate predictions for the heating models to come.

Effects of non-Maxwellian electron velocity distribution functions and nonspherical geometry on minor ions in the solar wind

NASA Technical Reports Server (NTRS)

Burgi, A.

1987-01-01

A previous model has shown that in order to account for the charge state distribution in the low-speed solar wind, a high coronal temperature is necessary and that this temperature peak goes together with a peak of nx/np in the corona. In the present paper, one of the assumptions made previously, i.e., that coronal electrons are Maxwellian, is relaxed, and a much cooler model is presented, which could account for the same oxygen charge states in the solar wind due to the inclusion of non-Maxwellian electrons. Also, due to a different choice of the coronal magnetic field geometry, this model would show no enhancement of the coronal nx/np. Results of the two models are then compared, and observational tests to distinguish between the two scenarios are proposed: comparison of directly measured coronal Te to charge state measurements in the solar wind, determination of the coronal nx/np measurement of ion speeds in the acceleration region of the solar wind, and measurement of the frozen-in silicon charge state distribution.

The Magnetic Origins of Solar Activity

NASA Technical Reports Server (NTRS)

Antiochos, S. K.

2012-01-01

The defining physical property of the Sun's corona is that the magnetic field dominates the plasma. This property is the genesis for all solar activity ranging from quasi-steady coronal loops to the giant magnetic explosions observed as coronal mass ejections/eruptive flares. The coronal magnetic field is also the fundamental driver of all space weather; consequently, understanding the structure and dynamics of the field, especially its free energy, has long been a central objective in Heliophysics. The main obstacle to achieving this understanding has been the lack of accurate direct measurements of the coronal field. Most attempts to determine the magnetic free energy have relied on extrapolation of photospheric measurements, a notoriously unreliable procedure. In this presentation I will discuss what measurements of the coronal field would be most effective for understanding solar activity. Not surprisingly, the key process for driving solar activity is magnetic reconnection. I will discuss, therefore, how next-generation measurements of the coronal field will allow us to understand not only the origins of space weather, but also one of the most important fundamental processes in cosmic and laboratory plasmas.

Sources of magnetic fields in recurrent interplanetary streams

NASA Technical Reports Server (NTRS)

Burlaga, L. F.; Behannon, K. W.; Hansen, S. F.; Pneuman, G. W.; Feldman, W. C.

1978-01-01

The paper examines sources of magnetic fields in recurrent streams observed by the Imp 8 and Heos spacecraft at 1 AU and by Mariner 10 en route to Mercury between October 31, 1973 and February 9, 1974, during Carrington rotations 1607-1610. Although most fields and plasmas at 1 AU were related to coronal holes and the magnetic field lines were open in those holes, some of the magnetic fields and plasmas at 1 AU were related to open field line regions on the sun which were not associated with known coronal holes, indicating that open field lines may be more basic than coronal holes as sources of the solar wind. Magnetic field intensities in five equatorial coronal holes, certain photospheric magnetic fields, and the coronal footprints of the sector boundaries on the source surface are characterized.

REVIEWS OF TOPICAL PROBLEMS: Coronal magnetic loops

NASA Astrophysics Data System (ADS)

Zaitsev, Valerii V.; Stepanov, Alexander V.

2008-11-01

The goal of this review is to outline some new ideas in the physics of coronal magnetic loops, the fundamental structural elements of the atmospheres of the Sun and flaring stars, which are involved in phenomena such as stellar coronal heating, flare energy release, charged particle acceleration, and the modulation of optical, radio, and X-ray emissions. The Alfvén-Carlqvist view of a coronal loop as an equivalent electric circuit allows a good physical understanding of loop processes. Describing coronal loops as MHD-resonators explains various ways in which flaring emissions from the Sun and stars are modulated, whereas modeling them by magnetic mirror traps allows one to describe the dynamics and emission of high-energy particles. Based on these approaches, loop plasma and fast particle parameters are obtained and models for flare energy release and stellar corona heating are developed.

A CORONAL HOLE'S EFFECTS ON CORONAL MASS EJECTION SHOCK MORPHOLOGY IN THE INNER HELIOSPHERE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wood, B. E.; Wu, C.-C.; Howard, R. A.

2012-08-10

We use STEREO imagery to study the morphology of a shock driven by a fast coronal mass ejection (CME) launched from the Sun on 2011 March 7. The source region of the CME is located just to the east of a coronal hole. The CME ejecta is deflected away from the hole, in contrast with the shock, which readily expands into the fast outflow from the coronal hole. The result is a CME with ejecta not well centered within the shock surrounding it. The shock shape inferred from the imaging is compared with in situ data at 1 AU, wheremore » the shock is observed near Earth by the Wind spacecraft, and at STEREO-A. Shock normals computed from the in situ data are consistent with the shock morphology inferred from imaging.« less

Coronal structures deduced from photospheric magnetic field and He I lambda 10830 observations

NASA Technical Reports Server (NTRS)

Harvey, Karen L.

1995-01-01

The National Solar Observatory synoptic program provides an extensive and unique data base of high-resolution full-disk observations of the line-of-sight photospheric magnetic fields and of the He I lambda 10830 equivalent width. These data have been taken nearly daily for more than 21 years since 1974 and provide the opportunity to investigate the behavior of the magnetic fields in the photosphere and those inferred for the corona spanning on the time scales of a day to that of a solar cycle. The intensity of structures observed in He I lambda 10830 are strongly modulated by overlying coronal radiation; areas with low coronal emission are generally brighter in He I lambda 10830, while areas with high coronal emission are darker. For this reason, He I lambda 10830 was selected in the mid-1970's as way to identify and monitor coronal holes, magnetic fields with an open configuration, and the sources of high-speed solar wind streams. The He I lambda 10830 spectroheliograms also show a wide variety of other structures from small-scale, short-lived dark points (less than 30 arc-sec, hours) to the large-scale, long-lived two 'ribbon' flare events that follow the filament eruptions (1000 arc-sec, days). Such structures provide clues about the connections and changes in the large-scale coronal magnetic fields that are rooted in concentrations of magnetic network and active regions in the photosphere. In this paper, what observations of the photospheric magnetic field and He I lambda 10830 can tell us about the short- and long-term evolution of the coronal magnetic fields will be discussed, focussing on the quiet Sun and coronal holes. These data and what we infer from them will be compared with direct observations of the coronal structure from the Yohkoh Soft X-ray Telescope.

The Solar Wind from Pseudostreamers and their Environs: Opportunities for Observations with Parker Solar Probe and Solar Orbiter

NASA Astrophysics Data System (ADS)

Panasenco, O.; Velli, M.; Panasenco, A.; Lionello, R.

2017-12-01

The solar dynamo and photospheric convection lead to three main types of structures extending from the solar surface into the corona - active regions, solar filaments (prominences when observed at the limb) and coronal holes. These structures exist over a wide range of scales, and are interlinked with each other in evolution and dynamics. Active regions can form clusters of magnetic activity and the strongest overlie sunspots. In the decay of active regions, the boundaries separating opposite magnetic polarities (neutral lines) develop specific structures called filament channels above which filaments form. In the presence of flux imbalance decaying active regions can also give birth to lower latitude coronal holes. The accumulation of magnetic flux at coronal hole boundaries also creates conditions for filament formation: polar crown filaments are permanently present at the boundaries of the polar coronal holes. Mid-latitude and equatorial coronal holes - the result of active region evolution - can create pseudostreamers if other coronal holes of the same polarity are present. While helmet streamers form between open fields of opposite polarities, the pseudostreamer, characterized by a smaller coronal imprint, typically shows a more prominent straight ray or stalk extending from the corona. The pseudostreamer base at photospheric heights is multipolar; often one observes tripolar magnetic configurations with two neutral lines - where filaments can form - separating the coronal holes. Here we discuss the specific role of filament channels on pseudostreamer topology and on solar wind properties. 1D numerical analysis of pseudostreamers shows that the properties of the solar wind from around PSs depend on the presence/absence of filament channels, number of channels and chirality at thepseudostreamer base low in the corona. We review and model possible coronal magnetic configurations and solar wind plasma properties at different distances from the solar surface that may be observed by Parker Solar Probe and Solar Orbiter.

Coronal imbalance in Lenke 5C adolescent idiopathic scoliosis regarding selecting the lowest instrumented vertebra: Lower-end vertebra versus lower-end vertebra +1 in posterior fusion.

PubMed

Hu, Bowen; Yang, Xi; Yang, Huiliang; Liu, Limin; Chen, Peiran; Wang, Linnan; Zhu, Ce; Zhou, Chunguang; Song, Yueming

2018-06-18

Choosing the fusion level for posterior fusion in Lenke 5C adolescent idiopathic scoliosis patients is highly associated with coronal balance. Previous studies indicated that in patients with lowest end vertebra tilt > 25°, surgeons could extend distal fusion to avoid coronal imbalance. This study aimed to assess the risk factors for coronal imbalance in Lenke 5C scoliosis, and to discuss how to select fusion level. We reviewed 59 Lenke 5C AIS patients in one institution with at least 2-years' follow-up from 2010 through 2015. Preoperative, and 3-month and 2-year postoperative follow-up radiographs were measured using a number of specific measurements related to coronal balance. Patients were categorized into an LEV group and an LEV+1 group. Coronal imbalance was found in 6/31 patients in the LEV+1 group at final follow-up , and not in the LEV-group at the first or final follow-up. The C7 plumb line shifted to the convex side of the central sacral vertical line in 47/59 patients, including all of the 19 CIB patients after surgery. Patients who underwent fusion at LEV+1 with > 25° LEV tilt also showed poor results regarding coronal imbalance. Statistically, coronal balance at the final follow-up was correlated with preoperative bending lumbosacral hemi-curve (p=0.002) and all of the 6 patients with CIB had bending lumbosacral hemi-curve exceeds 15°. No significant difference were found in SRS-22 scores between the two groups at 2-year-follow-up. Distal fusion extension at LEV+1 is more likely to result in coronal imbalance at the first and final follow-up, especially when bending lumbosacral hemi-curve exceeds 15°. Fusion at LEV+1 should not be chosen when LEV is at L4. Copyright © 2018. Published by Elsevier Inc.

Evolution and Activity in the Solar Corona: A Comparison of Coronal and Chromospheric Structures Seen in Soft X-Rays, White Light and H-Alpha Emission

NASA Technical Reports Server (NTRS)

Bagenal, Fran

2001-01-01

The work completed under this project, 'Evolution and Activity in the Solar Corona: A Comparison of Coronal and Chromospheric Structures Seen in Soft X-Rays, White Light and H-Alpha Emission', includes the following presentations: (1) Analysis of H-alpha Observations of High-altitude Coronal Condensations; (2) Multi-spectral Imaging of Coronal Activity; (3) Measurement and Modeling of Soft X-ray Loop Arcades; (4) A Study of the Origin and Dynamics of CMEs; and various poster presentations and thesis dissertations.

Coronal partings

NASA Astrophysics Data System (ADS)

Nikulin, Igor F.; Dumin, Yurii V.

2016-02-01

The basic observational properties of "coronal partings"-the special type of quasi-one-dimensional magnetic structures, identified by a comparison of the coronal X-ray and EUV images with solar magnetograms-are investigated. They represent the channels of opposite polarity inside the unipolar large-scale magnetic fields, formed by the rows of magnetic arcs directed to the neighboring sources of the background polarity. The most important characteristics of the partings are discussed. It can be naturally assumed that-from the evolutionary and spatial points of view-the partings can transform into the coronal holes and visa versa. The classes of global, intersecting, and complex partings are identified.

40 CFR 81.307 - Connecticut.

Code of Federal Regulations, 2010 CFR

2010-07-01

... Attainment Plymouth Town Middlesex County (part) 1/2/96 Attainment Cromwell Town, Durham Town, E. Hampton.../Attainment Middlesex County (part) All portions except cities and towns in Hartford Area New London County... Middlesex County Nonattainment Serious. New Haven County Nonattainment Serious. New London County...

Study on the natural and humanistic environment of runcheng town

NASA Astrophysics Data System (ADS)

Huijun, Nie; Jinping, Wang

2018-03-01

Runcheng town is one of the first Chinese characteristic towns to be selected in Shanxi province. It is 38 kilometers from the Jin city and 7 kilometers from Yangcheng County. It’s also an important undertaking place for the project “Industrial Westward Move of Jincheng City” and an important tourist town of Qin Castle Valley. The Runcheng town has a history of thousands of years, with a deep cultural background and unique natural landscape. This paper studies the history and cultural resources and makes a preliminary study on the natural and humanistic environment of the Runcheng town.

The First Ionization Potential Effect from the Ponderomotive Force: On the Polarization and Coronal Origin of Alfvén Waves

NASA Astrophysics Data System (ADS)

Laming, J. Martin

2017-08-01

We investigate in more detail the origin of chromospheric Alfvén waves that give rise to the separation of ions and neutrals—the first ionization potential (FIP) effect—through the action of the ponderomotive force. In open field regions, we model the dependence of fractionation on the plasma upflow velocity through the chromosphere for both shear (or planar) and torsional Alfvén waves of photospheric origin. These differ mainly in their parametric coupling to slow mode waves. Shear Alfvén waves appear to reproduce observed fractionations for a wider range of model parameters and present less of a “fine-tuning” problem than do torsional waves. In closed field regions, we study the fractionations produced by Alfvén waves with photospheric and coronal origins. Waves with a coronal origin, at or close to resonance with the coronal loop, offer a significantly better match to observed abundances than do photospheric waves, with shear and torsional waves in such a case giving essentially indistinguishable fractionations. Such coronal waves are likely the result of a nanoflare coronal heating mechanism that, as well as heating coronal plasmas, releases Alfvén waves that can travel down to loop footpoints and cause FIP fractionation through the ponderomotive force as they reflect from the chromosphere back into the corona.

The First Ionization Potential Effect from the Ponderomotive Force: On the Polarization and Coronal Origin of Alfvén Waves

DOE Office of Scientific and Technical Information (OSTI.GOV)

Laming, J. Martin, E-mail: laming@nrl.navy.mil

We investigate in more detail the origin of chromospheric Alfvén waves that give rise to the separation of ions and neutrals—the first ionization potential (FIP) effect—through the action of the ponderomotive force. In open field regions, we model the dependence of fractionation on the plasma upflow velocity through the chromosphere for both shear (or planar) and torsional Alfvén waves of photospheric origin. These differ mainly in their parametric coupling to slow mode waves. Shear Alfvén waves appear to reproduce observed fractionations for a wider range of model parameters and present less of a “fine-tuning” problem than do torsional waves. Inmore » closed field regions, we study the fractionations produced by Alfvén waves with photospheric and coronal origins. Waves with a coronal origin, at or close to resonance with the coronal loop, offer a significantly better match to observed abundances than do photospheric waves, with shear and torsional waves in such a case giving essentially indistinguishable fractionations. Such coronal waves are likely the result of a nanoflare coronal heating mechanism that, as well as heating coronal plasmas, releases Alfvén waves that can travel down to loop footpoints and cause FIP fractionation through the ponderomotive force as they reflect from the chromosphere back into the corona.« less

A universal model for solar eruptions.

PubMed

Wyper, Peter F; Antiochos, Spiro K; DeVore, C Richard

2017-04-26

Magnetically driven eruptions on the Sun, from stellar-scale coronal mass ejections to small-scale coronal X-ray and extreme-ultraviolet jets, have frequently been observed to involve the ejection of the highly stressed magnetic flux of a filament. Theoretically, these two phenomena have been thought to arise through very different mechanisms: coronal mass ejections from an ideal (non-dissipative) process, whereby the energy release does not require a change in the magnetic topology, as in the kink or torus instability; and coronal jets from a resistive process involving magnetic reconnection. However, it was recently concluded from new observations that all coronal jets are driven by filament ejection, just like large mass ejections. This suggests that the two phenomena have physically identical origin and hence that a single mechanism may be responsible, that is, either mass ejections arise from reconnection, or jets arise from an ideal instability. Here we report simulations of a coronal jet driven by filament ejection, whereby a region of highly sheared magnetic field near the solar surface becomes unstable and erupts. The results show that magnetic reconnection causes the energy release via 'magnetic breakout'-a positive-feedback mechanism between filament ejection and reconnection. We conclude that if coronal mass ejections and jets are indeed of physically identical origin (although on different spatial scales) then magnetic reconnection (rather than an ideal process) must also underlie mass ejections, and that magnetic breakout is a universal model for solar eruptions.

Critical Magnetic Field Strengths for Unipolar Solar Coronal Plumes In Quiet Regions and Coronal Holes?

NASA Technical Reports Server (NTRS)

Avallone, Ellis; Tiwari, Sanjiv K.; Panesar, Navdeep K.; Moore, Ronald L.; Winebarger, Amy

2017-01-01

Coronal plumes are bright magnetic funnels that are found in quiet regions and coronal holes that extend high into the solar corona whose lifetimes can last from hours to days. The heating processes that make plumes bright involve the magnetic field at the base of the plume, but their intricacies remain mysterious. Raouafi et al. (2014) infer from observation that plume heating is a consequence of magnetic reconnection at the base, whereas Wang et al. (2016) infer that plume heating is a result of convergence of the magnetic flux at the plume's base, or base flux. Both papers suggest that the base flux in their plumes is of mixed polarity, but do not quantitatively measure the base flux or consider whether a critical magnetic field strength is required for plume production. To investigate the magnetic origins of plume heating, we track plume luminosity in the 171 Å wavelength as well as the abundance and strength of the base flux over the lifetimes of six unipolar coronal plumes. Of these, three are in coronal holes and three are in quiet regions. For this sample, we find that plume heating is triggered when convergence of the base flux surpasses a field strength of approximately 300 - 500 Gauss, and that the luminosity of both quiet region and coronal hole plumes respond similarly to the strength of the magnetic field in the base.

Added Value of Coronal Reformations for Duty Radiologists and for Referring Physicians or Surgeons in the CT Diagnosis of Acute Appendicitis

PubMed Central

Lee, Kyoung Ho; Hahn, Seokyung; Lee, Kyung Won; Lee, Hak Jong; Kim, Tae Jung; Kang, Sung-Bum; Shin, Joong Ho; Park, Byung Joo

2006-01-01

Objective To assess the added value of coronal reformation for radiologists and for referring physicians or surgeons in the CT diagnosis of acute appendicitis. Materials and Methods Contrast-enhanced CT was performed using 16-detector-row scanners in 110 patients, 46 of whom had appendicitis. Transverse (5-mm thickness, 4-mm increment), coronal (5-mm thickness, 4-mm increment), and combined transverse and coronal sections were interpreted by four radiologists, two surgeons and two emergency physicians. The area under the receiver operating characteristic curve (Az value), sensitivity, specificity (McNemar test), diagnostic confidence and appendiceal visualization (Wilcoxon signed rank test) were compared. Results For radiologists, the additional coronal sections tended to increase the Az value (0.972 vs. 0.986, p = 0.076) and pooled sensitivity (92% [95% CI: 88, 96] vs. 96% [93, 99]), and enhanced appendiceal visualization in true-positive cases (p = 0.031). For non-radiologists, no such enhancement was observed, and the confidence for excluding acute appendicitis declined (p = 0.013). Coronal sections alone were inferior to transverse sections for diagnostic confidence as well as appendiceal visualization for each reader group studied (p < 0.05). Conclusion The added value of coronal reformation is more apparent for radiologists compared to referring physicians or surgeons in the CT diagnosis of acute appendicitis. PMID:16799269

The psychological well-being of children orphaned by AIDS in Cape Town, South Africa

PubMed Central

Cluver, Lucie; Gardner, Frances

2006-01-01

Background An estimated 2 million children are parentally bereaved by AIDS in South Africa. Little is known about mental health outcomes for this group. Methods This study aimed to investigate mental health outcomes for urban children living in deprived settlements in Cape Town. 30 orphaned children and 30 matched controls were compared using standardised questionnaires (SDQ) on emotional and behavioural problems, peer and attention difficulties, and prosocial behaviour. The orphan group completed a modified version of a standardised questionnaire (IES-8), measuring Post-Traumatic Stress symptoms. Group differences were tested using t-tests and Pearson's chi-square. Results Both groups scored highly for peer problems, emotional problems and total scores. However, orphans were more likely to view themselves as having no good friends (p = .002), to have marked concentration difficulties (p = .03), and to report frequent somatic symptoms (p = .05), but were less likely to display anger through loss of temper (p = .03). Orphans were more likely to have constant nightmares (p = .01), and 73% scored above the cut-off for Post-Traumatic Stress Disorder. Conclusion Findings suggest important areas for larger-scale research for parentally-bereaved children. PMID:16848910

The Labial-Coronal Effect Revisited: Japanese Adults Say Pata, but Hear Tapa

ERIC Educational Resources Information Center

Tsuji, Sho; Gomez, Nayeli Gonzalez; Medina, Victoria; Nazzi, Thierry; Mazuka, Reiko

2012-01-01

The labial-coronal effect has originally been described as a bias to initiate a word with a labial consonant-vowel-coronal consonant (LC) sequence. This bias has been explained with constraints on the human speech production system, and its perceptual correlates have motivated the suggestion of a perception-production link. However, previous…

Solar and stellar coronal plasmas

NASA Technical Reports Server (NTRS)

Golub, L.

1985-01-01

Progress made in describing and interpreting coronal plasma processes and the relationship between the solar corona and its stellar counterparts is reported. Topics covered include: stellar X-ray emission, HEAO 2 X-ray survey of the Pleiades, closed coronal structures, X-ray survey of main-sequence stars with shallow convection zones, implications of the 1400 MHz flare emission, and magnetic field stochasticity.

View of coronal hole processed from television transmission of ATM

NASA Image and Video Library

1973-08-20

S73-32883 (20 Aug. 1973) --- This false color isophote, processed from an Aug. 20, 1973 television transmission of Apollo Telescope Mount (ATM) experiments from Skylab 3, dramatically reveals a significant change in the coronal hole as compared to the previous day. Solar rotation accounts for the new location of the coronal hole. Photo credit: NASA

Perceived descriptive safety-related driving norms within and outside Arab towns and villages in Israel.

PubMed

Baron-Epel, Orna; Obid, Samira; Fertig, Shahar; Gitelman, Victoria

2016-01-01

Involvement in car crashes is higher among Israeli Arabs compared to Jews. This study characterized perceived descriptive driving norms (PDDNs) within and outside Arab towns/villages and estimated their association with involvement in car crashes. Arab drivers (594) living in 19 towns and villages were interviewed in face-to-face interviews. The questionnaire included questions about involvement in car crashes, PDDNs within and outside the towns/villages, attitudes toward traffic safety laws, traffic law violations, and socioeconomic and demographic variables. PDDNs represent individuals' perceptions on how safe other people typically drive. The low scores indicate a low percentage of drivers performing unsafe behaviors (safer driving-related norms). A structural equation modeling analysis was applied to identify factors associated with PDDNs and involvement in car crashes. A large difference was found in PDDNs within and outside the towns/villages. Mostly, the respondents reported higher rates of unsafe PDDNs within the towns/villages (mean = 3.76, SD = 0.63) and lower rates of PDDNs outside the towns/villages (mean = 2.12, SD = 0.60). PDDNs outside the towns/villages were associated with involvement in a car crash (r = -0.12, P <.01), but those within the towns/villages were not. Within the towns/villages, attitudes toward traffic laws and PDDNs were positively associated with traffic law violations (r = 0.56, P <.001; r = 0.11, P <.001 respectively), where traffic law violations were directly associated with involvement in a car crash (r = -0.14, P <.001). Unsafe PDDNs may add directly and indirectly to unsafe driving and involvement in car crashes in Arab Israelis. Because PDDNs outside towns/villages were better, increased law enforcement within towns/villages may improve these norms and decrease involvement in car crashes.

Coronal Seismology -- Achievements and Perspectives

NASA Astrophysics Data System (ADS)

Ruderman, Michael

Coronal seismology is a new and fast developing branch of the solar physics. The main idea of coronal seismology is the same as of any branches of seismology: to determine basic properties of a medium using properties of waves propagating in this medium. The waves and oscillations in the solar corona are routinely observed in the late space missions. In our brief review we concentrate only on one of the most spectacular type of oscillations observed in the solar corona - the transverse oscillations of coronal magnetic loops. These oscillations were first observed by TRACE on 14 July 1998. At present there are a few dozens of similar observations. Shortly after the first observation of the coronal loop transverse oscillations they were interpreted as kink oscillations of magnetic tubes with the ends frozen in the dense photospheric plasma. The frequency of the kink oscillation is proportional to the magnetic field magnitude and inversely proportional to the tube length times the square root of the plasma density. This fact was used to estimate the magnetic field magnitude in the coronal loops. In 2004 the first simultaneous observation of the fundamental mode and first overtone of the coronal loop transverse oscillation was reported. If we model a coronal loop as a homogeneous magnetic tube, then the ratio of the frequencies of the first overtone and the fundamental mode should be equal to 2. However, the ratio of the observed frequencies was smaller than 2. This is related to the density variation along the loop. If we assume that the corona is isothermal and prescribe the loop shape (usually it is assumed that it has the shape of half-circle), then, using the ratio of the two frequencies, we can determine the temperature of the coronal plasma. The first observation of transverse oscillations of the coronal loops showed that they were strongly damped. This phenomenon was confirmed by the subsequent observations. At present, the most reliable candidate for the explanation of the oscillation damping is resonant absorption. The damping due to resonant absorption is, broadly speaking, proportional to the inhomogeneity scale of the density in the loop in the transverse direction. This fact was used to estimate the density inhomogeneity scale from the observations. The first observation of the coronal loop transverse oscillations gave a strong boost to the theoretical study of this phenomenon. In the last ten years theorists sufficiently refined their models taking into account such loop properties as the density variation in the longitudinal and transverse directions, the twist of the magnetic field, the non-circular loop cross-section, the variation of the cross-section along the loop, and the loop curvature. Now, to obtain more accurate estimates of the coronal plasma parameters, we need the following from the observations: (i) Since the frequency of the loop oscillation depends on the plasma density, more accurate data on this quantity is required. (ii) Since the estimate of the coronal temperature strongly depends of the loop shape, an accurate three-dimensional picture of the loop is desirable. (iii) The fundamental frequency and first overtone of the loop oscillation are sufficiently affected by the variation of the loop cross-section. The observational data on this quantity is important for further progress of the coronal seismology.

[Cardiovascular diseases risk factors knowledge among soldiers of the Polish army].

PubMed

Olszewski, Robert; Grabysa, Radosław; Kwasiborski, Przemysław J; Makowski, Tomasz; Warmiński, Janusz; Szczechowicz, Robert; Kubik, Leszek

2009-10-01

Cardiovascular diseases (CVDs) are the main cause of death and disability in Poland. There are many risk factors of CVD which are modifiable due to preventive strategies. Knowledge about these factors among population at risk of CVD is the most important condition for success of them. To evaluate the knowledge of CVD risk factors among soldiers of the Polish Army and try to identify a demographic factors influenced on them. Authors investigated the level of knowledge about CVD risk factors among 644 soldiers (aged between 18 to 62 years) using the special questionnaire. Whole group was analyzed according to a place of origin: city, town and village and according to a function: professionals and conscripts. Soldiers achieved a total score of 58.4% correct answers. Commonly known risk factors of CVD (average 82% of correct answers) in studied group were: obesity, tobacco smoking, high level of cholesterol and hypertension. Knowledge about above risk factors was significantly higher (p < 0.01) than about other. Lesser known risk factors (average 54% of correct answers) were: male gender, abnormal diet, sedentary lifestyle, family history of CVDs, diabetes, family history of heart infarction below 55 yrs and peripheral atherosclerosis. residents achieved 64.5% correct answers, town--61.5%, and village--58%. Professionals achieved 65.1% vs. 58.8% for conscripts. The level of knowledge about CVD risk factors are significantly higher among professionals than in urban population. Our data confirm the need of continuation and developing new CVDs preventive strategies in Poland, especially among poor educated and village populations. There is a need to emphasize the role of lesser known, modifiable CVD risk factors (e.g., obesity, sedentary lifestyle) in existing and future health programs.

Contagious Coronal Heating from Recurring Emergence of Magnetic Flux

NASA Astrophysics Data System (ADS)

Moore, R. L.; Falconer, D. A.; Sterling, A. C.

2002-01-01

For each of six old bipolar active regions, we present and interpret Yohkoh/SXT and SOHO/MDI observations of the development, over several days, of enhanced coronal heating in and around the old bipole in response to new magnetic flux emergence within the old bipole. The observations show: 1. In each active region, new flux emerges in the equatorward side of the old bipole, around a lone remaining leading sunspot and/or on the equatorward end of the neutral line of the old bipole. 2. The emerging field is marked by intense internal coronal heating, and enhanced coronal heating occurs in extended loops stemming from the emergence site. 3. In five of the six cases, a "rooster tail" of coronal loops in the poleward extent of the old bipole also brightens in response to the flux emergence. 4. There are episodes of enhanced coronal heating in surrounding magnetic fields that are contiguous with the old bipole but are not directly connected to the emerging field. From these observations, we suggest that the accommodation of localized newly emerged flux within an old active region entails far reaching adjustments in the 3D magnetic field throughout the active region and in surrounding fields in which the active region is embedded, and that these adjustments produce the extensive enhanced coronal heating. We Also Note That The Reason For The recurrence of flux emergence in old active regions may be that active-region flux tends to emerge in giant-cell convection downflows. If so, the poleward "rooster tail" is a coronal flag of a long-lasting downflow in the convection zone. This work was funded by NASA's Office of Space Science through the Solar Physics Supporting Research and Technology Program and the Sun-Earth Connection Guest Investigator Program.

Classification and Physical parameters EUV coronal jets with STEREO/SECCHI.

NASA Astrophysics Data System (ADS)

Nistico, Giuseppe; Bothmer, Volker; Patsourakos, Spiro; Zimbardo, Gaetano

In this work we present observations of EUV coronal jets, detected with the SECCHI (Sun Earth Connection Coronal and Heliospheric Investigation) imaging suites of the two STEREO spacecraft. Starting from catalogues of polar and equatorial coronal hole jets (Nistico' et al., Solar Phys., 259, 87, 2009; Ann. Geophys. in press), identified from simultaneous EUV and white-light coronagraph observations, taken during the time period March 2007 to April 2008 when solar activity was at minimum, we perfom a detailed study of some events. A basic char-acterisation of the magnetic morphology and identification of the presence of helical structure were established with respect to recently proposed models for their origin and temporal evo-lution. A classification of the events with respect to previous jet studies shows that amongst the 79 events, identified into polar coronal holes, there were 37 Eiffel tower -type jet events commonly interpreted as a small-scale ( 35 arcsec) magnetic bipole reconnecting with the ambi-ent unipolar open coronal magnetic fields at its looptops, 12 lambda-type jet events commonly interpreted as reconnection with the ambient field happening at the bipoles footpoints. Five events were termed micro-CME type jet events because they resembled classical three-part structured coronal mass ejections (CMEs) but on much smaller scales. The remainig 25 cases could not be uniquely classified. Thirty-one of the total number of events exhibited a helical magnetic field structure, indicative for a torsional motion of the jet around its axis of propaga-tion. The jet events are found to be also present in equatorial coronal holes. We also present the 3-D reconstruction, temperature, velocity, and density measurements of a number of jets during their evolution.

DERIVING THE PROPERTIES OF CORONAL PRESSURE FRONTS IN 3D: APPLICATION TO THE 2012 MAY 17 GROUND LEVEL ENHANCEMENT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rouillard, A. P.; Plotnikov, I.; Pinto, R. F.

2016-12-10

We study the link between an expanding coronal shock and the energetic particles measured near Earth during the ground level enhancement of 2012 May 17. We developed a new technique based on multipoint imaging to triangulate the three-dimensional (3D) expansion of the shock forming in the corona. It uses images from three vantage points by mapping the outermost extent of the coronal region perturbed by the pressure front. We derive for the first time the 3D velocity vector and the distribution of Mach numbers, M {sub FM}, of the entire front as a function of time. Our approach uses magneticmore » field reconstructions of the coronal field, full magnetohydrodynamic simulations and imaging inversion techniques. We find that the highest M {sub FM} values appear near the coronal neutral line within a few minutes of the coronal mass ejection onset; this neutral line is usually associated with the source of the heliospheric current and plasma sheet. We illustrate the variability of the shock speed, shock geometry, and Mach number along different modeled magnetic field lines. Despite the level of uncertainty in deriving the shock Mach numbers, all employed reconstruction techniques show that the release time of GeV particles occurs when the coronal shock becomes super-critical ( M {sub FM} > 3). Combining in situ measurements with heliospheric imagery, we also demonstrate that magnetic connectivity between the accelerator (the coronal shock of 2012 May 17) and the near-Earth environment is established via a magnetic cloud that erupted from the same active region roughly five days earlier.« less

Morphology of Pseudostreamers and Solar Wind Properties

NASA Astrophysics Data System (ADS)

Panasenco, Olga; Velli, Marco

2016-05-01

The solar dynamo and photospheric convection lead to three main types of structures extending from the solar surface into the corona - active regions, solar filaments (prominences when observed at the limb) and coronal holes. These structures exist over a wide range of scales, and are interlinked with each other in evolution and dynamics. Active regions can form clusters of magnetic activity and the strongest overlie sunspots. In the decay of active regions, the boundaries separating opposite magnetic polarities (neutral lines) develop the specific structures called filament channels above which filaments form. In the presence of flux imbalance decaying active regions can also give birth to lower latitude coronal holes. The accumulation of magnetic flux at coronal hole boundaries also creates the conditions for filament formation: polar crown filaments are permanently present at the boundaries of the polar coronal holes. Middle-latitude and equatorial coronal holes - the result of active region evolution - can create pseudostreamers (PSs) if other coronal holes of the same polarity are present. While helmet streamers form between open fields of opposite polarities, the pseudostreamer, characterized by a smaller coronal imprint, typically shows a more prominent straight ray or stalk extending from the corona. The pseudostreamer base at photospheric heights is multipolar; often one observes tripolar magnetic configurations with two neutral lines - where filaments can form - separating the coronal holes. Here we discuss the specific role of filament channels on pseudostreamer topology and on solar wind properties. 1D numerical analysis of PSs shows that the properties of the solar wind from around PSs depend on the presence/absence of filament channels, number of channels and chirality at the PS base low in the corona.

Coronal "wave": Magnetic Footprint Of A Cme?

NASA Astrophysics Data System (ADS)

Attrill, Gemma; Harra, L. K.; van Driel-Gesztelyi, L.; Demoulin, P.; Wuelser, J.

2007-05-01

We propose a new mechanism for the generation of "EUV coronal waves". This work is based on new analysis of data from SOHO/EIT, SOHO/MDI & STEREO/EUVI. Although first observed in 1997, the interpretation of coronal waves as flare-induced or CME-driven remains a debated topic. We investigate the properties of two "classical" SOHO/EIT coronal waves in detail. The source regions of the associated CMEs possess opposite helicities & the coronal waves display rotations in opposite senses. We observe deep dimmings near the flare site & also widespread diffuse dimming, accompanying the expansion of the EIT wave. We report a new property of these EIT waves, namely, that they display dual brightenings: persistent ones at the outermost edge of the core dimming regions & simultaneously diffuse brightenings constituting the leading edge of the coronal wave, surrounding the expanding diffuse dimmings. We show that such behaviour is consistent with a diffuse EIT wave being the magnetic footprint of a CME. We propose a new mechanism where driven magnetic reconnections between the skirt of the expanding CME & quiet-Sun magnetic loops generate the observed bright diffuse front. The dual brightenings & widespread diffuse dimming are identified as innate characteristics of this process. In addition we present some of the first analysis of a STEREO/EUVI limb coronal wave. We show how the evolution of the diffuse bright front & dimmings can be understood in terms of the model described above. We show that an apparently stationary part of the bright front can be understood in terms of magnetic interchange reconnections between the expanding CME & the "open" magnetic field of a low-latitude coronal hole. We use both the SOHO/EIT & STEREO/EUVI events to demonstrate that through successive reconnections, this new model provides a natural mechanism via which CMEs can become large-scale in the lower corona.

Contagious Coronal Heating from Recurring Emergence of Magnetic Flux

NASA Technical Reports Server (NTRS)

Moore, Ronald L.; Falconer, David; Sterling, Alphonse; Whitaker, Ann F. (Technical Monitor)

2001-01-01

For each of six old bipolar active regions, we present and interpret Yohkoh/SXT and SOHO/MDI observations of the development, over several days, of enhanced coronal heating in and around the old bipole in response to new magnetic flux emerge= within the old bipole. The observations show: 1. In each active region, new flux emerges in the equatorward side of the old bipole, around a lone remaining leading sunspot and/or on the equatorward end of the neutral line of the old bipole. 2. The emerging field is marked by intense internal coronal heating, and enhanced coronal heating occurs in extended loops stemming from the emergence site. 3. In five of the six cases, a "rooster tail" of coronal loops in the poleward extent of the old bipole also brightens in response to the flux emergence. 4. There are episodes of enhanced coronal heating in surrounding magnetic fields that are contiguous with the old bipole but are not directly connected to the emerging field. From these observations, we suggest that the accommodation of localized newly emerged flux within an old active region entails far reaching adjustments in the 3D magnetic field throughout the active region and in surrounding fields in which the active region is embedded, and that these adjustments produce the extensive enhanced coronal heating. We also note that the reason for the recurrence of flux emergence in old active regions may be that active region flux tends to emerge in giant-cell convection downflows. If so, the poleward "rooster tail" is a coronal flag of a long-lasting downflow in the convection zone. This work was funded by NASA's Office of Space Science through the Solar Physics Supporting Research and Technology Program and the Sun-Earth Connection Guest Investigator Program.

CME Interaction with Coronal Holes and Their Interplanetary Consequences

NASA Technical Reports Server (NTRS)

Gopalswamy, N.; Makela, P.; Xie, H.; Akiyama, S.; Yashiro, S.

