scholarly journals Analysis of Type II radio burst relationship with CME driven shocks

2021 ◽  
Vol 23 (09) ◽  
pp. 52-64
Author(s):  
Raveesha K.H ◽  
◽  
Vedavathi P ◽  
Vijayakumar H Doddamani ◽  
◽  
...  
Keyword(s):  
Temporal Association ◽  
Type Ii ◽  
Burst Source ◽  
Data Set ◽  
Group Iii ◽  
Shock Speed ◽  
Group I ◽  
Type Ii Radio Bursts ◽  
Type Ii Bursts ◽  
Temporally Correlated

Type II radio bursts are known to be the signatures of coronal shocks. In this paper we examine the relationship between 129 type II bursts in the frequency range 35 – 450 MHz observed at Culgooora observatory during May 2002 – October 2015 and the associated CMEs. We apply Newkirk (1961) density model to determine the formation height of type IIs. We find that in 109/129 cases, type II bursts were preceded/ succeeded by CMEs. The CME associated type II events in which the CME height is above the type II burst source are categorized as group I events (91/129 cases). 91% of the bursts in this group are also associated with flares and 58% of these bursts originate during decaying phase of the flare. The correlation between CME speed and type II shock speed for limb events in this group is 0.33.The CME associated type IIs in which the CME height is below the type II source are categorized as group II (18/129 cases). CME driven shock could have been the exciter of these type II bursts.88% of this group events are associated with flares and 62% of these bursts originate during the rising phase of the flare. The correlation between CME speed and type II shock speed for limb events in this group is 0.96. In 20/129 cases of our data set, type II bursts are not associated with CME and are categorized as group III. 90% of the bursts in this group are associated with flares. 77% of the bursts in the group are originating in the decaying phase of flares. Poor temporal association (9/69 cases) between type IIs and flares of X class during this period. Our results suggest that inspite of temporal association with metric type II bursts, majority of the CME driven shocks (84%) are not successful in exciting type II bursts in 35-450 MHz domain. The type II bursts temporally correlated with CMEs and likely to have been excited by CMEs (type II height > CME height) are originating during the rising phase of the flares in majority of the events. In case of type II bursts temporally correlated with CMEs supposedly not excited by the CMEs (type II height < CME height) ,majority of them are originating in the decaying phase of flares.

scholarly journals Using radio triangulation to understand the origin of two subsequent type II radio bursts

2020 ◽  
Vol 639 ◽  
pp. A56
Author(s):  
I. C. Jebaraj ◽  
J. Magdalenić ◽  
T. Podladchikova ◽  
C. Scolini ◽  
J. Pomoell ◽  
...  
Keyword(s):  
Shock Wave ◽  
Radio Emission ◽  
Spatial Information ◽  
Low Frequency ◽  
Temporal Association ◽  
Type Ii ◽  
Flare Event ◽  
Type Ii Radio Bursts ◽  
Type Ii Bursts ◽  
The Relationship

Context. Eruptive events such as coronal mass ejections (CMEs) and flares accelerate particles and generate shock waves which can arrive at Earth and can disturb the magnetosphere. Understanding the association between CMEs and CME-driven shocks is therefore highly important for space weather studies. Aims. We present a study of the CME/flare event associated with two type II bursts observed on September 27, 2012. The aim of the study is to understand the relationship between the observed CME and the two distinct shock wave signatures. Methods. The multiwavelength study of the eruptive event (CME/flare) was complemented with radio triangulation of the associated radio emission and modelling of the CME and the shock wave employing MHD simulations. Results. We found that, although temporal association between the type II bursts and the CME is good, the low-frequency type II (LF-type II) burst occurs significantly higher in the corona than the CME and its relationship to the CME is not straightforward. The analysis of the EIT wave (coronal bright front) shows the fastest wave component to be in the southeast quadrant of the Sun. This is also the quadrant in which the source positions of the LF-type II were found to be located, probably resulting from the interaction between the shock wave and a streamer. Conclusions. The relationship between the CME/flare event and the shock wave signatures is discussed using the temporal association, as well as the spatial information of the radio emission. Further, we discuss the importance and possible effects of the frequently non-radial propagation of the shock wave.

scholarly journals On Split-Band Structure in Type II Radio Bursts from the Sun

1974 ◽  
Vol 57 ◽  
pp. 389-393 ◽  
Author(s):  
S. F. Smerd ◽  
K. V. Sheridan ◽  
R. T. Stewart
Keyword(s):  
Band Structure ◽  
The Sun ◽  
Radio Bursts ◽  
Type Ii ◽  
Band Splitting ◽  
Measured Amount ◽  
Type Ii Radio Bursts ◽  
Type Ii Bursts ◽  
Split Band

(Astrophys. Letters). The measured amount of band-splitting, Δf, in the spectra of nine harmonic type II bursts is illustrated in Figure 1. Here, as in previous, smaller samples (Roberts, 1959; Maxwell and Thompson, 1962; Weiss, 1965) Δf is found to increase with frequency, f.