2008-01-01

A significant number of interplanetary (IP) shocks (-17%) during cycle 23 were not followed by drivers. The number of such "driverless" shocks steadily increased with the solar cycle with 15%, 33%, and 52% occurring in the rise, maximum, and declining phase of the solar cycle. The solar sources of 15% of the driverless shocks were very close the central meridian of the Sun (within approx.15deg), which is quite unexpected. More interestingly, all the driverless shocks with their solar sources near the solar disk center occurred during the declining phase of solar cycle 23. When we investigated the coronal environment of the source regions of driverless shocks, we found that in each case there was at least one coronal hole nearby suggesting that the coronal holes might have deflected the associated coronal mass ejections (CMEs) away from the Sun-Earth line. The presence of abundant low-latitude coronal holes during the declining phase further explains why CMEs originating close to the disk center mimic the limb CMEs, which normally lead to driverless shocks due to purely geometrical reasons. We also examined the solar source regions of shocks with drivers. For these, the coronal holes were located such that they either had no influence on the CME trajectories. or they deflected the CMEs towards the Sun-Earth line. We also obtained the open magnetic field distribution on the Sun by performing a potential field source surface extrapolation to the corona. It was found that the CMEs generally move away from the open magnetic field regions. The CME-coronal hole interaction must be widespread in the declining phase, and may have a significant impact on the geoeffectiveness of CMEs.

Comparison of Two Coronal Magnetic Field Models to Reconstruct a Sigmoidal Solar Active Region with Coronal Loops

NASA Astrophysics Data System (ADS)

Duan, Aiying; Jiang, Chaowei; Hu, Qiang; Zhang, Huai; Gary, G. Allen; Wu, S. T.; Cao, Jinbin

2017-06-01

Magnetic field extrapolation is an important tool to study the three-dimensional (3D) solar coronal magnetic field, which is difficult to directly measure. Various analytic models and numerical codes exist, but their results often drastically differ. Thus, a critical comparison of the modeled magnetic field lines with the observed coronal loops is strongly required to establish the credibility of the model. Here we compare two different non-potential extrapolation codes, a nonlinear force-free field code (CESE-MHD-NLFFF) and a non-force-free field (NFFF) code, in modeling a solar active region (AR) that has a sigmoidal configuration just before a major flare erupted from the region. A 2D coronal-loop tracing and fitting method is employed to study the 3D misalignment angles between the extrapolated magnetic field lines and the EUV loops as imaged by SDO/AIA. It is found that the CESE-MHD-NLFFF code with preprocessed magnetogram performs the best, outputting a field that matches the coronal loops in the AR core imaged in AIA 94 Å with a misalignment angle of ˜10°. This suggests that the CESE-MHD-NLFFF code, even without using the information of the coronal loops in constraining the magnetic field, performs as good as some coronal-loop forward-fitting models. For the loops as imaged by AIA 171 Å in the outskirts of the AR, all the codes including the potential field give comparable results of the mean misalignment angle (˜30°). Thus, further improvement of the codes is needed for a better reconstruction of the long loops enveloping the core region.

Joint SDO and IRIS Observations of a Novel, Hybrid Prominence-Coronal Rain Complex

NASA Astrophysics Data System (ADS)

Liu, Wei; Antolin, Patrick; Sun, Xudong; Gao, Lijia; Vial, Jean-Claude; Gibson, Sarah; Okamoto, Takenori; Berger, Thomas; Uitenbroek, Han; De Pontieu, Bart

2016-10-01

Solar prominences and coronal rain are intimately related phenomena, both involving cool material at chromospheric temperatures within the hot corona and both playing important roles as part of the return flow of the chromosphere-corona mass cycle. At the same time, they exhibit distinct morphologies and dynamics not yet well understood. Quiescent prominences consist of numerous long-lasting, filamentary downflow threads, while coronal rain is more transient and falls comparably faster along well-defined curved paths. We report here a novel, hybrid prominence-coronal rain complex in an arcade-fan geometry observed by SDO/AIA and IRIS, which provides new insights to the underlying physics of such contrasting behaviors. We found that the supra-arcade fan region hosts a prominence sheet consisting of meandering threads with broad line widths. As the prominence material descends to the arcade, it turns into coronal rain sliding down coronal loops with line widths 2-3 times narrower. This contrast suggests that distinct local plasma and magnetic conditions determine the fate of the cool material, a scenario supported by our magnetic field extrapolations from SDO/HMI. Specifically, the supra-arcade fan (similar to those in solar flares; e.g., McKenzie 2013) is likely situated in a current sheet, where the magnetic field is weak and the plasma-beta could be close to unity, thus favoring turbulent flows like those prominence threads. In contrast, the underlying arcade has a stronger magnetic field and most likely a low-beta environment, such that the material is guided along magnetic field lines to appear as coronal rain. We will discuss the physical implications of these observations beyond prominence and coronal rain.

Magnetic Flux Cancellation as the Trigger of Solar Coronal Jets

NASA Astrophysics Data System (ADS)

McGlasson, R.; Panesar, N. K.; Sterling, A. C.; Moore, R. L.

2017-12-01

Coronal jets are narrow eruptions in the solar corona, and are often observed in extreme ultraviolet (EUV) and X-ray images. They occur everywhere on the solar disk: in active regions, quiet regions, and coronal holes (Raouafi et al. 2016). Recent studies indicate that most coronal jets in quiet regions and coronal holes are driven by the eruption of a minifilament (Sterling et al. 2015), and that this eruption follows flux cancellation at the magnetic neutral line under the pre-eruption minifilament (Panesar et al. 2016). We confirm this picture for a large sample of jets in quiet regions and coronal holes using multithermal (304 Å 171 Å, 193 Å, and 211 Å) extreme ultraviolet (EUV) images from the Solar Dynamics Observatory (SDO) /Atmospheric Imaging Assembly (AIA) and line-of-sight magnetograms from the SDO /Helioseismic and Magnetic Imager (HMI). We report observations of 60 randomly selected jet eruptions. We have analyzed the magnetic cause of these eruptions and measured the base size and the duration of each jet using routines in SolarSoft IDL. By examining the evolutionary changes in the magnetic field before, during, and after jet eruption, we found that each of these jets resulted from minifilament eruption triggered by flux cancellation at the neutral line. In agreement with the above studies, we found our jets to have an average base diameter of 7600 ± 2700 km and an average duration of 9.0 ± 3.6 minutes. These observations confirm that minifilament eruption is the driver and magnetic flux cancellation is the primary trigger mechanism for nearly all coronal hole and quiet region coronal jet eruptions.

Impact of the quality of coronal restoration and root canal filling on the periapical health in adult syrian subpopulation

PubMed Central

Alafif, Hisham

2014-01-01

Background: The purpose of this study was to determine the status of periapical tissues of endodontically treated teeth according to coronal restorations and root canal fillings separately and in concomitant in adult Syrian subpopulation. Methods: 784 endodontically treated teeth from two hundred randomly selected Syrian adult patients were radiographically evaluated. According to predetermined criteria, the quality of coronal restorations and root canal filling of each tooth was scored as adequate or inadequate. The status of periapical tissues was also classified as healthy or diseased. Results were analyzed using Chi-squared test. Results: Adequate coronal restorations were determined in 58.54% of cases which was accompanied with less periapical pathosis than that in teeth with inadequate restorations (P < 0.01). 14% of teeth were restored by posts which showed no significant impact on the periapical tissues health. 18.5% of endodontic treatments were evaluated as adequate with less number of periapical radiolucencies than that of inadequate root canal fillings (P < 0.01). Absence of periapical pathosis was 96.6% in cases with both adequate coronal restorations and root canals fillings. The rate was 88.5% in cases with only adequate root canals fillings, and about 70% in cases with only adequate coronal restorations. When the treatment was inadequate in both coronal and root canals fillings, success rate was only observed in 48.8%. Conclusion: The most important factor with regard to the periradicular tissue health is the quality of root canal filling without neglecting the influence of coronal restoration (regardless of its type). There is a high prevalence rate of periapical pathosis in Syrian subpopulation due to poor dental practice. PMID:25565729

Comparison of Two Coronal Magnetic Field Models to Reconstruct a Sigmoidal Solar Active Region with Coronal Loops

DOE Office of Scientific and Technical Information (OSTI.GOV)

Duan, Aiying; Zhang, Huai; Jiang, Chaowei

Magnetic field extrapolation is an important tool to study the three-dimensional (3D) solar coronal magnetic field, which is difficult to directly measure. Various analytic models and numerical codes exist, but their results often drastically differ. Thus, a critical comparison of the modeled magnetic field lines with the observed coronal loops is strongly required to establish the credibility of the model. Here we compare two different non-potential extrapolation codes, a nonlinear force-free field code (CESE–MHD–NLFFF) and a non-force-free field (NFFF) code, in modeling a solar active region (AR) that has a sigmoidal configuration just before a major flare erupted from themore » region. A 2D coronal-loop tracing and fitting method is employed to study the 3D misalignment angles between the extrapolated magnetic field lines and the EUV loops as imaged by SDO /AIA. It is found that the CESE–MHD–NLFFF code with preprocessed magnetogram performs the best, outputting a field that matches the coronal loops in the AR core imaged in AIA 94 Å with a misalignment angle of ∼10°. This suggests that the CESE–MHD–NLFFF code, even without using the information of the coronal loops in constraining the magnetic field, performs as good as some coronal-loop forward-fitting models. For the loops as imaged by AIA 171 Å in the outskirts of the AR, all the codes including the potential field give comparable results of the mean misalignment angle (∼30°). Thus, further improvement of the codes is needed for a better reconstruction of the long loops enveloping the core region.« less

Two-Component Fitting of Coronal-Hole and Quiet-Sun He I 1083 Spectra

NASA Technical Reports Server (NTRS)

Jones, Harrison P.; Malanushenko, Elena V.; Fisher, Richard R. (Technical Monitor)

2001-01-01

We present reduction techniques and first results for detailed fitting of solar spectra obtained with the NASA/National Solar Observatory Spectromagnetograph (NASA/NSO SPM over a 2 nm bandpass centered on the He 1 1083 nm line. The observation for this analysis was a spectra-spectroheliogram obtained at the NSO/Kitt Peak Vacuum Telescope (KPVT) on 00 Apr 17 at 21:46 UT spanning an area of 512 x 900 arc-seconds; the field of view included a coronal hole near disk center as well as surrounding quiet sun. Since the He I line is very weak and blended with nearby solar and telluric lines, accurate determination of the continuum intensity as a function of wavelength is crucial. We have modified the technique of Malanushenko {\\it et al.) (1992; {\\it AA) (\\bf 259), 567) to tie regions of continuua and the wings of spectral lines which show little variation over the image to standard reference spectra such as the NSO Fourier Transform Spectrometer atlas (Wallace {\\it et al). 1993; NSO Tech Report \\#93-001). We performed detailed least-squares fits of spectra from selected areas, accounting for all the known telluric and solar absorbers in the spectral bandpass. The best physically consistent fits to the Helium lines were obtained with Gaussian profiles from two components (one ''cool'', characteristic of the upper chromosphere; one ''hot'', representing the cool transition region at 2-3 x 10$^{4)$ K). In the coronal hole, the transition-region component, shifted by 6-7 km/s to the blue, is mildly dominant, consistent with mass outflow as suggested by Dupree {\\it et all. (1996; {\\it Ap. J.}-{\\bf 467), 121). In quiet-sun spectra there is less evidence of outward flow, and the chromospheric component is more important. All our fitted spectra show a very weak unidentified absorption feature at 1082.880 nm in the red wing of the nearby Si I line.

Particle/fluid simulations of an eruptive flare: Identifying the field-aligned currents responsible for the hard x-rays

NASA Astrophysics Data System (ADS)

Winglee, R. M.

1994-09-01

While magnetohydrodynamics (MHD) can provide a reasonable description of the overall magnetic reconnection that is believed to drive flares, additional, and often separate processes have to be envoked to in order to explain the electron acceleration that is responsible for many of the observed flare emissions. A new model that incorporates the dynamic coronal current sheets, the reconnection site, and possible electron acceleration processes is developed through the use of two-dimensional particle and modified two-fluid simulations. The specific example of an eruptive flare driven by the coalescence of flux tubes supported by prescribed photospheric current elements is evaluated. It is shown that the electrons and ions have differential trajectories through the coronal current sheet which leads to the development of additonal plasma currents that flow around the surface of the current sheet. These surface currents are explicitly neglected in MHD but they are vital to the flare dynamics because they divert current from the coronal current sheet into the chromosphere, producing an effective resistivity that aids the development of fast reconnection. Because the surface currents are in the plane of the magnetic field, electrons in them experience strong acceleration and can account for the observed hard X-ray emissions. Model predictions are compared with observed time profiles of hard X-ray emissions and Doppler shifts seen in soft X-ray line emissions and are able to account for such features as (1) the asymmetry in the rise and decay time of the hard X-rays, (2) the apparent delay between the largest Doppler shifts and the hard X-ray peak, and (3) the relatively low intensity of the blue-shifted component. The use of particle and fluid simulations is important because it provides different, but complementary treatments of the electron acceleration, the global magnetic morphology, and the flare current system.

Turbulent Heating and Wave Pressure in Solar Wind Acceleration Modeling: New Insights to Empirical Forecasting of the Solar Wind

NASA Astrophysics Data System (ADS)

Woolsey, L. N.; Cranmer, S. R.

2013-12-01

The study of solar wind acceleration has made several important advances recently due to improvements in modeling techniques. Existing code and simulations test the competing theories for coronal heating, which include reconnection/loop-opening (RLO) models and wave/turbulence-driven (WTD) models. In order to compare and contrast the validity of these theories, we need flexible tools that predict the emergent solar wind properties from a wide range of coronal magnetic field structures such as coronal holes, pseudostreamers, and helmet streamers. ZEPHYR (Cranmer et al. 2007) is a one-dimensional magnetohydrodynamics code that includes Alfven wave generation and reflection and the resulting turbulent heating to accelerate solar wind in open flux tubes. We present the ZEPHYR output for a wide range of magnetic field geometries to show the effect of the magnetic field profiles on wind properties. We also investigate the competing acceleration mechanisms found in ZEPHYR to determine the relative importance of increased gas pressure from turbulent heating and the separate pressure source from the Alfven waves. To do so, we developed a code that will become publicly available for solar wind prediction. This code, TEMPEST, provides an outflow solution based on only one input: the magnetic field strength as a function of height above the photosphere. It uses correlations found in ZEPHYR between the magnetic field strength at the source surface and the temperature profile of the outflow solution to compute the wind speed profile based on the increased gas pressure from turbulent heating. With this initial solution, TEMPEST then adds in the Alfven wave pressure term to the modified Parker equation and iterates to find a stable solution for the wind speed. This code, therefore, can make predictions of the wind speeds that will be observed at 1 AU based on extrapolations from magnetogram data, providing a useful tool for empirical forecasting of the sol! ar wind.

The nature of micro CMEs within coronal holes

NASA Astrophysics Data System (ADS)

Bothmer, Volker; Nistico, Giuseppe; Zimbardo, Gaetano; Patsourakos, Spiros; Bosman, Eckhard

Whilst investigating the origin and characteristics of coronal jets and large-scale CMEs identi-fied in data from the SECCHI (Sun Earth Connection Coronal and Heliospheric Investigation) instrument suites on board the two STEREO satellites, we discovered transient events that originated in the low corona with a morphology resembling that of typical three-part struc-tured coronal mass ejections (CMEs). However, the CMEs occurred on considerably smaller spatial scales. In this presentation we show evidence for the existence of small-scale CMEs from inside coronal holes and present quantitative estimates of their speeds and masses. We interprete the origin and evolution of micro CMEs as a natural consequence of the emergence of small-scale magnetic bipoles related to the Sun's ever changing photospheric magnetic flux on various scales and their interactions with the ambient plasma and magnetic field. The analysis of CMEs is performed within the framework of the EU Erasmus and FP7 SOTERIA projects.

Magnetic Nulls and Super-radial Expansion in the Solar Corona

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gibson, Sarah E.; Dalmasse, Kevin; Tomczyk, Steven

Magnetic fields in the Sun’s outer atmosphere—the corona—control both solar-wind acceleration and the dynamics of solar eruptions. We present the first clear observational evidence of coronal magnetic nulls in off-limb linearly polarized observations of pseudostreamers, taken by the Coronal Multichannel Polarimeter (CoMP) telescope. These nulls represent regions where magnetic reconnection is likely to act as a catalyst for solar activity. CoMP linear-polarization observations also provide an independent, coronal proxy for magnetic expansion into the solar wind, a quantity often used to parameterize and predict the solar wind speed at Earth. We introduce a new method for explicitly calculating expansion factorsmore » from CoMP coronal linear-polarization observations, which does not require photospheric extrapolations. We conclude that linearly polarized light is a powerful new diagnostic of critical coronal magnetic topologies and the expanding magnetic flux tubes that channel the solar wind.« less

Magnetic Nulls and Super-Radial Expansion in the Solar Corona

NASA Technical Reports Server (NTRS)

Gibson, Sarah E.; Dalmasse, Kevin; Rachmeler, Laurel A.; De Rosa, Marc L.; Tomczyk, Steven; De Toma, Giuliana; Burkepile, Joan; Galloy, Michael

2017-01-01

Magnetic fields in the Sun's outer atmosphere, the corona, control both solar-wind acceleration and the dynamics of solar eruptions. We present the first clear observational evidence of coronal magnetic nulls in off-limb linearly polarized observations of pseudostreamers, taken by the Coronal Multichannel Polarimeter (CoMP) telescope. These nulls represent regions where magnetic reconnection is likely to act as a catalyst for solar activity.CoMP linear-polarization observations also provide an independent, coronal proxy for magnetic expansion into the solar wind, a quantity often used to parameterize and predict the solar wind speed at Earth. We introduce a new method for explicitly calculating expansion factors from CoMP coronal linear-polarization observations, which does not require photospheric extrapolations. We conclude that linearly polarized light is a powerful new diagnostic of critical coronal magnetic topologies and the expanding magnetic flux tubes that channel the solar wind.

Relating magnetic reconnection to coronal heating

PubMed Central

Longcope, D. W.; Tarr, L. A.

2015-01-01

It is clear that the solar corona is being heated and that coronal magnetic fields undergo reconnection all the time. Here we attempt to show that these two facts are related—i.e. coronal reconnection generates heat. This attempt must address the fact that topological change of field lines does not automatically generate heat. We present one case of flux emergence where we have measured the rate of coronal magnetic reconnection and the rate of energy dissipation in the corona. The ratio of these two, , is a current comparable to the amount of current expected to flow along the boundary separating the emerged flux from the pre-existing flux overlying it. We can generalize this relation to the overall corona in quiet Sun or in active regions. Doing so yields estimates for the contribution to coronal heating from magnetic reconnection. These estimated rates are comparable to the amount required to maintain the corona at its observed temperature. PMID:25897089

The Magnetic Evolution of Coronal Hole Bright Points

NASA Astrophysics Data System (ADS)

He, Y.; Muglach, K.

2017-12-01

Space weather refers to the state of the heliosphere and the geospace environment that are caused primarily by solar activity. Coronal mass ejections and flares originate in active regions and filaments close to the solar surface and can cause geomagnetic storms and solar energetic particles events, which can damage both spacecraft and ground-based systems that are critical for society's well-being. Coronal bright points are small-scale magnetic regions on the sun that seem to be similar to active regions, but are about an order of magnitude smaller. Due to their shorter lifetime, the complete evolutionary cycle of these mini active regions can be studied, from the time they appear in extreme-ultraviolet (EUV) images to the time they fade. We are using data from the Solar Dynamics Observatory (SDO) to study both the coronal EUV flux and the photospheric magnetic field and compare them to activities of the coronal bright point.

Coronal Magnetism and Forward Solarsoft Idl Package

NASA Astrophysics Data System (ADS)

Gibson, S. E.

2014-12-01

The FORWARD suite of Solar Soft IDL codes is a community resource for model-data comparison, with a particular emphasis on analyzing coronal magnetic fields. FORWARD may be used both to synthesize a broad range of coronal observables, and to access and compare to existing data. FORWARD works with numerical model datacubes, interfaces with the web-served Predictive Science Inc MAS simulation datacubes and the Solar Soft IDL Potential Field Source Surface (PFSS) package, and also includes several analytic models (more can be added). It connects to the Virtual Solar Observatory and other web-served observations to download data in a format directly comparable to model predictions. It utilizes the CHIANTI database in modeling UV/EUV lines, and links to the CLE polarimetry synthesis code for forbidden coronal lines. FORWARD enables "forward-fitting" of specific observations, and helps to build intuition into how the physical properties of coronal magnetic structures translate to observable properties.

Electrical energy sources for organic synthesis on the early earth

NASA Technical Reports Server (NTRS)

Chyba, Christopher; Sagan, Carl

1991-01-01

It is pointed out that much of the contemporary origin-of-life research uses the original estimates of Miller and Urey (1959) for terrestrial energy dissipation by lightning and coronal discharges being equal to 2 x 10 to the 19th J/yr and 6 x 10 to the 19th J/yr, respectively. However, data from experiments that provide analogues to naturally-occurring lightning and coronal discharges indicate that lightning energy yields for organic synthesis (nmole/J) are about one order of magnitude higher than the coronal discharge yields. This suggests that, on early earth, organic production by lightning may have dominated that due to coronal emission. New values are recommended for lightning and coronal discharge dissipation rates on the early earth, 1 x 10 to the 18th J/yr and 5 x 10 to the 17th J/yr, respectively.

Solar burst precursors and energy build-up at microwave wavelengths

NASA Technical Reports Server (NTRS)

Lang, Kenneth R.; Wilson, Robert F.

1986-01-01

We summarize high-resolution microwave observations (VLA) of heating and magnetic triggering in coronal loops. Magnetic changes that precede solar eruptions on time scales of tens of minutes involve primarily emerging coronal loops and the interaction of two or more loops. Thermal cyclotron lines have been detected in coronal loops, suggesting the presence of hot current sheets that enhance emission from relatively thin layers of enhanced temperature and constant magnetic field. These current sheets may play a role in the excitation of solar bursts. A filament-associated source with a high brightness temperature and steep radiation spectrum occurs above a region of apparently weak photospheric field. This source might be attributed to currents that enhance coronal magnetic fields. Compact (phi=5 sec) transient sources with lifetimes of 30 to 60 minutes have also been detected in regions of apparently weak photospheric field. We conclude by comparing VLA observations of coronal loops with simultaneous SMM-XRP observations.

Solar burst precursors and energy build-up at microwave wavelengths

NASA Astrophysics Data System (ADS)

Lang, Kenneth R.; Wilson, Robert F.

We summarize high-resolution microwave observations (VLA) of heating and magnetic triggering in coronal loops. Magnetic changes that precede solar eruptions on time scales of tens of minutes involve primarily emerging coronal loops and the interaction of two or more loops. Thermal cyclotron lines have been detected in coronal loops, suggesting the presence of hot current sheets that enhance emission from relatively thin layers of enhanced temperature and constant magnetic field. These current sheets may play a role in the excitation of solar bursts. A filament-associated source with a high brightness temperature and steep radiation spectrum occurs above a region of apparently weak photospheric field. This source might be attributed to currents that enhance coronal magnetic fields. Compact (phi=5 sec) transient sources with lifetimes of 30 to 60 minutes have also been detected in regions of apparently weak photospheric field. We conclude by comparing VLA observations of coronal loops with simultaneous SMM-XRP observations.

Propagation and Dissipation of MHD Waves in Coronal Holes

NASA Astrophysics Data System (ADS)

Dwivedi, B. N.

2006-11-01

bholadwivedi@gmail.com In view of the landmark result on the solar wind outflow, starting between 5 Mm and 20 Mm above the photosphere in magnetic funnels, we investigate the propagation and dissipation of MHD waves in coronal holes. We underline the importance of Alfvén wave dissipation in the magnetic funnels through the viscous and resistive plasma. Our results show that Alfvén waves are one of the primary energy sources in the innermost part of coronal holes where the solar wind outflow starts. We also consider compressive viscosity and thermal conductivity to study the propagation and dissipation of long period slow longitudinal MHD waves in polar coronal holes. We discuss their likely role in the line profile narrowing, and in the energy budget for coronal holes and the solar wind. We compare the contribution of longitudinal MHD waves with high frequency Alfvén waves.

Marketing the Uniqueness of Small Towns. Revised.

ERIC Educational Resources Information Center

Dunn, Douglas; Hogg, David H.

The key to marketing a town is determining and promoting the town's "differential advantage" or uniqueness that would make people want to visit or live there. Exercises to help communities gain important insights into the town's competitive edge include a brainstorming session with knowledgeable community members, a visitor…

Evidence that magnetic energy shedding in solar filament eruptions is the drive in accompanying flares and coronal mass ejections

NASA Technical Reports Server (NTRS)

Moore, Ronald L.

1988-01-01

The dependence of the magnetic energy on the field expansion and untwisting of the flux tube in which an erupting solar filament is embedded has been determined in order to evaluate the energy decrease in the erupting flux tube. Magnetic energy shedding by the filament-field eruption is found to be the driving mechanism in both filament-eruption flares and coronal mass ejections. Confined filament-eruption flares, filament-eruption flares with sprays and coronal mass ejections, and coronal mass ejections from quiescent filament eruptions are all shown to be similar types of events.

EUV Coronal Waves: Atmospheric and Heliospheric Connections and Energetics

NASA Astrophysics Data System (ADS)

Patsourakos, S.

2015-12-01

Since their discovery in late 90's by EIT on SOHO, the study EUV coronal waves has been a fascinating andfrequently strongly debated research area. While it seems as ifan overall consensus has been reached about the nurture and nature of this phenomenon,there are still several important questions regarding EUV waves. By focusing on the most recentobservations, we will hereby present our current understanding about the nurture and nature of EUV waves,discuss their connections with other atmospheric and heliospheric phenomena (e.g.,flares and CMEs, Moreton waves, coronal shocks, coronal oscillations, SEP events) and finallyassess their possible energetic contribution to the overall budget of relatederuptive phenomena.

Solar activity during Skylab: Its distribution and relation to coronal holes

NASA Technical Reports Server (NTRS)

Speich, D. M.; Smith, J. B., Jr.; Wilson, R. M.; Mcintosh, P. S.

1978-01-01

Solar active regions observed during the period of Skylab observations (May 1973-February 1974) were examined for properties that varied systematically with location on the sun, particularly with respect to the location of coronal holes. Approximately 90 percent of the optical and X-ray flare activity occurred in one solar hemisphere (136-315 heliographic degrees longitude). Active regions within 20 heliographic degrees of coronal holes were below average in lifetimes, flare production, and magnetic complexity. Histograms of solar flares as a function of solar longitude were aligned with H alpha synoptic charts on which active region serial numbers and coronal hole boundaries were added.

Non-adversarial justice and the coroner's court: a proposed therapeutic, restorative, problem-solving model.

PubMed

King, Michael S

2008-12-01

Increasingly courts are using new approaches that promote a more comprehensive resolution of legal problems, minimise any negative effects that legal processes have on participant wellbeing and/or that use legal processes to promote participant wellbeing. Therapeutic jurisprudence, restorative justice, mediation and problem-solving courts are examples. This article suggests a model for the use of these processes in the coroner's court to minimise negative effects of coroner's court processes on the bereaved and to promote a more comprehensive resolution of matters at issue, including the determination of the cause of death and the public health and safety promotion role of the coroner.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chitta, L. P.; Peter, H.; Solanki, S. K.

How and where are coronal loops rooted in the solar lower atmosphere? The details of the magnetic environment and its evolution at the footpoints of coronal loops are crucial to understanding the processes of mass and energy supply to the solar corona. To address the above question, we use high-resolution line-of-sight magnetic field data from the Imaging Magnetograph eXperiment instrument on the Sunrise balloon-borne observatory and coronal observations from the Atmospheric Imaging Assembly onboard the Solar Dynamics Observatory of an emerging active region. We find that the coronal loops are often rooted at the locations with minor small-scale but persistentmore » opposite-polarity magnetic elements very close to the larger dominant polarity. These opposite-polarity small-scale elements continually interact with the dominant polarity underlying the coronal loop through flux cancellation. At these locations we detect small inverse Y-shaped jets in chromospheric Ca ii H images obtained from the Sunrise Filter Imager during the flux cancellation. Our results indicate that magnetic flux cancellation and reconnection at the base of coronal loops due to mixed polarity fields might be a crucial feature for the supply of mass and energy into the corona.« less

Understanding the rotation of coronal holes

NASA Astrophysics Data System (ADS)

Wang, Y.-M.; Sheeley, N. R., Jr.

1993-09-01

In an earlier study we found that the rotation of coronal holes could be understood on the basis of a nearly current-free coronal field, with the holes representing open magnetic regions. In this paper we illustrate the model by focusing on the case of CH1, the rigidly rotating boot-shaped hole observed by Skylab. We show that the interaction between the polar fields and the flux associated with active regions produces distortions in the coronal field configuration and thus in the polar-hole boundaries; these distortions corotate with the perturbing nonaxisymmetric flux. In the case of CH1, positive-polarity field lines in the northern hemisphere 'collided' with like-polarity field lines fanning out from a decaying active region complex located just below the equator, producing a midlatitude corridor of open field lines rotating at the rate of the active region complex. Sheared coronal holes result when nonaxisymmetric flux is present at high latitudes, or equivalently, when the photospheric neutral line extends to high latitudes. We demonstrate how a small active region, rotating at the local photospheric rate, can drift through a rigidly rotating hole like CH1. Finally, we discuss the role of field-line reconnection in maintaining a quasi-potential coronal configuration.

Mode Conversion of a Solar Extreme-ultraviolet Wave over a Coronal Cavity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zong, Weiguo; Dai, Yu, E-mail: ydai@nju.edu.cn

2017-01-10

We report on observations of an extreme-ultraviolet (EUV) wave event in the Sun on 2011 January 13 by Solar Terrestrial Relations Observatory and Solar Dynamics Observatory in quadrature. Both the trailing edge and the leading edge of the EUV wave front in the north direction are reliably traced, revealing generally compatible propagation velocities in both perspectives and a velocity ratio of about 1/3. When the wave front encounters a coronal cavity near the northern polar coronal hole, the trailing edge of the front stops while its leading edge just shows a small gap and extends over the cavity, meanwhile gettingmore » significantly decelerated but intensified. We propose that the trailing edge and the leading edge of the northward propagating wave front correspond to a non-wave coronal mass ejection component and a fast-mode magnetohydrodynamic wave component, respectively. The interaction of the fast-mode wave and the coronal cavity may involve a mode conversion process, through which part of the fast-mode wave is converted to a slow-mode wave that is trapped along the magnetic field lines. This scenario can reasonably account for the unusual behavior of the wave front over the coronal cavity.« less

On the Role of Interchange Reconnection in the Generation of the Slow Solar Wind

NASA Astrophysics Data System (ADS)

Edmondson, J. K.

2012-11-01

The heating of the solar corona and therefore the generation of the solar wind, remain an active area of solar and heliophysics research. Several decades of in situ solar wind plasma observations have revealed a rich bimodal solar wind structure, well correlated with coronal magnetic field activity. Therefore, the reconnection processes associated with the large-scale dynamics of the corona likely play a major role in the generation of the slow solar wind flow regime. In order to elucidate the relationship between reconnection-driven coronal magnetic field structure and dynamics and the generation of the slow solar wind, this paper reviews the observations and phenomenology of the solar wind and coronal magnetic field structure. The geometry and topology of nested flux systems, and the (interchange) reconnection process, in the context of coronal physics is then explained. Once these foundations are laid out, the paper summarizes several fully dynamic, 3D MHD calculations of the global coronal system. Finally, the results of these calculations justify a number of important implications and conclusions on the role of reconnection in the structural dynamics of the coronal magnetic field and the generation of the solar wind.

NEW OBSERVATION OF FAILED FILAMENT ERUPTIONS: THE INFLUENCE OF ASYMMETRIC CORONAL BACKGROUND FIELDS ON SOLAR ERUPTIONS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Y.; Xu, Z.; Su, J.

2009-05-01

Failed filament eruptions not associated with a coronal mass ejection (CME) have been observed and reported as evidence for solar coronal field confinement on erupting flux ropes. In those events, each filament eventually returns to its origin on the solar surface. In this Letter, a new observation of two failed filament eruptions is reported which indicates that the mass of a confined filament can be ejected to places far from the original filament channel. The jetlike mass motions in the two failed filament eruptions are thought to be due to the asymmetry of the background coronal magnetic fields with respectmore » to the locations of the filament channels. The asymmetry of the coronal fields is confirmed by an extrapolation based on a potential field model. The obvious imbalance between the positive and negative magnetic flux (with a ratio of 1:3) in the bipolar active region is thought to be the direct cause of the formation of the asymmetric coronal fields. We think that the asymmetry of the background fields can not only influence the trajectories of ejecta, but also provide a relatively stronger confinement for flux rope eruptions than the symmetric background fields do.« less

Microfilament-Eruption Mechanism for Solar Spicules

NASA Technical Reports Server (NTRS)

Sterling, Alphonse C.; Moore, Ronald L.

2017-01-01

Recent studies indicate that solar coronal jets result from eruption of small-scale filaments, or "minifilaments" (Sterling et al. 2015, Nature, 523, 437; Panesar et al. ApJL, 832L, 7). In many aspects, these coronal jets appear to be small-scale versions of long-recognized large-scale solar eruptions that are often accompanied by eruption of a large-scale filament and that produce solar flares and coronal mass ejections (CMEs). In coronal jets, a jet-base bright point (JBP) that is often observed to accompany the jet and that sits on the magnetic neutral line from which the minifilament erupts, corresponds to the solar flare of larger-scale eruptions that occurs at the neutral line from which the large-scale filament erupts. Large-scale eruptions are relatively uncommon (approximately 1 per day) and occur with relatively large-scale erupting filaments (approximately 10 (sup 5) kilometers long). Coronal jets are more common (approximately 100s per day), but occur from erupting minifilaments of smaller size (approximately 10 (sup 4) kilometers long). It is known that solar spicules are much more frequent (many millions per day) than coronal jets. Just as coronal jets are small-scale versions of large-scale eruptions, here we suggest that solar spicules might in turn be small-scale versions of coronal jets; we postulate that the spicules are produced by eruptions of "microfilaments" of length comparable to the width of observed spicules (approximately 300 kilometers). A plot of the estimated number of the three respective phenomena (flares/CMEs, coronal jets, and spicules) occurring on the Sun at a given time, against the average sizes of erupting filaments, minifilaments, and the putative microfilaments, results in a size distribution that can be fitted with a power-law within the estimated uncertainties. The counterparts of the flares of large-scale eruptions and the JBPs of jets might be weak, pervasive, transient brightenings observed in Hinode/CaII images, and the production of spicules by microfilament eruptions might explain why spicules spin, as do coronal jets. The expected small-scale neutral lines from which the microfilaments would be expected to erupt would be difficult to detect reliably with current instrumentation, but might be apparent with instrumentation of the near future. A full report on this work appears in Sterling and Moore 2016, ApJL, 829, L9.

FGFR2c-mediated ERK-MAPK activity regulates coronal suture development

PubMed Central

Pfaff, Miles J.; Xue, Ke; Li, Li; Horowitz, Mark C.; Steinbacher, Derek M.; Eswarakumar, Jacob V.P.

2017-01-01

Fibroblast growth factor receptor 2 (FGFR2) signaling is critical for proper craniofacial development. A gain-of-function mutation in the 2c splice variant of the receptor’s gene is associated with Crouzon syndrome, which is characterized by craniosynostosis, the premature fusion of one or more of the cranial vault sutures, leading to craniofacial maldevelopment. Insight into the molecular mechanism of craniosynostosis has identified the ERK-MAPK signaling cascade as a critical regulator of suture patency. The aim of this study is to investigate the role of FGFR2c-induced ERK-MAPK activation in the regulation of coronal suture development. Loss-of-function and gain-of-function Fgfr2c mutant mice have overlapping phenotypes, including coronal synostosis and craniofacial dysmorphia. In vivo analysis of coronal sutures in loss-of-function and gain-of-function models demonstrated fundamentally different pathogenesis underlying coronal suture synostosis. Calvarial osteoblasts from gain-of-function mice demonstrated enhanced osteoblastic function and maturation with concomitant increase in ERK-MAPK activation. In vitro inhibition with the ERK protein inhibitor U0126 mitigated ERK protein activation levels with a concomitant reduction in alkaline phosphatase activity. This study identifies FGFR2c-mediated ERK-MAPK signaling as a key mediator of craniofacial growth and coronal suture development. Furthermore, our results solve the apparent paradox between loss-of-function and gain-of-function FGFR2c mutants with respect to coronal suture synostosis. PMID:27034231

A Universal Model for Solar Eruptions

NASA Technical Reports Server (NTRS)

Wyper, Peter F.; Antiochos, Spiro K.; Devore, C. Richard

2017-01-01

Magnetically driven eruptions on the Sun, from stellar-scale coronal mass ejections1 to small-scale coronal X-ray and extreme-ultraviolet jets, have frequently been observed to involve the ejection of the highly stressed magnetic flux of a filament. Theoretically, these two phenomena have been thought to arise through very different mechanisms: coronal mass ejections from an ideal (non-dissipative) process, whereby the energy release does not require a change in the magnetic topology, as in the kink or torus instability; and coronal jets from a resistive process, involving magnetic reconnection. However, it was recently concluded from new observations that all coronal jets are driven by filament ejection, just like large mass ejections. This suggests that the two phenomena have physically identical origin and hence that a single mechanism may be responsible, that is, either mass ejections arise from reconnection, or jets arise from an ideal instability. Here we report simulations of a coronal jet driven by filament ejection, whereby a region of highly sheared magnetic field near the solar surface becomes unstable and erupts. The results show that magnetic reconnection causes the energy release via 'magnetic breakout', a positive feedback mechanism between filament ejection and reconnection. We conclude that if coronal mass ejections and jets are indeed of physically identical origin (although on different spatial scales) then magnetic reconnection (rather than an ideal process) must also underlie mass ejections, and that magnetic breakout is a universal model for solar eruptions.

Evidence for Precursors of the Coronal Hole Jets in Solar Bright Points

NASA Astrophysics Data System (ADS)

Bagashvili, Salome R.; Shergelashvili, Bidzina M.; Japaridze, Darejan R.; Kukhianidze, Vasil; Poedts, Stefaan; Zaqarashvili, Teimuraz V.; Khodachenko, Maxim L.; De Causmaecker, Patrick

2018-03-01

A set of 23 observations of coronal jet events that occurred in coronal bright points has been analyzed. The focus was on the temporal evolution of the mean brightness before and during coronal jet events. In the absolute majority of the cases either single or recurrent coronal jets (CJs) were preceded by slight precursor disturbances observed in the mean intensity curves. The key conclusion is that we were able to detect quasi-periodical oscillations with characteristic periods from sub-minute up to 3–4 minute values in the bright point brightness that precedes the jets. Our basic claim is that along with the conventionally accepted scenario of bright-point evolution through new magnetic flux emergence and its reconnection with the initial structure of the bright point and the coronal hole, certain magnetohydrodynamic (MHD) oscillatory and wavelike motions can be excited and these can take an important place in the observed dynamics. These quasi-oscillatory phenomena might play the role of links between different epochs of the coronal jet ignition and evolution. They can be an indication of the MHD wave excitation processes due to the system entropy variations, density variations, or shear flows. It is very likely a sharp outflow velocity transverse gradients at the edges between the open and closed field line regions. We suppose that magnetic reconnections can be the source of MHD waves due to impulsive generation or rapid temperature variations, and shear flow driven nonmodel MHD wave evolution (self-heating and/or overreflection mechanisms).

Coronal rain in magnetic bipolar weak fields

NASA Astrophysics Data System (ADS)

Xia, C.; Keppens, R.; Fang, X.

2017-07-01

Aims: We intend to investigate the underlying physics for the coronal rain phenomenon in a representative bipolar magnetic field, including the formation and the dynamics of coronal rain blobs. Methods: With the MPI-AMRVAC code, we performed three dimensional radiative magnetohydrodynamic (MHD) simulation with strong heating localized on footpoints of magnetic loops after a relaxation to quiet solar atmosphere. Results: Progressive cooling and in-situ condensation starts at the loop top due to radiative thermal instability. The first large-scale condensation on the loop top suffers Rayleigh-Taylor instability and becomes fragmented into smaller blobs. The blobs fall vertically dragging magnetic loops until they reach low-β regions and start to fall along the loops from loop top to loop footpoints. A statistic study of the coronal rain blobs finds that small blobs with masses of less than 1010 g dominate the population. When blobs fall to lower regions along the magnetic loops, they are stretched and develop a non-uniform velocity pattern with an anti-parallel shearing pattern seen to develop along the central axis of the blobs. Synthetic images of simulated coronal rain with Solar Dynamics Observatory Atmospheric Imaging Assembly well resemble real observations presenting dark falling clumps in hot channels and bright rain blobs in a cool channel. We also find density inhomogeneities during a coronal rain "shower", which reflects the observed multi-stranded nature of coronal rain. Movies associated to Figs. 3 and 7 are available at http://www.aanda.org

Influence of the remaining coronal structure on the resistance of teeth with intraradicular retainer.

PubMed

Pereira, Jefferson Ricardo; Neto, Tatiany de Mendonça; Porto, Vinícius de Carvalho; Pegoraro, Luiz Fernando; do Valle, Accácio Lins

2005-01-01

The aim of this study was to compare the resistance of endodontically treated teeth with intraradicular retainer different amounts of remaining coronal structure. Fifty freshly extracted maxillary canines were endodontically treated and randomly assigned to five groups (n=10), as follows: group 1 (control) = teeth with custom cast post and core; group 2 = teeth without remaining coronal structure; group 3, 4 and 5 = teeth with 1 mm, 2 mm and 3 mm of remaining coronal structure, respectively. All specimens in groups 2 to 5 were restored with prefabricated post and resin core. The teeth were embedded in acrylic resin and the fracture strength was measured on a universal testing machine at 45 degrees to the long axis of the tooth until failure. Data were analyzed statistically by one-way analysis of variance and Tukey's test. There was no significant differences (p>0.05) between the control group and group 2, and between groups 3, 4 and 5 (p>0.05). Control group and group 2 had significantly higher resistance strength than groups 3, 4 and 5 (p<0.00001). The findings of this study showed that teeth without remaining coronal structure had significantly higher fracture strength than those with remaining coronal structure (1 mm, 2 mm and 3 mm). When the dental crown was not completely removed, the amount of remaining coronal dentin did not significantly affect the fracture strength of endodontically treated teeth with intraradicular retainer.

Observations and Modeling of Transition Region and Coronal Heating Associated with Spicules

NASA Astrophysics Data System (ADS)

De Pontieu, B.; Martinez-Sykora, J.; De Moortel, I.; Chintzoglou, G.; McIntosh, S. W.

2017-12-01

Spicules have been proposed as significant contributorsto the coronal energy and mass balance. While previous observationshave provided a glimpse of short-lived transient brightenings in thecorona that are associated with spicules, these observations have beencontested and are the subject of a vigorous debate both on the modelingand the observational side so that it remains unclear whether plasmais heated to coronal temperatures in association with spicules. We use high-resolution observations of the chromosphere and transition region with the Interface Region Imaging Spectrograph (IRIS) and ofthe corona with the Atmospheric Imaging Assembly (AIA) onboard theSolar Dynamics Observatory (SDO) to show evidence of the formation of coronal structures as a result of spicular mass ejections andheating of plasma to transition region and coronaltemperatures. Our observations suggest that a significant fraction of the highly dynamic loop fan environment associated with plage regions may be the result of the formation of such new coronal strands, a process that previously had been interpreted as the propagation of transient propagating coronal disturbances (PCD)s. Our observationsare supported by 2.5D radiative MHD simulations that show heating tocoronal temperatures in association with spicules. Our results suggest that heating and strong flows play an important role in maintaining the substructure of loop fans, in addition to the waves that permeate this low coronal environment. Our models also matches observations ofTR counterparts of spicules and provides an elegant explanation forthe high apparent speeds of these "network jets".

FGFR2c-mediated ERK-MAPK activity regulates coronal suture development.

PubMed

Pfaff, Miles J; Xue, Ke; Li, Li; Horowitz, Mark C; Steinbacher, Derek M; Eswarakumar, Jacob V P

2016-07-15

Fibroblast growth factor receptor 2 (FGFR2) signaling is critical for proper craniofacial development. A gain-of-function mutation in the 2c splice variant of the receptor's gene is associated with Crouzon syndrome, which is characterized by craniosynostosis, the premature fusion of one or more of the cranial vault sutures, leading to craniofacial maldevelopment. Insight into the molecular mechanism of craniosynostosis has identified the ERK-MAPK signaling cascade as a critical regulator of suture patency. The aim of this study is to investigate the role of FGFR2c-induced ERK-MAPK activation in the regulation of coronal suture development. Loss-of-function and gain-of-function Fgfr2c mutant mice have overlapping phenotypes, including coronal synostosis and craniofacial dysmorphia. In vivo analysis of coronal sutures in loss-of-function and gain-of-function models demonstrated fundamentally different pathogenesis underlying coronal suture synostosis. Calvarial osteoblasts from gain-of-function mice demonstrated enhanced osteoblastic function and maturation with concomitant increase in ERK-MAPK activation. In vitro inhibition with the ERK protein inhibitor U0126 mitigated ERK protein activation levels with a concomitant reduction in alkaline phosphatase activity. This study identifies FGFR2c-mediated ERK-MAPK signaling as a key mediator of craniofacial growth and coronal suture development. Furthermore, our results solve the apparent paradox between loss-of-function and gain-of-function FGFR2c mutants with respect to coronal suture synostosis. Copyright © 2016 Elsevier Inc. All rights reserved.

Magnetic Flux Cancelation as the Trigger of Solar Coronal Jets in Coronal Holes

NASA Astrophysics Data System (ADS)

Panesar, Navdeep K.; Sterling, Alphonse C.; Moore, Ronald L.

2018-02-01

We investigate in detail the magnetic cause of minifilament eruptions that drive coronal-hole jets. We study 13 random on-disk coronal-hole jet eruptions, using high-resolution X-ray images from the Hinode/X-ray telescope(XRT), EUV images from the Solar Dynamics Observatory (SDO)/Atmospheric Imaging Assembly (AIA), and magnetograms from the SDO/Helioseismic and Magnetic Imager (HMI). For all 13 events, we track the evolution of the jet-base region and find that a minifilament of cool (transition-region-temperature) plasma is present prior to each jet eruption. HMI magnetograms show that the minifilaments reside along a magnetic neutral line between majority-polarity and minority-polarity magnetic flux patches. These patches converge and cancel with each other, with an average cancelation rate of ∼0.6 × 1018 Mx hr‑1 for all 13 jets. Persistent flux cancelation at the neutral line eventually destabilizes the minifilament field, which erupts outward and produces the jet spire. Thus, we find that all 13 coronal-hole-jet-driving minifilament eruptions are triggered by flux cancelation at the neutral line. These results are in agreement with our recent findings for quiet-region jets, where flux cancelation at the underlying neutral line triggers the minifilament eruption that drives each jet. Thus, from that study of quiet-Sun jets and this study of coronal-hole jets, we conclude that flux cancelation is the main candidate for triggering quiet-region and coronal-hole jets.

Reconnection-Driven Coronal-Hole Jets with Gravity and Solar Wind

NASA Technical Reports Server (NTRS)

Karpen, J. T.; Devore, C. R.; Antiochos, S. K.; Pariat, E.

2017-01-01

Coronal-hole jets occur ubiquitously in the Sun's coronal holes, at EUV and X-ray bright points associated with intrusions of minority magnetic polarity. The embedded-bipole model for these jets posits that they are driven by explosive, fast reconnection between the stressed closed field of the embedded bipole and the open field of the surrounding coronal hole. Previous numerical studies in Cartesian geometry, assuming uniform ambient magnetic field and plasma while neglecting gravity and solar wind, demonstrated that the model is robust and can produce jet-like events in simple configurations. We have extended these investigations by including spherical geometry,gravity, and solar wind in a nonuniform, coronal hole-like ambient atmosphere. Our simulations confirm that the jet is initiated by the onset of a kink-like instability of the internal closed field, which induces a burst of reconnection between the closed and external open field, launching a helical jet. Our new results demonstrate that the jet propagation is sustained through the outer corona, in the form of a traveling nonlinear Alfven wave front trailed by slower-moving plasma density enhancements that are compressed and accelerated by the wave. This finding agrees well with observations of white-light coronal-hole jets, and can explain microstreams and torsional Alfven waves detected in situ in the solar wind. We also use our numerical results to deduce scaling relationships between properties of the coronal source region and the characteristics of the resulting jet, which can be tested against observations.

Determination of Heavy Metals in Alpinia oxyphylla Miq. Collected from Different Cultivation Regions

PubMed Central

Fu, Yurong; Lai, Weiyong; Zhang, Junqing

2016-01-01

20 batches of Alpinia oxyphylla Miq. were collected from Yunnan, Guangdong, Guangxi, and Hainan province in China. The contents of heavy metals of As, Hg, Pb, Cd, and Cu were determined and compared. The results indicated that geographical source might be a major factor to influence the contents of heavy metals of arsenic (As), mercury (Hg), lead (Pb), cadmium (Cd), and copper (Cu) in Alpinia oxyphylla Miq. Compared to the criteria of heavy metals, the contents of As, Hg, Pb, and Cd in almost all the samples were in accordance with The Green Trade Standards. The contents of Cu were higher than the criteria for heavy metals except the samples from Changxing town, Qiongzhong county, Maoyang town, Qiongzhong county, Wupo town, Tunchang county, and Nanlv town, Tunchang county, in Hainan province. The best cultivation regions of Alpinia oxyphylla Miq. were from Changxing town, Qiongzhong county, Maoyang town, Qiongzhong county, Wupo town, Tunchang county, and Nanlv town, Tunchang county, in Hainan province. This research would provide the scientific basis for quality control and standardization of Alpinia oxyphylla Miq. PMID:27293963

A Survey of Coronal Dimmings and EIT Wave Transients

NASA Technical Reports Server (NTRS)

Thompson, Barbara J.

2003-01-01

We present the results of a comprehensive catalog of EIT wave transients and coronal dimmings. We will compiled a set of more than 170 events, and we present strong evidence for the association of the co-development of coronal dimmings and EIT waves. Both limb and disk events are included in this study. We also include the speeds, locations, and associated flare timing in this study.

Dynamical behaviour in coronal loops

NASA Technical Reports Server (NTRS)

Haisch, Bernhard M.

1986-01-01

Rapid variability has been found in two active region coronal loops observed by the X-ray Polychromator (XRP) and the Hard X-ray Imaging Spectrometer (HXIS) onboard the Solar Maximum Mission (SMM). There appear to be surprisingly few observations of the short-time scale behavior of hot loops, and the evidence presented herein lends support to the hypothesis that coronal heating may be impulsive and driven by flaring.

Dynamical behaviour in coronal loops

NASA Astrophysics Data System (ADS)

Haisch, Bernhard M.

Rapid variability has been found in two active region coronal loops observed by the X-ray Polychromator (XRP) and the Hard X-ray Imaging Spectrometer (HXIS) onboard the Solar Maximum Mission (SMM). There appear to be surprisingly few observations of the short-time scale behavior of hot loops, and the evidence presented herein lends support to the hypothesis that coronal heating may be impulsive and driven by flaring.

Radiological factors affecting post-operative global coronal balance in Lenke 5 C scoliosis.

PubMed

Shetty, Ajoy Prasad; Suresh, Subramani; Aiyer, Siddharth N; Kanna, Rishi; Rajasekaran, Shanmuganathan

2017-12-01

Lenke 5 C curves are frequently associated with clinically and radiological coronal imbalance. Appropriate selection of proximal and distal levels of fusion is essential to ensure good coronal balance (CB). We aimed to evaluate radiological factors associated with (I) global CB in the early post-operative period; (II) late decompensation of CB; and (III) favourable spontaneous correction of CB on long term follow up. Twenty-three Lenke type 5C scoliosis cases treated with selective posterior lumbar instrumentation were retrospectively evaluated. Pre-operative, early post-operative and late post-operative (>2 years) whole length radiographs were analysed. Cobb's angle, lumbar lordosis, coronal imbalance, lower instrumented vertebra (LIV) tilt and translation and upper instrumented vertebra (UIV) tilt and translation were measured. The proximal and distal fusion levels were noted and correlated with post-operative CB. There were 21 females and 2 males with a mean follow up of 36 months. The mean pre-operative cobb angle was 55°±13.26°, which corrected to 14.7°±8.84° and was maintained on follow up. Eight patients had early post-operative coronal imbalance with spontaneous resolution seen in six cases on long term follow-up. At final follow-up, four cases had coronal imbalance (persistent imbalance since early post-operative period =2; late decompensation =2). In cases with early imbalance 5/8 cases had a pre-operative LIV tilt of ≥25°. All four patients with coronal imbalance at final follow-up had pre-operative LIV tilt ≥25°. Radiographic parameters which correlated with post-operative coronal imbalance were pre-operative LIV tilt (r=0.64, P=0.001), pre-operative LIV translation (r=0.696, P<0.001), pre-operative UIV translation (r=0.44, P=0.030), post-operative LIV tilt (r=0.804, P<0.001), and post-operative UIV tilt (r=0.62, P=0.001). In Lenke 5C scoliosis, a pre-operative LIV tilt ≥25° significantly correlates with post-operative global coronal imbalance. Increasing UIV tilt may be a factor that accounts for improvement of CB in late follow-up period.

Radiological factors affecting post-operative global coronal balance in Lenke 5 C scoliosis

PubMed Central

Suresh, Subramani; Aiyer, Siddharth N.; Kanna, Rishi; Rajasekaran, Shanmuganathan

2017-01-01

Background Lenke 5 C curves are frequently associated with clinically and radiological coronal imbalance. Appropriate selection of proximal and distal levels of fusion is essential to ensure good coronal balance (CB). We aimed to evaluate radiological factors associated with (I) global CB in the early post-operative period; (II) late decompensation of CB; and (III) favourable spontaneous correction of CB on long term follow up. Methods Twenty-three Lenke type 5C scoliosis cases treated with selective posterior lumbar instrumentation were retrospectively evaluated. Pre-operative, early post-operative and late post-operative (>2 years) whole length radiographs were analysed. Cobb’s angle, lumbar lordosis, coronal imbalance, lower instrumented vertebra (LIV) tilt and translation and upper instrumented vertebra (UIV) tilt and translation were measured. The proximal and distal fusion levels were noted and correlated with post-operative CB. Results There were 21 females and 2 males with a mean follow up of 36 months. The mean pre-operative cobb angle was 55°±13.26°, which corrected to 14.7°±8.84° and was maintained on follow up. Eight patients had early post-operative coronal imbalance with spontaneous resolution seen in six cases on long term follow-up. At final follow-up, four cases had coronal imbalance (persistent imbalance since early post-operative period =2; late decompensation =2). In cases with early imbalance 5/8 cases had a pre-operative LIV tilt of ≥25°. All four patients with coronal imbalance at final follow-up had pre-operative LIV tilt ≥25°. Radiographic parameters which correlated with post-operative coronal imbalance were pre-operative LIV tilt (r=0.64, P=0.001), pre-operative LIV translation (r=0.696, P<0.001), pre-operative UIV translation (r=0.44, P=0.030), post-operative LIV tilt (r=0.804, P<0.001), and post-operative UIV tilt (r=0.62, P=0.001). Conclusions In Lenke 5C scoliosis, a pre-operative LIV tilt ≥25° significantly correlates with post-operative global coronal imbalance. Increasing UIV tilt may be a factor that accounts for improvement of CB in late follow-up period. PMID:29354729

Evidence of suppressed heating of coronal loops rooted in opposite polarity sunspot umbrae

NASA Astrophysics Data System (ADS)

Tiwari, Sanjiv K.; Thalmann, Julia K.; Winebarger, Amy R.; Panesar, Navdeep K.; Moore, Ronald

2015-04-01

Observations of active region (AR) coronae in different EUV wavelengths reveal the presence of various loops at different temperatures. To understand the mechanisms that result in hotter or cooler loops, we study a typical bipolar AR, near solar disk center, which has moderate overall magnetic twist and at least one fully developed sunspot of each polarity. From AIA 193 and 94 A images we identify many clearly discernible coronal loops that connect opposite-polarity plage or a sunspot to a opposite-polarity plage region. The AIA 94 A images show dim regions in the umbrae of the spots. To see which coronal loops are rooted in a dim umbral area, we performed a non-linear force-free field (NLFFF) modeling using photospheric vector magnetic field measurements obtained with the Heliosesmic Magnetic Imager (HMI) onboard SDO. After validation of the NLFFF model by comparison of calculated model field lines and observed loops in AIA 193 and 94 A, we specify the photospheric roots of the model field lines. The model field then shows the coronal magnetic loops that arch from the dim umbral area of the positive-polarity sunspot to the dim umbral area of a negative-polarity sunspot. Because these coronal loops are not visible in any of the coronal EUV and X-ray images of the AR, we conclude they are the coolest loops in the AR. This result suggests that the loops connecting opposite polarity umbrae are the least heated because the field in umbrae is so strong that the convective braiding of the field is strongly suppressed.From this result, we further hypothesize that the convective freedom at the feet of a coronal loop, together with the strength of the field in the body of the loop, determines the strength of the heating. In particular, we expect the hottest coronal loops to have one foot in an umbra and the other foot in opposite-polarity penumbra or plage (coronal moss), the areas of strong field in which convection is not as strongly suppressed as in umbrae. Many transient, outstandingly bright, loops in the AIA 94 A movie of the AR do have this expected rooting pattern.

Automated detection of open magnetic field regions in EUV images

NASA Astrophysics Data System (ADS)

Krista, Larisza Diana; Reinard, Alysha

2016-05-01

Open magnetic regions on the Sun are either long-lived (coronal holes) or transient (dimmings) in nature, but both appear as dark regions in EUV images. For this reason their detection can be done in a similar way. As coronal holes are often large and long-lived in comparison to dimmings, their detection is more straightforward. The Coronal Hole Automated Recognition and Monitoring (CHARM) algorithm detects coronal holes using EUV images and a magnetogram. The EUV images are used to identify dark regions, and the magnetogam allows us to determine if the dark region is unipolar - a characteristic of coronal holes. There is no temporal sensitivity in this process, since coronal hole lifetimes span days to months. Dimming regions, however, emerge and disappear within hours. Hence, the time and location of a dimming emergence need to be known to successfully identify them and distinguish them from regular coronal holes. Currently, the Coronal Dimming Tracker (CoDiT) algorithm is semi-automated - it requires the dimming emergence time and location as an input. With those inputs we can identify the dimming and track it through its lifetime. CoDIT has also been developed to allow the tracking of dimmings that split or merge - a typical feature of dimmings.The advantage of these particular algorithms is their ability to adapt to detecting different types of open field regions. For coronal hole detection, each full-disk solar image is processed individually to determine a threshold for the image, hence, we are not limited to a single pre-determined threshold. For dimming regions we also allow individual thresholds for each dimming, as they can differ substantially. This flexibility is necessary for a subjective analysis of the studied regions. These algorithms were developed with the goal to allow us better understand the processes that give rise to eruptive and non-eruptive open field regions. We aim to study how these regions evolve over time and what environmental factors influence their growth and decay over short and long time-periods (days to solar cycles).

Large-Scale Coronal Heating from "Cool" Activity in the Solar Magnetic Network

NASA Technical Reports Server (NTRS)

Falconer, D. A.; Moore, R. L.; Porter, J. G.; Hathaway, D. H.

1999-01-01

In Fe XII images from SOHO/EIT, the quiet solar corona shows structure on scales ranging from sub-supergranular (i.e., bright points and coronal network) to multi-supergranular (large-scale corona). In Falconer et al 1998 (Ap.J., 501, 386) we suppressed the large-scale background and found that the network-scale features are predominantly rooted in the magnetic network lanes at the boundaries of the supergranules. Taken together, the coronal network emission and bright point emission are only about 5% of the entire quiet solar coronal Fe XII emission. Here we investigate the relationship between the large-scale corona and the network as seen in three different EIT filters (He II, Fe IX-X, and Fe XII). Using the median-brightness contour, we divide the large-scale Fe XII corona into dim and bright halves, and find that the bright-half/dim half brightness ratio is about 1.5. We also find that the bright half relative to the dim half has 10 times greater total bright point Fe XII emission, 3 times greater Fe XII network emission, 2 times greater Fe IX-X network emission, 1.3 times greater He II network emission, and has 1.5 times more magnetic flux. Also, the cooler network (He II) radiates an order of magnitude more energy than the hotter coronal network (Fe IX-X, and Fe XII). From these results we infer that: 1) The heating of the network and the heating of the large-scale corona each increase roughly linearly with the underlying magnetic flux. 2) The production of network coronal bright points and heating of the coronal network each increase nonlinearly with the magnetic flux. 3) The heating of the large-scale corona is driven by widespread cooler network activity rather than by the exceptional network activity that produces the network coronal bright points and the coronal network. 4) The large-scale corona is heated by a nonthermal process since the driver of its heating is cooler than it is. This work was funded by the Solar Physics Branch of NASA's office of Space Science through the SR&T Program and the SEC Guest Investigator Program.

Incidence of skin diseases diagnosed in a public institution: comparison between 2003 and 2014.

PubMed

Miguel, Livia Maria Zanardi; Jorge, Marilia Formentini Scotton; Rocha, Bruna; Miot, Hélio Amante

2017-01-01

Epidemiology of diseases is influenced by population socio-demographic circumstances. Therefore it can be modified along the time. There are no studies exploring epidemiological transition in dermatology. This study investigated the incidence of dermatoses in new patients from a Brazilian country town public service in 2003 and 2014. There was a significant increase in the incidence of sexually transmitted diseases, leprosy, melasma, pruritus and hidradenitis suppurativa. However, a prominent reduction in scheduling of appointments for surgeries of benign lesions, drug reactions, urticaria and superficial mycoses was detected. The identification of epidemiological trends guides the dimensioning of health system and professional qualification policies.

Solar and stellar coronal plasmas

NASA Technical Reports Server (NTRS)

Golub, Leon

1989-01-01

Progress in observational, theoretical, and radio studies of coronal plasmas is summarized. Specifically work completed in the area of solar and stellar magnetic fields, related photospheric phenomena and the relationships between magnetism, rotation, coronal and chromospheric emission in solar-like stars is described. Also outlined are theoretical studies carried out in the following areas, among others: (1) neutral beams as the dominant energy transport mechanism in two ribbon-flares; (2) magneto hydrodynamic and circuit models for filament eruptions; and (3) studies of radio emission mechanisms in transient events. Finally, radio observations designed for coronal activity studies of the sun and of solar-type coronae are described. A bibliography of publications and talks is provided along with reprints of selected articles.

Non-inductive current driven by Alfvén waves in solar coronal loops

NASA Astrophysics Data System (ADS)

Elfimov, A. G.; de Azevedo, C. A.; de Assis, A. S.

1996-08-01

It has been shown that Alfvén waves can drive non-inductive current in solar coronal loops via collisional or collisionless damping. Assuming that all the coronal-loop density of dissipated wave power (W= 10-3 erg cm-3 s-1), which is necessary to keep the plasma hot, is due to Alfvén wave electron heating, we have estimated the axial current density driven by Alfvén waves to be ≈ 103 105 statA cm-2. This current can indeed support the quasi-stationary equilibrium and stability of coronal loops and create the poloidal magnetic field up to B θ≈1-5 G.

The Fundamental Structure of Coronal Loops

NASA Technical Reports Server (NTRS)

Winebarger, Amy; Warren, Harry; Cirtain, Jonathan; Kobayashi, Ken; Korreck, Kelly; Golub, Leon; Kuzin, Sergey; Walsh, Robert; DePontieu, Bart; Title, Alan;

A Multiwavelength Study of Coronal Structure: A Simultaneous Observation from NIXT and YOHKOH

NASA Technical Reports Server (NTRS)

Golub, Leon

1998-01-01

Solar soft X-ray images taken simultaneously by the Yohkoh and the Normal Incidence X-ray Telescope (NIXT) reveal significantly different coronal structures. Coronal loops are more clearly seen in the Yohkoh images, and the isolated island-like structures seen in the NIXT image have been found to correspond to the footpoints of the Yohkoh loops. The difference is due to the difference in the temperature response of the telescopes: NIXT is sensitive to temperatures ranging from 0.9 to 3 MK, while Yohkoh is more sensitive to temperatures above 2.5 MK. The morphological differences reflect the multi-temperature (1-5 MK) nature of the solar coronal plasmas.

Geographical Areas and Plant Facilities for Educational Purposes in Vermont.

ERIC Educational Resources Information Center

Dunham, Paul C.

School districts in Vermont are organized generally along town boundary lines with no clear distinction between town and school governmental units. State financial distributions are usually made to the town, and taxes are billed and collected by the town. There is a need for school district reorganization in terms of larger unified or 12-grade…

Socioeconomic Indicators for Small Towns. Small Town Strategy.

ERIC Educational Resources Information Center

Oregon State Univ., Corvallis. Cooperative Extension Service.

Prepared to help small towns assess community population and economic trends, this publication provides a step-by-step guide for establishing an on-going local data collection system, which is based on four local indicators and will provide accurate, up-to-date estimates of population, family income, and gross sales within a town's trade area. The…

Changes in Small Town Social Capital and Civic Engagement

ERIC Educational Resources Information Center

Besser, Terry L.

2009-01-01

Small towns are often depicted as places with many interpersonal relationships and generalized trust, or high social capital. Social capital is a resource which towns can use to solve problems and improve the local quality of life. In this paper, I determined if social capital and civic engagements have declined in small towns in the U.S. Midwest…

An Experimental Investigation of News Source and the Hostile Media Effect.

ERIC Educational Resources Information Center

Arpan, Laura M.; Raney, Arthur A.

2003-01-01

Examines the interaction among different news sources, individual levels of partisanship, and the hostile media effect in sports news. Explains that university students read a balanced story about their home-town college football team in one of three newspapers: the home-town, the cross-state rival university's town, or a neutral town paper.…

Microleakage of adhesive restorative materials.

PubMed

Gladys, S; Van Meerbeek, B; Lambrechts, P; Vanherle, G

2001-06-01

To compare the marginal sealing ability of two conventional and one polyacid-modified resin-based composite, and two conventional and three resin-modified glass-ionomers in conventional cylindrical box cavities following a silver-staining microleakage evaluation method. In 80 freshly extracted and caries-free human third molars, three standardized cylindrical butt-joint cavities were prepared: the first cavity in coronal enamel, the second at the cemento-enamel junction (CEJ) and the third completely in root cementum. A control group of 10 additional teeth was chosen. After the cavities were restored randomly using the eight restorative materials tested, the specimens were first stored in distilled water at 37 degrees C for 7 days and then thermocycled (500 cycles). Thereafter, the specimens were centrifuged for 10 min in plastic bottles containing 50 wt% silver nitrate aqueous solution. The degree of microleakage was recorded at four different depths along the restoration margins using an optical stereomicroscope equipped with a measuring gauge. None of the tested systems prevented microleakage completely, but the extent of leakage decreased towards the bottom of the restorations. The resin-modified glass-ionomers performed better than the conventional resin-based composites and conventional glass-ionomers. Distinct leakage patterns were recorded among all materials investigated. Complete marginal sealing could still not be reached with the new adhesive restorative materials.

Iron charge states observed in the solar wind

NASA Technical Reports Server (NTRS)

Ipavich, F. M.; Galvin, A. B.; Gloeckler, G.; Hovestadt, D.; Klecker, B.; Scholer, M.

1983-01-01

Solar wind measurements from the ULECA sensor of the Max-Planck-Institut/University of Maryland experiment on ISEE-3 are reported. The low energy section of approx the ULECA sensor selects particles by their energy per charge (over the range 3.6 keV/Q to 30 keV/Q) and simultaneously measures their total energy with two low-noise solid state detectors. Solar wind Fe charge state measurements from three time periods of high speed solar wind occurring during a post-shock flow and a coronal hole-associated high speed stream are presented. Analysis of the post-shock flow solar wind indicates the charge state distributions for Fe were peaked at approx +16, indicative of an unusually high coronal temperature (3,000,000 K). In contrast, the Fe charge state distribution observed in a coronal hole-associated high speed stream peaks at approx -9, indicating a much lower coronal temperature (1,400,000 K). This constitutes the first reported measurements of iron charge states in a coronal hole-associated high speed stream.

[The coroner's autopsies in the Great Britain: the problems related to the quality of the studies, standardization, auditing, financial support and the approaches to their solution].

PubMed

Makarov, I Yu; Fetisov, V A; Filimonov, B A; Gusarov, A A

The objective of the present study was to analyze the experience of the coroners and pathologists in the Great Britain based on the results of the coroner's autopsies and recommendations of the experts involved in the activities carried out in the framework of the National Confidential Enquiry into Patient Outcome and Death program (NCEPOD). The recommendations are designed to reform the country's medical examiner system, improve the equipment of the mortuary facilities, and optimize funding for the autopsy studies. The authors consider in the chronological order the following issues of the coroners and pathologists' activities: organization of their work and its procedural aspects, ordering coroner's autopsies, preparation for their performance, analysis of the relevant documentation (autopsy reports) and medical case histories (discharge summaries). Also discussed are the recommendations of the NCEPOD experts for the improvement of the said studies with the detailed analysis of the causes underlying the aforementioned problems and concise comments of the authors.

Interaction of minor ions with fast and slow shocks

NASA Technical Reports Server (NTRS)

Whang, Y. C.

1990-01-01

The coronal slow shock was predicted to exist embedded in large coronal holes at 4 to 10 solar radii. A three-fluid model was used to study the jumps in minor ions propertes across the coronal slow shock. The jump conditions were formulated in the de Hoffmann-Teller frame of reference. The Rankine-Hugoniot solution determines the MHD flow and the magnetic field across the shocks. For each minor ion species, the fluid equations for the conservation of mass, momentum, and energy can be solved to determine the velocity and the temperature of the ions across the shock. A simularity solution was also obtained for heavy ions. The results show that on the downstream side of the coronal slow shock the ion temperatures are nearly proportional to the ion masses for He, O, Si, and Fe in agreement with observed ion temperatures in the inner solar wind. This indicates that the possibly existing coronal slow shock can be responsible for the observed heating of minor ions in the solar wind.

Solar-burst precursors and energy buildup at microwave wavelengths

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lang, K.R.; Willson, R.F.

High-resolution microwave observations (VLA) of heating and magnetic triggering in coronal loops are summarized. Magnetic changes that precede solar eruptions on time scales of tens of minutes involve primarily emerging coronal loops and the interaction of two or more loops. Thermal cyclotron lines were detected in coronal loops, suggesting the presence of hot current sheets that enhance emission from relatively thin layers of enhanced temperature and constant magnetic field. These current sheets may play a role in the excitation of solar bursts. A filament-associated source with a high brightness temperature and steep radiation spectrum occurs above a region of apparentlymore » weak photospheric field. This source might be attributed to currents that enhance coronal magnetic fields. Compact (phi=5 sec) transient sources with lifetimes of 30 to 60 minutes were also detected in regions of apparently weak photospheric field. VLA observations of coronal loops are compared with simultaneous SMM-XRP observations in conclusion.« less

Magnetic Topology of a Long-Lived Coronal Condensation Site Lasting Eight Months

NASA Astrophysics Data System (ADS)

Sun, X.; Yu, S.; Liu, W.

2017-12-01

It is well known that cool material, such as prominences or coronal rain, can form in-situ by condensation of hot coronal plasma due to a runaway radiative cooling instability (a.k.a. thermal non-equilibrium). Recent observations and numerical simulations suggest that such condensations are quite common, but in quiet-Sun regions, they occur preferentially in locations where magnetic field is weak (e.g., null points) or discontinuous (e.g., current sheets). Such events usually have short lifetimes of hours to days. Surprisingly, we observed a high-latitude condensation site lasting over eight months in 2014 with recurrent and episodic condensations fueling a funnel-shaped prominence. We analyze the coronal magnetic topology to investigate the necessary condition of such a long-lived condensation site. We find that the site was directly above a poleward photospheric flux surge when the polar field polarity was close to its solar cycle reversal. The large-scale magnetic cancellation front may have sustained interchange reconnection at this location, creating suitable conditions for coronal plasma condensation.

Sources of magnetic fields in recurrent interplanetary streams

NASA Technical Reports Server (NTRS)

Burlaga, L. F.; Behannon, K. W.; Hansen, S. F.; Pneuman, G. W.; Feldman, W. C.

1977-01-01

The sources of magnetic fields in recurrent streams were examined. Most fields and plasmas at 1 AU were related to coronal holes, and the magnetic field lines were open in those holes. Some of the magnetic fields and plasmas were related to open field line regions on the sun which were not associated with known coronal holes, indicating that open field lines are more basic than coronal holes as sources of the solar wind. Magnetic field intensities in five equatorial coronal holes ranged from 2G to 18G. Average measured photospheric magnetic fields along the footprints of the corresponding unipolar fields on circular equatorial arcs at 2.5 solar radii had a similar range and average, but in two cases the intensities were approximately three times higher than the projected intensities. The coronal footprints of the sector boundaries on the source surface at 2.5 solar radii, meandered between -45 deg and +45 deg latitude, and their inclination ranged from near zero to near ninety degrees.

First Record of Culex coronator In Shelby County, Tennessee.

PubMed

Trimm, Amy; Insch, Andrew; Carlson, Ture

2017-12-01

Culex coronator has been identified in Shelby County, TN, for the first time as an established species. This is an important discovery since the range of Cx. coronator is unknown in Tennessee and it has been found positive for West Nile virus. Larvae and an adult were discovered during routine surveillance. Larvae were collected at 9 different locations, while the 1 adult captured was at the 10th isolated location.

Coronal View Ultrasound Imaging of Movement in Different Segments of the Tongue during Paced Recital: Findings from Four Normal Speakers and a Speaker with Partial Glossectomy

ERIC Educational Resources Information Center

Bressmann, Tim; Flowers, Heather; Wong, Willy; Irish, Jonathan C.

2010-01-01

The goal of this study was to quantitatively describe aspects of coronal tongue movement in different anatomical regions of the tongue. Four normal speakers and a speaker with partial glossectomy read four repetitions of a metronome-paced poem. Their tongue movement was recorded in four coronal planes using two-dimensional B-mode ultrasound…

Application of a magnetograph and X-ray telescope to the study of coronal structure variations

NASA Technical Reports Server (NTRS)

Rust, D. M.

1980-01-01

The application of magnetographs and X-ray imaging techniques to determine the magnitude, structure, origin, and evolution of the solar coronal magnetic field is examined. The spatial and temporal resolution of the X-ray telescope is discussed and a comparison of ground based magnetogram sequences versus a magnetograph in space is presented. Skylab photographs of the evolution of transient coronal holes are provided.

Cosmic Ray Measurements Inside Mir With Sileye-2

NASA Astrophysics Data System (ADS)

Casolino, M.; Sileye-2 Team

smallIntensity of the coronal green line (small = 5303cm) is considered as an impor- tant parameter to characterize the changes of diffusion coefficient of galactic cosmic rays versus the solar activity. A contribution of the coronal green line intensity in GCR diffusion coefficient is taken into account using its real distribution on the whole disk of the Sun averaging for three days. An assumption is made that the observed changes of the intensity of the coronal green line on the Sun's surface is taken away to the in- terplanetary space with the average solar wind velocity, U = 400 km/s. Thus, to cover the modulation region of the size of the 100 AU there is necessary data of the coronal green line intensity of the one-year duration. Alternating the coefficient of proportion- ality between the intensity of coronal green line and the diffusion coefficient of GCR the appropriate correspondence between the observation of GCR intensity sensitive to neutron monitors and solution of the Parker's transport equation have been found. The best correspondence between the observation of GCR intensity and solution of the Parker's transport equation has been found when the role of the coronal green line intensity in diffusion coefficient of GCR is gradually diminished versus the distance from the Sun.

“Dandelion” Filament Eruption and Coronal Waves Associated with a Solar Flare on 2011 February 16

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cabezas, Denis P.; Ishitsuka, Mutsumi; Ishitsuka, José K.

Coronal disturbances associated with solar flares, such as H α Moreton waves, X-ray waves, and extreme ultraviolet (EUV) coronal waves, are discussed herein in relation to magnetohydrodynamic fast-mode waves or shocks in the corona. To understand the mechanism of coronal disturbances, full-disk solar observations with high spatial and temporal resolution over multiple wavelengths are of crucial importance. We observed a filament eruption, whose shape is like a “dandelion,” associated with the M1.6 flare that occurred on 2011 February 16 in H α images taken by the Flare Monitoring Telescope at Ica University, Peru. We derive the three-dimensional velocity field ofmore » the erupting filament. We also identify winking filaments that are located far from the flare site in the H α images, whereas no Moreton wave is observed. By comparing the temporal evolution of the winking filaments with those of the coronal wave seen in the EUV images data taken by the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory and by the Extreme Ultraviolet Imager on board the Solar Terrestrial Relations Observatory-Ahead , we confirm that the winking filaments were activated by the EUV coronal wave.« less

Generating sustainable towns from Chinese villages: a system modeling approach.