On the Possibility of Radio Emission from Quasi-parallel and Quasi-perpendicular Propagation of Shocks

2000 ◽  
Vol 179 ◽  
pp. 259-262
Author(s):  
A. Shanmugaraju ◽  
S. Umapathy
Keyword(s):  
Magnetic Field ◽  
Radio Emission ◽  
Radio Bursts ◽  
Type Ii ◽  
Simple Analysis ◽  
Type Ii Radio Bursts ◽  
Solar Type ◽  
Type Ii Bursts

AbstractA set of 21 solar type II radio bursts observed using Hiraiso radio spectrograph have been analysed to study the direction of propagation of coronal shocks. A simple analysis is carried out to find the approximate angle between the shock normal and magnetic field by solving the Rankine-Hugoniot MHD relation with assumption of Alfven speed and plasma beta. From this analysis, it is suggested that both quasi-parallel shocks (favourable) and quasi-perpendicular shocks can generate type II bursts depending upon the circumstances of the corona.

scholarly journals Coronal mass ejections, type II radio bursts, and solar energetic particle events in the SOHO era

2008 ◽  
Vol 26 (10) ◽  
pp. 3033-3047 ◽  
Author(s):  
N. Gopalswamy ◽  
S. Yashiro ◽  
S. Akiyama ◽  
P. Mäkelä ◽  
H. Xie ◽  
...  
Keyword(s):  
Coronal Mass Ejections ◽  
Energetic Particle ◽  
Solar Energetic Particle ◽  
Western Hemisphere ◽  
Radio Bursts ◽  
Type Ii ◽  
Association Rate ◽  
Type Ii Radio Bursts ◽  
Type Ii Bursts ◽  
Weak Shocks

Abstract. Using the extensive and uniform data on coronal mass ejections (CMEs), solar energetic particle (SEP) events, and type II radio bursts during the SOHO era, we discuss how the CME properties such as speed, width and solar-source longitude decide whether CMEs are associated with type II radio bursts and SEP events. We discuss why some radio-quiet CMEs are associated with small SEP events while some radio-loud CMEs are not associated with SEP events. We conclude that either some fast and wide CMEs do not drive shocks or they drive weak shocks that do not produce significant levels of particle acceleration. We also infer that the Alfvén speed in the corona and near-Sun interplanetary medium ranges from <200 km/s to ~1600 km/s. Radio-quiet fast and wide CMEs are also poor SEP producers and the association rate of type II bursts and SEP events steadily increases with CME speed and width (i.e. energy). If we consider western hemispheric CMEs, the SEP association rate increases linearly from ~30% for 800 km/s CMEs to 100% for ≥1800 km/s. Essentially all type II bursts in the decametre-hectometric (DH) wavelength range are associated with SEP events once the source location on the Sun is taken into account. This is a significant result for space weather applications, because if a CME originating from the western hemisphere is accompanied by a DH type II burst, there is a high probability that it will produce an SEP event.

scholarly journals Role of Apo B and Apo A1 Levels in Relation to Conventional Lipid Profile in Patients of Ischaemic Heart Disease with or without Type II Diabetes Mellitus

2021 ◽  
Author(s):  
Hardik N Javia ◽  
Milav H Bhavsar ◽  
Bhavesh R Sadariya ◽  
Amitkumar V Maheshwari ◽  
Hariom Sharma
Keyword(s):  
Diabetes Mellitus ◽  
Lipid Profile ◽  
Type Ii Diabetes ◽  
Type Ii Diabetes Mellitus ◽  
P Value ◽  
Type Ii ◽  
Apo B ◽  
Group Iii ◽  
Group I ◽  
Group Ii