PubMed

Levine, Richard S; Hughes, Michael T; Ryan Mather, Casey; Yanarella, Ernest J

2008-04-01

The great majority of China's developing towns will be extensions of already existing villages. With the prospect of hundreds of millions of Chinese farmers projected to leave their villages to become industrial workers in new and expanded towns within the next few years, new challenges will be faced. As expansion and modernization progress, this development moves from the traditional village model that operates not far from resource sustainability to increasingly unsustainable patterns of commerce, urban development, and modern life. With such an unprecedented mass migration and transformation, how can Chinese culture survive? What is to become of the existing million plus agricultural villages? How can these massively unsustainable new industrial towns survive? In the European Commission sponsored research program SUCCESS, researchers worked from the scale of the Chinese village to find viable answers to these questions. To address these issues, the Center for Sustainable Cities, one of the SUCCESS teams, studied the metabolism of several small villages. In these studies, system dynamics models of a village's metabolism were created and then modified so that inherently unsustainable means were eliminated from the model (fossil fuels, harmful agricultural chemicals, etc.) and replaced by sustainability-oriented means. Small Chinese farming villages are unlikely to survive in anything like their present form or scale, not least because they are too small to provide the range of life opportunities to which the young generation of educated Chinese aspires. As a response to this realization as well as to the many other threats to the Chinese village and its rural way of life, it was proposed that one viable path into the future would be to enlarge the villages to become full service towns with sufficient diversity of opportunity to be able to attract and keep many of the best and brightest young people who are now migrating to the larger cities. Starting with the village in its sustainability-oriented model form, the village model would be enlarged both quantitatively and qualitatively through many trial iterations. A research program is described whereby an operational definition of the sustainable city is developed as a means of creating these enlarged models through citizen participation assisted by outside experts using software under development called the Sustainability Engine to guide the process and provide feedback as to the consequences of various proposals that are brought to the table. As this process is continued, the village would be incrementally enlarged and made more diverse and more complex through a variety of scenarios until it would emerge as a modern, sustainable town or city. In this way, through a participatory, balance-seeking civil society process involving villagers and scientists in what the Center for Sustainable Cities calls the Sustainable City Game, the villages can become the DNA for generating future sustainable Chinese towns and cities. As an extension of this discussion, a new urban model, the Sustainable City-as-a-Hill, is presented that responds to both the qualities of the traditional Chinese village as well as to the modern demands of industrial and post-industrial economies and, in particular, to the need for sustainable urban patterns. In addition a new concept, the Sustainable Area Budget (SAB) is introduced which definitively creates the boundary condition for both modeling the sustainable city and presenting the quest for the sustainable city-region as a coherent, scientific design process.

Relationship of EUV Irradiance Coronal Dimming Slope and Depth to Coronal Mass Ejection Speed and Mass

NASA Technical Reports Server (NTRS)

Mason, James Paul; Woods, Thomas N.; Webb, David F.; Thompson, Barbara J.; Colaninno, Robin C.; Vourlidas, Angelos

2016-01-01

Extreme ultraviolet (EUV) coronal dimmings are often observed in response to solar eruptive events. These phenomena can be generated via several different physical processes. For space weather, the most important of these is the temporary void left behind by a coronal mass ejection (CME). Massive, fast CMEs tend to leave behind a darker void that also usually corresponds to minimum irradiance for the cooler coronal emissions. If the dimming is associated with a solar are, as is often the case, the are component of the irradiance light curve in the cooler coronal emission can be isolated and removed using simultaneous measurements of warmer coronal lines. We apply this technique to 37dimming events identified during two separate two-week periods in 2011, plus an event on 2010 August 7 analyzed in a previous paper, to parameterize dimming in terms of depth and slope. We provide statistics on which combination of wavelengths worked best for the flare-removal method, describe the fitting methods applied to the dimming light curves, and compare the dimming parameters with corresponding CME parameters of mass and speed. The best linear relationships found are nu(sub CME) [km/s] approx. equals 2.36 x 10 6 [km/%] x s(sub dim) [%/s] m(sub CME) [g] approx. equals 2.59 x 10(exp.15 [g/%] x the square root of d(sub dim) [%].These relationships could be used for space weather operations of estimating CME mass and speed using near-real-time irradiance dimming measurements.

MULTI-STRAND CORONAL LOOP MODEL AND FILTER-RATIO ANALYSIS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bourouaine, Sofiane; Marsch, Eckart, E-mail: bourouaine@mps.mpg.d

2010-01-10

We model a coronal loop as a bundle of seven separate strands or filaments. Each of the loop strands used in this model can independently be heated (near their left footpoints) by Alfven/ion-cyclotron waves via wave-particle interactions. The Alfven waves are assumed to penetrate the strands from their footpoints, at which we consider different wave energy inputs. As a result, the loop strands can have different heating profiles, and the differential heating can lead to a varying cross-field temperature in the total coronal loop. The simulation of Transition Region and Coronal Explorer (TRACE) observations by means of this loop modelmore » implies two uniform temperatures along the loop length, one inferred from the 171:195 filter ratio and the other from the 171:284 ratio. The reproduced flat temperature profiles are consistent with those inferred from the observed extreme-ultraviolet coronal loops. According to our model, the flat temperature profile is a consequence of the coronal loop consisting of filaments, which have different temperatures but almost similar emission measures in the cross-field direction. Furthermore, when we assume certain errors in the simulated loop emissions (e.g., due to photometric uncertainties in the TRACE filters) and use the triple-filter analysis, our simulated loop conditions become consistent with those of an isothermal plasma. This implies that the use of TRACE or EUV Imaging Telescope triple filters for observation of a warm coronal loop may not help in determining whether the cross-field isothermal assumption is satisfied or not.« less

Coronal Mass Ejections and Dimmings: A Comparative Study using MHD Simulations and SDO Observations

NASA Astrophysics Data System (ADS)

Jin, M.; Cheung, C. M. M.; DeRosa, M. L.; Nitta, N.; Schrijver, K.

2017-12-01

Solar coronal dimmings have been observed extensively in the past two decades. Due to their close association with coronal mass ejections (CMEs), there is a critical need to improve our understanding of the physical processes that cause dimmings and determine their relationship with CMEs. In this study, we investigate coronal dimmings by combining simulation and observational efforts. By utilizing a data-driven global magnetohydrodynamics model (AWSoM: Alfven-wave Solar Model), we simulate coronal dimmings resulting from different CME energetics and flux rope configurations. We synthesize the emissions of different EUV spectral bands/lines and compare with SDO/AIA and EVE observations. A detailed analysis of simulation and observation data suggests that although the transient dimming / brightening patterns could relate to plasma heating processes (either by adiabatic compression or reconnection), the long-lasting "core" and "remote" (also known as "secondary") dimmings both originate from regions with open/quasi-open fields and are caused by mass loss process. The mass loss in the remote dimming region is induced by CME-driven shock. Using metrics such as dimming depth, dimming slope, and recovery time, we investigate the relationship between dimmings and CME properties (e.g., CME mass, CME speed) in the simulation. Our result suggests that coronal dimmings encode important information about CME energetics, CME-driven shock properties, and magnetic configuration of erupting flux ropes. We also discuss how our knowledge about solar coronal dimmings could be extended to the study of stellar CMEs, which may prove important for exoplanet atmospheres and habitability but which are currently not observable.

Space Oddities: The Search For Ephemeral Coronal Holes

NASA Astrophysics Data System (ADS)

O'Connor, Rachel E.; Pesnell, W. Dean; Kirk, Michael S.; Karna, Nishu

2016-10-01

Ephemeral coronal holes are short-lived, volatile counterparts to equatorial coronal holes. Very little is known about their characteristics and behavior aside from their definition: open, unipolar magnetic field lines resulting in darkened regions of the corona. The first exemplar of this phenomenon was observed by NASA's Solar Dynamics Observatory (SDO) on October 26, 2010, which spurred our search for other occurrences in order to understand the frequency and evolution of these phenomena. To accomplish this, we visually evaluated SDO 211 Å images on a 12-hour cadence between June 2010 and June 2016. Each compact and isolated dim region we encountered was flagged as a potential ephemeral coronal hole for further analysis. This preliminary effort resulted in 149 candidate holes. For further analysis of their characteristics, we applied a strict definition criterion of an ephemeral coronal hole. This criterion was a set of four factors that were created in order to ensure events being observed were isolated, individual events- the candidates had to be dark relative to the surrounding material, not influenced by a nearby eruption, not obviously connected to other coronal hole structures, and their lifetime had to occur completely within the disk crossing. This criterion was designed so that events could be completely analyzed, from beginning to end, to better understand the origins. Application of this criterion eliminated all candidates but 5 of the original 149. True ephemeral coronal holes are rare occurrences, appearing only five times in six years. Future research in this area is needed to both locate additional events and study the underlying driving forces behind these rare phenomena.

RECONNECTION-DRIVEN CORONAL-HOLE JETS WITH GRAVITY AND SOLAR WIND

DOE Office of Scientific and Technical Information (OSTI.GOV)

Karpen, J. T.; DeVore, C. R.; Antiochos, S. K.

Coronal-hole jets occur ubiquitously in the Sun's coronal holes, at EUV and X-ray bright points associated with intrusions of minority magnetic polarity. The embedded-bipole model for these jets posits that they are driven by explosive, fast reconnection between the stressed closed field of the embedded bipole and the open field of the surrounding coronal hole. Previous numerical studies in Cartesian geometry, assuming uniform ambient magnetic field and plasma while neglecting gravity and solar wind, demonstrated that the model is robust and can produce jet-like events in simple configurations. We have extended these investigations by including spherical geometry, gravity, and solarmore » wind in a nonuniform, coronal hole-like ambient atmosphere. Our simulations confirm that the jet is initiated by the onset of a kink-like instability of the internal closed field, which induces a burst of reconnection between the closed and external open field, launching a helical jet. Our new results demonstrate that the jet propagation is sustained through the outer corona, in the form of a traveling nonlinear Alfvén wave front trailed by slower-moving plasma density enhancements that are compressed and accelerated by the wave. This finding agrees well with observations of white-light coronal-hole jets, and can explain microstreams and torsional Alfvén waves detected in situ in the solar wind. We also use our numerical results to deduce scaling relationships between properties of the coronal source region and the characteristics of the resulting jet, which can be tested against observations.« less

The Influence of the Solar Coronal Radiation on Coronal Plasma Structures, I: Determination of the Incident Coronal Radiation

NASA Astrophysics Data System (ADS)

Brown, Gerrard M.; Labrosse, Nicolas

2018-02-01

Coronal structures receive radiation not only from the solar disc, but also from the corona. This height-dependent incident radiation plays a crucial role in the excitation and the ionisation of the illuminated plasma. The aim of this article is to present a method for computing the detailed incident radiation coming from the solar corona, which is perceived at a point located at an arbitrary height. The coronal radiation is calculated by integrating the radiation received at a point in the corona over all of the corona visible from this point. The emission from the corona at all wavelengths of interest is computed using atomic data provided by CHIANTI. We obtain the spectrum illuminating points located at varying heights in the corona at wavelengths between 100 and 912 Å when photons can ionise H or He atoms and ions in their ground states. As expected, individual spectral lines will contribute most at the height within the corona where the local temperature is closest to their formation temperature. As there are many spectral lines produced by many ions, the coronal intensity cannot be assumed to vary in the same way at all wavelengths and so must be calculated for each separate height that is to be considered. This code can be used to compute the spectrum from the corona illuminating a point at any given height above the solar surface. This brings a necessary improvement to models where an accurate determination of the excitation and ionisation states of coronal plasma structures is crucial.

Two Coronal Holes on the Sun Viewed by SDO

NASA Image and Video Library

2015-03-17

NASA’s Solar Dynamics Observatory, or SDO, captured this solar image on March 16, 2015, which clearly shows two dark patches, known as coronal holes. The larger coronal hole of the two, near the southern pole, covers an estimated 6- to 8-percent of the total solar surface. While that may not sound significant, it is one of the largest polar holes scientists have observed in decades. The smaller coronal hole, towards the opposite pole, is long and narrow. It covers about 3.8 billion square miles on the sun - only about 0.16-percent of the solar surface. Coronal holes are lower density and temperature regions of the sun’s outer atmosphere, known as the corona. Coronal holes can be a source of fast solar wind of solar particles that envelop the Earth. The magnetic field in these regions extends far out into space rather than quickly looping back into the sun’s surface. Magnetic fields that loop up and back down to the surface can be seen as arcs in non-coronal hole regions of the image, including over the lower right horizon. The bright active region on the lower right quadrant is the same region that produced solar flares last week. Credit: NASA/Goddard/SDO NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

Coronal imbalance in degenerative lumbar scoliosis: Prevalence and influence on surgical decision-making for spinal osteotomy.

PubMed

Bao, H; Yan, P; Qiu, Y; Liu, Z; Zhu, F

2016-09-01

There is a paucity of information on the pre-operative coronal imbalance in patients with degenerative lumbar scoliosis (DLS) and its influence on surgical outcomes. A total of 284 DLS patients were recruited into this study, among whom 69 patients were treated surgically and the remaining 215 patients conservatively Patients were classified based on the coronal balance distance (CBD): Type A, CBD < 3 cm; Type B, CBD > 3 cm and C7 Plumb Line (C7PL) shifted to the concave side of the curve; Type C, CBD > 3 cm and C7PL shifted to the convex side. A total of 99 of the 284 (34.8%) patient presented with a pre-operative coronal imbalance (mean CBD: 48.5, standard deviation 18.7 mm). More patients with a Type B malalignment were observed than with a Type C malalignment (62 versus 37). A total of 21 pf the 69 (30.4%) surgically treated patients had a post-operative coronal imbalance, which was found to be more prevalent in Type C patients (p < 0.001). At follow-up, less improvement was observed in terms of Short Form-36 Physical Component Score and visual analogue score for back pain (p = 0.034 and 0.025, respectively) in Type C patients. This study shows that patients with Type C coronal malalignment may be at greater risk of post-operative coronal imbalance following posterior osteotomy. Cite this article: Bone Joint J 2016;98-B:1227-33. ©2016 The British Editorial Society of Bone & Joint Surgery.

Can coronal hole spicules reach coronal temperatures?

NASA Astrophysics Data System (ADS)

Madjarska, M. S.; Vanninathan, K.; Doyle, J. G.

2011-08-01

Aims: The present study aims to provide observational evidence of whether coronal hole spicules reach coronal temperatures. Methods: We combine multi-instrument co-observations obtained with the SUMER/SoHO and with the EIS/SOT/XRT/Hinode. Results: The analysed three large spicules were found to be comprised of numerous thin spicules that rise, rotate, and descend simultaneously forming a bush-like feature. Their rotation resembles the untwisting of a large flux rope. They show velocities ranging from 50 to 250 kms-1. We clearly associated the red- and blue-shifted emissions in transition region lines not only with rotating but also with rising and descending plasmas. Our main result is that these spicules although very large and dynamic, are not present in the spectral lines formed at temperatures above 300 000 K. Conclusions: In this paper we present the analysis of three Ca ii H large spicules that are composed of numerous dynamic thin spicules but appear as macrospicules in lower resolution EUV images. We found no coronal counterpart of these and smaller spicules. We believe that the identification of phenomena that have very different origins as macrospicules is due to the interpretation of the transition region emission, and especially the He ii emission, wherein both chromospheric large spicules and coronal X-ray jets are present. We suggest that the recent observation of spicules in the coronal AIA/SDO 171 Å and 211 Å channels probably comes from the existence of transition region emission there. Movie is available in electronic form at http://www.aanda.org

On Heating Large Bright Coronal Loops by Magnetic Microexplosions at their Feet

NASA Technical Reports Server (NTRS)

Moore, Ronald L; Falconer, D. A.; Porter, Jason G.

1999-01-01

In previous work, by registering Yohkoh SXT coronal X-ray images with MSFC vector magnetograms, we found that: (1) many of the larger bright coronal loops rooted at one or both ends in an active region are rooted around magnetic islands of included polarity, (2) the core field encasing the neutral line encircling the island is strongly sheared, and (3) this sheared core field is the seat of frequent microflares. This suggests that the coronal heating in these extended bright loops is driven by many small explosive releases of stored magnetic energy from the sheared core field at their feet, some of which magnetic microexplosions also produce the microflare heating in the core fields. In this paper, we show that this scenario is feasible in terms of the energy Abstract: required for the observed coronal heating and the magnetic energy available in the observed sheared core fields. In a representative active region, from the X-ray and vector field data, we estimate the coronal heating consumption by a selected typical large bright loop, the coronal heating consumption by a typical microflare at the foot of this loop, the frequency of microflares at the foot, and the available magnetic energy in the microflaring core field. We find that: (1) the rate of magnetic energy release to power the microflares at the foot (approx. 6 x 10(ext 25)erg/s) is enough to also power the coronal heating in the body of the extended loop (approx. 2 x l0(exp 25 erg/s), and (2) there is enough stored magnetic energy in the sheared core field to sustain the microflaring and extended loop heating for about a day, which is a typical time for buildup of neutral-line magnetic shear in an active region. This work was funded by the Solar Physics Branch of NASA's Office of Space Science through the SR&T Program and the SEC Guest Investigator Program.

Observing the Roots of Coronal Heating - in the Chromosphere

NASA Astrophysics Data System (ADS)

McIntosh, S. W.; de Pontieu, B.; Hansteen, V. H.; Schrjver, K.

2009-12-01

I will discuss recent results using Hinode/SOT-EIS-XRT, SOHO/SUMER, CRISP (at the Swedish Solar Telescope) and TRACE that provide a direct connection between coronal dynamics and those of the lower atmosphere. We use chromospheric measurements (H-alpha and Ca II 8542 spectral imaging, and Ca II H images), as well as UV spectra (EIS and SUMER), and EUV/X-ray images (XRT and TRACE) to show that faint, high-speed upflows at velocities of 50-100 km/s across a wide range of temperatures from chromospheric (10,000 K), through lower and upper transition region (0.1 to 0.7 MK) and coronal temperatures (2 MK) are associated with significant mass-loading of the corona with hot plasma. Our observations are incompatible with current models in which coronal heating occurs as a result of nanoflares at coronal heights. Instead we suggest that a significant fraction of heating of plasma to coronal temperatures may occur at chromospheric heights in association with jets driven from below (the recently discovered type II spicules). Illustrating the mass and energy transport between the chromosphere, transition region and corona, as deduced from Hinode observations. Convective flows and oscillations in the convection zone and photosphere of the Sun buffet the magnetic field of the Sun. This leads to at least two different kinds of jets in the chromosphere: Type I, and II spicules. Type II spicules drive matter upward violently and likely form when magnetic field reconnects because of stresses introduced by convective flows. A significant fraction of the plasma in type II spicules is heated to coronal temperatures (>1MK), providing the corona with hot plasma. The correlation between the chromospheric and coronal parts of the spicules depends greatly on the viewing angle between the line-of-sight and the direction of the upward flows. Order of magnitude estimates indicate that the mass supplied by type II spicules plays a significant role in supplying the corona with hot plasma.

Evaluating Uncertainties in Coronal Electron Temperature and Radial Speed Measurements Using a Simulation of the Bastille Day Eruption

NASA Astrophysics Data System (ADS)

Reginald, Nelson; St. Cyr, Orville; Davila, Joseph; Rastaetter, Lutz; Török, Tibor

2018-05-01

Obtaining reliable measurements of plasma parameters in the Sun's corona remains an important challenge for solar physics. We previously presented a method for producing maps of electron temperature and speed of the solar corona using K-corona brightness measurements made through four color filters in visible light, which were tested for their accuracies using models of a structured, yet steady corona. In this article we test the same technique using a coronal model of the Bastille Day (14 July 2000) coronal mass ejection, which also contains quiet areas and streamers. We use the coronal electron density, temperature, and flow speed contained in the model to determine two K-coronal brightness ratios at (410.3, 390.0 nm) and (423.3, 398.7 nm) along more than 4000 lines of sight. Now assuming that for real observations, the only information we have for each line of sight are these two K-coronal brightness ratios, we use a spherically symmetric model of the corona that contains no structures to interpret these two ratios for electron temperature and speed. We then compare the interpreted (or measured) values for each line of sight with the true values from the model at the plane of the sky for that same line of sight to determine the magnitude of the errors. We show that the measured values closely match the true values in quiet areas. However, in locations of coronal structures, the measured values are predictably underestimated or overestimated compared to the true values, but can nevertheless be used to determine the positions of the structures with respect to the plane of the sky, in front or behind. Based on our results, we propose that future white-light coronagraphs be equipped to image the corona using four color filters in order to routinely create coronal maps of electron density, temperature, and flow speed.

Solar Hard X-ray Observations with NuSTAR

NASA Astrophysics Data System (ADS)

Marsh, Andrew; Smith, D. M.; Krucker, S.; Hudson, H. S.; Hurford, G. J.; White, S. M.; Mewaldt, R. A.; Harrison, F. A.; Grefenstette, B. W.; Stern, D.

2012-05-01

High-sensitivity imaging of coronal hard X-rays allows detection of freshly accelerated nonthermal electrons at the acceleration site. A few such observations have been made with Yohkoh and RHESSI, but a leap in sensitivity could help pin down the time, place, and manner of reconnection. Around the time of this meeting, the Nuclear Spectroscopic Telescope ARray (NuSTAR), a NASA Small Explorer for high energy astrophysics that uses grazing-incidence optics to focus X-rays up to 80 keV, will be launched. Three weeks will be dedicated to solar observing during the baseline two-year mission. NuSTAR will be 200 times more sensitive than RHESSI in the hard X-ray band. This will allow the following new observations, among others: 1) Extrapolation of the micro/nanoflare distribution by two orders of magnitude down in flux; 2) Search for hard X-rays from network nanoflares (soft X-ray bright points) and evaluation of their role in coronal heating; 3) Discovery of hard X-ray bremsstrahlung from the electron beams driving type III radio bursts, and measurement of their electron spectrum; 4) Hard X-ray studies of polar soft X-ray jets and impulsive solar energetic particle events at the edge of coronal holes; 5) Study of coronal bremsstrahlung from particles accelerated by coronal mass ejections as they are first launched; 6) Study of particles at the coronal reconnection site when flare footpoints and loops are occulted; 7) Search for weak high-temperature coronal plasmas in active regions that are not flaring; and 8) Search for hypothetical axion particles created in the solar core via the hard X-ray signal from their conversion to X-rays in the coronal magnetic field. NuSTAR will also serve as a pathfinder for a future dedicated space mission with enhanced capabilities, such as a satellite version of the FOXSI sounding rocket.

Critical Magnetic Field Strengths for Unipolar Solar Coronal Plumes in Quiet Regions and Coronal Holes?

NASA Astrophysics Data System (ADS)

Avallone, E. A.; Tiwari, S. K.; Panesar, N. K.; Moore, R. L.

2017-12-01

Coronal plumes are sporadic fountain-like structures that are bright in coronal emission. Each is a magnetic funnel rooted in a strong patch of dominant-polarity photospheric magnetic flux surrounded by a predominantly-unipolar magnetic network, either in a quiet region or a coronal hole. The heating processes that make plumes bright evidently involve the magnetic field in the base of the plume, but remain mysterious. Raouafi et al. (2014) inferred from observations that plume heating is a consequence of magnetic reconnection in the base, whereas Wang et al. (2016) showed that plume heating turns on/off from convection-driven convergence/divergence of the base flux. While both papers suggest that the base magnetic flux in their plumes is of mixed polarity, these papers provide no measurements of the abundance and strength of the evolving base flux or consider whether a critical magnetic field strength is required for a plume to become noticeably bright. To address plume production and evolution, we track the plume luminosity and the abundance and strength of the base magnetic flux over the lifetimes of six coronal plumes, using Solar Dynamics Observatory (SDO)/Atmospheric Imaging Assembly (AIA) 171 Å images and SDO/Helioseismic and Magnetic Imager (HMI) line-of-sight magnetograms. Three of these plumes are in coronal holes, three are in quiet regions, and each plume exhibits a unipolar base flux. We track the base magnetic flux over each plume's lifetime to affirm that its convergence and divergence respectively coincide with the appearance and disappearance of the plume in 171 Å images. We tentatively find that plume formation requires enough convergence of the base flux to surpass a field strength of ˜300-500 Gauss, and that quiet Sun and coronal-hole plumes both exhibit the same behavior in the response of their luminosity in 171 Å to the strength of the magnetic field in the base.

The plasma filling factor of coronal bright points. II. Combined EIS and TRACE results

NASA Astrophysics Data System (ADS)

Dere, K. P.

2009-04-01

Aims: In a previous paper, the volumetric plasma filling factor of coronal bright points was determined from spectra obtained with the Extreme ultraviolet Imaging Spectrometer (EIS). The analysis of these data showed that the median plasma filling factor was 0.015. One interpretation of this result was that the small filling factor was consistent with a single coronal loop with a width of 1-2´´, somewhat below the apparent width. In this paper, higher spatial resolution observations with the Transition Region and Corona Explorer (TRACE) are used to test this interpretation. Methods: Rastered spectra of regions of the quiet Sun were recorded by the EIS during operations with the Hinode satellite. Many of these regions were simultaneously observed with TRACE. Calibrated intensities of Fe xii lines were obtained and images of the quiet corona were constructed from the EIS measurements. Emission measures were determined from the EIS spectra and geometrical widths of coronal bright points were obtained from the TRACE images. Electron densities were determined from density-sensitive line ratios measured with EIS. A comparison of the emission measure and bright point widths with the electron densities yielded the plasma filling factor. Results: The median electron density of coronal bright points is 3 × 109 cm-3 at a temperature of 1.6 × 106 K. The volumetric plasma filling factor of coronal bright points was found to vary from 3 × 10-3 to 0.3 with a median value of 0.04. Conclusions: The current set of EIS and TRACE coronal bright-point observations indicate the median value of their plasma filling factor is 0.04. This can be interpreted as evidence of a considerable subresolution structure in coronal bright points or as the result of a single completely filled plasma loop with widths on the order of 0.2-1.5´´ that has not been spatially resolved in these measurements.

Hemispheric asymmetry in coronal hole evolution: Cause of the bashful ballerina?

NASA Astrophysics Data System (ADS)

Mursula, K.; Tlatov, A.; Virtanen, I.

2012-12-01

The magnetic hemisphere prevalent in the solar northern hemisphere has been shown to cover a larger area than in the south for about three years in the declining phase of several solar cycles. Correspondingly, the average field intensity is weaker in the northern hemisphere and the heliospheric current sheet (HCS) is shifted southward at these times. This phenomenon, now called the bashful ballerina, has been verified using several databases and methods, including the in situ observations of the heliospheric magnetic field (HMF) at 1 AU by the OMNI data base, at about 2 AU by the Ulysses probe, and at different radial distances by the Voyager 1 and 2 and Pioneer 10 and 11 probes. The Ulysses observations show that the mean southward shift of the HCS was about 2 degrees in the declining phase of both cycle 22 and cycle 23, although the polar strengths were very different between the two cycles. The HMF observations by the Voyager and Pioneer probes show a very consistent structure of HMF sectors and HCS location in the entire heliosphere, and even beyond the termination shock. Moreover, they suggest a systematic difference in the development of northern and southern polar coronal holes. While the northern coronal holes developed very systematically during all the four solar minima since mid-1970s, the evolution of southern coronal holes was less systematic and delayed with respect to the northern hemisphere. This delay in the evolution of southern coronal holes leads to a larger extent of northern coronal holes and a southward shift of the heliospheric current sheet (the bashful ballerina phenomenon) for a few years in the declining phase of the solar cycle. Here we study direct observations of solar coronal holes and verify this difference in the evolution of coronal holes between the two solar hemispheres, which explains the bashful ballerina phenomenon.

Supra-acetabular line is better than supra-iliac line for coronal balance referencing-a study of perioperative whole spine X-rays in degenerative lumbar scoliosis and ankylosing spondylitis patients.

PubMed

Hey, Hwee Weng Dennis; Kim, Cheung-Kue; Lee, Won-Gyu; Juh, Hyung-Suk; Kim, Ki-Tack

2017-12-01

The aim of spinal deformity correction is to restore the spine's functional alignment by balancing it in both the sagittal and coronal planes. Regardless of posture, the ideal coronal profile is straight, and therefore readily assessable. This study compares two radiological methods to determine which better predicts postoperative standing coronal balance. We conducted a single-center, radiographic comparative study between 2011 and 2015. A total of 199 patients with a mean age of 55.1 years were studied. Ninety patients with degenerative lumbar scoliosis (DLS) and 109 ankylosing spondylitis (AS) were treated with posterior surgery during this period. Baseline clinical and radiographic parameters (sagittal and coronal) were recorded. Comparison was performed between the new supra-acetabular line (central sacral vertical line [CSVL1]) and conventional supra-iliac line (CSVL2) perpendicular methods of coronal balance assessment. These methods were also compared with the gold standard standing C7 plumb line. Each patient underwent standardized operative procedures and had perioperative spine X-rays obtained for assessment of spinal balance. Adjusted multivariate analysis was used to determine predictors of coronal balance. Significant differences in baseline characteristics (age, gender, and radiographic parameters) were found between patients with DLS and AS. CSVL1, CSVL2, and C7 plumb line differed in all the perioperative measurements. These three radiological methods showed a mean right coronal imbalance for both diagnoses in all pre-, intra-, and postoperative radiographs. The magnitude of imbalance was the greatest for CSVL2 followed by CSVL1 and subsequently the C7 plumb line. A larger discrepancy between CSVL and C7 plumb line measurements intraoperatively than those postoperatively suggests a postural effect on these parameters, which is greater for CSVL2. Multivariate analysis identified that in DLS, the preoperative C7 plumb line was predictive of its postoperative value. CSVL1, but not CSVL2, was predictive of the postoperative C7 plumb line in patients with AS. The supra-acetabular line (CSVL1) is better, although not ideal, as compared with the supra-iliac line (CSVL2) in determining coronal balance. Because CSVL1 still cannot be relied on with a high predictive value, it is imperative that future studies continue to identify better intraoperative markers for achieving coronal balance. Copyright © 2017 Elsevier Inc. All rights reserved.

Tourism in New England towns: a threat to the rural fabric

Treesearch

Robert S. Bristow

2007-01-01

A traditional tourist attraction in New England is the classic rural New England town. These small communities have a small-town feel bounded by family farms and wooded lands. These towns are heavily visited during the fall foliage season and during spring maple sugaring operations. The rural character of many New England communities is threatened by a growing...

75 FR 58411 - Medicare Program; Town Hall Meeting on the Physician Compare Web Site, October 27, 2010

Federal Register 2010, 2011, 2012, 2013, 2014

2010-09-24

...] Medicare Program; Town Hall Meeting on the Physician Compare Web Site, October 27, 2010 AGENCY: Centers for... establish a Physician Compare Web site by January 1, 2011. This notice announces a Town Hall meeting to discuss the Physician Compare Web site. The purpose of this Town Hall meeting is to solicit input from...

Assessment of arsenic concentrations in domestic well water, by town, in Maine 2005-09

USGS Publications Warehouse

Nielsen, M.G.; Lombard, P.J.; Schalk, L.F.

2010-01-01

Prior studies have established that approximately 10 percent of domestic wells in Maine have arsenic levels greater than the U.S. Environmental Protection Agency maximum contaminant limit (10 micrograms per liter (ug/L)). Of even greater concern are multiple discoveries of wells with very high arsenic levels (> 500 ug/L) in several areas of the State. A study was initiated to assist the Maine Center for Disease Control and Prevention (ME-CDC) in developing a better understanding of the statewide spatial occurrence of wells with elevated arsenic levels at the individual town level, identify areas of the State that should be targeted for increased efforts to promote well-water testing, and generate data for potential use in predicting areas of the State likely to have very high levels of arsenic. The State's Health and Environmental and Testing Laboratory (HETL) annually analyzes samples from thousands of domestic wells for arsenic. Results of arsenic analyses of domestic well water submitted to the HETL from 2005 to 2009 were screened and organized, by town, in order to summarize the results for all towns with samples submitted to the HETL. In order to preserve the privacy of well owners, the screening and organization of samples was conducted in the offices of the ME-CDC, following applicable Maine and United States laws, rules, and privacy policies. After screening, the database contained samples from 531 towns in Maine and from 11,111 individual wells. Of those towns, 385 had samples from 5 or more individual wells, 174 towns had samples from 20 or more individual wells, and 49 towns had samples from 60 or more wells. These samples, because they were submitted by homeowners and were not part of a random sample, may not be representative of all wells in a given area. The minimum, maximum, and median arsenic values for the towns with five or more samples were calculated, and the maximum and median values were mapped for the State. The percentages of samples exceeding 10, 50, 100, and 500 ug/L were calculated for the 174 towns with 20 or more sampled wells, and statewide maps were prepared for each of these categories. More than 25 percent of the sampled wells in 44 towns exceeded 10 ug/L. Many fewer towns had wells with samples that exceeded the 50, 100, or 500 ug/L categories. For 19 towns, more than 10 percent of the sampled wells had arsenic concentrations that exceeded 50 ug/L, and in 45 towns, 1 percent or more exceeded 100 ug/L. Of these, Surry in Hancock County had 120 wells tested, and 23 percent of those wells had arsenic concentrations that exceeded 100 ug/L, which is a much higher rate than for other towns. In only four towns (Danforth in Washington County, Surry and Blue Hill in Hancock County, and Woolwich in Sagadahoc County), 1 percent or more of the sampled wells had arsenic concentrations greater than 500 ug/L during 2005-09. The distribution of high arsenic concentrations in wells follows some geographic patterns, which are generally geologically controlled. There are clusters or belts of towns with high arsenic concentrations (> 50 ug/L), such as in southern coastal areas, the Kennebec County area, and towns along the central coastal part of Maine. In contrast, there are areas of the State with low arsenic concentrations, such as the northernmost towns, as well as towns in the western and west-central areas. There appear to be three distinct large-scale areas of high concentrations of arsenic in groundwater-one in southern coastal areas, one in central Kennebec County, and one in the town of Ellsworth (Hancock County) and the surrounding areas. In addition, several smaller clusters of isolated high concentrations of arsenic in groundwater exist. Earlier testing has identified other clusters of very high arsenic concentrations in groundwater in the towns of Northport, Buxton/Hollis, and Waldoboro, but those samples were collected before 2005 and did not factor in this analysis.

Data on microscale atmospheric pollution of Bolshoy Kamen town (Primorsky region, Russia)

NASA Astrophysics Data System (ADS)

Kholodov, Aleksei; Ugay, Sergey; Drozd, Vladimir; Maiss, Natalia; Golokhvast, Kirill

2017-10-01

The paper discusses the study of atmospheric particulate matter of Bolshoy Kamen town by means of laser granulometry of snow water samples. Snow sampling points were selected close to major enterprises, along the main streets and roads of the town and in the residential area. The near-ground layer of atmospheric air of the town contains particulate matter of three main size classes: under 10 microns, 10-50 microns and over 700 microns. It is shown that the atmosphere of this town is lightly polluted with particles under 10 μm (PM10). Only in 5 sampling points out of 11 we found microparticles potentially hazardous to human health in significant quantities - from 16.2% to 34.6%. On the most territory of the town large particles (over 400 μm) dominate reaching 79.2%. We can conclude that judging by the particle size analysis of snow water samples Bolshoy Kamen town can be considered safe in terms of presence of particles under 10 μm (PM10) in the atmosphere.

Age at menarche: the influence of environmental conditions

NASA Astrophysics Data System (ADS)

Saar, E.; Shalev, C.; Dalal, I.; Sod-Moriah, U. A.

1988-03-01

Age at menarche was studied by the recollection method in two groups of Causasian Jewish high school girls, inhabitants of two towns in Israel, Safad and Elat. The two towns differ mainly in climatic conditions. The age at menarche was found to be significantly lower ( P<0.02) in the hot town of Elat than in the temperate town of Safad: 13.30±1.21 and 13.58±0.9 years, respectively (mean ±SD). A significant association was found between the age at menarche and the town in which the girls lived. Accordingly, in the hot town of Elat, the percentage of girls who had their first menstrual cycle by the age of 12 years and earlier, was more than double that of the girls in Safad (17.9% and 7.1%, respectively). It is concluded that the environmental temperature, with or without any possible interaction of humidity, is probably responsible for the tendency for an earlier onset of menarche in girls living in the hot town of Elat.

Spatial Analysis of Urban Master Plans of Towns in North-Eastern Poland in the Context of Urban Revalorisation

NASA Astrophysics Data System (ADS)

Zagroba, Marek; Klopotowski, Maciej

2017-12-01

The research subject raised in this study is the urban structure of small towns in Warmia, a region rich in history, situated in the north-eastern Poland. This area, together with the neighbouring region of Mazury, is referred to as the Land of a Thousand Lakes. The historical events, such as the conquest of this territory by the Teutonic Order in 13th century, gave rise to the foundation of twelve towns in Warmia, which have survived until our time. Of these settlements, only one, which is Olsztyn, grew to a larger size over the centuries and eventually became the capital of Warmia. The others are still small towns, with a population from a few to less than twenty thousand inhabitants. The policy and economic goals of the Teutonic Order underlay the spread of a uniform type of urban master plan in the entire region. The establishment of urban centres was dictated by military considerations - all towns had fortified castles and were 15-30 km distant from one another, which stemmed from the organisation of the Teutonic State. The location of new towns in Warmia coincided in time with the general urban planning principles governing urban development in the Middle Ages. The medieval towns, which grew on the foundations of ancient cultures, were developed on a regular grid of streets, delineating land lots for compact town houses and a central square serving as a market place. Within this structure, the town’s most significant spatial dominants, such as a town hall, a church and a fortified castle, were situated. The castle often stood on the outskirts of a town, as it had to be connected to the town’s fortifications. The location of medieval towns in Warmia proceeded according to a similar concept. All these towns are distinguished by characteristically medieval, regular urban layouts, which - while being similar - have certain intrinsic features. Differences can be seen in the design of main streets, the size and proportions of market squares, the ways in which land parcels were developed as well as the location of public buildings. However, the space occupied by the old town has remained dominant in all these urban developments. This, to a large extent, explains the synthetic character of the following research. Spatial analysis of urban patterns developed in the twelve towns of Warmia was the principal objective of this study. Another aim was to confirm the hypothesis that medieval urban structures in Warmia (their old town’s area) are the manifestation of the historical identity of these towns and bear some influence on their contemporary development. The conclusions drawn from the investigation, its objectives and the method employed, focus on the connections between the original functions of old towns with the modern-day needs and aspirations to further the towns’ development whilst preserving the historic heritage. Processes designed in line with the above recommendations should eliminate threats to the structure of developed areas and the whole town’s image. Another objective should be to improve the composition-related and aesthetic values of the inner-town space.