Introduction: Ischaemic Heart Disease (IHD) or Coronary Artery Disease (CAD) is the most prevalent chronic disease and the main leading cause of death in the world, with more than half a million newly diagnosed IHD patients each year. Central to this are disorders of lipoprotein metabolism. Apolipoprotein B (Apo B) and Apolipoprotein A1 (Apo A1) are structural and functional components of lipoprotein particles that serve as transporters of cholesterol. Apo B and Apo A1 are among the emerging markers for Cardiovascular Diseases (CVD). Routine conventional lipid profile does not incorporate these markers. Aim: To determine the level of Apo A1 and Apo B in patients of IHD with or without Type II Diabetes Mellitus (T2DM) and analyse the significance of these parameters over the conventional lipid profile. Materials and Methods: The case-control study was conducted at Government Medical College, Bhavnagar, Gujarat, India from July 2013 to December 2013. The study consists of 100 participants including 50 having IHD only (Group I), 50 having IHD with T2DM (Group II) as study groups and 50 healthy individuals (Group III) as control. Various biochemical parameters including Apo B and Apo A1 were analysed and statistically evaluated to come to conclusion. Results: The demographic details of the participants which shows no significant different in age and gender among groups I, II and III. Apo B and A1 were elevated in group I and II and were found highly significant (p-value <0.0001) as compared to the group III. There was positive correlation of serum Apo B levels with total cholesterol (r=0.495, p-value <0.0001), Low-Density Lipoproteins (LDL-C) (r=0.526, p-value <0.0001) and Apo A1 (r=0.685, p-value <0.0001) in group I and LDL-C (r=0.468, p-value=0.001) and Apo A1 (r=0.754, p-value <0.0001) in group II. Similarly, Apo A1 levels were positively correlated with Apo B (r=0.685, p<0.0001) in group I and LDL-C (r=0.305, p-value=0.031) and Apo B (r=0.754, p-value <0.0001) in group II. Conclusion: As the Apo B and Apo A1 cover both atherogenic and antiatherogenic lipid parameters respectively, it can be used as a better predictor of development of IHD with and without T2DM in comparison to conventional parameters of lipid profile.

scholarly journals SERUM VISFATIN, INSULIN RESISTANCE AND BETA CELL FUNCTION IN TYPE II DIABETIC PATIENTS AND NON-DIABETIC ADULT OFFSPRING WITH POSITIVE PARENTAL HISTORY OF TYPE II DIABETES MELLITUS

2021 ◽  
Vol 32 (01) ◽  
pp. 22-27
Author(s):  
Tashfeen Ikram ◽  
Muniza Saeed ◽  
Sabiha Iqbal ◽  
Zunairah Hamayun ◽  
Hifza Noor Lodhi ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Beta Cell ◽  
Beta Cell Function ◽  
Cell Function ◽  
Diabetic Patients ◽  
Adult Offspring ◽  
Type Ii ◽  
Group Iii ◽  
Group I ◽  
Type Ii Diabetics

Introduction: Non-diabetic individuals with type II diabetic parents are more susceptible to develop Diabetes. Visfatin; an adipocytokine and an enzyme is linked with glucose metabolism and affected by obesity. It works like insulin in the human body.  It serves as a key enzyme in nicotinamide adenine dinucleotide biosynthesis and plays a pivotal role in glucose mediated insulin secretion. Aims and Objectives: In this study we aimed to determine and compare serum visfatin levels, insulin resistance (HOMA-IR) and beta cell function (HOMA-%B) of type II diabetic patients and non-diabetic adult offspring of type II diabetic parents with that of non-diabetic adult offspring of non-diabetic parents. Material and methods It was a cross-sectional comparative study conducted at Diabetes clinic of Lahore General Hospital (LGH) and department of Physiology, Post Graduate Medical Institute (PGMI), Lahore in 2018. The study groups included thirty type II diabetic subjects (group III) and forty non-diabetic adult offspring of type II diabetic parents (group II). Forty non-diabetic adult offspring of non-diabetic parents served as controls (group I). The subjects were of thirty to fifty years of age. Blood pressure, BMI and waist circumference of every subject was measured. Fasting blood samples of the subjects were analyzed for serum insulin, glucose and visfatin. Insulin resistance (HOMA-IR), insulin sensitivity (HOMA-%S) and beta cell function (HOMA-%β) were also calculated. Results Type II diabetics (group III) had significantly higher serum visfatin, HOMA-IR, and lower HOMA-%S as compared to the controls (group I). No significant difference was found between HOMA-%B of group III and controls. On the contrary, non-diabetic adult offspring of type II diabetic parents (group II) had significantly lower serum visfatin and HOMA-%S while HOMA-%β, HOMA-IR was significantly higher in comparison to the control group (group I). Conclusion Visfatin production seems suppressed in non-diabetic individuals with type II diabetic parents probably due to hyperinsulinemia. Moreover, it has a little role in insulin secretion in these individuals as reflected by their higher HOMA-%B index. However, visfatin’s upregulation in chronic hyperglycemia is indicative of its restorative role in the declined beta-cell function in type II diabetics.

scholarly journals Studies on Longer Wavelength Type II Radio Bursts Associated with Flares and CMEs during the Rise and Decay Phase of 23rd Solar Cycle

2014 ◽  
Vol 2014 ◽  
pp. 1-13 ◽  
Author(s):  
V. Vasanth ◽  
S. Umapathy
Keyword(s):  
Solar Cycle ◽  
Statistical Study ◽  
Decay Phase ◽  
Radio Bursts ◽  
Type Ii ◽  
23Rd Solar Cycle ◽  
Type Ii Radio Bursts ◽  
The Mean ◽  
Type Ii Bursts ◽  
Rise Phase

A statistical study on the properties of CMEs and flares associated with DH-type II bursts in the 23rd solar cycle during the period 1997–2008 is carried out. A sample of 229 events from our recent work is used for the present study (Vasanth and Umapathy, 2013). The collected events are divided into two groups as (i) solar cycle rise phase events and (ii) solar cycle decay phase events. The properties of CMEs in the two groups were compared and the results are presented. It is noted that there is no difference in the properties of type II burst like start frequency and end frequency between the solar cycle rise phase events and decay phase events. The mean CME speed of solar cycle decay phase events (1373 km s−1) is slightly higher than the solar cycle rise phase events (1058 km s−1). The mean CME acceleration of solar cycle decay phase events (−15.18 m s−2) is found to be higher than that of the solar cycle rise phase events (−1.32 m s−2). There exists good correlation between (i) CME speed and width and (ii) CME speed and acceleration for solar cycle decay phase events (R=0.79, R=-0.80) compared to solar cycle rise phase events (R=0.60, R=-0.57). These results indicate that the type II bursts parameters do not depend upon the time of appearance in the solar cycle.

scholarly journals Tracking the Source of Solar Type II Bursts through Comparisons of Simulations and Radio Data

2021 ◽  
Vol 922 (2) ◽  
pp. 203
Author(s):  
Alexander M. Hegedus ◽  
Ward B. Manchester ◽  
Justin C. Kasper
Keyword(s):  
Wind Waves ◽  
Solar Energetic Particle ◽  
Test Case ◽  
Type Ii ◽  
Radio Data ◽  
Synthetic Spectra ◽  
Type Ii Radio Bursts ◽  
Solar Type ◽  
Type Ii Bursts ◽  
Eastern Edge

Abstract The most intense solar energetic particle events are produced by coronal mass ejections (CMEs) accompanied by intense type II radio bursts below 15 MHz. Understanding where these type II bursts are generated relative to an erupting CME would reveal important details of particle acceleration near the Sun, but the emission cannot be imaged on Earth due to distortion from its ionosphere. Here, a technique is introduced to identify the likely source location of the emission by comparing the dynamic spectrum observed from a single spacecraft against synthetic spectra made from hypothesized emitting regions within a magnetohydrodynamic (MHD) numerical simulation of the recreated CME. The radio-loud 2005 May 13 CME was chosen as a test case, with Wind/WAVES radio data being used to frame the inverse problem of finding the most likely progression of burst locations. An MHD recreation is used to create synthetic spectra for various hypothesized burst locations. A framework is developed to score these synthetic spectra by their similarity to the type II frequency profile derived from the Wind/WAVES data. Simulated areas with 4× enhanced entropy and elevated de Hoffmann–Teller velocities are found to produce synthetic spectra similar to spacecraft observations. A geometrical analysis suggests the eastern edge of the entropy-derived shock around (−30°, 0°) was emitting in the first hour of the event before falling off, and the western/southwestern edge of the shock centered around (6°, −12°) was a dominant area of radio emission for the 2 hr of simulation data out to 20 solar radii.

scholarly journals Squalene decreased malondialdehyde level of diabetic rats

2021 ◽  
Vol 912 (1) ◽  
pp. 012054
Author(s):  
T Widyawati ◽  
S Syarifah ◽  
I B Sumantri
Keyword(s):  
Biological Activities ◽  
Diabetic Rats ◽  
Type Ii ◽  
Once Daily ◽  
Group Iii ◽  
Diabetes Type Ii ◽  
Group I ◽  
Activity Marker ◽  
Metabolite Synthesis ◽  
Post Hoc