Reconstructing the Morphology of an Evolving Coronal Mass Ejection

DTIC Science & Technology

2009-01-01

694, 707 Wood, B. E., Howard, R. A ., Thernisien, A ., Plunkett, S. P., & Socker, D. G. 2009b, Sol. Phys., 259, 163 Wood, B. E., Karovska , M., Chen, J...Reconstructing the Morphology of an Evolving Coronal Mass Ejection B. E. Wood, R. A . Howard, D. G. Socker Naval Research Laboratory, Space Science...mission, we empirically reconstruct the time-dependent three-dimensional morphology of a coronal mass ejection (CME) from 2008 June 1, which exhibits

Observational Features of Equatorial Coronal Hole Jets

DTIC Science & Technology

2010-02-10

0 “Esplorazione del Sistema Solare ”. Some images are produced by FESTIVAL, collaborative project managed by IAS and supported by CNES, which is a...km s−1, while the deceleration rate appears to be about 0.11 km s−2, less than solar gravity. The average jet visibility time is about 30 minutes...differences between polar and equatorial coronal hole jets. Keywords. Coronal holes, jets 1 Introduction The STEREO ( Solar TErrestrial RElations

Culex coronator in coastal Georgia and South Carolina.

PubMed

Moulis, Robert A; Russell, Jennifer D; Lewandowski, Henry B; Thompson, Pamela S; Heusel, Jeffrey L

2008-12-01

In 2007, adult Culex coronator were collected in Chatham County, Georgia, and Jasper County, South Carolina, during nuisance and disease vector surveillance efforts. A total of 75 specimens of this species were collected at 8 widely separated locations in Chatham County, Georgia, and 4 closely situated sites in Jasper County, South Carolina. These represent the first Atlantic coastal records of this species in Georgia and the first confirmed records of Cx. coronator in South Carolina.

An observation of prominence condensation out of a coronal void

NASA Astrophysics Data System (ADS)

Wagner, W. J.; Newkirk, G., Jr.; Schmidt, H. U.

1983-02-01

Photographic averaging of cine-camera data-frames from the 7 March 1970 eclipse provided a record of the inner white light corona with unusually high resolution for low-contrast features. The authors report that a coronal void, similar to high corona structures associated with prominence formation (MacQueen et al., 1983), extended low into the corona. During eclipse totality, a coronal rain prominence condensed from the base of the void.

A Next-Generation Model of the Corona and Solar Wind

DTIC Science & Technology

2011-03-31

2007. The Sun was very quiet during this time. An extended coronal hole is visible in the observations and the simulation. (d) July 19, 2008...those synthesized from our model for August 27, 1996, when the “Elephant’s trunk” equatorial coronal hole was visible. To make a quantitative...especially the coronal hole regions, agree reasonably well. Figure 3 shows comparisons of simulated and actual emission for four other time periods. Frame (a

Coronae on stars

NASA Technical Reports Server (NTRS)

Haisch, B. M.

1986-01-01

Three lines of evidence are noted to point to a flare heating source for stellar coronae: a strong correlation between time-averaged flare energy release and coronal X-ray luminosity, the high temperature flare-like component of the spectral signature of coronal X-ray emission, and the observed short time scale variability that indicates continuous flare activity. It is presently suggested that flares may represent only the extreme high energy tail of a continuous distribution of coronal energy release events.

Free Magnetic Energy and Coronal Heating

NASA Technical Reports Server (NTRS)

Winebarger, Amy; Moore, Ron; Falconer, David

2012-01-01

Previous work has shown that the coronal X-ray luminosity of an active region increases roughly in direct proportion to the total photospheric flux of the active region's magnetic field (Fisher et al. 1998). It is also observed, however, that the coronal luminosity of active regions of nearly the same flux content can differ by an order of magnitude. In this presentation, we analyze 10 active regions with roughly the same total magnetic flux. We first determine several coronal properties, such as X-ray luminosity (calculated using Hinode XRT), peak temperature (calculated using Hinode EIS), and total Fe XVIII emission (calculated using SDO AIA). We present the dependence of these properties on a proxy of the free magnetic energy of the active region

MHD shocks in coronal mass ejections

NASA Technical Reports Server (NTRS)

Steinolfson, R. S.

1991-01-01

The primary objective of this research program is the study of the magnetohydrodynamic (MHD) shocks and nonlinear simple waves produced as a result of the interaction of ejected lower coronal plasma with the ambient corona. The types of shocks and nonlinear simple waves produced for representative coronal conditions and disturbance velocities were determined. The wave system and the interactions between the ejecta and ambient corona were studied using both analytic theory and numerical solutions of the time-dependent, nonlinear MHD equations. Observations from the SMM coronagraph/polarimeter provided both guidance and motivation and are used extensively in evaluating the results. As a natural consequence of the comparisons with the data, the simulations assisted in better understanding the physical interactions in coronal mass ejections (CME's).

Hybrid Stars and Coronal Evolution

NASA Technical Reports Server (NTRS)

Mushotzky, Richard (Technical Monitor); Dupree, Andrea K.

2004-01-01

This program addresses the evolution of stellar coronas by comparing a solar-like corona in the supergiant Dra (G2 Ib-IIa) to the corona in the allegedly more evolved state of a hybrid star, TrA (K2 11-111). Because the hybrid star has a massive wind, it appears likely that the corona will be cooler and less dense as the magnetic loop structures are no longer closed. By analogy with solar coronal holes, when the topology of the magnetic field is configured with open magnetic structures, both the coronal temperature and density are lower than in atmospheres dominated by closed loops. The hybrid stars assume a pivotal role in the definition of coronal evolution, atmospheric heating processes and mechanisms to drive winds of cool stars.

Energy balance of stellar coronae. III - Effect of stellar mass and radius

NASA Technical Reports Server (NTRS)

Hammer, R.

1984-01-01

A homologous transformation is derived which permits the application of the numerical coronal models of Hammer from a star with solar mass and radius to other stars. This scaling requires a few approximations concerning the lower boundary conditions and the temperature dependence of the conductivity and emissivity. These approximations are discussed and found to be surprisingly mild. Therefore, the scaling of the coronal models to other stars is rather accurate; it is found to be particularly accurate for main-sequence stars. The transformation is used to derive an equation that gives the maximum temperature of open coronal regions as a function of stellar mass and radius, the coronal heating flux, and the characteristic damping length over which the corona is heated.

Application of computer-aided three-dimensional skull model with rapid prototyping technique in repair of zygomatico-orbito-maxillary complex fracture.

PubMed

Li, Wei Zhong; Zhang, Mei Chao; Li, Shao Ping; Zhang, Lei Tao; Huang, Yu

2009-06-01

With the advent of CAD/CAM and rapid prototyping (RP), a technical revolution in oral and maxillofacial trauma was promoted to benefit treatment, repair of maxillofacial fractures and reconstruction of maxillofacial defects. For a patient with zygomatico-facial collapse deformity resulting from a zygomatico-orbito-maxillary complex (ZOMC) fracture, CT scan data were processed by using Mimics 10.0 for three-dimensional (3D) reconstruction. The reduction design was aided by 3D virtual imaging and the 3D skull model was reproduced using the RP technique. In line with the design by Mimics, presurgery was performed on the 3D skull model and the semi-coronal incision was taken for reduction of ZOMC fracture, based on the outcome from the presurgery. Postoperative CT and images revealed significantly modified zygomatic collapse and zygomatic arch rise and well-modified facial symmetry. The CAD/CAM and RP technique is a relatively useful tool that can assist surgeons with reconstruction of the maxillofacial skeleton, especially in repairs of ZOMC fracture.

78 FR 8179 - Proposed Flood Hazard Determinations

Federal Register 2010, 2011, 2012, 2013, 2014

2013-02-05

... panels of experts in hydrology, hydraulics, and other pertinent sciences established to review.../dnr/water/7359.htm Town of Medaryville Town Hall, 409 East Main Street, Medaryville, IN 47957. Town of...

Promoting small towns for rural development: a view from Nepal.

PubMed

Bajracharya, B N

1995-06-01

Two small villages in Nepal are the subjects of case studies that illustrate the role of small towns in provision of services, employment, and market operations. Some general findings are that small towns act as service centers for distribution of basic essential goods such as food grains, salt, kerosene, and fabric for hill and mountain areas. The role of small towns as market centers and in the provision of employment is limited. In resource-poor areas small towns are less diversified. Towns with agricultural surpluses are more developed. Small hill towns satisfy consumption rather than production needs. The growth of rural areas and towns in rural areas in Nepal is dependent on arable land and levels of production in hill areas. Limited land and low levels of production have an adverse impact. Movement of people, goods, and services is limited by difficult terrain and lack of access to good roads. Variability in access to off-farm jobs and services available in small towns varies with ethnicity and place of residence. The best development strategy for small towns in Nepal is market-oriented territorial development, which retains surpluses in the local area and integrates markets in the larger economy. The strategy would decentralize planning into small territorial units that include both small towns and groups of villages, provide institutional support for the rural poor, expand off-farm employment, and include investment in region-serving functions. Subsistence agriculture needs to include diversification of high value cash crops based on local comparative advantage suitable for hill climate and terrain. Small farmers must produce both cash and subsistence crops. Government should provide market space and paved areas, weighing facilities, and overnight storage facilities. Products would be processed at the village level. Subdistricts must be established according to spatial and social linkages between villages and the service center and coordinated at the district level. Group marketing, transport to large urban centers, and agricultural technical services are needed.

Infrared coronal emission lines and the possibility of their maser emission in Seyfert nuclei

NASA Technical Reports Server (NTRS)

Greenhouse, Matthew A.; Feldman, Uri; Smith, Howard A.; Klapisch, Marcel; Bhatia, Anand K.; Bar-Shalom, Abi

1993-01-01

Energetic emitting regions have traditionally been studied via x-ray, UV and optical emission lines of highly ionized intermediate mass elements. Such lines are often referred to as 'coronal lines' since the ions, when produced by collisional ionization, reach maximum abundance at electron temperatures of approx. 10(exp 5) - 10(exp 6) K typical of the sun's upper atmosphere. However, optical and UV coronal lines are also observed in a wide variety of Galactic and extragalactic sources including the Galactic interstellar medium, nova shells, supernova remnants, galaxies and QSOs. Infrared coronal lines are providing a new window for observation of energetic emitting regions in heavily dust obscured sources such as infrared bright merging galaxies and Seyfert nuclei and new opportunities for model constraints on physical conditions in these sources. Unlike their UV and optical counterparts, infrared coronal lines can be primary coolants of collisionally ionized plasmas with 10(exp 4) less than T(sub e)(K) less than 10(exp 6) which produce little or no optical or shorter wavelength coronal line emission. In addition, they provide a means to probe heavily dust obscured emitting regions which are often inaccessible to optical or UV line studies. In this poster, we provide results from new model calculations to support upcoming Infrared Space Observatory (ISO) and current ground-based observing programs involving infrared coronal emission lines in AGN. We present a complete list of infrared (lambda greater than 1 micron) lines due to transitions within the ground configurations 2s(2)2p(k) and 3s(2)3p(k) (k = 1 to 5) or the first excited configurations 2s2p and 3s3p of highly ionized (x greater than or equal to 100 eV) astrophysically abundant (n(X)/n(H) greater than or equal to 10(exp -6)) elements. Included are approximately 74 lines in ions of O, Ne, Na, Mg, Al, Si, S, Ar, Ca, Fe, and Ni spanning a wavelength range of approximately 1 - 280 microns. We present new results from detailed balance calculations, new critical densities for collisional de-excitation, intrinsic photon rates, branching ratios, and excitation temperatures for the majority of the compiled transitions. The temperature and density parameter space for dominant cooling via infrared coronal lines is presented, and the relationship of infrared to optical coronal lines is discussed.

Effect of alignment changes on sagittal and coronal socket reaction moment interactions in transtibial prostheses.

PubMed

Kobayashi, Toshiki; Orendurff, Michael S; Zhang, Ming; Boone, David A

2013-04-26

Alignment is important for comfortable and stable gait of lower-limb prosthesis users. The magnitude of socket reaction moments in the multiple planes acting simultaneously upon the residual limb may be related to perception of comfort in individuals using prostheses through socket interface pressures. The aim of this study was to investigate the effect of prosthetic alignment changes on sagittal and coronal socket reaction moment interactions (moment-moment curves) and to characterize the curves in 11 individuals with transtibial amputation using novel moment-moment interaction parameters measured by plotting sagittal socket reaction moments versus coronal ones under various alignment conditions. A custom instrumented prosthesis alignment component was used to measure socket reaction moments during walking. Prosthetic alignment was tuned to a nominally aligned condition by a prosthetist, and from this position, angular (3° and 6° of flexion, extension, abduction or adduction of the socket) and translational (5mm and 10mm of anterior, posterior, medial or lateral translation of the socket) alignment changes were performed in either the sagittal or the coronal plane in a randomized manner. A total of 17 alignment conditions were tested. Coronal angulation and translation alignment changes demonstrated similar consistent changes in the moment-moment curves. Sagittal alignment changes demonstrated more complex changes compared to the coronal alignment changes. Effect of sagittal angulations and translations on the moment-moment curves was different during 2nd rocker (mid-stance) with extension malalignment appearing to cause medio-lateral instability. Presentation of coronal and sagittal socket reaction moment interactions may provide useful visual information for prosthetists to understand the biomechanical effects of malalignment of transtibial prostheses. Copyright © 2013 Elsevier Ltd. All rights reserved.

Eruptions that Drive Coronal Jets in a Solar Active Region

NASA Technical Reports Server (NTRS)

Sterling, Alphonse C.; Moore, Ronald L.; Falconer, David A.; Panesar, Navdeep K.; Akiyama, Sachiko; Yashiro, Seiji; Gopalswamy, Nat

2016-01-01

Solar coronal jets are common in both coronal holes and in active regions (e.g., Shibata et al. 1992, Shimojo et al. 1996, Cirtain et al. 2007. Savcheva et al. 2007). Recently, Sterling et al. (2015), using data from Hinode/XRT and SDO/AIA, found that coronal jets originating in polar coronal holes result from the eruption of small-scale filaments (minifilaments). The jet bright point (JBP) seen in X-rays and hotter EUV channels off to one side of the base of the jet's spire develops at the location where the minifilament erupts, consistent with the JBPs being miniature versions of typical solar flares that occur in the wake of large-scale filament eruptions. Here we consider whether active region coronal jets also result from the same minifilament-eruption mechanism, or whether they instead result from a different mechanism (e.g. Yokoyama & Shibata 1995). We present observations of an on-disk active region (NOAA AR 11513) that produced numerous jets on 2012 June 30, using data from SDO/AIA and HMI, and from GOES/SXI. We find that several of these active region jets also originate with eruptions of miniature filaments (size scale 20'') emanating from small-scale magnetic neutral lines of the region. This demonstrates that active region coronal jets are indeed frequently driven by minifilament eruptions. Other jets from the active region were also consistent with their drivers being minifilament eruptions, but we could not confirm this because the onsets of those jets were hidden from our view. This work was supported by funding from NASA/LWS, NASA/HGI, and Hinode. A full report of this study appears in Sterling et al. (2016).

Magnetic Untwisting in Jets that Go into the Outer Solar Corona in Polar Coronal Holes

NASA Astrophysics Data System (ADS)

Moore, Ronald L.; Sterling, Alphonse C.; Falconer, David

2014-06-01

We present results from a study of 14 jets that were observed in SDO/AIA EUV movies to erupt in the Sun’s polar coronal holes. These jets were similar to the many other jets that erupt in coronal holes, but reached higher than the vast majority, high enough to be observed in the outer corona beyond 2 solar radii from Sun center by the SOHO/LASCO/C2 coronagraph. We illustrate the characteristic structure and motion of these high-reaching jets by showing observations of two representative jets. We find that (1) the speed of the jet front from the base of the corona out to 2-3 solar radii is typically several times the sound speed in jets in coronal holes, (2) each high-reaching jet displays unusually large rotation about its axis (spin) as it erupts, and (3) in the outer corona, many jets display lateral swaying and bending of the jet axis with an amplitude of a few degrees and a period of order 1 hour. From these observations we infer that these jets are magnetically driven, propose that the driver is a magnetic-untwisting wave that is basically a large-amplitude (non-linear) torsional Alfven wave that is put into the open magnetic field in the jet by interchange reconnection as the jet erupts, and estimate that the magnetic-untwisting wave loses most of its energy before reaching the outer corona. These observations of high-reaching coronal jets suggest that the torsional magnetic waves observed in Type-II spicules can similarly dissipate in the corona and thereby power much of the coronal heating in coronal holes and quiet regions. This work is funded by the NASA/SMD Heliophysics Division’s Living With a Star Targeted Research & Technology Program.

DICHOTOMY OF SOLAR CORONAL JETS: STANDARD JETS AND BLOWOUT JETS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moore, Ronald L.; Cirtain, Jonathan W.; Sterling, Alphonse C.

2010-09-01

By examining many X-ray jets in Hinode/X-Ray Telescope coronal X-ray movies of the polar coronal holes, we found that there is a dichotomy of polar X-ray jets. About two thirds fit the standard reconnection picture for coronal jets, and about one third are another type. We present observations indicating that the non-standard jets are counterparts of erupting-loop H{alpha} macrospicules, jets in which the jet-base magnetic arch undergoes a miniature version of the blowout eruptions that produce major coronal mass ejections. From the coronal X-ray movies we present in detail two typical standard X-ray jets and two typical blowout X-ray jetsmore » that were also caught in He II 304 A snapshots from STEREO/EUVI. The distinguishing features of blowout X-ray jets are (1) X-ray brightening inside the base arch in addition to the outside bright point that standard jets have, (2) blowout eruption of the base arch's core field, often carrying a filament of cool (T {approx} 10{sup 4} - 10{sup 5} K) plasma, and (3) an extra jet-spire strand rooted close to the bright point. We present cartoons showing how reconnection during blowout eruption of the base arch could produce the observed features of blowout X-ray jets. We infer that (1) the standard-jet/blowout-jet dichotomy of coronal jets results from the dichotomy of base arches that do not have and base arches that do have enough shear and twist to erupt open, and (2) there is a large class of spicules that are standard jets and a comparably large class of spicules that are blowout jets.« less

Simulations of Solar Jets Confined by Coronal Loops

NASA Technical Reports Server (NTRS)

Wyper, P. F.; De Vore, C. R.

2016-01-01

Coronal jets are collimated, dynamic events that occur over a broad range of spatial scales in the solar corona. In the open magnetic field of coronal holes, jets form quasi-radial spires that can extend far out into the heliosphere, while in closed-field regions the jet outflows are confined to the corona. We explore the application of the embedded-bipole model to jets occurring in closed coronal loops. In this model, magnetic free energy is injected slowly by footpoint motions that introduce twist within the closed dome of the jet source region, and is released rapidly by the onset of an ideal kink-like instability. Two length scales characterize the system: the width (N) of the jet source region and the footpoint separation (L) of the coronal loop that envelops the jet source. We find that both the conditions for initiation and the subsequent dynamics are highly sensitive to the ratio L/N. The longest-lasting and most energetic jets occur along long coronal loops with large L/N ratios, and share many of the features of open-field jets, while smaller L/N ratios produce shorter-duration, less energetic jets that are affected by reflections from the far-loop footpoint. We quantify the transition between these behaviors and show that our model replicates key qualitative and quantitative aspects of both quiet Sun and active-region loop jets. We also find that there connection between the closed dome and surrounding coronal loop is very extensive: the cumulative reconnected flux at least matches the total flux beneath the dome for small L/N, and is more than double that value for large L/N.

Evaluation of the Minifilament-Eruption Scenario for Solar Coronal Jets in Polar Coronal Holes

NASA Technical Reports Server (NTRS)

Baikie, Tomi K.; Sterling, Alphonse C.; Falconer, David; Moore, Ronald L.; Savage, Sabrina L.

2016-01-01

Solar coronal jets are suspected to result from magnetic reconnection low in the Sun's atmosphere. Sterling et al. (2015) looked as 20 jets in polar coronal holes, using X-ray images from the Hinode/X-Ray Telescope (XRT) and EUV images from the Solar Dynamics Observatory (SDO) Atmospheric Imaging Assembly (AIA). They suggested that each jet was driven by the eruption of twisted closed magnetic field carrying a small-scale filament, which they call a 'minifilament', and that the jet was produced by reconnection of the erupting field with surrounding open field. In this study, we carry out a more extensive examination of polar coronal jets. From 180 hours of XRT polar coronal hole observations spread over two years (2014-2016), we identified 130 clearly-identifiable X-ray jet events and thus determined an event rate of over 17 jets per day per in the Hinode/XRT field of view. From the broader set, we selected 25 of the largest and brightest events for further study in AIA 171, 193, 211, and 304 Angstrom images. We find that at least the majority of the jets follow the minifilament-eruption scenario, although for some cases the evolution of the minifilament in the onset of its eruption is more complex than presented in the simplified schematic of Sterling et al. (2015). For all cases in which we could make a clear determination, the spire of the X-ray jet drifted laterally away from the jet-base-edge bright point; this spire drift away from the bright point is consistent with expectations of the minifilament-eruption scenario for coronal-jet production. This work was supported with funding from the NASA/MSFC Hinode Project Office, and from the NASA HGI program.

SIMULATIONS OF SOLAR JETS CONFINED BY CORONAL LOOPS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wyper, P. F.; DeVore, C. R., E-mail: peter.f.wyper@nasa.gov, E-mail: c.richard.devore@nasa.gov

Coronal jets are collimated, dynamic events that occur over a broad range of spatial scales in the solar corona. In the open magnetic field of coronal holes, jets form quasi-radial spires that can extend far out into the heliosphere, while in closed-field regions the jet outflows are confined to the corona. We explore the application of the embedded-bipole model to jets occurring in closed coronal loops. In this model, magnetic free energy is injected slowly by footpoint motions that introduce twist within the closed dome of the jet source region, and is released rapidly by the onset of an idealmore » kink-like instability. Two length scales characterize the system: the width (N) of the jet source region and the footpoint separation (L) of the coronal loop that envelops the jet source. We find that both the conditions for initiation and the subsequent dynamics are highly sensitive to the ratio L/N. The longest-lasting and most energetic jets occur along long coronal loops with large L/N ratios, and share many of the features of open-field jets, while smaller L/N ratios produce shorter-duration, less energetic jets that are affected by reflections from the far-loop footpoint. We quantify the transition between these behaviors and show that our model replicates key qualitative and quantitative aspects of both quiet Sun and active-region loop jets. We also find that the reconnection between the closed dome and surrounding coronal loop is very extensive: the cumulative reconnected flux at least matches the total flux beneath the dome for small L/N, and is more than double that value for large L/N.« less

Effect of microthreads on coronal bone healing of narrow-diameter implants with reverse-tapered design in beagle dogs.

PubMed

Chang, Yun-Young; Kim, Su-Hwan; Park, Keun-Oh; Yun, Jeong-Ho

2017-12-01

The objective of this study was to investigate the effect of microthreads on the coronal bone healing of narrow-diameter implants with reverse-tapered design. A total of 52 implants were classified into two groups according to presence or absence of coronal microthreads, the reverse-tapered narrow-diameter implant (RTN) group, and the reverse-tapered narrow-diameter implant with microthreads (RTNM) group. The implants were installed in split-mouth design in the edentulous mandible of six dogs. Three animals were sacrificed at 4 weeks and three at 8 weeks. Resonance frequency analysis, bone measurement using microcomputed tomography (micro-CT), removal torque test, and histometric analysis were performed. No significant differences in implant stability quotient value were observed between the groups at baseline, 4 weeks, or 8 weeks. Bone measurement using micro-CT showed that bone-implant contact volume (BICV) and bone-implant contact volume ratio (BICVR) in the coronal part of RTNM were statistically higher than those in RTN at 4 and 8 weeks. Histometric analysis showed statistically higher bone-implant contact length (BICL) in the coronal part of RTNM than in RTN at 4 weeks; however, bone-implant contact ratio (BICR) was not significantly different between the groups. At 8 weeks, the BICL and BICR did not differ significantly between the groups. Removal torque test showed no significant differences between the groups at 4 and 8 weeks. The microthreads might facilitate more coronal bone-implant contact due to increased surface areas at an early healing phase; however, they did not significantly affect coronal bone healing at 8 weeks. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

ANALYSIS OF CORONAL RAIN OBSERVED BY IRIS , HINODE /SOT, AND SDO /AIA: TRANSVERSE OSCILLATIONS, KINEMATICS, AND THERMAL EVOLUTION

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kohutova, P.; Verwichte, E., E-mail: p.kohutova@warwick.ac.uk

Coronal rain composed of cool plasma condensations falling from coronal heights along magnetic field lines is a phenomenon occurring mainly in active region coronal loops. Recent high-resolution observations have shown that coronal rain is much more common than previously thought, suggesting its important role in the chromosphere-corona mass cycle. We present the analysis of MHD oscillations and kinematics of the coronal rain observed in chromospheric and transition region lines by the Interface Region Imaging Spectrograph (IRIS) , the Hinode Solar Optical Telescope (SOT), and the Solar Dynamics Observatory ( SDO) Atmospheric Imaging Assembly (AIA). Two different regimes of transverse oscillationsmore » traced by the rain are detected: small-scale persistent oscillations driven by a continuously operating process and localized large-scale oscillations excited by a transient mechanism. The plasma condensations are found to move with speeds ranging from few km s{sup −1} up to 180 km s{sup −1} and with accelerations largely below the free-fall rate, likely explained by pressure effects and the ponderomotive force resulting from the loop oscillations. The observed evolution of the emission in individual SDO /AIA bandpasses is found to exhibit clear signatures of a gradual cooling of the plasma at the loop top. We determine the temperature evolution of the coronal loop plasma using regularized inversion to recover the differential emission measure (DEM) and by forward modeling the emission intensities in the SDO /AIA bandpasses using a two-component synthetic DEM model. The inferred evolution of the temperature and density of the plasma near the apex is consistent with the limit cycle model and suggests the loop is going through a sequence of periodically repeating heating-condensation cycles.« less

The Coronal Analysis of SHocks and Waves (CASHeW) framework

NASA Astrophysics Data System (ADS)

Kozarev, Kamen A.; Davey, Alisdair; Kendrick, Alexander; Hammer, Michael; Keith, Celeste

2017-11-01

Coronal bright fronts (CBF) are large-scale wavelike disturbances in the solar corona, related to solar eruptions. They are observed (mostly in extreme ultraviolet (EUV) light) as transient bright fronts of finite width, propagating away from the eruption source location. Recent studies of individual solar eruptive events have used EUV observations of CBFs and metric radio type II burst observations to show the intimate connection between waves in the low corona and coronal mass ejection (CME)-driven shocks. EUV imaging with the atmospheric imaging assembly instrument on the solar dynamics observatory has proven particularly useful for detecting large-scale short-lived CBFs, which, combined with radio and in situ observations, holds great promise for early CME-driven shock characterization capability. This characterization can further be automated, and related to models of particle acceleration to produce estimates of particle fluxes in the corona and in the near Earth environment early in events. We present a framework for the coronal analysis of shocks and waves (CASHeW). It combines analysis of NASA Heliophysics System Observatory data products and relevant data-driven models, into an automated system for the characterization of off-limb coronal waves and shocks and the evaluation of their capability to accelerate solar energetic particles (SEPs). The system utilizes EUV observations and models written in the interactive data language. In addition, it leverages analysis tools from the SolarSoft package of libraries, as well as third party libraries. We have tested the CASHeW framework on a representative list of coronal bright front events. Here we present its features, as well as initial results. With this framework, we hope to contribute to the overall understanding of coronal shock waves, their importance for energetic particle acceleration, as well as to the better ability to forecast SEP events fluxes.

CORONAL AND CHROMOSPHERIC SIGNATURES OF LARGE-SCALE DISTURBANCES ASSOCIATED WITH A MAJOR SOLAR ERUPTION

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zong, Weiguo; Dai, Yu, E-mail: ydai@nju.edu.cn

We present both coronal and chromospheric observations of large-scale disturbances associated with a major solar eruption on 2005 September 7. In the Geostationary Operational Environmental Satellites/Solar X-ray Imager (SXI), arclike coronal brightenings are recorded propagating in the southern hemisphere. The SXI front shows an initially constant speed of 730 km s{sup −1} and decelerates later on, and its center is near the central position angle of the associated coronal mass ejection (CME) but away from the flare site. Chromospheric signatures of the disturbances are observed in both Mauna Loa Solar Observatory (MLSO)/Polarimeter for Inner Coronal Studies Hα and MLSO/Chromospheric Helium Imore » Imaging Photometer He i λ10830 and can be divided into two parts. The southern signatures occur in regions where the SXI front sweeps over, with the Hα bright front coincident with the SXI front, while the He i dark front lags the SXI front but shows a similar kinematics. Ahead of the path of the southern signatures, oscillations of a filament are observed. The northern signatures occur near the equator, with the Hα and He i fronts coincident with each other. They first propagate westward and then deflect to the north at the boundary of an equatorial coronal hole. Based on these observational facts, we suggest that the global disturbances are associated with the CME lift-off and show a hybrid nature: a mainly non-wave CME flank nature for the SXI signatures and the corresponding southern chromospheric signatures, and a shocked fast-mode coronal MHD wave nature for the northern chromospheric signatures.« less

Asymmetric C7 pedicle subtraction osteotomy for correction of rigid cervical coronal imbalance secondary to post-traumatic heterotopic ossification: a case report, description of a novel surgical technique, and literature review.

PubMed

Theologis, Alexander A; Bellevue, Kate D; Qamirani, Erion; Ames, Christopher P; Deviren, Vedat

2017-05-01

Deformities of the cervical spine are uncommon in the coronal plane. In this report, a unique case of a 31-year-old male with a fixed, 30° left coronal deformity due to heterotopic ossification 3 years status post poly-trauma was treated with an asymmetric C7 pedicle subtraction osteotomy (PSO). Case report. Pre-operatively, the patient had a fixed 45-degree left tilt of his neck and radiographs demonstrated a rigid 30° scoliosis, 7 cm coronal imbalance, and 4 cm negative sagittal balance, diffuse bridging bone between the spinous processes and the facet joints of C5 to T1 bilaterally. An asymmetric C7 PSO with C2-T3 posterior spinal fusion was completed without complication. There was residual 9° coronal deformity, 2.9 cm left coronal imbalance, and 2.3 cm sagittal imbalance. He had a marked improvement in his function, as assessed by the SF-36 physical component score (pre-op 31.1; post-op 44.7) and mental component score (pre-op 46.0; post-op 66.8). Post-operatively, neck disability index scores also improved (pre-op 38; post-op 16). Although the patient passed away from a drug overdose 14 months post-operatively, he did not report neck pain, he had not sought evaluation from another physician for his neck, and he had not undergone a subsequent neck operation before his passing. In this one patient, an asymmetric C7 PSO was performed safely. While it was effective in addressing a fixed cervical coronal imbalance, its efficacy and safety profile should be confirmed in larger cohorts.

Interchange Reconnection and Coronal Hole Dynamics

NASA Technical Reports Server (NTRS)

Edmondson, J. K.; Antiochos, S. K.; DeVore, C. R.; Lynch, B. J.; Zurbuchen, T. H.

2011-01-01

We investigate the effect of magnetic reconnection between open and closed field, (often referred to as "interchange" reconnection), on the dynamics and topology of coronal hole boundaries. The most important and most prevalent 3D topology of the interchange process is that of a small-scale bipolar magnetic field interacting with a large-scale background field. We determine the evolution of such a magnetic topology by numerical solution of the fully 3D MHD equations in spherical coordinates. First, we calculate the evolution of a small-scale bipole that initially is completely inside an open field region and then is driven across a coronal hole boundary by photospheric motions. Next the reverse situation is calculated in which the bipole is initially inside the closed region and driven toward the coronal hole boundary. In both cases we find that the stress imparted by the photospheric motions results in deformation of the separatrix surface between the closed field of the bipole and the background field, leading to rapid current sheet formation and to efficient reconnection. When the bipole is inside the open field region, the reconnection is of the interchange type in that it exchanges open and closed field. We examine, in detail, the topology of the field as the bipole moves across the coronal hole boundary, and find that the field remains well-connected throughout this process. Our results imply that open flux cannot penetrate deeply into the closed field region below a helmet streamer and, hence, support the quasi-steady models in which open and closed flux remain topologically distinct. Our results also support the uniqueness hypothesis for open field regions as postulated by Antiochos et al. We discuss the implications of this work for coronal observations. Subject Headings: Sun: corona Sun: magnetic fields Sun: reconnection Sun: coronal hole

First 2017-total-eclipse results from the Williams College team

NASA Astrophysics Data System (ADS)

Pasachoff, J.; Dantowitz, R.; Rusin, V.; Seiradakis, J. H.; Voulgaris, A.; Seaton, D. B.; Davis, A. B.; Lu, M.; Sliski, D.; Ladd, E. F.; Economou, T.; Peñaloza-Murillo, M. A.; Nagle-McNaughton, T.

2017-12-01

We report on a wide range of observations we carried out during the total solar eclipse of August 21, 2017. Our main site was on the campus of Willamette University, Salem, Oregon, at which we had a variety of telescopes, spectrographs, cameras, a grism, and terrestrial-atmospheric measuring devices. Our goals included differentiating between models of coronal heating through measuring power-spectra of coronal loops in the [Fe XIV] and [Fe X] emission lines at multi-Hertz cadence with a frame-transfer CCD and otherwise; following coronal structure over the solar-activity cycle; comparing the results of a full-MHD prediction with actual coronal streamers; studying the dynamics of coronal plumes given the minimum phase of the solar-activity cycle; measuring the variation of the corona over the solar-activity cycle from our continuing measurements of the green-line/red-line intensity ratio; studying a variety of additional coronal emisson lines; high-resolution coronal imaging compared with overlapping images from space coronagraphs aboard SoHO and STEREO; comparing with AIA/SDO, HMO/SDO, SUVI/GOES-16, and SWAP/PROBA2 space images; and more. Our research has been supported in large part by grants from the Committee for Research and Exploration of the National Geographic Society and from the Solar Terrestrial Program of the Atmospheric and Geospace Sciences Division of the National Science Foundation, with additional support from Sigma Xi. Additional support for undergraduate participation came from the NSF, the NASA Massachusetts Space Grant Consortium, and the Clare Booth Luce Foundation, with travel support from the Freeman Foote Fund, the Rob Spring Fund, the Brandi Fund, and other sources at Williams College.

Can Polar Fields Explain Missing Open Flux?

NASA Astrophysics Data System (ADS)

Linker, J.; Downs, C.; Caplan, R. M.; Riley, P.; Mikic, Z.; Lionello, R.

2017-12-01

The "open" magnetic field is the portion of the Sun's magnetic field that extends out into the heliosphere and becomes the interplanetary magnetic field (IMF). Both the IMF and the Sun's magnetic field in the photosphere have been measured for many years. In the standard paradigm of coronal structure, the open magnetic field originates primarily in coronal holes. The regions that are magnetically closed trap the coronal plasma and give rise to the streamer belt. This basic picture is qualitatively reproduced by models of coronal structure using photospheric magnetic fields as input. If this paradigm is correct, there are two primary observational constraints on the models: (1) The open field regions in the model should approximately correspond to coronal holes observed in emission, and (2) the magnitude of the open magnetic flux in the model should match that inferred from in situ spacecraft measurements. Linker et al. (2017, ApJ, submitted) investigated the July 2010 time period for a range of observatory maps and both PFSS and MHD models. We found that all of the model/map combinations underestimated the interplanetary magnetic flux, unless the modeled open field regions were larger than observed coronal holes. An estimate of the open magnetic flux made entirely from solar observations (combining detected coronal hole boundaries with observatory synoptic magnetic maps) also underestimated the interplanetary magnetic flux. The magnetic field near the Sun's poles is poorly observed and may not be well represented in observatory maps. In this paper, we explore whether an underestimate of the polar magnetic flux during this time period could account for the overall underestimate of open magnetic flux. Research supported by NASA, AFOSR, and NSF.

Apical root canal microbiota as determined by reverse-capture checkerboard analysis of cryogenically ground root samples from teeth with apical periodontitis.

PubMed

Rôças, Isabela N; Alves, Flávio R F; Santos, Adriana L; Rosado, Alexandre S; Siqueira, José F

2010-10-01

Bacteria located in the apical root canal system potentially participate in the pathogenesis of apical periodontitis. Detection and identification of apical bacteria can be compromised because of limitations in conventional sampling and identification procedures. This study identified several bacterial taxa in the apical and middle/coronal segments of primarily infected root canal system by using pulverized root segments and a culture-independent molecular method. Seventeen extracted teeth with attached apical periodontitis lesions were sectioned to obtain 2 root fragments (apical and middle/coronal segments). Root fragments were cryogenically ground, and DNA was extracted from samples. After multiple displacement amplification, DNA from samples was used as template in a reverse-capture checkerboard hybridization assay targeting 28 bacterial taxa. Bacterial DNA was detected in all samples. The most prevalent taxa in the apical root canal system were Olsenella uli (76.5%), Prevotella baroniae (71%), Porphyromonas endodontalis (65%), Fusobacterium nucleatum (53%), and Tannerella forsythia (47%). O. uli, P. endodontalis, and Propionibacterium acnes were as frequently detected in apical samples as they were in middle/coronal samples. P. baroniae, T. forsythia, and F. nucleatum were found more frequently in the apical part of the canal as compared with matched coronal segments. Streptococcus species were more prevalent in middle/coronal samples. The median and mean of shared bacterial taxa between matched apical and middle/coronal segments were 27% and 41%, respectively. Several candidate endodontic pathogens were very prevalent in the apical root canal system. The apical microbiota was usually complex and differed in species composition when compared with the microbiota of middle/coronal samples from the same tooth. Copyright © 2010 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Simulating the Coronal Evolution of AR 11437 Using SDO/HMI Magnetograms

NASA Astrophysics Data System (ADS)

Yardley, Stephanie L.; Mackay, Duncan H.; Green, Lucie M.