Abstract Squalene, a precursor for the secondary metabolite synthesis, is synthesized in animals, bacteria, fungi and plants. It has been reported to have some biological activities, one of which is as an antioxidant. This study aimed to evaluate the effect of squalene on malondialdehyde (MDA) level, an antioxidant activity marker, in diabetic rats. Diabetes type II was induced by a high-fat diet with low dose streptozotocin (30 mg/kg) intraperitoneally. A total of 12 diabetic rats were divided into 3 groups and served once daily for 14 days as follows; Group I (Squalene (S) 160 mg/kg), Group II (Metformin (M) 45 mg/kg) and Group III Aquades (DC) 10 ml/kg). MDA level were measured using Elisa method. Data were analyzed using Kruskall Wallis and Mann-Whitney as post hoc test. The results showed that MDA level in both S- (8.50 ± 1.40 µmol/L) and M- (7.74 ± 1.63 µmol/L) were lower than DC-treated groups (12.82± 2.86 µmol/L). Statistically, significant different were found between S- and DC- as well as Sand M-treated groups (p< 0.05). This study suggested that squalene able to decrease MDA level in type II diabetic rats.

scholarly journals Satellite passive microwave sea-ice concentration data set intercomparison: closed ice and ship-based observations

2019 ◽  
Vol 13 (12) ◽  
pp. 3261-3307 ◽  
Author(s):  
Stefan Kern ◽  
Thomas Lavergne ◽  
Dirk Notz ◽  
Leif Toudal Pedersen ◽  
Rasmus Tage Tonboe ◽  
...  
Keyword(s):  
Sea Ice ◽  
The Arctic ◽  
Data Sets ◽  
Sea Ice Concentration ◽  
Data Set ◽  
Group Iii ◽  
Group I ◽  
Ice Concentration ◽  
Group Ii ◽  
The Antarctic

Abstract. We report on results of a systematic inter-comparison of 10 global sea-ice concentration (SIC) data products at 12.5 to 50.0 km grid resolution for both the Arctic and the Antarctic. The products are compared with each other with respect to differences in SIC, sea-ice area (SIA), and sea-ice extent (SIE), and they are compared against a global wintertime near-100 % reference SIC data set for closed pack ice conditions and against global year-round ship-based visual observations of the sea-ice cover. We can group the products based on the concept of their SIC retrieval algorithms. Group I consists of data sets using the self-optimizing EUMETSAT OSI SAF and ESA CCI algorithms. Group II includes data using the Comiso bootstrap algorithm and the NOAA NSIDC sea-ice concentration climate data record (CDR). The standard NASA Team and the ARTIST Sea Ice (ASI) algorithms are put into group III, and NASA Team 2 is the only element of group IV. The three CDRs of group I (SICCI-25km, SICCI-50km, and OSI-450) are biased low compared to a 100 % reference SIC data set with biases of −0.4 % to −1.0 % (Arctic) and −0.3 % to −1.1 % (Antarctic). Products of group II appear to be mostly biased high in the Arctic by between +1.0 % and +3.5 %, while their biases in the Antarctic range from −0.2 % to +0.9 %. Group III product biases are different for the Arctic, +0.9 % (NASA Team) and −3.7 % (ASI), but similar for the Antarctic, −5.4 % and −5.6 %, respectively. The standard deviation is smaller in the Arctic for the quoted group I products (1.9 % to 2.9 %) and Antarctic (2.5 % to 3.1 %) than for group II and III products: 3.6 % to 5.0 % for the Arctic and 4.0 % to 6.5 % for the Antarctic. We refer to the paper to understand why we could not give values for group IV here. We discuss the impact of truncating the SIC distribution, as naturally retrieved by the algorithms around the 100 % sea-ice concentration end. We show that evaluation studies of such truncated SIC products can result in misleading statistics and favour data sets that systematically overestimate SIC. We describe a method to reconstruct the non-truncated distribution of SIC before the evaluation is performed. On the basis of this evaluation, we open a discussion about the overestimation of SIC in data products, with far-reaching consequences for surface heat flux estimations in winter. We also document inconsistencies in the behaviour of the weather filters used in products of group II, and we suggest advancing studies about the influence of these weather filters on SIA and SIE time series and their trends.

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