2018-01-01

The coronal magnetic field evolution of AR 11437 is simulated by applying the magnetofrictional relaxation technique of Mackay et al. A sequence of photospheric line-of-sight magnetograms produced by the Solar Dynamics Observatory (SDO)/Helioseismic Magnetic Imager (HMI) is used to drive the simulation and continuously evolve the coronal magnetic field of the active region through a series of nonlinear force-free equilibria. The simulation is started during the first stages of the active region emergence so that its full evolution from emergence to decay can be simulated. A comparison of the simulation results with SDO/Atmospheric Imaging Assembly (AIA) observations show that many aspects of the active region’s observed coronal evolution are reproduced. In particular, it shows the presence of a flux rope, which forms at the same location as sheared coronal loops in the observations. The observations show that eruptions occurred on 2012 March 17 at 05:09 UT and 10:45 UT and on 2012 March 20 at 14:31 UT. The simulation reproduces the first and third eruption, with the simulated flux rope erupting roughly 1 and 10 hr before the observed ejections, respectively. A parameter study is conducted where the boundary and initial conditions are varied along with the physical effects of Ohmic diffusion, hyperdiffusion, and an additional injection of helicity. When comparing the simulations, the evolution of the magnetic field, free magnetic energy, relative helicity and flux rope eruption timings do not change significantly. This indicates that the key element in reproducing the coronal evolution of AR 11437 is the use of line-of-sight magnetograms to drive the evolution of the coronal magnetic field.

The angle of inclination of the native ACL in the coronal and sagittal planes.

PubMed

Reid, Jonathan C; Yonke, Bret; Tompkins, Marc

2017-04-01

The purpose of this cross-sectional study was to evaluate the angle of inclination of the native anterior cruciate ligament (ACL) in both the sagittal and coronal planes and to evaluate these findings based on sex, height, BMI, and skeletal maturity. Inclusion criteria for the study included patients undergoing routine magnetic resonance imaging (MRI) of the knee at a single outpatient orthopedic center who had an intact ACL on MRI. Measurements of the angle of inclination were made on MRIs in both the sagittal and coronal planes. Patients were compared based on sex, height, BMI, and skeletal maturity. One-hundred and eighty-eight patients were included (36 skeletally immature/152 skeletally mature; 98 male/90 female). The overall angle of inclination was 74.3° ± 4.8° in the coronal plane and 46.9° ± 4.9° in the sagittal plane. Skeletally immature patients (coronal: 71.8° ± 6.1°; sagittal: 44.7° ± 5.5°) were significantly different in both coronal and sagittal planes (P = 0.04 and 0.01, respectively) from skeletally mature patients (coronal: 75.3° ± 4.7°; sagittal: 47.4° ± 4.7°). There were no differences based on sex, height, or BMI. There are differences between the angle of inclination findings in this study and other studies, which could be due to MRI and measurement techniques. Clinically, skeletal maturity may be important to account for when using the ACL angle of inclination to evaluate anatomic ACL reconstruction. Prognostic retrospective study, Level of evidence III.

The wide skirt of the bashful ballerina: Hemispheric asymmetry of the heliospheric magnetic field in the inner and outer heliosphere

NASA Astrophysics Data System (ADS)

Mursula, K.; Virtanen, I.

2012-04-01

We reanalyze the observations of the heliospheric magnetic field (HMF) made by the Pioneer 10 and 11 and Voyager 1 and 2 heliospheric probes since 1972, and calculate the HMF sector occurrence ratios and tangential component strengths in the different regions of the heliosphere. Observations at the distant probes and at 1 AU show a very consistent picture of the HMF sector structure in the entire heliosphere, and even beyond the termination shock. Pioneer 11 and Voyager 1 show that the development of northern polar coronal holes was very systematic and active during all the four solar minima since mid-1970s. On the other hand, Voyager 2 observations show a less systematic and delayed development of southern coronal holes in 1980s, 1990s and 2000s. This delay in the evolution of southern coronal holes with respect to the rapid and systematic evolution of northern coronal holes leads to a larger extent of northern coronal holes and a southward shift of the heliospheric current sheet (the bashful ballerina phenomenon) for a few years in the late declining phase of each solar cycle. HMF observations of the probes also directly verify the HCS southward shift, supporting earlier observations at 1-2 AU by the Ulysses probe and Earth-orbiting satellites and extending them into the more distant heliosphere. Although the evidence for the connection between the temporal difference in the evolution of polar coronal holes and the bashful ballerina times is based only on three solar cycles, this may be a common pattern for solar coronal hole evolution since the southward shift of the HCS has occurred at least since solar cycle 16.

The wide skirt of the bashful ballerina: Hemispheric asymmetry of the heliospheric magnetic field in the inner and outer heliosphere

NASA Astrophysics Data System (ADS)

Mursula, K.; Virtanen, I. I.

2012-08-01

We reanalyze the observations of the heliospheric magnetic field (HMF) made by the Pioneer 10 and 11 and Voyager 1 and 2 heliospheric probes since 1972, and calculate the HMF sector occurrence ratios and tangential component strengths in the different regions of the heliosphere. Observations at the distant probes and at 1 AU show a very consistent picture of the HMF sector structure in the entire heliosphere, and even beyond the termination shock. HMF observations by the probes also support the southward shift of the heliospheric current sheet (the bashful ballerina phenomenon), which is observed earlier at 1-2 AU by the Ulysses probe and Earth-orbiting satellites, and verify the HCS shift over a wide range of radial distances until the distant heliosphere. Pioneer 11 and Voyager 1 show that the development of northern polar coronal holes was very systematic and active during all the four solar minima since mid-1970s, while Voyager 2 observations show a less systematic and delayed development of southern coronal holes in 1980s, 1990s and 2000s. This delay in the evolution of southern coronal holes with respect to the rapid and systematic evolution of northern coronal holes leads to a larger extent of northern coronal holes and the southward shift of the HCS for a few years in the late declining phase of each solar cycle. Although evidence for the connection between the different evolution of polar coronal holes and the bashful ballerina phenomenon is obtained here only for three solar cycles, this may be a common pattern for solar coronal hole evolution since the southward shift of the HCS has occurred at least since solar cycle 16.

PHYSICAL CONDITIONS OF CORONAL PLASMA AT THE TRANSIT OF A SHOCK DRIVEN BY A CORONAL MASS EJECTION

DOE Office of Scientific and Technical Information (OSTI.GOV)

Susino, R.; Bemporad, A.; Mancuso, S., E-mail: susino@oato.inaf.it

2015-10-20

We report here on the determination of plasma physical parameters across a shock driven by a coronal mass ejection using white light (WL) coronagraphic images and radio dynamic spectra (RDS). The event analyzed here is the spectacular eruption that occurred on 2011 June 7, a fast CME followed by the ejection of columns of chromospheric plasma, part of them falling back to the solar surface, associated with a M2.5 flare and a type-II radio burst. Images acquired by the Solar and Heliospheric Observatory/LASCO coronagraphs (C2 and C3) were employed to track the CME-driven shock in the corona between 2–12 R{submore » ⊙} in an angular interval of about 110°. In this interval we derived two-dimensional (2D) maps of electron density, shock velocity, and shock compression ratio, and we measured the shock inclination angle with respect to the radial direction. Under plausible assumptions, these quantities were used to infer 2D maps of shock Mach number M{sub A} and strength of coronal magnetic fields at the shock's heights. We found that in the early phases (2–4 R{sub ⊙}) the whole shock surface is super-Alfvénic, while later on (i.e., higher up) it becomes super-Alfvénic only at the nose. This is in agreement with the location for the source of the observed type-II burst, as inferred from RDS combined with the shock kinematic and coronal densities derived from WL. For the first time, a coronal shock is used to derive a 2D map of the coronal magnetic field strength over intervals of 10 R{sub ⊙} altitude and ∼110° latitude.« less

Investigating Town Design and Social Organization at Port Tobacco, Maryland Through the Use of Archaeology and Geophysics

NASA Astrophysics Data System (ADS)

Quantock, Peter C.

This thesis examines the connection between town planning and social organization at the small town site of Port Tobacco in south-central Charles County, Maryland from the beginning of the 18th century through to the end of the 19th century. By employing a methodology of both geophysical techniques and archaeological excavations, I was able to locate and map numerous structures and features associated with town planning and examine how these spaces were used. This data was used to show how social order, power, and wealth transformed the town layout from a linear settlement along the river into a grid-like pattern. Specifically, I was able to show that these changes in town layout were dominated by the power of the local elite landowners and tobacco merchants.

Three Coronal Holes

NASA Image and Video Library

2018-04-16

For much of this week the sun featured three substantial coronal holes (Apr. 3-6, 2018). Coronal holes appear as large dark areas which are identified with arrows in the still image. These are areas of open magnetic field from which high speed solar wind rushes out into space. This wind, if it interacts with Earth's magnetosphere, can cause aurora to appear near the poles. They are not at all uncommon. Animations are available at https://photojournal.jpl.nasa.gov/catalog/PIA22414

ATM observations - X-ray results. [solar coronal structure from Skylab experiments

NASA Technical Reports Server (NTRS)

Vaiana, G. S.; Zombeck, M.; Krieger, A. S.; Timothy, A. F.

1976-01-01

Preliminary results of the solar X-ray observations from Skylab are reviewed which indicate a highly structured nature for the corona, with closed magnetic-loop structures over a wide range of size scales. A description of the S-054 experiments is provided, and values are given for the parameters - including size, density, and temperature - describing a variety of typical coronal features. The structure and evolution of active regions, coronal holes, and bright points are discussed.

Energy conversion in the coronal plasma

NASA Technical Reports Server (NTRS)

Martens, P. C. H.

1986-01-01

Solar and stellar X-ray emission are the observed waste products of the interplay between magnetic fields and the motion of stellar plasma. Theoretical understanding of the process of coronal heating is of utmost importance, since the high temperature is what defines the corona in the first place. Most of the research described deals with the aspects of the several rivalling theories for coronal heating. The rest of the papers deal with processes of energy conversion related to flares.

Coronal propagation of flare associated electrons and protons

NASA Technical Reports Server (NTRS)

Schellert, G.; Wibberenz, G.; Kunow, H.

1985-01-01

A statistical study of characteristic times and intensities of 36 solar particle events observed between 1977 and 1979 by the Kiel Cosmic Ray Experiment on board HELIOS-1 and -2 has been carried out. For approx. 0.5 MeV electrons we order the times of maximum and the absolute intensities with respect to angular distance from the parent flare. Discussion of coronal parameters in terms of Reid's model leads to typical time constants for coronal diffusion and escape.

Ecology of the microbiome of the infected root canal system: a comparison between apical and coronal root segments

PubMed Central

Özok, A.R.; Persoon, I.F.; Huse, S.M.; Keijser, B.J.F.; Wesselink, P.R.; Crielaard, W.; Zaura, E.

2016-01-01

Aim To evaluate the microbial ecology of the coronal and apical segments of infected root canal systems using a complete sampling technique and next-generation sequencing. Methodology The roots of 23 extracted teeth with apical periodontitis were sectioned in half, horizontally, and cryo-pulverized. Bacterial communities were profiled using tagged 454 pyrosequencing of the 16S rDNA hypervariable V5–V6 region. Results The sequences were classified into 606 taxa (species or higher taxon), representing 24 bacterial phyla or candidate divisions and one archaeal phylum. Proteobacteria were more abundant in the apical samples (p<0.05), while Actinobacteria were in significantly higher proportions in the coronal samples. The apical samples harbored statistically significantly more taxa than the coronal samples (p=0.01), and showed a higher microbial diversity. Several taxa belonging to fastidious obligate anaerobes were significantly more abundant in the apical segments of the roots compared to their coronal counterparts. Conclusions Endodontic infections are more complex than reported previously. The apical part of the root canal system drives the selection of a more diverse and more anaerobe community than the coronal part. The presence of a distinct ecological niche in the apical region explains the difficulty of eradication of the infection, and emphasizes the need that new treatment approaches should be developed. PMID:22251411

Image-based reconstruction of the Newtonian dynamics of solar coronal ejecta

NASA Astrophysics Data System (ADS)

Uritsky, Vadim M.; Thompson, Barbara J.

2016-10-01

We present a new methodology for analyzing rising and falling dynamics of unstable coronal material as represented by high-cadence SDO AIA images. The technique involves an adaptive spatiotemporal tracking of propagating intensity gradients and their characterization in terms of time-evolving areas swept out by the position vector originated from the Sun disk center. The measured values of the areal velocity and acceleration are used to obtain quantitative information on the angular momentum and acceleration along the paths of the rising and falling coronal plasma. In the absence of other forces, solar gravitation results in purely ballistic motions consistent with the Kepler's second law; non-central forces such as the Lorentz force introduce non-zero torques resulting in more complex motions. The developed algorithms enable direct evaluation of the line-of-sight component of the net torque applied to a unit mass of the ejected coronal material which is proportional to the image-plane projection of the observed areal acceleration. The current implementation of the method cannot reliably distinguish torque modulations caused by the coronal force field from those imposed by abrupt changes of plasma mass density and nontrivial projection effects. However, it can provide valid observational constraints on the evolution of large-scale unstable magnetic topologies driving major solar-coronal eruptions as demonstrated in the related talk by B. Thompson et al.

Assessment of the amount of remaining coronal dentine in root-treated teeth.

PubMed

Bandlish, R B; McDonald, A V; Setchell, D J

2006-10-01

There is currently no standardised technique to measure the amount of coronal dentine remaining in a root-treated tooth after crown preparation. The aim of this study was to develop a method of measuring remaining coronal dentine in root-treated teeth and to propose an index for grading tooth restorability. The study recruited 20 patients who had completed molar endodontic treatment at the Eastman Dental Hospital and had been prescribed an amalgam coronal-radicular core with a full coverage cast restoration. Using a series of interlocking special trays and impressions, a method was devised to produce a cast of the amount of remaining dentine coronal to the finish line after crown preparation. This cast was scanned using a laser profilometer and the volume of remaining dentine was calculated. A tooth restorability index (TRI) was developed to assess the strategic value of the remaining dentine. The TRI allowed scores of 0-3 in each sextant with a maximum score of 18 per tooth. Twenty teeth were scored by three examiners and the TRI scores varied from 2 to 13. The volume of coronal dentine varied from 61.73 to 232.22 mm(3). A tooth restorability index has been devised to assess the strategic value of remaining dentine. A Kappa statistic was calculated to produce values of 0.584, 0.688 and 0.720, giving moderate-good agreement between the examiners.

THE CONTRACTION OF OVERLYING CORONAL LOOP AND THE ROTATING MOTION OF A SIGMOID FILAMENT DURING ITS ERUPTION

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yan, X. L.; Qu, Z. Q.; Xue, Z. K.

We present an observation of overlying coronal loop contraction and rotating motion of the sigmoid filament during its eruption on 2012 May 22 observed by the Solar Dynamics Observatory (SDO). Our results show that the twist can be transported into the filament from the lower atmosphere to the higher atmosphere. The successive contraction of the coronal loops was due to a suddenly reduced magnetic pressure underneath the filament, which was caused by the rising of the filament. Before the sigmoid filament eruption, there was a counterclockwise flow in the photosphere at the right feet of the filament and the contractionmore » loops and a convergence flow at the left foot of the filament. The hot and cool materials have inverse motion along the filament before the filament eruption. Moreover, two coronal loops overlying the filament first experienced brightening, expansion, and contraction successively. At the beginning of the rising and rotation of the left part of the filament, the second coronal loop exhibited rapid contraction. The top of the second coronal loop also showed counterclockwise rotation during the contraction process. After the contraction of the second loop, the left part of the filament rotated counterclockwise and expanded toward the right of NOAA AR 11485. During the filament expansion, the right part of the filament also exhibited counterclockwise rotation like a tornado.« less

The Contraction of Overlying Coronal Loop and the Rotating Motion of a Sigmoid Filament during Its Eruption

NASA Astrophysics Data System (ADS)

Yan, X. L.; Pan, G. M.; Liu, J. H.; Qu, Z. Q.; Xue, Z. K.; Deng, L. H.; Ma, L.; Kong, D. F.

2013-06-01

We present an observation of overlying coronal loop contraction and rotating motion of the sigmoid filament during its eruption on 2012 May 22 observed by the Solar Dynamics Observatory (SDO). Our results show that the twist can be transported into the filament from the lower atmosphere to the higher atmosphere. The successive contraction of the coronal loops was due to a suddenly reduced magnetic pressure underneath the filament, which was caused by the rising of the filament. Before the sigmoid filament eruption, there was a counterclockwise flow in the photosphere at the right feet of the filament and the contraction loops and a convergence flow at the left foot of the filament. The hot and cool materials have inverse motion along the filament before the filament eruption. Moreover, two coronal loops overlying the filament first experienced brightening, expansion, and contraction successively. At the beginning of the rising and rotation of the left part of the filament, the second coronal loop exhibited rapid contraction. The top of the second coronal loop also showed counterclockwise rotation during the contraction process. After the contraction of the second loop, the left part of the filament rotated counterclockwise and expanded toward the right of NOAA AR 11485. During the filament expansion, the right part of the filament also exhibited counterclockwise rotation like a tornado.

Evidence for the Magnetic Breakout Model in an Equatorial Coronal-hole Jet

NASA Astrophysics Data System (ADS)

Kumar, Pankaj; Karpen, Judith T.; Antiochos, Spiro K.; Wyper, Peter F.; DeVore, C. Richard; DeForest, Craig E.

2018-02-01

Small, impulsive jets commonly occur throughout the solar corona, but are especially visible in coronal holes. Evidence is mounting that jets are part of a continuum of eruptions that extends to much larger coronal mass ejections and eruptive flares. Because coronal-hole jets originate in relatively simple magnetic structures, they offer an ideal testbed for theories of energy buildup and release in the full range of solar eruptions. We analyzed an equatorial coronal-hole jet observed by the Solar Dynamics Observatory (SDO)/AIA on 2014 January 9 in which the magnetic-field structure was consistent with the embedded-bipole topology that we identified and modeled previously as an origin of coronal jets. In addition, this event contained a mini-filament, which led to important insights into the energy storage and release mechanisms. SDO/HMI magnetograms revealed footpoint motions in the primary minority-polarity region at the eruption site, but show negligible flux emergence or cancellation for at least 16 hr before the eruption. Therefore, the free energy powering this jet probably came from magnetic shear concentrated at the polarity inversion line within the embedded bipole. We find that the observed activity sequence and its interpretation closely match the predictions of the breakout jet model, strongly supporting the hypothesis that the breakout model can explain solar eruptions on a wide range of scales.

The Large-scale Coronal Structure of the 2017 August 21 Great American Eclipse: An Assessment of Solar Surface Flux Transport Model Enabled Predictions and Observations

NASA Astrophysics Data System (ADS)

Nandy, Dibyendu; Bhowmik, Prantika; Yeates, Anthony R.; Panda, Suman; Tarafder, Rajashik; Dash, Soumyaranjan

2018-01-01

On 2017 August 21, a total solar eclipse swept across the contiguous United States, providing excellent opportunities for diagnostics of the Sun’s corona. The Sun’s coronal structure is notoriously difficult to observe except during solar eclipses; thus, theoretical models must be relied upon for inferring the underlying magnetic structure of the Sun’s outer atmosphere. These models are necessary for understanding the role of magnetic fields in the heating of the corona to a million degrees and the generation of severe space weather. Here we present a methodology for predicting the structure of the coronal field based on model forward runs of a solar surface flux transport model, whose predicted surface field is utilized to extrapolate future coronal magnetic field structures. This prescription was applied to the 2017 August 21 solar eclipse. A post-eclipse analysis shows good agreement between model simulated and observed coronal structures and their locations on the limb. We demonstrate that slow changes in the Sun’s surface magnetic field distribution driven by long-term flux emergence and its evolution governs large-scale coronal structures with a (plausibly cycle-phase dependent) dynamical memory timescale on the order of a few solar rotations, opening up the possibility for large-scale, global corona predictions at least a month in advance.

Evidence for the Magnetic Breakout Model in an Equatorial Coronal-Hole Jet

NASA Technical Reports Server (NTRS)

Kumar, Pankaj; Karpen, Judith T.; Antiochos, Spiro K.; Wyper, Peter F.; Devore, C. Richard; DeForest, Craig E.

2018-01-01

Small, impulsive jets commonly occur throughout the solar corona, but are especially visible in coronal holes. Evidence is mounting that jets are part of a continuum of eruptions that extends to much larger coronal mass ejections and eruptive flares. Because coronal-hole jets originate in relatively simple magnetic structures, they offer an ideal testbed for theories of energy buildup and release in the full range of solar eruptions. We analyzed an equatorial coronal-hole jet observed by the Solar Dynamics Observatory (SDO)/AIA (Atmospheric Imaging Assembly)) on 2014 January 9 in which the magnetic-field structure was consistent with the embedded-bipole topology that we identified and modeled previously as an origin of coronal jets. In addition, this event contained a mini-filament, which led to important insights into the energy storage and release mechanisms. SDO/HMI (Solar Dynamics Observatory/Helioseismic and Magnetic Imager) magnetograms revealed footpoint motions in the primary minority-polarity region at the eruption site, but show negligible flux emergence or cancellation for at least 16 hours before the eruption. Therefore, the free energy powering this jet probably came from magnetic shear concentrated at the polarity inversion line within the embedded bipole. We find that the observed activity sequence and its interpretation closely match the predictions of the breakout jet model, strongly supporting the hypothesis that the breakout model can explain solar eruptions on a wide range of scales.

Ponderomotive Acceleration in Coronal Loops

NASA Astrophysics Data System (ADS)

Dahlburg, Russell B.; Laming, J. Martin; Taylor, Brian; Obenschain, Keith

2017-08-01

Ponderomotive acceleration has been asserted to be a cause of the First Ionization Potential (FIP) effect, the by now well known enhancement in abundance by a factor of 3-4 over photospheric values of elements in the solar corona with FIP less than about 10 eV. It is shown here by means of numerical simulations that ponderomotive acceleration occurs in solar coronal loops, with the appropriate magnitude and direction, as a ``byproduct'' of coronal heating. The numerical simulations are performed with the HYPERION code, which solves the fully compressible three-dimensional magnetohydrodynamic equations including nonlinear thermal conduction and optically thin radiation. Numerical simulations of a coronal loops with an axial magnetic field from 0.005 Teslas to 0.02 Teslas and lengths from 25000 km to 75000 km are presented. In the simulations the footpoints of the axial loop magnetic field are convected by random, large-scale motions. There is a continuous formation and dissipation of field-aligned current sheets which act to heat the loop. As a consequence of coronal magnetic reconnection, small scale, high speed jets form. The familiar vortex quadrupoles form at reconnection sites. Between the magnetic footpoints and the corona the reconnection flow merges with the boundary flow. It is in this region that the ponderomotive acceleration occurs. Mirroring the character of the coronal reconnection, the ponderomotive acceleration is also found to be intermittent.

A New Infrared Desert Dust Index over French Guyana Rain forest: First results

NASA Astrophysics Data System (ADS)

Molinie, J.; Barnacin, E.; Henry, J. L.; Gobinddass, M. L.; Panechou-Pulcherie, K.; Feuillard, T.; Nagau, J.

2017-12-01

Recently a NASA researcher showed the role of desert dust contribution for the Amazonian rain forest. In another hand, desert dust impact population health when PM 10 level reached values around and upper the PM 10 threshold of the 50 µg m-3, established by the World Health Organization (WHO). Infrared Desert Dust Index (IDDI) developed by Legrand with Meteosat infrared images, allow the following of desert dust plumes over semi-arid land. In French Guiana the WHO threshold is currently overpass in measurements done by ORA air quality network, in the two main towns located close to the coast. For inland population, it is very difficult to have continuous dust measures due to the low infrastructure supplies. We need to develop a tools in order to follow the crossing of desert dust over the French Guyana rain forest, from the coast to inland villages. Following the IDDI concept and comparing with VIIRS AOT EDR result over the same area, a modified IDDI for Amazonian region (IDDI_A) has been proposed to identify the dusty pixels over the forest. Despite of high cloud presence, a good correlation between AOT EDR and IDDI_A was obtained. The IDDI_A calculation has been applied over French Guiana area for different PM 10 level at Cayenne, a town along the coast.

Measuring the scale of sustainability of new town development based on the assessment of the residents of the native settlement around the new town area of Gading Serpong Tangerang

NASA Astrophysics Data System (ADS)

Ischak, M.; Setioko, B.; Nurgandarum, D.

2018-01-01

The growth trend of Jakarta city as a Metropolitan city nowadays is the construction of large-scale planned settlement that is often referred to as a new town and is carried out by major developers. The process of land tenure and the process of constructing the new town are directly tangent to the original pre-existing settlements and shape the pattern or types of original settlements in the context of their relationship with the new town. This research was intended to measure the scale of sustainability due to land expansion by new town developers and was measured from the side of the original settlers who still exist. The research method used was descriptive explorative that is by formulating sustainability criteria that match best with research context and using the criteria as a tool to measure the sustainability level of new city development at research site that is new town of Gading Serpong Tangerang. The research concludes that despite the apparent displacement and restriction of original settlement’ lands, it indicates, overall, that new town development meets sustainability criteria when viewed from the residents of three types of the original settlements.

The effect of glenoid cavity depth on rotator cuff tendinitis.

PubMed

Malkoc, Melih; Korkmaz, Ozgur; Ormeci, Tugrul; Sever, Cem; Kara, Adna; Mahirogulları, Mahir

2016-03-01

Some of the most important causes of shoulder pain are inflammation and degenerative changes in the rotator cuff (RC). Magnetic resonance imaging (MRI) is a noninvasive and safe imaging modality. MRI can be used for the evaluation of cuff tendinopathy. In this study, we evaluated the relationship between glenoid cavity depth and cuff tendinopathy and we investigated glenoid cavity depth on the pathogenesis of cuff tendinopathy. We retrospectively evaluated 215 patients who underwent MRI. Of these, 60 patients showed cuff tendinopathy (group A) and 54 patients showed no pathology (group B). Glenoid cavity depth was calculated in the coronal and transverse planes. The mean axial depth was 1.7 ± 0.9 and the mean coronal depth 3.8 ± 0.9, for group A. The mean axial depth was 3.5 ± 0.7 and the mean coronal depth 1.5 ± 0.8, for group B. There were significant differences in the axial and coronal depths between the two groups. High coronal and low axial depth of the glenoid cavity can be used to diagnose RC tendinitis.

Comparison of apical and coronal extrusions using reciprocating and rotary instrumentation systems.

PubMed

Lu, Yan; Chen, Min; Qiao, Feng; Wu, Ligeng

2015-08-07

The aim of this study was to compare the apical and coronal extrusions by using two reciprocating and two rotary instrumentation systems. Eighty extracted human single-rooted anterior teeth were randomly assigned to four groups. Four different root canal instrumentation systems were used according to the manufacturers instructions, including two reciprocating single-file systems, Reciproc and WaveOne, and two full-sequence rotary BLX and ProTaper instruments. Debris collected from the coronal by the instruments and apical extrusions were quantified respectively. After drying the collections, the mean weight of debris collected from apical and coronal extrusions was assessed using an electronic balance and analyzed using the Kruskal-Wallis H and Mann-Whitney U tests. Statistically significant differences in the apical extrusion were observed among the four groups. Reciproc and WaveOne instruments produced significantly less debris than BLX and ProTaper instruments (P < 0.05). All of the systems produced apical extrusion of debris. However, reciprocating single-file systems produced less apical extrusion than full-sequence rotary systems. No relationship was observed between apical and coronal extrusions.

Coronal Heating by Magnetic Explosions

NASA Technical Reports Server (NTRS)

Moore, Ronald L.; Falconer, D. A.; Porter, Jason G.; Suess, Steven T.

1998-01-01

We build a case for the persistent strong coronal heating in active regions and the pervasive quasi-steady heating of the corona in quiet regions and coronal holes being driven in basically the same way as the intense transient heating in solar flares: by explosions of sheared magnetic fields in the cores of initially closed bipoles. We begin by summarizing the observational case for exploding sheared core fields being the drivers of a wide variety of flare events, with and without coronal mass ejections. We conclude that the arrangement of an event's flare heating, whether there is a coronal mass ejection, and the time and place of the ejection relative to the flare heating are all largely determined by four elements of the form and action the magnetic field: (1) the arrangement of the impacted, interacting bipoles participating in the event, (2) which of these bipoles are active (have sheared core fields that explode) and which are passive (are heated by injection from impacted active bipoles), (3) which core field explodes first, and (4) which core-field explosions are confined within the closed field of their bipoles and which ejectively open their bipoles.

Study of the solar coronal hole rotation

NASA Astrophysics Data System (ADS)

Oghrapishvili, N. B.; Bagashvili, S. R.; Maghradze, D. A.; Gachechiladze, T. Z.; Japaridze, D. R.; Shergelashvili, B. M.; Mdzinarishvili, T. G.; Chargeishvili, B. B.

2018-06-01

Rotation of coronal holes is studied using data from SDO/AIA for 2014 and 2015. A new approach to the treatment of data is applied. Instead of calculated average angular velocities of each coronal hole centroid and then grouping them in latitudinal bins for calculating average rotation rates of corresponding latitudes, we compiled instant rotation rates of centroids and their corresponding heliographic coordinates in one matrix for further processing. Even unfiltered data showed clear differential nature of rotation of coronal holes. We studied possible reasons for distortion of data by the limb effects to eliminate some discrepancies at high latitudes caused by the high order of scattering of data in that region. A study of the longitudinal distribution of angular velocities revealed the optimal longitudinal interval for the best result. We examined different methods of data filtering and realized that filtration using targeting on the local medians of data with a constant threshold is a more acceptable approach that is not biased towards a predefined notion of an expected result. The results showed a differential pattern of rotation of coronal holes.

Polarimetry of the HI Lyman-alpha for coronal magnetic field diagnostics

NASA Technical Reports Server (NTRS)

Fineschi, Silvano; Hoover, Richard B.; Zukic, Muamer; Kim, Jongmin; Walker, Arthur B. C., Jr.; Baker, Phillip, C.

1993-01-01

We discuss and analyze the possible sources of observational and instrumental uncertainty that can be encountered in measuring magnetic fields of the solar corona through polarimetric observations of the Hanle effect of the coronal Ly-alpha line. The Hanle effect is the modification of the linear polarization of a resonantly scattered line, due to the presence of a magnetic field. Simulated observations are used to examine how polarimetric measurements of this effect are affected by the line-of-sight integration, the electron collisions, and the Ly-alpha geocorona. We plan to implement the coronal magnetic field diagnostics via the Ly-alpha Hanle effect using an all-reflecting Ly-alpha coronagraph/polarimeter (Ly-alphaCoPo) which employs reflecting multilayer mirrors, polarizers, and filters. We discuss here the requirements for such an instrument, and analyze the sources of instrumental uncertainty for polarimetric observations of the coronal Ly-alpha Hanle effect. We conclude that the anticipated polarization signal from the corona and the expected performance of the Ly-alphaCoPo instrument are such that the Ly-alpha Hanle effect method for coronal field diagnostics is feasible.

Automated coronal hole identification via multi-thermal intensity segmentation

NASA Astrophysics Data System (ADS)

Garton, Tadhg M.; Gallagher, Peter T.; Murray, Sophie A.

2018-01-01

Coronal holes (CH) are regions of open magnetic fields that appear as dark areas in the solar corona due to their low density and temperature compared to the surrounding quiet corona. To date, accurate identification and segmentation of CHs has been a difficult task due to their comparable intensity to local quiet Sun regions. Current segmentation methods typically rely on the use of single Extreme Ultra-Violet passband and magnetogram images to extract CH information. Here, the coronal hole identification via multi-thermal emission recognition algorithm (CHIMERA) is described, which analyses multi-thermal images from the atmospheric image assembly (AIA) onboard the solar dynamics observatory (SDO) to segment coronal hole boundaries by their intensity ratio across three passbands (171 Å, 193 Å, and 211 Å). The algorithm allows accurate extraction of CH boundaries and many of their properties, such as area, position, latitudinal and longitudinal width, and magnetic polarity of segmented CHs. From these properties, a clear linear relationship was identified between the duration of geomagnetic storms and coronal hole areas. CHIMERA can therefore form the basis of more accurate forecasting of the start and duration of geomagnetic storms.

Mini-filament Eruption as the Initiation of a Jet along Coronal Loops

NASA Astrophysics Data System (ADS)

Hong, Junchao; Jiang, Yunchun; Yang, Jiayan; Yang, Bo; Xu, Zhe; Xiang, Yongyuan

2016-10-01

Minifilament eruptions (MFEs) and coronal jets are different types of solar small-scale explosive events. We report an MFE observed at the New Vacuum Solar Telescope (NVST). As seen in the NVST Hα images, during the rising phase, the minifilament erupts outward orthogonally to its length, accompanied with a flare-like brightening at the bottom. Afterward, dark materials are found to possibly extend along the axis of the expanded filament body. The MFE is analogous to large filament eruptions. However, a simultaneous observation of the Solar Dynamics Observatory shows that a jet is initiated and flows out along nearby coronal loops during the rising phase of the MFE. Meanwhile, small hot loops, which connect the original eruptive site of the minifilament to the footpoints of the coronal loops, are formed successively. A differential emission measure analysis demonstrates that, on the top of the new small loops, a hot cusp structure exists. We conjecture that the magnetic fields of the MFE interact with magnetic fields of the coronal loops. This interaction is interpreted as magnetic reconnection that produces the jet and the small hot loops.

Hong Kong New Town Sustainability Analysis from the Perspective of Low-Carbon Eco-City—Taking Tseung Kwan O New Town as an Example

NASA Astrophysics Data System (ADS)

Liu, Siqi; Huang, Guanqi

2018-01-01

Recent years, people have paid more attentions to environmental issues involving air pollution, urban heat island effect and accessibility of green space. Hong Kong is a representative high-density city. The mission of Hong Kong New Town Development is to scatter the densely urban centre population and to improve living quality. Based on the ArcGIS and CFD scientific simulation, this paper focus on the sustainability analysis of Hong Kong new town from the view of Low-Carbon Eco-City, taking Tseung Kwan O new town as the research object.

Picher, Oklahoma

NASA Image and Video Library

2012-05-30

NASA Terra spacecraft acquired this image of Picher, Oklahoma which once boasted 20,000 people in this mining town in northeast Oklahoma. Now, after a 2009 tornado, and a federal cleanup program, the town is a modern-day ghost town.

Teaching Our Town in Our Town

ERIC Educational Resources Information Center

Haberling, Jennifer A.; White, Brian

2004-01-01

Teachers from a high school and university collaborated to analyze the obstacles students encountered while understanding the theatre play "Our Town". A description on the activities undertaken to help students approach and appreciate the play is presented.

Research in solar plasma theory

NASA Technical Reports Server (NTRS)

Vanhoven, Gerard

1992-01-01

The main thrust and significance of our research results are presented. The topics covered include: (1) coronal structure and dynamics; (2) coronal heating; (3) filament formation; and (4) flare energy release.

Theoretical scaling law of coronal magnetic field and electron power-law index in solar microwave burst sources

NASA Astrophysics Data System (ADS)

Huang, Y.; Song, Q. W.; Tan, B. L.

2018-04-01

It is first proposed a theoretical scaling law respectively for the coronal magnetic field strength B and electron power-law index δ versus frequency and coronal height in solar microwave burst sources. Based on the non-thermal gyro-synchrotron radiation model (Ramaty in Astrophys. J. 158:753, 1969), B and δ are uniquely solved by the observable optically-thin spectral index and turnover (peak) frequency, the other parameters (plasma density, temperature, view angle, low and high energy cutoffs, etc.) are relatively insensitive to the calculations, thus taken as some typical values. Both of B and δ increase with increasing of radio frequency but with decreasing of coronal height above photosphere, and well satisfy a square or cubic logarithmic fitting.

Using Coronal Hole Maps to Constrain MHD Models

NASA Astrophysics Data System (ADS)

Caplan, Ronald M.; Downs, Cooper; Linker, Jon A.; Mikic, Zoran

2017-08-01

In this presentation, we explore the use of coronal hole maps (CHMs) as a constraint for thermodynamic MHD models of the solar corona. Using our EUV2CHM software suite (predsci.com/chd), we construct CHMs from SDO/AIA 193Å and STEREO-A/EUVI 195Å images for multiple Carrington rotations leading up to the August 21st, 2017 total solar eclipse. We then contruct synoptic CHMs from synthetic EUV images generated from global thermodynamic MHD simulations of the corona for each rotation. Comparisons of apparent coronal hole boundaries and estimates of the net open flux are used to benchmark and constrain our MHD model leading up to the eclipse. Specifically, the comparisons are used to find optimal parameterizations of our wave turbulence dissipation (WTD) coronal heating model.

Energy balance of stellar coronae. I - Methods and examples. II - Effect of coronal heating

NASA Technical Reports Server (NTRS)

Hammer, R.

1982-01-01

Simplified models of magnetically open coronal regions are computed, with the aim of fulfilling appropriate boundary conditions at the base of the atmosphere, at the critical point, and at infinity. The models are determined by the stellar mass and radius and by the amount and location of coronal heating, and this dependence is analyzed in terms of pressure, temperature, characteristic heights, energy losses, mass loss, and asymptotic behavior. The results are used to classify the magnetically open coronal regions according to the energy loss mechanism that dominates in the region between the base and the critical point, and it is shown that more complicated heating mechanisms may be replaced by the presented exponential heating law, provided that the damping length is suitably chosen.

Observational Analysis of Coronal Fans

NASA Technical Reports Server (NTRS)

Talpeanu, D.-C.; Rachmeler, L; Mierla, Marilena

2017-01-01

Coronal fans (see Figure 1) are bright observational structures that extend to large distances above the solar surface and can easily be seen in EUV (174 angstrom) above the limb. They have a very long lifetime and can live up to several Carrington rotations (CR), remaining relatively stationary for many months. Note that they are not off-limb manifestation of similarly-named active region fans. The solar conditions required to create coronal fans are not well understood. The goal of this research was to find as many associations as possible of coronal fans with other solar features and to gain a better understanding of these structures. Therefore, we analyzed many fans and created an overview of their properties. We present the results of this statistical analysis and also a case study on the longest living fan.

Coronal Loop Evolution Observed with AIA and Hi-C

NASA Technical Reports Server (NTRS)

Mulu-Moore, Fana; Winebarger, A.; Cirtain, J.; Kobayashi, K.; Korreck, K.; Golub, L.; Kuzin. S.; Walsh, R.; DeForest, C.; DePontieu, B.;

Search for X-ray Emission from AGB Stars in the Coronal Graveyard

NASA Astrophysics Data System (ADS)

Montez, Rodolfo

2013-10-01

Maser observations demonstrate the existence of magnetic fields in the circumstellar envelopes of AGB stars. However, thus far, only 2-3 AGB stars have exhibited evidence for coronal X-ray emission. We have demonstrated that only the sensitivity of modern X-ray telescopes can detect magnetically-induced coronal emission and have identified a sample of AGB stars which are ideal candidates to search for such emission. Specifically, we have selected a sample of AGB stars with SiO maser emission, UV emission in at least one of the GALEX bandpasses, and low mass loss rates. The four selected AGB stars provide a pilot sample that optimally probes for coronal activity beyond the giant phase and that provides valuable tests for the launching and shaping of AGB mass loss.

Radiative transfer of X-rays in the solar corona

NASA Technical Reports Server (NTRS)

Acton, L. W.

1978-01-01

The problem of resonance scattering of X-ray emission lines in the solar corona is investigated. For the resonance lines of some helium-like ions, significant optical depths are reached over distances small compared with the size of typical coronal features. A general integral equation for the transfer of resonance-line radiation under solar coronal conditions is derived. This expression is in a form useful for modeling the complex three-dimensional temperature and density structure of coronal active regions. The transfer equation is then cast in a form illustrating the terms which give rise to the attenuation or enhancement of the resonance-line intensity. The source function for helium-like oxygen (O VII) under coronal conditions is computed and discussed in terms of the relative importance of scattering.

Testing the Accuracy of Data-driven MHD Simulations of Active Region Evolution and Eruption

NASA Astrophysics Data System (ADS)

Leake, J. E.; Linton, M.; Schuck, P. W.

2017-12-01

Models for the evolution of the solar coronal magnetic field are vital for understanding solar activity, yet the best measurements of the magnetic field lie at the photosphere, necessitating the recent development of coronal models which are "data-driven" at the photosphere. Using magnetohydrodynamic simulations of active region formation and our recently created validation framework we investigate the source of errors in data-driven models that use surface measurements of the magnetic field, and derived MHD quantities, to model the coronal magnetic field. The primary sources of errors in these studies are the temporal and spatial resolution of the surface measurements. We will discuss the implications of theses studies for accurately modeling the build up and release of coronal magnetic energy based on photospheric magnetic field observations.

Stereoscopy and Tomography of Coronal Structures

NASA Astrophysics Data System (ADS)

de Patoul, J.

2012-04-01

The hot solar corona consists of a low density plasma, which is highly structured by the magnetic field. To resolve and study the corona, several solar Ultraviolet (UV) and X-ray telescopes are operated with high spatial and temporal resolution. EUV (Extreme UV) image sequences of the lower solar corona have revealed a wide variety of structures with sizes ranging from the Sun's diameter to the limit of the angular resolution. Active regions can be observed with enhanced temperature and density, as well as 'quiet' regions, coronal holes with lower density and numerous other transient phenomena such as plumes, jets, bright points, flares, filaments, coronal mass ejections, all structured by the coronal magnetic field. In this work, we analyze polar plumes in a sequence of Solar EUV images taken nearly simultaneously by the three telescopes on board of the spacecraft STEREO/SECCHI A and B, and SOHO/EIT. Plumes appear in EUV images as elongated objects starting on the surface of the Sun extending super-radially into the corona. Their formation and contribution to the fast solar wind and other coronal phenomena are still under debate. Knowledge of the polar plume 3-D geometry can help to understand some of the physical processes in the solar corona. In this dissertation we develop new techniques for the characterization of polar plume structures in solar coronal images (Part II) then we analyze these structures using the techniques (Part III): We design a new technique capable of automatically identifying plumes in solar EUV images close to the limb at 1.01-1.39 Ro. This plume identification is based on a multi-scale Hough-wavelet analysis. We show that the method is well adapted to identifying the location, width and orientation of plumes. Starting from Hough-wavelet analysis, we elaborate on two other techniques to determine 3-D plume localization and structure: (i) tomography employing data from a single spacecraft over more than half a rotation and (ii) stereoscopy from simultaneous data observed by two or more spacecrafts. For tomography, we consider the filtered back projection method for which we incorporate the differential rotation of the Sun. For stereoscopy, we use three view directions for a conventional stereoscopic triangulation. These multi-scale Hough-wavelet analyses, stereoscopy and tomography extensions have been applied for the first time in a coronal plumes study. The temporal evolution of the mean orientation of plumes from May 2007 to April 2008 is then analyzed and discussed. Since the plume orientation is assumed to follow the coronal magnetic field, this analysis reveals: (i) a mean orientation of plumes more horizontal than for a dipole magnetic field, (ii) an asymmetry of the coronal open polar cap magnetic field from the solar rotation axis by up to 6° and (iii) a variation of these orientation and asymmetry over the year. Finally, with the help of the reconstructed 3-D geometry of the plumes, we study in detail their temporal evolution as well as the shape and size of their cross sections. The study reveals: (i) different lifetimes of plumes from 2-3 days up to 9 days and (ii) the presence of both near-circular plume cross sections and plumes with curtain-like structures. Also discussed is the plumes positions and their relation to other coronal phenomena such as coronal holes and jets. Plumes are found to be located inside coronal holes, and jets could explain the intensity enhancement within the plumes.

Some problems of Maryland towns as seen by their mayors

NASA Technical Reports Server (NTRS)

Peake, H. J.

1978-01-01

Conversations were held with the mayors of six Maryland towns to discuss possible models and needs for technology transfer. An unexpected outcome of the discussions was a considerable insight into local problems as perceived by the mayors. Problems, whether administrative, socio-economic, or technological, are different, from town to town, in degree, not in kind. Recognition of this feature of local priorities is vital to any considerations of external assistance.

Preliminary investigation of some large landslides triggered by the 2008 Wenchuan earthquake, Sichuan Province, China

USGS Publications Warehouse

Wang, F.; Cheng, Q.; Highland, L.; Miyajima, M.; Wang, Hongfang; Yan, C.

2009-01-01

The M s 8.0 Wenchuan earthquake or "Great Sichuan Earthquake" occurred at 14:28 p.m. local time on 12 May 2008 in Sichuan Province, China. Damage by earthquake-induced landslides was an important part of the total earthquake damage. This report presents preliminary observations on the Hongyan Resort slide located southwest of the main epicenter, shallow mountain surface failures in Xuankou village of Yingxiu Town, the Jiufengchun slide near Longmenshan Town, the Hongsong Hydro-power Station slide near Hongbai Town, the Xiaojiaqiao slide in Chaping Town, two landslides in Beichuan County-town which destroyed a large part of the town, and the Donghekou and Shibangou slides in Qingchuan County which formed the second biggest landslide lake formed in this earthquake. The influences of seismic, topographic, geologic, and hydro-geologic conditions are discussed. ?? 2009 Springer-Verlag.

Feel the Burn, Part II: Quantifying and mapping spectral, spatial, and temporal structures of the transition region under hot and cold coronal regions

NASA Astrophysics Data System (ADS)

Atwood, Shane; Kankelborg, Charles C.

2017-08-01

The coronal volume is filled with magnetic field, yet only part of that volume has sufficient volume to exhibit hot X-ray loops. Using XRT and AIA images, we identify footpoints of hot coronal loops. We then use IRIS rasters to compare the spatial, temporal, and spectral structure of these relatively "heated" and "unheated" regions. We seek a signature of upward-propagating energy that could be associated with hot active region loops.

Coronal Hole Facing Earth

NASA Image and Video Library

2018-05-15

An extensive equatorial coronal hole has rotated so that it is now facing Earth (May 2-4, 2018). The dark coronal hole extends about halfway across the solar disk. It was observed in a wavelength of extreme ultraviolet light. This magnetically open area is streaming solar wind (i.e., a stream of charged particles released from the sun) into space. When Earth enters a solar wind stream and the stream interacts with our magnetosphere, we often experience nice displays of aurora. https://photojournal.jpl.nasa.gov/catalog/PIA00577

Self consistent MHD modeling of the solar wind from coronal holes with distinct geometries

NASA Technical Reports Server (NTRS)

Stewart, G. A.; Bravo, S.

1995-01-01

Utilizing an iterative scheme, a self-consistent axisymmetric MHD model for the solar wind has been developed. We use this model to evaluate the properties of the solar wind issuing from the open polar coronal hole regions of the Sun, during solar minimum. We explore the variation of solar wind parameters across the extent of the hole and we investigate how these variations are affected by the geometry of the hole and the strength of the field at the coronal base.

Earth-Directed Coronal Hole

NASA Image and Video Library

2016-09-21

A dark coronal hole that was facing towards Earth for several days spewed streams of solar wind in our direction (Sept. 18-21, 2016). A coronal hole is a magnetically open region. The magnetic fields have opened up allowing solar wind (comprised of charged particles) to stream into space. Gusts of solar wind can generate beautiful aurora when they reach Earth. The video clip shows the sun in a wavelength of extreme ultraviolet light. Movies are available at http://photojournal.jpl.nasa.gov/catalog/PIA21067

A type IV burst associated with a coronal streamer disruption event

NASA Technical Reports Server (NTRS)

Kundu, M. R.

1987-01-01

A type IV burst was observed on February 17, 1985 with the Clark Lake Radio Observatory multifrequency radioheliograph operating in the frequency range 20-125 MHz. This burst was associated with a coronal streamer disruption event. From two-dimensional images produced at 50 MHz, evidence of a type II burst and a slow moving type IV burst are shown. The observations of the moving type IV burst suggests that a plasmoid containing energetic electrons can result from the disruption of a coronal streamer.

Coronal Hole Rotating Towards Us

NASA Image and Video Library

2018-05-22

A good-sized coronal hole came around to where it is just about facing Earth (May 16-18, 2018). Coronal holes are areas of open magnetic field from which solar wind (consisting of charged particles) streams into space. The video clip covers two days and was taken in a wavelength of extreme ultraviolet light. Such streams of particles take several days to reach Earth, but they can generate aurora, particularly nearer the poles. An animation is available at https://photojournal.jpl.nasa.gov/catalog/PIA00575

The Sun and the Solar Wind Close to the Sun

NASA Technical Reports Server (NTRS)

Suess, Steven T.

1998-01-01

One of the benefits from the Ulysses, SOHO, and YOHKOH missions has been a strong stimulus to better understand the magnetohydrodynamic processes involved in coronal expansion. Three topics for which this has been especially true are described here. These are: (i) The observed constancy of the radial interplanetary magnetic field strength (as mapped to constant radius). (ii) The geometric spreading of coronal plumes and coronal holes, and the fate of plumes. (iii) The plasma Beta in streamers and the physics of streamer confinement.

An Innovative Approach for Management of Vertical Coronal Fracture in Molar: Case Report

PubMed Central

Kathuria, Ambica; Kavitha, M.; Ravishankar, P.

2012-01-01

Unlike anterior teeth, acute exogenous trauma is an infrequent cause of posterior coronal vertical tooth fractures. Endodontic and restorative management of such fractures is a great challenge for the clinician. Newer advancements in adhesive techniques can provide successful intracoronal splinting of such teeth to reinforce the remaining tooth structure. This paper describes the diagnosis and management of a case of complicated vertical coronal fracture in mandibular first molar induced by a traffic accident. PMID:22567453

The Office of the Coroner

PubMed Central

McMillan, J. Stewart

1983-01-01

Society has always been concerned about deaths which do not result from natural causes. In Canada, provincial legislatures have met this concern with legislation known as the Coroners' Act in some provinces and as the Fatality Inquiries Act in others. While these statutes are not identical, their intent is the same: to ensure that all unusual deaths are fully investigated to determine their true cause. The coroner's or medical examiner's primary responsibility is to show the public how similar deaths may be avoided. PMID:21283284

Solar and interplanetary dynamics; Proceedings of the Symposium, Harvard University, Cambridge, Mass., August 27-31, 1979

NASA Technical Reports Server (NTRS)

Dryer, M. (Editor); Tandberg-Hanssen, E.

1980-01-01

The symposium focuses on solar phenomena as the source of transient events propagating through the solar system, and theoretical and observational assessments of the dynamic processes involved in these events. The topics discussed include the life history of coronal structures and fields, coronal and interplanetary responses to long time scale phenomena, solar transient phenomena affecting the corona and interplanetary medium, coronal and interplanetary responses to short time scale phenomena, and future directions.

Coronal Jets from Minifilament Eruptions in Active Regions

NASA Astrophysics Data System (ADS)

Sterling, A. C.; Martinez, F.; Falconer, D. A.; Moore, R. L.

2016-12-01

Solar coronal jets are transient (frequently of lifetime 10 min) features that shoot out from near the solar surface, become much longer than their width, and occur in all solar regions, including coronal holes, quiet Sun, and active regions (e.g., Shimojo et al. 1996, Certain et al. 2007). Sterling et al. (2015) and other studies found that in coronal holes and in quiet Sun the jets result when small-scale filaments, called ``minifilaments,'' erupt onto nearby open or high-reaching field lines. Additional studies found that coronal-jet-onset locations (and hence presumably the minifilament-eruption-onset locations) coincided with locations of magnetic-flux cancellation. For active region (AR) jets however the situation is less clear. Sterling et al. (2016) studied jets in one active region over a 24-hour period; they found that some AR jets indeed resulted from minifilament eruptions, usually originating from locations of episodes of magnetic-flux cancelation. In some cases however they could not determine whether flux was emerging or canceling at the polarity inversion line from which the minifilament erupted; and for other jets of that region minifilaments were not conclusively apparent prior to jet occurrence. Here we further study AR jets, by observing them in a single AR over a one-week period, using X-ray images from Hinode/XRT and EUV/UV images from SDO/AIA, and line-of-sight magnetograms and white-light intensity-grams from SDO/HMI. We initially identified 13 prominent jets in the XRT data, and examined corresponding AIA and HMI data. For at least several of the jets, our findings are consistent with the jets resulting from minifilament eruptions, and originating from sights of magnetic-field cancelation. Thus our findings support that, at least in many cases, AR coronal jets result from the same physical processes that produce coronal jets in quiet-Sun and coronal-hole regions. FM was supportedby the Research Experience for Undergraduates (REU) program at NASA/MSFC and the University of Alabama, Huntsville. Additional support was from the NASA HGI program and the Hinode project.

Navigated total knee arthroplasty: is it error-free?

PubMed

Chua, Kerk Hsiang Zackary; Chen, Yongsheng; Lingaraj, Krishna

2014-03-01

The aim of this study was to determine whether errors do occur in navigated total knee arthroplasty (TKAs) and to study whether errors in bone resection or implantation contribute to these errors. A series of 20 TKAs was studied using computer navigation. The coronal and sagittal alignments of the femoral and tibial cutting guides, the coronal and sagittal alignments of the final tibial implant and the coronal alignment of the final femoral implant were compared with that of the respective bone resections. To determine the post-implantation mechanical alignment of the limb, the coronal alignment of the femoral and tibial implants was combined. The median deviation between the femoral cutting guide and bone resection was 0° (range -0.5° to +0.5°) in the coronal plane and 1.0° (range -2.0° to +1.0°) in the sagittal plane. The median deviation between the tibial cutting guide and bone resection was 0.5° (range -1.0° to +1.5°) in the coronal plane and 1.0° (range -1.0° to +3.5°) in the sagittal plane. The median deviation between the femoral bone resection and the final implant was 0.25° (range -2.0° to 3.0°) in the coronal plane. The median deviation between the tibial bone resection and the final implant was 0.75° (range -3.0° to +1.5°) in the coronal plane and 1.75° (range -4.0° to +2.0°) in the sagittal plane. The median post-implantation mechanical alignment of the limb was 0.25° (range -3.0° to +2.0°). When navigation is used only to guide the positioning of the cutting jig, errors may arise in the manual, non-navigated steps of the procedure. Our study showed increased cutting errors in the sagittal plane for both the femur and the tibia, and following implantation, the greatest error was seen in the sagittal alignment of the tibial component. Computer navigation should be used not only to guide the positioning of the cutting jig, but also to check the bone resection and implant position during TKA. IV.

The injury epidemiology of cyclists based on a road trauma registry.

PubMed

Amoros, Emmanuelle; Chiron, Mireille; Thélot, Bertrand; Laumon, Bernard

2011-08-17

Bicycle use has increased in some of France's major cities, mainly as a means of transport. Bicycle crashes need to be studied, preferably by type of cycling. Here we conduct a descriptive analysis. A road trauma registry has been in use in France since 1996, in a large county around Lyon (the Rhône, population 1.6 million). It covers outpatients, inpatients and fatalities. All injuries are coded using the Abbreviated Injury Scale (AIS). Proxies were used to identify three types of cycling: learning = children (0-10 years old); sports cycling = teenagers and adults injured outside towns; cycling as means of transport = teenagers and adults injured in towns. The study is based on 13,684 cyclist casualties (1996-2008). The percentage of cyclists injured in a collision with a motor vehicle was 8% among children, 17% among teenagers and adults injured outside towns, and 31% among those injured in towns. The percentage of serious casualties (MAIS 3+) was 4.5% among children, 10.9% among adults injured outside towns and 7.2% among those injured in towns. Collisions with motor-vehicles lead to more internal injuries than bicycle-only crashes. The description indicates that cyclist type is associated with different crash and injury patterns. In particular, cyclists injured in towns (where cycling is increasing) are generally less severely injured than those injured outside towns for both types of crash (bicycle-only crashes and collisions with a motor vehicle). This is probably due to lower speeds in towns, for both cyclists and motor vehicles.

An experimental study of a change from over-the-counter to self-service sales of alcoholic beverages in monopoly outlets.

PubMed

Skog, O J

2000-01-01

To evaluate if a change from over-the-counter to self-service sales of alcoholic beverages in monopoly outlets has an impact on the sales volume. Fourteen Swedish towns were selected, each having only one state-run monopoly shop selling alcoholic beverages. Seven pairs were formed by matching towns in terms of demographic and economic criteria, and according to sales of alcoholic beverages. Within each pair, one town continued with the traditional over-the-counter sales, while the other switched to self-service sales of beer, wine and spirits. This was decided by randomization. The effect of switching to self-service was evaluated by comparing monthly sales volume of experimental and control towns over an extended period of time. In order to evaluate changes due to transfer of customers from neighboring towns, the sales statistics in these towns were analyzed. In two towns, this transfer was also evaluated with the aid of customer surveys before and after the change. It was found that the change produced an increase in sales volume of 17%. The increase was permanent. Approximately one half of the increase could be explained by an inflow of new customers from neighboring towns. The self-service shops became quite popular among the customers, and sales volume increased substantially. About one half of the increase appears to be due to new customers from neighboring towns. The remaining increase may be due to increased consumption by the local residents. Thus, the results seem to confirm the hypothesis that the physical availability of alcoholic beverages may affect consumption levels.

The injury epidemiology of cyclists based on a road trauma registry

PubMed Central

2011-01-01

Background Bicycle use has increased in some of France's major cities, mainly as a means of transport. Bicycle crashes need to be studied, preferably by type of cycling. Here we conduct a descriptive analysis. Method A road trauma registry has been in use in France since 1996, in a large county around Lyon (the Rhône, population 1.6 million). It covers outpatients, inpatients and fatalities. All injuries are coded using the Abbreviated Injury Scale (AIS). Proxies were used to identify three types of cycling: learning = children (0-10 years old); sports cycling = teenagers and adults injured outside towns; cycling as means of transport = teenagers and adults injured in towns. The study is based on 13,684 cyclist casualties (1996-2008). Results The percentage of cyclists injured in a collision with a motor vehicle was 8% among children, 17% among teenagers and adults injured outside towns, and 31% among those injured in towns. The percentage of serious casualties (MAIS 3+) was 4.5% among children, 10.9% among adults injured outside towns and 7.2% among those injured in towns. Collisions with motor-vehicles lead to more internal injuries than bicycle-only crashes. Conclusion The description indicates that cyclist type is associated with different crash and injury patterns. In particular, cyclists injured in towns (where cycling is increasing) are generally less severely injured than those injured outside towns for both types of crash (bicycle-only crashes and collisions with a motor vehicle). This is probably due to lower speeds in towns, for both cyclists and motor vehicles. PMID:21849071

Acceptability of residential development in a regional landscape: Potential effects on wildlife occupancy patterns

USGS Publications Warehouse

Bettigole, Charles A.; Donovan, Therese; Manning, Robert; Austin, John; Long, Robert

2014-01-01

The conversion of natural lands to developed uses may pose the single greatest human threat to global terrestrial biodiversity. Continued human growth and development over the next century will further exacerbate these effects of habitat loss and fragmentation. Natural resource managers are tasked with managing wildlife as a public trust, yet often have little say in land use decisions. Generally speaking, decision makers could benefit from an understanding of what different regulations mean in terms of wildlife distribution. In a previous paper (Bettigole et al., 2013), we surveyed town residents throughout Vermont to measure how respondents feel about a range of development levels within their town boundaries. We estimated the “social carrying capacity for development” – orSKd – for 251 towns in Vermont. SKd provides an estimate of the level of developed land cover classes that town residents deem “acceptable” within their town boundaries. In this paper, we design a framework for linking the town-specific SKd estimates with the wildlife distribution patterns for three wide-ranging mammalian species: American black bear (Ursus americanus), fisher (Martes pennanti), and bobcat (Lynx rufus). We simulated landscape conditions at SKd for each town in Vermont, and then used existing occupancy models for the three target species to spatially map and compare occupancy rates in the baseline year 2000 with occupancy rates at SKd. With nearly 90% of Vermont towns willing to increase developed landcover classes within town boundaries compared to baseline levels, significant state-wide changes in occupancy rates were predicted for all three focal species. Average occupancy rates declined by −15.9% and −3.1% for black bear and bobcats, respectively. Average occupancy rates for fisher increased by 9.0%. This study provides a method for linking development standards within a town with wildlife occurrence. Across towns, the methodology spatially identifies areas that may be at risk of future development, as well as identifying areas where wildlife distribution patterns may face future change as a result of increased human population growth and development.

Photoacoustic imaging to detect rat brain activation after cocaine hydrochloride injection

NASA Astrophysics Data System (ADS)

Jo, Janggun; Yang, Xinmai

2011-03-01

Photoacoustic imaging (PAI) was employed to detect small animal brain activation after the administration of cocaine hydrochloride. Sprague Dawley rats were injected with different concentrations (2.5, 3.0, and 5.0 mg per kg body) of cocaine hydrochloride in saline solution through tail veins. The brain functional response to the injection was monitored by photoacoustic tomography (PAT) system with horizontal scanning of cerebral cortex of rat brain. Photoacoustic microscopy (PAM) was also used for coronal view images. The modified PAT system used multiple ultrasonic detectors to reduce the scanning time and maintain a good signal-to-noise ratio (SNR). The measured photoacoustic signal changes confirmed that cocaine hydrochloride injection excited high blood volume in brain. This result shows PAI can be used to monitor drug abuse-induced brain activation.

Turbulence-driven Coronal Heating and Improvements to Empirical Forecasting of the Solar Wind

NASA Astrophysics Data System (ADS)

Woolsey, Lauren N.; Cranmer, Steven R.

2014-06-01

Forecasting models of the solar wind often rely on simple parameterizations of the magnetic field that ignore the effects of the full magnetic field geometry. In this paper, we present the results of two solar wind prediction models that consider the full magnetic field profile and include the effects of Alfvén waves on coronal heating and wind acceleration. The one-dimensional magnetohydrodynamic code ZEPHYR self-consistently finds solar wind solutions without the need for empirical heating functions. Another one-dimensional code, introduced in this paper (The Efficient Modified-Parker-Equation-Solving Tool, TEMPEST), can act as a smaller, stand-alone code for use in forecasting pipelines. TEMPEST is written in Python and will become a publicly available library of functions that is easy to adapt and expand. We discuss important relations between the magnetic field profile and properties of the solar wind that can be used to independently validate prediction models. ZEPHYR provides the foundation and calibration for TEMPEST, and ultimately we will use these models to predict observations and explain space weather created by the bulk solar wind. We are able to reproduce with both models the general anticorrelation seen in comparisons of observed wind speed at 1 AU and the flux tube expansion factor. There is significantly less spread than comparing the results of the two models than between ZEPHYR and a traditional flux tube expansion relation. We suggest that the new code, TEMPEST, will become a valuable tool in the forecasting of space weather.

Town Flush with Benefits from New Water System

EPA Pesticide Factsheets

An EPA-funded project to replace the aging and undersized water lines in a Virginia town has transformed the community–providing cost savings, improved water quality and greater public safety, while eliminating leaks that drained half of the town' water.

Energy balance and stability. [in stellar coronae

NASA Technical Reports Server (NTRS)

Hammer, R.

1982-01-01

The energy balance of the outer atmospheres of solarlike stars is discussed. The energy balance of open coronal regions is considered, discussing the construction and characteristics of models of such regions in some detail. In particular, the temperature as a function of height is considered, as are the damping length dependence of the global energy balance in the region between the base of the transition region and the critical point, and the effects of changing the amount of coronal heating, the stellar mass, and the stellar radius. Models of coronal loops are more briefly discussed. The chromosphere is then included in the discussion of the energy balance, and the connection between global energy balance and global thermal stability is addressed. The observed positive correlations between the chromospheric and coronal energy losses and the pressure of the transition region is qualitatively explained.

Characteristics of the Time Variable Component of the Coronal Heating Process

NASA Technical Reports Server (NTRS)

Habbal, Shadia R.; Poland, Art (Technical Monitor)

2001-01-01

The goal of the proposed study was to explore the non-steady nature of the coronal heating processes and its manifestations in the inner corona and interplanetary space by coordinating coronal SOHO observations in white light, ultraviolet, and extreme ultraviolet, with complementary radio occultation measurements during an unprecedented and rare coincidence of a total solar eclipse with the superior conjunction of a planetary spacecraft, Galileo, in February 1998. In addition, radio occultation measurements by the Mars Global Surveyor spacecraft in May 1998 spanned the inner heliosphere observed by coronal SOHO instruments and probing it to within 0.5 R(sub S), above the solar surface. Inferences of physical properties derived from these simultaneous observations were subsequently used in solar wind model computations to yield the range of plasma parameters characteristic of the fast and slow solar wind.

Coronal holes and high-speed wind streams

NASA Technical Reports Server (NTRS)

Zirker, J. B.

1977-01-01

Coronal holes, regions of unusually low density and low temperature in the solar corona, are identified as Bartel's M regions, i.e., sources of high-speed wind streams that produce recurrent geomagnetic variations. Throughout the Skylab period the polar caps of the sun were coronal holes, and at lower latitudes the most persistent and recurrent holes were equatorial extensions of the polar caps. The holes rotated 'rigidly' at the equatorial synodic rate. They formed in regions of unipolar photospheric magnetic field, and their internal magnetic fields diverged rapidly with increasing distance from the sun. The geometry of the magnetic field in the inner corona seems to control both the physical properties of the holes and the global distribution of high-speed wind streams in the heliosphere. Phenomenological models for the birth and decay of coronal holes have been proposed.

Relation of large-scale coronal X-ray structure and cosmic rays. I - Sources of solar wind streams as defined by X-ray emission and H-alpha absorption features

NASA Technical Reports Server (NTRS)

Krieger, A. S.; Nolte, J. T.; Sullivan, J. D.; Lazarus, A. J.; Mcintosh, P. S.; Gold, R. E.; Roelof, E. C.

1975-01-01

The large-scale structure of the corona and the interplanetary medium during Carrington rotations 1601-1607 is discussed relative to recurrent high-speed solar wind streams and their coronal sources. Only streams A, C, D, and F recur on more than one rotation. Streams A and D are associated with coronal holes, while C and F originate in the high corona (20-50 solar radii) over faint X-ray emissions. The association of the streams with holes is confirmed by earlier findings that there are no large equatorial holes without an associated high-speed stream and that the area of the equatorial region of coronal holes is highly correlated with the maximum velocity observed in the associated stream near 1 AU.

The structure and evolution of coronal holes

NASA Technical Reports Server (NTRS)

Timothy, A. F.; Krieger, A. S.; Vaiana, G. S.

1975-01-01

Soft X-ray observations of coronal holes are analyzed to determine the structure, temporal evolution, and rotational properties of those features as well as possible mechanisms which may account for their almost rigid rotational characteristics. It is shown that coronal holes are open features with a divergent magnetic-field configuration resulting from a particular large-scale magnetic-field topology. They are apparently formed when the successive emergence and dispersion of active-region fields produce a swath of unipolar field founded by fields of opposite polarity, and they die when large-scale field patterns emerge which significantly distort the original field configuration. Two types of holes are described (compact and elongated), and three possible rotation mechanisms are considered: a rigidly rotating subphotospheric phenomenon, a linking of high and low latitudes by closed field lines, and an interaction between moving coronal material and open field lines.

Results from CoMStOC - The Coronal Magnetic Structures Observing Campaign

NASA Technical Reports Server (NTRS)

Schmelz, J. T.; Holman, G. D.

1991-01-01

The Coronal Magnetic Structures Observing Campaign (CoMStOC) was designed to measure the magnetic field strength and determine its structure in the solar corona. Simultaneous soft X-ray and microwave observations were taken by the Solar Maximum Mission's X-ray Polychromator (XRP) and the Very Large Array (VLA) on four days in the campaign period (Nov 25 to Dec 21, 1987). XRP maps in soft X-ray resonance lines formed at different coronal temperatures provide accurate temperature and emission measure diagnostics. VLA maps at several frequencies in the 20 cm and 6 cm bands yield information on microwave structure, spectrum and polarization. The combined data set separates contributions from the two dominant microwave emission mechanisms, thermal bremsstrahlung and gyroresonance. Where gyroresonance dominates, the coronal magnetic field strength has been determined with the aid of theoretical modeling.

Results from CoMStOC - The Coronal Magnetic Structures Observing Campaign

NASA Astrophysics Data System (ADS)

Schmelz, J. T.; Holman, G. D.

The Coronal Magnetic Structures Observing Campaign (CoMStOC) was designed to measure the magnetic field strength and determine its structure in the solar corona. Simultaneous soft X-ray and microwave observations were taken by the Solar Maximum Mission's X-ray Polychromator (XRP) and the Very Large Array (VLA) on four days in the campaign period (Nov 25 to Dec 21, 1987). XRP maps in soft X-ray resonance lines formed at different coronal temperatures provide accurate temperature and emission measure diagnostics. VLA maps at several frequencies in the 20 cm and 6 cm bands yield information on microwave structure, spectrum and polarization. The combined data set separates contributions from the two dominant microwave emission mechanisms, thermal bremsstrahlung and gyroresonance. Where gyroresonance dominates, the coronal magnetic field strength has been determined with the aid of theoretical modeling.

Extreme-ultraviolet observations of global coronal wave rotation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Attrill, G. D. R.; Long, D. M.; Green, L. M.

2014-11-20

We present evidence of global coronal wave rotation in EUV data from SOHO/EIT, STEREO/EUVI, and SDO/AIA. The sense of rotation is found to be consistent with the helicity of the source region (clockwise for positive helicity, anticlockwise for negative helicity), with the source regions hosting sigmoidal structures. We also study two coronal wave events observed by SDO/AIA where no clear rotation (or sigmoid) is observed. The selected events show supporting evidence that they all originate with flux rope eruptions. We make comparisons across this set of observations (both with and without clear sigmoidal structures). On examining the magnetic configuration ofmore » the source regions, we find that the nonrotation events possess a quadrupolar magnetic configuration. The coronal waves that do show a rotation originate from bipolar source regions.« less

Force-Free Magnetic Fields Calculated from Automated Tracing of Coronal Loops with AIA/SDO

NASA Astrophysics Data System (ADS)

Aschwanden, M. J.

2013-12-01

One of the most realistic magnetic field models of the solar corona is a nonlinear force-free field (NLFFF) solution. There exist about a dozen numeric codes that compute NLFFF solutions based on extrapolations of photospheric vector magnetograph data. However, since the photosphere and lower chromosphere is not force-free, a suitable correction has to be applied to the lower boundary condition. Despite of such "pre-processing" corrections, the resulting theoretical magnetic field lines deviate substantially from observed coronal loop geometries. - Here we developed an alternative method that fits an analytical NLFFF approximation to the observed geometry of coronal loops. The 2D coordinates of the geometry of coronal loop structures observed with AIA/SDO are traced with the "Oriented Coronal CUrved Loop Tracing" (OCCULT-2) code, an automated pattern recognition algorithm that has demonstrated the fidelity in loop tracing matching visual perception. A potential magnetic field solution is then derived from a line-of-sight magnetogram observed with HMI/SDO, and an analytical NLFFF approximation is then forward-fitted to the twisted geometry of coronal loops. We demonstrate the performance of this magnetic field modeling method for a number of solar active regions, before and after major flares observed with SDO. The difference of the NLFFF and the potential field energies allows us then to compute the free magnetic energy, which is an upper limit of the energy that is released during a solar flare.

The Relation between Coronal Holes and Coronal Mass Ejections during the Rise, Maximum, and Declining Phases of Solar Cycle 23

NASA Technical Reports Server (NTRS)

Mohamed, A. A.; Gopalswamy, N; Yashiro, S.; Akiyama, S.; Makela, P.; Xie, H.; Jung, H.

2012-01-01

We study the interaction between coronal holes (CHs) and coronal mass ejections (CMEs) using a resultant force exerted by all the coronal holes present on the disk and is defined as the coronal hole influence parameter (CHIP). The CHIP magnitude for each CH depends on the CH area, the distance between the CH centroid and the eruption region, and the average magnetic field within the CH at the photospheric level. The CHIP direction for each CH points from the CH centroid to the eruption region. We focus on Solar Cycle 23 CMEs originating from the disk center of the Sun (central meridian distance =15deg) and resulting in magnetic clouds (MCs) and non-MCs in the solar wind. The CHIP is found to be the smallest during the rise phase for MCs and non-MCs. The maximum phase has the largest CHIP value (2.9 G) for non-MCs. The CHIP is the largest (5.8 G) for driverless (DL) shocks, which are shocks at 1 AU with no discernible MC or non-MC. These results suggest that the behavior of non-MCs is similar to that of the DL shocks and different from that of MCs. In other words, the CHs may deflect the CMEs away from the Sun-Earth line and force them to behave like limb CMEs with DL shocks. This finding supports the idea that all CMEs may be flux ropes if viewed from an appropriate vantage point.

Solar Magnetic Carpet III: Coronal Modelling of Synthetic Magnetograms

NASA Astrophysics Data System (ADS)

Meyer, K. A.; Mackay, D. H.; van Ballegooijen, A. A.; Parnell, C. E.

2013-09-01

This article is the third in a series working towards the construction of a realistic, evolving, non-linear force-free coronal-field model for the solar magnetic carpet. Here, we present preliminary results of 3D time-dependent simulations of the small-scale coronal field of the magnetic carpet. Four simulations are considered, each with the same evolving photospheric boundary condition: a 48-hour time series of synthetic magnetograms produced from the model of Meyer et al. ( Solar Phys. 272, 29, 2011). Three simulations include a uniform, overlying coronal magnetic field of differing strength, the fourth simulation includes no overlying field. The build-up, storage, and dissipation of magnetic energy within the simulations is studied. In particular, we study their dependence upon the evolution of the photospheric magnetic field and the strength of the overlying coronal field. We also consider where energy is stored and dissipated within the coronal field. The free magnetic energy built up is found to be more than sufficient to power small-scale, transient phenomena such as nanoflares and X-ray bright points, with the bulk of the free energy found to be stored low down, between 0.5 - 0.8 Mm. The energy dissipated is currently found to be too small to account for the heating of the entire quiet-Sun corona. However, the form and location of energy-dissipation regions qualitatively agree with what is observed on small scales on the Sun. Future MHD modelling using the same synthetic magnetograms may lead to a higher energy release.

Standing Kink modes in three-dimensional coronal loops

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pascoe, D. J.; De Moortel, I., E-mail: dpascoe@mcs.st-andrews.ac.uk

2014-04-01

So far, the straight flux tube model proposed by Edwin and Roberts is the most commonly used tool in practical coronal seismology, in particular, to infer values of the (coronal) magnetic field from observed, standing kink mode oscillations. In this paper, we compare the period predicted by this basic model with three-dimensional (3D) numerical simulations of standing kink mode oscillations, as the period is a crucial parameter in the seismological inversion to determine the magnetic field. We perform numerical simulations of standing kink modes in both straight and curved 3D coronal loops and consider excitation by internal and external drivers.more » The period of oscillation for the displacement of dense coronal loops is determined by the loop length and the kink speed, in agreement with the estimate based on analytical theory for straight flux tubes. For curved coronal loops embedded in a magnetic arcade and excited by an external driver, a secondary mode with a period determined by the loop length and external Alfvén speed is also present. When a low number of oscillations is considered, these two periods can result in a single, non-resolved (broad) peak in the power spectrum, particularly for low values of the density contrast for which the two periods will be relatively similar. In that case (and for this particular geometry), the presence of this additional mode would lead to ambiguous seismological estimates of the magnetic field strength.« less

Does velopharyngeal closure pattern affect the success of pharyngeal flap pharyngoplasty?

PubMed

Armour, Alexis; Fischbach, Simone; Klaiman, Paula; Fisher, David M

2005-01-01

Historically at The Hospital for Sick Children in Toronto, pharyngeal flap pharyngoplasty has been the treatment of choice for treatment of velopharyngeal insufficiency, regardless of velopharyngeal closure pattern. The authors hypothesize that pharyngeal flap pharyngoplasty is more effective in treating velopharyngeal insufficiency in patients with circular or sagittal velopharyngeal closure and less effective in treating the coronal closure pattern. Ninety-three patients who underwent superiorly based pharyngeal flap surgery for velopharyngeal insufficiency were evaluated in a retrospective chart review. Closure pattern was determined preoperatively by nasopharyngoscopy or multiview videofluoroscopy. Nasalance was assessed preoperatively and at 6 weeks and 1 year postoperatively. Nasalance during nonnasal speech was decreased on average, for all closure patterns, postoperatively. However, a significantly higher percentage of patients were corrected to normal nasalance scores in thenoncoronal group than in the coronal group (57 percent versus 35 percent, respectively) at 1 year postoperatively (p < 0.05). Surgical overcorrection, as determined by postoperative hyponasality, occurred at a rate of 13 percent in the coronal group versus 7 percent in the noncoronal group (not statistically significant). The results demonstrate that hypernasality in patients with a coronal velopharyngeal closure pattern can be improved by pharyngeal flap pharyngoplasty. This procedure, however, is more frequently effective in correcting noncoronal closure pattern velopharyngeal insufficiency than coronal pattern velopharyngeal insufficiency. The authors are now more selective in their approach to the management of velopharyngeal insufficiency and are more inclined to treat coronal pattern velopharyngeal insufficiency with sphincter pharyngoplasty.

Temporal variations of solar EUV, UV, and 10,830-A radiations

NASA Technical Reports Server (NTRS)

Donnelly, R. F.; Hinteregger, H. E.; Heath, D. F.

1986-01-01

The temporal characteristics of the full-disk chromospheric EUV fluxes agree well with those of the ground-based measurements of the chromospheric He I absorption line at 10,830 A and differ systematically from those of the coronal EUV and 10.7-cm flux. The ratio of the flux increase during the rise of solar cycle 21 to that during solar rotation variations is uniformly high for the chromospheric EUV and corroborating 10,830-A fluxes, highest for the transition region and 'cool' coronal EUV fluxes (T less than 2 x 10 to the 6th K), and lowest for the 'hot' coronal EUV and 10.7-cm flux. The rise and decay rates of episodes of major activity progress from those for the hot coronal EUV lines and the 10.7-cm flux to slower values for the chromospheric H Lyman alpha line, 10,830-A line, and photospheric 2050-A UV flux. It is suggested that active region remnants contribute significantly to the solar cycle increase and during the decay of episodes of major activity. The ratio of power in 13-day periodicity to that for 27 days in high (1/3) for the photospheric UV flux, medium (1/6) for the chromospheric EUV and 10,830-A fluxes, and small to negligible for the hot coronal EUV fluxes. These ratios are used to estimate the dependence of active region emission on the solar central meridian distance for chromospheric and coronal EUV flux.

Energy Input Flux in the Global Quiet-Sun Corona

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mac Cormack, Cecilia; Vásquez, Alberto M.; López Fuentes, Marcelo

We present first results of a novel technique that provides, for the first time, constraints on the energy input flux at the coronal base ( r ∼ 1.025 R {sub ⊙}) of the quiet Sun at a global scale. By combining differential emission measure tomography of EUV images, with global models of the coronal magnetic field, we estimate the energy input flux at the coronal base that is required to maintain thermodynamically stable structures. The technique is described in detail and first applied to data provided by the Extreme Ultraviolet Imager instrument, on board the Solar TErrestrial RElations Observatory mission,more » and the Atmospheric Imaging Assembly instrument, on board the Solar Dynamics Observatory mission, for two solar rotations with different levels of activity. Our analysis indicates that the typical energy input flux at the coronal base of magnetic loops in the quiet Sun is in the range ∼0.5–2.0 × 10{sup 5} (erg s{sup −1} cm{sup −2}), depending on the structure size and level of activity. A large fraction of this energy input, or even its totality, could be accounted for by Alfvén waves, as shown by recent independent observational estimates derived from determinations of the non-thermal broadening of spectral lines in the coronal base of quiet-Sun regions. This new tomography product will be useful for the validation of coronal heating models in magnetohydrodinamic simulations of the global corona.« less

Development of coronal cementum in hypsodont horse cheek teeth.

PubMed

Sahara, Noriyuki

2014-04-01

The horse is a grazing herbivore whose cheek teeth are hypsodon; that is, they possess long crowns that are completely covered by coronal cement at eruption. For elucidation of the sequential events in the formation of this coronal cementum in the mandibular horse cheek teeth, in the present study the lower 3rd permanent premolar teeth (PM4 ) from 3.5-, 4-, and 5-year-old horses were compared by using radiography, microcomputed tomography (Miro-CT), light microscopy (LM), and scanning electron microscopy (SEM). The present study clearly showed that prior to coronal cementogenesis tartrate-resistant acid phosphatase (TRAP)-positive odontoclasts resorbed on the enamel surface of the reserve crown in horse cheek tooth. Enamel resorption areas were relatively narrow, and started from the cuspal tips, and moved in the apical direction during tooth development. A primary cementum was initially deposited on the irregularly pitted enamel-cementum junction (ECJ) of the infolding and peripheral enamel. The infolding cementum filled grooves completely by the time of tooth eruption. On the other hand, in the peripheral cementum, the secondary and tertiary cementum layers were sequentially deposited on the primary cementum. These two cementum layers were sites for the insertion of the periodontal ligaments, and were continually laid down on the primary cementum coronally rather than apically throughout the life. The results of the present study suggest that the coronal cementum of horse cheek teeth is a multistructural and multifunctional tissue, meeting the requirements of its many different functions. Copyright © 2014 Wiley Periodicals, Inc.

Suppression of Heating of Coronal Loops Rooted in Opposite Polarity Sunspot Umbrae

NASA Technical Reports Server (NTRS)

Tiwari, Sanjiv K.; Thalmann, Julia K.; Moore, Ronald L.; Panesar, Navdeep K.; Winebarger, Amy R.

2016-01-01

EUV observations of active region (AR) coronae reveal the presence of loops at different temperatures. To understand the mechanisms that result in hotter or cooler loops, we study a typical bipolar AR, near solar disk center, which has moderate overall magnetic twist and at least one fully developed sunspot of each polarity. From AIA 193 and 94 Å images we identify many clearly discernible coronal loops that connect plage or a sunspot of one polarity to an opposite-­polarity plage region. The AIA 94 Å images show dim regions in the umbrae of the spots. To see which coronal loops are rooted in a dim umbral area, we performed a non-linear force-free field (NLFFF) modeling using photospheric vector magnetic field measurements obtained with the Heliosesmic Magnetic Imager (HMI) onboard SDO. The NLFFF model, validated by comparison of calculated model field lines with observed loops in AIA 193 and 94 Å, specifies the photospheric roots of the model field lines. Some model coronal magnetic field lines arch from the dim umbral area of the positive-polarity sunspot to the dim umbral area of a negative-polarity sunspot. Because these coronal loops are not visible in any of the coronal EUV and X-ray images of the AR, we conclude they are the coolest loops in the AR. This result suggests that the loops connecting opposite polarity umbrae are the least heated because the field in umbrae is so strong that the convective braiding of the field is strongly suppressed.

Observations of Upward Propagating Waves in the Transition Region and Corona above Sunspots

NASA Astrophysics Data System (ADS)

Hou, Zhenyong; Huang, Zhenghua; Xia, Lidong; Li, Bo; Fu, Hui

2018-03-01

We present observations of persistent oscillations of some bright features in the upper-chromosphere/transition region above sunspots taken by IRIS SJ 1400 Å and upward propagating quasi-periodic disturbances along coronal loops rooted in the same region taken by the AIA 171 Å passband. The oscillations of the features are cyclic oscillatory motions without any obvious damping. The amplitudes of the spatial displacements of the oscillations are about 1″. The apparent velocities of the oscillations are comparable to the sound speed in the chromosphere, but the upward motions are slightly larger than that of the downward. The intensity variations can take 24%–53% of the background, suggesting nonlinearity of the oscillations. The FFT power spectra of the oscillations show a dominant peak at a period of about 3 minutes, which is consistent with the omnipresent 3 minute oscillations in sunspots. The amplitudes of the intensity variations of the upward propagating coronal disturbances are 10%–15% of the background. The coronal disturbances have a period of about 3 minutes, and propagate upward along the coronal loops with apparent velocities in a range of 30 ∼ 80 km s‑1. We propose a scenario in which the observed transition region oscillations are powered continuously by upward propagating shocks, and the upward propagating coronal disturbances can be the recurrent plasma flows driven by shocks or responses of degenerated shocks that become slow magnetic-acoustic waves after heating the plasma in the coronal loops at their transition-region bases.

The Three-part Structure of a Filament-unrelated Solar Coronal Mass Ejection

NASA Astrophysics Data System (ADS)

Song, H. Q.; Cheng, X.; Chen, Y.; Zhang, J.; Wang, B.; Li, L. P.; Li, B.; Hu, Q.; Li, G.

2017-10-01

Coronal mass ejections (CMEs) often exhibit the typical three-part structure in the corona when observed with white-light coronagraphs, I.e., the bright leading front, dark cavity, and bright core, corresponding to a high-low-high density sequence. As CMEs result from eruptions of magnetic flux ropes (MFRs), which can possess either lower (e.g., coronal-cavity MFRs) or higher (e.g., hot-channel MFRs) density compared to their surroundings in the corona, the traditional opinion regards the three-part structure as the manifestations of coronal plasma pileup (high density), coronal-cavity MFR (low density), and filament (high density) contained in the trailing part of MFR, respectively. In this paper, we demonstrate that filament-unrelated CMEs can also exhibit the classical three-part structure. The observations were made from different perspectives through an event that occurred on 2011 October 4. The CME cavity corresponds to the low-density zone between the leading front and the high-density core, and it is obvious in the low corona and gradually becomes fuzzy when propagating outward. The bright core corresponds to a high-density structure that is suggested to be an erupting MFR. The MFR is recorded from both edge-on and face-on perspectives, exhibiting different morphologies that are due to projection effects. We stress that the zone (MFR) with lower (higher) density in comparison to the surroundings can appear as the dark cavity (bright core) when observed through white-light coronagraphs, which is not necessarily the coronal-cavity MFR (erupted filament).

The impact of deprivation on youth violence: a comparison of cities and their feeder towns.

PubMed

Jones, S J; Sivarajasingam, V; Shepherd, J

2011-06-01

66,000 children and adolescents are treated at emergency departments (EDs) in England and Wales each year for assault injury. The aim of this study was to compare adolescent assault injury rates in cities and towns and determine how assault injury varies with deprivation and gender. The study was set in three cities in Wales, UK, and their surrounding towns. Subjects were 11-17 year olds treated for assault injury at one of seven EDs from 1 October 2005 to 30 September 2006. Area of residence (electoral divisions, EDivs) was identified from patient postcode. EDivs were aggregated into deprivation fifths for males and females and cities and towns. Assault injury rates, rate ratios and 95% CIs were calculated. 1472 children and adolescents of 11-17 years old were treated for assault injury. Male city assault injury rates were 14.2/1000 11-17 year olds; and 13.1 in towns. Female city assault injury rates were 6.0; and 5.6 in towns. In the most deprived city areas males had assault injury rates 2.6 times (95% CI 1.85 to 3.59) that of the most affluent, compared with 2.0 times in towns (95% CI 1.39 to 2.86). For females, the most deprived city areas had assault injury rates 5.3 times that of the most affluent (95% CI 2.93 to 9.41), compared with 2.8 times in towns (95% CI 1.47 to 5.28). Injury in youth violence increased with increasing deprivation in cities and their feeder towns. This was true for boys and girls, though rates for boys were consistently higher. This link between assault injury and deprivation was stronger for girls in cities than in feeder towns. Strategies to prevent youth violence need to include improved safeguarding arrangements for girls living in the most deprived city areas.

Not just a rural occurrence: differences in agricultural equipment crash characteristics by rural-urban crash site and proximity to town.

PubMed

Harland, Karisa K; Greenan, Mitchell; Ramirez, Marizen

2014-09-01

Although approximately one-third of agricultural equipment-related crashes occur near town, these crashes are thought to be a rural problem. This analysis examines differences between agricultural equipment-related crashes by their urban-rural distribution and distance from a town. Agricultural equipment crashes were collected from nine Midwest Departments of Transportation (2005-2008). Crash zip code was assigned as urban or rural (large, small and isolated) using Rural-Urban Commuting Areas. Crash proximity to a town was estimated with ArcGIS. Multivariable logistic regression was used to estimate the odds of crashing in an urban versus rural zip codes and across rural gradients. ANOVA analysis estimated mean distance (miles) from a crash site to a town. Over four years, 4444 crashes involved agricultural equipment. About 30% of crashes occurred in urban zip codes. Urban crashes were more likely to be non-collisions (aOR=1.69[1.24-2.30]), involve ≥2 vehicles (2 vehicles: aOR=1.58[1.14-2.20], 3+ vehicles: aOR=1.68[0.98-2.88]), occur in a town (aOR=2.06[1.73-2.45]) and within one mile of a town (aOR=1.65[1.40-1.95]) than rural crashes. The proportion of crashes within a town differed significantly across rural gradients (P<0.0001). Small rural crashes, compared to isolated rural crashes, were 1.98 (95%CI[1.28-3.06]) times more likely to be non-collisions. The distance from the crash to town differed significantly by the urban-rural distribution (P<0.0001). Crashes with agricultural equipment are unexpectedly common in urban areas and near towns and cities. Education among all roadway users, increased visibility of agricultural equipment and the development of complete rural roads are needed to increase road safety and prevent agricultural equipment-related crashes. Copyright © 2014 Elsevier Ltd. All rights reserved.

No gynecologist in town: the gynecological care of women in rural Taiwan

PubMed Central

Lai, Li-Jung; Chou, Chia-Lin; Su, H Irene; Chen, Tzeng-Ji; Chou, Li-Fang; Chou, Yueh-Ching; Hwang, Shinn-Jang; Yu, Hann-Chin

2015-01-01

Background A shortage of gynecologists exists in many countries. Even within an affluent country, gynecological clinics might not be evenly distributed. The purpose of the study was to investigate the disparity in gynecological care between adult women living in towns with and without gynecologists in Taiwan. Methods Data sources were the cohort datasets of the National Health Insurance Research Database, with claims data of 1 million beneficiaries in 2010. A woman’s residency was operationally inferred from the locations where she had most frequently visited physicians’ clinics or local community hospitals within the year. Results In Taiwan, 145 (39.4%) of 368 towns had no practicing gynecologist. Of 382,167 women with health care use in the datasets, 21,794 (5.7%) lived in towns without a gynecologist. The overwhelming majority of these towns lay in sparsely populated, rural areas. During the year, 132,702 women (34.7%) had sought medical help for gynecological diseases and 113,698 (29.8%) had visited gynecologists for gynecological diseases. Women in towns without a gynecologist were less likely to consult for gynecological diseases (23.8% versus 35.4%; P<0.001) and visit gynecologists (18.7% versus 30.4%; P<0.001) than women in towns with a gynecologist. The disparity existed in each age group. Among 5,189 adult women living in towns without a gynecologist and having gynecological diseases, 78.5% (number [n]=4,074) visited gynecologists out of town, especially for infertility, benign disorders of the uterus and ovaries, gynecological examinations, and contraceptive problems, and by contrast 23.3% (n=1,209) visited nongynecologists in town, most commonly for menopausal disorders, endometriosis and pelvic pain, menstrual disorders and hormonal dysfunction, and genital dysplasia. Conclusion Gynecological care of rural women was adversely affected by the shortage of gynecologists. The consequences of accessibility in underserved areas deserve further investigation. PMID:26251581

Simulating the conversion of rural settlements to town land based on multi-agent systems and cellular automata.

PubMed

Liu, Yaolin; Kong, Xuesong; Liu, Yanfang; Chen, Yiyun

2013-01-01

Rapid urbanization in China has triggered the conversion of land from rural to urban use, particularly the conversion of rural settlements to town land. This conversion is the result of the joint effects of the geographic environment and agents involving the government, investors, and farmers. To understand the dynamic interaction dominated by agents and to predict the future landscape of town expansion, a small town land-planning model is proposed based on the integration of multi-agent systems (MAS) and cellular automata (CA). The MAS-CA model links the decision-making behaviors of agents with the neighbor effect of CA. The interaction rules are projected by analyzing the preference conflicts among agents. To better illustrate the effects of the geographic environment, neighborhood, and agent behavior, a comparative analysis between the CA and MAS-CA models in three different towns is presented, revealing interesting patterns in terms of quantity, spatial characteristics, and the coordinating process. The simulation of rural settlements conversion to town land through modeling agent decision and human-environment interaction is very useful for understanding the mechanisms of rural-urban land-use change in developing countries. This process can assist town planners in formulating appropriate development plans.

Guidelines for Speed Reduction in Towns Along Rural Highways

DOT National Transportation Integrated Search

2013-10-01

This report presents the results of the study undertaken to develop a guideline for setting up speed limit in towns along rural highways of Nevada. Generally, speed zones are provided in towns along rural highways to reduce speed-related crashes. How...

77 FR 25495 - Proposed Flood Hazard Determinations

Federal Register 2010, 2011, 2012, 2013, 2014

2012-04-30

... Docket No. FEMA-B-1250, to Luis Rodriguez, Chief, Engineering Management Branch, Federal Insurance [email protected] . FOR FURTHER INFORMATION CONTACT: Luis Rodriguez, Chief, Engineering Management... Mechanic Falls Town Office, 108 Lewiston Street, Mechanic Falls, ME 04256. Town of Minot Town Office, 329...

Mystery #2 Answer

Atmospheric Science Data Center

2013-04-22

... D.   A lakeside town hosts an annual celebration of Celtic music. Answer: B is false Lake Constance provides drinking water for ... lakeside town of   Konstanz, Germany. An annual Celtic music festival is hosted on the Swiss shores of Lake Constance at the town of ...

TREATY OF GUADALUPE HIDALGO: Definition and List of Community Land Grants in New Mexico. Exposure Draft

DTIC Science & Technology

2001-01-01

grant would receive individual parcels of land designated for dwelling (solar de casa ) and growing food (suerte). Unlike the common lands, these...Sandoval Casa Colorado (Town of) 1823 Socorro Cebolla (Juan Carlos Santistevan) 1846 Taos Domingo Fernández (Ethan W. Eaton; Pueblo de San Cristóbal...Sevilleta (La Joya) 1819 Socorro Socorro (Town of) 1817 Socorro Tierra Amarilla 1832 Río Arriba Town of Abiquiú 1754 Río Arriba Town of Albuquerque 1706

Mechanisms and Observations of Coronal Dimming for the 2010 August 7 Event

NASA Technical Reports Server (NTRS)

Mason, James P.; Woods, Thomas N.; Caspi, Amir; Thompson, Barbara J.; Hock, Rachel A.

2014-01-01

Coronal dimming of extreme ultraviolet (EUV) emission has the potential to be a useful forecaster of coronal mass ejections (CMEs). As emitting material leaves the corona, a temporary void is left behind which can be observed in spectral images and irradiance measurements. The velocity and mass of the CMEs should impact the character of those observations. However, other physical processes can confuse the observations. We describe these processes and the expected observational signature, with special emphasis placed on the differences. We then apply this understanding to a coronal dimming event with an associated CME that occurred on 2010 August 7. Data from the Solar Dynamics Observatory's (SDO) Atmospheric Imaging Assembly (AIA) and EUV Variability Experiment (EVE) are used for observations of the dimming, while the Solar and Heliospheric Observatory's (SoHO) Large Angle and Spectrometric Coronagraph (LASCO) and the Solar Terrestrial Relations Observatory's (STEREO) COR1 and COR2 are used to obtain velocity and mass estimates for the associated CME. We develop a technique for mitigating temperature effects in coronal dimming from full-disk irradiance measurements taken by EVE. We find that for this event, nearly 100% of the dimming is due to mass loss in the corona.

CLOSED-FIELD CORONAL HEATING DRIVEN BY WAVE TURBULENCE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Downs, Cooper; Lionello, Roberto; Mikić, Zoran

To simulate the energy balance of coronal plasmas on macroscopic scales, we often require the specification of the coronal heating mechanism in some functional form. To go beyond empirical formulations and to build a more physically motivated heating function, we investigate the wave-turbulence-driven (WTD) phenomenology for the heating of closed coronal loops. Our implementation is designed to capture the large-scale propagation, reflection, and dissipation of wave turbulence along a loop. The parameter space of this model is explored by solving the coupled WTD and hydrodynamic evolution in 1D for an idealized loop. The relevance to a range of solar conditionsmore » is also established by computing solutions for over one hundred loops extracted from a realistic 3D coronal field. Due to the implicit dependence of the WTD heating model on loop geometry and plasma properties along the loop and at the footpoints, we find that this model can significantly reduce the number of free parameters when compared to traditional empirical heating models, and still robustly describe a broad range of quiet-Sun and active region conditions. The importance of the self-reflection term in producing relatively short heating scale heights and thermal nonequilibrium cycles is also discussed.« less

Planned Visible Emission Line Space Solar Coronagraph on-board Aditya-1

NASA Astrophysics Data System (ADS)

Singh, Jagdev

2012-07-01

An imaging visible emission line internally occulted coronagraph using 20 cm off axis parabolic mirror has been designed and planned to be launched in 2014. The coronagraph will have the facility to take images of the solar simultaneously, in the green [Fe xiv] and the red [Fe x] emission lines up to 1.5 solar radii with a frequency of about 3 Hz using 0.5 nm pass band filters and the images in continuum at 580 nm up to 3 solar radii. The satellite has been named as Aditya-1 and the scientific objectives of this payload are: (i) to investigate the existence of intensity oscillations for the study of wave driven coronal heating, (ii) to study the dynamics and formation of coronal loops and temperature structure of the coronal features, (iii) to study the origin, cause and acceleration of Coronal Mass Ejections (CME's) and other solar active features, and (iv) Coronal magnetic field topology and the 3-dimensional structures of the CMEs using polarization information. The fabrication of the pay load will be done in the laboratories of LEOS, SAC, ISAC, IIA and USO and launched by ISRO. Here we shall discuss the design and the realization of the mission.

MINI-FILAMENT ERUPTION AS THE INITIATION OF A JET ALONG CORONAL LOOPS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hong, Junchao; Jiang, Yunchun; Yang, Jiayan

Minifilament eruptions (MFEs) and coronal jets are different types of solar small-scale explosive events. We report an MFE observed at the New Vacuum Solar Telescope (NVST). As seen in the NVST H α images, during the rising phase, the minifilament erupts outward orthogonally to its length, accompanied with a flare-like brightening at the bottom. Afterward, dark materials are found to possibly extend along the axis of the expanded filament body. The MFE is analogous to large filament eruptions. However, a simultaneous observation of the Solar Dynamics Observatory shows that a jet is initiated and flows out along nearby coronal loopsmore » during the rising phase of the MFE. Meanwhile, small hot loops, which connect the original eruptive site of the minifilament to the footpoints of the coronal loops, are formed successively. A differential emission measure analysis demonstrates that, on the top of the new small loops, a hot cusp structure exists. We conjecture that the magnetic fields of the MFE interact with magnetic fields of the coronal loops. This interaction is interpreted as magnetic reconnection that produces the jet and the small hot loops.« less

Medical examiner/coroner records: uses and limitations in occupational injury epidemiologic research.

PubMed

Conroy, C; Russell, J C

1990-07-01

Epidemiologic research often relies on existing data, collected for nonepidemiologic reasons, to support studies. Data are obtained from hospital records, police reports, labor reports, death certificates, or other sources. Medical examiner/coroner records are, however, not often used in epidemiologic studies. The National Institute for Occupational Safety and Health's Division of Safety Research has begun using these records in its research program on work-related trauma. Because medical examiners and coroners have the legal authority and responsibility to investigate all externally caused deaths, these records can be used in surveillance of these deaths. Another use of these records is to validate cases identified by other case ascertainment methods, such as death certificates. Using medical examiner/coroner records also allows rapid identification of work-related deaths without waiting several years for mortality data from state offices of vital statistics. Finally, the records are an invaluable data source since they contain detailed information on the nature of the injury, external cause of death, and results of toxicologic testing, which is often not available from other sources. This paper illustrates some of the ways that medical examiner/coroner records are a valuable source of information for epidemiologic studies and makes recommendations to improve their usefulness.

Analysis of Solar Coronal Holes with Synoptic Magnetogram Data

NASA Astrophysics Data System (ADS)

Canner, A.; Kim, T. K.; Pogorelov, N.; Yalim, M. S.

2017-12-01

Coronal holes are regions in which the magnetic field of the Sun is open with high magnetic flux and low plasma density. Because of the low plasma beta in these regions, the open field lines transport plasma from the Sun throughout the heliosphere. Coronal hole area is closely related to the expansion factor of the magnetic flux tube, as demonstrated by Tokumaru et al. (2017). Following the approach of Tokumaru et al. (2017), we employ a potential field source surface model to identify the open field regions on the photosphere and estimate the area and expansion factor for each coronal hole. While Tokumaru et al. (2017) analyzed synoptic maps from Kitt Peak National Observatory for the period 1995-2011, we use different magnetograph observations with higher spatial resolution (e.g., SOHO-MDI) for the same time period. We compare the coronal hole area - expansion factor relationship with the original results of Tokumaru et al (2017). This work was supported by the NSF-funded Research Experience for Undergraduates program "Solar and Heliospheric Physics at UAH and MSFC" run by the University of Alabama in Huntsville in partnership with the Marshall Space Flight Center through grant AGS-1460767.

A NuSTAR census of coronal parameters in Seyfert galaxies

NASA Astrophysics Data System (ADS)

Tortosa, A.; Bianchi, S.; Marinucci, A.; Matt, G.; Petrucci, P. O.

2018-06-01

Context. We discuss the results of the hot corona parameters of active galactic nuclei (AGN) that have been recently measured with NuSTAR. The values taken from the literature of a sample of 19 bright Seyfert galaxies are analysed. Aims: The aim of this work is to look for correlations between coronal parameters, such as the photon index and cut-off energy (when a phenomenological model is adopted) or the optical depth and temperature (when a Comptonization model is used), and other parameters of the systems, such as the black hole mass or the Eddington ratio. Methods: We analysed the coronal parameters of the 19 unobscured, bright Seyfert galaxies that are present in the Swift/BAT 70-month catalogue and that have been observed by NuSTAR, alone or simultaneously with others X-ray observatories, such as Swift, Suzaku, or XMM-Newton. Results: We found an anti-correlation with a significance level >98% between the coronal optical depth and the coronal temperature of our sample. On the other hand, no correlation between the above parameters and the black hole mass, the accretion rate, and the intrinsic spectral slope of the sources is found.

Determination of temperature maps of EUV coronal hole jets

NASA Astrophysics Data System (ADS)

Nisticò, Giuseppe; Patsourakos, Spiros; Bothmer, Volker; Zimbardo, Gaetano

2011-11-01

Coronal hole jets are fast ejections of plasma occurring within coronal holes, observed at Extreme-UltraViolet (EUV) and X-ray wavelengths. Recent observations of jets by the STEREO and Hinode missions show that they are transient phenomena which occur at much higher rates than large-scale impulsive phenomena like flares and Coronal Mass Ejections (CMEs). In this paper we describe some typical characteristics of coronal jets observed by the SECCHI instruments of STEREO spacecraft. We show an example of 3D reconstruction of the helical structure for a south pole jet, and present how the angular distribution of the jet position angles changes from the Extreme-UltraViolet-Imager (EUVI) field of view to the CORonagraph1 (COR1) (height ∼2.0 R⊙ heliocentric distance) field of view. Then we discuss a preliminary temperature determination for the jet plasma by using the filter ratio method at 171 and 195 Å and applying a technique for subtracting the EUV background radiation. The results show that jets are characterized by electron temperatures ranging between 0.8 and 1.3 MK. We present the thermal structure of the jet as temperature maps and we describe its thermal evolution.

Thermal stability of static coronal loops: Part 1: Effects of boundary conditions

NASA Technical Reports Server (NTRS)

Antiochos, S. K.; Shoub, E. C.; An, C. H.; Emslie, A. G.

1985-01-01

The linear stability of static coronal-loop models undergoing thermal perturbations was investigated. The effect of conditions at the loop base on the stability properties of the models was considered in detail. The question of appropriate boundary conditions at the loop base was considered and it was concluded that the most physical assumptions are that the temperature and density (or pressure) perturbations vanish there. However, if the base is taken to be sufficiently deep in the chromosphere, either several chromospheric scale heights or several coronal loop lengths in depth, then the effect of the boundary conditions on loop stability becomes negligible so that all physically acceptable conditions are equally appropriate. For example, one could as well assume that the velocity vanishes at the base. The growth rates and eigenmodes of static models in which gravity is neglected and in which the coronal heating is a relatively simple function, either constant per-unit mass or per-unit volume were calculated. It was found that all such models are unstable with a growth rate of the order of the coronal cooling time. The physical implications of these results for the solar corona and transition region are discussed.

A gigantic coronal jet ejected from a compact active region in a coronal hole

NASA Technical Reports Server (NTRS)

Shibata, K.; Nitta, N.; Strong, K. T.; Matsumoto, R.; Yokoyama, T.; Hirayama, T.; Hudson, H.; Ogawara, Y.

1994-01-01

A gigantic coronal jet greater than 3 x 10(exp 5) km long (nearly half the solar radius) has been found with the soft X-ray telescope (SXT) on board the solar X-ray satellite, Yohkoh. The jet was ejected on 1992 January 11 from an 'anemone-type' active region (AR) appearing in a coronal hole and is one of the largest coronal X-ray jets observed so far by SXT. This gigantic jet is the best observed example of many other smaller X-ray jets, because the spatial structures of both the jet and the AR located at its base are more easily resolved. The range of apparent translational velocities of the bulk of the jet was between 90 and 240 km s(exp -1), with the corresponding kinetic energy estimated to be of order of 10(exp 28) ergs. A detailed analysis reveals that the jet was associated with a loop brightening (a small flare) that occurred in the active region. Several features of this observation suggest and are consistent with a magnetic reconnection mechanism for the production of such a 'jet-loop-brightening' event.

Coronal Activity in the R CrA T Association

NASA Technical Reports Server (NTRS)

Patten, Brian M.; Oliversen, Ronald J. (Technical Monitor)

2005-01-01

Brian Patten is the Principal Investigator of the NASA ROSS-ADP project Coronal Activity in the R CrA T Association. For this project we have extracted net counts and variability information for all of the X-ray sources found in 23 archival ROSAT PSPC and HRI images in the region of the R CrA T association. These data have been merged with an extensive database of optical and near-infrared photometry, optical spectroscopy, and parallax data. These data have been used to (1) identify new association members and clarify the membership status of a number of previously suspected members of the association, and (2) derive, for the first time, an accurate coronal luminosity function for the T Tauri members of this T association and make direct comparisons between the coronal luminosity functions for other T associations and those of large clusters. We have used our survey data to assess (a) the importance of the star-formation environment in initial coronal activity levels, (b) the effects of PMS evolution on dynamo activity as a function of mass and age, and (c) the level of contamination by field post-T Tauri stars on association membership surveys.

Loop models of low coronal structures observed by the Normal Incidence X-Ray Telescope (NIXT)

NASA Technical Reports Server (NTRS)

Peres, G.; Reale, F.; Golub, L.

1994-01-01

The X-ray pictures obtained with the Normal Incidence X-Ray Telescope (NIXT), apart from the ubiquitous coronal loops well known from previous X-ray observations, show a new and peculiar morphology: in many active regions there are wide and apparently low-lying areas of intense emission which resemble H alpha plages. By means of hydrostatic models of coronal arches, we analyze the distribution of temperature, density, emission measure, and plasma emissivity in the spectral band to which NIXT is sensitive, and we show that the above morphology can be explained by the characteristics of high pressure loops having a thin region of high surface brightness at the base. We therefore propose that this finding might help to identify high-pressure X-ray emitting coronal regions in NIXT images, and it is in principle applicable to any imaging instrument which has high sensitivity to 10(exp 4) - 10(exp 6) K plasma within a narrow coronal-temperature passband. As a more general result of this study, we propose that the comparison of NIXT observations with models of stationary loops might provide a new diagnostic: the determination of the loop plasma pressure from measurements of brightness distribution along the loop.

A MAGNETOHYDRODYNAMIC MODEL OF THE 2006 DECEMBER 13 ERUPTIVE FLARE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fan, Y.

2011-10-20

We present a three-dimensional magnetohydrodynamic simulation that qualitatively models the coronal magnetic field evolution associated with the eruptive flare that occurred on 2006 December 13 in the emerging {delta}-sunspot region NOAA 10930 observed by the Hinode satellite. The simulation is set up to drive the emergence of an east-west-oriented magnetic flux rope at the lower boundary into a preexisting coronal field constructed from the Solar and Heliospheric Observatory/Michelson Doppler Imager full-disk magnetogram at 20:51:01 UT on 2006 December 12. The resulting coronal flux rope embedded in the ambient coronal magnetic field first settles into a stage of quasi-static rise andmore » then undergoes a dynamic eruption, with the leading edge of the flux rope cavity accelerating to a steady speed of about 830 km s{sup -1}. The pre-eruption coronal magnetic field shows morphology that is in qualitative agreement with that seen in the Hinode soft X-ray observation in both the magnetic connectivity as well as the development of an inverse-S-shaped X-ray sigmoid. We examine the properties of the erupting flux rope and the morphology of the post-reconnection loops, and compare them with the observations.« less

Closed-field Coronal Heating Driven by Wave Turbulence

NASA Astrophysics Data System (ADS)

Downs, Cooper; Lionello, Roberto; Mikić, Zoran; Linker, Jon A.; Velli, Marco

2016-12-01

To simulate the energy balance of coronal plasmas on macroscopic scales, we often require the specification of the coronal heating mechanism in some functional form. To go beyond empirical formulations and to build a more physically motivated heating function, we investigate the wave-turbulence-driven (WTD) phenomenology for the heating of closed coronal loops. Our implementation is designed to capture the large-scale propagation, reflection, and dissipation of wave turbulence along a loop. The parameter space of this model is explored by solving the coupled WTD and hydrodynamic evolution in 1D for an idealized loop. The relevance to a range of solar conditions is also established by computing solutions for over one hundred loops extracted from a realistic 3D coronal field. Due to the implicit dependence of the WTD heating model on loop geometry and plasma properties along the loop and at the footpoints, we find that this model can significantly reduce the number of free parameters when compared to traditional empirical heating models, and still robustly describe a broad range of quiet-Sun and active region conditions. The importance of the self-reflection term in producing relatively short heating scale heights and thermal nonequilibrium cycles is also discussed.

Mechanisms and observations of coronal dimming for the 201 August 7 event

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mason, James Paul; Woods, T. N.; Caspi, A.

2014-07-01

Coronal dimming of extreme ultraviolet (EUV) emission has the potential to be a useful forecaster of coronal mass ejections (CMEs). As emitting material leaves the corona, a temporary void is left behind which can be observed in spectral images and irradiance measurements. The velocity and mass of the CMEs should impact the character of those observations. However, other physical processes can confuse the observations. We describe these processes and the expected observational signature, with special emphasis placed on the differences. We then apply this understanding to a coronal dimming event with an associated CME that occurred on 2010 August 7.more » Data from the Solar Dynamics Observatory's Atmospheric Imaging Assembly and EUV Variability Experiment (EVE) are used for observations of the dimming, while the Solar and Heliospheric Observatory's Large Angle and Spectrometric Coronagraph and the Solar Terrestrial Relations Observatory's COR1 and COR2 are used to obtain velocity and mass estimates for the associated CME. We develop a technique for mitigating temperature effects in coronal dimming from full-disk irradiance measurements taken by EVE. We find that for this event, nearly 100% of the dimming is due to mass loss in the corona.« less

Relation between local restaurant smoking regulations and attitudes towards the prevalence and social acceptability of smoking: a study of youths and adults who eat out predominantly at restaurants in their town.

PubMed

Albers, A B; Siegel, M; Cheng, D M; Biener, L; Rigotti, N A

2004-12-01

To examine the relation between strength of local restaurant smoking regulations and smoking related social norms among youths and adults. We used generalised estimating equations logistic regression analysis to examine the relation between regulation strength and youths' and adults' perceptions of adult smoking prevalence and the social acceptability of smoking in their town, while controlling for baseline anti-smoking sentiment in the town. Each of the 351 Massachusetts towns were classified as having strong (complete smoking ban), medium (restriction of smoking to enclosed, separately ventilated areas), or weak (all others) restaurant smoking regulations. 1147 Massachusetts youths ages 12-17 years and 2116 adults who reported that they often or always eat out in their own town, drawn from a random digit dial survey. Perceived adult smoking prevalence and perceived social acceptability of smoking in restaurants, in bars, or in general. Compared to youths from towns with weak regulations, youths from towns with strong regulations were more likely to perceive lower adult smoking prevalence (odds ratio (OR) 1.71; 95% confidence interval (CI) 1.02 to 2.84) and social unacceptability of adult smoking (OR 2.00, 95% CI 1.29 to 3.08) in their town. Adults from towns with strong regulations were not more likely to perceive lower adult smoking prevalence, but had more than twice the odds of perceiving that smoking was unacceptable in restaurants (OR 2.19, 95% CI 1.58 to 3.02) or bars (OR 2.51, 95% CI 1.90 to 3.31). Strong local restaurant smoking regulations are associated with favourable smoking related social norms among youths and adults.

Relation between local restaurant smoking regulations and attitudes towards the prevalence and social acceptability of smoking: a study of youths and adults who eat out predominantly at restaurants in their town

PubMed Central

Albers, A; Siegel, M; Cheng, D; Biener, L; Rigotti, N

2004-01-01

Objective: To examine the relation between strength of local restaurant smoking regulations and smoking related social norms among youths and adults. Design: We used generalised estimating equations logistic regression analysis to examine the relation between regulation strength and youths' and adults' perceptions of adult smoking prevalence and the social acceptability of smoking in their town, while controlling for baseline anti-smoking sentiment in the town. Setting: Each of the 351 Massachusetts towns were classified as having strong (complete smoking ban), medium (restriction of smoking to enclosed, separately ventilated areas), or weak (all others) restaurant smoking regulations. Subjects: 1147 Massachusetts youths ages 12–17 years and 2116 adults who reported that they often or always eat out in their own town, drawn from a random digit dial survey. Main outcome measures: Perceived adult smoking prevalence and perceived social acceptability of smoking in restaurants, in bars, or in general. Results: Compared to youths from towns with weak regulations, youths from towns with strong regulations were more likely to perceive lower adult smoking prevalence (odds ratio (OR) 1.71; 95% confidence interval (CI) 1.02 to 2.84) and social unacceptability of adult smoking (OR 2.00, 95% CI 1.29 to 3.08) in their town. Adults from towns with strong regulations were not more likely to perceive lower adult smoking prevalence, but had more than twice the odds of perceiving that smoking was unacceptable in restaurants (OR 2.19, 95% CI 1.58 to 3.02) or bars (OR 2.51, 95% CI 1.90 to 3.31). Conclusions: Strong local restaurant smoking regulations are associated with favourable smoking related social norms among youths and adults. PMID:15564617